Search

Softgel encapsulation is an important manufacturing process used to produce convenient oral dosage forms of pharmaceuticals and dietary supplements. An important step in this process involves the injection of a fill material into a gelatin lined mold, and poor flow of the fill material during the injection may lead to undesired defects. We investigated the effect of fill composition on the injection behavior of an oil-based tricalcium phosphate (TCP) suspension containing lecithin by rheological measurements, capillary breakup extensional rheometry (CaBER), and high-speed flow visualization experiments. Shear rheology for TCP suspensions in soybean oil at concentrations of 27.8 wt% and 55.6 wt% showed shear thinning behaviors both with and without the addition of lecithin. Adding up to 0.5 wt% lecithin led to decreases in shear viscosity, while additions up to 1 wt% caused a slight increase. Results from CaBER and breakoff studies indicated that the length at which flow breakoff occurs was closely related to the Ohnesorge number, a dimensionless parameter representing the relative importance of viscous to surface-tension forces during breakoff, with higher values correlated to longer breakoff lengths. An optimal lecithin concentration exists for minimized TCP suspension viscosity which shortens flow breakoff times and improves softgel capsule seaming quality., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Silicon gravure patterns are engineered to have cells that are wettable and lands that are not wettable by aqueous inks. This strategy allows excess ink on the lands to be removed without using a doctor blade. Using an aqueous silica ink, continuous lines as narrow as 1.2 μm with 1.5 μm space are gravure printed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new controlled environment vitrification system (CEVS) has been designed and constructed to facilitate examination by cryogenic scanning electron microscopy (Cryo-SEM) of initial suspension state and of microstructure development in latex, latex-composite and other coatings while they still contain solvent. The new system has a main chamber with provisions for coating as well as drying, and for well-controlled plunging into cryogen. An added subsidiary chamber holds samples for drying or annealing over minutes to days before they are returned to the main chamber and plunged from it. In the main chamber, samples are blade-coated on 5 x 7 mm pieces of silicon wafer and held at selected temperature and humidity for successively longer times, either there or after transfer along a rail into the subsidiary chamber. They are then placed in the sample holder mounted on the plunge rod, so as to permit adjustment of the sample's attitude when it plunges, at controlled speed, into liquid ethane at its freezing point, to a chosen depth, in order to solidify the sample without significant shear or freezing artifacts. The entries of plunging samples and related sample holders into liquid ethane were recorded with a high-speed, high-resolution Photron digital camera. The data were interpreted with a new hypothesis about the width of the band of extremely rapid cooling by deeply subcooled nucleate boiling below the line of entry. Complementary cryo-SEM images revealed that the freezing rate and surface shearing of a sample need to be balanced by adjusting the plunging attitude.