In-channel electrochemical detection in the middle of microchannel under high electric field

We propose a new method for performing in-channel electrochemical detection under a high electric field using a polyelectrolytic gel salt bridge (PGSB) integrated in the middle of the electrophoretic separation channel. The finely tuned placement of a gold working electrode and the PGSB on an equipotential surface in the microchannel provided highly sensitive electrochemical detection without any deterioration in the separation efficiency or interference of the applied electric field. To assess the working principle, the open circuit potentials between gold working electrodes and the reference electrode at varying distances were measured in the microchannel under electrophoretic fields using an electrically isolated potentiostat. In addition, "in-channel" cyclic voltammetry confirmed the feasibility of electrochemical detection under various strengths of electric fields (～400 V/cm). Effective separation on a microchip equipped with a PGSB under high electric fields was demonstrated for the electrochemical detection of biological compounds such as dopamine and catechol. The proposed "in-channel" electrochemical detection under a high electric field enables wider electrochemical detection applications in microchip electrophoresis.     

A CAWL handler for context-aware composite workflow services

In distributed computing environment,workflow technologies have been continuously developed.Recently,there is an attempt to apply these technologies to context-aware services in ubiquitous computing environment.The middleware,which offers services in such environments,should support the automation services suited for the user using various types of situational information around the user.In this paper,based on context-aware workflow language （CAWL）,we propose a CAWL based composite workflow handler for supporting composite workflow services,which can integrate more than two service flows and handle them.The test results shows that the proposed CAWL handler can provide the user with the composite workflow services to cope with various demands on a basis of a scenario document founded on CAWL.     

Droplet generation with integrated 3D pneumatic actuator for orifice control

A droplet generator with an embedded 3D balloon actuator around a flow-focusing junction is realized to adjust the size of the droplets as required with only one element. The 3D actuator encircling the orifice causes a geometric deformation due to pneumatic pressure, which controls the orifice and thus the sizes of the droplets. The orifice and actuator are designed to have triangular cross-sections with the largest possible reduction in hydraulic diameters under the same pneumatic pressure. We empirically demonstrated that, compared with typical fixed orifice structures, droplet generators with variable orifices reduce the droplet size without changing the flow rate and can even be adjusted to a wider range of 259.3 %. The devices were fabricated by the 3D-printed soluble mold technique to achieve a fully 3D structure within a single body of polydimethylsiloxane that is unattainable by conventional standard microfabrications as well as a non-bonding structure without any leakage.

     

Grain accumulation of selenium species in rice (Oryza sativa L.)

Efficient Se biofortification programs require a thorough understanding of the accumulation and distribution of Se species within the rice grain. Therefore, the translocation of Se species to the filling grain and their spatial unloading were investigated. Se species were supplied via cut flag leaves of intact plants and excised panicle stems subjected to a ± stem-girdling treatment during grain fill. Total Se concentrations in the flag leaves and grain were quantified by inductively coupled plasma mass spectrometry. Spatial accumulation was investigated using synchrotron X-ray fluorescence microtomography. Selenomethionine (SeMet) and selenomethylcysteine (SeMeSeCys) were transported to the grain more efficiently than selenite and selenate. SeMet and SeMeSeCys were translocated exclusively via the phloem, while inorganic Se was transported via both the phloem and xylem. For SeMet- and SeMeSeCys-fed grain, Se dispersed throughout the external grain layers and into the endosperm and, for SeMeSeCys, into the embryo. Selenite was retained at the point of grain entry. These results demonstrate that the organic Se species SeMet and SeMeSeCys are rapidly loaded into the phloem and transported to the grain far more efficiently than inorganic species. Organic Se species are distributed more readily, and extensively, throughout the grain than selenite.     

Patterning Si by using surface functionalization and microcontact printing with a polymeric ink

This paper describes a simple procedure for patterning Si substrate using a combination of surface functionalization and microcontact printing(ΜCP). The Si/SiO₂ surfaces were chemically modified to present self-assembled monolayers (SAMs) of siloxanes terminating in reactive carboxylic anhydride groups and then patterned with poly(ethylene imine) (PEI) by, ΜCP We used the patterned thin films of PEI as etch resists on Si surfaces.     

Distributed lag effects in the relationship between temperature and mortality in three major cities in South Korea

In many cases, the effect of an environmental exposure event is not restricted to the period when it occurs. Understanding the extent to which high-temperature exposure hastens the occurrence of health outcomes is a key to interpreting public health risks correctly and developing appropriate intervention programs related to heat. We explored distributed lag effects in the relationship between high temperature and mortality in summer (June-August) in Seoul, Daegu, and Incheon, South Korea, from 1991 to 2008.A Poisson regression model adapted for time-series data was used to estimate short-term heat-related mortality impacts. To examine the distributed lag effects, we fitted a constrained distributed lag model that included lagged exposure variables as covariates, applying a function of days of lag according to B-spline bases.The effects on mortality caused by high-temperature exposure continued for about 5 days, and slight deficit effects after the initial mortality increases were observed, even if not initially apparent. Thirty days after high-temperature exposure, the cumulative effects were still high in Seoul and Incheon.This study shows a pattern of distributed lag effects of high-temperature exposure that the single-day model could not identify. Our results confirm that summer high temperature has an effect on mortality, not advancing the date of adverse events by a few days. Ultimately, it suggests that public health programs be amended to allow for differential high-temperature effects spread over multiple days.     

Room‐Temperature Ferromagnetic Insulating State in Cation‐Ordered Double‐Perovskite Sr2Fe1+xRe1−xO6Films

Ferromagnetic insulators (FMIs) are one of the most important components in developing dissipationless electronic and spintronic devices. However, FMIs are innately rare to find in nature as ferromagnetism generally accompanies metallicity. Here, novel room‐temperature FMI films that are epitaxially synthesized by deliberate control of the ratio between two B‐site cations in the double perovskite Sr₂Fe_1+xRe_1‐xO₆ (?0.2 ≤ x ≤ 0.2) are reported. In contrast to the known FM metallic phase in stoichiometric Sr₂FeReO₆, an FMI state with a high Curie temperature (T_c ≈ 400 K) and a large saturation magnetization (M_S ≈ 1.8 µ_B f.u.^?1) is found in highly cation‐ordered Fe‐rich phases. The stabilization of the FMI state is attributed to the formation of extra Fe³⁺? Fe³⁺ and Fe³⁺? Re⁶⁺ bonding states, which originate from the relatively excess Fe ions owing to the deficiency in Re ions. The emerging FMI state created by controlling cations in the oxide double perovskites opens the door to developing novel oxide quantum materials and spintronic devices.     

Liquid-phase microextraction as an on-line preconcentration method in capillary electrophoresis

A simple and efficient sample preconcentration method for capillary electrophoresis has been developed using liquid-phase microextraction (LPME). A thin layer of an organic liquid was used to separate a drop of the aqueous acceptor phase hanging at the inlet of a capillary from the bulk aqueous donor phase. The donor-phase pH was 1.0, and the acceptor phase pH was 9.5. This pH difference caused the preconcentration of the acidic compounds, fluorescein and fluorescein isothiocyanate, into the acceptor-phase drop. Enrichment factors of 3 orders of magnitude were obtained with 30-min LPME at 35 degrees C.     

Mechanistic study on Sn(Oct)<Subscript>2</Subscript>-catalyzed,ring-opening polymerization of <Emphasis Type="Italic">p</Emphasis>-dioxanone by surface-initiated polymerization and x-ray photoelectron spectroscopy

Two mechanisms on Sn(Oct)₂-catalyzed, ring-opening polymerization of p-dioxanone (PDX) were mainly proposed: activated monomer mechanism and coordination-insertion mechanism. The activated monomer mechanism assumes that alcohol complexed with Sn(Oct)₂ reacts with monomer and forms a ternary complex. The initiation and chain growth then proceeds within the complex with liberation of the intact Sn(Oct) ₂. In contrast, the coordination-insertion mechanism hypothesizes that an actual initiator is the -Sn(OR) species and the polymerization proceeds on the -Sn-O-polymer. In this paper, to investigate the presence/absence of the Sn species in the PPDX chain, we used X-ray photoelectron spectroscopy (XPS) of poly(p-dioxanone) (PPDX) grown from a gold surface using the grafting-from approach, and the XPS data supports the coordination-insertion mechanism. After the polymerization of PPDX from the surface, the peaks from Sn were observed at 153, 486, and 495 eV in XPS spectrum, and the peaks disappeared after quenching with 1N HCl.