Deeper Defluorination and Mineralization of a Novel PFECA (C7 HFPO-TA) in Vacuum UV/Sulfite: Unique Mechanism of H/OCF₃ Exchange

C7 HFPO-TA is a newly identified alternative to PFOA, which possesses a unique structure fragment (CF3O–CF(CF3)−). In this study, we evaluated the chemical reactivity of C7 HFPO-TA in advanced oxidation and reduction processes for the first time, which revealed a series of unexpected transformation mechanisms. The results showed that reductive degradation based on hydrated electrons (eaq–) was more feasible for the degradation of C7 HFPO-TA. For oxidative degradation, the branched −CF3 at the α-position carbon posed as the spatial hindrance, shielding the attack of SO4•– to −COO–. The synergistic effects of HO•/eaq– and direct photolysis led to deeper defluorination and mineralization of C7 HFPO-TA in the vacuum UV/sulfite (VUV/SF) process. We identified a unique H/OCF3 exchange that converted the CF3O–CF(CF3)- into H–CF(CF3)- directly, and the SO3•– involved mechanism of C7 HFPO-TA for the first time. We revealed the branched −CF3 connected to the same carbon next to the CF3O- group affected the C–O bond cleavage site, preferring the H/OCF3 exchange pathway. The defluorination of C7 HFPO-TA was compared with PFOA and three PFECAs in the VUV/SF process, which was highly dependent on structures. Degradation kinetics, theoretical calculations, and products’ analysis provided an in-depth perspective on the degradation mechanisms and pathways of C7 HFPO-TA

Tailoring the properties of a zero-valent iron-based composite by mechanochemistry for nitrophenols degradation in wastewaters

<p>Zero-valent iron (ZVI) is a valuable material for environmental remediation, because of its safeness, large availability, and inexpensiveness. Moreover, its reactivity can be improved by addition of (nano-) particles of other elements such as noble metals. However, common preparation methods for this kind of iron-based composites involve wet precipitation of noble metal salt precursors, so they are often expensive and not green. Mechanochemical procedures can provide a solvent-free alternative, even at a large scale. The present study demonstrates that it is possible to tailor functional properties of ZVI-based materials, utilizing high-energy ball milling. All main preparation parameters are investigated and discussed. Specifically, a copper-carbon-iron ternary composite was prepared for fast degradation of 4-nitrophenol (utilized as model pollutant) to 4-aminophenol and other phenolic compounds. Copper and carbon are purposely chosen to insert specific properties to the composite: Copper acts as efficient nano-cathode that enhances electron transfer from iron to 4-nitrophenol, while carbon protects the iron surface from fast oxidation in open air. In this way, the reactive material can rapidly reduce high concentration of nitrophenols in water, it does not require acid washing to be activated, and can be stored in open air for one week without any significant activity loss.</p

Table_2_Dietary curcumin supplementation can enhance health and resistance to ammonia stress in the greater amberjack (Seriola dumerili).xlsx

We evaluated the effect of dietary curcumin supplementation on the antioxidant capacity of the liver and the resistance of the liver and spleen to ammonia stress in the great amberjack (Seriola dumerili). Three isonitrogenous and isolipidic test diets were prepared by supplementing incremental levels of dietary curcumin at 0 mg/kg (CUR0%, control), 100 mg/kg (CUR0.01%), and 200 mg/kg (CUR0.02%), respectively. Each diet was randomly assigned to triplicate groups of 15 fish per tank. At the end of the feeding experiment, dietary curcumin supplementation positively modulated antioxidant-related genes and enzyme activity in liver tissues. After the ammonia challenge, dietary supplementation with the appropriate level of curcumin alleviated ammonia stress in liver tissue by upregulating the relative expression of GSH-Px and downregulating the relative expression of Keap1 and GR. Meanwhile, ammonia stress in spleen tissue could also be alleviated by upregulating the relative expression of CAT, downregulating the relative expression of GR, and increasing the activity of SOD and GSH. After the recovery, dietary supplementation with curcumin still alleviated ammonia stress in the liver tissue by upregulating the relative expression of CAT, downregulating the relative expression of Keap1 and GR, and increasing the activity of SOD and GSH. On the other hand, ammonia stress in spleen tissue was still alleviated by upregulating the relative expression of Mn-SOD and increasing the activity of SOD and GSH. The histological structure results also showed that liver cells in the curcumin-containing groups exhibited a positive impact on cell boundaries, alignment, and nuclei after the ammonia challenge and recovery. Spleen cells in the curcumin-containing groups exhibited greater aggregation of melano-macrophage centers after the ammonia challenge and recovery. These results suggest that dietary curcumin supplementation at 100 mg/kg can promote the health condition and resistance to ammonia stress of the greater amberjack.</p

Table_1_Dietary curcumin supplementation can enhance health and resistance to ammonia stress in the greater amberjack (Seriola dumerili).xlsx

We evaluated the effect of dietary curcumin supplementation on the antioxidant capacity of the liver and the resistance of the liver and spleen to ammonia stress in the great amberjack (Seriola dumerili). Three isonitrogenous and isolipidic test diets were prepared by supplementing incremental levels of dietary curcumin at 0 mg/kg (CUR0%, control), 100 mg/kg (CUR0.01%), and 200 mg/kg (CUR0.02%), respectively. Each diet was randomly assigned to triplicate groups of 15 fish per tank. At the end of the feeding experiment, dietary curcumin supplementation positively modulated antioxidant-related genes and enzyme activity in liver tissues. After the ammonia challenge, dietary supplementation with the appropriate level of curcumin alleviated ammonia stress in liver tissue by upregulating the relative expression of GSH-Px and downregulating the relative expression of Keap1 and GR. Meanwhile, ammonia stress in spleen tissue could also be alleviated by upregulating the relative expression of CAT, downregulating the relative expression of GR, and increasing the activity of SOD and GSH. After the recovery, dietary supplementation with curcumin still alleviated ammonia stress in the liver tissue by upregulating the relative expression of CAT, downregulating the relative expression of Keap1 and GR, and increasing the activity of SOD and GSH. On the other hand, ammonia stress in spleen tissue was still alleviated by upregulating the relative expression of Mn-SOD and increasing the activity of SOD and GSH. The histological structure results also showed that liver cells in the curcumin-containing groups exhibited a positive impact on cell boundaries, alignment, and nuclei after the ammonia challenge and recovery. Spleen cells in the curcumin-containing groups exhibited greater aggregation of melano-macrophage centers after the ammonia challenge and recovery. These results suggest that dietary curcumin supplementation at 100 mg/kg can promote the health condition and resistance to ammonia stress of the greater amberjack.</p

Composition-Tunable PtCu Alloy Nanowires and Electrocatalytic Synergy for Methanol Oxidation Reaction

The ability to impart Pt-based catalysts with high catalytic activity and low cost is essential for advancing fuel cell technologies. This report describes the synthesis of composition-tunable PtCu alloy nanowires (NWs) of ultrathin diameters (ca. 1 nm) to create synergistic catalytic sites along the nanowire surfaces. The bimetallic NWs exhibit composition-tunable fcc-type alloy phase. The electrocatalytic properties of the PtCu alloy NWs for methanol oxidation reaction were shown to display an intriguing composition-dependent catalytic synergy. The maximum mass activity for Pt₃₂Cu₆₈ NWs was about 2 times higher than that of Pt NWs. It also exhibited the highest stability and tolerance to CO poisoning. The enhanced activity and stability were attributed to a bifunctional synergy whereby the alloyed Cu atoms in the Pt lattice provides CO-maneuvering sites for reducing the poisoning effect of CO intermediate species on the active surface sites of the NWs

Synthesis of Ultralong, Monodispersed, and Surfactant-Free Gold Nanowire Catalysts: Growth Mechanism and Electrocatalytic Properties for Methanol Oxidation Reaction

The understanding of factors influencing the growth of nanowires is critical for the precise control of the nanowire morphologies and the design of active nanowire catalysts for fuel cell reactions. While the formation of gold nanoparticles followed by self-assembly into short strings of nanowires is known, little is understood in terms of the control of the morphologies and surface properties toward enhanced electrocatalytic properties. This report describes novel findings of an investigation of the growth mechanism of ultralong, highly monodispersed, and surface surfactant-free gold nanowires (Au NWs) synthesized by a galvanic replacement reaction of Te NWs as an initial template. By manipulating reaction time and Au precursor concentration, an aggregative growth mechanism in terms of 1D and 3D growth pathways for the NW length and diameter, respectively, is revealed to be operative in the template-directed Au NW formation process, shinning some fresh insight into the controllability of the nanowire morphologies. In contrast to the use of various organic surfactants in most previous synthesis of Au NWs and catalysts, the surfactant-free Au NWs synthesized in this work have been demonstrated to exhibit enhanced electrocatalytic activities for methanol oxidation reaction, outperforming those for Au NWs with surface surfactants and Au NP counterparts

Polyethylenimine-Impregnated Resin for High CO₂ Adsorption: An Efficient Adsorbent for CO₂ Capture from Simulated Flue Gas and Ambient Air

Polyethylenimine (PEI)-impregnated resins with high CO₂ adsorption capacity were successfully prepared in this study. The nonpolar resin HP20 was suitable for PEI loading to achieve high CO₂ adsorption, and the optimal PEI loading was 50 wt %. On the basis of the pore-size distribution of the resin before and after PEI modification, it can be found that mesopores of <43 nm were mainly responsible for PEI loading and pores in the range of 43–68 nm were probably favorable for CO₂ diffusion. The adsorbed amount of CO₂ on HP20/PEI-50 decreased with increasing adsorption temperature because of the dominant role of exothermic reaction of CO₂ adsorption. The adsorption of CO₂ on the adsorbent was very fast, and sorption equilibrium was achieved within 6 min at 75 °C. HP20/PEI-50 almost kept a stable adsorption capacity for CO₂ at concentrations of 15 vol % and 400 ppm in the consecutive adsorption–desorption cycles, and its adsorption capacity was 181 mg/g from pure CO₂ and 99.3 mg/g from 400 ppm CO₂ at 25 °C, higher than all PEI-modified materials reported. The high volume-based amount of CO₂ adsorbed on HP20/PEI-50 (96.0 mg/cm³ at 25 °C and 84.5 mg/cm³ at 75 °C for pure CO₂) is beneficial to reducing the required volume of the adsorption bed for CO₂ capture. This spherical and stable HP20/PEI-50 adsorbent with high and fast CO₂ adsorption exhibits a very promising application in CO₂ capture from flue gas and ambient air

Understanding the Adsorption of PFOA on MIL-101(Cr)-Based Anionic-Exchange Metal–Organic Frameworks: Comparing DFT Calculations with Aqueous Sorption Experiments

To examine the effects of different functionalization methods on adsorption behavior, anionic-exchange MIL-101­(Cr) metal–organic frameworks (MOFs) were synthesized using preassembled modification (PAM) and postsynthetic modification (PSM) methods. Perfluorooctanoic acid (PFOA) adsorption results indicated that the maximum PFOA adsorption capacity was 1.19 and 1.89 mmol g^–1 for anionic-exchange MIL-101­(Cr) prepared by PAM and PSM, respectively. The sorption equilibrium was rapidly reached within 60 min. Our results indicated that PSM is a better modification technique for introducing functional groups onto MOFs for adsorptive removal because PAM places functional groups onto the aperture of the nanopore, which hinders the entrance of organic contaminants. Our experimental results and the results of complementary density functional theory calculations revealed that in addition to the anion-exchange mechanism, the major PFOA adsorption mechanism is a combination of Lewis acid/base complexation between PFOA and Cr­(III) and electrostatic interaction between PFOA and the protonated carboxyl groups of the bdc (terephthalic acid) linker

Ultrathin Copper Nanowire Synthesis with Tunable Morphology Using Organic Amines for Transparent Conductors

High-quality monodispersed copper nanowires with an ultrathin diameter of 13.5 nm, lengths up to 30 μm (aspect ratio >10⁴) were successfully synthesized by a facile and controllable hydrothermal reduction procedure. The synthesis utilized glucose in the presence of hexadecylamine (HDA) and octadecylamine (ODA) as the capping agents. The copper decahedra nanoparticles with a low-surface-energy {111} plane formed pentatwinned one-dimensional nanowires, which was exactly verified by selected-area electron diffraction. Furthermore, the diameter and relative film conductivity of copper nanowires are sensitive to the HDA/ODA molar ratio. The conductor film made of the high-quality and ultrathin copper nanowires shows high transmittance and low resistance (83.83%, 61 Ω/□), exhibiting great potential in the applications of nanofabrication, transparent and flexible conductors, organic light-emitting diodes, and more

Supplementary document for On-chip Multi-trap Optical Tweezers Based on Guided Wave–Driven Metalens - 6867705.pdf

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