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Sub-micron-sized almost perfect spherical catalysts, FeOx/ZrO2, were prepared by solvothermal and impregnation methods, which were subjected to thermal CVD using C2H2 gas leading to “CNT-hair”.

Purpose As the incidence of oral cancers is on the rise, we aimed to evaluate the usefulness of the prognostic nutritional index (PNI) as a predictor of survival in patients with terminal oral cancer. Methods We evaluated the association between laboratory and PNI values and survival days in 33 patients who died of oral cancer between 2004 and 2019 ,excluding 4 patients who underwent gastric banding out of 39with gastric banding. The observation period was from the date of palliative care recommendation to the date of death. Results A significant difference was observed between the PNI values recorded 3 months before death and those recorded 1 month before death (37.99 ± 6.50 vs 28.86 ± 6.01; PConclusion This study revealed that PNI values decreased toward the end of life and correlated with survival (days), independent of patient characteristics. These findings suggest that the PNI may be useful in the prognostication of end-stage oral cancer.

Background A better understanding of the risk factors for postoperative nausea and vomiting (PONV) could improve patient outcomes. This study aimed to analyze the risk factors for PONV and its onset after third molar impaction surgery, and to demonstrate the importance of controlling anesthesia-related factors regardless of patient-specific factors. Methods We included patients who reported nausea and vomiting within 12 h of extubation. Patients with incomplete data, those who could not communicate, and those with gastrointestinal disorders were excluded. We evaluated patient-specific risk factors, and the use of volatile anesthetics and intraoperative fentanyl anesthetic-related factors. Multiple logistic regression analysis was performed taking patient background factors into account. Results In total, 182 patients who underwent disimpaction of the third molar under general anesthesia between January 2017 and December 2018 at Nagoya Ekisaikai Hospital, were included. Approximately 12.6% (n = 23) patients experienced PONV, with no significant difference in terms of sex, smoking status, age, and body mass index compared to patients without PONV. Multiple logistic regression analysis revealed no interaction between fentanyl and volatile anesthetics. The major risk factor for PONV was the use of volatile anesthetics. Patients in whom anesthesia was maintained by volatile anesthetics were 13.35 times more likely to have PONV than those in whom total intravenous anesthesia was induced (P Conclusion Maintenance of anesthesia with volatile anesthetics is a risk factor for PONV.

To investigate the prognostic impact of preoperative Geriatric Nutritional Risk Index (GNRI) values in older adults undergoing radical surgery for oral squamous cell carcinoma (OSCC).This retrospective study included 61 patients ≥65 years old with OSCC (43 men, 18 women; age: 72.1 ± 5.4 years) who underwent radical surgery between 2013 and 2020. Factors influencing overall survival (OS) and disease-free survival (DFS) were examined.Receiver operating characteristic curve analysis indicated that the optimal GNRI value for classifying patients into low-GNRI (93.7; OS: n = 19 [31.1%], DFS: n = 42 [68.9%]) and high-GNRI groups (≥93.7; OS, n = 19 [31.1%]; DFS, n = 42 [68.9%]) was 93.7. OS and DFS rates were significantly lower in the low-GNRI group than in the high-GNRI group. Univariate analysis indicated that alcohol use, preoperative serum C-reactive protein level, lymphatic invasion, postoperative treatment, and GNRI were significantly correlated with OS, while lymphatic invasion, postoperative treatment, and GNRI were significantly correlated with DFS. In multivariate analysis, only GNRI was significantly correlated with OS. DFS and postoperative treatment were independent predictors of DFS.Preoperative GNRI may be a significant prognostic factor in older adults with OSCC. GNRI assessment and nutritional intervention may improve prognosis in patients at high nutritional risk.

Current methods used to treat non-muscle invasive bladder cancer are inadequate due to a high recurrence rate after surgery and occurrence of adverse events such as interstitial pneumonia following intravesical instillation therapy. Low-temperature plasma is a new form of physical therapy that provides a rich source of reactive oxygen species (ROS). Oxidative solutions, created by pre-treatment of aqueous media with plasma before application to target cells, lead to the destruction of cancer cells through oxidative stress pathways. This study focuses on the effects of plasma activated media (PAM) in bladder cancer cells. PAM treatment increases up regulation of p21 and down regulation of Cyclin D and CdK4 leading to cell cycle arrest, and concomitantly depolarises the mitochondrial membrane leading to increased mitochondrial ROS production. Cell cycle arrest and increased mitochondrial ROS production induce apoptosis in bladder cancer cells in vitro and in a bladder cancer tumour in vivo via the pro-apoptotic caspase 3/cytochrome c pathway. These observations highlight the potential of plasma activated solutions as a new adjuvant therapy in the clinical treatment of bladder cancer.

Recently, marine resources have been attracting much attention owing to their growing role in sustainable development. Growing interest in the exploration of marine resources and numerous studies on ecology and biochemistry has made the high-precision analysis of sea water necessary. In this paper, the possibility of using the atomic emission spectroscopy of microarc discharges generated in sea water for on-site contaminants detection and elemental composition analysis has been studied. We analyzed the discharge process and optical emission spectra from microarc discharges in three types of liquid, namely, artificial sea water composed of ten main components, reference solutions containing a single component each, and naturally sampled deep sea water. Microarc discharges were generated under low breakdown voltages using a compact experimental setup with a needle-to-plate electrode system immersed in each liquid in a quartz cuvette. In the spectra, the emission peaks of the main components of sea water and contaminants from the electrodes were detected, and reference solutions were used for the identification of unassigned peaks. To study the effect of electrode materials on the optical emission spectra and plasma parameters, three types of needle electrodes were used. The effect of the experimental conditions on the measured optical emission spectra was studied, and the applicability of proposed method for on-site detection of metals and elemental composition analysis was confirmed.

A pulsed-dc discharge method for plasma chemical vapor deposition (CVD) was developed using a constructed versatile pulsed-dc generator and a vacuum discharge chamber. Argon (Ar) gas discharge experiments were performed under a variety of discharge conditions, and plasma conditions were evaluated using optical emission spectroscopy. The developed system can perform glow discharge by employing nearly rectangular, unipolar, and high-voltage negative pulses with a wide variation of voltage amplitudes and a set discharge current, pulse repetition rate, and duty cycle. Plasma conditions could also be tuned by varying the pulse parameters. A preliminary test of the deposition of diamond-like carbon (DLC) films on silicon (Si) substrates and ultrathin pyrolytic carbon (PyC) films on nanothickness metal-catalyzed glass substrates was performed with acetylene (C 2 H 2 ) by selecting some typical deposition conditions based on the gas discharge experiments. The deposited films were characterized via Raman spectroscopy. The characteristic properties of DLC and PyC films were achieved. The DLC films demonstrated conventional hard insulating properties while the ultrathin PyC films exhibited conductive and semitransparent properties. These results revealed that the developed pulsed-dc discharge system for plasma CVD is applicable for the synthesis of insulating hard as well as soft conducting carbon thin films.

Systemic inflammatory responses and nutritional status are useful prognostic factors in gastric cancer patients. Since oral hypofunction causes undernutrition, we cross-sectionally investigated whether nutritional biomarkers were affected by the occlusal supporting zone status.In 114 gastric cancer patients, the gastric cancer stage, body mass index, albumin levels, total lymphocyte counts, cholesterol levels, C-reactive protein levels, and 4 nutritional biomarkers - the Glasgow prognostic score (GPS), neutrophil-lymphocyte ratio, prognostic nutrition index (PNI), and controlling nutritional status (CONUT) - were evaluated. Oral conditions were assessed by determining the number of remaining teeth. The occlusal supporting status was based on the Eichner classification. Patients were assigned into 3 groups per their occlusal status, and mean values were compared using the Kruskal-Wallis test. The mean age and body mass index were 72.2 ± 8.5 (50-89) years and 22.0 ± 3.6 (14.8-33.4), respectively. There were 42, 39, 23, and 10 patients in stages I, II, III, and IV, respectively. The mean number of remaining teeth was 18.1 ± 9.5. According to the Eichner classification, there were 45, 42, and 27 patients in groups A, B, and C, respectively. The GPS and neutrophil-lymphocyte ratio values and CONUT frequencies between groups A and C were significantly different (P = .033, P = .00097, P = .04, respectively; Mann-Whitney U test). PNI values were lower in group C with poor occlusal support zones than in group A with stable occlusal support zones.Occlusal supporting zone reductions were undernutrition associated. Eichner Class C patients with few occlusal supporting zones had poor GPS, PNI, and CONUT values and were undernourished.

Background The systemic inflammatory response and nutritional status of patients with malignant tumors are related to postoperative results. We examined the usefulness of the prognostic nutritional index (PNI) as a prognostic tool in patients with oral squamous cell carcinoma who underwent radical surgery. Methods From 2008 to 2019, 102 patients (73 males, 29 females; age, 65.6 ± 9.8 years) who visited our hospital and underwent surgical therapy were included in this study. The endpoint was the total survival period, and the evaluation markers included the lymphocyte count and albumin level in peripheral blood obtained 4 weeks preoperatively, age, sex, alcohol consumption, smoking history, site of the tumor, pathological stage, and surgery status. The PNI was calculated using serum albumin levels and the peripheral blood lymphocyte count. The relationship between the PNI and patient characteristics were analyzed using Fisher's exact test. The Kaplan–Meier method was used to evaluate the survival rate. The survival periods were compared using the log-rank method. We evaluated the prognostic factors for overall survival (OS) and disease-free survival (DFS) in a logistic regression model. Results The tumor sites included the maxilla (n = 12), buccal mucosa (n = 11), mandible (n = 17), floor of the mouth (n = 9), and tongue (n = 53). The number of patients with stage I, II, III, and IV oral cancers was 28 (27.5%), 34 (27.5%), 26 (33.3%), and 14 (13.7%), respectively. During the observation period, 21 patients died of head and neck cancer. The optimal cut-off PNI value was 42.9, according to the receiver operating characteristic analysis. The proportion of patients with a short OS was lower in those with PNI higher than 42.9, and the 5-year OS in patients with PNI higher and lower than the cut-off value was 62.3% and 86.0%, respectively (P = 0.0105). Conclusions The OS of patients with PNI

The Taguchi method of design of experiments was utilized to tune the optical properties of a carbon nanotube (CNT) forest by decreasing the total ultraviolet-visible (UV-Vis) reflectance. The CNT growth parameters included the acetylene flow rate, the thickness of the Fe catalyst film, substrate polarization potential (bias) during sputtering of the AlOx buffer layer, and acetylene-to-hydrogen gas flow ratio. A plot of the signal-to-noise (SN) ratio showed that the buffer-layer bias and catalyst thickness had the highest impact on the final results of the total optical reflectance. A verification experiment was conducted based on the optimized values of the growth parameters, and it yielded a 45% decrease in the UV-Vis reflectance to the lowest value (0.077% at λ = 750 nm) ever reported for a thin CNT forest film with relatively low height (∼20 μm). In addition, the structural parameters of the CNT forest were studied. The effects of the CNT structure (single-walled CNTs (SWCNTs), double-walled CNTs (DWCNTs), and multi-walled CNTs (MWCNTs)), filling factor (density), and alignment of CNTs on the total optical reflectance were investigated. The density and alignment of CNTs showed the highest impact, while the individual CNT structure exhibited a negligibly small effect on the low total optical reflectance.

In this paper, the optical properties of a frost column-like carbon nanotube (CNT) forest, a hybrid structure of carbon film and a CNT forest, in which carbon films are supported by low-density, vertically-aligned CNT forests, are reported for the first time. The frost column-like CNT forest exhibits a significant interference reflectance, which is not typically observed in conventional CNT forests. Oscillating spectra in the visible (VIS) reflectance were analyzed by simple optical interference between the substrate and carbon films. Fishnet type metamaterial patterns of catalyst films were successfully fabricated by focused ion beam (FIB) pattern processing, followed by CNT growth using a thermal catalytic chemical vapor deposition (CVD) method. Optical properties of fishnet-type frost column-like CNT forest were also investigated. We also found that within the infrared region, optical absorption increased with fishnet type metamaterial CNT, frost column-like CNT forest, compared with non-patterned one. These results suggested that a metamaterial effect of fishnet patterns was observed.

Pulsed DC plasma chemical vapour deposition (CVD) system with a compact vacuum chamber has been developed using a simple configured pulsed DC power supply. Pulsed DC discharge was examined with variation of operation parameters as well as source gas materials. Diamond like carbon (DLC) films were deposited on silicon (Si) substrates from acetylene (C2H2) or carbon-monoxide (CO) at two distinct temperatures. The fabricated films were characterized by Raman spectroscopy, FTIR spectroscopy, and scanning electron microscopy (SEM). The results reveal that the films prepared from CO gas exhibited soft conductive DLCs with a large number of graphite like structures whereas mostly insulating hydrogenated amorphous carbon DLCs were obtained from C2H2 gas. The deposition rate from CO was lower than from C2H2 due to etching by oxygen produced from the source gas. As the substrate temperature increased, progressive graphitization was incorporated to the films deposited from both gases. By using the pulsed DC plasma CVD system, the energy efficiency for CVD as the ratio of growth volume to energy consumption was dramatically improved with some distinctive differences in film properties as compared to our previous RF plasma CVD. The results showed many advantageous features of pulsed DC plasma CVD for replacing conventional RF plasma CVD.

The incidence of accidental ingestion and aspiration of foreign body (FB) is likely to occur. Many FBs are discharged spontaneously, but many dental FBs are often sharp and may remain in the pharynx, esophagus, and stomach, causing serious complications such as hemorrhage, asphyxia, perforation of the digestive tract, mediastinal emphysema, peritonitis, and ileus. We aimed to examine which type of dental foreign bodies can be removed by endoscope.In this study, we enrolled 32 patients who were evaluated at the Emergency and Critical Center between January 2014 and December 2019 and who accidentally ingested or aspirated dental FBs. Medical records were reviewed to determine the patients' sex, age, medical history, time from accidental ingestion of a FB to consultation, cause, location, occurrence status, nature of the FB, location of retained FB, treatment, complications, and outcome.We enrolled 32 patients (14 men, 18 women), with a mean age of 74.5 ± 12.8 years. Accidental ingestion at treatment was common. The most frequent site where the FB was retained was upper gastrointestinal tract (26 cases, 81.3%). In this study, endoscopic removal was indicated for dentures under the size of 43.3 mm, for dental FB (except dentures) more than 13.6 mm. In dentures, between the number of missing teeth, clasp, type, and endoscopic removal was not statistically significant.Dentures under the size of 43.3 mm was likely to be removed by endoscope. Dental FB (except dentures) more than the size of 13.6 mm was likely to be removed by endoscope. There were no indications for endoscopic removal except for size.

In oral cancer surgery, the decision to perform a tracheotomy is often determined by the surgeon. In this study, we investigated the competency of clinical scoring systems in identifying patients who require tracheotomy and examined the degree of agreement between the surgeon's decision and the indications of various scoring systems. We identified 110 patients who were surgically treated for oral cancer. Of these, 67 patients (44 men and 23 women) who underwent resection and reconstruction were retrospectively analyzed. To derive the score, we evaluated the endpoint of the airway management score using clinical records and images. We divided the patients into two groups based on the Cameron and Gupta scores (tracheotomy and no-tracheotomy groups) and evaluated the degree of agreement with the surgeon's decision by calculating the κ coefficient. The κ coefficients of the Gupta and Cameron scores were 0.61 (95% confidence interval [CI]: 0.40–0.82) and 0.60 (95% CI: 0.38–0.82), respectively. The clinical evaluation of the κ coefficient indicated that the Cameron and Gupta scores agreed fairly with the surgeon's decision. In this study, the Cameron and Gupta scores fairly agreed with the decision of experienced surgeons and were confirmed as acceptable guides for making clinical judgments.

Electrically anisotropic one-dimensional materials, like carbon nanotubes (CNTs), have high potential to become substitutes to conventional metamaterials made of metals, and to overcome their limitations. The exceptional properties of CNT metamaterials are to be expected, mainly due to the anisotropic optical and electrical properties of the CNTs, which behave like one-dimensional nanorod antennas in the electromagnetic radiation. In this work, the infrared properties of novel CNT forest metamaterials, prepared on the patterned catalyst film are presented. The influence of the inner structure of CNT forest metamaterials, such as an orientation (horizontal and vertical), density and alignment of CNTs within the forest, are studied for the first time, in the non-polarized infrared light. The investigation of the phenomena responsible for changes of the total IR reflectance and transmittance of the patterned CNTs was carried out and showed the decrease of the total reflectance and transmittance with the improvement of the density and the alignment. Furthermore, the simulation of the anisotropic behavior of patterned CNT forest, and SRR orientation towards the electric field E were investigated for the first time and showed major changes in the transmittance, with the lowest values of transmittance achieved for y-axis anisotropy and perpendicular orientation of the SRR to the E field. Simulation results showed for the first time, that the effect of anisotropic structure can be stronger than the effect of the SRR orientation.

Anisotropic materials, like carbon nanotubes (CNTs), are the perfect substitutes to overcome the limitations of conventional metamaterials; however, the successful fabrication of CNT forest metamaterial structures is still very challenging. In this study, a new method utilizing a focused ion beam (FIB) with additional secondary etching is presented, which can obtain uniform and fine patterning of CNT forest nanostructures for metamaterials and ranging in sizes from hundreds of nanometers to several micrometers. The influence of the FIB processing parameters on the morphology of the catalyst surface and the growth of the CNT forest was investigated, including the removal of redeposited material, decreasing the average surface roughness (from 0.45 to 0.15 nm), and a decrease in the thickness of the Fe catalyst. The results showed that the combination of FIB patterning and secondary etching enabled the growth of highly aligned, high-density CNT forest metamaterials. The improvement in the quality of single-walled CNTs (SWNTs), defined by the very high G/D peak ratio intensity of 10.47, demonstrated successful fine patterning of CNT forest for the first time. With a FIB patterning depth of 10 nm and a secondary etching of 0.5 nm, a minimum size of 150 nm of CNT forest metamaterials was achieved. The development of the FIB secondary etching method enabled for the first time, the fabrication of SWNT forest metamaterials for the optical and infrared regime, for future applications, e.g., in superlenses, antennas, or thermal metamaterials. Electronic supplementary material The online version of this article (doi:10.1007/s40820-017-0145-5) contains supplementary material, which is available to authorized users.

Microplasma discharge in sea water was investigated using a needle-to-plane electrode system with various types of needle insulation. A platinum plane electrode and a palladium needle electrode were placed with a gap of 20 $\mu \text{m}$ in the artificial sea water. A pulse current source, consisting of a MOSFET switch, a capacitance, and inductance, was used. The sea water between the electrodes performed as resistance for the current source circuit. Using the microgap configuration, microplasma discharges were reproducibly ignited under low breakdown voltages in the highly conductive sea water. In order to significantly diminish the current dispersing into the surrounding water, the needle electrode was insulated, enabling more accurate investigation of the preheating and bubble formation processes before the microplasma discharge. It was established that the microplasma discharge was ignited after formation of the bubble of size, sufficient to cover entire discharge gap between the electrodes. Influence of the needle electrode insulation on microplasma parameters was investigated.

In this work, micro-arc discharge is investigated using a needle-to-plane electrode system placed with a micro-gap in highly conductive artificial seawater. A major problem with microarc discharge is the erosion of electrodes caused by the high current of the arc, however, it was found that erosion of the needle electrode did not have any effect on the discharge process in the case of precise control of the discharge gap. A simple mathematical model was developed for a more detailed study of the preheating phase of the discharge. The modeling showed good agreement with the experimental results and confirmed that the needle electrode could be reused to generate reproducible micro-arc discharges even after the erosion caused by the arc. Moreover, it was found that, in certain conditions, the preheating phase could be simulated using a simple inductor-capacitor-resistor (LCR) oscillator model with a resistor instead of electrodes immersed in the liquid. It was confirmed that the shape of the needle electrode&rsquo, s tip did not affect the measurement of optical emission spectra in the case of precise focusing, which could be used in the development of compact analytical tools for on-site analysis of deep-sea water using atomic emission spectroscopy.

A growth of Carbon Nanotubes (CNTs) suffers many difficulties in finding optimum growth parameters, reproducibility and mass-production, related to the large number of parameters influencing synthesis process. Choosing the proper parameters can be a time consuming process, and still may not give the optimal growth values. One of the possible solutions to decrease the number of the experiments, is to apply optimization methods to the design of the experiment parameter matrix. In this work, Taguchi method of designing experiments is applied to optimize the formation of iron catalyst during annealing process by analyzing average roughness and size of particles. The annealing parameters were: annealing time (t AN ), hydrogen flow rate (f H2 ), temperature (T AN ) and argon flow rate (f Ar ). Plots of signal-to-noise ratios showed that temperature and annealing time have the highest impact on final results of experiment. For more detailed study of the influence of parameters, the interaction plots of tested parameters were analyzed. For the final evaluation, CNT forests were grown on silicon substrates with AlO X /Fe catalyst by thermal chemical vapor deposition method. Based on obtained results, the average diameter of CNTs was decreased by 67% and reduced from 9.1 nm (multi-walled CNTs) to 3.0 nm (single-walled CNTs).

In this work, a fractal analysis of a morphology of carbon nanotube (CNT) forest was conducted. A self-similarity between the formation of catalyst nanoparticles, low and high-density CNT forest growth, and Raman mapping was investigated, for a catalyst thickness of 0.8, 1.0, and 1.2 nm. To explain reasons behind fluctuations of the CNT forest structure, a fractal dimension (Df) and lacunarity (Λ) were calculated, using a box-counting method. During the fractality analysis of catalyst particles, the highest Df was obtained for the 0.8-nm-thick film (Df = 1.91), while the lowest one was noted for the Fe catalyst thickness of 1.2 nm (Df = 1.72). The progressive increase of the catalyst thickness affected the dewetting, Ostwald ripening and diffusion processes, affecting the catalyst size distribution and arrangement. The same thickness variation led to a similar decreasing trend of Df changes, which was observed in the planar and linear analysis of the distribution of CNTs and in the IG/ID ratio distribution in Raman mapping, confirming the complexity and the self-organizing properties of CNT forest. The self-similarity and scaling of properties of self-organized CNT forest structure were proved by the analysis of fractal dimension and lacunarity analysis and revealed different stages of the catalyst annealing.

In this work, shape-dependent mid-infrared properties of novel split ring resonator (SRR) metamaterials composed of single-walled carbon nanotube (CNT) forest are investigated. The introduction of the gap and dip shape to the closed ring geometry reduced the total reflectance by 15%, due to the generation of circular currents and LC resonances in SRRs. The increase of the SRR height reduced the total IR reflectance by 25%. Unique one-dimensional anisotropic electric and photonic properties of CNTs, combined with an artificial refractive index induced in SRR circuits, will stimulate the development of new optoelectronics applications.

Chemical components induced in water by irradiation to atmospheric pressure He plasma jet in ambient air has been investigated using UV absorption spectroscopy. There appears a characteristic absorbance peak in UV range for deionized water after irradiation to plasma jet. The UV absorbance peak can be well deconvoluted to 4 characteristic components assigned as O 2 , NO 2 -, NO 3 -, and H 2 O 2 , and from the analysis, the absolute concentration can be determined.

Plasma-activated water ( PAW) is receiving much attention in biomedical applications because of its reported potent bactericidal properties. Reactive oxygen and nitrogen species (RONS) that are generated in water upon plasma exposure are thought to be the key components in PAW that destroy bacterial and cancer cells. In addition to developing applications for PAW, it is also necessary to better understand the RONS chemistry in PAW in order to tailor PAW to achieve a specific biological response. With this in mind, we previously developed a UV-vis spectroscopy method using an automated curve fitting routine to quantify the changes in H2O2, NO2 %, NO3 % (the major long-lived RONS in PAW), and O-2 concentrations. A major advantage of UV-vis is that it can take multiple measurements during plasma activation. We used the UV-vis procedure to accurately quantify the changes in the concentrations of these RONS and O-2 in PAW. However, we have not yet provided an in-depth commentary of how we perform the curve fitting procedure or its implications. Therefore, in this study, we provide greater detail of how we use the curve fitting routine to derive the RONS and O-2 concentrations in PAW. PAW was generated by treatment with a helium plasma jet. In addition, we employ UV-vis to study how the plasma jet exposure time and treatment distance affect the RONS chemistry and amount of O-2 dissolved in PAW. We show that the plasma jet exposure time principally affects the total RONS concentration, but not the relative ratios of RONS, whereas the treatment distance affects both the total RONS concentration and the relative RONS concentrations. (C) 2018 The Japan Society of Applied Physics Refereed/Peer-reviewed

A DC micro plasma jet for local micro deposition of a:C-H film in the ambient vacuum of scanning electron microscope (SEM) chamber is proposed. Acetylene (C2H2) gas was locally fed into the chamber through an orifice shaped gas nozzle (OGN) at 6.6 sccm in flow rate by applying 80 kPa-inlet pressure with an additional direct pumping system equipped on the SEM chamber. As a cathode, a cut of n-type silicon (Si) wafer was placed right in front of the OGN at 200 μm gap distance. By applying a positive DC voltage to the OGN, C2H2 plasma was generated locally between the electrodes. During discharge, the voltage increased and the current decreased due to deposition of insulating film on the Si wafer with resulting in automatic termination of discharge at the constant source voltage. A symmetric mountain-shaped a:C-H film of 5 μm height was deposited at the center by operation for 15 s. Films were deposited with variation of gas flow rate, gap distance, voltage and current, and deposition time. The films were directly observed by SEM and analyzed by surface profiler and by Raman spectroscopy.

Long pillar- and tip-shaped nanostructures were formed on diamond-like carbon (DLC) surfaces by RF O 2 plasma etching after deposition of a small amount of metal as a micromask by the dc magnetron sputtering method. Ni, Pt, Fe, Au, and Cu were examined as metal micromasks for deposition on the DLC surface. During the initial etching stage, nanostructures appeared on all of the DLC surfaces with each of the metal micromasks. The initial nanostructures were induced by anisotropic etching with the micromasks of aggregated metal. As the etching duration was increased, the nanostructures grown with Ni and Fe micromasks appeared to be lengthened, while the nanostructures induced by Pt, Au, and Cu completely disappeared. O2 plasma etching for 5 min after deposition of a 0.15-nm thick Ni layer resulted in complete coverage of the DLC surface with fine nanostructures around 30 nm in diameter, 60 nm in height, and an areal number density of 1500 μm -2 . The resultant surface had hydrophilic characteristics with a small water contact angle of 13°.

Using a versatile atmospheric-pressure helium plasma jet, diamond-like carbon (DLC) films were etched in ambient air. We observed that the DLC films are etched at a nominal rate of around 60 nm/min in the treated area (230 μm in diameter) during a 20-min exposure. The etching rate increased after the initial 10-min exposure. During this period, the flat DLC surface was structurally modified to produce carbon nanostructures with a density of ~ 2.4 × 10 11 cm − 2 . With this increase in surface area, the etching rate increased. After 20 min, the DLC film had a circular pattern etched into it down to the substrate where silicon nanostructures were observed with sizes varying from 10 nm to 1 μm. The initial carbon nanostructure formation is believed to involve selective removal of the sp 2 -bonded carbon domains. The carbon etching results from the formation of reactive oxygen species in the plasma.