ABSTRACT Background: Bracket rebonding is a common problem in orthodontics which may result in many drawbacks. The aims of this study were to evaluate the effects of application of two enamel protective agents “Icon†and “ProSeal†on shear bond strength before and after rebonding of stainless steel orthodontic brackets using conventional orthodontic adhesive and to assess the site of bond failure. Materials and methods: Fifty sound extracted human upper first premolar teeth were selected and randomly divided into two equal groups; the first time bonding and the rebonding groups (n=30). Each group was subdivided into control, Icon and ProSeal subgroups. The enamel protective agents were applied after etching (preconditioners). Shear bond strength before and after rebonding of stainless steel brackets were assessed using the Universal testing machine and the adhesive remnant index was used to find out the bond failure site using a stereomicroscope. Then the results were statistically analyzed using one-way ANOVA analysis test and T-test. Results: There were no significant differences in the shear bond strength mean values in either group or their corresponding subgroups. Forty percentage of the bond failure in ProSeal groups occurred away from the enamel where 75% of those were at the enamel protective agents/adhesive interface. Conclusions: The application of Icon and ProSeal did not compromise the shear bond strength and the application of the ProSeal may protect the enamel surface from trauma (cracks, chipping or detachment).
New types of hydrodesulfurization (HDS) catalyst Re-Ni-Mo/ γ-Al2O3 was prepared and tested separately with two prepared conventional HDS catalysts (Ni-Mo/ γ-Al2O3 and Co-Mo//γ-Al2O3) by using a pilot plant hydrotreatment unit. Activities of three prepared hydrodesulfurization catalysts were examined in hydrodesulfurization (HDS) of atmospheric gas oil at different temperatures 275 to 350 °C and LHSV 1 to 4 h-1, the reactions conducted under constant pressure 40 bar and H2/HC ratio 500 ml/ml .Moreover, the hydrogenation of aromatic (HAD) in gas oil has been studied. HDS was much improved by adding promoter Re to the Ni-Mo/Al2O3 catalyst. The results showed that Re-Ni-Mo/ γ-Al2O3 have more activity in desulfurization than Ni-Mo//γ-Al2O3
... Show MoreCerium oxide (CeO2), or ceria, has gained increasing interest owing to its excellent catalytic applications. Under the framework of density functional theory (DFT), this contribution demonstrates the eect that introducing the element nickel (Ni) into the ceria lattice has on its electronic, structural, and optical characteristics. Electronic density of states (DOSs) analysis shows that Ni integration leads to a shrinkage of Ce 4f states and improvement of Ni 3d states in the bottom of the conduction band. Furthermore, the calculated optical absorption spectra of an Ni-doped CeO2 system shifts towards longer visible light and infrared regions. Results indicate that Ni-doping a CeO2 system would result in a decrease of the band gap. Finally,
... Show MoreBy condensation of benzaldehyde with thiourea in absolute ethanol in the presence of glacial acetic acid as a catalyst, the Schiff base(1-benzylidenethiourea)[I] was synthesized by synthesis of 4-(3-benzylidenethioureido)-4-thioxobut-2-enoic acid compound[II] by reaction of maleic anhydride with schiff base [I] in DMF. When treating compound [II] with ammonium persulfate (NH4)2S2O8 (APS) as an ethanol initiator to obtain polymer [III], compound [III] reacted to polymer [IV] with SOCl2 in benzene. Sulfamethizole, celecoxib, salbutamol, 4-aminoantipyrine to yield polymers [V-VIII], compound [IV] reaction with different drugs. Spectral evidence established the structure of synthesized compounds: FTIR an
In this research work, synthesis, antimicrobial and antioxidant bioactivity of a chain of compounds having unsaturated ketones bond and isoxazoline moiety have been described. New chalcone derivatives containing isoxazoline moiety have been synthesized. Generally, Chalcones are unsaturated ketones bearing (-CO-CH=CH-) as reactive ketoethylenic group that give the bright yellow colored compounds due to this chromophore group. Firstly, chalcones (IIa-d) have been prepared by cyclocondensation (Claisen-Schmidt condensation) of triphenyl aminobenzaldehyde with different substituted acetophenone in ethyl alcohol to produce a series of chalcones compounds with bright yellow colored as a
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It is clear to everyone how important it is to implement transactions electronically, as it facilitates the provision of services to beneficiaries, whether individuals or institutions, to achieve many benefits that are not exclusive to the beneficiary or the applicant, but extends to the governmental and international bodies. And the number of users has reached millions since its emergence in 1995, because the concepts of electronic transactions have great advantages for the economy in general and the banking sector in particular, so cooperation in various fields with the aim of becoming an information society has become paramount, It allows customers to pay money to any company they want t
... Show MoreThe aim of study was making comparison in some kinematics variables in (100) meter butterfly swimming to first and second ranking in championship 2003 Espana, so noticed there is no such like this study in our country in comparison study for international champions therefore not specific and scientific discovering to these advanced levels, also the researchers depend on group of kinematics variables when the comparison making and it was included (50 meter the first, 50 meter the second, the differences between the first (50) meter and the second , more over basic variables in (100) meter butterfly , after having the results and treat it statistically the researchers reaches to two conclusions which was: • Success the first rank in startin
... Show MoreStaphylococcus aureus and Pseudomonas aeruginosa are the major globally distributed pathogens, which causes chronic and recalcitrant infections due to their capacity to produce biofilms in large part. Biofilm production represents a survival strategy in these species, allowing them to endure environmental stress by altering their gene expression to match their own survival needs. In this study, we co-cultured different clinical isolates of S. aureus and P. aeruginosa as mono- and mixed-species biofilms in a full-strength Brain Heart Infusion Broth (BHI) and in a 1000-fold diluted Brain Heart Infusion Broth (BHI/1000) using Microtiter plate assay and determination of colony-forming units. Furthermore, the effect of starvation stress on the e
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Electrical magnate was designed and constructed, the optimum Magnetic flux and the effect of time on the physical properties of the alkaline (magnetic water) produced from the bottled drinking water [the total dissolved solids (TDS) or the electrical conductivity, and pH] were studied, to simulate ZamZam water in Mekka Saudi Arabia. Also, the efficiency of magnetic field from this designed electrical magnate in decreasing the TDS of sea water (of 1500 ppm NaCl Content), to convert it to water suitable for irrigation (TDS<1000 ppm) was investigated in this work.The results show that the magnetic flux from our designed electrical magnate in the range of (0.013- 0.08) Tesla and 30 minut
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