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71.
The thermal reaction between nitrosoarenes and alkynes under alkylating conditions produces N-alkoxyindoles as the major products in moderate to good yields and excellent regioselectivity. Various electrophiles are used affording different NO-protected hydroxyindoles in a multi-component fashion. Privileged acetylenic substrates used in reactions with substituted nitrosoarenes are arylalkynes or propiolates. Potentially bioactive compounds and other classes of highly functionalizable indole products were prepared. Reactions between o-carbomethoxy-nitrosoarenes and arylacetylenes provided tricyclic compounds containing an acylaziridine indoline skeleton.  相似文献   
72.
The search for new sources of natural pigments has increased, mainly because of the toxic effects caused by synthetic dyes used in food, pharmaceutical, textile, and cosmetic industries. Fungi provide a readily available alternative source of natural pigments. In this context, the fungi Penicillium chrysogenum IFL1 and IFL2, Fusarium graminearum IFL3, Monascus purpureus NRRL 1992, and Penicillium vasconiae IFL4 were selected as pigments producers. The fungal identification was performed using ITS and part of the β-tubulin gene sequencing. Almost all fungi were able to grow and produce water-soluble pigments on agro-industrial residues, with the exception of P. vasconiae that produced pigments only on potato dextrose broth. The production of yellow pigments was predominant and the two strains of P. chrysogenum were the largest producers. In addition, the production of pigments and mycotoxins were evaluated in potato dextrose agar using TOF-MS and TOF-MS/MS. Metabolites as roquefortine C, chrysogine were found in both extracts of P. chrysogenum, as well fusarenone X, diacetoxyscirpenol, and neosolaniol in F. graminearum extract. In the M. purpureus extract, the pigments monascorubrin, rubropunctatin, and the mycotoxin citrinin were found. The crude filtrates have potential to be used in the textile industry; nevertheless, additional pigment purification is required for food and pharmaceutical applications.  相似文献   
73.
In this work electronic and optoelectronic properties of InGaN/GaN nanocolumn quantum disk LEDs have been studied with the multiscale simulation tool tiberCAD. Calculations have been performed with an atomistic tight-binding model. Results shows that emission energies have a minor dependence on the nanocolumn dimension while In concentration in the active region is a critical parameter.  相似文献   
74.
We study multi-fissuration and debonding phenomena of a thin film bonded to a stiff substrate using the variational approach to fracture mechanics. We consider a reduced one-dimensional membrane model where the loading is introduced through uniform inelastic (e.g., thermal) strains in the film or imposed displacements of the substrate. Fracture phenomena are accounted for by adopting a Griffith model for debonding and transverse fracture. On the basis of energy minimization arguments, we recover the key qualitative properties of the experimental evidences, like the periodicity of transverse cracks and the peripheral debonding of each regular segment. Phase diagrams relate the maximum number of transverse cracks that may be created before debonding takes place, as a function of the material properties and the sample’s geometry. The theoretical results are illustrated with numerical simulations obtained through a finite element discretization and a regularized variational formulation of the Ambrosio–Tortorelli type, which is suited to further extensions in two-dimensional settings.  相似文献   
75.
76.
Abstract

The development of new synthetic methods for the monoalkylation of calix[4]arenes at the lower rim allows the synthesis of a new class of trihydroxamate siderophores. Three chelating hydroxamic acid units are introduced through a sequence of reactions which blocks the macrocycle in the cone conformation. The new ligands obtained form neutral 1:1 complexes (FeL) with iron (III), which are stable in EtOH/H2O 9:1 at pH 2–7. Calix[4]arene bis-crown ethers are prepared by exploiting the selective 1,2-(proximal) functionalization of calix[4]arenes at the lower rim. These ligands are, however, less effective in complexing alkali metal cations compared with the 1,3-calix[4]arene crown-ethers which, in their partial cone structure, offer a better shielding for the complexed cations. Rigid upper rim-bridged calix[4]arenes potentially useful for the inclusion of neutral molecules are prepared by exploiting the selective 1,3-diformylation of calix[4]arene at the upper rim. Finally a new chloromethylation method for calix[4]arenes blocked in the cone conformation is described together with the synthesis of new cavitands.  相似文献   
77.
Fusarium langsethiae, formally described as a new species over a decade ago, has been identified as the main producer of HT‐2 (HT2) and T‐2 (T2) toxins in Europe in small cereal grains. Mycotoxin contamination caused by this Fusarium species can represent a food safety hazard that deserves further attention. In the present work, the mycotoxin profile in wheat cultures of F. langsethiae is presented with particular reference to the production of major type‐A trichothecenes and their glucosyl derivatives. F. langsethiae isolates, representative of the major Italian wheat cultivation areas, were tested for the production of T2, HT2, diacetoxyscirpenol (DAS) and neosolaniol (NEO), and relevant glucosyl derivatives. Liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) was used for the identification and chemical characterization of these metabolites. F. langsethiae isolates under investigation resulted to be potent producers of T2, HT2 and NEO. Furthermore, a well‐defined set of isolates, all originating from Central Italy, produced also DAS. All isolates were found to be able to produce HT2 glucosyl derivatives, whereas only traces of T2 glucoside were detected in one sample. Furthermore, two mono‐glucosyl derivatives of NEO and one mono‐glucoside derivative of DAS were identified and characterized. The screening for the presence/absence of glucosylated trichothecenes in analyzed fungal extracts revealed a general co‐occurrence of these derivatives with the parent toxin at levels that could be roughly estimated to account up to 37% of the relevant unconjugated toxin. This is the first report of the production of glucosylated trichothecenes by F. langsethiae cultured on small grains. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
78.
Novel drug delivery systems capable of continuous sustained release of therapeutics have been studied extensively for use in the prevention and management of chronic diseases. The use of these systems holds promise as a means to achieve higher patient compliance while improving therapeutic index and reducing systemic toxicity. In this work, an implantable nanochannel drug delivery system (nDS) is characterized and evaluated for the long-term sustained release of atorvastatin (ATS) and trans-resveratrol (t-RES), compounds with a proven role in managing atherogenic dyslipidemia and promoting cardioprotection. The primary mediators of drug release in the nDS are nanofluidic membranes with hundreds of thousands of nanochannels (up to 100,000/mm2) that attain zero-order release kinetics by exploiting nanoconfinement and molecule-to-surface interactions that dominate diffusive transport at the nanoscale. These membranes were characterized using gas flow analysis, acetone diffusion, and scanning and transmission electron microscopy (SEM, TEM). The surface properties of the dielectric materials lining the nanochannels, SiO2 and low-stress silicon nitride, were further investigated using surface charge analysis. Continuous, sustained in vitro release for both ATS and t-RES was established for durations exceeding 1 month. Finally, the influence of the membranes on cell viability was assessed using human microvascular endothelial cells. Morphology changes and adhesion to the surface were analyzed using SEM, while an MTT proliferation assay was used to determine the cell viability. The nanochannel delivery approach, here demonstrated in vitro, not only possesses all requirements for large-scale high-yield industrial fabrication, but also presents the key components for a rapid clinical translation as an implantable delivery system for the sustained administration of cardioprotectants.  相似文献   
79.
Abstract: The synthesis of the indolo[2,3-a]carbazole ring is described starting from 3-chloromethylene-1,3-dihydro-indol-2-one 5 and 3-(cyano-ethoxycarbonyl-methyl)-indole-1-carboxylic acid ethyl ester 4.  相似文献   
80.
A new program, PHI, with the ability to calculate the magnetic properties of large spin systems and complex orbitally degenerate systems, such as clusters of d‐block and f‐block ions, is presented. The program can intuitively fit experimental data from multiple sources, such as magnetic and spectroscopic data, simultaneously. PHI is extensively parallelized and can operate under the symmetric multiprocessing, single process multiple data, or GPU paradigms using a threaded, MPI or GPU model, respectively. For a given problem PHI is been shown to be almost 12 times faster than the well‐known program MAGPACK, limited only by available hardware. © 2013 Wiley Periodicals, Inc.  相似文献   
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