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91.
Gianfranco Denti Scolastica Serroni Giovanni Sindona Nicola Uccella 《Journal of the American Society for Mass Spectrometry》1993,4(4):306-311
Fast-atom bombardment (FAB) mass spectrometry in the negative ionization mode enables the sputtering into the gas phase of the ruthenium complexes [Ru(2,2′-bipyridine[bpy])2(2,5-bis) (pyrydil)pyrazine[dpp])](PF6)2; [Ru(bpy)2,(2,3dpp)](PF6)2;[Ru(bpy)2,(2,3-dpp-Me)]( PF6)3; and [Ru(bpy)2(?-2,3-dpp)]2 RuCl2(PF6)4 as intact radical anions. These data, combined with those avaiiable from the positive FAB spectra allow a full characterization of the analytes. 相似文献
92.
Herman Bachelard Peter Morris Andrew Taylor Nicola Thatcher 《Magnetic resonance imaging》1995,13(8):1223-1226
We are applying multi-nuclear high-field (500 MHz) MR spectroscopy of metabolising whole tissue preparations of the mammalian brain to studies on individual components of convulsions, which include prolonged depolarization, metabolic deprivation, and the effects of excitotoxins. The responses of glial cells and neurones can be partially distinguished by following labelling patterns of metabolic intermediates from 13C-labelled glucose or acetate (which enters only glial cells). This approach clearly confirmed our earlier indications that the metabolic response to depolarization (40 mM extracellular K+) occurs essentially in glial cells. Some evidence for metabolic shuttling between glia and neurones was obtained from the changes in C3/C4 ratios of glutamate and glutamine, and the C2/C3 of GABA. Mechanisms for metabolic support of neurones by glia may be of importance in neuronal protection under such metabolic stress as occurs in epilepsy. Changes in free intracellular divalent cations ([Ca2+]i and [Zn2+]i) were monitored using the 19F-MRS indicator, 5FBAPTA. Large increases in [Ca2+]i and decreases in PCr were produced by excitotoxins (glutamate and NMDA), depolarization or ischaemia, but intracellular Zn2+ appeared only after exposure to the excitotoxins. The NMDA receptor blocker, MK801, removed all of the responses to NMDA, but only prevented the appearance of Zn2+ observed with glutamate. These results indicate that the damage caused to neurones by such insults as convulsions is not due simply to the presence of excessive excitotoxic glutamate. 相似文献
93.
Eric Mayer-Santos Tatjana Maravic Allegra Comba Patricia Moreira Freitas Giovanna Bueno Marinho Claudia Mazzitelli Edoardo Mancuso Nicola Scotti Federica Florenzano Lorenzo Breschi Annalisa Mazzoni 《Molecules (Basel, Switzerland)》2022,27(5)
This study aimed to investigate matrix metalloproteinase (MMP) activity in human dentin using in-situ and gelatin zymography, after at-home and in-office bleaching, related to their clinical exposure times. Dentin specimens (n = 5) were treated with 35% hydrogen peroxide (50 min per session/4 sessions), 10% carbamide peroxide (180 min/21 sessions), or no treatment. All were subjected to in-situ zymography. Dentin slices were, subsequently, obtained, covered with fluorescein-conjugated gelatin, and examined with confocal laser-scanning microscopy. The fluorescence intensity was quantified and statistically analyzed using one-way ANOVA and Bonferroni tests (α = 0.05). Furthermore, gelatin zymography was performed on protein extracts obtained from dentin powder (N = 8 teeth), treated with hydrogen peroxide or carbamide peroxide, with different exposure times (10/50 min for hydrogen peroxide; 252/1260 min for carbamide peroxide). The results of the in-situ zymography showed no statistical differences between the bleached specimens and the control group, with a medium level of gelatinolytic activity expressed in the dentin tubules. The results of gelatin zymography showed an increased expression of pro-MMP-9 in carbamide peroxide groups. The expression of pro-MMP-2 decreased in all the experimental groups. The bleaching treatments performed on the enamel of sound teeth do not influence dentinal enzymatic activity. However, when unprotected dentin tissue is bleached, matrix metalloproteinases are more expressed, particularly when carbamide peroxide is used, proportional to the exposure time. 相似文献
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96.
Nicola Maria Pugno 《Journal of the mechanics and physics of solids》2010,58(9):1397-1410
The study reported in this paper suggests that the influence of the surrounding nanotubes in a bundle is nearly identical to that of a liquid having surface tension equal to the surface energy of the nanotubes. This surprising behaviour is supported by the calculation of the polygonization and especially of the self-collapse diameters, and related dog-bone configurations, of nanotubes in a bundle, in agreement with atomistic simulations and nanoscale experiments. Accordingly, we have evaluated the strength of the nanotube bundle, with or without collapsed nanotubes, assuming a sliding failure: the self-collapse can increase the strength up to a value of about ∼30%, suggesting the design of self-collapsed super-strong nanotube bundles.Other systems, such as peapods and fullerites, can be similarly treated, including the effect of the presence of a liquid, as reported in the appendices. 相似文献
97.
Nicola Oberbeckmann-Winter 《Analytical and bioanalytical chemistry》2012,403(8):2069-2070
98.
Valentino Magnani 《Calculus of Variations and Partial Differential Equations》2010,39(1-2):233-271
We characterize locally Lipschitz mappings and existence of Lipschitz extensions through a first order nonlinear system of PDEs. We extend this study to graded group-valued Lipschitz mappings defined on compact Riemannian manifolds. Through a simple application, we emphasize the connection between these PDEs and the Rumin complex. We introduce a class of 2-step groups, satisfying some abstract geometric conditions and we show that Lipschitz mappings taking values in these groups and defined on subsets of the plane admit Lipschitz extensions. We present several examples of these groups, called Allcock groups, observing that their horizontal distribution may have any codimesion. Finally, we show how these Lipschitz extensions theorems lead us to quadratic isoperimetric inequalities in all Allcock groups. 相似文献
99.
Inês R. Ramos Fiona M. Lyng Ihtesham Ur Rehman Basil Sharrack M. Nicola Woodroofe 《应用光谱学评论》2017,52(10):868-882
Spectroscopy techniques are valuable tools in biomedical research and have been used extensively in the study of disease. However, neurological conditions such as multiple sclerosis (MS) have received little attention and the available spectroscopy studies are limited, both in overall numbers of patients studied and the disease samples considered. MS is a complex immune-mediated disease, with variable clinical courses and limited therapeutic options. This review aims to summarize current literature in the area, demonstrating how spectroscopy techniques can provide valuable information to inform and advance research into the most common neurological condition affecting young adults. 相似文献
100.
Novel intramolecular TaqMan probes have been evaluated on the W1282X locus of the human ABCC7 gene and shown to be more efficient than traditional TaqMan probes. 相似文献