A Simulation of Secondary Electron Trajectories in Solids

A Monte Carlo calculation model is introduced to simulate not only the primary electron behavior but also the secondary electron cascade in a specimen bombarded with an electron beam. Electrons having energy greater than 0.1keV are treated as fast electrons and the single scattering Monte Carlo model is adopted. Electrons having energy smaller than 0.1keV are treated as slow electrons and the electron cascade Monte Carlo model is used. The calculated results for the energy distribution of secondary electrons, and primary electron energy dependence of the total secondary yield and the backscattering yield are in good agreement with experimental results

Monte Carlo Simulation of Secondary Electrons in Solids and its Application for Scanning Electron Microscopy

A new Monte Carlo calculation model is introduced to simulate not only the primary electron behavior but also the secondary electron cascade in a specimen bombarded with an electron beam. Either the primary or the generated electron in a specimen having energy greater than 0.1 keV is defined as a fast electron and the single scattering model is used in the simulation which employs the Mott elastic scattering cross section and the Rao Sahib-Wittry energy loss equation. The electron having energy smaller than 0.1 keV is defined as a slow electron and the cascade model is used which takes into account the classical binary collision with the conduction electrons. The performance of this simulation is verified in comparison with experiments for energy and angular distributions of slow secondary electrons (\u3c50eV). Then, this simulation is applied in a discussion of the quantitative signal variation of the secondary and the backscattered electrons depending on a specimen surface topography. The maximum intensity of the secondary electron signal is obtained where the scanning electron beam reaches around 1nm beside the top edge of a surface step made of Cu with the vertical side wall of 500nm in height

Calculation of a Topographic Contrast in the Scanning Electron Microscope

A direct simulation of electron scattering in solids is developed. Using this simulation, a topographic contrast found in the scanning electron microscope is quantitatively discussed. The surface topography studied here is a rectangular rod pattern and a rectangular groove pattern at an infinite horizontal plane surface of Al. We quantify characteristics of the secondary electron image and of the backscattered electron image at the topography. The intensity profile at the bottom surface of the groove pattern is roughly approximated by an analytical model

Sustainability in practice: a case report of an interdisciplinary online student conference

Sustainable development is interdisciplinary and applicable to all Higher Education subject areas. However, in some curricula its importance is overlooked which presents a barrier to the achievement of the United Nation Sustainable Development Goals (SDGs). To address this, we organised a ‘Sustainability in Practice’ online conference that invited students to discuss ‘Sustainability, what's it got to do with me?’. The conference, embraced a transformational education approach and active learning, included keynote speakers, breakout sessions and research posters. Student feedback highlighted that they found the event valuable and inspirational: the knowledge gained and discussions with academics and peers were particularly helpful. Students also wished for further engagement, emphasising the event's value and impact on their appetite for knowledge. Insights reported will enable other institutions to replicate the conference thereby helping them to develop their own students’ knowledge and facilitate conversations on sustainability, contributing to education for sustainable development and further achieving the SDGs

PathPred: an enzyme-catalyzed metabolic pathway prediction server

The KEGG RPAIR database is a collection of biochemical structure transformation patterns, called RDM patterns, and chemical structure alignments of substrate-product pairs (reactant pairs) in all known enzyme-catalyzed reactions taken from the Enzyme Nomenclature and the KEGG PATHWAY database. Here, we present PathPred (http://www.genome.jp/tools/pathpred/), a web-based server to predict plausible pathways of muti-step reactions starting from a query compound, based on the local RDM pattern match and the global chemical structure alignment against the reactant pair library. In this server, we focus on predicting pathways for microbial biodegradation of environmental compounds and biosynthesis of plant secondary metabolites, which correspond to characteristic RDM patterns in 947 and 1397 reactant pairs, respectively. The server provides transformed compounds and reference transformation patterns in each predicted reaction, and displays all predicted multi-step reaction pathways in a tree-shaped graph

The optical depth of the Universe to ultrahigh energy cosmic ray scattering in the magnetized large scale structure

This paper provides an analytical description of the transport of ultrahigh energy cosmic rays in an inhomogeneously magnetized intergalactic medium. This latter is modeled as a collection of magnetized scattering centers such as radio cocoons, magnetized galactic winds, clusters or magnetized filaments of large scale structure, with negligible magnetic fields in between. Magnetic deflection is no longer a continuous process, it is rather dominated by scattering events. We study the interaction between high energy cosmic rays and the scattering agents. We then compute the optical depth of the Universe to cosmic ray scattering and discuss the phenomological consequences for various source scenarios. For typical parameters of the scattering centers, the optical depth is greater than unity at 5x10^{19}eV, but the total angular deflection is smaller than unity. One important consequence of this scenario is the possibility that the last scattering center encountered by a cosmic ray be mistaken with the source of this cosmic ray. In particular, we suggest that part of the correlation recently reported by the Pierre Auger Observatory may be affected by such delusion: this experiment may be observing in part the last scattering surface of ultrahigh energy cosmic rays rather than their source population. Since the optical depth falls rapidly with increasing energy, one should probe the arrival directions of the highest energy events beyond 10^{20}eV on an event by event basis to circumvent this effect.Comment: version to appear in PRD; substantial improvements: extended introduction, sections added on angular images and on direction dependent effects with sky maps of optical depth, enlarged discussion of Auger results (conclusions unchanged); 27 pages, 9 figure

Positive psychology of Malaysian students: impacts of engagement, motivation, self-compassion and wellbeing on mental health

Malaysia plays a key role in education of the Asia Pacific, expanding its scholarly output rapidly. However, mental health of Malaysian students is challenging, and their help-seeking is low because of stigma. This study explored the relationships between mental health and positive psychological constructs (academic engagement, motivation, self-compassion, and wellbeing), and evaluated the relative contribution of each positive psychological construct to mental health in Malaysian students. An opportunity sample of 153 students completed the measures regarding these constructs. Correlation, regression, and mediation analyses were conducted. Engagement, amotivation, self-compassion, and wellbeing were associated with, and predicted large variance in mental health. Self-compassion was the strongest independent predictor of mental health among all the positive psychological constructs. Findings can imply the strong links between mental health and positive psychology, especially selfcompassion. Moreover, intervention studies to examine the effects of self-compassion training on mental health of Malaysian students appear to be warranted.N/

Initial Stage of Fiber Structure Development in the Continuous Drawing of Poly(ethylene terephthalate)

This is a preprint of an article published in Journal of Polymer Science: Part B: Polymer Physics. 46(19): 2126-2142 (2008).The initial stage of fiber structure development in the continuous neckdrawing of amorphous poly(ethylene terephthalate) fibers was analyzed by in situ wide-angle X-ray diffraction, small-angle X-ray scattering, and fiber temperature measurements. The time error of the measurements (\600 ls) was obtained by synchrotron X-ray source and laser irradiation heating. A highly ordered fibrillar-shaped two-dimensional (smectic-like) structure was found to be formed less than 1 ms after necking. By analyzing its (0010) and (0020) diffractions, the length of the structure 60–70 nm were obtained. A three-dimensionally ordered triclinic crystal began to form with the vanishing of the structure around 1 ms after necking. The amount and size of the crystal were almost saturated within several milliseconds of necking, during which time a mainly exothermic heat of crystallization was also observed.ArticleJournal of Polymer Science: Part B: Polymer Physics. 46(19): 2126-2142 (2008)journal articl