Protection of structures subject to seismic and mechanical vibrations using periodical networks

The concept of frequency gaps in phononic crystals is widely used in physics. The feasibility and efficiency of applying this principle in damping out seismic and mechanical induced vibrations in real scale of civil engineering constructions are presented in this article through the results obtained from numerical modeling and analysis of a concrete substratum embedding steel elements (pillars) coated in a polyvinyl chloride polymer (PVC). The first configuration having the elements fully embedded into the substrate resulted in two narrow band gaps at relatively high frequencies; and when only the metallic pillars are emerging from the substrate, the band gaps shift towards the low frequencies. The results are improved and show the existence of three band gaps at medium frequencies ranging from 80 to 200 m/s when both the pillars and the polymer are emerging from the foundation. Exploring other metal-polymer pairs of materials such as "steel-rubber", "steel-silicone"," lead-rubber" and "lead-silicone", shows that a range of band gaps has shifted again towards the lower frequencies which cover part of the seismic frequency domain. Further improvement is obtained by notching the ends of the substrate in order to widen and lower the band gaps especially for "metal-rubber" pairs. These results show the potential of using periodic networks to mitigate seismic and mechanical vibration effects on large scale structures and components

Protection of structures subject to seismic and mechanical vibrations using periodical networks

The concept of frequency gaps in phononic crystals is widely used in physics. The feasibility and efficiency of applying this principle in damping out seismic and mechanical induced vibrations in real scale of civil engineering constructions are presented in this article through the results obtained from numerical modeling and analysis of a concrete substratum embedding steel elements (pillars) coated in a polyvinyl chloride polymer (PVC). The first configuration having the elements fully embedded into the substrate resulted in two narrow band gaps at relatively high frequencies; and when only the metallic pillars are emerging from the substrate, the band gaps shift towards the low frequencies. The results are improved and show the existence of three band gaps at medium frequencies ranging from 80 to 200 m/s when both the pillars and the polymer are emerging from the foundation. Exploring other metal-polymer pairs of materials such as "steel-rubber", "steel-silicone"," lead-rubber" and "lead-silicone", shows that a range of band gaps has shifted again towards the lower frequencies which cover part of the seismic frequency domain. Further improvement is obtained by notching the ends of the substrate in order to widen and lower the band gaps especially for "metal-rubber" pairs. These results show the potential of using periodic networks to mitigate seismic and mechanical vibration effects on large scale structures and components

Band Gaps of structures based on concrete-steel and concrete-molybdenum. Comparison between structures with square and hexagonal periodicities

In this article, a study of the frequency dispersion curves of a periodic structure was made. The cell units of the base model are made of steel cylinders coated with a rubber layer embedded in a concrete thin mat. The results show the existence of three band gaps which means that we have no propagation waves. In second step, the steel core has been substituted with molybdenum. A noticeable shift towards the low frequencies has been achieved together with an improvement in the relative widths of the band gaps. In addition, a comparison of band gaps was made between a finites two-dimensional structure with square periodicity and hexagonal periodicity. The results showed that a square periodicity of a two-dimensional structure is more favourable for the field of civil engineering wich is necessary to be in a low frequencies

Review on discharge Plasma for water treatment: mechanism, reactor geometries, active species and combined processes

Owing to the water crisis, the development of innovative and clean advanced oxidation processes to decompose a variety of harmful organic compounds in wastewater becomes the main challenge for many research teams. Cold discharge plasma is one of the most widely studied and developed processes, owing to its low energy cost and easy to operate. The impact of different factors on the decontamination effectiveness of discharge plasma are detailed in this review. The generation and reaction mechanisms of reactive species in discharge plasma systems have also gained a significant interest and hence discussed. Several potentials and laboratory-scale reactor design recently reported are discussed and schematically presented. The recent combination of discharge plasma decontamination and other processes in both post and pre-treatment configuration are reported. Some applications of water treatment based on discharge plasma at the pilot scale have been addressing

Synthesis of novel biocomposite powder for simultaneous removal of hazardous ciprofloxacin and methylene blue: Central composite design, kinetic and isotherm studies using Brouers-Sotolongo family models

Over the past decades, extensive efforts have been made to use biomass-based-materials for wastewater-treatment. The first purpose of this study was to develop and characterize regenerated-reed/reed-charcoal (RR-ChR), an enhanced biosorbent from Tunisian-reed (Phragmites-australis). The second aim was to assess and optimize the RR-ChR use for the removal of binary ciprofloxacin antibiotic (CIP) and methylene blue dye (MB), using Central Composite Design under Response Surface methodology. The third purpose was to explain the mechanisms involved in the biosorption-process. The study revealed that the highest removal-percentages (76.66 % for the CIP and 100 % for the MB) were obtained under optimum conditions: 1.55 g/L of adsorbent, 35 mg/L of CIP, 75 mg/L of MB, a pH of 10.42 and 115.28 min contact time. It showed that the CIP biosorption mechanism was described by Brouers–Sotolongo-fractal model, with regression-coefficient (R2) of 0.9994 and a Person’s Chi-square (X2) of 0.01. The Hill kinetic model better described the MB biosorption (R2 = 1 and X2 = 1.0E-4). The isotherm studies showed that the adsorbent surface was heterogeneous and the best nonlinear-fit was obtained with the Jovanovich (R2 = 0.9711), and Brouers–Sotolongo (R2 = 0.9723) models, for the CIP and MB adsorption, respectively. Finally, the RR-ChR lignocellulosic-biocomposite-powder could be adopted as efficient and cost-effective adsorbent

Characterization of cardinal vine shoot waste as new resource of lignocellulosic biomass and valorization into value-added chemical using Plackett-Burman and Box Behnken

International audienceThe objective of this work was to valorize a waste from cardinal vine shoot into a hydrolysate rich in reducing sugars. Plackett-Burman design was considered to identify the significant factors, while a Box Behnken design was considered to optimize the extraction in the following experimental conditions: 100 degrees C, 750 rpm, trifluoracetic acid (CF3O2H) concentration (TFA) in the range (1-10%), for 20 to 180 min and considering the following solid-liquid (S/V) ratios (1:1, 3:1, 5:1). The optimal result was 2.53% in sugars equivalent to a yield of 50.64% per gram of dry matter. Shoot vine waste was characterized by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), simultaneous thermal analysis (STA), and X-ray fluorescence (XRF). The chemical composition was 43.38% cellulose, 23.58% hemicellulose, 21.22% lignin, 2.53% ash, 5.82% crude protein, 11.7% moisture, and extractives (0.81% fat, 0.56% total sugars, 2.3% extractive (hexane-ethanol)). The promising potential of shoot vine waste to produce sugar and other added-value compounds was demonstrated

The use of a forest waste biomass, cone of Pinus brutia for the removal of an anionic azo dye Congo red from aqueous medium

International audienceCone biomass of Pinus brutia, a novel low-cost adsorbent prepared from forest waste has been utilized as an adsorbent for the removal of Congo red (CR) dye from an aqueous solution. The adsorbate concentration, pH, time, and temperature were examined in batch tests. Maximum biosorption capacity was 102.8 mg/g, showing that cone biomass of P. brutia was more efficient than most of the other adsorbents. Experimental data were analyzed by Langmuir, Freundlich, and Sips adsorption isotherms models and showed that the adsorption process followed a Sips model. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to fit experimental data, showing that the adsorption of CR could be described by a pseudo-second-order equation and that intraparticle diffusion was not the only rate-limiting mechanism for the biosorption of CR. Thermodynamic parameters such as ΔGo, ΔHo, and ΔSo were also evaluated and it was found that the sorption process was feasible, spontaneous, and endothermic in nature. These results indicated that cone biomass of P. brutia is promising as a low-cost alternative compared to other commercial adsorbents for the removal of dyes from wastewater

Plasma at the Nanoscale: A volume in Micro and Nano Technologies

International audiencePlasma technology can facilitate the fabrication of nanomaterials and nanoscale structures. On the other hand, nanotechnology could be possibly used in plasma science. Several advanced nanomaterials and nanodevices could be used to fabricate nanoplasma (nanoscale plasma), such as nanoelectrodes, nanoantennae, nanolasers, nanoreactors, nanomagnets, nanosensors, nanobatteries, nanogenerator and supercapacitors.This book provides information on fundamental design concepts and promising applications of nanoplasma. It explains how, for the next generation of electronic devices with high data rate communications, a high-speed operation of electronic switches could be attained using nanoplasma. Similarly, in the field of heath and aesthetics, nanoplasma can be used as a non-surgical localized treatments for the face and neck, such as eyelid correction. In addition, various kinds of advanced nanostructures can be fabricated using the plasma technolog

Photocatalytic Treatment of Wastewater Containing Simultaneous Organic and Inorganic Pollution: Competition and Operating Parameters Effects

International audienceIn the present study, methylene blue (MB) removal from aqueous solutions via the photocatalytic process using TiO2 as a catalyst in the presence of external ultra-violet light (UV) was investigated. The results of adsorption in the absence of UV radiation showed that adsorption reached an equilibrium state at 60 min. The experimental kinetic data were found to be well fitted by the pseudo-second-order model. Furthermore, the isotherm study suggested that dye uptake by TiO2 is a chemisorption process with a maximum retention capacity of 34.0 mg/g. The photodegradation of MB was then assessed under various experimental conditions. The related data showed that dye mineralization decreased when dye concentrations were increased and was favored at high pH values and low salt concentrations. The simultaneous presence of organic and inorganic pollution (Zinc) was also evaluated. The effect of the molar ratio Zn2+/MB+ in the solution at different pH values and NaCl concentrations was also monitored. The corresponding experimental results showed that at low values of Zn2+ in the solution (30 mg/L), the kinetic of the MB removal became faster until reaching an optimum at Zn2+/MB+ concentrations of 60/60 mg/L; it then slowed down for higher concentrations. The solutions' carbon contents were measured during the degradation process and showed total mineralization after about 5 h for the optimal Zn2+/MB+ condition

Reactive species monitoring and their contribution for removal of textile effluent with photocatalysis under UV and visible lights: Dynamics and mechanism

In this study, the photocatalytic activities were investigated for the treatment of Reactive Green 12 (RG 12) solution under UV and visible irradiation using Cu doped TiO2, and TiO2 impregnated on (1) cellulose and (2) UV-C activated polyester catalysts. The obtained results revealed that TiO2 impregnated on UV-C activated polyester showed promising performances compared to the other synthesized catalysts. Moreover, the dispersion of active sites on UV-C pretreated polyester was optimized and tested for RG 12 removal in the binary mixture, the presence of Direct Red 89 (DR 89) dye had an inhibiting effect on the rate of RG 12 discoloration process because of the competitive effect between dyes molecules toward the available active sites. The role and contribution of reactive oxidizing species (ROS): center dot OH, O-2 center dot(-) and h(+) was also examined with the two catalysts under different light sources; it was found that the superoxide radical anion played the key role in RG 12 photocatalytic degradation for both TiO2 supported catalysts. Nevertheless, the behavior of O-2 center dot(-) radicals was found to be changed from promoting effect to inhibitory effect when changing light from UV to Visible