Quantum Randomness Certified by the Uncertainty Principle

We present an efficient method to extract the amount of true randomness that can be obtained by a Quantum Random Number Generator (QRNG). By repeating the measurements of a quantum system and by swapping between two mutually unbiased bases, a lower bound of the achievable true randomness can be evaluated. The bound is obtained thanks to the uncertainty principle of complementary measurements applied to min- and max- entropies. We tested our method with two different QRNGs, using a train of qubits or ququart, demonstrating the scalability toward practical applications.Comment: 10 page

MICRORNA-125A-3P NEGATIVELY REGULATES OLIGODENDROGLIAL MATURATION AND RE-MYELINATION: MOLECULAR MECHANISMS AND CLINICAL IMPLICATIONS

Multiple sclerosis (MS) is a chronic immune-mediated de-myelinating disease of the central nervous system in which immune system attacks myelin, a substance produced by mature oligodendrocytes that normally surrounds and protects axons, leading to abnormal impulses transmission (Wu et al., 2011). During their maturation oligodendroglial precursors cells (OPCs) follow a very precise differentiation program, finely orchestrated by transcription factors, epigenetic factors and microRNAs, a class of small non-coding RNAs involved in post-transcriptional regulation (He and Lu, 2013). Any alterations in this program can potentially contribute to dysregulated myelination, impaired re-myelination and neurodegenerative conditions, as it happens in multiple sclerosis. Based on these considerations, the aim of this study was to investigate the potential role of miR-125a-3p, a brain enriched miRNA, in the regulation of OPC maturation and to assess whether its alteration can contribute to MS pathogenesis or re-myelination failure. First, our gene ontology based study showed that several of its predicted target mRNAs are involved in glial cell differentiation, myelination, axon ensheathment and oligodendrocyte differentiation, suggesting that miR-125a-3p may have a primary role in the regulation of these processes. Then, we characterized its expression pattern in the CNS, showing that it is expressed in oligodendroglial cells throughout brain development and is progressively up-regulated during OPC in vitro differentiation. We also found that the over-expression of this miRNA impairs, whereas its silencing promotes oligodendrocyte maturation in vitro, likely acting on different targets at multiple levels of the process. Interestingly, we observed an up-regulation of miR-125a-3p in two different mouse models of toxic demyelination, induced by cuprizone or lysolecithin administration, suggesting that it may represent a hallmark of de-myelination. Furthermore, the over-expression of miR-125a-3p in the white matter of mice following lysolecithin-induced demyelination maintained oligodendrocytes in the NG2-positive precursor stage, in line with the hypothesis of a delay in both their maturation and the subsequent re-myelination process. To identify new mechanisms altered by miR-125a-3p during OPC maturation, we performed a transcriptomic analysis after its over-expression in OPCs, showing that miR-125a-3p can modulate different pathways and processes, such as Wnt-signaling and expression of ECM and adhesion molecules. Globally, our data suggest that miR-125a-3p could represent a new negative regulator of re-myelination and that an antago-miRNA specific for this miRNA may help to foster oligodendrocyte maturation in diseases characterized by impaired myelin repair. The potential importance of miR-125a-3p in MS was also confirmed by the finding that it is up-regulated in the CSF of MS patients in the active phase of the disease, suggesting that it could represent a potential biomarker for the diagnosis or prognosis of different MS phases

Characteristics of a gold-doped electrode for application in high-performance lithium-sulfur battery

Bulk sulfur incorporating 3 wt% gold nano-powder is investigated as possible candidate to maximize the fraction of active material in the Li-S battery cathode. The material is prepared via simple mixing of gold with molten sulfur at 120 °C, quenching at room temperature, and grinding. Our comprehensive study reports relevant electrochemical data, advanced X-ray computed tomography (CT) imaging of the positive and negative electrodes, and a thorough structural and morphological characterization of the S:Au 97:3 w/w composite. This cathode exhibits high rate capability within the range from C/10 to 1C, a maximum capacity above 1300 mAh gS−1, and capacity retention between 85% and 91% after 100 cycles at 1C and C/3 rates. The novel formulation enables a sulfur fraction in the composite cathode film as high as 78 wt%, an active material loading of 5.7 mg cm−2, and an electrolyte/sulfur (E/S) ratio of 5 μL mg−1, which lead to a maximum areal capacity of 5.4 mAh cm−2. X-ray CT at the micro- and nanoscale reveals the microstructural features of the positive electrode that favor fast conversion kinetics in the battery. Quantitative analysis of sulfur distribution in the porous cathode displays that electrodeposition during the initial cycle may trigger an activation process in the cell leading to improved performance. Furthermore, the tomography study reveals the characteristics of the lithium anode and the cell separator upon a galvanostatic test prolonged over 300 cycles at a 2C rate

Degradation of Layered Oxide Cathode in a Sodium Battery: A Detailed Investigation by X-Ray Tomography at the Nanoscale

The degradation mechanism in a sodium cell of a layered Na0.48Al0.03Co0.18Ni0.18Mn0.47O2 (NCAM) cathode with P3/P2 structure is investigated by revealing the changes in microstructure and composition upon cycling. The work aims to rationalize the gradual performance decay and the alteration of the electrochemical response in terms of polarization, voltage signature, and capacity loss. Spatial reconstructions of the electrode by X-ray computed tomography at the nanoscale supported by quantitative and qualitative analyses show fractures and deformations in the cycled layered metal-oxide particles, as well as inorganic side compounds deposited on the material. These irreversible morphological modifications reflect structural heterogeneities across the cathode particles due to formation of various domains with different Na+ intercalation degrees. Besides, X-ray photoelectron spectroscopy data suggest that the latter inorganic species in the cycled electrode are mainly composed of NaF, Na2O, and NaCO3 formed by parasitic electrolyte decomposition. The precipitation of these insulating compounds at the electrode/electrolyte interphase and the related structural stresses induced in the material lead to a decrease in cathode particle size and partial loss of electrochemical activity. The retention of the NCAM phase after cycling suggests that electrolyte upgrade may improve the performance of the cathode to achieve practical application for sustainable energy storage

The role of synthesis pathway on the microstructural characteristics of sulfur-carbon composites: X-ray imaging and electrochemistry in lithium battery

Two synthesis pathways are adopted to tune the microstructural characteristics of sulfur-carbon (S-C) composites for application in lithium-sulfur (Li-S) batteries. Both methods include intimate mixing of either carbon black or multiwalled carbon nanotubes with elemental sulfur, molten according to the first approach while dispersed in alcohol and heated according to the second one. Nano- and micro-scale X-ray computed tomography supported by X-ray diffraction and electron microscopy shows materials consisting of crystalline sulfur clusters (70 wt%) with size ranging from about 5 to 50 μm, surrounded by carbon. The sulfur cluster size appears limited by direct mixing of molten sulfur and carbons, in particular when carbon black is employed, whilst it is increased by exploiting the alcohol dispersion. Electrochemistry reveals that small sulfur particles lead to an improved rate capability in Li-S cells, whereas large active material domains may favor the capacity retention. The composites using carbon black nanoparticles exhibit the highest reversible capacity, with a maximum value exceeding 1500 mAh gS−1, whereas the composites involving multiwalled carbon nanotubes show the best capacity retention, with values approaching 70% over 150 cycles. Our multi-disciplinary approach will shed light on significant aspects aiming to enhance the Li-S battery and favor a practical application

Biology of Telenomus pachycoris (Hymenoptera: Scelionidae), a parasitoid of eggs of Pachycoris torridus (Hemiptera: Scutelleridae): the effects of egg age, exposure time, and temperature.

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Simple source device-independent continuous-variable quantum random number generator

Phase-randomized optical homodyne detection is a well-known technique for performing quantum state tomography. So far, it has been mainly considered a sophisticated tool for laboratory experiments but unsuitable for practical applications. In this work, we change the perspective and employ this technique to set up a practical continuous-variable quantum random number generator. We exploit a phase-randomized local oscillator realized with a gain-switched laser to bound the min-entropy and extract true randomness from a completely uncharacterized input, potentially controlled by a malicious adversary. Our proof-of-principle implementation achieves an equivalent rate of 270 Mbit/s. In contrast to other source-device-independent quantum random number generators, the one presented herein does not require additional active optical components, thus representing a viable solution for future compact, modulator-free, certified generators of randomness