Surface characterization of the hydroxy-terminated poly(∈-caprolactone)/poly(dimethylsiloxane) triblock copolymers by electron spectroscopy for chemical analysis and contact angle measurements

The surface composition and free energy properties of two grades of amphiphilic and semicrystalline triblock copolymers consisting of a poly(dimethylsiloxane) (PDMS) midblock (Mw ≃ 2300) coupled to poly(∈-caprolactone) (PCL) end blocks having differing molecular weights (Mw ≃ 2000, sample P3, and Mw ≃ 3000, sample P2) and homopolymer PCL (Mw ∼ 40 000) were investigated by Fourier transform infrared, spectroscopy, electron spectroscopy for chemical analysis (ESCA), and contact angle measurements using critical surface tension, one-liquid and two-liquid methods. ESCA showed that the molar concentration of PDMS increased from 36.5% in the bulk up to 70.2% in the surface for sample P2 and from 46.3% in the bulk up to 79.2% in the surface for sample P3 in high vacuum. This indicates that the lower surface energy PDMS microdomains were segregated in the surface region to minimize the surface energy of the copolymer. The longer the PCL block, the higher the phase separation. One-liquid contact angle results were evaluated by using van Oss, Good, and Chaudhury's Lifshitz-van der Waals and Lewis acid-base (AB) methodology, and it was determined that the basicity surface tension coefficients (γs-) of the copolymers decreased with the increase of the PDMS content at the surface, a result in agreement with the ESCA results but not proportional to them, indicating that the surfaces of the copolymers are highly mobile and molecular rearrangement takes place upon contacting with a polar testing liquid drop. The strong AB interaction between the basic carboxyl groups of PCL segments with the Lewis acidic groups of the polar liquids restructured the surface molecular composition at the contact area by increasing PCL and decreasing PDMS concentration in polar environments. The two-liquid contact angle method was also applied, and it was determined that γs- decreased inverse proportionally with the increase of PDMS segments. Also, it was realized that the molecular restructuring did not take place in the two-liquid method

Structural and Electronic Decoupling of C_(60) from Epitaxial Graphene on SiC

We have investigated the initial stages of growth and the electronic structure of C_(60) molecules on graphene grown epitaxially on SiC(0001) at the single-molecule level using cryogenic ultrahigh vacuum scanning tunneling microscopy and spectroscopy. We observe that the first layer of C_(60) molecules self-assembles into a well-ordered, close-packed arrangement on graphene upon molecular deposition at room temperature while exhibiting a subtle C_(60) superlattice. We measure a highest occupied molecular orbital–lowest unoccupied molecular orbital gap of ~ 3.5 eV for the C_(60) molecules on graphene in submonolayer regime, indicating a significantly smaller amount of charge transfer from the graphene to C_(60) and substrate-induced screening as compared to C_(60) adsorbed on metallic substrates. Our results have important implications for the use of graphene for future device applications that require electronic decoupling between functional molecular adsorbates and substrates

Vitamin C Enhances Vitamin E Status and Reduces Oxidative Stress Indicators in Sea Bass Larvae Fed High DHA Microdiets

Docosahexaenoic acid (DHA) is an essential fatty acid necessary for many biochemical, cellular and physiological functions in fish. However, high dietary levels of DHA increase free radical injury in sea bass (Dicentrarchus labrax) larvae muscle, even when vitamin E (α-tocopherol, α-TOH) is increased. Therefore, the inclusion of other nutrients with complementary antioxidant functions, such as vitamin C (ascorbic acid, vitC), could further contribute to prevent these lesions. The objective of the present study was to determine the effect of vitC inclusion (3,600 mg/kg) in high DHA (5 % DW) and α-TOH (3,000 mg/kg) microdiets (diets 5/3,000 and 5/3,000 + vitC) in comparison to a control diet (1 % DHA DW and 1,500 mg/kg of α-TOH; diet 1/1,500) on sea bass larvae growth, survival, whole body biochemical composition and thiobarbituric acid reactive substances (TBARS) content, muscle morphology, skeletal deformities and antioxidant enzymes, insulin-like growth factors (IGFs) and myosin expression (MyHC). Larvae fed diet 1/1,500 showed the best performance in terms of total length, incidence of muscular lesions and ossification degree. IGFs gene expression was elevated in 5/3,000 diet larvae, suggesting an increased muscle mitogenesis that was confirmed by the increase in the mRNA copies of MyHC. vitC effectively controlled oxidative damages in muscle, increased α-TOH larval contents and reduced TBARS content and the occurrence of skull deformities. The results of the present study showed the antioxidant synergism between vitamins E and C when high contents of DHA are included in sea bass larvae diets

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Hg 5d and 6s: Multichannel quantum-defect analysis of experimental data

Schäfers F, Heckenkamp C, Müller M, Radojevic V, Heinzmann U. Hg 5d and 6s: Multichannel quantum-defect analysis of experimental data. Physical Review, A: Atomic, Molecular and Optical Physics. 1990;42(5):2603-2613.Experimental spin-polarization data for the Hg 6s Cooper minimum and dipole-transition amplitudes and phase-shift differences for photoionization of the Hg 5d and 6s shells (eight channels) in the photon-energy region from the 2D3/2 threshold up to 35 eV (kinetic energies from 0 to 20 eV) are presented and compared with new relativistic random-phase approximation calculations. The data were evaluated from an experimental data set, quantum mechanically complete, consisting of cross-section and photoelectron spin-polarization data. For the 5d subshells the results show strong interchannel coupling between the outgoing p and f continuum channels. The results for Hg 6s could be used for an independent determination of the photoelectron angular distribution parameter [Beta] in the Cooper-minimum region. This region is shown to be perturbed by numerous two-electron excitations, which might be a possible explanation for the controversy on its location