Halogenated aromatic disinfection byproducts(DBPs)are gradually receiving attention due to their high detection frequency and usually higher toxicity than regulated DBPs.In this study,we established a solid phase extr...Halogenated aromatic disinfection byproducts(DBPs)are gradually receiving attention due to their high detection frequency and usually higher toxicity than regulated DBPs.In this study,we established a solid phase extraction(SPE)-LC-MS/MS method to simultaneously trace analyze 59 halogenated aromatic DBPs.The limits of detection and limits of quantification of halogenated aromatic DBPs ranged from 0.03 to 135.23 ng/L and from 0.1 to 450.76 ng/L,respectively.The range of recoveries and relative standard deviation(RSD)in river water were between 72.41%to 119.54%and 1.86%to 16.03%,respectively.Therefore,this method can be used to accurately analyze trace levels of halogenated aromatic DBPs in drinking water.The occurrence and transformation of halogenated aromatic DBPs were explored based on this method.In the chlorinated simulated source water and chlorinated river water,20 and 45 halogenated aromatic DBPs were determined,respectively.The active halogen species(HOCl,HOBr,and HOI)first reacted with natural organic matter(NOM)to form halogenated aromatic DBPs.Then,chlorine further reacted with the halogenated aromatic DBPs to convert them into small-molecule halogenated aliphatic DBPs through oxidation,electrophilic substitution,and hydrolysis reaction,etc.In the chlorinated simulated source water,chlorinated river water,and tap water,the toxicity contribution of bromoacetic acids(Br-HAAs)accounted for themajority(>71.16%).Given that halogenated aromatic DBPs are intermediate products of halogenated aliphatic DBPs,controlling the formation of halogenated aromatic DBPs is beneficial in decreasing the formation of halogenated aliphatic DBPs,thereby diminishing the toxicity of drinking water.展开更多
Perfluoronaphthenes,with inert chemical and biological properties and ability to dissolve large amounts of oxygen,have received the most attention in medical applications.However,the excessive anion contained may caus...Perfluoronaphthenes,with inert chemical and biological properties and ability to dissolve large amounts of oxygen,have received the most attention in medical applications.However,the excessive anion contained may cause some side effects.Herein,liquid-liquid extraction technique with shaking and ultrasonic extraction was used for the trace analysis of five anions(F^(-),Cl^(-),NO_(3)^(-),PO_(4)^(3-),SO_(4)^(2-))in perfluorodecalin using water as green extractant.The optimum pretreatment technology and ion chromatography detection conditions were established.Good linearity was observed in each concentration range,and the linear correlation coefficient(R^(2))was better than 0.997.The limits of detection(S/N=3)of five anions from perfluorodecalin were 3.2,5.5,14.2,23.2 and 29.5μg/L,respectively.The established method with high sensitivity and accuracy has been successfully appliedfor the determination of five anions in three perfluorodecalin products,which provides a basis for further development of green detection and quality standard formulation in perfluorodecalin and other fluorocarbon solvents.展开更多
The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion m...The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion method is superior in comparison with the conventional thermal acid digestion method as it leads to higher recovery, better reproducibility, lower volatility loss, better protection against environmental contamination and much less digestion time (5 minutes vs. 24 hours). The use of eluent as extractant is shown to reduce the water dip problem in the chro-matogram. The addition of chelating agent in the eluent coupled with UV detection is shown to provide satisfactory chromatographic separation and good sensitivity for the analysis of transition metals present in the air particulate matter. Using the U.S. National Bureau of Standards Reference Material 1648 Urban Particulate Matter as standard for checking, the analytical procedure is shown to give good recovery and reproducibility for the detection of the following cations and anions in air particulate matter: Fe2 Cu, Mn, Pb, Zn, Mg, Na, HN4+, Cl-, NO3- and SO42-. Field test was also performed to check the applicability of the method and the results obtained were discussed in the present paper.展开更多
Trace metals associated with PM10 aerosols and their variation during day and nighttime as well as during different seasons have been studied for the year 2012. PCA analysis suggested5 PCs,which accounted for 86.8% cu...Trace metals associated with PM10 aerosols and their variation during day and nighttime as well as during different seasons have been studied for the year 2012. PCA analysis suggested5 PCs,which accounted for 86.8% cumulative variance. PC1 accounted for 30% with a significant loading of metals of anthropogenic origin,while PC2 showed 28% variance with the loading of metals of crustal origin. These trace metals showed seasonal distinct day and night time characteristics. The concentrations of Cu,Pb,and Cd were found to be higher during nighttime in all the seasons. Only Fe was observed with significantly higher mean concentrations during daytime of all seasons except monsoon. The highest mean values of Cu,Cd,Zn,and Pb during post-monsoon might be attributed to winds advection over the regions of waste/biomass burning and industrial activities in Punjab and Haryana regions.Furthermore,concentration weighted trajectory analysis suggested that metals of crustal origin were contributed by long-range transport while metals of anthropogenic and industrial activities were contributed by regional/local source regions.展开更多
In this paper,a new method for simultaneous spectrophotometric analysis of multi- component with double-system was developed.The multivariate calibration method,principal component analysis-partial least squares(PCA-P...In this paper,a new method for simultaneous spectrophotometric analysis of multi- component with double-system was developed.The multivariate calibration method,principal component analysis-partial least squares(PCA-PLS),was described and applied to the processing of measurement data.A demonstration,simultaneous determination of cobalt,nickel,copper,zinc and iron with double-system(5-Br-PADAP and PAR as chromogenic chelate reagents,respectively) was given.The results showed that the method with douhle-system gave better precision than those with single system and MLR(in this paper,AKC method was selected)did not give satis- fied precision in any situation.展开更多
In Garze Tibetan autonomous prefecture inSichuan province, China, 41 echinococciasis patientswho had received surgical treatment were recruitedin the study, and 82 health persons who had livedin Garze for at least 10 ...In Garze Tibetan autonomous prefecture inSichuan province, China, 41 echinococciasis patientswho had received surgical treatment were recruitedin the study, and 82 health persons who had livedin Garze for at least 10 years were selected ascontrols. The serum levels of Zn, Se and Cu of thecases and controls were detected. The resultsshowed that most echinococciasis cases weredistributed in Shiqu county （17.1%, 7/41）, and only1 case was distributed in Yajiang county （2.4%）. Themale to female ratio of the cases was 1：1.56. Theechinococciasis patients were mainly aged 30-39years （36.59%, 15/41）. And, the cases aged 20-49years accounted for 68.29% （28/41）. Comparedwith health controls, the serum levels of Zn and Seof the cases significantly declined. However, theserum level of Cu of the cases had no significantlychange. It was confirmed that the serum levels ofZn and Se were interrelated with the prevalence ofechinococciasis.展开更多
The COVID-19 pandemic has underscored the critical need for rapid and accurate diagnostic tools.Current methods,including Polymerase Chain Reaction and rapid antigen tests(RAT),have limitations in speed,sensitivity,an...The COVID-19 pandemic has underscored the critical need for rapid and accurate diagnostic tools.Current methods,including Polymerase Chain Reaction and rapid antigen tests(RAT),have limitations in speed,sensitivity,and the requirement for specialized equipment and trained personnel.Nanotechnology,particularly upconversion nanoparticles(UCNPs),offer a promising alternative due to their unique optical properties.UCNPs can convert low-energy near-infrared light into higher-energy visible light,making them ideal for use as optical probes in single molecule detection and point of care applications.This study,initiated in early 2020,explores the opportunity of using highly doped UCNPs(40%Yb^(3+)/4%Er^(3+))in lateral flow assay(LFA)for the early diagnosis of COVID-19.The UCNPsbased LFA testing demonstrated a minimum detection concentration of 100 pg/mL for SARS-CoV-2 antigen and 10^(5)CCID_(50)/mL for inactivated virus.Clinical trials,conducted in Malaysia and Western Australia independently,showed that the technique was at least 100 times more sensitive than commercial RAT kits,with a sensitivity of 100%and specificity of 91.94%.The development process involved multidisciplinary collaborations,resulting in the Virulizer device,an automated strip reader for point-of-care testing.This work sets a reference for future development of highly sensitive and quantitative RAT,aiming for the Limits of Detection in the range of sub-ng/mL.展开更多
This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical sl...This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical slip trace analysis and electron backscatter diffraction.The studied regions covered a total of 1150 grains,in which 136 sets of slip traces were identified and analyzed in detail.The basalslip always dominated the deformation,whose frequencies decreased(from 81.0%to 62.5%)with increasing GS(from 10 to 85μm).The prismaticslip activity increased from 10.8%(10μm)to 27.5%(85μm),while that for pyramidal II<c+a>slip was almost constant.Critical resolved shear stress(CRSS)ratios were estimated based on the identified slip activity statistics,and then the Hall-Petch coefficients(k)of individual slip modes were calculated.The k value for prismaticslip(194 MPa·μm^(1/2))was lower than that for pyramidal II<c+a>slip(309 MPa·μm^(1/2)),which implies that pyramidal II<c+a>slip was more GS sensitive.Twinning activity exhibited a positive correlation with GS,though it remained limited partly due to the unfavorable loading direction.The macroscopic Hall-Petch relationship was divided into two regions,i.e.,the k value(753 MPa·μm^(1/2))for the coarse-grain region(30-85μm)was significantly larger than that(118 MPa·μm^(1/2))of the fine-grain region(10-30μm),which could be attributed to the transition of predominant deformation mechanisms from slip to slip combined twinning with increasing GS.This work provides detailed and quantitative experimental data of the GS effects on individual slip activities of Mg and provides new insights into the Hall-Petch relationship for individual slip modes.展开更多
Radioactive noble-gas isotopes, SSKr （half-life tl/2=10.8 y）, 39Ar （tl/2=269 y）, and SlKr （t1/2-229,000 y）, are ideal tracers and can be detected by atom trap trace analysis （ATTA）, a laser-based technique, fr...Radioactive noble-gas isotopes, SSKr （half-life tl/2=10.8 y）, 39Ar （tl/2=269 y）, and SlKr （t1/2-229,000 y）, are ideal tracers and can be detected by atom trap trace analysis （ATTA）, a laser-based technique, from environmental samples like air and groundwater. Prior to ATTA measurements, it is necessary to efficiently extract krypton and argon gases from samples. Using a combination of cryogenic distillation, titanium chemical reaction and gas chromatography, we demonstrate that we can recover both krypton and argon gases from 1-10 L ＂air-like＂ samples with yields in excess of 90% and 98%, respectively, which meet well the requirements for ATTA measurements. A group of testing samples are analyzed to verify the performance of the system, including two groundwater samples obtained from north China plain.展开更多
The micro-amount of nickel in MnO2, electrolytical and natural both, was determined by differential pulse polarography. NH4OH-NH4Cl was used as supporting electrolyte. It was found that the peak potential of Ni(II) re...The micro-amount of nickel in MnO2, electrolytical and natural both, was determined by differential pulse polarography. NH4OH-NH4Cl was used as supporting electrolyte. It was found that the peak potential of Ni(II) reduction wave is -1.0V (vs. Ag-AgCl electrode). The presence of great amount of Mn(II) does not interfere in the trace nickel determination. the peak current relationship with the Ni2+ concentration presents a quite fine straight line. The differential pulse polarography is proved that it is a simple, reliable and acceptable method for determination of trace Ni in various species of MnO2.展开更多
Ultra trace determination of lantanum（Ⅲ） has been studied by adsorptive stripping voltammetry methods using an alizarin S as complexing agent and carbon paste electrode as working electrode. The electrode was made ...Ultra trace determination of lantanum（Ⅲ） has been studied by adsorptive stripping voltammetry methods using an alizarin S as complexing agent and carbon paste electrode as working electrode. The electrode was made from mixed of carbon powder and paraffin in micropipette tip with diameter of 4 ram. This method consists of two steps. The first step is the formation and adsorptive accumulation of metal ion with chelator at the electrode surface. The second step is stripping the complex from the electrode surface into the solution. The stripping step generates current which is recorded as voltammogram. The optimum conditions of instrumental parameter obtained were accumulation potential of 600 mV, accumulation time of 120 seconds, and pH of solution of 5.5. In this research, the limit detection obtained was 2.3348 × 10^-12 M （3.24× 10^-11μg/L） with sensitivity of 16.52 （nA/10u M） and the precision of standard solution of La3＋ with concentration of 2 × 10^-12 M, 4× 10^-12 M, 6 × 10^-12 M, 8 × 10^-12 M, and 10 × 10^-12M were 3.50%, 9.88%, 7.19%, 7.48% and 1.85% respectively. The linierity of this method is very good with correlation coefficient is 0.9780. Recovery percentage from La3＋ with concentration of 6× 10^-12 M and 10 × 10^-12 M are 108.84% and 91.51%, respectively.展开更多
Developing a rapid and precise method for trace element analysis in geothermal water is crucial due to its high total dissolved solids and salinity,which can impact element determination.In this study,we optimized the...Developing a rapid and precise method for trace element analysis in geothermal water is crucial due to its high total dissolved solids and salinity,which can impact element determination.In this study,we optimized the determination of ferrum,manganese,strontium and barium in geothermal water samples collected from different regions.A matrix matching method was established for accurate quantification using Inductively Coupled Plasma Optical Emission Spectroscopy(ICP-OES).Instrumental conditions and experimental parameters were optimized,and the influence of storage medium and storage duration on measurement accuracy were evaluated.The results demonstrated that storing geothermal water samples in 1%nitric acid had no significant impact on measurement results over an eight-week period.Calibration curve correlation coefficients exceeded 0.9998 for all target elements.The detection limits of this method ranged from 0.0002 mg/L to 0.0031 mg/L,with Relative Standard Deviations(RSD)were 0.07%–2.33%,and spike recovery rates were from 96.8%to 103.2%.The obtained data were consistent with results from the standard addition method and dilution method,demonstrating the reliability of this approach.This method offers low detection limits,high precision and excellent recovery rate,providing a robust reference for the accurate determination of ferrum,manganese,strontium and barium in geothermal water,thereby laying a solid foundation for the development and utilization of geothermal resources.展开更多
Trace metals in PM2.5 were measured at one industrial site and one urban site during September, 2010 in Ji＇nan, eastern China. Individual aerosol particles and PM2.5 samples were collected concurrently at both sites....Trace metals in PM2.5 were measured at one industrial site and one urban site during September, 2010 in Ji＇nan, eastern China. Individual aerosol particles and PM2.5 samples were collected concurrently at both sites. Mass concentrations of eleven trace metals （i.e., Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, and Pb） and one metalloid （i.e., As） were measured by inductively coupled plasma atomic emission spectroscopy （ICP-AES）. The result shows that mass concentrations of PM2.5 （130μg/m3） and trace metals （4.03 μg/m3） at the industrial site were 1.3 times and 1.7 times higher than those at the urban site, respectively, indicating that industrial activities nearby the city can emit trace metals into the surrounding atmosphere. Fe concentrations were the highest among all the measured trace metals at both sites, with concentrations of 1.04 ixg/m 3 at the urban site and 2.41 Itg/m3 at the industrial site, respectively. In addition, Pb showed the highest enrichment factors at both sites, suggesting the emissions from anthropogenic activities existed around the city. Correlation coefficient analysis and principal component analysis revealed that Cu, Fe, Mn, Pb, and Zn were originated from vehicular traffic and industrial emissions at both sites; As, Cr, and part of Pb from coal-fired power plant; Ba and Ti from natural soil. Based on the transmission electron microscopy analysis, we found that most of the trace metals were internally mixed with secondary sulfate/organic particles. These internally mixed trace metals in the urban air may have different toxic abilities compared with externally mixed trace metals.展开更多
This article presents a mathematical model of helical end-milling forces through experimental identification of the cutting coefficients and analyzes the changes of comer-milling forces under different conditions. In ...This article presents a mathematical model of helical end-milling forces through experimental identification of the cutting coefficients and analyzes the changes of comer-milling forces under different conditions. In allusion to the corner-milling process, the relationship between working parameters and the comer coordinates is investigated by way of combination of tool tracing and cutting geometrodynamics. The milling parameters are optimized by changing the coordinates of tool center and working parameters without altering curing forces. By applying the optimized parameters to milling practice, a comparison is made to show the improved product quality. Based on these optimized parameters, a finite element method （FEM） program is used to compute deformation values of a workpiece＇s comer, which evidences few effects that optimized parameters can exert on the comer deformation.展开更多
Deformation behavior of 1 Al containing Mg alloy has been investigated in the present study.After annealing,the Mg-1 Al alloy shows a typical basal texture.When compared to the pure Mg having a similar texture and gra...Deformation behavior of 1 Al containing Mg alloy has been investigated in the present study.After annealing,the Mg-1 Al alloy shows a typical basal texture.When compared to the pure Mg having a similar texture and grain size,the Mg-1 Al alloy shows much higher strength and larger elongation.Slip trace analyses of the tensile strained specimens show that non-basal slips such as pyramidal I and II slips can be easily activated at an early stage of deformation in the Mg-1 Al alloy and the grains in the Mg-1 Al alloy are seen to accommodate a larger degree of deformation than those in the pure Mg at a given strain.With increasing tensile strain,however,there is a strain localization along the initially formed slip lines of non-basal slips,forming surface steps without activating multiple slip lines.展开更多
This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in Mg-Zn and Mg-Al alloys. With tha...This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in Mg-Zn and Mg-Al alloys. With that aim, four solid solution Mg-Zn and Mg-Al binary alloy ingots containing 1 and 2 wt.% solute atoms were subjected to hot rolling and subsequent annealing to generate polycrystals with similar average grain size and basal-type texture for each composition. The activity of the different slip systems after tensile testing at 150°C and at 250°C was evaluated in pure Mg and in the alloys by EBSD-assisted slip trace analysis. In addition, segregation of Zn and Al atoms at grain boundaries during the thermo-mechanical processing was characterized by HAADF-STEM and EDX. It was found that while the addition of Al and Zn atoms to pure Mg does not lead to major changes in the mechanical strength at the investigated temperatures, it does enhance ductility significantly, especially at 250℃. Our results show that this increase in ductility cannot be attributed to a higher activation of non-basal systems in the alloys, as reported earlier, as the incidence of non-basal systems is indeed considerably higher in pure Mg. This work suggests, on the contrary, that the ductility increase may be attributed to the presence of a more homogenous basal activity in the alloys due to a lower degree of orientation clustering, to grain boundary solute segregation, and to a higher slip diffusivity at grain interiors.展开更多
In the determination of trace yttrium (Y) in an ytterbium (Yb) matrix byinductively coupled plasma atomic emission spectrometry (ICP-AES), the most prominent line ofyttrium, Y 371.030 nm line, suffers from strong inte...In the determination of trace yttrium (Y) in an ytterbium (Yb) matrix byinductively coupled plasma atomic emission spectrometry (ICP-AES), the most prominent line ofyttrium, Y 371.030 nm line, suffers from strong interference due to an emission line of ytterbium.In mis work, a method based on wavelet transform was proposed for the spectral interferencecorrection. Haar wavelet was selected as the mother wavelet. The discrete detail after the thirddecomposition, D3, was chosen for quantitative analysis based on the consideration of bothseparation degree and peak height. The linear correlation coefficient between the height of the leftpositive peak in D3 and the concentration of Y was calculated to be 0.9926. Six synthetic sampleswere analyzed, and the recovery for yttrium varied from 96.3 percent to 110.0 percent. The amountsof yttrium in three ytterbium metal samples were determined by the proposed approach with an averagerelative standard deviation (RSD) of 2.5 percent, and the detection limit for yttrium was 0.016percent. This novel correction technique is fast and convenient, since neither complicated modelassumption nor time-consuming iteration is required. Furthermore, it is not affected by thewavelength drift inherent in monochromators that will severely reduce the accuracy of resultsobtained by some chemometric methods.展开更多
Extensive application of nuclear energy has caused widespread environmental uranium contamination.New detection approaches without complicated sample pretreatment and precision instruments are in demand for on-site an...Extensive application of nuclear energy has caused widespread environmental uranium contamination.New detection approaches without complicated sample pretreatment and precision instruments are in demand for on-site and in-time determination of uranyl ions in environmental monitoring, especially in an emergency situation. In this work, a simple and effective fluorescent sensor(Z)-N’-hydroxy-4-(1,2,2-triphenylvinyl)benzimidamide(TPE-A) with aggregation-induced emission(AIE) character was established and studied. It could realize to detect UO_(2)2+via quenching the fluorescence of its aggregation-induced emission, with good selectivity and sensitivity. Such strategy shows a wide linear range from 5.0 × 10^(-8)mol/L to 4.5 × 10^(-7)mol/L(R^(2)= 0.9988) with exceptional sensitivity reaching 4.7 × 10^(-9)mol/L, which is far below the limit for uranium in drinking water(30 μg/L, ca. 1.1 × 10-7mol/L) stipulated by the WHO.A response time less than four minutes make it rapid for uranyl ion measurement. It was applied for detection of uranyl ion in spiked river water samples with recoveries in the range of 98.7%-104.0%, comparable to those obtained by ICP-MS. With the advantages of portable apparatus, rapid detection process and high sensitivity, TPE-A can serve as a promising fluorescent sensor for the detection of UO_(2)2+in environmental water samples.展开更多
Although tension-compression(T-C)asymmetry in yield strength was rarely documented in coarse-grained face centered cubic(FCC)metals as critical resolved shear stress(CRSS)for dislocation slip differs little between te...Although tension-compression(T-C)asymmetry in yield strength was rarely documented in coarse-grained face centered cubic(FCC)metals as critical resolved shear stress(CRSS)for dislocation slip differs little between tension and compression,the T-C asymmetry in strength,i.e.,higher strength when loaded in compression than in tension,was reported in some FCC high entropy alloys(HEAs)due to twinning and phase transitions activated at high strain regimes in compression.In this paper,we demonstrate a reversed and atypical tension-compression asymmetry(tensile strength markedly exceeds compressive strength)in a non-equiatomic FCC Ni_(2)CoFeV_(0.5)Mo_(0.2) medium entropy alloy(MEA)under dynamic loading,wherein dislocation slip governs dynamic deformation without twins or phase transitions.The asymme-try can be primarily interpreted as higher CRSS and more hard slip modes(lower average Schmid factor)activated in grains under dynamic tension than compression.Besides,larger strain rate sensitivity in dy-namic tension overwhelmingly contributes to the higher flow stress,thanks to the occurrence of more immobile Lomer-locks,narrower spacing of planar slip bands and higher dislocation density.This finding may provide some insights into designing MEAs/HEAs with desired properties under extreme conditions such as blast,impact and crash.展开更多
A Nicolet-200SXV FT-IR spectrometer combined with an exciting light set-up has been applied to determine the shallow impurity concentration in detector-grade silicon. The detection sensitivity of boron concentration i...A Nicolet-200SXV FT-IR spectrometer combined with an exciting light set-up has been applied to determine the shallow impurity concentration in detector-grade silicon. The detection sensitivity of boron concentration is high up to 7.8 × 10-12. The calibration curve of boron concentration in high-purity silicon has been obtained, from which the experimental value of calibration factor of boron concentration in silicon is demonstrated to be 1.15 × 1013 cm-1.展开更多
基金supported by the National Natural Science Foundation of China(No.52300005)China Postdoctoral Science Foundation(No.2023TQ0098)+5 种基金Heilongjiang Postdoctoral Fund(No.LBH-Z23175)Heilongjiang Touyan Innovation Team Program(No.HIT-SE-01)the Crossover Fund of Medical Engineering Science of Harbin Institute of Technology(No.IR2021107)the National Natural Science Foundation of International(Regional)Cooperation and Exchange Project(No.51961125104)the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2022TS15)the Ecological and Environmental Protection Research Project of Heilongjiang Province(No.HST2022ST006).
文摘Halogenated aromatic disinfection byproducts(DBPs)are gradually receiving attention due to their high detection frequency and usually higher toxicity than regulated DBPs.In this study,we established a solid phase extraction(SPE)-LC-MS/MS method to simultaneously trace analyze 59 halogenated aromatic DBPs.The limits of detection and limits of quantification of halogenated aromatic DBPs ranged from 0.03 to 135.23 ng/L and from 0.1 to 450.76 ng/L,respectively.The range of recoveries and relative standard deviation(RSD)in river water were between 72.41%to 119.54%and 1.86%to 16.03%,respectively.Therefore,this method can be used to accurately analyze trace levels of halogenated aromatic DBPs in drinking water.The occurrence and transformation of halogenated aromatic DBPs were explored based on this method.In the chlorinated simulated source water and chlorinated river water,20 and 45 halogenated aromatic DBPs were determined,respectively.The active halogen species(HOCl,HOBr,and HOI)first reacted with natural organic matter(NOM)to form halogenated aromatic DBPs.Then,chlorine further reacted with the halogenated aromatic DBPs to convert them into small-molecule halogenated aliphatic DBPs through oxidation,electrophilic substitution,and hydrolysis reaction,etc.In the chlorinated simulated source water,chlorinated river water,and tap water,the toxicity contribution of bromoacetic acids(Br-HAAs)accounted for themajority(>71.16%).Given that halogenated aromatic DBPs are intermediate products of halogenated aliphatic DBPs,controlling the formation of halogenated aromatic DBPs is beneficial in decreasing the formation of halogenated aliphatic DBPs,thereby diminishing the toxicity of drinking water.
基金supported by the Zibo Key Scientific Research program(2019gy010020)the Jinan Customs Science and Technology Plan(2020JK012)
文摘Perfluoronaphthenes,with inert chemical and biological properties and ability to dissolve large amounts of oxygen,have received the most attention in medical applications.However,the excessive anion contained may cause some side effects.Herein,liquid-liquid extraction technique with shaking and ultrasonic extraction was used for the trace analysis of five anions(F^(-),Cl^(-),NO_(3)^(-),PO_(4)^(3-),SO_(4)^(2-))in perfluorodecalin using water as green extractant.The optimum pretreatment technology and ion chromatography detection conditions were established.Good linearity was observed in each concentration range,and the linear correlation coefficient(R^(2))was better than 0.997.The limits of detection(S/N=3)of five anions from perfluorodecalin were 3.2,5.5,14.2,23.2 and 29.5μg/L,respectively.The established method with high sensitivity and accuracy has been successfully appliedfor the determination of five anions in three perfluorodecalin products,which provides a basis for further development of green detection and quality standard formulation in perfluorodecalin and other fluorocarbon solvents.
文摘The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion method is superior in comparison with the conventional thermal acid digestion method as it leads to higher recovery, better reproducibility, lower volatility loss, better protection against environmental contamination and much less digestion time (5 minutes vs. 24 hours). The use of eluent as extractant is shown to reduce the water dip problem in the chro-matogram. The addition of chelating agent in the eluent coupled with UV detection is shown to provide satisfactory chromatographic separation and good sensitivity for the analysis of transition metals present in the air particulate matter. Using the U.S. National Bureau of Standards Reference Material 1648 Urban Particulate Matter as standard for checking, the analytical procedure is shown to give good recovery and reproducibility for the detection of the following cations and anions in air particulate matter: Fe2 Cu, Mn, Pb, Zn, Mg, Na, HN4+, Cl-, NO3- and SO42-. Field test was also performed to check the applicability of the method and the results obtained were discussed in the present paper.
基金Partial financial support from the CSIR network project(PSC 0112)CSIR fellowship to Subhash Chandra,SRF
文摘Trace metals associated with PM10 aerosols and their variation during day and nighttime as well as during different seasons have been studied for the year 2012. PCA analysis suggested5 PCs,which accounted for 86.8% cumulative variance. PC1 accounted for 30% with a significant loading of metals of anthropogenic origin,while PC2 showed 28% variance with the loading of metals of crustal origin. These trace metals showed seasonal distinct day and night time characteristics. The concentrations of Cu,Pb,and Cd were found to be higher during nighttime in all the seasons. Only Fe was observed with significantly higher mean concentrations during daytime of all seasons except monsoon. The highest mean values of Cu,Cd,Zn,and Pb during post-monsoon might be attributed to winds advection over the regions of waste/biomass burning and industrial activities in Punjab and Haryana regions.Furthermore,concentration weighted trajectory analysis suggested that metals of crustal origin were contributed by long-range transport while metals of anthropogenic and industrial activities were contributed by regional/local source regions.
基金This project was supported by the Natural Science Foundation of Jiangxi Province
文摘In this paper,a new method for simultaneous spectrophotometric analysis of multi- component with double-system was developed.The multivariate calibration method,principal component analysis-partial least squares(PCA-PLS),was described and applied to the processing of measurement data.A demonstration,simultaneous determination of cobalt,nickel,copper,zinc and iron with double-system(5-Br-PADAP and PAR as chromogenic chelate reagents,respectively) was given.The results showed that the method with douhle-system gave better precision than those with single system and MLR(in this paper,AKC method was selected)did not give satis- fied precision in any situation.
基金financially supported by the Grant for the National Major Science and Technology Project(grant No.2012ZX10004-220,No.2008ZX10004-011)
文摘In Garze Tibetan autonomous prefecture inSichuan province, China, 41 echinococciasis patientswho had received surgical treatment were recruitedin the study, and 82 health persons who had livedin Garze for at least 10 years were selected ascontrols. The serum levels of Zn, Se and Cu of thecases and controls were detected. The resultsshowed that most echinococciasis cases weredistributed in Shiqu county （17.1%, 7/41）, and only1 case was distributed in Yajiang county （2.4%）. Themale to female ratio of the cases was 1：1.56. Theechinococciasis patients were mainly aged 30-39years （36.59%, 15/41）. And, the cases aged 20-49years accounted for 68.29% （28/41）. Comparedwith health controls, the serum levels of Zn and Seof the cases significantly declined. However, theserum level of Cu of the cases had no significantlychange. It was confirmed that the serum levels ofZn and Se were interrelated with the prevalence ofechinococciasis.
基金approved by the Ethics Committee at the University of Technology Sydney(ETH22-7241)written informed consent(according to the UTS clinical trial declaration)was obtained from all patients before the COVID-19 testing.
文摘The COVID-19 pandemic has underscored the critical need for rapid and accurate diagnostic tools.Current methods,including Polymerase Chain Reaction and rapid antigen tests(RAT),have limitations in speed,sensitivity,and the requirement for specialized equipment and trained personnel.Nanotechnology,particularly upconversion nanoparticles(UCNPs),offer a promising alternative due to their unique optical properties.UCNPs can convert low-energy near-infrared light into higher-energy visible light,making them ideal for use as optical probes in single molecule detection and point of care applications.This study,initiated in early 2020,explores the opportunity of using highly doped UCNPs(40%Yb^(3+)/4%Er^(3+))in lateral flow assay(LFA)for the early diagnosis of COVID-19.The UCNPsbased LFA testing demonstrated a minimum detection concentration of 100 pg/mL for SARS-CoV-2 antigen and 10^(5)CCID_(50)/mL for inactivated virus.Clinical trials,conducted in Malaysia and Western Australia independently,showed that the technique was at least 100 times more sensitive than commercial RAT kits,with a sensitivity of 100%and specificity of 91.94%.The development process involved multidisciplinary collaborations,resulting in the Virulizer device,an automated strip reader for point-of-care testing.This work sets a reference for future development of highly sensitive and quantitative RAT,aiming for the Limits of Detection in the range of sub-ng/mL.
基金supported by the National Natural Science Foundation of China(No.52171125)the Sichuan Science and Technology Program(No.2024NSFSC0193).
文摘This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical slip trace analysis and electron backscatter diffraction.The studied regions covered a total of 1150 grains,in which 136 sets of slip traces were identified and analyzed in detail.The basalslip always dominated the deformation,whose frequencies decreased(from 81.0%to 62.5%)with increasing GS(from 10 to 85μm).The prismaticslip activity increased from 10.8%(10μm)to 27.5%(85μm),while that for pyramidal II<c+a>slip was almost constant.Critical resolved shear stress(CRSS)ratios were estimated based on the identified slip activity statistics,and then the Hall-Petch coefficients(k)of individual slip modes were calculated.The k value for prismaticslip(194 MPa·μm^(1/2))was lower than that for pyramidal II<c+a>slip(309 MPa·μm^(1/2)),which implies that pyramidal II<c+a>slip was more GS sensitive.Twinning activity exhibited a positive correlation with GS,though it remained limited partly due to the unfavorable loading direction.The macroscopic Hall-Petch relationship was divided into two regions,i.e.,the k value(753 MPa·μm^(1/2))for the coarse-grain region(30-85μm)was significantly larger than that(118 MPa·μm^(1/2))of the fine-grain region(10-30μm),which could be attributed to the transition of predominant deformation mechanisms from slip to slip combined twinning with increasing GS.This work provides detailed and quantitative experimental data of the GS effects on individual slip activities of Mg and provides new insights into the Hall-Petch relationship for individual slip modes.
基金This work was supported by the Special Fund for Land and Resources Research in the Public Interest （No.201511046） and the National Natural Science Foundation of China （No.21225314 and No.41102151）. We would like to give our gratitude to Zong-yu Chen from IHEG for organizing the field campaign.
文摘Radioactive noble-gas isotopes, SSKr （half-life tl/2=10.8 y）, 39Ar （tl/2=269 y）, and SlKr （t1/2-229,000 y）, are ideal tracers and can be detected by atom trap trace analysis （ATTA）, a laser-based technique, from environmental samples like air and groundwater. Prior to ATTA measurements, it is necessary to efficiently extract krypton and argon gases from samples. Using a combination of cryogenic distillation, titanium chemical reaction and gas chromatography, we demonstrate that we can recover both krypton and argon gases from 1-10 L ＂air-like＂ samples with yields in excess of 90% and 98%, respectively, which meet well the requirements for ATTA measurements. A group of testing samples are analyzed to verify the performance of the system, including two groundwater samples obtained from north China plain.
文摘The micro-amount of nickel in MnO2, electrolytical and natural both, was determined by differential pulse polarography. NH4OH-NH4Cl was used as supporting electrolyte. It was found that the peak potential of Ni(II) reduction wave is -1.0V (vs. Ag-AgCl electrode). The presence of great amount of Mn(II) does not interfere in the trace nickel determination. the peak current relationship with the Ni2+ concentration presents a quite fine straight line. The differential pulse polarography is proved that it is a simple, reliable and acceptable method for determination of trace Ni in various species of MnO2.
文摘Ultra trace determination of lantanum（Ⅲ） has been studied by adsorptive stripping voltammetry methods using an alizarin S as complexing agent and carbon paste electrode as working electrode. The electrode was made from mixed of carbon powder and paraffin in micropipette tip with diameter of 4 ram. This method consists of two steps. The first step is the formation and adsorptive accumulation of metal ion with chelator at the electrode surface. The second step is stripping the complex from the electrode surface into the solution. The stripping step generates current which is recorded as voltammogram. The optimum conditions of instrumental parameter obtained were accumulation potential of 600 mV, accumulation time of 120 seconds, and pH of solution of 5.5. In this research, the limit detection obtained was 2.3348 × 10^-12 M （3.24× 10^-11μg/L） with sensitivity of 16.52 （nA/10u M） and the precision of standard solution of La3＋ with concentration of 2 × 10^-12 M, 4× 10^-12 M, 6 × 10^-12 M, 8 × 10^-12 M, and 10 × 10^-12M were 3.50%, 9.88%, 7.19%, 7.48% and 1.85% respectively. The linierity of this method is very good with correlation coefficient is 0.9780. Recovery percentage from La3＋ with concentration of 6× 10^-12 M and 10 × 10^-12 M are 108.84% and 91.51%, respectively.
基金supported jointly by National Natural Science Foundation of China(NO.42430718)National Natural Science Foundation of China(NO.42077179)+2 种基金Natural Science Foundation of Fujian Province of China(NO.2023J01227)Natural Science Foundation of Xiamen,China(NO.3502Z20227309)Basic Scientific Research Business Expenses Project of the Chinese Academy of Geological Sciences(NO.YK202303).
文摘Developing a rapid and precise method for trace element analysis in geothermal water is crucial due to its high total dissolved solids and salinity,which can impact element determination.In this study,we optimized the determination of ferrum,manganese,strontium and barium in geothermal water samples collected from different regions.A matrix matching method was established for accurate quantification using Inductively Coupled Plasma Optical Emission Spectroscopy(ICP-OES).Instrumental conditions and experimental parameters were optimized,and the influence of storage medium and storage duration on measurement accuracy were evaluated.The results demonstrated that storing geothermal water samples in 1%nitric acid had no significant impact on measurement results over an eight-week period.Calibration curve correlation coefficients exceeded 0.9998 for all target elements.The detection limits of this method ranged from 0.0002 mg/L to 0.0031 mg/L,with Relative Standard Deviations(RSD)were 0.07%–2.33%,and spike recovery rates were from 96.8%to 103.2%.The obtained data were consistent with results from the standard addition method and dilution method,demonstrating the reliability of this approach.This method offers low detection limits,high precision and excellent recovery rate,providing a robust reference for the accurate determination of ferrum,manganese,strontium and barium in geothermal water,thereby laying a solid foundation for the development and utilization of geothermal resources.
基金supported by the National Basic Research Program(973)of China(No.2011CB403401)the National Natural Science Foundation of China(No.41105088,41275141)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR2011DQ001)the State Key Laboratory for Coal Resources and Safe Mining(No.SKLCRSM11KFB03)
文摘Trace metals in PM2.5 were measured at one industrial site and one urban site during September, 2010 in Ji＇nan, eastern China. Individual aerosol particles and PM2.5 samples were collected concurrently at both sites. Mass concentrations of eleven trace metals （i.e., Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, and Pb） and one metalloid （i.e., As） were measured by inductively coupled plasma atomic emission spectroscopy （ICP-AES）. The result shows that mass concentrations of PM2.5 （130μg/m3） and trace metals （4.03 μg/m3） at the industrial site were 1.3 times and 1.7 times higher than those at the urban site, respectively, indicating that industrial activities nearby the city can emit trace metals into the surrounding atmosphere. Fe concentrations were the highest among all the measured trace metals at both sites, with concentrations of 1.04 ixg/m 3 at the urban site and 2.41 Itg/m3 at the industrial site, respectively. In addition, Pb showed the highest enrichment factors at both sites, suggesting the emissions from anthropogenic activities existed around the city. Correlation coefficient analysis and principal component analysis revealed that Cu, Fe, Mn, Pb, and Zn were originated from vehicular traffic and industrial emissions at both sites; As, Cr, and part of Pb from coal-fired power plant; Ba and Ti from natural soil. Based on the transmission electron microscopy analysis, we found that most of the trace metals were internally mixed with secondary sulfate/organic particles. These internally mixed trace metals in the urban air may have different toxic abilities compared with externally mixed trace metals.
基金National Defense Basic Research Program (D0620060433)
文摘This article presents a mathematical model of helical end-milling forces through experimental identification of the cutting coefficients and analyzes the changes of comer-milling forces under different conditions. In allusion to the corner-milling process, the relationship between working parameters and the comer coordinates is investigated by way of combination of tool tracing and cutting geometrodynamics. The milling parameters are optimized by changing the coordinates of tool center and working parameters without altering curing forces. By applying the optimized parameters to milling practice, a comparison is made to show the improved product quality. Based on these optimized parameters, a finite element method （FEM） program is used to compute deformation values of a workpiece＇s comer, which evidences few effects that optimized parameters can exert on the comer deformation.
文摘Deformation behavior of 1 Al containing Mg alloy has been investigated in the present study.After annealing,the Mg-1 Al alloy shows a typical basal texture.When compared to the pure Mg having a similar texture and grain size,the Mg-1 Al alloy shows much higher strength and larger elongation.Slip trace analyses of the tensile strained specimens show that non-basal slips such as pyramidal I and II slips can be easily activated at an early stage of deformation in the Mg-1 Al alloy and the grains in the Mg-1 Al alloy are seen to accommodate a larger degree of deformation than those in the pure Mg at a given strain.With increasing tensile strain,however,there is a strain localization along the initially formed slip lines of non-basal slips,forming surface steps without activating multiple slip lines.
基金funding from the Madrid region under programme S2018/NMT4381-MAT4.0-CM projectFunding from projects PID2019111285RB-I00 and PID2020-118626RB-I00 awarded by the Spanish Ministry of Science, Innovation and Universitiesfinancial support from the China Scholarship Council (Grant no 201706050154)
文摘This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in Mg-Zn and Mg-Al alloys. With that aim, four solid solution Mg-Zn and Mg-Al binary alloy ingots containing 1 and 2 wt.% solute atoms were subjected to hot rolling and subsequent annealing to generate polycrystals with similar average grain size and basal-type texture for each composition. The activity of the different slip systems after tensile testing at 150°C and at 250°C was evaluated in pure Mg and in the alloys by EBSD-assisted slip trace analysis. In addition, segregation of Zn and Al atoms at grain boundaries during the thermo-mechanical processing was characterized by HAADF-STEM and EDX. It was found that while the addition of Al and Zn atoms to pure Mg does not lead to major changes in the mechanical strength at the investigated temperatures, it does enhance ductility significantly, especially at 250℃. Our results show that this increase in ductility cannot be attributed to a higher activation of non-basal systems in the alloys, as reported earlier, as the incidence of non-basal systems is indeed considerably higher in pure Mg. This work suggests, on the contrary, that the ductility increase may be attributed to the presence of a more homogenous basal activity in the alloys due to a lower degree of orientation clustering, to grain boundary solute segregation, and to a higher slip diffusivity at grain interiors.
文摘In the determination of trace yttrium (Y) in an ytterbium (Yb) matrix byinductively coupled plasma atomic emission spectrometry (ICP-AES), the most prominent line ofyttrium, Y 371.030 nm line, suffers from strong interference due to an emission line of ytterbium.In mis work, a method based on wavelet transform was proposed for the spectral interferencecorrection. Haar wavelet was selected as the mother wavelet. The discrete detail after the thirddecomposition, D3, was chosen for quantitative analysis based on the consideration of bothseparation degree and peak height. The linear correlation coefficient between the height of the leftpositive peak in D3 and the concentration of Y was calculated to be 0.9926. Six synthetic sampleswere analyzed, and the recovery for yttrium varied from 96.3 percent to 110.0 percent. The amountsof yttrium in three ytterbium metal samples were determined by the proposed approach with an averagerelative standard deviation (RSD) of 2.5 percent, and the detection limit for yttrium was 0.016percent. This novel correction technique is fast and convenient, since neither complicated modelassumption nor time-consuming iteration is required. Furthermore, it is not affected by thewavelength drift inherent in monochromators that will severely reduce the accuracy of resultsobtained by some chemometric methods.
基金the financial support received from the National Natural Science Foundation of China (No. 21702193)China Academy of Engineering Physics (Nos. TP03201601, TP02201711 and JMJJ20190101)。
文摘Extensive application of nuclear energy has caused widespread environmental uranium contamination.New detection approaches without complicated sample pretreatment and precision instruments are in demand for on-site and in-time determination of uranyl ions in environmental monitoring, especially in an emergency situation. In this work, a simple and effective fluorescent sensor(Z)-N’-hydroxy-4-(1,2,2-triphenylvinyl)benzimidamide(TPE-A) with aggregation-induced emission(AIE) character was established and studied. It could realize to detect UO_(2)2+via quenching the fluorescence of its aggregation-induced emission, with good selectivity and sensitivity. Such strategy shows a wide linear range from 5.0 × 10^(-8)mol/L to 4.5 × 10^(-7)mol/L(R^(2)= 0.9988) with exceptional sensitivity reaching 4.7 × 10^(-9)mol/L, which is far below the limit for uranium in drinking water(30 μg/L, ca. 1.1 × 10-7mol/L) stipulated by the WHO.A response time less than four minutes make it rapid for uranyl ion measurement. It was applied for detection of uranyl ion in spiked river water samples with recoveries in the range of 98.7%-104.0%, comparable to those obtained by ICP-MS. With the advantages of portable apparatus, rapid detection process and high sensitivity, TPE-A can serve as a promising fluorescent sensor for the detection of UO_(2)2+in environmental water samples.
基金the National Key R&D Program of China(No.2017YFA0204403)the National Natural Science Foundation of China(Nos.51971112 and51225102)+2 种基金the Fundamental Research Funds for the Central Universities(No.30919011405)X.Chen would like to acknowledge the finan-cial support from the National Natural Science Foundation of China(Nos.52001165 and 51931003)the Natural Science Foundation of Jiangsu Province,China(No.BK20200475),and the Fundamen-tal Research Funds for the Central Universities(No.30921011215).
文摘Although tension-compression(T-C)asymmetry in yield strength was rarely documented in coarse-grained face centered cubic(FCC)metals as critical resolved shear stress(CRSS)for dislocation slip differs little between tension and compression,the T-C asymmetry in strength,i.e.,higher strength when loaded in compression than in tension,was reported in some FCC high entropy alloys(HEAs)due to twinning and phase transitions activated at high strain regimes in compression.In this paper,we demonstrate a reversed and atypical tension-compression asymmetry(tensile strength markedly exceeds compressive strength)in a non-equiatomic FCC Ni_(2)CoFeV_(0.5)Mo_(0.2) medium entropy alloy(MEA)under dynamic loading,wherein dislocation slip governs dynamic deformation without twins or phase transitions.The asymme-try can be primarily interpreted as higher CRSS and more hard slip modes(lower average Schmid factor)activated in grains under dynamic tension than compression.Besides,larger strain rate sensitivity in dy-namic tension overwhelmingly contributes to the higher flow stress,thanks to the occurrence of more immobile Lomer-locks,narrower spacing of planar slip bands and higher dislocation density.This finding may provide some insights into designing MEAs/HEAs with desired properties under extreme conditions such as blast,impact and crash.
文摘A Nicolet-200SXV FT-IR spectrometer combined with an exciting light set-up has been applied to determine the shallow impurity concentration in detector-grade silicon. The detection sensitivity of boron concentration is high up to 7.8 × 10-12. The calibration curve of boron concentration in high-purity silicon has been obtained, from which the experimental value of calibration factor of boron concentration in silicon is demonstrated to be 1.15 × 1013 cm-1.
