Novel propylmethacrylate-monofunctionalized polyhedral oligomeric silsesquioxanes homopolymers prepared via radical bulk free polymerization

Novel propylmethacrylate-monofunctionalized polyhedral oligomeric silsesquioxanes (POSS-PMA) homopolymers were obtained, in good yield, by free bulk radical polymerizations of the low melting macromer heptaisobutylpentacyclooctasiloxan-1-(yl)propylmethacrylate [(PMA)(i-Bu)₇T₈], 1, by using different initiator/macromer molar ratios. Their characterization was accomplished by TG, DTG and DSC analyses, Gel permeation chromatography (GPC) and MALDI-TOF mass spectrometry. The results indicate that both macromolecular as well as the thermal properties of the new materials are dependent on the initiator/macromer molar ratio used in the polymerization process. By increasing the amount of initiator, polymers with lowest molecular masses, highest molecular weight distributions (MWD) and lowest thermal stability were obtained. High value of MWD was found for all the samples. The different thermal behavior observed for the sample prepared by using the highest amount of initiator is explained by the formation of polymer branched chain, induced by chain transfer to polymer processes. MALDI-TOF mass spectra resulted diagnostic of the homopolymers compositions displaying a series of peaks corresponding to oligomeric structures present in the polymeric samples. The thermal polymerization of 1 performed without employing catalyst was also investigated. Only low yields (4%) of short oligomers (from dimer to pentamer), bearing degraded POSS cages, were isolated.     

On Asymptotic Effects of Boundary Perturbations in Exponentially Shaped Josephson Junctions

A parabolic integro differential operator \(\mathcal{L}\) , suitable to describe many phenomena in various physical fields, is considered. By means of equivalence between \(\mathcal{L}\) and the third order equation describing the evolution inside an exponentially shaped Josephson junction (ESJJ), an asymptotic analysis for (ESJJ) is achieved, explicitly evaluating, boundary contributions related to the Dirichlet problem.     

A result of suzuki type in partial G-metric spaces

Recently, Suzuki [T. Suzuki, A generalized Banach contraction principle that characterizes metric completeness, Proc. Amer. Math. Soc. 136 (2008), 1861-1869] proved a fixed point theorem that is a generalization of the Banach contraction principle and characterizes the metric completeness. Paesano and Vetro [D. Paesano and P. Vetro, Suzuki's type characterizations of completeness for partial metric spaces and fixed points for partially ordered metric spaces, Topology Appl., 159 (2012), 911-920] proved an analogous fixed point result for a self-mapping on a partial metric space that characterizes the partial metric 0-completeness. In this article, we introduce the notion of partial G-metric spaces and prove a result of Suzuki type in the setting of partial G-metric spaces. We deduce also a result of common fixed point.     

Design of transverse electric ring isolators for ultra-low-loss Si3N4 waveguides based on the finite element method

In this Letter we present the design of a novel (to our best knowledge) integrated TE isolator realized using ultra-low-loss Si(3)N(4) waveguides. The device is made of two straight waveguides coupled to an array of ring resonators including a Ce:YIG garnet grown on their internal side. The analysis demonstrates advantages in loss, isolation, and passband width as the number of rings is increased.     

Long-range simplex-coded BOTDA sensor over 120 km distance employing optical preamplification

In this Letter, we combine the use of optical preamplification at the receiver and optical pulse coding techniques with an optimized modulation format to effectively extend the sensing range of Brillouin optical time-domain analysis (BOTDA) sensors. Combining a return-to-zero modulation format with 25% duty cycle and linear gain preamplification allows for temperature and strain measurements over 120 km of standard single-mode fiber with 3 m spatial resolution and an rms strain-temperature accuracy of 3.1 °C/60 με respectively.     

Activity and stereoselectivity of Ru-based catalyst bearing a fluorinated imidazolinium ligand

Grubbs II generation catalyst (3), bearing a fluorinated imidazolinium ligand, was investigated in cross metathesis (CM), ring closing metathesis (RCM) and ring opening polymerization metathesis (ROMP) for a variety of substrates. Kinetic studies showed reduced stability of the catalyst in methylene chloride following the first 15 minutes of reaction preventing a higher efficiency despite the very high activity. Beneficial solvent effects on the catalyst stability were observed by performing RCM in C₆F₆.      

Evaluation of different adsorbents for large-volume pre-concentration for analyzing atmospheric Persistent Organic Pollutants at trace levels

This paper investigates the performance of some adsorbents, Carbopack B, Tenax-GC, and XAD-2, in a SPE and GC analytical method for sampling and determining some persistent organic pollutants such as benzene, toluene, o-, m-, and p-xylenes, naphthalene, anthracene, fluorene, fluoranthene, benzo(i,k)fluorene, pyrene and benzo(a)pyrene, aldrin, dieldrin, endrin, endosulfan, and PCB congeners (nos. 1, 15, 44, 77, and 209). Adsorbents evaluated in this study are Carbopack B, Tenax-GC, and XAD-2. Before applying the analytical method to air samples, it was widely investigated in laboratory: the sampler is constituted by a glass pyrex vial home-filled with 300 mg (sampling section) and 50 mg of adsorbent material (backup section). The re-extraction is performed by CS₂ (1–2 mL) and analysis is performed by GC-FID and GC-ECD. The evaluation of breakthrough volumes and desorption efficiencies shows the XAD-2 performance in the enrichment of different organic species present in atmosphere at trace levels (ppt) to be more advantageous than the other two materials in terms of analytical and technical parameters. One of the advantages is the high volume of sampled air with high concentration factor and limited loss of analytes (breakthrough volumes are higher than 5,000 L g⁻¹ for high-boiling compounds and higher than 400 L g⁻¹ for low-boiling solutes). Another advantage is the possibility of easy and speed re-extraction of analytes using small volumes of solvent (a few milliliters). The recoveries are about 100% with a RSD ≤ 2.3 for low-boiling compounds, and between 77% and 109% with a RSD ≤ 5.7% for high-boiling species. The XAD-2 adsorbent was applied to real air samples collected in different polluted areas (urban, industrial, rural, and remote locations) demonstrating the wide application of such methodology in various environmental situation.     

Effects of lipoic acid, caffeic acid and a synthesized lipoyl-caffeic conjugate on human hepatoma cell lines

Hepatocellular carcinoma (HCC) is among the most aggressive and fatal cancers. Its treatment with conventional chemotherapeutic agents is inefficient, due to several side effects linked to impaired organ function typical of liver diseases. Consequently, there exists a decisive requirement to explore possible alternative chemopreventive and therapeutic strategies. The use of dietary antioxidants and micronutrients has been proposed for HCC successful management. The aim of this work was to test in vitro the effects of lipoic acid, caffeic acid and a new synthesized lipoyl-caffeic conjugate on human hepatoma cell lines in order to assess their effect on tumor cell growth. The results of cytotoxicity assays at different times showed that the cell viability was directly proportional to the molecule concentrations and incubation times. Moreover, to evaluate the pro- or anti-inflammatory effects of these molecules, the cytokine concentrations were evaluated in treated and untreated cellular supernatants. The obtained cytokine pattern showed that, at the increasing of three molecules concentrations, three pro-inflammatory cytokines such as IL-1β, IL-8 and TNF-α decreased whereas the anti-inflammatory cytokine such as IL-10 increased.     

High-throughput tools for the study of protein-nanostructured surface interaction

The aim of this review is to describe and to analyze the ingredients that are necessary in order to develop a robust and effective experimental approach for the high-throughput characterization of protein-nanostructured surface interaction. In the first part of this paper we review the nanostructured surface synthesis methods that are potentially able to create nanostructured inorganic surface libraries. In the second part, we address another fundamental aspect consisting in the availability of high-throughput proteins detection methods. We describe in details new emerging analytical tools compatible with nanostructured surfaces, analyzing different possible strategies, depending on the objective of the experiment and on the library format.     

Ionic strength effects on the critical micellar concentration of ionic and nonionic surfactants: the binding model

We have recently investigated the aggregation behavior of zwitterionic n-dodecyl phosphocholine in the presence of high salt. As double logarithmic Corrin-Harkins plots of the critical micellar concentration versus the salt concentration were not linear, here we re-examine those data in the context of the binding model of surfactant aggregation, as previously developed by us for ionic surfactants. We have also re-examined plenty of data available in the literature on the salt-dependent aggregation of neutral surfactants. The use of double-logarithmic plots allowed us to show that the binding model is of general applicability. Indeed, it permits unified treatment of ionic and uncharged aggregation without requiring the introduction of linear terms in the salt concentration, as needed in the empirical Corrin-Harkins treatment of nonionic surfactants. The use of this model could be of help in a broad range of surfactant-based applications in the presence of high salt.