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991.
Suneesh C. Karunakaran Brian J. Cafferty Angela Weigert‐Muoz Gary B. Schuster Nicholas V. Hud 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1467-1471
Aqueous solutions of the achiral, monomeric, nucleobase mimics (2,4,6‐triaminopyrimidine, TAP, and a cyanuric acid derivative, CyCo6) spontaneously assemble into macroscopic homochiral domains of supramolecular polymers. These assemblies exhibit a high degree of chiral amplification. Addition of a small quantity of one handedness of a chiral derivative of CyCo6 generates exclusively homochiral structures. This system exhibits the highest reported degree of chiral amplification for dynamic helical polymers or supramolecular helices. Significantly, homochiral polymers comprised of hexameric rosettes with structural features that resemble nucleic acids are formed from mixtures of cyanuric acid (Cy) and ribonucleotides (l‐, d ‐pTARC) that arise spontaneously from the reaction of TAP with the sugars. These findings support the hypothesis that nucleic acid homochirality was a result of symmetry breaking at the supramolecular polymer level. 相似文献
992.
Rachel C. Chiaroni‐Clarke Jane E. Munro Angela Pezic Joanna E. Cobb Jonathan D. Akikusa Roger C. Allen Terence Dwyer Anne‐Louise Ponsonby Justine A. Ellis 《Photochemistry and photobiology》2019,95(3):867-873
Cutaneous sun exposure is an important determinant of circulating vitamin D. Both sun exposure and vitamin D have been inversely associated with risk of autoimmune disease. In juvenile idiopathic arthritis (JIA), low circulating vitamin D appears common, but disease‐related behavioral changes may have influenced sun exposure. We therefore aimed to determine whether predisease sun exposure is associated with JIA. Using validated questionnaires, we retrospectively measured sun exposure for 202 Caucasian JIA case–control pairs born in Victoria Australia, matched for birth year and time of recruitment. Measures included maternal sun exposure at 12 weeks of pregnancy and child sun exposure across the life‐course prediagnosis. We converted exposure to UVR dose and looked for case–control differences using logistic regression, adjusting for potential confounders. Higher cumulative prediagnosis UVR exposure was associated with reduced risk of JIA, with a clear dose–response relationship (trend P = 0.04). UVR exposure at 12 weeks of pregnancy was similarly inversely associated with JIA (trend P = 0.011). Associations were robust to sensitivity analyses for prediagnosis behavioral changes, disease duration and knowledge of the hypothesis. Our data indicate that lower UVR exposure may increase JIA risk. This may be through decreased circulating vitamin D, but prospective studies are required to confirm this. 相似文献
993.
Salvatore Spadaro Marco Santoro Francesco Barreca Angela Scala Simona Grimato Fortunato Neri Enza Fazio 《Frontiers of Physics》2018,13(1):136201
A PEGylated-PLGA random nanofibrous membrane loaded with gold and iron oxide nanoparticles and with silibinin was prepared by electrospinning deposition. The nanofibrous membrane can be remotely controlled and activated by a laser light or magnetic field to release biological agents on demand. The nanosystems were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and thermogravimetric analyses. The drug loading efficiency and drug content percentages were determined by UV-vis optical absorption spectroscopy. The nanofibrous membrane irradiated by a relatively low-intensity laser or stimulated by a magnetic field showed sustained silibinin release for at least 60 h, without the burst effect. The proposed low-cost electrospinning procedure is capable of assembling, via a one-step procedure, a stimuli-responsive drug-loaded nanosystem with metallic nanoparticles to be externally activated for controlled drug delivery. 相似文献
994.
Background
Artificial language studies have revealed the remarkable ability of humans to extract syntactic structures from a continuous sound stream by mere exposure. However, it remains unclear whether the processes acquired in such tasks are comparable to those applied during normal language processing. The present study compares the ERPs to auditory processing of simple Italian sentences in native and non-native speakers after brief exposure to Italian sentences of a similar structure. The sentences contained a non-adjacent dependency between an auxiliary and the morphologically marked suffix of the verb. Participants were presented four alternating learning and testing phases. During learning phases only correct sentences were presented while during testing phases 50 percent of the sentences contained a grammatical violation. 相似文献995.
Barty A Marchesini S Chapman HN Cui C Howells MR Shapiro DA Minor AM Spence JC Weierstall U Ilavsky J Noy A Hau-Riege SP Artyukhin AB Baumann T Willey T Stolken J van Buuren T Kinney JH 《Physical review letters》2008,101(5):055501
Ultralow density polymers, metals, and ceramic nanofoams are valued for their high strength-to-weight ratio, high surface area, and insulating properties ascribed to their structural geometry. We obtain the labrynthine internal structure of a tantalum oxide nanofoam by x-ray diffractive imaging. Finite-element analysis from the structure reveals mechanical properties consistent with bulk samples and with a diffusion-limited cluster aggregation model, while excess mass on the nodes discounts the dangling fragments hypothesis of percolation theory. 相似文献
996.
997.
Andresen GB Bertsche W Bowe PD Bray CC Butler E Cesar CL Chapman S Charlton M Fajans J Fujiwara MC Funakoshi R Gill DR Hangst JS Hardy WN Hayano RS Hayden ME Hydomako R Jenkins MJ Jørgensen LV Kurchaninov L Lambo R Madsen N Nolan P Olchanski K Olin A Povilus A Pusa P Robicheaux F Sarid E El Nasr SS Silveira DM Storey JW Thompson RI van der Werf DP Wurtele JS Yamazaki Y;ALPHA Collaboration 《Physical review letters》2008,100(20):203401
Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma. 相似文献
998.
Adamson P Andreopoulos C Arms KE Armstrong R Auty DJ Ayres DS Baller B Barnes PD Barr G Barrett WL Becker BR Belias A Bernstein RH Bhattacharya D Bishai M Blake A Bock GJ Boehm J Boehnlein DJ Bogert D Bower C Buckley-Geer E Cavanaugh S Chapman JD Cherdack D Childress S Choudhary BC Cobb JH Coleman SJ Culling AJ de Jong JK Dierckxsens M Diwan MV Dorman M Dytman SA Escobar CO Evans JJ Harris EF Feldman GJ Frohne MV Gallagher HR Godley A Goodman MC Gouffon P Gran R Grashorn EW Grossman N Grzelak K 《Physical review letters》2008,101(13):131802
This Letter reports new results from the MINOS experiment based on a two-year exposure to muon neutrinos from the Fermilab NuMI beam. Our data are consistent with quantum-mechanical oscillations of neutrino flavor with mass splitting |Deltam2| = (2.43+/-0.13) x 10(-3) eV2 (68% C.L.) and mixing angle sin2(2theta) > 0.90 (90% C.L.). Our data disfavor two alternative explanations for the disappearance of neutrinos in flight: namely, neutrino decays into lighter particles and quantum decoherence of neutrinos, at the 3.7 and 5.7 standard-deviation levels, respectively. 相似文献
999.
This paper presents results for matched field Bayesian geoacoustic inversion of multitonal continuous wave data collected on the New Jersey continental shelf. To account for effects of significant spatial and temporal variation of the water column sound speed, the sound speed profile was represented by empirical orthogonal functions. Data error information for the inversion was estimated from multiple time windows of the data. Inversion results for the sediment sound speeds at three ranges are in excellent agreement with the ground truth. 相似文献
1000.