Olefin Metathesis by Supported Metal Oxide Catalysts

Olefin metathesis is considered to be a green route to production of olefins due to its high selectivity towards desired products. Due to their ease of preparation and catalyst lifetimes, heterogeneous supported metal oxide catalysts such as ReOx, MoOx and WOx are used at large scale industrial applications. Despite decades of catalysis research, the exact nature of catalytic active sites, reaction intermediates and kinetics are not well understood because of lack of modern characterization techniques in the past and absence of detailed knowledge at the molecular level. Extensive in situ and operando spectroscopy (Raman, UV vis, XAS and IR) experiments, theoretical DFT calculations, steady-state kinetics and temperature programmed surface reaction (TPSR) studies were undertaken for the first time to obtain unprecedented insights about the catalytic active sites (their anchoring sites, coordination and oxidation states), reaction intermediates, olefin adsorption/desorption/reaction and kinetics to unravel the fundamental molecular structure-reactivity relationships. The supported ReOx/Al2O3 system is the most reactive among the heterogeneous supported metal oxide catalysts. The long standing debates surround the nature of ReOx species, number of reactive intermediates and kinetics of this catalytic system. In situ 18O-16O Raman experiments along with in situ XAS and theoretical DFT calculations of the initial catalyst show that rhenia exists on the Al2O3 support as two distinct isolated surface ReO4 species with dioxo coordination. The two structures are related to their anchoring at different surface hydroxyl sites on the alumina support. The surface ReO4-I species on basic alumina sites were found to be stable and difficult to activate with propylene while the surface ReO4-II species on acidic alumina sites were found to be easily activated with propylene. This information allowed for the first time the use of acidic promoters to block formation of the inactive surface ReO4-I species and design catalysts with only active surface ReO4-II species.During activation with propylene, in situ UV-vis and XAS spectroscopy revealed that the surface ReO4-II species become partially reduced, mostly to Re+5 species, by forming the oxygenated CH3CHO and HCHO products (pseudo-Wittig mechanism). Subsequent reaction of the partially reduced Re+5 species with propylene oxidizes rhenia back to reactive Re+7-carbenes (Re=CH2, Re=CHCH3, etc.). The surface Re+7-carbenes are reactive at room temperature and in equilibrium with the gas phase olefins. Consequently, removal of the gas phase olefins significantly diminishes the concentration of reactive surface Re+7-carbenes by about an order of magnitude. This accounts for the low number of reactive intermediates reported in earlier studies that evacuated the catalysts prior to titrating the reactive intermediates.Two types of surface intermediates were found to be present: weakly adsorbed that reacts at room temperature and strongly adsorbed π-complexes that reacts at high temperatures (\u3e100oC). The weakly adsorbed Re-carbenes are dynamic and in equilibrium with the gas phase. The strongly adsorbed π-complexes are not dependent on the gas phase composition and only react with olefins at elevated temperatures. TPSR studies showed that the weakly bound Re-carbenes follows a unimolecular reaction mechanism while the strongly bound π-complexes follow a bimolecular reaction mechanism. The olefin metathesis steady-state kinetics is affected by these intermediates: first-order in propylene partial pressure at low temperatures (\u3c70oC) and second-order in propylene partial pressure at high temperatures (\u3e140oC). C3H6/C3D6 TPSR studies also demonstrated that the rate-determining-step does not involve C-H bond breaking and all olefins share the same rate desorption rate.These new unprecedented insights are able to resolve the confusing claims that existed for decades in literature

Revisiting a Structural Analysis of Folktales: a Means to an End?

Folktales have been regarded as the simplest form of narrative and tales from various cultures have been analyzed in terms of their structure. The structural analysis of ta[1]les can be claimed to begin with Propp’s (1958/1968) Morphology of the Folktale. Following Propp’s ground-breaking morphological classification of Russian tales, studies of structural typology of folktales from different cultures have given rise to story-grammars and led to the heyday of narratology. However, with the growing interest in narrative as a social and psychological phenomenon, structural analyses of stories have come under attack. It is contended that although the explorations of story structures have resulted in interesting descriptions of different models, what is lacking is an explanation of how formal patterns are related to the story’s content. Therefore, more recent works in narratological research have called for a narrative analysis to go beyond structures. This article revisits a structure analysis of folktales. Using a Myanmar (Burmese) folktale as a tutor text, it advocates an investigation of the relationship between form, function and field of a tale, and suggests a structural analysis as a means to gain insights into the cultural determination of the narrative motif and the social purpose of storytelling.  &nbsp

PROMOTING LANGUAGE LEARNERS’ CROSS-CULTURAL AWARENESS THROUGH COMPARATIVE ANALYSES OF ASIAN FOLKTALES

With the global spread, the English language has become a lingua franca and a component of basic education in many Asian countries, making Asia one of the regions in the world with the largest number of English speakers. However, due to the rich cultural diversities of Asian societies, using English as a lingua franca in Asia implies that speakers need to develop not only communicative competence but intercultural communicative competence, so as to ensure successful communication among people from different Asian societies. Given that successful intercultural communication requires the speakers’ appreciation of their cultural diversities, while celebrating certain similarities, promoting learners’ cross-cultural awareness has become one of the important objectives of English language teaching in Asia. In this paper, I will draw on some sample analyses of Asian folktales which have been translated into English to (i) identify and explore the features of narrative structures and contents which can be seen as transcultural and others which can be highlighted as culture-specific, and (ii) discuss how such comparative analyses of narrative structures and contents in Asian folktales can be used to promote the cross-cultural awareness of English language learners in Asia. Implications for the socio-cultural-based English language teaching are offered.Â

Myanmar news summarization using different word representations

There is enormous amount information available in different forms of sources and genres. In order to extract useful information from a massive amount of data, automatic mechanism is required. The text summarization systems assist with content reduction keeping the important information and filtering the non-important parts of the text. Good document representation is really important in text summarization to get relevant information. Bag-of-words cannot give word similarity on syntactic and semantic relationship. Word embedding can give good document representation to capture and encode the semantic relation between words. Therefore, centroid based on word embedding representation is employed in this paper. Myanmar news summarization based on different word embedding is proposed. In this paper, Myanmar local and international news are summarized using centroid-based word embedding summarizer using the effectiveness of word representation approach, word embedding. Experiments were done on Myanmar local and international news dataset using different word embedding models and the results are compared with performance of bag-of-words summarization. Centroid summarization using word embedding performs comprehensively better than centroid summarization using bag-of-words

A Systematic Review on the Effectiveness of Different Functional Treatments for Acute Ankle Sprains

Background: An ankle sprain is a very common sport-related injury and can reduce participation in sports and employment. It can also create further complications in the function of the joint. Purpose: To evaluate the effectiveness of different functional treatments and to ascertain which functional treatment is the most effective method for acute ankle sprains. Study Design: Systematic review. Methods: The design of this systematic review was developed in accordance with PRISMA-P 2015 statement and performed according to its guidelines. A computerized literature search was performed from PubMed Central, MEDLINE via OVID and Cochrane library. Randomized controlled trials or quasi-experimental studies, published within a ten-year period (2007 to 2017), in peer-reviewed journals, with full-text articles and written in English were included in this study. Any type of functional treatments being applied to treat acute ankle sprains were considered as an intervention and only adult participants were included in this review. Surgical methods, unpublished trials, not written in the English language or not experimental research were excluded. Results: From the pooled data of this review, the stocking was more effective at improving pain, swelling, functional outcomes, range of motion, and return to sport/work, and had higher patient satisfaction than the bandage. There was no evidence that the taping and lace-up brace were more effective than other functional interventions in the treatment of acute ankle sprains. Furthermore, the prevalence of complications was greatest for the taping and lace-up brace interventions. The semi-rigid or posterior rigid support group had a better functional recovery and higher patient satisfaction, but some complications were present. Conclusion: The semi-rigid or posterior rigid support group and stocking were the most effective functional interventions for acute ankle sprain treatment. What is known about this subject: The functional treatments are becoming popular due to being effective, inexpensive and simplistic to apply. Different types of functional interventions have been used according to the choice of clinicians and patients in the treatment of ankle sprains. According to the previous researches, semi-rigid support, ankle braces, bandage and lace-up supports have greater advantages than other functional treatments from different perspectives (Example. the elastic bandage had a slower recovery rate than semi-rigid brace but less complications than taping, the lace-up support was better in swelling management than other functional treatments). What this study adds to existing knowledge: This study found that the stocking is an effective treatment for managing acute ankle sprains. It is valuable for the patient because the cost of the stocking is considerably cheaper than other functional treatments and it is very easy to wear. Some popular functional treatments like lace-up support; taping and semi-rigid braces were shown to have some complications

Hemoglobin E prevalence in malaria-endemic villages in Myanmar.

The population of Myanmar comprises 8 major indigenous races (Bamar, Kayin, Kachin, Shan, Rakhine, Mon, Chin, and Kayah). The Bamar reside in the 7 central divisions of the country, and the others reside in the 7 peripheral states that border neighboring countries, including China, Laos, and Thailand in the east and India and Bangladesh in the west. Both malaria and HbE are endemic in Myanmar, although the actual prevalence of the latter in the different indigenous races is not yet known. Hemoglobin electrophoresis was performed in 4 malaria-endemic villages, each having a different predominating indigenous race. The overall prevalence of HbE was 11.4% (52/456 villagers), ranging from 2-6% in the Kayin-predominant villages to 13.1-24.4% in the Bamar-predominant villages. Although the overall HbE prevalence in the villages studied was not significantly different from that of the general Myanmar population, this study strongly documented the influence of racial differences on the prevalence of HbE in Myanmar. To prevent and control severe thalassemia syndromes in Myanmar, extensive prevalence studies of the country?s indigenous races are suggested.</p

Commonly Used Instruments and Procedures in O&G”.

The book as a user-friendly handy and is mostly illustrated for the reader to understand the commonly used instruments and procedures in the field of basic Obstetrics and Gynaecology