Recent advances in synthesis,characterization, and applications of nanoparticles for contaminated water treatment- A review

The major issue of consumable water shortage in different parts of the world has piqued the interest of researchers around the globe towards finding out novel, efficient and cost-effective means and techniques for treatment of contaminated water. Towards such efforts, researchers are experimenting with various types of nanoparticles for observing their abilities to treat polluted and/or wastewater. Numerous types of nanoparticles such as carbon-based nanoparticles, semiconductor nanoparticles, ceramic nanoparticles, polymeric nanoparticles, metal nanoparticles, magnetic nanoparticles, etc. are widely tested to confirm their applicability as potential candidates for contaminated as well as wastewater treatment. Different types of nanoparticles offer specific advantages depending on their composition, physical, chemical, electrical, magnetic and structural characteristics. Nanoparticles such as nanoferrites are reported to be easily separated, regenerated and reused up to several runs without incurring any loss in their properties which tend to significantly reduce operations costs. The present study provides a detailed review of the various synthesis and characterization techniques for the production of the nanoparticles. The present study also reviews the current progress, made particularly during the last two decades, in the application of nanoparticles for successful removal of organic, metallic as well as pathogenic pollutants from the water. This review aims to highlight the unlimited potential of nanoparticles and their derivatives in the domain of contaminated and wastewater treatment.     

Green Formation of Robust Supraparticles for Cargo Protection and Hazards Control in Natural Environments

In parallel with important technological advances, nanoparticles have brought numerous environmental and toxicological challenges due to their high mobility and nonspecific surface activity. The hazards associated with nanoparticles can be significantly reduced while simultaneously keeping their inherent benefits by superstructuring. In this study, a low‐temperature and versatile methodology is employed to structure nanoparticles into controlled morphologies from biogenic silica, used as a main building block, together with cellulose nanofibrils, which promote cohesion. The resultant superstructures are evaluated for cargo loading/unloading of a model, green biomolecule (thymol), and for photo‐accessibility and mobility in soil. The bio‐based superstructures resist extremely high mechanical loading without catastrophic failure, even after severe chemical and heat treatments. Additionally, the process allows pre and in situ loading, and reutilization, achieving remarkable dynamic payloads as high as 90 mg g^?1. The proposed new and facile methodology is expected to offer a wide range of opportunities for the application of superstructures in sensitive and natural environments.     

Modeling representative Gen‐IV molten fuel reactivity effects in the ZEPHYR fast/thermal coupled ZPRs. Part I—Assembly level

The comprehension of severe criticality accident is a key issue in Gen‐IV neutronics and safety. Within the future zero‐power experimental physics reactor (ZEPHYR), to be built in Cadarache in the next decade, innovative approaches to reproduce high temperature partially degraded Gen‐IV cores into a critical facility is being investigated. This work presents the first attempt to represent a fuel assembly of sodium‐cooled fast reactor severe criticality accident based on surrogate models. One identified way to construct such representative configuration is to use MASURCA plates stockpile (MOX, UOx, Na, U, and Pu metal) in a fast/thermal coupled core to model a stratified molten assembly. The present study is the first step in a more global approach to full core analysis. The approach is based on a nature‐inspired metaheuristic algorithm, the particle swarm optimization algorithm, to find relevant ZEPHYR configuration at 20°C that exhibits characteristics of (2000‐3000°C) molten MOX assembly in a stratified metal arrangement in a reference sodium‐cooled fast reactor core. Thus, the underlying research question of this study is whether it is possible to represent temperature‐related reactivity effects occurring at fuel meltdown temperatures in a power reactor as density‐related reactivity effects at the operation temperature of a zero‐power reactor, and if so, how should it be done? The calculations are based on a Serpent‐2 Monte Carlo sensitivity and representativity analysis using the Cadarache's cross sections covariance data (COMAC). The single fuel assembly studies show that it is possible to represent the multiplication factor with a representativity factor greater than 0.98. As for reactivity variations, it is possible to achieve a satisfactory representativity factor of above 0.85 in all the presented cases. The representativity process demonstrates that temperature effects could be translated into density effects with good confidence. A complementary analysis on modified nuclear data covariance matrix demonstrates the importance of selecting consistent and robust uncertainties in the particle swarm optimization algorithm. This work provides insights on the behavior of the representativity scheme in different core states and shades some light on the problem in hand.     

Advantages of a 3-parameter reduced constitutive model for the measurement of polymers elastic modulus using tensile tests

Exact measurements of the rheological parameters of time-dependent materials are crucial to improve our understanding of their intimate relation to the internal bulk microstructure. Concerning solid polymers and the apparently simple determination of Young’s modulus in tensile tests, international standards rely on basic protocols that are known to lead to erroneous values. This paper describes an approach allowing a correct measurement of the instantaneous elastic modulus of polymers by a tensile test. It is based on the use of an appropriate reduced model to describe the behavior of the material up to great strains, together with well-established principles of parameter estimation in engineering science. These principles are objective tools that are used to determine which parameters of a model can be correctly identified according to the informational content of a given data set. The assessment of the methodology and of the measurements is accomplished by comparing the results with those obtained from two other physical experiments, probing the material response at small temporal and length scales, namely, ultrasound measurements with excitation at 5 MHz and modulated nanoindentation tests over a few nanometers of amplitude.     

Distributed system design based on dependability evaluation: a case study on a pilot thermal process

The aim of this paper is to test and validate a methodology for the design of distributed systems by evaluating performances and dependability (more specially reliability and availability). The optimal material architecture of the automation system is determined from an over-dimensioned preliminary material architecture, and from the functional decomposition of this system. The interest of this method is to allow an early comparison of several choices of architecture, and of sets of components, during the designing of the system. One of the results of our work is described below as the application of the method for the designing of a pilot thermal process.     

Gonadotropin-I and -II subunit gene expression of male striped bass (Morone saxatilis) after gonadotropin-releasing hormone analogue injection: quantitation using an optimized ribonuclease protection assay

We have demonstrated that sodium butyrate induces differentiation in human hepatoma cells; however, recent studies have shown that this agent causes apoptosis in some types of cancer cells. In this study, we examined whether sodium butyrate causes apoptosis in the human hepatoma cell lines, HCC-M and HCC-T. The growth of human hepatoma cells was dose-dependently reduced by sodium butyrate. Flow cytometric analysis showed cell-cycle arrest at the G1 phase in the sodium butyrate-treated cells. Apoptotic change was never found in treated cells at concentration levels of less than 5 mmol/L. Sodium butyrate decreased p53 expression and increased p21WAF-1 expression in HCC-T and HCC-M cells having the wild-type p53 gene. Western blot analysis showed that Bcl-2 was expressed in the HCC-T and HCC-M cells, and its expression was increased after exposure to sodium butyrate. Antisense oligodeoxynucleotide against bcl-2 easily caused apoptosis. These results indicate that sodium butyrate hardly induces apoptotic change in the human hepatoma cell lines, HCC-T and HCC-M, with the increase of Bcl-2 expression. Cell-cycle arrest in the G1 phase caused by sodium butyrate was suggested to be induced by the increase in p21WAF-1 expression, but this change did not link with the p53 increase.     

Metatheorizing citation

This paper reviews a variety of perspectives on citation. It argues that citations have multiple articulations in that they inform our understanding of the socio-cultural, cognitive, and textual aspects of scientific communication. Two metatheoretical frameworks are proposed as a means of negotiating the interpretative differences which characterize the various discourse communities concerned with citation theory and practice.     

Ground Response in Lotung: Total Stress Analyses and Parametric Studies

Previous papers have reported on the performance of a recently developed nonlinear ground response analysis code, SPECTRA, with reference to the prediction of the free-field response at a Large-Scale Seismic Test site in Lotung, Taiwan during the M6.5 earthquake of May 20, 1986. Two more major earthquakes of different characteristics shook this test site later that same year, a M6.2 earthquake that occurred on July 30 and a M7.0 earthquake that occurred on November 15. The present article analyzes the free-field responses recorded by a downhole array from these latter two events using the code SPECTRA and a widely used equivalent linear analysis code SHAKE. The studies focus on the relative accuracy and sensitivity of the two codes with respect to the variations of the input material parameters, using time histories, acceleration response spectra, Fourier acceleration amplitude spectra, and Arias intensities as criteria for the comparison. The two codes captured the general wave form of the acceleration histories well, but there was a general tendency for both codes (particularly SHAKE) to underpredict the Arias intensities of the earthquakes.     

Quasi-static scheduling of communicating tasks

Good scheduling policies for distributed embedded applications are required for meeting hard real time constraints and for optimizing the use of computational resources. We study the quasi-static scheduling problem in which (uncontrollable) control flow branchings can influence scheduling decisions at run time. Our abstracted distributed task model consists of a network of sequential processes that communicate via point-to-point buffers. In each round, the task gets activated by a request from the environment. When the task has finished computing the required responses, it reaches a pre-determined configuration and is ready to receive a new request from the environment. For such systems, we prove that determining the existence of a scheduling policy that guarantees upper bounds on buffer capacities is undecidable. However, we show that the problem is decidable for the important subclass of “data-branching” systems in which control flow branchings are exclusively due to data-dependent internal choices made by the sequential components. This decidability result exploits ideas derived from the Karp and Miller coverability tree for Petri nets as well as the existential boundedness notion of languages of message sequence charts.     

Central electric thermal storage (ETS) feasibility for residential applications: Part 1. Numerical and experimental study

Detailed models have been developed and integrated into a TRNSYS calculation tool to evaluate the optimal storage capacity of central electric thermal storage (ETS) units for residential applications. The tool uses hourly weather data to establish the energy use profile of residential buildings under different heating system configurations and control strategies. The reliability of the system for each configuration is determined as the percentage of time the heating system meets the heating requirement of the building. The level of reliability is used to evaluate the appropriate capacity of the system. This study investigates the theoretical development and modelling of a multi‐zone building equipped with a central ETS in TRNSYS. The TRNSYS simulation results are then compared and validated against experimental data obtained during the project. Furthermore, the effect of various parameters such as system configuration, charging capacity, control strategies, heat losses from the building, and electric utility time‐of‐use schedules are analysed. Copyright © 2001 John Wiley & Sons, Ltd.