State of the Art of Laser Hardening and Cladding

In this paper an overview is given about laser surface modification processes, which are developed especially with the aim of hardness improvement for an enhanced fatigue and wear behaviour. The processes can be divided into such with and without filler material and in solid-state and melting processes. Actual work on shock hardening, transformation hardening, remelting, alloying and cladding is reviewed, where the main focus was on scientific work from the 21st century

Course Journals Supporting Social Justice: Developing Equitable Scholarly Communications Through In-class Publishing Projects

How can OJS and OMP be used in classes to engage students in discussions around social justice in scholarly publishing? This presentation will discuss examples of course journals and book projects at Simon Fraser University (SFU) and Kwantlen Polytechnic University (KPU) which attempt to involve students in anti-colonial, anti-racist, and anti-oppressive forms of scholarship. These projects aim to be inclusive in a variety of ways: in terms of accessibility, language, content formats, and sustainability strategies. The presenters discuss the ways that OJS and OMP can be used in the classroom to develop students’ awareness of, and ability to address, social justice concerns in traditional publishing. Finally, they will explore how lessons learned from these case studies can be implemented in other courses

Stability-normalised walking speed: A new approach for human gait perturbation research

© 2019 In gait stability research, neither self-selected walking speeds, nor the same prescribed walking speed for all participants, guarantee equivalent gait stability among participants. Furthermore, these options may differentially affect the response to different gait perturbations, which is problematic when comparing groups with different capacities. We present a method for decreasing inter-individual differences in gait stability by adjusting walking speed to equivalent margins of stability (MoS). Eighteen healthy adults walked on a split-belt treadmill for two-minute bouts at 0.4 m/s up to 1.8 m/s in 0.2 m/s intervals. The stability-normalised walking speed (MoS = 0.05 m) was calculated using the mean MoS at touchdown of the final 10 steps of each speed. Participants then walked for three minutes at this speed and were subsequently exposed to a treadmill belt acceleration perturbation. A further 12 healthy adults were exposed to the same perturbation while walking at 1.3 m/s: the average of the previous group. Large ranges in MoS were observed during the prescribed speeds (6–10 cm across speeds) and walking speed significantly (P < 0.001) affected MoS. The stability-normalised walking speeds resulted in MoS equal or very close to the desired 0.05 m and reduced between-participant variability in MoS. The second group of participants walking at 1.3 m/s had greater inter-individual variation in MoS during both unperturbed and perturbed walking compared to 12 sex, height and leg length-matched participants from the stability-normalised walking speed group. The current method decreases inter-individual differences in gait stability which may benefit gait perturbation and stability research, in particular studies on populations with different locomotor capacities. [Preprint: https://doi.org/10.1101/314757

The effect of age and joint angle on the proportionality of extensor and flexor strength at the knee joint

Functional movements require concerted actions of monoarticular and biarticular agonists and antagonists. Understanding age-related changes of muscle function on performance requires insight in the contributions of different muscles to joint moments. Young and elderly participants performed isometric knee extensions and flexions at combinations of knee and hip joint angles. This approach allowed assessing changes in contribution of monoarticular and biarticular knee joint flexors and extensors. Reduced moments were found for elderly persons (flexors: -43%; extensors: -33%). In the flexor group, this reduction was mainly caused by retardation of the biarticular muscles; in the extensors, by reduced strength of the monoarticular muscles. This age-related reduction of joint moments occurred to be joint angle dependent for the extensors. In the flexor group, the reduction was almost invariant. Due to this difference in joint angle dependence, the proportionality between extensors and flexors varied over joint angles and differed with age. It has been discussed how this is related to changes in performances occurring with age

Remote participation during glycosylation reactions of galactose building blocks: Direct evidence from cryogenic vibrational spectroscopy

The stereoselective formation of 1,2‐cis‐glycosidic bonds is challenging. However, 1,2‐cis‐selectivity can be induced by remote participation of C4 or C6 ester groups. Reactions involving remote participation are believed to proceed via a key ionic intermediate, the glycosyl cation. Although mechanistic pathways were postulated many years ago, the structure of the reaction intermediates remained elusive owing to their short‐lived nature. Herein, we unravel the structure of glycosyl cations involved in remote participation reactions via cryogenic vibrational spectroscopy and first principles theory. Acetyl groups at C4 ensure α‐selective galactosylations by forming a covalent bond to the anomeric carbon in dioxolenium‐type ions. Unexpectedly, also benzyl ether protecting groups can engage in remote participation and promote the stereoselective formation of 1,2‐cis‐glycosidic bonds

10K Ring Electrode Trap - Tandem Mass Spectrometer for Infrared Spectroscopy of Mass Selected Ions

A novel instrumental setup for measuring infrared photodissociation spectra of buffer gas cooled, mass-selected ions is described and tested. It combines a cryogenically cooled, linear radio frequency ion trap with a tandem mass spectrometer, optimally coupling continuous ion sources to pulsed laser experiments. The use of six independently adjustable DC potentials superimposed over the trapping radio frequency field provides control over the ion distribution within, as well as the kinetic energy distribution of the ions extracted from the ion trap. The scheme allows focusing the ions in space and time, such that they can be optimally irradiated by a pulsed, widely tunable infrared photodissociation laser. Ion intensities are monitored with a time-of-flight mass spectrometer mounted orthogonally to the ion trap axis

Global, local and graphical person-fit analysis using person response functions

Person-fit statistics test whether the likelihood of a respondent’s complete vector of item scores on a test is low given the hypothesized item response theory model. This binary information may be insufficient for diagnosing the cause of a misfitting item-score vector. The authors propose a comprehensive methodology for person-fit analysis in the context of nonparametric item response theory. The methodology (a) includes H. Van der Flier’s (1982) global person-fit statistic U3 to make the binary decision about fit or misfit of a person’s item-score vector, (b) uses kernel smoothing (J. O. Ramsay, 1991) to estimate the person-response function for the misfitting item-score vectors, and (c) evaluates unexpected trends in the person-response function using a new local person-fit statistic (W. H. M. Emons, 2003). An empirical data example shows how to use the methodology for practical person-fit analysis