Biomedical subjects

Xiao-xuan Xu

Publications and source records attributed to Xiao-xuan Xu.

8 recordsLinked to original sources

PubMed2006

[The measurement of the ratio of primary hydroxyl group to second hydroxyl group in polyether polyol by near infrared spectrum].

The method of near infrared spectrum, combined with derivative spectrum and multiple linear regression was applied to measure the ratio of primary hydroxyl group to second hydroxyl group in polyether polyol. The authors obtained good predictive results by using the method in this experiment. The work is very helpful for the on-line measurement of polyether polyol.

English Abstract↗

PubMed2006

[The three-dimension spectral subtraction fluorescence to check adulteration of diesel oil by 120# solvent naphtha].

The characteristics of a adulterated sample of diesel oil by 120# solvent naphtha were studied with three-dimension spectral subtraction fluorescence technique, and it is shown that the technique could determine quickly whether there is a adulterated sample of 120# solvent naphtha in diesel. At the same time, by measuring the volume of three-dimension spectral subtraction fluorescence graph, the authors found that this total volume is directly related to the concentration of the adulterant present in the sample. The study is important for us to analyse whether there is a adulterated sample of 120# solvent naphtha in diesel, and is of significance for us to maintain the stability of market.

English Abstract↗

PubMed2006

[Study of poly (3,4-ethylene dioxythiophene) : poly (styrene sulfonate) by in-situ resonance Raman spectroscopy].

Poly (3,4-ethylene dioxythiophene) (PEDOT): Poly (styrene sulfonate) (PSS) has attracted a lot of interest for application in organic electronics due to good stability and high electronic conductivity in its doped state. Indeed, thin layers of PEDOT:PSS was regularly used in light emitting diodes (PLEDs) as hole injection and transportation layer. Here, Doping and dedoping states of PEDOT:PSS were studied by absorbance spectra and Raman spectra. A new absorption band centered at 620 nm was observed on dedoped PEDOT:PSS. Consistently, Raman signals of dedoped PEDOT:PSS are resonantly intensified since the Raman excitation wavelength (633 nm) is set in the enhanced absorption band. So it gives a sensitive way to study the doping and dedoping states of PEDOT:PSS. Furthermore, for the encapsulated polymer light-emitting diodes, Raman spectroscopy is a powerful way to study the polymer layers inside the devices.

English Abstract↗

PubMed2004

[Studies on human breast cancer tissues with Raman microspectroscopy].

The microscopic Raman spectra from normal and malignant human breast tissues have been measured and investigated. The spectral differences and changes between normal and malignant breast tissue samples mainly involve: (1) the band from the symmetric stretching modes of PO2- group in the DNA shifts from 1082 to 1097 cm(-1) and becomes stronger. The intensity of the symmetric stretching modes of O-P-O at 817 cm(-1) in RNA increases greatly. (2) The bands of Amide I and III at 1657 and 1273 cm(-1) change to 1662 and 1264 cm(-1) respectively with their intensity and band width increasing. The peak of the C-O stretching modes in the amino acids shifts to higher wave number. The tryptophan band at 1368 cm(-1) almost disappears. (3) Fewer characteristic Raman bands from lipids are observed. These spectral changes indicate that nucleic acids increase in contents relatively, while their conformation changes in cancer tissues. The proteins show various conformations and disorder structures with their molecular hydrogen bonds nearly broken. The contents of lipids decrease obviously. This investigation shows that Raman microspectroscopy is useful to biochemical study and vivo diagnosis of human breast cancers.

Amides↗

PubMed2004

[Study on the degradation of polymer light-emitting diodes by in-situ micro-Raman spectroscopy].

The authors report Raman degradation study of polymer light-emitting devices under ambient conditions. In order to investigate the chemical degradation reaction in polymer light-emitting diode (PLEDs) devices, the chemical structure of the poly (2-(4-Ethylhexyl) phenyl-1, 4-phenylene vinylene) (P-PPV) polymer was analyzed by micro-Raman spectroscopy during the lifetime of the devices. The evidence for the reduction of conjugation length is provided by Raman spectroscopy. This reduction of theconjugation length, which dramatically increases the resistance and cuts off the current density, was the main reason for the failure of lighting. These findings provide an important insight into the intrinsic degradation mechanisms of the polymer LEDs and help in the development of even more stable devices.

Electrochemistry↗

PubMed2004

[Adopting the method of principal components analysis combined with correlation coefficient to increase the predicted concentration's accuracy of benzene and its homology mixture].

The concentrations of benzene and its homology mixture were measured by near infrared spectra, and the emphasis was put on the character of the principal component and its physical significance. It is pointed out that the anterior principal components are very similar to the correlation coefficient of the multi-component solution and the theoretical proof for the right condition is given. The high frequency noise of the system can be checked out by principal component combined with the correlation coefficient. Removing the noise can greatly increase the accuracy of the prediction model.

Benzene↗

PubMed2002

[Raman scattering of single-wall carbon nanotubes produced using Y/Ni catalyst].

Single wall carbon nanotubes (SWNTs) were synthesized by electric are discharge method with a mixture of nickel and yttrium as catalysts. The examination results of scanning electronic microscope and transmission electronic microscope indicate that the yield of SWNTs in the sample were high. SWNTs have been investigated by Raman scattering techniques with excitation wavelengths in the range of 514.5 to 782.0 nm. We have observed some differences in the frequencies and intensities of the radial breathing modes. The electronic density of states of SWNTs was calculated using the Brillouin zone folding. A graphical method was proposed for assigning Raman peaks of the radial breathing modes (RMB) based on the data of diameters, RBM frequencies and electronic density of states of SWNTs. The radial breathing modes on SWNTs are assigned. The results indicate that the diameter distribution of SWNTs is in the range of 0.79-1.76 nm, and the SWNTs with diameter 1.45 nm are in the majority. The metallic and semiconductor tubes are all present in the sample.

Catalysis↗

PubMed2002

[Research of image spectrometer using linear variable interference filter].

In the present work we have designed a small-size portable imaging spectrometer using linear variable interference filter, with CCD camera as picture sensor, and micromotion stage to bring along interference filter which scan across every pixel of CCD array. The difference column pixel in the picture which we get at every step is monocolour partial image under different wavelength, with the step by step, these column monocolour pixels change the wavelength. And finally we reassembled these images and get the whole monocolour image with different wavelength. The interval of sweep step length decided by the required spectrum resolution and the required wavelength interval of different pictures. The experiment demonstrated the resolution of this spectrometer is about 16 nm, but that major reason of the limiting resolution is the band width of the linear variable interference filter. The spatial resolution of the instrument ultimately decided by CCD, filter and imaging lens. This spectrometer has some characters such as compact structure, higher spatial resolution, higher spectrum resolution, higher scan rate and so on. Furthermore, an application of this instrument in distinguishing from camouflage have been showed.

Analog-Digital Conversion↗