Effects of porosity on drug release kinetics of swellable and erodible porous pharmaceutical solid dosage forms fabricated by hot melt droplet deposition 3D printing

3D printing has the unique ability to produce porous pharmaceutical solid dosage forms on-demand. Although using porosity to alter drug release kinetics has been proposed in the literature, the effects of porosity on the swellable and erodible porous solid dosage forms have not been explored. This study used a model formulation containing hypromellose acetate succinate (HPMCAS), polyethylene oxide (PEO) and paracetamol and a newly developed hot melt droplet deposition 3D printing method, Arburg plastic free-forming (APF), to examine the porosity effects on in vitro drug release. This is the first study reporting the use of APF on 3D printing porous pharmaceutical tablets. With the unique pellet feeding mechanism of APF, it is important to explore its potential applications in pharmaceutical additive manufacturing. The pores were created by altering the infill percentages (%) of the APF printing between 20 to 100% to generate porous tablets. The printing quality of these porous tablets were examined. The APF printed formulation swelled in pH 1.2 HCl and eroded in pH 6.8 PBS. During the dissolution at pH 1.2, the swelling of the printing pathway led to the gradual decreases in the open pore area and complete closure of pores for the tablets with high infills. In pH 6.8 buffer media, the direct correlation between drug release rate and infills was observed for the tablets printed with infill at and less than 60%. The results revealed that drug release kinetics were controlled by the complex interplay of the porosity and dynamic changes of the tablets caused by swelling and erosion. It also implied the potential impact of fluid hydrodynamics on the in vitro data collection and interpretation of porous solids

Effect of Sn on the Dehydrogenation Process of TiH2 in Al Foams

The study of the dehydrogenation process of TiH2 in aluminum foams produced by the powder metallurgy technique is essential to understanding its foaming behavior. Tin was added to the Al foam to modify the dehydrogenation process and stabilize the foam. A gradual decomposition and more retention of hydrogen gas can be achieved with Sn addition resulting in a gradual and larger expansion of the foam

Interplay of Linker Functionalization and Hydrogen Adsorption in the Metal–Organic Framework MIL-101

Functionalization of metal–organic frameworks results in higher hydrogen uptakes owing to stronger hydrogen–host interactions. However, it has not been studied whether a given functional group acts on existing adsorption sites (linker or metal) or introduces new ones. In this work, the effect of two types of functional groups on MIL-101 (Cr) is analyzed. Thermal-desorption spectroscopy reveals that the −Br ligand increases the secondary building unit’s hydrogen affinity, while the −NH2 functional group introduces new hydrogen adsorption sites. In addition, a subsequent introduction of −Br and −NH2 ligands on the linker results in the highest hydrogen-store interaction energy on the cationic nodes. The latter is attributed to a push-and-pull effect of the linkers

Thermal desorption spectroscopy as a quantitative tool to determine the hydrogen content in solids

Thermal desorption spectroscopy (TDS) utilising a quadrupolar mass spectrometer is a highly sensitive and selective method to study the hydrogen desorption of hydrogen storage materials. For a quantitative analysis of the hydrogen storage capacity, the TDS apparatus can be consistently calibrated by using hydrogenated PdGd alloys or TiH2 as standards. Owing to its hygroscopic nature, the use of CaH2 as calibration standard leads to erroneous results. The chemical reactions during the thermal desorption of CaH2 are analysed in detail

Desorption of hydrogen from blowing agents used for foaming metals

Hydrogen desorption from TiH2, ZrH2, and MgH2 was studied by thermal desorption spectroscopy TDS , differential thermal analysis DTA and thermogravimetric analysis TGA . Loose hydride powders as well as powder compacts of zinc and various hydrides were studied. It was found that during the powder compaction process free surfaces on the hydride powder particles were created. As a consequence, the desorption temperature of the hydride in the precursor was lowered in comparison to loose powder exposed to air. Foam expansion of zinc was highest for TiH2 which also exhibits the highest desorption rate at the melting point of zinc, followed by ZrH2 and MgH2 which decompose at lower temperatures and are therefore less effective for foaming. The desorption kinetics of Al and AlSi7 compacts containing TiH2 were also studied for matters of comparison. The much lower foam expansions compared to Zn foams could be explained by higher hydrogen losses at temperatures below the melting point of Al and AlSi