An innovative, fast and facile soft-template approach for the fabrication of porous PDMS for oil-water separation

Oil wastewater and spilled oil caused serious environmental pollution and damage to public health in the last years. Therefore, considerable efforts are made to develop sorbent materials able to separate oil from water with high selectivity and sorption capacity. However most of them are low reusable, with low volume absorption capacity and poor mechanical properties. Moreover, the synthesis is time-consuming, complex and expensive limiting its practical application in case of emergency. Here we propose an innovative approach for the fabrication of porous PDMS starting from an inverse water-in-silicone procedure able to selectively collect oil from water in few seconds. The synthesis is dramatically faster than previous approaches, permitting the fabrication of the material in few minutes independently from the dimension of the sponges. The porous material evidenced a higher volume sorption capacity with respect to other materials already proposed for oil sorption from water and excellent mechanical and reusability properties.This innovative fast and simple approach can be successful in case of emergency, as oil spill accidents, permitting in situ fabrication of porous absorbents

Reconstructing blockages in a symmetric duct via quasi-isospectral horn operators

This paper proposes a new method for the reconstruction of the blockage area function in a symmetric duct by resonant frequencies under a given set of end conditions, i.e., open open or closed-closed ends. The analysis is based on the explicit determination of quasi-isospectral ducts, that is duct profiles which have the same spectrum as a given duct with the exception of a single eigenfrequency which is free to move in a prescribed interval. The analytical reconstruction was numerically implemented and tested for the detection of blockages. Numerical results show that the accuracy of identification increases with the number of eigenfrequencies used and that the reconstruction is rather stable with respect to the shape, the size and the position of the blockages

Self-assembly in surfactant-based mixtures driven by acid–base reactions: bis(2-ethylhexyl) phosphoric acid– n-octylamine systems

Structural and dynamic features of bis(2-ethylhexyl) phosphoric acid (HDEHP)–n-octylamine (NOA) mixtures as a function of the NOA mole fraction (XNOA) have been investigated by SAXS, WAXS, IR, dielectric spectroscopy and polarized optical microscopy. In the 0 ¡ XNOA , 0.5 range, mixtures are transparent liquids, while the abrupt formation of a waxy solid characterized by an hexagonal bidimensional structure occurs at XNOA = 0.5. Such a composition-induced phase transition results from the synergetic effect of the progressive increase in number density of ordered HDEHP–NOA nanodomains with XNOA. Mainly driven by an HDEHP to NOA proton transfer, the increase of structural order with XNOA arises from the progressive substitution of loosely hydrogen bonded HDEHP–HDEHP aggregates with strongly bonded NOA–HDEHP ones. Analysis of SAXS patterns at temperatures in the 10–70 uC range emphasized that these local structures are scarcely impacted by an increase of thermal fluctuations. Effects due to the steric compatibility between HDEHP and NOA apolar moieties have been highlighted. Overall, the results allow us to emphasize the role of specific polar and apolar interactions joined to steric effects in regulating the molecular organization in surfactant mixtures and can be used to design novel materials with planned physico-chemical properties

An assessment of the effect of supersonic aircraft operations on the stratospheric ozone content

An assessment of the potential effect on stratospheric ozone of an advanced supersonic transport operations is presented. This assessment, which was undertaken because of NASA's desire for an up-to-date evaluation to guide programs for the development of supersonic technology and improved aircraft engine designs, uses the most recent chemical reaction rate data. From the results of the present assessment it would appear that realistic fleet sizes should not cause concern with regard to the depletion of the total ozone overburden. For example, the NOx emission of one type designed to cruise at 20 km altitude will cause the ozone overburden to increase by 0.03% to 0.12%, depending upon which vertical transport is used. These ozone changes can be compared with the predictions of a 1.74% ozone decrease (for 100 Large SST's flying at 20 km) made in 1974 by the FAA's Climatic Impact Assessment Program

The interaction of native calf thymus DNA with FeIII-dipyrido[3,2-a:2\u2019,3\u2019-c]phenazine

The mono and bis dipyrido[3,2-a:20,30-c]phenazine (dppz) adducts of iron(III) chloride, i.e. [Fe(dppz)]Cl3 and [Fe(dppz)2]Cl3, have been synthesized and characterized. The interaction of the FeIIIdppz hydrolyzed aquo complex with native calf thymus DNA has been monitored as a function of the metal complex\u2013DNA molar ratio, by variable temperature UV absorption spectrophotometry, circular dichroism (CD) and fluorescence spectroscopy. The results obtained in solution at various ionic strength values give support for a tight intercalative binding of the FeIIIdppz cation with DNA. In particular, the appearance of induced CD bands, caused by the addition of FeIIIdppz, indicate the existence of a rigid metal complex\u2013DNA-binding leading to dominating chiral organization of FeIIIdppz species within the DNA double helix. The trend of selected CD bands with the molar concentration of FeIIIdppz emphasizes that the presence of high amounts of metal complex induces also the formation of DNA\u2013FeIIIdppz supramolecular aggregates in solution. The analysis of fluorescence measurements allowed us to calculate a value of the intercalative binding constant comparable to that obtained by UV spectrophotometric titration. Finally, the temperature dependence of the absorbance at 258 nm shows that the metal complex strongly increases the DNA melting temperature already at metal complex\u2013DNA molar ratio equal to 0.25 suggesting that metal complex intercalation effectively hinders DNA denaturation. Overall, the results of the present study point out that the FeIIIdppz aquo complex has DNA-binding properties analogous to those previously reported for the tris-chelate FeII(phen)2dppz complex (phen = 1,10-phenantroline)

Environmental effects of SPS: The middle atmosphere

The heavy lift launch vehicle associated with the solar power satellite (SPS) would deposit in the upper atmosphere exhaust and reentry products which could modify the composition of the stratosphere, mesosphere, and lower ionosphere. In order to assess such effects, atmospheric model simulations were performed, especially considering a geographic zone centered at the launch and reentry latitudes