437 research outputs found

    Protective effect of Withaferin-A on micronucleus frequency and detoxication agents during experimental oral carcinogenesis

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    Our aim was to investigate the effect of Withaferin-A on bone marrow micronucleus frequency andbuccal mucosa detoxication agents during 7, 12–dimethylbenz[a]anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Oral squamous cell carcinoma was developed in hamsters’ buccal pouches by painting 0.5% DMBA in liquid paraffin, three times per week for 14 weeks. We observed 100% tumor formation in DMBA painted hamsters. Elevated frequency of bone marrow micronucleated polychromatic erythrocytes (MnPCEs) and decrease in buccal mucosa phase II detoxication agents were noticed in tumor bearing hamsters. Oral administration of Withaferin-A significantly reduced the micronucleus frequency and brought back the status of phase II detoxication agents in DMBA painted hamsters. Our study thus demonstrated the protective effect of Withaferin-A on DMBA-induced micronucleus frequency in the bone marrow of golden Syrian hamsters. Also, Withaferin-A maintained the status of buccal mucosa detoxication agents during DMBA-induced hamster buccal pouch carcinogenesis.Key words: Withaferin-A, DMBA, Oral cancer, Micronucleus, Detoxicatio

    NUMERICAL EXPERIMENT ON EFFECT OF SURFACE ROUGHNESS FOR HEAT AND FLOW AROUND TWO CONTACTING PARTICLES

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    The aim of the present work is to establish a model of heat transfer between particles by using the numerical simulation that can be incorporated in the discrete element method (DEM). The contact heat transfer between particles can be regarded as a contact thermal resistance problem. In the thermal resistance model, the local characteristics, e.g. exact contact area and heat flux distribution on particle surface, are important. However, it is difficult to measure such factors in detail. Accordingly, the authors utilized a numerical simulation. The thermal resistance was modeled by placing a small solid block between the contacting areas in the simulation. The small solid thickness represents the surface roughness and the width represents the contact force. The simulated temperature profile along the center line through two particle’s centers well agreed with measured one

    Willmore Surfaces of Constant Moebius Curvature

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    We study Willmore surfaces of constant Moebius curvature KK in S4S^4. It is proved that such a surface in S3S^3 must be part of a minimal surface in R3R^3 or the Clifford torus. Another result in this paper is that an isotropic surface (hence also Willmore) in S4S^4 of constant KK could only be part of a complex curve in C2≅R4C^2\cong R^4 or the Veronese 2-sphere in S4S^4. It is conjectured that they are the only examples possible. The main ingredients of the proofs are over-determined systems and isoparametric functions.Comment: 16 pages. Mistakes occured in the proof to the main theorem (Thm 3.6) has been correcte

    Space-times which are asymptotic to certain Friedman-Robertson-Walker space-times at timelike infinity

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    We define space-times which are asymptotic to radiation dominant Friedman-Robertson-Walker space-times at timelike infinity and study the asymptotic structure. We discuss the local asymptotic symmetry and give a definition of the total energy from the electric part of the Weyl tensor.Comment: 8 pages, Revte

    Effects of lean combustion on bioethanol-gasoline blends using turbocharged spark ignition engine

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    Liquid alternative fuels have been utilised as engine fuel since the 19th century. For several alternative fuels, bioethanol is well-known as the most suited friendly, alternative-product based and renewable for use in spark-ignition (SI) engines. In addition, it is well known that bioethanol has higher evaporation of heat, research octane number and flammability of temperature; therefore, it has a greater influence on performance and lower emission. In this study, the effect of gasoline fuel RON95 (G) was blended into bioethanol fuel (E10, E20 and E30) to investigate the engine combustion, performance and emission. The engine used was 1.8L Mitsubishi, four-cylinder, four-stroke, multipoint port injection and turbocharger SI. The engine speed used was 1000-3000 rpm at 10-40% load with wide-open throttle (WOT). The results showed that bioethanol addition to gasoline increases the brake torque at a higher load. The mass fraction burn (MFB) and coefficient of variation (COV) blend fuel and main fuel are comparable to each other. The brake specific fuel consumption (BSFC) significantly increases when engine speed increases. The emission of nitrogen oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC) emissions reduced dramatically compared to gasoline fuel. Indeed, bioethanol-gasoline fuel allows the engine utilised in low proportion to increase engine performance and lower engine emission

    Complexity of Bradley-Manna-Sipma Lexicographic Ranking Functions

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    In this paper we turn the spotlight on a class of lexicographic ranking functions introduced by Bradley, Manna and Sipma in a seminal CAV 2005 paper, and establish for the first time the complexity of some problems involving the inference of such functions for linear-constraint loops (without precondition). We show that finding such a function, if one exists, can be done in polynomial time in a way which is sound and complete when the variables range over the rationals (or reals). We show that when variables range over the integers, the problem is harder -- deciding the existence of a ranking function is coNP-complete. Next, we study the problem of minimizing the number of components in the ranking function (a.k.a. the dimension). This number is interesting in contexts like computing iteration bounds and loop parallelization. Surprisingly, and unlike the situation for some other classes of lexicographic ranking functions, we find that even deciding whether a two-component ranking function exists is harder than the unrestricted problem: NP-complete over the rationals and ÎŁ2P\Sigma^P_2-complete over the integers.Comment: Technical report for a corresponding CAV'15 pape

    Deformable unsaturated laterite soil under vibration impact with dissimilar moisture content

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    Vibrations from vehicle traffic, machinery and operations from construction activities such as blasting are examples of some natural and man-made vibration phenomenon's that can cause dynamic stress when imposed onto soils. In order to ensure sustainability of the geo-environment, the impacts caused by these vibrations as well as the changes in moisture content needs to be addressed. To achieve this, the behaviour of vibrated deformable double-porosity under dissimilar moisture content in non-repeated vibration was assessed and characterized through laboratory experiments. Investigation of deformable unsaturated laterite soil by aggregating laterite soil using 29%, 30%, 32% and 34% moisture content was carried out and presented in this paper. An acrylic soil column, accelerometer and vibrating table were used to conduct the experiments. The acrylic columns were filled with each aggregated soil and the soil was then compressed to a height of 10 cm, which had been pre-determined beforehand. Accelerometers were installed to a vibrating table where each soil column was tested to measure the time histories of high-frequency acceleration on the surfaces of both the laterite soil and vibrating table. Acceleration was observed at two points, namely; (1) the surface of the soil sample and (2) the surface of the vibrating table. The amplitude of the vibrating table was increased in order to test for repeated vibration. Maximum amplitudes were recorded by collecting the acceleration time histories and the amplitude of displacement was increased in order to carry out the tests. The outcome of the tests demonstrated that there was an increase of the acceleration response in non-repeated vibration when moisture contents were also increased. For the vibrated samples that were used, it was found that there was a rearrangement of the soils structure and as expected, the porosity characteristics that were identified had influenced the liquid penetrations' speed

    Smart Home Control for Disabled Using Brain Computer Interface

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    Electroencephalography (EEG) based smart home control system is one of the major applications of Brain Computer Interface (BCI) that allows disabled people to maximize their capabilities at home. A Brain Computer Interface (BCI) is a device that enables severely disabled people to communicate and interact with their environments using their brain waves. In this project, the scope includes Graphical User Interface (GUI) acts as a control and monitoring system for home appliances which using BCI as an input. Hence, NeuroSky MindWave headset is used to detect EEG signal from brain. Furthermore, a prototype model is developed using Raspberry Pi 3 Model B+, 4 channels 5V relay module, light bulb and fan. The raw data signal from brain wave is being extracted to operate the home appliances. Besides, the results agree well with the command signal used during the experiment. Lastly, the developed system can be easily implemented in smart homes and has high potential to be used in smart automation

    Evaluation of properties on performance and emission to turbocharged SI engine using fusel oil blend with gasoline

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    Biofuel has the potential to be used as an alternative fuel compared to petroleum gasoline for the purpose increase performance and reducing emissions. The objective of the study is to evaluate performance and emission on properties of 10–30% fusel oil blends with pure gasoline (Ron 95) at 3000 rpm. In this experiment, three fuels were designed from fusel oil to test engine performance and emission. The haltech ECU was an escalation to set ignition, injection timing and injection mass when using fusel oil blends to reach stoichiometric level. In this study, pure gasoline was set as a reference. The experiments were conducted on 1.8L turbocharged 4-cylinder, spark ignition engine, port injection and coupled with 100 kW eddy current dynamometer. During engine testing, the throttle position was applied to 10–40%. As a result, averaged BMEP increase at 11.9%, 17.8% and 21.3% for F10, F20 and F30 respectively compared to gasoline. The VE and BSFC averaged increased 8.3% and 6.17% compared to pure gasoline for 10–40% engine load. The emissions for CO and HC on these observations increased while the NOx decreased when fusel oil blends were utilized. The recommendation used in study is low proportion blends to assess different properties for engine test

    Monitoring Leachate Migration in Compacted Soil Using Digital Image Technique

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    As leachate has been a source of groundwater contamination worldwide, this paper examines the phenomenon of leachate migration on different gradations of compacted laterite soil used as sanitary landfill liners. Three different soil gradations (30%, 40% and 50% with respect to fines content) used in this study were compacted in circular acrylic columns to provide a clear visualization of leachate migration into the soils. Digital image technique was used in capturing photos at successive time intervals to monitor the leachate migration. The captured digital images were fed into Matlab and converted into hue-saturation-intensity (HSI) format. Surfer software then read the HSI and generated 2D contour plots. The results of the experiments showed that the leachate moves downward faster in the soil gradation with the least fines content. Hydraulic conductivity values decrease with increase in time duration and equally with increase in fines content. The hydraulic conductivities of the leachate for 30%, 40% and 50% fines were 3.64Ă—10-9m/s, 2.40Ă—10-9m/s, and 1.24Ă—10-9m/s respectively. This reveals that for tropical laterite soils, gradation containing 50% fines content provides better hydraulic conductivity. The use of noninvasive digital image technique can enable designers/engineers to monitor and visualize the leachate migration in compacted soils in waste containment application systems
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