High Productive Chromatographic Methods for Determination of the Total and Active Surface Area of Catalysts

Karnaukhov, A.P.; Buyanova, N. E.

doi:10.1016/b978-0-408-70077-1.50019-1

Cited by 1 publication

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“…The average current size of nanoparticles was estimated based on their surface area, all particles were assumed to be spherical. The surface area was determined based on the argon adsorption by the gas-chromatographic method [ 21 ].…”

Section: Methodsmentioning

confidence: 99%

Cryochemical Synthesis of Polymorphous Nanostructures of a Steroid Neurohormone

et al. 2017

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A new cryochemical strategy of producing nanoparticles and polymorphous nanostructures of drugs is used, which is based on the dynamic combination of high and low temperatures, gas and solid phases, and inert carrier gases. This technology is applied to the synthesis of nanoparticles of steroid neurohormone dehydroepiandrosterone (DHEA). We have optimized the conditions of synthesis of the new polymorphous DHEA structure, FVII. The molecules of DHEA in FVII structure are bound by hydrogen bonds via oxygen atoms. The grain size is 100 nm. It is shown that the yield and ratio of the resulting nanoforms of this hormone are determined by the nature and properties of the inert carrier gas. The highest yield and selectivity of FVII are observed when carbon dioxide is used as the carrier gas. In the case of helium, the FVII content decreases from 85 to 30% and other structures are formed. In experiments without carrier gas, nanoparticles are formed but no FVII is produced. The selectivity and the effect of carrier gas are considered on the basis of homogeneous and heterogeneous formation of nanoparticles and the relationship between particle selectivity and its activity. The synthesis of various polymorphous structures on the nanoscale is assumed to be the manifestation of the size effect in the synthesis of drugs.

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Section: Methodsmentioning

confidence: 99%