Oxygen Reduction Reaction at Single-Site Catalysts: A Combined Electrochemical Scanning Tunnelling Microscopy and DFT Investigation on Iron Octaethylporphyrin Chloride on HOPG**

AbstractHere, we investigate the electrochemical activity of a highly oriented pyrolytic graphite (HOPG) supported iron octaethylporphyrin chloride film as a working electrode for the oxygen reduction reaction in 0.1 M HClO4 electrolyte. A voltammetric investigation indicated a quasi‐reversible electron transfer for the FeIII/FeII redox process, which turned out to be responsible for a "redox catalysis like" mechanism, in which the reduction of the metal center is first required to allow the O2 reduction. Here we proved that O2 is mostly reduced to H2O in a tetraelectronic process, as evidenced by a rotating ring‐disk electrode (RRDE). Furthermore, electrochemical scanning tunnelling microscopy (EC‐STM) is used as in operando technique for probing the electrode surface at the atomic level while the oxygen reduction reaction occurs, obtaining information on the molecule adlayer electronic and topographic structures. This allows us to follow the change in redox state from FeIII to FeII induced by the change of the electrode potential in O2 saturated electrolyte. The adsorption of O2 at the iron center was visualized and its depletion upon the application of a potential at which O2 can be reduced. The ORR process catalyzed by FeOEP adsorbed on HOPG was modelled by combining density functional theory, molecular dynamics, and thermodynamics data

Deactivation of Macrophages with Interleukin-4 Is the Key to the Isolation of Tropheryma whippelii

Whipple's disease is a systemic illness caused by a specific agent. Despite recognition of bacteria in lesions, efforts to isolate the causative agent remained futile. A novel strategy was devised to culture Whipple bacilli in deactivated mononuclear phagocytes. Infected tissue was inoculated into human phagocytes deactivated with interleukin (IL)-4, IL-10, and dexamethasone. Within 8-10 days, diastase-resistant periodic acid-Schiff-positive inclusions appeared, corresponding to intact and degenerating bacteria shown to be Tropheryma whippelii by electron microscopy and molecular analyses. T. whippelii was passaged several times in deactivated monocytes and a monoblastic cell line. Time-kinetics growth studies and comparative polymerase chain reaction analysis documented multiplication of T. whippelii in deactivated macrophages. Complementary studies showed that IL-4 rendered phagocytes permissive for T. whippelii, a strong indication that host factors contribute to the pathogenesis of Whipple's disease. The propagation of T. whippelii will permit microbiologic, immunologic, seroepidemiologic, and therapeutic studies of this pathoge

Entanglement-efficient bipartite-distributed quantum computing with entanglement-assisted packing processes

In noisy intermediate-scale quantum computing, the scalability of a quantum processor unit (QPU) is limited. The scalability of a single QPU can be extended through distributed quantum computing (DQC), in which one can implement global operations over two QPUs by entanglement-assisted local operations and classical communication (LOCC). To facilitate this type of DQC in experiments, we need an entanglement-efficient protocol. To this end, we extend the standard protocol implementing each single controlled-unitary gate with one maximally entangled pair [Eisert et. al., PRA, 62:052317(2000)] to a new protocol based on entanglement-assisted packing processes, which can implement multiple controlled-unitary gates using one maximally entangled pair. In particular, two types of packing processes are introduced as the building blocks of entanglement-efficient DQC, namely the distributing processes and embedding processes. The efficiency of entanglement is enhanced by embedding processes, which merge two non-sequential distributing processes and hence save the entanglement cost. We show that the structure of distributability and embeddability of a quantum circuit can be fully represented by packing graphs and conflict graphs. Based on these graphs, we derive heuristic algorithms for finding an entanglement-efficient packing of distributing processes for a given quantum circuit to be implemented by two parties. These algorithms can determine the required number of local auxiliary qubits in the DQC. One can also set an upper limit on the local auxiliary qubits. We apply these algorithms for bipartite DQC of unitary coupled-cluster circuits and find a significant entanglement reduction through embeddings. This method can be employed to determine a constructive upper bound on entanglement cost for a quantum circuit approaching its lower bound.Comment: 25+8 pages, 16+2 figure

Distributing circuits over heterogeneous, modular quantum computing network architectures

We consider a heterogeneous network of quantum computing modules, sparsely connected via Bell states. Operations across these connections constitute a computational bottleneck and they are likely to add more noise to the computation than operations performed within a module. We introduce several techniques for transforming a given quantum circuit into one implementable on such a network, minimising the number of Bell states required to do so. We extend previous works on circuit distribution to the case of heterogeneous networks. On the one hand, we extend the hypergraph approach of Andres-Martinez and Heunen (2019 Phys. Rev. A 100 032308) to arbitrary network topologies, and we propose the use of Steiner trees to detect and reuse common connections, further reducing the cost of entanglement sharing within the network. On the other hand, we extend the embedding techniques of Wu et al (2023 Quantum 7 1196) to networks with more than two modules. We show that, with careful manipulation of trade-offs, these two new approaches can be combined into a single automated framework. Our proposal is implemented and benchmarked; the results confirm that our contributions make noticeable improvements upon the aforementioned works and complement their weaknesses

4D Multimodal Nanomedicines Made of Nonequilibrium Au-Fe Alloy Nanoparticles

Several examples of nanosized therapeutic and imaging agents have been proposed to date, yet for most of them there is a low chance of clinical translation due to long-term in vivo retention and toxicity risks. The realization of nanoagents that can be removed from the body after use remains thus a great challenge. Here, we demonstrate that nonequilibrium gold–iron alloys behave as shape-morphing nanocrystals with the properties of self-degradable multifunctional nanomedicines. DFT calculations combined with mixing enthalpy-weighted alloying simulations predict that Au–Fe solid solutions can exhibit self-degradation in an aqueous environment if the Fe content exceeds a threshold that depends upon element topology in the nanocrystals. Exploiting a laser-assisted synthesis route, we experimentally confirm that nonequilibrium Au–Fe nanoalloys have a 4D behavior, that is, the ability to change shape, size, and structure over time, becoming ultrasmall Au-rich nanocrystals. In vivo tests show the potential of these transformable Au–Fe nanoalloys as efficient multimodal contrast agents for magnetic resonance imaging and computed X-ray absorption tomography and further demonstrate their self-degradation over time, with a significant reduction of long-term accumulation in the body, when compared to benchmark gold or iron oxide contrast agents. Hence, Au–Fe alloy nanoparticles exhibiting 4D behavior can respond to the need for safe and degradable inorganic multifunctional nanomedicines required in clinical translation.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasInstituto de Física La Plat

Role and Eective Treatment of Dispersive Forces in Materials

DFT and DFT-D calculations have been carried out on several chemical systems, ranging from molecules to crystalline polymers, bulk graphite, self-assembled phases of large molecules on metal surfaces and small molecules absorbed in porous organic-inorganic materials. Joining insights from calculations with experimental outcomes, the structural and electronic behavior of complex chemical systems have been described and explained, allowing a deeper understanding of the studied phenomena. Thanks to the implementation of a correction scheme to DFT, allowing the effective treatment of dispersion forces in materials, accurate calculations on previously unaffordable problems have been performed at a reasonable computational effort. This allowed, e.g., to understand the coverage-dependent phase transition of iron phthalocyanine on Ag(110) and the successful modeling of water absorption in a bispyrazolato copper(II) polymer.In questa tesi è presentata un'indagine computazionale basata sulla Teoria del Funzionale Densità (DFT), eseguita su un ampio range di sistemi che spazia da molecole a polimeri cristallini, grafite, fasi auto-organizzate di molecole organiche su supporti metallici e piccole molecole assorbite in materiali porosi a base organica-inorganica. Combinando le informazioni ottenute per mezzo di metodi computazionali con i risultati sperimentali, prevalentemente di microscopia a scansione ad effetto tunnel, è stato possibile descrivere il comportamento elettronico e strutturale di tali sistemi e raggiungere una compresione dettagliata del loro comportamento chimico-fisico. Grazie all'implementazione di uno schema correttivo per l'inclusione delle forze di dispersione nella DFT, sono stati effettuati calcoli accurati su sistemi altrimenti inaccessibili, pur contendo lo sforzo computazionale. Questo ha permesso, ad esempio, di capire il ruolo giocato dal ricoprimento della superficie nella transizione di fase osservata per le ftalocianine di ferro depositate su Ag(110) e di modellare con successo l'assorbimento di H20 in un polimero di Cu(II) bispirazolato

Recent Developments in Plasmonic Alloy Nanoparticles: Synthesis, Modelling, Properties and Applications

Despite the traditional plasmonic materials are counted on one hand, there are a lot of possible combinations leading to alloys with other elements of the periodic table, in particular those renowned for magnetic or catalytic properties. It is not a surprise, therefore, that nanoalloys are considered for their ability to open new perspectives in the panorama of plasmonics, representing a leading research sector nowadays. This is demonstrated by a long list of studies describing multiple applications of nanoalloys in photonics, photocatalysis, sensing and magneto-optics, where plasmons are combined with other physical and chemical phenomena. In some remarkable cases, the amplification of the conventional properties and even new effects emerged. However, this field is still in its infancy and several challenges must be overcome, starting with the synthesis (control of composition, crystalline order, size, processability, achievement of metastable phases and disordered compounds) as well as the modelling of the structure and properties (accuracy of results, reliability of structural predictions, description of disordered phases, evolution over time) of nanoalloys. To foster the research on plasmonic nanoalloys, here we provide an overview of the most recent results and developments in the field, organized according to synthetic strategies, modelling approaches, dominant properties and reported applications. Considering the several plasmonic nanoalloys under development as well as the large number of those still awaiting synthesis, modelling, properties assessment and technological exploitation, we expect a great impact on the forthcoming solutions for sustainability, ultrasensitive and accurate detection, information processing and many other fields

Physical and chemical parameters determining the formation of gold–sp metal (Al, Ga, In, and Pb) nanoalloys

Alloying is a key step towards the fabrication of advanced and unique nanomaterials demanded by the next generation of nanotechnology solutions. In particular, the alloys of Au with the sp-metals are expected to have several appealing plasmonic and electronic properties for a wide range of applications in optics, catalysis, nanomedicine, sensing and quantum devices. However, little is known about the thermodynamic and synthetic factors leading to the successful alloying of Au and sp-metals at the nanoscale. In this work, Au-M nanoalloys, with M = Al, Ga, In, or Pb, have been synthesized by a green and single step laser ablation in liquid (LAL) approach in two environments (pure ethanol and anhydrous acetone). To delve deeper into the key parameters leading to successful alloying under the typical operating conditions of LAL, a multiparametric analysis was performed considering the mixing enthalpy from DFT calculations and other alloying descriptors such as the Hume-Rothery parameters. The results showed that the dominant factors for alloying change dramatically with the oxidative ability of the synthesis environment. In this way, the tendency of the four sp metals to alloy with gold was accurately predicted (R-2 > 0.99) using only two and three parameters in anhydrous and non-anhydrous environments, respectively. These results are important to produce nanoalloys using LAL and other physical methods because they contribute to the understanding of factors leading to element mixing at the nanoscale under real synthetic conditions, which is crucial for guiding the realization of next-generation multifunctional metallic nanostructures

Histoire et civilisation du Livre

Martin Henri-Jean, Veyrin-Forrer Jeanne, Roche Daniel. Histoire et civilisation du Livre. In: École pratique des hautes études. 4e section, Sciences historiques et philologiques. Annuaire 1977-1978. 1978. pp. 885-894