The aim of this in vitro study was to determine the effect of fissure
types on the microleakage, and penetration ability of fissure sealant.
The occlusal surface of ninety caries-free extracted human upper
premolars were cleaned, etched and sealed
with (UltraSeal XT
Plus) Sealant. The sealed teeth were thermocycled then coated with
two layers of nail varnish, leaving exposed a 1 mm window around
the sealant margins and then immersed in 1% methylene blue for 24
hours. Each tooth was sectioned bucco-lingually and examined with
a stereo microscope (40x magnification) for fissure types,
microleakage, and penetration ability.
This paper makes an experimental and analytical investigation of cracks characteristics in Fiber Reinforced Polymer strengthened RC beams under different levels of sustained load and Reinforced ratio.
As the equations available for conventional RC b
eams are inappropriate for the calculation of the short-term crack width in FRP-strengthened RC beams[8], a statistical analysis is carried out on available test data from international sources [6-9-10] and from the test results obtained in the current study (Concrete Labor- Civil engineering Department- Damascus University-2014) to establish a new equation that considers the effect of the FRP laminates. This equation is a correlation of stress in steel bars, concrete surface tension , and effective side cover.
The long-term crack width is then related to the instantaneous crack width by empirical equations which are derived from the test results obtained in the current study.
The extended crack resistance of concrete is necessary in the desisn of nonlinear behavior of structural It can be described through the intensity stress factor and the critical crack opening under maximum
force. The length of the crack is necessary
for calculating intensity stress factor and the critical crack opening under maximum force.
The aim of this work is to conehede the relations between intensity stress factor and the critical crack opening under maximum force with the material properties of concrete such as paste volume, compressive strength and maximum aggregate diameter. The length of crack is calculated using the analytical model of Olesen that depends on bilinear softening, and the parameters of the softening curve were found using inverse analysis. The experimental results of three point bending test for beams with different sizes which are made from concretes with different compressive strengths are used in the inverse analysis.
It is found that intensity stress factor and the critical crack opening under maximum force depend on paste volume and they increase when F'c increases, while they are independent from maximum
aggregate size.
The purpose of this paper is to determine whether there is a difference in the postoperative corneal astigmatism and uncorrected visual acuity UCVA as well as best corrected visual acuity BCVA between 2 types of clear corneal incisions used in phacoe
mulsification: the superior and on the steepest clear corneal incision.
This study included 40 patients with cataract and mild to moderate corneal astigmatism (0.50 D - 2.00 D) who underwent phacoemulsification with foldable posterior chamber lens (with 3.2mm corneal incision). Patients were randomly divided into two groups: superior clear corneal incision group SCCI (20 eyes) and on the steepest clear corneal incision group OCCI (20 eyes). Measurements included corneal astigmatism by Keratometry, UCVA and BCVA. These Measurements were taken on first day,1 week, 2 weeks,1, 2,3 and 6 months. The mean preoperative corneal astigmatism was (1.24 D ± 0.44),(1.25 D ± 0.44) in superior corneal incision group, and on the steepest corneal incision group, respectively. After 6 months postoperatively, the mean corneal astigmatism was (1.53 D ± 0.49) in SCCI group, (1.03 D± 0.39) in OCCI group, with statistically significant difference (p<0.001).There was statistically significant difference in UCVA. But there was no statistically significant difference in BCVA.
The paper concludes that compared with SCCI, the OCCI could correct some corneal astigmatism
