检索结果-南通市图书馆

Mathematical modeling and optimal intervention of COVID-19 outbreak

在线全文

学校读者我要写书评

暂无评论

Quantitative Biology 2021年第1期9卷 84-92页

作者： Saroj k Biswas Nasir U ahmed Department of Electrical and Computer Engineering Temple UniversityPhiladelphiaPA19122USA School of Electrical Engineering and Computer Science University of OttawaOttawaK1N 6N5Canada

Background:The COVID-19 pandemic has become a formidable threat to global health and *** coronavirus SARS-CoV-2 that causes COVID-19 is known to spread by human-to-human transmission,and in about 40%cases,the exposed individuals are asymptomatic which makes it difficult to contain the ***:This paper presents a modified SEIR epidemiological model and uses concepts of optimal control theory for analysis of the effects of intervention methods of the *** the pandemic intervention problem can be viewed as a mathematical optimization problem as there are contradictory outcomes in terms of reduced infection and fatalities but with serious economic ***:Concepts of optimal control theory have been used to determine the optimal control(intervention)levels of i)social contact mitigation and suppression,and ii)pharmaceutical intervention modalities,with minimum impacts on the *** results show that with optimal intervention policies,there is a significant reduction in the number of infections and *** computed optimum intervention policy also provides a timeline of systematic enforcement and relaxation of stay-at-home regulations,and an estimate of the peak time and number of hospitalized critical care ***:The proposed method could be used by local and state governments in planning effective strategies in combating the *** optimum intervention policy provides the necessary lead time to establish necessary field hospitals before getting overwhelmed by new patient *** results also allow the local and state governments to relax social contact suppression guidelines in an orderly manner without triggering a second wave.

关键词： coronavirus COVID-19 SEIR model epidemic model optimization

Numerical investigation on the heat transfer enhancement using a confined slot impinging jet with nanofluid

在线全文

学校读者我要写书评

暂无评论

Propulsion and Power Research 2019年第4期8卷 351-361页

作者： Ibrahim k.Alabdaly M.A.ahmed Department of Mechanical Engineering College of EngineeringUniversity of AnbarRamadiAnbarIraq

In this article,laminar convective heat transfer of a confined slot impinging jet with nanofluid has been numerically investigated over Reynolds number ranges of *** circular ribs are mounted on the lower-target surface:one rib located right the stagnation point and another one located on the left of the stagnation ***2-water nanofluid with nanoparticles volume fraction ranging from 0 to 4%and nanoparticles diameters of 30 nm has been *** two-dimensional governing continuity,momentum and energy equations have been solved using finite volume method based on SIMPLE *** effect of Reynolds number,nanoparticles volume fraction,rib height and rib location on the flow and thermal characteristics are presented and *** showed that the average Nusselt number,performance factor,total entropy generation as well as friction factor increase with increasing nanoparticles volume *** addition,it is found that the best thermal-hydraulic performance factor is around 1.89 which is obtained at Reynolds number of 1000,nanoparticles volume fraction of 4%,the rib height of 0.1 and the rib location of 2.

关键词： Jet impingement Nanofluid Entropy generation Thermal-hydraulic performance Finite volume method

Antioxidant Machinery Related to Decreased MDA Generation by Thymus Algeriensis Essential Oil-induced Liver and kidney Regeneration

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2016年第9期29卷 639-649页

作者： Guesmi Fatma Amit k Tyagi Bellamine Houda Landoulsi ahmed Laboratory of Biochemistry and Molecular Biology Faculty of Sciences of Bizerte University of Carthage 1054 Tunisia Department of Experimental Therapeutics The University of Texas M. D. Anderson Cancer Center 1515 Holcombe Boulevard Houston TX 77030 USA Service of Anatomo-Pathology of Menzel Bourguiba Bizerte 1054 Tunisia

Objective This study was conducted to determine the histopathological and biochemical effects of Thymus algeriensis essential oil （TEO） on hydrogen peroxide （H2O2）-induced oxidative stress in liver and kidney tissues of rats. Methods Rats were treated in six groups and were exposed for 2 weeks to low （LD; 100 μmol/L） and high doses （HD; 1 mmol/L） of H2O2 in the presence or absence of TEO （180 mg/kg）. Liver and kidney atrophy was measured by using biochemical and histopathological assays. Results Our study demonstrated that H2O2 induced liver and kidney atrophy, as evidenced by the significant elevation of serum aminotransferase, urea, and creatinine levels compared with those in the control rats. Urea levels were estimated by evaluating the activity of serum urease that hydrolyzes urea into CO2 and ammonia. However, TEO treatment significantly alleviated oxidative stress in the H2O2-induced liver and kidney toxicity model by reducing the levels of malondialdehyde concomitantly with marked elevations in superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase, as well as decrease in glutathione activity. Conclusion Our data demonstrated that TEO protected against H202 toxicity by decreasing oxidant levels and DNA damage, as well as increasing antioxidant levels, indicating that TEO has a spectrum of antioxidant and DNA-protective properties.

关键词： Liver and kidney atrophy Hydrogen peroxide Thymus algeriensis Antioxidants Toxicity

Preparation and Reactions of 2-Methyl-7-（3-methyl-5-oxo-1- phenyl-2-pyrazolin-4-yl）-5-arylthiazolo[3,2-a]- pyrimido[4,5-d]oxazin-4（5H）-one

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2011年第7期29卷 1473-1482页

作者： Youssef, Mohamed Salah k. Abbady, Mohamed S. ahmed, Ragaa A. Omar, ahmed A. Chemistry Department Faculty of Science Assiut University Assiut 71516 Egypt

Ethyl 7-amino-3-（3-methyl-5-oxo- 1-phenyl-2-pyrazolin-4-yl）-5-aryl-5H-thiazolo[3,2-a]pyrimidine-6-carboxy- late was hydrolyzed with an ethanolic sodium hydroxide and the sodium salt thus formed underwent cyclization with acetic anhydride to afford 2-methyl-7-（3-methyl-5-oxo-l-phenyl-2-pyrazolin-4-yl）-5-arylthiazolo[3,2-a]- pyrimido[4,5-d]oxazin-4（SH）-one. This compound was transformed to related heterocyclic systems via its reaction with various reagents. The biological activity of the prepared compounds was tested against Gram positive and Gram negative bacteria as well as yeast-like and filamentous fungi. They revealed in some cases excellent biocidal properties.

关键词： thiazolopyrimidooxazinone thiazolopyrimidopyrimidines antimicrobial activity

Effect of Pd or Ir on the catalytic performance of Mo/H-ZSM-5 during the non-oxidative conversion of natural gas to petrochemicals

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2008年第4期17卷 337-343页

作者： ahmed k.Aboul-Gheit ahmed E.Awadallah Salah M.El-kossy Abdel-Lateef H.Mahmoud Process Development Division Egyptian Petroleum Research Institute Faculty of Science Department of ChemistryMNF University Ageeba Petroleum Co.

Natural gas conversion to petrochemicals, principally, benzene, naphthalene, toluene, as well as ethylene under non-oxidative conditions was examined in a fixed bed flow reactor at 700 ℃ and gaseous hourly space velocity （GHSV） of 1500 ml·g ^-1·h^-1 at time-on-stream ranging from 5 rain to 4 h using catalysts containing 6.0%Mo/H-ZSM-5 promoted with Pd or Ir metal. The catalysts were characterized by XRD, TPD, and TGA. The addition of Pd or Ir to 6%Mo/H-ZSM-5 catalyst promoted ethylene production but inhibited the cyclization reaction to aromatics owing to the strong interaction between these noble metals and the framework Al species, which were attached to the acid sites during the impregnation process. Coke deposition on the catalysts was found to decrease upon addition of 0.5wt% of Pd or Ir to 6%Mo/H-ZSM-5 catalyst owing to the hydrogenating activity of these metals.

关键词： natural gas methane benzene ethylene molybdenum Pd Ir H-ZSM-5

Microstructural features of flower like Fe brushite

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2017年第4期27卷 520-526页

作者： S.I.El-dek S.F.Mansour M.A.ahmed M.k.ahmed Materials Science and Nanotechnology Department Faculty of Post Graduate Studies for Advanced Science Beni-Suef University Physics Department Faculty of ScienceZagazig University Materials Science Lab(1) Physics Department Faculty of Science Cairo University

The iron doped brushite(Fe-DCPD) nano particles were synthesized via co-precipitation method with Fe concentrations(0 ≤x≤ 1) in steps 0.2. The influence of iron concentration on the crystallinity, particle shape,morphology, optical, magnetic and electrical properties was investigated. The results showed that iron doping content is the crucial factor in the variation of physical properties. The particle shape changed from spheres at x=0.2 to be fiber network at x = 0.8. The saturation magnetization(Ms) increased from 0.4(emu/g) at x = 0.2 to 1.6(emu/g) at x = 0.8 which is considered more than four times with a considerable decrease of coercive field.

关键词： Bioceramic Calcium phosphate Brushite Fe brushite Magnetic hydroxyapatite

Corrosion behavior of cold-rolled and post heat-treated 316L stainless steel in 0.9wt%NaCl solution

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2021年第3期28卷 440-449页

作者： k.Bin Tayyab A.Farooq A.ahmed Alvi A.Basit Nadeem k.M.Deen Corrosion Control Research Cell Department of Metallurgy and Materials EngineeringUniversity of the PunjabLahorePakistan Department of Materials Engineering The University of British ColumbiaVancouverV6T 1Z4BCCanada

The effect of cold rolling and post-rolling heat treatment on the microstructural and electrochemical properties of the 316L stainless steel was ***-pass and four-pass cold-rolled stainless steel specimens were heat-treated by annealing at 900℃followed by quenching in *** the cold rolling,the microstructure of the as-received specimen transformed from austenite to strain-inducedα′-martensite due to significant plastic deformation that also resulted in significant grain elongation(i.e.,~33%and 223%increases in the grain elongation after two and four rolling passes,respectively).The hardness of the heat-treated as-received specimen decreased from HV 190 to 146 due to the recovery and recrystallization of the austenite grain *** cyclic polarization scans of the as-rolled and heat-treated specimens were obtained in 0.9wt%NaCl *** pitting potential of the four-pass rolled specimen was significantly increased from 322.3 to 930.5 mV after post-rolling heat *** beneficial effect of the heat treatment process was evident from~10-times-lower corrosion current density and two-orders-of-magnitude-lower passive current density of the heat-treated specimens compared with those of the as-rolled ***,appreciably lower corrosion rate(3.302×10^(−4)mm/a)and higher pitting resistance(1115.5 mV)were exhibited by the postrolled heat-treated specimens compared with the as-rolled 316L stainless steel specimens.

关键词： cold rolling quenching cyclic polarization re-passivation tendency

Walking experience:Exploring the trilateral interrelation of walkability,temporal perception,and urban ambiance

在线全文

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2021年第3期10卷 516-539页

作者： Doaa k.Hassan ahmed Elkhateeb Department of Architecture Faculty of EngineeringAin Shams UniversityCairoEgypt

Walking experience through urban spaces is a frequent daily ***,planning and designing for walkability become crucial for building up quality of *** daily walks around the city are affected by fulfilling the needed psychological contentment that is in turn measured unconsciously by our temporal *** contentment is inherent in what we experience in accordance with urban ambiance that goes beyond the spatial attributes of spaces to include their social and sensorial ***,the question here is how walkability of urban routes is affected by urban ambiance and therefore perceived in terms of ***,this study aims to understate the trilateral interrelation of walkability,temporal perception,and urban ambiance in walkable routes for daily routine *** work depends on an experimental study where participants are asked to walk along two selected ***-gathering tools rely on documenting the lived experience of the target group via reporting their trips and answering a *** analysis demonstrates this trilateral interrelation to clarify the *** study concludes specific qualities of walkable routes for routine use that reduce sense of time,which is highly crucial to be realized in such daily walk journeys.

关键词： Walkability Urban ambiance Temporal perception People’s needs in open spaces

Pyogenic liver abscess caused by Fusobacterium in a 21-year-old immunocompetent male

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第12期21卷 3731-3735页

作者： Zohair ahmed Saurabh k Bansal Sonu Dhillon Department of Internal Medicine University of Illinois Peoria Campus OSF Saint Francis Medical Center Department of Gastroenterology and Hepatology University of Illinois Peoria Campus OSF Saint Francis Medical Center

A 21-year-old male with no significant past medical history, presented with right upper quadrant(RUQ) abdominal pain along with fevers and chills. Lab work revealed leukocytosis, anemia, and slightly elevated alkaline phosphatase. Viral serology for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus were negative and he was *** tomography imaging revealed hepatic abscesses, the largest measuring 9.5 cm. Empiric antibiotics were started and percutaneous drains were placed in the abscesses. Anaerobic cultures from the abscesses grew Fusobacterium nucleatum. This is a gram negative anaerobic bacteria; a normal flora of the oral cavity. Fusobacterium is most commonly seen in Lemiere's disease, which is translocation of oral bacteria to the internal jugular vein causing a thrombophlebitis and subsequent spread of abscesses. Our patient did not have Lemiere's, and is the first case described of fusobacterium pyogenic liver abscess in a young immunocompetent male with good oral hygiene. This case was complicated by sepsis, empyema, and subsequent abscesses located outside the liver. These abscesses' have the propensity to flare abruptly and can be fatal. This case not only illustrates fusobacterium as a rare entity for pyogenic liver abscess, but also the need for urgent diagnosis and treatment. It is incumbent on physicians to diagnose and drain any suspicious hepatic lesions. While uncommon, such infections may develop without any overt source and can progress rapidly. Prompt drainage with antibiotic therapy remains the cornerstone of therapy.

关键词： Hepatic abscess Pyogenic Fusobacterium Liver Immun