Biomedical subjects

Z L Wang

Publications and source records attributed to Z L Wang.

At least 19 recordsLinked to original sources

PubMed2006

Synthesis and electrical transport of single-crystal NH4V3O8 nanobelts.

Monoclinic NH(4)V(3)O(8) single-crystalline nanobelts with widths of 80-180 nm, thicknesses of 50-100 nm, and lengths up to tens of micrometers have been synthesized at large scale in an ammonium metavanadate solution by a templates/catalysts-free route. Such nanobelts grow along the direction of [010]. The individual NH(4)V(3)O(8) nanobelt exhibits nonlinear, symmetric current/voltage (I/V) characteristics, with a conductivity of 0.1-1 S/cm at room temperature and a dielectric constant of approximately 130. The dominant conduction mechanism is based on small polaron hopping due to ohmic mechanism at low electric field below 249 V/cm due to Schottky emission at medium electric field between 249 and 600 V/cm and due to the Poole-Frenkel emission mechanism at high field above 600 V/cm.

Catalysis↗

PubMed2006

Size-manipulable synthesis of single-crystalline BaMnO3 and BaTi1/2Mn1/2O3 nanorods/nanowires.

We report a size-manipulable synthesis of single-crystalline nanorods/nanowires of barium manganite (BaMnO(3)) and barium titanium manganite (BaTi(1/2)Mn(1/2)O(3)) by using the composite-hydroxide-mediated approach. The synthesis cleanly yields nanorods with a hexagonal perovskite structure. Typical nanorods have widths ranging between 50 and 100 nm, and the lengths can be easily controlled by time and temperature or by adding a small amount of water during the synthesis process. Resistance measurement shows that a phase transition happened at 58 K on BaMnO(3). The photoluminescence spectrum of BaTi(1/2)Mn(1/2)O(3) presents two emission peaks at wavelengths of 465 and 593 nm, corresponding to blue and green fluorescence. The ability to synthesize nanorod manganites of a desired length should enable detailed investigations of the size-dependent evolution of magnetism, magnetoresistance, nanoscale phase separation, and realization of a nanodevice of magnetic sensors.

Barium Compounds↗

PubMed2006

Heterogeneous meshing and biomechanical modeling of human spine.

We aim to develop a patient-specific biomechanical model of human spine for the purpose of surgical training and planning. In this paper, we describe the development of a finite-element model of the spine from the VHD Male Data. The finite-element spine model comprises volumetric elements suitable for deformation and other finite-element analysis using ABAQUS. The mesh generation solution accepts segmented radiological slices as input, and outputs three-dimensional (3D) volumetric finite element meshes that are ABAQUS compliant. The proposed mesh generation method first uses a grid plane to divide the contours of the anatomical boundaries and its inclusions into discrete meshes. A grid frame is then built to connect the grid planes between any two adjacent planes using a novel scheme. The meshes produced consist of brick elements in the interior of the contours and with tetrahedral and wedge elements at the boundaries. The nodal points are classified according to their materials and hence, elements can be assigned different properties. The resultant spine model comprises a detailed model of the 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, and S1. Each of the vertebrae and intervertebral disc has between 1200 and 6000 elements, and approximately 1200 elements, respectively. The accuracy of the resultant VHD finite element spine model was good based on visual comparison of volume-rendered images of the original CT data, and has been used in a computational analysis involving needle insertion and static deformation. We also compared the mesh generated using our method against two automatically generated models; one consists of purely tetrahedral elements and the other hexahedral elements.

Adult↗

PubMed2006

Prion protein gene (PRNP) polymorphisms in Xinjiang local sheep breeds in China.

Amino acid polymorphisms of the prion protein (PrP) gene (PRNP), particularly those occurring at codons 136, 154, and 171 have a significant influence on scrapie pathogenesis in many sheep breeds. We isolated blood samples from 222 sheep representing the eight main local sheep breeds in the Xinjiang Autonomous Region, the territory with the most abundant local sheep breeds in China, to identify the PRNP polymorphisms and to determine whether these breeds were at risk for developing scrapie. A new PRNP polymorphism encoding either glycine (G) or arginine (R) at codon 85 as well as eight previously reported polymorphisms at codons 101, 112, 127, 141, 146, 154, 171, and 189 in other sheep breeds were detected. Interestingly, the alanine (A)/V polymorphism at codon 136 was not observed in this study, all sheep being homozygous for A at this position. While the previously identified polymorphism of argine (R) or histidine (H) at codon 154 was detected, the H polymorphism was rare (2.25%). Four polymorphisms at codon 171 encoding glutamine (Q), R, H, or lysine (K) were detected. The predominant ARQ allele occurred at a high frequency of 77.48%, suggesting an increased risk of scrapie in Xinjiang Autonomous Region.

Alleles↗

PubMed2006

Transmission electron microscopy and theoretical analysis of AuCu nanoparticles: atomic distribution and dynamic behavior.

Though the application of bimetallic nanoparticles is becoming increasingly important, the local atomistic structure of such alloyed particles, which is critical for tailoring their properties, is not yet very clearly understood. In this work, we present detailed study on the atomistic structure of Au-Cu nanoparticles so as to determine their most stable configurations and the conditions for obtaining clusters of different structural variants. The dynamic behavior of these nanoparticles upon local heating is investigated. AuCu nanoparticles are characterized by high resolution transmission electron microscopy (HRTEM) and energy filtering elemental composition mapping (EFECM), which allowed us to study the internal structure and the elemental distribution in the particles. Quantum mechanical approaches and classic molecular dynamics methods are applied to model the structure and to determine the lowest energy configurations, the corresponding electronic structures, and understand structural transition of clusters upon heating, supported by experimental evidences. Our theoretical results demonstrate only the core/shell bimetallic structure have negative heat of formation, both for decahedra and octahedral, and energetically favoring core/shell structure is with Au covering the core of Cu, whose reverse core/shell structure is not stable and may transform back at a certain temperature. Experimental evidences corroborate these structures and their structural changes upon heating, demonstrating the possibility to manipulate the structure of such bimetallic nanoparticles using extra stimulating energy, which is in accordance with the calculated coherence energy proportions between the different configurations.

Alloys↗

PubMed2006

A dry powder inhaler with reduced mouth-throat deposition.

A novel, compact, and highly efficient dry powder inhaler (DPI) with low mouth-throat deposition is described. The performance of this DPI was evaluated by measuring both (1) the total aerosol deposition in and distal to an idealized mouth-throat cast and (2) the fine particle fraction (FPF) using a standard Mark II Anderson impactor. Ultraviolet (UV) spectroscopy techniques were used in the aerosol deposition measurements. Two inhalation aerosol powders, namely budesonide (extracted from a Pulmicort/Turbuhaler multi-dose device, 200 microg/dose) and ciprofloxacin + lipid + lactose (in-house), were dispersed by the DPI at a steady inhalation flow rate of 60 L/min. The newly developed DPI had a total aerosol delivery distal to the mouth-throat cast of 50.5% +/- 3.04% and 69.7% +/- 1.5% for the budesonide and ciprofloxacin + lipid + lactose aerosols, respectively. This is a significant improvement over the Turbuhaler original device delivery of 34.5% +/- 5.2%, particularly considering that in vitro mouth-throat deposition dropped from 27.5% +/- 5.4% with the budesonide Turbuhaler to 11.0% +/- 3.5% with the present inhaler. The different lung deliveries from the same inhaler for the two formulations above also confirm that the overall performance of an inhaler is optimizable via powder formulations.

Administration, Inhalation↗

PubMed2006

Sol-gel fabrication and photoluminescence properties of SiO2 @ Gd2O3:Eu3+ core-shell particles.

A uniform nanolayer of europium-doped Gd2O3 was coated on the surface of preformed submicron silica spheres by a Pechini sol-gel process. The resulted SiO2 @ Gd2O3:Eu3+ core-shell structured phosphors were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays. The XRD results show that the Gd2O3:Eu3+ layers start to crystallize on the SiO2 spheres after annealing at 400 degrees C and the crystallinity increases with raising the annealing temperature. The core-shell phosphors possess perfect spherical shape with narrow size distribution (average size: 640 nm) and non-agglomeration. The thickness of the Gd2O3:Eu3+ shells on the SiO2 cores can be adjusted by changing the deposition cycles (70 nm for three deposition cycles). Under short UV excitation, the obtained SiO2@Gd2O3:Eu3+ particles show a strong red emission with 5D0-7F2 (610 nm) of Eu3+ as the most prominent group. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

Crystallization↗

PubMed2006

[Preparation of monoclonal antibodies against West Nile virus envelope protein domain.].

BACKGROUND: To prepare monoclonal antibodies against West Nile virus (WNV) envelope protein domain. METHODS: BALB/c mice were immunized with recombinant antigen of West Nile virus envelope protein domain, and the spleen cells of the mice were used to prepare the monoclonal antibodies (McAb) by hybridoma technique. RESULTS: Three hybridoma cell strains secreting McAbs against WNV envelope protein domain, designated as 4F7, 6H3 and 8E4, respectively, were obtained and were identified by indirect enzyme linked immunosorbent assay (ELISA), they belonged to IgG1, IgG1 and Ig2a, respectively. Two epitopes of envelope protein domain were determined, among them, 4F7 and 6H3 were against the same epitope and 8E4 to another one. CONCLUSIONS: The results of indirect ELISA, Western blot and indirect immunofluorescence experiment indicated that these three McAbs were specific for West Nile virus envelope protein domain and did not cross-react with Japanese encephalitis virus and other viruses, so they can be used for specific detection of West Nile virus.

Animals↗

PubMed2005

Pharmacological studies of the large-scaled purified genistein from Huaijiao (Sophora japonica-Leguminosae) on anti-osteoporosis.

In this report, we used genistein that was extracted from a Chinese herbal medicine Huaijiao (Sophora japonica-Leguminosae) to evaluate its pharmacological function on anti-osteoporosis. This genistein is purified in a large-scale production from Huaijiao by a state-of-art method as described by Tian et al. [2004. The preparation of genistein and LC-MS/MS on-line analysis. Drug Devel. Res. 61, 6-12]. Chemical structure of the isolated genistein was examined by using various techniques including nuclear magnetic resonant spectrum, infrared absorption spectrum, ultraviolet absorption spectrum and mass spectrum, and was proved to be identical to those purified from soybean in a small scale as previously reported. We randomly divided female SD rats into 6 groups, including control, ovariectomized model, Nilestriol-treated, and three level of dosages of genistein-treated. We evaluated the pharmacological effects of genistein against osteoporosis by measuring the bone density of femur and bone mineral group including calcium, phosphorous, and magnesium. The consequences of genistein treatment on bone histology and morphology were also determined by measuring the trabcular area, thickness and number. Our results indicated that treatment with a 4.5 or 9 mg/kg dosage of genistein could also prevent osteoporosis significantly at the 4th week after treatment. In comparison with the anti-osteoporosis effects of soybean genistein, the genistein extracted from Huaijiao has the same beneficial effect on anti-osteoporosis.

Animals↗

PubMed2005

Seven-nanometer hexagonal close packed cobalt nanocrystals for high-temperature magnetic applications through a novel annealing process.

Seven-nanometer cobalt nanocrystals are synthesized by colloidal chemistry. Gentle annealing induces a direct structural transition from a low crystalline state to the hexagonal close packed (hcp) phase without changing the size, size distribution, and the lauric acid passivating layer. The hcp structured nanocrystals can be easily redispersed in solvent for further application and processing. We found that the magnetization at saturation and the magnetic anisotropy are strongly modified through the annealing process. Monolayer self-assembly of the hcp cobalt nanocrystals is obtained, and due to the dipolar interaction, ferromagnetic behavior close to room temperature has been observed. This work demonstrates a novel approach for obtaining small size hcp structured cobalt magnetic nanocrystals for many technological applications.

Journal Article↗

PubMed2005

Synthesis of bimetallic nanoshells by an improved electroless plating method.

In the Letter, we demonstrate an improved electroless plating method for the synthesis of bimetallic shell particles. The procedure involves a combination of surface reaction, seeding growth, and removal of supporting cores. We modified ammonical AgNO3 in ethanol with a controlled amount of HCHO in the seeding process and a uniform and relatively dense coverage of silver nanoparticle seeds on colloid cores was achieved. Following the second kind of metal plating, we extended this method to prepare continuous bimetallic core-shell and hollow particles with a submicrometer diameter. The morphologies of the bimetallic Cu/Ag and Pt/Ag particles were studied with transmission electron microscopy and scanning electron microscopy, and their crystallinity and chemical composition were confirmed by X-ray diffraction. The prepared materials may be of applied value in areas such as catalysis, optics, and plasmonics.

Journal Article↗

PubMed2005

An X-ray nanodiffraction technique for structural characterization of individual nanomaterials.

An X-ray micro/nanodiffraction technique that allows structural characterization of individual nanomaterials has been developed at an insertion-device beamline of the Advanced Photon Source. Using the extremely high brightness of the third-generation synchrotron radiation source and advanced high-resolution high-energy zone-plate focusing optics, X-rays of energies from 6 to 12 keV have been focused into a spot smaller than 200 nm with a photon density gain of more than 50,000 so that significant photon flux can be intercepted by a nanoscale material to generate a measurable diffraction signal for structural characterization. This paper describes the instrumentation of the technique and discusses the application of the technique to studies of tin oxide nanobelts.

Journal Article↗

PubMed2005

Computational biomechanical modelling of the lumbar spine using marching-cubes surface smoothened finite element voxel meshing.

There is a need for the development of finite element (FE) models based on medical datasets, such as magnetic resonance imaging and computerized tomography in computation biomechanics. Direct conversion of graphic voxels to FE elements is a commonly used method for the generation of FE models. However, conventional voxel-based methods tend to produce models with jagged surfaces. This is a consequence of the inherent characteristics of voxel elements; such a model is unable to capture the geometries of anatomical structures satisfactorily. We have developed a robust technique for the automatic generation of voxel-based patient-specific FE models. Our approach features a novel tetrahedronization scheme that incorporates marching-cubes surface smoothing together with a smooth-distortion factor (SDF). The models conform to the actual geometries of anatomical structures of a lumbar spine segment (L3). The resultant finite element analysis (FEA) at the surfaces is more accurate compared to the use of conventional voxel-based generated FE models. In general, models produced by our method were superior compared to that obtained using the commercial software ScanFE.

Biomechanical Phenomena↗

PubMed2005

Dental fluorosis in primary teeth: a study in rural schoolchildren in Shaanxi Province, China.

OBJECTIVE: The aim of this study was to assess the prevalence and severity of fluorosis in the primary dentition of 7-8-year-old Chinese schoolchildren in areas with fluoride concentrations in the drinking water ranging from 0.35 to 7.6 mg L-). SUBJECTS AND METHODS: Four hundred and seventy-two children from 13 different schools were divided into four groups according to the fluoride concentration of the drinking water: (A) <or=1.0 mg L-1; (B) 1.1-2.0 mg L-1; (C) 2.1-3.8 mg L-1; and (D) 7.6 mg L-1. Clinical examinations were made under field conditions, and dental fluorosis on the buccal surfaces of all teeth was recorded using the Thylstrup-Fejerskov Index (TFI). RESULTS: The prevalence of dental fluorosis in primary teeth varied from 6.2% to 96.6% according to the fluoride concentration of the drinking water. The differences of median of TFI scores between all groups were statistically significant (P<0.001) except for groups B and C. No statistically significant difference in the severity of dental fluorosis was observed between genders. The second primary molars were most severely affected by dental fluorosis. Disregarding group A, TFI scores between 3 and 4 were most frequently recorded. Dental fluorosis was symmetrically distributed in both jaws. CONCLUSION: Dental fluorosis is prevalent in the primary teeth of children living in areas supplied with drinking water with fluoride concentrations higher than 1.0 mg L-1. The primary teeth may act as biomarkers of fluoride exposure. The examination of primary teeth may give an early warning of this condition, and thus, provide a basis for intervention to prevent dental fluorosis in the permanent teeth.

Age Distribution↗

PubMed2004

Preparation of metallodielectric composite particles with multishell structure.

In this article, we demonstrated the synthesis of metallodielectric composite particles comprising a metal shell on a dielectric core and an outer coating of an insulating dielectric layer by depositing silver on silica supporting cores followed by coating of titania. A combination of surface reaction and surface seeding techniques is exploited for the formation of a complete silver shell on silica spheres. The additional outer coating of titania on silver shell particles is then performed by hydrolyzing tetra-n-butyl titanate in ethanol at room temperature. The morphologies of silver shells and titania coating are studied with electron microscopy, and their existences are confirmed with X-ray diffraction and energy-dispersive X-ray measurement.

Journal Article↗

PubMed2003

Molecular tagging and genetic mapping of the disease resistance gene RppQ to southern corn rust.

Southern corn rust (SCR), Puccinia polysora Underw, is a destructive disease in maize ( Zea mays L.). Inbred line Qi319 is highly resistant to SCR. Results from the inoculation test and genetic analysis of SCR in five F(2) populations and five BC(1)F(1 )populations derived from resistant parent Qi319 clearly indicate that the resistance to SCR in Qi319 is controlled by a single dominant resistant gene, which was named RppQ. Simple sequence repeat (SSR) analysis was carried out in an F(2) population derived from the cross "Qi319x340". Twenty SSR primer pairs evenly distributed on chromosome10 were screened at first. Out of them, two primer pairs, phi118 and phi 041, showed linkage with SCR resistance. Based on this result, eight new SSR primer pairs surrounding the region of primers phi118 and phi 041 were selected and further tested regarding their linkage relation with RppQ. Results indicated that SSR markers umc1,318 and umc 2,018 were linked to RppQ with a genetic distance of 4.76 and 14.59 cM, respectively. On the other side of RppQ, beyond SSR markers phi 041 and phi118, another SSR marker umc1,293 was linked to RppQ with a genetic distance of 3.78 cM. Because the five linkage SSR markers (phi118, phi 041, umc1,318, umc 2,018 and umc1,293) are all located on chromosome 10, the RppQ gene should also be located on chromosome 10. In order to fine map the RppQ gene, AFLP (amplified fragment length polymorphism) analysis was carried out. A total 54 AFLP primer combinations were analyzed; one AFLP marker, AF1, from the amplification products of primer combination E-AGC/M-CAA, showed linkage with the RppQ gene in a genetic distance of 3.34 cM. Finally the RppQ gene was mapped on the short arm of chromosome 10 between SSR markers phi 041 and AFLP marker AF1 with a genetic distance of 2.45 and 3.34 cM respectively.

Basidiomycota↗

PubMed2003

Induced growth of asymmetric nanocantilever arrays on polar surfaces.

We report that the Zn-terminated ZnO (0001) polar surface is chemically active and the oxygen-terminated (000(-)1) polar surface is inert in the growth of nanocantilever arrays. Longer and wider "comblike" nanocantilever arrays are grown from the (0001)-Zn surface, which is suggested to be a self-catalyzed process due to the enrichment of Zn at the growth front. The chemically inactive (0001;)-O surface typically does not initiate any growth, but controlling experimental conditions could lead to the growth of shorter and narrower nanocantilevers from the intersections between (000(-)1)-O with +/- (01(-)10) surfaces.

Journal Article↗

PubMed2003

Optical properties of inverted opal photonic band gap crystals with stacking disorder.

We present a detailed study of the effect of planar stacking disorder on optical properties of inverted opal photonic crystals. Systems with periodic stacking sequences are first studied that include face centered cubic, hexagonal close-packed, and doubly hexagonal close-packed photonic crystals. For the structures with periodic stacking order, we evaluate the band structure followed by calculation of transmission spectrum along the direction perpendicular to the hexagonal close-packing plane of the structures. Inverted opal photonic crystals with random stacking sequences are then studied by calculating average transmittance of the photonic crystal slabs over various random stacking configurations. The position and width of the lowest stop gap along the direction normal to the hexagonal close-packing plane is found to be invariant, regardless of the stacking sequence in the photonic crystal. We show how the propagation properties at higher frequencies are affected by the stacking configurations (both periodic and disordered stacking sequences), particularly those near the edges of the absolute band gap. The obtained results are directly relevant to transmission/reflection experiments on inverted opal photonic crystals with complete band gap.

Journal Article↗