@article{SchulzeMakuchWagnerKounavesetal.2018, author = {Schulze-Makuch, Dirk and Wagner, Dirk and Kounaves, Samuel P. and Mangelsdorf, Kai and Devine, Kevin G. and de Vera, Jean-Pierre and Schmitt-Kopplin, Philippe and Grossart, Hans-Peter and Parro, Victor and Kaupenjohann, Martin and Galy, Albert and Schneider, Beate and Airo, Alessandro and Froesler, Jan and Davila, Alfonso F. and Arens, Felix L. and Caceres, Luis and Cornejo, Francisco Solis and Carrizo, Daniel and Dartnell, Lewis and DiRuggiero, Jocelyne and Flury, Markus and Ganzert, Lars and Gessner, Mark O. and Grathwohl, Peter and Guan, Lisa and Heinz, Jacob and Hess, Matthias and Keppler, Frank and Maus, Deborah and McKay, Christopher P. and Meckenstock, Rainer U. and Montgomery, Wren and Oberlin, Elizabeth A. and Probst, Alexander J. and Saenz, Johan S. and Sattler, Tobias and Schirmack, Janosch and Sephton, Mark A. and Schloter, Michael and Uhl, Jenny and Valenzuela, Bernardita and Vestergaard, Gisle and Woermer, Lars and Zamorano, Pedro}, title = {Transitory microbial habitat in the hyperarid Atacama Desert}, series = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {115}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {11}, publisher = {National Acad. of Sciences}, address = {Washington}, issn = {0027-8424}, doi = {10.1073/pnas.1714341115}, pages = {2670 -- 2675}, year = {2018}, language = {en} } @article{ReschkeMebsSigfridssonClaussetal.2017, author = {Reschke, Stefan and Mebs, Stefan and Sigfridsson-Clauss, Kajsa G. V. and Kositzki, Ramona and Leimk{\"u}hler, Silke and Haumann, Michael}, title = {Protonation and Sulfido versus Oxo Ligation Changes at the Molybdenum Cofactor in Xanthine Dehydrogenase (XDH) Variants Studied by X-ray Absorption Spectroscopy}, series = {Inorganic chemistry}, volume = {56}, journal = {Inorganic chemistry}, number = {4}, publisher = {American Chemical Society}, address = {Washington}, issn = {0020-1669}, doi = {10.1021/acs.inorgchem.6b02846}, pages = {2165 -- 2176}, year = {2017}, abstract = {Enzymes of the xanthine oxidase family are among the best characterized mononuclear molybdenum enzymes. Open questions about their mechanism of transfer of an oxygen atom to the substrate remain. The enzymes share a molybdenum cofactor (Moco) with the metal ion binding a molybdopterin (MPT) molecule via its dithiolene function and terminal sulfur and oxygen groups. For xanthine dehydrogenase (XDH) from the bacterium Rhodobacter capsulatus, we used X-ray absorption spectroscopy to determine the Mo site structure, its changes in a pH range of 5-10, and the influence of amino acids (Glu730 and Gln179) close to Moco in wild-type (WT), Q179A, and E730A variants, complemented by enzyme kinetics and quantum chemical studies. Oxidized WT and Q179A revealed a similar Mo (VI) ion with each one MPT, Mo=O, Mo-O-, and Mo=S ligand, and a weak Mo-O(E730) bond at alkaline pH. Protonation of an oxo to a hydroxo (OH) ligand (pK similar to 6.8) causes inhibition of XDH at acidic pH, whereas deprotonated xanthine (pK similar to 8.8) is an inhibitor at alkaline pH. A similar acidic pK for the WT and Q179A. variants, as well as the metrical parameters of the Mo site and density functional theory calculations, suggested protonation at the equatorial oxo group. The sulfido was replaced with an oxo ligand in the inactive E730A variant, further showing another oxo and one Mo OH ligand at Mo, which are independent of pH. Our findings suggest a reaction mechanism for XDH in which an initial oxo rather than a hydroxo group and the sulfido ligand are essential for xanthine oxidation.}, language = {en} } @misc{ZehbeKolloscheLardongetal.2017, author = {Zehbe, Kerstin and Kollosche, Matthias and Lardong, Sebastian and Kelling, Alexandra and Schilde, Uwe and Taubert, Andreas}, title = {Ionogels based on poly(methyl methacrylate) and metal-containing ionic liquids}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400607}, pages = {16}, year = {2017}, abstract = {Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs.}, language = {en} } @article{ZabelWinterKellingetal.2016, author = {Zabel, Andr{\´e} and Winter, Alette and Kelling, Alexandra and Schilde, Uwe and Strauch, Peter}, title = {Tetrabromidocuprates(II)-Synthesis, Structure and EPR}, series = {International journal of molecular sciences}, volume = {17}, journal = {International journal of molecular sciences}, number = {4}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/ijms17040596}, pages = {14}, year = {2016}, abstract = {Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.}, language = {en} } @misc{ZabelWinterKellingetal.2016, author = {Zabel, Andr{\´e} and Winter, Alette and Kelling, Alexandra and Schilde, Uwe and Strauch, Peter}, title = {Tetrabromidocuprates(II)-Synthesis, Structure and EPR}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-91470}, pages = {14}, year = {2016}, abstract = {Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.}, language = {en} } @phdthesis{Friess2016, author = {Frieß, Fabian}, title = {Shape-memory polymer micronetworks}, school = {Universit{\"a}t Potsdam}, pages = {xiv, 111 S.}, year = {2016}, language = {en} } @article{MeyerRaberEbertetal.2015, author = {Meyer, S. and Raber, G. and Ebert, Franziska and Leffers, L. and M{\"u}ller, Sandra Marie and Taleshi, M. S. and Francesconi, Kevin A. and Schwerdtle, Tanja}, title = {In vitro toxicological characterisation of arsenic-containing fatty acids and three of their metabolites}, series = {Toxicology research}, volume = {5}, journal = {Toxicology research}, number = {4}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2045-4538}, doi = {10.1039/c5tx00122f}, pages = {1289 -- 1296}, year = {2015}, abstract = {Arsenic-containing fatty acids are a group of fat-soluble arsenic species (arsenolipids) which are present in marine fish and other seafood. Recently, it has been shown that arsenic-containing hydrocarbons, another group of arsenolipids, exert toxicity in similar concentrations comparable to arsenite although the toxic modes of action differ. Hence, a risk assessment of arsenolipids is urgently needed. In this study the cellular toxicity of a saturated (AsFA 362) and an unsaturated (AsFA 388) arsenic-containing fatty acid and three of their proposed metabolites (DMAV, DMAPr and thio-DMAPr) were investigated in human liver cells (HepG2). Even though both arsenic-containing fatty acids were less toxic as compared to arsenic-containing hydrocarbons and arsenite, significant effects were observable at μM concentrations. DMAV causes effects in a similar concentration range and it could be seen that it is metabolised to its highly toxic thio analogue thio-DMAV in HepG2 cells. Nevertheless, DMAPr and thio-DMAPr did not exert any cytotoxicity. In summary, our data indicate that risks to human health related to the presence of arsenic-containing fatty acids in marine food cannot be excluded. This stresses the need for a full in vitro and in vivo toxicological characterisation of these arsenolipids.}, language = {en} } @misc{MeyerRaberEbertetal.2015, author = {Meyer, S. and Raber, G. and Ebert, Franziska and Leffers, L. and M{\"u}ller, Sandra Marie and Taleshi, M. S. and Francesconi, Kevin A. and Schwerdtle, Tanja}, title = {In vitro toxicological characterisation of arsenic-containing fatty acids and three of their metabolites}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-82008}, year = {2015}, abstract = {Arsenic-containing fatty acids are a group of fat-soluble arsenic species (arsenolipids) which are present in marine fish and other seafood. Recently, it has been shown that arsenic-containing hydrocarbons, another group of arsenolipids, exert toxicity in similar concentrations comparable to arsenite although the toxic modes of action differ. Hence, a risk assessment of arsenolipids is urgently needed. In this study the cellular toxicity of a saturated (AsFA 362) and an unsaturated (AsFA 388) arsenic-containing fatty acid and three of their proposed metabolites (DMAV, DMAPr and thio-DMAPr) were investigated in human liver cells (HepG2). Even though both arsenic-containing fatty acids were less toxic as compared to arsenic-containing hydrocarbons and arsenite, significant effects were observable at μM concentrations. DMAV causes effects in a similar concentration range and it could be seen that it is metabolised to its highly toxic thio analogue thio-DMAV in HepG2 cells. Nevertheless, DMAPr and thio-DMAPr did not exert any cytotoxicity. In summary, our data indicate that risks to human health related to the presence of arsenic-containing fatty acids in marine food cannot be excluded. This stresses the need for a full in vitro and in vivo toxicological characterisation of these arsenolipids.}, language = {en} } @misc{NiedlBeta2015, author = {Niedl, Robert Raimund and Beta, Carsten}, title = {Hydrogel-driven paper-based microfluidics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-81083}, pages = {2452 -- 2459}, year = {2015}, abstract = {Paper-based microfluidics provide an inexpensive, easy to use technology for point-of-care diagnostics in developing countries. Here, we combine paper-based microfluidic devices with responsive hydrogels to add an entire new class of functions to these versatile low-cost fluidic systems. The hydrogels serve as fluid reservoirs. In response to an external stimulus, e.g. an increase in temperature, the hydrogels collapse and release fluid into the structured paper substrate. In this way, chemicals that are either stored on the paper substrate or inside the hydrogel pads can be dissolved, premixed, and brought to reaction to fulfill specific analytic tasks. We demonstrate that multi-step sequences of chemical reactions can be implemented in a paper-based system and operated without the need for external precision pumps. We exemplify this technology by integrating an antibody-based E. coli test on a small and easy to use paper device.}, language = {en} } @article{NiedlBeta2015, author = {Niedl, Robert Raimund and Beta, Carsten}, title = {Hydrogel-driven paper-based microfluidics}, series = {LAB on a chip : miniaturisation for chemistry and biology}, volume = {11}, journal = {LAB on a chip : miniaturisation for chemistry and biology}, number = {15}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1473-0197}, doi = {10.1039/c5lc00276a}, pages = {2452 -- 2459}, year = {2015}, abstract = {Paper-based microfluidics provide an inexpensive, easy to use technology for point-of-care diagnostics in developing countries. Here, we combine paper-based microfluidic devices with responsive hydrogels to add an entire new class of functions to these versatile low-cost fluidic systems. The hydrogels serve as fluid reservoirs. In response to an external stimulus, e.g. an increase in temperature, the hydrogels collapse and release fluid into the structured paper substrate. In this way, chemicals that are either stored on the paper substrate or inside the hydrogel pads can be dissolved, premixed, and brought to reaction to fulfill specific analytic tasks. We demonstrate that multi-step sequences of chemical reactions can be implemented in a paper-based system and operated without the need for external precision pumps. We exemplify this technology by integrating an antibody-based E. coli test on a small and easy to use paper device.}, language = {en} }