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  • articleNo Access

    Single-particle and collective excitations in quantum wires comprised of vertically stacked quantum dots: Finite magnetic field

    A theoretical investigation has been made of the magnetoplasmon excitations in a quasi-one-dimensional electron system composed of vertically stacked, self-assembled InAs/GaAs quantum dots. The smaller length scales involved in the experiments impel us to consider a perfectly periodic system of two-dimensionally confined InAs quantum dot layers separated by GaAs spacers. Subsequent system is subjected to a two-dimensional confining (harmonic) potential in the xy plane and an applied magnetic field (B) in the symmetric gauge. This scheme defines virtually a system of quantum wire comprised of vertically stacked quantum dots (VSQD). We derive and discuss the Dyson equation, the generalized (nonlocal and dynamic) dielectric function, and the inverse dielectric function for investigating the single-particle and collective (magnetoplasmon) excitations within the framework of (full) random-phase approximation (RPA). As an application, we study the influence of the confinement potential and the magnetic field on the component eigenfunctions, the density of states (DOS), the Fermi energy, the collective excitations, and the inverse dielectric functions. How the B-dependence of DOS validate the VSQD mimicking the realistic quantum wires, the Fermi energy oscillates as a function of the Bloch vector, the intersubband single-particle continuum bifurcates at the origin, a collective excitation emerges and propagates within the gap of the split single-particle continuum, and the alteration in the well- and barrier-widths allows to customize the excitation spectrum in the desired energy range are some of the remarkable features of this investigation. These findings demonstrate, for the very first time, the significance of investigating the system of VSQD subjected to a quantizing magnetic field. Given the edge over the planar quantum dots and the foreseen applications in the single-electron devices and quantum computation, investigating the system of VSQD is deemed vital. The results suggest exploiting magnetoplasmon qubits to be a potential option for implementing the solemn idea of quantum state transfer in devising quantum gates for the quantum computation and quantum communication networks.

  • articleNo Access

    General Information & Statistics

      Innovative Food Center Launched.

      China Sets up National Stem Cell Base in Tianjin.

      Sino-US Collaboration on Drug Screening.

      Study Shows Insufficient Breast Cancer Awareness.

      Call for India to Modernize Farming Sector.

      Indian Biotech Sector Lacks Funding.

      Biotech Solutions Available Online.

      Local Governments Subsidize Fertility Treatment.

      Low Blood Selenium Levels in New Zealanders.

      NZ Biotech Should Focus on Environment.

      Singapore Sets up National Tissue Repository.

      Singapore Research Agency Appoints New Leaders.

      Institute to Use Nanoscience to Treat Diseases.

      Taiwan Establishes Botanical Drug Products Plant.

      Fatality Rate in Childbirth at High Level.

    • articleNo Access

      General Information & Statistics

        Australia’s Largest Dedicated Bioinformatics Computer Cluster Launched.

        Software Modeling Tool for Drug Development.

        Funding for Queensland Biotech Companies.

        China Sets up Nanoscience and Nanotech Center.

        Few Takers for Cipla’s Cheap Anti-AIDS Drugs.

        Indian Government Funds DNA Chip Project.

        Importer of Cancer Drug Iressa May Face Legal Suit.

        Recycled Bath Water Causes Fatal Lung Infection.

        Study into Occupational Cancer Given Boost.

        NZ Lacks Biotech Funding.

        First cGMP Biopharmaceutical Manufacturing Facility in the Region.

        One in Five Taiwanese Hypertensive.

        Biotech and Medical Park Approved.

      • articleNo Access

        BIOBOARD

          SINGAPORE – A New Way of Looking at Cancer

          SINGAPORE – Novel Discovery by NUS Scientists Improves Profiling of AML Patients for Targeted Therapies

          SINGAPORE – Red Meat Consumption Linked with Increased Risk of Developing Kidney Failure

          SINGAPORE – Thomson Medical and UK-based Cell Therapy Limited Collaborate on Stem Cell Research to Develop Regenerative Medicines

          UNITED STATES – New Biomaterial Developed for Injectable Neuronal Control

          UNITED STATES – Research Shines Light on Lesser Known Form of Vitamin D in Foods

          UNITED STATES – MRIGlobal to Lead International Research Collaboration for Tularemia Vaccine

          INDIA – Improving Agricultural Yield and Quality through Tissue Culture Technology

          TAIWAN – A Cascade of Protein Aggregation Bombards Mitochondria for Neurodegeneration and Apoptosis under WWOX Deficiency

        • articleNo Access

          EYE ON CHINA

            New births in China reached 18.5 million in 2016.

            2017 Future Science Prize winners announced: Yigong Shi, Jianwei Pan, Chenyang Xu.

            Smart nano-pesticide to combat soil and water contamination.

            Nanotech applications lag behind research output.

            China plans to launch “brain project” by year end.

            AliHealth builds up online pharmacy in China.

            Internet of Things for better health solutions.

            Knowledge sharing via the Digital Silk Road.

            UNAIDS encourages Chinese to produce drugs for Africa.

          • articleNo Access

            BEHAVIOR OF THE CONFINED HARD-SPHERE FLUID WITHIN NANOSLITS: A FUNDAMENTAL-MEASURE DENSITY-FUNCTIONAL THEORY STUDY

            A property of central interest for theoretical study of nanoconfined fluids is the density distribution of molecules. The density profile of the hard-sphere fluids confined within nanoslit pores is a key quantity for understanding the configurational behavior of confined real molecules. In this report, we produce the density profile of the hard-sphere fluid confined within nanoslit pores using the fundamental-measure density-functional theory (FM-DFT). FM-DFT is a powerful approach to studying the structure and the phase behavior of nanoconfined fluids. We report the computational procedure and the calculated data for nanoslits with different widths and for a wide range of hard-sphere fluid densities. The high accuracy of the resulting density profiles and optimum grid-size values in numerical integration are verified. The data reveal a number of interesting features of hard spheres in nanoslits, which are different from the bulk hard-sphere systems. These data are also useful for a variety of purposes, including obtaining the shear stress, thermal conductivity, adsorption, solvation forces, free volume and prediction of phase transitions.

          • articleNo Access

            DSETHVASAN: A NOVEL NANODRUG AGAINST SLEEPING SICKNESS

            Sleeping sickness (causal agent, Trypanosoma sp. parasite) causes huge morbidity and mortality in Africa (both human and livestock) in particular and zoo animals worldwide. Three of the four currently approved drugs (Pentamidine, Melarsoprol, Eflornithine, and Nifurtimox) were developed over 50 years ago. Current therapies are unsatisfactory due to unacceptable level of side effects. Pentamidine, an aromatic diamidine, safest so far, inhibits mitochondrial enzymes. Furthermore, it is effective only in early stages of infections and not on the later stage. Melarsoprol, practically insoluble in water, is very toxic and it is given intravenously (i.v.) for later stage infections only. Other drugs like eflornithine and nitfurtimox are also unsatisfactory for various reasons. Human serum derived high-density lipoprotein (HDL; not mouse or any other mammalian HDL) shows trypanolytic effect in vitro and in vivo on T. brucei. But the mechanism of action of human HDL is far from clear. In the absence of novel drug leads, nanodrugs might be valid options as nanoparticles show better accessibility to cells, supramolecular interactions due to enormous increase in surface area to volume ratio, altered partition coefficient, etc. Surface-modified hydrophobic microsilica (FS), mixture of micro- and nanosilica (Dsethvasan) and nanosilica (AL) were characterized by UV–Vis, DLS, SEM, EDAX, AFM, and XRD. Trypanosoma evansi collected from infected horses were injected in mice. Control infected mouse (n = 30) showed 100% mortality within 72±24 h of injection. Dsethvasan-treated mice (n = 30) survived for 192±24 h. FS-treated mice (n = 30) survived for 120±24 h but the AL-treated mice (n = 30) died within 72±24 h of inoculation like infected control. Hydrophobic Dsethvasan which consists of pure amorphous forms of micro- and nanosilica works better than FS (AL is not at all effective). Therefore, micro- and nanomixture of amorphous silica is best suited for treating Trypanosoma infection in mice. The possible role of ratio of higher to lower size class has been discussed.

          • articleNo Access

            QUANTUM TRANSPORT AND CURRENT-TRIGGERED DYNAMICS IN MOLECULAR TUNNEL JUNCTIONS

            The modelling of nanoelectronic systems has been the topic of ever increasing activity for nearly two decades. Yet, new questions, challenges and opportunities continue to emerge. In this article we review theoretical and numerical work on two new developments in the theory of molecular-scale electronics. First we review a density functional theory analysis within the Keldysh non-equilibrium Green function formalism to predict nonlinear charge transport properties of nanoelectronic devices. Next we review a recently developed quantum mechanical formalism of current-triggered nuclear dynamics. Finally we combine these theories to describe from first principles the inelastic current and the consequent molecular dynamics in molecular heterojunctions.

          • articleNo Access

            A Colorful Life: Scientific Achievements of Tomás Torres in the Fields of Phthalocyanines, Molecular Materials and Nanoscience

            Some of the most important achievements of Tomás Torres in the last few decades within the fields of Phthalocyanines and related compounds, Molecular Materials and Nanoscience are revised and his recognized international prestige in these areas highlighted on the occasion of his 65th birthday.

          • articleNo Access

            Physics of Gauge Fields in Quantum Nanosciences

            SPIN01 Sep 2020

            We review the formulation of gauge fields in terms of the frame of reference as well as the space in which the frame is defined. We highlighted some recent applications of gauge physics in the momentum space — in the modern fields of the spin Hall effect, the magnon Hall, the optical Magnus and the graphene valley Hall. General procedures of gauge transformation which lead to the construction of the gauge curvature and the equations of motion (EOM) are outlined. Central to this review is our intention to illustrate the impact of gauge physics on the past and future development of many new research fields emerging out of condensed matter physics, particularly in quantum nanosciences and nanoelectronics.

          • articleOpen Access

            Nanoscience — Potential and Threats

            As the world’s population continues to expand, scientists are working to address the energy needs and challenges that accompany growth with environmentally responsible approaches. Nanoscience is helping to provide solutions to energy and environmental concerns in a number of ways.

          • chapterNo Access

            Nanoscience — Potential and Threats

            As the world’s population continues to expand, scientists are working to address the energy needs and challenges that accompany growth with environmentally responsible approaches. Nanoscience is helping to provide solutions to energy and environmental concerns in a number of ways.