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"Comte, Pierre"
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الحياة في العراق بين أعوام 1814-1914 م
يتحدث هذا الكتاب عن الحياة في العراق إبان الحكم العثماني 1814-1914 وفيه يكتب السفير الفرنسي \"بيير دي فوصيل\" عن مجموعة وثائق هامة يرجه تاريخها على ما قبل عام 1914 وهي في مضمونها مجموعة مراسلات لكتال تلك الفترة من أولئك الذين تمرسوا وزالوا أعمالهم بين حلب وجدة وديار بكر وبغداد وهؤلاء على علم تام بأسرار الأوساط التركية والعربية التي يتكلمون بلغتها يقول فوصيل \"... أقول رغم كل هذا فإن هذه المراسلات تتضمن وصف عام انطمس اليوم كل الانطماس، لأن هذه البلاد هي عبارة عن صحارى بدون آبار نفط تخترقها القوافل البدوية فقط ومدن ذات أزقة ومنعطفات ودروب متعرجة وأسواق صاخبة تعج بالهرج والمرج والصخب والضجيج.
BOOK
Potential of PN Reduction in Passenger Cars with DPF and GPF
Particle number concentration (PN) in vehicle exhaust and ambient air describes the number of ultrafine particles (UFPs) below 500 nm, which are recognized as a toxic and carcinogenic component of pollution and are regulated in several countries. Metal nuclei, ash, and organic matter contribute significantly to the ultrafine particle size fraction and, thus, to the particle number concentration. Exhaust gas filtration is increasingly being used worldwide to significantly reduce this pollution, both on diesel particulate filter (DPF) and gasoline particulate filter (GPF) engines. In recent years, the EU has also funded research projects dealing with the possibilities of retrofitting gasoline vehicles with GPFs. This paper presents the results and compares the PN emissions of different vehicles. An original equipment manufacturer (OEM) diesel car with a DPF is considered as a benchmark. The PN emissions of this car are compared with a CNG car without filtration and with gasoline cars equipped with GPFs. It can be concluded that the currently used GPFs still have some potential to improve their filtration efficiency and that a modern CNG car would still have remarkable possibilities to reduce PN emissions with an improved quality GPF.
Journal Article
Predation and Disturbance Interact to Shape Prey Species Diversity
Though predation, productivity (nutrient richness), spatial heterogeneity, and disturbance regimes are known to influence species diversity, interactions between these factors remain largely unknown. Predation has been shown to interact with productivity and with spatial heterogeneity, but few experimental studies have focused on how predation and disturbance interact to influence prey diversity. We used theory and experiments to investigate how these factors influence diversification ofPseudomonas fluorescensby manipulating both predation (presence or absence ofBdellovibrio bacteriovorus) and disturbance (frequency and intensity of disturbance). Our results show that in a homogeneous environment, predation is essential to promote prey species diversity. However, in most but not all treatments, elevated diversity was transitory, implying that the effect of predation on diversity was strongly influenced by disturbance. Both our experimental and theoretical results suggest that disturbance interacts with predation by modifying the interplay of resource and apparent competition among prey.
Journal Article
Gas-phase composition and secondary organic aerosol formation from standard and particle filter-retrofitted gasoline direct injection vehicles investigated in a batch and flow reactor
Gasoline direct injection (GDI) vehicles have recently been identified as a
significant source of carbonaceous aerosol, of both primary and secondary
origin. Here we investigated primary emissions and secondary organic aerosol
(SOA) from four GDI vehicles, two of which were also retrofitted with a
prototype gasoline particulate filter (GPF). We studied two driving test
cycles under cold- and hot-engine conditions. Emissions were characterized by
proton transfer reaction time-of-flight mass spectrometry (gaseous
non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron
non-refractory particles) and light attenuation measurements (equivalent
black carbon (eBC) determination using Aethalometers) together with
supporting instrumentation. Atmospheric processing was simulated using the
PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow
reactor (OFR). Overall, primary and secondary particulate matter (PM) and
NMOC emissions were dominated by the engine cold start, i.e., before thermal
activation of the catalytic after-treatment system. Trends in the
SOA oxygen to carbon ratio (O : C) for OFR and SC were
related to different OH exposures, but divergences in the H : C remained
unexplained. SOA yields agreed within experimental variability between the
two systems, with a tendency for higher values in the OFR than in the SC (or,
vice versa, lower values in the SC). A few aromatic compounds dominated the
NMOC emissions, primarily benzene, toluene, xylene isomers/ethylbenzene and
C3-benzene. A significant fraction of the SOA was explained by those
compounds, based on comparison of effective SOA yield curves with those of
toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR, as well
as others from literature. Remaining discrepancies, which were smaller in the
SC and larger in the OFR, were up to a factor of 2 and may have resulted from
diverse reasons including unaccounted precursors and matrix effects. GPF
retrofitting significantly reduced primary PM through removal of refractory
eBC and partially removed the minor POA fraction. At cold-started conditions
it did not affect hydrocarbon emission factors, relative chemical composition
of NMOCs or SOA formation, and likewise SOA yields and bulk composition
remained unaffected. GPF-induced effects at hot-engine conditions
deserve attention in further studies.
Journal Article
Large-eddy simulation of a compressible flow in a three-dimensional open cavity at high Reynolds number
Large-eddy simulations of a subsonic three-dimensional cavity flow with self-sustaining oscillations are carried out for a Reynolds number based on the length of the cavity equal to $7\\,{\\times}\\,10^6$. Meticulous comparisons with available experimental data corresponding to the same configuration demonstrate a high level of accuracy. Special attention is paid to the mixing layer that develops over the cavity and two different zones are identified. The first one is dominated by Kelvin–Helmholtz instability, and the linear as well as quadratic energy transfers leading to the filling of velocity spectra are described. The Kelvin–Helmholtz instability also appears to be forced near the origin of the layer, and it is postulated that the small recirculation bubble located in this area is responsible for the forcing. Downstream of the first zone and up to the vicinity of the aft wall, the layer behaves very similarly to a free mixing layer by exhibiting a linear spreading. An influence of the recirculating flow inside the cavity upon the growth of the layer is nevertheless observed at downstream stations. Analysis of the pressure on the floor of the cavity reveals that the self-sustaining oscillation-related pressure modes (Rossiter modes) are independent of their spanwise location inside the cavity. On the contrary, Rossiter modes exhibit streamwise modulations and it is demonstrated that a very simple two-wave model is able to reproduce the spatial shape of the modes. Nonlinear interactions between Rossiter modes are encountered, as well as nonlinear interactions with low-frequency components. A joint time–frequency analysis shows a temporal modulation of the Rossiter mode levels at similar low frequencies, resulting in a special form of intermittency with competitive energy exchanges between modes.
Journal Article
Effects of an iron-based fuel-borne catalyst and a diesel particle filter on exhaust toxicity in lung cells in vitro
Metal-containing fuel additives catalyzing soot combustion in diesel particle filters are used in a widespread manner, and with the growing popularity of diesel vehicles, their application is expected to increase in the near future. Detailed investigation into how such additives affect exhaust toxicity is therefore necessary and has to be performed before epidemiological evidence points towards adverse effects of their application. The present study investigates how the addition of an iron-based fuel additive (Satacen®3, 40 ppm Fe) to low-sulfur diesel affects the in vitro cytotoxic, oxidative, (pro-)inflammatory, and mutagenic activity of the exhaust of a passenger car operated under constant, low-load conditions by exposing a three-dimensional model of the human airway epithelium to complete exhaust at the air–liquid interface. We could show that the use of the iron catalyst without and with filter technology has positive as well as negative effects on exhaust toxicity compared to exhaust with no additives: it decreases the oxidative and, compared to a non-catalyzed diesel particle filter, the mutagenic potential of diesel exhaust, but increases (pro-)inflammatory effects. The presence of a diesel particle filter also influences the impact of Satacen®3 on exhaust toxicity, and the proper choice of the filter type to be used is of importance with regards to exhaust toxicity.
Journal Article
Gasoline particle filter reduces oxidative DNA damage in bronchial epithelial cells after whole gasoline exhaust exposure in vitro
A substantial amount of traffic-related particle emissions is released by gasoline cars, since most diesel cars are now equipped with particle filters that reduce particle emissions. Little is known about adverse health effects of gasoline particles, and particularly, whether a gasoline particle filter (GPF) influences the toxicity of gasoline exhaust emissions. We drove a dynamic test cycle with a gasoline car and studied the effect of a GPF on exhaust composition and airway toxicity. We exposed human bronchial epithelial cells (ECs) for 6 hours, and compared results with and without GPF. Two hours later, primary human natural killer cells (NKs) were added to ECs to form cocultures, while some ECs were grown as monocultures. The following day, cells were analyzed for cytotoxicity, cell surface receptor expression, intracellular markers, oxidative DNA damage, gene expression, and oxidative stress. The particle amount was significantly reduced due to GPF application. While most biological endpoints did not differ, oxidative DNA damage was significantly reduced in EC monocultures exposed to GPF compared to reference exhaust. Our findings indicate that a GPF has beneficial effects on exhaust composition and airway toxicity. Further studies are needed to assess long-term effects, also in other cell types of the lung.
Journal Article
Effects of an iron-based fuel-borne catalyst and a diesel particle filter on exhaust toxicity in lung cells in vitro
Metal-containing fuel additives catalyzing soot combustion in diesel particle filters are used in a widespread manner, and with the growing popularity of diesel vehicles, their application is expected to increase in the near future. Detailed investigation into how such additives affect exhaust toxicity is therefore necessary and has to be performed before epidemiological evidence points towards adverse effects of their application. The present study investigates how the addition of an iron-based fuel additive (Satacen®3, 40 ppm Fe) to low-sulfur diesel affects the in vitro cytotoxic, oxidative, (pro-)inflammatory, and mutagenic activity of the exhaust of a passenger car operated under constant, low-load conditions by exposing a three-dimensional model of the human airway epithelium to complete exhaust at the air-liquid interface. We could show that the use of the iron catalyst without and with filter technology has positive as well as negative effects on exhaust toxicity compared to exhaust with no additives: it decreases the oxidative and, compared to a non-catalyzed diesel particle filter, the mutagenic potential of diesel exhaust, but increases (pro-)inflammatory effects. The presence of a diesel particle filter also influences the impact of Satacen®3 on exhaust toxicity, and the proper choice of the filter type to be used is of importance with regards to exhaust toxicity.
Journal Article
Large eddy simulation of compressible channel flow
Astract
The present study is a contribution to the analysis of wall-bounded compressible flows, including a special focus on wall modeling for compressible turbulent boundary layer in a plane channel. large eddy simulation (LES) of fully developed isothermal channel flows at
Re
= 3,000 and
Re
= 4,880 with a sufficient mesh refinement at the wall are carried out in the Mach number range 0.3 ≤
M
≤ 3 for two different source term formulations: first the classical extension of the incompressible configuration by Coleman et al. (J. Fluid Mech. 305:159–183, 1995), second a formulation presently derived to model both streamwise pressure drop and streamwise internal energy loss in a spatially developed compressible channel flow. It is shown that the second formulation is consistent with the spatial problem and yields a much stronger cooling effect at the wall than the classical formulation. Based on the present LES data bank, compressibility and low Reynolds number effects are analysed in terms of coherent structure and statistics. A study of the universality of the structure of the turbulence in non-hypersonic compressible boundary layers (
M
≤5) is performed in reference to Bradshaw (Annu. Rev. Fluid. Mech. 9:33–54, 1977). An improvement of the van Driest transformation is proposed; it accounts for both density and viscosity changes in the wall layer. Consistently, a new integral wall scaling (
y
c
+
) which accounts for strong temperature gradients at the wall is developed for the present non-adiabatic compressible flow. The modification of the strong Reynolds analogy proposed by Huang et al. (J. Fluid Mech. 305:185–218, 1995) to model the correlation between velocity and temperature for non-adiabatic wall layers is assessed on the basis of a Crocco–Busemann relation specific to channel flow. The key role of the mixing turbulent Prandtl number
Pr
m
is pointed out. Results show very good agreement for both source formulations although each of them involve a very different amount of energy transfer at the wall.
Journal Article
Biological Effects in Lung Cells In Vitro of Exhaust Aerosols from a Gasoline Passenger Car With and Without Particle Filter
Exhaust aerosol from gasoline passenger cars is a complex mixture of a particulate fraction as well as volatile compounds. In contrary to the observed adverse effects of diesel exhaust particles the gasoline exhaust has, however, received little attention so far. The aim of this study was to perform a comparison of exhaust composition and biological responses from freshly produced non-filtered exhaust as well as from exhaust filtered with a noncoated gasoline particle filter (GPF). A 3D model of the human epithelial airway barrier was exposed to the exhaust directly at the air-liquid interface and different effects such as cytotoxicity, antioxidative response, pro-inflammation, and activation of the aryl hydrocarbon receptor (AhR) were studied. In addition, genotoxicity was assessed using the Ames test. By an online analysis of the exhaust, it has been shown that the GPF efficiently filters the particle count in both the cold and warm phase when the new European driving cycle (NEDC) was applied. The lung cell tests revealed that the use of the GPF increased the antioxidative glutathionine (GSH) response as well as the pro-inflammatory potential, i.e.,
IL-8
, expression, indicating increased cell stimulation by the volatile compounds alone. The removal of the particulate fraction, however, decreased significantly the AhR activation in comparison to unfiltered exhaust, and the exhaust genotoxicity was reduced as tested by the Ames test. In conclusion, GPF exhaust did not completely reduce the adverse effects of gasoline exhaust in the in vitro test and further experiments with a coated GPF are needed in the future.
Journal Article