On the Possibilities of Straightforward Characterization of Plasma Activated Water

Plasma Chemistry and Plasma Processing - Plasma activated deionized water from a hot arc 150 W PAW synthesizer has been analyzed for nitrite, nitrate and peroxide densities. Observed nitrite and...     

Inactivation of <Emphasis Type="Italic">Shewanella putrefaciens</Emphasis> by Plasma Activated Water

Plasma activated water (PAW) generated by atmospheric-pressure air microplasma arrays is a solution containing a variety of reactive species. Here we investigate the effects of different applied voltage and water-activated time on bactericidal activities against Shewanella putrefaciens (S. putrefaciens). Our measurements showed that the sterilization efficiency of S. putrefaciens by PAW could be up to 2.0 Log Reduction. Scanning electron microscopy image and DNA concentration measurement showed that the S. putrefaciens cells were damaged and deformed due to the PAW treatment. The physicochemical properties of PAW treated by different applied voltage and water-activated time were evaluated, including pH value, initial PAW temperature, and the concentrations of plasma-activated species, such as H₂O₂, NO ₃ ^? , NO ₂ ^? , and O₃. Analysis indicates that the sterilization efficiency of S. putrefaciens treated by PAW was mainly determined by H₂O₂ concentration and pH value of PAW. This study provides a basis for the PAW potential applications in the disinfection of rotten food.     

Effect of Plasma Activated Water on Selected Chemical Compounds of Rocket-Salad (Eruca sativa Mill.) Leaves

Plasma activated water (PAW) has proven to be a promising alternative for the decontamination of rocket leaves. The impact of PAW on the volatile profile, phytosterols, and pigment content of rocket leaves was studied. Leaves were treated by PAW at different times (2, 5, 10, and 20 min). Compounds of the headspace were detected and quantified using GC–MS analysis. A total of 52 volatile organic compounds of different chemical classes were identified. Glucosinolate hydrolysis products are the major chemical class. PAW application induced some chemical modifications in the volatile compounds. Changes in the content of the major compounds varied with the increase or decrease in the treatment time. However, PAW-10 and -2 were grouped closely to the control. A significant decrease in the content of β-sitosterol and campesterol was observed after PAW treatment, except for PAW-10, which showed a non-significant reduction in both compounds. A significant increase in β carotene, luteolin, and chlorophyll b was observed after the shortest treatment time of PAW-2. A reduction in chlorophyll content was also observed, which is significant only at longer treatment, or PAW-20. Overall, PAW has proven to be a safe alternative for rocket decontamination.     

Nonadiabatic Ehrenfest molecular dynamics within the projector augmented-wave method

We derive equations for nonadiabatic Ehrenfest molecular dynamics within the projector augmented-wave (PAW) formalism. The discretization of the electrons is time-dependent as the augmentation functions depend on the positions of the nuclei. We describe the implementation of the Ehrenfest molecular dynamics equations within the real-space PAW method. We demonstrate the applicability of our method by studying the vibration of NaCl, the torsional rotation of H(2)C=NH(2)(+) in both the adiabatic and the nonadiabatic regimes, and the hydrogen bombardment of C(40)H(16).     

Seed Priming with Non-thermal Plasma Modified Plant Reactions to Selenium or Zinc Oxide Nanoparticles: Cold Plasma as a Novel Emerging Tool for Plant Science

Plasma Chemistry and Plasma Processing - This research explored the capability of seed priming with the non-thermal plasma to modify reactions of Melissa officinalis, an important medicinal plant,...     

Non-thermal Plasma as a Priming Tool to Improve the Yield of Pea in Outdoor Conditions

Seed priming is a pre-treatment of seeds leading to the improvement of their germination, the plant growth, and the product yield. In this study we investigated the possibility of the use of non-thermal plasma operating in atmospheric pressure air for seed priming with the objective to improve the yield of pea seeds. Two priming ways were used: an indirect way by using plasma activated water (PAW) generated by the transient spark discharge with water electrospray or the glow discharge batch treatment and a direct exposure of seeds to the pulsed corona discharge. After treatment, the seeds were planted in the outdoor field for about 14 weeks until harvest. The direct plasma treatment resulted in two key results: the strong effectiveness of the pulsed corona plasma improving the yield, and the long-term effect of the plasma seed treatment. The results of the indirect treatment showed that the pea plants from the seeds primed using PAW gained some improved growth parameters, especially the number of seeds per pod and the total number of seeds per plant. The scanning electron microscopy analysis showed that PAW and direct treatment induced some morphology changes at the surface of the pea seeds. This study documents a long-term effect of non-thermal plasma seed priming and contributes to the plasma agriculture applications by suggesting the implementation of non-thermal plasma direct or indirect treatments into the field.

     

Air to H2-N2 Pulse Plasma Jet for In-Vitro Plant Tissue Culture Process: Source Characteristics

Plasma Chemistry and Plasma Processing - Plasma agriculture has been considered as a promising solution for sustainable and safe agri-food production. Its applications include germination...     

Non-thermal Plasma Activated Water for Increasing Germination and Plant Growth of Lactuca sativa L

Plasma Chemistry and Plasma Processing - Non-thermal plasma is widely considered as an effective technology for applications in agriculture. Particularly, numerous reports studies have highlighted...     

Ab initio molecular dynamics calculations to study catalysis

The modern versions of the density functional theory (DFT), especially those using the generalized gradient approximation (GGA), have reached (almost) chemical accuracy and thus can be applied to study problems of real chemical interest such as catalysis. The important equations for the DFT, the local density approximation (LDA), and GGA are given. The full-potential linearized augmented plane wave method (LAPW) is used to check the accuracy of GGA in solids. The basic concepts of the ab initio molecular dynamics (MD) method by Car and Parrinello and its recent implementation using the projector augmented Wave (PAW) method which use a similar augmentation as LAPW are described. PAW applications to ferrocene and beryllocene are summarized, which illustrate that vibrational or fluxional behavior are well described. Sodalite, an aluminosilicate, is discussed as a generic zeolite in comparison with gmelinite. A study of the dynamics of such a system allows the determination of, e.g., the proton stretch vibrations which can be related to infrared spectra. This is illustrated for the OH stretch vibration of the acid site in silicon-rich sodalite. With this methodology, we are able to study the interaction of methanol trapped inside the cage structure of silicon-rich sodalite and to gain new insight into crucial steps of catalytic reactions, namely, the hydrogen-bonding and the possible protonation in this system, or a proton-exchange reaction. The strategies for parallelizing the PAW code are outlined. © 1997 John Wiley & Sons, Inc.     

Proton motion and proton transfer in the formamidine-formic acid complex: an Ab initio projector augmented wave molecular dynamics study

An ab initio molecular dynamics study performed with the projector augmented wave method (PAW) on proton motion and (double) proton transfer in the formamidine-formic acid complex is reported. The PAW trajectories were calculated with a time interval of 0.12 fs, for a total evolution time period of 36ps, and for temperatures in the range 500-600 K. All proton-transfer processes start with a proton transition at the O-H...N group, and are followed by a second proton transition, either at the same group ("single crossing-recrossing transitions") or at the other group, namely the N-H...O group ("double proton transfers"). According to the delay between the two transitions (more or less than 15 fs), one may distinguish between "concerted" (42%) or "successive" (16%) single crossing-recrossing transitions, and between "simultaneous" (7%) or "successive" (35%) double proton transfers. Successive processes take place via a zwitterionic intermediate, which remains stable for up to approximately 120 fs ("ionic regions"). The findings are in excellent agreement with the results of ab initio (HF, MP2) and density functional theory (DFT; B3LYP, B3P86) calculations, according to which the zwitterionic intermediate that results from the first proton transition is a true local minimum. Furthermore, it is shown that the optimized geometries of stationary points (ground state, transition state, and zwitterion) comply well with corresponding average data obtained from the PAW trajectories for normal periods, crossover points, and ionic regions.     

Special Issue of Plasma Chemistry and Plasma Processing Scale-Up of Plasma Reactors for Bio,Chemical, Environmental,Materials, and Energy Applications

Plasma Chemistry and Plasma Processing -     

LOBSTER: Local orbital projections,atomic charges,and chemical-bonding analysis from projector-augmented-wave-based density-functional theory

We present an update on recently developed methodology and functionality in the computer program Local Orbital Basis Suite Toward Electronic-Structure Reconstruction (LOBSTER) for chemical-bonding analysis in periodic systems. LOBSTER is based on an analytic projection from projector-augmented wave (PAW) density-functional theory (DFT) computations (Maintz et al., J. Comput. Chem. 2013 , 34, 2557), reconstructing chemical information in terms of local, auxiliary atomic orbitals and thereby opening the output of PAW-based DFT codes to chemical interpretation. We demonstrate how LOBSTER has been improved by taking into account time-reversal symmetry, thereby speeding up the DFT and LOBSTER calculations by a factor of 2. Over the recent years, the functionalities have also been continually expanded, including accurate projected densities of states (DOSs), crystal orbital Hamilton population (COHP) analysis, atomic and orbital charges, gross populations, and the recently introduced k -dependent COHP. The software is offered free-of-charge for non-commercial research.     

The role of lignification in the resistance of plants to attack by pathogens

Reviews by Vance et al. (1980) and Friend (1981) contain details of and references to the earlier work on lignification in both cucumber and grasses that is briefly described below. The suggestion of Hijwegen in 1963 that active lignification could be a general resistance mechanism in plants arose from experiments in which it was found that lignin deposition was associated with the reaction of a resistant cultivar of cucumber to inoculation withCladosporium cucumerimum. More recently Hammerschmidt and Kuć (1982) have found that systemic resistance of cucumber, induced by pre-inoculation with eitherC. cucumerimum orColletotrichum lagenarium, was associated with the ability of the induced plants to produce lignin rapidly in response to a challenge inoculation with either fungus. They concluded that induced resistance may be similar to cultivar resistance. Hammerschmidt et al. (1982) also showed that induction inoculation gave enhanced peroxidase activity in protected plants, associated with the fast-moving anodic isoenzymes. Lignification, especially the formation of lignified papillae, seems to be a common reaction of grass plants to attempted infection by nonpathogens. This has been found in reed canary-grass,Phalaris arundinacea, and a range of grasses by Vance and Sherwood, and in wheat by Ride. In reed canary-grass, active lignification is associated with increases in the enzymes of phenolic acid biosynthesis, and in peroxidase with the appearance of one new isoenzyme. The inducible resistance response, together with the associated increases in enzyme levels, were inhibited by the protein synthesis inhibitor, cycloheximide. The difference in response of wounded wheat leaves to inoculation by the nonpathogenBotrytis cinerea and the pathogenSeptoria nodorum appears to be related to the speed of lignification. It was rapid in the former case, confining the fungus to the wounded area; in the latter, it was slower and the fungus was not restricted. Recent experiments indicate that the accumulation of phenolic compounds in cell walls is a major factor in the non-race-specific resistance of potato tuber discs toPhytophthora infestans and of the same cultivars toPhoma exigua var foveata (Ampomah, 1983; Ampomah and Friend, in preparation). Accumulation of these compounds, estimated either by the level of browning of discs or the intensity of blue-green staining with toluidine blue of the walls of the top layer of cells, was greater following inoculation of resistant than of susceptible cultivars. Treatment of discs with aminooxyacetic acid (AOA), which is an inhibitor of PAL activity in vivo, inhibited the deposition of the phenolic compounds and permitted the fungi to grow further through tuber tissue. After freezing the discs in liquid nitrogen and extracting with chloroform: methanol: water (CMW), the residue was extracted with phenol: acetic acid:water (PAW). The CMW extracts contained chlorogenic acid; its level was lower in inoculated than uninoculated tissue. δεi measurements indicated that phenolic compounds were present both in the dialyzed PAW extract and in the PAW residue. There was always more phenolic material in both extract and residue from the inoculated discs of both resistant and susceptible cultivars than from uninoculated discs; the levels were always higher in the resistant than in the susceptible discs. The presence of quinic acid in the PAW extracts indicates the possibility that they contain oxidized, polymerized chlorogenic acid. Such material is absent from the PAW residue that contains esterified hydroxy cinnamic acids. We are, as yet, unable to determine whether these acids are esterified to lignin, to carbohydrate, or to the hydroxy-aliphatic acids in suberin.     

Grid-Assisted Co-Sputtering Method: Background,Advancement, and Prospect

Plasma Chemistry and Plasma Processing - In this paper, the incorporation of auxiliary grids/electrodes into the design of the sputtering method is scrutinized by studying the impact of factors...     

Structural,electronic, elastic,thermodynamic and vibration properties of TbN compound from first principles calculations

We have predicted structural, electronic, elastic, thermodynamic and vibration characteristics of TbN, using density functional theory within generalized-gradient (GGA) apraximation. For the total energy calculation we have used the projected augmented plane-wave (PAW) implementation of the Vienna Ab initio Simulation Package (VASP). We have used to examine structure parameter in eight different structures such as in NaCl (B1), CsCl (B2), ZB (B3), Tetragonal (L1₀), WC (Bh), NiAs (B8), PbO (B10) and Wurtzite (B4). We have performed the thermodynamics properties for TbN by using quasi-harmonic Debye model. We have, also, predicted the temperature and pressure variation of the volume, bulk modulus, thermal expansion coefficient, heat capacities and Debye temperatures in a wide pressure (0–130 GPa) and temperature ranges (0–2000 K). Furthermore, the band structure, phonon dispersion curves and corresponding density of states are computed. Our results are compared to other theoretical and experimental works, and excellent agreement is obtained.     

Accurate hyperfine couplings for C59N

We identify the shortcomings of existing ab initio quantum chemistry calculations for the hyperfine couplings in the recently characterized azafullerene, C₅₉N. Standard gaussian basis sets in the context of all-electron calculations are insufficient to resolve the spin density near the cores of the atoms. Using the projector augmented wave (PAW) method implemented on top of a standard pseudo-potential plane-wave density-functional framework, we compute significantly more accurate values for the Fermi contact interaction.     

Conformational pathways of saturated six-membered rings. A static and dynamical density functional study

The conformation of the six-membered ring of pyranosyl sugars has pronounced effects on the physical and chemical properties of carbohydrates. We present a method to determine key features of the potential energy surfaces, such as transition states associated with the inversion pathways of the model compounds cyclohexane, tetrahydropyran, p-dioxane, m-dioxane, s-trioxane, and 2-oxanol. Finally, we make the first determination of the pathways for inversion of penta-O-methyl-alpha-D-glucopyranose and penta-O-methyl-beta-D-glucopyranose. For both anomers, a transition state with five coplanar atoms with appreciable (O)E character was found. The method is based on constrained Car-Parrinello ab initio molecular dynamics, as implemented in the projector augmented-wave (PAW) method. The constraints are derived from the normal modes of six-membered rings and are described in terms of the canonical conformations (1)C(4) chair, (1,4)B boat, and (O)S(2) skew-boat. The PAW derived trajectories are in agreement with previous suggestions in the literature that pseudorotation is an important feature of such conformational interconversions. The dynamic nature as well as the internal coordinate-based constraints provide a method which can reliably accommodate pseudorotation. To determine semiquantitative energies, we recalculate key conformations using standard quantum mechanical calculations while keeping the ring dihedral angles frozen at their values found in the dynamics. In all cases where experimental barriers are known, our results are in excellent agreement.     

六角多铁性HoMnO3的电子和能带结构

基于密度泛函理论(DFT)结合投影缀加平面波(PAW)方法, 运用广义梯度近似(GGA), 在考虑电子基态自旋阻挫非共线的磁性结构基础上, 研究了具有六角钙钛矿结构HoMnO₃材料的磁性、电子和能带结构, 并解释了相关实验结果. 结果表明: 当考虑Mn³⁺离子的电子自旋在平面内呈阻挫的三角非共线反铁磁(NAFM)排列时, 六角HoMnO₃的总能降低、能隙变大、磁矩增大、各原子的位置更接近于实验值, 电子态密度(DOS)分布具有与X光吸收谱测量更为一致的结果. 对非共线磁性结构计算得到的电子态密度和能带结构的分析发现, 实验中观察到的1.7和2.3 eV两个光学吸收峰都源于Mn³⁺离子3d与平面内O(3, 4) 2p形成的杂化态与Mn [3d_3z²-r²]之间的电子跃迁, 而Ho 5d空轨道与平面上的O(3, 4) 2p轨道之间在z方向的强烈杂化驱动HoMnO₃产生垂直于平面方向的铁电极化.     

Improvement of Seed Germination Rate,Agronomic Traits,Enzymatic Activity and Nutritional Composition of Bread Wheat (Triticum aestivum) Using Low-Frequency Glow Discharge Plasma

Plasma Chemistry and Plasma Processing - Plasma agriculture is an emerging field. In this report, we studied the effect of medium pressure (~?10&nbsp;torr) low-frequency...     

Effect of titanium,antimony, and ruthenium doping on tin dioxide adsorption properties. Quantum-chemical modeling

The influence of the composition of oxides supports on the specific electroactive surface area of Pt in the catalysts, the platinum nanoparticles dispersion, and Pt contents in the catalysts was studied. The Sb-doped SnO₂ oxides with various Sb-doping levels were prepared as a supports of platinum catalysts in polymer electrolyte membrane fuel cells. Density functional theory simulation of Ti, Sb, and Ru doping of tin dioxide and interaction of the doped surfaces with platinum cluster Pt₁₉ have been carried out. All calculations were performed in PBE exchange–correlation functional, with periodic boundary conditions and projector-augmented waves (PAW) basis set. The calculation results were compared with the experimental data X-ray diffraction and transmission electron microscopy (TEM). It was shown that Sb doping of tin dioxide (in quantity of less than 10%, that is, the quantity which cannot provoke significant defects of crystal structure of the supports) leads to a significant increase in a number of platinum clusters adsorbed from the colloidal solution onto the supports surface which results to an increase of the platinum cluster interaction with the supports. The calculated and experimental results are in close fit.