Accessing Extended Fused Isoindolinones Via Sequential Anionic Intramolecular Cyclizations

Sequential anionic intramolecular cyclizations and modelling were used for the first time to access unusual fused heterocyclic frameworks in excellent yields. 5-Exo-dig cyclizations yielded isoindolinone motifs and a subsequent 6-exo- and 7-endo-dig cyclization was directed to provide either fused isoquinoline or azepine frameworks. Regioselectivities were controlled by exploiting stereoelectronic effects via n_C−→π*_(Ph) interactions, and modelling studies provided reaction scope.     

In-situ surface-sensitive X-ray diffraction study on the influence of iodide over the selective electrochemical etching of Cu3Au (111)

During selective etching (dealloying) surface-sensitive X-ray diffraction employing Synchrotron light has been used to in-situ monitor the potential-controlled formation of Au-rich films on the surface of Cu₃Au (111) in iodide-containing electrolytes. Similar to the case in pure sulfuric acid we observed a sequence of structural transformations starting from a well-prepared pristine surface to a porous film consisting of substrate-oriented Au ligaments. Also stacking-reversed ultrathin Au-rich films and Au islands form as intermediate steps but no passive-like behavior was observed in iodide-containing electrolytes, i.e. the surface quickly developed Au ligaments after reaching the Cu dissolution potential. At low overpotentials comparatively coarse Au islands point to a higher mobility of Au/electrolyte interfaces in iodide-containing solutions. At higher overpotentials and also with higher iodide concentrations an epitaxial Cu-iodide precipitate film showed an orientation relation of CuI (111) || CuAu (111) and two azimuthal domains of < ? 2, 2, 0 > || < ? 2, 2, 0 > and < ? 2, 2, 0 > || < 2, ? 2, 0>. This partially dissolution-inhibiting bulk CuI layer is observed to produce a bimodal pore size instead of usually obtained homogeneous porosity. The X-ray data and supporting ex-situ AFM and SEM images show marked differences in the morphology and connectivity of the forming nanoporous Au layer. Precipitation layers are thus suggested to provide means for controlling the nanoporosity for applications of dealloyed films and surfaces.     

Slumping Flows in Narrow Eccentric Annuli: Design of Chemical Packers and Cementing of Subsurface Gas Pipelines

In well construction, there are an increasing number of scenarios in which plugs are being set in annular geometries, whether as cement plugs or simply in the form of chemical packers. The generic reason for setting of such plugs is to hydraulically isolate different regions of a wellbore (or hole). An interesting practical problem in such situations is to predict the rheological properties that are necessary to prevent the annular plug fluid from flowing under the action of buoyancy, or indeed to predict how far the plug material may flow for given rheological properties. The answers to these questions provide valuable information for operational design. Mathematically, these flows are modeled using a Hele-Shaw style approximation of the narrow annulus. Since fluids used in the wellbore are non-Newtonian, typically shear-thinning and with a yield stress, the relationship between the local modified pressure gradient and the gap-averaged velocity field is nonlinear. If the yield stress of the fluids is sufficiently large, relative to the applied pressure over the gap, there is no flow. In the porous media context, there is direct analogy with problems of nonlinear seepage and in particular with non-Darcy flows with limiting pressure gradient. The study of such flows was both pioneered and developed by V.M. Entov, to whose memory this paper is dedicated.     

Combined phase-sensitive acoustic microscopy and confocal laser scanning microscopy

Combined phase-sensitive acoustic microscopy (PSAM) at 1.2 GHz and confocal laser scanning microscopy (CLSM) in reflection and fluorescence has been implemented and applied to polymer blend films and fluorescently labeled fibroblasts and neuronal cells in order to explore the prospects and the various contrast mechanisms of this powerful technique. Topographic contrast is available for appropriate samples from CLSM in reflection and, with significantly higher precision, from the acoustic phase images. Material contrast can be gained from acoustic amplitude V(z) graphs. In the case of the biological cells investigated, the optical and acoustic images are very different and exhibit different features of the samples.     

Initiation and inhibition of dealloying of single crystalline Cu3Au (111) surfaces

Dealloying is widely utilized but is a dangerous corrosion process as well. Here we report an atomistic picture of the initial stages of electrochemical dealloying of the model system Cu(3)Au (111). We illuminate the structural and chemical changes during the early stages of dissolution up to the critical potential, using a unique combination of advanced surface-analytical tools. Scanning tunneling microscopy images indicate an interlayer exchange of topmost surface atoms during initial dealloying, while scanning Auger-electron microscopy data clearly reveal that the surface is fully covered by a continuous Au-rich layer at an early stage. Initiating below this first layer a transformation from stacking-reversed toward substrate-oriented Au surface structures is observed close to the critical potential. We further use the observed structural transitions as a reference process to evaluate the mechanistic changes induced by a thiol-based model-inhibition layer applied to suppress surface diffusion. The initial ultrathin Au layer is stabilized with the intermediate island morphology completely suppressed, along an anodic shift of the breakdown potential. Thiol-modification induces a peculiar surface microstructure in the form of microcracks exhibiting a nanoporous core. On the basis of the presented atomic-scale observations, an interlayer exchange mechanism next to pure surface diffusion becomes obvious which may be controlling the layer thickness and its later change in orientation.     

A model of fluid injection into the spinal disc

This paper presents an analytical model of the stress–strain response of intervertebral disc to fluid injection. The disc has nonlinear properties and collagen fibres play a significant role in sustaining strain. Each fibre is modeled as a flexible, helical string inclined at ∼30° to the horizontal plane. The tensile stress in the fibres is obtained from a nonlinear stress–strain law that has been determined by experiment. An asymptotic approximation of the model equations based on the ratio of the fluid injected to the initial volume of fluid in the disc is developed and its solution obtained. Some quantitative predictions are made by considering a hypothetical value of the amount of fluid injected and some material values of discs at different levels of the spine. Numerical simulations show that the model compare reasonably well with some experimental observations for discs of the lumbar region.     

The Therapeutic Potential of Psilocybin

The psychedelic effects of some plants and fungi have been known and deliberately exploited by humans for thousands of years. Fungi, particularly mushrooms, are the principal source of naturally occurring psychedelics. The mushroom extract, psilocybin has historically been used as a psychedelic agent for religious and spiritual ceremonies, as well as a therapeutic option for neuropsychiatric conditions. Psychedelic use was largely associated with the “hippie” counterculture movement, which, in turn, resulted in a growing, and still lingering, negative stigmatization for psychedelics. As a result, in 1970, the U.S. government rescheduled psychedelics as Schedule 1 drugs, ultimately ending scientific research on psychedelics. This prohibition on psychedelic drug research significantly delayed advances in medical knowledge on the therapeutic uses of agents such as psilocybin. A 2004 pilot study from the University of California, Los Angeles, exploring the potential of psilocybin treatment in patients with advanced-stage cancer managed to reignite interest and significantly renewed efforts in psilocybin research, heralding a new age in exploration for psychedelic therapy. Since then, significant advances have been made in characterizing the chemical properties of psilocybin as well as its therapeutic uses. This review will explore the potential of psilocybin in the treatment of neuropsychiatry-related conditions, examining recent advances as well as current research. This is not a systematic review.     

Mathematical assessment of the role of non-linear birth and maturation delay in the population dynamics of the malaria vector

A delay ordinary deterministic differential equation model for the population dynamics of the malaria vector is rigorously analysed subject to two forms of the vector birth rate function: the Verhulst-Pearl logistic growth function and the Maynard-Smith-Slatkin function. It is shown that, for any birth rate function satisfying some assumptions, the trivial equilibrium of the model is globally-asymptotically stable if the associated vectorial reproduction number is less than unity. Further, the model has a non-trivial equilibrium which is locally-asymptotically stable under a certain condition. The non-trivial equilibrium bifurcates into a limit cycle via a Hopf bifurcation. It is shown, by numerical simulations, that the amplitude of oscillating solutions increases with increasing maturation delay. Numerical simulations suggest that the Maynard-Smith-Slatkin function is more suitable for modelling the vector population dynamics than the Verhulst-Pearl logistic growth model, since the former is associated with increased sustained oscillations, which (in our view) is a desirable ecological feature, since it guarantees the persistence of the vector in the ecosystem.     

Phase-sensitive acoustic microscopy of polymer thin films

The three-dimensional images obtained by scanning acoustic microscopy with vector contrast (PSAM), contain significant qualitative and quantitative information that is not easily obtainable by other methods. We employ this technique to examine homopolymer and polymer blend thin films. The complex V(z) functions derived from the images, and the results obtained by image processing and meticulous analysis are employed to render the morphology, composition and micro-mechanical properties of the polymer films. In addition, ways by which the information inherent in the phase images can be extracted are examined. This is highly desirable, as the phase images contain very useful additional information.