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Biomedical subjects

Deli Wang

Publications and source records attributed to Deli Wang.

16 recordsLinked to original sources
PubMed2007

High electron mobility InAs nanowire field-effect transistors.

Single-crystal InAs nanowires (NWs) are synthesized using metal-organic chemical vapor deposition (MOCVD) and fabricated into NW field-effect transistors (NWFETs) on a SiO(2)/n(+)-Si substrate with a global n(+)-Si back-gate and sputtered SiO(x)/Au underlap top-gate. For top-gate NWFETs, we have developed a model that allows accurate estimation of characteristic NW parameters, including carrier field-effect mobility and carrier concentration by taking into account series and leakage resistances, interface state capacitance, and top-gate geometry. Both the back-gate and the top-gate NWFETs exhibit room-temperature field-effect mobility as high as 6580 cm(2) V(-1) s(-1), which is the lower-bound value without interface-capacitance correction, and is the highest mobility reported to date in any semiconductor NW.

Arsenicals↗
PubMed2006

Splanchnic oxygen consumption is impaired during severe acute normovolemic anemia in anesthetized humans.

BACKGROUND: In conscious humans, reduction in hemoglobin concentration to 5 g/dl did not produce inadequate systemic oxygenation. However, systemic measures of inadequate oxygenation may not be sufficiently sensitive to detect inadequate oxygenation in individual organs such as splanchnic organs. The authors tested the hypothesis that acute normovolemic anemia to hemoglobin less than 6.0 g/dl in anesthetized humans reduces splanchnic oxygen consumption because of diminished whole body oxygen delivery. METHODS: Elective spine (n = 12) and abdominal (n = 7) surgery patients underwent acute normovolemic anemia to decrease the hemoglobin concentration close to 6.0 g/dl. The authors assessed the development of supply-dependent conditions in systemic and regional vascular beds by two primary measures before and after acute normovolemic anemia: oxygen consumption and surrogate biochemical markers of anaerobic metabolism, including plasma lactate, regional lactate kinetics, and ketone body ratio. RESULTS: When hemoglobin was reduced from 13.6 +/- 1.2 to 5.9 +/- 0.3 g/dl, oxygen supply dependency occurred in the splanchnic and preportal tissues but not at the systemic level. Regional supply dependency was accompanied by biochemical markers of anaerobic metabolism. CONCLUSIONS: In anesthetized humans, a reduction in hemoglobin to 5.9 g/dl by acute normovolemic anemia diminished splanchnic and preportal whole body oxygen delivery and impaired splanchnic and preportal oxygen consumption. This was accompanied by increased plasma levels of regional lactate and an increased beta-hydroxybutyrate-to-acetoacetate ratio. These findings suggest that the risk to the gastrointestinal tract during acute normovolemic anemia may be underestimated.

Adult↗
PubMed2005

A robust two-way semi-linear model for normalization of cDNA microarray data.

BACKGROUND: Normalization is a basic step in microarray data analysis. A proper normalization procedure ensures that the intensity ratios provide meaningful measures of relative expression values. METHODS: We propose a robust semiparametric method in a two-way semi-linear model (TW-SLM) for normalization of cDNA microarray data. This method does not make the usual assumptions underlying some of the existing methods. For example, it does not assume that: (i) the percentage of differentially expressed genes is small; or (ii) the numbers of up- and down-regulated genes are about the same, as required in the LOWESS normalization method. We conduct simulation studies to evaluate the proposed method and use a real data set from a specially designed microarray experiment to compare the performance of the proposed method with that of the LOWESS normalization approach. RESULTS: The simulation results show that the proposed method performs better than the LOWESS normalization method in terms of mean square errors for estimated gene effects. The results of analysis of the real data set also show that the proposed method yields more consistent results between the direct and the indirect comparisons and also can detect more differentially expressed genes than the LOWESS method. CONCLUSIONS: Our simulation studies and the real data example indicate that the proposed robust TW-SLM method works at least as well as the LOWESS method and works better when the underlying assumptions for the LOWESS method are not satisfied. Therefore, it is a powerful alternative to the existing normalization methods.

Algorithms↗
PubMed2003

Nanowire crossbar arrays as address decoders for integrated nanosystems.

The development of strategies for addressing arrays of nanoscale devices is central to the implementation of integrated nanosystems such as biological sensor arrays and nanocomputers. We report a general approach for addressing based on molecular-level modification of crossed semiconductor nanowire field-effect transistor (cNW-FET) arrays, where selective chemical modification of cross points in the arrays enables NW inputs to turn specific FET array elements on and off. The chemically modified cNW-FET arrays function as decoder circuits, exhibit gain, and allow multiplexing and demultiplexing of information. These results provide a step toward the realization of addressable integrated nanosystems in which signals are restored at the nanoscale.

Journal Article↗
PubMed2003

Scalability simulations for nanomemory systems integrated on the molecular scale.

Simulations were performed to assess the prospective performance of a 16 Kbit nanowire-based electronic nanomemory system. Commercial off-the-shelf microcomputer system modeling software was applied to evaluate the operation of an ultra-dense storage array. This array consists of demonstrated experimental non-volatile nanowire diode switches, plus encoder-decoder structures consisting of demonstrated experimental nanowire-based nanotransistors, with nanowire interconnects among all the switching devices. The results of these simulations suggest that a nanomemory of this type can be operated successfully at a density of 10(11) bits/cm(2). Furthermore, modest device alterations and system design alternatives are suggested that might improve the performance and the scalability of the nanomemory array. These simulations represent early steps toward the development of a simulation-based methodology to guide nanoelectronic system design in a manner analogous to the way such methodologies are used to guide microelectronic system design in the silicon industry.

Computer Simulation↗
PubMed2003

[Variations of water-soluble carbohydrate and nitrogen contents in Leymus chinensis and Phragmites communis under different stocking rates].

The variations of the contents of water-soluble carbohydrate and nitrogen in L. chinensis and Ph. communis under different stocking rates were studied by fencing grazing experiment on L. chinensis grassland. The results indicated that the water-soluble carbohydrate content in the base stem of L. chinensis and Ph. communis was the lowest (7.12% and 3.95%, respectively) at the beginning of growth period, and then increased gradually with seasons. There was no significant variation in the content of leaf water-soluble carbohydrate in the grasses. L. chinensis germinated earlier than Ph. communis, resulted in the difference between the water-soluble carbohydrate content in the base stem and the leaf of the grasses at the beginning of the experiment in May. Proper stocking rates were favorable for the increase of water-soluble carbohydrate content, and could accelerate the re-growth capability of the herbage. The nitrogen content was the highest at the beginning of growth period, and then decreased gradually with seasons, which was accorded with their phenology. Proper stocking rates could stimulate the assimilation of nitrogen in soil, and bring it to the ground, which improved the nutrition value of the herbage.

Animal Feed↗
PubMed2003

[Biological evolution and specialization].

There were some disputes about the concept and mechanism of biological evolution. This paper tried to give more explanations on the key concepts. The biological adaptability was distinguished into two different concepts: biological evolution and specialization. The former was defined as the process of biologically gradual evolvement, and the latter was considered as the process of species formation at horizontal development. Moreover, a new conceptual framework was applied to the popular biological theories known by people, and the previous research results or discoveries were explained over again.

Animals↗
PubMed2002

Epitaxial core-shell and core-multishell nanowire heterostructures.

Semiconductor heterostructures with modulated composition and/or doping enable passivation of interfaces and the generation of devices with diverse functions. In this regard, the control of interfaces in nanoscale building blocks with high surface area will be increasingly important in the assembly of electronic and photonic devices. Core-shell heterostructures formed by the growth of crystalline overlayers on nanocrystals offer enhanced emission efficiency, important for various applications. Axial heterostructures have also been formed by a one-dimensional modulation of nanowire composition and doping. However, modulation of the radial composition and doping in nanowire structures has received much less attention than planar and nanocrystal systems. Here we synthesize silicon and germanium core-shell and multishell nanowire heterostructures using a chemical vapour deposition method applicable to a variety of nanoscale materials. Our investigations of the growth of boron-doped silicon shells on intrinsic silicon and silicon-silicon oxide core-shell nanowires indicate that homoepitaxy can be achieved at relatively low temperatures on clean silicon. We also demonstrate the possibility of heteroepitaxial growth of crystalline germanium-silicon and silicon-germanium core-shell structures, in which band-offsets drive hole injection into either germanium core or shell regions. Our synthesis of core-multishell structures, including a high-performance coaxially gated field-effect transistor, indicates the general potential of radial heterostructure growth for the development of nanowire-based devices.

Journal Article↗
PubMed2002

Analysis of hospital use for injury among individuals with mental retardation.

The utilization of hospital facilities for injuries by individuals with mental retardation (MR) was evaluated using a statewide hospital database. In comparison with the general population, persons with MR had a lower proportion of ER visits related to injury (26.5% vs. 30.4%) and were less likely to have multiple ER visits for injuries (Odds Ratio = 0.26, 95% CI 0.10-0.69). When persons with MR were admitted to the hospital for injury, the causes were less likely to be a motor vehicle crash (Odds Ratio = 0.30, 95% CI 0.15-0.62) but more likely to be a fall (Odds Ratio = 1.76, 95% CI 1.19-2.60). In the ER setting, persons with MR were more likely to be seen for poisoning (Odds Ratio = 6.05, 95% CI 2.97-12.32) and falls (Odds Ratio = 1.69, 95% CI 1.24-2.32). Individuals with MR had incurred lower charges per admission and higher charges in the ER, compared to the non-MR group. In general, there were notable differences in the types of injuries and the hospital usage patterns between the group with and without MR.

Accidental Falls↗
PubMed2002

Tobramycin as a pharmacologic tracer to compare airway deposition from nebulizers.

STUDY OBJECTIVE: To assess the utility of inhaled tobramycin as a pharmacologic tracer for comparing lung deposition from a prototypic breath-actuated jet nebulizer connected to an electronic pressure sensor designed to coordinate nebulization with inspiration with that from a continuously operating standard jet nebulizer. DESIGN: Prospective open-label study. SETTING: University-affiliated research center. SUBJECTS: Six healthy adult volunteers. INTERVENTION: All subjects received inhaled tobramycin 80, 160, and 320 mg from each nebulizer during six visits, as well as oral tobramycin 32 mg at a seventh visit to confirm the absence of significant gastrointestinal absorption. During each visit, urine was collected before drug administration and in 12-hour segments throughout the first 48 hours after administration. MEASUREMENTS AND MAIN RESULTS: Lung deposition of tracer after each of the seven treatments was quantified by measuring urinary tobramycin excretion over 48 hours with use of an enzyme-multiplied immunoassay technique. The ratio of tobramycin excreted after breath-actuated nebulization to that after standard nebulization, normalized for dose, was used to compare lung deposition by the two devices. Urinary excretion of tobramycin was linear and proportional to dose for both nebulizers. For every 1 mg of tobramycin that the standard nebulizer deposited into the lungs, the breath-actuated nebulizer deposited 1.22 mg (95% confidence interval 1.04-1.43). CONCLUSIONS: Tobramycin can be used as a pharmacologic tracer for comparison of relative airway deposition by nebulizers.

Administration, Inhalation↗
PubMed2002

[Analysis on competition and coexistence patterns of Aneurolepidium chinense and its main companion species].

In this study, transects were set in areas where Aneurolepidium chinense and its companion species grew together. Competition and coexistence patterns of these species in the ecotone were analyzed using the following measures:frequency distribution, spatial pattern, and pattern intensity. Patterns of A. chinense and its main companion species were diverse. Aggregation was the tactics for A. chinense to defend the foreign species' invading or disperse itself. There existed competition and coexistence between A. chinense and its main companion species. A. chinense and Phragmite communis competed and coexisted through suppression. A. chinense and Kalimeris interifolia coexisted through competition. Hierochloe glabra and Puccinellia tenuiflora competed with A. chinense through clonal growth. Calamagrostis epigeios was suppressed by A. chinense.

China↗
PubMed2002

[Comparison of leaf tissue turnover for Leymus chinensis and Phragmites communis after grazing].

Leaf tissue turnover of Leymus chinensis and Phragmites communis after grazing was studied by application of theory and method of tissue turnover in this paper. The results showed that the number of living leaf of P. communis was larger than that of L. chinensis, but the length of living leaf of L. chinensis was larger than that of P. communis during the whole growth period. Both of the leaf appearance rate and the leaf elongation rate of L. chinensis and P. communis were largest at first, and then they decreased gradually. The rate of leaf wither and leaf senescence were in the converse trend. The leaf lifespan of P. communis was shorter than that of L. chinensis. The velocity of leaf tissue turnover of P. communis was faster than that of L. chinensis. There would be a great loss if the leaf tissue of L. chinensis were not used in time. The quality of grasslands could be improved by different utilization ways and periods.

Animals↗
PubMed2002

[Perspectives in researches on grassland ecology for the early 21st century in China].

Grassland degeneration is a prominent problem in China. More in-depth studies should be carried out on the key problem--grassland degeneration for Chinese grassland ecologists in the early 21st century. Some hot research fields were restoration ecology, interface ecology, grazing ecology, health diagnoses and evaluation for grasslands. Among them, restoration ecology was the foundation for restoring degenerative grasslands; interface ecology involved with the point of contact for analyzing degenerative grasslands; grazing ecology was the effective way to control degenerative grasslands; diagnoses of grassland health benefited accurately appraising degenerative levels of grasslands; and evaluation for grassland was also considered as an estimation on services and benefits of grassland ecosystems.

China↗
PubMed2002

[A comparative study on photosynthesis and transpiration of Kelimeris integrifolia in summer and autumn on Songnen grasslands of China].

The diurnal changes in photosynthesis and transpiration of Kelimeris integrifolia in Summer and Autumn on Songnen grasslands were characterized as a two-peak curve, but with some differences between two seasons. It was shown that environmental conditions and plant internal factors had a strong effects on plant photosynthesis and transpiration. The net photosynthetic and transpiration rates of the leaves were positively correlated to photosynthetically active radiation (P < 0.01), and negatively correlated to stomatal resistance as well as intercellular CO2 concentration (P < 0.05). The transpiration rate was positively correlated to leaf temperature and water saturation deficit of the air. Among the above factors, photosynthesis active radiation was the dominant factor, and stomatal resistance also played an important role in plant photosynthesis and transpiration.

China↗
PubMed2001

Biosensors from conjugated polyelectrolyte complexes.

A charge neutral complex (CNC) was formed in aqueous solution by combining an orange light emitting anionic conjugated polyelectrolyte and a saturated cationic polyelectrolyte at a 1:1 ratio (per repeat unit). Photoluminescence (PL) from the CNC can be quenched by both the negatively charged dinitrophenol (DNP) derivative, (DNP-BS(-)), and positively charged methyl viologen (MV(2+)). Use of the CNC minimizes nonspecific interactions (which modify the PL) between conjugated polyelectrolytes and biopolymers. Quenching of the PL from the CNC by the DNP derivative and specific unquenching on addition of anti-DNP antibody (anti-DNP IgG) were observed. Thus, biosensing of the anti-DNP IgG was demonstrated.

Animals↗