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.

Experimental Investigation of Electrochemical Corrosion and Chloride Penetration of Concrete Incorporating Colloidal Nanosilica and Silica Fume

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.

CERTAIN INTEGRAL RELATIONS INVOLVING H-FUNCTION OF TWO VARIABLES

Garg, Om Prakash Department of Mathematics 1976 Kyungpook mathematical journal Vol.16 No.2

On Distribution of Order Statistics from Kumaraswamy Distribution

Garg, Mridula Department of Mathematics 2008 Kyungpook mathematical journal Vol.48 No.3

In the present paper we derive the distribution of single order statistics, joint distribution of two order statistics and the distribution of product and quotient of two order statistics when the independent random variables are from continuous Kumaraswamy distribution. In particular the distribution of product and quotient of extreme order statistics and consecutive order statistics have also been obtained. The method used is based on Mellin transform and its inverse.

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_c,max), the capacitor is unable to maintain OVR within a specified limit. The expression of r_c,max is derived in terms of specified OVR and inductor current ripple. Finally, these theoretical studies are validated through MATLAB simulation and experimental results.

Proline-based polymeric monoliths: Synthesis, characterization, and applications as organocatalysts in aldol reaction

Garg, Dipti,Ahn, J.-H.,Chauhan, Ghanshyam S. Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of polymer science Part A, Polymer chemist Vol.48 No.5

<P>Proline-based polymer monoliths were synthesized via green protocol using lipase-catalyzed esterification of methacrylic acid and 4-hydroxyproline. Prolinyl methacrylate thus prepared was polymerized in situ as crosslinked monolith. The monolith was characterized by various techniques such as Fourier transform infrared, <SUP>1</SUP>H-NMR, <SUP>13</SUP>C-NMR, scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen analysis and used as catalyst in aldol reactions. The swelling behavior of the monolith was also studied as function of various external parameters like pH and temperature. The monoliths synthesized with 1% crosslinker was selected as candidate monolith for use as catalyst in aldol reaction, which was studied as a function of time, temperature, substrate structure, and amount of water:EtOH. The catalysts exhibited high efficiency in the cross aldol reaction, especially with the aromatic substrates having electron withdrawing substituent, and also good activity retention was observed when recycleability was studied up to five cycles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1007–1015, 2010</P> <B>Graphic Abstract</B> <P>Proline-based polymer monoliths were synthesized via green protocol using lipase-catalyzed esterification of methacrylic acid and 4-hydroxyproline. The monomer was polymerized to polymer monoliths, and the latter were used as heterogeneous polymer catalysts in the aldol reaction that was studied in three forms viz. simple aldol, cross aldol, and ketone-aldehyde reaction. The catalysts exhibited high efficiency in the cross aldol reaction, especially with the aromatic substrates having electron withdrawing substituent, and reasonable retention of catalytic efficiency up to five cycles. <img src='wiley_img/0887624X-2010-48-5-POLA23845-gra001.gif' alt='wiley_img/0887624X-2010-48-5-POLA23845-gra001'> </P>

Giant Duplication Cyst Presenting as a Discharging Umbilicus

Garg, Ravi Kumar,Bawa, Monika,Rao, Katragadda Lakshmi Narasimha The Korean Society of Pediatric Gastroenterology 2017 Pediatric gastroenterology, hepatology & nutrition Vol.20 No.3

Alimentary tract duplication cysts are rare congenital anomalies, most commonly located in the ileum, but may present anywhere from mouth to anus.Clinically, they may be asymptomatic, incidentally diagnosed or may present with obstruction, volvulus, intussusception or gastrointestinal bleed. Here we report a case of a one year old male child presenting in gasping state and shock. Despite the initial strong suspicion of Meckel's diverticulum and tubercular abdomen, the final diagnosis remained elusive till exploratory laparotomy was performed which revealed a duplication cyst of ileum with perforation into the umbilicus. Duplication cyst should always be kept as a differential diagnosis so that early intervention can help in better management.

Blunt Trauma Pancreas in Children: Is Non-Operative Management Appropriate for All Grades?

Garg, Ravi Kumar,Mahajan, Jai Kumar The Korean Society of Pediatric Gastroenterology 2017 Pediatric gastroenterology, hepatology & nutrition Vol.20 No.4

Purpose: Blunt trauma of pancreas in children is uncommon and its management varies from observational to early operative intervention. We analysed the feasibility and outcome of non-operative management in all grades of paediatric pancreatic injuries. Methods: A total of 15 patients of pancreatic trauma seen in a Paediatric Surgery Unit were retrospectively analyzed. Results: Age of the patients ranged from 3-11 years (mean, 7.7 years). The mode of injury was local trauma in 9 children. Only 3 patients had associated injuries and all were haemodynamically stable. Serum amylase levels were raised in 12 patients at admission which ranged from 400-1,000 IU. Computed tomography scan made a correct diagnosis in 14 patients. Grades of the injury varied from grade I-V (1, 3, 6, 4, 1 patients respectively). Fourteen patients were managed conservatively. One patient underwent laparotomy for suspected superior mesenteric hematoma. The average duration of enteral feeds was 3.7 days and of hospital stay was 9.4 days. Six patients formed pancreatic pseudocysts; two were managed conservatively while the other four underwent cystogastrostomy. The patients were followed up for a period of 1-12 years. All remained asymptomatic and none had exocrine or endocrine deficiencies. Conclusion: Non-operative treatment for isolated blunt trauma of pancreas in children may be safely followed for all the grades of injury; if associated injuries requiring surgical intervention are ruled out with a good quality imaging and the patients are hemodynamically stable. It did not increase the hospital stay and morbidity and avoided operative intervention on acutely injured pancreas.

Bending analysis of power-law sandwich FGM beams under thermal conditions

Garg, Aman,Belarbi, Mohamed-Ouejdi,Li, Li,Tounsi, Abdelouahed Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.3

Broad writing on the examination of sandwich structures mirrors the significance of incorporating thermal loadings during their investigation stage. In the current work, an endeavor has been made to concentrate on sandwich FGM beams' bending behaving under thermal loadings utilizing shear deformation theory. Temperature-dependent material properties are used during the analysis. The formulation includes the transverse displacement field, which helps better predict the behavior of thick FGM beams. Three-different thermal profiles across the thickness of the beam are assumed during the analysis. The study has been carried out on both symmetric and unsymmetric sandwich FGM beams. It has been observed that the bending behavior of sandwich FGM beams is impacted by the temperature profile to which it is subjected. Power-law exponent and thickness of core also affect the behavior of the beam.

JNK2 silencing and caspase-9 activation by hyperosmotic polymer inhibits tumor progression

Garg, Pankaj,Pandey, Shambhavi,Hoon, Seonwoo,Jang, Kyoung-Je,Lee, Myung Chul,Choung, Yun-Hoon,Choung, Pill-Hoon,Chung, Jong Hoon Elsevier 2018 International journal of biological macromolecules Vol.120 No.2

<P><B>Abstract</B></P> <P>c-Jun N-terminal kinase 2 (JNK2) is primarily responsible for the oncogenic transformation of the transcription factor c-Jun. Expression of the proto-oncogene c-Jun progresses the cell cycle from G1 to S phase, but when its expression becomes awry it leads to uncontrolled proliferation and angiogenesis. Delivering a JNK2 siRNA (siJNK2) in tumor tissue was anticipated to reverse the condition with subsequent onset of apoptosis which predominantly requires an efficient delivering system capable of penetrating through the compact tumor mass. In the present study, it was demonstrated that polymannitol-based vector (PMGT) with inherent hyperosmotic properties was able to penetrate through and deliver the siJNK2 in the subcutaneous tumor of xenograft mice. Hyperosmotic activity of polymannitol was shown to account for the enhanced therapeutic delivery both in vitro and in vivo because of the induction of cyclooxygenase-2 (COX-2) which stimulates caveolin-1 for caveolae-mediated endocytosis of the polyplexes. Further suppression of JNK2 and hence c-Jun expression led to the activation of caspase-9 to induce apoptosis and inhibition of tumor growth in xenograft mice model. The study exemplifies PMGT as an efficient vector for delivering therapeutic molecules in compact tumor tissue and suppression of JNK2 introduces a strategy to inhibit tumor progression.</P> <P><B>Graphical abstract</B></P> <P>Hyperosmotic PMGT driven siJNK2 delivery in compact cancer cells inhibits c-jun phosphorylation resulting in tumor growth arrest via caspase-9 induction and apoptosis.</P> <P>[DISPLAY OMISSION]</P>