Toward the preparation of a nanocomposite material through surface initiated controlled/“living” radical polymerization of styrene inside the channels of MCM-41 silica

A hybrid organic–inorganic material was prepared by surface initiated controlled/“living” radical polymerization (CRP) of styrene in the internal space of a MCM-41 silica. The inorganic precursor was synthesized, via sol–gel, using tetraethoxysilane and cetyltrimethylammonium bromide, in the presence of ammonia and ethanol to induce the formation of submicrometric spherical particles. After characterization by powder X-ray diffraction (XRD), transmission electron micrography (TEM), scanning electron micrography (SEM), N₂ adsorption and titration of the surface silanol groups, the mesoporous silica was functionalized through a 3-step grafting process, in order to link the nitroxide initiator to the inorganic matrix (TEMPO-MCM-41). The anchorage of the TEMPO-based initiator was checked by diffuse reflectance infrared spectroscopy (DRIFT-IR). Experimental data confirmed that the styrene polymerization occurred inside the MCM-41 channels system.     

Probing the pH Microenvironment of Mesenchymal Stromal Cell Cultures on Additive‐Manufactured Scaffolds

Despite numerous advances in the field of tissue engineering and regenerative medicine, monitoring the formation of tissue regeneration and its metabolic variations during culture is still a challenge and mostly limited to bulk volumetric assays. Here, a simple method of adding capsules‐based optical sensors in cell‐seeded 3D scaffolds is presented and the potential of these sensors to monitor the pH changes in space and time during cell growth is demonstrated. It is shown that the pH decreased over time in the 3D scaffolds, with a more prominent decrease at the edges of the scaffolds. Moreover, the pH change is higher in 3D scaffolds compared to monolayered 2D cell cultures. The results suggest that this system, composed by capsules‐based optical sensors and 3D scaffolds with predefined geometry and pore architecture network, can be a suitable platform for monitoring pH variations during 3D cell growth and tissue formation. This is particularly relevant for the investigation of 3D cellular microenvironment alterations occurring both during physiological processes, such as tissue regeneration, and pathological processes, such as cancer evolution.     

Amphiphilic NO-donor antioxidants

Models of amphiphilic NO-donor antioxidants 24-26 were designed and synthesized. The products were obtained by linking a lipophilic tail (C(6), C(8), C(10)) with a polar head constituted by the 2,6-dimethoxyphenol antioxidant joined to the NO-donor 3-furoxancarboxamide substructure through a bridge containing a quaternary ammonium group. Compound 23, containing the shortest C(2)-alkyl chain, was also studied as a reference. The antioxidant properties (TBARS and LDL oxidation assays) and the vasodilator properties of the compounds were studied in vitro. The ability of these products to interact with phospholipid vesicles was also investigated by NMR techniques. The results indicate that both activities are modulated by the ability of the compounds to accumulate on phospholipid layers.     

Polyethylene devices: passive samplers for measuring dissolved hydrophobic organic compounds in aquatic environments

We demonstrate the use of polyethylene devices (PEDs) for assessing hydrophobic organic compounds (HOCs) in aquatic environments. Like semipermeable membrane devices (SPMDs) and solid-phase microextraction (SPME), PEDs passively accumulate HOCs in proportion to their freely dissolved concentrations. Polyethylene-water partition constants (K(PEW)S) were measured in the laboratory for eight polycyclic aromatic hydrocarbons (PAHs), five polychlorinated biphenyls (PCBs), and one polychlorinated dibenzop-dioxin (PCDD), and these were found to correlate with octanol-water partition constants (K(OW)s; log K(PEW) = 1.13 log K(OW) - 0.86, R2 = 0.89). Temperature and salinity dependencies of K(PEW) values for the HOCs tested were well predicted with excess enthalpies of solution in water and Setschenow constants, respectively. We also showed that standards, impregnated in the PED before deployment, can be used to correct for incomplete equilibrations. Using PEDs, we measured phenanthrene and pyrene at ng/L concentrations and 2,2',5,5'-tetrachlorobiphenyl at pg/L concentrations in Boston Harbor seawater, consistent with our findings using traditional procedures. PEDs are cheap and robust samplers, competent to accomplish in situ, time-averaged passive sampling with fast equilibration times (approximately days) and simplified laboratory analyses.     

Extension of Postharvest Life of Bell Peppers with Low Oxygen

Green bell peppers ( Capsicum annum L cv California Wonder) were stored in oxygen/nitrogen mixtures at 10, 30, 50, 70 and 210 (air) ml O₂ litre⁻¹ for 4 weeks at 10°C. Decay, weight loss, colour, titratable acidity and soluble solids contents, internal CO₂ and ethylene were evaluated. After 2 weeks, 33% of the air-stored peppers had decayed while only 9% of those stored in 10 ml litre⁻¹ O₂ had decayed. The benefit of 10 ml litre⁻¹ O₂ in reducing decay continued through 4 weeks of storage. The 30 and 50 ml litre⁻¹ O₂ atmospheres slightly reduced decay for a short time while the incidence of decay in 70 ml litre⁻¹ O₂ was not different from the control. Peppers stored in 10 ml litre⁻¹ O₂ had significantly lower internal CO₂ than the air control and other low O₂ treatments. A slower decrease in green colour of peppers stored in low O₂ indicates a retardation of colour change by low O₂ treatments during storage. Low respiration and ethylene synthesis rates may be the primary factors in quality retention.     

Dysregulated Retinoic Acid Signaling in the Pathogenesis of Pseudoexfoliation Syndrome

Pseudoexfoliation (PEX) syndrome, a stress-induced fibrotic matrix process, is the most common recognizable cause of open-angle glaucoma worldwide. The recent identification of PEX-associated gene variants uncovered the vitamin A metabolic pathway as a factor influencing the risk of disease. In this study, we analyzed the role of the retinoic acid (RA) signaling pathway in the PEX-associated matrix metabolism and evaluated its targeting as a potential candidate for an anti-fibrotic intervention. We provided evidence that decreased expression levels of RA pathway components and diminished RA signaling activity occur in an antagonistic crosstalk with TGF-β1/Smad signaling in ocular tissues and cells from PEX patients when compared with age-matched controls. Genetic and pharmacologic modes of RA pathway inhibition induced the expression and production of PEX-associated matrix components by disease-relevant cell culture models in vitro. Conversely, RA signaling pathway activation by natural and synthetic retinoids was able to suppress PEX-associated matrix production and formation of microfibrillar networks via antagonization of Smad-dependent TGF-β1 signaling. The findings indicate that deficient RA signaling in conjunction with hyperactivated TGF-β1/Smad signaling is a driver of PEX-associated fibrosis, and that restoration of RA signaling may be a promising strategy for anti-fibrotic intervention in patients with PEX syndrome and glaucoma.     

A Molecular Hybrid for Mitochondria‐Targeted NO Photodelivery

The design, synthesis, spectroscopic and photochemical properties, and biological evaluation of a novel molecular hybrid that is able to deliver nitric oxide (NO) into mitochondria are reported. This molecular conjugate unites a tailored o‐CF₃‐p‐nitroaniline chromophore, for photo‐regulated NO release, and a rhodamine moiety, for mitochondria targeting, in the same molecular skeleton via an alkyl spacer. A combination of steady‐state and time‐resolved spectroscopic and photochemical experiments demonstrate that the two chromogenic units preserve their individual photophysical and photochemical properties in the conjugate quite well. Irradiation with violet light triggers NO release from the nitroaniline moiety and photoionization in the rhodamine center, which also retains considerable fluorescence efficiency. The molecular hybrid preferentially accumulates in the mitochondria of A549 lung adenocarcinoma cells where it induces toxicity at a concentration of 1 μm , exclusively upon irradiation. Comparative experiments, carried out with ad‐hoc‐synthesized model compounds, suggest that the phototoxicity observed at such a low concentration is probably not due to NO itself, but rather to the formation of the highly reactive peroxynitrite that is generated from the reaction of NO with the superoxide anion.     

A real options model for the transferability value of telecommunications licenses

Licenses for telecommunications services are awarded with a number of side obligations and commitments for the licensee. Under such obligations the licensee is typically not allowed to transfer its license to another operator. Such prohibition may cause heavy inconveniences for customers, so that its removal is strongly advocated and already a reality in many cases. Its removal adds value to the original license and may then constitute a valuable option (the transferability option). A method is here proposed to assess such value, by using the framework of real options. The method is applied in a variety of settings and shows that the value of the option depends superlinearly on the reselling price and the market volatility, and linearly or sub-linearly on the expiry time of the option.