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As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size. [ABSTRACT FROM AUTHOR]

Herein, we loaded cobalt-based zeolite imidazolate frameworks, ZIF-67 (Co), onto commercial filter paper to prepare catalytic filter paper (ZFP) for the in situ degradation of bisphenol A (BPA) in water by activating peroxymonosulfate. The results showed that ZIF-67 (Co) was densely and uniformly distributed on the surface of the filter paper. The prepared ZFP could effectively degrade BPA in situ through a gravity-driven filtration process. Specifically, when the flow rate of the BPA solution passing through ZFP was lower than 10 mL/min, 0.02 mM of BPA could be completely degraded by ZFP. Furthermore, ZFP showed promising water matrix adaptability, which could provide promising BPA degradation efficiency in a wide pH range or in the existence of multiple anions. The scavenging tests demonstrated that both sulfate radical and hydroxyl radical were generated for BPA degradation, in which hydroxyl radical was the dominant active species. The ZFP also exhibited promising long-time use stability with a high mineralization rate. This study provides a novel method to prepare high-efficient catalyst paper for the in situ organic pollutant removal in water media via a prompt filtration process. [ABSTRACT FROM AUTHOR]

Paper spray ionization mass spectrometry (PSI MS) has emerged as a notable method for the rapid analysis of biological samples. However, the typical cellulose-based paper tip is incompatible with protein detection due to the strong interaction between cellulose hydroxyl groups and proteins. In this study, we utilized a commercially available polyolefin-based synthetic paper, Teslin®, as an alternative PSI substrate for simple protein analysis. We have named this method "droplet PSI" MS, as the aqueous protein solution droplet retains its shape on the Teslin® paper tip. For droplet PSI, no further chemical pretreatment was necessary for the Teslin® substrate; the only required preparation was shaping the Teslin® paper into a triangular tip. In droplet PSI MS, protein ion signals were instantly detected from a protein solution droplet upon applying a spray solvent in situ along with high voltage (HV). When compared with conventional PSI MS, our method demonstrated superior sensitivity. The droplet PSI MS utilizing Teslin® also showcased flexibility in real-time observation of protein alterations induced by an acid additive. Additionally, the effects of spray solvent composition and the application method were discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimization study of Photo-Fenton and PDS/UV processes for BOD and COD removal. • Photo-Fenton process was able to enhance biodegradability. • PDS/UV process on the best condition only could maintain the biodegradability. • The operational cost of Photo-Fenton processes is much cheaper than PDS/UV process. The aim of this study is to provide an Advanced Oxidation Process (AOP) based solution to enhance biological treatment efficiency by improving biodegradability of wastewater. Photo-Fenton and Peroxydisulfate (PDS)/UV processes were selected in this study as a representative of hydroxyl and sulfate radical based AOPs. A central composition design (CCD) employed to optimize operational cost and BOD/COD ratio to determine optimal conditions for enhancing wastewater treatment efficiency. The study achieved a maximum COD removal of 71.5 % and increased wastewater biodegradability. Optimal conditions for Photo-Fenton process were DOD (H 2 O 2) 0.28, [Fe2+] 106.26 mg/L, and pH 2.32, costing 2.27 USD per 1 kg COD removed. For PDS/UV process, 75.5 % COD removal was achieved at a cost of 10.6 USD/1 kg removed COD. The PDS/UV process had higher COD removal than Photo-Fenton but did not improve wastewater biodegradability. Optimal conditions were DOD (PDS) 0.19, pH 6.68, costing 10.6 USD/1 kg COD removed. [ABSTRACT FROM AUTHOR]

It is of great importance to protect paper cultural relics, especially in terms of making them waterproof. One of the important ways to protect paper cultural relics is by hydrophobic modification treatment. However, most of the existing hydrophobic modification methods rely on a great deal of organic solvents, which poses greater risks to safety and pollution. In this work, a simple, green, and effective method for paper hydrophobic treatment was proposed and evaluated. The vapor of a fluorinated triethoxysilane was reacted with the active hydroxyl group on the paper in a closed space, which realized the hydrophobic modification of the paper in one step. The contact angle of the hydrophobic paper prepared by this method was 148.4° under optimal experimental conditions. In addition, this method did not damage the paper, based on the results of the scanning electron microscopy of the paper before and after hydrophobic treatment. The generality of this method was verified by using other substrates and hydrophobic reagents. This method is simple to operate and does not require the usage of a large amount of organic reagent. It is expected to receive widespread attention in the field of the protection of paper and wooden cultural relics. [ABSTRACT FROM AUTHOR]

The paper aging is primarily attributed to the presence of carbonyl groups formed as a result of the oxidation of the hydroxyl groups at the second and third carbon atom in the elementary unit of the cellulose macromolecule and the presence of both aldehyde and carboxyl groups in the cellulose materials. Reduction of paper whiteness degree is mainly connected with the presence of lignin, hemicelluloses, the presence of metals and the sizing agent type. The paper as an elasto-plastic, capillary porous material quickly breaks down at an elevated temperature. The latter accelerates the chemical reactions that occur in paper in the course of aging. The depth of the paper changes depends not only on the temperature but also on the duration of the impact. For different paper types differing in composition the reaction rate constant is different. Its temperature dependence is described by the Arenius equation. The aim of this work is to carry out a kinetic analysis of the influence of the temperature increase on the ageing of coated paper used for book covers. The accelerated thermal aging is conducted at three different temperatures - 90°C, 105°C and 120°C with duration of 6 h, 12 h, 18 h, 36 h and 48 h. In order to examine the kinetics of the process the level of whiteness is determined. The data obtained from the thermal aging of the paper are treated using the laws of polychrome kinetics. [ABSTRACT FROM AUTHOR]

Abstract This work presents a novel method for the sensitive and selective detection of atmospheric hydroxyl radicals (OH). After activation by a hydrothermal method in the presence of sodium citrate, carbon fiber paper (CFP) with good conductivity and hydrophilicity was impregnated with salicylic acid (SA) and used as a detector to monitor OH. The impregnated SA can trap atmospheric OH, producing 2,5-dihydroxybenzoic acid (2,5-DHBA), an electroactive species. The concentration of 2,5-DHBA was quantified using a simple electrochemical method to estimate the number of OH radicals that have participated in the reaction. This method provided a linear correlation for 2,5-DHBA concentrations from 1.0 × 10−13 to 3.0 × 10−10 M with a detection limit of 2.09 × 10−14 M, which corresponds to an OH range from 1.0 × 105 to 3.0 × 108 molecules/cm3 with a detection limit of 2.1 × 104 molecules/cm3. This method has been used to measure the atmospheric OH levels in Yangzhou. Graphical abstract Unlabelled Image Highlights • Carbon fiber paper (CFP) plays two roles in the measurement of atmospheric OH: collection and detection. • C O was introduced to improve the CFP affinity for salicylic acid (SA). • Atmospheric OH was detected by a SA-impregnated CFP via measurement of 2,5-DHBA. • The OH detection limit is 2.1 × 104 molecules/cm3 [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel route to carbon quantum dots (CQDs) of customized surface functionality. • CQDs with amine functionality obtained from modified paper precursors. • Amine functionalized CQDs demonstrated as efficient probes for DNA binding studies. We report a novel synthesis route for preparing carbon quantum dots (CQDs) of customized surface functionality from readily available precursors. The synthetic strategy is based on the chemical modification of paper precursors prior to preparing CQDs from them. The pre-synthesis modification of paper precursors with (3-Aminopropyl) triethoxy silane (APTES) enabled us to synthesize CQDs with amine functional groups on the surface. The silane coupling via condensation between the ethoxy group of APTES and the cellulose hydroxyl group on the paper resulted in the tethering of amine groups on the paper substrates, which are retained as surface-bound species during the synthesis of CQDs from the modified paper. Amine functionalization on the surface of CQDs helped us use them in applications such as DNA binding. We analyzed the interaction of CQDs with calf thymus DNA (CT-DNA), and the results imply their propensity as an efficient biological probe. The synthetic strategy presented here can also be extended to other functional groups. [ABSTRACT FROM AUTHOR]

In this study, we developed a rotatable paper device integrating loop-mediated isothermal amplification (RT-LAMP) and a novel naked-eye readout of the RT-LAMP results using a food additive, carmoisine, for infectious pathogen detection. Hydroxyl radicals created from the reaction between CuSO4 and H2O2 were used to decolor carmoisine, which is originally red. The decolorization of carmoisine can be interrupted in the presence of DNA amplicons produced by the RT-LAMP reaction due to how DNA competitively reacts with the hydroxyl radicals to maintain the red color of the solution. In the absence of the target DNA, carmoisine is decolored, owing to its reaction with hydroxyl radicals; thus, positive and negative samples can be easily differentiated based on the color change of the solution. A rotatable paper device was fabricated to integrate the RT-LAMP reaction with carmoisine-based colorimetric detection. The rotatable paper device was successfully used to detect SARS-CoV-2 and SARS-CoV within 70 min using the naked eye. Enterococcus faecium spiked in milk was detected using the rotatable paper device. The detection limits for the SARS-CoV-2 and SARS-CoV targets were both 103 copies/µL. The rotatable paper device provides a portable and low-cost tool for detecting infectious pathogens in a resource-limited environment. [ABSTRACT FROM AUTHOR]

Flexible and conductive polypyrrole (PPy) paper shows the potential use in electromagnetic shielding, antistatic packaging, and electrochemical materials due to its low cost and facile manufacturing procedure. However, the poor mechanical strength and relatively low electrical stability of PPy paper is still challenging. In this study, we use horseradish peroxidase polymerized sulfonated alkaline lignin (HSAL) as a dispersant and dopant for PPy and demonstrate mechanically strong and electrically stable PPy paper by a combination of multiple impregnations and in-situ polymerization. The abundant sulfonic, carboxyl, and phenolic hydroxyl groups of HSAL could significantly improve the interfacial interaction between cellulose fibers and PPy. Meanwhile, its high molecular weight facilitated the uniform distribution of pyrrole along the fiber axial direction during in-situ polymerization. As a result, the resulting PPy paper exhibits enhanced mechanical properties and electrical stability, as well as high conductivity (24.84 S cm−1). More significantly, we investigated the influences of the dosage of HSAL and the cycles of multilayer impregnations on the electrical and mechanical properties of PPy paper. This work sheds light on the design and fabrication of flexible and conductive PPy paper with superior mechanical robustness and stable electrical performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cocklebur structured fiber design was developed for polypyrrole modified fibers. • Formation of fibrous polypyrrole on the modified-fiber surface with high yield. • An all-in-one paper supercapacitor was produced with the papermaking technology. • Electrodes and separator were integrated by the inter-layer bonding of paper. In the era of miniaturization, low-cost, high mechanical stability and lightweight are the pre-requisites for the commercialization of smart-wearable supercapacitors (SCs). For this purpose, light-weight, binder-free, sustainable cellulose based thin-films with conductive polymers such as polypyrrole (PPy) have attained considerable attention. However, the delamination of the conductive materials in sandwich-type structures of SCs, particularly during the cyclic bending process at high current densities, is a great challenge for wearable SCs. To circumvent the problem of delamination of conductive materials, multi-layer forming concept that consists of three sequential steps (forming, pressing and drying) in papermaking technology has inspired us to prepare mechanically ultra-stable paper electrodes towards for wearable SCs. For this reason, we firstly adopted the multi-layer concept to design all-in-one paper flexible SCs by integrating PPy-modified cellulose fibers as electrodes, and un-modified cellulose paper as a separator. More importantly, a cocklebur like structure of PPy-modified cellulose fiber has been attained by the virtue of the strong inter-molecular hydrogen bonding between free hydroxyl groups on the surface cellulose fibers and PPy, resulting in increased PPy loading, and thus enhancing the electrochemical properties of the all-in-one paper supercapacitor. Furthermore, these hydroxyl groups facilitate the inter-layer bonding of the paper structure in the subsequent pressing and drying processes, favoring the integration of the electrodes and separator. Benefiting from the multi-layer forming concept and suitable morphology of PPy- modified cellulose, we have prepared an ultra-thin (150 μm) all-in-one paper SC with high areal specific capacitance (up to 562 mF cm−2), high energy density (up to 3.1 mWh cm−3) and high-power density (up to 414.9 mW cm−3). Moreover, the all-in-one paper SC shows excellent flexibility, with negligible specific capacitance loss by bending at 0° to 180° angles after repeating 1000 times. The proposed concept and supercapacitor fabrication process is scalable and can be readily implemented in a modern paper industry. [ABSTRACT FROM AUTHOR]

As a typical advanced oxidation process, Fe2+-persulfate (PDS) oxidation technology has been widely and efficiently reported for enhancing sludge dewaterability. However, higher dosage of Fe2+ must be added, which will restrain the oxidation efficiency of Fe2+-PDS process. In this work, the oxalic acid (OA)/Fe2+-PDS process was studied to improve paper sludge dewatering. With the OA dosage of 6 μmol (g total solid (TS))−1, Fe2+ dosage of 0.3 mmol (g TS)−1, and PDS dosage of 0.6 mmol (g TS)−1, sludge dewaterability was improved more efficiently. The specific resistance to filtration and water content of sludge cake were decreased by 70.7% and 8.0%, respectively. In comparison with Fe2+-PDS process, the viscosities of sludge suspension and supernatant were further reduced by 3.73% and 51.77%, respectively, and the contents of extracellular polymeric substances fractions were increased. The improved sludge dewaterability in OA/Fe2+-PDS process was mainly contributed by the synergistic effect of oxidative disintegration by free radicals and flocs re-flocculation, the contributions of which were the orders: metal cations > sulfate radical > hydroxyl radical. OA enhanced the efficient disintegration of sludge flocs, released more bound water, generated more Fe3+-oxalate complexes, and finally increased the sludge particle size significantly, forming a larger aggregation and obvious cracks. Additionally, the stabilization of several heavy metals was improved due to the chelating capacity of OA. These works will provide a novel approach for sludge dewatering in the PDS oxidation process. [Display omitted] • Oxalic acid (OA) chelated Fe2+ activated persulfate process was more efficient for enhancing sludge dewaterability. • Free radicals oxidation and flocculation effect were the proposed pathways on the improvement of sludge dewaterability. • OA promoted the recovery of Fe2+ and the production of Fe3+-oxalate complexes. • The release of water bound on extracellular polymeric substances improved sludge dewaterability. [ABSTRACT FROM AUTHOR]

Abstract: Recent work showed that carbon nanotubes could be fabricated into bucky-paper structures as self-supporting membranes and their hydrophobic property used for water desalination by membrane distillation. Carbon nanotube bucky-papers possess very interesting properties such as natural hydrophobicity, high porosity and very high specific surface area, making of them promising candidates for separation applications. However, to inhibit crack formation associated with poor mechanical stability, improved durability structures that retain a high degree of hydrophobicity need to be developed. In this work we chemically modified high purity carbon nanotubes by (i) UV/ozone treatment to create hydroxyl groups and (ii) reacting those groups by substitution with alkoxysilane based groups. The resulting nanotubes presented a silicon content up to 2.5% and the bucky-papers produced had larger contact angle (140° compared to 125°) and liquid entry pressures. We report here on their fabrication and use as membranes in direct contact membrane distillation. [Copyright &y& Elsevier]

[Display omitted] • A novel multiple cross-linked PVA nanocomposite (MPAU) was constructed. • Incorporation of SiO 2 provides physical cross-linking domains. • PVA, TBPU and BGT generate chemical-coordination domains. • MPAU show excellent mechanical strength (58.9 MPa) and toughness (79.5 MJ/m3). Materials based on fiber-reinforced coating have gained increasing attention due to their environmental and industrial application tracks. Polyvinyl alcohol (PVA) composites with interpenetrating cross-linked structures and abundant functional groups exhibit obvious advantages for high-performance coating. In this work, PVA multiple cross-linked network nanocomposites (MPAUs) were established using silica nanoparticles as reinforcing fillers, ingeniously synthesized boronic esters (BGTs) and blocked-diisocyanate polyurethanes (TBPUs) as cross-linkers. Briefly, SiO 2 nanoparticles were evenly dispersed into PVA matrix to fabricate primary physical cross-linked network, which could promote subsequent cross-linking and esterification effects. After deblocking, TBPU molecules were grafted onto PVA chains via radical polymerization. Meanwhile, the borate ions B(OH) 4 − generated by the multi-stage ionization of BGT were re-coordinated with the hydroxyl groups of PVA matrix. These two effects further afforded secondary chemical cross-linking networks and coordination cross-linked domains. The mechanical and microstructural properties of MPAUs were assessed with respect to their cross-link density and multiple cross-linked network structure. Of note, the formation of multiple-cross-linking network enabled MPAU films with substantial enhancements in mechanical strength and toughness, reaching to 58.9 MPa and 79.5 MJ/m3, respectively. The results of application studies indicated that the obtained MPAUs could integrate with cellulose paper to accomplish excellent physical strength and surface properties. In conclusion, this work paves the way to fabricate multifunctional nanocomposites, which enriches the commercial value of versatile paper-based materials. [ABSTRACT FROM AUTHOR]

The hydroxyl groups on the cellulose macromolecular chain cause the cellulose surface to have strong reactivity. In this study, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PDOTES) was used to modify cellulose to improve its triboelectric properties, and a triboelectric nanogenerator (TENG) was assembled. The introduction of fluorine groups reduced the surface potential of cellulose and turned it into a negative phase, which enhanced the ability to capture electrons. The electrical properties increased by 30% compared with unmodified cellulose. According to the principles of TENGs, a self-powered human-wearable device was designed using PDOTES-paper, which could detect movements of the human body, such as walking and running, and facilitated a practical method for the preparation of efficient wearable sensors. [ABSTRACT FROM AUTHOR]

A facile route for the large scale production of graphene oxide (GO) papers and their mechanical enhancement has been presented in this work. The novel paper-like GO made from individual GO sheets in aqueous suspension can be achieved in large scale by a simple drop casting method on hydrophobic substrates. Significant enhancement in mechanical stiffness (341%) and fracture strength (234%) of GO paper have been achieved upon modification with a small amount (less than 10 wt%) of glutaraldehyde (GA). The cross-linking reaction takes place between hydroxyl groups on the surface of GO and aldehyde groups of GA, through forming hemiacetal structure, which can result in distinct mechanical enhancement of the GO papers. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarization, and a reduction in defects at the interface. [ABSTRACT FROM AUTHOR]

The copper–phenanthroline complex CuI(Phen)2 was the first artificial nuclease studied in biology. The mechanism responsible for this activity involves CuII(Phen)2 and H2O2. Even if H2O2/Cu systems have been extensively studied in biology and oxidative chemistry, most of these studies were carried out at physiological pH only, and little information is available on the generation of radicals by the H2O2/CuII-Phen system. In the context of paper pulp bleaching to improve the bleaching ability of H2O2, this system has been investigated, mostly at alkaline pH, and more recently at near-neutral pH in the case of dyed cellulosic fibers. Hence, this paper aims at studying the production of radicals with the H2O2/CuII-Phen system at near-neutral and alkaline pHs. Using the EPR/spin-trapping method, HO• formation was monitored to understand the mechanisms involved. DMPO was used as a spin-trap to form DMPO–OH in the presence of HO•, and two HO• scavengers were compared to identify the origin of the observed DMPO–OH adduct, as nucleophilic addition of water onto DMPO leads to the same adduct. H2O2 decomposition was enhanced by the addition of CuII–Phen (and only slightly by addition of CuSO4), reaching a level similar to the Fenton reagent at near-neutral pH. This evidences the role of Phen, which improves the effect of CuII by tuning the electronic structure and structural properties of the corresponding CuII complexes. [ABSTRACT FROM AUTHOR]

The structure and properties of ethanol organosolv lignin (EOL) extracted from bamboo under various conditions were characterized. EOL yield increased at high temperatures of 160 to 200 °C and a reaction time of 1 to 3 h. The nitrogen content in lignin was low, with a maximum of 0.62%. The carbon content increased with increasing temperature and prolonged time, whereas oxygen content showed an inverse trend. EOL extracted from bamboo showed high purity levels (more than 95.5% Klason lignin) with low impurity contents (carbohydrate and ash). The severity of the process increased the carboxylic acid and phenolic hydroxyl group contents and also decreased the methoxyl group content. The molecular weight of EOL varied depending on the extraction condition. The FT-IR and NMR spectra revealed that the main structure did not significantly change. From the spectra, it is clear that EOL extracted from bamboo can be classified as an HGS (H--p-hydroxyphenyl, G--guaiacyl, and S-- syringyl, respectively) type. Clear β-O-4, β-β, and β-5' linkages were observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Introduce the end-blocked structure into the water-based functional polyurethane segments applied as a "latent cross-linker" for surface sizing, • A novel compound sizing system containing water-based blocked polyurethane and polyvinyl alcohol, • Chemical bonding and hydrogen bonding between highly active isocyanate groups and paper fiber after unblocking, • Application of water-based blocked polyurethane in surface sizing of special paper. Efficient improvement of paper strength while optimized sizing technique remains challenging and fascinating since specialty paper are required to low-cost, high printing quality and environmental sustainability. Herein, a novel controlled reactivity polyester glycol-based cross-linker (TBPU) applied in paper surface sizing was exploited by simple two-steps polymerization and blending process. An end-blocked structure design strategy of containing densely distributed multiple soft segments and active hydrogen nucleophilic segments (Butanone oxime, MEKO as end closure units) in isocyanate dispersion was achieved to address the scarcity of mechanical properties and the inconvenient in surface-sizing progress. TBPU can block the NCO groups in IPDI segments at 60 °C, and NCO groups can be deblocked at the temperature higher than 110 °C, which endow TBPU with latent cross-linking property. Afterward, we took advantage of the structural feature of polyhydroxy compounds and the adhesion to cellulose via using polyvinyl alcohol (PVA) as a blending component to form TBPU/PVA emulsion. The organization of NCO groups react with hydroxyl groups, carbamate groups cross-linked with hydrogen bonds, and crystallized PCL segments generates phase-separated hierarchical domains. Serving as high-reactivity paper-sizing fillers capable of cross-linking and disintegration under an external change of temperature, the hierarchical domains can strengthen the specialty papers and enhance their water resistance and ink adhesion. The influences of TBPU content, PVA content and NCO/ OH molar ratio on the physicochemical properties of the resultant emulsions and sized paper have been investigated. As a result, the paper sized with TBPU-1.6/PVA emulsion exhibit a tensile index of ≈107.19 Nm/g, a tearing index of ≈11.79 m N • m2/g, a folding resistance of ≈4511 s, an optimum blending temperature of 70 °C and exceptional cooperation ratio with PVA and TBPU (4.0 wt%, 3.0 wt%), which are 1.649 times, 1.966 times, and 2.652 times than those of untreated papers (65 Nm/g, 6 m N • m2/g, 1701 s). Furthermore, sizing liquid can be conveniently applied and recycled due to their excellent environmental friendliness and Biodegradability, this work provides a promising solution for optimizing surface sizing technology. [ABSTRACT FROM AUTHOR]

Development of portable, sensitive and reliable devices for Ochratoxin A (OTA) detection is highly demanded, especially for resource-limited regions. Herein, a novel paper-based analytical device (PAD) is designed through wax printing and screen-printed technologies, which integrates sample flowing, electrode modification, cleaning and electrochemical (EC)/colorimetric signal output. To greatly enhance the detection sensitivity, we synthesized a chitosan functionalized MoS 2 –Au@Pt (Ch-MoS 2 -Au@Pt) via electrostatic self-assembly, and used it to immobilize the label aptamer (apta 2) for signal regulation and amplification. Concretely, with the addition of analytes, the Ch-MoS 2 -Au@Pt-apta 2 could be combined on the sensing interface by specific biorecognition and catalyzed reduction of H 2 O 2 , resulting in a remarkable EC response. Meanwhile, the released hydroxyl radicals (·OH) flowed to the visualization zone and promoted the oxidation of 3,3′,5,5′-tetramethylbenzidine for colorimetric detection. Consequently, the dual-mode PAD achieved acceptable prediction and accurate analysis in the range of 0.1–200 ng mL−1 and 1 × 10−4-200 ng mL−1 by matching the visual and EC signal intensity, respectively. Compared with traditional single-mode sensor for OTA, the proposed dual-mode aptasensor featuring independent signal conversion and readout, not only avoided the false-positive signal associated with detection condition and operation, but also enlarged the detection ranges and improved the sensitivity. Furthermore, the consistency of EC/colorimetric assay was validated in real OTA samples. Overall, this work provided a portable, cost-effective, sensitive and visualized aptasensor platform, which could be extended to various other mycotoxins in the field of food safety. [Display omitted] • A paper-based analytical device (PAD) integrated electrochemical/colorimetric assay was designed for the OTA detection. • Ch-MoS 2 -Au@Pt nanozyme exhibited excellent peroxidase-like catalytic activity as signal amplification strategy. • The dual-mode PAD improved detection range and accuracy, which was superior to that in reported OTA assays. • This work provided a portable, cost-effective, sensitive and visualized general analytical platform for various mycotoxins. [ABSTRACT FROM AUTHOR]

In this study, hexagonal boron nitride nanosheets enriched with hydroxyl groups (h-BN-OH) were successfully grafted on the surface of cellulose fibers after the simple and effective exfoliation and oxidation of bulk h-BN. OH groups of h-BN-OH and the ones presented on the surface of cellulose fibers interacted via hydrogen bonding. Both spectroscopic (FT-IR, XRD) and microscopic (TEM, SEM, and atomic force microscopy (AFM)) methods results proved the successful functionalization of the cellulose fibers with the nanomaterial. Modified cellulose fibers were used to prepare paper sheets samples with different concentrations of the nanomaterial (1 wt %, 2 wt %, and 3 wt %). All the samples were tested for the antibacterial properties via the colony forming unit method and exhibited good performance against both Gram-negative (E. coli) and Gram-positive (S. epidermidis) model bacteria. Additionally, the influence of the volume of working bacterial suspension on the antibacterial efficiency of the obtained materials was examined. The results showed significantly better antibacterial performance when the volume of bacterial suspension was reduced. Mechanical properties of the paper samples with and without nanofiller were also characterized. Tensile strength, tearing strength, and bursting strength of the paper samples containing only 2 wt % of the nanofiller were improved by 60%, 61%, and 118% in comparison to the control paper samples, respectively. Furthermore, the nanofiller improved the thermal properties of the composite paper—the heat release rate decreased by up to 11.6%. Therefore, the composite paper can be further explored in a wide range of antibacterial materials, such as packaging or paper coatings [ABSTRACT FROM AUTHOR]

A more flexible salamo-based sensor DNTS was designed and synthesized, with dual modes of colorimetry and fluorescence turn on to sense CN−. In addition, the introduction of Cu2+ ions will form a more stable complex with CN−, which makes the sensor repeatable. [Display omitted] • A more flexible salamo-based chemical sensor DNTS for dual-channel identification of CN− was synthesized. • The sensor DNTS can be recycled through adding of Cu2+ ions. • The sensor DNTS can be made into a simple test strip for real-time monitoring. A more flexible salamo-based chemical sensor DNTS was designed and synthesized, with dual modes of colorimetry and luminescence turn on to sense CN−. The performance of the sensor DNTS has been studied in detail through UV and fluorescence spectroscopy. Meanwhile, the recognition mechanism has been reasonably proved that the interaction between DNTS and CN− leads to the deprotonation of the hydroxyl group, followed by the π-π stacking process, resulting in luminescence. The sensor DNTS can detect cyanide with high sensitivity through proportional fluorescence (398/468 nm), and its detection limit is about 0.128 μM. In addition, the successful used of the Cu2+ and CN− coordination mechanism making the sensor repeatable. In short, the sensor DNTS will be a promising device for detecting cyanide based on the successful development of test strips. [ABSTRACT FROM AUTHOR]

In this paper, a novel fluorescent detection method for glucose and lactic acid was developed based on fluorescent iron nanoclusters (Fe NCs). The Fe NCs prepared using hemin as the main raw material exhibited excellent water solubility, bright red fluorescence, and super sensitive response to hydrogen peroxide (H2O2). This paper demonstrates that Fe NCs exhibit excellent peroxide-like activity, catalyzing H2O2 to produce hydroxyl radicals (•OH) that can quench the red fluorescence of Fe NCs. In this paper, a new type of glucose sensor was established by combining Fe NCs with glucose oxidase (GluOx). With the increase in glucose content, the fluorescence of Fe NCs decreases correspondingly, and the glucose content can be detected in the scope of 0–200 μmol·L−1 (μM). Similarly, the lactic acid sensor can also be established by combining Fe NCs with lactate oxidase (LacOx). With the increase in lactic acid concentration, the fluorescence of Fe NCs decreases correspondingly, and the lactic acid content can be detected in the range of 0–100 μM. Furthermore, Fe NCs were used in the preparation of gel test strip, which can be used to detect H2O2, glucose and lactic acid successfully by the changes of fluorescent intensity. [ABSTRACT FROM AUTHOR]

Reactive dyes constitute a significant portion of colorants used in industries ranging from the textile industry to the paper industry. In most cases, the effluent streams from textile plants are highly colored, and treatment methods for dye decolorization such as chemical oxidation need to be explored. The oxidation processes investigated in this study are those of ozonation, ultrasound, and ultrasound-enhanced ozonation. The oxidation of an anthraquinone dye was studied under conditions of varying ultrasonic power, dye concentration, ozone concentration, pH, and temperature. Laboratory experiments were performed using a semibatch reactor by ozonating dye samples with and without ultrasound. Under conditions of constant ultrasonic radiation and continuous gas application, decolorization rates have been enhanced by ultrasound. The apparent first-order rate constants increased between 35 and 204% for the ultrasonic power inputs between 40 W/L and 120 W/L compared with ozonation alone. The effects of ultrasonic power input on the gas-liquid mass-transfer coefficient were also investigated and the results indicate that an increase in ultrasonic power input increases the mass-transfer coefficient. The mass-transfer coefficient increased between 89 and 93% for ozone inlet concentrations between 5.4 and 9.4 mg/L at an ultrasonic power of 120 W/L compared with ozonation alone. The reactions of the dye with ultrasound-enhanced ozone occurred through the hydroxyl radical pathway. [ABSTRACT FROM AUTHOR]

To adopt cleaner production technology of photo-catalysis in papermaking industry and improve environmental sustainability, it is essential to understand the impact of ambient humidity on photo-catalytic degradations of gaseous pollutants. This study used TiO 2 colloid as catalyst to study the effects of ambient humidity (30–60%) on the photo-catalytic degradations of formaldehyde (HCHO), benzene (C 6 H 6), and hydrogen sulfide (H 2 S) generated by papermaking industry. Via adsorption behavior simulations, using density functional theory (DFT) and catalytic reaction mechanisms, the effects of humidity were further investigated. The following results were found: (1) With increasing humidity, the degradation of HCHO was inhibited, because the ambient H 2 O content exceeded the demand for hydroxyl radicals produced by H 2 O, which led to competitive adsorption. (2) For C 6 H 6 , an optimum humidity of 40% was identified during the degradation process, which could be attributed to the improved catalytic reaction and the subsequent excessive H 2 O content. (3) For H 2 S, unlike the negative action for HCHO and the first positive and then negative actions for C 6 H 6 , with increasing humidity, the H 2 S degradation was promoted. This indicated that the large demand for hydroxyl radicals produced by H 2 O promoted the H 2 S catalytic reaction. Combining experimental, simulation, and theoretical results for these different gaseous pollutants provides sufficient information to understand the impact of humidity on the photo-catalytic oxidation degradation process. • From adsorption and catalysis, humidity effects on photo-catalysis were studied. • Excessive H 2 O content and competitive adsorption inhibited HCHO degradation. • Improved catalysis and then the excessive H 2 O caused 40% optimum humidity for C 6 H 6. • Large demand for hydroxyl radicals produced by H 2 O promoted H 2 S degradation. • Adsorption simulation and catalytic reaction study were verified with experiments. [ABSTRACT FROM AUTHOR]

Using a photosensitizer (PS), light, and oxygen, photodynamic therapy creates cytotoxic reactive oxygen species, such as singlet oxygen (1O2), that kill cancer cells. Many cancer cell lines have up to 300 times more folic acid receptors than healthy cells. Therefore, folic acid is often used to improve selectivity of PSs. Photobleaching poses a disadvantage for PSs. In this paper, we have studied the photoinduced changes of meso-substituted cationic pyridyl porphyrins in the presence of folic acid using fluorescence and absorption spectroscopy. In this work, it was demonstrated that L-histidine, which is a 1O2 quencher, and D-mannitol, which is a hydroxyl radical quencher, can reduce photobleaching of cationic porphyrins and their interaction products with FA. This implies both singlet oxygen and hydroxyl radicals are involved in photobleaching. Additionally, our study revealed certain important features of the photobleaching of cationic porphyrins in the presence of folic acid. [ABSTRACT FROM AUTHOR]

This paper investigated the effects of steam explosion (SE) pretreatment on the structural characteristics and antioxidant activity of Hypsizygus marmoreus polysaccharides (HPS). Hypsizygus marmoreus samples were pretreated at different SE temperatures (120–200 °C) and polysaccharides were extracted using the water extraction and alcohol precipitation method. The results showed that SE pretreatment improved the extraction rate of HPS. Under the conditions of SE treatment time of 60 s and temperature of 160 °C, the extraction rate of HPS was the highest (8.78 ± 0.24%). After SE pretreatment, the structural changes of HPS tended to enhance the antioxidant activity, which showed that the content of Gal and Man in the monosaccharide composition increased and the molecular weight decreased. When testing antioxidant activity in vitro, the ability of SE-pretreated HPS to scavenge DPPH radicals, hydroxyl radicals, and superoxide anion radicals was better than that of HPS without SE pretreatment. Our findings shed light on SE pretreatment as an efficient method for extracting active polysaccharides, providing a new way to improve their extraction rate and biological activity. [ABSTRACT FROM AUTHOR]

In the atmosphere, carbon monoxide (CO) is the major sink for the hydroxyl radical (OH∙), has multiple anthropogenic and natural sources and considerable spatial and seasonal variability. Measurements of CO isotopic composition are useful in constraining the strengths of its individual source and sink processes and thus its global cycle. A fully automated system for δ13C and δ18O analysis has been developed to extract CO from an air sample, convert CO into carbon dioxide (CO2) using the Schütze reagent, and then determine the isotopic composition in an isotope ratio mass spectrometer (IRMS). The entire system is continuously flushed with high-purity helium (He), the carrier gas. The blank signal of the Schütze reagent is only 1-3% of the typical sample size. The repeatability is 0.1% for δ13C and 0.2 for δ18O. The peak area allows simultaneous determination of the mole fraction with an analytical repeatability of ∼ 0.7 nmolmol-1 for 100mL of typical ambient air (185.4 nmolmol-1 of CO). A single, automated, measurement is performed in 18 min, so multiple measurements can be combined conveniently to improve precision. [ABSTRACT FROM AUTHOR]

The Community Atmosphere Model (CAM), version 5, is now coupled to extensive tropospheric and stratospheric chemistry, called CAM5-chem, and is available in addition to CAM4-chem in the Community Earth System Model (CESM) version 1.2. Both configurations are well suited as tools for atmospheric-chemistry modeling studies in the troposphere and lower stratosphere, whether with internally derived "free running" (FR) meteorology, or "specified dynamics" (SD). The main focus of this paper is to compare the performance of these configurations against observations from surface, aircraft, and satellite, as well as understand the origin of the identified differences. We partic ularly focus on comparing present-day methane lifetime estimates within the different model configurations, which range between 7.8 years in the SD configuration of CAM5- chem and 8.8 years in the FR configuration of CAM4-chem. We find that tropospheric surface area density is an important factor in controlling the burden of the hydroxyl radical (OH), which causes differences in tropical methane lifetime of about half a year between CAM4-chem and CAM5-chem. In addition, different distributions of nitrogen oxides (NOx) produced from lightning production explain about half of the difference between SD and FR model versions in both CAM4-chem and CAM5-chem. Remaining differences in the tropical OH burden are due to enhanced tropical ozone burden in SD configurations compared to the FR versions, which are not only caused by differences in chemical production or loss, but also by transport and mixing. For future studies, we recommend the use of CAM5-chem, due to improved aerosol description and inclusion of aerosol-cloud interactions. However, smaller tropospheric surface area density in the current version of CAM5-chem compared to CAM4-chem results in larger oxidizing capacity in the troposphere and therefore a shorter methane lifetime. [ABSTRACT FROM AUTHOR]

The concept of mimetics can be defined in terms of "learning from others" or "inspired by others", and indeed its essence is "universal". A well-known marvelous example of designing materials inspired by nature is human flight. Essentially, everything can be mimicked somehow in this huge world. In this sense, the characteristics of polysaccharides, including chitosan, can shed light on new product development. Owing to the interesting features of chitosan, such as nontoxicity, biodegradability, antibacterial activity, and the puzzling hydrophobic nature of chitosan films, the synthesis of chitosan-mimetic materials represents a promising strategy for developing a diverse group of functional products. The abundant amino and hydroxyl groups of chitosan are the basis for designing different functional materials. It is expected that chitosanmimetic strategies may potentially address issues or challenges related to the commercial use of chitosan. For example, chitosan functions well as a paper additive (e.g. surface sizing); however, its use is strongly hampered by high cost, poor water-solubility, etc. In this case, chitosan-mimetic products derived from low-cost materials (e.g., starch) may be considered as alternatives to chitosan. Limitless types of products stemming from the interaction between mimetics and chitosan are designable, potentially creating endless opportunities for different industrial sectors. [ABSTRACT FROM AUTHOR]

The hydroxyl radical (OH) plays a key role in the atmosphere, as it initiates most of the oxidation processes of Volatile Organic Compounds (VOCs), and can ultimately lead to the formation of ozone and Secondary Organic Aerosols (SOA). There are still uncertainties associated with the OH budget assessed using current models of atmospheric chemistry and direct measurements of OH sources and sinks have proved to be valuable tools to improve our understanding of the OH chemistry. The total first order loss rate of OH, or total OH reactivity, can be directly measured using three different methods, such as: total OH Loss rate Measurement, Laser Induced Pump and Probe Technique and Comparative Reactivity Method. Observations of total OH reactivity are usually coupled to individual measurements of reactive compounds in the gas phase, which are used to calculate the OH reactivity. Studies using the three methods have highlighted that a significant fraction of OH reactivity is often not explained by individually measured reactive compounds and could be associated to unmeasured or unknown chemical species. Therefore accurate and reproducible measurements of OH reactivity are required. The Comparative Reactivity Method (CRM) has demonstrated to be an advantageous technique with an extensive range of applications, and for this reason it has been adopted by several research groups since its development. However, this method also requires careful corrections to derive ambient OH reactivity. Herein we present an intercomparison exercise of two CRM instruments (CRMLSCE and CRM-MD), conducted during July 2013 at the Mediterranean site of Ersa, Cape Corsica, France. We discuss in detail the experimental approach adopted and how the data sets were processed for both instruments. Corrections required for the two instruments lead to higher values of reactivity in ambient air; overall 20% increase for CRM-MD and 49% for CRM-LSCE compared to the raw data. We show that ambient OH reactivity measured by the two instruments agrees very well (correlation described by a linear least squares fit with a slope of 1 and R2 of 0.75). This study highlights that ambient measurements of OH reactivity with differently configured CRM instruments yield consistent results in a low NOx, terpene rich environment, despite differential corrections relevant to each instrument. Conducting more intercomparison exercises, involving more CRM instruments operated under different ambient and instrumental settings will help in assessing the variability induced due to instrument specific corrections further. [ABSTRACT FROM AUTHOR]

The paper presents the photomechanical effect generated in new azo side-chain polyimides synthesized through a post-functionalization strategy involving the Mitsunobu reaction. Prepared azo polyimide foils were irradiated by a 405 nm diode-laser beam (intensity, I = 100 mW/cm²; polarization, Eǀǀx) for the generation of the photomechanical effect. Despite the low content of azo chromophore (substitution of the hydroxyl group was in the range of 7–35%) and thick cantilevers (thickness ~35 µm), bending angles were in the range of 30–40°. Thermal unbending was not observed for 12 months after turning off the excitation light. Our investigation showed that, despite the low content of azo chromophore, it is possible to achieve photodeformation under polarized light. To the best of our knowledge, this is the first example of the photomechanical response of azo pyridine polymers. [ABSTRACT FROM AUTHOR]

Dairy wastewater (DW) contains a high concentration of organic and inorganic pollutants. In recent years, extensive research has been conducted to develop more efficient techniques for the treatment of DW. Electrochemical advanced oxidation processes (EAOPs) have gained significant attention among the various treatment approaches. EAOPs rely on electrochemical generation of hydroxyl radicals (•OH) which are considered highly potent oxidizing compounds for the degradation of pollutants in DW. In this paper, we provide an overview of the treatment of DW using various EAOPs, including anodic oxidation (AO), electro-Fenton (EF), photo electro-Fenton (PEF), and solar photo electro-Fenton (SPEF) processes, both individually and in combination with other techniques. Additionally, we discuss the reactor design and operating parameters employed in EAOPs. The variation in degradation efficiency is due to different oxidizing agents produced in specific approaches and their pollutant degradation abilities. In AO process, •OH radicals generated on electrode surfaces are influenced by electrode material and current density, while EF procedures use Fe2+ to create oxidizing agents both on electrodes and in the DW solution, with degradation mechanisms being affected by Fe2+, pH, and current density; additionally, PEF and SPEF approaches enhance oxidizing component production and pollutant degradation using ultraviolet (UV) light. Integration of EAOPs with other biological processes can enhance the pollutant removal efficiency of the treatment system. There is a scope of further research to exhibit the effectiveness of EAOPs for DW treatment in large scale implementation. [ABSTRACT FROM AUTHOR]

In this paper, the effects of three postharvest treatments (aerobic, vacuum, vacuum+1-MCP) on browning, active oxygen metabolism and saccharides during storage of deastringent persimmon were researched. Meanwhile, the correlations between browning and other indexes were analyzed. BI of vacuum and vacuum+1-MCP was lower than that in aerobic group, and the browning degree in vacuum+1-MCP group was the lowest. The SOD and APX activities of the three kinds of persimmon treated after harvest decreased and increased respectively, and the SOD activities of the vacuum group were the lowest, the APX activities under vacuum and vacuum+1-MCP conditions were higher than that in aerobic group. At vacuum and vacuum+1-MCP conditions, the increase of CAT activity of persimmon was inhibited, and the accumulation of H2O2 was reduced, with lower ability to inhibit hydroxyl radical and ascorbic acid content. The reducing sugar content of persimmon in vacuum and vacuum+1-McP groups was lower than that in aerobic group, and the increase in vacuum+1-MCP group was the slowest, from 14.10% at the beginning of storage to 14.87% on 12 d. The pectin content of persimmon in vacuum+1-MCP group decreased slowly. Correlation analysis showed that the correlations between browning and various indexes under different postharharvest treatments were different. The persimmon BI was always negatively correlated with pectin, meanwhile positively correlated with reducing sugar. It can be concluded that vacuum and vacuum+1-MCP conditions are more conducive to inhibiting the browning of persimmon after deastringent. [ABSTRACT FROM AUTHOR]

In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the dimer was considered. Ab initio calculations based on the density functional theory were used. The electron parameters of the structures obtained were also analysed. Visualisation of the orbitals of selected structures and their interpretations are presented. The presented research allowed a closer look at the mechanisms of processes that are very common in the automotive and chemical industries. Based on theoretical modelling, it was possible to propose the most efficient catalyst that could find potential application in industry–this is the FAU catalyst with a Cu-O-Fe bimetallic dimer with a hydrated copper centre. The essential result of our research is the improvement in the energetics of the reaction mechanism by the presence of an OH group, which will influence the way NO and NH3 molecules react with each other in the deNOx process depending on the industrial conditions of the process. Our theoretical results suggest also how to proceed with the dosage of NO and N2O during the industrial process to increase the desired reaction effect. [ABSTRACT FROM AUTHOR]

Concentration plays an essential role in generating hydroxyl radicals in irradiated nanoenhancer suspensions. In this paper, we used coumarin-3-carboxylic acid as a hydroxyl radical-specific probe to investigate the hydroxyl radical production of different concentration nanodiamonds (NDs) and CeO2 NPs in phosphate-buffered saline under x-ray irradiation. NDs significantly enhanced hydroxyl radical production, and the maximum enhancement of hydroxyl radical production was observed at a concentration of 10 µg/ml, with an enhanced factor of 1.398 ± 0.262. CeO2 NPs can increase and scavenge hydroxyl radicals at different concentration ranges, with the lowest and highest enhanced factors of 0.623 ± 0.069 and 1.738 ± 0.264, respectively. We tested the hydrodynamic diameter at various concentrations to explore the concentration effect further. We found that with increasing concentration, there might be factors, such as hydroxyl radical recombination and nanoparticle agglomeration, that lead to changes in the enhancement factor. Based on the data from previous and present studies, the experimental results indicate that the concentration factor is essential for hydroxyl radical generation in nanoenhancer suspensions under ionizing radiation. We also provide possible mechanisms for enhancing hydroxyl radical production by nanoenhancers in water under ionizing radiation and the decrease in enhancement factor at high concentrations of nanoenhancers. [ABSTRACT FROM AUTHOR]

Epigallocatechin gallate (EGCG), the key constituent of tea polyphenols, presents challenges in terms of its lipid solubility, stability, and bioavailability because of its polyhydroxy structure. Consequently, structural modifications are imperative to enhance its efficacy. This paper comprehensively reviews the esterification techniques applied to EGCG over the past two decades and their impacts on bioactivities. Both chemical and enzymatic esterification methods involve catalysts, solvents, and hydrophobic groups as critical factors. Although the chemical method is cost-efficient, it poses challenges in purification; on the other hand, the enzymatic approach offers improved selectivity and simplified purification processes. The biological functions of EGCG are inevitably influenced by the structural changes incurred through esterification. The antioxidant capacity of EGCG derivatives can be compromised under certain conditions by reducing hydroxyl groups, while enhancing lipid solubility and stability can strengthen their antiviral, antibacterial, and anticancer properties. Additionally, esterification broadens the utility of EGCG in food applications. This review provides critical insights into developing cost-effective and environmentally sustainable selective esterification methods, as well as emphasizes the elucidation of the bioactive mechanisms of EGCG derivatives to facilitate their widespread adoption in food processing, healthcare products, and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Micro–nanobubbles (MNBs) can generate ·OH in situ, which provides a new idea for the safe and efficient removal of pollutants in water supply systems. However, due to the difficulty in obtaining stable MNBs, the generation efficiency of ·OH is low, and the removal efficiency of pollutants cannot be guaranteed. This paper reviews the application research of MNB technology in water security from three aspects: the generation process of MNBs in water, the generation rule of ·OH during MNB collapse, and the control mechanisms of MNBs on pollutants and biofilms. We found that MNB generation methods are divided into chemical and mechanical (about 10 kinds) categories, and the instability of the bubble size restricts the application of MNB technology. The generation of ·OH by MNBs is affected by the pH, gas source, bubble size, temperature, and external stimulation. And the pH and external stimulus have more influence on ·OH generation in situ than the other factors. Adjusting the pH to alkaline or acidic conditions and selecting ozone or oxygen as the gas source can promote ·OH generation. MNB collapse also releases a large amount of energy, during which the temperature and pressure can reach 3000 K and 5 Gpa, respectively, making it efficient to remove ≈90% of pollutants (i.e., trichloroethylene, benzene, and chlorobenzene). The biofilm can also be removed by physical, chemical, and thermal effects. MNB technology also has great application potential in drinking water, which can be applied to improve water quality, optimize household water purifiers, and enhance the taste of bottled water. Under the premise of safety, after letting people of different ages taste water samples, we found that compared with ordinary drinking water, 85.7% of people think MNB water is softer, and 73.3% of people think MNB water is sweeter. This further proves that MNB water has a great prospect in drinking water applications. This review provides innovative theoretical support for solving the problem of drinking water safety. [ABSTRACT FROM AUTHOR]

Numerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the Comparative Reactivity Method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel separate VOC emission rates were monitored by a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), and total ozone (O3) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56-69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11-16%. At this time, a large missing fraction of the total OH reactivity emission rate (70-84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes. Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could explain total OH reactivity emissions, during heat stress they could not. The temperature driven algorithm matched the diel course much better in spring than in summer, indicating a different production and emission scheme for summer and early autumn. During these times, unmeasured and possibly unknown primary biogenic emissions contributed significantly to the observed total OH reactivity flux. [ABSTRACT FROM AUTHOR]

Molecular hydrogen (H2) plays an important role in atmospheric chemistry by competing for reactions with the hydroxyl radical (·OH) and contributing to the production of H2O in the stratosphere, indirectly influencing stratospheric ozone concentrations. The dominant pathway for loss of H2 from the atmosphere is via microbially-mediated soil uptake although the magnitude of this loss is still regarded as highly uncertain. Recent studies have shown that abiotic processes such as photochemically mediated degradation (photodegradation) of organic material result in direct emissions of carbon (C) and nitrogen (N)-based trace gases as well as H2. This H2 production has important implications on source-sink dynamics of H2 at the soil-atmosphere interface and thus it is important to quantify its variability over a range of plant types and materials. Here, we show quantitative observations of H2 production and its temperature dependence during abiotic degradation of four plant litter types as well as pure cellulose and high lignin content woody material. A greater amount of H2 was produced in the absence of solar radiation than from photodegradation alone, verifying that low temperature thermal degradation of plant litter is a source of H2. In addition, we measured a significant release of H2 in the absence of O2 in addition to H2 release in the presence of O2. Our results suggest that abiotic release of H2 during organic matter is ubiquitous in terrestrial ecosystems. We propose that because these processes occur at the soilatmosphere interface, they provide a previously unaccounted for proximal source of H2 for microbial uptake and confound interpretation of direct measurements of atmospheric uptake that are important for constraining the global H2 budget. [ABSTRACT FROM AUTHOR]

The article discusses a study which compares hydroxyl radical (OH) concentration measurements using differential optical absorption spectroscopy (DOAS) and laser-induced fluorescence (LIF) during SAPHIR chamber experiments. It explores the potential for artifacts in LIF measurements for the specific conditions of high OH reactivity and low NO concentration. Observed differences between LIF and DOAS measurements are provided.

A variety of tools are used to simulate atmospheric aging, including smog chambers and flow reactors. Traditional, large-scale smog chambers age emissions over the course of hours to days, whereas flow reactors rapidly age emissions using high ox- idant concentrations to reach higher degrees of oxygenation than typically attained in smog chamber experiments. The atmospheric relevance of the products generated under such rapid oxidation warrants further study. However, no previously published studies have compared the yields and chemical composition of products generated in flow reactors and smog chambers from the same starting mixture. The yields and composition of the organic aerosol formed from the photo-oxidation of α-pinene and of wood combustion emissions were determined using aerosol mass spectrometry in a smog chamber (SC) and two flow reactors: a potential aerosol mass reactor (PAM) and a micro-smog chamber (MSC). Reactants were sampled from the SC and aged in the MSC and PAM using a range of hydroxyl radical (OH) concentra15 tions and then photo-chemically aged in the SC. The maximum yields/emission factors and the chemical composition of the products in both the α-pinene and wood combustion systems determined with the PAM and SC agreed reasonably well. High OH exposures have been shown previously to lower yields by breaking carbon-carbon bonds and forming higher volatility species, which reside largely in the gas phase, however, fragmentation in the PAM was not observed. The yields determined using the PAM for the α-pinene system were slightly lower than in the SC, possibly from increased wall losses of gas-phase species due to the higher surface area to volume ratios in the PAM, even when offset with better isolation of the sampled flow from the walls. The α-pinene SOA results for the MSC were not directly comparable, as particles were smaller than the optimal AMS transmission range. For the wood combustion system, emission factors measured by the MSC were typically lower than those from the SC, possibly due to nucleation mode particles not observed by the AMS or the condensational loss of gases to the walls inside or after the MSC. The chemical composition of products in the flow reactors and SC were in reasonable agreement in both systems. The emission factors determined using the flow reactors increased relative to the SC when the wood combustion emissions contained higher fractions of aromatic compounds, suggesting that the performance of the flow reactors may be dependent on the chemical composition of the reactants. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the effects of the lanthanide ions Ce3+, Pr3+, Nd3+ and Sm3+ on the electronic structure and antioxidant and biological (antimicrobial and cytotoxic) properties of p-coumaric acid (p-CAH2). Structural studies were conducted via spectroscopic methods (FTIR, ATR, UV). Thermal degradation studies of the complexes were performed. The results are presented in the form of TG, DTG and DSC curves. Antioxidant properties were determined via activity tests against DPPH, ABTS and OH radicals. The reducing ability was tested via CUPRAC assays. Minimum inhibitory concentrations (MICs) of the ligand and lanthanide complexes were determined on E. coli, B. subtilis and C. albicans microorganisms. The antimicrobial activity was also determined using the MTT assay. The results were presented as the relative cell viability of C. albicans, P. aeruginosa, E. coli and S. aureus compared to controls and expressed as percentages. In the obtained complexes in the solid phase, lanthanide ions coordinate three ligands in a bidentate chelating coordination mode through the carboxyl group of the acid. Spectroscopic analysis showed that lanthanide ions increase the aromaticity of the pi electron system of the ligand. Thermal analysis showed that the complexes are hydrated and have a higher thermal stability than the ligand. The products of thermal decomposition of the complexes are lanthanide oxides. In the aqueous phase, the metal combines with the ligand in a 1:1 molar ratio. Antioxidant activity tests showed that the complexes have a similar ability to remove free radicals. ABTS and DPPH tests showed that the complexes have twice the ability to neutralise radicals than the ligand, and a much higher ability to remove the hydroxyl radical. The abilities of the complexes and the free ligand to reduce Cu2+ ions in the CUPRAC test are at a similar level. Lanthanide complexes of p-coumaric acid are characterised by a higher antimicrobial capacity than the free ligand against Escherichia coli bacteria, Bacillus subtilis and Candida albicans fungi. [ABSTRACT FROM AUTHOR]

The natural product Desmosdumotin D (hereafter referred to as Des-D), isolated from the plant Desmos dumosus, showed potent anti-HIV activity. However, the subsequent pharmacological activity and clinical studies are limited due to the low content of Des-D in the plant. Therefore, the total synthesis path of Des-D was optimized in this paper, and the total yield was increased from 4.4% to 11.9%. Additionally, twelve analogues were obtained following the synthesis route of Des-D. The anti-HIV activity evaluation results in vitro showed that Des-D had the highest activity, with an IC50 value of 13.6 μM, and compounds 17 and 11 had the lowest anti-HIV activity, with IC50 values of 101.3 μM and 161.0 μM, respectively. Through the molecular docking of compounds Des-D and 17 with HIV-IN, the results show that phenolic hydroxyl groups and two benzene rings interact with HIV-IN and are possible pharmacodynamic groups. [ABSTRACT FROM AUTHOR]

Nowadays, antibiotics are widely used, increasing the risk of contamination of the water body and further threatening human health. The traditional water treatment process is less efficient in degrading antibiotics, and the advanced oxidation process (AOPs) is cleaner and more efficient than the traditional biochemical degradation process. The combined ozone/peroxymonosulfate (PMS) advanced oxidation process (O3/PMS) based on sulfate radical (SO4•−) and hydroxyl radical (•OH) has developed rapidly in recent years. The O3/PMS process has become one of the most effective ways to treat antibiotic wastewater. The reaction mechanism of O3/PMS was reviewed in this paper, and the research and application progress of the O3/PMS process in the degradation of antibiotics in drinking water and wastewater effluent were evaluated. The operation characteristics and current application range of the process were summarized, which has a certain reference value for further research on O3/PMS process. [ABSTRACT FROM AUTHOR]

Based on the reported research, hydroxyl radicals can be rapidly transformed into carbonate radicals in the carbonate–bicarbonate buffering system in vivo. Many of the processes considered to be initiated by hydroxyl radicals may be caused by carbonate radicals, which indicates that lipid peroxidation initiated by hydroxyl radicals can also be caused by carbonate radicals. To date, theoretical research on reactions of hydrogen abstraction from and radical addition to polyunsaturated fatty acids (PUFAs) of carbonate radicals has not been carried out systematically. This paper employs (3Z,6Z)-nona-3,6-diene (NDE) as a model for polyunsaturated fatty acids (PUFAs). Density functional theory (DFT) with the CAM-B3LYP method at the 6-311+g(d,p) level was used to calculate the differences in reactivity of carbonate radicals abstracting hydrogen from different positions of NDE and their addition to the double bonds of NDE under lipid solvent conditions with a dielectric constant of 4.0 (CPCM model). Grimme's empirical dispersion correction was taken into account through the D3 scheme. The energy barrier, reaction rate constants, internal energy, enthalpy and Gibbs free energy changes in these reactions were calculated With zero-point vibrational energy (ZPVE) corrections. The results indicated that carbonate radicals initiate lipid peroxidation primarily through hydrogen abstraction from diallyl carbon atoms. The reaction of hydrogen abstraction from diallyl carbon atoms exhibits the highest reaction rate, with a reaction rate constant approximately 43-fold greater than the second-ranked hydrogen abstraction from allyl carbon atoms. This process has the lowest energy barrier, internal energy, enthalpy, and Gibbs free energy changes, indicating that it is also the most spontaneous process. [ABSTRACT FROM AUTHOR]

Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The focus of the study is to elucidate the direct photolysis mechanism of FLO in the water environment and the indirect photolysis of free radicals (·OH, ·NO3, and ·SO4−) as active species. The effect of metal ions Ca2+/Mg2+/Zn2+ on the indirect photolysis was also investigated. The results show that the direct photolysis of FLO involves C–C/C–N/C–S bond cleavage, the C5–S7 bond cleavage is most likely to occur, and the C17–C18 cleavage reaction is not easy to occur during the direct photodegradation of FLO. The indirect photolysis of FLO is more likely to occur in the environment than direct photolysis. The main indirect photolysis involves OH-addition, NO3-addition, and SO4-addition on benzene ring. The order of difficulty in the indirect photolysis with ·OH is C2 > C3 > C4 > C5 > C6 > C1, Ca2+ can promote the indirect photolysis with ·OH, and Mg2+/Zn2+ has a dual effect on the indirect photolysis with ·OH. In other words, Mg2+ and Zn2+ can inhibit or promote the indirect photolysis with ·OH. These studies provide important information for theoretical research on the environmental behavior and degradation mechanism of drug molecules. [ABSTRACT FROM AUTHOR]

Macroscale rolling/sliding conditions are in the superlubricity, a little-studied topic so far. The purpose of this paper is to examine the formation of elastohydrodynamic lubrication (EHL) films by water-based lubricants (glycerol and polyethylene glycol (PEG)), providing superlubricous friction. Experiments were carried out on an optical ball-on-disc tribometer under rolling/sliding conditions. The film thickness was measured by the thin film colorimetric interferometry, and the viscosity of liquids was measured by rotational and high-pressure falling body viscometers. The results show that tribochemical reactions are not the mandatory reason for friction to reach the superlubricity level when using the water-based lubricants. The studied liquids themselves are almost Newtonian. With the addition of water, the signs of shear thinning behavior disappear even more. Suitable conditions for this type of lubricant can be predicted using the known Hamrock–Dowson equations. An anomaly in the thickness of the lubricants was observed as an abrupt change at certain conditions. The more PEG there is in the lubricant, the higher the thickness at the beginning of the jump. [ABSTRACT FROM AUTHOR]