Biomedical subjects

San-Qiang Shi

Publications and source records attributed to San-Qiang Shi.

3 recordsLinked to original sources

PubMed2006

Regional variations in microstructural properties of vertebral trabeculae with structural groups.

STUDY DESIGN: Micro-computed tomography (CT) scanning to investigate three-dimensional microstructural properties of L4 vertebral bodies. OBJECTIVE: To identify the regional variations in the three-dimensional microstructural properties of vertebral cancellous bones with respect to structural types for the prediction of related regional fracture risks. SUMMARY OF BACKGROUND DATA: The literature contains no reports on regional variations in morphologic properties of vertebral trabeculae with microstructural types, which may shed light on the patterns of osteoporotic fractures. METHODS: Ninety cubic cancellous specimens were obtained from 6 normal L4 vertebral bodies of 6 male donors 62 to 70 years of age and were scanned using a high-resolution micro-CT system. These specimens were further divided into two groups according to the average structure model index (SMI) of the 15 trabecular specimens in each vertebral body. Adjustment for age differences was done for the microstructural parameters, i.e.-, bone volume fraction, trabecular number, trabecular thickness, structure model index, degree of architectural anisotropy, and connectivity density, to allow investigation on the regional variations in different transverse layers and vertical columns independent of age. RESULTS: Trabecular specimens with lower mass were liable to form high-SMI group and the differences in all parameters reached significance level either between columns or between layers from two groups. CONCLUSIONS: The anterior column in the high-SMI group is more susceptible to vertebral body wedge fracture; and in the low-SMI group, off-axis bone damage is most harmful to the central column of vertebral trabeculae. The data obtained may help to identify the most critical locations of fracture risks at an early stage and provide a microstructural basis for the repair and clinical treatment of vertebral fractures.

Aged↗

PubMed2005

Effect of surface roughness on dip-pen nanolithography.

In the present work, five gold thin films with various surface roughnesses were prepared by sputtering and the influence of the surface roughness of gold substrate on dip-pen nanolithography (DPN) was studied using 1-octadecanethiol (ODT) and poly(vinylidene fluoride-trifluorethylene) [P(VDFTrFE)] as inks. It was shown that surface roughness influences both the contrast in lateral force microscopy (LFM) images and the transport rate of ink. Surfaces with less roughness give good contrast in LFM images, while rough surfaces give poor contrast. The transport rate of ink increases as the roughness decreases; however, the extent of the influence is strongly ink-dependent.

Gold↗

PubMed2004

Nanofabrication with atomic force microscopy.

Atomic force microscopy (AFM) was developed in 1986. It is an important and versatile surface technique, and is used in many research fields. In this review, we have summarized the methods and applications of AFM, with emphasis on nanofabrication. AFM is capable of visualizing surface properties at high spatial resolution and determining biomolecular interaction as well as fabricating nanostructures. Recently, AFM-based nanotechnologies such as nanomanipulation, force lithography, nanografting, nanooxidation and dip-pen nanolithography were developed rapidly. AFM tip (typical radius ranged from several nanometers to tens of nanometers) is used to modify the sample surface, either physically or chemically, at nanometer scale. Nanopatterns composed of semiconductors, metal, biomolecules, polymers, etc., were constructed with various AFM-based nanotechnologies, thus making AFM a promising technique for nanofabrication. AFM-based nanotechnologies have potential applications in nanoelectronics, bioanalysis, biosensors, actuators and high-density data storage devices.

Image Interpretation, Computer-Assisted↗