62 research outputs found
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Probing the Mechanochemistry of Metal-Organic Frameworks with Low-Frequency Vibrational Spectroscopy
The identification and characterization of low-frequency vibrational motions of metal-organic frameworks (MOFs) allows for a better understanding of their mechanical and structural response upon perturbation by external stimuli such as temperature, pressure, and adsorption. Here, we describe the combination of an experimental temperature- and pressure-dependent terahertz spectroscopy system with quantum mechanical simulations to measure and assign specific low-frequency vibrational modes that directly drive the mechanochemical properties of this important class of porous materials. More specifically, those intense spectral features in the terahertz region of the vibrational spectrum of ZIF-8 are identified, which are directly connected to its mechanochemical response. In particular, the mechanical compressibility of pristine ZIF-8 is found to follow a peculiar non-linear trend upon pressure: its bulk modulus initially increases up to 0.1 GPa and decreases at higher pressures, which is simultaneously reflected in the terahertz vibrational spectra. This work highlights the interplay between structural, vibrational, and mechanochemical phenomena, all of which are key to the effective exploitation of MOFs. The importance of terahertz vibrational motions on the function of MOFs is demonstrated, and a method presented for their measurement and interpretation, which can be applied widely to any supramolecular material
The evolving place of incretin-based therapies in type 2 diabetes
Treatment options for type 2 diabetes based on the action of the incretin hormone glucagon-like peptide-1 (GLP-1) were first introduced in 2005. These comprise the injectable GLP-1 receptor agonists solely acting on the GLP-1 receptor on the one hand and orally active dipeptidyl-peptidase inhibitors (DPP-4 inhibitors) raising endogenous GLP-1 and other hormone levels by inhibiting the degrading enzyme DPP-4. In adult medicine, both treatment options are attractive and more commonly used because of their action and safety profile. The incretin-based therapies stimulate insulin secretion and inhibit glucagon secretion in a glucose-dependent manner and carry no intrinsic risk of hypoglycaemia. GLP-1 receptor agonists allow weight loss, whereas DPP-4 inhibitors are weight neutral. This review gives an overview of the mechanism of action and the substances and clinical data available
Brain energy rescue:an emerging therapeutic concept for neurodegenerative disorders of ageing
The brain requires a continuous supply of energy in the form of ATP, most of which is produced from glucose by oxidative phosphorylation in mitochondria, complemented by aerobic glycolysis in the cytoplasm. When glucose levels are limited, ketone bodies generated in the liver and lactate derived from exercising skeletal muscle can also become important energy substrates for the brain. In neurodegenerative disorders of ageing, brain glucose metabolism deteriorates in a progressive, region-specific and disease-specific manner — a problem that is best characterized in Alzheimer disease, where it begins presymptomatically. This Review discusses the status and prospects of therapeutic strategies for countering neurodegenerative disorders of ageing by improving, preserving or rescuing brain energetics. The approaches described include restoring oxidative phosphorylation and glycolysis, increasing insulin sensitivity, correcting mitochondrial dysfunction, ketone-based interventions, acting via hormones that modulate cerebral energetics, RNA therapeutics and complementary multimodal lifestyle changes
Investigating large-scale brain dynamics using field potential recordings: Analysis and interpretation
New technologies to record electrical activity from the brain on a massive scale offer tremendous opportunities for discovery. Electrical measurements of large-scale brain dynamics, termed field potentials, are especially important to understanding and treating the human brain. Here, our goal is to provide best practices on how field potential recordings (EEG, MEG, ECoG and LFP) can be analyzed to identify large-scale brain dynamics, and to highlight critical issues and limitations of interpretation in current work. We focus our discussion of analyses around the broad themes of activation, correlation, communication and coding. We provide best-practice recommendations for the analyses and interpretations using a forward model and an inverse model. The forward model describes how field potentials are generated by the activity of populations of neurons. The inverse model describes how to infer the activity of populations of neurons from field potential recordings. A recurring theme is the challenge of understanding how field potentials reflect neuronal population activity given the complexity of the underlying brain systems
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Research data supporting "Pharmaceutical film coating catalogue for spectral-domain optical coherence tomography"
The data set contains the optical coherence tomography images presented in the publication
Combined preoperative onyx embolization and protective internal carotid artery covered stent placement for treatment of glomus vagale tumor: review of literature and illustrative case
Objective: Surgical resection of complex glomus vagale tumors can be complicated by extensive blood loss and might require surgical sacrifice of an encased internal carotid artery.
Methods: A young patient presented with mass effect from glomus valage tumor. Computerized tomorgraphy angiography showed an encased internal carotid artery. Cerebral angiography demonstrated a highly vascular tumor. A literature review was performed for endovascular treatment options for neck tumors.
Results: Staged preoperative embolization of feeder arteries via internal maxillary artery, and thyrocervical trunk with Onyx was performed. A covered stent was implanted in the cervical internal carotid artery to the common carotid artery; this resulted in complete devascularization of the tumor with exclusion of external carotid artery from the circulation. This is followed by surgical resection of the tumor.
Conclusion: Preoperative embolization with Onyx decreased the amount of blood loss intra-operatively. The implantation of a covered stent in the cervical internal carotid artery through the common carotid artery contributed for further devasculatization of the tumor bed, as well as provided a lumen continuity in case iatrogenic carotid injury is encountered intra-operativel
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