Fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids in model membranes is connected not to lipid mobility but to probe location

Nitrobenzoxadiazole (NBD)-labeled lipids are popular fluorescent membrane probes. However, the understanding of important aspects of the photophysics of NBD remains incomplete, including the observed shift in the emission spectrum of NBD-lipids to longer wavelengths following excitation at the red edge of the absorption spectrum (red-edge excitation shift or REES). REES of NBD-lipids in membrane environments has been previously interpreted as reflecting restricted mobility of solvent surrounding the fluorophore. However, this requires a large change in the dipole moment (Dm) of NBD upon excitation. Previous calculations of the value of Dm of NBD in the literature have been carried out using outdated semi-empirical methods, leading to conflicting values. Using up-to-date density functional theory methods, we recalculated the value of Dm and verified that it is rather small (B2 D). Fluorescence measurements confirmed that the value of REES is B16 nm for 1,2-dioleoyl-sn-glycero-3- phospho-L-serine-N-(NBD) (NBD-PS) in dioleoylphosphatidylcholine vesicles. However, the observed shift is independent of both the temperature and the presence of cholesterol and is therefore insensitive to the mobility and hydration of the membrane. Moreover, red-edge excitation leads to an increased contribution of the decay component with a shorter lifetime, whereas time-resolved emission spectra of NBD-PS displayed an atypical blue shift following excitation. This excludes restrictions to solvent relaxation as the cause of the measured REES and TRES of NBD, pointing instead to the heterogeneous transverse location of probes as the origin of these effects. The latter hypothesis was confirmed by molecular dynamics simulations, from which the calculated heterogeneity of the hydration and location of NBD correlated with the measured fluorescence lifetimes/REES. Globally, our combination of theoretical and experiment-based techniques has led to a considerably improved understanding of the photophysics of NBD and a reinterpretation of its REES in particular.

Procedimento dos enfermeiros face ao comportamento agressivo dos utentes no Serviço de Urgência de Psiquiatria

De acordo com as evidências científicas e empíricas, os enfermeiros são frequentemente vítimas de agressão, sendo mais vulneráveis os que trabalham em serviços de urgência psiquiátrica. Perante esta realidade e através de entrevistas semiestruturadas, procurou-se identificar os procedimentos e as dificuldades sentidas pelos enfermeiros, perante o comportamento agressivo dos utentes no serviço de urgência psiquiátrica. Os dados revelaram que nalgumas situações, os enfermeiros conseguem predizer o comportamento agressivo dos utentes, fundamentalmente a partir de expressões não verbais. As estratégias comunicacionais verbais e não verbais, seguido dos vários métodos de contenção, são os procedimentos mais utilizados pelos enfermeiros para lidar com o comportamento agressivo do utente. A insuficiente formação da equipa multidisciplinar e a gestão do espaço físico, foram as principais dificuldades nomeadas pelos enfermeiros; NURSES PROCEDURES TOWARDS PATIENT AGGRESSIVE BEHAVIOR AT PSYCHIATRIC EMERGENCY SERVICES ABSTRACT: The scientific and empirical evidence shows that nurses are often victims of aggression. Those working in psychiatric emergency services are more vulnerable. Due to this reality and by the use of semi-structured interviews we proposed to identify the procedures and difficulties that nurse’s experience due to patients’ aggressive behavior at psychiatric emergency services. According to data, in some cases nurses can predict aggressive behavior. Most of the time, it is possible by observation of patient non-verbal expression. To handle patient’s aggressive behavior nurses used most commonly the verbal and nonverbal communications strategies. When this isn´t enough they used a coercive intervention, such as the restraint methods. For nurses, the main difficulties are the lack of training of the multidisciplinary team and the management of the physical space.

Quantification of free auxins in semi-hardwood plant cuttings and microshoots by dispersive liquid–liquid microextraction/microwave derivatization and GC/MS analysis

Several studies have suggested that differences in the natural rooting ability of plant cuttings could be attributed to differences in endogenous auxin levels. Hence, during rooting experiments, it is important to be able to routinely monitor the evolution of endogenous levels of plant hormones. This work reports the development of a new method for the quantification of free auxins in auxin-treated Olea europaea (L.) explants, using dispersive liquid–liquid microextraction (DLLME) and microwave assisted derivatization (MAD) followed by gas chromatography/mass spectrometry (GC/MS) analysis. Linear ranges of 0.5–500 ng mL 1 and 1–500 mg mL 1 were used for the quantification of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), respectively. Determined by serial dilutions, the limits of detection (LOD) and quantification (LOQ) were 0.05 ng mL 1 and 0.25 ng mL 1, respectively for both compounds. When using the calibration curve for determination, the LOQ corresponded to 0.5 ng mL 1 (IAA) and 0.5 mg mL 1 (IBA). The proposed method proved to be substantially faster than other alternatives, and allowed free auxin quantification in real samples of semi-hardwood cuttings and microshoots of two olive cultivars. The concentrations found in the analyzed samples are in the range of 0.131–0.342 mg g 1 (IAA) and 20–264 mg g 1 (IBA).