STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface

We characterize the incorporation of Ba adatoms into the Ge(001) surface, resulting in the formation of one-dimensional structures with an internal 2×3 periodicity, after the deposition of Ba atoms at 970 K or at room temperature followed by a 770 K anneal. Scanning tunneling microscopy (STM) data were compared with theoretically simulated STM images generated by density functional theory electronic structure calculations. Excellent agreement between experiment and simulation was found when using an adopted structural model that assumes partial removal of the surface Ge dimers in the [1–10] surface direction and subsequent addition of a single Ba atom to the substrate second layer. Structural assignments for a number of defects observed within regions of the 2×3 reconstruction were also obtained

Initial growth of Ba on Ge(001): An STM and DFT study

An ordered alkaline-earth submonolayer on a clean Si(001) surface provides a template for growth of the atomically sharp, crystalline Si-oxide interface that is ubiquitous in the semiconductor device industry. It has been suggested that submonolayers of Sr or Ba on Ge(001) could play a similar role as on structurally identical Si(001), overcoming known limitations of the Ge(001) substrate such as amorphization of its oxidation layers. In this paper the initial stage of the Ba oxidation process, i.e., adsorption and organization of Ba atoms on the Ge(001) surface as a function of temperature (270−770 K) for coverage 1.0 monolayer (ML) and 0.15−0.4 ML, is studied using scanning tunneling microscopy (STM) and density functional theory (DFT). Three types of features have been identified on the Ba-covered Ge(001) surface. They originate from isolated Ba adatoms, isolated Ba ad-dimers, and the Ba ad-dimers assembled into short-range, randomly distributed chains that run across the Ge dimer rows. We find from both STM measurements and DFT calculations that the latter is the dominant structure on Ge(001) with increasing coverage

Higher order reconstructions of the Ge(001) surface induced by a Ba layer

Structural properties of Ba-induced reconstructions on a Ge(001) surface, based on atomic-resolution ultra high-vacuum scanning tunneling microscopy measurements, are discussed. It is shown that while the Ba - Ge layer, which fully covers the surface, is dominated by a phase with an internal 2 × 3 periodicity, it also includes portions of higher order 2 × 6 and 4 × 3 surface reconstructions, always accompanied by 1D protrusions embedded into the dominating phase. Modelling the observed higher order structures, using the elementary cell of the 2 × 3 phase calculated within the density functional theory, is shown to reproduce the experimental data very well. As such the higher order reconstructions can be treated as local defects of the dominating 2 × 3 phase

HMGXB4 targets Sleeping Beauty transposition to vertebrate germinal stem sells

Transposons are parasitic genetic elements that frequently hijack key cellular processes of the host. HMGXB4 is a Wnt signalling-associated HMG-box protein, previously identified as a transcriptional regulating host factor of Sleeping Beauty (SB) transposition. Here, we establish that HMGXB4 is highly expressed from the zygote stage, and declines after transcriptional genome activation. Nevertheless, HMGXB4 is activated by its own promoter at 4-cell stage, responding to the parental-to-zygotic transition, marks stemness, and maintains its expression during germ cell specification. The HMGXB4 promoter is located at an active chromatin domain boundary. As a vertebrate-specific modulator of SETD1A and NuRF complexes, HMGXB4 links histone H3K4 methyltransferase- and ATP-dependent nucleosome remodelling activities. The expression of HMGXB4 is regulated by the KRAB-ZNF/TRIM28 epigenetic repression machinery. A post-transcriptional modification by SUMOylation diminishes its transcriptional activator function and regulates its nucleolar trafficking. Collectively, HMGXB4 positions SB transposition into an elaborate stem cell-specific transcriptional regulatory mechanism that is active during early embryogenesis and germline development, thereby potentiating heritable transposon insertions in the germline

Silicon Mie Resonators for Highly Directional Light Emission from monolayer MoS2

Controlling light emission from quantum emitters has important applications ranging from solid-state lighting and displays to nanoscale single-photon sources. Optical antennas have emerged as promising tools to achieve such control right at the location of the emitter, without the need for bulky, external optics. Semiconductor nanoantennas are particularly practical for this purpose because simple geometries, such as wires and spheres, support multiple, degenerate optical resonances. Here, we start by modifying Mie scattering theory developed for plane wave illumination to describe scattering of dipole emission. We then use this theory and experiments to demonstrate several pathways to achieve control over the directionality, polarization state, and spectral emission that rely on a coherent coupling of an emitting dipole to optical resonances of a Si nanowire. A forward-to-backward ratio of 20 was demonstrated for the electric dipole emission at 680 nm from a monolayer MoS2 by optically coupling it to a Si nanowire

Social times, reproduction and social inequality at work : contrasts and comparative perspectives between countries

Production of INCASI Project H2020-MSCA-RISE-2015 GA 691004If the focus is placed specifically on the problem of work and family, the daily life of people and their use of time are a main problem. This time is expressed in both freely available time, which is related to activities, and time of the productive and reproductive sphere. This chapter considers work in a broad sense and takes into account the sexual division of labour. Specifically, this chapter will explore transformations in time use and social inequality in unpaid work. For this purpose, a comparative analysis of time-use surveys will be used, analysing the time spent, and the time dedicated to household chores in Chile, Argentina, Uruguay and Spain. From an analytical viewpoint, the analysis will place social reproduction at the centre of the socio-economic system, showing that the economic crisis has affected women and men differently, and that in both Europe and Latin America the family pattern is being replaced by a dominant family model of a male provider and a double presence of women. The large-scale incorporation of women into the labour market has emphasised the role that women assume in the domestic sphere perpetuating gender segregation in employment and in domestic and care work

Matrix metalloproteinases in the wound microenvironment: therapeutic perspectives

Alicja Krejner,1 Malgorzata Litwiniuk,1–3 Tomasz Grzela11Laboratory of Cell Molecular Biology, Department of Histology and Embryology, Biostructure Research Center, Medical University of Warsaw, Warsaw, Poland; 2Postgraduate School of Molecular Medicine, Medical University of Warsaw, Warsaw, Poland; 3Department of Otolaryngology, Medical University of Warsaw, Warsaw, PolandAbstract: Matrix metalloproteinases (MMPs) are key effector molecules responsible for extracellular matrix (ECM) turnover. They are involved in tissue remodeling and regeneration. Although the main targets for MMPs are ECM components, they are also able to digest a variety of non-ECM molecules including cytokines, their receptors, or carriers. Therefore, the activity of the MMPs remains under tight control. However, when controlling mechanisms are ineffective, MMPs may become highly dangerous molecules, which have a strong destructive effect on affected tissues. Apart from cancer metastasis, aneurysm formation, or airway remodeling in asthma, MMPs have also been identified as main detrimental factors in delayed healing of chronic wounds. In this short review, we describe main representatives of MMPs family, their role in pathophysiology of chronic wounds, as well as current and possible therapeutic strategies for modulation of MMPs’ activity, which may be useful in management of chronic wounds.Keywords: chronic wound, MMPs, MMP inhibitors, wound treatmen

Occupational HIV risk for health care workers: risk factor and the risk of infection in the course of professional activities

Przemysław Wyżgowski,1 Anna Rosiek,2 Tomasz Grzela,1 Krzysztof Leksowski1,2 1Department of General Surgery, Military Hospital, 2Public Health Department, Faculty of Health Sciences, Nicolas Copernicus University in Toruń, Bydgoszcz, Poland Abstract: Virtually created panic among health care workers about pandemic acquired immune deficiency syndrome prompted us to review the scientific literature to investigate the risk of human immunodeficiency virus (HIV) transmission in the daily works of health care workers, especially surgeons and anesthesiologists. In this review, we report worldwide valuations of the number of HIV infections that may occur from unsafe daily work in health care. We also present how to minimize the risk of infection by taking precautions and how to utilize postexposure prophylaxis in accordance with the latest reports of the Centers for Disease Control and Prevention. HIV-infected patients will be aging, and most of them will become the candidates for procedures such as major vascular reconstruction and artery bypass grafting, where the risks of blood contact and staff injury are high. For these reasons, all health care workers need to know how to prevent, and fight following the accidental exposure to HIV. Keywords: HIV infection, risk factor, anesthesiologist, surgeon

Enhancing and directing light emission in semiconductor nanowires through leaky/guided modes

Santander (Spain), May 14-16 (2014); http://www.phantomsnet.net/cen2014/index.php?p=1Peer Reviewe