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efficient Variable-Coefficient Finite-Volume Stokes Solvers

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Communications in Computational Physics 2014年第10期16卷 1263-1297页

作者： Mingchao Cai Andy Nonaka John B.Bell Boyce e.Griffith Aleksandar Donev Courant Institute of Mathematical Sciences New York UniversityNew YorkNY 10012USA. Center for Computational Sciences and engineering Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA. Leon H.Charney Division of Cardiology Department of MedicineNew York University School of MedicineNYUSA. Department of Mathematics University of North CarolinaChapel HillNC 27599USA

We investigate several robust preconditioners for solving the saddle-point linear systems that arise from spatial discretization of unsteady and steady variablecoefficient Stokes equations on a uniform staggered *** on the success of using the classical projection method as a preconditioner for the coupled velocitypressure system[***,***.,228(2009),pp.7565–7595],as well as established techniques for steady and unsteady Stokes flow in the finite-element literature,we construct preconditioners that employ independent generalized Helmholtz and Poisson solvers for the velocity and pressure *** demonstrate that only a single cycle of a standard geometric multigrid algorithm serves as an effective inexact solver for each of these *** to traditional wisdom,we find that the Stokes problem can be solved nearly as efficiently as the independent pressure and velocity subproblems,making the overall cost of solving the Stokes system comparable to the cost of classical projection or fractional step methods for incompressible flow,even for steady flow and in the presence of large density and viscosity *** of the five preconditioners considered here are found to be robust to GMReS restarts and to increasing problem size,making them suitable for large-scale *** work opens many possibilities for constructing novel unsplit temporal integrators for finite-volume spatial discretizations of the equations of low Mach and incompressible flow dynamics.

关键词： Stokes flow variable density variable viscosity saddle point problems projection method preconditioning GMReS.

Global properties of a cell mediated immunity in HIV infection model with two classes of target cells and distributed delays

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International Journal of Biomathematics 2014年第5期7卷 119-143页

作者： A. M. elaiw R. M. Abukwaik e. O. Alzahrani Department of Mathematics Faculty of Science King Abdulaziz University P. O. Box 80203 Jeddah 21589 Saudi Arabia Department of Mathematics Faculty of Science AI-Azhar University Assiut Egypt

In this paper, we study the global properties of a human immunodeficiency virus （HIV） infection model with cytotoxic T lymphocytes （CTL） immune response. The model is a six-dimensional that describes the interaction of the HIV with two classes of target cells, CD4＋ T cells and macrophages. The infection rate is given by saturation functional response. Two types of distributed time delays are incorporated into the model to describe the time needed for infection of target cell and virus replication. Using the method of Lyapunov functional, we have established that the global stability of the model is determined by two threshold numbers, the basic infection reproduction number R0 and the immune response activation number R0. We have proven that if R0 ≤ 1, then the uninfected steady state is globally asymptotically stable （GAS）, if R0≤ 1 〈 R0, then the infected steady state without CTL immune response is GAS, and if R0〉 1, then the infected steady state with CTL immune response is GAS.

关键词： Global stability HIV dynamics delay cell mediated immunity.

ON THe PHYSICS OF FLOW-DRIVeN SeDIMeNTS (BeD-LOAD)

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International Journal of Sediment Research 2001年第1期16卷 1-18页

作者： Ulrich C. e. ZANKe Prof, Institute of Hydraulic engineering, University of Technology, Darmstadt, Germany Institute of Hydraulic engineering University of Technology Darmstadt Germany

More than three dozen significant formulae for bed-load transport have been developed over a period of more than 100 years with varying degrees of success. Major problems have been the use of completely or partly empirical approaches and too few data for fitting. This paper presents an analytical formulation for bed-load transport. It is based on a balance of forces for the determination of the thickness of the moving bed-load layer and on the determination of the velocity of this layer. The formula derived is compared to a set of approx. 2000 data published by 32 authors. It is demonstrated that the basic form of the MPM-formula is a special case of the analytical solution. The derivation also includes the effect of bed features such as ripples and dunes on quantitative transport.

关键词： Bed-load transport Meyer-Peter/Mueller formula Moving bed-load layer Threshold concept Suspended load

Preventive effects of cannabis on neurotoxic and hepatotoxic activities of malathion in rat

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Asian Pacific Journal of Tropical Medicine 2018年第4期11卷 272-279页

作者： Omar M.e.Abdel-Salam Amany A Sleem eman R Youness Fatma A.Morsy Department of Toxicology and Narcotics National Research Centre Department of Pharmacology National Research Centre Department of Medical Biochemistry National Research Centre Department of Pathology National Research Centre

Objective: To investigate the effect of Cannabis sativa extract on the development of neuroand hepato-toxicity caused by malathion injection in rats. Methods: The extract of Cannabis sativa was obtained from the plant resin by chloroform treatment. Δ~9-Tetrahydrocannabinol content of the extract(20%) was quantified using gas chromatography–mass spectrometry. The doses of cannabis extract were expressed as Δ~9-tetrahydrocannabinol content of 10 or 20 mg/kg. Malathion(150 mg/kg) was intraperitoneally administered followed after 30 min by the cannabis extract(10 or 20 mg/kg, subcutaneously). Rats were euthanized 4 h later. Malondialdehyde(MDA), reduced glutathione(GSH), nitric oxide and paraoxonase-1(PON-1) activity were determined in brain and liver. Brain 5-lipoxygenase and butyrylcholinesterase(BChe) activity were measured as well. Histopathological examination of brain and liver tissue was also performed. Results: Compared to controls, malathion resulted in increased oxidative stress in brain and liver. MDA and nitric oxide concentrations were significantly increased(Pecreased with respect to control levels(Ped PON-1 and BChe activities but had no effect on brain 5-lipoxygenase. Brain MDA concentrations were not altered by cannabis treatment. Cannabis at 20 mg/kg, however, caused significant increase in nitric oxide and restored the GSH and PON-1 activity. Brain BChe activity significantly decreased by 26.1%(Per treatment with 10 mg/kg cannabis. Cannabis showed no effect on brain 5-lipoxygenase. On the other hand, rats treated with cannabis exhibited significantly higher levels of liver MDA, nitric oxide and PON-1 activity compared with the malathion control group. Rats treated with only malathion exhibited spongiform changes, neuronal damage in the cerebral cortex and degeneration of some Purkinje cells in the cerebellum. There were also hepatic vacuolar degeneration and dilated an

关键词： Cannabis sativa Malathion Liver damage Brain damage Oxidative stress Paraoxonase 5-Lipoxygenase

Mesenchymal stem cells as living anti-inflammatory therapy for COVID-19 related acute respiratory distress syndrome

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World Journal of Stem Cells 2020年第10期12卷 1067-1079页

作者： Feng Lin Thomas e Ichim Sandeep Pingle Lawrence D Jones Santosh Kesari Shashaanka Ashili Research and Development CureScienceSan DiegoCA 92121United States Cancer Center John Wayne Cancer Institute and Pacific Neuroscience Institute at Providence Saint John's Health CenterSanta MonicaCA 90404United States

Coronavirus disease 2019(COVID-19),a pandemic disease caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV2),is growing at an exponential rate *** of this disease are heterogeneous;however,advanced cases often exhibit various acute respiratory distress syndrome-like symptoms,systemic inflammatory reactions,coagulopathy,and organ involvements.A common theme in advanced COVID-19 is unrestrained immune activation,classically referred to as a“cytokine storm”,as well as deficiencies in immune regulatory mechanisms such as T regulatory *** mesenchymal stem cells(MSCs)themselves are objects of cytokine regulation,they can secrete cytokines to modulate immune cells by inducing antiinflammatory regulatory Treg cells,macrophages and neutrophils;and by reducing the activation of T and B cells,dendritic and nature killer ***,they have therapeutic potential for treating severe cases of *** we discuss the unique ability of MSCs,to act as a“living antiinflammatory”,which can“rebalance”the cytokine/immune responses to restore *** also discuss current MSC trials and present different concepts for optimization of MSC therapy in patients with COVID-19 acute respiratory distress syndrome.

关键词： Mesenchymal stem cells SARS-CoV-2 COVID-19 Cytokine storm Acute respiratory distress syndrome Immunomodulation

Ischemic colitis:Clinical practice in diagnosis and treatment

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World Journal of Gastroenterology 2008年第48期14卷 7302-7308页

作者： Angeliki Theodoropoulou Ioannis e Koutroubakis Gastroenterology Unit Veni- zelion General Hospital of Heraklion Department of Gastroenterology University Hospital Heraklion

Ischemic colitis is the most common form of ischemic injury of the gastrointestinal tract and can present either as an occlusive or a non-occlusive form. It accounts for 1 in 1000 hospitalizations but its incidence is underesti- mated because it often has a mild and transient nature. The etiology of ischemic colitis is multifactorial and the clinical presentation variable. The diagnosis is based on a combination of clinical suspicion, radiographic, endo- scopic and histological findings. Therapy and outcome depends on the severity of the disease. Most cases of the non-gangrenous form are transient and resolve spontaneously without complications. On the other hand, high morbidity and mortality and urgent operative intervention are the hallmarks of gangrenous ischemic colitis.

关键词： Colon ischemia Intestinal blood flow Isch-emic colitis Thrombosis

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铸造混合型旧砂的复合再生工艺研究

铸造 2024年第6期73卷 799-803页

作者：韩海涛韩继磊王大威刘宁李宝娥师春生李海鹏承德北雁新材料科技有限公司河北承德068451 河北省硅砂材料技术创新中心河北承德068451 河北工业大学材料科学与工程学院天津300130 天津大学材料科学与工程学院天津300350

对含不同类型树脂芯砂的粘土混合旧砂进行再生试验研究,对比了湿法再生、化学再生和复合再生等对再生砂表面形貌和性能的影响。结果表明:单一再生方法无法同时满足对含泥量、灼减量、酸耗值等要求。“水洗+碱/酸处理+高温焙烧”工艺能... 详细信息

对含不同类型树脂芯砂的粘土混合旧砂进行再生试验研究,对比了湿法再生、化学再生和复合再生等对再生砂表面形貌和性能的影响。结果表明:单一再生方法无法同时满足对含泥量、灼减量、酸耗值等要求。“水洗+碱/酸处理+高温焙烧”工艺能充分发挥不同工艺优势,获得理想结果,适宜的工艺参数为在400 r/min的转速下水洗6次,每次5 min,砂水比约为1.7∶1,并在水洗初期和水洗后每100 g旧砂依次加入0.1 mol/L的氢氧化钠溶液4 mL和草酸溶液6 mL,最后将水洗后的砂子在700℃焙烧15 min。再生砂含泥量、酸耗值、灼减量分别达到0.18%,2.61 mL和0.08%,均超过行业标准和企业生产要求。

关键词：粘土混合旧砂复合再生微观形貌工艺性能

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Use of ultrasound to modify the pyrolyzed biomass of Pinus *** the implications for biological models

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Information Processing in Agriculture 2018年第2期5卷 199-204页

作者： Aislan R.Guimaraes Marcelo e.Cordeiro Jaqueline Nicolini Keller P.Nicolini Chemistry Department Federal Institute of ParanaCampus PalmasPR CEP 85555-000Brazil

Pine(Pinus ssp.)needle biomass(PNB)was pyrolyzed at 400℃ for 3 h and then subjected to hydrothermal treatment at the same temperature for 10 min,with and without the addition of potassium chloride(KCl).The suspensions of the materials treated hydrothermally were submitted to ultrasound for 5,10,20,30 and 60 *** reflectance UV-Vis(DRUV)spectroscopy results for the materials with variations in sonication times were obtained and the band gap energy(e)was calculated.A culture medium containing Saccharomyces cerevisiae was monitored during 30 min of exposure to different materials for the calculation of the 10%(IC10),30%(IC30)and 50%(IC50)inhibitory *** the samples that underwent ultrasonic treatment,the material pyrolyzed at 400℃ without the addition of potassium ions(PNB4003H60)presented the greatest inhibition of 10% of the Saccharomyces cerevisiae *** the materials without the addition of potassium,the material pyrolyzed and sonicated for 10 min(PNB4003H10)showed the best characteristics for use as a support for Saccharomyces cerevisiae organisms.

关键词： Potassium Saccharomyces cerevisiae Spectroscopy

Deposition behavior and tribological properties of diamond-like carbon coatings on stainless steels via chemical vapor deposition

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International Journal of Minerals,Metallurgy and Materials 2018年第11期25卷 1335-1343页

作者： Labani Mustafi M.M.Rahman Mohammad Nur e Alam Al Nasim Mohammad Asaduzzaman Chowdhury M.H.Monir School of Materials Science and engineering Harbin Institute of TechnologyHarbin 150001China School of engineering RMIT UniversityMelbourneVictoria 3001Australia Dhaka University of engineering and Technology Gazipur 1707Bangladesh

A systematic investigation was carried out to observe the deposition rate of a diamond-like carbon(DLC) coating on two stainless steel substrates by chemical vapor deposition(CVD). The objective of this research is to study the deposition behavior of the DLC coating and its tribological properties in different combinations of methane(CH_4) and nitrogen, which were used as precursor gases. The results reveal that the deposition rate increases with increasing CH_4 content up to 50 vol%. The hardness of the DLC-deposited layer also increases while the friction coefficient decreases with increasing CH_4 gas content up to 50% in the precursor gas mixture.

关键词： diamond-like carbon chemical vapor deposition methane and nitrogen gas mixtures deposition rate hardness friction coefficient

维普期刊数据库