Dynamically vulcanized polypropylene/ethylene‐propylene diene monomer/organoclay nanocomposites: Effect of mixing sequence on structural,rheological, and mechanical properties

Dynamically vulcanized thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP), ethylene‐propylene diene monomer (EPDM) and cloisite 15A were prepared via direct melt mixing in a co‐rotating twin‐screw extruder. The mixing process was carried out with optimized processing parameters (barrel temperature = 180°C; screw speed = 150 rpm; and feeding rate = 0.2 kg/hr). The formulation used to prepare the nanocomposites was fixed to 75/20/5 (PP/EPDM/Cloisite^©15A), expressed in mass fraction. Effect of mixing sequence on the properties of vulcanized and unvulcanized (TPE) nanocomposites prepared under similar conditions was investigated using X‐ray diffraction (XRD) and a tensile testing machine. Results showed that the sequence of mixing does affect the properties of final TPE nanocomposites. Accordingly, nanocomposite samples prepared through mixing the preblended PP/clay masterbatch with EPDM phase, show better clay dispersion within the polymer matrix. J. VINYL ADDIT. TECHNOL., 22:320–325, 2016. © 2014 Society of Plastics Engineers     

Mapping neighbourhood outdoor activities: space,time, gender and age

This paper investigates spatial, temporal, age and gender patterns of outdoor social activities in urban neighbourhoods and their correlation with properties of urban form. Informed by theories and mapping techniques in urban sociology, urban design and behavioural research, the paper develops a methodology for mapping outdoor social activities and applies it to four case studies in London and Berlin. Findings demonstrate how different types of activities are spatially distributed, reflecting socio-spatial characteristics of the given neighbourhood. The paper elaborates the contribution of the research to ongoing debates such as gendered space and age-friendly communities and suggests methodological improvements for future research.     

Horizontal bracing to enhance progressive collapse resistance of steel moment frames

In this paper, the effect of horizontal bracing on enhancing the resistance of steel moment frames against progressive collapse is investigated. Previously designed 6 bay by 3 bay 18‐story steel frame prototype building with 6 m bay span (namely, unbraced frame), which was susceptible to progressive collapse, is retrofitted by four types of horizontal bracing systems on the perimeter of the topmost story and analyzed using 3D nonlinear dynamic method. Six different cross‐sections for each bracing system type are considered, and the capacity curves for each model are obtained. Three column removal circumstances, namely, Edge Short Column, First Edge Long Column, and Edge Long Column are considered in this paper. The results imply that horizontal bracing would increase the resistance of moment frames against progressive collapse. However, one of the bracing types in which axial compressive force is created in braces is not appropriate for retrofitting.     

Durability assessment of Gerdoi and red travertines from Azarshahr,East Azerbaijan province,Iran

Bulletin of Engineering Geology and the Environment - Durability is the most important characteristic of stones in sustainable architecture. Salt crystallization has been known to damage porous...     

Anisotropy in Mechanical Properties and Corrosion of X-52 Pipeline Steel at Different Pipe Angles

Protection of Metals and Physical Chemistry of Surfaces - Non-uniform corrosion and cracking could occur at different pipe angles (different clocks) on oil and gas transmission pipelines. While...     

Recent Developments in Predicting Impact and Shock Sensitivities of Energetic Materials （英）

Empirical, quantum mechanical and artificial neural network methods are three usual methods in recent years that were used to predict sensitivity of different classes of high explosives. Some recent developments in predicting sensitivity by various methods are reviewed and discussed for various classes of energetic materials.     

Seismic microzonation and building vulnerability assessment based on site characteristic and geotechnical parameters by use of Fuzzy-AHP model (a case study for Kermanshah city)

ABSTRACT

On 12th November 2017, an earthquake with a magnitude of 7.3 Richter scale in the town of Sarpol-e Zahab took place that caused lots of human casualties and devastation. After the incident, issues related to the probability of an earthquake with equal intensity and extents of similar building destruction were raised in Kermanshah city. Therefore, a seismic microzonation map of Kermanshah city has been prepared based on the geotechnical, geological, and geophysical data, and the data were analysed using Fuzzy analytic hierarchy process (AHP). In the next step, the vulnerability analysis of city buildings was carried out based on the ground-shaking map, vulnerability curves, and statistical data regarding the buildings. The results of the vulnerability rate of residential buildings indicate that 80% of residential buildings would be exposed to vulnerability from low to moderate. However, other buildings would suffer 2% fully destruction (D1), 7% very high destruction (D2) and 11% high destruction (D3), respectively. Finally, according to the obtained results, the proposed model is verified with the help of the data and observations from the Sarpol-e Zahab earthquake, which reveals that the model is in good agreement with the actual earthquake data.     

Effect of light intensity and frequency of flashing light from blue light emitting diodes on astaxanthin production by Haematococcus pluvialis

Flashing light from blue light emitting diodes is an effective method for the reduction of energy consumption in the bioproduction of astaxanthin by Haematococcus pluvialis. We investigated the effects of light intensity and frequency on the final astaxanthin concentration in bioproduction by H. pluvialis grown mixotrophically. The final astaxanthin concentration under illumination with flashing light, with frequencies ranging from 25 to 200 Hz, was dependent on the light intensity and on the duty cycle and was equivalent, or higher, in comparison with that under illumination with continuous light at the same incident intensity. The light intensity determined the maximum attainable concentration of astaxanthin under continuous illumination. Under illumination with flashing light, the ratio of the final astaxanthin concentration to the maximum concentration at a specific light intensity was correlated to the duty cycle in the frequency range from 25 to 200 Hz. The effect of lower frequencies on enhanced astaxanthin production under flashing light was also studied; at levels as low as 1 Hz, higher final astaxanthin concentrations were observed under flashing light compared to concentrations attained under continuous light.     

Comparing the Effects of Microwave and Conventional Heating Methods on the Evaporation Rate and Quality Attributes of Pomegranate (<Emphasis Type="Italic">Punica granatum</Emphasis> L.) Juice Concentrate

Pomegranate juice was concentrated by conventional heating and microwave heating at different operational pressures (12, 38.5, and 100 kPa), and their effects on evaporation rate and quality attributes of concentrated juice were investigated. The final juice concentration of 40° Brix was achieved in 140, 127, and 109 min at 100, 38.5, and 12 kPa, respectively, by using conventional heating. Applying microwave energy decreased required times to 118, 95, and 75 min. The changes in color, anthocyanin content, and antioxidant capacity during concentration processes were investigated. L*, a*, and b* parameters were measured to estimate the intensity of color loss. All Hunter color parameters decreased with time. Results showed that the degradation of color, anthocyanins, and antioxidant activity were more important in conventional heating compared to microwave heating method. Degradation rates increases by increasing process pressure. A first-order kinetics model was applied to modeling changes in total solid content, anthocyanin content, and antioxidant capacity.