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Exploitation of metal–organic aerogels (MOAs) with porous properties for the immobilization of enzymes should have significant applications. A facile method for the synthesis of MOAs using poly-(propylene glycol) (PPG) as a gelling agent is presented in this paper. In particular, a porous UiO-66-NH2 aerogel containing an iron porphyrin unit has been synthesized using PPG. The MOA not only displays high mesopores for glucose oxidase (GOx) immobilization but also has the unit of iron porphyrin as a peroxidase mimick for a cascade reaction. After the immobilization of GOx, the composite was used for the colorimetric sensing of glucose, exhibiting a good linear range, a low limit of detection, and excellent selectivity. Furthermore, the MOA-immobilized GOx shows enhanced stability against organic solutions and longer storage stability at room temperature, attributed to the protective effect of the UiO-66-NH2 aerogel. This MOA with porous properties should provide an extended platform for enzyme immobilization and open up a route for the development of biocatalyst systems for advanced applications in biosensing, bioindustrial catalysis, and biofuel cells. [ABSTRACT FROM AUTHOR]

This study presents a novel techniquefor the controllable preparationof calcium benzene sulfonate [Ca(Ar–SO3)2] detergents using a microdispersion process. Neutralization andcarbonation were conducted in an oil-in-water system instead of thetypical water-in-oil system. n-Butanol was employedas the oil phase for the in situ formation of the hydrophobic coresof the detergents. The mechanism of synthesis in different bulk phaseswas investigated. Microreactors were used to enhance the mixing performanceand mass transfer. Low-cost Ca(OH)2and dodecyl benzenesulfonic acid (Ar–SO3H) were supplied as the reactants.An efficient synthesis with a high utilization ratio of CO2and a high product yield was achieved. CaCO3nanoparticleswith average sizes from 8 to 20 nm were used as detergent cores, andCa(Ar–SO3)2detergents with total basenumbers (TBNs) ranging from 300 to 420 mg of KOH/g were successfullyprepared. [ABSTRACT FROM AUTHOR]

New gemini surfactant, glycol bis-N-tetradecylnicotinate dibromide (designated EG), and the correspondingmonomer, methyl N-tetradecyl nicotinate bromide (ES), were synthesized and utilized to modify sodium bentonite(Na-Bt). EG-Bt and ES-Bt, the surfactant modifiedbentonites, were then used for methyl orange (MO) removal from thedye solution. EGwas more effective than ESatexpanding the interlayer space of Na-Bt. The adsorption of EG, ESand MO obeyed well the pseudo-second-order kineticmodel and Langmuir isotherms on Na-Bt or on the modified bentonite.However, the adsorption of EGwas more spontaneous thanthat of ES, and EGreplaced more small particles,such as Na+and water, than ESdid during theadsorption on Na-Bt. The elevated temperature impairs the adsorptionof the surfactants, but enhances that of MO. MO absorbed more easilyon EG-Bt than on ES-Bt. When the dosage of thesurfactants used goes beyond a certain amount, the uptake of MO byEG-Bt/ES-Bt decreases slowly owing to desorptionof the surfactants. EGand ESformed a complexwith MO on the modified bentonite as evidenced by UV–vis spectra,and EGexhibited the stronger interaction with MO. [ABSTRACT FROM AUTHOR]

Highlydispersed ZnO nanoparticles were prepared by membrane dispersion usingZnSO4and NH4HCO3aqueous solutionsas raw materials. The particle size and aggregation of ZnO were reducedby intensifying the mixing performance and using CO2bubbles.The properties of the ZnO nanoparticles were characterized by X-raydiffraction, transmission electron microscopy, and Brunauer–Emmett–Telleranalysis. The relationship between the mixing performance of the microreactorand the size and monodispersion of ZnO nanoparticles was investigated.The particle size decreased with the decrease in segregation index Xs. Monodispersion appeared to be related tothe micromixing performance and the ratio Rof dispersedfeed flow rate to continuous feed flow rate. ZnO nanoparticles withsize of 11 nm and agglomeration coefficient CFof 1.181 were successfully prepared when R= 2.0 and Xs= 0.0004. Smaller-sizedZnO nanoparticles showed greater photocatalytic activity toward methylorange with a degradation of 97.5% under UV light radiation for 90min. [ABSTRACT FROM AUTHOR]

Mesoporous ZnO microspheres with a diameter of about 10 μm were prepared through the combination of a membrane-dispersion microstructured reactor with a hydrothermal process. First, ZnSO4reacted with NH4HCO3in a membrane-dispersion reactor to produce the Zn5(CO3)2(OH)6precursor, and then the precursor was treated at the temperature of 80 °C for 2 h to form the Zn5(CO3)2(OH)6microspheres aided by the surfactant CTAB or F127; after the calcinations, mesoporous ZnO microspheres were obtained. The experimental results showed that the morphology of ZnO microspheres obtained using the membrane-dispersion microstructured reactor to mix the raw materials was better than that of those obtained using stirred tanks. Without surfactants and the hydrothermal treatment of the precursors, uniform ZnO microspheres could not be obtained. The SEM images showed that the monodispersed ZnO microspheres were assembled by the plates, and deeper observations revealed that these plates were aggregated by the ZnO nanorods formed by ZnO nanoparticles with a diameter of 9.0 nm. The adsorption–desorption isotherm curve indicated that the ZnO microspheres had mesoporous structures with an average pore diameter of 13.8 nm when using CTAB as the surfactant, and the specific surface area of the ZnO microspheres could reach 71.3 m2/g, much higher than that of ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

Hydroxyl radicals ( • OH) play a significant role in contaminant transformation and element cycling during redox fluctuations in paddy soil. However, these important processes might be affected by widely used agricultural amendments, such as urea, pig manure, and biochar, which have rarely been explored, especially regarding their impact on soil aggregates and associated biogeochemical processes. Herein, based on five years of fertilization experiments in the field, we found that agricultural amendments, especially coapplication of fertilizers and biochar, significantly increased soil organic carbon contents and the abundances of iron (Fe)-reducing bacteria. They also substantially altered the fraction of soil aggregates, which consequently enhanced the electron-donating capacity and the formation of active Fe(II) species (i.e., 0.5 M HCl-Fe(II)) in soil aggregates (0-2 mm), especially in small aggregates (0-3 μm). The highest contents of active Fe(II) species in small aggregates were mainly responsible for the highest • OH production (increased by 1.7-2.4-fold) and naphthalene attenuation in paddy soil with coapplication of fertilizers and biochar. Overall, this study offers new insights into the effects of agricultural amendments on regulating • OH formation in paddy soil and proposes feasible strategies for soil remediation in agricultural fields, especially in soils with frequent occurrences of redox fluctuations.

Research into kappa opioid receptor (KOR) agonists with attenuated central-nervous-system side effects is a critical focus for developing productive and safe analgesics. Herein, a series of ortho -substituted N -cyclopropylmethyl-7α-phenyl-6,14- endo ethano-tetrahydronorthebaines were designed, synthesized, and subjected to bioassays. Compound 7a exhibited high subtype selectivity and potent agonistic activity toward KOR (KOR, K i = 3.9 nM, MOR/KOR = 270, DOR/KOR = 1075; [ 35 S]GTPγS binding, EC 50 = 3.4 nM). Additionally, this compound exhibited robust and persistent antinociceptive effects in rodent models with different animal strains (hot plate test, ED 50 = 0.20-0.30 mg/kg, i.p.; abdominal constriction test, ED 50 = 0.20-0.60 mg/kg, i.p.), with its KOR-mediated mechanism for antinociception firmly established. Notably, compound 7a , unlike conventional KOR agonists, displayed minimal sedation and aversion at the antinociceptive ED 50 dose. This feature addresses a crucial limitation in existing KOR agonists, positioning compound 7a as a promising novel therapeutic agent.

Artificial photoenzymatic systems based on covalent organic frameworks (COFs) provide an interesting platform for converting CO 2 to value-added fuels. However, the dual roles of COFs as photocatalysts and enzyme hosts showcase contradictory preferences for structures, which poses a great challenge for their rational design. Herein, we report the collaborative matching of linkages and linkers in COFs on their ability to exert both photocatalytic activity and enzyme loading, which has been neglected until now. The linkage-dependent linker regulation pattern was elucidated, and the optimal match showed a record-breaking apparent quantum efficiency at 420 nm for photocatalytic cofactor regeneration of 13.95% with a high turnover frequency of 5.3 mmol g -1 h -1 , outperforming other reported crystalline framework photocatalysts. Moreover, theoretical calculations and experiments revealed the mechanism underlying the effects of matching the linkage and linker on exciton dissociation and charge migration in photocatalysis. This newfound understanding enabled the construction of COFs with both high photoactivity and large pores closer in size to the formate dehydrogenase, achieving high loading capacity and a suitable confinement effect. Remarkably, the artificial photoenzymatic system constructed according to optimal linkage-linker matching exhibited highly efficient CO 2 reduction, yielding formic acid with a specific activity as high as 1.46 mmol g -1 catalyst h -1 and good reusability, paving the way for sustainable CO 2 conversion driven by visible light.

The photochemical properties of paddy water might be affected by the commonly used amendments in rice fields owing to the associated changes in water chemistry; however, this important aspect has rarely been explored. We examined the effects of agricultural amendments on the photochemistry of paddy water during rice growth. The amendments significantly influenced the photogenerated reactive intermediates (RIs) in paddy water, such as triplet dissolved organic matter ( 3 DOM*), singlet oxygen, and hydroxyl radicals. Compared with control experiments without amendments, the application of straw and lime increased the RI concentrations by up to 16.8 and 11.1 times, respectively, while biochar addition had limited effects on RI generation from paddy water in in situ experiments under sunlight. Fluorescence emission-excitation matrix spectroscopy, Fourier transform ion cyclotron resonance mass spectrometry, and structural equation modeling revealed that upon the addition of straw and lime amendments, humified DOM substances contained lignins, proteins, and fulvic acids, which could produce more RIs under irradiation. Moreover, the amendments significantly accelerated the degradation rate of 2,4-dichlorophenol but led to the 3 DOM*-mediated formation of more toxic and stable dimeric products. This study provides new insights into the effects of amendments on the photochemistry of paddy water and the pathways of abiotic degradation of organic contaminants in paddy fields.

Nanoparticulate mercury (Hg-NPs) are ubiquitous in nature. However, the lack of data on their concentration in soils impedes reliable risk assessments. This is due to the analytical difficulties resulting from low ambient Hg concentrations and background interferences of heterogeneous soil components. Here, coupled to single particle inductively coupled plasma-mass spectrometry (spICP-MS), a standardized protocol was developed for extraction and quantification of Hg-NPs in natural soils with a wide range of properties. High particle number-, particle mass-, and total mass-based recoveries were obtained for spiked HgS-NPs (74-120%). Indigenous Hg-NPs across soils were within 10 7 -10 11 NPs g -1 , corresponding to 3-40% of total Hg on a mass basis. Metacinnabar was the primary Hg species in extracted samples from the Wanshan mercury mining site, as characterized by X-ray absorption spectroscopy and transmission electron microscopy. In agreement with the spICP-MS analysis, electron microscopy revealed comparable size distribution for nanoparticles larger than 27 nm. These indigenous Hg-NPs contributed to 5-65% of the measured methylmercury in soils. This work paves the way for experimental determinations of indigenous Hg-NPs in natural soils, which is critical to understand the biogeochemical cycling of mercury and thereby the methylation processes governing the public exposure to methylmercury.

Nitrous acid (HONO) is an important photochemical precursor to hydroxyl radicals particularly in an urban atmosphere, yet its primary emission and secondary production are often poorly constrained. Here, we measured HONO and nitrogen oxides (NO x ) at both the inlet and the outlet in a busy urban tunnel (>30 000 vehicles per day) in south China. Multiple linear regression revealed that 73.9% of the inlet-outlet incremental HONO concentration was explained by NO 2 surface conversion, while the rest was directly emitted from vehicles with an average HONO/NO x ratio of 1.31 ± 0.87%, which was higher than that from previous tunnel studies. The uptake coefficient of NO 2 , γ(NO 2 ), on the tunnel surfaces was calculated to be (7.01 ± 0.02) × 10 -5 , much higher than that widely used in models. As tunnel surfaces are typical of urban surfaces in the wall and road materials, the dominance of HONO from surface reactions in the poorly lit urban tunnel demonstrated the importance of NO 2 conversion on urban surfaces, instead of NO 2 conversion on the aerosol surface, for both daytime and night-time HONO even in polluted ambient air. The higher γ(NO 2 ) on urban surfaces and the elevated HONO/NO x ratio from this study can help explain the missing HONO sources in urban areas.

Microbial-mediated transformation of anthropogenic Cd 2+ controls its distribution, bioavailability, and potential risks. However, the processes readily form CdS nanoparticles (CdS-NPs), which exhibit dissolution behavior different from that of larger sized particles. Here, we investigated the effects of morphologies and facets of CdS-NPs on their photoinduced dissolution. Three CdS-NPs, CdS-sphere, CdS-rod, and CdS-sheet, and one nanosized biogenic CdS (Bio-CdS) were synthesized with different dominant facets of {101}, {100}, {001}, and {111} and thus distinct surface chemistry. As explored by HRTEM, EPR, and DFT calculations, photogenerated e - /h + pairs were more likely to generate on CdS-sheet surfaces due to higher surface energies and a narrower band gap, facilitating the formation of •OH and thereby faster dissolution ( k obs = 6.126-6.261 × 10 -2 h -1 ). The wider band gaps of CdS-sphere and CdS-rod caused less formation of O 2 •- and •OH, leading to slower oxidative dissolutions ( k obs = 0.090-0.123 and 2.174-3.038 × 10 -2 h -1 , respectively). Given the similar surface energy as that of CdS-sheet, the dissolution rate of Bio-CdS was close to that of CdS-rod and CdS-sheet, which was 1.6-3.5 times faster than that of larger sized CdS, posing higher environmental risks than thought. Altogether, this work revealed the facet effects on the dissolution of CdS-NPs, manifesting a deeper understanding of metal sulfides' environmental behaviors.

The search for selective kappa opioid receptor (κOR) agonists with an improved safety profile is an area of interest in opioid research. In this work, a series of m -substituted analogs were designed, synthesized, and assayed, resulting in the identification of compound 6c ( SLL-1206 ) as a κOR agonist with single-digit nanomolar activities. The subtype selectivity of compound 6c appeared to be a consequence of an enormous decrease in the affinity for μOR and δOR, rather than a significant increase in the affinity for κOR, which was not the case for SLL-039 , another selective and potent κOR agonist identified in our previous work. Besides reduced central nervous system effects, SLL-1206 exhibited substantially improved physicochemical and pharmacokinetic properties compared with SLL-039 , with increases of over 20-fold in aqueous solubility and approximately 40-fold in oral bioavailability in rats.

Management of moderate to severe pain relies heavily on opioid analgesics such as morphine, oxycodone, and fentanyl in clinics. However, their prolonged use was associated with undesirable side effects. Many new strategies to reduce side effects have been proposed, but not without disadvantages. Using a hot plate model as a phenotypic screening method, our studies identified (3 R ,4 S )- 9d with a new scaffold as a potent analgesic with ED 50 values of 0.54 mg/kg and 0.021 mg/kg in hot plate and antiwrithing models, respectively. Mechanistic studies showed that it elicited its analgesic effect via the active metabolite (3 R ,4 S )- 10 a . The mechanism of (3 R ,4 S )- 10 a -induced activation of the μ opioid receptor (MOR) was proposed by means of molecular dynamics (MD) simulation.

κ opioid receptor (κOR) is a subtype of opioid receptors, and there are two major κOR agonists currently available, morphinans and arylacetamides, which are structurally distinct from each other. Numerous efforts had been made to correlate these series of compounds in order to establish a consensus binding pattern for κOR agonists. Unfortunately, no morphinan-based agent with an arylacetamidyl substituent has been identified as a κOR agonist with a pharmacological profile similar to arylacetamides. Since the recently described morphinan-based compound SLL-039 was identified as a selective and potent κOR agonist that contains a unique benzamidyl substituent in structure similar to arylacetamides, numerous arylacetamidyl substituents were introduced to this scaffold to examine whether the structure-activity relationships (SARs) of arylacetamides in conferring κOR agonistic activities could be reproduced by these analogues. Thus, a series of N -cyclopropylmethyl-7α-arylacetamidylphenyl-6,14-endoethanotetrahydronorthebaine analogues were designed, synthesized, and assayed for biological activities. Among these compounds, compound 4j with a 3',4'-dimethylphenylacetamidyl substituent showed a single digit low nanomolar affinity to the κOR and relatively high subtype selectivity in binding assays, but this profile was not reproduced in functional assays. In contrast, compound 4i displayed moderately selective κOR agonistic activities in functional assays, which was inconsistent with its nonselective nature in binding assays. Overall, introduction of an arylacetamidyl substituent to the morphinan-based scaffold was associated with pharmacological diversity in both binding and functional activities on opioid receptors in vitro . The resultant SARs were inconsistent with that of classical arylacetamides as κOR agonists, despite bearing a similar arylacetamidyl substituent in the structure. Therefore, the arylacetamidyl substituent of the morphinan-based scaffold was found to be disconnected from that of arylacetamides in conferring κOR activities.

Mn oxides are the major sinks for Cd(II) in the aquatic environment. At the redox interface, reduced sulfur might affect the fate of sorbed Cd(II) by either reducing Mn oxides or forming strong complexes with Cd(II). Here, we investigated the fate of Cd(II) immobilized on δ-MnO 2 affected by reduced sulfur (S 2- and cysteine). A low concentration of S 2- led to Cd(II) migration from vacant sites to edge sites, while a high concentration of S 2- largely converted Cd(II) adsorbed on the surface of δ-MnO 2 to CdS. At low pH, the cysteine addition led to the release of Cd(II) initially adsorbed at the δ-MnO 2 vacant sites into the solution and caused the migration of a small portion of Cd(II) to the δ-MnO 2 edge sites. At high pH, a high concentration of cysteine led to the detachment of Cd(II) from δ-MnO 2 , Cd(II) readsorption by Mn(III)-bearing minerals, and Cd-cysteine formation. Changes of Cd(II) speciation were caused by δ-MnO 2 dissolution induced by reduced sulfur, the competition of generated Mn(II/III) for the adsorption sites, and the precipitation of Cd(II) with reduced sulfur. This study indicates that reduced sulfur is a critical factor controlling the fate of Cd(II) immobilized on Mn oxides in the aquatic environment.

In this study, iron selenide nanoparticles (FeSe 2 ) were synthesized and applied in Fenton-like reactions for degradation of pollutants. It was found that FeSe 2 exerts excellent catalytic reactivity toward different oxidants including peroxymonosulfate (PMS), peroxydisulfate, and H 2 O 2 , which can degrade a wide range of pollutants such as 2,4,4'-trichlorobiphenyl, bisphenol A, sulfamethoxazole, chlortetracycline, and perfluorooctanoic acid, with the degradation efficiency and TOC removal of pollutants reaching 55-95 and 20.3-50.9%, respectively. The mechanism of PMS activation by FeSe 2 was elucidated, and the synergistic effect between Fe and Se for PMS activation was discovered to be the dominant catalytic mechanism, as evidenced by free-radical quenching, electron paramagnetic resonance, and density functional theory studies. Briefly, the Fe(II) site on the FeSe 2 surface (111) accounted for PMS activation, while the reducing Se species on the surface not only acted as an electron donor contributing to Fe(II) regeneration but also produced Se vacancies further facilitating Fe(II) regeneration to improve the performance of PMS activation. In addition, FeSe 2 exhibited high catalytic activity and stability for PMS activation with different pH, and can degrade PCBs efficiently in the presence of anions, natural organic matter water matrices or in complex soil eluents. This study presents the development and evaluation of FeSe 2 as a novel and highly efficient activator that exhibits promise for practical applications for the degradation of pollutants in wastewater and soil wash eluent with Fenton-like reactions.