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Atmospheric pressure (AP) dielectric barrier discharges (DBDs) are increasingly used to treat thermally-sensitive materials. Reliable measurements of the kinetic gas temperature, T, are therefore of capital importance. Spectroscopically determined rotational temperatures, Trot, are often tacitly assumed to be equal to T. Here, we measured T with fibre-optic instrumentation that is a priori immune towards high voltages and high-frequency electromagnetic fields generally encountered in plasmas. Finding Trot > T in AP glow discharge (APGD) DBDs in He and Ne, we believe that Trot ≈ T only during the short (≈ µs) current peaks that characterize APGD. Therefore, T represents the time-averaged gas temperature; calorimetric measurements using a thermocouple buried in an electrode support this view. [ABSTRACT FROM AUTHOR]

Bone metastasis is a frequent occurrence following breast cancer. The bone‐tumor microenvironment is heterogeneous and complicated to recapitulate. The development of new chemotherapeutics is ineffective partly due to a lack of precise in vitro tissue models. We developed a three‐dimensional (3D) bone‐tumor interface model for customized chemotherapeutic screening. It comprises a plasma‐modified electrospun mat seeded with osteoblasts to mimic a bone tissue, with a cell‐seeded hydrogel layer containing more and less aggressive or noncancerous cells on top, mimicking the tumor compartment. By screening the model with doxorubicin, we observed different migratory behaviors, with IC50 values that were largely in accordance with those cell lines' characteristics. Our 3D model reproduces the bone microenvironment and has great potential as a drug screening tool for personalized medicine. [ABSTRACT FROM AUTHOR]

We report on a methodology for measuring the energy dissipated per AC high voltage cycle in a cold atmospheric pressure plasma jet (CAPJet). This method is adapted from research by Nisol et al. on plasma polymerization of hexamethyldisiloxane (HMDSO) organosilicon vapor in a large area planar dielectric barrier discharge (DBD) reactor. Here too, we measured ΔEg, the energy difference with and without small HMDSO vapor concentrations in the argon carrier gas flow. From ΔEg we then derived Em, the energy per molecule, and compared values with those of Nisol. Good agreements were found, including in film structures determined from attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectra, thus suggesting that realistic Em values can be successfully obtained also for the CAPJet case. [ABSTRACT FROM AUTHOR]

The method we have developed for understanding energetic exchanges between precursor molecules and argon (Ar) carrier gas in a dielectric barrier discharge (DBD) has much‐proven merit. The present article focuses on hydrofluoromethanes, CHxFy. The precursors (‰ concentrations) were mixed with Ar in a 20 kHz, 8 kV (peak‐to‐peak) DBD. For each compound, Em, the energy absorbed per molecule, was plotted as a function of precursor flow rate. Besides the determination of Em, we have used optical emission spectroscopy as a diagnostic of the plasma physicochemistry. The influence of chemical structure has been investigated by depositing thin plasma polymer coatings; we have measured their deposition rates and water contact angles, which have been correlated with Em values and X‐ray photoelectron spectroscopy measurements. [ABSTRACT FROM AUTHOR]

Aging (or "hydrophobic recovery") of plasma‐modified polymer surfaces has been known and documented in the literature over several decades; to the best of our knowledge, the present study appears to be the first in which this is done for two vastly different rough surface structures: (i) electrospun nanofibrous (NF) mats, and (ii) flat films (FF), for three polymers of well‐documented interest in biotechnological applications: poly(lactic acid); poly(urethane); and poly(caprolactone). Two different plasma treatments are applied: low‐pressure (LP) radio‐frequency (rf) glow discharges in flows of O2 and NH3 under mild power conditions. Measured time‐dependent surface compositions (from X‐ray photoelectron spectroscopy survey spectra) and water contact angles (WCA) were found to tend toward asymptotic limiting values after ca. 30 days of storage in clean air, as previously reported by these and other authors. An entirely novel aspect of this work is to examine and compare time‐dependent WCA behaviors of NF and FF samples in terms of Wenzel (W) and Cassie‐Baxter (C‐B) model behaviors, including possible transitions from C‐B to W and their interpretation. [ABSTRACT FROM AUTHOR]

Thiol (SH)-terminated surfaces have been progressively gaining interest over the past years as a consequence of their widespread potential applications. Here, SH-terminated thin films have been prepared by 'co-polymerizing' gas mixtures comprising ethylene (C2H4) or butadiene (C4H6) with hydrogen sulfide (H2S). This has been accomplished by either vacuum-ultraviolet (VUV) irradiation of the flowing gas mixtures with near-monochromatic radiation from a Kr lamp, or by low-pressure r.f. plasma-enhanced chemical vapor deposition (PECVD). Varying the gas mixture ratio, R, allows one to control the films' sulfur content as well as the thiol concentration [SH]. The deposits were characterized by X-ray photoelectron spectroscopy (XPS), before and after chemical derivatization with N-ethylmaleimide, and by ATR FTIR. VUV- and plasma-prepared coatings were found to possess very similar structures and characteristics, showing chemically bonded sulfur concentrations, [S], up to 48 at% and [SH] up to 3%. All coatings remained essentially unchanged in thickness after immersion in water for 24 h. [ABSTRACT FROM AUTHOR]

Thin organic films with oxygen-bearing functional groups (hydroxyl, carboxyl, ...) were prepared by 'co-polymerizing' gas mixtures of ethylene (C2H4) and one of several O-containing oxidizer molecules, O2, CO2, or N2O. This was done either by vacuum-ultraviolet (VUV) photo-polymerization or by low-pressure r.f. plasma-assisted CVD. The gas mixture ratio, R, permits one to control total oxygen concentration, [O], as well as the relative proportions of the various functionalities. Analyses were performed by XPS (with or without chemical derivatization using TFAA to determine [OH] content), and IRRAS-FTIR. Temporal and structural stability (mass change) of deposits under exposure to air or water was examined; altogether, data confirmed different reaction pathways for VUV and PECVD. [ABSTRACT FROM AUTHOR]

We present precision measurements of the energy, Eg, dissipated per period of the applied ac voltage at kHz frequencies (4 ≤ f ≤ 32 kHz) by atmospheric-pressure glow discharges (APGD) in flows of helium and neon. Such data are important for determining the efficiency of excimer light sources, for example. We report the methodology and specific steps taken to achieve the desired degrees of precision and reproducibility, and compare our results with data published in the literature. [ABSTRACT FROM AUTHOR]

A versatile pilot‐scale reactor has been designed in such a way that it can be readily converted from a dielectric barrier discharge "PECVD" operating mode into a photoinitiated "PICVD" one; in the latter, low‐pressure mercury (Hg) lamps replace the high‐voltage glow discharge plasma. Both processes operate at ambient temperature and atmospheric pressure, 100 kPa, using acetylene (C2H2) monomer. In both sets of experiments, it was found that efficient gas‐to‐solid conversion can occur in the form of a nanoparticulate amorphous hydrocarbon polymer‐like material. It was found that in the PICVD case, great care was required to exclude even traces of O2 contamination, because it not only reduced the growth rate of solid, but the latter then became highly oxidized ([O] ~50 at.%) and water‐soluble. [ABSTRACT FROM AUTHOR]

Thiol (SH)‐terminated surfaces have gained interest over the past years due to their potential applications, especially in the biomedical field. In this work, SH‐terminated films have been prepared by “co‐polymerizing” gas mixtures of acetylene (C2H2) and hydrogen sulfide (H2S) using low‐pressure r.f. plasma‐enhanced chemical vapor deposition. R.f. power greatly influences the deposition rate, sulfur content, [S], and thiol concentration, [SH], of the films, as confirmed by XPS (both before and after chemical derivatization), FTIR, and mass spectrometry measurements. These data are compared with those obtained in a similar discharge by using a single molecule precursor, propanethiol. Among other differences, it is demonstrated that [SH] is higher when using binary gas mixtures compared to the single molecule precursor. [ABSTRACT FROM AUTHOR]

We have studied “PEG‐like” plasma‐deposited coatings of poly(ethylene glycol), some of which prevent protein adsorption and cellular adhesion. This enables inhibition of possible inflammatory reactions or rejection of an implant following its insertion into living tissue. Our approach, based on electrical measurements in atmospheric pressure Ar dielectric barrier discharges, enables precise measurements of E m, the energy absorbed per monomer molecule. Here, we demonstrate the importance of E m in preparing PEG‐like coatings for biomedical applications, for example by highlighting the great importance of molecular weight of monoglyme (1G) or diglyme (2G) monomers, and by obtaining anti‐fouling layers, “PP‐2G,” only with the diglyme. We demonstrate resistance to protein adsorption and cell adhesion of PP‐2G surfaces prepared with optimized F d (and E m) values. [ABSTRACT FROM AUTHOR]

We report dielectric barrier discharge (DBD)-based atmospheric pressure (AP) plasma polymerization (PP) experiments using argon carrier gas and a wide variety of hydrocarbon molecules as the precursors ('monomers'). As in our preceding research with other reagents, unprecedented precision and reproducibility in energy measurements is again demonstrated. Measurements based on various aliphatic and aromatic hydrocarbon compounds have yielded values of Em, the energy absorbed from the plasma by each monomer molecule. Systematic differences among families of compounds enabled us to draw several important conclusions about fragmentation and polymerization in the DBD plasma environment, observations which are in fair qualitative agreement with low-pressure radio-frequency PP data by Yasuda and Hirotsu from the 1970s. [ABSTRACT FROM AUTHOR]

Surface modifications are often required to enhance cell adhesion and growth around implanted biomaterials. This study compares various functionalization processes in their ability to create high densities of oxygen- and/or nitrogen-containing functional groups, mostly on a polymeric biomaterial, polyethylene terephthalate (PET). Primary amine (NH2)-rich surfaces were prepared by low-pressure plasma-polymerization (L-PPE:N), plasma modification (functionalized PET, 'PETf'), chemical vapour deposition (Parylene diX AM), and grafting of polyallylamine (PAAm). Plasma polymerization was also used to obtain oxygen-rich (L-PPE:O) as well as hybrid (L-PPE:O,N) films, which were respectively compared to oxygen-rich tissue culture polystyrene (TCP) and hybrid (Primaria™) culture plates. Compositions and bond types were studied by X-ray photoelectron spectroscopy. Finally, the effect of each surface on cell adhesion and growth was assessed using human umbilical vein endothelial cells (HUVECs). Amine-containing surfaces manifested a wide [NH2] range, up to 8.9%. Hybrid surfaces, Primaria™ and L-PPE:O,N, showed lower [NH2] in spite of high [N], suggesting more varied and complex functionalities. Except for Parylene, all O- and NH2-rich surfaces promoted HUVEC adhesion and growth similarly, despite differing chemical compositions. Primaria™ showed the best cell behavior, but L-PPE:O,N did not reproduce this apparent synergistic effect. To conclude, both N- and O-rich surfaces displayed good cell-colonization properties, particularly plasma polymers, while 'hybrid' surfaces appear somewhat ambiguous and call for further investigation. [ABSTRACT FROM AUTHOR]

We report dielectric barrier discharge (DBD)-based atmospheric pressure (AP) plasma enhanced chemical vapor deposition (PECVD) experiments using argon carrier gas and ethyl lactate (EL) as the precursor molecule ('monomer'). As in our preceding research with other monomers, unprecedented precision and reproducibility is again demonstrated, here to create plasma polymerized (PP-EL) deposits. PP-EL is thought to be an excellent candidate for bio-medical applications on account of the non-toxic nature of resulting PP-EL deposits. We have shown that a narrow range of energy values absorbed from the plasma, Em, between roughly 21 and 42 eV/molecule, lead to PP-EL coatings of widely varying structural and physical properties, ones with controlled retention of chemical features of the EL monomer, and a predictable rate of degradation in aqueous media. [ABSTRACT FROM AUTHOR]

A large research reactor for dielectric barrier discharge (DBD) experiments at atmospheric pressure (AP) has been used with argon (Ar) carrier gas under constant plasma conditions ( f = 20 kHz, Va( f) = 8 kVp-p = 2.8 kVrms). Five esters, acrylates with differing number of unsaturations were used as 'monomers'; monomer flows, Fd, were at ‰ concentrations in the F = 10 standard liters per minute (slm) of argon. We earlier perfected and reported a method for measuring Eg, the energy dissipated per cycle of the applied a.c. voltage, and Δ Eg, the energy difference with and without monomer in the Ar flow. The latter, combined with Fd enable calculation of Em, the average energy absorbed from the plasma per monomer molecule. Plots of Em versus Fd and 1/ Fd yield much valuable information, for example about the role of CC and CC bonds in fragmentation and polymerization reactions. Fourier-transform infrared (FTIR) spectroscopy, spectroscopic ellipsometry (SE), and scanning electron microscopy (FEG-SEM) further enhance and complement data interpretation. [ABSTRACT FROM AUTHOR]

In the plasma polymerization literature, there has been an interest since at least the 1970s to correlate the structure of plasma polymer (PP) deposits with plasma parameters during deposition, most particularly with the energy input per monomer molecule, Em. In our two laboratories, we have developed methods for measuring Em (or somewhat equivalent, Ea) in low- (LP) and atmospheric-pressure (AP) discharge plasmas. In this article we propose a new parameter, the so-called energy conversion efficiency, ECE, which permits direct comparison of LP and AP experiments. This is done for the case of three model monomer compounds, ethane, acetylene, and acrylic acid (AAc). 'Critical' energy values that demarcate ECE regimes separating different fragmentation/reaction mechanisms agree remarkably well for all three monomers examined; resulting Em (or Ea) values are correlated with specific mechanisms, and the numerical results are convincingly supported by data from the chemical literature. [ABSTRACT FROM AUTHOR]

It has come to the authors’ attention that Figure in the article by B. Nisol et al. ( https://doi.org/10.1002/ppap.201500161, published in Plasma Process. Polym. 2016, 13, 557) displayed an erroneous result. An error occurred in the Matlab® code while carrying out the transfer of the energy measurement methodology to a larger DBD reactor. This erratum is published to correct this. [ABSTRACT FROM AUTHOR]

A large research reactor for performingdielectric barrier discharge (DBD) experiments at atmospheric pressure (AP) has been used with argon (Ar) carrier gas under constant plasma conditions ( f = 20 kHz, Va( f) = 8 kVp-p = 2.8 kVrms). Various permanent gases (H2, O2, N2, light hydrocarbons) and some heavier organic molecules were introduced as reactive 'dopant' flows, Fd, at ‰ concentrations in the F = 10 standard liters per minute (slm) flow of argon. We have earlier perfected and reported a method for measuring Eg, the energy dissipated per cycle of the applied a.c. voltage, and Δ Eg, the energy difference with and without reactive dopant in the Ar flow. The latter and Fd permit calculation of Em, the energy absorbed from the plasma by each dopant molecule. Plots of Em versus Fd and 1/ Fd yield much valuable information about excitation, fragmentation, and polymerization in the DBD plasma environment. Optical emission (OES) and Fourier-transform infrared (FTIR) spectroscopies help to further enhance and complement interpretation of measured data. [ABSTRACT FROM AUTHOR]

A large reactor for performing dielectric barrier discharges (DBD) experiments at atmospheric pressure (AP) has been built and tested. The area of electrodes is more than 40 times greater than that of a small DBD cell, in which we have perfected a method formeasuring Eg, the energy dissipated per cycle of the applied a.c. high voltage, Va( f). This methodology has been successfully applied to plasma polymerization experiments on the larger system, using volatile organic precursors (dopants) at ‰ concentrations in 10 standard liters per minute of argon (Ar). We measured Δ Eg, the energy difference with and without dopant, for Va( f) ∼ 3 kVrms (20 ≤ f ≤ 40 kHz). From Δ Eg we then derived Etot/ N, the energy per molecule, and observed surprisingly good agreement with data published in the literature relating to low-pressure (LP) plasmas. [ABSTRACT FROM AUTHOR]

Plasma polymerized coatings (PP) are increasingly used for biomedical applications in contact with body fluids. We optimized and studied the stability, mechanical properties, and adhesion in air and aqueous media of amine (NH2)-rich PP in low-pressure r.f. plasma from [NH3/C2H4] mixtures (L-PPE:N). Quartz crystal microbalance with dissipation monitoring (QCM-D) revealed partial dissolution or water-uptake (swelling) in real-time in various solutions, which helped identify the best gas mixture ratio for compromise between stability and high concentration of (NH2) groups. Nanoindention revealed strong decrease of Young's modulus and hardness in water. Finally, a Cross-Hatch peel test was used to optimize L-PPE:N adhesion on poly(tetrafluoroethylene) (PTFE): plasma pre-treatment prevented both dry and wet delamination. [ABSTRACT FROM AUTHOR]

Aligned electrospun poly(ethylene terephthalate) (ePET) nanofiber mats have been fabricated, which mimic the media layer of arteries. We used three different plasma etching techniques to bring their mechanical and surface properties in line with those of natural blood vessels: (i) atmospheric pressure ('HP') corona discharge in air; (ii) low-pressure radio-frequency plasma ('LP') and (iii) microwave plasma asher, (ii) and (iii) in pure oxygen (O2), or O2 mixture with Ar or CF4. (iii) gave substantial reduction in Young's modulus after as little as 5 min. treatment in O2, without damage to the fibers. Changes in surface composition and drastic improvement in wettability/wicking were also observed, which resulted in promoting adhesion and growth of smooth muscle cells (SMCs). [ABSTRACT FROM AUTHOR]

Thromboelastography uses cups and pins made of Cyrolite® plastic to analyze the rate of fibrin clot formation in blood samples. In this study, TEG cups and pins were modified by 4 distinct coating types using plasma-enhanced chemical vapor deposition (PECVD): carboxylated, amine-rich, hydrophobic, SiO2, and analyzed for surface chemistry and wettability. We tested the hypothesis that the coagulation kinetics of recalcified citrated blood plasma is controlled by surface chemistry, in the absence of clot activator. Only carboxylated surfaces became negatively charged upon wetting, and accelerated clot formation in a highly reproducible manner, whereas Cyrolite® and the other coatings had delayed and unpredictable clotting times. These data are consistent with a model whereby carboxylated surfaces selectively adsorb and activate factor XII while repelling other more abundant anionic blood proteins, resulting in reproducible clot kinetics. [ABSTRACT FROM AUTHOR]

Low-temperature plasma (LTP) science and technology are rapidly establishing their place in agriculture, with already existing or envisaged future commercial applications in (i) sustainable fertilizer production, (ii) food safety "from farm to fork", and (iii) in reducing pollution and pathogens. On-demand local fertilizer production or pathogen inactivation at the farm by LTP technology will reduce the need for complex logistics. This current S.I. consists of one review article and 14 original research papers, focusing on state-of-the-art LTP applications in agricultural and food-related fields, ranging from the basics of activating air and water by electrical discharges and the treatment and decontamination of seeds and plants, to LTP use as a food processing technology. [Extracted from the article]

The electrical discharge characteristics of a large‐area experimental dielectric barrier discharge in argon–hexamethyldisiloxane mixtures containing up to about 1,600 ppm of the monomer is analysed by means of electrical measurements and numerical modelling. A time‐dependent, spatially one‐dimensional fluid model is employed, taking into account the spatial variation of the discharge plasma between the two plane‐parallel dielectrics covering the electrodes. Reasonable agreement between electrical measurements and modelling results is generally found for the gap voltages and discharge currents. Remaining differences between the measured and calculated electrical energy dissipated in the plasma per period are discussed. [ABSTRACT FROM AUTHOR]

Plasma-assisted microfabrication has been a topic of capital importance in the evolution of plasma science and technology, especially since the 1970s. To a large extent, one can associate this trend of growth with "Moore's Law", the observation that the number of transistors in a dense integrated circuit doubles about every 2 years. Currently, the overall performance of computer chips is limited by energy consumption and data communication speeds among the CPUs, caches, memories, and storage devices. [Extracted from the article]

An introduction is presented in which the editor discusses various topics within the issue including article on Innovative Analytical Techniques for Plasma Polymers, Plasma Processing and Moore's Law, and Plasma-based Decontamination.

The method developed for fundamental understanding of energetic exchanges between monomer molecules and argon carrier gas in a dielectric barrier discharge (DBD) has previously proven merit. In this seventh article related to this methodology, research has been extended to a new family of precursors: anhydrides. Monomers (typically ‰) were mixed with 10 slm of Ar in a 20 kHz, 8 kV (peak‐to‐peak) DBD corresponding to an energy per cycle of 1600 μJ for pure Ar. For each of the investigated monomers Em, the energy absorbed per molecule was plotted as a function of precursor flow rate. The influence of chemical structure (C/O ratio, unsaturation) has been investigated and compared with previous data for other types of precursors. Thin plasma polymer coatings were deposited; in addition to measuring deposition rates, we also present relationships between Em values, spectro‐ellipsometric and FTIR measurements. [ABSTRACT FROM AUTHOR]

We report experiments in which reactive oxygen species (ROS) from a 20 kHz HV discharge in Ar/O2 (90/10) gas mixture at atmospheric pressure were directly bubbled into highly concentrated aqueous suspensions of cyanobacteria Dolichospermum, green algae Scenedesmus and BMAA toxin, simulating extreme algal blooms. It has been found that even quite short treatment durations, up to 6 min, could greatly reduce the numbers of viable cells and completely destroy the BMAA toxin. Perhaps even more important, "plasma‐activated water" (PAW) was found to continue its effectiveness after 24 h, even 4 days after terminating the discharge. We report the outstanding effects of "plasma‐activated water" (PAW), obtained with Ar/O2 (90/10) atmospheric pressure discharges generated at water/bubbles interfaces, on suspensions of cyanobacteria Dolichospermum, green algae Scenedesmus and BMAA toxin, simulating extreme algal blooms. Quite short treatment durations (up to 6 min) could greatly reduce the numbers of viable cells and completely destroy the BMAA toxin. Perhaps even more important, PAW was found to continue its effectiveness even 4 days after terminating the discharge. [ABSTRACT FROM AUTHOR]

The article offers information on the changes that the journal have implemented beginning in 2014. It includes the publication of the journal as an electronic-only (e-only) journal, the publication of a newsletter to subscribing institutions and publishing updates and short abstracts as part of its effort to improve contact with readers and other initiatives as part of the 10th anniversary celebrations, such as the publication of the booklet "Best of Plasma" which appeared in July 2014 issue.

The author presents information on the 11th anniversary of the journal. The journal was debuted by the Editors-in-Chief Riccardo d'Agostino, Pietro Favia, Christian Oehr, and Michael R. Wertheimer. It includes all areas of state-of-the-art plasma science, plasma sources, and processes. Its limitation is its concentration on low temperature plasmas.

Cover: Thromboelastography (TEG) measures the clot time and tensile strength of blood samples. TEG cups and pins were modified with 4 distinct PECVD coatings to analyze mechanisms of blood plasma coagulation through the contact pathway. Only carboxylated anionic surfaces produced a faster and highly controlled clot kinetics compared to the bare commercial Cyrolite® methacrylate polymer. Further details can be found in the article by Caroline Hoemann et. al. on page 817. [ABSTRACT FROM AUTHOR]