A Lipid-Bilayer-On-A-Cup Device for Pumpless Sample Exchange.

Lipid-bilayer devices have been studied for on-site sensors in the fields of diagnosis, food and environmental monitoring, and safety/security inspection. In this paper, we propose a lipid-bilayer-on-a-cup device for serial sample measurements using a pumpless solution exchange procedure. The device consists of a millimeter-scale cylindrical cup with vertical slits which is designed to steadily hold an aqueous solution and exchange the sample by simply fusing and splitting the solution with an external solution. The slit design was experimentally determined by the capabilities of both the retention and exchange of the solution. Using the optimized slit, a planar lipid bilayer was reconstituted with a nanopore protein at a microaperture allocated to the bottom of the cup, and the device was connected to a portable amplifier. The solution exchangeability was demonstrated by observing the dilution process of a blocker molecule of the nanopore dissolved in the cup. The pumpless solution exchange by the proposed cup-like device presents potential as a lipid-bilayer system for portable sensing applications.

Efficient Decarbonylation of Furfural to Furan Catalyzed by Zirconia-Supported Palladium Clusters with Low Atomicity.

Decarbonylation of furfural to furan was efficiently catalyzed by ZrO2 -supported Pd clusters in the liquid phase under a N2 atmosphere without additives. Although Pd/C and Pd/Al2 O3 have frequently been used for decarbonylation, Pd/ZrO2 exhibited superior catalytic performance compared with these conventional catalysts. Transmission electron microscopy and X-ray absorption fine structure measurements revealed that the size of the Pd particles decreased with an increase in the specific surface area of ZrO2 . ZrO2 with a high surface area immobilized Pd as clusters consisting of several (three to five) Pd atoms, whereas Pd aggregated to form nanoparticles on other supports such as carbon and Al2 O3 despite their high surface areas. The catalytic activity of Pd/ZrO2 was enhanced with a decrease in particle size, and the smallest Pd/ZrO2 was the most active catalyst for decarbonylation. When CeO2 was used as the support, a decrease in Pd particle size with an increase in surface area was also observed. Single Pd atoms were deposited on CeO2 with a high surface area, with a strong interaction through the formation of a Pd-O-Ce bond, which led to a lower catalytic activity than that of Pd/ZrO2 . This result suggests that zero-valent small Pd clusters consisting of more than one Pd atom are the active species for the decarbonylation reaction. Recycling tests proved that Pd/ZrO2 maintained its catalytic activity until its sixth use.

Stability of the microdroplets for portable biosensor.

This paper highlights the behavior of microdroplets used for portable biosensors. Microdroplets have been applied for various Lab-on-a-chip applications, in which portability/wearable is becoming a trend word. However, the resonance (sloshing phenomena) of the microdroplets could be an issue. For example, bilayer lipid membrane, fragile characteristics due to its thickness of 5 nm, easily ruptures by jiggling. We therefore prepared various dimensions of droplets by changing the well shape, and examined the resulting waves depending on the vibration frequency between 20 and 100 Hz, including daily life frequencies. Moreover, we investigated an influence of surface coating of the wells by the same tests. The results of the first examination showed that the sloshing was effectively suppressed by reducing the well length along the vibration axis. We also found that the sloshing was suppressed by reducing surface energy of the microwells. We succeeded in clarifying the characteristics of microdroplets at the vibration in daily life frequency, which will be useful information for development of portable biosensors.

Carbonaceous aerosol tracers in ice-cores record multi-decadal climate oscillations.

Carbonaceous aerosols influence the climate via direct and indirect effects on radiative balance. However, the factors controlling the emissions, transport and role of carbonaceous aerosols in the climate system are highly uncertain. Here we investigate organic tracers in ice cores from Greenland and Kamchatka and find that, throughout the period covered by the records (1550 to 2000 CE), the concentrations and composition of biomass burning-, soil bacterial- and plant wax- tracers correspond to Arctic and regional temperatures as well as the warm season Arctic Oscillation (AO) over multi-decadal time-scales. Specifically, order of magnitude decreases (increases) in abundances of ice-core organic tracers, likely representing significant decreases (increases) in the atmospheric loading of carbonaceous aerosols, occur during colder (warmer) phases in the high latitudinal Northern Hemisphere. This raises questions about causality and possible carbonaceous aerosol feedback mechanisms. Our work opens new avenues for ice core research. Translating concentrations of organic tracers (µg/kg-ice or TOC) from ice-cores, into estimates of the atmospheric loading of carbonaceous aerosols (µg/m(3)) combined with new model constraints on the strength and sign of climate forcing by carbonaceous aerosols should be a priority for future research.

Pd-catalyzed aerobic oxidative coupling of arenes: evidence for transmetalation between two Pd(II)-aryl intermediates.

Pd-catalyzed aerobic oxidative coupling of arenes provides efficient access to biaryl compounds. The biaryl product forms via C-H activation of two arenes to afford a Pd(II)ArAr' intermediate, which then undergoes C-C reductive elimination. The key Pd(II)ArAr' intermediate could form via a "monometallic" pathway involving sequential C-H activation at a single Pd(II) center, or via a "bimetallic" pathway involving parallel C-H activation at separate Pd(II) centers, followed by a transmetalation step between two Pd(II)-aryl intermediates. Here, we investigate the oxidative coupling of o-xylene catalyzed by a PdX2/2-fluoropyridine catalyst (X = trifluoroacetate, acetate). Kinetic studies, H/D exchange experiments, and kinetic isotope effects provide clear support for a bimetallic/transmetalation mechanism.

Palladium-catalyzed aerobic dehydrogenation of substituted cyclohexanones to phenols.

Aromatic molecules are key constituents of many pharmaceuticals, electronic materials, and commodity plastics. The utility of these molecules directly reflects the identity and pattern of substituents on the aromatic ring. Here, we report a palladium(II) catalyst system, incorporating an unconventional ortho-dimethylaminopyridine ligand, for the conversion of substituted cyclohexanones to the corresponding phenols. The reaction proceeds via successive dehydrogenation of two saturated carbon-carbon bonds of the six-membered ring and uses molecular oxygen as the hydrogen acceptor. This reactivity demonstrates a versatile and efficient strategy for the synthesis of substituted aromatic molecules with fundamentally different selectivity constraints from the numerous known synthetic methods that rely on substitution of a preexisting aromatic ring.

Aerobic Oxidative Coupling of o-Xylene: Discovery of 2-Fluoropyridine as a Ligand to Support Selective Pd-Catalyzed C-H Functionalization.

An improved method for direct oxidative coupling of o-xylene could provide streamlined access to an important monomer used in polyimide resins. The use of 2-fluoropyridine as a ligand has been found to enable unprecedented levels of chemo- and regioselectivity in this Pd-catalyzed aerobic oxidative coupling reaction. Preliminary insights have been obtained into the origin of the effectiveness of 2-fluoropyridine as a ligand.