Assessment of a fuzzy logic based MRAS observer used in a photovoltaic array supplied AC drive

In this paper a fuzzy logic (FL) based model reference adaptive system (MRAS) speed observer for high performance AC drives is proposed. The error vector computation is made based on the rotor-flux derived from the reference and the adaptive model of the induction motor. The error signal is processed in the proposed fuzzy logic controller (FLC) for speed adaptation. The drive employs an indirect vector control scheme for achieving a good closed loop speed control. For powering the drive system, a standalone photovoltaic (PV) energy source is used. To extract the maximum power from the PV source, a constant voltage controller (CVC) is also proposed. The complete drive system is modeled in MATLAB/Simulink and the performance is analyzed for different operating conditions.     

Position-specific chemical modification and quantitative proteomics disclose protein orientation adsorbed on silica nanoparticles

We describe a method for determining the orientation of cytochrome c, RNase A, and lysozyme on silica nanoparticles (SNPs) using chemical modification combined with proteolysis-mass spectrometry. The proteins interacted with SNPs through preferential adsorption sites, which are dependent on SNP diameter; 4 nm SNPs induce greater structural stabilization than 15 nm particles, presumably due to greater surface curvature of the former. These results suggest that nanoparticle size and protein structure influence protein orientation on SNPs.     

Inhibition of HSV‐1 Attachment,Entry, and Cell‐to‐Cell Spread by Functionalized Multivalent Gold Nanoparticles

The use of modified nanoparticles in interactions with biological targets is attracting rapidly increasing attention. In this Full Paper, the application of gold nanoparticles capped with mercaptoethanesulfonate (Au‐MES NPs) as effective inhibitors of Herpes simplex virus type 1 infection based on their ability to mimic cell‐surface‐receptor heparan sulfate is described. Mechanistic studies reveal that Au‐MES NPs interfere with viral attachment, entry, and cell‐to‐cell spread, thereby preventing subsequent viral infection in a multimodal manner. The ligand multiplicity achieved with carrier nanoparticles is crucial in generating polyvalent interactions with the virus at high specificity, strength, and efficiency. Such multivalent‐nanoparticle‐mediated inhibition is a promising approach for alternative antiviral therapy.     

Crystallographic evaluation of sodium zirconium phosphate as a host structure for immobilization of cesium

Sodium zirconium phosphate (NZP) is a potential material for immobilization of nuclear effluents. The existence of cesium containing NZP structure was determined on the basis of crystal data of solid solution. It was found that up to ~9.0 wt% of cesium could be loaded into NZP formulations without significant changes of the three-dimensional framework structure. The crystal chemistry of Na_1−x Cs _x Zr₂P₃O₁₂ (x = 0.1–0.4) has been investigated using General Structure Analysis System programming. The CsNZP phases crystallize in the space group R-3c and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The unit cell volume and polyhedral (ZrO₆ and PO₄) distortion increase with rise in the mole% of Cs⁺ in the NZP matrix. The PO₄ stretching and bending vibrations in the infrared region have been assigned. SEM, TEM, and EDAX analysis provide analytical evidence of cesium in the matrix.     

Effect of nanoclay on positive temperature coefficient to resistivity characteristics of high density polyethylene/silver‐coated glass bead composites

Positive temperature coefficient to resistivity characteristics of high density polyethylene (HDPE)/silver (Ag)‐coated glass bead (45 wt%) composites, without and with nanoclay, has been investigated with reference to HDPE/carbon black (CB) (10 wt%) composites. Plot of resistivity versus temperature of HDPE/CB (10 wt%) composites showed a sudden rise in resistivity (PTC trip) at ≈128°C, close to the melting temperature (T_m) of HDPE. However, for HDPE/Ag coated glass bead (45 wt%) composites, the PTC trip temperature (≈88°C) appeared well below the T_m of HDPE. Addition of 1 phr clay in the composites resulted in an increase in PTC trip temperature of HDPE/Ag‐coated glass bead (45 wt%) composites, whereas no significant effect of clay on PTC trip temperature was evident in HDPE/CB/clay composites. We proposed that the PTC trip temperature in HDPE/Ag‐coated glass bead composites was governed by the difference in coefficient of thermal expansion of HDPE and Ag‐coated glass beads. The room temperature resistivity and PTC trip temperature of HDPE/Ag‐coated glass bead (45 wt%) composites were found to be very stable on thermal cycling. Dynamic mechanical analyzer results showed higher storage modulus of HDPE/Ag‐coated glass bead (45 wt%) composites compared with the HDPE/CB (10 wt%) composites. Thermal stability of HDPE/Ag‐coated glass bead (45 wt%) composites was also improved compared with that of HDPE/CB (10 wt%) composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Response of growing Japanese quails to dietary concentration of L‐threonine

The influence of dietary levels of L ‐threonine (Thr) on growth and immune response was investigated in growing (0–5 weeks of age) Japanese quails (n = 288). Three dietary treatments were formulated using three levels of Thr [9.6, 10.2 and 11.2 kg^?1 diet dry matter (DM)] at a fixed protein level of 233 g kg^?1 and an energy level of 12.15 MJ (2900 kcal) metabolizable energy (ME) kg^?1 feed dry matter. A metabolism trial with a 3‐day collection period was conducted at the third week of age employing all the birds. The cell‐mediated (using PHA‐P) and humoral (SRBC response) immune responses were measured at the fourth week of age. Carcass traits were assessed at the end of fifth week of age. Body weight gain was lower (P < 0.01) in birds received 9.6 g Thr kg^?1 DM than in groups fed 10.2 g or 11.2 g kg^?1 DM in the diet, but there was no significant difference in gain between the groups fed 10.2 or 11.2 g Thr kg^?1 DM in the diet. Feed intake differed significantly owing to Thr levels being lowest (P < 0.05) at 9.6 g Thr kg^?1 DM in the diet. Feed conversion ratio (FCR), protein efficiency and energy efficiency improved at the 11.2 g kg^?1 level from 0 to 3 weeks of age; however, from 3 to 5 weeks of age, better FCR emanated from a diet with 9.6 g Thr kg^?1 DM. The nitrogen balance did not differ (P > 0.05) with Thr level. Carcass traits, relative weight of immune organs and cell‐mediated (PHA‐P) and humoral (SRBC response) immune responses did not differ significantly (P > 0.05) as a result of the dietary treatments. Copyright © 2006 Society of Chemical Industry     

Sorptive removal of methylene blue from aqueous solutions by polymer/activated charcoal composites

In this study, a new sorbent, a poly(acrylamide‐co‐itaconic acid) [P(AAm‐co‐IA)]/activated charcoal (AC) composite, was prepared by the aqueous polymerization of acrylamide and itaconic acid in the presence of AC with N,N′‐methylene bisacrylamide as a crosslinker and potassium persulfate as an initiator. The P(AAm‐co‐IA)/AC composite sorbent showed a fair capacity to adsorb the cationic dye methylene blue. The maximum sorption capacity, as studied at 23, 37, and 50°C and determined with the Langmuir isotherm model, was found to be 909.0, 312.5, and 192.3 mg/g, respectively. For an initial concentration of 5 mg/L, the kinetic uptake data were studied with various kinetic models. The pseudo‐second‐order equation was found to fairly fit the uptake data with a regression value of 0.999. The dye uptake increased with the pH of the sorbate solution, and the optimum pH was found to be in the range of 7–10. Intraparticle diffusion was also observed to take place, and the coefficient of intraparticle diffusion was evaluated to be 26.51 × 10^?2 mg g^?1 min^?1/2. The various thermodynamic parameters were also determined to predict the nature of the uptake process. The sorption process was found to be spontaneous, as indicated by a negative standard free energy change. The negative standard enthalpy change suggested an exothermic nature for the uptake. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Unveiling the self-assembly behavior of copolymers of AAc and DMAPMA in situ to form smart hydrogels displaying nanogels-within-macrogel hierarchical morphology

Stimulus responsive hydrogels are being considered as one of the most crucial biomaterials of current generation. A new technique has been established for developing hydrogels based on Acrylic acid (AAc) and N-[3-(Dimethylamino)propyl]-methacrylamide (DMAPMA), and relevant mechanism has been delineated. Aqueous redox copolymerization of different molar ratios of AAc and DMAPMA at 41 ± 1 °C, leading to the formation of interlocked nanogels of ∼300 nm diameter, which acted as the building blocks of a series of superabsorbent hydrogels having robust, honey-comb type three-dimensional architecture. Monomer composition, monomer feed ratio and water content in feed has been found to be important factors in the development of the stable poly(AAc-co-DMAPMA) hydrogel membranes (PADMAs) without any active crosslinking agent. At the cues of pH change from 7.0 to 3.5, pulsatile swelling-deswelling behavior varied, ranging from ∼5900% to ∼60% (mass) respectively, underlining smart hydrogel characteristics needed for specific biomedical applications. Elastic modulus of the gels, equilibrated at pH 7.0, is recorded to be >15 kPa under uniaxial compression. Underlying mechanism of the formation of such robust three-dimensional structures in poly(AAc-co-DMAPMA) hydrogel membranes, and the origin of hierarchical ‘nano-to-macro’ scale morphological features has been proposed.     

Modeling Oxidation of Soot Particles Within a Laminar Aerosol Flow Reactor Using Computational Fluid Dynamics

This work examines the measurement of surface specific soot oxidation rates with the High Temperature Oxidation-Tandem Differential Mobility Analyzer (HTO-TDMA) method. The Computational Fluid Dynamics package CFD-ACE⁺ is used to understand particle flow, oxidation and size dependent particle losses in the laminar aerosol flow reactor using an Eulerian-Lagrangian framework. Decrease of DMA selected mono-disperse particle size distribution due to oxidation within the aerosol tube is modeled using fitted kinetic soot oxidation parameters. The effects of Brownian diffusion and thermophoresis on particle flow and loss to the reactor walls are evaluated. The position of peak particle diameter, which is used as an indicator to determine oxidation rate, is found to be independent of diffusion, thermophoresis and secondary flow effects, thus validating its use in deriving kinetic soot oxidation parameters. Diffusion does not affect the evolution of particle size distribution within the reactor. However, thermophoresis is found to be the dominant mechanism influencing both shape of particle size distribution and particle loss to the walls of the aerosol reactor. Simulations show reduced effects of secondary recirculating flows on the particle flow trajectories in a vertical furnace as compared to horizontal furnace orientation. This work highlights the importance of making accurate measurements of temperature within the modeling domain. Since gas temperature within the flow tube could not be measured with high radial resolution using radiation shielded thermocouple, the derived soot oxidation rate may be uncertain by a factor of 2. Importantly, CFD simulations suggest that a distribution of temperature and size-dependent particle reactivities may be present in the reactor, requiring further theoretical and experimental investigation.