Search results for "substrate"
showing 8 items of 1018 documents
The Hexameric Resorcinarene Capsule as a Brønsted Acid Catalyst for the Synthesis of Bis(heteroaryl)methanes in a Nanoconfined Space
2019
Herein, we show that the hexameric resorcinarene capsule C is able to catalyze the formation of bis(heteroaryl)methanes by reaction between pyrroles or indoles and carbonyl compounds (α-ketoesters or aldehydes) in excellent yields and selectivity. Our results suggest that the capsule can play a double catalytic role as a H-bond catalyst, for the initial activation of the carbonyl substrate, and as a Bronsted acid catalyst, for the dehydration of the intermediate alcohol.
<title>Electrochromism of W-oxide-based films: some theoretical and experimental results</title>
1995
We survey some recent work related to electrochromic W-oxide-based thin films. The electronic structure of cubic (perovskite) WO3 and HWO3 was calculated from first principles. It was found, among other things, that hydroxide formation was energetically favored. Experimental studies were made on films prepared by reactive magnetron sputtering in Ar + O2 with and without CF4 addition and substrate bias. Structural studies by atomic force microscopy, x-ray diffraction, infrared reflectance spectroscopy, and Raman spectroscopy indicated that the electron bombardment associated with a positive substrate bias led to grain growth and partial crystallization while maintaining a high density of W e…
SERS detection of cell surface and intracellular components of microorganisms using nano-aggregated Ag substrate
2016
Abstract The intracellular and cell surface composition and structural features of gram-positive and gram-negative bacteria were identified using near-infrared surface-enhanced Raman scattering (SERS). The structural differences of components that reside in the cell envelope are manifested by their SERS spectra, e.g. gram-negative vs. gram-positive. Silver particles were used as a SERS substrate by exploiting the existence of strong local electromagnetic fields (hot spots) within nanoscale aggregates of the particles. The aggregation of silver nanoparticles was induced by magnesium ions. These hot spots reduce the screening length of the double layer. The obtained SERS spectra showed excell…
From soil to soil-less in horticulture: quality and typicity
2013
In this review, the technique of soil-less cultivation of horticultural crops is analysed, the main differences between this and traditional cultivation techniques are described, and the advantages and disadvantages of each method in relation to the others are identified. Soilless cultivation has revolutionised various sectors of vegetable and floriculture production, and recent years have also seen interest being shown by Italian fruit crop producers, particularly those involved in table grape viticulture. The various issues related to the use of this technique are described in relation to the needs of the substrate, water management, and mineral nutrition of the different species, and to …
Biochemical and structural analysis of the NS5B RNA-dependent RNA polymerase of the hepatitis C virus.
2000
Hepatitis C virus (HCV), the major causative agent of chronic and sporadic non-A, non-B hepatitis worldwide, is a distinct member of the Flaviviridae virus family. These viruses have in common a plus-strand RNA genome that is replicated in the cytoplasm of the infected cell via minus-strand RNA intermediates. Owing to the lack of reliable cell culture systems and convenient animal models for HCV, the mechanisms governing RNA replication are not known. As a first step towards the development of appropriate in vitro systems, we expressed the NS5B RNA-dependent RNA polymerase (RdRp) in insect cells, purified the protein to near homogeneity and studied its biochemical properties. It is a primer…
Characterization of the autoantigen La (SS-B) as a dsRNA unwinding enzyme
1997
During the analysis of the La (SS-B) autoantigen for catalytic activities an ATP-dependent double-stranded RNA unwinding activity was detected. Both native and recombinant La proteins from different species displayed this activity, which could be inhibited by monospecific anti-La antibodies. La protein was able to melt dsRNA substrates with either two 3'-overhangs or a single 3'- and a 5'-overhang. Double-stranded RNAs with two 5'-overhangs were not unwound, indicating that at least one 3'-overhang is required for unwinding. Sequence elements of the La protein that might be involved in dsRNA unwinding, such as an evolutionarily conserved putative ATP-binding motif and an element that is hom…
Plant essential oils in controlling fungal colonization on wooden substrate
2021
In order to control fungal colonization and the related deterioration process of cultural objects, several chemical compounds are actually utilised. These products generally are toxic, not biodegradable and persisting for long time in the environment, also acting on not-targeted biological systems. In this study, specifically to wooden cultural object, Origanum vulgare L. and Thymus vulgaris L. essential oils are proposed as green biocides to contrast the development of Penicillium chrysogenum, Aspergillus flavus and Aspergillus niger fungal species. The aim is replacing toxic products with natural molecules, proposing alternative methodologies supporting the using of non-toxic novel compou…
α-Conotoxins EpI and AuIB switch subtype selectivity and activity in native versus recombinant nicotinic acetylcholine receptors
2003
The Xenopus laevis oocyte expression system was used to determine the activities of alpha-conotoxins EpI and the ribbon isomer of AuIB, on defined nicotinic acetylcholine receptors (nAChRs). In contrast to previous findings on intracardiac ganglion neurones, alpha-EpI showed no significant activity on oocyte-expressed alpha3beta4 and alpha3beta2 nAChRs but blocked the alpha7 nAChR with an IC50 value of 30 nM. A similar IC50 value (103 nM) was obtained on the alpha7/5HT3 chimeric receptor stably expressed in mammalian cells. Ribbon AuIB maintained its selectivity on oocyte-expressed alpha3beta4 receptors but unlike in native cells, where it was 10-fold more potent than native alpha-AuIB, had…