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     

The steady-state kinetics of parallel reaction networks

The conventional kinetic analysis of an overall reaction (OR) is limited to a single sequential pathway of molecular steps at a time, based either on the general quasi-steady state (QSS) approach of Bodenstein, or on the much simpler but limited Langmuir–Hinshelwood–Hougen–Watson (LHHW) approach based on assuming a single rate-determining step (RDS), the remaining being quasi-equilibrated (QE). We recently described a new algebraic methodology for deriving the QSS rate expression for a reaction sequence, which allowed interpretation of the final result in an Ohm's law form, i.e., OR rate=OR motive force/OR resistance of an equivalent electric circuit, where the consecutive mechanistic steps represent resistors in series. Here, we propose a similar Ohm's law form of QSS rate for a reaction system involving parallel pathways, whose equivalent electrical circuit derives directly from the reaction route (RR) Graph of its mechanism, as proposed earlier by us. The results are exact for a reaction network with mechanistic steps linear in intermediates concentrations, while they are approximate, albeit accurate, for non-linear step kinetics. We further show how the LHHW methodology, combined with the concept of intermediate reaction might be utilized to obtain the step resistances involved. For illustration, we utilize the relatively simple examples of: (1) the gas-phase hydrogen–bromine non-catalytic reaction (non-linear kinetics), and (2) zeolite catalyzed N₂O decomposition reaction (linear kinetics). However, the approach is useful for more complex non-catalytic, catalytic and enzymatic reactions networks as well.     

Autoignition and front propagation in low temperature combustion engine environments

In this paper, we computationally investigate the fundamental aspects of autoignition and subsequent combustion phenomena in low temperature combustion (LTC) engine environments using direct numerical simulations (DNS). In particular, the effects of thermal and equivalence ratio stratification on the autoignition and subsequent front propagation in high pressure and stratified hydrogen-air turbulent mixtures are studied using detailed chemistry. Depending on fuel injection timing, exhaust gas recirculation, and wall heat loss, different correlations between temperature (T) – equivalence ratio (?) fields can exist prior to the major heat release event. Here, we investigate three cases with different initial T–? correlations: (A) a baseline case of a uniform composition with temperature inhomogeneities only, (B) uncorrelated T–? fields, and (C) negatively-correlated T–? fields. Numerical diagnostics are developed based on an appropriately defined Damköhler number to distinguish different modes of heat release. It is found that the majority of heat release in the baseline case and the uncorrelated case occurs during the front propagation in the form of both spontaneous ignition fronts as well as deflagration waves, whereas the negatively correlated case ignites predominantly homogeneously.     

Morphology Controlled Magnesium Ethoxide: Influence of Reaction Parameters and Magnesium Characteristics

Controlled reaction of magnesium with ethanol was found to produce morphological magnesium ethoxide. The scanning electron microscopy studies indicate that particles of magnesium ethoxide grow on the surface of magnesium granules and are detached from the surface as a result of shearing and collisions during the reaction. Particle characteristics of magnesium show influence on the kinetics of the reaction as well as morphological characteristics of magnesium ethoxide. Impact of other process parameter variations on the magnesium ethoxide particle characteristics is also studied. The reaction rate, agitation speed, and type of agitator show influence on the product characteristics, whereas no influence of change in reaction pressure is observed.     

A jolt from the blue? [Microwave Surfing]

Pacemakers and implantable cardioverter defi brillators (ICDs) are routinely implanted in U.S. patients [2], saving and prolonging many lives by helping regulate cardiac function. When one of these devices (newer models) is surgically placed below the patient's skin, it has the capability of communicating with a nearby external programming unit both for telemetering data from the patient (physiological data as well as identifi cation information) and for receiving instructions that modify the operational parameters of the device, frequently over an unencrypted channel. There's the rub.     

Blood mercury in workers exposed to the preparation of mercury cadmium telluride layers on cadmium telluride base

Study was conducted in a group of 32 persons engaged in liquid phase epitaxial growth of mercury cadmium telluride (MCT) layers for nearly 11 years. Airborne mercury concentrations in work environment have been exceeding the threshold limit value of 0.05 mg/m3 recommended by ACGIHD. Hg concentration in workplace during peak working hours remained between 0.04-0.08 mg/m3. Findings were compared with 32 unexposed referents. Mercury value was estimated 1.60 +/- 0.20 (mean +/- SD) in control, and in Phase I and II, 10.72 +/- 1.34 ng Hg/ml and 8.08 +/- 1.15 ng Hg/ml of blood respectively. Results indicate a fall in blood mercury level during the second phase of study. But the values did not return to normal even after a gap of 3 months. An individual who met with a mercury accident showed 226 ng Hg/ml of blood which decreased to 25 ng/ml after 3 months. It is inferred from the present study that Hg level has increased significantly in MCT workers during working period, and also in non-working period, the values were higher than controls.     

Aggregation in sensor networks: an energy–accuracy trade-off

Wireless ad hoc sensor networks (WASNs) are in need of the study of useful applications that will help the researchers view them as distributed physically coupled systems, a collective that estimates the physical environment, and not just energy-limited ad hoc networks. We develop this perspective using a large and interesting class of WASN applications called aggregation applications. In particular, we consider the challenging periodic aggregation problem where the WASN provides the user with periodic estimates of the environment, as opposed to simpler and previously studied snapshot aggregation problems. In periodic aggregation our approach allows the spatial–temporal correlation among values sensed at the various nodes to be exploited towards energy-efficient estimation of the aggregated value of interest. Our approach also creates a system level energy vs. accuracy knob whereby the more the estimation error that the user can tolerate, the less is the energy consumed. We present a distributed estimation algorithm that can be applied to explore the energy–accuracy subspace for a subclass of periodic aggregation problems, and present extensive simulation results that validate our approach. The resulting algorithm, apart from being more flexible in the energy–accuracy subspace and more robust, can also bring considerable energy savings for a typical accuracy requirement (fivefold decrease in energy consumption for 5% estimation error) compared to repeated snapshot aggregations.     

Energy efficiency analysis of air cycle heat pump dryers

In this paper, the feasibility of an air heat pump (reversed Brayton) cycle for tumbler clothes dryers is investigated. The goal is to increase the energy efficiency as compared to conventional electrically heated driers. Relatively simple models were used to compare the energy efficiency of the heat pump drier with that of a conventional air vented drier. The components were modeled using overall performance indices and thermodynamic relations. An air cycle heat pump dryer with practical components was found to be capable of significant efficiency improvements as compared with conventional dryers.