Effect of rock properties on the Los Angeles abrasion and impact test characteristics of the aggregates

Aggregate is the most fundamental and widely used component of construction. It is used as an unbound material which constitutes about 100% of the volume of base courses, 95 to 93% of the volume of asphalt and about 85 to 75% of the volume of Portland cement concrete. Aggregate is exposed to a number of physical and chemically degrading forces during processing, transporting, and construction. As the main load carrying component of unbound and bituminous and Portland cement concretes, the aggregate must be clean, hard, sound, durable, resistant to abrasion, uniform in quality and free of any detrimental quantities of soft, friable, thin, elongated or laminated pieces, disintegrated material, alkali or other deleterious substance. For assesing the abrasion resistance of aggregates, the most common method is the Los Angeles abrasion and impact test (LAAI) which determines the relative competence or resistance to abrasion of the aggregates.In this study, four limestones, four travertines, three crystalline marbles and one andesite were tested to evaluate the correlations between the LAAI values and the physical properties covering bulk density, Schmidt hardness, shore hardness, P-wave velocity and mechanical properties such as uniaxial compressive strength, point load index, and indirect tensile strength of rocks. Since these properties are of great importance as a source of aggregates, tests on the rock can give an indication of the strength of the aggregates.The above rock properties were determined through standard testing methods in order to investigate the correlation between LAAI and each rock property by using regression analysis. A simple equation predicting the LAAI value based on each rock property was suggested. From the statistical tests, rock properties were found to be significant in estimating the LAAI values of rocks.     

The fracture toughness of borides formed on boronized cold work tool steels

In this study, the fracture toughness of boride layers of two borided cold work tool steels have been investigated. Boriding was carried out in a salt bath consisting of borax, boric acid, ferro-silicon and aluminum. Boriding was performed at 850 and 950 °C for 2 to 7 h. The presence of boride phases were determined by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indenter. Increasing of boriding time and temperature leads to reduction of fracture toughness of borides. Metallographic examination showed that boride layer formed on cold work tool steels was compact and smooth.     

Interrelationships between P-V-T and flow behavior of linear and nonlinear hydrocarbons

The aim of this work is to determine the branching effect on the flow behavior of alkanes. For this purpose, the zero-shear viscosity, η₀, was analyzed in terms of the Simha-Somcynsky equation of state, SS-EOS, using the hole fraction, h = h(P, T) computed from it. For the analysis, η₀-data of the linear and three-branch alkanes measured in a wide range of temperature and pressure, were used. For the linear species, Utracki proposed a relation, viz. ln η₀ = a₀ + a₁/(h + a₂), where a₁ = 0.79 and a₂ = 0.07 are the universal parameters for linear hydrocarbons and their mixtures. In this work, this relation was found to be valid for the linear but not for the branched alkanes.     

Burkholderia multivorans SB6 Lipase as a Detergent Ingredient: Characterization and Stabilization

In this study, 265 bacterial isolates were collected from kitchen wastewater samples using Rhodamine B agar medium. Of these, 115 isolates were found to respond positively to the addition of commercial detergents. Using 16S rRNA sequence analysis, the isolate demonstrating the high stability towards commercial detergents was identified as Burkholderia multivorans. An SB6 lipase with a molecular mass of 70 kDa was purified from B. multivorans. The purified enzyme showed optimal activity at pH 9.0 and 40 °C and remained stable in the presence of various metal ions, surfactants, and oxidizing agents. The addition of boron compounds improved the pH stability and thermostability of the enzyme, which displayed stability against some commercial detergents; moreover, this stability increased when boron compounds were added to the incubation medium as stabilizers. These properties make SB6 lipase an ideal choice as an additive in detergent formulations.     

Magnetic properties and remanence analysis in permanently magnetic BaFe12O19 foams

In the present study, magnetic properties of barium ferrite foams were investigated. We especially examine the effects of porosity on interparticle interactions and remanence properties of these materials. It was observed that magnets become harder with porosity. On the other hand, saturation magnetization decreases slightly. Existence of porosities increases the strength of demagnetising-like interactions of neighboring particles.     

Effects of cavity disinfectants on bond strength of an etch-and-rinse adhesive to water- or ethanol-saturated sound and caries-affected dentin

Objective: To evaluate the effect of cavity disinfectants on the immediate microtensile bond strength (μTBS) of an etch-and-rinse adhesive to water- and ethanol-saturated sound and caries-affected dentin (CAD). Material and Methods: Thirty-six human molars were sectioned to expose 1/3 of the mid-coronal dentin surface. Sound (n = 18) and CAD (n = 18) specimens were divided into six groups each (n = 3): one positive control (sound), one negative control (CAD), and five experimental groups each. In the control group, dentin surfaces were bonded using an etch-and-rinse adhesive with a traditional water-wet bonding technique. In the experimental groups, ozone was applied before etching and chlorhexidine after etching. In the ethanol-wet bonding groups, acid-etched dentin surfaces were treated with ethanol. Following adhesive application and composite buildups, bonded specimens were sectioned to form sticks. Failure modes were analyzed using a stereomicroscope. Results: The water-wet bonded sound control group yielded the highest μTBS among all groups (p < 0.001). The lowest μTBS values were observed in the ozone groups (p < 0.05). The ethanol-wet bonded CAD group exhibited a higher μTBS than the water-wet bonded negative controls. Although compared to the positive control, chlorhexidine decreased the μTBS (p < 0.05), an increase with no significant difference was observed in the negative control (p > 0.05). Conclusions: The μTBS values of CAD were lower than those of sound dentin. Ethanol-wet bonding improved the μTBS of CAD. Ozone application reduced the μTBS in both sound and CAD; chlorhexidine improved the immediate μTBS after etching in CAD.     

Tribological Properties of SiC-Reinforced Basalt-Based Coatings

In the current study, the wear behaviour of basalt-based glass and glass–ceramic coatings was investigated. SiC-reinforced basalt-based powders were coated by an atmospheric plasma spray process and evaluated using the ball-on-disk wear test. X-ray diffraction analysis, scanning electron microscopy, and optical microscopy were employed for characterisation. The friction coefficients of the basalt-based glass and glass–ceramic coatings ranged from 0.38 to 0.55 and from 0.12 to 0.70, respectively, depending on the wear condition and SiC content. The wear test results show that SiC addition has a positive effect on the wear resistance of the glass and glass–ceramic coatings.     

RELATIONSHIP BETWEEN ORGANIC MATTER,SULPHUR AND PHOSPHATE CONTENTS IN UPPER CRETACEOUS MARINE CARBONATES (KARABOGAZ FORMATION,SE TURKEY): IMPLICATIONS FOR EARLY OIL GENERATION

In this paper, we discuss the relationship between the organic matter, sulphur and phosphate contents of Upper Cretaceous marine carbonates (Karabogaz Formation) in the Adiyaman Petroleum Province of SE Turkey. The results of organic geochemical analyses of core samples obtained from the Karabogaz Formation suggest that phosphate deposition occurred in settings where the water column was oxic to sub-oxic. However, the preservation of organic matter was favoured in anoxic environments. Moreover, the presence of sulphur (especially sulphur incorporated into kerogen) in organic matter-rich layers led to early oil generation. The results of stepwise py-gc analyses are consistent with a model in which, with increasing maturity, S-S and C-S bonds are the first to be eliminated from the macromolecular kerogen structure. Study of the maturity evolution of S-rich kerogen by laboratory pyrolysis implies that marginally mature and/or mature kerogen in the Karabogaz Formation, which may be classified as classic “Type II” kerogen, was most probably Type II/S at lower maturity stages. This enabled oil generation to occur at relatively shallow burial depths and relatively early stages of maturation. It is reasonable to conclude that Type II/S kerogen, overlooked in previous studies, was abundant in TOC-rich intervals in the Karabogaz Formation. Early generation (and expulsion) from Type II/S kerogen may have sourced the sulphur-rich oils in the Adiyaman area oilfields.