Urethanes and polyurethanes based on oxypropylated cork: 1. Appraisal and reactivity of products

The reaction of various polyols derived from the oxypropylation of cork with aliphatic and aromatic mono‐ and diisocyanates was studied in solution at room temperature. In all instances, good second‐order kinetics were observed and the corresponding rate constant determined. The reactivity of the aromatic isocyanate was found to be much higher than that of aliphatic counterparts. The ensuing urethanes and polyurethanes were characterised by FTIR and ¹H NMR spectroscopy, DSC and sol/gel distribution. © 2001 Society of Chemical Industry     

Laser‐induced surface structures on gold‐coated polymers: Influence of morphology on surface‐enhanced Raman scattering enhancement

The fabrication of highly sensitive and reproducible substrates for Surface‐Enhanced Raman Scattering (SERS) remains a challenging scientific and technological issue. In this work, laser‐induced periodic surface structures are generated on poly(trimethylen terephthalate) films upon laser irradiation with the linearly polarized beams of a Nd:YAG laser (4th harmonic, 266 nm), an ArF excimer laser (193 nm), and a Titanium:sapphire laser (795 nm), resulting in periods close to the laser wavelength when irradiating at normal incidence, and larger periods for different angles of incidence. Additional irradiation with a circularly polarized beam at 266 nm produces superficial circular structures. The nanostructured polymers are coated with a nanoparticle assembled gold layer by pulsed laser deposition at 213 nm. The capabilities of these substrates for SERS are evaluated using benzenethiol as a test molecule and different degrees of Raman signal enhancement are observed depending on the nanostructure type. The highest enhancement factor is obtained by for nanostructured substrates with the highest values of period, depth, and roughness. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42770.     

Synergistic Effect in Selective Reduction of NO by Alkanes over Mechanically Mixed Oxide Catalysts

The process of selective catalytic reduction of nitrogen oxides by propane in the presence of O₂, as well as in the presence or absence of CO, was studied over series of commercial oxide catalysts used in petrochemical processes. For the first time synergistic effect was observed for catalytic systems consisting of mechanical mixtures of Cu–Zn–Ni–Al (catalyst I) + Fe–Cr (catalyst II) and Cu–Zn–Ni–Al (catalyst I) + Ni–Cr (catalyst III). The activity of these mixtures in nitrogen oxides reduction by propane was greater than that of individual components in each case. The worked-out catalytical systems showed high effectivity in the process of simultaneous removal of several toxic components: NO _x , CO, hydrocarbons – from model gas mixtures, as well as from real exhausts of automotive transport.     

Rheological,Thermodynamic, and Gas Solubility Properties of Phenylacetic Acid‐Based Deep Eutectic Solvents

Choline chloride + phenylacetic acid‐based deep eutectic solvents are studied. Their most relevant experimental physicochemical properties at different mixing ratios together with the CO₂ solubility data obtained in wide pressure and temperature ranges are reported. The presented materials exhibit a significant CO₂ capture performance with low corrosion effect when compared with the most common amine‐based CO₂ capture agents. Detailed rheological measurements are carried out and various models are applied to describe the dynamic flow behavior of the solvents. The CO₂ absorption mechanism is evaluated by studying the behavior of the liquid gas and interface. Due to the advantages of low cost, nontoxicity, and favorable physical properties, these solvents are an environmentally promising alternative for effective CO₂ capture technological applications.     

Highly thermally conductive hexagonal boron nitride/alumina composite made from commercial hexagonal boron nitride

Hexagonal BN is an unusual material in that it is both highly thermally conductive as well as an electrical insulator. Additionally, hBN is also thermally stable in air. This unusual combination of properties makes hBN of significant interest for thermal management. Unfortunately, hBN is not easily consolidated into substrates without the addition of second phases which generally result in poorer thermal performance. This research investigates the potential to utilize this material to dissipate heat from high‐voltage, high‐power electrical devices. Specifically, a process to coat individual platelets of commercial hexagonal BN powder with a layer of amorphous aluminum oxide was developed. The coated hexagonal BN was then hot‐pressed to form a highly thermally conductive substrate. The process to coat hexagonal BN platelets with aluminum oxide was accomplished by mixing hexagonal BN with AlCl₃ containing some water, then evaporation of excess AlCl₃ to form a Al, Cl, and O layer on hexagonal BN. This product was then heated in air to convert the surface layer into aluminum oxide. Following hot pressing to 1950°C and 10 ksi, the consolidated composite has through‐plane and in‐plane thermal conductivity of 14 and 157 W·(m·K)^?1, respectively, at room temperature.     

Study,Mechanical Characterization and Mathematical Modeling of Compatible SEBS Blends for Industrial Applications in Orthopedics and Childcare

In this work, a system of compatible blends based on two commercial grades of a thermoplastic elastomer, styrene-ethylene/butylene-styrene (SEBS), with extreme Shore A hardness values (5 and 90), was studied in order to obtain a range of different performance blends for orthopedic and childcare applications, where usually liquid silicone rubber is used. Mechanical properties of different blends were obtained, and Equivalent Box Model (EBM) was used for the prediction of the mechanical behavior. The results show good agreement between the theoretical model and experimental data of new blends of SEBS.     

Rancidity development during the chilled storage of farmed Coho salmon (Oncorhynchus kisutch)

Coho salmon (Oncorhynchus kisutch) is a fatty fish species whose farming production has greatly increased in recent years. Lipid damage produced during Coho salmon chilled storage was studied for up to 24 d. Lipid hydrolysis (free fatty acids, FFA) and oxidation (conjugated dienes; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compounds formation, FR; browning development) were determined and compared to lipid composition (polyene index, PI; astaxanthin, AX) changes and sensory assessment (rancid odour development) results. Most lipid damage indices developed slowly during storage; thus, values obtained for FFA, PV, TBA‐i and FR were in all cases under 1.5 g/100 g, 4.0 meq oxygen/kg lipid, 0.40 mg malondialdehyde/kg muscle and 0.40, respectively. Odour assessment showed a significant (p <0.05) rancidity development at day 10, when compared to starting fish material; then, non‐acceptable values were obtained at days 19 and 24. The PI analysis showed not many differences during the storage time, with the lowest mean value at day 19. AX analysis indicated a relatively high content in the white muscle, which was maintained till the end of the experiment. A low oxidation development is concluded for Coho salmon lipids when compared to other fatty fish species under the same chilling conditions. AX was found to contribute to the oxidation stability of Coho salmon lipids, due to its free radical scavenger properties.     

Mechanical improvement of concrete by irradiated polypropylene fibers

Fiber reinforced concrete (FRC) contains fibers physically mixed with gravel, sand, cement, and water. So far, adequate mechanical performance of FRC has been obtained at high cost and using complex technologies; important here is the geometry and surface characteristics of the polymers. We have modified polymeric‐fiber surfaces by using gamma radiation. Irradiated polypropylene (PP) fibers were submitted to 0, 5, 10, 50, and 100 kGy of gamma irradiation dosages. First, tensile strength of PP fibers was evaluated, and then fibers blended at 0, 1.0, 1.5, and 2.0% in volume with Portland cement, gravel, sand, and water. The highest values of compressive strength were obtained with irradiated‐fibers at 10 kGy and 1.5% in volume of fiber. The result is 101 MPa, as compared to 35 MPa for simple concrete without fibers. POLYM. ENG. SCI., 45:1426–1431, 2005. © 2005 Society of Plastics Engineers     

Overexpression of microRNAs miR-25-3p,miR-185-5p and miR-132-3p in Late Onset Fetal Growth Restriction,Validation of Results and Study of the Biochemical Pathways Involved

In a prospective study, 48 fetuses were evaluated with Doppler ultrasound after 34 weeks and classified, according to the cerebroplacental ratio (CPR) and estimated fetal weight (EFW), into fetuses with normal growth and fetuses with late-onset fetal growth restriction (LO-FGR). Overexpression of miRNAs from neonatal cord blood belonging to LO-FGR fetuses, was validated by real-time PCR. In addition, functional characterization of overexpressed miRNAs was performed by analyzing overrepresented pathways, gene ontologies, and prioritization of synergistically working miRNAs. Three miRNAs: miR-25-3p, miR-185-5p and miR-132-3p, were significantly overexpressed in cord blood of LO-FGR fetuses. Pathway and gene ontology analysis revealed over-representation of certain molecular pathways associated with cardiac development and neuron death. In addition, prioritization of synergistically working miRNAs highlighted the importance of miR-185-5p and miR-25-3p in cholesterol efflux and starvation responses associated with LO-FGR phenotypes. Evaluation of miR-25-3p; miR-132-3p and miR-185-5p might serve as molecular biomarkers for the diagnosis and management of LO-FGR; improving the understanding of its influence on adult disease.