Techniques for the generation and monitoring of vapors

Controlled test atmospheres can be produced using a variety of techniques. Gases are usually generated by using flow dilution methods while vapors are produced by using solvent injection and vaporization, saturation, permeation and diffusion techniques. The resulting gas mixtures can be monitored and measured using flame ionization, photoionization, electrochemical and infrared analytical systems. An ideal system for the production of controlled test atmospheres would not only be able to generate controlled test atmospheres, but also monitor all pertinent environmental parameters, such as temperature, humidity, and air flow

An acidic model pro-peptide affects the secondary structure, membrane interactions and antimicrobial activity of a crotalicidin fragment

In order to study how acidic pro-peptides inhibit the antimicrobial activity of antimicrobial peptides, we introduce a simple model system, consisting of a 19 amino-acid long antimicrobial peptide, and an N-terminally attached, 10 amino-acid long acidic model pro-peptide. The antimicrobial peptide is a fragment of the crotalicidin peptide, a member of the cathelidin family, from rattlesnake venom. The model pro-peptide is a deca (glutamic acid). Attachment of the model pro-peptide only leads to a moderately large reduction in the binding to- and induced leakage of model liposomes, while the antimicrobial activity of the crotalicidin fragment is completely inhibited by attaching the model pro-peptide. Attaching the pro-peptide induces a conformational change to a more helical conformation, while there are no signs of intra- or intermolecular peptide complexation. We conclude that inhibition of antimicrobial activity by the model pro-peptide might be related to a conformational change induced by the pro-peptide domain, and that additional effects beyond induced changes in membrane activity must also be involved.</p

Detecting chronic apical periodontitis for improved endodontic success

Endodontic treatments are frequently carried out in daily clinical practice. The presence or absence of a periapical radiolucency, assessed using intraoral radiographs, is one of the criteria used to determine endodontic success. When such a lesion is present around the apex of a tooth, the condition is known as chronic apical periodontitis. While this is common around root treated teeth, it can also be associated with otherwise healthy teeth. In both instances, it represents an inflammatory response to bacteria or irritants in the periapical space, and results in bone loss and areas of reduced density, which can then form apical granulomas or cysts. The literature has shown that periapical lesions can go undetected, due to the two-dimensional limitations of periapical radiographs. These “hidden” lesions can compromise the longevity of the tooth. Considering that apical periodontitis can be far more accurately detected and diagnosed on cone beam computed tomography, it has been recommended by several authors that endodontic treatment outcomes ideally should be evaluated using this imaging modality, whenever possible.https://www.sada.co.za/the-sadjam2018Prosthodontic