Summary
Capturing water vapor from atmospheric air is a possible solution to local water scarcity, but it is very energy demanding. Energy consumption estimates of water-from-air technologies involving adsorption processes, thermo-responsive hydrophilicity switching polymers, air cooling processes, and reverse osmosis of deliquescent salt solutions reveal that these technologies are not competitive when compared with seawater desalination, and the use of fresh water and wastewater sources. They only become a viable option in the absence of local liquid water sources and when long-distance transport for socio-economic reasons is not an option. Of interest, direct solar-driven technology for water-from-air production is an attractive means to disentangle the local water-energy nexus. It is expected that climate change will accelerate the introduction of water-from-air technologies in local water supply schemes. The optimal water-from-air technology depends on the climate, relative humidity, and temperature profiles. A world map is presented, indicating the optimal geographic location for each technology.
Porous silica is used as a drug delivery
agent to improve the bioavailability
of sparsely soluble compounds. In this approach, the active pharmaceutical
ingredient (API) is commonly loaded into the porous silica by incipient
wetness impregnation using organic solvents. Subsequent solvent elimination
is critical as the residual solvent concentration cannot exceed threshold
values set by health and safety regulations (e.g., EMA/CHMP/ICH/82260/2006).
For dichloromethane and methanol, for example, residual concentrations
must be below 600 and 3000 ppm, respectively. Today, EU and USA Pharmacopoeias
recommend tedious procedures for residual solvent quantification,
requiring extraction of the solvent and subsequent quantification
using capillary gas chromatography with static headspace sampling
(sHS-GC). This work presents a new method based on the combination
of standard addition and absolute quantification using magic-angle
spinning nuclear magnetic resonance spectroscopy (MAS qNMR). The methodology
was originally developed for absolute quantification of water in zeolites
and has now been validated for quantification of residual solvent
in drug formations using mesoporous silica loaded with ibuprofen dissolved
in DCM and MeOH as test samples. Interestingly, formulations prepared
using as-received or predried mesoporous silica contained 5465 versus
484.9 ppm DCM, respectively. This implies that the initial water content
of the silica carrier can impact the residual solvent concentration
in drug-loaded materials. This observation could provide new options
to minimize the occurrence of these undesired solvents in the final
formulation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.