197,290 research outputs found
Isolation and phytotoxicity of Apocarotenoids from Chenopodium album
No full textTwo new compounds (1, 2) and 16 apocarotenoids (3−18) were isolated from the weed Chenopodium album. The structures of new apocarotenoids were determined to be (3R,6R,7E,9E,11E)-3-hydroxy-13-apo-α-caroten-13-one (1) and (6S,7E,9E,11E)-3-oxo-13-apo-α-caroten-13-one (2) by spectroscopic, NMR, and MS analysis. Five of the known compounds (5, 6, 13, 15, and 17) were previously reported only as synthetic compounds. Effects of these compounds on germination and growth of Lactuca sativa (lettuce) were studied in the 10-4−10-7 M concentration rang
High temperature phase relations and topological constraints in the quaternary system MgO-Al2O3-SiO2-Cr2O3 : an experimental study
No full textPhase relationships in the system MgO-Al2O3-SiO2-Cr2O3 (MASCr) were investigated experi- mentally from 1250 to 1560 °C using a 1-atm vertical quench furnace on 12 oxide mixtures covering a wide range of chemical compositions. Spinel, corundum, mullite, and sapphirine were found to display a wide range of solid solutions toward CR-rich end-members, whereas enstatite, cordierite, forsterite, and glasses were always Cr-poor. Glasses formed in relatively MgO-rich bulk compositions from 1250 °C, in assemblage with cordierite, enstatite, forsterite, and spinel, suggesting a lowering of the eutectic minimum in MASCr compared to available melting relationships in the model system MAS. Although unexpected, the relatively low-temperature melting of Cr-bearing mixtures is sup- ported by topological constraints in the subsystems SACr and MSCr. The extent of Cr solubility in mullite has been found to reach ~14 wt% at 1560 °C, and 33 wt% in sapphirine at 1340 °C, which are the highest Cr values reported so far for these minerals. Liquidus surfaces are constrained by glass compositions that are displaced systematically toward silica compared to corresponding liquids in the ternary system MAS. As a consequence, the primary crystallization fields of Cr-spinel, Cr-sapphirine, and Cr-mullite are found to face the cristobalite/tridymite primary fields. A tentative liquidus diagram for the system MgO-Al2O3-SiO2-Cr2O3 is proposed, which could serve as a basis for the interpreta- tion of the high-temperature evolution of planetary materials as well as for the development of new ceramic materials
Lo stravaso da farmaco vescicante : una revisione narrativa = Vesicant drug extravasation . A narrative review
No full textIntroduzione Lo stravaso da farmaco vescicante rappresenta dallo 0,5% al 6% di tutti gli eventi avversi associati al trattamento. L’infermiere può assumere un ruolo chiave nel contribuire a ridurre la frequenza e la gravità di questo evento. L’obiettivo dello studio è quello di illustrare le più recenti raccomandazioni di buona pratica clinica in merito alla prevenzione e gestione dello stravaso da farmaco vescicante.
Materiali e metodi E’ stata condotta una revisione della letteratura attraverso banche dati biomediche e siti Internet istituzionali.
Risultati I fattori di rischio dipendono dal paziente, dalla procedura e dall’agente farmacologico. Il monitoraggio del sito, del paziente e dell’infusione è la chiave per prevenire lo stravaso. La gestione dello stravaso è non farmacologica e/o farmacologica o chirurgica nei casi più gravi. Sono indispensabili un processo di segnalazione spontanea degli eventi avversi (incident reporting) e un adeguato follow-up dopo il trattamento dello stravaso. Mancano prove di efficacia a supporto di una gestione standardizzata dello stravaso e sono inconcludenti quelle sull’uso di antidoti.
Conclusioni La prevenzione più efficace è un’adeguata formazione del personale infermieristico e informazione del paziente.Introduction Extravasation by vesicant is from 0.5% to 6.0% of all adverse events associated with treatment. Nurses can play a key role in helping to reduce the frequency and severity of this event. The objective of the study is to describe the most recent recommendations of good clinical practice for the prevention and the management of vesicant drug extravasation.
Methods A review of the literature through biomedical databases and institutional Internet sites was carried out.
Results Risk factors depend on patient, procedure and pharmacological agent. Monitoring the site, the patient and the infusion is the key to preventing the extravasation. The management of extravasation is non-pharmacological and/or pharmacological or surgical in severe cases. The incident reporting and an adequate follow-up after extravasation treatment are essential. There is a lack of evidence in support of a standardized management of extravasation and inconclusive evidence about the use of antidotes.
Conclusions The most effective prevention is an adequate training of nurse and patient information
Effect of proline analogues on the conformation of elastin peptides
No full textThree elastin model peptides containing the repetitive motif –VGVXGVG–, where X corresponds to
(2S)-proline (Pro), (2S,4R)-4-hydroxy-proline (Hyp) and (2S,4R)-4-methoxy-proline (Mop), were synthesized
in order to define the effect of the introduction of an electronegative group on the conformation and
self-assembling properties of the peptides. Circular dichroism, NMR and FT-IR spectroscopies evidenced
outstanding differences at molecular and supramolecular level. This work constitutes the basis for the
proper design of elastin-inspired drugs with tailored conformational properties
Chenoalbicin, a novel cinnamic acid amide alkaloid from chenopodium album
No full textThe roots of Chenopodium album were infused in MeOH, and the extract was partitioned between AcOEt and H2O. AcOEt-Soluble material was subjected to different silica-gel column chromatographies and then purified by reverse-phase HPLC to afford a new cinnamic acid amide alkaloid as a racemic mixture. The new compound, named chenoalbicin (1), was characterized by extensive spectroscopic investigation, especially 1D and 2D NMR spectroscopy. Its effects on the germination and growth of Lactuca sativa L. has been studied. The results are reported as percentage differences of germination, root elongation, and shoot elongation from the control at concentrations ranging from 10-4 to 10-7 M. © 2004 Verlag Helvetica Chimica Acta AG, Zürich
Design of a silicon transition radiation detector (SITRD) for accelerators and space applications
No full textCharacterization of a naturally inspired material engineered from elastin for tissue engineering applications.
No full textThe systems PbO-Al2O3-SiO2 (PAS) and MgO-Al2O3-SiO2 extended to PbO and Cr2O3 (PMASCr) at 1 Atm : investigations on phase relations and possible applications to the material sciences
No full textA proposal of robust regression for random fuzzy sets
No full textIn standard regression the Least Squares approach may fail to give valid estimates due to the presence of anomalous observations violating the method assumptions. A solution to this problem consists in considering robust variants of the parameter estimates, such as M-, S- and MM-estimators. In this paper, we deal with robustness in the field of regression analysis for imprecise information managed in terms of fuzzy sets. Although several proposals for regression analysis of fuzzy sets can be found in the literature, limited attention has been paid to the management of possible outliers in order to avoid inadequate results. After discussing the concept of outliers for fuzzy sets, a robust regression method is introduced on the basis of one of the proposals available in the literature. The robust regression method is applied to a synthetic data set and a comparison with the non-robust counterpart is given
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