Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators using artificial sun lamps.

AIMS: Assess the feasibility of using light from artificial sun lamps to decontaminate N95 filtering facepiece respirators (FFRs) contaminated with SARS-CoV-2. METHODS AND RESULTS: FFR coupons or whole FFRs contaminated with 5 log10 TCID50 (target concentration) SARS-CoV-2 in culture media, simulated saliva, or simulated lung fluid were dried for 1-2 h, then exposed to light from tanning and horticulture lamps to assess decontamination. Exposed coupons and whole FFRs showed SARS-CoV-2 inactivation for all matrices tested. Furthermore, FFRs still met performance specifications after five decontamination cycles. CONCLUSIONS: It is feasible that artificial sunlight from these sun lamps can be used to decontaminate FFRs provided the UV dose is sufficient and the light is unobstructed. Furthermore, decontamination can be performed up to five times without degrading FFR performance. SIGNIFICANCE AND IMPACT OF THE STUDY: This research shows a proof of principle that artificial sun lamps may be an option to decontaminate SARS-CoV-2 on N95 FFRs. UV doses required for inactivation to levels below detection ranged from 4 to 37·8 J cm-2 depending on the light source, virus matrix and FFR type.

Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators (FFRs) with moist heat generated by a multicooker.

Decontamination of N95 filtering facepiece respirators (FFRs) is a crisis capacity strategy allowed when there are known shortages of FFRs. The application of moist heat is one decontamination method that has shown promise and is the approach approved in the Steris Steam Emergency Use Authorization (EUA). This effort examines the use of multicookers to apply moist heat, as they are available in retail stores and more affordable than methods requiring more sophisticated equipment. Four of five multicooker models examined met the acceptance criteria for the test and one model was selected for inactivation testing. Tests were performed on four different FFR models with SARS-CoV-2 suspended in culture media, simulated saliva or simulated lung fluid. Moist heat treatment reduced recoverable titres of SARS-CoV-2 virus to levels below the limit of detection in all tests. Furthermore, these four FFR models showed no loss in collection efficiency, inhalation resistance or visual damage after up to 10 decontamination cycles. Two (2) FFR models showed a slight change in strap elasticity (<9%). These data show that moist heat treatment using a multicooker is a viable option for FFR decontamination in a crisis capacity strategy.

Fluctuations of the tensor order-parameter modes in a cholesteric liquid crystal.

We use a Landau-de Gennes free energy to calculate the fluctuations of the five independent modes of the tensor order parameter for a cholesteric liquid crystal. Our results include, as a limiting case, the two classical director modes, known as the twist mode and the "umbrella" mode. We find, however, in contrast to the classical director model, that there can be substantial temperature dependence to the umbrella mode, as well as three additional modes near the transition to the isotropic phase. We comment on a recent experiment that suggests that two of these additional modes may have already been detected.

Proposal for the temperature-electric-field phase diagram of a ferroelectric smectic-C* liquid crystal.

We report on the results of extensive optical measurements on the ferroelectric smectic-C* phase of the chiral liquid crystal 4-(2(') methyl butyl) phenyl 4(')-n-octylbiphenyl-4-carboxylate. We have explored the entire temperature-electric-field phase space searching for all possible phase transitions in the C* region and have characterized them both as to their character, including whether they are first or second order, and also whether they are of instability or nucleation type. Our results lead us to conclude that the experimental phase diagram is incompatible with all existing theoretical models for the C* phase transitions. We propose instead a phase diagram where two second-order lines and one first-order line meet at a triple point that we tentatively identify as a Lifshitz point.

Orthodontic therapy in patients with juvenile periodontitis: clinical and microbiologic effects.

The correction of malocclusions in juvenile periodontitis (JP) patients completing periodontal therapy is a problem of increasing clinical concern to orthodontists, since many teeth with severe alveolar bone loss in these patients can now be successfully treated without extraction. In this report, fixed edgewise orthodontic therapy was carried out after the completion of periodontal therapy on four JP patients. The orthodontic therapy included extensive intrusion of teeth severely affected by JP. Phase-contrast microscopic analysis of subgingival plaque from orthodontically treated teeth was used to monitor longitudinally the effects of fixed orthodontic bands on the subgingival flora and also to monitor the efficacy of topical and systemic antimicrobial therapy aimed at suppression of suspected periodontopathic bacteria. Orthodontic movement was completed on most periodontally compromised teeth without significant evidence of additional deterioration in periodontal status. However, within the first 6 months of orthodontic band placement, all patients had significant increases in the number of spirochetes and motile rods in their subgingival flora. Three of the patients also developed high levels of crevicular polymorphonuclear leukocytes around orthodontically treated teeth, indicating significant subgingival inflammation. Intensive antimicrobial measures, including topical inorganic salt applications and systemic tetracycline, were helpful in limiting clinical inflammation and subgingival colonization by periodontopathogens during orthodontic therapy. The results demonstrate that successful orthodontic repositioning can be carried out in treated JP patients. In addition, bacteriologic monitoring and chemotherapeutic suppression of periodontal pathogens may be valuable in the prevention of further destructive periodontal disease activity in periodontitis patients undergoing orthodontic therapy.