58 research outputs found
Effect of high annealing temperature on giant tunnel magnetoresistance ratio of CoFeB/MgO/CoFeB magnetic tunnel junctions
We report tunnel magnetoresistance (TMR) ratios as high as 472% at room
temperature and 804% at 5 K in pseudo-spin valve (SV) CoFeB/MgO/CoFeB magnetic
tunnel junctions (MTJs) annealed at 450oC, which is approaching the
theoretically predicted value. By contrast, the TMR ratios for exchange-biased
(EB) SV MTJs with a MnIr antiferromagnetic layer are found to drop when they
are annealed at 450oC. Energy dispersive X-ray analysis shows that annealing at
450oC induces interdiffusion of Mn and Ru atoms into the MgO barrier and
ferromagnetic layers in EB-SV MTJs. Mechanisms behind the different annealing
behavior are discussed.Comment: 13 pages, 5 figure
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Simplification of large linear systems using two-step iterative method
The order of the practical system (e.g. nuclear power
plants, electrical power network and chemical plant) is
quite large. However, there are many limitations in computing
facilities for the large system. Because of these
limitations, it is often necessary to reduce the order of
the large system using an approximation.
Here the simple iterative technique which is free of
certain shortcomings of the previous method is proposed
for the approximation of large linear systems by a low-order
model. A measure of the goodness of the model is the
value of the integral-square error between the step responses
of the exact and the simplified system.
The proposed technique consists of a two-step iterative
scheme. In the first step, the optimum residues are
obtained by the minimization of the objective function,
while the poles (or eigenvalues) are kept constant. In
the second step, the poles (or eigenvalues) are optimized
while the residues remain fixed. This procedure is continued
cyclically until the objective function is satisfactorily
minimized.
The necessary and sufficient conditions for existence
of an optimum are satisfied in each step. The residues,
poles (or eigenvalues) and objective functions always converge
monotomically. The resulting reduced-order model
obtained by this method is stable if the original system is
stable. The method can be applied not only to single-variable
systems, but also to systems with repeated poles
(or eigenvalues) and to multivariable systems. The results
are superior to those obtained previously in the steady-state
and transient responses, and the value of the
integral-square error.
Illustrative examples are presented
Long-term survival after an aggressive surgical resection and chemotherapy for stage IV pulmonary giant cell carcinoma
BACKGROUND: Pulmonary giant cell carcinoma is one of the rare histological subtypes with pleomorphic, sarcomatoid or sarcomatous elements. The prognosis of patients with this tumor tends to be poor, because surgery, irradiation and chemotherapy are not usually effective. CASE PRESENTATION: We herein report a patient with pulmonary giant cell carcinoma with stage IV disease in whom aggressive multi-modality therapy resulted in a long-term survival. A 51-year-old male underwent an emergent operation with a partial resection of small intestinal metastases due to bleeding from the tumor. The patient also underwent a left pneumonectomy due to hemothorax as a result of the rapid growth of the primary tumor. Thereafter, two different regimens of chemotherapy and a partial resection for other site of small intestinal metastases and a splenectomy for splenic metastases were performed. The patient is presently doing well without any evidence of recurrence for 3 years after the initial operation. CONCLUSION: This is a first report of a rare case with stage IV pulmonary giant cell carcinoma who has survived long-term after undergoing aggressive surgical treatment and chemotherapy
Dependence of Giant Tunnel Magnetoresistance of Sputtered CoFeB/MgO/CoFeB Magnetic Tunnel Junctions on MgO Barrier Thickness and Annealing Temperatur
We investigated the dependence of giant tunnel magnetoresistance (TMR) on the
thickness of an MgO barrier and on the annealing temperature of sputtered
CoFeB/MgO/CoFeB magnetic tunnel junctions deposited on SiO2/Si wafers. The
resistance-area product exponentially increases with MgO thickness, indicating
that the quality of MgO barriers is high in the investigated thickness range of
1.15-2.4 nm. High-resolution transmission electron microscope images show that
annealing at 375 C results in the formation of crystalline CoFeB/MgO/CoFeB
structures, even though CoFeB electrodes are amorphous in the as-sputtered
state. The TMR ratio increases with annealing temperature and is as high as
260% at room temperature and 403% at 5 K.Comment: 12 pages, 5 figure
Malignant schwannoma of the upper mediastinum originating from the vagus nerve
BACKGROUND: Malignant schwannoma of the upper mediastinum originating from the vagus nerve is extremely rare. CASE PRESENTATION: A 46-year-old female was admitted for a left cervical mass which was associated with both hoarseness and Horner's syndrome. Chest computed tomography showed a mass extending from the left upper mediastinum to the left supraclavicular area. A fine needle aspiration cytological examination suggested primary lung cancer stage IIIB large cell carcinoma. After administering induction chemo-radiotherapy, a complete surgical resection was performed. The tumor was found to involve both the left vagus nerve and the left sympathetic nerve. Histological examination of the resected specimen revealed the tumor to be malignant schwannoma. CONCLUSION: Despite incorrect preoperative diagnosis, the multimodality treatment administered in this case, including induction chemo-radiotherapy and surgery, proved to be effective
Dependence of tunnel magnetoresistance on ferromagnetic electrode materials in MgO-barrier magnetic tunnel junctions
We investigated the relationship between the tunnel magnetoresistance (TMR)
ratio and the electrode structure in MgO-barrier magnetic tunnel junctions
(MTJs). The TMR ratio in a MTJ with Co40Fe40B20 reference and free layers
reached 355% at the post-deposition annealing temperature of Ta=400 degree C.
When Co50Fe50 or Co90Fe10 is used for the reference layer material, no high TMR
ratio was observed. The key to have high TMR ratio is to have highly oriented
(001) MgO barrier/CoFeB crystalline electrodes. The highest TMR ratio obtained
so far is 450% at Ta = 450 degree C in a pseudo spin-valve MTJ.Comment: 6 pages, 2 figures, 1 table. to be published in J. Magn. Magn. Mate
Prognostic value of visceral pleural invasion in resected non–small cell lung cancer diagnosed by using a jet stream of saline solution
AbstractObjectiveVisceral pleural invasion caused by non–small cell lung cancer is a factor in the poor prognosis of patients with that disease. We investigated the relationship between the diagnosis of visceral pleural invasion by using a jet stream of saline solution, which was previously reported as a new cytologic method to more accurately detect the presence of visceral pleural invasion, and prognosis.MethodsFrom January 1992 through December 1998, 143 consecutive patients with peripheral non–small cell lung cancer that appeared to reach the visceral pleura underwent a surgical resection at the Department of Thoracic Oncology, National Kyushu Cancer Center. The surface of the visceral pleura in patients undergoing lung cancer resection was irrigated with a jet stream of saline solution. The diagnosis of visceral pleural invasion was determined by means of either a pathologic examination or by means of a jet stream of saline solution. In addition, a cytologic examination of the pleural lavage fluid obtained immediately after a thoracotomy was evaluated.ResultsForty-nine (34%) resected tumors were identified as having visceral pleural invasion. The diagnosis of visceral pleural invasion in 31, 6, and 12 patients was determined by using a jet stream of saline solution alone, pathologic examination alone, or both, respectively. The visceral pleural invasion and positive findings of intrapleural lavage cytology were linked. Although there was no significant difference between the incidence of distant metastases in the patients with visceral pleural invasion and those without visceral pleural invasion, the incidence of local recurrence, especially regarding carcinomatous pleuritis (malignant pleural effusion, pleural dissemination, or both), in the patients with visceral pleural invasion was significantly higher than in those without visceral pleural invasion. The recurrence-free survival of patients with visceral pleural invasion was significantly shorter than that of patients without visceral pleural invasion (P = .004), even patients with stage I disease (P = .02). There was also a significant difference between the patients with or without visceral pleural invasion in the overall survival (P = .02). Visceral pleural invasion was independently associated with a poor recurrence-free survival on the basis of multivariate analyses (P = .03), as were sex (P = .03), age (P = 002), and the stage of the disease (P < .0001).ConclusionsThis study confirmed that the jet stream of saline solution method in addition to ordinary pathologic examination was useful for detecting visceral pleural invasion, which is considered to be one of the causes of local recurrence, especially in carcinomatous pleuritis
Current-induced magnetization switching in MgO barrier magnetic tunnel junctions with CoFeB based synthetic ferrimagnetic free layers
We investigated the effect of using a synthetic ferrimagnetic (SyF) free
layer in MgO-based magnetic tunnel junctions (MTJs) on current-induced
magnetization switching (CIMS), particularly for application to spin-transfer
torque random access memory (SPRAM). The employed SyF free layer had a
Co40Fe40B20/ Ru/ Co40Fe40B20 and Co20Fe60B20/Ru/Co20Fe60B20 structures, and the
MTJs(100x(150-300) nm^2) were annealed at 300oC. The use of SyF free layer
resulted in low intrinsic critical current density (Jc0) without degrading the
thermal-stability factor (E/kBT, where E, kB, and T are the energy potential,
the Boltzmann constant, and temperature,respectively). When the two CoFeB
layers of a strongly antiferromagnetically coupled SyF free layer had the same
thickness, Jc0 was reduced to 2-4x10^6 A/cm^2. This low Jc0 may be due to the
decreased effective volume under the large spin accumulation at the CoFeB/Ru.
The E/kBT was over 60, resulting in a retention time of over ten years and
suppression of the write current dispersion for SPRAM. The use of the SyF free
layer also resulted in a bistable (parallel/antiparallel) magnetization
configuration at zero field, enabling the realization of CIMS without the need
to apply external fields to compensate for the offset field.Comment: 6 page
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