20000 research outputs found
Sort by
Enhanced ferromagnetism in WS2 via defect engineering
No full textFerromagnetism in 2D materials has attracted extensive research interests. Defects are expected to play a pivotal role in the ferromagnetism based on theoretical calculations. However, there are few experimental results reported and mechanism of ferromagnetism associated with defects are not clear. In this paper, we employ WS2powders as an example to study the relationship between defects and magnetism by annealing the powders under reducing atmosphere. Magnetic measurements indicate that pristine WS2powders show weak ferromagnetism at room temperature. Compared to pristine WS2powder, annealed samples show significant enhancement of magnetization, which is strongly dependent on annealing temperature. The enhanced magnetization is attributed to defects induced by annealing, evidenced by X-ray photoelectron spectroscopy and electron paramagnetic resonance spectroscopy
Increased oxidative damage and premature placental aging contribute to the aetiology of stillbirth
No full textStillbirth is a neglected public health problem affecting more than two million women and families globally each year with devastating and long-lasting psychosocial and financial impact. Rates of stillbirth, even in high-income countries with access to optimal obstetric care, have remained static in the past two decades. The causes of, or associations with, stillbirth that have been identified clinically include fetal factors such as genetic/structural abnormalities and growth restriction, maternal factors such as preeclampsia and infections and placental factors such as abruption and placenta previa. However, no specific cause has been established for the majority of stillbirths at term, and the rate of this category of death rises drammatically as gestation progresses beyond 38 weeks. Taking into account the functional definition of aging that is an increase in the risk of death with time, and the existence of placental pathologies in the unexplained stillbirth pregnancies resembling aging in other organs, we hypothesise that premature placental aging may be the primary factor in the aetiology of unexplained stillbirth. Premature aging may occur when cells experience increased oxidative stress that causes damage to cellular macromolecules, including DNA, RNA and lipids, and alters protein expression patterns, especially those that are crucial for cellular survival and function. Therefore, the primary aim of this thesis was to investigate evidence that the placenta from late-gestation shows biochemical signs of oxidative damage and aging that would also be present in placentas associated with stillbirths. A further aim was to investigate the pathways that mediate the oxidative damage and aging in the placenta in pathologic pregnancies. We have shown that placentas from both late-term and stillbirth pregnancies show biochemical signs of aging in the form of increased DNA and lipid oxidation. Also, the expression of aldehyde oxidase 1 (AOX1), which is known to be involved in reactive oxygen species (ROS) generation and oxidative stress, is increased in placental tissues obtained from both late-gestation and stillbirth pregnancies. We tested the association of AOX1 in stillbirth pregnancy as an RNA sequencing study performed in our laboratory identified a significant increase in AOX1 mRNA in late-term placentas compared to term healthy placentas (unpublished). The demonstration of G-protein coupled estrogen receptor 1 (GPER1), a cell surface estrogen receptor, localisation on the apical surface of the normal placental syncytiotrophoblast and its role in the reduction of ROS generation and oxidative damage indicate that this receptor may be a critical step in the pathway of placental ROS induced oxidative damage. Using a placental explant and a cell line culture model, we then tested the pathways that regulate placental oxidative damage and aging. Results presented in this thesis revealed that growth factor removal resulted in placental oxidative damage, with impaired mitochondrial function, decreased expression of sirtuins (proteins that control aging), alteration of nutrient sensing mammalianTORC1, and energy sensing AMP activated protein kinase pathways, all the changes are known to be associated with oxidative damage and aging in other tissues. Inhibition of AOX1 or stimulation of estrogen activation at GPER1 resulted in the blocking of all the changes observed after removal of growth factors. Together, these findings support the hypothesis that placental oxidation is regulated by estrogen activation at the GPER1 and inhibition of AOX1 leading to the inhibition of ROS generation and oxidative stress. Our study identifies potential biomarkers of oxidative damage and aging in stillbirth placentas that raise the possibility that these biomarkers of placental oxidative damage and aging may be released into the maternal blood where they may have diagnostic value in predicting the fetus at risk for stillbirth. Treatment targeting AOX1 and/or GPER1 may arrest the oxidative damage in the placenta in pregnancies identified at risk and may lead to novel therapeutic strategies for delaying placental aging, as well as preventing stillbirth and other age-related adverse pregnancy outcomes
Effects of four different drying methods on the carotenoid composition and antioxidant capacity of dried Gac peel
No full textBackground: Gac fruit (Momordica cochinchinensis Spreng.) is a rich source of carotenoids for the manufacture of powder, oil and capsules for food, cosmetic and pharmaceutical uses. Currently, only the aril of the Gac fruit is processed and the peel, similar to the other components, is discarded, although it contains high level of carotenoids, which could be extracted for commercial use. In the present study, four different drying methods (hot‐air, vacuum, heat pump and freeze drying), different temperatures and drying times were investigated for producing dried Gac peel suitable for carotenoid extraction. Results: The drying methods and drying temperatures significantly affected the drying time, carotenoid content and antioxidant capacity of the dried Gac peel. Among the investigated drying methods, hot‐air drying at 80°C and vacuum drying at 50°C produced dried Gac peel that exhibited the highest retention of carotenoids and the strongest antioxidant capacity. Conclusion: Hot‐air drying at 80°C and vacuum drying at 50°C are recommended for the drying of Gac peel
What is "traditional cultural expression"? International definitions and their application in developing Asia
No full textThe WIPO Intergovernmental Committee on Intellectual Property and Genetic Resources, Traditional Knowledge and Folklore (IGC) began its deliberations in 2001. Eight years later in July 2009, it reached a temporary standstill. At its 14th session, held in Geneva from June 29 to July 3, 2009, representatives of Members States, intergovernmental and non-governmental organisations agreed to disagree on the agenda item related to ‘‘Future Work’’ that attempted to specify ways in which the work of the Committee should be carried forward during the 2010–11 biennium. Representatives of many developing countries and non-governmental organisations voiced their dissatisfaction with the slow progress in the IGC. A proposal from the African Group of countries sought to speed up the agenda during the 2010–11 biennium by requiring ‘‘text-based negotiations’’ for ‘‘an internationally binding instrument/instruments’’ with a ‘‘clearly defined work programme and timeframe, including the holding of intersessional work sessions’’. While this proposal was supported by a large number of developing country representatives, others such as the representatives of the United States, Japan or Germany, speaking on behalf of the B Group of developed countries, found still much ‘‘unfinished analytical work’’ and the necessity to further a ‘‘common understanding’’ of the issues. Thus, while members were clearly in favour of renewing the mandate of the IGC, there were differing views on the precise scope and aims of its work during the next biennium. The idea of intersessional work sessions and of a partial shift of forum to expert working groups as well as the composition of such groups was also disputed. At their Annual Assemblies from September 22 to October 1, 2009, WIPO member states finally renewed the mandate of the IGC with the objective of reaching agreement on a text of an international legal instrument (or instruments) and with a provision for three inter-sessional meetings of working groups. One of the ongoing discussions concerns definitions of ‘‘traditional cultural expressions’’, which will be the focus of the first part of this article. IGC members in fact also disagreed on whether more consensus on fundamental concepts and ‘‘broad, non-exhaustive and non-exclusive, definitions’’ was necessary or whether it was possible to start with more loosely worded terminology in order not to get ‘‘stuck in working on ideal definitions that could take years to adopt’’. The article will then examine the approach to TCE protection in Indonesia and a few disputes between Indonesia and Malaysia about TCEs
Mapping multidecadal morphological variabilty via satellite derived bathymetries
No full textThis paper outlines a novel approach to calibrating satellite derived relative depth surfaces generated using the ratio transform algorithm first proposed by Stumpf et al. The method utilizes raster image equal interval classification to generate depth classes and to identify both the upper and lower limits of sensitivity to the depth signal within the relative depth models. The method was trialed on a multidecadal set of Landsat images for a coastal compartment on the SE Australian coast. [Final citation details to be advised.
Understanding the changes of designers’ behaviours when using mixed media design environments
No full textDesigners’ interactions with design media have shifted from individual to multiple design media to improve design activities and outcomes. This transition is mainly in response to the increased globalisation of design projects. However, many mixed media studies have adopted a linear approach and focused on evaluating design solutions from different design media as opposed to design processes. Different uses of design media during designing may influence designers’ cognition and design processes. In previous mixed media empirical studies, designers were asked to initially use traditional sketching before shifting to CAD modelling. For the purpose of the study, this use of mixed media, in which one shift between media occurs, is defined as Sequential Mixed Media (SMM). However, designers prefer to interact freely between media, alternating between sketching and CAD modelling as it suits them. This approach is termed Alternative Mixed Media (AMM) and is currently the most popular among designers and design students. This study seeks to address a lack of evaluation with the AMM approach by investigating the impacts of switching between different design media on designers' cognition and creative design processes. Literature about design activities in mixed media environments mainly focuses on design outcomes using SMM. There have been few AMM studies that explore the roles of sketching and CAD modelling and how switching behaviours impact on designers’ cognition and creative design processes. This study compares two different approaches of interacting with sketching and CAD modelling (SMM versus AMM) to elucidate how switching behaviours impact on designers’ cognition and creative design processes. Many studies show that protocol analysis is effective in recording designers’ reasoning during the design process. Research questions about whether switching behaviours impact on designers’ cognition and creative design processes remain unanswered. Protocol analysis was used to facilitate controlled observations and experimental analyses to investigate the research questions and objectives. The main study contains three parts: the SMM study, the AMM study, and SMM versus AMM study. The results of the SMM study with four participants show that dissatisfaction with sketches resulted in CAD modelling being used to support conceptual design. Being dissatisfied with sketches, the whole CAD design phase became uncertain. This played a key role driving designers to new solutions and involved considerable cognitive effort on evaluation. The results of the AMM study with six participants show that both sketching and CAD modelling play a markedly similar role. A switching behaviour model was proposed containing eyes’ switching, single switching and integrated switching. These behaviours appropriately supported designers in the design process. Concept-level switching behaviour can integrate two design media into one design medium. Concept-level switching behaviour has considerable potential to transform design processes into creative design processes. The results of the SMM versus AMM study with eight participants show that there is no significant difference between sketching and CAD modelling. One of the difficulties experienced was that the think-aloud method used to collect data was unable to capture participants’ thoughts about switches because each switch takes only a few milliseconds. Participants were subsequently interviewed about each switch and reminded about their design activities using video recordings. Their reflections were collected on completion of their design tasks. Six of the eight participants strongly believed that switching behaviour is essential to use the advantages of both media, and to use each one to counter the weaknesses of the other. This research is a thesis by publication, comprising an introduction, literature review, methodology, discussion, conclusion, and seven publications. Paper One provides the framework and identifies a gap for a mixed media design study that developed as part of the overall study. Paper Two expands upon the literature reviewed in Paper One. It covers different types of design media research and focusses on switching behaviour in mixed media design environments. Paper Three builds upon the research design section described in Paper Two and reports the conduct of a pilot study. Paper Four expands on Paper Three to solidify the preliminary outcomes. Paper Five further explores Paper Four involving four designers to focus on the roles of design media using the SMM approach as part of a main study. Paper Five expands upon Paper Four involving six participants using the AMM approach to solidify the analysis of design activities as well as of switching behaviours as a part of the main study. Paper Seven expands upon Paper Five and Paper Six to solidify the main study outcomes involving eight participants using both SMM and AMM approaches. The outcomes are discussed in relation to two aspects: the roles of design media and designers' reflections. This study used two approaches in this mixed media research: the SMM and AMM. The aim of this study is to investigate the impact of switching behaviours on designers’ cognition and creative design processes. The SMM approach was conducted as a baseline to compare participants’ design activities and their reflections. Based on the reflections, switching behaviours not only allowed for a more accurate testing of conceptual sketches but also facilitated the enhancement of designs. Switching behaviours were found to support designers by allowing them to: (i) make appropriate design decisions; (ii) enhance co-evolution; and (iii) provide a natural design workflow. Based on an analysis of design activities, switching behaviours supported designers’ perceptions, media and concept levels during their design activities
Decentralized control for l₂ weak string stability of vehicle platoon
No full textIn this paper we present a method of bidirectional control of a vehicle string that achieves l2 weak string stability. Previous work required short-range communications between vehicles within the string. Here, we utilise some recent results on integral action to remove the requirement of communications altogether
Activation of the absent in melanoma 2 inflammasome in peripheral blood mononuclear cells from idiopathic pulmonary fibrosis patients leads to the release of pro-fibrotic mediators
No full textIdiopathic pulmonary fibrosis (IPF) is a chronic fibro-proliferative disease characterized by poor prognosis, with a mean survival of ~2–3 years after definite diagnosis. The cause of IPF is still unknown but it is a heterogeneous condition in which the aberrant deposition of extracellular matrix leads to extensive lung remodeling. This remodeling is a consequence of inflammatory responses, but the mechanisms involved are poorly understood. In this study, we first analyzed a bleomycin-induced mouse model, which showed that higher expression of IL-1β, but not IL-18, was correlated to pulmonary cell infiltration and fibrosis. Then, we found that peripheral blood mononuclear cells (PBMCs) from IPF patients released IL-1α and IL-18 in a NLRP3- and calpain-independent manner after LPS ± ATP stimulation. Instead, the activation of the absent in melanoma 2 (AIM2) inflammasome induced the release of IL-1α in a caspase-1-/caspase-8-independent manner; whereas IL-18 release was caspase-1 dependent. These effects correlated with the release of the pro-fibrotic TGF-β, which was induced by AIM2 activation in a caspase-1- and TLR4-independent manner, but dependent on IL-1α. In this context, the activation of AIM2 induced the release of caspase-4 from IPF-derived PBMCs, which correlated with the mRNA levels of this caspase that was higher in IPF than in healthy PBMCs. In conclusion, our findings identify a novel molecular mechanism whereby the activation of AIM2 could lead to the activation of the non-canonical inflammasome (caspase-4 dependent) that induces the release of IL-1α responsible for the release of TGF-β from PBMCs of IPF patients
Study on the heterogeneous catalytic hydroesterification of varying oil types to develop an understanding of FAME Formation
No full textBiodiesel, comprised of fatty acid alkyl esters, can be produced from renewable and waste feedstocks and can replace or used as a blend with fossil fuel based petroleum products. Hydroesterification is relatively new and evolving technology for biodiesel synthesis, which is not susceptible to many of the disadvantages of the traditional transesterification process used for biodiesel production. Producing biodiesel via hydroesterification is a two-step process which involves the hydrolysis of the oil feedstock and esterification of the free fatty acids thus produced. The elimination of foaming problems and obviating the deleterious effect of moisture and acidity level of the feedstocks are the main (potential) advantages of the
hydroesterification over transesterification. In addition to these advantages, the production of a high purity (and thus high value) glycerol as the primary hydrolysis product stream and the recovery of water from esterification step are additional important advantages of the hydroesterification process that can offset the cost of biodiesel production. Heterogeneous catalysts have the important advantages of being readily separated from the feed and products of reaction by filtration and they can be reused. Zeolites, as porous crystalline aluminosilicate structures with pores that are interconnected to smaller internal channels, have significant adsorption capacities and can be used as catalysts for many chemical reactions. Aluminium atoms located in zeolite framework and located in the zeolite pores provide the Brønsted acid sites which are sites deemed responsible for zeolite activity. This thesis investigates the heterogeneously catalysed hydroesterification of various oils to develop an understanding of hydroesterification biodiesel synthesis process. HBEA zeolite displayed high catalytic activity for biodiesel synthesis via hydroesterification. At low temperatures (T3-TPD results showed that zeolites with lower Si/Al ratio have larger number of Brønsted acid sites rendering them as highly hydrophilic but reducing the average strength of their acid sites. Although a greater number of Brønsted acid sites improves the conversion level, the catalyst efficiency, describes in terms of a turnover frequency
(TOF), is decreased as the lower strength of the acid sites increases the rate of zeolite deactivation with water. A higher Si/Al ratio in the zeolite induces a greater level of hydrophobicity to the zeolite that in turn leads into higher affinity for the oil and fatty acid molecules to be adsorbed onto the zeolite, and lowers the rate of deactivation due to adsorption of water on to the active site. For both hydrolysis and esterification reactions, HBEA (Si/Al=175) with highest Si/Al ratio showed significantly higher specific rate of reaction (TOF) comparing to the lowest Si/Al ratio zeolite used HY (Si/Al=6).The influence of reaction variables show that presence of acid sites and reaction temperature and stirring rate are the primary, dominating factors for preferred catalytic performance. The potential of zeolite regeneration via thermal treatment was also confirmed, as more than 95% of the original zeolite activity was recovered over a zeolite recalcined at 450 ºC in air. Conducting hydroesterification reactions at various stirring rates from 60 to 600 rpm it was concluded that external mass transfer did not have a significant influence on the observed reaction rate. In addition, conducting reactions over various zeolites at carefully controlled particle sizes ranges (bins), from 50 to 600 μm, no substantial change in the conversion level was observed, which is indicative of the absence of any significant internal mass transfer limitation on the observed reaction rate. The values of Thiele modulus, estimated to be less than 0.4, and rather high activation energy values, 25.9 kJ/mol for hydrolysis and 24.8 kJ/mol for esterification, confirms the kinetically controlled reactions occurring in the absence of significant diffusion limitations. The FTIR analysis indicates the hydrogen bonding interaction of hydroxyl groups of zeolite, which acts as a proton donors, with the both surrogate ester (ethyl acetate)
and fatty acid (acetic acid) molecules. The protonation of carbonyl group is also evident via hydrogen bonding with bridging O-H in Si-OH-Al groups (Bronsted acid sites) of the zeolite
Emergency navigation without an infrastructure
No full textEmergency navigation systems for buildings and other built environments, such as sport arenas or shopping centres, typically rely on simple sensor networks to detect emergencies and, then, provide automatic signs to direct the evacuees. The major drawbacks of such static wireless sensor network (WSN)-based emergency navigation systems are the very limited computing capacity, which makes adaptivity very difficult, and the restricted battery power, due to the low cost of sensor nodes for unattended operation. If static wireless sensor networks and cloud-computing can be integrated, then intensive computations that are needed to determine optimal evacuation routes in the presence of time-varying hazards can be offloaded to the cloud, but the disadvantages of limited battery life-time at the client side, as well as the high likelihood of system malfunction during an emergency still remain. By making use of the powerful sensing ability of smart phones, which are increasingly ubiquitous, this paper presents a cloud-enabled indoor emergency navigation framework to direct evacuees in a coordinated fashion and to improve the reliability and resilience for both communication and localization. By combining social potential fields (SPF) and a cognitive packet network (CPN)-based algorithm, evacuees are guided to exits in dynamic loose clusters. Rather than relying on a conventional telecommunications infrastructure, we suggest an ad hoc cognitive packet network (AHCPN)-based protocol to adaptively search optimal communication routes between portable devices and the network egress nodes that provide access to cloud servers, in a manner that spares the remaining battery power of smart phones and minimizes the time latency. Experimental results through detailed simulations indicate that smart human motion and smart network management can increase the survival rate of evacuees and reduce the number of drained smart phones in an evacuation proces