Analytical modeling of the elastic structural response of tubes to internal detonation loading

The internal detonation loading of cylindrical shells involves loads that propagate at high speeds. Since the speed of the gaseous detonation can be comparable to the flexural-wave-group speed, the excitations of flexural waves in the tube wall become significant. Flexural waves can result in high strains, which may exceed the equivalent static strains (caused by the same nominal loading pressure) by up to a factor of 4. This paper presents a new analytical model for the transient elastodynamic structural response of cylindrical shells with finite length to internal detonation loading. It is shown that, due to the consideration of the effects of transverse shear and rotary inertia, the predictions of dynamic structural response of tubes provided by this model are in better agreement with the experimental results, than existing analytical models. The model is verified through comparison with experimental results reported in the literature.     

The effect of process parameters on the size and morphology of poly(D,L‐lactide‐co‐glycolide) micro/nanoparticles prepared by an oil in oil emulsion/solvent evaporation technique

For the past few decades, there has been a considerable research interest in the area of biodegradable polymeric micro‐ and nanoparticles for tissue engineering, regenerative medicine, implants, stents, medical devices, and drug delivery systems. Poly(D,L ‐lactide‐co‐glycolide) (PLGA) is well‐known by its safety in biomedical preparations which has been approved for human use by the FDA. The goal of this study was to evaluate the influence of process parameters on size characteristics of PLGA microparticles prepared by oil in oil (o/o) solvent evaporation technique. This method has been introduced as one of the most appropriate methods for hydrophilic agents. Scanning electron microscopy showed that prepared particles were spherical with smooth surface without aggregation. Particle size varied from 570 nm to 29 μm in different experimental conditions. Stirring speed, polymer concentration, impeller type, and dropping size had a significant effect on the particle size. The polydispersity index of particles showed a strong relationship with the surfactant concentration, impeller type, and dropping size. It was concluded that increasing in temperature up to 50°C or changing in dropping rate has a little effect on reducing the size of PLGA particles. The residual solvent content in the final suspension was less than 0.1 ppm that is in appropriate range for biomedical application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Hydrogen gas sensing properties of microwave-assisted 2D Hybrid Pd/rGO: Effect of temperature,humidity and UV illumination

A novel microwave assisted two-dimensional (2D) hybrid material based on nanostructured reduced graphene oxide (rGO) doped with Pd nanoparticles (Pd/rGO) has been synthesised to investigate its hydrogen sensing performance at different operational conditions. The sensing performance has been evaluated at various operating temperatures (room temperature up to 120 °C), hydrogen concentrations (up to 1%), and relative humidity (up to ~44%). The material characterization of the hybrid Pd/rGO analysed by different techniques which confirms homogeneous distribution of Pd NPs (<35 nm) on the multi-layered porous structure of the rGO nanosheets (NSs) and forming the hybrid Pd/rGO NSs. Moreover, the fundamental hydrogen sensing mechanism as well as recovery enhancement by ultraviolet (UV) light are investigated. This work offers an environmentally friendly and energy-saving synthesis approach for hydrogen sensing with excellent control over experimental parameters which can lead to fabrication of a highly selective and sensitive hydrogen sensor.     

A novel microfluidics integrated biosensor based on a MEMS resonator

Microsystem Technologies - In this paper a sensor based on MEMS resonators is proposed for digital microfluidics applications. The sensor system consists of a disk as active area immobilized for...     

Green Synthesis of Chitosan-Coated Silver Nanoparticle,Characterization, Antimicrobial Activities,and Cytotoxicity Analysis in Cancerous and Normal Cell Lines

Journal of Inorganic and Organometallic Polymers and Materials - The production of silver nanoparticles (AgNPs) using chemical synthesis routes require hazardous and toxic solvents. Nowadays, there...     

Introduction of a chaotic dough mixer, part A: mathematical modeling and numerical simulation

The motivation of this work is to propose a special dough mixer with chaotic advection to take advantage of high performance mixing in chaotic mixers and to develop typical dough mixers. In order to prevent common difficulties encountered due to the dynamic mesh, a mathematical model was employed based on neglecting the transient term of the momentum equation using conceptual features from creeping flow. Then, the numerical simulation was performed using the bird Carreau dough model of Dhanasekharan. The mathematical model was further developed to complete the numerical procedure in order to find the required material point trajectories for assessing the presence of chaotic advection in the proposed mixer. In this approach, Lyapunov exponents were also calculated which quantify the exponential divergence of the initially close state-space trajectories and identify chaotic behavior of the system as well. The results indicated that the flow field was a combination of both chaotic and non-chaotic zones.     

Investigation of the effect of the flame holder geometry on the flame structure in non-premixed hydrogen-hydrocarbon composite fuel combustion

In this paper, the effect of the flame holder geometry on the flame structure of a mixed hydrogen-hydrocarbon fuel is numerically studied. The fuels used in this study are 100% H₂, 50% H₂ + 50% CH₄, and 100%CH₄. Numerical results obtained by using the k-? and β-PDF models show good agreement with experimental data. The results show that increasing both the flame holder length and hydrogen percentage in the fuel decreases the flame length. The flame temperature decreases with decreasing flame holder length. Adding hydrogen to methane increases the peak temperature of the flame and moves its location toward the burner inlet. It is observed that the dependence of the flame length as a function of the flame holder diameter has a minimum at a certain value of the latter. The flame temperature is higher for smaller flame lengths.     

Co‐delivery of methotrexate and doxorubicin via nanocarriers of star‐like poly(DMAEMA‐block‐HEMA‐block‐AAc) terpolymers

Combined therapy is a promising strategy for clinical cancer treatment with synergistic effects. The purpose of the work reported was to evaluate a smart nanocarrier for co‐delivery of doxorubicin (DOX) and methotrexate (MTX). Since star‐like nanocarriers can load a high dose of drugs with various properties, we developed star polymer nanomicelles based on poly[(2,2‐dimethylaminoethyl methacrylate)‐block‐(2‐hydroxyethyl methacrylate)‐block‐(acrylic acid)] having potential for multi‐drug delivery. The nanomicelles demonstrated high encapsulation efficiency, i.e. 97.1% for DOX and 79.5% for MTX. To this end, the star‐like terpolymers were synthesized via atom transfer radical polymerization with pentaerythritol as an initiator. The micellar properties and dual stimuli‐responsive behaviour of the terpolymers were investigated using transmission electron microscopy, field emission scanning electron microscopy and dynamic light scattering measurements, concluding that this co‐therapy offers a promising approach for cancer treatment. © 2019 Society of Chemical Industry