UV Absorption Properties Research Articles

Application of Low-Temperature Air Plasma for the Enhancement of Defense Fabric's Self-Cleaning Property.

Self-cleaning textiles have the potential to revolutionize the lives of people like military personnel and hikers who spend extended periods of time in the sun and have restricted access to washing facilities. This research aims to develop the self-cleaning capability of defense uniforms by utilizing air plasma treatment and applying TiO2 nanocoating. Following plasma treatment of differing durations (2, 4, 6, 8, and 10 min, respectively), a pad-dry cure method was employed to apply a TiO2 coating to each sample, while keeping other processing parameters constant. SEM, Fourier transform infrared spectroscopy, ultraviolet protection factor (UVPF), energy-dispersive X-rays, and a water contact angle test were performed in order to validate the air plasma-induced surface modification. There was a gradual escalation in the rate of TiO2 absorption with an extension of the plasma treatment duration. Afterward, the samples were stained with various organic and inorganic compounds, including oil, ink, soil, and coffee, and subsequently exposed to sunlight for a period of 6 h. The samples demonstrated an enhanced cleaning effectiveness with increasing quantities of TiO2. The reflectance value and visual assessment of washed sample showed a reduced yet still present self-cleaning characteristic. The UVPF of the samples increased gradually as the duration of plasma treatment increased due to the UV absorption properties of TiO2, as validated by measuring the band gap energy.

Mechanical and Electronic properties of ZnIV1-xIVxN2 (IV=Si, Ge and Sn) with varied concentrations: First-principles calculations

This study employed first-principles calculations to explore the mechanical and electronic properties of ZnIV1-xIVxN2 (IV=Si, Ge, Sn) at varying concentrations. Adding Si enhances elasticity, brittleness, and hardness by reinforcing Zn/IV-N ionic bonding, while Sn addition diminishes these properties. Electronic band structures indicate that antibonding states mostly arise from IV p orbitals hybridized with N s orbitals, impacting energy bandgaps. Bader charge analysis confirms enhanced ionic bonding with Si addition and weakened bonding with Sn, consistent with IV ion sizes and charges influencing bond lengths and hybridization strengths. Our study suggests that the ductility of ZnIVN2 can be improved while maintaining its UV absorption properties by using ZnGe1-xSixN2 with x = 0.25,0.50 and ZnSi1-xSnxN2 with x = 0.25, which is dynamically stable. These compounds exhibit energy gaps of 3.29–3.83 eV and 3.52 eV, respectively. In ZnGe1-xSixN2, the energy gap ranges from 4.62 to 2.82 eV, while in ZnGe1-xSnxN2, it spans from 1.16 to 2.82 eV. For ZnSi1-xSnxN2, the energy gap extends from 4.62 to 1.16 eV. The Sn p + N s hybridization is weakest compared to the Ge p + N s and Si p + N s hybridizations, respectively, resulting in a lower energy antibonding state for ZnSnN2 > ZnGeN2 > ZnSiN2. This leads to the observed bandgap differences.

Molecular weight fraction-specific transformation of natural organic matter during hydroxyl radical and sulfate radical oxidation

Aquatic natural organic matter (NOM) is one of the main scavengers of reactive species (e.g., •OH and SO4•−) during oxidation processes and undergoes complex transformations. Here, the organic content, optical properties, and redox state in various MW fractions and bulk Suwannee River NOM (SRNOM) were simultaneously evaluated during •OH and SO4•− oxidation processes for the first time. The SRNOM transformation pathways were specific to radical species and MW fractions, which was evidenced by a proportional decrease in electron-donating moieties and chromophores during •OH oxidation but a higher decrease in electron-donating moieties than chromophores during SO4•− oxidation, particularly in lower MW fractions (<3 kDa). The •OH decomposed reactive moieties mainly via aromatic ring opening or depolymerization in all MW fractions. SO4•− oxidation followed a similar pathway in higher MW fractions (>3 kDa) but mainly formed compounds with UV-absorbing properties (e.g., quinones) in lower MW fractions (<3 kDa). With competitive kinetics and depolymerization model, •OH was quantified as approximately 10 times more reactive towards MW fractions than SO4•−. However, the SO4•− concentrations were approximately 10 times those of •OH, resulting in comparable performance to •OH oxidation. SRNOM depolymerization by •OH and SO4•− resulted in formation of more precursors of disinfection byproducts than the parent constituents, especially for •OH. This work improves our understanding of the transformation of specific SRNOM fractions during radical oxidation processes.

New theoretical insights on the nonradiative relaxation mechanism of the core structure of mycosporines: The amino-cyclohexenone central template.

We present a comprehensive computational study describing the excited state dynamics and consequent photostability of amino-cyclohexenone (ACyO), the central template of mycosporine systems, widely recognized for their photoprotection of aquatic species. Photoexcitation to the first excited electronic state (S1, 1nπ*) of ACyO is considered an optically dark transition, while photoexcitation to the second excited electronic state (S21ππ*) is an optically bright 1ππ* transition and largely responsible for UV absorption properties of this molecule. We show that following initial photoexcitation to S2, ACyO relaxes via two competing deactivation mechanisms, each mediated by an S1/S0 conical intersection, which directs the excited state population to the electronic ground state (S0). Our abinitio computational results are supported with nonadiabatic dynamics simulation results, yielding an excited state lifetime of ∼280fs for this system in vacuo. These results explain the inherent photostability of this core structure, commonplace in a wide range of microorganisms.

Formation of Bismuth Doped Cerium Oxide Nanopowder with Thermal Stability and UV Absorption Properties

Formation of Bismuth Doped Cerium Oxide Nanopowder with Thermal Stability and UV Absorption Properties

Biofilm-forming bacteria associated with corals secrete melanin with UV-absorption properties.

Corals are colonized by a plethora of microorganisms, and their diversity plays a significant role in the health and resilience of corals when they face oxidative stress leading to bleaching. In the current study, we examined 238 bacteria isolated from five different coral species (Acropora hyacinthus, Pocillopora damicornis, Podabacea crustacea, Porites lobata, and Pavona venosa) collected from the coral reef ecosystems of Kavaratti, Lakshadweep Islands, India. We found that bacteria such as Psychrobacter sp., Halomonas sp., Kushneria sp., Staphylococcus sp., Bacillus sp., Brachybacterium sp., Citrobacter sp., and Salinicola sp. were commonly present in the corals. On the other hand, Qipengyuania sp., Faucicola sp., Marihabitans sp., Azomonas sp., Atlantibacter sp., Cedecea sp., Krasalinikoviella sp., and Aidingimonas sp. were not previously reported from the corals. Among the bacterial isolates, a significant number showed high levels of biofilm formation (118), UV absorption (119), and melanin production (127). Considering these properties, we have identified a combination of seven bacteria from the genera Halomonas sp., Psychrobacter sp., Krasalinikoviella sp., and Micrococcus sp. as a potential probiotic consortium for protecting corals from oxidative stress. Overall, this study provides valuable insights into the coral microbiome and opens up possibilities for microbiome-based interventions to protect these crucial ecosystems in the face of global environmental challenges.

Environmentally Friendly UV Absorbers: Synthetic Characterization and Biosecurity Studies of the Host-Guest Supramolecular Complex.

Isoamyl 4-methoxycinnamate (IMC) is widely used in various fields because of its exceptional UV-filter properties. However, due to its cytotoxicity and anti-microbial degradability, the potential eco-environmental toxicity of IMC has become a focus of attention. In this study, we propose a host-guest supramolecule approach to enhance the functionality of IMC, resulting in a more environmentally friendly and high-performance materials. Sulfobutyl-β-cyclodextrin sodium salt (SBE-β-CD) was used as the host molecule. IMC-SBE-β-CD supramolecular substances were prepared through the "saturated solution method", and their properties and biosecurity were evaluated. Meanwhile, we conducted the AOS tree evaluation system that surpasses existing evaluation approaches based on apoptosis, oxidative stress system, and signaling pathways to investigate the toxicological mechanisms of IMC-SBE-β-CD within human hepatoma SMMC-7721 cells as model organisms. The AOS tree evaluation system aims to offer the comprehensive analysis of the cytotoxic effects of IMC-SBE-β-CD. Our findings showed that IMC-SBE-β-CD had an encapsulation rate of 84.45% and optimal stability at 30 °C. Further, IMC-SBE-β-CD promoted cell growth and reproduction without compromising the integrity of mitochondria and nucleus or disrupting oxidative stress and apoptosis-related pathways. Compared to IMC, IMC-SBE-β-CD is biologically safe and has improved water solubility with the UV absorption property maintained. Our study provides the foundation for the encapsulation of hydrophobic, low-toxicity organic compounds using cyclodextrins and offers valuable insights for future research in this field.

Luminescent triazolo-fused pyrido[3,4-b]pyrazines as novel fluorophores

A series of organic fluorophores based on novel [1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine architecture were synthesized by a simple two-step protocol. Synthesized organic fluorophores exhibit blue-to-green fluorescence and their UV absorption and fluorescent emission properties were studied. The photophysical properties of synthesized derivatives were tuned by introducing functionalities of varying electronic nature on the core nucleus. The luminescence maxima of the synthesized compounds are found in the range from 427 nm to 503 nm, and the quantum yields ranging from 0.01 to 0.64 were calculated. Among various synthesized molecules, 3-(4-bromophenyl)-8,9-bis(4-methoxyphenyl)-[1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine showed highest quantum yield (ΦF = 0.64), and was further explored for its solvatochromic, acidochromic, aggregation induced fluorescence studies along with theoretical HOMO-LUMO calculations.

Substituent effects in 2-hydroxybenzophenone-based ultraviolet absorbers

2-Hydroxybenzophenone is the simplest molecule among benzophenone-based UV absorbers. Changing the position and type of substituents affects the strength of intramolecular hydrogen bonding and thus modulates the UV absorption properties. In this work, 132 2-hydroxybenzophenone-based UV absorbers with different substituent positions and species were designed to investigate the substituent effect in their UV absorption properties. The results show that when the substituent positions are the same, the characteristic peaks of the compounds containing substituents of the same group of atoms or homologous groups correspond to similar wavelengths. When the substituent groups are the same, the wavelength redshift of the characteristic peaks of the UV absorption spectra of the compounds of the NX and NZ classes is more pronounced than that of the remaining species, and the substituent group containing N atoms causes the molecule to have a more pronounced wavelength redshift. The redshift of the characteristic absorption peaks corresponding to the wavelengths decreases with the increase of the energy level difference. Atoms-in-molecules (AIM) analysis showed that the electron-absorbing group in the compound enhances the hydrogen bond strength to a lesser extent than the electron-donating group. Natural Bond Orbital (NBO) analysis further revealed that the type and position of the substituent groups in the molecular structure influenced the strength of the intramolecular hydrogen bonding by affecting the distribution of the charges among individual atoms in the 2-hydroxybenzophenone molecules. This work aims to reveal the effect of substituents on the UV absorption properties of 2-hydroxybenzophenone-based molecules and to provide theoretical guidance for the design of such UV absorber molecules absorbing UV light at specific wavelengths.

Optical behaviour of magnetron sputtered nano-hilled TiN coatings

Cylindrical magnetron sputtered TiN thin films have been grown on glass (G) and quartz (Q) substrates to examine optical properties under two flow conditions: increasing nitrogen flow rate (1 → 35 sccm): (I) and decreasing nitrogen flow rate (35 → 1 sccm): (D). The optical properties of the film are characterized using UV–Vis-NiR spectroscopy, spectroscopic ellipsometry, and photoluminescence studies. Films deposited under both parameters exhibited excellent UV-restriction properties. Nano-hilled topography of the film contributed to multiple reflections and scattering of incident light on both quartz and glass specimens. Clustering of nano-particles in G(D) specimen increases the light interaction and absorption within the film leading to higher absorbance and lower transmittance properties compared to G(I). TiN-Quartz specimen displayed better UV absorbing properties compared to TiN-Glass as confirmed through ellipsometry studies. lack of phonon-related transitions in Tauc's plot indicated the involvement of direct allowed transitions.

Long-term quantification of springtime aerosols over Saudi Arabia using multi-satellite remotely sensed data.

A comprehensive analysis of aerosol characteristics over Saudi Arabia from 2005 to 2022, utilizing high-resolution satellite-based observations and reanalysis datasets, examining the distribution of aerosols and their subtypes across the three dimensions (temporal, spatial, and altitude based) for March, April, and May. This study focuses on the analysis of parameters such as aerosol optical depth (AOD), angstrom exponent (AE), absorption aerosol optical depth (AAOD), and Ultraviolet Aerosol Index (UVAI), revealing significant spatial disparities, with elevated aerosol concentrations in the central and eastern regions and comparatively lower concentrations along the western coastal areas. In this study, the spatial patterns and temporal trends are analyzed through trajectory modeling. The study also investigates the composition of aerosols in various Saudi cities. Aerosols prevailing in a dozen Saudi Arabian cities were systematically categorized into six sub-types, considering their particle size and UV-absorbing properties. Notably, two major aerosol sub-types, absorbing coarse (AC) aerosols (UVAI > 0.25, AE < 0.70) treated as mineral dust and absorbing mixed (AM) aerosols (0.70 < AE < 1.25) along with neutral fine (NF) particles (- 0.5 < UVAI < 0.25, AE > 1.25) treated as urban, predominate across the Kingdom of Saudi Arabia.

A low-molecular-weight, long-wavelength emissive Coumarin: Green synthesis, spectral properties, fluorescence enhancement and solvatochromism application

In this study, a novel low-molecular-weight coumarin fluorescent dye, 3,4-dicyano-7-diethylaminocoumarin, was designed. This dye features a donor-π-bridge-acceptor (D-π-A) conjugated structure, which confers superior fluorescence properties.The dye was synthesized using a simple, efficient, and environmentally friendly two-step process, facilitating the direct conversion of the key intermediate into the final product via simultaneous addition and elimination reactions. A comprehensive structural characterization of the dye was undertaken, and its UV absorption and fluorescence emission properties were extensively analyzed using spectroscopic techniques, with structural explanations of the fluorescence activities provided by the Density Functional Theory (DFT) method.Experimental results revealed that this coumarin dye emits strong fluorescence, characterized by a long wavelength, a large Stokes shift, and high fluorescence intensity. It exhibits excellent fluorescent performance in various solvents. Despite experiencing fluorescence quenching in its solid state, the formation of an inclusion complex with β-cyclodextrin restores strong red fluorescence, presenting new possibilities for biofluorescence imaging. Notably, this coumarin dye also demonstrates a significant solvatochromic effect. This effect enables rapid visual discrimination among multiple sets of structurally and chemically similar organic solvents. Consequently, the dye holds promise as a versatile solvatochromic fluorescent probe for a broad spectrum of applications.

Oleaeuropaea leaf exosome-like nanovesicles encapsulated in a hyaluronic acid / tannic acid hydrogel dressing with dual “defense-repair” effects for treating skin photoaging

Photoaging, primarily caused by ultraviolet (UV) light, is the major factor in extrinsic skin aging. Existing anti-photoaging strategies mainly focus on early sun protection or repairing damaged skin, lacking a comprehensive treatment strategy. Therefore, this study developed a dressing that actively shields against UV radiation and repairs photoaged skin, offering double protection. This study utilized exosome-like nanovesicles derived from Olea europaea leaves (OLELNVs), enhancing them into a potent core biomaterial with high-dose effects and skin-friendly, non-cytotoxic inhibition of cell aging. These nanovesicles were incorporated into a cross-linked hyaluronic acid (HA) and tannic acid (TA) hydrogel with strong UV-absorbing properties, creating the OLELNVs@HA/TA hydrogel system. In vitro and in vivo experiments demonstrated that OLELNVs@HA/TA hydrogel can effectively reduce UV-induced skin damage and promote skin repair and regeneration. Additionally, RNA-seq and clustering analysis of miR168a-5p predicted targets revealed significant down-regulation of the NF-κB signaling pathway, mediating inflammatory aging responses. Overall, the OLELNVs@HA/TA hydrogel represents a novel dual-strategy approach for clinical application in combating photoaging.

Changes in antioxidant properties of pepper leaves (Capsicum annuum L.) upon UV radiation

Bell pepper (Capsicum annuum) is one of the most popular vegetables consumed worldwide. The leaves of pepper are rich in phenolics, including phenolic acids and flavonoids. These compounds are well known for their ultraviolet (UV) absorbing and antioxidant properties. While the change of the phenolic pattern is an intensive research subject, it is not yet well-known in pepper leaves, particularly in outdoor conditions. In this experiment, we examined the effect of UV radiation on the leaves of outdoor grown peppers, focusing on the UV-absorbing properties and antioxidant capacities. Three different total antioxidant capacity (TAC) measurements have been compared: (I) Folin-Ciocalteu Reactivity (FC), (II) Ferric Reducing Antioxidant Power (FRAP) and (III) Trolox Equivalent Antioxidant Capacity (TEAC). Moreover, non-enzymatic hydrogen peroxide scavenging antioxidant capacity was measured. Significant increase was detected only in FRAP, suggesting an elevation exclusively in the level of phenolic acids in case of UV exposed outdoor grown pepper leaves.

Ex vivo UV-C Protective Effect of Aloe vera

Chronic exposure to UV-C can cause sunburn, skin cancer, oxidative stress as well as photo-aging. Many herbs and plant extracts have recently been recognized as a potential source of sunscreen due to their UV-absorbing properties. Aloe vera L., which has been used for therapeutic purposes by humans for centuries, is also among these plants. In this study, it was aimed to reveal the sunscreen properties of the latex and gel parts of A. vera and the effect of these properties on cells exposed to UV rays. In this study, primarily, the lethal effect of UV-C rays on healthy cells was observed over time. Then, the latex and gel parts of the obtained A. vera plant were separated and spread on the surface of petri dishes as a single and double layer. By adding a determined number of cells of the petri dishes, the protection of A. vera against the lethal effect of 1, 1.5 and 2 hours of UV-C exposure was investigated. According to the study findings, it was determined that both parts of A. vera protect cells against UV-C damage. It is quite remarkable that while all the cells in the control group died as a result of UV-C exposure for 2 hours, vitality was still observed in the double layer latex and gel groups. From this point of view, it has been shown in this study that a protective product that can be made using A. vera can prevent the damages that may develop due to UV-C exposure.

Smart fluorescent PVA/CS/AV/g-C3N4QDs hydrogel nanocomposites: synthesis and study of UV absorbance, rheological and self-healing properties

Response to exterior stimulants, such as light and pH and also self-healing behavior are the major specifications of smart nanocomposites. This project aims to synthesise various weight percentages of smart fluorescent hydrogel nanocomposites using natural and bio-friendly materials including polyvinyl alcohol (PVA), corn starch (CS), aloe vera (AV) and g-C3N4QDs (PSA/CN). Graphitic carbon nitride quantum dots (g-C3N4QDs or CN) were synthesised by way of pyrolysis of the urea and citric acid (CA) blend with 18:1 weight proportion employing microwave-supported procedure. Next, synthesis and properties of the prepared nanocomposites were verified by means of microscopic and electroscopic methods. The strong absorption peaks registered at 230, 290 and 390 nm confirmed UV absorption ability of the synthesised PSA/CN nanocomposites. In response to 390 nm exciting wavelength, these nanocomposites emitted green fluorescence (FL) at 505–510 nm. Adding CN (0.25 wt% and 0.5 wt%) to the hydrogel matrix bred a growth in thermal stability of the resultant nanocomposites. Loading diverse weight percentages of CN into hydrogel matrix led the rheological features of the hydrogel nanocomposites to improve. Studies on pH-responsive and rheological analyses approved self-healing behavior of the PSA/CN nanocomposites against damages.

Evaluation of MAA Analogues as Potential Candidates to Increase Photostability in Sunscreen Formulations

Avobenzone is one of the most widely used sunscreens in skin care formulations, but suffers from some drawbacks, including photo instability. To mitigate this critical issue, the use of octocrylene as a stabilizer is a common approach in these products. However, octocrylene has been recently demonstrated to show potential phototoxicity. The aim of this work is to analyze the performance of a series of mycosporine-like amino acid (MAA)-inspired compounds to act as avobenzone stabilizers as an alternative to octocrylene. Different avobenzone/MAA analogue combinations included in galenic formulations were followed under increasing doses of solar-simulated UV radiation. Some of the synthetic MAA analogues analyzed were able to increase by up to two times the UV dose required for 50% of avobenzone photobleaching. We propose some of these MAA analogues as new candidates to act as avobenzone-stabilizing compounds in addition to their UV absorbance and antioxidant properties, together with a facile synthesis.

Simple preparation of UV-absorbing and magnetic superhydrophobic membranes by one-step electrospinning for effective oil–water separation

Developing multifunctional separation membranes, especially composite separation membranes that are corrosion-resistant, fouling-resistant, and easy to collect, has become a new challenge to treating oily wastewater in complex environments. Therefore, superhydrophobic magnetic membranes composed of polystyrene/poly(acrylonitrile)-poly(vinylidene fluoride)/poly(dimethylsiloxane)-iron oxide/titanium dioxide nanoparticles (PS/PAN-PVDF/PDMS@Fe3O4/TiO2), which possess exceptional corrosion resistance and UV absorption properties, were fabricated through the process of electrospinning. Controlling the doping ratio of Fe3O4/TiO2, composite membranes with excellent superhydrophobicity (156.9°), mechanical properties (3.67 MPa and 75.93 %), and thermal stability (330 °C) were obtained. The membrane demonstrates outstanding corrosion resistance (WCA > 150°) even after being immersed in various corrosive solutions for 120 h. Under visible-ultraviolet irradiation, the membrane has excellent UV absorption and exhibits a significant red-shift phenomenon, providing a certain degree of resistance to fouling. In the presence of a magnetic field, the membrane has a maximum saturation magnetization of 9.98 emu/g, which the magnetic field drive can attract. The oil adsorption capacity of the membrane was 29–112 g/g, which also maintained 88 % of the initial value after ten cycles. In addition, a comprehensive evaluation was conducted to assess the fabricated composite membrane's separation flux, efficiency, and cycle life when exposed to acidic and alkaline corrosive solutions. The results indicated that even after 40 cycles, the membrane's oil–water separation flux and separation efficiency remained at 6971 L.h−1.m−2 and 97 %, respectively, representing a 24.2 % increase compared to the unmodified membrane. Therefore, the membrane exhibits promising potential for treating oily wastewater in harsh environments.

Preparation and application of high thermal conductivity phase change microcapsules with fluorescence characteristics based on a ZnWO4 shell.

Phase change microcapsules (NePCMs) with high latent heat values, thermal conductivity and stability were synthesized by coating stearic acid (SA) phase change materials (PCMs) with zinc tungstate (ZnWO4) as the shell material. The prepared ZnWO4 and microcapsule samples are characterized through various techniques, and their thermophysical properties under different core-shell ratios and emulsifiers are compared. The highest value that the phase transition enthalpy reaches is 83.63 J g-1 when the core-shell ratio is 1 : 1 and sodium dodecylbenzenesulfonate (SDBS) is adopted as the emulsifier. Based on SEM and TEM results, the regular spherical shape and the complete core-shell structure of the microcapsule can be found, and the particle size ranges between 100 and 300 nm. The thermal conductivity of SA increased by 141.18%-238.43% after using ZnWO4 as the shell material. Moreover, thermogravimetric and leak-proof performance tests demonstrated that microcapsule samples possess high thermal stability. There was no leakage from the six microcapsule samples after heating, proving their potential application in thermal energy storage (TES) under long-term high-temperature conditions. In addition, the cost of ZnWO4 prepared by this method can be reduced by about 40%. According to UV absorption and fluorescence spectrum evaluation, ZnWO4 and microcapsule samples exhibit good photoluminescence and UV absorption properties, indicating that the sample can be widely employed in fluorescent construction, coatings and textile industries at a lower cost.

Green synthesis of insecticidal, bactericidal, UV absorbent, sustainable paint formulations using Mentha piperita (peppermint)

The present study aims to develop a natural insect-repellent paint formulation derived from plant-based materials with UV absorption and antibacterial properties.