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Singh Vinaya Kumar,Kumar Sanjay,Awasthi Sadhna,Gupta Sandeep Kumar 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.4
Understanding population genetics, genetic diversity and the migration pattern of ecologically important species is crucial for effective conservation plans. We studied mitochondrial cytochrome c oxidase subunit-I (COI) gene variation in painted lady butterfly (Vanessa cardui) from different altitudinal gradients of Uttarakhand (Western Himalayas), India. We sequenced COI) gene of 91 samples and 22 COI sequences retrieved from GenBank as representatives of different localities for comparative analysis. We observed a total of 16 haplotypes, of which seven haplotypes were observed in Uttarakhand with intra-species sequence divergence ranges from 0.001 to 0.009. Haplotype (Hd) and nucleotide diversity (π) were comparatively low and averaging 0.635 and 0.002, respectively. The neutrality test, mismatch distribution graph and observed pattern of diversity indices (Hd and π) revealed population expansion. It was further confirmed by the Median Joining Network, which exhibited a star-like topology from the core haplotype, while the Bayesian phylogenetic tree displayed a mixing of haplo types from different localities to an identical clade. Haplotype organization in the Bayesian tree and Median Joining Network was not clustered as per their topographical affinity, indicating incomplete lineage sorting and late species population development or colonization in the novel area.
Singh Vinaya Kumar,Joshi Prakash Chandra,Gupta Sandeep Kumar 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.2
DNA barcodes in species tagging have become a popular tool for taking inventories of species from different groups worldwide. The present study aimed to generate DNA barcodes of butterfly species from the Western Himalayas in Uttarakhand, India. The Indian Western Himalayan region (IWHR) has been explored to a limited extent about butterfly species’ diversity. However, the IWHR is prone to environmental change, and slight variations in climatic conditions can influence species diversity and change butterflies’ range. The mitochondrial cytochrome c oxidase I (COI) gene was first used to generate the DNA barcode for butterflies from this region on a broad scale. 28 morphologically identified species, consisting of 102 sequences, were finally grouped into 26 species, with only two species showing ambiguity in species identification. These species had < 3% sequence variations from their neighboring relatives, suggesting cryptic species diversity. Generated sequences were also compared with the GenBank data of conspecific geographical locations, which showed intraspecies variation ranging from 1.3% to 7.3%. It was also noted that butterfly species have both intra and interspecies sequence divergence. In the phylogenetic-based species identification, a total of 28 species belonging to 4 families of butterflies were successfully discriminated, and two species at the genus level, which had high intra-specific divergence (0.025), were considered. However, the high intra-species sequence divergence observed may represent the presence of hidden species.
Structural and Magnetic Properties of Gd-Ni-co-doped BiFeO₃ Nanoparticles
Sandeep Kumar Singh Patel,Jae-Hyeok Lee,Min-Kwan Kim,Sang-Koog Kim 한국자기학회 2019 Journal of Magnetics Vol.24 No.3
Single-phase (GdNi)x(BiFe)1-x O₃ (x = 0, 0.025, and 0.05) nanoparticles of 30-40 nm particle size on average were fabricated using a sol-gel method. Transmission electron microscopy, X-ray diffraction as well as Raman spectral measurements and analyses revealed that the (GdNi)x(BiFe)1-xO₃ nanoparticles undergo a structural transformation from the rhombohedral R3c structure (for x = 0 and 0.025) to the triclinic P1 (for x = 0.05). X-ray photoemission spectroscopy served to confirm that co-doping of Gd<SUP>3+</SUP> and Ni<SUP>2+</SUP> ions decreases oxygen-vacancy concentration, reflecting less Fe<SUP>2+</SUP> content in the co-doped samples compared with pure BiFeO₃. Magnetization hysteresis loops showed that the magnetization value for x = 0.05 at 50 kOe increases significantly to M = 5.32 emu/g at 300 K and to 14.47 emu/g at 5 K, representing 760 and 690 % enhancements relative to those for x = 0. Fitting of the Curie-Weiss law to the observed magnetization-versus-temperature curves indicated the presence of weak ferromagnetic coupling in the samples. We also noted the exchange bias effect in the nano-size particles, possibly originating from exchange coupling between surface spins of an uncompensated ferromagnetic nature and core spins of an antiferromagnetic nature. We ascribed these significant improvements in the Gd-Ni-co-doped BiFeO₃ nanoparticles’ magnetic properties to the rhombohedral R3c to triclinic P1 structural transformation, due to the samples’ particle size being smaller than the modulation length of the canted antiferromagnetic ordering of the Fe<SUP>3+</SUP> spins. These enhanced magnetic properties, notably, might prove useful for a variety of spintronic applications.
Patel, Sandeep Kumar Singh,Lee, Jae-Hyeok,Bhoi, Biswanath,Lim, Jung Tae,Kim, Chul Sung,Kim, Sang-Koog Elsevier 2018 Journal of magnetism and magnetic materials Vol.452 No.-
<P><B>Abstract</B></P> <P>We fabricated Gd-doped Y<SUB>3</SUB>Fe<SUB>5</SUB>O<SUB>12</SUB> (YIG) nanoparticles by a modified sol–gel method. We investigated the effects of isovalent Gd<SUP>3+</SUP>-ion substitution on the structural and magnetic properties of Y<SUB>3−x</SUB>Gd<SUB>x</SUB>Fe<SUB>5</SUB>O<SUB>12</SUB> (0 ≤ x ≤ 3) nanoparticles. Isovalent Gd<SUP>3+</SUP>-ion substitution for Y<SUP>3+</SUP> leads to lattice expansion and change in the Fe(<I>a</I>)–O–Fe(<I>d</I>) bond angle. The X-ray photoemission spectroscopy and Mössbauer measurements revealed a high-spin state of Fe<SUP>3+</SUP>. The Mössbauer analysis showed an increase in the Fe<SUB>(d)</SUB> <SUP>3+</SUP>/Fe<SUB>(a)</SUB> <SUP>3+</SUP> ratio, indicating a relocation of Y<SUP>3+</SUP> ions at the dodecahedral sites and Fe<SUP>3+</SUP> ions at the octahedral sites. The magnetic properties could be explained in terms of magnetic-structural evolution with increasing Gd<SUP>3+</SUP> content. The field dependence of magnetization indicated a clear decrease of the magnetization while the magnetic anisotropy first decreases and then increases with the increase of Gd<SUP>3+</SUP> content. These Gd<SUP>3+</SUP>-ion-substituted nanocrystalline garnet ferrites are suitable for use in a variety of magneto-optical applications.</P>
Patel, Sandeep Kumar Singh,Lee, Jae-Hyeok,Kim, Min-Kwan,Bhoi, Biswanath,Kim, Sang-Koog The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.3
<P>We fabricated single-crystalline, Gd-doped BiFeO3 (BFO) nanowires using a hydrothermal technique. X-ray diffraction (XRD) data combined with their Rietveld refinements and high-resolution transmission electron microscopy (HRTEM) revealed pure single-phase crystalline Bi1−xGdxFeO3 (<I>x</I> = 0, 0.05, 0.10) nanowires of 40-60 nm diameter and their structural transformation from the rhombohedral <I>R</I>3<I>c</I> (for <I>x</I> = 0 and 0.05) to the orthorhombic <I>Pn</I>21<I>a</I> crystal structure (for <I>x</I> = 0.10). The addition of Gd<SUP>3+</SUP> ions to the pure-phase BFO leads to remarkable changes in the structural and magnetic properties, and these effects are caused by differences in the ionic-radii and magnetic moment between the Bi<SUP>3+</SUP> and Gd<SUP>3+</SUP> ions. According to the observed magnetization-field (<I>M-H</I>) and magnetization-temperature (<I>M</I>-<I>T</I>) curves, with increasing Gd<SUP>3+</SUP> concentration, the saturation magnetization (<I>M</I>S), squareness (<I>M</I>r/<I>M</I>S), coercivity (<I>H</I>C), exchange-bias field (<I>H</I>EB) and magnetocrystalline anisotropy (<I>K</I>) increased markedly, by <I>M</I>S = 1.26 emu g<SUP>−1</SUP> (640%), <I>M</I>r/<I>M</I>S = 0.19 (20.5%), <I>H</I>C = 7788 Oe (4560%), <I>H</I>EB = 501 Oe (880%) and <I>K</I> = 1.62 × 10<SUP>5</SUP> erg cm<SUP>−3</SUP> (3500%), for <I>x</I> = 0.10 relative to the data for <I>x</I> = 0. In such Gd-doped BFO nanowire samples, spin-canted Dzyaloshinskii-Moriya interaction, remarkable enhancements in the magnetocrystalline anisotropy as well as uncompensated surface ferromagnetic spin states in the antiferromagnetic core regions were also found. Such remarkable enhancements in Gd-doped BFO nanowires might offer a variety of spintronic applications.</P>
Kumar Sandeep,Ngo Van Tho,Park Jeong,Ham Kyung‐Sik,Singh Vivek K.,Nam Sang‐Ho,Lee Yonghoon 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.5
Strontium (Sr) is an element of toxicological concern due to its close chemical proximity to Ca. In this work, Sr in sea salts collected from China and South Korea was analyzed by laser-induced breakdown spectroscopy (LIBS). The precision could be improved by using multiple filter-paper sampling and intensity normalization using a weak Na I line as a reference signal. The analyte signal variation between filter-paper pieces as well as that within a single filter-paper piece could be corrected by the suggested method. The limit of detection of ~2 ppm and the precision of ~5% could be obtained. As a measure of accuracy, the root-mean-square error was estimated to be 9 ppm. The multiple filter-paper sampling can be performed easily on the salt production sites and improves the LIBS analysis precision resulting to sufficient quantification capability for minor metallic elements in edible sea salt products.
Singh, Bhupendra,Bhardwaj, Aman,Gautam, Sandeep K.,Kumar, Devendra,Parkash, Om,Kim, In-Ho,Song, Sun-Ju Elsevier 2017 Journal of Power Sources Vol.345 No.-
<P><B>Abstract</B></P> <P>Here we present a report on synthesis and characterization of tetravalent metal pyrophosphate (TMP) and alkali carbonate (A<SUB>2</SUB>CO<SUB>3</SUB>; A = Li and/or Na) composites. The TMP-carbonate composites are prepared by mixing indium-doped tin pyrophosphate or yttrium-doped zirconium pyrophosphate with Li<SUB>2</SUB>CO<SUB>3</SUB> or an eutectic mixture of Li<SUB>2</SUB>CO<SUB>3</SUB>-Na<SUB>2</SUB>CO<SUB>3</SUB> in different wt.% ratios. The phase composition, microstructure and electrical conductivity of the sintered specimen are analyzed. In addition, the effect of different TMP and A<SUB>2</SUB>CO<SUB>3</SUB> phases is investigated. A maximum ionic conductivity of 5.5 × 10<SUP>−2</SUP> S cm<SUP>−1</SUP> at 630 °C is observed in this study with a Sn<SUB>0.9</SUB>In<SUB>0.1</SUB>P<SUB>2</SUB>O<SUB>7</SUB>-Li<SUB>2</SUB>CO<SUB>3</SUB> composite. Based on the literature data, TMP-carbonate composites can be considered to be primarily a proton and oxygen-ion co-ionic conductor and, therefore, have strong potential as electrolytes in fuel cells in 500–700 °C range.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New tetravalent metal pyrophosphate (TMP)-alkali carbonate composites are reported. </LI> <LI> TMP-carbonate composites sintered at 750 °C are dense. </LI> <LI> SIP21-L10 composite showed max. conductivity of 5.5 × 10<SUP>−2</SUP> S cm<SUP>−1</SUP> at 630 °C. </LI> <LI> Conductivity of TMP-carbonate is comparable to ceria-carbonate composites. </LI> </UL> </P>