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Karunakaran, Gopalu,Suriyaprabha, Rangaraj,Rajendran, Venkatachalam,Kannan, Narayanasamy Techno-Press 2015 Advances in nano research Vol.3 No.4
In this investigation, ecotoxicity of nano and micro metal oxides, namely silica ($SiO_2$) and alumina ($Al_2O_3$), on the growth of green algae (Porphyridium aerugineum Geitler) is discussed. Effects of nano and micro particles on the growth, chlorophyll content and protein content of algae are analysed using standard protocols. Results indicate that $SiO_2$ nano and micro $SiO_2$ particles are non-toxic to P. aerugineum Geitler up to a concentration of 1000 mg/L. In addition, $Al_2O_3$ microparticles are less toxic to P. aerugineum Geitler, whereas $Al_2O_3$ nanoparticles are found to be highly toxic at 1000 mg/L. Moreover, $Al_2O_3$ nanoparticles decrease the growth, chlorophyll content, and protein content of tested algae. In addition, zeta potential and contact angle are also important in enhancing the toxicity of metal oxide nanoparticles in aquatic environment. This study highlights a new insight into toxicity evaluation of nanoparticles on beneficial aquatic organisms such as algae.
Antibacterial mesoporous Sr-doped hydroxyapatite nanorods synthesis for biomedical applications
Gopalu Karunakaran,Eun-Bum Cho,Keerthanaa Thirumurugan,Govindan Suresh Kumar,Evgeny Kolesnikov,Selvakumar Boobalan Techno-Press 2023 Advances in nano research Vol.14 No.6
Postsurgical infections are caused by implant-related pathogenic microorganisms that lead to graft rejection. Hence, an intrinsically antibacterial material is required to produce a biocompatible biomaterial with osteogenic properties that could address this major issue. Hence, this current research aims to make strontium-doped hydroxyapatite nanorods (SrHANRs) via an ethylene diamine tetraacetic acid (EDTA)-enable microwave mediated method using Anodontia alba seashells for biomedical applications. This investigation also perceives that EDTA acts as a soft template to accomplish Sr-doping and mesoporous structures in pure hydroxyapatite nanorods (HANRs). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis reveals the crystalline and mesoporous structures, and Brunauer-Emmett-Teller (BET) indicates the surface area of all the samples, including pure HANRs and doped HANRs. In addition, the biocidal ability was tested using various implant-related infectious bacteria pathogens, and it was discovered that Sr-doped HANRs have excellent biocidal properties. Furthermore, toxicity evaluation using zebrafish reports the non-toxic nature of the produced HANRs. Incorporating Sr<sup>2+</sup> ions into the HAp lattice would enhance biocompatibility, biocidal activity, and osteoconductive properties. As a result, the biocompatible HANRs materials synthesized with Sr-dopants may be effective in bone regeneration and antibacterial in-built implant applications.
Manab Kundu,Gopalu Karunakaran,Evgeny Kolesnikov,Voynova Elena Sergeevna,Shilpa Kumari,Mikhail V. Gorshenkov,Denis Kuznetsov 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-
The hollow NiCo2O4 nano-spheres (∼300–500 nm) are synthesized by ultrasonic spray pyrolysis method and used as electrode for high-performance supercapacitor (SC) and lithium-ion battery (LIB). When used in SC application, the hollow NiCo2O4 deliver a specific capacitance of ∼1000 F g−1 even after 3000 charge–discharge cycles. In addition, as an anode material for LIBs, it exhibits admirable high capacity values of 763 and 516 mA h g−1 after 1000 cycles at a current density of 1500 and 3000 mAh g−1, respectively. The excellent electrochemical performance of this hollow NiCo2O4 nano-sphere indicates its potential applications for next generation SCs and LIBs.
Nguyen Van Minh,Yury Konyukhov,Gopalu Karunakaran,Dmitry Ryzhonkov,Tang Duong,Sergey Kotov,Denis Kuznetsov 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.3
In the present study, the influence of nano additives (Ni, Fe) and different mixing (turbular and magnetic) on thedensification, microstructure and micro-hardness of the tungsten material under spark plasma sintering is analyzed. After turbulent mixing the nanoparticles are distributed widely in the W interparticle gaps but after magneticmixing the nanoparticles are distributed not only on the gaps of the W particles but also on the broken surfaces. Niincorporated tungsten materials achieved the maximum density of 98.3% at 1400 °C (turbular mixing) and 97.9%at 1300 °C (magnetic mixing). Fe incorporated tungsten material showed density of 97.7% at 1600 °C and 97.2%at 1400 °C after turbular and magnetic mixing. The influence of nanoparticles in the densification process wasexplained by Laplace force, boundary slip and Agte-Vacek effect. The microstructural analysis showed that nanomodificationreduced the degree of porosity, and provides a compact material at low temperatures. X-ray fluorescenceanalysis reveals that magnetic mixing shows more uniform distribution of nanoparticles than turbular mixing. Thenanoparticles incorporation increased the micro hardness of tungsten material. Hence, it is clear that magnetic mixingand nano modification greatly improved the densification and sintering behavior of the tungsten material.
Facile and novel synthetic method to prepare nano molybdenum and its catalytic activity
Jaikumar, Sugumaran Sam,Yuvakkumar, Rathinam,Suriya Prabha, Rangaraj,Karunakaran, Gopalu,Rajendran, Venkatachalam,Sun Ig Hong IET 2015 IET nanobiotechnology Vol.9 No.4
<P>This study reports on a facile and economical synthetic method to prepare nano molybdenum by solid-state reaction technique. Metallic nano molybdenum was synthesised from molybdenum trioxide, molybdenum IV oxide and molybdenum VI oxide through thermal decomposition technique. Metallic nano molybdenum prepared from molybdenum IV oxide was used to study the catalytic effect of molybdenum nanoparticles on the growth of <I>Anabaena</I> sp. The increase in concentration of nano molybdenum from 0.1 to 100% in BG11 (N<SUP>-</SUP>Mo<SUP>-</SUP> + nano Mo) medium increases heterocyst frequency. The chlorophyll and protein content in <I>Anabaena</I> sp. was found to improve when compared with bulk molybdenum particles and showed a positive influence to be used as a nano nutrient for <I>Anabaena</I> sp.</P>
Fabrication of AA2024/SiCp Metal Matrix Composite by Mechanical Alloying
O. V. Rofman,A. S. Prosviryakov,A. D. Kotov,A. I. Bazlov,P. O. Milovich,Gopalu Karunakaran,A. V. Mikhaylovskaya 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3
Mechanical alloying is a widely used alternative to the liquid-phase method of embedding reinforcements to manufacturemetal matrix composites (MMC). In this research, high-energy ball milling was used to distribute various volume fractionsof sub-micron-sized SiCpparticles (2, 10, and 20 vol%) in AA2024 aluminum powder alloy, focusing on powder morphologyand milling conditions. An increase in the full width at half-maximum and the shifting of peaks at higher angles wereobserved after mechanical alloying. These examinations were attributed to changes in the lattice parameters of the matrixalloy. It was noted that the temperature and loading pressure during the die compaction stages of MMC powders directlyaffect the compact density, whereas the volume fraction of SiCpchanges hardness. Compression testing, conducted at elevatedtemperatures to evaluate the plastic properties of the material, showed sufficient ductility characteristics for thermomechanicalprocessing.