A Thermomechanical Modeling and Experimental Validation of the Gear Finish Hobbing Process

Naoual Sabkhi,Abdelhadi Moufki,Mohammed Nouari,Armansyah Ginting 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.3

The current research work aims at developing an analytical modelling of the gear finish hobbing process when the uncut chip thickness may be very small. Numerical models and particularly finite element simulations of this complex material removal process are often limited to one tooth because of the high required computational time. To analyze the performance characteristics of this process, a predictive approach for finish gear hobbing based on an analytical model of orthogonal cutting operation is proposed. To reduce the computational time, a new calculation strategy has been developed. This allows to examine the local parameters which change significantly for each tooth. During the finishing hobbing process of large gears (6 m < diameter < 16 m), the industrial conditions require low cutting speeds (less than 1 m/s) with lubrication. Therefore, in order to consider the effect of lubrication, cutting speed and uncut thickness on the friction coefficient, an appropriate friction law was identified from orthogonal cutting tests. The cutting model has been experimentally validated for different cutting conditions. Finally, the effects of hobbing process on the cutting forces and the tool-chip contact parameters (contact length, pressure, frictional stress and temperature) have been investigated and deeply analyzed using the developed model. The distributions of these local parameters, at each tooth rake face, may be used as a process signature for the resulting condition of the machined surface and subsurface layers.

In Vitro and In Vivo Studies Demonstrate Anticancer Property of Root Extract of Polygala senega

Saili Paul,Naoual Boujedaini,Soumya Sundar Bhattacharyya,Sushil Kumar Mandal,Anisur Rahman Khuda-Bukhsh 사단법인약침학회 2010 Journal of Acupuncture & Meridian Studies Vol.3 No.3

Polygala senega is extensively used in traditional systems of medicine against various lung diseases including cancer. In the present study we tested the anticancer potentials of ethanolic extract of roots of P. senega (generally used as a homeopathic drug)in a mammalian model, where mice, in vivo, were treated chronically with benzo[a]pyrene and in vitro where lung adenocarcinoma cell line (A549) were used. We deployed various parameters like cell viability assay, chromatin condensation studies with Hoechst 333258 staining, and maintained suitable controls. To understand the possible signal transduction pathways, expression of various signal proteins such as Aryl Hydrocarbon receptor (AhR), cytochrome P450 (CYP1A1), Bcl-2, proliferating cell nuclear antigen (PCNA), Bax and Caspase-3 was studied. Additionally,reverse transcriptase polymerase chain reaction analysis of AhR, p53, PCNA and β-actin (housekeeping) genes was made. Immunohistochemical localization of PCNA proteins was also conducted in vivo. Feeding of root extract of P. senega to mice (at the rate of 50 mg/kg and 100 mg/kg bw) chronically treated with the carcinogen (50 mg/kg bw dissolved in olive oil) showed positive modulation in expression of signal proteins. Upregulation of apoptotic signals such as p53, Caspase-3 and Bax,and downregulation of AhR, cytochrome P450 (CYP1A1), Bcl-2 and PCNA were observed. Addition of root extract of Polygala Senega (at doses of 50 μg and 100 μg)into culture medium containing A549 cells induced recovery of decreased cell viability and increased chromatin fragmentation (apoptosis).Therefore, results of both in vivo and in vitro studies scientifically validate its potential use as an anticancer agent, particularly against lung cancer, and provide important information potentially helpful in drug designing.

Study of the performance of a thermoelectric generator transformation of the thermal energy conveyed by a heat transfer fluid into electrical energy

Jennah Sara,Belouaggadia Naoual,Ezzine Mohammed,Lbibb Rachid 한국물리학회 2022 Current Applied Physics Vol.43 No.-

A mathematical model to predict the maximum energy conversion efficiency of the thermoelectric generator is developed to improve the performance and maximize the energy conversion efficiency of the thermoelectric power generator. The studied device corresponds to an original configuration of thermoelectric modules mounted on the peripheral surfaces of two channels, one of the channels is crossed by hot fluid and the other by a cold fluid. First, the effect of the flow rate was studied to choose the flow rate adapted to our study for three different configurations of the thermopile, the co-current configuration, the counter-current configuration, and the sandwich configuration. Then a comparison was made to choose the best configuration between these three studied configurations by addressing their thermoelectric performances. The results revealed that the sandwich configuration is much better than the co-current and counter-current configurations and reduces the surface area occupied by the TEG by half while generating more power than a solar panel.

Ethanolic extract of Condurango (Marsdenia condurango) used in traditional systems of medicine including homeopathy against cancer can induce DNA damage and apoptosis in non small lung cancer cells, A549 and H522, in vitro

Sourav Sikdar,Avinaba Mukherjee,Naoual Boujedaini,Anisur Rahman Khuda-Bukhsh 셀메드 세포교정의약학회 2013 셀메드 (CellMed) Vol.3 No.1

In traditional systems of medicine including homeopathy, the Condurango extract (Con) is often used to cure stomach cancer mainly, without having any scientific validation of its anti-cancer ability. Con has therefore been tested against non-small-cell lung cancer cells (NSCLC) A549 and NCI-H522 (H522) known to contain the KRAS mutation, making them resistant to most chemotherapeutic agents. As cancer cells generally defy cytotoxicity developed by chemopreventive agents and escape cell death, any drug showing the capability of preferentially killing cancer cells through apoptosis is worth consideration for judicious application. A549 and H522 cells were exposed to 0.35 µg/µl and 0.25 µg/µl of Con, respectively, for 48 h and analysed based on various protocols associated with apoptosis and DNA damage, such as MTT assay to determine cell viability, LDH assay, DNA fragmentation assay, comet assay, and microscopical examinations of DNA binding fluorescence stains like DAPI, Hoechst 33258 and acridine orange/ethidium bromide to determine the extent of DNA damage made in drug-treated and untreated cells and the results compared. Changes in mitochondrial membrane potential and the generation of reactive oxygen species were also documented through standard techniques. Con killed almost 50% of the cancer cells but spared normal cells significantly. Fluorescence studies revealed increased DNA nick formation and depolarized membrane potentials after drug treatment in both cell types. Caspase-3 expression levels confirmed the apoptosis-inducing potential of Con in both the NSCLC lines. Thus, overall results suggest considerable anticancer potential of Con against NSCLC in vitro, validating its use against lung cancer by practitioners of traditional medicine including homeopathy.

The Potentized Homeopathic Drug, Lycopodium clavatum (5C and 15C) Has Anti-cancer Effect on HeLa Cells In Vitro.

Asmita Samadder,Anisur Rahman Khuda-Bukhsh,Sreemanti Das,Jayeeta Das,Avijit Paul,Naoual Boujedaini 사단법인약침학회 2013 Journal of Acupuncture & Meridian Studies Vol.6 No.4

Cancer is a disease that needs a multi-faceted approach from different systems of medicine. The purpose of this study was to evaluate whether homeopathically-potentized ultra-high dilutions of Lycopodium Clavatum (LC-5C and LC-15C, respectively) have any anti-cancer effects on HeLa cells. Cells were exposed to either LC-5C (diluted below Avogadro's limit, i.e., 10−10) or LC-15C (diluted beyond Avogadro's limit, i.e., 10−30) (drug-treated) or to 30% succussed ethanol (“vehicle” of the drug). The drug-induced modulation in the percent cell viability, the onset of apoptosis, and changes in the expressions of Bax, Bcl2, caspase 3, and Apaf proteins in inter-nucleosomal DNA, in mitochondrial membrane potentials and in the release of cytochrome-c were analyzed by utilizing different experimental protocols. Results revealed that administration of LC-5C and LC-15C had little or no cytotoxic effect in normal peripheral blood mononuclear cells, but caused considerable cell death through apoptosis in cancer (HeLa) cells, which was evident from the induction of DNA fragmentation, the increases in the expressions of protein and mRNA of caspase 3 and Bax, and the decreases in the expressions of Bcl2 and Apaf and in the release of cytochrome-c. Thus, the highly-diluted, dynamized homeopathic remedies LC-5C and LC-15C demonstrated their capabilities to induce apoptosis in cancer cells, signifying their possible use as supportive medicines in cancer therapy.