Experimentally characterizing the behavior of fiber reinforced composite laminates under multi-axial loading: A historical review and current state of the art

The mechanical behaviour of fibre reinforced composite laminates under applied loading is a complex process due to a variety of factors including geometry effects at various scales (micro-, meso- and macro-level), complex constitutive responses, and the interaction and competition between progressive damage modes. While the study of fibre reinforced composite laminates under multi-axial loading conditions has been an area of study for over 40 years, the number of experimental studies is limited primarily due to the difficulty in performing relevant experiments. The importance of these types of experiments, however, is critical to help advance the understanding and prediction of laminate response and failure. Improved understanding and predictive capabilities will ultimately lead to the future development of more advanced (and practical) tools which can reduce the cost and effort in designing and qualifying new composite structures

Content Knowledge Development Needs of Pre-service Teachers in Bhutan Based on the Primary Mathematics Curriculum: An application of SOLO

The mathematics curriculum in Bhutan has undergone significant change over last 20 years, moving from behaviourist teaching and learning strategies towards a constructivist focus by teachers. In 2005, a new national mathematics curriculum in schools was implemented nationwide. When planning for the new curriculum to have a significant impact on the education system many factors were considered such as: teachers’ attitudes, teachers’ content knowledge and pedagogical knowledge, teachers’ perceptions, availability of teaching and learning materials, classroom settings, and preparation of pre-service teachers (PSTs). Teachers across the country were oriented through workshops to learn about the new curriculum, and new textbooks, guidebooks and workbooks were developed and made available to schools. Now there are concerns that these reforms, as significant and necessary as they were, are not delivering the student outcomes (BCSEA, 2011, 2013, 2017) that would best serve the country through the 21st Century. Needed are studies that chose to identify important issues they may be impeding student learning and offer evidenced informed suggestions on possible ways to enhance the education system. This study was undertaken with this goal in mind. The purpose of the study was to investigate the mathematics content knowledge of PSTs in terms of the mathematics in the primary school mathematics curriculum. Such a study had not been undertaken previously in the Bhutanese context. The focus of the research was on (i) investigating the breadth and depth of primary mathematics curriculum content knowledge of PSTs with the purpose of seeking out their ‘development needs’; and (ii) how might the data collected be a basis for enhancing the quality of teacher education preparation in primary mathematics in Bhutan. There are two theoretical underpinnings of the study. The first is the Mathematical Knowledge for Teaching (MKT) model of Ball et al. (2008) based on Lee Shulman’s pedagogical content knowledge – mathematical knowledge needed to carry out the work of teaching mathematics. The second is the Structure of the Observed Learning Outcome (SOLO) model (Biggs and Collis, 1982) – a post-Piagetian analytical tool used to determine the quality of a student’s response to a task in any learned activity. The study data were collected using a survey and interviews. The survey instrument consisted of 40 multiple-choice items (MCIs) and six free response questions (FRQs), covering the first four strands (Numbers Strand, Operations Strand, Patterns Strand and Measurement Strand) of the primary mathematics curriculum. Using the explanatory sequential mixed-methods design, data were collected from 3rd Year and 4th Year PSTs from the two teacher training colleges in Bhutan (n=234). The quantitative data collected through MCIs were analysed using the Rasch model. The qualitative data collected through FRQs was analysed using the SOLO Model and was further interrogated through interviews undertaken with a sample of PSTs. The Rasch analysis of the survey instrument (MCIs) used both the binary model and partial credit model. For the binary model, PSTs’ responses were marked as either correct or incorrect. For the partial credit model, PSTs were given credit for partially correct answers to items. Both models demonstrated high reliability estimates for the survey instrument (MCIs). To facilitate discussion on PST developmental growth further, five broad bands were identified in the MCI difficulty estimates and PST ability estimates. Boundaries between bands were evident by clear separations in the item map. The approach identified groups of responses (items) upon which generalisations about the nature of the items and what PSTs could achieve. Band 5 (highest-level) characteristics comprised approximately 4% of the PST cohort. The next band, band 4, comprised approximately 12% of the PST cohort. Nearly 80% of PSTs were not able to answer correctly 16 items of the forty-item test. It was found that the inability to utilise all needed information in a question, inadequate conceptual understanding and unfamiliar context of the questions may have escalated the difficulty level of items. Some PSTs demonstrated abstract and high-level thinking in primary mathematics content. This was evident in the approaches used in solving abstract and non-routine questions. PSTs going beyond what was asked in the questions and using adequate and appropriate ways of solving the questions are some positive findings. PSTs performed better when the questions were straightforward, familiar and where all the required information was available in the question. This indicates PSTs acquired procedural knowledge linked to practised situations, and encountered difficulties when the question/item focused deliberately on conceptual knowledge or in which conceptual knowledge was needed as a tool in the solution process. Areas where the majority of PSTs needed support to enhance their content knowledge included many arithmetic concepts that were basic to primary school mathematics, such as place value, pattern recognition, comparing fractions, determining equivalent fractions, ratio and not being able to make connections among the parts of division operation (dividend, divisor, quotient and remainder). The study also found that the majority of the PSTs lack conceptual understanding of concepts of area and perimeter. For instance, when finding the area of shapes such as triangles of non-rectilinear shapes many students applied the area formula of a rectangle (length × breadth). Overall, the study found that only a small number of PSTs had acquired adequate breadth and depth of primary mathematics content knowledge across all four strands. This was indicated by the large numbers of partially correct responses in both MCIs and FRQs across all four strands. The majority of the PSTs attained content knowledge at a surface level which did not appear to be an appropriate basis for teaching. In addition, knowledge gaps in all four strands were evident. The findings highlight a major challenge for the colleges of education in Bhutan. The majority of the PSTs struggled with the fundamental knowledge, skills and understanding in primary mathematics. Without this, it appears problematic that new primary teachers will be capable of meeting the learning needs of their students

ShamanSpeak: The Storytellers of the Earth

This thesis, informed by the philosophy of phenomenology, examines the nature of the relationship between Storytellers and the Earth which they speak for. The aim of the study was to explore the essence that draws these Storytellers into a relationship with the Earth. Through reflection on the experience of their connection to the Earth, on their experience of being a Storyteller of the Earth, and on their place within the cycle of the Earth, a story evolved. Their role and relationship as Storytellers was envisioned as a kind of medium between the Earth that was 'out there' beyond the wall or edge of civilisation, and the civilisation that they sought to raise awareness within. Drawing on the archetypes of history and myth, the term Shamans seemed appropriate to describe them. From their voice came this thesis ShamanSpeak: the Storytellers of the Earth, in which more traditional academic analysis is complemented by a recorded album of songs which the interviewee's words inspired

Fibre Reinforced Composites in Pipeline Applications: Design Issues and Current Research

Fibre reinforced polymeric composites used in pressure retaining structures are seen as an attractive alternative to products made from conventional materials due to their corrosion resistance and high strength-to-weight ratio. The reluctance in adopting composite materials, however, is due to a limited understanding of the material behaviour under a variety of loading and environmental conditions, and lack of qualified design methodologies. It is the purpose of this paper to address fundamental and applied issues regarding their feasibility and current limitations in pipeline applications. A review of pertinent research results with respect to the local and global behaviour in composite pipes will be discussed.Copyright © 2000 by ASM

Effect of Labelling and Information on Consumer Perception of Foods Presented as 3D Printed

Labelling and information have been shown to increase acceptance of novel food technologies. The novel technology of 3 Dimensional Printing (3DP) of foods is not well known among consumers. The study aim was to investigate the effect of the 3DP label and benefits information on consumer acceptance and perception of plausible 3DP foods. Commercially available foods, such as milk chocolate swirls, gummy candy carrots, and baked potato Smiles®, represented 3DP benefits, and each was evaluated in a sensory panel. Participants rated acceptance and perceived quality after each of three product presentations; first labeled “conventional”, then labeled “3D printed”, and again labeled 3D printed after information presentation. Participants indicated product preference after the third presentation. Food Technology Neophobia (FTN), attitude, and previous 3DP knowledge were queried. Quality rating of chocolate swirls and gummy candy carrots increased when labeled as 3DP versus conventional; information did not further increase quality ratings. Participants preferred 3DP chocolate swirls and gummy candy carrots to conventional in the final evaluation. Label and information did not change flavor, texture, or overall acceptance ratings for any product. Attitude towards 3DP of foods increased with lower FTN. Future studies could tailor information to consumer interests and knowledge gaps that highlight relevant benefits of 3DP

Influence of Selected Product and Process Parameters on Microstructure, Rheological, and Textural Properties of 3D Printed Cookies

One of the major advantages of 3D food printing is the customizability in terms of structure, design, and nutritional content. However, printability of the ingredients and the quality of the 3D printed food products are dependent on several product and printing parameters. In this study, nutrient dense cookies were developed with underutilized ingredients including jackfruit seed powder and finger millet powder as base materials using 3D food printing. The hardness, rheological behavior, and microstructure of 3D printed cookies with different products (e.g., water butter ratio) and printing (e.g., fill density and temperature) parameters were analyzed. The 3D printed cookies were developed by extruding at 27 and 30 °C with fill density values of 50%, 70%, 90%, and 100% and water butter ratios of 3:10 and 6:5. The 3D-printed cookie dough exhibited a more elastic behavior with higher storage modulus values than the loss modulus. The hardness of the baked cookies was influenced by printing temperature, fill density, and water butter ratio of 3D printed cookie dough and their interactions. The closed porosity of 3D printed cookies increased while the open porosity decreased with an increase in fill density. The baking times required were longer for 3D-printed cookies with higher fill density values. Overall, this study shows the importance of considering the specific ingredient and printing parameters to develop high quality 3D-printed cookies

Molecular Characterization of a Heteromeric ATP-Citrate Lyase That Generates Cytosolic Acetyl-Coenzyme A in Arabidopsis

Acetyl-coenzyme A (CoA) is used in the cytosol of plant cells for the synthesis of a diverse set of phytochemicals including waxes, isoprenoids, stilbenes, and flavonoids. The source of cytosolic acetyl-CoA is unclear. We identified two Arabidopsis cDNAs that encode proteins similar to the amino and carboxy portions of human ATP-citrate lyase (ACL). Coexpression of these cDNAs in yeast (Saccharomyces cerevisiae) confers ACL activity, indicating that both the Arabidopsis genes are required for ACL activity. Arabidopsis ACL is a heteromeric enzyme composed of two distinct subunits, ACLA (45 kD) and ACLB (65 kD). The holoprotein has a molecular mass of 500 kD, which corresponds to a heterooctomer with an A(4)B(4) configuration. ACL activity and the ACLA and ACLB polypeptides are located in the cytosol, consistent with the lack of targeting peptides in the ACLA and ACLB sequences. In the Arabidopsis genome, three genes encode for the ACLA subunit (ACLA-1, At1g10670; ACLA-2, At1g60810; and ACLA-3, At1g09430), and two genes encode the ACLB subunit (ACLB-1, At3g06650 and ACLB-2, At5g49460). The ACLA and ACLB mRNAs accumulate in coordinated spatial and temporal patterns during plant development. This complex accumulation pattern is consistent with the predicted physiological needs for cytosolic acetyl-CoA, and is closely coordinated with the accumulation pattern of cytosolic acetyl-CoA carboxylase, an enzyme using cytosolic acetyl-CoA as a substrate. Taken together, these results indicate that ACL, encoded by the ACLA and ACLB genes of Arabidopsis, generates cytosolic acetyl-CoA. The heteromeric organization of this enzyme is common to green plants (including Chlorophyceae, Marchantimorpha, Bryopsida, Pinaceae, monocotyledons, and eudicots), species of fungi, Glaucophytes, Chlamydomonas, and prokaryotes. In contrast, all known animal ACL enzymes have a homomeric structure, indicating that a evolutionary fusion of the ACLA and ACLB genes probably occurred early in the evolutionary history of this kingdom