ABSTRACT
Considering that modern wastewater and solid waste processing facilities seek efficient energy recovery methods, this study investigates anaerobic-aerobic sequential systems for combined treatment of raw wastewater with food waste. The optimum loading rate was found to be 1.6mgVSL-1d-1 resulting in a stable operation of the anaerobic compartment. Yet, the increase in ammonia concentration resulted in gradual accumulation of VFA, until reaching a tipping point of 3000mgL-1 beyond which an abrupt increase in VFA to above 6000mgL-1 was observed, with acute stability loss and performance deterioration. The aerobic system was modeled using computational fluid dynamics methods. Optimum performance was achieved at an average strain rate magnitude of 12.7s-1 yielding a DO concentration of 4mgL-1 which have resulted in 74% conversion of ammonia nitrogen. Under optimum conditions, the studied AASS yielded high total removal rates of 93% VS and 94% COD, with a high specific methane yield of 845LkgVS-1 and a CO2-to-CH4 ratio of 0.63.
Subject(s)
Food , Waste Disposal, Fluid , Wastewater , Ammonia , Anaerobiosis , Bioreactors , Methane , Solid WasteABSTRACT
Microbeam facilities provide a unique opportunity to investigate the effects of ionising radiation on living biological cells with a precise control of the delivered dose. This paper describes dosimetry calculations performed at the single-cell level in the microbeam irradiation facility available at the Centre d'Etudes Nucléaires de Bordeaux-Gradignan in France, using the object-oriented Geant4 Monte Carlo simulation toolkit. The cell geometry model is based on high-resolution three-dimensional voxelised phantoms of a human keratinocyte (HaCaT) cell line. Such phantoms are built from confocal microscopy imaging and from ion beam chemical elemental analysis. Results are presented for single-cell irradiation with 3 MeV incident alpha particles.
Subject(s)
Algorithms , Cell Physiological Phenomena/radiation effects , Models, Biological , Radiometry/methods , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Conformal/methods , Computer Simulation , Humans , Models, Statistical , Monte Carlo Method , Radiotherapy DosageABSTRACT
A comparison of three cellular irradiation techniques using the Monte Carlo simulation toolkit Geant4 is presented in this paper. They involve electrodeposited source of alpha particle-emitting radionuclides, random classical alpha beam irradiation and single cell targeted irradiation using a focused alpha microbeam line. The simulation allows the calculation of hit distributions among the cellular population as well as the absorbed dose for two typical cellular geometries.
Subject(s)
Cell Culture Techniques/methods , Cell Physiological Phenomena/radiation effects , Models, Biological , Monte Carlo Method , Particle Accelerators , Radiometry/methods , Software , Alpha Particles , Computer Simulation , Dose-Response Relationship, Radiation , Models, Statistical , Radiation Dosage , Reproducibility of Results , Scattering, Radiation , Sensitivity and SpecificityABSTRACT
The ionic channels (particularly, K+ and Ca2+ channels) regulate, via the membrane potential, the ionic distribution into the vascular cells. Micro-particule induced X-ray emission (PIXE) analysis was applied to determine the ionic composition of vascular smooth muscle cells (VSMCs) and of vascular endothelial cells (VECs) in the placental human allantochorial vessels in a physiological medium (Hanks' solution) modified by the addition of a NO donor (sodium nitroprusside, SNP) and of a beta-adrenergic stimulator (isoproterenol, ISO). The addition of SNP or ISO induced no modification of the Na, K, Cl, P, S, Mg and Ca concentrations in VSMCs. In VECs, a same effect was observed except an increase of the Mg concentration with ISO. Theses results indicated a retroactive control (active feedback) of the internal ionic distribution by endothelial factors, ionic channels and exchangers.
Subject(s)
Chorioallantoic Membrane/chemistry , Endothelium, Vascular/chemistry , Ions/analysis , Isoproterenol/pharmacology , Muscle, Smooth, Vascular/chemistry , Nitroprusside/pharmacology , Placenta/blood supply , Adrenergic beta-Agonists/pharmacology , Electron Probe Microanalysis , Endothelium, Vascular/drug effects , Endothelium, Vascular/metabolism , Female , Humans , Ion Channels/drug effects , Ion Channels/physiology , Ions/metabolism , Muscle, Smooth, Vascular/drug effects , Muscle, Smooth, Vascular/metabolism , Nitric Oxide Donors/pharmacology , Placenta/drug effects , PregnancyABSTRACT
The membrane potential, a regulator of vascular tone, is a function of the physiological activities of ionic channels (particularly, K+ and Ca2+ channels in these cells). These channels regulate the ionic distribution into these cells. Micro-particule induced X-ray emission (PIXE) analysis was applied to determine the ionic composition of vascular smooth muscle cells (VSMCs) and of vascular endothelial cells (VECs) in the placental human allantochorial vessels in a physiological medium (Hanks'solution) modified by the addition of a chemical stimulus: 5-hydroxytryptamine (5-HT), an activator of the voltage-sensitive Ca2+ channels. In VSMCs (media layer), the addition of 5-HT induced no modification of the Na, K, Cl, P, S and Ca concentrations but increased Mg concentration. In endothelium (VECs) 5-HT addition implicated an increase of the K, S, Ca concentrations, the concentration of the other ions remained constant. In VECs, Ca and K increase is due to open of L-type voltage-dependent Ca2+ channels and of K(Ca) channels. 5-HT induces also a secretion of endothelium hyperpolarizing factors which implicate decrease of [Ca2+]i in VSMCs opposite to a direct increase by 5-HT. Increase in [Mg2+]i may be due to activation of the Ca/Mg exchanger.
