02021nas a2200277   4500008004100000022001400041245012300055210006900178260009800247300001200345490000700357520099700364653002901361653002901390653002701419653001001446653002301456653002001479653001001499653000901509100002701518700001701545700002201562700002901584856013001613       2008                        eng d  a0749-158100aHeteronuclear dipolar decoupling effects on multiple-quantum and satellite-transition magic-angle spinning NMR spectra0 aHeteronuclear dipolar decoupling effects on multiplequantum and   aTHE ATRIUM, SOUTHERN GATE, CHICHESTER PO19 8SQ, W SUSSEX, ENGLANDbJOHN WILEY & SONS LTDcOCT  a948-9540 v463 a<p>We here report on the influence of heteronuclear dipolar decoupling on the Al-27 3QMAS, 5QMAS, and the double-quantum filter-satellite-transition magic-angle spinning (DQF-STMAS) spectra of a strongly dipolar-coupled system, gibbsite. The requirements for heteronuclear dipolar decoupling increase with the order of coherence evolving in the indirect dimension of a two-dimensional (2D) experiment. The isotropic line width of the high-resolution 2D spectra, in samples like gibbsite, is composed of four parts: the distribution of isotropic shifts (delta(ISO), delta(QIS)), the homogeneous broadening related to the proton-proton flip-flop terms, the Al-27-Al-27 homonulcear dipolar couplings, and the H-1-Al-27 heteronuclear dipolar couplings. It is shown that, even in the case of gibbsite, where a strong proton-proton bath exists, the main resolution limiting factor in these experiments resides in the H-1-Al-27 dipolar interaction. Copyright (C) 2008 John Wiley &amp; Sons, Ltd.</p>10aheteronuclear broadening10aheteronuclear decoupling10ahomogeneous broadening10aMQMAS10aquadrupolar nuclei10aSolid-state NMR10aSTMAS10aTPPM1 aGanapathy, Subramanian1 aDelevoye, L.1 aArnoureux, J., P.1 aMadhu, Perunthiruthy, K.  uhttps://library.ncl.res.in/content/heteronuclear-dipolar-decoupling-effects-multiple-quantum-and-satellite-transition-magic-001530nas a2200193   4500008004100000022001400041245013200055210006900187260007300256300001200329490000800341520074800349100001601097700002901113700001601142700002001158700002701178856013101205       2009                        eng d  a0009-261400aSensitivity enhancement of Si-29 double-quantum dipolar recoupling spectroscopy by Carr-Purcell-Meiboom-Gill acquisition method0 aSensitivity enhancement of Si29 doublequantum dipolar recoupling  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG  a287-2910 v4783 a<p>An enhancement in the detection sensitivity of dipolar recoupled Si-29 double-quantum magic-angle spinning experiment is shown with a Carr-Purcell-Meiboom-Gill (CPMG) train of pi pulses during the acquisition period. Symmetry-adapted pulse schemes, such as POST-C7 and SR26(4)(11), are used for the double-quantum excitation. Application of POST-C7-CPMG method for framework characterisation is demonstrated in the disordered and catalytically important ZSM-5 molecular sieve. Based on the observed double-quantum dipole-dipole correlations and the known T-site Si connectivities, the assignment of all the signals is made for the orthorhombic phase of the as-synthesised (CN form) material. (C) 2009 Elsevier B. V. All rights reserved.</p>1 aGoswami, M.1 aMadhu, Perunthiruthy, K.1 aDittmer, J.1 aNielsen, N., C.1 aGanapathy, Subramanian  uhttps://library.ncl.res.in/content/sensitivity-enhancement-si-29-double-quantum-dipolar-recoupling-spectroscopy-carr-purcell-001993nas a2200265   4500008004100000022001400041245013600055210006900191260010600260300001200366490000800378520095700386653002001343653001001363653003101373653002401404100002101428700002301449700002001472700002301492700002901515700003201544700002501576856012601601       2010                        eng d  a0038-109800aEvidence for the co-existence of distorted tetrahedral and trigonal bipyramidal aluminium sites in SrAl12O19 from Al-27 NMR studies0 aEvidence for the coexistence of distorted tetrahedral and trigon  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJAN  a262-2660 v1503 a<p>Strontium aluminate, SrAl12O19, is a ceramic material having the hexagonal magnetoplumbite-type structure, with multiple Al coordination environments. An earlier low-field Al-27 solid-state NMR study reported five different Al sites in this system: one AlO4, one AlO5, and three AlO6 sites; whereas a later high-field study showed that the AlO5 site is a distorted AlO4 site with a very large quadrupolar coupling constant (similar to 20 MHz). Our magic angle spinning (MAS) and 3-quantum magic angle spinning (3QMAS) NMR studies at 7.05 T unambiguously show evidence for an AlO5 site. However, evidence for the presence of a distorted AlO4 site is obtained from studies at high fields (16.4 and 17.6 T), in addition to the AlO5 site. Thus the present solid-state NMR studies give evidence for the simultaneous presence of both the five-coordinated and distorted four-coordinated sites in this system. (C) 2009 Elsevier Ltd. All rights reserved.</p>10aLocal structure10aMQMAS10aNuclear magnetic resonance10aStrontium aluminate1 aHarindranath, K.1 aViswanath, Anusree1 aChandran, Vinod1 aBraeuniger, Thomas1 aMadhu, Perunthiruthy, K.1 aAjithkumar, Thalasseril, G.1 aJoy, Pattayil, Alias  uhttps://library.ncl.res.in/content/evidence-co-existence-distorted-tetrahedral-and-trigonal-bipyramidal-aluminium-sites-002291nas a2200361   4500008004100000022001400041245011000055210006900165260007300234300001000307490000800317520103700325653002401362653004201386653002401428653002001452100003101472700001901503700002401522700002501546700002201571700001501593700002201608700001701630700001801647700001901665700002201684700001901706700002501725700002901750700001901779856013101798       2013                        eng d  a0301-010400aBasic structural motif and major biophysical properties of Amyloid-beta are encoded in the fragment 18-350 aBasic structural motif and major biophysical properties of Amylo  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG  a80-870 v4223 a<p>Aggregation and misfolding of the amyloid beta (A beta) peptide is thought to initiate Alzheimer's disease (AD). Here we study the role played by its central segment (A beta(18-35)) in determining these properties. A beta(18-35) has a solubility of 18 mu M. The soluble fraction consists mainly of small oligomers, which have mixed beta-sheet and random coil structures. The monomer is mostly a random coil with some residual compactness. Aggregated A beta(18-35) forms fibrils of width 3.0 +/- 0.7 nm, which is consistent with a hairpin shape. Each of these properties has a close similarity to A beta(40). Remarkably, solid state NMR indicates that the fibrils also retain the secondary structure and tertiary contacts of A beta(40). This is the shortest fragment of A beta reported so far which preserves its fibrillar architecture, including the hairpin turn, as well as its solution phase conformational properties. Residues 18-35 should therefore be a key target of AD therapeutics. (C) 2013 Published by Elsevier B. V.</p>10aAlzheimer's disease10aFluorescence correlation spectroscopy10aProtein aggregation10aSolid-state NMR1 aChandrakesan, Muralidharan1 aSarkar, Bidyut1 aMithu, Venus, Singh1 aAbhyankar, Rajiv, M.1 aBhowmik, Debanjan1 aNag, Suman1 aSahoo, Bankanidhi1 aShah, Riddhi1 aGurav, Sushma1 aBanerjee, Raja1 aDandekar, Sucheta1 aJose, Jaya, C.1 aSengupta, Neelanjana1 aMadhu, Perunthiruthy, K.1 aMaiti, Sudipta  uhttps://library.ncl.res.in/content/basic-structural-motif-and-major-biophysical-properties-amyloid-beta-are-encoded-fragment-001374nas a2200253   4500008004100000022001400041245010500055210006900160260007700229300001400306490000700320520041200327653002800739653001900767653002100786653003100807653002700838100001900865700002300884700003000907700002900937700002400966856013000990       2015                        eng d  a1433-785100aSBA-15-oxynitrides as a solid-base catalyst: effect of nitridation temperature on catalytic activity0 aSBA15oxynitrides as a solidbase catalyst effect of nitridation t  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcMAY  a5985-59890 v543 a<p>Solid bases, such as SBA-15-oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid-state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity.</p>10aheterogeneous catalysis10aNanostructures10aNMR spectroscopy10aphotoelectron spectroscopy10asolid-state structures1 aSingh, Baljeet1 aMote, Kaustubh, R.1 aGopinath, Chinnakonda, S.1 aMadhu, Perunthiruthy, K.1 aPolshettiwar, Vivek  uhttps://library.ncl.res.in/content/sba-15-oxynitrides-solid-base-catalyst-effect-nitridation-temperature-catalytic-activity-001919nas a2200193   4500008004100000022001400041245008900055210006900144260000800213300001600221490000800237520125000245100001401495700002301509700001901532700002901551700002501580856012001605       2021                        eng d  a1932-744700aPhotoactive anthraquinone-based host-guest assembly for long-lived charge separation0 aPhotoactive anthraquinonebased hostguest assembly for longlived   cMAY  a10891-109000 v1253 aPorous 2D covalent organic frameworks (COF) that are assembled axially through weak p-stacking interactions can provide reticular charge transport channels while playing host to kinetically stabilized reactive molecular redox states. Here we demonstrate a host-guest supramolecular charge transfer (CT) assembly using photoactive anthraquinone-based COF as an acceptor while incarcerating the electron donor N,N-dimethylaniline (DMA) inside it. Employing femtosecond broadband transient absorption spectroscopy in combination with electron paramagnetic resonance (EPR) studies, we show that the CT occurs rapidly within <110 fs after photoexcitation, subsequently leading to long-lived charge separation with 13% quantum efficiency at room temperature. The photoinduced EPR signature of the long-lived confined DMA cation radical confirms the disparate regions of charge localization while H-1-C-13 correlation experiments using solid-state NMR spectroscopy enumerate the packing of the amines inside the host-guest COF assembly. Our work demonstrates the potency of charge transport pathways in supramolecular assemblies for efficient charge separation which if optimally tuned should pave the way for COF-based photocatalytic reaction centers.1 aJha, Ajay1 aMote, Kaustubh, R.1 aChandra, Suman1 aMadhu, Perunthiruthy, K.1 aDasgupta, Jyotishman  uhttps://library.ncl.res.in/content/photoactive-anthraquinone-based-host-guest-assembly-long-lived-charge-separation