Calcium phosphate ceramics in drug delivery

Calcium phosphate (CaP) particulates, cements and scaffolds have attracted significant interest as drug delivery vehicles. CaP systems, including both hydroxyapaptite and tricalcium phosphates, possess variable stoichiometry, functionality and dissolution properties which make them suitable for cellular delivery. Their chemical similarity to bone and thus biocompatibility, as well as variable surface charge density contribute to their controlled release properties. Among specific research areas, nanoparticle size, morphology, surface area due to porosity, and chemistry controlled release kinetics are the most active. This article discusses CaP systems in their particulate, cements, and scaffold forms for drug, protein, and growth factor delivery toward orthopedic and dental applications.     

Estimation of Path Loss Model for a 2.65 GHz Mobile WiMAX Network Deployed in a Sub-Urban Environment with Regression Techniques

Deployment of an efficient cellular network is considered as a challenging task as it affects the performance measures like data rate, bit error rate, spectrum efficiency and energy efficiency etc. For this, the foremost important step is developing an accurate path loss model for the network in the deployment region. In this paper, an empirical path loss model is estimated for an IEEE 802.16e standardised WiMAX network operating on a carrier frequency of 2.65 GHz deployed in a sub-urban area. An experimental setup is designed for collecting the parameters such as carrier to interference plus noise ratio (CINR), received signal strength indicator (RSSI) for the concerned network and with the help of regression technique, the path loss model is formulated. The relationships between CINR, RSSI, and the distance between base station and customer premise equipment are formulated. The distributions of RSSI, CINR and path loss for the concerned network are also found out. Then by using the proposed path loss model, link budget analysis is performed. From the analysis, it is concluded that the proposed path loss model closely approximates to Stanford University Interim model with path loss exponent value of 3.45.     

Laser surface modification of metallic biomaterials

Load-bearing metal implants often fail prematurely due to inadequate biocompatibility, mechanical/tribological properties, and poor osseointegration. It is well known that biomaterials’ surface plays a vital role in the response to these metal implants in the biological environment. The biological effectiveness of artificial implants is determined mainly by their surface characteristics such as surface morphology, microstructure, composition, mechanical properties, wettabilility, and surface free energy. Hence, there is significant interest toward surface modification and effective design of load-bearing metal implants so as to improve their surface properties and thereby elicit a specific, desired, and timely response from the surrounding cells and tissues. In this article, we provide an insight into laser surface modification of Ti/Ti6Al4V alloy with or without functional gradation in composition and their microstructural, in vitro wear and biological properties for various loadbearing orthopedic applications.     

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.     

Synthesis of Hydroxyapatite Nanopowders via Sucrose-Templated Sol–Gel Method

The present research describes synthesis of hydroxyapatite (HAp) nanopowders using a sol–gel route with calcium nitrate and ammonium hydrogen phosphate as calcium and phosphorous precursors, respectively. Sucrose is used as template material, and alumina is added as a dopant to study its effects on particle size and surface area. Synthesized powders are characterized using X-ray diffractometry, BET surface-area analysis, and transmission electron microscopy. Results show that alumina stabilizes the HAp crystalline phase. Average particle size of mesoporous HAp samples is between 30 and 50 nm with surface area of 51–60 m²/g.     

Finite element analysis of piezoelectric thin film membrane structures

Thin film structures have found a wide variety of applications in electromechanical technologies. As the design flexibility for these structures increases, so does the demand for design software that can provide some good insights into the behavior of the structure before it is fabricated. In this study, a finite element code based on a combination of equivalent single-plate theory and classical laminated plate theory was used to predict the dynamic response of thin film structures in micro length scale. As a benchmark for the code development, thin film structures were also fabricated using MEMS technology, and their fundamental frequencies were characterized. It was demonstrated that the model predictions matched fairly well with the experimental data for the small membranes with widths less than 200 microm, but underestimated them for large ones with widths greater than 500 microm. The model also demonstrated that the fundamental frequencies increased with the thickness of the layers. The areas that need to be investigated further in order to improve the predicative capability of the calculations include effects of residual stress, dc bias voltage, parasitic capacitance, interaction of membrane vibration with the supports of the structure, and accurate measurement of the dimensions and material properties of the thin films.