Structure and gas transport characteristics of triethylene oxide-grafted polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene

Polymeric membrane-based gas separation technology has significant advantages compared with traditional amine-based CO₂ separation method. In this work, SEBS block copolymer is used as a polymer matrix to incorporate triethylene oxide (TEO) functionality. The short ethylene oxide segment is chosen to avoid crystallization, which is confirmed by differential scanning calorimetry and wide-angle X-ray scattering characterizations. The gas permeability results reveal that CO₂/N₂ selectivity increased with increasing content of TEO functional group. The highest CO₂ permeability (281 Barrer) and CO₂/N₂ selectivity (31) were obtained for the membrane with the highest TEO incorporation (57 mol%). Increasing the TEO content in these copolymers results in an increase in CO₂ solubility and a decrease in C₂H₆ solubility. For example, as the grafted TEO content increased from 0 to 57 mol%, the CO₂ solubility and CO₂/C₂H₆ solubility selectivity increased from 0.72 to 1.3 cm³(STP)/cm³ atm and 0.47 to 1.3 at 35°C, respectively. The polar ether linkage in TEO-grafted SEBS copolymers exhibits favorable interaction with CO₂ and unfavorable interaction with nonpolar C₂H₆, thus enhancing CO₂/C₂H₆ solubility selectivity.     

Solution structure of copper-seamed C-alkylpyrogallol[4]arene nanocapsules with varying chain lengths

The stability of copper-seamed C-alkylpyrogallol[4]arene hexamers with varying chain lengths in solution has been studied using small-angle neutron scattering (SANS). The progression in diameter of spherical capsules with increasing alkyl chain lengths of copper-seamed hexamers in solution suggests both robustness as well as a close correlation between the solid phase and solution phase structures.     

Germaindacenodithiophene based low band gap polymers for organic solar cells

We report the first synthesis of a fused germaindacenodithiophene monomer and its polymerisation with 2,1,3-benzothiadiazole by Suzuki polycondensation. The resulting polymer, PGeTPTBT, is semicrystalline, despite the presence of four bulky 2-ethylhexyl groups. Blends with P(70)CBM afford solar cells with efficiencies of 5.02%.     

A theoretical model of oscillatory blood flow in arteries

Wave propagation within a thick-walled, compressible, viscoelastic tube containing a polar fluid is studied as a model of oscillatory blood flow in arteries. Describing blood rheology using polar fluid theory allows one to take into account dissipative effects arising from hydrodynamic interactions between red cells. The phase velocity ratio, transmission per wavelength and hydraulic fluid impedance are determined as a function of the frequency parameter for various specified values of fluid and tube parameters. Hydrodynamic interactions between red cells are found to reduce significantly the transmission per wavelength. Futher, it is found that the marked increase in fluid resistance with increasing frequency which is observed experimentally is due, in part, to the dissipative effects of cell-cell interactions.     

Matrix characterization of oscillation for double sequences

The notion of oscillation for ordinary sequences was presented by Hurwitz in 1930. Using this notion Agnew and Hurwitz presented regular matrix characterization of the resulting sequence space. The primary goal of this article is to extend this definition to double sequences, which grants us the following definition: the double oscillation of a double sequence of real or complex number is given P-lim sup_{(m,n)→∞;(α,β)→∞}|S _m,n -S _α,β |. Using this concept a matrix characterization of double oscillation sequence space is presented. Other implication and variation shall also be presented.      

An overview of reference materials prepared for standardization of DNA typing procedures

Although DNA typing is an accurate, precise, and robust procedure, quality assurance is enhanced by availability of a suitable reference material. The National Institute of Standards and Technology (NIST) recently released a Standard Reference Material (SRM) that meets the calibration and quality assurance needs of laboratories that perform DNA typing. Each step of the analytical process of DNA typing may be verified by one or more of twenty different components of the SRM. As newer, more sensitive methods for DNA typing have been introduced into the human identification laboratory repertoire, new SRMs will be required for quality assurance. A second SRM for PCR-based tests is under development and soon to be available, is also described.     

Field-induced magnetic form factor of lutetium

The conduction electron field-induced magnetic form factor of Lu, a rare earth metal with a closed 4f shell, has been measured using the polarized neutron technique. The measurements demonstrate that the conduction electron density is more spatially extended than in the free atom. The experimental results are in good agreement with band calculations of the $\text{spin}$ magnetic form factor.     

Temperature dependence of the absorption coefficient of CH2O at the 3.508 μm HeXe laser line

The observed temperature and pressure dependence (for 700?T, °K?2100, 0.44?p, atm?2.7) of the spectral absorption coefficient of formaldehyde at the HeXe laser line at 3.508 μm may be accounted for by assuming that the principal contribution at elevated temperatures is made by an isolated, distant line in the ground vibrational state.     

A study of the reaction p+d → 3He+π0 in the resonance region

The reaction $\text{p}\text{+}\text{d}\text{→}{}^3\text{He}\text{+ π}{}^0$ was studied at incident proton energies of 377, 462 and 576 MeV. A comparison of our data with others suggests the existence of a sharp forward peak in θ_He at 377 and 462 MeV, which is unexplained by the theory and disappears at higher energies.