Europium doping of zincblende GaN by ion implantation

Eu was implanted into high quality cubic (zincblende) GaN (ZB-GaN) layers grown by molecular beam epitaxy. Detailed structural characterization before and after implantation was performed by x-ray diffraction (XRD) and Rutherford backscattering/channeling spectrometry. A low concentration ( direction, while a Ga substitutional site is observed for W-GaN:Eu. The implantation damage in ZB-GaN:Eu could partly be removed by thermal annealing, but an increase in the wurtzite phase fraction was observed at the same time. Cathodoluminescence, photoluminescence (PL), and PL excitation spectroscopy revealed several emission lines which can be attributed to distinct Eu-related optical centers in ZB-GaN and W-GaN inclusions

Massive rearrangements of cellular MicroRNA signatures are key drivers of hepatocyte dedifferentiation

Hepatocytes are dynamic cells that, upon injury, can alternate between nondividing differentiated and dedifferentiated proliferating states in vivo . However, in two‐dimensional cultures, primary human hepatocytes (PHHs) rapidly dedifferentiate, resulting in loss of hepatic functions that significantly limits their usefulness as an in vitro model of liver biology, liver diseases, as well as drug metabolism and toxicity. Thus, understanding the underlying mechanisms and stalling of the dedifferentiation process would be highly beneficial to establish more‐accurate and relevant long‐term in vitro hepatocyte models. Here, we present comprehensive analyses of whole proteome and transcriptome dynamics during the initiation of dedifferentiation during the first 24 hours of culture. We report that early major rearrangements of the noncoding transcriptome, hallmarked by increased expression of small nucleolar RNAs, long noncoding RNAs, microRNAs (miRNAs), and ribosomal genes, precede most changes in coding genes during dedifferentiation of PHHs, and we speculated that these modulations could drive the hepatic dedifferentiation process. To functionally test this hypothesis, we globally inhibited the miRNA machinery using two established chemically distinct compounds, acriflavine and poly‐l ‐lysine. These inhibition experiments resulted in a significantly impaired miRNA response and, most important, in a pronounced reduction in the down‐regulation of hepatic genes with importance for liver function. Thus, we provide strong evidence for the importance of noncoding RNAs, in particular, miRNAs, in hepatic dedifferentiation, which can aid the development of more‐efficient differentiation protocols for stem‐cell‐derived hepatocytes and broaden our understanding of the dynamic properties of hepatocytes with respect to liver regeneration. Conclusion: miRNAs are important drivers of hepatic dedifferentiation, and our results provide valuable information regarding the mechanisms behind liver regeneration and possibilities to inhibit dedifferentiation in vitro

Computational analysis of dispersive and nonlinear 2D materials by using a GS-FDTD method

In this paper, we propose a novel numerical method for modeling nanostructures containing dispersive and nonlinear two-dimensional (2D) materials, by incorporating a nonlinear generalized source (GS) into the finite-difference time-domain (FDTD) method. Starting from the expressions of nonlinear currents characterizing nonlinear processes in 2D materials, such as second- and third-harmonic generation, we prove that the nonlinear response of such nanostructures can be rigorously determined using two linear simulations. In the first simulation, one computes the linear response of the system upon its excitation by a pulsed incoming wave, whereas in the second one the system is excited by a nonlinear GS, which is determined by the linear near-field calculated in the first linear simulation. This new method is particularly suitable for the analysis of dispersive and nonlinear 2D materials, such as graphene and transition-metal dichalcogenides, chiefly because, unlike the case of most alternative approaches, it does not require the thickness of the 2D material. To investigate the accuracy of the proposed GS-FDTD method and illustrate its versatility, the linear and nonlinear responses of graphene gratings have been calculated and compared to results obtained using alternative methods. Importantly, the proposed GS-FDTD can be extended to three-dimensional bulk nonlinearities, rendering it a powerful tool for the design and analysis of more complicated nanodevices

Generalized source method for modeling nonlinear diffraction in planar periodic structures

We present a new numerical method for the analysis of second-harmonic generation (SHG) in one-and twodimensional (1D, 2D) diffraction gratings with arbitrary profile made of non-centrosymmetric optical materials. Our method extends the generalized source method (GSM), which is a highly efficient alternative to the conventional Fourier modal method, to quadratically nonlinear diffraction gratings. The proposed method consists of a two-stage algorithm. Initially, the electromagnetic field at the fundamental frequency is computed in order to obtain the second-harmonic polarization using the known second-order nonlinear susceptibility. Then the optical field at the second-harmonic frequency is computed using this polarization as an additional source term in the GSM. We show how to integrate this source term into the GSM framework without changing the structure of the basic algorithm. We use the proposed algorithm to investigate a doubly resonant mechanism that leads to strong enhancement of SHG in a nonlinear 2D circular GaAs grating mounted on top of a GaAs slab waveguide. We design this optical device such that slab waveguide modes at the fundamental and second-harmonic are simultaneously excited and phase matched by the grating. The numerically obtained resonance frequencies show good agreement with analytically computed resonance frequencies of the unperturbed slab waveguide. © 2014 SPIE

Intra/ Sections:Post-Anthropocentric Concepts of Multiplicity

The DFG-Network ‘Dispositiv der Menge’ (= crowd, mass, multitude) is based on the recognition that ‘the crowd’ has been constituted, classified, regulated, or dispersed throughout history in various, heterogenous, conflictual ways, which make it impossible to hold onto any understanding of the crowd as a clearly delimited and substantiated entity or to the forms in which it is represented as such. This workshop extends this approach by taking ‘the crowd’ itself as a multitude or multiplicity. It will address phenomena related to more fluctuating and in/determinate intra/sections of collectivities in order to transform the image of ‘the crowd’ from an in-divi-dual-ized One into a mani-fold multiplicity. Such a multiplicity in the singular plural is characterized by movement and motion, fragmentation and friction, ongoingness and inherent contestation. By focusing on this multiplicity, the workshop seeks to un-work a persistent conceptual anthropocentrism of the ways in which agentiality is conceptualized and imagined, instead searching for more dynamic relations with/in a variety of agencies (human, animal, plant, things, propositions) that can be seen as ‘intra-active’. Yet, while ‘the crowd’ will be approached from a critique of anthropomorphism, the turn towards ecological or relational co-existence cannot be a turn away from the violent asymmetrical relations of power and the continued flexibilization and hierarchical re- ordering of global social structures. The workshop sounds out conceptual and phenomenal resonances between what in Western academic discourses has of late become known as ‘New Materialism’ (in its different strands) and the long tradition of (but also always newly emerging) indigenous and decolonial epistemologies. The idea is to look for ways to concretize the potential for intra/sections in-between posthuman(ist) and indigenous/decolonial thought-practices, hoping for a dialogue between more Western-oriented approaches — e.g., actor-network theory (Bruno Latour), the figures of the cyborg and companion species (Donna Haraway), vital materialism (Jane Bennett), un/limited ecologies (Vicky Kirby), or agential realism (Karen Barad) — and alternative indigenous cosmologies and ethical praxes such as ‘buen vivir/sumac kawsay’ (Alberto Acosta/Eduardo Gudynas), Amerindian perspectivalism (Eduardo Viveiros de Castro) or shape-shifting border/lands (Anzaldúa). The workshop invites its participants to diffract heterogeneous ways of thinking and enacting multiplicity. Collecting insights from literary and cultural studies, natural sciences, sociology, non-western cosmologies, or religion, it hopes to produce a vision of how a post- anthropocentric perspective can enrich an understanding of ‘world’ as a plurivocal worlding process.Intra/ Sections: Post-Anthropocentric Concepts of Multiplicity, workshop, ICI Berlin, 24–25 March 2022 <https://doi.org/10.25620/e220324

An HLA-I signature favouring KIR-educated Natural Killer cells mediates immune control of HIV in children and contrasts with the HLA-B-restricted CD8+T-cell-mediated immune control in adults

Natural Killer (NK) cells contribute to HIV control in adults, but HLA-B-mediated T-cell activity has a more substantial impact on disease outcome. However, the HLA-B molecules influencing immune control in adults have less impact on paediatric infection. To investigate the contribution NK cells make to immune control, we studied >300 children living with HIV followed over two decades in South Africa. In children, HLA-B alleles associated with adult protection or disease-susceptibility did not have significant effects, whereas Bw4 (p = 0.003) and low HLA-A expression (p = 0.002) alleles were strongly associated with immunological and viral control. In a comparator adult cohort, Bw4 and HLA-A expression contributions to HIV disease outcome were dwarfed by those of protective and disease-susceptible HLA-B molecules. We next investigated the immunophenotype and effector functions of NK cells in a subset of these children using flow cytometry. Slow progression and better plasma viraemic control were also associated with high frequencies of less terminally differentiated NKG2A+NKp46+CD56dim NK cells strongly responsive to cytokine stimulation and linked with the immunogenetic signature identified. Future studies are indicated to determine whether this signature associated with immune control in early life directly facilitates functional cure in children

Inhalative Exposure to Vanadium Pentoxide Causes DNA Damage in Workers: Results of a Multiple End Point Study

BackgroundInhalative exposure to vanadium pentoxide (V(2)O(5)) causes lung cancer in rodents.ObjectiveThe aim of the study was to investigate the impact of V(2)O(5) on DNA stability in workers from a V(2)O(5) factory.MethodsWe determined DNA strand breaks in leukocytes of 52 workers and controls using the alkaline comet assay. We also investigated different parameters of chromosomal instability in lymphocytes of 23 workers and 24 controls using the cytokinesis-block micronucleus (MN) cytome method.ResultsSeven of eight biomarkers were increased in blood cells of the workers, and vanadium plasma concentrations in plasma were 7-fold higher than in the controls (0.31 microg/L). We observed no difference in DNA migration under standard conditions, but we found increased tail lengths due to formation of oxidized purines (7%) and pyrimidines (30%) with lesion-specific enzymes (formamidopyrimidine glycosylase and endonuclease III) in the workers. Bleomycin-induced DNA migration was higher in the exposed group (25%), whereas the repair of bleomycin-induced lesions was reduced. Workers had a 2.5-fold higher MN frequency, and nucleoplasmic bridges (NPBs) and nuclear buds (Nbuds) were increased 7-fold and 3-fold, respectively. Also, apoptosis and necrosis rates were higher, but only the latter parameter reached statistical significance.ConclusionsV(2)O(5) causes oxidation of DNA bases, affects DNA repair, and induces formation of MNs, NPBs, and Nbuds in blood cells, suggesting that the workers are at increased risk for cancer and other diseases that are related to DNA instability.Veronika A. Ehrlich, Armen K. Nersesyan, Kambis Atefie, Christine Hoelzl, Franziska Ferk, Julia Bichler, Eva Valic, Andreas Schaffer, Rolf Schulte‑Hermann, Michael Fenech, Karl‑Heinz Wagner and Siegfried Knasmüllerhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599764

Der Mensch im Experiment:1850-1980

Im Zuge der laboratory revolution wurde der Mensch »Gegenstand« experimenteller Praktiken und wissenschaftlicher Versuchsmethoden. Die Tagung versucht, das Experimentieren am Menschen in seiner für die modernen Lebenswissenschaften konstitutiven Figuration einer historischen und epistemologischen Reflektion zu unterziehen. Dabei soll die starre, oft normative gesetzte Ordnung zwischen »Humanexperiment« einerseits und »Heilversuch« andererseits, zwischen »ethisch verwerflichen« und »moralisch akzeptablen« Menschenversuch aufgebrochen werden. Anhand von Fallbeispielen aus den verschiedensten Disziplinen und geographischen Räumen soll der Status des Menschen als Erkenntnisort im Selbst-, Impf- und Arzneimittelversuch diskutiert werden.Der Mensch im Experiment: 1850-1980, conference, ICI Berlin, 22 May 2008 <https://doi.org/10.25620/e080522

Ten-year survival of ART restorations in permanent posterior teeth

This study evaluated the 10-year clinical performance of high-viscosity glass-ionomer cement placed in posterior permanent teeth by means of the Atraumatic Restorative Treatment (ART) approach. One operator placed 167 single- and 107 multiple-surface restorations in 43 high-risk caries pregnant women (mean decayed teeth = 9.8 ± 5.5). Examinations were performed at 1-, 2-, and 10-year intervals according to ART criteria. In the last evaluation, the US Public Health Service (USPHS) criteria were also used. After 10 years, 129 restorations (47.1%) were evaluated and achieved a cumulative survival rate of 49.0% (SE 7.2%). The 10-year survival of single- and multiple-surface ART restorations assessed using the ART criteria were 65.2% (SE 7.3%) and 30.6% (SE 9.9%), respectively. This difference was significant (jackknife SE of difference; p < 0.05). Using the USPHS criteria, the 10-year survival of single- and multiple-surface ART restorations were 86.5% and 57.6%, respectively. The primary causes of failure were total loss (9.3%) and marginal defects (5.4%). The survival rates observed, especially for the single-surface restorations, confirm the potential of the ART approach for restoring and saving posterior permanent teeth