Mössbauer Study of Oxygenated Iron-Phthalocyanines,a Precursor of Magnetic Storage Material

⁵⁷Fe transmission Mössbauer spectroscopy and X-ray diffractometry were used to study - and -polymorphs of iron phthalocyanines (FePc) to get information about their oxygenation in connection with controlled pyrolysis of flat layered phthalocyanines initiated by radicals at relatively low temperatures, to form acicular carbide particles encaged in carbon. Mössbauer spectroscopy and XRD revealed that the oxygenation of both - and -polymorphs of FePc was successfully achieved. New Mössbauer spectral components (doublets) appeared upon the oxygenation in both and FePc. This can be attributed to iron microenvironments containing oxygen between the layers of iron phthalocyanines.     

Studies on nessler's reagent and nessler's precipitate part II

The composition of the precipitate formed when the Nessler's reagent is treated with ammonia, is assumed as NH_n-1Hg₂I_n, aq. and has been studied potentiometrically from iodine-hypoiodite-system. It has been observed that the value of n depends on the concentrations of [HgI₄]^-2 and OH^- ions as well as on the amount of ammonia added and it may vary from 1 to 3. The colour of the precipitate deepens from brown to chocolate as the value of n increases.     

Sub- and superluminal propagation of intense pulses in media with saturated and reverse absorption

We develop models for the propagation of intense pulses in solid state media which can have either saturated absorption or reverse absorption. We model subluminal propagation in ruby and superluminal propagation in alexandrite as three and four level systems, respectively, coupled to Maxwell's equations. We present results well beyond the traditional pump-probe approach and explain the experiments of Bigelow et al. [Phys. Rev. Lett. 90, 113903 (2003)]Science 301, 200 (2003)]] on solid state materials.     

Label Free Colorimetric Biosensing Using Nanoparticles

In this review article, we discuss a class of biosensors that exploit the change in the colorimetric properties of noble metal nanoparticles in response to biomolecular binding at their surface. Several sensor fabrication techniques as well as sensor configurations are discussed with an emphasis on their strengths and limitations. We conclude by presenting the future prospects and challenges for the successful transition of this technology from the laboratory to a commercial product.     

Solution phase evolution of AuSe nanoalloys in Triton X-100 under UV-photoactivation

A solution phase UV-irradiation technique has been exploited to produce an AuSe nanoalloy through fusion of preformed Au (photoproduced) and Se (chemically prepared) in a micellar (TX-100) medium.     

Intraoperative contrast-enhanced MR-imaging as predictor of tissue damage during cryoablation of porcine liver

This study evaluate intraoperative Magnetic Resonance Imaging (MRI) as predictor of tissue damage following cryoablation of porcine liver with and without concomitant hepatic vascular inflow occlusion.Inflow occlusion was used during freezing in 6 of 12 pigs included. The volumes of the procedural ice-balls were estimated from MR images. Immediately after thawing contrast (MnDPDP) enhanced MRI was performed to estimate the volume of the cryolesion. Four days after ablation MRI was repeated of the in-vivo and the ex-vivo liver. Photography was performed of the sliced liver specimens to estimate the volumes of the lesions. The intraoperative volume of the cryolesion as shown by contrast enhanced MRI corresponded well to the ice-ball volume for lesions made without vascular occlusion (difference 0.3 +/- 0.9 cm(3), p = 0.239). For lesions made during occlusion the volume of the intraoperative cryolesion was larger than the corresponding ice-ball (difference 7.5 +/- 3.3 cm(3), p = 0.003). The volume of the cryolesions as estimated from histopathology four days after freezing and contrast enhanced MRI immediately after freezing corresponded well for lesions made with (difference -2.6 +/- 4.5 cm(3), p = 0.110) and without vascular occlusion (difference -0.5 +/- 2.3 cm(3), p = 0.695).Intraoperative MnDPDP-enhanced MRI of the cryolesion is predictive of the tissue damage induced during cryoablation of porcine liver. The procedural ice-ball is not, if induced during inflow occlusion.     

Accelerated Bergman cyclization of porphyrinic-enediynes

The Bergman cyclization of simple diethynylporphyrinic-enediynes exhibits a double activation barrier to the formation of Bergman cyclized product. Addition of H-atom acceptor accelerates the formation of the picenoporphyrin, indicating that the second barrier is rate limiting.