Over-fertilization Research Articles

Comparison of Plasma-Polymerized Thin Films Deposited from 2-Methyl-2-oxazoline and 2-Ethyl-2-oxazoline: I Film Properties.

Poly(2-oxazoline) is a promising new class of polymeric materials due to their antibiofouling properties and good biocompatibility. Poly(2-oxazoline) coatings can be deposited on different substrates via plasma polymerization, which can be more advantageous than other coating methods. The aim of this study is to deposit poly(2-oxazoline) coatings using a surface dielectric barrier discharge burning in nitrogen at atmospheric pressure using 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline vapours as monomers and compare the film properties. For the comparison, the antibacterial and cytocompatibility tests were peformed according to ISO norms. The antibacterial tests showed that all the deposited films were highly active against Staphylococcus aureus and Escherichia coli bacteria. The chemical composition of the films was studied using FTIR and XPS, and the film surface's properties were studied using AFM and surface energy measurement. The cytocompatibility tests showed good cytocompatibility of all the deposited films. However, the films deposited from 2-methyl-2-oxazoline exhibit better cytocompatibility. This difference can be explained by the different chemical compositions and surface morphologies of the films deposited from different monomers.

Antibacterial Thin Films Deposited from Propane-Butane Mixture in Atmospheric Pressure Discharge.

Antibacterial coatings on biomedical instruments are of great interest because they can suppress bacterial colonization on these instruments. In this study, antibacterial polymeric thin coatings were deposited on teflon substrates using atmospheric pressure plasma polymerization from a propane-butane mixture. The plasma polymerization was performed by means of surface dielectric barrier discharge burning in nitrogen at atmospheric pressure. The chemical composition of plasma polymerized propane-butane films was studied by energy-dispersive X-ray spectroscopy (EDX) and FTIR. The film surface properties were studied by SEM and by surface energy measurement. The EDX analysis showed that the films consisted of carbon, nitrogen and oxygen from ambient air. The FTIR analysis confirmed, in particular, the presence of alkyl, nitrile, acetylene, imide and amine groups. The deposited films were hydrophilic with a water contact angle in the range of 13-23°. The thin film deposited samples were highly active against both S. aureus and E. coli strains in general. On the other hand, the films were cytocompatible, reaching more than 80% of the cell viability threshold compared to reference polystyrene tissue.

Atmospheric Pressure Plasma Polymerized 2-Ethyl-2-oxazoline Based Thin Films for Biomedical Purposes.

Polyoxazoline thin coatings were deposited on glass substrates using atmospheric pressure plasma polymerization from 2-ethyl-2-oxazoline vapours. The plasma polymerization was performed in dielectric barrier discharge burning in nitrogen at atmospheric pressure. The thin films stable in aqueous environments were obtained at the deposition with increased substrate temperature, which was changed from 20 C to 150 C. The thin film deposited samples were highly active against both S. aureus and E. coli strains in general. The chemical composition of polyoxazoline films was studied by FTIR and XPS, the mechanical properties of films were studied by depth sensing indentation technique and by scratch tests. The film surface properties were studied by AFM and by surface energy measurement. After tuning the deposition parameters (i.e., monomer flow rate and substrate temperature), stable films, which resist bacterial biofilm formation and have cell-repellent properties, were achieved. Such antibiofouling polyoxazoline thin films can have many potential biomedical applications.

Current interruption performance of ultrahigh-pressure nitrogen arc

In this paper, the influence of gas filling pressure on the current interruption performance of different switch configurations with electric arcs burning in nitrogen has been experimentally investigated. A synthetic circuit generating a current of 130 A at 190 Hz is used and the initial rate of rise of recovery voltage just after current zero is varied from 9.8 V/µs to 84.9 V/µs. To evaluate the effect of forced gas flow on current interruption performance, three different test arrangements are investigated: a simple contact configuration with a free-burning arc, a contact and a cylindrical nozzle setup (tube-constricted arc), and finally a self-blast arrangement where the arc is cooled by a gas flow near current zero. In each arrangement, three different filling pressures are mainly studied: 1, 20, and 40 bar, the latter being in the supercritical region. In all cases, the interelectrode gap is fixed at 50 mm. It is observed that the interruption performance deteriorates with increased filling pressure in the absence of forced gas flow. A higher post-arc current is observed for the arcs burning at high filling pressures (i.e. 20 and 40 bar) compared to at atmospheric pressure in cases with no or little forced cooling. On the other hand, a forced gas flow near the current zero reduces the post-arc current and improves the interruption performance also at high filling pressures. Little effect of the supercritical state on the interruption performance of nitrogen is observed. Under the above-mentioned test conditions, the majority of the failures at high filling pressure are observed to be of thermal re-ignition type.

Manure nutrient application on a Chinese dairy farm with arable land: A case study based on Dutch experience of equilibrium fertilization

For a Chinese dairy farm with 2200 milking cows, the annual manure production and manure nutrients (nitrogen and phosphorus) were estimated. Gaseous nitrogen losses from cattle housing with scraped solid floors were based on on-farm measurements. Based on experiences from the Netherlands, nutrient levels in the solid and liquid fractions after slurry separation were estimated. On the basis of assumptions for nutrient losses during covered lagoon storage and land application of the liquid fraction, nitrogen and phosphorous fertilization rates were calculated for the 67 hm2 of agricultural land that receive the liquid fraction by gravity irrigation. The results show that the application rates of nitrogen and phosphorous significantly exceed the crop needs, which will probably result in losses to soil and water. In order to aim for a balance between nutrient application and crop needs and, as such, reduce environmental harm, the authors recommend to establish application standards for nitrogen and phosphorous on arable land in China and to formulate farm-specific Nutrient Management Plans. Keywords: dairy manure, nutrient balance, dairy farm, over-fertilization, nutrient application standard, environmental protection DOI: 10.25165/j.ijabe.20171004.3082 Citation: Melse R W, de Buisonje F E, Qiao W, Dong R J. Manure nutrient application on a Chinese dairy farm with arable land: A case study based on Dutch experience of equilibrium fertilization. Int J Agric & Biol Eng, 2017; 10(4): 182–188.

Deposition of hard thin films from HMDSO in atmospheric pressure dielectric barrier discharge

An atmospheric pressure dielectric barrier discharge burning in nitrogen with a small admixture of hexamethyldisiloxane (HMDSO) was used for the deposition of thin organosilicon films. The thin films were deposited on glass, silicon and polycarbonate substrates, and the substrate temperature during the deposition process was increased up to values within the range 25–150 °C in order to obtain hard SiOx-like thin films. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. The deposited films were characterized by the Rutherford backscattering and elastic recoil detection methods, x-ray photoelectron spectroscopy, infrared spectroscopy measurements, ellipsometry and the depth sensing indentation technique. It was found that the films' properties depend significantly on the substrate temperature at deposition. An increase in substrate temperature from 25 to 150 °C led to an increase in film hardness from 0.4 to 7 GPa and the film chemical composition changed from CHxSiyOz to SiOxHy. The films were transparent in the visible range.

Deposition of organic polymers at higher substrate temperatures in atmospheric pressure glow discharge

The atmospheric pressure glow discharge burning in nitrogen with small admixture of organosilicon compounds such as hexamethyldisilazane (HMDSN) or hexamethyldisiloxane (HMDSO) was used for the deposition of thin organosilicon polymer films at deposition temperatures up to 120 °C. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. Mechanical properties of deposited films were characterised by depth sensing indentation technique, optical properties were measured by means of ellipsometry. The films were polymer-like, transparent in visible range and without pinholes.

Deposition of thin organosilicon polymer films in atmospheric pressure glow discharge

The atmospheric pressure glow discharge burning in nitrogen with small admixture of organosilicon compounds such as hexamethyldisilazane or hexamethyldisiloxane was used for the deposition of thin organosilicon polymer films. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. The deposited films were characterized by atomic force microscopy, x-ray photoelectron spectroscopy, infrared transmission measurements, ellipsometry, depth sensing indentation technique and contact angle measurements. The films were polymer-like, transparent in the visible range, with uniform thickness and without pinholes. The film hardness varied from 0.3 to 0.6 GPa depending on deposition conditions, the elastic modulus was in the range 15–28 GPa and the surface free energy was in the range 26–45 mJ m−2. The studied films exhibited good adhesion to the substrate.

Arc velocity and cathode erosion rate in a magnetically driven arc burning in nitrogen

Measurements of the arc velocity and of the erosion rate are reported for a copper cathode. The 100 A arc, burning in nitrogen, is driven by a magnetic field B, varying from 5.1 to 171.0 mT, between concentric copper electrodes having an inter-electrode gap of 4 mm. The arc velocity varied with B0.60 throughout the range investigated. The erosion rates dropped from 9.0 to 1.0 mu g C-1 as the arc velocity was increased from 15 to 135 m s-1.

Structure and extinction of counterflow diffusion flames above condensed fuels: Comparison between poly(methyl methacrylate) and its liquid monomer, both burning in nitrogen–air mixtures

AbstractSince poly(methyl methacrylate) is known to depolymerize largely to its monomer when heated, the chemical kinetics in the gaseous diffusion flame produced by this polymer in a fire may coincide with that of burning liquid methyl methacrylate. To test this hypothesis, flat diffusion flames were probed and extinguished adjacent to surfaces of each of these fuels. Profiles of temperature and of concentrations of stable chemical species are reported, as are gas velocities of approach flow required to produce extinction for various oxygen/nitrogen ratios of the stream. Results revealed structural differences attributable to differing thermal properties of the fuels. Many fuel species were observed in the gas phase, their profiles being partially rationalized on the basis of a suggested decomposition mechanism for gaseous methyl methacrylate. Overall kinetic parameters for gasphase combustion, obtained by use of extinction results in a previously developed theory, are nearly the same for the polymer and monomer but appear to differ by amounts exceeding experimental uncertainties. It is suggested that this may be traced to small differences in fuel species leaving the condensed phase which, for the polymer, is covered by a thin, two‐phase region.

Temperature Distribution in a dc Free Burning Arc in Nitrogen with and without Addition of Li2CO3

The investigation of the lithium effect on the temperature distribution of the arc is presented. Measurements were carried out by the Schlieren interference method to about 4000°K. The arc free burning in nitrogen was observed and the results of temperature measurements, carried out with and without lithium addition, were presented. Lithium was added to the arc by anode evaporation. Temperature measurements in outer areas were connected to previously presented spectroscopical measurements in the central part of the arc. The lithium addition affects the increase of the electroconductive central part of the arc.

The effect of the plasma composition on characteristics of the d.c. arc—II: Arc in argon and arc in nitrogen with water vapour

The experimental and theoretical curves of the radial temperature distribution of the arc burning in argon, are compared with the corresponding curves in nitrogen. The theoretical curves are obtained by solving the E lenbaas-H eller energy balance equation according to Maecker. The model of the freely burning arc, under conditions usually applied in spectrochemical praxis, is considered. In accordance with theory and in comparison with the arc burning in pure nitrogen, the brilliant zone of arcs burning in argon has a steeper radial temperature distribution. If water vapour is added to an arc burning in nitrogen, the arc plasma is narrowed and the temperature increased. These experimental data can be interpreted theoretically from the solution of the energy balance equation.

The effect of the plasma composition on characteristics of the d.c. arc—IV: Influence of lithium on an arc in nitrogen

The radial temperature distribution of the arc burning in nitrogen was measured when a large quantity of Li 2CO 3 evaporates in the arc. In comparison to the radial temperature distribution of the arc burning in nitrogen alone, a smaller temperature gradient was obtained. This can be interpreted by taking the variation of the electron density into account when solving the E lenbaas-H eller equation for the plasma energy balance.

The effect of the plasma composition on characteristics of the d.c. arc—I: General discussion of the effect of the chemical reactions

The influence of chemical reactions among the components of the arc atmosphere on the radial temperature distribution is discussed. Their effect on other arc plasma characteristics and the spectrochemieal determination of elements in the arc is considered. The discussion is made in terms of the E lenbaas-H eller equation for the energy balance of the plasma. The equation is solved according to Maecker. The arc model is a freely burning arc, under conditions usually applied in spectrochemical practice. The role of dissociation energy is discussed on the basis of a theoretical model. Experimental and theoretical data for the radial temperature distribution of an arc burning in nitrogen are compared to check the appropriateness of the applied procedures.

The influence of additives on the reactions in hydrogen-chlorine flames

Studies have been made of the effect of a number of additives on the burning velocity of hydrogen-chlorine-nitrogen mixtures burning both in air and in nitrogen. The results have been expressed in such a way as to be independent of hydrogen-chlorine ratio used and to allow for possible changes in stoichiometry. With flames burning in air, all the additives studied exerted only inhibiting effects and shifted the position of maximum burning velocity from fuel-rich toward stoichiometric mixtures. With flames burning in nitrogen, however, certain additives showed quite large promotional influences, their order of effectiveness being: bromomethane>deuteromethane-d4>chloromethane>methane>acetylene. As the maximum burning velocity increased, the position of the maximum tended toward fuel-rich mixtures. n-Butane, isobutane, ethane and ethylene exerted only inhibiting effects and moved the position of maximum burning velocity toward fuel-lean mixtures. Additions of oxygen (and of dimethyl ether) caused initial inhibition followed by rapid promotion; the position of maximum eventually showed a large shift toward fuel-rich compositions. The strong promotional effects found with certain additives cannot be accounted for simply in terms of an increase in flame temperature. On the other hand, the observed reductions in burning velocity are consistent with a fall in flame temperature as a result of carbon radiation heat losses. The organic additives that exert promoting effects appear to be those that either break down to give free radicals which cause further chain propagation or form chlorocompounds which can do so. The strong promoting action of oxygen is ascribed to the occurrence of certain elementary steps involved in the hydrogen-oxygen reaction.

Calculation of a wall-stabilized argon arc with account for radiative energy transfer

It was shown experimentally in [1, 2] and in a study by E. I. Asinovskii and A. V. Kirillin reported at the Scientific Technical Conference of the High-Temperature Scientific Research Institute held in 1964 that the heat transfer mechanism in a wall-stabilized argon arc was not purely purely conductive at gas temperatures greater than 11 000° K. Asinovskii and Kirillin also showed that radiative energy transfer is the reason why similarity is lost when the current-voltage characteristics are constructed in dimensionless form. The radiation of an argon arc has been studied experimentally by a number of authors [3–5], Dautov [6] calculated an argon arc without allowing for radiation. In this article an argon arc stabilized by the cooled duct walls is calculated with account for radiation using theoretically computed relationships describing the transport properties of argon plasma. A large portion of the radiated energy pertains to spectral lines whose role has been studied by L. M. Biberman. The authors have used I. T. Yakubov's data on argon radiation published in the journal “Optics and Spectroscopy.” A method of calculation and data on argon plasma radiation are also given in [7]. Reference [8] deals with the problem of the role of radiation in an arc burning in nitrogen. In particular, the above-mentioned loss of similarity follows from the results of this work. However, the relationships used in this article to describe the transport properties of nitrogen plasma were obtained experimentally in [9].

Flame Zone Spectroscopy of Solid Propellants II Double Base Propellant JPN*

With the aid of the automatic-feed strand bomb previously described [ R. G. Rekers D. S. Villars , Rev. Sci. Instr.25, 424– 429 ( 1954)], spectra of JPN burning in nitrogen have been investigated over the visible and ultraviolet. Throughout the pressure range, 300 to 500 psi nitrogen, emission from the flame zone exhibits a continuous background which extends into the ultraviolet to approximately 3200 A. Accompanying this continuum are some of the more prominent lines of spectra due to sodium, potassium, calcium, copper, and iron. Calcium oxide bands in the 6260 region (orange system) and in the 5500 region (green system) have been identified. Furthermore, a multitude of weak lines is observed in the wavelength region, 4600 to 5800 A. Both the Swan and the high-pressure bands attributed to C2 appear to be present in this flame. The dividing line between flame and fizz zones does not appear to be sharp.No absorption in the visible region has been found in the fizz zone over the pressure range, 25 to 150 psi nitrogen. NO2 absorption originally noted has been shown to originate from the external atmosphere surrounding the flame. Absence of nitrogen dioxide from the fizz zone is highly significant with respect to theories of reaction mechanism, which usually assume as primary step the formation of nitrogen dioxide and a radical from a nitrate. The present demonstration indicates that formation of NO2 is a secondary reaction.