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The voltammetric characterisation and determination of insecticide flonicamid (N-cyanomethyl-4-(trifluoromethyl)nicotinamide) were performed for the first time using a simple electrochemical sensor, renewable silver-amalgam film electrode (Hg(Ag)FE). During the development of the direct cathodic square wave voltammetric method (SWV) for the determination of flonicamid, a voltammetric behaviour of a target analyte in aqueous Britton-Robinson buffer solution from pH 2.0 to pH 11.98 was examined. In the investigated pH range, the peak which appeared in the potential span between −0.86 V and −1.56 V vs. saturated calomel electrode depending on the applied pH value was chosen for analytical purposes. As optimal pH for the determination of flonicamid, pH 2.5 was selected. Cyclic voltammetric measurements at pH 2.5 confirmed that the electrode reaction mechanism is an irreversible reduction controlled by the diffusion of flonicamid at Hg(Ag)FE. The optimised Hg(Ag)FE-SWV method resulted in good linearity in the concentration range of 1.96–41.2 µg mL−1 while the relative standard deviation of the method was 0.30%. Flonicamid was successfully determined in commercial formulation Teppeki 500 WG® and spiked river water sample by the developed method using the standard addition procedure. The average value of flonicamid amount found in a commercial formulation based on three repetitions was 497.8 ± 0.9 g kg−1, which is in good agreement with the manufacturer's declaration (500 ± 25 g kg−1) and with comparative high-performance liquid chromatographic measurements with diode array detection where a found average value of flonicamid content was 497.5 ± 11.5 g kg−1. The obtained results also indicate that the developed SWV procedure using Hg(Ag)FE was appropriate for the determination of flonicamid in a spiked river water sample with the recovery of 92.86% and RSD of 6.19%. [ABSTRACT FROM AUTHOR]

Sonochemistry in combination with a combustion procedure was used to prepare superparamagnetic iron oxide nanoparticles. Two different iron precursors, ferrocene and iron(II)-acetate were dispersed in polyethylene-glycol (PEG) with different molecular weight (200–1000) by using a high efficiency ultrasonic technique. The sonochemical treatment initiated the precipitation of iron-hydroxide particles, then the PEG based colloids were burnt to create the iron oxide nanoparticles. Three phases were observed in the samples, magnetite (Fe3O4), hematite (α-Fe2O3), and maghemite (γ-Fe2O3) and their ratio can be modified by changing the iron precursor and the type of PEG. Elektrokinetic (Zeta) potential and the particle size of the synthesized iron oxide nanoparticle samples were measured and the one (A1) based on iron(II)-acetate and PEG200 have been selected to test in DNA purification, because it has negative and small size distribution. The synthesized superparamagnetic nanoparticles have been used successfully in biological isolation (DNA, deoxyribonucleic acid purification), and thus, the developed synthetic procedure is more than suitable for such applications. Sonochemical-combustion method was used to synthesize superparamagnetic nanoparticles. Magnetite, hematite and maghemite nanoparticles were synthesized. The ratio of the iron oxide phases can be tuned by changing the precursors. High molecular weight PEG promote the formation of maghemite and hematite. High molecular weight PEG inhibits the formation of magnetite. The prepared nanoparticles are applicable for DNA purification. [ABSTRACT FROM AUTHOR]

It has been generally accepted for long that water molecules are integral parts of layered double hydroxides (LDHs). It is even thought that in the absence of water molecules, there is no LDH structure. It is shown in this contribution that via the solvolysis of Mg- or Ca-alkoxides and Al-alkoxide with methanol or propanol and co-precipitated in methanolic methoxide, water-free LDH-like structures could be constructed. These novel LDH-like materials proved to be more active and selective catalysts in a Knoevenagel condensation than the corresponding 'classical' LDHs. Synthesis, thought to be not possible to prepare, characterization and a catalytic application of water-free LDHs are described. Water molecules are replaced by small alcohol molecules in the interlayer space. [ABSTRACT FROM AUTHOR]

Several ellagitannins inhibited the activity of protein phosphatase-1 (PP1) and -2 A (PP2A) catalytic subunits (PP1c and PP2Ac) with preferential suppression of PP1c over PP2Ac. The inhibitory potency for PP1c followed the order of tellimagrandin I > mahtabin A > praecoxin B > 1.2-Di-O-galloyl-4.6-(S)-HHDP-β-D-glucopyranose > pedunculagin with IC50 values ranging from 0.20 µM to 2.47 µM. The interaction of PP1c and tellimagrandin I was assessed by NMR saturation transfer difference, surface plasmon resonance, isothermal titration calorimetry, and microscale thermophoresis based binding techniques. Tellimagrandin I suppressed viability and phosphatase activity of HeLa cells, while mahtabin A was without effect. Conversely, mahtabin A increased the phosphorylation level of SNAP-25Thr138 and suppressed exocytosis of cortical synaptosomes, whereas tellimagrandin I was without influence. Our results establish ellagitannins as partially selective inhibitors of PP1 and indicate that these polyphenols may act distinctly in cellular systems depending on their membrane permeability and/or their actions on cell membranes. [ABSTRACT FROM AUTHOR]

Effect of sonication time on the synthesis of the CdS nanoparticles within the matrix obtained through the covalent functionalization of multiwall carbon nanotube (MWCNT) with maleic anhydride (MA) - 1-octene copolymer was investigated. Cadmium chloride and thiourea were used as the raw materials. MWCNTs used for the matrix were synthesized by Catalytic Chemical Vapor Deposition using Fe-Co/Al2O3 as the catalyst. The obtained nanostructures were characterized by FTIR, XRD, Raman spectroscopy, TEM, SEM, TG and UV-Vis spectroscopy. Electrophysical properties of the polymer nanocomposites obtained using different periods of time for sonication were comparably investigated. The average CdS particle diameter was between 3.9-7.9 nm as confirmed independently by TEM and XRD. UV-Vis spectroscopy revealed that the obtained nanostructures are appropriate base materials for making optical devices. [ABSTRACT FROM AUTHOR]

Graphene-like nanostructures were synthesized from multiwall carbon nanotubes through chemical exfoliation route in mild conditions. For this purpose multiwall carbon nanotubes were synthesized by Chemical Vapor Deposition method using Al-Fe-Co catalyst and treated with KMnO4. The obtained nanostructures were characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM and TEM methods. FTIR results show that, treating the carbon nanotubes with KMnO4decorates their surface with oxygen containing functional groups. XRD and Raman spectroscopy results reveal that the outermost layers of the nanotubes were exfoliated during the treatment. The formation of graphene-like nanostructures was confirmed by SEM and TEM methods. The novelty of this work is the first time use of this type of mild and cheap condition for obtaining graphene-like nanostructures from MWCNTs without any other intermediate treatment. [ABSTRACT FROM PUBLISHER]

Context and objective: Lead (Pb) is a heavy metal harmful for human health and environment. From leaded gasoline (still used in certain countries), and in Pb processing and reprocessing industries, airborne particles are emitted which can be inhaled. In such exposure, the size of particles entering the airways is crucial. The nervous system is a primary target for Pb, and consequences like occupational neuropathy and delayed mental development of children are well-known. The aim of this work was to investigate the neurotoxicity of Pb nanoparticles (NPs) applied into the airways of rats. Methods: Nano-sized lead oxide particles (mean diameter ca. 20 nm) were suspended in distilled water and instilled into the trachea of adult male Wistar rats (in doses equivalent to 2 and 4 mg/kg Pb), 5 times a week for 3 and 6 weeks. At the end, open field motility was tested, then central and peripheral nervous activity was recorded in urethane anesthesia. Results and conclusion: The treated rats'' body weight gain was significantly lower than that of the controls from the 3rd week onwards, and the weight of their lungs was significantly increased. Horizontal motility increased while vertical motility decreased. Spontaneous cortical activity was shifted to higher frequencies. The somatosensory cortical evoked potential showed increased latency and decreased frequency-following ability, and similar alterations were seen in the tail nerve. Significant Pb deposition was measured in blood, brain, lung and liver samples of the treated rats. The experiments performed seem to constitute an adequate model of the human effects of inhaled Pb NPs. [ABSTRACT FROM AUTHOR]

The toxicity of manganese-containing airborne particles is an important occupational and environmental problem. In this work, adult male Wistar rats were treated with a nanosuspension of MnO2 of approximately 23 nm nominal particle diameter, instilled into the trachea for 3, 6, and 9 wk in doses of 2.63 and 5.26 mg Mn/kg. The animals’ body weight was checked weekly. At the end of treatment, the rats’ spontaneous motility was tested in an open field box. Then, spontaneous and stimulus-evoked cortical activity and action potential of the tail nerve were recorded in urethane anesthesia. The rats were finally dissected, organs weights were measured, and the presence of excess Mn in lung and brain samples was determined using scanning electron microscopy with energy-dispersive x-ray spectroscopy. While control rats had normal weight gain, the body weights of the treated rats ceased to grow from wk 6 on. The relative weight of the lungs increased in the treated rats, and that of the liver decreased, in a dose- and time-dependent manner; Mn was detected in their lung and brain samples. In the open field activity, the percentage of ambulation and rearing decreased while local activity and immobility increased. The latency of the evoked potentials was lengthened, and the conduction velocity of the tail nerve decreased. These results indicate that the Mn content of instilled nanoparticles had access from the airways to the brain, and the resulting damage could be investigated in animals using neuro-functional and general toxicological endpoints. [ABSTRACT FROM AUTHOR]