Observation of gapless nodal-line states in NdSbTe

Lanthanide (Ln) based systems in the ZrSiS-type nodal-line semimetals have been subjects of research investigations as grounds for studying the interplay of topology with possible magnetic ordering and electronic correlations that may originate from the presence of Ln 4f electrons. In this study, we carried out a thorough study of a LnSbTe system - NdSbTe - by using angle-resolved photoemission spectroscopy along with first-principles calculations and thermodynamic measurements. We experimentally detect the presence of multiple gapless nodal-line states, which is well supported by first-principles calculations. A dispersive and an almost non-dispersive nodal-line exist along the bulk X-R direction. Another nodal-line is present well below the Fermi level across the G- M direction, which is formed by bands with high Fermi velocity that seem to be sensitive to light polarization. Our study provides an insight into the electronic structure of a new LnSbTe material system that will aid towards understanding the connection of Ln elements with topological electronic structure in these systems.Comment: 34 pages, 12 figures; Supplemental Material include

Observation of multiple van Hove singularities and correlated electronic states in a new topological ferromagnetic kagome metal NdTi3Bi4

Kagome materials have attracted enormous research interest recently owing to its diverse topological phases and manifestation of electronic correlation due to its inherent geometric frustration. Here, we report the electronic structure of a new distorted kagome metal NdTi3Bi4 using a combination of angle resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations. We discover the presence of two at bands which are found to originate from the kagome structure formed by Ti atoms with major contribution from Ti dxy and Ti dx2-y2 orbitals. We also observed multiple van Hove singularities (VHSs) in its electronic structure, with one VHS lying near the Fermi level EF. In addition, the presence of a surface Dirac cone at the G point and a linear Dirac-like state at the K point with its Dirac node lying very close to the EF indicates its topological nature. Our findings reveal NdTi3Bi4 as a potential material to understand the interplay of topology, magnetism, and electron correlation.Comment: 7 pages, 4 figure

Observation of multiple flat bands and topological Dirac states in a new titanium based slightly distorted kagome metal YbTi3Bi4

Kagome lattices have emerged as an ideal platform for exploring various exotic quantum phenomena such as correlated topological phases, frustrated lattice geometry, unconventional charge density wave orders, Chern quantum phases, superconductivity, etc. In particular, the vanadium based nonmagnetic kagome metals AV3Sb5 (A= K, Rb, and Cs) have seen a flurry of research interest due to the discovery of multiple competing orders. Here, we report the discovery of a new Ti based kagome metal YbTi3Bi4 and employ angle-resolved photoemission spectroscopy (ARPES), magnetotransport in combination with density functional theory calculations to investigate its electronic structure. We reveal spectroscopic evidence of multiple flat bands arising from the kagome lattice of Ti with predominant Ti 3d character. Through our calculations of the Z2 indices, we have identified that the system exhibits topological nontriviality with surface Dirac cones at the Gamma point and a quasi two-dimensional Dirac state at the K point which is further confirmed by our ARPES measured band dispersion. These results establish YbTi3Bi4 as a novel platform for exploring the intersection of nontrivial topology, and electron correlation effects in this newly discovered Ti based kagome lattice.Comment: 8 pages, 5 figure

Observation of flat and weakly dispersing bands in a van der Waals semiconductor Nb3Br8 with breathing kagome lattice

Niobium halides, Nb3X8 (X = Cl,Br,I), which are predicted two-dimensional magnets, have recently gotten attention due to their breathing kagome geometry. Here, we have studied the electronic structure of Nb3Br8 by using angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations. ARPES results depict the presence of multiple flat and weakly dispersing bands. These bands are well explained by the theoretical calculations, which show they have Nb d character indicating their origination from the Nb atoms forming the breathing kagome plane. This van der Waals material can be easily thinned down via mechanical exfoliation to the ultrathin limit and such ultrathin samples are stable as depicted from the time-dependent Raman spectroscopy measurements at room temperature. These results demonstrate that Nb3Br8 is an excellent material not only for studying breathing kagome induced flat band physics and its connection with magnetism, but also for heterostructure fabrication for application purposes.Comment: 24 pages, 12 figures, Supplemental Material include

pH-Stable Zn(II) Coordination Polymer as a Multiresponsive Turn-On and Turn-Off Fluorescent Sensor for Aqueous Medium Detection of Al(III) and Cr(VI) Oxo-Anions

Nowadays, coordination polymers (CPs) are promising candidates as sensory materials for their high sensitivity, improved selectivity, fast responsive nature, as well as good recyclability. However, poor chemical stability often makes their practical usage limited. Herein, employing a mixed ligand approach, we constructed a chemically robust CP, {[Zn2L2(DPA)2]·3H2O}n (IITKGP-70, IITKGP stands for the Indian Institute of Technology Kharagpur), which exhibited excellent framework robustness not only in water but also over a broad range of pH solutions (pH = 3–11). The developed framework displayed high selectivity and sensitivity for the detection of trivalent Al3+ ions and toxic hexavalent Cr(VI)-oxo anions in an aqueous medium. The developed framework exhibited an aqueous medium Al3+ turn-on phenomenon with a limit of detection (LOD) value of 1.29 μM, whereas a turn-off effect was observed for toxic oxo-anions (Cr2O72– and CrO42–) having LOD values of 0.27 and 0.71 μM, respectively. Both turn-on and turn-off mechanisms are speculated via spectroscopic methods coupled with several ex situ studies. Such a multiresponsive nature (both turn-on and turn-off) for aqueous medium detection of targeted cations and anions simultaneously in a single platform coupled with high robustness, ease of scalability, recyclability, and fast-responsive nature makes IITKGP-70 highly fascinating as a sensory material for real-world applications

Critical perspectives on metal–organic frameworks and their composites for the adsorptive removal of antibiotics from wastewater matrices

Antibiotics have recently emerged as a significant class of organic pollutants for ground and drinking water and have raised widespread concern due to their adverse environmental consequences. For instance, they stimulate the generation of antibiotic-resistant genes that have detrimental effects on the entire biosphere. The removal of these antibiotics from water matrices has always remained a daunting task. Metal–organic frameworks (MOFs) with a high surface area, tunable porosity, rich structural chemistry, and tailorability have grabbed immense attention recently for the efficient adsorptive removal of various antibiotics via strong host–guest interactions. Here, in this Perspective, we have rationally reviewed the state-of-the-art advancements of MOFs and their composites for the adsorptive removal of various antibiotic classes. Moreover, different strategies to improve the adsorption of antibiotics and the factors affecting the adsorption are critically presented. Various types of antibiotics are categorically organized, and their removal with these systems is critically discussed. Advantages and pitfalls of MOFs over other classical porous materials are particularly stated from both academic and industrial viewpoints. Finally, the challenges and future outlook are discussed to guide further development of multifunctional MOF-based materials for the efficient adsorptive removal of various antibiotic classes

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Not AvailableIndigenous folk rice cultivars often possess remarkable but unrevealed potential in terms of nutritional attributes and biotic stress tolerance. The unique cooking qualities and blissful aroma of many of these landraces make it an attractive low-cost alternative to high priced Basmati rice. Sub-Himalayan Terai region is bestowed with great agrobiodiversity in traditional heirloom rice cultivars. In the present study, ninety-nine folk rice cultivars from these regions were collected, purified and characterized for morphological and yield traits. Based on traditional importance and presence of aroma, thirty-five genotypes were selected and analyzed for genetic diversity using micro-satellite marker system. The genotypes were found to be genetically distinct and of high nutritive value. The resistant starch content, amylose content, glycemic index and antioxidant potential of these genotypes represented wide variability and ‘Kataribhog’, ‘Sadanunia’, ‘Chakhao’ etc. were identified as promising genotypes in terms of different nutritional attributes. These cultivars were screened further for resistance against blast disease in field trials and cultivars like ‘Sadanunia’, ‘T4M-3-5’, ‘Chakhao Sampark’ were found to be highly resistant to the blast disease whereas ‘Kalonunia’, ‘Gobindabhog’, ‘Konkanijoha’ were found to be highly susceptible. Principal Component analysis divided the genotypes in distinct groups for nutritional potential and blast tolerance. The resistant and susceptible genotypes were screened for the presence of the blast resistant pi genes and association analysis was performed with disease tolerance. Finally, a logistic model based on phenotypic traits for prediction of the blast susceptibility of the genotypes is proposed with more than 80% accuracy.ICAR, Govt. of India under Niche area of Excellence (NAE) scheme with project reference number Edn.5(12)/2017-EP&H

Triple Framework Interpenetration and Immobilization of Open Metal Sites within a Microporous Mixed Metal–Organic Framework for Highly Selective Gas Adsorption

A three-dimensional triply interpenetrated mixed metal–organic framework, Zn₂(BBA)₂(CuPyen)·G_<i>x</i> (<b>M’MOF-20</b>; BBA = biphenyl-4,4′-dicarboxylate; G = guest solvent molecules), of primitive cubic net was obtained through the solvothermal reaction of Zn­(NO₃)₂, biphenyl-4,4′-dicarboxylic acid, and the salen precursor Cu­(PyenH₂)­(NO₃)₂ by a metallo-ligand approach. The triple framework interpenetration has stabilized the framework in which the activated <b>M’MOF-20a</b> displays type-I N₂ gas sorption behavior with a Langmuir surface area of 62 m² g^–1. The narrow pores of about 3.9 Å and the open metal sites on the pore surfaces within <b>M’MOF-20a</b> collaboratively induce its highly selective C₂H₂/CH₄ and CO₂/CH₄ gas separation at ambient temperature