<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

(SoNS) School of Natural Sciences

Magnetization, resistivity and 11B, 59Co NMR measurements have been performed on the Pauli paramagnet and the superconductors La0.9Y0.1Co2B2 (Tc≈4.2 K) and La(Co0.7Fe0.3)2B2 (Tc≈5.8 K). The site selective NMR experiment reveals the multiband nature of the Fermi surface in these systems. The temperature independent Knight shift and 1/T 1 T clearly indicate the absence of correlated low energy magnetic spin-fluctuations in the normal state, which is in contrast to other Fe-based pnictides. The density of states (DOS) of Co 3d electrons has been enhanced in superconducting La0.9Y0.1Co2B2 and La(Co0.7Fe0.3)2B2 with respect to the non superconducting reference compound LaCo2B2. The occurrence of superconductivity is related to the DOS enhancement.

Physics

World University root node

Journal of Physics Condensed Matter

Absence of low energy magnetic spin-fluctuations in isovalently and aliovalently doped LaCo2B2 superconducting compounds

This paper deals with the preparation of sustainable benzoxazines that exhibit enormous potential to compete with the existing petro-based advance performance thermosets. The phenolic component used for the synthesis of benzoxazine is derived from naturally occurring cardanol, which is obtained from cashew nut tree, Anacardium occidentale. Polyethylene terephthalate (PET) was chosen as a sustainable feedstock for the amine fraction used to prepare the benzoxazine monomer containing amide linkages. Microwave-assisted aminolysis of PET was performed to obtain bis(amino-ethyl) terephthalamide (BAET) and α,ω-aminoligo(ethylene terephthalamide) (AOET), which were employed as the difunctional amine for the preparation of bis-benzoxazines. In comparison to the traditional method, microwave-assisted aminolysis of PET was found to be significantly faster, and the reaction completion time could be brought down appreciably. Mannich-like condensation of cardanol with PET-derived terephthalamides and paraformaldehyde led to the formation of bis-benzoxazines with amide linkages, the structure of which was confirmed through FT-IR and 1H NMR spectroscopy. The curing behavior of the bis-benzoxazines was studied using nonisothermal differential scanning calorimetry. The presence of amide linkages in addition to the polar group formed during the ring opening of benzoxazines led to the improvement in adhesive strength, which was quantified in terms of lap shear strength. © 2015 American Chemical Society.

Chemistry

ACS Sustainable Chemistry and Engineering

Sustainable Bis-benzoxazines from Cardanol and PET-Derived Terephthalamides

Herein, we report a facile synthesis of 3,4-dihydro-β-carbolines and aromatic β-carbolines from tetrahydro-β-carbolines, mediated by N-bromosuccinimide in toluene at 0°C to room temperature (rt), in good to moderate yields. © 2016 Elsevier Ltd. All rights reserved.

Tetrahedron Letters

N-Bromo-succinimide promoted synthesis of β-carbolines and 3,4-dihydro-β-carbolines from tetrahydro-β-carbolines

Transformation of self-assembled crystalline TiO2 nanorods to amorphous layer, and the corresponding impact on optical-bandgap (Eg) on Si pyramids are investigated by irradiating with 50 keV Ar+-ions. Initially, Eg is found to be reduced from 3.23 to 2.94 eV up to a fluence of 1 × 1016 ions/cm2, and discussed in terms of the rise in oxygen vacancies (VO). However, a sudden increase in Eg to 3.38 eV is detected at a fluence of 1 × 1017 ions/cm2 through evolution of voids by over-saturating VO, manifesting the appearance of degenerate states by shifting the Fermi level above the conduction band minimum via Burstein-Moss effect. © 2016 AIP Publishing LLC.

Fulltext

Applied Physics Letters

Defect-engineered optical bandgap in self-assembled TiO2 nanorods on Si pyramids

Saturation magnetization (Ms) of pristine bi-/tri-layered graphene (denoted as-FLG) is enhanced by over four (4) and thirty-four (34) times to 13.94 × 10-4 and 118.62 × 10-4 emu g-1, respectively, as compared to pristine FLGs (Ms of 3.47 × 10-4 emu g-1), via plasma-based-hydrogenation (known as graphone) and nitrogenation (known as N-graphene) reactions, respectively. However, upon organo-silane treatment on FLG (known as siliphene), the saturation magnetization is reduced by over thirty (30) times to 0.11 × 10-4 emu g-1, as compared to pristine FLG. Synchrotron based X-ray absorption near edge structure spectroscopy measurements have been carried out to investigate the electronic structure and the underlying mechanism responsible for the variation of magnetic properties. For graphone, the free spin available via the conversion of the sp2 → sp3 hybridized structure and the possibility of unpaired electrons from induced defects are the likely mechanism for ferromagnetic ordering. During nitrogenation, the Fermi level of FLGs is shifted upwards due to the formation of a graphitic like extra π-electron that makes the structure electron-rich, thereby, enhancing the magnetic coupling between magnetic moments. On the other hand, during the formation of siliphene, substitution of the C-atom in FLG by a Si-atom occurs and relaxes out the graphene plane to form Si-C tetrahedral sp3-bonding with a non-magnetic atomic arrangement showing no spin polarization phenomena and thereby reducing the magnetization. Thus, plasma functionalization offers a simple yet facile route to control the magnetic properties of the graphene systems and has potential implications for spintronic applications. © 2016 The Royal Society of Chemistry.

RSC Advances

Plasma modification of the electronic and magnetic properties of vertically aligned bi-/tri-layered graphene nanoflakes

Three isostructural polymorphs with two-dimensional and three-dimensional similarities are demonstrated quantitatively from similarity relationship analysis. The similarity dimensions are then visualized and correlated in a novel way via qualitative analysis using 'energy frameworks'. Two of the three polymorphs with three-dimensional similarities exhibiting identical physical properties have almost equi-energetic crystal structures while the most stable third polymorph exhibits distinct properties. Thereby, structure-property correlations are derived, both quantitatively and qualitatively. © 2016 The Royal Society of Chemistry.

CrystEngComm

Isostructural polymorphs: Qualitative insights from energy frameworks

Range and magnitude of electric fields at biomolecular interfaces and their fluctuations in a time window down to the subpicosecond regime have remained controversial, calling for electric-field mapping in space and time. Here, we trace fluctuating electric fields at the surface of native salmon DNA via their interactions with backbone vibrations in a wide range of hydration levels by building the water shell layer by layer. Femtosecond two-dimensional infrared spectroscopy and ab initio based theory establish water molecules in the first two layers as the predominant source of interfacial electric fields, which fluctuate on a 300 fs time scale with an amplitude of 25 MV/cm due to thermally excited water motions. The observed subnanometer range of these electric interactions is decisive for biochemical structure and function. © 2016 American Chemical Society.

Journal of Physical Chemistry Letters

Range, Magnitude, and Ultrafast Dynamics of Electric Fields at the Hydrated DNA Surface

Noreremophilanes are a rare class of cis-hydrindanes produced by genus Ligularia herbaceous plants which are known to exhibit interesting biological activities. We synthesized cis-hydrindanes based on a naturally occurring noreremophilane scaffold using a Diels-Alder/aldol sequence and screened them for multiple biological activities using high-content zebrafish embryonic development assays. We discovered a noreremophilane that has strong anti-angiogenic effects on the developing zebrafish embryos as well as on tumor-induced angiogenesis in a zebrafish xenograft model. We synthesized several derivatives of this class of noreremophilanes and performed structure-activity relationship studies in zebrafish to identify more potent and less toxic analogs of the original structure. © The Royal Society of Chemistry 2016.

Life Sciences

Organic and Biomolecular Chemistry

Identification of noreremophilane-based inhibitors of angiogenesis using zebrafish assays

Mutant Huntingtin (mtHtt) causes neurodegeneration in Huntington's disease (HD) by evoking defects in the mitochondria, but the underlying mechanisms remains elusive. Our proteomic analysis identifies valosin-containing protein (VCP) as an mtHtt-binding protein on the mitochondria. Here we show that VCP is selectively translocated to the mitochondria, where it is bound to mtHtt in various HD models. Mitochondria-accumulated VCP elicits excessive mitophagy, causing neuronal cell death. Blocking mtHtt/VCP mitochondrial interaction with a peptide, HV-3, abolishes VCP translocation to the mitochondria, corrects excessive mitophagy and reduces cell death in HD mouse- and patient-derived cells and HD transgenic mouse brains. Treatment with HV-3 reduces behavioural and neuropathological phenotypes of HD in both fragment- and full-length mtHtt transgenic mice. Our findings demonstrate a causal role of mtHtt-induced VCP mitochondrial accumulation in HD pathogenesis and suggest that the peptide HV-3 might be a useful tool for developing new therapeutics to treat HD.

Nature Communications

VCP recruitment to mitochondria causes mitophagy impairment and neurodegeneration in models of Huntington's disease

Aminotransferases of subfamily I$\beta$, which include histidinol phosphate aminotransferases (HspATs) and aromatic amino acid aminotransferases (ArATs), are structurally similar but possess distinct substrate specificities. This study, encompassing structural and biochemical characterisation of HspAT and ArAT from Mycobacterium tuberculosis demonstrates that the residues lining the substrate binding pocket and N-terminal lid are the primary determinants of their substrate specificities. In mHspAT, hydrophilic residues in the substrate binding pocket and N-terminal lid allow the entry and binding of its preferential substrate, Hsp. On the other hand, the hydrophobic nature of both the substrate binding pocket and the N-terminal lid of mArAT is responsible for the discrimination of a polar substrate such as Hsp, while facilitating the binding of Phe and other aromatic residues such as Tyr and Trp. In addition, the present study delineates the ligand induced conformational rearrangements, providing insights into the plasticity of aminotransferases. Furthermore, the study also demonstrates that the adventitiously bound ligand 2-(N-morpholino)ethanesulfonic acid (MES) is indeed a specific inhibitor of HspAT. These results suggest that previously untapped morpholine-ring scaffold compounds could be explored for the design of new anti-TB agents.