Biomedical subjects

Qing-lin Guo

Publications and source records attributed to Qing-lin Guo.

7 recordsLinked to original sources

PubMed2005

[Effects of gas composition and pressure on the intensity and quality of the plasma induced by a high-energy neodymium glass laser].

In this experiment, the effects of gas composition and pressure on the intensity and quality of the plasma induced by a high-energy neodymium glass laser were studied. The experimental results show that the spectral intensity of the plasma in the argon atmosphere is stronger than that in the air when the pressure is the same. For the steel alloy sample, the intensities of the emission spectrum reach the maximum values when the argon pressure is 0.8 x 10(5) Pa. The self-absorption phenomena of Al II 308.22 and Al II 309.27 nm lines strengthen with the increase of the pressure, and even serious self-reversal appears when the pressure is (0.8-0.9) x 10(5) Pa. The temperature of plasma also raises with the increase of the pressure. When the argon pressure is 0.93 x 10(5) Pa, t h e temperature is about 1500 K higher than that when the argon pressure is about 0.43 x 10(5) Pa.

Aluminum↗

PubMed2005

[Study on analytic precision of laser microemission spectral analysis in argon atmosphere at reduced pressure].

According to mathematic statistics, data for laser microemission spectroscopic analysis were selected, which were collected with the use of CCD (charge-coupled device) in arg on atmosphere at reduced pressure. By selection, the effects of some factors, such as the difference of bore ablated on the sample surface by the laser, the distribution nonuniformity of element in the sample, and the fluctuation of output energy of the laser, etc. were reduced. The method that improves analytic precision of laser microemission spectroscopic analysis was studied. And quantitative analysis of Cu, Zn and Mg in aluminum alloy standard samples was performed, using the Cu (I) line at 324.7 nm, the Zn (I) line at 334.5 nm, and the Mg (I) line at 383.8 nm. The results show that the RSDs of relative intensity of the spectral lines of Cu, Zn, Mg are 1.80%, 4.35% and 6.29% respectively, and the RSDs of quantitative analysis of them are 10.1%, 6.98% and 8.17% respectively. The relative errors of the average of analysis of them are -3.76%, 3.62% and -1.62% respectively.

Algorithms↗

PubMed2005

[Determination of Eu in long-afterglow of the SrAl2O4:Eu2+, Dy3+ phospher samples by LMESA].

A method for the determination of Eu in Long-aferglow of the SrAl2O4:Eu2+, Dy3+ phospher samples by laser microemission spectral analysis was developed. And the accuracy of this method was studied. Analyses of Eu in Long-aferglow of the SrA1204: Eu2+, Dy3+ phospher samples, using the Eu (11) line at 412.973 nm, show that RSD of relative intensity of spectral lines is 4.3%, RSD of quantitative analysis is 7.4%, the average of quantitative analysis is 2.13%. Compared with the content before samples synthesized, it can be concluded that the content of Eu in the SrAl2O4:Eu2+, Dy3+ phospher samples synthesized by high temperature solid phase reaction has an obvious increase.

Aluminum Oxide↗

PubMed2005

[Effect of lens-to-sample distance on laser-plasma radiative properties].

In the present paper, the effect of lens-to-sample distance (LTSD) on the radiative properties from the plasma induced by a high-energy neodymium glass laser (approximately 25J) in the argon ambient gas at a pressure of 0.43 x 10(5) Pa was studied. The experimental results showed that when the focus point of the focusing lens (f = 130 mm) shifts above and below the sample surface, the radiation intensities of the plasma, the excitation temperature, and the mass of ablated material are all changed, and their maxia appear at a focusing location of the laser beam, which is about 0.4 mm under the sample surface for alloyed-steel samples. If soil samples are used as the targets, the emission intensities of the laser plasma and the mass of ablated material have the maxima at a focus position about 0.2 mm below the sample surface. To investigate the influence of LTSD on the shape of the laser plasma, the images of the plasma formed have been shot in argon and air for the alloyed-steel samples. From these results, it was found that the properties of the laser plasma depend strongly on the LTSD.

English Abstract↗

PubMed2004

[Experimental study on laser-induced plasma and its application to spectral analysis].

The article summarizes the progress in the experimental study on laser-induced plasma and its application to spectral analysis domestically and abroad in recent years. It emphatically elaborates the experimental research on the formation, radiation, electron temperature, electron density, and expansion velocity of laser-induced plasma under different conditions (gas composition and pressure, laser energy, laser wavelength, power density and observation height). In addition, in the respect of material composition analysis using the laser-induced plasma, the article mainly interprets two aspects: one is the way to collect directly the plasma emission so as to analyze solid, liquid and gaseous samples, the other is the spectrochemical analysis when laser ablation and ICP are used together. And the article also discusses the factors that influence the precision and the limit of detection.

Clinical Laboratory Techniques↗

PubMed2003

[Study on the quality of spectral line of laser microprobe emission spectral analysis].

In this paper, the quality improvement of Laser Microprobe Emission Spectral Analysis (LMESA) lines in argon atmosphere at reduced pressure was experimentally investigated. The experimental setup consists of a YGJ-II laser micro-spectral analyzer and a photo-electro detection system. The temporal behavior and the intensity distribution of Cu I 324.7 nm and Cu I 327.4 nm lines of the copper alloy standard samples were studied. The results show that LMESA spectrum strongly depends on the environment gas, its pressure and the auxiliary excitation parameters. When the diameter at the end of graphite auxiliary electrodes is 1.5 mm, the distance between the electrodes is 4 mm, the center of the electrodes is 3 mm above the sample surface, the voltage of the auxiliary excitation is 1,300 V and the argon pressure is 33.2 Kpa, the emission time of Cu I 324.7 nm and Cu I 327.4 nm is about 500 microseconds longer than that in the air. The emission intensity of Cu I 324.7 nm and Cu I 327.4 nm is about 4 times higher than that in the air at the same pressure and is about 2 times higher than that in the air at normal pressure. The full width at half maximum of the spectral lines is obviously narrowed.

Argon↗

PubMed2003

[Study on the emission spectra of aluminum plasma induced by high energy laser].

The intensities of emission spectra of laser-induced alloy aluminum plasma, with the use of a neodymium glass laser (laser pulse energy is about 25 J), were experimentally studied in argon atmosphere. The effects of atmosphere pressure, height from the observed location of the plasma to the sample surface, operating voltage, and power density of the laser on the signal intensities of emission spectra were discussed. Experimental results showed that the intensities of emission spectra are strongest under 88 kPa of gas pressure. With the increase of the height from the observed location of the plasma to the sample surface, the intensities of emission spectra decrease clearly. At the pressure of 88 kPa and the height of 1.5-2 mm, the emission spectra have maximum intensities. In addition, the spectral line intensities are enhanced significantly with the increase of operating voltage and power density.

Alloys↗