Biomedical subjects

Ning Zhu

Publications and source records attributed to Ning Zhu.

14 recordsLinked to original sources

PubMed2006

Study of biodegradable and self-expandable PLLA helical biliary stent in vivo and in vitro.

Biodegradable stents have advantages for the treatment of benign and malignant biliary stricture, especially eliminating the need for stent removal. In our present work, helical poly-l-lactic acids (PLLA) stent was fabricated and evaluated in vivo and in vitro. For in vivo study, bile duct injury canine models were made by transection of common bile ducts. Duct to duct anastomosis was done with helical PLLA biodegradable stents. Scanning electron microscopy (SEM) and histopathology were performed after three months. For In vitro study, sludge attachment assessment was performed. Polyethylene (PE) and PLLA membranes were immersed in human bile for two months. The samples were taken out and characterized by SEM. Self-expanding property of the helical stent was tested in 37 degrees Celsius water. The results demonstrate that the biodegradable stent had not only good biocompatibility, but also self-clearing effect to clear the attached sludge away. The self-expanding property facilitated stent implantation and also suggested possibility to be implanted endoscopically.

Absorbable Implants↗

PubMed2006

Classification of adaptive memetic algorithms: a comparative study.

Adaptation of parameters and operators represents one of the recent most important and promising areas of research in evolutionary computations; it is a form of designing self-configuring algorithms that acclimatize to suit the problem in hand. Here, our interests are on a recent breed of hybrid evolutionary algorithms typically known as adaptive memetic algorithms (MAs). One unique feature of adaptive MAs is the choice of local search methods or memes and recent studies have shown that this choice significantly affects the performances of problem searches. In this paper, we present a classification of memes adaptation in adaptive MAs on the basis of the mechanism used and the level of historical knowledge on the memes employed. Then the asymptotic convergence properties of the adaptive MAs considered are analyzed according to the classification. Subsequently, empirical studies on representatives of adaptive MAs for different type-level meme adaptations using continuous benchmark problems indicate that global-level adaptive MAs exhibit better search performances. Finally we conclude with some promising research directions in the area.

Algorithms↗

PubMed2006

Effects of surface roughness on the performance of an etched diffraction grating demultiplexer.

The fabrication tolerance of surface roughness on the performance [such as the insertion loss, the polarization-dependent loss (PDL), and the chromatic dispersion] of an etched diffraction grating demultiplexer is analyzed by using an accurate method of moments. The results show that both the insertion loss and the chromatic dispersion rapidly increase as the roughness of the grating facets increases. Appropriate residual roughness of the shaded facets can reduce the PDL of the demultiplexer, and the mechanism for the existence of an optimal residual roughness is explained.

Journal Article↗

PubMed2006

Sidelobe suppression design of etched diffraction grating demultiplexers using optimized air trenches in front of each output waveguide.

An etched diffraction grating (EDG) demultiplexer with high sidelobe suppression is designed. Sidelobes resulting from two adjacent wavelengths are suppressed by etching two optimized rectangular air trenches in front of each output waveguide that can induce large resonance loss in the adjacent wavelength but have little influence on the operational wavelength. The designed EDG demultiplexer can suppress crosstalk to less than 50 dB in theory.

Journal Article↗

PubMed2005

Alternative splicing of Slo channel gene programmed by estrogen, progesterone and pregnancy.

STREX alternative-exon adds to Slo channel a phosphorylation sequence that can invert protein kinase A (PKA) regulation from excitatory to inhibitory. Because pregnancy switches Slo responsiveness to PKA from inhibitory to excitatory, we hypothesized that STREX expression diminishes with pregnancy and is regulated by sex hormones. Different from total-rSlo, which is elevated around mid-pregnancy and decreases at term, STREX transcripts progressively decreased with pregnancy near 80% at term. STREX downregulation was mimicked by estrogen, and opposed by estrogen-receptor antagonist ICI 182,780 or progesterone (Pg). The regulation of STREX splicing directed by estrogen and Pg provides a mechanism for Slo's PKA-related phenotypic alteration with pregnancy.

Alternative Splicing↗

PubMed2005

Genotyping the -6A/G functional polymorphism in the core promoter region of angiotensinogen gene by microchip electrophoresis.

Angiotensinogen (AGT) gene has been regarded as one of the candidate genes for essential hypertension. In our study, the role of AGT gene as a putatively predisposing gene for hypertension was evaluated by genotyping a A (-6) G polymorphism in the core promoter region in 123 patients with essential hypertension and 103 healthy controls. A microchip electrophoresis method coupled with polymorphism chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay was used for genotyping the A (-6) G single-nucleotide polymorphism. The separation and detection of the digested PCR amplicons were completed just in 280 s or less. The genotype frequency fulfilled the criteria of the Hardy-Weinbery equilibrium (X2 = 3.067, P > 0.05). The results showed a higher frequency of the -6 A allele (0.70) in the normotensive subjects, which is higher than those reported in Germany (0.47) and Czech (0.40) populations, but similar to that found in Japanese populations (0.73). The frequencies of genotype AA, AG, and GG were 0.46, 0.49, and 0.05 in hypertensive subjects, and 0.44, 0.53, and 0.03 in control subjects. There is no significant difference in the distributions of the genotype and allele between the two groups (X2 = 0.88, P > 0.05; X2 = 0.024, P > 0.05). These findings differ from some of the results obtained in other ethnic groups, indicating the potential importance of ethnic origin in the assessment of genetic risk identifiers for a complex disease.

Aged↗

PubMed2005

Analysis of the loss resulting from point defects for an etched diffraction grating demultiplexer by using the method of moments.

An effective method for analyzing the effect of point defects (e.g., dust grains and air bubbles) on an etched diffraction grating demultiplexer is presented by using the method of moments. This method leads to a deep insight into the influence of point defects on the loss of the demultiplexer. Numerical results show that strong resonance losses can be produced at some special point defects and incident light.

Journal Article↗

PubMed2005

[Application of 3S techniques in ecological landscape planning of Harbin suburb].

With the image data (SPOT), soil utilization map (1:50000) and other related materials of Harbin, and under the support of GIS, RS and GPS techniques, this paper obtained the landscape pattern of Harbin suburb and the Digital Elevation Model (DEM) of Harbin. Indices including mean patch area, landscape dominance, mean slope, mean altitude, and fragmentation degree were selected and synthetically analyzed, with the ecological landscape planning made by DEM model. The results showed that 3S techniques could help to decide typical landscape types. The landscape type database was established, and the landscape type thematic map was generated, with land use status and landscape distribution, physiognomy, and land use types combined. The ecological landscape planning was described in large scale with the image data and DEM combined, and the landscape structure of Harbin suburb was reflected directly with the ecological landscape planning and DEM combined, which improved the ecological function in this region, and provided scientific bases to the healthy development in urban-rural integration area.

China↗

PubMed2004

Neurotrophin-independent attraction of growing sensory and motor axons towards developing Xenopus limb buds in vitro.

The mechanisms for directing axons to their targets in developing limbs remain largely unknown though recent studies in mice have demonstrated the importance of neurotrophins in this process. We now report that in co-cultures of larval Xenopus laevis limb buds with spinal cords and dorsal root ganglia of Xenopus and axolotl (Ambystoma mexicanum) axons grow directly to the limb buds over distances of up to 800 microm and in particular to sheets of epidermal cells which migrate away from the limb buds and also tail segments in culture. This directed axonal growth persists in the presence of trk-IgG chimeras, which sequester neurotrophins, and k252a, which blocks their actions mediated via trk receptors. These findings indicate that developing limb buds in Xenopus release diffusible factors other than neurotrophins, able to attract growth of sensory and motor axons over long distances.

Ambystoma mexicanum↗

PubMed2004

[Studies on the preparation technology of beta-cyclodextrin inclusion compound for chuanxiong volatile oil extracted with CO2 supercritical fluid].

OBJECTIVE: To explore the preparation technology of beta-cyclodextrin inclusion compound for chuanxiong volatile oil. METHOD: Orthogonal test was used to evaluate the influence of the 4 factors, including the proportion of volatile oil to beta-cyclodextrin, the mode of mixing, inclusion temperature and mixing time. RESULT: The best inclusion condition is the proportion of volatile oil to beta-cyclodextrin 1:9, the mode of mixing grinding, inclusion temperature 60 degrees C and inclusion time 90 min. CONCLUSION: The best inclusion technology of chuanxiong volatile oil is confirmed.

Carbon Dioxide↗

PubMed2003

[A survey of the level of AIDS knowledge among people concerned in Nanjing City].

OBJECTIVES: To investigate the level of AIDS knowledge among people concerned in Nanjing city in order to provide scientific evidence and constructive suggestions for the government to formulate relevant policies for AIDS control. METHODS: Three sets of questionnaires on AIDS knowledge were designed, the scores calculated, and the results evaluated. RESULTS: Of the 2,500 questionnaires issued to 4 different groups of people, 2,436 were collected back with effective answers, 991 from medical and health-related workers with the mean score of 58, 473 from college students with the mean score of 39.9, 524 from common city residents with the mean score of 42.3, and 448 from those working in high risk environment with the mean score of 47. CONCLUSIONS: The level of AIDS knowledge among people concerned in Nanjing city was far below the requirement of the nation, especially among medical and health-related workers. Efforts must be made to raise the level of AIDS knowledge of people concerned so as to enhance the prevention and treatment of the disease.

Acquired Immunodeficiency Syndrome↗

PubMed2003

[Analysis on instantaneous spatial pattern of thermal force field in Harbin].

The spatial pattern of urban thermal force field is not only the dominant content in assessing city ecological environment, but also an important base for city green system planning. The status of spatial pattern of thermal force field in Harbin was analyzed with RS and GIS techniques. Based on the instantaneous radiation temperature of the land surfaces in the city when the TM image was sensed remotely, all the patches were divided into 3 levels, i.e., low radiation temperature (< 10 degrees C), middle radiation temperature (10-22 degrees C), and high radiation temperature of the land surfaces (22-31 degrees C). The patches with high radiation temperature accounted for 61%, those with low radiation temperature accounted for 17%, and those with middle radiation temperature accounted for 22%. 7018 patches (12,252 hm2 in total) with super-thermal radiation (> 28 degrees C) were uneven in their areas. The biggest area in these patches was 1489 hm2, and the smallest one was 0.72 hm2. The proportion of the patches with an area less than 1 hm2, between 1-5 hm2, and more than 5 hm2 was 95.02%, 3.46%, and 1.58%, respectively. There were 3 types of spatial patterns of the super-thermal radiation patches, i.e., round form (the average radiation temperature was 30.8 degrees C), ring form (the average radiation temperature was 27 degrees C), and pieces form (the average radiation temperature was 24.7 degrees C). Daowai District and Daoli District were round form, districts along the ring routes of railway in the city were ring form, and Nangang District and Dongli District were pieces form. Some advices to resolve the problem of 'heat island effect' influenced by the factors including greenland covering rate, greenland area and building dimension were discussed.

City Planning↗

PubMed2002

[Ecological functions of green land system in Harbin].

Patch and strip green lands in Harbin with plantation structure of tree + shrub + herb, tree + herb, shrub + herb, tree, shrub, and lawn were selected as studied objects. Through testing PAR, temperature (t), relative humidity (RH), and CO2 concentration in the center and outside of the selected green lands, the ecological functions of the green lands on regulating city microclimate were analyzed. The results showed that except lawn, patch green lands had the function of shading. Green lands with plantation structure of tree + shrub + herb, tree, tree + herb, and shrub had greater effects on lowering temperature, increasing humidity, and adjusting CO2 concentration than that of lawn. Strip green lands also had certain effects on shading, lowering temperature, increasing humidity, and adjusting CO2 concentration. Among different plantation structures of stripe green lands, shrub had the best effect on shading, and tree + shrub had the best effects on lowering temperature, increasing humidity, and adjusting CO2 concentration. The ecological functions of patch green lands were better than those of strip green lands with the same plantation structure, and green lands with multistoried structure had greater ecological effects than those with single layer.

Carbon Dioxide↗

PubMed2002

[Dust removal effect of urban tree species in Harbin].

Dust removal by plants was proposed as an important basis of designing urban green space system for future urbanization. Dust removal measurement and leaf surface electron-microscopic scanning were taken for 28 tree species in Harbin city. The results showed that there were obviously different effects of dust removal among different tree species. Picea koraiensis and Juniperus rigida were the ideal conifers for dust removal, and their dust removal abilities were 5.7 g.m-2 and 4.4 g.m-2 after 4 weeks, respectively. Populus alba x berolinensis, Lonicera maackii, and Prunus maackii were the ideal deciduous tree species, and their dust removal abilities were respectively 1.9 g.m-2, 2.0 g.m-2, and 2.45 g.m-2 after 2 weeks. Observation under electronic microscope showed that tree species, having deep channels or dense hair on leaf surface had greater effects of dust removal, while tree species, which had strumose projections on leaf surface, had weaker effects. Different modes of dust removal by plants were also discussed.

Carbon Dioxide↗