Hydrophobic Hydration of the Hydrocarbon Adamantane in Amorphous Ice

Hydrophobic molecules are by definition difficult to hydrate. Previous studies in the area of hydrophobic hydration have therefore often relied on using amphiphilic molecules where the hydrophilic part of a molecule enabled the solubility in liquid water. Here we show that the hydrophobic adamantane (C10H16) molecule can be fully hydrated through vapour codeposition with water onto a cryogenic substrate at 80 K resulting in the matrix isolation of adamantane in amorphous ice. Using neutron diffraction in combination with the isotopic substitution method and the empirical potential structure refinement technique, we find that the first hydration shell of adamantane is well structured consisting of a hydrogen-bonded cage of 28 water molecules that is also found in cubic structure II clathrate hydrates. The four hexagonal faces of the 51264 cage are situated above the four methine (CH) groups of adamantane whereas the methylene (CH2) groups are positioned below the edges of two adjoining pentagonal faces. The oxygen atoms of the 28 water molecules can be categorised on the basis of symmetry equivalences as twelve A, twelve B and four C oxygens. The water molecules of the first hydration shell display orientations consistent with those expected for a clathrate-hydrate-type cage, but also unfavourable ones with respect to the hydrogen bonding between the water molecules. Annealing the samples at 140 K, which is just below the crystallisation temperature of the matrix, removes the unfavourable orientations and leads to a slight increase of the structural order of the first hydration shell. The very closest water molecules display a tendency for their dipole moments to point towards the adamantane which is attributed to steric effects. Other than this, no significant polarisation effects are observed which is consistent with weak interactions between adamantane and the amorphous ice matrix. FT-IR spectroscopy shows that the incorporation of adamantane into amorphous ice leads to a weakening of the hydrogen bonds. In summary, the matrix-isolation of the highly symmetric adamantane in amorphous ice provides an interesting test case for hydrophobic hydration. Studying the structure and spectroscopic properties of water at the interface with hydrophobic hydrocarbons is also relevant for astrophysical environments, such as comets or the interstellar medium, where amorphous ice and hydrocarbons have been shown to coexist in large quantities

Hydrophobic hydration of the hydrocarbon adamantane in amorphous ice

The hydrophobic adamantane molecule is fully hydrated through vapour codeposition with water onto a cryogenic substrate and the structure of the first hydration shell is studied with neutron diffraction.Peer ReviewedPostprint (published version

Graphene Nanoflake Antibody Conjugates for Multimodal Imaging of Tumors

Graphene-based materials are promising scaffolds for use in the design of tailored-made nanomedicines. Herein, the synthesis and characterization of a series of multifunctional carboxylated graphene nanoflakes (GNFs) conjugated to monoclonal antibodies (mAbs) for tumor-specific binding and modulation of pharmacokinetics is presented. GNF–mAb constructs are coupled to a fluorophore (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene [BODIPY]) for applications in optical imaging, a paramagnetic Gd3+ complex, [GdDOTAGA(H2O)]−, and the hexadentate chelate desferrioxamine B (DFO) for radiolabeling with 89Zr4+ (t1/2 = 78.41 h) ions and applications in dual-modality positron emission tomography/magnetic resonance imaging (PET/MRI). Experimental properties of [89Zr]GdDOTAGA–ZrDFO–GNF–trastuzumab are tested in extensive chemical, spectroscopic, radiochemical, and cellular assays in vitro, and assessment of the pharmacokinetics by PET imaging in mice bearing a human ovarian cancer model illustrates the potential of using GNF–mAbs to develop multifunctional PET/MRI probes

Amorphous Mixtures of Ice and C60 Fullerene

Carbon and ice make up a substantial proportion of our Universe. Recent space exploration has shown that these two chemical species often coexist including on comets, asteroids and in the interstellar medium. Here we prepare mixtures of C60 fullerene and H2O by vapor co-deposition at 90 K with molar C60:H2O ratios ranging from 1:1254 to 1:5. The C60 percolation threshold is found between the 1:132 and 1:48 samples, corresponding to a transition from matrix-isolated C60 molecules to percolating C60 domains that confine the H2O. Below this threshold, the crystallization and thermal desorption properties of H2O are not significantly affected by the C60, whereas the crystallization temperature of H2O is shifted towards higher temperatures for the C60-rich samples. These C60-rich samples also display exotherms corresponding to the crystallization of C60 as the two components undergo phase separation. More than 60 volume percent C60 is required to significantly affect the desorption properties of H2O. A thick blanket of C60 on top of pure amorphous ice is found to display large cracks due to water desorption. These findings may help understand the recently observed unusual surface features and the H2O weather cycle on the 67P/Churyumov–Gerasimenko comet

Amorphous Mixtures of Ice and C60 Fullerene

Carbon and ice make up a substantial proportion of our Universe. Recent space exploration has shown that these two chemical species often coexist including on comets, asteroids and in the interstellar medium. Here we prepare mixtures of C60 fullerene and H2O by vapor co-deposition at 90 K with molar C60:H2O ratios ranging from 1:1254 to 1:5. The C60 percolation threshold is found between the 1:132 and 1:48 samples, corresponding to a transition from matrix-isolated C60 molecules to percolating C60 domains that confine the H2O. Below this threshold, the crystallization and thermal desorption properties of H2O are not significantly affected by the C60, whereas the crystallization temperature of H2O is shifted towards higher temperatures for the C60-rich samples. These C60-rich samples also display exotherms corresponding to the crystallization of C60 as the two components undergo phase separation. More than 60 volume percent C60 is required to significantly affect the desorption properties of H2O. A thick blanket of C60 on top of pure amorphous ice is found to display large cracks due to water desorption. These findings may help understand the recently observed unusual surface features and the H2O weather cycle on the 67P/Churyumov-Gerasimenko comet

Lessons Learned from Co-Evolution of Software Process and Model-Driven Engineering

Software companies need to cope with permanent changes in market. To stay competitive it is often inevitable to improve processes and adopt to new technologies. Indeed, it is well know that software processes and model-driven engineering (MDE) are subject to evolution. Simultaneously, it is known that MDE can affect process tailoring, which makes it possible that evolution in MDE triggers process evolution and vice versa. This can lead to undesired process changes and additional cost, when process adaptations constitute a need for further investments in MDE tooling. However, there is little knowledge so far whether this co-evolution exists and how it looks like. In this chapter, we present two industrial case studies onco-evolution of MDE and software process. Based on these case studies, we present an initial list of co-evolution drivers and observations made on co-evolution of softwareprocesses and MDE. Furthermore, we compile our lessons learned to directly help process managers dealing with co-evolution