Weak Oxidation Research Articles

Combined administration of membrane-permeable and impermeable iron-chelating drugs attenuates ischemia/reperfusion-induced hepatic injury.

The underlying pathophysiological mechanisms of hepatic ischemia-reperfusion (I/R) injury have not been completely elucidated. However, it is well known that oxidative stress, caused by a burst of reactive oxygen species (ROS) production during the reperfusion phase, plays a crucial role. A growing body of evidence indicates that the intracellular availability of free iron represents a requirement for ROS-induced adverse effects, as iron catalyzes the generation of highly reactive free radicals. The aim of this study was to examine whether a combination of iron chelators with varying lipophilicity could offer enhanced protection against I/R by diminishing the conversion of weak oxidants, like H2O2, to extremely reactive ones such as hydroxyl radicals (HO.). HepG2 cells (hepatocellular carcinoma cell line) were exposed to oxidative stress conditions after pre-treatment with the iron chelators desferrioxamine (DFO) and deferiprone (DFP) alone or in combination. Labile iron pool was estimated using the calcein-acetoxymethyl ester (calcein-AM) method and DNA damage with the comet assay. We subsequently used a rabbit model (male New Zealand white rabbits) of hepatic I/R-induced injury to investigate, by measuring biochemical (ALT, ALT, ALP, γGT) and histological parameters, whether this may be true for in vivo conditions. The combination of a membrane-permeable iron chelator (DFP) with a strong membrane-impermeable one (DFO) raises the level of protection in both hepatic cell lines exposed to oxidative stress conditions and hepatic I/R rabbit model. Our results show that combinations of iron chelators with selected lipophilicity and iron-binding properties may represent a valuable strategy to protect against tissue damage during reperfusion after a period of ischemia.

Passivation of black phosphorus by triazine-based silica coating: Hierarchical BP@SiO2-N@Co(OH)2 structure for enhanced fire safety and toughness of unsaturated polyester resins

The fire and toxic smoke hazards of polymer combustion and the weak oxidation resistance of pure black phosphorus nanosheets (BPNSs) are hot and difficult issues. Here, triazinylsilane and Co(OH)2 nanoflowers are sequentially encapsulated on the surface of BPNSs to generate a novel multifunctional flame retardant (BP@SiO2-N@Co(OH)2), and incorporated into the unsaturated polyester resin (UPR). Specifically, with the addition of 2 wt% BP@SiO2-N@Co(OH)2, the nanocomposite exhibits superior thermal hazard suppression efficiency relative to previous related work. In particular, BP@SiO2-N@Co(OH)2 exhibits a superior ability to suppress toxic smoke than BPNSs, with a 42.3 % reduction in total smoke production (TSP) at 2 wt% flame retardant content. In addition, UPR with 0.5 wt% BP@SiO2@-N@Co(OH)2 achieves 76.5 % increases in impact strength, revealing excellent mechanical properties. Therefore, a novel multifunctional nano flame retardant is successfully synthesized and provided an innovative strategy for the preparation of multifunctional UPR nanocomposites.

Light-Initiated C–H Activation via Net Hydrogen Atom Transfer to a Molybdenum(VI) Dioxo

MoO2Cl2(bpy-tBu) (1) is shown to be a potent one-electron oxidant upon irradiation with 365 nm light in various solvents, while being a weak two-electron oxidant in the dark. Complex 1 is characterized to activate various types of C-H bonds photochemically, including allylic and benzylic positions as well as alkanes and aldehydes. In all of these oxidations, 1 ultimately forms a bimetallic Mo(V)/Mo(V) species with a μ-oxo ligand (2). Depending on the substrate, the major organic product is identified as either an oxygenated or a C-C coupled (homodimerized) compound along with a minor chlorinated species. The product selectivity is proposed to be dependent upon the relative values between the bond dissociation enthalpy (BDE) of a potentially new C-OH bond within the product versus the BDE of a Mo-OH motif within a Mo(V)O(OH) intermediate. Based on this, we can estimate the BDE for Mo-OH to be 83-93 kcal/mol. Mechanistic studies suggest that the C-H activation occurs via a net hydrogen atom transfer (HAT) from 1* occurring either asynchronously or via a stepwise electron-proton transfer (ET-PT) process. Complex 2 is further demonstrated to reform dioxo 1 in the presence of chemical oxidants.

OPPS Fibers with High Temperature Resistance and Excellent Antioxidant Properties by an Oxidation Method.

Polyphenylene sulfide (PPS) fiber products have been widely used for separation and filtration in harsh environments due to their excellent chemical resistance and relatively economical price. However, the poor temperature and weak oxidation resistance of PPS significantly shorten its service life under high temperature and strong oxidation environments. Herein, we report a type of oxidation-modified PPS (OPPS) fibers with excellent high temperature and oxidation resistance. This is achieved by oxidizing the thioether sulfide groups in PPS molecular chains into sulfoxide and sulfone groups and cross-linking the intermolecular chains. Both experiments and density functional theory (DFT) calculations indicate that hypochlorous acid (HClO) molecules can rapidly oxidize the PPS fiber surface. In addition, molecular dynamics (MD) simulations prove that there are strong hydrogen bonds and van der Waals interactions between HClO molecules and OPPS molecular chains, which promote the penetration of HClO molecules into the interior of the fiber to complete the layer-by-layer oxidation. The prepared OPPS-20 fibers exhibit excellent structural stability under high temperature and strong oxidant environments. Impressively, the OPPS-20 nonwoven filter still exhibits a high dust filtration efficiency of 99.95% after aging at 320 °C for 12 h, and the corresponding pressure drop is 24 Pa. In addition, the OPPS-20 nonwoven filter also maintains excellent filtration performance after aging in 60% HNO3 solution for 12 h, and the filtration efficiency and pressure drop are 99.96% and 29 Pa, respectively. This work demonstrates that the novel OPPS fibers have excellent application prospects in the field of separation and filtration in harsh environments.

Influence of matrix densification on the properties of weak matrix oxide fiber composites

The influence of the porosity on the mechanical properties of a Nextel™610/Al2O3-ZrO2 composite was investigated. The goal of the study was to determine the minimum porosity required for damage-tolerant behavior. To generate different porosities, the standard material was reinfiltrated with zirconium-n-butoxide up to seven times, thereby decreasing the open bulk porosity and the submicron porosity. The fiber- and matrix-dominated mechanical properties were investigated by three-point-bending with long and short beam samples. With decreasing porosity, the bending strength and strain dropped. A reduction from 46% to 37% in submicron porosity caused a loss of the damage-tolerant behavior of the samples. The Young’s modulus increased with every infiltration. The interlaminar shear strength showed a similar behavior but reached a maximum at 34% submicron porosity. Afterwards, it decreased as well due to the fibers acting as flaws.

TSR Action and Genesis Mechanism of Antimony Deposit: Evidence from Aromatic Hydrocarbon Geochemistry of Bitumen from Paleo-Oil Reservoir in Qinglong Ore Field, Southwestern Guizhou Depression, China

In Qinglong ore field, the paleo-oil reservoir is found to be associated with antimony deposits, and they have a close genetic relationship. In this study, the aromatics geochemistry of paleo-oil reservoir bitumen was studied to further discuss the thermochemical sulfate reduction (TSR) reaction and the mechanism of antimony mineralization. A total of 124 aromatic compounds were identified by gas chromatography–mass spectrometry (GC–MS) analysis in bitumen samples, including abundant phenanthrene series, dibenzothiophene series, fluoranthene series, chrysene series, and a small number of fluorene series, naphthalene series, dibenzofuran series, biphenyl series, and triaromatic steroid series. Aromatic parameters such as trimethylnaphthalene index (TMNr), methylphenanthrene index (MPI), methylphenanthrene distribution fraction (MPDF, F1, and F2), methyldibenzothiophene parameter (MDR), C28TAS-20S/(20R + 20S), and benzofluoranthene/benzo[e]pyrene indicate that the Qinglong paleo-oil reservoir is in over maturity level. The abundance of phenanthrene and chrysene aromatic compounds and a small amount of naphthalene series, benzofluoranthene, fluoranthene, pyrene, anthracene, retene, perylene, and biphenyl suggest that the organic matter source of the paleo-oil reservoir was mainly low aquatic organisms, mixed with a small amount of higher plant. They detected a certain number of compounds, such as retene, triaromatic steroid series, and perylene, the ternary diagram of DBF–DBT–F and binary plot of Pr/Ph–DBT/P, DBT/(F + DBT)–DBF/(F + DBF), and Pr/Ph–DBT/DBF reveal that the source rock of the paleo-oil reservoir was formed in the marine environment of weak oxidation and weak reduction. The comprehensive analysis shows that the Qinglong paleo-oil reservoir originated from Devonian source rocks, just like other paleo-oil reservoirs and natural gas reservoirs in the Nanpanjiang basin. Abundant dibenzothiophene series were detected, indicating that the paleo-oil reservoir underwent a certain degree of TSR reaction. We believe that the gas reservoir formed by the evolution of the oil reservoir in the ore field participated in antimony mineralization; that is, hydrocarbon organic matter acted as a reducing agent and transformed SO42− in oilfield brine into H2S through TSR, providing reduced sulfur and creating environmental conditions for mineralization.

Ethanolamine Derivatives Prompt Oxidation-Mediated Cleavage of Phosphorothioated DNA via Redox Control and Competition with Desulphurization

Abstract In the early 2000s, an epoch-making discovery of phosphorothioated DNA (PS-DNA, also as medicines) was made to show that sulfur atoms are present on the DNA backbone in microorganisms. However, its reaction activity and mechanism have not been well clarified. We show that PS-DNA is cleaved efficiently via oxidation, but not previously believed alkylation; this sulfur modification can be repaired by desulphurization once the sulfhydryl is further oxidized. When Tris or other ethanolamine derivatives are present, the cleavage becomes extremely efficient. Analyzed by enzymatic digestion, ligation, and mass spectroscopy, a mechanism is proposed to explain effects of ethanolamine derivatives and the competition between repair and breakage. Tris favors cleavage by keeping and utilizing the oxidation at –S(O)OH (sulfinic group) stage. The hydroxyl group on ethanolamine derivatives attacks the activated phosphor atom for cleavage with an intramolecular-like mode to form simultaneously a phosphoester bond. Desulphurization is dominant once the PS-DNA is oxidized to –S(O2)OH (sulfonic group). We believe that the biological significance of PS-DNA is protection of DNA nucleobases from weak oxidants by direct repairing or cleavage-repairing approach, which is affected by amines. Besides understanding the biological significance of PS-DNA, our findings will contribute greatly to developing new bio-techniques and nucleic acid medicines.

Review on g-C3N4-based S-scheme heterojunction photocatalysts

• Review of recent advances in g-C 3 N 4 -based S-scheme heterojunction photocatalysts. • The basic theory and preparation strategy of g-C 3 N 4 -based S-scheme heterojunctions are discussed. • The potential applications of g-C 3 N 4 S-scheme heterojunctions are reviewed. • The possible tendency of g-C 3 N 4 -based S-scheme heterojunctions is proposed. With the rapid development of economy and modern industry, serious environmental pollution and energy shortage have become major urgent challenges to the human society. Photocatalysis is a promising technology to provide green energy. As a typical metal-free polymer photocatalyst, g-C 3 N 4 has attracted more and more attention due to its excellent performance. Unfortunately, the fast recombination of photo-induced charges, limited light response range as well as weak oxidation ability are still the key drawback that restrict the photocatalytic performance of g-C 3 N 4 . These problems can be effectively addressed by constructing g-C 3 N 4 -based heterojunctions with two or more semiconductor materials, during which the respective advantages can be integrated. Up to now, the various oxidation semiconductor photocatalysts have been tried to construct the novel S-scheme heterojunction photocatalysts with g-C 3 N 4 . Thus, this review provides a comprehensive introduction of g-C 3 N 4 -based S-scheme heterojunctions, including the main characteristics of the S-scheme heterojunction, photocatalytic mechanisms, design rules and preparation methods of g-C 3 N 4 -based S-scheme heterojunction photocatalysts. Moreover, this review summarizes recently reported works on the potential applications of g-C 3 N 4 -based S-scheme photocatalysts in various important photocatalytic reactions, including photocatalytic hydrogen production, photocatalytic degradation of contaminants, photo-reduction of CO 2 into fuels, and photocatalytic sterilization. Finally, based on the current research progress, we propose some shortages in the preparation methods and applications of g-C 3 N 4 -based S-scheme heterojunctions, which are to be further investigated and resolved in this promising and creative research field.

Highly active crystal planes-oriented texture for reversible high-performance Zn metal batteries

Zn metal anodes with fast kinetics and stable thermodynamics is critical for developing reversible high-performance aqueous Zn-ion batteries. Herein, based on the characteristic of Zn hexagonal close-packed structure, a highly active reaction plane (HARP)-induced deposition strategy is developed by employing the selective reaction of weak oxidants ( e.g. , (NH 4 ) 6 Mo 7 O 24 ·4H 2 O) to crystal planes to build a thermodynamically stable ZnMoO 4 passivation layer on Zn metal surface. The selective reaction creates lots of lattice defects on the HARP as nuclei and orientation origin for Zn deposition showing the fast reaction kinetics. In addition, the ZnMoO 4 layer exhibits superior properties in inhibiting the corrosion and side reactions for Zn electrodes (stable thermodynamics), along with fast transport kinetics as uniform ion flux of Zn 2+ . Therefore, the Zn electrode delivers superb reversibility for stripping/plating over 6000 h with a low polarization of 40 mV at 0.5 mA cm −2 . This concept is universally valuable for constructing metal electrodes with fast kinetics, stable thermodynamics, and high-capacity.

Characteristics and main controlling factors of dolomite reservoirs in the Upper Cambrian Sanshanzi Formation, eastern Ordos Basin, China

The Cambrian system in the Ordos Basin has a similar development degree of carbonate strata to that in the Sichuan and the Tarim Basins; however, no significant oil and gas breakthroughs similar to those in the latter two basins have been made in the Ordos Basin yet, and the characteristics, genesis, and differences in the reservoir need to be explored. Field outcrop observations reveal that the oil and gas shows are common in the Upper Cambrian Sanshanzi Formation in the eastern Ordos Basin, indicating important oil and gas exploration potential. Analysis of the characteristics and genesis of dolomite reservoirs can greatly support the exploration and development of the Cambrian carbonate oil reservoirs in the Ordos Basin. Based on the field outcrop observations and comprehensive laboratory tests and analyses, the reservoir characteristics and main control factors are systematically discussed. This study reveals that the reservoir lithology mainly comprises crystalline dolomite, from fine crystalline dolomite to coarse crystalline dolomite; this results in reservoirs with low porosity, extreme-low porosity, and ultralow permeability dominated by intergranular denudation, caves, and microfractures. They can be further divided into two types of reservoirs: type I reservoirs that have low porosity, ultralow permeability, and medium pore-throat radii, and type II reservoirs that have extreme-low porosity, ultralow permeability, and small pore-throat radii. The physical properties of fine-medium crystalline and medium crystalline dolomite reservoirs are slightly better, and the throats tend to be larger with increasing grain size. The reservoirs have not experienced deep burial processes; dolomitization mainly occurs in the marine-sourced fluid environment with weak oxidation and weak reduction, influenced by the atmospheric fresh water and thermal fluid transformation during the late period to some extent, whereas the hydrocarbons mainly charged during the late period. The crystalline dolomite in residual grains superimposes the denudation and cataclasis in the epigenetic karst stage that are the main controlling factors of the reservoirs. The crystalline cataclasis of dolomite can aid in the formation and reconstruction of the reservoirs. The spatial and temporal distribution laws of the reservoirs and key formation periods need to be studied further.

Unconventional Photoconversion from In‐Plane 2D Heterostructures of 2D Transition Metal Carbides/Semiconductors

2D transition metal carbides/nitrides (MXenes) are thought of promising photothermal materials due to their broadband localized surface plasma resonance (LSPR) and attractive electromagnetic interference (EMI) properties. However, the weak oxidation resistance and unclear photothermal mechanism of MXenes impede their photothermal modulations. Herein, the in‐plane 2D Ti3C2/TiO2 heterostructures are fabricated by partial oxidation and an unconventional photothermal effect under near infrared irradiation, even if the oxidation compromises the EMI and LSPR capacities, is demonstrated. Such performance is ascribed to the faster transfer of photoexcited electrons across the seamless in‐plane Ti3C2/TiO2 heterointerface than the reported out‐of‐plane one, and the 1–2 orders of magnitude faster relaxation processes of electrons than the ground bleaching in the Original MXene. These experimental results are well‐supported by theoretical calculations. The conceptual advances broaden the fundamental understanding of the photoconversion of MXenes, which would be extended into a variety of applications, such as biomedical therapy, photosynthesis, and photovoltaics.

Z-scheme heterojunctions with double vacancies semiconductors MoO3−x and Fe-doped W18O49 for photocatalytic nitrogen fixation

Ammonia gas has important application value in many fields. However, a large amount of energy is consumed to prepare ammonia by the Haber-Bosch process. A cleaner catalytic way to prepare ammonia has become a common goal of human beings. In this paper, Z-scheme heterojunction MoO3−x/Fe-W18O49 was prepared by two-step solvothermal method. The prepared MoO3−x is a flower-like structure formed by the stacking of nanosheets, which can be applied as the attachment carrier of Fe-W18O49 nanowires to effectively inhibit the aggregation of nanowires. Therefore, Fe-W18O49 nanowires will have more oxygen vacancies (OVs) on the surface of the catalyst as the active center of the reaction. MoO3-x containing OVs has LPSR effect, which can enlarge the light absorption range of the heterojunction. In addition, the vacancies contained in MoO3−x can promote the recombination of weak reducing electrons and weak oxidation holes. The catalyst MoO3−x/Fe-W18O49 exhibits strong redox capacity, which is conducive to the occurrence of nitrogen fixation reaction. Under the simulated sunlight condition, the ammonia production rate reached 137.5 µmol g−1 h−1 without any sacrificial reagent. MoO3−x/Fe-W18O49 has good catalytic performance and stability. This work has a certain reference value for the construction of efficient heterojunction catalyst for photocatalytic nitrogen fixation.

Molecular dynamics simulation and experimental study of tin growth in SAC lead-free microsolder joints under thermo-mechanical-electrical coupling

Sn-Ag-Cu system lead-free solders are considered to be promising solder series. The growth of Sn whiskers on the solder surface is an important factor that threatens the reliability of electronic products. In this study, the IMC evolution and whiskers growth of Sn-0.3Ag-0.7Cu (SAC0307) microsolder joints under thermal-mechanical-electrical coupling were investigated by the combination of molecular dynamics simulation and experimental methods. The simulation and experimental results revealed that the electric field intensity had the greatest influence on the atomic diffusion. When the electric field intensity was 0.004 V/Å, the diffusion speed of copper atom to solder reached the maximum, and the intermetallic compounds Cu6Sn5 and Cu3Sn were formed at the interface, which provided the long-term driving force for the growth of tin whiskers at the weak oxide film on the surface. Tin whiskers were inclined to grow at the anode, while holes and cracks were tend to produce at the cathode. When the external pressure stress was 0.03 nN, most of tin atoms were precipitated. When the temperature was 393 K, the whiskers slowly grew to 3.3 µm in length at the growth rate of 0.0182 Å/s. The results can provide the basis for the growth mechanism of tin whisker in real service situations.

Intermittent electric field stimulated reduction-oxidation coupled process for enhanced azo dye biodegradation

The electro-stimulated microbial process offers promise in overcoming the intrinsic drawbacks of the conventional reduction–oxidation process for azo dyes removal. However, the lack of available electron donors, continuous external power supply, and weak anodic oxidation are the major challenges for this process to achieve efficient azo dye biodegradation. Herein, an intermittent electric field stimulated reduction–oxidation coupled process was developed to enhance Alizarin Yellow R (AYR) biodegradation. Introducing a weak intermittent electrostimulation considerably boosted the anaerobic cathodic reduction and micro-oxygen-assisted anodic oxidation process, as evidenced by the higher AYR decolorization, p-phenylenediamine, and 5-aminosalicylic acid bio-mineralization efficiency than that in the bio-processes with continuous and without electrostimulation, respectively. The endogenous organics generated during AYR degradation could serve as an effective electron source for anodic microorganisms to drive the biocathode decolorization. Compared to continuous electrostimulation, intermittent electrostimulation exhibited better electron transfer capability and created a more favorable oxidation–reduction potential (ORP) for reductive decolorization of AYR and bio-mineralization of its intermediate products. Microbial community analysis revealed that more functional consortia capable of electroactivity (e.g. Geobacter and Pseudomonas) and AYR metabolism (e.g. Bosea, Sphingopyxis, and Achromobacter) were enriched by intermittent electrostimulation than continuous electrostimulation. The molecular ecological network analysis indicated that synthetic metabolisms between electroactive and AYR metabolizing bacteria might play major roles in electro-microbial-mediated AYR removal. This study reveals the potential and mechanism of intermittent electric field stimulated reduction–oxidation coupled process for enhanced azo dye biodegradation, which opens an appealing avenue for enhanced azo dye removal from wastewater.

Managing the Redox Potential of PCET in Grotthuss-Type Proton Wires.

Expanding proton-coupled electron transfer to multiproton translocations (MPCET) provides a bioinspired mechanism to transport protons away from the redox site. This expansion has been accomplished by separating the initial phenolic proton donor from the pyridine-based terminal proton acceptor by a Grotthuss-type proton wire made up of concatenated benzimidazoles that form a hydrogen-bonded network. However, it was found that the midpoint potential of the phenol oxidation that launched the Grotthuss-type proton translocations is a function of the number of benzimidazoles in the hydrogen-bonded network; it becomes less positive (i.e., a weaker oxidant) as the number of bridging benzimidazoles increases. Herein, we report a strategy to maintain the high redox potential necessary for oxidative processes relevant to artificial photosynthesis, e.g., water oxidation and long-range MPCET processes for managing protons. The integrated structural and functional roles of the benzimidazole-based bridge provide sites for substitution of the benzimidazoles with electron-withdrawing groups (e.g., trifluoromethyl groups). Such substitution increases the midpoint potential of the phenoxyl radical/phenol couple so that proton translocations over ∼11 Å become thermodynamically comparable to that of an unsubstituted system where one proton is transferred over ∼2.5 Å. The extended, substituted system maintains the hydrogen-bonded network; infrared spectroelectrochemistry confirms reversible proton translocations from the phenol to the pyridyl terminal proton acceptor upon oxidation and reduction. Theory supports the change in driving force with added electron-withdrawing groups and provides insight into the role of electron density and electrostatic potential in MPCET processes associated with these Grotthuss-type proton translocations.

Effects of flue gas components on CrOOH adsorption by γ-Al2O3 during municipal solid waste incineration based on DFT analysis

Cr pollutants released during the incineration of municipal solid waste (MSW) are volatile, biotoxic and pose carcinogenic risks under long-term exposure. In this study, density functional theory (DFT) was used to examine the impacts of flue gas components (FGCs) on CrOOH adsorption by γ-Al2O3. The investigated FGCs included O2, HCl, SO2, H2O, and CO2.The impacts of FGCs on the average adsorption energy of CrOOH by γ-Al2O3 were ranked as: O2 > SO2 > H2O > HCl > CO2. The effects of FGCs on CrOOH adsorption were manifested by oxidation, electron transfer and competitive adsorption. O2 promoted the adsorption of CrOOH on γ-Al2O3 due to oxidation effect and electron transfer effect. SO2 and H2O presented an electron transfer effect and weak oxidation effect, which limited their ability to promote CrOOH adsorption by γ-Al2O3. The competitive adsorption effects of HCl and CO2 were dominant and inhibited CrOOH adsorption by γ- Al2O3. The simulation results explained the role of FGCs on CrOOH capture by γ-Al2O3 and provided guidance for chromium control.

Effects of Annealing and Thickness of Co60Fe20Yb20 Nanofilms on Their Structure, Magnetic Properties, Electrical Efficiency, and Nanomechanical Characteristics

X-ray diffraction (XRD) analysis showed that metal oxide peaks appear at 2θ = 47.7°, 54.5°, and 56.3°, corresponding to Yb2O3 (440), Co2O3 (422), and Co2O3 (511). It was found that oxide formation plays an important role in magnetic, electrical, and surface energy. For magnetic and electrical measurements, the highest alternating current magnetic susceptibility (χac) and the lowest resistivity (×10−2 Ω·cm) were 0.213 and 0.42, respectively, and at 50 nm, it annealed at 300 °C due to weak oxide formation. For mechanical measurement, the highest value of hardness was 15.93 GPa at 200 °C in a 50 nm thick film. When the thickness increased from 10 to 50 nm, the hardness and Young’s modulus of the Co60Fe20Yb20 film also showed a saturation trend. After annealing at 300 °C, Co60Fe20Yb20 films of 40 nm thickness showed the highest surface energy. Higher surface energy indicated stronger adhesion, allowing for the formation of multilayer thin films. The optimal condition was found to be 50 nm with annealing at 300 °C due to high χac, strong adhesion, high nano-mechanical properties, and low resistivity.

Geochemical Speciation, Risk Assessment, and Sources Identification of Heavy Metals in Mangrove Surface Sediments from the Nanliu River Estuary of the Beibu Gulf, China

To better understand heavy metal pollution and the potential ecological risk of mangrove sediments in the Nanliu River estuary, the speciation and distribution characteristics of heavy metals Fe, Mn, Zn, Co, Ni, Cd, Cr, Cu, and Pb in 13 surface sediments in the study area were determined and analyzed using a modified four-step BCR extraction method, and the ecological risk of heavy metals was assessed using the Geo-accumulation Index (Igeo), Potential Ecological Risk Index (RI), Risk Assessment Code (RAC), Pollution Load Index (PLI), Individual contamination factors (ICF) and Global contamination factor (GCF) methods, and source analyses were performed using correlation analysis and cluster analysis. The results showed that the heavy metal was in the order of Fe > Mn > Cu > Zn > Cr > Pb > Co > Ni > Cd. Except for Fe, Zn, Ni, Cr, Pb, and Co, the average heavy metal content of Mn, Cd, and Cu all exceeded the environmental background value; the Fe, Zn, Co, Ni, Cr, Cu, and Pd are mainly in the residual speciation, while Mn and Cd are mainly weak acid extraction and oxidation, respectively, both of which are predominantly in unstable speciation and are easily released into the environment. Mn and Cd pose a substantial ecological risk, while Cu and Pb present a moderate risk and require precaution. The source analysis results indicate that Fe, Mn, Zn, Ni, Cr, and Pb are most likely to originate from natural sources and the transportation industry, Co and Cu are likely to be mainly from ship manufacturing industrial activities, and Cd is likely to be mainly from agriculture and aquaculture. The GCF and PLI results show that places with high heavy metal enrichment and ecological risk are primarily located in areas with high industrial, agricultural, or human activity impacts.

Nanozymes-engineered metal–organic frameworks for enhanced microwave thermodynamic therapy in PDX of hepatic carcinoma

Dynamic therapy (DT) has emerged as a promising cancer therapy due to its non-invasive treatment and good spatiotemporal control. However, the efficiency of DT is restricted by several limitations, including insufficient oxygen supply, high expression of pre-tumor factors (e.g., vascular endothelial growth factor, VEGF), and insufficient and relatively weak oxidation ability of reactive oxygen species (ROS) generation. Herein, we propose an in-situ enzyme-like cascade catalysis therapeutic strategy for enhanced MW thermodynamic therapy. The as-prepared nanozymes-engineered metal–organic frameworks (Apatinib@ZIF67@PDA, AZP NCs nanozymes) achieve excellent therapeutic effects in a patient-derived xenograft (PDX) model of hepatic carcinoma. Precisely, after intravenous administration, the ZIF structure of AZP NCs nanozymes is disrupted in the acidic tumor microenvironment, which results in the release of Co (II) and the antiangiogenic agent of Apatinib (AP). Subsequently, Co (II) disproportionates H2O2 into highly oxidizing hydroxyl radicals (•OH) and Co (III). Meanwhile, Co (III) combined with MW can effectively alleviate tumor hypoxia by catalyzing the intratumoral H2O2 to O2, and enhance the generation of ROS. Moreover, the release of AP can downregulate the expression of VEGF, thus effectively inhibiting the tumor angiogenesis after MW thermodynamic therapy. Hence, tumor cells are eliminated completely under the action of MW thermodynamic therapy cooperative combination of AP by AZP NCs nanozymes. This work presents a catalytic strategy for MOF-based nanozymes to improve DT efficiency and provides a new insight for highly efficient anticancer approaches.

Physicochemical and Colon Cancer Cell Inhibitory Properties of Theabrownins Prepared by Weak Alkali Oxidation of Tea Polyphenols.

Existing studies on the biological activity of theabrownins are not based on their free state but on the complexes of theabrownins, polysaccharides, proteins, and flavonoids. In this study, theabrownins (TBs-C) were prepared by weak alkali oxidation of tea polyphenols. The ultraviolet-visible scanning spectrum of TBs-C showed two characteristic absorption peaks at 203 and 270nm. The zeta potential of the TBs-C aqueous solution was negative, and the values varied from - 6.26 to -19.55 mV with a solution pH of 3-9. Storage conditions of pH 5.0-7.0 and around 25°C were beneficial for the physical and chemical stability of the TBS-C solution. Cells were treated with series concentrations and examined by MTT, HE staining, PI immunofluorescence staining, flow cytometry, and real-time PCR to investigate the antiproliferative effect of TBs-C on human colon cancer HT-29 cells. The results showed that TBs-C, particularly at 500µg/mL, inhibited cell growth. TBs-C induced HT-29 cell apoptosis, as confirmed by morphological changes, nucleus propidium iodide staining, and distributions of the cell cycle. The apoptotic mechanism may be due to the intracellular redox imbalance induced by TBs-C.