Project procurement system selection model (with particular reference to Saudi Arabia)

In the last two decades there has been a significant change in the technical and economic conditions prevailing in the construction industry. The traditional methods of procuring projects are now inadequate to cope with these changes. To overcome the shortcomings of the traditional procurement methods, the construction industry has developed a large number of different procurement systems to secure the relationships between contract parties. The proliferation of different procurement systems has created the problem of how to determine the optimum procurement system for any particular project. A systematic approach for selection of the most appropriate system is now needed. Throughout this thesis an investigation has been made of many of the issues related to the successful formulation of a Project Procurement System Selection Model (PPSSM). The knowledge of client needs in the construction industry is essential to the project success. This research has considered the fundamental role played by client needs in the process of procurement selection. The various categories of procurement system that exist in the construction industry are presented in order to address the benefits and drawbacks of each system. A careful investigation of the rules and regulations governing the Saudi construction industry has contributed very significantly to the success of the model building. An examination of the existing models revealed a number of drawbacks which are discussed in detail in this research. A survey was conducted in Saudi Arabia with the aim of testing the PPSSM for effectiveness and efficiency and assisting the governmental agencies to select the most appropriate procurement system to implement their projects. For this purpose, a questionnaire was developed and divided into three major parts: Background information; Data needed to operate PPSSM; and Evaluation of the criteria used for the selection of the procurement system. The results of the first and third parts are generated from 100 responses to the questionnaire mailed to the 110 governmental agencies that represent the population of the study, giving an overall response of (91%). For the second part only thirty senior government agency officers were involved in order to maintain consistency of data needed to operate the PPSSM. The data were analyzed using computer statistical packages: Excel and Statistical Analysis System (SAS). On the basis of the synthesis process of the PPSSM, Saudi public clients have selected "design and build" as the most appropriate procurement system to procure their projects with an overall priority of 0.49. Design and manage, construction management, and management contracting ranked second, third and fourth with priorities of 0.258, 0.140 and 0.106 respectively. The outcome of the study demonstrates the effectiveness of PPSSM in helping the client in the construction industry to choose the right procurement system that best answers his needs and fulfills the project requirements

The Chemical Chelates and a Comparative Antimicrobial Study on Some Ciprofloxacin Complexes, Spectral, Kinetic and Molecular Modeling Investigations

A series of ciproH antibiotic drug complexes was prepared. Cu(II), VO(II), Pd(II), Zn(II), Pt(II) and Pt(IV) are the metal ions used for the preparations. The chosen ions have a great history in the medicinal field which may introduce a sensitive antibiotic appearance in comparing with the free ciproH drug. All the prepared complexes are discussed briefly based on spectral ( IR, 1HNMR, 13CNMR, Uv-Vis, ESR, X- ray and SEM), thermal and analytical data. The ligand coordinates through its zwitterionic form as bidentate mod through COO- and C=O groups. The octahedral stereo structure was prepared with Cu(II), Zn(II) and Pt(IV) ions, square planer with Pd(II) and Pt(II) ions however, the square – pyramidal with VO(II) ion. The amorphous nature was proposed for all investigated complexes based on the x- ray diffraction patterns although, the nanocrystalline appearance of starting ligand. Thermogravimetric analysis is also used to support the presence or absence of solvent molecules conjugated with the complexes isolated physically or chemically. Applying Chem- office program a suitable modeling structure of each investigated complex was drawn. A comparative antibacterial study was concerned using Gramm –ve and Gramm +ve bacteria . The data reflect the inhibiting effect of some complexes more than the drug itself which is considered an introductory step in introducing competitive drug. Key words: ciprofloxacin complexes, spectral, modeling and biological activit

What does it look like to be in a mixed-gender environment? A phenomenological study of the experience of Saudi international students in a mixed-gender environment

This study provides a phenomenological investigation of the experience of Saudi international students in Australia. It focuses particularly on the experience of transitioning from a segregated to a mixed-gender environment. The study was undertaken because an increasing number of Saudi students pursue their studies in mixed-gender environments in Western countries like Australia, and there is a lack of literature that focuses on Saudi students’ cross-cultural experiences. Two general aims have guided the current research: the first aim was to explore how the experience of transitioning from a segregated to a mixed-gender environment manifested itself to Saudi international students studying in an Australian context. The second aim was to investigate the potential impact that this experience could have on the individual’s identity. To facilitate these aims, two questions were developed for the research. The major question was: What does the transitioning experience from a segregated to a mixed-gender environment look like for Saudi students in Australia? A second supplementary question was developed: What potential impact does the experience of being in a mixed-gender environment have upon the identity of Saudi international students? A phenomenological approach, influenced by a qualitative paradigm in social science research, was developed to allow the participants to describe their encountered experiences. In-depth interviews were conducted to gather data from four Saudi international students who were studying at Australian universities and sponsored by the Saudi Arabian Ministry of High Education. The participants were three males and one female. Phenomenological explication of the data indicated that the experience of transitioning from a segregated to a mixed-gender environment appeared to be constituted by two essential structures: the first was the developmental structure, which constituted the positive meanings made about the phenomenon. The second structure was the psychological complex associated with mixing with the opposite sex that informed the challenges and obstacles involved in the transition. Issues relate to engagements with the Australian community, and the participants’ previous experience in a mixed-gender environment appeared to be an influential part of the individuals’ experiences. Significant indications were found to support the research assumption that dialogical and dialectical influences occur between international students’ cultural identity and the formation of the cross-cultural transitioning experience. The significance of this research lies with the growing number of international students in Australia, including those from Saudi Arabia, and the acknowledgment that students from Saudi Arabia come from a unique context and would, therefore, encounter different experiences of enculturation to students from other cultures. The research contains implications for the theory, policy, and practice of the Australian and Saudi Arabian governments and the host educational institutions

Optimization of chloroxylenol degradation by Aspergillus niger using Plackett-Burman design and response surface methodology

Chloroxylenol is a very toxic phenolic derivative and it represents potential hazard towards human health and to the environment. Aspergillus niger, local isolate, is an efficient fungus to degrade 99.72% of 2 mg/L of chloroxylenol after 7 days of fermentation. It also has a high capacity to degrade 91.83% of higher chloroxylenol concentration of 20 mg/L after 6 days of incubation on mineral medium amended with 2 g/L of glucose. Statistical experimental designs were used to optimize the process of chloroxylenol degradation by the fungus. The most important factors influencing chloroxylenol degradation, as identified by a two-level Plackett-Burman design with 11 variables, were NaCl, (NH4)2SO4, and inoculums size. Response surface analysis was adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum chloroxylenol degradation. Under the optimized medium compositions and culture conditions, A. niger was able to degrade completely (100%) chloroxylenol (20 mg/L) after 134.6 h of fermentation. The predicted values of Plackett-Burman conditions and response surface methodology were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. Optimal conditions obtained in this work laid to a solid foundation for further use of A. niger in treatment of high strength chloroxylenol polluted effluents. So, the optimized conditions were applied to bioremediate crude sewage containing 27.8 mg/L of chloroxylenol by A. niger. The fungus efficiently degraded chloroxylenol after 8 days of fermentation.Key words: Chloroxylenol degradation, Aspergillus niger, Plackett-Burman design, Response surface methodology

The Effectiveness of Experiential Learning on SDGs Awareness in Saudi Sixth Graders

The study aimed to reveal the effectiveness of using experiential learning in teaching science to develop the concepts of the United Nations goals for the principles of sustainable development by 2030 and raise awareness of them among sixth-grade students. The study employed a semi-experimental approach with two groups: an experimental group (20 students) who were taught using the developed unit, and a control group (20 students) who were taught using the prescribed unit from the regular curriculum. The groups were intentionally selected to ensure cooperation and ease of implementing the experiment on the sample. The tools used included the preparation of an achievement test for the concepts of the United Nations Development Goals. The results of the study showed a statistically significant difference, at a level of significance (α ≤ 0.05), between the mean scores of the control and experimental groups in the application of the achievement test and the awareness scale, favoring the experimental group. This indicates the effectiveness of the developed unit. The study also recommended conducting further research to incorporate experiential learning into science curricula and suggested that decision-makers at the Ministry of Education include the United Nations Sustainable Development Goals 2030 in science curricula

Synthesis, characterization, thermal analysis and biological study of new thiophene derivative containing o-aminobenzoic acid ligand and its Mn(II), Cu(II) and Co(II) metal complexes

New ligand containing 2-(2,4-dioxo-4-thiophen-2-yl-butyrylamino)-benzoic acid (HL) merged moiety was synthesized and characterized by FT-IR, elemental analyses, mass spectra and 1H-NMR spectral. In the present study, the attempts were carried to form complexes of HL ligand with some transition metal ions (MnII, CuII and CoII) of well-defined at the (1:1) ratio of the components in the dimethyl sulfoxide (DMSO) solvent. All complexes have been studied by FTIR spectra, elemental analyses, thermal analysis, molar conductivity, electronic spectra and magnetic moment. The HL ligand produced as a bidentate chelate with interactive metal ions. All the results suggested octahedral geometry to complexes and have the formulae [M(HL)(Cl)2(H2O)2].nH2O where M = Mn(II), Cu(II) and Co(II). The IR spectra of the complexes were assigned and compared with the data in literature. The kinetic and thermodynamic results such as E*, ΔH*, ΔS* and ΔG* were calculated based o the TGA/DTG curves using Coats and Redfern and Horowitz and Metzger approximation methods. Furthermore, the resultant complexes were evaluated for the anti-bacterial and anti-fungal potential.                     KEY WORDS: 2-(2,4-Dioxo-4-thiophen-2-yl-butyrylamino)-benzoic acid, Transition metal complexes, FTIR, TGA, Antimicrobial test   Bull. Chem. Soc. Ethiop. 2021, 35(1), 129-140. DOI: https://dx.doi.org/10.4314/bcse.v35i1.1

Solvent free synthesis of hydrazine carbothioamide derivatives as a precursor in the preparation of new mononuclear Mn(II), Cu(II), and Zn(II) complexes: Spectroscopic characterizations

ABSTRACT. Over the last few years considerable attention has been devoted to the study of Schiff base complexes of metal(II) containing nitrogen, oxygen and sulfur donor ligands due to their diverse biological activities. Therefore, the Schiff base thiosemicarbazone derivatives of 2-(2-hydroxy-3-methoxybenzylidene) hydrazine carbothioamide (HL1) and 2-(4-bromo-2-hydroxy-3-methoxybenzylidene) hydrazine carbothioamide (HL2) were synthesized with solvent free technique using silica gel as material support for the reaction. The structures of the precursor’s organic products confirmed with their 1H, 13C NMR, IR and microanalysis data. Six new manganese(II), copper(II), and zinc(II) complexes of HL1 and HL2 2-(2-hydroxy-3-methoxybenzylidene) hydrazinecarbothioamide derivatives with the general formulation [ML1Cl] and [ML2Cl], where M = Mn2+, Cu2+, and Zn2+ were prepared and well discussed by using elemental analyses, magnetic moments, molar conductance, infrared and electronic spectral techniques. The assignments data of spectroscopic analysis confirm that the synthesized thiosemicarbazone Schiff bases of acts as a tridentate ligand as sulfur-oxygen-nitrogen donating atoms. The values of magnetic moments agreed with the data of electronic spectra which both suggested a four-coordination geometry of the synthesized complexes.                     KEY WORDS: Schiff base, Thiosemicarbazone, Manganese(II) complex, Copper(II) complex, Zinc(II) complex   Bull. Chem. Soc. Ethiop. 2021, 35(2), 413-424. DOI: https://dx.doi.org/10.4314/bcse.v35i2.1

In situ acetonitrile/water mixed solvents: An ecofriendly synthesis and structure Explanations of Cu(II), Co(II), and Ni(II) complexes of thioxoimidazolidine

ABSTRACT. The bidentate oxoacetate derivative of 4-oxo-2-thiazolidine 4ligand (L1) synthesized by the reaction of 1-(1-(Pyridin-3-yl)ethylideneamino)-2-thioxoimidazolidin-4-one 3 with diethyl oxalate with both traditional and microwave irradiation methods. The metal ion complexes of mixed ligands L1 and L2 (acetonitrile) were prepared by condensation a solution mixture of Co(II) Ni(II), and Cu(ІІ) metal chloride salts with the ligands (L1 and L2) in distilled water with stirring. The complexes were characterized by the micro analysis (C, H, N), chloride content, FT-IR, UV-Vis spectra, thermal gravimetric analysis (TGA), molar conductivity as well as magnetic susceptibility measurement. According to the obtained data the suggested coordination geometries of these complexes were suggested as octahedral structure. All the synthesized complexes were found to be electrolyte due to the presence of chloride ions outside the coordination sphere. The antibacterial activity of the L1 ligand and their metal ion complexes have been studied by screening against various microorganisms, G+ bacteria (Bacillus subtillis, Streptococcus pneumonia, and Staphyloccoccus aurease), G-bacteria (E. coli, and Pesudomonas Sp.) and fungi (Aspergillus nigaer, and Penicillium Sp.). The metal ion complexes gave the formulae: [M(L1)(L2)2(H2O)2]Cl2where M = Co(II) Ni(II), and Cu(ІІ).                     KEY WORDS: Imidazolidine, Microwave irradiation, Transition metals complexes, Biological activity   Bull. Chem. Soc. Ethiop. 2021, 35(2), 351-364. DOI: https://dx.doi.org/10.4314/bcse.v35i2.1

Synthesis, characterization and microstructural evaluation of ZnO nanoparticles by William-Hall and size-strain plot methods

ABSTRACT. At various calcination temperatures 450, 550 and 650 °C, zinc oxide nanoparticles were produced. Calcinated ZnO has high surface area as the BET was 119.12 m2g–1 and the average particle radius was calculated to be 1.16 nm. The dimension of crystallites and straining in ZnO nanoparticles' diffraction peaks remained measured. The Williamson–Hall (W–H) technique besides the size–strain approach stayed used. For each of XRD reflection peaks, physical characteristics like strain and stress were computed. Towards regulate the magnitude of crystallites, the Williamson–Hall (W–H) approach besides the size–strain technique are used that is good agreement with the size that determine from SEM as it was 22.6, 26.6 and 32.6 nm for ZnO calcinated at 450, 550 and 650 oC, individually. Using the W–H plot to modify the subversion shape, assuming an unvarying distortion model (UDM), unvarying stress deformation model (USDM), unvarying deformation energy density model (UDEDM), and The size–strain plan (SSP) approach was used to determine this. The SEM and Scherrer methods match well with the crystal size of ZnO NPs determined using W–H plots and the SSP technique.     KEY WORDS: Zinc oxide nanosphere, Calcination, Physical characterization, W–H investigation, SSP technique Bull. Chem. Soc. Ethiop. 2022, 36(4), 815-829.                                                           DOI: https://dx.doi.org/10.4314/bcse.v36i4.8                                                       &nbsp