Nripen Mondal

Bio: Nripen Mondal is an academic researcher from Jalpaiguri Government Engineering College. The author has contributed to research in topics: Bearing (mechanical) & Machining. The author has an hindex of 5, co-authored 12 publications receiving 67 citations. Previous affiliations of Nripen Mondal include Kalyani Government Engineering College & Jadavpur University.

Observation of Drilling Burr and Finding out the Condition for Minimum Burr Formation

Abstract: Suppression or elimination of burr formation at the exit edge of the workpiece during drilling is essential to make quality products. In this work, low alloy steel specimens have been drilled to observe burr height under different machining conditions. Taper shank, uncoated 14 mm diameter HSS twist drills are used in these experiments. Dry environment is maintained in experiment set I. Water is applied as cutting fluid in experiment set II. In the next four sets of experiments, the effect of providing back-up support material and exit edge bevel is observed on formation of burr at the exit edge of specimens under dry and wet conditions. It is revealed that an exit edge bevel of 31 degrees with water as the cutting fluid gives negligible burr at the exit edge of the drilled hole at certain machining conditions. Use of a back-up support can also reduce drill burr to a large extent. In this paper, artificial neural networks (ANN) are developed for modeling experimental results, and modeled values show close matching with the experimental results with small deviations.

Free radical scavenging property of Annona reticulata leaves

Abstract: SUMMARY Annona reticulata belonging to the family Annonaceae is traditionally used as anthelmintic and itis reported to have anticancer activity. Free radicals are known to be involved in various types ofdiseases like cancer, diabetes, neurological disorders etc. The present study was aimed to evaluatefree radical scavenging property of methanol extract of the leaves of Annona reticulata in some invitro models e.g. DPPH, nitric oxide, superoxide and lipid peroxide radical model. The extractshowed good dose-dependent free radical scavenging property in all the models. IC 50 values werefound to be 3.22, 170.01, 25.12 and 140.12 µg/ml respectively in DPPH, nitric oxide, superoxideand lipid peroxidation inhibition assays. Reductive ability of the extract was also tested based onpotassium ferricyanide reduction where dose dependant reducing capability was observed.Measurement of total phenolic compounds by Folin-Ciocalteu ’ s phenol reagent indicated that1mg of the extract contained 146.20 µg equivalent of pyrocatechol. The findings ascertainpromising free radical scavenging property of the extract and the antioxidant property of theextract may be due to the high content of phenolic compounds.Key words: Annona reticulata; Free radicals; Reductive ability; Phenolic compound

Scavenging activity of Curcuma caesia rhizome against reactive oxygen and nitrogen species

Abstract: Curcuma caesia Roxb. (Zingiberaceae), known as black turmeric in English, is a perennial herb found throughout the Himalayan region, North-East and Central India. The plant has been traditionally used in India for several medicinal purposes. Present study was carried out to evaluate the methanol extract of C. caesia (MECC) rhizome for some in vitro antioxidant studies as because we know that many diseases are associated with reactive oxygen species (ROS) and reactive nitrogen species (RNS). Effect of MECC on ROS and RNS were evaluated in different in vitro methods like 1, 1-diphenyl-2-picrylhydrazil radical, hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite and hypochlorous acid. Lipid peroxidation, total phenolic content was also measured by standard assay method. The extract showed significant antioxidant activities in a dose dependent manner. The IC50 values for scavenging of free radicals were 94.03 ± 0.67 μg/ml, 155.59 ± 3.03 μg/ml, 68.10 ± 1.24 μg/ml, 21.07 ± 1.78 μg/ml, 260.56 ± 12.65 μg/ml and 33.33 ± 0.52 μg/ml for DPPH, nitric oxide, superoxide, hydroxyl, peroxynitrite and hypochlorous acid respectively. Reductive ability of the extract was also tested where dose dependent reducing capability was observed. The rhizome extract contains 677.7 μg of phenolic compound in 10 mg of the extract which is accounted for its free radical as well as antioxidant activity. From the above study it is concluded that the methanol extract of C. caesia rhizome is a potential source of natural antioxidant.

Investigation of the effects of ultrasonic assisted drilling on tool wear and optimization of drilling parameters

Abstract: In this study, ultrasonic-assisted drilling was performed on different heat-treated (T6, T1) AA6061 to investigate the effects of cutting parameters on forces, surface roughness, and tool wear TiN-coated and uncoated HSS-G drill bits were used in the experiments The results obtained in the experiments were evaluated according to the general full factorial design and the effect graphs of different drilling parameters were generated In addition, ANOVA tables were created to evaluate the results SEM and OM micrographs were used to investigate the tool wear and chip formation Finally, a multi-response optimization was performed to optimize drilling parameters for minimum cutting force and surface roughness According to, optimum drilling parameters were determined as AA6061-T6 for material, uncoated HSS-G for a drill bit, 1520 rpm for spindle speed, and highest ultrasonic vibration frequency at 225 kHz In addition, it was observed that ultrasonic vibration has the effect of reducing built-up edge formation on the drill bit