121,784 research outputs found
Thermoplastic compositions based on non-polar organic polymers and zeolites in acid form,which have strong adhesion to metals and composite objects obtainable therefrom
No full textA thermoplastic composition based on non-polar organic polymers and crystalline zeolites in acid form of which the exchangeable ions are totally or partly substituted by H+ ions, the composition having strong adhesion to metals, the invention also relating to composite objects obtainable therefrom
Systems Training for Emotional Predictability and Problem Solving (STEPPS): program Efficacy and Personality Features as Predictors of Drop-out-An Italian study
No full textThermodynamic and Kinetic Stabilities of Al(III) Complexes with N2O3 Pentadentate Ligands
No full text: Al(III) complexes have been recently investigated for their potential use in imaging with positron emission tomography (PET) by formation of ternary complexes with the radioisotope fluorine-18 (18F). Although the derivatives of 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) are the most applied chelators for [Al18F]2+ labelling and (pre)clinical PET imaging, non-macrocyclic, semi-rigid pentadentate chelators having two N- and three O-donor atoms such as RESCA1 and AMPDA-HB have been proposed with the aim to allow room temperature labelling of temperature-sensitive biomolecules. The paucity of stability data on Al(III) complexes used for PET imaging instigated a complete thermodynamic and kinetic solution study on Al(III) complexes with aminomethylpiperidine (AMP) derivatives AMPTA and AMPDA-HB and the comparison with a RESCA1-like chelator CD3A-Bn (trans-1,2-diaminocyclohexane-N-benzyl-N,N',N'-triacetic acid). The stability constant of [Al(AMPDA-HB)] is about four orders of magnitude higher than that of [Al(AMPTA)] and [Al(CD3A-Bn)], highlighting the greater affinity of phenolates with respect to acetate O-donors. On the other hand, the kinetic inertness of the complexes, determined by following the Cu2+-mediated transmetallation reactions in the 7.5-10.5 pH range, resulted in a spontaneous and hydroxide-assisted dissociation slightly faster for [Al(AMPTA)] than for the other two complexes (t1/2 = 4.5 h for [Al(AMPTA)], 12.4 h for [Al(AMPDA-HB)], and 24.1 h for [Al(CD3A-Bn)] at pH 7.4 and 25 °C). Finally, the [AlF]2+ ternary complexes were prepared and their stability in reconstituted human serum was determined by 19F NMR experiments
NDF degradability of hays measured in situ and in vitro
No full textThe NDF degradability (d(NDF)) of hays measured by an in situ method (nylon bag technique) was compared with in vitro fermentation, using the Daisy(II) incubator (Ankom(R), Tech. Co., Fairport, NY, USA). Eighteen hays were produced from mountain areas (about 700 m.s.l.) from plots subjected to different cutting frequencies (two to four cuts per season) and types of N fertilisation (slurry and slurry plus mineral). Hay samples from each cut were incubated (in situ) in the rumens of three cows (incubation times: 2, 4, 8, 16, 24, 48 and 72 h; sample weight: 15 mg/cm(2) of free bag area) or inserted (in vitro) into three different digestion jars Oar volume: 2 1; bag size 5 cm x 3 cm; sample weight: 250 mg per bag) that were placed into the Daisy(11) incubator for 48 h.
The forages showed large variation in effective d(NDF) (assumed rumen turn over rate: 3% per hour) which ranged from 38 to 43% for hays with two cuts to 58-65% for the hays with four cuts per season. The d(NDF) obtained in situ (Y, effective) and in vitro (X, after 48 h of incubation) were highly correlated (P < 0.01) and the regression equation was
Y = 0.74(+/-0.05)X + 6.39(+/-2.90), n = 18, S.D. = +/-1.96, r(2) = 0.94.
The variability (coefficient of variation, CV) of the in vitro measurements (among jar repeatability) was 2.8%, which is close to that generally found for some chemical analyses of feedstuffs and lower than that obtained for the in situ measures (among cow repeatability, CV: 3.7%). The Daisy(II) incubator produces repeatable in vitro d(NDF) data which are highly related to those obtainable with the reference in situ procedure. (C) 2003 Elsevier Science B.V. All rights reserved
Underlining the Importance of Peripheral Protic Functional Groups to Enhance the Proton Exchange of Gd-Based MRI Contrast Agents
No full textIn this study, we report the synthesis and the equilibrium, kinetic, relaxation, and structural properties of two new GdIII complexes based on modified 10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (HPDO3A) designed to modulate the relaxivity at acidic and basic pH due to intra- and intermolecular proton exchange. The presence of a carboxylic or ester moieties in place of the methyl group of HPDO3A allowed differentiation of a protic and nonprotic functional group, highlighting the importance of the formation of an intramolecular hydrogen bond between the coordinated hydroxyl and the carboxylate groups for proton exchange (kH = 1.5 × 1011 M-1 s-1, kOH = 1.7 × 109 M-1 s-1). The determination of the thermodynamic stability and kinetic inertness of the GdIII complexes confirmed that the modification of peripheral groups does not significantly affect the coordination environment and thus the stability (log KGdL = 19.26, t1/2 = 2.14 × 107 hours, pH = 7.4, 0.15 M NaCl, 25 °C). The relaxivity (r1) was measured as a function of pH to investigate the proton exchange kinetics, and as a function of the magnetic field strength to extrapolate the relaxometric parameters (r1GdL1 = 4.7 mM-1 s-1 and r1GdL2 = 5.1 mM-1 s-1 at 20 MHz, 25 °C, and pH 7.4). Finally, the X-ray crystal structure of the complex crystallized at basic pH showed the formation of a tetranuclear dimer with alkoxide and hydroxide groups bridging the GdIII ions
Carbohydrate-based synthetic ion transporters
No full textIn this work, carbohydrate-based systems designed as artificial ion transporters have been surveyed.
Despite the large structural diversity and ease of manipulations of carbohydrates, in principle endowed
with a variety of desirable properties for ionophoric activity, only few examples of sugar-containing
compounds have been reported in the literature for these purposes. The most remarkable example is
the family of modified b-cyclodextrins, resulting in active cation and/or anion transporters when long,
flexible n-alkyl or oligo-ethylene or butylene glycol chains are appended at the lower rim of the macrocycle.
Interesting features have been also found in amphiphilic CyPLOS (Cyclic Phosphate-Linked
Oligosaccharide) dimers, that is macrocycles with two phenyl-b-D-glucopyranoside residues, 4,6-linked
through phosphodiester bonds, derivatized with tetraethylene glycol tentacles. A wider repertoire of
available carbohydrate-based scaffolds is expected to largely stimulate the discovery of novel, efficient
artificial ionophores, of great interest for both technological and biomedical applications
Prevalence of Frailty and Mobility Limitation in a Rural Setting in France
No full textBACKGROUND:
The prevalence of frailty is variable according to the adopted operational definition, the tested population, and the setting where it is explored.
OBJECTIVE:
To estimate the prevalence of frailty and mobility disability in community-dwelling persons aged 60 years and older.
DESIGN:
Cross-sectional analyses.
SETTING:
The rural area of Labastide-Murat (France).
PARTICIPANTS:
All community-dwelling persons aged 60 years and older living in the area and answering to the study survey (n=572/1022).
MEASUREMENTS:
The study questionnaire included questions defining mobility disability (as ability to walk 400 meters and climb up 2 flights of stairs) and frailty (according to the FRAIL instrument and a modified version of the original definition proposed by Fried and colleagues).
RESULTS:
Mean age of participants was 72.4 years old. Mobility disability was reported by 47 (8.3%) participants. The sedentariness criterion of frailty was the most prevalent in the present population. Overall, according to the FRAIL instrument, 77.6%, 14.0%, and 8.3% could be defined as robust, pre-frail/frail, and disabled, respectively. When the alternative definition of frailty mirroring the definition proposed in the Cardiovascular Health Study was adopted, the prevalence of frailty increased and showed gender-specific differences (p=0.02).
CONCLUSIONS:
A relevant number of older persons living in rural areas experiences physical impairments and presents an increased risk for major negative health-related events. These results may support the ongoing clinical and research actions aimed at preventing the functional decline in elders
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Carbohydrate-based synthetic ion transporters
No full textIn this work, carbohydrate-based systems designed as artificial ion transporters have been surveyed. Despite the large structural diversity and ease of manipulations of carbohydrates, in principle endowed with a variety of desirable properties for ionophoric activity, only few examples of sugar-containing compounds have been reported in the literature for these purposes. The most remarkable example is the family of modified β-cyclodextrins, resulting in active cation and/or anion transporters when long, flexible n-alkyl or oligo-ethylene or butylene glycol chains are appended at the lower rim of the macrocycle. Interesting features have been also found in amphiphilic CyPLOS (Cyclic Phosphate-Linked Oligosaccharide) dimers, that is macrocycles with two phenyl-β-d-glucopyranoside residues, 4,6-linked through phosphodiester bonds, derivatized with tetraethylene glycol tentacles. A wider repertoire of available carbohydrate-based scaffolds is expected to largely stimulate the discovery of novel, efficient artificial ionophores, of great interest for both technological and biomedical applications
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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