Surface sensitive study to determine the reactivity of soot with the focus on the European emission standards IV and VI

Diesel soot (Euro IV and Euro VI) was investigated with spectroscopic methods such as near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoemission spectroscopy (XPS). C and O K-edge NEXAFS show that structural disorder on the surface is accompanied by a higher amount of oxygen functional groups. O K-edge NEXAFS and O1s XPS results are discussed with the aim to elucidate the nature of the oxygen surface species. The analysis of the data presented here allows the postulation of a hypothetical structure for soot samples emitted by diesel engines.     

Cancer-Cell-Specific Drug Delivery by a Tumor-Homing CPP-Gossypol Conjugate Employing a Tracelessly Cleavable Linker

Tumor-targeted drug delivery is highly important for improving chemotherapy, as it reduces the dose of cytotoxic agents and minimizes the death of healthy tissues. Towards this goal, a conjugate was synthesized of gossypol and a MCF-7 cancer cell specific CPP (cell penetrating peptide), thus providing a selective drug delivery system. Utilizing the aldehyde moiety of gossypol, the tumor homing CPP RLYMRYYSPTTRRYG was attached through a semi-labile imine linker, which was cleaved in a traceless fashion under aqueous conditions and had a half-life of approximately 10 hours. The conjugate killed MCF-7 cells to a significantly greater extent than HeLa cells or healthy fibroblasts.     

A Supramolecular Stabilizer of the 14-3-3ζ/ERα Protein-Protein Interaction with a Synergistic Mode of Action

We report on a stabilizer of the interaction between 14-3-3ζ and the Estrogen Receptor alpha (ERα). ERα is a driver in the majority of breast cancers and 14-3-3 proteins are negative regulators of this nuclear receptor, making the stabilization of this protein-protein interaction (PPI) an interesting strategy. The stabilizer ( 1 ) consists of three symmetric peptidic arms containing an arginine mimetic, previously described as the GCP motif. 1 stabilizes the 14-3-3ζ/ERα interaction synergistically with the natural product Fusicoccin-A and was thus hypothesized to bind to a different site. This is supported by computational analysis of 1 binding to the binary complex of 14-3-3 and an ERα-derived phosphopeptide. Furthermore, 1 shows selectivity towards 14-3-3ζ/ERα interaction over other 14-3-3 client-derived phosphomotifs. These data provide a solid support of a new binding mode for a supramolecular 14-3-3ζ/ERα PPI stabilizer.     

A flow-through microarray cell for the online SERS detection of antibody-captured E. coli bacteria

We present an immunoassay microarray flow-through system for the surface-enhanced Raman scattering (SERS) analysis of bacteria. The system has been constructed to support and automatize the nondestructive in situ analysis of different microorganisms in aqueous environment. After the immobilization of the desired antibodies to an activated PEG-coated surface, the chip is placed into the flow cell which is then flushed with the contaminated sample. Finally, colloidal metal nanoparticles are added and the cells are detected label-free by SERS. Here, we introduce the successful imaging of single microorganisms in the flow cell as well as the quantification of microorganisms in water by SERS mapping with a linear range between 4.3 × 10³ to 4.3 × 10⁵ cells/mL. The method has potential for routine application, e.g. for drinking water control.     

Fullerene/liquid crystal mixtures as QMB- and SAW-coatings – detection of diesel- and solvent-vapours

The detection of diesel fuel and different solvent vapours in air is described. Due to the very low vapour pressure of diesel fuel, highly mass sensitive quartz microbalance (QMB) and surface acoustic wave (SAW) sensors are used. Micro porous coatings are presented consisting of liquid crystals and buckminster fullerenes. Thereby the globular compound disturbs the structure of the rod-like component and cavities and channels are created. With these mixtures it is possible to attain a resolution of 0.5% of the vapour pressure of diesel in air with the QMB; an even fivefold increase of sensitivity can be obtained with highly sensitive SAW devices operating at 433 MHz. In the latter case alkylsilane monolayers are used to promote adhesion, which themselves show a similar sensitivity as the QMB, but with an instantaneous response. Received: 25 September 1995 / Revised: 7 February 1996 / Accepted: 10 February 1996     

Photochromism of O-Analogs of Thiathiophthenes

Irradiation of O-analogs of thiathiophthenes yield a photoproduct which reverts thermally to the starting material. Kinetic measurements for this thermal reaction yield E_a values in the range of 10–15 kcal/mol and Δ S* values between ?16 and ?41 eu. Based on NMR. and IR. results the structure of the photoproduct is established. The electronic spectra of the starting material and of the photoproduct are discussed. The experimental results are compared with MO-calculations.     

The12C(2 1 + ) state as probe for transient magnetic fields in polarized iron

PAC measurements on the 4.43 MeV¹²C(2⁺) state on recoil in magnetized iron at velocitiesv _ion=2.1v ₀, 6.0v ₀, 7.4v ₀ yield integral precession angles of =+0.72(18), +0.94(16) and +0.71(18) mrad, respectively. The results supplementary to existing precession data are interpreted by a distribution of C⁵⁺ ions implying a K-shell polarization of 28% and an effective charge larger than measured after emergence from the solid. The low-velocity precession tends to disagree with the empirical law of linear relationship between transient field and ion velocity. The presence of molecular orbital effects is discussed.