Effects of halloysite nanotubes and kaolin loading on the tensile,swelling, and oxidative degradation properties of poly(vinyl alcohol)/chitosan blends

[Halloysite nanotubes (HNT)]‐filled and kaolin filled composite films based on poly(vinyl alcohol) (PVA)/chitosan (CS) blend were prepared via solution casting method. Tensile properties, fracture morphology, FTIR spectra, thermal stability, swelling properties, moisture absorption, and oxidative degradation of the composite films were investigated. Addition of 0.5 wt% of filler led to the optimum tensile properties of the films. Increased roughness and tearing in the fracture surface morphology supported the tensile results. The FTIR results indicated there were physical interactions present in the composite films. Thermal stability of the composite films differed slightly where PVA/CS/HNT composite films showed better thermal stability than PVA/CS/kaolin composite films. Moreover, the presence of HNT and kaolin fillers in the blend reduced the swelling and moisture absorption properties of the films. Finally, the composite films were degraded by using Fenton's reagent. Degradation percentage of the composite films decreased with increasing filler loading. J. VINYL ADDIT. TECHNOL., 19:55–64, 2013. © 2013 Society of Plastics Engineers     

Monodisperse Gold Nanoparticles: A Review on Synthesis and Their Application in Modern Medicine

Gold nanoparticles (AuNPs) are becoming increasingly popular as drug carriers due to their unique properties such as size tenability, multivalency, low toxicity and biocompatibility. AuNPs have physical features that distinguish them from bulk materials, small molecules and other nanoscale particles. Their unique combination of characteristics is just now being fully realized in various biomedical applications. In this review, we focus on the research accomplishments and new opportunities in this field, and we describe the rising developments in the use of monodisperse AuNPs for diagnostic and therapeutic applications. This study addresses the key principles and the most recent published data, focusing on monodisperse AuNP synthesis, surface modifications, and future theranostic applications. Moving forward, we also consider the possible development of functionalized monodisperse AuNPs for theranostic applications based on these efforts. We anticipate that as research advances, flexible AuNPs will become a crucial platform for medical applications.     

Control of polystyrene batch reactors using neural network based model predictive control (NNMPC): An experimental investigation

Controlling batch polymerization reactors imposes great operational difficulties due to the complex reaction kinetics, inherent process nonlinearities and the continuous demand for running these reactors at varying operating conditions needed to produce different polymer grades. Model predictive control (MPC) has become the leading technology of advanced nonlinear control adopted for such chemical process industries. The usual practice for operating polymerization reactors is to optimize the reactor temperature profile since the end use properties of the product polymer depend highly on temperature. This is because the end use properties of the product polymer depend highly on temperature. The reactor is then run to track the optimized temperature set-point profile. In this work, a neural network-model predictive control (NN-MPC) algorithm was implemented to control the temperature of a polystyrene (PS) batch reactors and the controller set-point tracking and load rejection performance was investigated. In this approach, a neural network model is trained to predict the future process response over the specified horizon. The predictions are passed to a numerical optimization routine which attempts to minimize a specified cost function to calculate a suitable control signal at each sample instant. The performance results of the NN-MPC were compared with a conventional PID controller. Based on the experimental results, it is concluded that the NN-MPC performance is superior to the conventional PID controller especially during process startup. The NN-MPC resulted in smoother controller moves and less variability.     

Melt compounded polylactic acid-hexagonal boron nitride-aluminum oxide hybrid composites for electronic applications: impact of hybrid fillers on thermophysical,dielectric, optical,and hardness properties

ABSTRACT

The dielectric, thermophysical, optical, and hardness of pure polylactic acid (PLA) and hBN micropowder and Al₂O₃ nanopowder (1% to 30%) reinforced PLA hybrid composites were investigated. Hybrid composites exhibit improved thermal conductivity (k – 0.54 W/mK), permittivity (?? – 4.6720 @ 1 MHz to 1 GHz) with very low loss tangent (tan δ < 0.02). High absorption in UV region was observed for all hybrid composites. Overall, the prepared hybrid composites can be used as a bio-based dielectric substrates, enclosures, thermal interface material for low temperature applications and UV-absorbable coating materials for fabric, packaging, and storage applications.     

SIMULATED ANNEALING TO ESTIMATE THE OPTIMAL CUTTING CONDITIONS FOR MINIMIZING SURFACE ROUGHNESS IN END MILLING Ti-6Al-4V

This study presents the estimation of the optimal effect of the radial rake angle of the tool, combined with cutting speed and feed in influencing the surface roughness result. Studies on optimization of cutting conditions for surface roughness in end milling involving radial rake angle are still lacking. Therefore, considering the radial rake angle, this study applied simulated annealing in determining the solution of the cutting conditions to obtain the minimum surface roughness when end milling Ti-6Al-4V. Considering a set of experimental machining data, the regression model is developed. The best regression model was considered to formulate the fitness function of the simulated annealing. It was recommended that the cutting conditions should be set at highest cutting speed, lowest feed and highest radial rake angle in order to achieve the minimum surface roughness of 0.1385 µm. Subsequently, it was found that by using simulated annealing, the minimum surface roughness was much lower than the experimental sample data, regression modelling and response surface methodology technique by about 27%, 26% and 50%, respectively.     

SIMULATION AND EXPERIMENTAL IMPLEMENTATION OF A NEURAL-NETWORK-BASED INTERNAL-MODEL CONTROL STRATEGY ON A REACTOR SYSTEM

The use of inverse-model-based control strategy for nonlinear system has been increasing lately. However it is hampered by the difficulty in obtaining the inverse of nonlinear systems analytically. Since neural networks has the ability to model such inverses, it has become a viable alternative. Although many simulations using neural network inverse models For controls have been reported recently, no actual experimental application has been reported on a reactor system. In this paper we describe a novel experimental application of a neural network inverse-model based control method on a partially simulated pilot plant reactor, exhibiting steady state parametric sensitivity and designed to test the use of such nonlinear algorithms. The implementation involved the control of the reactor temperature under set point changes, disturbance rejection and set point regulation with plant/model mismatches. Simulation tests on the model of the system were also carried out to enable better design of the neural network models and to highlight the differences between simulation and actual online results. The online implementation results obtained were sufficient to demonstrate the capability of applying these neural-network-based control methods in real systems.     

Survival of freeze-dried microcapsules of α-galactosidase producing probiotics in a soy bar matrix

Soy oligosaccharides, mainly α-galactosides, are prevalently present in soy protein products, and can result in unfavorable digestive effects when consumed. The aim of this research was to investigate the efficiency of α-galactoside reduction by probiotic bacterial hydrolysis and if such bacteria could be maintained in a high number in a soy protein product in a microencapsulated and freeze-dried form. The probiotic bacterium, Lactobacillus acidophilus LA-2, when induced by raffinose, exhibited a high level of α-galactosidase activity at 5.0 U/mg. To preserve probiotics with high viability, cells were microencapsulated and freeze-dried. Optimization of microencapsulation presented that a combination of κ-carrageenan and inulin at a proportion of 1.9:0.1 (w:w) as capsule wall materials, significantly retained the viability of the probiotics through freeze-drying (P ≤ 0.05). Scanning electron microscopic images confirmed that the morphology of the microcapsules was well preserved after freeze-drying. Upon incorporation into soy protein bars, the freeze-dried microcapsules of L. acidophilus LA-2 remained in high numbers throughout 14 weeks of storage at 4 °C. Results of this work with the support of other studies on microencapsulation benefits indicate a promising use of freeze-dried α-galactosidase positive microencapsulated probiotics in a soy food.     

SiN/bamboo like carbon nanotube composite electrodes for lithium ion rechargeable batteries

A dual stage technique employing hot filament chemical vapor deposition (HFCVD) and radio frequency sputtering was used to synthesize SiN/BCNTs (bamboo like carbon nanotubes) on copper substrates. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Electron field emission studies (EFE), charge-discharge, and cyclic voltammetry. The comprehensive characterization is consistent with a nanolayer of amorphous SiN on BCNTs. Field emission experiments confirm the excellent contact of the SiN nanolayer with the surface of the BCNTs necessary for fabrication of a coin cell. Electrochemical testing shows that SiN/BCNT electrode can deliver an initial discharge capacity of 2000 mAh g⁻¹ which is higher than the capacity of graphite and the reversible capacity after ten cycles is 300 mAh g⁻¹. The cyclic voltammetry results suggest good reversibility with Li during cycling.