Characteristics of Nanoparticles-Based Chemical Sensors

Semiconducting nanoparticle tin oxide-based sensors have been prepared with a pressure load of 4, 6, 8, 10 tons and reinforced with carbon nanofibers (CNF) in SnO2 matrix. The SnO2/CNF sensor’s sensitivity for ethyl alcohol has in-creased by a factor of two, in compared with that of pure SnO2 8-ton pressed sensor with lower response time. These results open the way towards further optimized lower cost CNF nanocomposite sensors as compared with expensive tin oxide/carbon nanotubes sensors.

A new approach to solar flare prediction

All three components of the current density are required to compute the heating rate due to free magnetic energy dissipation.Here we present a first test of a new model developed to determine if the times of increases in the resistive heating rate in active region(AR)photospheres are correlated with the subsequent occurrence of M and X flares in the corona.A data driven,3D,non-force-free magnetohydrodynamic model restricted to the near-photospheric region is used to compute time series of the complete current density and the resistive heating rate per unit volume[Q(t)]in each pixel in neutral line regions(NLRs)of 14 ARs.The model is driven by time series of the magnetic field B measured by the Helioseismic&Magnetic Imager on the Solar Dynamics Observatory(SDO)satellite.Spurious Doppler periods due to SDO orbital motion are filtered out of the time series for B in every AR pixel.For each AR,the cumulative distribution function(CDF)of the values of the NLR area integral Qi(t)of Q(t)is found to be a scale invariant power law distribution essentially identical to the observed CDF for the total energy released in coronal flares.This suggests that coronal flares and the photospheric Qi are correlated,and powered by the same process.The model predicts spikes in Qi with values orders of magnitude above background values.These spikes are driven by spikes in the non-force free component of the current density.The times of these spikes are plausibly correlated with times of subsequent M or X flares a few hours to a few days later.The spikes occur on granulation scales,and may be signatures of heating in horizontal current sheets.It is also found that the times of relatively large values of the rate of change of the NLR unsigned magnetic flux are also plausibly correlated with the times of subsequent M and X flares,and spikes in Qi.

Influence of silane coupling agent on microstructure and properties of CCTO-P(VDF-CTFE)composites

Influence of the coupling agent on microstructure and dielectric properties of ceramic-polymer composites is systematically studied using CaCu_(3)Ti_(4)O_(12)(CCTO)as the filler,trichloro-(1H,1H,2H,2H-perfluorooctyl)-silane(Cl_(3)-silane)as coupling agent,and P(VDF-CTFE)88/12 mol.%copolymer as the matrix.It is demonstrated that Cl_(3)-silane molecules can be attached onto CCTO surface using a simple process.The experimental results show that coating CCTO with Cl_(3)-silane can improve the microstructure uniformity of the composites due to the good wettability between Cl_(3)-silane and P(VDF-CTFE),which also significantly improves the electric breakdown field of the composites.It is found that the composites using CCTO coated with 1.0 wt.%Cl_(3)-silane exhibit a higher dielectric constant with a higher electric breakdown field.For the composites with 15 vol.%CCTO that is coated with 1.0 wt.%Cl_(3)-silane,an electric breakdown field of more than 240 MV/m is obtained with an energy density of more than 4.5 J/cm^(3).It is also experimentally found that the dielectric constant can be used to easily identify the optimized content of coupling agent.

Remote sensing of land use/cover changes in South and Southeast Asian Countries

Land-Use/Cover Changes(LU/CC)are occurring rapidly in South/Southeast Asian(S/SEA)countries,generally associated with population growth,economic development and competing demands for land.In the region,the most common LU/CC changes include urban expansion,agricultural land loss,land abandonment,deforestation,logging,reforestation,agricultural expansion,etc.Specific to South Asia,forest cover has been increasing in countries like India,Nepal,and Bhutan due to sustainable afforestation measures;whereas,large-scale deforestation in Southeast Asian countries is continuing,for example,due to oil palm plantation expansion driven by the international market demand in Malaysia and Indonesia.Small-scale deforestation in most of the Southeast Asian countries is due to slash-and-burn agriculture by indigenous people,driven by poverty and population growth.Logging activities are common in Myanmar and Cambodia.In terms of urbanization,South and Southeast Asian countries contain 23 megacities,each with more than 10 million people.Megacities in these countries started as urban clusters which grow rapidly,merging into conurbations.Rapid urbanization is driving agricultural land loss,and agricultural intensification has been increasing due to less availability of land for growing food crops as,for example,in India,Vietnam,and Thailand.The drivers of LU/CC vary widely in the region and include such factors as land tenure,local economic development,government policies,inappropriate land management,land speculation,improved road networks,etc.Also,variability in the weather,climate,and socioeconomic factors drive LU/CC resulting in disruptions of biogeochemical cycles,radiation and surface energy balance.