Extreme‐Performance Rubber Nanocomposites for Probing and Excavating Deep Oil Resources Using Multi‐Walled Carbon Nanotubes

The scarcity of oil resources is going to become one of the main factors threatening the stability of the global economy. To avoid an energy crisis in the future, it is essential to increase oil extraction in much deeper wells, experiencing higher temperatures and pressures. Exploring these deeper areas will demand novel and robust materials. Rubber sealants, or O‐rings, are especially key components in enabling the probing and production of oil in deeper wells, so that higher temperature and pressure reservoirs are reached. In this account, it is demonstrated that carbon nanotubes homogeneously and randomly dispersed in rubber matrices, are able to generate durable sealants that operate satisfactorily at extremely high temperatures and pressures (e.g., 260 °C and 239 MPa). The key issues in these novel composites are: i) the nanotube surface‐control and reactivity, ii) the used of multi‐walled carbon nanotubes (MWNTs)‐embedded in fluorinated rubber, and iii) the formation of a cellulation structure. This rubber nanocomposite with a cellulation structure and having extreme performance leads to a balanced pressure resistance, sealing ability, thermal resistance, and durability, which can contribute to doubling the current average global oil recovery efficiency.     

In vitro evaluation of tissue adhesives composed of hydrophobically modified gelatins and disuccinimidyl tartrate

The effect of the hydrophobic group content in gelatin on the bonding strength of novel tissue–penetrating tissue adhesives was evaluated. The hydrophobic groups introduced into gelatin were the saturated hexanoyl, palmitoyl, and stearoyl groups, and the unsaturated oleoyl group. A collagen casing was employed as an adherend to model soft tissue for the in vitro determination of bonding strength of tissue adhesives composed of various hydrophobically modified gelatins and disuccinimidyl tartrate. The adhesive composed of stearoyl-modified gelatin (7.4% stearoyl; 10Ste) and disuccinimidyl tartrate showed the highest bonding strength. The bonding strength of the adhesives decreased as the degree of substitution of the hydrophobic groups increased. Cell culture experiments demonstrated that fluorescein isothiocyanate-labeled 10Ste was integrated onto the surface of smooth muscle cells and showed no cytotoxicity. These results suggest that 10Ste interacted with the hydrophobic domains of collagen casings, such as hydrophobic amino acid residues and cell membranes. Therefore, 10Ste–disuccinimidyl tartrate is a promising adhesive for use in aortic dissection.     

Tensile strain dependence of critical current of RHQ-Nb3Al wires

Nb₃Al superconducting wires produced by rapid heating and quenching (RHQ) have been developed for high-field accelerator magnets. It is known that critical currents of A15 superconductors (e.g., Nb₃Al and Nb₃Sn) have a dependence on stress/strain. It is thus important to clarify the stress/strain behavior of the RHQ-Nb₃Al wires for the development of high-field accelerator magnets. We recently started experimentally investigating the strain dependence of the critical current of the RHQ-Nb₃Al wires with a Ta interfilament by measuring their critical currents under longitudinal tensile strains. To evaluate the effect of residual strain in Nb₃Al filaments induced by thermal contraction of the materials in the wire, neutron diffraction measurements were performed at room temperature.     

Coalesced C60 Molecules in Toluene Under Ultrahigh Pressure

Abstract

We present mass spectral evidence that coalesced C60 dimers and trimers were formed in toluene under 1.2-1.4 GPa at room temperature.     

Clustering triple microbeads in a dynamic microarray for timing-controllable bead-based reactions

In this study, we developed a dynamic microfluidic device that enables the clustering of three different types of microbeads in a trapping spot and the rearrangement of contacting modes of the clustered microbeads. To achieve these two functions, two features are added to the conventional dynamic microfluidic device. (1) To trap multiple beads, an extended trapping spot with sub-by-pass channels and a valve was employed. (2) To rearrange the clustered microbeads, trapping spots that work only by backward flow were added. The design of the microfluidic device was realized by calculations based on fluidic resistance. By using the designed device, we successfully clustered different types of hydrogel microbeads including target materials, and observed reactions between clustered microbeads. In addition, by rearranging the contacting modes of the clustered microbeads, the reaction could be initiated/terminated at the desired time. We found that this dynamic microfluidic device is applicable to the quantitative analysis of chemical reactions between small amounts of multiple materials.     

Highly efficient coupling of photons from nanoemitters into single-mode optical fibers

Highly efficient coupling of photons from nanoemitters into single-mode optical fibers is demonstrated using tapered fibers. A percentage (7.4 ± 1.2%) of the total emitted photons from single CdSe/ZnS nanocrystals were coupled into a 300 nm diameter tapered fiber. The dependence of the coupling efficiency on the taper diameter was investigated and the coupling efficiency was found to increase exponentially with decreasing diameter. This method is very promising for nanoparticle sensing and single-photon sources.