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Enzymatic degradation of p-chlorophenol was carried out in a two-phase flow in a microchannel (100 microm width, 25 microm depth) fabricated on a glass plate (70 mm x 38 mm). This is the first report on the enzymatic reaction in a two-phase flow on a microfluidic device. The surface of the microchannel was partially modified with octadecylsilane groups to be hydrophobic, thus allowing clear phase separation at the end-junction of the microchannel. The enzyme (laccase), which is surface active, was solubilized in a succinic aqueous buffer and the substrate (p-chlorophenol) was in isooctane. The degradation of p-chlorophenol occurred mainly at the aqueous-organic interface in the microchannel. We investigated the effects of flow velocity and microchannel shape on the enzymatic degradation of p-chlorophenol. Assuming that diffusion of the substrate (p-chlorophenol) is the rate-limiting step in the enzymatic degradation of p-chlorophenol in the microchannel, we proposed a simple theoretical model for the degradation in the microchannel. The calculated degradation values agreed well with the experimental data.

Development of a reliable platform and workflow to detect and capture a small number of mutation-bearing circulating tumor cells (CTCs) from a blood sample is necessary for the development of noninvasive cancer diagnosis. In this preclinical study, we aimed to develop a capture system for molecular characterization of single CTCs based on high-density dielectrophoretic microwell array technology. Spike-in experiments using lung cancer cell lines were conducted. The microwell array was used to capture spiked cancer cells, and captured single cells were subjected to whole genome amplification followed by sequencing. A high detection rate (70.2%–90.0%) and excellent linear performance (R2 = 0.8189–0.9999) were noted between the observed and expected numbers of tumor cells. The detection rate was markedly higher than that obtained using the CellSearch system in a blinded manner, suggesting the superior sensitivity of our system in detecting EpCAM− tumor cells. Isolation of single captured tumor cells, followed by detection of EGFR mutations, was achieved using Sanger sequencing. Using a microwell array, we established an efficient and convenient platform for the capture and characterization of single CTCs. The results of a proof-of-principle preclinical study indicated that this platform has potential for the molecular characterization of captured CTCs from patients.

The amount and profile of the charge distribution in a polymethyl methacrylate plate of 7.9-mm thickness were measured after electron beam irradiation. When the plate was irradiated by a beam whose energy was 1 MeV and the total dose was 3 kGy, a spatial charged layer was produced at approximately 2.5 mm from the irradiated side. The maximum charge density was 1.7 μC/cm3 . The charges of the irradiated side decayed faster than the charges which accumulated at positions further away from the irradiated side in the specimen. Computer simulations were carried out to study the charge decay phenomena, assuming that shallow trap levels were created at the irradiated side by the electron beam. The time dependence of the accumulated charge distribution agreed well with the experimental results.

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In the NiAs-type Nil _ x Mx S (M: the 3d transition metal impurities), the solubility limits XL are determined to be 0.077 ± 0.005 for M:Ti, 0.04 ± 0.01 for M:Cr, 0.001 ± 0.002 for M:Mn, 0.060 ± 0.005 for M:Co, and 0.015 ± 0.005 for M:Cu. The first-order transition temperature T, (between the antiferromagnetic less-conductive and the Pauli-paramagnetic high-conductive states) is investigated as a function of X for M:Ti, Cr, Co, and Cu (as described on M:V in our previous paper). The lattice parameters c and a are also investigated. The larger x gives the lower T, for these M, except in the lower x for M:V or Cr. The following features are found on M:Ti (similar to V and Cr): a Curie-Weiss-type susceptibility is superimposed on the constant Pauliparamagnetic one in temperatures above T,; the sign of dO (T < T t )I dT (0: thermoelectric motive force) changes from plus to minus at a critical concentration. The ratio c/ a hardly depends on x in the cases of more than half filJed M (Co and CuI, while it increases in x in the less than half filled M (Ti, V, and Cr). Correlations between these experimental results and the nuclear charges of M atoms or the exchange splitting energies of M(3s) bands in MS compounds are discussed on the basis of the Friedel-type dilute-alloy model. It is additionally noted that Nio.96 CO O . 04 S exhibits an anomalous temperature behavior of susceptibility just above T,. This behavior indicates the presence of an intermediate state, between the above two magnetic states, in the high x region for M:Co.

Articles you may be interested inImpurity effects of the 3d transition metal atoms on the firstorder magnetic and electrical transition in NiS

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