Focusing on the linearity shortcoming on a bipolar low noise amplifier(LNA),a new 6 ~14GHz four stage SiGe HBT LNA is proposed.This amplifier adopts a method of gain allocation on multiple stages to avoid the limitati...Focusing on the linearity shortcoming on a bipolar low noise amplifier(LNA),a new 6 ~14GHz four stage SiGe HBT LNA is proposed.This amplifier adopts a method of gain allocation on multiple stages to avoid the limitation on linearity especially with the addition of negative gain on the third stage.To realize gain flatness,extra zero is introduced to compensate the gain roll-off formed by pole,and local shunt-shunt negative feedback is used to widen the bandwidth as well as optimize circuit' s noise.Simulated results have shown that in 6 ~14GHz,this circuit achieves noise figure(NF) less than 3dB,gain of 17.8dB(+0.2dB),input and output reflection parameters of less than- 10 dB,and the K factor is above 1.15.展开更多
The continuous reduction in sulfur content of fuels would lead to diesel fuel with poor lubricity which could re- sult in engine pump failure. In the present work, fatty acids were adopted as lubricity additives to lo...The continuous reduction in sulfur content of fuels would lead to diesel fuel with poor lubricity which could re- sult in engine pump failure. In the present work, fatty acids were adopted as lubricity additives to low-sulfur diesel fuel. It was attempted to correlate the molecular structures of fatty acids, such as carbon chain length, degree of saturation and hy- droxylation, to their lubricity enhancement, which was evaluated by the High-Frequency Reciprocating Rig （HFRR） meth- od. The efficiency order was supported by the density functional theory （DFT） calculations and the molecular dynamics （MD） simulations. The lubricity enhancing properties of fatty acids are mainly determined by the cohesive energy of adsorbed films furmed on iron surface. The greater the cohesive energy, the more efficiently the fatty acid would enhance the lubricity of low-sulfur diesel fuel.展开更多
Objective： To investigate the imaging features of primary hepatic leiomyoma. Methods： 3 patients of primary hepatic leiomyoma confirmed by pathology without immunodeficiency were retrospectively analyzed about CT an...Objective： To investigate the imaging features of primary hepatic leiomyoma. Methods： 3 patients of primary hepatic leiomyoma confirmed by pathology without immunodeficiency were retrospectively analyzed about CT and MRI findings, clinical and pathological correlation. 2 cases had routine CT scan, 2 cases had routine MRI. Results： 2 case CT scans showed low-density lesions, 2 cases MRI showed lesions with long T1 and long T2 signal. One case of uniform density and signal showed homogeneous enhancement; two cases showed uneven density and signal, of which one case was inhomogeneous enhancement. 3 cases presented pseudocapsule without hepatic cirrhosis and venous tumor thrombus. Pathology showed spindle tumor cell proliferation and capillary hyperplasia; one case showed central hyalinization and one case central liquefaction necrosis. Conclusion： Primary hepatic leiomyoma is a hypervascular tumor, and CT and MRI help in the diagnosis.展开更多
Objective: To observe the preventive role of Suxiao Jiuxin Pill (SX速效救心丸) on atherosclerosis (AS) and to probe into the mechanism in the atherosclerosis rat model. Methods: The AS rat model was established by a h...Objective: To observe the preventive role of Suxiao Jiuxin Pill (SX速效救心丸) on atherosclerosis (AS) and to probe into the mechanism in the atherosclerosis rat model. Methods: The AS rat model was established by a high fat diet and a large dose of calcium (vitamin D3, 0.6 million U/kg, i.p, once). Sixty healthy male adult Sprague-Dawlay (SD) rats were randomly divided into 6 groups, a normal control group (N), a model group (M), a SX low dose group (SXL), a SX middle dose group (SXM), a SX high dose group (SXH), and an atorvastatin group (ATO) (n=10 in each group). The rats in the treatment groups were given with the specific drugs from the first day by oral administration, and the normal control group and the model group were given with normal saline for 12 weeks. Afterwards, the content of malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and the content of oxidized low density lipoprotein (ox-LDL) in the serum were detected. In addition, the expression of peroxisome proliferator-activated receptor γ (PPARγ) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) proteins were tested by Western-blot method. Results: The serum ox-LDL and MDA level significantly decreased, SOD activity increased in the SX middle, high dose groups and the atorvastatin group compared to the model group (all P<0.05). While the expression of PPARγ and NF-κb proteins significantly decreased in the SX low, middle, high dose groups and the atorvastatin group compared to the model group (all P<0.01), with the best effect in the SX high dose group .These results indicate that SX could elevate the activity of serum SOD, decrease serum level of MDA and ox-LDL, and reduce the expression of PPARγ and NF-κB proteins. Conclusion: SX plays an important role in anti-inflammation and inhibition of oxidative stress, which possibly are the mechanism of its preventing and treating atherosclerosis.展开更多
基金Supported by the National Natural Science Foundation of China(No.61076101,61204092,61306033)
文摘Focusing on the linearity shortcoming on a bipolar low noise amplifier(LNA),a new 6 ~14GHz four stage SiGe HBT LNA is proposed.This amplifier adopts a method of gain allocation on multiple stages to avoid the limitation on linearity especially with the addition of negative gain on the third stage.To realize gain flatness,extra zero is introduced to compensate the gain roll-off formed by pole,and local shunt-shunt negative feedback is used to widen the bandwidth as well as optimize circuit' s noise.Simulated results have shown that in 6 ~14GHz,this circuit achieves noise figure(NF) less than 3dB,gain of 17.8dB(+0.2dB),input and output reflection parameters of less than- 10 dB,and the K factor is above 1.15.
基金supported by the Fundamental Research Funds for the Central Universities of China(11CX06036A)
文摘The continuous reduction in sulfur content of fuels would lead to diesel fuel with poor lubricity which could re- sult in engine pump failure. In the present work, fatty acids were adopted as lubricity additives to low-sulfur diesel fuel. It was attempted to correlate the molecular structures of fatty acids, such as carbon chain length, degree of saturation and hy- droxylation, to their lubricity enhancement, which was evaluated by the High-Frequency Reciprocating Rig （HFRR） meth- od. The efficiency order was supported by the density functional theory （DFT） calculations and the molecular dynamics （MD） simulations. The lubricity enhancing properties of fatty acids are mainly determined by the cohesive energy of adsorbed films furmed on iron surface. The greater the cohesive energy, the more efficiently the fatty acid would enhance the lubricity of low-sulfur diesel fuel.
文摘Objective： To investigate the imaging features of primary hepatic leiomyoma. Methods： 3 patients of primary hepatic leiomyoma confirmed by pathology without immunodeficiency were retrospectively analyzed about CT and MRI findings, clinical and pathological correlation. 2 cases had routine CT scan, 2 cases had routine MRI. Results： 2 case CT scans showed low-density lesions, 2 cases MRI showed lesions with long T1 and long T2 signal. One case of uniform density and signal showed homogeneous enhancement; two cases showed uneven density and signal, of which one case was inhomogeneous enhancement. 3 cases presented pseudocapsule without hepatic cirrhosis and venous tumor thrombus. Pathology showed spindle tumor cell proliferation and capillary hyperplasia; one case showed central hyalinization and one case central liquefaction necrosis. Conclusion： Primary hepatic leiomyoma is a hypervascular tumor, and CT and MRI help in the diagnosis.
文摘Objective: To observe the preventive role of Suxiao Jiuxin Pill (SX速效救心丸) on atherosclerosis (AS) and to probe into the mechanism in the atherosclerosis rat model. Methods: The AS rat model was established by a high fat diet and a large dose of calcium (vitamin D3, 0.6 million U/kg, i.p, once). Sixty healthy male adult Sprague-Dawlay (SD) rats were randomly divided into 6 groups, a normal control group (N), a model group (M), a SX low dose group (SXL), a SX middle dose group (SXM), a SX high dose group (SXH), and an atorvastatin group (ATO) (n=10 in each group). The rats in the treatment groups were given with the specific drugs from the first day by oral administration, and the normal control group and the model group were given with normal saline for 12 weeks. Afterwards, the content of malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and the content of oxidized low density lipoprotein (ox-LDL) in the serum were detected. In addition, the expression of peroxisome proliferator-activated receptor γ (PPARγ) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) proteins were tested by Western-blot method. Results: The serum ox-LDL and MDA level significantly decreased, SOD activity increased in the SX middle, high dose groups and the atorvastatin group compared to the model group (all P<0.05). While the expression of PPARγ and NF-κb proteins significantly decreased in the SX low, middle, high dose groups and the atorvastatin group compared to the model group (all P<0.01), with the best effect in the SX high dose group .These results indicate that SX could elevate the activity of serum SOD, decrease serum level of MDA and ox-LDL, and reduce the expression of PPARγ and NF-κB proteins. Conclusion: SX plays an important role in anti-inflammation and inhibition of oxidative stress, which possibly are the mechanism of its preventing and treating atherosclerosis.
