Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study

Eman Z. Al-Shehri,Afnan O. Al-Zain,Alaa H. Sabrah,Sarah S. Al-Angari,Laila Al Dehailan,George J. Eckert,Mutlu Özcan,Jeffrey A. Platt,Marco C. Bottino 대한치과보존학회 2017 Restorative Dentistry & Endodontics Vol.42 No.3

Objectives: To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al2O3) particles at different pressures. Materials and Methods: Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ2 tests (α = 0.05). Results: The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. Conclusions: CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.

Genotype and Allelic Frequencies of a Newly Identified Mutation Causing Blindness in Jordanian Awassi Sheep Flocks

Jawasreh, K.I.Z.,Ababneh, H.,Awawdeh, F.T.,Al-Massad, M.A.,Al-Majali, A.M. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.1

A total of 423 blood samples were collected (during 2009 and 2010) from all the ram holdings at three major Jordanian governmental Awassi breeding stations (Al-Khanasry, Al- Mushairfa and Al-Fjaje) and two private flocks. All blood samples were screened for the presence of mutations at the CNGA3 gene (responsible for day blindness in Awassi sheep) using RFLP-PCR. The day blindness mutation was detected in all studied flocks. The overall allele and genotype frequencies of all studied flocks of the day blindness mutation were 0.088 and 17.49%, respectively. The genotype and allele frequencies were higher in station flocks than the farmer flocks (0.121, 24.15 and 0.012, 2.32, respectively). Al-Mushairfa and Al-Khanasry stations have the highest genotype and allele frequencies for the day blindness mutation that were 27.77, 30.00% and 0.14, 0.171, respectively. The investigated farmer flocks have low percentages (0.03, 5.88% at Al-Shoubak and 0.005 and 1.05%, at Al-Karak, respectively for genotype and allele frequencies) compared with the breeding stations. Ram culling strategy was applied throughout the genotyping period in order to gradually eradicate this newly identified day blindness mutation from Jordanian Breeding station, since they annually distribute a high percentage of improved rams to farmer's flocks.

Measurement of Z⁰-boson production at large rapidities in Pb–Pb collisions at _{s NN} = 5.02 TeV

Acharya, S.,Adamová,, D.,Adolfsson, J.,Aggarwal, M.M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahn, S.U.,Aiola, S.,Akindinov, A.,Al-Turany, M.,Alam, S.N.,Albuquerque, D.S.D.,Aleks North-Holland Pub. Co 2018 Physics letters. Section B Vol.780 No.-

<P><B>Abstract</B></P> <P>The production of <SUP> Z 0 </SUP> bosons at large rapidities in Pb–Pb collisions at <SUB> s NN </SUB> = 5.02 TeV is reported. <SUP> Z 0 </SUP> candidates are reconstructed in the dimuon decay channel ( <SUP> Z 0 </SUP> → <SUP> μ + </SUP> <SUP> μ − </SUP> ), based on muons selected with pseudo-rapidity − 4.0 < η < − 2.5 and <SUB> p T </SUB> > 20 GeV/ c . The invariant yield and the nuclear modification factor, <SUB> R AA </SUB> , are presented as a function of rapidity and collision centrality. The value of <SUB> R AA </SUB> for the 0–20% central Pb–Pb collisions is 0.67 ± 0.11 (stat.) ± 0.03 (syst.) ± 0.06 (corr. syst.) , exhibiting a deviation of 2.6<I>σ</I> from unity. The results are well-described by calculations that include nuclear modifications of the parton distribution functions, while the predictions using vacuum PDFs deviate from data by 2.3<I>σ</I> in the 0–90% centrality class and by 3<I>σ</I> in the 0–20% central collisions.</P>

Staurosporine analogues from microbial and synthetic sources and their biological activities.

Park, B S,Abdel-Azeem, A Z,Al-Sanea, M M,Yoo, K H,Tae, J S,Lee, S H Bentham Science Publishers 2013 Current medicinal chemistry Vol.20 No.31

<P>In 1977 an unknown natural product was isolated from Streptomyces staurosporeus by Omura et al. during a search for new alkaloids present in actinomycetes and was given the name AM-2282. Later, the structure of AM-2282 was elucidated by single crystal X-ray analysis and renamed as staurosporine. It has been published that staurosporine and its analogues display strong inhibitory effect against a variety of kinases and a number of biological properties such as antifungal, antibacterial, and immunosuppressive activities. Despite strong inhibitory activity of staurosporine, a very high level of cross-reactivity makes it impossible to use staurosporine as a therapeutic agent. In the course of searching for other staurosporine-related compounds, a number of staurosporine analogues have been isolated from different microorganisms. In addition, a number of staurosporine analogues have been synthesized to improve the poor selectivity and target specificity of staurosporine which limited its clinical effectiveness. The review addresses staurosporine analogues from both microbial and synthetic sources and their biological activities.</P>

Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study

Al-Shehri, Eman Z.,Al-Zain, Afnan O.,Sabrah, Alaa H.,Al-Angari, Sarah S.,Dehailan, Laila Al,Eckert, George J.,Ozcan, Mutlu,Platt, Jeffrey A.,Bottino, Marco C. The Korean Academy of Conservative Dentistry 2017 Restorative Dentistry & Endodontics Vol.42 No.3

Objectives: To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide ($Al_2O_3$) particles at different pressures. Materials and Methods: Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and ${\chi}^2$ tests (${\alpha}=0.05$). Results: The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. Conclusions: CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.

Pooling shrinkage estimator of reliability for exponential failure model using the sampling plan (n, C, T)

Al-Hemyari, Z.A.,Jehel, A.K. The Korean Reliability Society 2011 International Journal of Reliability and Applicati Vol.12 No.1

One of the most important problems in the estimation of the parameter of the failure model, is the cost of experimental sampling units, which can be reduced by using any prior information available about ${\theta}$, and devising a two-stage pooling shrunken estimation procedure. We have proposed an estimator of the reliability function (R(t)) of the exponential model using two-stage time censored data when a prior value about the unknown parameter (${\theta}$) is available from the past. To compare the performance of the proposed estimator with the classical estimator, computer intensive calculations for bias, mean squared error, relative efficiency, expected sample size and percentage of the overall sample size saved expressions, were done for varying the constants involved in the proposed estimator (${\tilde{R}}$(t)).

Analyzing dynamic characteristics of nonlocal porous graded beams under impulse and thermal loading

Al-Toki, Mouayed H.Z.,Fenjan, Raad M.,Ahmed, Ridha A.,Faleh, Nadhim M.,Abdullah, Wael Najm Techno-Press 2021 Advances in computational design Vol.6 No.4

In the framework of nonlocal strain gradient theory, the dynamic responses of a porous functionally graded (FG) nano-size beam under half-sine impulse load and thermal environment. The half-sine impulse load has been modeled as a point load located on the top surface of the nano-size beam. The exerted impulse load leads to the transient vibrations of the nano-size beam at a prescribed time. The porous beam has been described with two pore distributions named even-type and uneven-type pores. The formulation has been developed based upon the refined beam model while the equations will be solved numerically using differential quadrature (DQ) method. Finally, the dynamic deflections in transient region will be derived with the usage of Laplace transform technique. It will be indicated that temperature variation, pore distribution and nano-scale factors have remarkable influences on dynamic resonse of the nano-size beam subjected to sine-type impulse loads.

Shear behavior of RC beams externally strengthened and anchored with CFRP composites

Al-Rousan, Rajai Z. Techno-Press 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.4

The primary objective of this paper is to study the effectiveness of anchorage on the performance of shear deficient beams externally strengthened with CFRP composites. The overall behavior of the tested beams loaded up to failure, the onset of the cracking, and crack development with increased load and ductility were described. The use of CFRP composites is an effective technique to enhance the shear capacity of RC beams by using CFRP strips anchored into the tension side and from the top by 15-34% based on the investigated variables. Bonded anchorage of CFRP strips with width of 0.1h-0.3h to the beam resulted in a decrease in average interface bond stress and an increase in the effective strain of the FRP sheet at failure, which resulted in a higher shear capacity as compared with that of the U-wrapped beams without anchorage as well as delay or mitigate the sheet debonding from the concrete surface.

Time-dependent stresses and curvatures in cracked R.C. sections under working loads

Al-Zaid, Rajeh Z. Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.18 No.3

The present study provides a relatively simple and accurate analytical model for the prediction of time-dependent stresses and curvatures of cracked R.C. sections under working loads. A more simplified solution is also provided. The proposed models are demonstrated by considering a numerical example and conducting a parametric study on the effects of relevant R.C. design parameters. In contrary to tension reinforcement, the compression reinforcement is found to contribute significantly in reducing tensile stresses in tension steel and in reducing the total section curvatures. The good accuracy of the proposed approximate solution opens a new vision towards a simple yet accurate model for the prediction of time-dependent effects in R.C. structures.

On simple estimation technique for the reliability of exponential lifetime model

Al-Hemyari, Z.A.,Al-Saidy, Obaid M.,Al-Ali, A.R. The Korean Reliability Society 2013 International Journal of Reliability and Applicati Vol.14 No.2

Exponential distribution plays a key role in engineering reliability and its applications. The exponential failure model has been studied for years. This article introduces two new preliminary test estimators for the reliability function (R(t)) in complete and censored samples from the exponential model with the use of a prior estimation (${\theta}_0$) of the mean (${\theta}$). The proposed preliminary test estimators are studied and compared numerically with the existing estimators. Computer-intensive calculations for bias and relative efficiency show that for, different values of levels of significance and for varying constants involved in the proposed estimators, the proposed estimators are far better than classical and existing estimators.