Marine microalgae and seaweeds (microalgae) represent a sustainable source of various bioactive natural carotenoids, including β-carotene, lutein, astaxanthin, zeaxanthin, violaxanthin and ...fucoxanthin. Recently, the large-scale production of carotenoids from algal sources has gained significant interest with respect to commercial and industrial applications for health, nutrition, and cosmetic applications. Although conventional processing technologies, based on solvent extraction, offer a simple approach to isolating carotenoids, they suffer several, inherent limitations, including low efficiency (extraction yield), selectivity (purity), high solvent consumption, and long treatment times, which have led to advancements in the search for innovative extraction technologies. This comprehensive review summarizes the recent trends in the extraction of carotenoids from microalgae and seaweeds through the assistance of different innovative techniques, such as pulsed electric fields, liquid pressurization, supercritical fluids, subcritical fluids, microwaves, ultrasounds, and high-pressure homogenization. In particular, the review critically analyzes technologies, characteristics, advantages, and shortcomings of the different innovative processes, highlighting the differences in terms of yield, selectivity, and economic and environmental sustainability.
Doping is a versatile tool for tailoring the properties of semiconductor thin films. This article investigates the influence of isovalent dopant, Zinc (Zn), on the electronic, optical and structural ...characteristics of copper oxide (CuO) thin films prepared by spray pyrolysis technique. Structural characterization from XRD and Raman studies confirms the successful incorporation of Zn atoms into the CuO lattice without altering monoclinic structure of the films. The absence of secondary phases like Cu2O and ZnO confirms the good quality of the prepared films. A significant variation in the morphology of the films was observed in FESEM images. The EDS analysis confirmed the incorporation of Zn atoms in CuO films and showed that the prepared films are oxygen rich in nature. The band gap of the films increased from 1.50 eV in pristine samples to 1.62 eV in 8 at% Zn-doped sample. Different defect related emissions were observed in PL spectra with the resultant emission in yellowish green region as obtained from chromaticity diagram. XPS analysis confirmed that both Cu and Zn are found in +2 oxidation state. The electrical conductivity and carrier concentration of CuO films improved with doping due to the enhanced oxygen interstitial defects. The carrier density increased from 2.17 × 1014 to 2.82 × 1015 cm−3 after 6 at %doping with the lowest resistivity of 708 Ω cm. Hence, the properties of CuO films can be effectively modified by Zn doping. Zn doping improved the electrical properties of the films without trading off the excellent optical properties of CuO thin films making them suitable in solar cell absorber layer applications.
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•Zn doped CuO films were grown by spray pyrolysis technique.•Spectroscopic analysis confirmed the substitution of the dopant into Cu sites.•Demonstrated that dopant can control oxygen related defects.•Induced defects enhanced electrical properties with minimum perturbation to optical properties.
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Today Perovskite solar cell (PSC) has achieved efficiency close to 26%, surpassing the efficiencies of well- known Dye-Sensitized Solar cells (DSSC), CdTe-based solar cells, etc. Ease ...of preparing perovskite solutions and convenient deposition technique has given them added advantage over other contemporary competitors. This has also made them an economically feasible option. Since the inception of PSCs in 2009, a lot of improvements have been done in various aspects like composition, synthesis technique, fabrication method, and interface study. However, today it is crucial to think about the commercialization of PSCs. In this direction, the stability of PSCs has been a long-standing question. This review focuses on the key aspects of perovskite stability. Challenges posed by environmental factors like moisture, oxygen, temperature, and light are still unanswered. The lead toxicity of PSCs demands a potential substitute of lead with no compromise in their efficiency. The lead-free approach of PSCs and their commercialization has been discussed separately. A suitable emphasis has been given to the encapsulation of solar cells, as we find it a necessary part of the future commercialization process. This review has been addressed with an ideology to provide overall knowledge on the stability issues and challenges concerned with the PSCs, to attract young research community towards this emerging field.
CdSxSe1−x (0 ≤ x ≤ 1) films were deposited on p-Si via thermal co-evaporation method with CdS and CdSe as source materials. The heterostructures were studied for their structural, spectroscopic and ...electrical behaviours by using X-ray diffraction, photoluminescence spectroscopy, low temperature Raman spectroscopy and I-V characterization. Systematic shift in the diffraction peak has confirmed the composition modulation and presence of mixed phase in the ternary CdSSe. Temperature dependent Raman study showed that longitudinal optical modes are shifted to higher wavenumber, which is ascribed to variation in strain and lattice constants with temperature. The diode parameters including ideality factor and barrier height were extracted by applying various models to the temperature dependent I-V measurements. The spectral response of p-Si/CdSxSe1−x (0 ≤ x ≤ 1) were analysed and the heterostructure with x = 0.2 showed high response confirming the device suitability of the heterostructures.
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•Successfully grown CdSxSe1−x (0 ≤ x ≤ 1) films on p-Si by thermal co-evaporation.•P–Si/ CdS0.2Se0.8 heterostructure has shown highest photo response in visible region.•Temperature dependent strain in the heterostructure is validated by low temperature Raman results.
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•ZnTe/CdxZn1-xTe (0.2 ≤ x ≤ 1.0) heterostructure was grown by co-evaporation technique.•Low temperature Raman study revealed the temperature induce strain.•ZnTe/Cd0.8Zn0.2Te showed ...very high photo response in visible range with maximum towards red.•Oxygen incorporation in the films played vital role in photo response.
ZnTe/CdxZn1-xTe (0.2 ≤ x ≤ 1.0) heterostructures were fabricated by thermal evaporation method by using CdTe and ZnTe as source materials. The properties of heterostructures were analysed by X-ray diffraction (XRD), photoluminescence (PL), temperature dependent Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and I-V characterizations. Double diffraction peak in the diffractogram has confirmed bilayer with no or minimum diffusion across the junction. Effect of thermal expansion and an-harmonic coupling to the other phonon modes causing strain induced shift of the longitudinal optical modes were studied through low-temperature Raman spectra. The junction parameters such as barrier height, ideality factor and series resistance were extracted from I - V characteristics by applying various models. ZnTe/CdxZn1-xTe heterostructures having low barrier height and good photo response are explored in this work for the photodetector application. Sample having composition x = 0.8 showed higher response in the visible region with improved response at longer wavelengths.
Doping is one of the easiest methods to enhance the properties of semiconducting thin films. This work presents a systematic study of the influence of Mg doping on the optoelectronic properties of ...copper oxide (CuO) thin films prepared by spray pyrolysis. The pristine and doped films were prepared on glass substrates at an optimized temperature of 350 °C and a precursor solution concentration of 0.15 M while the Mg doping concentration was varied between 2 and 10 at%. The properties of the prepared films were studied in detail by using various characterization techniques such as X-ray diffraction, field emission scanning electron microscopy, Raman and photoluminescence, X-ray photoelectron spectroscopy and Hall measurement. The results suggest that oxygen interstitial (O
i
) defects were enhanced upon doping which has influenced the properties of the film. The size of the crystallites reduced, and the band gap widened after doping. In addition, comprehensive density functional theory analyses have been conducted to gain a thorough understanding of the impact of impurity (
i.e.
, doping/interstitial) atoms on the optical and electrical characteristics of CuO. This study shows that O
i
defects improved the conductivity and enhanced the carrier concentration leading to an improvement in the electrical properties of the films.
Magnesium doping in spray deposited copper oxide thin films enhanced the stable oxygen interstitial defects. It improved the electrical properties while sustaining the favourable optical properties that suit solar cell absorber layer applications.
•Inexpensive food industry by-product was used for lycopene extraction.•Kinetic study was performed very accurately by using ‘continuous measurement’.•Mathematical models were used to understand ...physicochemical behaviour of extraction.•Optimal condition for lycopene extraction is determined.
Lycopene, a nutraceutical compound, was extracted from tomato processing waste, an abundantly available food industry by-product in Italy. The extraction kinetics was mathematically described using the first order kinetic model, the mass transfer model and Peleg’s model to understand the physicochemical behaviour of the extraction. Samples were extracted using acetone/n-hexane mixtures at different ratios (1:3, 2:2 and 3:1, v/v) and at different temperatures (30, 40 and 50°C) and simultaneously analysed using UV–VIS spectrophotometry. The lycopene yield was in the range 3.47–4.03mg/100g, which corresponds to a percentage recovery of 65.22–75.75. All kinetic models gave a good fit to the experimental data, but the best one was Peleg’s model, having the highest RAdj2 and the lowest RMSE, MBE and χ2 values. All the models confirmed that a temperature of 30°C and solvent mixture of acetone/n-hexane 1:3 (v/v) provided optimal conditions for extraction of lycopene.
Abstract Identifying novel cellulose fiber bio-composites has become a vital initiative in the exploration of sustainable materials due to increased global concern for the environment. This growing ...focus on eco-friendly materials has gathered significant attention in recent years. The current investigation deals with one such material, Helicteres isora reinforced Polylactic acid composites. Surface chemical treatment of fiber is one of the most effective methods to modify the hydrophilic fiber to increase its compatibility with the polymer matrix. Sodium hydroxide was used as a pre-treatment chemical to remove any impurities from the fiber surface. Pre-treated fibers were treated with Methacryl silane and Potassium permanganate solution to chemically modify the fiber surface. Density, void content and water absorption behavior of the composites were analyzed as per the standard procedure. Tensile and flexural tests were conducted to evaluate the mechanical strength, modulus, and flexibility of the unidirectional composites. Thermogravimetric and differential thermal analyses were performed to investigate the thermal stability, melting behavior and degradation profiles of prepared composites. A study of failure mechanisms and morphology of the fractured surface through photographs and SEM images revealed fiber splitting and delamination as the dominant reasons behind the failure of composites under tensile loading. Silane-treated Helicteres isora fiber-reinforced Polylactic acid composite exhibited lower water absorption and higher tensile strength than its counterparts. Untreated fiber composite showed maximum flexural strength among the tested composites. By collectively evaluating the results of the tests and properties of the composites, silane-treated fiber-reinforced Polylactic acid composites stands out as the most favorable choice.
Apart from creating an ecological imbalance, drought events could affect an agrarian country's economy and food security by reducing crop yields. The antecedent meteorological droughts could prolong ...into hydrological and (or) agricultural droughts and may co‐exist as concurrent droughts. The current study aims to comprehensively study Indian concurrent droughts, their effects on crop yield, and possible teleconnection with ENSO (El Niño–Southern Oscillation), adopting a copula‐based multivariate approach. The copula functions can replicate the correlation among the variables and keep the dependence structure intact. The concurrent drought characteristics are computed using a multivariate standardized drought index that incorporates the three primary drought indices using the Gaussian copula. Some of the severe concurrent drought years such as 2002, 1987, 1972, and 1965 caused considerable yield losses in Kharif season crops of groundnut, millet, and rice. This prompts to construct quad‐variate models involving the crop yield and the three drought indices using the vine copulas that perform better than the elliptical and symmetric Archimedean copula. Though the isolated forms of droughts could cause mild yield losses, the probability of concurrent droughts causing high to exceptional losses is more. Further, the ENSO teleconnection with the concurrent monsoon droughts is analysed and mapped. The above‐normal warming of the Nino 3.4 region over the tropical Pacific during the months leading up to the monsoon could signal concurrent monsoon droughts in the areas under the Ganga‐Brahmaputra basin at a probability of around 45%. These results could be helpful in drought mitigation measures and policymaking.
Relationships among the drought indices and the crop yield index.
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