Determination of anisotropic optical constants and surface coverage of molecular films using polarized visible ATR spectroscopy. Application to adsorbed cytochrome c films

This article describes a method to determine the anisotropic optical constants and surface coverage of molecular films using polarized attenuated total reflectance (ATR) absorbance measurements. We have extended the transfer-matrix formalism to describe birefringent and dichroic films in ATR geometries and have combined it with an iterative numerical procedure to determine the anisotropic values of both the real (n) and imaginary (k) parts of the complex refractive index of the film under investigation. Anisotropic values of the imaginary part of the refractive index (k) allow for the determination of the surface coverage and one order parameter of the film. To illustrate this approach, we have used cytochrome c (cyt c) protein films adsorbed to glass and indium tin oxide (ITO) surfaces. Experimental results show that cyt c films on these surfaces, which were formed under identical conditions, have significant differences in their surface coverages (11.2 +/- 0.4 pmol/cm(2) on glass and 21.7 +/- 0.9 pmol/cm(2) on ITO); however, their order parameters are similar (0.30 +/- 0.02 on glass and 0.36 +/- 0.04 on ITO).     

The shielding effect of glycerol against protein ionization in electrospray mass spectrometry

Most commercial recombinant proteins used as molecular biology tools, as well as many academically made preparations, are generally maintained in the presence of high glycerol concentrations after purification to maintain their biological activity. The present study shows that larger proteins containing high concentrations of glycerol are not amenable to analysis using conventional electrospray ionization mass spectrometry (ESI-MS) interfaces. In this investigation the presence of 25% (v/v) glycerol suppressed the signals of Taq DNA polymerase molecules, while 1% (v/v) glycerol suppressed the signal of horse heart myoglobin. The signal suppression was probably caused by the interaction of glycerol molecules with the proteins to create a shielding effect that prevents the ionization of the basic and/or acidic groups in the amino acid side chains. To overcome this difficulty the glycerol concentration was decreased to 5% (v/v) by dialyzing the Taq polymerase solution against water, and the cone voltage in the ESI triple-quadrupole mass spectrometer was set at 80-130 V. This permitted observation of a mass spectrum that contained ions corresponding to protonation of up to 50% of the ionizable basic groups. In the absence of glycerol up to 85% of the basic groups of Taq polymerase became ionized, as observed in the mass spectrum at relatively low cone voltages. An explanation of these and other observations is proposed, based on strong interactions between the protein molecules and glycerol. For purposes of comparison similar experiments were performed on myoglobin, a small protein with 21 basic groups, whose ionization was apparently suppressed in the presence of 1% (v/v) glycerol, since no mass spectrum could be obtained even at high cone voltages.     

Atom-Economic Synthesis of Functionalized Octahydroacridines from Citronellal or 3-(Phenylthio)-citronellal

Here we present a simple, solvent-free, one-pot, hetero-Diels–Alder reaction of (R)-citronellal or 3-(phenylthio)-citronellal with arylamines using solid-supported catalyst (SiO₂/ZnCl₂). This general, efficient, and improved method is selective, affording preferentially new trans-fused 3-(phenylthio)-octahydroacridines (S-OHAs) in good yields. The use of microwave irradiation facilitates the procedure and accelerates the reaction.     

Exhaustive electrolysis for recovery of actinides from molten LiCl–KCl using solid aluminium cathodes

An electrorefining process in molten chloride salts using solid aluminium cathodes is being developed in Institute for Transuranium Elements in order to separate actinides (An) from spent nuclear fuel. In this process, the fuel including fission products (FP) is dissolved into an electrolyte. Without purification of the salt, the process would have to be stopped when the FP concentration would become too high to allow a selective deposition of An on the cathode. Exhaustive electrolysis is proposed as the first purification step, consisting of a group-selective recovery of An on solid aluminium cathodes. On the anodic side, chlorine gas is produced by electrochemical decomposition of the salt. In order to prove the feasibility of the method, two galvanostatic electrolyses were carried out and the potentials of both electrodes were constantly monitored. Uranium was recovered from LiCl–KCl melts containing UCl₃ and a mixture of UCl₃–NdCl₃, in which its concentration decreased from 1.7 to 0.1 wt% with no co-deposition of neodymium. Although the maximum applicable current densities were relatively low, the results are promising, demonstrating high current efficiency and selectivity of the proposed method. A design and application of a special chlorine gas producing inert anode is also discussed.     

Focused microwave irradiation-assisted synthesis of N-cyclohexyl-1,2,4-oxadiazole derivatives with antitumor activity

A facile synthesis of 3,5-disubstituted 1,2,4-oxadiazole derivatives under focused microwave irradiation (FMWI) is reported. Arylamidoximes 1a–i and dicyclohexylcarbodiimide (DCC) were carried out in DMF under FMWI to obtain 1,2,4-oxadiazoles 2a–i in 61–81% yields. All compounds exhibited antiproliferative activities in vitro against three human cancer cell lines HCT-116, PC-3, and SNB-19.     

Bethe Ansatz Solution of Discrete Time Stochastic Processes with Fully Parallel Update

We present the Bethe ansatz solution for the discrete time zero range and asymmetric exclusion processes with fully parallel dynamics. The model depends on two parameters: p, the probability of single particle hopping, and q, the deformation parameter, which in the general case, |q| < 1, is responsible for long range interaction between particles. The particular case q = 0 corresponds to the Nagel-Schreckenberg traffic model with v _max = 1. As a result, we obtain the largest eigenvalue of the equation for the generating function of the distance travelled by particles. For the case q = 0 the result is obtained for arbitrary size of the lattice and number of particles. In the general case we study the model in the scaling limit and obtain the universal form specific for the Kardar-Parisi-Zhang universality class. We describe the phase transition occurring in the limit p→ 1 when q < 0.     

Capillary electromigration methods for fatty acids determination in vegetable and marine oils: A review

Fatty acids determination is of paramount importance for quality control and suitable labeling of edible oils, required by regulatory agencies in several countries, and fast methods for this determination are worldly desired. This review article aimed to explore the available analytical methods for vegetable and marine oils analyses employing CE, which can be a straightforward and faster alternative than GC methods for fatty acid determination, considering some purposes. CE usually offers the possibility of a rapid analysis with a simple preparation of the sample, without requiring specific columns, which are inherent advantages of the technique. Instrumental conditions and the key points about fatty acids determination employing the technique are highlighted, and the main challenges and perspectives are also approached. Potential use of CE for edible oil analyses has been demonstrated for research and routine, which can be of interest for industries, regulatory agencies, and edible oil researchers. Therefore, we have explored the analytical approaches described in the last decades, intending to spread the interest of CE methods for fatty acid monitoring, label accuracy assessment, and food authenticity evaluation of edible oils.