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Due to rapid depletion of fossil energy sources and increasing the environmental pollution through high fossil energy consumption, an alternative renewable and clean energy carrier as hydrogen is requested more investigations in order to get the optimal request by DOE. In this study, a deepest study on SiC nanocones is done including both of the geometrical and electronic properties of all possible five different disclination angles as a function of size using density functional (DFT) calculations at the B3LYP/6-31g level of theory. Then the hydrogen adsorption mechanism is investigated on three different sites: H S1 (above the first neighbor atom of the apex atoms), H S2 (above one atom of the apex atoms) and H S3 (above one atom far from the apex atoms). Our calculations show that the most candidate SiC nanocone structure for hydrogen storage is Si 41 N 49 H 10-HS 2-M1-Type 2 with disclination angle 300˚. In addition, our results indicate that the hydrogen adsorption induced the energy gap to decrease. Hence, these results indicate that the SiCNCs can be considered as a good candidate for hydrogen storage.

A systematic computational study of surface reactivity for pure and mono-hydrogenated carbon nanocoes (CNCs) formed from graphene sheets as functions of disclination angle, cone size and hydrogenation sites has been investigated through density functional (DFT) calculations and at the B3LYP/3-21G level of theory. Five disclination angles (60˚, 120˚, 180˚, 240˚ and 300˚) are applied and at any disclination angle four structures with different sizes are studied. For comparison, pure and mono-hydrogenated boron nitride nanocones (BNNCs) with disclination angles 60˚, 120˚, 180˚, 240˚ and 300˚ are also investigated. The hydrogenation is done on three different sites, H S1 (above the first neighbor atom of the apex atoms), H S2 (above one atom of the apex atoms) and H S3 (above one atom far from the apex atoms). Our calculations show that the highest surface reactivity for pure CNCs and BNNCs at disclination angles 60˚, 180˚ and 300˚ is 23.50 Debye for B41N49H10 cone and at disclination angles 120˚ and 240˚ is 15.30 Debye for C94H14 cone. For mono-hydrogenated CNCs, the highest surface reactivity is 22.17 Debye for C90H10-H S3 cone at angle 300˚ and for mono-hydrogenated BNNCs the highest surface reactivity is 28.97 Debye for B41N49H10-H S1 cone when the hydrogen atom is adsorbed on boron atom at cone angle 240˚.

The study aimed to investigate the effect of an educational program based on mathematical power in the development of algebraic thinking and solving algebraic problems among second intermediate grade Students in Al-Madinah Al-Munawara. The study sample consisted of 75 students who were randomly divided into two groups: an experimental group, that used an educational program based on mathematical power, and a control one that employed a traditional method. For the purposes of the study, the researcher developed a test for algebraic thinking consisting of 18 paragraphs to measure the following skills: understanding the patterns and relationships, the use of algebraic symbols, and use of multi-representation. Another test was also developed for solving algebraic problems consisting of 16 paragraphs to measure all the skills of understanding and analysis; developing a plan and its implementation, reviewing the solution; and solving algebraic problems. Validity and reliability of the tools were verified. Findings revealed that students' performance in the experimental group exceeded its counterpart on all skills relevant to algebraic thinking, and solving algebraic problems.