Influence of reaction conditions on the formation of nanotubes/nanoparticles of polyaniline in the presence of 1‐amino‐2‐naphthol‐4‐sulfonic acid and applications as electrostatic charge dissipation material

BACKGROUND: Poly(1‐amino‐2‐naphthol‐4‐sulfonic acid) and its copolymers with aniline are a new class of conducting polymers which can acquire intrinsic protonic doping ability, leading to the formation of highly soluble self‐doped homopolymers and copolymers. Free ? OH and ? NH₂ groups in the polymer chain can combine with other functional groups that could be present in protective paints which can thus be successfully used as antistatic materials. RESULTS: This paper reports the formation of nanotubes of polyaniline on carrying out oxidative polymerization of aniline in the presence of 1‐amino‐2‐naphthol‐4‐sulfonic acid (ANSA) in p‐toluenesulfonic acid (PTSA) as an external dopant. The presence of ? SO₃H groups in the ANSA comonomer allows the copolymer to acquire intrinsic protonic doping ability. The polymerization mechanism was investigated by analysing the ¹H NMR, ¹³C NMR, Fourier transform infrared and X‐ray photoelectron spectra of the copolymers and homopolymers, which revealed the involvement of ? OH/? NH₂ in the reaction mechanism. Scanning and transmission electron microscopy showed how the reaction route and the presence of a dopant can affect the morphology and size of the polymers. Static decay time measurements were also carried out on conducting copolymer films prepared by blending of 1 wt% of copolymers of ANSA and aniline with low‐density polyethylene (LDPE) which showed a static decay time of 0.1 to 0.31 s on dissipating a charge from 5000 to 500 V. CONCLUSION: Copolymers of ANSA with aniline were synthesized in different reaction media, leading to the formation of nanotubes and nanoparticles of copolymer. Blends of 1 wt% of PTSA‐ and self‐doped copolymers of ANSA and aniline with LDPE can be formulated into films with effective antistatic properties. Copyright © 2009 Society of Chemical Industry     

Microstructure and electrical characterisations of K-modified PLZT

Potassium-modified PLZT [Pb_0.92(La_{1 – z}K_z)_0.08(Zr_0.60Ti_0.40)_{0.98 + 0.04z}O₃ (z = 0.0, 0.1, 0.3, 0.5, 0.7)] ceramics were synthesised using sol-gel technique. Preliminary structural and microstructural parameters were determined using XRD, SEM and TEM techniques. Detailed studies of dielectric properties at 10 kHz in a wide temperature range suggest that the compounds have diffuse phase transition of second order. Studies of spontaneous polarisation, pyroelectric and piezoelectric properties yielded data for devices.     

Vulnerabilities in Chen and Deng's RFID mutual authentication and privacy protection protocol

As incorporation of RFID (Radio Frequency IDentification) tags in a wide variety of applications increase, there is a need to ensure the security and privacy of the entity to which these tags are attached. Not surprisingly, this is a very active area as attested by the large number of related published research literature. Recently, the journal engineering applications of artificial intelligence published a paper by Chen and Deng (2009) where the authors propose a mutual authentication protocol for RFID. This protocol has fundamental flaws that can be readily taken advantage by a resourceful adversary. We identify and discuss these vulnerabilities and point out the characteristics of this protocol that exposes it to these vulnerabilities.     

Synthesis and analysis of lead-free tungsten bronze ferroelectrics

The polycrystalline Ba₂Sr₃GdTi₃V₇O₃₀, a member of tungsten bronze structural family, was prepared by a solid-state reaction method at high temperature (calcination and sintering temperatures at 950 and 1,000 °C, respectively). Preliminary structural study showed that the compound has orthorhombic crystal structure at room temperature. Study of surface morphology of the compound by scanning electron microscopy exhibits the uniform grain distribution on the surface of the sample with less number of voids. The dielectric anomaly observed at 313 °C is considered as a ferroelectric-paraelectric phase transition temperature which has been confirmed by appearance of hysteresis loop at room temperature. The trend of variation of ac conductivity with inverse of absolute temperature provides the nature of conduction mechanism in the material. The different value of activation energy in different temperature regions suggests that the conduction process in the material is of mixed-type (i.e., ionic–polaronic and space charge due to the oxygen ion vacancies).     

Generalized Mathematical Modeling of N-Phase Power Systems

ABSTRACT

The analysis of the polyphase power systems is normally carried out by assuming a perfectly balanced system. However, power system is generally unbalanced because of various reasons. Therefore, it is desirable to analyse the power system taking imbalances into account. Hence, it is necessary to develop mathematical formulations of various components of the power systems in phasor co-ordinates. In this paper, detailed mathematical models for general n-phase components have been developed. These models will be useful for conducting the steady state as well as the transient analysis of the multiphase systems in phasor co-ordinates. Finally, the paper concludes with the discussion on the findings based upon these models.     

Less common causes of carpal tunnel syndrome

A new DRB3*02 allele (DRB3*0207) was detected in a female Luxembourg Caucasian blood donor by sequence-based typing. The new allele differs from DRB3*0202 by two substitutions in codon 57 resulting in an amino acid change from a charged aspartic acid to a neutral valine. This is the first example of a DRB3 allele pair differing only at codon 57.     

Synthesis,structure and characterization of ceramic Ca4Bi2Ti4Nb6O30

The polycrystalline samples of Ca₄Bi₂Ti₄Nb₆O₃₀ (herein designated CBTN) were synthesized by the conventional ceramic method. Preliminary X-ray structural study of the compound showed the formation of a single phase solid solution having orthorhombic structure in the paraelectric phase. Measurements of the dielectric constant (ε) and dielectric loss (tan δ) as a function of temperature (−180–200°C) at 1 kHz and 10 kHz and also as a function of frequency (10² Hz to 10⁴ Hz) at five different temperatures [−180°C, −40°C, − 10°C 26°C (room temperature) and 75°C] have shown a dielectric anomaly and a phase transition at − 13 ±1°C in CBTN.     

High-Performance Software Protection Using Reconfigurable Architectures

One of the key problems facing the computer industry today is ensuring the integrity of end-user applications and data. Researchers in the relatively new field of software protection investigate the development and evaluation of controls that prevent the unauthorized modification or use of system software. While many previously developed protection schemes have provided a strong level of security, their overall effectiveness has been hindered by a lack of transparency to the user in terms of performance overhead. Other approaches take to the opposite extreme and sacrifice security for the sake of this transparency. In this work we present an architecture for software protection that provides for a high level of both security and user transparency by utilizing field programmable gate array (FPGA) technology as the main protection mechanism. We demonstrate that by relying on FPGA technology, this approach can accelerate the execution of programs in a cryptographic environment, while maintaining the flexibility through reprogramming to carry out any compiler-driven protections that may be application-specific.     

Characterization and Studies on Hydro Dynamically Stable Operation of an Angular Jet SOG for COIL

Chemical oxygen-iodine Laser (COIL) is one of the fast emerging high power laser source for near Infrared (λ=1.315μm) laser generation. The heart of the system is the singlet oxygen generator (SOG) which is a pumping source for this laser. A Jet type SOG with a novel approach was designed and fabricated. Singlet oxygen was taken out of the SOG at an angle of 40° thus avoiding the carry over of droplets, which is one of the major drawbacks of horizontal system. The preliminary results have been reported in our earlier publication. The present paper discusses the performance of this generator for various operational conditions viz. diluent's gas nitrogen / helium, basic hydrogen peroxide composition, generator pressure and gas velocity. Further, conditions for the stable operation from generator as well as chlorine injection point of view have been identified.