ARP-P4: deep analysis of a hybrid SDN ARP-Path/P4Runtime switch

Telecommunication Systems - The Software-Defined Networking (SDN) architecture decouples the control plane from the data plane, but it does not explicitly state where the control should be located....     

Effect of iron salt on the color removal of water containing the azo-dye reactive blue 69 using photo-assisted Fe(II)/H2O2 and Fe(III)/H2O2 systems

The effect of chloride, sulfate and nitrate anions on the color removal of water containing the azo-dye reactive blue 69 (RB69) in acidic solution, by using photo-assisted Fenton process with Fe(II)/H₂O₂ and Fe(III)/H₂O₂ systems was investigated. Experiments were conducted in a batch reactor irradiated during 5 h with a domestic 15 W lamp with emission in the visible spectra. Experimental results showed color disappearance in the first 5 min of reaction in the photo-assisted process for all of the different salts, greatly enhancing the reaction rate with respect to the corresponding systems under dark conditions. The exception of the general trend was the Fe₂(SO₄)₃/H₂O₂/UV system, where the decolorization process is slower probably because the oxidative species generated by rupture of Fe(III)–peroxo complexes are less reactive. Total organic matter depletion and mineralization of the effluent were also tested during the experimental runs by means of total organic carbon (TOC) showing that, for most of the photo-assisted experiments high mineralization was reached after 3 h of reaction.     

Characterization of polysaccharide production of Haemophilus influenzae type b and its relationship to bacterial cell growth

Haemophilus influenzae type b (Hib) causes invasive infections in infants and young children. Vaccines consisting of Hib capsular polysaccharide (polymer of ribosylribitol phosphate [PRP]) conjugated to a protein are effective in the prevention of such infections. The production of capsular polysaccharide type b was studied in three cultivation conditions: single, glucose pulse, and repeated batch. Specific polysaccharide production (Y _p/x ) was calculated for all experiments, showing the following values: 67 (single-batch cultivation), 71 (glucose pulse), 75 (repeated-batch cultivation, first batch), and 87 mg of PRP/g of dry cell weight (DCW) (repeated-batch cultivation, second batch). Biomass concentration reached ∼1.8 g of DCW/L, while polysaccharide concentration was about ∼132 mg/L in the three fermentation runs. Polysaccharide synthesis is associated with cell growth in all studied conditions as established by Kono's analysis and Luedeking-Piret's model.     

Evaluation of on-line high-performance size-exclusion chromatography, differential refractometry, and multi-angle laser light scattering analysis for the monitoring of the oligomeric state of human immunodeficiency virus vaccine protein antigen

Chiron has developed a novel mutant form of the human immunodeficiency virus (HIV) envelop protein, o-gp140, that is currently entering Human Phase 1 clinical trials for testing as a prophylactic HIV vaccine. The o-gp140 protein is oligomeric and the quaternary structure is thought to play an important role in its activity as an antigen. As o-gpl40 proceeds through the clinical trial process and prior to marketing approval, analytical methods that are able to demonstrate manufacturing consistency with respect to degree of oligomerization will need to be developed and validated. On-line high-performance size-exclusion chromatography, differential refractometry, and multi-angle laser light scattering analysis (HPSEC-RI-MALLS), a method commonly used to obtain the molar mass of macromolecules based on the Rayleigh-Gans-Debye approximation, was evaluated for this purpose. The results obtained demonstrated intra- and inter-day precisions to be 0.9 and 3.6% R.S.D., respectively. Accuracy was found to be equal to, or better than, 11% when comparing the known molar masses of test proteins to that of the molar masses determined by the method. Additionally, the method compared favorably to orthogonal native polyacrylamide gel electrophoresis and ultracentrifugation analyses. R-factor analysis was used to demonstrate that HPSEC-RI-MALLS is capable of discriminating compositional differences between o-gpl40 test lots. Based on the data presented, HPSEC-RI-MALLS may be a suitable manufacturing control method.     

Bifurcation Analysis of the Bulk Propylene Polymerization in the LIPP Process

Summary: A dynamic model is built to describe the bulk propylene polymerization in stirred tank reactors (LIPP process), assuming that catalyst deactivation takes place and that the reactor temperature must be controlled with the help of reflux condensers and external heat exchangers. Simulation results show that the dynamic behavior of the LIPP process can be much more complex than described previously, when catalyst deactivation and the performance of the real temperature controller are taken into consideration. Particularly, it is shown that chaotic behavior can be observed in very wide ranges of operation conditions when the more realistic operation conditions are considered.     

Brazilian bioethanol program

Brazil is the largest producer of bioethanol, and sugarcane is the main raw material. Bioethanol, is produced by both batch and continuous processes, and in some cases, flocculating yeast is use. This article analyzes the Bracilian Ethanol Program. for the 1996–1997 havest, Brazil produced 14.16 billion L of ethanol and 13.8 million metrict of sugar, from 286 million metrict of sugarcane. These products were produced by 328 industries inactivity, with 101 autonomousethanol plants producing only ethanol, and 227 sugar mills producing sugar and ethanol. The sugar-ethanol market reaches about 7.5 billion US$/yr, accounting for direct and indirect revenues.     

Viscoelastic flow simulation of polytetrafluoroethylene (PTFE) paste extrusion

Polytetrafluoroethylene (PTFE) is known to be a polymer that shows inherent microstructure formation during cold processing such as paste extrusion. To model such a complex flow, a viscoelastic constitutive equation is proposed that takes into account the continuous change of the paste microstructure during flow, through fibril formation. The mechanism of fibrillation is captured through a microscopic model for a structural parameter ξ that represents the percentage of fibrillated domains of the paste. The proposed viscoelastic constitutive equation consists of a viscous shear-thinning term (Carreau model) and an elastic term (modified Mooney–Rivlin model), the relative contribution of the two depending on ξ. The viscous and elastic parameters of the model are determined by using shear and extensional rheometry on the paste. Finite element simulations based on the proposed constitutive relation with the measured model parameters predict reasonably well the variations of the extrusion pressure with the apparent shear rate and the die geometrical characteristics.