The cross-sectional size and shape of human terminal scalp hair

1997 ◽  
Vol 136 (2) ◽  
pp. 159-165 ◽  
Author(s):  
P.E. HUTCHINSON ◽  
J.R. THOMPSON
Keyword(s):  
Scalp Hair ◽  
Cross Sectional ◽  
Size And Shape ◽  
Cross Sectional Size ◽  
The Cross

Design Innovation Size and Shape Optimization of a 1.0mm Multifunctional Forceps-Scissors Surgical Instrument

2008 ◽  
Vol 2 (1) ◽  
Author(s):  
Milton E. Aguirre ◽  
Mary Frecker
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shape Optimization ◽  
Optimization Problems ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Element Analysis ◽  
Cross Sectional ◽  
Size And Shape ◽  
The Cross

A size and shape optimization routine is developed for a 1.0mm diameter multifunctional instrument for minimally invasive surgery. The instrument is a compliant mechanism capable of both grasping and cutting. Multifunctional instruments are expected to be beneficial in the operating room because of their ability to perform multiple surgical tasks, thereby decreasing the total number of instrument exchanges in a single procedure. With fewer instrument exchanges, the risk of inadvertent tissue trauma as well as overall surgical time and costs are reduced. The focus of this paper is to investigate the performance effects of allowing the cross-sectional area along the length of the device to vary. This investigation is accomplished by defining various cross-sectional segments in terms of parametric variables and optimizing the dimensions of the instrument to provide a sufficient opening of the forceps jaws while maintaining adequate cutting and grasping forces. Two optimization problems are considered. First, all parametric segments are set equal to one another to achieve size optimization. Second, each segment is allowed to vary independently, thereby achieving shape optimization. Large deformation finite element analysis and optimization are conducted using ANSYS®. Finally, prototypes are fabricated using wire EMD and experiments are conducted to evaluate the instrument performance. As a result of allowing the cross-sectional area to vary, i.e., conducting shape optimization, the forceps and scissors blocked forces increased by as much as 83.2% and 87%, respectively. During prototype evaluations, it is found that the finite element analysis predictions were within 10% of the measured tool performance. Therefore, for this application, it is concluded that performing shape optimization does significantly influence the performance of the instrument.

On the cross-sectional shape of the cellulose crystallites in the tunicate Halocynthia papillosa

1990 ◽  
Vol 48 (3) ◽  
pp. 566-567
Author(s):  
J.-F. Revol ◽  
Y. Van Daele ◽  
F. Gaill
Keyword(s):  
Contrast Imaging ◽  
Animal Kingdom ◽  
Bright Field ◽  
Field Mode ◽  
Cross Sectional ◽  
Ultrathin Sections ◽  
The Cross ◽  
Sectional Shape ◽  
Valonia Ventricosa ◽  
C Nmr

The only form of cellulose which could unequivocally be ascribed to the animal kingdom is the tunicin that occurs in the tests of the tunicates. Recently, high-resolution solid-state l3C NMR revealed that tunicin belongs to the Iβ form of cellulose as opposed to the Iα form found in Valonia and bacterial celluloses. The high perfection of the tunicin crystallites led us to study its crosssectional shape and to compare it with the shape of those in Valonia ventricosa (V.v.), the goal being to relate the cross-section of cellulose crystallites with the two allomorphs Iα and Iβ.In the present work the source of tunicin was the test of the ascidian Halocvnthia papillosa (H.p.). Diffraction contrast imaging in the bright field mode was applied on ultrathin sections of the V.v. cell wall and H.p. test with cellulose crystallites perpendicular to the plane of the sections. The electron microscope, a Philips 400T, was operated at 120 kV in a low intensity beam condition.

Sign in / Sign up

Export Citation Format

Share Document