Biomedical subjects

Jianxin Gao

Publications and source records attributed to Jianxin Gao.

6 recordsLinked to original sources

PubMed2006

3D finite element mesh generation of complicated tooth model based on CT slices.

An interactive three-dimensional finite element generation method is presented for modelling a multi-connected teeth and mandible structure. The tetrahedron is chosen as the basic element type due to its rigorous adaptability to structures with geometric complexities. The mesh generation is implemented by allocating two quadrangles in adjacent CT image slices to form a set of tetrahedrons. By examining all the possible allocations and their degradations, an algorithm is developed for interactive mesh generation, resulting in a series of tetrahedrons consistent with all the others without overlapping and spacing. The developed system was applied to a tooth-mandibular structure, generating a complicated 3D FEM model consisting of 4762 nodes and 18,534 tetrahedral elements with nine different materials. This 3D model was successfully used to evaluate different tooth restoration strategies, which proved the viability and effectiveness of the proposed method.

Finite Element Analysis↗

PubMed2004

Predictive cardiac motion modeling and correction with partial least squares regression.

Respiratory-induced cardiac deformation is a major problem for high-resolution cardiac imaging. This paper presents a new technique for predictive cardiac motion modeling and correction, which uses partial least squares regression to extract intrinsic relationships between three-dimensional (3-D) cardiac deformation due to respiration and multiple one-dimensional real-time measurable surface intensity traces at chest or abdomen. Despite the fact that these surface intensity traces can be strongly coupled with each other but poorly correlated with respiratory-induced cardiac deformation, we demonstrate how they can be used to accurately predict cardiac motion through the extraction of latent variables of both the input and output of the model. The proposed method allows cross-modality reconstruction of patient specific models for dense motion field prediction, which after initial modeling can be used for real-time prospective motion tracking or correction. Detailed numerical issues related to the technique are discussed and the effectiveness of the motion and deformation modeling is validated with 3-D magnetic resonance data sets acquired from ten asymptomatic subjects covering the entire respiratory range.

Algorithms↗

PubMed2003

Handling and detection of 25 amol of near-infrared dye deoxynucleotide conjugates by capillary electrophoresis with laser-induced fluorescence detection.

Near-infrared dyes are attractive as labeling reagents to enhance sensitivity in trace analysis largely because background fluorescence is low in this spectral region. Here we demonstrate, towards a goal of detecting DNA adducts in small biological samples, that some near-infrared (IR) dye-labeled deoxynucleotides can be separated and detected with high sensitivity by capillary electrophoresis (CE)-laser-induced fluorescence detection (LIF) in a realistic way (handling detection limit of 25 amol) for near-IR dye-labeled deoxynucleotides. This detection limit is achieved by polarity-switching injection of 2.0 microl from a volume of 5.0 microl, in which the compounds are 5 x 10(-12) mol/l in 50% aqueous methanol. Although the adenine and cytosine-containing conjugates co-migrated, the other three (guanine, N2-ethylguanine and thymine) were resolved.

Coloring Agents↗

PubMed2002

Xanthamide fluorescent dyes.

Two derivatives of fluorescein, termed "xanthamides," were prepared from fluorescein, an inexpensive dye. Relative to fluorescein, which contains a 6-phenolic OH and a 2'-carboxyl, the first derivative (5) contains a carboxymethyl ether at the 6-position and a secondary amide of dimethylamine at the 2'-position. The second derivative (8) contains a corresponding 6-methyl ether and a secondary amide of isonipecotic acid at the 2'-position. Thus, both derivatives contain a single carboxyl group, making them monofunctional. Especially 8 is much more photostable (about 10 times) than either fluorescein or BODIPY FL dye when exposed to ordinary light (tungsten light bulb). When tested for relative response in a capillary electrophoresis instrument fitted with an argon ion laser detector (488 nm) and a broad band emission filter, 8 was found to be 4-fold less bright than fluorescein. Both xanthamides, consistent with prior literature on 6-O-alkylated fluorescein, exhibit relatively pH-independent fluorescence (pH 4-10 was tested here). Because they possess two absorbance maximums, the xanthamides can be excited over a broader wavelength range than fluorescein or BODIPY. These collective properties of the xanthamides will make them advantageous over fluorescein and BODIPY dyes for some applications.

Boron Compounds↗

PubMed2002

Virtual tagging: numerical considerations and phantom validation.

This paper presents a virtual tagging framework for measuring, as well as visualising, myocardial deformation using magnetic resonance (MR) velocity imaging. Tagging grids are allocated artificially according to the deformation gradient with varying shapes and densities. The control points are then deformed such that the difference between the induced deformation velocity and that of actually measured MR data is minimum. A full three-dimensional implementation of the technique combined with the mass conservation constraint is provided. Numerical considerations of applying the proposed framework and different optimization strategies have been investigated with both simulated and phantom experiments. The accuracy of the technique in terms of following material deformation is compared with that of conventional tagging technique.

Finite Element Analysis↗

PubMedDate not supplied

Use of shadow-speckle correlation method for 3D tooth model reconstruction.

This study presents a method of using shadow-speckle correlation to reconstruct a 3-dimensional (3D) tooth model. Compared with other methods based on laser or optical geometric measurements, the shadow-speckle method overcomes their limitations by using a digital image correlation to reconstruct a 3D tooth model. Using plaster models 4 times the normal tooth size showed that the accuracy of the reconstructed model was estimated at roughly 30 microm, which potentially could be used in direct intraoral applications.

Humans↗