Preparation of hafnium oxide thin films by sol–gel method

Hafnium oxide (HfO₂) films were grown on SiO₂/Si substrates by a sol–gel method, and their crystalline structure, microstructure and electrical properties were investigated. X-ray diffraction analysis indicated that the monoclinic HfO₂ films could be obtained by annealing at 500 °C. A transmission electron microscopy (TEM) image showed that the films were grown as a spherulite grain structure with a mean grain size of approximately 15 nm. The dielectric constant of the HfO₂ films of 300 nm was approximately 21.6, and the current–voltage measurements showed that the leakage current density of the HfO₂ films was approximately 1.14?×?10^?5 A/cm² at an applied electric field of 100 kV/cm. The sol–gel method-fabricated HfO₂ films are concluded to be feasible for MEMS applications, such as capacitive-type MEMS switches.     

Experimental Studies to Realize Josephson Junctions and Qubits in Cuprate and Fe-based Superconductors

Cuprate superconductors are very promising in terms of Josephson junction device because of the large energy scale of high-T _c superconductivity. In particular, fabrication of qubits attracts lots of attention because of its primary importance for future computer technology. We will present some of our recent activities pointing to this purpose. (1) We succeeded in fabricating Josephson junction of cuprate without making any extra oxide barrier layer, rather putting Fe islands on the small strip of cuprate superconductors. This is very promising, since the fabrication of good Josephson junction was unsuccessful so far. Together with the introduction of the data, we discuss the possible mechanism of the weak-link fabrication in this structure. (2) We investigated the switching events in the I–V characteristics of the intrinsic Josephson junctions of Bi-cuprate superconductor, where macroscopic quantum tunneling (MQT) observation is well established recently. In addition to confirm the MQT for the first switching at 1 K in the multiple-branched current–voltage characteristics, we found that the temperature independence of the switching distribution for the second switching up to higher temperatures (10 K) is not due to the trivial Joule heating. We discuss the mechanism of the phenomena, including the possibility of MQT. (3) New Fe-based superconductors are also promising in terms of the application of superconductivity, since the anisotropy looks rather weak, in contrast to cuprates. We will introduce our trial to fabricate epitaxial thin films as the initial step to fabricate Josephson junction of this material.     

A case of interstitial pneumonia in polymyositis difficult to distinguish from gold pneumonitis

Rheumatoid arthritis was diagnosed in a 48-year-old woman. She received a gold compound, and 4 weeks after the start of that therapy, interstitial pneumonia appeared. Findings from a muscle biopsy, and high serum CPK and LDH levels indicated that she suffered from polymyositis rather than rheumatoid arthritis. The result of a drug lymphocyte stimulation test (DLST) for the gold compound was more than 200%. Because the usefulness of the DLST for the gold compound in the diagnosis of gold pneumonitis is not thoroughly established, the DLST was also done in patients with rheumatoid arthritis who were receiving the gold compound without side effects, and in normal subjects. Many of the rheumatoid arthritis patients and some of the normal subjects had a positive response to the gold compound. Therefore a positive response on the DLST for the gold compound does not always support the diagnosis of gold pneumonitis.     

Expression of cytokines enhancing the osteoclast activity, and parathyroid hormone-related protein in prostatic cancers before and after endocrine therapy: an immunohistochemical study

Cytokines, interleukin (IL)-1alpha, IL-1beta, IL-3, IL-6, macrophage colony stimulating factor (M-CSF) and tumor necrosis factor-alpha (TNF-alpha) as well as parathyroid hormone-related protein (PTHrP) have been shown to enhance the osteoclast activity. To investigate mechanisms of the development of bone metastasis of prostatic cancers, expression of these cytokines and PTHrP was examined immunohistochemically in prostatic cancers of patients administered no prior therapy or endocrine therapy. All cytokines and PTHrP were stained in the cytoplasm of the epithelium of non-cancerous prostatic glands, and IL-3 and IL-6 were stained in the cytoplasm of smooth muscle cells besides epithelial cells of non-cancerous prostatic glands. Incidences of positivity of staining in prostate cancers of patients administered no prior therapy were 100% for IL-1alpha, IL-1beta, IL-6, M-CSF and TNF-alpha, 20% for IL-3, and 80% for PTHrP. Incidence of prostatic cancers stained positively for IL-1alpha and IL-1beta decreased significantly in patients administered endocrine therapy, but those for IL-3, IL-6, M-CSF, TNF-alpha and PTHrP did not change significantly. The present results suggest that prostatic cancers produce various cytokines, IL-1alpha, IL-1beta, IL-3, IL-6, M-CSF and TNF-alpha, as well as PTHrP, and that expression of these cytokines and PTHrP except IL-1alpha and IL-1beta is not under androgen control. Cytokines and PTHrP produced by prostatic cancers may play a role in the development of bone metastasis of prostatic cancers.     

A self-learning neural network chip with 125 neurons and 10 Kself-organization synapses

A learning neural network LSI chip is described. The chip integrates 125 neuron units and 10K synapse units with the 1.0 μm double-poly-Si, double-metal CMOS technology. Most of this integration has been realized by using a mixed design architecture of digital and analog circuits. The fully feedback connection network LSI can memorize at least 15 patterns with 50 μs learning time for each pattern. Under the condition that each test vector keeps a Hamming distance of 6 from memorized pattern, a correct association rate of 98% is obtained. The relaxation time is 1 to 2 μs. This chip consumes less than 7.5 W     

An evolutionary approach to associative memory in recurrent neural networks

In this paper, we investigate the associative memory in recurrent neural networks, based on the model of evolving neural networks proposed by Nolfi, Miglino and Parisi.Experimentally developed network has highly asymmetric synaptic weights and dilute connections, quite different from those of the Hopfield model.Some results on the effect of learning efficiency on the evolution are also presented.