Silica aerogels are among the lightest weight solid materials and exhibit other unique properties, in particular an outstanding insulation performance. However, these nanostructured highly porous materials show inherent brittleness that makes their processing and handling difficult and constrains their use in common daily applications. One of the most convincing and effective strategies to reinforce the silica aerogel structure is the manufacturing of aerogel composites with embedded fibres, which significantly contributes to widening their applications. This review encompasses a complete survey on scientific achievements related to silica aerogel composites reinforced with all types of fibres (natural, man-made, organic, inorganic and nanofibres), describing their synthesis approaches and properties. The influence of the embedment of different fibres on the final properties of the composites is thoroughly reported, considering their amount in the matrix and/or their specific characteristics, namely morphology, orientation and optical features. The applications linked to the fibre-reinforced silica aerogel composites are briefly addressed as well, evincing developments in typical functions of aerogels, as thermal and/or acoustic insulators and adsorbents, and also in emerging uses, for example as sensors or technical and protective apparel.

Silica aerogel composites with embedded fibres: a review on their preparation, properties and applications

Terbuthylazine and desethylterbuthylazine: Recent occurrence, mobility and removal techniques

We theoretically investigate the propagation of bright spatial solitary waves in highly nonlocal media possessing radial symmetry in a three-dimensional cylindrical geometry. Focusing on a thermal nonlinearity, modeled by a Poisson equation, we show how the profile of the light-induced waveguide strongly depends on the extension of the nonlinear medium in the propagation direction as compared to the beamwidth. We demonstrate that self-trapped beams undergo oscillations in size, either periodically or aperiodically, depending on the input waist and power. The---usually neglected---role of the longitudinal nonlocality as well as the detrimental effect of absorptive losses are addressed.

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Spatial optical solitons in highly nonlocal media

More than thirty years ago Glauber suggested that the link between the reversible microscopic and the irreversible macroscopic world can be formulated in physical terms through an inverted harmonic oscillator describing quantum amplifiers. Further theoretical studies have shown that the paradigm for irreversibility is indeed the reversed harmonic oscillator. As outlined by Glauber, providing experimental evidence of these idealized physical systems could open the way to a variety of fundamental studies, for example to simulate irreversible quantum dynamics and explain the arrow of time. However, supporting experimental evidence of reversed quantized oscillators is lacking. We report the direct observation of exploding n = 0 and n = 2 discrete states and Γ0 and Γ2 quantized decay rates of a reversed harmonic oscillator generated by an optical photothermal nonlinearity. Our results give experimental validation to the main prediction of irreversible quantum mechanics, that is, the existence of states with quantized decay rates. Our results also provide a novel perspective to optical shock-waves, potentially useful for applications as lasers, optical amplifiers, white-light and X-ray generation.

/pdf/physical-realization-of-the-glauber-quantum-oscillator-1adpv1rrfc.pdf

Physical realization of the Glauber quantum oscillator.

Surfactant-free synthesis of silica aerogel microspheres with hierarchically porous structure

Silica aerogels are materials well suited for high power nonlinear optical applications. In such regime, the non-trivial thermal properties may give rise to the generation of optical shock waves, which are also affected by the structural disorder due to the porous solid-state gel. Here we report on an experimental investigation in terms of beam waist and input power, and identify various regimes of the generation of wave-breaking phenomena in silica aerogels.

https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/4490/Gentilinietal_oe_22_2_1667.pdf;sequence=1

Optical shock waves in silica aerogel

Very few studies have investigated the adsorption performance of hydrophobic and hydrophilic silicas with dissolved organics in water, which is a required final step during produced water treatment ...

https://journals.sagepub.com/doi/pdf/10.1177/0263617417692339

Novel hydrophilic and hydrophobic amorphous silica: Characterization and adsorption of aqueous phase organic compounds:

Synthetic amorphous silicas with high porosity (94–97%) are introduced and various pathways for their synthesis are presented. The materials have structures with high surface area (300–750 m2/g) an ...

Case study of a green nanoporous material from synthesis to commercialisation: Quartzene®

The adsorption capacities of a novel amorphous silica, and silica xerogels, for aromatic compounds were investigated using Micro Column Rapid Breakthrough tests coupled with Sequential Injection Fl ...

/pdf/organics-adsorption-on-novel-amorphous-silica-and-silica-5f8f906yda.pdf

Organics adsorption on novel amorphous silica and silica xerogels: microcolumn rapid breakthrough test coupled with sequential injection analysis

A filter apparatus (11) for removing dissolved organic compounds from a water based liquid, comprising at least one filter unit (12, 20) in the form of a container (13, 21) in which an inlet (14, 22, 23) and an outlet (16, 17, 24) is provided, a filter bed (25) being arranged in the at least one container between the inlet and the outlet, the filter bed comprising at least one layer of an adsorbent comprising an amorphous precipitated silica material, wherein the amorphous precipitated silica material has a porosity with an average pore width of less than 10 nm.

Farnaz Ghajeri

Papers

Optical shock waves in silica aerogel

Novel hydrophilic and hydrophobic amorphous silica: Characterization and adsorption of aqueous phase organic compounds:

Case study of a green nanoporous material from synthesis to commercialisation: Quartzene®

Organics adsorption on novel amorphous silica and silica xerogels: microcolumn rapid breakthrough test coupled with sequential injection analysis

A filter apparatus and a method for removing dissolved organic compounds from a water based liquid