Absorption Bands In Spectra Research Articles

Effect of Substitutional Metallic Impurities on the Optical Absorption Properties of TiO2.

(TiO2) is both a natural and artificial compound that is transparent under visible and near-infrared light. However, it could be prepared with other metals, substituting for Ti, thus changing its properties. In this article, we present density functional theory calculations for Ti(1-x)AxO2, where A stands for any of the eight following neutral substitutional impurities, Fe, Ni, Co, Pd, Pt, Cu, Ag and Au, based on the rutile structure of pristine TiO2. We use a fully unconstrained version of the density functional method with generalized gradient approximation plus the U exchange and correlation, as implemented in the Quantum Espresso free distribution. Within the limitations of a finite-size cell approximation, we report the band structure, energy gaps and absorption spectrum for all these cases. Rather than stressing precise values, we report on two general features: the location of the impurity levels and the general trends of the optical properties in the eight different systems. Our results show that all these substitutional atoms lead to the presence of electronic levels within the pristine gap, and that all of them produce absorptions in the visible and near-infrared ranges of electromagnetic radiation. Such results make these systems interesting for the fabrication of solar cells. Considering the variety of results, Ni and Ag are apparently the most promising substitutional impurities with which to achieve better performance in capturing the solar radiation on the planet's surface.

Strongly Bound Excitons and Anisotropic Linear Absorption in Monolayer Graphullerene.

Graphullerene is a novel two-dimensional carbon allotrope with unique optoelectronic properties. Despite significant experimental characterization and prior density functional theory calculations, unanswered questions remain as to the nature, energy, and intensity of the electronic and optical excitations. Here, we present first-principles calculations of the quasiparticle band structure, neutral excitations, and absorption spectra of monolayer graphullerene and bulk graphullerite, employing the GW-Bethe-Salpeter equation (GW-BSE) approach. We show that strongly bound excitons dominate the absorption spectrum of monolayer graphullerene with binding energies up to 0.8 eV, while graphullerite exhibits less pronounced excitonic effects. Our calculations also reveal a strong linear polarization anisotropy, reflecting the in-plane structural anisotropy from intermolecular coupling between neighboring C60 units. We further show that the presence of Mg atoms, crucial to the synthesis process, induces structural modifications and polarizability effects, resulting in a ∼1 eV quasiparticle gap renormalization and a reduction in the exciton binding energy to ∼0.6 eV.

Theoretical prediction of broadband ambient light optogenetic vision restoration with ChRmine and its mutants

Vision restoration is one of the most promising applications of optogenetics. However, it is limited due to the poor-sensitivity, slow-kinetics and narrow band absorption spectra of opsins. Here, a detailed theoretical study of retinal ganglion neurons (RGNs) expressed with ChRmine, ReaChR, CoChR, CatCh and their mutants, with near monochromatic LEDs, and broadband sunlight, halogen lamp, RGB LED light, and pure white light sources has been presented. All the opsins exhibit improved light sensitivity and larger photocurrent on illuminating with broadband light sources compared to narrow band LEDs. ChRmine allows firing at ambient sunlight (1.5 nW/mm2) and pure white light (1.2 nW/mm2), which is lowest among the opsins considered. The broadband activation spectrum of ChRmine and its mutants is also useful to restore color sensitivity. Although ChRmine exhibits slower turn-off kinetics with broadband light, high-fidelity spikes can be evoked upto 50 Hz. This limit extends upto 80 Hz with the improved hsChRmine mutant although it requires double the irradiance compared to ChRmine. The present study shows that ChRmine and its mutants allow activation of RGNs with ambient light which is useful for goggle-free white light optogenetic retinal prostheses with improved quality of restored vision.

Dual-Channel Mapping–Gas Column Concentration Inversion Method Based on Multispectral Imaging

Infrared multispectral imaging technology can achieve the long-distance, wide-ranging and fast detection of target gas, and has been widely used in the fields of dangerous-gas detection and environmental monitoring. However, due to the difficulty in acquiring background radiation as well as atmospheric disturbance and noise interference in the detection process, the quantitative detection of gas concentration has become a difficult problem to solve. Therefore, this paper proposes an inversion method for gas column concentration based on infrared multispectral imaging technology. Firstly, infrared background radiation images of the non-target gas absorption spectrum band were collected and converted into background radiation images of the target gas absorption spectrum band according to the dual-channel mapping relationship. Then, combined with the gas radiation images of the target gas absorption spectrum band, the column concentration distribution of the gas was obtained by using the measured calibration relationship between absorbance and column concentration. Experiments of gas detection in different environments were carried out, and the column concentration distribution of the target gas was inverted using this method; the results showed that the average relative error of the inversion of the gas column concentration was 4.84%, which enables the quantitative detection of gas column concentration in a complex environment.

Impact of extended π-conjugated acceptor moieties on non-linear optical behavior in polar medium for designed 4,4-dimethyl-4H-indeno[1,2-b] thiophene based materials

In the current study, the organic compounds (D2-D9) with D1–π–D2–π–A configuration were designed by structural modeling with various end-capped acceptor moieties for nonlinear optical (NLO) study. TD-DFT/DFT approaches at CAM-B3LYP/6-311G(d,p) level were accomplished to investigate the NLO behavior of these compounds. For this, various analyses: frontier molecular orbitals (FMOs), density of states (DOS), UV–Vis absorption, natural bond orbitals (NBOs), transition density matrix (TDMs) and non-linear optical (NLO) investigations were performed. These findings revealed that all designed chromophores exhibited comparable band gaps (3.962–4.182 eV) and absorption spectra (λmax = 441.6–460.7 nm) with reference chromophore (band gap = 4.008 eV). An efficient charge transfer from central core in HOMO was transferred towards terminal acceptors in LUMO that was also supported by DOS and TDM maps. Among all studied chromophores, the significant linear and nonlinear polarizability properties were examined in D5 (<α>=2.213 × 10-22esu), D6 (βtot = 3.339 × 10-28esu) and D4 (γtot = 3.068 × 10-33esu) chromophores. The NLO results indicated that the designed compounds (D5, D6 and D4) possess promising NLO behavior via effective charge delocalization. It is inferred that the current computational work might be helpful for further developments in non-linear optic field.

Obtaining and characterization of MAPbSnBr3 perovskite crystals trough AVC method

The obtaining tin-based perovskite from solution is challenging due to the rapid and uncontrollable crystallization of tin compared to lead-based perovskite. Another challenge is to reduce the use of lead to avoid poisoning. In this sense, Sn-based perovskite compounds such as CsSnBr3 have attracted great attention as an effective replacement, but current photovoltaic devices still problems of low efficiency and instability chemistry. The band gap of ASnX3 compounds is between 1.2 and 1.4 eV, being the ideal range for maximum theoretical efficiency in a solar cell. In contrast, APbX3 compounds have band gaps in the range of 1.45 to 1.6 eV. We synthesize MAPbSnBr3 perovskite crystals through the AVC method. The structural properties of the crystals were obtained by X-ray diffraction, Raman spectroscopy, these shown the presence of Sn and Pb in the crystals obtained, and the optical properties by UV-Vis absorption and photoluminescence spectroscopy obtaining the variation of the band gap in the perovskite.The results obtained from the MAPbSnBr3 perovskite (such as the band gap, absorption spectrum and crystal lattice) meet the necessary requirements for its possible application in photovoltaic devices. It is shown that it is possible to obtain MAPbSnBr3 crystals with a lower amount of Pb and how the bandgap is affected by varying these elements, for their possible application in solar cells.

Classification and spectrum optimization method of grease based on infrared spectrum

AbstractThe infrared (IR) absorption spectral data of 63 kinds of lubricating greases containing six different types of thickeners were obtained using the IR spectroscopy. The Kohonen neural network algorithm was used to identify the type of the lubricating grease. The results show that this machine learning method can effectively eliminate the interference fringes in the IR spectrum, and complete the feature selection and dimensionality reduction of the high-dimensional spectral data. The 63 kinds of greases exhibit spatial clustering under certain IR spectrum recognition spectral bands, which are linked to characteristic peaks of lubricating greases and improve the recognition accuracy of these greases. The model achieved recognition accuracy of 100.00%, 96.08%, 94.87%, 100.00%, and 87.50% for polyurea grease, calcium sulfonate composite grease, aluminum (Al)-based grease, bentonite grease, and lithium-based grease, respectively. Based on the different IR absorption spectrum bands produced by each kind of lubricating grease, the three-dimensional spatial distribution map of the lubricating grease drawn also verifies the accuracy of classification while recognizing the accuracy. This paper demonstrates fast recognition speed and high accuracy, proving that the Kohonen neural network algorithm has an efficient recognition ability for identifying the types of the lubricating grease.

VTe2: Broadband Saturable Absorber for Passively Q-Switched Lasers in the Near- and Mid-Infrared Regions.

In this study, we demonstrate the fabrication of a novel 2D transition metal dichalcogenide, VTe2, into a saturable absorber (SA) by using the liquid phase exfoliation method. Furthermore, the first-principles calculations were conducted to elucidate the electronic band structures and absorption spectrum. The nonlinear optical absorption properties of VTe2 at 1.0, 2.0, and 3.0 μm were measured using open-aperture Z-scan and P-scan methods, which showed saturation intensities and modulation depths of 95.57 GW/cm2 and 9.24%, 3.11 GW/cm2 and 7.26%, and 15.8 MW/cm2 and 17.1%, respectively. Furthermore, in the realm of practical implementation, the achievement of stable passively Q-switched (PQS) lasers employing SA composed of few-layered VTe2 nanosheets has manifested itself with broadband operating wavelengths from 1.0 to ∼3.0 μm. Specifically, PQS laser operations from near-infrared to mid-infrared with pulse durations of 195 and 563 ns for 1.0 and 2.0 μm solid-state lasers, respectively, and 749 ns for an Er3+-doped fluoride fiber laser at 3.0 μm were obtained. Our experimental results demonstrate that VTe2 is a potential broadband SA device for achieving PQS lasers. To the best of our knowledge, this is the first demonstration of using VTe2 as an SA in PQS lasers in the near- and mid-infrared regions, which highlights the potential of VTe2 for future research and applications in optoelectronic devices.

Fabrication of lanthanum-ferrite perovskite oxide (LaFeO3) using Terminalia arjuna leaf extract for the efficient photocatalytic degradation of malachite green

ABO3-resembled perovskite oxides have been extensively used for heterogeneous catalysis and energy storage applications. In current work, lanthanum-ferrite (LaFeO3) perovskite oxide (PO) has been prepared using Terminalia arjuna (TA) leaf extract followed by evaluation of its degradation efficacy against malachite green (MG) under UV-light. Synthesized PO was analyzed using different state of the art analytical techniques. FTIR peaks appearing at 3608, 645, and 552 cm−1 evident the formation of PO while in UV–Visible spectrum absorption band at 420 nm confirmed the same. The crystallinity of the synthesized PO was determined through XRD which confirmed hexagonal structure having crystallite size about 25.78 nm and FESEM exhibited seaweed-like morphology of PO. The results of dye degradation studies have shown excellent percentage degradation (88.7 %) of MG in the presence of PO and the reaction followed zero-order kinetics. Effect of different factors on degradation of MG dye was also recorded and possible mechanism of dye degradation has also been presented. On the basis of current study, authors have concluded that lanthanum-ferrite LaFeO3 perovskite oxide can be synthesized employing green method with efficient dye degradation potential. The results will be helpful in designing and synthesizing ABO3-resembled perovskite oxides using green method based on plant extract.

High carrier mobilities and broad absorption spectra in twisted and non-twisted bilayer GaN, BN, and ZnO structures

Stacking is effective in modulating the properties of two-dimensional (2D) materials, and more interesting properties exist in twisted stacking systems. The electronic and optical properties of twisted-13.17°, twisted-21.78°, and non-twisted-AA’ structures of GaN, BN, and ZnO have been studied by using first-principles. The calculated results indicate that all structures are stable, and the band gaps of the three structures are modulated effectively. Compared with the monolayer, the twisted structures of GaN, BN, and ZnO can enhance absorption peaks and broaden the absorption spectra. The carrier mobilities of the twisted and non-twisted structures have been investigated by using DP theory. The twisted-13.17° and twisted-21.78° structures of the BN exhibit much high hole mobilities along the y direction of 55.92 and 44.30 @103 cm2 V−1 s−1 respectively. The twisted-13.17° structure of ZnO exhibits much high electron mobilities of 56.81 (x direction) and 16.57 (y direction) @103 cm2 V−1 s−1. The band gap, carrier mobility, and absorption spectrum of the twisted and non-twisted GaN, BN, and ZnO stacking structures have been modulated effectively, and these stacking structures will promise important application prospects in the field of ultraviolet broadband electronic devices and photoelectric devices.

Minimal Molecular Building Blocks for Screening in Quasi-Two-Dimensional Organic-Inorganic Lead Halide Perovskites.

Layered hybrid organic-inorganic lead halide perovskites have intriguing optoelectronic properties, but some of the most interesting perovskite systems, such as defective, disordered, or mixed perovskites, require multiple unit cells to describe and are not accessible within state-of-the-art ab initio theoretical approaches for computing excited states. The principal bottleneck is the calculation of the dielectric matrix, which scales formally as O(N4). We develop here a fully ab initio approximation for the dielectric matrix, known as IPSA-2C, in which we separate the polarizability of the organic/inorganic layers into minimal building blocks, thus circumventing the undesirable power-law scaling. The IPSA-2C method reproduces the quasi-particle band structures and absorption spectra for a series of Ruddlesden-Popper perovskites to high accuracy, by including critical nonlocal effects neglected in simpler models, and sheds light on the complicated interplay of screening between the organic and inorganic sublattices.

Hydrogen sulfide measurement of combustion gaseous product using ultraviolet absorption spectroscopy

Measurement of hydrogen sulfide (H2S) in gaseous product can provide direct reference for high-temperature corrosion of industrial combustion equipment. Aiming at the interference effect of overlapping measurement of absorption spectrum for H2S and other combustion gas components in UV absorption spectroscopy, the simulation calculation of ultraviolet band absorption spectrum of the typical gaseous products of coal combustion were carried out. The cross interference effects of combustion gaseous products were analyzed in detail. Due to the SO2 and H2S gas under typical combustion condition have equivalent absorption strength in the 228 nm-233 nm band, the influence of SO2 on H2S concentration inversion must be emphatically considered, and the inversion algorithm of H2S gas concentration under the background interference of combustion gaseous products SO2 was put forward. In order to validate the measurement accuracy by the inversion algorithm, the measurement experiments of gas mixture of H2S and SO2 were carried out. The results show that the algorithm can effectively solve the problem of cross interference between the detection of H2S and SO2 in the combustion gaseous products by UV absorption spectroscopy. On this basis, the sampling, pre-treatment and H2S gas concentration measurement system for boiler flue gas near the wall was developed and applied to measure H2S concentration of flue gas near the wall in a 1000 MW ultra-supercritical coal-fired power generation boiler. The results can provide important references for combustion adjustment and high-temperature corrosion prevention of boiler.

SYNTHESIS AND SIMPLE METHOD OF CHARACTERIZATION OF ALDEHYDE-SILICA GEL

Two approaches to the functionalization of the silica gel surface have been proposed, which make it possible to obtain materials with covalently immobilized highly reactive aldehyde groups. Immobilization of aldehyde groups in the first case is achieved by the click-reaction of azido-alkyne cycloaddition of 4-(prop-2-in-1-yloxy)benzaldehyde and 3-azidopropyl silica gel. In the second case, surface modification is performed by the alkylation reaction of hydroxybenzaldehydes with 3-chloropropyl silica gel. The obtained silica gel samples were characterized by infrared spectroscopy and thermogravimetric analysis data. In IR spectra absorption bands determination of aldehyde groups on the silica gel surface using 2.4 -dinitrophenylhydrazine has been proposed. The proposed method is based on the condensation reaction between the aldehyde groups grafted on the surface and 2.4 -dinitrophenylhydrazine. The quantitative estimation of the grafted aldehyde groups is suggested to be calculated by the difference between the initial amount of 2.4-dinitrophenylhydrazine and the amount remaining in the solution after the reaction. The necessity of maintaining a constant acidity of the medium by adding H2SO4 was established. It is shown that at λ = 315 nm the Bouguer-Beer-Lambert Law is satisfied in the concentration range 2.5∙10-5 to 12.5∙10-5 M. The correctness of the proposed method was checked using the procedure of operative control of the correctness of the results of chemical analysis. This procedure provides the determination of aldehyde groups in the modified material by multiply varying the silica gel weight and using the root-mean-square deviation of the repeatability of measurement results as an error characteristic. The proposed method for determining the aldehyde groups was tested on all silica gel samples. It was shown that by varying the conditions of surface modification it is possible to obtain materials with different functional capacity for aldehyde groups.

Cancer bioimaging using dual mode luminescence of graphene/FA-ZnO nanocomposite based on novel green technique

Graphene based nanomaterials are explored in the field of cancer bioimaging and biomedical science and engineering. The luminescent nanostructures with a low toxicity and high photostability can be used as probes in bioimaging applications. This work is aimed to prepare graphene/folic acid-zinc oxide (GN/FA-ZnO) nanocomposite with dual-mode emissions (down-conversion and up-conversion) to be used in cancer bioimaging. The dual mode emissions offer long luminescence lifetime, multicolor emissions detected by the naked eyes after excitation and narrow band absorption and emission spectra. ZnO nanospheres and nanorods structures were prepared using co-precipitation technique and were conjugated with FA to separate the bulk graphite layers electrostatically into GN. The optical, morphological, surface charge and structural properties of the prepared nanostructures were investigated and discussed using different characterization techniques such as UV–visible spectroscopy, photoluminescence (PL) spectroscopy, scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), Zeta potential, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and Fourier transform infrared (FTIR). GN/FA-ZnO nanocomposites were injected into Swiss albino mice implanted with Ehrlich Tumor and the bioimaging was investigated using photon imager and digital camera. The results showed clear fluorescence and confirmed that the green design of GN/FA-ZnO nanocomposite with targeting behavior was capable of selective bioimaging of the tumor. This study presented a novel dual mode emission nanocomposite for tumor targeting and is a promising strategy for the fabrication of a new design of spectral encoding.

Degradation of Milkfish Bone (Chanos- chanos Forsskal) with Pure Papain Enzyme Concentration and Heating Time

Aim: This study aimed to determine the physicochemical characteristics of calcium phosphate derivatives of milkfish bones (Chanos-chanos Forsskal) with treatment pure papain enzyme concentration and heating time.&#x0D; Study Design: The experimental design used was a factorial complete randomized design, namely factor A = hydrolysis with the use of pure papain enzymes and factor B was heating time using a temperature of 60oC, each treatment was repeated 3 times.&#x0D; Place and Duration of Study: Research was carried out from September 2018 to July 2019, Agroindustry Workshop, and Chemical Laboratory, Department of Fishery Product Processing Technology, Pangkep State Agricultural of Polytechnic, Physics Laboratory, Science Center, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Chemistry Laboratory, Makassar State Islamic University, Inorganic Chemistry Laboratory MIPA Lampung State University.&#x0D; Methodology: Milkfish bones were added with distilled water and pure papain enzyme at pH 8 with a concentration of 4%, 6% and 8%, degraded by heating at 60°C for 6, 8, and 10 hours after extraction, result were then dried in oven at 50°C. After drying, it ground with a bone crusher. The flour was analyzed, namely: physical tests including yield, whiteness degree, proximate test including moisture content, ash content, protein content, fat content, calcium, phosphorus, functional groups using FTIR, crystallinity using XRD, morphology using SEM/EDS.&#x0D; Results: The results of the analysis of the concentration of pure papain enzyme 8% with a heating time of 10 hours gave the best result, obtained 3.24% moisture content, 83.28% ash content, 10.28% protein, 3.20% fat, 49.30% calcium, 29.17% phosphorus, 7.16% yield, 88.68% whiteness. FTIR analysis has carboxyl groups (OH-), carbonate groups (CO32-) and phosphate groups (PO43-). These are the main components of hydroxyapatite formation where the phosphate absorption band spectra (PO43-) are at a wave frequency of 403.60 cm-1 with an intensity 36.568% is V3PO43- The crystallinity of calcium phosphate derivatives is 74.53% µm hydroxylapatite, 11.94% tricalcium phosphate µm, 13.53% dicalcium phosphate µm. Morphology of Calcium Phosphate Derivative Compounds using XRD, which showed a degree of crystallinity of 73.04% and a crystal size of 4.717 µm.&#x0D; Conclusion: The result of the analysis obtained by the combination treatment of pure papain enzyme concentration of 8% with a heating time of 10 hours are the best of the other treatment.

Corrections of band gaps and optical spectra of N-doped Sb2Se3 from G0W0 and BSE calculations

Nitrogen (N) doped Sb2Se3 semiconductor material shows potential as promising candidate for solar cell application. However, accurate calculations of its basic physical properties have been lacking. In this paper, G0W0 band gap and absorption spectrum of N-doped Sb2Se3 were studied theoretically using G0W0 approximation in combination with Bethe-Salpeter Equation (BSE), which consider the effects of electron-electron (e-e) and electron-hole (e-h) interactions. These methods are chosen and converged carefully in order to yield quantitative results in agreement with experimental data. Our band structure results revealed that apart from a rigid shift of the conduction bands in the G0W0 approach the qualitative features with that obtained within bare DFT are identical. The calculated bandgap values for Sb15N1Se24, Sb14N2Se24, Sb16Se23N1 and Sb16Se22N2 with G0W0 approximation were found to be 1.02, 0.82, 0.92 and 0.81 eV, respectively. These results showed that the bandgap values reduced by substituting N atom at Se and Sb sites in comparison to the undoped Sb2Se3. Reduction of bandgap values by substituting N atoms at Sb and Se sites are in good agreement with previous works. In the BSE calculations, inclusion of e-e and e-h interactions lead to the existence of strong exciton below the G0W0 optical band gap. The value of optical gaps which corresponding to the first peak in the BSE calculations were found to be 0.89, 0.76, 0.86 and 0.76 eV for Sb15N1Se24, Sb14N2Se24, Sb16Se23N1and Sb16Se22N2 respectively. Our theoretical study of N-doped Sb2Se3 suggests that a device fabricated from this materials can be operated on a wide range of the energy scale such as solar cell and broadband photodetector.

The Effect of Extraction Method on the Extract Yield in the Carotenoid Pigment Encapsulation for Halal Natural Pigment

The Soxhlet and maceration methods were used to determine the extract yield in the carotenoid pigment encapsulation for halal natural pigment production. This study aims to obtain halal natural pigment by determining the highest extract yield from the encapsulation of β-carotene in carrots. The carrot was extracted using Soxhlet and maceration method and then continued by oven drying. The n-hexane was selected because of its better volatility than ethanol and provided less solvent residue after extraction. UV-Vis spectroscopy and Thin Layer Chromatography (TLC) were used to characterize the n-hexane yield extract. Encapsulation of the pigment was investigated by adding five grams of maltodextrin to extract n-hexane weights of 0.05, 0.50, 0.75, and 1.0 grams. The maceration method yielded a much higher yield than the Soxhlet extraction method, with 2.24% (w/w) and 0.88% (w/w), respectively. The n-hexane extract absorbed a maximum wavelength of 450 nm with a retention factor (Rf) of 0.62. These values are confirmed by comparing the band's Rf values and absorption spectra with the standard’s. Light absorption spectra at wavelengths 350-500 nm confirmed an intense color expression for encapsulation containing the highest pigment concentration.

A novel aging characterization method for silicone rubber based on terahertz absorption spectroscopy

To address the challenge of the lack of aging characterization methods for outdoor silicone rubber-based insulation materials in power engineering applications, this paper proposes a novel high precision non-destructive characterization method for aging of organic materials based on the vibration characteristics of silicone rubber materials in the terahertz frequency band. In order to analyze and verify the method proposed in this paper, the sources of vibration peaks in the THz band absorption spectrum of aged silicone rubber are discussed by accelerating test, microscopic characterization, and molecular simulation. Finally, the characteristic peak frequency and quantitative calculation method of aged silicone rubber are obtained. Compared to other aging assays, this method overcomes the limitations of the existing THz assay which requires testing in a nitrogen atmosphere, and has the advantage of not damaging the sample.

Evaluating the Influence of Deficit Irrigation on Fruit Yield and Quality Indices of Tomatoes Grown in Sandy Loam and Silty Loam Soils

The most important biotic stress factor impacting tomato crop biophysical, biochemical, physiological, and morphological features is water stress. A pot experiment was undertaken in a greenhouse to study the drought responsiveness of tomato (Solanum lycopersicum) yield and quality indices in sandy loam and silty loam soils. For both sandy loam and silty loam soils, the water supply levels were 70–100% FC, 60–70% FC, 50–60% FC, and 40–50% FC of ETo (crop evapotranspiration) from the vegetative stage to the fruit ripening stage, calculated using the Hargreaves–Samani (HS) model compared to the time-domain reflectometer (TDR) values calibrated using volumetric water content (VWC). The experiment was conducted as a 2 × 4 factorial experiment, arranged in a completely randomized block design, with four treatments replicated four times. In this study, we examined how sandy loam and silty loam soils at different % FC affect the total marketable yield and quality components of tomatoes, concentrating on total soluble solids (Brix), fruit firmness, dry fruit mass, pH, titratable acid (TA), ascorbic acid (Vit. C), and carotenoid composition. Lycopene and β-Carotene were estimated using the UV spectroscopy method, with absorption spectra bands centered at 451 nm, 472 nm, 485 nm, and 502 nm. The results revealed that even though there were some limitations, TDR-based soil moisture content values had a strong positive correlation with HS-based evapotranspiration, with R2 = 0.8, indicating an improvement whereby TDR can solely be used to estimate soil water content. Tomato plants subjected to 40–50% FC (ETo) water stress in both sandy loam and silty loam soils recorded the highest total soluble solids, titratable acidity, ascorbic acid content, and β-carotene content at an absorption peak of 482 nm, and lycopene content at an absorption peak of 472 nm, with lower fruit firmness, fruit juice content, and fruit juice pH, and a reduced marketable yield. Similarly, tomato plants subjected to 60–70% FC throughout the growing season achieved good fruit firmness, percent juice content, total soluble solids, titratable acidity, ascorbic acid content, and chlorophyll content (SPAD), with minimum fruit juice pH and high marketable yield in both soil textural types. It is concluded that subjecting tomato plants to 60–70% FC (ETo) has a constructive impact on the marketable yield quality indices of tomatoes.

GaN/MgI2 van der Waals heterostructure: a two-factor tunable photocatalyst for hydrogen evolution.

With the increasing environmental pollution and energy crisis, it is significant to develop environmentally friendly and adjustable photocatalysts for water splitting. Here we explored the optoelectronic properties of several H-GaN/MgI2 vdW heterostructures by regulating different polarization surfaces and numbers of GaN layers. Our results demonstrate that all structures, except 2L-Ga-GaN/MgI2, exhibit excellent physical stability. Moreover, the band structures and band edge positions demonstrate that only the heterostructure of 3L-Ga-GaN/MgI2 with both suitable band alignment (type-II) and an acceptable band gap (∼1.92 eV) is most satisfactory for water splitting. Additionally, the absorption coefficient of the 3L-Ga-GaN/MgI2 heterostructure can reach over ∼105 cm-1, which has further confirmed its excellent advantage in photocatalysis. Finally, in the case of 6% external strain for the 3L-Ga-GaN/MgI2 heterostructure, a rollover in band alignment (from type-II to type-I) is exhibited. These promising features of the GaN/MgI2 vdW heterostructure give a new paradigm for developing novel efficient and adjustable photocatalytic water-splitting materials.