Annual haze in Northern Thailand has become increasingly severe,impacting health and the environment.How-ever,the sources of the haze remain poorly quantified due to limited observational data on aerosol molecular tra...Annual haze in Northern Thailand has become increasingly severe,impacting health and the environment.How-ever,the sources of the haze remain poorly quantified due to limited observational data on aerosol molecular tracers.This study comprehensively investigates chemical composition of PM_(2.5),including both inorganic and organic compounds throughout haze and post-haze periods in 2019 at a rural site of Northern Thailand.Average PM_(2.5) concentrations during haze and post-haze period were 87±36 and 21±11μg/m^(3),respectively.Organic matter was the dominant contributor in PM_(2.5) mass,followed by water soluble inorganic ions and mineral dust.Molecular markers,including levoglucosan,dehydroabietic acid,and 4-nitrocatechol,and ions(Cl^(-),and K^(+)),were used to characterize low haze(PM_(2.5)<100μg/m^(3))and episodic haze(PM_(2.5)>100μg/m^(3)).Low haze is associated with local aerosols from agricultural waste burning,while episodic haze is linked to aged aerosols from mixed agricultural waste,softwood,and hardwood burning.Source apportionment incorporating these molecular markers in receptor modelling(Positive matrix factorization),identified three distinct biomass burning sources:mixed,local,and aged biomass burnings,contributing 31,19 and 13%of PM_(2.5) during haze period.During post-haze period,contributions shifted,with local biomass burning(32%)comparable to secondary sulfate(34%)and mixed dust and traffic sources(26%).These findings demonstrate that both regional and local sources con-tribute to severe haze,highlighting the need for integrated policies for cross-border cooperation as well as stricter regulations to reduce biomass burning in Northern Thailand and Southeast Asia.展开更多
Although supported solid amine adsorbents have attracted great attention for CO_(2) capture,critical chemical deactivation problems including oxidative degradation and urea formation have severely restricted their pra...Although supported solid amine adsorbents have attracted great attention for CO_(2) capture,critical chemical deactivation problems including oxidative degradation and urea formation have severely restricted their practical applications for flue gas CO_(2) capture.In this work,we reveal that the nature of surface hydroxyl groups(metal hydroxyl Al–OH and nonmetal hydroxyl Si–OH)plays a key role in the deactivation mechanisms.The polyethyleneimine(PEI)supported on Al–OH-containing substrates suffers from severe oxidative degradation during the CO_(2) capture step due to the breakage of amine-support hydrogen bonding networks,but exhibits an excellent anti-urea formation feature by preventing dehydration of carbamate products under a pure CO_(2) regeneration atmosphere.In contrast,PEI supported on Si–OHcontaining substrates exhibits excellent anti-oxidative stability under simulated flue gas conditions by forming a robust hydrogen bonding protective network with Si–OH,but suffers from obvious urea formation during the pure CO_(2) regeneration step.We also reveal that the urea formation problem for PEI-SBA-15 can be avoided by the incorporation of an OH-containing PEG additive.Based on the intrinsic understanding of degradation mechanisms,we successfully synthesized an adsorbent 40PEI-20PEG-SBA-15 that demonstrates outstanding stability and retention of a high CO_(2) capacity of 2.45 mmol g^(−1) over 1000 adsorption–desorption cycles,together with negligible capacity loss during aging in simulated flue gas(10%CO_(2)+5%O_(2)+3%H_(2)O)for one month at 60–70℃.We believe this work makes great contribution to the advancement in the field of ultra-stable solid amine-based CO_(2) capture materials.展开更多
Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM...Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM60B magnesium alloy in order to provide sufficient protection against the corrosion.The first composite(Ti-Zr/hybrid)was obtained via combination o f a hybrid sol-gel film(synthesized by mixing tetraethoxysilane(TEOS),and 3-glycidyloxypropyl-trimethoxysilane(GPTMS))as outer layer and Ti-Zr conversion coating as primer.Also,the second composite(Ti-Zr/PTMS)was applied in a similar manner by combination o f phenyl-trimethoxysilane(PTMS)so lgel film with the Ti-Zr conversion coating.The morphology and elemental composition of the Ti-Zr conversion film were assessed by the Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS),respectively.A cracky conversion film was applied on the alloy surface after immersion in the Ti-Zr conversion coating bath which was mainly composed of MgO,T i02,Zr02,and MgF2 compounds.Uniform,but not-adherent PTMS and hybrid sol-gel films(pure sol-gel films)with obvious defects were directly deposited onto the magnesium alloy without the Ti-Zr pretreatment which were morphologically characterized by the SEM.However,formation o f relatively uniform and completely defect-free Ti-Zr/hybrid and Ti-Zr/PTMS composites after using the Ti-Zr conversion coating as pretreatment was revealed by the SEM observations.In addition,the defects of the Ti-Zr conversion coating were completely filled by the sol-gel layers.The Ti-Zr/PTMS and Ti-Zr/hybrid composite coatings were provided much better corrosion protection capacity than the pure PTMS and hybrid sol-gel films,respectively which was confirmed by the Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)examinations in 0.05 M NaCl solution.展开更多
Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectr...Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.展开更多
This work reports synthesis and characterization of heterocyclic functionalized polymers, poly（triazole-etherimidazole）s（PTAEI）, from a dialkyne-terminated compound, 3-（4,5-bis（4-（propargyloxy）phenyl）-1H-imid...This work reports synthesis and characterization of heterocyclic functionalized polymers, poly（triazole-etherimidazole）s（PTAEI）, from a dialkyne-terminated compound, 3-（4,5-bis（4-（propargyloxy）phenyl）-1H-imidazol-2-yl）-9-ethyl-9H-carbazole, by using click reaction. PTAEIs were characterized and their properties such as solubility, thermal, mechanical, photophysical and metal ions adsorption were investigated. These polymers had weight average molar masses（Mw） in the range of 19100-26700 g/mol, exhibited excellent solubility in polar aprotic solvents and formed low-colored flexible thin films by solution casting method. They exhibited good thermal stability with glass transition temperatures（Tg） between 160 °C and 211 °C and 10% weight loss temperatures（T10%） in the range of 308-426 °C. Nanocomposites of PTAEIs with epoxide-terminated Fe3O4 showed that strong interfacial interaction between inorganic particles and the polymer matrix contributed to the enhanced thermal and mechanical properties. The photoluminescence intensity of the PTAEIs increased and the spectra red shifted with increasing Fe3O4 content. The PTAEIs and nanocomposites were tested for their extraction capability of metal ions from aqueous solutions either individually or in the mixture.展开更多
A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The ...A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The electrochemical behavior of captopril (CAP) at the surface of the modified electrode was investigated using electroanalytical methods. The modified electrode showed excellent electrocatalytic activity for the oxidation of CAP in aqueous solutions at physiological pH values. Cyclic voltammetric curves showed that the oxidation of CAP at the surface of the modified electrode reduced its overpotential by more than 290 mV. The modified electrode was used for detecting captopril using cyclic voltammetry and square wave voltammetry techniques. A calibration curve in the range of 0.03 to 2400 μmol/L was obtained that had a detection limit of 0.0096 μmol/L (3?) under the optimized conditions. The modified electrode was successfully used for the determination of captopril in pharmaceutical and biological samples.展开更多
The inhibition effect of electrochemical noise, EIS and surface analysis to evaluate N'-bis (2-pyridylmethylidene)- 1,2-diiminoethane (BPIE) Schiff base against AZ91D alloy corrosion in 0.01 mol/L HCl was investig...The inhibition effect of electrochemical noise, EIS and surface analysis to evaluate N'-bis (2-pyridylmethylidene)- 1,2-diiminoethane (BPIE) Schiff base against AZ91D alloy corrosion in 0.01 mol/L HCl was investigated by different electrochemical methods. Potentiodynamic polarization curves revealed that the BPIE acts as a mixed-type corrosion inhibitor. Electrochemical impedance spectroscopy (EIS) measurements confirmed the corrosion inhibition effect of the BPIE. As the inhibitor concentration increased, the charge transfer resistance increased and the double layer capacitance decreased due to more inhibitor adsorption on the surface. The results obtained by analysis of electrochemical noise (EN) data in time and frequency domains are in good agreement with EIS and polarization results. Moreover, scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) were used to investigate the corrosion inhibition of the BPIE. SEM images showed that the corrosion damage of the alloy surface reduced in the presence of BPIE. The intensity of the XRD peaks corresponding to magnesium-rich α phase increased in the presence of BPIE, indicating lower corrosion of alloy sample. Also, EDX analysis approved the corrosion inhibition performance of the BPIE. The studied Schiff base compound acts by physical adsorption on the alloy surface and its adsorption obeys the Langmuir isotherm.展开更多
Carbon dioxide(CO_(2))capture using magnesium oxide(MgO)-based adsorbents at intermediate temperatures has been regarded as a very prospective technology for their relatively high adsorption capacity,low cost,and wide...Carbon dioxide(CO_(2))capture using magnesium oxide(MgO)-based adsorbents at intermediate temperatures has been regarded as a very prospective technology for their relatively high adsorption capacity,low cost,and wide availability.During the past few years,great effort has been devoted to the fabrication of molten salts-modified MgO-based adsorbents.The extraordinary progress achieved by coating with molten salts greatly promotes the COcapture capacity of MgO-based adsorbents.Therefore,we feel it necessary to deliver a timely review on this type of COcapturing materials,which will benefit the researchers working in both academic and industrial areas.In this work,we classified the molten saltsmodified MgO adsorbents into four categories:(1)homogenous molten salt-modified MgO adsorbents,(2)molten salt-modified double salts-based MgO adsorbents,(3)mixed molten salts-modified MgO adsorbents,and(4)molten salts-modified MgO-based mixed oxides adsorbents.This contribution critically reviews the recent developments in the synthetic method,adsorption capacity,reaction kinetics,promotion mechanism,operational conditions and regenerability of the molten salts-modified MgO COadsorbents.The challenges and prospects in this promising field of molten salts-modified MgO COadsorbents in real applications are also briefly mentioned.展开更多
Objective: To evaluate the total phenolic content and compare the antioxidant activity of various solvent extracts and fractions from the aerial parts of Coronopus didymus through various assays. Methods: Total phenol...Objective: To evaluate the total phenolic content and compare the antioxidant activity of various solvent extracts and fractions from the aerial parts of Coronopus didymus through various assays. Methods: Total phenolic content was determined using the Folin-Ciocalteu assay and the in vitro antioxidant activity of a number of different extracts was investigated in a dose-dependent manner with three different methods: the 2,2-diphenyl-1-picrylhydrazyl(DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt(ABTS) and ferric reducing antioxidant power(FRAP) assays. A flavone was isolated from the most active ethanolic extract with high antioxidant activity using size exclusion chromatography. IC_(50) values were calculated for the DPPH and ABTS methods. The FRAP activity was assessed in terms of μM Fe(II) equivalent. Results: The phenolic content was found to be highest in the ethanol extract(CDA Et; 47.8 mM GAE) and the lowest in the dichloromethane extract(CDA DCM; 3.13 mM GAE). The ethanol extract showed high radical scavenging activity towards DPPH and ABTS radicals with IC_(50) values of(7.80 × 10~2) and(4.32 × 10~2) μg/m L, respectively. The most active ethanol extract had a FRAP value of 1 921.7 μM Fe(Ⅱ) equivalent. The isolated flavone F10C(5,7,4'-trihydroxy-3'-methoxy flavone) was far more effective for scavenging free radicals in the DPPH and ABTS assays with IC_(50) of 43.8 and 0.08 μg/m L, than the standard trolox, with IC_(50) values of 97.5 and 21.1 μg/m L, respectively. In addition, the flavone F10C and the standard ascorbic acid had FRAP values of 1 621.7 and 16 038.0 μM Fe(Ⅱ) equivalents, respectively. Conclusions: The total phenolic content of extracts in decreasing order is ethanol extract(CDA Et)> acetone extract(CDA ACE)> phenolic extract(CDA MW)> n-hexane extract(CDA nHX)> chloroform extract(CDA CHL)> dichloromethane extract(CDA DCM). The ordering of extracts in terms of antioxidant activity from highest to lowest is CDA Et> CDA MW> CDA DCM> CDA CHL> CDA ACE> CDA nHX in DPPH, ABTS and FRAP assays. A significant relationship is found between antioxidant potential and total phenolic content, suggesting that phenolic compounds are the major contributors to the antioxidant activity of Coronopus didymus.展开更多
A new solvothermal post-synthesis treatment for preparing high aspect ratio magnesium aluminium layered double hydroxides(Mg Al–LDHs) has been developed. Treating laurate-intercalated Mg Al–LDHs in pure ethanol in a...A new solvothermal post-synthesis treatment for preparing high aspect ratio magnesium aluminium layered double hydroxides(Mg Al–LDHs) has been developed. Treating laurate-intercalated Mg Al–LDHs in pure ethanol in an autoclave for 48 h at 150 °C was found to produce delaminated MgA l–LDH nanosheets with a thickness of ~2.6 nm and an aspect ratio of ~105. It is proposed that the high pressure solvothermal process promotes the insertion of ethanol molecules into the LDH interlayer space, thereby facilitating delamination. This new post-synthesis treatment provides the opportunity for a facile, large scale route to highly delaminated high aspect ratio LDHs, which might be of interest towards novel nanomaterials for energy conversion and storage.展开更多
A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine)(PMT)-modified glassy carbon electrode(GCE) to form a nano-Au/PMT composite-modified GCE(nano-Au/PMT/GCE)...A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine)(PMT)-modified glassy carbon electrode(GCE) to form a nano-Au/PMT composite-modified GCE(nano-Au/PMT/GCE).Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode.The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine(DA) and uric acid(UA) in phosphate buffer solution(pH = 7.00).Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0 ×10–8 to 10–6 mol/L for DA and 7.0 × 10–8 to 10–6 mol/L for UA.The detection limits were 3.7 × 10–8mol/L for DA and 4.5 × 10–8 mol/L for UA at a signal-to-noise ratio of 3.According to our experimental results,nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.展开更多
Objective:To synthesis 2-substituted-4,5-diphenyl-N- alkyl imidazole derivatives,and evaluate their antibacterial activity.Methods:A mixture of benzil（10 mmol） and ammonium acetate（0.1 mol）（immediately fused） in...Objective:To synthesis 2-substituted-4,5-diphenyl-N- alkyl imidazole derivatives,and evaluate their antibacterial activity.Methods:A mixture of benzil（10 mmol） and ammonium acetate（0.1 mol）（immediately fused） in glacial acetic acid（25 mL） was stirred at 80-100℃for 1 h under nitrogen atmosphere（to prevent incorporation of any atmospheric impurities and moisture）. Substituted aldehydes（10 mmol） in glacial acetic acid（5 mL） was added drop-wise over a period of 15-20 min at the same temperature and stirred for another 4 h,the progress of the reaction was monitored by TLC test using ethyl acetate as eluent.The newly synthesized compounds were characterized by IR,<sup>1</sup>HNMR,<sup>13</sup>CNMR and by mass spectroscopy.Results:All the synthesized compounds were confirmed by spectroscopical techniques and evaluated for antimicrobial activity against Staphylococcus aureus（S.aurius）,Bacilus subtilus（B.subtilus）,and Escheria coli （E.coli）.These compounds showed antibacterial activity（zone of inhibition） against S.aurius ranged from 3 mm to 9 mmin diameter,B.subtilus,4 -8 mm,and E.coli 5 -12 mm.Out of 2a-2e, only 2a and 2b showed some sort of activity but none of them had considerable activity compared with that of the standard.Conclusions:All the synthesized compounds show moderate activity against the tested bacteria S.aurius,B.subtilus,and E.coli.So,further structural modification is necessary to improve the antibacterial action of 2-substituted-4,5-diphenyl-N-alkyl imidazole derivatives.展开更多
Five new optically active polyamides （PAs） 6a-6e were prepared by direct polycondensation reaction of 2-（1,3- isoindolinedione-2-yl）-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-Se in a...Five new optically active polyamides （PAs） 6a-6e were prepared by direct polycondensation reaction of 2-（1,3- isoindolinedione-2-yl）-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-Se in a medium consisting of triphenyl phosphite （TPP）, calcium chloride, pyridine （Py） and N-methyl-2-pyrrolidone （NMP）. The polycondensation reaction produced a series of polyamids 6a-6e in quantitative yields with inherent viscosities of 0.26-0.39 dL/g. The resulting polymers were fully characterized by means of ^1H-NMR, FT-1R spectroscopy, elemental analysis, inherent viscosity and specific rotation. Thermal properties of these polymers were investigated using thermal gravimetric analysis （TGA） and differential thermal gravimetry （DTG）. Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethyl acetamide （DMAc）, N,N-dimethyl formamide （DMF）, dimethyl sulfoxide （DMSO）, N-methyl-2-pyrrolidone （NMP） and sulfuric acid.展开更多
Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, ro...Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, room temperature and surfactant free strategy which is able to form high surface area metal nanosponges with a three-dimensional（3D） porous structure. The structure of as-prepared nanosponges was characterized using the techniques of field emission scanning electron microscopy（FESEM）, energy dispersive spectroscopy（EDS） and cyclic voltammetry（CV）. Then, the electrocatalytic activities of Pd Ru NPNs towards formic acid oxidation were examined by electrochemical measurements including CV,chronoamperometry, and electrochemical impedance spectroscopy（EIS）. Based on studies, it was found that the current density of formic acid oxidation（FAO） is strongly dependent on the composition of Pd Ru NPNs. The best performance was realized for Pd;Ru;NPNs compared to monometallic Pd counterpart and other bimetallic NPNs which might be ascribed to the role of Ru in the decrease of CO adsorption strength on the catalyst and consequently the priority of formic acid oxidation through the direct pathway. The Pd;Ru;NPNs also showed the maximum current density and stability in chronoamperometric measurements. In addition, comparative studies were performed between as-prepared NPNs and CNTs-supported Pd nanoparticles（Pd NPs/CNTs）. The present results demonstrated the unique structural advantages of NPNs compared to individual Pd NPs supported on the CNT which leads to the promising performance of NPNs as supportless catalysts for the oxidation of formic acid.展开更多
Novel dopamine-derivative compound,3,5-diamino-N-（3,4-dihydroxyphenethyl）benzamide（3,5-DAB）was prepared in two steps.In the first step dopamine hydrochloride was reacted with 3,5-dinitrobenzoyl chloride in the pre...Novel dopamine-derivative compound,3,5-diamino-N-（3,4-dihydroxyphenethyl）benzamide（3,5-DAB）was prepared in two steps.In the first step dopamine hydrochloride was reacted with 3,5-dinitrobenzoyl chloride in the presence of propylene oxide.In the second step reduction of nitro groups resulted in preparation of 3,5-DAB in quantitative yield.This material was characterized using conventional spectroscopic methods such as FT-IR and ~1H NMR.In addition,the redox response of a modified carbon nanotubes paste electrode of 3,5-DAB was investigated in aqueous solution at a neutral pH.The result showed that the electrode process has a quasi-reversible response,withΔE_p,greater than the（59/n） mV expected for a reversible system.Finally,the diffusion coefficient for redox process in paraffin oil matrix obtained using chronoamperometry methods.展开更多
The effect of a salicylic Schiff base componnd （Salcn） on the corrosion of AZ91 alloy in 30% ethylene glycol aqueous solution （30% EG/W） was investigated by electrochemical methods. Scanning electron microscope wa...The effect of a salicylic Schiff base componnd （Salcn） on the corrosion of AZ91 alloy in 30% ethylene glycol aqueous solution （30% EG/W） was investigated by electrochemical methods. Scanning electron microscope was used to observe the alloy surface in corrosive solution before and after the addition of inhibitor. There was no significant corrosion inhibition at the room temperature but high inhibition efficiencies were obtained at elevated temperatures due to the formation of chemisorbed inhibitor monolayer. As the inhibitor concentration increased, the inhibition efficiency increased probably due to more inhibitor adsorption on the alloy surface.展开更多
A series of novel 5-benzylidene-3-（3-fluoro-4-yl-morpholin-4-yl-phenylimino）thiazolidin-4-one derivatives were synthesized using[bmIm]OH as a catalyst and were tested for their antibacterial and antifungal activitie...A series of novel 5-benzylidene-3-（3-fluoro-4-yl-morpholin-4-yl-phenylimino）thiazolidin-4-one derivatives were synthesized using[bmIm]OH as a catalyst and were tested for their antibacterial and antifungal activities.These compounds showed moderate in vitro activities against the microorganisms tested.展开更多
A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridi...A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridine （Py） and dimethylformamide （DMF） system as condensing agent. The resulting thermally stable poly（amide-imide）s were obtained in good to high yields and inherent viscosities ranging between 0.35 dL/g and 0.58 dL/g and were characterized with FTIR, IH-NMR, CHN, Ultraviolet, TGA and DTG techniques.展开更多
An efficient synthesis of tetrahydroquinoline derivatives is reported via three component coupling reactions of aldehydes and anilines with various dienophiles in the presence of a catalytic amount of perchloric acid ...An efficient synthesis of tetrahydroquinoline derivatives is reported via three component coupling reactions of aldehydes and anilines with various dienophiles in the presence of a catalytic amount of perchloric acid adsorbed on silica gel（HClO;-SiO;） under mild reaction conditions.展开更多
A high‐quality polycrystalline bismuth vanadate(BiVO4)film was prepared on a fluorine‐doped tinoxide substrate via a facile two‐step strategy involving electrodeposition and annealing processes.The morphology and s...A high‐quality polycrystalline bismuth vanadate(BiVO4)film was prepared on a fluorine‐doped tinoxide substrate via a facile two‐step strategy involving electrodeposition and annealing processes.The morphology and structural characterization of the resulting film were investigated by differentmethods including scanning electron microscopy,transmission electron microscopy,X‐ray diffraction(XRD),and Fourier transform infrared,ultraviolet‐visible(UV‐vis)absorption,and Ramanspectroscopies.XRD patterns as well as optical measurements revealed that BiVO4film crystallizedwith a pure monoclinic scheelite structure.The prepared BiVO4film was used for heterogeneousoxidation of chlorate ions in aqueous solution via electrochemical(EC),photochemical(PC),andphotoelectrochemical(PEC)processes.The decrease in concentration of chlorate was monitoredusing UV‐vis absorption spectroscopy.The results revealed that BiVO4could effectively performchlorate oxidation under light irradiation through a PEC method.The kinetics of chlorate oxidationwas consistent with a first‐order reaction,and the rate constant for the PEC process was found to bemuch higher than those of EC and PC.Furthermore,a possible photocatalytic oxidation mechanismfor chlorate mainly based on the formation of perchlorate ions is proposed.展开更多
文摘Annual haze in Northern Thailand has become increasingly severe,impacting health and the environment.How-ever,the sources of the haze remain poorly quantified due to limited observational data on aerosol molecular tracers.This study comprehensively investigates chemical composition of PM_(2.5),including both inorganic and organic compounds throughout haze and post-haze periods in 2019 at a rural site of Northern Thailand.Average PM_(2.5) concentrations during haze and post-haze period were 87±36 and 21±11μg/m^(3),respectively.Organic matter was the dominant contributor in PM_(2.5) mass,followed by water soluble inorganic ions and mineral dust.Molecular markers,including levoglucosan,dehydroabietic acid,and 4-nitrocatechol,and ions(Cl^(-),and K^(+)),were used to characterize low haze(PM_(2.5)<100μg/m^(3))and episodic haze(PM_(2.5)>100μg/m^(3)).Low haze is associated with local aerosols from agricultural waste burning,while episodic haze is linked to aged aerosols from mixed agricultural waste,softwood,and hardwood burning.Source apportionment incorporating these molecular markers in receptor modelling(Positive matrix factorization),identified three distinct biomass burning sources:mixed,local,and aged biomass burnings,contributing 31,19 and 13%of PM_(2.5) during haze period.During post-haze period,contributions shifted,with local biomass burning(32%)comparable to secondary sulfate(34%)and mixed dust and traffic sources(26%).These findings demonstrate that both regional and local sources con-tribute to severe haze,highlighting the need for integrated policies for cross-border cooperation as well as stricter regulations to reduce biomass burning in Northern Thailand and Southeast Asia.
基金supported by the Fundamental Research Funds for the National Natural Science Foundation of China 52225003,22208021,22109004the National Key R&D Program of China 2022YFB4101702.
文摘Although supported solid amine adsorbents have attracted great attention for CO_(2) capture,critical chemical deactivation problems including oxidative degradation and urea formation have severely restricted their practical applications for flue gas CO_(2) capture.In this work,we reveal that the nature of surface hydroxyl groups(metal hydroxyl Al–OH and nonmetal hydroxyl Si–OH)plays a key role in the deactivation mechanisms.The polyethyleneimine(PEI)supported on Al–OH-containing substrates suffers from severe oxidative degradation during the CO_(2) capture step due to the breakage of amine-support hydrogen bonding networks,but exhibits an excellent anti-urea formation feature by preventing dehydration of carbamate products under a pure CO_(2) regeneration atmosphere.In contrast,PEI supported on Si–OHcontaining substrates exhibits excellent anti-oxidative stability under simulated flue gas conditions by forming a robust hydrogen bonding protective network with Si–OH,but suffers from obvious urea formation during the pure CO_(2) regeneration step.We also reveal that the urea formation problem for PEI-SBA-15 can be avoided by the incorporation of an OH-containing PEG additive.Based on the intrinsic understanding of degradation mechanisms,we successfully synthesized an adsorbent 40PEI-20PEG-SBA-15 that demonstrates outstanding stability and retention of a high CO_(2) capacity of 2.45 mmol g^(−1) over 1000 adsorption–desorption cycles,together with negligible capacity loss during aging in simulated flue gas(10%CO_(2)+5%O_(2)+3%H_(2)O)for one month at 60–70℃.We believe this work makes great contribution to the advancement in the field of ultra-stable solid amine-based CO_(2) capture materials.
文摘Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM60B magnesium alloy in order to provide sufficient protection against the corrosion.The first composite(Ti-Zr/hybrid)was obtained via combination o f a hybrid sol-gel film(synthesized by mixing tetraethoxysilane(TEOS),and 3-glycidyloxypropyl-trimethoxysilane(GPTMS))as outer layer and Ti-Zr conversion coating as primer.Also,the second composite(Ti-Zr/PTMS)was applied in a similar manner by combination o f phenyl-trimethoxysilane(PTMS)so lgel film with the Ti-Zr conversion coating.The morphology and elemental composition of the Ti-Zr conversion film were assessed by the Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS),respectively.A cracky conversion film was applied on the alloy surface after immersion in the Ti-Zr conversion coating bath which was mainly composed of MgO,T i02,Zr02,and MgF2 compounds.Uniform,but not-adherent PTMS and hybrid sol-gel films(pure sol-gel films)with obvious defects were directly deposited onto the magnesium alloy without the Ti-Zr pretreatment which were morphologically characterized by the SEM.However,formation o f relatively uniform and completely defect-free Ti-Zr/hybrid and Ti-Zr/PTMS composites after using the Ti-Zr conversion coating as pretreatment was revealed by the SEM observations.In addition,the defects of the Ti-Zr conversion coating were completely filled by the sol-gel layers.The Ti-Zr/PTMS and Ti-Zr/hybrid composite coatings were provided much better corrosion protection capacity than the pure PTMS and hybrid sol-gel films,respectively which was confirmed by the Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)examinations in 0.05 M NaCl solution.
文摘Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.
文摘This work reports synthesis and characterization of heterocyclic functionalized polymers, poly（triazole-etherimidazole）s（PTAEI）, from a dialkyne-terminated compound, 3-（4,5-bis（4-（propargyloxy）phenyl）-1H-imidazol-2-yl）-9-ethyl-9H-carbazole, by using click reaction. PTAEIs were characterized and their properties such as solubility, thermal, mechanical, photophysical and metal ions adsorption were investigated. These polymers had weight average molar masses（Mw） in the range of 19100-26700 g/mol, exhibited excellent solubility in polar aprotic solvents and formed low-colored flexible thin films by solution casting method. They exhibited good thermal stability with glass transition temperatures（Tg） between 160 °C and 211 °C and 10% weight loss temperatures（T10%） in the range of 308-426 °C. Nanocomposites of PTAEIs with epoxide-terminated Fe3O4 showed that strong interfacial interaction between inorganic particles and the polymer matrix contributed to the enhanced thermal and mechanical properties. The photoluminescence intensity of the PTAEIs increased and the spectra red shifted with increasing Fe3O4 content. The PTAEIs and nanocomposites were tested for their extraction capability of metal ions from aqueous solutions either individually or in the mixture.
文摘A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The electrochemical behavior of captopril (CAP) at the surface of the modified electrode was investigated using electroanalytical methods. The modified electrode showed excellent electrocatalytic activity for the oxidation of CAP in aqueous solutions at physiological pH values. Cyclic voltammetric curves showed that the oxidation of CAP at the surface of the modified electrode reduced its overpotential by more than 290 mV. The modified electrode was used for detecting captopril using cyclic voltammetry and square wave voltammetry techniques. A calibration curve in the range of 0.03 to 2400 μmol/L was obtained that had a detection limit of 0.0096 μmol/L (3?) under the optimized conditions. The modified electrode was successfully used for the determination of captopril in pharmaceutical and biological samples.
文摘The inhibition effect of electrochemical noise, EIS and surface analysis to evaluate N'-bis (2-pyridylmethylidene)- 1,2-diiminoethane (BPIE) Schiff base against AZ91D alloy corrosion in 0.01 mol/L HCl was investigated by different electrochemical methods. Potentiodynamic polarization curves revealed that the BPIE acts as a mixed-type corrosion inhibitor. Electrochemical impedance spectroscopy (EIS) measurements confirmed the corrosion inhibition effect of the BPIE. As the inhibitor concentration increased, the charge transfer resistance increased and the double layer capacitance decreased due to more inhibitor adsorption on the surface. The results obtained by analysis of electrochemical noise (EN) data in time and frequency domains are in good agreement with EIS and polarization results. Moreover, scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) were used to investigate the corrosion inhibition of the BPIE. SEM images showed that the corrosion damage of the alloy surface reduced in the presence of BPIE. The intensity of the XRD peaks corresponding to magnesium-rich α phase increased in the presence of BPIE, indicating lower corrosion of alloy sample. Also, EDX analysis approved the corrosion inhibition performance of the BPIE. The studied Schiff base compound acts by physical adsorption on the alloy surface and its adsorption obeys the Langmuir isotherm.
基金the Fundamental Research Funds for the Central Universities(2016ZCQ03)Beijing Excellent Young Scholar(2015000026833ZK11)+1 种基金the National Natural Science Foundation of China(51622801,51572029,and 51308045)the Xu Guangqi grant
文摘Carbon dioxide(CO_(2))capture using magnesium oxide(MgO)-based adsorbents at intermediate temperatures has been regarded as a very prospective technology for their relatively high adsorption capacity,low cost,and wide availability.During the past few years,great effort has been devoted to the fabrication of molten salts-modified MgO-based adsorbents.The extraordinary progress achieved by coating with molten salts greatly promotes the COcapture capacity of MgO-based adsorbents.Therefore,we feel it necessary to deliver a timely review on this type of COcapturing materials,which will benefit the researchers working in both academic and industrial areas.In this work,we classified the molten saltsmodified MgO adsorbents into four categories:(1)homogenous molten salt-modified MgO adsorbents,(2)molten salt-modified double salts-based MgO adsorbents,(3)mixed molten salts-modified MgO adsorbents,and(4)molten salts-modified MgO-based mixed oxides adsorbents.This contribution critically reviews the recent developments in the synthetic method,adsorption capacity,reaction kinetics,promotion mechanism,operational conditions and regenerability of the molten salts-modified MgO COadsorbents.The challenges and prospects in this promising field of molten salts-modified MgO COadsorbents in real applications are also briefly mentioned.
基金supported by Higher Education Commission of Pakistan for Indigenous(Ph.D Fellowship for 5000 Scholars-PhaseⅡ)International Research Support Initiative Program(IRSIP)and Quaid-i-Azam University(URF/2015)
文摘Objective: To evaluate the total phenolic content and compare the antioxidant activity of various solvent extracts and fractions from the aerial parts of Coronopus didymus through various assays. Methods: Total phenolic content was determined using the Folin-Ciocalteu assay and the in vitro antioxidant activity of a number of different extracts was investigated in a dose-dependent manner with three different methods: the 2,2-diphenyl-1-picrylhydrazyl(DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt(ABTS) and ferric reducing antioxidant power(FRAP) assays. A flavone was isolated from the most active ethanolic extract with high antioxidant activity using size exclusion chromatography. IC_(50) values were calculated for the DPPH and ABTS methods. The FRAP activity was assessed in terms of μM Fe(II) equivalent. Results: The phenolic content was found to be highest in the ethanol extract(CDA Et; 47.8 mM GAE) and the lowest in the dichloromethane extract(CDA DCM; 3.13 mM GAE). The ethanol extract showed high radical scavenging activity towards DPPH and ABTS radicals with IC_(50) values of(7.80 × 10~2) and(4.32 × 10~2) μg/m L, respectively. The most active ethanol extract had a FRAP value of 1 921.7 μM Fe(Ⅱ) equivalent. The isolated flavone F10C(5,7,4'-trihydroxy-3'-methoxy flavone) was far more effective for scavenging free radicals in the DPPH and ABTS assays with IC_(50) of 43.8 and 0.08 μg/m L, than the standard trolox, with IC_(50) values of 97.5 and 21.1 μg/m L, respectively. In addition, the flavone F10C and the standard ascorbic acid had FRAP values of 1 621.7 and 16 038.0 μM Fe(Ⅱ) equivalents, respectively. Conclusions: The total phenolic content of extracts in decreasing order is ethanol extract(CDA Et)> acetone extract(CDA ACE)> phenolic extract(CDA MW)> n-hexane extract(CDA nHX)> chloroform extract(CDA CHL)> dichloromethane extract(CDA DCM). The ordering of extracts in terms of antioxidant activity from highest to lowest is CDA Et> CDA MW> CDA DCM> CDA CHL> CDA ACE> CDA nHX in DPPH, ABTS and FRAP assays. A significant relationship is found between antioxidant potential and total phenolic content, suggesting that phenolic compounds are the major contributors to the antioxidant activity of Coronopus didymus.
基金the AdFutura Scholarship provided by the Slovene Human Resources Development and Scholarship Fund for this workthe Clarendon and Balliol Jowett Scholarships for subsequent funding+1 种基金SCG Chemicals Co., Ltd. (Thailand)SCG Packaging Co. Ltd PLC, for funding
文摘A new solvothermal post-synthesis treatment for preparing high aspect ratio magnesium aluminium layered double hydroxides(Mg Al–LDHs) has been developed. Treating laurate-intercalated Mg Al–LDHs in pure ethanol in an autoclave for 48 h at 150 °C was found to produce delaminated MgA l–LDH nanosheets with a thickness of ~2.6 nm and an aspect ratio of ~105. It is proposed that the high pressure solvothermal process promotes the insertion of ethanol molecules into the LDH interlayer space, thereby facilitating delamination. This new post-synthesis treatment provides the opportunity for a facile, large scale route to highly delaminated high aspect ratio LDHs, which might be of interest towards novel nanomaterials for energy conversion and storage.
文摘A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine)(PMT)-modified glassy carbon electrode(GCE) to form a nano-Au/PMT composite-modified GCE(nano-Au/PMT/GCE).Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode.The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine(DA) and uric acid(UA) in phosphate buffer solution(pH = 7.00).Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0 ×10–8 to 10–6 mol/L for DA and 7.0 × 10–8 to 10–6 mol/L for UA.The detection limits were 3.7 × 10–8mol/L for DA and 4.5 × 10–8 mol/L for UA at a signal-to-noise ratio of 3.According to our experimental results,nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.
文摘Objective:To synthesis 2-substituted-4,5-diphenyl-N- alkyl imidazole derivatives,and evaluate their antibacterial activity.Methods:A mixture of benzil（10 mmol） and ammonium acetate（0.1 mol）（immediately fused） in glacial acetic acid（25 mL） was stirred at 80-100℃for 1 h under nitrogen atmosphere（to prevent incorporation of any atmospheric impurities and moisture）. Substituted aldehydes（10 mmol） in glacial acetic acid（5 mL） was added drop-wise over a period of 15-20 min at the same temperature and stirred for another 4 h,the progress of the reaction was monitored by TLC test using ethyl acetate as eluent.The newly synthesized compounds were characterized by IR,<sup>1</sup>HNMR,<sup>13</sup>CNMR and by mass spectroscopy.Results:All the synthesized compounds were confirmed by spectroscopical techniques and evaluated for antimicrobial activity against Staphylococcus aureus（S.aurius）,Bacilus subtilus（B.subtilus）,and Escheria coli （E.coli）.These compounds showed antibacterial activity（zone of inhibition） against S.aurius ranged from 3 mm to 9 mmin diameter,B.subtilus,4 -8 mm,and E.coli 5 -12 mm.Out of 2a-2e, only 2a and 2b showed some sort of activity but none of them had considerable activity compared with that of the standard.Conclusions:All the synthesized compounds show moderate activity against the tested bacteria S.aurius,B.subtilus,and E.coli.So,further structural modification is necessary to improve the antibacterial action of 2-substituted-4,5-diphenyl-N-alkyl imidazole derivatives.
文摘Five new optically active polyamides （PAs） 6a-6e were prepared by direct polycondensation reaction of 2-（1,3- isoindolinedione-2-yl）-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-Se in a medium consisting of triphenyl phosphite （TPP）, calcium chloride, pyridine （Py） and N-methyl-2-pyrrolidone （NMP）. The polycondensation reaction produced a series of polyamids 6a-6e in quantitative yields with inherent viscosities of 0.26-0.39 dL/g. The resulting polymers were fully characterized by means of ^1H-NMR, FT-1R spectroscopy, elemental analysis, inherent viscosity and specific rotation. Thermal properties of these polymers were investigated using thermal gravimetric analysis （TGA） and differential thermal gravimetry （DTG）. Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethyl acetamide （DMAc）, N,N-dimethyl formamide （DMF）, dimethyl sulfoxide （DMSO）, N-methyl-2-pyrrolidone （NMP） and sulfuric acid.
文摘Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, room temperature and surfactant free strategy which is able to form high surface area metal nanosponges with a three-dimensional（3D） porous structure. The structure of as-prepared nanosponges was characterized using the techniques of field emission scanning electron microscopy（FESEM）, energy dispersive spectroscopy（EDS） and cyclic voltammetry（CV）. Then, the electrocatalytic activities of Pd Ru NPNs towards formic acid oxidation were examined by electrochemical measurements including CV,chronoamperometry, and electrochemical impedance spectroscopy（EIS）. Based on studies, it was found that the current density of formic acid oxidation（FAO） is strongly dependent on the composition of Pd Ru NPNs. The best performance was realized for Pd;Ru;NPNs compared to monometallic Pd counterpart and other bimetallic NPNs which might be ascribed to the role of Ru in the decrease of CO adsorption strength on the catalyst and consequently the priority of formic acid oxidation through the direct pathway. The Pd;Ru;NPNs also showed the maximum current density and stability in chronoamperometric measurements. In addition, comparative studies were performed between as-prepared NPNs and CNTs-supported Pd nanoparticles（Pd NPs/CNTs）. The present results demonstrated the unique structural advantages of NPNs compared to individual Pd NPs supported on the CNT which leads to the promising performance of NPNs as supportless catalysts for the oxidation of formic acid.
文摘Novel dopamine-derivative compound,3,5-diamino-N-（3,4-dihydroxyphenethyl）benzamide（3,5-DAB）was prepared in two steps.In the first step dopamine hydrochloride was reacted with 3,5-dinitrobenzoyl chloride in the presence of propylene oxide.In the second step reduction of nitro groups resulted in preparation of 3,5-DAB in quantitative yield.This material was characterized using conventional spectroscopic methods such as FT-IR and ~1H NMR.In addition,the redox response of a modified carbon nanotubes paste electrode of 3,5-DAB was investigated in aqueous solution at a neutral pH.The result showed that the electrode process has a quasi-reversible response,withΔE_p,greater than the（59/n） mV expected for a reversible system.Finally,the diffusion coefficient for redox process in paraffin oil matrix obtained using chronoamperometry methods.
基金the Research Council of the University of Mohaghegh Ardabili for its financial support of this study
文摘The effect of a salicylic Schiff base componnd （Salcn） on the corrosion of AZ91 alloy in 30% ethylene glycol aqueous solution （30% EG/W） was investigated by electrochemical methods. Scanning electron microscope was used to observe the alloy surface in corrosive solution before and after the addition of inhibitor. There was no significant corrosion inhibition at the room temperature but high inhibition efficiencies were obtained at elevated temperatures due to the formation of chemisorbed inhibitor monolayer. As the inhibitor concentration increased, the inhibition efficiency increased probably due to more inhibitor adsorption on the alloy surface.
基金DST(No.SR/FTP/CS-114/2007) New Delhi.India for financial assistance.M.S.S. thanks to DST for scholarship
文摘A series of novel 5-benzylidene-3-（3-fluoro-4-yl-morpholin-4-yl-phenylimino）thiazolidin-4-one derivatives were synthesized using[bmIm]OH as a catalyst and were tested for their antibacterial and antifungal activities.These compounds showed moderate in vitro activities against the microorganisms tested.
文摘A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridine （Py） and dimethylformamide （DMF） system as condensing agent. The resulting thermally stable poly（amide-imide）s were obtained in good to high yields and inherent viscosities ranging between 0.35 dL/g and 0.58 dL/g and were characterized with FTIR, IH-NMR, CHN, Ultraviolet, TGA and DTG techniques.
基金Department of Science and Technology,India(No.SR/FT/CS-019/2008) for their financial support
文摘An efficient synthesis of tetrahydroquinoline derivatives is reported via three component coupling reactions of aldehydes and anilines with various dienophiles in the presence of a catalytic amount of perchloric acid adsorbed on silica gel（HClO;-SiO;） under mild reaction conditions.
文摘A high‐quality polycrystalline bismuth vanadate(BiVO4)film was prepared on a fluorine‐doped tinoxide substrate via a facile two‐step strategy involving electrodeposition and annealing processes.The morphology and structural characterization of the resulting film were investigated by differentmethods including scanning electron microscopy,transmission electron microscopy,X‐ray diffraction(XRD),and Fourier transform infrared,ultraviolet‐visible(UV‐vis)absorption,and Ramanspectroscopies.XRD patterns as well as optical measurements revealed that BiVO4film crystallizedwith a pure monoclinic scheelite structure.The prepared BiVO4film was used for heterogeneousoxidation of chlorate ions in aqueous solution via electrochemical(EC),photochemical(PC),andphotoelectrochemical(PEC)processes.The decrease in concentration of chlorate was monitoredusing UV‐vis absorption spectroscopy.The results revealed that BiVO4could effectively performchlorate oxidation under light irradiation through a PEC method.The kinetics of chlorate oxidationwas consistent with a first‐order reaction,and the rate constant for the PEC process was found to bemuch higher than those of EC and PC.Furthermore,a possible photocatalytic oxidation mechanismfor chlorate mainly based on the formation of perchlorate ions is proposed.
