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Copyright of International Journal of Engineering Transactions B: Applications is the property of International Journal of Engineering (IJE) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Statement of Problem: One of the factors affecting the degree of polymerization of light-cured composites is the type of light-curing unit used. In addition, physicomechanical properties of the composite resins depend on the degree of conversion and polymerization. Objectives: Since the type of initiator in new composite resins is not explained by manufacturers, this study is an attempt to compare the depth of hardening, with two LED and QTH light-curing units. Materials and Methods: Fifteen samples prepared from Gradia Direct and Filtek Z250, both of which being universal, were cured with QTH (Astralis 7) and LED (Bluephase C8) light-curing units. All the samples were molded in polyester resin and cut from the middle by a disk. The hardness of the cut area was evaluated at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5 and 4-mm depth intervals and also at the same interval as the width of the sample, with Vickers hardness machine, while the samples were placed in a darkroom. Data were statistically analyzed using one-way ANOVA, two-way ANOVA, t-test and post Hoc Tukey’s tests in SPSS, version 16. Results: Filtek Z250 was harder than Gradia Direct at all the depth with both light-curing units. The hardness of Filtek Z250 sample cured with Astralis 7 was higher than that cured with LED, but with Gradia Direct the LED unit resulted in higher hardness. Curing depth was not significantly different between the groups (p = 0.109). Conclusions: Vickers hardness number for both composites used in this study is in an acceptable range for clinical implications. The composites’ composition is important to be considered for selection of light unit. Based on the findings of the present study, LED did not present more curing depth compared with QTH.

The present research aims to investigate the two-phase air/water flow in a vertical pipe using an electrical resistance sensor and a high-speed camera. An electrical resistance sensor is designed and embedded in the inner wall of the tube. A flow pattern map is drawn at the height of 270 cm from the testbed inlet for 320 different phase velocities using a high-speed camera. By measuring the output voltage of the electrical resistance sensor and using the Maxwell relation, the volume fraction in bubbly and slug flow regimes are calculated for different phase velocities. The volume fraction values detected from the output signal of the electrical resistance sensor are compared with the results obtained from the high-speed camera images. The width of the output signal from the electrical resistance sensor indicates the length of the Taylor bubble. The output signal width is compared to the obtained Taylor bubble length from high-speed camera images, for several different velocities of the phases. It is noticed that at a constant velocity of the phases, the output signal width from the sensor is linearly related to the length of the Taylor bubble. The variations of the output signal width are plotted in terms of the ratio of the Taylor bubble length to the summation of air and water superficial velocities. By linear fitting of the available data, a novel equation is presented to calculate the Taylor bubble length in terms of the signal output from the electrical resistance sensor and the total superficial velocity of the phases. [ABSTRACT FROM AUTHOR]

Background and Objectives: Cadmium is a toxic metal which is widely used in industry. This metal exerts toxic effects on multiple organs, including nervous system. The aim of this study is to evaluate the effect of cadmium on weight and development of hippocampus in Wistar rat embryos and then determining whether L-carnitine, as an antioxidant, can protect hippocampus from the toxic effects.Methods: Female Wistar rats (250-300g) were used in this study. 24 hours after mating with male rats, the females were separated and their vaginal smears were examined for sperm detection. This day was considered as embryonic zero day. The female rats were divided into three groups: The control group which received no injection, the experimental group 1 which received 1mg/kg B.W cadmium and the experimental group 2 which received 1mg/kg B.W cadmium+500mg/kg B.W L-carnitin in days 7 and 10 of gestation. On day 17 of gestation, the animals were sacrificed by chloroform over dose and their embryos were removed surgically. The embryos were fixed in formalin 10% for 30 days, the weight of embryos were measured. Then tissue processing, sectioning and Hematoxylin-Eosin (H & M) staining were done. Some sections of hippocampus were evaluated using light microscope and MOTIC soft ware. Results: The weight of embryos were significantly decreased in experimental groups. This decrease was significantly greater in the Experimental group 2. The number of cells and thickness of hippocampus layers were decreased significantly just in the second group. Conclusion: These findings indicate that cadmium has teratogenic effects on embryo’s weight and development of hippocampus and at least a part of these effects may be inhibited by L-carnitine.