Input error sensitivity of hardness and elastic modulus evaluated from indentation load-displacement records by Oliver and Pharr method

Due to its straightforwardness and the ease of implementation the Oliver-Pharr method [1] has been used in the analysis of load-displacement records for more than a decade now. This paper provides analytical expressions relating the errors in the hardness and elastic modulus obtained by this method to systematic calibration errors of measured depth, force and frame compliance for spherical and sharp indentation. While in systems with zero frame compliance the sensitivity ratios for depth and force measurement were found to be constant, in systems with a finite frame compliance the error sensitivity changes with the absolute values of applied force and measured depth. The analytical predictions are compared with the true variation in derived materials parameters and the ranges of validity of the expressions are established. The error sensitivity with respect to different input variables and its implications for the actual measurement are discussed.     

Bloggers’ Responses to the Snowden Affair: Combining Automated and Manual Methods in the Analysis of News Blogging

The Snowden affair gave rise to a huge public debate about not only the legitimacy of the secret surveillance programs he revealed but also about Snowden himself and about the accuracy of the information he leaked. In this paper we present an analysis of how the affair was discussed in the English language blogosphere, based on a corpus of 15,000 blog posts written about Snowden and published from June 2013 to June 2014, as a sub-corpus of a larger corpus of 100,000 blog posts on the topic of surveillance, written during the period 2006–2014. Automated tools are used to identify the topics that characterize the blogging about surveillance and the posts about the Snowden affair. Through an in-depth analysis of the blog posts that commented on Snowden’s revelations of the PRISM program for surveillance of social media users, we chart how bloggers responded to Snowden and his role in this disclosure, whether they found the information credible, and the extent to which they expressed criticism of the surveillance practices. The analysis is used as a basis for discussing the role of blogs in the civic engagement during the first phase of the Snowden affair.     

Application acoustic emission method during concrete frost resistance

Frost resistance is one of the most frequent characteristics of concrete. It is a very complex subject and the test methods themselves are still in development and the international consensus on methodology is still sought, too. The determination concrete frost resistance takes several weeks, months or even more than a year. However micro-structural changes as micro-cracks have not been described sufficiently. Acoustic Emission Method as unusual Non-Destructive Methods can help to monitor structural changes during common frost resistance measuring. Note the Acoustic Emission Method detects only active “defects” into monitored structure. Thus when e.g. crack grows some acoustic waves spread from crack place, i. e. from acoustic emission source. The method does not detect geometric discontinuities and “passive” defects. Selected Non-Destructive Methods as Ultrasound, Non-Linear Ultrasonic Spectroscopy, Impact Echo etc. are used to confirm micro-structural changes. The article describes the first experiment with its imperfections, difficulties and possibilities.     

Global‐view coefficients: a data management solution for parallel quantum Monte Carlo applications

Quantum Monte Carlo (QMC) applications perform simulation with respect to an initial state of the quantum mechanical system, which is often captured by using a cubic B‐spline basis. This representation is stored as a read‐only table of coefficients and accesses to the table are generated at random as part of the Monte Carlo simulation. Current QMC applications, such as QWalk and QMCPACK, replicate this table at every process or node, which limits scalability because increasing the number of processors does not enable larger systems to be run. We present a partitioned global address space approach to transparently managing this data using Global Arrays in a manner that allows the memory of multiple nodes to be aggregated. We develop an automated data management system that significantly reduces communication overheads, enabling new capabilities for QMC codes. Experimental results with QWalk and QMCPACK demonstrate the effectiveness of the data management system. Copyright © 2016 John Wiley & Sons, Ltd.     

Deposition and properties of high-velocity-oxygen-fuel and plasma-sprayed Mo-Mo2C composite coatings

Molybdenum thermal-spray coatings, dispersion strengthened by molybdenum oxides and molybdenum carbides, play an important role in industrial tribological applications. Traditionally, they have been prepared by plasma and wire flame spraying. High porosity and lower cohesion strength limit their application in situations where both galling and abrasion wear is involved. In this study, high-velocity-oxygen-fuel (HVOF) deposition of molybdenum and molybdenum carbide coatings was attempted. Deposition was achieved for all powders used. Composition, microstructure, mechanical, and wear properties of the HVOF synthesized coatings were evaluated and compared with plasma-sprayed counterparts. The HVOF coatings possessed a very good abrasion resistance, whereas plasma deposits performed better in dry sliding tests. Measurements showed a close relationship between the coating surface hardness and its abrasion resistance. Results also suggested correlation between molybdenum carbide distribution in the molybdenum matrix and the sliding friction response of Mo-Mo₂C coatings.     

Isolation,Culture and Comprehensive Characterization of Biological Properties of Human Urine-Derived Stem Cells

Mesenchymal stem cells (MSCs) represent an attractive source within the field of tissue engineering. However, their harvesting often requires invasive medical procedures. Urine-derived stem cells (UDSCs) display similar properties to MSCs, and their obtention and further processing is non-invasive for the donors as well as low cost. Here, we offer a comprehensive analysis of their biological properties. The goal of this study was to analyze their morphology, stemness, differentiation potential and cytokine profile. We have successfully isolated UDSCs from 25 urine samples. First colonies emerged up to 9 days after the initial seeding. Cell doubling time was 45 ± 0.24 SD, and when seeded at the density of 100 cells/cm², they formed 42 ± 6.5 SD colonies within 10 days. Morphological analyzes revealed that two different types of the cell populations have been present. The first type had a rice-grain shape and the second one was characterized by a polyhedral shape. In several cell cultures, dome-shaped cells were observed as well. All examined UDSCs expressed typical MSC-like surface markers, CD73, CD90 and CD105. Moreover, conditioned media from UDSCs were harvested, and cytokine profile has been evaluated showing a significantly higher secretory rate of IL-8, IL-6 and chemokines MCP-1 and GM-CSF. We have also successfully induced human UDSCs into chondrogenic, osteogenic and myogenic cell lineages. Our findings indicate that UDSCs might have immense potential in the regeneration of the damaged tissues.     

The Role of Tenascin C in Cardiac Reverse Remodeling Following Banding–Debanding of the Ascending Aorta

Background: Tenascin-C (TN-C) plays a maladaptive role in left ventricular (LV) hypertrophy following pressure overload. However, the role of TN-C in LV regression following mechanical unloading is unknown. Methods: LV hypertrophy was induced by transverse aortic constriction for 10 weeks followed by debanding for 2 weeks in wild type (Wt) and TN-C knockout (TN-C KO) mice. Cardiac function was assessed by serial magnetic resonance imaging. The expression of fibrotic markers and drivers (angiotensin-converting enzyme-1, ACE-1) was determined in LV tissue as well as human cardiac fibroblasts (HCFs) after TN-C treatment. Results: Chronic pressure overload resulted in a significant decline in cardiac function associated with LV dilation as well as upregulation of TN-C, collagen 1 (Col 1), and ACE-1 in Wt as compared to TN-C KO mice. Reverse remodeling in Wt mice partially improved cardiac function and fibrotic marker expression; however, TN-C protein expression remained unchanged. In HCF, TN-C strongly induced the upregulation of ACE 1 and Col 1. Conclusions: Pressure overload, when lasting long enough to induce HF, has less potential for reverse remodeling in mice. This may be due to significant upregulation of TN-C expression, which stimulates ACE 1, Col 1, and alpha-smooth muscle actin (α-SMA) upregulation in fibroblasts. Consequently, addressing TN-C in LV hypertrophy might open a new window for future therapeutics.     

Mixture Condensation of Ethanol/Water and Ethanol/Siloxane in a Vertical Double Pipe

Eco-friendly mixtures may substitute pure working fluids in thermodynamic cycle processes, yet the existing calculation approaches of mixture condensation are complex due to iterative procedures and multiple input data. To simplify condenser design, this project aims for a new calculation method of mixtures. On this behalf, experimental data for the condensation of ethanol/water and ethanol/octamethyltrisiloxane is provided within a wide composition range to identify the most influential parameters. Finally, a practical prediction method for heat transfer coefficients of mixtures is suggested.     

Quantum monte carlo methods for electronic structure of nanosystems

We provide a brief review of recent applications of quantum Monte Carlo (QMC) methods to the electronic structure of nanosystems. We report on calculations of carbon rings with second-order Jahn-Teller effect, energy ordering of silicon clusters, dissociation enthalpies of protonated hydrogen clusters, and other interesting challenges. We point out the QMC accuracy and outline a few ideas that characterize the current position of QMC among the electronic structure methods and its future development.