Antimicrobial Effects of Microwave-Induced Plasma Torch (MiniMIP) Treatment on Candida Albicans Biofilms

The susceptibility of Candida albicans biofilms to a non-thermal plasma treatment has been investigated in terms of growth, survival and cell viability by a series of in vitro experiments. For different time periods , the C. albicans strain SC5314 was treated with a microwave-induced plasma torch (MiniMIP). The MiniMIP treatment had a strong effect (reduction factor (RF) = 2.97 after 50 s treatment) at a distance of 3 cm between the nozzle and the superior regions of the biofilms. In addition, a viability reduction of 77% after a 20 s plasma treatment and a metabolism reduction of 90% after a 40 s plasma treatment time were observed for C. albicans. After such a treatment , the biofilms revealed an altered morphology of their cells by atomic force microscopy (AFM). Additionally , fluorescence microscopy and confocal laser scanning microscopy (CLSM) analyses of plasma-treated biofilms showed that an inactivation of cells mainly appeared on the bottom side of the biofilms. Thus, the plasma inactivation of the overgrown surface reveals a new possibility to combat biofilms

Antimicrobial effects of microwave-induced plasma torch (MiniMIP) treatment on Candida albicans biofilms

The susceptibility of Candida albicans biofilms to a non-thermal plasma treatment has been investigated in terms of growth, survival and cell viability by a series of in vitro experiments. For different time periods, the C. albicans strain SC5314 was treated with a microwave-induced plasma torch (MiniMIP). The MiniMIP treatment had a strong effect (reduction factor (RF) = 2.97 after 50 s treatment) at a distance of 3 cm between the nozzle and the superior regions of the biofilms. In addition, a viability reduction of 77% after a 20 s plasma treatment and a metabolism reduction of 90% after a 40 s plasma treatment time were observed for C. albicans. After such a treatment, the biofilms revealed an altered morphology of their cells by atomic force microscopy (AFM). Additionally, fluorescence microscopy and confocal laser scanning microscopy (CLSM) analyses of plasma-treated biofilms showed that an inactivation of cells mainly appeared on the bottom side of the biofilms. Thus, the plasma inactivation of the overgrown surface reveals a new possibility to combat biofilms. © 2019 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology

On the plasma chemistry of a cold atmospheric argon plasma jet with shielding gas device

ABSTRACT: A novel approach combining experimental and numerical methods for the study of reaction mechanisms in a cold atmospheric Ar plasma jet is introduced. The jet is operated with a shielding gas device that produces a gas curtain of defined composition around the plasma plume. The shielding gas composition is varied from pure N₂ to pure O₂. The density of metastable argon Ar(4s,³P₂) in the plasma plume was quantified using laser atom absorption spectroscopy. The density of long-living reactive oxygen and nitrogen species (RONS), namely O₃, NO₂, NO, N₂O, N₂O₅ and H₂O₂, was quantified in the downstream region of the jet in a multipass cell using Fourier-transform infrared spectroscopy (FTIR). The jet produces a turbulent flow field and features guided streamers propagating at several km s⁻¹ that follow the chaotic argon flow pattern, yielding a plasma plume with steep spatial gradients and a time dependence on the ns scale while the downstream chemistry unfolds within several seconds. The fast and highly localized electron impact reactions in the guided streamer head and the slower gas phase reactions of neutrals occurring in the plasma plume and experimental apparatus are therefore represented in two separate kinetic models. The first electron impact reaction kinetics model is correlated to the LAAS measurements and shows that in the guided streamer head primary reactive oxygen and nitrogen species are dominantly generated from Ar(4s,³P₂). The second neutral species plug-flow model hence uses an Ar(4s,³P₂) source term as sole energy input and yields good agreement with the RONS measured by FTIR spectroscopy

Untersuchungen zur Frequenzdurchstimmung eines Diodenlasers mit externem Resonator basierend auf dem akusto-optischen Effekt

In der Frequenz kontinuierlich veränderbare Laser sind interessante Lichtquellen für wissenschaftliche Forschung, Industrie und Technik. In diesem Zusammenhang zeigen insbesondere Diodenlaser mit externem Resonator (ECDL) vorteilhafte Eigenschaften. Weit verbreitet ist der Littrow-Laser, da er aufgrund seines einfachen Designs kostengünstig, kompakt und robust ist und zudem eine geringe Linienbreite aufweist. Das bei ihm eingesetzte Reflexions-Gitter fungiert gleichzeitig als Reflektor und Frequenzfilter. Die Durchstimmung erfolgt mechanisch durch Drehung des Gitters mittels eines Piezo-Aktuators. Diese Vorgehensweise begrenzt sowohl die erreichbare Repetitionsrate als auch Durchstimmbereich und -geschwindigkeit. Um diese Probleme zu umgehen, bietet sich der Einsatz zweier akusto-optischer Modulatoren (AOM) als Deflektor im externen Resonator an. Die Durchstimmung eines solchen AOM-Lasers erfolgt durch Ablenkung des Strahls auf rein nicht-mechanischem Weg. Dazu ist allerdings eine geeignete Ansteuerung der AOMs vonnöten. Im Rahmen dieser Arbeit wurde ein theoretisches Modell entworfen, welches grundlegende Eigenschaften eines AOM-Lasers beschreibt. Darauf basierend konnte ein Algorithmus zur Berechnung der für eine kontinuierliche Durchstimmung notwendigen AOM-Ansteuersignale entwickelt werden. Dieses Modell zeigt zudem, dass zur Realisierung einer Durchstimmung mit gleichzeitig akzeptabler Laser-Linienbreite hohe Anforderungen an die Ansteuerelektronik, insbesondere bezüglich Jitterfreiheit (< 5 ps), gestellt werden, was nur durch eine vollständig digitale Erzeugung der Ansteuersignale mittels sogenannter DDS-ICs (Direct-Digital-Synthesis) erfüllt werden kann. Andere untersuchte Schaltungen zeigten schlechtere Eigenschaften. Aufgrund der guten Übereinstimmung zwischen dem aufgestellten Modell und dem praktischen AOM-Laseraufbau können im roten Spektralbereich kontinuierliche (modensprungfreie) Durchstimmbereiche von bis zu 220 GHz erreicht werden. Die maximale Durchstimmgeschwindigkeit liegt 1.5 GHz/µs. Eine Repetitionsrate von 25 kHz ist realisierbar. Die 0.2-ms-Linienbreite liegt bei 450 kHz. Der Laser konnte außerdem in einem Bereich von 6 nm (4 THz) ohne mechanische Nachjustage operieren. Eine genaue Analyse zeigt, dass trotz der schon sehr guten Performance des Lasersystems durch Verfeinerung des Modells und eine weitere Verbesserung der Komponenten die genannten Leistungsparameter um einen Faktor 5 - 10 gesteigert werden könnten.Continuously tunable lasers are interesting light sources for scientific research, industry and engineering. Especially external cavity diode lasers (ECDL) have convenient properties. A popular system is the Littrow-Laser because of its small line width and its simple, compact and robust design. The there used reflection grating acts as a reflective element as well as a frequency filter. Rotating the grating by a piezo actuator results in a frequency tuning. However, this method limits the repetition rate as well as the tuning range and the tuning speed. In order to avoid these problems one can use two acousto-optical modulators (AOM) as light deflecting elements inside the external cavity. By bending the beam one can apply a frequency tuning without moving any part mechanically. However, this requires a suitable controlling of the AOMs. Therefore a theoretical model was created, describing fundamental properties of an AOM-laser. Therewith, an algorithm was developed that allows calculating the AOM driving signals for a continuously tuning of the laser. Furthermore, the model indicates that a practical realization of a tuning and a small line width are only achievable by using a very specific driving electronics. Especially the temporal jitter must be very small (< 5 ps). This was reached by a fully digital signal generation using DDS-chips (Direct-Digital-Synthesis). Other electronics yields poorer properties. Because of a good conformance between the theoretical model and the experimental AOM-laser set-up in red spectral region one can achieve continuously (mode-hop free) frequency tuning with a range up to 220 GHz and a tuning speed up to 1.5 GHz/µs. A repetition rate of 25 kHz is possible and the (0.2 ms) line width is 450 kHz. Furthermore, the laser could operate within a range of 6 nm (4 THz) without mechanically readjusting. A careful analysis indicates that the very good performance of the AOM-laser system could be enhanced by a factor 5-10 if the theoretical model and some optical elements are improved

Antimicrobial effects of microwave‐induced plasma torch (MiniMIP) treatment on Candida albicans biofilms

Summary The susceptibility of Candida albicans biofilms to a non‐thermal plasma treatment has been investigated in terms of growth, survival and cell viability by a series of in vitro experiments. For different time periods, the C. albicans strain SC5314 was treated with a microwave‐induced plasma torch (MiniMIP). The MiniMIP treatment had a strong effect (reduction factor (RF) = 2.97 after 50 s treatment) at a distance of 3 cm between the nozzle and the superior regions of the biofilms. In addition, a viability reduction of 77% after a 20 s plasma treatment and a metabolism reduction of 90% after a 40 s plasma treatment time were observed for C. albicans. After such a treatment, the biofilms revealed an altered morphology of their cells by atomic force microscopy (AFM). Additionally, fluorescence microscopy and confocal laser scanning microscopy (CLSM) analyses of plasma‐treated biofilms showed that an inactivation of cells mainly appeared on the bottom side of the biofilms. Thus, the plasma inactivation of the overgrown surface reveals a new possibility to combat biofilms

Fundamental Aspects of Filamentary Jet Discharges Interacting with Biologically Relevant Liquids and with Cells

OralInternational audienc

Management and prognostic markers in patients with autoimmune encephalitis requiring ICU treatment

Objective To assess intensive care unit (ICU) complications, their management, and prognostic factors associated with outcomes in a cohort of patients with autoimmune encephalitis (AE). Methods This study was an observational multicenter registry of consecutively included patients diagnosed with AE requiring Neuro-ICU treatment between 2004 and 2016 from 18 tertiary hospitals. Logistic regression models explored the influence of complications, their management, and diagnostic findings on the dichotomized (0-3 vs 4-6) modified Rankin Scale score at hospital discharge. Results Of 120 patients with AE (median age 43 years [interquartile range 24-62]; 70 females), 101 developed disorders of consciousness, 54 autonomic disturbances, 42 status epilepticus, and 39 severe sepsis. Sixty-eight patients were mechanically ventilated, 85 patients had detectable neuronal autoantibodies, and 35 patients were seronegative. Worse neurologic outcome at hospital discharge was associated with necessity of mechanical ventilation (sex- and age-adjusted OR 6.28; 95% CI, 2.71-15.61) tracheostomy (adjusted OR 6.26; 95% CI, 2.68-15.73), tumor (adjusted OR 3.73; 95% CI, 1.35-11.57), sepsis (adjusted OR 4.54; 95% CI, 1.99-10.43), or autonomic dysfunction (adjusted OR 2.91; 95% CI, 1.24-7.3). No significant association was observed with autoantibody type, inflammatory changes in CSF, or pathologic MRI. Conclusion In patients with AE, mechanical ventilation, sepsis, and autonomic dysregulation appear to indicate longer or incomplete convalescence. Classic ICU complications better serve as prognostic markers than the individual subtype of AE. Increased awareness and effective management of these AE-related complications are warranted, and further prospective studies are needed to confirm our findings and to develop specific strategies for outcome improvement