Magnetic ground state of the multiferroic hexagonal LuFeO3

Suresh, Pittala,Vijaya Laxmi, K.,Bera, A. K.,Yusuf, S. M.,Chittari, Bheema Lingam,Jung, Jeil,Anil Kumar, P. S. American Physical Society 2018 Physical Review B Vol.97 No.18

<P>The structural, electric, and magnetic properties of bulk hexagonal LuFeO3 are investigated. Single phase hexagonal LuFeO3 has been successfully stabilized in the bulk form without any doping by sol-gel method. The hexagonal crystal structure with P6(3)cm space group has been confirmed by x-ray-diffraction, neutron-diffraction, and Raman spectroscopy study at room temperature. Neutron diffraction confirms the hexagonal phase of LuFeO3 persists down to 6 K. Further, the x-ray photoelectron spectroscopy established the 3+ oxidation state of Fe ions. The temperature-dependent magnetic dc susceptibility, specific heat, and neutron-diffraction studies confirm an antiferromagnetic ordering below the Neel temperature (T-N) similar to 130 K. Analysis of magnetic neutron-diffraction patterns reveals an in-plane (ab-plane) 120 degrees antiferromagnetic structure, characterized by a propagation vector k = (0 0 0) with an ordered moment of 2.84 mu(B)/Fe3+ at 6 K. The 120 degrees antifferomagnetic ordering is further confirmed by spin-orbit coupling density functional theory calculations. The on-site coulomb interaction (U) and Hund's parameter (J(H)) on Fe atoms reproduced the neutron-diffraction Gamma(1) spin pattern among the Fe atoms. P-E loop measurements at room temperature confirm an intrinsic ferroelectricity of the sample with remnant polarization P-r similar to 0.18 mu(C) cm(2). A clear anomaly in the dielectric data is observed at similar to T-N revealing the presence of magnetoelectric coupling. A change in the lattice constants at T-N has also been found, indicating the presence of a strong magnetoelastic coupling. Thus a coupling between lattice, electric, and magnetic degrees of freedom is established in bulk hexagonal LuFeO3.</P>

Cytotoxicity, Apoptosis Induction and Anti-Metastatic Potential of Oroxylum indicum in Human Breast Cancer Cells

Kumar, D.R. Naveen,George, V. Cijo,Suresh, P.K.,Kumar, R. Ashok Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Despite clinical advances in anticancer therapy, there is still a need for novel anticancer metabolites, with higher efficacy and lesser side effects. Oroxylum indicum (L.) Vent. is a small tree of the Bignoniaceae family which is well known for its food and medicinal properties. In present study, the chemopreventive properties of O. indicum hot and cold non-polar extracts (petroleum ether and chloroform) were investigated with MDA-MB-231 (cancer cells) and WRL-68 (non-tumor cells) by XTT assay. All the extracts, and particularly the petroleum ether hot extract (PHO), exhibited significantly (P<0.05) higher cytotoxicity in MDA-MB-231 when compared to WRL-68 cells. PHO was then tested for apoptosis induction in estrogen receptor (ER)-negative (MDA-MB-231) and ER-positive (MCF-7) breast cancer cells by cellular DNA fragmentation ELISA, where it proved more efficient in the MDA-MB-231 cells. Further, when PHO was tested for anti-metastatic potential in a cell migration inhibition assay, it exhibited beneficial effects. Thus non-polar extracts of O. indicum (especially PHO) can effectively target ER-negative breast cancer cells to induce apoptosis, without harming normal cells by cancer-specific cytotoxicity. Hence, it could be considered as an extract with candidate precursors to possibly harness or alleviate ER-negative breast cancer progression even in advanced stages of malignancy.

Eight Year Survival Analysis of Patients with Triple Negative Breast Cancer in India

Doval, Dinesh Chandra,Suresh, P,Sinha, Rupal,Azam, Saud,Batra, Ullas,Talwar, Vineet,Kumar, Kapil,Mehta, Anurag Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.6

Background: Triple-negative breast cancer (TNBC) often presents as an interval cancer with short survival upon metastasis and thus represents an important clinical challenge. The present study investigated the clinicopathologic characteristics and long term survival outcome of early and locally advanced TNBC. Materials and Methods: Medical records were reviewed retrospectively for 148 consecutive confirmed cases of TNBC treated in a single unit at our centre. Demographic profile, tumor type, histopathology details, treatment and follow-up information was recorded and immunohistochemistry was performed. Results: Age group >50 years was associated with tumors of clinical stage 3 (53.8%), pathological stage 3 (46.2%), pathological grade 3 (45.7%), presence of extracapsular extension (ECE, 48.5%) and lymphovascular invasion (LVI, 64.9%). Locally advanced breast cancers (LABCs) were characterized by pathological stage 3 (96.2%), presence of ECE (100%) and absence of LVI (46.7%) as compared to early breast cancers (EBCs) which had higher incidence of lower stage tumors (100%), absence of ECE (82%) and presence of LVI (91.9%; p-value <0.001. Better relapse free survival was observed in patients with no axillary involvement (69%; p-value <0.001) and absence of ECE (64%; p-value <0.001). Improved overall survival was seen in patients with EBC (90%; p-value 0.008), clear axilla (86%; p-value <0.001), absence of ECE (87%; p-value <0.001) and negative lymph nodes (90%; p-value 0.006). Conclusions: TNBCs are aggressive tumors which show poor long term survival. Patients with TNBC benefit from chemotherapy, thus better and less toxic treatment options are needed. Identification of newer targets and development of targeted therapies are the need of the hour.

Quantitative Assessment of the Relative Antineoplastic Potential of the n-butanolic Leaf Extract of Annona Muricata Linn. in Normal and immortalized Human Cell Lines

George, V. Cijo,Kumar, D.R. Naveen,Rajkumar, V.,Suresh, P.K.,Kumar, R. Ashok Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.2

Natural products have been the target for cancer therapy for several years but there is still a dearth of information on potent compounds that may protect normal cells and selectively destroy cancerous cells. The present study was aimed to evaluate the cytotoxic potential of n-butanolic leaf extract of $Annona$ $muricata$ L. on WRL-68 (normal human hepatic cells), MDA-MB-435S (human breast carcinoma cells) and HaCaT (human immortalized keratinocyte cells) lines by XTT assay. Prior to cytotoxicity testing, the extract was subjected to phytochemical screening for detecting the presence of compounds with therapeutic potential. Their relative antioxidant properties were evaluated using the reducing power and $DPPH^*$radical scavenging assay. Since most of the observed chemo-preventive potential invariably correlated with the amount of total phenolics present in the extract, their levels were quantified and identified by HPLC analysis. Correlation studies indicated a strong and significant (P<0.05) positive correlation of phenolic compounds with free radical scavenging potential. The results revealed that the extract was moderately cytotoxic to normal cells with a mean IC50 value of 52.4 ${\mu}g$ when compared with those obtained for cancerous cells (IC50 values of 29.2 ${\mu}g$ for MDA-MB-435S and 30.1 ${\mu}g$ for HaCaT respectively). The study confirms the presence of therapeutically active antineoplastic compounds in the n-butanolic leaf extract of $Annona$ $muricata$. Isolation of the active metabolites from the extract is in prospect.

Deposition rate dependent phase/mechanical property evolution in zirconia and ceria-zirconia thin film by EB-PVD technique

Arunkumar, P.,Aarthi, U.,Sribalaji, M.,Mukherjee, B.,Keshri, Anup Kumar,Tanveer, Waqas Hassan,Cha, Suk-Won,Babu, K. Suresh Elsevier 2018 Journal of alloys and compounds Vol.765 No.-

<P><B>Abstract</B></P> <P>Pure zirconia (ZrO<SUB>2</SUB>) and ceria (16 mol%) stabilized zirconia (CeSZr) thin films were prepared by electron beam physical vapor deposition with varying deposition rates (1, 4 and 8 Å/s) in order to correlate the phase changes to the mechanical property. X-ray diffraction and Raman spectra results indicate the presence of mixed monoclinic and tetragonal phases in ZrO<SUB>2</SUB> film, but tetragonal phase dominated at lower deposition rate. However, irrespective of the deposition rate, cerium addition to ZrO<SUB>2</SUB> resulted in complete stabilization of tetragonal phase. Depending on the presence of dual (ZrO<SUB>2</SUB>) or single (CeSZr) phase, either surface cracks or well-connected grain structure was observed in SEM, respectively. Thus, CeSZr film showed a four-fold increase in hardness in comparison to ZrO<SUB>2</SUB>, which can be attributed to the complete stabilization of tetragonal phase that hinders the crack propagation along the grain. Plastic deformation of CeSZr film was found to be 1.80 × 10<SUP>−2</SUP> GPa, which is about ∼55% higher as compared to pure ZrO<SUB>2</SUB> film (8.04 × 10<SUP>−3</SUP> GPa). Thus, the development of CeSZr coating may lead to better surface protection of many components.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zirconia and ceria (16 mol%) stabilized zirconia (CeSZr) films deposited by EB-PVD. </LI> <LI> ZrO2 thin film showed mixed tetragonal and cubic structure. </LI> <LI> CeSZr thin film formed with single phase tetragonal structure. </LI> <LI> CeSZr film exhibited a four-fold increase in hardness in comparison to ZrO2 film. </LI> <LI> Deposition rate and chemistry influence the mechanical property of films. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Heat transfer enhancement and pressure drop analysis in a helically coiled tube using Al₂O₃ / water nanofluid

P. C. Mukesh Kumar,J. Kumar,R. Tamilarasan,S. Sendhil Nathan,S. Suresh 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.5

In this experimental investigation, the heat transfer and pressure drop analysis of a shell and helically coiled tube heat exchanger by using Al₂O₃ / water nanofluids have been carried out under turbulent flow condition. The Al₂O₃/ water nanofluids of 0.1%, 0.4%, and 0.8%particle volume concentration have been prepared by using two step method. The tube side experimental Nusselt number of 0.1%, 0.4%and 0.8% nanofluids were found to be 28%, 36% and 56%, respectively higher than water. These enhancements are due to higher thermalconductivity of nanofluid, better fluid mixing and strong secondary flow formation in coiled tube. The pressure drop of 0.1%, 0.4%and 0.8% were found to be 4%, 6%, and 9%, respectively higher than water. The increase in pressure drop is due to increase in nanofluidviscosity while adding nanoparticles. The measurement of nanofluid thermal performance factor is found to be greater than unity. It isconcluded that the Al₂O₃ nanofluid can be applied as a coolant in helically coiled tube heat exchanger to enhance heat transfer with negligiblepressure drop.

Drastic photocatalytic degradation of methylene blue dye by neodymium doped zirconium oxide as photocatalyst under visible light irradiation

Dhandapani, C.,Narayanasamy, R.,Karthick, S.N.,Hemalatha, K.V.,Selvam, S.,Hemalatha, P.,kumar, M. Suresh,Kirupha, S. Dinesh,Kim, Hee-Je Elsevier 2016 OPTIK -STUTTGART- Vol.127 No.22

<P><B>Abstract</B></P> <P>Nanocrystalline ZrO<SUB>2</SUB> and neodymium doped ZrO<SUB>2</SUB> (Nd–ZrO<SUB>2</SUB>) were successfully prepared by a polymer- assisted, sol-gel method and characterized by XRD, SEM, HRTEM, XPS and UV–vis techniques. X-Ray diffraction studies revealed the formation of highly crystalline structures of ZrO<SUB>2</SUB> and (Nd–ZrO<SUB>2</SUB>) samples. SEM images proved the evenly distributed nano - structured, spherically - shaped ZrO<SUB>2</SUB> particles of size 40nm, which was reduced to 20nm, when doped with neodymium. Light absorption properties of the nanoparticles were studied by UV–vis spectrophotometer. Nd - doped ZrO<SUB>2</SUB> was having a band gap of 2.8ev, while that of ZrO<SUB>2</SUB>, was 2.6ev. Thus, Nd substituted ZrO<SUB>2</SUB> effected substantial shifting of the absorption edge of zirconium oxide to red and resulting in the enhancement of visible light absorption The increase in band gap of Nd–ZrO<SUB>2</SUB> was resulted in an increasing light absorbtion tendency of Nd−ZrO<SUB>2</SUB>, which promoted the photocatalytic efficiency of it. XPS results confirmed substitution of Nd in ZrO<SUB>2</SUB>. Photocatalytic results for the degradation of methylene blue had indicated the fact that neodymium substitution dramatically enhanced the catalytic activity of zirconium oxide. This means that the neodymium − substituted zirconium oxide has the highest photocatalytic activity under visible light irradiation.</P>

Surface and Internal Waves Scattering by Partial Barriers in a Two-Layer Fluid

Kumar, P.Suresh(슈레쉬 쿠마),Oh, Young-Min(오영민),Cho, Won-Chul(조원철) 한국해안해양공학회 2008 한국해안해양공학회 논문집 Vol.20 No.1

파랑은 주로 바람에 의해서 발생하여 많은 에너지를 해안으로 전달하며 각종 수리현상을 야기하고 물질의 이송 등에 의하여 연안환경 뿐만 아니라 인간의 활동에도 큰 영향을 미친다. 또한, 해안 구조물과 파랑의 상호작용에 의한 효과를 정확히 예측하는 것은 구조물의 설계 및 거동특성 파악에 매우 중요하다. 본 논문에서는 이층 유체에서 수표면과 저층에 설치되어 있는 얇은 연직벽에 의한 표면파와 내부파의 분산을 선형파 이론을 이용하여 이차원으로 해석하였다. 반사계수를 계산하여 여러 경우에 대하여 효과를 분석한 결과 반사계수는 구조물의 형상과는 별도로 경계층의 위치와 유체간의 밀도차에 크게 영향을 받는 것으로 밝혀졌다. Water waves are generated mainly by winds in open seas and large lakes. They carry a significant amount of energy from winds into near-shore region. Thereby they significantly contribute to the regional hydrodynamics and transport process, producing strong physical, geological and environmental impact on coastal environment and on human activities in the coastal area. Furthermore an accurate prediction of the hydrodynamic effects due to wave interaction with offshore structures is a necessary requirement in the design, protection and operation of such structures. In the present paper surface and internal waves scattering by thin surface-piercing and bottom-standing vertical barriers in a two-layer fluid is analyzed in two-dimensions within the context of linearized theory of water waves. The reflection coefficients for surface and internal waves are computed and analyzed in various cases. It is found that wave reflection is strongly dependent on the interface location and the fluid density ratio apart from the barrier geometry.

Electrodeposition of WO₃ nanostructured thin films for electrochromic and H₂S gas sensor applications

Poongodi, S.,Kumar, Palaniswamy Suresh,Mangalaraj, D.,Ponpandian, N.,Meena, P.,Masuda, Yoshitake,Lee, Chongmu Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.719 No.-

<P><B>Abstract</B></P> <P>In this work, Vertically oriented WO<SUB>3</SUB> nanoflakes array films was synthesized via the template free facile electrodeposition method at room temperature. WO<SUB>3</SUB> nanoflakes arrays was adopted as an effective cathode electrode material in the electrochemical devices structure. The WO<SUB>3</SUB> material exhibits superior electrochromic performance shows a larger optical modulation (68.89% at 550 nm), faster response time (t<SUB>b</SUB> = 1.93 s, t<SUB>c</SUB> = 2.87 s), a higher coloration efficiency of about 154.93 cm<SUP>2</SUP> C<SUP>−1</SUP> and with excellent cyclic stability over 2000 cycles without any degradation. Futhermore, WO<SUB>3</SUB> nanoflakes array film was used for the detection of H<SUB>2</SUB>S gas that showed excellent response. A considerable increase in porosity and high surface roughness could be conducive for such an excellent and superior electrochromic characteristic as well as gas sensing performances. These results indicates that fabricated WO<SUB>3</SUB> nanoflakes array film by a simple strategy holds a great promise for potential multifunctional applications such as smart windows, gas sensors and optical sensors.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Experimental investigation on convective heat transfer and friction factor in a helically coiled tube with Al₂O₃ / water nanofluid

P. C. Mukesh Kumar,J. Kumar,S. Suresh 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.1

In this study, the heat transfer and friction factor of a shell and helically coiled tube heat exchanger using Al2O3 / water nanofluid at 0.1%, 0.4% and 0.8% particle volume concentration were tested. The test was conducted under laminar flow condition at 5100 < Rei < 8700. It is found that the overall heat transfer coefficient, inner heat transfer coefficient and experimental inner Nusselt number are 24%, 25% and 28%, respectively, higher than water at 0.8% particle volume concentration of nanofluid. It is observed that the presence of nanoparticles further intensify the formation of secondary flow and proper mixing of fluid when nanofluid passes through the helically coiled tube. Apart from further flow intensification, higher thermal conductivity of nanofluid and random movement of nanoparticles contribute to the enhanced heat transfer coefficient. Also found that the friction factor increases over particle volume concentration and this is due to increased nanofluid viscosity while increasing particle volume concentration.