Coastal water quality impact of stormwater runoff from an urban watershed in southern California

Field studies were conducted to assess the coastal water quality impact of stormwater runoff from the Santa Ana River, which drains a large urban watershed located in southern California. Stormwater runoff from the river leads to very poor surf zone water quality, with fecal indicator bacteria concentrations exceeding California ocean bathing water standards by up to 500%. However, cross-shore currents (e.g., rip cells) dilute contaminated surf zone water with cleaner water from offshore, such that surf zone contamination is generally confined to < 5 km around the river outlet. Offshore of the surf zone, stormwater runoff ejected from the mouth of the river spreads out over a very large area, in some cases exceeding 100 km2 on the basis of satellite observations. Fecal indicator bacteria concentrations in these large stormwater plumes generally do not exceed California ocean bathing water standards, even in cases where offshore samples test positive for human pathogenic viruses (human adenoviruses and enteroviruses) and fecal indicator viruses (F+ coliphage). Multiple lines of evidence indicate that bacteria and viruses in the offshore stormwater plumes are either associated with relatively small particles (< 53 microm) or not particle-associated. Collectively, these results demonstrate that stormwater runoff from the Santa Ana River negatively impacts coastal water quality, both in the surf zone and offshore. However, the extent of this impact, and its human health significance, is influenced by numerous factors, including prevailing ocean currents, within-plume processing of particles and pathogens, and the timing, magnitude, and nature of runoff discharged from river outlets over the course of a storm.     

Quantitative label-free characterization of avidin-biotin assemblies on silanized glass

In this study, a time-of-flight secondary ion mass spectrometer TOF-SIMS, operating in the event-by-event bombardment/detection mode was used to characterize avidin-biotin assemblies on silane-modified glass substrates. SIMS was used to analyze several variants of the biointerface, including avidin physically adsorbed on a monofunctional acryl silane surface and covalently attached on monofunctional (amine terminated) and bifunctional (amine and acryl terminated) silanes. The goal of these studies was to determine density of avidin and biotin layers chemically or physically adsorbed on silanized glass substrate. An individual impact of a C(60) projectile used in this study creates a hemispherical crater (～10 nm in diameter) and emits large numbers of secondary ions from the same nanovolume. Thus, a single impact enables one to unfold distinct secondary ions that span the thickness of the assembled film. This method was used to monitor the presence of glass, silane, and protein ions and to estimate the thickness and density of the avidin layer. In addition, we employed the double coincidence mass spectrometry approach to identify ions coemitted from a specific stratum of the biointerface. This approach was used to determine density of biotin and avidin immobilization while eliminating interferences from isobaric ions that originated from other constituents on the surface. Overall, novel TOF-SIMS quantitative approaches employed here were useful for examining complex biointerfaces and determining both lateral and in depth composition of the film.     

Ellipsometric studies of microscopic surface roughness of CdS thin films

Analysis of changes in surface roughness of CdS thin films with preparation temperature was carried out using variable angle spectroscopic ellipsometry (VASE). The films studied were prepared by spray pyrolysis technique, in the substrate temperature range 200–360°C. The VASE measurements were carried out in the visible region below the band gap (E _g=2·4eV) of CdS so as to reduce absorption by the film. The thickness of the films was in the range 500–600 nm. Bruggeman’s effective medium theory was used for analysis of the surface roughness of the film. The roughness of the film had a high value (∼ 65 nm) for films prepared at low temperature (200°C) and decreased with increase in substrate temperature. This reached minimum value (∼ 27 nm) in the temperature range 280–300°C. Thereafter roughness increased slowly with temperature. The growth rate of the films was calculated for different temperature ranges. It was found that the deposition rate decreases with the increase in substrate temperature and have an optimum value at 300°C. Above this temperature deposition rate decreased sharply. The scanning electron micrograph (SEM) of the film also showed that the film prepared at 280–300°C had very smooth surface texture.     

Equilibrium swelling and solvation studies on crosslinked polyacrylamides

Polyacrylamide (PA) crosslinked with four different crosslinking agents, triethyleneglycol dimethacrylate (TEGDMA), N,N′‐methylene bisacrylamide (NNMBA), hexanediol dimethacrylate (HDDMA) and divinylbenzene (DVB), with mole percents ranging from 5 to 20, was prepared by solution polymerization and subjected to swelling and solvation studies. Solubility parameters and cohesive energy density were determined from swelling studies. Molecular weight between crosslinks for these systems were determined by Flory–Rehner analysis. There is a discontinuous volume change for 10% NNMBA and HDDMA crosslinked PA, 15% TEGDMA crosslinked PA and 10 and 15% DVB crosslinked PA in solvent mixtures of acetic acid and water due to phase change occurring at this stage. The hydrogels exhibit inhomogeneous crosslink distribution due to multiple crosslinking, cyclization and network irregularity owing from arising from entanglements. As the percentage of crosslinking increases, crosslinks become more homogeneous due to a decrease in entanglements. Copyright © 2004 Society of Chemical Industry     

Optimising resource portfolio planning for capital-intensive industries under process-technology progress

This paper addresses the problem of resource portfolio planning of firms in high-tech, capital-intensive manufacturing industries. In light of the strategic importance of resource portfolio planning in these industries, we offer an alternative approach to modelling capacity planning and allocation problems that improves the deficiencies of prior models in dealing with three salient features of these industries, i.e. fast technological obsolescence, volatile market demand, and high capital expenditure. This paper first discusses the characteristics of resource portfolio planning problems including capacity adjustment and allocation. Next, we propose a new mathematical programming formulation that simultaneously optimises capacity planning and task assignment. For solution efficiency, a constraint-satisfied genetic algorithm (CSGA) is developed to solve the proposed mathematical programming problem on a real-time basis. The proposed modelling scheme is employed in the context of a semiconductor testing facility. Experimental results show that our approach can solve the resource portfolio planning problem more efficiently than a conventional optimisation solver. The overall contribution is an analytical tool that can be employed by decision makers responding to the dynamic technological progress and new product introduction at the strategic resource planning level.     

Analog and RF performance of doping-less tunnel FETs with $$\hbox {Si}_{0.55} \hbox {Ge}_{0.45}$$ source

This paper reports studies of a doping-less tunnel field-effect transistor (TFET) with a \(\hbox {Si}_{0.55} \hbox {Ge}_{0.45}\) source structure aimed at improving the performance of charge-plasma-based doping-less TFETs. The proposed device achieves an improved ON-state current (\(I_{{\mathrm{ON}}} \sim {4.88} \times {10}^{-5}\,{\mathrm{A}}/\upmu {\mathrm{m}}\)), an \(I_\mathrm{ON}/I_\mathrm{OFF}\) ratio of \({6.91} \times {10}^{12}\), an average subthreshold slope (\(\hbox {AV-SS}\)) of \(\sim \) \({64.79}\,{\mathrm{mV/dec}}\), and a point subthreshold slope (SS) of 14.95 mV/dec. This paper compares the analog and radio of frequency (RF) parameters of this device with those of a conventional doping-less TFET (DLTFET), including the transconductance (\(g_{{\mathrm{m}}}\)), transconductance-to-drain-current ratio \((g_\mathrm{m}/I_\mathrm{D})\), output conductance \((g_\mathrm{d})\), intrinsic gain (\(A_{{\mathrm{V}}}\)), early voltage (\(V_{{\mathrm{EA}}}\)), total gate capacitance (\( C_{{\mathrm{gg}}}\)), and unity-gain frequency (\(f_{{\mathrm{T}}}\)). Based on the simulated results, the \(\hbox {Si}_{0.55}\hbox {Ge}_{0.45}\)-source DLTFET is found to offer superior analog as well as RF performance.     

Analog performance investigation of dual electrode based doping-less tunnel FET

In this paper, we have proposed a device and named it dual electrode doping-less TFET (DEDLTFET), in which electrodes on top and bottom of source and drain are considered to enhance the ON state current and Analog performances. The charge plasma technique is used to generate electron’s and hole’s clouding depending upon their respective work functions at top and bottom of source/drain electrode. Band-to-band-tunneling rate is similar on both sides of source-channel junctions, which increases ON state current. The analog performance parameters of DEDLTFET are investigated and using device simulation the demonstrated characteristics are compared with doping-less (DLTFET) and the conventional doped double gate TFET (DGTFET), such as transconductance \((\hbox {g}_\mathrm{m})\), transconductance to drain current ratio \((\hbox {g}_\mathrm{m}/\hbox {I}_\mathrm{D})\), output-conductance (g\(_{d})\), output resistance \((\hbox {r}_\mathrm{d})\), early voltage \((\hbox {V}_\mathrm{EA})\), intrinsic gain \((\hbox {A}_\mathrm{V})\), total gate capacitance \((\hbox {C}_\mathrm{gg})\) and unity gain frequency \((\hbox {f}_\mathrm{T})\). From the simulation results, it is observed that DEDLTFET has significantly improved analog performance as compared to DGTFET and DLTFET.     

Miscibility of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) with high molecular weight poly(lactic acid) blends determined by thermal analysis

An important strategy used in the polymer industry in recent years is blending two bio‐based polymers to attain desirable properties similar to traditional thermoplastics, thus increasing the application potential for bio‐based and bio‐degradable polymers. Miscibility of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with poly(L ‐lactic acid) (PLA) were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Three different grades of commercially available PLAs and one type of PHBV were blended in different ratios of 50/50, 60/40, 70/30, and 80/20 (PHBV/PLA) using a micro‐compounder at 175°C. The DSC and TGA analysis showed the blends were immiscible due to different stereo configuration of PLA polymer and two distinct melting temperatures. However, some compatibility between PHBV and PLA polymers was observed due to decreases in PLA's glass transition temperatures. Additionally, the blends do not show clear separation by SEM analysis, as observed in the thermal analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The effects of MgO and Al2O3 behaviours on softening–melting properties of high basicity sinter

Because the behaviours of MgO and Al₂O₃ during slag formation of high basicity sinter are not clearly understood, the effects of MgO and Al₂O₃ on softening-melting properties are always arguable. In this paper, four kinds of sinter containing different MgO and Al₂O₃ content are investigated. Some observations are obtained. The mechanism of the influence of MgO and Al₂O₃ on softening properties of sinter are different. Al₂O₃ has priority over MgO to enter into slag phase and forms low-melting point phase while MgO remains unslagged state and mainly exists in wustite as FeO–MgO solid solution. When sinter melts, the viscosity of the slag generated from sinter containing high MgO and Al₂O₃ content is low, which could result in low pressure drop. As MgO and Al₂O₃ content increase, the main minerals of residual slag change from 2CaO?SiO₂ to merwinte and melilite. The changes of the minerals in slag phase can well explain the trend of softening-melting characteristic temperatures.