Motional Averaging of Electric Field Gradients. Temperature Dependence of Nqr in Sodium Chlorate and Copper Chlorate

Es wird die Temperaturabhiingigkeit der CI35-Kernquadrupolresonanz in Natriumchlorat und Kupferchlorat im Temperature von 77 bis 300 °K untersucht. Es wird gezeigt, daß die Annahmen, die in der Theorie von Bayer gemacht werden, fur Chlorate gelten. Die Frequenz der Torsionsschwingungen der ClO3-Gruppe wird folglich mit dieser Theorie berechnet. Der berechnete Wert der Torsionsfrequenz stimmt gut mit vorhandenen Werten der Ramanspektroskopie überein.

Effect of electric arc discharge on hypersonic blunt body drag

Experimental results on the effect of energy deposition using an electric arc discharge, upstream of a 60° half angle blunt cone configuration in a hypersonic flow is reported.Investigations involving drag measurements and high speed schlieren flow visualization have been carried out in hypersonic shock tunnel using air and argon as the test gases; and an unsteady drag reduction of about 50% (maximum reduction) has been observed in the energy deposition experiments done in argon environment. These studies also show that the effect of discharge on the flow field is more pronounced in argon environment as compared to air, which confirms that thermal effects are mainly responsible for flow alteration in presence of the discharge.

Invariant magneto-electric and piezomagnetic coefficients

Invariant magneto-electric coefficients and invariant piezomagnetic coefficients are obtained for all the magnetic crystal classes.

Townsend's First Ionization Coefficients and Sparking Potentials in Crossed Electric and Magnetic Fields

Townsend's first ionization coefficients have been measured in corssed electric and magnetic fields for values of B/p ranging from 0.013 TESLA. TORR-1 to 0.064 TESLA.TORR-1 and for 103 x 102¿ E/p 331 x 102 V.M-1. TORR-1 in oxygen and for 122 x 102¿ E/pÂ488 x 102 V.M-1.TORR-1 for dry air. The values of effective collision frequencies determined from the equivalent pressure (pe) concept generally increase with E/p at constant B/p and decrease with increasing B/p at constant E/p. Effective collision frequencies determined from measured sparking potentials at high values of E/p increase with decreasing E/pe. The drift velocity and mean energy of electrons in oxygen in crossed electric and magnetic fields have been derived.

A new family of low-power CT/SUP 2/L circuits

A new family of low-power logic circuits, employing a multiemitter transistor input circuit and a modified complementary p-n-p n-p-n output stage, having almost the same performance as standard TTL circuits and suitable for IC use, is reported in this correspondence.

Multicarrier analysis of magnetotransport data at low and high electric fields

We present some results on multicarrier analysis of magnetotransport data, Both synthetic as well as data from narrow gap Hg0.8Cd0.2Te samples are used to demonstrate applicability of various algorithms vs. nonlinear least square fitting, Quantitative Mobility Spectrum Analysis (QMSA) and Maximum Entropy Mobility Spectrum Analysis (MEMSA). Comments are made from our experience oil these algorithms, and, on the inversion procedure from experimental R/sigma-B to S-mu specifically with least square fitting as an example. Amongst the conclusions drawn are: (i) Experimentally measured resistivity (R-xx, R-xy) should also be used instead of just the inverted conductivity (sigma(xx), sigma(xy)) to fit data to semiclassical expressions for better fits especially at higher B. (ii) High magnetic field is necessary to extract low mobility carrier parameters. (iii) Provided the error in data is not large, better estimates to carrier parameters of remaining carrier species can be obtained at any stage by subtracting highest mobility carrier contribution to sigma from the experimental data and fitting with the remaining carriers. (iv)Even in presence of high electric field, an approximate multicarrier expression can be used to guess the carrier mobilities and their variations before solving the full Boltzmann equation.

Influence of Temperature and High Electric Field on Power Consumption by Piezoelectric Actuated Integrated Structure

The influence of electric field and temperature on power consumption of piezoelectric actuated integrated structure is studied by using a single degree of freedom mass-spring-damper system model coupled with a piezoactuator. The material lead zirconate titanate, is considered as it is capable of producing relatively high strains (e.g., 3000 mu epsilon). Actuators are often subject to high electric fields to increase the induced strain produced, resulting in field dependant piezoelectric coefficient d(31), dielectric coefficient epsilon(33) and dissipation factor delta. Piezostructures are also likely to be used across a wide range of temperatures in aerospace and undersea operations. Again, the piezoelectric properties can vary with temperature. Recent experimental studies by physics researchers have looked at the effect of high electric field and temperature on piezoelectric properties. These properties are used together with an impedance based power consumption model. Results show that including the nonlinear variation of dielectric permittivity and dissipation factor with electric field is important. Temperature dependence of the dielectric constant also should be considered.

Observation of Peierls transition in nanowires (diameter similar to 130 nm) of the charge transfer molecule TTF-TCNQ synthesized by electric-field-directed growth

We report the growth of nanowires of the charge transfer complex tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) with diameters as low as 130 nm and show that such nanowires can show Peierls transitions at low temperatures. The wires of sub-micron length were grown between two prefabricated electrodes (with sub-micron gap) by vapor phase growth from a single source by applying an electric field between the electrodes during the growth process. The nanowires so grown show a charge transfer ratio similar to 0.57, which is close to that seen in bulk crystals. Below the transition the transport is strongly nonlinear and can be interpreted as originating from de-pinning of CDW that forms at the Peierls transition.

Electric Field–Enhanced Sensitivity of Grafted Ligands and Receptors

BACKGROUND: Particle-based agglutination tests consisting of receptors grafted to colloidal microparticles are useful for detecting small quantities of corresponding ligands of interest in fluid test samples, but detection limits of such tests are limited to a certain concentration and it is most desirable to lower the detection limits and to enhance the rate of recognition of ligands. METHODS: A mixture of receptor-coated colloidal microparticles and corresponding ligand was sandwiched between 2 indium tin oxide-coated glass plates. Electrohydrodynamic drag from an alternating-current electric field applied perpendicular to the plates increased the local concentration of the colloidal particles, improving the chances of ligand-receptor interaction and leading to the aggregation of the colloidal particles. RESULTS: With this technique the sensitivity of the ligand-receptor recognition was increased by a factor as large as 50. CONCLUSIONS: This method can improve the sensitivity of particle-based agglutination tests used in immuno-assays and many other applications such as immunoprecipitation and chemical, sniffing. (C) 2007 American Association for Clinical Chemistry.

Multi-Tone Testing of Linear and Nonlinear Analog Circuits using Polynomial Coefficients

A method of testing for parametric faults of analog circuits based on a polynomial representation of fault-free function of the circuit is presented. The response of the circuit under test (CUT) is estimated as a polynomial in the applied input voltage at relevant frequencies in addition to DC. Classification or Cur is based on a comparison of the estimated polynomial coefficients with those of the fault free circuit. This testing method requires no design for test hardware as might be added to the circuit fly some other methods. The proposed method is illustrated for a benchmark elliptic filter. It is shown to uncover several parametric faults causing deviations as small as 5% from the nominal values.

Slim P‐E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Sol-gel derived PbZrO3 (PZ) thin films have been deposited on Pt(111)/Ti/SiO2/Si substrate and according to the pseudotetragonal symmetry of PZ, the relatively preferred (110)t oriented phase formation has been noticed. The room temperature P‐E hysteresis loops have been observed to be slim by nature. The slim hysteresis loops are attributed to the [110]t directional antiparallel lattice motion of Pb ions and by the directionality of the applied electric field. Pure PZ formation has been characterized by the dielectric phase transition at 235 °C and antiferroelectric P‐E hysteresis loops at room temperature. Dielectric response has been characterized within a frequency domain of 100 Hz–1 MHz at various temperatures ranging from 40 to 350 °C. Though frequency dispersion of dielectric behaves like a Maxwell–Wagner type of relaxation, ω2 dependency of ac conductivity indicates that there must be G‐C equivalent circuit dominance at high frequency. The presence of trap charges in PZ has been determined by Arrhenius plots of ac conductivity. The temperature dependent n (calculated from the universal power law of ac conductivity) values indicate an anomalous behavior of the trapped charges. This anomaly has been explained by strongly and weakly correlated potential wells of trapped charges and their behavior on thermal activation. The dominance of circuit∕circuits resembling Maxwell–Wagner type has been investigated by logarithmic Nyquist plots at various temperatures and it has been justified that the dielectric dispersion is not from the actual Maxwell–Wagner-type response.

Analysis of Energy Quantization Effects on Single-Electron Transistor Circuits

In this paper, the effects of energy quantization on different single-electron transistor (SET) circuits (logic inverter, current-biased circuits, and hybrid MOS-SET circuits) are analyzed through analytical modeling and Monte Carlo simulations. It is shown that energy quantizationmainly increases the Coulomb blockade area and Coulomb blockade oscillation periodicity, and thus, affects the SET circuit performance. A new model for the noise margin of the SET inverter is proposed, which includes the energy quantization effects. Using the noise margin as a metric, the robustness of the SET inverter is studied against the effects of energy quantization. An analytical expression is developed, which explicitly defines the maximum energy quantization (termed as ``quantization threshold'') that an SET inverter can withstand before its noise margin falls below a specified tolerance level. The effects of energy quantization are further studiedfor the current-biased negative differential resistance (NDR) circuitand hybrid SETMOS circuit. A new model for the conductance of NDR characteristics is also formulated that explains the energy quantization effects.

Scattering polarization in the presence of magnetic and electric fields

The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Limiting cases of scattering under Zeeman effect, and Hanle effect in weak magnetic fields are discussed. The theory is general enough to handle scattering in intermediate magnetic fields (Hanle-Zeeman effect) and for arbitrary orientation of magnetic field. The quadrupolar electric field produces asymmetric line shifts, and causes interesting level-crossing phenomena either in the absence of an ambient magnetic field, or in its presence. It is shown that the quadrupolar electric field produces an additional depolarization in the Q/I profiles and rotation of the plane of polarization in the U/I profile over and above that arising from magnetic field itself. This characteristic may have a diagnostic potential to detect steady-state and time-varying electric fields that surround radiating atoms in solar atmospheric layers. (c) 2007 Elsevier Ltd. All rights reserved.

On the performance analysis of a class of neuron circuits

A new performance metric, Peak-Error Ratio (PER) has been presented to benchmark the performance of a class of neuron circuits to realize neuron activation function (NAF) and its derivative (DNAF). Neuron circuits, biased in subthreshold region, based on the asymmetric cross-coupled differential pair configuration and conventional configuration of applying small external offset voltage at the input have been compared on the basis of PER. It is shown that the technique of using transistor asymmetry in a cross-coupled differential pair performs on-par with that of applying external offset voltage. The neuron circuits have been experimentally prototyped and characterized as a proof of concept on the 1.5 mu m AMI technology.

On the performance analysis of a class of neuron circuits

A new performance metric, Peak-Error Ratio (PER) has been presented to benchmark the performance of a class of neuron circuits to realize neuron activation function (NAF) and its derivative (DNAF). Neuron circuits, biased in subthreshold region, based on the asymmetric cross-coupled differential pair configuration and conventional configuration of applying small external offset voltage at the input have been compared on the basis of PER. It is shown that the technique of using transistor asymmetry in a cross-coupled differential pair performs on-par with that of applying external offset voltage. The neuron circuits have been experimentally prototyped and characterized as a proof of concept on the 1.5 mu m AMI technology.