魔環
假設G為簡單圖,令V(G)、E(G)分別為G的頂點與邊所形成的集合,|V(G)|與|E(G)|分別代表G的頂點集合與邊集合的元素個數。若u, v∈V(G)且u, v有邊相連,則將此邊記為uv∈E(G)。對於給定的填單圖G,若存在函數f: V(G)∪E(G)→{1, 2, 3,…, m},其中m=|V(G)|+|E(G)|且函數f滿足下列兩個條件: (1)f為1-1且映成函數: (2)對於每個邊uv∈E(G),f(u)+f(v)+f(uv)恆為定值T, 則稱函數f為圖G的一個『魔函數』,G為一個具有『魔和』為T的『魔圖』。 在此次研究中,我們證明了下列的結果: 1.任意圈Cn為具有魔和[(5n+4)/2]或[(7n+3)/2]的魔圖; 2.長度為奇數n的圈Cn,其中n≠5,為具有魔和(5n+5)/2的魔圖; 3.長度為n=4t+2(t≧1)的偶圈Cn,為具有魔和(5n+6)/2的魔圖; 4.長度為奇數n的圈Cn外加兩個相鄰的懸掛邊所成為的圖為一個魔圖; 5.三個具有共同端點的n-路徑所形成的圖為一個魔圖。
Green Wastewater Treatment: Using Graphene Oxide produced from Date Pits to Degrade Organic Dyes via Novel Microwave Technique
Water treatment is considered as one of the top research priorities in Saudi Arabia. It has been reported by World Health Organization that, 50,000 people die every day from diseases caused by contaminated water. This research attempts to degrade organic pollutants present in wastewater by using Graphene Oxide synthesized from Saudi natural source. Physical activation of date pits was carried out by carbonizing the samples at different temperatures to produce active carbon. Hammer’s method was employed for the purpose of Graphene Oxide production. The resulted Graphene Oxide has been characterized using FT-Raman, XRD and SEM techniques. Methylene Blue (MB) dye was used as a model organic pollutants to examine the ability of Graphene with the aid of a microwave-system to remove such pollutants. A modified domestic MS furnace with a variable power was used to supply microwave energy. The MB solution 2.5x10-6M was mixed with 0.1gm of Graphene Oxide. The applied microwave power was ranged between 100 to 700 W and the time was set between 0 to 12 minutes. The samples were centrifuged and then filtered through a millipore filter to remove the Graphene Oxide dispersed particles. It is found that, 98% of the initial concentration of MB is removed effectively within 12 minutes under microwave power of 500 W. Chemical oxygen demand is shifted from 450 to 87 mg/L while biological oxygen demand was decreased from 270 to 12.8 mg/L which indicating the degradation of organic constituents. This method can be used for water purification from organic pollutants.