New Poly(N-isopropylacrylamide-butylacrylate) Copolymer Biointerfaces and Their Characteristic Influence on Cell Behavior In Vitro

Designing and obtaining new synthetic smart biointerfaces with specific and controlled characteristics relevant for applications in biomedical and bioengineering domains represents one of the main challenges in these fields. In this work, Matrix-Assisted Pulsed Laser Evaporation (MAPLE) is used to obtain synthetic biointerfaces of poly(N-isopropyl acrylamide-butyl acrylate) p(NIPAM-BA) copolymer with different characteristics (i.e., roughness, porosity, wettability), and their effect on normal HEK 293 T and murine melanoma B16-F1 cells is studied. For this, the influence of various solvents (chloroform, dimethylsulfoxide, water) and fluence variation (250–450 mJ/cm²) on the morphological, roughness, wettability, and physico–chemical characteristics of the coatings are evaluated by atomic force microscopy, scanning electron microscopy, contact angle measurements, Fourier-transform-IR spectroscopy, and X-ray photoelectron spectroscopy. Coatings obtained by the spin coating method are used for reference. No significant alteration in the chemistry of the surfaces is observed for the coatings obtained by both methods. All p(NIPAM-BA) coatings show hydrophilic character, with the exception of those obtained with chloroform at 250 mJ/cm². The surface morphology is shown to depend on both solvent type and laser fluence and it ranges from smooth surfaces to rough and porous ones. Physico–chemical and biological analysis reveal that the MAPLE deposition method with fluences of 350–450 mJ/cm² when using DMSO solvent is more appropriate for bioengineering applications due to the surface characteristics (i.e., pore presence) and to the good compatibility with normal cells and cytotoxicity against melanoma cells.     

Microwave-Assisted Synthesis of Phenothiazine and Quinoline Derivatives

Application of a dynamic microwave power system in the chemical synthesis of some phenothiazine and quinoline derivatives is described. Heterocyclic ring formation, aromatic nucleophilic substitution and heterocyclic aldehydes/ketones condensation reactions were performed on solid support, or under solvent free reaction conditions. The microwave-assisted Duff formylation of phenothiazine was achieved. Comparison of microwave-assisted synthesis with the conventional synthetic methods demonstrates advantages related to shorter reaction times and in some cases better reaction yields.     

On the semantics of noun compounds

This paper provides new insights on the semantic characteristics of two and three noun compounds. An analysis is performed using two sets of semantic classification categories: a list of 8 prepositional paraphrases previously proposed by Lauer [Designing statistical language learners: experiments on noun compounds, Ph.D. Thesis, Macquarie University, Australia] and a new set of 35 semantic relations introduced by us. We show the distribution of these semantic categories on a corpus of noun compounds and present several models for the bracketing and the semantic classification of noun compounds. The results are compared against state-of-the-art models reported in the literature.     

Production issues for high aspect ratio Lobster-eye optics using LIGA

 A square packed array of square-channels with long channel axis aligned radially is a useful structure for condensing grazing incidence flux to a focus. These devices, known as Lobster-eye optics for their similarity to the eyes of the macruran crustaceans, show great promise as the focusing optic in the next generation of X-ray all-sky monitors. At X-ray wavelengths the optimal Lobster-eye structure requires an aspect ratio of channel length to width of greater than 30:1. Following recent success in fabricating a low aspect ratio Lobster-eye structure, we discuss some of the parameters for, and production issues involved in making, a useful Lobster-eye prototype using LIGA. We report on our initial attempts to produce high aspect ratio Lobster-eye optics using the LIGA process with a graphite substrate. Received: 10 August 2001/Accepted: 24 September 2001 AGP gratefully acknowledges receipt of an ARC post-doctoral fellowship. This work was supported by the Australian Synchrotron Research Program, which is funded by the Commonwealth of Australia under the Major National Research Facilities Program. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Basic Energy Sciences, Office of Energy Research, under Contract No. W-31-109-Eng-38. This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

Development of a freestanding copper antiscatter grid using deep X-ray lithography

A prototype freestanding copper antiscatter grid with parallel lamellar walls has been fabricated using deep X-ray lithography and electroforming. The freestanding copper grid has square shaped lamellar walls that are 25 m thick and 1 mm tall with a 550 m period. For mammography applications, the lamellar walls have to be aligned to a point X-ray source of the X-ray system. To achieve this goal, we investigated a dynamic double-exposure technique. Our progress in using stacked exposures and use of the photoresist SU-8, both to reduce fabrication cost, is also presented.We would like to thank Francesco De Carlo, Judith Yaeger, Joseph Arko and Shenglan Xu for their assistance. Use of the APS was supported by US Department of Energy, Office of Sciences, under Contract No. W-31-109-ENG-38. We thank SRI CAT for the support of this research. The work is supported by NIH SBIR Phase II Grants: 2 R44 CA76752-02 and 5 R44 CA76752-03.This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

Bioaccumulation of palladium, platinum and rhodium from urban particulates and sediments by the freshwater isopod Asellus aquaticus.

The three-way catalytic converters introduced to oxidize and reduce gaseous automobile emissions represent a source of platinum group elements (PGEs), in particular platinum, palladium and rhodium, to the urban environment. Abrasion of automobile exhausts leads to an increase of the concentration of PGEs in environmental matrices such as vegetation, soil and water bodies. The bioaccumulation of Pd, Pt and Rh by the freshwater isopod Asellus aquaticus was studied in natural ecosystems and under laboratory conditions. Owing to the low concentration level (ng g(-1)) of PGEs in the animals studied. analyses were performed with a quadrupole inductively coupled plasma mass spectrometry (ICP-MS) and hafnium, copper, yttrium, rubidium, strontium and lead were monitored for spectral interference correction. Asellus aquaticus collected in an urban river showed a content (mean +/- s) of 155.4 +/- 73.4, 38.0 +/- 34.6, and 17.9 +/- 12.2 ng g(-1) (dry weight) for Pd, Pt and Rh, respectively. The exposure of Asellus aquaticus to PGE standard solutions for a period of 24h give bioaccumulation factors of Bf: 150, 85, and 7 for Pd, Pt and Rh, respectively. Exposure of Asellus aquaticus to environmental samples for different exposure periods demonstrated that PGE bioaccumulation is time dependent. and shows a higher accumulation for the materials with a higher PGE content. While all three elements have the same uptake rate for exposure to catalyst materials, for exposure to environmental materials they havc a different uptake rate which can be attributed to transformations of the PGE species in the environment.     

Ka-band analog front-end for software-defined direct conversion receiver

A six-port Ka-band front-end architecture based on direct conversion for a software-defined radio application is proposed in this paper. The direct conversion is accomplished using six-port technology. In order to demodulate various phase-shift-keying/quadrature-amplitude-modulation (PSK/QAM) modulated signals at a high bit rate, a new analog baseband circuit was specially designed according to the I/Q equations presented in the theoretical part. An experimental prototype has been fabricated and measured. Simulation and measurement results for binary PSK, quaternary PSK (QPSK), 8 PSK, 16 PSK, and 16 QAM modulated signals at a bit rate up to 40 Mb/s are presented to validate the proposed approach. A software-defined radio can be designed using the new front-end and only two analog-to-digital converters (ADCs) because the I/Q output signals are generated by analog means. Previous six-port receivers make use of four ADCs to read the six-port dc levels and require digital computations to generate the I/Q output signals. With the proposed approach, the load of the signal processor will therefore be reduced and the modulation speed can be significantly increased using the same digital signal processor.