Dissipative stabilization of dark quantum dimers via squeezed vacuum

Understanding the mechanism through which an open quantum system exchanges information with an environment is central to the creation and stabilization of quantum states. This theme has been explored recently, with attention mostly focused on system control or environment engineering. Here, we bring these ideas together to describe the many-body dynamics of an extended atomic array coupled to a squeezed vacuum. We show that fluctuations can drive the array into a pure dark state decoupled from the environment. The dark state is obtained for an even number of atoms and consists of maximally entangled atomic pairs, or dimers, that mimic the behavior of the squeezed field. Each pair displays reduced fluctuations in one polarization quadrature and amplified in another. This dissipation-induced stabilization relies on an efficient transfer of correlations between pairs of photons and atoms. It uncovers the mechanism through which squeezed light causes an atomic array to self-organize and illustrates the increasing importance of spatial correlations in modern quantum technologies where many-body effects play a central role

Effect of antimony on the eutectic reaction of heavy section spheroidal graphite castings

There is a strong demand for heavy section castings made of spheroidal graphite with a fully ferritic matrix, e.g. for manufacturing hubs for windmills. Such castings with slow solidification process are prone to graphite degeneration that leads to a dramatic decrease of the mechanical properties of the cast parts. Chunky graphite is certainly the most difficult case of graphite degeneracy, though it has long been known that the limited and controlled addition of antimony may help eliminate it. The drawback of this remedy is that too large Sb additions lead to other forms of degenerate graphite, and also that antimony is a pearlite promoter. As part of an investigation aimed at mastering low level additions to cast iron melts before casting, solidification of large blocks with or without Sb added was followed by thermal analysis. Comparison of the cooling curves and of the microstructures of these different castings gives suggestions to understand the controlling nucleation and growth mechanisms for chunky graphite cells

Effect of Antimony and Cerium on the Formation of Chunky Graphite during Solidification of Heavy-Section Castings of Near-Eutectic Spheroidal Graphite Irons

Thermal analysis is applied to the study of the formation of chunky graphite (CHG) in heavysection castings of spheroidal graphite cast irons. To that aim, near-eutectic melts prepared in one single cast house were poured into molds containing up to four large cubic blocks 30 cm in size. Four melts have been prepared and cast that had a cerium content varying in relation with the spheroidizing alloy used. Postinoculation or addition of antimony was achieved by fixing appropriate amounts of materials in the gating system of each block. Cooling curves recorded in the center of the blocks show that solidification proceeds in three steps: a short primary deposition of graphite followed by an initial and then a bulk eutectic reaction. Formation of CHG could be unambiguously associated with increased recalescence during the bulk eutectic reaction. While antimony strongly decreases the amount of CHG, it appears that the ratio of the contents in antimony and cerium should be higher than 0.8 in order to avoid this graphite degeneracy

Synthesis and morphological characterization of nanocomposite based on anodic TiO2 nanotubes and poly(N-maleoyl Glycine-CO-Acrylic acid)

Indexación: Scopus.In this study, we examined the synthesis, and characterization of TiO2/poly(N-maleoylglycine-co-acrylic acid) (TiO2/poly(MG-co-AA)) nanocomposite. The nanocomposite was prepared by the dispersion of TiO2 nanotubes in a water solution of the polymer (3% w/w) and then it was lyophilized. The nanocomposite was characterized by FTIR and Raman spectroscopies. The incorporation of TiO2 nanotubes to the polymeric matrix was determined by transmission electron microscopy (TEM) from which TiO2 nanotubes in the inner of copolymer with diameters ranging between 90 and 100 nm were observed. The overall morphology of the previously synthetized nanotubes was determined by scanning electron microscopy (SEM). For the nanocomposite system, the morphology was studied by atomic force microscopy (AFM) from which a grain shape structure was observed. This process resulted in a new nanocompsite material with an average grain diameter estimated by SEM and AFM ranging between 210-240 nm. It was observed that the nanotubes were homogeneously dispersed within the polymeric matrix. The prepared material could be suitable in the design of electronic devices and additionally could have potential applications as biomaterial.https://scielo.conicyt.cl/pdf/jcchems/v62n3/0717-9324-jcchems-62-03-3634.pd

Lightweight asynchronous scheduling in heterogeneous reconfigurable systems

The trend for heterogeneous embedded systems is the integration of accelerators and general-purpose CPU cores on the same die. In these integrated architectures, like the Zynq UltraScale+ board (CPU+FPGA) that we target in this work, hardware support for shared memory and low-overhead synchronization between the accelerator and the CPU cores make the case for exploring strategies that exploit a tight collaboration between the CPUs and the accelerator. In this paper we propose a novel lightweight scheduling strategy, FastFit, targeted to FPGA accelerators, and a new scheduler based on it, named MultiFastFit, which asynchronously tackles heterogeneous systems comprised of a variety of CPU cores and FPGA IPs. Our strategy significantly reduces the overhead to automatically compute the near-optimal chunksizes when compared to a previous state-of-the-art auto-tuned approach, which makes our approach more suitable for fine-grained applications. Additionally, our scheduler MultiFastFit has been designed to enable the efficient co-execution of work among compute devices in such a way that all the devices are busy while minimizing the load unbalance. Our approaches have been evaluated using four benchmarks carefully tuned for the low-power UltraScale+ platform. Our experiments demonstrate that the FastFit strategy always finds the near-optimal FPGA chunksize for any device configuration at a reasonable cost, even for fine-grained and irregular applications, and that heterogeneous CPU+FPGA co-executions that exploit all the compute devices are usually faster and more energy efficient than the CPU-only and FPGA-only executions. We have also compared MultiFastFit with other state-of-the-art scheduling strategies, finding that it outperforms other auto-tuned approach up to 2x and it achieves similar results to manually-tuned schedulers without requiring an offline search of the ideal CPU-FPGA partition or FPGA chunk granularity. © 2022 The Author

Asymmetric 1,3-dipolar cycloaddition reactions between enals and nitrones catalysed by half-sandwich rhodium or iridium diphosphane complexes

The aqua complexes ¿(¿5-C5Me5)M¿PP*)¿H2O)]¿SbF6]2 (M = Rh, Ir; PP* = chiral diphosphane) have been tested as catalysts for the asymmetric 1,3-dipolar cycloaddition of nitrones to a,ß-unsaturated aldehydes. Quantitative conversions with very high regioselectivity, perfect endo selectivity and excellent enantioselectivity (up to 99% ee) were achieved. The stereochemical outcome was analyzed on the basis of the stereoelectronic properties of the intermediate enal complexes of the formula ¿(¿5-C5Me5)M¿PP*)¿enal)]¿SbF6]2

Aminopirimidinas y derivados. 25. Síntesis de intermedios versátiles para la preparación de 7-glicosilpurinas

Se han preparado 5-formilamino-4-glicosilaminopirimidinas (IV), por reacción de los correspondientes 5-amino derivados (III) con ácido fórmico. Los compuestos III se prepararon por nitrosación de las 4-glicosilaminopirimidinas (I) y posterior reducción de los 5-nitroso derivados (II). Todas estas reacciones transcurren con rendimientos elevados y en condiciones de reacción muy suaves.5-Formylamino-4-glycosylaminopyrimidines (IV) have been obtained by reaction of the corresponding 5-amino derivatives (111) with formic acid. Compounds III were prepared by nitrosation of the 4-g1ycosylaminopyrimidines (1) and subsequent reduction of the 5-nitroso derivatives (H) thus obtained. AH these reactions took place in high yields and under very mi Id conditions

Aminopirimidinas y derivados. 25. Síntesis de intermedios versátiles para la preparación de

5-Formylamino-4-glycosylaminopyrimidines (IV) have been obtained by reaction of the corresponding 5-amino derivatives (III) with formic acid. Compounds III were prepared by nitrosation of the 4-glycosylaminopyrimidines (I) and subsequent reduction of the 5-nitroso derivatives (II) thus obtained. All these reactions took place in high yields and under very mi Id conditions.Se han preparado 5-formilamino-4-glicosilaminopirimidinas (IV), por reacción de los correspondientes 5-amino derivados (III) con ácido fórmico. Los compuestos III se prepararon por nitrosación de las 4-glicosilaminopirimidinas (I) y posterior reducción de los 5-nitroso derivados (II). Todas estas reacciones transcurren con rendimientos elevados y en condiciones de reacción muy suaves

A simple and efficient method to allocate costs and benefits in energy communities

Purpose: Define a simple and efficient method to allocate costs and benefits in energy communities, and characterize some of its key properties. Design/methodology/approach: The approach is theoretical. We define an algorithm to allocate costs and benefits in energy communities, and derive some of its formal properties using mathematical reasoning. We also compare the proposed algorithm with several alternatives. Findings: The proposed algorithm is simple and it ensures that the resulting distribution of costs and benefits is (i) beneficial for every member of the community, (ii) efficient, (iii) fair (in a formally defined sense), (iv) smooth (small changes in the consumption or in the generation of energy cannot lead to big changes in the allocation of costs and benefits), and (v) environmentally friendly in the sense that the individual allocated cost is a strictly increasing function of individual consumption. Research limitations/implications: The properties of the proposed algorithm are satisfied for a specific type of energy community that is defined in the manuscript.    Practical implications: The algorithm is easy to implement in any energy community. Social implications: The algorithm is highly relevant for any community of prosumers who are willing to exchange energy internally. It guarantees a number of desirable properties that are formally defined in the paper. Originality/value: We prove that a simple algorithm to allocate costs and benefits in energy communities guarantees the fulfilment of several desirable properties