scholarly journals Multilayered Artificial Dura-Mater Models for a Minimally Invasive Brain Surgery Simulator

2020 ◽  
Vol 10 (24) ◽  
pp. 9000
Author(s):  
Masaru Takeuchi ◽  
Shusaku Hayakawa ◽  
Akihiko Ichikawa ◽  
Akiyuki Hasegawa ◽  
Yasuhisa Hasegawa ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Minimally Invasive ◽  
Dura Mater ◽  
Mechanical Characteristics ◽  
Pituitary Surgery ◽  
Multilayered Structure ◽  
Brain Surgery ◽  
Rubber Material ◽  
Fiber Sheet ◽  
Surgery Simulator

In this study, new artificial dura-mater models were developed using a multilayered structure of a rubber material (represent an elastic component of a dura-mater) and a fiber sheet (represent fiber component of a dura-mater). The artificial dura-mater models were prepared for use in a brain surgery simulator, especially for transnasal pituitary surgery. The mechanical characteristics of the artificial dura-mater models were tested to check the similarities with porcine dura-mater. Tensile stress, viscoelasticity, and the cutting force generated by microscissors were tested to evaluate the fabricated models. Neurosurgeons also assessed the dura-mater models to evaluate their characteristics. The results indicate that these models made of two different non-woven fiber sheets emulated accurately the actual dura-mater.

Analysis of the Crack Fracture Morphology of the Asphalt Mixture under Tensile Stress Effects

2011 ◽  
Vol 250-253 ◽  
pp. 3533-3537 ◽  
Author(s):  
Li Hua Zhao ◽  
Jing Yun Chen ◽  
Sheng Wu Wang
Keyword(s):  
Brittle Fracture ◽  
Fracture Surface ◽  
Tensile Stress ◽  
Mechanical Characteristics ◽  
Asphalt Mixture ◽  
Fracture Morphology ◽  
Microscopic Mechanism ◽  
Interface Zone ◽  
Stress Effects ◽  
Bending Fracture

Through studying the bending fracture and cleavage fracture of the asphalt mixture within the different temperature condition, confirming that the temperature influences the microscopic mechanism of mixture cracking: the fracture is relatively flat with low temperture, the destruction of the asphalt mixture is also mainly result of the brittle fracture; As the temperature rise, fracture surface becomes coarse, some part show large plastic elapse deformation. Adding fiber can reduce thickness of the asphalt membrane, improve the bonding strength of asphalt mastic, and greatly increase the ratio of the aggregate fracture and interface zone fracture, so as to enhance the asphalt mixture crack-resistance. The fracture morphology of asphalt mixture has a better reflection for its mechanical characteristics.

PREDICTORS AND INCIDENCE OF CENTRAL DIABETES INSIPIDUS AFTER ENDOSCOPIC PITUITARY SURGERY

Neurosurgery ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Dimitri G. Sigounas ◽  
Julie L. Sharpless ◽  
D. Ming L. Cheng ◽  
Tiffany G. Johnson ◽  
Brent A. Senior ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Diabetes Insipidus ◽  
Serum Sodium ◽  
Elevated Serum ◽  
High Sensitivity ◽  
Cerebrospinal Fluid Leak ◽  
Pituitary Surgery ◽  
Minimal Risk ◽  
Low Incidence ◽  
Traditional Approaches

Abstract OBJECTIVE With the advent of minimally invasive endoscopic pituitary surgery, there has been concern that the technique may be associated with higher rates of complications such as diabetes insipidus (DI) than traditional approaches, particularly early in a center's experience. We report the incidence and predictors of diabetes insipidus in patients after endoscopic transnasal resection (minimally invasive pituitary surgery) of pituitary lesions. METHODS Data were collected from hospital and clinic records on the first 119 consecutive patients undergoing endoscopic pituitary surgery at our center. RESULTS The rate of postoperative diabetes insipidus is low in patients undergoing minimally invasive pituitary surgery (permanent, 2.7%; transient, 13.6%). Factors associated with development of DI after minimally invasive pituitary surgery include Rathke's cleft cyst histology, intraoperative cerebrospinal fluid leak, and previous nonendoscopic lesion resection. Elevated serum sodium (>145 mmol/L) within the first 5 days postoperatively has a high sensitivity (87.5%), specificity (83.5%), and negative predictive value (99.5%) for permanent postoperative DI development. CONCLUSION Transitioning from microscopic to endoscopic pituitary surgery can be achieved with a low incidence of DI. An elevated serum sodium level in the first 5 postoperative days using standard monitoring can predict the chance of developing permanent DI. Patients having no elevated serum sodium measurements, defined as >145 mmol/L, in the first 5 days postoperatively will rarely, if ever, develop permanent DI, thereby validating short postoperative inpatient stays with minimal risk of readmission for DI management. Those with a single serum sodium measurement greater than 145 mmol/L have a 15% risk of developing permanent DI.

A Brain Surgery Simulator

2014 ◽  
Vol 34 (3) ◽  
pp. 12-18 ◽  
Author(s):  
Goretti Echegaray ◽  
Imanol Herrera ◽  
Iker Aguinaga ◽  
Carlos Buchart ◽  
Diego Borro
Keyword(s):  
Brain Surgery ◽  
Surgery Simulator

Minimally invasive pituitary surgery

2006 ◽  
Vol 17 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Marc K. Bassim ◽  
Brent A. Senior
Keyword(s):  
Minimally Invasive ◽  
Pituitary Surgery

Structural Optimization of Reinforced Concrete Aqueduct with Multi-Longitudinal Beams Part I: Method

2011 ◽  
Vol 243-249 ◽  
pp. 335-338
Author(s):  
Jun Feng Guan ◽  
Xiao Ke Li ◽  
Shun Bo Zhao
Keyword(s):  
Reinforced Concrete ◽  
Tensile Stress ◽  
Crack Width ◽  
Mechanical Characteristics ◽  
Shell Element ◽  
Element Model ◽  
Optimization Method ◽  
Internal Force ◽  
Structural Deformation ◽  
Maximum Crack

Former approaches fordesigning reinforced concrete aqueduct with multi-longitudinal beams were mostly based on experience. In this study, an optimization method is proposed instead. According to the mechanical characteristics of aqueduct, optimization principlesfor structural deformation coordination and sectional crack-resisting are developed. Furthermore, in optimization of large and complex reinforced concrete aqueduct, this method employs nominal tensile stress to control the maximum crack width. In addition, a 3D beam-shell element model is suggested for calculating internal force of aqueduct.

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