Bifunctional investigation of ultra-small SnO2 nanoparticle decorated rGO for ozone sensing and supercapacitor applications.

Ultrasmall SnO2 nanoparticles with an average size of 7 nm were synthesized by a hydrothermal method and composited with reduced graphene oxide (rGO) through an ultrasonic assisted solution process. The structural, functional, morphological and compositional properties of synthesised SnO2 and rGO/SnO2 were studied by XRD, FTIR, HRSEM, HRTEM, XPS and Raman analyses. The prepared materials were developed as a film over a PVA/KOH conductive layer coated substrate with varying thickness of 3, 5 and 7 µm to study their ozone sensing characteristics at room temperature. The physico-chemical properties reveal that the fabricated SnO2 and rGO/SnO2 nanocomposite films have a strong interaction with the ozone gas. Among the fabricated composite films rGO/SnO2-S1 film exhibits high ozone sensing response (38%) at room temperature. Additionally, the electrochemical performance of SnO2 and rGO/SnO2 nanocomposites was analysed and the rGO/SnO2 nanocomposite exhibited higher specific capacitance (545 F g-1) than that of pure SnO2 (236 F g-1) at a current density of 1 A g-1 with higher cyclic stability (96%) than that of pure SnO2 (86%) at the current density of 20 A g-1 for a continuous 5000 charge-discharge cycles. Thus, the rGO/SnO2 nanocomposite showed an excellent ozone sensing and energy storage performance.

Zr mesoporous molecular sieves as novel solid acid catalysts in synthesizing nitrile and caprolactam.

Zr mesoporous materials with different Si/Zr ratio were synthesized by the surfactant-templated method involving cetyl trimethyl ammonium bromide (CTAB) as template and tetraethyl ortho silicate (TEOS) as organic source of silicon. The synthesized materials were labeled as SiZrMx (where x is Si/Zr = 10, 20 and 30). The BET analysis showed bimodal distribution of pores in SiZrMx structure. An attempt was made to generate super acidity on SiZrM20 by sulfation using sulfuric acid and ammonium sulfate (wt% = 4, 8 and 12). The NH3-TPD results revealed the presence of strong acidity in sulfated Zr-MCM-41. To understand the nature of acidity in Sulfated Zr-MCM-41, the efficiency of the materials is investigated in dehydration of Oximes. The industrially important materials caprolactam and intermediate nitrile were synthesized from their oximes in liquid phase system. Due to strong acidity in sulfated Zr-MCM-41, fast deactivation was observed during the synthesis of caprolactam but, the catalyst showed 96% nitrile selectivity. The strong acidity and medium strong acidity favoured the formation of nitrile and caprolactam respectively. This study revealed the molecular sieves were effective and eco-friendly solid acid catalysts for synthesizing caprolactam and nitrile.

Gabor spectra for Doppler echocardiography.

Doppler echocardiography on current ultrasonography machines makes use of short-time Fourier spectrograms (STFTs) to display the patterns of blood velocities in the heart chamber. From these sonologists infer the functional parameters, such as valve area, that have pathological significance. After mention of the lacuna in such an STFT display, the Gabor transform and associated Gabor spectrogram evaluation techniques are described. Finally, comparative views of ultrasound machine display with PC-based STFT and Gabor displays for two typical patients are shown, with inferences in support of the proposed Gabor display.