Modeling of the roughness in micro-nano scale and its influence have not been fully investigated, however the roughness will cause amplitude and phase errors of the radiating slot, and decrease the precision and effic...Modeling of the roughness in micro-nano scale and its influence have not been fully investigated, however the roughness will cause amplitude and phase errors of the radiating slot, and decrease the precision and efficiency of the SWA in Ku-band. Firstly, the roughness is simulated using the electromechanical coupled（EC） model. The relationship between roughness and the antenna＇s radiation properties is obtained. For verification, an antenna proto- type is manufactured and tested, and the simulation method is introduced. According to the prototype, a contrasting experiment dealing with the flatness of the radiating plane is conducted to test the simulation method. The advantage of the EC model is validated by comparisons of the EC model and two classical roughness models （sine wave and fractal function）, which shows that the EC model gives a more accurate description model for roughness, the maxi- mum error is 13%. The existence of roughness strongly broadens the beamwidth and raises the side-lobe level of SWA, which is 1.2 times greater than the ideal antenna. In addition, effect of the EC model＇s evaluation indices is investigated, the most affected scale of the roughness is found, which is 1/10 of the working wavelength. The proposed research provides the instruction for antenna designing and manufacturing.展开更多
The novel Coronavirus Disease (nCOVID-19) is a highly contagious viral infection which emerged as “Pneumonia of Unknown Etiology” at Hubei province of Wuhan city in China. The health authorities provided a considera...The novel Coronavirus Disease (nCOVID-19) is a highly contagious viral infection which emerged as “Pneumonia of Unknown Etiology” at Hubei province of Wuhan city in China. The health authorities provided a considerable empirical evidence after this outbreak and it was notified that the causative virus, named Novel Coronavirus (subsequently SARS-CoV-2) is the culprit for progressively exerting grim effects not only on individual patients but also on the International public health, with high mutational tendencies. WHO declared nCOVID-19 as a Pandemic on 11<sup>th</sup> March 2020. The spike glycoprotein of SARS-CoV-2 plays a pivotal role in the entry of virus into the cell and it further interacts with ACE-II receptors which are widely distributed on the human cell surface especially on alveolar type II cells (AT-2) and endothelium. The mortality in nCOVID-19 patients is usually preceded by acute respiratory distress syndrome (ARDS) because of the cytokine storm. Advanced molecular biology and regenerative sciences renders a breakthrough in the treatment of severely ill nCOVID-19 patients with Mesenchymal Stem Cells (MSCs). Autologous or allogenic MSCs attenuate cytokine storm, improvise lung compliance, regulate inflammatory response, maintain functional alveoli microenvironment, promote endogenous regeneration and repair with no or minimal side effects. MSCs are naturally resistant to this novel Coronavirus. Even though it is corroborated with evidences from current clinical trials and pilot study, we emphasize the need for conducting more clinical trials with ethical consideration to prove the efficacy and safety of MSCs in combating nCOVID-19 infection and its complications.展开更多
To satisfy the measuring demands for the micro components of the industry, micro/nano probing systems with various ball tips have been developed. However, most of them cannot be used to measure the real micro geometri...To satisfy the measuring demands for the micro components of the industry, micro/nano probing systems with various ball tips have been developed. However, most of them cannot be used to measure the real micro geometrical features high precisely because the parameters of the ball tips are not appropriate. The ball tips with a diameter of less than 100 μm, a sphericity and eccentricity of far less than 1 μm are required urgently. A review on the state-of-the-art of ball tips of micro/nano probing systems is presented. The material characteristics and geometric parameters of now available ball tips are introduced sepa- rately. The existing fabrication methods for the ball tips are demonstrated and summarized. The ball tips＇ future trends, which are smaller diameter, better sphericity and smaller eccentricity, are proposed in view of the practical requirements of high-precision measurement for micro geometrical features. Some challenges have to be faced in future, such as the promotion and high-precision measurement for the small ball tip＇s sphericity and eccentricity. Fusion method without the gravity effect when the molten ball tip solidifying is a more suitable way to fabricate a small diameter ball tip together with a shaft.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51305322,51405364,51475348)
文摘Modeling of the roughness in micro-nano scale and its influence have not been fully investigated, however the roughness will cause amplitude and phase errors of the radiating slot, and decrease the precision and efficiency of the SWA in Ku-band. Firstly, the roughness is simulated using the electromechanical coupled（EC） model. The relationship between roughness and the antenna＇s radiation properties is obtained. For verification, an antenna proto- type is manufactured and tested, and the simulation method is introduced. According to the prototype, a contrasting experiment dealing with the flatness of the radiating plane is conducted to test the simulation method. The advantage of the EC model is validated by comparisons of the EC model and two classical roughness models （sine wave and fractal function）, which shows that the EC model gives a more accurate description model for roughness, the maxi- mum error is 13%. The existence of roughness strongly broadens the beamwidth and raises the side-lobe level of SWA, which is 1.2 times greater than the ideal antenna. In addition, effect of the EC model＇s evaluation indices is investigated, the most affected scale of the roughness is found, which is 1/10 of the working wavelength. The proposed research provides the instruction for antenna designing and manufacturing.
文摘The novel Coronavirus Disease (nCOVID-19) is a highly contagious viral infection which emerged as “Pneumonia of Unknown Etiology” at Hubei province of Wuhan city in China. The health authorities provided a considerable empirical evidence after this outbreak and it was notified that the causative virus, named Novel Coronavirus (subsequently SARS-CoV-2) is the culprit for progressively exerting grim effects not only on individual patients but also on the International public health, with high mutational tendencies. WHO declared nCOVID-19 as a Pandemic on 11<sup>th</sup> March 2020. The spike glycoprotein of SARS-CoV-2 plays a pivotal role in the entry of virus into the cell and it further interacts with ACE-II receptors which are widely distributed on the human cell surface especially on alveolar type II cells (AT-2) and endothelium. The mortality in nCOVID-19 patients is usually preceded by acute respiratory distress syndrome (ARDS) because of the cytokine storm. Advanced molecular biology and regenerative sciences renders a breakthrough in the treatment of severely ill nCOVID-19 patients with Mesenchymal Stem Cells (MSCs). Autologous or allogenic MSCs attenuate cytokine storm, improvise lung compliance, regulate inflammatory response, maintain functional alveoli microenvironment, promote endogenous regeneration and repair with no or minimal side effects. MSCs are naturally resistant to this novel Coronavirus. Even though it is corroborated with evidences from current clinical trials and pilot study, we emphasize the need for conducting more clinical trials with ethical consideration to prove the efficacy and safety of MSCs in combating nCOVID-19 infection and its complications.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675157,51475131)State Key Laboratory of Precision Measuring Technology and Instruments of China(Grant No.PIL1401)
文摘To satisfy the measuring demands for the micro components of the industry, micro/nano probing systems with various ball tips have been developed. However, most of them cannot be used to measure the real micro geometrical features high precisely because the parameters of the ball tips are not appropriate. The ball tips with a diameter of less than 100 μm, a sphericity and eccentricity of far less than 1 μm are required urgently. A review on the state-of-the-art of ball tips of micro/nano probing systems is presented. The material characteristics and geometric parameters of now available ball tips are introduced sepa- rately. The existing fabrication methods for the ball tips are demonstrated and summarized. The ball tips＇ future trends, which are smaller diameter, better sphericity and smaller eccentricity, are proposed in view of the practical requirements of high-precision measurement for micro geometrical features. Some challenges have to be faced in future, such as the promotion and high-precision measurement for the small ball tip＇s sphericity and eccentricity. Fusion method without the gravity effect when the molten ball tip solidifying is a more suitable way to fabricate a small diameter ball tip together with a shaft.
