Diurnal variations of individual organic compound constituents of ultrafine and accumulation mode particulate matter in the Los Angeles Basin

Individual organic compounds can be used as tracers for primary sources of ambient particulate matter (PM) in chemical mass balance receptor models. Previous work has examined PM2.5 only and usually over long sampling periods encompassing entire days or longer. In this study, a high-flow-rate, low-pressure-drop ultrafine particle separator was deployed to collect sufficient mass for organic speciation of ultrafine and accumulation mode aerosol on a diurnal basis. Particles between 0.18 and 2.5 microm in diameter were collected on a quartz-fiber impaction substrate, and ultrafine particles below 0.18 microm were collected downstream on a high-volume filter. Four daily time period samples (morning, midday, evening, and overnight) were sampled over five weekdays to form a weekly average composite for each diurnal period. Sampling was conducted at two sites over two seasons; summer (August) and winter (January) samples were collected at both an urban site near downtown Los Angeles (University of Southern California) and a downwind, inland site in Riverside, CA. Hopanes, used as organic markers for vehicular emissions, were found to exist primarily in the ultrafine mode. Levoglucosan, an indicator of wood combustion, was quantified in both size ranges, but more was present in the accumulation mode particles. An indicator of photochemical secondary organic aerosol formation, 1,2-benzenedicarboxylic acid, was found primarily in the accumulation mode and varied with site, season, and time of day as one would expect for a photochemical product. The atmospheric variations of particulate cholesterol and other organic acids were also considered. By examining the diurnal variation, size-fractionation, and intercorrelations of individual organic compounds, the sources and atmospheric fate of these tracers can be better understood and their utility as molecular markers can be assessed.     

Photomodulated thermoreflectance investigation of semiconducting implanted wafers

The non contact character of the photothermal technique makes it particularly attractive for the nondestructive evaluation of implanted materials. Photomodulated thermoreflectance (PMTR) can detect local variation in the reflectivity of the material caused by the modulated excursions of the surface temperature and plasma surface concentration. These measurements allow the estimation of certain characteristics such as local electronic, optical, and thermal parameters. In the case of implanted semiconductors, PMTR provides an indication of local degree of damage.     

Removal of total phenols from olive-mill wastewater using an agricultural by-product, olive pomace

The purpose of this study was to investigate the sorption of total phenols, which are contained in olive-mill wastewater (OMWW), on solid by-products of olive pomace processing mills. Preliminary batch experiments were conducted using three different types of olive pomace, dried olive pomace (OP-1), dried and solvent extracted olive pomace (OP-2) and dried, solvent extracted and incompletely combusted olive pomace (OP-3). According to the results, OP-3 showed high performance for total phenols sorption and stability. For sorbent concentration of 10 g L⁻¹ and sorbate concentration of 50 mg L⁻¹, more than 40% of initial total phenols concentration was removed. Sorption kinetics was well described by the pseudo-second order rate model (R² > 0.99). Total phenols removal efficiency was improved by increasing sorbent concentration and solution's pH or decreasing particle size of the sorbent material. The Langmuir and Freundlich isotherms sufficiently described OP-3 sorption capacity for the concentration range studied (50–500 mg L⁻¹). Fixed bed sorption experiments showed that lower flow rates and smaller particle size of sorbent resulted in longer column exhaustion time and higher initial removal efficiency. Experiments with thermally or chemically regenerated OP-3 showed that sorption capacity deteriorated after regeneration.     

Adsorption dynamics and interfacial properties of thiol-based cobalt terpyridine monolayers

Spontaneously adsorbed monolayers of [Co(ttp-CH₂-SH)₂](PF₆)₂ have been formed on platinum microelectrodes by exposure to micromolar solutions of the complex in 0.1 M TBABF₄ in acetonitrile, ttp-CH₂-SH is 4′-(p-(thiolmethyl)-phenyl)-2,2′:6′,2″-terpyridine. Resonance Raman spectroscopy on roughened polycrystalline platinum macro electrodes show that the molecule undergoes adsorption through the sulphur atom onto the platinum surface. The monolayers show reversible and well defined cyclic voltammetry when switched between Co²⁺ and Co³⁺ forms, with a peak to peak splitting of 0.040 ± 0.005 V up to 200 V s⁻¹ and an FWHM of 0.138 ± 0.010 V. Adsorption is irreversible leading to the maximum surface coverage, 6.3 ± 0.3 × 10⁻¹¹ mol cm⁻² for 2.5 ≤ [Co(ttp-CH₂-SH)₂] ≤ 10 μM. The rate of monolayer formation appears to be controlled not by mass transport or interfacial binding but by surface diffusion of the complex. The surface diffusion coefficient is 5.5 ± 1.1 × 10⁻⁷ cm² s⁻¹ indicating that prior to formation of an equilibrated monolayer, the adsorbates have significant mobility on the surface. The electron transfer process across the monolayer-electrode interface has been probed by high speed chronoamperometry and the standard heterogeneous electron transfer rate constant, k°, is approximately 3.06 ± 0.03 × 10⁴ s⁻¹. The reorganization energy is at least 18.5 kJ mol⁻¹.     

A Gaussian sampling heuristic estimation model for developing synthetic trip sets

In this paper, we develop a heuristic model based on Gaussian processes to determine synthetic sets of trips in urban networks, considering only supply-related information. This is an alternative to the benchmark method used in the literature, which consists of repeating several trials of Monte Carlo simulations and therefore requiring a complex calibration task and large computational resources. The developed heuristic model explicitly leverages the probabilistic nature of Gaussian processes and exploits their properties to iteratively select origin–destination (od) pairs of nodes in the city network. The model then determines the shortest trip in distance for the selected od pairs and appends it to the synthetic set. We discuss the implementation and performance of both the benchmark method and the developed heuristic model on two city networks. We show that the presented model is more robust and computationally efficient than the benchmark method. This is evidenced by its ability to determine synthetic sets with much smaller sizes, naturally reducing the computational burden, when compared to the benchmark method. We also discuss how the choice of the kernel function and calibration of the hyperparameters influence the performance of the presented heuristic model.     

A simple and precise method for the routine determination of platelet-activating factor in blood and urine

A simple and precise method is described for the measurement of platelet-activating factor (PAF) in blood and urine. The method involves the isolation of PAF from blood samples by two successive steps. In the first step, blood proteins are precipitated with ethanol and the “free” PAF, i.e. the PAF which is extractable with ethanol, is recovered. In the second step, “bound” PAF, i.e., PAF not extractable with ethanol, is extracted from the protein precipitate with chloroform/methanol/water. The extraction of PAF from urine samples requires only the ethanol extraction step. “Free” and “bound” PAF are then each fractionated by silicic acid column chromatography, and the methanol/water eluent containing PAF is then further fractionated by high-performance liquid chromatography using an isocratic solvent system of acetonitrile/methanol/water. PAF is then quantitated by measuring its ability to induce platelet aggregation in an aggregometer. Application of the method to blood and urine samples from twenty-three healthy volunteers revealed PAF levels in blood of 140–480 pg/mL (630–254.4 pg “free” PAF/mL and 64–225.6 pg “bound” PAF/mL), and of 1.2–4.0 pg PAF/mL in urine. The method overcomes various technical problems and was shown to be very precise. It should prove useful for monitoring PAF levels in various disease conditions.     

Multilevel modelling for the regional effect of enforcement on road accidents

This paper investigates the effect of the intensification of Police enforcement on the number of road accidents at national and regional level in Greece, focusing on one of the most important road safety violations: drinking-and-driving. Multilevel negative binomial models are developed to describe the effect of the intensification of alcohol enforcement on the reduction of road accidents in different regions of Greece. Moreover, two approaches are explored as far as regional clustering is concerned: the first one concerns an ad hoc geographical clustering and the second one is based on the results of mathematical cluster analysis through demographic, transport and road safety characteristics. Results indicate that there are significant spatial dependences among road accidents and enforcement. Additionally, it is shown that these dependences are more efficiently interpreted when regions are determined on the basis of qualitative similarities than on the basis of geographical adjacency.     

Pecunia olet: The role of incidental disgust in the ultimatum game.

We address the role of the incidental emotion of disgust in the Ultimatum Game. Participants had to choose whether or not to accept a ? offer from a ?0 pot made by another participant; 120 were in a room where a disgusting smell was released and 120 were in a room with no particular smell. Acceptance rates were higher in the room with the disgusting smell. The effect was mainly carried by the male participants who also reported more disgust with the disgusting smell and judged the offer as less unfair than females. We propose a spontaneous discounting explanation. Acceptance rates were higher in the room with the disgusting smell because participants misattributed the disgust induced by the offer to the ambient disgusting smell. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A structure-function-control paradigm for knowledge-based modeling and design of manufacturing workcells

This paper discusses the integration of structural, functional and control knowledge in manufacturing workcell modeling, simulation and design. After an overview of applications of semantic and object-oriented data models in the manufacturing domain, issues relating to the control synthesis for manufacturing workcells are presented. In particular, a data model encompassing functional and control features, along with application domain structural knowledge, is developed. This model assists in explicitly representing the control aspects of engineering design within an object-oriented database and supports a task-level, functionality-driven, manufacturing workcell design. Since manufacturing workcells consist of a number of elements interacting in a complex manner, workcell control design is one of the most difficult steps in the workcell design procedure. Message passage, commonly used in object-oriented databases, provides no explicit modeling of the database behavior. Hence, it can not serve as a tool for the design of system control. On the other hand, Petrinets (PN) have proven successful in describing complex interaction among active agents. This paper will explore the incorporation of Petri nets as a basis for describing application control knowledge within a structure-function-control data model.     

Variation of the physicochemical properties diesel-biodiesel blends – range 0–100%

Recently biodiesel has become more attractive because it is made from renewable resources. In this study we demonstrate how the proportion of diesel/biodiesel blends determines the qualitative parameters and energy efficiency of the final product. The use of biodiesel in blends with conventional diesel is becoming more and more valuable, based on European directive for use up to 20% biodiesel by 2020. We came to the conclusion that mixtures up 30% Biodiesel gives product within diesel specification limits which is suitable for commercial use. This methodology can be a manual for the production line of mixtures for commercial use.