Progress in the synthesis and exploitation of catenanes since the Millennium

Catenanes – molecules consisting of interlocked macrocyclic rings – have been prepared by templation strategies for some thirty years. The utilization of CuI cation, aromatic donor–acceptor interactions and hydrogen bonding assisted self-assembly strategies has led to the construction of numerous examples of these aesthetically pleasing species. This review seeks to discuss key developments in the synthesis and functional application of catenanes that have occurred since the Millennium. The much expanded range of metal cation templates; the genesis and growth of anion templation, as well as the use of alternative supramolecular interactions (halogen bonding and radical templation) and thermodynamically controlled reactions to synthesize catenanes are detailed. The class of catenanes that may be described as “molecular machines” are then highlighted and to conclude, attempts to fabricate catenanes onto surfaces and into metal organic frameworks (MOFs) are discussed

Advances in anion supramolecular chemistry:from recognition to chemical applications

Since the start of this millennium, remarkable progress in the binding and sensing of anions has been taking place, driven in part by discoveries in the use of hydrogen bonding, as well as the previously under-exploited anion–π interactions and halogen bonding. However, anion supramolecular chemistry has developed substantially beyond anion recognition, and now encompasses a diverse range of disciplines. Dramatic advance has been made in the anion-templated synthesis of macrocycles and interlocked molecular architectures, while the study of transmembrane anion transporters has flourished from almost nothing into a rapidly maturing field of research. The supramolecular chemistry of anions has also found real practical use in a variety of applications such as catalysis, ion extraction, and the use of anions as stimuli for responsive chemical systems

What Shall We Call God? An Exploration of Metaphors Coded From Descriptions of God From A Large U.S. Undergraduate Sample

People use numerous metaphors to describe God. God is seen as a bearded man, light, and love. Based on metaphor theories, the metaphors people use to refer to God reflect how people think about God and could, in turn, reflect their worldview. However, little work has explored the common metaphors for God. This was the purpose of the current investigation. Four trained raters coded open-ended responses from predominantly Christian U.S. undergraduates (N = 2,923) describing God for the presence or absence of numerous metaphoric categories. We then assessed the frequency of each of the metaphor categories. We identified 16 metaphor categories that were present in more than 1% of the responses. The top categories were “GOD IS POWER,” “GOD IS HUMAN,” and “GOD IS MALE.” These findings were similar across religious affiliations. We attempted to support our coding analysis using top-down and bottom-up automated language analysis. Results from these analyses provided added confidence to our conclusions. We discuss the implications of our findings and the potential for future studies investigating important psychological and behavioral outcomes of using different metaphors for God

Epithelial mechanobiology, skin wound healing, and the stem cell niche

AbstractSkin wound healing is a vital process that is important for re-establishing the epithelial barrier following disease or injury. Aberrant or delayed skin wound healing increases the risk of infection, causes patient morbidity, and may lead to the formation of scar tissue. One of the most important events in wound healing is coverage of the wound with a new epithelial layer. This occurs when keratinocytes at the wound periphery divide and migrate to re-populate the wound bed. Many approaches are under investigation to promote and expedite this process, including the topical application of growth factors and the addition of autologous and allogeneic tissue or cell grafts. The mechanical environment of the wound site is also of fundamental importance for the rate and quality of wound healing. It is known that mechanical stress can influence wound healing by affecting the behaviour of cells within the dermis, but it remains unclear how mechanical forces affect the healing epidermis. Tensile forces are known to affect the behaviour of cells within epithelia, however, and the material properties of extracellular matrices, such as substrate stiffness, have been shown to affect the morphology, proliferation, differentiation and migration of many different cell types. In this review we will introduce the structure of the skin and the process of wound healing. We will then discuss the evidence for the effect of tissue mechanics in re-epithelialisation and, in particular, on stem cell behaviour in the wound microenvironment and in intact skin. We will discuss how the elasticity, mechanical heterogeneity and topography of the wound extracellular matrix impact the rate and quality of wound healing, and how we may exploit this knowledge to expedite wound healing and mitigate scarring

The determination of the structure of Saturn's F ring by nearby moonlets

International audienceSaturn's narrow F ring exhibits several unusual features that vary on timescales of hours to years. These include transient clumps, a central core surrounded by a multistranded structure and a regular series of longitudinal channels associated with Prometheus, one of the ring's two 'shepherding' satellites. Several smaller moonlets and clumps have been detected in the ring's immediate vicinity, and a population of embedded objects has been inferred. Here we report direct evidence of moonlets embedded in the ring's bright core, and show that most of the F ring's morphology results from the continual gravitational and collisional effects of small satellites, often combined with the perturbing effect of Prometheus. The F-ring region is perhaps the only location in the Solar System where large-scale collisional processes are occurring on an almost daily basis

New insights into hierarchical clustering and linguistic normalization for speaker diarization

Face au volume croissant de données audio et multimédia, les technologies liées à l'indexation de données et à l'analyse de contenu ont suscité beaucoup d'intérêt dans la communauté scientifique. Parmi celles-ci, la segmentation et le regroupement en locuteurs, répondant ainsi à la question 'Qui parle quand ?' a émergé comme une technique de pointe dans la communauté de traitement de la parole. D'importants progrès ont été réalisés dans le domaine ces dernières années principalement menés par les évaluations internationales du NIST. Tout au long de ces évaluations, deux approches se sont démarquées : l'une est bottom-up et l'autre top-down. L'ensemble des systèmes les plus performants ces dernières années furent essentiellement des systèmes types bottom-up, cependant nous expliquons dans cette thèse que l'approche top-down comporte elle aussi certains avantages. En effet, dans un premier temps, nous montrons qu'après avoir introduit une nouvelle composante de purification des clusters dans l'approche top-down, nous obtenons des performances comparables à celles de l'approche bottom-up. De plus, en étudiant en détails les deux types d'approches nous montrons que celles-ci se comportent différemment face à la discrimination des locuteurs et la robustesse face à la composante lexicale. Ces différences sont alors exploitées au travers d'un nouveau système combinant les deux approches. Enfin, nous présentons une nouvelle technologie capable de limiter l'influence de la composante lexicale, source potentielle d'artefacts dans le regroupement et la segmentation en locuteurs. Notre nouvelle approche se nomme Phone Adaptive Training par analogie au Speaker Adaptive TrainingThe ever-expanding volume of available audio and multimedia data has elevated technologies related to content indexing and structuring to the forefront of research. Speaker diarization, commonly referred to as the who spoke when?' task, is one such example and has emerged as a prominent, core enabling technology in the wider speech processing research community. Speaker diarization involves the detection of speaker turns within an audio document (segmentation) and the grouping together of all same-speaker segments (clustering). Much progress has been made in the field over recent years partly spearheaded by the NIST Rich Transcription evaluations focus on meeting domain, in the proceedings of which are found two general approaches: top-down and bottom-up. Even though the best performing systems over recent years have all been bottom-up approaches we show in this thesis that the top-down approach is not without significant merit. Indeed we first introduce a new purification component leading to competitive performance to the bottom-up approach. Moreover, while investigating the two diarization approaches more thoroughly we show that they behave differently in discriminating between individual speakers and in normalizing unwanted acoustic variation, i.e.\ that which does not pertain to different speakers. This difference of behaviours leads to a new top-down/bottom-up system combination outperforming the respective baseline system. Finally, we introduce a new technology able to limit the influence of linguistic effects, responsible for biasing the convergence of the diarization system. Our novel approach is referred to as Phone Adaptive Training (PAT).PARIS-Télécom ParisTech (751132302) / SudocSudocFranceF

Microrheology with optical tweezers: data analysis

We present a data analysis procedure that provides the solution to a long-standing issue in microrheology studies, i.e. the evaluation of the fluids' linear viscoelastic properties from the analysis of a finite set of experimental data, describing (for instance) the time-dependent mean-square displacement of suspended probe particles experiencing Brownian fluctuations. We report, for the first time in the literature, the linear viscoelastic response of an optically trapped bead suspended in a Newtonian fluid, over the entire range of experimentally accessible frequencies. The general validity of the proposed method makes it transferable to the majority of microrheology and rheology techniques

Combinatorial Delivery of Bioactive Molecules by a Nanoparticle-Decorated and Functionalized Biodegradable Scaffold

The combination of supportive biomaterials and bioactive factors to stimulate endogenous progenitor cells is of key interest for the treatment of conditions in which intrinsic bone healing capacities are compromised. To address this need a “scaffold-decoration platform” was developed in which a biocompatible, biotin-functionalised 3D structural polymer network was generated through a solvent blending process, and used to recruit avidin modified nanoparticles within its 3D structure through biotin-avidin conjugation. This was enabled via the generation of a suite of poly(lactic-co-glycolic acid) (PLGA) nanoparticles, encapsulating two bioactive factors, vascular endothelial growth factor (VEGF) and L-Ascorbic acid 2-phosphate (AA2P) and conjugated to streptavidin to allow attachment to the bone generating scaffold. The levels of encapsulated and released VEGF and AA2P were tailored to fall within the desired range to promote biological activity as confirmed by an increase in endothelial cell tubule formation and collagen production by osteoblast cells in response to nanoparticle release of VEGF and AA2P, respectively. The release of VEGF from the scaffolds produced a significant effect on vasculature development within the chick chorioallantoic membrane (CAM) angiogenic assay. Similarly, the scaffolds showed strong biological effects in ex vivo assays indicating the potential of this platform for localised delivery of bioactive molecules with applications in both hard and soft tissue engineering