765 research outputs found
High-pressure homogenization treatment to recover bioactive compounds from tomato peels
By-products of tomato processing are rich in bioactive compounds and their recovery might bring significant economic and environmental benefits. High-pressure homogenization (HPH) (1–10 passes at 100 MPa) was used as a disruption method to recover valuable compounds from tomato peels, using solely water as process medium. Micronization of tomato peels suspensions by HPH reduced their size distribution below the visual detection limit, because of the complete disruption of individual plant cells. With respect to high-shear mixing (5 min at 20000 rpm), HPH processing (10 passes) caused an increased release of intracellular compounds, such as proteins (+70.5%), and polyphenols (+32.2%) with a corresponding increase in antioxidant activity (+23.3%) and reduction in oil-water interfacial tension (−15.0%). Remarkably, also the release of water-insoluble lycopene in the aqueous supernatant increased, enabling the recovery of up to 56.1% of the initial peel content, well above what reported in the literature when using organic solvents or supercritical CO2
Transient Overload Characteristics of PM-Assisted Synchronous Reluctance Machines, Including Sensorless Control Feasibility
Synchronous reluctance machines are a highefficiency alternative to induction motors for variable-speed applications. To mitigate the well-known downside of their lower power factor, permanent-magnet-assisted topologies, in which either rare-earth or ferrite magnets are inserted into the rotor in suitable quantities, are often adopted. The design and optimization procedures for PM-assisted topologies have been thoroughly discussed in the related literature. This paper compares synchronous reluctance machines assisted with NdFeB and ferrite magnets, focusing on torque overload capability and feasibility of saliency-based position estimation algorithms. Three prototypes were realized and tested. They all have the stator of a commercial induction motor and the same customdesigned synchronous reluctance rotor laminations. Of the three prototypes, one is a pure synchronous reluctance motor, and the other two have NdFeB and ferrite magnets, respectively; both are designed to give the same torque at rated current. Results from simulations and experiments are presented comparing the transient overload capability of the three machines, in terms of torque capability and de-magnetization limit. A dynamic thermal model of the machines was developed within this scope. Moreover, the feasibility of saliency-based sensorless methods was investigated and is presented here for the three machines, both at high- and low-current loads. The results of the paper suggest that the ferrite-assisted solution is the best candidate for replacing induction motors in variable-speed applications, for its optimal tradeoff between performance and cost
Inferred Ising model unveils potentiation of pairwise neural interactions and replay of rule-learning related neural activity
Optical Phonons in Carbon Nanotubes: Kohn Anomalies, Peierls Distortions and Dynamic Effects
We present a detailed study of the vibrational properties of Single Wall
Carbon Nanotubes (SWNTs). The phonon dispersions of SWNTs are strongly shaped
by the effects of electron-phonon coupling. We analyze the separate
contributions of curvature and confinement. Confinement plays a major role in
modifying SWNT phonons and is often more relevant than curvature. Due to their
one-dimensional character, metallic tubes are expected to undergo Peierls
distortions (PD) at T=0K. At finite temperature, PD are no longer present, but
phonons with atomic displacements similar to those of the PD are affected by
strong Kohn anomalies (KA). We investigate by Density Functional Theory (DFT)
KA and PD in metallic SWNTs with diameters up to 3 nm, in the electronic
temperature range from 4K to 3000 K. We then derive a set of simple formulas
accounting for all the DFT results. Finally, we prove that the static approach,
commonly used for the evaluation of phonon frequencies in solids, fails because
of the SWNTs reduced dimensionality. The correct description of KA in metallic
SWNTs can be obtained only by using a dynamical approach, beyond the adiabatic
Born-Oppenheimer approximation, by taking into account non-adiabatic
contributions. Dynamic effects induce significant changes in the occurrence and
shape of Kohn anomalies. We show that the SWNT Raman G peak can only be
interpreted considering the combined dynamic, curvature and confinement
effects. We assign the G+ and G- peaks of metallic SWNTs to TO
(circumferential) and LO (axial) modes, respectively, the opposite of
semiconducting SWNTs.Comment: 24 pages, 21 figures, submitted to Phys. Rev.
Single-photon detection and cryogenic reconfigurability in Lithium Niobate nanophotonic circuits
Lithium-Niobate-On-Insulator (LNOI) is emerging as a promising platform for
integrated quantum photonic technologies because of its high second-order
nonlinearity and compact waveguide footprint. Importantly, LNOI allows for
creating electro-optically reconfigurable circuits, which can be efficiently
operated at cryogenic temperature. Their integration with superconducting
nanowire single-photon detectors (SNSPDs) paves the way for realizing scalable
photonic devices for active manipulation and detection of quantum states of
light. Here we report the first demonstration of these two key components
integrated in a low loss (0.2 dB/cm) LNOI waveguide network. As an experimental
showcase of our technology, we demonstrate the combined operation of an
electrically tunable Mach-Zehnder interferometer and two waveguide-integrated
SNSPDs at its outputs. We show static reconfigurability of our system with a
bias-drift-free operation over a time of 12 hours, as well as high-speed
modulation at a frequency up to 1 GHz. Our results provide blueprints for
implementing complex quantum photonic devices on the LNOI platform
N=2 Supersymmetric SO(N)/Sp(N) Gauge Theories from Matrix Model
We use the matrix model to describe the N=2 SO(N)/Sp(N) supersymmetric gauge
theories with massive hypermultiplets in the fundamental representation. By
taking the tree level superpotential perturbation made of a polynomial of a
scalar chiral multiplet, the effective action for the eigenvalues of chiral
multiplet can be obtained. By varying this action with respect to an
eigenvalue, a loop equation is obtained. By analyzing this equation, we derive
the Seiberg-Witten curve within the context of matrix model.Comment: 14pp;v2 refs added, clarified in page 4, 6 and 11 and the sign of
resolvent corrected;v3 improved in page 5 and 6 and the flavor dependent part
in the integration around P added and to appear in PR
Pinch-points to half-moons and up in the stars: The kagome skymap
Pinch point singularities, associated with flat band magnetic excitations, are tell-tale signatures of Coulomb spin liquids. While their properties in the presence of quantum fluctuations have been widely studied, the fate of the complementary nonanalytic features—shaped as half moons and stars—arising from adjacent shallow dispersive bands has remained unexplored. Here, we address this question for the spin S=1/2 Heisenberg antiferromagnet on the kagome lattice with second and third neighbor couplings, which allows one to tune the classical ground state characterized by flat bands to one that is governed by shallow dispersive bands for intermediate coupling strengths. Employing the complementary strengths of variational Monte Carlo, pseudofermion functional renormalization group, and density-matrix renormalization group, we establish the quantum phase diagram of the model. The U(1) Dirac spin liquid ground state of the nearest-neighbor antiferromagnet remains remarkably robust till intermediate coupling strengths when it transitions into a pinwheel valence bond crystal displaying signatures of half moons in its structure factor. Our Letter thus identifies a microscopic setting that realizes one of the proximate orders of the Dirac spin liquid identified in a recent work [Song, Wang, Vishwanath, and He, Nat. Commun. 10, 4254 (2019)]. For larger couplings, we obtain a collinear magnetically ordered ground state characterized by starlike patterns
Extracellular vesicles from patients with Acute Coronary Syndrome impact on ischemia-reperfusion injury
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