Determination of pharmaceuticals of various therapeutic classes by solid-phase extraction and liquid chromatography-tandem mass spectrometry analysis in hospital effluent wastewaters

A multi-residue analytical method has been developed and validated for determining a selection of 16 pharmaceuticals: the anti-epileptic carbamazepine, seven analgesic/anti-inflammatory drugs (mefenamic acid, indomethacine, ibuprofen, naproxen, diclofenac, ketorolac and acetaminophen), the analgesic opiate codeine, two antidepressants (fluoxetine and paroxetine), beta-blockers (atenolol and propranolol), antibiotic (trimethoprim, metronidazole, and erythromycin) and the anti-ulcer ranitidine in hospital effluent wastewaters. The method allows simultaneous extraction of the pharmaceuticals compounds by solid-phase extraction (SPE) using the Waters Oasis HLB at pH 7. The analytes were then identified and quantitatively determined by liquid chromatography-tandem mass spectrometry (LC-MS-MS) using multiple reaction monitoring (MRM). Recoveries of the pharmaceuticals were higher than 75%, with the exception of ranitidine (45%) and the overall variability of the method was below 9%. The instrumental detection limit (IDL) varied between 2 and 31 pg injected, the method detection limit (LOD) was between 7 and 47 ng/L in spiked hospital effluent. The precision of the method, calculated as relative standard deviation (RSD), ranged from 0.3 to 4.9%. A detail study off matrix effect is included in this work, regarding to signal suppression in these effluent wastewaters from a hospital complex samples. The developed analytical method was applied for preliminary data results in effluent wastewaters from a hospital.     

The geometric Neumann problem for the Liouville equation

Let Ω denote the upper half-plane ${\mathbb{R}_+^2}$ or the upper half-disk ${D_{\varepsilon}^+\subset \mathbb{R}_+^2}$ of center 0 and radius ${\varepsilon}$ . In this paper we classify the solutions ${v\in\;C^2(\overline{\Omega}\setminus\{0\})}$ to the Neumann problem $$\left\{\begin{array}{lll}{\Delta v+2 Ke^v=0\quad {\rm in}\,\Omega\subseteq \mathbb{R}^2_+=\{(s, t)\in \mathbb{R}^2: t >0 \},}\\ {\frac{\partial v}{\partial t}=c_1e^{v/2}\quad\quad\quad{\rm on}\,\partial\Omega\cap\{s >0 \},}\\ {\frac{\partial v}{\partial t}=c_2e^{v/2}\quad\quad\quad{\rm on}\,\partial\Omega\cap\{s <0 \},}\end{array}\right.$$ where ${K, c_1, c_2 \in \mathbb{R}}$ , with the finite energy condition ${\int_{\Omega} e^v < \infty}$ As a result, we classify the conformal Riemannian metrics of constant curvature and finite area on a half-plane that have a finite number of boundary singularities, not assumed a priori to be conical, and constant geodesic curvature along each boundary arc.     

Temperature dependence of grain growth in zone-refined tin containing large additions of zinc in solid solution

Grain growth in zone-refined tin containing high concentrations > 0.05 < 0.40 wt% Zn in solid solution have been investigated in the temperature range 70–160°C. It has been found that increasing the zinc content by a factor of 8 decreased the rate of grain growth by ∼ 30% at all annealing temperatures, and this was attributed to small variations of grain boundary mobility. In addition, the increase of annealing temperature from 70 to 160°C resulted in the increase of grain growth by a factor of ∼ 50 at any given concentration, which shows that the rate of grain growth is not strongly influenced by increasing the zinc concentration. The energy activating the growth process was calculated for all concentrations investigated and had a nearly constant value of ∼ 1 eV. An empirical formula was proposed relating the rate of grain growth and the solute concentration.     

PEG‐Biscyanoacrylate Crosslinker for Octyl Cyanoacrylate Bioadhesive

PEG400 (polyethylene glycol, M_W 400) biscyanoacrylate is synthesized and copolymerized with 2‐octyl cyanoacrylate for potential use as bioadhesive. PEG400 biscyanoacrylate is synthesized from the esterification of anthracenyl cyanoacrylic acid where the anthracene unit serves as vinyl‐protecting group. Copolymerization increases the plasticity, mechanical strength, and resilience of the resulted polymer as determined by dynamic mechanical analysis. Peeling test confirms its superior bioadhesive properties. Surface morphology is characterized by SEM imaging. The formulations are cytocompatible and safe. This cyanoacrylate composition may provide improved bioadhesive cyanoacrylates.

     

Phonon confinement effects in Raman spectra of porous silicon at non‐resonant excitation condition

Light emitting porous silicon samples with different porosities, i.e. crystalline sizes, were produced from the low level doped p‐type silicon wafers by the anodization process. The effects of strong phonon confinement, redshift and broadening, were found on the O(Γ) phonon mode of the Raman spectra recorded at non‐resonant excitation condition using a near infrared 1064 nm laser excitation wavelength. Similarly, the blueshift of the photoluminescence peak was observed by reducing the crystalline sizes. Vibrational and optical findings were analysed within the existing models of confinement on the vibrational and electronic states of silicon nanocrystals. Since the energy of the photoluminescence peak of small nanocrystals also depends on the oxygen content on the surface of nanocrystals, the surface oxidation states were examined using infrared and energy dispersive spectroscopy. The partial coverage of the surface of nanocrystals was found due to the sample exposure to air. As a consequence, the photoluminescence energy did not increase as would be expected from the quantum confinement model. These results further indicate that the oxygen passivation along with the quantum confinement determines the electronic states of the silicon nanocrystals in porous silicon. Copyright © 2014 John Wiley & Sons, Ltd.