202 research outputs found
Electronic structure of an iron porphyrin derivative on Au(1 1 1)
Surface-bound porphyrins are promising candidates for molecular switches, electronics and spintronics. Here, we studied the structural and the electronic properties of Fe-tetra-pyridil-porphyrin adsorbed on Au(1 1 1) in the monolayer regime. We combined scanning tunneling microscopy/spectroscopy, ultraviolet photoemission, and two-photon photoemission to determine the energy levels of the frontier molecular orbitals. We also resolved an excitonic state with a binding energy of 420 meV, which allowed us to compare the electronic transport gap with the optical gap
Correlation of vibrational excitations and electronic structure with submolecular resolution
The detection of vibrational excitations of individual molecules on surfaces by scanning tunneling spectroscopy does not obey strict selection rules but rather propensity rules. The experimental verification of these excitations is challenging because it requires the independent variation of specific parameters, such as the electronic structure, while keeping the vibrational modes the same. Here, we make use of the versatile self-assembled structures of Fe-tetra-pyridyl-porphyrin molecules on a Au(111) surface. These molecules exhibit different energy-level alignments of the frontier molecular orbitals, thus allowing the correlation of the electronic structure and detection of vibrations. We identify up to seven vibrational modes in the tunneling spectra of the molecules in some of the arrangements, whereas we observe none in other structures. We find that the presence of vibrational excitations and their distribution along the molecule correlate with the observation of energetically low-lying molecular states. This correlation allows the explanation of the different numbers of vibrational signatures for molecules embedded within different structures as well as the bias asymmetry of the vibrational intensities within an individual molecule. Our observations are in agreement with the resonant enhancement of vibrations by the virtual excitation of electronic states
Immunopeptidomics toolkit library (IPTK): a python-based modular toolbox for analyzing immunopeptidomics data
Background The human leukocyte antigen (HLA) proteins play a fundamental role in the adaptive immune system as they present peptides to T cells. Mass-spectrometry-based immunopeptidomics is a promising and powerful tool for characterizing the immunopeptidomic landscape of HLA proteins, that is the peptides presented on HLA proteins. Despite the growing interest in the technology, and the recent rise of immunopeptidomics-specific identification pipelines, there is still a gap in data-analysis and software tools that are specialized in analyzing and visualizing immunopeptidomics data. Results We present the IPTK library which is an open-source Python-based library for analyzing, visualizing, comparing, and integrating different omics layers with the identified peptides for an in-depth characterization of the immunopeptidome. Using different datasets, we illustrate the ability of the library to enrich the result of the identified peptidomes. Also, we demonstrate the utility of the library in developing other software and tools by developing an easy-to-use dashboard that can be used for the interactive analysis of the results. Conclusion IPTK provides a modular and extendable framework for analyzing and integrating immunopeptidomes with different omics layers. The library is deployed into PyPI at https://pypi.org/project/IPTKL/ and into Bioconda at https://anaconda.org/bioconda/iptkl , while the source code of the library and the dashboard, along with the online tutorials are available at https://github.com/ikmb/iptoolkit
Novel Schizophrenia Risk Gene TCF4 Influences Verbal Learning and Memory Functioning in Schizophrenia Patients
Background: Recently, a role of the transcription factor 4 (TCF4) gene in schizophrenia has been reported in a large genome-wide association study. It has been hypothesized that TCF4 affects normal brain development and TCF4 has been related to different forms of neurodevelopmental disorders. Schizophrenia patients exhibit strong impairments of verbal declarative memory (VDM) functions. Thus, we hypothesized that the disease-associated C allele of the rs9960767 polymorphism of the TCF4 gene led to impaired VDM functioning in schizophrenia patients. Method: The TCF4 variant was genotyped in 401 schizophrenia patients. VDM functioning was measured using the Rey Auditory Verbal Learning Test (RAVLT). Results: Carriers of the C allele were less impaired in recognition compared to those carrying the AA genotype (13.76 vs. 13.06; p = 0.049). Moreover, a trend toward higher scores in patients with the risk allele was found for delayed recall (10.24 vs. 9.41; p = 0.088). The TCF4 genotype did not influence intelligence or RAVLT immediate recall or total verbal learning. Conclusion: VDM function is influenced by the TCF4 gene in schizophrenia patients. However, the elevated risk for schizophrenia is not conferred by TCF4-mediated VDM impairment. Copyright (C) 2011 S. Karger AG, Base
Natural Ventilation Building Design Approach in Mediterranean Regions A Case Study at the Valencian Coastal Regional Scale (Spain)
[EN] Environmental awareness has led to an increased concern about low carbon technologies implementation. Among these technologies, the following research is focused on the natural ventilation effect evaluation in buildings prior to its construction. The aim is to select the most suitable architectural solution to ensure comfortable indoor environment in the most efficient way in the early building design stage. The design approach takes into account the wind conditions in the region and the building surroundings to evaluate the façade opening distribution impact on natural ventilation performance. The design approach is based on computational fluid dynamics (CFD). In this article, a case study located in the Valencian Community (Spain) is depicted. The Valencian Community coastal climatic conditions are evaluated to assess the low carbon technology energy saving potential. Moreover, the main drivers and barriers involved in the design approach implementation in the region are discussed. The conclusions show that the natural ventilation design approach can improve up to 9.7% the building energy performance respect an initial building design, in which natural ventilation has not been considered. The results contribute to an assessment of the complete low carbon technology effect in the region.Mora-Pérez, M.; Guillén Guillamón, IE.; López-Patiño, G.; López Jiménez, PA. (2016). Natural Ventilation Building Design Approach in Mediterranean Regions A Case Study at the Valencian Coastal Regional Scale (Spain). Sustainability. 8(9):1-15. doi:10.3390/su8090855S1158
Circulating adenosine increases during human experimental endotoxemia but blockade of its receptor does not influence the immune response and subsequent organ injury
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95720.pdf (publisher's version ) (Open Access)INTRODUCTION: Preclinical studies have shown that the endogenous nucleoside adenosine prevents excessive tissue injury during systemic inflammation. We aimed to study whether endogenous adenosine also limits tissue injury in a human in vivo model of systemic inflammation. In addition, we studied whether subjects with the common 34C > T nonsense variant (rs17602729) of adenosine monophosphate deaminase (AMPD1), which predicts increased adenosine formation, have less inflammation-induced injury. METHODS: In a randomized double-blinded design, healthy male volunteers received 2 ng/kg E. Coli LPS intravenously with (n = 10) or without (n = 10) pretreatment with the adenosine receptor antagonist caffeine (4 mg/kg body weight). In addition, lipopolysaccharide (LPS) was administered to 10 subjects heterozygous for the AMPD1 34C > T variant. RESULTS: The increase in adenosine levels tended to be more pronounced in the subjects heterozygous for the AMPD1 34C > T variant (71 +/- 22%, P=0.04), compared to placebo- (59 +/- 29%, P=0.012) and caffeine-treated (53 +/- 47%, P=0.29) subjects, but this difference between groups did not reach statistical significance. Also the LPS-induced increase in circulating cytokines was similar in the LPS-placebo, LPS-caffeine and LPS-AMPD1-groups. Endotoxemia resulted in an increase in circulating plasma markers of endothelial activation [intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM)], and in subclinical renal injury, measured by increased urinary excretion of tubular injury markers. The LPS-induced increase of these markers did not differ between the three groups. CONCLUSIONS: Human experimental endotoxemia induces an increase in circulating cytokine levels and subclinical endothelial and renal injury. Although the plasma adenosine concentration is elevated during systemic inflammation, co-administration of caffeine or the presence of the 34C > T variant of AMPD1 does not affect the observed subclinical organ damage, suggesting that adenosine does not affect the inflammatory response and subclinical endothelial and renal injury during human experimental endotoxemia. TRIAL REGISTRATION: ClinicalTrials (NCT): NCT00513110
Atrial Natriuretic Peptide Induces Postprandial Lipid Oxidation in Humans
OBJECTIVE—Atrial natriuretic peptide (ANP) regulates arterial blood pressure. In addition, ANP has recently been shown to promote human adipose tissue lipolysis through cGMP-mediated hormone-sensitive lipase activation. We hypothesized that ANP increases postprandial free fatty acid (FFA) availability and energy expenditure while decreasing arterial blood pressure
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