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Sekhon, Satpal Singh,Park, Jin-Soo,Choi, Young-Woo Royal Society of Chemistry 2010 Physical Chemistry Chemical Physics Vol.12 No.41
<P>Small-angle X-ray scattering (SAXS) technique has been used to study the evolution of ionomer peak in the recast Nafion membranes containing the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF<SUB>4</SUB>). To the best of our knowledge, this is the first report dealing with the study of membranes containing different concentrations of the ionic liquid (EMIBF<SUB>4</SUB>), from the dry (no ionic liquid) to the saturation (containing 70 wt% ionic liquid) state to understand the evolution of the ionomer peak and the formation of ionic aggregates in these anhydrous membranes. The small-angle scattering maximum (ionomer peak) has been observed to shift continuously toward lower scattering vector (<I>q</I>) values as the ionic liquid content increases. The ionic conductivity behavior for the membranes containing ionic liquid has been found to be closely related with the change of slope of the double logarithmic plot between the reciprocal of the position of the ionomer peak and the polymer weight fraction. The <I>q</I> region over which Porod's law has been obeyed in different membranes was initially narrow and has been observed to widen with an increase in the content of the ionic liquid.</P> <P>Graphic Abstract</P><P>Ionomer peak shifts to lower scattering vector values with an increase in ionic liquid content in anhydrous fuel cell membranes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cp00966k'> </P>
고온/저가습 고분자전해질 연료전지를 위한 이온성 액체 기반 고분자 전해질막 개발
새트팔 싱 세콘(Satpal Singh Sekhon),박진수(Jin-Soo Park),조은경(EunKyung Cho),박구곤(Gu-Gon Park),김창수(Chang-Soo Kim),이원용(Won-Yong Lee) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
High temperature polymer electrolyte membranes incorporating ionic liquids (ILs) in different polymers such as commercial fluorinated polymers, sulfonated polymers and recasted nafion have been developed. ILs based on imidazolium cation and different anions possess high ionic conductivity and good thermal stability and have been used in the present study. The membranes containing IL show conductivity ~10-2 S cm-1 above 100oC under anhydrous conditions and are thermally stable up to 250-300 oC. IL acts as a conducting medium in these electrolytes and plays the same role as played by water in fully hydrated nafion membranes. Due to high conductivity and good thermal stability, these membranes are promising materials for PEFCs at higher temperatures under anhydrous conditions.
A Comparative Study of AA6351 Mono-Composites Reinforced with Synthetic and Agro Waste Reinforcement
Gaurav Arora,Satpal Sharma 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.4
The use of industrial-agro wastes as reinforcements in the development of composites can be considered as a new inclination in the field of material research. The present investigation involves the development of AA6351 mono-composites with various weight percentages (2wt.%, 4wt.%, 6wt.% and 8wt.%) of silicon carbide (SiC) and rice husk ash (RHA) as reinforcement using stir casting technique. The physical, microstructural, mechanical and tribolological behaviour of the developed composites were examined for the both type of the composites. An increase of 1.08% in density, 37% in hardness and 39% in tensile strength was recorded for the composites developed with silicon carbide as reinforcement and a decrease in density of 3.9%, an improvement of 16% in hardness and 21% in tensile strength was indicated for the composites reinforced with rice husk ash as reinforcement. The results also revealed a uniform distribution of the reinforcement and improved wear resistance for the both set of the composites. The characterization results exhibited that even the performance of the composites with SiC as reinforcement is better than the performance of the composites with RHA as reinforcement but RHA can be suitably applied as reinforcement for the development of low density AA6351/RHA green composites.
Bioengineered aptamer-nanoconjugates for cancer theragnosis
SEKHONSIMRANJEET SINGH,안근아,Satpal Singh Sekhon,Ji-Young Ahn,Yang-Hoon Kim 대한독성 유전단백체 학회 2018 Molecular & cellular toxicology Vol.14 No.4
Early detection and treatment of cancer is of global interest as cancer is one of the leading causes of death worldwide. As the survival rate of cancer patients is closely related to its detection at an early stage, there is an urgent need to develop detection techniques that are fast, reliable, and easily available. Aptamers are single stranded DNA- and RNA- based oligonucleotides that can bind to their targets with high affinity and specificity. Their small size, excellent chemical stability, and low immunogenicity enable them to become alternatives to antibodies in cancer theragnostic approaches with cancer imaging and therapy applications. Purpose of review: In this review, we discuss the role of aptamer-nanomaterials conjugates as novel molecular tools for enhanced diagnosis (biosensing and nano-imaging) and therapy (drug delivery) of cancer cells.
Shashi Prakash Dwivedi,Satpal Sharma,Raghvendra Kumar Mishra 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.10
Three AA2014 alloy metal matrix composites containing reinforcing particles of eggshell, carbonized eggshell and CaCO3 (powder) were processed. The influences of different particle percentage of eggshell were compared with commercial calcium carbonate. The electromagnetic stir casting technique followed by hot extrusion was employed to fabricate metal matrix composite. The results revealed that the tensile strength, hardness and fatigue strength increased by the addition of eggshell particles up to 12.5 wt.% in AA2014 matrix alloy for both carbonized and uncarbonized reinforced composites. Toughness, ductility and corrosion rate decreased by the addition of eggshell particles up to 12.5 wt.% in AA2014 matrix alloy for both carbonized and uncarbonized reinforced composites. Mechanical properties decreased in the addition CaCO3 in AA2014 matrix alloy. After the heat treatment process, mechanical properties further improved for both carbonized and uncarbonized eggshell particles reinforced composites. However, corrosion rate increased. These results showed that using the carbonized eggshell as reinforcement in the AA2014 alloy gave better physical and mechanical properties at lower cost as compared to uncarbonized ES particles and CaCO3. Apparent interfacial reaction layer and minimum corrosion were observed at AA2014/12.5% carbonized eggshell particulate composite. No reaction product was observed at AA2014/CaCO3 particulate metal matrix composite.
Shashi Prakash Dwivedi,Satpal Sharma,Raghvendra Kumar Mishra 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.3 No.3
Chicken eggshell (ES) is an aviculture byproduct that has been listed worldwide as one of the worst environmental problems. The effective utilization of chicken eggshell (ES) biowaste is strongly encouraged in our society for environmental and economic reasons. The present work deals with development of AA2014/ carbonized eggshells particulate composites by electromagnetic stir casting process at optimized parameters using RSM. The predicted tensile strength of 239 MPa of the composite was found at optimum parameters of 60 MPa (Squeezing Pressure), 12 ampere (Current), 180 s (Time) and 700oC (Pouring Temperature) respectively. There was about 2.79% error in the experimental and modeled results of tensile strength. Obtained result shows that as stirring current and stirring temperature increases, tensile strength also increases. While increase in pouring temperature of matrix decreases tensile strength of composite. Density of the metal matrix composite decreases 5%, when eggshells particulate is added 5% by wt. to matrix alloy. Hardness, toughness and fatigue strength were also carried out of the AA2014/eggshell composite. Results show an improvement in these properties with the addition of eggshell in the matrix alloy. Microstructural study show uniform distribution of eggshell in the composites.
Prabhsharan Kaur,김다은,Gaurav Verma,박진수,Satpal Singh Sekhon 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.96 No.-
The surface modification of carbon nanomaterials with heteroatoms improves their electrocatalyticactivity for oxygen reduction reaction (ORR). The present work reports the surface modification ofcarbon nanofiber (CNF) with poly(diallyldimethylammonium) chloride (PDDA) and Triton X-100. PDDAbehaves as an electron-acceptor, and the intermolecular charge transfer from CNF to PDDA createsdelocalized positive charge sites at the edge and basal plane sites of CNF. Triton X-100 disperses CNF,but also acts as a masking agent to obstruct the intermolecular charge transfer between CNF and PDDA. The surface modification of CNF with (PDDA + Triton X-100) is characterized in terms of FESEM, TEM,EDX, Raman, FTIR and TGA. The electrocatalytic activity of the conjugated systems (CNF + PDDA andCNF + Triton X-100+PDDA) is investigated in terms of cyclic voltammetry and linear sweepvoltammetry. The reduction of oxygen at PDDA-CNF occurs via a more efficient four-electron(n = 3.9) pathway in 0.1 M KOH and exhibits a limiting diffusion current density of 3.23 mA cm 2, whichis closer to the Pt/C electrode (3.41 mA cm 2). PDDA-CNF even outperforms PDDA-CNT or graphene forthe ORR performance owing to their special morphological features. This study thus provides a facileand viable strategy for the scalable production of CNF based ORR electrocatalysts.
Tae-Yeon Cho,Kwan-Woo Ko,윤순길,Satpal Singh Sekhon,강만구,Young-Sik Hong,한치환 한국물리학회 2013 Current Applied Physics Vol.13 No.7
We investigated the effect of a Nb2O5 blocking layer formed through the solegel method introduced to a titanium metal foil electrode in a flexible dye sensitized solar cell. The blocking layer formed directly on the working electrode physically separates the working electrode from the electrolyte, and prevents back transfer of electrons from the electrode to the electrolyte. The gel processing conditions (sol reaction time) and heat treatment temperature used in formation of the Nb2O5 blocking layer have been shown to affect the performance of the dye sensitized solar cell and optimal values of these parameters have been determined. A sol reaction time of 45 min and heat treatment temperature of 550 ℃ has been observed to result in optimal cell performance (h = 6.185%, Jsc = 13.233 mA/cm2, Voc = 0.672 V, ff = 0.694). Introduction of an Nb2O5 blocking layer enhances solar cell efficiency by 39.7%, which is much greater than the increase of 24.6% observed in a similar cell containing a TiO2 blocking layer under standard illumination conditions. The results obtained via Nb2O5 have been observed to be superior to those obtained via a TiO2 blocking layer.