Nanocomposites from Polycaprolactone (PCL)/Soy Protein Isolate (SPI) Blend with Organoclay

New biobased, ecofriendly nanocomposites were prepared from polycaprolactone (PCL)/soy protein isolate (SPI) blend (80/20 wt/wt) with organically modified clay, by melt compounding. X-ray diffraction and transmission electron microscopy analysis revealed that an intercalated nanocomposite was formed and the silicate layers of the clay were uniformly dispersed at a nanometer scale in matrix polymer. There was great enhancement of both tensile and dynamic mechanical properties in the nanocomposite. A rheological study revealed that the nanocomposite exhibits strong shear-thinning behavior in the melted state, and a percolated network of clay particles was formed in the melted state.     

Graft copolymerization with new class of acidic peroxo salts as initiators. I. Grafting of acrylamide onto cotton–cellulose using potassium monopersulfate,catalyzed by co(II)

Graft copolymerization of acrylamide (AM) onto cotton–cellulose has been studied using a new class of acidic peroxo-salt “potassium monopersulfate” as initiator catalyzed by Co(II). It is observed that the graft yield is influenced by the reaction time, temperature, and concentrations of the monomer, catalyst, initiator, at fixed weight of the polymer. Maximum graft yield (30.8%) is obtained at 40°C under nitrogen atmosphere for the concentrations of monomer 1.2M; initiator 4.83 × 10^?3M; Co(II) 5 × 10^?4M for 4 h of reaction time. The graft copolymers after proper purification have been subjected to IR analysis, testing of their water-retention properties, rot resistance, tensile properties, and behavior towards acids and alkalies. The results of such analysis are compared with the base. Suitable mechanism for the graft copolymerization is suggested and grafting rate has been evaluated.     

Development of a biodegradable rice straw‐g‐poly(methyl methacrylate)/sodium silicate composite flame retardant

Natural fiber composites have been prepared by grafting hydrophobic monomer methyl methacrylate (MMA) onto chemically modified rice straw (RS) using complex initiating system [CuSO₄/glycine/ammonium persulfate (APS)] in an aqueous medium with and without the additive, sodium silicate (SS). The chemically modified RS, RS‐g‐PMMA, and RS‐g‐PMMA/SS composite have been characterized by FT‐IR, and their morphology was studied by scanning electron microscopy (SEM). The thermal behavior and tensile properties of the samples have been studied, and the flame retardant properties have also been evaluated by limiting oxygen index (LOI) test and cone calorimetry. The biodegradation and water absorbency have been carried out for its ecofriendly nature and better commercialization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies of microstructural,dielectric, and impedance spectroscopic properties of Bi0.617Y0.05Cu3Ti4O12 ceramic synthesized through semi-wet route

Bi_0.617Y_0.05Cu₃Ti₄O₁₂(BYCTO) was successfully synthesized through an economically semi-wet route using metals nitrates, acetate, and TiO₂ precursor and sintered at 1173 K for 8 h. The single phase of ceramic was authorized by XRD analysis. The crystallite size of BYCTO ceramic was calculated to be 62.3 nm through XRD measurement. The particle size obtained by TEM analysis was to be in the range of 55?±?7 nm. The average grain size observed through the SEM technique was 0.783 μm. The route means square roughness, as well as average roughness, were determined to be 0.224 μm and 0.179 μm by atomic force microscope. The dielectric constant (?′) of BYCTO was measured to be 1481 at 307 K and 100 Hz. The tangent loss (tan δ) was observed to be in the range of 0.13–0.29 at all selected temperatures (307–487 K) and 10 kHz which is lower than that of Bi_2/3Cu₃Ti₄O₁₂. The oxidation state of all metal present in the ceramic material was verified by XPS analysis.

     

An efficient fast algorithm for discovering closed+ high utility itemsets

In recent years, high utility itemsets (HUIs) mining from the transactional databases becomes one of the most emerging research topic in the field of data mining due to its wide range of applications in online e-commerce data analysis, identifying interesting patterns in biomedical data and for cross marketing solutions in retail business. It aims to discover the itemsets with high utilities efficiently by considering item quantities in a transaction and profit values of each item. However, it produces a tremendous number of HUIs, which imposes further burden in analysis of the extracted patterns and also degrades the performance of mining methods. Mining the set of closed ⁺ high utility itemsets (CHUIs) solves this issue as it is a loss-less and condensed representation of all HUIs. In this paper, we aim to present a new algorithm for finding CHUIs from a transactional database, called the CHUM (Closed ⁺ High Utility itemset Miner), which is scalable and efficient. The proposed mining algorithm adopts a tricky aimed vertical representation of the database in order to speed up the execution time in generating itemset closures and compute their utility information without accessing the database. The proposed method makes use of the item co-occurrences strategy in order to further reduce the number of intersections needed to be performed. Several experiments are conducted on various sparse and dense datasets and the simulation results clearly show the scalability and superior performance of our algorithm as compared to those for the existing state-of-the-art CHUD (Closed ⁺ High Utility itemset Discovery) algorithm.     

Correlation of atomic force–distance microscopy and spectrophotometric techniques in the analysis of optical multilayer spectral aging process

Aging-related multilayer spectral instabilities can pose severe performance limiting constraints to optical multilayer devices. In this study such instabilities of some periodic Gd₂O₃/SiO₂ optical multilayer systems have been explored using scanning probe force–distance microscopy and spectrophotometric techniques. In the present case, a strong correlation between the spectral instabilities and the viscoelastic properties of the associated thin film layers has been distinctly noticed. From the experimental analysis it was quite evident that the spectral instability, which starts during the nucleation and growth stage in thin films, continues to persist at a much longer time scale following aging processes. In this study it is shown that the elastic properties of the constituent thin films, the layer design and the bilayer thickness have established a strong interrelation which ultimately contributes to the multilayer instabilities. These spectral instabilities also have strong interconnections with the morphological and viscoelastic changes in such multilayers. Other multilayer parameters like the total number of layers, the layer structure, the microroughness evolutions, related stiffness factors and the adhesion properties of the periodic layer systems contribute substantially to this instability process.     

Trends in partial discharge pattern classification: a survey

Partial discharge (PD) detection, measurement and classification constitute an important tool for quality assessment of insulation systems utilized in HV power apparatus and cables. The patterns obtained with PD detectors contain characteristic features of the source/class of the respective partial discharge process involved. The recognition of the source from the data represents the classification stage. Usually, this stage consists of a two-step procedure, i.e., extraction of feature vector from the data followed by classification/recognition of the corresponding source. The various techniques available for achieving the foregoing task are examined and analyzed; while limited success has been achieved in the identification of simple PD sources, recognition and classification of complex PD patterns associated with practical insulating systems continue to pose appreciable difficulty.     

Rendezvous in space with minimal sensing and coarse actuation

In this paper, we propose a control law to achieve a rendezvous of autonomous vehicles moving in three-dimensional (3D) space, using minimal data sensing and quantized control. A pre-assigned graph uniquely assigns the pursuer-target pair in a cyclic manner. A quantized control law has been proposed which allows the vehicle to pitch and yaw simultaneously in the required direction and track its target agent. The only measurement required for the proposed control law is the quadrant from which the target vehicle moves out of the field-of-view of the pursuing vehicle. A Lyapunov function is chosen to find a domain for the field-of-view which guarantees rendezvous under the proposed control law. Computer simulations are presented to demonstrate the control law.     

Mechanical Properties and Nanocrystallization Behavior of Al-Ni-La Alloys

Rapidly solidified Al₈₉Ni₆La₅ ribbons were obtained by induction melting and ejecting the melt onto a rotating Cu wheel in an Ar atmosphere. The ribbons were investigated by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), transmission electron microscopy (TEM), microindentation, and nanoindentation techniques. The XRD and TEM studies revealed that the ribbon was fully amorphous; however, DSC did not show any glass transition. The alloy undergoes two stages of crystallization. The growth of fcc-Al is responsible for the first stage, and precipitation of Al₃Ni and Al₁₁La₃ is responsible for the second stage of crystallization. Microhardness of ribbons in the as-melt-spun, partially, and fully devitrified conditions was examined and subsequently correlated with evolved microstructure. Significant improvement in hardness was observed, with the progress of primary nanocrystallization, due to the effective barrier to shear band by a hard La-rich shell around the fcc-Al nanocrystals and enrichment of the remaining amorphous matrix by the solute elements. The pile up of materials in the form of semicircular shear bands was observed around all the indentations. During nanoindentation, it was observed that hardness and modulus values were initially increased and then decreased. The reasons for such observation were also discussed.