Search

Flavin compounds are of great interest in biochemistry because of their diverse functions in catalytic and photochemical processes. The intrinsic optical properties of flavins depend sensitively on their environment such as complexation with metal ions. Herein, we characterize the interaction of alkali metal ions (M

Nanostructured Ge is considered a highly promising material for Li-ion battery applications as Ge offers high specific capacity and Li-ion diffusivity, while inherent mesoporous nanostructures can ...

Flavins are key compounds in many photochemical and photophysical processes used by nature, because their optical properties strongly depend on the (de-)protonation site and solvation. Herein, we present the vibronic optical spectrum of protonated lumiflavin (H+LF), the parent molecule of the flavin family, obtained by visible photodissociation (VISPD) spectroscopy in a cryogenic ion trap. By comparison to time-dependent density functional theory (TD-DFT) calculations at the PBE0/cc-pVDZ level coupled to multidimensional Franck–Condon simulations, the spectrum recorded in the 420–500 nm range is assigned to vibronic bands of the optically bright S1 ← S0(ππ*) transition of the two most stable H+LF tautomers protonated at the O2+ and N1 position. While the most stable O2+ protomer has been identified previously by infrared spectroscopy, the N1 protomer is identified here for the first time. The S1 band origins of H+LF(O2+) and H+LF(N1) at 23 128 and 23 202 cm−1 are shifted by 1617 and 1691 cm−1 to the blue of that of bare LF measured in He droplets, indicating that the proton affinity of both tautomers is slightly reduced upon S1 excitation. This view is consistent with the molecular orbitals involved in the assigned ππ* transition. The spectrum of both protomers is rich in vibrational structure indicating substantial geometry changes by ππ* excitation. Interestingly, while the O2+ protomer is planar in both electronic states, the N1 protomer is slightly nonplanar giving rise to large vibrational activity of low-frequency out-of-plane modes. Comparison with protonated lumichrome and metalated lumiflavin reveals the impact of functional groups and the type of the attached cation (proton or alkali ion) on the geometric and electronic structure of flavins.

Aromatized wines and regular table wines are often filled on the same bottling line. Sealing polymers in the filling line absorb volatiles from aromatized wines and may migrate due to insufficient cleaning into the subsequently bottled regular wine. Unintentional carryover of volatiles may lead to accusation of illegal aromatization of wine. Absorption, cleaning efficacy, and migration of volatiles into ethylene propylene diene monomer rubber were investigated in a model system. Direct thermal desorption-gas chromatography-mass spectrometry analysis of seven aroma compounds monitored variation in the polymer (μg/g). Absorption of volatiles was mostly driven by their octanol/water partition coefficients. Cleaning of polymers removed 11 to 62% of the absorbed volatiles. Subsequent immersion of cleaned polymers into model wine revealed migration of 20 to 57% of the remaining volatiles. Sensory tests suggested the impact of transferred volatiles into subsequent model wine. For α-ionone, an odor activity value of 1.03 indicated a potential sensory impact.

Solid electrolytes with superionic conductivity are required as a main component for all-solid-state batteries. Here we present a novel solid electrolyte with three-dimensional conducting pathways based on "lithium-rich" phosphidosilicates with ionic conductivity of σ > 10-3 S cm-1 at room temperature and activation energy of 30-32 kJ mol-1 expanding the recently introduced family of lithium phosphidotetrelates. Aiming toward higher lithium ion conductivities, systematic investigations of lithium phosphidosilicates gave access to the so far lithium-richest compound within this class of materials. The crystalline material (space group Fm3m), which shows reversible thermal phase transitions, can be readily obtained by ball mill synthesis from the elements followed by moderate thermal treatment of the mixture. Lithium diffusion pathways via both tetrahedral and octahedral voids are analyzed by temperature-dependent powder neutron diffraction measurements in combination with maximum entropy method and DFT calculations. Moreover, the lithium ion mobility structurally indicated by a disordered Li/Si occupancy in the tetrahedral voids plus partially filled octahedral voids is studied by temperature-dependent impedance and 7Li NMR spectroscopy.

A von Hamos geometry based wavelength dispersive spectrometer combined with an in situ reactor cell has been developed to measure non-resonant sulfur Kα emission for the in situ speciation of low concentrations of sulfur. The spectrometer operates at 15 cm focusing radius, is equipped with a curved Si(111) crystal and a position sensitive detector, and is capable of achieving an energy resolution of 0.56 eV at 2.3 keV. We present the details of the spectrometer and dedicated sample-cell design to study chemical reactions in situ. The spectrometer capabilities are exemplified by an in situ study of sulfur speciation during H2S poisoning of SiO2 supported Ru nanoparticles performing CO methanation.

Flavin compounds are frequently used by nature in photochemical processes because of their unique optical properties which can be strongly modulated by the surrounding environment such as solvation or coordination with metal ions. Herein, we employ vibronic photodissociation spectroscopy of cryogenic M+LF complexes composed of lumiflavin (LF, C13H12N4O2), the parent molecule of the flavin family, and alkali ions (M = Li–Cs) to characterize the strong impact of metalation on the electronic properties of the LF chromophore. With the aid of time-dependent density functional theory calculations (PBE0/cc-pVDZ) coupled to multidimensional Franck–Condon simulations, the visible photodissociation (VISPD) spectra of M+LF ions recorded in the 500–570 nm range are assigned to the S1 ← S0 (ππ*) transitions into the first optically bright S1 state of the lowest-energy M+LF(O4+) isomers. In this O4+ structure, M+ binds in a bent chelate to the lone pairs of both the O4 and the N5 atom of LF. Charge reorganization induced by S1 excitation strongly enhances the interaction between M+ and LF at this binding site, leading to substantial red shifts in the S1 absorption of the order of 10–20% (e.g., from 465 nm in LF to 567 nm in Li+LF). This strong change in M+⋯LF interaction strength in M+LF(O4+) upon ππ* excitation can be rationalized by the orbitals involved in the S1 ← S0 transition and causes strong vibrational activity. In particular, progressions in the intermolecular bending and stretching modes provide an accurate measure of the strength of the M+⋯LF bond. In contrast to the experimentally identified O4+ ions, the predicted S1 origins of other low-energy M+LF isomers, O2+ and O2, are slightly blue-shifted from the S1 of LF, demonstrating that the electronic properties of metalated LF not only drastically change with the size of the metal ion but also with its binding site.

Perovskite-structured powders of SrTi1-xCoxO3-δ (STC-x) with nominal stoichiometry of x = 0–0.75 as well as SrTi0.75Co0.25-yFeyO3-δ (STCF-y) where y = 0–0.25 were synthesized using the Pechini method. Thermal/chemical expansion behaviour, total electrical conductivities, and oxygen permeation rates were investigated. The substitution of Ti with Co leads to an increase in both electronic and ionic conductivities and, therefore, oxygen permeability. Thermal and chemical expansions also increase slightly. The optimum Co content was found to be 25–35% due to the trade-off between phase stability and permeability. The oxygen permeation rate of STC35 is comparable to that of state-of-the-art (La,Sr)(Co,Fe)O3-δ, whereas the expansion coefficients are lower. Co-doping in STCF-y did not produce any significant differences in oxygen permeability at both high temperature and sample thickness (1.0 mm), i.e. in a solid-state diffusion-limited regime. At lower temperatures (

Pancreatic ductal adenocarcinoma (PDAC) relies on hyperactivated protein synthesis. Consistently, human and mouse PDAC lose expression of the translational repressor and mTOR target 4E-BP1. Using genome-wide polysome profiling, we here explore mRNAs whose translational efficiencies depend on the mTOR/4E-BP1 axis in pancreatic cancer cells. We identified a functional enrichment for mRNAs encoding DNA replication and repair proteins, including RRM2 and CDC6. Consequently, 4E-BP1 depletion favors DNA repair and renders DNA replication insensitive to mTOR inhibitors, in correlation with a sustained protein expression of CDC6 and RRM2, which is inversely correlated with 4E-BP1 expression in PDAC patient samples. DNA damage and pancreatic lesions induced by an experimental pancreatitis model uncover that 4E-BP1/2-deleted mice display an increased acinar cell proliferation and a better recovery than WT animals. Targeting translation, independently of 4E-BP1 status, using eIF4A RNA helicase inhibitors (silvestrol derivatives) selectively modulates translation and limits CDC6 expression and DNA replication, leading to reduced PDAC tumor growth. In summary, 4E-BP1 expression loss during PDAC development induces selective changes in translation of mRNA encoding DNA replication and repair protein. Importantly, targeting protein synthesis by eIF4A inhibitors circumvents PDAC resistance to mTOR inhibition.

The optical properties of flavins strongly depend on the charge and oxidation states as well as the environment. Herein, the electronic spectrum of cold protonated lumichrome, the smallest flavin molecule, is recorded by means of photodissociation in the visible range (VISPD) in a cryogenic ion trap tandem mass spectrometer coupled to an electrospray ionization source. The vibronic spectrum is assigned to the S1 ← S0 (ππ*) transition of the most stable N5-protonated isomer by comparison with quantum chemical calculations at the PBE0/cc-pVDZ level in combination with multidimensional Franck-Condon simulations. Analysis of the geometric and electronic structures of neutral and protonated lumichrome explains the large red shift of the band origin upon protonation (ΔS1 ∼ -6000 cm-1), which corresponds to the increase in proton affinity upon S1 excitation as a result of charge transfer. N5 protonation greatly modifies the structure of the central pyrazine ring of the chromophore. The orbitals involved in S1 ← S0 excitation include an important fraction of the probability at the central ring and they are, hence, largely influenced by the positive charge of the attached proton. The rich vibronic spectrum indicates the large geometry change upon S1 excitation. This combined experimental and computational approach is shown to be suitable to determine the optical properties of flavins as a function of oxidation, protonation, metalation, and microsolvation state.

Sensitive detection and quantification of individual plasmonic nanoparticles is critical in a range of applications in the biological, nanomaterials, and analytical sciences. Although a wide range of techniques can be applied to the analysis of immobilized particles, high-throughput analysis of nanoscale species in flow is surprisingly underdeveloped. To address this shortcoming, we present an ultrasensitive, background-free technique based on the photothermal effect and termed differential detection photothermal interferometry (DDPI). We show, both theoretically and experimentally, that DDPI can specifically extract either the phase or amplitude of a photothermal signal. We then quantitatively detect 10 and 20 nm diameter gold nanoparticles at femtomolar concentrations and at linear flow speeds of 10 mm/s. In the case of 50 nm gold particles, we operate at an even higher linear flow speed of 100 mm/s, corresponding to an analyzed volume of more than 1 nL/s. This allows quantification of particle content at attomolar to femtomolar concentrations and counting rates between 0.1 and 400 particles per second. Finally, we confirm that the signal follows the size-dependent variations predicted by Mie theory.

Extracellular nucleotides mediate multiple physiological effects such as proliferation, differentiation, or induction of apoptosis through G protein–coupled P2Y receptors or P2X ion channels. Evaluation of the complete physiological role of nucleotides has long been hampered by a lack of potent and selective ligands for all P2 subtypes. Meanwhile, for most of the P2 receptors, selective ligands are available, but only a few potent and selective P2Y(2) receptor antagonists are described. This limits the understanding of the role of P2Y(2) receptors. The purpose of this study was to search for P2Y(2) receptor antagonists by a combinatorial screening of a library of around 415 suramin-derived compounds. Calcium fluorescence measurements at P2Y(2) receptors recombinantly expressed in human 1321N1 astrocytoma cells identified NF272 [8-(4-methyl-3-(3-phenoxycarbonylimino-benzamido)benzamido)-naphthalene-1,3,5-trisulfonic acid trisodium salt] as a competitive P2Y(2) receptor antagonist with a K(i) of 19 μM which is 14-fold more potent than suramin at this receptor subtype. The SCHILD analysis of competitive inhibition resulted in a pA(2) value of 5.03 ± 0.22 (mean ± SEM) with a slope not significantly different from unity. Among uracil-nucleotide–preferring P2Y receptors, NF272 shows a moderate selectivity over P2Y(4) (3.6-fold) and P2Y(6) (5.7-fold). However, NF272 is equipotent at P2Y(1), and even more potent at P2Y(11) and P2Y(12) receptors. Up to 250 μM, NF272 showed no cytotoxicity in MTT cell viability assays in 1321N1, HEK293, and OVCAR-3 cells. Further, NF272 was able to inhibit the ATP-induced calcium signal in OVCAR-3 cells demonstrated to express P2Y(2) receptors. In conclusion, NF272 is a competitive but non-selective P2Y(2) receptor antagonist with 14-fold higher potency than suramin lacking cytotoxic effects. Therefore, NF272 may serve as a lead structure for further development of P2Y(2) receptor antagonists. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11302-019-09663-4) contains supplementary material, which is available to authorized users.

The implementation of the hydroformylation reaction for the conversion of long-chain alkenes into aldehydes still remains challenging on an industrial scale. One possible approach to overcoming this challenge is to apply tunable systems employing surfactants. Therefore, a novel process concept for the hydroformylation of long-chain alkenes to aldehydes in microemulsions is being investigated and developed at Technische Universitat Berlin, Germany. To test the applicability of this concept for the hydroformylation in microemulsions on a larger scale, a miniplant has been constructed and operated. This contribution presents the proof of concept for hydroformylation in microemulsions carried out during a 200 h miniplant operation. Throughout the operation a stable aldehyde yield of 21% and a catalyst loss in the product phase below 0.1 ppm were achieved, which confirms previous lab scale findings. Additionally, solution strategies for a stable continuous operation to overcome challenges such as foaming, phas...

Microemulsion systems are smart solvent systems which can be applied in homogeneous catalysis. We investigate these multiphase systems to exploit their characteristics for catalytic gas/liquid reactions and processes in aqueous media. One critical aspect from an economic perspective is the quantitative recycling of the catalyst complex dissolved in the multiphase system. Therefore, it is important to know the distribution of the catalyst complex in each of the single phases. In this contribution we analyse the different parameters/factors that may have an influence on the distribution of catalyst complexes in microemulsion systems, e.g. temperature, type of ligand, structure of surfactant, and chain length of surfactant. Afterwards, the derived information is used for the design of a real, industry-oriented application: hydroformylation of long chained alkenes. Hereby, special attention is given to the separation step of a process, which is performed after a homogeneously catalyzed reaction step in a microemulsion system. Process and economic constraints are briefly outlined and compared with operation data, aiming for the reuse of the catalyst in the reaction step and reduced leaching into product streams, even in the case of operational disturbances and shifts in the catalyst distribution.

We investigate aqueous multiphase systems for catalytic gas/liquid reactions, namely, the rhodium-catalyzed hydroformylation of the long-chain olefin 1-dodecene. The multiphase system was formulated from 1-dodecene, water, and a nonionic surfactant, which increases the solubility between the two nonmiscible liquid phases. On the basis of these systems, we present in this paper a transfer of lab experiments (semibatch) to a successful operation of a miniplant in continuous mode. Under optimized conditions, the reaction showed turnover frequencies of ∼200 h–1 and high selectivity of 98:2 to the desired linear aldehyde. The miniplant was operated continuously for a total of 130 h. The control of the phase separation and catalyst recycling for product isolation for a long time period appeared to be challenging. Nevertheless, the separation was kept stable for over 24 h. The organic components in the product phase amounted to desired values between 95 and 99 wt %. The desired 99.99% of the catalyst remained in...

The photochemical properties of flavins depend sensitively on their environment and are strongly modified by coordination with metal ions. Herein, the electronic spectra of cold complexes of the smallest flavin molecule (lumichrome, LC, C12N4O2H10) with alkali ions (M+LC, M = Li–Cs) are measured by photodissociation in the visible range (VISPD) in a cryogenic ion trap coupled to a tandem mass spectrometer and an electrospray ionization source. The observed vibronic spectra of all ions are assigned to the optically bright S1 ← S0 (ππ*) transition of the most stable O4 isomer of M+LC by comparison with quantum chemical calculations at the PBE0/cc-pVDZ level coupled to multidimensional Franck–Condon simulations. The rich vibronic spectra indicate substantial geometry changes upon S1 excitation. Large red shifts of the S1 origins upon metal complexation and progressions in the intermolecular in-plane metal stretch and bend modes demonstrate that the strength of the metal–flavin interaction in M+LC(O4) strongly increases by S1 excitation. The stronger M+⋯LC bond in the S1 state of M+LC(O4) is rationalized by the charge reorganization upon ππ* excitation of the LC chromophore. The computations confirm that the optical properties of LC can be strongly modulated by metalation via both the type and binding site of the metal ion.

We report the use of inverse supercritical fluid extraction (SFE) and miniaturized asymmetrical flow field-flow fractionation (mAF4) for the preparation and subsequent analysis of titanium dioxide nanoparticles in model and commercial sunscreens. The approach allows for the fast and reliable fractionation and sizing of TiO2 nanoparticles and their quantitation in commercial products. This new method represents a powerful and efficient tool for the verification of nanoparticle content in a wide range of matrixes, as demanded by recently introduced regulatory requirements. Furthermore, the use of carbon dioxide as an environmentally friendly solvent is in line with the increasing need for ecologically compatible analytical techniques.

The focus of this contribution is the separation of carbon dioxide from biogas and hydrocarbon containing gaseous reaction products using a high flux flat sheet membrane. The thin selective layer of the membranes is made from the commercial blockcopolymer PolyActive™. The membrane material is manufactured reproducibly on a technical scale and installed into membrane modules. The modules were investigated in three pilot plants: two for the removal of carbon dioxide from methane and one for the separation of carbon dioxide from gaseous hydrocarbon streams. The pilot plant experiments confirmed a rapid approach to steady state operation and the dependence of the separation result on the employed pressure ratio. For the biogas applications it was shown that a single stage process is sufficient to achieve methane purities in excess of 95 mol% in the retentate at methane recoveries of 70%, as well as carbon dioxide mole fractions larger than 60 mol% in the permeate. Carbon dioxide could also be removed successfully from gaseous, hydrocarbon containing product streams employing the investigated high flux membranes. The employed simulation model for the modules predicted the experimental results well and proofed to be a valuable tool.

Optimization is scarcely ever carried out during process synthesis. Nonetheless, this contribution shows that optimization at the design stage can be vital to make new process concepts economically feasible and open up new, cleaner production paths. Herein, a hybrid separation system for the carbon dioxide removal from product gas of the oxidative coupling of methane is investigated. The combination of a polyimide and a polyethylene oxide membrane as well as an amine-based absorption process is investigated, modeled, and subsequently optimized to minimize the required energy while keeping the loss of the reaction product at a minimum. By means of process optimization at the synthesis stage process configurations are discovered, which allows for the realization of an alternative process concept to improve greenhouse gas emission reduction. Furthermore, new reaction paths towards the synthesis of longer hydrocarbons based on natural or bio gas are enabled.

Within the framework of the Collaborative Research Centre SFB/TR 63 InPROMPT, “Integrated chemical processes in liquid multiphase systems”, a novel process concept for the hydroformylation of long chain alkenes to aldehydes in microemulsions is investigated and developed at the Berlin Institute of Technology (Technische Universitat Berlin), Germany. To start the hydroformylation reaction, a hydrophilic rhodium-ligand-complex is required. By applying a nonionic surfactant, a microemulsion system is formed and thus the hydrophilic catalyst is transported into the hydrophobic alkene phase. Next to achieve a high conversion rate in the continuously stirred tank reactor, the separation of the valuable rhodium catalyst from the product phase poses a challenge. This separation is the crucial step for the technical and economic feasibility of the overall process concept and plant design. Owing to the lack of thermodynamic data for microemulsion mixtures, the design of the phase separation unit strongly depends on...

Erratum to : J. Am. Soc. Mass Spectrom (2016) DOI: 10.1007/s13361-016-1415-z In the preceding article BGas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions^ by Wisdorf et al., the errors as listed below were not appropriately corrected during the final galley proofing stage. Errors number 1–4were present in the submitted revised manuscript, errors 5 and 6 appeared additionally in the galley proofs. The authors are indebted to Dr. Martin F. Jerrold, Chemistry Department, Indiana University, who found inconsistencies caused by errors number 2–4 when analyzing our data using the online version of the article and reported these immediately to us. We sincerely apologize for this mishap. It is emphasized though that all calculations presented in the preceding articlewere computed with the correct equations and the appropriate units as given below. None of the data, figures, and conclusions drawn in the article are thus affected.

In this work, the characteristics of gas flow in inlet capillaries are examined. Such inlet capillaries are widely used as a first flow restriction stage in commercial atmospheric pressure ionization mass spectrometers. Contrary to the common assumption, we consider the gas flow in typical glass inlet capillaries with 0.5 to 0.6 mm inner diameters and lengths about 20 cm as transitional or turbulent. The measured volume flow of the choked turbulent gas stream in such capillaries is 0.8 L·min(-1) to 1.6 L·min(-1) under typical operation conditions, which is in good agreement to theoretically calculated values. Likewise, the change of the volume flow in dependence of the pressure difference along the capillary agrees well with a theoretical model for turbulent conditions as well as with exemplary measurements of the static pressure inside the capillary channel. However, the results for the volume flow of heated glass and metal inlet capillaries are neither in agreement with turbulent nor with laminar models. The velocity profile of the neutral gas in a quartz capillary with an inner diameter similar to commercial inlet capillaries was experimentally determined with spatially resolved ion transfer time measurements. The determined gas velocity profiles do not contradict the turbulent character of the flow. Finally, inducing disturbances of the gas flow by placing obstacles in the capillary channel is found to not change the flow characteristics significantly. In combination the findings suggest that laminar conditions inside inlet capillaries are not a valid primary explanation for the observed high ion transparency of inlet capillaries under common operation conditions. Graphical Abstract ᅟ.

Results obtained with two computational approaches for the simulation of ion motion at elevated pressure are compared with experimentally derived ion current data. The computational approaches used are charged particle tracings with the software package SIMION ver. 8 and finite element based calculations using the software package Comsol Multiphysics ver. 4.0/4.0a. The experimental setup consisted of a tubular corona discharge ion source coupled to a cylindrical measurement chamber held at atmospheric pressure. Generated ions are flown into the chamber at essentially subsonic laminar isothermal conditions. In the simulations, strictly stationary conditions were assumed. The results show very good agreement between the SIMION/SDS model and experimental data. For the Comsol model, only qualitative agreement is observed.

The reaction of hydrazine hydrate with KSeCN in acidic aqueous ethanol in the presence of cyclohexanone affords cyclohexanone selenosemicarbazone in good yields. Cyclohexanone selenosemicarbazone was converted into various functionalised selenosemicarbazones by treatment with aldehydes. Salicylaldehyde selenosemicarbazone and its 1,2-naphthyl-derivative were prepared and reacted with some Pd(II) and Pt(II) phosphine complexes to give compounds of the type [M(LSe)(P)] where M = Pt and Pd, LSe is the doubly deprotonated selenosemicarbazone and P a monodentate phosphine. In these complexes the ligands act as tridentate, dianionic [Se–N–O]2- ligands, which was confirmed by single-crystal X-ray diffraction of the Pd derivative.

Monodisperse oligophenothiazines are rapidly synthesized in good yields by use of Suzuki arylation. These well defined oligomers reveal both highly fluorescence and low oxidation potentials. As a consequence of intense electronic coupling as supported by cyclic voltammetry a selected trimer shows hole-transport properties in a hole-conductor-only set-up of a diode with relatively low on-set voltage.

We demonstrate the use of inverse supercritical carbon dioxide (scCO2) extraction as a novel method of sample preparation for the analysis of complex nanoparticle-containing samples, in our case a model sunscreen agent with titanium dioxide nanoparticles. The sample was prepared for analysis in a simplified process using a lab scale supercritical fluid extraction system. The residual material was easily dispersed in an aqueous solution and analyzed by Asymmetrical Flow Field-Flow Fractionation (AF4) hyphenated with UV- and Multi-Angle Light Scattering detection. The obtained results allowed an unambiguous determination of the presence of nanoparticles within the sample, with almost no background from the matrix itself, and showed that the size distribution of the nanoparticles is essentially maintained. These results are especially relevant in view of recently introduced regulatory requirements concerning the labeling of nanoparticle-containing products. The novel sample preparation method is potentially applicable to commercial sunscreens or other emulsion-based cosmetic products and has important ecological advantages over currently used sample preparation techniques involving organic solvents.

For absorption processes with fluctuating feed gas compositions it is vital to continuously adjust the operation point to achieve energy efficiency. In this contribution a Raman-based advanced process control (APC) is introduced for the absorption of carbon dioxide (CO2) using an aqueous solution of monoethanolamine (MEA). The APC is based on a Raman spectroscopic analysis of the composition and CO2 load of the scrubbing liquid and a non-linear model predictive control (NMPC) to adjust the scrubbing liquid cycle. In addition, an outer real-time optimization loop is set in place to update the set points for the absorption process depending on the current feed gas composition minimizing the energy consumption of the process. Implementation and testing of the APC have been carried out in a mini-plant at TU Berlin. During a plant operation of more than 160 hours robustness and stability of the APC were shown.

Novel polymeric hole-transporters P1 through P4 were synthesized based on triarylamine units in the backbone with pendant oxetane groups which can be used for photo-cross-linking. These polymers were characterized by NMR spectroscopy, GPC, IR spectroscopy, and DSC. Their electrochemical properties were investigated by means of cyclic voltammetry. Multilayer organic light emitting devices were fabricated layer by layer using inexpensive solution based methods like spin-coating followed by a cross-linking step. UV spectroscopy was used to prove that the spin-coated layers are totally insoluble after the cross-linking process. The hole-transport capabilities of the polymers were evaluated in hole-only devices and finally multilayer OLEDs were fabricated to test the performance of the synthesized compounds.

The synthesis and characterization of side-chain polymers functionalized with hole-transporting units and photo-cross-linkable groups, which can be used for solution-based preparation of multilayer organic light-emitting devices (OLEDs), are discussed. The concept deals with triarylamine and oxetane-functionalized styrenes, which are copolymerized by radical polymerization. Four different types of hole-transporting monomers were combined with one cross-linkable monomer in two different ratios, yielding two groups of each four polymers (P1A...P4A and P1B...P4B). The polymers were investigated by NMR spectroscopy, molecular weights were determined by GPC with light scattering, and the thermal properties were measured with differential scanning calorimetry (DSC). Optical characterization by UV−vis and fluorescence spectroscopy was performed. Electrochemical and cross-linking characteristics of the copolymers were investigated to proove this strategy's potential in application for modern multilayer polymer OL...

Zimt ist eines der Altesten GewUrze der Welt und wird aus der Rinde von ZimtbAumen der Gattung Cinnamomum, Familie Lauraceae, hergestellt. Diese BAume werden hauptsAchlich in tropischen LAndern wie Sri Lanka, Indien, SUd-China, Indonesien und Sumatra angebaut. HauptsAchlich die Arten Cinnamomum zeylanicum (Ceylon-Zimt), Cinnamomum aromaticum (China-Zimt) und Cinnamomum burmanii (Padang-Zimt) werden fUr die Zimtherstellung verwendet. Als GewUrz sowie auch als Heilmittel ist Zimt vielseitig einsetzbar. Neueste Studien zeigen, dass ein Polyphenol aus Zimt, das «Methylhydroxy-Chalcone-Polymer», kurz MHCP, den Serumglucosespiegel bei Typ-2-Diabetikern senken kann. MHCP wirkt insulinAhnlich am Insulinrezeptor der KOrperzellen und hat in Kombination mit Insulin einen synergistischen Effekt auf dessen Funktion. ZusAtzlich wirkt sich das MHCP auch positiv auf den Triglyceridspiegel, auf den Gesamt-Cholesterin- und den LDL-Cholesterinspiegel im Serum aus. Zimt als GewUrz hat ein nicht zu unterschAtzendes allergenes Potential, das auf den Gehalt an Zimtaldehyd im Atherischen Ol basiert. Reiner Zimtaldehyd hat sensibilisierende Eigenschaften und kann zu allergischen Reaktionen wie Hautirritationen fUhren. WAssriger Zimtextrakt enthAlt dagegen kein Atherisches Ol, aber in hoher Konzentration das blutzuckersenkende Polyphenol MHCP. Dadurch ist eine gute VertrAglichkeit und eine hohe physiologische Wirksamkeit von wAssrigem Zimtextrakt gegeben. Ebenso ist dadurch eine Daueranwendung von wAssrigem Zimtextrakt zusAtzlich zur diAtetischen Basistherapie bei Diabetes mellitus Typ 2 mOglich. WAssriger Zimtextrakt kann ein Bestandteil der adjuvanten Diabetestherapie sein.

Thermal annealing of organic light-emitting diodes based on polymer composites prior to the metal deposition is found to substantially improve the devices' luminescence efficiency. Phase separation between the matrix polymer and the hole conducting low molecular weight component is shown to be the origin of this behavior. We use atomic force microscopy along with selective dissolution of one of the components to establish the domain morphology of the devices. The presence of the metal electrode is shown to significantly influence the phase separation process. Finally, a correlation between the domain morphology and the electrooptical properties is established.

Organic light-emitting diodes (OLEDs) show promise for applications as high-quality self-emissive displays for portable devices such as cellular phones and personal organizers. Although monochrome operation is sufficient for some applications, the extension to multi-colour devices--such as RGB (red, green, blue) matrix displays--could greatly enhance their technological impact. Multi-colour OLEDs have been successfully fabricated by vacuum deposition of small electroluminescent molecules, but solution processing of larger molecules (electroluminescent polymers) would result in a cheaper and simpler manufacturing process. However, it has proved difficult to combine the solution processing approach with the high-resolution patterning techniques required to produce a pixelated display. Recent attempts have focused on the modification of standard printing techniques, such as screen printing and ink jetting, but those still have technical drawbacks. Here we report a class of electroluminescent polymers that can be patterned in a way similar to standard photoresist materials--soluble polymers with oxetane sidegroups that can be crosslinked photochemically to produce insoluble polymer networks in desired areas. The resolution of the process is sufficient to fabricate pixelated matrix displays. Consecutive deposition of polymers that are luminescent in each of the three RGB colours yielded a device with efficiencies comparable to state-of-the-art OLEDs and even slightly reduced onset voltages.

Organic light emitting devices (OLEDs) are one of the most promising alternatives to liquid crystal displays (LCDs) concerning flat panel display applications. The OLED technique is based on organic semiconductors used either as hole- or electron transporting materials or as emitter. Working on common problems in OLED preparation, performance and life time, novel and improved charge transport molecules and polymers of triarylamine- and poly(para-phenylene)type are introduced. This includes: (1) cyclic triarylamine-derivatives with enhanced glass transition temperature; (2) triarylamine based low molecular mass hole transport molecules and hole transport polymers with pendant oxetane groups for processing out of solution and subsequent crosslinking; and (3) fluorenyl-segmented poly(para -phenylene)s with defined electrochemical properties.

The intense sweetener Neohesperidine DC, made from a natural substance, is suitable for use in a wide range of food products, to round and balance their sensory profile. Particularly calorie-reduced products can be made more acceptable. Neohesperidine DC is also suitable for use in pharmaceuticals because of his high stability and flavour modifying properties. Neohesperidine DC has advantages over other sweeteners: ” due to its intense sweetness, only small amounts are required; ” synergy properties with other sweeteners, therefore requirements and costs are reduced; ” flavour modifying properties: reduction of bitterness and aftertastes associated with sweeteners; enhancement of pleasant flavours; ” high sensory stability to thermal processing and storage; can be used in a wide range of products; ” enhances taste and the mouthfeel of calorie- and fat-reduced products. Substitution of sucrose with other sweeteners is particularly useful in products, where high amounts are used, so that consumption of thes...

Using a derivative of the blue-emitting polyfluorene (see the graph for the output spectrum and the inset picture for the color), efficient devices exhibiting a power efficiency close to 2.7 cd A(-1) at 100 cd m(-2) light output were realized.

Combination of spin-coating and crosslinking allows low-cost fabrication of large area displays with multiple layers by simple solution processing. For this purpose, a series of novel crosslinkable polymers containing hole-transporting triarylamine units in the main chain were synthesized via palladium-catalyzed C-N-coupling reaction. Additionally, the contain varying amounts of polymerizable oxetane groups as side chains. The polymers were photo-crosslinked to yield absolutely insoluble networks. Thin films were used as hole-transport layer in two-layer blue light-emitting diodes. Absorption spectrum of a films of 8c crosslinked on ITO and cured at 150°C before and after washing with THF. Crosslinking was carried out in bulk with 2 wt.-% of photoacid 4-(thio-phenoxyphenyl)dephenylsulfonium hexafluoroantimonate 18) by irradiation with UV light (>280nm) for 10 s

Thin films of a cross-linkable hole-conducting monomeric triarylamine were investigated. The rate of photocross-linking and the overall polymerization yield were measured using real-time FT-IR spectroscopy. The electrical properties were characterized in a typical diode configuration using indium tin oxide and aluminum as the contacts. The current passed through the devices was found to be limited by the injection of holes into the semi-conducting polymer layer by tunneling. Cross-linked layers withstood about 20 times higher currents than non-cross-linked layers before dielectric breakdown occurred.

Our approach to prepare multilayer light emitting devices (LEDs) by low-cost spin-coating techniques is the combination of spin-coating and photo-crosslinking. The oxetane functionality was used as the polymerizable moiety, which was crosslinked in bulk by a cationic mechanism. The resulting films were resistant against solvents used in subsequent spin-coating steps. The synthesis of bis-functionalized hole transporting triarylamines by palladium catalyzed C—N-coupling reaction, their polymerization, characterization, and first application in two-layer blue light emitting OLEDs are presented.

In eukaryotes, mRNA translation is dependent on the cap-binding protein eIF4E. Through its simultaneous interaction with the mRNA cap structure and with the ribosome-associated eIF4G adaptor protein, eIF4E physically posits the ribosome at the 5' extremity of capped mRNA. eIF4E activity is regulated by phosphorylation on a unique site by the eIF4G-associated kinase MNK. eIF4E assembly with the eIF4G-MNK sub-complex can be however antagonized by the hypophosphorylated forms of eIF4E-binding protein (4E-BP). We show here that eIF4E phosphorylation is dramatically affected by disruption of eIF4E-eIF4G interaction, independently of changes in MNK expression. eIF4E phosphorylation is actually strongly downregulated upon eIF4G shutdown or upon sequestration by hypophosphorylated 4E-BP, consequent to mTOR inhibition. Downregulation of 4E-BP renders eIF4E phosphorylation insensitive to mTOR inhibition. These data highlight the important role of 4E-BP in regulating eIF4E phosphorylation independently of changes in MNK expression.

The sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) signaling pathway has been reported to modulate the expression of the canonical transcription factor hypoxia-inducible HIF-1α in multiple cell lineages. HIF-2α is also frequently overexpressed in solid tumors but its role has been mostly studied in clear cell renal cell carcinoma (ccRCC), the most common form of kidney cancer, where HIF-2α has been established as a driver of a more aggressive disease. In this study, the role of SphK1/S1P signaling with regard to HIF-2α was investigated in various cancer cell models including ccRCC cells. Under hypoxic conditions or in ccRCC lacking a functional von Hippel-Lindau (VHL) gene and expressing high levels of HIF-2α, SphK1 activity controls HIF-2α expression and transcriptional activity through a phospholipase D (PLD)-driven mechanism. SphK1 silencing promotes a VHL-independent HIF-2α loss of expression and activity and reduces cell proliferation in ccRCC. Importantly, downregulation of SphK1 is associated with impaired Akt and mTOR signaling in ccRCC. Taking advantage of a monoclonal antibody neutralizing extracellular S1P, we show that inhibition of S1P extracellular signaling blocks HIF-2α accumulation in ccRCC cell lines, an effect mimicked when the S1P transporter Spns2 or the S1P receptor 1 (S1P1) is silenced. Here, we report the first evidence that the SphK1/S1P signaling pathway regulates the transcription factor hypoxia-inducible HIF-2α in diverse cancer cell lineages notably ccRCC, where HIF-2α has been established as a driver of a more aggressive disease. These findings demonstrate that SphK1/S1P signaling may act as a canonical regulator of HIF-2α expression in ccRCC, giving support to its inhibition as a therapeutic strategy that could contribute to reduce HIF-2 activity in ccRCC.

Polymer electrolyte membrane fuel cells (PEMFC) are believed to play an important role in the growing field of electric mobility. A key component is the gas diffusion layer (GDL), which has the task to supply reactant gases to the electrodes, to efficiently remove product water, and to provide good electrical and thermal contact.1 However, at high current densities, the formation of liquid water in the GDL can substantially reduce oxygen transport and thus fuel cell performance.2 GDL compression is an important parameter in the construction of a fuel cell. While high contact pressure reduces the contact resistance,3 high compression also results in a decrease in porosity, which leads to a lower effective diffusivity and higher mass transport resistance at dry conditions.4,5 Thus, there exists an optimum compression, taking into account the electrical and mass transport losses.6 However the influence of GDL compression on water condensation and mass transport resistance at wet conditions is still unclear. In this study we measure mass transport limiting currents for a commercial GDL (SGL Sigracet 25 BC) with a microporous layer (MPL), using a differential-flow cell at a variety of GDL compressions. By diluting the oxygen flow on the cathode, we could extract the mass transport resistance at both dry and wet conditions, following the analysis by Caulk and Baker. 2 Figure 1 shows polarization curves in the mass transport limited region below a cell voltage of 0.3 V for two GDL compressions corresponding to 7% and 20% of the initial thickness and three dry mole fractions of oxygen. At a low dry mole fraction of 1%, the limiting current densities of the two compressions are almost superimposed. However, at a high dry mole fraction of 24%, i.e., when large amounts of water are formed, the compression of 20% shows a much higher limiting current density compared to the less compressed material. In our study we will show how the mass transport resistance is affected by GDL compression at dry and wet conditions. Furthermore, we will show that the behavior at low compressions is consistent with the formation of a film of liquid water between the catalyst layer and the MPL, generating a barrier for the diffusion of oxygen to the electrode. Literature 1. J. M. Morgan and R. Datta, Journal of Power Sources 2014, 251, 269-278. 2. D. A. Caulk and D. R. Baker, Journal of the Electrochemical Society 2010, 157, B1237-B1244. 3. M. F. Mathias, J. Roth, J. Fleming and W. Lehnert in Handbook of Fuel Cells, Vol. 3, Eds.: W. Vielstich, H. A. Gasteiger and A. Lamm, John Wiley and Sons, Ltd, 2010. 4. D. R. Baker, D. A. Caulk, K. C. Neyerlin and M. W. Murphy, Journal of the Electrochemical Society 2009, 156, B991-B1003. 5. P. K. Das, X. G. Li and Z. S. Liu, Applied Energy 2010, 87, 2785-2796. 6. J. Ge, A. Higier and H. Liu, Journal of Power Sources 2006, 159, 922-927. Acknowledgements This work has been supported by the German Federal Ministry of Economy and Technology (BMWi) under agreement number 03ET6015E (“Optigaa 2” project). Figure 1: Polarization curves in the mass transport limited region below E cell = 0.3 V for dry oxygen mole fractions (x O2,dry) of 1%, 8% and 24 % and for GDL compressions of 7% and 20% of the initial thickness. Measurements are performed in a differential-flow cell at T cell = 50 °C, p in,abs = 200 kPa and RHAn/Ca = 77%. Dotted boxes indicate the extracted limiting current density i lim. Figure 1

Polymeric electrophosphorescent LEDs with internal quantum efficiencies approaching unity have been fabricated. Such performance levels are previously unknown for OLEDs. The key to this success is redox chemically doped oxetane- crosslinkable hole-transporting layers with multilayer capability (see figure). They improve hole injection and act as electron-blocking layers, without the need to include exciton-or hole-blocking layers

Organic light-emitting diodes (OLEDs) have recently attracted much interest among researchers as well as engineers as promising high quality self-emissive displays for all kinds of portable devices such as cellular phones, personal organisers, etc. While monochrome operation is sufficient for some applications, ultimately multi-color devices such as signs or even RGB (red, green, blue) matrix displays will be requested by the customer in the future. So far, this goal has been achieved with small-molecule devices fabricated by vacuum deposition. In contrast, electroluminescent (EL) polymers, which are commonly deposited by solution processing, seemed to be only poorly suited for this purpose owing to the lack of high-resolution patterning processes. Recent attempts, therefore, focus on the adaptation of common printing techniques such as screen printing and ink jetting, both having severe technical difficulties and drawbacks, such as limited resolution in the former and wetting issues in the latter case requiring extensive pre-treatment of the substrates. We demonstrate the use of a new class of EL polymers, which can be applied similar to a standard photoresist. Soluble polymers with oxetane sidegroups were crosslinked photochemically to yield insoluble polymer networks in the desired areas. The resolution of the process is sufficient to fabricate common pixelated matrix displays. Consecutive deposition of the three colors yielded a RGB device with efficiencies comparable to state-of-the-art EL polymers, even slightly reduced onset voltages, and improved efficiencies at high luminance levels. The improved thermal and morphological stability promises better performance in passive-matrix displays requiring high drive currents. The new method potentially allows efficient manufacturing of high-resolution multi-color polymer-based displays on large area using common lithography techniques.

PEDOT (Poly(3,4-ethylenedioxythiophene)) layers were prepared by electrochemical polymerization of the respective monomer. Thereafter, these layers were electrochemically adjusted to different equilibrium potentials and they were investigated with Kelvin Probe measurements. A change in work function could be observed yielding a linear correlation with the pre-adjusted electrochemical potential. These PEDOT layers have been utilized in OLEDs in their accessible range of work functions. Internal energy conditions of the OLEDs were characterized in a photovoltaic setup yielding a linear correlation of the open circuit voltage on the pre-adjusted potential. In a second step the efficiency was determined for devices with Ca cathode (space-charge-limited electron current) as well as for devices with Al cathode (injection-limited electron current). These devices could be optimized in efficiency by adjusting the hole current to the electron current, which was determined by the work function of the cathodic metal. The optimum could be explained in zero-order approximation in terms of a balanced bimolecular reaction between holes and electrons.

The current basement membrane (BM) model proposes a single-layered extracellular matrix (ECM) sheet that is predominantly composed of laminins, collagen IVs and proteoglycans. The present data show that BM proteins and their domains are asymmetrically organized providing human BMs with side-specific properties: A) isolated human BMs roll up in a side-specific pattern, with the epithelial side facing outward and the stromal side inward. The rolling is independent of the curvature of the tissue from which the BMs were isolated. B) The epithelial side of BMs is twice as stiff as the stromal side, and C) epithelial cells adhere to the epithelial side of BMs only. Side-selective cell adhesion was also confirmed for BMs from mice and from chick embryos. We propose that the bi-functional organization of BMs is an inherent property of BMs and helps build the basic tissue architecture of metazoans with alternating epithelial and connective tissue layers.

Organic light-emitting diodes based on composites using different hole conductors were fabricated and characterized. In these devices the current flux is limited by the injection of holes into the semi-conducting polymer layer through tunneling. The data were evaluated using the common Fowler-Nordheim formalism. The barrier height was found to depend linearly on the oxidation potential of the hole conductor, but unexpectedly the slope is only 0.55±0.1. This result is explained by the non-polar nature of the internal interface between ITO and the conductive layer.