Initial polymerization reactions in particle-forming Ar/He/C2H2 plasmas studied via quantitative mass spectrometry

The initial polymerization reactions in particle forming Ar/He/C 2H 2 plasmas are studied using molecular beam mass spectrometry (MBMS). The measured mass spectra are disentangled and quantified with the help of Bayesian probability theory. This approach uses the measured mass spectra and the cracking patterns (CPs) of the species that are formed in the plasma as the main input parameter. The CPs are either taken from calibration measurements or the NIST database or estimated based on a comparison to CPs of similar molecules. These estimated CPs are then modified by Bayesian analysis to fit the measured data. The CPs of C 6H 2, C 6H 4, and C 8H 2, which are not available in the NIST database, are determined in this way and can serve as good estimation until precise data is published. The temporal evolution after plasma ignition of the densities of in total 22 species (hydrocarbons, noble gases, and impurities) are quantified and expressed as partial pressures. The most abundant products in our plasma are C 4H 2 and C 6H 2 molecules with maximum partial pressures of 0.1 and 0.013 Pa, respectively. Our quantitative data can be used to validate plasma chemistry models. First comparison is made to a plasma chemistry model of similar C 2H 2 plasma already available in the literature. The comparison indicates that dissociative electron attachment to C 2 n H 2 ( n > 1) molecules is a dominant source of negative ions in C 2H 2 plasmas. Additionally, the C 2H 4 has been identified as a precursor for C n H 4 molecules.     

Synthesis of water-soluble nucleotide-calixarene conjugates and preliminary investigation of their in vitro DNA replication inhibitory activity

Calix[4]arenes bearing four thymine or adenine 2′-deoxynucleotide moieties have been synthesized and characterized by NMR and ESI-MS analysis. Due to their amphiphilic nature, the conjugates (2a and 2b) obtained tend to self-assemble in aqueous medium by stacking interactions. Their good water solubility makes 2a and 2b promising candidates for bioorganic applications. A preliminary study has provided evidence of their inhibitory activity toward the replication of a Penicillium digitatum DNA fragment via PCR (polymerase chain reaction).     

Emergent gravity and ether-drift experiments

According to several authors, gravity might be a long-wavelength phenomenon emerging in some ‘hydrodynamic limit’ from the same physical, flat-space vacuum viewed as a form of superfluid medium. In this framework, light might propagate in an effective acoustic geometry and exhibit a tiny anisotropy that could be measurable in the present ether-drift experiments. By accepting this view of the vacuum, one should also consider the possibility of sizeable random fluctuations of the signal that reflect the stochastic nature of the underlying ‘quantum ether’ and could be erroneously interpreted as instrumental noise. To test the present interpretation, we have extracted the mean amplitude of the signal from various experiments with different systematics, operating both at room temperature and in the cryogenic regime. They all give the same consistent value \({\langle A \rangle ={\mathcal O}(10^{-15})}\) which is precisely the magnitude expected in an emergent-gravity approach, for an apparatus placed on the Earth’s surface. Since physical implications could be substantial, it would be important to obtain more direct checks from the instantaneous raw data and, possibly, with new experimental set-ups operating in gravity-free environments.     

Novel Tyrosine Kinase Inhibitors to Target Chronic Myeloid Leukemia

This paper reports on a novel series of tyrosine kinase inhibitors (TKIs) potentially useful for the treatment of chronic myeloid leukemia (CML). The newly designed and synthesized compounds are structurally related to nilotinib (NIL), a second-generation oral TKI, and to a series of imatinib (IM)-based TKIs, previously reported by our research group, these latter characterized by a hybrid structure between TKIs and heme oxygenase-1 (HO-1) inhibitors. The enzyme HO-1 was selected as an additional target since it is overexpressed in many cases of drug resistance, including CML. The new derivatives 1a–j correctly tackle the chimeric protein BCR-ABL. Therefore, the inhibition of TK was comparable to or higher than NIL and IM for many novel compounds, while most of the new analogs showed only moderate potency against HO-1. Molecular docking studies revealed insights into the binding mode with BCR-ABL and HO-1, providing a structural explanation for the differential activity. Cytotoxicity on K562 CML cells, both NIL-sensitive and -resistant, was evaluated. Notably, some new compounds strongly reduced the viability of K562 sensitive cells.     

Azobenzene-bridged calix[8]arenes

An azobenzene bridge was introduced into the lower (or smaller) rim of p-tert-butylcalix[8]arene (1) and 1,5-calix[8]crown-3 (2) to form 1,4-singly bridged (3) and 1,5:3,7-doubly bridged (4) calix[8]arene derivatives, respectively. Trans and cis isomers of conformationally rigid 4 were isolated. The quantum yields of the trans-cis photoisomerisation reactions have been measured.     

Precision tests with a new class of dedicated ether-drift experiments

In principle, by accepting the idea of a non-zero vacuum energy, the physical vacuum of present particle physics might represent a preferred reference frame. By treating this quantum vacuum as a relativistic medium, the non-zero energy-momentum flow expected in a moving frame should effectively behave as a small thermal gradient and could, in principle, induce a measurable anisotropy of the speed of light in a loosely bound system as a gas. We explore the phenomenological implications of this scenario by considering a new class of dedicated ether-drift experiments in which arbitrary gaseous media fill the resonating optical cavities. Our predictions cover most experimental set ups and should motivate precise experimental tests of these fundamental issues. PACS  11.30.Cp; 11.30.Qc; 03.30.+p     

Design, synthesis, and drug solubilising properties of the first folate-calix[4]arene conjugate

The first example of a folate-calix[4]arene conjugate was designed and synthesized via microwave-assisted click chemistry. In PBS medium at physiological pH, the conjugate formed soluble aggregates and showed the capability to improve the water-solubility of a hydrophobic drug model, such as indomethacin.     

Investigation about the modes in the cylindrical cavity of an ECR ion source

Both theoretical and numerical electromagnetic analyses about the modes inside the cylindrical cavity of superconducting electron cyclotron resonance ion source (SERSE) have been performed. Modes close to 14, 18 and 28 GHz frequencies, usually employed in SERSE operating conditions, have been calculated in vacuum and when the chamber is filled with a uniform non-collisional plasma at different electron densities. To consider the holes present in the chamber flanges, a numerical approach has been used, by means of the HFSS^TM electromagnetic simulator, for the first mode in the cavity. Modes in a plasma-filled cylindrical cavity with holed bases have full width half maximum bandwidths larger with regard to the closed cavity in vacuum, and it leads to an increased mode frequency overlap. A monochromatic electromagnetic wave feeding this cavity can, in principle, excite different modes. Further investigations about the coupling between the SERSE cavity and its feeding waveguides have to be performed.     

Variable neighbourhood search for the minimum labelling Steiner tree problem

We present a study on heuristic solution approaches to the minimum labelling Steiner tree problem, an NP-hard graph problem related to the minimum labelling spanning tree problem. Given an undirected labelled connected graph, the aim is to find a spanning tree covering a given subset of nodes of the graph, whose edges have the smallest number of distinct labels. Such a model may be used to represent many real world problems in telecommunications and multimodal transportation networks. Several metaheuristics are proposed and evaluated. The approaches are compared to the widely adopted Pilot Method and it is shown that the Variable Neighbourhood Search that we propose is the most effective metaheuristic for the problem, obtaining high quality solutions in short computational running times.     

Spontaneous symmetry breaking in an O(2) invariant scalar theory

A simple variational principle for an O(2) invariant scalar theory, within the framework of gaussian wave functionals, is presented. The conditions for the occurrence of spontaneous symmetry breaking are discussed. The limits of validity of the gaussian approximation are also analyzed in detail.