Optimization and influence of multi-hollow surface dielectric barrier discharge plasma operating conditions on the physical quality of peanut

An experiment was conducted to investigate the effects of atmospheric pressure plasma generated by multi-hollow surface dielectric barrier discharges on physical quality of peanut (Arachis Hypogea L). Multi-hollow surface dielectric barrier discharge is a novel plasma device applicable in food industry applications due to the capacity of the generated plasma to treat the surface of food without changing the quality. Response surface methodology was used to optimize the plasma treatment for surface treatment as raw peanut forms over a range of power (10–40 W), air flow rate (0.5–20 L/min) and time (1–15 min). The weight loss, hardness, contact angle, color parameters, microstructure, and sensory quality evaluation were evaluated during plasma treatments and modeled by response surface methodology and compared the means. Second order polynomial model adequately described the plasma treated experimental data except for sensory attributes with an insignificant lack of fit (p > 0.05). The result revealed that extreme conditions caused a decrease in L*,b*, hardness, contact angle, increased weight loss, color change and changed the microstructure of the treated peanuts

Selective Plasma Etching of Polymer-Metal Mesh Foil in Large-Area Hydrogen Atmospheric Pressure Plasma

We present a novel method of surface processing of complex polymer-metal composite substrates. Atmospheric-pressure plasma etching in pure H2, N2, H2/N2 and air plasmas was used to fabricate flexible transparent composite poly(methyl methacrylate) (PMMA)-based polymer film/Ag-coated Cu metal wire mesh substrates with conductive connection sites by the selective removal of the thin (~10–100 nm) surface PMMA layer. To mimic large-area roll-to-roll processing, we used an advanced alumina-based concavely curved electrode generating a thin and high-power density cold plasma layer by the diffuse coplanar surface barrier discharge. A short 1 s exposure to pure hydrogen plasma, led to successful highly-selective etching of the surface PMMA film without any destruction of the Ag-coated Cu metal wires embedded in the PMMA polymer. On the other hand, the use of ambient air, pure nitrogen and H2/N2 plasmas resulted in undesired degradation both of the polymer and the metal wires surfaces. Since it was found that the etching efficiency strongly depends on the process parameters, such as treatment time and the distance from the electrode surface, we studied the effect and performance of these parameters

Photofragmentation laser-induced fluorescence of ozone : an in situ tool for precise mapping of ozone concentration in non-thermal plasmas

The absolute spatially resolved concentration of ozone has been determined in the near afterglow of a novel type of atmospheric multi-hollow barrier discharge using photofragmentation laser-induced fluorescence. The method consists of two steps: (i) photodissociation of O-3 to O(P-3) and O-2(X-3 Sigma(-)(g)) with considerable vibrational excitation; (ii) predissociation laser-induced fluorescence of the molecular fragment via the O-2 (B-3 Sigma(-)(u), v' = 0 <- X-3 Sigma(-)(g), v '' = 6) transition. Both processes happen during the same laser pulse, requiring the same excitation wavelength (approximate to 248 nm). The fluorescence signal has been calibrated by infrared absorption. The method allows in situ observation before the afterglow chemistry significantly affects the O-3 concentration, and is capable of revealing inhomogeneous ozone distributions in the reactor. (C) 2019 The Japan Society of Applied Physic

Cold atmospheric pressure plasma: simple and efficient strategy for preparation of poly(2-oxazoline)-based coatings designed for biomedical applications

Abstract Poly(2-oxazolines) (POx) are an attractive material of choice for biocompatible and bioactive coatings in medical applications. To prepare POx coatings, the plasma polymerization represents a fast and facile approach that is surface-independent. However, unfavorable factors of this method such as using the low-pressure regimes and noble gases, or poor control over the resulting surface chemistry limit its utilization. Here, we propose to overcome these drawbacks by using well-defined POx-based copolymers prepared by living cationic polymerization as a starting material. Chemically inert polytetrafluoroethylene (PTFE) is selected as a substrate due to its beneficial features for medical applications. The deposited POx layer is additionally post-treated by non-equilibrium plasma generated at atmospheric pressure. For this purpose, diffuse coplanar surface barrier discharge (DCSBD) is used as a source of “cold” homogeneous plasma, as it is operating at atmospheric pressure even in ambient air. Prepared POx coatings possess hydrophilic nature with an achieved water contact angle of 60°, which is noticeably lower in comparison to the initial value of 106° for raw PTFE. Moreover, the increased fibroblasts adhesion in comparison to raw PTFE is achieved, and the physical and biological properties of the POx-modified surfaces remain stable for 30 days

Structural and Optical Properties of Luminescent Copper(I) Chloride Thin Films Deposited by Sequentially Pulsed Chemical Vapour Deposition

Sequentially pulsed chemical vapour deposition was used to successfully deposit thin nanocrystalline films of copper(I) chloride using an atomic layer deposition system in order to investigate their application to UV optoelectronics. The films were deposited at 125 degrees C using [Bis(trimethylsilyl)acetylene](hexafluoroacetylacetonato)copper(I) as a Cu precursor and pyridine hydrochloride as a new Cl precursor. The films were analysed by XRD, X-ray photoelectron spectroscopy (XPS), SEM, photoluminescence, and spectroscopic reflectance. Capping layers of aluminium oxide were deposited in situ by ALD (atomic layer deposition) to avoid environmental degradation. The film adopted a polycrystalline zinc blende-structure. The main contaminants were found to be organic materials from the precursor. Photoluminescence showed the characteristic free and bound exciton emissions from CuCl and the characteristic exciton absorption peaks could also be detected by reflectance measurements

Deposition of MoSe2 flakes using cyclic selenides

The currently limited portfolio of volatile organoselenium compounds used for atomic layer deposition (ALD) has been extended by designing and preparing a series of four-, five- and six-membered cyclic silylselenides. Their fundamental properties were tailored by alternating the ring size, the number of embedded Se atoms and the used peripheral alkyl chains. In contrast to former preparations based on formation of sodium or lithium selenides, the newly developed synthetic method utilizes a direct and easy reaction of elemental selenium with chlorosilanes. Novel 2,2,4,4-tetraisopropyl-1,3,2,4-diselenadisiletane, which features good trade-off between chemical/thermal stability and reactivity, has been successfully used for gas-to-solid phase reaction with MoCl5 affording MoSe2. A thorough characterization of the as-deposited 2D MoSe2 flakes revealed its out-of-plane orientation and high purity. Hence, the developed four-membered cyclic silylselenide turned out to be well-suited Se-precursor for ALD of MoSe2

Atomic Layer Deposition of MoSe2 Using New Selenium Precursors

Among the emerging 2D materials, transition metal chalcogenides are particularly encouraging as alternative semiconducting graphene-like nanomaterial. Recently, 2D MoSe2 has been gaining interest due to its intriguing properties, in many ways exceeding those of the extensively studied MoS2. The deposition of 2D nanomaterials in a conformal and uniform fashion on complex-shaped nanostructures is highly appealing but only achievable by atomic layer deposition (ALD). Unfortunately, the synthesis of MoSe2 by ALD is hindered by a current substantial lack of feasible Se precursors. In this work, we synthesized a set of alkysilyl (R3Si)2Se and alkylstannyl (R3Sn)2Se compounds and studied their suitability as Se ALD precursors. Thus, ALD processes carried out using MoCl5 as Mo precursor counterpart were followed by an extensive characterization of the as deposited material. The corresponding results revealed successful deposition of MoSe2 nanostructures on substrates of different nature with dominant out-of-plane orientation. Eventually, the growth evolution of the MoSe2 during the very early ALD stage was studied and described, displaying concomitant in-plane and out-of-plane MoSe2 growth. All in all, a set of Se suitable precursors presented herein paves the way for the deposition of 2D MoSe2 with all the own ALD benefits and allow the further study of its promising properties in a wide number of applications

Depozice atomárních vrstev MoSe2 nanodestiček na povrch TiO2 nanotrubek, fotokatalytický rozklad barviv a elektrokatalytický vývoj vodíku na těchto površích

Herein, hierarchical MoSe2/1D TiO2 nanotube layer structure was successfully fabricated in a simple and fast fashion and its photocatalytic and electrocatalytic properties were assessed. The novelty of this work lies in the utilization of Atomic Layer Deposition (ALD) technique to deposit MoSe2 nanosheets on 1D TiO2 nanotube layers. The photoelectrochemical and photo- and electrocatalytic properties were explored and optimized as a function of the MoSe2ALD cycles. ALD allowed precise control on MoSe2 nanosheet size, and in turn, on the surface structure, which is pivotal for efficient catalysts. The MoSe2 nanosheets grew on both inner and outer 1D TiO2 nanotube surface mainly perpendicularly oriented, maximizing the exposed active edges, an essential aspect to fully exploit the MoSe2 photo- and electrochemical properties. Outstanding photo- and electrocatalytic activity were recorded in both dye organic pollutant degradation and hydrogen evolution reaction applications, respectively. The excellent photocatalytic and electrochemical activity stems from the synergy between tailored ALD loading of MoSe2 nanosheets on 1D TiO2 nanotubular structure with high surface/volume ratio, which provided fast electron transfer and easy access to the MoSe2 active edges, boosting the catalytic activity.V této práci jsme vytvořili hybridní strukturu MoSe2 nanodestiček na 1D TiO2 nanotrubicových vrstvách jednoduchým a rychlým způsobem. Novost naší práce spočívá ve využití techniky depozice atomárních vrstev (ALD) pro deponování MoSe2 nanodestiček na 1D TiO2 nanotrubicové vrstvy. U výsledných materiálů jsme zhodnotili výsledné fotokatalytické a elektrokatalytické vlastnosti v závislosti na počtu použitých depozičních ALD cyklů. ALD umožnilo velmi precizní kontrolu velikosti MoSe2 nanodestiček a také mělo vliv na na jejich povrchovou strukturu, která je klíčový pro výsledné vlastnosti. Tyto nanodestičky rostly jak uvnitř trubic, tak na jejich externím povrchu, kolmo orientované k trubicovým stěnám, což vedlo k maximálnímu možnému obnažení aktivních center na hranách nanodestiček. Velmi vysoké foto- a elektrokatalytické aktivity byly dosaženy pro rozklad modelových organických látek a pro vývoj vodíku, respektive. Tyto výkony pramení ze synergie mezi MoSe2 nanodestičkami a 1D TiO2 nanotrubicovými vrstvami s vysokým poměrem dostupného povrchu/objemu, což umožnilo velmi dobrý přenos elektronů a snadný přístup reaktantů k aktivním centrům MoSe2 nanodestiček