Modulus of elasticity of substandard and normal concretes

Modulus of elasticity is an important parameter used for the structural assessment and retrofitting of concrete structures. In this study, an experimental investigation on the modulus of elasticity of concrete was carried out, the results of which is presented. 60 mixtures were prepared, in which the effects of water/cement ratio, maximum size of the aggregate, aggregate type, and fly ash content were investigated. In order to obtain very low quality concrete, the water/cement ratios were increased to as high as 2.2. Modulus of elasticity of the concretes was obtained according to ASTM C469. Compressive strength and ultrasound pulse velocities of the concretes were also recorded. The experimentally obtained modulus of elasticity values were compared with those calculated by using prediction models given in a selection of codes of practice. Dynamic moduli of elasticity of the concretes were also obtained.     

Efficacy of lodoxamide 0.1% versus N-acetyl aspartyl glutamic acid 6% ophthalmic solutions in patients with vernal keratoconjunctivitis

The purpose of this study was to investigate environmental lead exposure in the general Taiwanese population. A total of 8828 Taiwanese adults selected by a multistage sampling method were investigated. Characteristics of the participants were ascertained by questionnaire and 10 ml venous blood was drawn by public health nurses. The blood specimens were distributed to six laboratories for blood lead level (BLL) measurement. A quality control program was applied during the analysis of the BLLs in order to improve precision and accuracy. The arithmetic mean BLL of the 8828 Taiwanese adults was 7.70 +/- 5.23 micrograms/dl, with a maximal level of 69.1 micrograms/dl. The median was 6.5 micrograms/dl and the 90th percentile was 14.0 micrograms/dl. After logarithmic transformation, the geometric mean was 1.84 +/- 0.67 microgram/dl. This study also found that elevated BLLs were associated with certain personal characteristics, i.e., gender, ethnic group, and education level; life-style factors, such as smoking, alcohol consumption, Chinese herbal drug consumption, milk consumption, and sources of drinking water; residential location, i.e., level of urbanization; and occupational history of lead exposure. However, age, floor level of residence, distance from house to road, and betel nut consumption were not associated with elevated BLLs. These results showed that BLLs in the Taiwanese population were not higher than those in developed and developing countries. Most of the influencing factors were also found in other studies; however, local factors such as ethnic group, Chinese herbal drug consumption, and sources of drinking water are important considerations in Taiwan when examining ways to prevent overexposure to lead in the general population.     

Long‐term oropharyngeal colonization by C. albicans in children with cystic fibrosis

This longitudinal prospective study aimed to determine the prevalence of oropharyngeal colonization by C. albicans in children with cystic fibrosis (CF), and observe the continuity of candidal colonization and the changes in production of virulence factors, susceptibility to antifungal agents and RAPD patterns of the isolates. Thirty‐seven children with CF were followed‐up for oropharyngeal C. albicans colonization for 18 months. The colonization rate was detected in 54%. All isolates were susceptible to amphotericin B, but those isolated from one patient were resistant to fluconazole. Biofilm production, secretory acid proteinase, phospholipase and esterase activity rates were 30%, 60%, 75% and 80%, respectively. RAPD analysis with the primers OPE‐03 and OPE‐18 was performed for genotyping. RAPD patterns of the strains isolated from the same patient were related to each other, whereas they were not related with other strains isolated from different patients. Two C. albicans strains isolated from the same patient were found to be unrelated to one another. As a result, long‐lasting colonization of the oropharyngeal mucosa of children with CF by endogenous C. albicans isolates having the same RAPD pattern was demonstrated. Colonization prevalance and development of resistance to antifungal agents and the increased production of virulence factors were not correlated. Copyright © 2013 John Wiley & Sons, Ltd.     

Transient isotopic labeling studies using12CH4/13CH4 over alkali-promoted molybdate catalysts in the oxidative coupling of methane

The methane coupling reaction was investigated over MnMoO₄ and alkali (Li, Na, K)-promoted MnMoO₄ at 700°C using¹²CH₄/¹³CH₄ transient isotopic labeling experiments under steady-state reaction conditions. The variations observed in the surface residence times of CH₄, CO, and CO₂, ethane and ethylene were used to help explain selectivity differences previously reported in the oxidative coupling of methane over alkali-promoted molybdate catalysts.     

Cost assessment of concrete and steel types for office buildings: An exploratory study

This paper presents a set of regression models which incorporates concrete and steel types in modeling the costs of office buildings. To these ends, three typical office buildings with seven and 15 stories have been designed by the help of a commercial software taking into account the Turkish practice. In each project C-16, C-20, C-25, C-30 and C-35 concrete classes and S-220 and S-420 steel types were used for dimensioning purposes. Rough construction costs were then calculated for different combinations of concrete classes and steel types. The findings of the study revealed that column dimensions decrease following an increase in a particular concrete class. However, this decrease stops after C-30. Furthermore, an average cost difference of 16% was observed between the steel types S-220 and S-420.     

Carbon nanotube-DNA nanoarchitectures and electronic functionality

Biological molecules such as deoxyribonucleic acid (DNA) possess inherent recognition and self-assembly capabilities, and are attractive templates for constructing functional hierarchical material structures as building blocks for nanoelectronics. Here we report the assembly and electronic functionality of nanoarchitectures based on conjugates of single-walled carbon nanotubes (SWNTs) functionalized with carboxylic groups and single-stranded DNA (ssDNA) sequences possessing terminal amino groups on both ends, hybridized together through amide linkages by adopting a straightforward synthetic route. Morphological and chemical-functional characterization of the nanoarchitectures are investigated using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Electrical measurements (I-V characterization) of the nanoarchitectures demonstrate negative differential resistance in the presence of SWNT/ssDNA interfaces, which indicates a biomimetic route to fabricating resonant tunneling diodes. I-V characterization on platinum-metallized SWNT-ssDNA nanoarchitectures via salt reduction indicates modulation of their electrical properties, with effects ranging from those of a resonant tunneling diode to a resistor, depending on the amount of metallization. Electron transport through the nanoarchitectures has been analyzed by density functional theory calculations. Our studies illustrate the great promise of biomimetic assembly of functional nanosystems based on biotemplated materials and present new avenues toward exciting future opportunities in nanoelectronics and nanobiotechnology.     

Removal of copper ions from aqueous solutions by hazelnut shell

There is a great potential of woody hazelnut shell to use in some applications. Sorption studies are one of these. For this reason in this paper, batch adsorption of Cu(2+) ions onto hazelnut shells was studied. The capacity of the adsorption for the removal of copper ions from aqueous solution was investigated under different conditions such as solution contact time (1-360 min), particle size (0-75, 75-150 and 150-200 microm), temperature of solution (25-60 degrees ) and solution pH (3-7). Moreover, zeta potential of particles at different initial pHs (2-10) was measured. The equilibrium data were processed according to Langmuir and Freundlich's models and higher adsorption capacity values towards Cu(2+) ions were shown. The adsorption kinetics was investigated and the best fit was achieved by a second-order equation.     

Supercapacitors based on pillared graphene nanostructures

We describe the fabrication of highly conductive and large-area three dimensional pillared graphene nanostructure (PGN) films from assembly of vertically aligned CNT pillars on flexible copper foils for applications in electric double layer capacitors (EDLC). The PGN films synthesized via a one-step chemical vapor deposition process on flexible copper foils exhibit high conductivity with sheet resistance as low as 1.6 ohms per square and possessing high mechanical flexibility. Raman spectroscopy indicates the presence of multi walled carbon nanotubes (MWCNT) and their morphology can be controlled by the growth conditions. It was discovered that nitric acid treatment can significantly increase the specific capacitance of the devices. EDLC devices based on PGN electrodes (surface area of 565 m2/g) demonstrate enhanced performance with specific capacitance value as high as 330 F/g extracted from the current density-voltage (CV) measurements and energy density value of 45.8 Wh/kg. The hybrid graphene-CNT nanostructures are attractive for applications including supercapacitors, fuel cells and batteries.     

Formation of chromium nitride layers on AISI 1010 steel by nitro-chromizing treatment

In this study, chromium nitride coating was realized on AISI 1010 steels by nitro-chromizing treatment. Steel samples were tufftrided at 575 °C for 2 h in the first step of the coating process, and then chromized by pack method in the powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000 °C for 1-4 h. Samples were characterized by scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy, X-ray diffraction (XRD) analysis and Vickers micro-hardness tests. Coating layer formed on the steel samples is smooth and compact and well bonded to the steel matrix. The thickness of chromium nitride layer formed on the steel samples ranged from 5.16±1.48 to 13.45±1.73 μm, depending on the treatment time. The average micro-hardness value of the layer was 1789±59 HV_0.05. The layer consisted of Cr₂N and (Cr,Fe)₂N_(1−x) phases, according to XRD. EDS results showed that coating layer includes chromium and nitrogen.     

Cross-cultural differences in driving skills: a comparison of six countries

The first aim of the present study was to investigate the applicability of the two-factor structure (perceptual-motor skills by 11 items, e.g., "fluent driving"; safety skills by 9 items, e.g., "conforming to the speed limits") of the Driver Skill Inventory (DSI) among British, Dutch, Finnish, Greek, Iranian, and Turkish drivers. It was also hypothesized that the combination of self reported high ratings of perceptual-motor skills and low ratings of safety skills creates a serious risk for dangerous driving and road accident involvement. The second aim of this study was, therefore, to investigate this asymmetric relationship between perceptual-motor and safety skills in traffic penalties and accident involvement. Two hundred and forty two drivers were chosen from each of the six countries, matched for age and sex. The results of exploratory factor analyses together with target rotation showed that the two-factor structure of DSI found in "safe" Northern and Western European countries were highly congruent. However, the safety skills factor of DSI in Greece, Iran, and Turkey was relatively incongruent in spite of high factor similarity found in perceptual-motor skills. The asymmetric relationship between perceptual-motor and safety skills on traffic penalties was found in Finland and Turkey. A negative relationship between safety skills and the number of accidents was found both in Greece and Iran while a positive relationship between perceptual-motor skills and the number of accidents was found only in Iran.