Design,simulation and analysis of RF MEMS capacitive shunt switches with high isolation and low pull-in-voltage

Microsystem Technologies - This paper presents the design a capacitive shunt type RF-MEMS switch with high isolation, high switching speed and low actuation voltage for Ka-band applications. The...     

Investigation of structural,optical, electrical,and magnetic properties of Fe-doped La0.7Sr0.3MnO3 manganites

In this work, the physical properties of nanocrystalline samples of La_0.7Sr_0.3Mn_1−xFe_xO₃ (0.0 ≤ x ≤ 0.20) perovskite manganites synthesized by the reverse micelle (RM) technique were explored in detail. The phase purity, crystal structure, and crystallite size of the samples were determined using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. All the samples had rhombohedral crystal structure and crystallite size increased with increase in Fe content in La_0.7Sr_0.3MnO₃. The scanning electron micrographs (SEMs) exhibited smooth surface morphology and nonuniform shape of the particles. The optical properties studied using UV-visible absorption spectroscopy revealed a decrease in the absorbance and optical band gap with an increase in Fe content in La_0.7Sr_0.3MnO₃ compound. The temperature-dependent resistivity measurements revealed semiconducting nature of x = 0 and 0.1 samples up to the studied temperature range, while a metal-to-insulator transition was observed at higher Fe doping. Magnetic studies revealed weak ferromagnetism in all the samples and a reduction in the maximum magnetization with an increase in Fe content. A close correlation between electrical transport and magnetic properties was observed with the doping of Fe ion in La_0.7Sr_0.3MnO₃ at Mn site. These results advocate strong interactions associated with the double exchange mechanism among Fe³⁺ and Mn³⁺ ions.     

Wild melon: a novel non-edible feedstock for bioenergy

In the present research work, a non-edible oil source Cucumis melo var. agrestis(wild melon) was systematically identified and studied for biodiesel production and its characterization. The extracted oil was 29.1% of total dry seed weight. The free fatty acid value of the oil was found to be 0.64%, and the single-step alkaline transesterification method was used for conversion of fatty acids into their respective methyl esters. The maximum conversion efficiency of fatty acids was obtained at 0.4 wt% Na OH(used as catalyst), 30%(methanol to oil, v/v) methanol amount, 60 ℃ reaction temperature,600-rpm agitation rate and 60-min reaction time. Under these optimal conditions, the conversion efficiency of fatty acid was 92%. However, in the case of KOH as catalyst, the highest conversion(85%) of fatty acids was obtained at 40%methanol to oil ratio, 1.28 wt% KOH, 60 ℃ reaction temperature, 600-rpm agitation rate and 45 min of reaction time.Qualitatively, biodiesel was characterized through Fourier transform infrared spectroscopy(FTIR) and gas chromatography and mass spectroscopy(GC–MS). FTIR results demonstrated a strong peak at 1742 cm~(-1), showing carbonyl groups(C=O)of methyl esters. However, GC–MS results showed the presence of twelve methyl esters comprised of lauric acid, myristic acid, palmitic acid, non-decanoic acid, hexadecanoic acid, octadecadienoic acid and octadecynoic acid. The fuel properties were found to fall within the range recommended by the international biodiesel standard, i.e., American Society of Testing Materials(ASTM): flash point of 91 ℃, density of 0.873 kg/L, viscosity of 5.35 c St, pour point of-13 ℃, cloud point of-10 ℃, total acid number of 0.242 mg KOH/g and sulfur content of 0.0043 wt%. The present work concluded the potential of wild melon seed oil as excellent non-edible source of bioenergy.     

Clinical features of Crimean-Congo haemorrhagic fever in the United Arab Emirates

Crimean-Congo haemorrhagic fever (C-CHF) re-emerged recently in the United Arab Emirates. The clinical outcome of 11 cases of viral haemorrhagic fever patients admitted to hospital between June 1994 and January 1995 is described. Four cases were laboratory confirmed retrospectively as C-CHF, the other patients were diagnosed likely to have the same disease on epidemiological and clinical grounds. In 72.7% of the patients, infection was fatal. Symptoms started 3.5 days before hospitalization. On admission, 81.8% of patients had high fever, 45.5% were vomiting, 63.6% had diarrhoea, 45.5% had haemorrhagic signs, and 18.2% had throat pain. Fatalities occurred 6.8 days after admission. Survivors were hospitalized for 9.3 days. Nosocomial transmission was not observed.     

Growth of ZnSe∶Mn Nanocrystals from Vapour Phase

ZnSe∶Mn nanocrystals were grown by chemical vapour transport method using the matrix of SiO2 aerogels. The cubic structure of the nanocrystals was confirmed by powder X-ray diffraction (XRD) and electron diffraction (ED) studies. The size of the crystals was observed using transmission electron microscope (TEM). The oxidation state of Mn in ZnSe nanocrystal was found using electron spin resonance (ESR) spectrum. The room temperature luminescence measurements show the peaks corresponding to both bandgap of the material and Mn in ZnSe.     

Structural analytical and electrical conduction mechanisms of 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine nanostructure films

The 2,7,12,17-tetra-tert-butyl 5,10,15,20-tetraaza-21,23H-porphine (TTBTP) films were prepared using thermal evaporation technique. The X-ray diffraction (XRD) of the powder showed that TTBTP is polycrystalline with a tetragonal system. Also, the analysis of XRD pattern shows that the TTBTP film of thickness 55 nm has a crystallite size of 24.69 nm which tends to increase with the film thickness. By SEM of 177 nm thick TTBTP film, the topography of the surface is characterized by significant spherical granules. The mean diameter was estimated to be 250 nm for the spherical granules. It was observed that the conductivity increases with increasing the film thickness. Also, the TTBTP is a semiconductor film with thermally activated conduction mechanisms. The current–density–voltage (J–V) characteristics showed Ohmic drives in low voltage, whereas the space charge limited conductivity mechanism is familiar in the high voltage region. The carrier mobility values of TTBTP film are relatively the same for other organic molecules. The 50 nm TTBTP film has a carrier mobility of 1.48?×?10^??9 cm² V^??1 s^??1, which increases with increasing the film thickness.

     

Nutratherapeutics approach against cancer: tomato‐mediated synthesised gold nanoparticles

In this study, an eco‐friendly biosynthesis of stable gold nanoparticles (T‐GNPs) was carried out using different concentrations of tomato juice (nutraceuticals) as a reducing agent and tetrachloroauric acid as a metal precursor to explore their potential application in cancer therapeutics. The synthesis of T‐GNPs was monitored by UV‐visible absorption spectroscopy, which unveiled their formation by exhibiting the typical surface plasmon absorption maxima at 522 nm. The size of T‐GNPs was found to be 10.86 ± 0.6 nm. T‐GNPs were characterised by dynamic light scattering, zeta potential, transmission electron microscopy analysis and Fourier transform infrared spectroscopy. T‐GNPs were further investigated for their anti‐cancer activity against human lung carcinoma cell line (A ₅₄₉) and human cervical cancer cell line wherein the IC₅₀ values were found to be 0.286 and 0.200 mM, respectively. T‐GNPs inhibited the growth of cancer cells by generating ROS and inducing apoptosis. T‐GNPs were found highly effective by virtue of their size, metallic property and capping molecules. Thus, this study opens up the prospects of using nutraceutical (tomato juice) as nutratherapeutic agent (T‐GNPs) against critical diseases like lung cancer and cervical cancer.Inspec keywords: gold, nanoparticles, particle size, cancer, ultraviolet spectra, visible spectra, electrokinetic effects, transmission electron microscopy, Fourier transform infrared spectra, cellular biophysics, spectrochemical analysis, nanomedicine, nanofabricationOther keywords: tomato‐mediated synthesised gold nanoparticles, tomato juice, reducing agent, tetrachloroauric acid, cancer therapeutics, UV‐visible absorption spectroscopy, surface plasmon absorption, dynamic light scattering, zeta potential, transmission electron microscopy analysis, Fourier transform infrared spectroscopy, human lung carcinoma cell line, anticancer activity, human cervical cancer cell line, nutratherapeutic agent, lung cancer, Au     

Elimination of poly-Si gate depletion for sub-65-nm CMOS technologies by excimer laser annealing

Pulsed excimer laser annealing (ELA) is used to reduce the poly-Si gate depletion effect (to <0.1 nm). Low resistivity (0.58 m/spl Omega//spl middot/cm) and high active boron concentration (4/spl times/10/sup 20/ cm/sup -3/) at the gate-oxide interface are achieved while preserving the gate oxide quality and avoiding boron penetration, to meet International Technology Roadmap for Semiconductors requirements for sub-65-nm CMOS technology nodes. ELA is compatible with high-/spl kappa/ dielectric (HfO/sub 2/) and results in significantly lower gate leakage current density as compared with rapid thermal annealing (RTA).     

ALPINE GEOWARPINGS IN THE ZAGROS-TAURUS RANGE: INFLUENCE ON HYDROCARBON GENERATION, MIGRATION AND ACCUMULATION

Megascale monoclinal flexures (‘geowarpings“) with maximum angles of dip ranging from 5° to 13° occur in the Zagros-Taurus range of Iraq and Iran. They face south and SW. with amplitudes of 1.4 to 14.44 kms and axial lengths of 43 to 230 kms. meir axes are parallel to the host mountain range and lie in an en Pchelon configuration, and many are located in the high mountain zone, at or close to the mountain front (i.e. the border with the foothills zone). Neotectonic and stratigraphic evidence suggests the contemporaneous development of these flexures with their host fold-belt during the collision of the Eurasian and Afro-Arabian Plates, which culminated during Upper Miocene-Pliocene time. Differential vertical movements caused greater shortening and thickening in the upwarded regions (10–33%). which lie closer to the plate suture zones, compared to the downwarped regions (3–17%). Development of the geowarpings resulted in circumstances favourable for hydrocarbon generation in downwarped regions. where source rocks were buried sufficiently deeply to produce oil and gas: this then migrated upwards to be trapped in the growing folds, and was sealed by Miocene evaporites. On the other hand, upwarped regions were elevated, and suffered extensive erosion, leading to a reduction in the depth of burial of potential source rocks, and consequently limited possibilities of hydrocarbon generation. Furthermore. the non-deposition and/or erosion of Miocene evaporites in upwarped regions led to the dissipation of considerable volumes of the hydrocarbons which might have been generated. The effect of geowarpings on oil and gas reserves is evident from the distribution of oil- and gasfields. which are almost exclusively located in the downwarped. foothills zone. Geowarpings may be located in the Taurus Range of E Turkey and NE Syria. but a lack of accurate data makes this difficult to investigate. Further studies are needed to develop an efficient exploration plan for oil and gas in that area.     

Dealing with the heat. Selecting a good thermal interface forreliable chip performance

The need for keeping the package at acceptable temperatures has become a critical issue in recent years. To aid in the cooling of their modules, many electronics manufacturers have implemented the use of heat sinks. Thermal interfaces placed between the package and the heat sink to aid in heat dissipation have become increasingly more important and the demands on these interfaces have increased significantly. During the selection of interface materials many factors must be considered. Compliance, conformability, modulus, ease of installation, and cut-through resistance are all important