• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Matrix effect suppressing in the element analysis of soils by laser-induced breakdown spectroscopy with acoustic correction

    2023-12-18 03:54:50ZhiquanHE何智權(quán)LiLIU劉莉ZhongqiHAO郝中騏ZhishuaiXU徐智帥QiWANG王奇YingLU盧穎ZiyiZHAO趙梓屹JiulinSHI史久林andXingdaoHE何興道
    Plasma Science and Technology 2023年12期
    關(guān)鍵詞:趙梓劉莉

    Zhiquan HE (何智權(quán)) ,Li LIU (劉莉),2 ,Zhongqi HAO (郝中騏),2,3,* ,Zhishuai XU (徐智帥) ,Qi WANG (王奇) ,Ying LU (盧穎) ,Ziyi ZHAO (趙梓屹),Jiulin SHI (史久林),2,3 and Xingdao HE (何興道),2,3

    1 Key Laboratory of Opto-electronic Information Science and Technology of Jiangxi Province,Nanchang Hangkong University,Nanchang 330063,People’s Republic of China

    2 Jiangxi Engineering Laboratory for Optoelectronics Testing Technology,Nanchang Hangkong University,Nanchang 330063,People’s Republic of China

    3 Key Laboratory of Nondestructive Testing (Nanchang Hangkong University),Ministry of Education,Nanchang 330063,People’s Republic of China

    Abstract Laser-induced breakdown spectroscopy (LIBS) has been used for soil analysis,but its measurement accuracy is often influenced by matrix effects of different kinds of soils.In this work,a method for matrix effect suppressing was developed using laser-induced plasma acoustic signals to correct the original spectrum,thereby improving the analysis accuracy of the soil elements.A good linear relationship was investigated firstly between the original spectral intensity and the acoustic signals.The relative standard deviations(RSDs)of Mg,Ca,Sr,and Ba elements were then calculated for both the original spectrum and the spectrum with the acoustic correction,and the RSDs were significantly reduced with the acoustic correction.Finally,calibration curves of Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm and Ba II 455.403 nm were established to assess the analytical performance of the proposed acoustic correction method.The values of the determination coefficient(R2)of the calibration curves for Mg,Ca,Sr,and Ba elements,corrected by the acoustic amplitude,are improved from 0.9845,0.9588,0.6165,and 0.6490 to 0.9876,0.9677,0.8768,and 0.8209,respectively.The values of R2 of the calibration curves corrected by the acoustic energy are further improved to 0.9917,0.9827,0.8835,and 0.8694,respectively.These results suggest that the matrix effect of LIBS on soils can be clearly improved by using acoustic correction,and acoustic energy correction works more efficiently than acoustic amplitude correction.This work provides a simple and efficient method for correcting matrix effects in the element analysis of soils by acoustic signals.

    Keywords: laser-induced breakdown spectroscopy,acoustic correction,matrix effect,calibration curve,relative standard deviation

    1.Introduction

    It is of great significance to measure quantitatively the concentration of various elements in soil in different areas,such as agriculture,environmental protection,geological exploration and so on [1].Laser-induced breakdown spectroscopy(LIBS) is an atomic emission spectroscopy technique based on the interaction between high-power lasers and matter,which generates a transient plasma and analyzes the composition information of a sample through the emission spectra of the atoms or ions splashed from the plasma[2].Compared to traditional chemical analysis methods,LIBS has some unique advantages,such as rapid measurement,multi-elemental detection,and little or no sample preparation [3].Due to the aforementioned advantages,LIBS has become an attractive technique for soil elements analysis in the past decade [4-7],where the concentration of metal element(such as Mg,Ca,Sr and Ba) is of great importance for geochemical studies and mineral resources.

    The measurement of soil elements by LIBS is heavily influenced by matrix effects,which arise from the complex chemical composition and structure of different soils [8].Matrix effects originate from changes in the physical or chemical properties of the sample matrix that affect the measurement signal.Consequently,when measuring a certain element in samples with different matrices,even if the content of the measured element is the same,different measurement signals will be obtained [9].Therefore,it is critical to suppress the impact of matrix effects for the element analysis of soils by LIBS.

    The main method to eliminate matrix effects is data processing,where the original spectral intensity after data processing can more accurately reflect the concentration information of the measured element in the sample [10].Internal standard analysis [11-13] is a common data processing method.The internal standard method involves selecting an element from the sample as the internal standard element,which can be artificially added to the sample or can be a main element with similar content in various samples.However,since a diverse range of the elements in soil,it is difficult to find a main element with similar content in the soil,making the application of the internal standard method less effective in improving matrix effects in soil analysis by LIBS [14].In addition,normalization is also a common data processing method in LIBS,which utilizes the correlation between a reference signal and the original spectral intensity to suppress the effects of matrix effects and experimental parameter fluctuations,such as using the electric current [15,16],ablated mass [17,18],and plasma emission images [19-21]for normalization.

    For external signal normalization,the acoustic wave generated by the plasma has been proven to be an effective reference signal[22].During the process of laser ablation,the expansion of material particles leads to collisions between the ablated particles and ambient gas molecules,generating plasma acoustic waves [23].The acoustic waves exhibit a favorable linear correlation with ablation mass and can thus be utilized to normalize spectral signals,reducing the impact of pulse-to-pulse ablation mass fluctuations and inter-sample variations in ablation mass [24-27].

    Popov et al investigated the effect of compression force,moisture,and total content of easily ionized elements on plasma parameters and intensity of analytical signals for different types of geomaterials [28].Labutin et al proposed the first and the eighth minima of the OA signal and an AE signal originating from the solid sample matrix(aluminum)at k=396.1 nm as reference signals [29].Li et al proposed adaptive weighted normalization-LWNet (AWN-LWNet)framework to reduce the matrix effect in two soil types [30].Sun et al used machine learning algorithms,specifically a back-propagation neural network,to develop a multivariate model that incorporates the concept of generalized spectrum to explicitly include information about the soil matrix [31].Wang et al used external normalization strategies based on plasma acoustic signals,plasma images,and the acousticimage combination to improve the stability of underwater LIBS for oceanic applications [32].

    Analyzing the alkali-earth metal elements (Mg,Ca,Sr,and Ba) provides important information about soil quality,plant growth and development,and ecological risks.These elements affect soil pH,plant nutrition,and quality,and their analysis can assist in adjusting fertilization techniques and improving crop yields.In addition,they can provide insight into soil suitability for certain plants and the potential ecological threats posed by the elements [33].These elements in soils can also be easily detected by LIBS systems.Therefore,the improvement effect of using audio correction on the measured concentrations of magnesium,calcium,strontium and barium elements in soil by LIBS will be investigated.

    To our knowledge,there has been very little investigation into the use of acoustic correction for suppressing the matrix effect in soils.In this work,a method for correcting the spectrum using acoustic signals obtained from a condenser microphone near the induction plasma was proposed.Initially,features of acoustic signals and their relationship to the LIBS spectrum will be presented.The effectiveness of acoustic correction on reducing signal fluctuations and enhancing quantitative analysis will then be assessed.Our focus will be on comparing the results of the calibration curves obtained from the original LIBS signal,the LIBS signal corrected with acoustic amplitude,and the LIBS signal corrected with acoustic energy.

    2.Experimental setup

    Table 1.Concentrations of Mg,Ca,Sr and Ba in the 8 soils samples (wt%).

    Figure 1 shows the experimental setup for the acoustic correction LIBS system.The Nd:YAG laser (Continuum,Precision II)with a wavelength of 532 nm,a frequency of 10 Hz,and a pulse duration of 10 ns is used.The three-channel fiber spectrometer (Avantes,AvaSpec-ULS4096CL-3-EVO) has a maximum resolution of 0.05 nm,the integration time ranges from 1.1 ms to 10 min,and the detectable wavelength range is 200-450 nm.The CCD converts the collected optical signals into electrical signals,and the spectral data is obtained by computer software processing.The microphone (Superlux,ECM999) is a capacitance microphone with a frequency response range of 20-20 kHz and a sensitivity of-43 dBV Pa-1.The acoustic signals detected by the microphone are displayed on an oscilloscope,which can output the acoustic information to the computer.The oscilloscope(Pico,3203D) has a working bandwidth of 50 MHz and a sampling rate of 1 GS s-1.To prevent the sample from being damaged by continuous laser pulses at the same point,the soil sample is placed on a motorized XYZ translation stage.To measure the LIBS spectra and the corresponding acoustic signals simultaneously,the spectrometer collects the spectral data without averaging,and each set of spectral signals is repeated 20 times.The acoustic acquisition system is set to a length of 200 ms per grid (20 acoustic signals are collected per acquisition cycle of 2 s).Each sample is measured six times,and then the acoustic signals corresponding to the spectral signals can be obtained in this way.

    Those samples used in the experiment were national standard plow layer soil samples from eight different provinces in China.The soil samples were air-dried and cleaned of debris,then ball-milled for 4-6 h using a high-alumina ceramic ball mill and sieved through a 20-mesh nylon screen.After mixing,the samples were dried at 105°C for 24 h,and then discharged after being mixed again using the ball mill.

    Figure2.Measured elemental spectrum from GSS-61 soil sample.

    The concentrations of Mg,Ca,Sr and Ba elements in the soil samples are shown in table 1.To prevent splashing of the samples when the laser pulse hits them,the soil powder was pressed into pellets under 16 MPa pressure.Based on the NIST database,Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm were determined as the elemental spectral lines for experimental analysis,the measured elemental spectrum is shown in figure 2.

    Figure3.Variation in intensity and SNR with defocus distance(a),(d),delay time(b),(e),and laser energy(c),(f)for Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm.

    3.Results and discussion

    3.1.Optimization of experimental parameters

    It is necessary to collect both the spectral signal of the laserinduced plasma and its corresponding audio signal for acoustic correction.During the data collection process,various experimental factors may affect the accuracy of the results.For collecting the spectral signal,the factors include defocus distance,delay time,and laser energy.For collecting the audio signal,the factors include laser energy and the acoustic distance which represents the distance from the microphone to the sample.Therefore,it is essential to optimize these five main experimental parameters to obtain the best results for quantitative analysis,which is crucial for meaningful research and analysis.

    To determine a suitable defocus distance,delay time and laser energy for quantitative analysis of Mg,Ca,Sr and Ba elements in soils’ sample,the intensity and signal-to-noise(SNR) of Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm as a function of defocus distance,delay time and laser energy was studied.As shown in figure 3(a),decreasing defocus distance gradually from 1 to-4 mm with a gate width of 1 mm,the intensities increased gradually with the increasing of defocus distance from 1 to-1 mm,whereas the intensities decreased dramatically with the increasing of defocus distance after -1 mm.From figure 3(d),the SNRs have a similar variation rule with intensities.As shown in figures 3(b)and(e),increasing delay time gradually from 0 to 5 μs with a gate width of 1 μs,the intensities decreased gradually with the increasing of defocus distance from 1 to-1 mm,while the SNRs are first increased to 1 μs as the maximum,and then decreased.As shown in figures 3(c)and(f),increasing laser energy gradually from 20 to 80 mJ with a gate width of 10 mJ,the intensities increased with the increasing of laser energy from 20 to 60 mJ,however the intensities decreased gradually with the increasing of laser energy after 60 mJ and figure 3(d) also shows a similar variation rule with intensities.A higher SNR indicates that the environmental background has less of an impact on the experimental results.Therefore,the defocus distance,delay time and laser energy were fixed to-1 mm,1 μs and 60 mJ in this experiment,respectively.

    To determine a suitable laser energy and acoustic distance for audio signal acquisition,the acoustic amplitude as a function of laser energy and acoustic distance was studied.The acoustic intensity as represented by the amplitude of the first acoustic peak is depicted in figure 4(a),with a laser energy range of 40-100 mJ.The results indicate a strong relationship between the acoustic signal and laser energy,as evidenced by the high determination coefficient R2of 0.9760 obtained through quadratic polynomial fitting.This suggests that the acoustic signal is likely to follow a quadratic function in relation to laser energy,rather than a linear function,which could be attributed to the plasma shielding effect observed at high laser energies.Figure 4(b) shows the dependence of the acoustic intensity on the acoustic distance in the range of 20-50 cm.We can also see a very good correlation between the acoustic signal and the acoustic distance.The determination coefficient R2is 0.9885,obtained from a quadratic polynomial fitting.It also indicates that the close acoustic distance may lead to the distorted audio signal.To avoid distortion of the audio signal and to make the audio signal work in the linear area,the laser energy and acoustic distance were fixed to 60 mJ and 40 cm,respectively.The final experimental parameter optimization results are shown in table 2.

    Figure4.Variation in acoustic amplitude with laser energy (a) and acoustic distance (b).

    Figure5.Acoustic signal time-domain feature diagram.

    3.2.Relationship between acoustic signals and spectrum intensity

    The acoustic signal captured through a microphone was shown in figure 5,with two strong signals appearing at the beginning of the signal and about 2 ms after signal generation,respectively (marked in the figure).The first strong acoustic peak is caused by laser-induced optical breakdown,while the formation of the second one may be due to surface collapse of the sample [34].Apart from these two peaks,other peaks are actually caused by continuous reflection of the acoustic signal by the surrounding objects,and do not make sense to the laser breakdown process.In this experiment,the first strong signal(i.e.the first sine wave signal) was extracted,andcharacteristic parameters related to the acoustic signal were extracted to correct the original spectral intensity.

    Table 2.Experimental parameter optimization results.

    For acoustic signals,the first peak value is a suitable reference signal for correction because it varies in amplitude each time,allowing for the extraction of peak values of each signal segment for correction processing [22].Besides,the energy(E)of the first signal segment can also be extracted as a reference signal to discuss its effect on improving the matrix effects.The calculated formula of E is as follows:

    where x(t) is the acoustic signal amplitude varies with time t,t1and t2are the integration times of 100.1 and 100.5 ms.Then,other signal segments were extracted from acoustic signal bands and integrated,respectively.

    Figure 6 shows spectral intensity of Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm as a function of (a) first acoustic peak amplitude and (b) laser energy.The solid lines represent the linear fitting of the data,and the Pearson correlation coefficients r are calculated and shown in each figure.The values of r between the first peak amplitude and the spectral intensity are close to or greater than 0.5 in absolute values,and negatively correlated.This is mainly due to the complex chemical composition of soil,where the amplitude of the acoustic signal generated by laserinduced breakdown plasma correlates with certain specific elements in the soil [35].Higher content of Mg,Ca,Sr,and Ba elements leads to lower acoustic signal amplitude during laser-induced breakdown,which indicates a negative correlation between these elements and acoustic amplitude.Comparison between figures 6(a) and (b) shows a stronger correlation between acoustic energy and spectral line intensity,where the absolute values of r for Mg,Ca,Sr,and Ba elements are increased from 0.4821,0.6087,0.5335,and 0.6490 to 0.5074,0.6319,and 0.7166,respectively.The improvement in correlation is the most significant for Ba element,while the absolute values of r for Ca element decrease contrarily,possibly due to the high content of Ca element in soil samples causing noticeable self-absorption,resulting in less obvious regularities in fitting with acoustic energy [36].

    Figure6.Acoustic amplitude (a) and the acoustic energy (b) vary with the original spectral intensity.

    3.3.Matrix effects suppressing with acoustic correction

    The acoustic correction is a normalization method that uses an audio signal as a reference signal for the characteristic spectral lines of the detected element and is similar to the internal standard method in LIBS analysis [37].When the laser pulse hits the surface of the soil samples,the acquisition of acoustic signals will not be affected by matrix effects,and therefore acoustic signals can be used to correct the original spectral intensity[38].The formulas of acoustic amplitude and energy corrections are as follows:

    where,I0represents the original spectral intensity,A represents the acoustic amplitude,and IArepresents the spectral intensity corrected by acoustic amplitude;E represents the acoustic energy,IErepresents the spectral intensity corrected by acoustic energy.

    Figure7.RSDs of the original spectra line and spectra lines with acoustic amplitude correction and acoustic energy correction (AP:acoustic amplitude;AE: acoustic energy).

    Different correction methods were employed to assess and compare the stability of LIBS signals.Figure 7 shows the relative standard deviations (RSDs) of the spectral intensities of Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm without correction and with acoustic amplitude and energy corrections.The formulas of the RSDs of Mg,Ca,Sr and Ba elements are as follows:

    where,Xiis the data measured by LIBS;n is the measurement time;M refers to the average of this set of data;S is the standard deviation of the measurement precision to be evaluated.

    Figure8.Calibration curves of Mg(a),Ca(b),Sr(c)and Ba(d)obtained with the original spectral intensity,the spectral intensity corrected with acoustic amplitude,the spectral intensity corrected with acoustic energy,and the spectral intensity corrected with internal standard method.

    Each RSD is calculated from 20 replicate spectra.As can be seen from figure 7,after correcting with acoustic amplitude,the RSDs for Mg,Ca,Sr,and Ba elements decreased from 3.26%,3.37%,1.59%,and 2.78% to 3.12%,2.82%,1.38%,and 2.3%,respectively.Furthermore,the RSDs were further reduced to 2.58%,2.76%,1.18%,and 1.96%by using acoustic energy correction.These results suggest that the stability of soils LIBS can be improved by using acoustic correction.Meanwhile,the acoustic energy correction had a better effect on reducing the LIBS signal fluctuation than acoustic amplitude correction.These results are consistent with the conclusion in figure 6 that the spectral line has a higher connection with the acoustic energy than with the acoustic amplitude.

    Finally,calibration curves of Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm were then established to assess the analytical performance of the proposed acoustic correction method.Figure 8 shows four calibration curves: solid for original lines,dotted for lines corrected by acoustic amplitude,dashed for lines corrected by acoustic energy,and double dash for lines corrected by internal standard method.The silicon content in 8 soil samples is similar,so silicon was selected as the internal standard element to correct the original spectra.The error bars correspond to RSDs of 6 sets of data obtained by averaging 20 replicate spectra.R2is the determination coefficient of the calibration curves that represents the degree of correlation between the experimental data and element concentration.The formulas of the R2of the calibration curves are as follows:

    As shown in figure 8,after correction with acoustic amplitude,the values of R2for Mg,Ca,Sr,and Ba elements can be improved from 0.9845,0.9588,0.6165,and 0.6490 to 0.9876,0.9677,0.8768,and 0.8209,respectively.Moreover,after correction with acoustic energy,the values of R2can be further risen to 0.9917,0.9827,0.8835,and 0.8694,respectively.However,after correcting with the internal standard method,although the values of R2of Ca and Ba elements have been improved from 0.9588 and 0.6490 to 0.9591 and 0.8090,the effect is still weaker than that of acoustic correction,and the values of R2for correcting Mg and Sr elements using the internal standard method are decreased from 0.9845 and 0.6165 to 0.9494 and 0.4940.It should be noted that the calibration curves of Ca element were fitted quadratically while the others were fitted linearly.This is due to the self-absorption effects of Ca element,even whose concentration reaches a maximum of 3.91% in these soil samples [39].

    According to the above results,it can be concluded that both acoustic energy correction and acoustic amplitude correction can suppress the matrix effects in soil analysis,and the correction effect is better than that of the internal standard method.These findings are consistent with the conclusions drawn from figure 6,which suggests that the spectral line has a higher correlation with the acoustic energy than with the acoustic amplitude,and from figure 7,which indicates that the use of acoustic energy is more effective in reducing the fluctuation of LIBS signals than acoustic amplitude.From the calibration curves of Sr and Ba elements in figures 8(c)and(d),the original calibration curves have low R2values (less than 0.65),while the values of R2of the calibration curves can be significantly improved after correcting with acoustic signals.It refers that the acoustic correction works very efficiently when the matrix effect has a great effect on the soil analysis by LIBS.

    4.Conclusion

    Serious matrix effects can affect the quantitative analysis accuracy of LIBS.In this work,a method was proposed to suppress the matrix effect by using the acoustic signals to correct the spectrum intensity.The acoustic amplitude and its energy were extracted and fitted with the original spectral intensity,which showed a linear negative correlation between them.In addition,the influence of the correction by using acoustic amplitude and acoustic energy on the RSDs of spectral intensity was studied which showed that acoustic correction can improve the stability of LIBS for soil analysis,and the acoustic energy has a better correction effect.The calibration curves of Mg I 285.213 nm,Ca I 422.673 nm,Sr I 460.733 nm,and Ba II 455.403 nm were then established before and after using acoustic correction.The determination coefficients (R2) were compared to assess the analytical performance of the proposed acoustic correction method.After correction with acoustic amplitude,the values of R2for Mg,Ca,Sr,and Ba elements can be improved from 0.9845,0.9588,0.6165,and 0.6490 to 0.9876,0.9677,0.8768,and 0.8209,respectively.Moreover,after correction with acoustic energy,the values of R2can be further risen to 0.9917,0.9827,0.8835,and 0.8694,respectively.Compared with the internal standard method,the acoustic signal correction has a much better effect on matrix effects.These results suggest that the matrix effect of LIBS on soils can be improved by using acoustic correction,and acoustic energy correction works more efficiently than acoustic peak amplitude correction.This work provides a simple and efficient method for correcting matrix effects in the element analysis of soils by acoustic signals.

    Acknowledgments

    This research was financially supported by National Natural Science Foundation of China (No.12064029),by Jiangxi Provincial Natural Science Foundation (No.20202BABL202024),and by the Open project program of Key Laboratory of Opto-Electronic Information Science and Technology of Jiangxi Province (No.ED202208094).

    猜你喜歡
    趙梓劉莉
    很忙
    模特前妻攜子空降:霸氣“拜金”霸氣愛(ài)
    再生水水質(zhì)安全的研究進(jìn)展
    譜華美樂(lè)章 孕綠苑風(fēng)采
    肖金瑩 吳村禹 劉莉作品
    大眾文藝(2021年13期)2021-07-31 11:04:34
    兔子小棕
    省檔案館開(kāi)展“圓夢(mèng)助學(xué)”活動(dòng)
    陜西檔案(2019年5期)2019-01-09 21:58:02
    《綠色行,迎“全運(yùn)”》
    小刺猬與小傘兵
    無(wú)助母子獲救助
    女子世界(2017年8期)2017-08-07 23:45:39
    亚洲五月婷婷丁香| 天堂网av新在线| 真人一进一出gif抽搐免费| 日本a在线网址| av欧美777| 亚洲精品在线观看二区| 又黄又粗又硬又大视频| 校园春色视频在线观看| 一卡2卡三卡四卡精品乱码亚洲| 成年免费大片在线观看| 操出白浆在线播放| 一级作爱视频免费观看| 99在线视频只有这里精品首页| 男女视频在线观看网站免费| 免费大片18禁| 国产精品av久久久久免费| 久久久久久久精品吃奶| 色精品久久人妻99蜜桃| 真人一进一出gif抽搐免费| 亚洲成人久久爱视频| 久久亚洲真实| 91在线精品国自产拍蜜月 | 亚洲,欧美精品.| 国产高清视频在线观看网站| 久久精品影院6| 国产亚洲欧美在线一区二区| 久久久久久久午夜电影| 亚洲精品美女久久久久99蜜臀| av在线蜜桃| 亚洲成人免费电影在线观看| 日韩人妻高清精品专区| 色在线成人网| 日韩欧美精品v在线| 我的老师免费观看完整版| 手机成人av网站| 国产精品乱码一区二三区的特点| 老熟妇乱子伦视频在线观看| av在线蜜桃| 美女大奶头视频| 欧美又色又爽又黄视频| 国产成+人综合+亚洲专区| 欧美乱码精品一区二区三区| 成人高潮视频无遮挡免费网站| 久久精品亚洲精品国产色婷小说| 又黄又爽又免费观看的视频| 不卡一级毛片| 亚洲一区二区三区不卡视频| 最近最新中文字幕大全电影3| 日日夜夜操网爽| 免费观看精品视频网站| 欧美日韩国产亚洲二区| 黄色丝袜av网址大全| 久久国产精品人妻蜜桃| 无限看片的www在线观看| 精品不卡国产一区二区三区| 麻豆成人av在线观看| 变态另类成人亚洲欧美熟女| 嫩草影视91久久| 午夜福利18| 亚洲国产高清在线一区二区三| 99久久久亚洲精品蜜臀av| 老熟妇仑乱视频hdxx| 久久亚洲精品不卡| 精品免费久久久久久久清纯| 国产欧美日韩一区二区精品| 精品熟女少妇八av免费久了| 日韩有码中文字幕| 久久久久国产一级毛片高清牌| 午夜成年电影在线免费观看| 99热精品在线国产| 欧美乱色亚洲激情| 9191精品国产免费久久| 日本一本二区三区精品| 亚洲av片天天在线观看| 亚洲专区字幕在线| 又粗又爽又猛毛片免费看| 日本 av在线| 亚洲无线在线观看| a级毛片在线看网站| 在线观看美女被高潮喷水网站 | 亚洲va日本ⅴa欧美va伊人久久| 网址你懂的国产日韩在线| 我的老师免费观看完整版| 久久香蕉精品热| 日韩免费av在线播放| 久久99热这里只有精品18| 嫩草影院精品99| 久99久视频精品免费| 国产aⅴ精品一区二区三区波| 国产精品99久久久久久久久| 又紧又爽又黄一区二区| 人人妻,人人澡人人爽秒播| 丰满的人妻完整版| 观看美女的网站| 欧美日韩一级在线毛片| 精品久久久久久成人av| 色综合婷婷激情| 欧美日本视频| 日本熟妇午夜| 中文亚洲av片在线观看爽| 久久久久亚洲av毛片大全| 日韩三级视频一区二区三区| 国产亚洲av嫩草精品影院| 欧美3d第一页| 在线播放国产精品三级| 国产高清三级在线| 亚洲一区二区三区不卡视频| 日本黄大片高清| 宅男免费午夜| 最近最新中文字幕大全免费视频| 欧美zozozo另类| 亚洲国产色片| 午夜成年电影在线免费观看| 少妇的逼水好多| 国产乱人伦免费视频| 亚洲国产精品999在线| 国产成年人精品一区二区| 制服丝袜大香蕉在线| 少妇丰满av| 亚洲性夜色夜夜综合| 久99久视频精品免费| 淫妇啪啪啪对白视频| 午夜福利在线观看免费完整高清在 | 天堂网av新在线| 又黄又粗又硬又大视频| 亚洲av成人不卡在线观看播放网| 一a级毛片在线观看| a级毛片a级免费在线| 国产精华一区二区三区| 别揉我奶头~嗯~啊~动态视频| 久久九九热精品免费| 又爽又黄无遮挡网站| 91麻豆av在线| 日本一本二区三区精品| 欧美大码av| 一个人看的www免费观看视频| 每晚都被弄得嗷嗷叫到高潮| 国产精品一区二区三区四区久久| 国产亚洲av嫩草精品影院| 久久伊人香网站| 精品不卡国产一区二区三区| 最新中文字幕久久久久 | 国内精品久久久久久久电影| 少妇的逼水好多| 人人妻,人人澡人人爽秒播| 欧美性猛交黑人性爽| 国产淫片久久久久久久久 | 亚洲国产精品sss在线观看| 欧美性猛交黑人性爽| 成年人黄色毛片网站| 国产久久久一区二区三区| 国产免费男女视频| 欧美日韩精品网址| 精品国产乱子伦一区二区三区| 一级毛片精品| 亚洲人成网站在线播放欧美日韩| 一级a爱片免费观看的视频| 午夜成年电影在线免费观看| 免费在线观看日本一区| 国产亚洲精品久久久久久毛片| 日韩 欧美 亚洲 中文字幕| 久久精品国产亚洲av香蕉五月| 悠悠久久av| 88av欧美| 亚洲国产欧美一区二区综合| 亚洲avbb在线观看| 国产精品99久久久久久久久| 国产乱人视频| 久久精品综合一区二区三区| 天堂√8在线中文| 亚洲欧美日韩高清专用| 高清在线国产一区| 成年版毛片免费区| 热99在线观看视频| 欧美激情在线99| 老司机午夜十八禁免费视频| 中文字幕av在线有码专区| 神马国产精品三级电影在线观看| 国产一区二区三区在线臀色熟女| 国产日本99.免费观看| 怎么达到女性高潮| 精品久久久久久久久久免费视频| 亚洲成人免费电影在线观看| 日本与韩国留学比较| 老汉色av国产亚洲站长工具| 别揉我奶头~嗯~啊~动态视频| 亚洲午夜理论影院| ponron亚洲| 久久精品夜夜夜夜夜久久蜜豆| 国产高清视频在线观看网站| 国产成人福利小说| 黄色片一级片一级黄色片| 在线观看舔阴道视频| 又粗又爽又猛毛片免费看| 成在线人永久免费视频| 美女高潮的动态| 在线十欧美十亚洲十日本专区| 91av网一区二区| 亚洲五月天丁香| 级片在线观看| 欧美日韩综合久久久久久 | 激情在线观看视频在线高清| 久久婷婷人人爽人人干人人爱| 岛国在线免费视频观看| aaaaa片日本免费| 成人高潮视频无遮挡免费网站| 亚洲片人在线观看| 欧美在线一区亚洲| 午夜精品久久久久久毛片777| 亚洲中文日韩欧美视频| av中文乱码字幕在线| 香蕉丝袜av| 特大巨黑吊av在线直播| 国产免费男女视频| 丁香欧美五月| 免费看十八禁软件| 精品久久久久久久久久久久久| 国产精品乱码一区二三区的特点| 男人舔女人下体高潮全视频| 美女cb高潮喷水在线观看 | 身体一侧抽搐| 国产亚洲欧美在线一区二区| 中文字幕精品亚洲无线码一区| 熟妇人妻久久中文字幕3abv| 国产免费av片在线观看野外av| 成人无遮挡网站| 日韩大尺度精品在线看网址| 成人国产一区最新在线观看| 亚洲18禁久久av| 夜夜夜夜夜久久久久| 少妇的逼水好多| 97碰自拍视频| 少妇裸体淫交视频免费看高清| 美女扒开内裤让男人捅视频| 国产亚洲精品久久久久久毛片| 国产精品日韩av在线免费观看| 日本撒尿小便嘘嘘汇集6| 色老头精品视频在线观看| 精品不卡国产一区二区三区| 亚洲av美国av| 色播亚洲综合网| 在线播放国产精品三级| 亚洲成人久久性| 视频区欧美日本亚洲| 两性夫妻黄色片| 国产成人啪精品午夜网站| 在线a可以看的网站| 五月玫瑰六月丁香| 狂野欧美白嫩少妇大欣赏| 国产伦在线观看视频一区| 97人妻精品一区二区三区麻豆| 91av网站免费观看| 99久久精品国产亚洲精品| 一二三四在线观看免费中文在| 美女免费视频网站| a级毛片a级免费在线| 亚洲欧美激情综合另类| 亚洲国产精品合色在线| 亚洲美女视频黄频| 亚洲五月婷婷丁香| 免费一级毛片在线播放高清视频| 国产av在哪里看| 少妇裸体淫交视频免费看高清| 两人在一起打扑克的视频| 亚洲va日本ⅴa欧美va伊人久久| 男人舔女人下体高潮全视频| 欧美xxxx黑人xx丫x性爽| 国产精品一区二区免费欧美| 又粗又爽又猛毛片免费看| 视频区欧美日本亚洲| 亚洲av电影不卡..在线观看| 国产一级毛片七仙女欲春2| 久久香蕉国产精品| 亚洲第一欧美日韩一区二区三区| 亚洲va日本ⅴa欧美va伊人久久| av天堂在线播放| 啪啪无遮挡十八禁网站| svipshipincom国产片| 亚洲成人久久性| 日韩欧美免费精品| 99热这里只有是精品50| 亚洲av日韩精品久久久久久密| 99久久无色码亚洲精品果冻| 精品久久久久久久久久免费视频| 男人舔奶头视频| 免费看美女性在线毛片视频| 欧美中文日本在线观看视频| 1000部很黄的大片| 亚洲国产精品999在线| 一夜夜www| 黑人欧美特级aaaaaa片| 国产三级在线视频| 国产精华一区二区三区| 日日摸夜夜添夜夜添小说| 无遮挡黄片免费观看| 国产精品久久视频播放| 在线国产一区二区在线| 午夜a级毛片| 一级作爱视频免费观看| 亚洲国产日韩欧美精品在线观看 | 2021天堂中文幕一二区在线观| 亚洲国产欧美一区二区综合| 午夜精品一区二区三区免费看| 免费看a级黄色片| 18美女黄网站色大片免费观看| 看片在线看免费视频| 久久人人精品亚洲av| 一个人免费在线观看电影 | 国产精品九九99| 久久久久国产一级毛片高清牌| 一区二区三区高清视频在线| 观看美女的网站| 亚洲第一电影网av| 日韩中文字幕欧美一区二区| 性色av乱码一区二区三区2| 免费看日本二区| 日本黄大片高清| 91在线精品国自产拍蜜月 | 搡老熟女国产l中国老女人| 2021天堂中文幕一二区在线观| 精品久久久久久久末码| 99精品在免费线老司机午夜| 2021天堂中文幕一二区在线观| 午夜精品在线福利| 欧美乱码精品一区二区三区| 18禁国产床啪视频网站| 青草久久国产| 国产亚洲精品一区二区www| 波多野结衣高清作品| 精品午夜福利视频在线观看一区| 亚洲午夜精品一区,二区,三区| 九色成人免费人妻av| 久久草成人影院| 每晚都被弄得嗷嗷叫到高潮| 午夜亚洲福利在线播放| 99精品在免费线老司机午夜| 亚洲国产精品sss在线观看| 亚洲欧美日韩高清专用| 国产精品国产高清国产av| 国产精品久久久av美女十八| 美女cb高潮喷水在线观看 | 美女大奶头视频| 国产精华一区二区三区| 欧美绝顶高潮抽搐喷水| 五月玫瑰六月丁香| 久久草成人影院| 国产午夜福利久久久久久| 露出奶头的视频| 色尼玛亚洲综合影院| 日韩人妻高清精品专区| or卡值多少钱| 精品久久久久久久久久久久久| av中文乱码字幕在线| 男人的好看免费观看在线视频| 免费在线观看视频国产中文字幕亚洲| 免费观看人在逋| 国产亚洲精品一区二区www| 国产精品精品国产色婷婷| 欧美高清成人免费视频www| 国产精品九九99| 国产精品野战在线观看| 久久久国产精品麻豆| 国产av麻豆久久久久久久| 九色成人免费人妻av| 看免费av毛片| 女生性感内裤真人,穿戴方法视频| 亚洲 欧美一区二区三区| 波多野结衣高清作品| 国内精品久久久久精免费| 深夜精品福利| 国产激情欧美一区二区| 午夜福利免费观看在线| 久久久久免费精品人妻一区二区| 黄色视频,在线免费观看| 欧美乱码精品一区二区三区| 亚洲av第一区精品v没综合| 国产精品乱码一区二三区的特点| 免费搜索国产男女视频| 黄色日韩在线| 俺也久久电影网| 久久国产精品影院| 亚洲五月婷婷丁香| 午夜视频精品福利| 美女 人体艺术 gogo| 欧美+亚洲+日韩+国产| 国产美女午夜福利| 日本与韩国留学比较| 国产成人欧美在线观看| 久久亚洲精品不卡| 一本精品99久久精品77| 久久精品影院6| 国产激情偷乱视频一区二区| 黄色视频,在线免费观看| 国产伦在线观看视频一区| 午夜亚洲福利在线播放| 国产黄片美女视频| 男插女下体视频免费在线播放| 999久久久精品免费观看国产| 亚洲成av人片免费观看| 色哟哟哟哟哟哟| 国产欧美日韩一区二区精品| 亚洲av成人不卡在线观看播放网| 首页视频小说图片口味搜索| 男人舔女人下体高潮全视频| 欧美大码av| 国产高清视频在线观看网站| 啦啦啦韩国在线观看视频| 亚洲中文av在线| 亚洲成av人片在线播放无| 叶爱在线成人免费视频播放| 婷婷亚洲欧美| 久久久久国内视频| 色哟哟哟哟哟哟| 熟女人妻精品中文字幕| av天堂在线播放| 久久久国产成人精品二区| 国产真人三级小视频在线观看| 亚洲男人的天堂狠狠| 他把我摸到了高潮在线观看| 人妻丰满熟妇av一区二区三区| 麻豆国产97在线/欧美| 小蜜桃在线观看免费完整版高清| 久久中文字幕一级| 成年版毛片免费区| 偷拍熟女少妇极品色| 亚洲 欧美一区二区三区| 久久天堂一区二区三区四区| 成年女人毛片免费观看观看9| 熟女电影av网| 亚洲av熟女| 国产熟女xx| 88av欧美| 国产高清videossex| 在线观看一区二区三区| 最新美女视频免费是黄的| 免费高清视频大片| 色综合婷婷激情| 搡老妇女老女人老熟妇| 一级黄色大片毛片| 国产欧美日韩一区二区精品| 婷婷精品国产亚洲av在线| 中出人妻视频一区二区| 国产私拍福利视频在线观看| 国产激情欧美一区二区| 日本免费a在线| 手机成人av网站| 亚洲五月婷婷丁香| 日韩精品青青久久久久久| 国产成人精品久久二区二区91| 特级一级黄色大片| 中国美女看黄片| 免费在线观看影片大全网站| 两人在一起打扑克的视频| 国产精品久久久av美女十八| 级片在线观看| 五月玫瑰六月丁香| 国产亚洲精品av在线| 69av精品久久久久久| 国产亚洲精品久久久久久毛片| 午夜精品久久久久久毛片777| 人人妻,人人澡人人爽秒播| 免费看日本二区| 欧美午夜高清在线| 看片在线看免费视频| 搡老妇女老女人老熟妇| 99视频精品全部免费 在线 | 午夜福利在线在线| 国产激情久久老熟女| 色吧在线观看| 日韩欧美在线乱码| 免费搜索国产男女视频| 两个人的视频大全免费| 首页视频小说图片口味搜索| 久久精品国产清高在天天线| 精品久久久久久久人妻蜜臀av| 香蕉丝袜av| 麻豆成人av在线观看| 成人性生交大片免费视频hd| 18禁黄网站禁片免费观看直播| av黄色大香蕉| a级毛片a级免费在线| 在线十欧美十亚洲十日本专区| 性色avwww在线观看| 两个人的视频大全免费| 精品久久蜜臀av无| 黄片小视频在线播放| 中文字幕高清在线视频| 国产成人精品无人区| 精品国产亚洲在线| 夜夜夜夜夜久久久久| 国产精品av视频在线免费观看| 免费在线观看日本一区| 成在线人永久免费视频| 麻豆成人av在线观看| 狂野欧美白嫩少妇大欣赏| 啦啦啦免费观看视频1| 黑人欧美特级aaaaaa片| 俄罗斯特黄特色一大片| 国产视频一区二区在线看| 熟女人妻精品中文字幕| 国产又色又爽无遮挡免费看| 精品一区二区三区av网在线观看| 成在线人永久免费视频| 三级男女做爰猛烈吃奶摸视频| 国产淫片久久久久久久久 | 日韩精品中文字幕看吧| 男人的好看免费观看在线视频| 日韩欧美国产一区二区入口| 欧洲精品卡2卡3卡4卡5卡区| 国产一区二区激情短视频| 一个人看视频在线观看www免费 | 亚洲在线观看片| 国产精品精品国产色婷婷| 亚洲精品一卡2卡三卡4卡5卡| 国产真实乱freesex| 丁香欧美五月| 中文字幕久久专区| 狠狠狠狠99中文字幕| 亚洲国产高清在线一区二区三| 国产视频内射| 1024香蕉在线观看| 91九色精品人成在线观看| 18美女黄网站色大片免费观看| 男人舔女人的私密视频| 亚洲国产精品久久男人天堂| 国产亚洲欧美在线一区二区| 一个人看的www免费观看视频| 欧美日韩一级在线毛片| 一a级毛片在线观看| 免费在线观看日本一区| 69av精品久久久久久| 国产精品综合久久久久久久免费| 成人亚洲精品av一区二区| 日韩三级视频一区二区三区| 成人国产综合亚洲| 天堂影院成人在线观看| 最近视频中文字幕2019在线8| av天堂中文字幕网| 很黄的视频免费| 黄色女人牲交| 国产亚洲精品综合一区在线观看| 久久久久国内视频| 最好的美女福利视频网| 最近最新中文字幕大全电影3| or卡值多少钱| 成人特级黄色片久久久久久久| 欧美黄色淫秽网站| 99精品欧美一区二区三区四区| 9191精品国产免费久久| 久久久久九九精品影院| 欧美av亚洲av综合av国产av| 国产精品永久免费网站| 色吧在线观看| 99久久精品一区二区三区| 欧美zozozo另类| 国产高清视频在线播放一区| 熟女人妻精品中文字幕| 亚洲自拍偷在线| www.熟女人妻精品国产| av在线天堂中文字幕| 午夜两性在线视频| 亚洲精品456在线播放app | 在线十欧美十亚洲十日本专区| 麻豆国产av国片精品| 国产真人三级小视频在线观看| 成人欧美大片| 日本 欧美在线| 女人高潮潮喷娇喘18禁视频| 国产在线精品亚洲第一网站| 久久中文字幕一级| 国产一区二区三区视频了| 免费看日本二区| 国产一区二区在线av高清观看| 国产乱人伦免费视频| 国产麻豆成人av免费视频| 亚洲激情在线av| 国产免费男女视频| 麻豆成人午夜福利视频| 久久亚洲精品不卡| 日韩欧美在线乱码| 久久九九热精品免费| 国产一区二区在线观看日韩 | 久久久久国产精品人妻aⅴ院| 国产真实乱freesex| 国产免费av片在线观看野外av| 亚洲午夜理论影院| 两性夫妻黄色片| 亚洲国产看品久久| 亚洲国产欧美网| 毛片女人毛片| 日韩 欧美 亚洲 中文字幕| 亚洲av中文字字幕乱码综合| 久久精品91无色码中文字幕| 日本与韩国留学比较| 看免费av毛片| 最近最新免费中文字幕在线| 欧美日本亚洲视频在线播放| 免费观看精品视频网站| 亚洲精华国产精华精| 午夜影院日韩av| 免费在线观看日本一区| 嫩草影院入口| 日韩欧美精品v在线| 窝窝影院91人妻| 亚洲精品久久国产高清桃花| 天天躁狠狠躁夜夜躁狠狠躁| 亚洲欧美日韩高清在线视频| 精品久久久久久久末码| 亚洲国产精品999在线| 天堂av国产一区二区熟女人妻| 免费看十八禁软件| 成人三级黄色视频| 99国产精品99久久久久| 美女cb高潮喷水在线观看 | 国产探花在线观看一区二区|