Comparison of the proton irradiation-induced damage in SiC_f/SiC with Sc-nitrate and Al₂O₃-Y₂O₃ sintering additives

Sharma, Amit Siddharth,Fitriani, Pipit,Min, Bong-Ki,Yoon, Dong-Hyok Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.7

<P><B>Abstract</B></P> <P>We report microstructural evaluation in proton-irradiated SiC<SUB>f</SUB>/SiC up to a fluence level of 10<SUP>18</SUP> p<SUP>+</SUP>/m<SUP>2</SUP> (E = 20 MeV) performed at the Korea Multi-purpose Accelerator Complex (KOMAC). To fabricate the SiC<SUB>f</SUB>/SiC, a SiC-based matrix with two different sintering additives, Sc-nitrate and Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB>, were infiltrated into the Tyranno<SUP>®</SUP> SiC preform by electrophoretic deposition and subsequent hot pressing. Scanning (SEM) and high resolution (HREM) electron microscopy was used to probe crack formation, pore generation and surface amorphization upon irradiation. SiC matrix was comparatively more crack-resistant in the SiC<SUB>f</SUB>/SiC with Sc-nitrate than that with Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB>. Subsurface porosity evolved in the form of continuous bands for Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB> and discrete pockets for Sc-nitrate additives. Selective leaching of Si from the grain surface leads to the formation of a graded structure and surface amorphization. Irradiation-induced roughness on the fibers facilitates easy debonding at the SiC<SUB>f</SUB>-PyC<SUB>coating</SUB> interface but no significant changes in the flexural behavior were observed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SiC<SUB>f</SUB>/SiC with Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB> and Sc-nitrate sintering additives were proton irradiated. </LI> <LI> Formation of micro-scale (surface cracks, subsurface porosity) and nano-scale (black spot defects and amorphization) defects were qualitatively compared. </LI> <LI> Irradiated composites showed extensive fiber-coating debonding but overall behavior was almost similar. </LI> <LI> SiC<SUB>f</SUB>/SiC with Sc-nitrate addition is more irradiation resistant than that with Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB> addition. </LI> </UL> </P>

Targeting Heterogeneous Tumors Using a Multifunctional Molecular Prodrug

Sharma, Amit,Lee, Min-Goo,Won, Miae,Koo, Seyoung,Arambula, Jonathan F.,Sessler, Jonathan L.,Chi, Sung-Gil,Kim, Jong Seung American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.39

<P>Reported here is a molecular construct (<B>K1</B>) designed to overcome hurdles associated with delivering active drugs to heterogeneous tumor environments. Construct <B>K1</B> relies on two cancer environment triggers (GSH and H<SUB>2</SUB>O<SUB>2</SUB>) to induce prodrug activation. It releases an active drug form (SN-38) under conditions of both oxidative and reductive stress <I>in vitro</I>. Specific uptake of <B>K1</B> in COX-2 positive aggressive colon cancer cells (SW620 and LoVo) was seen, along with enhanced anticancer activity compared with the control agent SN-38. These findings are attributed to environmentally triggered drug release, as well as simultaneous scavenging of species giving rise to intracellular redox stress. <B>K1</B> serves to downregulate various cancer survival signaling pathways (AKT, p38, IL-6, VEGF, and TNF-α) and upregulate an anti-inflammatory response (IL-10). Compared with SN-38 and DMSO as controls, <B>K1</B> also displayed an improved <I>in vivo</I> therapeutic efficacy in a xenograft tumor regrowth model with no noticeable systematic toxicity at the administrated dose. We believe that the strategy described here presents an attractive approach to addressing solid tumors characterized by intratumoral heterogeneity.</P> [FIG OMISSION]</BR>

Ion beam induced modifications in nitroso substituted polyaniline: Spectral and electrical studies

Amit L. Sharma,Alok Srivastava 한국물리학회 2007 Current Applied Physics Vol.7 No.6

The eects of ion beam irradiation on optical, chemical and electrical properties of nitroso substituted polyaniline, polynitrosoaniline(N-PANI) have been investigated. N-PANI was irradiated with 100 MeV28Si ions at dierent ion-uences. The pristine and irradiatedpolymer samples were characterized by FT-IR, UVvisible spectroscopic techniques. The electrical conductivity studies were conductedon polymer samples. A signicant change in optical band gap and room temperature electrical conductivity was observed in polymersamples after irradiation. The solubility of the polymer samples has also been tested in 1-methyl-2-pyrrolidone (NMP).

Intravesical Migration of an Intrauterine Contraceptive Device with Secondary Calculus Formation

Amit Sharma,Mukund Andankar,Hemant Pathak 대한가정의학회 2017 Korean Journal of Family Medicine Vol.38 No.3

Intrauterine contraceptive devices (IUCDs) are a common form of reversible contraception owing to fewer system-ic side effects and low cost, especially in a developing country like India. However, IUCDs are not without compli-cations. Migration of a device into adjacent organs is the most morbid of all the documented complications. A pa-tient who presents with a history that suggests loss or disappearance of an IUCD thread associated with urinary symptoms should raise suspicions that a device may have migrated into the bladder. Physicians should also be aware of possible secondary vesical calculus formation. Further radiological investigations and appropriate man-agement are warranted. We present a case report describing the migration of an IUCD into the bladder with sec-ondary calculus formation.

Fabrication of SiC_f/SiC and integrated assemblies for nuclear reactor applications

Sharma, Amit Siddharth,Fitriani, Pipit,Yoon, Dang-Hyok Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.18

<P><B>Abstract</B></P> <P>This study examined the processing feasibility of electrophoretic deposition (EPD), as an effective matrix infiltration method, in conjunction with hot-pressing to fabricate dense and tough SiC<SUB>f</SUB>/SiC materials. Flat and tubular specimens were fabricated by hot pressing at 1750°C and 20MPa after infiltrating a SiC-based matrix phase into Tyranno<SUP>®</SUP> SA3 SiC fabrics, which can be used as the core structural components for the next generation fission reactors and as blanket materials for future fusion reactors. For the tubular specimens, two types of preforms were compared: filament wound and jelly-rolled with different woven structures. The incorporation of SiC green tapes between the successive layers of SiC fabrics allowed better control over the composite density and pore distribution. The macro-architecture of the composites was optimized in terms of the slurry composition, sintering additives, and phase evolution. Fractography revealed considerable debonding at the SiC<SUB>fiber</SUB>-PyC<SUB>coating</SUB> interface and fiber pull-out with pronounced tail extension behavior when tested in flexure. Joining of the flat-tube and flat-flat SiC<SUB>f</SUB>/SiC was performed using a range of filler systems; the structures integrated using the Ti-based MAX fillers at 1750°C and 3.5MPa for 1–2h soaking time are discussed.</P>

Molecular Characterization of Rathi and Tharparkar Indigenous Cattle (Bos indicus) Breeds by RAPD-PCR

Sharma, Amit Kumar,Bhushan, Bharat,Kumar, Sanjeev,Kumar, Pushpendra,Sharma, Arjava,Kumar, Satish Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.9

Random amplification of polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) analysis was carried out using DNA samples of 30 animals of Rathi cattle and 42 animals of Tharparkar cattle. Genomic DNA was isolated as per standard protocol and evaluated for its quality, purity and concentration. Twenty three random primers were screened out of which 15 primers yielded satisfactory amplifications and were used for further analysis. Average numbers of polymorphic fragments per primer were 7.07${\pm}$0.86 in Rathi and 6.80${\pm}$0.61 in Tharparkar cattle. The percentage of polymorphic bands in these two cattle breeds were 86 and 87%, respectively. Within breed genetic similarities for pooled over primers in the animals of Rathi and Tharparkar breeds were .577${\pm}$0.30 and 0.531${\pm}$0.02, respectively on the basis of band frequency (BF) and 0.645${\pm}$0.04 and 0.534${\pm}$0.04, respectively on the basis of band sharing (BS). Averages of between breed genetic similarities for pooled over primers were 0.97 and 0.92 according to BF and BS, respectively, which reflect higher degree of genetic similarity between Rathi and Tharparkar cattle breeds. Index of genetic distance based on BF and BS for pooled over primers was 0.030${\pm}$0.011 and 0.088${\pm}$0.031, respectively. Percentage of polymorphic bands and within-breed genetic similarities on the basis of band frequency (BF) and band sharing (BS) for pooled over primers revealed higher genetic similarity in Rathi than Tharparkar cattle population. High estimates of between breed genetic similarities for pooled over primers indicated that either Rathi is having decent from Tharparkar or both the cattle breeds are having common descent. Low value of Index of genetic distances between these two cattle breeds may be due to the fact that Rathi and Tharparkar cattle breeds are the native of Thar Desert in Northwest India. The results of between breed genetic distances also confirm the existence of high degree of genetic similarity between these two breeds of cattle.

Molecular theranostic based on esterase-mediated drug activation for hepatocellular carcinoma

Sharma, Amit,Kim, Eun-Joong,Mun, Seokgyu,Ji, Myung Sun,Chung, Bong Geun,Kim, Jong Seung Elsevier 2019 Dyes and pigments Vol.163 No.-

<P><B>Abstract</B></P> <P>In past few years, cancer specific targeted drug formulations have shown some hope of improving the therapeutics with minimized associated side effects of chemotherapy. However, the benefits has proven modest due to lack of systems that can be assessed easily from parent drugs while maintaining the same features of cancer associated prodrug activation. We developed a small molecule-based, carboxylesterase responsive theranostic, <B>EDOX</B>, with tumor-specific enzymatic activation for targeted delivery of the anticancer drug, Doxorubicin (Dox), to hepatocellular carcinoma (HCC) cells. Easy synthetic access, physiological stability, tumor-selective activation, and sustained drug release make <B>EDOX</B> an excellent candidate for use as a next-generation drug delivery system for HCC.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A small molecular theranostic <B>EDOX</B> has been developed. </LI> <LI> <B>EDOX</B> exhibits carboxylesterase responsive activation in HCC cancer cell line specifically. </LI> <LI> Theranostic <B>EDOX</B> exhibits “turn on” fluorescence enhancement response with activation. </LI> <LI> Easier synthetic access with cancer selective activation makes <B>EDOX</B> as potential candidate in future clinical application. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A cancer associated carboxylesterase responsive bifunctional prodrug (<B>EDOX</B>) was developed to provide hepatocellular carcinoma (HCC) specific drug delivery and real-time monitoring of drug distribution.</P> <P>[DISPLAY OMISSION]</P>

A review on the mechanical properties of polymer composites reinforced by carbon nanotubes and graphene

Amit Kumar,Kamal Sharma,Amit Rai Dixit 한국탄소학회 2021 Carbon Letters Vol.31 No.2

Compared to carbon nanotubes (CNTs), graphene possesses high strength due to wrinkled surface texture caused by a high density of surface defects which benefits more contact with the polymer material than a rolled-up CNT. In the present review, we have discussed and compared the various properties of CNTs (1-D) and graphene (2-D) obtained in experimental results. The effects of covalent and non-covalent functionalization of CNTs and graphene on the properties of its composites have also been reviewed and compared. A comparative analysis has been carried out between CNTs and graphene-reinforced polymer composites. Furthermore, the synergetic effects of CNTs and graphene hybrid nanofiller on the mechanical properties of polymer composites have also been briefly discussed. Finally, this review concludes with the potential application and future challenges are discussed with regards to filler and their polymer composites.

Special issue on the human microbiome: from symbiosis to therapy

SHARMA AMIT KUMAR,임신혁 생화학분자생물학회 2020 Experimental and molecular medicine Vol.52 No.-

Development of a theranostic prodrug for colon cancer therapy by combining ligand-targeted delivery and enzyme-stimulated activation

Sharma, Amit,Kim, Eun-Joong,Shi, Hu,Lee, Jin Yong,Chung, Bong Geun,Kim, Jong Seung Elsevier 2018 Biomaterials Vol.155 No.-

<P><B>Abstract</B></P> <P>The high incidence of colorectal cancer worldwide is currently a major health concern. Although conventional chemotherapy and surgery are effective to some extent, there is always a risk of relapse due to associated side effects, including post-surgical complications and non-discrimination between cancer and normal cells. In this study, we developed a small molecule-based theranostic system, <B>Gal-Dox</B>, which is preferentially taken up by colon cancer cells through receptor-mediated endocytosis. After cancer-specific activation, the active drug <B>Dox</B> (doxorubicin) is released with a fluorescence turn-on response, allowing both drug localization and site of action to be monitored. The therapeutic potency of <B>Gal-Dox</B> was also evaluated, both <I>in vivo</I> and <I>ex vivo</I>, thus illustrating the potential of <B>Gal-Dox</B> as a colorectal cancer theranostic with great specificity.</P> <P><B>Graphical abstract</B></P> <P>Herein, we developed a small molecule-based theranostic system, <B>Gal-Dox</B>, which is preferentially taken up by colon cancer cells through receptor-mediated endocytosis. After cancer-specific activation, the active drug <B>Dox</B> (doxorubicin) is released with a fluorescence turn-on response, allowing both drug localization and site of action to be monitored. The therapeutic potency of <B>Gal-Dox</B> was also monitored, both <I>in vivo</I> and <I>ex vivo</I>, thus illustrating the potential of <B>Gal-Dox</B> as a colorectal cancer theranostic with great specificity.</P> <P>[DISPLAY OMISSION]</P>