Solid-phase extraction of triazole fungicides from water samples using disks impregnated with carbon nanotubes followed by GC-MS analysis

Triazole fungicides are pesticides widely employed in the cultivation of fruits, vegetables and grains. However, their ability to change the steroid hormone biosynthesis may result in endocrine complications for mammals, as well as changes in cholesterol and triglyceride levels and hepatotoxicity. The analysis of the triazole fungicides in superficial waters is important in order to monitor the risk for the biota. However, the use of efficient extraction procedures has been necessary in order to concentrate these pesticides before the analysis. In-disk solid-phase extraction (SPE) can be highlighted as a potential pre-concentration technique, mainly because the possibility to extract the analytes from a large sample volume, increasing the method detectability. Carbon nanotubes (CNTs) have been often used as solid extraction phase due to their high sorption capacity, surface area and internal volume, as well as mechanical, chemical and thermal stability. In this paper, we proposed the preparation of a new SPE disk impregnated with CNTs for the extraction of triazole fungicides from environmental water samples. The disks were obtained by acid corrosion of a cellulose membrane followed by its impregnation with CNTs. The developed method was validated for the analysis of triadimenol, tebuconazole and epoxiconazole, according to international validation protocols. The limits of quantification obtained for triadimenol, tebuconazole and epoxiconazole were 0.1, 0.1 and 0.05 µg L^?1, respectively. The linearity ranged from 0.05 to 10.00 µg L^?1 for epoxiconazole and from 0.1 to 10.00 µg L^?1 for triadimenol and tebuconazole, with correlation coefficients higher than 0.999 for all of them. The precisions, expressed as relative standard deviation, were lower than 12%. The accuracies were within ?12.07% to 17.7% (expressed as relative error).     

Heartwood of Dalbergia cochinchinensis: 4,7,2′-Trihydroxy-4′-methoxyisoflavanol and 6,4′-Dihydroxy-7-methoxyflavane Reduce Cytokine and Chemokine Expression In Vitro

Dalbergia cochinchinensis has been widely used in traditional medicine because of its flavonoids; however, the impact of the flavonoids to modulate the inflammatory response to oral cells remains to be described. For this aim, we isolated 4,7,2′-trihydroxy-4′-methoxyisoflavanol (472T4MIF) and 6,4′-dihydroxy-7-methoxyflavane (64D7MF) from the heartwood of D. cochinchinensis and confirmed the chemical structure by nuclear magnetic resonance. We show here that both flavonoids are inhibitors of an inflammatory response of murine RAW 264.7 inflammatory macrophages stimulated by LPS. This is indicated by interleukin (IL)1, IL6, and chemokine CCL2 production besides the phosphorylation of p65. Consistently, in primary murine macrophages, both flavonoids decreased the inflammatory response by lowering LPS-induced IL1 and IL6 expression. To introduce oral cells, we have used human gingival fibroblasts and provoked the inflammatory response by exposing them to IL1β and TNFα. Under these conditions, 472T4MIF, but not 64D7MF, reduced the expression of chemokines CXCL1 and CXCL2. Taken together, we identified two flavonoids that can reduce the expression of cytokines and chemokines in macrophages and fibroblastic cells.     

The effect of process variables on the characteristics of carbon nanotubes obtained by spray pyrolysis

A simple spray pyrolysis setup is used to grow multi-walled carbon nanotubes (MWCNTs), from a ferrocene solution in benzene as precursor. The effects of process variables such as growth temperature, position of the aerosol generator and position in the reactor where the sample was formed were investigated. These variables have a strong influence on the graphitization degree, homogeneity, diameter and alignment of the nanotubes, as observed by TEM, SEM, XRD and Raman spectroscopy. Vertically aligned MWCNT arrays with high density were obtained in large areas (10 × 10 mm²), with high yield (2.1 mg cm⁻²) and at a growth rate at 1.43 μm min⁻¹, by a suitable choice of the experimental conditions.     

A review of Bayesian dynamic forecasting models: Applications in marketing

We briefly review the main developments of Bayesian dynamic models. The emphasis is on marketing applications. Typical examples in this area are discussed. The concepts of monitoring and intervention are carefully explained with illustrative examples and open source computational routines. We avoid algebraic developments and instead use graphical examples to illustrate theoretical aspects. Two real-world problems using Bayesian dynamic models are discussed. Finally, we describe recent developments and alternative proposals to formally address the dependence when dealing with the modeling of multiple time series.     

Phenolic chemical composition of Petroselinum crispum extract and its effect on haemostasis

From the aqueous extract (Pc) of Petroselinum crispum (Mill) flat leaves specimens were isolated and identified the flavonoids apigenin (1), apigenin-7-O-glucoside or cosmosiin (2), apigenin-7-O-apiosyl-(1 --> 2)-O-glucoside or apiin (3) and the coumarin 2",3"-dihydroxyfuranocoumarin or oxypeucedanin hydrate (4). The inhibitory activity toward clotting formation and platelet aggregation was assessed for Pc flavonoids (1) and (2), and the coumarin (4). Pc showed no inhibition on clotting activity when compared with the control. On the other hand, a strong antiplatelet aggregation activity was observed for Pc (IC50 = 1.81 mg/mL), apigenin (IC50 = 0.036 mg/mL) and cosmosiin (IC50 = 0.18 mg/mL). In all cases ADP was used as inductor of platelet aggregation. Our results showed that Pc, apigenin and cosmosiin interfere on haemostasis inhibiting platelet aggregation. To the best of our knowledge this is the first report for the cosmosiin antiplatelet aggregation in vitro activity.     

Yttrium-86 Is a Positron Emitting Surrogate of Gadolinium for Noninvasive Quantification of Whole-Body Distribution of Gadolinium-Based Contrast Agents

Gadolinium-based contrast agents (GBCAs) are used to provide diagnostic information in clinical magnetic resonance (MR) examinations. Gadolinium (Gd) has been detected in the brain, bone and skin of patients, months and years following GBCA administration, raising concerns about long term toxicity. Despite increased scrutiny, the concentration, chemical form and fate of the retained gadolinium species remain unknown. Importantly, the whole body biodistribution and organ clearance of GBCAs is poorly understood in humans. Gadolinium lacks suitable isotopes for nuclear imaging. We demonstrate that the yttrium-86 isotope can be used as a gadolinium surrogate. We show that Gd and their analogous Y complexes have similar properties both in solution and in vivo, and that yttrium-86 PET can be used to track the biodistribution of GBCAs over a two-day period.     

Point Spectrum and SULE for Time-Periodic Perturbations of Discrete 1D Schrödinger Operators with Electric Fields

We use the KAM technique to present a proof of pure point spectrum for the quasi-energy operator and a version of the SULE condition for suitable small time-periodic perturbations of discrete one-dimensional Schrödinger operators with uniform electric fields.     

Carbon nanotube/dendrimer hybrids as electrodes for supercapacitors

Journal of Solid State Electrochemistry - Carbon nanotubes (CNTs) were surface-modified by a glycodendrimer with four glucose units (4-Gl). Electrodes for supercapacitors based on CNT/4-Gl hybrids...     

Incorporation, oxidation and pyrolysis of ferrocene into porous silica glass: a route to different silica/carbon and silica/iron oxide nanocomposites

This work reports the incorporation of ferrocene into a porous silica glass under ambient temperature and atmosphere. After or during the ferrocene incorporation, the spontaneous formation of ferricinium ions was observed by electron paramagnetic resonance (EPR), UV-visible, X-ray absorption near-edge structure (XANES), and 57Fe M?ssbauer measurements. It was shown that the oxidation of ferrocene molecules to ferricinium ions was promoted by air and that the Si-O- groups on the surface of the pores act as counteranions. Pyrolysis of the porous glass/ferricinium material under argon atmosphere and variable temperature yields different glass/carbon nanocomposites, which were subsequently treated with an HF solution in order to remove the glassy fraction. The resulting insoluble carbon materials were characterized by transmission electron microscopy (TEM), Raman, and EPR spectroscopy and consisted of amorphous carbon when the pyrolysis was carried out at 900 or 1000 degrees C and of a mixture of carbon nanotubes and carbonaceous materials at a pyrolysis temperature of 1100 degrees C. When the pyrolysis was conducted under air, the incorporated ferricinium forms alpha-Fe2O3, and the resulting material is a transparent and highly homogeneous glass/iron oxide nanocomposite.