Modelling and analysis of selected dissipation processes during operation of a damper with a magnetorheological fluid

L’objectif du travail était l’analyse et la description mathématique de phénomènes de dissipation et d’absorption d’énergie produits dans les amortisseurs magnétorhéologiques dans les conditions de charges cycliques, la détermination de l’influence des paramètres de contrôle, de construction et d’exploitation et le développement des procédures permettant d’optimiser le fonctionnement du dispositif. Les essais expérimentaux réalisés ont permis d’étudier l’efficacité de l’amortisseur magnétorhéologique en fonction des paramètres fondamentaux tels que la taille de l’entrefer permettant le passage de fluide entre les chambres d’amortisseur, l’intensité du courant passant par le bobinage et la vitesse d’oscillation des sollicitations cinématiques appliquées. La simulation du fonctionnement de l’amortisseur a été réalisée à l’aide des modèles rhéologiques de Bouc-Wen et de Gamot-Filisko modifié et les résultats de deux approches ont été comparés quantitativement et qualificativement. Afin d’identifier les paramètres du modèle, la méthode d’optimisation du recuit simulé a été appliquée. La variation des paramètres identifiés du modèle rhéologique a été représentée graphiquement sous la forme des surfaces de changements. L’extrapolation des surfaces a permis d’étendre le domaine de recherche des solutions au delà de la plage des résultats disponibles expérimentalement. Les configurations caractéristiques des isolignes des paramètres ont été remarquées. Sur cette base une méthode d’analyse et de choix de paramètres du modèle a été formulée. La méthodologie proposée peut être utile à l’étape de conception, évaluation et optimisation des paramètres de fonctionnement des dispositifs à fluide magnétorhéologiqueThe purpose of this work was the analysis and the mathematical description of energy absorption and dissipation processes in magnetorheological shock absorbers submitted to cyclic loading. The influence of control, construction and exploitation parameters, and the development of procedures allowing the optimization of the device operation have been investigated. Conducted experiments allowed to determine the performance of a magnetorheological damper as a function of basic parameters such as the crevice size inside the damper’s piston head, the electric current intensity in the magnetic coil and the oscillation speed of forced kinematical input motion function. The computer simulation of the damper’s operation has been carried out with the use of two rheological models: of Bouc-Wen and a modified version of simplified Gamot-Filisko. Results of both approaches have been compared in terms of quantity and quality. In order to identify the parameters of the model, the simulated annealing optimization method has been applied. The changes of identified parameters of the rheological model have been presented graphically as surfaces of variation. The extrapolation of these surfaces allowed extending the domain of searched solutions beyond the available range of experimental results. Characteristic izolines’ configurations of model variables have been observed. Basing on this observation, a method of analysis and a way of parameters selection have been presented. The proposed methodology can be useful during design process, comparison and optimization of magnetorheological fluid device operation parameter

Modelowanie i analiza wybranych procesów dyssypacyjnych w pracy tlumika z ciecza magnetoreologiczna

L objectif du travail était l analyse et la description mathématique de phénomènes de dissipation et d absorption d énergie produits dans les amortisseurs magnétorhéologiques dans les conditions de charges cycliques, la détermination de l influence des paramètres de contrôle, de construction et d exploitation et le développement des procédures permettant d optimiser le fonctionnement du dispositif. Les essais expérimentaux réalisés ont permis d étudier l efficacité de l amortisseur magnétorhéologique en fonction des paramètres fondamentaux tels que la taille de l entrefer permettant le passage de fluide entre les chambres d amortisseur, l intensité du courant passant par le bobinage et la vitesse d oscillation des sollicitations cinématiques appliquées. La simulation du fonctionnement de l amortisseur a été réalisée à l aide des modèles rhéologiques de Bouc-Wen et de Gamot-Filisko modifié et les résultats de deux approches ont été comparés quantitativement et qualificativement. Afin d identifier les paramètres du modèle, la méthode d optimisation du recuit simulé a été appliquée. La variation des paramètres identifiés du modèle rhéologique a été représentée graphiquement sous la forme des surfaces de changements. L extrapolation des surfaces a permis d étendre le domaine de recherche des solutions au delà de la plage des résultats disponibles expérimentalement. Les configurations caractéristiques des isolignes des paramètres ont été remarquées. Sur cette base une méthode d analyse et de choix de paramètres du modèle a été formulée. La méthodologie proposée peut être utile à l étape de conception, évaluation et optimisation des paramètres de fonctionnement des dispositifs à fluide magnétorhéologiqueThe purpose of this work was the analysis and the mathematical description of energy absorption and dissipation processes in magnetorheological shock absorbers submitted to cyclic loading. The influence of control, construction and exploitation parameters, and the development of procedures allowing the optimization of the device operation have been investigated. Conducted experiments allowed to determine the performance of a magnetorheological damper as a function of basic parameters such as the crevice size inside the damper s piston head, the electric current intensity in the magnetic coil and the oscillation speed of forced kinematical input motion function. The computer simulation of the damper s operation has been carried out with the use of two rheological models: of Bouc-Wen and a modified version of simplified Gamot-Filisko. Results of both approaches have been compared in terms of quantity and quality. In order to identify the parameters of the model, the simulated annealing optimization method has been applied. The changes of identified parameters of the rheological model have been presented graphically as surfaces of variation. The extrapolation of these surfaces allowed extending the domain of searched solutions beyond the available range of experimental results. Characteristic izolines configurations of model variables have been observed. Basing on this observation, a method of analysis and a way of parameters selection have been presented. The proposed methodology can be useful during design process, comparison and optimization of magnetorheological fluid device operation parametersLILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Coinfection with Epstein–Barr Virus (EBV), Human Papilloma Virus (HPV) and Polyoma BK Virus (BKPyV) in Laryngeal, Oropharyngeal and Oral Cavity Cancer

Most research providing evidence for the role of oncogenic viruses in head and neck squamous cell carcinoma (SCC) development is focused on one type of virus without analyzing possible interactions between two or more types of viruses. The aim of this study was to analyse the prevalence of co-infection with human papillomavirus (HPV), Epstein–Barr virus (EBV) and polyoma BK virus (BKPyV) in oral, oropharyngeal and laryngeal squamous cell carcinomas in Polish patients. The correlations between viral infection, SCC, demographic parameters, evidence of metastases and grading were also investigated. Fresh-frozen tumour tissue samples were collected from 146 patients with laryngeal, oropharyngeal and oral cancer. After DNA extraction, the DNA of the studied viruses was detected using polymerase chain rection (PCR) assay. Males (87.7%) with a history of smoking (70.6%) and alcohol abuse (59.6%) prevailed in the studied group. Histological type G2 was recognized in 64.4% cases. The patients were most frequently diagnosed with T2 stage (36.3%) and with N1 stage (45.8%). Infection with at least two viruses was detected in 56.2% of patients. In this group, co-infection with HPV/EBV was identified in 34.1% of cases, EBV/BKV in 23.2%, HPV/BKV in 22.0%, and HPV/EBV/BKV in 20.7%. No difference of multiple infection in different locations of cancer was observed. The prevalence of poorly differentiated tumours (G3) was more frequent in co-infection with all three viruses than EBV or BKV alone. A significant correlation was observed between tumour dimensions (T) and lymph-node involvement (N) in co-infected patients compared to single infection. Further studies are necessary to clarify whether co-infection plays an important role in the initiation and/or progression of oncogenic transformation of oral, oropharyngeal and laryngeal epithelial cells

Serum EBV antibodies and LMP-1 in Polish patients with oropharyngeal and laryngeal cancer

Abstract Background The association between Epstein-Barr virus (EBV) and the development of head and neck cancer was reported by many researchers. The aim of the present study was to detect EBV DNA and EBV antibodies in 110 Polish patients with oropharyngeal and laryngeal cancer compared to 40 healthy individuals. Methods Frozen tumor tissue fragments were tested using nested PCR assay for EBV DNA detection. Sera from all individuals were investigated using ELISA tests to detect the presence of VCA IgM and IgG, EBNA IgG, EA IgG. Results EBV DNA was detected in 52.7% of the patients (25% in controls). EBVCA were detected in 94.5%, EBNA in 96.4% and EA in 94.5% of patients. The significantly higher level of EA in the patients suggests EBV reactivation. The majority of patients (83%) were infected with wild-type EBV. Conclusion Our study showed that this variant seems to be associated with oropharyngeal and laryngeal cancer in the Polish population

Serum and Tissue Level of TLR9 in EBV-Associated Oropharyngeal Cancer

The Epstein–Barr virus (EBV) is associated with the development of various epithelial malignancies including cancer in the head and neck region. Several studies have shown that Toll-like receptors (TLRs) are required for an innate immune response to infection with human DNA viruses, e.g., EBV. During viral infections, TLR response may influence the transformation to malignancy. The aim of the study was to assess TLR9 serum and tissue level in EBV(+) and EBV(−) oropharyngeal cancer patients. The study involved 78 patients: 42 EBV(+) and 36 EBV(−). EBV DNA was detected in fresh frozen tumor tissue. TLR9 level was measured in homogenate of tumor tissue and in serum. Moreover, in serum samples IL-10, VEGF, TGFβ, TNFα and antibodies against EBV were detected using ELISA test. TLR9 level was significantly lower in EBV(+) patients, both in tissue and serum, while EBVCA, EBNA and VEGF level was statistically higher in EBV(+) patients. An increase in EBVCA and EBNA antibodies titer was correlated with a TLR9 level decrease. TLR9 level was higher in poorly-differentiated tumors (G3), in tumor of larger dimensions (T3-T4) and with lymph nodes involvement (N3-N4) but without statistical significance. High levels of anti-EA antibodies in the majority of EBV(+) patients may point to the reactivation of EBV infection

Prevalence of Epstein-Barr virus, human papillomavirus, cytomegalovirus and herpes simplex virus type 1 in patients with diabetes mellitus type 2 in south-eastern Poland.

A microbiota is a complex ecosystem of microorganisms consisting of bacteria, viruses, protozoa, and fungi living in different niches of the human body, which plays an essential role in many metabolic functions. Modifications in the microbiota composition can lead to several diseases, including metabolic disorders. The aim of this study was to analyze the prevalence of four viruses which can cause persistent infections-Epstein-Barr virus (EBV), human papillomavirus (HPV), cytomegalovirus (CMV), and herpes simplex virus type 1 (HSV-1) in patients with diabetes mellitus type 2 (DM2). Blood, saliva and oral swabs were collected from all the study participants. The nested-PCR technique was used to detect the viral DNA. DNA of at least one virus was detected in 71.1% of diabetic patients and in 30% of individuals without diabetes. In patients with diabetes EBV DNA was detected the most frequently (25.4%), followed by HPV- 19.1%, HSV- 10.4% and CMV- 5.2%. A higher percentage of EBV+HPV co-infection was found among men (30.8%). EBV DNA was statistically more often detected in patients living in rural areas (53.7%), while HPV (91.5%) and EBV+HPV co-infection (22.2%) prevailed among patients from urban areas. In patients with a DM2 history longer than 10 years viral infection was detected more frequently. The prevalence of EBV, HPV and the EBV+HPV co-infection was significantly higher in diabetic patients than in individuals without diabetes. The frequency of these infections depended on the duration of the disease (DM2)

Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity in patients with diabetes mellitus type 2 infected with Epstein-Barr virus.

Oxidative stress is suggested to be the crucial factor in diabetes mellitus type 2 (DM2) pathogenesis and in the development of diabetic complications. Patients with DM2 may be more susceptible to infections due to hyperglycaemia-induced virulence of various microorganisms. Several studies pointed that Epstein-Barr virus (EBV) infection is associated with reactive oxygen species (ROS) production and/or activation of signalling pathways connected with ROS. The present study analyzed serum activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) in DM2 patients with and without EBV infection. Blood and saliva were collected from 120 patients with DM2. EBV DNA was detected in the saliva using nested-PCR technique. Spectrophotometric methods were implemented to determine serum GPx and SOD activity with the use of diagnostic kits produced by Randox Laboratories. GPx and SOD activity was decreased in diabetic patients, with the lowest values in DM2 EBV-positive patients. There was correlation between GPx and SOD activity-with increased value of GPx, SOD activity was also rised. In patients with DM2 history longer than 10 years as well as in DM2 patients with obesity, antioxidant enzymes activity was decreased. Determination of examined parameters may be useful in diabetic patients with EBV infection and could be important prognostic factor