Amphiphilic Polyoxometalates for the Controlled Synthesis of Hybrid Polystyrene Particles with Surface Reactivity

Amphiphilic organo‐polyoxometalates (POMs) used in the radical emulsion polymerization of styrene allowed the preparation in aqueous medium of stable 50–100 nm polystyrene–POM composite latexes. Thanks to the presence of a trithiocarbonate group in the POM amphiphile, POMs could be covalently linked to the polymer particle surface. The chemical and catalytic integrity of the POMs was confirmed, and the POM‐mediated surface photoactivity of the latexes was demonstrated by the spatially controlled nucleation of silver nanoparticles at the periphery of the composites.     

Reaktionen von aminofluorosilanen zu vier- bis siebengliedrigen ringsystemen

The reaction of N,N′-dimethylurea, N,N′-dimethylethylenediamine and t-butylamine with fluorosilyl-substituted disilazanes leads after primary lithiation with butyllithium to the formation of the six, seven- and four-membered rings I–III. The five- and seven-membered rings IV and V were prepared in a comparable reaction with the disodium salt of ethyleneglycol.     

First-principles statistical mechanics study of the stability of a subnanometer thin surface oxide in reactive environments: CO oxidation at Pd(100)

We employ a multiscale modeling approach to study the surface structure and composition of a Pd(100) model catalyst in reactive environments. Under gas phase conditions representative of technological CO oxidation (approximately 1 atm, 300-600 K) we find the system on the verge of either stabilizing subnanometer thin oxide structures or CO adlayers at the surface. Under steady-state operation this suggests the presence or continuous formation and reduction of oxidic patches at the surface, which could be key to understand the observable catalytic function.     

Umsetzungen von Dilithio-nitroalkanen und -allylnitroderivaten mit Carbonylverbindungen

Reactions of dilithio-nitroalkanes and dilithio-allynitroalkanes with carbonyl compounds Primary nitro compounds can by acylated via dilithium derivatives 5 with carbonic-acid derivatives to give α-nitro esters 6a – i and with carboxylic-acid esters and anhydrides to give α-nitroketones 6j – q . In the reaction of 1-nitro-1-buten with two mol-equiv. of butyllithium, the dilithium compound 10 is formed by successive Michael-addition and nitronate deprotonation. Dilithium derivatives 5 also react with ketones and benzaldehyde (→ 18a – g ); the nitro aldols 25 and 26 are likewise formed by addition of doubly deprotonated allylic nitro compounds. Some of the products have been further transformed by reduction or by Nef-reactions to the hydrochloride of the α-amino-acid 26 , to 2-amino-alcohols 28a and 28b , to α-hydroxyamino-acid esters 27a – c , to α-hydroxyimino esters 35 and 36 , to α-hydroxyimino ketones 31 and 33 , to the α-diketone 34 , and to the α-keto ester 37 .     

Benzoylphosphonate-Based Photoactive Phosphopeptide Mimetics for Modulation of Protein Tyrosine Phosphatases and Highly Specific Labeling of SH2 Domains

A light switch for phosphotyrosine- recognizing proteins: Irradiation of the bioisosteric benzoylphosphonate suffices to "turn off" the activity of target proteins and to label them covalently. Photoactive bioisosters may find applications in functional cell biology, bioanalytics, and proteome research.     

MRI rotating frame relaxation measurements for articular cartilage assessment

In the present work we introduced two MRI rotating frame relaxation methods, namely adiabatic T_1ρ and Relaxation Along a Fictitious Field (RAFF), along with an inversion-prepared Magnetization Transfer (MT) protocol for assessment of articular cartilage. Given the inherent sensitivity of rotating frame relaxation methods to slow molecular motions that are relevant in cartilage, we hypothesized that adiabatic T_1ρ and RAFF would have higher sensitivity to articular cartilage degradation as compared to laboratory frame T₂ and MT. To test this hypothesis, a proteoglycan depletion model was used. Relaxation time measurements were performed at 0 and 48 h in 10 bovine patellar specimens, 5 of which were treated with trypsin and 5 untreated controls were stored under identical conditions in isotonic saline for 48 h. Relaxation times measured at 48 h were longer than those measured at 0 h in both groups. The changes in T₂ and MT relaxation times after 48 h were approximately 3 times larger in the trypsin treated specimens as compared to the untreated group, whereas increases of adiabatic T_1ρ and RAFF were 4 to 5 fold larger. Overall, these findings demonstrate a higher sensitivity of adiabatic T_1ρ and RAFF to the trypsin-induced changes in bovine patellar cartilage as compared to the commonly used T₂ and MT. Since adiabatic T_1ρ and RAFF are advantageous for human applications as compared to standard continuous-wave T_1ρ methods, adiabatic T_1ρ and RAFF are promising tools for assessing cartilage degradation in clinical settings.     

Electroweak sphalerons with spin and charge

We show that, at finite weak mixing angle the sphaleron solution of Weinberg–Salam theory can be endowed with angular momentum proportional to the electric charge. Carrying baryon number 1/2 these sphalerons with spin and charge may contribute to baryon number violating processes.     

Templated PISA: Driving Polymerization‐Induced Self‐Assembly towards Fibre Morphology

Dispersions of block copolymer fibres in water have many potential applications and can be obtained by polymerization‐induced self‐assembly (PISA), but only under very restricted experimental conditions. In order to enlarge this experimental window, we introduced a supramolecular moiety, a hydrogen‐bonded bis‐urea sticker, in the macromolecular reversible addition fragmentation chain transfer (RAFT) agent to drive the morphology of the nano‐objects produced by RAFT‐mediated PISA towards the fibre morphology. This novel concept is tested in the synthesis of a series of poly(N,N‐dimethylacrylamide)‐b‐poly(2‐methoxyethyl acrylate) (PDMAc‐b‐PMEA) diblock copolymers prepared by dispersion polymerization in water. The results prove that the introduction of the templating bis‐urea stickers into PISA greatly promotes the formation of fibres in a large experimental window.     

Syntactic learning by mere exposure - An ERP study in adult learners

Background  

Artificial language studies have revealed the remarkable ability of humans to extract syntactic structures from a continuous sound stream by mere exposure. However, it remains unclear whether the processes acquired in such tasks are comparable to those applied during normal language processing. The present study compares the ERPs to auditory processing of simple Italian sentences in native and non-native speakers after brief exposure to Italian sentences of a similar structure. The sentences contained a non-adjacent dependency between an auxiliary and the morphologically marked suffix of the verb. Participants were presented four alternating learning and testing phases. During learning phases only correct sentences were presented while during testing phases 50 percent of the sentences contained a grammatical violation.