01467nas a2200157   4500008004100000022001400041245017800055210006900233260000900302300001400311490000700325520080900332100002101141700001901162856012801181       2020                        eng d  a0743-746300aStudy of the phase-evolution mechanism of an Fe-Se system at the nanoscale: optimization of synthesis conditions for the isolation of pure phases and their controlled growth0 aStudy of the phaseevolution mechanism of an FeSe system at the n  cMAR   a2012-20220 v363 a<p>The iron selenide (Fe-Se) family of nanoparticles (FexSey-where x/y ranges from 1:2 to 1:1) has been fabricated by a thermal decomposition method. The control over solution chemistry has been developed by intensively investigating the effect of reaction parameters by means of wide-angle X-ray scattering, leading to the rich insights into the phase-evolution mechanism of the Fe-Se system. The phase transformation followed the FeSe2 -&gt; Fe3Se4 -&gt; Fe7Se8 -&gt; FeSe sequence in the temperature range of 110-300 degrees C. The deep mechanistic insight helped in the identification of optimized conditions needed to crystallize the individual phase of the Fe-Se system as well as control of the morphology, crystalline phase purity, and thermal stability of the obtained Fe-Se nanoparticles.</p>
1 aGhalawat, Monika1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/study-phase-evolution-mechanism-fe-se-system-nanoscale-optimization-synthesis-conditions01427nas a2200229   4500008004100000022001400041245012300055210006900178260000900247300001600256490000600272520062400278653001300902653001800915653002700933653001900960653002300979100002001002700002101022700002401043856013001067       2021                        eng d  a2365-654900aReplacement of loop residues in TBA by an abasic ethylene glycol spacer: effect on stability, structure and function**0 aReplacement of loop residues in TBA by an abasic ethylene glycol  cOCT   a10648-106500 v63 aThis article describes the synthesis of ethyleneglycol (E) phosphoramidite and its incorporation into the thrombin binding aptamer (TBA) sequence at loop positions. Circular dichroism (CD) study revealed no major disturbances in the secondary structure of TBA by the abasic E unit and the derived oligomers exhibited a typical antiparallel chair-like conformation similar to that of TBA. UV and CD spectroscopy, together with anti-coagulation and HPLC studies revealed that although nuclease stability was enhanced, and anti-coagulation reasonably good, the thermal stability of the quadruplexes was adversely affected.10aaptamers10aclotting time10aethylene glycol spacer10aG-quadruplexes10anuclease stability1 aWagh, Atish, A.1 aGhalawat, Monika1 aFernandes, Moneesha  uhttps://library.ncl.res.in/content/replacement-loop-residues-tba-abasic-ethylene-glycol-spacer-effect-stability-structure-and02365nas a2200157   4500008004100000022001400041245013200055210006900187260000800256300001400264490000800278520175000286100002102036700001902057856013102076       2021                        eng d  a1932-744700aStudy of growth kinetics of Fe3Se4 nanocrystallites and the influence of size and shape tunability on their magnetic properties0 aStudy of growth kinetics of Fe3Se4 nanocrystallites and the infl  cAPR  a7932-79430 v1253 a<p>Crystalline iron selenide (Fe3Se4) nanoparticles (NPs) present a useful model system for a fundamental understanding of magnetism apart from having potential applications in permanent-magnet-related technologies. Despite significant advancements in understanding of the nucleation and growth processes, control over size and shape tunability is nontrivial, especially for the transition metal chalcogenides (TMC). The Wulff theorem states that if a crystal can grow purely under thermodynamic control of parameters then it will adopt the shape determined by the surface-energy minimization, i.e., the surface energy minimization will drive the growth of each crystalline facet. However, the known or unknown, controllable or uncontrollable parameters of a typical reaction which makes kinetic growth more art than science, depending upon whether we understand them or not. There is hardly any study based on existing models and theories to explain the TMC morphology evolution. In this work, there is a conscious effort to know, understand, and control the individual role of various reaction pathways on the shape and size of the Fe3Se4 nanocrystals. A qualitative growth mechanism is proposed based on the diffusion and reaction processes. Furthermore, the influence of shape/size on the magnetic parameters such as coercivity (H-C), magnetization (M-60kOe), effective magnetic anisotropy constant (K-eff), energy product (BHmax), and average blocking temperature (T-B) is investigated for Fe3Se4 NPs. After diving deeper into the science of crystal growth, our insight provides valuable guidance on experimental conditions for the synthesis of Fe3Se4 NPs with tunable sizes/shapes which for the first time can be extended to most TMCs.</p>1 aGhalawat, Monika1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/study-growth-kinetics-fe3se4-nanocrystallites-and-influence-size-and-shape-tunability-their01683nas a2200157   4500008004100000022001400041245012500055210006900180260000800249300001400257490000800271520107600279100002101355700001901376856013001395       2022                        eng d  a1932-744700aRemarkable effect of Fe and Se composition on magnetic properties-comparative study of the Fe-Se system at the nanoscale0 aRemarkable effect of Fe and Se composition on magnetic propertie  cMAR  a4655-46630 v1263 a<p>
	Herein, for the first time, the correlation between the phase structure and the magnetic properties of the Fe-Se system has been presented for FexSey compounds-where x/y ranges from 1:2 to 1:1. These phases-orthorhombic (FeSe2), monoclinic (Fe3Se4), hexagonal (Fe7Se8), and tetragonal (beta-FeSe)-were synthesized using a one-pot thermal decomposition route at the nanoscale. The magnetic properties vary enormously with change in the Fe/Se ratio due to the change in the Fe2+/Fe3+ ratio, crystal field environment around the Fe ions, magnetocrystalline anisotropy, Fe vacancies, and so forth. Among the four Fe-Se phases studied, two of them, Fe3Se4 and Fe7Se8, are ferrimagnetic below similar to 300 K and show semihard magnetic properties. The other two phases FeSe2 and beta-FeSe exhibiting weaker magnetism are less known for their magnetic properties. All these phases are prone to surface oxidation despite surface passivation, and its effect on the magnetic moment will be pronounced for the phases with weak magnetization such as FeSe2 and beta-FeSe.</p>
1 aGhalawat, Monika1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/remarkable-effect-fe-and-se-composition-magnetic-properties-comparative-study-fe-se-system02691nas a2200241   4500008004100000022001400041245009200055210006900147260000900216300001400225490000700239520188500246653002402131653002002155653001802175653001802193100002102211700002102232700001902253700002602272700002402298856012702322       2023                        eng d  a1530-437X00aSelf-powered wearable breath sensor cum nanogenerator using AuNR-rGO-PVDF nanocomposite0 aSelfpowered wearable breath sensor cum nanogenerator using AuNRr  cAPR   a6473-64800 v233 a<p>
	Breathing is the most important function of living being. It is well known that breath contains 90% humidity along with various gases and volatile organic compounds (VOCs). These gases are released during various metabolic activities in the body. These gases present in the breath can act as biomarkers to showcase healthiness or abnormalities in the body. Therefore, breath sensors are the need of time to detect diseases at early stages and in noninvasive way. Herein, we report, simple breath sensor using Au nanorods (AuNRs) and its nanocomposite with reduced graphene oxide (rGO) and polyvinylidene fluoride (PVDF). The nanocomposites system is designed in such a way that each component has its advantages for breath sensing. Here, AuNR being a good humidity sensitive material detects the breath efficiently. The ss phased PVDF being a very good ferroelectric material, contributes for voltage generation during sensing and enables the device to be self powered. The highly conducting rGO increases the sensitivity and voltage generation by facilitating the electron transport in the nanocomposite system. The nanocomposite was optimized with respect to PVDF, rGO and Au concentration. The as-synthesized materials were characterized by physiochemical characterization techniques such as field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The ss phase formation of the PVDF was confirmed from the XRD peak at 20.41 degrees. SEM results revealed that AuNR have length 15-20 nm and aspect ratio similar to 3-4. Breath sensing tests were carried out for as synthesized nanocomposite material. The nanocomposite exhibited high sensitivity towards breath and generated the voltage of similar to 0.7 V within 0.8 s.</p>
10aAu nanorods (AuNRs)10abreath analyzer10abreath sensor10ananogenerator1 aBang, Amruta, D.1 aGhalawat, Monika1 aPoddar, Pankaj1 aKulkarni, Sulabha, K.1 aAdhyapak, Parag, V.  uhttps://library.ncl.res.in/content/self-powered-wearable-breath-sensor-cum-nanogenerator-using-aunr-rgo-pvdf-nanocomposite02060nas a2200193   4500008004100000022001400041245013600055210006900191260000800260490000700268520132600275653002501601653002401626653003301650100001801683700002101701700001901722856012501741       2025                        eng d  a1434-194800aAn in-depth study of the Fe-Se system at the nanoscale reveals remarkable results on the electrocatalytic oxygen evolution reaction0 aindepth study of the FeSe system at the nanoscale reveals remark  cMAR0 v283 a<p>
	A catalyst for an electrocatalytic oxygen evolution reaction (OER) is a key component of the large-scale storage of renewable energy through the conversion of water into oxygen and hydrogen. Iron-based selenide materials are currently being considered as potential options for electrocatalytic oxygen evolution reaction (OER) because of their, widespread availability, low cost, and outstanding performance. In this study, we employed a thermal decomposition method to synthesize all stable phases of the Fe-Se system, including Fe7Se8, Fe3Se4, FeSe2, and FeSe. Additionally, we slurry-coated these phases onto a three-dimensional (3D) nickel foam substrate. The prepared 3D electrodes of Fe7Se8, Fe3Se4, FeSe2, and FeSe exhibit remarkably low overpotentials of 270, 276, 299, and 289 mV at a current density of 50 mA/cm2 for OER. In addition, the catalytic activity for OER is also tested on glassy carbon electrodes to compare its performance with the Ni-foam 3D substrate. The Fe7Se8 phase in the Fe-Se system exhibits the highest catalytic activity towards OER on both substrates due to variations in the Fe2+/Fe3+ ratio and the presence of Fe vacancies (cation vacancies) within the crystal lattice. Moreover, a faradaic efficiency of 98 % was exhibited by Fe7Se8 for the oxygen evolution reaction (OER).</p>
10aIron selenide system10aOER electrocatalyst10aThermal decomposition method1 aSingh, Dinesh1 aGhalawat, Monika1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/depth-study-fe-se-system-nanoscale-reveals-remarkable-results-electrocatalytic-oxygen