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Garg, Rishav,Garg, Rajni,Singla, Sandeep The Korean Electrochemical Society 2021 Journal of electrochemical science and technology Vol.12 No.4
Enhancement of durability and reduction of maintenance cost of concrete, with the implementation of various approaches, has always been a matter of concern to researchers. The integration of pozzolans as a substitute for cement into the concrete is one of the most desirable technique. Silica fume (SF) and colloidal nanosilica (CS) have received a great deal of interest from researchers with their significant performance in improving the durability of concrete. The synergistic role of the micro and nano-silica particles in improving the main characteristics of cemented materials needs to be investigated. This work aims to examine the utility of partial substitution of cement by SF and CS in binary and ternary blends in the improvement of the durability characteristics linked to resistance for electrochemical corrosion using electrical resistivity and half-cell potential analysis and chloride penetration trough rapid chloride penetration test. Furthermore, the effects of this silica mixture on the compressive strength of concrete under normal and aggressive environment have also been investigated. Based on the maximum compression strength of the concrete, the optimal cement substituent ratios have been obtained as 12% SF and 1.5% CS for binary blends. The optimal CS and SF combination mixing ratios has been obtained as 1.0% and 12% respectively for ternary blends. The ternary blends with substitution of cement by optimal percentage of CS and SF exhibited decreased rate for electrochemical corrosion. The strength and durability studies were found in consistence with the microstructural analysis signifying the beneficiary role of CS and SF in upgrading the performance of concrete.
Influence of pozzolans on properties of cementitious materials: A review
Garg, Rishav,Garg, Rajni,Eddy, Nnabuk Okon Techno-Press 2021 Advances in nano research Vol.11 No.4
Use of additives/supplementary materials in partial substitution of cement is gaining widespread attention across the world due to the sustainability issue with production of cement. With their pozzolanic activity & filler effect, use of nano-pozzolans such as nano-silica has been proved as quite promising & cost-effective for use as supplementary cementitious materials. This study is aimed at highlighting the effect of partial substitution of cement/addition of various nano-pozzolans on the hydration, strength and microstructure of the cementitious materials. Further, the effect of incorporation of other pozzolans has also been discussed. Comparative account of pozzolanic activity of different pozzolans has also been critically analyzed. It has been found that the cement matrix gets improved in terms of its microstructure by partial substitution of cement/addition of pozzolan in appropriate amount resulting in enhancement of the bulk properties by consumption of portlandite. The improved compressive strength of cementitious materials not only results in enhancement of the durability but also the service life of the construction structures and results in reduction of the cost incurred in maintenance and repair. Thus, the cement demand can be decreased by the partial substitution of cement/addition of such materials. It will result in an ultimate reduction of the greenhouse effect and lead to sustainable development.
Garg, M.R.,Gupta, B.N. Asian Australasian Association of Animal Productio 1993 Animal Bioscience Vol.6 No.3
Twenty male crossbred ($Sahiwal{\times}HF$) calves of about 6-9 months of age were divided into four groups of five animals each. All the animals were offered wheat straw ad lib. As the basal feed. However, animals in group I were fed concentrate mixture while the animals in groups II, III and IV had free access to urea molasses mineral block (UMMB) lick (I), (II) and (III) respectively as a partial substitute of concentrate mixture. The average concentrate offered (kg/day) to the animals was significantly (p<0.01) higher in group I ($2.69{\pm}0.18$) compared to groups II ($1.76{\pm}0.15$), III ($1.70{\pm}0.06$) and IV ($1.65{\pm}0.12$). The UMMB lick consumed was non-significantly different amongst groups I ($535.40{\pm}38.14$), II ($525.60{\pm}31.82$), III ($551.00{\pm}38.49$) and IV ($548.80{\pm}45.46$). Except ether extract, the digestibility coefficients of CP, ADF and NDF were non-significantly different in different groups. Similarly, N balance (g/day) and percent N retention of intake was not affected in different groups on supplementation of UMMB lick. Body composition of animals was similar in different groups supplemented with either concentrate mixture or concentrate mixture and UMMB licks. It may be concluded from these studies that UMMB lick can partially replace the concentrate mixture in the diet of growing calves without affecting the growth rate, nutrient utilization and body composition. The UMMB lick, thus, can form a part of the ration economically in the diet of growing ruminants especially in developing countries.
Seismic analysis of frame-strap footing-nonlinear soil system to study column forces
Garg, Vivek,Hora, Manjeet S. Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.5
The differential settlements and rotations among footings cannot be avoided when the frame-footing-soil system is subjected to seismic/dynamic loading. Also, there may be a situation where column(s) of a building are located near adjoining property line causes eccentric loading on foundation system. The strap beams may be provided to control the rotation of the footings within permissible limits caused due to such eccentric loading. In the present work, the seismic interaction analysis of a three-bay three-storey, space frame-footing-strap beam-soil system is carried out to investigate the interaction behavior using finite element software (ANSYS). The RCC structure and their foundation are assumed to behave in linear manner while the supporting soil mass is treated as nonlinear elastic material. The seismic interaction analyses of space frame-isolated footing-soil and space frame-strap footing-soil systems are carried out to evaluate the forces in the columns. The results indicate that the bending moments of very high magnitude are induced at column bases resting on eccentric footing of frame-isolated footing-soil interaction system. However, use of strap beams controls these moments quite effectively. The soil-structure interaction effect causes significant redistribution of column forces compared to non-interaction analysis. The axial forces in the columns are distributed more uniformly when the interaction effects are considered in the analysis.
Effect of Non-Idealities on the Design and Performance of a DC-DC Buck Converter
Garg, Man Mohan,Pathak, Mukesh Kumar,Hote, Yogesh Vijay The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3
In this study, the performance of a direct current (DC)-DC buck converter is analyzed in the presence of non-idealities in passive components and semiconductor devices. The effect of these non-idealities on the various design issues of a DC-DC buck converter is studied. An improved expression for duty cycle is developed to compensate the losses that occur because of the non-idealities. The design equations for inductor and capacitor calculation are modified based on this improved expression. The effect of the variation in capacitor equivalent series resistance (ESR) on output voltage ripple (OVR) is analyzed in detail. It is observed that the value of required capacitance increases with ESR. However, beyond a maximum value of ESR (r<sub>c,max</sub>), the capacitor is unable to maintain OVR within a specified limit. The expression of r<sub>c,max</sub> is derived in terms of specified OVR and inductor current ripple. Finally, these theoretical studies are validated through MATLAB simulation and experimental results.
Hyperosmotic polydixylitol for crossing the blood brain barrier and efficient nucleic acid delivery
Garg, P.,Pandey, S.,Seonwoo, Hoon,Yeom, Seungmin,Choung, Yun-Hoon,Cho, Chong-Su,Choung, Pill-Hoon,Hoon Chung, Jong The Royal Society of Chemistry 2015 Chemical communications Vol.51 No.17
<P>Here, we introduce a polydixylitol based highly osmotic polymer that not only transmigrates the BBB by intra-arterial infusion of osmotic polyol but also triggers cellular uptake <I>via</I> modulation of caveolae mediated endocytosis.</P> <P>Graphic Abstract</P><P>We report that the incorporation of a hyperosmotic molecule, dixylitol, into the backbone of a delivery vector can enhance its blood brain barrier transmigration. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc09871d'> </P>
Garg, M.R.,Gupta, B.N. Asian Australasian Association of Animal Productio 1992 Animal Bioscience Vol.5 No.3
Sixteen crossbred (Sahiwal $\times$ Holstein) male rumen fistulated calves of 18 to 24 months of age were randomly divided into four groups of four animal, each. Animals in all the groups were fed wheat straw ad lib as basal roughage. However, the animals in group I were fed concentrate mixture at maintenance level, whereas, the animals in groups II, III and IV had free access to existing, modified (A) and modified (B) urea molasses mineral block licks respectively. Daily wheat straw intake (kg) was significantly (p<0.01) higher in groups II ($4.20{\pm}0.13$), III ($4.07{\pm}0.16$) and IV ($4.22{\pm}0.20$) as compared to group I ($3.21{\pm}0.14$). Total N and TCA precistrained rumen liquor) was significantly higher in groups II ($22.36{\pm}0.25$), III ($21.63{\pm}0.25$) and IV ($21.77{\pm}0.55$) as compared to group I ($18.31{\pm}0.41$). Bacterial production rate (g/day and g/kg digestible organic matter intake) were non-significantly different amongst groups I ($214.4{\pm}13.28;\;85.38{\pm}3.69$); II ($198.7{\pm}5.70;\;86.17{\pm}3.53$); III ($214.4{\pm}8.19;\;96.15{\pm}2.16$) and IV ($218.2{\pm}10.62;\;94.44{\pm}5.52$). Similarly, percent efficiency of N incorporation into bacterial protein was not found significantly different amongst groups I, II, III and IV. These studies indicate that when concentrate mixture (upto maintenance level) in the diet of ruminants was replaced with UMMB licks, various N fraction in SRL and efficiency of bacterial production rates in the rumen were not affected.