Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

Selective gas adsorption and separation in metal–organic frameworks

1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inﬂammation, Apoptose, etc.)20866.2.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13

In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28

Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37



Figure 1

Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.



In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.

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Gold nanoparticles in chemical and biological sensing.

Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

Lanthanide-based luminescent hybrid materials.

The invention relates to a method for preparing a sol-gel solution which can be used for preparing a barium titanate ceramic doped with hafnium and/or with at least one lanthanide element, including the following steps: a) a step of placing a first mixture including a barium carboxylate and a diol solvent in contact with a second mixture including a titanium alkoxide and a hafnium alkoxide and/or an alkoxide of a lanthanide element in a monoalcohol solvent; b) a step of distilling the mixture resulting from step a), with a view to removing at least some of the monoalcohol solvent; and c) a step of adding, under heat, acetic acid to the distilled mixture from step b).

Method for preparing a sol-gel solution which can be used for preparing a barium titanate ceramic doped with hafnium and/or with at least one lanthanide element

L'invention a trait a un procede de preparation d'un materiau a base de ceramique(s) oxyde(s) piezoelectrique(s) comprenant les etapes 5 suivantes : a) deposer par voie liquide sur au moins une face d'un substrat une couche d'une dispersion comprenant une poudre d'une ceramique oxyde piezoelectrique et une solution sol-gel precurseur 10 d'une ceramique oxyde identique ou differente de la ceramique oxyde piezoelectrique constitutif de la poudre, b) repeter a), une ou plusieurs fois, de maniere a obtenir un empilement d'au moins deux 15 couches ; c) traiter thermiquement lesdites couches en vue de les transformer en la (les) ceramique(s) correspondante(s) ; d) impregner par trempage-retrait 20 l'empilement obtenu en c) par une solution sol-gel identique a celle utilisee dans l'etape a) ; e) repeter eventuellement l'etape d) une ou plusieurs fois ; f) traiter thermiquement ledit empilement, 25 en vue de transformer la solution sol-gel impregnant l'empilement en la ceramique piezoelectrique correspondante.

Procede de preparation de materiaux piezoelectriques

The invention relates to a method for preparing sols of metal oxides, with an aqueous component, which are stable over time and which notably allow the making of thin films having both remarkable optical and abrasion resistance properties. This method comprises: (i) replacing with water all or part of the alcohol or of the alcohols present in an alcoholic sol of a metal oxide, with a neutral or basic pH, and optionally (ii) adjusting the pH of the thereby obtained aqueous or partly aqueous sol to a value of at least 8. The invention also relates to a method for making films from these sols and, in particular, thin films with optical properties and resistant to abrasion. Applications: making optical components for power lasers, making optical fibers, cathodic tubes, etc.

Preparation of stable metal oxide sols, notably for making thin abrasion-resistant films with optical properties

The invention relates to a process for preparing metal oxide sols, having an aqueous component, which are stable over time and which make it possible, in particular, to manufacture thin films having both remarkable optical and abrasion-resistance properties. This process comprises: (i) replacing all or some of the alcohol or alcohols present in an alcoholic sol of a metal oxide, of neutral or basic pH, with water and optionally (ii) adjusting the pH of the aqueous or partially aqueous sol thus obtained to a value of at least 8. The invention also relates to a process for manufacturing films from these sols and, in particular, thin films having optical and abrasion-resistant properties. Applications: manufacture of optical components for high-power lasers, manufacture of optical fibres, cathode ray tubes, etc.

Preparation of stable metal oxide sols, of use in particular for the manufacture of thin films having optical and abrasion-resistant properties

The hybrid material comprises two phases, a primary mineral phase consisting of an open-pore mesoporous structure and a secondary phase comprising an organic polymer. Independent claims are also included for: (1) the preparation of the material; and (2) membranes or electrodes constructed from the material.

Hybrid organic/inorganic material, useful for the preparation of a membrane or electrode suitable for use in a fuel cell, comprises a mesoporous inorganic phase and an organic phase

Philippe Belleville

Papers

Method for preparing a sol-gel solution which can be used for preparing a barium titanate ceramic doped with hafnium and/or with at least one lanthanide element

Procede de preparation de materiaux piezoelectriques

Preparation of stable metal oxide sols, notably for making thin abrasion-resistant films with optical properties

Preparation of stable metal oxide sols, of use in particular for the manufacture of thin films having optical and abrasion-resistant properties

Hybrid organic/inorganic material, useful for the preparation of a membrane or electrode suitable for use in a fuel cell, comprises a mesoporous inorganic phase and an organic phase