Deposition of Tobacco Smoke Particles in a Low Ventilation Room

Deposition on indoor surfaces is an important removal mechanism for tobacco smoke particles. We report measurements of deposition rates of environmental tobacco smoke particles in a room-size chamber. The deposition rates were determined from the changes in measured concentrations by correcting for the effects of coagulation and ventilation. The airflow turbulent intensity parameter was determined independently by measuring the air velocities in the chamber. Particles with diameters < 0.25 μm coagulate to form larger particles of sizes between 0.25 and 0.5 μm. The effect of coagulation on the particles > 0.5 μm was found to be negligible. Comparison between our measurements and calculations using the theory of Crump and Seinfeld (1981) showed smaller measured deposition rates for particles from 0.1 to 0.3 μm in diameter and greater measured deposition rates for particles larger than 0.6 μm at three mixing intensities. Comparison of Nazaroff and Cass' model (1989a) for natural convection flow showed good agreement with the measurements for particles > 0.1 μm in diameter; however, measured deposition rates exceeded model predictions by a factor of approximately 4 for particles in size range of 0.05–0.1 μm in diameter. These results were used to predict deposition of sidestream smoke particles on interior surfaces. Calculations predict that in 10 hours after smoking one cigarette, 22% of total sidestream particles by mass will deposit on interior surfaces at 0.03 air change per hour (ACH), 6% will deposit at 0.5 ACH, and 3% will deposit at 1 ACH.     

Aerodynamic Focusing of Nanoparticles: II. Numerical Simulation of Particle Motion Through Aerodynamic Lenses

Abstract

We have developed a numerical simulation methodology that is able to accurately characterize the focusing performance of aerodynamic lens systems. The commercial computational fluid dynamics (CFD) software FLUENT was used to simulate the gas flow field. Particle trajectories were tracked using the Lagrangian approach. Brownian motion of nanoparticles was successfully incorporated in our numerical simulations. This simulation tool was then used to evaluate the performance of an aerodynamic lens assembly that was designed to focus 3 nm spherical unit density particles following the guidelines described in Paper I (Wang et al. 2005). Our simulations show that the performance of this lens assembly is close to what is predicted by the design guidelines. The simulations also demonstrate the ability of aerodynamic lenses to focus sub-30 nm spherical unit density particles.     

Electrochemical sensors for the determination of Zn ions based on pendant armed macrocyclic ligand

The construction and performance characteristics of polymeric membrane electrodes based on two newly synthesized macrocyclic ligands 6,7:14,15-Bzo₂-10,11-(4-methylbenzene)-[15]-6,8,12,14-tetraene-9,12-N₂-1,5-O₂ (L₁) and 6,7:14,15-Bzo₂-10,11-(4-methylbenzene)-[15]-6,14-diene-9,12-dimethylacrylate-9,12-N₂-1,5-O₂ (L₂) for the quantification of Zn²⁺ ions are described here. Several membranes having different compositions of PVC, plasticizers, ionic additives and ionophores were fabricated and the best response was observed for the membrane having composition L₂:PVC:TBP:NaTPB in the ratio of 4:37:57:2 (w/w; mg). The response characteristics of the membrane based on L₂ were compared with polymeric membrane electrode (PME) as well as with coated graphite electrode (CGE). The electrode exhibits Nernstian slope for Zn²⁺ ions with limits of detection of 3.3 × 10⁻⁷ mol L⁻¹ for PME and 7.9 × 10⁻⁸ mol L⁻¹ for CGE with response time of 12 s and 10 s for PME and CGE respectively. Furthermore, the electrodes generated constant potentials in the pH range of 3.0–8.0 for PME and 2.5–9.0 for CGE. The practical utility of the CGE has been demonstrated by its usage as an indicator electrode in potentiometric titration of EDTA with Zn²⁺ ion solution. The high selectivity of CGE also permits their use in the determination of Zn²⁺ ions in water, biological, milk and tea samples.     

Role of carboxylic acid functionalized single walled carbon nanotubes in polyamide 6/poly(methyl methacrylate) blend

The nanocomposite of polyamide 6 (PA6)/poly(methyl methacrylate) (PMMA)/carboxylic acid functionalized single walled carbon nanotubes (SWCNTs‐COOH) was prepared in a weight ratio of 49.5/49.5/1 at 230°C by using melt‐mixing method. The PA6/PMMA blend with weight ratio of 50/50 served as reference. The Fourier transform infrared analysis of nanocomposite shows the occurrence of hydrogen‐bonding interactions among PA6, PMMA, and SWCNTs‐COOH. Thermal studies of nanocomposite exhibited higher thermal stability and increased crystallinity of PA6 in nanocomposite compared to the blend. The X‐ray diffraction curve of nanocomposite indicates that the rich α_II phase of PA6 was higher compare to the blend. The scanning electron microscope analysis of nanocomposite confirmed that PMMA exhibited as a uniform dispersion and existed as co‐continuous phase morphology in a continuous phase of PA6 compared to the blend. Furthermore, the obtained results suggest that the incorporation of SWCNTs‐COOH into the PA6/PMMA blend enhances the compatibility as a compatibilizer between the two polymer components. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Activity of Ferric Oxide in Steelmaking Slag

Refining reactions in steelmaking primarily involve oxidation of impurity element(s). The oxidation potential of the slag and the activity of oxygen in the metal (h_O) are the major factors controlling these chemical reactions. In turn, the oxidation potential of the slag is influenced strongly by the equilibrium distribution of oxygen between ferrous and ferric oxides. We recently investigated the activity coefficient of FeO in steelmaking slag and the effect of chemical composition thereon. This work is focused on estimation of the activity coefficient of Fe₂O₃.     

An 80-Tile Sub-100-W TeraFLOPS Processor in 65-nm CMOS

This paper describes an integrated network-on-chip architecture containing 80 tiles arranged as an 8x10 2-D array of floating-point cores and packet-switched routers, both designed to operate at 4 GHz. Each tile has two pipelined single-precision floating-point multiply accumulators (FPMAC) which feature a single-cycle accumulation loop for high throughput. The on-chip 2-D mesh network provides a bisection bandwidth of 2 Terabits/s. The 15-FO4 design employs mesochronous clocking, fine-grained clock gating, dynamic sleep transistors, and body-bias techniques. In a 65-nm eight-metal CMOS process, the 275 mm² custom design contains 100 M transistors. The fully functional first silicon achieves over 1.0 TFLOPS of performance on a range of benchmarks while dissipating 97 W at 4.27 GHz and 1.07 V supply.     

Parametric optimization and performance analysis of a waste heat recovery system using Organic Rankine Cycle

Parametric optimization and performance analysis of a waste heat recovery system based on Organic Rankine Cycle, using R-12, R-123 and R-134a as working fluids for power generation have been studied. The cycles are compared with heat source as waste heat of flue gas at 140 °C and 312 Kg/s/unit mass flow rate at the exhaust of ID fans for 4 × 210 MW, NTPC Ltd. Kahalgaon, India. Optimization of turbine inlet pressure for maximum work and efficiencies of the system along the saturated vapour line and isobaric superheating at different pressures has been carried out for the selected fluids. The results show that R-123 has the maximum work output and efficiencies among all the selected fluids. The Carnot efficiency for R-123 at corrected pressure evaluated under similar conditions is close to the actual efficiency. It can generate 19.09 MW with a mass flow rate of 341.16 Kg/s having a pinch point of 5 °C, First law efficiency of 25.30% and the Second law efficiency of 64.40%. Hence selection of an Organic Rankine Cycle with R-123 as working fluid appears to be a choice system for utilizing low-grade heat sources for power generation.     

Fabrication of novel coated graphite electrodes for the selective nano-level determination of Cd ions in biological and environmental samples

Novel cadmium selective coated graphite electrodes were prepared using three different ionophores N¹, N²-dicyanoethyl-N¹, N²-bis(pyridin-2-ylmethyl)benzene-1, 2-diamine [L₁], N¹, N²-dicyanoethyl-N¹, N²-bis(thiophen-2-ylmethyl) benzene-1, 2-diamine [L₂] and N¹, N²-dicyanoethyl-N¹, N²-bis(furan-2-ylmethyl)benzene-1, 2-diamine [L₃], and their potentiometric characteristics were determined. Membranes having different compositions of poly(vinylchloride) (PVC), the plasticizer o-nitrophenyloctylether (o-NPOE), sodium tetraphenylborate (NaTPB) as an anionic additive and ionophores were coated onto the graphite surface. The potential response measurements showed that the best performance was exhibited by the electrodes with membranes having the composition L₁: o-NPOE:NaTPB:PVC as 4:51:2.5:42.5 (wt.%), L₂: o-NPOE:NaTPB:PVC as 3:52.5:1.5:43 (wt.%) and L₃: o-NPOE:NaTPB:PVC as 7:49:3.5:40.5 (wt.%). These electrodes had the widest working concentration range, Nernstian slope and fast response times of 12 s, 7 s and 17 s for L₁, L₂ and L₃, respectively. The selectivity studies showed that these electrodes have higher selectivity towards Cd²⁺ over a large number of cations and could tolerate up to 20 vol.% non-aqueous impurities. Furthermore, the electrodes generated constant potentials in the pH range 2.0–8.0, with a shelf life of approximately four to six weeks. The high selectivity of these electrodes permits their use in the detection of the Cd²⁺ content in some medicinal plants, soil and industrial wastewater samples. The electrodes could also be used as an indicator electrode in the potentiometric titration of Cd²⁺ with EDTA.     

Study on growth of hollow nanoparticles of alumina

This article addresses the growth of hollow nanocrystalline particles of γ-alumina by the post-oxidation of nano-aluminium particles in air. The nanoparticles of aluminium were synthesized in a DC-transferred arc thermal plasma reactor. The as-synthesized nano-aluminium particles were oxidized, in air, at different temperatures. The as-synthesized parent nano aluminium and their daughter nanoparticles of aluminium oxide were thoroughly characterized with the help of X-ray diffraction analysis, high resolution transmission electron microscopy and thermogravimetric analysis. Two-step oxidation behaviours, unique in nanoparticles, are found to be the main driving force behind the formation of hollow spherical structures. The entire phenomenon is compared with the oxidation behaviour of coarse grain aluminium. The content of γ-alumina, identified by X-ray diffraction, relative to that of unreacted aluminium, has increased almost exponentially with the oxidation temperature in the case of nano aluminium. Similar behaviour is not observed in the case of coarse grain aluminium. The crystalline features of alumina, forming the walls of the hollow sphere, were confirmed by high resolution transmission electron microscopy.