Quantitative elemental analysis of individual particles with the use of micro‐beam X‐ray fluorescence method and Monte Carlo simulation

The aim of the work was to develop a Monte Carlo (MC) method and combine it with micro‐beam X‐ray fluorescence (XRF) technique for determination of chemical composition of individual particles. A collection of glass micro‐spheres, made of NIST (National Institute of Standards and Technoly) K3089 material of known chemical composition, with diameters in the range of 25–45 µm was investigated. The micro‐spheres were measured in a scanning micro‐beam XRF spectrometer utilising X‐ray tube as a source of primary radiation. Results obtained for low Z elements showed high dependence on particle size. It was found that the root mean square of concentration uncertainty, for the all elements present in the particle, increases with growing sample size. More accurate results were obtained for high Z elements such as Fe–Pb, as compared to others. The elemental percentage uncertainty did not exceed 14% for any particular sample and 6% for the whole group of the measured micro‐spheres as an average. Results obtained by the Monte Carlo method were compared with other analytical approaches. Copyright © 2009 John Wiley & Sons, Ltd.     

Modeling the electronic structures of the ground and excited states of the ytterbium atom and the ytterbium dimer: A modern quantum chemistry perspective

We present a comprehensive theoretical study of the electronic structures of the Yb atom and the Yb₂ molecule, respectively, focusing on their ground and lowest-lying electronically excited states. Our study includes various state-of-the-art quantum chemistry methods such as CCSD, CCSD(T), CASPT2 (including spin-orbit coupling), and EOM-CCSD as well as some recently developed pCCD-based approaches and their extensions to target excited states. Specifically, we scan the lowest-lying potential energy surfaces of the Yb₂ dimer and provide a reliable benchmark set of spectroscopic parameters including optimal bond lengths, vibrational frequencies, potential energy depths, and adiabatic excitation energies. Our in-depth analysis unravels the complex nature of the electronic spectrum of Yb₂, which is difficult to model accurately by any conventional quantum chemistry method. Finally, we scrutinize the bi-excited character of the first excited state and its evolution along the potential energy surface.     

Synthesis of Polycyclic Monothioimides via a Domino Reaction of β-Aminocycloalkenethioamides

Summary. Tricyclic cyclopenta[b]pyrrolo[3,4-c]pyridine-3,5-dione and pyrrolo[3,4-d]quinoline-3,5-diones with stable hemiaminal function or bicyclic azaspiro[4.4]nonanes and azaspiro[4.5]decanes were obtained in a domino reaction of cycloalkenecarbothioamides with maleimides. The proposed mechanism involves Michael addition, ring transformation, aqueous hydrolysis of the imine, and additional ring closure which is observed exclusively for one diastereoisomer.     

Phenolic Composition and Biological Properties of Wild and Commercial Dog Rose Fruits and Leaves

Rosa canina L. (dog rose) is a rich source of phenolic compounds that offer great hope for the prevention of chronic human diseases. Herein, wild and commercial samples of dog rose were chemically characterized with respect to their phenolic composition by liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (LC-DAD-ESI/MS). Furthermore, in vitro antioxidant properties and antibacterial activity of dog rose fruits and leaves hydromethanolic extracts and infusions were also evaluated. The results revealed that wild and commercial fruits of dog rose are similar in terms of l(+)-ascorbic acid, total phenolics (TPC), total flavonoids (TFC) and total phenolic acids (TPAC) content, individual phenolic constituents and antioxidant activity. Moreover, the fruits had lower levels of phenolic compounds and also revealed lower biological activity than the leaves. On the other hands, the highest content of TPC, TFC, TPAC, individual phenolic constituents, DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity and FRAP (ferric reducing antioxidant power) were found in the leaf’s infusions. They were also the only ones to show antibacterial activity. Overall, these finding confirmed usefulness of R. canina L. leaves and fruits as a rich source of bioactive phenolic compounds with potential use in food, pharmaceutical, and cosmetic industries.     

The Overexpression of YALI0B07117g Results in Enhanced Erythritol Synthesis from Glycerol by the Yeast Yarrowia lipolytica

The unconventional yeast Yarrowia lipolytica is used to produce erythritol from glycerol. In this study, the role of the erythrose reductase (ER) homolog YALI0B07117g in erythritol synthesis was analyzed. The deletion of the gene resulted in an increased production of mannitol (308%) and arabitol (204%) before the utilization of these polyols began. The strain overexpressing the YALI0B07117g gene was used to increase the erythritol yield from glycerol as a sole carbon source in batch cultures, resulting in a yield of 0.4 g/g. The specific consumption rate (qs) increased from 5.83 g/g/L for the WT strain to 8.49 g/g/L for the modified strain and the productivity of erythritol increased from 0.28 g/(L h) for the A101 strain to 0.41 g/(L h) for the modified strain. The application of the research may prove positive for shortening the cultivation time due to the increased rate of consumption of the substrate combined with the increased parameters of erythritol synthesis.     

Using self-assembled monolayers for controlled electrodeposition of copper into submicrometer size surface features/decrements

This work presents the application of alkanethiols for selectively masking the main surface of copper-seed-layer-covered silicon wafer, as used for the microprocessor production. The target of the investigation was to deposit copper only in the trenches and vias (channels of various shape) of micrometer size and not over the entire surface as in the presently used methods. The procedure developed starts with filling the trenches and vias with water, which is followed by dipping the wafers in a hexane solution containing dissolved dodekanetiol. Alkanetiol adsorbs and self-organizes on copper not protected with water and blocks the electroreduction of copper ions from the bath. The trenches and vias are free from adsorbed alkanetiols due to their very limited solubility in water. The surface-blocking process works very well and may effectively simplify the copper electrodeposition for microelectronic applications. The selective electrodeposition of copper accomplished by the proposed method significantly reduces the problems associated with the removal of excess of copper from the processed circuit elements.     

Appearance of topological phases in superconducting nanocircuits

We construct non-Abelian geometric transformations in superconducting nanocircuits, which resemble in properties the Aharonov-Bohm phase for an electron transported around a magnetic flux line. The effective magnetic fields can be strongly localized, and the path is traversed in the region where the energy separation between the states involved is at maximum, so that the adiabaticity condition is weakened. In particular, we present a scheme of topological charge pumping.     

Isotope selective ionization by optimal control using shaped femtosecond laser pulses

We report on selective optimization of different isotopes in an ionization process by means of spectrally broad shaped fs-laser pulses. This is demonstrated for (39,39)K2 and (39,41)K2 by applying evolution strategies in a feedback loop, whereby a surprisingly high enhancement of one isotope versus the other and vice versa is achieved (total factor approximately 140). Information about the dynamics on the involved vibrational states is extracted from the optimal pulse shapes, which provides a new spectroscopical approach of yielding distinct frequency pattern on fs-time scales. The method should, in principle, be feasible for all molecules.     

Pattern replication in blends of semiconducting and insulating polymers casted by horizontal dipping

Pattern replication in solution‐deposited thin films of insulating and conjugated polymer mixtures might provide an alternative to spatially resolved printing techniques for the fabrication of polymer‐based circuitries. Though it has been previously shown that phase separation in the course of spin‐casting leads to the formation of domain structures resembling the chemical patterns pre‐set on the film substrate, finding optimal casting conditions is a tedious process, which requires multiple sample preparations. Here, we have demonstrated pattern replication in a mixture of poly(3,3′′′‐didodecyl quarter thiophene) (PQT‐12) and deuterated poly(styrene‐co?4‐bromostyrene) (dPBrS) deposited by horizontal‐dipping on substrates, patterned with self‐assembling molecules by micro‐contact printing. Moreover, we show that casting conditions for accomplishing pattern replication can be efficiently screened by preparing thickness gradient samples. We have optimized the reconstruction of the substrate pattern in the PQT‐12:dPBrS film. Our results prove that desired structures of semiconducting and insulating polymers can be produced in a simple, high‐throughput technological process. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1419–1426