A field deployable method for a rapid screening analysis of inorganic arsenic in seaweed

Inorganic arsenic (iAs) in 13 store-bought edible seaweed samples and 34 dried kelp (Laminaria digitata) samples was determined by a newly developed, field-deployable method (FDM) with the aid of a field test kit for arsenic in water. Results from the FDM were compared to results from speciation analysis achieved by using high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The FDM consisted of a simple extraction method using diluted HNO₃ to quantitatively extract iAs without decomposing the organoarsenicals to iAs followed by the selective volatilisation of iAs as arsine (AsH₃) and subsequent chemo-trapping on a filter paper soaked in mercury bromide (HgBr₂) solution. Method optimization with a sub-set of samples showed 80–94% iAs recovery with the FDM with no matrix effect from organo-arsenic species in the form of dimethylarsinic acid (DMA) on the iAs concentration. The method displayed good reproducibility with an average error of ±19% and validation by HPLC-ICP-MS showed that the results from the FDM were comparable (slope = 1.03, R² = 0.70) to those from speciation analysis with no bias. The FDM can be conducted within an hour and the observed limit of quantification was around 0.05 mg kg^?1 (dry weight). This method is well suited for on-site monitoring of iAs in seaweed before it is harvested and can thus be recommended for use as a screening method for iAs in seaweed.

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Graphical abstract Screening seaweed for their inorganic arsenic concentration within one hour without bias has been made possible in the field by using a field deployable arsenic kit. Its accuracy and precision was compared to HPLC-ICPMS.

     

Crystalline Pr:SrAl12O19 waveguide laser in the visible spectral region

We fabricated waveguides in Pr:SrAl(12)O(19) crystals by direct femtosecond laser writing. The propagation losses were calculated to be as low as 0.16 dB/cm at a wavelength of 633 nm. Laser oscillation in a diode-pumped waveguide at a wavelength of 643.5 nm was realized. The output power of the waveguide laser was 28.1 mW at a slope efficiency of 8%.     

Confirmation of drug delivery after liver chemoembolization: direct tissue doxorubicin measurement by UHPLC‐MS‐MS

Because liver cancer is rarely suitable for surgery, transcatheter arterial chemoembolization (TACE) is used for palliative therapy. In this procedure, an emulsion of doxorubicin in iodized oil is injected directly into liver tumors through a catheter positioned within the artery supplying blood flow to the tumor. At present, there is limited understanding of factors affecting the delivery and dispersion of doxorubicin within treated tumors during TACE. This study addresses the development and application of an ultrahigh‐pressure liquid chromatography–tandem mass spectrometry (UHPLC‐MS‐MS) method for rapid confirmation of drug delivery after TACE in a rabbit VX2 liver cancer model. Doxorubicin levels in liver tumors were measured using UHPLC‐MS‐MS and compared with computed tomography measured levels of iodized oil, a metric used clinically to indicate drug delivery. We found that tissue drug levels determined using UHPLC‐MS‐MS did not correlate with the regional iodized oil concentration (vehicle) within tumors following TACE, suggesting that chemotherapeutic drugs like doxorubicin spread throughout tumors, and that lack of iodized oil staining in portions of a tumor does not necessarily indicate inadequate therapy during TACE. Copyright © 2012 John Wiley & Sons, Ltd.     

FTIR spectroscopic investigation of oxygen spillover especially through the gas-phase. A reaction interesting in coke burning

Oxygen spillover through the gas phase was investigated, using FTIR spectroscopy to measure the reaction kinetics of the oxidation of benzoic acid, adsorbed to γ-alumina, in the absence and presence of a neighboring Pt grid. It could be shown that oxygen, activated on Pt may increase the oxidation rate, though there is no contact between Pt and the benzoic acid.     

Thermal and environmental stability of poly(4-ethynyl-p-xylylene-co-p-xylylene) thin films

The aim of this paper was to test the thermal and environmental stability of poly(4-ethynyl-p-xylyleneco-p-xylylene) thin films prepared by chemical vapor deposition(CVD) and to optimize the reaction conditions of the polymer.Fourier transformed infrared spectroscopy(FTIR),thermogravimetric analysis(TGA) and fluorescence microscopy were employed to investigate the stability of the reactive polymer coatings in various environmental conditions.Chemical reactivity of the thin films were then tested by Huisgen 1,3-dipolar cycloaddition reaction(‘‘click' reaction).The alkyne functional groups on poly(4-ethynyl-p-xylylene-co-p-xylylene) thin films were found to be stable under ambient storage conditions and thermally stable up to 100 8C when annealed at 0.08 Torr in argon.We also optimized the click reaction conditions of azide-functionalized molecules with poly(4-ethynyl-p-xylylene-co-p-xylylene).The best reaction result was achieved,when copper concentration was 0.5 mmol/L,sodium ascorbate concentration to copper concentration was 5:1.In contrast,the azide concentration and temperature had no obvious effect on the surface reaction.     

Bifurcations and subharmonic resonances in multi-degree-of-freedom panel models

This paper describes the nonlinear, postcritical behavior of parametrically excited, shallow, cylindrical panels, which are modeled with two or four degrees of freedom. The analysis shows complicated dynamic behavior. Stable, periodic motions coexist with the trivial solution for very small values of the excitation amplitude. Moreover, a stable, chaotic attractor could be found coexisting with the trivial solution.

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Sommario Si studia il comportamento postcritico nonlineare di pannelli cilindrici ribassati, soggetti ad eccitazione parametrica e modellati con due o quattro gradi di libertà. L'analisi evidenzia un comportamento dinamico complesso. Moti periodici stabili coesistono con la soluzione banale per valori molto piccoli dell'ampiezza dell'eccitazione. Un attrattore caotico stabile coesiste altresì con tale soluzione per alcuni valori della frequenza dell'eccitazione.

     

Thiadiazoloquinoxalines: tuning physical properties through smart synthesis

The synthesis of π-conjugated acceptors based on thiadiazoloquinoxaline (TQ) derivatives is described. Apart from reporting on the functionalization of the TQ core, the influence of the substituents was studied by UV-vis absorption and emission spectroscopy, cyclic voltammetry measurements, and DFT calculations. By changing the donor as well as the π-spacer, a fine-tuning of the photo- and electrochemical properties was achieved.