242 research outputs found
Novel synthetic approach to heteroatom doped polycyclic aromatic hydrocarbons: Optimizing the bottom-up approach to atomically precise doped nanographenes
The success of the rational bottom-up approach to nanostructured carbon materials and the discovery of the importance of their doping with heteroatoms puts under the spotlight all synthetic organic approaches to polycyclic aromatic hydrocarbons. The construction of atomically precise heteroatom doped nanographenes has evidenced the importance of controlling its geometry and the position of the doping heteroatoms, since these parameters influence their chemical–physical properties and their applications. The growing interest towards this research topic is testified by the large number of works published in this area, which have transformed a once “fundamental research” into applied research at the cutting edge of technology. This review analyzes the most recent synthetic approaches to this class of compounds
Unravelling the ultrafast dynamics of a N-BODIPY compound
Although the photophysics of BODIPY compounds has been widely investigated in the last few years, their analogues N-BODIPY, with nitrogen substitution at the boron center, did not receive comparable attention. In this work we report the synthesis and photochemical characterization of a substituted N-BODIPY compound, by means of a combined theoretical and spectroscopic approach. Compared to a standard BODIPY, the compound under investigation presents a lower fluorescence quantum yield (QY) in the visible region. The excited state relaxation dynamics of the dye was studied in different solvents, showing further fluorescence quenching in polar solvents, and excited state decay rates strongly dependent on the environment polarity. The role of the pendant moieties and the involvement of charge transfer states in the excited state dynamics was experimentally addressed by transient absorption spectroscopy, and further analyzed with TD-DFT calculations, which allowed precise assignment of the transient signals to the correspondent electronic configuration. The complete picture of the N-BODIPY behavior shows the presence of both charge transfer and localized states, influencing the observed photophysics to different amounts, depending on the excitation conditions and the surrounding environment
Second-harmonic generation sensitivity to transmembrane potential in normal and tumor cells.
Second-harmonic generation (SHG) is emerging as a powerful tool for the optical measurement of transmembrane potential in live cells with high sensitivity and temporal resolution. Using a patch clamp, we characterize the sensitivity of the SHG signal to transmembrane potential for the RH 237 dye in various normal and tumor cell types. SHG sensitivity shows a significant dependence on the type of cell, ranging from 10 to 17% per 100 mV. Furthermore, in the samples studied, tumor cell lines display a higher sensitivity compared to normal cells. In particular, the SHG sensitivity increases in the cell line Balb/c3T3 by the transformation induced with SV40 infection of the cells. We also demonstrate that fluorescent labeling of the membrane with RH 237 at the concentration used for SHG measurements does not induce any measurable alteration in the electrophysiological properties of the cells investigated. Therefore, SHG is suitable for the investigation of outstanding questions in electrophysiology and neurobiology
Proteomics-based investigation in C2C12 myoblast differentiation
Skeletal muscle cell differentiation is a multistage process extensively studied over the years. Even if great improvements have been achieved in defining biological process underlying myogenesis, many molecular mechanisms need still to be clarified
Fatores ambientais sobre pesos em diferentes idades de ovinos da raça Santa Inês no Nordeste do Brasil.
Com o objetivo de avaliar os efeitos de ambiente sobre as características de crescimento dos cordeiros, foram analisados registros de 4094 cordeiros da raça Santa Inês provenientes de rebanhos dos estados da Paraíba, Ceará e Sergipe, coletados num período de 23 anos (1983 a 2005). Foram avaliados os efeitos da estação, do ano de nascimento, sexo do cordeiro, tipo de nascimento e idade da mãe ao parto sobre os pesos corporais ao nascimento (PN), aos 56 dias de idade (P56), aos 112 dias de idade (P112) e aos 196 dias de idade (P196). Os cordeiros nascidos na estação chuvosa e seca não apresentaram diferenças significativas para PN, P56 e P112, porém no P196 os animais nascidos em estação chuvosa apresentaram pesos maiores. Os cordeiros machos foram mais pesados que as fêmeas em todas as idades estudadas. Cordeiros nascidos de parto simples pesaram mais que os nascidos de parto duplo, entretanto, houve interação significativa entre sexo e tipo de parto em que foi observado que fêmeas nascidas de parto simples tiveram pesos maiores que os machos de parto duplo em todas as idades avaliadas. Desta forma, torna-se evidente a necessidade de inclusão e ajuste destas características, como ferramentas de auxílio na avaliação genética e seleção dos animais visando melhoria no desempenho de ovinos da raça Santa Inês. Environmental factors on weights of different ages of Santa Inês sheep in the Northeasterner of Brazil. Abstract: The aim of this study was to evaluate environmental effects on growth performance in Santa Inês lambs, were using data of 4.094 lambs proceeding from Paraíba, Ceará and Sergipe states, collected over an 23-year period (1983 to 2005). The environmental effects of season of birth (winter or summer), sex of lamb, age of dam at lambing and type of birth (single or twins), were important sources of variation to explain differences in weigth at birth (WB), at 56 (W56), 112 (W112) and 196 (W196) days of age. The lambs born in the rain and dry no observed significant differences for WB,WP112 and W56, but the W196 animals born in the rainr season showed higher weights. Males were heavier than female lambs at all ages. Lambs born as singles were heavier (P < 0.01) than lambs born as twins at all ages, however, there was significant interaction between sex and type of birth, that was observed that females lambs born as single had larger weights than the males of twins in all ages. Adjustment factors for sex of lamb, type of birth and age of ewe at lambing need to be estimated and considered in selection programs to improve growth trait of Santa Inês
Acoustic correction factor estimate for compensating vertical diel migration of small pelagics
Differences in acoustic estimates of small pelagic fish biomass, due to data acquisition during daytime and nighttime surveys, have been recognized for many years as a problem in acoustic surveys. In the absence of a single rule for all species and for all locations, some expert groups identified specific time intervals for acoustic data acquisition in relation to the schooling behavior of the target species. In the Mediterranean Sea, the research groups working in the MEDIAS (Mediterranean International Acoustic Survey) agreed on the importance that acoustic sampling are conducted only during day-time. Only when available time does not permit to complete the survey during daytime, data collection might be extended. In this case, working on data collected during both daytime and nighttime, a bias may occur in the biomass estimates. In order to evaluate and correct such bias, specific experiments were performed in some geographical sub-areas of the Mediterranean Sea. The data analysis allowed the estimation of a mean correction factor for the Strait of Sicily, where five surveys were carried out in different years. The correction factor was estimated also for the Adriatic Sea, Tyrrhenian Sea and Northern Spain; the observed variability among areas highlighted the importance of the spatial and temporal coverage of the survey area in order to obtain reliable estimates of the correction factor. Further studies are necessary to improve the interpretation of the obtained estimates in relation to area-related peculiarities such as zooplankton composition and abundance along with small pelagic fish community structure
Diagnosi prenatale di piede torto congenito:importanza dell\u27approccio multidisciplinare.
...Definizione Piede torto: Anomalia strutturale del piede , che risulta da un arresto di sviluppo, che fissa il piede in un atteggiamento che ? proprio del periodo precoce della vita embrionaria, con persistenza dell\u27atteggiamento in equinovaro- supinazione. PREVALENZA 1-3 / 1000 nati M : F 2 : 1 - Bilateralit? 65% cas
Report of 14th meeting for MEDiterranean International Acoustic Surveys (MEDIAS) in the framework of European Data Collection Framework (DCF)
Principal components analysis based control of a multi-dof underactuated prosthetic hand
<p>Abstract</p> <p>Background</p> <p>Functionality, controllability and cosmetics are the key issues to be addressed in order to accomplish a successful functional substitution of the human hand by means of a prosthesis. Not only the prosthesis should duplicate the human hand in shape, functionality, sensorization, perception and sense of body-belonging, but it should also be controlled as the natural one, in the most intuitive and undemanding way. At present, prosthetic hands are controlled by means of non-invasive interfaces based on electromyography (EMG). Driving a multi degrees of freedom (DoF) hand for achieving hand dexterity implies to selectively modulate many different EMG signals in order to make each joint move independently, and this could require significant cognitive effort to the user.</p> <p>Methods</p> <p>A Principal Components Analysis (PCA) based algorithm is used to drive a 16 DoFs underactuated prosthetic hand prototype (called CyberHand) with a two dimensional control input, in order to perform the three prehensile forms mostly used in Activities of Daily Living (ADLs). Such Principal Components set has been derived directly from the artificial hand by collecting its sensory data while performing 50 different grasps, and subsequently used for control.</p> <p>Results</p> <p>Trials have shown that two independent input signals can be successfully used to control the posture of a real robotic hand and that correct grasps (in terms of involved fingers, stability and posture) may be achieved.</p> <p>Conclusions</p> <p>This work demonstrates the effectiveness of a bio-inspired system successfully conjugating the advantages of an underactuated, anthropomorphic hand with a PCA-based control strategy, and opens up promising possibilities for the development of an intuitively controllable hand prosthesis.</p
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