Effects of urban coarse particles inhalation on oxidative and inflammatory parameters in the mouse lung and colon

Background

Air pollution is a recognized aggravating factor for pulmonary diseases and has notably deleterious effects on asthma, bronchitis and pneumonia. Recent studies suggest that air pollution may also cause adverse effects in the gastrointestinal tract. Accumulating experimental evidence shows that immune responses in the pulmonary and intestinal mucosae are closely interrelated, and that gut-lung crosstalk controls pathophysiological processes such as responses to cigarette smoke and influenza virus infection. Our first aim was to collect urban coarse particulate matter (PM) and to characterize them for elemental content, gastric bioaccessibility, and oxidative potential; our second aim was to determine the short-term effects of urban coarse PM inhalation on pulmonary and colonic mucosae in mice, and to test the hypothesis that the well-known antioxidant N-acetyl-L-cysteine (NAC) reverses the effects of PM inhalation.

Results

The collected PM had classical features of urban particles and possessed oxidative potential partly attributable to their metal fraction. Bioaccessibility study confirmed the high solubility of some metals at the gastric level. Male mice were exposed to urban coarse PM in a ventilated inhalation chamber for 15 days at a concentration relevant to episodic elevation peak of air pollution. Coarse PM inhalation induced systemic oxidative stress, recruited immune cells to the lung, and increased cytokine levels in the lung and colon. Concomitant oral administration of NAC reversed all the observed effects relative to the inhalation of coarse PM.

Conclusions

Coarse PM-induced low-grade inflammation in the lung and colon is mediated by oxidative stress and deserves more investigation as potentiating factor for inflammatory diseases.

     

Strain-based anisotropic damage modelling and unilateral effects

A new continuum damage mechanics model is developed to describe the behaviour of quasi-brittle materials under general path loading. The induced damage is represented by a second rank symmetric tensor. The constitutive equations are based on irreversible thermodynamics theory. The strain-based model covers in an unified way the unsymmetrical behaviour in tension and in compression and the unilateral response due to crack closure effect. Uniaxial stress tests (in tension as in compression) show realistic non-linear responses in the stress–strain space. The different behaviour in both domains is covered by a single set of equations. A significant volume dilatation is noticed in compression. The model can be generalised to time-dependent phenomena.     

Investigation of the Sintering of Heterogeneous Powder Systems by Synchrotron Microtomography and Discrete Element Simulation

Collective particle behavior such as interparticle coordination and particle rearrangement plays a significant role in the sintering of heterogeneous powder systems. Those phenomena have been investigated by in situ X-ray microtomography and discrete element simulation (DEM). In situ 3D images of sintering copper-based systems have been obtained at the European Synchrotron Research Facilities. The sintered systems comprise a dense packing of atomized copper powder with a size range of 0–63 μm and the same powder including artificial pores. Quantitative analysis of these images provided valuable data on local strain, coordination number, and particle movement. The sintering of the same systems has been simulated with the discrete element code dp3D. From this set of information, the importance of collective behavior on densification and microstructural evolution is assessed and the relevance of DEM to describe it is discussed.     

Sintering of Industrial Mullites in the Presence of Magnesia as a Sintering Aid

The sinterability of two industrial mullite powders, in the presence of MgO as a sintering aid, was investigated. A glassy phase, which was generated during preparation, was present in both powders; this glassy phase had a strong influence on sintering, depending on its content, composition, and spatial distribution. MgO promoted sintering in the presence of a liquid phase, both in the as-received materials and in samples washed with HF, in which most of the pre-existing glassy phase was eliminated. Investigations using transmission electron microscopy, coupled with energy-dispersive spectroscopy, as well as dilatometric measurements and X-ray diffraction data, on washed and unwashed materials and on quenched and slow-cooled samples allowed a better understanding of the influence of MgO and the glassy phase on the sintering behavior and the formation of new phases. Most of the phases, in fact, can be explained by using the MgO–Al₂O₃–SiO₂ phase diagram, even in such complex systems.     

Comparison of Urinary Scents of Two Related Mouse Species, <Emphasis Type="Italic">Mus spicilegus</Emphasis> and <Emphasis Type="Italic">Mus domesticus</Emphasis>

Whereas the house mouse (Mus domesticus) has been studied extensively in terms of physiology/behavior and pheromonal attributes, the evolutionarily related mound-building mouse (Mus spicilegus) has received attention only recently due to its divergent behavioral traits related to olfaction. To date, no chemical studies on urinary volatile compounds have been performed on M. spicilegus. The rationale for our investigations was to determine if there are differences in urinary volatiles of intact and castrated M. spicilegus males and to explore further whether this species could utilize the same or structurally similar pheromones as the male house mouse, M. domesticus. The use of capillary gas chromatography/mass spectrometry (GC-MS) together with sorptive stir bar extraction sampling enabled quantitative comparisons between the intact and castrated M. spicilegus urinary profiles. Additionally, through GC-MS and atomic emission (sulfur-selective) detection, we identified qualitative molecular differences between intact M. spicilegus and M. domesticus. A series of volatile and odoriferous lactones and the presence of coumarin were the unique features of M. spicilegus, as was the notable absence of 2-sec-butyl-4,5-dihydrothiazole (a prominent M. domesticus male pheromone) and other sulfur-containing compounds. Castration of M. spicilegus males eliminated several substances, including δ-hexalactone and γ-octalactone, and substantially decreased additional compounds, suggesting their possible role in chemical communication. Some other M. domesticus pheromone components were also found in M. spicilegus urine. These comparative chemical analyses support the notion of metabolic similarities as well as the uniqueness of some volatiles for M. spicilegus, which may have a distinct physiological function in reproduction and behavior.     

Modeling of a continuous rotary reactor for carbon nanotube synthesis by catalytic chemical vapor deposition

The modeling of carbon nanotube production by the CCVD process in a continuous rotary reactor with mobile bed was performed according to a rigorous chemical reaction engineering approach. The geometric, hydrodynamic, physical and physicochemical factors governing the process were analyzed in order to establish the reactor equations. While the study of the hydrodynamic factor suggests a co‐current plug‐flow approximation, the physical factor mainly deals with the phenomena of transport and the transfer of mass, which can be neglected. Concerning the physicochemical factor, the modeling is based on knowledge of the expression of the initial reaction rate, and takes into account catalytic deactivation as a function of time, according to a sigmoid decreasing law. The reactor modeling allows obtaining the evolution of partial pressure, carbon nanotube production and catalytic deactivation along the reactor for given initial operating conditions. The comparison between experimental and calculated production highlights a very good fit of data. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Structural Modifications of DAPY Analogues with Potent Anti‐HIV‐1 Activity

A novel series of diarylpyrimidine analogues (DAPYs) featuring a naphthyl moiety at the C4 position were designed, with all compounds exhibiting strong activity against wild‐type HIV‐1.

     

Thermal Ageing Induced Effects on Pd/LaFeO3 for NOx Reduction by Hydrocarbons: Influence of the Preparation Method

The influence of the support synthesis for the preparation of supported Pd/LaFeO₃ perovskite based catalysts and the nature of the palladium precursor on the catalytic performances in the selective reduction of NO to N₂ by hydrocarbons have been investigated. According to the preparation method, subsequent surface and bulk characterisation revealed significant changes in the degree of dispersion and the chemical environment of oxidic palladium species depending on the extent of interaction with the support. Pd nitrate precursor leads to the stabilisation of the Pd surface concentration. The metal support interactions thus obtained strongly enhance the catalytic performances, particularly the resistance to thermal ageing whereas sol–gel synthesis produces the higher support activity.     

Mechanical Property of HVOF Inconel 718 Coating for Aeronautic Repair

The module of elasticity is one of the most important mechanical properties defining the strength of a material which is a prerequisite to design a component from its early stage of conception to its field of application. When a material is to be thermally sprayed, mechanical properties of the deposited layers differ from the bulk material, mainly due to the anisotropy of the highly textured coating microstructure. The mechanical response of the deposited layers significantly influences the overall performance of the coated component. It is, therefore, of importance to evaluate the effective module of elasticity of the coating. Conventional experimental methods such as microindentation, nanoindentation and four-point bending tests have been investigated and their results vary significantly, mainly due to inhomogeneous characteristics of the coating microstructure. Synchrotron radiation coupled with a tensile test rig has been proposed as an alternative method to determine the coating anisotropic elastic behavior dependence on crystallographic orientations. The investigation was performed on Inconel 718 (IN718) HVOF coatings sprayed on IN718 substrates. Combining these experimental techniques yield a deeper understanding of the nature of the HVOF coating Young’s modulus and thus a tool for Design Practice for repair applications.