Aktuelle Meldungen / en-gb Uni Köln Sun, 19 Aug 2018 00:02:41 +0200 Sun, 19 Aug 2018 00:02:41 +0200 TYPO3 EXT:news news-165 Tue, 17 Jul 2018 16:22:32 +0200 Article Published in the ACerS Bulletin on the International Rhine Ceramic Round Table http://mathur.uni-koeln.de/index.php?id=news-detail10&tx_news_pi1%5Bnews%5D=165&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=159419cfacc1a5bfd09f06957d82e0bc Representatives of The American Ceramic Society (ACerS), the European Ceramic Society (ECerS), the German Ceramic Society (DKG) and the German Materials Society (DGM) joined the International Rhine Ceramic Round Table to discuss, share, and coordinate ideas and initiatives on promoting ceramic science and technology at an international and interdisciplinary level. The International Rhine Ceramic Round Table, with globally acclaimed professional voices, initiated an important discussion on the most critical challenges of science and technology of functional materials and ceramics. More importantly, this expert group underlined the role of professional societies in enabling open innovation and global collaboration for augmenting professional recognition and visibility of the field. All panel members and attendees agreed to maintain a more thorough and continuous exchange and supported the agenda “act locally, connect globally” with the aim of increasing the value proposition for members and catering to the pressing needs of diversity and internationalization.

This article is originally published in the ACerS Bulletin and we acknowledge the permission of the American Ceramic Society to post the content on our website.

 

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news-164 Thu, 12 Jul 2018 13:30:24 +0200 New Paper Published in RSC Advances http://mathur.uni-koeln.de/index.php?id=news-detail10&tx_news_pi1%5Bnews%5D=164&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=b1f66ce50a187f4f0ae2357f7fb44b61 Hollow silica capsules for amphiphilic transport and sustained delivery of antibiotic and anticancer drugs. Gessner, I.; Krakor, E.; Jurewicz, A.; Wulff, V.; Kling, L.; Christiansen, S.; Brodusch, N.; Gauvin, R.; Wortmann, L.; Wolke, M.; Plum, G.; Schauss, A.; Krautwurst, J.; Ruschewitz, U.; Ilyas, S.; Mathur, S.

Abstract

Hollow mesoporous silica capsules (HMSC) are potential drug transport vehicles due to their biocompatibility, high loading capacity and sufficient stability in biological milieu. Herein, we report the synthesis of ellipsoid-shaped HMSC (aspect ratio 2) performed using hematite particles as solid templates that were coated with a conformal silica shell through cross-condensation reactions. For obtaining hollow silica capsules, the iron oxide core was removed by acidic leaching. Gas sorption studies on HMSC revealed mesoscopic pores (main pore width 38 Å) and a high surface area of 308.8 m2 g−1. Cell uptake of dye-labeled HMSC was confirmed by incubating them with human cervical cancer (HeLa) cells and analyzing the internalization through confocal microscopy. The amphiphilic nature of HMSC for drug delivery applications was tested by loading antibiotic (ciprofloxacin) and anticancer (curcumin) compounds as model drugs for hydrophilic and hydrophobic therapeutics, respectively. The versatility of HMSC in transporting hydrophilic as well as hydrophobic drugs and a pH dependent drug release over several days under physiological conditions was demonstrated in both cases by UV-vis spectroscopy. Ciprofloxacin-loaded HMSC were additionally evaluated towards Gram negative (E. coli) bacteria and demonstrated their efficacy even at low concentrations (10 μg ml−1) in inhibiting complete bacterial growth over 18 hours.

 

RSC Advances 2018, 8, 24883--24892.

https://doi.org/10.1039/C8RA03716G

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news-163 Thu, 12 Jul 2018 13:26:48 +0200 New Paper Published in Sensors and Actuators B: Chemical http://mathur.uni-koeln.de/index.php?id=news-detail10&tx_news_pi1%5Bnews%5D=163&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=a0ba72412aa4dba29ecadee4ef888816 Bulk detection of explosives and development of customized metal oxide semiconductor gas sensors for the identification of energetic materials Konstantynovski, K.; Njio, G.; Börner, F.; Lepcha, A.; Fischer, T.; Holl, G.; Mathur, S.  

Abstract

Based on previous work, a setup allowing discrimination between energetic and non-energetic materials was developed. In order to cover novel materials not yet included in databases, a library free approach was chosen. The evaluation of explosion hazards for solid and liquid samples in the lowest milligram range was carried out by relying on the response of the substances towards thermal activation rather than on their chemical nature. The reaction was monitored by a combination of metal oxide semiconductor (MOX) gas sensors, photodiodes and a pressure sensor. Utilization of ambient air as a carrier gas and indirect control over sample weight by the geometry of the heater allow uncomplicated handling under real working conditions. In the first phase readily available physical and chemical sensors were applied. The rate of correct assignments was 99.8% with no false negatives and only 1 false positive out of 475 experiments. The possibility of library free operation was also confirmed by an additional series of experiments on materials not used for training the system. In the second phase the readily available MOX gas sensors were replaced by custom designed ones, which allowed single substances and classes of energetic materials by means to be discriminated by means of principal component analysis (PCA).

 

Sensors and Actuators B: Chemical 2018, 258, 1252-1266.

https://doi.org/10.1016/j.snb.2017.11.116

© 2018 Elsevier Ltd. All rights reserved.

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news-162 Thu, 12 Jul 2018 13:20:58 +0200 New Paper Published in Electrochimica Acta http://mathur.uni-koeln.de/index.php?id=news-detail10&tx_news_pi1%5Bnews%5D=162&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=34f2f130844c0a7bf0d0e81a297f3baa Bismuth Oxychloride/MXene Symmetric Supercapacitor with High Volumetric Energy Density. Xia, Q.; Shinde, N. M.; Yun, J.; Zhang, T. F.; Mane, R. S.; Mathur, S.; Kim, K. H.  

Abstract

Since the discovery of two-dimensional (2D) graphene, a new class of 2D materials with excellent electrical conductivity has recently been attracting attention in studying promising electrode materials in energy storage applications. Herein, bismuth oxychloride nanosheets-immobilised Ti3C2Tx MXene material (TCBOC) is synthesised by a facile and cost-effective chemical bath deposition (CBD) route. The bismuth oxychloride (BiOCl) nanosheets are grown and immobilised on surfaces of Ti3C2Tx-MXene flakes. An electrode based on the TCBOC nanocomposite exhibited a remarkably volumetric specific capacitance of 396.5 F cm-3 at 1 A g−1 and 228.0 F cm-3 at 15 A g−1. Furthermore, a symmetric supercapacitor (SSC) assembled using TCBOC material proves to have a high energy density of 15.2 Wh kg−1 at a power density of 567.4 W kg−1 compared to SSCs using previously reported Ti3C2Tx MXene materials. The SSC shows cycle life retention of 85.0% after 5000 cycles (at 5 A g−1). The enhanced capacitive performance is attributed to the increased surface area due to BiOCl nanosheets anchored on a 2D MXene surface, the activities of BiOCl sheets, and the excellent conductivity of a Ti3C2Tx MXene material.

 

Electrochimica Acta 2018, 271.

https://doi.org/10.1016/j.electacta.2018.03.168

© 2018 Elsevier Ltd. All rights reserved.

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news-161 Thu, 12 Jul 2018 13:14:54 +0200 New Paper Published in IEEE Transactions on Nanotechnology http://mathur.uni-koeln.de/index.php?id=news-detail10&tx_news_pi1%5Bnews%5D=161&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=c22a04bee947879e2357a5758ddaccc4 UV/IR Dual-Wavelength Photodetector Design Based on a ZnO/PMMA/PbSe Nanocomposite Dolatyari, M.; Rostami, A.; Mathur, S.; Klein, A.

Abstract

A UV/IR dual-wavelength photodetector based on a ZnO/PMMA/PbSe nanocomposite [PMMA = poly(methyl methacrylate)] for simultaneous detection of 190-400 nm UV and 3-5 µm IR radiation is presented. For UV detection spherical nanoparticles of boron-doped ZnO (B-ZnO) were synthesized and stabilized using hexamethylenetetramine (HMTA). The absorption intensity in the UV-vis range is increased upon B doping and DFT calculations confirm the results. Responsivity of the fabricated UV detector is 7.8 AW and the detector gain is 26.49 at a 365 nm input wavelength. For the synthesis of IR detecting PbSe a new method was worked out, including the stabilization of the particles with thioacetamide (TAA). The performance of the PbSe based IR detector turns out to be superior to previously reported PbSe based detectors synthesized by established methods. The responsivity and gain of the detector is 8 AW and 3.31 respectively for 3-5 µm incident wavelength. The sensitivity is 30 for IR detection and overall this sensitivity is excellent for sensing in the mid-IR range. All three "chemical factors", the B-doping, the synthesis conditions for nanoparticles and the surface modification have contributed to the excellent optoelectronic performance of these new photodetector devices, while the PMMA layer turned out to be very effectively reducing the noise for IR detection.

 

IEEE Transactions on Nanotechnology (Volume: 17, Issue: 3, May 2018).

DOI: 10.1109/TNANO.2018.2827201

Copyright © 2018, IEEE


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