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A microneedle array is an attractive option for a minimally invasive means to break through the skin barrier for efficient transdermal drug delivery. Here, we report the applications of solid polymer-based ion-conductive porous microneedles (PMN) containing interconnected micropores for improving iontophoresis, which is a technique of enhancing transdermal molecular transport by a direct current through the skin. The PMN modified with a charged hydrogel brings three innovative advantages in iontophoresis at once: (1) lowering the transdermal resistance by low-invasive puncture of the highly resistive stratum corneum, (2) transporting of larger molecules through the interconnected micropores, and (3) generating electroosmotic flow (EOF). In particular, the PMN-generated EOF greatly enhances the transdermal molecular penetration or extraction, similarly to the flow induced by external pressure. The enhanced efficiencies of the EOF-assisted delivery of a model drug (dextran) and of the extraction of glucose are demonstrated using a pig skin sample. Furthermore, the powering of the PMN-based transdermal EOF system by a built-in enzymatic biobattery (fructose / O2 battery) is also demonstrated as a possible totally organic iontophoresis patch.

Applications of complex-valued neural networks (CVNNs) have expanded widely in recent years-in particular in radar and coherent imaging systems. In general, the most important merit of neural networks lies in their generalization ability. This paper compares the generalization characteristics of complex-valued and real-valued feedforward neural networks in terms of the coherence of the signals to be dealt with. We assume a task of function approximation such as interpolation of temporal signals. Simulation and real-world experiments demonstrate that CVNNs with amplitude-phase-type activation function show smaller generalization error than real-valued networks, such as bivariate and dual-univariate real-valued neural networks. Based on the results, we discuss how the generalization characteristics are influenced by the coherence of the signals depending on the degree of freedom in the learning and on the circularity in neural dynamics.

The lipid composition of plasma membranes and tonoplasts from etiolated mung bean hypocotyls was examined in detail. Phospholipids, sterols, and ceramide monohexoside(s) were the major lipid classes in both membranes. The content of phospholipids on a protein basis was higher in the tonoplast, but the content of total sterols was similar in both membranes. Accordingly, the sterol to phospholipid molar ratio in the plasma membrane was higher than that of the tonoplast. Phosphatidylethanolamine and phosphatidylcholine comprised the major phospholipids in both membranes. Phosphatidylinositol, phosphatidylserine, and phosphatidylglycerol were identified as minor phospholipid components. The content of phosphatidylinositol and phosphatidylglycerol was relatively high in the tonoplast, comprising 11 and 5% of the total phospholipids, respectively. Although special care was taken against the degradative action of phospholipase D and phosphatidic acid phosphatase during the isolation of these membranes, by adding EDTA, EGTA, KF, choline, and ethanolamine to the homogenizing medium, significant amounts of phosphatidic acid, about 15% of the total phospholipids, were detected in the plasma membrane. On the other hand, the content of phosphatidic acid in tonoplasts and other membrane fractions was very low. This fact may indicate that high levels of phosphatidic acid occur naturally in plasma membranes. Phosphatidylglycerol in both membranes and phosphatidylinositol in the tonoplast contained high levels of palmitic acid, which comprised more than 50% of the total fatty acids. Significant differences were observed in the sterol compositions of plasma membranes and tonoplasts. More than 90% of the sterols in the plasma membrane were unesterified, while the tonoplast was enriched in glycosylated sterols, especially acylated sterylglycosides. Ceramide monohexoside was found to be specifically located in these membranes, in particular, in the tonoplast, in which it comprised nearly 17% of the total lipids. is quite limited regarding the lipid composition of plasma membranes and tonoplasts, which also possess very important physiological functions including in the former, transport (22), cell wall biosynthesis (14), hormone action (24), phytochrome responses (18), and disease resistance (27), and in the latter, cellular compartmentation of lytic enzymes, acids, ions, and secondary products (I 1, 13). In addition, these membranes have been shown to play an important role in cold acclimation (29,31,33), freezing injury (26), and chilling stress (32).Recently we have established isolation methods for plasma membranes and tonoplasts from etiolated mung bean hypocotyls (34,35). In the present study, we have analyzed the lipid composition of both membranes and compared them. Plasma membranes are characterized by their high content of phosphatidic acid and tonoplasts by their high content of ceramide monohexoside. MATERIALS AND METHODSPlant Materials. Seeds of mung bean (Vigna radiata [L] Wilczek) were imbibed and germinate...

There is mounting evidence to indicate that membranes, primarily the plasma membrane, is intimately involved in cold acclimation and freezing injury (11,18,19,(24)(25)(26). Thus, it follows that plant plasma membranes must undergo certain chemical and biophysical changes during cold acclimation in order to withstand freezing stresses.There are several reports on changes in cellular membranes during cold acclimation (6,7,27). However, these are based on analytical data obtained from crude membrane fractions or total membrane extracts. Therefore, it is uncertain whether the reported changes are related to the changes in the plasma membranes per se during cold acclimation. Based on these facts, it is important to know what changes in the plasma membranes are responsible for the development offreezing tolerance during cold acclimation. A major problem encountered has been the difficulty ofisolating the plasma membrane in a high degree ofpurity needed for detailed studies. Recently, we have succeeded in preparing plasma membranes from light-grown winter rye seedlings with a high degree of purity using an aqueous two-polymer phase partition system (29).In the present study, Evaluation of Freezing Resistance. Freezing tolerance of the crown was evaluated by the ion-leakage test. One g fresh weight of tissues were cut into 5-mm-long pieces and were frozen in test tubes at -3°C for 2 h with small pieces of ice. Thereafter, the tissues were cooled in steps of 5°C at 2-h intervals and held at the desired temperatures for 2 h. After thawing at OC, the tissues were immersed in 5 ml of distilled H20 and incubated at room temperature for more than 5 h by gently shaking before measuring the conductivity. The tissues frozen directly in the liquid nitrogen and unfrozen were taken as 100% and 0% in the relative conductivity, respectively.Isolation of Plasma Membranes. Crown tissues were homogenized with a Polytron PT 20 at the medium speed for 90 s in a medium consisting of 0.5 M sorbitol, 50 mm MOPS2-KOH (pH 7.6), 10 mm EGTA neutralized with KOH, 2.5 mm potassium metabisulfite, 4 mM SHAM, 1 mm PMSF, 5% (w/v) soluble PVP (mol wt 24,500), and 1% (w/v) defatted BSA. The homogenate was passed through two layers of gauze and then two layers of Miracloth, and then centrifuged at 14,000g for 15 min and 156,000g for 20 min. The 156,000g pellet (14,000-156,000g fraction) was used for plasma membrane isolation using the aqueous two-polymer phase partition technique as reported previously (29). The purity of the isolated plasma membrane was determined by phosphotungstate-chromate staining and by specific aggregation in the presence ofZnCl2 or at pH 4.5 as reported previously (29). The isolated plasma membranes were suspended in 0.5 M sorbitol-3 mm Tris-maleate at pH 7.3 and kept at -70°C until use.Lipid Extraction. Total lipids were extracted from membrane samples according to the method of Bligh and Dyer (1) with the 2 Abbreviations: MOPS, 34N-morpholino)propanesulfonic acid;