Synthesis of BaCO 3 particles tailored by carboxylated cellulose fibers

The present work deals with the use of carboxylated cellulose fibers, thereafter called Cellulose Nano Fibers (CNF), as eco-friendly materials and sustainable resources for remediation and valuation, of metal ions present in contaminated water. Barium divalent cation (Ba2+) is among the most common heavy metal pollutants found in water such as arsenic, cadmium, chromium, copper, nickel, lead and mercury. Thus, CNFs containing carboxylate groups were first prepared by the oxidation of the cellulose fibers using the NaOCl-NaBr-TEMPO system, and thereafter, they were used as adsorbent for Ba2+ ions removal from BaCl2 aqueous solutions. Such Ba2+ removal was evidenced by the decrease of both the CNF surface charge and the CNF absorbance, upon the addition of the metal divalent cation, BaCl2 to the CNF aqueous dispersions. It is shown that the interaction occurring between the fiber carboxylic groups and the positively charged metal ions, Ba2+, occurs via electrostatic interactions and leads to the CNFs –Ba2+ complex formation. In the second part of this work, we investigated the effect of the CNFs on the crystallogenesis of barium carbonate particles, BaCO3. Thus, the CNFs aqueous solution was first added to barium chloride BaCl2 solution, and the mixture was stirred for a period of time (complexation time), prior the addition of sodium carbonate (Na2CO3) solution. The precipitation of barium carbonate particles in the presence of CNFs occurred at ambient temperature, in a water-jacketed Pyrex glass vessel. Finally, the resulting Barium carbonate-CNFs composites were examined by various methods such as Scanning Electronic Microscopy (SEM), and X-ray Diffraction. From the SEM data, two BaCO3 morphologies were observed, dendritic and bent or rods particles, respectively, in the absence and in the presence of the CNFs

Testing and performance analysis of a hollow fiber-based core for evaporative cooling and liquid desiccant dehumidification

In this study, an innovative heat and mass transfer core is proposed to provide thermal comfort and humidity control using a hollow fiber contactor with multiple bundles of micro-porous hollow fibers. The hollow fiber-based core utilizes 12 bundles aligned vertically, each with 1,000 packed polypropylene hollow fibers. The proposed core was developed and tested under various operating and ambient conditions as a cooling core for a compact evaporative cooling unit and a dehumidification core for a liquid desiccant dehumidification unit. As a cooling core, the fiber-based evaporative cooler provides a maximum cooling capacity of 502 W with a wet bulb effectiveness of 85%. As a dehumidification core and employing potassium formate as a liquid desiccant, the dehumidifier is capable of reducing the air relative humidity by 17% with an overall dehumidification capacity of 733 W and humidity effectiveness of 47%. Being cheap and simple to design with their attractive heat and mass transfer characteristics and the corresponding large surface area-to-volume ratio, hollow fiber membrane contactors provide a promising alternative for cooling and dehumidification applications

Plasmon-based photopolymerization: near-field probing, advanced photonic nanostructures and nanophotochemistry

Cataloged from PDF version of article.Hybrid nanomaterials are targeted by a rapidly growing group of nanooptics researchers, due to the promise of optical behavior that is difficult or even impossible to create with nanostructures of homogeneous composition. Examples of important areas of interest include coherent coupling, Fano resonances, optical gain, solar energy conversion, photocatalysis, and nonlinear optical interactions. In addition to the coupling interactions, the strong dependence of optical resonances and damping on the size, shape, and composition of the building blocks provides promise that the coupling interactions of hybrid nanomaterials can be controlled and manipulated for a desired outcome. Great challenges remain in reliably synthesizing and characterizing hybrid nanomaterials for nanooptics. In this review, we describe the synthesis, characterization, and applications of hybrid nanomaterials created through plasmon-induced photopolymerization. The work is placed within the broader context of hybrid nanomaterials involving plasmonic metal nanoparticles and molecular materials placed within the length scale of the evanescent field from the metal surface. We specifically review three important applications of free radical photopolymerization to create hybrid nanoparticles: local field probing, photoinduced synthesis of advanced hybrid nanoparticles, and nanophotochemistry

Advanced Large-Scale Nanofabrication Route for Ultrasensitive SERS Platforms Based on Precisely Shaped Gold Nanostructures

One of the key issues for SERS-based trace applications is engineering structurally uniform substrates with ultrasensitivity, stability, and good reproducibility. A label-free, cost-effective, and reproducible fabrication strategy of ultrasensitive SERS sensors was reported in this work. Herein, we present recent progress in self-assembly-based synthesis to elaborate precisely shaped and abundant gold nanoparticles in a large area. We demonstrated that shape control is driven by the selective adsorption of a cation (Na+, K+, and H+) on a single facet of gold nanocrystal seeds during the growth process. We studied SERS features as a function of morphology. Importantly, we found a correlation between the shape and experimental SERS enhancement factors. We observed a detection threshold of 10−20 M of bipyridine ethylene (BPE), which matches the lowest value determined in literature for BPE until now. Such novel sensing finding could be very promising for diseases and pathogen detection and opens up an avenue toward predicting which other morphologies could offer improved sensitivity. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was funded by C2MP doctoral school and FEDER “Fond Européen de Développement Regional” and “Région Grand-Est” are acknowledged for their financial support (Pronano project)

Stochastic DEA

International audienceData Envelopment Analysis (DEA) was introduced as a linear programming model by Charnes et al. (Eur J Oper Res 2:429\textendash444, 1978) and Banker et al. (Manag Sci 30:1078\textendash1092, 1984) as a nonparametric model to estimate frontier production and technical efficiency using linear programming. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG

Surface modifications induced by the friction of graphites against steel

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Tribological behaviour of graphite powders at nano- and macroscopic scales

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Oriented crystallization of isotactic polystyrene in films prepared by friction transfer

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