Argon Treatment Research Articles

Evaluation of the efficacy of therapeutic endoscopy in gastrointestinal bleeding secondary to angiodysplasias.

Gastrointestinal angiodysplasias are defined as vascular dilations that communicate capillaries and veins in the walls of the digestive tract. The clinical presentation of these lesions varies from chronic occult bleeding to severe gastrointestinal hemorrhage. The primary aim of our study was to analyze lesion location, the efficacy of therapeutic endoscopy with argon plasma coagulation, and the factors associated with rebleeding in patients with gastrointestinal angiodysplasias. A retrospective study of 32,042 endoscopies was carried out within the time frame of January 2012 and December 2013 at our hospital center. Gastrointestinal angiodysplasia was the diagnosis in 331 of the endoscopies. The procedures included upper gastrointestinal endoscopy, colonoscopy, sigmoidoscopy, and enteroscopy. The most frequent location of the angiodysplasias was the cecum (49%), followed by the ascending colon (17%) and the sigmoid colon (16%). They were most frequently found in the duodenum (60%) and gastric body (49%) at upper gastrointestinal endoscopy. Therapeutic endoscopy was performed in 163 cases (49.8%) and the most predominant methods were fulguration with argon (90%) and combination treatment (argon plasma coagulation and injection sclerotherapy) (6.7%). The macroscopic rebleeding rate after therapeutic endoscopy was 7.4%. Patients that had rebleeding presented with a lower hemoglobin concentration, higher mean age, and the presence of multiple angiodysplasias at endoscopy (P<.05). Therapeutic endoscopy was performed in 49.8% of the patients with angiodysplasias. The macroscopic rebleeding rate after treatment was 7.4%. There were statistically significant differences in the patients with rebleeding in relation to mean age, hemoglobin values, and the presence of multiple angiodysplasias.

Evaluation of the efficacy of therapeutic endoscopy in gastrointestinal bleeding secondary to angiodysplasias

IntroductionGastrointestinal angiodysplasias are defined as vascular dilations that communicate capillaries and veins in the walls of the digestive tract. The clinical presentation of these lesions varies from chronic occult bleeding to severe gastrointestinal hemorrhage. AimThe primary aim of our study was to analyze lesion location, the efficacy of therapeutic endoscopy with argon plasma coagulation, and the factors associated with rebleeding in patients with gastrointestinal angiodysplasias. Material and methodsA retrospective study of 32,042 endoscopies was carried out within the time frame of January 2012 and December 2013 at our hospital center. Gastrointestinal angiodysplasia was the diagnosis in 331 of the endoscopies. The procedures included upper gastrointestinal endoscopy, colonoscopy, sigmoidoscopy, and enteroscopy. ResultsThe most frequent location of the angiodysplasias was the cecum (49%), followed by the ascending colon (17%) and the sigmoid colon (16%). They were most frequently found in the duodenum (60%) and gastric body (49%) at upper gastrointestinal endoscopy. Therapeutic endoscopy was performed in 163 cases (49.8%) and the most predominant methods were fulguration with argon (90%) and combination treatment (argon plasma coagulation and injection sclerotherapy) (6.7%).The macroscopic rebleeding rate after therapeutic endoscopy was 7.4%.Patients that had rebleeding presented with a lower hemoglobin concentration, higher mean age, and the presence of multiple angiodysplasias at endoscopy (P<.05). ConclusionsTherapeutic endoscopy was performed in 49.8% of the patients with angiodysplasias. The macroscopic rebleeding rate after treatment was 7.4%. There were statistically significant differences in the patients with rebleeding in relation to mean age, hemoglobin values, and the presence of multiple angiodysplasias.

Effect of heat treatment atmosphere on the structure and apatite-inducing ability of Ca, P, Si and Na incorporated microarc oxidation coating on titanium

Amorphous microarc oxidation (MAO) coating containing Ca, P, Si and Na elements on Ti substrate has been heat treated in different atmospheres (air or argon) to adjust the phase composition, surface structure and bioactivity. After heat treatment in air at 800°C for 1h, the coating consists of anatase, rutile and CaTi4(PO4)6, with almost unchanged microporous surface structure. As for the one treated in argon at 800°C for 1h, anatase and rutile are formed on the coating, and the coating surface is covered by flower-like rutile particles. The formation of rutile particles could be attributed to the prior growth of the oxidized β-Ti along the discharge channel caused by the diffusion of incorporated elements. Thanks to the crystallization of TiO2 and the rise of surface roughness, which provides good sites for apatite nucleation, the MAO coated Ti after heat treatment in argon at 800°C exhibits good apatite-inducing ability.

Post-Calcined Carbon Nitride Nanosheets as an Efficient Photocatalyst for Hydrogen Production under Visible Light Irradiation

Hydrogen production via photocatalytic water splitting using sunlight has enormous potential to solve the worldwide energy and environmental crisis. The key challenge in this process is to develop efficient photocatalysts which must satisfy several criteria such as strong sunlight absorption, effective charge separation, and high photochemical stability. Graphitic carbon nitride is one of the best semiconductors for hydrogen evolution because of its conduction band edge, narrow band gap, and high chemical stability. However, it produces a small amount of hydrogen under visible light irradiation due to its small surface area and high recombination rates. In this work, nanosheets of graphitic carbon nitride with carbon vacancies and nanoholes were synthesized by a two-step treatment process (argon treatment followed by air calcination). These post-calcined carbon nitride nanosheets exhibited much higher photocatalytic activity compared to common graphitic carbon nitride. By depositing platinum as a cocataly...

Improvement of the Adhesion Strength of MoSi2-ZrB2 Coating by Optimizing Particle Spraying and Subsequent Heat Treatment

A MoSi2-ZrB2 coating was prepared on SiC-coated C/C composites by supersonic plasma spraying, and the effects of particle diameter and subsequent heat treatment in argon at different temperatures on the adhesion strength were studied. The results show that the MoSi2-ZrB2 coating sprayed with an average powder diameter of 29.2 μm could melt thoroughly and form a dense structure without micro-pore, which results in a relatively good adhesion strength of 11.4 MPa compared with 9.2 and 8.6 MPa of the coatings sprayed with the powder diameter of 58.2 and 35.5 μm. The coating presents a decreasing porosity from 2.2 to 1.5% and an increasing adhesion strength from 11.6 to 16.9 MPa after heat treatment at 800 °C, which is mainly caused by slight sintering of SiO2 and B2O3

High-conductivity SiO2-matrix B-doped Si-NC thin films by following ion-beam treatment

In this work, further ion-beam was performed on SiO2-matrix B-doped Si-NC (SBC) thin films in order to enhance conductivity. The effect of ionbeam type on the electrical properties of SBC thin films was investigated systematically. The results indicated that the conductivities of SBC thin films were significantly improved by both argon and hydrogen ion-beam treatments, and the higher the hydrogen ion ratio, the higher the conductivity of SBC thin films. The conductivity of SBC thin films was increased from 1.82 × 10−6 S/cm to 3.2 × 10−3 S/cm with following hydrogen-ion-beam treatment. The change in conductivity of SBC thin films was most possibly resultant from the ion-beam treatment facilitating the formation of higher superficial order and lower defects. An alternative method was proposed to prepare high-conductivity SBC thin films, which may be applied to other heterogeneous thin films.

Electrochemical Corrosion of HVOF-Sprayed NiCoCrAlY Coatings in CO2-Saturated Brine

The effect of pre-oxidation treatment and surface preparation of optimized NiCoCrAlY coatings deposited by high-velocity oxygen fuel (HVOF) spraying and exposed to a low-temperature corrosive environment is reported herein. Coatings with two surface finish conditions (as-sprayed and ground) were heat treated under two different oxygen partial pressures (air and argon). The electrochemical corrosion behavior was evaluated in CO2-saturated brine via potentiodynamic polarization, polarization resistance, and electrochemical impedance measurements. The results show that the grinding process and pre-oxidation treatment in argon enhanced growth and formation of α-Al2O3 scale. The potentiodynamic polarization results show that both pre-oxidation and surface treatment had a positive influence on the corrosion resistance of the coating. The reduction of the porosity and the formation of a dense, uniform, and adherent oxide scale through pre-oxidation treatment led to an increase of the corrosion resistance due to a decrease in active sites and blocking of diffusion of reactive species into the coating. However, according to the results, complete transformation from metastable alumina phases to α-Al2O3 in addition to formation and growth of dense α-Al2O3 is required to ensure full protection of the coating and base material over long periods.

Oxidation behaviour of the nickel-based superalloy DZ125 hot-dipped with Al coatings doped by Si

A pure Al coating and Al-Si coating were prepared on the surface of the DZ125 superalloy by hot-dipping. The Al-Si coating provides better thermal oxidation resistance than that of the pure Al coating due to the formation of a more compact Al2O3 layer. The microstructure of the Al-Si coating shows a silicon-aluminium-based layer with Ta5Si3 and AlHfSi phase forms after heat treatment in argon at 850°C. This layer is a barrier to the diffusion of oxygen and other metal elements during cyclic oxidation, which has a significant effect on the formation of the compact Al2O3 layer.

The physical mechanism on the threshold voltage temperature stability improvement for GaN HEMTs with pre-fluorination argon treatment

In this paper, a normally-off AlGaN/GaN MIS-HEMT with improved threshold voltage (VTH) thermal stability is reported with investigations on its physical mechanism. The normally-off operation of the device is achieved from novel short argon plasma treatment (APT) prior to the fluorine plasma treatment (FPT) on Al2O3 gate dielectrics. For the MIS-HEMT with FPT only, its VTH drops from 4.2 V at room temperature to 0.5 V at 200 °C. Alternatively, for the device with APT-then-FPT process, its VTH can retain at 2.5 V at 200 °C due to the increased amount of deep-level traps that do not emit electrons at 200 °C. This thermally stable VTH makes this device suitable for high power applications. The depth profile of the F atoms in Al2O3, measured by the secondary ion mass spectroscopy, reveals a significant increase in the F concentration when APT is conducted prior to FPT. The X-ray photoelectron spectroscopy (XPS) analysis on the plasma-treated Al2O3 surfaces observes higher composition of Al-F bonds if APT was applied before FPT. The enhanced breaking of Al-O bonds due to Ar bombardment assisted in the increased incorporation of F radicals at the surface during the subsequent FPT process. The Schrödinger equation of Al2OxFy cells, with the same Al-F compositions as obtained from XPS, was solved by Gaussian 09 molecular simulations to extract electron state distribution as a function of energy. The simulation results show creation of the deeper trap states in the Al2O3 bandgap when APT is used before FPT. Finally, the trap distribution extracted from the simulations is verified by the gate-stress experimental characterization to confirm the physical mechanism described.

Investigation of template effect on zirconium carbide synthesis process in carbothermal method at low temperature condition

The template effect of carbon source precursors on ZrC synthesis at low temperatures were investigated by carbothermal reduction of ZrCl4 using metallic sodium. The polymerization of naphthalene or toluene in the presence of ZrCl4 was directed to formation of two ZrC products including nanorods and nanoparticles. The polymerization behavior of naphthalene or toluene had template effects on ZrC shaping. The ZrC nanorods/nanoparticles were characterized by X-ray and SEM. The results showed that ZrCl4 in both condition was completely transformed to ZrC, after heat treatment in argon at temperatures above 600°C. The SEM study revealed that the nucleation and growth of ZrC nanorods/nanoparticles occurred on the surface of derived polymer from naphthalene/toluene. There was no carbon residue from naphthalene/toluene in the products. The obtained ZrC particles exhibited face-centered cubic lattice structure and narrow size distributions.

Argon mediates protection by interleukin-8 suppression via a TLR2/TLR4/STAT3/NF-κB pathway in a model of apoptosis in neuroblastoma cells invitro and following ischemia-reperfusion injury in rat retina invivo.

Argon has recently come into scientific focus as a neuroprotective agent. The underlying neuroprotective mechanism remains unknown although toll-like receptors were recently suggested to play an important role. We hypothesized that TLR-associated downstream transcription factors are responsible for argon's effects, leading to anti-apoptotic and anti-inflammatory properties. Apoptosis was induced in human neuroblastoma cells. Immediately afterwards, argon treatment (75 Vol% for 2h) was initiated. Cells were analyzed, measuring mitochondrial membrane potential, reactive-oxygen-species, annexin-V/propidium iodide staining, transcription factor phosphorylation and binding activity as well as protein and mRNA expression of interleukins. Argon's invivo effects were analyzed by quantification of retinal ganglion cell density, mRNA expression, serum cytokine analysis and immunohistochemistry after retinal ischemia reperfusion injury (IRI) in rats. Argon diminished rotenone-induced kappa-light-chain-enhancer' of activated B-cells (NF-κB) and signal transducer and activator of transcription 3 (STAT3) but not STAT5 or cAMP-response element-binding protein (CREB) phosphorylation and DNA-binding activity. Argon treatment attenuated apoptosis by preservation of mitochondrial membrane potential and decline in reactive oxygen species (ROS) generation. NF-κB and STAT3 inhibition, as well as TLR2 and TLR4 inhibition reversed argon's effects on IL-8 mRNA expression. Argon attenuated rotenone-induced IL-8 protein and mRNA expression invitro. Inhibition of TLR2 and 4 attenuated argon's protective effect invivo reducing IRI driven retinal IL-8 expression. IL-8 expression was found in the retina in co-localization with Müller cells and retinal ganglion cells. Argon mediates its neuroprotective effects by TLR-mediated regulation of transcription factors NF-κB and STAT3, thus decreasing interleukin-8 expression invitro and invivo. These findings may open up new opportunities to effectively treat cerebral ischemia and reperfusion injury through the inhalation of argon. Argon exerts its protective effects invitro and in vivo via toll-like receptors TLR2 and TLR4 signaling, followed by alteration of downstream enzymes. In conclusion, argon mediates its beneficial effects by suppression of STAT3 and NF-κB phosphorylation and subsequent suppression of interleukin IL-8 protein expression. These novel findings may open up opportunities for argon as a therapeutic agent, particularly in the treatment of neuronal injury. Cover image for this issue: doi: 10.1111/jnc.13334.

927 Argon Plasma Coagulation Treatment of Intraductal Papillary Mucinous Neoplasm of Biliary Track: An Alternative Approach

927 Argon Plasma Coagulation Treatment of Intraductal Papillary Mucinous Neoplasm of Biliary Track: An Alternative Approach

Implant Abutment Cleaning by Plasma of Argon: 5-Year Follow-Up of a Randomized Controlled Trial.

Contamination of implant abutments could potentially influence the peri-implant tissue inflammatory response. The aim of the present study is to assess the radiographic bone changes around customized, platform-switched abutments placed according to the "one-abutment-one-time" protocol, with and without plasma of argon cleaning treatment. Thirty healthy patients with thin gingival biotype (<1 mm) and history of periodontal disease received one maxillary implant each. Immediately before abutment connection, patients were randomly assigned to control group (cleaning protocol by steaming) or test group (plasma of argon treatment). Outcome measures were: 1) success rate of implants and prostheses; 2) biologic and prosthetic complications; 3) peri-implant marginal bone loss (MBL); 4) esthetic and periodontal parameters; and 5) patient satisfaction. Neither implants nor prostheses were lost in either group at the 5-year follow-up examination. Overall, both groups showed a slight amount of peri-implant bone loss from baseline to 5 years. A statistically higher mean MBL was found in the control group compared with the test group at 6, 24, and 60 months after crown connection. Nevertheless, during the entire follow-up period, intragroup comparison demonstrated statistically significant mean MBL in the control group, but not in the test group. The test group showed a higher mean gain at the soft tissue margin, but not for the papilla. All implants showed good periodontal parameters, with no significant differences between groups. Plasma of argon could be used to disinfect implant abutments before insertion to minimize future peri-implant bone resorption.

Argon protects against hypoxic-ischemic brain injury in neonatal rats through activation of nuclear factor (erythroid-derived 2)-like 2.

Perinatal hypoxic ischaemic encephalopathy (HIE) has a high mortality rate with neuropsychological impairment. This study investigated the neuroprotective effects of argon against neonatal hypoxic-ischaemic brain injury.In vitro cortical neuronal cell cultures derived from rat foetuses were subjected to an oxygen and glucose deprivation (OGD) challenge for 90 minutes and then exposed to 70% argon or nitrogen with 5% carbon dioxide and balanced with oxygen for 2 hours.In vivo, seven-day-old rats were subjected to unilateral common carotid artery ligation followed by hypoxic (8% oxygen balanced with nitrogen) insult for 90 minutes. They were exposed to 70% argon or nitrogen balanced with oxygen for 2 hours. In vitro, argon treatment of cortical neuronal cultures resulted in a significant increase of p-mTOR and Nuclear factor (erythroid-derived 2)-like 2(Nrf2) and protection against OGD challenge. Inhibition of m-TOR through Rapamycin or Nrf2 through siRNA abolished argon-mediated cyto-protection. In vivo, argon exposure significantly enhanced Nrf2 and its down-stream effector NAD(P)H Dehydrogenase, Quinone 1(NQO1) and superoxide dismutase 1(SOD1). Oxidative stress, neuroinflammation and neuronal cell death were significantly decreased and brain infarction was markedly reduced. Blocking PI-3K through wortmannin or ERK1/2 through U0126 attenuated argon-mediated neuroprotection.These data provide a new molecular mechanism for the potential application of argon as a neuroprotectant in HIE.

Plasma Treatment of Silver Impregnated Mesoporous Aluminosilicate Nanoparticles for Adsorptive Desulfurization

We report a regenerable adsorbent for the removal of refractory organosulfur compounds from fossil fuels. The material is composed of well-dispersed silver nanoparticles confined within the mesochannels of aluminum-doped MCM-41 nanoparticles. With an average initial desulfurization capacity of 15 mg S·g–1, 79% desulfurization capacity is retained after six cycles for the removal of dibenzothiophene from n-decane. The addition of intraframework aluminum to form a mesoporous aluminosilicate nanoparticle (MASN) aids in the retention and dispersion of silver ions within the mesochannels (Ag-MASN). The nanoparticles are subsequently reduced by glow discharge plasma treatment in argon (PT-Ag-MASN). The size dispersion, surface area, and structural integrity were characterized by scanning electron microscopy, annular dark-field scanning transmission electron microscopy (ADF-STEM), nitrogen adsorption analysis (BET), and powder X-ray diffraction. Silver nanoparticle formation within the mesochannels of MASN was confirmed by ADF-STEM and diffuse reflectance UV–vis spectroscopy. Model fuel testing revealed that PT-Ag-MASN had the highest regeneration capacity after six cycles compared to non-plasma-treated (Ag-MASN) and aluminum-free materials (Ag-MSN and PT-Ag-MSN). Initial testing of the military jet fuel JP-8 also shows a high desulfurization capacity of 41 mg S·g–1.

In Vitro Analysis of Fibronectin-Modified Titanium Surfaces.

BackgroundGlow discharge plasma (GDP) procedure is an effective method for grafting various proteins, including albumin, type I collagen, and fibronectin, onto a titanium surface. However, the behavior and impact of titanium (Ti) surface modification is yet to be unraveled.PurposeThe purpose of this study is to evaluate and analyze the biological properties of fibronectin-grafted Ti surfaces treated by GDP.Materials and MethodsGrade II Ti discs were initially cleaned and autoclaved to obtain original specimens. Subsequently, the specimens were GDP treated and grafted with fibronectin to form Ar-GDP (Argon GDP treatment only) and GDP-fib (fibronectin coating following GDP treatment) groups. Blood coagulation test and MG-63 cell culture were performed to evaluate the biological effects on the specimen.ResultsThere was no significant difference between Ar-GDP and GDP-fib groups in blood compatibility analysis. While in the MTT test, cellular proliferation was benefited from the presence of fibronectin coating. The numbers of cells on Ar-GDP and GDP-fib specimens were greater than those in the original specimens after 24 h of culturing.ConclusionsGDP treatment combined with fibronectin grafting favored MG-63 cell adhesion, migration, and proliferation on titanium surfaces, which could be attributed to the improved surface properties.

The effect of atmosphere on reactions in Ni-Al green compacts subjected to thermal treatment in argon and air

The effect of atmosphere on reactions in Ni-Al green compacts subjected to thermal treatment in argon and air

Premaküler Subhiyaloid Hemoraji Gelişen Gebe Hastada Argon Laser Hiyaloidotomi Uygulaması

A 27-year-old female patient had applied to our clinic with a complaint of sudden onset, painless and persistent loss of vision in the left eye starting after an airplane flight 3 days ago. She was 26 weeks pregnant. Visual acuity in the left eye was counting fingers with a normal anterior segment examination. On fundus exam, subhyaloid hemorrhage covering the macular region between the vascular arcades was noticed. After giving information about the pregnancy, complication risks and other treatment alternatives, drainage of the subhyaloid hemorrhage with Argon laser membranotomy treatment was performed. After laser treatment, drainage of the hemorrhage into the vitreous cavity and instant improvement of vision was observed with no complications. The visual acuity was 0.3 (Snellen chart) the following day and 0.9 on the third postoperative day. Premacular hemorrhage was completely drained at one month. No complications were observed on 2 month follow-up. 532 nm lasers are present in most clinics and when proper parameters are selected, it proved to be an effective and safe alternative for treating premacular subhyaloid hemorrhage in our patient.

アルゴンプラズマ凝固法で治療した食道癌術後残頸部食道癌の1例

食道癌術後残頸部食道は，異時性食道癌の発生リスクが高い。今回われわれは，内視鏡治療を施行した食道癌術後残頸部食道癌の1例を経験した。症例は71歳，男性。術前診断cT1b N0の食道癌に対し，右開胸開腹胸部食道全摘3領域リンパ節郭清胸壁前経路胃管再建術を施行した。病理組織結果は，moderately differentiated squamous cell carcinoma，pT1a-LPM，ly0，v0，pN0であった。術後4年8カ月の上部消化管内視鏡検査で，食道入口部から頸部食道胃管吻合部におよぶ4/5周性の0-IIb病変を認め，生検にてsquamous cell carcinomaと診断された。頸部食道の広範な病変であったため，アルゴンプラズマ凝固法 (APC) を施行した。5年間で計8回のAPCを施行し，良好な局所制御を得た。頸部食道は生理的狭窄部であり内視鏡観察が難しく，進行癌で発見された場合の手術や化学放射線療法は侵襲の大きな治療となる。食道癌術後残頸部食道の観察は，field cancerizationの観点から，常に異時性食道癌を念頭におく必要がある。食道癌術後残頸部食道癌は，早期診断と適切な内視鏡治療の選択が重要である。

Soft Tissue Response to Titanium Abutments with Different Surface Treatment: Preliminary Histologic Report of a Randomized Controlled Trial.

The aim of this preliminary prospective RCT was to histologically evaluate peri-implant soft tissues around titanium abutments treated using different cleaning methods. Sixteen patients were randomized into three groups: laboratory customized abutments underwent Plasma of Argon treatment (Plasma Group), laboratory customized abutments underwent cleaning by steam (Steam Group), and abutments were used as they came from industry (Control Group). Seven days after the second surgery, soft tissues around abutments were harvested. Samples were histologically analyzed. Soft tissues surrounding Plasma Group abutments predominantly showed diffuse chronic infiltrate, almost no acute infiltrate, with presence of few polymorphonuclear neutrophil granulocytes, and a diffuse presence of collagenization bands. Similarly, in Steam Group, the histological analysis showed a high variability of inflammatory expression factors. Tissues harvested from Control Group showed presence of few neutrophil granulocytes, moderate presence of lymphocytes, and diffuse collagenization bands in some sections, while they showed absence of acute infiltrate in 40% of sections. However, no statistical difference was found among the tested groups for each parameter (p > 0.05). Within the limit of the present study, results showed no statistically significant difference concerning inflammation and healing tendency between test and control groups.