Interaction of CO with planar Au/TiO2 model catalysts at elevated pressures

The interaction of CO with structurally well-defined, planar Au/TiO₂ model catalysts at elevated pressures (up to 50 mbar) was studied in-situ by polarization-modulated infrared reflection absorption spectroscopy and ex-situ by X-ray photoelectron spectroscopy performed before and after CO exposure. The results indicate a CO-induced partial reduction of the oxide surface, which is evidenced by a low frequency C–O vibration at 2060 cm⁻¹, combined with a spreading of the Au nanoparticles due to a modification of the Au-oxide interface energy. In a 2:1 CO:O₂ atmosphere, TiO₂ support reduction was not observed, and a pre-reduced surface was re-oxidized. The consequences of these results for the understanding of the CO oxidation mechanism on Au/TiO₂ (model) catalysts are discussed.     

Development of Diaminoquinazoline Histone Lysine Methyltransferase Inhibitors as Potent Blood‐Stage Antimalarial Compounds

Modulating epigenetic mechanisms in malarial parasites is an emerging avenue for the discovery of novel antimalarial drugs. Previously we demonstrated the potent in vitro and in vivo antimalarial activity of (1‐benzyl‐4‐piperidyl)[6,7‐dimethoxy‐2‐(4‐methyl‐1,4‐diazepin‐1‐yl)‐4‐quinazolinyl]amine (BIX01294; 1 ), a known human G9a inhibitor, together with its dose‐dependent effects on histone methylation in the malarial parasite. This work describes our initial medicinal chemistry efforts to optimise the diaminoquinazoline chemotype for antimalarial activity. A variety of analogues were designed by substituting the 2 and 4 positions of the quinazoline core, and these molecules were tested against Plasmodium falciparum (3D7 strain). Several analogues with IC₅₀ values as low as 18.5 nM and with low mammalian cell toxicity (HepG2) were identified. Certain pharmacophoric features required for antimalarial activity were found to be analogous to the previously published SAR of these analogues for G9a inhibition, thereby suggesting potential similarities between the malarial and human HKMT targets of this chemotype. Physiochemical, in vitro activity, and in vitro metabolism studies were also performed for a select set of potent analogues to evaluate their potential as antimalarial leads.     

Changes in endocrine profile and reproductive organs during puberty in the male marmoset monkey (Callithrix jacchus)

Data on pubertal maturation in male marmoset, a model for human reproduction, are scant and conflicting. We collected data on novel parameters to characterize puberty. Twenty-five marmoset monkeys were assigned to five age groups by weeks (wk): 21 (pre-pubertal), 43 (onset of puberty), 52 (fully pubertal), 70 (mature), and 116 (fully adult). Serum and intratesticular testosterone and pituitary bioactive chorionic gonadotropin (bioCG) were measured. Testicular development was assessed by ultrasonography, histology, and flow cytometry. Three consecutive blood samples revealed extreme fluctuations in testosterone concentrations, suggesting an erratic secretion. Age-related changes in serum testosterone and pituitary bioCG concentrations were observed. Intratesticular androgens (ITAs) showed high fluctuations within groups at all ages and were high in some animals by 21 wk. Unexpectedly, no correlation between pituitary bioCG and serum testosterone or ITAs was found, but these parameters significantly correlated with testicular weight and volume. These observations were consistent a dependence on the testis growth on bioCG. Unfortunately, the low serum levels of bioCG were not measurable in this study. At 43 wk, the animals reached puberty. At 52 wk of age, animals attained maximum body and epididymal weights and qualitatively normal spermatogenesis, but testes continued growing, reaching a maximum of all parameters at 70 wk of age, without further major changes at the age of 116 wk. It is concluded that (1) gonadal activation is evident at wk 21, (2) the male marmoset reaches the pubertal threshold around 43 wk of age, attains qualitative parameters at 52 wk, matures further to sexual maturity at 70 wk, and (3) serum testosterone and ITAs are highly variable without any identifiable correlation with pituitary bioCG.     

Zur Radikalischen Copolymerisation ungesättigter Isocyanate mit Vinylchlorid

On the Free Radical Copolymerization of Unsaturated Isocyanates with Vinylchloride The free radical copolymerization of vinyl-, isopropenyl- and p-vinyl-phenylisocyanate with vinylchloride in mass and tetrahydrofurane solution at 50°C is investigated. The incorporation of the isocyanate monomers in the copolymers is favoured. These monomers effect a great decrease of the rate of copolymerization and a crosslinking of the formed homo- and copolymers, whose extent depends on the kind and the quantity of the incorporated monomers. The crosslinking is caused by the forming of isocyanurate units.     

Variational optical flow computation in real time.

This paper investigates the usefulness of bidirectional multigrid methods for variational optical flow computations. Although these numerical schemes are among the fastest methods for solving equation systems, they are rarely applied in the field of computer vision. We demonstrate how to employ those numerical methods for the treatment of variational optical flow formulations and show that the efficiency of this approach even allows for real-time performance on standard PCs. As a representative for variational optic flow methods, we consider the recently introduced combined local-global method. It can be considered as a noise-robust generalization of the Horn and Schunck technique. We present a decoupled, as well as a coupled, version of the classical Gauss-Seidel solver, and we develop several multgrid implementations based on a discretization coarse grid approximation. In contrast, with standard bidirectional multigrid algorithms, we take advantage of intergrid transfer operators that allow for nondyadic grid hierarchies. As a consequence, no restrictions concerning the image size or the number of traversed levels have to be imposed. In the experimental section, we juxtapose the developed multigrid schemes and demonstrate their superior performance when compared to unidirectional multgrid methods and nonhierachical solvers. For the well-known 316 x 252 Yosemite sequence, we succeeded in computing the complete set of dense flow fields in three quarters of a second on a 3.06-GHz Pentium4 PC. This corresponds to a frame rate of 18 flow fields per second which outperforms the widely-used Gauss-Seidel method by almost three orders of magnitude.     

2‐(1‐Ethynylpyrene)‐Adenosine as a Folding Probe for RNA—Pyrene in or out

A series of short RNA duplexes containing one or two 1‐ethynylpyrene‐modified adenine bases was synthesised. The melting behaviour of these duplexes was examined by monitoring temperature‐dependent pyrene fluorescence. In the singly modified RNA duplexes, the bases flanking the ethynylpyrene‐rA were varied to examine the sequence specificity of the fluorescence change of pyrene upon RNA hybridisation. Because an increase in pyrene fluorescence upon melting of the duplex can be correlated with intercalation of pyrene, and a decrease is usually associated with the position of pyrene outside the strand, a relationship between the flanking bases and the tendency of the dye to intercalate has been established. It was found that pyrene intercalation is less likely to take place if the modified base is flanked only by A–U base pairs. Flanking G–C base pairs, even only in the 5′‐direction of the modified base, will favour intercalation. In addition, we examined a doubly modified compound that had a pyrene located on each strand. The spectra indicated that the two pyrenes were close enough for interaction. Upon melting of the strand, a fluorescence blue shift corresponding to the dissociation of the pyrene–pyrene complex could be observed in addition to the intensity effect already known from the singly modified compounds. Two melting curves based on the different properties of the fluorophore could be extracted, leading to different melting points corresponding to the global duplex melting and to the change of local pyrene environment, respectively.     

Blends of Two Perylene Derivatives: Mesogenic Properties and Application As Emitter Materials in OLEDs

Blends consisting of two components, namely a liquid crystalline perylene ester and a bilaterally extended perylene ester, were studied. The liquid crystalline properties of these blends were investigated in detail by means of polarized optical microscopy and differential scanning calorimetry. The resulting phase diagram was used to explore the potential of these blends as emitter layers in OLEDs, which were prepared via thermal evaporation in a vacuum and spin coating of solutions.     

Proton Conduction in Dense and Porous Nanocrystalline Ceria Thin Films

The electrical conductivity of ceria thin films (epitaxial as well as dense and porous nanocrystalline) is investigated in dry and wet atmosphere at temperatures below 500 °C. For the epitaxial and the fully dense nanocrystalline samples, no significant differences can be observed between dry and wet conditions. In marked contrast, the nanocrystalline porous films obtained via spin coating exhibit a considerable enhancement of the protonic conductivity below 300 °C in wet atmosphere. This outcome reveals that the residual open mesoporosity plays the key role for the enhancement of the proton transport at low temperatures and not the high density of grain boundaries. The quantitative analysis of the various pathways, along which the proton transport can take place, indicates that the observed proton conduction can arise not only from bulk water adsorbed in the open pores but also from the space charge zones on the water side of the water/oxide interface.