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This is an Open Access Journal

Open Access journal
ISSN (Print) 2224-3224 - ISSN (Online) 2225-0956
Published by International Institute for Science, Technology and Education (IISTE)

[30 journals]

Applications of Microwave in Organic Synthesis: A One-step Synthesis of Ribonucleosides using natural phosphate as solid catalyst
- Authors: Driss Ouzebla|Hassan B. Lazrek|Michael Smietana|Jean-Jacques Vasseur
  Abstract: A clean, efficient and fast method for synthesis of ribonucleosides was developed, using natural phosphate as solid catalyst catalysts supported in a solid phase promoted by MW irradiation. Keywords: Natural phosphate, Ribonucleosides , Micowave irradiation .
  Issue No: Vol. 3
Catalytic Cracking of Polypropylene Waste over Zeolite Beta
- Authors: Katnanipa Wanchai|Aticha Chaisuwan
  Abstract: Catalytic cracking of polypropylene (PP) waste has been investigated using zeolite beta (BEA) as a catalyst. BEA was performed by transformation of mesoporous silica SBA-15, a novel synthesis based on the functionalization of Si/Al ratio was studied. The catalyst samples obtained were tested for their catalytic activities in the cracking of PP waste in batch reactor under various conditions. The plastic conversions and the yields of products fractions obviously depend on the the Si/Al ratios and reaction temperatures. The product selectivity is affected by those factors. The thermal cracking of PP waste leads to plastic %conversion lower than catalytic cracking. In contrast, the nanoparticle BEA is found very active up to 95 %conversion. The used catalyst can be regenerated easily by calcination and its activity remains comparable to the fresh catalyst. Keywords: Zeolite beta, Catalytic cracking, Thermal cracking, Polypropylene (PP) waste, %conversion
  Issue No: Vol. 3
Thermodynamic Parameters of the Uncatalyzed Redox Reaction Between Potassium Peroxydisulphate and D(+)Glucose
- Authors: M. J. A. Abualreish|Ahmad Desoky M. Mohamad
  Abstract: The uncatalyzed redox reaction between potassium peroxydisulphate and D(+) glucose was studied titremetically . The progress of the reaction was followed by examining the concentration of potassium peroxydisulphate in the reaction mixture at different time intervals by iodometric titration method. Thermodynamic parameters, activation energy (Ea), frequency factor (A), entropy change (?S) and the free energy change (?G) of the uncatalyzed redox reaction were evaluated from the values of the fractional order rate constants ko at different temperatures. Keywords: Uncatalyzed redox reaction, thermodynamic parameters, D(+)glucose, Potassium peroxydisulphate.
  Issue No: Vol. 3
Textured concrete as an alternative cladding material instead of stone case of Amman
- Authors: Taiseer Al-Rawashdeh
  Abstract: Many cladding materials can be found to cover facades, this study search about if the textured concrete can be an alternative cladding material to be used for facades instead of stone in Amman city with knowing that the textured concrete is an affordable material in Jordan and may offer the natural look of stone cladding. Keywords: Textured concrete, stone cladding
  Issue No: Vol. 3
Synthesis, Characterization and Effect of ?-Ray on Rare-Earth Tb3+ Doped Nano LiMn2-xTbxO4 Lithium Manganates
- Authors: Morsi M. Abou-Sekkina|Abdalla M. Khedr|Fouad G. El-Metwaly
  Abstract: Pure nano lithium manganese oxide spinel (LiMn2O4) and doped Tb3+ lithium manganese oxide spinel, [LiMn2-xTbxO4, (x = 0.01%, 0.02%)], are synthesized via solid-state method. The synthesized LiMn1.99Tb0.01O4 was irradiated by ?-irradiation with 30 kGy. The resulting spinel product is characterized by various methods such as thermo gravimetric and differential thermal analysis (TG/DTA), infrared (IR) spectroscopy, x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive of x-rays analysis (EDAX), electron spin resonances (ESR) studies and DC–electrical conductivity measurements. The XRD and SEM confirm the nano materials size for all prepared samples. DC–electrical conductivity measurements indicates that these samples are semiconductor and the activation energy decreases with increasing rare-earth Tb3+ content; ?Ea= 0.427 eV for LiMn1.99Tb0.01O4, ?Ea= 0.339 eV for LiMn1.98Tb0.02O4 and decreases to ?Ea= 0.330 eV for ?-irradiation of LiMn1.99Tb0.01O4 nano spinel thus in role increases its attractiveness in modern electronic technology. Abou-Sekkina activation energy for the induced ?-irradiation is evaluated for the first time, which was found to be 0.097 eV. Keywords: Nano lithium manganates, Tb3+ doping spinel, ? –Ray effect
  Issue No: Vol. 3
SARA Separation and Determination of Concentration Levels of Some Heavy Metals in Organic Fractions of Nigerian Crude Oil
- Authors: I. Muhammad|N. Tijjani|I.J. Dioha|A. Musa|H. Sale|A.M. Lawal
  Abstract: Nigerian Crude oil samples were obtained from Nigerian Petroleum Development Company (NPDC). The samples were subjected to column chromatography. Sequential leaching method was used to separate the crude oil into four distinct fractions based on leaching of crude oil with different organic solvents and mixtures. Saturated fraction was extracted with hexane- cyclohexane (1:1v/v), aromatic fraction was extracted with hexane- toluene (7:3v/v), while resin was extracted with tetrachloromethane-trichloromethane (7:3v/v), and asphaltene was extracted with acetonitrile-methanol (1:1v/v). The fractions were digested using sulphuric acid, nitric acid and hydrochloric acid method followed by the detection of metals in the samples using AAS analysis. The elements analyzed were Pb, Cu, Cr, Fe and Ni. The result shows that Fe had the highest concentration while Ni had the least concentration. The concentration (ppm) levels of these elements in the crude oil fraction analyzed range from 0.1307 – 0.4107 for Pb, 0.1796 – 1.1250 for Cu, 2.7420 – 10.1903 for Cr, 11.2962 – 21.8084 for Fe, and 0.0464 – 0.5876 for Ni. It was obvious from this study and previous ones that Nigerian crude oil fractions have low metal content. However, despite their low concentrations they can still be detrimental to the refinery operations and the immediate environment, and therefore, should be removed before refining. Keywords: Atomic Absorption Spectroscopy, Aromatic, Asphaltenes, Risens, Saturates, Heavy Metals
  Issue No: Vol. 3
Effect of Occupation on the Levels of Lead in Human Blood in Kenya
- Authors: Richard Mogwasi|Benuel Nyagaka|Enock Okiambe|Hudson Nyambaka|Jane Murungi|Zachary Getenga|Enock Amboga|Evans Onyancha|Samuel Abuga|Evans Kenanda
  Abstract: The occupation an individual is involved in exposes him or her to different levels of lead from the work environment. The main occupation of the study subjects included working in the petrol stations, teaching, nursing, street hawking, doing clerical work, working in public vehicles, farming and schooling. The aim of the study was to determine the effect of occupation on the lead levels in human blood in Nairobi City and Nyamira District, Kenya. The subjects involved in the different occupations were randomly selected and recruited for the study. The study used a questionnaire to assess lead exposure factors of the recruits, while atomic absorption spectroscopy and differential pulse anodic stripping voltammetry were used for determining the lead levels. The street hawkers in Nairobi City centre had the highest mean blood lead level of 36.85?16.98 ?g/ dl while the teachers of Nyamira Town had the lowest mean blood lead level of 8.1?5.3 ?g/ dl. The study provides an additional data pointing to elevated blood lead levels in occupationally exposed individuals. Key words: Occupational exposure, BPb, AAS, DPASV.
  Issue No: Vol. 3
Non-Destructive Evaluation of Corrosion on Insulated Pipe using Double Wall Radiographic Technique
- Authors: Alexander Boateng|K.A. Danso|C.P.K. Dagadu
  Abstract: The research explored the Double Wall Radiographic inspection technique using Ir-192 for evaluating deposits and corrosion attacks across the inner and outer walls of an insulated steel pipe .The experiment was performed on a designed test piece to simulate corrosion attacks and deposits on industrial pipes. From the relationship curve drawn between the radiographic film density and the thickness of the pipe, the attenuation coefficient of the insulating material was negligible compared to the concrete deposit. The Double Wall Technique (DWT) had a maximum underestimation of 1.3% of the corroded surface area of the pipe and was within an accuracy of ± 0.29. This tolerance limit is 5% less than the wall thickness of the pipe. From the results obtained, effective corrosion monitoring of insulated pipes can reliably be executed by the DWT without the costly removal of insulation material. Keywords: Double Wall Radiography, Corrosion, Insulated Pipe, Ir-192, Attenuation Coefficient.
  Issue No: Vol. 3
Synthesis, Mesomorphic and Molar Conductivity Studies of some Macrocyclic Phthalocyanine Palladium (II)
- Authors: Ali Kareem A. Al-Lami|Nesreen N. Majeed|Ali H. Al-Mowali
  Abstract: Two series of Macrocyclic Phthalocyanine Palladium(II) namely 4,4,4,4-RnPcPd and 3,3,3,3-RnPcPd were prepared and characterized. The mesomorphic investigation by hot stage polarizing microscope for these series was carried out. This investigation revealed that the 4,4,4,4-RnPcPd series exhibited columner mesophases while the second series 3,3,3,3-RnPcPd did not show any liquid crystalline properties.The molar conductivity measurments carried out in dimethyl sulfoxide and N,N-dimethyl formamide solvents for all prepared compounds at room temperature indicate that these compounds behave as weak electrolytes . Keywords: Macrocyclic compounds, Macrocyclic complexes, Liquid Crystals, Conductivity.
  Issue No: Vol. 3
Extraction and characterization of Amorphous Silica from Corn Cob Ash by Sol-Gel Method
- Authors: E. A. Okoronkwo|P. E. Imoisili|S.O.O. Olusunle
  Abstract: Extraction of amorphous silica from Corn cob Ash (CCA) was carried out in this study. Silica xerogel was produced by dissolving CCA with alkali solution to form sodium silicate solution and lowering the pH to7.0 by adding hydrochloric acid to form silica aquagel followed by drying to form silica xerogel. The silica xerogel was characterized using XRF, XRD and FTIR techniques. Silica and mineral contents of CCA and xerogel were determined by XRF, X-ray diffraction patterns revealed amorphous nature of extracted silica. Fourier transform infrared (FTIR) data indicated the presence of siloxane and silanol groups. Silica yield from CCA was 52.32% while moisture content was 2.89%. Keywords: corn cob ash; amorphous silica; xerogel; aquagel
  Issue No: Vol. 3
Effect of tool offset and tilt angle on weld strength of butt joint friction stir welded specimens of AA2024 aluminum alloy welded to commercial pure cupper
- Authors: Moneer H. Tolephih|Hatem M. Mahmood|Athra`a H. Hashem|Esam T. Abdullah
  Abstract: The aim of the present work is to investigate the mechanical properties and microstructure of butt joints friction stir welded (FSW) of dissimilar material specimens welded with single pass .The material used is AA2024 aluminum alloy 5 mm thick and pure commercial copper .20 mm Flat shoulder tool 6 mm Pin diameter with a rotational speed of 900 rpm and 25 mm/min feed is used in this work ,the tool is tilted 2o to the Z axes of the machine. The welded specimens have been tensile tested at room temperature in order to analyze the mechanical properties with respect to the parent metals. The microstructure of the welded specimens has been studied by employing optical microscopy. Micro-hardness examination is also performed on the welded specimens. FSW specimens welded with flat shoulder tool and 2o tilt angle showed higher ultimate stress than the specimens welded with flat shoulder tool and zero tilt angle . Specimens welded with 1 mm pin offset showed higher strength than the specimens welded with 0.5 and 1.5 mm pin offset. Keywords: Friction stir welding, subsequent passes , mechanical properties
  Issue No: Vol. 3