1,721,025 research outputs found
Mi spezzo e mi piego”. Posture, sollevamenti e disturbi muscoloscheletrici tra insegnanti prescolari
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Ultra-bright and stimuli-responsive fluorescent nanoparticles for bioimaging
No full textFluorescent nanoparticles (NPs) are unique contrast agents for bioimaging. Examples of molecular-based fluorescent NPs with brightness similar or superior to semiconductor quantum dots have been reported. These ultra-bright NPs consist of a silica or polymeric matrix that incorporate the emitting dyes as individual moieties or aggregates and promise to be more biocompatible than semiconductor quantum dots. Ultra-bright materials result from heavy doping of the structural matrix, a condition that entails a close mutual proximity of the doping dyes. Ground state and excited state interactions between the molecular emitters yield aggregation-caused quenching (ACQ) and proximity-caused quenching (PCQ). In combination with Föster resonance energy transfer (FRET) ACQ and PCQ originate collective phenomena that produce amplified quenching of the nanoprobes. In this focus article, we discuss strategies to achieve ultra-bright nanoprobes avoiding ACQ and PCQ also exploiting aggregation-induced emission (AIE). Amplified quenching, on the other hand, is also proposed as a strategy to design stimuli-responsive fluorogenic probes through disaggregation-induced emission (DIE) in alternative to AIE. As an advantage, DIE consents to design stimuli-responsive materials starting from a large variety of precursors. On the contrary, AIE is characteristic of a limited number of species. Examples of stimuli-responsive fluorogenic probes based on DIE are discussed
Towards Ultra-Bright Gold Nanoclusters
No full textFluorescence bioimaging is a non-invasive technique that permits to investigate living organism in real time with high tridimensional resolution. Properly engineered fluorescent (or photoluminescent) nanoparticles promise to surpass conventional fluorescent molecular probes as contrast agent. Photoluminescent semiconductor quantum dots show, for example, enhanced brightness and photostability. Concerns arising from the toxic metal content of quantum dots prompted the search for alternative inorganic nanoparticles with similar properties but less hazardous. Gold is almost unanimously considered to be highly tolerated by living organism and the environment. Nevertheless, although photoluminescence of gold nanocluster is known by decades, brightness of these nanoparticles has typically reported to be low, mostly because of the poor photoluminescence quantum yield (< 1 %). Different approaches have been proposed to enhance this poor quantum yield aiming to achieve ultra-bright gold nanoparticles with features superior to conventional dyes. Here most relevant and recent results in this direction are summarized and critically discussed
Work From Home During the COVID-19 Outbreak: The Impact on Employees' Remote Work Productivity, Engagement, and Stress
Full text linkObjective: The COVID-19 pandemic made working from home (WFH) the new way of working. This study investigates the impact that family-work conflict, social isolation, distracting environment, job autonomy, and self-leadership have on employees' productivity, work engagement, and stress experienced when WFH during the pandemic.
Methods: This cross-sectional study analyzed data collected through an online questionnaire completed by 209 employees WFH during the pandemic. The assumptions were tested using hierarchical linear regression.
Results: Employees' family-work conflict and social isolation were negatively related, while self-leadership and autonomy were positively related, to WFH productivity and WFH engagement. Family-work conflict and social isolation were negatively related to WFH stress, which was not affected by autonomy and self-leadership.
Conclusion: Individual- and work-related aspects both hinder and facilitate WFH during the COVID-19 outbreak
Tracking graphene by fluorescence imaging: A tool for detecting multiple populations of graphene in solution
No full textMost methods used for the characterization of graphene produced by liquid phase exfoliation require the deposition of the liquid sample on a substrate and subsequent drying. Because of this or other post-synthetic treatments, the reliability of the data in describing the actual features of the graphene particles in the pristine solution becomes questionable. Hence there is a need for new methods that permit the study of graphene directly in solution. Fluorescence imaging is at present the most convenient and sensitive method to visualize nanosized objects in solution. Here we report the development of a new method for visualizing and tracking exfoliated graphene directly in solution using a conventional set-up for fluorescence microscopy. We functionalized a fluorescent surfactant typically used for exfoliating graphite in aqueous phase (Pluronic P123) with two different fluorophores, in order to make graphene detectable by fluorescence microscopy. The photophysical interactions between the fluorescent surfactant and graphene were investigated at the bulk level. Finally, fluorescence microscopy allowed us to track the carbon particles produced and to identify two different populations of particles with sizes of 265 ± 25 and 1100 ± 200 nm respectively. The correlation of these results with TEM and DLS data is discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Luminescent gold nanoclusters as biocompatible probes for optical imaging and theranostics
No full textOptical bioimaging is a powerful tool for investigating living organisms in real time and space, both in-vivo and in-vitro. As an advantage, luminescence based techniques are poorly invasive and highly sensitive when compared to other diagnostic approaches. In order to exploit these attractive features, the search of highly biocompatible contrast agents with spectral controllable signatures and good photostability is needed. Gold nanoclusters (GNCs) based probes promise to merge all these characteristics, being their emission tunable from the visible (VIS) to the near infrared region (NIR), a spectral window ideal for photo-activation and detection in-vivo. In this review article, examples of the most recent applications of GNCs to in-vitro and in-vivo imaging are discussed, also considering the development and the use of multimodal and multifunctional probes, able to combine diagnostic and therapeutic (theranostic) actions. Brightness, photostability and toxicity of GNCs in biological systems are critically analyzed. For a complete overview, the origin of the optical properties of GNCs, as well as their preparation, is briefly discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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