Analysis of trace elements in air particulate matters by non-suppressed ion chromatography

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.

SPECTROPHOTOMETRIC ANALYSIS OF MIXTURES OF TRACE METAL BY DOUBLE-SYSTEM AND MULTIVARIATE CALIRRATION

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.

Analysis on Serum Trace Element Levels of Echinococciasis Patients in Garze Tibetan Autonomous Prefecture in Sichuan,China,2011

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.

Effect of 1Al addition on deformation behavior of Mg

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.

Determination of micro yttrium in an ytterbium matrix by inductively coupled plasma atomic emission spectrometry and wavelet transform

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.

The relation between ductility at high temperature and solid solution in Mg alloys

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.

Determination of Shallow Impurity Concentration in Detector-grade Silicon by FT-IR Spectroscopy at 4.2K

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.

Determination of Trace Nickel in Manganese Dioxide by Differential Pulse Polarography

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.

Preparation and Characterization of Gold Thin Film Electrode Modified by Microbe

A novel method based on microbe modification has been employed to prepare gold thin film electrode. The preparation method is simple and the electrode obtained is stable and very sensitive in determining heavy metal ions. The quantitation limit of Cu2+ is 0.05 ng/mL.

Determination of Sodium Pentachlorophenoxide Residues in Animal-derived Foods by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS)

[Objectives]This study was conducted to establish an ultra-high performance liquid chromatography-tandem mass spectrometry for the rapid extraction of sodium pentachlorophenoxide from animal-derived food.[Methods]The samples were extracted with an acetonitrile water solution(8∶2),0.1 mol/L hydrochloric acid and a purification extraction bag with shaking.Centrifugation was performed to obtain supernatants,which were added to purification tubes containing PSA and C_(18) for purification,and then filtered with membranes for determination.Each test solution was separated by a ZORBAX Eclipse plus C_(18) column with acetonitrile and 5 mmol/L ammonium acetate as mobile phases,and determined with electrospray ionization and multiple reaction monitoring.[Results]The method had good linearity in the concentration range of 1.0-50 ng/ml,and the correlation coefficient was 0.9997.The limit of detection was 0.25μg/kg and the limit of quantification was 0.75μg/kg.The recovery was between 87.4%and 112.5%,and the RSD%was between 0.5%and 10.0%.[Conclusions]The method has simple operation and high sensitivity,and is suitable for trace detection of sodium pentachlorophenoxide in large quantities of animal-derived food.

Trace Analysis of Anions in Perfluorodecalin by Green Liquid-Liquid Extraction Combined with Ion Chromatography

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.

Chemical characteristics of trace metals in PM10 and their concentrated weighted trajectory analysis at Central Delhi,India

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.

TRAP:trace runtime analysis of properties

We present a method and a tool for the verification of causal and temporal properties for embedded systems.We analyze trace streams resulting from the execution of virtual prototypes that combine simulated hardware and embedded software.The main originality lies in the use of logical clocks to abstract away irrelevant information from the trace.We propose a model-based approach that relies on domain specific languages(DSL).A first DSL,called TISL(trace item specification language),captures the relevant data structures.A second DSL,called STML(simulation trace mapping language),abstracts the simulation raw data into logical clocks,abstracting simulation data into relevant observation probes and thus reducing the trace streams size.The third DSL,called TPSL,defines a set of behavioral patterns that include widely used temporal properties.This is meant for users who are not familiar with temporal logics.Each pattern is transformed into an automata.All the automata are executed concurrently and each one raises an error if and when the related TPSL property is violated.The contribution is the integration of this pattern-based property specification language into the SimSoC virtual prototyping framework without requiring to recompile all the simulation models when the properties evolve.We illustrate our approach with experiments that show the possibility to use multi-core platforms to parallelize the simulation and verification processes,thus reducing the verification time.

Accuracy and analysis of long-radius measurement with long trace profiler

The long trace profiler （LTP） is proposed to measure radius of curvature （R） and surface figure of a longradius spherical surface in an optical shop. Equipped with a motorized rotary stage and a two-dimensional tilt stage, the LTP scans the full aperture and calculates the absolute radius of curvature of each scanning line based on the least square method. Nonlinear error and manufacture error difference between center and the edge are obtained by comparing R results. The R-limit is validated and expressed as D/R, where D is the aperture of the mirror under test. A full-aperture three-dimensional figure is also reconstructed based on triangle interpolation.

Self-assembly at Liquid-Liquid Interface: A New SERS Substrate for Analytical Sensing

As a highly powerful and sensitive tool,surface enhanced Raman scattering(SERs)has attracted extensive attention in quantification analysis.However,the strong dependence of SERS signal on the detailed local nanostructure makes quantitative SERS analysis suffer from difficulties in controlling the uniformity of nanoscale hot spots and the inefficiency of placing the targeted molecules in prefabricated hot spots.

Sequence-based Functional Metagenomics Reveals Novel Natural Diversity of Functional CopA in Environmental Microbiomes

Exploring the natural diversity of functional genes/proteins from environmental DNA in high throughput remains challenging.In this study,we developed a sequence-based functional metagenomics procedure for mining the diversity of copper(Cu)resistance gene copA in global microbiomes,by combining the metagenomic assembly technology,local BLAST,evolutionary trace analysis(ETA),chemical synthesis,and conventional functional genomics.In total,87 metagenomes were collected from a public database and subjected to copA detection,resulting in 93,899 hits.Manual curation of 1214 hits of high confidence led to the retrieval of 517 unique CopA candidates,which were further subjected to ETA.Eventually,175 novel copA sequences of high quality were discovered.Phylogenetic analysis showed that almost all these putative CopA proteins were distantly related to known CopA proteins,with 55 sequences from totally unknown species.Ten novel and three known copA genes were chemically synthesized for further functional genomic tests using the Cu-sensitive Escherichia coli(DcopA).The growth test and Cu uptake determination showed that five novel clones had positive effects on host Cu resistance and uptake.One recombinant harboring copA-like 15(copAL15)successfully restored Cu resistance of the host with a substantially enhanced Cu uptake.Two novel copA genes were fused with the gfp gene and expressed in E.coli for microscopic observation.Imaging results showed that they were successfully expressed and their proteins were localized to the membrane.The results here greatly expand the diversity of known CopA proteins,and the sequence-based procedure developed overcomes biases in length,screening methods,and abundance of conventional functional metagenomics.

A simple fluorescent sensor for highly sensitive detection of UO_(2)2+

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.

Dislocation me diate d dynamic tension-compression asymmetry of a Ni_(2)CoFeV_(0.5)Mo_(0.2) medium entropy alloy

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.

Direct Analysis of Whole Blood by a Disposable Monolithic Column Mass Spectrometry Analysis Kit

A monolithic column-based mass spectrometry(MS)analysis kit was prepared for whole blood analysis with MS.The kit is disposable and can be used for purification,storage,transportation and direct analysis of whole blood.The kit mainly consists of a capillary for quantitative microsampling,a cation exchange monolithic column for purification and storage,and a syringe for loading sample.This kit is very friendly to various users that one can easily siphon the blood in the kit followed by rapid clean-up.We established a quantitative method using the kit with a limit detection as low as 0.33 nmol/L,and achieved more than five orders of magnitude enhancement in sensitivity compared to direct nanoelectrospray ionization MS analysis.The column can avoid analyte exposure to environment,which helps the storage of the sample for laboratory analysis.The relative standard deviation of immediate blood analysis and storage blood analysis within 10 d was less than 10%.This method has been successfully applied to the quantitative analysis of procainamide hydrochloride in 2μL rat blood.These results indicate that this disposable kit does have the potential to achieve highly sensitive quantitative MS analysis in biological samples,which is expected to become a cost-effective and powerful tool for in vitro diagnostics.

Corner-milling of Thin Walled Cavities on Aeronautical Components

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.