Surface-initiated atom transfer radical polymerization (SI-ATRP) has become an indispensable tool for engineering the structure and properties of polymer/inorganic and polymer/organic interfaces. ...This article describes the progress and challenges that are associated with the application of SI-ATRP to precisely control the molecular characteristics of polymer chains tethered to nanoparticle surfaces and explores the properties and potential applications of the resulting particle brush materials. Even for the conceptually most “simple” particle brush systemsthat is, spherical particles uniformly grafted with amorphous nonpolar polymersthe complex superposition of interactions as well as time- and length-scales related to particle core and tethered chains provides a rich and largely unexplored parameter space for the design of novel functional materials. The application of the particle brush approach to the development of materials for applications ranging from photonic inks and paints to advanced high “k” dielectrics for energy storage and advanced nanocomposite materials with improved optical, mechanical, or transport characteristics is discussed.
Deriving the extent of areas affected by wildfires is critical to fire management, protection of the population, damage assessment, and better understanding of the consequences of fires. In the past ...two decades, several algorithms utilizing data from Earth observation satellites have been developed to detect fire-affected areas. However, most of these methods require the establishment of complex functional relationships between numerous remote sensing data parameters. In contrast, more recently, deep learning has found its way into the application, having the advantage of being able to detect patterns in complex data by learning from examples automatically. In this article, a workflow for the detection of fire-affected areas from satellite imagery acquired in the visible, infrared, and microwave domains is described. Using this workflow, the fire detection potentials of four sources of freely available satellite imagery were investigated: the C-SAR instrument on board Sentinel-1, the multispectral instrument on board Sentinel-2, the sea and land surface temperature instrument on board Sentinel-3, and the MODIS instrument on board Terra and Aqua. For each of them, a single-input convolutional neural network based on the well-known U-Net architecture was trained on a newly created dataset. The performance of the resulting four single-instrument models was evaluated in presence of clouds and in clear conditions. In addition, the potential of combining predictions from pairs of single-instrument models was investigated. The results show that fusion of Sentinel-2 and Sentinel-3 data provides the best detection rate in clear conditions, whereas the fusion of Sentinel-1 and Sentinel-2 data shows a significant benefit in cloudy weather.
Due to its all time capability, synthetic aperture radar (SAR) remote sensing plays an important role in Earth observation. The ability to interpret the data is limited, even for experts, as the ...human eye is not familiar to the impact of distance-dependent imaging, signal intensities detected in the radar spectrum as well as image characteristics related to speckle or steps of post-processing. This paper is concerned with machine learning for SAR-to-optical image-to-image translation in order to support the interpretation and analysis of original data. A conditional adversarial network is adopted and optimized in order to generate alternative SAR image representations based on the combination of SAR images (starting point) and optical images (reference) for training. Following this strategy, the focus is set on the value of empirical knowledge for initialization, the impact of results on follow-up applications, and the discussion of opportunities/drawbacks related to this application of deep learning. Case study results are shown for high resolution (SAR: TerraSAR-X, optical: ALOS PRISM) and low resolution (Sentinel-1 and -2) data. The properties of the alternative image representation are evaluated based on feedback from experts in SAR remote sensing and the impact on road extraction as an example for follow-up applications. The results provide the basis to explain fundamental limitations affecting the SAR-to-optical image translation idea but also indicate benefits from alternative SAR image representations.
Corynebacterium diphtheriae is a Gram-positive bacterial pathogen and the causative agent of diphtheria, a severe disease of the upper respiratory tract of humans. Factors required for C. diphtheriae ...to survive in the human host are not well defined, but likely include the acquisition of essential metals such as zinc. In C. diphtheriae, zinc-responsive global gene regulation is controlled by the Zinc Uptake Regulator (Zur), a member of the Fur-family of transcriptional regulators. In this study, we use transcriptomics to identify zinc-regulated genes in C. diphtheriae by comparing gene expression of a wild-type strain grown without and with zinc supplementation. Zur-regulated genes were identified by comparing wild-type gene expression with that of an isogenic zur mutant. We observed zinc repression of several putative surface proteins, the heme efflux system hrtBA, various ABC transporters, and the non-ribosomal peptide synthetase/polyketide synthase cluster sidAB. Furthermore, increased gene expression in response to zinc was observed for the alcohol dehydrogenase, adhA. Zinc and Zur regulation were confirmed for several genes by complementing the zur deletion and subsequent RT-qPCR analysis. We used MEME to predict Zur binding sites within the promoter regions of zinc- and Zur-regulated genes, and verified Zur binding by electrophoretic mobility shift assays. Additionally, we characterized cztA (dip1101), which encodes a putative cobalt/zinc/cadmium efflux family protein. Deletion of cztA results in increased sensitivity to zinc, but not to cobalt or cadmium. This study advances our knowledge of changes to Zur-dependent global gene expression in response to zinc in C. diphtheriae. The identification of zinc-regulated ABC transporters herein will facilitate future studies to characterize zinc transport in C. diphtheriae.
We examined the mechanisms by which ingroup identification impacts well‐being in stigmatized groups. Studies 1–3a were conducted among gay people in Europe and North America. Among gay people, the ...results suggest identification with homosexuals protected well‐being via a decrease in self‐group distancing (Studies 1–3a, N = 1,055). Other coping strategies were associated with identification but had no relationship with well‐being. Identification was positively related to engagement coping strategies (i.e., collective action, group affirmation and ingroup support), and negatively related to disengagement strategies (i.e., ingroup blaming and avoidance of discrimination). Study 3b examined these mechanisms among Black Americans (N = 203). Again, identification was positively related to engagement coping, and negatively to disengagement; however, only collective action (positively) predicted well‐being. Results are discussed in terms of how the effectiveness of different strategies for coping with stigma will differ depending on features of the intergroup context, such as the level of permeability of intergroup boundaries.
The Corynebacterium diphtheriae hemoglobin-binding protein HbpA is critical for the acquisition of iron from the hemoglobin-haptoglobin complex (Hb-Hp). Previous studies using C. diphtheriae strain ...1737 showed that large aggregates formed by HbpA are associated with iron transport activity and enhanced binding to Hb-Hp; however, specific regions within HbpA required for Hb-Hp binding or iron uptake have not been identified. In this study, we characterized two clinical isolates from Austria, designated 07-18 and 09-15, which express HbpA proteins that share only 53% and 44% sequence identity, respectively, to the strain 1737 HbpA protein. The HbpA proteins expressed by the Austrian strains had functional and structural properties similar to those of the HbpA protein in strain 1737 despite the limited sequence similarity. These shared characteristics between the HbpA proteins included similar cellular localization, aggregate formation, and Hb and Hb-Hp binding. Additionally, the Austrian strains were able to acquire iron from Hb and Hb-Hp, and deletion of the
gene from these two clinical isolates reduced their ability to use Hb-Hp as an iron source. A sequence comparison between the HbpA proteins from 1737 and the Austrian strains assisted in the identification of a putative Hb-binding site that shared similar characteristics with the Hb-binding regions in Staphylococcus aureus NEAT domains. Amino acid substitutions within this conserved Hb-binding region significantly reduced Hb and Hb-Hp binding and diminished the hemin-iron uptake function of HbpA. These findings represent important advances in our understanding of the interaction of HbpA with human hemoproteins.
Hemoglobin (Hb) is the primary source of iron in humans, and the acquisition of hemin-iron from Hb is critical for many bacterial pathogens to infect and survive in the human host. In this study, we have examined the C. diphtheriae Hb-binding protein HbpA in two clinical isolates and show that these proteins, despite limited sequence similarity, are functionally equivalent to the previously described HbpA protein in strain 1737. A sequence comparison between these three strains led to the identification of a conserved Hb-binding site, which will further our understanding of how this novel protein functions in hemin-iron transport and, more generally, will expand our knowledge on how Hb interacts with proteins.
Military strategists have begun pivoting from a focus on counterterrorism, counter-insurgency and stability operations to potential peer and near-peer conflict. This shift has profound operational ...and tactical implications for how future wars will be fought, but equally, it will have a significant impact on how international humanitarian law (IHL) is understood and applied. This article considers the process by which the normative evolution of IHL will occur in response to a battlespace that looks different than it has for decades. To do so, the article introduces two concepts: “normative architecture” and “applied IHL”. It argues that only by understanding the difference between these two concepts, and their relationship to each other, can States and others concerned with how IHL is developing in the face of future conflict positively affect that process.
Raman spectroscopy is an emerging technique in bioanalysis and imaging of biomaterials owing to its unique capability of generating spectroscopic fingerprints. Imaging cells and tissues by Raman ...microspectroscopy represents a nondestructive and label‐free approach. All components of cells or tissues contribute to the Raman signals, giving rise to complex spectral signatures. Resonance Raman scattering and surface‐enhanced Raman scattering can be used to enhance the signals and reduce the spectral complexity. Raman‐active labels can be introduced to increase specificity and multimodality. In addition, nonlinear coherent Raman scattering methods offer higher sensitivities, which enable the rapid imaging of larger sampling areas. Finally, fiber‐based imaging techniques pave the way towards in vivo applications of Raman spectroscopy. This Review summarizes the basic principles behind medical Raman imaging and its progress since 2012.
Owing to its unique ability to generate spectroscopic fingerprints, Raman spectroscopy is an emerging technique in bioanalysis and biomaterial imaging. The theory behind this method as well as instrumentation and data‐processing methods are discussed in this Review, and the progress in medical Raman imaging since 2012 is summarized.
Over the last decade, Raman spectroscopy has gained more and more interest in research as well as in clinical laboratories. As a vibrational spectroscopy technique, it is complementary to the also ...well-established infrared spectroscopy. Through specific spectral patterns, substances can be identified and molecular changes can be observed with high specificity. Because of a high spatial resolution due to an excitation wavelength in the visible and near-infrared range, Raman spectroscopy combined with microscopy is very powerful for imaging biological samples. Individual cells can be imaged on the subcellular level. In vivo tissue examinations are becoming increasingly important for clinical applications. In this review, we present currently ongoing research in different fields of medical diagnostics involving linear Raman spectroscopy and imaging. We give a wide overview over applications for the detection of atherosclerosis, cancer, inflammatory diseases and pharmacology, with a focus on developments over the past 5 years. Conclusions drawn from Raman spectroscopy are often validated by standard methods, for example, histopathology or PCR. The future potential of Raman spectroscopy and its limitations are discussed in consideration of other non-linear Raman techniques.
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