pH- and thermo-sensitive MTX-loaded magnetic nanocomposites: synthesis,characterization, and in vitro studies on A549 lung cancer cell and MR imaging

In the current study, we proposed a facile method for fabrication of multifunctional pH- and thermo-sensitive magnetic nanocomposites (MNCs) as a theranostic agent for using in targeted drug delivery and magnetic resonance imaging (MRI). To this end, we decorated Fe₃O₄ magnetic nanoparticles (MNPs) with N,N-dimethylaminoethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm), best known for their pH- and thermo-sensitive properties, respectively. We also conjugated mesoporous silica nanoparticles (MSNs) to polymer matrix acting as drug container to enhance the drug encapsulation efficacy. Methotroxate (MTX) as a model drug was successfully loaded in MNCs (M-MNCs) via surface adsorption onto MSNs and electrostatic interaction between drug and carrier. The pH- and temperature-triggered release of MTX was concluded through the evaluation of in vitro release at both physiological and simulated tumor tissue conditions. Based on in vitro cytotoxicity assay results, M-MNCs significantly revealed higher antitumor activity compared to free MTX. In vitro MR susceptibility experiment showed that M-MNCs relatively possessed high transverse relaxivity (r₂) of about 0.15?mM^?1·ms^?1 and a linear relationship between the transverse relaxation rate (R₂) and the Fe concentration in the M-MNCs was also demonstrated. Therefore, the designed MNCs can potentially become smart drug carrier, while they also can be promising MRI negative contrast agent.     

Preparation of cupric palmitate membrane,its characterization and evaluation of thermodynamically effective fixed charge density

Membrane potentials have been measured across, parchment-supported cupric palmitate membrane separating various 1∶1 electrolytes at concentrations C₁ and C₂ such that C₂=10 C₁. Membrane potential data have been used to calculate transference number of ions, permselectivity and also to derive the thermodynamically effective fixed charge density which is an important characteristic governing the membrane phenomena, by utilizing the generally accepted and most widely used theory of Teorell-Meyer and Sievers as well as the recent theories for membrane potential of Kobatake et al. and Nagasawa et al. based on the principles of nonequilibrium thermodynamics. The values of charge densities derived from different theories were almost the same, confirming thereby the validity of the recently developed theories of membrane potential.     

Development of an efficient stabiliser mixture for physical stability of nonfat unfizzy doogh

The effects of locust bean, carboxymethyl cellulose, a mixture of locust bean and carboxymethyl cellulose and Persian gum on different properties of nonfat doogh were studied over a period of 28 days. The results showed that samples containing a mixture of locust bean and carboxymethyl cellulose had the highest stability. Furthermore, the rheological behaviour of the doogh changed from Newtonian to pseudoplastic. Better sensory acceptability was shown for the treatments containing a mixture of locust bean gum and carboxymethyl cellulose. In general, it was shown that a mixture of locust bean and carboxymethyl cellulose could be of practical use in the industrial production of nonfat doogh.     

Mixed convective heat transfer enhancement in a ventilated cavity by flow modulation via rotating plate

The present study numerically explores the mixed convection phenomena in a differentially heated ventilated square cavity with active flow modulation via a rotating plate. Forced convection flow in the cavity is attained by maintaining external fluid flow through an opening at the bottom of the left cavity wall while leaving it through another opening at the right cavity wall. A counter-clockwise rotating plate at the center of the cavity acts as an active flow modulator. Moving mesh approach is used for the rotation of the plate and the numerical solution is achieved using arbitrary Lagrangian-Eulerian finite element formulation with a quadrilateral discretization scheme. Transient parametric simulations have been performed for various frequency of the rotating plate for a fixed Reynolds number (Re) of 100 based on maximum inlet flow velocity while the Richardson number (Ri) is maintained at unity. Heat transfer performance has been evaluated in terms of spatially averaged Nusselt number and time-averaged Nusselt number along the heated wall. Power spectrum analysis in the frequency domain obtained from the fast Fourier transform analysis indicates that thermal frequency and plate frequency start to deviate from each other at higher values of velocity ratio (>4).     

Model for boiling explosion during rapid liquid heating

The process of rapid liquid heating with a linearly increasing boundary temperature condition has been simulated by applying the analytical solution of 1D semi-infinite heat conduction in association with the molecular theory of homogeneous nucleation boiling. A control volume having the size of a characteristic critical cluster at the liquid boundary is considered, and the corresponding energy balance equation is obtained by considering two parallel competing processes that take place inside the control volume, namely, transient external energy deposition and internal energy consumption due to bubble nucleation and subsequent growth. Depending on the instantaneous rate of external energy deposition and boiling heat consumption within the control volume, a particular state is defined as the boiling explosion condition in which bubble generation and growth cause the liquid sensible energy to decrease. The obtained results are presented in terms of the average liquid temperature rise within the control volume, maximum attainable liquid temperature before boiling explosion and the time required to achieve the condition of boiling explosion. The model is applied for the case of water heating at atmospheric pressure with initial and boundary conditions identical to those reported in the literature. Model predictions concerning boiling explosion are found to be in good agreement with the experimental observations. The boiling explosion condition as predicted by the present model is verified by comparing the heat flux across the liquid–vapor interface with the corresponding limit of maximum possible heat flux, q_max,max, at the time of boiling explosion. A comparative study between the actual heat flux and the limit of maximum heat flux, q_max,max, at the time of boiling explosion for different rates of boundary heating indicates that, with much higher boundary heating rates, it is possible to heat the liquid to a much higher temperature before theoretical instantaneous boiling explosion occurs.     

Studies with inorganic precipitate membrane: evolution of thermodynamically effective fixed charge density and test of the most recently developed theory of membrane potential based on the principles of non-equilibrium thermodynamics

Electrical potentials developed across nickel, manganese chromate and cupric iodide membranes using various 1:1 electrolytes are reported. Thermodynamically effective fixed charge density, which is an important parameter governing the membrane phenomena, has been evaluated by the recently developed theory of Nagasawa et al. Most recently developed theories of Toyoshima and Nozaki based on the principles of the irreversible thermodynamics has been examined to predict the bi-ionic potentials developed across the membranes. Theoretical predictions were borne out quite satisfactorily by our experimental results.     

CWIPL II,a mechanism for improving throughput and lead time in unbalanced flow line

Critical WIP loops II (CWIPL II) is a proposed material flow control mechanism for an unbalanced flow line environment. CWIPL II is based on CWIPL and it determines critical loops in unbalanced lines. The WIP of critical loops identifies the time of releasing raw material to the line. CWIPL II proposed a new classification for unbalanced flow line which is ‘near unbalanced flow line’ and ‘perfect unbalanced flow line’. In near unbalanced line, there is one bottleneck and a raw material release to the line if ‘WIP of the bottleneck’ or ‘WIP upstream the bottleneck’ is less than defined level. In perfect unbalanced line there are multiple bottleneck and a raw material release to the line if ‘WIP upstream the slowest machine’ or ‘WIP between two primary bottleneck’ is less than defined level. Like CWIPL, the necessary condition for releasing the raw material is ‘idleness of the first machine’. CWIPL II is compared with CONWIP and TOC by simulation. Different scenarios are employed in the comparison analysis. The scenarios address variables such as number of machines, processing time distribution, WIP target level. Location of slowest machine and location of two primary bottlenecks are considered in examples. Simulation results and statistical tests of 141 numerical examples show that CWIPL II improves lead time in near unbalanced line and throughput in perfect unbalanced line compared with TOC. Because of the trade off between line throughput and lead time, the mechanism that improves one of them while maintaining the other at previous level is valuable. It is shown that CWIPL II has improved TOC in the cases that TOC hasn’t improved CONWIP.     

A pressure output feedback control of turbo compressor surge with a thrust magnetic bearing actuator

This paper presents a pressure output feedback control of turbo compressor surge using tip clearance actuation with a thrust magnetic bearing actuator. First, static and dynamic compressor models were obtained for a commercial turbocharger, and the surge point was found through local stability analysis. Then, the effect of tip clearance on the compressor pressure rise was derived, and Lyapunov analysis was used to establish a limit of stability with tip clearance modulation. After that, a linear quadratic (LQ) state feedback control was designed considering the limit established by the Lyapunov analysis. In addition, an extended Kalman filter (EKF) was designed to estimate the mass flow rate from the measured compressor pressure. Finally, the pressure output feedback controller was built by combining the LQ state feedback control and EKF. Control simulation proved the effectiveness of the output feedback controller. This paper was recommended for publication in revised form by Associate Editor Dong Hwan Kim Dr. Ahn earned Ph.D. from Seoul National University in 2001. He was a research associate of University of Virginia. He is currently an assistant professor of department of mechanical engineering at Soongsil University and serving as an editor of international journal of rotating machinery. His research interests are rotordynamics, control and mechatronics. Mr. Park is a junior research engineer in Doosan infracore. He received his master from Seoul National University. His research area is on dynamics and control of rotating machinery. Dr. Sanadgol is an assistant Professor of Physics and Engineering at Sweet Briar College. She earned her PhD in Mechanical and Aerospace Engineering with a focus in controls from the University of Virginia in 2006. Her research interests are in controlling flow instabilities in compressors and application of nonlinear control theories to mechatronics systems. Dr. Park received his PhD degree from the Seoul National University, Korea in 2007. He is currently director of research institute at KMB&SENSOR company. His research interests include the precision machine design, rotor dynamics, and magnetic actuators. Dr. Han received the Dipl.-Ing. and Dr.-Ing. in mechanical engineering from University of Karsruhe, Germany in 1975 and 1979, respectively. In 1982, he joined the school of mechanical and aerospace engineering, Seoul National University as an assistant professor. He is currently an honorary professor of mechanical engineering. His research interests are in machine element design, magnetic bearing, lubrication engineering and Bio-MEMS devices. Dr. Maslen is a Professor of Mechanical and Aerospace Engineering at the University of Virginia. He earned his Bachelor of Science in 1980 from Cornell University and his doctorate from the University of Virginia in 1991. His research focuses on application of automatic controls to electromechanical systems with a concentration in magnetic bearings.     

Development of electrically conductive hybrid nanofibers based on CNT‐polyurethane nanocomposite for cardiac tissue engineering

Conductive nanofibers have been considered as one of the most interesting and promising candidate scaffolds for cardiac patch applications with capability to improve cell–cell communication. Here, we successfully fabricated electroconductive nanofibrous patches by simultaneous electrospray of multiwalled carbon nanotubes (MWCNTs) on polyurethane nanofibers. A series of CNT/PU nanocomposites with different weight ratios (2:10, 3:10, and 6:10wt%) were obtained. Scanning electron microscopy, conductivity analysis, water contact angle measurements, and tensile tests were used to characterize the scaffolds. FESEM showed that CNTs were adhered on PU nanofibers and created an interconnected web‐like structures. The SEM images also revealed that the diameters of nanofibers were decreased by increasing CNTs. The electrical conductivity, tensile strength, Young's modulus, and hydrophilicity of CNT/PU nanocomposites also enhanced after adding CNTs. The scaffolds revealed suitable cytocompatibility for H9c2 cells and human umbilical vein endothelial cells (HUVECs). This study indicated that simultaneous electrospinning and electrospray can be used to fabricate conductive CNT/PUnanofibers, resulting in better cytocompatibility and improved interactions between the scaffold and cardiomyoblasts.