Synthesis and Properties of SrTiO3 Ceramic Doped with Sm2O3

The aim of this work was to study the effect of samarium oxide doping on a SrTiO3 perovskite ceramic. After analyzing the data obtained on the morphological features of the synthesized structures, it was found that an increase in the dopant concentration led not only to a change in the morphological features, but also in the density of the ferroelectrics. Using the X-ray diffraction method, it was found that doping with Sm2O3 led to the formation of a multiphase system of two cubic phases of SrTiO3 and Sm2O3. At the same time, an increase in the concentration of Sm2O3 dopant led to a change in the crystallinity degree, as well as deformation of the structure. Evaluation of the efficiency of use of synthesized ferroelectrics as catalysts for purification of aqueous media from manganese showed that an increase in the concentration of Sm2O3 dopant led to an increase in purification efficiency by 50–70%.

Study on The Effect of Solid Properties on The Hydrodynamics in an Ebullated Bed Reactor

Published data on the hydrodynamics of ebullated- bed reactors (EBRs) used in the H-Oil process are scarce. In the present work, the effect of solid properties (e.g., particle size, and degree of hydrophobicity) on the hydrodynamics and foaminess in a lab-scale cold model of an (EBR) was investigated. 20wt. % MgSO4 solution was utilized as the liquid phase to imitate the hydrodynamic trends in the industrial-scale EBR of the hydro-conversion process. Experimental results depicted that the flow regime of the multiphase system can be readily evaluated by using the pressure drop technique. The turning from the bubbly to the turbulent system is enhanced with diminishing particle size, and decreasing particle hydrophobicity. Moreover, the degree of particle hydrophobicity was inversely proportional to the average gas holdup in the EBR. The reduction in average gas holdup was 7.9 % using hydrophobic particles more than that of the hydrophilic one. In the EBR, it was found that bubble sizes were increased with both gas velocity and the axial location far from the gas distributor while liquid velocity has negative impact on bubble size. The experimental work revealed that hydrophobic particles of smaller size (250 μrm) reduced foaming by 70% using 20 vol. % of solid loading and gas and liquid velocities of 10 and 0.15 cm s-1 respectively. This outcome revealed that the surface of catalyst particles used can be modified to act as foaminess- reducer in fluidized bed hydro conversion reactors.

Method for improving ripple reduction during phase shedding in multiphase buck converters for SCADA systems

In the current digital environment, central processing unit (CPUs), field programmable gate array (FPGAs), application-specific integrated circuit (ASICs), as well as peripherals, are growing progressively complex. On motherboards in many areas of computing, from laptops and tablets to servers and Ethernet switches, multiphase phase buck regulators are seen to be more common nowadays, because of the higher power requirements. This study describes a four-stage buck converter with a phase shedding scheme that can be used to power processors in programmable logic controller (PLCs). The proposed power supply is designed to generate a regulated voltage with minimal ripple. Because of the suggested phase shedding method, this power supply also offers better light load efficiency. For this objective, a multiphase system with phase shedding is modeled in MATLAB SIMULINK, and the findings are validated.

Numerical Studies of Disperse Three-Phase Fluid Flows

The dynamics of a three-phase gas–liquid–liquid multiphase system is examined by direct numerical simulations. The system consists of a continuous liquid phase, buoyant gas bubbles, and smaller heavy drops that fall relative to the continuous liquid. The computational domain is fully periodic, and a force equal to the weight of the mixture is added to keep it in place. The governing parameters are selected so that the terminal Reynolds numbers of the bubbles and the drops are moderate; while the effect of bubble deformability is examined by changing its surface tension, the surface tension for the drops is sufficiently high so they do not deform. One bubble in a “unit cell” and eight freely interacting bubbles are examined. The dependency of the slip velocities, the velocity fluctuations, and the distribution of the dispersed phases on the volume fraction of each phase are examined. It is found that while the distribution of drops around a single bubble in a “unit cell” is uneven and depends on its deformability, the distribution of drops around freely interacting bubbles is relatively uniform for the parameters examined in this study.

Molecular dynamics simulation of waxy deposition in crude oil system

Understanding the phase transition and deposition behavior of crude oil system with waxy is of great significance to ensure the safe production and transportation of oil. In this paper, molecular dynamics simulation is employed to explore the deposition process of crude oil system with heterogeneous waxy on the solid surface. The results show that in a multiphase system, the morphology of paraffin wax crystals will change correspondingly at different system temperatures. At low-temperature, the paraffin molecules are arranged in an orderly manner, which are easier to form wax crystals, resulting in the density of the system that changes greatly. As the temperature increases, the aggregation of the wax molecules decreases, which makes the fluidity increase, and it is not easy to form wax crystals.

A mathematical investigation into the uptake kinetics of nanoparticles in vitro

Nanoparticles have the potential to increase the efficacy of anticancer drugs whilst reducing off-target side effects. However, there remain uncertainties regarding the cellular uptake kinetics of nanoparticles which could have implications for nanoparticle design and delivery. Polymersomes are nanoparticle candidates for cancer therapy which encapsulate chemotherapy drugs. Here we develop a mathematical model to simulate the uptake of polymersomes via endocytosis, a process by which polymersomes bind to the cell surface before becoming internalised by the cell where they then break down, releasing their contents which could include chemotherapy drugs. We focus on two in vitro configurations relevant to the testing and development of cancer therapies: a well-mixed culture model and a tumour spheroid setup. Our mathematical model of the well-mixed culture model comprises a set of coupled ordinary differential equations for the unbound and bound polymersomes and associated binding dynamics. Using a singular perturbation analysis we identify an optimal number of ligands on the polymersome surface which maximises internalised polymersomes and thus intracellular chemotherapy drug concentration. In our mathematical model of the spheroid, a multiphase system of partial differential equations is developed to describe the spatial and temporal distribution of bound and unbound polymersomes via advection and diffusion, alongside oxygen, tumour growth, cell proliferation and viability. Consistent with experimental observations, the model predicts the evolution of oxygen gradients leading to a necrotic core. We investigate the impact of two different internalisation functions on spheroid growth, a constant and a bond dependent function. It was found that the constant function yields faster uptake and therefore chemotherapy delivery. We also show how various parameters, such as spheroid permeability, lead to travelling wave or steady-state solutions.