150 research outputs found

    Synthesis of b-substituted alanines via Michael addition of nucleophiles to dehydroalanine derivatives

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    Several b-substituted alanines are synthesised in high yields by a Michael addition of nucleophiles to N-acyl,N-tert-butyloxycarbonyl-dehydroalanine methyl ester, using mild reaction conditions and simple work-up procedures. The same method can be applied to dipeptides containing dehydroalanine

    High yielding synthesis of dehydroamino acid and dehydropeptide derivatives

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    By using a dimethylaminopyridine (DMAP) catalysed reaction of b-hydroxyamino acid derivatives with tert-butylpyrocarbonate [(Boc)2O], dehydroamino acid derivatives are obtained in high yields. The same methodology applied to dipeptides with a b-hydroxyamino acid residue gives the corresponding dipeptides with a dehydroamino acid residue

    Michael addition of thiols, carbon nucleophiles and amines to dehydroamino acid and dehydropeptide derivatives

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    Michael additions of nitrogen heterocycles, thiols, carbon nucleophiles and amines to dehydroalanine derivatives, including a glycyldehydroalanine peptide, were performed in fair to good yields. Dehydroaminobutyric acid derivatives reacted only with the stronger nucleophiles but in considerably lower yields and often no reaction was observed with the corresponding dehydrophenylalanine derivatives. When a tosyl group was bonded to the nitrogen atom of the dehydroamino acid, in some cases the addition product underwent elimination of this group and yielded the corresponding b-substituted derivative of the a,b-dehydroamino acid. Addition of some b- dicarbonyl compounds led to formation of products to which the structure of a,a-disubstituted cyclic amino acid derivatives was assigned

    A review on the laser-assisted flow deposition method: growth of ZnO micro and nanostructures

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    Zinc oxide (ZnO) is a widely versatile semiconductor with major importance from the technological point of view, presenting the advantage to be grown by a large number of techniques and with one of the richest varieties of morphologies. Due to the special interest of this semiconductor, several methods have been developed to control the production of its nanostructures. Herein, we report the development of a vapour-based method, designated by laser-assisted flow deposition (LAFD), able of producing ZnO micro and nanocrystals with different morphologies, with a high crystalline and optical quality. This new process allows high yield of ZnO production, showing great prospects for scalable applications. In the present work, we review in detail the main growth parameters and their relationship with the produced morphologies, in addition to their influence in the structural and optical properties. Furthermore, an assessment of the possible growth mechanisms that may be involved in this new method is reported. Some potential applications of the ZnO structures produced by LAFD were also evaluated, with focus on the photocatalysis and photovoltaic fields. Additionally, the possibility of synthesizing ZnO composite nanostructures, as well as the growth of other metal oxides using this technique was explored.publishe

    Corrigendum: "To be or not to be Retained… That's the Question!" Retention, Self-esteem, Self-concept, Achievement Goals and Grades

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    [This corrects the article on p. 1550 in vol. 7, doi:10.3389/fpsyg.2016.01550, PMID: 27790167.]. Also available at: http://hdl.handle.net/1822/44636There is an error in the Funding statement. The statement should be “This study was supported by the FCT - Fundação para a Ciência e a Tecnologia through the research project PTDC/CPE-CED/121358/2010 and UID/CED/04853/2016.” The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way.There is an error in the Funding statement. The statement should be "This study was supported by the FCT - Fundacao para a Ciencia e a Tecnologia through the research project PTDC/CPE-CED/121358/2010 and UID/CED/04853/2016.

    Patient-centeredness: contribution to the adaptation of the Patient-Practitioner Orientation Scale (PPOS)

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    Objetivo: Este estudo teve como objetivo traduzir e contribuir para a adaptação para a população portuguesa (Português Europeu) da Patient-Practitioner Orientation Scale (PPOS). Método: Após o processo de tradução e de pré-teste, a escala foi aplicada a 593 estudantes do 1º ao 6º ano do curso de Medicina em várias Universidades de Portugal Continental. A validade do construto e a fiabilidade do instrumento foram aferidas através da análise fatorial exploratória (ACP) e confirmatória (AFC), e do cálculo do coeficiente alpha de Cronbach. Resultados: A versão final explica 31.54% da variância total e confirma a estrutura em dois fatores: Caring, (19.56% da variância) e Sharing (11.98% da variância). Os itens 2 e 4 apresentaram inconsistências com os fatores definidos à priori (versão original do instrumento), os itens 9 e 17 obtiveram cargas fatoriais inferiores a .3, e o item 3 registou uma diferença inferior a .1 entre as cargas fatoriais para os dois domínios. Os coeficientes de alpha de Cronbach foram .65, .50 e .56 para a escala total, e subscalas Caring e Sharing, respetivamente. A AFC revelou um bom ajustamento global do modelo de medida (χ2(132, N = 593) = 344.28, p < .001; χ2/gl = 2.61; GFI = .93; AGFI = .92; CFI = .87; NNFI = .81; SRMR = .084; RMSEA = .05, 95% CI [0.045, 0.059], p = .293). As análises exploratórias posteriores sugerem a possibilidade de melhoria dos índices de validade e de fiabilidade da escala total e da sub-escala Caring, com a retirada de itens específicos. Conclusão: Não obstante as fragilidades encontradas no que concerne à fiabilidade e validade da PPOS-P para uma amostra de estudantes portugueses de Medicina, este estudo representa um contributo científico para a adaptação da escala, que pode ser considerada para efeitos de avaliação de atitudes de centração no paciente nos contextos da educação médica e da investigação.ABSTRACT - Objective: The purpose of this study was to contribute to the European Portuguese adaptation of the Patient-Practitioner Orientation Scale (PPOS). Method: A sample of 593 medical students participated in the study. After permission from the original author, the translation procedures required to ensure translation of the PPOS to European Portuguese were performed. Construct validity (exploratory and confirmatory factor analysis) and reliability (internal consistency) were assessed. Results: The final version confirmed the original structures of two factors, explaining 31.54% of total variance; Caring (19.56%) and Sharing (11.98%). Items 2 and 4 showed inconsistencies with the factors defined earlier in the original version of the instrument, items 9 and 17 obtained a factorial load less than .3, and the item 3 achieved a difference of less than .1 between factorial charges for the two domains. The internal consistency of PPOS-P scales was adequate (Cronbach’s alpha of .65, .50 and .56 for total scale, and subscales Caring and Sharing, respectively). Confirmatory factor analysis provided an acceptable adjustment for the observed variables (χ2(132, N = 593) = 344.28, p < .001; χ2/gl = 2.61; GFI = .93; AGFI = .92; CFI = .87; NNFI = .81; SRMR = .084; RMSEA = .05, 95% CI [0.045, 0.059], p = .293). Subsequent exploratory analyzes suggest the potential for improving the levels of validity and reliability of the total scale and Caring subscale, with the removal of specific items. Conclusion: Although the fragilities identified in the validity and reliability of the PPOS-P in a sample of Portuguese medical students, this work can represent an important and useful contribution to further investigations that might consider this instrument as a measure of student’s changes of patient-centeredness attitudes.info:eu-repo/semantics/publishedVersio

    Clarifying changes in student empathy throughout medical school: a scoping review

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    Despite the increasing awareness of the relevance of empathy in patient care, some findings suggest that medical schools may be contributing to the deterioration of students' empathy. Therefore, it is important to clarify the magnitude and direction of changes in empathy during medical school. We employed a scoping review to elucidate trends in students' empathy changes/differences throughout medical school and examine potential bias associated with research design. The literature published in English, Spanish, Portuguese and French from 2009 to 2016 was searched. Two-hundred and nine potentially relevant citations were identified. Twenty articles met the inclusion criteria. Effect sizes of empathy scores variations were calculated to assess the practical significance of results. Our results demonstrate that scoped studies differed considerably in their design, measures used, sample sizes and results. Most studies (12 out of 20 studies) reported either positive or non-statistically significant changes/differences in empathy regardless of the measure used. The predominant trend in cross-sectional studies (ten out of 13 studies) was of significantly higher empathy scores in later years or of similar empathy scores across years, while most longitudinal studies presented either mixed-results or empathy declines. There was not a generalized international trend in changes in students' empathy throughout medical school. Although statistically significant changes/differences were detected in 13 out of 20 studies, the calculated effect sizes were small in all but two studies, suggesting little practical significance. At the present moment, the literature does not offer clear conclusions relative to changes in student empathy throughout medical school.info:eu-repo/semantics/publishedVersio

    Optical Studies in Red/NIR Persistent Luminescent Cr‐Doped Zinc Gallogermanate (ZGGO:Cr)

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    Zn1+xGa2‐2xGexO4 (ZGGO:Cr)‐persistent phosphor, with a molar fraction, x, of x = 0.1, doped with a 0.5% molar of chromium, was synthesised via solid‐state reaction at 1350 °C for 36 h. X‐ray diffraction measurements and Raman spectroscopy evidence a single crystalline phase corresponding to the cubic spinel structure. Room temperature (RT) photoluminescence (PL) and afterglow decay profiles were investigated using above and below bandgap excitation. In both cases, persistent PL was observed for almost 8 h, mainly originating from a Cr3+ defect, the so‐called N2 optical centre. RT PL excitation and diffuse reflectance allow identification of the best pathways of Cr3+ red/NIR emission, as well as estimation of the ZGGO bandgap energy at 4.82 eV. An in‐depth investigation of the observed luminescence at 15 K and temperature‐dependent PL under site‐selective excitation reveals the spectral complexity of the presence of several optically active Cr3+ centres in the ZGGO host that emit in almost the same spectral region. Furthermore, the temperature dependence of the R‐lines’ intensity indicates the existence of thermal populating processes between the different optical centres. Such observations well account for a wide distribution of defect trap levels available for carrier capture/release, as measured by the persistent luminescence decay, from which the carriers are released preferentially to the N2 Cr3+‐related optical centre.publishersversionpublishe

    Trends in legal and illegal trade of wild birds: a global assessment based on expert knowledge

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    Wildlife trade is a profitable economic activity. Birds are among the most heavily traded animals worldwide, with numerous species threatened by pet trade. Information on both legal and illegal aspects of trade and consumer demand is difficult to obtain across different countries, particularly given substantial socio-economic and cultural variation. Focusing on consumer demand in each country, we conducted a global survey among 105 international experts on bird conservation to identify expected trends, drivers and market characteristics of legal and illegal wild-caught pet bird trade. Our results suggest that future trends in legal bird trade will be mostly driven by socio-cultural motivations and intentional demand for wild-caught, rather than captive-bred birds. Bird popularity and rarity are the main factors expected to influence the choice of which bird species will be the most traded legally. Percentage of rural population was the main national-level socio-economic predictor for legal bird trade in the future. Demand for future illegal trade is expected to be driven by bird popularity and particular species identity. Experts consider illegal trade to be sustained mainly by consumers from higher socio-economic and educational backgrounds. Human population growth rate was the main national-level socio-economic predictor of illegal trade expected for the future. Legislation enforcement remains a critical issue in wildlife trade. Expanding trade networks and socio-economic changes continue to incorporate new regions into the wildlife trade. Investigating the multidimensional and synergistic determinants of wildlife trade will thus help address potential detrimental impacts bird trade might cause on biodiversity.This research was funded by FEDER Funds through the Operational Competitiveness Factors Program “COMPETE”, and by national funds through the Foundation for Science and Technology (FCT) within the framework of project “PTDC/AAG-GLO/0463/2014-POCI-01-0145-FEDER-016583”. A.N. acknowledges the support of the Darwin Initiative. J.R. acknowledges the support from FCT through Grant ICETA 2017-38 within project “PTDC/AAG-GLO/0463/2014-POCI-01-0145-FEDER-016583”. L.R. and C.C. acknowledge support from the FCT through Grants SFRH/BPD/93079/2013 and SFRH/BPD/84422/2012, respectively
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