Influence of Gas Temperature on Gaseous Products Generated by Coplanar Barrier Discharge in Air and N2/O2 Mixtures

Absolute densities of gaseous products generated by coplanar dielectric barrier discharge in N2/O2 mixtures and in ambient air were determined by UV optical absorption spectroscopy (OAS). Ozone (O3) and nitrogen oxides (N2O, NO2 and N2O5) were identified as the stable products of the discharge. It was found that the actual product composition strongly depends on the gas temperature. At low input power with the low gas temperature, O3 density was high and the NO2 density was very low. When the input power increased and the gas temperature also increased, then O3 disappeared, while NO2 density started to increase steeply

Modelling of inactivation kinetics of Escherichia coli, Salmonella Enteritidis and Bacillus subtilis treated with a multi-hollow surface dielectric barrier discharge plasma

Abstract The efficacy of multi-hollow surface dielectric barrier discharge treatment against Escherichia coli, Salmonella Enteritidis and Bacillus subtilis was studied. Ambient air, O2, and N2 were used as working gas with a flow rate of 6 l/m. Power delivered into plasma was 30 W over an area of 2 × 2 cm2. The active species in plasma generated in different gases participating in the inactivation of microorganisms were evaluated by optical emission spectroscopy and Fourier transform infrared spectroscopy. Inactivation curves were fitted to the Bigelow log-linear, the biphasic, and Geeraerd models. According to the results, all plasma treatments inactivated tested microorganisms, depending on a working gas. The most sensitivity of bacteria was observed to the ambient air plasma. Inactivation up to 5 log for E. coli and S. Enteritidis could be achieved within 15 s of plasma treatment. Air plasma exposure of 25 s also led to log10 CFU/ml of B. subtilis from 7.98 to 4.39. S. Enteritidis was slight resistance to plasma treatment with N2. Within 180 s nitrogen plasma treatment, a 2.04 log10 CFU/ml reduction was recorded

ABA and BAB Triblock Copolymers Based on 2-Methyl-2-oxazoline and 2-n-Propyl-2-oxazoline: Synthesis and Thermoresponsive Behavior in Water

Inspired by the well-known amphiphilic block copolymer platform known as Pluronics or poloxamers, a small library of ABA and BAB triblock copolymers comprising hydrophilic 2-methyl-2-oxazoline (A) and thermoresponsive 2-n-propyl-2-oxazoline (B) is synthesized. These novel copolymers exhibit temperature-induced self-assembly in aqueous solution. The formation and size of aggregates depend on the polymer structure, temperature, and concentration. The BAB copolymers tend to agglomerate in water, with the cloud point temperature depending on the length of poly(2-n-propyl-2-oxazoline) chain. On the other hand, ABA copolymers form smaller aggregates with hydrodynamic radius from 25 to 150 nm. The dependence of viscosity and viscoelastic properties on the temperature is also studied. While several Pluronic block copolymers are known to form thermoreversible hydrogels in the concentration range 20–30 wt%, thermogelation is not observed for any of the investigated poly(2-oxazoline)s at the investigated temperature range from 10 to 50 °C. (Figure presented.). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimINST 93/774-1 FUGG, DFG, Deutsche Forschungsgemeinschaft; LO1504, MŠMT, Ministerstvo Školství, Mládeže a TělovýchovyMinistry of Education, Youth, and Sports of Czech Republic - Program NPU I [LO1504]; Slovak Grant Agency VEGA [2/0163/15]; Deutsche Forschungsgemeinschaft [INST 93/774-1 FUGG]; State of Bavaria; University Wurzburg; SKZ Das Kunststoff-Zentru

Atmospheric pressure plasma assisted calcination of composite submicron fibers

The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination

Inactivation of Escherichia coli on PTFE surfaces by diffuse coplanar surface barrier discharge

The non-equilibrium plasma of diffuse coplanar surface barrier discharge (DCSBD) was tested for decontamination of bacteria Escherichia coli on polymer surfaces. We investigated the optical parameters of DCSBD plasma generated in synthetic air with different relative humidity. Our study was provided to estimate the main plasma components active during the DCSBD plasma degradation of E. coli contamination prepared on polytetrafluoroethylene (PTFE, Teflon) surface, in ambient air at atmospheric pressure. The DCSBD plasma was characterized by means of electrical measurements and optical emission spectroscopy. The inactivation of E. coli bacteria was evaluated by standard microbiological cultivation (CFU plate counting). The experimental results of the germicidal efficiency obtained for short plasma exposure times proved the effectiveness of DCSBD plasma for the polymer surface decontamination

Hybrid Hydrogel Networks by Photocrosslinking of Thermoresponsive alpha,omega-Itaconyl-PLGA-PEG-PLGA Micelles in Water: Influence of the Lithium Phenyl-2,4,6-Trimethylbenzoylphosphinate Photoinitinator

Modification of thermogelling biodegradable copolymers with functional groups enables further covalent crosslinking of physical micelle-based hydrogels formed at specific temperature in water. The resulting hybrid hydrogel network exhibits an increase in stiffness and degradation stability. In this work, synthesized well-defined thermoresponsive alpha,omega-itaconyl-poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (alpha,omega-itaconyl-PLGA-PEG-PLGA) macromonomers with a high degree of itaconyl-substitution providing free double bonds are photocrosslinked in water at both 25 and 37 degrees C using lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LiTPO) acting as water-soluble non-toxic photoinitiator. The effect of LiTPO on the thixotropic behavior of macromonomer in water at 25 degrees C without irradiation is evaluated. With the addition of a low amount of the photoinitiator (0.1 wt%), the degree of copolymer thixotropy increases. However, further increase in the photoinitiator concentration (0.5-3 wt%) leads to a lower degree of thixotropy. The photoinitiator is presumably interfering with the micellar self-assembly of the copolymer. This trend is also reflected in photocrosslinking efficiency, where the hybrid hydrogel networks with the highest storage moduli are achieved with very low concentrations of the photoinitiator (0.1 wt%) at 25 degrees C, while this trend is reversed at 37 degrees C. The hydrolytic stability of hydrogels prepared at 37 degrees C from 17 wt% macromonomer solution with 1% LiTPO exceeds 22 days.Modifikace termosenzitivních biodegradabilních kopolymerů s funkčními skupinami umožňuje další kovalentní zesíťování fyzikálních hydrogelů na bázi micel vytvořených ve vodě při specifické teplotě. Výsledná hybridní hydrogelová síť vykazuje zvýšení tuhosti a degradační stability. V této práci byly syntetizováné dobře definované termoresponzivní , itaconylPLGAPEGPLGA) makromonomery s vysokým stupněm substituce kyseliny itakonové s volnými dvojnými vazbami, které byly fotosíťovány ve vodě při 25 i 37 ° C v přítonosti ve vodě rozpustného netoxického fotoiniciátoru lithium-fenyl 2,4,6-trimethylbenzoylfosfinátu (LiTPO)

[Acrylic acid plasma treatment of polypropylene nonwoven fabric] [Włókniny polipropylenowe poddane obróbce plazmowej z zastosowaniem kwasu akrylowego]

Nowadays hydrogel materials are being used in medical practice for wound dressing purposes. Hydrogel/textile composites can be formed to increase the mechanical strength and handling capability of hydrogel materials. Nonwoven textiles are optional for such applications, however, it is often necessary to improve their surface properties. Here plasma activation/grafting of polypropylene (PP) nonwoven fabric with an acrylate layer to improve its adhesive properties is reported. A diaphragm discharge was used for the plasma treatment of the PP fabric. The discharge was burnt in a solution of acrylic acid (AAc), which resulted in a single step process of plasma activation and plasma grafting of the fabric. Results of wettability testing and ATR-FTIR measurements showed the existence of a thin poly(acrylic acid) (PAAc) layer grafted on the fabric surface. Peel strength measurements showed a 4.7 fold increase in the peel strength when compared with untreated PP fabric.This publication is the result of the project: "Applied research and development of innovative drilling technology for ultra--deep geothermal wells", ITMS code 26240220042, supported by the Rese-arch & Development Operational Pro-gramme funded by the ERDF. This work was supported by the Slovak Research and Development Agency under contract No. APVV-14-0518.Scopu

Poly(2-oxazoline)-based magnetic hydrogels: Synthesis, performance and cytotoxicity

Research on the subject of smart biomaterials has become a cornerstone of tissue engineering and regenerative medicine. Herein, the authors report on developing magnetic hydrogels that combine high biocompatibility and remarkable activity in magnetic fields. We fabricated magnetic hydrogels based on poly(2-ethyl-2-oxazoline) (POx) via living ring-opening cationic polymerization with in-situ embedding of the carbonyl iron (CI) particles. Investigation was made as to the effect exerted by the concentration of CI on magnetic, viscoelastic/magnetorheological properties, the degree of equilibrium swelling, and cytotoxicity. The hydrogels exhibited an open pore structure, as evidenced by computed tomography (CT) imaging. Susceptibility measurements revealed the concentration-dependent field-induced particle restructuration indicating elongation/contraction of the material, thereby determining the potential for magneto-mechanical stimulation of the cells. The POx-based magnetic hydrogels were amphiphilic in character, showing decrease in their capability to hold liquid alongside increase in CI concentration. Viscoelastic measurements suggested that interaction occurred between the particles and matrix based on inconsistency between the experimental storage modulus and the Krieger–Dougherty model. The synthesized materials exhibited excellent biocompatibility toward the 3T3 fibroblast cell line in tests of extract toxicity and direct contact cytotoxicity (ISO standards). The unique combination of properties exhibited by the material - magneto-mechanical activity and biocompatibility - could prove favorable in fields such as biomedicine and biomechanics. © 2020 Elsevier B.V.Czech Science FoundationGrant Agency of the Czech Republic [17-24730S]; Slovak Grant Agency VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0124/18]; EU Funds - OP Research, Development and Education [CZ.02.2.69/0.0/0.0/16_027/0008464]; Ministry of Education, Youth and Sports, Czech RepublicMinistry of Education, Youth & Sports - Czech RepublicCzech Republic Government; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504

In vitro study of partially hydrolyzed poly(2-ethyl-2-oxazolines) as materials for biomedical applications

Polymers based on 2-oxazoline, such as poly(2-ethyl-2-oxazolines) (PETOx), are considered to be a type of 'pseudopeptide' with the ability to form novel biomaterials. The hydrolysis of PETOx was carried out to evaluate its use in biomedical applications. In the present work, PETOx samples with a range of molar masses were prepared by living cationic polymerization. Hydrolysis was carried out at time intervals ranging from 15 to 180 min to prepare copolymers with different amounts of ethylene imine units. H-1 NMR spectroscopy was used to identify the structure of the hydrolyzed polymers. The dependence of in vitro cell viability on the degree of hydrolysis was determined using three different model cell lines, namely, mouse embryonic 3T3 fibroblasts, pancreatic beta TC3 cells, and mouse lymphoid macrophages P388.D1. It was demonstrated that increasing the degree of hydrolysis decreased cell viability for all cell types. Fibroblast cells displayed the highest tolerance; additionally, the effect of polymer size showed no observable significance. Macrophage cells, immune system representatives, displayed the highest sensitivity to contact with hydrolyzed PETOx. The effect of polymer hydrolysis, polymer concentration and the incubation time on cell viability was experimentally observed. Confocal laser-scanning microscopy provided evidence of cellular uptake of pyrene-labeled (co)polymers.Slovak Grant Agency, VEGA [2/0151/12, 2/0163/12]; Operational Program Education for Competitiveness; European Social Fund (ESF); national budget of the Czech Republic [CZ.1.07/2.3.00/20.0104]; Ministry of Education, Youth and Sports of the Czech Republic [ME-LH14050

Carbonyl iron coated with a sulfobetaine moiety as a biocompatible system and the magnetorheological performance of its silicone oil suspensions

In this study, surface modification of carbonyl iron (CI) particles with sulfobetaine moieties (SBE) was performed by the silanization of activated CI to form stable CI-SBE particles. The modification led to a significant improvement of the thermo-oxidation stability and a negligible suppression of the magnetization of the particles, as revealed by thermogravimetric analysis and vibrating sample magnetometry, respectively. The effect of a magnetic field and temperature on the magnetorheological performance of particle suspensions was investigated using a rotational rheometer in order to clarify the suitability of these systems for the local embolization of blood veins. The suspension based on CI-SBE exhibited a pseudoplastic behaviour and a tunable yield stress in a range from 0.3-4 kPa at the normal human body temperature. Moreover, cell viability for fibroblasts and macrophages was examined via MTT assay, which revealed their suitability for the intended applications for the local embolization of blood veins. © The Royal Society of Chemistry 2016.NPRP from the Qatar National Research Fund (a member of Qatar Foundation) [NPRP-6-381-1-078]; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]; Internal Grant Agency of the Czech Republic [IGA/CPS/2016/008]; Slovak Grant Agency, VEGA [2/0156/15