Harnessing bacteria for superoxide production in bioremediation holds immense promise,yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide.This study...Harnessing bacteria for superoxide production in bioremediation holds immense promise,yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide.This study delves into a cost-effective approach to amplify superoxide production using an Arthrobacter strain,a prevalent soil bacterial genus.Our research reveals that introducing a carbon source along with specific iron-binding ligands,including deferoxamine(DFO),diethylenetriamine pentaacetate(DTPA),citrate,and oxalate,robustly augments microbial superoxide generation.Moreover,our findings suggest that these iron-binding ligands play a pivotal role in converting superoxide into hydroxyl radicals by modulating the electron transfer rate between Fe(Ⅲ)/Fe(Ⅱ)and superoxide.Remarkably,among the tested ligands,only DTPA emerges as a potent promoter of this conversion process when complexed with Fe(Ⅲ).We identify an optimal Fe(Ⅲ)to DTPA ratio of approximately 1:1 for enhancing hydroxyl radical production within the Arthrobacter culture.This research underscores the efficacy of simultaneously introducing carbon sources and DTPA in facilitating superoxide production and its subsequent conversion to hydroxyl radicals,significantly elevating bioremediation performance.Furthermore,our study reveals that DTPA augments superoxide production in cultures of diverse soils,with various soil microorganisms beyond Arthrobacter identified as contributors to superoxide generation.This emphasizes the universal applicability of DTPA across multiple bacterial genera.In conclusion,our study introduces a promising methodology for enhancing microbial superoxide production and its conversion into hydroxyl radicals.These findings hold substantial implications for the deployment of microbial reactive oxygen species in bioremediation,offering innovative solutions for addressing environmental contamination challenges.展开更多
P450 enzymes-catalyzed aromatic hydroxylation plays an important role in detoxification,biosynthesis,and potential carcinogenic effect of aromatic compounds.Though it has been explored for decades,the actual process o...P450 enzymes-catalyzed aromatic hydroxylation plays an important role in detoxification,biosynthesis,and potential carcinogenic effect of aromatic compounds.Though it has been explored for decades,the actual process of aromatic hydroxylation and mechanism of regioselectivity catalyzed by cytochrome P450 monooxygenases remained ambiguous.Here,we have resolved these issues.With a stable chiral organofluorine probe,and especially with X-ray data of two isolated arene oxides derivatives,we demonstrate that an arene oxide pathway is definitely involved in P450-catalyzed aromatic hydroxylation.By the capture,isolation,identification and reactivity exploration of the arene 1,2-oxide and arene 2,3-oxide intermediates,together with advanced QM calculations,the mechanism of how two intermediates go to the same product has been elucidated.In addition to the model substrate,we also confirmed that an arene oxide intermediate is involved in the P450-catalyzed hydroxylation pathway of a natural product derivative methyl cinnamate,which indicates that this intermediate appears to be universal in P450-catalyzed aromatic hydroxylation.Our work not only provides the most direct evidence for the arene oxide pathway and new insights into the regioselectivity involved in P450-catalyzed aromatic hydroxylation,but also supplies a new synthetic approach to achieve the dearomatization of aromatic compounds.展开更多
Achieving sustainable energy and chemical production has become an important issue for human society.Photocatalysis has attracted much attention due to its ability to harness solar energy to drive chemical reactions.M...Achieving sustainable energy and chemical production has become an important issue for human society.Photocatalysis has attracted much attention due to its ability to harness solar energy to drive chemical reactions.Metal sulfide-based photocatalysts(e.g.,Cd S,Zn In2S4)have shown substantial potential in biomass-based hydroxyl compound valorization.In this review,we summarize the recent progress in metal sulfide-based photocatalysts for the photo upgrading of biomass-derived hydroxyl compounds coupled with reduction reactions(e.g.,CO_(2)reduction,H_(2)O_(2)generation,and H_(2)evolution).The mechanism of biomass redox reactions is discussed,highlighting the potential of realizing the valorization of biomass-derived compounds coupled with the reduction reactions,which is beneficial for researchers to actively explore biomass biorefinery pathways in order to modulate the selectivity of the valueadded products.Various modification strategies are presented,including elemental doping,defect engineering,heterojunction construction,and cocatalyst loading.These strategies modulate the energy band structure,surface electron density,and built-in electric field strength of metal sulfide-based photocatalysts,thereby enhancing their photocatalytic performance.The challenges and prospects of metal sulfidebased photocatalysts in biomass valorization are analyzed.This approach contributes to the development of photocatalysts that can accelerate biomass photo-upgrading coupling reactions.This review aims to provide deeper insights into the photocatalytic biorefinery pathways and contribute to the development of functionalized photocatalysts that can accelerate biomass photo upgrading,highlighting the synergistic effects of multiple coupling reactions.展开更多
Addressing inadequate OH^(*)adsorption in Ru Co alloy catalysts is crucial for boosting intermediate coverage and redirecting the water-splitting pathway.Herein,the adaptive P sites were strategically incorporated to ...Addressing inadequate OH^(*)adsorption in Ru Co alloy catalysts is crucial for boosting intermediate coverage and redirecting the water-splitting pathway.Herein,the adaptive P sites were strategically incorporated to overcome the aforementioned challenge.The P sites,as potent OH^(*)adsorption centers,synergize with Co sites to promote water dissociation and enrich surrounding Ru sites with H*intermediates,thus triggering the Volmer-Tafel route for hydrogen evolution reaction(HER).Besides,during the oxygen evolution reaction(OER),the surface of P-Ru Co was reconstructed into Ru-doped Co OOH with anchored PO_(4)^(3-).These PO_(4)^(3-)not only circumvent the intrinsic OH^(*)adsorption limitations of Ru-Co OOH in the adsorbate evolution mechanism(AEM)by rerouting to a more expeditious lattice oxygen oxidation mechanism(LOM)but also improve the coverage of key oxygen-containing intermediates,significantly accelerating OER kinetics.Consequently,the P-Ru Co demonstrates exceptional bifunctional performance,with overpotentials of 29 m V for HER and 222 m V for OER at 10 m A cm^(-2).Remarkably,the mass activities of PRu Co for HER(5.48 A mg^(-1))and OER(2.13 A mg^(-1))are 6.2 and 11.2 times higher than those of its commercial counterparts(Ru/C for HER and RuO_(2)for OER),respectively.When integrated into an anionexchange-membrane electrolyzer,this catalyst achieves ampere-level current densities of 1.32 A cm^(-2)for water electrolysis and 1.23 A cm^(-2)for seawater electrolysis at 2.1 V,with a 500-h durability.展开更多
UiO-66-H MOFs can effectively catalyze the direct selective oxidation of methane(DSOM)to high value-added oxygenates under mild conditions.However,UiO-66-NH_(2)with benzene-1,4-dicarboxylate(NH_(2)-BDC)ligand modifyin...UiO-66-H MOFs can effectively catalyze the direct selective oxidation of methane(DSOM)to high value-added oxygenates under mild conditions.However,UiO-66-NH_(2)with benzene-1,4-dicarboxylate(NH_(2)-BDC)ligand modifying the Zr-oxo nodes exhibits relatively inferior catalytic performance for DSOM.Here,a combination of density functional theory(DFT)calculations and experiments was employed to explore the underlying reasons for the limited catalytic activity of UiO-66-NH_(2).The results indicate that the methane hydroxylation performance of UiO-66-NH_(2)is almost unaffected by the increase of·OH concentration.This is attributed to the formation of substantial non-covalent hydrogen bonds between the oxygen atoms of oxygenic species on the Zr-oxo nodes and the hydrogen atoms of-NH_(2)groups,which diminishes the spin density distribution on the active sites of(·OH)m/UiO-66-NH_(2),leading to minimal change of the adsorption energy of CH_(4).Additionally,the calculated adsorption energies(Eads)of CH_(4)exhibit a linear relationship with the catalytic activity of UiO-66-NH_(2)for DSOM reaction.展开更多
Hydroxyl radical(·OH)formation from Fe(Ⅱ)-bearing clay mineral oxygenation in the shallow subsurface has been well documented under moderate environmental conditions.However,the impact of freezing processes on t...Hydroxyl radical(·OH)formation from Fe(Ⅱ)-bearing clay mineral oxygenation in the shallow subsurface has been well documented under moderate environmental conditions.However,the impact of freezing processes on the·OH production capability of Fe(Ⅱ)-bearing clay minerals for organic contaminant degradation,particularly in seasonally frozen soils,remains unclear.In this study,we investigated the influence of pre-freezing durations on the mineral proprieties,·OH production,and phenol degradation during the oxygenation of reduced Fe-rich nontronite(rNAu-2)and Fe-poor montmorillonite(rSWy-3).During the freezing process of reduced clay minerals(1 mM Fe(Ⅱ)),the content of edge surface Fe and Fe(Ⅱ)decreased by up to 46%and 58%,respectively,followed by a slight increased as clay mineral particles aggregated and subsequently partially disaggregated.As the edge surface Fe(Ⅱ)is effective in O_(2) activation but less effective in the transformation of H_(2)O_(2) to·OH,the redistribution of edge surface Fe(Ⅱ)leads to that·OH production and phenol degradation increased initially and then decreased with pre-freezing durations ranging from 0 to 20 days.Moreover,the rate constants of phenol degradation for both the rapid and slow reaction phases also first increase and then decrease with freezing time.However,pre-freezing significantly influenced the rapid phase of phenol degradation by rNAu-2 but affected the slow phase by rSWy-3 due to the much higher edge-surface Fe(Ⅱ)content in rNAu-2.Overall,these findings provide novel insights into the mechanism of·OH production and contaminant degradation during the freeze-thaw processes in clay-rich soils.展开更多
Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane c...Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane conversion of 11%.Even at high conversion level of 63%,the selectivity of ethylene retained at 80%,which is competitive with the energy-demanding industrialized steam cracking route.A long-term test for 200 h resulted in stable conversion and product selectivity,showing the excellent catalytic stability.Both experimental and computational studies have identified that the hydrogen abstraction of B-OH groups by molecular oxygen dynamically generated the active sites and triggered ethane dehydrogenation.展开更多
Protoplasts prepared from tobacco (Nicotiana tabacum L., cultivar BY-2) suspension cells have similar morphological characteristics to those in animal cells. The hallmarks of apoptosis such as condensation and periphe...Protoplasts prepared from tobacco (Nicotiana tabacum L., cultivar BY-2) suspension cells have similar morphological characteristics to those in animal cells. The hallmarks of apoptosis such as condensation and peripheral distribution of nuclei, TUNEL positive reaction, and DNA ladders were observed when tobacco protoplasts were treated with the hydroxyl radical generating system (1.0 mmol/L FeSO4/0.5 mmol/L H2O2). In animals, the loss of transmembrane potential (DeltaPsi(m)) and the exposure of phospholipid phosphatidylserine (PS) are believed to be the main apoptosis events. To test whether these significant processes take place in plants, flow cytometry was used to detect annexin V binding and changes in DeltaPsi(m). Results showed that the PS turned out from inner membrane and DeltaPsi(m) gradually decreased during the apoptosis. All these apoptotic characteristics proved that hydroxyl radicals can cause typical programmed cell death (PCD) in tobacco protoplasts and this design can be served as an effective experiment system to explore the mechanism of plant apoptosis.展开更多
In the course of the basic research on the ammonia-evaporation reaction of manganese monoxide （MnO）, hydroxyl manganese chloride （Mn2（OH）3Cl） was found. The solubility and phase diagrams of the hydroxyl manganes...In the course of the basic research on the ammonia-evaporation reaction of manganese monoxide （MnO）, hydroxyl manganese chloride （Mn2（OH）3Cl） was found. The solubility and phase diagrams of the hydroxyl manganese chloride were investigated. The aqueous thermostat and vibrating bed were used to determine the solubility of hydroxyl manganese chloride in water, ammonium chloride and manganese chloride system, and the phase diagrams of multicomponent system were drawn. The research results indicate that hydroxyl manganese chloride has been produced in laboratory and is in favor of the solid-liquid separation at high temperature.展开更多
The hydroxyl radical（-OH）-scavenging ability of culture filtrates from submerged culture of Lentinula edodes AX3 and five mildews on lignocellulose substance was analysed. Only L. edodes AX3 showed significant -OH-s...The hydroxyl radical（-OH）-scavenging ability of culture filtrates from submerged culture of Lentinula edodes AX3 and five mildews on lignocellulose substance was analysed. Only L. edodes AX3 showed significant -OH-scavenging ability which reached 52.2% at about the 48th hour. All mildews could hardly scavenge -OH under the experimental conditions. -OH-scavenging ability is considered related to the mode and ability of lignocellulose degradation of a strain. The degradation or bioconversion products might be the substance base for.this effect.展开更多
S─mephenytoin and debrisoquin hydroxylation abilities were investigated in 118 normal Chinese Zhuang minority volunteers after co─administration po 100 mg racemic mephenytoin(MP)and 10 mg debrisoquin (DB). The rat...S─mephenytoin and debrisoquin hydroxylation abilities were investigated in 118 normal Chinese Zhuang minority volunteers after co─administration po 100 mg racemic mephenytoin(MP)and 10 mg debrisoquin (DB). The ratio between S─and R─enantiomers of mephenytoin in urinewas determined by implication of GC─NPD and used as the measure of the drug hydroxylation. 2 ofthe 118 subjects had S/R ratios greater than 1.0 and were poor hydroxylators of S─mephenytoin. The frequency of S─mephenytoin poor metabolizers (PM) was 10.2%. No PM of debrisoquin was found in the volunteers. It indicated that there was no relationship between S─mephenytoin P(4′)─ hydroxylation and debrisoquin 4─hydroxylation polymorphisms in Chinese Zhuang Minority population. In addition, 16 of the 118 volunteers(4 PMs and 12 EMs of S-mephenytoin) were se─lected to conduct the elimination kinetic studies of racemic mephenytoin and debrisoquin in urine. The pharmacokinetic parameters of S─, R─mephenytoin, DB and 4─OH─DB were calculated.展开更多
Hydroxylation of 3-nitrotyrosine （3-NT） and 3-NT containing peptide Gly-nitroTyr-Gly in aqueous solution by hydroxyl radical were investigated with gamma irradiation. The structures of the hydroxylated products were...Hydroxylation of 3-nitrotyrosine （3-NT） and 3-NT containing peptide Gly-nitroTyr-Gly in aqueous solution by hydroxyl radical were investigated with gamma irradiation. The structures of the hydroxylated products were confirmed by electrospray ionization mass spectrometry and ^1H NMR spectrometry. The reactivity of 3-nitrotyrosine has been investigated using density functional theory （DFT） calculation.展开更多
Mid-infrared absorption and Raman spectra of the geometrically frustrated material series, hydroxyl cobalt halides β-CO2（OH）3Cl and β-CO2（OH）3Br, are first, to the best of our knowledge, measured at room tempera...Mid-infrared absorption and Raman spectra of the geometrically frustrated material series, hydroxyl cobalt halides β-CO2（OH）3Cl and β-CO2（OH）3Br, are first, to the best of our knowledge, measured at room temperature, to study the corresponding relationship between their vibrational spectral properties and crystal microstructures. Through the comparative analysis of the four spectra we have categorically assigned the OH-related vibration modes of hydroxyl groups in the trimeric hydrogen bond environment （Co3 =OH）3 … Cl/Br, and tentatively suggested vibration modes of O-Co-O, Co O and Cl/Br-Co-Cl/Br units. These results can also become the basis for analysing their low-temperature spectral properties, which can help to understand the underlying physics of their exotic geometric frustration phenomena around phase transition temperatures.展开更多
The hydroxyl radical （·OH） plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric ·OH is very difficult because of its high reactivity and low atmospher...The hydroxyl radical （·OH） plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric ·OH is very difficult because of its high reactivity and low atmospheric abundance. In this article, a simple and highly sensitive method, high performance liquid chromatography coupled with coulometric detection （HPLC-CD）, was developed to determine ·OH indirectly by determining its reaction products with salicylic acid （SAL）, 2,3-dihydroxybenzoic acid （2,3-DHBA）, and 2,5-dihydroxybenzoic acid （2,5-DHBA）. Under the optimum conditions for its determination, 2,3-DHBA and 2,5-DHBA could be well separated and the detection limits for 2,3-DHBA were 3 ×10^-10 mol/L and for 2,5-DHBA were 1.5 ×10^-10 mol/L, which were lower than most previous reports. This method was also applied to measure atmospheric hydroxyl radical levels and demonstrated the feasibility in clean and polluted air.展开更多
Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts ...Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.展开更多
Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and effect of hydroxyl radicals on the interface between DSA anode and water was investigated by ...Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and effect of hydroxyl radicals on the interface between DSA anode and water was investigated by examining the quenching effect of iso-propanol on Orange II decolorization. We observed that with an increase in electrode potential from 4 to 12 V across electrodes at pH 7.0, the contribution percentage of hydroxyl radicals increased dramatically. More OH radicals were produced in acidic and alkaline conditions than at neutral conditions. At electrode potential of 4 V, the contribution percentage of hydroxyl radicals was obviously higher at near neutral pH conditions, while removal efficiency of Orange/I achieved was the lowest concurrently. Finally, for photocatalytic oxidation, electrochemical oxidation, and photoelectrochemical oxidation using the same DSA electrode, the effect of hydroxyl radicals proved to be dominant in photocatalytic oxidation but the contribution of hydroxyl radicals was not dominant in electrochemical oxidation, which implies the necessity of UV irradiation for electrochemical oxidation during water treatment.展开更多
Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to...Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst con- centration, were changed to obtain an optimal reaction conditions. H3＋nPMo12-nVnO40（n=1-3） are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.展开更多
Rare earth（Y, La and Nd） doped TiO2 thin films were prepared on glass slides by sol-gel method. The photocatalytic decomposition of methylene blue in aqueous solution was used as a probe reaction to evaluate their p...Rare earth（Y, La and Nd） doped TiO2 thin films were prepared on glass slides by sol-gel method. The photocatalytic decomposition of methylene blue in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of hydroxyl groups on hydrophilic and photocatalytic activities were investigated by means of techniques such as X-ray diffraction（XRD）, atomic force microscopy（AFM）, Fourier transform infrared（FTIR）, optical contact angle, UV-Visible spectroscopy and VIS spectroscopy. The results showed that an appropriate doping of rare earth could cause the TiO2 lattice distortion, inhibited phase transition from anatase to rutile, accelerated surface hydroxylation and produced more hydroxyl groups, which resulted in a denser surface and smaller grains（40–60 nm）, and a significant improvement in the hydrophilicity and photoreactivity of TiO2 thin films. The optimal content of rare earth was between 0.1 wt.% and 0.3 wt.%. Moreover, the modification mechanism of rare earth doping was also discussed.展开更多
As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4...As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.展开更多
Amphiphilic hydroxyl functioned polyester（HFP） can be used as compatibilizers for blends of starch and resins.We developed a synthetic method for effective preparation of HFPs.Water was removed by high flow rate N_2...Amphiphilic hydroxyl functioned polyester（HFP） can be used as compatibilizers for blends of starch and resins.We developed a synthetic method for effective preparation of HFPs.Water was removed by high flow rate N_2 rather than high vacuum during polycondensation of sebacic acid with xylitol,sorbitol,or mannitol in the presence of dehydrative condensation catalyst and the product is with[η]of 27.2 mL/g,M_n of 1903,M_w of 167,693,T_g of -30.5℃,T_m of 44.0℃.Weight loss is 1.73%under 200℃. The integral distributions of molecular weight are 43.6 wt%and 63.8 wt%over 10,000 and 3000,respectively.The results indicated that higher molecular weight HFP was economically synthesized.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52170156,52250056,and 52293443)the Shenzhen Science and Technology Program(No.KQTD20190929172630447).
文摘Harnessing bacteria for superoxide production in bioremediation holds immense promise,yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide.This study delves into a cost-effective approach to amplify superoxide production using an Arthrobacter strain,a prevalent soil bacterial genus.Our research reveals that introducing a carbon source along with specific iron-binding ligands,including deferoxamine(DFO),diethylenetriamine pentaacetate(DTPA),citrate,and oxalate,robustly augments microbial superoxide generation.Moreover,our findings suggest that these iron-binding ligands play a pivotal role in converting superoxide into hydroxyl radicals by modulating the electron transfer rate between Fe(Ⅲ)/Fe(Ⅱ)and superoxide.Remarkably,among the tested ligands,only DTPA emerges as a potent promoter of this conversion process when complexed with Fe(Ⅲ).We identify an optimal Fe(Ⅲ)to DTPA ratio of approximately 1:1 for enhancing hydroxyl radical production within the Arthrobacter culture.This research underscores the efficacy of simultaneously introducing carbon sources and DTPA in facilitating superoxide production and its subsequent conversion to hydroxyl radicals,significantly elevating bioremediation performance.Furthermore,our study reveals that DTPA augments superoxide production in cultures of diverse soils,with various soil microorganisms beyond Arthrobacter identified as contributors to superoxide generation.This emphasizes the universal applicability of DTPA across multiple bacterial genera.In conclusion,our study introduces a promising methodology for enhancing microbial superoxide production and its conversion into hydroxyl radicals.These findings hold substantial implications for the deployment of microbial reactive oxygen species in bioremediation,offering innovative solutions for addressing environmental contamination challenges.
文摘P450 enzymes-catalyzed aromatic hydroxylation plays an important role in detoxification,biosynthesis,and potential carcinogenic effect of aromatic compounds.Though it has been explored for decades,the actual process of aromatic hydroxylation and mechanism of regioselectivity catalyzed by cytochrome P450 monooxygenases remained ambiguous.Here,we have resolved these issues.With a stable chiral organofluorine probe,and especially with X-ray data of two isolated arene oxides derivatives,we demonstrate that an arene oxide pathway is definitely involved in P450-catalyzed aromatic hydroxylation.By the capture,isolation,identification and reactivity exploration of the arene 1,2-oxide and arene 2,3-oxide intermediates,together with advanced QM calculations,the mechanism of how two intermediates go to the same product has been elucidated.In addition to the model substrate,we also confirmed that an arene oxide intermediate is involved in the P450-catalyzed hydroxylation pathway of a natural product derivative methyl cinnamate,which indicates that this intermediate appears to be universal in P450-catalyzed aromatic hydroxylation.Our work not only provides the most direct evidence for the arene oxide pathway and new insights into the regioselectivity involved in P450-catalyzed aromatic hydroxylation,but also supplies a new synthetic approach to achieve the dearomatization of aromatic compounds.
基金the financial support from the National Natural Science Foundation of China(No.22178181)the Fundamental Research Funds for the Central Universities(Nankai University(No.63253204))。
文摘Achieving sustainable energy and chemical production has become an important issue for human society.Photocatalysis has attracted much attention due to its ability to harness solar energy to drive chemical reactions.Metal sulfide-based photocatalysts(e.g.,Cd S,Zn In2S4)have shown substantial potential in biomass-based hydroxyl compound valorization.In this review,we summarize the recent progress in metal sulfide-based photocatalysts for the photo upgrading of biomass-derived hydroxyl compounds coupled with reduction reactions(e.g.,CO_(2)reduction,H_(2)O_(2)generation,and H_(2)evolution).The mechanism of biomass redox reactions is discussed,highlighting the potential of realizing the valorization of biomass-derived compounds coupled with the reduction reactions,which is beneficial for researchers to actively explore biomass biorefinery pathways in order to modulate the selectivity of the valueadded products.Various modification strategies are presented,including elemental doping,defect engineering,heterojunction construction,and cocatalyst loading.These strategies modulate the energy band structure,surface electron density,and built-in electric field strength of metal sulfide-based photocatalysts,thereby enhancing their photocatalytic performance.The challenges and prospects of metal sulfidebased photocatalysts in biomass valorization are analyzed.This approach contributes to the development of photocatalysts that can accelerate biomass photo-upgrading coupling reactions.This review aims to provide deeper insights into the photocatalytic biorefinery pathways and contribute to the development of functionalized photocatalysts that can accelerate biomass photo upgrading,highlighting the synergistic effects of multiple coupling reactions.
基金supported by the National Natural Science Foundation of China(Nos.52301279 and 51901115)the Shandong Provincial Natural Science Foundation,China(ZR2023MB122 and ZR2019PEM001)+1 种基金the Outstanding Youth Innovation Team of Universities in Shandong Province(2024KJH067)the Innovation fund project for graduate student of China University of Petroleum(East China)supported by the Fundamental Research Funds for the Central Universities(No.23CX04010A)。
文摘Addressing inadequate OH^(*)adsorption in Ru Co alloy catalysts is crucial for boosting intermediate coverage and redirecting the water-splitting pathway.Herein,the adaptive P sites were strategically incorporated to overcome the aforementioned challenge.The P sites,as potent OH^(*)adsorption centers,synergize with Co sites to promote water dissociation and enrich surrounding Ru sites with H*intermediates,thus triggering the Volmer-Tafel route for hydrogen evolution reaction(HER).Besides,during the oxygen evolution reaction(OER),the surface of P-Ru Co was reconstructed into Ru-doped Co OOH with anchored PO_(4)^(3-).These PO_(4)^(3-)not only circumvent the intrinsic OH^(*)adsorption limitations of Ru-Co OOH in the adsorbate evolution mechanism(AEM)by rerouting to a more expeditious lattice oxygen oxidation mechanism(LOM)but also improve the coverage of key oxygen-containing intermediates,significantly accelerating OER kinetics.Consequently,the P-Ru Co demonstrates exceptional bifunctional performance,with overpotentials of 29 m V for HER and 222 m V for OER at 10 m A cm^(-2).Remarkably,the mass activities of PRu Co for HER(5.48 A mg^(-1))and OER(2.13 A mg^(-1))are 6.2 and 11.2 times higher than those of its commercial counterparts(Ru/C for HER and RuO_(2)for OER),respectively.When integrated into an anionexchange-membrane electrolyzer,this catalyst achieves ampere-level current densities of 1.32 A cm^(-2)for water electrolysis and 1.23 A cm^(-2)for seawater electrolysis at 2.1 V,with a 500-h durability.
基金the financial support from National Natural Science Foundation of China(22363001,22378379,22479032,22022814)the National Key R&D Project(2022YFA1503900)+6 种基金the Natural Science Special Foundation of Guizhou University(No.202140)National Natural Science Foundation of China for Single-Atom Catalysis(22388102)the Youth Innovation Promotion Association CAS(Y2021057)Dalian Science Foundation for Distinguished Young Scholars(2021RJ10)Grant.YLU-DNL Fund(2022010)the Young Top-notch Talents of Liaoning Province(XLYC2203140)the Liaoning Foundation for Distinguished Young Scholars(2025JH6/101100011).
文摘UiO-66-H MOFs can effectively catalyze the direct selective oxidation of methane(DSOM)to high value-added oxygenates under mild conditions.However,UiO-66-NH_(2)with benzene-1,4-dicarboxylate(NH_(2)-BDC)ligand modifying the Zr-oxo nodes exhibits relatively inferior catalytic performance for DSOM.Here,a combination of density functional theory(DFT)calculations and experiments was employed to explore the underlying reasons for the limited catalytic activity of UiO-66-NH_(2).The results indicate that the methane hydroxylation performance of UiO-66-NH_(2)is almost unaffected by the increase of·OH concentration.This is attributed to the formation of substantial non-covalent hydrogen bonds between the oxygen atoms of oxygenic species on the Zr-oxo nodes and the hydrogen atoms of-NH_(2)groups,which diminishes the spin density distribution on the active sites of(·OH)m/UiO-66-NH_(2),leading to minimal change of the adsorption energy of CH_(4).Additionally,the calculated adsorption energies(Eads)of CH_(4)exhibit a linear relationship with the catalytic activity of UiO-66-NH_(2)for DSOM reaction.
基金supported by the National Natural Science Foundation of China(Nos.U22A20591,42077185,42107217)the Sichuan Province Science and Technology Program for Distinguished Young Scholars(No.2022JDJQ0010)+1 种基金the Sichuan Science and Technology Program(No.2024NSFSC0842)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(No.SKLGP2020Z002)。
文摘Hydroxyl radical(·OH)formation from Fe(Ⅱ)-bearing clay mineral oxygenation in the shallow subsurface has been well documented under moderate environmental conditions.However,the impact of freezing processes on the·OH production capability of Fe(Ⅱ)-bearing clay minerals for organic contaminant degradation,particularly in seasonally frozen soils,remains unclear.In this study,we investigated the influence of pre-freezing durations on the mineral proprieties,·OH production,and phenol degradation during the oxygenation of reduced Fe-rich nontronite(rNAu-2)and Fe-poor montmorillonite(rSWy-3).During the freezing process of reduced clay minerals(1 mM Fe(Ⅱ)),the content of edge surface Fe and Fe(Ⅱ)decreased by up to 46%and 58%,respectively,followed by a slight increased as clay mineral particles aggregated and subsequently partially disaggregated.As the edge surface Fe(Ⅱ)is effective in O_(2) activation but less effective in the transformation of H_(2)O_(2) to·OH,the redistribution of edge surface Fe(Ⅱ)leads to that·OH production and phenol degradation increased initially and then decreased with pre-freezing durations ranging from 0 to 20 days.Moreover,the rate constants of phenol degradation for both the rapid and slow reaction phases also first increase and then decrease with freezing time.However,pre-freezing significantly influenced the rapid phase of phenol degradation by rNAu-2 but affected the slow phase by rSWy-3 due to the much higher edge-surface Fe(Ⅱ)content in rNAu-2.Overall,these findings provide novel insights into the mechanism of·OH production and contaminant degradation during the freeze-thaw processes in clay-rich soils.
基金supported by the National Natural Science Foundation of China (21225312, U1462120, 21473206)Cheung Kong Scholars Programme of China (T2015036)~~
文摘Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane conversion of 11%.Even at high conversion level of 63%,the selectivity of ethylene retained at 80%,which is competitive with the energy-demanding industrialized steam cracking route.A long-term test for 200 h resulted in stable conversion and product selectivity,showing the excellent catalytic stability.Both experimental and computational studies have identified that the hydrogen abstraction of B-OH groups by molecular oxygen dynamically generated the active sites and triggered ethane dehydrogenation.
文摘Protoplasts prepared from tobacco (Nicotiana tabacum L., cultivar BY-2) suspension cells have similar morphological characteristics to those in animal cells. The hallmarks of apoptosis such as condensation and peripheral distribution of nuclei, TUNEL positive reaction, and DNA ladders were observed when tobacco protoplasts were treated with the hydroxyl radical generating system (1.0 mmol/L FeSO4/0.5 mmol/L H2O2). In animals, the loss of transmembrane potential (DeltaPsi(m)) and the exposure of phospholipid phosphatidylserine (PS) are believed to be the main apoptosis events. To test whether these significant processes take place in plants, flow cytometry was used to detect annexin V binding and changes in DeltaPsi(m). Results showed that the PS turned out from inner membrane and DeltaPsi(m) gradually decreased during the apoptosis. All these apoptotic characteristics proved that hydroxyl radicals can cause typical programmed cell death (PCD) in tobacco protoplasts and this design can be served as an effective experiment system to explore the mechanism of plant apoptosis.
基金Project (062702) supported by Innovation Funds of Institute of Process Engineering,Chinese Academy of Sciences
文摘In the course of the basic research on the ammonia-evaporation reaction of manganese monoxide （MnO）, hydroxyl manganese chloride （Mn2（OH）3Cl） was found. The solubility and phase diagrams of the hydroxyl manganese chloride were investigated. The aqueous thermostat and vibrating bed were used to determine the solubility of hydroxyl manganese chloride in water, ammonium chloride and manganese chloride system, and the phase diagrams of multicomponent system were drawn. The research results indicate that hydroxyl manganese chloride has been produced in laboratory and is in favor of the solid-liquid separation at high temperature.
文摘The hydroxyl radical（-OH）-scavenging ability of culture filtrates from submerged culture of Lentinula edodes AX3 and five mildews on lignocellulose substance was analysed. Only L. edodes AX3 showed significant -OH-scavenging ability which reached 52.2% at about the 48th hour. All mildews could hardly scavenge -OH under the experimental conditions. -OH-scavenging ability is considered related to the mode and ability of lignocellulose degradation of a strain. The degradation or bioconversion products might be the substance base for.this effect.
文摘S─mephenytoin and debrisoquin hydroxylation abilities were investigated in 118 normal Chinese Zhuang minority volunteers after co─administration po 100 mg racemic mephenytoin(MP)and 10 mg debrisoquin (DB). The ratio between S─and R─enantiomers of mephenytoin in urinewas determined by implication of GC─NPD and used as the measure of the drug hydroxylation. 2 ofthe 118 subjects had S/R ratios greater than 1.0 and were poor hydroxylators of S─mephenytoin. The frequency of S─mephenytoin poor metabolizers (PM) was 10.2%. No PM of debrisoquin was found in the volunteers. It indicated that there was no relationship between S─mephenytoin P(4′)─ hydroxylation and debrisoquin 4─hydroxylation polymorphisms in Chinese Zhuang Minority population. In addition, 16 of the 118 volunteers(4 PMs and 12 EMs of S-mephenytoin) were se─lected to conduct the elimination kinetic studies of racemic mephenytoin and debrisoquin in urine. The pharmacokinetic parameters of S─, R─mephenytoin, DB and 4─OH─DB were calculated.
基金The authors would like to thank the financial support from the National Natural Science Foundation of China （No. 20320130046） ；the Specialized Research Fund for the Doctoral Program of Higher Education （SRFDP） of M0E （No. 20030003049）.
文摘Hydroxylation of 3-nitrotyrosine （3-NT） and 3-NT containing peptide Gly-nitroTyr-Gly in aqueous solution by hydroxyl radical were investigated with gamma irradiation. The structures of the hydroxylated products were confirmed by electrospray ionization mass spectrometry and ^1H NMR spectrometry. The reactivity of 3-nitrotyrosine has been investigated using density functional theory （DFT） calculation.
基金Project supported by the Grant-in-Aid for Scientific Research from the Japanese Society for the Promotion of Science (Grant No.Kiban-B 19340100)the Grant-in-Aid for Scientific Research on Priority Areas from the Ministry of Education,Culture,Sports,Science and Technology,Japan (Grant No.Tokutei 22014008)
文摘Mid-infrared absorption and Raman spectra of the geometrically frustrated material series, hydroxyl cobalt halides β-CO2（OH）3Cl and β-CO2（OH）3Br, are first, to the best of our knowledge, measured at room temperature, to study the corresponding relationship between their vibrational spectral properties and crystal microstructures. Through the comparative analysis of the four spectra we have categorically assigned the OH-related vibration modes of hydroxyl groups in the trimeric hydrogen bond environment （Co3 =OH）3 … Cl/Br, and tentatively suggested vibration modes of O-Co-O, Co O and Cl/Br-Co-Cl/Br units. These results can also become the basis for analysing their low-temperature spectral properties, which can help to understand the underlying physics of their exotic geometric frustration phenomena around phase transition temperatures.
基金This work was supported by the National Natural Science Foundation of China(No.40075026).
文摘The hydroxyl radical （·OH） plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric ·OH is very difficult because of its high reactivity and low atmospheric abundance. In this article, a simple and highly sensitive method, high performance liquid chromatography coupled with coulometric detection （HPLC-CD）, was developed to determine ·OH indirectly by determining its reaction products with salicylic acid （SAL）, 2,3-dihydroxybenzoic acid （2,3-DHBA）, and 2,5-dihydroxybenzoic acid （2,5-DHBA）. Under the optimum conditions for its determination, 2,3-DHBA and 2,5-DHBA could be well separated and the detection limits for 2,3-DHBA were 3 ×10^-10 mol/L and for 2,5-DHBA were 1.5 ×10^-10 mol/L, which were lower than most previous reports. This method was also applied to measure atmospheric hydroxyl radical levels and demonstrated the feasibility in clean and polluted air.
基金Project supported by the National Natural Science Foundation of China(Nos.49971046 and 49831005).
文摘Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.
基金supported by the National Natural Science Foundation of China (No. 50708037)the Starting Fund for Talents of North China University of Water Conservancy and Electric Power
文摘Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and effect of hydroxyl radicals on the interface between DSA anode and water was investigated by examining the quenching effect of iso-propanol on Orange II decolorization. We observed that with an increase in electrode potential from 4 to 12 V across electrodes at pH 7.0, the contribution percentage of hydroxyl radicals increased dramatically. More OH radicals were produced in acidic and alkaline conditions than at neutral conditions. At electrode potential of 4 V, the contribution percentage of hydroxyl radicals was obviously higher at near neutral pH conditions, while removal efficiency of Orange/I achieved was the lowest concurrently. Finally, for photocatalytic oxidation, electrochemical oxidation, and photoelectrochemical oxidation using the same DSA electrode, the effect of hydroxyl radicals proved to be dominant in photocatalytic oxidation but the contribution of hydroxyl radicals was not dominant in electrochemical oxidation, which implies the necessity of UV irradiation for electrochemical oxidation during water treatment.
基金Supported by the National Natural Science Foundation of China （Nos.20306011, 20476046） and the Ph.D. Program Foundation for Chinese Universities （No.20040291002）.
文摘Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst con- centration, were changed to obtain an optimal reaction conditions. H3＋nPMo12-nVnO40（n=1-3） are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.
基金Project supported by the National Natural Science Foundation of China(51162022,21201098)Jiangxi Provincial Education Department(GJJ14126)
文摘Rare earth（Y, La and Nd） doped TiO2 thin films were prepared on glass slides by sol-gel method. The photocatalytic decomposition of methylene blue in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of hydroxyl groups on hydrophilic and photocatalytic activities were investigated by means of techniques such as X-ray diffraction（XRD）, atomic force microscopy（AFM）, Fourier transform infrared（FTIR）, optical contact angle, UV-Visible spectroscopy and VIS spectroscopy. The results showed that an appropriate doping of rare earth could cause the TiO2 lattice distortion, inhibited phase transition from anatase to rutile, accelerated surface hydroxylation and produced more hydroxyl groups, which resulted in a denser surface and smaller grains（40–60 nm）, and a significant improvement in the hydrophilicity and photoreactivity of TiO2 thin films. The optimal content of rare earth was between 0.1 wt.% and 0.3 wt.%. Moreover, the modification mechanism of rare earth doping was also discussed.
文摘As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.
基金the financial support of National Key Technology R&D Program(No.2006BAD07A06)National"863"Program Project of China(No.2006AA100216)
文摘Amphiphilic hydroxyl functioned polyester（HFP） can be used as compatibilizers for blends of starch and resins.We developed a synthetic method for effective preparation of HFPs.Water was removed by high flow rate N_2 rather than high vacuum during polycondensation of sebacic acid with xylitol,sorbitol,or mannitol in the presence of dehydrative condensation catalyst and the product is with[η]of 27.2 mL/g,M_n of 1903,M_w of 167,693,T_g of -30.5℃,T_m of 44.0℃.Weight loss is 1.73%under 200℃. The integral distributions of molecular weight are 43.6 wt%and 63.8 wt%over 10,000 and 3000,respectively.The results indicated that higher molecular weight HFP was economically synthesized.
