Facile Fabrication of Sodium Titanate Nanostructures Using Metatitanic Acid ( T

Fluffy sodium titanate nanostructures have been fabricated by a simple hydrothermal method with metatitanic acid as precursor. The obtained nanostructures exhibit as the aggregation of nanosheets, and the surface area of the nanostructure is about 110.59 m2/g. Such nanoarchitecture indicates high adsorption capacity to some metal ions, such as Cd2+, and the maximum adsorption capacity has been estimated to be 255.18 mg/g. The possible reasons that are responsible after its high adsorption ability, have been ascribed to the tiny structure, the ion-exchange ability and the large surface area of the sodium titanate nanostructures. And this may greatly enlarge its application potential as an adsorbent

The strong influence of substrate conductivity on droplet evaporation

We report the results of physical experiments that demonstrate the strong influence of the thermal conductivity of the substrate on the evaporation of a pinned droplet. We show that this behaviour can be captured by a mathematical model including the variation of the saturation concentration with temperature, and hence coupling the problems for the vapour concentration in the atmosphere and the temperature in the liquid and the substrate. Furthermore, we show that including two ad hoc improvements to the model, namely a Newton's law of cooling on the unwetted surface of the substrate and the buoyancy of water vapour in the atmosphere, give excellent quantitative agreement for all of the combinations of liquid and substrate considered

Measurement of Interphase Forces based on Dual-modality ERT/DP Sensor in Horizontal Two-phase Flow Gas-water

In order to better understand the mechanisms of two-phase flow and the prevailing flow regimes in horizontal pipelines, the evaluation of interphase forces is paramount. This study develops a method to quantitatively estimate the interphase force in two-phase gas-water flow in horizontal pipeline. The electrical resistance tomography technology is used to measure the void fraction, while the differential pressure perpendicular to the horizontal pipe is measured in different flow patterns via a Differential Pressure sensor. The inner pipe diameter is 50 mm, the water flow range from 3.26 m3/h to 7.36 m3/h, the gas flowrate range from 1 to 60 l/min, which covered a range of flow patterns, the absolute pressure range from0.07 MPa to 0.12 MPa. The relationship between the differential pressure drop and interphase force is established, and the effects of these forces on the flow are analyzed. Experimental results indicate that the dual-modality measurement system was successfully provided a quantitative evaluation of inter-phase forces in two-phase horizontal gas-water flow

Comprehensive Control of Optical Polarization Anisotropy in Semiconducting Nanowires

The demonstration of strong photoluminescence polarization anisotropy in semiconducting nanowires embodies both technological promise and scientific challenge. Here we present progress on both fronts through the study of the photoluminescence polarization anisotropy of randomly oriented nanowire ensembles in materials without/with crystalline anisotropy, small/wide bandgap, and both III-V/II-VI chemistry (InP/ZnO nanowires, respectively). Comprehensive control of the polarization anisotropy is realized by dielectric matching with conformally deposited Ta2O5 (dielectric ratios of 9.6:4.41 and 4.0:4.41 for InP and ZnO, respectively). After dielectric matching, the polarization anisotropy of the nanowire ensembles is reduced by 86% for InP:Ta2O5 and 84% for ZnO:Ta2O5

Pattern formation during the evaporation of a colloidal nanoliter drop: a numerical and experimental study

An efficient way to precisely pattern particles on solid surfaces is to dispense and evaporate colloidal drops, as for bioassays. The dried deposits often exhibit complex structures exemplified by the coffee ring pattern, where most particles have accumulated at the periphery of the deposit. In this work, the formation of deposits during the drying of nanoliter colloidal drops on a flat substrate is investigated numerically and experimentally. A finite-element numerical model is developed that solves the Navier-Stokes, heat and mass transport equations in a Lagrangian framework. The diffusion of vapor in the atmosphere is solved numerically, providing an exact boundary condition for the evaporative flux at the droplet-air interface. Laplace stresses and thermal Marangoni stresses are accounted for. The particle concentration is tracked by solving a continuum advection-diffusion equation. Wetting line motion and the interaction of the free surface of the drop with the growing deposit are modeled based on criteria on wetting angles. Numerical results for evaporation times and flow field are in very good agreement with published experimental and theoretical results. We also performed transient visualization experiments of water and isopropanol drops loaded with polystyrene microsphere evaporating on respectively glass and polydimethylsiloxane substrates. Measured evaporation times, deposit shape and sizes, and flow fields are in very good agreement with the numerical results. Different flow patterns caused by the competition of Marangoni loops and radial flow are shown to determine the deposit shape to be either a ring-like pattern or a homogeneous bump

An empirical algorithm to seamlessly retrieve the concentration of suspended particulate matter from water color across ocean to turbid river mouths

Abstract(#br)We propose a globally applicable algorithm (GAA SPM ) to seamlessly retrieve the concentration of suspended particulate matter (SPM) ( C SPM ) from remote sensing reflectance ( R rs ( λ )) across ocean to turbid river mouths without any hard-switching in its application. GAA SPM is based on a calibrated relationship between C SPM and a generalized index for SPM ( GI SPM ) from water color. The GI SPM is mainly composed of three R rs ( λ ) ratios (671, 745, and 862 nm over 551 nm, respectively), along with weighting factors assigned to each ratio. The weighting factors are introduced to ensure the progressive application of R rs ( λ ) in the longer wavelengths for increasing C SPM . Calibration of GAA SPM employed data collected from multiple estuarine and coastal regions of Europe, China, Argentina, and the USA with the measured C SPM spanning from 0.2 to 2068.8 mg/L. Inter-comparison with several recalibrated well-known C SPM retrieval algorithms demonstrates that GAA SPM has the best retrieval accuracy over the entire C SPM range with a relative mean absolute difference (rMAD) of 41.3% (N = 437). This averaged uncertainty in GAA SPM -derived C SPM is mostly attributed to the retrievals from less turbid waters where C SPM < 50 mg/L (rMAD = 50%, N = 214). GAA SPM was further applied to the Visible Infrared Imaging Radiometer Suite (VIIRS) measurements over prominent coastal areas and produced reliable C SPM maps along with realistic spatial patterns. In contrast, applications of other C SPM algorithms resulted in less reliable C SPM maps with either unjustified numerical discontinuities in the C SPM spatial distribution or unsatisfactory retrieval accuracy. Therefore, we propose GAA SPM as a preferred algorithm to retrieve C SPM over regions with a wide range of C SPM , such as river plume areas

Stability, local structure and electronic properties of borane radicals on the Si(1 0 0)

Deposition of a thin B layer via decomposition of B2H6 on Si (PureB process) produces B-Si junctions which exhibit unique electronic and optical properties. Here we present the results of our systematic first-principles study of BHn (n = 0–3) radicals on Si(1 0 0)2 × 1:H surfaces, the initial stage of the PureB process. The calculations reveal an unexpectedly high stability of BH2 and BH3 radicals on the surface and a plausible atomic exchange mechanism of surface Si atoms with B atoms from absorbed BHn radicals. The calculations show strong local structural relaxation and reconstructions, as well as strong chemical bonding between the surface Si and the BHn radicals. Electronic structure calculations show various defect states in the energy gap of Si due to the BHn absorption. These results shed light on the initial stages of the complicated PureB process and also rationalize the unusual electronic, optical and electrical properties of the deposited Si surfaces

New Carbon Monoliths for Supercapacitor Electrodes. Looking at the Double Layer

Carbon monoliths are prepared by combining two carbon phases. A major phase is activated anthracite, which provides microporosity and a large surface area. The other phase is a carbonized polymer that provides self-consistency and contributes to densifying the monolith. Different degrees of anthracite activation and different contents of the two phases are investigated. These all-carbon monoliths have surface areas up to 2600 m2 g−1, mechanical strengths up to 6 MPa, electrical conductivities up to 2–4 S cm−1, and densities between 0.4 and 0.7 g cm−3. In sulfuric acid electrolyte, gravimetric capacitances up to 307 F g−1 are achieved. The double-layer capacitances due to the hydronium and bisulfate ions are separately measured, the former being approximately 25% higher than the latter. The size of the two ions electro-adsorbed at the double layer is discussed. The pseudocapacitance associated with the hydronium ion is 10–25% of the total capacitance of this ion. All of the carbon monoliths show high capacitance retention with current density; the retention of the double-layer capacitance is similar for the two types of ions and higher than the retention of the pseudocapacitance associated with the hydronium ion.Financial support through the projects of reference MAT2014-57687-R, GV/FEDER (PROMETEOII/2014/010) and University of Alicante (VIGROB-136) is gratefully acknowledged. G.M.-F. thanks MINECO for a pre-doctoral fellowship

Venturi Wet Gas Flow Modeling Based on Homogeneous and Separated Flow Theory

When Venturi meters are used in wet gas, the measured differential pressure is higher than it would be in gas phases flowing alone. This phenomenon is called over-reading. Eight famous over-reading correlations have been studied by many researchers under low- and high-pressure conditions, the conclusion is separated flow model and homogeneous flow model performing well both under high and low pressures. In this study, a new metering method is presented based on homogeneous and separated flow theory; the acceleration pressure drop and the friction pressure drop of Venturi under two-phase flow conditions are considered in new correlation, and its validity is verified through experiment. For low pressure, a new test program has been implemented in Tianjin University’s low-pressure wet gas loop. For high pressure, the National Engineering Laboratory offered their reports on the web, so the coefficients of the new proposed correlation are fitted with all independent data both under high and low pressures. Finally, the applicability and errors of new correlation are analyzed