Novel magnetic properties of graphene: Presence of both ferromagnetic and antiferromagnetic features and other aspects

Investigations of the magnetic properties of graphenes prepared by different methods reveal that dominant ferromagnetic interactions coexist along with antiferromagnetic interactions in all the samples. Thus, all the graphene samples exhibit room-temperature magnetic hysteresis. The magnetic properties depend on the number of layers and the sample area, small values of both favoring larger magnetization. Molecular charge-transfer affects the magnetic properties of graphene, interaction with a donor molecule such as tetrathiafulvalene having greater effect than an electron-withdrawing molecule such as tetracyanoethyleneComment: 16 pges, 5 figure

Effect of Dissipation, Thermal Radiation, Radiation Absorption on Convective Heat and Mass Transfer Flow in a Non-Uniformly Heated Vertical Channel

We analyze the effect of thermal radiation on mixed convective heat and mass transfer flow of a viscous, electrically conducting incompressible fluid through a porous medium in a vertical channel bounded by flat walls. A non-uniform temperature is imposed on the walls and the concentration on these walls is taken to be constant. Assuming the slope δ of the boundary temperature to be small, we solve the governing equations by a perturbation technique. The velocity, the temperature, the concentration, the rate of heat and mass transfer has been analyzed for different variations of the governing parameters. The dissipative effects on the flow, heat and mass transfer are clearly brought out. Keywords: Non-uniform temperature, Porous medium, Thermal Radiation, Radiation Absorption, Dissipatio

Open Loop Fiber Optic Gyroscope : A Technical Note

This technical note describes the design and fabrication of a prototype open-loop interferometric fiber-optic gyroscope (IFOG). The gyro transfer function is transposed from that of a raised-cosine to a sine function using AC modulation, giving maximum sensitivity at rest. Among various signal processing methods, lock-in principle is used to detect the Sagnac phase shift due to rotation. Initial work is done with bulk-optic components. Finally, all-fiber gyroscope is built using laser diode (1300 nm), PINFET detector, fiber couplers and PZT phase modulator. An effort is made to develop compact IFOG with sensing coil diameter of 10 cm and signal processing card of size 10 x 6.5 sq cm. The present set-up is able to detect the direction of rotation at a rotation rate of 5 x 10/sup -4/ radian per second. Presently, the performance of the set-up is limited by the difficulty in achieving complete reciprocity

Effect of Non-Linear Density Variation on Non-Darcy Convective Heat and Mass Transfer with Newtonian Cooling

We investigate the effect of Non-linear density temperature relation on convective heat and mass transfer flow past stretching sheet with Soret and Dufour effects. The Non-linear coupled governing equations have been solved by fourth –order Runge-Kutta method. The velocity, temperature and concentration, skin friction and rate of heat and mass transfer have been discussed for different parametric variations.  We observed that an increase in the density ration γ reduces the velocity, temperature and concentration. Keywords: Heat and Mass transfer, Non-linear temperature relation, Chemical Reaction, Soret and Dufour Effects, Heat sources

Distribution of Capillary Transit Times in Isolated Lungs of Oxygen-Tolerant Rats

Rats pre-exposed to 85% O2 for 5–7 days tolerate the otherwise lethal effects of 100% O2. The objective was to evaluate the effect of rat exposure to 85% O2 for 7 days on lung capillary mean transit time (t¯c) and distribution of capillary transit times (h c(t)). This information is important for subsequent evaluation of the effect of this hyperoxia model on the redox metabolic functions of the pulmonary capillary endothelium. The venous concentration vs. time outflow curves of fluorescein isothiocyanate labeled dextran (FITC-dex), an intravascular indicator, and coenzyme Q1 hydroquinone (CoQ1H2), a compound which rapidly equilibrates between blood and tissue on passage through the pulmonary circulation, were measured following their bolus injection into the pulmonary artery of isolated perfused lungs from rats exposed to room air (normoxic) or 85% O2 for 7 days (hyperoxic). The moments (mean transit time and variance) of the measured FITC-dex and CoQ1H2 outflow curves were determined for each lung, and were then used in a mathematical model [Audi et al. J. Appl. Physiol. 77: 332–351, 1994] to estimate t¯c and the relative dispersion (RDc) of h c(t). Data analysis reveals that exposure to hyperoxia decreases lung t¯c by 42% and increases RDc, a measure h c(t) heterogeneity, by 40%