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    Evaluation of Phenolic Contents and Bioactivity of Root and Nutgall Extracts from Iraqian Quercus infectoria Olivier
    (Acg Publications, 2017) Hamad, Hewa Omar; Alma, Mehmet Hakki; Gulcin, Ilhami; Yilmaz, Mustafa Abdullah; Karaogul, Eyyup
    The extracts of powdered root and nutgall of Iraqian Aleppo oak (Q. infectoria) were obtained by using three different solvents along with two extraction methods. Liquid chromatography and tandem mass spectrometry (LC-MS/MS) was implemented to identify phytochemicals in the extracts. Antioxidant activity was determined by DPPH radical scavenging activity. Also, for measurement of antibacterial activity, disc diffusion and microdilution assays were used. Specifically, the nutgall extracts were found to have higher concentration of phenolic acid contents, and to some extent flavonoids and greater antioxidant and antimicrobial activities in comparison with the root extracts. Furthermore, microwave extraction technique was proven to be much more effective than conventional one in view of extraction yield for both plant parts used here.
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    Synergic effect of fly ash and calcium aluminate cement on the properties of pumice-based geopolymer mortar
    (Elsevier Sci Ltd, 2022) Karaaslan, Cemal; Yener, Engin; Bagatur, Tamer; Polat, Riza; Gul, Rustem; Alma, Mehmet Hakki
    This paper reveals the synergic effect of fly ash (FA) and calcium aluminate cement (CAC) on the properties of pumice-based geopolymer mortars. Geopolymer mortar samples produced by replacing 0, 10, 20, and 30% of the pumice with FA and/or CAC are cured at ambient temperature, and 60C degrees. Physical properties, compressive strength (7, 28, and 90-days), durability, and microstructure of these samples are investigated in this study. While CAC and heat curing greatly reduce the setting time, FA has a limited effect on the setting time. However, both FA and CAC significantly increase the workability of the mortar mix. By replacing the optimum amount of the pumice with FA and CAC, the 7-day compressive strength of heat-cured geopolymer mortars can achieve 68.0 MPa. On the other hand, CAC significantly increases the compressive strength of the geopolymer mortars and their resistance to the wetting-drying and seawater. In addition, the FA has a limited effect on the enhancement of the mechanical properties and durability of the geopolymer mortars. Efflorescence is slightly reduced by FA and CAC additives, however, is greatly reduced by heat curing. The SEM/EDS show that CAC creates C-A-S-H gel and together with FA they reduce cracks and voids in the geopolymer matrix. The findings reveal that the properties of both fresh and hardened geopolymer mortars can be improved by replacing pumice with a suitable amount of FA and CAC.