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 of preparing a stable oxide ceramic precursor sol-gel solution based on lead, titanium, zirconium and lanthanide(s). The invention comprises the following successive steps consisting in: a) preparing a sol-gel solution by bringing a molecular lead precursor, a molecular titanium precursor, a molecular zirconium precursor and a molecular lanthanide precursor into contact with a medium comprising a diol solvent and optionally an aliphatic monoalcohol; b) leaving the solution thus obtained to stand for a sufficient period of time in order to obtain a solution having an essentially-constant viscosity; and c) diluting the solution obtained in the preceding step with a diol solvent identical to that used in step a or a solvent that is miscible with said solvent, at a predetermined rate. The invention can be used to prepare an oxide ceramic material comprising lead, a lanthanide metal, titanium and zirconium.

Method of preparing oxide ceramic based on lead, titanium, zirconium and lanthanide(s)

The invention concerns a method for making conformable ceramic oxide layers on substrates having raised designs including: a step of depositing on said substrate a layer of sol-gel solution precursor of said ceramics; a step of heat treatment of said layer to transform same into ceramics; said steps being optionally repeated one or more times The invention is characterized in that the sol-gel solution precursor of said ceramics is prepared by a method including the following successive steps: a) preparing a first solution by contacting one or more molecular precursors of metals designed to be constituents of the ceramics in a medium comprising a diol solvent and optionally an aliphatic monoalcohol; b) allowing the solution obtained in a) to rest during sufficient time required to obtain a solution having a substantially constant viscosity; c) diluting at a predetermined proportion the solution obtained in b) with a diol solvent optionally identical to the one in step a) or a solvent miscible with the diol solvent used in step a)

Method for producing a ceramic oxide based coating conformable with the geometry of a substrate having raised designs

The invention concerns a method for preparing a material based on piezoelectric ceramic oxide(s) comprising the following steps: a) wet deposition on at least one surface of a substrate of a layer of a dispersion comprising a piezoelectric ceramic oxide powder and a piezoelectric ceramic oxide precursor sol-gel solution identical to or different from the piezoelectric oxide constituting the powder; b) repeating a) once or several times, so as to obtain a stack of at least two layers; c) heat-treating said layers so as to transform them into corresponding ceramics; d) wet-shrink impregnation of the stack obtained at c) with a sol-gel solution identical to the one used in step a); e) optionally repeating step d) once or several times; f) heat-treating said stack, so as to transform the sol-gel impregnating the stack into the corresponding piezoelectric ceramics.

Method for preparing piezoelectric materials

The preparation of a stable sol-gel solution precursor of a ceramic oxide comprises: (A) preparing a sol-gel solution from molecular precursors of lead, titanium, zirconium and a metal lanthanide with a diol solvent and possibly an aliphatic mono-alcohol; (B) resting the solution for sufficient time to obtain an essentially constant viscosity; and (C) diluting the solution to a determined level with an identical diol solvent or a miscible solvent. Independent claims are also included for: (A) the sol-gel solution obtained from this method of preparation; (B) the preparation of a ceramic material using the sol-gel solution; and (C) the ceramic oxide material produced.

Preparation of a stable sol-gel solution precursor of a ceramic oxide containing lead, titanium, zirconium and a metal lanthanide for electronic applications calling for a high dielectric constant

L'invention se rapporte a un procede de preparation de sols d'oxydes metalliques, a composante aqueuse, qui sont stables dans le temps et qui permettent notamment de fabriquer des films minces presentant a la fois des proprietes optiques et de resistance a l'abrasion remarquables. Ce procede comprend : (i) le remplacement par de l'eau de tout ou partie de l'alcool ou des alcools presents dans un sol alcoolique d'un oxyde metallique, de pH neutre ou basique, et eventuellement (ii) l'ajustement du pH du sol aqueux ou partiellement aqueux ainsi obtenu a une valeur d'au moins 8. L'invention se rapporte egalement a un procede de fabrication de films a partir de ces sols et, en particulier de films minces a proprietes optiques et resistants a l'abrasion. Applications : fabrication de composants optiques pour lasers de puissance, fabrication de fibres optiques, de tubes cathodiques, etc.

Preparation de sols d'oxydes metalliques stables, utiles notamment pour la fabrication de films minces a proprietes optiques et resistants a l'abrasion

Philippe Belleville

Papers

Method of preparing oxide ceramic based on lead, titanium, zirconium and lanthanide(s)

Method for producing a ceramic oxide based coating conformable with the geometry of a substrate having raised designs

Method for preparing piezoelectric materials

Preparation of a stable sol-gel solution precursor of a ceramic oxide containing lead, titanium, zirconium and a metal lanthanide for electronic applications calling for a high dielectric constant

Preparation de sols d'oxydes metalliques stables, utiles notamment pour la fabrication de films minces a proprietes optiques et resistants a l'abrasion