Stress intensity factor calculation for a modified round bend bar by 3-D finite element analysis

Stress intensity factors were calculated for a modified round bend bar (MRBB) using 3-D finite element analysis. The results were compared with published solutions for a rectangular and round bend bars. The stress intensity values for the MRBB are between those for the two other geometries as expected. The stress intensity solutions were non-dimensionalized utilizing limit solution for short and long cracks.     

Two are Better than One: Combining ZnO and MgF2 Nanoparticles Reduces Streptococcus pneumoniae and Staphylococcus aureus Biofilm Formation on Cochlear Implants

Streptococcus pneumoniae (S. pneumoniae) and Staphylococcus aureus (S.aureus) are considered the most common colonizers of cochlear implants (CI), which have prompted the search for new ways to inhibit their growth and biofilm development. In the current study, CI‐based platforms are prepared and sonochemically coated with ZnO or MgF₂ nanoparticles (NPs), two agents previously shown to possess antibacterial properties. Additionally, a method is developed for coating both ZnO and MgF₂ on the same platform to achieve synergistic activity against both pathogens. Each surface is characterized, and the optimal conditions for the NP homogenous distribution on the surface are determined. The ZnO‐MgF₂ surface significantly reduces the S. pneumoniae and S. aureus biofilm compared with the surfaces coated with either ZnO or MgF₂, even though it contains smaller amounts of each NP type. Importantly, leaching assays show that the NPs remain anchored to the surface for at least 7 d. Finally, biocompatibility studies demonstrate that coating with low concentrations of ZnO‐MgF₂ results in no toxicity toward primary human fibroblasts from the auditory canal. Taken together, these findings underscore the potential of using NP combinations such as the one presented here to efficiently inhibit bacterial colonization and growth on medical devices such as CIs.     

Performance improvement analysis of boiling water reactors by incorporation of hydride fuel

The feasibility of improving the neutronic characteristics of boiling water reactors (BWR) by using U–Zr hydride fuel is studied. Several modified BWR fuel assembly designs are considered. These include designs in which hydride fuel rods replace water rods only, replace water rods and a fraction of the oxide fuel rods, replace oxide fuel in the upper half of all the fuel rods, and replace all the oxide fuel in the assembly. It is found that replacement of at least half of the oxide fuel rods in the fuel assembly by U–ZrH_1.6 fuel might simultaneously improve the performance of BWR in three ways: (a) Increasing the energy extracted per fuel assembly and the cycle length by up to 10%. (b) Reducing the uranium ore and SWU requirements by approximately 10%. (c) Reducing the negative void coefficient of reactivity by, at least, 50%. It is also found that replacement of all the oxide fuel by hydride fuel opens interesting new options for the design of BWR fuel assemblies. The net result might be simplified assembly designs that can generate significantly more energy while featuring small negative void coefficient of reactivity. U–ThH₂ fuel appears to be even more promising than U–ZrH_1.6. For the potential benefits from hydride fuel to be realized, a clad material that is not permeable to hydrogen and is not as neutron absorbing as stainless steel needs to be developed.     

Disassembly analysis through time estimation and other metrics

This paper examines the problem of assessing product ease of disassembly for recycling in light of the broader issue of manufacturability evaluation. The disassembly time estimation method outlined here is shown to provide one of several needed metrics for use during product design. Moreover, the ability to estimate process time provides the foundation upon which other metrics can be developed. The evaluation based on disassembly time is demonstrated on an electric drill example, and the difficulties associated with generating other disassemblability metrics are discussed.     

A programming approach to mathematics

This article presents an attempt to employ a programming approach to mathematical formalization. Six self-instructional units (120 instructional hours) have been developed for the Open University in Israel. This material was tried on three different types of populations: (a) bright high school students (11th–12th grade, A-level mathematics), (b) mathematics teachers with a programming background, and (c) university students studying mathematics, natural sciences and engineering. The results indicated that the programming approach is complementary to high school and university mathematics. The opportunity to explore, the algorithmic approach to mathematical operations and the visualization of mathematical objects and processes facilitates mathematical understanding and insights. It was most beneficial to the majority of the students who perform on a moderate level of abstraction. The course was less advantageous to those who have a very abstract way of perceiving mathematics or to those who are interested in mathematics only on a technical level. However, the vast majority of students gained new ways of understanding mathematical topics such as functions, curves, probability, game theory, recursive functions, envelopes, tiling, curve fitting, etc. They gained, as well, new strategies of using microcomputers to solve and further explore many mathematical problems which they could not solve before.     

Approaches of truck drivers and non-truck drivers toward reckless on-road behavior

The purpose of the study was to compare the reported approaches of truck drivers to those of non-truck drivers toward reckless on-road behaviors. One hundred and sixty-seven adult males, including 70 non-truck drivers, completed the questionnaires voluntarily. The truck drivers were employees of a concrete manufacturing company working at various company plants throughout Israel. Seventy were professional mixer truckers and 27 were tip-truckers. The participants completed the Reckless Driving Self-Report Scale based on Taubman Ben-Ari et al. [Taubman Ben-Ari, O., Florian, V., Mikulincer, M., 1999. The impact of mortality salience on reckless driving: a test of terror management mechanisms. Journal of Personality and Social Psychology 76, 35-45], adapted for truck drivers for this study. It was expected that non-professional, as compared to professional (truck) drivers, would be more permissive regarding reckless driving, since driving risks are less prominent in their daily driving experience. An ANOVA performed on mean reckless-driving scores yielded significant results. The post hoc Schéffe test indicated significantly higher reckless-driving scores for automobile drivers as compared to both mixer-truck driver scores and tip-truck driver scores. In addition, the reckless-driving scores for mixer-truck drivers were significantly higher than the tip-truck driver scores. We discuss various explanations for the findings and consider possible implications for training strategies in organizations as well as for media campaigns focused on mutual safe road use of truck drivers and private vehicle drivers.     

Solvent-Induced Self-Assembly of Highly Hydrophobic Tetra- and Pentaphenylalanine Peptides

Diphenylalanine peptide (FF) self-assembles into ordered structures of notable physical properties. Moreover, the ability of the phenylalanine amino acid or triphenylalanine to assemble into ordered nanostructures had been demonstrated. Herein, we explored the association potential of larger phenylalanine peptides, tetraphenylalanine, and pentaphenylalanine. A major challenge in studying the assembly of these peptides is their lack of solubility in different solvents. Yet, the remarkable capacity of acetic acid to solubilize FF was recently shown. Inspired by this, we examined whether this solvent could also be employed to dissolve these insoluble peptides. By utilizing the solvent-switch methodology, we revealed the self-assembly of tetraphenylalanine and pentaphenylalanine. The peptides were assembled into ordered autofluorescent elongated structures, which were further characterized by electron microscopy and spectroscopy analysis and could be utilized in future technological applications.