The frequency and predictors of helmet use among Iranian motorcyclists: A quantitative and qualitative study

Objective

This study examines the rate of helmet use and identifies barriers and facilitators of wearing helmets among Iranian motorcyclists. A mixed-method approach was used, including a structured seasonal survey with specific observations of a random sample of 6010 riders and qualitative methods that included 29 in-depth interviews and seven focus groups (n = 31).

Results

Only 10% of motorcyclists wear a standard helmet while riding. However, another 23% of motorcyclists used non-standard or partial helmets that covered only part of the head and do not prevent head trauma injuries effectively. We observed only 2 of 264 child passengers and 22 of 1951 adult passengers wearing helmets. Almost no one used protective pants or clothing made to be more visible in traffic. Themes emerged from qualitative interviews and were grouped into three main categories: (1) helmet characteristics; (2) social and cultural factors; and (3) personal and psychological factors.

Conclusion

Overall, the motorcyclists in our study believed that wearing a safety helmet protects them against serious injuries or death during a crash; however, only a small percentage of the motorcyclists used safety helmets. National intervention programs addressing motorcycle safety should aim to overcome barriers to and promote facilitators of helmet use, including providing inexpensive standard helmets, banning manufacturing/using unsafe partial or dummy helmets, as well as enforcing helmet use on a consistent basis.     

The effect of 3-(triethoxy silyl) propyl amine concentration on surface modification of multiwall carbon nanotubes

Abstract

The influence of 3-(triethoxy silyl) propyl amine (TESPA) concentration on Multi Wall Carbon Nanotubes (MWCNTs) modification, is experimentally investigated. The MWCNTs modification were performed by 150, 75 and 25 weight percent (wt.%) of TESPA with respect to MWCNTs weight and the properties of the prepared samples were compared with each other and pristine MWCNTs. The MWCNTs silylation has been confirmed by Fourier Transformation Infrared Spectroscopy due to O-H stretching absorption peak disappearing. The 75?wt.% silyl grafted MWCNTs with increasing at about 26.7% in mean value diameters size owns more uniform morphology among the samples based on Scanning Electron Microscopy images. Also, Thermo Gravimetric Analysis shows that this sample has higher thermal stability because of lower weight loss (9.97%) in coupling agent decomposition temperature range at about 119.5–480?°C. Furthermore, X-Ray Diffraction indicates that the mentioned sample has higher level of amorphous structure with 39% reduction in crystallite size in comparison with the pristine MWCNTs. So, the 75?wt.% of TESPA introduced as the optimal concentration for this type of MWCNTs modification.

• Highlights

• Introduction of silyl compounds as a proper coupling agent to modify the carbon nanotube surfaces

• Determination of optimal silyl compounds concentration to modify the carbon nanotube surface

• Cristallinity in XRD pattern can determine the success of CNTs grafted with silyl compounds

     

Thermocatalytic decomposition of methane over mesoporous Ni/xMgO·Al2O3 nanocatalysts

This paper describes a facile method to produce mesoporous nanostructure Ni/Al₂O₃, Ni/MgO, and Ni/xMgO.Al₂O₃ (x: MgO/Al₂O₃ molar ratio) catalysts prepared by “one-pot” evaporation-induced self-assembly (EISA) method with some modifications for investigating in the thermocatalytic decomposition of methane. Detailed characterizations of the material were performed with X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and N₂ adsorption/desorption, hydrogen temperature-programmed reduction (H₂-TPR), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed oxidation (TPO). The characterizations demonstrated that the synthesized catalysts with various MgO/Al₂O₃ molar ratios possessed mesoporous structure with the high BET area in the range of 216.79 to 31.74 m² g^?1. The effect of different surfactants and calcination temperatures on the characterizations and catalytic activity of the catalysts were also examined in details. The experimental results showed that the catalysts exhibited high catalytic potential in this process and the 55 wt.% Ni/2 MgO·Al₂O₃ catalyst calcined at 600^οC possessed an acceptable methane conversion (～60%) under the harsh reaction conditions (GHSV = 48000 (mL h^?1 g_cat^?1)).     

Synthesis,Characterization, Cytotoxicity and Detailed HSA Interaction of New Zinc(II) Complexes Containing Dithiocarbamate and Heterocyclic N-donor Ligands

[Zn(ph-dtc)(bpy)]Cl (1) and [Zn(ph-dtc)(phen)]Cl (2) (where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline and ph-dtc = phenylacetichydrazidedithiocarbamate) were synthesized and characterized by elemental analysis and spectroscopic methods (FT–IR, UV–Vis and ¹H NMR). Zn(II) complexes were examined in biological tests in vitro using MCF-7 breast cancer cell line. Both complexes showed significant cytotoxic activity against human breast cancer MCF-7 cells. The interaction of above compounds with Human Serum Albumin (HSA) was investigated by means of various spectroscopic (at pH ～ 7.4 in Tris–HCl buffer medium) and molecular docking methods. The fluorescence data showed that 1 and 2 quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constants (K_b) and the number of binding sites (n ～ 1) were calculated. The thermodynamic analysis suggested that hydrophobic interaction played major roles in the binding of 1 or 2 to HSA. The distance r between protein and the above-mentioned compounds was obtained according to fluorescence resonance energy transfer. The conformational changes of protein secondary structure in the presence of Zn(II) complexes were proven using UV–Vis absorption and circular dichroism techniques. Also, docking results confirmed the spectroscopic results.     

Elastic interactive buckling strength of corrugated steel shear wall under pure shear force

Different ways have been presented to prevent elastic buckling of steel shear walls. One of these solutions is corrugated shear wall. In this type of wall, shear buckling strength increases without increasing the thickness of the panel. Numerical modeling results indicate that, always, shear buckling strength of corrugated panels is more than the flat panels and with the right choice of the geometric parameters of corrugated panels; without increasing the thickness of the panel, we can improve buckling strength significantly. In the trapezoidal corrugated panels, reducing the width of the subpanels do not always increase buckling strength of the panel, but it changes the panel buckling shape from the local buckling mode to the global buckling. In addition, in panels, with the low width of the subpanels, elastic buckling does not happen in the subpanels. Comparing numerical analysis with the theoretical relations showed that the results of numerical analysis with the relations that include local buckling, global buckling, and shear yielding stress, have a better approximation and in another word, interaction buckling is the combination of the local buckling, global buckling, and shear yielding stress.     

Project Delivery System Selection under Uncertainty: Multicriteria Multilevel Decision Aid Model

Selecting an optimal project delivery system is a critical task that owners should do to ensure project success. This selection is a complex decision-making process. The complexity arises from the uncertain or not well-defined parameters and/or the multiple criteria structure of such decisions. In this study, a decision aid model using the analytical hierarchy process (AHP) coupled with rough approximation concepts is developed to assist the owners. The selection criteria are determined by studying a number of benchmarks. The model ranks the alternative delivery systems by considering both benchmark results and owner’s opinion. In interval AHP, an optimization procedure is performed via obtaining the upper and the lower linear programming models to determine the interval priorities for alternative project delivery systems. In cases having incomparable alternatives, which is the most likely case in uncertain decision making, the model uses rough set-based measures to reduce the number of decision criteria to a subset, which is able to fully rank the alternatives. To illustrate the applicability and usefulness of this methodology, a real world case study will be demonstrated.     

Foreground–background separation technique for crack detection

Current level‐2 condition assessment methods for critical infrastructure assets mostly rely on human visual investigation of visible damages and patterns at the structure surface, which can be a costly, time‐consuming, and subjective exercise in reality. In this article, a novel method for crack detection is proposed via salient structure extraction from textured background. This method first extracts strong edges and distinguishes them from strong textures in a local neighborhood. Then, the spatial distribution of texture features is estimated to detect cracks as salient structures that are not widely spread across the whole image. The outputs from these two key steps are fused to calculate the final structure saliency map for generation of the crack masks. This method was validated on a data set with 704 images and the outcome revealed an average f‐measure of 75% in detecting the concrete cracks that is significantly higher than two other baseline methods.     

A highly active and stable chromium free iron based catalyst for H2 purification in high temperature water gas shift reaction

In this work mesoporous nanocrystalline chromium free Fe–Al–Ni catalysts with various Fe/Al and Fe/Ni ratios were prepared by coprecipitation method for high temperature water gas shift reaction. The prepared catalysts were characterized using X-ray diffraction (XRD), N₂ adsorption (BET), temperature-programmed reduction (TPR) and transmission electron microscopy (TEM) techniques. The catalytic results revealed that the catalyst with Fe/Al = 10 and Fe/Ni = 5 weight ratios exhibited the highest catalytic activity among the prepared catalysts and the commercial chromium containing one. This catalyst possessed a high surface area of 177.4 m² g⁻¹ with an average pore size of 4.3 nm with a high stability during 20 h time on stream. Furthermore, the effect of calcination temperature, GHSV and steam/gas ratio on the structural properties and catalytic performance of the catalyst with the highest activity was investigated.