Effect of Zn, Sr, and Y Addition on Electrical Properties of PZT Thin Films

We have investigated methods to increase the efficiency of piezoelectric micromachined ultrasonic transducers (pMUTs). pMUTs are driven by a thin piezoelectric layer on a Si membrane. The efficiency of pMUTs can be increased using a film with better ferroelectric properties. We have used Zn, Sr, and Y doping on PZT-based thin films along the morphotropic phase boundary (MPB) composition to increase their piezoelectric properties. The results obtained were then extended to compositions on both sides of the MPB. The sol–gel method was used to prepare precursor solutions, which were then spin coated on a Pt(100)/Ti/SiO₂/Si substrate to prepare the PZT thin films. It was found that Zn and Sr together had the most significant effect on the ferroelectric properties in which a saturation polarization of 108 μC/cm² and remanent polarization of 54 μC/cm² were achieved.     

Selective recognition of fenbufen by surface-imprinted silica with iniferter technique

Fenbufen, a member of nonsteroidal antiinflammatory drugs and widely used in the treatment of rheumatoid arthritis was imprinted by utilizing a zwitterionic polymeric format, N-[(phenylenediammonium) maleimidopropane sulfonate] copolymer. Imprinting was carried out by grafting polymer on a photoiniferter modified silica gel via living radical polymerization. Electrostatic interactions along with complementary H-bonding and other hydrophobic interactions inducing additional synergetic effect between the template (fenbufen) and the imprinted surface led to the formation of imprinted sites. Grafted molecularly imprinted polymer (MIP) was characterized by FTIR and surface area measurements besides the recognition, rebinding and selectivity studies. The surface area, pore diameter and pore volume of the MIP are 259.06 m²/g, 4.99 nm and 0.32 cm³/g, respectively. The MIP was able to selectively and specifically take up fenbufen quantitatively. Hence, a facile, specific and selective technique using surface-grafted specific molecular contours developed for specific and selective uptake of fenbufen in the presence of various interferrants, in different kinds of matrices is presented.     

Triple Band Annular Ring Loaded Stacked Circular Patch Microstrip Antenna

In this paper a novel structure of annular ring loaded stacked circular patch microstrip antenna is theoretically analysed to observe various parameters such as return loss, input impedance, gain, directivity and radiation pattern. It is found that antenna possess three band of operation which signify the compactness and multiband operation of antenna. The antenna is resonating at three operating frequencies 1.720, 2.950, 3.060 GHz. The proposed theory is verified by simulation using Ansoft’s HFSS and theoretical results are in good agreement with simulated results. The antenna is useful for multi-services operations such as WLAN, GSM, UMTS, and WiMAX services.     

Nanosuspension of efavirenz for improved oral bioavailability: formulation optimization,in vitro,in situ and in vivo evaluation

Context: Nanosuspensions (NSs) of poorly water-soluble drugs are known to increase the oral bioavailability.

Objectives: The purpose of this study was to develop NS of efavirenz (EFV) and to investigate its potential in enhancing the oral bioavailability of EFV.

Materials and methods: EFV NS was prepared using the media milling technique. The Box–Behnken design was used for optimization of the factors affecting EFV NS. Sodium lauryl sulfate and PVP K30 were used to stabilize the NS. Freeze-dried NS was completely re-dispersed with double-distilled filtered water.

Results: Mean particle size and zeta potential of the optimized NS were found to be 320.4?±?3.62?nm and –32.8?±?0.4 mV, respectively. X-ray diffraction and differential scanning calorimetric analysis indicated no phase transitions. Rate and extent of drug dissolution in the dissolution medium for NS was significantly higher compared to marketed formulation. The parallel artificial membrane permeability assay revealed that NS successfully enhanced the permeation of EFV. Results of in situ absorption studies showed a significant difference in absorption parameters such as K_a, t_1/2 and uptake percentages between lyophilized NS and marketed formulation of EFV. Oral bioavailability of EFV in rabbits resulting from NS was increased by 2.19-fold compared to the marketed formulation.

Conclusion: Thus, it can be concluded that NS formulation of EFV can provide improved oral bioavailability due to enhanced solubility, dissolution velocity, permeability and hence absorption.     

Tolerance allocation of assemblies using fuzzy comprehensive evaluation and decision support process

Tolerances play an important role in product fabrication and have a significant impact on manufacturing costs. The factors affecting manufacturing cost (geometry, material, etc.) of a part are fuzzy or subjective in nature since they have no appropriate numerical measure. This paper proposes a framework that overcomes the drawbacks of traditional tolerance control methods and reduces subjectivity via fuzzy comprehensive evaluation and conjoint analysis. In the fuzzy comprehensive evaluation process, the relationship between the machining costs and part tolerance is expressed through a mathematical formula, with the objective of minimizing the total machining cost. The conjoint analysis method is introduced to provide a systematic method of deciding weights for each of the factors in the tolerance allocation procedure. The application of the framework is demonstrated with practical engineering problems of allocating tolerances of an accumulator’s O-ring seal and a clutch assembly.     

Synthesis and characterization of partially fluorinated hydrophobic–hydrophilic multiblock copolymers containing sulfonate groups for proton exchange membrane

A new hydrophobic–hydrophilic multiblock copolymer has been successfully synthesized based on the careful coupling of a fluorine terminated poly(arylene ether ketone) (6FK) hydrophobic oligomer and a phenoxide terminated disulfonated poly(arylene ether sulfone) (BPSH) hydrophilic oligomer. ¹⁹F and ¹H NMR spectra were used to characterize the oligomers’ molecular weights and multiblock copolymer's structure. The comparison of the multiblock copolymer ¹³C NMR spectrum with that of the random copolymer showed that the transetherification side reaction was minimized in this synthesis. The morphologies of membranes were investigated by tapping mode atomic force microscopy (AFM), which showed that the multiblock membrane acidified by the high temperature method has sharp phase separation. Membrane properties like protonic conductivity, water uptake, and self-diffusion coefficient of water as a function of temperature and relative humidity (RH) were characterized for the multiblock copolymer and compared with ketone type random copolymers at similar ion exchange capacity value and Nafion^® controls. The multiblock copolymers are promising candidates for proton exchange membranes especially for applications at high temperatures and low relative humidity.     

Auto-configuration of Physical Cell ID in LTE femtocellular systems using Self Organizing Networks

The commercial success of cellular networks, combined with advances in digital electronics, signal processing, and telecommunications research have lead to the design of next generation 4G-based long term evolution (LTE) wireless systems. The key essence of these emerging, LTE cellular systems lie in deployment of multiple femtocells for improved coverage and higher data rates. However, the arbitrary deployment of a wide number of femtocells makes the configuration, management and planning of LTE systems quite complex and challenging. In order to support dynamic and efficient network configuration, every cell needs to be assigned a particular Physical Cell ID (PCID). In this paper we show that the dynamic, optimal PCID allocation problem in LTE systems is NP-complete. Subsequently we provide a near-optimal solution using Self-Organizing Networks which models the problem using new merge operations and explores the search space using a suitable randomized algorithmic approach. We also discuss two feasible options for dynamic auto-configuration of the system and analyze the algorithm to prove its convergence. Simulation results point out that our proposed near-optimal solution dynamically achieves ～85?90 % of global optimal auto-configuration in computationally feasible time.     

Phosphatidylinositol-3-OH kinase as a direct target of Ras

Ras (p21ras) interacts directly with the catalytic subunit of phosphatidylinositol-3-OH kinase in a GTP-dependent manner through the Ras effector site. In vivo, dominant negative Ras mutant N17 inhibits growth factor induced production of 3' phosphorylated phosphoinositides in PC12 cells, and transfection of Ras, but not Raf, into COS cells results in a large elevation in the level of these lipids. Therefore Ras can probably regulate phosphatidylinositol-3-OH kinase, providing a point of divergence in signalling pathways downstream of Ras.     

Protein-lipid interactions and enzyme requirements for light subtype generation on cycling reconstituted surfactant

Surfactant convertase is required for conversion of heavy density (H) natural surfactant to light density (L) subtype during cycling in vitro, a technique that reproduces surfactant metabolism. To study mechanisms of H to L conversion, we prepared liposomes of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG), or the phospholipids (PL) in combination with either surfactant protein A (SP-A), surfactant protein B (SP-B), or both SP-A and SP-B. Phospholipids alone showed time-dependent conversion from heavy to light subtype on cycling in the absence of convertase, which was decreased by adding SP-B, but not SP-A, to phospholipids (p < 0.01 for PL+SP-B, or PL+SP-A+SP-B vs. PL, or PL+SP-A). The ultrastructure, surface activity, buoyant density, and L subtype generation on cycling PL+SP-A+SP-B with partially purified convertase or with phospholipase D were similar to those of natural TM. In conclusion, a reconstituted surfactant mimics the behavior of natural surfactant on cycling, and reveals that interaction of SP-B with phospholipids decreases L subtype generation. In addition, esterase/ phospholipase D activity is required for conversion of heavy to light subtype on cycling.