Interference Mitigation in Wireless Body Area Networks Using Modified and Modulated MHP

Wireless Body Area Networks (WBAN) is an emerging area in field of remote health monitoring and telemedicine. UWB is a preferred candidate for the WBAN as it provides very high data rate at minimal cost and power consumption. Since the UWB-WBAN is wireless, it will be affected by interference from existing wireless personal and local area networks. Interference immunity is a major issue in wireless Body Area Networks as patients’ vital data containing details of functioning of vital organs and blood flow are carried. The paper investigates the performance of modified and modulated hermite pulses (MHP) for narrowband interference mitigation in the 4,940–4,990 MHz band IEEE 802.11y Public Safety band interference. This 50 MHz interfering band will be a critical interferer due to the higher power levels of interfering system. Performance of the proposed technique have been shown in comparison with Gaussian pulse shapes and has been further validated by transmitting ECG and MRI data by it in presence of strong interference.     

Antimicrobial Particulate Silver Coatings on Stainless Steel Implants for Fracture Management

We have used particulate silver coating on stainless steel to prevent in vivo bacterial infection. Stainless steel is commonly used as an implant material for fracture management. The antimicrobial use of silver has been well documented and studied, therefore the novelty of this research is the use of a particulate coating as well as facing the real world challenges of a fracture repair implant. The variable parameters for applying the coating were time of deposition, silver solution concentration, voltage applied, heat treatment temperature between 400 to 500 °C and time. The resultant coating is shown to be non-toxic to human osteoblasts using an MTT assay for proliferation and SEM images for morphology. In vitro silver release studies of various treatments were done using simulated body fluid. The bactericidal effects were tested by challenging the coatings with P. aeruginosa in a bioreactor and compared against uncoated stainless steel. A 13-fold reduction in bacteria was observed at 24 hours and proved to be statistically significant.     

Microwave sintering of calcium phosphate ceramics

Microwave sintering of hydroxyapatite (HAP) and tri-calcium phosphate (TCP) ceramics were studied using a commercial 2.45 GHz, 3 KW fully automated microwave system. Four different powder compositions, apart from pure HAP and TCP, were prepared with small amount of different oxide additives e.g., magnesium oxide, zinc oxide and titanium oxide. All samples were densified at 1250 °C for 30 min. Sintered samples had high density and homogeneous microstructure for all compositions. Phase analysis using XRD showed no major variations from starting materials. Presence of additives increased compressive strength between 100 and 200%. Fractured surfaces showed clear signs of intergranular fracture in undoped HAP and TCP while in doped samples, fracture modes were either transgranular or mixed mode. In comparison to conventional sintering, microwave sintering of calcium phosphate ceramics was found to be economically exciting due to substantial reduction in processing time and energy expenditure due to volumetric heating of samples.     

Applying modified NSGA-II for bi-objective supply chain problem

This paper minimizes the value of total cost and bullwhip effect in a supply chain. The objectives have been achieved through developing a new multi-objective formulation for minimizing the total cost and minimizing the bullwhip effect of a two-echelon serial supply chain. A new crossover algorithm for a fuzzy variable and a new mutation algorithm have also been proposed while applying Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to the proposed problem. The formulated problem has been simulated by Matlab software and the results of the modified NSGA-II have been compared with those of original NSGA-II. It is found from the results that the modified NSGA-II algorithm performs better than the original NSGA-II algorithm since the minimum values for both total cost and the bullwhip effect are obtained in case of the modified NSGA-II. The formulated bi-objective problem is new to the research community. The minimization of bullwhip effect has never been considered in a multi-objective optimization before. Besides crossover operator applied to the fuzzy variable and the mutation operator are newly introduced operators.     

Tricalcium phosphate based resorbable ceramics: Influence of NaF and CaO addition

Resorbable bioceramics have gained much attention due to their time-varying mechanical properties in-vivo. Implanted ceramics degrade allowing bone in-growth and eventual replacement of the artificial material with natural tissue. Calcium phosphate based materials have caught the most significant attention because of their excellent biocompatibility and compositional similarities to natural bone. Doping these ceramics with various metal ions has significantly influenced their properties. In this study, tricalcium phosphate (TCP) compacts were fabricated via uniaxial compression with five compositions: (i) pure TCP, (ii) TCP with 2.0 wt.% NaF, (iii) TCP with 3.0 wt.% CaO, (iv) TCP with a binary of 2.0 wt.% NaF and 0.5 wt.% Ag₂O, and (v) TCP with a quaternary of 1.0 wt.% TiO₂, 0.5 wt.% Ag₂O, 2.0 wt.% NaF, and 3.0 wt.% CaO. These compacts were sintered at 1250 °C for 4 h to obtain dense ceramic structures. Phase analyses were carried out using X-ray diffraction. The presence of NaF in TCP improved densification and increased compression strength from 70 (± 25) to 130 (± 40) MPa. Addition of CaO had no influence on density or strength. Human osteoblast cell growth behavior was studied using an osteoprecursor cell line (OPC 1) to assure that the biocompatibility of these ceramics was not altered due to the dopants. For long-term biodegradation studies, density, weight change, surface microstructure, and uniaxial compression strength were measured as a function of time in a simulated body fluid (SBF). Weight gain in SBF correlated strongly with precipitation viewed in the inter-connected pores of the samples. After 3 months in SBF, all samples displayed a reduction in strength. NaF, CaO and the quaternary compositions maintained the most steady strength loss under SBF.