Effect of waste serpentine on the properties of basic insulating refractories

Basic insulating refractories were fabricated by the pressing route using dead-burned magnesia, pure calcined alumina, expanded perlite, and calcined waste serpentine as starting raw materials in four compositions from F1 to F4. Periclase and forsterite were major phases in F1 and F2 compositions, while spinel was also detected in the XRD patterns of F3 and F4 samples. Quantitative phase analysis showed that F4 sample sintered at 1450?°C has the highest forsterite content among all other samples. On the other hand, it has lower thermal conductivity compared to F1 to F3, and even lower than aluminosilicate IFBs with the same bulk density. It is concluded that forsterite is a highly insulating material, compared to periclase, corundum, periclase-spinel, aluminosilicates, such as mullite, etc.     

Synthesis and photovoltaic properties of mono-substituted quaterthiophenes bearing strong electron-withdrawing group

We report here on the synthesis and properties of a monosubstituted quaterthiophene derivative asymmetrically functionalized by an electron-withdrawing group using the palladium-catalyzed Stille's coupling reaction. The UV–vis absorption spectrum evidences a strong intramolecular charge transfer transition. Thus oligothiophenes act as electron donors and substituent group as acceptor. The diodes in which monosubstituted quaterthiophenes behave as organic semiconductors, exhibit a rectifying behavior. Photovoltaic measurements show moderate power conversion efficiency.     

Organization and management in construction: a new approach

Operational management theory is considered and the traditional organizational problems experienced in construction and similar organizations, created by the matrix structure of management traditionally used at head office and project levels, are discussed. A new concept that is based on the formation of small but fully- independent functional companies with contractual relationships with the parent organization is introduced. The feasibility of a management structure of this type is considered. It is concluded that the new system is potentially capable of improving the productivity of resource and service groups and creating a rational basis for sharing of professional services nationwide, while at the same time improving such matters as staff motivation, job satisfaction, personal development, unity of command, ease of communication and flexibility in organization.     

Criticism of CPM for Project Planning Analysis

Published criticism in recent years concerning the inadequacy of Critical Path Method (CPM) as a project planning tool is identified and grouped under six major headings with reference to the publications in which the criticism were contained. These are answered from the writer's field experience and from experiences published by other authors. The object of the analysis is to see whether or not CPM as a project planning tool can meet the required functions of planning in construction, including consideration of legal and contractual framework and the complex and interdisciplinary nature of the project environment. The analysis reveals that, despite numerous criticism, project and construction planning should be done using CPM scheduling. Main factors affecting successful planning are realistic estimation of the productivity of crews in the context of expected job‐management efficiency conditions, and inclusion of sufficient time buffers between dissimilar trades. CPM is found to be equally useful as a planning tool for linear or repetitive projects. The limitations of this technique are identified in terms of the defined planning functions in the engineering phase of capital projects. A broad model for management of the engineering phase in revenue‐generating projects is suggested.     

Construction management know-how for transnational projects

Characteristics of transnational projects are outlined and their environment reviewed with a view to highlighting those external variables that affect managerial functions in such projects. Reference is made to the published experiences on some macroprojects executed in various parts of the world. It is concluded that the know-how in this field is at best sketchy and unrelated to the actual managerial needs. Many of the present techniques and associated infrastructures are inadequate for handling transnational projects. Specifically, the techniques for the estimation of resources and costs, for the handling of information requirements and for financial transactions are substantially underdeveloped and unreliable.     

Regional water quality management for the Karun–Dez River basin, Iran

To achieve water quality goals in a river basin, a water quality management model (WQMM) has been developed through the geographic information system (GIS) approach and a mathematical water quality model. The developed model has been applied to the Karun and Dez Rivers, where water quality has decreased due to heavy pollutant loads from Khuzestan province cities and surrounding areas. Pollution sources, land use, geographic features and measured water quality data of the river basin were incorporated into the Arc‐View GIS database. With the database, the management model calculated management type and management cost for each management project in the river basin. Until now, river management policy for polluted rivers in Iran first penalizes pollution sources and then constructs treatment plants for the pollution sources whose wastewater is released untreated and for which the wastewater quality goal of the Iranian Department of Environment is not met. Different management projects with a time programme were proposed and they were compared with the results of the river quality without any management approach. It became clear that the results based on the management approach were much better than those for the unmanaged condition from the viewpoint of the achievement of water quality goals and cost optimization.     

Preparation,Characterization, and Mucoadhesive Properties of Chitosan-Coated Microspheres Encapsulated with Cyclosporine A

The aim of this study was to prepare and characterize chitosan-coated microspheres containing cyclosporine A (CyA). Microspheres encapsulated with CyA were prepared by solvent evaporation-emulsification methods. Microspheres were immersed in chitosan solution (0.5% w/w) to be coated. Morphology, mean size, and encapsulation efficiency of chitosan-coated microspheres were evaluated. To assess the mucoadhesive properties of this drug delivery system, the percent of mucin adsorption to the surface of coated microspheres was determined. Microspheres were spherical in shape. Encapsulation efficiency of different microsphere formulations varied from 78% to 92%. According to the mucin adsorption results, this particulate system showed suitable mucoadhesive properties. It can be concluded that surface modification of microspheres by chitosan coating would increase the prospects of their usefulness as oral drug delivery systems for CyA.     

VIRCON: Interactive System for Teaching Construction Management

The focus in this paper is on a system, developed by the writers, called VIRCON (short for VIRtual CONstruction), in which the traditional construction planning is combined with 3D∕4D models of the project. To facilitate current best practices with 3D∕4D models of the project, VIRCON has been implemented using object-oriented programming, client/server configuration, database management information, and CAD systems. The real innovation in the design of VIRCON is associated with the unique scheduling and simulation engine developed to integrate cost planning and scheduling and accommodate integrated cross-impact analysis. VIRCON has been validated by means of student group projects on a course where many of the project management techniques are being taught. The teaching approach conducted with the utilization of VIRCON has shown the way forward in creating a dynamic and interactive learning atmosphere. This paper also outlines the experience gained from teaching construction planning fundamentals by means of the VIRCON system.     

The excellent photocatalytic activity of novel Cs3PW12O40/WO3 composite toward the degradation of rhodamine B

In this paper, a simple one-pot thermal decomposition method was successfully used to synthesize a novel Cs₃PW₁₂O₄₀/WO₃ composite for the first time. The synthesized composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FTIR, diffuse reflectance spectroscopy (DRS) and N₂ adsorption-desorption techniques. The photocatalytic activity to degrade RhB molecules over Cs₃PW₁₂O₄₀/WO₃ composite was evaluated under xenon light irradiation. The results indicated the complete degradation of RhB molecules over Cs₃PW₁₂O₄₀/WO₃ composite after 30?min irradiation. However, the photocatalytic degradation of RhB over WO₃ and Cs₃PW₁₂O₄₀ after 80?min light irradiation are nearly 52%, and 68%, respectively. The enhanced photocatalytic activity of Cs₃PW₁₂O₄₀/WO₃ composite compared with WO₃, and Cs₃PW₁₂O₄₀ was ascribed to the strong interaction between WO₃ and Cs₃PW₁₂O₄₀, which effectively reduces the recombination of photogenerated electron-hole pairs. Based on experimental results, the possible mechanism of photocatalytic reactions on the Cs₃PW₁₂O₄₀/WO₃ composite photocatalyst was investigated, and the hydroxyl radical (OH) and superoxide radical (O₂^?) were determined as the main active species in the photocatalytic degradation of RhB over Cs₃PW₁₂O₄₀/WO₃ composite.     

Fabrication of Biogenic Silica Nanostructures from Sorghum bicolor Leaves for Food Industry Applications

Silicon - Due to the large production of sorghum, the generation of associated agricultural residues, which contain high contents of silica, is inevitable. Also, these agricultural residues are not...