Effect of chemically modified waste rubber powder as a filler in natural rubber vulcanizates

Waste rubber powder (RP) was subjected to chemical modification by using different concentrations of oxidizing agents such as nitric acid and 30% hydrogen peroxide solution. This treatment leads to introducing some functional groups onto the surface of RP. The chemically modified RP was incorporated in natural rubber mixes either alone or in combination with carbon black (HAF). The physicomechanical properties of NR vulcanizates obtained were studied and compared to NR vulcanizates filled with untreated RP. It was found that the chemically modified RP improves tensile strength and aging resistance of NR vulcanizates compared with untreated RP. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 30–36, 2004     

Motorcycle-related injuries in the United Arab Emirates

Objectives

To study the anatomical distribution, severity, outcome, and age by nationality of hospitalized motorcycle-related injured patients in Al-Ain, United Arab Emirates so as to improve preventive measures.

Methods

All motorcycle riders involved in a road traffic collision and admitted to Al-Ain Hospital for more than 24 h or who died in hospital after arrival were studied. Patient data were retrieved from Al-Ain Hospital Trauma Registry. Data had been prospectively collected during four and half years (March 2003–October 2007). Demography of patients, Glasgow Coma Scale (GCS), Injury Severity Score (ISS), Hospital stay, mortality, nationality, time, day of week, and month of occurrence were analyzed.

Results

There were 95 patients (93 males). Mean (SD) age was 29.8 (11.5) years. 35% were United Arab Emirates (UAE) nationals. Upper limbs were most frequently involved (54%) followed by lower limbs (48%), head (41%), and face (30%). On arrival at hospital, median (range) ISS was 4.5 (1–36) and median (range) GCS was 15 (3–15). Mean (range) hospital stay was 8.8 (1–79) days. 14 patients (15%) were admitted to the Intensive Care Unit. In-hospital mortality was 6%. UAE national victims were significantly younger and had more abdominal injuries than expatriates, who had lower limb injuries.

Conclusions

The most common mechanism of motorcycle crashes was hitting a moving vehicle. Young UAE national motorcyclists are at a higher risk of being injured compared with non UAE nationals. This may be due to risk-taking behavior of young motorcyclists who are mainly riding for leisure. Extremities were the most common injured body region. Severe head injury was the main cause of death. This signifies the need for effective application of motorcycle helmet law in the UAE along with other preventive measures that might include increasing the licensing age.     

Does wearing helmets reduce motorcycle-related death? A global evaluation

Background

The high risk of injury and death of motorcycle riders is a major global health problem. This study aimed to evaluate the effect of helmet wearing on motorcycle riders’ death rates on a global level.

Methods

Data for motorcycle riders were collected from 70 countries. These data included motorcycle-related death rates per 100 000 population, helmet non-usage percentage, Gross National Income per capita (GNI), number of registered motorized 2–3 wheelers, the effectiveness of law enforcement in each country, and whether there was standards for helmets use or not. Correlations between studied variables were done using Pearson correlation. Multiple linear regression models were used to define factors affecting motorcycle-related death rates.

Results

The correlation between motorcycle-related death rate and helmet non-usage, was almost significant (p = 0.056, r = 0.28). Helmet non-usage percentage was significantly correlated with GNI (p < 0.0001, r = −0.61) and effectiveness of the law (p < 0.0001, r = −0.73). A multiple linear regression model which was highly significant (adjusted R-squared = 0.3, F = 6.69, p < 0.001) has shown that helmet non-usage percentage (p = 0.003), motorcycle per person ratio (p = 0.01) and the presence of helmet standards (p = 0.05) were positively associated with motorcycle-related death rates. A simple linear regression model between helmet usage and road traffic death rate has shown that for each 10% increase in helmet usage, one life per 1 000 000 inhabitants can be saved per year.

Conclusion

Helmet non-usage percentage was the most significant factor affecting motorcyclists’ death rate. Wearing a motorcycle helmet reduces the risk of death from a motorcycle crash. Enforcement of motorcycle helmet laws should be effectively supported by motorcycle safety programs.     

Nanosilicon dioxide/o-phenylenediamine hybrid composite as a modifier for steel paints

Different amounts of the hybrid composite nano SiO₂/o-phenylenediamine were added to a typical paint being used for protecting steel against corrosion to increase its protection efficiency. The nano features of the composite were confirmed by different electron microscopic investigations. It was found that the protection efficiency of the paint increased significantly as well as its adhesion to the steel surface increased. These conclusions had been inferred from both potentiodynamic polarization and electrochemical impedance spectroscopy techniques. To confirm the previous concept salt spray test and adhesion force measurements were carried out. The results were interpreted in terms of the filling properties of nano SiO₂ and adsorption/hardening power of o-phenylenediamine.     

Extraction of Lanthanum and Samarium from Nitrate Medium by some Commercial Organophosphorus Extractants

Abstract

The extraction of lanthanum(III) and samarium(III) from nitrate solutions by some phosphine oxide compounds (Cyanex 921, Cyanex 923, and Cyanex 925) in kerosene was investigated. The influence of the different factors affecting the extraction was studied in detail. The extraction of these metals using the above extractants was compared and the sequence of extraction was found to be Cyanex 921>Cyanex 923?Cyanex 925. The stripping percent of La(III) and Sm(III) by 0.75 M HNO₃ from the loaded organic phase after two stages were 72% and 5.2%, respectively, which could enable a good separation between these two lanthanides.     

岩石动力学中离散元程序处理波幅的新方法

顺应日益更新的计算机硬件及其外部设施，结合离散元程序UDEC，MATLAB和EXCEL，提出了一种在UDEC中全面处理各节点或单元中心波幅的数据处理新方法．该方法涉及修改UDEC源程序以扩展时间历程及表格上限、应用UDEC中的内嵌语言FISH在建模件中自动记录波的时间历程以及在MATLAB中处理各节点或单元中心波的幅值．给出了该方法在岩石动力学中波动问题研究的应用实例，结果表明：该方法优点多，在岩石动力学研究中具有较高的实用价值。     

Experimental study on prediction model for maximum rebound ratio

The proposed prediction model for estimating the maximum rebound ratio was applied to a field explosion test, Mandai test in Singapore. The estimated possible maximum peak particle velocities(PPVs) were compared with the field records. Three of the four available field-recorded PPVs lie exactly below the estimated possible maximum values as expected, while the fourth available field-recorded PPV lies close to and a bit higher than the estimated maximum possible PPV. The comparison results show that the predicted PPVs from the proposed prediction model for the maximum rebound ratio match the field-recorded PPVs better than those from two empirical formulae. The very good agreement between the estimated and field-recorded values validates the proposed prediction model for estimating PPV in a rock mass with a set of joints due to application of a two dimensional compressional wave at the boundary of a tunnel or a borehole.     

Rock dynamics research related to cavern development for Ammunition storage

Researches on rock dynamics related to a cavern development project for ammunition storage in Singapore have been carried out. The researches include the study of dynamic properties of rock material (strength, modulus, constitutive relations), dynamic normal and shear properties of rock joints, shock wave propagation across joints and through the rock mass, and dynamic response of the rock mass and structures in rock using the discrete element method. The results obtained from the research works provide the necessary input to the design and construction of the cavern project.     

On the electrochemical behaviour of tungsten: the formation and dissolution of tungsten oxide in sulphuric acid solutions

The formation and dissolution of the anodic oxide film of tungsten were investigated in sulphuric acid solution of different concentrations. The dissolution process was found to follow a first order mechanism under different conditions. It seemed that, in highly diluted solutions, the hydrate formation is favoured, whereas in concentrated solutions, the process takes place via the formation of WO₂²⁺. The rate of dissolution was found to increase by increasing the initial current density of formation.     

Book review

HANDBOOK OF GROUNDWATER DEVELOPMENT by Roscoe Moss Company, LA John Wiley & Sons, New York, 1990, 493 pp.