Negative-mass exciton polaritons induced by dissipative light-matter coupling in an atomically thin semiconductor.

Dispersion engineering is a powerful and versatile tool that can vary the speed of light signals and induce negative-mass effects in the dynamics of particles and quasiparticles. Here, we show that dissipative coupling between bound electron-hole pairs (excitons) and photons in an optical microcavity can lead to the formation of exciton polaritons with an inverted dispersion of the lower polariton branch and hence, a negative mass. We perform direct measurements of the anomalous dispersion in atomically thin (monolayer) WS2 crystals embedded in planar microcavities and demonstrate that the propagation direction of the negative-mass polaritons is opposite to their momentum. Our study introduces the concept of non-Hermitian dispersion engineering for exciton polaritons and opens a pathway for realising new phases of quantum matter in a solid state.

Practical application of different enzymes immobilized on sepabeads.

The immobilization of an endoglucanase, benzoylformate decarboxylase (BFD) from Pseudomonas putida, as well as of lipase B from Candida antarctica (CALB) onto the carrier supports Sepabeads EC-EP, Sepabeads EC-EA, and Sepabeads EC-BU was accomplished. It is shown that via these immobilized biocatalysts the synthesis of both fine and bulk chemicals is possible. This is illustrated by the syntheses of polyglycerol esters and (S)-hydroxy phenyl propanone. The benefit of immobilization is illustrated by repetitive use in a bubble column reactor as well as in a stirred tank reactor. High stability of two biocatalysts was achieved and reusability up to eight times was demonstrated. The comparison of CALB immobilized on Sepabeads EC-EP to Novozym 435 shows similar activity.

[Protein expression of hMSH2 and hMLH1 in HNPCC: evaluation of a prescreening method]. / Untersuchung der Proteinexpression von hMSH2 und hMLH1 bei HNPCC: Evaluation einer Prescreening-Methode.

We show that immunohistochemistry for hMSH2 and hMLH1 is an easy and reproducible routine procedure. The interpretation of the staining results is unequivocal and investigator-independent. It is now necessary to validate the specificity and sensitivity of the method in a multicenter study with tumors of known mutations. As a consequence perhaps MIN testing may be replaced by immunohistochemistry as a first-line pretesting for HNPCC, reducing cost and time required.