Influence of 2,2,6,6-tetramethylpiperidine and of 2,2,6,6-tetramethylpiperidine-N-oxide on radically induced styrene polymerization

Summary The influence of 2, 2, 6, 6-tetramethylpiperidine TMP and the corresponding N-oxide TEMPO on the kinetics of the radical polymerization of styrene in bulk is described. Results reveal that the piperidine TMP acts as a chain transfer agent with c_tr=0.014 whereas TEMPO is a strong polymerization inhibitor. TEMPO is formed from TMP during polymerization in air saturated styrene.     

Study on low pressure evaporation of fresh water generation system model

A low pressure evaporation fresh water generation system is designed for converting brackish water or seawater into fresh water by distillation in low pressure and temperature. Distillation through evaporation of feed water and subsequent vapor condensation as evaporation produced fresh water were studied; tap water was employed as feed water. The system uses the ejector as a vacuum creator of the evaporator, which is one of the most important parts in the distillation process. Hence liquid can be evaporated at a lower temperature than at normal or atmospheric conditions. Various operating conditions, i.e. temperature of feed water and different orifice diameters, were applied in the experiment to investigate the characteristics of the system. It was found that these parameters have a significant effect on the performance of fresh water generation systems with low pressure evaporation.     

Expected security cost‐based FACTS device allocation using hybrid PSO

This paper presents FACTS device allocation for market‐based power systems. The purpose of the FACTS installation is to provide benefit for all entities. Therefore, we use a concept of minimizing expected security cost (ESC), implying to maximize social welfare, to minimize operating reserve, and to minimize load interruption in annual basis. The FACTS device investment cost is also taken into account. The ESC considers operating cost under normal state and contingencies along with their associated probabilities to occur. Annual basis bid data is used to compute ESC as well as the cost data for load interruption and reserve procurement. This paper also considers control actions among multiple FACTS device to achieve minimum ESC. To solve the overall problem, particle swarm optimization is utilized to obtain optimal FACTS device allocation as main problem while sequential quadratic programing is used to solve optimal power flow as suboptimization problem. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Functional and Well‐Defined β‐Sheet‐Assembled Porous Spherical Shells by Surface‐Guided Peptide Formation

Polypeptides have attracted widespread attention as building blocks for complex materials due to their ability to form higher‐ordered structures such as β‐sheets. However, the ability to precisely control the formation of well‐defined β‐sheet‐assembled materials remains challenging as β‐sheet formation tends to lead to ill‐defined and unprocessable aggregates. This work reports a simple, rapid, and robust strategy to form well‐defined peptide β‐sheet‐assembled shells (i.e., hollow spheres) by employing surface‐initiated N‐carboxyanhydride ring‐opening polymerization under a highly efficient surface‐driven approach. The concept is demonstrated by the preparation of enzyme‐degradable rigid shell architectures composed of H‐bonded poly(L‐valine) (PVal) grafts with porous and sponge‐like surface morphology. The porous PVal‐shells exhibit a remarkable and unprecedented ability to non‐covalently entrap metal nanoparticles, proteins, drug molecules, and biorelevant polymers, which could potentially lead to a diverse range of biodegradable and functional platforms for applications ranging from therapeutic delivery to organic catalysis.     

A tree-based stacking ensemble technique with feature selection for network intrusion detection

Applied Intelligence - Several studies have used machine learning algorithms to develop intrusion systems (IDS), which differentiate anomalous behaviours from the normal activities of network...     

Retention of austenite in the welded microstructure of a 0.16C–1.6Mn–1.5Si (wt.%) TRIP steel

In this work, the retention of austenite in post-welded microstructures of a 0.16C–1.6Mn–1.5Si (wt.%) TRIP steel is investigated. Fully penetrated welds are produced by means of gas tungsten arc (GTA) welding and laser beam (LB) welding. The microstructure, particularly retained austenite, is analyzed using optical microscopy, Vickers hardness measurements, X-ray diffraction and saturation magnetization. It is found that the GTA welded TRIP steel contains a relatively large fraction of retained austenite, which may benefit the weldability of this steel. A minimum hardness is found in the heat-affected zone (HAZ) next to a high hardness plateau after both LB and GTA welding as a result of a large fraction of ferrite. It is suggested that for TRIP steels, proper control of the formation and decomposition of retained austenite in the HAZ is important to prevent weld failure. The hardness is therefore not a sufficient indicator for the weldability.     

Development of renewable resource–based cellulose acetate bioplastic: Effect of process engineering on the performance of cellulosic plastics

This paper deals with the development of a cellulose acetate biopolymer. Plasticization of this biopolymer under varying processing conditions to make it a suitable matrix polymer for bio‐composite applications was studied. In particular, cellulose acetate was plasticized with varying concentrations of an eco‐friendly triethyl citrate (TEC) plasticizer, unlike a conventional, petroleum‐derived phthalate plasticizer. Three types of processing were used to fabricate plasticized cellulose acetate parts: compression molding, extrusion followed by compression molding, and extrusion followed by injection molding. The processing mode affected the physicomechanical and thermal properties of the cellulosic plastic. Compression molded samples exhibited the highest impact strength, tending towards the impact strength of a thermoplastic olefin (TPO), while samples that were extruded and then injection molded exhibited the highest tensile strength and modulus values. Increasing the plasticizer content in the cellulosic plastic formulation improved the impact strength and strain to failure while decreasing the tensile strength and modulus values. The coefficient of thermal expansion (CTE) of the cellulose acetate increased with increasing amounts of plasticizer. Plasticized cellulose acetate was found to be processable at 170–180°C, approximately 50°C below the melting point of neat cellulose acetate.     

Detection of Fe3O4/PEG nanoparticles using one and two spin-valve GMR sensing elements in wheatstone bridge circuit

Journal of Materials Science: Materials in Electronics - Simple Wheatstone bridge-giant magnetoresistance (GMR) sensors with one and two spin-valve (SV) thin films were developed for detecting...