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- 검색키워드
- 저자 : Chatha, S.A. (검색결과 4 건)
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Amrit Pal,Sukhpal Singh Chatha,Hazoor Singh Sidhu 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.3
Due to rising attention towards environmental and ecological issues caused by mineral oil-based lubricants in machining operations, the developing of an environmental favourable lubricant has become inevitable. As environmental favourable cutting fluids, vegetable oils have acquired great attention in machining operations due to their good biodegradability, nontoxicity and less environmental pollutant properties. Nowadays, the minimum quantity lubrication (MQL) technique is explored as alternative technique to conventional flood cooling technique. However, very limited work is done to investigate the effect of MQL technique using vegetable oils as the base oil for machining of hard materials. Moreover, systematic comparison of different vegetable oils as the base oil will be of great significance to the manufacturing industry. Therefore, in this study, the performance of six vegetable oils viz. castor, coconut, soybean, canola, palm and sunflower oil, and distilled water has been investigated during drilling of stainless steel (AISI 321) using minimum quantity lubrication technology. The main objective of this study is to compare the performance of various cooling strategies viz. dry, flood and seven MQL conditions with respect to drilling characteristics (thrust force, torque, surface roughness, coefficient of friction (COF), chip morphology and wear mechanism) in the drilling of stainless steel (AISI 321) by using HSS drill tools. Experimental findings showed that MQL drilling conditions have given excellent drilling performance by improving drilling characteristics than dry and flood drilling. Among the MQL fluids, sunflower oil provided better lubrication and improved the drilling characteristics followed by palm, canola, soybean, coconut, castor oil and distilled water. Sunflower oil had a thrust force, torque, surface roughness and coefficient of friction of 1425 N, 22.8 Nm, 4.356 μm and 4.000 μ, which reduced by 21.27%, 25.49%, 30.72% and 5.35%, respectively than that under flood drilling at 30th hole. The better lubrication performance of sunflower oil may be attributed to the rich presence of saturated-fatty acids. In addition, vegetable oils based MQL technique is more worthy to improve the cooling capabilities and promote sustainability in the manufacturing sector by saving resources and extending environmental benefits.
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Nasir Shabab,Walters Keith F.A.,Pereira Roberto M.,Waris Muhammad,Ali Chatha Awais,Hayat Munawar,Batool Marriam 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.3
Mosquito vectors of major human diseases are currently controlled using chemical and biological products. Extensive insecticide use has led to resistance development and human/environmental health risks, and alter native sustainable control options are needed; in this study, activity of an extract of garlic (Allium sativum; Amaryllidaceae), and silver nanoparticles (AgNPs) synthesized from the extract, were evaluated against 2nd and 3rd instar larvae of the yellow fever mosquito, Ae. aegypti (Diptera: Culicidae). Synthesis of AgNPs was confirmed using UV–Vis spectroscopy, and characterised using powdered X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Larvae were exposed to five concentrations (50, 100, 150, 200, 250 ppm) of garlic extract or synthesized AgNPs, with distilled water and silver nitrate solution (1 mM) as controls. The mortality of larvae was recorded after 6, 12, 24, 36, and 48 h following addition of the respective extracts. Dose- and time-dependent toxicity were recorded in both treatment groups with no mortality in control groups. Exposure to AgNPs at 250 ppm for 48 h yielded 100% mortality for both larval instars, with corre sponding LC 50 values of 44.77 (2nd) and 62.82 ppm (3rd). Exposure to garlic extract resulted in similar 48-hour mortality (99 ± 0.77% (2nd) and 98 ± 1.10% (3rd), but consistently higher LC 50 values after all exposure times compared to AgNPs (e.g. 48-hour exposure: 108.42 ppm (2nd), 129.11 ppm (3rd), suggesting that AgNPs may potentially be used at lower concentrations for Ae. aegypti control.
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Prion Protein Genotypes in Pakistani Goats
Babar, M.E.,Nawaz, M.,Nasim, A.,Abdullah, M.,Imran, M.,Jabeen, R.,Chatha, S.A.,Haq, A.U.,Nawaz, A.,Mustafa, H.,Nadeem, A. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.7
The PCR-amplified prion protein (PrP) gene was sequenced to determine the frequency of scrapie-associated as well as novel PrP genotypes in 72 healthy goats representing five breeds. A total of six genotypes were detected, resulting from the three reported 143 (H/R), 154 (R/H) and 240 (S/P) and the two novel 39 (S/R) and 185 (I/F) amino acid polymorphisms. Of the four silent mutations 42 (a$\rightarrow$g), 138 (c$\rightarrow$t), 231 (c$\rightarrow$a) and 237 (g$\rightarrow$c) detected in this study, 237 (g$\rightarrow$c) is novel. A genotype (SIP/RFP) harboring three amino acid polymorphisms 39 (S/R), 185 (I/F) and 240 (S/P) was found in few goats. Although both scrapie-associated genotypes with 143 (H/R) and 154 (R/H) polymorphisms and others with 39 (S/R), 185 (I/F) and 240 (S/P) polymorphisms were present in the studied Pakistani goats, their frequency was lower than that of the wild-type genotype SHRIS/SHRIS (34.7%). These results emphasize the need for further sequencing of the PrP gene in a large number of goats representing the five studied breeds, so that overall PrP variability can be assessed in these breeds in research addressing future concerns about scrapie.
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Muhammad Fiayaz,Khalid Mahmood Zia,Muhammad Asif Javaid,Saima Rehman,Shahzad Ali Shahid Chatha,Mohammad Zuber 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12
A novel green series of hydroxyethyl cellulose (HEC) based polyurethane (PUs) prepolymersblended with TiO2 nanoparticles were synthesized by reaction of Isophorone diisocyanate (IPDI), hydroxyl-terminated polybutadiene (HTPB), and hydroxyethyl cellulose (HEC). The chain was further extended with 1,4-butanediol (BDO) to get final HEC based polyurethane bio nanocomposites (FPUNC). A mixture of HEC based polymer and TiO2 nanoparticles was formed in solution polymerization, in which the TiO2 nanoparticles dispersed depending on interaction of TiO2 nanoparticles with polymer chains. The molecular structure of the synthesized PU bionanocomposites was confirmed by FTIR. A series of FPUNCs was prepared by varying the percent composition of the TiO2 nanoparticles into the PU matrix. The morphology of the bionanocomposites was carried out by X-ray diffraction (XRD) studies and scanning electron microscopy (SEM). SEM images verified the good dispersion of TiO2 nanoparticles into PU matrix. The thermal stability of the synthesized FPUNCs was done by thermal gravimetric analysis (TGA), and the FPUNC12 with 5% contents of TiO2 nanoparticles showed better thermal stability. The resultant HEC-TiO2 based FPUNCs material have promising bio-degradable and bio functional materials with good thermal properties and have potential applications in the field of biomaterials.
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