The ozone behavior on heated catalytic probe surfaces is examined in gas flow downstream of atmospheric-pressure dielectric barrier discharge ozonizers. Negative and positive variations in the probe voltage as a function of probe heating current enable one to discriminate catalytic dissociation of ozone at low temperatures and catalytic recombination of oxygen radicals at high temperatures, respectively, on the probe surface. The loss coefficient of ozone on the probe surface derived from the amount of heat removed by catalytic dissociation is of the order of 10 -4 , which increases with increasing probe temperature. The probe temperature decrease per ozone concentration by catalytic dissociation of ozone as a measure of measurement sensitivity increases with probe temperature and is measured typically in the range of 0.5-0.8 Kg -1 m 3 at ozone concentrations of 10 and 17 gm -3 , respectively, showing the applicability of a catalytic probe to a simple sensor body.

In various types of material treatments, we focus on soil treatment because the latest problems we face are residual toxins in soil and ground water which have been caused by the overuse of chemical pesticides and nitrogen fertilizers that are used to disinfect soil borne worms or virus and enhance plant's growth in agriculture. Since plasma in atmospheric air generates reactive oxygen species, the indirect application of plasma for soil treatment is one of the potential usages for large-scale soil treatment which is one of the disadvantages in direct plasma or laser processing. We propose the use of plasma derivative ozone alternative to chemical pesticides or fertilizers for clean agriculture. In this paper, the decomposition of soil organic matters by the ozone treatment was evaluated with Gas Chromatograph Mass Spectroscopy and soil acidity measurement. Furthermore, the effect of ozone treatment on living microorganisms in soil was studied with high molecular DNA measurement.

Ozone-mist sterilisation and a web-based sensing system for greenhouse agriculture were studied. Ozone of high concentration of around 70 g/m 3 was generated by surface dielectric barrier discharges with high-frequency power. The ozone was injected into water-mist to form ozone-mist matter in a closed glass chamber. Ozone and its mist treatments were performed in a closed chamber (400 mm in height × 500 mm in dia.) which is a model of the greenhouse. The sterilisation rate of pests (aphids) was investigated using the ozone-mist as well as gaseous ozone and chemical synthetics. The ozone-mist sterilisation rate of 90-100% was attained, which is comparable to that achieved by chemicals. A web-based management system combined with the analysing technology of the digital camera images of plant state was developed to predict plant growth and pest development in the greenhouse. It is shown that three colour channels (Red, Green, Blue: RGB) and the greenindex defined by the colour channels are useful to monitor plant growth on a website. Several vegetables were planted in the greenhouse (W: 3 m ×D: 4 m × H: 2 m) and observed by taking digital camera images during 63 days. The daily data of RGB and greenindex were immediately added by sending the real-time images to the remote site through the Internet. It is shown that the greenindex (2 G-R-B) gradually decreases from 42 days to 53 days after the saturated high value during 29 days and 42 days. A web-based greenhouse management system using the digital camera images has the potential to sense plant state in a greenhouse and offers an inexpensive means for small-scale rural farms.

The authors have proposed the extermination of soil worms such as nematodes and the acceleration of plant growth by ozone treatment of soil because agricultural chemicals cause environmental problems such as the generation of resistant bacteria and the increase of toxic residuals and nitrogen. So far, laboratory-scaled experiments proved the effectiveness of ozone treatment of soil using a surface barrier discharge for the extermination of soil worms and for the enhancement of plant growth. In this paper, a movable ozone treatment system was developed for up-scaled application to verify the effectiveness and availability of ozone treatment of ridges in an actual greenhouse. It was found that the weights of harvested Komatsuna, radish, and spinach cultivated at ozone treated ridges were improved due to the increased nitrogen nutrient of soil after the ozone treatment. Quantification using digital numbers of red, green, and blue colors for digital camera photographs of plants was also verified to evaluate the growth of plants during cultivation.

One of the practical usages of plasma in large-scaled agriculture is the indirect application of plasma by irradiating plasma derivative radicals. Since agricultural chemicals cause environmental problems, such as the generation of resistant bacteria and the increase of toxic residuals, we have proposed the extermination of soil worms and the acceleration of plant’s growth by the ozone treatment of soil. Here, we propose soil treatment using ozone, generated by a surface barrier discharge, as both roles of pesticides and fertilizers. To investigate the effectiveness of gaseous ozone for the extermination of soil worms, this paper researched the influence of ozone on representative nematodes of C. elegans. Furthermore, to evaluate the practical effectiveness of the ozone treatment of natural nematodes living in agricultural soil, natural andosol was treated by ozone and the survival rate of nematodes was analyzed statistically using the Baermann funnel extraction.

Recently, application of plasma technologies to the agricultural field has attracted much interest because residual pesticides and excessive nitrogen oxides contained in plants, soil, and groundwater have become a serious issue worldwide. Since almost all of the atmospheric discharge plasma generates ozone, the effects of ozone are among the key factors for their agricultural applications. We have proposed the use of ozone generated using surface barrier discharge plasma for soil disinfection or sterilization. In this work, the ozone consumption coefficient and diffusion coefficient in soil were measured by the ultraviolet absorption method. The pH(H2O) and amount of nitrogen nutrient in soil after ozone diffusion treatment were studied and plant growth was observed simultaneously. The effect of ozone treatment on the amount of DNA in soil was also investigated and compared with that determined from the obtained ozone consumption coefficient.

To apply plasma technologies for large-scaled and advanced agriculture, the indirect use of plasma is one of the possible ways to overcome the disadvantage of direct plasma application. The recent problems we face in agriculture are due to soil worm damages and residual chemicals that are used for the extermination of the soil worms or for the acceleration of plant growth. Here, we propose soil treatment using ozone, generated by a surface barrier discharge, performing the roles of both pesticides and fertilizers. To investigate the efficacy of ozone for the extermination of soil worms, this paper researched the influence of ozone on nematodes (C. elegans). Furthermore, to evaluate the effectiveness of ozone for plant growth, the growth of radishes planted in the ozone-treated ridge in an actual greenhouse was observed.

A simple heat flow model is established for numerical analysis of the effect of catalytic dissociation of ozone on electrode surface temperature in a coaxial cylindrical-type dielectric barrier discharge ozonizer. The amount of heat consumed by the ozone decomposition at the electrode surface is determined from the balance of heat flow among the discharge gas, electrode, and cooling water. Our calculation using the experimental data shows that the ozone decomposition by 1.6% in total ozone reaching the electrode surface is required to explain the observed temperature decrease from about 20 °C to 8 °C for a stainless steel electrode, while that by 4.5% is needed to explain the temperature decrease from about 20 °C to 19 °C for a copper electrode. The decomposition rates calculated in the discharge are about two orders of magnitude higher than those measured in gas flow downstream of a similar discharge.

In this study, influence of ozone treatment on physical properties of soil was investigated. We used a quartz container for ozone treatment of soil. The amount of soil used for treatment was 100 g. Treating time was 90 minutes. Flow rate of ozone gas was 1.5 L/min. We measured characteristics of soil such as inorganic nutrient (NO3-N, NO2-N, and NH4-N), pH(H2O), fungi, DNA of soil, and exchangeable bases (Ca, K, Fe, and Al) before and after ozone treatment.

Pollution of soil, ground water and crops becomes serious issues by overuse of pesticide and nitrogen fertilizer in the world. We applied plasma technology to generate ozone and proposed the use of ozone in agricultural field for solving these problems. Ozone was generated by oxygen plasma using a surface discharge. Characteristics of soil such as inorganic nutrients (NO3-, NO2-, and NH4+), pH(H2O), pH(KCl), amount of soil DNA are influenced by ozone treatment because ozone has several characteristics. In this study, andosol (100 g) samples were treated for different treating times which range from 1 to 60 min. We investigated influence of ozone treatment on characteristics of soil such as inorganic nutrients (NO3- and NH4+), pH(H2O). In addition, not only influence of ozone treatment on characteristics of soil but also influence of only oxygen treatment was investigated to compare with influence of ozone treatment.

In this study, the influence of ozone treatment on physical properties of soil with low ozone dose rate was investigated. Ozone was generated by oxygen plasma using a dielectric surface barrier discharge and injected into soil in a quartz container which is rotated by a motor. The amount of soil used for the treatment was 100 g. Treating time was 1 min. The ozone dose rate, which is defined as ozone dose weight per unit weight of soil, was 0.1 %. Flow rate of ozone gas was 1.5 L/min. We measured the characteristics of soil such as inorganic nutrient contents (NO 3 -N, NO 2 -N, and NH 4 -N), pH(H 2 O), amount of fungi (nitrite and nitrate bacteria), amount of DNA of soil, and amount of exchangeable base (Ca, K, Fe, and Al) with low ozone dose. We measured physical properties of soil among three samples for confirmation of measurement reproducibility. Content of NO 3 -N and NH 4 -N increased slightly by ozone treatment for 1 min., and subsequently maintained at a constant value with time. The pH(H 2 O) decreased just after ozone treatment. However, the pH(H 2 O) value recovered gradually with time by the buffering function.

Temperature variation of a catalytic metal surface exposed to ozone produced in an atmospheric-pressure dielectric barrier discharge is examined by using a very thin thermocouple. The metal sheet is heated initially to a certain temperature (T 1 ) using a resistive heater and, then, the ozone concentration is increased with the heater current unchanged. When (T 1 ) is room temperature, the temperature of the metal sheet remains almost constant independent of ozone concentration. When (T 1 ) is increased up to 80 °C, the temperature of the metal sheet decreases clearly with increasing ozone concentration due to enhanced catalytic dissociation of ozone at the metal surface. The rate of decrease in temperature for a stainless steel sheet is increased from nearly 0% to ~5.7$ % with increasing (T 1 ) from room temperature to 80 °C, while that for a platinum sheet is increased further to ~17.5$ % at 80 °C due to stronger catalytic activity of platinum. The results confirm that the sensitivity for ozone is improved with a stronger catalytic metal heated to a higher temperature as the sensor body.

In many locations, generation of electrical energy is restricted due to unfavorable logistic conditions. That limits introduction of new technologies, requiring electrical power including air, water and soil purification technologies. Small scale treatment installations supplied with electric energy from solar sources were proposed as a good example of zero-emission technology achieved with reasonable cost. Treatment process of agricultural samples, pathogens and pests based on ozone and advanced oxidation process was described.

A catalytic probe made of a nickel thin wire is introduced into the gas flow downstream of an atmospheric pressure dielectric barrier discharge ozonizer to examine the ozone dissociation process on a catalytic surface. The probe is placed downstream far from the discharge to avoid the influence of reactive species other than ozone. The measured voltage variation across the probe wire under a constant probe heating current is used as a measure of the temperature variation of the probe surface and the nearby gas temperature. The stainless steel and copper wire made probes are also used to examine the effect of catalytic activity. Experimental results show that, for a low probe heating current of 0.2 A, the temperature of the probe decreases with increasing ozone concentration almost independent of the probe materials due to catalytic dissociation of ozone, which removes heat of reaction from the probe. When the heating current is increased to 1.5 A, the temperature of the nickel probe increases with increasing ozone concentration due to thermal dissociation of ozone followed by surface catalytic recombination of oxygen radicals, which gives heat of reaction to the probe. On the other hand, the temperature of the stainless steel and copper made probes decreases with increasing ozone concentration despite the high heating current due mainly to the low catalytic activities. (C) 2013 Elsevier Ltd. All rights reserved.

Chemical contamination in plants, soil, and ground water has become serious by overuse of pesticides and nitrogen fertilizers in agriculture. We propose the use of ozone generated by atmospheric pressure plasma for soil disinfection as one of the plasma applications into agriculture. Because ozone has strong oxidation potential to decompose organic substances in soil, it is considered to be one of the candidates as potential alternative to both pesticide and nitrogen fertilizer. In this paper, fundamental studies on changes in acidity and amounts of nitrogen nutrients, bacteria, mold, and soil DNA remained in soil after ozone treatment were carried out with a system using a quartz chamber. Surface barrier discharge that operates in atmospheric oxygen was used in the system as the ozone generator. In addition, growth of radishes that seeded on soils in pots that were treated by ozone diffusion method was also evaluated.

ジカルボン酸ジオール系脂肪族ポリエステル(APE)生分解樹脂エマルションおよびポリビニルァルコール(PVA)の存在下において酢酸ビニル(VAc)の乳化重合を行なった。複合化されたエマルションの最低造膜温度は0℃となった。これはVAcの重合によりAPEとポリ酢酸ビニル樹脂(PVAc)が相互貫入高分子となり，APEの結晶性が阻害され，低いガラス転移温度の性質が発現し複合エマルションの造膜温度を低下させたものと考えられる。JISK6950の方法に従い複合エマルションの樹脂乾燥皮膜の生分解性をBOD測定で評価した結果，一般的に易分解性の目安とされる60%を超えるBOD/TOD値となった。生分解過程での生成物の分析からPVAcのPVA化が明確に認められた。この複合エマルションで木材を接着したところ接着剤として十分な凝集力を有していた。

In this study, influence of ozone treatment on physical properties of soil was investigated. We used a quartz container for ozone treatment of soil. The amount of soil used for ozone treatment was 300 g. Treating time was 30 min. Flow rate of ozone gas was 1.5 L/min. We measured characteristics of soil such as pH(H2O) and inorganic nutrient content (NO3-N, NO2-N and NH4-N) before and after ozone treatment. Exhaust ozone concentration from the quartz container was monitored with an ozone monitor. The temperature of soil was measured with a thermo-couple during treatment. Ozone amount reacted with soil was about 0.99 g when soil was stirred. Ozone amount was about 0.82 g when soil was not stirred. Contents of NO3-N and NH4-N increased by one order after treatment and subsequently kept a constant quantity. The pH(H2O) decreased drastically to strong acidic region (pH(H2O)=5.0) just after ozone treatment, which is too acidic for growth of crops. However, the pH(H2O) value recovered gradually with time.

We developed a portable ozone mist system for the pest control in a farm. Ozone has strong oxidation power and they seem effective for killing pests such as worms, and insects. To enhance their effect on the pest control, ozone gas is produced by the surface dielectric barrier discharge and mixed with water mist ejected from a nozzle. We investigated the killing effect of the ozone mist on aphids. The survival rate of the aphids was 3.3% for 5 sec treatment time.

Low temperature atmospheric pressure plasmas (LTPs) together with advanced oxidation processes (AOPs) are alternative to conventional chemical methods of soil decontamination. The processing of soil itself depends on several factors, like type of soil and pollutants, treatment technique, geological and atmospheric circumstances. In the paper problems of soil, water, buildings, farms, land, and housing contaminations after floods and ecological disasters have been introduced. Plasma aided techniques together with AOPs have been presented from the point of view of decontamination potential as well as their impact on soil properties and fertility. Additionally, nanosize biological phenomena occurring in DNA strands during ozonation were visualized. The reaction of ozone with DNA is essential to understand the sterilization in agricultural soil. The structural images of the DNA samples were taken with the atomic force microscopy (AFM). It was shown that highly concentrated ozone broke hydrogen bonding of nuclei bases of DNA in relatively short time.