Catalytic formation of C(sp(3))-F bonds via heterogeneous photocatalysis

Due to their chemical, physical, and biological properties, fluorinated compounds are widely employed throughout society. Yet, despite their critical importance, current methods of introducing fluorine into compounds suffer from severe drawbacks. For example, several methods are noncatalytic and employ stoichiometric equivalents of heavy metals. Existing catalytic methods, on the other hand, exhibit poor activity, generality, selectivity and/or have not been achieved by heterogeneous catalysis, despite the many advantages such an approach would provide. Here, we demonstrate how selective C(sp3)–F bond synthesis can be achieved via heterogeneous photocatalysis. Employing TiO2 as photocatalyst and Selectfluor as mild fluorine donor, effective decarboxylative fluorination of a variety of carboxylic acids can be achieved in very short reaction times. In addition to displaying the highest turnover frequencies of any reported fluorination catalyst to date (up to 1050 h–1), TiO2 also demonstrates excellent levels of durability, and the system is catalytic in the number of photons required; i.e., a photon efficiency greater than 1 is observed. These factors, coupled with the generality and mild nature of the reaction system, represent a breakthrough toward the sustainable synthesis of fluorinated compounds

The interactive physics flight simulator

This paper describes a modelling approach to the dynamics of the airplane flight aimed at designing and realizing a simple but realistic “flight simulator”, able to mimic the longitudinal behaviour of a real airplane. The model is implemented by using the Interactive Physics simulation environment. The simulator is used to reproduce all the phases of a complete flight of a light commercial airplane. All the actions on plane controls are analyzed and explained in terms of equilibrium states of the system. The main objective of the obtained simulations is in making the physical phenomenon understandable to students with a basic knowledge of mechanics and not involved in specialized aerodynamics studies

Pool temperature stratification analysis in CIRCE-ICE facility with RELAP5-3D© model and comparison with experimental tests

In the frame of heavy liquid metal (HLM) technology development, CIRCE pool facility at ENEA/Brasimone Research Center was updated by installing ICE (Integral Circulation Experiments) test section which simulates the thermal behavior of a primary system in a HLM cooled pool reactor. The experimental campaign led to the characterization of mixed convection and thermal stratification in a HLM pool in safety relevant conditions and to the distribution of experimental data for the validation of CFD and system codes. For this purpose, several thermocouples were installed into the pool using 4 vertical supports in different circumferential position for a total of 119 thermocouples [1][2]. The aim of this work is to investigate the capability of the system code RELAP5-3D (c) to simulate mixed convection and thermal stratification phenomena in a HLM pool in steady state conditions by comparing code results with experimental data. The pool has been simulated by a 3D component divided into 1728 volumes, 119 of which are centered in the exact position of the thermocouples. Three dimensional model of the pool is completed with a mono-dimensional nodalization of the primary main flow path. The results obtained by code simulations are compared with a steady state condition carried out in the experimental campaign. Results of axial, radial and azimuthal temperature profile into the pool are in agreement with the available experimental data Furthermore the code is able to well simulate operating conditions into the main flow path of the test section

Pre-test analysis of protected loss of primary pump transients in CIRCE-HERO facility

In the frame of LEADER project (Lead-cooled European Advanced Demonstration Reactor), a new configuration of the steam generator for ALFRED (Advanced Lead Fast Reactor European Demonstrator) was proposed. The new concept is a super-heated steam generator, double wall bayonet tube type with leakage monitoring [1]. In order to support the new steam generator concept, in the framework of Horizon 2020 SESAME project (thermal hydraulics Simulations and Experiments for the Safety Assessment of MEtal cooled reactors), the ENEA CIRCE pool facility will be refurbished to host the HERO (Heavy liquid mEtal pRessurized water cOoled tubes) test section to investigate a bundle of seven full scale bayonet tubes in ALFRED-like thermal hydraulics conditions. The aim of this work is to verify thermofluid dynamic performance of HERO during the transition from nominal to natural circulation condition. The simulations have been performed with RELAP5-3D© by using the validated geometrical model of the previous CIRCE-ICE test section [2], in which the preceding heat exchanger has been replaced by the new bayonet bundle model. Several calculations have been carried out to identify thermal hydraulics performance in different steady state conditions. The previous calculations represent the starting points of transient tests aimed at investigating the operation in natural circulation. The transient tests consist of the protected loss of primary pump, obtained by reducing feed-water mass flow to simulate the activation of DHR (Decay Heat Removal) system, and of the loss of DHR function in hot conditions, where feed-water mass flow rate is absent. According to simulations, in nominal conditions, HERO bayonet bundle offers excellent thermal hydraulic behavior and, moreover, it allows the operation in natural circulation

Post-test simulation of a PLOFA transient test in the CIRCE-HERO facility

CIRCE is a lead–bismuth eutectic alloy (LBE) pool facility aimed to simulate the primary system of a heavy liquid metal (HLM) cooled pool-type fast reactor. The experimental facility was implemented with a new test section, called HERO (Heavy liquid mEtal pRessurized water cOoled tubes), which consists of a steam generator composed of seven double-wall bayonet tubes (DWBT) with an active length of six meters. The experimental campaign aims to investigate HERO behavior, which is representative of the tubes that will compose ALFRED SG. In the framework of the Horizon 2020 SESAME project, a transient test was selected for the realization of a validation benchmark. The test consists of a protected loss of flow accident (PLOFA) simulating the shutdown of primary pumps, the reactor scram and the activation of the DHR system. A RELAP5-3D© nodalization scheme was developed in the pre-test phase at DIAEE of “Sapienza” University of Rome, providing useful information to the experimentalists. The model consisted to a mono-dimensional scheme of the primary flow path and the SG secondary side, and a multi-dimensional component simulating the large LBE pool. The analysis of experimental data, provided by ENEA, has suggested to improve the thermal–hydraulic model with a more detailed nodalization scheme of the secondary loop, looking to reproduce the asymmetries observed on the DWBTs operation. The paper summarizes the post-test activity performed in the frame of the H2020 SESAME project as a contribution of the benchmark activity, highlighting a global agreement between simulations and experiment for all the primary circuit physical quantities monitored. Then, the attention is focused on the secondary system operation, where uncertainties related to the boundary conditions affect the computational results

Phenomenological Implications of Supersymmetric Family Non-universal U(1)-prime Models

We construct a class of anomaly-free supersymmetric U(1)' models that are characterized by family non-universal U(1)' charges motivated from E_6 embeddings. The family non-universality arises from an interchange of the standard roles of the two SU(5) 5* representations within the 27 of E_6 for the third generation. We analyze U(1)' and electroweak symmetry breaking and present the particle mass spectrum. The models, which include additional Higgs multiplets and exotic quarks at the TeV scale, result in specific patterns of flavor-changing neutral currents in the b to s transitions that can accommodate the presently observed deviations inthis sector from the SM predictions.Comment: 25 pages, 3 figure

Promotion of proliferation and metastasis of hepatocellular carcinoma by LncRNA00673 based on the targeted-regulation of notch signaling pathway

we read with great interest the paper by Dr. Chen et al1, recently published in European Review for Medical and Pharmacological Sciences and titled ‘‘Promotion of proliferation and metastasis of hepatocellular carcinoma by LncRNA00673 based on the targeted-regulation of notch signaling pathway’’. Authors concluded that lncRNA00673 is highly expressed and may be a potential target for the treatment of Hepatocellular Carcinoma (HCC). Moreover, according to authors, it can promote the proliferation and metastasis of HCC by the regulation of Notch signaling pathway. We congratulate the authors for their interesting work

Leading isospin-breaking corrections to pion, kaon and charmed-meson masses with Twisted-Mass fermions

We present a lattice computation of the isospin-breaking corrections to pseudoscalar meson masses using the gauge configurations produced by the European Twisted Mass collaboration with $N_f = 2 + 1 + 1$ dynamical quarks at three values of the lattice spacing ($a \simeq 0.062, 0.082$ and $0.089$ fm) with pion masses in the range $M_\pi \simeq 210 - 450$ MeV. The strange and charm quark masses are tuned at their physical values. We adopt the RM123 method based on the combined expansion of the path integral in powers of the $d$- and $u$-quark mass difference ($\widehat{m}_d - \widehat{m}_u$) and of the electromagnetic coupling $\alpha_{em}$. Within the quenched QED approximation, which neglects the effects of the sea-quark charges, and after the extrapolations to the physical pion mass and to the continuum and infinite volume limits, we provide results for the pion, kaon and (for the first time) charmed-meson mass splittings, for the prescription-dependent parameters $\epsilon_{\pi^0}$, \epsilon_\gamma(\overline{MS}, 2~\mbox{GeV}), \epsilon_{K^0}(\overline{MS}, 2~\mbox{GeV}), related to the violations of the Dashen's theorem, and for the light quark mass difference (\widehat{m}_d - \widehat{m}_u)(\overline{MS}, 2~\mbox{GeV}).Comment: 47 pages, 20 figures, 4 tables; comments on QED and QCD splitting prescriptions added; version to appear in PR

SU(3)-breaking effects in kaon and hyperon semileptonic decays from lattice QCD

We discuss the result of a recent quenched lattice calculation of the K -> pi vector form factor at zero-momentum transfer, relevant for the determination of |V_us| from K-> pi l nu decays. Using suitable double ratios of three-point correlation functions, we show that it is possible to calculate this quantity at the percent-level precision. The leading quenched effects are corrected for by means of quenched chiral perturbation theory. The final result, f+(0) = 0.960 +- 0.005_stat +- 0.007_syst, turns out to be in good agreement with the old quark model estimate made by Leutwyler and Roos. In this paper, we discuss the phenomenological impact of the lattice result for the extraction of |V_us|, by updating the analysis of K -> pi l nu decays with the most recent experimental data. We also present a preliminary lattice study of hyperon Sigma -> n l nu decays, based on a similar strategy.Comment: 17 pages, 8 figures. Based on talks given at: DAFNE 2004: Physics at meson factories, Laboratori Nazionali di Frascati (Italy), June 7-11, 2004; VIII International Conference on "Electron-Nucleus Scattering", Marciana Marina (Italy), June 21-25, 2004; Lattice 2004, Fermi National Accelerator Laboratory, Batavia, Illinois (USA), June 21-26, 2004; ICHEP 2004, Beijing (China), August 16-22, 200