74 results on '"Hidemi Takasu"'
Search Results
2. A great saphenous vein aneurysm in a child: A rare disorder misdiagnosed as an inguinal hernia
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Wataru Sumida, Yoshio Watanabe, Naoki Hashizume, Naoko Komatsuzaki, Hidemi Takasu, Minoru Yagi, and Kazuo Oshima
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medicine.medical_specialty ,lcsh:Surgery ,Vascular malformation ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,medicine ,Thrombus ,Vein ,Groin ,business.industry ,Great saphenous vein ,Inguinal hernia ,lcsh:RJ1-570 ,lcsh:Pediatrics ,lcsh:RD1-811 ,medicine.disease ,Great saphenous vein aneurism ,Surgery ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Pediatrics, Perinatology and Child Health ,cardiovascular system ,Radiology ,business ,Lower limbs venous ultrasonography - Abstract
We report a case of primary great saphenous vein aneurysm (GSVA) in a 3 years old girl. A growing mass at the right groin region had been detected in the upright position during the last two years, which was misdiagnosed as inguinal hernia at the referral hospital. The Doppler ultrasound scanning (DUS) showed the findings of GSVA such as the 2 cm soft cystic mass from the great saphenous vein accompanying with the turbulence flow, whereas with no vein thrombosis. GSVA was resected after the ligation of the distal part of the great saphena vein. There was no sign of the recurrence in 1-year follow up at the outpatient examination. Primary GSVAs are rare lesion and were often misdiagnosed and confused as soft tissue tumor or inguinal hernia (J.S. de Miranda et al., 2015; G.A. Ranero-Juarez et al., 2005). As the diagnostic imaging for GSVAs, DUS is therefore effective in detecting the aneurysms and the presence of a thrombus.
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- 2016
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3. Early jejunostomy creation in cases of isolated hypoganglionosis: verification of our own experience based on a national survey
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Keiichi Uchida, Wataru Sumida, Hidemi Takasu, Yutaka Kanamori, Yoshio Watanabe, Kazuo Oshima, and Tomoaki Taguchi
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Male ,medicine.medical_specialty ,Time Factors ,medicine.medical_treatment ,Jejunostomy ,Kaplan-Meier Estimate ,Stoma ,Ileostomy ,Japan ,Humans ,Medicine ,Hirschsprung Disease ,Survival rate ,Pain, Postoperative ,business.industry ,Age Factors ,Infant, Newborn ,Infant ,General Medicine ,Bowel resection ,Hypoganglionosis ,medicine.disease ,Surgery ,Intestines ,Radiography ,Survival Rate ,Bowel obstruction ,Child, Preschool ,Female ,business ,Organ Sparing Treatments ,Follow-Up Studies ,Rare disease - Abstract
Isolated hypoganglionosis (IH) is a rare disease, with few well-established therapeutic strategies. This study aims to verify our preliminary therapeutic strategies developed to date in a comparison with data obtained from a nationwide survey of congenital-type IH. Of the 90 registered IH cases assessed in a survey of Japanese pediatric surgical departments, 40 patients who had initially undergone jejunostomy (JE) and 41 treated with ileostomy (IL) were analyzed. Thirteen patients with JE sites located less than 50 cm from the ligament of Treitz were defined as having undergone upper jejunostomy (UJE). Postsurgical plain abdominal X-ray findings and survival rates, estimated using the Kaplan–Meier method, were used to evaluate improvements following stoma creation. Improvements in bowel obstruction were observed in significantly more UJE patients (9/13) than non-UJE patients [20/63 (22 JE and 41 IL cases); p = 0.01]. Furthermore, the JE patients demonstrated a significantly higher survival rate than the IL patients (p = 0.01). Following the completion of the 10-year follow-up period, three JE patients died after undergoing massive bowel resection. To manage IH successfully, patients should undergo JE less than 50 cm from the ligament of Treitz during the neonatal period. Properly managing the distal intestines is important for achieving long-term survival.
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- 2015
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4. Cinematic magnetic resonance enterography for non-organic abdominal pain in infants and children
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Wataru Sumida, Yoshio Watanabe, Kazuo Ohshima, and Hidemi Takasu
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Abdominal pain ,medicine.medical_specialty ,Gastrointestinal tract ,medicine.diagnostic_test ,business.industry ,Magnetic resonance imaging ,Magnetic resonance enterography ,Rome iii ,Positive predicative value ,Pediatrics, Perinatology and Child Health ,medicine ,Small bowel disease ,Radiology ,medicine.symptom ,business ,Fasting state - Abstract
Background Recurrent non-organic abdominal pain is the most commonly diagnosed medical problem in children. However, excluding small bowel disease remains a challenge. We evaluated our exclusion criteria for organic small intestinal diseases in pediatric patients with recurrent non-organic abdominal pain using cinematic magnetic resonance (cine-MR) enterography. Methods The non-intestinal organic (non-IO) group as classified by the Rome III criteria system and the intestinal organic (IO) group consisted of 81 and 19 patients, with 35 and 12 male and 46 and 7 female patients with an age range of 5–18 and 4–15 years (average 10.5 and 10.5 years), respectively. Cine-MR enterography was performed by dynamically balanced first-field-echo imaging with thick-slice water-selective excitation without breath holding. In our original small intestinal motility test, cine-MR enterography was taken at three different times (fasting state [P1], immediately after [P2] and 30 min after [P3] drinking liquid material), with images taken sequentially for 5 min at each time-point to evaluate the motion of water in the gastrointestinal tract. Positive findings for organic intestinal problems were concluded when persistent visible intestinal loops appeared in both the P1 and P2 phases. Results Cine-MR enterography showed 6/81 (7.4%) and 18/19 (94.7%) (P < 0.01) positive cases of organic intestinal problems in the non-IO and IO groups, respectively. Positive and negative predictive values of this examination were 78.3% and 97.4%, respectively. Conclusions The unique capabilities of cine-MR enterography technology in this clinical setting render it an important additional diagnostic tool when specific disease management issues must be addressed.
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- 2014
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5. Acute gastric volvulus with total gastric necrosis and ischemia of the spleen and kidney
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Yuki Sengoku, Kazuki Yokota, Hidemi Takasu, and Yasuyuki Ono
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medicine.medical_specialty ,Necrosis ,Gastric Dilatation ,Decompression ,lcsh:Surgery ,Ischemia ,Spleen ,Gastric necrosis ,Gastroenterology ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Kidney ,business.industry ,digestive, oral, and skin physiology ,lcsh:RJ1-570 ,lcsh:Pediatrics ,lcsh:RD1-811 ,medicine.disease ,digestive system diseases ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Pediatrics, Perinatology and Child Health ,030211 gastroenterology & hepatology ,Surgery ,Acute gastric volvulus ,medicine.symptom ,business - Abstract
We report a case of a 6-year-old female with acute gastric volvulus with total gastric necrosis and ischemia of the surrounding organs. Congestion necrosis occurs because of strangulation. It is considered that this case was caused by elevated intragastric pressure with marked stomach dilation. Thus, rapid decompression was essential. Keywords: Acute gastric volvulus, Total gastric necrosis, Ischemia of surrounding organs, Acute gastric dilatation
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- 2019
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6. Wide variation in anal sphincter muscles in cases of high- and intermediate-type male anorectal malformation
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Wataru Sumida, Hidemi Takasu, Kensaku Mori, and Yoshio Watanabe
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Male ,medicine.diagnostic_test ,business.industry ,Anal Canal ,Muscle, Smooth ,Computed tomography ,General Medicine ,Anatomy ,Anus ,Anorectal Malformations ,Intermediate type ,Helical ct ,Anus, Imperforate ,medicine.anatomical_structure ,Male patient ,Pediatrics, Perinatology and Child Health ,Humans ,Medicine ,Sphincter ,Surgery ,business ,Anal sphincter ,Sphincter muscle - Abstract
The distribution of sphincter muscle complex in anorectal malformation (ARM) needs to be investigated on a case-by-case basis. This study was undertaken to demonstrate the differences in the anal sphincter muscles between patients with the same type of ARM. Computed tomography (CT) data from cases of high- and intermediate-type male patients with ARM were reviewed using three-dimensional (3D) image analysis. Twenty-seven male patients with ARM (18 high and 9 intermediate) before anorectoplasty were assessed using multidetector-row helical CT (MRH-CT). A 3D reconstruction was made using volume rendering method. The multi-dimensional sections of the 3D reconstructed images of the pelvic muscles were then analyzed and compared with schematic drawings from the literature. The sphincters in the high and intermediate types of ARM could be divided into five groups. In 13 out of 18 cases in the high type and 7 out of 9 cases in the intermediate type, images of the sphincter muscles appeared different from schematic drawings appearing in the literature. In both high and intermediate types of ARM, more than 2/3 of cases demonstrated unexpectedly displaced and deformed hypoplastic sphincters. Therefore, we recommend that variations in anal sphincter should be investigated on an individual basis prior to surgery.
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- 2013
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7. 'More than Moore' expands the semiconductor world
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Hidemi Takasu
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Semiconductor industry ,Engineering ,Commerce ,Semiconductor ,Promotion (rank) ,business.industry ,media_common.quotation_subject ,Electrical engineering ,Electronics ,Semiconductor device ,business ,Dram ,media_common - Abstract
Up to now, the semiconductor industry has been developed under the promotion of the fine processing technology. The power relationships of the semiconductor industry have been changed drastically at the each advent of products used advanced fine process. In the past, this phenomenon is observed on the DRAM business frequently. Therefore, it is often said that semiconductor industry has the gambling property of high risk-high return on the business.
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- 2016
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8. Strategies for catheter-related blood stream infection based on medical course in children receiving parenteral nutrition
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Wataru Sumida, Hidemi Takasu, and Yoshio Watanabe
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Catheterization, Central Venous ,medicine.medical_specialty ,medicine.medical_treatment ,Bacteremia ,Catheters, Indwelling ,Risk Factors ,Pediatric surgery ,Humans ,Medicine ,In patient ,Child ,Intensive care medicine ,Bacteria ,business.industry ,General Medicine ,Prognosis ,equipment and supplies ,medicine.disease ,Catheter-Related Infections ,Anti-Bacterial Agents ,Catheter ,Parenteral nutrition ,Practice Guidelines as Topic ,Pediatrics, Perinatology and Child Health ,Parenteral Nutrition, Total ,Surgery ,business ,Blood stream ,Central venous catheter - Abstract
The central venous catheter (CVC) is a useful device for patients requiring parenteral nutrition (PN). However, the risk for catheter-related blood stream infection (CRBSI) is always present. We analyzed the medical course pattern and considered the strategies against febrile events in patients with CVC.Nine patients receiving PN in our institute from January 2009 to December 2010 were reviewed. Statistical analysis was performed with the Mann-Whitney U test. A p value of0.05 was considered statistically significant.Eighty-four febrile events were observed. Fifty-six specimens had a positive blood culture, and 52 (93%) specimens were found to be positive in 48 h. The fever dissolved within 48 h in 76 (90%) events after our scheduled treatment. Between the positive and negative blood culture groups, no statistical difference was observed in the count of white blood cell (p = 0.15), the proportion of neutrophils (p = 0.11) and C-reactive protein (p = 0.64). None of the CVCs were removed because of failure to control infection.We recommend the treatment for CRBSI be initiated when patients with CVC develop a high-grade fever, even before exact identification of the cause of infection. The treatment can be corrected after the re-evaluation at 48 h.
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- 2011
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9. Umbilicoplasty with 3 triangular skin flaps and excised diamond-shaped skin flap
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Hidemi Takasu and Yoshio Watanabe
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Male ,medicine.medical_specialty ,Erythema ,Umbilicus (mollusc) ,Skin flap ,Free Tissue Flaps ,Surgical Flaps ,medicine ,Humans ,Minimally Invasive Surgical Procedures ,Hernia ,Prospective Studies ,Umbilicus ,business.industry ,Umbilicoplasty ,Suture Techniques ,Infant ,Granulation tissue ,General Medicine ,Anatomy ,Fascia ,Plastic Surgery Procedures ,medicine.disease ,Surgery ,Umbilical hernia ,body regions ,Treatment Outcome ,medicine.anatomical_structure ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,Female ,medicine.symptom ,business ,Hernia, Umbilical - Abstract
Purpose In cases of large umbilical hernias, standard surgical techniques have proven inadequate for diminishing the diameter of the umbilicus. We have modified the 3- and 4-triangular-skin-flap techniques to diminish the diameter of the umbilicus and achieve a cosmetically acceptable umbilicus. Materials and Methods Umbilicoplasty was performed in 149 children (median age, 2.5 years; range, 3 months-10 years) between 2003 and 2008. We created 4 skin flaps 1.5 cm in length on the umbilicus and excised the cranial diamond-shaped skin flap. After closure of the fascial defect, the diameter of the umbilicus was diminished by suturing the opened cranial part of the diamond-shaped skin flap vertically. The tips of the 3 remaining flaps were then anchored to the closed fascia. Results Postoperatively, granulation tissue occurred in 18 cases (12%), transient erythema of a flap in 15 cases (10%), and bulging of a skin flap in 15 cases (10%). These complications were reduced by suturing adjoining skin flaps. No recurrent hernias were encountered. The postoperative umbilical appearance was satisfactory in all cases. Conclusion This surgical technique is effective for diminishing the diameter of the umbilicus and creating a cosmetically acceptable shaped umbilicus, even for large umbilical hernias.
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- 2010
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10. Unexpectedly deformed anal sphincter in low-type anorectal malformation
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Kensaku Mori, Yoshio Watanabe, and Hidemi Takasu
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Male ,Helical computed tomography ,Anorectal anomalies ,Fistula ,Anal Canal ,Surgical methods ,Imaging, Three-Dimensional ,Image Processing, Computer-Assisted ,medicine ,Humans ,Rectal Fistula ,Muscle, Skeletal ,Digestive System Surgical Procedures ,business.industry ,Rectum ,Infant ,General Medicine ,Anatomy ,medicine.disease ,medicine.anatomical_structure ,Pediatrics, Perinatology and Child Health ,Personal computer ,Sphincter ,Female ,Surgery ,Tomography ,Anal sphincter ,business ,Tomography, Spiral Computed ,Software - Abstract
Purpose The sphincter muscles in anorectal anomalies, which do not appear in the surgical field, cannot be described adequately. Details of the anal sphincter in low-type anorectal malformations were investigated using 3-dimensional (3D) image analysis. Patients and Methods Thirty patients (10 males and 20 females) with low-type anorectal malformation were investigated with multidetector-row helical computed tomography. An image of the anorectal part was obtained with a slice thickness of 1 mm and a reconstruction pitch of 0.5 mm. A 3D reconstruction on a personal computer was made with a volume rendering method assisted by our own software (NewVES). Results Very thin vertical fibers (VFs) were observed behind the fistula in almost half of the low-type cases. They did not wrap the distal end of the fistula. The 3D images of these sphincters were different in each case. Discussion The fistula was dislocated forward from the deformed hypoplastic sphincter. We suggest that surgical mobilization of the anorectum into the center of the hypoplastic sphincter would be difficult using the cut back or Potts methods. Conclusion The choice of surgical method should take into consideration the displaced and deformed hypoplastic anal sphincter.
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- 2009
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11. Development of (Pb,La)(Zr,Ti)O3Electro-Optic Thin Film for High-Speed Spatial Light Modulator
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Yoshikazu Fujimori, Hidemi Takasu, Takashi Nakamura, Masato Moriwake, Suzuki Tatsuya, and Tsuyoshi Fujii
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Materials science ,Spatial light modulator ,Physics and Astronomy (miscellaneous) ,Electro-optic effect ,business.industry ,General Engineering ,General Physics and Astronomy ,Chip ,Optical switch ,Switching time ,Optics ,Thin film ,business ,Refractive index ,Voltage - Abstract
A high-speed electro-optic spatial light modulator (EOSLM) was successfully fabricated with (Pb,La)(Zr,Ti)O3 (PLZT) electro-optic thin film. This EOSLM has a longitudinal structure, so a large electro-optic effect is necessary for low driving voltage (
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- 2006
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12. Photoluminescence recombination centers in ZnO
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I. Niikura, Koji Matsubara, Kakuya Iwata, Hajime Shibata, S. Niki, Shogo Ishizuka, Hitoshi Tampo, Kang Min Kim, Akimasa Yamada, Keiichiro Sakurai, Kouji Maeda, Ken Nakahara, Hidemi Takasu, Kentaro Tamura, Masamichi Sakai, and Paul Fons
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Crystal ,Photoluminescence ,Chemistry ,Lattice defects ,Analytical chemistry ,Rapid thermal annealing ,Atomic physics ,Impurity doping ,Condensed Matter Physics ,Spectral line ,Recombination - Abstract
We have studied the effects of (i) impurity doping, (ii) rapid thermal annealing, and (iii) crystal polarity control on photoluminescence spectra in the band-edge emission region of high quality ZnO. As a result, we have discussed the possible lattice defects responsible for some photoluminescence emission peaks, namely (i) peak I8 appears at 3.3596 eV, (ii) peak I9 appears at 3.3565 eV and (iii) peak G appears at 3.3327 eV. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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- 2006
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13. The effects of thermal treatments on the electrical properties of phosphorus doped ZnO layers grown by MBE
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S. Niki, Paul Fons, Hajime Shibata, Kakuya Iwata, Kentaro Tamura, Koji Matsubara, Hitoshi Tampo, Hidemi Takasu, and Akimasa Yamada
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Photoluminescence ,Reflection high-energy electron diffraction ,Chemistry ,Phosphorus ,Doping ,Ion plating ,Inorganic chemistry ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,Oxygen ,Inorganic Chemistry ,Materials Chemistry ,Thin film ,Molecular beam epitaxy - Abstract
Phosphorus-doped ZnO films were grown by radical source molecular beam epitaxy (RS-MBE). Zn 3 P 2 was used for the phosphorus source. ZnO:P layers were grown on an in situ annealed low temperature buffer layers, and the phosphorus concentration was changed by altering the temperature of the Zn 3 P 2 K-cell. The phosphorus concentration could be controlled from 1 x 10 18 to 2 x 10 20 cm -3 without phase separation. The importance of the ambient gas used during thermal treatments was demonstrated. All of the ZnO:P layers showed n-type conduction, however, the electron concentration of ZnO:P was found to decrease by as much as from 4.1 × 10 19 to 9.7 x 10 16 cm -3 when the samples underwent oxygen ambient rapid thermal annealing (RTA) treatment. Furthermore, a new photoluminescence peak at 3.357eV was observed after RTA treatment, which was not present in undoped ZnO layers before and after RTA treatment. These results indicate that the activation of acceptors in ZnO:P occurred in samples that underwent RTA treatment and that phosphorus is a good candidate as an acceptor dopant.
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- 2005
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14. Ferroelectric Non-Volatile Logic Devices
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Hidemi Takasu, Michitaka Kameyama, Takahiro Hanyu, Hiromitsu Kimura, Yoshikazu Fujimori, and Takashi Nakamura
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Scheme (programming language) ,Materials science ,Pass transistor logic ,business.industry ,Logic family ,Electrical engineering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Power (physics) ,law.invention ,Reduction (complexity) ,Capacitor ,Hardware_GENERAL ,Control and Systems Engineering ,law ,Power module ,Materials Chemistry ,Ceramics and Composites ,Electrical and Electronic Engineering ,business ,computer ,Hardware_LOGICDESIGN ,computer.programming_language ,Electronic circuit - Abstract
The reduction of the power consumption is becoming more essential for portable systems. A powering down scheme is very useful to reduce power comsumption of LSIs. The scheme needs to keep logic state, so several latch circuits have been reported. However, these methods require large additional circuit or special manufacturing process. A non-volatile latch with ferroelectric capacitors is simple and smart way [1], and its area penalty is very small. The non-volatile device needs no power supply for data keeping. Moreover, a dynamic reconfigurable logic can be possible by using the non-volatile latch as non-volatile switches.
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- 2004
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15. Complementary ferroelectric-capacitor logic for low-power logic-in-memory VLSI
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Hidemi Takasu, Yoshikazu Fujimori, Michitaka Kameyama, Hiromitsu Kimura, Takashi Nakamura, and Takahiro Hanyu
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Pass transistor logic ,Computer science ,Hardware_PERFORMANCEANDRELIABILITY ,Ferroelectric capacitor ,law.invention ,Hardware_GENERAL ,law ,Low-power electronics ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Electrical and Electronic Engineering ,Standby power ,Dynamic logic (digital electronics) ,Capacitive coupling ,Very-large-scale integration ,Hardware_MEMORYSTRUCTURES ,business.industry ,Electrical engineering ,Ferroelectricity ,Active devices ,Capacitor ,Logic synthesis ,CMOS ,Logic gate ,business ,Voltage - Abstract
A novel nonvolatile logic style, called complementary ferroelectric-capacitor (CFC) logic, is proposed for low-power logic-in-memory VLSI, in which storage elements are distributed over the logic-circuit plane. Standby currents in distributed storage elements can be cut off by using ferroelectric-based nonvolatile storage elements, and the standby power dissipation can be greatly reduced. Since the nonvolatile storage and the switching functions are merged into ferroelectric capacitors by the capacitive coupling effect, reduction of active device counts can be achieved. The use of complementary stored data in coupled ferroelectric capacitors makes it possible to perform a switching operation with small degradation of the nonvolatile charge at a low supply voltage. The restore operation can be performed by only applying the small bias across the ferroelectric capacitor, which reduces the dynamic power dissipation. Applying the proposed circuitry in a fully parallel 32-bit content-addressable memory results in about 2/3 dynamic power reduction and 1/7700 static power reduction with chip size of 1/3, compared to a CMOS implementation using 0.6-/spl mu/m ferroelectric/CMOS.
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- 2004
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16. Thermal processing induced structural changes in ZnO films grown on (11&2macr;0) sapphire substrates using molecular beam epitaxy
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Akimasa Yamada, Kakuya Iwata, Hidemi Takasu, S. Niki, Hitoshi Tampo, Koji Matsubara, Ken Nakahara, and Paul Fons
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Diffraction ,Reciprocal lattice ,Crystallography ,Materials science ,Annealing (metallurgy) ,Thermal ,Sapphire ,Nitrogen doping ,Analytical chemistry ,Buffer (optical fiber) ,Molecular beam epitaxy - Abstract
We have investigated the effect of in-situ annealing and nitrogen doping on 40 nm low-temperature buffer layers in radical-source molecular beam epitaxy (RS-MBE) as well as subsequently grown high-temperature ZnO layers grown on the buffers. All layers were grown on (11&2macr;0) sapphire substrates. High resolution x-ray reciprocal space maps in the vicinity of the ZnO (0002) reciprocal lattice point (RLP) showed a sharp reduction in diffuse scattering for the thermally annealed buffer layer implying a reduction in dislocation density. X-ray lateral coherence (LC) values obtained from asymmetric diffraction near the (10&1macr;4) RLP indicated that the LC of a undoped, high-temperature ZnO layer grown on an in-situ N-doped buffer was larger than those of high-temperature ZnO layers grown on either the in-situ annealed or untreated low-temperature buffers. The increased LC was found to be correlated with in-plane twist suggesting that dislocation bunching may be present at domain boundaries in the high-temperature ZnO grown on annealed N-doped buffer layers. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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- 2004
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17. An EXAFS and XANES study of MBE grown Cu-doped ZnO
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Hidemi Takasu, S. Niki, Ken Nakahara, Kakuya Iwata, Paul Fons, Akimasa Yamada, and Koiji Matsubara
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Nuclear and High Energy Physics ,Valence (chemistry) ,Materials science ,Extended X-ray absorption fine structure ,Dopant ,Doping ,Analytical chemistry ,Valency ,Epitaxy ,Instrumentation ,Molecular beam ,XANES - Abstract
The wide bandgap semiconductor, ZnO, is intrinsically n-type and one of the remaining hurdles to be overcome before it can be used for optoelectronic applications is achieving p-type doping. A potential candidate for a p-type dopant is Cu. Towards this end, X-ray near-edge absorption (XANES) has been used to determine changes in valency of Cu in molecular beam epitaxial grown ZnO as a function of growth parameters. Growth parameters varied include the Cu flux which was varied over roughly three orders of magnitude TCu=800–1000 °C and two substrate temperatures: 300 and 600 °C. XANES measurements confirmed that Cu was in the +1 valence state for all as-grown samples. Preliminary EXAFS measurements also demonstrated that Cu incorporated into a Zn-atom position substitutionally. X-ray diffraction also indicated significant phase separation with the presence of both metallic Cu and CuO indicated for Cu concentrations >3×1021 cm−3.
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- 2003
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18. Incidence of contralateral patent processus vaginalis in relation to age at laparoscopic percutaneous extraperitoneal closure for pediatric inguinal hernia
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Wataru Sumida, Yoshio Watanabe, Kazuo Oshima, Naoko Komatsuzaki, and Hidemi Takasu
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Male ,medicine.medical_specialty ,Percutaneous ,Adolescent ,Hernia, Inguinal ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Humans ,Hernia ,In patient ,Laparoscopy ,Child ,Herniorrhaphy ,Aged ,Retrospective Studies ,medicine.diagnostic_test ,business.industry ,Incidence (epidemiology) ,Incidence ,Age Factors ,Patent processus vaginalis ,Infant ,General Medicine ,Middle Aged ,medicine.disease ,Institutional review board ,Surgery ,Inguinal hernia ,030220 oncology & carcinogenesis ,Child, Preschool ,030211 gastroenterology & hepatology ,Female ,business - Abstract
Laparoscopic percutaneous extraperitoneal closure (LPEC) allows the surgeon to look for contralateral patent processus vaginalis (CPPV) directly. We investigated the incidence of CPPV in relation to age at LPEC. Following Institutional Review Board approval, 1232 patients ranging in age from 2 months old to 15 years old (median 4.7 years), who underwent LPEC, were investigated retrospectively. Patients were divided into five groups based on their age at surgery: younger than 1, 1–2, 2–4, 4–6 years, and older than 6 years. The incidence of CPPV being detected by preoperative ultrasonography or laparoscopy was compared among these groups. Statistical analyses were performed using the Chi-square test or Cochran–Armitage trend test, and p
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- 2015
19. Growth of N-doped and Ga+N-codoped ZnO films by radical source molecular beam epitaxy
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Akimasa Yamada, Kakuya Iwata, Hidemi Takasu, Koji Matsubara, S. Niki, Ralf Hunger, Paul Fons, and Ken Nakahara
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Radical ,Doping ,Inorganic chemistry ,chemistry.chemical_element ,Substrate (electronics) ,Condensed Matter Physics ,Acceptor ,Nitrogen ,Inorganic Chemistry ,chemistry ,Materials Chemistry ,Gallium ,Indium ,Molecular beam epitaxy - Abstract
It has been theoretically predicted that the codoping of an acceptor (nitrogen) and a donor (aluminium, gallium, indium) in a 2 : 1 ratio will enable the fabrication of low resistivity p-type ZnO due to reduction of the Madelung energy making the nitrogen acceptor energy level shallower. We have been growing N-doped and Ga+N codoped ZnO films by radical-source molecular beam epitaxy. Nitrogen and oxygen radicals were separately supplied via radio-frequency radical cells. Nitrogen did not incorporate in ZnO films at the high substrate temperature of 600°C. Lower substrate temperatures were necessary for nitrogen incorporation. From the fact that the nitrogen concentration also depended on the Zn fluxes, it is concluded that Zn-rich conditions are indispensable for nitrogen doping. The presence of Ga was observed to enhance nitrogen incorporation, one of the predicted effects of codoping. However, high Ga concentrations were found to lead to formation of the additional phase of ZnGa 2 O 4 in ZnO films.
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- 2002
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20. Electrical Properties of Nonvolatile Latches for New Logic Application
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Takashi Nakamura, Hidemi Takasu, and Yoshikazu Fujimori
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Materials science ,business.industry ,Electrical engineering ,Hardware_PERFORMANCEANDRELIABILITY ,Condensed Matter Physics ,Ferroelectricity ,Electronic, Optical and Magnetic Materials ,law.invention ,Capacitor ,Hardware_GENERAL ,Control and Systems Engineering ,law ,Hardware_INTEGRATEDCIRCUITS ,Materials Chemistry ,Ceramics and Composites ,Electrical and Electronic Engineering ,Data retention ,Operating speed ,Standby power ,business ,Scaling ,Hardware_LOGICDESIGN ,Electronic circuit - Abstract
A novel nonvolatile latch with ferroelectric capacitors has been developed to reduce standby power of LSIs. This latch stores the data as a ferroelectric remanent polarization during power off without area penalty and operating speed degradation. Test circuits have been fabricated to confirm characteristics of the latch. The data retention and the stable recall procedure have been confirmed. This paper also describes scaling projection of this technique.
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- 2002
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21. A XANES Study of Cu Valency in Cu-Doped Epitaxial ZnO
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Ken Nakahara, Akimasa Yamada, Hidemi Takasu, Kakuya Iwata, S. Niki, Paul Fons, and Koiji Matsubara
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Valence (chemistry) ,Argon ,Annealing (metallurgy) ,Inorganic chemistry ,Valency ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,Epitaxy ,XANES ,Electronic, Optical and Magnetic Materials ,Metal ,chemistry ,visual_art ,visual_art.visual_art_medium ,Molecular beam epitaxy - Abstract
Near-edge X-ray absorption (XANES) at the Cu K-edge was employed to study the valency of Cu (a potential p-dopant) in Cu-doped ZnO grown by molecular beam epitaxy. For a similar chemical environment, a shift in the onset of absorption can be interpreted as being due to a change in effective valency. We have studied this shift for both as-grown and argon ambient annealed (1000°C, 30 min) Cu-doped ZnO samples. The valency shift was measured against ab-initio standards calculated using feff8 as well as the standard samples Cu 2 O (+1 valence) and CuO (+2 valence). It was found for the flux region explored here that as-incorporated Cu assumes an effective valence of approximately +1 which increases towards +2 upon a 1000 °C argon ambient anneal. X-ray diffraction also shows the presence of both metallic Cu and Cu 2 O depending upon growth and annealing conditions.
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- 2002
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22. ZnO Films Grown on Si substrate by Radical Source MBE
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A. Yamada, Paul Fons, K. Matsubara, Kakuya Iwata, K. Nakahata, Shigeru Niki, and Hidemi Takasu
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Materials science ,Mechanical Engineering ,Electrical and Electronic Engineering - Published
- 2002
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23. Spatial composition fluctuations in blue-luminescent ZnCdO semiconductor films grown by molecular beam epitaxy
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Shigeo Fujita, Tetsuhiro Tanabe, Tsuyoshi Takagi, Takeshi Kubo, Keiichiro Sakurai, Shizuo Fujita, Daisuke Kajita, and Hidemi Takasu
- Subjects
X-ray spectroscopy ,Photoluminescence ,business.industry ,Chemistry ,Analytical chemistry ,Condensed Matter Physics ,segregation ,Inorganic Chemistry ,Semiconductor ,semiconducting IIVI materials ,Transmission electron microscopy ,molecular beam epitaxy ,Materials Chemistry ,Optoelectronics ,blue luminescence ,business ,Luminescence ,Chemical composition ,zinc compounds ,Solid solution ,Molecular beam epitaxy - Abstract
The optical and structural properties of textured ZnCdO films that exibit a newly found distinct blue luminescence have been investigated. Microscopic compositional fluctuations of Cd, associated with hexagonal grain structures, were observed. Models for the blue-luminescence process are proposed.
- Published
- 2002
24. Catheter-related bloodstream infection in patients with motility disorder of the alimentary tract
- Author
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Yoshio Watanabe, Kazuo Oshima, Hidemi Takasu, and Wataru Sumida
- Subjects
Adult ,Male ,medicine.medical_specialty ,Parenteral Nutrition ,Adolescent ,Digestive System Diseases ,Comorbidity ,Young Adult ,Catheters, Indwelling ,Japan ,Risk Factors ,Internal medicine ,Bloodstream infection ,Pediatric surgery ,medicine ,Humans ,In patient ,Child ,Retrospective Studies ,Cross Infection ,business.industry ,Medical record ,Infant, Newborn ,Motility disorder ,Infant ,General Medicine ,Surgery ,Catheter ,Parenteral nutrition ,Catheter-Related Infections ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,Female ,Complication ,business ,Gastrointestinal Motility ,Digestive System - Abstract
Catheter-related bloodstream infection (CRBSI) is a serious complication associated with parenteral nutrition (PN). We retrospectively examined the features of CRBSI in patients with motility disorder (MD) by reviewing medical records.Patients who received PN for more than 100 days in our hospital between January 2009 and September 2013 were reviewed. They were divided into two groups based on the presence or absence of MD. The frequency of CRBSI and the pathogenic organisms detected were compared. Statistical analysis was performed with the Mann-Whitney U test or Fisher's exact test. P0.05 was considered significant.Six patients had MD (MD group) and four patients had short bowels without MD (SB group). The median frequencies of CRBSI were 12.6 per 1,000 catheter-days in the MD group and 2.3 in the SB group (P = 0.027). The percentage of Gram-negative bacilli in all pathogenic organisms was 61% in the MD group and 22% in the SB group (P = 0.036).We found CRBSI was more frequent and Gram-negative bacilli were more common in patients with MD. Stasis in the alimentary tract and subsequent bacterial overgrowth appear to be risk factors for CRBSI. Therefore, it is crucial to seek treatments not to cause intestinal stasis.
- Published
- 2014
25. Ferroelectric memories and their applications
- Author
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Hidemi Takasu
- Subjects
Interconnection ,Hardware_MEMORYSTRUCTURES ,business.industry ,Computer science ,Electrical engineering ,Integrated circuit ,Condensed Matter Physics ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Programmable logic array ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Non-volatile memory ,Programmable logic device ,Reliability (semiconductor) ,law ,Electrical and Electronic Engineering ,business ,Field-programmable gate array - Abstract
In the near future, the ferroelectric memory technology will be taken into reconfigurable devices as programmable interconnect switches besides being used as embedded memories. These ferroelectric memory-based reconfigurable devices can be used as dynamic programmable gate arrays (DPGA), which can be reconfigured from their original logic in a system under an operation mode.
- Published
- 2001
- Full Text
- View/download PDF
26. Growth and characterization of undoped ZnO films for single crystal based device use by radical source molecular beam epitaxy (RS-MBE)
- Author
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R. Hunger, A. Yamada, S. Niki, K. Matsubara, Paul Fons, Kakuya Iwata, Ken Nakahara, and Hidemi Takasu
- Subjects
Chemistry ,business.industry ,Annealing (metallurgy) ,Pole figure ,Condensed Matter Physics ,Epitaxy ,Inorganic Chemistry ,Crystallography ,Silicon on sapphire ,Materials Chemistry ,Sapphire ,Optoelectronics ,Thin film ,business ,Single crystal ,Molecular beam epitaxy - Abstract
The integrated use of (1120) α-plane sapphire substrates and high temperature growth with low temperature buffer layers have led to high quality undoped ZnO epitaxial films with mobilities as high as 120 cm 2 V -1 s -1 and residual carrier concentrations as low as 7.6 x 10 16 cm -3 . Pole figure measurements reveal that a-plane sapphire substrates are effective for the elimination of 30 rotation domains, which usually appear using c-plane sapphire substrates. In particular, when using c-plane sapphire substrates annealing at 1000°C in O 2 with c/2-height surface steps, the X-ray diffraction pole figure peak intensity related to these rotation domains increased. The use of low temperature buffer layers allow high temperature ZnO growth on sapphire, as initial ZnO growth does not occur at high initial growth temperature.
- Published
- 2001
- Full Text
- View/download PDF
27. Nucleation and growth of ZnO on sapphire substrates using molecular beam epitaxy
- Author
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Koiji Matsubara, S. Niki, Hidemi Takasu, Tetsuhiro Tanabe, Paul Fons, Atsuo Yamada, Kakuya Iwata, and Ken Nakahara
- Subjects
Diffraction ,Chemistry ,Nucleation ,Analytical chemistry ,Substrate (electronics) ,Condensed Matter Physics ,Epitaxy ,X-ray absorption fine structure ,Inorganic Chemistry ,Crystallography ,Materials Chemistry ,Sapphire ,Thin film ,Molecular beam epitaxy - Abstract
It has been recently demonstrated that it is possible to eliminate 30° rotation twins in c-oriented epitaxial ZnO films by growing on the (1 1 2 0) face of sapphire despite the apparent symmetry mismatch between the (6-fold) epilayer and the (2-fold) substrate. To further elucidate the details of the growth process, we have investigated the initial stages of growth of ZnO on (1 1 2 0) sapphire using molecular beam epitaxy. Films of approximately 3, 5, 8, 10, 20, 100, and 600 nm thickness were investigated by in situ reflection high-energy diffraction, high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and extended X-ray absorption (XAFS). XAFS indicates that there is no discernible change in nearest-neighbor distance with film thickness. On the other hand, HRXRD measurements indicate an ∼1% increase in the c-lattice constant with decreasing film thickness. XAFS measurements of the second nearest-neighbor structural disorder were observed to increase sharply for the thinnest films implying that distortion of bond angles is responsible for the increase in the c-axis observed by HRXRD. HRXRD reciprocal area maps of the symmetric ZnO (0 0 0 2) reflection indicate the onset of diffuse scattering from 20 nm, while AFM indicates a concurrent change in surface morphology suggesting a change in the growth process for t>∼20 nm .
- Published
- 2001
- Full Text
- View/download PDF
28. Improvement of Electrical Properties in ZnO Thin Films Grown by Radical Source(RS)-MBE
- Author
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Kakuya Iwata, Koiji Matsubara, Hidemi Takasu, Ken Nakahara, Akimasa Yamada, S. Niki, and Paul Fons
- Subjects
Materials science ,business.industry ,Optoelectronics ,Thin film ,Condensed Matter Physics ,business ,Electronic, Optical and Magnetic Materials - Published
- 2000
- Full Text
- View/download PDF
29. [Untitled]
- Author
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Hidemi Takasu
- Subjects
Hardware_MEMORYSTRUCTURES ,Materials science ,business.industry ,Sense amplifier ,Electrical engineering ,Semiconductor memory ,Condensed Matter Physics ,Ferroelectric capacitor ,Electronic, Optical and Magnetic Materials ,Non-volatile memory ,Hardware_GENERAL ,Mechanics of Materials ,Logic gate ,Ferroelectric RAM ,Materials Chemistry ,Ceramics and Composites ,Non-volatile random-access memory ,Electrical and Electronic Engineering ,Memory refresh ,business - Abstract
The ferroelectric memory is not only an ideal memory with clear advantages such as non-volatility, low power consumption, high endurance and high speed writing, but is also the most suitable device for memory embedded applications. Its manufacturing process makes it more compatible with the standard CMOS process than the traditional non-volatile memory process, since it does not require high voltage operation, and the ferroelectric process does not influence the characteristics of the CMOS devices used in logic cells, analog cells and core cells. In the spreading of Intellectual Property (IP) application for the LSI Industry, this embedded application takes on a more important role. In the near future, the ferroelectric memory technology will be taken into reconfigurable devices as programmable interconnect switches besides being used as embedded memories. These ferroelectric memory based reconfigurable devices can be used as Dynamic Programmable Gate Array (DPGA), which are able to be reconfigured from their original logic in a system under an operation mode. New logic circuits will operated with lower power consumption or a resume function by introducing ferroelectric gated transistors or ferroelectric capacitors. Even though ferroelectric memory technology has many advantages, it is not popular yet, since, the conventional semiconductor process degrades the ferroelectric layer easily. The means to prevent degradation of ferroelectric films in the silicon wafer process will also be discussed.
- Published
- 2000
- Full Text
- View/download PDF
30. GaN-Based Trench Gate Metal Oxide Semiconductor Field Effect Transistors with Over 100 cm2/(V s) Channel Mobility
- Author
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Yasushi Nanishi, Hidemi Takasu, Shin Egami, Hirotaka Otake, and Hiroaki Ohta
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Transistor ,General Engineering ,General Physics and Astronomy ,Time-dependent gate oxide breakdown ,law.invention ,Metal ,Gate oxide ,law ,visual_art ,MOSFET ,visual_art.visual_art_medium ,Breakdown voltage ,Optoelectronics ,Field-effect transistor ,business ,Communication channel - Abstract
Enhancement-mode metal oxide semiconductor field effect transistors (MOSFETs) with trench gate structures have been developed. These MOSFETs show excellent DC characteristics with on-voltage of 5.1 V, i.e., enhancement-mode operation and extremely high channel mobilities of 133 cm2/(V s). This structure enables us to realize vertical switching devices with high breakdown voltage and highly integrated low on-resistance with the usage of excellent physical parameters of GaN. This excellent performance of these devices breaks though the realization of GaN-based power switching transistors.
- Published
- 2007
- Full Text
- View/download PDF
31. Ferroelectric embedded devices
- Author
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Akira Kamisawa, Hidemi Takasu, and Takashi Nakamura
- Subjects
Hardware_MEMORYSTRUCTURES ,Materials science ,business.industry ,Embedded memory ,Condensed Matter Physics ,Ferroelectricity ,Ferroelectric capacitor ,Electronic, Optical and Magnetic Materials ,law.invention ,Non-volatile memory ,Capacitor ,Hardware_GENERAL ,Control and Systems Engineering ,Memory cell ,law ,Embedded system ,Materials Chemistry ,Ceramics and Composites ,Smart card ,Electrical and Electronic Engineering ,business - Abstract
Ferroelectric memory is expected not only for a standard memory but also for embedded memories in logic LSIs such as smart cards and microcomputers, because it's electrical characteristics and process compatibility are adequate for embedded. For embedded devices, a high speed operation and a reduction in memory cell area are required. In order to apply the ferroelectric memory to the embedded devices widely, a multi level metallization (for high speed operation), a stacked capacitor cell (for reduction the cell area) and other techniques are necessary. In this paper, our approach for the ferroelectric embedded device will be presented.
- Published
- 1998
- Full Text
- View/download PDF
32. Dislocation-Freem-Plane InGaN/GaN Light-Emitting Diodes onm-Plane GaN Single Crystals
- Author
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Hidemi Takasu, Masayuki Sonobe, Kuniyoshi Okamoto, Jun Ichihara, Hiroaki Ohta, and Daisuke Nakagawa
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,General Engineering ,Stacking ,General Physics and Astronomy ,Nitride ,Electroluminescence ,Epitaxy ,law.invention ,Wavelength ,law ,Scanning transmission electron microscopy ,Optoelectronics ,Quantum efficiency ,business ,Light-emitting diode - Abstract
m-Plane (10-10) nonpolar InGaN-based light emitting diodes (LEDs) with no threading dislocations or stacking faults have been realized on m-plane GaN single crystals by conventional metal organic vapor phase epitaxy. The crystalline properties of the material, together with the structures of the LED devices, have been observed by scanning transmission electron microscopy. It is shown that dislocation-free nonpolar nitride layers with smooth surfaces can be obtained under growth conditions involving high V/III ratios, which are the optimized growth conditions for c-plane GaN. The peak wavelength of the electroluminescence emission obtained from the finished devices is 435 nm, which is in the blue region. The output power and the calculated external quantum efficiency are 1.79 mW and 3.1%, respectively, at a driving current of 20 mA.
- Published
- 2006
- Full Text
- View/download PDF
33. Integrated ferroelectrics as a strategic device
- Author
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Hidemi Takasu
- Subjects
Dynamic random-access memory ,Hardware_MEMORYSTRUCTURES ,Materials science ,business.industry ,Sense amplifier ,Electrical engineering ,Semiconductor memory ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,law.invention ,Non-volatile memory ,Hardware_GENERAL ,Control and Systems Engineering ,law ,Computer data storage ,Materials Chemistry ,Ceramics and Composites ,Non-volatile random-access memory ,Electrical and Electronic Engineering ,Memory refresh ,business ,Computer memory - Abstract
The ferroelectric memory is the most suitable device for memory embedded applications. Its manufacturing process makes it more compatible with the standard CMOS process than the traditional non-volatile memory processes, due to device operation voltage requirements. In addition, it provides clear advantages such as non-volatility, lower power consumption, higher endurance on writing cycles and higher writing speed. The most significant benefits of the embedded ferroelectric memory are shown on contactless smart IC cards and RF-ID cards without battery backup, which will expand the electronic ID market in a variety of applications. A super high integration chip will not be produced without having any redundancy circuit on it. If the ferroelectric memory technology is applied to FPGA (field programmable gate array), however, this problem will be solved. The ferroelectric memory technology will lead to a new semiconductor device architecture, and will take the major place in the coming multi-media era.
- Published
- 1997
- Full Text
- View/download PDF
34. Lead content control of PLZT thin films prepared by RF magnetron sputtering
- Author
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Hidemi Takasu, A. Osawa, K. Nakamura, Koukou Suu, Takanori Ozawa, Akira Kamisawa, Michio Ishikawa, N. Tani, and Katsumi Sameshima
- Subjects
Argon ,Materials science ,Scanning electron microscope ,Analytical chemistry ,chemistry.chemical_element ,Sputter deposition ,Condensed Matter Physics ,Ferroelectricity ,Electronic, Optical and Magnetic Materials ,chemistry ,Control and Systems Engineering ,Sputtering ,Materials Chemistry ,Ceramics and Composites ,Radio frequency ,Electrical and Electronic Engineering ,Thin film ,Spectroscopy - Abstract
PLZT thin films were deposited on 6-inch Pt/Ti/SiO2/Si substrates by radio frequency (RF) magnetron sputtering using a multichamber type production system. The lead (Pb) content in low temperature deposited PLZT films was measured by ICP spectroscopy and structural properties of rapid thermally annealed PLZT films were characterized by X-ray diffraction and scanning electron microscopy. It is found that several sputtering parameters such as RF power, argon (Ar) gas flow and magnetic field were very effective to control the Pb content which is essential for obtaining good ferroelectric properties.
- Published
- 1997
- Full Text
- View/download PDF
35. Cinematic magnetic resonance enterography for non-organic abdominal pain in infants and children
- Author
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Yoshio, Watanabe, Hidemi, Takasu, Wataru, Sumida, and Kazuo, Ohshima
- Subjects
Male ,Intestinal Diseases ,Adolescent ,Child, Preschool ,Humans ,Magnetic Resonance Imaging, Cine ,Female ,Child ,Gastrointestinal Transit ,Abdominal Pain - Abstract
Recurrent non-organic abdominal pain is the most commonly diagnosed medical problem in children. However, excluding small bowel disease remains a challenge. We evaluated our exclusion criteria for organic small intestinal diseases in pediatric patients with recurrent non-organic abdominal pain using cinematic magnetic resonance (cine-MR) enterography.The non-intestinal organic (non-IO) group as classified by the Rome III criteria system and the intestinal organic (IO) group consisted of 81 and 19 patients, with 35 and 12 male and 46 and 7 female patients with an age range of 5-18 and 4-15 years (average 10.5 and 10.5 years), respectively. Cine-MR enterography was performed by dynamically balanced first-field-echo imaging with thick-slice water-selective excitation without breath holding. In our original small intestinal motility test, cine-MR enterography was taken at three different times (fasting state [P1], immediately after [P2] and 30 min after [P3] drinking liquid material), with images taken sequentially for 5 min at each time-point to evaluate the motion of water in the gastrointestinal tract. Positive findings for organic intestinal problems were concluded when persistent visible intestinal loops appeared in both the P1 and P2 phases.Cine-MR enterography showed 6/81 (7.4%) and 18/19 (94.7%) (P0.01) positive cases of organic intestinal problems in the non-IO and IO groups, respectively. Positive and negative predictive values of this examination were 78.3% and 97.4%, respectively.The unique capabilities of cine-MR enterography technology in this clinical setting render it an important additional diagnostic tool when specific disease management issues must be addressed.
- Published
- 2013
36. Degenerate layers in epitaxial ZnO films grown on sapphire substrates
- Author
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S. Niki, Hajime Shibata, Ken Nakahara, Koji Matsubara, Paul Fons, Kakuya Iwata, Hidemi Takasu, Akimasa Yamada, and Hitoshi Tampo
- Subjects
Electron mobility ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Hall effect ,Annealing (metallurgy) ,Degenerate energy levels ,Nitrogen doping ,Sapphire ,Optoelectronics ,business ,Epitaxy ,Buffer (optical fiber) - Abstract
ZnO films were grown on low-temperature (LT) buffer layers on sapphire a-plane (11–20) substrates by radical source molecular-beam epitaxy. The LT buffer layers were found to effect the electrical properties of subsequently grown undoped ZnO films, and their presence was found to be indispensable for the growth of films with low carrier concentrations and high mobilities. Temperature-dependent Hall measurements showed the existence of a degenerate region related to the LT buffer layers. It was found that the effects of degenerate layers could be reduced by using annealing treatments and nitrogen doping of the LT buffer layers. The dominant residual donor energy of 110 meV was found to be different than previously reported. The carrier concentration of a ZnO film fabricated using a nitrogen-doped buffer layer was 7.5×1016 cm−3 with a mobility of 132 cm2/V s at room temperature.
- Published
- 2004
- Full Text
- View/download PDF
37. Electrical properties of PZT thin films for memory application
- Author
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Takashi Nakamura, Hidemi Takasu, Yuichi Nakao, and Akira Kamisawa
- Subjects
Materials science ,Chemical substance ,business.industry ,Condensed Matter Physics ,Ferroelectricity ,Electronic, Optical and Magnetic Materials ,law.invention ,Capacitor ,Control and Systems Engineering ,law ,Electrode ,Materials Chemistry ,Ceramics and Composites ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,Science, technology and society ,business ,Layer (electronics) - Abstract
The development of ferroelectric memory device requires improvements in electrical characteristics such as fatigue, retention, imprint and other properties. Fatigue properties of PZT thin films were improved by using Pt/IrO2 or Ir/IrO2 used as electrodes, we reported. This report presents a study of the retention and the imprint characteristics of PZT thin films on various electrodes. Pt/IrO2 and Ir/IrO2 layer structures were used as electrodes of the PZT capacitors. In the case of using an Ir/IrO2 electrode, the improvements in electrical properties from the measurements of the retention and the imprint characteristics.
- Published
- 1995
- Full Text
- View/download PDF
38. Ferroelectric memory FET with Ir/IrO2 electrodes
- Author
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Takashi Nakamura, Yuichi Nakao, Hidemi Takasu, and Akira Kamisawa
- Subjects
Materials science ,business.industry ,Condensed Matter Physics ,Ferroelectricity ,Ferroelectric capacitor ,Electronic, Optical and Magnetic Materials ,Control and Systems Engineering ,Electrode ,Memory window ,Materials Chemistry ,Ceramics and Composites ,Ferroelectric thin films ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,business ,Layer (electronics) - Abstract
We proposed a MFMIS structure having a floating gate as a bottom electrode between a ferroelectric thin film and the gate SiO2. Conventional gate SiO2 can be used and ferroelectric thin films can be grown on bottom electrodes which have a good matching with the ferroelectric materials due to adopt the MFMIS structure. Ir and IrO2 on poly-Si were used as floating gate. When a IrO2 layer was formed between PZT and poly-Si, a high-quality PZT thin film was obtained and the PZT films show no fatigue up to 1012 cycles of switching pulses. From the ID-VG characteristics measurement for 1·2 μm P-ch MFMIS FET, the shift in Vth or the memory window for a bias sweep of ±15V was about 3·3V. The difference of ID-VD curves which corresponded to ID-VG characteristics were found between before and after a programming pulse was applied.
- Published
- 1995
- Full Text
- View/download PDF
39. Study on ferroelectric thin films for application to NDRO non-volatile memories
- Author
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Akira Kamisawa, Hidemi Takasu, Takashi Nakamura, and Yuichi Nakao
- Subjects
Materials science ,business.industry ,Sputter deposition ,Condensed Matter Physics ,Ferroelectricity ,Electronic, Optical and Magnetic Materials ,law.invention ,Capacitor ,Control and Systems Engineering ,law ,Electrode ,Materials Chemistry ,Ceramics and Composites ,Ferroelectric thin films ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,business ,Polarization (electrochemistry) ,Voltage - Abstract
In this paper we describe an experimental study on ferroelectric non-volatile memory. The test devices using a MFMIS (metal-ferroelectric-metal-insulator-semiconductor) structure were developed for 1-Tr-type NDRO (non-destructive readout) memory. PZT (Lead-zirconate-titanate) and PT (lead-titanate) thin films were deposited on various bottom electrodes by solgel method. As electrodes, Pt, Pt/Ti, Pt/Ti/Ta and Pt/IrO2 were deposited by RF magnetron sputtering. We found out that a variation in the electrodes caused drastic changes in the C-V characteristics and fatigue characteristics of MFMIS capacitors. The I-V characteristics of Pt/PZT/ Pt/SiO2/p-Si MFMIS FET showed a hysteresis loop and the direction of the loop corresponded to ferroelectric polarization in the PZT film. A 2.7 V memory window was achieved using a 6 V programming voltage. PZT thin films on Pt/IrO2 electrodes showed no fatigue after 1012 switching cycles.
- Published
- 1995
- Full Text
- View/download PDF
40. Novel High-sensitivity Broadband Image Sensor with CIGS Thin Films
- Author
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Takuji Maekawa, H. Sekiguchi, D. Ohnishi, T. Fujii, Hidemi Takasu, Shigeru Niki, O. Matsushima, Y. Ota, and T. Maeda
- Subjects
Materials science ,business.industry ,Broadband ,Optoelectronics ,Sensitivity (control systems) ,Image sensor ,Thin film ,business ,Copper indium gallium selenide solar cells - Published
- 2012
- Full Text
- View/download PDF
41. Silicon Carbide devices open a new era of power electronics
- Author
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Hidemi Takasu
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Power module ,Power electronics ,MOSFET ,Wide-bandgap semiconductor ,Silicon carbide ,Electronic engineering ,Schottky diode ,Engineering physics ,Power density ,Diode - Abstract
Silicon Carbide (SiC) devices have the potential to reduce energy losses in high power applications. However SiC devices have yet to achieve ideal performance levels. This paper presents SiC diodes and MOSFETs with advanced trench structures. These devices succeeded in improving performance by reduction of the internal electric field. Trench Schottky diodes are able to reduce forward voltage drop and double-trench MOSFETs show extremely low on-resistance. In addition, transfer-molded power modules using SiC devices demonstrated high temperature operation and high power density.
- Published
- 2012
- Full Text
- View/download PDF
42. Interactions between gallium and nitrogen dopants in ZnO films grown by radical-source molecular-beam epitaxy
- Author
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S. Niki, Kakuya Iwata, Koji Matsubara, Akimasa Yamada, Hidemi Takasu, Ralf Hunger, Ken Nakahara, and Paul Fons
- Subjects
Materials science ,Photoluminescence ,Physics and Astronomy (miscellaneous) ,Inorganic chemistry ,Doping ,Analytical chemistry ,chemistry.chemical_element ,Epitaxy ,Acceptor ,chemistry ,X-ray crystallography ,Gallium ,Indium ,Molecular beam epitaxy - Abstract
It has been recently predicted that the co-doping of an acceptor (nitrogen) and a donor (aluminum, gallium, indium) in a 2:1 ratio will dope ZnO p-type due to a reduction in the Madelung energy making the nitrogen acceptor energy level more shallow. We have been growing gallium and nitrogen co-doped ZnO films by radical-source molecular-beam epitaxy by use of oxygen and nitrogen radicals supplied via rf radical source cells. Diode-like current–voltage characteristics and donor acceptor pair-like photoluminescence emission were observed for a Ga and N doped ZnO film grown on an undoped ZnO buffer layer. However, Hall measurements revealed that the conductivity was n-type. Formation of a non-ZnO phase in the sample was confirmed by secondary ion mass spectroscopy and x-ray diffraction measurements. Zn and Zn+O secondary ion intensities fell sharply by two orders of magnitude in going from the undoped ZnO layer to the highly co-doped ZnO. X-ray diffraction measurements indicated the formation of ZnGa2O4.
- Published
- 2001
- Full Text
- View/download PDF
43. Current Development Status and Future Challenges of FeRAM
- Author
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T. Kanaya, Suzuki Tatsuya, Masato Moriwake, N. Kinouchi, Yoshinobu Ichida, Hidemi Takasu, J. Iida, K. Ashikaga, Z. Zhiyong, Yoshikazu Fujimori, Hiromitsu Kimura, M. Kojima, T. Date, T. Ozawa, H. Ito, D. Notsu, and T. Fuchikami
- Subjects
Materials science ,Ferroelectric RAM ,Systems engineering ,Nanotechnology ,Current (fluid) - Published
- 2010
- Full Text
- View/download PDF
44. A preliminary report on the significance of excessively long segment congenital hypoganglionosis management during early infancy
- Author
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Wataru Sumida, Yoshio Watanabe, and Hidemi Takasu
- Subjects
Male ,medicine.medical_specialty ,Colon ,medicine.medical_treatment ,Biopsy ,Jejunostomy ,Colon surgery ,Ileum ,Medicine ,Humans ,Pathological ,Retrospective Studies ,medicine.diagnostic_test ,business.industry ,Sigmoid colon ,Infant ,Retrospective cohort study ,General Medicine ,Hypoganglionosis ,Surgery ,medicine.anatomical_structure ,Jejunum ,Treatment Outcome ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,Female ,Ganglia ,business ,Liver function tests ,Digestive System Abnormalities - Abstract
Background/Purpose Excessively long segment of congenital hypoganglionosis is rare, and therapeutic strategies to treat this disorder are not well established. The purpose of this study is to describe the significance of management in the neonatal and early infancy period. Patients and Methods Four patients (aged 1-4 years) with hypoganglionosis were selected for this study, of which 3 were treated at our hospital. In the initial treatment of 3 cases, an intraoperative pathological diagnosis was made on the basis of findings from simultaneous biopsies taken from the jejunum and sigmoid colon. Retrospective reviews of these patients were performed. Results Initial double-barrel jejunostomy at less than 50 cm from the ligament of Treitz allowed patients to start oral nutrition within a week following surgery. Subsequent refashioning of the initial jejunostomy to the Bishop-Koop type was performed at 3 to 6 months of age. Intravenous hyperalimentation was required to meet less than 50% of nutritional requirements, and patients were able to maintain their body weight within 1.5 SD of the normal mean body weight. Liver function test results were also within normal limits in the 3 patients treated at our hospital. Conclusion Early diagnosis and treatment may help improve the management of patients in the early stages of hypoganglionosis.
- Published
- 2010
45. Mg x Zn 1-x O epitaxial films grown on ZnO substrates by molecular beam epitaxy
- Author
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Akira Ohtomo, Takeyoshi Onuma, Hidemi Takasu, Atsushi Tsukazaki, Shunsuke Akasaka, Kentaro Tamura, Ken Nakahara, Tetsuhiro Tanabe, Shigefusa F. Chichibu, Hiroyuki Yuji, Atsushi Sasaki, and Masashi Kawasaki
- Subjects
Photoluminescence ,Materials science ,Monolayer ,Analytical chemistry ,Mineralogy ,Substrate (electronics) ,Thin film ,Luminescence ,Epitaxy ,Stoichiometry ,Molecular beam epitaxy - Abstract
Thin films of ZnO and Mg x Zn 1-x O were epitaxially grown on Zn-polar ZnO substrates by plasma assisted molecular beam epitaxy. The miscut of c-plane ZnO substrates toward the [1-100] axis direction leads to a flat substrate surface with straight step edges. The growth mode of epitaxial ZnO films significantly depended on the growth temperature, and a substrate temperature over 800°C was needed for flat film surfaces with monolayer-height steps. Photoluminescence (PL) peak originating from the n = 2 state of A-free excitons was observed at 12 K for the ZnO films grown under stoichiometric and O-rich growth conditions. Mg x Zn 1-x O films were also fabricated under Zn-rich conditions. The film surface exhibited a step-and-terrace structure. The effective PL lifetime of Mg 0.08 Zn 0.92 O film was as long as 1.9 ns, which is the highest value ever reported, presumably due to a high purity level of the film.
- Published
- 2008
- Full Text
- View/download PDF
46. Novel Solid-State Spatial Light Modulator on Integrated Circuits for High-Speed Applications with Electro-Optic Thin Film
- Author
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Suzuki Tatsuya, Hiromitsu Kimura, Takaaki Fuchikami, Yoshikazu Fujimori, Hidemi Takasu, Tsuyoshi Fujii, Masato Moriwake, and D. Nishinohara
- Subjects
Microelectromechanical systems ,Liquid-crystal display ,Spatial light modulator ,Materials science ,Pixel ,business.industry ,Integrated circuit ,Chip ,Lead zirconate titanate ,Optical switch ,law.invention ,chemistry.chemical_compound ,Optics ,chemistry ,law ,business - Abstract
Novel solid-state spatial light modulator (SLM) is developed. An electro-optic spatial ligNovel solid-state spatial light modulator (SLM) is developed. An electro-optic spatial light modulator (EOSLM) has advantages of high-speed operation, solid-state structure and easy integration with silicon LSIs in comparison with liquid crystal displays (LCD) and micro-electro-mechanical system (MEMS) displays. We propose a kind of Fabry-Perot type planer optical pixel to achieve high optical efficiency and high aperture ratio. The use of sol-gel technique makes it possible to fabricate optically smooth 800nm-fhick lead zirconate titanate (PZT) films, which results in sufficient transparency for the three primary colors of visible light. The large electro-optic effects of Deltan=0.026 is confirmed, and the optical switching response of 7ns is fastest compared with that have ever been reported. The prototype 180x180 SLM chip, which includes pixel driver circuits, is fabricated and successfully demonstrated. ht modulator (EOSLM) has advantages of high-speed operation, solid-state structure and easy integration with silicon LSIs in comparison with liquid crystal displays (LCD) and micro-electro-mechanical system (MEMS) displays. We propose a kind of Fabry-Perot type planer optical pixel to achieve high optical efficiency and high aperture ratio. The use of sol-gel technique makes it possible to fabricate optically smooth 800nm-fhick lead zirconate titanate (PZT) films, which results in sufficient transparency for the three primary colors of visible light. The large electro-optic effects of Deltan=0.026 is confirmed, and the optical switching response of 7ns is fastest compared with that have ever been reported. The prototype 180x180 SLM chip, which includes pixel driver circuits, is fabricated and successfully demonstrated.
- Published
- 2007
- Full Text
- View/download PDF
47. Implementation of a Standby-Power-Free CAM Based on Complementary Ferroelectric-Capacitor Logic
- Author
-
Hidemi Takasu, Hiromitsu Kimura, Takashi Nakamura, Takahiro Hanyu, and Shoun Matsunaga
- Subjects
Engineering ,Hardware_MEMORYSTRUCTURES ,Pass transistor logic ,business.industry ,Logic family ,Hardware_PERFORMANCEANDRELIABILITY ,Ferroelectric capacitor ,Non-volatile memory ,Integrated injection logic ,Hardware_GENERAL ,Logic gate ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,business ,Standby power ,Pull-up resistor ,Hardware_LOGICDESIGN - Abstract
A complementary ferroelectric-capacitor (CFC) logic-circuit style is proposed for a compact and standby-power-free content-addressable memory (CAM). Since the use of the CFC logic circuit in designing a CAM cell makes it possible to merge both logic and non-volatile storage elements into serially connected ferroelectric capacitors, the CAM becomes compact. The standby power of the CAM is completely eliminated because the supply voltage can be cut off with maintaining stored data in the CAM. The test chip is fabricated by using 0.35-mum ferroelectric CMOS, and the basic behavior can be also measured.
- Published
- 2007
- Full Text
- View/download PDF
48. Ferroelectric Technologies \newline for Portable Equipment
- Author
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Yoshikazu Fujimori, Takashi Nakamura, and Hidemi Takasu
- Subjects
business.industry ,Computer science ,Newline ,business ,Ferroelectricity ,Computer hardware - Published
- 2004
- Full Text
- View/download PDF
49. Ferroelectric-based functional pass-gate for fine-grain pipelined VLSI computation
- Author
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Hidemi Takasu, Takahiro Hanyu, Michitaka Kameyama, Hideaki Kimura, Takashi Nakamura, and Yoshikazu Fujimori
- Subjects
Very-large-scale integration ,Computer science ,Computation ,Hardware_PERFORMANCEANDRELIABILITY ,Polarization (waves) ,Ferroelectricity ,Ferroelectric capacitor ,Non-volatile memory ,Logic synthesis ,CMOS ,Hardware_GENERAL ,Logic gate ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Multiplier (economics) ,Hardware_ARITHMETICANDLOGICSTRUCTURES - Abstract
The state-transition scheme of remnant polarization in a ferroelectric capacitor performs storage and switching functions simultaneously with a functional pass-gate. As an example of fine-grain pipelined VLSI computation, a 250 MHz 54/spl times/54 b pipelined multiplier has 2.5 W estimated power dissipation in a 0.6 /spl mu/m ferroelectric/CMOS technology.
- Published
- 2003
- Full Text
- View/download PDF
50. Ferroelectric-based functional pass-gate for low-power VLSI
- Author
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Takahiro Hanyu, Hiromitsu Kimura, Hidemi Takasu, Takashi Nakamura, Yoshikazu Fujimori, and Michitaka Kameyama
- Subjects
Very-large-scale integration ,Engineering ,Hardware_MEMORYSTRUCTURES ,business.industry ,Electrical engineering ,Hardware_PERFORMANCEANDRELIABILITY ,Ferroelectric capacitor ,Non-volatile memory ,CMOS ,Hardware_GENERAL ,Low-power electronics ,Dynamic demand ,Ferroelectric RAM ,Hardware_INTEGRATEDCIRCUITS ,business ,Leakage (electronics) - Abstract
A ferroelectric-based functional pass-gate is proposed for low-power logic-in-memory VLSI which makes communication bottlenecks free. Since non-destructive storage and switching functions are merged into a ferroelectric capacitor, active-device counts become small, which reduces the dynamic power dissipation. The use of ferroelectric-based non-volatile storage makes leakage currents cut off. Applying the ferroelectric-based circuitry to binary CAM implementation results in about half dynamic power reduction and 1/22000 static power reduction, compared to a. CMOS implementation under 0.6 /spl mu/m ferroelectric/CMOS.
- Published
- 2003
- Full Text
- View/download PDF
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