Filtration of nanoparticles: Evolution of cake structure and pressure-drop

The detailed three-dimensional accumulation of deposits and the build-up of pressure-drop during filtration of compressible gases laden with nanoparticles (diameter d_p=50 nm) through capillaries (1–4 μm radius) was investigated by Langevin dynamics (LD) at Peclet number, Pe, 0.01–10. At low Pe, highly porous (98%) deposits were formed while at higher Pe the porosity was slightly reduced including a void cone upstream of the capillary inlet. Three distinct deposition regimes were identified: capillary deposition, clogging and cake growth. At the time of clogging (t_cl), a filter cake with constant solid volume fraction began to form, accompanied with build-up of pressure-drop which was in excellent agreement with classic cake filtration theory. An expression for the solid volume fraction of the cake (φ_sd,c) was obtained as a sole function of Pe. In addition, the filtration efficiency became 1 after clogging, since the cake acts as a perfectly efficient filter. Penetration of nanoparticles takes place until the onset of cake filtration at high Pe (1–10) while for smaller ones (0.01–0.1) it is negligible at the employed capillary radii and length (10 μm). Analytical expressions for the time of capillary clogging and height of the void cone were derived and were in agreement to LD simulations. The height of the void cone is in the order of one capillary diameter at high Pe.     

Disease Outcome and Brain Metabolomics of Cyclophilin-D Knockout Mice in Sepsis

Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction resulting from a systemic inflammatory response to infection, but the mechanism remains unclear. The mitochondrial permeability transition pore (MPTP) could play a central role in the neuronal dysfunction, induction of apoptosis, and cell death in SAE. The mitochondrial isomerase cyclophilin D (CypD) is known to control the sensitivity of MPTP induction. We, therefore, established a cecal ligation and puncture (CLP) model, which is the gold standard in sepsis research, using CypD knockout (CypD KO) mice, and analyzed the disease phenotype and the possible molecular mechanism of SAE through metabolomic analyses of brain tissue. A comparison of adult, male wild-type, and CypD KO mice demonstrated statistically significant differences in body temperature, mortality, and histological changes. In the metabolomic analysis, the main finding was the maintenance of reduced glutathione (GSH) levels and the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio in the KO animals following CLP. In conclusion, we demonstrate that CypD is implicated in the pathogenesis of SAE, possibly related to the inhibition of MPTP induction and, as a consequence, the decreased production of ROS and other free radicals, thereby protecting mitochondrial and cellular function.     

Flame spray pyrolysis synthesis and aerosol deposition of nanoparticle films

The assembly of nanoparticle films by flame spray pyrolysis (FSP) synthesis and deposition on temperature‐controlled substrates (323–723 K) was investigated for several application‐relevant conditions. An exemplary SnO₂ nanoparticle aerosol was generated by FSP and its properties (e.g., particle size distribution), and deposition dynamics were studied in details aiming to a simple correlation between process settings and film growth rate. At high precursor concentrations (0.05–0.5·mol/L), typically used for FSP synthesis, the nanoparticles agglomerated rapidly in the aerosol leading to large (>100 nm) fractal‐like structures with low diffusivity. As a result, thermophoresis was confirmed as the dominant nanoparticle deposition mechanism down to small (≈40 K) temperature differences (ΔT) between the aerosol and the substrate surface. For moderate‐high ΔT (>120 K), thermal equilibrium was rapidly obtained yielding a constant thermophoretic flux and film growth rate. A model was developed to predict the nanoparticle deposition rates by FSP synthesis at moderate‐high ΔT that does not require detailed analysis of the aerosol composition. Comparison with previous studies having similar nozzle geometries showed that the deposition rates of FSP‐made aerosols can be reasonably well predicted for various materials and flame conditions. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Hepatic hyperplasia and cancer in rats: metabolic alterations associated with cell growth

BACKGROUND & AIMS: We showed previously that the peroxisome proliferators di(2-ethylhexyl)phthalate (DEHP), clofibrate, and 4-chloro-6-(2,3 xylidino)-2-pyrimidinylthio (N-beta-hydroxyl)acetamide (BR931) alter hepatic sex steroid metabolism and receptor expression during induction of hepatic hyperplasia and hepatocellular carcinoma (HCC) in rats. The aim of this study was to identify metabolic changes associated with cell growth during hyperplasia and HCC. METHODS: Hepatic hyperplasia was induced in male rats by a diet containing DEHP and clofibrate for 3-60 days. HCC was induced by feeding a diet containing BR931, a more potent hepatocarcinogen, for 10 months. RESULTS: Cholesterol biosynthesis was depressed in hyperplastic livers but increased in HCC. Glucose-6-phosphate dehydrogenase (G6PD) activity was inhibited in hyperplastic liver as well as in HCC, whereas malic enzyme activity increased severalfold. Protein and messenger RNA (mRNA) levels for both G6PD and malic enzyme increased in hyperplastic livers and HCC. mRNA levels for 3-hydroxy-3-methylglutaryl-coenzyme A reductase decreased in hyperplasia and increased in HCC, whereas low-density lipoprotein receptor mRNA increased in hyperplasia and decreased in HCC. CONCLUSIONS: Neoplastic cells acquire a growth advantage by their capacity to synthesize cholesterol and obtain reduced nicotinamide adenine dinucleotide phosphate by the malic enzyme pathway when G6PD activity is inhibited by peroxisome proliferators.     

TENET: a new hybrid network architecture for adversarial defense

International Journal of Information Security - Deep neural network (DNN) models are widely renowned for their resistance to random perturbations. However, researchers have found out that these...