[Comparative study of clinical effects of VCu IUD and TCu380A IUD were used on women who once been done cesarean section].

OBJECTIVE: To study and compare the clinical efficacies and characteristics of VCu intrauterine device (IUD) and TCu380A IUD in childbearing-aged women with previous cesarean section so as to provide rationales for an informed choice of contraceptive methods. METHODS: According to their physical status, a total of 400 women undergoing previous cesarean section were randomly provided VCu IUD and TCu380A IUD from February 2008 to August 2009. These healthy women were had no contraindication to IUD. The volunteers required voluntarily the placement of IUD. Then all of them were followed up for 3, 6 and 12 months. RESULTS: At Month 12, the pregnant rate with IUD in situ of VCu and TCu380A IUD were 1.02% and 4.64%, expulsion rate 0 and 3.1% and withdrawing rate 1.02% and 4.13% respectively. The pregnant rate was significantly different (P < 0.05); VCu showed a lower expulsion and withdrawing rate than that in TCu380A (P < 0.05); the continuation rate of VCu was higher than that of TCu380A (P < 0.05). CONCLUSION: VCu offers a better efficacy of contraception with a lower expulsion and withdrawing rate, a higher continuation rate and a simpler placement method.

[The study on Raman spectra of Si nanowires].

Phonon confinement effect results in an redshift and asymmetric broadening in the low-frequency side of Raman spectra of intrinsic silicon nanowires (SiNWs), but is not the only factor impacting the Raman spectrum of SiNWs. At high incidence laser power densities, laser heating gives a redshift and symmetric broadening, and Fano interference between the scattering from the k = 0 optic phonon and the electronic continuum scattering from laser-induced carriers gives an asymmetric line shape, i. e. Fano line shape. Furthermore, due to phonon confinement effect, the fundamental k = 0 Raman selection rule is relaxed, allowing phonons away from the Brillouin zone center to participate Raman scattering too, therefore, some new weak Raman signals appear at about 604 and 423 cm(-1) in addition to the usual silicon peaks at 520, 302 and 964 cm(-1) for silicon nanowires with small diameter.

[X-ray absorption spectroscopy study on nanowires and nanotubes of carbon and silicon].

Due to the different sampling depth, the total electron yield (TEY) is sensitive to the surface and near surface region, while the fluorescence yield (FLY) probes the information of the bulk. Thus the combined use of TEY and FLY provides a powerful evidence for identifying the whole sample whether or not it is a nanoscale material, and is a supplement of the conventional methods for characterizing nanoscale materials, such as TEM and XRD. With analyses of X-ray absorption spectra recorded in TEY and FLY mode, it could be used for studying the mechanism of growth, orientation, chemical bonding, defect and helicity of nanowires and nanotubes exactly and reliably. Therefore, it is believed that X-ray absorption spectroscopy is a powerful characterization tool for the study of nanoscale materials, which has some super advantages over conventional methods.