Neutron scattering studies of helicoidal magnet and 2D magnetic materials

This thesis focuses on the use of complementary neutron scattering techniques to study both statics and dynamics of multiferroic MnSb₂O₆ and crystal and magnetic structures of 2D van der Waals magnetic materials. The first part of this thesis is dedicated to the study of the helicoidal magnet MnSb₂O₆ which crystallizes in the trigonal space group P321. Its structural chirality is coupled to its magnetic ground state under Tₙ ≈ 12 K through symmetric Heisenberg exchanges. One chapter is dedicated to neutron diffraction studies on MnSb₂O₆ for a detailed study of both crystal and magnetic structures. While the magnetic ground state could not be unambiguously determined, between a pure cycloidal or a mixture of cycloidal and helical order, the spin rotation plane can be tilted by the application of low external magnetic field. Subsequently, a mechanism based on the coupled structural and magnetic chiralities is proposed to explain the previously reported ferroelectric switching. The following chapter presents the study of the spin dynamics in MnSb₂O₆. By performing sum rules analysis on inelastic neutron scattering data, the seven exchange constants based on a Heisenberg model are extracted. Testing the stability of the spin excitations validates the cycloidal ground state. The last part of the thesis focuses on the structures of 2D van der Waals magnets. In these materials, the magnetic properties are coupled to the stacking of the twodimensional layers, in particular in Fe₃₋ₓGeTe₂ and Fe₁₊ₓTe, where the magnetism can be tuned by the iron concentration. Single crystal neutron diffraction study on Fe₃₋ₓGeTe₂ is reported as well as spherical neutron polarimetry on Fe₁₊ₓTe. Finally, X-ray powder diffraction results on the crystal structure of honeycomb layered VI₃ are presented

Prevalence of obesity and screening for diabetes among secondary school students

Introduction There is an increasing trend of obesity in children and adolescent globally. The objectives of this study were to identify the prevalence of overweight and obesity among students from secondary schools and to determine the mean random blood sugar (RBS) for the overweight and obese students. Methods This was a cross sectional study. Two secondary schools that were scheduled for visit by the School Health Team, Taiping in July 2016 were included. A standardized data collection sheet was used to collect the data. Overweight and obesity were defined based on WHO 2007 reference for BMI-for-age criteria. Random blood glucose was checked for overweight and obese students. Results A total of 184 school students consented and participated. 128 (69.6%) were female and 90 (48.9%) were Malays. The mean weight and height were 56.21 kg and 1.61 m respectively with BMI of 21.49 kg/m2. Overall, the prevalence of obese and overweight were 12.5% and 10.9% respectively. Among the 4 BMI groups, there were no significant difference found in sex (p=0.849) and races (p=0.536). However, there was significant difference (p=0.042) in mean RBS for obese and overweight students between races. RBS readings among overweight and obese students were within normal range with mean of 5.95 (0.67) mmol/l (range between 4.60 – 7.70 mmol/l). Conclusions The overall prevalence of overweight and obesity were comparable with other studies done in Malaysia. Nevertheless, there was no prevalence of Type II diabetes mellitus among them

Rapid detection of BRCA1/2 recurrent mutations in Chinese breast and ovarian cancer patients with multiplex SNaPshot genotyping panels.

BRCA1/2 mutations are significant risk factors for hereditary breast and ovarian cancer (HBOC), its mutation frequency in HBOC of Chinese ethnicity is around 9%, in which nearly half are recurrent mutations. In Hong Kong and China, genetic testing and counseling are not as common as in the West. To reduce the barrier of testing, a multiplex SNaPshot genotyping panel that targeted 25 Chinese BRCA1/2 mutation hotspots was developed, and its feasibility was evaluated in a local cohort of 441 breast and 155 ovarian cancer patients. For those who tested negative, they were then subjected to full-gene testing with next-generation sequencing (NGS). BRCA mutation prevalence in this cohort was 8.05% and the yield of the recurrent panel was 3.52%, identifying over 40% of the mutation carriers. Moreover, from 79 Chinese breast cancer cases recruited overseas, 2 recurrent mutations and one novel BRCA2 mutation were detected by the panel and NGS respectively. The developed genotyping panel showed to be an easy-to-perform and more affordable testing tool that can provide important contributions to improve the healthcare of Chinese women with cancer as well as family members that harbor high risk mutations for HBOC

The synthesis of substituted phosphabenzenes and arsabenzenes.

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22199/1/0000630.pd

A Preliminary Psychometric Investigation of a Chinese Version of the Engaged Teachers Scale (C-ETS)

This study examines the psychometric properties of a Chinese version of the Engaged Teacher Scale (C-ETS). A translated questionnaire with 16 items was administered to a sample of 341 primary and secondary school teachers in Hong Kong. A series of confirmatory factor analyses were performed to assess the construct, convergent, and discriminant validity of the scale in alternative models. Results provide support for a second-order model with teacher engagement as an overarching construct with four hypothesized dimensions: emotional engagement, cognitive engagement, social engagement (students), and social engagement (colleagues). The C-ETS provides a useful measure for teacher engagement in Chinese societies. Contributions and limitations of the study are discussed

CanadiEM: Accessing a Virtual Community of Practice to Create a Canadian National Medical Education Institution

Background: The rise of free open-access medical education (FOAM) has led to a wide range of online resources in emergency medicine. Canadian physicians have been active contributors to FOAM. Objectives: We aimed to create a virtual community of practice that would serve as a national platform for collaboration, learning, and knowledge dissemination. Methods: CanadiEM was formed in 2016 from the merger of two Canadian websites and a podcast. Using a community-of-practice model, we introduced two training programs to support junior community members in becoming core editorial team members and employed asynchronous Web technologies to facilitate collaboration. We also introduced a coached peer review process and formed strategic alliances that aim to ensure a high quality of publication. Results: CanadiEM has become a portal for readers to access a broad range of FOAM content. The website has published 782 articles. Of these, 71 have undergone a coached peer review process. The website has received over 2.5 million page views from 217 countries, and the associated CRACKCast podcast has been downloaded over 750,000 times. Conclusions: CanadiEM has succeeded in building a national multi-interface dissemination network that fosters collaboration and knowledge sharing in emergency medicine while fostering junior digital scholars. The construction of a community of practice has been facilitated by quality assurance, training programs, and the use of asynchronous Web technologies. Ongoing challenges in sustainability include a volunteer workforce with high turnover

Human Ribosomal Proteins RPeL27, RPeL43 and RPeL41 are Up-regulated in Nasopharyngeal Carcinoma Cell Lines

Apart from their canonical role in ribosome biogenesis, there is increasing evidence of ribosomal protein genes’ involvement in various cancers. A previous study by us revealed significant differential expression of three ribosomal protein genes (RPeL27, RPeL41 and RPeL43) between cell lines derived from tumor and normal nasopharyngeal epithelium. However, the results therein were based on a semi-quantitative assay, thus preliminary in nature. Herein, we provide findings of a deeper analysis of these three genes in the context to nasopharyngeal carcinoma (NPC) tumorigenesis. Their expression patterns were analyzed in a more quantitative manner at transcript level. Their protein expression levels were also investigated. We showed results that are contrary to previous report. Rather than down-regulation, these genes were significantly overexpressed in NPC cell lines compared to normal control at both transcript and protein levels. Nevertheless, their association with NPC has been established. Immunoprecipitation pulldown assays indicate the plausible interaction of either RPeL27 or RPeL43 with POTEE/TUBA1A and ACTB/ACTBL2 complexes. In addition, RPeL43 is shown to bind with MRAS and EIF2S1 proteins in a NPC cell line (HK1). Our findings support RPeL27, RPeL41 and RPeL43 as potential markers of NPC, and provide insights into the interaction targets of RPeL27 and RPeL43 proteins

Predicted interaction of human Ribosomal Protein S15 with Fragile X Mental Retardation Protein

In addition to the central role of ribosome biogenesis, the human ribosomal protein S15 (RPS15) has extra-ribosomal roles that include its association with a congenital disease and a few types of cancer. However, current knowledge of its functions in the context of extra-ribosomal activities remains fragmented. An approach to gain insights into the interaction between RPS15 and possible protein partners is via Bioinformatics strategies. Based on the sequence-to-structure-to-function paradigm, structural data of a protein can be computationally analysed to derive logical interacting partners. This method can include three-dimensional model construction, structural neighbour prediction, and molecular docking analysis. By using this approach, we have constructed RPS15 3D-structural models that have allowed the prediction of 23 structural neighbours. Of these, two that are from human origin were further analysed and only one have logical prospect of binary protein-protein interactions. Further analysis of this structural neighbour revealed 7 candidate docking partners. From these, our molecular docking analysis demonstrated two most logical dock models of interactions between RPS15 with two different domains of the Fragile X Mental Retardation Protein 1 (FMRP1) protein. Hence, we have provided in silico evidence of de novo protein-protein interaction between RPS15 and the Fragile X Mental Retardation Protein 1 (FMRP1)