Dispersion of discrete sample signals within aerosol spray chambers: preliminary investigations

A barrel-type spray chamber with a baffle system and various other structures were used for characterization of band-broadening phenomena occurring within aerosol spray chambers, with an ICP-AES detector used in this case. Absolute values of aerosol particle size distributions from nebulizer/spray chamber systems were measured and found to be affected by the relative positions of impact surfaces with respect to the nebulizer. Smaller particles, but less total mass was observed as the baffle was moved closer to the nebulizer tip. However, based on measurements herein, it does not appear that particle sizes in any case will be small enough within the spray chamber for diffusion to influence band broadening for the bulk of the aerosol mass, as particularly important for mass sensitive detectors such as ICP-AES, although diffusion is likely to be important to particle number sensitive detectors.

Dispersion within the turbulent gas-phase regions of spray chambers appears to be relatively small. Geometries which introduce stagnant gas flow regions appear to have larger effects on band-broadening. The smoke tests utilized in these studies were found to be useful aids for visualization of spray chamber flow phenomena that influence dispersion of discrete signals.

Recirculation phenomena can also play a role in band broadening. Recirculation of aerosol re-entrained into the nebulizer jet appears to have an effect on dispersion, as represented by the full width at half maximum values. On the other hand, recirculation renebulization leads to substantial peak tailing.     

Synthesis and evaluation of new phosphonated δ-lactam and glutarimide derivatives as angiotensin converting enzyme inhibitors

An efficient synthesis of new γ,δ-insaturated δ-lactam and glutarimide derivatives bearing a phosphonomethyl group from a common allylphosphonate precursor is described. Our approach is based on a two-step procedure involving the preparation of phosphonated-1,5-ketoester and −1,5-diester followed by an amidation–heterocyclization sequence. The first step proceeds via Michael's addition of ethyl acetoacetate and diethyl malonate on an allylphosphonate starting material. The second step consists of a base-promoted intramolecular amidation-cyclization sequence with primary amines, which accounts for the construction of δ-lactams and glutarimide skeletons. We performed the evaluation of angiotensin I-converting enzyme (ACE) inhibition using an in vitro enzyme assay on six new compounds. Five compounds showed potent ACE inhibitory activity, with IC₅₀ values ranging from 0.02 to 0.27 mg/ml. Compared with Captopril, used as a reference drug, two new glutarimide derivatives exhibited higher efficiency ACE inhibition activity.     

A Mucin-Based Bio-Ink for 3D Printing of Objects with Anti-Biofouling Properties

With its potential to revolutionize the field of personalized medicine by producing customized medical devices and constructs for tissue engineering at low costs, 3D printing has emerged as a highly promising technology. Recent advancements have sparked increasing interest in the printing of biopolymeric hydrogels. However, owing to the limited printability of those soft materials, the lack of variability in available bio-inks remains a major challenge. In this study, a novel bio-ink is developed based on functionalized mucin—a glycoprotein that exhibits a multitude of biomedically interesting properties such as immunomodulating activity and strong anti-biofouling behavior. To achieve sufficient printability of the mucin-based ink, its rheological properties are tuned by incorporating Laponite XLG as a stabilizing agent. It is shown that cured objects generated from this novel bio-ink exhibit mechanical properties partially similar to that of soft tissue, show strong anti-biofouling properties, good biocompatibility, tunable cell adhesion, and immunomodulating behavior. The presented findings suggest that this 3D printable bio-ink has a great potential for a wide range of biomedical applications, including tissue engineering, wound healing, and soft robotics.