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221.
C N Davids P J Woods D Seweryniak A A Sonzogni J C Batchelder C R Bingham T Davinson D J Henderson R J Irvine G L Poli J Uusitalo W B Walters 《Pramana》1999,53(3):631
The proton drip line defines one of the fundamental limits to nuclear stability. Nuclei lying beyond this line are energetically
unbound to the emission of a constituent proton from their ground states.
For near-spherical nuclei in the region of the drip line between Z=69 (Tm) and Z=81 (T1), proton decay transition rates have been shown to be well reproduced by WKB calculations using spectroscopic factors
derived from a low-seniority shell model calculation [2]. Another approach using spectroscopic factors obtained from the independent
quasiparticle approximation has also proved successful in this region [3]. These interpretations have allowed the extraction
of nuclear structure information from nuclei well beyond the proton drip line.
The rare-earth proton emitters 141Ho and 131Eu have recently been observed [4], and their decay rates can only be explained by assuming large deformation for these nuclei.
In addition to providing information on the wavefunctions and deformations of these nuclei, these results offer the opportunity
to study the phenomenon of quantum mechanical tunneling through a deformed potential barrier.
Work supported by the U.S. Department of Energy, Nuclear Physics Division, under contract W-31-109-ENG-38. 相似文献
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223.
The scavenging activity of hydroxyl radicals, produced by the Fenton reaction, is commonly used to quantify the antioxidant capacity of plant extracts. In this study, three Fenton systems (Fe/phosphate buffer, Fe/quinolinic acid and Fe/phosphate buffer/quinolinic acid) and the thermal degradation of peroxydisulfate were used to produce hydroxyl radicals; the hydroxyl radical scavenging activity of plant extracts (ginger, blueberry juices and green tea infusion) and chemical compounds (EGCG and GA) was estimated by spin trapping with DMPO (5,5-dimethyl-1-pyrroline N-oxide) and EPR (Electron Paramagnetic Resonance) spectroscopy. Phosphate buffer was used to mimic the physiological pH of cellular systems, while quinolinic acid (pyridine-2,3-dicarboxylic acid) facilitates the experimental procedure by hindering the spontaneous oxidation of Fe(II). The EC50 (the concentration of chemical compounds or plant extracts which halves the intensity of the DMPO–OH adduct) values were determined in all the systems. The results show that, for both the chemical compounds and the plant extracts, there is not a well-defined order for the EC50 values determined in the four hydroxyl radical generating systems. The interactions of phosphate buffer and quinolinic acid with the antioxidants and with potential iron-coordinating ligands present in the plant extracts can justify the observed differences. 相似文献
224.
Marco Ciulu Elisa Oertel Rosanna Serra Roberta Farre Nadia Spano Marco Caredda Luca Malfatti Gavino Sanna 《Molecules (Basel, Switzerland)》2021,26(1)
Nowadays, the mislabeling of honey floral origin is a very common fraudulent practice. The scientific community is intensifying its efforts to provide the bodies responsible for controlling the authenticity of honey with fast and reliable analytical protocols. In this study, the classification of various monofloral honeys from Sardinia, Italy, was attempted by means of ATR-FTIR spectroscopy and random forest. Four different floral origins were considered: strawberry-tree (Arbutus Unedo L.), asphodel (Asphodelus microcarpus), thistle (Galactites tormentosa), and eucalyptus (Eucalyptus calmadulensis). Training a random forest on the infrared spectra allowed achieving an average accuracy of 87% in a cross-validation setting. The identification of the significant wavenumbers revealed the important role played by the region 1540–1175 cm−1 and, to a lesser extent, the region 1700–1600 cm−1. The contribution of the phenolic fraction was identified as the main responsible for this observation. 相似文献
225.
Dr. Giuseppe Sciortino Dr. Daniele Sanna Dr. Giuseppe Lubinu Prof. Jean-Didier Maréchal Prof. Eugenio Garribba 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(49):11316-11326
Human serum albumin (HSA) is involved in the transport of metal ions and potential metallodrugs. Depending on the metal, several sites are available, among which are N-terminal (NTS) and multi-metal binding sites (MBS). Despite the large number of X-ray determinations for albumins, only one structure with Zn2+ is available. In this work, the binding to HSA of the VIVO2+ ion was studied by an integrated approach based on spectroscopic and computational methods, which allowed the systems to be characterized even in the absence of X-ray analysis. The behavior depends on the type of albumin, defatted (HSAd) or fatted (HSAf). With HSAd ‘primary’ and ‘secondary’ sites were revealed, NTS with (His3, His9, Asp13, Asp255) and MBS with (His67, His247, Asp249, Asn99 or H2O); with increasing the ratio VIVO2+/HSAd, ‘tertiary’ sites, with one His-N and other donors (Asp/Glu-O or carbonyl-O) are populated. With HSAf, fatty acids (FAs) cause a rotation of the subdomains IA and IIA, which results in the formation of a dinuclear ferromagnetic adduct (VIVO)2D(HSAf) with a μ1,1-Asp249 and the binding of His247, Glu100, Glu252, and His67 or Asn99. FAs hinder also the binding of VIVO2+ to the MBS. 相似文献
226.
Luca Nuvoli Davide Sanna Valeria Alzari Daniele Nuvoli Vanna Sanna Luca Malfatti Alberto Mariani 《Journal of polymer science. Part A, Polymer chemistry》2016,54(14):2166-2170
Frontal polymerization was successfully used to synthesize copolymer hydrogels of poly(N‐vinylcaprolactam‐co‐itaconic acid). All materials were characterized by response to stimuli (pH and/or temperature), depending on the itaconic acid content. Namely, relatively low amounts of this latter were found to be crucial for determining the degree of swelling. In particular, hydrogels behave differently if swollen at pH values that are higher or lower of 7–8, and exhibit temperature response as well (lower critical solution temperature at ca. 30 °C), which makes these materials potentially interesting for biomedical applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2166–2170 相似文献
227.
Angelo Zinellu Salvatore Sotgia Elisabetta Pisanu Bastianina Scanu Manuela Sanna Maria Franca Usai Roberto Chessa Luca Deiana Ciriaco Carru 《Analytical and bioanalytical chemistry》2010,398(5):1973-1978
The role of neurotransmitter amino acids (NAAs) in the functioning of the nervous system has been the focus of increasingly
intense research over the past several years. Among the various amino acids that have important roles as neurotransmitters,
there are alanine (Ala), glutamic acid (Glu), aspartic acid (Asp), serine (Ser), taurine (Tau) and glycine (Gly). NAAs are
present in plasma, cells and—at trace levels—in all biological fluids, but complex components in biological matrices make
it difficult to determine them in biological samples. We describe a new capillary electrophoresis (CE) method with laser-induced
fluorescence detection by which analytes are resolved in less than 12 minutes in a 18 mmol/L phosphate run buffer at pH 11.6.
The use of elevated temperatures during sample derivatization leads to a drastic reduction in the reaction time, down to 20 min,
compared to the 6–14 h usually described for reactions between FITC and amino acids at room temperature. In order to demonstrate
its wide range of applications, the method was applied to the analysis of NAA in human plasma and in other sample types, such
as red blood cells, urine, cultured cells, cerebrospinal fluid, saliva and vitreous humor, thus avoiding the typical limitations
of other methods, which are normally suitable for use with only one or two matrix types. 相似文献
228.
Angelo Zinellu Valeria Pasciu Salvatore Sotgia Bastianina Scanu Fiammetta Berlinguer Giovanni Leoni Sara Succu Ignazio Cossu Eraldo Sanna Passino Salvatore Naitana Luca Deiana Ciriaco Carru 《Analytical and bioanalytical chemistry》2010,398(5):2109-2116
We describe a new capillary electrophoresis laser-induced fluorescence (CE-LIF) method for the quantification of adenosine 5′-triphosphate (ATP) in spermatozoa and oocytes. The optimization of the precapillary derivatization reaction between ATP and 4,4-difluoro-5,7-dimethyl-4-bora-3a,4adiaza-s-indacene-3-propionyl ethylene diamine hydrochloride (BODIPY FL EDA) has been described. BODIPY-ATP conjugate was analysed in an uncoated fused silica capillary of 75 μm ID and 50 cm effective length using a 10 mmol/L tribasic sodium phosphate buffer, pH 11.5, at 22 kV in <5 min. A good reproducibility of intra- and inter-assay tests was obtained (CV?=?4.55% and 7.14%, respectively). With respect to our previous CE-UV assay, the new method showed an improvement in sensitivity that was about 120-fold (limit of quantification, 0.15 vs 18 μmol/L). Method applicability was proven on the reproductive cells of several animal species (roosters, horses, sheep and goats). Due to the elevated sensitivity, the new assay allows the measurement of adenosine 5′-triphosphate levels from just 20 oocytes. Considering that ATP concentration in reproductive cells is related to the mitochondrial integrity after cryopreservation, the proposed method could be a useful tool in assisted reproductive technologies. 相似文献
229.
230.
T. Grahn A. Dewald P. T. Greenlees U. Jakobsson J. Jolie P. Jones R. Julin S. Juutinen S. Ketelhut T. Kr?ll R. Krücken M. Leino P. Maierbeck B. Melon M. Nyman R. D. Page P. Peura Th. Pissulla P. Rahkila J. Sarén C. Scholey J. Sorri J. Uusitalo 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):291-294
The lifetime of the 17/2+ yrast state in 195Po has been measured using the recoil distance Doppler-shift technique to be = 43(11) ps. The lifetime was extracted from the singles -ray spectra obtained by using the recoil-decay tagging method. The present work provides more information of the coupling
schemes, shapes and configuration mixing in neutron-deficient odd-mass Po nuclei. 相似文献