Magnetic ordering in Zn substitutedCo1.4Ge0.4Fe1.2O4 spinelsystem

A systematic study of the Co_1.4Ge_0.4Fe_1.2O₄ system by X-ray, magnetization, and AC-susceptibility techniques is presented. The present system exhibits para-ferri-cluster spin glass transition for x⩽0.2, while x⩾0.3 it exhibits only a cluster spin glass transition. The AC susceptibility and DC magnetization data support the cluster spin glass ordering in the system. The system exhibits local spin canting behavior     

A parallel resonant converter with postregulators

A parallel resonant power converter (PRC) with postregulator(s) power synchronized to the primary switching frequency is investigated for discontinuous-conduction mode operation. It is analyzed with a magnetic amplifier, which blocks the rising edge of the secondary voltage, and with a synchronized buck regulator, which blocks part of the trailing edge of the secondary voltage waveform under the steady-state conditions. As a result, it has been shown that magnetic amplifiers are not suitable for resonant mode power converters, since the step change of the load from low to high during the same switching period as the primary makes the operating conditions worse. However, postregulators that block the trailing edge of the secondary voltage waveform do not adversely affect the operating conditions of PRC and work satisfactorily. As an alternative, a PRC with a magnetic postregulator is presented. An offline 150 W 250 kHz PRC is designed with a magnetic postregulator for a personal computer application, and experimental waveforms are included     

MASS TRANSFER FROM FLAT PLATES TO POWER-LAW FLUIDS IN LAMINAR FLOW

Mass transfer from vertical flat plates to water and 0.5 to 1.5% aqueous CMC solutions is measured in the Reynolds number range of 10^{- 2}to 6.0 x 10₃. Blasius analysis has been found to be valid only up to a Reynolds number of 100, below which Graetz-Leveque solution is more appropriate.     

Magnetically textured ferrofluid in a non-magnetic matrix: Magnetic properties

Texturing of two different magnetic fluids were carried out in paraffin wax under the influence of an external magnetic field. The textured samples were characterized using magnetization measurement and a.c. susceptibility techniques. The results are discussed in the light of ratio of anisotropic energy to magnetic and thermal energies.     

Photoelectrochemical and electrochemical behaviour of gold electrode modified with bilayers of polypyrrole and polyaniline

Modification of electrode surfaces with bilayers of organic/inorganic materials is shown to exhibit a variety of functional characteristics. The use of conducting polymers for bilayer construction has recently been explored by various groups. Gold surface has been modified with bilayers of polyaniline and polypyrrole, and the photoelectrochemical and electrochemical characteristics of such bilayer electrodes have been investigated and are reported in this communication.     

Source/drain extension region engineering in nanoscale double gate SOI MOSFETs: Novel design methodology for low-voltage analog applications

The present paper proposes for the first time, a novel design methodology based on the optimization of source/drain extension (SDE) regions to significantly improve the trade-off between intrinsic voltage gain (A_VO) and cut-off frequency (f_T) in nanoscale double gate (DG) devices. Our results show that an optimally designed 25 nm gate length SDE region engineered DG MOSFET operating at drain current of 10 μA/μm, exhibits up to 65% improvement in intrinsic voltage gain and 85% in cut-off frequency over devices designed with abrupt SDE regions. The influence of spacer width, lateral source/drain doping gradient and symmetric as well as asymmetrically designed SDE regions on key analog figures of merit (FOM) such as transconductance (g_m), transconductance-to-current ratio (g_m/I_ds), Early voltage (V_EA), output conductance (g_ds) and gate capacitances are examined in detail. The present work provides new opportunities for realizing future low-voltage/low-power analog circuits with nanoscale SDE engineered DG MOSFETs.     

Efficacy of Plant‐Derived Antimicrobials as Antimicrobial Wash Treatments for Reducing Enterohemorrhagic Escherichia Coli O157:H7 on Apples

This study investigated the efficacy of 3 GRAS‐status, plant‐derived antimicrobials (PDAs), trans‐cinnamaldehyde (TC), carvacrol (CR), and β‐resorcylic acid (BR) applied as an antimicrobial wash for killing Escherichia coli O157:H7 on apples. “Red delicious” apples inoculated with a 5 strain mixture of E. coli O157:H7 were subjected to washing in sterile deionized water containing 0% PDA (control), 0.15% TC, 0.35% TC, 0.15% CR, 0.30% CR, 0.5% BR, or 1% BR for 1, 3, and 5 min at 23 °C in the presence and absence of 1% soil, and surviving pathogen populations on apples were enumerated at each specified time. All PDAs were more effective in reducing E. coli O157:H7 compared to the water wash treatment (P < 0.05) and reduced the pathogen by 4‐ to 5‐log CFU/apple in 5 min. Chlorine (1%) was the most effective treatment reducing the pathogen on apples to undetectable levels in 1 min (P < 0.05). Moreover, the antimicrobial effect of CR and BR was not affected by the presence of soil, whereas the efficacy of TC and BR was decreased in the presence of soil. Further, no bacteria were detected in the wash solution containing CR and BR; however, E. coli O157:H7 was recovered in the control wash water and treatment solutions containing TC and chlorine, in the presence of 1% soil (P < 0.05). Results suggest that the aforementioned PDAs, especially CR and BR could be used effectively to kill E. coli O157:H7 on apples when used as a wash treatment. Studies on the sensory and quality characteristics of apples treated with PDAs are needed before recommending their usage.     

Investigating Temperature Distribution of Two Different Types of Blackbody Sources Using Infrared Pyrometry Techniques

A comparison between two different types of thermal radiation sources maintaining near blackbody conditions has been carried out in the range from 50 to 500 °C. An infrared total radiation pyrometer was used as a transfer standard to measure the temperature of blackbodies. A thorough study of temperature distribution has been carried out for the large surface source in order to characterize the best location over the surface blackbody for temperature determination precisely of the order of better than 0.1 °C. The expanded uncertainty in the estimation of temperature of the radiating source in the above range of measurement was evaluated to be within ±0.24 °C at 50 °C and ±0.88 °C at 500 °C. The blackbody temperature sources found to be suitable for calibration of infrared total radiation pyrometers and thermal imaging devices in the operational range as mentioned above for laboratory use or other industrial and medical applications.     

An optimization based decision support system for integrated planning and scheduling on dedicated freight corridors

Empty wagon redistribution, train formation, routing and scheduling are complex problems for large railways, many of which currently have or are planning dedicated freight railway corridors (DFC). DFC operations due to their unique characteristics require research and new models for better operations planning. The rolling-stock, being expensive assets, need to be utilised in an optimal manner while meeting service quality levels. Motivated by Indian DFC, we present an integer programming formulation of the dynamic problem of empty distribution and train scheduling in DFC and discuss associated modelling issues. By unifying the separate problems into a single and dynamic model, we have developed a framework for more effective rolling stock utilisation. Based on this optimization model, an interactive decision support system is proposed for better decision-making on rolling-stock allocation and train scheduling. Extensive experiments and systematic analyses for a case of Indian DFC highlight the potentialities and effectiveness of the proposed DSS for DFC operations planning and management.     

Sorbitan ester organogels for transdermal delivery of sumatriptan

The partial phase behavior, rheological, and drug release characteristics of an organogel (OG) composed of water, isooctane and sorbitan esters, sorbitan monopalmitate (Span-40) and poly(oxyethylene)sorbitan monostearate (Polysorbate-60) were studied. Phase diagrams showed decreasing areas of optically isotropic organogel region depending on the surfactant ratio, K_w and drug incorporation. The nonbirefringent, clear isotropic solution suggested the reverse micellar/microemulsion nature of the organogel without any molecular ordering. The increase in drug concentration in OGs leads to increase in the viscosity and sol-gel transition temperature (T_g). Fractal dimension (d_f) values calculated for different compositions suggested that the density of the tubular network increases with increasing drug concentration in OGs. The release rate of the drug from OGs was found to be non-Fickian through the dialysis membrane. The permeation rate of sumatriptan from pig skin was 0.231 mg/h/cm² (781.9 nmol/h/cm²). The study indicates potential of OG as a reservoir system for transdermal drug delivery.