Low Temperature Plasma

Low temperature plasma nitriding can harden the surfaces of austenitic stainless steels without degrading corrosion resistance. It does so by formation of a non-equilibrium precipitation free layer: the so called ‘‘S phase’’ or ‘‘expanded austenite’’. Despite its very high nitrogen content, the S phase has no chromium nitrides that consume the dissolved chromium. 1–4)

In this study, plasma treatment showed a 5-log reduc- tion in S. mutans cells on the cover glass. This sig- nificant bactericidal effect decreased to a 3-log reduction when S. mutans was grown on the tooth surface. Although a 3-log reduction of S. mutans obviously rep- resents a high bactericidal effect, the residual bacteria could cause recurrent dental caries. Accordingly, as a new method to overcome this issue, we used gNPs in combination with low-temperature plasma to achieve a high level of effectiveness and rapid killing of S. mutans. In this study, we used 30-nm colloidal shaped gNPs. gNPs are well known for biosafety and uptake into the cell [17]. The shape and size of gNPs can be easily con- trolled [18], which has led to their widespread applica- tion in diagnostics [19], therapeutics, and drug delivery [20]. According to one study, the electric field at the adhesion point between gNPs and membrane was am- plified when gNPs attached to the surface of a nuclear membrane were exposed to plasma [21]. In an earlier study by our group, we showed that gNPs stimulated by plasma induced selective cancer cell death in melanoma and oral squamous carcinoma cells [22,23]. In the cur- rent study, gNPs were bound to S. mutans cells walls, and no alterations were observed in the S. mutans cells. Plasma treatment of S. mutans was more effective against gNP-attached cells than against the gNP-free ones. TEM images showed severe cell wall damage with plasma treatment. Furthermore, the combination treat- ment of gNPs and plasma led to cell wall rupture, such that most intracellular components were released. This finding suggests that the plasma energy, which may have been amplified by gNPs, could induce severe stress to the S. mutans cell walls. The most likely mechanisms of the synergistic effect of the microwave plasma and gNPs might be enhanced electric field and local heating near the gNPs. High electric conductivity and the nano-size geometry of the gNPs lead to electric field concentration on gNPs [21-23]. The enhanced electric field near the gNPs might attract or repel charged particles. This could cause ion bombardment from the plasma [24] and

Low-temperature plasma radiofrequency ablation (coblation) is a relatively novel technique with promising applications in neuropathic pain. It has been suggested effective for the treatment of phantom limb pain, 13 lumbar discogenic pain, 14 and thoracic neuropathic pain, 15 among others. Nevertheless, the use of coblation for TN is limited by the plasma knife head that cannot be located in the Gasserian ganglion. In the present study, a nerve stimula- tor was modi fi ed and connected to a plasma knife head to solve this problem of location.

In this study, we investigate and compare the physicochemical and morphological properties, as well as the sorption potential, of a natural Bulgarian zeolite (NBZ) and a low-temperature plasma- modified zeolite (LTPMZ). The NBZ was treated with low-temperature arc plasma. The evolution of the modifications was followed using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectrophotometric (UV-VIS), physicochemical and sorption studies. Digital microscope analyses proved that the crystallinity, sheet structure and textural properties of the natural material were not significantly affected by the plasma treatment. The comparative analyses of the obtained FTIR spectra showed that the plasma treatment caused the breakdown of siloxane groups at the clay surface and induced the formation of new silanol groups at the clay edges. According to the UV/VIS and FTIR studies of Rhodamine 6G (Rh6G) sorption, the LTPMZ displayed a higher affinity to the cationic dye compared to the NBZ. This study demonstrates that low-temperature plasma treatments could be used to activate zeolites for environmental applications.

A total of 111 CSA patients (>60 years old) with cognitive dysfunction were received and treat- ed with low-temperature plasma ablation of nucleus pulposus in the Orthopedics Depar- tment of Shanghai Fengxian District Central Hospital from January 2012 to November 2014. They were followed up for 3 years after treatment. CSA was diagnosed according to the diagnostic criteria in The Second Session of the National Symposium on Cervical Spondylosis: (1) patients with the history of chronic strain, which is commonly observed in the working with head lowering or long-term bending over a desk; (2) patients with neck soreness and ten- sion of neck muscle with tenderness by press- ing, which is mainly observed in the middle and upper part of the neck; (3) patients with chronic or paroxysmal headache, dizziness, blurred vision, swallowing difficulties; (4) patients with limited neck movement and positive results of revolve-cervix test.

The plasma is a kind of material form consisting of free electrons and charged ions. It is often regarded as the fourth state of matter, after solid, liquid and gas. There are three types of plasma: high temperature plasma, hot plasma and cold plasma [1]. Low temperature plasma is mainly used for the plasma-assisted film deposition, plasma polymerization, material surface modification, biological sample treatment, nano-material preparation, plasma chemistry and electron beam, the generation of particle beam and laser beam [2]. With the development of the research on plasma and the related processing technologies, the precision improvement of industrial processing equipment and the development of power electronics technology, various testing and control devices have been applied in this field, such as mechanical pressure gauges, manual control valves and off-line plasma parameter diagnostic equipment, which makes the parameters of low temperature plasma can be controlled. Therefore, the treatment process effect of plasma is as good as that of traditional process, and even surpass that of traditional methods in some fields. The advantages of low-temperature plasma such as non-waste, non-pollution and low cost are gradually highlighted.

In this paper, it studied parameters of low-temperature plasma (LTP) used in systems for cleaning waste gas. LTP created by positive nanosecond corona discharges, generated by high voltage pulses with a rise time of 50 ns, duration up to 400 ns, an amplitude up to 90 kV and pulses repeti- tion 50 - 1000 Hz in coaxial electrode system with gap space 3 - 10 cm through which moving air with linear velocity v = 0.01 to 10 m/s. It was found that parameters of LTP depended on the flow velocity. The results of probe measurements of streamers current showed that on the above gaps and pulse parameters took place streamer breakdown with average field strength less than 10 kV/cm. This limits the energy input into the gas via a streamer corona and, accordingly, produc- tivity of cleaning plants.

Lung cancer is the leading cause of cancer-related deaths among men worldwide. Currently, treatment of lung cancer includes surgery, chemotherapy, targeted ther- apy, radiation, radiofrequency ablation, or a combination of these therapies. 1,2 However, treatment outcomes are generally poor. Therefore, to explore effective therapeutic strategies for lung cancer is essential. Low-temperature plasma (LTP) is a useful tool with several applications in the biomedical fi eld, such as wound healing, 3 teeth treatment, 4 blood coagulation 5 and tumour therapy. Recent studies showed that LTP is a promising alternative treatment for cancer.

MRI is highly sensitive and is the dominant imaging modality used for focal treatment [85, 86]. To undertake stan- dard MRI, endorectal and pelvic phase-arrayed coils are used in conjunction to improve positioning of the prostate and to receive MR signals, respectively, resulting in clearer images with optimal signal-to-noise ratio [79]. he prostate zones are clearly visualized using MRI [87]. However, standard MRI is not accurate enough to determine precise location and diagnosis, where multiparametric MRI is required [88]. his includes difusion-weighted imaging (DWI-MRI) that mea- sures water difusivity, dynamic contrast enhanced (DCE- MRI), making use of a contrast agent, and proton magnetic resonance spectroscopic imaging (H MRSI) that measures metabolites (citrate, choline, creatine, and polyamines), the ratios of which change between normal and cancerous prostate [89]. he technology to allow real-time MRI-guided biopsy has also advanced, and it is conceivable that this would be the ultimate method used when administering any focal therapy, including low temperature plasma-based treatment [88, 90–92].

The XRD spectra of the untreated and plasma-treated PCL scaffolds after mineralisation are shown in Figure 4. The deposited coating is composed of the vaterite and calcite phases. The diffractograms show three diffraction peaks assigned to the (112), (114), and (300) planes of the vaterite phase (ICDD card no. 86-0174) and one peak assigned to the (104) plane of the calcite phase resolved at 29° (ICDD card no. 86-0174). The presence of calcite is established in all the studied samples. The observed XRD peaks are quite broad, which leads to the conclusion that the CaCO 3 coatings

Si:H growth, there is a distribution of slightly different bond lengths and angles that result in a distribution of weak and strong Si-Si bonds. The radicals will likely be able to insert into only a fraction of the surface Si-Si bonds. Although the distribution of weak and strong bonds is expected to change with temperature, for simplicity we assume that only a small constant fraction (f = 0.1) of the surface Si-Si bonds have strain energy above a threshold value that facilitates the insertion reactions. The choice of this value is somewhat arbitrary but the trends predicted by our model do not change significantly by the value chosen. This effectively renders ~90% of the surface Si-Si bonds to be stable to surface reaction, similar to “network” Si-Si bonds. This model therefore provides a means for silicon network formation not present in most other models. That is, Si-Si bond formation can proceed between two neighboring silicon hydrides, and ~90% of these bonds will not be affected by further surface reaction and will remain in the film. Finally, the surface hydrides may also recombine dissociatively at elevated temperatures resulting in two adjacent dangling bonds (for example, if the Si atoms are too far apart to form a Si-Si bond) as shown as Reaction M. The energetics of this reaction have been studied extensively at high temperatures and the barriers are reported to be between 1.8- 2.5 eV [36] and therefore we assign a value of 1.9eV to the barrier for this reaction.

All the experiments were carried out at atmospheric pressure and no external heating was used to heat the reactor. The first set of experiments were conducted using a corona discharge plasma at various feed flow rates and a fixed methane to oxygen ratio of 4:1 (volume basis). To enhance the stability of gas discharge, the feed was diluted with argon (60% of volume). The effect of the input power and the total feed flow rates on methane and oxygen conversion is illustrated in Figure 4. The conversions of methane and oxygen are increased at higher levels of input power to the reactor. Increasing the input power to the reactor gives rise to an enhancement in the intensity of the internal electric field developed across the discharge gap; consequently, the density of high energy electrons in the generated gas discharge plasma will also increase. The high energy electrons upon interactions with methane and oxygen molecules will increase the probability of breaking the bonds between hydrogen and carbon in methane molecules and hence the methane conversion increases at higher levels of input power supplied to the reactor. Figure 4 also confirms that increasing the total flow rates to the reactor reduces the conversion of both methane and oxygen. It can be inferred that the energy levels of the electrons produced in gas discharge plasma are not equal but obey the Boltzmann’s energy distribution function; hence only a limited number of electrons which have sufficiently high energy can participate in the formation of active species on collision with methane or oxygen molecules. When the residence time of the reaction decreases, the probability that each methane or oxygen molecule will successfully interact with any of the sufficiently high energy electrons is decreased, and thereby reducing the rate of methane and oxygen conversion.

A low temperature plasma carburizing process can produce an expanded-austenite layer (generally called the S phase), which has high hardness and corrosion resistance at the surface of austenitic stainless steels. We have investigated S phase formation behaviors by using a combined process of active screen and DC plasma carburizing for austenitic stainless steels such as JIS SUS304 and 316 with the aim of de- veloping a highly effective and efficient production technique. The influence of carburizing parameters (processing temperature, time, gas at- mosphere, etc.) on the formation of the S phase was studied in terms of thickness, hardness, carbon concentration, lattice constant, and residu- al stress. The mechanical properties and corrosion resistances of the obtained S phases were also evaluated by using a ball-on-disk test and a salt spray test (SST). The results show that S phases produced efficiently by the combined process under a condition of 733 K and a 10.5 vol% of CH 4 gas ratio have both excellent wear and corrosion resistances.[doi:10.2320/matertrans.H-M2017822]

Abstract. The contact non-equilibrium low-temperature plasma technique is used to synthesize silver nanoparticles (AgNPs) employing trisodium citrate as capping agent. The AgNPs were characterized using UV-Vis spectroscopy, an absorption band at 400-440 nm confirmed nanoparticles formation. The effect of reaction conditions such as the concentration of silver ions, molar ratio Ag/citrate, irradiation time on the synthesis of AgNPs was studied. Characterization of AgNPs was carried out using scanning electron microscopy, X-ray diffraction and zeta potential analysis. The average size of formed silver particles was below 100 nm. XRD analysis revealed that the particles were face-centred cubic. The synthesized silver nanoparticles had significant antibacterial activity on two strains of Gram bacteria.

This article focuses on the study of the defined values of tensile strain and the effect of low temperature plasma adhesion selected coatings on steel samples using a tensile testing flat test bars. Samples were made by machining and welding technologies. The flat test bars were tested by pulling on a test rig UPC 1200. Part of the samples was treated on the surface prior to coating by a tensile test, second base coat and with a final coat con- tinuous multi plasma system. The selected test samples were determined from the tensile test of the material characteristics apparent from the tensile diagrams. The examined samples were fitted top and base coat. Another group was the KTL basis. The presented graphs show the depen- dence of the strength on elongation of a sample according to DIN EN ISO 6892-2. The samples were then examined under a stereo microscope SCHUT brand, type SSM-E in the laboratory to conduct coating on a steel sheet at the moment of total violation sectional samples. The base layer, in which the temperature ranges from 160˚C - 180˚C, was applied by electrophoresis method.

Glow discharge is a form of electric discharge that occurs at a low pressure [3]. In an electric field, electrons are accel- erated easily but other heavy particles (ions and neutrals) are not. Under low-pressure conditions, collisions between elec- trons and other particles do not occur frequently, so the sys- tem does not reach thermal equilibrium. This means that the electron temperature is high, whereas the gas temperature remains low. Therefore, glow-discharge plasma is referred to as a low-temperature plasma, in which the pyrolysis of lignocellulosics does not occur. A typical application of the glow-discharge plasma is the surface modification of mate- rials, such as hydrophilization and hydrophobization [10]. Surface modifications of cellulosic fibers in glow-discharge plasma have also been reported [11, 12], but limited studies exist on lignocellulosics decomposition. Hence, this study deals with glow-discharge plasma to elucidate the decompo- sition behaviors of cellulose without the effect of pyrolysis reactions.

Low temperature screen plasma technology, a high plasma density, through using a low energy supply, shows excellent effects on a low alloy chromium-molybdenum steel for plastic molds be- cause it does not show a compound layer and a high surface hardness without a deterioration in matrix hardness. For interest about hardening depth, both the screen plasma nitriding and plasma nitro-carburizing processes were tested including nitrogen, hydrogen and a methane mixed gas environmental at 653 K, 713 K. The optical emission spectroscopy (OES) has been analyzed during screen plasma nitriding (SPN) and a nitro-carburizing process (SPNC) was proceeded at 713 K and the same pressure. I find it difficult to dissociate nitrogen molecules perfectly with neutral nitro- gen atoms via the DC-plasma nitriding process. Therefore, the SPN and SPNC process have shown a high density of plasma species even though low temperature plasma conditions have a high peak intensity of H β and H γ in the results of the analysis by OES. The hardness value was measured with

plasma. Here, in particular, it was examined how diamond particles grew on a nickel substrate under an influence of Cu vapor that was supplied from a heated Cu wire. Here, the plasma was generated by a hollow-magnetron-type (HMT) RF plasma source at the frequency of 13.56 MHz. Total pressure was kept at 100 mTorr. Diamond particles grew besides Ni and Cu particles. From Raman spectrum the substrate surface was covered with thin graphite film deposited as a background layer. It was shown that diamond could grow in a self-organized manner even when the other atomic gas species such as Ni and Cu were contained in the gas at the same time during the growth process.

As part of an experimental polymorph screen on adenine, (I) was obtained from a 0.3 M aqueous solution of (I), to which approxi- mately 0.15 g of adenine was added, and which was stirred on a hotplate at 303 K for 3 d. This solution was filtered, then evaporated at room temperature (10 ml solution, in 75 25 mm vessels) in an attempt to crystallize adenine, as it has been found that the solubility of purine and pyrimidine bases increases in aqueous amide solutions (Herskovits & Bowen, 1974). Colourless block-like crystals of (I) were formed after a number of days.

tric film deposition. The initial oxidation kinetics and chemi- cal composition of thin oxide are determined from analysis of on-line AES features associated with Ga, N, and O. The plasma-assisted oxidation process is self-limiting with power-law kinetics similar to those for the plasma-assisted oxidation of Si and SiC. Oxidation using O 2 / He plasma