Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Hardness conserving semilocal pseudopotentials

Abstract: A new type of pseudopotentials for local orbital methods is presented. Hardness conserving semilocal pseudopotentials have been generated for all elements from H to Am. The construction is based on a minimization of errors with the norm conservation conditions for 2--3 relevant ionic configurations of the atom. Besides the transferability between atomic states, the portability among density functionals is also of interest. This paper explores if the norm-conservation errors can be kept reasonably small when minimized for two functionals, e.g., the generalized gradient approximation (GGA) and local density approximation, simultaneously. It is found that the errors can be kept at roughly the same low level as for a single functional. Since these pseudopotentials are mainly designed for use with local orbital methods, semicore functions may be treated as valence functions, helping to increase the accuracy and portability. Therefore the name density functional semicore pseudopotential or DSPP is suggested. To further improve portability and, importantly, also aid numerical stability with GGA's, a core density (nonlinear core correction) is used. As with other pseudopotentials, scalar relativistic corrections to atomic scattering properties can easily be incorporated into this PP. Finally performance DSPP's versus all electron DSPP's with the same method, will be shown for an extensive set of test calculations. It is found that the DSPP is a very well behaved pseudo-potential.

Molecular signatures of G-protein-coupled receptors.

Abstract: G-protein-coupled receptors (GPCRs) are physiologically important membrane proteins that sense signalling molecules such as hormones and neurotransmitters, and are the targets of several prescribed drugs. Recent exciting developments are providing unprecedented insights into the structure and function of several medically important GPCRs. Here, through a systematic analysis of high-resolution GPCR structures, we uncover a conserved network of non-covalent contacts that defines the GPCR fold. Furthermore, our comparative analysis reveals characteristic features of ligand binding and conformational changes during receptor activation. A holistic understanding that integrates molecular and systems biology of GPCRs holds promise for new therapeutics and personalized medicine.

Highly multiplexed imaging of tumor tissues with subcellular resolution by mass cytometry

Abstract: Mass cytometry enables high-dimensional, single-cell analysis of cell type and state. In mass cytometry, rare earth metals are used as reporters on antibodies. Analysis of metal abundances using the mass cytometer allows determination of marker expression in individual cells. Mass cytometry has previously been applied only to cell suspensions. To gain spatial information, we have coupled immunohistochemical and immunocytochemical methods with high-resolution laser ablation to CyTOF mass cytometry. This approach enables the simultaneous imaging of 32 proteins and protein modifications at subcellular resolution; with the availability of additional isotopes, measurement of over 100 markers will be possible. We applied imaging mass cytometry to human breast cancer samples, allowing delineation of cell subpopulations and cell-cell interactions and highlighting tumor heterogeneity. Imaging mass cytometry complements existing imaging approaches. It will enable basic studies of tissue heterogeneity and function and support the transition of medicine toward individualized molecularly targeted diagnosis and therapies.

X-ray phase imaging with a grating interferometer.

Abstract: Using a high-efficiency grating interferometer for hard X rays (10-30 keV) and a phase-stepping technique, separate radiographs of the phase and absorption profiles of bulk samples can be obtained from a single set of measurements. Tomographic reconstruction yields quantitative three-dimensional maps of the X-ray refractive index, with a spatial resolution down to a few microns. The method is mechanically robust, requires little spatial coherence and monochromaticity, and can be scaled up to large fields of view, with a detector of correspondingly moderate spatial resolution. These are important prerequisites for use with laboratory X-ray sources.

High-flux solar-driven thermochemical dissociation of CO2 and H2O using nonstoichiometric ceria

Abstract: Because solar energy is available in large excess relative to current rates of energy consumption, effective conversion of this renewable yet intermittent resource into a transportable and dispatchable chemical fuel may ensure the goal of a sustainable energy future. However, low conversion efficiencies, particularly with CO_2 reduction, as well as utilization of precious materials have limited the practical generation of solar fuels. By using a solar cavity-receiver reactor, we combined the oxygen uptake and release capacity of cerium oxide and facile catalysis at elevated temperatures to thermochemically dissociate CO_2 and H_2O, yielding CO and H_2, respectively. Stable and rapid generation of fuel was demonstrated over 500 cycles. Solar-to-fuel efficiencies of 0.7 to 0.8% were achieved and shown to be largely limited by the system scale and design rather than by chemistry.