6,798 research outputs found
Implications of the Improvement of Teaching Quality for Professional Development (PD) of Academics at the Colleges of Applied Sciences (CASs) in the Sultanate of Oman
No full textThe Oman Accreditation Council (OAC), which is called later the Oman Academic Accreditation Authority (OAAA), designed a higher education institution (HEI) Quality Assurance (QA) framework for Omani public and private Higher Education Institutions (HEIs), starting with a quality audit process in 2008. The Colleges of Applied Sciences (CASs), as a public HEI, are required to ensure the quality of all services and activities to meet particular national standards (specified in the framework) in order to gain a HEI and programme certificate. In line with a quality audit scope, the quality of the fields of PD and related teaching quality should be ensured and enhanced by the promotion and contribution of the former field to the maintenance and improvement of the latter one.
The chief purpose of this study was to identify the uptake and implications of the growing requirement to improve teaching quality and the PD of academics at the CASs in the Sultanate of Oman especially in the context of the application of the QA framework. The study focused on examining the academics’ participation in professional development programmes (PDPs) and current perceptions of PD with respect to the improvement of teaching quality improvement at these colleges. The current study also dealt with a reorganization and prioritization of academics’ PD needs, barriers to effective PD, and factors to enhance PD of academics regarding teaching quality improvement in the colleges.
Based on the purpose and research objectives, the current study adopted both positivist (quantitative) and interpretive (qualitative) research paradigms. Because the study perused quantitative and qualitative data regarding certain variables, it chose a mixed-research design. The researcher designed survey questionnaire to collect quantitative data and a semi-structured interview and a focus group discussion to probe and interpret quantitative findings. After fulfillment of the validity and reliability measurements, a self-completion questionnaire was distributed to a stratified random sample of academics (170) over the six CASs. A total of 150 questionnaires (out of 170) were completed and returned and the response-rate reached 88.2%. The quantitative data was analyzed by appropriate analysis using the Statistical Package for Social sciences (SPSS), while the qualitative data was analyzed by appropriate qualitative analysis.
The findings of the study showed that the level of academics’ participation in PDPs to improve teaching quality in the last two years in the CASs seems to be unsatisfactorily low. The current perceptions of the PD situations in the colleges, relating to teaching quality improvement, signified a shortage in the number of available PDPs and/or a discouragement of academics’ participation in these programmes in the last two years. The study also revealed all the 22 PD needs of academics regarding the improvement of teaching quality are significantly demanded by participants; the higher rated needs focused on a development of ‘student centred’ skills, such as critical thinking and problem-solving skills.
Furthermore, the study illustrated that the highest significant perceived barriers to effective PD in the CASs, as related to teaching quality improvement, focus on a lack of a clear institutional PD policy and a lack of appropriately systematic PD plans. The study also revealed all 10 perceived factors to enhance PD regarding teaching quality improvement are very important. The most significant factors represented and stressed particular problematic issues (the high rated barriers) and a reduction of a heavy workload to enhance academics’ participation in PD regarding the improvement of teaching quality.
Conclusions drawn from the discussion of the findings of study include a lack of a clear PD policy at national and institutional levels and absence of a particular authority/unit concerning PD issues in Omani HEIs. The two problematic issues resulted in a lack of systematic and realistic PD plans in the CASs, involving a lack of academics’ involvement in PD plans, a misconnection of academics’ PD needs to PD, inappropriate facilities and resources allocation, and inappropriate evaluation processes of PD. In addition, the conclusions also include that PD of academics regarding the improvement of teaching quality in the colleges requires more attention and focus to manage particular significant issues perceived by participants as both barriers and potential facilitators relating to PD of academics.
Based on identified conclusions, particular implications for policy and practice to enhance PD to improve teaching quality were set at three levels: governmental, institutional, and individual. Moreover, achievements of the current study according to the research questions were identified and contributions of the study to the fields of PD, teaching quality, and the context of QA and quality audit in HE were addressed. Based on the findings and conclusions, particular directions and recommended issues were suggested to be studied by further research to benefit the enhancement of PD and related teaching quality improvement
Fullerene-like WS<sub>2</sub> supported Pd catalyst for hydrogen evolution reaction
No full textHydrogen is the most desirable green energy carrier and electrocatalytic hydrogen evolution reaction (HER) from water is a promising route for hydrogen production. The search for efficient, low-cost HER catalysts is a challenging and attracting topic. In this work, we report that inorganic fullerene-like WS2 supported Pd nanoparticles (Pd/WS2), with Pd loading of 0.76 wt%, are active for electrocatalytic HER conducted in 0.5 M H2SO4 solution, with overpotential at 10 mA cm−2 current density of ~130 mV and Tafel slope of 82.4 mV dec−1, which is comparable to that of Pt/WS2 (0.88 wt% Pt loading) with higher costs. Characteristic results indicate that WO3 impurities were in-situ produced on the WS2 surface and the Pd NPs are primarily located inside the WS2 nanocages. Contrasting experiments suggest that the WO3 impurities play a crucial role in generating Hads intermediate and the Pd NPs are active sites of H2 production, and a reaction mechanism is proposed. The Pd/WS2 catalyst also shows good long-term stability owing to the location of Pd NPs inside the WS2 cages. The high HER activity, low costs and good stability make the Pd catalyst a potential alternative to Pt catalyst for HER.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Micro and Nano Engineerin
Studies of clinically applicable human tolerogenic dendritic cells and PD-L2 genetic modification of human islet allograft to promote graft tolerance.
No full textIslet transplantation is a developing therapy for type 1 diabetic patients (T1D), which has been limited by problems associated with hypoxia, poor revascularisation and allograft rejection. Immunosuppressive agents used to prevent rejection are associated with severe side effects including islet toxicity, increased susceptibility to the development of cancer, infections and cardio-vascular problems. In order for islet transplantation to be used widely as a potentially curative treatment for T1D there is a need to develop novel therapies to treat allograft rejection without the use of immunosuppressive agents. In chapter 3, the immunomodulatory effects of IFN-γ on human monocyte-derived DC were investigated, using a standard 7-day in vitro DC propagation protocol. IFN-γ was shown to exert its immunomodulatory function on monocytes early during DC differentiation (IFNγ-DC[subscript]D0), resulting in an immature DC (iDC) phenotype with reduced expression of maturation markers CD83 and RelB. IFNγ-DC[subscript]D0 induced a state of T-cell hyporesponsiveness in a MLR, whilst IFN-γ treatment at day 5 (IFNγ-DC[subscript]D5) did not modulate DC function. The ability of IFN-γ to promote the generation of maturation arrested DC, could potentially serve as a cellular therapy for transplant rejection. However DC propagation using the standard 7-10 day protocol is not clinically applicable in the islet transplant setting. In chapter 4, a 'FAST-DC' protocol to promote the rapid generation of tolerogenic DC was investigated and used to generate IFNγ modulated DC in 48h. These IFNγ-DC featured an iDC phenotype similar to that seen in chapter 3. Maturation arrested IFNγ-DC caused significant T-cell hyporesponsiveness and promoted a higher frequency of CD4+CD25+ Foxp3[superscript]HI T-regulatory cells. IFNγ-DC primed T-cells were shown to be functionally suppressive in an antigen specific manner. It was also confirmed that IFN-γ reduced the phosphorylation of IL-4 activated STAT-6, which in turn affected the downstream gene expression of Interferon regulatory factor 4 (IRF4). IFNγ-DC were also investigated in vivo, where a humanised model of islet allo-transplantation model was developed. Diabetic NOD-SCID mice were transplanted with human islets and challenged with donor-derived DC and allogeneic PBMNC. After 21 days post transplantation, there was no significant change to euglycaemic state, between the tested groups. Genetic modification of the allograft is an alternative therapy to protecting the graft from the recipient‟s immune system. In chapter 5, human islets were genetically modified with programmed cell death ligand 2 (PD-L2), an inhibitory molecule known inhibit T-cell immune responses. Two recombinant adenovirus constructs carrying the PD-L2 gene were generated. One construct encoded a soluble isoform, while the other expressed a full transmembrane PD-L2 molecule. Adenoviral transduction did not affect the viability or insulin producing capacity of islets. Interestingly, soluble PD-L2 was more efficient at inducing signalling by 1000 fold, compared to the transmembrane isoform. In summary, this thesis demonstrated the timing of IFN-γ exposure is crucial in determining the function of DC and their maturational state, where IFN-γ exposure only during DC differentiation resulted in the inhibition of DC maturation. Secondly, the combination of IFN-γ and a FAST-DC protocol, enabled the generation of tolerogenic DC in 48h, making DC therapy more clinically applicable. Finally, the induced expression of soluble PD-L2 by human islets potently signals through human PD-1, which may provide the basis for the protection of islets from allo- and auto T-cell responses.Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 201
Enhanced T-Cell Immunity to Osteosarcoma Through Antibody Blockade of PD-1/PD-L1 Interactions
No full textabstract: Osteosarcoma is the most common bone cancer in children and adolescents. Although 70% of patients with localized disease are cured with chemotherapy and surgical resection, patients with metastatic osteosarcoma are typically refractory to treatment. Numerous lines of evidence suggest that cytotoxic T lymphocytes (CTLs) limit the development of metastatic osteosarcoma. We have investigated the role of PD-1, an inhibitory TNFR family protein expressed on CTLs, in limiting the efficacy of immune-mediated control of metastatic osteosarcoma. We show that human metastatic, but not primary, osteosarcoma tumors express a ligand for PD-1 (PD-L1) and that tumor-infiltrating CTLs express PD-1, suggesting this pathway may limit CTLs control of metastatic osteosarcoma in patients. PD-L1 is also expressed on the K7M2 osteosarcoma tumor cell line that establishes metastases in mice, and PD-1 is expressed on tumor-infiltrating CTLs during disease progression. Blockade of PD-1/PD-L1 interactions dramatically improves the function of osteosarcoma-reactive CTLs in vitro and in vivo, and results in decreased tumor burden and increased survival in the K7M2 mouse model of metastatic osteosarcoma. Our results suggest that blockade of PD-1/PD-L1 interactions in patients with metastatic osteosarcoma should be pursued as a therapeutic strategy.This is a non-final version of an article published in final form as Lussier, Danielle M., O'Neill, Lauren, Nieves, Lizbeth M., McAfee, Megan S., Holechek, Susan A., Collins, Andrea W., Dickman, Paul, Jacobsen, Jeffrey, Hingorani, Pooja, & Blattman, Joseph N. (2015). Enhanced T-Cell Immunity to Osteosarcoma Through Antibody Blockade of PD-1/PD-L1 Interactions. JOURNAL OF IMMUNOTHERAPY, 38(3), 96-106. http://dx.doi.org/10.1097/CJI.000000000000006
Modeling of Surface Segregation for Binary Alloys in Vacuum and Gas Environments: Applied to Pd-alloys
No full textComputational modeling offers the possibility to design alloys in a cheaper and faster way. A model for surface segregation for binary alloys in vacuum and by adsorption and absorption of gases was developed and applied. The proposed model was used in conjunction with the Miedema semi-empirical model for the calculation of enthalpies of solution and formation of binary alloys and with the cluster variation method (CVM) for the calculation of the ? and ? phase boundaries in the ternary Pd-M-H systems. The models for segregation were applied in a temperature range from 298K to 600K, considering the surface plane (111) of the FCC crystal structure. The model for segregation in vacuum was applied to Pd-Au, Pd-Ag, Pd-Cu, Pd-Ni and Pd-Pt. For this case Pd is segregated for the Pd-Pt alloys only. By increasing the temperature from 298K to 600K, the surface concentrations of Pd decreased for all of the alloys. By varying the plane from (111) to (100) few changes were observed. The calculated results compared to experiments were found to be in good agreement for Pd-Au and Pd-Ag. For the model of surface segregation by adsorption and chemisorption, H2, CO and O2 gases on Pd-Ag, Pd-Cu, Pd-Ni and Pd-Pt were considered. In the presence of adsorbed or chemisorbed hydrogen, segregation of Pd was found for Pd-Ag, Pd-Cu and Pd-Pt alloys. For adsorbed O2 and CO on Pd-Ag and Pd-Cu alloys gases, segregation of Pd was enhanced. The model for segregation by absorption of hydrogen was applied for Pd-Ag, Pd-Cu, Pd-Ni and Pd-Pt alloys, using a hydrogen (bulk) concentration of 0.50 H/M. No Pd segregation was found for Pd-Ag alloys. For Pd-Pt alloys, Pd segregation was observed. For Pd-Cu alloys with large concentrations of Pd, a surface enrichment of Pd was calculated, while for alloys with low concentration of Pd a slight Cu surface enrichment was observed. Enhanced segregation of Ni was found for Pd-Ni alloys. The H/M fractions at the boundaries of the ? and ? phase obtained with the CVM for the Pd85Ag15H system were used as input values to calculate the surface concentration of Ag. As the hydrogen concentration was increased, the surface segregation of Pd also increased. For the surface segregation by adsorption and absorption combined, segregation of Pd was observed for Pd-Ag, Pd-Cu and Pd-Pt alloys. Surface enrichment of Ni was found for Pd-Ni alloys. The proposed model enables to predict surface segregation under various conditions and the results show that it is affected by many parameters.Master Materials Science and EngineeringDepartment of Materials Science and EngineeringMechanical, Maritime and Materials Engineerin
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Novel fuzzy logic controllers with self-tuning capability
No full textTwo controllers which extend the PD+I fuzzy logic controller to deal with the plant having time varying nonlinear dynamics are proposed. The adaptation ability of the first self tuning PD+I fuzzy logic controller (STPD+I_31) is achieved by adjusting the output scaling factor automatically thereby contributing to significant improvement in performance. Second controller (STPD+I_9) is the simplified version of STPD+I_31 which is designed under the imposed constraint that allows only minimum number of rules in the rule bases. The proposed controllers are compared with two classical nonlinear controllers: the pole placement self tuning PID controller and sliding mode controller. All the controllers are applied to the two-links revolute robot for the tracking control. The tracking performance of STPD+I_31 and STPD+I_9 are much better than the pole placement self tuning PID controller during high speed motions while the performance are comparable at low and medium speed. In addition, STPD+I_31 and STPD+I_9 outperform sliding mode controller using same method of comparison study
APPLICATION OF SYNCHROTRON RADIATION TO HIGH PRESSURE X-RAY DIFFRACTION
No full textLa disponibilité de sources de radiation synchrotron à haute brillance est à l'origine de nombreux progrès dans les techniques de diffraction des rayons x. En plus des techniques de dispersion polychromatique d'énergie largement discutées, des progrès significatifs peuvent être accomplis grâce à l'utilisation de la radiation monochromatique lors d'un balayage angulaire ou de longueur d'onde. L'application de ces techniques développées à Daresbury, est esquissée pour des études à haute pression.The availability of dedicated, high brightness synchrotron radiation sources is leading to many improvements in x-ray diffraction techniques. In addition to the widely discussed polychromatic energy dispersive techniques, significant advances can be made by the use of monochromatic radiation in either angle- or wavelength-scanning. The application of these techniques, being developed at Daresbury, for high pressure investigations is outlined
Preparação e atividade catalítica de agregados nanoestruturados de metais nobres estabilizados por surfactantes dipolares iônicos baseados no anel imidazol
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.O presente trabalho descreve a aplicação de uma classe especial de surfactantes para a síntese de nanopartículas (NPs) metálicas anfifílicas em água ou micelas reversas. Os surfactantes utilizados são dipolares iônicos, com uma cadeia alquílica de 12 a 16 carbonos e um cabeça polar constituída de um grupo anel imidazólio e um grupo terminal propanosulfonato (ImS3-12, ImS3-14 e ImS3-16). Em solução aquosa, 3,3 surfactantes são necessários para proporcionar a estabilização. Os precursores metálicos empregados foram o K2PdCl4, AuCl3 and RhCl3 empregando-se 10 equivalentes de NaBH4 como agente redutor. As NPs de Pd foram preparadas utilizando-se os três surfactantes, e uma pequena variação no diâmetro de partícula (cerca de 3 nm) foi observada. As NPs de Rh e Au foram preparadas utilizando-se o surfactante ImS3-12, obtendo-se partículas de 1,8 e 5 nm, respectivamente. As NPs de Pd foram também preparadas em micelas reversas de ImS3-14 em CHCl3 utilizando-se ascorbato de sódio como agente redutor. Esse sistema permite o controle do tamanho de partícula pela mudança na quantia de água contida no interior das micelas reversas. As NPs foram caracterizadas por microscopia eletrônica de transmissão e difração de raios-x de pó, enquanto que as NPs de Pd preparadas com o ImS3-12 (Pd/12) foram ainda caracterizadas por espalhamento dinâmico de luz e análise termogravimétrica. Um modelo de estabilização em solução aquosa, que envolve a formação de uma bicamada de ImS3-12 sobre a partícula metálica, foi proposto. A atividade catalítica das NPs Pd/12 foi verificada através da hidrogenação bifásica do ciclohexeno em água, com fácil recuperação do catalisador e reciclo, com uma atividade catalítica duas vezes maior da obtida com o catalisador comercial Pd/C. As NPs Pd/12 foram quantitativamente adsorvidas em Al2O3 e carbono, obtendo-se um catalisador heterogêneo dez vezes mais ativo que o comercial Pd/C para a hidrogenação do ciclohexeno. Ainda, as NPs Pd/12 adsorvidas na Al2O3 foram utilizandas na redução parcial do biodiesel de soja. Nessa aplicação, o catalisador mostrou-se muito mais ativo do que o Pd/C, levando, na ausência de líquido iônico, ao biodiesel totalmente saturado. Na presença do LI BMIM.NTf2 a atividade catalítica do catalisador pôde ser controlada e a redução seletiva ao monoeno, com grande preferência pelo isômero cis, foi atingida a baixa temperatura, pressão e pouquíssimo catalisador, com lixiviação não detectável, além de excelente reciclabilidade. O biodiesel parcialmente hidrogenado mostrou-se muito mais estável à oxidação do que o biodiesel bruto, sem ocorrência de prejuízo às propriedades à frio do combustível.This work describes the application of a special class or surfactants for the synthesis of amphiphilic metal nanoparticles (NPs) in water or reversed micelles. The surfactants employed are zwitterionic, with an alkyl chain of 12, 14 and 16 carbon atoms and a polar head group constituted of a cationic imidazolium ring and a terminal anionic propane sulfonate group (ImS3-12, ImS3-14 e ImS3-16). In aqueous solutions, 3.3 surfactants per metallic atom are needed to afford good stabilization. The metallic precursors utilized were K2PdCl4, AuCl3 and RhCl3 which were reduced by addition of 10 equivalents of NaBH4. The Pd NPs were prepared using the three surfactants, and very small variation in particle diameter (about 3 nm) was observed. The Rh and Au NPs were prepared using ImS3-12, with a particle diameter of 1.8 nm and 5 nm, respectively. The Pd NPs were also prepared in reversed micelles in CHCl3 using ImS3-14 surfactant and sodium ascorbate as the reducing agent. The organic system allowed the control on particle size by changing the water content of the reversed micelles. The NPs were characterized by transmission electron microscopy and powder x-ray diffraction, while Pd NPs prepared in water using ImS3-12 (Pd/12) were further characterized by dynamic light scattering and thermogravimetric analy sis. A stabilization model, in aqueous solutions, involving the formation of a double layer of ImS3-12 around the metal surface was proposed. The catalytic activity of the Pd/12 was probed by biphasic hydrogenation of cyclohexene in water, with easy catalyst recycle and separation, with a catalytic activity twice that of commercial Pd/C catalyst. The Pd/12 could be quantitatively adsorbed on Al2O3 or carbon, giving a heterogeneous catalyst which was 10-fold more active than commercial Pd/C on cyclohexene hydrogenation. The Pd/12 NPs adsorbed on Al2O3 were also used for partial soybean biodiesel hydrogenation. In this application, the catalyst shows higher hydrogenation activity than conventional Pd/C, leading in the absence of ionic liquid (IL) to fully hydrogenated product. In the presence of BMIM.NTf2 IL the activity of the catalyst could be controlled and selective reduction to monoene product, with large preference for formation of the cis isomer, could be achieved at low temperature and pressure, with very low catalyst loading, no detectable metal leaching and good recyclability. The partially hydrogenated biodiesel is far more stable to oxidation than the crude, without compromising its cold-flow properties
Metrological Qualification of PD Analysers for Insulation Diagnosis of HVDC and HVAC Grids
No full textOn-site partial discharge (PD) measurements have turned out to be a very efficient technique for determining the insulation condition in high-voltage electrical grids (AIS, cable systems, GIS, HVDC converters, etc.); however, there is not any standardised procedure for determining the performances of PD measuring systems. In on-line and on-site PD measurements, high-frequency current transformers (HFCTs) are commonly used as sensors as they allow for monitoring over long distances in high-voltage installations. To ensure the required performances, a metrological qualification of the PD analysers by applying an evaluation procedure is necessary. A novel evaluation procedure was established to specify the quantities to be measured (electrical charge and PD repetition rate) and to describe the evaluation tests considering the measured influence parameters: noise, charge amplitude, pulse width and time interval between consecutive pulses. This procedure was applied to different types of PD analysers used for off-line measurements, sporadic on-line measurements and continuous PD monitoring. The procedure was validated in a round-robin test involving two metrological institutes (RISE from Sweden and FFII from Spain) and three universities (TUDelft from the Netherlands, TAU from Finland and UPM from Spain). With this round-robin test, the effectiveness of the proposed qualification procedure for discriminating between efficient and inappropriate PD analysers was demonstrated. Furthermore, it was shown that the PD charge quantity can be properly determined for on-line measurements and continuous monitoring by integrating the pulse signals acquired with HFCT sensors. In this case, these sensors must have a flat frequency spectrum in the range between several tens of kHz and at least two tens of MHz, where the frequency pulse content is more significant. The proposed qualification procedure can be useful for improving the future versions of the technical specification TS IEC 62478 and the standard IEC 60270.High Voltage Technology Grou
Surfactant-Induced Postsynthetic Modulation of Pd Nanoparticle Crystallinity
No full textModulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants. such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity cleciease significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylarnine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced, by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanncrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials
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