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951.
Francesco Fini Michela Beltrani Raffaella Mancuso Bartolo Gabriele Carla Carfagna 《Advanced Synthesis \u0026amp; Catalysis》2015,357(1):177-184
Aryl α‐diimine derivatives have been used, for the first time, as efficient new ligands for the palladium‐catalyzed oxidative bis‐alkoxycarbonylation reaction of olefins. The most active catalyst was formed in situ from bis(9‐anthryl)‐2,3‐dimethyl‐1,4‐diazabutadiene and palladium(II) trifluoroacetate [Pd(TFA)2]. This catalytic system was able to selectively convert olefins into succinic diesters in good yields (up to 97%) and low catalyst loading (up to 0.5 mol%) under mild reaction conditions [4 bar of carbon monoxide (CO) at 20 °C in the presence of p‐toluenesulphonic acid as additive and p‐benzoquinone as oxidant]. The optimized conditions could be successfully applied to both aromatic and aliphatic olefins, by using methanol, benzyl alcohol or isopropyl alcohol as nucleophiles.
952.
Francesco Ferella Ida De Michelis Agostino Scocchera Mario Pelino Francesco Vegliò 《中国化学工程学报》2015,(2)
The study is focused on the extraction of valuable metals from automotive shredder residue (ASR) by different leaching solutions. First, ASR samples were roasted at 600 °C to simulate a thermal treatme... 相似文献
953.
Roberto Cighetti Carlotta Ciaramelli Stefania Enza Sestito Dr. Ivan Zanoni Łukasz Kubik Dr. Ana Ardá‐Freire Dr. Valentina Calabrese Francesca Granucci Prof. Roman Jerala Prof. Sonsoles Martín‐Santamaría Prof. Jesus Jiménez‐Barbero Prof. Francesco Peri 《Chembiochem : a European journal of chemical biology》2014,15(2):250-258
Monosaccharide lipid A mimetics based on a glucosamine core linked to two fatty acid chains and bearing one or two phosphate groups have been synthesized. Compounds 1 and 2 , each with one phosphate group, were practically inactive in inhibiting LPS‐induced TLR4 signaling and cytokine production in HEK‐blue cells and murine macrophages, but compound 3 , with two phosphate groups, was found to be active in efficiently inhibiting TLR4 signal in both cell types. The direct interaction between compound 3 and the MD‐2 coreceptor was investigated by NMR spectroscopy and molecular modeling/docking analysis. This compound also interacts directly with the CD14 receptor, stimulating its internalization by endocytosis. Experiments on macrophages show that the effect on CD14 reinforces the activity on MD‐2 ? TLR4 because compound 3 's activity is higher when CD14 is important for TLR4 signaling (i.e., at low LPS concentration). The dual targeting of MD‐2 and CD14, accompanied by good solubility in water and lack of toxicity, suggests the use of monosaccharide 3 as a lead compound for the development of drugs directed against TLR4related syndromes. 相似文献
954.
Prof. Marcello Leopoldo Dr. Marialessandra Contino Prof. Francesco Berardi Prof. Roberto Perrone Prof. Nicola Antonio Colabufo 《ChemMedChem》2014,9(1):38-42
PET radiotracer development to target in vivo P‐glycoprotein (P‐gp) could be an important strategy for the early diagnosis of neurodegenerative disorders such as Alzheimer’s disease (AD). Indeed, as a dysfunction of P‐gp is responsible for the accumulation of β‐amyloid plaques (a hallmark of AD) in brain parenchyma, P‐gp is the cause of AD onset. P‐gp substrates and inhibitors are useful for imaging the activity or expression of this protein, respectively; herein we discuss the in vivo evaluation of some 11C radiotracers with P‐gp‐inhibitory activity, such as [11C]MC18 and [11C]MC113, as well as P‐gp substrates [11C]MC266 and [11C]MC80. Moreover, the radiosynthesis of all these P‐gp probes is reported. 相似文献
955.
Novel hybrid materials composed by a high density polyethylene (HDPE) matrix and powdered rubber coming from scrap tyres (ground tyre rubber [GTR]) were prepared. Two methods were followed: ethylene was polymerized by a metallocene catalyst (Cp2ZrCl2/methylaluminoxane) in the presence of a toluene dispersion of the filler (in‐situ polymerization); and the ethylene was polymerized out after supporting the aluminum‐based co‐catalyst onto the rubber particles surface (polymerization filling technique). The experimental conditions were varied in order to achieve the best catalyst productivity. All the synthesized composites were characterized in order to investigate the occurrence and the extent of interactions between HDPE macromolecular chains and the GTR components and their effects onto the final properties, by comparison with a composite where GTR was included into the matrix through blending in the melt. Scanning electron microscopy, atomic force microscopy, and solvent extractions were performed to this aim. The amount of thermoplastic matrix bonded to the filler was determined, and the extracted polymer was characterized by size exclusion chromatography and differential scanning calorimetry. Finally, stress–strain behavior of the composites obtained, respectively, by catalytic polymerization and melt mixing was compared. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40313. 相似文献
956.
Gian Piero Celata Francesco D’Annibale Andrea Mariani Salvatore Sau Emanuele Serra Roberto Bubbico Carla Menale Heiko Poth 《Chemical Engineering Research and Design》2014
The results of an experimental study on the effects of the flow of nanofluids (water-based suspensions of nanometer-sized solid particles) on metal surfaces are presented. Either different nanofluids (containing TiO2, Al2O3, ZrO2, and SiC, respectively) and different target materials (aluminum, copper, stainless steel) have been investigated, under similar operating conditions. Different behaviors were observed depending on the specific combination nanofluid-target material, which in some cases led to severe damaging of the tested target, thus highlighting the need for an adequate preliminary investigation of the possible interactions between the selected nanofluid and the apparatus materials, before its adoption as heat transfer fluid. 相似文献
957.
Spadoni M Voltaggio M Carcea M Coni E Raggi A Cubadda F 《The Science of the total environment》2007,376(1-3):160-177
Biogeochemical mapping of selenium in Italian agricultural soils was accomplished by measuring the Se concentration of representative samples of wheat grains from 71 provinces. The range of the concentration values averaged on a provincial basis was 7-245 ng Se g(-1). A multiple regression model based on six geochemical and pedoclimatic variables was developed to interpret the observed data and to predict Se concentration of wheat in areas where analytical data were missing and in the different Italian soil regions. The statistical model explained only part of the observed variance, but succeeded in identifying Se-enriched as well as Se-depleted areas with an acceptable level of agreement with the biogeochemical map based on measured Se in wheat. Furthermore, the model showed that within the range of concentrations measured in Italian soils, Se-bioaccessibility is controlled not only by the Se content of the soil parent rocks, but also by their overall geochemical nature (carbonatic vs. silicatic) and by pedoclimatic variables (temperature and rain intensity excursions) related to fluctuations of soil moisture and pH. Overall, several Se-marginal and Se-deficient areas were identified on the Italian territory. The implications of these findings for public health are discussed briefly. 相似文献
958.
Influence of Feeding and Oviposition by Phytophagous Pentatomids on Photosynthesis of Herbaceous Plants 总被引:1,自引:0,他引:1
Violeta Velikova Gianandrea Salerno Francesca Frati Ezio Peri Eric Conti Stefano Colazza Francesco Loreto 《Journal of chemical ecology》2010,36(6):629-641
Feeding by herbivorous insects may change photosynthetic activity of host plants. We studied how feeding and oviposition by
herbivorous stink bugs, Murgantia histrionica and Nezara viridula (Heteroptera: Pentatomidae), affect photosynthetic parameters of Brassica oleracea (savoy cabbage) and Phaseolus vulgaris (French bean). First, we measured photosynthetic gas exchange, chlorophyll fluorescence imaging, and emission of induced
volatile organic compounds (VOC) immediately after feeding and during a post-feeding period. Photosynthesis decreased rapidly
and substantially in B. oleracea and P. vulgaris infested by feeding bugs. Stomatal conductance did not decrease proportionally with photosynthesis; instead, inhibition of
photosynthesis likely was due to a reduced diffusion of CO2 in the mesophyll. We also measured the impact of oviposition per se and oviposition associated with feeding on photosynthetic parameters. A surprisingly large inhibition of photosynthesis was
detected in cabbage leaves in response to oviposition by M. histrionica, even when oviposition was not associated with feeding activity. High resolution chlorophyll fluorescence imaging revealed
that the damage to photochemistry caused by feeding and oviposition was restricted to the attacked areas. By contrast, the
photochemical yield increased temporarily in the unaffected areas of the attacked leaves, indicating the onset of a compensatory
response. Measurement of volatile organic compounds (VOC) revealed that feeding-damaged plants did not emit detectable amounts
of VOC, indicating cellular damage (methanol and green leaf volatiles). However, feeding by M. histrionica induced emission of mono- and sesquiterpenes in savoy cabbage leaves. The different time-course of the induction of these
two classes of terpenes may reflect the induction of two different biosynthetic pathways and indicate different roles of these
terpenoids in tritrophic interactions. 相似文献
959.
We discuss an interpretation of the mixture transition distribution (MTD) for discrete‐valued time series which is based on a sequence of independent latent variables which are occasion‐specific. We show that, by assuming that this latent process follows a first order Markov Chain, MTD can be generalized in a sensible way. A class of models results which also includes the hidden Markov model (HMM). For these models we outline an EM algorithm for the maximum likelihood estimation which exploits recursions developed within the HMM literature. As an illustration, we provide an example based on the analysis of stock market data referred to different American countries. 相似文献
960.
A new analytical method for evaluation of elastic stresses and deformations in axisymmetric plates having variable thickness according to a power of a linear function, either solid or annular, subjected to symmetrical bending due to lateral loads either distributed on upper surface or distributed along the inner or the outer edges. The proposed procedure is based on two independent integrals of the hypergeometric differential equation describing the rotation field and constitutes the generalization of the one found in the literature. This method allows to study a wide range of plates, be they solid or annular, converging or diverging with linear or non-linear thickness function, convex, concave or linear tapered, without the restrictions of the known procedures. Analytical results obtained by using this method utterly match both theoretical results which may be obtained in the specific case known (constant-thickness circular plate, linear variable thickness annular circular plate) and numerical results obtained by using FEA. 相似文献