Priority pollutants in urban stormwater: Part 1 – Case of separate storm sewers

Organic and mineral pollutants have become part of today's urban environment. During a rain event, stormwater quality as well as the corresponding contaminant loads is affected by both atmospheric deposition and the various types of impervious surfaces (roads, rooftops, parking lots etc.) on which runoff occurs. This study provides results on stormwater pollution in Paris and its suburbs from three separate storm sewers (n = 20 samples). These results show that the stormwater had been contaminated by 55 chemical substances out of the 88 investigated. A particular attention was given to stormwater particle contamination. Concentrations are provided for: metals, PAHs, PCBs, organotins, alkylphenols, phthalates, pesticides, and VOCs. Our findings are among the first available in the literature since the relevant analyses were all conducted on both the particulate (P) and dissolved (D) phases. For most substances, particles from the three storm sewers were more heavily contaminated than dredged sediments and settleable particles from the Seine River. As a consequence of this finding, the release of untreated stormwater discharges may impact the receiving waters and contribute to sediment contamination.     

Polymeric dual-slab waveguide interferometer for biochemical sensing applications

A polymer based dual-slab waveguide Young's interferometer was demonstrated for biochemical sensing. Evanescent field is utilized for probing the binding events of biomolecules on the waveguide surface. Refractive index sensing in analyte and protein adsorption on the sensing surface were investigated with glucose de-ionized water solution and bovine serum albumin, immunoglobulin G solutions in phosphate buffered saline buffer. A detection limit of 10(-5) RIU and 4 pg/mm(2) was achieved for homogeneous and surface sensing, respectively. Also, the influence of water absorption inside the polymeric device on the measurement stability was evaluated. The results indicate that the waveguide polymer sensor fabricated with the spin coating technique can achieve a satisfactory sensitivity for homogeneous refractive index sensing and, as well, for monitoring molecular binding events on the surface.     

Deposition of nanocrystalline translucent h-BN films by chemical vapor deposition at high temperature

h-BN layers were deposited on α-SiC and sapphire substrates by chemical vapor deposition at high temperature (1500-1900 °C) using B₂H₆ and NH₃ diluted in Ar. Growth rates were in the 6-10 μm/h range. In all the conditions studied, the as deposited BN layers were found to be translucent to light, some having a light whitish aspect and other a more yellowish one. It was also observed that the deposit was not always adhesive. Characterizations showed that the layers were nano-crystalline with crystallite size < 10 nm. The growth rate was found to be temperature and N/B ratio dependent due to an N limited growth regime which is more pronounced above 1700 °C.     

Biomechanics of the cardiovascular system: the aorta as an illustratory example.

Biomechanics relates the function of a physiological system to its structure. The objective of biomechanics is to deduce the function of a system from its geometry, material properties and boundary conditions based on the balance laws of mechanics (e.g. conservation of mass, momentum and energy). In the present review, we shall outline the general approach of biomechanics. As this is an enormously broad field, we shall consider a detailed biomechanical analysis of the aorta as an illustration. Specifically, we will consider the geometry and material properties of the aorta in conjunction with appropriate boundary conditions to formulate and solve several well-posed boundary value problems. Among other issues, we shall consider the effect of longitudinal pre-stretch and surrounding tissue on the mechanical status of the vessel wall. The solutions of the boundary value problems predict the presence of mechanical homeostasis in the vessel wall. The implications of mechanical homeostasis on growth, remodelling and postnatal development of the aorta are considered.     

A High Performance 700?GHz Feed Horn

We present a design of a high performance horn operating at 700 GHz. The feed, which comprises three smooth-walled conical sections, is easy to machine and yet has comparable performance to a corrugated horn. The measured radiation patterns show high main beam circularity, low sidelobe level and good agreement with theoretical predictions. The cross-polar level is below −20 dB across a frequency bandwidth of 140 GHz. The new design allows the fabrication of high performance, large format feed arrays cheaply and rapidly.     

Circadian rhythm of heart rate variability is reversibly abolished in ischemic stroke

BACKGROUND AND PURPOSE: Acute brain infarction significantly decreases heart rate variability as a result of cardiovascular autonomic dysregulation. However, information regarding circadian rhythms of heart rate and heart rate variability is limited. METHODS: In this prospective study, we analyzed 24-hour circadian rhythm of heart rate and the time and frequency domain measures of heart rate variability in 24 patients with hemispheric brain infarction, 8 patients with medullary brainstem infarction, and 32 age- and sex-matched healthy control subjects. ECG data were obtained from the patients in the acute phase and at 6 months after the infarction. RESULTS: In the acute phase of stroke, all the components of heart rate variability, ie, standard deviation of RR intervals, total power, high-frequency power, low-frequency power, and very-low-frequency power, were similar at night (from midnight to 6 AM) and during the day (from 9 AM to 9 PM), indicating that the circadian oscillation of heart rate variability had been abolished. At 6 months after brain infarction, the circadian rhythm had returned and, as in the control subjects, the values at night were significantly higher than those in the daytime. The values in hemispheric and in brainstem infarction did not differ significantly from each other. CONCLUSIONS: These results suggest that circadian fluctuation of heart rate variability is reversibly abolished in the acute phase of ischemic stroke and that it returns during the subsequent 6 months. The loss of the relative vagal nocturnal dominance may contribute to the incidence of cardiac arrhythmias and other cardiovascular complications after acute stroke.     

Ethoxylated polyethylenimine as an efficient electron injection layer for conventional and inverted polymer light emitting diodes

We report inverted light emitting devices using ethoxylated polyethylenimine (PEIE) as a single electron injection layer for indium tin oxide cathode, which possess comparable efficiency to those using ZnO/PEIE double electron injection layers. Implementation of a PEIE layer between light emitting polymer layer and aluminum has been shown to significantly enhance device efficiency as well. Improvement of device efficiency can be attributed to increased electron injection due to the reduced work function of PEIE modified cathode as well as the hole blocking effect of PEIE layer. Furthermore, PEIE serves as an efficient electron injector for a range of light emitting polymers with wide distribution of energy levels.