Cytotoxic effect of conjugated trienoic fatty acids on mouse tumor and human monocytic leukemia cells

The cytotoxicity of fatty acids from seed oils containing conjugated linolenic acids (CLN) was studied. Fatty acids from pomegranate, tung, and catalpa were cytotoxic to human monocytic leukemia cells at concentrations exceeding 5 μM for pomegranate and tung and 10 μM for catalpa, but fatty acids from pot marigold oil had no effect at concentrations ranging up to 163 μM. The main conjugated fatty acids of pomegranate, tung, catalpa, and pot marigold were cis(c)9, trans(t)11, c13-CLN (71.7%), c9,t11,t13-CLN (70.1%), t9,t11,c13-CLN (31.3%), and t8,t10,c12-CLN (33.4%), respectively. Therefore, the cytotoxicities of fatty acids from pomegranate, tung, and catalpa were supposed to be due to 9,11,13-CLN isomers. To elucidate the cytotoxicity of these CLN, we separated each CLN isomer from the fatty acid mixtures by high-performance liquid chromatography and analyzed its cytotoxicity. The cytotoxicities of c9,t11,c13-CLN, c9,t11,t13-CLN, and t9,t11,c13-CLN were much stronger than that of t8,t10,c12-CLN. Therefore, the higher cytotoxicity of fatty acids from pomegranate, tung, and catalpa than those from pot marigold would be derived from the different activities of 9,11,13-CLN and 8,10,12-CLN. Since there was little difference in the cytotoxicities of c9,t11,c13-CLN, c9,t11,t13-CLN, and t9,t11,c13-CLN, it is suggested that the cis/trans configuration of 9,11,13-CLN isomers had little effect on their cytotoxic effects. The mechanism of the cytotoxicity of the four fatty acids above may involve lipid peroxidation, because the order of toxicity of the fatty acids was consistent with their susceptibility to peroxidation in aqueous phase. This was supported by the decrease in the cytotoxicity of the fatty acids by addition of butylated hydroxytoluene.     

Comparative study of carbon-supported Pt/Mo-oxide and PtRu for use as CO-tolerant anode catalysts

Carbon-supported Pt/Mo-oxide catalysts were prepared, and the reformate tolerances of Pt/MoOx/C and conventional PtRu/C anodes were examined to clarify the features and differences between these catalysts. Fuel cell performance was evaluated under various reformate compositions and operating conditions, and the CO concentrations at the anode outlet were analyzed simultaneously using on-line gas chromatography. Pt/MoOx showed better CO tolerance than PtRu with CO(80 ppm)/H₂ mixtures, especially at higher fuel utilization conditions, which is mainly due to the higher catalytic activity of Pt/MoOx for the water-gas shift (WGS) reaction and electro-oxidation of CO. In contrast, the CO₂ tolerance of Pt/MoOx was much worse than that of PtRu with a CO₂(20%)/H₂ mixture. The results of voltammetry indicated that the coverage of adsorbates generated by CO₂ reduction on Pt/MoOx was higher than that on PtRu, and therefore, the electro-oxidation of H₂ is partly inhibited on Pt/MoOx in the presence of 20% CO₂. With CO(80 ppm)/CO₂(20%)/H₂, the voltage losses of Pt/MoOx and PtRu are almost equal to the sum of the losses with each contaminant component. Although the adsorbate coverage on Pt/MoOx increases in the presence of 20% CO₂, CO molecules in the gas phase could still adsorb on Pt through an adsorbate ‘hole’ to promote WGS or electro-oxidation reactions, which leads to a reduction in the CO concentration under CO/CO₂/H₂ feeding conditions.     

Application of hydrophobic micropatterns to centrifugal fluid valve in flow channel

Optimizing the use of micro-flow channels as fluid control mechanisms is an effective means of increasing the sensitivity and selectivity of biosensors. The purpose of this study was to clarify the effectiveness of periodic structure applied to this type of fluid control mechanism to improve the hydrophobicity. We evaluated the functionality of centrifugal fluid valve with micrometer-sized periodic structure in the micro-flow channel. A disposable compact disc-based chip with centrifugal fluid valve was designed for this evaluation. The hydrophobic properties such as transferred volume ratio of the sample solution and the change in the transferred volume ratio with rotational velocity (slope) of the centrifugal fluid valve were investigated. In this case, parallel pillars showed higher hydrophobicity than cross-shaped pillars. The transferred volume ratio increased by 20% compared to that without a micro-periodic structure when a protein solution with a similar concentration to that in saliva and plasma was used. Additionally, a change in rotational velocity of only 49.3 rpm was sufficient to switch a centrifugal fluid valve with parallel pillars, meaning that it makes it possible to have two critical rotation speeds when the fluid begins to move with a rotational velocity of 100 rpm. It was shown that the static hydrophobicity dominates the switching characteristics in the proposed centrifugal fluid valve. Our study suggests that applying periodic structure to fluid control mechanisms is an effective means of realizing hydrophobic surfaces.     

Microfluidic counterflow centrifugal elutriation system for sedimentation-based cell separation

We present a centrifugal microfluidic system for precise cell/particle sorting using the concept of counterflow centrifugal elutriation (CCE). A conventional CCE system uses a rotor device incorporating a flow-through separation chamber, in which the balance of centrifugal and counterflow drag forces exerted on particles is gradually shifted by changing the flow rate and/or the rotation speed. In the present system, both the centrifugal and the fluid forces are generated through microdevice rotation in order to significantly simplify the setup of the conventional CCE. In addition, the density gradient of the medium is employed to elute particles/cells of different sedimentation velocities stepwise from the separation chamber instead of changing the rotation speed. We successfully separated polymer particles with diameters of 1.0–5.0 μm using a branched loading channel for focusing particles to the center of the separation chamber. We also demonstrated the sorting of blood cells for biological applications. This system may provide a versatile means for cell/particle sorting in a general biological laboratory and function as a unit operation in various centrifugal microfluidic platforms for biochemical experiments and clinical diagnosis.     

The actor-critic learning is behind the matching law: matching versus optimal behaviors

The ability to make a correct choice of behavior from various options is crucial for animals' survival. The neural basis for the choice of behavior has been attracting growing attention in research on biological and artificial neural systems. Alternative choice tasks with variable ratio (VR) and variable interval (VI) schedules of reinforcement have often been employed in studying decision making by animals and humans. In the VR schedule task, alternative choices are reinforced with different probabilities, and subjects learn to select the behavioral response rewarded more frequently. In the VI schedule task, alternative choices are reinforced at different average intervals independent of the choice frequencies, and the choice behavior follows the so-called matching law. The two policies appear robustly in subjects' choice of behavior, but the underlying neural mechanisms remain unknown. Here, we show that these seemingly different policies can appear from a common computational algorithm known as actor-critic learning. We present experimentally testable variations of the VI schedule in which the matching behavior gives only a suboptimal solution to decision making and show that the actor-critic system exhibits the matching behavior in the steady state of the learning even when the matching behavior is suboptimal. However, it is found that the matching behavior can earn approximately the same reward as the optimal one in many practical situations.     

Interactive Visualization of News Distribution in Blog Space

This paper proposes a visualization method of news distribution in Blog space. Recently, Blog is becoming one of the important information resources on the Web, from which trend information can be obtained. On the other hand, online news site is another information resource, which reports latest events in the world. This paper focuses on the combination of both resources, and proposes a method for visualizing news distribution in Blog space, which indicates various access patterns to news articles in Blog space. The types of objects that are to be visualized as well as their relationships are defined, based on which interactive information visualization system is proposed. Experiments with test subjects are performed to investigate the viewpoints they employ for examining news distribution in Blog space. The results show that test subjects can examine news distribution in Blog space from various viewpoints, which affects their estimation of the impacts of news articles.

Effects of the addition of a liquid crystalline copolyester to polystyrenes on blending torque and mechanical properties of blends

Blending of polystyrenes (PS) with a thermotropic liquid crystalline polymer (LCP) was performed by using a continuous corotating twin screw extruder. The influence of LCP content on the blending process was studied by changing the barrel heater temperature and the screw speed. The torque of screw shafts, generated during the blending process, was influenced by LCP content and its influence was not simple. The torque generated during the blending process was not directly related to the apparent melt viscosity of blends. Further, the effects of the matrix viscosity on the morphology and mechanical properties of the PS/LCP blends were studied using three grades of PS as matrix resins. It was found that the size of the LCP dispersed phase decreased with increasing matrix viscosity. Consequently, the mechanical properties of the PS/LCP blend were improved. © 1993 John Wiley & Sons, Inc.     

Hydrogenation of 1,3-butadiene and of crotonaldehyde over highly dispersed Au catalysts

When Au is deposited as nano-particles on select metal oxides, it exhibits surprisingly high catalytic activity for many oxidation reactions. Therefore, there is also the possibility to improve the activities of Au catalysts for hydrogenation using the appropriate preparation methods like the gas-phase grafting method (GG) and the deposition precipitation method (DP). In this work, we investigated the hydrogenation of 1,3-butadiene and of crotonaldehyde over Au catalysts prepared by GG and DP and discussed the structure sensitivity of these reactions. From these experiments, it was found that the catalytic activities for the hydrogenation of 1,3-butadiene over Au catalysts was almost structure insensitive in terms of the size effect of Au particles and the influence of metal oxides supports and the crotonaldehyde hydrogenation over Au catalysts was slightly sensitive to the selection of the support in the view point of the product selectivity.     

Formation of the Ti4O7 phase through interaction between coated carbon and TiO2

Fine particles ofphotocatalytic anatase TiO₂ prepared through hydrolysis of titanium tetraisopropoxide were coated by carbon. A reduced phase, Ti₄O₇, was formed through interaction between TiO₂ and the coating carbon. EXAFS analysis on this Ti₄O₇ phase showed an intermediate Ti-Ti distance between those in anatase and rutile, which agreed with the structure composed of two-dimensional slabs of Ti-O octahedra separated by a shear plane. This carbon-coated Ti₄O₇ was confirmed to have photocatalytic activity, even though a little lower than anatase, examining the decomposition of methylene blue in water under LTV irradiation.     

Biotransporting Self‐Assembled Nanofactories Using Polymer Vesicles with Molecular Permeability for Enzyme Prodrug Cancer Therapy

As “biotransporting nanofactories”, in vivo therapeutic biocatalyst nanoreactors would enable encapsulated enzymes to transform inert prodrugs or neutralize toxic compounds at target disease sites. This would offer outstanding potential for next‐generation therapeutic platforms, such as enzyme prodrug therapy. Designing such advanced materials has, however, proven challenging. Here, it is shown that self‐assembled nanofactories formulate with polymeric vesicles with an intrinsically permeable membrane. The vesicles, CAPsomes, are composed of carbohydrate‐b‐poly(propylene glycol) and show molecular‐weight‐depended permeability. This property enables CAPsomes to act as biocatalyst nanoreactors, protecting encapsulated enzymes from degradation while acting on low‐molecular‐weight substrates. In tumor bearing mice, combined treatment with enzyme‐loaded CAPsomes and doxorubicin prodrug inhibit tumor growth in these mice without any observable toxicity. The results demonstrate, for the first time, in vivo therapeutic efficacy of CAPsomes as nanofactories for enzyme prodrug cancer therapy.