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Baer MT, Huang N, Gibson FC. Scavenger receptor A is expressed by macrophages in response to Porphyromonas gingivalis, and participates in TNF-alpha expression. ACTA ACUST UNITED AC 2010; 24:456-63. [PMID: 19832797 DOI: 10.1111/j.1399-302x.2009.00538.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
INTRODUCTION Porphyromonas gingivalis is a periodontopathic bacterium closely associated with generalized aggressive periodontal disease. Pattern recognition receptors (PRRs) participate in host response to this organism. It is likely that PRRs not previously recognized as part of the host response to P. gingivalis also participate in host response to this organism. METHODS AND RESULTS Employing qRT-PCR, we observed increased msr1 gene expression at 2, 6, and 24 h of culture with P. gingivalis strain 381. Flow cytometry revealed increased surface expression of SR-A protein by the 24 h time point. Macrophages cultured with an attachment impaired P. gingivalis fimA- mutant (DPG3) expressed intermediate levels of SR-A expression. Heat-killed P. gingivalis stimulated SR-A expression similar to live bacteria, and purified P. gingivalis capsular polysaccharide stimulated macrophage SR-A expression, indicating that live whole organisms are not necessary for SR-A protein expression in macrophage response. As SR-A is known to play a role in lipid uptake by macrophages, we tested the ability of low-density lipoprotein (LDL) to influence the SR-A response of macrophages to P. gingivalis, and observed no effect of LDL on P. gingivalis-elicited SR-A expression. Lastly, we observed that SR-A knockout (SR-A(-/-)) mouse macrophages produced significantly more tumor necrosis factor (TNF)-alpha than wild type mouse macrophages cultured with P. gingivalis. CONCLUSION These data identify that SR-A is expressed by macrophages in response to P. gingivalis, and support that this molecule plays a role in TNF-alpha production by macrophages to this organism.
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Davidson P, Driscoll A, Huang N, Aho Z, Atherton J, Hood S, Krum H, Sindone A, Stewart S. Best Practice Multidisciplinary Care for Chronic Heart Failure in Australia. Heart Lung Circ 2010. [DOI: 10.1016/j.hlc.2010.06.818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Yang J, Huang N, Du Q. A non-uniform expansion mechanical safety model of the stent. J Med Eng Technol 2009; 33:525-31. [PMID: 19517292 DOI: 10.1080/07434610902744082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Stents have a serial unstable structure that readily leads to non-uniform expansion. Non-uniform expansion in turn creates a stent safety problem. We explain how a stent may be simplified to a serial unstable structure, and present a method to calculate the non-uniform expansion of the stent on the basis of the serial unstable structure. We propose a safety criterion based on the expansion displacement instead of the strain, and explain that the parameter Rd, the ratio of the maximum displacement of the elements to normal displacement, is meaningful to assess the safety level of the stent. We also examine how laser cutting influences non-uniform expansion. The examples illustrate how to calculate the parameter Rd to assess non-uniform expansion of the stent, and demonstrate how the laser cutting offset and strengthening coefficient of the material influence the stent expansion behaviour. The methods are valuable for assessing stent safety due to non-uniform expansion.
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Driscoll A, Davidson P, Hood S, Huang N, Aho Z, Atherton J, Stewart S, Sindone A, Krum H. Best Practice for Australian Chronic Heart Failure Management Programs. Heart Lung Circ 2009. [DOI: 10.1016/j.hlc.2009.05.386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Jing FJ, Huang N, Liu YW, Zhang W, Zhao XB, Fu RKY, Wang JB, Shao ZY, Chen JY, Leng YX, Liu XY, Chu PK. Hemocompatibility and antibacterial properties of lanthanum oxide films synthesized by dual plasma deposition. J Biomed Mater Res A 2008; 87:1027-33. [DOI: 10.1002/jbm.a.31838] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Jing FJ, Huang N, Liu YW, Zhang W, Zhao XB, Fu RKY, Wang JB, Shao ZY, Chen JY, Leng YX, Liu XY, Chu PK. Hemocompatibility and antibacterial properties of lanthanum oxide films synthesized by dual plasma deposition. J Biomed Mater Res A 2008. [PMID: 18257083 DOI: 10.1016/j.tsf.2006.07.137] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Lanthanum oxide (La(2)O(3)) films with good hemocompatibility and antibacterial properties have been fabricated using dual plasma deposition. X-ray photoelectron spectroscopy (XPS) shows that La exists in the +3 oxidation state. The band gap of the materials is determined to be 3.6 eV. Activated partial thromboplastin time (APTT) and blood platelet adhesion tests were used to evaluate the blood compatibility. The bacteria, Staphylococcus aureus, were used in plate counting tests to determine the surface antibacterial properties. The APTT is a little longer than those of blood plasma and stainless steel (SS). Furthermore, the numbers of adhered, aggregated, and morphologically changed platelets are reduced compared with those on low-temperature isotropic carbon and SS. The antibacterial plate-counting test indicates that La(2)O(3) has good antibacterial activity against S. aureus. These unique hemocompatibility and antibacterial properties make La(2)O(3) useful in many biomedical applications.
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Deng L, Pan X, Wang Y, Wang L, Zhou XE, Li M, Feng Y, Wu Q, Wang B, Huang N. Hemoglobin and its derived peptides may play a role in the antibacterial mechanism of the vagina. Hum Reprod 2008; 24:211-8. [DOI: 10.1093/humrep/den318] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Simms LA, Doecke JD, Walsh MD, Huang N, Fowler EV, Radford-Smith GL. Reduced alpha-defensin expression is associated with inflammation and not NOD2 mutation status in ileal Crohn's disease. Gut 2008; 57:903-10. [PMID: 18305068 DOI: 10.1136/gut.2007.142588] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIMS Reduced ileal Paneth cell alpha-defensin expression has been reported to be associated with Crohn's disease, especially in patients carrying NOD2 mutations. The aim of this study was to independently assess whether NOD2, alpha-defensins and Crohn's disease are linked. METHODS Using quantitative real-time polymerase chain reaction (RT-PCR), we measured the mRNA expression levels of key Paneth cell antimicrobial peptides (DEFA5, DEFA6, LYZ, PLA2G2A), inflammatory cytokines [interkelukin 6 (IL6) and IL8], and a marker of epithelial cell content, villin (VIL1) in 106 samples from both affected ileum (inflamed Crohn's disease cases, n = 44) and unaffected ileum (non-inflamed; Crohn's disease cases, n = 51 and controls, n = 11). Anti-human defensin 5 (HD-5) and haematoxylin/eosin immunohistochemical staining was performed on parallel sections from NOD2 wild-type and NOD2 mutant ileal Crohn's disease tissue. RESULTS In Crohn's disease patients, DEFA5 and DEFA6 mRNA expression levels were 1.9- and 2.2-fold lower, respectively, in histologically confirmed inflamed ileal mucosa after adjustment for confounders (DEFA5, p<0.001; DEFA6, p = 0.001). In contrast to previous studies, we found no significant association between alpha-defensin expression and NOD2 genotype. HD-5 protein data supports these RNA findings. The reduction in HD-5 protein expression appears due to surface epithelial cell loss and reduced Paneth cell numbers as a consequence of tissue damage. CONCLUSIONS Reduction in alpha-defensin expression is independent of NOD2 status and is due to loss of surface epithelium as a consequence of inflammatory changes rather than being the inciting event prior to inflammation in ileal Crohn's disease.
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Chang LC, Huang N, Chou YJ, Kao FY, Hsieh PC, Huang YT. Patterns of combined prescriptions of aspirin–Ginkgo biloba in Taiwan: a population-based study. J Clin Pharm Ther 2008; 33:243-9. [DOI: 10.1111/j.1365-2710.2008.00911.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Fall A, Huang N, Bertrand F, Ovarlez G, Bonn D. Shear thickening of cornstarch suspensions as a reentrant jamming transition. PHYSICAL REVIEW LETTERS 2008; 100:018301. [PMID: 18232829 DOI: 10.1103/physrevlett.100.018301] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Indexed: 05/25/2023]
Abstract
We study the rheology of cornstarch suspensions, a non-Brownian particle system that exhibits shear thickening. From magnetic resonance imaging velocimetry and classical rheology it follows that as a function of the applied stress the suspension is first solid (yield stress), then liquid, and then solid again when it shear thickens. For the onset of thickening we find that the smaller the gap of the shear cell, the lower the shear rate at which thickening occurs. Shear thickening can then be interpreted as the consequence of dilatancy: the system under flow wants to dilate but instead undergoes a jamming transition because it is confined, as confirmed by measurement of the dilation of the suspension as a function of the shear rate.
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Pan CJ, Shao ZY, Tang JJ, Wang J, Huang N. In vitro studies of platelet adhesion, activation, and protein adsorption on curcumin-eluting biodegradable stent materials. J Biomed Mater Res A 2007; 82:740-6. [PMID: 17326229 DOI: 10.1002/jbm.a.31108] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A major complication of coronary stenting is in-stent restenosis (ISR) due to thrombus formation. We hypothesized that locally released curcumin from coronary stent surface would inhibit ISR due to thrombus formation because of antithrombosis of curcumin. In the present work, curcumin-eluting polylactic acid-co-glycolic acid (PLGA) films were fabricated and their properties in vitro were investigated. The in vitro platelet adhesion and activation, as well as protein adsorption on curcumin-loading PLGA films were investigated to evaluate the blood compatibility of curcumin-eluting films. The structure of curcumin-eluting PLGA film and control was examined by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicating that the peaks of curcumin did not shift in curcumin-eluting films. The results of contact angle and surface free energy indicated that loading curcumin in PLGA would make PLGA become more hydrophilic, which contributed to the increase of polar fraction of surface free energy. With the increase of curcumin in films, platelets adhering to the curcumin-eluting films decreased significantly. The number of activation platelets decreased after incorporating curcumin in PLGA films. Loading curcumin in PLGA film can markedly reduce the fibrinogen adsorption. All results indicated that incorporating curcumin in PLGA film can improve the blood compatibility of PLGA films. It can be used to fabricate drug-eluting stent to prevent thrombosis formation.
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Pan CJ, Tang JJ, Weng YJ, Wang J, Huang N. Preparation and characterization of rapamycin-loaded PLGA coating stent. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2007; 18:2193-8. [PMID: 17607513 DOI: 10.1007/s10856-007-3075-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2006] [Accepted: 04/02/2007] [Indexed: 05/16/2023]
Abstract
In this study, using polylactic acid-co-glycolic acid (PLGA) with a molecular weight of 95,800 Da as drug carrier, three dose (low, moderate, high) rapamycin-eluting stents and the corresponding coating films were prepared. The pre- and post-expansion morphology of the rapamycin-eluting stent was examined by scanning electron microscopy (SEM), indicating that the coating was very smooth and uniform. The coating had the ability to withstand the compressive and tensile strains imparted without cracking from the stent during expansion process. There were many voids on stent coating surface after released for 18 days in release medium. The thermodynamics data of the stent coating film measured by differential scanning calorimetry (DSC) showed a lack of measurable solubility of rapamycin in the PLGA matrix. The release behavior of rapamycin from stent surface had a two phase release profile with a burst release period of about 2 days, followed by a sustained and slow release phase. The mass loss behavior of PLGA appeared linear throughout most of the degradation period, corresponding to an approximately constant mass loss rate. The platelet adhesion tests showed that the rapamycin-eluting films may have a good blood compatibility compared with control samples. Take into these results account, this novel rapamycin-eluting may be a good candidate to resolve in-stent restenosis.
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Wan G, Huang N, Yang P, Fu RK, Ho JP, Xie X, Zhou H, Chu PK. Platelet activation behavior on nitrogen plasma-implanted silicon. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2007. [DOI: 10.1016/j.msec.2006.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/01/2022]
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Pan CJ, Tang JJ, Shao ZY, Wang J, Huang N. Improved blood compatibility of rapamycin-eluting stent by incorporating curcumin. Colloids Surf B Biointerfaces 2007; 59:105-11. [PMID: 17540543 DOI: 10.1016/j.colsurfb.2007.04.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 04/10/2007] [Accepted: 04/25/2007] [Indexed: 11/17/2022]
Abstract
This paper dealt with improving the blood compatibility of the rapamycin-eluting stent by incorporating curcumin. The rapamycin- and rapamycin/curcumin-loaded PLGA (poly(d,l-lactic acid-co-glycolic acid)) coatings were fabricated onto the surface of the stainless steel stents using an ultrasonic atomization spray method. The structure of the coating films was characterized by Fourier transform infrared spectroscopy (FTIR). The optical microscopy and scanning electron microscopy (SEM) images of the drug-eluting stents indicated that the surface of all drug-eluting stents was very smooth and uniform, and there were not webbings and "bridges" between struts. There were not any cracks and delaminations on stent surface after expanded by the angioplasty balloon. The in vitro platelet adhesion and activation were investigated by static platelet adhesion test and GMP140 (P-selection), respectively. The clotting time was examined by activated partially prothromplastin time (APTT) test. The fibrinogen adsorption on the drug-loaded PLGA films was evaluated by enzyme-linked immunosorbent assay (ELISA). All obtained data showed that incorporating curcumin in rapamycin-loaded PLGA coating can significantly decrease platelet adhesion and activation, prolong APTT clotting time as well as decrease the fibrinogen adsorption. All results indicated that incorporating curcumin in rapamycin-eluting coating obviously improve the blood compatibility of rapamycin-eluting stents. It was suggested that it may be possible to develop a drug-eluting stent which had the characteristics of not only good anti-proliferation but also improved anticoagulation.
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Huang N, Tonkin A, Phillips S, Mackson J, Weekes L, Azam R, Slaytor E, Boyden A, Buchan H. Educational Interventions to Improve Prescribing and Use of Echocardiography in Chronic Heart Failure in Primary Care. Heart Lung Circ 2007. [DOI: 10.1016/j.hlc.2007.06.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ku B, Levinson M, Barnhart K, Hummel A, Huang N, Dean A. Presence of a Double Decidual Sign Effectively Rules-out the Possibility of Ectopic Pregnancy. Acad Emerg Med 2006. [DOI: 10.1197/j.aem.2006.09.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Huang N, Yip W, Chang HJ, Chou YJ. Trends in rural and urban differentials in incidence rates for ruptured appendicitis under the National Health Insurance in Taiwan. Public Health 2006; 120:1055-63. [PMID: 17011602 DOI: 10.1016/j.puhe.2006.06.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 04/03/2006] [Accepted: 06/20/2006] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Rural-urban disparities in health remain a major focus of concern. This population-based study examined the performance of Taiwan's universal healthcare system in reducing rural-urban disparities in health, through better accessibility. Changes in the rates of ruptured appendicitis were compared between residents of remote and non-remote areas in Taiwan, under the National Health Insurance (NHI) programme. METHODS We identified all 128,930 patients undergoing appendectomy in Taiwan between 1996 and 2001. The NHI inpatient files, enrolment files, major disease files, hospital registry and the household registry were linked to provide comprehensive individual and hospital information. Probit regression analyses were used to obtain adjusted estimates. RESULTS During the first 3 years, although the differences between the remote and non-remote areas were apparent, they were seen to be narrowing. This downward trend continued, and, since 1999, few discernible differences have been observed. After adjusting for individual and hospital characteristics, over time, the ruptured appendix rate among remote area residents was seen to be decreasing significantly faster (1.1%) than among non-remote area residents. More specifically, the children showed a substantially steeper narrowing trend (3.3%) in rural-urban disparities, than did adults. CONCLUSIONS Our findings have shown a significant narrowing of health disparities between remote and non-remote populations, resulting from free access to care and more healthcare provision in remote areas under the NHI programme; particular success has been observed in rural children. Although certain disparities still exist, Taiwan's universal healthcare system has effectively reduced rural-urban disparities in access to care and in ultimate health outcomes.
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Pan CJ, Tang JJ, Weng YJ, Wang J, Huang N. Preparation, characterization and anticoagulation of curcumin-eluting controlled biodegradable coating stents. J Control Release 2006; 116:42-9. [PMID: 17046093 DOI: 10.1016/j.jconrel.2006.08.023] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 08/10/2006] [Accepted: 08/29/2006] [Indexed: 11/24/2022]
Abstract
Curcumin is pharmaceutically active in many ways, having properties including anticoagulation, anti-proliferation, anti-inflammatory, and may be used to fabricate drug-eluting stents to treat in-stent restenosis after stent implantation. Here we describe our investigations of curcumin-eluting PLGA coatings formed using the biodegradable polymer PLGA (polylactic acid-co-glycolic acid) as drug carrier and uniformly fabricated on the surface of 316L stainless steel stents by an ultrasonic spray method. Three doses were explored--low dose ( approximately 140 microg per stent or 115 microg/cm(2)), moderate dose ( approximately 280 microg per stent or 230 microg/cm(2)), and high dose ( approximately 490 microg per stent or 408 microg/cm(2)). Pre- and post-expansion morphologies of the stent coating were examined by optical microscopy (OM) and scanning electron microscopy (SEM), indicating that the coating not only was very smooth and uniform but also had the ability to withstand the compressive and tensile strains imparted without cracking from the stent during the expansion process. Atomic force microscopy (AFM) images indicated the topography of the PLGA-only and moderate dose curcumin-eluting stent that showed an average roughness below 1 nm; no drug particles could be seen on the stent surface, indicating that curcumin can be mixed with PLGA at the molecular level using an ultrasonic atomization spray method. The structure of the coating films was characterized by Fourier Transform Infrared (FTIR) spectroscopy and X-ray electron spectroscopy (XPS), with results suggesting that there was no chemical reaction between curcumin and the drug. The results of in vitro measurements of drug release from curcumin-eluting stents showed that all the curcumin-eluting stents studied exhibited a nearly linear sustained-release profile with no significant burst releases within the measurement period. The in vitro anticoagulation behavior of curcumin-eluting stents was investigated by static platelet adhesion and APTT (activated partial thromboplastin time) tests, revealing that the anticoagulation properties of curcumin-eluting stents are superior to those for stainless steel stents and PLGA-only-coated stents. The anticoagulation behavior of curcumin stents improved significantly as the drug dose was increased.
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Deng CY, Huang N, Chou YJ, Hsu YJ, Chen LS, Chou P. Comparison of perforation risk among physicians, other medical professionals and general adults with acute appendicitis in Taiwan. Br J Surg 2006; 93:1297-302. [PMID: 16862611 DOI: 10.1002/bjs.5435] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Abstract
Background
This study aimed to compare the risk of appendiceal perforation among physicians, other medical professionals and general adults, when hospitalized for acute appendicitis.
Methods
National population-based data for 92 143 patients with acute appendicitis, aged 20 years or more, who underwent appendicectomy or drainage of an appendiceal abscess in Taiwan from 1996 to 2001 were analysed retrospectively. The outcome measure was appendiceal perforation. Patients were categorized as physicians (Western medical doctors), other medical professionals (such as dentists or nurses) or general adults (not medical professionals). Adjusted odds ratios and 95 per cent confidence intervals (c.i.) were estimated by multiple logistic regression.
Results
Multivariable analysis showed that appendiceal perforation was 0·67 (95 per cent c.i. 0·46 to 0·96) and 0·78 (95 per cent c.i. 0·62 to 0·99) times less likely in physicians and other medical professionals respectively than in general adults, after adjusting for patient and admitting hospital characteristics, and for calendar year.
Conclusion
The risk of perforation was significantly lower among physicians and other medical professionals than in general adults. Medical knowledge, familiarity with the healthcare system and better patient–doctor communication may have been contributory factors.
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Zheng XJ, Huang N, Zhou Y. The effect of electrostatic force on the evolution of sand saltation cloud. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 19:129-38. [PMID: 16491314 DOI: 10.1140/epje/e2006-00020-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Indexed: 05/06/2023]
Abstract
In a wind-blown sand layer, it has been found that wind transport of particles is always associated with separation of electric charge. This electrification in turn produces some electrostatic forces in addition to the gravitational and fluid friction forces that affect the movement of saltating sand particles, further, the wind-blown sand saltation. To evaluate this effect quantitatively, this paper presents a simulation of evolution of wind-blown sand grains after the electrostatic forces exerted on the grains are taken into account in the wind feedback mechanism of wind-blown saltation. That is, the coupling interaction between the wind flow and the saltating sand particles is employed in the simulation to the non-stationary wind and sand flows when considering fluid drag, gravitation, and a kind of electrostatic force generated from a distribution of electric field changing with time in the evolution process of the sand saltation. On the basis of the proposed simulation model, a numerical program is given to perform the simulation of this dynamic process and some characteristic quantities, e.g., duration of the system to reach the steady state, and curves of the saltating grain number, grain transport rate, mass-flux profile, and wind profile varying with time during the non-stationary evolution are displayed. The obtained numerical results exhibit that the electrostatic force is closely related to the average charge-to-mass ratio of sand particles and has obvious influence on these characteristic quantities. The obtained results also show that the duration of the system to reach the steady state, the sand transport rate and the mass flux profile coincide well with experimental results by Shao and Raupach (1992) when the average charge-to-mass ratio of sand particles is 60 microC/kg for the sand particles with average diameter of 0.25 mm. When the average charge-to-mass ratios of sand particles are taken as some other certain values, the calculation results still show that the mass flux profiles are well in agreement with the experimental data by Rasmussen and Mikkelsen (1998) for another category of sand particles, which tell us that the electrostatic force is one of main factors that have to be considered in the research of mechanism of wind-blown sand saltation.
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Singleton K, Huang N, Booth A, Lombard C, Nowson C. 36 Active Nutrition Script: a double-edged sword for lifestyle prescription in general practice. J Sci Med Sport 2005. [DOI: 10.1016/s1440-2440(17)30531-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Smith B, Marshall A, Huang N. 214 Assessing physical activity in general practice: Evaluating the feasibility, reliability and validity of two short instruments. J Sci Med Sport 2005. [DOI: 10.1016/s1440-2440(17)30710-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sims J, Gunn J, Hill K, Huang N, Davidson S. 203 The UPLIFT study: using progressive resistance training to promote the mental health of older people in the primary care setting. J Sci Med Sport 2005. [DOI: 10.1016/s1440-2440(17)30699-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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