Predictions of the thermal conductivity of multiphase nanocomposites with complex structures

Multiphase nanocomposites have drawn substantial attention due to their advanced functionality, including high thermal conductivity. Herein, theoretical models are developed based on modifications of the effective medium theory and then validated to predict the effective thermal conductivity (K_eff) of three common multiphase nanocomposites: nanosheet/nanoparticle/polymer, nanotube/nanoparticle/polymer, and nanosheet/nanotube/polymer. Case studies showed that the predicted K_eff agreed well with available experimental data, validating the developed models. Moreover, quantifiable material properties, like the thermal conductivity of nanofillers, the morphology of nanofillers, and the interfacial thermal resistance around nanofillers, were used to investigate their effects on the K_eff of multiphase nanocomposites. This quantitative study not only can provide simplified strategy to predict the K_eff for diverse multiphase nanocomposites, but it can also guide the design of multiphase nanocomposites with enhanced thermal conductivity.     

Oxidized g‐C3N4 Nanospheres as Catalytically Photoactive Linkers in MOF/g‐C3N4 Composite of Hierarchical Pore Structure

A unique composite of the copper‐based metal–organic framework (Cu‐benzene tricarboxylic acid (BTC)) with oxidized graphitic carbon nitride nanospheres is synthesized. For comparison, a hybrid material consisting of g‐C₃N₄ and Cu‐BTC is also obtained. Their surface features are analyzed using Fourier transform infrared spectroscopy, X‐ray diffraction, sorption of nitrogen, thermal analysis, scanning electron microscopy, photoluminescence, and diffuse reflectance UV–Vis spectroscopy. The results suggest that the formed nanospheres of oxidized g‐C₃N₄ act as linkers between the copper sites, playing a crucial role in the composite building process. Their incorporation to the Cu‐BTC framework causes the development of new mesoporosity. Remarkable alterations in the optical properties, as a result of the coordination of oxygen containing functional groups of the oxidized graphitic carbon nitride to the copper atoms of the framework, suggest an increase in photoreactivity. On the other hand, for the hybrid material consisting of Cu‐BTC and g‐C₃N₄, the unaltered pore volume and optical properties support the formation of a physical mixture rather than of a composite. The tests on reactive adsorption and detoxification of G‐series organophosphate nerve agent surrogate show the enhanced performance of the composite as catalysts and photocatalyst in visible light.     

Detection of defective pile geometries using a coupled FEM/SBFEM approach and an ant colony classification algorithm

Piles are widely used to build a proper foundation for various buildings. The piles’ quality in situ can be tested by a so-called pile integrity test. In order to apply this test, an impulse is given to the piles’ head which generates a p-wave running through the pile. An acceleration sensor is attached to the piles’ head, to measure the vertical movement. The major part of this wave is reflected from the piles’ toe and is measured by the attached acceleration sensor on top of the pile. This yields an acceleration–time plot which has to be analysed in order to determine the piles’ condition with respect to structural consistence and mostly radius defects. Since deviations in the cross section of the pile cause additional reflections, suitable post-processing can be used in order to detect these defects. In this paper, we propose an ant colony classification model to detect structural defects in piles by evaluating displacement–time plots to improve the reliability of pile monitoring. The data of these plots result to numerically performed pile integrity tests. To conduct these tests, a simulation of a combined finite element method and scaled boundary finite element methods has been carried out. These results are used for learning and training the ant colony classification model and to have different sets of data to validate the optimization algorithm. The position and the type of piles’ defect can be identified by the applied algorithm.     

Modular supervisory control for multi-floor manufacturing processes

Due to space availability limitations and high land costs, there is an increasing development of multi-floor manufacturing (MFM) systems in urban and industrial areas. The problem of coordination in a multi-floor manufacturing process, in the Ramadge Wonham framework, is introduced. The manufacturing chain of each floor and the elevator system are modeled in the form of finite deterministic automata. The models of the multi-floor manufacturing process are parametric with respect to the number of floors and the number of manufacturing machines on each floor. The coordination desired performance is formulated in the form of desired regular languages in analytic forms. The languages are realized by appropriate supervisors in the form of finite deterministic automata. The models of the supervisors are also parametric with respect to the number of floors and the number of manufacturing machines on each floor. The total control of the coordination of the multi-floor manufacturing process is accomplished via a modular supervisory control architecture. The complexity of the supervisors as well as the complexity of the total modular supervisory architecture are determined in analytic forms with respect to the number of floors and the number of manufacturing machines on each floor. The special case of a two floor manufacturing process is presented as an illustrative example.     

Modeling the Metal–Insulator Phase Transition in LixCoO2 for Energy and Information Storage

An electro‐chemomechanical phase‐field model is developed to capture the metal–insulator phase transformation along with the structural and chemical changes that occur in Li_xCoO₂ in the regular operating range of 0.5 < x < 1. Under equilibrium, in the regime of phase coexistence, it is found that transport limitations lead to kinetically arrested states that are not determined by strain‐energy minimization. Further, lithiation profiles are obtained for different discharging rates and the experimentally observed voltage plateau is observed. Finally, a simple model is developed to account for the conductivity changes for a polycrystalline Li_xCoO₂ thin film as it transforms from the metallic phase to the insulating phase and a strategy is outlined for memristor design. The theory can therefore be used for modeling Li_xCoO₂‐electrode batteries as well as low voltage nonvolatile redox transistors for neuromorphic computing architectures.     

The impact of arteriovenous fistula creation in pulmonary hypertension: Measurement of pulmonary pressures by right heart catheterization in a patient with respiratory failure following arteriovenous fistula creation

Pulmonary hypertension (PHT) is frequent in patients receiving hemodialysis (HD) and carries a high mortality. While it has been suggested that arteriovenous fistulae (AVF) may exacerbate PHT in HD patients, it has also been observed that creating AVF in patients with chronic lung disease and normal renal function may lead to improved exercise tolerance. Most of the observations regarding HD patients using echocardiography demonstrated that temporary closure of AVF improved pulmonary pressures. We present the case of a 45‐year‐old patient with chronic obstructive pulmonary disease on HD who experienced respiratory failure following AVF formation and underwent right heart catheterization. Severe PHT was diagnosed but transient occlusion of the fistula failed to improve the PHT. This case supports the theory that fistula creation does not exacerbate pre‐existing PHT and that AVF can be the access of choice in patients with known chronic lung disease and pulmonary hypertension.     

Production of activated carbon from agricultural by‐products

The production of activated carbon from agricultural by‐products is a research field of increasing interest as it deals with the problem of the disposal of agro‐residues, at the same time producing an added‐value product that can be used in a number of environmental applications. The paper presents an overview of the latest developments in processes for the production of activated carbon from agricultural by‐products, with emphasis on the methodology applied, the effect of critical process parameters such as retention time, temperature, chemical to material ratio, as well as the adsorbing capacity of the activated carbons produced in removing select compounds from synthetic and real wastewaters. Agricultural by‐products can be a source for activated carbon production with high surface areas and high adsorption capacity. Copyright © 2008 Society of Chemical Industry     

Telematics Service for Home and Satellite Hemodialysis

Home hemodialysis (HD) for the treatment of end-stage renal disease was first implemented about 30 years ago. In this paper the application of telematics monitoring services for supporting patients who need home HD or satellite HD is described. Two modified HD machines were located in two renal units, and a central control station (CCS, UNIX workstation with multimedia PC terminal) was located in another room of the hospital. Bidirectional communication between the modified HD machines and the CCS was managed using ISDN (Integrated Services Digital Network) links. Nine patients had 150 HD sessions performed using these HD machines over a period of 5 months. This system, called the HOMER-D system, provided on-line, remote supervision of the HD machine-related functions and the clinical condition of the patients through measurement of blood pressure, pulse rate, PO₂ (pulse oxymetry), and ECG from the CCS. Any disturbances in the functioning of the HD machines were both visible and audible in the CCS, and the observer could give teleconsultation to the renal unit staff. No major dialysis-associated complications were observed; all data and alarms were transmitted correctly; and patients received adequate HD treatment.