scholarly journals Comparison of Riboflavin/Ultraviolet-A Cross-Linking in Porcine, Rabbit, and Human Sclera

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Yali Zhang ◽  
Zhiwei Li ◽  
Lei Liu ◽  
Xuguang Han ◽  
Xiaomin Zhao ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Biomechanical Testing ◽  
Biomechanical Properties ◽  
Ultimate Stress ◽  
Cross Linking ◽  
Ultraviolet A ◽  
Rabbit Eye ◽  
Before And After ◽  
Biomechanical Parameters

Purpose. To compare the biomechanical properties of porcine, rabbit, and human sclera before and after riboflavin/ultraviolet-A (UVA) collagen cross-linking (CXL).Methods. Eight rabbits, 8 porcine eyeballs, and 8 human eyeballs were included. One rabbit eye and half of each bisected human and porcine eyeball were treated with riboflavin/UVA CXL. Untreated fellow rabbit eyes and eyeball halves served as controls. A 10 mm × 20 mm scleral band was harvested from each specimen. From this band, two 3.5 mm × 15.0 mm strips were prepared for biomechanical testing. The biomechanical parameters were ultimate stress, stress and Young’s modulus.Results. Values of stress, and Young’s modulus showed that human sclera was 4 times stiffer than porcine sclera and 3 times stiffer than rabbit sclera. In rabbit sclera, both the stress and Young’s modulus were significantly increased by CXL (P<0.05). In porcine sclera, only the ultimate stress was significantly increased by CXL (P<0.05). The biomechanical properties of human sclera were not statistically affected by CXL (P>0.05).Conclusions. Human sclera has higher biomechanical stiffness than porcine and rabbit sclera. With the same irradiation dose, riboflavin/UVA CXL increases the biomechanical stiffness of rabbit sclera but not porcine or human sclera.

scholarly journals Role of Corneal Epithelium in Riboflavin/Ultraviolet-A Mediated Corneal Cross-Linking Treatment in Rabbit Eyes

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Xiangchen Tao ◽  
Haiqun Yu ◽  
Yong Zhang ◽  
Zhiwei Li ◽  
Vishal Jhanji ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Corneal Epithelium ◽  
Young's Modulus ◽  
Biomechanical Properties ◽  
Cross Linking ◽  
Control Group ◽  
Ultraviolet A ◽  
Uva Irradiation ◽  
Maximal Stress

Purpose. To evaluate the role of corneal epithelium in riboflavin/ultraviolet-A (UVA) mediated corneal collagen cross-linking treatment.Methods. Fifty New Zealand rabbits were divided into 5 groups: UVA treatment with or without corneal epithelium, UVA+riboflavin treatment with or without corneal epithelium, and control without any treatment. All rabbits were sacrificed after irradiation and subsequently 4 mm × 10 mm corneal strips were harvested for biomechanical evaluation.Results. UVA irradiation alone did not enhance the maximal stress and Young’s modulus of corneal specimens with (3.15 ± 0.56 mpa, 1.00 ± 0.09 mpa) or without (3.53 ± 0.85 mpa, 0.94 ± 0.21 mpa) the corneal epithelium, compared to specimens in the control group (4.30 ± 0.68 mpa, 1.03 ± 0.24 mpa). However, UVA irradiation combined with riboflavin significantly increased the maximal stress and Young’s modulus of corneal specimens with (5.27 ± 1.09 mpa, 1.23 ± 0.23 mpa,P<0.05) or without (7.16 ± 1.88 mpa, 1.42 ± 0.16 mpa,P<0.05) corneal epithelium when compared to the control group. The maximal stress and Young’s modulus of cornea in UVA+riboflavin and “epithelium-off” group were 35.9% and 15.4% higher compared to the UVA+riboflavin and “epithelium-on” group, respectively (P<0.05).Conclusions. Our study shows that UVA+riboflavin treatment significantly affects the biomechanical properties of the cornea with and without epithelial removal. However, corneas without epithelium seem to benefit more compared to corneas with the epithelium.

Evaluation of Young’s Modulus in Achilles Tendons with Diabetic Neuroarthropathy

2005 ◽  
Vol 95 (3) ◽  
pp. 242-246 ◽  
Author(s):  
William P. Grant ◽  
Eric J. Foreman ◽  
Anne S. Wilson ◽  
Dwayne A. Jacobus ◽  
Renee M. Kukla
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Biomechanical Testing ◽  
Biomechanical Properties ◽  
Normal Tendon ◽  
Significant Difference ◽  
New Finding ◽  
Tendo Achillis

The Achilles tendon of the patient with Charcot’s foot neuroarthropathy has significantly altered physical properties compared with a normal tendon. Twenty-nine Achilles tendons from patients with Charcot’s foot (n = 20) and non-Charcot’s foot controls (n = 9) were loaded onto a biomechanical testing instrument. The biomechanical properties of the Charcot and control tendons were determined and the tendons were evaluated for differences in ultimate tensile strength and elasticity (Young’s modulus). Biomechanical test data show that there is a significant difference in ultimate tensile strength and elasticity between tendons of patients with Charcot’s foot and those of non-Charcot’s controls. The term diabetic tendo Achillis equinus is introduced as a new finding in diabetic neuroarthropathy. (J Am Podiatr Med Assoc 95(3): 242–246, 2005)

scholarly journals Root Traits and Biomechanical Properties of Three Tropical Pioneer Tree Species for Forest Restoration in Landslide Areas

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 179 ◽  
Author(s):  
Lee ◽  
Chu ◽  
Lin ◽  
Kung ◽  
Lin ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Young’S Modulus ◽  
Tree Species ◽  
Young's Modulus ◽  
Root Traits ◽  
Biomechanical Properties ◽  
Pioneer Species ◽  
Root Tensile Strength ◽  
Pioneer Tree ◽  
Macaranga Tanarius

Frequent earthquakes, monsoon torrential rains and typhoons cause severe landslides and soil erosion in Taiwan. Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus are major pioneer tree species appearing on landslide-scarred areas. Thus, these species can be used to restore the self-sustaining native vegetation on forest landslides, to control erosion, and to stabilize slope. However, their growth performance, root traits and biomechanical properties have not been well characterized. In this study, root system and root traits were investigated using the excavation method, and biomechanical tests were performed to determine the uprooting resistance, root tensile strength and Young’s modulus of 1-year-old Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus seedlings. The results reveal that relative to H. taiwanensis, M. tanarius and M. paniculatus seedlings had significantly larger root collar diameter, longer taproot length, higher root biomass, higher root density, higher root length density, heavier root mass, larger external root surface area, higher root tissue density, larger root volume, longer total root length, and a higher root tip number. Additionally, the height of M. paniculatus seedlings was significantly higher than those of H. taiwanensis and M. tanarius. Furthermore, the uprooting resistance and root tensile strength of M. paniculatus seedlings was significantly higher than those of H. taiwanensis and M. tanarius. Young’s modulus of M. paniculatus and M. tanarius seedlings was also significantly higher than that of H. taiwanensis. These growth characteristics and biomechanical properties demonstrate M. paniculatus and M. tanarius are superior than H. taiwanensis, considering growth performance, root anchorage capability, tensile strength and Young’s modulus. Taken as a whole, the rank order for species selection of these pioneer species for reforestation comes as: M. paniculatus M. tanarius H. taiwanensis. These results, along with knowledge on vegetation dynamics following landslides, allow us to better evaluate the effect of selective removal management of pioneer species on the resilience and sustainability of landslides.

scholarly journals Comparative investigations of in vitro and in vivo bioactivity of titanium vs. Ti–24Nb–4Zr–8Sn alloy before and after sandblasting and acid etching

RSC Advances ◽  
2020 ◽  
Vol 10 (40) ◽  
pp. 23582-23591
Author(s):  
Xin Liu ◽  
Yumei Niu ◽  
Weili Xie ◽  
Daqing Wei ◽  
Qing Du
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Stress Shielding ◽  
Acid Etching ◽  
Implant Material ◽  
Before And After ◽  
New Type

To avoid the failure of clinical surgery due to “stress shielding” and the loosening of an implant, a new type of alloy, Ti–24Nb–4Zr–8Sn (TNZS), with a low Young's modulus acted as a new implant material in this work.

scholarly journals Sago Starch-Mixed Low-Density Polyethylene Biodegradable Polymer: Synthesis and Characterization

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Md Enamul Hoque ◽  
Tan Jie Ye ◽  
Leng Chuan Yong ◽  
KhairulZaman Mohd Dahlan
Keyword(s):  
Mechanical Property ◽  
Young’S Modulus ◽  
Biodegradable Polymer ◽  
Young's Modulus ◽  
Starch Content ◽  
Synthesis And Characterization ◽  
Cross Linking ◽  
Content Increase ◽  
Sago Starch ◽  
Elongation At Break

This research focuses on synthesis and characterization of sago starch-mixed LDPE biodegradable polymer. Firstly, the effect of variation of starch content on mechanical property (elongation at break and Young’s modulus) and biodegradability of the polymer was studied. The LDPE was combined with 10%, 30%, 50%, and 70% of sago for this study. Then how the cross-linking with trimethylolpropane triacrylate (TMPTA) and electron beam (EB) irradiation influence the mechanical and thermal properties of the polymer was investigated. In the 2nd study, to avoid overwhelming of data LDPE polymer was incorporated with only 50% of starch. The starch content had direct influence on mechanical property and biodegradability of the polymer. The elongation at break decreased with increase of starch content, while Young’s modulus and mass loss (i.e., degradation) were found to increase with increase of starch content. Increase of cross-linker (TMPTA) and EB doses also resulted in increased Young’s modulus of the polymer. However, both cross-linking and EB irradiation processes rendered lowering of polymer’s melting temperature. In conclusion, starch content and modification processes play significant roles in controlling mechanical, thermal, and degradation properties of the starch-mixed LDPE synthetic polymer, thus providing the opportunity to modulate the polymer properties for tailored applications.

scholarly journals Synthesis, Characterization, and Modeling of Nanotube Materials with Variable Stiffness Tethers

2004 ◽  
Vol 851 ◽  
Author(s):  
S. J. V. Frankland ◽  
M. N. Herzog ◽  
G. M. Odegard ◽  
T. S. Gates ◽  
C. C. Fay
Keyword(s):  
Carbon Nanotube ◽  
Young’S Modulus ◽  
Mechanical Testing ◽  
Storage Modulus ◽  
Young's Modulus ◽  
Base Material ◽  
Variable Stiffness ◽  
Cross Linking ◽  
The Cross

ABSTRACTSynthesis, mechanical testing, and modeling have been performed for a carbon nanotube material in which the nanotubes are functionalized with variable stiffness tethers (VST) capable of cross-linking the nanotubes. Tests using nanoindentation indicated a six-fold enhancement in the storage modulus when comparing the base material (the cross-linking agent with no nanotubes) to the composite (functionalized nanotube material) that contained 5.3 wt% of nanotubes. To understand how crosslinking the nanotubes may further alter the stiffness, a model of the system was constructed using nanotubes crosslinked with the VST. The model predicted that for a composite with 5 wt% nanotubes at random orientations, crosslinked with the VST, the bulk Young's modulus was reduced to 30% that of the non-crosslinked equivalent.

scholarly journals Correlations of Geometry and Infill Degree of Extrusion Additively Manufactured 316L Stainless Steel Components

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5173
Author(s):  
Tobias Rosnitschek ◽  
Andressa Seefeldt ◽  
Bettina Alber-Laukant ◽  
Thomas Neumeyer ◽  
Volker Altstädt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Product Development ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Dimensional Accuracy ◽  
Product Development Process ◽  
Stainless Steel 316L ◽  
Before And After ◽  
Metal Extrusion

This study focuses on the effect of part geometry and infill degrees on effective mechanical properties of extrusion additively manufactured stainless steel 316L parts produced with BASF’s Ultrafuse 316LX filament. Knowledge about correlations between infill degrees, mechanical properties and dimensional deviations are essential to enhance the part performance and further establish efficient methods for the product development for lightweight metal engineering applications. To investigate the effective Young’s modulus, yield strength and bending stress, standard testing methods for tensile testing and bending testing were used. For evaluating the dimensional accuracy, the tensile and bending specimens were measured before and after sintering to analyze anisotropic shrinkage effects and dimensional deviations linked to the infill structure. The results showed that dimensions larger than 10 mm have minor geometrical deviations and that the effective Young’s modulus varied in the range of 176%. These findings provide a more profound understanding of the process and its capabilities and enhance the product development process for metal extrusion-based additive manufacturing.

scholarly journals On-chip pressure measurements and channel deformation after oil absorption

2020 ◽  
Vol 2 (9) ◽  
Author(s):  
Liam Hunter ◽  
Julia Gala de Pablo ◽  
Ashley C. Stammers ◽  
Neil H. Thomson ◽  
Stephen D. Evans ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Flow Rate ◽  
Young's Modulus ◽  
Pressure Profile ◽  
Mineral Oil ◽  
Microfluidic Channels ◽  
Oil Absorption ◽  
Channel Deformation ◽  
Before And After ◽  
On Chip

Abstract Microfluidic channels moulded from the soft polymer poly(dimethylsiloxane) (PDMS) are widely used as a platform for mimicking biological environments, and can be used for the simulation of fluid filled structures such as blood and lung vessels. The control of pressure and flow rate within these structures is vital to mimic physiological conditions. The flexibility of PDMS leads to pressure-induced deformation under flow, leading to variable flow profiles along a device. Here, we investigate the change in Young’s modulus of microfluidic channels due to infiltration of mineral oil, a PDMS permeable fluid, and how this affects the resulting pressure profile using a novel pressure measurement method. We found a 53% decrease in Young’s modulus of PDMS due to mineral oil absorption over the course of 3 h accounted for lower internal pressure and larger channel deformation compared to fresh PDMS at a given flow rate. Confocal fluorescence microscopy used to image channel profiles before and after the introduction of mineral oil showed a change in pressure-induced deformation after infiltration of the oil. Atomic force microscopy (AFM) nanoindentation was used to measure Young’s modulus of PDMS before ($$2.80 \pm 0.03$$ 2.80 ± 0.03 MPa) and after ($$1.32 \pm 0.04$$ 1.32 ± 0.04 MPa) mineral oil absorption. Raman spectroscopy showed the infiltration of mineral oil into PDMS from channel walls and revealed the diffusion coefficient of mineral oil in PDMS.

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