Triplet-singlet conversion in ultracold Cs2_2 and production of ground state molecules

We propose a process to convert ultracold metastable Cs$_2$ molecules in their lowest triplet state into (singlet) ground state molecules in their lowest vibrational levels. Molecules are first pumped into an excited triplet state, and the triplet-singlet conversion is facilitated by a two-step spontaneous decay through the coupled $A^{1}\Sigma_{u}^{+} \sim b ^{3}\Pi_{u}$ states. Using spectroscopic data and accurate quantum chemistry calculations for Cs$_2$ potential curves and transition dipole moments, we show that this process has a high rate and competes favorably with the single-photon decay back to the lowest triplet state. In addition, we demonstrate that this conversion process represents a loss channel for vibrational cooling of metastable triplet molecules, preventing an efficient optical pumping cycle down to low vibrational levels

Assays for mitotic chromosome condensation in live yeast and mammalian cells

The dynamic reorganization of chromatin into rigid and compact mitotic chromosomes is of fundamental importance for faithful chromosome segregation. Owing to the difficulty of investigating this process under physiological conditions, the exact morphological transitions and the molecular machinery driving chromosome condensation remain poorly defined. Here, we review how imaging-based methods can be used to quantitate chromosome condensation in vivo, focusing on yeast and animal tissue culture cells as widely used model systems. We discuss approaches how to address structural dynamics of condensing chromosomes and chromosome segments, as well as to probe for mechanical properties of mitotic chromosomes. Application of such methods to systematic perturbation studies will provide a means to reveal the molecular networks underlying the regulation of mitotic chromosome condensatio

Parallel ion strings in linear multipole traps

Additional radio-frequency (rf) potentials applied to linear multipole traps create extra field nodes in the radial plane which allow one to confine single ions, or strings of ions, in totally rf field-free regions. The number of nodes depends on the order of the applied multipole potentials and their relative distance can be easily tuned by the amplitude variation of the applied voltages. Simulations using molecular dynamics show that strings of ions can be laser cooled down to the Doppler limit in all directions of space. Once cooled, organized systems can be moved with very limited heating, even if the cooling process is turned off

Preparing of Grätzel solar cell

Bakalárska práca rieši problematiku farbivami senzibilizovaných solárnych článkov. Práca uvádza princíp fungovania týchto článkov. Ďalej rozoberá použitie rôznych typov farbív, protielektród, elektrolytov a vodivých skiel. Práca obsahuje tiež princípy merania účinnosti solárnych článkov. V práci sa tiež rozoberá spôsob výroby daných článkov. Praktická časť je zameraná na výrobu prototypov článkov a meranie ich parametrov.This bachelor thesis focuses on the problematic of the dye-sensitized solar cells. The thesis states the working principle of these cells. It also deals with the use of different types of dyes, counterelectrodes, electrolytes and conducting glass. The thesis also contains the principles used in measuring the effectivity of solar cells. The manufacturing process of these cells is described in this thesis. The practical part of the thesis is focused on the manufacture of cell prototypes and the measuring of their parameters.

Control of DC Servo Drive

Tato práce pojednává o návrhu kaskádního řízení servomechanismu se stejnosměrným motorem. Je zde řešen návrh jednotlivých regulátorů tedy regulátoru polohy, otáček a proudu. Dále se zabývá implementací algoritmů PS a PSD regulátoru na mikroprocesoru.This work deals with the proposal of cascade control of the DC servo motor. This work solve proposal of position regulators, angular velocity regulators and current regulators. Futhermore this work deals with the implementation of an algorithms of discrete PI and PID regulators on microprocessor.

Photodetachment of cold OH- in a multipole ion trap

The absolute photodetachment cross section of OH- anions at a rotational and translational temperature of 170K is determined by measuring the detachment-induced decay rate of the anions in a multipole radio-frequency ion trap. In comparison with previous results, the obtained cross section shows the importance of the initial rotational state distribution. Using a tomography scan of the photodetachment laser through the trapped ion cloud, the derived cross section is model-independent and thus features a small systematic uncertainty. The tomography also yields the column density of the OH- anions in the 22-pole ion trap in good agreement with the expected trapping potential of a large field free region bound by steep potential walls.Comment: Phys. Rev. Lett., in pres

Near- and Mid-IR Gas-Phase Absorption Spectra of H2@C60+-He

Near- and mid-IR absorption spectra of endohedral H2@C60+ have been measured using He-tagging. The samples have been prepared using a 'molecular surgery' synthetic approach and were ionized and spectroscopically characterized in the gas phase. In contrast to neutral C60 and H2@C60, the corresponding He-tagged cationic species show distinct spectral differences. Shifts and line splittings in the near- and mid-IR regions indicate the influence of the caged hydrogen molecule on both the electronic ground and excited states. Possible relevance to astronomy is discussed

Kinetic framework of spindle assembly checkpoint signaling

Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Cell Biology 15 (2013): 1370-1377, doi:10.1038/ncb2842.The mitotic spindle assembly checkpoint (SAC) delays anaphase onset until all chromosomes have attached to both spindle poles1, 2. Here, we investigated SAC signaling kinetics in response to acute detachment of individual chromosomes using laser microsurgery. Most detached chromosomes delayed anaphase until they had realigned to the metaphase plate. A substantial fraction of cells, however, entered anaphase in the presence of unaligned chromosomes. We identify two mechanisms by which cells can bypass the SAC: First, single unattached chromosomes inhibit the anaphase promoting complex/cyclosome (APC/C) less efficiently than a full complement of unattached chromosomes. Second, because of the relatively slow kinetics of reimposing APC/C inhibition during metaphase, cells were unresponsive to chromosome detachment up to several minutes before anaphase onset. Our study defines when cells irreversibly commit to enter anaphase and shows that the SAC signal strength correlates with the number of unattached chromosomes. Detailed knowledge about SAC signaling kinetics is important for understanding the emergence of aneuploidy and the response of cancer cells to chemotherapeutics targeting the mitotic spindle.Research in the Gerlich laboratory has received funding from the European Community’s Seventh Framework Programme FP7/2007-2013 under grant agreements n° 241548 (MitoSys) and n° 258068 (Systems Microscopy), from an ERC Starting Grant (agreement n° 281198), from the EMBO Young Investigator Programme, from the Swiss National Science Foundation, from the Austrian Science Fund (FWF)-funded project “SFB Chromosome Dynamics”, and from a Summer Research Award of the Marine Biology Laboratory Woods Hole (Laura and Arthur Colwin Endowed Summer Research Fellowship Fund). A.E.D. is a fellow of the Zurich Ph.D. Program in Molecular Life Sciences and has received funding from a PhD fellowship by the Boehringer Ingelheim Fonds and from a Peter Müller fellowship.2014-04-0