UV Absorption Research Articles

Revisiting and Updating the Interaction between Human Serum Albumin and the Non-Steroidal Anti-Inflammatory Drugs Ketoprofen and Ketorolac

Ketoprofen (KTF) and ketorolac (KTL) are among the most primarily used non-steroidal anti-inflammatory drugs (NSAIDs) in humans to alleviate moderate pain and to treat inflammation. Their binding affinity with albumin (the main globular protein responsible for the biodistribution of drugs in the bloodstream) was previously determined by spectroscopy without considering some conventional pitfalls. Thus, the present work updates the biophysical characterization of the interactions of HSA:KTF and HSA:KTL by 1H saturation-transfer difference nuclear magnetic resonance (1H STD-NMR), ultraviolet (UV) absorption, circular dichroism (CD), steady-state, and time-resolved fluorescence spectroscopies combined with in silico calculations. The binding of HSA:NSAIDs is spontaneous, endothermic, and entropically driven, leading to a conformational rearrangement of HSA with a slight decrease in the α-helix content (7.1% to 7.6%). The predominance of the static quenching mechanism (ground-state association) was identified. Thus, both Stern–Volmer quenching constant (KSV) and binding constant (Kb) values enabled the determination of the binding affinity. In this sense, the KSV and Kb values were found in the order of 104 M−1 at human body temperature, indicating moderate binding affinity with differences in the range of 0.7- and 3.4-fold between KTF and KTL, which agree with the previously reported experimental pharmacokinetic profile. According to 1H STD-NMR data combined with in silico calculations, the aromatic groups in relation to the aliphatic moiety of the drugs interact preferentially with HSA into subdomain IIIA (site II) and are stabilized by interactions via hydrogen bonding and hydrophobic forces. In general, the data obtained in this study have been revised and updated in comparison to those previously reported by other authors who did not account for inner filter corrections, spectral backgrounds, or the identification of the primary mathematical approach for determining the binding affinity of HSA:KTF and HSA:KTL.

Newly plant-derived carbon in the deeper vadose zone of a sandy agricultural soil does not stimulate denitrification

Analysis of stable carbon (C) isotopic signatures (δ13C) in various soil C pools provides useful information on soil C sources, transport, and availability. Understanding the extent of deeper soil (below 40 cm) sequestration and transport of plant derived C is of particular interest as this provides a source for microorganisms to drive biological denitrification (as indicated by denitrification enzyme activity, DEA) and hence mitigate the nitrate leaching to groundwater. Meanwhile, studies on deeper soil C sequestration are rare due to methodological constraints. This study was done in deeper vadose zone (0–160 cm) of a sandy agricultural soil in a humid and temperature zone after a C3-C4 vegetation change taking advantage of the marked isotopic differences between C3 and C4 plants. It took place in a site previously grown with C3 crops (beet, barley, grass), but where C4 crops (maize) were grown continuously for the last 20 years. The other site where C3 crops were continuously grown was used for comparison. Specifically, the δ13C signature in top and deeper soil layers was used to distinguish between old C3– and newly C4-plant derived C in four C pools, i.e., bulk soil C, hot- and cold-water extractable C, and respired CO2-C. The δ13C signature between C3 soils and C3-C4 shifted soils was similar for bulk soil C but significantly different for water extractable and respired C pools. Hence, we estimated that the contribution of newly derived C to bulk soil C was negligible, whereas the contributions to the other C pools amounted up to 28.4 % along the soil profile. This emphasizes the importance of simultaneously analysing δ13C signature in various soil C pools to accurately assess C vertical transport and distribution. The concentrations of cold-DOC and values of specific ultraviolet visible absorbance of the wavelengths 254 and 280 nm decreased from 50 to 130 cm soil depths, while they increased below these depths. However, this suggested rise in C chemical quality at the deepest soil depths did not cause an increase in soil respiration activity or DEA, which was attributed to the protective effects of iron and aluminium oxides on C decomposition. Upon the application of labile C and N substrates, the deepest soil layers displayed a significantly increased DEA, suggesting the presence of a relatively abundant population of active denitrifying organisms. Overall, this study documents the presence of plant-derived C in the deeper vadose zone. Meanwhile, this particular C pool might not be an important substrate to drive deep-soil denitrification due to constraints imposed by the protection by metal oxides.

Leaching of organic matter from cigarette butt filters as a potential disinfection by-products precursor

The study aimed to evaluate cigarette butt filters (CBFs) as a potential source of dissolved organic carbon (DOC) in water leading to the formation of disinfection by-products. Two different forms of CBFs – intact (I) and disintegrated (D), as they occur in the environment, were selected for leaching in chlorinated (CI, CD), non-chlorinated (NI, ND), and highly chlorinated (HCD) water samples. The UV absorbance profiles of the leachate samples showed that intact CBFs exhibited higher DOC leaching compared to the disintegrated ones, which was further accentuated in chlorinated samples (CI > CD > NI > ND). The Fourier Transform Infrared spectra of the leachates revealed the presence of characteristic functional groups of cellulose acetate and its chlorinated derivatives, indicating the potential degradation of the polymer. Moreover, trihalomethane (THM) formation in chlorinated samples was relatively higher in CI samples (2 – 11.5 times) compared to CD, consistent with the DOC leaching trends. Further, the speciation characteristics of different THMs in both CI and CD samples were similar. Although spectral and morphological analyzes of CI and CD samples revealed negligible variation, HCD samples depicted significant surface roughness characterized by the formation of pits and holes, along with the evolution of crystallinity. This suggested accelerated degradation of CBFs and disruption of acetyl groups as a factor of elevated chlorine concentrations.

Coumarin-Phosphazenes: Enhanced Photophysical Properties from Hybrid Materials.

Phosphazenes have drawn a great deal of interest over the past 20 years as a potentially useful building block for the fabrication of fluorescent materials. The main objective of this work is to explore novel derivatives produced by coumarins, a class of chemicals well-known for their photophysical importance, and cyclophosphazenes. UV absorbance, fluorescence emission, quantum yield, and lifetime measurements were conducted to comprehend the optical properties. Furthermore, single-crystal X-ray analysis and theoretical calculations were carried out to confirm the structure of the molecule. The obtained findings collectively confirm the commendable optical properties exhibited by the studied compounds. Moreover, a detailed study of the crystal packing arrangement of DPP-Et-Kum-Et compound crystallized in the P21/n monoclinic space group revealed the presence of stacking interactions between the nonplanar conjugated benzene rings of the coumarins and the rigid diphenyl groups attached to the phosphazene ring. The crystal structure of the DPP-Kum-Me-Me compound is mainly based on classical C-H···O intermolecular hydrogen bonding interactions with an average distance of 2.52 Å. Importantly, the calculated absorption spectra of the compounds are in close agreement with the experimental data, further supporting their interesting electronic properties. Given that the DPP-Et-Kum-Et and DPP-Kum-Et compounds have the theoretically lowest band gaps (4.31 and 4.30 eV, respectively), the activation energies of these compounds were determined by an impedance analyzer using dc conductance values measured at different temperatures. The calculated activation energies for DPP-Et-Kum-Et and DPP-Kum-Et are 104.49 and 100.92 meV, respectively. The results demonstrate that both theoretical and experimental calculations are in agreement with each other and that the DPP-Kum-Et compound has the lowest conductivity.

A novel algorithm to extrapolate ultraviolet absorption of chromophoric dissolved organic matter from remote sensing ocean color

Accurate estimation of the absorption of chromophoric dissolved organic matter (CDOM) in ultraviolet (UV) wavelength range is crucial for understanding photochemical and biochemical processes in the global ocean. Here, we propose a novel UV absorption extrapolation (UVAE) algorithm. It extrapolates the absorption coefficients (ag(λ) where λ is the wavelength in nm) of CDOM in the UV wavelength range from ocean color data in the visible wavelength range observed by satellite remote sensing. The extrapolation is based on the assumption that three characteristic Gaussian bands describe the CDOM UV–visible absorption spectra (275–443 nm). The UVAE algorithm retrieves the ag(275), ag(295), ag(330), and ag(380) using the characteristics of the spectral slope (S) of the absorbance spectra of CDOM at specific wavelength intervals, namely 275–295, 295–330, 330–380, and 380–443 nm. With the UVAE algorithm, the spatial variability of CDOM spectral features can be captured on a global scale using data from the Moderate-resolution Imaging Spectroradiometer (MODIS) Aqua mission. The retrieved ag(275), ag(295), ag(330), and ag(380) values match well with in-situ observed values, with mean absolute percent differences (MAPDs) of 19.2 %, 26.1 %, 36.9 %, and 46.6 %, respectively. The performance of the UVAE algorithm demonstrates a significant improvement compared to that of existing algorithms, especially for ag(λ) at lower wavelengths.

Study of the mechanism of non-covalent interactions between chlorogenic acid and soy protein isolate: Multi-spectroscopic, in vitro, and computational docking analyses

This study investigated the interaction mechanism between chlorogenic acid (CA) and soy protein isolate (SPI) through multi-spectroscopic and computational docking and analyzed the changes in its functional properties. The results showed that the interaction of CA with SPI changed its UV and fluorescence absorption, and the fluorescence quenching mechanism was static quenching. At the same time, the secondary structure of the protein was altered, with a reduction in α-helix, β-sheet and β-turn. Computer docking analysis showed that CA binds to SPI through hydrophobic interactions, van der Waals forces, and hydrogen bonding to form a more compact complex. In addition, the dose-dependent enhancement of CA improved the functional properties of the complexes, including foaming, emulsification, and antioxidant properties. This study systematically investigated the mechanism of interaction between CA and SPI, which supports further research on food complex systems containing CA and SPI, as well as the application of the complex.

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.

A ratiometric fluorescent probe for cysteine and glutathione differentiation and its application for cysteine detection in foods

Cysteine (Cys) and glutathione (GSH) are crucial biothiols implicated in cellular redox balance, necessitating accurate detection methods. Herein, we developed a novel fluorescent probe based on the fluorescent dye pyronin (PYR), capable of monitoring both Cys-and GSH using ratiometric fluorescence signals. The probe, named PYR-CG, where "C" stands for Cys-and "G" stands for GSH, demonstrates selective detection capabilities for Cys-and GSH. UV absorption and fluorescence emission spectra changes revealed distinct shifts upon interaction with Cys-and GSH. Theoretical and experimental studies validated PYR-CG's responsiveness to Cys-and GSH, elucidating its mechanism as a ratiometric probe. Notably, PYR-CG exhibited rapid response kinetics for Cys-and GSH, with low detection limits of 88 nM and 164 nM, respectively. Importantly, PYR-CG demonstrated exceptional selectivity for Cys-and GSH over interfering analytes. Screening of molecules with similar structures to Cys-further affirmed PYR-CG's specificity, particularly towards N-terminal Cys-in peptides. Furthermore, recovery experiments underscored PYR-CG's reliability for quantitative Cys-detection in complex food samples. Our findings highlight the innovative design and practical applicability of PYR-CG, offering a valuable tool for sensitive and selective detection of Cys-in diverse biological and food samples.

Electronic and optical properties of COFs/graphene and COF/hBN heterostructures

Covalent organic frameworks (COFs) are a class of intriguing materials with tunable electronic and optical properties. In this work, we investigate the electronic and optical properties of COFs embedded with hBN and graphene. Our results demonstrate that graphene integration enhances the ultraviolet and visible light absorption of C6N6 and B6O6 monolayers, while charge transfer in all COF/graphene heterostructures leads to the formation of a built-in electric field. Furthermore, we show that incorporating hBN into B6O6 and C6N6 heterostructures enables control of their bandgap through an applied electric field, resulting in a semiconductor-to-metal transition under moderate electric field strengths. Additionally, B6O6/hBN exhibits suitable band edge alignment for photocatalytic water splitting. These findings provide valuable insights into the electronic and optical properties of COF heterostructures and their potential applications in electronic and optoelectronic devices. Our study contributes to ongoing efforts in the design and development of novel COF and 2D material heterostructures for future electronic and photonic applications.

First-principles study of oxygen defects in KH2PO4 crystal

This work investigates the electronic structures, defect formation energies and optical properties of charged oxygen vacancy and oxygen interstitial in KH2PO4 (KDP) crystals by First-principles. We find that the lattice distortion caused by VO is greater than that of Oi. For the neutral VO in the ferroelectric (FE) phase, the bond between H and O breaks and re-bonded in VO· system. In VO·· (The superscript represents the charged state, the ‘´’ represents negative charges and ‘·’ represents positive charges), the (PO3)−1 drags the neighboring (PO4)−3 over and bonded with the same O ion. Then it generates a large interstitial position in the structure, which makes it easy to introduce impurity interstitial. Small polaron makes electrons tend to be localized on two or three oxygen ions around the oxygen vacancy. Oxygen defects introduce new defect states in the band gap, which are mainly composed of the p-orbital of O ions. The defect formation energy of VO in two phases and Oi in the FE phase shows negative-U characteristics. Optical spectra indicate that the 467 nm luminescence band originates from the Oi′. The absorption band range from 163 nm to 246 nm is caused by vacancy and range from 212 nm to 428 nm by interstitial. The 200 nm and 285 nm absorption peaks originate from the F-centers (theVO capturing two electrons) and Oi′, respectively. We predict that oxygen defects will introduce additional UV absorption peaks such as 258 nm, 203 nm, 184 nm, and 163 nm, which significantly affect the optical threshold of KDP crystals.

Occurrence of organic ultraviolet absorbers in the particle and gas samples from plastic greenhouses: Human inhalation intake risk assessment

The environmental pollution of organic ultraviolet absorbers (UVAs) has attracted global attention. However, the distribution, sources and risk assessment of UVAs in air from plastic greenhouses are rarely reported. This study was the first to investigate the concentrations of ten UVAs in the air samples from plastic greenhouses. The total concentrations of ten UVAs (∑10UVAs) in the air samples ranged from 5.7 × 103 ng/m3 to 6.3 × 103 ng/m3 (median 5.7 × 103 ng/m3) in greenhouses covered with biodegradable mulch film, 288.2 ng/m3 to 376.4 ng/m3 (median 333.9 ng/m3) in greenhouses covered with PE mulch film, and 97.9 ng/m3 to 142.6 ng/m3 (median 114.9 ng/m3) in greenhouses covered without mulch film. The concentrations of ten UVAs in 65 commercial agricultural films were simultaneously analyzed. Additionally, the potential health risks for greenhouse workers exposed to UVAs were estimated. And the migration simulations showed that the health risk in greenhouses may be higher even if only one UVA is added to the biodegradable mulch film. Therefore, the exposure risk of UVAs in plastic greenhouses needs to be highly prioritized.

Research on COD parameter in water based on the combination of UV absorption photometry and laser spectroscopy

Chemical Oxygen Demand (COD) is widely utilized as a representative and required measurement indicator of water pollution as well as water quality monitoring. The spectral technology is an important development direction in water quality detection. In this paper, a novel COD monitoring instrument is designed based on ultraviolet (UV) absorption photometry and laser spectroscopy. The instrument consists of CODcr and CODmn detection modules. The CODcr module is based on the Lambert-Beer law to measure UV absorption of organic matter in water, which can be used to measure the COD parameter in high concentration organic pollution in water. The CODmn module is based on the ratio method of fluorescence and Raman to analyze the spectral signals generated by the laser-excited water body, which can determine the COD parameter in low contaminated water. By analyzing the CODcr and CODmn parameters together, the comprehensive evaluation of organic pollutants in water can be realized. In the experiment, the CODcr and CODmn modules are respectively calibrated with the potassium hydrogen phthalate (KHP) solution as well as the mixed solution of humic acid sodium and glucose. Then the stabilities of the two detection modules are tested, and the detected result drifts are stable within six days. In addition, to verify the reliability of measuring results in complex environments, we test the instruments at 10 monitoring sites of the Sow River in Weihai city. The results of on-site monitoring are highly consistent with those of national standard method. The study result shows that the instrument developed in this paper can measure both CODcr and CODmn simultaneously, which can expand the COD detection range, and provide a new method for the comprehensive detection of organic pollutants in water.

Predicting the dissolved natural organic matter (DNOM) concentration and the specific ultraviolet absorption (sUVa) index in a browning central European stream

Over the past four decades, an increase in Dissolved Natural Organic Matter (DNOM) and colour, commonly referred to as browning, has been noted in numerous watercourses in the northern hemisphere. Understanding the fluctuations in DNOM quality is a prerequisite for gaining insights into the biogeochemical processes governing DNOM fluxes. Such knowledge is also pivotal for water treatment plants to effectively tailor their strategies for removing DNOM from raw water. The specific ultraviolet absorbance (sUVa) index has been a widely applied measurement for assessing DNOM quality. The sUVa index is the UV absorbance (OD254) of water normalized for DNOM concentration. We have used a long-term dataset spanning from 2007 to 2022, taken from the Malše River in South Bohemia, to model DNOM and the sUVa index. We have applied regression models with a process-oriented perspective and have also considered the influence of climate change. Both DNOM and the sUVa index is positively related to temperature, runoff and pH, and negatively related to ionic strength over the studied period. Two distinct model approaches were employed, both explaining about 40% of the variation in sUVa over the studied period. Based on a moderate IPCC monthly climate scenario, simulations indicate that both DNOM and the sUVa index averages remain fairly stable, with a slight increase in winter season minima projected towards the year 2099. A slight decline in summer season maxima is simulated for DNOM, while the sUVa summer maximum remain stable. These findings suggest a robust resilience in both DNOM and the sUVa index against anticipated changes in temperature and runoff for the Malše River in South Bohemia.

Edible squid ink proteoglycans as a multifunctional sustainable additive for silk coatings: Fire protection, UV shielding and as a colorant

Today, marine biomolecules have attracted great interest in the field of flame-retardant (FR) science due to their sustainability and charring properties. Squid ink is mixed bio-colloid rich in proteoglycans, melanin, and metal ions. Here, squid ink was applied to endow silk with outstanding FR performance and ultraviolet protection through surface coating. After coating with 40 g/L squid ink, silk displayed excellent ultraviolet shielding performance with a high UV protection factor (UPF) of 71.5, attributing to powerful ultraviolet absorption ability of melanin. Besides, the coated silk also exhibited outstanding FR performance, characterized by a shorter char length (7.1 cm) and a higher FR-Index (2.5). The heat release performance of the treated silk dramatically decreased, and the peak heat release rate (pHRR) and heat release capability (HRC) both decreased by 49.1 %. Moreover, a significant reduction in total smoke production (TSP ∼ 60 %) was also observed in cone calorimetry test. A reduction in these fire parameters indicated a great improvement in the fire safety of silk. Interestingly, due to the natural adhesiveness of the proteoglycan mixed colloid, the coated silk could withstand 10 washing cycles while maintaining FR properties. Subsequently, further analyses of the cone residues confirmed the formation of a compact and stable char layer. The squid ink coating exerted an intumescent FR action on silk.

Carrageenan-based functional films hybridized with carbon dots and anthocyanins from rose petals for smart food packaging applications

Multifunctional smart biopolymeric films were fabricated using rose petal anthocyanin (RPA) and carrageenan (CAR) doped with rose petal-derived carbon dots (RP-CDs). Response surface-optimized RPA showed the highest total anthocyanins and radical scavenging ability. Produced RP-CD exhibited UV absorption and high fluorescence with antibacterial/antioxidant abilities. Enrichment with 2 % RP-CD and 5 % RPA in the CAR matrix results in improved physicochemical, i.e., water contact angle, water vapor permeability, and UV-blocking properties of the fabricated material. Results showed that nanocomposite films scavenged radicals better than the neat CAR films. Zeta potential, FTIR, SEM, and XPS suggested improved compatibility/stability and enhanced elemental configuration of RP-CDs/RPA additives in the CAR polymer matrix. Perishable food packaging (minced pork and shrimp) demonstrated that nanocomposite films work efficiently and non-destructively and are promising tools for monitoring real-time freshness through interpretable visual changes from red to yellow. The CAR/RP-CDs/RPA-based nanocomposite indicator films are expected to be applied as various smart packaging materials. These films possess the ability to promptly detect changes in quality, preserve the quality, and prolong the shelf life of packaged foods.

Dual Role of Accretion Disk Winds as X-Ray Obscurers and UV Line Absorbers in AGN

X-ray obscuration of active galactic nuclei (AGNs) is considered in the context of ionized winds of stratified structure launched from accretion disks. We argue that a Compton-thick layer of a large-scale disk wind can obscure continuum X-rays and also lead to broad UV absorption, such as in the blue wing of C iv; the former originates from the inner wind and the latter from the outer wind, as a dual role. Motivated by a number of lines of observational evidence showing strong AGN obscuration phenomena in Seyfert 1 AGNs such as NGC 5548, we demonstrate in this work, by utilizing a physically motivated wind model coupled to post-process radiative transfer calculations, that an extended disk wind under certain physical conditions (e.g., morphology and density) could naturally cause a sufficient obscuration qualitatively consistent with UV/X-ray observations. Predicted UV/X-ray correlation is also presented as a consequence of variable spatial size of the wind in this scenario.

Bergera koenigii stem-derived magnetic biochar nanocomposite for enhanced photocatalytic efficiency of Ce1-xZnxO2-δ NPs under UV light for the degradation of methyl orange

The production of mesoporous, nanocrystalline, Zn-doped CeO2 nanoparticles (NPs) at various concentrations of Zn, Magnetic biochar (MBC)-Zn-doped CeO2 nanocomposites (NC), their characterizations, and photocatalytic degradation analysis are presented in this study. The synthesis of MBC-Ce0.91Zn0.09O2-δ NC is based on the carbonization of an iron oxide precursor with powdered Bergera koenigii stem (curry leaf stem). XRD and TEM results confirm polycrystalline, spherical fluorite Ce1-xZnxO2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC formations. The crystallite size varies from 4–12 nm with an increase in the doping concentration of Zn and 8.55 nm for MBC-Ce0.91Zn0.09O2-δ NC. XPS analysis displays the valence states and surface chemical composition of the as-prepared MBC-Ce0.91Zn0.09O2-δ sample. BET analysis provides the surface area (17–32 m2/g for Ce1-xZnxO2-δ NPs and 142 m2/g for MBC-Ce0.91Zn0.09O2-δ NC) and pore size (25–45 Å for Ce1-xZnxO2-δ NPs and 17.35 Å for MBC-Ce0.91Zn0.09O2-δ NC) of all the samples. All the samples possess good UV absorption in the range of 200–400 nm, and the bandgap energy of the as-prepared samples decreased from 3.088 to 2.79 eV with increased dopant concentration and on-load magnetic biochar. The oxygen deficiencies and lattice deformations of the as-prepared samples are studied using Raman, FTIR, and photoluminescence (PL) spectra. The degradation efficiency of 5 ppm Methyl Orange (MO) is analyzed using 50 mg catalytic (Ce1-xZnxO2-δ NPs, MBC-Ce0.91Zn0.09O2-δ NC) dosage by maintaining the pH of the solution as 4. After 16 min of UV irradiation, the as-synthesized Ce0.91Zn0.09O2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC exhibit 91 % and 97 % decolorization and 90 % and 94 % total organic carbon (TOC) removal efficiency. Regression analysis is performed to evaluate each model's applicability to photocatalytic degradation. The regeneration experiments on Ce0.91Zn0.09O2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC prove the stability of these catalysts for activating MO.

Influence of ZnO and Pr6O11 incorporation on the structural, thermal, optical, mechanical, and magnetic properties of calcium lithium borate glasses

A new glass of calcium lithium borate with the chemical formula (62.75-x)B2O3 + 20CaO + 0.25Pr6O11 + 17Li2O + xZnO, where x = 0, 2.5, 5, 10, 20 (mol%) have been prepared by conventional melt-quenching process. The amorphous character has been confirmed by the very short-range ordering structural matrices demonstrated through X-ray diffraction.The Raman spectra of the prepared glass revealed an enhancement of host lattice distortions. Differential scanning calorimetry (DSC) estimated the glass transition temperature (Tg), the onset temperature of crystallization (Tc), and the melting temperature (Tm). The glass transition decreased from 441 °C to 431 °C with increasing ZnO content up to 10 mol%. The criteria of glass samples up to 10 % ZnO have higher strength, rigidity and higher level of thermal stability. The physical quantities as density, molar volume, inter-atomic distance, polaron radius, packing density, and oxygen packing density were calculated. The glass density increases while the molar volume decreases with ZnO content. The optical properties of glasses were investigated using UV–Vis spectrophotometer. The addition of ZnO enhances the light absorption in UV–Vis. The results of the calculated direct and indirect optical band gaps decrease from 3.663 eV to 3.233 eV for and from 3.167 eV to 2.648 eV for direct and indirect transitions respectively with the increment of ZnO addition. Additionally, the dispersion energy and static refractive index clearly increase while the oscillator energy declines. The Makishima-Mackenzie’s (M−M) method was employed to ascertain mechanical parameters, including elastic moduli, and Poisson’s ratio. The study revealed an enhancement to the mechanical properties as the content of ZnO increased. Vibrating sample magnetometer (VSM) was used to investigate the magnetic properties of the prepared glass and all samples exhibited a ferromagnetic behavior. The incorporation of ZnO act as glass modifier controlling their physical, optical and mechanical properties making the investigated glasses suitable for various applications.

Sorption of colored vs. noncolored organic matter by tidal marsh soils

Abstract. Tidal marshes are significant sources of colored (or chromophoric) dissolved organic carbon (CDOC) to adjacent waters and, as a result, contribute substantially to their optical complexity and ultimately affect their water quality. Despite this, our mechanistic understanding of the processes that regulate the exchange and transformation of CDOC at the tidal marsh–estuarine interface remains limited. We hypothesized that tidal marsh soils regulate this exchange and transformation subject to soil mineralogy and salinity environment. To test this hypothesis, we generated initial mass sorption isotherms of CDOC and noncolored dissolved organic carbon (NCDOC) using anaerobic batch incubations of Great Dismal Swamp DOC with four tidal wetland soils, representing a range of organic carbon content (1.77 ± 0.12 % to 36.2 ± 2.2 %) and across four salinity treatments (0, 10, 20, and 35). CDOC sorption followed Langmuir isotherms that were similar in shape to those of total DOC, but with greater maximum sorption capacity and lower binding affinity. Like isotherms of total DOC, CDOC maximum sorption capacity increased and binding affinity decreased with greater salinity. Initial natively adsorbed colored organic carbon was low and increased with soil organic content. In contrast, NCDOC desorbed under all conditions with desorption increasing linearly with initial CDOC concentration. This suggests that for our test solutions CDOC displaced NCDOC on tidal marsh soils. Parallel factor analysis of 3-D excitation emission matrices and specific ultraviolet absorbance measurements suggested that CDOC sorption was driven primarily by the exchange of highly aromatic humic-like CDOC. Taken together, these results suggest that tidal marsh soils regulate export and composition of CDOC depending on the complex interplay between soil mineralogy, water salinity, and CDOC vs. NCDOC composition.

Dynamic changes in dissolved organic matter during transport of landfill leachate in porous medium.

The dynamic changes in dissolved organic matter (DOM) during the transport of landfill leachate (LL) in porous medium should be explored, considering the high levels of DOM in the LL of municipal solid waste. Column experiments were carried out at 25°C at a Darcy's flux of 0.29cm/h for 2722h to compare the transport of Cl-, ultraviolet absorbance at 254nm (UV254), chemical oxygen demand (COD), and dissolved organic carbon (DOC) in the simulated porous medium by using the CXTFIT2.1 code. Results showed that the convection-dispersion equation (CDE) could describe Cl- transport well. The high levels of λ and D could be highly correlated with the physicochemical properties of the porous medium. The transport of the studied DOM with evident aromatic character could be described appropriately by the CDE model with the first-order reaction assumption, considering the similar variation trends of UV254, COD, and DOC in the effluent during experiments. Specifically, the values of retardation factor (R) were in the following order: DOC > UV254 > COD, whereas the low values of the first-order decay coefficient (k1) for DOC and COD were still higher than that for UV254. High contents of humic-like substances in the DOM with complex toxic components resulted in the natural low removal efficiencies of COD, DOC, and UV254 (≤ 23%), which could be confirmed by the variations of fluorescence index (FI) and humification index (HIX) in the effluent. The results should be helpful in evaluating the environmental risk induced by the LL leakage in a landfill site.