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A single probe-fed novel V slit, stub and slot embedded circular microstrip antenna with resonances in the three bands of UMTS, worldwide interoperability for microwave access (WiMAX) and WLAN is presented. The polarisation is circular in the UMTS band and linear in the other two bands. Asymmetrical V slits in the patch boundary along with an embedded circular slot in the patch centre are employed to introduce the perturbation necessary for circular polarisation. Impedance bandwidths (BWs) of 4.2, 2 and 6.2%, respectively, in the three bands centred at 2, 3.5 and 5.6 GHz are obtained. The axial ratio BW is 2.3% in the UMTS band. Moderate gains of 4.4, 3.5 and 2.8 dBi are obtained in the three bands. There is a patch size reduction of about 48% when compared with the conventional circular patch antenna at a fixed operating frequency. The radiation pattern is directional in the WiMAX band and nearly omnidirectional in the WLAN band.

We report temperature-induced tuning of whispering gallery mode (WGM) laser emission from a Rhodamine-B-doped polymethylmethacrylate hollow optical fiber. Lasing studies on dye-doped hollow fibers with different radii were carried out with optical pumping using a Q-switched Nd:YAG laser. The observed lasing modes were confirmed as WGM emission with a high quality factor of 7.58×10. The diameter-dependent variation in lasing spectra of these hollow fibers was investigated. A tuning range of 0.44 nm with a sensitivity of 0.011  nm/°C was obtained for the lasing modes by varying the temperature from 25°C to 60°C from a dye-doped polymethylmethacrylate hollow fiber of diameter 305 μm.

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Wavelength tuning of whispering gallery lasing modes has been observed from Rhodamine-B-doped polymer fibers under tensile strain. Good quality whispering gallery lasing modes are produced from both solid and hollow fibers by transverse optical pumping. The lasing modes are shifted linearly toward the shorter wavelength side when the fiber is elongated in the axial direction. Compared with solid fiber, the lasing modes of hollow fiber can be tuned over the entire gain spectrum with a tuning range of ∼5  nm. It is found that the tuning of the lasing modes of hollow fiber is reversible.

Printed, circularly polarised, microstrip line fed antenna having asymmetric slotted structure is presented. Two antennas, antenna 1 (A1) and antenna 2 (A2), having the same design but radiating with opposite senses of circular polarisation are fabricated. The geometrical structure consists of uneven combination of elements fixed through parametric variations. The measurements yielded significant impedance bandwidth (IBW) and axial ratio bandwidth (ARBW) for axial ratio (AR) ≤ 3 dB. A1 offered IBW of 9.67 GHz (2.46-12.13 GHz, 132.6%), ARBW of 7 GHz (4-11 GHz, 93.33%) and a peak realised gain of 4.05 dBi. A2 offered IBW of 10.05 GHz (2.55-12.6 GHz, 132.7%), ARBW of 7.3 GHz (3.9-11.2 GHz, 96.7%) and a peak realised gain of 4.1 dBi. This constitutes a wide coverage of over 88% of the ultra-wideband (UWB) spectrum (3.1-10.6 GHz). Omnidirectional radiation patterns and marginal group delays are the other features of these antennas. The proposed design is validated through simulations and experimental investigations.

Summary. The effect of administration of carnitine on the severity of myocardial infarction in rats induced by isoproterenol was studied by following histopathological and biochemical parameters. Carnitine afforded partial protection against myocardial infarction. Serum aspartate amino transferase (GOT) and creative phospho kinase (CPK) values, serum, heart and aortic lipids, serum protein-bound hexose and sialic acid and glyco-saminoglycans in the heart were lower in the carnitine-treated rats. Histopathological examination showed very little necrosis in the carnitine-treated rats when compared to the extensive necrosis in the untreated controls.