Elasto-Thermodiffusive Response in a Spherically Isotropic Hollow Sphere

The present work deals with the investigation of elasto-thermo diffusion interactions inside a spherically isotropic hollow sphere in the context of linear theory of generalized thermoelastic diffusion based on Green and Lindsay theory. The inner and outer boundaries of the body are free from stresses and are subjected to a time-dependent thermal shock and also the chemical shock. Laplace transform techniques are used to write the basic equations in the form of a vector matrix differential equations, which is then solved by the eigenvalue approach. The inversion of the transformed solution is carried out by applying the method of Bellman. The stress, temperature, mass concentration and chemical potential are computed and presented graphically. A comparative study of diffusive medium and thermoelastic medium is carried out, and it was seen that the effect of diffusion is significant on the stresses. A comparison of spherically isotropic body with isotropic body has also been presented, and a significant difference is observed.     

Functional magnetic nanoshells integrated nanosensor for trace analysis of environmental uranium contamination

Transuranic radionuclides such as uranium tend to be a pervasive environmental contaminant. It is absorbed through the intestine or a lung, deposited in the tissues, predominantly kidney and bone, and is carcinogenic. A novel nanosensor system has been developed for voltammetric tracing of environmental uranium contamination.The sensor consists of an organophosphorous ligand, (t-butylphenyl)-N,N-di-(isobutyl) carbamoylmethylphosphineoxide (CMPO) functionalized superparamagnetic core-shell magnetic nanoparticles and magnet based electrodes. It exploits the natural affinity of uranium for phosphate molecules to fabricate a highly specific and reproducible sensor. The small dimension along with a dramatically increased contact surface has lead to a faster response and higher sensitivity. The system uses an external magnetic field gradient for preconcentration and removal of the analyte from the surrounding aqueous media. The redox properties of the analyte are exploited for enumeration of variables by electrochemical techniques such as square wave voltammetry. The detection limit of the system is observed to be in parts-per-billion (ppb) of the uranyl concentration.     

Combination of Fitness-Mated Lion Algorithm with Neural Network for Optimal Query Ordering Data Aggregation Model in WSN

Query processing can be briefly defined as a database that comprises of an organized collection of data for one or more users either in digital form or in analog form such that it can portray exactly. A Wireless Sensor Network (WSN) is a specialized network of minimum cost, and power sensor nodes that can be described as the ability of performing some processing, gathering sensory information and communicating with each other. Query ordering with data aggregation is the process of scheduling of the nodes to receive the useful data from sensors. Data aggregation is considered as one of the fundamental processing procedures for saving the energy. In WSN data aggregation is an effective way to save the limited resources. This paper proposes a novel query-based data aggregation model with the aid of intelligent techniques. The framing of the query order takes place and the frames are ranked on the basis of a multi-objective function. The newly developed multi-objective function includes Latency, Throughput, and Data freshness. Initially, the solution corresponding to query order is trained in NN using the proposed Fitness-Mated Lion Algorithm (FM-LA). The optimally generated query order from NN is further given for second-level solution generation, which is again applied to FM-LA for subsequent query order optimization. Hence the two-stage optimization process with NN for query ordering is compared over the conventional methods in terms of performance measures like Latency, throughput, and data freshness. Hence, substantiated performance and comparative analysis validate the improved performance of the proposed model.

     

Analysis of spring softening effect on the collapse voltage of capacitive MEMS ultrasonic transducers

Microsystem Technologies - This paper explained the dependency of collapse voltage on semiconductor device structural features (membrane diameter, membrane thickness and the vertical distance...     

Collapse voltage analysis of central annular ring metallized membrane based MEMS micromachined ultrasonic transducer

In this paper we have explored central annular ring metallized capacitive micromachined ultrasonic transducer (CMUT) structure. The metallization is done partially and it is patterned in such a way that it forms a flat ring on the surface of the membrane. This will decrease the price of the device as the need of metallization is less. Moreover, it is seen that the maximum displacement that the membrane can attain just before collapsing does not change even for partial metallization. It is perceived that with decreasing the area of the electrode the collapse voltage increases and vice versa. Changing the gap height has a huge impact on the collapse voltage. We have also examined the effect of different membrane materials on collapse voltage. Changing the membrane thickness hardly affects the value of collapse voltage. The electrode thickness is infinitesimally small as compared to the membrane thickness and is neglected in the analytical modeling approach. The analytical results are compared with three-dimensional (3-D) finite element method (FEM) model results. Excellent agreements between them are observed.

     

Superparamagnetic Nanostructures for Off‐Resonance Magnetic Resonance Spectroscopic Imaging

This study proposes a new method to generate positive contrast in magnetic resonance imaging (MRI) using superparamagnetic contrast agents. Superparamagnetic nanostructures consisting of octahedron manganese ferrite nanoparticles embedded in spherical nanogels are fabricated using a bottom‐up approach. The composite nanoparticles are strongly magnetized in an external magnetic field and produce a unique NMR frequency shift in water protons, which can be demonstrated in MR spectroscopy and imaging to be different from the bulk pool. Moreover, the particles exhibit excellent colloidal stability in aqueous media and good cell biocompatibility. Hence, these particles are potentially useful as biomarkers by taking advantage of the positive contrast effects produced in MRI.     

An electrochemical meter for measuring carbon potential in molten sodium

Thermodynamic analysis and electrochemical investigations were carried out to evaluate the chemistry and electrode kinetics of a molten carbonate based electrochemical carbon meter for monitoring carbon in molten sodium. Based on the results of investigations a procedure was standardized for assembling the cell. The response of the cell thus assembled could be correlated to the carbon activity in sodium. Impedance studies established that mass transfer at iron membrane was the rate limiting step. Meters were extensively tested in both static and dynamic sodium for evaluating the stability and reproducibility in long term conditions.     

Design,Development, and Evaluation of an Interwoven Electrospun Nanotextile Vascular Patch

This study details the design and fabrication of woven electrospun nanotextile patches for vascular applications that meet the mechanical and biological requirements. Nanotextile vascular patches based on biodegradable polymers such as poly-l -lactic acid (PLLA) and poly(caprolactone)/collagen (PCL/Col) are fabricated by integrating the techniques of electrospinning and weaving. Fibrous polymeric nanoyarns obtained by electrospinning are strengthened via different postprocessing techniques of heat-stretching and plying, to generate interwoven nanotextiles that are tightly packed, mechanically strong, yet flexible. The unique pattern of nanofibers within the nanotextile results in its exceptional anisotropic mechanical behavior, appropriate for a vascular patch material. Moreover, these matrices exhibit good hydrophilicity, protein adsorption, and hemocompatibility, when compared to the commercial controls such as expanded polytetrafluoroethylene (ePTFE) and polyethylene terephthalate (PET). Furthermore, endothelial cells adhered, spread, and proliferate well on the nanotextile. Thus, this study demonstrates that the unique nanofibrous architecture of woven textiles aids in developing a novel biodegradable material, which meets the clinical standards of a vascular patch.     

Silicone bridged iron metallocene butadiene composite solid propellant binder: aspects of thermal decomposition kinetics,pyrolysis and propellant burning rate

Propellant binders are essential components of composite solid propellants (CSP’s) used in launch vehicles and missiles. Binders act as a fuel and contribute directly to the combustion in conjunction with oxidizer particles and metallic fuel apart from imparting structural integrity to the solid propellant grain .The performance of CSP’s are directly related to the burn rate of the propellant. The burn rates of the ammonium perchlorate (AP) propellants are generally moderated using various types of transition metal oxide (TMO) catalysts. However, TMO’s are associated with inherently large dispersions in propellant burn rates and compromise on energetics. One of the most suitable methods for achieving lower dispersion in burn rate is using binders wherein a burn rate catalyst is grafted to the polymer matrix. In the present paper, the thermal decomposition of ferrocene bound hydroxyl terminated polybutadiene (FC-Si-HTPB) grafted to butadiene backbone via hydrosilylation was investigated The thermal degradation mechanism, stability and its effectiveness as burn rate catalyst are the most important aspects for use in CSP’s. The mechanism of decomposition of the neat resin and in combination with AP has been elucidated using pyrolysis gas chromatography–mass spectrometric technique (GC-MS). FC-Si-HTPB exhibits single stage decomposition in the temperature range of 263–491°C. The decomposition of FC-Si-HTPB with AP oxidizer follows a two stage mechanism in the 195–490°C.The char residue was characterized using FTIR, Raman spectroscopy and FE-SEM analysis, which enables to vindicate the mechanism of reaction. The activation energy for the decomposition of HTPB is 283.6 kJ/mol, FC-Si-HTPB is 251.5 kJ/mol and for Fc-Si-HTPB-AP system is 67.1 kJ/mol. The major pyrolysis products of neat FC-Si-HTPB are ferrocenyl derivatives, silylated ferrocenyl derivatives and precursors emanating from polybutadiene backbone. The propellants based on the new binder exhibited an increase in burn rate with iron content and higher fine content. A comparison of propellant burn rate with conventional micron sized ferric oxide exhibited an improvement of 34%.Based on the thermal analysis studies, the thermal endurance of the system was computed to be FC-HTPB> HTPB> FC-HTPB-AP.