The reactions of
▪ with some primary and secondary aliphatic amines affording selective ring opening at C
β are reported. The reactions with secondary amines HNR
1R
2 (R
1
=
R
2
=
Et; R
1
=
Bu
t, R
2
...=
CH
2CH
2O(CO)C(CH
3)
CH
2; R
1
=
Et, R
2
=
CH
2CH
2OH; R
1
=
R
2
=
CH
2CH
2OH) gave the corresponding C
8F
17CH
2
CH(OH)
CH
2
NR
1R
2 derivatives. For R
1
=
Et, R
2
=
CH
2CH
2OH; R
1
=
R
2
=
CH
2CH
2OH, the reactions proceed through the selective nucleophilic attack of the NH moiety with no evidence of reactivity of the OH group. The reactions with the primary amines, allylamine and
n-hexamethylenediamine, gave different products depending on reaction conditions.
(Perfluoroalkyl)methyloxirane
▪ reacts with some primary and secondary aliphatic amines affording selective ring opening at C
β to form the corresponding amino alcohol derivatives.
▪
Anti-HEV antibodies were detected in animals from abattoir and in farms from northeast Brazil. Our results suggest that HEV is highly disseminated in the swine population and might present a great ...risk to animal handlers and for consumption of raw or undercooked meat and meat products in northeast Brazil.
Aflatoxins are fungal metabolites extensively produced by many different fungal species that may contaminate a wide range of agricultural food products. They have been studied extensively because of ...being associated with various chronic and acute diseases, especially immunosuppression and cancer, and their presence in food is strictly monitored and regulated worldwide.
Aflatoxin detection and measurement rely mainly on chemical methods usually based on chromatography approaches, and recently developed immunochemical based assays that have advantages but also limitations, since these are expensive and destructive techniques. Nondestructive, optical approaches are recently being developed to assess presence of contamination in a cost and time effective way, maintaining acceptable accuracy and reproducibility. In this paper are presented the results obtained with a simple portable device for nondestructive detection of aflatoxins in almonds. The presented approach is based on the analysis of fluorescence spectra of slurried almonds under 375 nm wavelength excitation. Experiments were conducted with almonds contaminated in the range of 2.7–320.2 ng/g total aflatoxins B (AFB1 + AFB2) as determined by High Performance Liquid Chromatography with Fluorescence Detection (HPLC/FLD). After applying pre-processing steps, spectral analysis was carried out using a binary classification model based on Support Vector Machine (SVM) algorithm. A majority vote procedure was then performed on the classification results. In this way we could achieve, as best result, a classification accuracy of 94% (and false negative rate 5%) with a threshold set at 6.4 ng/g. These results illustrate the feasibility of such approach in the great challenge of aflatoxin detection for food and feed safety.
•Fluorescence spectroscopy proves effective as a rapid and low cost approach to detect aflatoxin B.•Results are obtained using machine learning algorithms and a consensus strategy on single results.•Results have proved robust using data from different locations and instruments.
A first attempt to homologize male palpal bulb structures of theraphosine spiders is made, with the aim of providing systematic characters. The morphology and distribution of palpal bulb keels of ...over 60 species in 27 genera of Theraphosinae is presented and discussed. Four basic groups of keels were recognized and a terminology was created to name them: prolateral inferior and prolateral superior keels, for the two more or less parallel keels found on the prolateral bulb face; apical keel, for the ventral keel located just before the apex of the embolus; subapical keel, for a keel located just before the apical keel; and, retrolateral keel, for the keel located on the retrolateral region, originating on the apical region and extending backwards. Other palpal bulb keels, apart from these four basic groups, as well as other structures, were found in some genera and/or species, constituting apomorphies for these groups.
The reaction chemistry of nitriles, RCN, where R is usually an organyl group, with transition metal complexes is reviewed. The review surveys data published during the period 1977-early 1994 on new ...reaction processes such as insertion into metal-hydrogen and -carbon bonds, coupling between one nitrile and an unsaturated metal fragment or between two nitriles, reduction to amines, attack by protic and aprotic nucleophiles and electrophilic attack as well as some catalytic transformations, which result from the ability of nitriles to coordinate to transition metal centres with a consequent change in the electrophilicity or nucleophilicity of the coordinated ligand.
The cationic allyl complex
2 containing a pyridine-“click”-triazole chelator is an active catalyst for Suzuki–Miyaura coupling.
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► Synthesis of a novel palladium η
3-allyl cationic ...complex containing a “click” triazole based chelating ligand. ► X-ray structure determination of the above complex. ►
1H and
13C NMR, IR and MS(ESI) characterization. ► NMR study of the dynamic behavior of the complex in solution. ► Preliminary studies of its catalytic activity in Suzuki–Miyaura reaction.
The synthesis and characterization of the cationic complex Pd(η
3-C
3H
5)(2-((4-phenyl-1
H-1,2,3-triazol-1-yl)methyl)pyridine)(BF
4) (
2) are reported. The solid-state structure of
2 has been unambiguously confirmed by single-crystal X-ray diffraction analysis.
1H NMR spectroscopy reveals that in solution complex
2 is dynamic and that
syn–
syn,
anti–
anti exchange of the allyl protons occurs. Complex
2 exhibits good activity in the Suzuki–Miyaura coupling of aryl bromides with phenyl boronic acid.
The Infectious Bursal Disease Virus (IBDV) causes immunosuppression in young chickens. Advances in molecular virology and vaccines for IBDV have been achieved by viral reverse genetics (VRG). VRG for ...IBDV has undergone changes over time, however all strategies used to generate particles of IBDV involves multiple rounds of amplification and need of in vitro ligation and restriction sites. The aim of this research was to build the world's first VRG for IBDV by yeast-based homologous recombination; a more efficient, robust and simple process than cloning by in vitro ligation. The wild type IBDV (Wt-IBDV-Br) was isolated in Brazil and had its genome cloned in pJG-CMV-HDR vector by yeast-based homologous recombination. The clones were transfected into chicken embryo fibroblasts and the recovered virus (IC-IBDV-Br) showed genetic stability and similar phenotype to Wt-IBDV-Br, which were observed by nucleotide sequence, focus size/morphology and replication kinetics, respectively. Thus, IBDV reverse genetics by yeast-based homologous recombination provides tools to IBDV understanding and vaccines/viral vectors development.
Newly synthesized fluorescent nanoparticles of 2-amino-6-ethoxy-4-4-(4-morpholinyl)phenyl-3,5-pyridinedicarbonitrile have been developed and characterized for possible applications as security marker ...in paper documents. Nanoparticles have been prepared by reprecipitation in water under sonication. The size and the shape of these nanoparticles, characterized by light scattering and atomic force microscopy, have been found to be highly dependent on sonication power. Typical sizes range from tens to hundreds of nanometers. Furthermore, a remarkable increase in the fluorescence yield has been observed as nanoparticles sizes decrease. Finally, all of the above features, together with the striking stability of optical and mechanical properties over the course of months, allow for straightforward applications that rely on strong and stable fluorescence such as marking important or valuable documents.
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