Application of EPA unmix and nonparametric wind regression on high time resolution trace elements and speciated mercury in Tampa, Florida aerosol

Intensive ambient air sampling was conducted in Tampa, FL, during October and November of 2002. Fine particulate matter (PM(2.5)) was collected at 30 min resolution using the Semicontinuous Elements in Aerosol Sampler II (SEAS-II) and analyzed off-line for up to 45 trace elements by high-resolution ICPMS (HR-ICPMS). Divalent reactive gaseous mercury and particulate bound mercury were also measured semicontinuously (2 h). Application of the United States Environmental Protection Agency's (EPA) Unmix receptor model on the 30 min resolution trace metals data set identified eight possible sources: residual oil combustion, lead recycling, coal combustion, a Cd-rich source, biomass burning, marine aerosol, general industrial, and coarse dust contamination. The source contribution estimates from EPA Unmix were then run in a nonparametric wind regression (NWR) model, which convincingly identified plausible source origins. When the 30 min ambient concentrations of trace elements were time integrated (2 h) and combined with speciated mercury concentrations, the model identified only four sources, some of which appeared to be merged source profiles that were identified as separate sources by using the 30 min resolution data. This work demonstrates that source signatures that can be captured at 30 min resolution may be lost when sampling for longer durations.     

Structural changes in marinated fillets of gilthead sea bream (Sparus aurata L.) during vacuum storage at refrigerated temperature

Fillets of Sparus aurata were marinated in a mixture of salt (5.5%) and citric acid (48.9 g/kg) for 1 h, then vacuum packed and refrigerated for 1, 5, 16, and 21 d. Structural and ultrastructural parameters were evaluated in 6 specimens per time period. At day 1, the preservative solution appeared among the muscle fibers, thus increasing the interfibrillar spaces; cytoplasmic organelles were swollen and the sarcolemma-endomysium appeared very altered and electron-dense. At 5 to 10 d, the marinade solution had penetrated into the muscle fibers. The subsarcolemmal and intermyofibrillar spaces were dilated and granular lines of electron-dense material appeared among the fibers. From 16 d, broad interfibrillar spaces were occupied by granular material derived from denatured sarcolemma-endomysium and denatured myofibrils. Sarcomeres were already altered from initial stages, mainly at the I-band level. The Z-line also appeared disrupted. Such alterations were more severe from 10 d on, such that most of the sarcomeres showed disintegration of myofilaments.     

Micropower high current‐drive class AB CMOS current‐feedback operational amplifier

A novel CMOS current‐feedback operational amplifier (CFOA) aimed to low‐power applications is proposed. The use of a compact class AB implementation allows high current‐drive capability and simultaneously very low quiescent power consumption. Measurement results of a fabricated prototype show for an inverting configuration a closed‐loop bandwidth of 1 MHz independent of gain setting, and a slew rate of 2V/µs for a load capacitance of 30 pF and a quiescent power consumption of 264µW. Copyright © 2010 John Wiley & Sons, Ltd.     

Greenhouse gas emission mitigation in the Sri Lanka power sector supply side and demand side options

Sri Lanka has had a hydropower dominated electricity generation sector for many years with a gradually decreasing percentage contribution from hydroresources. At the same time, the thermal generation share has been increasing over the years. Therefore, the expected fuel mix in the future in the large scale thermal generation system would be dominated by petroleum products and coal. This will result in a gradual increase in greenhouse gas (GHG) and other environmental emissions in the power sector and, hence, require special attention to possible mitigation measures.

This paper analyses both the supply side and demand side (DSM) options available in the Sri Lanka power sector in mitigating emissions in the sector considering the technical feasibility and potential of such options. Further, the paper examines the carbon abatement costs associated with such supply side and DSM interventions using an integrated resource planning model, which is not used in Sri Lanka at present. The sensitivities of the final generation costs and emissions to different input parameters, such as discount rates, fuel prices and capital costs, are also presented in the paper. It is concluded that while some DSM measures are economically attractive as mitigation measures, all the supply side options have a relatively high cost of mitigation, particularly in the context of GHG emission mitigation. Further it is observed that when compared with the projected price of carbon under different global carbon trading scenarios, these supply side options cannot provide economically beneficial CO₂ mitigation in countries like Sri Lanka.     

Environmentally motivated modeling of hygro-thermally induced stresses in the layered limestone masonry structures: Physical motivation and numerical modeling

In the present paper, environmentally motivated numerical modeling for the limestone layered masonry structures has been investigated involving the continuous hygric state field variable, i.e. relative humidity ??. By taking advantage of the Lin et?al. assumption pertaining to the relative humidity (independency of the relative humidity and temperature) (Lin MW et?al. Build. Environ. 41(5):646?C656, (2006); Khoshbakht M et?al. Finite Elem. Anal. Des. 42(5):414?C429, (2006); Khoshbakht M, Lin MW Meas. Sci. Technol 2989?C2996, (2006); Khoshbakht M Finite Elem. Anal. Des., 45(8?C9):511?C518, (2009)), we have provided a mathematical model involving hygro-thermo-mechanical aspects as well as the water vapor transfer across the porous limestone masonry walls. The numerical study substantiates the impact of hygric effects as the major key point in the thermo-hygro-mechanical degradation and effect of geometry in the real brick-line of mortar assembly. Furthermore, we have obtained the moisture entrapment at the intersection of the lines of mortar through the layered masonry wall by means of the multidisciplinary nonlinear finite element method (NFEM) for variably saturated porous media. The new outlooks and fresh departure in durability and aging have been briefly discussed.     

Exploitation of nano alumina for the chromatographic separation of clinical grade 188Re from 188W: a renaissance of the 188W/188Re generator technology

The (188)W/(188)Re generator using an acidic alumina column for chromatographic separation of (188)Re has remained the most popular procedure world over. The capacity of bulk alumina for taking up tungstate ions is limited (～50 mg W/g) necessitating the use of very high specific activity (188)W (185-370 GBq/g), which can be produced only in very few high flux reactors available in the world. In this context, the use of high-capacity sorbents would not only mitigate the requirement of high specific activity (188)W but also facilitate easy access to (188)Re. A solid state mechanochemical approach to synthesize nanocrystalline γ-Al(2)O(3) possessing very high W-sorption capacity (500 mg W/g) was developed. The structural and other investigations of the material were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer Emmett Teller (BET) surface area analysis, thermogravimetric-differential thermal analysis (TG-DTA), and dynamic light scattering (DLS) techniques. The synthesized material had an average crystallite size of ～5 nm and surface area of 252 ± 10 m(2)/g. Sorption characteristics such as distribution ratios (K(d)), capacity, breakthrough profile, and elution behavior were investigated to ensure quantitative uptake of (188)W and selective elution of (188)Re. A 11.1 GBq (300 mCi) (188)W/(188)Re generator was developed using nanocrystalline γ-Al(2)O(3), and its performance was evaluated for a period of 6 months. The overall yield of (188)Re was >80%, with >99.999% radionuclidic purity and >99% radiochemical purity. The eluted (188)Re possessed appreciably high radioactive concentration and was compatible for the preparation of (188)Re labeled radiopharmaceuticals.     

Imaging polarimetry of the fogbow: polarization characteristics of white rainbows measured in the high Arctic

The knowledge on the optics of fogbows is scarce, and their polarization characteristics have never been measured to our knowledge. To fill this gap we measured the polarization features of 16 fogbows during the Beringia 2005 Arctic polar research expedition by imaging polarimetry in the red, green and blue spectral ranges. We present here the first polarization patterns of the fogbow. In the patterns of the degree of linear polarization p, fogbows and their supernumerary bows are best visible in the red spectral range due to the least dilution of fogbow light by light scattered in air. In the patterns of the angle of polarization α fogbows are practically not discernible because their α-pattern is the same as that of the sky: the direction of polarization is perpendicular to the plane of scattering and is parallel to the arc of the bow, independently of the wavelength. Fogbows and their supernumeraries were best seen in the patterns of the polarized radiance. In these patterns the angular distance δ between the peaks of the primary and the first supernumerary and the angular width σ of the primary bow were determined along different radii from the center of the bow. δ ranged between 6.08° and 13.41°, while σ changed from 5.25° to 19.47°. Certain fogbows were relatively homogeneous, meaning small variations of δ and σ along their bows. Other fogbows were heterogeneous, possessing quite variable δ- and σ-values along their bows. This variability could be a consequence of the characteristics of the high Arctic with open waters within the ice shield resulting in the spatiotemporal change of the droplet size within the fog.     

Integrated resource planning in the power sector and economy-wide changes in environmental emissions

This paper analyzes the roles of key factors (i.e., changes in structure, fuel mix and final demand) on total economy-wide changes in CO₂, SO₂ and NO_x emissions when power sector development follows the integrated resource planning (IRP) approach instead of traditional supply-based electricity planning (TEP). It also considers the rebound effect (RE) of energy efficiency improvements in the demand side and analyzes the sensitivity of the results to variations in the values of the RE. A framework is developed to decompose the total economy-wide change in the emission of a pollutant into four major components, i.e., structural change-, fuel mix- , final demand- and joint-effects. The final demand effect is further decomposed into three categories, i.e., construction of power plants, electricity final demand and final demand related to electricity using equipments. The factor decomposition framework is then applied in the case of the power sector in Indonesia. A key finding in the case of Indonesia is that in the absence of the RE, there would be total economy-wide reductions in CO₂, SO₂ and NO_x emissions of 431, 1.6 and 1.3 million tons respectively during the planning horizon of 2006–2025 under IRP as compared to that under TEP. The decomposition analysis shows that the final demand effect would account for 38% of the total CO₂ emission reduction followed by the structural change effect (35.1%) and fuel mix effect (27.6%) while the joint effect is negligible. The study also shows that economy-wide CO₂ emission reduction due to IRP considering the RE of 45% would be 241 million tons as compared to 333 million tons when the RE is 25%.     

Vision‐Based Hierarchical Recognition for Dismantling Robot Applied to Interior Renewal of Buildings

Abstract: New robotic systems are going to play an essential role in the future dismantling service for renewing office interiors in buildings. In dismantling tasks, robots are expected to be able to find and remove very small parts such as screws and bolts. Such recognition of small parts is difficult for robots. The article describes a vision‐based hierarchical recognition applied to dismantling tasks where large structures are detected at first, thus small parts attached to these structures are detected easier. Regarding the items in the ceiling side, after the dismantling task of the ceiling panels, it is necessary to remove carefully the screws that once held these panels to the light gauge steel (LGS), with the purpose of reusing it. With the pose detection of the large structure (LGS) and considering a robot arm with a stereo camera on its tip, a trajectory near that structure can be computed to detect the small parts, in this case the screws. The large structure is detected by using a process of line detection in 2D and its 3D pose is measured with the stereo camera. During the motion along the structure, the screws are detected by applying a multi‐template matching process to every captured image. Followed by, the Support Vector Machine (SVM), which recognizes those screw candidates with high true positive rate and low false positive one. These rates are improved with a temporal multi‐image integration for tracking the screw candidates. In the experiment, 10 actual screws distributed in 1.1 m along a linear segment on the LGS are successfully recognized with a few false positives and with a final computed 3D position of 2 mm in average. Feasibility of methodology is evaluated by experimentation under different lighting conditions in a realistic environment. Experimental results show that the method works well to be applied in an actual dismantling site.     

Low-temperature spark plasma sintering of NiO nanoparticles

NiO nanoparticles of 20 nm in diameter were spark plasma sintered between 400 °C and 600 °C for 5 and 10 min durations. Application of 100 MPa pressure from room temperature resulted in densities between 75% and 92%. The final grain size was between 26 nm and 68 nm. Lower densities were recorded when 100 MPa was applied at the SPS temperature. Two shrinkage rate maxima of ∼3.4 × 10⁻³ s⁻¹ and ∼2 × 10⁻³ s⁻¹ were observed around 390 ± 10 °C and at the SPS temperature. The two shrinkage rate maxima were related to densification by particle sliding followed by diffusional grain boundary sliding during the heating. The strong effects of the surface and interfacial processes which are active during the SPS were highlighted.