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2.
da Silva Andre Luis Ferreira Salas Ruben Andres Silva Emilio Carlos Nelli 《Meccanica》2021,56(2):417-437
Meccanica - Fiber reinforced materials are used in assorted engineering application and for this reason, new additive manufacturing technologies have been developed for this type of materials. With... 相似文献
3.
Yalda Liaghati Mobarhan Ronald Soong Daniel Lane Andre J. Simpson 《Magnetic resonance in chemistry : MRC》2020,58(5):427-444
Traditionally, due to different hardware requirements, nuclear magnetic resonance (NMR) has developed as two separate fields: one dealing with solids, and one with solutions. Comprehensive multiphase (CMP) NMR combines all electronics and hardware (magic angle spinning [MAS], gradients, high power Radio Frequency (RF) handling, lock, susceptibility matching) into a universal probe that permits a comprehensive study of all phases (i.e., liquid, gel-like, semisolid, and solid), in intact samples. When applied in vivo, it provides unique insight into the wide array of bonds in a living system from the most mobile liquids (blood, fluids) through gels (muscle, tissues) to the most rigid (exoskeleton, shell). In this tutorial, the practical aspects of in vivo CMP NMR are discussed including: handling the organisms, rotor preparation, sample spinning, water suppression, editing experiments, and finishes with a brief look at the potential of other heteronuclei (2H, 15N, 19F, 31P) for in vivo research. The tutorial is aimed as a general resource for researchers interested in developing and applying MAS-based approaches to living organisms. Although the focus here is CMP NMR, many of the approaches can be adapted (or directly applied) using conventional high-resolution magic angle spinning, and in some cases, even standard solid-state NMR probes. 相似文献
4.
Tatiana Monaretto Andre Souza Tiago Bueno Moraes Victor Bertucci-Neto Corinne Rondeau-Mouro Luiz Alberto Colnago 《Magnetic resonance in chemistry : MRC》2019,57(9):616-625
The traditional way to enhance signal-to-noise ratio (SNR) of nuclear magnetic resonance (NMR) signals is to increase the number of scans. However, this procedure increases the measuring time that can be prohibitive for some applications. Therefore, we have tested the use of several post-acquisition digital filters to enhance SNR up to one order of magnitude in time domain NMR (TD-NMR) relaxation measurements. The procedures were studied using continuous wave free precession (CWFP-T1) signals, acquired with very low flip angles that contain six times more noise than the Carr–Purcell–Meiboom–Gill (CPMG) signal of the same sample and experimental time. Linear (LI) and logarithmic (LO) data compression, low-pass infinity impulse response (LP), Savitzky–Golay (SG), and wavelet transform (WA) post-acquisition filters enhanced the SNR of the CWFP-T1 signals by at least six times. The best filters were LO, SG, and WA that have high enhancement in SNR without significant distortions in the ILT relaxation distribution data. Therefore, it was demonstrated that these post-acquisition digital filters could be a useful way to denoise CWFP-T1, as well as CPMG noisy signals, and consequently reducing the experimental time. It was also demonstrated that filtered CWFP-T1 method has the potential to be a rapid and nondestructive method to measure fat content in beef and certainly in other meat samples. 相似文献
5.
Florin Radu Alexei Nefedov Johannes GrabisGregor Nowak Andre BergmannHartmut Zabel 《Journal of magnetism and magnetic materials》2006
We have used soft X-ray resonant magnetic scattering (XRMS) to search for the presence of an effective ferromagnetic moment belonging to the antiferromagnetic (AF) layer which is in close contact with a ferromagnetic (F) layer. Taking advantage of the element specificity of the XRMS technique, we have measured hysteresis loops of both Fe and CoO layers of a CoO(40 Å)/Fe (150 Å) exchange bias bilayer. From these measurements we have concluded that the proximity of the F layer induces a magnetic moment in the AF layer. The F moment of the AF layer has two components: one is frozen and does not follow the applied magnetic field and the other one follows in phase the ferromagnetic magnetization of the F layer. The temperature dependence of the F components belonging to the AF layer is shown and discussed. 相似文献
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7.
We report the synthesis, characterization, thermal and dilute-solution properties of zwitterionic copolymers of the sulfobetaine type, where the proportion of ionic groups is varied over a wide range. Two different structures are considered: poly (2-vinyl pyridine sulfopropyl betaine) and poly (4-vinyl pyridine sulfopropyl betaine). Synthesis is carried out to obtain random copolymers which are further characterized and their ionic content determined. At low proportions of ionic groups, the behavior is similar to that observed in ionomers, with substantial differences between the two structures, Increased interaction among the zwitterionic groups at higher charge densities is evidenced, which leads to the formation of clusters and agglomerates. An increase in the intrinsic viscosity with salt content in aqueous solutions is also observed. This behavior is analogous to that of homopolymers with 100% ionic content, but with particular features of interest. 相似文献
8.
J. G. Cardoso 《International Journal of Theoretical Physics》1997,36(7):1641-1649
A set of simple identities is utilized to build up new projective twistor diagrams for massless free fields of arbitrary spin
in real Minkowski space. It is effectively shown that the inner structure of the configurations which arise out of implementing
the relevant techniques has characteristics that are different from those of the conventional diagrams associated with the
Kirchoff-D'Adhemar-Penrose integral expressions. A nonhomogeneous version of the configurations is also provided. 相似文献
9.
Gerhard Laus Johannes Schütz Herwig Schottenberger Max Andre Klaus Wurst Mariana Spetea Karl‐Hans Ongania AdrianG. Müller Helmut Schmidhammer 《Helvetica chimica acta》2003,86(10):3274-3280
The two diastereoisomeric ferrocenyl‐substituted orvinols 2 and 3 were prepared. The modified alkaloids are still able to interact with opioid receptors (see Table). The ferrocene moiety allows highly selective and sensitive electrochemical detection. The X‐ray crystal structure of the major isomer 2 was determined. The combination of a metallocene and a morphinan alkaloid holds promise for useful antitumor activity. 相似文献
10.
Andre Rosowsky Katherine K. N. Chen Nickolas Papathanasopoulos Edward J. Modest 《Journal of heterocyclic chemistry》1972,9(2):263-273
Eighteen new 1,3-diamino-5,6-dihydrobenzo[f] quinazolines ( 6 , R. = alkyl, Cl, MeO) were synthesized via the condensation of appropriate 2-tetralones with cyanoguanidine under fusion conditions. Methods were developed for the preparation of a number of heretofore undescribed 2-tetralones as precursors. The final products can be viewed as conformationally rigid analogs of pyrimethamine ( 2 ), and are of interest as inhibitors of dihydrofolate reductase and as potential antimalarial and antitumor agents. 相似文献