Quantitative measurement of filament ruptures of a multi-filament AR-glass yarn embedded in concrete

This paper presents a new digital image analysis method for quantitative and online measurement of filament ruptures of a multi-filament AR-glass yarn embedded in concrete during pullout loading. The proposed method was developed based on an existing test method for determination of filament ruptures occurring during the loading called failure investigation using light transmitting (FILT) property test, which uses light transmitting property of AR-glass fibers. Artificial light is exposed on the glass filaments from one side of the specimen. On the opposite side, a charge-coupled device (CCD) camera with an optical microscope records the lighted filament cross-sections in the yarn. To detect filament ruptures during pullout loading, the light intensity time history of every individual filament of the yarn was investigated by a digital image analysis method. The number of broken filaments was also investigated by acoustic emission (AE) analysis simultaneously and the results were compared. Test results showed that the light transmitting property of AR-glass can be used to identify filament ruptures and it is possible to determine the failure of the filaments during pullout in the cross-section quantitatively by the improved FILT test.     

Mechanical performance of low cement reactive powder concrete (LCRPC)

The possibility of producing a reactive powder concrete (RPC) with low cement content was aimed in the scope of this study. Cement was replaced with class-C fly ash (FA) up to 60% for this purpose. Three different curing conditions (standard water curing, autoclave curing and steam curing) were applied to specimens. Two series of RPC composites were prepared with bauxite and granite aggregates. Mechanical properties such as compressive strength, splitting tensile strength, flexural strength and fracture energy of composites were investigated. Test results showed that, compressive strength of 200 MPa can be reached with low cement by using high-volume fly ash. Thermally treated specimens showed compressive strength beyond 250 MPa and high volume fly ash RPC have superior performance. Furthermore, compressive strength values reached up to 400 MPa with external pressure application during setting and hardening stages.     

Electrocatalytic Performances of Carbon Supported Metallophthalocyanine and Pt/Metallophthalocyanine Catalysts Towards Dioxygen Reduction in Acidic Medium

Electrocatalytic performances of phthalocyanines (Pcs) involving N-benzyl-4-phenyloxyacetamide moieties, dispersed on a high-surface area carbon substrate, Vulcan XC-72 (VC) and Nafion (Nf), towards oxygen reduction in acidic medium were determined and compared. The VC/Nf/CoPc(5) catalyst showed much higher catalytic activity than those of the other Pc(1–4)-based catalysts (H₂Pc 1, ZnPc 2, NiPc 3 and CuPc 4) and that of unsubstituted CoPc-based one. The comparison of the performance of VC/Nf/Pt-5 dual catalyst with that of VC/Nf/Pt one indicated that the former can be a good alternative to the latter as a cathode catalyst both in direct methanol and H₂/O₂ fuel cell applications.     

Microstructural, geochemical and geomechanical properties of caliche deposits from the Adana Basin, Turkey

The 1998 Ceyhan (Adana, Turkey) earthquake caused major damage to construction on caliche formations. Caliche (a heterogenous secondary calcium carbonate deposit formed in arid and semi-arid regions) is widespread in the Adana area. The paper distinguishes three types of caliche: massive, containing vegetation remains and containing gravel. The porosity, water absorption and unconfined compressive strength of these three groups of caliche were determined. The compressive strengths are low compared to caliches in other areas—an important consideration as Adana is the fourth largest city in Turkey.      

Synthesis and spectroelectrochemistry of new phthalocyanines with ester functionalities

Metal-free (H₂Pc) and metallophthalocyanines (MPc; M: Co, Zn) with four n-pentyl ester of thioglycolic acid groups have been synthesized by the esterification of the corresponding carboxylic acid derivatives with n-pentanol. The novel phthalocyanine compounds were characterized by elemental analyses, mass, FT-IR and UV-Vis spectral data. The aggregation investigations carried out in different concentrations and solvents indicate that ester substituted metal-free and metallo-phthalocyanine compounds have not shown any aggregation behavior in the concentration range of about 10⁻⁵ M. Electrochemical and in-situ spectroelectrochemical measurements give common MPc based redox behaviors which supported the proposed structure of the complexes. While CoPc gives both metal-based and ring-based redox processes, H₂Pc and ZnPc give only ring-based electron transfer processes. In-situ electrocolorimetric method was applied to investigate the color of the electro-generated anionic and cationic forms of the complexes.     

Effect of ambient temperature on Robertson-Berger-type erythemal dosimeters

To quantify the effect of ambient temperature on the voltage signal of Solar Light UV-Biometers, spectral response functions of two instruments were determined in the laboratory under various external temperature conditions. Despite the biometer's internal temperature stabilization, a temperature increase of 20 degrees C at the outside of an instrument's housing resulted in a reduction of the instrument's spectral response by as much as 10% in the UVB range and by as much as a factor of 2 in the UVA range, depending on the individual instrument and on its internal relative humidity. The significance of this effect for outdoor measurements is demonstrated by data from an intercomparison campaign of erythemal radiometers in Thessaloniki, Greece, organized by the Laboratory of Atmospheric Physics (Aristotle University of Thessaloniki), the Cooperation in Science and Technology (European Commission), and the World Meteorological Organization. On 16 September 1999, 12 of 16 Solar Light Biometers showed significant diurnal variation in their sensitivity (as much as 10% for some individual instruments), which can be explained through a heating of the instruments' housings due to direct solar radiation.     

Selection application of material to be used in hip prosthesis production with analytic hierarchy process

Metallic biomaterials used in making hip prosthesis are required to meet expectations in terms of fatigue strength, corrosion resistance, wear resistance, cost and biocompatibility. It is also desirable that the modulus of elasticity they possess is close to the level of the possible bone. Metallic biomaterials face the problem of ion release even though they meet the criteria mentioned above. As a result, the choice of metallic material to be preferred in the manufacture of hip prosthesis can be made by evaluating all these criteria among themselves and by the performances of biomaterials to be compared according to these criteria. In this study, firstly the criteria expected from the metals to be used as biomaterials have been determined. Expert opinions about the subject and criteria determined in accordance with the studies in the literature by using analytical hierarchy process have been graded according to each other. Afterwards, selection of the most appropriate material was ensured by making the order of importance according to the criteria of the candidate materials.