The Conductance and Thermopower Behavior of Pendent Trans-Coordinated Palladium(II) Complexes in Single-Molecule Junctions

The present work provides insight into the effect of connectivity within isomeric 1,2-bis(2-pyridylethynyl)benzene (bpb) palladium complexes on their electron transmission properties within gold|single-molecule|gold junctions. The ligands 2,2′-((4,5-bis(hexyloxy)-1,2-phenylene)bis(ethyne-2,1-diyl))bis(4-(methylthio)pyridine) (Lm) and 6,6′-((4,5-bis(hexyloxy)-1,2-phenylene)bis(ethyne-2,1-diyl))bis(3-(methylthio)pyridine) (Lp) were synthesized and coordinated with PdCl2 to give the trans-Pd(Lm or p)Cl2 complexes. X-ray photoelectron spectroscopy (XPS) measurements shed light on the contacting modes of the molecules in the junctions. A combination of scanning tunneling microscopy–break junction (STM–BJ) measurements and density functional theory (DFT) calculations demonstrate that the typical lower conductance of meta- compared with para-connected isomers in a molecular junction was suppressed upon metal coordination. Simultaneously there was a modest increase in both conductance and Seebeck coefficient due to the contraction of the HOMO–LUMO gap upon metal coordination. It is shown that the low Seebeck coefficient is primarily a consequence of how the resonances shift relative to the Fermi energy

Prospective and retrospective memory complaints in mild cognitive impairment and mild Alzheimer’s disease

Current management attempts for Alzheimer’s disease (AD) focus on the identification of individuals in the preclinical stage. This has led to the development of the diagnostic concept of Mild Cognitive Impairment (MCI), which applies to individuals with declining cognitive abilities but largely preserved everyday functioning. Previous findings indicate that prospective memory deficits are a sensitive marker of preclinical AD and that awareness of prospective memory failures is particularly high, based on its dependence on executive functions. Thus, the goal of this study was to evaluate the usefulness of subjective prospective versus retrospective memory complaints for an initial screening for MCI and their respective associations with executive functions. 71 healthy older adults, 27 MCI patients, and 9 patients with mild AD completed the Prospective and Retrospective Memory Questionnaire (PRMQ) and three executive functions tests. The healthy and the MCI group could not be distinguished by their level of subjective prospective or retrospective memory complaints, but the mild AD patients differed from the other groups by complaining more about retrospective than prospective memory failures. For the healthy older adults, the prospective memory complaints were correlated to an inhibition test, whereas they did not correlate with any of the executive function tests in the MCI patients. In contrast, in both groups the retrospective memory complaints were related to a task switching test. The findings are discussed with respect to differences between the three groups in cognitive abilities, attention to failures of, use of mnemonic aids for, and everyday demands of prospective and retrospective memory

Desempenho de idosos em uma tarefa motora de demanda dupla de controle Aging motor performance in a dual task control

A literatura sobre o processo de envelhecimento tem sistematicamente demonstrado a diferença de desempenho entre populações jovens e idosas. Em geral, os delineamentos de pesquisa envolvem indivíduos de 60 e até mesmo de 90 anos de idade, enquanto o grupo de jovens é representado por indivíduos em torno de 20 anos de idade. Esse procedimento pode ocultar mudanças de desenvolvimento que talvez influencie a interpretação dos resultados. Assim, o objetivo desse estudo foi examinar o efeito da idade cronológica no desempenho de uma habilidade motora. Foi utilizado um aparelho que possibilitou a execução de uma tarefa de posicionamento linear combinada ao controle de força. Os participantes receberam conhecimento de resultados verbal após a execução de 10 tentativas sobre o objetivo de atingir 20% da força máxima e o deslocamento de 35 cm. O desempenho foi medido pelo erro absoluto. A amostra contou com 150 participantes de 60 a 86 anos de idade, que realizaram as tentativas com a mão não-dominante e vendados. Os participantes foram divididos em três grupos etários (60, 70, 80 anos) e o desempenho também foi comparado a um grupo jovem (21 a 30 anos de idade). Houve correlação baixa, mas significante entre idade e controle de distância. Não houve diferença significante entre os grupos (exceto G20 e G80). Apesar da observação empírica dos instrutores sobre a diferença no desempenho motor de idosos de diferentes faixas etárias, o presente estudo não mostrou tais diferenças no desempenho dessa tarefa em particular. Talvez, considerando que os participantes eram fisicamente ativos, possíveis diferenças de desempenho relativas ao processo de envelhecimento, possam ter sido sobrepostas pelo estilo de vida ativo.<br>Motor behavior literature about aging process has systematically shown differences in performance between young and old populations. Experimental designs involve groups of old, ranging from 60 to even over 90 years old, while groups of young people are usually represented by participants in their early 20's. Such procedure could hide developmental changes with the advance of age and, consequently, could lead to results misinterpretation. Therefore the main purpose of this study was to verify whether there is an age effect on the performance in a motor task. It was used an apparatus enabling a linear positioning combined with a manual force control task. Participants performed the motor task receiving verbal knowledge of result in ten trials about the immediately finished trial that provided information about accomplishing the goal of 20% of the maximum force and 35cm of displacement. Performance was measured by absolute errors. The sample comprised 150 participants raging from 60 to 86 years old, which performed the task blinded folded and with non-dominant hand. Participants were divided in three age groups (60, 70, 80 years), and performance was also compared with a young group (21 to 30 years old). Correlation analyses show a significant but low age effect in distance control, and there was no difference in performance among older groups (except G20 and G80). Despite instructor's empirical observation about differences in motor performance with aging, apart from fitness, surprisingly, the present study did not show such age effect on the performance of this particular motor task. Perhaps, considering that these participants were physically active, possible differences in motor performance due to development were overcome by their lifestyle