Trajectory surface hopping within linear response time-dependent density-functional theory

A fewest switches trajectory surface hopping algorithm based on linear response time-dependent density-functional theory is developed and implemented into the plane wave ab initio molecular dynamics package CPMD. A scheme to calculate nonadiabatic couplings using a multi determinantal approximation of the excited state wave function is introduced. The method is applied to the study of the photorelaxation of protonated formaldimine, a minimal model of the rhodopsin chromophore retinal. A good agreement of the structural and dynamic behavior is found with respect to state averaged multiconfiguration self consistent field based trajectory surface hopping.     

Controlled Light‐Mediated Preparation of Gold Nanoparticles by a Norrish Type I Reaction of Photoactive Polymers

Gold nanoparticles (AuNPs) are subjects of broad interest in scientific community due to their promising physicochemical properties. Herein we report the facile and controlled light‐mediated preparation of gold nanoparticles through a Norrish type I reaction of photoactive polymers. These carefully designed polymers act as reagents for the photochemical reduction of gold ions, as well as stabilizers for the in situ generated AuNPs. Manipulating the length and composition of the photoactive polymers allows for control of AuNP size. Nanoparticle diameter can be controlled from 1.5 nm to 9.6 nm.     

The Latin-American network of human genetics

The Latin-American Network of Human Genetics (RELAGH) is an internet-based federation of human and medical genetic societies of Latin America constituted in 2001. Member societies include the Mexican Association of Human Genetics, the Brazilian Society of Clinical Genetics, the Human Genetics Section of the Argentinean Society of Genetics, the Colombian Society of Human Genetics and the Panamanian Human Genetics Society. RELAGH is a full member of the steering committee of the International Federation of Human Genetics Societies. A core activity of RELAGH is to become a platform for the integration and collaboration of human geneticists across Latin America regarding training, services and research in medical genetics in the region.     

Azobenzene-containing triazatriangulenium adlayers on Au(111): structural and spectroscopic characterization

Adlayers of different azobenzene-functionalized derivatives of the triazatriangulenium (TATA) platform on Au(111) surfaces were studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), gap-mode surface-enhanced Raman spectroscopy (gap-mode SERS), and cyclic voltammetry (CV). The chemical composition of the adlayers is in good agreement with the molecular structure, i.e., different chemical groups attached to the azobenzene functionality were identified. Furthermore, the presence of the azobenzene moieties in the adlayers was verified by the vibration spectra and electrochemical data. These results indicate that the molecules remain intact upon adsorption with the freestanding functional groups oriented perpendicularly to the TATA platform and thus also to the substrate surface.     

Micro-homogeneity studies of boron carbide powders

We have studied the micro-homogeneity of boron carbide powders by inductively coupled plasma optical emission spectrometry (ICP-OES) and total reflection X-ray fluorescence spectrometry (TXRF) using slurry sampling. To get information on the particle size distributions of the powders, the stabilized slurries of boron carbide powders were nebulized, the aerosols were transported into a Batelle impactor and the droplets were collected on the impactor stages bearing TXRF sample holders. In a first series of measurements, parameters of the impaction like the duration of the impaction and the use of glutinous substance on the sample holders were optimized. The different mass size fractions for industrial boron carbide powders were determined by weight measurements of the fractions collected on the different stages. The established particle size distributions were in the range of 0.5 to >16 μm and found similar to those determined by laser diffraction reported elsewhere. Analyses of the mass fractions by slurry sampling TXRF showed that Ca, Ti, Cr, Mn, Fe, Ni and Cu within the measurements errors were homogeneously distributed over the mass fractions between 0.5 and 4 μm and that their concentrations agreed with the bulk composition, as determined with ICP-OES subsequent to digestion. However, light underestimates were found at the 5 (Mn) up to 150 μg g^?1 (Fe) level. Finally, boron carbide powders were washed out with nitric acid with different concentrations and leaching solutions and the residues were analyzed by ICP-OES and TXRF respectively. It is shown that up to 60% of the residual trace impurities in the powder studied can be removed by leaching with 34% (v/v) of nitric acid.

Specific CLK inhibitors from a novel chemotype for regulation of alternative splicing

There is a growing recognition of the importance of protein kinases in the control of alternative splicing. To define the underlying regulatory mechanisms, highly selective inhibitors are needed. Here, we report the discovery and characterization of the dichloroindolyl enaminonitrile KH-CB19, a potent and highly specific inhibitor of the CDC2-like kinase isoforms 1 and 4 (CLK1/CLK4). Cocrystal structures of KH-CB19 with CLK1 and CLK3 revealed a non-ATP mimetic binding mode, conformational changes in helix αC and the phosphate binding loop and halogen bonding to the kinase hinge region. KH-CB19 effectively suppressed phosphorylation of SR (serine/arginine) proteins in cells, consistent with its expected mechanism of action. Chemical inhibition of CLK1/CLK4 generated a unique pattern of splicing factor dephosphorylation and had at low nM concentration a profound effect on splicing of the two tissue factor isoforms flTF (full-length TF) and asHTF (alternatively spliced human TF).     

Trajectory-based solution of the nonadiabatic quantum dynamics equations: an on-the-fly approach for molecular dynamics simulations

The non-relativistic quantum dynamics of nuclei and electrons is solved within the framework of quantum hydrodynamics using the adiabatic representation of the electronic states. An on-the-fly trajectory-based nonadiabatic molecular dynamics algorithm is derived, which is also able to capture nuclear quantum effects that are missing in the traditional trajectory surface hopping approach based on the independent trajectory approximation. The use of correlated trajectories produces quantum dynamics, which is in principle exact and computationally very efficient. The method is first tested on a series of model potentials and then applied to study the molecular collision of H with H(2) using on-the-fly TDDFT potential energy surfaces and nonadiabatic coupling vectors.