Effect of Polymethyl Methacrylate (PMMA) Powder to Liquid Monomer (P/L) Ratio and Powder Molecular Weight on the Properties of PMMA Cement

The present study investigated the effect of PMMA powder to liquid monomer (P/L) ratio and molecular weight of PMMA powder on the properties of PMMA cement. Two types of PMMA powder (Mw: 120,000 and 350,000) were prepared with different P/L ratios (based on wt/wt ratios); 0.75:1, 1:1, 1.25:1, and 1.5:1. Characterization of PMMA powders, handling characteristics and flexural properties of cured PMMA samples were investigated. In conclusion, low P/L ratio and high molecular weight of PMMA powders are desirable to produce PMMA cement with good handling properties and high flexural properties.     

Acetanilide-loaded injectable hydrogels with enhanced bioactivity and biocompatibility for potential treatment of periodontitis

Chronic periodontitis poses long-term challenges in dentistry, requiring the development of innovative dental composites with biocompatibility, bone regeneration, and antibacterial properties. This study focuses on synthesis of novel injectable thermoresponsive hydrogels composed of chitosan, sodium bicarbonate, bioactive glass (20 and 40% w/w), and acetanilide drug (0.3 and 0.6% w/w). These hydrogels exhibit a sol–gel transition at 37°C, addressing periodontal challenges with reduced gelation time. The smooth flow characteristic was evaluated through 17-22 gauge syringe needles at low temperature. Rheological studies demonstrated pseudoplastic behavior, with viscosity decreasing as shear rate increases. Fourier transform infrared and x-ray diffraction analysis confirmed the bioactivity of hydrogels, forming a bone-like apatite layer in simulated body fluid. The drug-loaded hydrogels demonstrated promising in vitro antibacterial properties against dental pathogens, specifically Staphylococcus aureus and Pseudomonas aeruginosa. Drug dissolution analysis revealed relatively high release rate at 37°C, highlighting its role in rapidly eliminating bacterial colonies at the target site, while the subsequent sustained release contributes to the prevention of infection recurrence. Finally, biocompatibility was assessed with fibroblast, where the cells were observed anchoring into the polymeric chains of hydrogel through extended filopodia.     

Nanoindentation Creep,Nano-Impact,and Thermal Properties of Multiwall Carbon Nanotubes–Polypropylene Nanocomposites Prepared via Melt Blending

Morphological analysis of the nanocomposites showed that multi-wall carbon nanotubes were uniformly distributed in polypropylene. Nanoindentation creep and nano-impact tests were carried out. Several equations/models were used to analyze creep data. From creep test, hardness of the nanocomposites increased by 18 and 36% for C150P and C70P, respectively, compared to polypropylene, whereas elasticity also increased by 20 and 34%. From nano-impact test, hardness of the nanocomposites was also higher than that of neat polypropylene. However, hardness (dynamic/impact) values were slightly higher than the (quasi-static) hardness resulted from creep test. In addition, degree of crystallinity of nanocomposites also increased by 12.6 and 14.3%.     

Energy poverty in rural Bangladesh

Energy poverty is a well-established concept among energy and development specialists. International development organizations frequently cite energy-poverty alleviation as a necessary condition to reduce income poverty. Several approaches used to measure energy poverty over the past 20 years have defined the energy poverty line as the minimum quantity of physical energy needed to perform such basic tasks as cooking and lighting. This paper uses a demand-based approach to define the energy poverty line as the threshold point at which energy consumption begins to rise with increases in household income. At or below this threshold point, households consume a bare minimum level of energy and should be considered energy poor. This approach was applied using cross-sectional data from a comprehensive 2004 household survey representative of rural Bangladesh. The findings suggest that some 58 percent of rural households in Bangladesh are energy poor, versus 45 percent that are income poor. The findings also suggest that policies to support rural electrification and greater use of improved biomass stoves might play a significant role in reducing energy poverty.     

The solar desalination plant in Abu Dhabi: 13 years of performance and operation history

The Abu Dhabi solar desalination plant started operation in September 1984 and is still operating until now. The plant was designed as a pilot unit for the evaluation of the technical economic feasibility of such plants for supplying fresh water to remote arid coastal areas of the UAE. The aim was to evaluate the long-term system performance and reliability and determine the optimal operating strategy and maintenance schedule. The plant consists of three subsystems: the solar collector field, the heat accumulator and the seawater evaporator. The solar collector field and the heat accumulator has experienced only a small amount of performance degradation, however, the evaporator have suffered from about 25 percent degradation in performance and is currently in need of an acid and demister cleanings to bring its performance to its original level.     

THE EFFICIENCY CHALLENGES OF RESOURCE DISCOVERY IN GRID ENVIRONMENTS

Resource discovery is one of the most important services that significantly affects the efficiency of grid computing systems. The inherent dynamic and large-scale characteristics of grid environments make their resource discovery a challenging task. In recent years, different approaches have been proposed for resource discovery, attempting to tackle the challenges of grid environments and improve the efficiency. Being aware of these challenges and approaches is worthwhile in order to choose an appropriate approach according to the application in different organizations. This study reviews the most important factors that should be considered and challenges to be tackled in order to develop an efficient grid resource discovery system.     

Femtosecond Ti: Sa ultra short-pulse laser irradiation effects on the properties and morphology of the zirconia surface after ageing

Femtosecond pulses from a Ti:Sapphire laser were used to irradiate specimens of yttria-stabilised (35% mol) tetragonal zirconia (Y-TZP) with the purpose of studying the effects of the irradiations on their surface properties and morphology after ageing. Zirconia disks were divided into eight groups (n = 32) according to their surface treatment and subsequent ageing: Control: no treatment; sandblasting: Al₂O₃ sandblasting 50 μm; and ultrashort laser pulses irradiation with 25 μJ pulses, considering two different scanning steps based on the width between two grooves. These groups were duplicated and submitted to ageing. The surfaces were analysed using scanning electron microscopy (SEM), and X-ray diffraction. A finite element analysis, a biaxial flexure test, as well as fractographic and Weibull analyses, were performed. The strengths of the disks were statistically different for the treatment factor, and the principal stresses seemed to be concentrated at the centre of the specimens, as predicted by the computer simulations. Ageing decreased the strengths for all groups and increased the Weibull modulus for the laser group with the 40 μm-width between two grooves. The sandblasting group presented the highest monoclinic phase peak. Although the most significant strength was found within the sandblasting group, the phase transformation was favourable to the laser groups. The Weibull modulus was higher for the laser group with the 60 μm-width between two grooves, confirming the highest homogeneity of its failure distribution. Regardless of the surface treatment, strength was decreased with ageing in all groups. The femtosecond Ti:Sa ultra-short pulse laser irradiation can be suggested as an alternative to the gold standard sandblasting in long-term Y-TZP zirconia rehabilitations, such as crowns and veneers.     

Sonification and interaction design in computer games for visually impaired individuals

Multimedia Tools and Applications - Video games are changing how we interact and communicate with each other. They can provide an authentic and collaborative platform for building new communities...