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Biomedical subjects

Sheng Xu

Publications and source records attributed to Sheng Xu.

10 recordsLinked to original sources
PubMed2006

Synthesis of CdSe, ZnSe, and ZnxCd1-xSe nanocrystals and their silica sheathed core/shell structures.

Uniform ZnxCd1-xSe nanocrystals have been prepared at the artificially designed water-oil interface using Na2SeO3, Cd(NO3)2, and Zn(NO3)2 as precursors. The chemical composition and band gap of the ZnxCd1-xSe nanocrystals can be adjusted via different combinations of source material. The coating of a SiO2 shell could transform the hydrophobic particles into hydrophilic particles. An advantage of this method is that a water phase could be added to the oleic acid (OLEA) synthesis system, which could be extended to make the synthesis of various nanocrystals more simple and flexible.

Journal Article↗
PubMed2006

A positive-microemulsion method for preparing nearly uniform Ag2Se nanoparticles at low temperature.

A positive-microemulsion system (water/sodium linoleate/hexane) was used to make uniform Ag2Se nanoparticles at low temperature (7-10 degrees C) within five to ten minutes. The proposed interface-reaction mechanism was corroborated by transmission electron microscopy (TEM), IR spectroscopy, and X-ray photoelectron spectroscopy (XPS) results. This is a general method that is ideal for making other uniform nanoparticles on a large scale through simple precipitation reactions.

Journal Article↗
PubMed2006

Lung deformation estimation and four-dimensional CT lung reconstruction.

RATIONALE AND OBJECTIVES: Four-dimensional (4D) computed tomography (CT) can be used in radiation treatment planning to account for respiratory motion. Current 4D CT techniques have limitations in either spatial or temporal resolution. In addition, most of these techniques rely on auxiliary surrogates to relate the time of the CT scan to the patient's respiratory phase. We propose a 4D CT method for lung applications to overcome these problems. MATERIALS AND METHODS: A set of axial scans are taken at multiple table positions to obtain a series of two-dimensional images while the patient is breathing freely. Each two-dimensional image is registered to a reference CT volume. The deformation of the image with respect to the volume is used to synchronize the image with the respiratory cycle assuming that there is no phase variation along the craniocaudal direction. The reconstructed 4D dataset is a series of deformable transformations of the reference volume. RESULTS: A synthetic 4D dataset showed that the registration error is less than 5% of the image deformation. A swine study showed that the algorithm can generate better image quality than the image sorting method. A respiratory-gated 4D dataset showed that the algorithm's result is consistent with the ground truth. CONCLUSION: The algorithm can reconstruct good quality 4D images without external surrogates even if the CT scans are acquired under irregular respiratory motion. The algorithm may allow for reduced radiation dose to the patient with a limited loss of image quality. Although the phase variation exists along the craniocaudal direction, the 4D reconstruction is reasonably accurate.

Algorithms↗
PubMed2006

[Clinical study of immediate placement and early loading of dental implants].

OBJECTIVE: To evaluate the clinical results of immediate placement and early loading of dental implants. METHODS: Sixty-four dental implants were inserted into the edentulous section of 37 patients immediately after the teeth were extracted. 36 implants were inserted by one-stage operation procedure, of which 17 implants were loaded immediately in 3 edentulous jaws by temporary mandibular overdenture. Fixed crown restoration were completed on 14 implants in 1 - 2 months and on 22 implants in 3 - 4 months. The two-stage operation for another 28 implants were performed after 3 - 6 months and then were restored by routine methods. RESULTS: All implants were inserted successfully and stable. There was no peri-implantitis and X-ray films indicated that no remarkable bone resorption occurred. There were no significant differences in the peri-implant depths of gingival pocket between early loading implants and routine restoration. CONCLUSIONS: Dental immediate implant and early loading after implantation can shorten the treatment period of implant-supported prosthesis. The short-term clinical performance was not different from the routine method.

Adolescent↗
PubMed2006

[Comparative study on GOD-trinder method for measuring glucose in serum with different benzene-original phenols].

Comparative studies were carried out on GOD-trinder method for measuring glucose in serum with four different kinds of benzene-original phenols-phenyl hydroxide, 2,4-dichlorophenol, 2,6-dichlorophenol and resorcinol. It is shown that when the three coloring systems-phenyl hydroxide, 2,4-dichlorophenol or resorcinol coupling with glucose oxidase-peroxidase-4-a minoantipyrine-hydrogen peroxide (GOD-POD-4-AA-H2O2) respectively were used for clinical assay of glucose in serum, the determination results showed no significant differences (P > 0.05). Compared with phenyl hydroxide, the coloring system of 2,4-dichlorophenol is better in the aspects of sensitivity, precision and accuracy; the resorcinol system has lower sensitivity with the advantage of faster detecting velocity, and larger linear range, and can be used for on-line rapid analysis of samples with more concentrated glucose in industry.

Blood Glucose↗
PubMed2006

[Research advances in thermotolerance regulation of cool-season turfgrass].

Among abiotic stresses, high temperature is one of the important ecological factors limiting the growth and development of cool-season turfgrass in the transitional and warm climatic regions, especially during hot summer, which leads to the decline of turf quality, loss of chlorophyll, metamorphism of protein, decrease of photosynthetic activities, and even, cell death. Therefore, how to overcome the difficulty for cool-season turfgrass in spending hot summer successfully, especially in the transitional and warm climatic regions, is a serious problem. Based on the statement of regulation principle in thermotolerance, the research advances in thermotolerance regulation of cool-season turfgrass were reported, including the advances in morphological, ecological, physiological, and biochemical characters in thermotolerance, and the advances in thermotolerance regulation by proper management and regulation measurements such as lowing the soil temperature, application of growth regulators and fertilization, proper clipping, and irrigation.

Adaptation, Physiological↗
PubMed2005

Lung deformation estimation and four-dimensional CT lung reconstruction.

Four-dimensional (4D) computed tomography (CT) image acquisition is a useful technique in radiation treatment planning and interventional radiology in that it can account for respiratory motion of lungs. Current 4D lung reconstruction techniques have limitations in either spatial or temporal resolution. In addition, most of these techniques rely on auxiliary surrogates to relate the time of CT scan to the patient's respiratory phase. In this paper, we propose a novel 4D CT lung reconstruction and deformation estimation algorithm. Our algorithm is purely image based. The algorithm can reconstruct high quality 4D images even if the original images are acquired under irregular respiratory motion. The algorithm is validated using synthetic 4D lung data. Experimental results from a swine study data are also presented.

Algorithms↗
PubMed2005

Precision targeting of liver lesions using a novel electromagnetic navigation device in physiologic phantom and swine.

Radiofrequency ablation of primary and metastatic liver tumors is becoming a potential alternative to surgical resection. We propose a novel system that uses real-time electromagnetic position sensing of the needle tip to help with precision guidance into a liver tumor. The purpose of this study was to evaluate this technology in phantom and animal models. Using an electromagnetic navigation device, instrumented 18 g needles were advanced into radioopaque tumor targets in a respiratory liver phantom. The phantom featured a moving liver target that simulated cranio-caudal liver motion due to respiration. Skin-to-target path planning and real-time needle guidance were provided by a custom-designed software interface based on pre-operative 1 mm CT data slices. Needle probes were advanced using only the electromagnetic navigation device and software display. No conventional real-time imaging was used to assist in advancing the needle to the target. Two experienced operators (interventional radiologists) and two inexperienced ones (residents) used the system. The same protocol was then also used in two anesthetized 45 kg Yorkshire swine where radioopaque agar nodules were injected into the liver to serve as targets. A total of 76 tumor targeting attempts were performed in the liver phantom, and 32 attempts were done in the swine. The average time for path planning was 30 s in the phantom, and 63 s in the swine. The median time for the actual needle puncture to reach the desired target was 33 s in the phantom, and 42 s in the swine. The average registration error between the CT coordinate system and electromagnetic coordinate system was 1.4 mm (SD 0.3 mm) in the phantom, and 1.9 mm (SD 0.4 mm) in the swine. The median distance from the final needle tip position to the center of the tumor was 6.4 mm (SD 3.3 mm, n=76) in the phantom, and 8.3 mm (SD 3.7 mm, n=32) in the swine. There was no statistical difference in the planning time, procedure time, or accuracy of needle placement between experienced and inexperienced operators. The novel electromagnetic navigation system allows probe delivery into hepatic tumors of a physiologic phantom and live anesthetized swine. The system allows less experienced operators to perform equally well as experienced radiologists in terms of procedure time and accuracy of needle probe delivery.

Animals↗
PubMed2005

[The effect of exogenous glucose, fructose and NO donor sodium nitroprusside (SNP) on rice seed germination under salt stress].

The effects and the relationship between soaking rice seed of exogenous glucose, fructose and nitric oxide (NO) donor sodium nitroprusside (SNP) on the seed germination under salt stress were investigated. The results showed that employment of exogenous fructose, glucose and NO donor SNP could significantly promote the germination index and the early germination rate of rice seed under salt stress. Also, SNP pretreatment enhanced endogenous glucose and fructose contents. Effects of exogenous glucose and fructose combined with different concentrations of SNP on the rice seed germination and seedling growth under salt stress were surveyed. The results also showed that there existing positive effect of application of glucose plus SNP on the rice seed germination in comparison with existing a few negative effects of fructose plus SNP pretreatment. Additionally, the alleviation of inhibition of early rice seedling growth under salt stress by SNP could be modulated by glucose and fructose pretreatment, also the effect of glucose was stronger.

Fructose↗