Understanding effects of bioethanol fuel use on urban air quality: An integrative approach

AbstractResultsobtained through combining different approaches, and aiming at contributing to the understanding of effects of bioethanol fuelled vehicles on urban air quality, are evaluated. The study is based on the results obtained by measurements, modelling and cost assessment estimates in a case study in Oslo under winter conditions, when the worst air quality episodes are registered and acetaldehyde and formaldehyde have the longest lifetime. Detailed levels of formaldehyde emitted by an E95-bus under on-road driving conditions are reported for the first time, and indicate that exposure to these levels may involve a high chance of developing cancer. Emission and air dispersion modelling were applied to evaluate the potential impact on urban environment. The results show that a full implementation of bioethanol (E85-vehicles) may affect urban air quality, subsequently affecting human health. Acetaldehyde emissions were estimated to increase by 233% for a full implementation of bioethanol (E85-vehicles) compared to the baseline (petrol/diesel vehicles), whereas CO2, NOx and exhaust particle emissions from traffic were estimated to decrease by 19%, 50% and 90%, respectively. Output from measurements and the air dispersion model were the basis for an impact assessment and economic valuation of implementing bioethanol fuel in a larger scale. The acetaldehyde-related health risk associated with emissions from bioethanol fuelled vehicles was estimated as oral cavity/pharynx cancer, and the related cost was found to increase by 300% for a full implementation of bioethanol relative to the current situation. Our study only shows part of the picture, and a full evaluation bearing in mind all potential pollutants’ increases and reductions would be needed

Multi-color imaging of sub-mitochondrial structures in living cells using structured illumination microscopy

Source at https://doi.org/10.1515/nanoph-2017-0112. Licensed CC BY-NC-ND 4.0.The dimensions of mitochondria are close to the diffraction limit of conventional light microscopy techniques, making the complex internal structures of mitochondria unresolvable. In recent years, new fluorescence-based optical imaging techniques have emerged, which allow for optical imaging below the conventional limit, enabling super-resolution (SR). Possibly the most promising SR and diffraction-limited microscopy techniques for live-cell imaging are structured illumination microscopy (SIM) and deconvolution microscopy (DV), respectively. Both SIM and DV are widefield techniques and therefore provide fast-imaging speed as compared to scanning based microscopy techniques. We have exploited the capabilities of three-dimensional (3D) SIM and 3D DV to investigate different sub-mitochondrial structures in living cells: the outer membrane, the intermembrane space, and the matrix. Using different mitochondrial probes, each of these sub-structures was first investigated individually and then in combination. We describe the challenges associated with simultaneous labeling and SR imaging and the optimized labeling protocol and imaging conditions to obtain simultaneous three-color SR imaging of multiple mitochondrial regions in living cells. To investigate both mitochondrial dynamics and structural details in the same cell, the combined usage of DV for long-term time-lapse imaging and 3D SIM for detailed, selected time point analysis was a useful strategy

Label-free superior contrast with c-band ultra-violet extinction microscopy

In 1934, Frits Zernike demonstrated that it is possible to exploit the sample’s refractive index to obtain superior contrast images of biological cells. The refractive index contrast of a cell surrounded by media yields a change in the phase and intensity of the transmitted light wave. This change can be due to either scattering or absorption caused by the sample. Most cells are transparent at visible wavelengths, which means the imaginary component of their complex refractive index, also known as extinction coefficient k, is close to zero. Here, we explore the use of c-band ultra-violet (UVC) light for high-contrast high-resolution label-free microscopy, as k is naturally substantially higher in the UVC than at visible wavelengths. Using differential phase contrast illumination and associated processing, we achieve a 7- to 300-fold improvement in contrast compared to visible-wavelength and UVA differential interference contrast microscopy or holotomography, and quantify the extinction coefficient distribution within liver sinusoidal endothelial cells. With a resolution down to 215 nm, we are, for the first time in a far-field label-free method, able to image individual fenestrations within their sieve plates which normally requires electron or fluorescence superresolution microscopy. UVC illumination also matches the excitation peak of intrinsically fluorescent proteins and amino acids and thus allows us to utilize autofluorescence as an independent imaging modality on the same setup

Structured Illumination Microscopy of Biological Structures

Abstract of presentation held at Norwegian Electro-Optics Meeting, Henningsvær, Norway, 2-4 May 2018.Resolution in optical microscopy has long been limited to the Abbe diffraction limit, i.e. about 250 nm laterally for visible wavelengths on a very good microscope. In the last two decades several techniques have been devised to circumvent this limit: an achievement which was recognized with the 2014 Nobel Prize in Chemistry. Structured Illumination Microscopy (SIM) was the first of these techniques to become commercially available, and continues to be the only super-resolution technique which is practically compatible with living cells, while also requiring the least modification to conventional sample-labeling protocols. SIM utilizes Moiré patterns and frequency shifting to improve resolution 2X in each dimension, as well as significantly improve the contrast for the mid-range spatial frequencies. These advances have unlocked a new realm of biological inquiry: the combination of the high biochemical specificity of fluorescent probes with resolution previously only possible with electron microscopy now enables the direct study of sub-organelle colocalization and the dynamics of living cells. Here, we will present both the basics of the SIM technique as well as a sampling of its biological applications from our lab at UiT, including sub-mitochondrial localization and dynamics, sieve-like nanostructures in liver cells, and large-scale visualization of super-resolved cardiac tissue sections, as well as discuss the practical limitations and implications of this work

Label-free nanoscopy enabled by coherent imaging with photonic waveguides

SPIE Article-Sharing Policies https://www.spiedigitallibrary.org/article-sharing-policiesIn this project it was found that Fourier ptychographic microscopy can be improved far beyond its conventional limits via waveguide-based optical systems. Extensive in silico studies showed that images obtained on highrefractive index material waveguide chips in conjunction with hyperspectral illumination light and finely designed waveguide geometries can be combined via a modified phase-retrieval algorithm to yield a resolution below 150 nm

Learning Nanoscale Motion Patterns of Vesicles in Living Cells

Detecting and analyzing nanoscale motion patterns of vesicles, smaller than the microscope resolution (~250 nm), inside living biological cells is a challenging problem. State-of-the-art CV approaches based on detection, tracking, optical flow or deep learning perform poorly for this problem. We propose an integrative approach, built upon physics based simulations, nanoscopy algorithms, and shallow residual attention network to make it possible for the first time to analysis sub-resolution motion patterns in vesicles that may also be of sub-resolution diameter. Our results show state-of-the-art performance, 89% validation accuracy on simulated dataset and 82% testing accuracy on an experimental dataset of living heart muscle cells imaged under three different pathological conditions. We demonstrate automated analysis of the motion states and changed in them for over 9000 vesicles. Such analysis will enable large scale biological studies of vesicle transport and interaction in living cells in the future

Road salt emissions: A comparison of measurements and modelling using the NORTRIP road dust emission model

AbstractDe-icing of road surfaces is necessary in many countries during winter to improve vehicle traction. Large amounts of salt, most often sodium chloride, are applied every year. Most of this salt is removed through drainage or traffic spray processes but a certain amount may be suspended, after drying of the road surface, into the air and will contribute to the concentration of particulate matter. Though some measurements of salt concentrations are available near roads, the link between road maintenance salting activities and observed concentrations of salt in ambient air is yet to be quantified. In this study the NORTRIP road dust emission model, which estimates the emissions of both dust and salt from the road surface, is applied at five sites in four Nordic countries for ten separate winter periods where daily mean ambient air measurements of salt concentrations are available. The model is capable of reproducing many of the salt emission episodes, both in time and intensity, but also fails on other occasions. The observed mean concentration of salt in PM10, over all ten datasets, is 4.2 μg/m3 and the modelled mean is 2.8 μg/m3, giving a fractional bias of −0.38. The RMSE of the mean concentrations, over all 10 datasets, is 2.9 μg/m3 with an average R2 of 0.28. The mean concentration of salt is similar to the mean exhaust contribution during the winter periods of 2.6 μg/m3. The contribution of salt to the kerbside winter mean PM10 concentration is estimated to increase by 4.1 ± 3.4 μg/m3 for every kg/m2 of salt applied on the road surface during the winter season. Additional sensitivity studies showed that the accurate logging of salt applications is a prerequisite for predicting salt emissions, as well as good quality data on precipitation. It also highlights the need for more simultaneous measurements of salt loading together with ambient air concentrations to help improve model parameterisations of salt and moisture removal processes

Virtual labeling of mitochondria in living cells using correlative imaging and physics-guided deep learning

Mitochondria play a crucial role in cellular metabolism. This paper presents a novel method to visualize mitochondria in living cells without the use of fluorescent markers. We propose a physics-guided deep learning approach for obtaining virtually labeled micrographs of mitochondria from bright-field images. We integrate a microscope’s point spread function in the learning of an adversarial neural network for improving virtual labeling. We show results (average Pearson correlation 0.86) significantly better than what was achieved by state-of-the-art (0.71) for virtual labeling of mitochondria. We also provide new insights into the virtual labeling problem and suggest additional metrics for quality assessment. The results show that our virtual labeling approach is a powerful way of segmenting and tracking individual mitochondria in bright-field images, results previously achievable only for fluorescently labeled mitochondria

Fluorescence fluctuation-based super-resolution microscopy using multimodal waveguided illumination

Photonic chip-based total internal reflection fluorescence microscopy (c-TIRFM) is an emerging technology enabling a large TIRF excitation area decoupled from the detection objective. Additionally, due to the inherent multimodal nature of wide waveguides, it is a convenient platform for introducing temporal fluctuations in the illumination pattern. The fluorescence fluctuation-based nanoscopy technique multiple signal classification algorithm (MUSICAL) does not assume stochastic independence of the emitter emission and can therefore exploit fluctuations arising from other sources, as such multimodal illumination patterns. In this work, we demonstrate and verify the utilization of fluctuations in the illumination for super-resolution imaging using MUSICAL on actin in salmon keratocytes. The resolution improvement was measured to be 2.2–3.6-fold compared to the corresponding conventional images

High-resolution visualization and assessment of basal and OXPHOS-induced mitophagy in H9c2 cardiomyoblasts

Mitochondria are susceptible to damage resulting from their activity as energy providers. Damaged mitochondria can cause harm to the cell and thus mitochondria are subjected to elaborate quality-control mechanisms including elimination via lysosomal degradation in a process termed mitophagy. Basal mitophagy is a house-keeping mechanism fine-tuning the number of mitochondria according to the metabolic state of the cell. However, the molecular mechanisms underlying basal mitophagy remain largely elusive. In this study, we visualized and assessed the level of mitophagy in H9c2 cardiomyoblasts at basal conditions and after OXPHOS induction by galactose adaptation. We used cells with a stable expression of a pH-sensitive fluorescent mitochondrial reporter and applied state-of-the-art imaging techniques and image analysis. Our data showed a significant increase in acidic mitochondria after galactose adaptation. Using a machine-learning approach we also demonstrated increased mitochondrial fragmentation by OXPHOS induction. Furthermore, super-resolution microscopy of live cells enabled capturing of mitochondrial fragments within lysosomes as well as dynamic transfer of mitochondrial contents to lysosomes. Applying correlative light and electron microscopy we revealed the ultrastructure of the acidic mitochondria confirming their proximity to the mitochondrial network, ER and lysosomes. Finally, exploiting siRNA knockdown strategy combined with flux perturbation with lysosomal inhibitors, we demonstrated the importance of both canonical as well as non-canonical autophagy mediators in lysosomal degradation of mitochondria after OXPHOS induction. Taken together, our high-resolution imaging approaches applied on H9c2 cells provide novel insights on mitophagy during physiologically relevant conditions. The implication of redundant underlying mechanisms highlights the fundamental importance of mitophagy