A biosensor in the time domain based on the diffusion coefficient measurement: intermolecular interaction of an intermediate of photoactive yellow protein

A new type of biosensor is presented for the first time. This method is based on the diffusion measurement in the time domain by the transient grating method. As the first demonstration of this new method, various intermolecular interactions with a reaction intermediate of photoactive yellow protein, such as the protein-protein interaction, protein-DNA interaction, and protein-small molecule binding are detected. The characteristic advantages and limitations are summarized.     

Ion exchange of intercalation compounds from WOP2O7 and intercalation ofn-alkylamines

Ion exchange of Na _x WOP₂O₇ ·nH₂O (x 1.4) prepared from WOP₂O₇ was attempted, using alkaline and alkaline earth ions. The degree of exchange was observed to be >50% at 90° C except for Mg²⁺. The basal spacing of ion-exchanged materials for the hydrated phase were dependent on the number of water molecules in the interlayer spaces, while those for the dehydrated phase increased with the size of ions in the interlayer spaces. The network of water molecules linked by the hydrogen bond in the interlayer spaces seems to determine the basal spacing. By the ion-exchange reaction,n-alkylammonium ions were intercalated into the interlayer spaces of Na _x WOP₂O₇ ·nH₂O (x 1.4) and Sn _x H _y WOP₂O₇ ·nH₂O (2x +y 0.5). In spite of the difference in the charge density of the host layer, a similar arrangement of alkyl chains in the interlayer spaces resulted, and neutral amines were considered to be intercalated as well as ammonium ions. Direct reaction ofn-alkylamine with WOP₂O₇ produced an intercalation compound without reduction of tungsten. The arrangement of the amines in the interlayer spaces is similar to that supposed to the ion-exchanged derivatives when heated at 140° Cin vacuo.     

Studies on toxicity of multi-walled carbon nanotubes on Arabidopsis T87 suspension cells

The possible toxicities of agglomerates of multi-walled carbon nanotubes (MWCNTs) toward plant cells were evaluated. Arabidopsis T87 suspension cells were used as the model cells and decreases in values of cell dry weights, cell viabilities, cell chlorophyll contents, and superoxide dismutase (SOD) activities were seen for the cells cultured in media containing the agglomerates of MWCNTs, indicating the agglomerates of MWCNTs are toxic to the Arabidopsis T87 suspension cells. Moreover, the toxicities increased sharply as the diameters of the agglomerates of the MWCNTs became smaller. A concept based on the hypersensitive response is suggested to explain the possible toxic mechanism induced by the MWCNTs.     

Delamination growth mechanisms in woven glass fiber reinforced polymer composites under Mode II fatigue loading at cryogenic temperatures

The purpose of this research is to characterize the cryogenic delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates subjected to Mode II fatigue loading. Mode II fatigue delamination tests were performed at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K) using the four-point bend end-notched flexure (4ENF) test method, and the delamination growth rate data for the woven GFRP laminates were obtained. The energy release rate range was determined by the finite element method. Microscopic examinations of the specimen sections and fracture surfaces were also carried out. The present results are discussed to obtain an understanding of the fatigue delamination growth mechanisms in the woven GFRP laminates under Mode II loading at cryogenic temperatures.     

Mechanochemical decomposition of PVC by using La2O3 as additive

A polyvinyl chloride (PVC, [CH2CHCl]n) sample was ground with one of the following oxide samples, lanthanum oxide (La2O3) and calcium oxide (CaO), as a reference, to investigate its mechanochemical (MC) decomposition. According to the XRD patterns for the ground products, peaks of lanthanum oxy-chloride, LaOCl which is water insoluble, were observed to appear in the patterns of the mixture samples at a molar ratio of (PVC: La2O3 = 1:2) and (1:4), after 20 min grinding, while the patterns of the ground PVC-CaO mixtures show the formation of CaOHCl, which is water soluble, in the products after 2 h grinding. TG patterns taken for the PVC-La2O3 mixtures ground for different periods of time do not indicate significant weight loss in the range from 200 to 300 degrees C, and this suggests that La2O3 is more effective additive than CaO in the MC decomposition for PVC. FT-IR patterns for organic phases in the ground mixture show the reduction of CCl bindings in the PVC structure. The MC reaction between PVC and La2O3 is accompanied by the formation of C-O single bonds, to form LaOCl, which is insoluble in water at ambient condition. This is the reason why the yield of Cl extracted by the water leaching reaches only less than 50%, while it reaches almost 100% in the yield of Cl from the PVC-CaO mixture ground for 2 h or more.     

Preparation of meixnerite (Mg–Al–OH) type layered double hydroxide by a mechanochemical route

We have attempted to synthesize the meixnerite (Mg–Al–OH) type layered double hydroxide (LDH) by a two step milling operation of a mixture of Mg(OH)₂ and Al(OH)₃ with water. In the first-step, a mixture of the starting materials was milled for 1 h without water, and the product prepared in the first-step was milled for 2 h with water in the second-step milling operation. The milled products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermo gravimetric-differential thermal analyses with mass spectroscopy (TG-DTA/MS). The surface morphology was characterized by scanning electron microscopy (SEM). Meixnerite with a small amount of carbonate was successfully synthesized mechanochemically at ambient conditions by milling for only 3 h in a planetary ball mill.     

Integration of multianalyte sensing functions on a capillary-assembled microchip: simultaneous determination of ion concentrations and enzymatic activities by a "drop-and-sip" technique

A general and simple implementation of simultaneous multiparametric sensing in a single microchip is presented by using a capillary-assembled microchip (CAs-CHIP) integrated with the plural different reagent-release capillaries (RRCs), acting as various biochemical sensors. A novel "drop-and-sip" technique of fluid handling is performed with a microliter droplet of a model sample solution containing proteases (trypsin, chymotrypsin, thrombin, elastase) and divalent cations (Ca2+, Zn2+, Mg2+) that passes through the microchannel with the aid of a micropipette as a vacuum pump, concurrently filling each RRC via capillary force. To avert the evaporation of the nanoliter sample volume in each capillary, PDMS oil is dropped on the outlet hole of the CAs-CHIP exploiting the capillary force that results in spontaneous sealing of all the RRCs. In addition, this high-speed sample introduction alleviates the possibility of protein adsorption and capillary cross-contamination, allowing a reliable and multianalyte determination of a sample containing many different proteases and divalent cations by using the fluorescence image analysis. Presented results suggested the possible application of this microchip in the field of drug discovery and systems biology.     

Effects of electric field and poling on the mode I energy release rate in cracked piezoelectric ceramics at cryogenic temperatures

We discuss the mode I energy release rate of a rectangular piezoelectric material with a crack under electromechanical loading at cryogenic temperatures. A crack was created normal or parallel to the poling direction, and electric fields were applied parallel or normal to the poling. A plane strain finite element analysis was carried out, and the effects of electric field and localized polarization switching on the energy release rate were discussed for the piezoelectric ceramics at cryogenic temperatures.     

Preparation of pyrochlores. A1−xHxTaO3·nH2O (A=Na,K)

Pyrochlores of A_1?xH_xTaO₃·nH₂O (A=Na,K) were prepared under the hydrothermal conditions. The values of x for these compounds were increased from 0.3 to 0.5 for A=Na and from 0.2 to 0.5 for A=K by treatment with the distilled water. The compounds with x<0.5 were decomposed to a mixture of NaTaO₃ and Na₂Ta₄O₁₁ for A=Na, or to a mixture of KTaO₃ and a tetragonal tungsten bronze phase, and those with x=0.5 to a single phase of A₂Ta₄O₁₁ at elevated temperatures. Below the decomposition temperatures, defect pyrochlores with oxygen vacancies, $\text{A}{}_{\mathrm{<mtext>1?</mtext><mtext>x</mtext>}}\text{TaO}{}_{\mathrm{<mtext>3?</mtext><mtext>x</mtext><mtext>2</mtext>}}$, were produced. They were hygroscopic, and in the case of A=K and x=0.5 the original phase was recovered by leaving in air for several hours.