Search results for: force

Authors: L. A. Ostrovsky, Yu. A. Stepanyants

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Effect of Earth rotation on nonlinear waves is a practically important and theoretically challenging problem of fluid mechanics and geophysics. Whereas the large-scale, geostrophic processes such as Rossby waves are a classical object of oceanic and atmospheric physics, rotation effects on mesoscale waves are not well studied. In particular, the Coriolis force can radically modify the behavior of nonlinear internal gravity waves in the ocean having spatial scales of 1-10 kilometers and time durations of few hours. In the last decade, such a non-trivial behavior was observed more than once. Similar effects are possible for magnetic sound in the ionosphere. Here we outline the main physical peculiarities in the behavior of nonlinear internal waves due to the rotation effect and present some results of our recent studies. The consideration is based on the fourth-order equation derived by one of the authors as a rotation-modified Korteweg–de Vries (rKdV) equation which includes two types of dispersion: one is responsible for the finiteness of depth as in the classical KdV equation; another is due to the Coriolis effect. This equation is, in general, non-integrable; moreover, under the conditions typical of oceanic waves (positive dispersion parameter), it does not allow solitary solutions at all. In the opposite case (negative dispersion) which is possible for, e.g., magnetic sound, solitary solutions do exist and can form complex bound states (multisoliton). Another non-trivial properties of nonlinear internal waves with rotation include, to name a few, the ‘terminal’ damping of the initial KdV soliton disappearing in a finite time due to radiation losses caused by Earth’s rotation, and eventual transformation of a KdV soliton into a wave packet (an envelope soliton). The new results to be discussed refer to the interaction of a soliton with a long background wave. It is shown, in particular, that in this case internal solitons can exist since the radiation losses are compensated by energy pumping from the background wave. Finally, the relevant oceanic observations of rotation effect on internal waves are briefly described.

Keywords: Earth rotation, internal waves, nonlinear waves, solitons

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Authors: May Haggag, Ezzat Fahmy, Mohamed Abdel-Mooty, Sherif Safar

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Sandwich sections have a very complex nature due to variability of behavior of different materials within the section. Cracking, crushing and yielding capacity of constituent materials enforces high complexity of the section. Furthermore, slippage between the different layers adds to the section complex behavior. Conventional methods implemented in current industrial guidelines do not account for the above complexities. Thus, a throughout study is needed to understand the true behavior of the sandwich panels thus, increase the ability to use them effectively and efficiently. The purpose of this paper is to conduct numerical investigation using ANSYS software for the structural behavior of sandwich wall section under eccentric loading. Sandwich walls studied herein are composed of two RC faces, a foam core and linking shear connectors. Faces are modeled using solid elements and reinforcement together with connectors are modeled using link elements. The analysis conducted herein is nonlinear static analysis incorporating material nonlinearity, crashing and crushing of concrete and yielding of steel. The model is validated by comparing it to test results in literature. After validation, the model is used to establish extensive parametric analysis to investigate the effect of three key parameters on the axial force bending moment interaction diagram of the walls. These parameters are the concrete compressive strength, face thickness and number of shear connectors. Furthermore, the results of the parametric study are used to predict a coefficient that links the interaction diagram of a solid wall to that of a sandwich wall. The equation is predicted using the parametric study data and regression analysis. The predicted α was used to construct the interaction diagram of the investigated wall and the results were compared with ANSYS results and showed good agreement.

Keywords: sandwich walls, interaction diagrams, numerical modeling, eccentricity, reinforced concrete

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Authors: Simone Belli, Sergio Minniti, Valeria Santoro

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ICTs and technology transfer can benefit and move a country forward in economic and social development. However, ICT and access to the Internet have been inequitably distributed in most developing countries. In terms of science production and dissemination, this divide articulates itself also through the inequitable distribution of access to scientific knowledge and networks, which results in the exclusion of developing countries from the center of science. Developing countries are on the fringe of Science and Technology (S&T) production due not only to low investment in research but also to the difficulties to access international scholarly literature. In this respect, Open access (OA) initiatives and knowledge infrastructure represent key elements for both producing significant changes in scholarly communication and reducing the problems of developing countries. The spreading of the OA movement in the region, exemplified by the growth of regional and national initiatives, such as the creation of OA institutional repositories (e.g. SciELO and Redalyc) and the establishing of supportive governmental policies, provides evidence of the significant role that OA is playing in reducing the scientific gap between Latin American countries and improving their participation in the so-called ‘global knowledge commons’. In this paper, we map OA publications in Latin America and observe how Latin American countries are moving forward and becoming a leading force in widening access to knowledge. Our analysis, developed as part of the H2020 EULAC Focus research project, is based on mixed methods and consists mainly of a bibliometric analysis of OA publications indexed in the most important scientific databases (Web of Science and Scopus) and OA regional repositories, as well as the qualitative analysis of documents related to the main OA initiatives in Latin America. Through our analysis, we aim at reflecting critically on what policies, international standards, and best practices might be adapted to incorporate OA worldwide and improve the infrastructure of the global knowledge commons.

Keywords: open access, LAC countries, scientific publications, bibliometric analysis

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Authors: Sutapa Som Chaudhury, Chitrangada Das Mukhopadhyay

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Alzheimer’s disease is a well-known form of dementia since its discovery in 1906. Current Food and Drug Administration approved medications e.g. cholinesterase inhibitors, memantine offer modest symptomatic relief but do not play any role in disease modification or recovery. In last three decades many small molecules, chaperons, synthetic peptides, partial β-secretase enzyme blocker have been tested for the development of a drug against Alzheimer though did not pass the 3rd clinical phase trials. Here in this study, we designed a PEGylated, aminogenic, tripeptidic polymer with two different molecular weights based on the aggregation prone amino acid sequence 17-20 in amyloid beta (Aβ) 1-42. Being conjugated with poly-ethylene glycol (PEG) which self-assembles into hydrophilic nanoparticles, these PEGylated tripeptides constitute a very good drug delivery system crossing the blood brain barrier while the peptide remains protected from proteolytic degradation and non-specific protein interactions. Moreover, being completely aminogenic they would not raise any side effects. These peptide inhibitors were evaluated for their effectiveness against Aβ42 fibrillation at an early stage of oligomer to fibril formation as well as preformed fibril clearance via Thioflavin T (ThT) assay, dynamic light scattering analyses, atomic force microscopy and scanning electron microscopy. The inhibitors were proved to be safe at a higher concentration of 20µM by the reduction assay of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. Moreover, SHSY5Y neuroblastoma cells have shown a greater survivability when treated with the inhibitors following Aβ42 fibril and oligomer treatment as compared with the control Aβ42 fibril and/or oligomer treated neuroblastoma cells. These make the peptidic inhibitors a promising compound in the aspect of the discovery of alternative medication for Alzheimer’s disease.

Keywords: Alzheimer’s disease, alternative medication, amyloid beta, PEGylated peptide

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Authors: Erkingul Soltanaeva, Omyrkhan Abdimanuly, Alua Temirbolat

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In this article, the public and social functions of literature and art in the Republic of Kazakhstan were analyzed on the basis of formal and informal literary organizations. The external and internal, subjective and objective factors which influenced the modern literary process were determined. The literary forces, their consolidation, types of organization in the art of word were examined. The periods of the literary process as planning, organization, promotion, and evaluation and their leading forces and approaches were analyzed. The right point of view to the language and mentality of the society force will influence to the literary process. The Ministry of Culture, the Writers' Union of RK and various non-governmental organizations are having different events for the promotion of literary process and to glorify literary personalities in the entire territory of Kazakhstan. According to the cultural plan of different state administration, there was a big program in order to publish their literary encyclopedia, to glorify and distribute books of own poets and writers of their region to the country. All of these official measures will increase the reader's interest in the book and will also bring up people to the patriotic education and improve the status of the native language. The professional literary publications such as the newspaper ‘Kazakh literature’, magazine ‘Zhuldyz’, and journal ‘Zhalyn’ materials which were published in the periods 2013-2015 on the basis of statistical analysis of the Kazakh literature topical to the issues and the field of themes are identified and their level of connection with the public situations are defined. The creative freedom, relations between society and the individual, the state of the literature, the problems of advantages and disadvantages were taken into consideration in the same articles. The level of functions was determined through the public role of literature, social feature, personal peculiarities. Now the stages as the literature management planning, organization, motivation, as well as the evaluation are forming and developing in Kazakhstan. But we still need the development of literature management to satisfy the actual requirements of the today’s agenda.

Keywords: literature management, material, literary process, social functions

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Authors: I-Yun Cheng, Min-Yu Chiang, Shwu-Jen Chang, San-Yuan Chen

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Osteoarthritis (OA) is among the most challenging joint diseases, and as far as we know, there is currently no exact and effective cure for it because it has low self-repair ability due to lack of blood vessels and low cell density in articular cartilage. So far, there have been several methods developed to treat cartilage disorder. The most common method is to treat the high molecular weight of hyaluronic acid (HA) injection, but it will degrade after a period of time, so the patients need to inject HA repeatedly. In recent years, self-healing hydrogel has drawn considerable attention because it can recover its initial mechanical properties after damaged and further increase the lifetime of the hydrogel. Here, we aim to develop a self-healable composite hydrogel combined with magnetic microspheres to trigger glutathione(GSH) release for promoting cartilage repair. We use HA-cyclodextrin (CD) as host polymer and poly(acrylic acid)-ferrocene (pAA-Fc) as guest polymer to form the self-healable HA-pAA hydrogel by host and guest interaction where various graft amount of pAA-Fc (pAA:Fc= 1:2, 1:1.5, 1:1, 2:1, 4:1) was conducted to develop different mechanical strength hydrogel. The rheology analysis showed that the 4:1 of pAA-Fc has higher mechanical strength than other formulations. On the other hand, iron oxide nanoparticle, poly(lactic-co-glycolic acid) (PLGA) and polyethyleneimine (PEI) were used to synthesize porous magnetic microspheres via double emulsification water-in-oil-in-water (W/O/W) to increase GSH loading which acted as a reductant to control the hydrogel crosslink density and promote hydrogel self-healing. The results show that the porous magnetic microspheres can be loaded with 70% of GSH and sustained release about 50% of GSH after 24 hours. More importantly, the HA-pAA composite hydrogel can self-heal rapidly within 24 hours when suffering external force destruction by releasing GSH from the magnetic microspheres. Therefore, the developed the HA-pAA composite hydrogel combined with GSH-loaded magnetic microspheres can be in-vivo guided to damaged OA surface for inducing the cartilage repair by controlling the crosslinking of self-healing hydrogel via GSH release.

Keywords: articular cartilage, magnetic microsphere, osteoarthritis, self-healing hydrogel

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Authors: W. El-Alami, J. Araña, O. González Díaz, J. M. Doña Rodríguez

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The efficiency of the semiconductor TiO₂ needs to be improved to be an effective tool for pollutant removal. To improve the efficiency of this semiconductor, it is necessary to deepen the knowledge of the processes that take place on its surface. In this sense, the deactivation of the catalyst is one of the aspects considered relevant. In order to study this point, the processes of deactivation of TiO₂ during the gas phase degradation of ethanol have been studied. For this, catalysts with only the anatase phase (SA and PC100) and catalysts with anatase and rutile phases (P25 and P90) have been selected. In order to force the deactivation processes, different cycles have been performed, adding ethanol gas but avoiding the degradation of acetates to determine their effect on the process. The surface concentration of fluorine on the catalysts was semi-quantitatively determined by EDAX analysis. The photocatalytic experiments were done with four commercial catalysts (P25, SA, P90, and PC100) and the two fluoride catalysts indicated above. The interaction and photocatalytic degradation of ethanol were followed by Fourier transform infrared spectroscopy (FTIR). EDAX analysis has revealed the presence of sodium on the surface of fluorinated catalysts. In FTIR studies, it has been observed that the acetates adsorbed on the anatase phase in P25 and P90 give rise to electron transfer to surface traps that modify the electronic states of the semiconductor. These deactivation studies have also been carried out with fluorinated P25 and SA catalysts (F-P25 and F-SA) which have observed similar electron transfers but in the opposite direction during illumination. In these materials, it has been observed that the electrons present in the surface traps, as a consequence of the interaction Ti-F, react with the holes, causing a change in the electronic states of the semiconductor. In this way, deactivated states of these materials have been detected by different electron transfer routes. It has been identified that acetates produced from the degradation of ethanol in P25 and P90 are probably hydrated on the surface of the rutile phase. In the catalysts with only the anatase phase (SA and PC100), the deactivation is immediate if the acetates are not removed before adsorbing ethanol again. In F-P25 and F-SA has been observed that the acetates formed react with the sodium ions present on the surface and not with the Ti atoms because they are interacting with the fluorine.

Keywords: photocatalytic degradation, ethanol, TiO₂, deactivation process, F-P25

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Authors: Aniekan James Akpan, Inemesit Akpan Umoren, Uduak Iwok

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From prehistoric and primitive cultures, education was seen as a process of culture transmission by way of guiding children into becoming good members of their local communities. Even in modern cultures, education is seen as a systematic discipline aimed at cultivating genuine values to improve oneself and society. Without education, the chances of realizing the desired vision are marred as it is believed that nations that invest much in education are able to reap the desired benefits technologically, economically, socially, politically, and otherwise. In this sense, the moulding of character is considered the primary purpose of education, and until the audience of mass media through its various vehicles is seen as tools for improving the overall development of society. It is believed that a media-friendly person is likely to perform better than someone who is less friendly. This work, therefore, examines the role media play in educational development. As highlighted by the study, a summary of the functions of media shows that they widen horizon by acting as a liberating force, breaking distance, bonds, and transforming a traditional society into a modern one. With the use of technological development theory, agenda-setting theory as well as uses and gratification theory and multiple intelligence theory, the work identifies different ways in which mass media help in educational development and draws attention to the audience’s perception of media functions in terms of educational development. With a survey method and a population of 6,903,321 people, the work sampled 220 respondents using purposive technique drawn from rural communities in the South-South region of Nigeria. The work concludes that mass media are potent vehicles for teaching and learning and therefore recommends that government should provide basic infrastructures to the rural communities to aid full utilization of media potentials in educational development and equally urge media owners and practitioners to as a matter of urgency increase coverage time on issues bordering on education as it is done for political and other issues.

Keywords: educational, development, media usage, perception

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Authors: Dimitriya A. Mihaylova, Zlatka V. Valkova-Jarvis, Georgi L. Iliev

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One possible approach for maintaining the security of communication systems relies on Physical Layer Security mechanisms. However, in wireless time division duplex systems, where uplink and downlink channels are reciprocal, the channel estimate procedure is exposed to attacks known as pilot contamination, with the aim of having an enhanced data signal sent to the malicious user. The Shifted 2-N-PSK method involves two random legitimate pilots in the training phase, each of which belongs to a constellation, shifted from the original N-PSK symbols by certain degrees. In this paper, legitimate pilots’ offset values and their influence on the detection capabilities of the Shifted 2-N-PSK method are investigated. As the implementation of the technique depends on the relation between the shift angles rather than their specific values, the optimal interconnection between the two legitimate constellations is investigated. The results show that no regularity exists in the relation between the pilot contamination attacks (PCA) detection probability and the choice of offset values. Therefore, an adversary who aims to obtain the exact offset values can only employ a brute-force attack but the large number of possible combinations for the shifted constellations makes such a type of attack difficult to successfully mount. For this reason, the number of optimal shift value pairs is also studied for both 100% and 98% probabilities of detecting pilot contamination attacks. Although the Shifted 2-N-PSK method has been broadly studied in different signal-to-noise ratio scenarios, in multi-cell systems the interference from the signals in other cells should be also taken into account. Therefore, the inter-cell interference impact on the performance of the method is investigated by means of a large number of simulations. The results show that the detection probability of the Shifted 2-N-PSK decreases inversely to the signal-to-interference-plus-noise ratio.

Keywords: channel estimation, inter-cell interference, pilot contamination attacks, wireless communications

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Authors: Mindaugas Zavalis

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Analysis of experimental tests data of bending one-way reinforced concrete slabs from various articles of science revealed that voided slabs with a grid of hollow plastic inserts inside have smaller mechani-cal and physical parameters compared to continuous cross-section slabs (solid slabs). The negative influence of a reinforced concrete slab is impacted by hollow plastic inserts, which make a grid of voids in the middle of the cross-sectional area of the reinforced concrete slab. A formed grid of voids reduces the slab’s stiffness, which influences the slab’s parameters of serviceability, like deflection and cracking. Prima-ry investigation of data established during experiments illustrates that cracks occur faster in the tensile surface of the voided slab under bend-ing compared to bending solid slab. It means that the crack bending moment force for the voided slab is smaller than the solid slab and the reduction can variate in the range of 14 – 40 %. Reduce of resistance to cracking can be controlled by changing a lot of factors: the shape of the plastic hallow insert, plastic insert height, steps between plastic in-serts, usage of prestressed reinforcement, the diameter of reinforcement bar, slab effective depth, the bottom cover thickness of concrete, effec-tive cross-section of the concrete area about reinforcement and etc. Mentioned parameters are used to evaluate crack width and step of cracking, but existing analytical calculation methods for cracking eval-uation of voided slab with plastic inserts are not so exact and the re-sults of cracking evaluation in this paper are higher than the results of analyzed experiments. Therefore, it was made analytically calculations according to experimental bending tests of voided reinforced concrete slabs with hollow plastic inserts to find and propose corrections for the evaluation of cracking for reinforced concrete voided slabs with hollow plastic inserts.

Keywords: voided slab, cracking, hallow plastic insert, bending, one-way reinforced concrete, serviceability

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Authors: Ben Nadler

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Cell adhesion plays a vital role in many cell activities. The motivation to model cell adhesion is to study important biological processes, such as cell spreading, cell aggregation, tissue formation, and cell adhesion, which are very challenging to study by experimental methods alone. This study provides important insight into cell adhesion, which can lead to improve regenerative medicine and tissue formation techniques. In this presentation the biological cells adhesion is mediated by receptors–ligands binding and the diffusivity of the receptor on the cell membrane surface. The ability of receptors to diffuse on the cell membrane surface yields a very unique and complicated adhesion mechanism, which is exclusive to cells. The phospholipid bilayer, which is the main component in the cell membrane, shows fluid-like behavior associated with the molecules’ diffusivity. The biological cell is modeled as a fluid-like membrane with negligible bending stiffness enclosing the cytoplasm fluid. The in-plane mechanical behavior of the cell membrane is assumed to depend only on the area change, which is motivated by the fluidity of the phospholipid bilayer. In addition, the presence of receptors influences on the local mechanical properties of the cell membrane is accounted for by including stress-free area change, which depends on the receptor density. Based on the physical properties of the receptors and ligands the attraction between the receptors and ligands is modeled as a charged-nonpolar which is a noncovalent interaction. Such interaction is a short-range type, which decays fast with distance. The mobility of the receptor on the cell membrane is modeled using the diffusion equation and Fick’s law is used to model the receptor–receptor interactions. The resultant interaction force, which includes receptor–ligand and receptor–receptor interaction, is decomposed into tangential part, which governs the receptor diffusion, and normal part, which governs the cell deformation and adhesion. The formulation of the governing equations and numerical simulations will be presented. Analysis of the adhesion characteristic and properties are discussed. The roles of various thermomechanical properties of the cell, receptors and ligands on the cell adhesion are investigated.

Keywords: cell adhesion, cell membrane, receptor-ligand interaction, receptor diffusion

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Authors: Rajasekar Elangopandian, Anand Shanmugam

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In order to reduce the cost of launching satellite and payloads to the orbit this project envisages some immense combined technology. This new technology in space odyssey contains literally four concepts. The first mode in this innovation is flight mission characteristics which, says how the mission will induct. The conventional technique of magnetic levitation will help us to produce the initial thrust. The name states reusable launch vehicle shows its viability of reuseness. The flight consists miniature rocket which produces the required thrust and the two JATO (jet assisted takeoff) boosters which gives the initial boost for the vehicle. The vehicle ostensibly looks like an airplane design and will be located on the super conducting rail track. When the high power electric current given to the rail track, the vehicle starts floating as per the principle of magnetic levitation. If the flight reaches the particular takeoff distance the two boosters gets starts and will give the 48KN thrust each. Obviously it`ll follow the vertical path up to the atmosphere end/start to space. As soon as it gets its speed the two boosters will cutoff. Once it reaches the space the inbuilt spacecraft keep the satellite in the desired orbit. When the work finishes, the apogee motors gives the initial kick to the vehicle to come in to the earth’s atmosphere with 22N thrust and automatically comes to the ground by following the free fall, the help of gravitational force. After the flying region it makes the spiral flight mode then gets landing where the super conducting levitated rail track located. It will catch up the vehicle and keep it by changing the poles of magnets and varying the current. Initial cost for making this vehicle might be high but for the frequent usage this will reduce the launch cost exactly half than the now-a-days technology. The incorporation of such a mechanism gives `hybrid` and the reusability gives `reusable launch vehicle` and ultimately Hybrid reusable launch vehicle.

Keywords: the two JATO (jet assisted takeoff) boosters, magnetic levitation, 48KN thrust each, 22N thrust and automatically comes to the ground

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Authors: H. Daaou Nedjari, O. Guerri, M. Saighi

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A numerical study was conducted to optimize the positioning of wind turbines over complex terrains. Thus, a two-dimensional disk model was used to calculate the flow velocity deficit in wind farms for both flat and complex configurations. The wind turbine wake was assessed using the hybrid methods that combine CFD (Computational Fluid Dynamics) with the actuator disc model. The wind turbine rotor has been defined with a thrust force, coupled with the Navier-Stokes equations that were resolved by an open source computational code (Code_Saturne V3.0 developed by EDF) The simulations were conducted in atmospheric boundary layer condition considering a two-dimensional region located at the north of Algeria at 36.74°N longitude, 02.97°E latitude. The topography elevation values were collected according to a longitudinal direction of 1km downwind. The wind turbine sited over topography was simulated for different elevation variations. The main of this study is to determine the topography effect on the behavior of wind farm wake flow. For this, the wake model applied in complex terrain needs to selects the singularity effects of topography on the vertical wind flow without rotor disc first. This step allows to determine the existence of mixing scales and friction forces zone near the ground. So, according to the ground relief the wind flow waS disturbed by turbulence and a significant speed variation. Thus, the singularities of the velocity field were thoroughly collected and thrust coefficient Ct was calculated using the specific speed. In addition, to evaluate the land effect on the wake shape, the flow field was also simulated considering different rotor hub heights. Indeed, the distance between the ground and the hub height of turbine (Hhub) was tested in a flat terrain for different locations as Hhub=1.125D, Hhub = 1.5D and Hhub=2D (D is rotor diameter) considering a roughness value of z0=0.01m. This study has demonstrated that topographical farm induce a significant effect on wind turbines wakes, compared to that on flat terrain.

Keywords: CFD, wind turbine wake, k-epsilon model, turbulence, complex topography

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Authors: Maryam S. Ghoraishi, John E. Hawk, Thomas Thundat

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Understanding liquid properties in small scale has become important in recent decades as immerging new microelectromechanical systems (MEMS) devices have been widely used for micro pumps, drug delivery, and many other laboratory-on-microchips analysis. Often in microfluidic devices, fluids are transported electrokinetically. Therefore, extensive knowledge of fluid flow, heat transport, electrokinetics and electrochemistry are key to successful lab on a chip design. Among different microfluidic devices, recently developed hollow channel cantilever offers an ideal platform to study different fluid properties simultaneously without drastic decrease in quality factor which normally occurs when traditional cantilevers operate in the liquid phase. Using hollow channel cantilever, we monitor changes in density and viscosity of liquid while simultaneously investigating dielectric properties of alcohol water binary mixtures. Considerable research has been conducted on alcohol-water mixtures since such a mixture is a typical prototype for biomolecules, Micelle formation, and structural stability of proteins (to name a few). Here we show that hollow channel cantilever can be employed to investigate dielectric properties of ethanol/water mixtures in different concentrations. We study dynamic amplitude shifts of hollow channel cantilever oscillation at different concentrations of ethanol/water for different voltages. Our results show how interactions between solute and solvent, and possibly cluster formation, could change dielectric properties and dipole reorientation of the mixture, as well as the resulting force on the hollow cantilever. For comparison, we also examine higher conductivity ionic mixtures of sodium sulfate solution under the same conditions as low conductivity ethanol/water mixtures. We will show the results from systematic investigation of solvent effects on dielectric properties of the binary mixture. We will also address the question of resolution limits in dielectric study of analyte molecules imposed by solvent concentrations.

Keywords: dielectric constant, cantilever sensors, ethanol water mixtures, low frequency

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Authors: Benjamin Newman

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The picture of an adverse contest between two parties has often been used as an archetypal description of the Anglo-American adversarial criminal trial. However, in actuality, guilty pleas and plea-bargains have been dominating the procedure for over the last half-a-century. Characterised by two adverse parties, the court adjudicative system in the Anglo-American world adhere to the adversarial procedure, and while further features have been attributed and the values that are embedded within the procedure vary, it is a system that we have no adequate theory. Damaska had argued that the adversarial conflict-resolution mode of administration of justice stems from a liberal laissez-faire concept of a value neutral liberal state. Having said that, the court’s neutrality has been additionally rationalised in light of its liberal end as a safeguard from the state’s coercive force. Both conceptions of the court’s neutrality conflict in cases where the by-standing role disposes of its liberal duty in safeguarding the individual. Such is noticeable in plea bargains, where the defendant has the liberty to plead guilty, despite concerns over wrongful convictions and deprivation of liberty. It is an inner liberal tension within the notion of criminal adversarialism, between the laissez-faire mode which grants autonomy to the parties and the safeguarding liberal end of the trial. Langbein had asserted that the adversarial system is a criminal procedure for which we have no adequate theory, and it is by reference to political and moral theories that the research aims to articulate a normative account. The paper contemplates on the above liberal-tension, and by reference to Duff’s ‘calling-to-account’ theory, argues that autonomy is of inherent value to the criminal process, being considered a constitutive element in the process of being called to account. While the aspiration is that the defendant’s guilty plea should be genuine, the guilty-plea decision must be voluntary if it is to be considered a performative act of accountability. Thus, by valuing procedural autonomy as a necessary element within the criminal adjudicative process, it assimilates a liberal procedure, whilst maintaining the liberal end by holding the defendant to account.

Keywords: liberal theory, adversarial criminal procedure, criminal law theory, liberal perfectionism, political liberalism

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Authors: Dahiru Jafaru Usman

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Nigerian courts have been sanctioned by a plethora of authorities to always employ the literal rule in interpreting statutes where the language of the statute is clear and unambiguous. This cardinal rule of interpretation appears not to be employed on Shari'ah issues in Nigeria. This is more pronounced in the interpretation of the jurisdiction of the Shari'ah Court of Appeal (hereinafter the court). The paper doctrinally assesses the judicial attitude of Nigerian appellate courts towards the construction of Section 277 of the 1999 Constitution as amended and other relevant statutory enactments by the State Houses of Assembly. The paper argues that a careful examination of the wordings of the constitution on the jurisdiction of the court literally reveals the intention of the constitutional drafters empowering the National Assembly and States' House of Assemblies to add to the itemised jurisdictional areas of the court other matters not mentioned. The paper found that the appellate courts failed in their construction of the constitutional provisions to accord the words and phrases used in the establishment, jurisdiction, and quorum sections of the court their ordinary and grammatical meaning. This results in consistent limitation of the jurisdiction of the court to matters of Islamic personal law. This remains so even when Decree No. 26 of 1986 was in force suspending and amending the provisions of the 1979 Constitution deleting the word 'personal' in the suspended Nigerian Constitutions. In order not to render section 277 futile, the paper recommends that appellate courts in Nigeria should as required by rules of statutory interpretation adopt literal and ordinary grammatical meaning in interpreting constitutional provisions on the jurisdiction of the court. It is further recommended that appellate courts must interpret the provisions of the 1999 constitution in a manner not to frustrate the several decades' yearnings of the Muslims for a court that would hear all their appellate criminal and civil matters on the path of Shari'ah from the lowest court to the highest. This is a duty the Nigerian Supreme Court placed on their shoulders.

Keywords: interpretation of statutes, jurisdiction, literal rule, Nigeria, Shari'ah Court of Appeal, 1999 Constitution

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Authors: Sonam Chorol, Sharvan Kumar, Pritam Mukhopadhyay

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In biology, supramolecular systems require the use of chemical fuels to stay in sustained nonequilibrium steady states termed dissipative self-assembly in contrast to synthetic self-assembly. Biomimicking these natural dynamic systems, some studies have demonstrated artificial self-assembly under nonequilibrium utilizing various forms of energies (fuel) such as chemical, redox, and pH. Naphthalene diimides (NDIs) are well-known organic molecules in supramolecular architectures with high electron affinity and have applications in controlled electron transfer (ET) reactions, etc. Herein, we report the endergonic ET from tetraphenylborate to highly electron-deficient phosphonium NDI²+ dication to generate NDI•+ radical. The formation of radicals was confirmed by UV-Vis-NIR absorption spectroscopy. Electron-donor and electron-acceptor energy levels were calculated from experimental electrochemistry and theoretical DFT analysis. The HOMO of the electron donor locates below the LUMO of the electro-acceptor. This indicates that electron transfer is endergonic (ΔE°ET = negative). The endergonic ET from NaBPh₄ to NDI²+ dication was achieved thermodynamically by the formation of coupled biphenyl product confirmed by GC-MS analysis. NDI molecule bearing octyl phosphonium at the core and H-bond forming imide moieties at the axial position forms a gel. The rheological properties of purified radical ion NDI⦁+ gels were evaluated. The atomic force microscopy studies reveal the formation of large branching-type networks with a maximum height of 70-80 nm. The endergonic ET from NaBPh₄ to NDI²+ dication was used to design the assembly and disassembly redox reaction cycle using reducing (NaBPh₄) and oxidizing agents (Br₂) as chemical fuels. A part of NaBPh₄ is used to drive assembly, while a fraction of the NaBPh₄ is dissipated by forming a useful product. The system goes back to the disassembled NDI²+ dication state with the addition of Br₂. We think bioinspired dissipative self-assembly is the best approach to developing future lifelike materials with autonomous behavior.

Keywords: Ionic-gel, redox-cycle, self-assembly, useful product

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Authors: Yukinori Taniguchi, Kazuyoshi Kurita, Kohei Mizuta, Keigo Nishitani, Ryuichi Fukuda

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Tungsten carbide is widely used as a tool material in metal manufacturing process. Since tungsten is typical rare metal, establishment of recycle process of tungsten carbide tools and restore into cemented carbide material bring great impact to metal manufacturing industry. Recently, recycle process of tungsten carbide has been developed and established gradually. However, the demands for quality of cemented carbide tool are quite severe because hardness, toughness, anti-wear ability, heat resistance, fatigue strength and so on should be guaranteed for precision machining and tool life. Currently, it is hard to restore the recycled tungsten carbide powder entirely as raw material for new processed cemented carbide tool. In this study, to suggest positive use of recycled tungsten carbide powder, we have tried to fabricate a carbon based sintered steel which shows reinforced mechanical properties with recycled tungsten carbide powder. We have made set of newly designed sintered steels. Compression test of sintered specimen in density ratio of 0.85 (which means 15% porosity inside) has been conducted. As results, at least 1.7 times higher in nominal strength in the amount of 7.0 wt.% was shown in recycled WC powder. The strength reached to over 600 MPa for the Fe-WC-Co-Cu sintered alloy. Wear test has been conducted by using ball-on-disk type friction tester using 5 mm diameter ball with normal force of 2 N in the dry conditions. Wear amount after 1,000 m running distance shows that about 1.5 times longer life was shown in designed sintered alloy. Since results of tensile test showed that same tendency in previous testing, it is concluded that designed sintered alloy can be used for several mechanical parts with special strength and anti-wear ability in relatively low cost due to recycled tungsten carbide powder.

Keywords: tungsten carbide, recycle process, compression test, powder metallurgy, anti-wear ability

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Authors: Eiman Alqattan

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Kuwaiti criminal justice system’s responses to allegations of sexual violence against women during the pre-trial process, suggesting that the system in Kuwait is affected by an ethos that is male dominated and patriarchal, and which results in prejudicial, unfair, and unequal treatment of female victims of serious sexual offenses. Data derived from qualitative semi-structured face-to-face interviews with four main groups of criminal justice system personnel in Kuwait (prosecutors, police investigators, police officers, and investigators) reveal the characteristics of a complaint of sexual violence that contribute to cases being either sent to court or dismissed. This proposed paper will suggest that Arab cultural views of women appear to influence and even shape the views, perceptions, and conduct of the interviewed Kuwaiti criminal justice system personnel regarding complaints of sexual violence made by citizens. Data from the interviews show how the image of the ‘modest woman’ that exists within Arabic cultural views and norms greatly contributes to shaping the characteristics of what the majority of the interviewed officials considered to be a ‘credible’ allegation of sexual violence. In addition, it is clear that the interviewees’ definitions of ‘modesty’ varied. Yet the problem is not only about the stereotypical perceptions of complainants or the consequences of those perceptions on the decision to send the case to court. These perceptions also affected the behaviours of criminal justice system personnel towards citizen complainants. When complainants’ allegations were questioned, investigators went as far as abusing the women verbally or physically, often in order to force them to withdraw the so-called ‘false’ complaint in order to protect the ‘real’ victim: the ‘innocent defendant’. The proposed presentation will discuss these police approaches to women and the techniques used in assessing the credibility of their accusations, including how they differ depending on whether the complainant was under or over 21 years old.

Keywords: criminal justice system, law and Arab culture, modest woman, sexual violence

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Authors: Aysel Mehdiyeva

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As a driving force of society, the role of teachers is important in inspiring, motivating, and encouraging the younger generation to protect the environment. In light of these, the study aims to explore teachers’ beliefs to understand teachers’ engagement with teaching about the environment. Though teachers’ beliefs about the environment have been explored by a number of researchers, the influence of these beliefs in their professional lives and in shaping their classroom instructions has not been widely investigated in Azerbaijan. To this end, this study aims to reveal the beliefs of secondary school geography teachers about the environment and find out the ways teachers’ beliefs of the environment are enacted in their classroom practice in Azerbaijan. Different frameworks have been suggested for measuring environmental beliefs stemming from well-known anthropocentric and biocentric worldviews. The study addresses New Ecological Paradigm (NEP) by Dunlap to formulate the interview questions as discussion with teachers around these questions aligns with the research aims serving to well-capture the beliefs of teachers about the environment. Despite the extensive applicability of the NEP scale, it has not been used to explore in-service teachers’ beliefs about the environment. Besides, it has been used as a tool for quantitative measurement; however, the study addresses the scale within the framework of the qualitative study. The research population for semi-structured interviews and observations was recruited via purposeful sampling. Teachers’ being a unit of analysis is related to the gap in the literature as to how teachers’ beliefs are related to their classroom instructions within the environmental context, as well as teachers’ beliefs about the environment in Azerbaijan have not been well researched. 6 geography teachers from 4 different schools were involved in the research process. The schools are located in one of the most polluted parts of the capital city Baku where the first oil well in the world was drilled in 1848 and is called “Black City” due to the black smoke and smell that covered that part of the city. Semi-structured interviews were conducted with the teachers to reveal their stated beliefs. Later, teachers were observed during geography classes to understand the overlap between teachers’ ideas presented during the interview and their teaching practice. Research findings aim to indicate teachers’ ecological beliefs and practice, as well as elaborate on possible causes of compatibility/incompatibility between teachers’ stated and observed beliefs.

Keywords: environmental education, anthropocentric beliefs, biocentric beliefs, new ecological paradigm

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Authors: Muhammad Umar Mushtaq, Muhammad Bilal Khan Niazi, Nouman Ahmad, Dooa Arif

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Apart from organic dyes, heavy metals such as Pb, Ni, Cr, and Cu are present in textile effluent and pose a threat to humans and the environment. Many studies on removing heavy metallic ions from textile wastewater have been conducted in recent decades using metal-organic frameworks (MOFs). In this study new polyether sulfone ultrafiltration membrane, modified with Cu/Co and Cu/Zn-based bimetal-organic frameworks (MOFs), was produced. Phase inversion was used to produce the membrane, and atomic force microscopy (AFM), scanning electron microscopy (SEM) were used to characterize it. The bimetallic MOFs-based membrane structure is complex and can be comprehended using characterization techniques. The bimetallic MOF-based filtration membranes are designed to selectively adsorb specific contaminants while allowing the passage of water molecules, improving the ultrafiltration efficiency. MOFs' adsorption capacity and selectivity are enhanced by functionalizing them with particular chemical groups or incorporating them into composite membranes with other materials, such as polymers. The morphology and performance of the bimetallic MOF-based membrane were investigated regarding pure water flux and metal ion rejection. The advantages of developed bimetallic MOFs based membranes for wastewater treatment include enhanced adsorption capacity because of the presence of two metals in their structure, which provides additional binding sites for contaminants, leading to a higher adsorption capacity and more efficient removal of pollutants from wastewater. Based on the experimental findings, bimetallic MOF-based membranes are more capable of rejecting metal ions from industrial wastewater than conventional membranes that have already been developed. Furthermore, the difficulties associated with operational parameters, including pressure gradients and velocity profiles, are simulated using Ansys Fluent software. The simulation results obtained for the operating parameters are in complete agreement with the experimental results.

Keywords: bimetallic MOFs, heavy metal ions, industrial wastewater treatment, ultrafiltration.

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Authors: Soukat Kumar Das

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Rapid industrialization and increase in population has resulted in the scarcity of suitable ground conditions. It has driven the need of ground improvement by means of reinforcement with geosynthetics with the minimum possible settlement and with maximum possible safety. Prestressing the geosynthetics offers an economical yet safe method of gaining the goal. Commercially available software PLAXIS 3D has made the analysis of prestressed geosynthetics simpler with much practical simulations of the ground. Attempts have been made so far to analyse the effect of prestressing geosynthetics and the effect of interference of footing on Unreinforced (UR), Geogrid Reinforced (GR) and Prestressed Geogrid Reinforced (PGR) soil on the load bearing capacity and the settlement characteristics of prestressed geogrid reinforced soil using the numerical analysis by using the software PLAXIS 3D. The results of the numerical analysis have been validated and compared with those given in the referred paper. The results have been found to be in very good agreement with those of the actual field values with very small variation. The GR soil has been found to be improve the bearing pressure 240 % whereas the PGR soil improves it by almost 500 % for 1mm settlement. In fact, the PGR soil has enhanced the bearing pressure of the GR soil by almost 200 %. The settlement reduction has also been found to be very significant as for 100 kPa bearing pressure the settlement reduction of the PGR soil has been found to be about 88 % with respect to UR soil and it reduced to up to 67 % with respect to GR soil. The prestressing force has resulted in enhanced reinforcement mechanism, resulting in the increased bearing pressure. The deformation at the geogrid layer has been found to be 13.62 mm for GR soil whereas it decreased down to mere 3.5 mm for PGR soil which certainly ensures the effect of prestressing on the geogrid layer. The parameter Improvement factor or conventionally known as Bearing Capacity Ratio for different settlements and which depicts the improvement of the PGR with respect to UR and GR soil and the improvement of GR soil with respect to UR soil has been found to vary in the range of 1.66-2.40 in the present analysis for GR soil and was found to be vary between 3.58 and 5.12 for PGR soil with respect to UR soil. The effect of prestressing was also observed in case of two interfering square footings. The centre to centre distance between the two footings (SFD) was taken to be B, 1.5B, 2B, 2.5B and 3B where B is the width of the footing. It was found that for UR soil the improvement of the bearing pressure was up to 1.5B after which it remained almost same. But for GR soil the zone of influence rose up to 2B and for PGR it further went up to 2.5B. So the zone of interference for PGR soil has increased by 67% than Unreinforced (UR) soil and almost 25 % with respect to GR soil.

Keywords: bearing, geogrid, prestressed, reinforced

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Authors: Samar Swaid

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Today, corporates are moving toward the adoption of Design-Thinking techniques to develop products and services, putting their consumer as the heart of the development process. One of the leading companies in Design-Thinking, IDEO (Innovation, Design, Engineering Organization), defines Design-Thinking as an approach to problem-solving that relies on a set of multi-layered skills, processes, and mindsets that help people generate novel solutions to problems. Design thinking may result in new ideas, narratives, objects or systems. It is about redesigning systems, organizations, infrastructures, processes, and solutions in an innovative fashion based on the users' feedback. Tim Brown, president and CEO of IDEO, sees design thinking as a human-centered approach that draws from the designer's toolkit to integrate people's needs, innovative technologies, and business requirements. The application of design thinking has been witnessed to be the road to developing innovative applications, interactive systems, scientific software, healthcare application, and even to utilizing Design-Thinking to re-think business operations, as in the case of Airbnb. Recently, there has been a movement to apply design thinking to machine learning and artificial intelligence to ensure creating the "wow" effect on consumers. The Association of Computing Machinery task force on Data Science program states that" Data scientists should be able to implement and understand algorithms for data collection and analysis. They should understand the time and space considerations of algorithms. They should follow good design principles developing software, understanding the importance of those principles for testability and maintainability" However, this definition hides the user behind the machine who works on data preparation, algorithm selection and model interpretation. Thus, the Data Science program includes design thinking to ensure meeting the user demands, generating more usable machine learning tools, and developing ways of framing computational thinking. Here, describe the fundamentals of Design-Thinking and teaching modules for data science programs.

Keywords: data science, design thinking, AI, currculum, transformation

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Authors: Ziwen Fang, Jianran Wang, Hongtao Liu, Weiguo Kong, Kefei Wang, Qi Luo, Haifeng Hong

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A 4-stage crash energy management (CEM) system for subway rail vehicles used by Massachusetts Bay Transportation Authority (MBTA) in the USA is developed in this paper. The 4 stages of this new CEM system include 1) energy absorbing coupler (draft gear and shear bolts), 2) primary energy absorbers (aluminum honeycomb structured box), 3) secondary energy absorbers (crush tube), and 4) collision post and corner post. A sliding anti-climber and a fixed anti-climber are designed at the front of the vehicle cooperating with the 4-stage CEM to maximize the energy to be absorbed and minimize the damage to passengers and crews. In order to investigate the effectiveness of this CEM system, both finite element (FE) methods and crashworthiness test have been employed. The whole vehicle consists of 3 married pairs, i.e., six cars. In the FE approach, full-scale railway car models are developed and different collision cases such as a single moving car impacting a rigid wall, two moving cars into a rigid wall, two moving cars into two stationary cars, six moving cars into six stationary cars and so on are investigated. The FE analysis results show that the railway vehicle incorporating this CEM system has a superior crashworthiness performance. In the crashworthiness test, a simplified vehicle front end including the sliding anti-climber, the fixed anti-climber, the primary energy absorbers, the secondary energy absorber, the collision post and the corner post is built and impacted to a rigid wall. The same test model is also analyzed in the FE and the results such as crushing force, stress, and strain of critical components, acceleration and velocity curves are compared and studied. FE results show very good comparison to the test results.

Keywords: railway vehicle collision, crash energy management design, finite element method, crashworthiness test

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Authors: Dheyaa W. Abbood, Rafa H. AL-Suhaili, May S. Saleh

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A model using the artificial neural networks and genetic algorithm technique is developed for obtaining optimum dimensions of the foundation length and protections of small hydraulic structures. The procedure involves optimizing an objective function comprising a weighted summation of the state variables. The decision variables considered in the optimization are the upstream and downstream cutoffs length sand their angles of inclination, the foundation length, and the length of the downstream soil protection. These were obtained for a given maximum difference in head, depth of impervious layer and degree of anisotropy.The optimization carried out subjected to constraints that ensure a safe structure against the uplift pressure force and sufficient protection length at the downstream side of the structure to overcome an excessive exit gradient. The Geo-studios oft ware, was used to analyze 1200 different cases. For each case the length of protection and volume of structure required to satisfy the safety factors mentioned previously were estimated. An ANN model was developed and verified using these cases input-output sets as its data base. A MatLAB code was written to perform a genetic algorithm optimization modeling coupled with this ANN model using a formulated optimization model. A sensitivity analysis was done for selecting the cross-over probability, the mutation probability and level ,the number of population, the position of the crossover and the weights distribution for all the terms of the objective function. Results indicate that the most factor that affects the optimum solution is the number of population required. The minimum value that gives stable global optimum solution of this parameters is (30000) while other variables have little effect on the optimum solution.

Keywords: inclined cutoff, optimization, genetic algorithm, artificial neural networks, geo-studio, uplift pressure, exit gradient, factor of safety

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Authors: P. Behera, K. K. Singh, D. K. Saini, M. De

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Implementation of 2D materials in the detection of bio analytes is highly advantageous in the field of sensing because of its high surface to volume ratio. We have designed our sensor array with different cationic two-dimensional MoS₂, where surface modification was achieved by cationic thiol ligands with different functionality. Green fluorescent protein (GFP) was chosen as signal transducers for its biocompatibility and anionic nature, which can bind to the cationic MoS₂ surface easily, followed by fluorescence quenching. The addition of bio-analyte to the sensor can decomplex the cationic MoS₂ and GFP conjugates, followed by the regeneration of GFP fluorescence. The fluorescence response pattern belongs to various analytes collected and transformed to linear discriminant analysis (LDA) for classification. At first, 15 different proteins having wide range of molecular weight and isoelectric points were successfully discriminated at 50 nM with detection limit of 1 nM. The sensor system was also executed in biofluids such as serum, where 10 different proteins at 2.5 μM were well separated. After successful discrimination of protein analytes, the sensor array was implemented for bacteria sensing. Six different bacteria were successfully classified at OD = 0.05 with a detection limit corresponding to OD = 0.005. The optimized sensor array was able to classify uropathogens from non-uropathogens in urine medium. Further, the technique was applied for discrimination of bacteria possessing resistance to different types and amounts of drugs. We found out the mechanism of sensing through optical and electrodynamic studies, which indicates the interaction between bacteria with the sensor system was mainly due to electrostatic force of interactions, but the separation of native bacteria from their drug resistant variant was due to Van der Waals forces. There are two ways bacteria can be detected, i.e., through bacterial cells and lysates. The bacterial lysates contain intracellular information and also safe to analysis as it does not contain live cells. Lysates of different drug resistant bacteria were patterned effectively from the native strain. From unknown sample analysis, we found that discrimination of bacterial cells is more sensitive than that of lysates. But the analyst can prefer bacterial lysates over live cells for safer analysis.

Keywords: array-based sensing, drug resistant bacteria, linear discriminant analysis, two-dimensional MoS₂

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Authors: Burdin Louise, Brulez Anne-Catherine, Mazurcyk Radoslaw, Leclercq Jean-louis, Benayoun Stéphane

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By using a biomimetic approach, an investigation was conducted to determine the connections between morphology and wetting. The interest is focused on the Morpho peleides butterfly. This butterfly is already well-known among researchers for its brilliant iridescent color and has inspired numerous innovations. The intricate structure of its wings is responsible for such color. However, this multiscale structure exhibits a multitude of other features, such as hydrophobicity. Given the limited research on the wetting properties of Morpho butterfly, a detailed analysis of its wetting behavior is proposed. Multiscale surface topographies of the Morpho peleides butterfly were analyzed using scanning electron microscope and atomic force microscopy. To understand the relationship between morphology and wettability, a goniometer was employed to measured static and dynamic contact angle. Since several studies have consistently demonstrated that superhydrophobic surfaces can effectively delay freezing, icing delay time the Morpho’s wings was also measured. The results revealed contact angles close to 136°, indicating a high degree of hydrophobicity. Moreover, sliding angles (SA) were measured in different directions, including along and against the rolling-outward direction. The findings suggest anisotropic wetting. Specifically, when the wing was tilted along the rolling outward direction (i.e., away from the insect’s body) SA was about 7°. While, when the wing was tilted against the rolling outward direction, SA was about 29°. This phenomenon is directly linked to the butterfly’s survival strategy. To investigate the exclusive morphological impact on anti-icing properties, PDMS replicas of the Morpho butterfly were obtained. When compared to flat PDMS and microscale textured PDMS, Morpho replications exhibited a longer freezing time. Therefore, this could be a source of inspiration for designing superhydrophobic surfaces with anti-icing applications or functional surfaces with controlled wettability.

Keywords: biomimetic, anisotropic wetting, anti-icing, multiscale roughness

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Authors: Frederic Heymes, Michael Albrecht Birk, Roland Eyssette

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Boiling Liquid Expanding Vapor Explosion (BLEVE) has been a well know industrial accident for over 6 decades now, and yet it is still poorly predicted and avoided. BLEVE is created when a vessel containing a pressure liquefied gas (PLG) is engulfed in a fire until the tank rupture. At this time, the pressure drops suddenly, leading the liquid to be in a superheated state. The vapor expansion and the violent boiling of the liquid produce several shock waves. This works aimed at understanding the contribution of vapor ad liquid phases in the overpressure generation in the near field. An experimental work was undertaken at a small scale to reproduce realistic BLEVE explosions. Key parameters were controlled through the experiments, such as failure pressure, fluid mass in the vessel, and weakened length of the vessel. Thirty-four propane BLEVEs were then performed to collect data on scenarios similar to common industrial cases. The aerial overpressure was recorded all around the vessel, and also the internal pressure changed during the explosion and ground loading under the vessel. Several high-speed cameras were used to see the vessel explosion and the blast creation by shadowgraph. Results highlight how the pressure field is anisotropic around the cylindrical vessel and highlights a strong dependency between vapor content and maximum overpressure from the lead shock. The time chronology of events reveals that the vapor phase is the main contributor to the aerial overpressure peak. A prediction model is built upon this assumption. Secondary flow patterns are observed after the lead. A theory on how the second shock observed in experiments forms is exposed thanks to an analogy with numerical simulation. The phase change dynamics are also discussed thanks to a window in the vessel. Ground loading measurements are finally presented and discussed to give insight into the order of magnitude of the force.

Keywords: phase change, superheated state, explosion, vapor expansion, blast, shock wave, pressure liquefied gas

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Authors: Nattaporn Khanoonkon, Rangrong Yoksan, Amod A. Ogale

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Polyethylene (PE) is one of the most petroleum-based thermoplastic materials used in many applications including packaging due to its cheap, light-weight, chemically inert and capable to be converted into various shapes and sizes of products. Although PE is a commercially potential material, its non-biodegradability caused environmental problems. At present, bio-based polymers become more interesting owing to its bio-degradability, non-toxicity, and renewability as well as being eco-friendly. Thermoplastic starch (TPS) is a bio-based and biodegradable plastic produced from the plasticization of starch under applying heat and shear force. In many researches, TPS was blended with petroleum-based polymers including PE in order to reduce the cost and the use of those polymers. However, the phase separation between hydrophobic PE and hydrophilic TPS limited the amount of TPS incorporated. The immiscibility of two different polarity polymers can be diminished by adding compatibilizer. PE-based compatibilizers, e.g. polyethylene-grafted-maleic anhydride, polyethylene-co-vinyl alcohol, etc. have been applied for the PE/TPS blend system in order to improve their miscibility. Until now, there is no report about the utilization of starch-based compatibilizer for PE/TPS blend system. The aims of the present research were therefore to synthesize a new starch-based compatibilizer, i.e. stearic acid-grafted starch (SA-g-starch) and to study the effect of SA-g-starch on chemical interaction, morphological properties, tensile properties and water vapor as well as oxygen barrier properties of the PE/TPS blend films. PE/TPS blends without and with incorporating SA-g-starch with a content of 1, 3 and 5 part(s) per hundred parts of starch (phr) were prepared using a twin screw extruder and then blown into films using a film blowing machine. Incorporating 1 phr and 3 phr of SA-g-starch could improve miscibility of the two polymers as confirmed from the reduction of TPS phase size and the good dispersion of TPS phase in PE matrix. In addition, the blend containing SA-g-starch with contents of 1 phr and 3 phr exhibited higher tensile strength and extensibility, as well as lower water vapor and oxygen permeabilities than the naked blend. The above results suggested that SA-g-starch could be potentially applied as a compatibilizer for the PE/TPS blend system.

Keywords: blend, compatibilizer, polyethylene, thermoplastic starch

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Authors: Josef Novák, Alena Kohoutková, Vladimír Křístek, Jan Vodička

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Numerical analysis software belong to the main tools for simulating the real behavior of various concrete structures and elements. In comparison with experimental tests, they offer an affordable way to study the mechanical behavior of structures under various conditions. The contribution deals with a precast element of an innovative airfield pavement system which is being developed within an ongoing scientific project. The proposed system consists a two-layer surface course of precast concrete panels positioned on a two-layer base of fiber-reinforced concrete with recycled aggregate. As the panels are supposed to be installed directly on the hardened base course, imperfections at the interface between the base course and surface course are expected. Considering such circumstances, three various behavior patterns could be established and considered when designing the precast element. Enormous costs of full-scale experiments force to simulate the behavior of the element in a numerical analysis software using finite element method. The simulation was conducted on a nonlinear model in order to obtain such results which could fully compensate results from the experiments. First, several loading schemes were considered with the aim to observe the critical one which was used for the simulation later on. The main objective of the simulation was to optimize reinforcement of the element subject to quasi-static loading from airplanes. When running the simulation several parameters were considered. Namely, it concerns geometrical imperfections, manufacturing imperfections, stress state in reinforcement, stress state in concrete and crack width. The numerical simulation revealed that the precast element should be heavily reinforced to fulfill all the demands assumed. The main cause of using high amount of reinforcement is the size of the imperfections which could occur at real structure. Improving manufacturing quality, the installation of the precast panels on a fresh base course or using a bedding layer underneath the surface course belong to the main steps how to reduce the size of imperfections and consequently lower the consumption of reinforcement.

Keywords: nonlinear analysis, numerical simulation, precast concrete, pavement

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