3,472 research outputs found
Defining and evaluating learner experience for social adaptive e-learning
No full textSocial adaptive e-learning combines, threads and balances the amount of social and adaptive features for e-learning in order to achieve high-quality Learner eXperience (LX). Evaluating a social adaptive e-learning system is a difficult task due to its complexity. It is crucial to ensure that appropriate evaluation methods and measures are used. A User-centric approach serves the empirical system evaluation using subjective user feedback on satisfaction and productivity as well as the quality of work and support, so as to verify the quality of product, detect problems, and support decisions. This paper proposes a learner-centric evaluation framework, which applies a user-centric approach, aiming to evaluate LX in social adaptive e-learning from the end-user (learner) point of view, taking into consideration both social and adaptive perspectives
Langmuir and LB properties of two calix[4]resorcinarenes: Interactions with various analytes
No full textThe ability of calixarene-based molecules to interact with amino acids has been
the basis of many studies. The Langmuir and LB properties of two calix
[4]resorcinarenes have been investigated. The properties of the layer formed at
the air–water interface were studied by surface pressure–area isotherms. LB
deposition onto glass substrates has shown that multilayer assemblies can be
built up. The UV–vis spectra of resulting LB films have been recorded,
indicating that the compounds are coloured as a result of intra-molecular charge
transfer bands. The sensitivity of the surface pressure–area isotherms has been
investigated in relation to the exposure to various analytes delivered from the
subphase (i.e. amino acids). Furthermore, exposure of the LB films to a wide
range of vapours (e.g. amines, alcohols, thiols) has led to modified UV–v
Photoelectro-chemical properties of anilino squaraine derivatives in LB films
No full textPhotocurrent generation from Langmuir-Blodgett (LB) overlays on indium tin oxide (ITO) electrodes, where the active components are 2,4-bis[4-(dibutylamino)-2-hydroxyphenyl]squaraine (1) and the unsubstituted analogue, 2,4-bis[4-(dibutylamino)phenyl]squaraine (2), have been investigated. Dye 1 shows improved behaviour compared with the latter and differences in performance are attributed to a modified aggregate structure, this being indicated by variations in the LB film spectra. The photocurrent generation is enhanced by the presence of electron accepters, e.g. N,N'-dimethyl-4,4'-bipyridinium diiodide (MV2+), but quenched by electron donors, e.g. hydroquinone (HQ). The concentration dependence is reported
Biogenesis and transmembrane topology of the CHIP28 water channel at the endoplasmic reticulum
No full textCHIP28 is a 28-kD hydrophobic integral membrane protein that functions as a water channel in erythrocytes and renal tubule epithelial cell membranes. We examined the transmembrane topology of CHIP28 in the ER by engineering a reporter of translocation (derived from bovine prolactin) into nine sequential sites in the CHIP28 coding region. The resulting chimeras were expressed in Xenopus oocytes, and the topology of the reporter with respect to the ER membrane was determined by protease sensitivity. We found that although hydropathy analysis predicted up to seven potential transmembrane regions, CHIP28 spanned the membrane only four times. Two putative transmembrane helices, residues 52-68 and 143-157, reside on the lumenal and cytosolic surfaces of the ER membrane, respectively. Topology derived from these chimeric proteins was supported by cell-free translation of five truncated CHIP28 cDNAs, by N-linked glycosylation at an engineered consensus site in native CHIP28 (residue His69), and by epitope tagging of the CHIP28 amino terminus. Defined protein chimeras were used to identify internal sequences that direct events of CHIP28 topogenesis. A signal sequence located within the first 52 residues initiated nascent chain translocation into the ER lumen. A stop transfer sequence located in the hydrophobic region from residues 90-120 terminated ongoing translocation. A second internal signal sequence, residues 155-186, reinitiated translocation of a COOH-terminal domain (residues 186-210) into the ER lumen. Integration of the nascent chain into the ER membrane occurred after synthesis of 107 residues and required the presence of two membrane-spanning regions. From this data, we propose a structural model for CHIP28 at the ER membrane in which four membrane-spanning alpha-helices form a central aqueous channel through the lipid bilayer and create a pathway for water transport
Comments on author citations for nomenclatural novelties published in volume 15 of the Flora Reipublicae Popularis Sinicae (FRPS)
No full textMaking it game-like : Topolor 2 and gamified social e-learning
No full textThis paper briefly introduces Topolor 2, a social personalised adaptive e-learning environment with novel gamification features, aiming at reducing undesirable 'noise' effects of social interaction and at further improving the learning experience. The goal of this paper is to showcase the main gamified social interaction features
From defect to design feature: optimising LB-PBF-induced porosity for altering tribological behaviours of cocrmo surfaces for orthopaedic applications
No full textAdditive manufacturing has expanded the design possibilities for orthopaedic implants, enabling complex geometries and patient-specific customisation that are difficult to achieve with conventional manufacturing. Among these techniques, Laser Beam Powder Bed Fusion (LB-PBF) has been widely adopted for processing metals. Cobalt-chromium-molybdenum (CoCrMo) alloys have been the standard bearing material in many designs of artificial hip joints for their high mechanical strength and wear resistance. Despite extensive work on LB-PBF mechanical properties and on the tribology of conventionally manufactured CoCrMo, the tribology of LB-PBF CoCrMo remains not well understood. Porosity is an intrinsic feature of LB-PBF, arising from the interaction of process parameters and thermal histories. In the context of articulating surfaces, LB-PBF process-induced pores represent a microstructural feature whose effects on tribological performances have yet to be fully defined. Understanding whether such features behave as defects to be eliminated or as functional surface textures with potential performance benefits requires a combined additive manufacturing-tribology approach. This thesis addresses this gap by progressing from elucidating fundamental process-structure relationships, through assessing tribological behaviours of LB-PBF CoCrMo, to demonstrating the feasibility of manufacturing bearing surfaces with spatially tailored porosity. The results demonstrate that LB-PBF process-induced porosity in CoCrMo can be systematically controlled through the combined effects of process parameters, enabling porosity levels ranging from near-dense to highly porous. Tribological evaluation showed that the effects of porosity are strongly affected by lubrication conditions: under protein-rich lubrication, friction and wear performance depend on the porosity level, whereas under water lubrication, higher porosity led to increased friction and apparent wear volume loss. The fabrication and testing of hybrid bearing surfaces with locally engineered porosity revealed that spatial porosity contrasts introduced additional complexity and increased frictional variability and wear. The outcomes provide a foundation for optimising LB-PBF processing strategies and exploring new design approaches for orthopaedic implants.Open Acces
To build light gamification upon social interactions : requirement analysis for the next version of Topolor
No full textThe introduction of social dimension enables traditional adaptive educational hypermedia systems to provide more versatile personalized services. Topolor has been developed to investigate the impacts of social
interaction and feasible engagement strategies in such a system. We have evaluated Topolor’s social features from the perspectives of usefulness and ease of use. We intend to develop the next version of Topolor, starting with enhancing relatively lower rated social features. This paper presents our plan of building light gamification upon the evaluated social interaction features with relatively lower rating
Photoelectric conversion property of monolayer films of fullerene tetracarboxylic acid derivatives
No full textAn amphiphilic C-60 tetracarboxylic acid (1) and its tetramethyl eater (2) have been prepared. They form stable Langmuir monolayer at the air-water interface, which can be deposited on semiconducting transparent ITO electrodes. The photoelectric responses of the monolayer-modified electrodes are measured in a conventional photoelectrochemical cell. The anodic photocurrent observed corresponds to an electron transfer from the electrolyte through LB film to the electrode. The action spectrum of the photocurrent is in good agreement with the absorption spectrum of the modified ITO electrode, confirming that the excited C-60 derivatives act as the photoactive species in the photoinduced electron transfer process. Factors influencing the photocurrent have been studied such as the intensity of the irradiation, concentration of redox agent in the electrolyte solution, bias voltage and pH. (C) 1999 Elsevier Science S.A. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000082709600035&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Materials Science, MultidisciplinaryMaterials Science, Coatings & FilmsPhysics, AppliedPhysics, Condensed MatterSCI(E)2ARTICLE1-2218-22235
Evaluation of social interaction features in topolor - a social personalized adaptive e-learning system
No full textHere we present a case study that analyses the social interaction features in Topolor, an adaptive personalized social e-learning system. This paper focuses on the evaluation of the perceived usefulness and usability. The results show a considerably high satisfaction of the students. We discuss the evaluation results and outline the plan for improvement
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