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"Pérez, Daniel"
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Random Access Memory (RAM) Contacts Waste Catalyzes Organic Reactions
The direct utilization of metals from electronic waste (e‐waste) in catalysis is a barely explored concept that, however, should be feasible for reactions where the catalytically active species can be formed in situ from the e‐waste metal pieces. This approach circumvents any capture or isolation of particular metals, thus saving additional treatments (extractions, neutralization, separations, washings, …) and valorizing the e‐waste in its own. Here, it is shown that a metallic contact (≈1 mg) of a computer´s random‐access memory (RAM) catalyzes a variety of organic reactions in high yields. For instance, one RAM contact catalyzes the one‐pot esterification‐hydration reaction between acyl chlorides, propargyl alcohols, and water, at room temperature in 93–99% yields with turnover frequencies >0.5 million per hour. In this way, >50 kg of organic products could be prepared with just the RAM contacts discarded per year in the Institute´s recycling bin. These results open the way to directly use e‐waste in catalysis for organic synthesis.
Wasted RAM contacts catalyze different organic reactions in good to excellent yields, with turnover numbers >0.5 million in some cases. The RAM contacts are used without any previous treatment and are recovered and reused. Kilograms of organic products could be produced with the RAM contacts of just five discarded laptops. These results open the way to use directly e‐waste in catalysis for organic synthesis.
Journal Article
Macbeth
A graphic novel adaptation of William Shakespeare's play about Macbeth, the eleventh-century king of Scotland, and of the tragedy of prophecy and royal murder.
BOOK
Differential Contribution of PB1-F2 to the Virulence of Highly Pathogenic H5N1 Influenza A Virus in Mammalian and Avian Species
Highly pathogenic avian influenza A viruses (HPAIV) of the H5N1 subtype occasionally transmit from birds to humans and can cause severe systemic infections in both hosts. PB1-F2 is an alternative translation product of the viral PB1 segment that was initially characterized as a pro-apoptotic mitochondrial viral pathogenicity factor. A full-length PB1-F2 has been present in all human influenza pandemic virus isolates of the 20(th) century, but appears to be lost evolutionarily over time as the new virus establishes itself and circulates in the human host. In contrast, the open reading frame (ORF) for PB1-F2 is exceptionally well-conserved in avian influenza virus isolates. Here we perform a comparative study to show for the first time that PB1-F2 is a pathogenicity determinant for HPAIV (A/Viet Nam/1203/2004, VN1203 (H5N1)) in both mammals and birds. In a mammalian host, the rare N66S polymorphism in PB1-F2 that was previously described to be associated with high lethality of the 1918 influenza A virus showed increased replication and virulence of a recombinant VN1203 H5N1 virus, while deletion of the entire PB1-F2 ORF had negligible effects. Interestingly, the N66S substituted virus efficiently invades the CNS and replicates in the brain of Mx+/+ mice. In ducks deletion of PB1-F2 clearly resulted in delayed onset of clinical symptoms and systemic spreading of virus, while variations at position 66 played only a minor role in pathogenesis. These data implicate PB1-F2 as an important pathogenicity factor in ducks independent of sequence variations at position 66. Our data could explain why PB1-F2 is conserved in avian influenza virus isolates and only impacts pathogenicity in mammals when containing certain amino acid motifs such as the rare N66S polymorphism.
Journal Article
Multipurpose self-configuration of programmable photonic circuits
Programmable integrated photonic circuits have been called upon to lead a new revolution in information systems by teaming up with high speed digital electronics and in this way, adding unique complementary features supported by their ability to provide bandwidth-unconstrained analog signal processing. Relying on a common hardware implemented by two-dimensional integrated photonic waveguide meshes, they can provide multiple functionalities by suitable programming of their control signals. Scalability, which is essential for increasing functional complexity and integration density, is currently limited by the need to precisely control and configure several hundreds of variables and simultaneously manage multiple configuration actions. Here we propose and experimentally demonstrate two different approaches towards management automation in programmable integrated photonic circuits. These enable the simultaneous handling of circuit self-characterization, auto-routing, self-configuration and optimization. By combining computational optimization and photonics, this work takes an important step towards the realization of high-density and complex integrated programmable photonics.
Signal processors based on programmable photonic circuits will enable many future applications employing a common hardware platform. The authors present the architecture and two approaches to management automation to enable self-configuration and optimization of such photonic integrated circuits.
Journal Article
General-purpose programmable photonic processor for advanced radiofrequency applications
A general-purpose photonic processor can be built integrating a silicon photonic programmable core in a technology stack comprising an electronic monitoring and controlling layer and a software layer for resource control and programming. This processor can leverage the unique properties of photonics in terms of ultra-high bandwidth, high-speed operation, and low power consumption while operating in a complementary and synergistic way with electronic processors. These features are key in applications such as next-generation 5/6 G wireless systems where reconfigurable filtering, frequency conversion, arbitrary waveform generation, and beamforming are currently provided by microwave photonic subsystems that cannot be scaled down. Here we report the first general-purpose programmable processor with the remarkable capability to implement all the required basic functionalities of a microwave photonic system by suitable programming of its resources. The processor is fabricated in silicon photonics and incorporates the full photonic/electronic and software stack.
The authors report implementing and demonstrating a first general-purpose integrated photonic programmable processor capable of performing all the functionalities required in RF photonic systems, such as those needed in 5/6 G communications networks.
Journal Article
Neuropathy of haematopoietic stem cell niche is essential for myeloproliferative neoplasms
Myeloproliferative neoplasms are caused by mutations in the haematopoietic stem cell (HSC) compartment, and here the authors show that the HSC niche contributes to the pathogenesis; sympathetic innervation of mesenchymal stem cells (MSCs) is reduced in the bone marrow of patients, which leads to reduced MSC numbers and increased mutant HSC expansion, and restoring sympathetic regulation of MSCs with neuroprotective/sympathomimetic drugs prevents mutant HSC expansion.
Pathogenesis of myeloproliferative neoplasms
The stem cell niche has recently been recognized as an oncogenic unit and an important element in regulating cancer stem cells. Here, Simón Méndez-Ferrer and colleagues demonstrate that sympathetic innervation of nestin-positive mesenchymal stem cells (MSCs) in the bone marrow microenvironment is reduced in patients with myeloproliferative neoplasms. This denervation leads to reduced MSC numbers and increased mutant haematopoietic stem cell (HSC) expansion. When sympathetic regulation of nestin-positive MSCs is restored by neuroprotective drugs, mutant HSC expansion is prevented.
Myeloproliferative neoplasms (MPNs) are diseases caused by mutations in the haematopoietic stem cell (HSC) compartment. Most MPN patients have a common acquired mutation of Janus kinase 2 (
JAK2
) gene in HSCs
1
,
2
,
3
,
4
that renders this kinase constitutively active, leading to uncontrolled cell expansion. The bone marrow microenvironment might contribute to the clinical outcomes of this common event. We previously showed that bone marrow nestin
+
mesenchymal stem cells (MSCs) innervated by sympathetic nerve fibres regulate normal HSCs
5
,
6
. Here we demonstrate that abrogation of this regulatory circuit is essential for MPN pathogenesis. Sympathetic nerve fibres, supporting Schwann cells and nestin
+
MSCs are consistently reduced in the bone marrow of MPN patients and mice expressing the human
JAK2(V617F)
mutation in HSCs. Unexpectedly, MSC reduction is not due to differentiation but is caused by bone marrow neural damage and Schwann cell death triggered by interleukin-1β produced by mutant HSCs. In turn,
in vivo
depletion of nestin
+
cells or their production of CXCL12 expanded mutant HSC number and accelerated MPN progression. In contrast, administration of neuroprotective or sympathomimetic drugs prevented mutant HSC expansion. Treatment with β
3
-adrenergic agonists that restored the sympathetic regulation of nestin
+
MSCs
5
,
6
prevented the loss of these cells and blocked MPN progression by indirectly reducing the number of leukaemic stem cells. Our results demonstrate that mutant-HSC-driven niche damage critically contributes to disease manifestation in MPN and identify niche-forming MSCs and their neural regulation as promising therapeutic targets.
Journal Article
Plant community responses to stand-level nutrient fertilization in a secondary tropical dry forest
The size of the terrestrial carbon (C) sink is mediated by the availability of nutrients that limit plant growth. However, nutrient controls on primary productivity are poorly understood in the geographically extensive yet understudied tropical dry forest biome. To examine how nutrients influence above- and belowground biomass production in a secondary, seasonally dry tropical forest, we conducted a replicated, fully factorial nitrogen (N) and phosphorus (P) fertilization experiment at the stand scale in Guanacaste, Costa Rica. The production of leaves, wood, and fine roots was monitored through time; root colonization by mycorrhizal fungi and the abundance of N-fixing root nodules were also quantified. In this seasonal forest, interannual variation in rainfall had the largest influence on stand-level productivity, with lower biomass growth under drought. By contrast, aboveground productivity was generally not increased by nutrient addition, although fertilization enhanced growth of individual tree stems in a wet year. However, root growth increased markedly and consistently under P addition, significantly altering patterns of stand-level biomass allocation to above- vs. belowground compartments. Although nutrients did not stimulate total biomass production at the community scale, N-fixing legumes exhibited a twofold increase in woody growth in response to added P, accompanied by a dramatic increase in the abundance of root nodules. These data suggest that the relationship between nutrient availability and primary production in tropical dry forest is contingent on both water availability and plant functional diversity.
Journal Article
Silicon Nitride Photonic Integration Platforms for Visible, Near-Infrared and Mid-Infrared Applications
Silicon nitride photonics is on the rise owing to the broadband nature of the material, allowing applications of biophotonics, tele/datacom, optical signal processing and sensing, from visible, through near to mid-infrared wavelengths. In this paper, a review of the state of the art of silicon nitride strip waveguide platforms is provided, alongside the experimental results on the development of a versatile 300 nm guiding film height silicon nitride platform.
Journal Article