Detecting Molecular Rotational Dynamics Complementing the Low-Frequency Terahertz Vibrations in a Zirconium-Based Metal-Organic Framework

We show clear experimental evidence of co-operative terahertz (THz) dynamics observed below 3 THz (~100 cm-1), for a low-symmetry Zr-based metal-organic framework (MOF) structure, termed MIL-140A [ZrO(O2C-C6H4-CO2)]. Utilizing a combination of high-resolution inelastic neutron scattering and synchrotron radiation far-infrared spectroscopy, we measured low-energy vibrations originating from the hindered rotations of organic linkers, whose energy barriers and detailed dynamics have been elucidated via ab initio density functional theory (DFT) calculations. For completeness, we obtained Raman spectra and characterized the alterations to the complex pore architecture caused by the THz rotations. We discovered an array of soft modes with trampoline-like motions, which could potentially be the source of anomalous mechanical phenomena, such as negative linear compressibility and negative thermal expansion. Our results also demonstrate coordinated shear dynamics (~2.5 THz), a mechanism which we have shown to destabilize MOF crystals, in the exact crystallographic direction of the minimum shear modulus (Gmin).Comment: 10 pages, 6 figure

Full Hierarchic Versus Non-Hierarchic Classification Approaches for Mapping Sealed Surfaces at the Rural-Urban Fringe Using High-Resolution Satellite Data

Since 2008 more than half of the world population is living in cities and urban sprawl is continuing. Because of these developments, the mapping and monitoring of urban environments and their surroundings is becoming increasingly important. In this study two object-oriented approaches for high-resolution mapping of sealed surfaces are compared: a standard non-hierarchic approach and a full hierarchic approach using both multi-layer perceptrons and decision trees as learning algorithms. Both methods outperform the standard nearest neighbour classifier, which is used as a benchmark scenario. For the multi-layer perceptron approach, applying a hierarchic classification strategy substantially increases the accuracy of the classification. For the decision tree approach a one-against-all hierarchic classification strategy does not lead to an improvement of classification accuracy compared to the standard all-against-all approach. Best results are obtained with the hierarchic multi-layer perceptron classification strategy, producing a kappa value of 0.77. A simple shadow reclassification procedure based on characteristics of neighbouring objects further increases the kappa value to 0.84

Uptake of Aortic 18F-FDG Is Correlated with Low-Density Lipoprotein Cholesterol and Leptin in a General Population

Objective: This study investigated the relationship between aortic 18F-fluoro-2-deoxy-D-glucose (18F-FDG) uptake and clinical and laboratory findings related to atherosclerosis in a general population. Copyright:Methods: 18F-FDG uptake in the ascending aorta was measured on the positron emission tomography/computed tomography (PET/CT) scans of 211 Japanese adults. The maximum target-to-background ratio (TBR) was compared with clinical and laboratory atherosclerosis findings.Results: By multivariate regression analysis adjusted for age and sex, TBR-ascending aorta (TBR-A) was significantly correlated with various clinical and laboratory parameters, such as body mass index, log visceral fat area, low-density lipoprotein cholesterol (LDL-C), log fasting immunoreactive insulin, log homeostasis model assessment of insulin resistance, log total adiponectin and log-leptin, in all subjects. Furthermore, by multivariate linear regression analysis adjusted for confounding factors, TBR-A was significantly correlated with LDL-C (β=0.001, p=0.03) and log-leptin (β =0.336, p<0.01) in all subjects.Conclusion: TBR-A was significantly correlated with LDL-C and log-leptin independent from confounding factors. Our results suggest that aortic 18F-FDG uptake is a good marker of atherosclerosis, even in a general population

ORGANIC AND AQUEOUS PHASE SEPARATIONS ON METAL-ORGANIC FRAMEWORKS

Metal-Organic Frameworks (MOFs) are a recent class of materials built up from metal ions or clusters held together by organic polycomplexing linkers. The wide variety in building units makes that they offer an unprecedented chemical and structural diversity. The hybrid nature of these materials allows adsorbate interactions both with the inorganic and organic nodes of the framework, creating unique interaction possibilities. Most research is devoted to adsorption and separation of gasses on MOFs, while liquid phase separations especially in aqueous phase are scarcely investigated. Furthermore, when considering the industrial implementation of MOFs as adsorbents their mechanical behaviour during shaping operations should be investigated more deeply. In a first part ofnbsp;thesis, the removal of nitrogen and sulfur compounds fromnbsp;is investigated with several MOFs pursuing different strategies. The direct adsorptivenbsp;of S-heterocycles was investigated with the CPO-27 series. This series has a honeycomb structure in which the pores are lined with open metal sites (Ni2+, Co2+, Mg2+, Cu2+, Zn2+). It isnbsp;that the nature of the exposed open metal sites has a clear influence on the adsorption capacity and affinity, with CPO-27(Ni) having the highest affinity and capacity for all testednbsp;Computational experimentsnbsp;that this outstanding performance is due to an optimal interactionnbsp;thenbsp;nickel site and the sulfurnbsp;of the S-heterocycle. In a second strategy, the selective removal of nitrogen compounds is investigated with the mesoporous MIL-100 series. The results show a clear influence of the metal sites (V, Cr, Al, Fe) on the affinity and adsorption enthalpies for nitrogen and sulfur compounds. The availability of open metal sites and the possibility of having additional H-bond acceptor sites are importantnbsp;contributing to the observed affinity differences for the differently metallated MOFs. In a third strategy, the adsorptive removal of N/S-compounds from fuels was investigated with a fully coordinated and flexible material, namely MIL-53(Fe). By using in situ energy dispersive X-ray diffraction the influence of the solvent and adsorbate properties on the framework flexibility was studied. MIL-53(Fe) displays a remarkable uptake preference, whereby strong H-bond acceptors like benzothiophene are superior in uptake kinetics andnbsp;compared to H-bond donors like indole. In a second part, it is shown that the stablenbsp;of the MIL-140 type display exceptional performance innbsp;phenol mixtures, outperforming other material classes like zeolites, silicas, carbons and other metal-organic frameworks. By combining experimental adsorption data with computational input, it is shown that the optimal pore shape of MIL-140C allows for a convenient separationnbsp;ortho vs para-substituted phenols, due to packing effects. On the other hand, the highly hydrophobic pore surface allows for an enthalpic separation between phenols with different functional groups (like methoxy, methyl or hydroxy).nbsp;combination of enthalpic and entropic separation mechanisms results in distinct windows of separation in column breakthrough experiments withnbsp;phenol mixtures. In a final part, the mechanical properties of MOF films and powdersnbsp;investigated. First, electrochemically synthesized Cu-MOF films were characterized with a combination of nano-indentation and scratch experiments. Differences in hardness, elasticity and adhesionnbsp;of the films are found to be related to the structural differences between the Cu-MOFs. Finally, the effect of mechanical stresses during powder shaping conditions was investigated for different Zr-MOFs, as these are predicted to be amongst the more mechanically robust frameworks. An inverse relationship between framework collapse and porenbsp;was established under ball-milling conditions. Addition of acid modulators during the synthesis of UiO-66, resulted in a striking improvement of the mechanical robustness. The increased strength of Zr-carboxylate bonds is in line with the pKa values of the used modulators.nrpages: 157status: publishe

Trends in emission inventory of marine traffic for Port of Haifa

Located in the Middle East, Haifa Port serves both local and international trade interests (from Asia, Europe, America, Africa, etc.). Due to its strategic location, the port is part of the Belt and Road initiative. This research investigates Haifa Port’s emissions contribution to the existing daily emission inventory level in the area. This research is based on a developed full bottom-up model framework that looks at the single vessel daily voyage through its port call stages. The main data sources for vessel movements used in this research are the Israel Navy’s movements log and the Israel Administration of Shipping and Ports’ (ASP) operational vessel movements and cargo log. The Fuel Consumption (FC) data and Sulfur Content (SC) levels are based on official Israel ASP survey data. The observation years in this research are 2010–2018, with a focus on the Ocean-Going Vessel (OGV) type only. The results show that the vessel fleet calling at Israel ports mainly comprises vessels that have a lower engine tier grade (i.e., Tier 0 and 1), which is considered a heavy contributor to nitrogen oxide (NOx) pollution. The study recommends an additional cost charged (selective tariff) to reflect the external social cost linked to the single vessel air pollution combined with supportive technological infrastructure and economic incentive tools (e.g., electric subsidy) to attract or influence vessel owners to assign vessels equipped with new engine tier grades for calls at Israeli ports