The effects of adding Nano-Silica particles on the compressive strength and water permeability of concrete and its comparison with that of Micro-Silica were investigated in this work. The effect of combination of Nano- silica and Micro-silica were also studied in this work, which resulted in an increase in compressive strength of concrete in comparison with other concrete specimens tested in th...

Diatoms are eukaryotic microalgae that produce species-specifically structured cell walls made of SiO(2) (silica). Formation of the intricate silica structures of diatoms is regarded as a paradigm for biomolecule-controlled self-assembly of three-dimensional, nano- to microscale-patterned inorganic materials. Silica formation involves long-chain polyamines and phosphoproteins (silaffins and sil...

We have investigated the thermodynamics of sulfuric acid dimer hydration using ab initio quantum mechanical methods. For (H(2)SO(4))(2)(H(2)O)(n) where n = 0-6, we employed high-level ab initio calculations to locate the most stable minima for each cluster size. The results presented herein yield a detailed understanding of the first deprotonation of sulfuric acid as a function of temperature f...

Data from exposure of experimental animals and human subjects to sulfuric acid presents a consistent picture of its toxicology. Effects on airway resistance in asthmatic subjects were well predicted by data obtained on guinea pigs. Sulfuric acid increases the irritant response to ozone in both rats and man. In donkeys, rabbits, and human subjects, sulfuric acid alters clearance of particles fro...

To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air ...

Strong inorganic acid mists containing sulfuric acid are known to be human carcinogens based on sufficient evidence of carcinogenicity from studies in humans that indicate a causal relationship between exposure to strong inorganic acid mists containing sulfuric acid and human cancer. Occupational exposures to strong inorganic acid mists containing sulfuric acid are specifically associated with ...

Sulfuric acid hydrate has been proposed as an important species on Europa’s surface, the acid being produced by radiolysis of surficial sulfur compounds. We investigated the spectral properties of disordered and crystalline forms of sulfuric acid and suggest that the hydration properties of Europa’s hypothesized sulfuric acid lie between two end members: liquid sulfuric acid and its higher crys...

The effects of adding Nano-Silica particles on the compressive strength and water permeability of concrete and its comparison with that of Micro-Silica were investigated in this work. The effect of combination of Nano- silica and Micro-silica were also studied in this work, which resulted in an increase in compressive strength of concrete in comparison with other concrete specimens tested in th...

in recent years, using sol-gel procedure for the purpose of laboratory and industrial synthesis of nano-structures, and especially silica nano-particles, has been significantly increased. in this research, silica particles were synthesized by sol-gel procedure and their physical and chemical properties were studied by means of scanning electron microscopy (sem), transmission electron microscopy...

Abstract Synthesis of rice husk nanosilica was carried out using hydrothermal methods at various temperatures and times their characteristics. The stages synthesis include sample preparation, synthesis, reaction temperature variations used are 120°C, 150°C, 180°C, the time is 2 hours, 4 6 hours then titrated sulfuric acid until it reaches pH 7-8. XRF analysis results showed silica (SiO2) conten...