HYDROCARBON LOADS FROM STREET CLEANING PRACTICES: COMPARISON WITH DRY AND WET WEATHER FLOWS IN A PARISIAN COMBINED SEWER SYSTEM

Abstract

So far, little attention has been given to the effect of the street cleaning waters (SCW) load on the sewer systems during dry-weather periods. However, the knowledge of this pollution is needed to better understand the contribution of SCW to dry weather flow (DWF) pollution within combined sewers. Therefore, hydrocarbon loads conveyed by SCW were analyzed for two different sites of the Paris agglomeration. Median n-alkane, Unresolved Complex Mixture (UCM) and Polycyclic Aromatic Hydrocarbon (PAH) concentrations have been estimated at 19, 628 and 1.4 μ g · l^{? 1}for the Marais catchment (or 4th district), and at 8, 249, and 2.1 μ g · l^{? 1}for the 13th district, respectively. The observed contamination was mainly attributed to road traffic. Moreover, a comparison between SCW and street runoff showed that street cleaning removes a higher PAH stock than street runoff. In addition, SCW hydrocarbon fluxes evaluated at 5.4, 178 and 0.4 g · d^{? 1}for n-alkanes, UCM and PAH, respectively, were compared to the hydrocarbon fluxes of the DWF pollutant load at the combined sewer outlet of the Marais catchment. Hydrocarbon loads conveyed by SCW into Paris combined sewers appeared to be a minor source of DWF pollution for n-alkane and UCM, but represented a significant source for PAHs.     

How to Attain Ultralow Interfacial Tension and Three-Phase Behavior with Surfactant Formulation for Enhanced Oil Recovery: A Review. Part 1. Optimum Formulation for Simple Surfactant–Oil–Water Ternary Systems

Enhanced recovery of crude oil by surfactant flooding requires the attainment of an ultralow interfacial tension. Since Winsor’s work in the 1950s it has been known that a minimum interfacial tension and a concomitant three-phase behavior of a surfactant–oil–water system occurs when the interactions of the surfactant and the oil and water phases are exactly equal. It has been known since the 1970s that these conditions are attained when a linear correlation is satisfied between the formulation variables, which are characteristic parameters of the substances as well as the temperature. This first part of our review on how to attain ultralow interfacial tension for enhanced oil recovery shows how formulation scan techniques using these correlations are used to determine an optimum formulation and to characterize unknown surfactants and oils. The physicochemical significance of the original empirical correlation is reported as the surfactant affinity difference or hydrophilic–lipophilic deviation model. We report the range of accurate validity of, and how to test, this simple model with four variables.     

Substantially Improving Device Performance of All‐Inorganic Perovskite‐Based Phototransistors via Indium Tin Oxide Nanowire Incorporation

All‐inorganic halide perovskites (IHPs) have attracted enormous attention due to their intrinsically high optical absorption coefficient and superior ambient stabilities. However, the photosensitivity of IHP‐based photodetectors is still restricted by their poor conductivities. Here, a facile design of hybrid phototransistors based on the CsPbBr₃ thin film and indium tin oxide (ITO) nanowires (NWs) integrated into a InGaZnO channel in order to achieve both high photoresponsivity and fast response is reported. The metallic ITO NWs are employed as electron pumps and expressways to efficiently extract photocarriers from CsPbBr₃ and inject electrons into InGaZnO. The obtained device exhibits the outstanding responsivity of 4.9 × 10⁶ A W^?1, which is about 100‐fold better than the previous best results of CsPbBr₃‐based photodetectors, together with the fast response (0.45/0.55 s), long‐term stability (200 h in ambient), and excellent mechanical flexibility. By operating the phototransistor in the depletion regime, an ultrahigh specific detectivity up to 7.6 × 10¹³ Jones is achieved. More importantly, the optimized spin‐coating manufacturing process is highly beneficial for achieving uniform InGaZnO‐ITO/perovskite hybrid films for high‐performance flexible detector arrays. All these results can not only indicate the potential of these hybrid phototransistors but also provide a valuable insight into the design of hybrid material systems for high‐performance photodetection.     

Recovery rheology via rheo-SANS: Application to step strains under out-of-equilibrium conditions

Stress relaxation from a step strain test provides important information about constituent dynamics, but if a material has experienced a complex shear history, the underlying physics is not straightforward to access. We use recovery rheology and rheo-small-angle neutron scattering to probe the nonlinear dynamics of an entangled wormlike micelle solution by applying step strains after complex shear histories enforced by large-amplitude oscillatory shear (LAOS) flow. We show that a universal relaxation modulus can be obtained from step strain tests with complex shear histories, as long as the modulus is defined in terms of the recoverable strain. The shear and normal stresses, as well as the alignment of micellar Kuhn segments, are shown to be positively correlated with the recoverable strain. We identify re-entanglement of polymeric chains after cessation of LAOS and show that this process occurs over the same timescales as linear-regime stress relaxation. This work, therefore, lays the foundation of how to accurately probe out-of-equilibrium rheology in a consistent manner.     

An evaluation of two hypotheses concerning the dynamics of cognitive impulsivity: Anxiety-over-errors or anxiety-over-competence?

To test the appropriateness of the anxiety-over-errors and the anxiety-over-competence hypotheses in explaining reflective and impulsive behavior, 85 8–11 yr olds were classified as reflective or impulsive on the basis of their performance on 1 form of the Matching Familiar Figures Test (MFFT). Half of each cognitive style group was randomly assigned to a failure or control group. Ss in the failure group were given failure feedback concerning their performance on the 1st 10 items of an alternate form of the MFFT and were then tested on the 2nd 10 items. Control Ss were given a short rest period between the 2 10-item test administrations. All Ss rated their expectancy of success and completed the Test Anxiety Scale for Children. Teacher ratings of the children's reflection–impulsivity, confidence, and concern over errors were also obtained. Results support the anxiety-over-errors hypothesis: The impulsives in the failure group showed a significant decrease in errors from pre- to posttest, whereas controls did not differ in this respect. The reflectives in the failure group did not differ from those in the control group in their pre–post error rates. MFFT performance measures were significantly correlated with teacher ratings of concern over errors but not with confidence ratings. It is concluded that impulsive behavior may stem from a lack of motivation to perform well. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive solutions for a system of higher-order multi-point boundary value problems

We present some results for positive solutions of a system of higher-order nonlinear ordinary differential equations, subject to multi-point boundary conditions.     

Behavior of asphaltene and asphaltene fractions films on a Langmuir–Blodgett trough and its relationship with proposed molecular structures

Abstract

Asphaltenes were precipitated from a Venezuelan Ayacucho crude oil and separated into two fractions (A1 and A2) by the p-nitrophenol method. The asphaltenes and the fractions A1 and A2, as well as mixtures of the two fractions were tested in a Langmuir–Bodgett trough. It was found that the asphaltenes and the fraction A2 had similar behavior and higher compressibility than the fraction A1. This is because the molecules of A2 are more flexible than the molecules of A1 as they have aliphatic chains that bond aromatic structures while the A1 has an aromatic nucleus.     

Synthesis, contact printing, and device characterization of Ni-catalyzed, crystalline InAs nanowires

InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation. The catalytic growth of nonepitaxial InAs nanowires, however, has often relied on the use of Au colloids which is non-CMOS compatible. Here, we demonstrate the successful synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on amorphous SiO2 substrates. The nanowires show superb electrical properties with field-effect electron mobility ~2700 cm2/Vs and ION/IOFF >103. The uniformity and purity of the grown InAs nanowires are further demonstrated by large-scale assembly of parallel arrays of nanowires on substrates via the contact printing process that enables high performance, “printable” transistors, capable of delivering 5 10 mA ON currents (~400 nanowires).     

Isomerization of α-Pinene Oxide Over Iron-Modified Zeolites

Fe-modified mordenite, ferrierite, Y, ZSM-5, ZSM-12 and beta zeolite catalysts were prepared by solid state ion-exchange and conventional liquid phase ion-exchange methods from aqueous solutions. Sn- modified H-beta-300 zeolite catalyst was prepared by the later method. The characterization of proton form, Fe and Sn modified zeolites was carried out using X-ray powder diffraction, scanning electron microscopy, Mössbauer spectroscopy with magnetic measurements, transmission electron microscopy, nitrogen adsorption, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma spectroscopy, thermo-gravimetric analysis and FTIR spectroscopy using pyridine as a probe molecule. Isomerization of α-pinene oxide over the Fe and Sn modified zeolite catalysts was carried out in the liquid phase using a batch-wise glass reactor. Formation of campholenic aldehyde and fencholenic aldehyde were observed to be influenced by the structure, acidity of zeolite and contents of Fe and Sn, reaction temperature and the catalysts pretreatment.     

Hydrogen adsorption and kinetics in MIL-101(Cr) and hybrid activated carbon-MIL-101(Cr) materials

Since the last 15 years, porous solids such as Metal–Organic Frameworks (MOFs) have opened new perspectives for the development of adsorbents for hydrogen storage. Among all MOF materials, the chromium (III) terephthalate-based MIL-101(Cr) is a very stable one which exhibits a good uptake capacity of hydrogen (H₂). In this study, syntheses were carried out in soft conditions without hydrofluoric acid as usually reported in literature. Moreover, activated carbon (AC) was introduced in the preparation of the MOF-based adsorbents to create hybrid materials with large specific surface areas (AC-MOF). Hydrogen storage capacities were assessed at 77 K up to 100 bar, and the measurements of adsorption isotherms were performed using both volumetric and gravimetric methods. The experimental data were shown to be in good agreement. A maximal excess hydrogen uptake of 67.4 mol kg^?1 (13.5 wt.%) has been reached by the hybrid AC-MOF adsorbent at 77 K under 100 bar. The hydrogen storage capacity was so shown to be greatly enhanced by AC addition, as a maximal value of only 41.1 mol kg^?1(8.2 wt.%) was reported for the pristine MIL-101(Cr), under the same conditions. Finally, hydrogen adsorption kinetics were examined at 77 K using experimental transient adsorption curves obtained using volumetric method, and the Linear Driving Force (LDF) model was tested for their interpretation. According to this model, diffusion coefficients could be correctly estimated only in a very low pressure range. However, for high pressures, the quasi-equilibrium assumption is not valid at the initial adsorption times, making the LDF model no more applicable for accurate determination of the average effective diffusivities. To our knowledge we present the first measurement of the adsorption kinetics of hydrogen in a hybrid carbon MOF composite material. Moreover, the adsorption performances reported in this work are the best ones achieved until now by MIL-101(Cr) doping using carbonaceous materials.