Fabrication of nano-gap structures based on plastic deformation of strained Si springs by stiction effects

In this research, we propose a simple method to create nano-gaps with photolithography by a post-annealing process. The idea based on plastic deformation of strained Si springs by annealing is demonstrated. The resonator and the spring electrodes used to actuate and measure the resonant amplitude with a gap of a few microns were designed and fabricated. The force of water tension during evaporation was used to generate a strain in the springs. After drying, sticking effects were observed between the resonator and the electrodes with oxide layers. By post-annealing and removal of the oxide layers, the micro-gap was reduced to a nanometer gap by plastic deformation of highly doped Si.     

MRT letter: Expression of ATP sensor protein in Caenorhabditis elegans

Adenosine 5'-triphosphate (ATP) is the major energy currency and is involved in many biological processes. The ATP-monitoring system for cells in animals can be helpful to study the relationship between energy metabolism and biological processes. The fluorescent ATP biosensor ATeam (ATP indicator based on Epsilon subunit for Analytical Measurements), which has been reported to monitor ATP levels in cultured cells on the basis of fluorescence resonance energy transfer (FRET), was introduced into nematodes by microinjection and UV-irradiation method. To confirm whether ATeam functions as an ATP sensor in nematode cells, the authors measured FRET of ATeam in cells of transgenic nematode. The ATeam was expressed in target cells in nematode. In vulva cells, ATP levels in the cytosol were higher than those in mitochondria. ATeam also sensed ATP level change in cultured cells from the transgenic nematode. These experiments indicated that ATeam is available for detection of changes in ATP levels in nematode cells.     

A sensitive method for measuring organic carbon in sediment

In order to determine organic carbon in sediments, a sensitive method was devised by the combination of an ordinary wet combustion and TOC analyzer for aqueous samples. The carbon dioxide evolved by wet combustion was absorbed into 0.2 N NaOH solution and determined with a TOC analyzer. The accuracy and the determination limit of the method were determined. Carbon ranges from 0.4 to 48 mg were determined accurately without interference of chlorine and sulfur. This method was applied to the study of the composition of river sediment on the basis of extractability by various solvents.     

Sustainable hydrogen production system with sulfur–water–organic materials by hydrothermal reaction

Engineered process for hydrogen generation from hydrogen sulfide ions in aqueous solution using solar energy with photocatalysis has been established. In order to design a complete closed loop of hydrogen production system, reacted sulfide ions have to be reduced to photocatalysis-active hydrogen sulfide ion. We focused on hydrothermal reaction of sulfur for reducing the reacted sulfide ions. But the oxidized sulfur species are occurred inevitably by the reaction. Thus alternative reducers are required to sulfur hydrothermal reaction for a complete closed loop of hydrogen production system. We studied sulfur–water–organic materials interaction, and particularly on the effective utilization of waste elemental sulfur. In this study, hydrothermal experiments of sulfur, water urea, and/or alcohols were carried out under atmospheric constituent condition and hypoxic condition at 200 °C. Experimental results show that maintaining solution in weak alkaline condition is important and alcohol compounds had a great role for reduction of sulfur. Elemental sulfur was completely reduced to hydrogen sulfide by the hydrothermal reaction of sulfur with urea and propanol under hypoxic condition. Those results indicate that it is possible to create sustainable sulfur cycle for hydrogen production system using hydrothermal reaction with organic compounds.     

ESR spectroscopy for analysis of hippocampal elimination of a nitroxide radical during kainic acid-induced seizure in rats

To analyze the balance between free radical production and elimination during seizure, techniques were developed to monitor the sequential changes in the level of an exogenous free radical by ESR in the brains of freely moving rats given kainic acid (KA) to induce seizures (n = 6) and control rats given saline (n = 6). The hippocampus of each rat was perfused with a nitroxide radical solution for 120 min by in vivo microdialysis. Then an intraperitoneal injection of KA or the physiological saline was given to each rat, and the perfusate was changed to Ringer's solution. ESR analysis of sequential samples of dialysate taken after injection revealed an exponential decay in signal amplitude. The median half-life of the nitroxide radical was significantly longer in the KA-treated group than in the control group (P < 0.01). This finding demonstrates a decreased capacity of the hippocampus to eliminate the nitroxide radical from the extracellular space during seizure and may help clarify the mechanism of neuronal cell vulnerability to free radicals during insult or degeneration.     

Control elements of Dnmt1 gene are regulated in cell-cycle dependent manner

The Dnmt1 gene is constitutively expressed and is required for the maintenance of global methylation after DNA replication. We investigated here the effects of histone deacetylase (HDAC) inhibitor and DNA demetylation agent on promoter activity of mouse Dnmt1 gene in somatic cells. The promoter activity of Dnmt1 gene was increased approximately 2-fold in the treatment of cells by Tricostatin A (TSA) at 1 x 10(-8) M, as compared with that without treatment of TSA. By contrast, treatment with 5-azacytidne (5aza-C) did not affect the promoter activity of the Dnmt1 gene. This result indicates the Dnmt1 gene is possibly regulated by histone acetylation. We also examined the expression levels of Dnmt1 gene and of its control elements like Sp1, Sp3 and p300 by the chromatin immunoprecipitation and Western blot analysis. The expression of Dnmt1 gene is observed at early S phase. Sp1 is recruited mainly at the G1 phase and Sp3 is recruited at the early S phase. p300 is also obviously recruited at the second S phase. These data indicated that the regulators of Dnmt1 gene were controlled in cell-cycle dependent manner.     

Fas antigen expression of hepatocytes and its modification by immunosuppressants

Active cell death induced by ligation of the Fas antigen (Fas-Ag) with its antibody, Fas ligand (Fas-L), has been known to play a major role in cell killing via apoptosis by cytotoxic T lymphocytes (CTL). Thus, in liver transplantation, Fas-Ag expression of hepatocytes and its modification by immunosuppressive agents such as FK 506 or CsA can theoretically influence allograft survival. Mouse hepatocytes (BALB/c) were isolated and cultured with or without FK 506 or CsA, and Fas-Ag expression was determined by flow cytometry. Fas-Ag expression in the control was 17.2 +/- 2.5% after 24 hr of culture. When FK 506 or CsA was added, Fas-Ag expression with FK 506 at a concentration of 0.01-0.1 microg/ml was significantly lower than that with CsA (P < 0.05). When the cells were incubated with apoptosis-inducing anti-Fas-Ag monoclonal antibody, agarose gel electrophoresis of the control cells yielded a typical pattern of DNA fragmentations. The cells with FK 506 at 0.01 microg/ml yielded the least DNA fragmentation. These findings suggested that in the in vivo setting, the hepatocytes of the allograft would have a lower chance of being attacked by CTL in the host treated with FK 506.     

Collaboration is key internationally

Today, many universities report record numbers of students enrolling in power and energy engineering courses. The power and energy industry shows strong interest in hiring qualified graduates, and the latter see exciting employment opportunities. Issues of power, energy, and environmental impact increasingly are at the center of interest at local conferences, are on the agenda of world summits, and are subject to active debate. The quest for effective and environmentally friendly solutions to energy problems stands at the forefront of a new era. The challenges involved call for an active interaction of university and industry in research and education, and this is the main subject of this article. The article is intended to give the reader an insight into existing forms of collaboration, to evaluate the benefits, and to discuss the trends of active interaction of university and industry in the diverse cultures of different countries. Typical mechanisms of collaboration are reviewed and the benefits resulting from collaboration for both industry and university are evaluated and elaborated upon. Based on these considerations, desirable features of university-industry collaboration today and in the future are discussed.     

Active coordinated operation of a distribution network system for many connections of distributed generators

Recently, the total number of distributed generators (DGs) such as photovoltaic generation system and wind turbine generation system connected to an actual distribution network has increased drastically. The distribution network connected to many distributed generators must be operated keeping reliability of power supply, power quality, and loss minimization. In order to accomplish active distribution network operation to take advantage of many connections of DGs, a new coordinated operation of distribution system with many connections of DGs is necessary. In this paper, the authors propose a coordinated operation of distribution network system connected to many DGs by using newly proposed sectionalizing switch control, sending voltage control, and computation of available DG connection capability. In order to check the validity of the proposed coordinated operation of distribution system, numerical simulations using the proposed coordinated distribution system operation are carried out in a practical distribution network model. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(3): 46–57, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20655     

Multilayered transformer utilizing Mn‐Zn ferrite and its application to a forward‐type DC–DC converter

This paper describes the electrical characteristics of a multilayered transformer composed of a Mn‐Zn ferrite core, and primary and secondary conductors positioned alternately not only in the vertical direction but also in the horizontal direction. In order to elucidate the operating characteristics of the two types of transformers, one was given the conventional planar winding structure and the other the new winding structure described above, and a two‐dimensional finite element method that took account of the two conditions and a constant input voltage and load current was introduced. The coupling coefficient of the conventional multilayered transformer deteriorated with increasing load current. But the coupling coefficient of the proposed multilayered transformer was independent of the load current. A forward‐type DC–DC converter using the new multilayered transformer had higher efficiency than a converter using the conventional multilayered transformer. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 1–8, 2001