An examination of alternative explanations of split-line orientation in compact bone

To enhance the mechanical strength and bioactivity of poly(lactic acid) (PLA) to the level that can be used as a material for spinal implants, poly(glycolic acid) (PGA) fibers and hydroxyapatite (HA) were introduced as fillers to PLA composites. To improve the poor interface between HA and PLA, HA was grafted by PLA to form HA-g-PLA through coupling reactions, and mixed with PLA. The size of the HA particles in the PLA matrix was observed to be reduced from several micrometers to sub-micrometer by grafting PLA onto HA. The tensile and flexural strength of PLA/HA-g-PLA composites were increased compared with those of PLA/HA, apparently due to the better dispersion of HA and stronger interfacial adhesion between the HA and PLA matrix. We also examined the effects of the length and frequency of grafted PLA chains on the tensile strength of the composites. By the addition of unidirectionally aligned PGA fibers, the flexural strength of the composites was greatly improved to a level comparable with human compact bone. In the bioactivity tests, the growth of apatite on the surface was fastest and most uniform in the PLA/PGA fiber/HA-g-PLA composite.

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Measuring the stopping power of α particles in compact bone for BNCT

Journal of Physics Conference Series ◽

10.1088/1742-6596/583/1/012047 ◽

2015 ◽

Vol 583 ◽

pp. 012047 ◽

Cited By ~ 2

Author(s):

L Provenzano ◽

L M Rodríguez ◽

D Fregenal ◽

G Bernardi ◽

C Olivares ◽

...

Keyword(s):

Compact Bone ◽

Stopping Power ◽

Α Particles

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β-Hydroxy-β-Methylbutyrate (HMB) Supplementation Prevents Bone Loss during Pregnancy—Novel Evidence from a Spiny Mouse (Acomys cahirinus) Model

International Journal of Molecular Sciences ◽

10.3390/ijms22063047 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3047

Author(s):

Ewa Tomaszewska ◽

Janine Donaldson ◽

Jakub Kosiński ◽

Piotr Dobrowolski ◽

Agnieszka Tomczyk-Warunek ◽

...

Keyword(s):

Articular Cartilage ◽

Bone Loss ◽

Young Modulus ◽

Compact Bone ◽

Second Trimester ◽

Mineral Density ◽

Tissue Quality ◽

Cross Sectional ◽

Acomys Cahirinus ◽

Trabecular Number

The aim of this study was to determine the effects of ß-hydroxy-ß-methylbutyrate (HMB) supplementation during pregnancy on postpartum bone tissue quality by assessing changes in trabecular and compact bone as well as in hyaline and epiphyseal cartilage. The experiment was carried out on adult 6-month-old female spiny mice (Acomys cahirinus) divided into three groups: pregnant control (PregCont), pregnant HMB-treated (supplemented with 0.02 g/kg b.w of HMB during the second trimester of pregnancy, PregHMB), and non-pregnant females (NonPreg). Cross-sectional area and cortical index of the femoral mid-shaft, stiffness, and Young modulus were significantly greater in the PregHMB group. Whole-bone mineral density was similar in all groups, and HMB supplementation increased trabecular number. Growth plate cartilage was the thinnest, while the articular cartilage was the thickest in the PregHMB group. HMB supplementation increased the content of proteoglycans in the articular cartilage and the percentage of immature collagen content in metaphyseal trabeculae and compact bone. In summary, dietary HMB supplementation during the second trimester of pregnancy intensifies bone metabolic processes and prevents bone loss during pregnancy.

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Surgical Drilling: Design and Performance of an Improved Drill

Journal of Biomechanical Engineering ◽

10.1115/1.3138356 ◽

1982 ◽

Vol 104 (3) ◽

pp. 245-252 ◽

Cited By ~ 79

Author(s):

S. Saha ◽

S. Pal ◽

J. A. Albright

Keyword(s):

Compact Bone ◽

Helix Angle ◽

Rake Angle ◽

Peak Temperature ◽

Published Data ◽

Drill Bit ◽

Effective Removal ◽

Split Point ◽

And Performance ◽

Twist Drills

The majority of twist drills used in orthopaedics are very similar to chisel pointed metal drilling bits. Modifications usually observed are reduction of the point angle to 90 deg and sometimes grinding of the entire cutting lip at 0 deg rake angle, which appeared to have been made arbitrarily without any advantage. We have attempted to design a surgical drill bit with the objective of minimization of the drilling thrust and temperature and effective removal of bone chips. Our results showed that the presence of the chisel edge was mainly responsible for increasing the thrust force and the temperature developed. The effects of a constant feed rate and thrust on the peak temperature were also examined. The combined effect of the helix and the point angles on the rake angle which in turn determines the cutting efficiency was analyzed for various types of surgical bits. Based on our results and previously published data from the literature an optimized drill bit was designed with a split point, a point angle of 118 deg, a parabolic flute, and a helix angle of 36 deg and its performance was compared with other existing surgical drill bits. For drilling in compact bone, the new design decreased the thrust load by 45 percent and the peak temperature rise by 41 percent. Simlar improvements were also recorded for drilling bone cement. The time of drilling a bone cortex was also significantly reduced and “walking” on the curved bone surface was eliminated and dimensional tolerance on hole sizes was improved. The new design is likely to reduce the time of surgery and also minimize the tissue damage.

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Response dependency and processing dependency of line orientation and position in a single-item task

Psychological Research ◽

10.1007/bf00447086 ◽

1995 ◽

Vol 58 (1) ◽

pp. 19-30 ◽

Cited By ~ 4

Author(s):

A. H. C. van der Heijden ◽

G. Wolters ◽

R. F. T. Brouwer

Keyword(s):

Line Orientation ◽

Single Item

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