Reactions of tBu2P–PLi–PtBu2 with [(Et3P)2MCl2] (M = Ni,Pd, Pt). Synthesis and Properties of [(1,2‐η‐tBu2P=P–PtBu2)M(PEt3)Cl] (M=Ni,Pd)

^tBu₂P–PLi–P^tBu₂·2THF reacts with [cis‐(Et₃P)₂MCl₂] (M = Ni, Pd) yielding [(1,2‐η‐^tBu₂P=P–P^tBu₂)Ni(PEt₃)Cl] and [(1,2‐η‐^tBu₂P=P–P^tBu2)Pd(PEt₃)Cl], respectively. ^tBu₂P– PLi–P^tBu₂ undergoes an oxidation process and the ^tBu₂P–P–P^tBu₂ ligand adopts in the products the structure of a side‐on bonded 1,1‐di‐tert‐butyl‐2‐(di‐tert‐butylphosphino)diphosphenium cation with a short P–P bond. Surprisingly, the reaction of ^tBu₂P–PLi–P^tBu₂·2THF with [cis‐(Et₃P)₂PtCl₂] does not yield [(1,2‐η‐^tBu₂P=P–P^tBu₂)Pt(PEt₃)Cl].     

Neue Dimethinmerocyaninfarbstoffe mit J-Aggregation in stark verdünnter Lösung

Novel Dimethinmerocyanine Dyes Performing J-Aggregation in Highly Diluted Solution A series of various novel long-chain alkyl-dimethinmerocyanine dyes containing sulfonate groups is obtained in high yield by modified condensation reactions of sulfoalkyl- or sulfophenylsubstituted methylene ketones. The dyes exhibit intense, red-shifted absorption bands (? up to 263 000) due to J-aggregation in DMSO/H₂O mixtures without addition of salt even at dye concentrations of 5 · 10^?8M. The influence of dye structure and medium on the aggregation tendency is investigated. Besides it is found that exchange of the cationic counterions does not affect J-aggregation.     

Cs4[La(NO3)6](NO3). HNO3: Das erste Salpetersäureaddukt eines ternären Alkali-Lanthanidnitrats

Cs₄[La(NO₃)₆](NO₃) · HNO₃: The First Nitric Acid Adduct of a Ternary Alkali Lanthanide Nitrate In the crystal structure of Cs₄[La(NO₃)₆](NO₃). HNO₃ (monoclinic, P2₁/c, Z = 2, a = 787.3(2); b = 1353.0(3); c = 1141.8(7) pm; β = 94,37(3)°) La³⁺ has a coordination number of twelve (six bidentate nitrate ligands). The structure may be viewed at as a layer structure: Layers of the composition [Cs(1)₄La₂(NO₃)₁₂]^2?, and [Cs(2)₄(NO₃)₂(HNO₃)₂]²⁺ are stacked alternatively in the [100] direction.     

Certification of contents of aromatic hydrocarbons in charcoal tubes – CRM 562

A Certified Reference Material (CRM) for determination of aromatic hydrocarbons in air was developed. The CRM 562 consists of aromatic hydrocarbons sorbed on charcoal in glass tubes. Initial feasibility studies established that a homogeneous and stable batch could be prepared. Three intercomparisons prior to the certification allowed the identification of various sources of error. Then, a batch of about 3000 tubes was charged and certified on the basis of analyses carried out in 15 European laboratories. The preparation of the reference material and the results of the certification exercise is described. An overview on the analytical techniques used and the quality control guidelines are also presented. The certified values are 15.0 ± 0.4 μg benzene, 147.3 ± 3.8 μg toluene, 96.4 ± 2.5 μg m-xylene and 93.0 ± 2.9 μg o-xylene per tube. This reference material is recommended for quality control of measurements in the field of occupational hygiene.     

Biomagnetic separation of Salmonella Typhimurium with high affine and specific ligand peptides isolated by phage display technique

Analyses of food-borne pathogens are of great importance in order to minimize the health risk for customers. Thus, very sensitive and rapid detection methods are required. Current conventional culture techniques are very time consuming. Modern immunoassays and biochemical analysis also require pre-enrichment steps resulting in a turnaround time of at least 24 h. Biomagnetic separation (BMS) is a promising more rapid method. In this study we describe the isolation of high affine and specific peptides from a phage-peptide library, which combined with BMS allows the detection of Salmonella spp. with a similar sensitivity as that of immunomagnetic separation using antibodies.     

Essential norm of the difference of weighted composition operators

We study differences of weighted composition operators between weighted Banach spaces H _ν ^∞ of analytic functions with weighted sup-norms and give an expression for the essential norm of these differences. We apply our result to estimate the essential norm of differences of composition operators acting on Bloch-type spaces. Authors’ addresses: Mikael Lindstr?m, Department of Mathematics, Abo Akademi University, FIN 20500 Abo, Finland; Elke Wolf, Mathematical Institute, University of Paderborn, D-33095 Paderborn, Germany     

The density condition and distinguishedness for weighted Fréchet spaces of holomorphic functions

We consider weighted Fréchet spaces of holomorphic functions which are defined as countable intersections of weighted Banach spaces of type H^∞. We study when these spaces have Stefan Heinrich's density condition and when they are distinguished.     

Why contextualists cannot know they are right: Self-refuting implications of contextualism

Conversational contextualism in epistemology is characterized by four main theses: 1. the indexicality of knowledge claims thesis; 2. the attributor contextualism thesis; 3. the conversational contextualism thesis, and 4. the main thesis of contextualism according to which a knowledge claim can be true in one context and false in another context in which more stringent standards for knowledge are operant. It is argued that these theses taken together generate problems for contextualism. In particular, it is shown that there is no context in which the contextualist can truthfully claim to know her theory is true. Since these results were obtained only with principles the contextualist cannot give up—like the principle of epistemic closure and the principle that knowledge implies truth—it seems that contextualism is in need of a thoroughgoing revision if it is to become a successful epistemic theory.