Precision mapping the topological bands of 2D spin-orbit coupling with microwave spin-injection spectroscopy

To investigate the band structure is one of the key approaches to study the fundamental properties of a novel material.We report here the precision band mapping of a 2-dimensional(2D) spin-orbit(SO) coupling in an optical lattice.By applying the microwave spin-injection spectroscopy, the band structure and spin-polarization distribution are achieved simultaneously.The band topology is also addressed with observing the band gap close and re-open at the Dirac points.Furthermore, the lattice depth and the Raman coupling strength are precisely calibrated with relative errors in the order of 10^(-3).Our approach could also be applied for exploring the exotic topological phases with even higher dimensional system.

Determination of Lead in Lime-preserved Egg by Microwave Digestion and Flame Atomic Absorption Spectroscopy

[Objectives] To establish a method for determining the lead content in lime-preserved eggs, to provide a theoretical basis for the quality control of production enterprises and the sampling and testing of supervision departments. [Methods] The lead content in lime-preserved eggs was measured by the microwave digestion and flame atomic absorption spectroscopy. [Results] The method had a correlation coefficient of r2=0.998 in the injection concentration range of 0-4 mg/L. The detection limit of the method was 0.008 2 mg/kg. In the range of 0.2 to 1.0 mg/kg addition concentration, the recovery rate of the method was 92.5%-108.0%, and the relative standard deviation(RSD) was <5%. [Conclusions] This method is accurate and reliable, simple and efficient, and is suitable for the detection of lead in lime-preserved eggs.

Comparison Between Conventional Convective Heating and Microwave Heating: An FTIR Spectroscopy Study of the Effects of Microwave Oven Cooking of Bovine Breast Meat

The effects of microwave energy and conventional convective heating on bovine meat were studied in the mid-infrared region by FTIR spectroscopy, to highlight the differences between the two cooking methods. Samples of 100 g of bovine breast meat were cooked using three treatments: heating in a conventional electric oven at the temperature of 165°C for 16 min, heating in a microwave oven at 800 W for 95 sec, and heating in the same microwave oven at 650 W for 160 sec. Significant decreases in intensity of vibration bands of CH2 methylene group at 1921 and 1853 cm-1 and of the carbonyl band at 1742 cm-1 were observed after microwave heating with respect to heating in a conventional oven, showing that Maillard reaction occurs partially using microwave oven. Spectral analysis in the amide I region after microwave cooking at 800 W for 95 sec showed that an increase in intensity occurred in the region from 1665 to 1690 cm-1 which can be attributed to β-turns, characteristic of disorder processes in the protein. Further analysis after microwave cooking at 650 W for 160 sec evidenced major increase in intensity of β-turns content and the appearance of significant increases of β-sheet component at 1635 cm-1 and 1695 cm-1 that can be attributed to aggregated β-sheets structures.

Quantitative Determination of Density of Ground State Atomic Oxygen from Both TALIF and Emission Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave （MW） resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence （TALIF） using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy （OES）. In this case, we compared the spectra intensities of a specific atomic oxygen line （844 nm） and the closest wavelength xenon line （823 nm）. The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon （1% Xe） of this chemically inert gas inside the air while a further small quantity of H2 （2~） is also added in the mixture in order to collect OH（A- X） and NH（A-X） spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09× 1017＋ 0.2×1017 cm-3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×101T cm-3.

Mossbauer spectroscopy studies on the particle size distribution effect of Fe–B–P amorphous alloy on the microwave absorption properties

An Fe-based nanocrystalline alloy powder is important for application in microwave absorption,and the particle size has a critical impact on the electromagnetic microwave parameters.Therefore,it is necessary to study further the effects of the particle size on such parameters and improve the microwave absorption performance of Febased nanocrystalline powers.In this study,Fe-B-P particles were prepared through a synthetic approach consisting of an aqueous chemical reduction and a ball milling treatment.We investigated the effects of ball milling on the microstructure and electromagnetic properties of Fe-B-P particles.The experimental results indicate that the Fe-B-P particles synthesized through an aqueous chemical reduction are amorphous spheres.Fe-B-P particles with an original particle size of 200-1200 nm can be milled into an irregular shape with the size reduced to\500 nm after 0.5 h of ball milling,and subsequently,the particles become smaller with increases in the milling time,with traces of Fe2O3 generated on the particle surface.The results of the Mo¨ssbauer spectra show that a portion of the small particles demonstrate a superparamagnetic property.The volume proportions of the superparamagnetic component increase from 13.1 to 15.8%as the treatment time increases.We measured the permittivity and permeability spectra of Fe-B-P particles within the frequency range of 2-18 GHz.The reflection loss(RL)is-10 dB for an absorber thickness of 1.7-5.0 mm.The RL is-20 dB for an absorber thickness of 1.9-2.7 mm.The microwave absorption properties of samples with the same thickness are improved with an increase in the treatment time and are shifted to a higher frequency,which will broaden the bandwidth of the absorption as well.

TRACKING PYRITIC SULFUR DURING THE MICROWAVE- CHEMICAL DESULFURIZATION OF COAL USING MOSSBAUER SPECTROSCOPY

The transformations of pyrite in coal during the microwave-chemical treatment for desulfurization of coal was studied with Mossbauer spectroscopy of Fe. The results for phase analyses show that the selective dielectric heating by microwave energy can give rise to the thermal decomposition of pyrite FeS2 in coal to new phases, pyrrhotite Fe1-xS (0【x≤0.125) and troilite FeS which can be dissolved in dilute HC1 solution. Therefore the microwave irradiation combined with the acid washing treatment will be an effective method of desulfurization of coal.

Tunable off-resonant Rydberg microwave frequency comb spectroscopy based on metawaveguide coupled Rydberg atoms

Studying Rydberg microwave frequency comb(MFC)spectroscopy helps increase the working bandwidth of the Rydberg receiver.This Letter demonstrates off-resonant Rydberg MFC spectroscopy in a meta-waveguide-coupled Rydberg atomic system.An off-resonant MFC field couples with the Rydberg atoms through a meta-waveguide.The system can receive the microwave field in the working band from 0.5 GHz to 13.5 GHz,and the MFC spectroscopy covers a span of 36 MHz at three different arbitrarily-chosen frequencies of 2 GHz,3 GHz,and 5.8 GHz.The MFC spectrum that covers a wide range of 125 MHz is also verified.This work is significant for tunable wide-band instant microwave signal detection in the Rydberg atomic system,which is useful in microwave frequency metrology,communication,and radar.

Microwave CVD Thick Diamond Film Synthesis Using CH4/H2/H2O Gas Mixtures

Thick diamond films with a thickness of up to 1.2 mm and a area of 20 cm^2 have been grown in a homemade 5 kW microwave plasma chemical vapor deposition （MPCVD） reactor using CH4/H2/H2O gas mixtures. The growth rate, radial profiles of the film thickness, diamond morphology and quality were evaluated with a range of parameters such as the substrate temperature of 700℃ to 1100℃, the fed gas composition CH4/H2 = 3.0%, H2O/H2 = 0.0%,-2.4%. They were characterized by scanning electron microscopy and Raman spectroscopy. Translucent diamond wafers have been produced without any sign of non-diamond carbon phases, Raman peak as narrow as 4.1 cm^-1. An interesting type of diamond growth instability under certain deposition conditions was observed in a form of accelerated growth of selected diamond crystallites of a very big lateral size, about 1 mm, and of a better structure compared to the rest of the film.

AN INVESTIGATION ON MICROWAVE DYEING OF COTTON FABRICS

This paper deals with the dyeing of cotton fabrics with microwave irradiation.The compara-tive experiments of the microwave dyeing to the conventional dyeing were carried out and themechanism was also discussed.Being subjected to microwave irradiation,the penetration of dyesand chemicals into the fabric can be achieved in a short time with a good color yield.The irradiatedmaterials generate heat via dielectric heating by high frequency electro-magnetic field and as a re-sult,energy saving can be realized.Based on the examination and analysis with X-ray diffraction,IR,SEM,and XPS,the reduction in crystallinity,the formation of active carbonyl groups of freeradicals containing oxygen and the morphological changes in the irradiated cottom fibers werefound.All of these may be believed in favour of the dyeing process.

Growth of 4＂ diameter polycrystailine diamond wafers with high thermal conductivity by 915 MHz microwave plasma chemical vapor deposition

Polycrystalline diamond（PCD） films 100 mm in diameter are grown by 915 MHz microwave plasma chemical vapor deposition（MPCVD） at different process parameters,and their thermal conductivity（TC） is evaluated by a laser flash technique（LFT） in the temperature range of230-380 K.The phase purity and quality of the films are assessed by micro-Raman spectroscopy based on the diamond Raman peak width and the amorphous carbon（a-C） presence in the spectra.Decreasing and increasing dependencies for TC with temperature are found for high and low quality samples,respectively.TC,as high as 1950 ± 230 W m-1 K-1 at room temperature,is measured for the most perfect material.A linear correlation between the TC at room temperature and the fraction of the diamond component in the Raman spectrum for the films is established.

Microwave Synthesis of Silver Nanoparticles Using Different Pentose Carbohydrates as Reducing Agents

A fast, green and readily reproducible microwave-based method for the production of high quality silver nanoparticles （AgNPs） in high yield is presented. Starch is used as a stabilizing agent with few pentose different reducing carbohydrates as D-ribose, D-arabinose and L-arabinose. From the UV-vis peak profile spectra of the solutions of the silver nanoparticles, the authors have investigated the size of the NPs together with the average diameter, shape, and aggregation state of the colloidal AgNPs. TEM measurements and EDX analysis have confirmed the morphology of our AgNPs.

Microwave Synthesis of Au Nanoparticles with the System of AuCl_4-CH_3CH_2OH

The Au nanoparticles has been prepared by microwave high-pressure procedure with alcohol as the reducing agent. The color of colloidal Au nanoparticles is blue-violet. The maximum absorption spectrum of colloidal Au is at 580 nm, and the resonance scattering peak is at 580 nm. Using this method, the colloidal Au of long-time stability can be prepared Simply and quickly.

A Study on the Determination of Copper by Microwave Induced Plasma Atomic Emission Spectrometry (MIP-AES)

The determination of copper by MIP-AES was investigated in detail. Aqueous samples were introduced from an ultrasonic nebulizer and the solvent was removed by a desolvation device before introduction of the aerosol into the MIP. The desolvation system consisted of a condenser associated with a concentrated H2SO4 absorption cell. Various experimental conditions and interferences from easily ionised elements (EIEs) were also studied and some practical samples were analyzed.

Decomposition reaction of phosphate rock under the action of microwave plasma

The decomposition reaction of phosphate rock under the action of microwave plasma was investigated.Phosphate rock and its decomposition products were characterized by x-ray diffraction(XRD),energy disperse spectroscopy(EDS),and chemical analysis.The measurements of electron temperature(T_(e)) and electron density(N_(e)) of plasma plume under atmospheric pressure were carried out using optical emission spectroscopy(OES).The electron temperature(T_(e)) was determined based on the calculation of the relative intensity of the O Ⅱ(301.91 nm) and O Ⅱ(347.49 nm) spectral lines.Correspondingly,electron densities were obtained using the Saha ionization equation which was based on the C Ⅰ(247.86 nm) line and the C Ⅱ(296.62 nm) line under the assumption of local thermodynamic equilibrium(LTE).The relationship between the relative intensity of the active components and the gas output was studied by the spectrometer.Finally the reaction mechanism of the decomposition of the phosphate rock under the action of the atmospheric pressure microwave plasma was proposed.The results showed that with the increase of CO flow and microwave power,the electron temperature and electron density in the plasma show a decreasing and increasing trend.The CO is dissociated into gaseous carbon ions under the action of microwave plasma,and the presence of gaseous carbon ions promotes the decomposition of the phosphate rock.

Physicochemical Characterization and Antimicrobial Properties of Inulin Acetate Obtained by Microwave-Assisted Synthesis

Microwave-assisted irradiation was performed for esterification of chicory inulin with high degree of polymerization with acetic anhydride without a solvent only with a catalyst.The resulting esters were characterized by melting point,hydrophilic-lipophilic balance,thin-layer chromatography,ultraviolet spectroscopy,Fourier transform infrared spectroscopy(FTIR)and nuclear magnetic resonance(NMR)spectroscopy.Inulin acetate demonstrated a high degree of acetylation(2.5-3.0)and presented a white,water-insoluble substance with bitter taste.The FTIR and NMR spectra confirmed esterification and demonstrated the incorporation of hydrophobic residue to the water soluble inulin backbone.Swelling capacity,water holding,oil-holding capacities,the foamability,foam stability and emulsifying properties were also evaluated.Inulin acetate showed promising foam stability 52%for 60 min and formed stable emulsions at concentration 0.2 g/L with 50 and 80%oil phases.Its water holding capacity was lower than the oil holding capacity.In addition to this,for the first time,the antimicrobial potential of inulin acetate was tested against seventeen microorganisms(Gram-positive and Gram-negative bacteria,yeasts and fungi).Inulin acetate(10 mg/ml)inhibited the growth of Bacillus cereus,Escherichia coli ATCC 8739,Salmonella abony,Candida albicans and Penicillium sp.However,inulin acetate demonstrated antimicrobial activity at concentration 1 mg/ml against Listeria monocytogenes 863,Escherichia coli 3398,Candida albicans 8673,Fusarium oxysporum and Aspergillus niger.The current study demonstrated the applications of“green”synthesized inulin acetate as a foaming agent,oil-in-water emulsion stabilizer and antimicrobial substance in pharmaceutical,agricultural and cosmetic preparations.

Microwave Induced Plasma Source for Analytical Applications： Experimental and Simulation Study

In this work, experiment investigations and simulation studies of a waveguide-based microwave plasma source operated at 2.45 GHz in atmospheric pressure helium gas are presented. The plasma source has been designed in conjunction with a gas spectrograph as a speciation analysis tool. Emitted He spectra are observed for gas flow rates between （0.2-1） L/min and microwave power in the range （15-150） W. The results obtained demonstrate maximum excitation temperature of about 3800 K and gas temperature of about 2000 K. Mixtures containing small amounts of mercury atoms are considered and the resonant emission of Hg atoms at 253.56 nm is detected. The spectroscopic measurements are completed with a collisional radiative model delivering the electron density and temperature, the amplitude of the electric microwave field, and the population of the excited atomic states for a given absorbed power and gas temperature, The electromagnetic field distribution in the plasma source is obtained by solving Maxwell＇s equations. Electric field strength of several 10^5 V/m is obtained that agrees well with the results of the collisional radiative model. The calculated and measured line intensity ratios of He spectral lines agree within 300/0-40%.

MOSSBAUER ANALYSIS ON THE MICROWAVE-MAGNETIC DESULFURIZATION OF RAW COAL

The selective dielectric heating of microwave energy to convert a portion of each pyrite particle to moderately magnetic pyrrhotite has been suggested to enhance the magnetic separation of inorganic sulfur from coal. The results for Mossbauer analyses show that the considerable amount of pyrrhotite produced during microwave irradiation, carrying with it some of non--magnetic pyrite (unconverted), ferrous sulfate, and troilite, is completely removed from coal after magnetic separation. The opthoum desulfurization efficiency can be attsined by appropriately controlling the irradiation time to maximize the amount of pyrrhotite formed pyrite decomposition.Excessive irradiation would be disadvantageous for improving magnetic separation due to the further decomposition of pyrrhotite to antiferromagnetic troilite.

Synthesis of LaF_3 superfine powder by microwave heating method

LaF3 superfine powder was synthesized from La（CH3COO）3 and NH4F by micro wave heating method,using ethanol or pure water as dispersants respectively. Th e results of XRD and SEM indicate that the superfine powder has high purity,reg ular particle shape and narrow distribution of granularity. The granularity of t he best sample is in the range of 100200 nm.The influence of different dispersants on the crystal degree and microstructure was discussed. After the su perfine powder was formed into a slice at pressure of 2560 MPa,its ele ctrochemical impedance spectroscopy was tested by electrochemical impedance spec troscopy（EIS） measurement. The result shows that the grain refining of LaF3 po wder increases its ionic conductivity. Compared with traditional preparation met hods of LaF3 powder,the advantages of microwave heating method were summarize d.

原子吸收光谱法测定土壤中铜、锌、镉含量

文章研究了原子吸收光谱法测定土壤中铜、锌、镉含量的方法,优化了仪器测定条件、微波消解试剂等。铜的浓度在0.05~0.4μg·mL^(-1)范围内线性相关系数r=0.99930,锌的浓度在0.02~0.8μg·mL^(-1)范围内线性相关系数r=0.99940,镉的浓度在0.2~2.4μg·L^(-1)范围内线性相关系数r=0.99840。加标回收率在95.3%~104.6%之间,方法的相对标准偏差(n=6)在0.87%~5.91%之间。通过对某农田8个土壤样品铜、锌、镉含量检测,建立了良好的方法,实验结果表明,该方法准确度高,精密度好,为监管部门提供了一定的参考。

微波消解-电感耦合等离子体发射光谱法快速测定盐渍土中二氧化硅

建立微波消解-电感耦合等离子体发射光谱(ICP-OES)法快速测定盐渍土中二氧化硅含量的方法。称取0.1000 g土壤样品,加入1 mL浓盐酸,1 mL浓硝酸和2 mL氢氟酸,微波消解120 min,最高消解温度为180℃,样品溶液采用ICP-OES法进行测定,以标准工作曲线法定量。硅元素的质量浓度在0~100 mg/L范围内与光谱强度线性关系良好,相关系数为0.9998,二氧化硅的检出限为0.045 mg/kg。利用该方法对3个土壤样品进行测定,二氧化硅测定结果的相对标准偏差为0.354%~0.608%(n=6),对土壤成分分析标准物质GBW 07408、GBW 07447和GBW 07452进行测定,测定值均在标准值不确定度范围内。该方法可快速测定盐渍土中二氧化硅含量。