193-nm lithography

The trend in microelectronics toward printing features 0.25 μm and below has motivated the development of lithography at the 193-nm wavelength of argon fluoride excimer lasers. This technology is in its early stages, but a picture is emerging of its strengths and limitations. The change in wavelength from 248 to 193 nm will require parallel progress in projection systems, optical materials, and photo-resist chemistries and processes. This paper reviews the current status of these various topics as they have been engineered under a multiyear program at MIT Lincoln Laboratory     

Magnetite core-shell nano-composites with chlorine functionality: preparation by miniemulsion polymerization and characterization

Magnetic composite particles with a magnetic core consisting of superparamagnetic iron oxide and a cover layer of hydrophobic polyvinylbenzylchloride are described. The magnetite was prepared by precipitation starting with mixed iron II and iron III salts and coating of the solid with oleic acid. The coating is conducted via the liquid–liquid phase transfer. Thereby oleic acid adsorbed on the magnetite surface. In a second step the oleic acid treated magnetite was coated with polyvinylbenzylchloride in a miniemulsion polymerization to get a protective layer. The obtained magnetite core-shell nano-composites with chlorine functionality were characterized by different methods: particle size measurement, acid treatment, iron content, morphology and elemental profiles across the composite particles diameter. The test result reveals the binding of the iron oxide inside the composites which can be also recognize in TEM pictures.     

Potential use of chemical cues for colony-mate recognition in the big brown bat,Eptesicus fuscus

Bats should benefit from recognition of their roost-mates when colonies form stable social units that persist over time. We used Y-maze experiments and gas chromatography–olfactometry (GC-O) to evaluate whether female big brown bats Eptesicus fuscus (Chiroptera: Vespertilionidae) use chemical cues to distinguish among conspecifics. In dual-choice Y-maze experiments, females chose the scent of another female from their own roost over a conspecific female from a different roost in a majority of trials. Analysis of total body odors using GC-O suggests that individuals from a given colony may share a more common odor signature with roost-mates than with non-roost-mate conspecifics. Using four principle components derived from 15 odor variables, discriminant function analysis correctly assigned most individuals to the correct colony.     

Chemically modified babassu coconut (<Emphasis Type="Italic">Orbignya sp.)</Emphasis> biopolymer: characterization and development of a thin film for its application in electrochemical sensors

The babassu coconut is a plant very abundant in northeast of Brazil and other countries, and any part of plant and fruit becomes residue. In this study, babassu mesocarp (Orbignya sp) (BM) was chemically modified with phthalic anhydride (BMPA) to increase its solubility in an aqueous medium, and thus facilitate its processing in the form of thin films. The reaction of modification of the babassu mesocarp with phthalic anhydride (PA), obtaining BMPA, was confirmed by FTIR, XRD, TG/DTG, Zeta Potential and SEM analysis, from the differences in the bands of the FTIR spectra, increase in crystallinity, new thermal profile, changes in zeta potential value and morphology, respectively. The thin monolayer films of BM and BMPA were produced by the self-assembly monolayer (SAM) technique, and adsorbed onto conductive glass substrates (tin-doped indium oxide, ITO). The electroactive properties of these thin films were evaluated by cyclic voltammetry (CV). BM exhibited a pair redox pair process of +0.57 V(oxidation) and?+?0.19 V (reduction) for BM. In BMPA these redox processes were observed at +0.37 V (oxidation) and 0.24 V vs. ECS (reduction), verifying that both BM and BMPA are electroactive materials that can be used in the construction of sensor platforms, without the necessity of being conjugated with other electroactive materials, such as conductive polymers, metal phthalocyanines, or dyes. Furthermore, under the experimental conditions used, the BMPA presented a more reversible redox process and higher electrochemical stability in comparison to BM. This effect occurs because BMPA has higher solubility in aqueous media, which favors the preparation of films with smaller grain sizes compared to BM films, as observed by Atomic Force Microscopy (AFM). This study showed that BMPA is a new material with potential for applications in electrochemical sensors.

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Graphical abstract Obtaining and modifying babassu mesocarp for the electrochemical studies

     

Chlor-alkali electrolysis with oxygen depolarized cathodes: history,present status and future prospects

The historical development, current status and future prospects of chlor-alkali electrolysis with oxygen depolarized cathodes (ODCs) are summarized. Over the last decades, membrane chlor-alkali technology has been optimized to such an extent that no substantial reduction of the energy demand can be expected from further process modifications. However, replacement of the hydrogen evolving cathodes in the classical membrane cells by ODCs allows for reduction of the cell voltage and correspondingly the energy consumption of up to 30%. This replacement requires the development of appropriate cathode materials and novel electrolysis cell designs. Due to their superior long-term stability, ODCs based on silver catalysts are very promising for oxygen reduction in concentrated NaOH solutions. Finite-gap falling film cells appear to be the technically most mature design among the several ODC electrolysis cells that have been investigated.

Inhibitors of inducible NO synthase expression: total synthesis of (S)-curvularin and its ring homologues

(S)-Curvularin and its 13-, 14-, and 16-membered lactone homologues were synthesized through a uniform strategy in which a Kochi oxidative decarboxylation and ring-closing metathesis reactions constitute the key processes. In the evaluation of the anti-inflammatory effects of the synthesized compounds in assays using cells stably transfected with a human iNOS promoter-luciferase reporter gene construct, the 14- and 16-membered homologues showed a slightly higher inhibitory effect towards iNOS promoter activity than curvularin itself. However, the larger ring homologues also exhibited higher cytotoxicity, manifest in downregulated eNOS promoter activity. In contrast, the di-O-acetyl and 4-chloro derivatives of (S)-curvularin showed higher inhibitory efficiency towards induction of the iNOS promoter and less negative effect on eNOS promoter activity than curvularin.     

μ‐Consortium: Aufbau einer mobilen Anlage für die Aus‐ und Weiterbildung in der Mikroverfahrenstechnik

A mobile plant for practical training was developed as part of the project μ‐Consortium to integrate micro process engineering into teaching. Lab experiments in the fields of mixing and homogenous reactions, heterogeneous reactions, heat transfer and particle synthesis were worked out to impart knowledge of different process‐engineering operations.     

Thermal and dynamic mechanical behavior of epoxy composites reinforced with post-consumed yerba mate

Yerba mate (YM) is widely consumed in Latin American countries, and its residues can be used as bio-resources such as reinforced in epoxy composites. The present work aims to produce epoxy resin composites and evaluate the influence of post-consumed YM as reinforcement. The concentrations of YM used were 5, 10, and 20% (wt/wt). Chemical, thermal, morphological, and dynamic mechanical behaviors were explored. The YM incorporation did not influence chemically on the epoxy structure and a pull-out phenomenon was observed as YM content increased. The YM at lower concentrations (5 and 10%) led to higher values of activation energies calculated from model-free isoconversional methods. On the other hand, the composite e/YM 20 wt% improved all dynamic-mechanical properties. YM proved to be a suitable and cheap reinforcement for epoxy resin.     

Laser structuring of crystalline silicon thin-film solar cells on opaque foreign substrates

Crystalline silicon thin-film solar cells were fabricated on graphite substrates. A laser ablation process was developed for edge isolation of the thin-film cells. The shunt resistance was comparable to otherwise identical cells isolated by plasma etching, while the reproducibility of the laser isolation process was higher. The solar cells were characterized by current-voltage and light beam induced current measurements (LBiC). No interference was detected along the ablated edges. Spatial variations of the minority carrier lifetime are attributed to the grain structure of the seeding layer obtained by the zone melting recrystallization (ZMR).