Effect of molecular weight and polymer concentration on the triple temperature/pH/ionic strength-sensitive behavior of poly(2-(dimethylamino)ethyl methacrylate)

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) samples were synthesized via aqueous atom transfer radical polymerization with DP_n of 35, 151, 390, and 546 and dispersity of 1.13, 1.17, 1.20, and 1.18, respectively. All samples were exposed to temperature and pH variations at different concentration of polymer and salt (NaCl). Results indicated that cloud point (T_cl) can be controlled by changing DP_n, polymer concentration, and ionic strength of solution. According to results, T_cl of the PDMAEMA chains shifted to lower temperatures with increasing solution pH at all molecular weight ranges due to deprotonation of tertiary amine groups in polymer structure. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, higher polymer concentration acted as driving force to decrease cloud point of samples and formation of aggregates that was more predominant for higher molecular weights at alkaline media. T_cl of PDMAEMA chains decreased with increasing ionic strength even at low pH values for low molecular weight polymers.     

Hierarchical bioceramic scaffold for tissue engineering: A review

Bioceramic scaffolds have a promising application in bone-tissue engineering field. However, bioceramic scaffolds exhibit low fracture toughness; hence, to overcome this problem, hierarchical bioceramic scaffold or bioceramic scaffolds coated with polymer are produced. Starting with the fundamental requirements for bioceramic scaffold, this article provides detailed information on recent developments of method to produce porous bioceramics scaffold and hierarchical bioceramic scaffold. Chemical modifications to enhance interfacial adhesion and formation of interpenetrating network structures between the bioceramic scaffold and the natural polymer layer are discussed in this article. Areas of future research are highlighted at the end of this review.     

Gross Pollutants Study in Urban Areas under Tropical Climates

Gross pollutants are the primary targeted pollutants in urban catchment management for urban water quality improvement as well as mitigation of flood. Apart from aesthetically unattractive because of its visibility, gross pollutants also contributes to degradation of river water quality and loss of aquatic habitat as it carries harmful pollutants such as oxygen demanding material, hydrocarbons and heavy metals. This study analyzed trend of gross pollutant generated from two urban residential areas located in Selangor, Malaysia. The median value of gross pollutant load obtained fi＇om the Amanah Apartment and Bandar Botanic are 347.41 kg/ha/year and 32.46 kg/ha/year, respectively. Relationship between gross pollutant wet load with rainfall depths was derived using regression equation. A significant trend of increasing gross pollutant wet load into drainage system with increasing rainfall depth was observed. The behavior of pollutant load is related to the one observed in Australia.     

Experimental Determination and Thermodynamic Modeling of the Sn-Rich Corner of the Ternary Ni-Pd-Sn Phase Diagram at 250°C

The Sn-rich portion of the phase diagram for the Ni-Pd-Sn ternary system was preliminarily obtained by interpolation of the three constituent binary systems using the Muggianu method. Based on this proposition, 23 Ni-Pd-Sn alloys were prepared and annealed at 250°C. The annealed alloys were analyzed by scanning electron microscopy, electron probe microanalysis, electron backscatter diffraction, and x-ray diffraction. All the binaries adjacent to the Sn-rich corner (i.e., PdSn₄, PdSn₃, PdSn₂, and Ni₃Sn₄) were found to have remarkable ternary solubility. The experimental results presented herein, together with a thermodynamic interpolation of the ternary system based on the results from the binary systems, were used to calculate the ternary phase diagram using the calculation of phase diagrams (CALPHAD) method. A substitution model was used to describe the Gibbs free energies of the liquid and solid solution phases, and a sublattice model was used to describe intermetallic compounds. A consistent set of thermodynamic parameters was obtained, ultimately leading to a better fit between the calculated results and the experimental data for this system.     

Development of anthropometric data for Bangladeshi male population

An anthropometric study of a group of people is important when designing ergonomic products and workstations for that group. This study surveys the anthropometric dimensions of the Bangladeshi male population between the ages of 15 and 64 years to compare these dimensions with male anthropometrics for different countries available in the literature.