[Physiology of the wine yeasts. V. Carbon dioxide production by Fendant wine yeasts in nitrogen or in argon, air and nitrogen or in mixture of argon and air].
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Argon↗
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Concerning apparent similarity of structures of fluoropolymer surfaces exposed to an argon plasma or argon ion beam.
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Argon↗
Washin and washout curves of helium, neon, argon and SF 6 in nitrogen, helium and argon.
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Argon↗
The Ionization of Argon and Neon by Neutral Argon Beams.
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Journal Article↗
Measurements of cross sections for electron-impact excitation into the metastable levels of argon and number densities of metastable argon atoms.
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Journal Article↗
[Simultaneous recording of visual evoked potentials and ultrasonic responses to argon lasers from the visual cortex during argon photocoagulation].
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Evoked Potentials, Visual↗
Radiogenic argon distribution within a mineral grain: implications for dating of hydrothermal mineral-forming event in Sludyanka complex, Siberia, Russia.
Usually, in age-determination procedures, the experimenter is interested in the mean concentrations of parent and daughter substances. However, the structure of a solution of the Fick's diffusion equation enables one to specify a procedure, allowing, through macroscopic experiments, one to determine the distribution of radiogenic argon (as well as any of other isotopes) within a mineral grain. Argon, influenced in the geological past by a metamorphic event, has a half-sinusoidal distribution, whereas argon preserved in geological time has a rectangular distribution. The ratio of the quantity of argon of the first type to the total argon is called an alpha-factor. It is believed that this coefficient can be of great interest for geochronological studies, being a symptom of virtual Ar losses and the time instant, at which they happened. A laboratory procedure and a mathematical algorithm to determine the alpha-factor are developed. As an example, a determination of the alpha-factor on a vein-phlogopite from the well-studied Sludyanka deposit, Southern Baikal, Siberia, Russia, is described. Rb-Sr isochron age on phlogopite-calcite-apatite paragenetic assemblage yielded 460+/-7 Ma and is constrained by U-Pb zircon ages of 471+/-1 and 447+/-2 Ma, respectively, on an emplacement of early syenites and monzonites and later 'post-phlogopitic' pegmatites [E.B. Salnikova, S.A. Sergeev, A.B. Kotov, S.Z. Yakovleva, R.H. Steiger, L.Z. Reznitskiy, E.P. Vasil'ev. U-Pb zircon dating of granulite metamorphism in the Sludyanskiy complex, Eastern Siberia. Gondwana Res., 1, 195-205 (1998). L.Z. Reznitskii, G.P. Sandimirova, Y.A. Pakhol'chenko, S.V. Kuznetsova. The Rb-Sr age of phlogopite deposits in Sludyanka, southern Baikal region. Dokl. Earth Sci., 367, 711-713 (1999). L.Z. Reznitskii, A.B. Kotov, E.B. Salnikova, E.P. Vasil'ev, S.Z. Yakovleva, V.P. Kovach, A.M. Fedoseenko. The age and time span of the origin of phlogopite and lazurite deposits in the Southwestern Baikal area: U-Pb geochronology. Petrology, 8, 66-76 (2000).]. In this study, the phlogopite gave an apparent K-Ar age of 365.6+/-10.4 Ma which has no geological meaning. The alpha-factor of 0.27 was derived from a laboratory kinetic experiment. The age determined by the rectangularly distributed argon corresponded to alphax0.129 nmm3/g (total radiogenic argon in the sample)=94.17 nmm3/g, and an age of approximately 274 Ma (e.g. a period without any argon losses). Here, at the first sight, we deal with common argon losses not conjugated with any geological event, because after 447 Ma only lower temperature (in a range of 50-300 degrees C) hydrothermal processes were recorded. A paragenetic phlogopite-bearing vein mineral, hyalophane, having a disturbed Rb-Sr isotopic system, however, yielded 40Ar/39Ar subplateau age of 271+/-2 Ma [V.V. Ivanenko, M.I. Karpenko, M.A. Litsarev. Age of the Sludyanka phlogopite deposits (in Russian; data of the 39Ar-40Ar method). In Geological Series 5, pp. 92-98, Izvestiya Akademii Nauk SSSR, Moskva (1990).], marking similar timing of the K-Ar isotopic system closure. This indicates that K-Ar isotopic system in the phlogopite was not closed (or was partially reset) long after its crystallisation and closing of the Rb-Sr system, in spite of the fact that the crystal was not affected by processes having temperatures above the accepted closure temperatures for micas. There seems to have acted an exchange mechanism of OH-groups between surrounding fluid and hydrocrystal structure. Thus the argon loss did not occur, spontaneously, but argon particles seem to have been captured and carried to the mineral surface by vacancies formed during displacements of OH-groups.
Argon↗
Argon pneumoperitoneum is more dangerous than CO2 pneumoperitoneum during venous gas embolism.
UNLABELLED: We investigated the possibility of using argon, an inert gas, as a replacement for carbon dioxide (CO2). The tolerance of argon pneumoperitoneum was compared with that of CO2 pneumoperitoneum. Twenty pigs were anesthetized with enflurane 1.5%. Argon (n = 11) or CO2 (n = 9) pneumoperitoneum was created at 15 mm Hg over 20 min, and serial intravenous injections of each gas (ranging from 0.1 to 20 mL/kg) were made. Cardiorespiratory variables were measured. Transesophageal Doppler and capnographic monitoring were assessed in the detection of embolism. During argon pneumoperitoneum, there was no significant change from baseline in arterial pressure and pulmonary excretion of CO2, mean systemic arterial pressure (MAP), mean pulmonary artery pressure (PAP), or systemic and pulmonary vascular resistances, whereas CO2 pneumoperitoneum significantly increased these values (P < 0.05). During the embolic trial and from gas volumes of 2 and 0.2 mL/kg, the decrease in MAP and the increase in PAP were significantly higher with argon than with CO2 (P < 0.05). In contrast to CO2, argon pneumoperitoneum was not associated with significant changes in cardiorespiratory functions. However, argon embolism seems to be more deleterious than CO2 embolism. The possibility of using argon pneumoperitoneum during laparoscopy remains uncertain. IMPLICATIONS: Laparoscopic surgery requires insufflation of gas into the peritoneal cavity. We compared the hemodynamic effects of argon, an inert gas, and carbon dioxide in a pig model of laparoscopic surgery. We conclude that argon carries a high risk factor in the case of an accidental gas embolism.
Animals↗
Argon ion beam hemostasis with albumin after liver resection.
BACKGROUND: Bleeding is common after liver resection and establishing hemostasis with sutures or argon beam coagulation can be difficult. In our laboratory, concentrated albumin applied to the liver surface before argon beam coagulation improves sealing of the resected surface of the liver, including closure of blood vessels and ducts not generally seen with standard argon beam coagulation. METHODS: Domestic swine underwent heparinization, then laparotomy and wedge resection of the left medial segment of the liver, using finger fracture technique. Blood vessels and ducts 5 mm or greater were ligated. For achieving hemostasis, the animals were randomized to either a control group using argon beam coagulation alone (n = 15) or an albumin group using argon beam coagulation with concentrated 38% albumin (n = 13). After initial hemostasis, the resected liver surfaces were packed for 3 minutes. Repeated applications of argon beam coagulation with or without albumin were performed as needed, followed by 3 minutes of repacking, until complete hemostasis was achieved. Liver functions and blood counts were examined 4 days postoperatively. RESULTS: The albumin group was less likely to require repeat applications of argon beam coagulation than control animals (mean 0.5 versus 1.5 times, P = 0.006). The total time of argon beam coagulation was significantly shorter in the albumin group (mean 90 versus 154 seconds, P = 0.001). CONCLUSIONS: Adding albumin to the liver surface substantially increases the durability of the repaired surface and reduces the time needed to achieve stable hemostasis when compared with standard argon beam coagulation. Further investigations using this technique are warranted.
Albumins↗
Bond strength of a dentin bonding system using two techniques of polymerization: visible-light and argon laser.
OBJECTIVE: The aim of this work was to study one dentin-bonding system associated with posterior teeth restorative composite resin by means of tensile bond strength tests varying the technique of polymerization: visible light and argon laser. BACKGROUND DATA: Previous studies have demonstrated the ability of the argon laser to polymerize light-activated materials. METHODS: Sixty specimens were prepared by grinding the labial surface of bovine teeth embedded in acrylic resin. The dentin bonding system used was Single Bond (3M), which has a poliacenoic acid copolimer, associated with a posterior teeth restorative composite resin (Filtek P60, 3M). The bonding sites were treated according to the instruction of the manufacturers. The 60 teeth, duly embedded and ground, were assigned to four groups with 15 teeth each: group 1, the adhesive was light cured during 10 sec with visible light (Curing Light, 3M) with power density of 410 mW/cm2 and the composite resin was light cured during 20 sec with visible light; group 2, the adhesive and the composite resin were cured during 10 seconds with argon laser with 150 mW of power; group 3, the adhesive and the composite resin were cured during 10 sec with argon laser with 200 mW of power; and group 4, the adhesive and the composite resin were cured during 10 sec with argon laser with 250 mW of power. The composite resin was light cured in layers of 1 mm of thickness until the model of teflon with 3 mm in height was completely filled. RESULTS: The tensile bond strength test was performed in a Mini-Instron (model 4442) and the results for group 1 were 19.75 MPa (+/-4.65), group 2 were 16.09 MPa (+/-7.27), group 3 were 11.56 MPa (+/-4.50), and group 4 were 11.90 MPa (+/-5.78). CONCLUSIONS: One can conclude that the tensile bond strength promoted by the polymerization with visible light presented greater tensile bond strength than the polymerization with argon laser with 200 mW and 250 mW, but there was no significant difference between visible light and argon laser with 150 mW. There was no significant difference between argon laser with 150 mW and argon laser with 200 mW or 250 mW.
Animals↗
Sigmoid cystoplasty with argon beam without mucosa.
PURPOSE: Intestinal bladder augmentations have well recognized complications, including mucus production, metabolic abnormalities and perforation. These complications may be avoided if the intestinal mucosa is not incorporated in the urinary tract. We report our experience with sigmoid cystoplasty without mucosa using argon beam, and describe the clinical, urodynamic, ultrasound and pathological results. MATERIALS AND METHODS: We performed sigmoid cystoplasty without mucosa in 26 patients and with argon beam over the mucosa before it was removed in 6 boys and 4 girls with a mean age of 8 years (range 3 to 14). All patients had neurogenic bladder as the initial disease. Indications for augmentation were poor bladder compliance, low bladder capacity, hydronephrosis and urinary incontinence. Mean followup was 18 months (range 8 to 40) and included ultrasound, urodynamic evaluation, renal function and clinical assessment. In all patients intraoperative biopsies were done. In 8 of the 10 patients endoscopic biopsies of the augmented segment were obtained between 6 months and 2 years postoperatively. The operation consisted of the Goodwin technique without mucosa, which was treated with argon beam before it was removed. RESULTS: The 10 patients are dry on intermittent clean catheterization with intervals of greater than 4 hours. There have been no clinical urinary tract infections. Two patients presented with peristaltic contractions and no symptoms. Bladder capacity increased from 80 (range 45 to 200) to 300 (220 to 400) ml., and mean postoperative compliance was 15 ml./cm. H2O (range 9 to 38). There were no significant changes in the urodynamic data between patients treated with sigmoid cystoplasty without mucosa only and with argon beam. Intraoperative biopsies after treatment with argon beam showed damaged mucosa and muscularis mucosa, and intact serosa, muscularis and submucosa layers. On the 8 argon beam postoperative biopsies the sigmoid submucosa was covered with a pseudostratified metaplasia of connective tissue with collagen fibers without scars (trichromic technique). CONCLUSIONS: Sigmoid cystoplasty without mucosa with argon beam is easy to perform. The clinical and urodynamic results have been satisfactory, and use of argon beam prevents postoperative bleeding and residual glands.
Adolescent↗
A comparison of neodymium: YAG and argon laser iridotomies.
A prospective short-term clinical study evaluated argon and Q-switched neodymium:YAG laser iridotomies in 40 eyes of 20 patients with primary chronic angle-closure glaucoma. All patients had bilateral iridotomies with one eye randomly assigned to argon laser and the fellow eye to neodymium:YAG laser therapy. In all eyes a patent iridotomy was created in one treatment session. A mean of 12 +/- 11 and 0.033 +/- 0.025 J were needed for iridotomy formation in argon and neodymium:YAG treated eyes respectively. No neodymium:YAG and six (30%) argon iridotomies had marked closure requiring retreatment. Immediate postoperative intraocular pressure elevation greater than 10 mmHg was seen in seven (35%) argon and six (30%) neodymium:YAG-treated eyes. Nine (45%) eyes treated with the neodymium:YAG laser had bleeding from the iridotomy site. No acute lens damage was found in the neodymium:YAG eyes while seven (35%) lenses in the argon group had focal opacities. Seven (35%) neodymium:YAG and five (25%) argon treated eyes had focal nonprogressive corneal opacities above the iridotomy site. Specular microscopy showed a significant central corneal endothelial loss in argon laser treated eyes. No eyes had detectable retinal damage.
Adult↗
Argon plasma coagulation prevents variceal recurrence after band ligation of esophageal varices: preliminary results of a prospective randomized trial.
BACKGROUND: Endoscopic variceal ligation is an established procedure for eradication of esophageal varices. However, varices frequently recur after endoscopic variceal ligation. Argon plasma coagulation has been used as supplemental treatment for eradication of varices and for prevention of variceal recurrence in small uncontrolled series. The aim of this study was to determine whether argon plasma coagulation is effective in reducing variceal recurrence after endoscopic variceal ligation. METHODS: Thirty patients with cirrhosis, a history of acute esophageal variceal bleeding, and eradication of varices by endoscopic variceal ligation were randomized to argon plasma coagulation (16 patients) or observation (14 patients). The 2 groups were similar with respect to all background variables including age, Child-Pugh score, presence of gastric varices, and degree of portal hypertensive gastropathy. In the argon plasma coagulation group, the entire esophageal mucosa 4 to 5 cm proximal to the esophagogastric junction was thermocoagulated circumferentially with argon plasma coagulation in 1 to 3 sessions performed at weekly intervals. Endoscopy was performed every 3 months to check for recurrence of varices in both groups. RESULTS: During the course of the study, no serious complication was noted. After argon plasma coagulation, transient fever occurred in 13 patients and 8 complained of dysphagia or retrosternal pain/discomfort. Mean follow-up for all patients was 16 months (range 9-28 months). No recurrence of varices or variceal hemorrhage was observed in the argon plasma coagulation group, whereas varices recurred in 42.8% (6/14) of the patients in the control group (p < 0.04) and bleeding recurred in 7.2% (1/14). CONCLUSIONS: Argon plasma coagulation of the distal esophageal mucosa after eradication of esophageal varices by endoscopic variceal ligation is safe and effective for reducing the rate of variceal recurrence.
Argon↗
Argon laser curing of fluoride-releasing pit and fissure sealant: in vitro caries development.
The purpose of this study was to compare the effect of argon laser polymerization of a visible-light-cured, fluoride-releasing pit and fissure sealant on caries development in vitro. A total of twelve caries-free premolar and molar teeth was selected, and underwent a fluoride-free prophylaxis and soft tissue debridement. Cavity preparations were placed in buccal and lingual surfaces. Lingual cavity preparations were filled with the fluoride-releasing sealant (UltraSealXTplus, Ultradent) and visible light cured per the manufacturer's recommendation. Buccal preparations were filled with the fluoride-releasing sealant and argon laser cured (231 mW, 12 J/cm2 for 10 seconds). Following sealant placement, the teeth were sectioned into buccal and lingual halves. An acid-resistant varnish was placed leaving a 1 mm rim of exposed surface enamel adjacent to the sealant. The specimens were then thermocycled in synthetic saliva (500 cycles, 5 to 50 degrees C). In vitro caries lesions were formed (2.2 mM Ca, 2.2 mM PO4, 50 mM acetic acid, 5 ppm fluoride, pH 3.95). Longitudinal sections (five sections per tooth half) were obtained and evaluated by polarized light microscopy for mean outer surface lesion depths and frequency of wall lesions. Mean primary surface (outer) lesion depth was significantly decreased (ANOVA, DMR, P < .05) for the fluoride-releasing sealant with argon laser polymerization (152 +/- 16 um) when compared with visible light curing (211 +/- 23 um). Likewise, wall lesion frequency was substantially reduced for the argon laser polymerized sealants (17 percent) when compared with that for the visible light polymerized sealants (24 percent, ANOVA, DMR, P < .05). Argon laser polymerization of a fluoride-releasing pit and fissure sealant improved caries resistance markedly in the surface enamel adjacent to the sealant material. Argon laser curing enhanced the caries protective ability of the sealant along the enamel-resin cavosurface, as noted by a decrease in wall lesion frequency. Argon laser polymerization provides further caries protection against a cariogenic challenge over that afforded by fluoride-releasing sealants. Caries development around a sealant material may be hampered by the combination of fluoride release from the sealant and argon laser polymerization.
Acetates↗
Clinical application of argon plasma coagulation in endoscopic hemostasis for non-ulcer non-variceal gastrointestinal bleeding--a pilot study in Taiwan.
BACKGROUND/AIMS: Argon plasma coagulation is an innovative non-touch electrocoagulation technique. A broad spectrum of indications has been proposed for argon plasma coagulation since its introduction into endoscopy in 1991. The aim of this study is to evaluate the efficacy of utilizing argon plasma coagulation in the endoscopic hemostasis of non-ulcer, non-variceal gastrointestinal bleeding in Taiwan. METHODOLOGY: A total of 26 consecutive patients (15 men, 11 women; mean age: 67.6 years) underwent argon plasma coagulation treatment between May 1999 and August 2000. Causes of bleeding included angiodysplasia in 3, tumor bleeding in 8, radiation colitis in 11, watermelon stomach in 1, Osler-Weber-Rendu syndrome in 1, and post-intervention in 2. Argon plasma coagulation was performed in 2 patients with bleeders in the esophagus, 10 in the stomach, 1 in the stomach and duodenum, and 13 in the colon. RESULTS: A total of 38 sessions of application in 26 patients were performed. Successful endoscopic argon plasma coagulation treatment was achieved in 21 (80.8%) patients. Neither complication nor mortality related to argon plasma coagulation was observed in these 26 patients. CONCLUSIONS: Argon plasma coagulation is a safe, efficacious, and low-cost hemostatic modality for non-ulcer, non-variceal gastrointestinal bleeding. It is mandatory to establish a comparative trial with other treatment modalities with a longer follow-up in the future.
Adult↗
Corneal transmissibility of diode versus argon lasers and their photothermal effects on the cornea and iris.
PURPOSE: Diode laser (810 nm) may possess theoretical advantages over the argon blue-green laser (488 nm) for iridotomy/iridoplasty in an eye with oedematous cornea, such as the acute angle-closure glaucoma (AACG) patient, because of better diode laser tissue penetration in opaque media. We assessed the transmissibility of diode and argon lasers through corneas of varying clarity and evaluated the histopathological features of cornea and iris burns produced by these lasers. METHODS: The transmission of diode and argon lasers through human donor corneal buttons of three grades of clarity--clear, intermediate, and hazy--were compared. Corneal buttons of these varying levels of clarity were also treated with argon and diode lasers, with the beams deliberately focused onto the mid-stroma to assess their photothermal effects. Exposed pigmented irides from whole human eyes were treated directly with argon and diode lasers. The lasers were delivered via slit-lamp systems and the energy settings used were 1000 mW for argon and 980 mW for diode; spot sizes for both lasers were 100 microm, with exposure durations of 0.1 s. Light microscopy studies of these tissues were performed. RESULTS: Transmissibility of diode laser in clear, intermediate, and hazy corneas were 89, 87 and 85% respectively and was significantly superior to argon laser (78, 73 and 70% respectively; P < 0.001, paired Student's t-test). Diode laser did not produce morphological changes in all three grades of corneas whereas argon-laser-treated hazy corneas showed photothermal damage. Both lasers produced deep iris burns, with the diode laser tending to produce deeper burns. CONCLUSION: Our findings suggest that diode laser may be the ideal laser for iridotomy/iridoplasty in the AACG patient with hazy cornea.
Acute Disease↗
Packing density and structure effects on energy-transfer dynamics in argon collisions with organic monolayers.
A combined experimental and molecular-dynamics simulation study has been used to investigate energy-transfer dynamics of argon atoms when they collide with n-alkanethiols adsorbed to gold and silver substrates. These surfaces provide the opportunity to explore how surface structure and packing density of alkane chains affect energy transfer in gas-surface collisions while maintaining the chemical nature of the surface. The chains pack standing up with 12 degrees and 30 degrees tilt angles relative to the surface normal and number densities of 18.9 and 21.5 A(2)molecule on the silver and gold substrates, respectively. For 7-kJmol argon scattering, the two surfaces behave equivalently, fully thermalizing all impinging argon atoms. In contrast, these self-assembled monolayers (SAMs) are not equally efficient at absorbing the excess translational energy from high-energy, 35 and 80 kJmol, argon collisions. When high-energy argon atoms are scattered from a SAM on silver, the fraction of atoms that reach thermal equilibrium with the surface and the average energy transferred to the surface are lower than for analogous SAMs on gold. In the case of argon atoms with 80 kJmol of translational energy scattering from long-chain SAMs, 60% and 45% of the atoms detected have reached thermal equilibrium with the monolayers on gold and silver surfaces, respectively. The differences in the scattering characteristics are attributed to excitation efficiencies of different types of surface modes. The high packing density of alkyl chains on silver restricts certain low-energy degrees of freedom from absorbing energy as efficiently as the lower-density monolayers. In addition, molecular-dynamics simulations reveal that the extent to which argon penetrates into the monolayer is related to packing density. For argon atoms with 80-kJmol incident energy, we find 16% and 7% of the atoms penetrate below the terminal methyl groups of C(10) SAMs on gold and silver, respectively.
Journal Article↗
Endoscopic ablation of Barrett's oesophagus: a randomized-controlled trial of photodynamic therapy vs. argon plasma coagulation.
BACKGROUND: Barrett's oesophagus is the major risk factor for oesophageal adenocarcinoma. 5-Aminlevulinic acid-induced photodynamic therapy and argon plasma coagulation have been shown to be effective for ablating Barrett's oesophagus, but a comparative trial of these two modalities has not been reported. AIMS: To compare photodynamic therapy and argon plasma coagulation for the ablation of Barrett's oesophagus. METHODS: A total of 68 patients (54 male, 14 female; median age 61) with Barrett's oesophagus were randomized to photodynamic therapy (n = 34) or argon plasma coagulation (n = 34). Photodynamic therapy was performed using 5-aminlevulinic acid (30 mg/kg) and red light. Argon plasma coagulation was administered at a power setting of 65 W. Multiple treatment sessions were performed, with follow-up to 24 months. RESULTS: All patients showed a macroscopic reduction in the area of Barrett's oesophagus. This was greatest in the argon plasma coagulation group with 33 of 34 (97%) ablated, compared with 17 of 34 (50%) in the photodynamic therapy group; in the remainder, there was a reduction in the length of Barrett's oesophagus (median 50%, range: 5-90). Buried glands were found in 24% of photodynamic therapy patients, and in 21% of argon plasma coagulation patients. The median follow-up is 12 months (range: 6-24). CONCLUSIONS: Photodynamic therapy and argon plasma coagulation are both effective for ablating Barrett's oesophagus. Argon plasma coagulation appears more effective than photodynamic therapy, but the impact of both on carcinoma development requires larger studies with long-term follow-up.
Adult↗