AC Parameters Research Articles

Ac Conductivity Study of Hexanoyl Chitosan-LiCF<sub>3</sub>SO<sub>3</sub>-EC-Al<sub>2</sub>O<sub>3</sub> Nanocomposite Polymer Electrolytes

Films of hexanoyl chitosan-based polymer electrolyte were prepared by solution casting technique. LiCF3SO3, EC and Al2O3 were employed as the doping salt, plasticizer and filler, respectively. The ac conductivity of the electrolyte system under investigation has been studied in the frequency range from 100 Hz to 1 MHz over the temperature range from 273 K to 333 K. The exponent s in the Jonscher’s universal power law equation was analyzed as a function of temperature. The analysis suggests that the conduction mechanism for the nanocomposite electrolyte system can be interpreted based on the correlated barrier hopping (CBH) model. The ac parameters such as the barrier height, WM and cut-off hopping distance, Rmin were calculated. The values of WM and Rmin are found to decrease with increasing temperature in the same manner as the exponent s.

Thickness dependence of the dielectric properties of thermally evaporated Sb2Te3 thin films

Sb2Te3 thin films of different thickness (23 – 350 nm) were prepared by thermal evaporation technique. The thickness dependence of the ac conductivity and dielectric properties of the Sb2Te3 films have been investigated in the frequency range 10 Hz- 100 kHz and within the temperature range 293-373K. Both the dielectric constant ϵ1 and dielectric loss factor ϵ2 were found to depend on frequency, temperature and film thickness. The frequency and temperature dependence of ac conductivity (σac(ω)) has also been determined. The ac conductivity of our samples satisfies the well known ac power law; i.e., σac(ω) ∝ ωs where s<1 and independent of the film thickness. The temperature dependence of ac conductivity and parameter s is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energies were evaluated for various thicknesses. The temperature coefficient of the capacitance (TCC) and permitivity (TCP) were determined as a function of the film thickness. The microstructure of the samples were analyzed using X-ray diffraction (XRD). This results are discussed on the base of the differences in their morphologies and thicknesses. The tendency for amorphization of the crystalline phases becomes evident as the film thickness increases.

Serial ferroelectric memory ionizing radiation effects and annealing characteristics

Ferroelectric random memory was irradiated and annealed by 60Co-rays, total ionizing dose (TID) failure mechanism and annealing characteristics of the device were analyzed. DC, AC and function parameters of the memory were tested in radiation and annealing by very large scale integrated cicuit (VLSI) test system, the radiation-sensitive parameters were obtained through analyzing the test data. Ionizing radiation produced a large number of oxide trapped charges, leading MOS transistor threshold to the negative drift in memory peripheral control circuit. Additional electric field was introduced in the ferroelectric film, and leakage current was produced since the Schottky emission or space-charge-limited current occurred. The number of shallower levels and metastable state oxide trapped charges are more than the deep level oxide trapped charge, so that the device functions and the radiation-sensitive parameters were restored in the annealing.

Study on Notch Sensitivity of Fracture Properties of Concrete Containing Nano‐SiO2 Particles and Fly Ash

The fracture parameters and fracture relational curves of the concrete containing nano‐SiO2 and fly ash with different relative notch depth of the notched beam specimens were measured by means of three‐point bending method. The results indicate that the relative notch depth of the notched specimens has great effect on ac, , , GF, CMODc, and the fracture relational curves of the concrete containing nano‐SiO2 and fly ash. There is a tendency of increase in ac and CMODc with the increase of relative notch depth, while , , and GF are decreasing gradually with the increase of relative notch depth of the notched beam specimens. Besides, when the relative notch depth increases from 0.2 to 0.5, the nonlinear stage of the curve becomes shorter and shorter, and the descent stage of the curve becomes sharper and sharper. The fracture parameters of ac, , , GF, and CMODc and the fracture curves are sensitive to the relative notch depth, while CTODc may be not sensitive to the relative notch depth of the specimens of the concrete containing nano‐SiO2 and fly ash.

Effectiveness of the Computed Analysis of Electroglottographic Signals in Muscle Tension Dysphonia

Objective: To investigate the usefulness of electroglottography (EGG) parameters in the diagnosis and estimation of efficacy of voice therapy for muscle tension dysphonia (MTD). Patients and Methods: Nineteen MTD participants, an equivalent number of dysphonic (‘organic’) patients with vocal fold lesions and as many normal speakers were enrolled. Acoustic (Ac) and EGG signals during sustained phonation were recorded simultaneously. The period and amplitude perturbation quotient of both signals, the closed quotient (CQ) of EGG signals (mean CQ) and its standard deviation (CQSD) were calculated, and subsequently compared among the three groups. These parameters in the MTD group were compared before and after voice therapy. Results: The perturbation measures of both signals in the MTD group were either as high as or significantly higher than those in the organic group or the control group, respectively. Both the Ac and EGG parameters after therapy significantly decreased. The CQSD, but not mean CQ, also decreased after therapy. Conclusion: EGG parameters related to the regularity of vocal fold vibration, but not to the degree of vocal fold contact (mean CQ), are useful for the diagnosis and estimation of voice therapy outcome in MTD.

Abstract 1704: AC electrokinetic isolation of cell free high molecular weight DNA (CF-HMW DNA) from serum

Abstract Recent reports of CF-HMW DNA in a variety of diseases has led to interest in its use as a prognostic biomarker, a diagnostic or screening tool for cancer. Apoptotic DNA (&amp;lt;200bp) is present in the circulation of normal healthy individuals. In cancer, unregulated cell growth leads to uncontrolled cell death, or necrosis, which produces HMW DNA (&amp;gt;500bp) that is then trafficked into circulation. Dielectrophoresis, or DEP (movement of particles in a non-uniform AC electric field), based electrokinetic techniques have been used for protein biomarker screening, cell separation, and DNA manipulation. Using specific DEP frequencies, analytes are moved to known locations (high or low field region) based on their inherent dielectric properties. The process allows specific nano-sized particles to be highly concentrated into high field regions, while micron-size cells are held weakly in low field regions. With fluidic washing, cells can be removed while nano-sized particles are held in high field regions. This method can effectively act as a CF-HMW DNA enrichment process for biological fluids. Unfortunately, DEP does not work well in (high conductance) physiological buffers, requiring significant dilution of the sample and, as a result, the target analyte concentration. Here, we describe a novel AC electrokinetic (ACE) technique using a custom microelectrode array and AC parameters to isolate and analyze CF-HMW DNA from high conductance serum. DNA from normal serum samples and the A549 cell line were isolated using Qiagen kits to determine initial DNA quantities. Normal sera were spiked with A549 cell line DNA at concentrations from 0 to 500 ng/ml and subjected to a 20 minute ACE protocol. DNA isolation was visualized in situ using SYBR Green I fluorescence and then eluted for use in secondary analyses. Results showed minimal fluorescence from samples without spike whereas A549 DNA spiked samples showed concentration-dependent fluorescence on the microelectrodes. After elution, levels of DNA were quantitated using ALU-sequence based qPCR and K-ras mutational status was confirmed by ABI CastPCR. Future experiments will compare CF-HMW DNA levels from normal and cancer patients across a variety of solid tumors. The ACE technique enables rapid isolation and detection of CF-HMW DNA directly from biological fluids without prior sample prep and has broad utility for diagnosis and monitoring of cancer and other diseases in which CF-HMW DNA may be used as a marker. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1704. doi:1538-7445.AM2012-1704

Double-balanced mixer based on MOSFETs

An analysis of an integrated MOSFET-based Gilbert-cell mixer is presented. Methods are described for calculating its major ac and dc parameters, including those characterizing conversion gain, noise performance, and nonlinear distortions. The performance of the proposed implementation is estimated. Comparisons are made with computer simulations.

Photon-assisted shot noise through a quantum dot coupled to Luttinger liquid

Photon-assisted shot noise through a quantum dot coupled to Luttinger liquid leads is considered using nonequilibrium-Green-function-method. We find that the effect of ac field on the differential shot noise is different for different intralead electron interaction. The inelastic channels associated with photon-assisted-tunneling can dominate electron transport for some ac parameters.

Procedure for building a MOS transistor high frequency small-signal model

This paper examines a procedure for building a MOS transistor small-signal equivalent circuit for the high frequency range. Procedures are proposed for determining the ac and dc parameters. The simulation results and experimental data are also presented.

Dielectric dispersion in lithium–bismuth-borate glasses

Glasses with compositions xBi 2O 3–(75–x) B 2O 3–25Li 2O with, x = 0, 5, 20, 25,30,35,40 mol % have been prepared using the normal melt quenching technique. The dielectric constant (έ) dielectric loss tangent tan δ, electric modulus behaviour was studied as a function of temperature in the frequency range 0.1–100 kHz. The detailed analysis of the results showed that the dielectric dispersion consists of both dipolar and interfacial polarization. Also the activation energy of the dielectric relaxation process from the electric modulus measurements was calcaulated. Measurements of the ac conductivity as a function of frequency at different temperatures indicated that the correlated barrier hopping (CBH) model is the most suitable mechanism for the ac conduction behaviour. The ac parameters, such as hopping distance ( R, R min), polaron binding energy ( U M ) and Columbic barrier height ( U h ) were calculated.

Resonance fluorescence in driven quantum dots: Electron and photon correlations

We study the counting statistics for electrons and photons being emitted from a driven two-level quantum dot. Our technique allows us to calculate their mutual correlations as well. We study different transport configurations by tuning the chemical potential of one of the leads to find that the electronic and photonic fluctuations can be externally manipulated by tuning the ac and transport parameters. We also propose special configurations where electron-photon correlation is maximal meaning that spontaneous emission of photons with a well-defined energy is regulated by single electron tunneling. Interesting features are also obtained for energy-dependent tunneling.

Measurement and comparison of silicon p-i-n-photodiodes with ac impedance at different voltages

The dark alternating current (ac) parameters of commercially available silicon p-i-n-photodiodes are measured and compared at room temperature both in forward and reverse bias using the impedance spectroscopy technique. The ac behavior of the photodiodes is found to be almost the same. For bias voltages in the range from −0.8 to 0.0 V, the typical photodiode behaves like a pure capacitor. For higher voltages (V >-0.2 V) the impedance spectra are nearly semicircular and typically distorted on the high frequency side. At 0.2 V the distortion apparently arises from one of the two interfaces. However, at high bias voltages the nature of the distortion is attributed to the variation of photodiode capacitance and resistance with measurement frequency.

Continuous current and surface potential models for undoped and lightly doped double-gate metal-oxide-semiconductor field-effect transistors

We have introduced a continuous, explicit, surface potential model for symmetric undoped and lightly doped double gate metal-oxide-semiconductor field-effect transistor devices. The surface potential model considered both hole and electron quasi-Fermi potential effects. An explicit current model has been introduced in terms of both source and drain charge densities at which hole and electron quasi-Fermi level or IMREFs are defined. The introduced models are directly related to the device biasing and device structure without the need for fitting parameters. Both of the surface potential and current models are continuous from below to above threshold and from linear to saturation of operation regimes. Good agreement has been obtained when our analytical models are compared to numerical results. The effects of hole IMREF on the small-signal (or ac) parameters are also reported. We predicted that the presence of holes has raised the saturation voltage. Also, we have observed from the gate capacitance curve that the hole IMREF should be taken into our account for low frequency applications.

Dielectric investigations and ac conductivity of polyvinyl alcohol films doped with europium and terbium chloride

Differential scanning calorimetry (DSC) was used to identify the phase transitions of polyvinyl alcohol (PVA) doped with europium chloride (EuCl 3) and terbium chloride (TbCl 3). The dielectric constant and the loss tangent behavior of the investigated samples were studied as a function of temperature in the frequency range 1–100 kHz. The detailed analysis of the results showed that dielectric dispersion consists of both dipolar and interfacial polarization. The temperature coefficient of permittivity (TCP) and the electrical dipole moment ( μ) were calculated. Also, the activation energy for the glass relaxation process from the dielectric loss tangent measurements was calculated. Measurements of the ac conductivity as a function of frequency at different temperatures indicated that the correlated barrier hopping (CBH) model is the most suitable mechanism for the ac conduction behavior. The ac parameters, such as hopping distance ( R, R min), polaron binding energy ( U M) and Coulombic barrier height ( U h) were calculated.

Tunnel spectroscopy in ac-driven quantum dot nanoresonators

Electronic transport in a triple quantum dot shuttle device in the presence of an ac field is analyzed within a fully quantum mechanical framework. A generalized density matrix formalism is used to describe the time evolution for electronic state occupations in a dissipative phonon bath. In the presence of an ac gate voltage, the electronic states are dressed by photons and the interplay between photon and vibrational sidebands produces current characteristics that obey selection rules. Varying the ac parameters allows to tune the tunneling current features. In particular, we show that coherent destruction of tunneling can be achieved in our device.

Measurement and comparison of complex impedance of silicon p-i-n photodiodes at different temperatures

The dark alternating current (ac) parameters of BPW34 and BPW41 (Vishay-Telefunken) silicon p-i-n photodiodes are measured and compared at different temperatures using the impedance spectroscopy technique. The impedance plots are nearly semicircular and typically distorted on the high frequency side. For BPW41, the distortion apparently arises from one of the two interfaces as expected for a typical p-i-n device. However, for BPW34, the presence of the distortion is attributed to the variation of photodiode capacitance and resistance with measurement frequency.

Technology CAD for germanium CMOS circuit

Process simulation for germanium MOSFETs (Ge-MOSFETs) has been performed in 2D SILVACO virtual wafer fabrication (VWF) suite towards the technology CAD for Ge-CMOS process development. Material parameters and mobility models for Germanium were incorporated in simulation via C-interpreter function. We also report on the device design issues along with the DC and RF characterization of the bulk Ge-MOSFETs, AC parameter extraction and circuit simulation of Ge-CMOS. Simulation results are compared with bulk-Si devices. Simulations predict a cut-off frequency, f T of about 175 GHz for Ge-MOSFETs compared to 70 GHz for a similar gate-length Si MOSFET. For a single stage Ge-CMOS inverter circuit, a GATE delay of 0.6 ns is predicted.

Quantitative elucidation of macrocyclic effect on extraction-ability and -selectivity. Benzo-18-crown-6 and its open-ring analog 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene–alkali metal picrate systems

The constants of overall extraction equilibrium ( K ex) and partition ( K D,MLA) for various diluents and aqueous ion-pair formation ( K MLA) of alkali metal (Li–Cs) picrate (MA) 1:1:1 complexes (MLA) with benzo-18-crown-6 (B18C6) and its open-ring analogue 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene (AC·B18C6) were determined at 25 °C, L being B18C6 or AC·B18C6; the distribution constants of AC·B18C6 were measured at 25 °C. The partition behavior of AC·B18C6 and the MLA complexes closely obeys regular solution theory, omitting chloroform; the molar volumes and the solubility parameters of AC·B18C6 and the MLA complexes were determined. The extraction selectivities of AC·B18C6 and B18C6 for the alkali metal picrates increase in the order Li < Na < Cs < K or Rb < or ≈ Rb or K and Li ≪ Na < Cs < Rb < K, respectively. The extraction selectivity of B18C6 for neighboring alkali metal ions in the periodic table is superior to that of AC·B18C6. The macrocyclic effect on the extraction-ability and -selectivity was quantitatively elucidated by the four fundamental equilibrium constants.

Relationship between rice grain amylose and pasting properties for breeding better quality rice varieties

AbstractOne hundred and sixty‐seven rice varieties/laudraces from 23 different rice‐growing countries were used for studying the relationship between the amylose content (AC %) and paste viscosity parameters (RVU) through Pearson correlation. AC and paste viscosity parameters were measured using Auto Analyser and Rapid Visco Analysers respectively. Based on all five RVA pasting properties, i.e. peak viscosity (PV), minimum viscosity (MV), breakdown (BD), final viscosity (FV) and setback (SB), the simple paired t‐test (at P = 0.05) was carried out to identify varieties that showed non‐significant differences (similar) from the check variety, separately for each of the four AC groups, e.g. Waxy rice AC (0–8%, n = 21) –‘IR29’ (Philippines); Low AC (8.1–16%, n = 58) –‘Koshihikari’ (Japan); Intermediate AC (16.1–24%, n = 64) –‘Local Sadri’ (Iran); high AC (&gt;24.1%, n = 24) –‘Kasalath’ (India). Significant variation among the rice varieties for AC and pasting properties were observed. Means of the AC and the viscosity parameters including PV, MV, BD, FV and SB were 15.8, 416.1, 180.3, 235.8, 380.9 and 200.6 RVU respectively. Significant correlations existed between AC and paste viscosity parameters at AC group level. The paste viscosity parameters, i.e. PV, BD and SB are important within an AC group as far as cooking quality is concerned. In the low AC group, ‘Koshihikari’ (check) was most preferred by Japanese consumers, which was used for identifying 16 varieties that showed non‐significant differences for pasting properties with it. Some of the important Japanese varieties were ‘Todorokiwase’, ‘Owarihatamochi’, ‘Sasanishiki’, ‘Reimei’ and ‘Kinuhikari’. These varieties had good cooking quality with low AC, high PV and BD with low SB. In contrast, the Iranian cultivar ‘Local Sadri’ with good cooking quality had intermediate levels of AC and SB while recording high PV and BD. The varietal diversity for pasting properties available within each AC group may allow the breeder to make effective selections for improving the cooking quality according to consumer choice.

Channel hot-electron degradation on 60-nm HfO/sub 2/-gated nMOSFET DC and RF performances

Channel hot-carrier-induced dc and RF performance degradations in 60-nm high-k nMOSFETs are examined experimentally. RF performances such as the cutoff frequency, noise figure, linearity, and flicker noise of high-k MOSFETs show significant vulnerability to the hot-electron effect. Analytical equations for normalized RF degradations relating to the device dc and ac parameters are derived. Good agreement between the analytical predictions and experimental data is obtained. The accuracy of the model equations suggests fast and effective evaluation of noise figure and linearity degradations using simple dc and ac parameters directly.