Activity

The measurement of fluorescence spectra and the determination of fluorescence quantum yields in transparent samples are conceptually simple tasks, but these procedures are subject to several pitfalls that can lead to significant errors. Available technical reports and protocols often assume that the reader possesses a solid theoretical background in spectroscopy and has ample experience with fluorescence instrumentation, but this is often not the case given the many applications of fluorescence in diverse fields of science. The goal of this tutorial is to provide a didactic treatment of the topic that will hopefully be accessible to readers without extensive expertise in the field of fluorescence. The article covers the theoretical background needed to understand the origins of the most common artifacts researchers can expect. Possible artifacts are illustrated with examples to help readers avoid them or identify them if present. A step-by-step example of a fluorescence quantum yield determination in solution is provided with detailed experimental information to help readers understand how to design and analyze experiments. © 2020 IOP Publishing Ltd.Inducing electrostatic doping in 2D materials by laser exposure (photodoping effect) is an exciting route to tune optoelectronic phenomena. However, there is a lack of investigation concerning in what respect the action of photodoping in optoelectronic devices is local. Here, we employ scanning photocurrent microscopy (SPCM) techniques to investigate how a permanent photodoping modulates the photocurrent generation in MoS2 transistors locally. We claim that the photodoping fills the electronic states in MoS2 conduction band, preventing the photon-absorption and the photocurrent generation by the MoS2 sheet. Moreover, by comparing the persistent photocurrent (PPC) generation of MoS2 on top of different substrates, we elucidate that the interface between the material used for the gate and the insulator (gate-insulator interface) is essential for the photodoping generation. Our work gives a step forward to the understanding of the photodoping effect in MoS2 transistors and the implementation of such an effect in integrated devices. © 2020 IOP Publishing Ltd.Single molecule localization microscopy (SMLM) allows the imaging of cellular structures with resolutions five to ten times below the diffraction limit of optical microscopy. It was originally introduced as a two-dimensional technique based on the localization of single emitters as projection onto the x-y imaging plane. The determination of the axial position of a fluorescent emitter is only possible by additional information. Here we report a method (spatial filter SMLM (SFSMLM)) that allows to determine the axial positions of fluorescent molecules and nanoparticles on the nanometer scale by the usage of two spatial filters, which are placed in two otherwise identical emission detection channels. SFSMLM allows axial localization in a range of ca. 1.5 μm with a localization precision of 15 – 30 nm in axial direction. The technique was utilized for localizing and imaging small cellular structures – e.g. actin filaments, vesicles and mitochondria – in three dimensions.PURPOSE This study examined the association between self-perceived actual and ideal body sizes and objectively assessed moderate-to-vigorous physical activity (MVPA) among adolescents, controlling for puberty, fat mass index, and sex. A secondary objective was to explore the association between objectively assessed fat mass index and MVPA. METHODS Participants were 438 early adolescents (Mage = 11.61, SD = 0.92). Participants selected body sizes that represented their self-perceived actual and ideal bodies. Participants then wore an accelerometer for 1 week to assess MVPA. Polynomial regression analysis with response surface methods was used to explore MVPA in relation to the discrepancy and agreement (ie, no discrepancy) between self-perceived actual and ideal body sizes. RESULTS When self-perceived actual and ideal body sizes were in agreement and represented smaller and larger bodies, MVPA was low. Participants with similar self-perceived actual and ideal bodies in the middle of the body-size spectrum demonstrated the highest levels of MVPA. The direction and degree of the discrepancy between self-perceived actual and ideal bodies were not significantly associated with MVPA. Fat mass index was significantly and negatively associated with MVPA. CONCLUSIONS These findings may inform physical activity promotion programs and provide methodological contributions to the study of how body image and MVPA are related.BACKGROUND Children and adolescents with disabilities often report low levels of physical activity (PA). Estimating the magnitude of PA disparities has been previously challenged by underreporting and variability in subsampling of disability. Using the National Survey of Children’s Health, this study estimated the population-level PA disparities experienced and the association between disability status and PA engagement. Selleckchem HC-7366 METHODS Weighted prevalence of PA engagement (National Physical Activity Guidelines for Americans (2nd edition) and sports participation) was compared across disability groups for children (n = 20,867, 6-11 y) and adolescents (n = 28,651, 12-17 y) and found to be 12%. Age-stratified multivariable logistic regressions estimated the likelihood of PA engagement as a function of disability status and type, after adjusting for child and household factors. RESULTS Children, but not adolescents, with disabilities had significantly lower odds of being sufficiently active compared with peers without disabilities (adjusted odds ratio = 0.75; 95% confidence interval, 0.60-0.94). Across age groups, the lowest prevalence rates were observed among those experiencing function and mobility disabilities. Children and adolescents were significantly less likely to participate in sports compared with peers. CONCLUSION Children with function and mobility disabilities were identified as priority subpopulations least likely to be sufficiently active. The disparity in sports participation highlights a critical intervention point for increasing PA among children with disabilities.