Micro-abrasion resistance of thermochemically treated steels in aqueous solutions: Mechanisms, maps, materials selection

The area of micro-abrasion is an interesting and relatively recent area in tribo-testing methodologies, where small particles of less than 10 μm are employed between interacting surfaces. It is topical for a number of reasons; its direct relation to the mechanisms of the wear process in bio-tribological applications, ease in conducting tests and the good repeatability of the test results. It has widespread applications in conditions used in the space and offshore industries to bio-engineering for artificial joints and implants. There have been many recent studies on the micro-abrasion performance of materials, ranging from work basic metals to nano-structured coatings. However, no significant work is reported on the micro-abrasion resistance of thermochemically treated steels. Hence, this paper looks at the performance of two thermochemically treated steels, Tenifer bath nitride stainless steel (T-SS) and vanadized carbon steel (V-CS) in such conditions with reference to the stainless steel (SS) by varying the applied load and sliding distance. The results indicated that T-SS demonstrates exceptionally poor resistance to micro-abrasion. It was observed that the heat treatment process and properties of the hardened layer (hardness and thickness) are extremely important in determining the micro-abrasion resistance of such steels. Finally, the results were used to develop micro-abrasion mechanism and wastage maps, which can be used to optimize the surface treated materials for micro-abrasion resistance

Inquiry based learning: why buying a car with a tree included? Enhancing science and mathematic learning

International reports reveal a deficient situation in relation to science and mathematics learning, which can be considered as an obstacle for the education of literate and informed citizens and the qualification and the preparation of future scientists and engineers. This situation may be partly attributed to the way science and mathematics are taught at school. Research on effective teaching approaches shows that inquiry based learning (IBL) improves students’ engagement and motivation for science and mathematics learning and promotes the development of process skills, critical thinking and conceptual understanding of some science and mathematics topics. The present work describes the design and implementation of an instructional approach for enhancing science and mathematics learning through IBL. The instructional approach is based on the design of an interdisciplinary task which starts by challenging students through the analysis of an advertisement. The initial scenario engages students in an investigation process to look for evidence and understanding while acquiring meaningful learning of key science topics and mathematical tools. The task also takes advantage of current technological resources to facilitate and support the overall inquiry process. (Orig.

A semi-discrete line-free method of monopoles for dislocation dynamics

We develop a semi-discrete particle method for Volterra dislocation currents in which the particles, or monopoles, represent an element of line and carry a Burgers vector. The monopoles move according to mobility kinetics driven by elastic and applied forces. The divergence constraint of Volterra dislocation currents is enforced weakly through mesh-free interpolation and an explicit linear connectivity, or ‘sequence’, between the monopoles need not be defined. In this sense, the method is ‘line-free’, i. e., it sidesteps the need to track dislocation lines. This attribute offers significant computational advantages in terms of simplicity, robustness and efficiency, especially as regards the tracking of complex dislocation patterns, including topological transitions. We illustrate the range and scope of the method, by means of an example of application concerned with the plastic hardening of nano-sized grains under monotonic loading

Profil Ibu Rumah Tangga yang Bekerja sebagai Penyapu Jalan di Kota Pekanbaru

This research was conducted to find out how the recruitment process and the factors that influence the Housewife chose to work as a street sweeper in Pekanbaru. Where in this Pekanbaru City street sweeper more women than men. To find out how the recruitment process and factors such mempengaruhui Housewife chose to work as a street sweeper in Pekanbaru, the authors conducted data collection by using the technique of direct interview with the respondents using a list of questions prepared in advance, and also that researchers obsevarsi directly observing the behavior of the respondent. Using purposive sampling technique that researchers have determined the subject of research with the assumption or opinion of himself as a subject research. Results of research conducted that the recruitment process Housewife be a street sweeper in Pekanbaru is relatively easy because the terms are defined not difficult to include are: photocopy KK (family card), a copy of ID card (Identity Card), and a cover letter. Street sweeper is supervised by a foreman at each working area, street sweeper was divided into two, namely: sweeper median (1), sweeper sand (2). The median is the sweeper sweeping trash system with the middle area of the road that separates the space between the right and left of the road, while the sweeper sand or so-called sweeper edge is swept trash system aupun sand with right or left area roads. The husbands income is not sufficient is one of the factors that affect their work as a street sweeper. Allocation of their income to meet their childs school fees in addition to working as a street sweeper they can meet the needs of themselves without having to like buying clothes, veil, powder, and else.Keywords : Motivation , Status and Role , Women and Wor

Coupled thermoelastic simulation of nanovoid cavitation by dislocation emission at finite temperature

In this work we study the early onset of void growth by dislocation emission at finite temperature in single crystal of copper under uniaxial loading conditions using the HotQC method. The results provide a detailed characterization of the cavitation mechanism, including the geometry of the emitted dislocations, the dislocation reaction paths and attendant macroscopic quantities of interest such as the cavitation pressure. In addition, this work shows that as prismatic dislocation loops grow and move away from the void, the material surrounded by these loops is pushed away from the void surface, giving rise to a flux of material together with a heat flux through the crystal

Relative efficiency and validity properties of a visual analogue vs a categorical scaled version of the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index: Spanish versions

AbstractObjective: To compare the performance of visual analogue (VAS) vs categorical (CT) scaled versions of the three subscales (pain, stiffness and difficulty) of the WOMAC Index in patients with knee osteoarthritis.Material and methods: Patients with knee OA (at least grade II of Kellgren & Lawrence classification) were treated for a 6-weeks period with an NSAID. The following measures were applied at baseline and after treatment: VAS and CT WOMAC scales, Lequesne Index, pain on VAS, and global assessment by patient and observer. Construct Validity was determined by correlation of each of the subscale scores with the other outcomes both at baseline and after treatment (Pearson’s test); responsiveness comparing baseline vs final status by Wilcoxon’s test; reliability by analysis of the internal consistency using Cronbach’s alpha at baseline and after the treatment period; and test–retest reliability by Kendall’s Tau-c statistics. Finally, correlation and analysis of the relative efficiency (RE) between the subscales of both formats were tested.Results: Seventy-three (8 men and 65 women) patients with a mean disease duration from first diagnosis of 69 months (3 to 254) completed the study. The following were the observed values for the instruments’ psychometric properties: (1) construct validity: correlations ranged from 0.30 to 0.84 for VAS and 0.27 to 0.77 for CT subscales; (2) responsiveness: achieved P values for the pain, stiffness and difficulty scales were P<0.0001, P=0.002 and P<0.0001 in VAS and P=0.003, P<0.0001 and P=0.001 in CT format respectively; (3) internal consistency: the obtained Cronbach’s alpha coefficients ranged from 0.71 to 0.97 for the VAS and 0.64 to 0.95 for the CT subscales; (4) test–retest reliability: correlation coefficients ranged from 0.36 to 0.76 for VAS and 0.34 to 0.52 for CT subscales; and (5) the relative efficiency of the subscales in VAS vs CT format were 2.20, 0.91 and 1.91 for pain, stiffness and difficulty respectively. Significant correlations between subscales in both formats ranging from 0.72 to 0.86 were observed.Conclusion: We have shown that both the VAS version of WOMAC have adequate evaluative and discriminative properties. We found the pain and physical function scales in VAS format and the stiffness scale in CT format to have a slightly better performance in this sample