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ABSTRACT: A combination of antihypertensive agents can better control blood pressure and reduce the number and severity of side effects
than a monotherapy. Since both CCBs (calcium channel blockers) and ARBs (angiotensin II receptor type-1 blockers) are current
and effective antihypertensive drugs, this study assessed the synergistic antihypertensive effects as well as the optimal
combination ratio of these two drugs. Amlodipine (3 mg/kg) or losartan (30 mg/kg) alone or a combination of each drug at a
ratio 1:10 and 1:20 was administered orally to spontaneously hypertensive rats (SHR). A four-week treatment of either 3 mg/kg
amlodipine or 30 mg/kg losartan alone decreased the systolic blood pressure (SBP). However, their combination significantly
lowered the SBP from the 3rd week, and there was a positive correlation between this reduction in blood pressure and the improvement in arterial endothelium-dependent
relaxation. In addition, the combination therapy (1:20) decreased both the cardiac mass and left ventricular weight to a greater
extent than with either amlodipine or losartan alone. The collagen content in the cardiac tissue was also significantly lower
after the 4-week combination therapy (1:10). These results suggest that the combined use of amlodipine and losartan might
be more effective in treating hypertension than a monotherapy.
Archives of Pharmacal Research 04/2012; 32(3):353-358. · 1.59 Impact Factor
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International Symposium on Circuits and Systems (ISCAS 2010), May 30 - June 2, 2010, Paris, France; 01/2010
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ABSTRACT: A Ka-band monolithic microwave integrated circuit (MMIC) oscillator was implemented by using a coplanar waveguide photonic bandgap (PBG) resonator and a 0.1-μm GaAs pseudomorphic high electron mobility transistor. A coplanar labyrinthine one-dimensional PBG resonator was used for reduction in MMIC size. The fabricated MMIC oscillator had an output power of 6.5dBm at 30.3GHz and a free-running phase noise of -80dBc/Hz at 100-kHz offset.
IEEE Microwave and Wireless Components Letters 12/2005; · 1.72 Impact Factor
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ABSTRACT: The vascular changes associated with early diabetic retinopathy, which include the formation of microaneurysms and acellular capillaries, vessel dilation, vascular endothelial growth factor expression, were investigated experimentally in streptozotocin-induced diabetic rats treated with antioxidants: troxerutin (trihydroxy-ethylrutoside, CAS 7085-55-4), Vaccinium myrtillus, and calcium dobesilate (hydroquinone calcium sulfonate, CAS 20123-80-2). The development and progression of retinopathy was followed using fundus photography. After 3 months, the rats were sacrificed and half of the eyes were prepared for neovascularization analysis, and the other half were used for VEGF (vascular endothelial growth factor) analysis. The results from fundus photography and ADPase (adenosine diphosphatase) staining were quantified by the percentage area of the retinal vasculature using a commercial image analyzer. The VEGF protein in the retinal homogenates was assessed using an ELISA (enzyme linked immunosorbent assay) kit and VEGF-mRNA by RT-PCR (reverse transcription polymerase chain reaction). In the ADPase stain, the retinal vascular percent area increased significantly in the diabetic control. Neovascularization and aneurysms were observed in the diabetic control and were attenuated by 50 mg/kg troxerutin, but the retinal vascular percentage area was not significantly different from the diabetic control. The VEGF protein concentration was higher in diabetic rats than in the nondiabetic rats (21.5 +/- 2.1 vs 27.7 +/- 5.8 pg/mg, p < 0.05), and this increase was attenuated by 10 mg/kg troxerutin (24.5 +/- 3.8 pg/mg, p < 0.05) and prevented by 50 mg/kg troxerutin (19.5 +/- 2.2 pg/mg, p < 0.05). However, there were no significant differences between the groups. The VEGF-mRNA density showed a increasing tendency by 20% in the diabetic rats compared with the non-diabetic rats (1.0 +/- 0.1 vs 1.2 +/- 0.1 VEGF/beta-actin), and this increase was corrected by 10 mg/kg troxerutin (1.0 +/- 0.1 VEGF/beta-actin), 50 mg/kg troxerutin (0.9 +/- 0.1 VEGF/beta-actin) and Vaccinium myrtillus (1.1 +/- 0.1 VEGF/beta-actin). Oxidative stress might be involved in the upregulation of retinal VEGF during early diabetes, and it is likely that troxerutin has comparatively effective antioxidant properties. Therefore, troxerutin might be a useful treatment for attenuating diabetic retinopathy.
Arzneimittel-Forschung 01/2005; 55(10):573-80. · 0.72 Impact Factor
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ABSTRACT: By utilizing a remote ultraviolet ozone source, a low-temperature (600–700 °C) radical-assisted oxidation (RAO) process to produce high-quality ultrathin (1.4–3.7 nm) gate oxides was successfully developed for the fabrication of high-performance SiGe/Si metal-oxide-semiconductor field effect transistors (MOSFETs). The oxide grown by this technique showed much improved leakage and breakdown properties, compared with that grown without ozone. The reactive oxygen species in the RAO process seemed to cure the unpaired bonds in oxide networks making them more robust and dense, without an increase in thermal budget. The Si0.8Ge0.2 p-channel MOSFET with a RAO gate oxide exhibited superior device and 1/f noise characteristics to that with a standard higher temperature furnace oxide. This was because of the suppressed Ge-related gate-oxide degradation at the reduced process temperature when the Si-cap layer was thinned to below 2 nm. These suggest that the RAO process is particularly suitable for SiGe/Si MOSFET devices requiring a high-quality and low-temperature oxidation process.
Semiconductor Science and Technology 05/2004; 19(7):792. · 1.72 Impact Factor
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ABSTRACT: The paper presents the investigation of the low- frequency noise characteristics of D-mode and E-mode 0.13 μm In<sub>0.65</sub>GaAs p-HEMT under influence of impact ionisation induced gate hole current. The D-mode p-HEMT having a InP Schottky gate showed Lorentzian low-frequency noise components and drift of corner frequency due to drain bias change, while the InAlAs gate E-mode p-HEMT showed no change in behaviour due to the reduction of gate hole current.
Semiconductor Device Research Symposium, 2003 International; 01/2004
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ABSTRACT: Presents a fully monolithic K-band MMIC voltage-controlled oscillator (VCO) implemented by using a 0.25 /spl mu/m AlGaAs/InGaAs pseudomorphic HEMT (p-HEMT) technology. The use of a half-wavelength miniaturized hairpin-shaped resonator and a three-terminal p-HEMT varactor was effective in reducing the chip size and simplifying fabrication processes of the microwave MMIC VCO without impairing the performance of the circuit. The VCO provides a typical output power of 11.5 dBm at 20.8 GHz and a free-running phase noise of -82 dBc/Hz at 100 kHz offset and -95 dBc/Hz at 1 MHz offset. It also shows a tuning range of 70 MHz with little reduction in output power and high yield properties. The chip size of the MMIC VCO is 1.5 /spl times/ 2.0 mm/sup 2/.
IEEE Microwave and Wireless Components Letters 07/2003; · 1.72 Impact Factor
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ABSTRACT: The 1/f noise in Si<sub>0.8</sub>Ge<sub>0.2</sub> pMOSFETs was found to be lower than in all-silicon (Si) pMOSFETs, before and after Fowler-Nordheim (F-N) stress. The minimum noise in the Si<sub>0.8</sub>Ge<sub>0.2</sub> pMOSFET occurred at the thinnest unconsumed Si-cap of approximately 2 nm, because of the reduced-oxide trap density (N<sub>ot</sub>) near the Fermi level (E<sub>F</sub>) in the device. However, all samples in this study, including the Si control and the Si<sub>0.8</sub>Ge<sub>0.2</sub> pMOSFETs with different unconsumed Si-cap thicknesses of 21-64 Å, revealed almost identical relative changes in 1/f noise due to the stress, despite the relatively wide range of initial noise values. This suggests identical relative changes in N<sub>ot</sub> at the E<sub>F</sub> in the devices during F-N stress.
IEEE Transactions on Electron Devices 05/2003; · 2.32 Impact Factor
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IEEE Transactions on Electron Devices 03/2003; 50:1152-1156. · 2.32 Impact Factor
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ABSTRACT: In<sub>0.5</sub>Ga<sub>0.5</sub>P/In<sub>x</sub>Ga<sub>1-x</sub>As
(x=0.33 and 0.40), pseudomorphic high electron mobility transistors
(p-HEMTs) having a channel layer over the critical layer thickness were
grown on patterned and nonpatterned GaAs substrates by using a
compound-source molecular beam epitaxy (MBE). Characteristics of the
highly strained InGaP/In<sub>x</sub>Ga<sub>1-x</sub>As (x=0.33 and 0.40)
p-HEMTs grown on patterned substrates were compared with those of
conventional InGaP/In<sub>0.22</sub>Ga<sub>0.78</sub>As p-HEMTs grown on
a nonpatterned substrate. The highly strained InGaP/In<sub>0.33</sub>Ga
<sub>0.67</sub>As p-HEMT showed substantial improvements in device
performances including DC (drain saturation current and
transconductance), microwave (f<sub>T</sub> and f<sub>max</sub>),
low-frequency noise (Hooge parameter), and high-frequency noise (minimum
noise figure and associated gain) characteristics compared with those of
the conventional InGaP/In<sub>0.22</sub>Ga<sub>0.78</sub>As p-HEMT. The
improvements in device performances of the highly strained
InGaP/In<sub>0.33</sub>Ga<sub>0.67</sub>As p-HEMT are attributed to the
improved transport property of the high-quality highly strained
In<sub>0.33</sub>Ga<sub>0.67</sub>As channel layer achieved by the use
of the patterned substrate growth. The results indicate the potential of
highly strained InGaP/In<sub>x</sub>Ga<sub>1-x</sub>As p-HEMTs having a
channel layer in excess of the critical layer thickness grown on
patterned GaAs substrates for use in high-performance microwave device
applications
IEEE Transactions on Electron Devices 04/2002; · 2.32 Impact Factor
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ABSTRACT: We first report the characteristics of InGaAs-oxide grown by a liquid phase oxidation using a gallium-ion-contained nitric acid solution and an oxygen plasma treatment and depletion-mode In<sub>0.53</sub>Ga<sub>0.47</sub>As- and InP-channel MOSFETs using the InGaAs-oxide. The characteristics of InGaAs-oxide showed low leakage current and small capacitance-voltage hysteresis. 1.5×50 μm<sup>2</sup> depletion-mode In<sub>0.53</sub>Ga<sub>0.47</sub>Asand InP-channel MOSFETs were fabricated by using a conventional optical lithography. The gate oxide was formed by a liquid phase oxidation of InGaAs ohmic cap layer and subsequently an oxygen plasma treatment after mesa etching and ohmic metallization. The drain current-voltage characteristics of In<sub>0.53</sub>Ga<sub>0.47</sub>As- and InP-channel MOSFETs showed a complete pinch-off and saturation. The f<sub>T</sub> and f<sub>max</sub> of the In<sub>0.53</sub>Ga<sub>0.47</sub>As-channel MOSFET were approximately 9 GHz and 10 GHz, respectively, and those of the InP-channel MOSFET were approximately 10.5 GHz and 70 GHz, respectively.
Indium Phosphide and Related Materials Conference, 2002. IPRM. 14th; 02/2002
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ABSTRACT: In this paper, we report on the low-frequency and microwave noise
characteristics of the highly strained
InGaP/In<sub>0.33</sub>Ga<sub>0.67</sub>As p-HEMTs grown on patterned
substrate and the conventional
InGaP/In<sub>0.22</sub>Ga<sub>0.78</sub>As p-HEMTs grown on
non-patterned substrate
Device Research Conference, 2001; 02/2001
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ABSTRACT: Highly strained In0.5Ga0.5P/In0.33Ga0.67As and conventional In0.5Ga0.5P/In0.22Ga0.78As pseudomorphic high electron mobility transistor (p-HEMT) structures were grown on patterned and non-patterned GaAs substrates, respectively, by using a compound-source molecular beam epitaxy. Microwave characteristics and low-frequency noise characteristics of the p-HEMTs were measured and compared. The highly strained InGaP/In0.33Ga0.67As p-HEMT grown on the patterned substrate showed more than 20% improvements in microwave performances including the transition frequency (fT) and the maximum oscillation frequency (fmax) compared with those of the conventional InGaP/In0.22Ga0.78As p-HEMT grown on the non-patterned substrate. The input noise spectral density and the Hooge parameter of the highly strained InGaP/In0.33Ga0.67As p-HEMT grown on the patterned substrate were more than an order of magnitude lower than those of the conventional InGaP/In0.22Ga0.78As p-HEMT grown on the non-patterned substrate. The improvements in microwave characteristics and low-frequency noise characteristics of the highly strained InGaP/In0.33Ga0.67As p-HEMT are attributed to the improvement in transport property of the highly strained In0.33Ga0.67As channel layer achieved by a patterned substrate growth. The results indicate the potential of highly strained p-HEMTs grown on patterned substrates for use in applications requiring improved microwave and low phase noise characteristics.
Solid-State Electronics.
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ABSTRACT: Effects of side recess on kink effect and transconductance (g<sub>m</sub>) frequency dispersion characteristics of 0.13μm InGaAs p-HEMTs having InAlAs and InP surface were investigated. The p-HEMT having a 300 nm recessed InP surface showed negligible kink effect and g<sub>m</sub> dispersion due to the reduction in surface-state induced trap density in the InP etch-stop and impact-ionization induced hole current (I<sub>g,hole</sub>).
Indium Phosphide and Related Materials, 2004. 16th IPRM. 2004 International Conference on;
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ABSTRACT: We report the characteristics of InGaAs-oxide implemented by using a liquid phase oxidation and an oxygen plasma treatment and its application to depletion-mode In0.53Ga0.47As-channel metal oxide field effect transistor (MOSFET). The InGaAs-oxide characterized by using X-ray photoelectron spectroscopy (XPS), capacitance–voltage measurements showed excellent oxide/semiconductor interface characteristics. Depletion-mode (1.5 × 50 μm2) In0.53Ga0.47As-channel MOSFET fabricated by using a conventional optical lithography showed a complete pinch-off and saturation characteristics. The fT and fmax of the In0.53Ga0.47As-channel MOSFET were approximately 9 GHz and 10 GHz, respectively. The low frequency noise spectra of the In0.53Ga0.47As-channel MOSFET showed 1/f noise characteristics. The maximum differential transconductance frequency dispersion (Δgm/gm0) appeared at T = 200 K and was measured to be as low as 9.0%. The results indicate the potential of the InGaAs-oxide implemented by using the liquid phase oxidation and oxygen plasma treatment for use in high-performance InP-based MOSFET applications.
Solid-State Electronics.
