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101.
Alessandra Bernardi 《Journal of Pure and Applied Algebra》2008,212(6):1542-1559
The ideal of a Segre variety Pn1×?×Pnt?P(n1+1)?(nt+1)−1 is generated by the 2-minors of a generic hypermatrix of indeterminates (see [H.T. Hà, Box-shaped matrices and the defining ideal of certain blowup surface, J. Pure Appl. Algebra 167 (2-3) (2002) 203-224. MR1874542 (2002h:13020)] and [R. Grone, Decomposable tensors as a quadratic variety, Proc. Amer. Math. 43 (2) (1977) 227-230. MR0472853 (57 #12542)]). We extend this result to the case of Segre-Veronese varieties. The main tool is the concept of “weak generic hypermatrix” which allows us to treat also the case of projection of Veronese surfaces from a set of general points and of Veronese varieties from a Cohen-Macaulay subvariety of codimension 2. 相似文献
102.
103.
Maria Alessandra Ragusa 《Journal of Global Optimization》2008,40(1-3):361-368
In this note we prove a sufficient condition for commutators of fractional integral operators to belong to Vanishing Morrey
spaces VL
p,λ. In doing this we use an extension on Morrey spaces of an inequality by Fefferman and Stein concerning the sharp maximal
function and the fractional maximal function and related Morrey inequalities.
相似文献
104.
de Souza Cabrini F. da Cunha Alessandra L. M. C. Auclio Ricardo Queiroz 《Chromatographia》2009,70(9-10):1461-1466
Micellar electrokinetic capillary chromatography was used for the determination of picoxystrobin and pyraclostrobin. The background electrolyte consisted of borate buffer (40 mmol L−1 pH 8.5), SDS (30 mmol L−1) and acetonitrile (15% in volume). Runs were made at 25 °C with 25 kV applied potential. The developed method was applied to analyte fortified urine samples. On-line analyte concentration, combined with a capillary of a longer optical path length, allowed limits of quantification of 8.6 × 10−8 mol L−1 for picoxystrobin and 1.8 × 10−7 mol L−1 for pyraclostrobin.
相似文献105.
Alam Gustavo Trov Silene Alessandra Santos Melo Raquel Fernandes Pupo Nogueira 《Journal of photochemistry and photobiology. A, Chemistry》2008,198(2-3):215-220
Photodegradation of the pharmaceuticals amoxicillin (AMX), bezafibrate (BZF) and paracetamol (PCT) in aqueous solutions via the photo-Fenton process was investigated under black-light and solar irradiation. The influences of iron source, initial H2O2 concentration and matrix (distilled water and sewage treatment plant effluent) on degradation efficiency were discussed in detail. The results showed that (i) the degradation of the drugs was favored in the presence of potassium ferrioxalate (FeOx) in comparison to Fe(NO3)3; (ii) the increase of the H2O2 concentration improved the efficiency of AMX and BZF oxidation; however, the same was not observed for PCT; (iii) the influence of the matrix was observed for the degradation of BZF and PCT; (iv) under solar irradiation, the oxidation of the BZF and PCT is faster than under black-light irradiation. All these pharmaceuticals can be efficiently degraded employing the process evaluated. 相似文献
106.
Maria Rubega Emanuela Formaggio Franco Molteni Eleonora Guanziroli Roberto Di Marco Claudio Baracchini Mario Ermani Nick S. Ward Stefano Masiero Alessandra Del Felice 《Entropy (Basel, Switzerland)》2021,23(5)
Stroke is the commonest cause of disability. Novel treatments require an improved understanding of the underlying mechanisms of recovery. Fractal approaches have demonstrated that a single metric can describe the complexity of seemingly random fluctuations of physiological signals. We hypothesize that fractal algorithms applied to electroencephalographic (EEG) signals may track brain impairment after stroke. Sixteen stroke survivors were studied in the hyperacute (<48 h) and in the acute phase (∼1 week after stroke), and 35 stroke survivors during the early subacute phase (from 8 days to 32 days and after ∼2 months after stroke): We compared resting-state EEG fractal changes using fractal measures (i.e., Higuchi Index, Tortuosity) with 11 healthy controls. Both Higuchi index and Tortuosity values were significantly lower after a stroke throughout the acute and early subacute stage compared to healthy subjects, reflecting a brain activity which is significantly less complex. These indices may be promising metrics to track behavioral changes in the very early stage after stroke. Our findings might contribute to the neurorehabilitation quest in identifying reliable biomarkers for a better tailoring of rehabilitation pathways. 相似文献
107.
Cristina Airoldi Dr. Silvia Sommaruga Dr. Silvia Merlo Paola Sperandeo Dr. Laura Cipolla Prof. Alessandra Polissi Prof. Francesco Nicotra Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(6):1897-1902
Lipopolysaccharide (LPS) is an essential component of the outer membrane of Gram‐negative bacteria and consists of three elements: lipid A, the core oligosaccharide, and the O‐antigen. The inner‐core region is highly conserved and contains at least one residue of 3‐deoxy‐D ‐manno‐octulosonate (Kdo). Arabinose‐5‐phosphate isomerase (API) is an aldo–keto isomerase catalyzing the reversible isomerization of D ‐ribulose‐5‐phosphate (Ru5P) to D ‐arabinose‐5‐phosphate (A5P), the first step of Kdo biosynthesis. By exploiting saturation transfer difference (STD) NMR spectroscopy, the structural requirements necessary for API substrate recognition and binding were identified, with the aim of designing new API inhibitors. In addition, simple experimental conditions for the STD experiments to perform a fast, robust, and efficient screening of small libraries of potential API inhibitors, allowing the identification of new potential leads, were set up. Due to the essential role of API enzymes in LPS biosynthesis and Gram‐negative bacteria survival, by exploiting these data, a new generation of potent antibacterial drugs could be developed. 相似文献
108.
Massimo Bietti Alessandra Calcagni Daniel Oscar Cicero Roberto Martella Michela Salamone 《Tetrahedron letters》2010,51(31):4129-1537
A product study on the reactivity of a 1,1-diarylalkoxyl radical bearing 2,2-diphenylcyclopropyl groups in the para-positions has been carried out. The exclusive formation of a product deriving from cyclopropyl ring-opening has been observed, indicating that 1,1-diarylalkoxyl radicals exist in equilibrium with a bridged 1-oxaspiro[2,5]octadienyl radical. This represents the first experimental evidence in support of the stepwise nature of the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. 相似文献
109.
Annemarie Huijser Dr. Alessandro Pezzella Dr. Jonas K. Hannestad Lucia Panzella Dr. Alessandra Napolitano Prof. Marco d'Ischia Prof. Villy Sundström Prof. 《Chemphyschem》2010,11(11):2424-2431
The UV‐dissipative mechanisms of the eumelanin building block 5,6‐dihydroxyindole‐2‐carboxylic acid (DHICA) and the 4,7‐dideutero derivative (DHICA‐d2) in buffered H2O or D2O have been characterized by using ultrafast time‐resolved fluorescence spectroscopy. Excitation of the carboxylate anion form, the dominating state at neutral pH, leads to dual fluorescence. The band peaking at λ=378 nm is caused by emission from the excited initial geometry. The second band around λ=450 nm is owed to a complex formed between the mono‐anion and specific buffer components. In the absence of complex formation, the mono‐anion solely decays non‐radiatively or by emission with a lifetime of about 2.1 ns. Excitation of the neutral carboxylic acid state, which dominates at acidic pH, leads to a weak emission around λ=427 nm with a short lifetime of 240 ps. This emission originates from the zwitterionic state, formed upon excitation of the neutral state by sub‐ps excited‐state intramolecular proton transfer (ESIPT) between the carboxylic acid group and the indole nitrogen. Future studies will unravel whether this also occurs in larger building blocks and ESIPT is a built‐in photoprotective mechanism in epidermal eumelanin. 相似文献
110.
Qasim Chaudhry Nadège Piclin Jane Cotterill Marco Pintore Nick R Price Jacques R Chrétien Alessandra Roncaglioni 《Chemistry Central journal》2010,4(Z1):S5