Transport Behavior
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Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2879
Amir Muhammad Afzal ◽  
Muhammad Farooq Khan ◽  
Jonghwa Eom

Transition metal dichalcogenide materials are studied to investigate unexplored research avenues, such as spin transport behavior in 2-dimensional materials due to their strong spin-orbital interaction (SOI) and the proximity effect in van der Waals (vdW) heterostructures. Interfacial interactions between bilayer graphene (BLG) and multilayer tungsten disulfide (ML-WS2) give rise to fascinating properties for the realization of advanced spintronic devices. In this study, a BLG/ML-WS2 vdW heterostructure spin field-effect transistor (FET) was fabricated to demonstrate the gate modulation of Rashba-type SOI and spin precession angle. The gate modulation of Rashba-type SOI and spin precession has been confirmed using the Hanle measurement. The change in spin precession angle agrees well with the local and non-local signals of the BLG/ML-WS2 spin FET. The operation of a spin FET in the absence of a magnetic field at room temperature is successfully demonstrated.

2021 ◽  
Vol 4 (1) ◽  
Ali Deniz Özdemir ◽  
Pramit Barua ◽  
Felix Pyatkov ◽  
Frank Hennrich ◽  
Yuan Chen ◽  

AbstractAll-carbon field-effect transistors, which combine carbon nanotubes and graphene hold great promise for many applications such as digital logic devices and single-photon emitters. However, the understanding of the physical properties of carbon nanotube (CNT)/graphene hybrid systems in such devices remained limited. In this combined experimental and theoretical study, we use a quantum transport model for field-effect transistors based on graphene electrodes and CNT channels to explain the experimentally observed low on currents. We find that large graphene/CNT spacing and short contact lengths limit the device performance. We have also elucidated in this work the experimentally observed ambipolar transport behavior caused by the flat conduction- and valence-bands and describe non-ideal gate-control of the contacts and channel region by the quantum capacitance of graphene and the carbon nanotube. We hope that our insights will accelerate the design of efficient all-carbon field-effect transistors.

2021 ◽  
Vol 25 (11) ◽  
pp. 5905-5915
Yaniv Edery ◽  
Martin Stolar ◽  
Giovanni Porta ◽  
Alberto Guadagnini

Abstract. Our study investigates interplays between dissolution, precipitation, and transport processes taking place across randomly heterogeneous conductivity domains and the ensuing spatial distribution of preferential pathways. We do so by relying on a collection of computational analyses of reactive transport performed in two-dimensional systems where the (natural) logarithm of conductivity is characterized by various degrees of spatial heterogeneity. Our results document that precipitation and dissolution jointly take place in the system, with the latter mainly occurring along preferential flow paths associated with the conductivity field and the former being observed at locations close to and clearly separated from these. High conductivity values associated with the preferential flow paths tend to further increase in time, giving rise to a self-sustained feedback between transport and reaction processes. The clear separation between regions where dissolution or precipitation takes place is imprinted onto the sample distributions of conductivity which tend to become visibly left skewed with time (with the appearance of a bimodal behavior at some times). The link between conductivity changes and reaction-driven processes promotes the emergence of non-Fickian effective transport features. The latter can be captured through a continuous-time random-walk model where solute travel times are approximated with a truncated power law probability distribution. The parameters of such a model shift towards values associated with increasingly high non-Fickian effective transport behavior as time progresses.

2021 ◽  
Vol 13 (22) ◽  
pp. 12391
Roman Roaljdovich Sidorchuk ◽  
Anastasia Vladimirovna Lukina ◽  
Sergey Vladimirovich Mkhitaryan ◽  
Irina Ivanovna Skorobogatykh ◽  
Anastasia Alexeevna Stukalova

This article presents a study of the attitude of metropolis residents to the environmental development of the urban public transport system. The authors set a goal to assess the influence of values on the assessment of environmental initiatives of city authorities in the field of public transport and their attitude to innovations in this sphere. In the course of the study, four clusters reflecting the values of the respondents were identified. The results showed support for innovations that do not require changes in the transport behavior of the individual. At the same time, we observe differences in the perception of initiatives by representatives of different clusters when the innovation affects their transportation behavior. Hypotheses were tested as an analysis result of empirical data by determining the synthetic indices of values using factor analysis, the classification of respondents based on the obtained indices to identify groups with similar values using cluster analysis, and an analysis of the relationship of the classification results by values using contingency tables and chi-square criterion. The scientific novelty of the study is to assess the impact of values of metropolis residents on the perception of environmental conditions and their change in the city.

2021 ◽  
Vol 1 ◽  
pp. 153-154
Daniel Glückman ◽  
Karin Hain ◽  
Claudia Joseph ◽  
Volker Metz ◽  
Francesca Quinto ◽  

Abstract. Clay rock is a potential host rock for the final disposal of nuclear waste in deep geological formations. In the scenario of ground water intrusion into the nuclear waste repository and subsequent corrosion of canisters and waste, possibly released actinides, such as uranium (U) and americium (Am), would be transported through the engineered barrier and clay host rock mainly by diffusion. Actinides are known to exhibit low solubility and are strongly sorbing under the reducing conditions of deep geological formations. Diffusion experiments are therefore difficult to perform due to analytical constraints. To our knowledge, the diffusion of U in clay rock has not been investigated below concentrations of 10-7molkg-1 clay (e.g., Joseph et al., 2013) and for Am, no diffusion experiments have been performed in a clay rock, considered suitable as host rock, such as Opalinus clay (OPA). This work aimed at the investigation of the diffusive behavior of U and Am down to ultra-trace concentrations (≪10-7molkg-1) in OPA. Laboratory-scale diffusion experiments were conducted with samples of OPA, obtained from the Mont Terri underground laboratory, Switzerland for up to 240 d. The OPA samples were placed in contact with synthetic pore water (I=0.22molL-1, pH=7.24), spiked with 5×10-9molL-1 of 233U and 243Am, respectively. After termination of the experiment, the OPA samples were segmented into thin layers of 20–400 µm. The obtained clay segments were analyzed for the 233U and 243Am content with accelerator mass spectrometry. Concentration profiles were determined down to 10-12molkg-1 clay for 233U and 5×10-10molkg-1 clay for 243Am. U showed a typical diffusion profile which can be interpreted by applying Fick's laws, while the Am profile was more complex, requiring further investigation of transport modes. These results will provide relevant insights into the transport behavior of U and Am in OPA over a wide range of concentrations down to ultra-trace levels.

2021 ◽  

Biomolecules and bionanoparticles, such as nucleic acids, proteins, microorganisms and extracellular vesicles (EVs), are recognized as important targets for fundamental research, clinical diagnostic and therapeutic applications. To gain detailed information of those bionanoparticles, we demonstrate an electroosmotic (EO) driven transport behavior in silicon and silicon nitride-based nanopore, towards an accurate measure of concentration and sizing of sub-micro particles for a general biological interest.

2021 ◽  
Harsh Patel ◽  

Abstract Nanocomposite membranes are a class of innovative filtering materials made up of nanofillers embedded in a polymeric or inorganic oxide matrix that functionalized for the membrane. Thermally rearranged (TR) polymers are found to have a good blending of selectivity and permeability. Chemical iridization is a process for used to make HAB-6FDA polyimide from 3,3 dihydroxy-4,4 diamino-biphenyl (HAB) & 2,2-bis-(3,4-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA). The sample is first changed from a pure polymer membrane to a silica nanofiller doped polymer layer and explain thermally rearrangement for gas permeability in polymer nanocomposite layers and its relationship with kinetic diameter of different gases. The selectivity is decreases as the permeability increases that shows on a trade-off relationship between permeability & selectivity. The CO2 permeability of the HAB-6FDA TR polymers is greater than that of other classes of polymers by equal free volume and indicating that these TR polymers have free volume distribution that supports high permeability. Thermally rearranged polymer nanocomposite exhibits higher gas permeability than that of silica doped and pure polymer. The selectivity for H2/N2 and H2/CO2 gas pairs exceeds towards Robeson's upper bound limit and in case of H2/CH4 gas pair this limit were crossed the Robeson’s upper bond limit. UV spectroscopy shows the change in transmission at higher wavelengths, while XRD show the reduction in FWHM with thermal treatment temperature. Polymer nanocomposite can be utilized to obtain high purity hydrogen gas for refinery and petrochemical applications.

2021 ◽  
Vol 13 (1) ◽  
Valentino Servizi ◽  
Francisco C. Pereira ◽  
Marie K. Anderson ◽  
Otto A. Nielsen

Abstract Background Although people and smartphones have become almost inseparable, especially during travel, smartphones still represent a small fraction of a complex multi-sensor platform enabling the passive collection of users’ travel behavior. Smartphone-based travel survey data yields the richest perspective on the study of inter- and intrauser behavioral variations. Yet after over a decade of research and field experimentation on such surveys, and despite a consensus in transportation research as to their potential, smartphone-based travel surveys are seldom used on a large scale. Purpose This literature review pinpoints and examines the problems limiting prior research, and exposes drivers to select and rank machine-learning algorithms used for data processing in smartphone-based surveys. Conclusion Our findings show the main physical limitations from a device perspective; the methodological framework deployed for the automatic generation of travel-diaries, from the application perspective; and the relationship among user interaction, methods, and data, from the ground truth perspective.

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