AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic...AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic cancer patients had their first EUS-FNA between February 2001 and December 2017. Among them, 201 who underwent EUS-FNA for pancreatic head lesions were included in this study. EUS-FNA was performed by the push method in 85 patients, the pull method in 101 patients and both the push and pull methods in 15 patients. After propensity score matching(age, sex, tumor diameter, and FNA needle), 85 patients each were stratified into the push and pull groups. Patient characteristics and EUSFNA-related factors were compared between the two groups.RESULTS Patient characteristics were not significantly different between the two groups. The distance to lesion was significantly longer in the push group than in the pull group(13.9 ± 4.9 mm vs 7.0 ± 4.9 mm, P < 0.01). The push method was a significant factor influencing the distance to lesion(≥ median 10 mm)(P < 0.01). Additionally, tumor diameter ≥ 25 mm(OR = 1.91, 95%CI: 1.02-3.58, P = 0.043) and the push method(OR = 1.91, 95%CI: 1.03-3.55, P = 0.04) were significant factors contributing to the histological diagnosis of malignancy.CONCLUSION The pull method shortened the distance between the endoscope and the lesion and facilitated EUS-FNA of pancreatic head cancer. The push method contributed to the histological diagnosis of pancreatic head cancer using EUS-FNA specimens.展开更多
The reaction of earth to pull-out process of frictional rock bolts was here modeled by the distinct element method (DEM). Ten frictional bolts were prepared;the expanding shells of five bolts included convex edges and...The reaction of earth to pull-out process of frictional rock bolts was here modeled by the distinct element method (DEM). Ten frictional bolts were prepared;the expanding shells of five bolts included convex edges and the others had the shells with concave bits. The strength of bolts was measured by applying a standard pull-out test;the results confirmed that the strength of shells with convex edges was remarkably more than the strength of other shells. Furthermore, a two-dimensional DEM model of the test was developed by a particle flow code;the obtained results showed that the reaction of rock particles to the contacts occurring between the convex edges and earth was considerably more than those of the concave bits. In the other words, the convex edges transferred the pull-out force into a large area of the surrounded rock, causing these bolts to have the highest resistance against earth movements.展开更多
This paper provides the static and dynamic pullin behavior of nano-beams resting on the elastic foundation based on the nonlocal theory which is able to capture the size effects for structures in micron and sub-micron...This paper provides the static and dynamic pullin behavior of nano-beams resting on the elastic foundation based on the nonlocal theory which is able to capture the size effects for structures in micron and sub-micron scales. For this purpose, the governing equation of motion and the boundary conditions are driven using a variational approach. This formulation includes the influences of fringing field and intermolecular forces such as Casimir and van der Waals forces. The differential quadrature （DQ） method is employed as a high-order approximation to discretize the governing nonlinear differential equation, yielding more accurate results with a Considerably smaller number of grid points. In addition, a powerful analytical method called parameter expansion method （PEM） is utilized to compute the dynamic solution and frequency-amplitude relationship. It is illustrated that the first two terms in series expansions are sufficient to produce an acceptable solution of the mentioned structure. Finally, the effects of basic parameters on static and dynamic pull-in insta- bility and natural frequency are studied.展开更多
A trial solution for bending deflection of a multilayered micro-bridge subject to a voltage induced load is presented. The relation between the applied voltage and the displacements of the micro-bridge in the pull-in ...A trial solution for bending deflection of a multilayered micro-bridge subject to a voltage induced load is presented. The relation between the applied voltage and the displacements of the micro-bridge in the pull-in state is analyzed by energy method. Furthermore, two analytical expressions about normalized displacement and pull-in voltage are carried out. It’s proved that the value of normalized displacement is not influenced by residual stress if axial and shear deformation is ignored. Finally, the theoretical results are compared with that of FEM, and they show good agreement.展开更多
采用微下拉法制备了不同浓度Nd^(3+)掺杂的Sr 0.7 La 0.3 Mg 0.3 Al 11.7 O 19(Nd∶ASL)单晶光纤,并对其晶体结构、偏振光谱和连续激光性能进行了研究。计算得到Nd∶ASL单晶光纤的光谱参数Ω2、Ω4和Ω6分别为1.09310^(-20)、2.28510^(-...采用微下拉法制备了不同浓度Nd^(3+)掺杂的Sr 0.7 La 0.3 Mg 0.3 Al 11.7 O 19(Nd∶ASL)单晶光纤,并对其晶体结构、偏振光谱和连续激光性能进行了研究。计算得到Nd∶ASL单晶光纤的光谱参数Ω2、Ω4和Ω6分别为1.09310^(-20)、2.28510^(-20)和2.11710^(-20)cm^(2)。0.5%、1.0%、3.0%和5.0%Nd∶ASL单晶光纤^(4)F_(3/2)能级的荧光寿命分别为375、398、384和363μs。采用发射波长800 nm的激光二极管泵浦3.0%Nd∶ASL(原子数分数)单晶光纤,在1055 nm处获得了1.08 W的连续激光输出,斜效率为18.5%。研究结果表明采用微下拉生长的Nd∶ASL单晶光纤是一种有潜力的激光增益介质。展开更多
文摘AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic cancer patients had their first EUS-FNA between February 2001 and December 2017. Among them, 201 who underwent EUS-FNA for pancreatic head lesions were included in this study. EUS-FNA was performed by the push method in 85 patients, the pull method in 101 patients and both the push and pull methods in 15 patients. After propensity score matching(age, sex, tumor diameter, and FNA needle), 85 patients each were stratified into the push and pull groups. Patient characteristics and EUSFNA-related factors were compared between the two groups.RESULTS Patient characteristics were not significantly different between the two groups. The distance to lesion was significantly longer in the push group than in the pull group(13.9 ± 4.9 mm vs 7.0 ± 4.9 mm, P < 0.01). The push method was a significant factor influencing the distance to lesion(≥ median 10 mm)(P < 0.01). Additionally, tumor diameter ≥ 25 mm(OR = 1.91, 95%CI: 1.02-3.58, P = 0.043) and the push method(OR = 1.91, 95%CI: 1.03-3.55, P = 0.04) were significant factors contributing to the histological diagnosis of malignancy.CONCLUSION The pull method shortened the distance between the endoscope and the lesion and facilitated EUS-FNA of pancreatic head cancer. The push method contributed to the histological diagnosis of pancreatic head cancer using EUS-FNA specimens.
文摘The reaction of earth to pull-out process of frictional rock bolts was here modeled by the distinct element method (DEM). Ten frictional bolts were prepared;the expanding shells of five bolts included convex edges and the others had the shells with concave bits. The strength of bolts was measured by applying a standard pull-out test;the results confirmed that the strength of shells with convex edges was remarkably more than the strength of other shells. Furthermore, a two-dimensional DEM model of the test was developed by a particle flow code;the obtained results showed that the reaction of rock particles to the contacts occurring between the convex edges and earth was considerably more than those of the concave bits. In the other words, the convex edges transferred the pull-out force into a large area of the surrounded rock, causing these bolts to have the highest resistance against earth movements.
文摘This paper provides the static and dynamic pullin behavior of nano-beams resting on the elastic foundation based on the nonlocal theory which is able to capture the size effects for structures in micron and sub-micron scales. For this purpose, the governing equation of motion and the boundary conditions are driven using a variational approach. This formulation includes the influences of fringing field and intermolecular forces such as Casimir and van der Waals forces. The differential quadrature （DQ） method is employed as a high-order approximation to discretize the governing nonlinear differential equation, yielding more accurate results with a Considerably smaller number of grid points. In addition, a powerful analytical method called parameter expansion method （PEM） is utilized to compute the dynamic solution and frequency-amplitude relationship. It is illustrated that the first two terms in series expansions are sufficient to produce an acceptable solution of the mentioned structure. Finally, the effects of basic parameters on static and dynamic pull-in insta- bility and natural frequency are studied.
文摘A trial solution for bending deflection of a multilayered micro-bridge subject to a voltage induced load is presented. The relation between the applied voltage and the displacements of the micro-bridge in the pull-in state is analyzed by energy method. Furthermore, two analytical expressions about normalized displacement and pull-in voltage are carried out. It’s proved that the value of normalized displacement is not influenced by residual stress if axial and shear deformation is ignored. Finally, the theoretical results are compared with that of FEM, and they show good agreement.
文摘采用微下拉法制备了不同浓度Nd^(3+)掺杂的Sr 0.7 La 0.3 Mg 0.3 Al 11.7 O 19(Nd∶ASL)单晶光纤,并对其晶体结构、偏振光谱和连续激光性能进行了研究。计算得到Nd∶ASL单晶光纤的光谱参数Ω2、Ω4和Ω6分别为1.09310^(-20)、2.28510^(-20)和2.11710^(-20)cm^(2)。0.5%、1.0%、3.0%和5.0%Nd∶ASL单晶光纤^(4)F_(3/2)能级的荧光寿命分别为375、398、384和363μs。采用发射波长800 nm的激光二极管泵浦3.0%Nd∶ASL(原子数分数)单晶光纤,在1055 nm处获得了1.08 W的连续激光输出,斜效率为18.5%。研究结果表明采用微下拉生长的Nd∶ASL单晶光纤是一种有潜力的激光增益介质。
