A simplified formulation of wire-plate corona discharge in air: application to the ion wind simulation

The spatial distribution of charged particles (electrons, negative ions and positive ions) and electric field have been evaluated using a semi-analytical approach of the positive and negative corona discharge for a wire-to-plate electrode system. Thus, approximate formulas useful for the characterization and control of corona discharge devices are provided, which helps to significantly reduce computational costs. Based on the obtained results, the electro-hydrodynamic (EHD) force generated by the corona discharge has been determined, and it has been used in the Navier-Stokes equations to compute the spatial distribution of the gas velocity. As a result, the influence of the corona plasma region in the flow pattern, particularly in the vicinity of the corona electrode, has been brought to light, which helps to understand the different flow velocities observed in positive and negative coronas. Moreover, the influence of voltage, wire radius, and inter-electrode separation on the electric wind velocity has been investigated

The effect of the electric wind on the spatial distribution of chemical species in the positive corona discharge

The electrohydrodynamic air flow generated by a positive corona discharge, and its effect on the spatial distribution of chemical species within a wire-plate corona reactor, have been numerically simulated. The computational model is based on the solutions of the Navier- Stokes equation and the continuity equation of each chemical species generated by the electrical discharge. A simplified analytical expression of the electric force density, which only requires the current density as the input parameter, has been used in the Navier-Stokes equation to obtain the velocity field. For the solution of the continuity equations, a plasma chemistry model that includes the most important reactions between electrons, atoms and molecules in air has been used. Similar to the electric force, the electron density distribution has been approximated by using a semi-analytical expression appropriate for the electrode geometry. The results of the study show that the spatial distribution of chemical species can be very different, and depends on the interplay between the electrohydrodynamic flow, the chemical kinetics of the species and its characteristic lifetime

Parvovirus B19 infection in Tunisian patients with sickle-cell anemia and acute erythroblastopenia

<p>Abstract</p> <p>Background</p> <p>Human parvovirus B19 is the etiologic agent of erythema infectiosum in children. It is also associated with other clinical manifestations in different target groups. Patients with chronic hemolytic anemia are at high risk of developing acute erythroblastopenia following infection by the virus. They usually become highly viremic and pose an increased risk of virus transmission. Close monitoring of such high risk groups is required for epidemiologic surveillance and disease prevention activities. Here we report a molecular epidemiological study on B19 virus infection in Tunisian patients with chronic hemolytic anemia.</p> <p>Methods</p> <p>This study was conducted on 92 young chronic hemolytic anemia patients who attended the same ward at the National Bone Marrow Transplantation Center of Tunis and 46 controls from a different hospital. Screening for IgM and IgG anti-B19 antibodies was performed using commercially available enzyme immunoassays and B19 DNA was detected by nested PCR in the overlapping <it>VP1/VP2 </it>region. DNA was sequenced using dideoxy-terminator cycle sequencing technology.</p> <p>Results</p> <p>Anti-parvovirus B19 IgG antibodies were detected in 26 of 46 sickle-cell anemia patients, 18 of 46 β-thalassemia and 7 of 46 controls. Anti-parvovirus B19 IgM antibodies were detected only in 4 of the sickle-cell anemia patients: two siblings and two unrelated who presented with acute erythroblastopenia at the time of blood collection for this study and had no history of past transfusion. B19 DNA was detected only in sera of these four patients and the corresponding 288 bp nested DNA amplicons were sequenced. The sequences obtained were all identical and phylogenetic analysis showed that they belonged to a new B19 virus strain of Genotype1.</p> <p>Conclusion</p> <p>A new parvovirus B19 strain of genotype1 was detected in four Tunisian patients with sickle-cell anemia. Virus transmission appeared to be nosocomial and resulted in acute erythroblastopenia in the four patients. The possibility of independent transmission of this B19 variant to the patients is unlikely in light of the present epidemiological data. However this possibility cannot be ruled out because of the low genetic variability of the virus.</p

Cytokine and immunoglobulin production by PWM-stimulated peripheral and tumor-infiltrating lymphocytes of undifferentiated nasopharyngeal carcinoma (NPC) patients

BACKGROUND: Undifferentiated Nasopharyngeal Carcinoma (NPC) patients show a characteristic pattern of antibody responses to the Epstein-Barr virus (EBV) which is regularly associated with this tumor. However, no EBV-specific cytotoxic activity is detectable by the standard chromium-release assay at both peripheral and intratumoral levels. The mechanisms underlying this discrepancy between the humoral and cellular immune responses in NPC are still unknown, but might be related to an imbalance in immunoregulatory interleukin production. In this report, we investigated the ability of peripheral (PBL) and tumor- infiltrating (TIL) lymphocytes of undifferentiated NPC patients to produce in vitro three interleukins (IL-2, IL-6, IL-10) and three immunoglobulin isotypes (IgM, IgG, IgA). METHODS: Lymphocytes from 17 patients and 17 controls were cultured in the presence of Pokeweed mitogen (PWM) for 12 days and their culture supernatants were tested for interleukins and immunoglobulins by specific enzyme-linked immunosorbent assays (ELISA). Data were analysed using Student's t-test and probability values below 5% were considered significant. RESULTS: The data obtained indicated that TIL of NPC patients produced significantly more IL-2 (p = 0,0002), IL-10 (p = 0,020), IgM (p= 0,0003) and IgG (p < 0,0001) than their PBL. On the other hand, patients PBL produced significantly higher levels of IL-2 (p = 0,022), IL-10 (p = 0,016) and IgM (p = 0,004) than those of controls. No significant differences for IL-6 and IgA were observed. CONCLUSION: Taken together, our data reinforce the possibility of an imbalance in immunoregulatory interleukin production in NPC patients. An increased ability to produce cytokines such as IL-10 may underlie the discrepancy between humoral and cellular immune responses characteristic of NPC

Antirabies vaccination of dogs by oral way in Tunisia. Assay with baits and two attenuated virus vaccines

Quatre types d’appâts ont été testés simultanément sur 200 chiens (50 chiens/type d’appât). L’appât “tête de poulet”-TP a été significativement le meilleur appât, avec un pourcentage d’acceptation de 96% et un taux de succès vaccinal de 94 % ; l’appât industriel à base de “farine de poisson”-FP a occupé la seconde position avec un taux d’acceptation de 80% et un taux de succès vaccinal de 62%. L’essai de deux vaccins à virus atténués dérivés de la souche S AD, SAD Berne et SAG 1, a par ailleurs confirmé l’immunogénicité par la voie orale de ces souches chez le chien, et encourage donc à envisager ce mode de vaccination chez cette espèce, en complément de la vaccination par voie parentérale

A new numerical approach for efficient modeling of positive corona discharge and its associated electric wind

Research on corona wind generation has been increasing in recent years because of its potential technological applications, particularly those related to improving heat transfer in small-scale devices. Since numerical simulations play a key role in the design of these applications, computationally efficient modeling of corona discharge is imperative. This work presents a new approach that allows rapid computation of the electrohydrodynamic (EHD) force density responsible for the generation of electric wind. Arbitrary electrode configurations can easily be dealt with in the model, since only the Laplacian electric field lines have to be determined numerically. Then, using approximated analytical approximations of the electric field intensity along the field lines, the spatial distribution of the current density and the space charge density can be easily determined. The model has been satisfactorily tested against experimental measurements of the current–voltage characteristic and the current density distribution on the cathode. Furthermore, the electric wind computed from the EHD force agrees quite satisfactorily with measurements carried out in different electrode configurations. Finally, the model has been applied to a new electrode configuration that has greater potential for heat transfer applications

NF-κB-Mediated Modulation of Inducible Nitric Oxide Synthase Activity Controls Induction of the Epstein-Barr Virus Productive Cycle by Transforming Growth Factor Beta 1▿†

Transforming growth factor beta 1 (TGF-β1) signal transduction has been implicated in many second-messenger pathways, including the NF-κB pathway. We provide evidence of a novel TGF-β1-mediated pathway that leads to extracellular signal-regulated kinase (ERK) 1/2 phosphorylation, which in turn induces expression of an Epstein-Barr virus (EBV) protein, ZEBRA, that is responsible for the induction of the viral lytic cycle. This pathway includes two unexpected steps, both of which are required to control ERK 1/2 phosphorylation: first, a quick and transient activation of NF-κB, and second, downregulation of inducible nitric oxide synthase (iNOS) activity that requires the participation of NF-κB activity. Although necessary, NF-κB alone is not sufficient to produce downregulation of iNOS, suggesting that another uncharacterized event(s) is involved in this pathway. Dissection of the steps involved in the switch from the EBV latent cycle to the lytic cycle will be important to understand how virus-host relationships modulate the innate immune system