To break the limitations of the multi-dimensional(M-D)vibration isolation(VI)platforms with the Stewart-Gough design,such as strongly coupling motions,excessive friction in connections,heavy weight,and limited workspa...To break the limitations of the multi-dimensional(M-D)vibration isolation(VI)platforms with the Stewart-Gough design,such as strongly coupling motions,excessive friction in connections,heavy weight,and limited workspace,this study processes a novel platform integrated by a stiffness-adjustable origami spring sub-structure and a parallel mechanism.The origami-based stiffness-adjustable spring realizes low-frequency VI,and the parallel mechanism symmetry design realizes motions decoupling.In the origami-based sub-leg,the parallel-stack-assembly(PSA)design mechanism with two Miura origami configurations is proposed to generate a symmetrical negative stiffness property.Paired with a linear positive stiffness spring,the origami-based sub-leg has wide-amplitude-high-static-low-dynamic stiffness(WA-HSLDS)characteristics in one direction.Then,with construction of the parallel mechanism connected with origami-based sub-legs,an M-D VI platform is achieved,whose motions in the vertical direction and yaw direction are decoupled with the motions in the other directions.Based on the dynamic model and incremental harmonic balance(IHB)with the arc-length continuation method,appropriate structural parameters in the parallel mechanism part are figured out,and the accurate transmissibility in different directions is defined,which gives the parametric influencing investigations for realization of low-frequency VI performances.Finally,experiments are conducted to validate the accuracy and feasibility of the theoretical methods,and to demonstrate the performance of M-D low-frequency isolation with load-carrying capacity of the proposed VI platform.The integration of the origami into the parallel mechanism results in a compact,efficient,and flexible platform with nonlinear adjustability,offering new possibilities for lightweight M-D VI,and developing the practical applications in high-precision platforms in ocean and aerospace environments.展开更多
Objective This study aimed to investigate the expression and clinical significance of serum lipoprotein(a) [LP(a)] in patients with gastric cancer. Methods Two hundred and twenty-two patients with gastric cancer(gastr...Objective This study aimed to investigate the expression and clinical significance of serum lipoprotein(a) [LP(a)] in patients with gastric cancer. Methods Two hundred and twenty-two patients with gastric cancer(gastric cancer group) were selected from 2015 to 2017 [mean age(58.40 ± 10.40) years], as were 101 healthy persons [normal age group, mean age(58.18 ± 11.42) years]. Fasting blood samples were collected and evaluated by immunoturbidimetry with a biochemical analyzer. LP(a) concentration was observed and its difference was compared. Results There was no significant correlation between LP(a) and tumor stage(P > 0.05). Compared with the control group, the level of LP(a) in the male gastric cancer group was significantly higher than that in the control group(P < 0.05). In the subgroup analysis, the level of LP(a) and abnormal rate showed an increasing trend among patients with stages I–IV gastric cancer. The level of LP(a) in poorly differentiated gastric cancer patients was higher than that in the high middle differentiation group(P < 0.05). There was no significant difference in LP(a) levels among patients with different pathological types of gastric cancer(P > 0.05). Conclusion LP(a) was correlated with the occurrence, development and differentiation of gastric cancer, but not with the pathological classification of gastric cancer. Serum LP(a) concentration may be used as an indicator for the staging and prognosis of gastric cancer, but the specific underlying mechanism remains to be further studied.展开更多
In this Letter, we demonstrate high-quality(Q), millimeter-size, and V-shaped calcium fluoride crystalline resonators for modal modification. To manufacture such resonators, we develop a home-made machining system and...In this Letter, we demonstrate high-quality(Q), millimeter-size, and V-shaped calcium fluoride crystalline resonators for modal modification. To manufacture such resonators, we develop a home-made machining system and explore a detailed process. With a dedicated polished container, three special polishing steps, including grinding, smoothing, and polishing, are employed to achieve the required surface smoothness, which is characterized by less than 3 nm. An ultra-high-Q factor exceeding 108 is obtained by a coupled tapered fiber.In addition, a customized packaged structure for our disk resonator is achieved. The Q maintenance and stable spectrum are realized by sealing the coupling system in a hard disk. The simple, stable, portable, controlled, and integratable device would provide great potential in optical filters, sensors, nonlinear optics, cavity quantum electrodynamics, and especially some applications that require large resonators such as gyroscopes.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.U2441202,12372043,and 12372022)the Fundamental Research Funds for Central Universities。
文摘To break the limitations of the multi-dimensional(M-D)vibration isolation(VI)platforms with the Stewart-Gough design,such as strongly coupling motions,excessive friction in connections,heavy weight,and limited workspace,this study processes a novel platform integrated by a stiffness-adjustable origami spring sub-structure and a parallel mechanism.The origami-based stiffness-adjustable spring realizes low-frequency VI,and the parallel mechanism symmetry design realizes motions decoupling.In the origami-based sub-leg,the parallel-stack-assembly(PSA)design mechanism with two Miura origami configurations is proposed to generate a symmetrical negative stiffness property.Paired with a linear positive stiffness spring,the origami-based sub-leg has wide-amplitude-high-static-low-dynamic stiffness(WA-HSLDS)characteristics in one direction.Then,with construction of the parallel mechanism connected with origami-based sub-legs,an M-D VI platform is achieved,whose motions in the vertical direction and yaw direction are decoupled with the motions in the other directions.Based on the dynamic model and incremental harmonic balance(IHB)with the arc-length continuation method,appropriate structural parameters in the parallel mechanism part are figured out,and the accurate transmissibility in different directions is defined,which gives the parametric influencing investigations for realization of low-frequency VI performances.Finally,experiments are conducted to validate the accuracy and feasibility of the theoretical methods,and to demonstrate the performance of M-D low-frequency isolation with load-carrying capacity of the proposed VI platform.The integration of the origami into the parallel mechanism results in a compact,efficient,and flexible platform with nonlinear adjustability,offering new possibilities for lightweight M-D VI,and developing the practical applications in high-precision platforms in ocean and aerospace environments.
文摘Objective This study aimed to investigate the expression and clinical significance of serum lipoprotein(a) [LP(a)] in patients with gastric cancer. Methods Two hundred and twenty-two patients with gastric cancer(gastric cancer group) were selected from 2015 to 2017 [mean age(58.40 ± 10.40) years], as were 101 healthy persons [normal age group, mean age(58.18 ± 11.42) years]. Fasting blood samples were collected and evaluated by immunoturbidimetry with a biochemical analyzer. LP(a) concentration was observed and its difference was compared. Results There was no significant correlation between LP(a) and tumor stage(P > 0.05). Compared with the control group, the level of LP(a) in the male gastric cancer group was significantly higher than that in the control group(P < 0.05). In the subgroup analysis, the level of LP(a) and abnormal rate showed an increasing trend among patients with stages I–IV gastric cancer. The level of LP(a) in poorly differentiated gastric cancer patients was higher than that in the high middle differentiation group(P < 0.05). There was no significant difference in LP(a) levels among patients with different pathological types of gastric cancer(P > 0.05). Conclusion LP(a) was correlated with the occurrence, development and differentiation of gastric cancer, but not with the pathological classification of gastric cancer. Serum LP(a) concentration may be used as an indicator for the staging and prognosis of gastric cancer, but the specific underlying mechanism remains to be further studied.
基金supported by the National Natural Science Foundation of China (Nos. 61775209, 61801129, 41871229, and 61275011)
文摘In this Letter, we demonstrate high-quality(Q), millimeter-size, and V-shaped calcium fluoride crystalline resonators for modal modification. To manufacture such resonators, we develop a home-made machining system and explore a detailed process. With a dedicated polished container, three special polishing steps, including grinding, smoothing, and polishing, are employed to achieve the required surface smoothness, which is characterized by less than 3 nm. An ultra-high-Q factor exceeding 108 is obtained by a coupled tapered fiber.In addition, a customized packaged structure for our disk resonator is achieved. The Q maintenance and stable spectrum are realized by sealing the coupling system in a hard disk. The simple, stable, portable, controlled, and integratable device would provide great potential in optical filters, sensors, nonlinear optics, cavity quantum electrodynamics, and especially some applications that require large resonators such as gyroscopes.
