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.

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 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 Conjunctival Ultraviolet Autofluorescence as a Measure of Riboflavin and Ultraviolet and Accelerated Cross-Linking Exposure in Keratoconic Patients

2020 ◽  
Vol 9 (9) ◽  
pp. 2693
Author(s):  
Arleta Waszczykowska ◽  
Krzysztof Bartosiewicz ◽  
Michał Podgórski ◽  
Ewa Zmysłowska-Polakowska ◽  
Piotr Jurowski
Keyword(s):  
Anterior Segment ◽  
Cross Linking ◽  
Control Group ◽  
Study Group ◽  
Uva Irradiation ◽  
Lower Stage ◽  
Ocular Surface Diseases ◽  
Third Stage ◽  
Comparative Group ◽  
Patient Groups

Purpose: The study was performed to analyze the prevalence of the conjunctival ultraviolet autofluorescence (CUVAF) area in keratoconic eyes and changes caused by UVA-irradiation as a component of accelerated corneal cross-linking (aCXL). Methods: The study group involved 20 keratoconic patients subjected to aCXL surgery in one eye. The comparative group consisted of 111 age- and sex-matched patients with healthy corneas. The images of the anterior segment in both patient groups were taken using a Coroneo camera. In the study group the photos were taken before and immediately after the surgery, and 7 and 30 days following the procedure. Results: Nasal and temporal autofluorescence area (AN+T) were significantly smaller in a keratoconic patients group compared to control group (p = 0.0001). Patients with the third stage of keratoconus had significantly higher AN+T (p = 0.0277) compared with individuals with lower stage keratoconus. No statistically significant CUVAF changes were observed after the aCXL procedure. In keratoconic patients with primary CUVAF undergoing aCXL, a temporary fast enlargement of the autofluorescence area was observed. Conclusions: The eyes undergoing the aCXL procedure showed no difference in the size of the CUVAF area but such patients should be in strict follow-up in order to reveal UV-related ocular surface diseases.

scholarly journals Microtubules regulate cardiomyocyte transversal Young’s modulus

2020 ◽  
Vol 117 (6) ◽  
pp. 2764-2766 ◽  
Author(s):  
Pamela Swiatlowska ◽  
Jose L. Sanchez-Alonso ◽  
Peter T. Wright ◽  
Pavel Novak ◽  
Julia Gorelik
Keyword(s):  
Young’S Modulus ◽  
Mechanical Loading ◽  
Posttranslational Modifications ◽  
Young's Modulus ◽  
Cardiac Mechanics ◽  
Ion Conductance ◽  
Loading And Unloading ◽  
Microtubular Network ◽  
Significant Attention

The field of cardiomyocyte mechanobiology is gaining significant attention, due to accumulating evidence concerning the significant role of cellular mechanical effects on the integrated function of the heart. To date, the protein titin has been demonstrated as a major contributor to the cardiomyocytes Young’s modulus (YM). The microtubular network represents another potential regulator of cardiac mechanics. However, the contribution of microtubules (MTs) to the membrane YM is still understudied and has not been interrogated in the context of myocardial infarction (MI) or mechanical loading and unloading. Using nanoscale mechanoscanning ion conductance microscopy, we demonstrate that MTs contribute to cardiomyocyte transverse YM in healthy and pathological states with different mechanical loading. Specifically, we show that posttranslational modifications of MTs have differing effects on cardiomyocyte YM: Acetylation provides flexibility, whereas detyrosination imparts rigidity. Further studies demonstrate that there is no correlation between the total protein amount of acetylated and detyrosinated MT. Yet, in the polymerized-only populations, an increased level of acetylation results in a decline of detyrosinated MTs in an MI model.

scholarly journals Short-term angiotensin II treatment regulates cardiac nanomechanics via microtubule modifications

Nanoscale ◽  
2020 ◽  
Vol 12 (30) ◽  
pp. 16315-16329
Author(s):  
Pamela Swiatlowska ◽  
Jose L. Sanchez-Alonso ◽  
Catherine Mansfield ◽  
Denis Scaini ◽  
Yuri Korchev ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Short Term ◽  
Nanoscale Level

MechanoSICM is used to understand the role of angiotensin II on transverse Young's modulus at the nanoscale level.

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 Strength of Materials Teaching from Active Learning

2021 ◽  
Vol 4 (1) ◽  
pp. 42-62
Author(s):  
Luciano Andreatta-da-Costa
Keyword(s):  
Active Learning ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Hypothesis Test ◽  
Control Group ◽  
Pedagogical Intervention ◽  
Traditional Lecture ◽  
Hands On ◽  
Group Control Group ◽  
Conceptual Nature

This paper presents the results of research conducted in the area of engineering education based on active learning from a hands-on experiment determining the Young’s modulus of rubber bands. This research primarily aims to evaluate the extent to which active learning contributes to a better understanding of the Young’s modulus. The theoretical framework emphasises the need for student action in knowledge-building. A hypothesis test for proportions was used to compare the average scores obtained by students from two groups on a test given at the end of each pedagogical intervention. The first group (control group) took traditional lecture-based classes, and the second group took classes combined with a hands-on experiment using rubber bands. The results showed a significant improvement in the students who conducted the practical experiment for questions of a conceptual nature and a statistical difference between the performance for the conceptual questions and calculation questions in both groups.

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