@article{AdemMbavengKueteetal.2019,
  author    = {Adem, Fozia A. and Mbaveng, Armelle T. and Kuete, Victor and Heydenreich, Matthias and Ndakala, Albert and Irungu, Beatrice and Yenesew, Abiy and Efferth, Thomas},
  title     = {Cytotoxicity of isoflavones and biflavonoids from Ormocarpum kirkii towards multi-factorial drug resistant cancer},
  series = {Phytomedicine : international journal of phytotherapy and phytopharmacology},
  volume    = {58},
  journal   = {Phytomedicine : international journal of phytotherapy and phytopharmacology},
  publisher = {Elsevier},
  address   = {M{\"u}nchen},
  issn      = {0944-7113},
  doi       = {10.1016/j.phymed.2019.152853},
  pages     = {10},
  year      = {2019},
  abstract  = {Background: While incidences of cancer are continuously increasing, drug resistance of malignant cells is observed towards almost all pharmaceuticals. Several isoflavonoids and flavonoids are known for their cytotoxicity towards various cancer cells. Methods: The cytotoxicity of compounds was determined based on the resazurin reduction assay. Caspases activation was evaluated using the caspase-Glo assay. Flow cytometry was used to analyze the cell cycle (propodium iodide (PI) staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP) (JC-1) and reactive oxygen species (ROS) (H2DCFH-DA). CCRF-CEM leukemia cells were used as model cells for mechanistic studies. Results: Compounds 1, 2 and 4 displayed IC50 values below 20 mu M towards CCRF-CEM and CEM/ADR5000 leukemia cells, and were further tested towards a panel of 7 carcinoma cells. The IC50 values of the compounds against carcinoma cells varied from 16.90 mu M (in resistant U87MG.Delta EGFR glioblastoma cells) to 48.67 mu M (against HepG2 hepatocarcinoma cells) for 1, from 7.85 mu M (in U87MG.Delta EGFR cells) to 14.44 mu M (in resistant MDA-MB231/BCRP breast adenocarcinoma cells) for 2, from 4.96 mu M (towards U87MG.Delta EGFRcells) to 7.76 mu M (against MDA-MB231/BCRP cells) for 4, and from 0.07 mu M (against MDA-MB231 cells) to 2.15 mu M (against HepG2 cells) for doxorubicin. Compounds 2 and 4 induced apoptosis in CCRF-CEM cells mediated by MMP alteration and increased ROS production. Conclusion: The present report indicates that isoflavones and biflavonoids from Ormocarpum kirkii are cytotoxic compounds with the potential of being exploited in cancer chemotherapy. Compounds 2 and 4 deserve further studies to develop new anticancer drugs to fight sensitive and resistant cancer cell lines.},
  language  = {en}
}
@article{AlNakeebKochovskiLietal.2019,
  author    = {Al Nakeeb, Noah and Kochovski, Zdravko and Li, Tingting and Zhang, Youjia and Lu, Yan and Schmidt, Bernhard V. K. J.},
  title     = {Poly(ethylene glycol) brush-b-poly(N-vinylpyrrolidone)-based double hydrophilic block copolymer particles crosslinked via crystalline alpha-cyclodextrin domains},
  series = {RSC Advances},
  volume    = {9},
  journal   = {RSC Advances},
  number    = {9},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/c8ra10672j},
  pages     = {4993 -- 5001},
  year      = {2019},
  abstract  = {Self-assembly of block copolymers is a significant area of polymer science. The self-assembly of completely water-soluble block copolymers is of particular interest, albeit a challenging task. In the present work the self-assembly of a linear-brush architecture block copolymer, namely poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) (PVP-b-POEGMA), in water is studied. Moreover, the assembled structures are crosslinked via alpha-CD host/guest complexation in a supramolecular way. The crosslinking shifts the equilibrium toward aggregate formation without switching off the dynamic equilibrium of double hydrophilic block copolymer (DHBC). As a consequence, the self-assembly efficiency is improved without extinguishing the unique DHBC self-assembly behavior. In addition, decrosslinking could be induced without a change in concentration by adding a competing complexation agent for alpha-CD. The self-assembly behavior was followed by DLS measurement, while the presence of the particles could be observed via cryo-TEM before and after crosslinking.},
  language  = {en}
}
@article{AloniPerovicWeitmanetal.2019,
  author    = {Aloni, Sapir Shekef and Perovic, Milena and Weitman, Michal and Cohen, Reut and Oschatz, Martin and Mastai, Yitzhak},
  title     = {Amino acid-based ionic liquids as precursors for the synthesis of chiral nanoporous carbons},
  series = {Nanoscale Advances},
  volume    = {1},
  journal   = {Nanoscale Advances},
  number    = {12},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2516-0230},
  doi       = {10.1039/c9na00520j},
  pages     = {4981 -- 4988},
  year      = {2019},
  abstract  = {The synthesis of chiral nanoporous carbons based on chiral ionic liquids (CILs) of amino acids as precursors is described. Such unique precursors for the carbonization of CILs yield chiral carbonaceous materials with high surface area (approximate to 620 m(2) g(-1)). The enantioselectivities of the porous carbons are examined by advanced techniques such as selective adsorption of enantiomers using cyclic voltammetry, isothermal titration calorimetry, and mass spectrometry. These techniques demonstrate the chiral nature and high enantioselectivity of the chiral carbon materials. Overall, we believe that the novel approach presented here can contribute significantly to the development of new chiral carbon materials that will find important applications in chiral chemistry, such as in chiral catalysis and separation and in chiral sensors. From a scientific point of view, the approach and results reported here can significantly deepen our understanding of chirality at the nanoscale and of the structure and nature of chiral nonporous materials and surfaces.},
  language  = {en}
}
@article{AlrefaiMondalWrucketal.2019,
  author    = {Alrefai, Anas and Mondal, Suvendu Sekhar and Wruck, Alexander and Kelling, Alexandra and Schilde, Uwe and Brandt, Philipp and Janiak, Christoph and Schoenfeld, Sophie and Weber, Birgit and Rybakowski, Lawrence and Herrman, Carmen and Brennenstuhl, Katlen and Eidner, Sascha and Kumke, Michael Uwe and Behrens, Karsten and G{\"u}nter, Christina and M{\"u}ller, Holger and Holdt, Hans-J{\"u}rgen},
  title     = {Hydrogen-bonded supramolecular metal-imidazolate frameworks: gas sorption, magnetic and UV/Vis spectroscopic properties},
  series = {Journal of Inclusion Phenomena and Macrocyclic Chemistry},
  volume    = {94},
  journal   = {Journal of Inclusion Phenomena and Macrocyclic Chemistry},
  number    = {3-4},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {1388-3127},
  doi       = {10.1007/s10847-019-00926-6},
  pages     = {155 -- 165},
  year      = {2019},
  abstract  = {By varying reaction parameters for the syntheses of the hydrogen-bonded metal-imidazolate frameworks (HIF) HIF-1 and HIF-2 (featuring 14 Zn and 14 Co atoms, respectively) to increase their yields and crystallinity, we found that HIF-1 is generated in two different frameworks, named as HIF-1a and HIF-1b. HIF-1b is isostructural to HIF-2. We determined the gas sorption and magnetic properties of HIF-2. In comparison to HIF-1a (Brunauer-Emmett-Teller (BET) surface area of 471m(2) g(-1)), HIF-2 possesses overall very low gas sorption uptake capacities [BET(CO2) surface area=85m(2) g(-1)]. Variable temperature magnetic susceptibility measurement of HIF-2 showed antiferromagnetic exchange interactions between the cobalt(II) high-spin centres at lower temperature. Theoretical analysis by density functional theory confirmed this finding. The UV/Vis-reflection spectra of HIF-1 (mixture of HIF-1a and b), HIF-2 and HIF-3 (with 14 Cd atoms) were measured and showed a characteristic absorption band centered at 340nm, which was indicative for differences in the imidazolate framework.},
  language  = {en}
}
@article{BaldSchuermannEbeletal.2019,
  author    = {Bald, Ilko and Sch{\"u}rmann, Robin Mathis and Ebel, Kenny and Nicolas, Christophe and Milosavljevic, Aleksandar R.},
  title     = {Role of valence band states and plasmonic enhancement in electron-transfer-induced transformation of nitrothiophenol},
  series = {The Journal of Physical Chemistry Letters},
  volume    = {10},
  journal   = {The Journal of Physical Chemistry Letters},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.9b00848},
  pages     = {3153 -- 3158},
  year      = {2019},
  abstract  = {Hot-electron-induced reactions are more and more recognized as a critical and ubiquitous reaction in heterogeneous catalysis. However, the kinetics of these reactions is still poorly understood, which is also due to the complexity of plasmonic nanostructures. We determined the reaction rates of the hot-electron-mediated reaction of 4-nitrothiophenol (NTP) on gold nanoparticles (AuNPs) using fractal kinetics as a function of the laser wavelength and compared them with the plasmonic enhancement of the system. The reaction rates can be only partially explained by the plasmonic response of the NPs. Hence, synchrotron X-ray photoelectron spectroscopy (XPS) measurements of isolated NTP-capped AuNP clusters have been performed for the first time. In this way, it was possible to determine the work function and the accessible valence band states of the NP systems. The results show that besides the plasmonic enhancement, the reaction rates are strongly influenced by the local density of the available electronic states of the system.},
  language  = {en}
}
@article{BalderasValadezSchuermannPacholski2019,
  author    = {Balderas-Valadez, Ruth Fabiola and Sch{\"u}rmann, Robin Mathis and Pacholski, Claudia},
  title     = {One Spot-Two Sensors: Porous Silicon Interferometers in Combination With Gold Nanostructures Showing Localized Surface Plasmon Resonance},
  series = {Frontiers in chemistry},
  volume    = {7},
  journal   = {Frontiers in chemistry},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {2296-2646},
  doi       = {10.3389/fchem.2019.00593},
  pages     = {12},
  year      = {2019},
  abstract  = {Sensors composed of a porous silicon monolayer covered with a film of nanostructured gold layer, which provide two optical signal transduction methods, are fabricated and thoroughly characterized concerning their sensing performance. For this purpose, silicon substrates were electrochemically etched in order to obtain porous silicon monolayers, which were subsequently immersed in gold salt solution facilitating the formation of a porous gold nanoparticle layer on top of the porous silicon. The deposition process was monitored by reflectance spectroscopy, and the appearance of a dip in the interference pattern of the porous silicon layer was observed. This dip can be assigned to the absorption of light by the deposited gold nanostructures leading to localized surface plasmon resonance. The bulk sensitivity of these sensors was determined by recording reflectance spectra in media having different refractive indices and compared to sensors exclusively based on porous silicon or gold nanostructures. A thorough analysis of resulting shifts of the different optical signals in the reflectance spectra on the wavelength scale indicated that the optical response of the porous silicon sensor is not influenced by the presence of a gold nanostructure on top. Moreover, the adsorption of thiol-terminated polystyrene to the sensor surface was solely detected by changes in the position of the dip in the reflectance spectrum, which is assigned to localized surface plasmon resonance in the gold nanostructures. The interference pattern resulting from the porous silicon layer is not shifted to longer wavelengths by the adsorption indicating the independence of the optical response of the two nanostructures, namely porous silicon and nanostructured gold layer, to refractive index changes and pointing to the successful realization of two sensors in one spot.},
  language  = {en}
}
@article{BalkBehlLendlein2019,
  author    = {Balk, Maria and Behl, Marc and Lendlein, Andreas},
  title     = {Quadruple-shape hydrogels},
  series = {Smart materials and structures},
  volume    = {28},
  journal   = {Smart materials and structures},
  number    = {5},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0964-1726},
  doi       = {10.1088/1361-665X/ab0e91},
  pages     = {10},
  year      = {2019},
  abstract  = {The capability of directed movements by two subsequent shape changes could be implemented in shape-memory hydrogels by incorporation of two types of crystallizable side chains While in non-swollen polymer networks even more directed movements could be realized, the creation of multi-shape hydrogels is still a challenge. We hypothesize that a quadruple-shape effect in hydrogels can be realized, when a swelling capacity almost independent of temperature is generated, whereby directed movements could be enabled, which are not related to swelling. In this case, entropy elastic recovery could be realized by hydrophilic segments and the fixation of different macroscopic shapes by means of three semi-crystalline side chains generating temporary crosslinks. Monomethacrylated semi-crystalline oligomers were connected as side chains in a hydrophilic polymer network via radical copolymerization. Computer assisted modelling was utilized to design a demonstrator capable of complex shape shifts by creating a casting mold via 3D printing from polyvinyl alcohol. The demonstrator was obtained after copolymerization of polymer network forming components within the mold, which was subsequently dissolved in water. A thermally-induced quadruple-shape effect was realized after equilibrium swelling of the polymer network in water. Three directed movements were successfully obtained when the temperature was continuously increased from 5 degrees C to 90 degrees C with a recovery ratio of the original shape above 90\%. Hence, a thermally-induced quadruple-shape effect as new record for hydrogels was realized. Here, the temperature range for the multi-shape effect was limited by water as swelling media (0 degrees C-100 degrees C), simultaneously distinctly separated thermal transitions were required, and the overall elasticity indispensable for successive deformations was reduced as result of partially chain segment orientation induced by swelling in water. Conclusively the challenges for penta- or hexa-shape gels are the design of systems enabling higher elastic deformability and covering a larger temperature range by switching to a different solvent.},
  language  = {en}
}
@article{BalkBehlLendlein2019,
  author    = {Balk, Maria and Behl, Marc and Lendlein, Andreas},
  title     = {Hydrolytic Degradation of Actuators Based on Copolymer Networks From Oligo(epsilon-caprolactone) Dimethacrylate and n-Butyl Acrylate},
  series = {MRS advances},
  volume    = {4},
  journal   = {MRS advances},
  number    = {21},
  publisher = {Cambridge Univ. Press},
  address   = {New York},
  issn      = {2059-8521},
  doi       = {10.1557/adv.2019.202},
  pages     = {1193 -- 1205},
  year      = {2019},
  abstract  = {Shape-memory polymer actuators often contain crystallizable polyester segments. Here, the influence of accelerated hydrolytic degradation on the actuation performance in copolymer networks based on oligo(epsilon-caprolactone) dimethacrylate (OCL) and n-butyl acrylate is studied The semi-crystalline OCL was utilized as crosslinker with molecular weights of 2.3 and 15.2 kg.mol(-1) (ratio: 1:1 wt\%) and n-butyl acrylate (25 wt\% relative to OCL content) acted as softening agent creating the polymer main chain segments within the network architecture. The copolymer networks were programmed by 50\% elongation and were degraded by means of alkaline hydrolysis utilizing sodium hydroxide solution (pH = 13). Experiments were performed in the range of the broad melting range of the actuators at 40 degrees C. The degradation of test specimen was monitored by the sample mass, which was reduced by 25 wt\% within 105 d .45 degradation products, fragments of OCL with molecular masses ranging from 400 to 50.000 g.mol(-1) could be detected by NMR spectroscopy and GPC measurements. The cleavage of ester groups included in OCL segments resulted in a decrease of the melting temperature (T-m) related to the actuator domains (amorphous at the temperature of degradation) and simultaneously, the T-m associated to the skeleton domain was increased (semi-crystalline at the temperature of degradation). The alkaline hydrolysis decreased the polymer chain orientation of OCL domains until a random alignment of crystalline domains was obtained. This result was confirmed by cyclic thermomechanical actuation tests. The performance of directed movements decreased almost linearly as function of degradation time resulting in the loss of functionality when the orientation of polymer chains disappeared. Here, actuators were able to provide reversible movements until 91 d when the accelerated bulk degradation procedure using alkaline hydrolysis (pH = 13) was applied. Accordingly, a lifetime of more than one year can be guaranteed under physiological conditions (pH = 7.4) when, e.g., artificial muscles for biomimetic robots as potential application for these kind of shape-memory polymer actuators will be addressed.},
  language  = {en}
}
@article{BedurkeKlamrothKrauseetal.2019,
  author    = {Bedurke, Florian and Klamroth, Tillmann and Krause, Pascal and Saalfrank, Peter},
  title     = {Discriminating organic isomers by high harmonic generation},
  series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  volume    = {150},
  journal   = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  number    = {23},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0021-9606},
  doi       = {10.1063/1.5096473},
  pages     = {10},
  year      = {2019},
  abstract  = {High Harmonic Generation (HHG) is a nonlinear optical process that provides a tunable source for high-energy photons and ultrashort laser pulses. Recent experiments demonstrated that HHG spectroscopy may also be used as an analytical tool to discriminate between randomly oriented configurational isomers of polyatomic organic molecules, namely, between the cis- and trans-forms of 1,2-dichloroethene (DCE) [M. C. H. Wong et al., Phys. Rev. A 84, 051403 (2011)]. Here, we suggest as an economic and at the same time a reasonably accurate method to compute HHG spectra for polyatomic species, Time-Dependent Configuration Interaction Singles (TD-CIS) theory in combination with extended atomic orbital bases and different models to account for ionization losses. The HHG spectra are computed for aligned and unaligned cis- and trans-DCE. For the unaligned case, a coherent averaging over possible rotational orientations is introduced. Furthermore, using TD-CIS, possible differences between the HHG spectra of cis- and trans-DCE are studied. For aligned molecules, spectral differences between cis and trans emerge, which can be related to their different point group symmetries. For unaligned, randomly oriented molecules, we also find distinct HHG spectra in partial agreement with experiment. In addition to HHG response in the frequency space, we compute time-frequency HHG spectra to gain insight into which harmonics are emitted at which time. Further differences between the two isomers emerge, suggesting time-frequency HHG as another tool to discriminate configurational isomers.},
  language  = {en}
}
@article{BehrendtHessLehmannetal.2019,
  author    = {Behrendt, Felix Nicolas and Hess, Andreas and Lehmann, Max and Schmidt, Bernd and Schlaad, Helmut},
  title     = {Polymerization of cystine-derived monomers},
  series = {Polymer Chemistry},
  volume    = {10},
  journal   = {Polymer Chemistry},
  number    = {13},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1759-9954},
  doi       = {10.1039/c9py00118b},
  pages     = {1636 -- 1641},
  year      = {2019},
  abstract  = {Cystine was used as a platform chemical to prepare cyclic and acyclic monomers for entropy-driven ringopening polymerization (ED-ROMP) via olefin or disulfide metathesis and for step-growth polymerization. The olefin ED-ROMP of an olefin/disulfide containing 16-atom macrocycle using the 3rd generation Grubbs catalyst was examined in greater detail. Kinetic studies revealed that the catalyst turned inactive during the polymerization, which limited the achievable (apparent) polymer molar mass to similar to 70 kg mol(-1). Such limitation could be overcome with the disulfide ED-ROMP of the same macrocycle to yield polymers with molar masses of up to 180 kg mol(-1). The step-growth polymerizations of acyclic diene and dithiol monomers via olefin metathesis or oxidation were far less effective and yielded just low molar mass polymers or oligomers; photopolymerization of a thiol-ene monomer produced a polyester with a molar mass of 35 kg mol(-1).},
  language  = {en}
}
@article{BhuvaneshMachatschekLysyakovaetal.2019,
  author    = {Bhuvanesh, Thanga and Machatschek, Rainhard Gabriel and Lysyakova, Liudmila and Kratz, Karl and Schulz, Burkhard and Ma, Nan and Lendlein, Andreas},
  title     = {Collagen type-IV Langmuir and Langmuir-Schafer layers as model biointerfaces to direct stem cell adhesion},
  series = {Biomedical materials : materials for tissue engineering and regenerative medicine},
  volume    = {14},
  journal   = {Biomedical materials : materials for tissue engineering and regenerative medicine},
  number    = {2},
  publisher = {Inst. of Physics Publ.},
  address   = {Bristol},
  issn      = {1748-6041},
  doi       = {10.1088/1748-605X/aaf464},
  pages     = {17},
  year      = {2019},
  abstract  = {In biomaterial development, the design of material surfaces that mimic the extra-cellular matrix (ECM) in order to achieve favorable cellular instruction is rather challenging. Collagen-type IV (Col-IV), the major scaffolding component of Basement Membranes (BM), a specialized ECM with multiple biological functions, has the propensity to form networks by self-assembly and supports adhesion of cells such as endothelial cells or stem cells. The preparation of biomimetic Col-IV network-like layers to direct cell responses is difficult. We hypothesize that the morphology of the layer, and especially the density of the available adhesion sites, regulates the cellular adhesion to the layer. The Langmuir monolayer technique allows for preparation of thin layers with precisely controlled packing density at the air-water (A-W) interface. Transferring these layers onto cell culture substrates using the Langmuir-Schafer (LS) technique should therefore provide a pathway for preparation of BM mimicking layers with controlled cell adherence properties. In situ characterization using ellipsometry and polarization modulation-infrared reflection absorption spectroscopy of Col-IV layer during compression at the A-W interface reveal that there is linear increase of surface molecule concentration with negligible orientational changes up to a surface pressure of 25 mN m(-1). Smooth and homogeneous Col-IV network-like layers are successfully transferred by LS method at 15 mN m(-1) onto poly(ethylene terephthalate) (PET), which is a common substrate for cell culture. In contrast, the organization of Col-IV on PET prepared by the traditionally employed solution deposition method results in rather inhomogeneous layers with the appearance of aggregates and multilayers. Progressive increase in the number of early adherent mesenchymal stem cells (MSCs) after 24 h by controlling the areal Col-IV density by LS transfer at 10, 15 and 20 mN m(-1) on PET is shown. The LS method offers the possibility to control protein characteristics on biomaterial surfaces such as molecular density and thereby, modulate cell responses.},
  language  = {en}
}
@article{BouaklineFischerSaalfrank2019,
  author    = {Bouakline, Foudhil and Fischer, E. W. and Saalfrank, Peter},
  title     = {A quantum-mechanical tier model for phonon-driven vibrational relaxation dynamics of adsorbates at surfaces},
  series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  volume    = {150},
  journal   = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  number    = {24},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0021-9606},
  doi       = {10.1063/1.5099902},
  pages     = {14},
  year      = {2019},
  abstract  = {We present a quantum-mechanical tier model for vibrational relaxation of low-lying excited states of an adsorbate vibrational mode (system), coupled to surface phonons (bath), at zero temperature. The tier model, widely used in studies of intramolecular vibrational energy redistribution in polyatomics, is adapted here to adsorbate-surface systems with the help of an embedded cluster approach, using orthogonal coordinates for the system and bath modes, and a phononic expansion of their interaction. The key idea of the model is to organize the system-bath zeroth-order vibrational space into a hierarchical structure of vibrational tiers and keep therein only vibrational states that are sequentially generated from the system-bath initial vibrational state. Each tier is generated from the previous one by means of a successor operator, derived from the system-bath interaction Hamiltonian. This sequential procedure leads to a drastic reduction of the dimension of the system-bath vibrational space. We notably show that for harmonic vibrational motion of the system and linear system-bath couplings in the system coordinate, the dimension of the tier-model vibrational basis scales as similar to N-lxv. Here, N is the number of bath modes, l is the highest-order of the phononic expansion, and l is the size of the system vibrational basis. This polynomial scaling is computationally far superior to the exponential scaling of the original zeroth-order vibrational basis, similar to M-N, with M being the number of basis functions per bath mode. In addition, since each tier is coupled only to its adjacent neighbors, the matrix representation of the system-bath Hamiltonian in this new vibrational basis has a symmetric block-tridiagonal form, with each block being very sparse. This favors the combination of the tier-model with iterative Krylov techniques, such as the Lanczos algorithm, to solve the time-dependent Schrodinger equation for the full Hamiltonian. To illustrate the method, we study vibrational relaxation of a D-Si bending mode, coupled via two-and (mainly) one-phonon interactions to a fully D-covered Si(100)-(2 x 1) surface, using a recent first-principles system-bath Hamiltonian. The results of the tier model are compared with those obtained by the Lindblad formalism of the reduced density matrix. We find that the tier model provides much more information and insight into mechanisms of vibration-phonon couplings at surfaces, and gives more reliable estimates of the adsorbate vibrational lifetimes. Moreover, the tier model might also serve as a benchmark for other approximate quantum-dynamics methods, such as multiconfiguration wavefunction approaches. Published under license by AIP Publishing.},
  language  = {en}
}
@article{BreternitzLehmannBarnettetal.2019,
  author    = {Breternitz, Joachim and Lehmann, Frederike and Barnett, Sarah A. and Nowell, Harriott and Schorr, Susan},
  title     = {Role of the Iodide-methylammonium interaction in the ferroelectricity of CH3NH3PbI3},
  series = {Angewandte Chemie - international edition},
  volume    = {59},
  journal   = {Angewandte Chemie - international edition},
  number    = {1},
  publisher = {John Wiley \& Sons, Inc.},
  address   = {New Jersey},
  pages     = {5},
  year      = {2019},
  abstract  = {Excellent conversion efficiencies of over 20\% and facile cell production have placed hybrid perovskites at the forefront of novel solar cell materials, with CH3NH3PbI3 being an archetypal compound. The question why CH3NH3PbI3 has such extraordinary characteristics, particularly a very efficient power conversion from absorbed light to electrical power, is hotly debated, with ferroelectricity being a promising candidate. This does, however, require the crystal structure to be non-centrosymmetric and we herein present crystallographic evidence as to how the symmetry breaking occurs on a crystallographic and, therefore, long-range level. Although the molecular cation CH3NH3+ is intrinsically polar, it is heavily disordered and this cannot be the sole reason for the ferroelectricity. We show that it, nonetheless, plays an important role, as it distorts the neighboring iodide positions from their centrosymmetric positions.},
  language  = {en}
}
@article{BrunacciNeffeWischkeetal.2019,
  author    = {Brunacci, Nadia and Neffe, Axel T. and Wischke, Christian and Naolou, Toufik and N{\"o}chel, Ulrich and Lendlein, Andreas},
  title     = {Oligodepsipeptide (nano)carriers},
  series = {Journal of controlled release},
  volume    = {301},
  journal   = {Journal of controlled release},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0168-3659},
  doi       = {10.1016/j.jconrel.2019.03.004},
  pages     = {146 -- 156},
  year      = {2019},
  abstract  = {High drug loads of nanoparticles are essential to efficiently provide a desired dosage in the required timeframe, however, these conditions may not be reached with so far established degradable matrices. Our conceptual approach for increasing the drug load is based on strengthening the affinity between drug and matrix in combination with stabilizing drug-matrix-hybrids through strong intermolecular matrix interactions. Here, a method for designing such complex drug-matrix hybrids is introduced employing computational methods (molecular dynamics and docking) as well as experimental studies (affinity, drug loading and distribution, drug release from films and nanoparticles). As model system, dexamethasone (DXM), relevant for the treatment of inflammatory diseases, in combination with poly[(rac-lactide)-co-glycolide] (PLGA) as standard degradable matrix or oligo[(3-(S)-sec-butyl) morpholine-2,5-dione] diol (OBMD) as matrix with hypothesized stronger interaction with DXM were investigated. Docking studies predicted higher affinity of DXM to OBMD than PLGA and displayed amide bond participation in hydrogen bonding with OBMD. Experimental investigations on films and nanoparticles, i.e. matrices of different shapes and sizes, confirmed this phenomenon as shown e.g. by a similar to 10 times higher solid state solubility of DXM in OBMD than in PLGA. DXM-loaded particles of similar to 150 nm prepared by nanoprecipitation in aqueous environment had a drug loading (DL) up to 16 times higher when employing OBMD as matrix compared to PLGA carriers due to enhanced drug retention in the OBMD phase. Importantly, drug relase periods were not altered as the release from films and particles was mainly ruled by the diffusion length as well as matrix degradation rather than the matrix type, which can be assigned to water diffusing into the matrix and breaking up of drug-matrix hydrogen bonds. Overall, the presented design and fabrication scheme showed predictive power and might universally enable the screening of drug/matrix interactions particularly to expand the oligodepsipeptide platform technology, e.g. by varying the depsipeptide side chains, for drug carrier and release systems.},
  language  = {en}
}
@article{BruunHille2019,
  author    = {Bruun, Kristina and Hille, Carsten},
  title     = {Study on intracellular delivery of liposome encapsulated quantum dots using advanced fluorescence microscopy},
  series = {Scientific reports},
  volume    = {9},
  journal   = {Scientific reports},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-019-46732-5},
  pages     = {15},
  year      = {2019},
  abstract  = {Quantum dots increasingly gain popularity for in vivo applications. However, their delivery and accumulation into cells can be challenging and there is still lack of detailed information. Thereby, the application of advanced fluorescence techniques can expand the portfolio of useful parameters for a more comprehensive evaluation. Here, we encapsulated hydrophilic quantum dots into liposomes for studying cellular uptake of these so-called lipodots into living cells. First, we investigated photophysical properties of free quantum dots and lipodots observing changes in the fluorescence decay time and translational diffusion behaviour. In comparison to empty liposomes, lipodots exhibited an altered zeta potential, whereas their hydrodynamic size did not change. Fluorescence lifetime imaging microscopy (FLIM) and fluorescence correlation spectroscopy (FCS), both combined with two-photon excitation (2P), were used to investigate the interaction behaviour of lipodots with an insect epithelial tissue. In contrast to the application of free quantum dots, their successful delivery into the cytosol of salivary gland duct cells could be observed when applying lipodots. Lipodots with different lipid compositions and surface charges did not result in considerable differences in the intracellular labelling pattern, luminescence decay time and diffusion behaviour. However, quantum dot degradation after intracellular accumulation could be assumed from reduced luminescence decay times and blue-shifted luminescence signals. In addition to single diffusing quantum dots, possible intracellular clustering of quantum dots could be assumed from increased diffusion times. Thus, by using a simple and manageable liposome carrier system, 2P-FLIM and 2P-FCS recording protocols could be tested, which are promising for investigating the fate of quantum dots during cellular interaction.},
  language  = {en}
}
@article{BurekDenglerEmmerlingetal.2019,
  author    = {Burek, Katja and Dengler, Joachim and Emmerling, Franziska and Feldmann, Ines and Kumke, Michael Uwe and Stroh, Julia},
  title     = {Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems},
  series = {ChemistryOpen},
  volume    = {8},
  journal   = {ChemistryOpen},
  number    = {12},
  publisher = {Wiley-VCH-Verl.},
  address   = {Weinheim},
  issn      = {2191-1363},
  doi       = {10.1002/open.201900249},
  pages     = {1441 -- 1452},
  year      = {2019},
  abstract  = {The hydration process of Portland cement in a cementitious system is crucial for development of the high-quality cement-based construction material. Complementary experiments of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and time-resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time-dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium-silicate-hydrates (C-S-H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C-S-H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process.},
  language  = {en}
}
@article{BuecheleChaoOstermannetal.2019,
  author    = {B{\"u}chele, Dominique and Chao, Madlen and Ostermann, Markus and Leenen, Matthias and Bald, Ilko},
  title     = {Multivariate chemometrics as a key tool for prediction of K and Fe in a diverse German agricultural soil-set using EDXRF},
  series = {Scientific Reports},
  volume    = {9},
  journal   = {Scientific Reports},
  publisher = {Macmillan Publishers Limited, part of Springer Nature},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-019-53426-5},
  pages     = {11},
  year      = {2019},
  abstract  = {Within the framework of precision agriculture, the determination of various soil properties is moving into focus, especially the demand for sensors suitable for in-situ measurements. Energy-dispersive X-ray fluorescence (EDXRF) can be a powerful tool for this purpose. In this study a huge diverse soil set (n = 598) from 12 different study sites in Germany was analysed with EDXRF. First, a principal component analysis (PCA) was performed to identify possible similarities among the sample set. Clustering was observed within the four texture classes clay, loam, silt and sand, as clay samples contain high and sandy soils low iron mass fractions. Furthermore, the potential of uni- and multivariate data evaluation with partial least squares regression (PLSR) was assessed for accurate determination of nutrients in German agricultural samples using two calibration sample sets. Potassium and iron were chosen for testing the performance of both models. Prediction of these nutrients in 598 German soil samples with EDXRF was more accurate using PLSR which is confirmed by a better overall averaged deviation and PLSR should therefore be preferred.},
  language  = {en}
}
@article{daSilvaVarellaJonesetal.2019,
  author    = {da Silva, Filipe Ferreira and Varella, Marcio T. do N. and Jones, Nykola C. and Hoffmann, Soren Vronning and Denifl, Stephan and Bald, Ilko and Kopyra, Janina},
  title     = {Electron-Induced Reactions in 3-Bromopyruvic Acid},
  series = {Chemistry - a European journal},
  volume    = {25},
  journal   = {Chemistry - a European journal},
  number    = {21},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.201806132},
  pages     = {5498 -- 5506},
  year      = {2019},
  abstract  = {3-Bromopyruvic acid (3BP) is a potential anticancer drug, the action of which on cellular metabolism is not yet entirely clear. The presence of a bromine atom suggests that it is also reactive towards low-energy electrons, which are produced in large quantities during tumour radiation therapy. Detailed knowledge of the interaction of 3BP with secondary electrons is a prerequisite to gain a complete picture of the effects of 3BP in different forms of cancer therapy. Herein, dissociative electron attachment (DEA) to 3BP in the gas phase has been studied both experimentally by using a crossed-beam setup and theoretically through scattering and quantum chemical calculations. These results are complemented by a vacuum ultraviolet absorption spectrum. The main fragmentation channel is the formation of Br- close to 0 eV and within several resonant features at 1.9 and 3-8 eV. At low electron energies, Br- formation proceeds through sigma* and pi* shape resonances, and at higher energies through core-excited resonances. It is found that the electron-capture cross-section is clearly increased compared with that of non-brominated pyruvic acid, but, at the same time, fragmentation reactions through DEA are significantly altered as well. The 3BP transient negative ion is subject to a lower number of fragmentation reactions than those of pyruvic acid, which indicates that 3BP could indeed act by modifying the electron-transport chains within oxidative phosphorylation. It could also act as a radio-sensitiser.},
  language  = {en}
}
@article{DasElTawargyKhechineetal.2019,
  author    = {Das, Abhijna and El-Tawargy, Ahmed S. and Khechine, Emna and Noack, Sebastian and Schlaad, Helmut and Reiter, G{\"u}nter and Reiter, Renate},
  title     = {Controlling Nucleation in Quasi-Two-Dimensional Langmuir Poly(L-lactide) Films through Variation of the Rate of Compression},
  series = {Langmuir},
  volume    = {35},
  journal   = {Langmuir},
  number    = {18},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.9b00619},
  pages     = {6129 -- 6136},
  year      = {2019},
  abstract  = {We studied morphological changes in a quasi-two-dimensional Langmuir film of low molar mass poly(L-lactide) upon increasing the surface density, starting from randomly distributed molecules to a homogeneous monolayer of closely packed molecules, followed by nucleation and growth of mesoscopic, three-dimensional clusters from an overcompressed monolayer. The corresponding nucleation density of mesoscopic clusters within the monolayer can be tailored through variation of the rate of compression. For a given surface density and temperature, the nucleation probability was found to increase linearly with the rate of compression, allowing to adjust the density of mesoscopic clusters over nearly 2 orders magnitude.},
  language  = {en}
}
@article{DebsharmaBehrendtLaschewskyetal.2019,
  author    = {Debsharma, Tapas and Behrendt, Felix Nicolas and Laschewsky, Andre and Schlaad, Helmut},
  title     = {Ring-opening metathesis polymerization of biomass-derived levoglucosenol},
  series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker},
  volume    = {58},
  journal   = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker},
  number    = {20},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1433-7851},
  doi       = {10.1002/anie.201814501},
  pages     = {6718 -- 6721},
  year      = {2019},
  abstract  = {The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100kgmol(-1) and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 degrees C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment.},
  language  = {en}
}