Influence of clamp-widening on the quality factor of nanomechanical silicon nitride resonators

Nanomechanical resonators based on strained silicon nitride (Si$_3$N$_4$) have received a large amount of attention in fields such as sensing and quantum optomechanics due to their exceptionally high quality factors ($Q$s). Room-temperature $Q$s approaching 1 billion are now in reach by means of phononic crystals (soft-clamping) and strain engineering. Despite great progress in enhancing $Q$s, difficulties in fabrication of soft-clamped samples limits their implementation into actual devices. An alternative means of achieving ultra-high $Q$s was shown using trampoline resonators with engineered clamps, which serves to localize the stress to the center of the resonator, while minimizing stress at the clamping. The effectiveness of this approach has since come into question from recent studies employing string resonators with clamp-tapering. Here, we investigate this idea using nanomechanical string resonators with engineered clampings similar to those presented for trampolines. Importantly, the effect of orienting the strings diagonally or perpendicularly with respect to the silicon frame is investigated. It is found that increasing the clamp width for diagonal strings slightly increases the $Q$s of the fundamental out-of-plane mode at small radii, while perpendicular strings only deteriorate with increasing clamp width. Measured $Q$s agree well with finite element method simulations even for higher-order resonances. The small increase cannot account for previously reported $Q$s of trampoline resonators. Instead, we propose the effect to be intrinsic and related to surface and radiation losses.Comment: 7 pages, 4 figure

TDP1/TOP1 ratio as a promising indicator for the response of small cell lung cancer to topotecan

BACKGROUND AND OBJECTIVE Small cell lung cancer (SCLC) is one of the most challenging tumors to treat due to high proliferation rate, early metastatic dissemination and rapid development of chemotherapy resistance. The current treatment protocols involve the use of topoisomerase 1 (TOP1) poisons such as irinotecan and topotecan in combination with platinum-based compounds. TOP1 poisons kill cancer cells by trapping TOP1 on DNA, generating lethal DNA double-strand breaks. A potential mechanism employed by cancer cells to resist killing by TOP1 poisons is to overexpress enzymes involved in the repair of TOP1-DNA breaks. Tyrosyl DNA phosphodiesterase 1 (TDP1) is a key player in this process and despite its importance, no data is currently available to correlate TDP1 protein and mRNA levels with catalytic activity in SCLC. In addition, it is not known if TDP1 and TOP1 protein levels correlate with the cellular response of SCLC to TOP1 based therapies. METHODS AND RESULTS We report a remarkable variation in TDP1 and TOP1 protein levels in a panel of SCLC cell lines. TDP1 protein level correlates well with TDP1 mRNA and TDP1 catalytic activity, as measured by two newly developed independent activity assays, suggesting the potential utility of immunohistochemistry in assessing TDP1 levels in SCLC tissues. We further demonstrate that whilst TDP1 protein level alone does not correlate with topotecan sensitivity, TDP1/TOP1 ratio correlates well with sensitivity in 8 out of 10 cell lines examined. CONCLUSION This study provides the first cellular analyses of TDP1 and TOP1 in SCLC and suggests the potential utility of TDP1/TOP1 ratio to assess the response of SCLC to topotecan. The establishment and validation of an easy-to-use TDP1 enzymatic assay in cell extracts could be exploited as a diagnostic tool in the clinic. These findings may help in stratifying patients that are likely to benefit from TOP1 poisons and TDP1 inhibitors currently under development

Care for Those Who Care for the Planet: Grant-making for staff development

People are the wealth of an organisation. To thrive, employees need well-being and appreciation. While salary is a crucial part of valorisation, many other aspects of valorisation at work are not linked with financial compensation. Working for a cause that makes sense, Capacity Building, and support in Leadership, Organisational Development and/or Networking are non-financial compensation ways that should be promoted to allow NGO workers to thrive at work and ultimately to have more impact.But all these tools are investments and should be funded. At MAVA, we believe our engagement includes taking care of the partner organisations we work with, by providing them the means to take care of their staff.'Care those who care the planet: Grant making for staff development' is a publication by MAVA. In this paper, we explore the ways of supporting staff development as part of grant-making and how full staff costs of NGOs could be included in budgets and funding. As employees of a donor, we encourage funders to embrace the importance of staff valorisation and caring for those who care for the planet

Finishing of SLS-Parts for Rapid Manufacturing (RM) - A Comprehensive Approach

Plastic parts are often coated to fulfill the desired functional requirements during product life. This may be for decorative purposes only, but also for functions such as improved tribology, wear and humidity resistance, UV- and light stability, hygienic and biofilm resistance. Moving SLS towards Rapid Manufacturing (RM) and making those parts competitive with parts produced by other techniques (e.g. injection molding) implies the adoption of a new quality of part finishing and coating strategy for SLS. This paper provides a survey of current finishing methods used for RM-SLS parts in our institute and highlights the manually-driven process steps. The need for, and first trials with, a more automated finishing process (e.g. vibratory grinding) are discussed, as is the need for innovative supporting software tools.Mechanical Engineerin

Spin nematics in the bilinear-biquadratic S=1 spin chain

We report the existence of an extended critical, nondimerized region in the phase diagram of the bilinear-biquadratic spin-one chain. The dominant power law correlations are ferroquadrupolar, i.e. spin nematic in character. Another known critical region is also characterized by dominant quadrupolar correlations, although with a different wave vector. Our results show that spin nematic correlations play an important role in quantum magnets with spin S >= 1 in regions between antiferromagnetic and ferromagnetic phases.Comment: 4 pages, 7 figure

Host-Plant Selectivity of Rhizobacteria in a Crop/Weed Model System

Belowground microorganisms are known to influence plants' performance by altering the soil environment. Plant pathogens such as cyanide-producing strains of the rhizobacterium Pseudomonas may show strong host-plant selectivity. We analyzed interactions between different host plants and Pseudomonas strains and tested if these can be linked to the cyanide sensitivity of host plants, the cyanide production of bacterial strains or the plant identity from which strains had been isolated. Eight strains (four cyanide producing) were isolated from roots of four weed species and then re-inoculated on the four weed and two additional crop species. Bacterial strain composition varied strongly among the four weed species. Although all six plant species showed different reductions in root growth when cyanide was artificially applied to seedlings, they were generally not negatively affected by inoculation with cyanide-producing bacterial strains. We found a highly significant plant species x bacterial strain interaction. Partitioning this interaction into contrasts showed that it was entirely due to a strongly negative effect of a bacterial strain (Pseudomonas kilonensis/brassicacearum, isolated from Galium mollugo) on Echinochloa crus-galli. This exotic weed may not have become adapted to the bacterial strain isolated from a native weed. Our findings suggest that host-specific rhizobacteria hold some promise as biological weed-control agents

Presentación del Plan de Digitalización para las bibliotecas del CSIC

Sección: La RedA finales del mes de abril ha visto la luz el Plan de Digitalización para la Red de Bibliotecas del CSIC. Este plan tiene como objetivo crear una política unitaria que guíe a las bibliotecas en la aplicación de criterios comunes y estándares de uso para el adecuado desarrollo de los proyectos de digitalización. Se busca con ello sentar las bases para la creación y desarrollo de una colección digital propia del CSIC de proyección internacional y con visos de perdurabilidad. Aunque el plan está concebido pensando principalmente en los fondos patrimoniales y libres de derechos de autor, las pautas técnicas y los criterios de selección ahí expuestos son una buena guía para el desarrollo de cualquier proyecto de digitalización.N