11,797 research outputs found
The CTLA-4 and PD-1/PD-L1 inhibitory pathways independently regulate host resistance to Plasmodium-induced acute immune pathology.
No full textThe balance between pro-inflammatory and regulatory immune responses in determining optimal T cell activation is vital for the successful resolution of microbial infections. This balance is maintained in part by the negative regulators of T cell activation, CTLA-4 and PD-1/PD-L, which dampen effector responses during chronic infections. However, their role in acute infections, such as malaria, remains less clear. In this study, we determined the contribution of CTLA-4 and PD-1/PD-L to the regulation of T cell responses during Plasmodium berghei ANKA (PbA)-induced experimental cerebral malaria (ECM) in susceptible (C57BL/6) and resistant (BALB/c) mice. We found that the expression of CTLA-4 and PD-1 on T cells correlates with the extent of pro-inflammatory responses induced during PbA infection, being higher in C57BL/6 than in BALB/c mice. Thus, ECM develops despite high levels of expression of these inhibitory receptors. However, antibody-mediated blockade of either the CTLA-4 or PD-1/PD-L1, but not the PD-1/PD-L2, pathways during PbA-infection in ECM-resistant BALB/c mice resulted in higher levels of T cell activation, enhanced IFN-γ production, increased intravascular arrest of both parasitised erythrocytes and CD8(+) T cells to the brain, and augmented incidence of ECM. Thus, in ECM-resistant BALB/c mice, CTLA-4 and PD-1/PD-L1 represent essential, independent and non-redundant pathways for maintaining T cell homeostasis during a virulent malaria infection. Moreover, neutralisation of IFN-γ or depletion of CD8(+) T cells during PbA infection was shown to reverse the pathologic effects of regulatory pathway blockade, highlighting that the aetiology of ECM in the BALB/c mice is similar to that in C57BL/6 mice. In summary, our results underscore the differential and complex regulation that governs immune responses to malaria parasites
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
Obtenção, caracterização e avaliação da atividade de um nanocatalisador de Pd(0) sintetizado in situ sob a superfície de Fe3O4@dextrana para redução do 4-nitrofenol
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2015.O objetivo principal deste trabalho é a preparação, caracterização e avaliação da atividade catalítica das nanopartículas (NPs) de Pd impregnadas no suporte magnético magnetita e estabilizada por dextrana. As NPs-Pd foram preparadas por crescimento in situ sob a superfície de nanopartículas superparamagnéticas (NPSMs) (Fe3O4@dextrana/Pd(0)). O controle do crescimento das NPs-Pd foi feito com o auxílio de NaBH4, como agente redutor. O catalisador de Fe3O4@dextrana/Pd foi totalmente caracterizado por diversas técnicas tais como espectroscopia de infravermelho, espalhamento de luz dinâmico, espalhamento de raios-X a baixos ângulos, microscopia eletrônica de transmissão e varredura, e difração de raios-X de pó. A caracterização mostrou que o catalisador é constituído de um suporte feito de Fe3O4@dextrana composto por unidades de nanocristais com tamanho de 9,7 nm, formando nanoclusters de 105,6 nm, contendo as NPs-Pd de 7,8 nm impregnadas em sua superfície. Os estudos cinéticos foram realizados por UV-vis, sendo que a atividade catalítica foi avaliada pela reação modelo de redução do p-nitrofenol (Nip), utilizando NaBH4. Aplicando um modelo de reação de superfície pseudo-molecular, a reação foi investigada pelo modelo teórico de isoterma de adsorção, revelando ser uma reação bimolecular que segue o mecanismo de Langmuir-Hinshelwood. A atividade catalítica do nanocatalisador Fe3O4@ dextrana/Pd com área superficial de 3,33 m2L-1x10-3 (0, 0053 mg L-1 de Pd) pode ser efetivamente analisada, e foi possível obter os parâmetros cinéticos kL, KBH4- e KNip. Os resultados mostraram que as moléculas de Nip possuem afinidade de adsorção muito maior do que BH4- pela superfície das NPs-Pd, resultado da influência do caráter hidrofóbico do Nip sob a constante de adsorção do substrato. Um novo parâmetro de atividade catalítica ??? foi proposto e utilizado com sucesso na comparação com outros catalisadores reportados na literatura. As NPSMs de Fe3O4@dextrana/Pd apresentaram um valor de ? = 3,65 L mg-1 s-1, superior ao citado na literatura. O estudo do reuso de Fe3O4@dextrana/Pd demonstrou que é possível reutilizar as mesmas por até 5 vezes com cerca de 99% de conversão do Nip e valor alto de TOF, 692 h-1.Abstract : The aim of this work was the preparation, characterization and evaluation of catalytic activity of Pd nanoparticles (NPs) impregnated in magnetite and stabilized by dextran. The Pd NPs were prepared by the in situ growth under the surface of superparamagnetic nanoparticles. The growth control of Pd NPs was made with the aid of NaBH4, as reducing agent. The catalyst Fe3O4@dextran/Pd was fully characterized by several techniques such as: infrared spectroscopy, dynamic light scattering, X-ray scattering at small angle, transmission and scanning electron microscopy , and diffraction X-ray powder. The characterization revealed that the catalyst consisted of a support made of Fe3O4@dextran nanocrystals composed of units with 9.7 nm in size, forming nanoclusters of 105.6 nm containing NPs of Pd with 7.8 nm diameter, impregnated in the surface. The kinetic studies were performed by UV-vis spectrocopy, and the catalytic activity was evaluated by the model reaction of the p-nitrophenol (Nip) reduction, using NaBH4 as a reducing agent. Applying a pseudo-molecular surface reaction approach, the reduction reaction could be investigated by means of a theoretical adsorption model, revealing that the reaction is bimolecular and followed the Langmuir-Hinshelwood mechanism.The catalytic activity of nano-catalyst of Fe3O4@dextran/Pd, with a surface area of 3.33m2L-1x103 (0.0053 mg L-1Pd), could be effectively determined, obtaining the kinetic parameters kL, KBH4- and KNip. These kinetics results showed that the Nip molecules have higheraffinity for the catalyst surface than the molecules of BH4-, as a result of the influence of the Nip hydrophobic character. A new catalytic activity parameter "?" was proposed and effectively used for comparison with other recent reported catalysts. The reuse studies showed that could be reused up to 5 times with about 99% conversion of Nip and a high TOF value, 692 h-1
Unveiling Parkinson’s: Empowering Our Community Through Awareness
No full textAwareness about situations or conditions has brought many changes to public policy, treatment methods, and community engagement, to name just a few. Awareness also creates a culture of “seeing” people who may feel unseen or dismissed. One particular group that may feel this way are people with Parkinson’s disease. Parkinson’s disease (PD) is a progressive neurodegenerative disorder primarily resulting from a decrease in dopamine levels. This decrease in dopamine can lead to deficiencies in motor control and cognitive function that can include slow and uncoordinated movement, loss of balance, loss of smell, and decreased cognitive function1. The implementation of a community awareness event can serve to educate and inform community influencers about this population. In 2022 the first “Walk a Mile in my (Parkinson’s) Shoes” event was established. The goal of the event was and is to create awareness, understanding and empathy for those who have PD. Influential individuals within the surrounding community are invited to spend the morning experiencing what it means to Walk a mile in my (Parkinson’s) shoes. This experience involves being given the opportunity to learn about PD and participate in a variety of activities that simulate living with PD. The purpose of this presentation will be to elaborate on how and why this event was established, discuss some of the outcomes from the 2023 event, and hopefully inspire the audience to unveil the groups in our community that need to be seen
Pd-promoted WO3-ZrO2 for low temperature NOx storage
No full textPd-promoted ZrO2 and WO3-ZrO2 (W-Zr) were investigated for low temperature NOx adsorption and release. Pd-promoted W-Zr exhibited high NOx storage efficiency at short storage times, subsequently releasing ∼95% of the stored NOx upon thermal ramping to 350 °C. DRIFTS studies demonstrated that Pd increased nitrate formation relative to nitrite during NOx storage on both Pd-Zr and Pd-W-Zr. Moreover, Pd sites on Pd-W-Zr played a major role in NOx storage, the ad-species being readily removed by 350 °C. From NO- and CO-DRIFTS data, it is inferred that Pd on the acidic W-Zr support was present as mainly cationic species, and was therefore able to adsorb NO, whereas on ZrO2 Pd was not able to directly store NOx. Co-feeding CO with NO resulted in increased NOx storage capacity for Pd-W-Zr, which on the basis of DRIFTS measurements is attributed to the formation of Pd2+(CO)(NO) complexes
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
Selective lignin depolymerization via transfer hydrogenolysis using Pd/hydrotalcite catalysts: model compounds to whole biomass
No full textCleavage of lignin ether bonds via transfer hydrogenolysis is a promising route to valorize lignin, thus processes that use mild reaction conditions and exploit renewable hydrogen donor solvents (rather than molecular hydrogen) are economically advantageous. Herein we demonstrate the efficient catalytic transfer hydrogenolysis and tandem decarbonylation of lignin model compounds possessing aromatic ether bonds (α-O-4, β-O-4 and 4-O-5 linkages), over transition metal-modified Pd hydrotalcite catalysts with ethanol as the hydrogen donor and solvent. Quantitative conversions and yields were attained for all model compounds, except for 4-O-5 models, which possess inherently strong sp2 C-O bonds. The latter demonstrates the utility of Pd hydrotalcite catalysts for transfer hydrogenolysis of model compounds. This process was employed to achieve whole pine biomass delignification with 97% yield and a 22% phenolic monomer yield, with 64% selectivity for 4-(3-hydroxypropyl)-2-methoxyphenol.Full Tex
Acceptance and commitment therapy: cognitive fusion and personality functioning
No full textPersonality disorders (PDs) are common, chronic, mental health problems. The majority of treatment outcome research, which has focused specifically on Borderline PD, has provided substantial empirical support for Dialectical Behaviour Therapy (DBT; Linehan, 1993), particularly in terms of self-harm reduction. Nevertheless, DBT graduates can continue to experience poor personality functioning across PD diagnostic categories, Axis I disorders, and restricted lives. Acceptance and Commitment Therapy (ACT; Hayes, Strosahl, & Wilson, 1999), might be suitable as a follow-up intervention for DBT graduates, to address their continued difficulties: to date, however, there has been little empirical investigation of its utility in relation to PD. This thesis was therefore designed to examine theoretical underpinnings of ACT relevant to the development of an ACT intervention for DBT graduates.Study 1 tested the performance of a new self-report measure of cognitive fusion (CF), the Cognitive Fusion Questionnaire (CFQ), with a mental health sample, including individuals with PD. CF is a key ACT concept, and the CFQ proved to be a psychometrically sound measure of CF with people with mental health problems. Study 2 used cross-sectional modelling to show that CF fully mediated the relationships between two PD risk factors, negative affectivity and childhood trauma, and personality functioning in adulthood. Study 3 used the CFQ to investigate the behavioural correlates of CF. These findings strengthened the possibility that an ACT-based intervention might prove effective in improving outcomes for DBT graduates. To explore this further, Studies 4 and 5 were designed as very small-scale uncontrolled treatment development trials for this population. Study 4 suggested that ACT had a positive impact on engagement in life, but produced little improvement in psychiatric symptomology. Study 5 tested a revised protocol, which yielded more consistently positive findings, with improvements in both engagement in life and psychiatric symptoms. These findings tentatively suggest that ACT may have a role to play as a DBT follow-up intervention
A RAIRS, TPD and femtosecond laser-induced desorption study of CO, NO and coadsorbed CO + NO on Pd(111)
No full textHere we present a systematic study of the adsorption and laser induced desorption of CO, NO and CO + NO from a Pd(111) surface at a number of different coverages. We begin by characterising the surfaces using reflection-absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD). Experiments show that NO displaces pre-adsorbed CO considerably, but that CO has a much smaller effect on pre-adsorbed NO. In both cases, the preferred binding sites of CO are occupied by NO, displacing it to less favourable adsorption sites. Femtosecond laser induced desorption (fs-LID) shows that desorption of CO on Pd(111) follows a power law and is fairly independent of CO coverage, but for NO on Pd(111) we observe a clear deviation from a power law curve at higher coverages, with saturation being observed. This suggests that the cross-section for LID of NO is much larger than that for CO and that NO on Pd(111) is more photoactive than CO on Pd(111). Interestingly, for CO + NO on Pd(111) we find that coadsorption has a strong influence on the photodesorption process and that the structure of the overlayer is also important in controlling the photodesorption products, regardless of the order in which the two molecules are dose
Highly selective Pd/titanate nanotube catalysts for the double-bond migration reaction
No full textPd(II) and Pd(0) catalysts supported onto titanate nanotubes (H2Ti3O7) were prepared by an ion-exchange technique. The catalysts are characterised by narrow size distribution of metal nanoparticles on the external surface of the nanotubes. Pd(II) catalysts show high selectivity toward double-bond migration reaction versus hydrogenation in linear olefins. The catalytic activity exhibits a volcano-type dependence on the metal loading, with the maximum activity observed at ca. 8 wt%. The Pd(II) was shown to be rapidly reduced to Pd(0) by appropriate choice of solvent. Prereduced Pd(0) catalysts were found to be less active toward double-bond migration and more selective toward hydrogenation. The DBM reaction was faster in protic solvents, such as methanol or ethanol
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