Out-of-plane auxeticity in sintered fibre network mats

Fibre network mats composed of stainless steel exhibit an unusually large out-of-plane auxeticity (i.e. high negative Poisson’s ratio ν) when subjected to in-plane tensile loading. In situ observations in a scanning electron microscope suggest that this is attributable to fibre segment straightening. An investigation was carried out on the effects of fibre volume fraction and network thickness on the auxetic response. Weak inter-layer bonding, high fibre content and low network thickness were found to amplify the auxetic effect.This research was supported by the European Research Council (ERC) (Grant No. 240446). We wish to thank Dr. Kalin Dragnevski at The Laboratory for In situ Microscopy and Analysis (LIMA) in the Department of Engineering Science, Oxford University for the help in setting up the in situ DEBEN experiments.This is the accepted manuscript of a paper published in Scripta Materialia (Neelakantan S, Tan J-C, Markaki AE, Scripta Materialia, 2015, doi:10.1016/j.scriptamat.2015.04.028). The final version is available at http://dx.doi.org/10.1016/j.scriptamat.2015.04.02

Large building facilities towards energy transition

Received: February 10th, 2023 ; Accepted: May 28th, 2023 ; Published: July 6th, 2023 ; Correspondence: [email protected] buildings complexes present significant amounts of energy consumption. Sport centers compose a more special case of large volume buildings, compared to other facilities. This is related not only to the specific requirements of the thermal environment regarding the type of activities taking place as well as the considerable loads enforced by the presence of people. The aim of this paper is to evaluate the energy consumption of a Sports center, through energy audits, extract energy baselines and propose energy-saving interventions and RES utilization. More precisely, a cost-benefit analysis will be carried out to assess the energy production and the relevant contribution of the potential energy interventions. As a result, the priority list of proposed measures will be extracted, with all the data regarding energy gains, capital costs, and cash flows. Particularly, a capital budgeting analysis of each measure will support the final decision of a holistic energy approach at the specific building facilities

Cell structure, stiffness and permeability of freeze-dried collagen scaffolds in dry and hydrated states.

UNLABELLED: Scaffolds for tissue engineering applications should be highly permeable to support mass transfer requirements while providing a 3-D template for the encapsulated biological cells. High porosity and cell interconnectivity result in highly compliant scaffolds. Overstraining occurs easily with such compliant materials and can produce misleading results. In this paper, the cell structure of freeze-dried collagen scaffolds, in both dry and hydrated states, was characterised using X-ray tomography and 2-photon confocal microscopy respectively. Measurements have been made of the scaffold's Young's modulus using conventional mechanical testing and a customised see-saw testing configuration. Specific permeability was measured under constant pressure gradient and compared with predictions. The collagen scaffolds investigated here have a coarse cell size (∼100-150 μm) and extensive connectivity between adjacent cells (∼10-30 μm) in both dry and hydrated states. The Young's modulus is very low, of the order of 10 kPa when dry and 1 kPa when hydrated. There is only a single previous study concerning the specific permeability of (hydrated) collagen scaffolds, despite its importance in nutrient diffusion, waste removal and cell migration. The experimentally measured value reported here (5 × 10(-)(10)m(2)) is in good agreement with predictions based on Computational Fluid Dynamics simulation and broadly consistent with the Carman-Kozeny empirical estimate. It is however about three orders of magnitude higher than the single previously-reported value and this discrepancy is attributed at least partly to the high pressure gradient imposed in the previous study. STATEMENT OF SIGNIFICANCE: The high porosity and interconnectivity of tissue engineering scaffolds result in highly compliant structures (ie large deflections under low applied loads). Characterisation is essential if these scaffolds are to be systematically optimised. Scaffold overstraining during characterisation can lead to misleading results. In this study, the stiffness (in dry and hydrated states) and specific permeability of freeze-dried collagen scaffolds have been measured using techniques customised for low stiffness structures. The scaffold cell structure is investigated using X-ray computed tomography, which has been applied previously to visualise such materials, without extracting any structural parameters or simulating fluid flow. These are carried out in this work. 2-photon confocal microscopy is used for the first time to study the structure in hydrated state.This research was supported by the European Research Council (Grant No. 240446) and the EPSRC (EP/E025862/1). Financial support for MCV and RAB has been provided via the WD Armstrong studentship and the National Institute for Health Research (NIHR), respectively.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.actbio.2016.01.04

Toxicology and cytogenetic analysis of a Drosophila melanogaster mutant resistant to Imidacloprid and DDT

Resistance to all major insecticide classes has developed in numerous and diverse insect field populations. Imidacloprid, the worldwide most used neonicotinoid, has been extensively applied during the last decade for the control of different insect pests. Lately, cases of sporadic resistance also to neonicotinoids, including Imidacloprid, have been reported. Drosophila melanogaster is one of the most popular model organisms in biology and, although not a pest species, a promising model system for insecticide resistance research. In this study, we present a toxicological and karyotypic analysis of a Drosophila mutant (MiT[w-]3R2) resistant to Imidacloprid and cross-resistant to DDT. Karyotype analysis of polytene chromosome of MiT[w-]3R2 flies did not identify any apparent structural change of the polytene chromosome linked with the resistance phenotype

Multivalent binding of PWWP2A to H2A.Z regulates mitosis and neural crest differentiation

Replacement of canonical histones with specialized histone variants promotes altering of chromatin structure and function. The essential histone variant H2A.Z affects various DNA-based processes via poorly understood mechanisms. Here, we determine the comprehensive interactome of H2A.Z and identify PWWP2A as a novel H2A.Z-nucleosome binder. PWWP2A is a functionally uncharacterized, vertebrate-specific protein that binds very tightly to chromatin through a concerted multivalent binding mode. Two internal protein regions mediate H2A.Z-specificity and nucleosome interaction, whereas the PWWP domain exhibits direct DNA binding. Genome-wide mapping reveals that PWWP2A binds selectively to H2A.Z-containing nucleosomes with strong preference for promoters of highly transcribed genes. In human cells, its depletion affects gene expression and impairs proliferation via a mitotic delay. While PWWP2A does not influence H2A.Z occupancy, the C-terminal tail of H2A.Z is one important mediator to recruit PWWP2A to chromatin. Knockdown of PWWP2A in Xenopus results in severe cranial facial defects, arising from neural crest cell differentiation and migration problems. Thus, PWWP2A is a novel H2A.Z-specific multivalent chromatin binder providing a surprising link between H2A.Z, chromosome segregation, and organ development

Translating and validating a Training Needs Assessment tool into Greek

<p>Abstract</p> <p>Background</p> <p>The translation and cultural adaptation of widely accepted, psychometrically tested tools is regarded as an essential component of effective human resource management in the primary care arena. The Training Needs Assessment (TNA) is a widely used, valid instrument, designed to measure professional development needs of health care professionals, especially in primary health care. This study aims to describe the translation, adaptation and validation of the TNA questionnaire into Greek language and discuss possibilities of its use in primary care settings.</p> <p>Methods</p> <p>A modified version of the English self-administered questionnaire consisting of 30 items was used. Internationally recommended methodology, mandating forward translation, backward translation, reconciliation and pretesting steps, was followed. Tool validation included assessing item internal consistency, using the alpha coefficient of Cronbach. Reproducibility (test – retest reliability) was measured by the kappa correlation coefficient. Criterion validity was calculated for selected parts of the questionnaire by correlating respondents' research experience with relevant research item scores. An exploratory factor analysis highlighted how the items group together, using a Varimax (oblique) rotation and subsequent Cronbach's alpha assessment.</p> <p>Results</p> <p>The psychometric properties of the Greek version of the TNA questionnaire for nursing staff employed in primary care were good. Internal consistency of the instrument was very good, Cronbach's alpha was found to be 0.985 (p < 0.001) and Kappa coefficient for reproducibility was found to be 0.928 (p < 0.0001). Significant positive correlations were found between respondents' current performance levels on each of the research items and amount of research involvement, indicating good criterion validity in the areas tested. Factor analysis revealed seven factors with eigenvalues of > 1.0, KMO (Kaiser-Meyer-Olkin) measure of sampling adequacy = 0.680 and Bartlett's test of sphericity, p < 0.001.</p> <p>Conclusion</p> <p>The translated and adapted Greek version is comparable with the original English instrument in terms of validity and reliability and it is suitable to assess professional development needs of nursing staff in Greek primary care settings.</p

Increasing thyroid cancer incidence in Lithuania in 1978–2003

BACKGROUND: The aim of this paper is to analyze changes in thyroid cancer incidence trends in Lithuania during the period 1978–2003 using joinpoint regression models, with special attention to the period 1993–2003. METHODS: The study was based on all cases of thyroid cancer reported to the Lithuanian Cancer Registry between 1978 and 2003. Age group-specific rates and standardized rates were calculated for each gender, using the direct method (world standard population). The joinpoint regression model was used to provide estimated annual percentage change and to detect points in time where significant changes in the trends occur. RESULTS: During the study period the age-standardized incidence rates increased in males from 0.7 to 2.5 cases per 100 000 and in females from 1.5 to 11.4 per 100 000. Annual percentage changes during this period in the age-standardized rates were 4.6% and 7.1% for males and females, respectively. Joinpoint analysis showed two time periods with joinpoint in the year 2000. A change in the trend occurred in which a significant increase changed to a dramatic increase in thyroid cancer incidence rates. Papillary carcinoma and stage I thyroid cancer increases over this period were mainly responsible for the pattern of changes in trend in recent years. CONCLUSION: A moderate increase in thyroid cancer incidence has been observed in Lithuania between the years 1978 and 2000. An accelerated increase in thyroid cancer incidence rates took place in the period 2000–2003. It seems that the increase in thyroid cancer incidence can be attributed mainly to the changes in the management of non palpable thyroid nodules with growing applications of ultrasound-guided fine needle aspiration biopsy in clinical practice