Biomedical subjects

Duan-fu Xu

Publications and source records attributed to Duan-fu Xu.

9 recordsLinked to original sources

PubMed2006

[FTIR spectroscopic studies of hydration effect on the molecular structure of polyether urethane].

The interaction between water molecules and the polar groups in linear polyether urethane was studied by FTIR and subtraction spectroscopy technique. Direct proofs of the combining of water molecule and carbonyl group were obtained. The reorganizations of the ether linkage, carbamate, and carbon-hydrogen chain after hydration were also observed. These results suggest that the FTIR and subtraction spectroscopy technique could be a useful tool to investigate the hydration mechanism of polymer materials.

English Abstract↗

PubMed2006

[Structural study on the transparency of cross-linked polyester polyurethane].

The polyurethane material with cross-linked structure was synthesized using half pre-polymerization method. IR, UV-Vis, TEM and XRD methods, and physical properties measurements indicate that different moulding temperatures influence the apparent transparence of polyurethane and abrasive performance, and the nature of these changes is related to the conditions of processand chemical reaction which lead to gradual micro-phase separation of the polyurethane molecules with different compositions, resulting in the domain-forming with the size of sub-micro-, micro- and even more than ten micro-meters. Such domains aggregate one another to form particles with different shapes and complicated structures. The increase in the amount and size of these heterogeneous particles, distributed in the medium of transparent polyurethane, is the main cause that brings on an opaque appearance of polyurethane.

English Abstract↗

PubMed2005

[The study on the growth process of ZnO nanorods].

Albstract The authors synthesized ZnO nanorods by calcining the precursor composed of PVP and Zn(CH3COO)2.2H2O at 300 degrees C. In order to investigate the growth process of ZnO nanorods, the precursor was calcined for different time (0.5, 3, 12, 24 h) and the corresponding products were measured by TEM, HR-TEM (high-resolution transmission electron microscopic), SAED (selected-area electron diffraction pattern) and XRD. The result showed that there were ZnO crystallites in the precursor of PVP and Zn(CH3COO)2.2H2O, which was dried at 110 degrees C. When the precursor was calcined at 300 degrees C for 0.5 h, ZnO nanorods could be observed with diameter of 50 nm and the nanorods consisted of two parts. One was compact nanorod with diameter of about 30 nm and the other part was ZnO crystallites attaching around the nanorod. This phenomenon indicated that there might be a transverse growth direction of ZnO nanorods at early time of crystal growth. When the precursor was calcined for 3 h, the products were direct and smooth single crystal ZnO nanorods. Further increasing the calcining time at 300 degrees C could improve the length of the ZnO nanorods in a certain extent while the diameter changed a little. The HR-TEM results showed that the growth direction of ZnO nanorods was along c axis.

Hot Temperature↗

PubMed2005

[Characterization of the orientation of polymer material by non-polarized raman laser light spectroscopy].

The non-polarized Raman laser light was used to investigate the anisotropic polymers including polypropylene fiber, nylon 6 flat fiber, and polyethylene pipe. The Raman spectra of the same samples with different location relative to the incident direction of laser beam show obvious differences. The present result extends the application of Raman spectroscopy to the characterization of oriented polymers samples.

Anisotropy↗

PubMed2005

[Novel infrared spectroscopy methods for clinical diagnosis of tumor].

In this paper, the authors have reviewed their investigation on the clinical detection of tumor tissues by infrared spectroscopy in recent ten years. Based on the comparison of different IR spectroscopic methods such as IR transmission spectroscopy, micro-IR spectroscopy etc, the authors found the good consistency of the results of ATR (attenuated total reglection) IR spectroscopic method with those of pathological biopsy. The authors have directly measured the IR spectra of frozen tissues stored in liquid nitrogen and freshly resected tissues, and have realized the measurement of tumor tissues in vito during the operation process using a specially designed IR spectrometer connected with a mid-IR fiberoptic with an ATR probe. The authors have investigated the malignant and normal tissues including parotid, esophagus, stomach, colon, liver, gallbladder, breast, thyroid etc. and compared with the pathological results. The accuracy of this novel IR detection method is more than 90%.

Humans↗

PubMed2005

[The studies on YCl3/PEU system by rheology analysis and FTIR].

FTIR spectroscopy and rheology analysis were applied to study the YCl3/PEU system. It is apparent that modification with lanthanide complexes such as yttrium leads to a slight increase in viscosity of the polyether urethane solution. The authors conclude that this may be due to the interaction between the lanthanide ions and the polar group in urethane.A new band appears at 1650 cm(-1) in the infrared spectra of the YCl3/PEU system, which corresponds to the new carbonyl structure formed through the coordination with yttrium cations. The dynamic rheological behaviors of the solutions demonstrate the interaction furthermore. A higher molecular weight formed with the higher concentration of the lanthanide ions in this DMF solution. And this could be an effective method to characterize the structure of the polymer solutions.

English Abstract↗

PubMed2004

[Investigation of PP/PE blend with FTIR mapping].

The polypropylene/polyethylene (PP/PE) blends with different weight ratio were studied by FTIR spectroscopy. The characteristic absorption bands of PP and PE in different blends were compared. It was found that the ratio of the characteristic absorption peak areas of PP to those of PE is correlated with the weight ratio of PP to PE in the blends. Based on the above results, FTIR mapping technique was applied to characterize the samples prepared by embedding PP fiber into molten PE film, and the distribution of PP and PE in the blends can be obtained from the ratio of the characteristic peak areas of PP to PE. Good agreements have been observed between the IR mapping image and the image obtained using polarized optical microscope. These results indicated that FTIR mapping technique is an effective tool to investigate the phase separation behavior of polymer blends based on the ratio of the characteristic peak areas of different polymers.

English Abstract↗

PubMed2004

[The interaction between La and polyurethane system].

A series of polyether polyurethane (PU)-LaCl3 composites with different lanthanum contents were prepared. DSC results indicate that LaCl3 promotes phase transition behavior of the LaCl3/PU composites, which causes the endothermic peak at 11.58 degrees C to disappear. FTIR spectroscopy demonstrates that significant variation can be observed. The peak at 1633 cm(-1) attributed to carbonyl vibration and the peak at 3311 cm(-1) attributed to N-H stretching band moves to 1647 cm(-1) and 3355 cm(-1), respectively, when LaCl3 is introduced into the PU system. A new band (-200 cm(-1)) assigned to the La-O band was observed, and the far IR result provided a direct evidence of the coordination between La3+ ion and C=O group of PU system.

English Abstract↗

PubMed2003

[Interaction between polyamide and zinc salt].

X-ray diffraction and FTIR spectroscopic method have been used to investigate the interaction between the amide group of nylon 6 and zinc chloride. The nylon sample obtained by adding formic acid solution of nylon into aqueous solution saturated by zinc chloride is significantly different from the nylon precipitated after mixing formic acid solution of nylon and water. X-ray diffraction results demonstrate that nylon precipitated from water has crystallization while the sample acquired from saturated solution of ZnCl2 remains amorphous. FTIR spectroscopic study shows that the interaction between zinc ion and the amide group of nylon 6 brings about significant variation of amide I and II bands and prevents the crystallization of nylon. The interaction between nylon and zinc ions may be helpful in the development of a new method of manufacturing new nylon material with superior performance.

Chlorides↗