Investigating New Applications of a Photoswitchable Fluorescent Norbornadiene as a Multifunctional Probe for Delineation of Amyloid Plaque Polymorphism

Amyloid beta (Aβ) plaques are a major pathological hallmark of Alzheimer’s disease (AD) and constitute of structurally heterogenic entities (polymorphs) that have been implicated in the phenotypic heterogeneity of AD pathology and pathogenesis. Understanding amyloid aggregation has been a critical limiting factor to gain understanding of AD pathogenesis, ultimately reflected in that the underlying mechanism remains elusive. We identified a fluorescent probe in the form of a turn-off photoswitchable norbornadiene derivative (NBD1) with several microenvironment-sensitive properties that make it relevant for applications within advanced fluorescence imaging, for example, multifunctional imaging. We explored the application of NBD1 for in situ delineation of structurally heterogenic Aβ plaques in transgenic AD mouse models. NBD1 plaque imaging shows characteristic broader emission bands in the periphery and more narrow emission bands in the dense cores of mature cored plaques. Further, we demonstrate in situ photoisomerization of NBD1 to quadricyclane and thermal recovery in single plaques, which is relevant for applications within both functional and super-resolution imaging. This is the first time a norbornadiene photoswitch has been used as a probe for fluorescence imaging of Aβ plaque pathology in situ and that its spectroscopic and switching properties have been studied within the specific environment of senile Aβ plaques. These findings open the way toward new applications of NBD-based photoswitchable fluorescent probes for super-resolution or dual-color imaging and multifunctional microscopy of amyloid plaque heterogeneity. This could allow to visualize Aβ plaques with resolution beyond the diffraction limit, label different plaque types, and gain insights into their physicochemical composition

Displacements analysis of self-excited vibrations in turning

The actual research deals with determining by a new protocol the necessary parameters considering a three-dimensional model to simulate in a realistic way the turning process on machine tool. This paper is dedicated to the experimental displacements analysis of the block tool / block workpiece with self-excited vibrations. In connexion with turning process, the self-excited vibrations domain is obtained starting from spectra of two accelerometers. The existence of a displacements plane attached to the tool edge point is revealed. This plane proves to be inclined compared to the machines tool axes. We establish that the tool tip point describes an ellipse. This ellipse is very small and can be considered as a small straight line segment for the stable cutting process (without vibrations). In unstable mode (with vibrations) the ellipse of displacements is really more visible. A difference in phase occurs between the tool tip displacements on the radial direction and on the cutting one. The feed motion direction and the cutting one are almost in phase. The values of the long and small ellipse axes (and their ratio) shows that these sizes are increasing with the feed rate value. The axis that goes through the stiffness center and the tool tip represents the maximum stiffness direction. The maximum (resp. minimum) stiffness axis of the tool is perpendicular to the large (resp. small) ellipse displacements axis. FFT analysis of the accelerometers signals allows to reach several important parameters and establish coherent correlations between tool tip displacements and the static - elastic characteristics of the machine tool components tested

Environmental management decision-making in certified hotels

This paper analyses environmental decision-making against two axes, motivations and decision-making processes, to understand the reasons for pro-environmental behaviour by the managements of Spanish Eco-management and Audit Scheme (EMAS)-certified hotels. Mixed methods were used to study perceptions of EMAS and reasons for being certified, with current and lapsed EMAS-certified firms triangulated against expert interviews and documentary evidence. Four groups of hotels were differentiated: Strategic hotels (22%) (with high levels of integrated environmental management), Followers (48%), Greenwashers (11%) and Laggers (19%) (with low levels of integrated environmental management). Most hotels were found to be internally driven in their purpose and ad hoc in their decision-making, with limited understanding of externally driven benefits and motivation for more systematic management systems. This questions the success of EMAS as both a continuous improvement management and as a market-based regulation tool for hotels. Few hotels overall related high environmental standards to the possibilities of gaining market advantage: most wished to avoid legal challenges. The paper also illustrates the ways in which hotels opportunistically switch certification systems to get what they see as a better deal. © 2011 Taylor & Francis

Methodenevaluierung der Quantifizierung verwitterungsrelevanter organischer Säuren aus Böden

Niedermolekulare Organische Säuren (NOS) spielen eine zentrale Rolle bei der pflanzlichen Nährstoffmobilisierung. Insbesondere für die Auflösung von Phosphor- (P) und Eisen (Fe)-Mineralen bzw. der Vorbeugung der P-Fällung durch Chelatisierung zweiwertiger Kationen sind diese Verbindungen von erheblicher Bedeutung. Durch eine Absenkung des pH-Wertes erschweren NOS die Bildung sekundärer Minerale. Über die Komplexierung von Fe oder Calcium (Ca) wird die Verwitterung von primären Eisenmineralen und Apatit vorangetrieben, wodurch NOS aktiv an der Gesteinsverwitterung beteiligt sind. Eine Quantifizierung der NOS im Boden ist somit unerlässlich um diesen Schlüsselprozess der Mineralverwitterung und Pflanzenernährung genauer zu erfassen. In der vorliegenden Studie werden drei verschiedene, bereits publizierte Methoden zur Extraktion und anschließenden Quantifizierung von NOS miteinander verglichen und hinsichtlich ihrer Vor- und Nachteile bezüglich spezifischer Fragestellungen evaluiert. Bei den auf Gaschromatographie-Massenspektrometrie (GC-MS) beruhenden Methoden ist eine Derivatisierung der Analyten notwendig, wobei hier eine Butylierung mit einer Methylierung verglichen wird. Die dritte auf Hochleistungsflüssigchromatographie-Massenspektrometrie (HPLC-MS) basierende Methode kommt ohne Derivatisierung der Analyten aus. Die angewendete sequentielle Extraktionsmethode mit 1) der Extraktion wasserlöslicher NOS und 2) einer schwach sauren Extraktion erlaubt die Unterscheidung wasserlöslicher von mineralassoziierten NOS. Die Methoden wurden hinsichtlich Nachweisstärke und Reproduzierbarkeit, sowie ihrer Anwendbarkeit für verschiedener Fragestellungen verglichen. Insbesondere zur Bestimmung von NOS an C-13 markierten Proben ist eine Methode wünschenswert bei dem die Menge an Fremdkohlenstoff im Molekül minimiert wird. Hier stellt die HPLC-MS Methode die beste Alternative dar, bringt jedoch messtechnisch einige Herausforderungen mit sich. Der präparative Aufwand ist deutlich geringer als bei den anderen Methoden, was einen höheren Probendurchsatz ermöglicht. Allerdings kann mit einer HPLC-MS Methode nicht die Nachweisstärke und Sensitivität der GC-MS Methoden erreicht werden. Darüber hinaus stellt die Lagerung der mikrobiell extrem schnell abbaubaren NOS als underivatisierte LC-MS Proben oft ein Problem dar; Derivatisierung und nachfolgende Lagerung in organischen Lösemitteln verbessern die Haltbarkeit und damit das Zeitfenster für die Messung erheblich

A Human Stem Cell-Derived Neuronal Model of Morphine Exposure Reflects Brain Dysregulation in Opioid Use Disorder: Transcriptomic and Epigenetic Characterization of Postmortem-Derived iPSC Neurons

INTRODUCTION: Human-derived induced pluripotent stem cell (iPSC) models of brain promise to advance our understanding of neurotoxic consequences of drug use. However, how well these models recapitulate the actual genomic landscape and cell function, as well as the drug-induced alterations, remains to be established. New METHODS: We engineered a novel induced pluripotent stem cell-derived model of neural progenitor cells and neurons from cultured postmortem human skin fibroblasts, and directly compared these to isogenic brain tissue from the donor source. We assessed the maturity of the cell models across differentiation from stem cells to neurons using RNA cell type and maturity deconvolution analyses as well as DNA methylation epigenetic clocks trained on adult and fetal human tissue. As proof-of-concept of this model\u27s utility for substance use disorder studies, we compared morphine- and cocaine-treated neurons to gene expression signatures in postmortem Opioid Use Disorder (OUD) and Cocaine Use Disorder (CUD) brains, respectively. RESULTS: Within each human subject (N = 2, 2 clones each), brain frontal cortex epigenetic age parallels that of skin fibroblasts and closely approximates the donor\u27s chronological age; stem cell induction from fibroblast cells effectively sets the epigenetic clock to an embryonic age; and differentiation of stem cells to neural progenitor cells and then to neurons progressively matures the cells DISCUSSION: In summary, we introduce an iPSC model generated from human postmortem fibroblasts that can be directly compared to corresponding isogenic brain tissue and can be used to model perturbagen exposure such as that seen in opioid use disorder. Future studies with this and other postmortem-derived brain cellular models, including cerebral organoids, can be an invaluable tool for understanding mechanisms of drug-induced brain alterations

V-shaped pyranylidene/triphenylamine-based chromophores with enhanced photophysical, electrochemical and nonlinear optical properties

We report the synthesis and comprehensive study of two chromophores based on 4H-pyranylidene moiety as a part of the p-conjugated spacer. Triphenylamine (TPA) acts as donor and tricarbonitrile-based electron-accepting groups complete these V-shaped D-A-D architectures (A, acceptor; D, donor). Their electrochemical, photophysical and nonlinear optical properties are analyzed in detail by using a joint experimental and theoretical approach. The two chromophores exhibit near-infrared fluorescence, large Stokes shift, enhanced emission in tetrahydrofuran/water mixtures and good photostability. Additionally, the dimerization of triphenylamine groups to tetraphenylbenzidine (TPB) takes place upon electrochemical and chemical oxidation showing their peculiar electrochemical behavior and film formation capabilities. Interestingly, high molecular first hyperpolarizabilities and two-photon absorption cross-sections were found, highlighting their potential applications in electro-optical devices. Overall, our work demonstrates that these near-infrared (NIR) fluorescent chromophores are versatile materials with a myriad of applications ranging from optoelectronics to biological applications. © 2021 The Royal Society of Chemistry