The present invention relates to hollow silica particles, which each includes a shell layer containing silica and a space inside the shell layer, in which the hollow silica particles have a peak intensity derived from SiOH at a wavenumber of around 3,746 cm.sup.−1 of 0.60 or less by infrared spectroscopy, a relative permittivity at 1 GHz of from 1.3 to 5.0 and a dielectric loss tangent at 1 GHz of from 0.0001 to 0.05.

Methods of forming cement pastes, methods of forming concrete, and methods of forming other compositions using mineral particles formed from the one or more of biomineralizing microorganisms and biomineralizing microorganisms. Desired features, such as size and morphology, can be controlled by controlling growth parameters of the biomineralizing microorganisms and biomineralizing microorganisms.

A preparation method for a spherical silica powder filler comprises the following steps: S1, providing spherical polysiloxane comprising a T unit by means of a hydrolysis condensation reaction of R.sub.1SiX.sub.3, wherein R.sub.1 is hydrogen atom or an organic group having independently selectable 1 to 18 carbon atoms, X is a hydrolyzable group, and T unit is R.sub.1SiO.sub.3—; and S2, calcining the spherical polysiloxane under the condition of a dry oxidizing gas atmosphere, the calcining temperature being between 850° C. and 1200° C., so as to obtain the spherical silica powder filler which does not contain silica particles of which the diameter is less than 50 nanometers. The spherical silica powder filler does not contain silica particles of which the diameter is less than 50 nanometers, has a low dielectric loss and a low thermal expansion coefficient, and is suitable for high-frequency high-speed circuit boards, prepregs or copper clad laminates, etc.

Provided is a silica that exhibits a high matting property when utilized as a matting agent for a paint, and can also suppress the occurrence of cloudiness. The silica has an aggregated structure in which primary particles are aggregated, has a particle diameter ratio R represented by the following equation (1) of from 4.3 to 5.2, has an absorbance of 0.6 or less for light having a wavelength of 700 nm as an aqueous dispersion having a concentration of 1.48 mass %, and has a particle density measured with a He pycnometer of 2.18 g/cm.sup.3 or more: Equation (1) R=.sup.LD50/.sup.CD50 (in the equation (1), .sup.LD50 represents a volume-based 50% cumulative particle diameter (μm) of the silica measured based on a laser diffraction/scattering method, and .sup.CD50 represents a volume-based 50% cumulative particle diameter (μm) of the silica measured based on a Coulter counter method).

The present invention relates to a method of preparing a high hydrophobic silica aerogel having a low tap density and a hydrophobic silica aerogel prepared thereby. The method of preparing a hydrophobic silica aerogel according to the present invention may have good productivity and economic efficiency, because preparation time is reduced by simultaneously performing surface modification and solvent substitution in a single step, and may control a degree of hydrophobicity of the prepared silica aerogel by controlling a surface modification reaction by including a step of adding ammonium hydroxide. Thus, a hydrophobic silica aerogel having excellent physical properties, such as tap density and specific surface area, as well as high hydrophobicity obtained by controlling the degree of hydrophobicity may be prepared.

The present invention provides highly dispersible precipitated silica having improved structure and properties for use as reinforcing filler in elastomeric compositions and method of preparation thereof. The present invention further provides an alkaline silicate solution having reduced dielectric constant by digesting biogenic silica source with alkaline solution such that soluble organic compounds present in the biogenic silica source leach into the alkaline silicate solution. The alkaline silicate solution obtained as above is then acidified with a mineral acid under particular conditions of pH, temperature, time etc. to obtain the highly dispersible precipitated silica of the present invention.

Disclosed in certain embodiments is a method of preparing structural colorants comprising photonic particles, the method comprising varying the calcination temperature in the process to enable the tuning of pore size to obtain a wide variety of possible colors.

Provided are porous spherical silica particles whose oil absorption is suppressed while the porous spherical silica particles have a large specific surface area; and a method for manufacturing such spherical silica particles.

According to the present invention, provided are spherical silica particles whose specific surface area obtained by employing a BET method is 300 m.sup.2/g or more, total pore volume is 0.3 ml/g or less, and oil absorption is 50 ml/100 g or less, the spherical silica particles obtained by subjecting silica gel particles obtained by employing a sol-gel method, for example, in which an alkali silicate is emulsified and coagulated, to only drying at a low temperature without subjecting the silica gel particles to calcination at a high temperature; and a method for manufacturing such spherical silica particles.

Disclosed in certain embodiments are hybrid metal oxide particles and methods of preparing the same. In at least one embodiment, hybrid metal oxide particles comprise a continuous matrix of a first metal oxide having embedded therein an array of metal oxide particles comprising a second metal oxide. In at least one embodiment, the hybrid metal oxide particles are substantially non-porous.

A composite polyvinyl alcohol (PVA) preservative film, a preparation method and an application thereof are provided. The film includes PVA of 9-12 parts, modified silicon dioxide nanoparticles of 2-5 parts, antimicrobial of 0.3-2 parts and deionized water of 100 parts. Fruits and vegetables sensitive to sunlight have lower requirements for illumination while preserving. With PVA as matrix and silicon dioxide (SiO.sub.2) nanoparticles as modified materials, composite PVA is obtained by controlling a particle size of SiO.sub.2 and modifying its surface. The composite PVA preservative film takes advantages of different refractive indexes between PVA and SiO.sub.2 and controlling the particle size of SiO.sub.2, thereby having a low luminous transmittance. The preservative film has an effect of light-proof on fruits and vegetables suitable for light-proof storage, and improves its gas transmission and water resistance because of adding SiO.sub.2, thereby facilitating packaging preservation of the fruits and vegetables.