Search results for "Chemical engineering"
showing 10 items of 5892 documents
Organic synthesis of high added value molecules with MOF catalysts
2020
Recent examples of organic synthesis of fine chemicals and pharmaceuticals in confined spaces of MOFs are highlighted and compared with silica-based ordered porous solids, such as zeolites or mesoporous (organo)silica. These heterogeneous catalysts offer the possibility of stabilizing the desired transition states and/or intermediates during organic transformations of functional groups and (C-C/C-N) bond forming steps towards the desired functional high added value molecular scaffolds. A short introduction on zeolites, mesoporous silica and metal-organic frameworks is followed by relevant applications in which confined active sites in the pores promote single or multi-step organic synthesis…
Hierarchical Mass Transfer Analysis of Drug Particle Dissolution, Highlighting the Hydrodynamics, pH, Particle Size, and Buffer Effects for the Disso…
2020
Dissolution is a crucial process for the oral delivery of drug products. Before being absorbed through epithelial cell membranes to reach the systemic circulation, drugs must first dissolve in the human gastrointestinal (GI) tract. In vivo and in vitro dissolutions are complex because of their dependency upon the drug physicochemical properties, drug product, and GI physiological properties. However, an understanding of this process is critical for the development of robust drug products. To enhance our understanding of in vivo and in vitro dissolutions, a hierarchical mass transfer (HMT) model was developed that considers the drug properties, GI fluid properties, and fluid hydrodynamics. T…
Impact of uncharged and charged stabilizers on in vitro drug performances of clarithromycin nanocrystals
2018
The purpose of this study was to evaluate the effect of charge on the in vitro drug performances of clarithromycin nanocrystals. To prepare different charges of nanocrystals, media milling was employed with the use of different stabilizing systems. The uncharged nanocrystals were prepared from poloxamer 407. The negatively and positively charged nanocrystals were stabilized using a combination of poloxamer 407 with sodium lauryl sulfate (SLS) and cetyltrimethylammonium bromide (CTAB), respectively. After production, the particle size of the negatively and positively charged nanocrystals was smaller than that of the uncharged one. The similar particle size of variously charged clarithromycin…
Formulation strategy towards minimizing viscosity mediated negative food effect on disintegration and dissolution of immediate release tablets.
2017
Food induced viscosity can delay disintegration and subsequent release of API from solid dosage form which may lead to severe reduction in the bioavailability of BCS type III compounds. Formulations of such tablets need to be optimized in view of this postprandial viscosity factor. In this study, three super disintegrants, croscarmellose sodium (CCS), cross-linked polyvinylpolypyrrolidone (CPD), and sodium starch glycolate (SSG) were assessed for their efficiency under simulated fed state. Tablets containing these disintegrants were compressed at 10 and 30 KN, while taking lactose as a soluble filler. In addition to other compendial tests, disintegration force of these formulations was meas…
A monolayer of a Cu2+-tetraazamacrocyclic complex on glass as the adhesive layer for silver nanoparticles grafting, in the preparation of surface-act…
2011
International audience; A silane-derivatized tetraaza Cu2+ macrocyclic complex is prepared, which forms monolayers on glass surfaces, capable of allowing the further deposition of a stable monolayer of silver nanoparticles, obtaining by this, surfaces that display an enhanced antibacterial activity against Staphylococcus aureus and Escherichia coli.
Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications
2018
Investigation on Ash Slagging Characteristics During Combustion of Biomass Pellets and Effect of Additives
2017
This study reports a systematic investigation into ash slagging behavior during combustion of barley straw and barley husk pellets with or without additives in a residential pellet burner. The slagging tendencies of the pellets were evaluated based on the amount, chemistry, mineralogy, and morphology of inlet ash formed as slag and sintering degrees of residual ash. The barley straw and husk pellets showed high slagging tendencies with 39 and 54 wt % ingoing ash formed as slag. Analyses using X-ray fluorescence and scanning electron microcopy combined with energy-dispersive X-ray spectroscopy revealed high concentrations of K, Si, and Ca but a minor amount of P in barley straw slag. The sla…
Atmospheric analytical chemistry.
2011
Green analytical chemistry
2010
Self-assembly in surfactant-based liquid mixtures: Bis(2-ethylhexyl)phosphoric acid/bis(2-ethylhexyl)amine systems
2010
Surfactant-based liquid mixtures constitute an interesting class of nanostructured materials with promising potential in specialized applications. Here, structural and conductometric properties of liquid mixtures composed of bis(2-ethylhexyl)amine (BEEA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) have been thoroughly investigated with the aim to correlate structural features with system charge transport capability. The evolution of self-assembled local nanostructures with system composition has been investigated by FT-IR and XRD while the conductometric properties were probed by conventional AC complex impedance. Both pure components exhibit nano-segregation due to their amphiphilic natur…