UV Absorption Research Articles

Covalent interaction of ovalbumin with proanthocyanidins improves its thermal stability and antioxidant and emulsifying activity.

The structure of proanthocyanidins (PC) contains a large number of active phenolic hydroxyl groups, which makes it have strong antioxidant capacity. This study investigated the structural and functional properties of ovalbumin (OVA) modified by its interaction with PC. It was found that on increasing the concentration ratio of PC to OVA from 10:1 to 40:1, the free amino and total sulfhydryl contents of OVA decreased from 470.59 ± 38.77 and 29.81 ± 0.31 nmol mg-1 to 96.61 ± 4.55 and 21.22 ± 0.78 nmol mg-1, respectively, and the free sulfhydryl content increased from 7.65 ± 0.41 to 9.48 ± 0.58 nmol mg-1. These results indicated that CN and CS bonds were formed and PC was covalently linked with OVA. The PC content in the OVA-PC conjugates increased from 281.93 ± 12.92 to 828.81 ± 46.09 nmol mg-1 on increasing the concentration ratio of PC to OVA from 10:1 to 40:1. The contents of α-helix and β-turn of OVA decreased, and the contents of β-sheet and random coil increased, confirmed by circular dichroism. The tertiary structure of OVA was also altered according to the results of fluorescence and ultraviolet absorption spectra. The surface hydrophobicity of OVA-PC conjugates decreased with increasing bound polyphenol content. The conjugation of OVA to PC significantly improved its emulsification and antioxidant activity and denaturation temperature. This study may provide valuable information for improving OVA's functional properties and its PC conjugates for applications in the food industry. © 2024 Society of Chemical Industry.

An ultrafast optical sensor for simultaneous detection of NH3 temperature and concentration based on ultraviolet absorption spectral redshift combined with spectral reconstruction

As a renewable and carbon-free fuel with high energy density, ammonia (NH3) is a promising alternative to fossil fuels. Real-time detection of its temperature and concentration is significant in improving NH3 combustion efficiency. In this paper, we report an optical sensor, which enables simultaneous measurement of temperature and concentration of NH3. The key idea is to acquire the temperature of NH3 through absorption spectral redshift, and determine its concentration by building three-dimensional field map combined with spectral reconstruction. Firstly, we explain the generation mechanism of temperature-induced redshift in ultraviolet differential absorption spectrum based on energy level distribution theory. The relationship between spectral redshift and temperature is then established using spectral autocorrelation algorithm. Secondly, a spectral reconstruction method based on absorbed intensity mapping wavelength is proposed to ensure real-time detection of NH3. Finally, a three-dimensional field map between temperature, reconstruction slope, and concentration is constructed to achieve the detection. Results indicated that the mean relative error in temperature measurement was 1.04% and the mean absolute error in concentration detection was 0.26mg/m3 in air. Additionally, the NH3 sensor enabled long-term detection with a detection limit of 15.50μg/m2, demonstrating its potential to broaden the application of NH3 as a fuel.

A thermally stable narrow-band green phosphor Na2MgAl10O17: Eu2+, Mn2+ for NUV LED application

Thermally stable narrow-band green phosphor is important for phosphor-converted light emitting diodes (pc-LEDs). Herein, an efficient and stable Na2MgAl10O17: Eu2+, Mn2+ green phosphor is obtained using Eu2+-Mn2+ energy transfer strategy. The Mn2+ activator could be effectively sensitized by the addition of Eu2+ with significant UV absorption enhancement, then generates a bright green emission with peak at 515 nm and FWHM of 40 nm. The internal and external quantum efficiencies of optimal phosphor Na2MgAl10O17: 0.15Eu2+, 0.50Mn2+ are measured as 69.5 and 30.8 %, respectively. It is found that Na2MgAl10O17: Eu2+, Mn2+ phosphor shows good chemical and thermal stability, i.e. maintains no quenching after H2O/HCl soaking and keeps 90 % of RT intensity at 200 °C. By using Na2MgAl10O17: Eu2+, Mn2+ as converted phosphor, single-chromatic and white pc-LEDs were fabricated, which simultaneously achieve green and white emission with high brightness. Our results show that this Na2MgAl10O17: Eu2+, Mn2+ is a potential candidate as a thermally stable green phosphor for white LEDs.

Fluorescent nectar in non-flying mammal-pollinated plants – observations and considerations in some Asparagaceae

Background and aims – Fluorescence is the emission of light by a fluorophore that has absorbed light of shorter wavelengths. While the role of fluorescence in visual communication has been documented in some animals (budgerigars, gelatinous zooplankton), it is controversially discussed in plants. Floral nectar fluorescence has been mainly found in flowers pollinated by bees. It has been suggested as direct visual cue by which bees can evaluate the available quantity of nectar, thus being important for pollination and foraging efficiency. However, this function has been questioned, since fluorescence is said to be obscured by floral reflections due to low quantum efficiency. The aim of this study was to examine the nectar of plants pollinated by non-flying mammals, namely Eucomis regia, Massonia grandiflora, M. echinata, and M. pustulata (Asparagaceae) from South Africa. Material and methods – To detect possible fluorescence in flowers, the plants were illuminated in a darkened room under UV light and photographed with a camera equipped with a UV/IR cut filter (transmitting at 400–700 nm). Key results – Within the inflorescences, the nectar of all species showed blue to bluish fluorescence and UV absorption. Separated nectar also fluoresced. Conclusion – As fluorescence in flowers occurs not only in bee-pollinated plants but also in plants pollinated by wind, and by nocturnal or crepuscular pollinators (non-flying mammals, bats, moths) for which floral scent is an important attractant, floral fluorescence seems to have no adaptive value for the attraction of flower visitors. We discuss the potential role of fluorescence in flowers as just a by-product of compounds that might have other functions such as visual attraction by reflection (or UV absorbance), protection of genetic material in pollen from UV induced damage, or as a floral filter causing nectar to be bitter, repelling ineffective pollinators but not effective ones.

LLDPE/TiO2 composites with high UV aging resistance and mechanical properties by controlling the alumina coating on TiO2

AbstractFor preparing high performance LLDPE film, the photocatalytic activity and the UV absorption capacity of TiO2 were regulated by the alumina coating content on the surface of TiO2. Alumina‐coated TiO2 was prepared by the chemical liquid deposition method, and characterized by element analysis, TGA, FTIR, and morphology observation. The alumina coating layer had been proven to covalently bind to the surface of TiO2 through AlOTi bonds, which formed a continuous and dense coating layer, followed by forming a loose flocculent coating layer with the increase of alumina content. The alumina coating layer could significantly reduce the formation of carbonyl group on the LLDPE chains, and enhance UV aging resistance of LLDPE by inhibiting the photocatalytic activity of TiO2. Moreover, the dispersion of alumina‐coated TiO2 in the LLDPE matrix was improved. Thus, the transmittance of LLDPE/alumina‐coated TiO2 composites was reduced and the whiteness was improved. Importantly, the continuous and dense alumina coating layer was enough to inhibit the photocatalysis effect of TiO2 on LLDPE. The further increase of alumina coating content reduced the UV absorption capacity of alumina‐coated TiO2 and its compatibility with the LLDPE matrix. Therefore, the best alumina coating content on the surface of TiO2 was 1.46 wt% for preparing high performance LLDPE/TiO2 composites.Highlights Alumina‐coated TiO2 with controllable coating thickness was successfully synthesized. LLDPE/alumina‐coated TiO2 has excellent UV aging resistance and mechanical properties. The photocatalytic activity and UV absorption capacity of TiO2 could be regulated. 1.46 wt% of alumina coating is the best content for high performance LLDPE/TiO2 composites.

An Experimental Dynamic Investigation of the Influence of Melatonin, Serotonin and Tryptophan on the Stability of the DNA Structure

Background: Small molecules play a crucial role in the exploration of physiological pathways and in drug development by targeting deoxyribonucleic acid (DNA). DNA is a central focus for both endogenous and exogenous ligands, which interact directly or indirectly to regulate transcription and replication processes, thus controlling genetic expression in specific cells. Among these molecules, indole derivatives like tryptophan, serotonin, and melatonin are notable for their widespread presence in nature and significant biological effects. Tryptophan, an essential amino acid, serves as a vital structural element in proteins and a precursor for bioactive compounds like serotonin and melatonin, which impact various physiological functions. Methods: Experimental studies have been conducted to reveal the interaction mechanisms of these endogenous indole derivatives with calf thymus DNA (ct-DNA). These investigations involve viscosity measurements and analysis of double-stranded DNA behavior in the presence of indole molecules, using spectrophotometric UV absorption techniques to assess their impact on DNA stability. Additionally, the influence of calcium and magnesium ions on the resulting complexes of these indole derivatives with ct-DNA has been evaluated. Molecular docking validated our findings, offering additional insights into potential DNA–ligand interactions. Utilizing a crystallographic oligomer with an intercalation gap improved docking accuracy, distinguishing intercalation from groove recognition and enhancing assessment precision. Results: Our study offers detailed insights into the interaction patterns of the indole derivatives with DNA and is highly supported by molecular docking analyses: the indole derivatives were predominantly localized between C and G, interacting via π-π interactions and hydrogen bonds and aligning with known data on conventional intercalators. These findings underscore the importance of small compounds’ planar structure and appropriate size, facilitating tight insertion between adjacent base pairs and disrupting regular DNA stacking. Conclusions: Indoles’ physiological roles and potential as drug candidates targeting specific pathways are highlighted, emphasizing their significance as ubiquitous molecules with the ability to modulate biological effects on DNA structure.

Green enrichment of argan oil (Argania spinosa L.) with thyme (Thymus vulgaris L.) and oregano (Origanum vulgare L.) leaves: Evaluating quality and stability improvements

This study aimed to assess the impact of enriching argan oil (AO) (Argania spinosa L.) using the maceration technique with thyme (Thymus vulgaris L.) and oregano (Origanum vulgare L.) leaves (TL and OL) at two proportions (5 and 10%). The oxidative stability of the control and enriched oils was examined under accelerated conditions at a temperature of 60 °C for 120 days (4 months). Quality indices (Free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), ultraviolet absoptions (K232 and K270), Rancimat test, fatty acids composition, sensory attributes, simple phenolic contents (SPC) and antioxidant activity (DPPH•) were determined. As a simple, inexpensive and green method, enrichment by maceration yielded advantageous results. Compared to the control (68.05 ± 1.10 mg GAE/kg), the SPC significantly increased in enriched oils reaching notably 250.9 ± 9.1 mg GAE/kg when adding 10% of TL. Also, the enriched oil samples showed the lowest PV, p-AV and ultraviolet absorptions compared with the control. However, no noticeable changes were reported in fatty acids composition and iodine value. In terms of sensory attributes, enrichment by maceration masked the rancid odour caused by oxidation. These scientific discoveries inherently yield economic advantages by enabling the diversification of product offerings, simultaneously catering to a broader market seeking high-quality oils infused with herbs, including both AO and aromatic plants.

Impact of Different π-Bridges on the Photovoltaic Performance of A-D-D'-D-A Small Molecule-Based Donors.

Three small donor molecule materials (S1, S2, S3) based on dithiophene [2,3-d:2',3'-d']dithiophene [1,2-b:4,5-b']dithiophene (DTBDT) utilized in this study were synthesized using the Vilsmeier-Haack reaction, traditional Stille coupling, and Knoevenagel condensation. Then, a variety of characterization methods were applied to study the differences in optical properties and photovoltaic devices among the three. By synthesizing S2 using a thiophene π-bridge based on S1, the blue shift in ultraviolet absorption can be enhanced, the band gap and energy level can be reduced, the open circuit voltage (VOC) can be increased to 0.75 V using the S2:Y6 device, and a power conversion efficiency (PCE) of 3% can be achieved. Also, after developing the device using Y6, S3 introduced the alkyl chain of thiophene π-bridge to S2, which improved the solubility of tiny donor molecules, achieved the maximum short-circuit current (JSC = 10.59 mA/cm2), filling factor (FF = 49.72%), and PCE (4.25%). Thus, a viable option for future design and synthesis of small donor molecule materials is to incorporate thiophene π-bridges into these materials, along with alkyl chains, in order to enhance the device's morphology and charge transfer behavior.

Degradation of Malachite Green Dye by Solar Irradiation Assisted by TiO2 Biogenic Nanoparticles Using Vaccinium corymbosum Extract

The green synthesis of metal oxide nanoparticles (NPs) offers an alternative to chemical procedures, which can be harmful to human health due to exposure to hazardous substances and harsh synthesis conditions. The following work synthesized titanium dioxide nanoparticles (TiO2 NPs) using a green synthesis method. As a precursor, food-grade TiO2 was used with blueberry extract. This approach makes the process safer, cheaper, and simpler, requiring minimal effort to achieve effective TiO2 NP synthesis. The TiO2 NP characterization was performed by solid-state techniques, such as Ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). According to the XRD diffractograms, TiO2 NPs were obtained in the anatase phase with incidence peaks of 25.28 (101). TEM confirmed their pseudo-spherical shape with an average size of 170 nm. The 3.2 eV bandgap of TiO2 NPs enables UV absorption, making them ideal for efficient photocatalytic degradation under sunlight. On the other hand, the photocatalytic activity of TiO2 NPs was examined using malachite green (MG) dye as a pollutant model under direct sunlight. After 30 min, a degradation of 94% was achieved. The kinetic analysis identified parabolic diffusion and modified-Freundlich kinetics as primary mechanisms, emphasizing diffusion and adsorption in electron transfer. The main reactive oxygen species (ROS) involved in the photodegradation of MG dye were h+ and OH•.

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.

Green synthesis of gold nanoparticles using Pelargonium Graveolens leaf extract: characterization and anti-microbial properties (An in-vitro study)

Background In recent years, there has been a notable increase in the level of attention devoted to exploring capabilities of nanoparticles, specifically gold nanoparticles AuNPs, within context of modern times. AuNPs possess distinct biophysical properties, as a novel avenue as an antibacterial agent targeting Streptococcus Mutans and Candida Albicans. The aim of this study to create a nano-platform that has the potential to be environmentally sustainable, in addition to exhibiting exceptional antimicrobial properties against Streptococcus Mutans as well as Candida Albicans. Methods this study involved utilization of Pelargonium Graveolens leaves extract as a cost effective and environmentally sustainable approach for the green synthesis of AuNPs. Subsequently, physicochemical characteristics were assessed employing a variety of analytical methods, including as transmission electron microscopy, X-ray diffraction, Field Emission Scanning Electron Microscope, Zeta potential, Ultraviolet visible absorption spectroscopy, and Energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The antimicrobial efficacy against Streptococcus Mutans and Candida Albicans was evaluated. Nanoparticles of various shapes, including hexagonal, spherical, semi-spherical, and triangular, were synthesized. These nanoparticles exhibited a mean particle size of 294nm and demonstrated low degree of aggregation. These nanoparticles exhibited long-term stability and were capable of facilely combining with diverse bioactive compounds. Results The study demonstrated that AuNPs which is synthesized by green methods display potent antimicrobial properties. Conclusion Utilization of Pelargonium Graveolens AuNPs may exhibit a promising potential as an antibacterial agent against Streptococcus Mutans and Candida Albicans. Nanoparticles (NPs) have the potential to serve as a novel approach for addressing pathogen infections as well as for biomedical, dental and pharmaceutical purposes in the future.

Exploring the Effects of Optically Active Solvents in Chiral Chromatography on Polysaccharide-Based Columns.

Exploring the effectiveness of optically active solvents as mobile-phase modifiers in chiral liquid chromatography (LC) can offer an additional new tool to tune the chiral selectivity. Hence, the potential of l-ethyl lactate (LEL), a biobased solvent of this nature, was explored for its distinctive interactions with both the mobile phase and analytes, as anticipated from its chiral nature. The findings reveal that LEL provides distinct selectivity compared to commonly used modifiers in chiral LC. Reversed-phase LC (RPLC)-type chiral separations were therefore compared under various conditions whereby LEL was partially or completely replacing common achiral solvents such as acetonitrile (ACN) and methanol (MeOH). An increase in chiral resolution was obtained in 8 of 16 test compounds. For 5 of them a decrease was obtained, and 3 test solutes did not offer satisfactory results under any of the tested conditions on the polysaccharide columns. When LEL was combined with methanol instead of ACN, worse results were obtained, presumably due to its protic nature. Moreover, LEL demonstrates excellent compatibility with salt additives and is fully miscible with aqueous phases. Interestingly, a steeper increase in chiral resolution is observed for LEL, as compared to ACN at lower temperatures. While LEL is somewhat hindered by its higher UV absorbance, it paves the way toward more simplified chiral screening platforms, whereby chiral solutions can be found for fewer columns and greener solvents such as LEL are incorporated. Finally, to elucidate the impact of chiral interactions between the solvent and analytes, the influence of d-ethyl lactate (DEL) was compared with that of LEL. The results revealed different interactions between the stereoisomers of ethyl lactate (EL) and chiral analytes, demonstrating an influence of optically active solvents on enantioseparations.

Assessment and Modeling of Workplace Exposure to Solar Ultraviolet Radiation in Makurdi, Nigeria

Solar radiation though beneficial to life but the harmful effects of over exposure especially in Nigeria has been neglected and its measurement/prediction has received negligible attention in the literature. This study measured and modeled workplace exposure to solar ultraviolet radiation (SUVR) in Makurdi, Benue State, Nigeria. Digital broadband meter was used to measure solar power density in three site while polymer Polysolphone dosimeters were fitted on a human manikin and placed in the sun between 10:00 am- 4:00pm (6 hours) to quantify the amount of Solar UVR absorbed by three occupational workers (Traders, Fishermen and Staff/Students). Five dosimeters were deployed in each of the three sites for calibration to measure UV absorbance in J/m2 while seven in each site were used for body parts. UV/VIS-spectrophotometer was handily used to measure both post and pre-absorbance and the UV exposures were calculated. The UV index was also calculated. Result shows that, head top had the highest exposure values 7.19kJ/m2, 6.51kJ/m2 and 7.00kJ/m2, while the least values was under cloth cover 2.47kJ/m2, 2.08kJ/m2 and 2.20kJ/m2 for traders, fishermen and staff/students respectively. Similarly, the calculated cumulative exposures were 3289.36kJ/m2, 497.82kJ/m2 and 1515.60kJ/m2 at the market square, river bank and the campus respectively. These values were higher than international ICNIRP average value 30J/m2. UV index at market square was 9 (media graphic colour purple), while at river bank and BSU campus was 8 (media graphic colour reddish). High mean irradiant values with high UV index indicates high risk of harm from unprotected sun exposure. Therefore, use of sun protective clothing is recommended and reduce time in the sun especially between 1:00pm and 2:00pm to prevent over exposure that will lead to serious harmful effects especially at the market place.

POSS and PAG Dual-Containing Chemically Amplified Photoresists by RAFT Polymerization for Enhanced Thermal Performance and Acid Diffusion Inhibition

A random copolymer (PTBM), utilized as deep ultra-violet (DUV) photoresist, was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization with tert-butyl methacrylate (tBMA), methyl methacrylate (MMA), triphenylsulfonium p-styrenesulfonate (TPS-SS), and functional poly (sesquicarbonylsiloxanes) (POSS-MA) as the monomer components, and 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl]pentanoic acid (CDSPA) as the RAFT reagent. Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR) proved successful synthesis. Ultraviolet absorption spectroscopy (UV) analysis verified the transparency of the polymer in the DUV band. RAFT polymerization kinetics showed that the polymerization rate conformed to the first-order kinetic relationship, and the polymerization process exhibited a typical controlled free radical polymerization behavior. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and static thermo-mechanical analysis (TMA) showed that the incorporation of POSS groups improved the thermal properties of the copolymer. According to scanning electron microscopy (SEM) images, the copolymerization of photoacid monomers (TPS-SS) resulted in photoresist copolymers exhibiting good resistance to acid diffusion and low roughness.

Optimized reversed phase liquid chromatography methodology for the determination of vonoprazan fumarate impurities: Towards Six Sigma quality standards and sustainability assessment

Vonoprazan fumarate (VPZ), a potent potassium-competitive acid blocker, holds great promise as a therapeutic option for addressing acid-related disorders. This study introduces a refined reversed phase liquid chromatography methodology tailored for the comprehensive analysis of eight related substances, including starting materials, byproducts, and degradants within VPZ. Our approach integrates response surface methodology and tolerance analysis to achieve six sigma quality standards in chromatographic performance. By embedding specifications into the optimization process, we ensure robustness during method development. Chromatographic separation was executed using an XSelect CSH Phenyl-Hexyl column under stepped gradient conditions, employing a mobile phase comprising 0.1 % trifluoroacetic acid aqueous solution and acetonitrile. The flow rate was maintained at 1.3 mL/min, with UV absorbance at 252 nm, and a column temperature set at 25 °C. To evaluate the stability indicating ability of the method, forced degradation studies were conducted. Importantly, identified degradants did not interfere with the accurate quantification of VPZ and its associated impurities. Validation of the method was achieved through accuracy profiles. A greenness assessment was conducted using National Environmental Methods Index (NEMI), carbon footprint analysis, Analytical Greenness Calculator (AGREE), and Complementary Green Analytical Procedure Index (Complex GAPI). Additionally, blueness and whiteness assessments were conducted using the Blue Applicability Grade Index (BAGI) and Red-Green-Blue 12 (RGB 12) algorithms, respectively. The proposed method exhibited a green profile in NEMI and Complex GAPI. The carbon footprint was calculated at 0.055 kg CO2 equivalent per sample. The AGREE score was 0.67, BAGI was 80.0, and the whiteness score from the RGB12 algorithm was 83.5.This methodological framework holds promise for utilization in process development and quality assurance of VPZ in bulk drug manufacturing, particularly in the absence of official monographs within recognized compendia.

Exploring Brominated Aromatic Butenolides from Aspergillus terreus EGF7-0-1 with Their Antifungal Activities.

Fungal diseases could severely harm agricultural productions. To develop new antifungal agents, based on the Global Natural Products Social Molecular Networking, typical bromine isotope peak ratios, and ultraviolet absorptions, cultivation of the soft coral-derived endophytic fungi Aspergillus terreus EGF7-0-1 with NaBr led to the targeted isolation of 14 new brominated aromatic butenolides (1-14) and six known analogues (15-20). Their structures were elucidated by extensive spectroscopic analysis and quantum chemical calculations. Compounds 1-14 exhibited wildly antifungal activities (against Colletotrichum gloeosporioides, Pestalotiopsis microspora, Fusarium oxysporum f. sp. cubense, Botrytis cinerea, and Diaporthe phoenicicola). The bioassay results showed that compounds 1-14 exhibited excellent antifungal activities against C. gloeosporioides, with concentration for 50% of maximal effect (EC50) values from 2.72 to 130.41 nM. The mechanistic study suggests that compound 1 may disrupt nutrient signaling pathways by reducing the levels of metabolites, such as carbohydrates, lipids, and amino acids, leading to an increase in low-density granules and a decrease in high-density granules in the cytoplasm, accompanied by numerous vacuoles, thereby inhibiting the growth of C. gloeosporioides. Monobrominated γ-butenolide 1 may be expected to exploit a novel agriculturally antifungal leading drug. Meanwhile, compound M1 has conformed antifugual activities against C. gloeosporioides by papayas in vivo.

Intensive coagulation of secondary effluent to mitigate reverse osmosis membrane fouling at low temperatures: Strategies of pre-oxidation and coagulant aids addition

Conventional coagulation-sedimentation, typically used as a pretreatment for ultrafiltration-reverse osmosis, is ineffective in solving the problem of reverse osmosis membrane fouling at low temperatures. In this study, the coagulation enhancement effect of pre-oxidation and the addition of coagulant aids on conventional coagulation with polyaluminum chloride as a coagulant was investigated. The results showed that the addition of fly ash, powdered activated carbon, or diatomite as coagulant aids improved the reduction of turbidity, dissolved organic carbon (DOC), and ultraviolet absorbance at 254 nm (UV254), and also reduced the residual content of dissolved aluminum ions. Among them, diatomite was superior. Pre-oxidation before conventional coagulation increased the reduction of turbidity and UV254 by about 50 % and doubled the removal of proteins, polysaccharides, and DOC compared to conventional coagulation. Ozone was superior to sodium hypochlorite. The combination of ozone pre-oxidation and diatomite addition with conventional coagulation further increased the pollutant removal rate, with the removal rates of turbidity, UV254, polysaccharides, proteins, and DOC reaching 82.20 %, 52.35 %, 26.34 %, 24.89 %, and 26.38 %, respectively. In addition, the residual content of dissolved aluminum ions decreased to 0.84 mg/L. The reverse osmosis filtration simulation test showed that pretreating the feed water with the enhanced coagulation by the combination of ozone pre-oxidation and diatomite addition resulted in a slower decrease in membrane flux, reduced foulant content on the membrane surface, and the smallest increase in contact angle. The results of this research may offer a viable pretreatment method to reduce fouling in reverse osmosis membranes operating at low temperatures.

Sustainable design and synthesis of high-performance lignin-based sunscreen ingredients

The active ingredients most commonly employed in sunscreens are compounds containing one or two aromatic rings. Lignin is the most abundant renewable aromatic polymer that has the potential to yield low molecular weight aromatic chemicals when strategically depolymerized. Here, the UV absorbance of a series of monomeric and dimeric lignin model compounds (LMCs) were studied. Specifically, vanillin and ferulic acid demonstrated good absorption in the UVB (280–320 nm) range, while the 5–5 dimer showed efficient absorption in the UVA (320–400 nm) range. Based on this, vanillin, ferulic acid and 5–5 dimer were mixed in pairs and dispersed in the oily isoeugenol to prepare LMC hybrid dispersions. Subsequently, demethylated lignin (DL) was synthesized and used to encapsulate the LMC hybrid dispersions via ultrasonic cavitation to prepare DL-based nano-capsules (DLNCs). The DLNCs were used as the only active ingredient in sunscreens, whose sun protection factor (SPF) value could be up to 55 with a dosage of 10 wt%. Due to anti-photolysis property of DL, the SPF value of DLNCs-based sunscreens increased initially and maintained >8 h under UV irradiation. Additionally, the prepared DLNCs exhibited excellent anti-permeability, antioxidant capacity and biocompatibility, making them a potential substitute for conventional petroleum-based sunscreen agents.

Experimental and numerical study on single ice crystal growth of deionized water and 0.9% NaCl solution under static magnetic field

Ice crystal growth of water and its aqueous solution is the key phenomenon in food freezing. In this research, the effect of static magnetic field (SMF) on single ice crystal growth was investigated combing experiment and simulation. The ice crystal growth of water and NaCl-water solution under 0 - 15 mT SMF intensities were studied. The UV absorbance of water after SMF treatment was measured. Phase field model was adopted to simulate the ice crystal growth. The results show that SMF significantly inhibited the growth rate, while had little effect on the morphology and growth direction of ice crystals. SMF had a certain enhancement effect on the UV absorbance of deionized water. The proposed model could well simulate the ice crystal growth under different SMF intensities. Combining experimental and simulation results, it can be inferred that SMF inhibits ice crystal growth by enhancing original hydrogen bonds and reducing free energy.

An investigation into Venusian atmospheric chemistry based on an open-access photochemistry-transport model at 0–112 km

Atmospheric chemistry plays a crucial role in the evolution of climate habitability on Venus. It has been widely explored by chemistry-transport models, but some characteristics are still poorly interpreted. This study is devoted to developing an open-access chemistry-transport model spanning both the middle and lower atmospheres of Venus. It provides a scheme for the structure of the chemistry, especially for the sulfur and oxygen, and investigates the influence of the cloud diffusivity and the SO2 dissolution that are adopted in the clouds. The developed model is based on the VULCAN framework and was updated with the state-of-the-art Venusian atmospheric chemistry. It includes vertical eddy diffusion retrieved recently with the Venus Express observations, and it resolves radiative transfer containing gas absorption and scattering, Mie scattering of the cloud droplets, and absorption of the unknown UV absorber. The obtained abundance profiles of SO, SO2, CO, COS, O, O2, O3, HCl, and NO are in overall agreement with the observations. The results show that the increase in cloud diffusivity has slight effects on the chemical structure. The SO2 mainly dissolves in 50–90 km and evaporates below the clouds. The rapid dissolution-release cycle is responsible for the large upward flux of SO2 at 58 km. At around 70 km, SO has a significant peak that is larger than that of previous studies by an order of magnitude, and S and SO2 also show slight increases. They are attributed to the buffering effects of liquid SO2 in the clouds. O2 is significantly eliminated by SO in this layer. We emphasize the superior regulation of the sulfur cycle on O2 at 70 km and its potential contributions to the long-standing problem of the overestimated O2 abundance.