Electrochemical detection and control of interactions between DNA and electroactive intercalator using a DNA-alginate complex film modified electrode

The surface of a glassy carbon electrode was modified with a DNA-alginate complex film in which water-soluble DNA was encapsulated into a calcium-alginate gel. The resulting modified electrode (DAFE) was used to detect ethidium bromide (EtBr), after its accumulation on the electrode. The intercalative behavior of EtBr for dsDNA in the film was investigated by measuring the electrode response based on the intercalation of EtBr separated from nonspecific interactions (electrostatic interaction). The accumulation of EtBr in the dsDAF was enhanced by applying a negative potential below -200 mV at the dsDAFE. When a positive potential above +700 mV was applied to the dsDAFE for a constant time with stirring in a Tris buffer solution, the amount accumulated decreased. These results indicate that it is possible to electrochemically control the accumulation and release of EtBr when a dsDAFE is used. In addition, the accumulation and detection of EtBr in spiked river water samples and daunomycin, an antitumor agent, is described.     

Reservoir characteristics and development plan of the Oguni geothermal field, Kyushu, Japan

Geothermal power development at the Oguni field, central Kyushu, is planned to begin in the year 2001 with a double flash system generating 20 MW_e. The Oguni reservoir has been delineated by systematic geothermal surveys, well tests and reservoir engineering studies. The fractured reservoir is horizontally layered and divided into northern and southern portions. Both of them have NaCl dominant fluids ranging from 200 to 240°C. The northern reservoir covers a large area including the Takenoyu Fault Zone and has a relatively high permeability (kh≈80–230 darcy-m). By contrast, the southern reservoir covers a relatively small area and has limited transmissivity. The southern reservoir has a higher pressure (1 MPa) than the northern reservoir, indicating little connectivity between them. Based on numerical calculations, as well as the surface topography and environmental aspects, the production and reinjection zones have been separated, and a large part of the necessary fluid will be produced from the northern reservoir along the Takenoyu Fault and a small part will be taken from the southern reservoir. The separated water will be reinjected into the northernmost part of the northern reservoir, in order to prevent a cold sweep problem for production.     

Daily oscillation of gene expression associated with nacreous layer formation

Three major organic matrix components, nacrein, MSI60 and N16 have been reported from the nacreous layer of Japanese pearl oyster, Pinctada fucata. Though several in vitro experiments have been carried out to elucidate the functions of these molecules details have not yet been clarified. In this report, we tempt to clarify the gene expression levels encoding the above three proteins between samples of 1) summer and winter seasons and 2) ocean and aquarium environments by using real-time polymerase chain reaction (PCR). It was confirmed that the biomineralization process of P. fucata is mainly influenced by the circatidal rhythm of the ocean environment. The gene expressions coding for N16 and MSI60 increased at the time of high tide, while that of nacrein increased at the time of low tide. The similar tendency observed in N16 and MSI60 showed the possibility that both components are secreted simultaneously, supporting a hypothesis that N16 forms cross-linkage with MSI60 to form the membrane. The expressions of MSI60, N16 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were remarkable in winter season, while no variation was found in the expression level of the nacrein gene in summer and winter season. The study is the first attempt regarding the seasonal and circadian rhythms observed on gene expressions incorporated into molluscan shell formation. The results will give a new insight into the relationship between molluscan physiology and the mechanism of shell formation.     

Control of cathodic potential for deposition of ZnO by constant-current electrochemical method

For the preparation of functional films and crystals, the electrochemical deposition method has advantages of large-area deposition at low temperature and high efficiency in terms of the raw materials used. However, crystallization through electrochemical processes is not currently well understood. To apply the electrochemical deposition method, it is necessary to better understand the crystallization and the growth mechanism. To investigate the mechanism, it is essential to ensure the reproducibility of the growth process. We focused on cathodic potential as a parameter that affects the reproducibility of the galvanostatic method. The repeatability of cathodic potentials during deposition was drastically improved by optimizing the mask pattern on the electrode and the pre-treatment conditions. As the result, the cathodic potential was able to be controlled by the current density. Furthermore, nucleation and grain growth of ZnO crystals by the galvanostatic electrochemical method are discussed in association with the change of cathodic potential. Changes in grain size at various cathodic currents are also discussed.     

Surgical treatment of syringomyelia associated with spinal dysraphism

Clinical and radiological features of syringomyelia in 15 patients with spinal dysraphism are reported. There were 8 patients with occult spinal dysraphism (lumbosacral lipoma) and 7 with spina bifida aperta (meningomyelocele). Syringomyelia with spinal dysraphism can be radiologically divided into two types according to the dysraphic state. The syrinx in the patients with occult spinal dysraphism occurred immediately rostral to the lipoma and was localized to the lower thoracic to lumbar levels, while in the meningomyelocele patients the syrinx extended from the cervical to the thoracic level. Large syrinx formation was recognized in 1 of the 7 occult spinal dysraphism cases and 3 of the 8 meningomyelocele cases. For syringomyelia with occult spinal dysraphism, 4 patients underwent syringo-subarachnoid shunting (S-S shunt, 2 cases) or syringostomy (2 cases) during an untethering operation. In the case of meningomyelocele, S-S shunts were placed in 2 patients. Collapse of the syrinx was achieved in all 6 patients who underwent S-S shunting or syringostomy. Decreased size of the syrinx was also noted in 3 occult spinal dysraphism patients who underwent untethering operations alone. In conclusion, a large syrinx in the case of spinal dysraphism should be surgically treated. S-S shunting is effective in both types of syringomyelia. Foramen magnum decompression may be an alternative method of surgical treatment for syringomyelia in patients with meningomyelocele.     

Influence of antiferromagnetic ordering on ferroelectric polarization switching of YMnO3 epitaxial thin films

In this study, the switching behavior of ferroelectric polarization of (0001) YMnO(3) epitaxial films at around Néel temperature was investigated. From the experimental results of the frequency and temperature dependences of coercive electric filed (E(c)) obtained from polarization-electric field (P-E) hysteresis loop, the crosscorrelation phenomena between magnetics and ferroelectrics are discussed in detail. The P-E hysteresis loops of the films were measured in the frequency range from 1 Hz to 10 kHz, and the temperature was varied from 10 to 150 K. Frequency dependence of Ec accorded with Ishibashi-Orihara's theory at the measured temperature range. However, temperature dependence of E(c) disagreed with Devonshire's theory below 120 K, which is close to the Néeel temperature of the YMnO(3) epitaxial film. disagreed with Devonshire's theory below 120 K, which is close to the Neel temperature of the YMnO(3) epitaxial film.     

Mechanical Property Evolution during Autoclaving Process of Aerated Concrete Using Slag: II, Fracture Toughness and Microstructure

The mechanical properties were investigated for autociaved aerated concrete (AAC) block samples, prepared using blast furnace slag at 180°C under saturated steam pressures for various times from 1 to 128 h. The mechanical properties of AAC made using slag are comparable to those made without slag. With increased autoclaving time, the compressive strength increases due to the binder effect of the 1.1-nm tobermorite. In contrast, the fracture energy G _F. and resistance to crack growth decrease with increase of autoclaving time. This dependency is caused by the formation of voids around unreacted slag particles.     

Daily oscillation of gene expression associated with nacreous layer formation

Three major organic matrix components, nacrein, MSI60 and N16 have been reported from the nacreous layer of Japanese pearl oyster, Pinctada fucata. Though several in vitro experiments have been carried out to elucidate the functions of these molecules details have not yet been clarified. In this report, we tempt to clarify the gene expression levels encoding the above three proteins between samples of 1) summer and winter seasons and 2) ocean and aquarium environments by using real-time polymerase chain reaction (PCR).It was confirmed that the biomineralization process of P. fucata is mainly influenced by the circatidal rhythm of the ocean environment. The gene expressions coding for N16 and MSI60 increased at the time of high tide, while that of nacrein increased at the time of low tide. The similar tendency observed in N16 and MSI60 showed the possibility that both components are secreted simultaneously, supporting a hypothesis that N16 forms cross-linkage with MSI60 to form the membrane. The expressions of MSI60, N16 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were remarkable in winter season, while no variation was found in the expression level of the nacrein gene in summer and winter season.The study is the first attempt regarding the seasonal and circadian rhythms observed on gene expressions incorporated into molluscan shell formation. The results will give a new insight into the relationship between molluscan physiology and the mechanism of shell formation.     

An adaptive noise reduction filter for discrete signal by use of sandglass‐type neural network

An adaptive noise reduction filter composed of a sandglass‐type neural network (SNN) noise reduction filter (RF) is proposed in this paper. SNN was originally devised to work effectively for information compression. It is a hierarchial network and is symmetrically structured. SNN consists of the same number of units in the input and output layers and a smaller number of units in the hidden layer. It is known that SNN has signal processing performance which is equivalent to Karhunen–Loeve expansion after learning. We proved the theoretical suitability of SNN for an adaptive noise reduction filter for discrete signals. The SNNRF behaves optimally when the number of units in the hidden layer is equal to the rank of the covariance matrix of the signal components included in the input signal. Further we show by applying the recursive least squares method to learning of the SNNRF that the filter can process signals for on‐line adaptive noise reduction. This is an extremely desirable feature for practical application. In order to verify the validity of SNNRF, we performed computer experiments examining how the noise reduction ability of SNNRF is affected by altering the properties of the input pattern, learning algorithm, and SNN. The results confirm that the SNNRF acquired appropriate characteristics for noise reduction from the input signals, and markedly improved the SNR of the signals. © 1999 Scripta Technica, Electr Eng Jpn, 127(4): 39–51, 1999