Volterra's kernels-based finite-time parameters estimation of the Chua system

In this work, the unknown set of parameters of the Chua system is recovered under the hypothesis that the voltages of the capacitors are available. The system is shown to be algebraically observable and identifiable with respect to the chosen outputs. Focusing on the differential equations, the Volterra kernel-based approach is used to perform an estimation without the uncertainty of the unmeasurable derivatives and the unknown initial conditions

1H, 19F, and 15N NMR study of the interaction between bis(pentafluorophenyl)borinic acid and nitrogen bases

Bis(pentafluorophenyl)borinic acid ((ArF)2BOH, ArF = C6F5, 1) is a molecule that, due to its multiple reactivity, can behave in different and not always straightforward ways in the presence of nucleophiles. It has been already shown its behaviour in dicloromethane solution in the presence of water, THF and methanol. Briefly, it exists as monomer and trimer (1m and 1t, see Chart 1), and the presence of nucleophiles strongly influence the thermodynamic and the kinetic of the monomer-trimer interconversion. Moreover, according to the nature of the nucleophile, 1 shows a camaleonic nature by forming several, sometimes unexpected, species.2,3 We have studied now the reaction of 1 in the presence of nitrogen bases, that can act as Lewis and Br\uf8nsted bases. Two nitrogen bases were studied, namely 1,8-bis(dimethylamino)naphthalene (DMAN), which can act as Br\uf8nsted base only, and pyridine, which is a good Lewis base but weak Br\uf8nsted base. First of all, the Br\uf8nsted base DMAN has been proved to be more efficient than oxygenated Lewis bases in catalyzing the trimerization process. Indeed it is enough a catalytic amount of base to cause the complete trimerization of 1. The so obtained trimeric deprotonated anion 2 (Chart 2) is unstable with respect to dearylation reactions, leading eventually (in the presence of more than 0.33 equiv of DMAN and at higher temperatures) to the tetrarylic species 3 (Chart 2). On the other hand, the behaviour of pyridine is quite different, since 0.33 equiv of base are requested to complete the trimerization of 1, and also in this case the obtained trimer is anionic. Moreover, the presence of 1 equivalent of pyridine does not cause the dearylation process but gives rise to the monomeric neutral 1:1 adduct 4 (Chart 2). Both the identification and the characterization of the involved species were performed by multiparametric and multinuclear low temperature NMR spectroscopy

A proxy cost model for tramway services

In this paper, we build a proxy cost model for tramway services. we estimate separately: (i) transport services production costs; (ii) infrastructure costs; (iii) maintenance costs; (iv) administrative and general costs and (v) the cost of capital. we apply the proposed methodology to estimate the standard cost of italian tramway services. detailed data about costs, technical and environmental characteristics were collected by means of questionnaires sent to italian companies providing 100% of tramway services in 2012. we perform a simulation study in order to highlight the marginal impact of efficiency gains obtained by manipulating cost-driving variables both under the control of the operators (trains and drivers productivity) and of the local authority who assigns the service (number of train revenue kilometers (trK) assigned within the service contract, average fleet age). the simulations show how the local authority should allocate extra resources if it wants to increase the quality-quantity mix of tramway services. our results might help the decision-maker to define the maximum economic compensation (auction base) in competitive tendering procedures or a benchmark for the bargaining with the local monopolist

1H NMR Characterization of Organic and Inorganic Nanoparticles

Drug delivery employing nano-object as liposomes, polymer conjugates, and nanoparticles suspended in solution is a subject of high current interest [1]. The characterization of the size and the surface functionalization of these nanoparticles is of primary importance. Microscopy techniques give information on deposited colloidal samples, after solvent evaporation, so that the correspondence with the nature of the species in solution is not granted. Dynamic Light Scattering (DLS), which is usually used to estimate the size of a colloidal sample in solution, can overestimate the radii of very small nanoparticles [2]. Diffusion NMR, and in particular Pulsed gradient spin-echo (PGSE) technique, has recently emerged as a valuable tool for colloids characterization [3], complementary to DLS from the point of view of the size evaluation, being highly reliable for the measurement of the smallest particles. Moreover, NMR provide information not only on the size, but also on the interaction between the capping ligands and the nanoparticle surface. In this work, we present the characterization through 1H PGSE NMR measurements of the size of spherical and rod-like TiO2/oleic acid nanoparticles and of conjugates between Re complexes and polyamidoamine nanoparticles. Moreover, by 1H NMR experiments the interaction between TiO2 and the capping oleic acid (OA) has been characterized. [1] a) A. H. Faraji, P. Wipf, Bioorganic and Medicinal Chemistry 2009, 17, 2950-2962; b) S. M. Garg, A. V. Deshmukh, Nano Science and Nano Technology 2007, 1(2), 45-58; c) C. Khemtong, C. W. Kessinger, J. Gao, Chem. Commun. 2009, 3497-3510. [2] C. Sanna, C. La Mesa, L. Mannina, P. Stano, S. Viel, A. Segre, Langmuir 2006, 22, 6031-6041. [3] a) F. Ribot, V. Escax, C. Roiland, C. Sanchez, J. C. Martins, M. Biesemans, I. Verbruggen, R. Willem, Chem. Commun. 2005, 1019-1021; b) M. Valentini, A. Vaccaro, A. Rehor, A. Napoli, J. A. Hubbell, N. Tirelli, J. Am. Chem. Soc. 2004, 126, 2142-2147

Path Planning and Obstacles Avoidance using Switching Potential Functions

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Liver infection and COVID-19: the electron microscopy proof and revision of the literature

OBJECTIVE: COVID-19, the newly emerging infectious disease, has been associated with acute liver injury, often related to progression to severe pneumonia. The association between moderate-severe liver injury and more severe clinical course of COVID-19 has suggested that liver injury is prevalent in severe than in mild cases of COVID-19, while no difference in liver involvement has been reported between survivors and non-survivors. The spectrum of liver involvement during COVID-19 ranges from an asymptomatic elevation of liver enzymes to severe hepatitis. Only rarely, cases with acute hepatitis have been reported in the absence of respiratory symptoms. Both epithelial and biliary cells possess the angiotensin-converting enzyme-2 receptors that SARS-CoV-2 uses to be internalized. However, to our knowledge, no ultrastructural identification of the virus in liver cells has been reported to date. Here we provide evidence of SARS-CoV-2 in the liver of two patients, a 34-year-old woman and a 60-year-old man with COVID-19.PATIENTS AND METHODS: We investigated two patients with COVID-19 showing several virions within cytoplasmic vacuoles of cholangiocytes and in endothelial cells of hepatic sinusoids. In both patients, we performed histological and ultrastructural examinations by liver biopsy. After two months, both patients were free of symptoms, and the SARS-CoV-2 infection had resolved.RESULTS: Liver biopsy histological and ultrastructural examination showed liver injury and several virions within cytoplasmic vacuoles of cholangiocytes and in endothelial cells of hepatic sinusoids.CONCLUSIONS: Although most studies in COVID-19 have been focused on the lungs, recently, cholestatic liver pathology has been introduced in the spectrum of pathological changes related to COVID-19. To the best of our knowledge, those presented in this paper are the first images of hepatic SARS-CoV-2 infected liver cells. Our findings suggest a role for cholangiocytes and biliary structures in the COVID-19

Solution conformation and dynamics of the ion pairs originating from the reaction of B(C6F5)(3) with bisindenyl dimethyl zirconium complexes

The two ion pairs [(4,7-Me(2)indenyl)(2)ZrMe](+)[MeB(C6F5)(3)](-) (1b) and [(indenyl)(2)ZrMe](+) [MeB(C6F5)(3)](-) (2b) have been generated in situ by reaction of stoichiometric B(C6F5)(3) with the corresponding dimethyl zirconocenes. It has been shown that molecular mechanics computations, guided by experimental H-1/H-1 NOE correlations, can provide information on the conformers present in solution. The dynamics of the ion pairs has also been investigated, showing the occurrence of both the processes previously characterized for this class of compounds, namely the B(C6F5)(3) migration between the two methyl groups and dissociation-recombination of the whole [MeB(C6F5)(3)](-) anion, the latter process being much faster than the first one (about three order of magnitude). Moreover, it has been shown that in certain conditions intermolecular processes can occur, which mimic the above-mentioned dissociative exchanges. In particular, the presence of species containing loosely bound [MeB(C6F5)(3)](-) anion fastens the exchange of this anion, while the presence of free B(C6F5)(3) accelerates its exchange between the two methyl sites

Viral genotype and HLA class II alleles influence on extra-hepatic manifestations of chronic HCV infection

Objective: To test whether an association between HCV genotype, HLA class II alleles distribution and extra-hepatic manifestations (EHM ) can be demonstrated in a group of Italian patients with chronic HCV infection . Methods: Sixty patients affected by HCV infection with EHM were consecutively enrolled. 163 HCV patients without EHM were tested as controls for the prevalence of HCV genotypes, while we referred to literature as to the controls for HLA distribution. HCV-RNA was quantified by a RT-PCR. HLA class II alleles typing was performed using a standard microlymphocytotoxicity assay. We used chi-square or Fisher test (p<0.05 significant). Odds Ratio (OR) was performed by 2X2 contingency table. Results: HCV 2c genotype was found in 63.46% of patients compared to 19.63% of controls (p<0.0001; OR=7.11). Furthermore, it correlated with carpal tunnel syndrome (p=0.03; OR=4.5) and autoimmune thyroiditis (p=0.02; OR=9.2). On the contrary, 1b genotype protected from EHM in toto (p=0.0004; OR=0.21) and particularly from carpal tunnel syndrome (p=0.0014; OR=0.07). Moreover, 3a genotype prevented HCV people from having cryoglobulinemia (p=0.05; OR=0.11). As to HLA, DR6 seemed to facilitate EHM in HCV patients (p=0.041; OR=1.61), while DQ2 (p=0.03; OR=0.5) and DQ3 (p=0.002; OR= 0.5) may play a protective role. In addition, HLA DR3 was associated with cryoglobulinemia (p=0.02; OR=9.5). Conclusions: According to our findings, 2c genotype can be considered as a major risk factor for developing HCVrelated EHM, while 1b genotype seems to prevent their onset; there are also evidences suggesting that HLA might play a role in chronic HCV infected patients

Aggregation and ionization equilibria of bis(pentafluorophenyl)borinic acid driven by hydrogen-bonding with tetrahydrofuran

Bis(pentafluophenyl)borinic acid, Ar2BOH (1, Ar = C6F5), in dichloromethane solution is present as an equilibrium mixture of monomeric (1m) and trimeric (1t) forms. Previous studies showed that water affects both the position and the rate of this equilibrium. Here, the behavior of 1 in the presence of tetrahydrofuran (THF), a nucleophile able to behave as a Lewis base and H-bond acceptor only, has been studied, by monitoring with H-1 and F-19 NMR the course of titrations performed directly into NMR tubes. The addition, at 183 K, of 0.33 equiv of THF caused the instantaneous and quantitative formation of the hydrogen-bonded adduct between the trimer 1t and one molecule of THF. Homo- and heteronuclear 2D NMR correlation experiments led to a solution structure consistent with the C2-optimized geometry obtained by PM3 computations. The H-bonding of the THF molecule causes major deformations of the molecular geometry of the trimer, so that only one molecule of THF can interact with the trimer, in spite of its three OH groups. Intra- and intermolecular exchange processes involving this adduct have been investigated by 2D EXSY experiments, showing flopping of the cycle conformation, rotation of the aromatic rings around their B-C bonds, and exchange of THF among the three OH groups, in addition to the exchange between free 1t and the adduct. When the amount of added THF was higher than 0.33 equiv, an unexpected ionization process occurred, leading to the cation [Ar2B(OH2)2]+ and to deprotonated 1t, i.e., to the anion [Ar6B3O3H2]- of Cs symmetry. On increasing the temperature, progressive partial fragmentation of the trimeric species was observed. Both B-11 NMR evidence and PM3 computations indicated that, at variance with what is observed in the interaction with H2O, the interaction between THF and 1m occurs preferentially via an H-bonded adduct, Ar2BO-H...THF, rather than a Lewis acid-base complex, Ar2B(OH)(THF). This confirms the poor Lewis acidity of the boron atom of 1m

Competition studies on the activation of the C-H bond of diazines by the unsaturated triangular cluster anion [Re3(\u3bc-H) 4(CO)10]

The reactions of the unsaturated cluster anion [Re3(\u3bc-H) 4(CO)10]- (1) with 1,2-, 1,3- and 1,4-diazines (used as solvents) have been investigated. The reaction with 1,2-diazine at room temperature gives quantitatively the anion [Re3(\u3bc-H) 2(\u3bc-\u3b72-N2C4H 4)(CO)10]- (3), containing a diazine bridging through the two N atoms, characterised by single crystal X-ray analysis. The orthometallated isomer [Re3(\u3bc-H)3(\u3bc-\u3b7 2-N2C4H3)(CO)10] - (4) was obtained by refluxing 3 in toluene. The reaction of [NEt4]1 in molten 1,4-diazine (60\ub0C) affords the anion [Re 3(\u3bc-H)3(\u3bc-\u3b72-N2C 4H3)(CO)10]- (5), containing orthometallated pyrazine. The slow reaction of [NEt4]1 with 1,3-diazine at room temperature gives two orthometallated isomers 6, corresponding to the metallation of carbon C2 (6a) and C6 (6b), respectively (6b/6a ratio ca. 1.2). Differently from what previously found for the analogous cluster anion containing orthometallated pyridine, the metallation reaction of diazines showed little reversibility, and poor conversion of 5 and 6 to the starting anion 1 was observed after several days under 100 atm of H 2. Competition experiments, performed by dissolving [NEt 4]1 in equimolar mixtures of pyridine/pyrazine or pyridine/pyrimidine, showed that the anion with metallated pyridine was the kinetically preferred product and that at longer times it slowly converted to the derivatives with metallated diazines (5 or 6). \ua9 2003 Elsevier Science B.V. All rights reserved