Dual purpose laser ablation-inductively coupled plasma mass spectrometry for pulsed laser deposition and diagnostics of thin film fabrication: Preliminary study

PLD (pulsed laser deposition) is an attractive technique to fabricate thin films with a stoichiometry reflecting that of the target material. Conventional PLD instruments are more or less black boxes in which PLD is performed virtually “blind”, i.e. without having great control on the important PLD parameters. In this preliminary study, for the first time, a 213 nm Nd-YAG commercial laser ablation-inductively coupled plasma mass spectrometer (LA-ICPMS) intended for microanalysis work was used for PLD under atmospheric pressure and in and ex situ ICPMS analysis for diagnostics of the thin film fabrication process.A PLD demonstration experiment in a He atmosphere was performed with a Sm_13.8Fe_82.2Ta_4.0 target-Ta-coated silicon wafer substrate (contraption with defined geometry in the laser ablation chamber) to transfer the permanent magnetic properties of the target to the film. Although this paper is not dealing with the magnetic properties of the film, elemental analysis was applied as a means of depicting the PLD process. It was shown that in situ ICPMS monitoring of the ablation plume as a function of the laser fluence, beam diameter and repetition rate may be used to ensure the absence of large particles (normally having a stoichiometry somewhat different from the target). Furthermore, ex situ microanalysis of the deposited particles on the substrate, using the LA-ICPMS as an elemental mapping tool, allowed for the investigation of PLD parameters critical in the fabrication of a thin film with appropriate density, homogeneity and stoichiometry.     

Synthesis,Bioactivity, Pharmacokinetic and Biomimetic Properties of Multi-Substituted Coumarin Derivatives

A series of novel multi-substituted coumarin derivatives were synthesized, spectroscopically characterized, and evaluated for their antioxidant activity, soybean lipoxygenase (LOX) inhibitory ability, their influence on cell viability in immortalized human keratinocytes (HaCaT), and cytotoxicity in adenocarcinomic human alveolar basal epithelial cells (A549) and human melanoma (A375) cells, in vitro. Coumarin analogues 4a–4f, bearing a hydroxyl group at position 5 of the coumarin scaffold and halogen substituents at the 3-phenyl ring, were the most promising ABTS^•+ scavengers. 6,8-Dibromo-3-(4-hydroxyphenyl)-4-methyl-chromen-2-one (4k) and 6-bromo-3-(4,5-diacetyloxyphenyl)-4-methyl-chromen-2-one (3m) exhibited significant lipid peroxidation inhibitory activity (IC₅₀ 36.9 and 37.1 μM). In the DCF-DA assay, the 4′-fluoro-substituted compound 3f (100%), and the 6-bromo substituted compounds 3i (80.9%) and 4i (100%) presented the highest activity. The 3′-fluoro-substituted coumarins 3e and 4e, along with 3-(4-acetyloxyphenyl)-6,8-dibromo-4-methyl-chromen-2-one (3k), were the most potent lipoxygenase (LOX) inhibitors (IC₅₀ 11.4, 4.1, and 8.7 μM, respectively) while displaying remarkable hydroxyl radical scavenging ability, 85.2%, 100%, and 92.9%, respectively. In silico docking studies of compounds 4e and 3k, revealed that they present allosteric interactions with the enzyme. The majority of the analogues (100 μΜ) did not affect the cell viability of HaCaT cells, though several compounds presented over 60% cytotoxicity in A549 or A375 cells. Finally, the human oral absorption (%HOA) and plasma protein binding (%PPB) properties of the synthesized coumarins were also estimated using biomimetic chromatography, and all compounds presented high %HOA (>99%) and %PPB (60–97%) values.     

Nonlinear optical properties of ferrocene- and porphyrin-[60]fullerene dyads.

A series of novel [60]fullerene-ferrocene and [60]fullerene-porphyrin dyads, in which a fullerene and an electron donating moiety are attached through a flexible triethylene glycol linker are synthesized and their nonlinear optical (NLO) response studied. Specifically, the third-order susceptibility chi(3) of all fullerene derivatives are measured in toluene solutions by the optical Kerr effect (OKE) technique using 532 nm, 35 ps laser pulses and their second hyperpolarizability gamma are determined. All fullerene dyads studied exhibit enhancement of their NLO response compared to pristine fullerenes which has been attributed to the formation of a charge separated state. All experimentally measured hyperpolarizability gamma values are also calculated by the semiempirical methods AM1 and PM3. A good correlation is found between the theoretical and experimental values, suggesting that simple semiempirical methods can be employed for the designing and optimization of the fullerene-containing dyads displaying improved nonlinear responses.     

A convenient synthesis of 3-aryl-4H- Benzopyrano[3,4-d]isoxazol-4-ones

Regioselective 1,3-dipolar cycloaddition of nitrile oxides 5a-c to ethyl o-hydroxycinnamate (3) gave the corresponding ethyl trans-3-aryl-4,5-dihydro-5-(2-hydroxyphenyl)-4-isoxazolecarboxylates 6a-c . Their structure was confirmed by reductive cleavage to 1 and compounds 9a-c . Compounds 6a-c afforded upon heating in the presence of pyridine the 3-aryl-4H-[1]benzopyrano[3,4-d]isoxazol-4-ones 11a-c . Compound 10c was also isolated from 6c and transformed thermally into 11c .     

Spherical spectral synthesis and two-radius theorems on Damek–Ricci spaces

We prove that spherical spectral analysis and synthesis hold in Damek–Ricci spaces and derive two-radius theorems.     

Guest Editorial: The Professional Status of European Chemists and Chemical Engineers

Which country pays its chemists and chemical engineers the highest salaries? Where can I find a new job quickest? Which chemical sub‐discipline offers most jobs? Reliable answers for these and other questions have been derived from the first European employment survey for chemists and chemical engineers, which was carried out in 2013. Here we publish the first general evaluation of the results of this survey.     

The Moduli Space of Six-Dimensional Two-Step Nilpotent Lie Algebras

We determine the moduli space of metric two-step nilpotent Lie algebras of dimension up to 6. This space is homeomorphic to a cone over a four-dimensional contractible simplicial complex. Moreover, we exhibit standard metric representatives of the seven isomorphism types of six-dimensional two-step nilpotent Lie algebras within our picture. Mathematics Subject Classifications (2000): Primary 22E25, 53C30, 22E60     

Vortex-assisted liquid-liquid microextraction of octylphenol, nonylphenol and bisphenol-A

A new and fast equilibrium-based solvent microextraction technique termed vortex-assisted liquid-liquid microextraction (VALLME) has been developed and used for the trace analysis of octylphenol, nonylphenol and bisphenol-A in water and wastewater samples. According to VALLME, dispersion of microvolumes of a low density extractant organic solvent into the aqueous sample is achieved by using for the first time vortex mixing, a mild emulsification procedure. The fine droplets formed could extract target analytes towards equilibrium faster because of the shorter diffusion distance and larger specific surface area. Upon centrifugation the floating extractant acceptor phase restored its initial single microdrop shape and was used for high-performance liquid chromatographic analysis. Different experimental parameters were controlled and the optimum conditions found were: 50 μl of octanol as the extractant phase; 20 ml aqueous donor samples; a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; centrifugation for 2 min at 3500 rpm; no ionic strength or pH adjustment. The calculated calibration curves gave high levels of linearity yielding correlation coefficients (r²) greater than 0.9935. The repeatability and reproducibility of the proposed method were found to be good and the limits of the detection were calculated in the low μg l⁻¹ level ranging between 0.01 and 0.07 μg l⁻¹. Matrix effects were determined by applying the proposed method to spiked tap, river water and treated municipal wastewater samples. The proposed method was finally applied to the determination of target pollutants in real wastewater effluent samples using the standard addition method.