@article{MachatschekHeuchelLendlein2021, author = {Machatschek, Rainhard Gabriel and Heuchel, Matthias and Lendlein, Andreas}, title = {Thin-layer studies on surface functionalization of polyetherimide}, series = {Journal of materials research : JMR / Materials Research Society}, volume = {37}, journal = {Journal of materials research : JMR / Materials Research Society}, number = {1}, publisher = {Springer}, address = {Berlin}, issn = {0884-2914}, doi = {10.1557/s43578-021-00339-7}, pages = {67 -- 76}, year = {2021}, abstract = {Among the high-performance and engineering polymers, polyimides and the closely related polyetherimide (PEI) stand out by their capability to react with nucleophiles under relatively mild conditions. By targeting the phthalimide groups in the chain backbone, post-functionalization offers a pathway to adjust surface properties such as hydrophilicity, solvent resistance, and porosity. Here, we use ultrathin PEI films on a Langmuir trough as a model system to investigate the surface functionalization with ethylene diamine and tetrakis(4-aminophenyl)porphyrin as multivalent nucleophiles. By means of AFM, Raman spectroscopy, and interfacial rheology, we show that hydrolysis enhances the chemical and mechanical stability of ultrathin films and allows for the formation of EDC/NHS-activated esters. Direct amidation of PEI was achieved in the presence of a Lewis acid catalyst, resulting in free amine groups rather than cross-linking. When comparing amidation with hydrolysis, we find a greater influence of the latter on material properties.}, language = {en} } @article{XieTaubert2011, author = {Xie, Zai-Lai and Taubert, Andreas}, title = {Thermomorphic behavior of the ionic liquids [C(4)mim][FeCl4] and [C(12)mim][FeCl4]}, series = {ChemPhysChem : a European journal of chemical physics and physical chemistry}, volume = {12}, journal = {ChemPhysChem : a European journal of chemical physics and physical chemistry}, number = {2}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1439-4235}, doi = {10.1002/cphc.201000808}, pages = {364 -- 368}, year = {2011}, abstract = {The iron-containing ionic liquids 1-butyl-3-methylimidazolium tetrachloroferrate(III) [C(4)mim][FeCl4] and 1-dodecyl-3-methylimidazolium tetrachloroferrate(III) [C(12)mim][FeCl4] exhibit a thermally induced demixing with water (thermomorphism). The phase separation temperature varies with IL weight fraction in water and can be tuned between 100 degrees C and room temperature. The reversible lower critical solution temperature (LCST) is only observed at IL weight fractions below ca. 35\% in water. UV/Vis, IR, and Raman spectroscopy along with elemental analysis prove that the yellow-brown liquid phase recovered after phase separation is the starting IL [C(4)mim][FeCl4] and [C(12)mim][FeCl4], respectively. Photometry and ICP-OES show that about 40\% of iron remains in the water phase upon phase separation. Although the process is thus not very efficient at the moment, the current approach is the first example of an LCST behavior of a metal-containing IL and therefore, although still inefficient, a prototype for catalyst removal or metal extraction.}, language = {en} } @article{SchmidtZiemannPentzienetal.2016, author = {Schmidt, Birgit Angelika and Ziemann, Martin Andreas and Pentzien, Simone and Gabsch, Toralf and Koch, Werner and Kr{\"u}ger, J{\"o}rg}, title = {Technical analysis of a Central Asian wall painting detached from a Buddhist cave temple on the northern Silk Road}, series = {Studies in Conservation}, volume = {61}, journal = {Studies in Conservation}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0039-3630}, doi = {10.1179/2047058414Y.0000000152}, pages = {113 -- 122}, year = {2016}, abstract = {A great number of Central Asian wall paintings, archeological materials, architectural fragments, and textiles, as well as painting fragments on silk and paper, make up the so called Turfan Collection at the Asian Art Museum in Berlin. The largest part of the collection comes from the Kucha region, a very important cultural center in the third to ninth centuries. Between 1902 and 1914, four German expeditions traveled along the northern Silk Road. During these expeditions, wall paintings were detached from their original settings in Buddhist cave complexes. This paper reports a technical study of a wall painting, existing in eight fragments, from the Buddhist cave no. 40 (Ritterhohle). Its original painted surface is soot blackened and largely illegible. Gruwedel, leader of the first and third expeditions, described the almost complete destruction of the rediscovered temple complex and evidence of fire damage. The aim of this case study is to identify the materials used for the wall paintings. Furthermore, soot deposits as well as materials from conservation interventions were of interest. Non-invasive analyses were preferred but a limited number of samples were taken to provide more precise information on the painting technique. By employing optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, micro X-ray fluorescence spectroscopy, X-ray diffraction analysis, and Raman spectroscopy, a layer sequence of earthen render, a ground layer made of gypsum, and a paint layer containing a variety of inorganic pigments were identified.}, language = {en} } @article{WunderKutzschbachHosseetal.2018, author = {Wunder, Bernd and Kutzschbach, Martin and Hosse, Luisa and Wilke, Franziska Daniela Helena and Schertl, Hans-Peter and Chopin, Christian}, title = {Synthetic B-[4]-bearing dumortierite and natural B-[4]-free magnesiodumortierite from the Dora-Maira Massif}, series = {European journal of mineralogy}, volume = {30}, journal = {European journal of mineralogy}, number = {3}, publisher = {Schweizerbart}, address = {Stuttgart}, issn = {0935-1221}, doi = {10.1127/ejm/2018/0030-2742}, pages = {471 -- 483}, year = {2018}, abstract = {Dumortierite was synthesized in piston-cylinder experiments at 2.5-4.0 GPa, 650-700 degrees C in the Al2O3 -B2O3-SiO2-H2O (ABSH) system. Electron-microprobe (EMP) analyses reveal significant boron-excess (up to 0.26 B-[4] per formula unit, pfu) and silicon-deficiency relative to the ideal anhydrous dumortierite stoichiometry Al7BSi3O18 . The EMP data in conjunction with results from single-crystal Raman spectroscopy and powder X-ray diffraction provide evidence that silicon at the tetrahedral site is replaced by excess boron via the substitution Si-[4] <--> B-[4] + H. The Raman spectrum of synthetic dumortierite in the frequency region 2000 4000 cm(-1) comprises eight bands, of which six are located at frequencies below 3400 cm(-1). This points to strong hydrogen bonding, most likely O2-H center dot center dot center dot O7 and O7-H center dot center dot center dot O2, arising from a high number of octahedral vacancies at the All site and substitution of trivalent Al3+ and B3+ for Si4+ at Si1 and Si2 sites, causing decreasing acceptor-donor distances and lower incident valence at the acceptor oxygen. Contrary to the synthetic high-pressure ABSH-dumortierite, magnesiodumortierite from the Dora-Maira Massif, which is assumed to have formed at similar conditions (2.5-3.0 GPa, 700 degrees C), does not show any B-excess. Tourmaline shows an analogous behaviour in that magnesium-rich (e.g., dravitic) tourmaline formed at high pressure shows no or only minor amounts of tetrahedral boron, whereas natural aluminum-rich tourmaline and synthetic olenitic tourmaline formed at high pressures can incorporate significant amounts of tetrahedral boron. Two mechanisms might account for this discrepancy: (i) Structural avoidance of Mg-[6]-(OR3+)-R-[4] configurations in magnesiodumortierite due to charge deficieny at the oxygens O2 and O7 and strong local distortion of M1 due to decreased O2-O7 bond length, and/or (ii) decreasing fluid mobility of boron in Al-rich systems at high pressures.}, language = {en} } @article{DemetriouPashalidisNicolaidesetal.2013, author = {Demetriou, Antri and Pashalidis, Ioannis and Nicolaides, Athanassios V. and Kumke, Michael Uwe}, title = {Surface mechanism of the boron adsorption on alumina in aqueous solutions}, series = {Desalination and water treatment : science and engineering}, volume = {51}, journal = {Desalination and water treatment : science and engineering}, number = {31-33}, publisher = {Taylor \& Francis Group}, address = {Philadelphia}, issn = {1944-3994}, doi = {10.1080/19443994.2013.764354}, pages = {6130 -- 6136}, year = {2013}, abstract = {The adsorption of boron (boric acid) from aqueous solutions on alumina has been investigated at pH 8.0, I=0.1M NaClO4, T=22 +/- 3 degrees C, and under normal atmospheric conditions. The characterization of the adsorbed species was performed by Raman spectroscopy and the spectroscopic speciation was assisted by theoretical DFT calculations. Evaluation of the spectroscopic data points to the formation of inner-sphere surface complexes and indicates the formation of two different types of adsorbed boron species. The theoretical calculations corroborate the spectroscopic data and indicate that at low boron concentration the monodentate surface species dominates, whereas increased boron concentration favors the formation of a bidentate surface species. Assuming low coverage, the conditional formation constant for the monodentate surface species has been evaluated to be log=4.1 +/- 0.1.}, language = {en} } @article{SarhanKoopmanPudelletal.2019, author = {Sarhan, Radwan Mohamed and Koopman, Wouter-Willem Adriaan and Pudell, Jan-Etienne and Stete, Felix and R{\"o}ssle, Matthias and Herzog, Marc and Schmitt, Clemens Nikolaus Zeno and Liebig, Ferenc and Koetz, Joachim and Bargheer, Matias}, title = {Scaling up nanoplasmon catalysis}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {123}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {14}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.8b12574}, pages = {9352 -- 9357}, year = {2019}, abstract = {Nanoscale heating by optical excitation of plasmonic nanoparticles offers a new perspective of controlling chemical reactions, where heat is not spatially uniform as in conventional macroscopic heating but strong temperature gradients exist around microscopic hot spots. In nanoplasmonics, metal particles act as a nanosource of light, heat, and energetic electrons driven by resonant excitation of their localized surface plasmon resonance. As an example of the coupling reaction of 4-nitrothiophenol into 4,4′-dimercaptoazobenzene, we show that besides the nanoscopic heat distribution at hot spots, the microscopic distribution of heat dictated by the spot size of the light focus also plays a crucial role in the design of plasmonic nanoreactors. Small sizes of laser spots enable high intensities to drive plasmon-assisted catalysis. This facilitates the observation of such reactions by surface-enhanced Raman scattering, but it challenges attempts to scale nanoplasmonic chemistry up to large areas, where the excess heat must be dissipated by one-dimensional heat transport.}, language = {en} } @article{SumpfMaiwaldMulleretal.2012, author = {Sumpf, Bernd and Maiwald, Martin and Muller, Andre and Ginolas, Arnim and Haeusler, Karl and Erbert, Goetz and Traenkle, Guenther}, title = {Reliable operation for 14 500 h of a wavelength-stabilized Diode Laser System on a Microoptical Bench at 671 nm}, series = {IEEE transactions on components, packaging and manufacturing technology}, volume = {2}, journal = {IEEE transactions on components, packaging and manufacturing technology}, number = {1}, publisher = {Inst. of Electr. and Electronics Engineers}, address = {Piscataway}, issn = {2156-3950}, doi = {10.1109/TCPMT.2011.2171342}, pages = {116 -- 121}, year = {2012}, abstract = {Reliability tests for wavelength-stabilized compact diode laser systems emitting at 671 nm are presented. The devices were mounted on microoptical benches with the dimensions of 13 mm x 4 mm. Reflecting Bragg gratings were used for wavelength stabilization and emission width narrowing. The reliability tests were performed at 25 degrees C and at an output power up to 10 mW per micrometer stripe width of the gain medium. Reliable operation could be demonstrated over a test time up to 14 500 h at an output power up to 1.0 W. Environmental tests using random vibrations with acceleration up to 29 g were performed without deterioration of the devices.}, language = {en} } @article{SchmaelzlinMoralejoGersondeetal.2018, author = {Schm{\"a}lzlin, Elmar Gerd and Moralejo, Benito and Gersonde, Ingo and Schleusener, Johannes and Darvin, Maxim E. and Thiede, Gisela and Roth, Martin M.}, title = {Nonscanning large-area Raman imaging for ex vivo/in vivo skin cancer discrimination}, series = {Journal of biomedical optics}, volume = {23}, journal = {Journal of biomedical optics}, number = {10}, publisher = {SPIE}, address = {Bellingham}, issn = {1083-3668}, doi = {10.1117/1.JBO.23.10.105001}, pages = {11}, year = {2018}, abstract = {Imaging Raman spectroscopy can be used to identify cancerous tissue. Traditionally, a step-by-step scanning of the sample is applied to generate a Raman image, which, however, is too slow for routine examination of patients. By transferring the technique of integral field spectroscopy (IFS) from astronomy to Raman imaging, it becomes possible to record entire Raman images quickly within a single exposure, without the need for a tedious scanning procedure. An IFS-based Raman imaging setup is presented, which is capable of measuring skin ex vivo or in vivo. It is demonstrated how Raman images of healthy and cancerous skin biopsies were recorded and analyzed. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.}, language = {en} } @article{GruenebergerSchmidtJahnetal.2016, author = {Gr{\"u}neberger, Anja Maria and Schmidt, Christian and Jahn, Sandro and Rhede, Dieter and Loges, Anselm and Wilke, Max}, title = {Interpretation of Raman spectra of the zircon-hafnon solid solution}, series = {European journal of mineralogy}, volume = {28}, journal = {European journal of mineralogy}, publisher = {Schweizerbart}, address = {Stuttgart}, issn = {0935-1221}, doi = {10.1127/ejm/2016/0028-2551}, pages = {721 -- 733}, year = {2016}, abstract = {Zircon (ZrSiO4), hafnon (HfSiO4) and five intermediate compositions were synthesized from a Pb silicate melt. The resulting crystals were 20-300 mu m in size and displayed sector and growth zoning. Raman spectra were acquired at locations in the sample for which preceding electron microprobe (EMP) analyses revealed sufficient compositional homogeneity. The dataset documents shifts of Raman bands with changing composition. In this study, bands that have previously not been reported were found for the intermediate compositions and for pure hafnon, in particular at wavenumbers less than 200 cm(-1). For these external modes, the dataset provides new insight into the compositional dependence of their frequencies. Density-functional theory calculations support the observations and are used for a detailed interpretation of the spectra. The pitfalls of the EMP analysis along the zircon-hafnon join are highlighted.}, language = {en} } @article{RiebeBeitzDoscheetal.2014, author = {Riebe, Daniel and Beitz, Toralf and Dosche, Carsten and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Raab, Volker and Raab, Corinna and Unverzagt, Matthias}, title = {High-resolution spectrometer using combined dispersive and interferometric wavelength separation for raman and laser-induced Breakdown Spectroscopy (LIBS)}, series = {Applied spectroscopy : an international journal of spectroscopy ; official publication of the Society for Applied Spectroscopy}, volume = {68}, journal = {Applied spectroscopy : an international journal of spectroscopy ; official publication of the Society for Applied Spectroscopy}, number = {9}, publisher = {Society for Applied Spectroscopy}, address = {Frederick}, issn = {0003-7028}, doi = {10.1366/13-07426}, pages = {1030 -- 1038}, year = {2014}, abstract = {In this paper the concept of a compact high-resolution spectrometer based on the combination of dispersive and interferometric elements is presented. Dispersive elements are used to spectrally resolve the light in one direction with coarse resolution (Delta lambda < 0.5 nm), while perpendicular to that direction an etalon provides high spectral resolution (Delta lambda < 50 pm). This concept for two-dimensional spectroscopy has been implemented for the wavelength range lambda = 350-650 nm. Appropriate algorithms for reconstructing spectra from the two-dimensional raw data and for wavelength calibration were established in an analysis software. Potential applications for this new spectrometer are Raman and laser-induced breakdown spectroscopy (LIBS). Resolutions down to 28 pm (routinely 54 pm) could be realized for these applications.}, language = {en} } @article{ErmeydanCabaneMasicetal.2012, author = {Ermeydan, Mahmut Ali and Cabane, Etienne and Masic, Admir and Koetz, Joachim and Burgert, Ingo}, title = {Flavonoid insertion into cell walls improves wood properties}, series = {ACS applied materials \& interfaces}, volume = {4}, journal = {ACS applied materials \& interfaces}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/am301266k}, pages = {5782 -- 5789}, year = {2012}, abstract = {Wood has an excellent mechanical performance, but wider utilization of this renewable resource as an engineering material is limited by unfavorable properties such as low dimensional stability upon moisture changes and a low durability. However, some wood species are known to produce a wood of higher quality by inserting mainly phenolic substances in the already formed cell walls a process so-called heartwood formation. In the present study, we used the heartwood formation in black locust (Robinia pseudoacacia) as a source of bioinspiration and transferred principles of the modification in order to improve spruce wood properties (Picea abies) by a chemical treatment with commercially available flavonoids. We were able to effectively insert hydrophobic flavonoids in the cell wall after a tosylation treatment for activation. The chemical treatment reduced the water uptake of the wood cell walls and increased the dimensional stability of the bulk spruce wood. Further analysis of the chemical interaction of the flavonoid with the structural cell wall components revealed the basic principle of this bioinspired modification. Contrary to established modification treatments, which mainly address the hydroxyl groups of the carbohydrates with hydrophilic substances, the hydrophobic flavonoids are effective by a physical bulking in the cell wall most probably stabilized by pi-pi interactions. A biomimetic transfer of the underlying principle may lead to alternative cell wall modification procedures and improve the performance of wood as an engineering material.}, language = {en} } @article{KleinDarvinMeinkeetal.2013, author = {Klein, Julia and Darvin, Maxim E. and Meinke, Martina C. and Schweigert, Florian J. and M{\"u}ller, Kerstin E. and Lademann, J{\"u}rgen}, title = {Analyses of the correlation between dermal and blood carotenoids in female cattle by optical methods}, series = {Journal of biomedical optics}, volume = {18}, journal = {Journal of biomedical optics}, number = {6}, publisher = {SPIE}, address = {Bellingham}, issn = {1083-3668}, doi = {10.1117/1.JBO.18.6.061219}, pages = {6}, year = {2013}, abstract = {Herd health programs for the maintenance of welfare and productivity in cattle need efficient tools for monitoring the health of individual animals. Recent reports demonstrate that the oxidative status is related to various stress conditions in dairy cows. Biomarkers, among other carotenoids, could serve as indicators of stress originating from the environment (e.g., heat stress or sun radiation) or from the animal itself (e.g., disease). To date, only invasive in vitro tests are available to assess the oxidative status in cattle. The present study compares the results of optical noninvasive in vivo measurements of dermal carotenoids in cattle udder skin using an LED-based miniaturized spectroscopic system (MSS) with those obtained by photometric analysis of beta carotene in whole blood samples using a portable device. Correlations between the concentrations of dermal and blood carotenoids were calculated under consideration of the nutritional status of the animals. Significant correlation (R = 0.86) was found for cattle with a moderate to obese body condition. Thus, the blood and skin concentrations of the marker substance beta carotene are comparable under stable stress conditions of the cattle. This demonstrates that the MSS is suitable for noninvasive assessment of dermal carotenoid concentrations in cattle.}, language = {en} }