Synthesis of single-walled carbon nanotubes by induction thermal plasma

The production of high quality single-walled carbon nanotubes (SWCNTs) on a bulk scale has been an issue of considerable interest. Recently, it has been demonstrated that high quality SWCNTs can be continuously synthesized on large scale by using induction thermal plasma technology. In this process, the high energy density of the thermal plasma is employed to generate dense vapor-phase precursors for the synthesis of SWCNTs. With the current reactor system, a carbon soot product which contains approximately 40 wt% of SWCNTs can be continuously synthesized at the high production rate of ∼100 g/h. In this article, our recent research efforts to achieve major advances in this technology are presented. Firstly, the processing parameters involved are examined systematically in order to evaluate their individual influences on the SWCNT synthesis. Based on these results, the appropriate operating conditions of the induction thermal plasma process for an effective synthesis of SWCNTs are discussed. A characterization study has also been performed on the SWCNTs produced under the optimum processing conditions. Finally, a mathematical model of the process currently under development is described. The model will help us to better understand the synthesis of SWCNTs in the induction plasma process.      

Preparation and Characterization of Long Chain Branched Polypropylene through UV Irradiation and Coagent Use

Trimethylolpropane triacrylate as coagent was utilized along with benzophenone to modify polypropylene by generating long chain branches in the polypropylene molecular structure. The effects of trimethylolpropane triacrylate concentration, benzophenone concentration, and irradiation duration on viscoelastic properties and gel content were studied. The processing conditions that result in the greatest amount of long chain branching with minimum amount of gel content were identified. Gel permeation chromatography was used to confirm formation of branches and determine the branching content, whereas Fourier transform infrared spectroscopy confirmed the contribution of trimethylolpropane triacrylate in the formation of long chain branches.     

Finite-time control of spacecraft and hardware in the loop tuning

A nonlinear disturbance observer based on a super twisting controller is designed and implemented on the uncertain spacecraft attitude control subsystem simulator. The reaction wheels' angular momentum and their rate saturation are concerned in the controller design. The super twisting algorithm (STA) is devised in a way to make the reaction wheels into rest at the end of the maneuver. A nonlinear-disturbance-observer (NDO) is applied in estimating the external disturbances, unmodeled inertia moment, the eccentricity of rotation and mass center of simulator, and the reaction wheel saturation constraint. The finite-time stability of the closed-loop system is established according to the Lyapunov theory. The simulation and experimental results of this newly designed controller-observer on the spacecraft attitude simulator are compared in uncertain conditions.     

The Brownian and Flow‐Driven Rotational Dynamics of a Multicomponent DNA Origami‐Based Rotor

Nanomechanical devices are becoming increasingly popular due to the very diverse field of potential applications, including nanocomputing, robotics, and drug delivery. DNA is one of the most promising building materials to realize complex 3D structures at the nanoscale level. Several mechanical DNA origami structures have already been designed capable of simple operations such as a DNA box with a controllable lid, bipedal walkers, and cargo sorting robots. However, the nanomechanical properties of mechanically interlinked DNA nanostructures that are in general highly deformable have yet to be extensively experimentally evaluated. In this work, a multicomponent DNA origami‐based rotor is created and fully characterized by electron microscopy under negative stain and cryo preparations. The nanodevice is further immobilized on a microfluidic chamber and its Brownian and flow‐driven rotational behaviors are analyzed in real time by single‐molecule fluorescence microscopy. The rotation in previous DNA rotors based either on strand displacement, electric field or Brownian motion. This study is the first to attempt to manipulate the dynamics of an artificial nanodevice with fluidic flow as a natural force.     

Extending LaMer's mechanism using open system for increasing forced and controlled growth of Au nano particles: Desired decreasing Fe3O4 nano particles size during simultaneous synthesis in optimized conditions

The most effective parameters were found to obtain Au/Fe₃O₄ nano particles (NPs)-oleylamine composite. Having Au NPs with the controlled maximum mean size under the forced conditions was the main aim of this study. We used the continuous flow rates of oleylamine 75% to produce Au NPs under an open system by extended LaMer mechanisms. This process decreased the mean size of Fe₃O₄ NPs synthesized simultaneously, by classic LaMer mechanism. The Fe₃O₄ NPs production was carried out without continuous adding of any iron reactant, viz. as a closed system. In the absence of gold ions, the mean size of the synthesized Fe₃O₄ NPs using 2.5 ml/min oleylamine was about 35.0 nm at 2.0 ± 0.5 °C after 120 min. This mean size was decreased to 27.2, 21.4, 16.8 and 8.7 nm, when Au NPs were simultaneous prepared using 0.5, 0.75, 1.5 and 2.5 ml/min of oleylamine, respectively, at the same conditions. Surface Plasmon Resonance (SPR) adsorption was used to evaluate Au NPs production at first 30 min, while Small Angle X-ray Scattering (SAXS) method was used to monitor the reaction progression for near-real time analysis of increasing the growth of Au NPs up to 280 min, at the optimum conditions. Changing the properties of Fe₃O₄ NPs during processes was determined by studying Magnetization, Potentiometric titration, Inductive heating and Zeta potential.     

Chaos oscillator differential search combined with Pontryagin’s minimum principle for simultaneous power management and component sizing of PHEVs

Over the past decade, plug-in hybrid electric vehicles (PHEVs) have found a good reputation in the automotive industry due to the fact that they neatly satisfy the existing tight environmental regulations and fuel economy requirements. Recently, there has been more interest in the design optimization of the PHEV powertrains to improve their operational characteristics to the maximum possible extent. The PHEV powertrains are complicated systems and include different controllers and components which should operate corporately to guarantee the acceptable performance of the vehicle. The reported investigations indicate that improving the performance of PHEVs is a very arduous task because both control strategies and component sizes should be optimized in tandem; however, in most of the previous studies, the focus has been on improving one of the above-mentioned aspects, which does not result in the most efficient design. The main goal of the current study is to take advantage of a bi-level optimization framework which combines the optimizations of both powertrain component sizes and power management controller for a specific PHEV, namely 2012 Toyota plug-in Prius. The bi-level optimizer comprises a chaos-enhanced differential evolutionary algorithm, which is in charge of the component sizing, and a classical optimal control approach based on the Pontryagin’s minimum principle, which optimizes the vehicle power management strategy. A high-fidelity model of the vehicle is developed in the Autonomie software. This high-fidelity model is used to identify the parameters of a reduced model representing the vehicle dynamics by means of the homotopy analysis method, and the resulting model is then employed for the optimization procedure. The results of the numerical experiments indicate that by considering both component sizing and control strategy optimization, a very powerful tool is developed which can significantly improve the total fuel cost (F _C ), acceleration time (T _acc ), and battery state of charge (SOC) trajectory of the vehicle.     

Numerical study of temperature distribution in an inverse moving boundary problem using a meshless method

In this paper, we consider the inverse one-phase one-dimensional Stefan problem to study the thermal processes with phase change in a moving boundary problem and calculate the temperature distribution in the given domain, as well as approximate the temperature and the heat flux on a boundary of the region. For this problem, the location of the moving boundary and temperature distribution on this curve are available as the extra specifications. First, we use the Landau’s transformation to get a rectangular domain and then apply the Crank–Nicolson finite-difference scheme to discretize the time dimension and reduce the problem to a linear system of differential equations. Next, we employ the radial basis function collocation technique to approximate the spatial unknown function and its derivatives at each time level. Finally, the linear systems of algebraic equations constructed in this way are solved using the LU factorization method. To show the numerical convergence and stability of the proposed method, we solve two benchmark examples when the boundary data are exact or contaminated with additive noises.

     

A novel method to musicalize shape and visualize music and a novel technique in music cryptography

Since many years ago, musicians have composed music based on the images that they have had in their minds. On the other hand, music affects people’s imagination while hearing it. This research provides a method that can transform shape to music and music to shape. This method defines musical notations for horizontal, diagonal and vertical line segments, filled circle and curve with different colors, which are the basis of many shapes in transforming shapes into music. Then these primary mappings are generalized to more complex forms to transform any shape. Moreover, music can be transformed into shape by this method. For this transformation, primary musical notations such as simple notes, notes joined by a legato, notes with a staccato, notes joined by a legato and have crescendo or decrescendo and notes with an accent or a trill are defined. These primary musical notations are generalized to more complex forms to transform any music into shape. Also, the method of this research can be used in music cryptography. It employs mapping of notes in a twelve-tone equal musical system into shapes and mappings of shapes with an equal line width and different colors into music.

     

The Molecular Basis of COVID-19 Pathogenesis,Conventional and Nanomedicine Therapy

In late 2019, a new member of the Coronaviridae family, officially designated as “severe acute respiratory syndrome coronavirus 2” (SARS-CoV-2), emerged and spread rapidly. The Coronavirus Disease-19 (COVID-19) outbreak was accompanied by a high rate of morbidity and mortality worldwide and was declared a pandemic by the World Health Organization in March 2020. Within the Coronaviridae family, SARS-CoV-2 is considered to be the third most highly pathogenic virus that infects humans, following the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV). Four major mechanisms are thought to be involved in COVID-19 pathogenesis, including the activation of the renin-angiotensin system (RAS) signaling pathway, oxidative stress and cell death, cytokine storm, and endothelial dysfunction. Following virus entry and RAS activation, acute respiratory distress syndrome develops with an oxidative/nitrosative burst. The DNA damage induced by oxidative stress activates poly ADP-ribose polymerase-1 (PARP-1), viral macrodomain of non-structural protein 3, poly (ADP-ribose) glycohydrolase (PARG), and transient receptor potential melastatin type 2 (TRPM2) channel in a sequential manner which results in cell apoptosis or necrosis. In this review, blockers of angiotensin II receptor and/or PARP, PARG, and TRPM2, including vitamin D3, trehalose, tannins, flufenamic and mefenamic acid, and losartan, have been investigated for inhibiting RAS activation and quenching oxidative burst. Moreover, the application of organic and inorganic nanoparticles, including liposomes, dendrimers, quantum dots, and iron oxides, as therapeutic agents for SARS-CoV-2 were fully reviewed. In the present review, the clinical manifestations of COVID-19 are explained by focusing on molecular mechanisms. Potential therapeutic targets, including the RAS signaling pathway, PARP, PARG, and TRPM2, are also discussed in depth.