Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

Theoretical Chemistr

Experimental evidence of rainbow trapping and Bloch oscillations of torsional waves in chirped metallic beams

[EN] The Bloch oscillations (BO) and the rainbow trapping (RT) are two apparently unrelated phenomena, the former arising in solid state physics and the latter in metamaterials. A Bloch oscillation, on the one hand, is a counter-intuitive effect in which electrons start to oscillate in a crystalline structure when a static electric field is applied. This effect has been observed not only in solid state physics but also in optical and acoustical structured systems since a static electric field can be mimicked by a chirped structure. The RT, on the other hand, is a phenomenon in which the speed of a wave packet is slowed down in a dielectric structure; different colors then arrive to different depths within the structure thus separating the colors also in time. Here we show experimentally the emergence of both phenomena studying the propagation of torsional waves in chirped metallic beams. Experiments are performed in three aluminum beams in which different structures were machined: one periodic and two chirped. For the smaller value of the chirping parameter the wave packets, with different central frequencies, are back-scattered at different positions inside the corrugated beam; the packets with higher central frequencies being the ones with larger penetration depths. This behavior represents the mechanical analogue of the rainbow trapping effect. This phenomenon is the precursor of the mechanical Bloch oscillations, which are here demonstrated for a larger value of the chirping parameter. It is observed that the oscillatory behavior observed at small values of the chirp parameter is rectified according to the penetration length of the wave packet.Work partially supported by DGAPA-UNAM under projects PAPIIT IN103115 and IN109318 and by CONACYT project 284096. A.A.L. acknowledges CONACYT for the support granted to pursue his Ph.D. studies. G. Baez received CONACYT's financial support. RAMS received support from DGAPA-UNAM under program PASPA. We thank M. Martinez, A. Martinez, V. Dominguez-Rocha, E. Flores and E. Sadurni for invaluable comments. F.C., A.C. and J.S-D. acknowledge the support by the Ministerio de Economa y Competitividad of the Spanish government, and the European Union FEDER through project TEC2014-53088-C3-1-R.Arreola-Lucas, A.; Baez, G.; Cervera Moreno, FS.; Climente Alarcón, A.; Mendez-Sanchez, R.; Sánchez-Dehesa Moreno-Cid, J. (2019). Experimental evidence of rainbow trapping and Bloch oscillations of torsional waves in chirped metallic beams. Scientific Reports. 9:1860-1872. https://doi.org/10.1038/s41598-018-37842-7S186018729Ascroft, N. W. & Mermin, N. D. Solid State Physics (Hold, Reinhart & Winston, 1972).Kadic, M., Buckmann, T., Schittny, R. & Wegener, M. Metamaterials beyond electromagnetism. Rep. Prog. Phys. 76, 126501 (2013).Cummer, S. A., Christensen, J. & Alù, A. 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Expression of neurochondrin in the developing and adult mouse brain.

Here we describe a detailed analysis of the expression of neurochondrin (ncdn) in the developing and adult mouse brain. Ncdn is first expressed in the hindbrain and spinal cord at embryonic day 10.5 (E10.5) followed by expression in the midbrain at E11.5. By E18 ncdn is also expressed in the diencephalon and telencephalon. However, strongest expression is still observed in the hindbrain. In adults, the expression in the forebrain is as strong as in the hindbrain. Ncdn is highly expressed in the hippocampus, piriform cortex, septum, amygdaloid complex, medial geniculate nucleus, inferior colliculus, cerebellar nuclei and the nuclei of the Vth, VIIth, and XIIth cranial nerves

HIV-1 replication in human immune cells is independent of TAR DNA binding Protein 43 (TDP-43) expression.

The TAR DNA binding protein (TDP-43) was originally identified as a host cell factor binding to the HIV-1 LTR and thereby suppressing HIV-1 transcription and gene expression (Ou et al., J.Virol. 1995, 69(6):3584). TDP-43 is a global regulator of transcription, can influence RNA metabolism in many different ways and is ubiquitously expressed. Thus, TDP-43 could be a major factor restricting HIV-1 replication at the level of LTR transcription and gene expression. These facts prompted us to revisit the role of TDP-43 for HIV-1 replication. We utilized established HIV-1 cell culture systems as well as primary cell models and performed a comprehensive analysis of TDP-43 function and investigated its putative impact on HIV-1 gene expression. In HIV-1 infected cells TDP-43 was neither degraded nor sequestered from the nucleus. Furthermore, TDP-43 overexpression as well as siRNA mediated knockdown did not affect HIV-1 gene expression and virus production in T cells and macrophages. In summary, our experiments argue against a restricting role of TDP-43 during HIV-1 replication in immune cells

Highly efficient targeted mutagenesis in mice using TALENs.

Targeted mouse mutants are instrumental for the analysis of gene function in health and disease. We recently provided proof-of-principle for the fast-track mutagenesis of the mouse genome, using transcription activator-like effector nucleases (TALENs) in one-cell embryos. Here we report a routine procedure for the efficient production of disease-related knockin and knockout mutants, using improved TALEN mRNAs that include a plasmid-coded poly(A) tail (TALEN-95A), circumventing the problematic in vitro polyadenylation step. To knock out the C9orf72 gene as a model of frontotemporal lobar degeneration, TALEN-95A mutagenesis induced sequence deletions in 41% of pups derived from microinjected embryos. Using TALENs together with mutagenic oligodeoxynucleotides, we introduced amyotrophic lateral sclerosis patient-derived missense mutations in the fused in sarcoma (Fus) gene at a rate of 6.8%. For the simple identification of TALEN-induced mutants and their progeny we validate high-resolution melt analysis (HRMA) of PCR products as a sensitive and universal genotyping tool. Furthermore, HRMA of off-target sites in mutant founder mice revealed no evidence for undesired TALEN-mediated processing of related genomic sequences. The combination of TALEN-95A mRNAs for enhanced mutagenesis and of HRMA for simplified genotyping enables the accelerated, routine production of new mouse models for the study of genetic disease mechanisms

Quantum resonance, Anderson localisation and selective rotational excitation in periodically kicked molecules

We show that molecules kicked periodically by laser pulses currently used in molecular alignment experiments allow to observe effects of the periodically kicked quantum rotor in a real rotational system. Among these effects are Anderson localisation in angular momentum and the scaling of the quantum resonance. Based on this, we propose a new scheme for selective molecular rotational excitation