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1

Symptomatic gastric inlet patches in children treated with argon plasma coagulation: a case series  

PubMed Central

The pathologic potential of gastric inlet patches is now being recognized. A recent adult study has shown the effectiveness of argon plasma coagulation in ablating the patch and the associated symptoms. There are no reports of ablation in children. We report a case series of successful argon plasma coagulation of gastric inlet patches and their symptoms in 5 children.

Chanis, Ricardo; Khoshoo, Vikram

2012-01-01

2

Large sessile colonic adenomas: use of argon plasma coagulator to supplement piecemeal snare polypectomy  

Microsoft Academic Search

Background: Residual adenoma is frequently found at the site of endoscopically resected large sessile adenomas on follow-up examination. We evaluated the efficacy of a thermal energy source, the argon plasma coagulator, to destroy visible residual adenoma after piecemeal resection of sessile polyps. Methods: Seventy-seven piecemeal polypectomies with or without the use of argon plasma coagulator were analyzed retrospectively. All polyps

Jusuf Zlatanic; Jerome D. Waye; Peter S. Kim; Peter J. Baiocco; Gilbert W. Gleim

1999-01-01

3

Multiple inflammatory gastric polyps treated by endoscopic polypectomy with argon plasma coagulation in a dog.  

PubMed

An 11-year-old spayed female miniature dachshund was evaluated for a 2-month history of chronic vomiting. Abdominal ultrasonography revealed a heterogeneous mass in the pyloric region. Contrast upper gastrointestinal radiography demonstrated impairment of gastric outflow. Endoscopic examination revealed multiple polyps at the gastric pylorus. The pyloric polyps were variable in size, sessile-shaped and pedunculated. Initially, endoscopic polypectomy was attempted, but all the polyps could not be completely resected. Thus, endoscopic polypectomy with argon plasma coagulation was performed to cauterise the lesions. The histopathological diagnosis of the lesions was inflammatory polyps, and a moderate number of Helicobacter spp. was revealed. After the argon plasma coagulation treatment, the dog did not vomit, and improvement of clinical signs was maintained for 13 months. Endoscopic polypectomy with argon plasma coagulation may be useful for mixtures of sessile and pedunculated polyps. The present report may provide a basis for further studies of argon plasma coagulation treatment for canine gastrointestinal polyps. PMID:23398431

Teshima, T; Matsumoto, H; Michishita, M; Takahashi, K; Koyama, H

2013-02-09

4

Argon plasma coagulation of hemorrhagic solitary rectal ulcer syndrome.  

PubMed

Solitary ulcer syndrome (SUS) is a rare disorder that may provoke hematochezia. Argon plasma coagulation (APC) is used in a wide range of gastrointestinal bleeding. We experienced APC in a patient with a bleeding gigantic SUS: a 64-year-old woman who developed a SUS at 60. After 3 years, recurrent hematochezia, secondary anemia, and rectal pain occurred. Endoscopy revealed a large rectal bleeding ulcer. Moreover, the pain led the patient to assume analgesics. These conditions stimulated us to treat this ulcer with APC within 4 sessions; each session spaced out at 30-day intervals. The patient experienced and maintained the following benefits: (1) resolution of bleeding and secondary anemia after the first session, (2) reduction of ulcer depth, disappearance of pain and analgesic withdrawal at the end of the cycle, (3) almost complete endoscopic healing of the ulcer after 9 months of follow-up. This experience suggests that APC may represent a therapeutic approach for bleeding SUS even if controlled studies are necessary before recommending it as acceptable treatment. PMID:14564186

Stoppino, Vincenzo; Cuomo, Rosario; Tonti, Paolo; Gentile, Marco; De Francesco, Vincenzo; Muscatiello, Nicola; Panella, Carmine; Ierardi, Enzo

5

Argon plasma coagulation prevents variceal recurrence after band ligation of esophageal varices: Preliminary results of a prospective randomized trial  

Microsoft Academic Search

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

Livio Cipolletta; Maria Antonia Bianco; Gianluca Rotondano; Riccardo Marmo; Costantino Meucci; Roberto Piscopo

2002-01-01

6

Prospective comparison of argon plasma coagulator and heater probe in the endoscopic treatment of major peptic ulcer bleeding  

Microsoft Academic Search

Background: Argon plasma coagulator was prospectively compared with heater probe in patients with bleeding peptic ulcers. Methods: Forty-one patients with major stigmata of ulcer hemorrhage were randomly assigned to receive either heater probe (n = 20) or argon plasm coagulation (n = 21) treatment; 40% had active bleeding and 60% had a nonbleeding visible vessel in the ulcer crater. The

Livio Cipolletta; Maria Antonia Bianco; Gianluca Rotondano; Roberto Piscopo; Antonio Prisco; Maria Lucia Garofano

1998-01-01

7

[Use of argon plasma coagulation in digestive endoscopy: a concise review].  

PubMed

Argon plasma coagulation (APC) is a non-contact thermal method of hemostasis that has generated much attention in recent years. This endoscopic procedure is used primarily to control bleeding from lesions in the gastrointestinal tract, and also sometimes to debulk tumours in the case of patients for whom surgery is not recommended. APC involves the use of a jet of ionized argon gas (plasma) that is directed through a probe passed through the endoscope. The probe is placed at some distance from the lesion, and tissue damage is limited to superficial layers. The depth of coagulation is usually only a few millimetres. Theoretical advantages of APC include facility application, speedy treatment of multiple lesions in the case of angiodysplasias or wide areas (the base of resected polyps or tumor bleeding), safety due to reduced depth of penetration, and lower cost compared to laser. PMID:23306759

Zippi, M; Traversa, G; Cocco, A; Pica, R; Cassieri, C; Avallone, E V; Occhigrossi, G

2012-11-01

8

Topical estrogens combined with argon plasma coagulation in the management of epistaxis in hereditary hemorrhagic telangiectasia.  

PubMed

The aim of this study was to assess the value of topically applied estrogens in patients with hereditary hemorrhagic telangiectasia. Twenty-six patients with this disorder were treated with argon plasma coagulation and randomized into 2 groups: group A, which had postoperative application of estriol ointment (n = 14), and group B, which had postoperative application of dexpanthenol ointment (n = 12). Over a period of 12 months, the frequency and intensity of bleeding, the patient's satisfaction, and the success of the treatment were evaluated with a questionnaire. Before the operation, more than 90% of the patients in both groups complained of daily episodes of epistaxis. Twelve months after treatment, the frequency and intensity of bleeding had significantly decreased in group A as compared to group B. Of the patients in group A, 93% were satisfied with the treatment. Of the patients in group B, only 42% were satisfied with the treatment. In both groups, more than 90% of the patients were willing to undergo the same treatment again. The combined treatment approach with argon plasma coagulation and topical estriol enables us to significantly prolong the hemorrhage-free interval. PMID:11913682

Bergler, Wolfgang; Sadick, Haneen; Gotte, Karl; Riedel, Frank; Hörmann, Karl

2002-03-01

9

Argon beam coagulation systems.  

PubMed

We evaluated the two argon-enhanced coagulation (AEC) systems currently on the market from two different manufacturers, basing our ratings primarily on performance and safety and considering the clinical perspectives gained from discussions with surgeons who use these units. We rated both units Acceptable. Because one unit has characteristics that provide a potential safety advantage (i.e., it produces lower gas pressure at the tissue and limits certain gas flow/power combinations), we ranked it slightly higher than the other unit. However, sufficient laboratory and clinical studies must still be carried out to assess the risk of gas embolism with these and future systems. PMID:2211173

1990-09-01

10

A case of canine multiple inflammatory colorectal polyps treated by endoscopic polypectomy and argon plasma coagulation.  

PubMed

Endoscopic polypectomy and argon plasma coagulation (APC) were performed in a refractory case of inflammatory colorectal polyps in a 7-year-old male Miniature Dachshund. Colonoscopic examination revealed a large sessile polyp and multiple diffuse small polyps, localized to the descending colon and rectum. The case showed a poor therapeutic response to prednisolone and cyclosporine. Under anesthesia, piecemeal resections were performed by polypectomy. APC was carried out to cauterize the polyp remnants. After treatment, reduction of the lesions and the improvement in clinical signs were observed, without recurrence of lesions for at least 10 months. Endoscopic treatment by polypectomy and APC is suggested to be a therapeutic option for refractory cases of inflammatory colorectal polyps in dogs. PMID:22104397

Tsukamoto, Atsushi; Ohno, Koichi; Irie, Mitsuhiro; Ohmi, Aki; Maeda, Shingo; Nakashima, Ko; Fukushima, Kenjiro; Fujino, Yasuhito; Uchida, Kazuyuki; Tsujimoto, Hajime

2011-11-22

11

Argon plasma coagulation ablation versus endoscopic surveillance of Barrett's esophagus: late outcomes from two randomized trials.  

PubMed

Background and study aim: Argon plasma coagulation (APC) has been used to ablate dysplastic and nondysplastic Barrett's esophagus. We determined the longer-term efficacy of APC ablation within two randomized controlled trials of APC versus surveillance for Barrett's esophagus in patients in whom gastroesophageal reflux was controlled by either surgery or proton pump inhibitors.Patients and methods: 129 patients (surgical trial 70, medical trial 59) with Barrett's esophagus (nondysplastic or low grade dysplasia) were randomly allocated to either ablation using APC or to continuing endoscopy surveillance. Outcomes were determined at three time points: short-term (12 months), mid-term (42 - 75 months) and long-term (> 84 months). Results: In the APC groups, initial ablation of > 95 % of the Barrett's esophagus was achieved in 61 of 63 patients; the > 95 % ablation persisted in 47 of 56 patients at short-term follow-up, in 33 of 49 at mid-term and in 21 of 32 at long-term follow-up. In the surveillance groups, the length of Barrett's esophagus reduced from a mean of 4.2 cm to 2.7 cm at long-term follow-up. High grade dysplasia (HGD) developed in 1 patient in the APC groups and in 3 in the surveillance groups. Low grade dysplasia developed in 1 APC patient and in 6 surveillance patients.Conclusions: APC ablation reduced the extent of Barrett's esophagus, and this reduction was maintained in some patients at longer-term follow-up. However, progression to HGD can still occur despite APC ablation, suggesting endoscopic surveillance is still required.Clinical trial registration: ACTRN012607000293460 and ACTRN12607000292471 (Australian Clinical Trials Registry). PMID:24019134

Sie, Corina; Bright, Tim; Schoeman, Mark; Game, Philip; Tam, William; Devitt, Peter; Watson, David

2013-09-09

12

Argon plasma coagulation as an alternative treatment for bronchopleural fistulas developed after sleeve pneumonectomy.  

PubMed

We present a case that used argon plasma coagulation (APC) for the healing of bronchopleural fistulas (BPF), which most probably developed secondary to tracheobronchial anastomotic failure (TBAF). We aimed to show this procedure as an alternative treatment for the small fistulas that could develop after pneumonectomy. In a 56-year old male patient, right upper lobe squamous cell carcinoma was detected in 2009. Sleeve pneumonectomy was done because of the carina and major fissure invasion. There was no morbidity in the early post-operative period. The patient was discharged on the seventh day without any problems. Three cycles of chemotherapy were applied. In the third month after operation, the patient complained of a cough, and odorous sputum starting 15 days earlier. Two fistula orifices (1 and 3 mm) were detected in the fibre-optic bronchoscopy (FOB). No sign of tumour recurrences was detected in either chest computed tomography (CT) or FOB. BPF had entered the mediastinal chamber, which isolated the infection from the pleural cavity. The APC procedure was applied using FOB under local anaesthesia. The processing time was 30 min. There were no complications during or after the procedure. FOB was repeated 30 days later, and none of the previously opened orifices were observed. The patient was followed up for 18 months without any symptoms. APC was generally used for the treatment of oesophageal and intestinal fistula. We could not find any cases in the literature about APC application to treat BPF. APC could be an alternative treatment for the selected cases with small, uncomplicated BPF. PMID:22374288

Aynaci, Engin; Kocatürk, Celalettin Ibrahim; Yildiz, Pinar; Bedirhan, Mehmet Ali

2012-02-27

13

Argon plasma coagulation as an alternative treatment for bronchopleural fistulas developed after sleeve pneumonectomy  

PubMed Central

We present a case that used argon plasma coagulation (APC) for the healing of bronchopleural fistulas (BPF), which most probably developed secondary to tracheobronchial anastomotic failure (TBAF). We aimed to show this procedure as an alternative treatment for the small fistulas that could develop after pneumonectomy. In a 56-year old male patient, right upper lobe squamous cell carcinoma was detected in 2009. Sleeve pneumonectomy was done because of the carina and major fissure invasion. There was no morbidity in the early post-operative period. The patient was discharged on the seventh day without any problems. Three cycles of chemotherapy were applied. In the third month after operation, the patient complained of a cough, and odorous sputum starting 15 days earlier. Two fistula orifices (1 and 3 mm) were detected in the fibre-optic bronchoscopy (FOB). No sign of tumour recurrences was detected in either chest computed tomography (CT) or FOB. BPF had entered the mediastinal chamber, which isolated the infection from the pleural cavity. The APC procedure was applied using FOB under local anaesthesia. The processing time was 30 min. There were no complications during or after the procedure. FOB was repeated 30 days later, and none of the previously opened orifices were observed. The patient was followed up for 18 months without any symptoms. APC was generally used for the treatment of oesophageal and intestinal fistula. We could not find any cases in the literature about APC application to treat BPF. APC could be an alternative treatment for the selected cases with small, uncomplicated BPF.

Aynac?, Engin; Kocaturk, Celalettin Ibrahim; Y?ld?z, Pinar; Bedirhan, Mehmet Ali

2012-01-01

14

Video: argon plasma coagulator in a 2-month-old child with tracheoesophageal fistula.  

PubMed

A 2 month-old boy was admitted to the authors' hospital because of regurgitation and persistent cough during breastfeeding. A chest X-ray examination and a barium esophagogram disclosed small amounts of barium passing in the trachea, suggesting a tracheoesophageal fistula (TEF). Bronchoscopy combined with upper gastrointestinal (GI) endoscopy performed with the patient under general anesthesia confirmed the fistula. The TEF was treated by injection of 1 ml Glubran 2 from the esophageal side. A nasogastric tube was placed for feedings, and 7 days later, a barium esophagogram showed a reduction of caliber but not complete closure of the TEF. Unsuccessful fistula obliteration with Glubran was attributed to technical difficulties in catheterization of the fistula orifice, mainly resulting from its close proximity to the upper esophageal sphincter and to its small caliber. Therefore, an argon plasma coagulator (APC) probe with a circumferentially oriented nozzle was used from the esophageal side as an alternative technique to fulgurate the residual fistula orifice (see video). A nasogastric tube was placed for feedings. Oral feeding was started 7 days later when a barium esophagogram confirmed complete fistula closure. At the 2-year follow-up visit, the boy was asymptomatic, and the barium esophagogram was negative. This report describes a case in which esophagoscopy gave a clear view of the fistula due to its direction from esophagus to trachea. Complete fistula obliteration was not obtained with Glubran. However, APC was successfully used to close the residual fistula orifice. The authors suggest that APC can be used as an alternative endoscopic technique to repair TEF when other techniques fail. PMID:22476825

Nardo, Giovanni Di; Oliva, Salvatore; Barbato, Maria; Aloi, Marina; Midulla, Fabio; Roggini, Mario; Valitutti, Francesco; Frediani, Simone; Cucchiara, Salvatore

2012-04-05

15

Safety and Efficacy of Argon Plasma Coagulation Trimming of Malpositioned and Migrated Biliary Metal Stents: A Controlled Study in the Porcine Model  

Microsoft Academic Search

BACKGROUND:Argon plasma coagulation (APC) has been used to trim uncovered Elgiloy® stents, but the extent of thermal damage and bile duct injury is not known. The goal of this study was to evaluate the safety and efficacy of APC for this application.METHODS:Eight Elgiloy® (covered and uncovered) and four nitinol stents were deployed in the bile duct at ERCP in 12

Yang K. Chen; Vaman Jakribettuu; Erik W. Springer; Raj J. Shah; Jeanine Penberthy; S. Russell Nash

2006-01-01

16

Comparison of argon plasma coagulation in management of upper gastrointestinal angiodysplasia and gastric antral vascular ectasia hemorrhage  

PubMed Central

Background Vascular ectasias, including gastric antral vascular ectasia (GAVE) and angiodysplasia, are increasingly recognized as important sources of gastrointestinal bleeding. This study investigated and compared the efficacies and outcomes of treatment of upper gastrointestinal (UGI) angiodysplasia and GAVE hemorrhage by endoscopic argon plasma coagulation (APC). Methods From January 2006 to December 2009, 46 patients diagnosed with upper GI bleeding caused by angiodysplasia or GAVE at a tertiary hospital were recruited into this study. They included 26 males and 20 females with an average age of 65.6?years (range, 45–90?years). All patients underwent APC for hemostasis during an endoscopic procedure. Parameters such as underlying co-morbidities, number of endoscopic treatment sessions, recurrent bleeding, and clinical outcomes during follow-up were analyzed. Results The 46 patients with UGI vascular ectasia hemorrhage included 27 patients with angiodysplasia and 19 with GAVE. The patients with angiodysplasia were older than those with GAVE (71.6?±?10.2?years versus 61.8?±?11.9?years, P?=?0.005). More GAVE patients than angiodysplasia patients had co-existing liver cirrhosis (63.2% versus 25.9%, P?=?0.012). The patients with GAVE had a higher rate of recurrent bleeding (78.9% versus 7.4%, P?

2012-01-01

17

Argon beam coagulation for post-tonsillectomy hemostasis  

Microsoft Academic Search

Objective: The study goal was to evaluate the effectiveness of argon beam coagulation (ABC) in the prevention of post-tonsillectomy hemorrhage. ABC provides monopolar coagulation by arcing ionized argon gas to the target tissue; it is not a laser. Methods: Two consecutive studies were performed as follows. In the first, a retrospective analysis of post-tonsillectomy bleeding in 344 patients was conducted.

David M. Bowling

2002-01-01

18

A randomised controlled trial of ablation of Barrett's oesophagus with multipolar electrocoagulation versus argon plasma coagulation in combination with acid suppression: long term results  

PubMed Central

Background Many modalities have been used to ablate Barrett's oesophagus (BO). However, long term results and comparative effectiveness are unknown. Aims Our aim was to compare the long term efficacy of achieving complete reversal (endoscopic and histological) between multipolar electrocoagulation (MPEC) and argon plasma coagulation (APC) in BO patients and assess factors influencing successful ablation. Methods Patients with BO, 2–6?cm long, underwent 24?hour pH testing on proton pump inhibitor (PPI) therapy. Patients were then randomised by BO length to undergo ablation with MPEC or APC every 4–8?weeks until endoscopic reversal or maximal of six treatment sessions. Results Thirty five BO patients have been followed for at least two years following endoscopic ablation, 16 treated with MPEC and 19 with APC. There was complete reversal of BO in 24 patients (69%); 75% with MPEC and 63% with APC (p?=?0.49). There was no difference in the number of sessions required in the two groups. There was no difference in age, pH results, BO length, PPI dose, or hiatal hernia size between patients with and without complete reversal. One patient developed an oesophageal stricture but there were no major complications such as bleeding or perforation. Conclusions In BO patients treated with MPEC or APC in combination with acid suppression, at long term follow up, complete reversal of BO can be maintained in approximately 70% of patients, irrespective of the technique. There are no predictors associated with achieving complete reversal of BO. Continued surveillance is still indicated in the post ablative setting. As yet, these techniques are not ready for clinical application (other than for high grade dysplasia or early oesophageal adenocarcinoma) and cannot be offered outside the research arena.

Sharma, P; Wani, S; Weston, A P; Bansal, A; Hall, M; Mathur, S; Prasad, A; Sampliner, R E

2006-01-01

19

Efficacy and one year follow up of argon plasma coagulation therapy for ablation of Barrett's oesophagus: factors determining persistence and recurrence of Barrett's epithelium  

PubMed Central

Introduction: Barrett’s epithelium (BE) has malignant potential. Neither acid suppression nor antireflux surgery produce consistent or complete regression of the metaplastic epithelium. Endoscopic thermoablation with argon plasma coagulation (APC) offers a different approach but factors influencing its outcome have not been systematically examined. Aim: To assess the efficacy of APC and factors influencing initial and one year outcome. Methods: Fifty patients, mean age 61.4 years, mean BE length 5.9 cm (range 3–19), underwent APC therapy at four weekly intervals while receiving proton pump inhibitor (PPI) therapy. BE margins were marked by India ink tattooing and extent was documented by grid drawings, photography, and 2 cm interval quadrantic jumbo biopsies. Twenty four hour ambulatory oesophageal pH studies were done while on PPIs before and after APC therapy, and Bilitec bilirubin monitoring after APC completion. Results: A total of 68% of patients achieved >90% BE ablation after a median of four APC sessions. Persistent BE (>10% original BE area) was associated with longer initial BE length despite more APC sessions. Persistent acid and bile reflux on PPIs, although commoner in this group, were not significantly different from those successfully ablated. Fifteen of 34 patients (44%) with successful macroscopic clearance had buried glands, present in 8.3% of a total of 338 biopsies. At the one year follow up, only 32% of those with initial successful ablation showed no recurrence. BE recurred or increased in most with mean segment length increases of 1.1 cm and 1.6 cm, respectively, in patients with previous full ablation and those with persistent BE. The presence of buried glands did not predict BE recurrence. Patients who reduced their PPI dose had significantly greater BE recurrence. Conclusions: APC is most effective for shorter segment BE ablation but “buried” glands do occur. Recurrence of BE is common at one year, especially in those with initial persistent and/or long segment BE and those who reduce their PPI dose.

Basu, K K; Pick, B; Bale, R; West, K P; de Caestecker, J S

2002-01-01

20

Adrenaline injection plus argon plasma coagulation versus adrenaline injection plus hemoclips for treating high-risk bleeding peptic ulcers: A prospective, randomized trial  

PubMed Central

BACKGROUND/OBJECTIVE: Several combination endoscopic therapies are currently in use. The present study aimed to compare argon plasma coagulation (APC) + adrenaline injection (AI) with hemoclips + AI for the treatment of high-risk bleeding peptic ulcers. METHODS: In a prospective randomized trial, 172 patients with major stigmata of peptic ulcer bleeding were randomly assigned to receive APC + AI (n=89) or hemoclips + AI (n=83). In the event of rebleeding, the initial modality was used again. Patients in whom treatment or retreatment was unsuccessful underwent emergency surgery. The primary end point of rebleeding rate and secondary end points of initial and definitive hemostasis need for surgery and mortality were compared between the two groups. RESULTS: The two groups were similar in all background variables. Definitive hemostasis was achieved in 85 of 89 (95.5%) of the APC + AI and 82 of 83 (98.8%) of the hemoclips + AI group (P=0.206). The mean volume of adrenaline injected in the two groups was equal (20.7 mL; P=0.996). There was no significant difference in terms of initial hemostasis (96.6% versus 98.8%; P=0.337), rate of rebleeding (11.2% versus 4.8%; P=0.124), need for surgery (4.5% versus 1.2%; P=0.266) and mortality (2.2% versus 1.2%; P=0.526). When compared for the combined end point of mortality plus rebleeding and the need for surgery, there was an advantage for the hemoclip group (6% versus 15.7%, P=0.042). CONCLUSION: Hemoclips + AI has no superiority over APC + AI in treating patients with high-risk bleeding peptic ulcers. Hemoclips + AI may be superior when a combination of all negative outcomes is considered.

Taghavi, Seyed Alireza; Soleimani, Seyed Mohammad; Hosseini-Asl, Seyed Mohammad Kazem; Eshraghian, Ahad; Eghbali, Hajar; Dehghani, Seyed Mohsen; Ahmadpour, Bita; Saberifiroozi, Mehdi

2009-01-01

21

Transpupillary CW YAG laser coagulation. A comparison with argon green and krypton red lasers.  

PubMed

The authors have developed a CW YAG laser for transpupillary coagulation. The effects of CW YAG coagulation on the retina, retinal vessels, and fovea were compared with those produced by the krypton red and argon green lasers. To produce threshold coagulative lesions in monkeys and rabbits, we needed five to ten times more energy with the CW YAG than with the krypton red or argon green lasers. Nerve fiber damage was observed only when coagulating retinal vessels with the argon green laser. At the parameters used, none of the lasers damaged the sensory retina of the fovea. The CW YAG may be used as a new mode of laser coagulation in the treatment of retinal diseases. PMID:6688868

Peyman, G A; Conway, M D; House, B

1983-08-01

22

Temperature behaviour of a model port-wine stain during argon laser coagulation.  

PubMed

Temperature calculations on a model of a port-wine stain during argon laser coagulation have been performed. The model consists of four plane parallel layers representing the epidermis, the upper dermis, the superficial capillary blood plexus, and the deeper dermis. The light distribution inside the skin is calculated on the basis of the Kubelka-Munk theory. The numerical calculations have been performed by an 'alternating-direction-implicit' finite difference method. For the usual combination of exposure time and beam radius of the argon laser (between 0.1 and 0.6 s, and 0.5 mm or 1 mm) the shortest exposure time and largest beam radius yields the most efficient plexus coagulation. The model confirms that plexus coagulation implies destruction of epidermis and stratum papillare. Heat summation effects at the laser spot boundaries can be avoided when a distance of 2.5 times the beam radius is used between adjacent spots (centre-to-centre). An optimal argon laser treatment technique is suggested yielding full plexus coagulation with minimal or no scarring. Two simple physical requirements are given for the ideal laser to coagulate port-wine stains in an efficient and selective manner, suggesting application of pulsed dye lasers, emitting either at 418 nm or at 577 nm. PMID:6890212

van Gemert, M J; de Kleijn, W J; Henning, J P

1982-09-01

23

Modelling of an argon plasma flow  

Microsoft Academic Search

One-fluid MHD equations are numerically solved for an axisymmetric flow of argon inside and outside a discharge chamber of a cascaded plasma torch. Arc currents of 100 and 150 A, flow rates of 10 and 30 slpm, and two different optical thicknesses are assumed. The flow is shown to be only weakly compressible, of the Mach number below 0.3. The

Pavel Kotalík

2005-01-01

24

Diamond film growth argon-carbon plasmas  

DOEpatents

A method and system for manufacturing diamond film. The method involves forming a carbonaceous vapor, providing a gas stream of argon, hydrogen and hydrocarbon and combining the gas with the carbonaceous vapor, passing the combined carbonaceous vapor and gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the carbonaceous and deposition of a diamond film on a substrate.

Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (Naperville, IL); Liu, Shengzhong (Canton, MI); Pan, Xianzheng (Wuhan Hubei, CN); Zuiker, Christopher D. (LaGrange, IL)

1998-01-01

25

Zinc ionization by interaction with argon plasma  

Microsoft Academic Search

A low-temperature zinc plasma was generated by secondary ionization using an electron cyclotron resonance argon plasma. The ionization efficiency of zinc samples of the metal, the bromide, and the iodide were examined at different sample crucible temperatures. It was found that the ionization rate of zinc metal is the highest among the tested samples. The observed reaction rate constants icons\\/Journals\\/Common\\/alpha\\

Yoko Kawai; Tatsuya Suzuki; Yasuhiko Fujii

1999-01-01

26

Measuring opacity of shock generated argon plasmas  

NASA Astrophysics Data System (ADS)

Plasmas are generated by passage of a strong planar shock wave through gas. Initial experiments in argon have produced plasmas with 2 eV temperature, 0.004 gm/cu cm density, and coupling parameter Gamma approximately 0.3 - 0.7. Plasmas having Gamma greater than 1 are attainable with greater initial gas pressure. The opacity of the plasma is measured versus wavelength by recording the risetime of emitted light. Initial measurements are in visible light. Preliminary results are compared with calculations using the HOPE code.

Erskine, D.; Rozsnyai, B.; Ross, M.

1992-09-01

27

Measuring opacity of shock generated argon plasmas  

NASA Astrophysics Data System (ADS)

Plasma are generated by passage of a strong planar shock wave through gas. Initial experiments in argon have produced plasmas with 2eV temperature, 0.004-0.04 g/cu cm density, and coupling parameter Gamma approx. 0.3-0.7. Plasmas having Gamma greater than 1 are attainable with greater initial gas pressure. The opacity of the plasma is measured versus wavelength by recording the risetime of emitted light. Initial measurements are in visible light. Preliminary results are compared with calculations using the HOPE code.

Erskine, David; Rozsnyai, Balazs; Ross, Marvin

1994-02-01

28

Merging of High Speed Argon Plasma Jets  

NASA Astrophysics Data System (ADS)

Formation of an imploding plasma liner for the Plasma Liner Experiment (PLX) requires individual plasma jets to merge into a uniform shell of plasma converging on the target region. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present here results from the study of the merging of six plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. one centimeter MiniRailguns using a preionized Argon plasma armature on a vacuum chamber designed to partially reproduce the port geometry of the PLX vacuum chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, and magnetic field. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

Case, Andrew; Messer, Sarah; Brockington, Sam; Wu, Lin-Chun; Witherspoon, F. Douglas

2012-10-01

29

Merging of high speed argon plasma jets  

NASA Astrophysics Data System (ADS)

Formation of an imploding plasma liner for the plasma liner experiment (PLX) requires individual plasma jets to merge into a quasi-spherical shell of plasma converging on the origin. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present results from the study of the merging of three plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. 1 cm Minirailguns with a preionized argon plasma armature. The vacuum chamber partially reproduces the port geometry of the PLX chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

Case, A.; Messer, S.; Brockington, S.; Wu, L.; Witherspoon, F. D.; Elton, R.

2013-01-01

30

Experiences with the use of an argon beam coagulator in reduction mammaplasty  

Microsoft Academic Search

Argon beam coagulation is a method that is steadily gaining popularity in plastic surgery procedures. In an attempt to judge\\u000a its true value, a prospective, randomized trial was performed in reduction mammaplasty. Fifty-six patients were studied; in\\u000a 28 the Valleylab Force GSU System was used and in 28 conventional electrocautery. Pre-, intra- and postoperative hemoglobin and hematocrit values for\\u000a the

W. G. N. Steinmetz; B. J. Bauer; P. Eckert

1998-01-01

31

Complete Surgical Cytoreduction of Advanced Ovarian Carcinoma Using the Argon Beam Coagulator  

Microsoft Academic Search

Objective.The aim of this study was to evaluate the utility of the argon beam coagulator (ABC) in achieving optimal (?1 cm) disease status and facilitating the conversion of optimal but visible disease (0.1–1.0 cm) to microscopic residual disease (complete cytoreduction) among patients with advanced ovarian carcinoma.Methods. All patients undergoing their primary attempt at surgical cytoreduction for Stage IIIB–IV epithelial ovarian

Robert E. Bristow; F. J. Montz

2001-01-01

32

Practical Usefulness of Ultrasonic Surgical Aspirator with Argon Beam Coagulation for Hepatic Parenchymal Transection  

Microsoft Academic Search

The objective of this study was to evaluate the effectiveness and feasibility of using the Cavitron ultrasonic surgical aspirator\\u000a (CUSA) with argon beam coagulation (ABC) during hepatic resection, in comparison with a conventional method using CUSA with\\u000a bipolar cautery. Between April 2003 and March 2004, a series of 14 consecutive patients underwent hepatic resection of normal\\u000a liver. Hepatectomies were performed

Yasuhiko Nagano; Kenichi Matsuo; Chikara Kunisaki; Hideyuki Ike; Toshio Imada; Kuniya Tanaka; Shinji Togo; Hiroshi Shimada

2005-01-01

33

Laparoscopic simple enucleation and coagulation on tumor bed using argon beam coagulator for treating small renal cell carcinomas: An animal study followed by clinical application  

PubMed Central

Summary Background The aim of our study was to evaluate the feasibility and clinical effect of laparoscopic simple enucleation and coagulation on tumor bed using an argon beam coagulator for treating small renal cell carcinomas. Material/Methods The animal experiments of coagulation therapy on the wound tissue bed during partial nephrectomy with an argon beam coagulator were performed on 16 rabbits, which were randomly divided into 4 groups. Groups A and B had renal artery occlusion; the treatment time of coagulation was 4 seconds and 6 seconds, respectively. Groups C and D did not have renal artery occlusion; the treatment time of coagulation was 2 seconds and 4 seconds, respectively. Then 30 clinical operations of laparoscopic simple enucleation and coagulation on tumor bed using an argon beam coagulator were performed. Results All 16 rabbits successfully underwent the operation. By the histological examination, the scab depth of the wound tissue bed in groups A, B, C, and D were 2.76±0.17 mm, 3.15±0.15 mm, 2.28±0.16 mm and 2.75±0.06 mm, respectively. Group A differed significantly from groups B and C (P=0.012, 0.007), and group D differed significantly from groups B and C (P=0.002, 0.002). In the clinical study, all 30 patients successfully underwent the operation. The mean operative time was 182 minutes, and the mean blood loss was 280 ml. With a median follow-up time of 37 months, neither local recurrence nor distant metastasis was found by computerized tomography scan. Conclusions Laparoscopic simple enucleation and coagulation on tumor bed using an argon beam coagulator can be considered for treating small renal cell carcinomas. However, the indication of this procedure should be highly selected.

Zhang, Changwen; Xu, Yong; Zhang, Zhihong; Qiao, Baomin; Yang, Kuo; Liu, Ranlu; Ma, Baojie

2012-01-01

34

Successful management of severe chylothorax with argon plasma fulguration and fibrin glue in a premature infant.  

PubMed

Post-traumatic neonatal chylothorax is a rare entity. Management includes medical and surgical treatment. We describe here a newborn who developed a severe chylothorax after repair of an oesophageal atresia. The chylothorax was treated successfully by a combination of argon beam coagulation of the mediastinum and fibrin glue application. However, the patient developed complete thrombosis of the left femoral vein with clot extension to the inferior vena cava which resolved after infusion of recombinant tissue plasminogen activator (rt-PA). The use of argon plasma coagulation and mediastinal fibrin glue application for treating postoperative chylothorax appears to be attractive and is easy to perform even in small premature infants and may replace a more extensive surgical procedure. However, the coagulation profile should be monitored and special care should be taken to prevent vascular thrombosis after surgery. PMID:14618523

Rifai, N; Sfeir, R; Rakza, T; Alameh, J; Besson, R; Lequien, P; Storme, L

2003-10-01

35

Diamond film growth argon-carbon plasmas  

DOEpatents

A method and system are disclosed for manufacturing diamond film. The method involves forming a carbonaceous vapor, providing a gas stream of argon, hydrogen and hydrocarbon and combining the gas with the carbonaceous vapor, passing the combined carbonaceous vapor and gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the carbonaceous and deposition of a diamond film on a substrate. 29 figs.

Gruen, D.M.; Krauss, A.R.; Liu, S.Z.; Pan, X.Z.; Zuiker, C.D.

1998-12-15

36

Nanoparticle-Plasma Interactions in Dusty Argon-Hydrogen Plasmas  

NASA Astrophysics Data System (ADS)

We studied the role of hydrogen in altering the plasma-nanoparticle interactions in low pressure dusty Ar-H2 plasma. Most dusty plasmas in which particles form through chemical nucleation, are multi-component plasmas containing hydrogen. As hydrogen's ionization potential is close to that of argon, both gases may be ionized. The presence of the light mass hydrogen ions has the potential to modify the plasma and plasma-nanoparticle interactions. We developed a global model for dusty argon-hydrogen plasma. For given absorbed power, nanoparticle density, pressure, and chamber size, we solved the power balance, plasma species balance, and particle current balance equations. We included a system of rate equations for important argon-hydrogen plasma chemical reactions and obtained electron energy distribution function (EEDF) using ZDPlasKin. A trace amount of H2 gas in Ar discharge causes Ar^+, ArH^+, and H3^+ to be the dominant ions. Their relative densities are dependent on chamber pressure, gas composition, and the nanoparticle density. Increase in H2 gas fraction reduces the plasma density. The presence of light ions reduces the average particle charge. Electron collisions with hydrogen and with the nanoparticles affect the EEDF shape. Overall, we find that the presence of H2 in the discharge significantly alters the plasma properties and the fundamental plasma-nanoparticle interactions. This work was supported by the US Dept. of Energy Plasma Science Center and DOE grant DE/SC-0002391.

Kortshagen, Uwe; Mamunuru, Meenakshi

2012-10-01

37

Contact Activation of Blood Plasma Coagulation  

PubMed Central

This opinion identifies inconsistencies in the generally-accepted surface biophysics involved in contact activation of blood-plasma coagulation, reviews recent experimental work aimed at resolving inconsistencies, and concludes that this standard paradigm requires substantial revision to accommodate new experimental observations. Foremost among these new findings is that surface-catalyzed conversion of the blood zymogen factor XII (FXII, Hageman factor) to the enzyme FXIIa ( FXII?surfaceFXIIa, a.k.a. autoactivation) is not specific for anionic surfaces, as proposed by the standard paradigm. Furthermore, it is found that surface activation is moderated by the protein composition of the fluid phase in which FXII autoactivation occurs by what appears to be a protein adsorption-competition effect. Both of these findings argue against the standard view that contact activation of plasma coagulation is potentiated by assembly of activation-complex proteins (FXII, FXI, prekallikrein, and high-molecular-weight kininogen) directly onto activating surfaces (procoagulants) through specific protein/surface interactions. These new findings supplement the observation that adsorption behavior of FXII and FXIIa is not remarkably different from a wide variety of other blood proteins surveyed. Similarity in adsorption properties further undermines the idea that FXII and/or FXIIa are distinguished from other blood proteins by unusual adsorption properties resulting in chemically-specific interactions with activating anionic surfaces.

Vogler, Erwin A.; Siedlecki, Christopher A.

2009-01-01

38

Role of electronic excitation on thermodynamic and transport properties of argon and argon-hydrogen plasmas  

SciTech Connect

Thermodynamic and electron transport properties of the argon and argon-hydrogen plasmas have been calculated under the local thermodynamic equilibrium conditions in temperature range of 10 000-40 000 K over the wide range of pressures. Electronic excitation affects strongly these properties especially at high pressures. The inclusion of electronically excited states (EES) in relevant partition function influences the internal contribution to frozen and total specific heat for argon and argon-hydrogen plasma and it has been observed that although the total specific heat of argon plasma is less than that of hydrogen plasma, yet its internal contribution is more. Compensation between different contributions to total specific heat (by including and neglecting EES) occurring in hydrogen plasmas at low pressures has not been observed in argon and argon-hydrogen plasmas. As electron transport properties strongly depend upon the degree of ionization, therefore larger relative errors are found for these properties with and without EES, and in contrast to hydrogen plasma there exist a dominance of electron-atom cross section at low temperatures and EES dominance at intermediate temperatures.

Singh, Kuldip; Singh, Gurpreet; Sharma, Rohit [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

2010-07-15

39

Mechanical properties of coagulated albumin and failure mechanisms of liver repaired with the use of an argon-beam coagulator with albumin.  

PubMed

Hemostasis in the traumatized liver has been achieved by thermally denaturing topically applied albumin. In this article, the mechanical properties of liver and denatured albumin (solder) were measured, and the failure methods of liver repaired with albumin were identified. The ultimate tensile strength and Young's modulus were measured for healthy liver (N = 20) and thermally damaged liver (N = 20). The ultimate tensile strength and Young's modulus were measured for three concentrations of coagulated albumin (25, 38, and 53%) in a single layer and for two layers of denatured 38% albumin. Failure under tension of argon-beam coagulator soldered liver on the parenchymal surface (N = 30) with 38% albumin in two layers had a 70% occurrence for tearing at a mean stress of 39 kPa and a 23% occurrence for shearing at a mean stress of 7 kPa. Liver repaired on the interior surface (N = 11) failed in tension by tearing (64%) at a mean stress of 34 kPa and by shearing (36%) at a mean stress of 6 kPa. Argon-beam coagulator soldering with 38% albumin took 6 s/cm(2) for two layers of solder and gave the best balance of usability, strength, and matching of mechanical properties with those of the liver. PMID:12418016

Moffitt, T P; Baker, D A; Kirkpatrick, S J; Prahl, S A

2002-01-01

40

ECR Plasma Sterilisation, Argon and Nitrogen Treated Plasma  

NASA Astrophysics Data System (ADS)

ECR type plasma system was built to produce plasma in axial direction. Plasma was initiated in a specially designed Nickel - Chrome cylindrical vacuum tube which is being driven through dielectric window by 2.45GHz commercial magnetron source. Tube is also surrounded by a coil driving 150ADC to generate approximately 875Gauss magnetic field at the center. Langmuir probe and ICCD for optical spectrometry were used to characterize internal parameters like electron density, electron temperature and different characteristics of the plasma. Bacillus Subtilis var nigar, bacillus Stearothermophilus, bacillus pumilus E601, Escherichia coli and staphylococcus aureus type bacteria were selected as a reference. Each is resistant for different actions while the Bacilus cereus is the most resistant bacteria for microwave interaction. This study presents the effect of system on used bacteria. Those are gram positive and gram negative bacteria that refers to structure of cell wall. The sterilization efficacy of Argon type ECR plasma was found to be over 99, 5% in Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis (vegetative cell), Bacillus cereus (vegetative cell), Bacillus pumilus and Escherichia coli. System response type is less than 2 minutes.

Helhel, Selcuk; Oksuz, Lutfi; Cerezci, Osman; Rad, Abbas Y.

2004-09-01

41

Behavior of Excited Argon Atoms in Inductively Driven Plasmas  

SciTech Connect

Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s{sub 5} and 1s{sub 4}, in inductively driven plasmas containing argon, chlorine and boron trichloride. The behavior of the two energy levels with plasma conditions was significantly different, probably because the 1s{sub 5} level is metastable and the 1s{sub 4} level is radiatively coupled to the ground state but is radiation trapped. The argon data is compared with a global model to identify the relative importance of processes such as electron collisional mixing and radiation trapping. The trends in the data suggest that both processes play a major role in determining the excited state density. At lower rfpower and pressure, excited state spatial distributions in pure argon were peaked in the center of the discharge, with an approximately Gaussian profile. However, for the highest rfpowers and pressures investigated, the spatial distributions tended to flatten in the center of the discharge while the density at the edge of the discharge was unaffected. The spatially resolved excited state density measurements were combined with previous line integrated measurements in the same discharge geometry to derive spatially resolved, absolute densities of the 1s{sub 5} and 1s{sub 4} argon excited states and gas temperature spatial distributions. Fluorescence lifetime was a strong fi.mction of the rf power, pressure, argon fraction and spatial location. Increasing the power or pressure resulted in a factor of two decrease in the fluorescence lifetime while adding Cl{sub 2} or BCl{sub 3} increased the fluorescence lifetime. Excited state quenching rates are derived from the data. When Cl{sub 2} or BCl{sub 3} was added to the plasma, the maximum argon metastable density depended on the gas and ratio. When chlorine was added to the argon plasma, the spatial density profiles were independent of chlorine fraction. While it is energetically possible for argon excited states to dissociate some of the molecular species present in this discharge, it does not appear to be a significant source of dissociation. The major source of interaction between the argon and the molecular species BCl{sub 3} and Cl{sub 2} appears to be through modification of the electron density.

HEBNER,GREGORY A.; MILLER,PAUL A.

1999-12-07

42

Surface modification of polypropylene with an atmospheric pressure plasma jet sustained in argon and an argon\\/water vapour mixture  

Microsoft Academic Search

In this paper, an atmospheric pressure plasma jet sustained in pure argon and an argon\\/water vapour mixture has been used to modify the surface of polypropylene (PP) films. The gas temperature of the plasma jet was found to be 625K in an active zone between the electrodes and was found to increase in the afterglow. Based on these results, the

Abdollah Sarani; Anton Yu Nikiforov; Nathalie De Geyter; Rino Morent; Christophe Leys

2011-01-01

43

A CFD STUDY OF HYPERSONIC WEAKLY IONIZED ARGON PLASMA FLOW  

Microsoft Academic Search

A multiple- specie argon plasma flow with weak ionization at hypersonic speeds for the heavy particles is studied with a single- step time- dependent method. The charge separation that may occur behind the shock is based on the premises that while the heavy particle flow is supersonic, the electron flow is subsonic. Therefore, the charge separation should induce a strong

Tarit K. Bose

44

Characterization of SF(6)/Argon Plasmas for Microelectronics Applications.  

National Technical Information Service (NTIS)

This report documents measurements in inductively driven plasmas containing SF(sub 6)/Argon gas mixtures. The data in this report is presented in a series of appendices with a minimum of interpretation. During the course of this work we investigated: the ...

G. A. Hebner I. C. Abraham J. R. Woodworth

2002-01-01

45

Coagulation of charged particles in a dusty plasma  

Microsoft Academic Search

An investigation is made of characteristic features in the behavior of small particles in a dusty plasma attributable partly\\u000a to the suppression of coagulation as a result of monopolar charging for particle sizes smaller than the Debye shielding length\\u000a and partly to the reduction in the effect of charging for larger particles. Similarity relations linking the plasma composition\\u000a and particle

I. A. Belov; A. S. Ivanov; D. A. Ivanov; A. F. Pal’; A. N. Starostin; A. V. Filippov; A. V. Dem’yanov; Yu. V. Petrushevich

2000-01-01

46

Opacity measurements in shock-generated argon plasmas  

NASA Astrophysics Data System (ADS)

Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004-0.04 g/cu cm densities, and coupling parameters Gamma approximately equal to 0.3-0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

Erskine, D.

1993-07-01

47

Plasma study of a moly-oxide-argon discharge bulb  

Microsoft Academic Search

A mercury-free molybdenum-oxide-argon (Mo-O-Ar) electrodeless discharge is described with potential application to plasma lighting. The low-pressure metallic plasma is a nonequilibrium discharge capable of producing visible light directly with an efficacy of ?40 lm\\/W. The Boltzmann equation is solved with a limited set of chemical kinetics to provide a zero-dimensional model of the discharge. Model results indicate a transition in

John L. Giuliani; George M. Petrov; Robert E. Pechacek; Robert A. Meger

2003-01-01

48

Plasma discharge replacement for argon candles  

NASA Astrophysics Data System (ADS)

This paper reports on the progress made in developing a practical illumination system to replace argon candles. The basic concept--inexpensive, disposable, modular, surface discharge lamps that provide a flexible illumination geometry and which can be sized to match the impedance of the pulse forming network (PFN)--was described in the previous paper. Since then, the pulse shape and energy output have been measured for the complete system for the three different 19 kJ PFNs, having characteristics times of 70 microsecond(s) , 200 microsecond(s) , and 1 ms. Exposure tests confirmed that the illumination level is sufficient for color photography at 2 Mfps with a Cordin 330A and for 10 ns exposures with an IMACON 468. As the illumination source for plate fragmentation tests using live explosives, the system created `high quality images' and proved to be a useful tool that was easily integrated into the test procedure. The laboratory demonstration system has since been converted into a production model that has been installed in an instrumentation van at Eglin AFB to provide illumination at various ranges.

Root, Robert G.; Falkos, Paul

1999-05-01

49

Inhibition of activated coagulation factor VII by normal human plasma.  

PubMed

An amidolytic assay system with tissue thromboplastin (Tpl), purified coagulation factors VII and X, and the chromogenic substrate S-2222 was developed. Antithrombin III (AT) accounts for about one third of the total inhibition exerted by normal plasma in this test system. This effect of AT was prevented by adding purified AT blocking antibodies. Normal plasma and serum showed approximately similar inhibitory effects. The inhibition was probably directed against activated factor VII (F VIIa). Gel filtration of adsorbed normal plasma on Ultrogel AcA 34 showed three inhibitory peaks which were different from AT. PMID:7164015

Dahl, P E; Abildgaard, U; Larsen, M L; Tjensvoll, L

1982-12-27

50

Effect of helium on spatial plasma parameters in low pressure argon-helium plasma  

SciTech Connect

Spatial distributions of the electron energy probability function were measured using a Langmuir probe in side-type argon-helium inductively coupled plasma. Collisional dominated electron heating and a concave shape of plasma density profile were observed at 10 mTorr pure argon. As the helium proportion increased, the electron heating and density profile changed to collisionless dominated heating and a convex shape respectively, and the same tendency was shown when the pressure decreased in the pure argon plasma. These changes were due to the decrease in the e-n collision frequency and the expansion of the electron power dissipation region.

Bang, Jin-Young; Han, Duksun; Cho, Sung-Won; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2012-04-16

51

The influence of riboflavin photochemistry on plasma coagulation factors  

PubMed Central

Studies with riboflavin in the 1960s showed that it could be effective at inactivating pathogens when exposed to light. The principal mode of action is through electron transfer reactions, most importantly in nucleic acids. This suggested that it could act as a photosensitizer useful in the inactivation of pathogens found in blood products. Objective To study the influence of photo-inactivation with riboflavin on the coagulation factors of plasma. Methods The photo-inactivation procedure of riboflavin plus light was applied. Fifty isogroup pools of two plasmas were made from 100 U of plasma that were derived from whole blood products that had previously been held overnight. Pools were split into two bags. One of them was photo-inactivated, and post inactivation samples were obtained. The second bag was not photo-inactivated and samples were taken. Total protein, fibrinogen, FII, FV, FVII, FVIII, FIX, FX, FXI, FXIII, antithrombin III, PC, PS, ?-2 antiplasmin and vWF:Ag, the multimeric structure of vWF and ADAMTS-13 were analyzed. Results In plasma, the proteins most sensitive to photo-inactivation were fibrinogen, FXI, FVIII, FV, and FIX (33%, 32%, 30%, 18% and 18% loss, respectively). Coagulation inhibitors, PS, antithrombin III and PC showed little decrease (all 2%). Retention of vWF and ADAMTS-13 were 99% and 88%, respectively. Conclusions As with other pathogen reduction procedures for plasma products, treatment with riboflavin and UV light resulted in reduction in the activity levels of several pro-coagulant factors. Coagulation inhibitors are well preserved.

Larrea, Luis; Calabuig, Maria; Roldan, Vanesa; Rivera, Jose; Tsai, Han-Mou; Vicente, Vicente; Roig, Roberto

2011-01-01

52

Electrospray on superhydrophobic nozzles treated with argon and oxygen plasma  

NASA Astrophysics Data System (ADS)

We report on a simple process to fabricate electrohydrodynamic spraying devices with superhydrophobic nozzles. These devices are useful, among other things, in mass spectrometry and printing technology. The superhydrophobic nozzle is created by roughening the surface of the polyfluorotetraethylene (PTFE) by argon and oxygen plasma treatment. We have developed a polymer-based electrospray device with a flat, superhydrophobic nozzle capable of maintaining a high contact angle and stable jetting.

Byun, Doyoung; Lee, Youngjong; Tran, Si Bui Quang; Nugyen, Vu Dat; Kim, Sanghoon; Park, Baeho; Lee, Sukhan; Inamdar, Niraj; Bau, Haim H.

2008-03-01

53

Nanopillar ITO electrodes via argon plasma etching  

SciTech Connect

The authors demonstrate the formation of vertically aligned indium tin oxide (ITO) nanopillars by exposing planar ITO films to Ar plasma, the conditions of which determine the size, spacing, and aspect ratio of the pillars. Annealing in air and forming gas is used to recover and optimize the optical transmittance and electrical conductivity of the nanopillar films. The final product is an ITO film whose superior optical transmittance and strong electrical conductivity combine with its robust columnar morphology and processing scalability to make it suitable for use in highly absorbing organic solar cells.

Van Dijken, Jaron G.; Brett, Michael J. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada) and NRC-National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9 (Canada)

2012-07-15

54

Measurements of pulsed-power modulated argon plasmas in an inductively coupled plasma source  

Microsoft Academic Search

The behavior of pulsed-power (square wave) modulated argon plasmas generated by an inductively coupled plasma (ICP) source is experimentally investigated. The apparatus is an ICP source with a flat coil geometry equipped with a cylindrical Langmuir probe on the axis of the cylindrical chamber. The evolution of the plasma density is determined from the wave forms of ion saturation currents.

Sumio Ashida; M. R. Shim; M. A. Lieberman

1996-01-01

55

COAGULATION  

EPA Science Inventory

This chapter reports on the efforts of the USEPA to study conventional and enhanced coagulation for the control of disinfection by-products (DBPs) in drinking water. It examines the control of DBPs like trihalomethanes, haloacetic acids and the surrogate total organic halide in t...

56

Trimming of a Migrated Biliary Nitinol Stent Using Argon Plasma  

PubMed Central

Metallic stent migration is a well-known complication which cannot always be managed by removal or repositioning, especially in case of uncovered stent. We report a patient who developed obstructive jaundice due to migration of an expandable metallic stent (EMS) inserted in the lower bile duct. Trimming of the EMS using argon plasma was performed, with the power setting of 60 W and 2.0 l/min of argon flow. The distal part of the EMS was removed and mechanical cleaning using balloon catheter was performed for remnant EMS. Without additional stent insertion, jaundice was relieved in a few days. No complication was recognized during the procedure and no recurrence of jaundice in the rest of his life.

Matsubayashi, Hiroyuki; Hasuike, Noriaki; Tanaka, Masaki; Takizawa, Kohei; Yamaguchi, Yuichiro; Ono, Hiroyuki

2009-01-01

57

Atmospheric pressure argon plasma jet using a cylindrical piezoelectric transformer  

NASA Astrophysics Data System (ADS)

A low-voltage atmospheric pressure nonthermal argon plasma jet using a circular piezoelectric transducer is proposed. An Ar plasma flame is generated at an input voltage of 87 V. The consumed power is 2 W. The electrical and optical properties of the jet are analyzed. In particular, the transient Ar discharge ignition and evolution including the so-called plasma bullet phenomenon is examined temporally resolved with the aid of a fast camera. It is found that four discharge phases can be identified, designated as ignition, extension, self-propagation, and attenuation. The plasma bullet is launched while the electric field in the discharge space is decreasing. The average bullet velocity is 23 km/s.

Kim, Hyun; Brockhaus, Albrecht; Engemann, Jürgen

2009-11-01

58

Low Temperature Atmospheric Argon Plasma: Diagnostics and Medical Applications  

NASA Astrophysics Data System (ADS)

This study was devoted to diagnostic of low temperature plasma produced by microwave generator and investigation of its bactericidal effect against bacteria in biofilms and within eukaryotic cells. The profile of gas temperature near the torch outlet was measured. The spectrum in a wide range of wavelengths was derived by the method of optical emission spec-troscopy. Probe measurements of the floating potential of plasma were car-ried out. The estimation and adaptation of parameters of plasma flow (tem-perature, velocity, ion number density) according to medico-technical requirements were produced. The model of immersed surface-associated biofilms formed by Gram-negative bacteria, Pseudomonas aeruginosa and Burkholderia cenocepacia, and Gram-positive bacteria, Staphylococcus aureus, was used to assess bactericidal effects of plasma treatment. Reduction in the concentration of live bacteria in biofilms treated with plasma for 5 min was demonstrated by measuring Live/Dead fluorescent labeling and using direct plating. The intracellular infection model with the pathogenic bacterium, Chlamydia trachomatis, was used to study the efficacy of microwave argon plasma against intracellular parasites. A 2 min plasma treatment of mouse cells infected with C. trachomatis reduced infectious bacteria by a factor of 2×106. Plasma treatment diminished the number of viable host cells by about 20%. When the samples were covered with MgF2 glass to obstruct active particles and UV alone was applied, the bactericidal effect was re-duced by 5×104 fold compared to the whole plasma.

Ermolaeva, Svetlana; Petrov, Oleg; Zigangirova, Nailya; Vasiliev, Mikhail; Sysolyatina, Elena; Antipov, Sergei; Alyapyshev, Maxim; Kolkova, Natalia; Mukhachev, Andrei; Naroditsky, Boris; Shimizu, Tetsuji; Grigoriev, Anatoly; Morfill, Gregor; Fortov, Vladimir; Gintsburg, Alexander

59

The mechanism of radiative transfer in an argon and xenon plasma at a shock front  

Microsoft Academic Search

Experiments were conducted in a high-enthalphy shock tube to investigate radiation behind the shock front in argon at a Mach number of 16 and an initial pressure of 50 torr. Bright argon lines were observed on the background of the continuum, which is evidence for the transparence of the plasma; the self-absorption of the argon lines was also investigated. The

S. D. Savrov; I. M. Ageev; E. A. Dolgikh

1981-01-01

60

Observations of acoustic-wave-induced superluminescence in an argon plasma.  

PubMed

It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed. PMID:14611472

Aramyan, A R

2003-10-10

61

Transition radiation energy loss in inductively coupled argon plasma  

SciTech Connect

This work studies the transition radiation energy loss in inductively coupled argon plasma. Energy loss channels due to ionization, momentum transfer, and radiation are investigated in argon plasma bounded by a cylindrical metal vessel. Radiation energy is calculated using the electron energy distribution function diagnosed by a Langmuir probe and the emission cross section. The measured electron energy is found to feature a Druyvesteyn-like distribution. Detailed emission lines and their relative intensity are investigated using high resolution optical emission spectroscopy. Radiation energy loss due to the blue lines (mainly 5p{yields}4s transition) and red-IR lines (4p{yields}4s transition) appears less prominent than that of the two ultraviolet emission lines originated from the transitions of the two lowest resonant levels to the ground state. Approximately 30% collisional energy loss is responsible for ionization, whereas only a few percent of the energy loss is attributed to elastic collision. Most energy loss is due to the transition radiation emission. These findings are remarkably important for controllable plasma aided materials processing.

Ren Yuping; Long, J. D.; Xu, S. [Plasma Sources and Applications Center, NIE, and Institute of Advanced Studies, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

2007-07-15

62

Effect of the levitating microparticle cloud on radiofrequency argon plasma  

NASA Astrophysics Data System (ADS)

The effect of a levitating cloud of microparticles on the parameters of a radiofrequency (RF) plasma has been studied by means of two experimental techniques. Axial distributions of 1s excited states of argon were measured by a self-absorption method. A correction of a standard self-absorption method for the extinction of the light by the levitating microparticles is proposed. In addition the electron temperature was estimated using the optical emission spectroscopy. Measurements at the same discharge conditions in a microparticle-free discharge and discharge, containing a cloud of levitating microparticles, revealed the non-local influence of the microparticle cloud on the discharge plasma. The most probable cause of this influence is the disturbance of the ionization balance by the levitating microparticles.

Mitic, S.; Pustylnik, M. Y.; Klumov, B. A.; Morfill, G. E.

2010-06-01

63

Spectroscopic Characterization of Post-Cluster Argon Plasmas During the Blast Wave Expansion.  

National Technical Information Service (NTIS)

In this work we present temperature diagnostics of an expanding laser-produced argon plasma. A short-pulse (35fs) laser with an intensity of I= 10(sup 17)W/cm(sup 2) deposits(approx) 100 mJ of energy into argon clusters. This generates a hot plasma filame...

H. K. Chung K. B. Fournier M. J. Edwards H. A. Scott R. Cattolica T. Ditmire R. W. Lee

2002-01-01

64

Analytical Performance of Inductively Coupled Plasma Emission Spectrometry Using Argon-Nitrogen Binary and Argon-Helium-Nitrogen Ternary Gas Mixture System  

Microsoft Academic Search

Analytical performance of mixed gas inductively coupled plasmas (ICP) of argon-nitrogen binary and argon-helium- nitrogen ternary system was investigated for seven elements (Mg, Ca, Ba, Zn, Cd, Fe, and Y) having different ionization potentials, to yield the following. (1) In argon-nitrogen mixed gas ICPs, one should select higher flow rates of the carrier gas than in the argon ICP to

Kazuaki WAGATSUMA; Kichinosuke HIROKAWA

1994-01-01

65

Electrical and optical properties of high-pressure argon plasma  

SciTech Connect

Argon plasma has been investigated in the pressure range p greater than or equal to 200 bar and at temperatures up to 13,000 K. The experiments were performed by using a wall-stabilized arc in an uncooled copper cascade. The measured electrical conductivity agrees with theoretical predictions based on the unified theory. Line and continuous intensities, as well as width and shift of the Ar I line at lambda = 696.5 nm, were determined. A set of optimized atomic constants for these radiative processes was obtained by a newly developed multiple approximation method. While linewidth due to Stark and Van der Waals broadening are in fair agreement with theory, the line shift has to be corrected.

Poisel, H.; Landers, F.J.; Hoss, P.; Bauder, U.H.

1986-08-01

66

Sterilization of bacterial endospores by an atmospheric-pressure argon plasma jet  

SciTech Connect

Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. However, the spore-killing efficiency of the atmospheric-pressure argon-oxygen jet depends very sensitively on the oxygen concentration in the argon gas.

Uhm, Han S.; Lim, Jin P.; Li, Shou Z. [Department of Molecular Science and Technology, Ajou University, San 5 Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of); State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Department of Physics, Dalian University of Technology, Dalian 116024 (China)

2007-06-25

67

Argon plasma modeling with detailed fine-structure cross sections  

SciTech Connect

Our recently reported fully relativistic distorted-wave electron-impact cross sections from the ground and metastable states of argon to various excited fine-structure levels are incorporated in a collisional-radiative model to obtain the population densities for the 3p{sup 5}4s and 3p{sup 5}4p (1s and 2p) fine-structure manifolds for low temperature argon plasmas. Excitation cross sections from the two 3p{sup 5}4s J = 1 resonance levels, 1s{sub 2} and 1s{sub 4}, to the higher lying 2p fine-structure manifold as well as for transitions among individual levels of the 1s and 2p manifolds are also calculated and included in the present model which were not fully considered in any earlier model. Our results for the population densities of the 1s and 2p levels show good agreement with recent measurements. The variation of population densities of all the 1s and 2p levels with electron temperature and density are presented. We have also calculated and compared the intensities for the 750.38 nm (2p{sub 1}{yields} 1s{sub 2}) and 696.54 nm (2p{sub 2}{yields} 1s{sub 5}) lines with recently reported experimental results. The present work suggests that the inclusion of a complete fine-structure description of the electronic processes occurring in the plasma is important for a collisional radiative model, which includes separate 1s and 2p levels.

Gangwar, R. K.; Sharma, L.; Srivastava, R. [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Stauffer, A. D. [Department of Physics and Astronomy, York University, Toronto M3J 1P3 (Canada)

2012-03-01

68

Scope of plasma focus with argon as a soft X-ray source  

Microsoft Academic Search

The X-radiation emission from a low energy plasma focus with argon as a filling gas is investigated. Specifically, the attention is paid to determine the system efficiency for argon K-lines and Cu-K? line emission at different filling pressures, and identify the radiation emission region. The highest argon line emission found at 1.5 mbar is about 30 mJ and the corresponding

M. Zakaullah; K. Alamgir; M. Shafiq; M. Sharif; A. Waheed

2002-01-01

69

Rf-assisted magnetohydrodynamic power generation in a pure-argon plasma  

SciTech Connect

We describe seed-free pure-argon-plasma magnetohydrodynamic (MHD) power generation assisted by an external radio-frequency electromagnetic field to enhance the nonequilibrium plasma excitation process. The rf heating induces nonequilibrium ionization under a low total argon-gas temperature at which thermal ionization is insufficient. The rf-assisted plasma, the behavior of which is rather stable, contributes to continuous MHD energy conversion.

Murakami, Tomoyuki; Okuno, Yoshihiro; Yamasaki, Hiroyuki [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2005-04-25

70

Rf-assisted magnetohydrodynamic power generation in a pure-argon plasma  

NASA Astrophysics Data System (ADS)

We describe seed-free pure-argon-plasma magnetohydrodynamic (MHD) power generation assisted by an external radio-frequency electromagnetic field to enhance the nonequilibrium plasma excitation process. The rf heating induces nonequilibrium ionization under a low total argon-gas temperature at which thermal ionization is insufficient. The rf-assisted plasma, the behavior of which is rather stable, contributes to continuous MHD energy conversion.

Murakami, Tomoyuki; Okuno, Yoshihiro; Yamasaki, Hiroyuki

2005-04-01

71

Rf-assisted magnetohydrodynamic power generation in a pure-argon plasma  

Microsoft Academic Search

We describe seed-free pure-argon-plasma magnetohydrodynamic (MHD) power generation assisted by an external radio-frequency electromagnetic field to enhance the nonequilibrium plasma excitation process. The rf heating induces nonequilibrium ionization under a low total argon-gas temperature at which thermal ionization is insufficient. The rf-assisted plasma, the behavior of which is rather stable, contributes to continuous MHD energy conversion.

Tomoyuki Murakami; Yoshihiro Okuno; Hiroyuki Yamasaki

2005-01-01

72

Filamentation in argon microwave plasma at atmospheric pressure  

SciTech Connect

Filamentation in an argon plasma is studied using a microwave cavity at atmospheric pressure. We show that the size and gas temperature of the filaments increase with the power absorbed by the plasma. The appearance of an additional filament occurs at specific values of the absorbed power. Each new filament appears with a smaller diameter than that of its parent filament but the sum of the diameters of all filaments evolves linearly with the absorbed power. A secondary filament emerges from a set of microfilaments created by a perturbation of the electric field (a slight increase in the incident power above a threshold value). This perturbation occurs over a larger radius than that of the parent filament. By resorting to modeling, we found that the filamentation process involves either a decrease in the effective frequency for momentum-transfer collisions, i.e., a lower electron temperature, or an increase in the electron density. We could show that a small change in the relative positions occupied by two filaments in the microwave cavity requires a strong variation in the electron temperature.

Cardoso, R. P.; Belmonte, T.; Noeel, C.; Kosior, F.; Henrion, G. [Departement CP2S, CNRS, Institut Jean Lamour, Nancy-Universite, UPV-Metz, Parc de Saurupt, CS 14234, 54042 Nancy Cedex (France)

2009-05-01

73

Room-temperature atmospheric argon plasma jet sustained with submicrosecond high-voltage pulses  

NASA Astrophysics Data System (ADS)

In this letter, an experimental study is presented to characterize a room-temperature plasma jet in atmospheric argon generated with submicrosecond voltage pulses at 4 kHz. Distinct from sinusoidally produced argon discharges that are prone to thermal runaway instabilities, the pulsed atmospheric argon plasma jet is stable and cold with an electron density 3.9 times greater than that in a comparable sinusoidal jet. Its optical emission is also much stronger. Electrical measurement suggests that the discharge event is preceded with a prebreakdown phase and its plasma stability is facilitated by the short voltage pulses.

Walsh, J. L.; Kong, M. G.

2007-11-01

74

Neutral depletion and ion acceleration in an argon helicon plasma  

NASA Astrophysics Data System (ADS)

The effects of neutral depletion in an argon helicon plasma are investigated. High radiofrequency (RF) power is used (up to 3 kW) to produce helicon plasmas in a static magnetic field that can be configured in a flat or nozzle profile, with magnetic field strengths up to 1.04 kG in the antenna source region with a 1.5 kG nozzle peak. Microwave (105 GHz) interferometry is used to determine the line-averaged electron density (ne). The comparison of excited state populations of Ar I and Ar II with two different collisional-radiative (CR) models provides a non-invasive technique to measure the line-averaged electron temperature (Te) and neutral density (nn). Te is determined using the Atomic Data and Analysis Structure CR model, while n n is determined using a CR model originally developed by J. Vlcek. Measurement of the strong 488 nm Ar II line provides an indication of the plasma density np where interferometer access is limited. The axial ion velocity and temperature is measured through tunable diode laser-induced fluorescence (LIF). Observations indicate a collisional region of weak neutral depletion upstream of the antenna where increasing RF power leads to increased electron density (up to ne = 1.6 x 1013 cm-3) while Te remains essentially constant and low (1.7 to 2.0 eV). The collisionless downstream region exhibits profound neutral depletion (maximum 92% line-averaged ionization), where Te rises linearly with increasing RF power (4.9 eV at 3 kW) and ne remains constrained (below 6.5 x 1012 cm-3). The closed upstream region exhibits a uniform pressure profile along the axis of the experiment, indicating a pressure balance between the plasma source and a weakly-ionized region dominated by neutral particles. In contrast, a pressure gradient is observed in the downstream region extending to the downstream turbopump. The spatial extent of the pressure gradient region extends farther upstream as depletion levels rise. Plasma flow is accelerated (up to Mach 0.24) due to an axial pressure gradient with reduced collisional drag from neutral depletion. An inverse relationship between the axial ion velocity and the gas flow rate is observed through LIF.

Denning, C. Mark

75

Plating and Plating Solution Analysis by Inductively Coupled Argon Plasma Spectrometer: Final Report.  

National Technical Information Service (NTIS)

Plating solutions containing rhodium, gold, copper, tin, and zinc were analyzed for major constituents and trace impurities. Results of synthetic and real baths analyzed by an inductively coupled argon plasma spectrometer (ICAP) were compared to results o...

H. Reimer

1987-01-01

76

Electron Temperature Measurement of Argon Focussed Plasma Based on Non-local Thermodynamic Equilibrium Model  

NASA Astrophysics Data System (ADS)

The expected emission spectra (full, Bremsstrahlung, recombination, and line) of argon focussed plasma have been studied for different conditions. The Ratio-BPX65.F code has been written in FORTRAN 77 for studying the soft X-ray emission of argon plasma using BPX65 PIN Diode X-ray Spectrometer technique. The X-ray ratio curves for various electron temperatures with probable electron and ion densities of the argon plasma produced have been computed with the assumption of non-LTE model for the distribution of the ionic species. The calculated X-ray ratio curves have been compared with experimental results and an estimate of the electron temperature of the argon plasma focus can be deduced.

Akel, M.; Alsheikh Salo, S.; Wong, C. S.

2013-06-01

77

Diode Laser Based LIF Diagnostics for Argon and Helium Plasmas.  

NASA Astrophysics Data System (ADS)

A diode laser based Laser Induced Fluorescence (LIF) diagnostic that uses an inexpensive diode laser system is presented. The same diode laser is used to pump Ar II and He I transitions to obtain the ion and the neutral temperature of the respective species. The 1 MHz bandwidth diode laser has a Littrow external cavity with a mode-hop free tuning range up to 15 GHz and with a total power output of about 10 mWatt. The wavelength is measured by a wavemeter and frequent monitoring prevent wavelength drift. For the argon ion population, the laser tuned at 668.61 nm, is used to pump the 3d4F7/2 Ar II metastable level to the 4p4D5/2 excited level. The fluorescence radiation between the 4p4D5/2 and the 4s4P3/2 levels (442.6 nm) is monitored by a photomultiplier detector. For neutral helium, the laser is tuned at 667.82 nm to pump a fraction of the electron population from the 21P state to the 31D upper level. Although the 21P level is not a metastable state, the close proximity of 21S metastable level makes this new He I LIF possible in collisional plasmas. Some electrons of this 31D level undergo collisional excitation transfer (optically allowed transition) to the 31P. In turn, this state decay to the metastable 21S by emitting 501.6 nm fluorescence photons. The new LIF diagnostic has been developed at West Virginia University (WVU) and tested on the Hot hELIcon eXperiment (HELIX) plasma device. Ion and neutral temperatures obtained using this new LIF diagnostic are presented and compared to previous measurements performed with a more expensive and elaborate ring dye laser system.

Stolzenberg, E.; Boivin, R. F.; Compton, C.; Hardin, R.; Keesee, A.; Kline, J. L.; Scime, E. E.

2002-11-01

78

Stability conditions of argon and helium gas mixtures in an atmospheric pressure plasma jet  

Microsoft Academic Search

Non-equilibrium plasmas can be generated by atmospheric pressure glow discharges, amongst others by atmospheric pressure plasma jets (APPJ), which feature a capacitive radio-frequency discharge between bare metallic electrodes.We investigated the stability conditions for discharges in an APPJ operated with helium–argon mixtures. Uniform ?-discharges can be sustained in mixtures ranging from pure helium to pure argon. The ignition voltage increases drastically

S. Haslinger; J. Laimer; H. Störi

2007-01-01

79

Heat transfer between tungsten surface and glow discharge plasmas in argon and CO2  

NASA Astrophysics Data System (ADS)

A hot-filament method is used to study the heat transfer between tungsten surface and hollow-cathode glow discharge plasmas in argon and CO2. The dependence of the electric power supplied to a tungsten wire on the discharge current is determined for argon and carbon dioxide in the temperature range between 1000 and 1700 K. A difference in heat transfer at the tungsten wire surface is found between experiments on argon and carbon dioxide. The difference is attributed to heterogeneous recombination in CO2 plasma.

Polikarpov, F. D.; Polikarpov, A. F.; Borisov, S. F.; Nikulin, S. P.; Tretnikov, P. V.

2009-10-01

80

Fetal plasma contains coagulation factor XIIIa inhibitor absent in normal human plasma  

Microsoft Academic Search

A protein inhibitor of fibrin-stabilizing coagulation factor XIII was isolated from fetal human plasma. The inhibitor is absent\\u000a in newborns and adults. The purified protein is a 67-kD single-chain immunoglobulin; factor XIIIa activity in inhibited by\\u000a 80% with 100 ?l fetal plasma (16–22 weeks gestation) and by 100% with pure inhibitor (0.2 mg\\/ml). The persistence of this\\u000a inhibitor and low

I. S. Kolotushkina; Yu. A. Blidchenko; G. T. Sukhikh

1999-01-01

81

Calculations and measurements of argon emission in a magnetized linear plasma column  

NASA Astrophysics Data System (ADS)

Performing spectroscopic measurements of emission lines in relatively cold laboratory plasmas is challenging because the plasma is often neutral-dominated and is not in thermal equilibrium. However, these types of plasma do offer a unique opportunity for benchmarking the finer details of atomic physics codes. We report on new level-resolved calculations for the dielectronic recombination of low charge states of argon. The results are compared with existing configuration-average distorted-wave results and semi-empirical calculations. The recombination rates are processed into metastable-resolved recombination rate coefficients and used in non-equilibrium ionization balance modeling of an argon plasma experiment on the Auburn ALEXIS facility.

Arnold, Ivan; Ballance, Connor; Loch, Stuart; Thomas, Edward

2012-10-01

82

Properties of a capillary discharge-produced argon plasma waveguide for shorter wavelength source application.  

PubMed

We report the operation of a discharge-produced argon (Ar) plasma waveguide in an alumina (Al(2)O(3)) capillary to guide a 10(16)-W/cm(2) ultrashort laser pulse for shorter wavelength light sources at high repetition rate operation. The electron density in the plasma channel was measured to be 1 × 10(18) cm(-3). Modeling with a one-dimensional magnetrohydrodynamic code was used to evaluate the degree of ionization of Ar in the preformed plasma channel. The observed spectrum of the laser pulse after propagation in the argon plasma waveguide was not modified and was well reproduced by a particle in cell simulation. PMID:22047296

Sakai, Shohei; Higashiguchi, Takeshi; Bobrova, Nadezhda; Sasorov, Pavel; Miyazawa, Jun; Yugami, Noboru; Sentoku, Yasuhiko; Kodama, Ryosuke

2011-10-01

83

Comparative study of an argon plasma and an argon copper plasma produced by an ICP torch at atmospheric pressure based on spectroscopic methods  

NASA Astrophysics Data System (ADS)

The aim of the paper is to test the accuracy of classical spectroscopic methods in the visible domain dedicated to measurements of temperature and electron density in order to conclude about the validity of thermal disequilibrium. The influence of various factors is studied: accuracy of the intensity calibration, Abel inversion of the experimental spectra, excitation temperature deduced from the relative method, absolute excitation temperature, influence of the transition probability accuracy, influence of the Biberman factor value, electron temperature from the line-to-continuum intensity ratio, electron density deduced from Stark broadening, and electron density deduced from the continuum intensity. This spectroscopic investigation is carried out for argon plasma and argon copper plasma both produced by means of an ICP torch operating at atmospheric pressure. Results are given with uncertainties for each evaluated parameter. We show that, first, the electron temperature deduced from the line-to-continuum intensity ratio has to be considered with great care; second, for argon plasma no evidence of thermal disequilibrium can be discerned, whereas for argon copper plasma a small disequilibrium of 1.2 to 1.4 at most is experimentally observed.

Bussière, W.; Vacher, D.; Menecier, S.; André, P.

2011-08-01

84

Two distinct forms of Factor VIII coagulant protein in human plasma. Cleavage by thrombin, and differences in coagulant activity and association with von Willebrand factor.  

PubMed Central

We have characterized Factor VIII coagulant protein, present in normal human plasma, that reacts with a specific human 125I-labeled anti-human VIII:C antigen Fab antibody fragment. Two major Factor VIII coagulant antigen populations were present. The first, approximately 85% of the total antigen, was bound to von Willebrand factor and when tested in a standard one-stage assay had Factor VIII coagulant activity. The second antigenic population, eluting near fibrinogen when plasma was gel filtered, was not bound to von Willebrand protein, did not have Factor VIII coagulant activity unless activated, but did block anti-VIII:C Fab neutralization of clotting activity. The two antigenic populations were separable by cryoprecipitation and agarose gel electrophoresis. Although the two antigenic populations differed in their Factor VIII coagulant activity and in their binding to von Willebrand factor, the principal member of both populations is of mol wt 2.4 X 10(5). Both antigens, when proteolyzed by thrombin, were quickly converted to a 1 X 10(5)-mol wt form in association with the appearance of VIII:C activity. The 1 X 10(5)-mol wt antigen was further slowly degraded to an 8 X 10(4)-mol wt form while Factor VIII coagulant activity declined. These results demonstrate the presence of an inactive Factor VIII coagulant protein in plasma, not associated with von Willebrand factor, that can react with thrombin to yield Factor VIII coagulant activity. Images

Weinstein, M J; Chute, L E

1984-01-01

85

A pulse-modulated nonequilibrium atmospheric-pressure microwave argon plasma discharge preionized by a kilohertz excited plasma jet  

NASA Astrophysics Data System (ADS)

A pulse-modulated nonequilibrium atmospheric-pressure microwave argon surface wave plasma is generated by means of a preionization discharge with a single-electrode plasma jet driven by a power supply of 50 kHz. It is found that the electron induced Saha-like balance dominates excitation process in the plasma discharge through the electron temperature varying with the microwave input power and the applied voltage of kilohertz power supply. The microwave pulse-modulating effect on nonequilibrium characteristics of dual-frequency exciting argon surface wave plasma is studied by spectroscopic measurement of the excitation temperature and gas temperature.

Li, Shou-Zhe; Xu, Mao-Chun; Zhang, Xin; Zhang, Jialiang

2012-04-01

86

A pulse-modulated nonequilibrium atmospheric-pressure microwave argon plasma discharge preionized by a kilohertz excited plasma jet  

SciTech Connect

A pulse-modulated nonequilibrium atmospheric-pressure microwave argon surface wave plasma is generated by means of a preionization discharge with a single-electrode plasma jet driven by a power supply of 50 kHz. It is found that the electron induced Saha-like balance dominates excitation process in the plasma discharge through the electron temperature varying with the microwave input power and the applied voltage of kilohertz power supply. The microwave pulse-modulating effect on nonequilibrium characteristics of dual-frequency exciting argon surface wave plasma is studied by spectroscopic measurement of the excitation temperature and gas temperature.

Li Shouzhe; Xu Maochun; Zhang Xin; Zhang Jialiang [Key Laboratory of Materials Modification by Laser, Ion, Electron Beams, Ministry of Education, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2012-04-23

87

X-ray emission from PF1000 plasma-focus device admixtured with argon  

Microsoft Academic Search

Summary form only given. A new PF 1000 Mather-type plasma focus device with a 1.2 MJ capacitor bank, charging voltage U=45 kV, short circuit current I=15 MA, is now operated at IPPLM. The series of experiments with a hydrogen-argon mixture was performed within the energy range 250-450 kJ. The partial argon pressure was up to 20%. The hard and soft

M. Scholz; M. Borowiecki; L. Karpinski; R. Miklaszewski; W. Stepniewski; M. Sadowski; A. Szydlowski; V. M. Romanova; S. A. Pikuz; T. Ya. Faenov

1997-01-01

88

Characterization of an atmospheric double arc argon-nitrogen plasma source  

SciTech Connect

In the framework of studies devoted to hazardous waste destruction, an original dc double anode plasma torch has been designed and tested, which produces an elongated, weak fluctuation and reproducible plasma jet at atmospheric pressure. The arc instabilities and dynamic behavior of the double arc argon-nitrogen plasma jet are investigated through the oscillations of electrical signals by combined means of fast Fourier transform and Wigner distribution. In our experiment, the restrike mode is identified as the typical fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra and Wigner distributions exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which reveals that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the undulation of the power supply and both arc roots motion on the anode channels. In addition, the microscopic properties of the plasma jet inside and outside the arc chamber are investigated by means of optical emission spectroscopy, which yields excitation, electronic, rotational, and vibrational temperatures, as well as the electron number density. The results allow us to examine the validity criteria of a local thermodynamic equilibrium (LTE) state in the plasma arc. The measured electron densities are in good agreement with those calculated from the LTE model, which indicates that the atmospheric double arc argon-nitrogen plasma in the core region is close to the LTE state under our experimental conditions.

Tu, X. [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China); UMR 6614 CNRS CORIA, Saint Etienne du Rouvray 76801 (France); Cheron, B. G. [UMR 6614 CNRS CORIA, Saint Etienne du Rouvray 76801 (France); Yan, J. H.; Yu, L.; Cen, K. F. [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China)

2008-05-15

89

Non-equilibrium MHD power generation using non-seeded argon plasma  

Microsoft Academic Search

Experiments with a shock tunnel non-equilibrium MHD power generator using non-seeded argon plasma are described. A linear generator of constant cross section and a diverging generator of diverging cross section were used. Effects of J x B force on the plasma flow when large powers are extracted from the generator were observed. MHD power generator performance is described by the

M. Miyata; Y. Kawamura

1976-01-01

90

Droplet Striations Formed in a 900MHz Microwave Argon Atmospheric-Pressure Plasma Jet  

Microsoft Academic Search

Unique striations were observed in the formation of 900-MHz microwave argon atmospheric-pressure plasma jet in air. The striated patterns are easily observed even with the naked eyes at a flow rate of above 3 slm and an input power of below 3 W. Moreover, the striated patterns, which were associated with shortening in the plasma jet length, are obtained by

Sung Kil Kang; Abdel-Aleam H. Mohamed; Hyun Wook Lee; Jae Koo Lee

2011-01-01

91

Experimental characterization of an argon laminar plasma jet at atmospheric pressure  

NASA Astrophysics Data System (ADS)

This paper deals with a dc laminar pure argon plasma jet operating at atmospheric pressure in ambient air that was experimentally studied in order to obtain temperature and velocity. Plasma jet temperature was evaluated by optical emission spectroscopy and the plasma jet velocity was determined by various methods using a pressure sensor. It is shown that the maximum plasma jet temperature is 15 000 K and the maximum plasma jet velocity is 250 m s-1 at the plasma jet centre. Finally, a study of the ambient air amount entrained into the plasma jet is presented.

Langlois-Bertrand, Emilie; de Izarra, Charles

2011-10-01

92

Numerical simulation of alumina spraying in argon-helium plasma jet  

SciTech Connect

A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

Chang, C.H.

1992-01-01

93

Numerical simulation of alumina spraying in argon-helium plasma jet  

SciTech Connect

A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

Chang, C.H.

1992-08-01

94

Comparative Study of Plasma Parameters in Magnetic Pole Enhanced Inductively Coupled Argon Plasmas  

NASA Astrophysics Data System (ADS)

Langmuir probe measurements of radio frequency (RF) magnetic pole enhanced inductively coupled (MaPE-ICP) argon plasma were accomplished to obtain the electron number densities and electron temperatures. The measurements were carried out with a fixed RF frequency of 13.56 MHz in a pressure range of 7.5 mTorr to 75 mTorr at an applied RF power of 10 W and 100 W. These results are compared with a global (volume average) model. The results show good agreement between theoretical and experimental measurements. The electron number density shows an increasing trend with both RF power and pressure while the electron temperature shows decreasing trend as the pressure increases. The difference in the plasma potential and floating potential as a function of electron temperature measured from the electrical probe and that obtained theoretically shows a linear relation with a small difference in the coefficient of proportionality. The intensity of the emission line at 750.4 nm due to 2p1 ? 1s2 (Paschen's notation) transition closely follows the variation of ne with RF power and filling gas pressure. Measured electron energy probability function (EEPF) shows that electron occupation changes mostly in the high-energy tail, which highlights close similarity of 750.4 nm argon line to ne.

F., Jan; W. Khan, A.; Saeed, A.; Zakaullah, M.

2013-04-01

95

Measurement of plasma decay processes in mixture of sodium and argon by coherent microwave scattering  

SciTech Connect

This paper presents the experimental measurement and computational model of sodium plasma decay processes in mixture of sodium and argon by using radar resonance-enhanced multiphoton ionization (REMPI), coherent microwave Rayleigh scattering of REMPI. A single laser beam resonantly ionizes the sodium atoms by means of 2+1 REMPI process. The laser beam can only generate the ionization of the sodium atoms and have negligible ionization of argon. Coherent microwave scattering in situ measures the total electron number in the laser-induced plasma. Since the sodium ions decay by recombination with electrons, microwave scattering directly measures the plasma decay processes of the sodium ions. A theoretical plasma dynamic model, including REMPI of the sodium and electron avalanche ionization (EAI) of sodium and argon in the gas mixture, has been developed. It confirms that the EAI of argon is several orders of magnitude lower than the REMPI of sodium. The theoretical prediction made for the plasma decay process of sodium plasma in the mixture matches the experimental measurement.

Zhang Zhili [Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Shneider, Mikhail N. [Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2010-03-15

96

Sterilization of Bacillus subtilis Spores Using an Atmospheric Plasma Jet with Argon and Oxygen Mixture Gas  

NASA Astrophysics Data System (ADS)

To determine an efficient sterilization mechanism, Bacillus subtilis spore samples were exposed to an atmospheric plasma jet. By using argon/oxygen mixture gas, the decimal reduction value was reduced from 60 s (using argon gas) to 10 s. More dramatically, after 5 min treatment, the colony-forming unit (CFU) was reduced by six orders. To understand the underlying mechanism of the efficient sterilization by plasma, the contributions from heat, UV radiation, charged particles, ozone, and reactive oxygen radicals were distinguished in this work, showing that charged particles and ozone were the main killing factors. The shape changes of the spores were also discussed.

Shen, Jie; Cheng, Cheng; Fang, Shidong; Xie, Hongbing; Lan, Yan; Ni, Guohua; Meng, Yuedong; Luo, Jiarong; Wang, Xiangke

2012-03-01

97

Bacterial inactivation using a low-temperature atmospheric plasma brush sustained with argon gas.  

PubMed

This study investigated the bacterial inactivation/sterilization effects of a new atmospheric plasma source, which is a brush-shaped argon glow discharge created under 1 atm pressure. Such an atmospheric plasma brush requires extremely low power of less than 20 W to operate; and therefore is essentially a low-temperature discharge as confirmed by gas-phase temperature measurements. Two bacteria, Escherichia coli (E. coli) and Micrococcus luteus (M. luteus), seeded in various media were subjected to plasma treatment and their survivability was examined. It was found that such argon atmospheric plasma brush is very effective in destruction of the bacteria cells. With nutrient broth and standard methods agar as supporting media, a cell reduction in a level of 6 orders of magnitude was observed for E. coli within 3-4 min plasma treatment. A similar level of cell reduction was also observed for M. luteus in the two media with 2 or 3 min plasma treatment. The plasma treatment effects on the bacteria cell structures were also examined using scanning electron microscopy and the cell structure damages due to the plasma exposure were observed on both bacteria. The possible sterilization mechanism of the argon plasmas is also discussed in this article. PMID:16850477

Yu, Q S; Huang, C; Hsieh, F-H; Huff, H; Duan, Yixiang

2007-01-01

98

Correlation of Striated Discharge Patterns With Operating Conditions in Helium and Argon Atmospheric-Pressure Plasma Jets  

Microsoft Academic Search

This paper presents the evolution of striated dis- charge patterns in helium and argon atmospheric-pressure plasma jets as a function of gas flow rate and driving voltage. The striated patterns have been observed in helium and argon plasma jets at gas flow rates above 5 and 3 L\\/min, respectively. The striation pat- terns appear over the entire voltage range used

Young Sik Seo; Hyun Wook Lee; Abdel-Aleam H. Mohamed; Jae Koo Lee

2011-01-01

99

An Atmospheric-Pressure Helium Plasma Jet Induced by an Atmospheric-Pressure Argon Plasma Discharge in a Single-Electrode Configuration  

Microsoft Academic Search

An atmospheric-pressure (AP) cold helium plasma jet is induced by an argon plasma discharge generated in a single-electrode configuration at AP. The dependences of the length of the downstream and upstream helium plasma jets on the angle between gas flow directions of helium and argon, the applied voltage on the single electrode, and the gas flow rate of helium are

Shou-Zhe Li; Wen-Tong Huang; Dezhen Wang

2009-01-01

100

Surface modification of PTFE using an atmospheric pressure plasma jet in argon and argon + CO 2  

Microsoft Academic Search

Polytetrafluoroethylene (PTFE) has many successful engineering applications due to its great chemical stability. However, for some industrial applications, the poor adhesion of PTFE to other materials is a disadvantage. To extend the PTFE application range, several methods have been developed to modify its surface properties. Among these different techniques, plasma surface modification is the most promising one and therefore, an

A. Sarani; N. De Geyter; A. Yu. Nikiforov; R. Morent; C. Leys; J. Hubert; F. Reniers

101

Gas Temperature Determination in Argon-Helium Plasma at Atmospheric Pressure using van der Waals Broadening  

SciTech Connect

The use of the van der Waals broadening of Ar atomic lines to determine the gas temperature in Ar-He plasmas, taking into account both argon and helium atoms as perturbers, has been analyzed. The values of the gas temperature inferred from this broadening have been compared with those obtained from the spectra of the OH molecular species in the discharge.

Munoz, Jose; Yubero, Cristina; Calzada, Maria Dolores [Grupo de Espectroscopia de Plasmas, Edificio A. Einstein (C-2), Campus Rabanales, Universidad de Cordoba (Spain); Dimitrijevic, Milan S. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

2008-10-22

102

INDUCTIVELY COUPLED ARGON PLASMA AS AN ION SOURCE FOR MASS SPECTROMETRIC DETERMINATION OF TRACE ELEMENTS  

EPA Science Inventory

Solution aerosols are injected into an inductively coupled argon plasma (ICP) to generate a relatively high number density of positive ions derived from elemental constituents. A small fraction of these ions is extracted through a sampling orifice into a differentially pumped vac...

103

Physics of high-pressure helium and argon radio-frequency plasmas  

NASA Astrophysics Data System (ADS)

The physics of helium and argon rf discharges have been investigated in the pressure range from 50 to 760 Torr. The plasma source consists of metal electrodes that are perforated to allow the gas to flow through them. Current and voltage plots were obtained at different purity levels and it was found that trace impurities do not affect the shape of the curves. The electron temperature was calculated using an energy balance on the unbound electrons. It increased with decreasing pressure from 1.1 to 2.4 eV for helium and from 1.1 to 2.0 for argon. The plasma density calculated at a constant current density of 138 mA/cm2 ranged from 1.7×1011 to 9.3×1011 cm-3 for helium and from 2.5×1011 to 2.4×1012 cm-3 for argon, increasing with the pressure. At atmospheric pressure, the electron density of the argon plasma is 2.5 times that of the helium plasma.

Moravej, M.; Yang, X.; Nowling, G. R.; Chang, J. P.; Hicks, R. F.; Babayan, S. E.

2004-12-01

104

Properties of a capillary discharge-produced argon plasma waveguide for shorter wavelength source application  

SciTech Connect

We report the operation of a discharge-produced argon (Ar) plasma waveguide in an alumina (Al{sub 2}O{sub 3}) capillary to guide a 10{sup 16}-W/cm{sup 2} ultrashort laser pulse for shorter wavelength light sources at high repetition rate operation. The electron density in the plasma channel was measured to be 1 x 10{sup 18} cm{sup -3}. Modeling with a one-dimensional magnetrohydrodynamic code was used to evaluate the degree of ionization of Ar in the preformed plasma channel. The observed spectrum of the laser pulse after propagation in the argon plasma waveguide was not modified and was well reproduced by a particle in cell simulation.

Sakai, Shohei; Miyazawa, Jun [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Bobrova, Nadezhda; Sasorov, Pavel [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya str. 25, 117218 Moscow (Russian Federation); Sentoku, Yasuhiko [Department of Physics, University of Nevada, Mail Stop 220, Reno, Nevada 89506 (United States); Kodama, Ryosuke [Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2011-10-15

105

Purification of coagulation factor VIII using chromatographic methods. Direct chromatography of plasma in anion exchange resins.  

PubMed

Coagulation factor VIII (FVIII) concentrates are used in the treatment of patients with Hemophilia A. Human FVIII was purified directly from plasma using anion exchange chromatography followed by gel filtration. Three Q-Sepharose resins were tested, resulting in 40% recovery of FVIII activity using Q-Sepharose XL resin, about 80% using Q-Sepharose Fast Flow and 70% using the Q-Sepharose Big Beads. The vitamin K-dependent coagulation factors co-eluted with FVIII from the anion exchange columns. In the second step of purification, when Sepharose 6FF was used, 70% of FVIII activity was recovered free from vitamin K-dependent factors. PMID:20431912

Cheng, Elisabeth; Jinzenji, Daniela; Lorthiois, Ana Paula Almeida Aranha; de Carvalho, Roberta Rodrigues; Tanaka-Azevedo, Anita Mitiko; Raw, Isaías; Martins, Elizabeth Angélica Leme

2010-04-30

106

Study of Ar and Cu Plasma in a Magnetic Field Enhanced rf Argon Plasma for Ionized Sputtering of Cu  

NASA Astrophysics Data System (ADS)

One of the challenges for the manufacturing of ULSI integrated circuits is to deposit metal and alloy films into trenches with a high aspect ratio for vertical contact and interconnect purposes. As the device sizes are reduced to sub-0.25 micron regime, conventional sputtering deposition becomes insufficient. Recently, ionized sputtering has been studied to solve the aforementioned issues. In ionized sputtering, a high density RF argon plasma (densitys 10^11 to 10^12 ions per cm^3 ) is generated between the sputtering source and the substrate. The sputtered metal atoms become ionized when they travel through the high density RF plasma region. When a negative bias is applied to the stage, the positive metal ions will be attracted toward the wafer stage and become deposited on the substrate with good directionality. In this way, trenches with a high aspect ratio can be uniformly filled with metals. In this presentation, we will describe a prototype ionized sputtering system that utilizes a multipole magnetic field to enhance an inductively coupled rf argon plasma for ionization of Cu vapor. We will also report the Ar and Cu plasma properties as a function of Cu sputtering power by using Langmuir probe measurements in different argon pressures, as well as ionization trends for the sputtered Cu vapor in the argon plasma from optical emission spectroscopy.

Wang, W.; Foster, J.; Wendt, A.; Booske, J. H.; Gearhart, S. S.; Hershkowitz, N.

1997-10-01

107

Compact cryogenic source of periodic hydrogen and argon droplet beams for relativistic laser-plasma generation  

NASA Astrophysics Data System (ADS)

We present a cryogenic source of periodic streams of micrometer-sized hydrogen and argon droplets as ideal mass-limited target systems for fundamental intense laser-driven plasma applications. The highly compact design combined with a high temporal and spatial droplet stability makes our injector ideally suited for experiments using state-of-the-art high-power lasers in which a precise synchronization between the laser pulses and the droplets is mandatory. We show this by irradiating argon droplets with multi-terawatt pulses.

Fraga, R. A. Costa; Kalinin, A.; Kühnel, M.; Hochhaus, D. C.; Schottelius, A.; Polz, J.; Kaluza, M. C.; Neumayer, P.; Grisenti, R. E.

2012-02-01

108

Microparticle transport in an argon dc glow discharge dusty plasma due to an applied temperature gradient  

NASA Astrophysics Data System (ADS)

In recent years, increasing interest has focused on dust transport under microgravity plasma conditions. Earlier work studied dusty plasmas under reduced gravity conditions during sounding rocket flights [Morfill et al, Phys Rev Letters, 83, 1598 (1999)]. Ground-based experiments used temperature gradients in rf-generated complex plasmas to simulate reduced gravity conditions [Rothermel et al, Phys Rev Letters, 89, 175001 (2002)]. This presentation will discuss dust particle transport due to a thermophoretic force in an argon dc glow discharge plasma. Laser illumination and particle image velocimetry (PIV) are used to determine dust particle transport. Results of transport measurements are compared to a time dependant model for dust motion.

Engel, Patricia; Silver, Jennifer; Thomas, Edward

2004-11-01

109

High Speed Argon Plasma Jet Merging Studies In Support of PLX  

NASA Astrophysics Data System (ADS)

Formation of an imploding plasma liner for the Plasma Liner Experiment (PLX) requires individual plasma jets to merge into a uniform shell of plasma converging on the target region. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present here results from the study of the merging of two and three plasma jets in two dimensional (coplanar) and three dimensional geometry. The experiments were performed using HyperV Technologies Corp. one centimeter MiniRailguns using a preionized Argon plasma armature on a vacuum chamber designed to partially reproduce the port geometry of the PLX vacuum chamber. Diagnostics include fast imaging, spectroscopy, interferometry, deflectometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

Case, Andrew; Messer, Sarah; Brockington, Samuel; Wu, Lin Chun; Elton, Ray; Witherspoon, Douglas

2011-11-01

110

GASES, PLASMAS, AND ELECTRIC DISCHARGES: Arc Root Motions in an Argon Hydrogen Direct-Current Plasma Torch at Reduced Pressure  

NASA Astrophysics Data System (ADS)

Arc root motions in generating dc argon-hydrogen plasma as reduced pressure are optically observed using a high-spped video camera. The time resolved angular position of the arc root attachment point is measured and analysed. The arc root movement is characterized as a chaotic and jumping motion along the direction on the anode surface.

Huang, He-Ji; Pan, Wen-Xia; Wu, Cheng-Kang

2008-11-01

111

Physical and tribological properties of diamond films grown in argon-carbon plasmas  

SciTech Connect

Nanocrystalline diamond films have been deposited using a microwave plasma consisting of argon, 2--10% hydrogen and a carbon precursor such as C{sub 60} or CH{sub 4}. It was found that it is possible to grow the diamond phase with both carbon precursors, although the hydrogen concentration in the plasma was 1--2 orders of magnitude lower than normally required in the absence of the argon. Auger electron spectroscopy, x-ray diffraction measurements and transmission electron microscopy indicate the films are predominantly composed of diamond. Surface roughness, as determined by atomic force microscopy and scanning electron microscopy indicate the nanocrystalline films grown in low hydrogen content plasmas grow exceptionally smooth (30--50 nm) to thicknesses of 10 {mu}m. The smooth nanocrystalline films result in low friction coefficients ({mu}=0.04--0.06) and low average wear rates as determined by pin-on-disk measurements.

Zuiker, C.; Krauss, A.R.; Gruen, D.M.; Pan, X.; Li, J.C.; Csencsits, R.; Erdemir, A.; Bindal, C.; Fenske, G.

1995-06-01

112

Excited level populations and excitation kinetics of nonequilibrium ionizing argon discharge plasma of atmospheric pressure  

SciTech Connect

Population densities of excited states of argon atoms are theoretically examined for ionizing argon plasma in a state of nonequilibrium under atmospheric pressure from the viewpoint of elementary processes with collisional radiative model. The dependence of excited state populations on the electron and gas temperatures is discussed. Two electron density regimes are found, which are distinguished by the population and depopulation mechanisms for the excited states in problem. When the electron impact excitation frequency for the population or depopulation is lower than the atomic impact one, the electron density of the plasma is considered as low to estimate the population and depopulation processes. Some remarkable characteristics of population and depopulation mechanisms are found for the low electron density atmospheric plasma, where thermal relaxation by atomic collisions becomes the predominant process within the group of close-energy states in the ionizing plasma of atmospheric pressure, and the excitation temperature is almost the same as the gas temperature. In addition to the collisional relaxation by argon atoms, electron impact excitation from the ground state is also an essential population mechanism. The ratios of population density of the levels pairs, between which exists a large energy gap, include information on the electron collisional kinetics. For high electron density, the effect of atomic collisional relaxation becomes weak. For this case, the excitation mechanism is explained as electron impact ladderlike excitation similar to low-pressure ionizing plasma, since the electron collision becomes the dominant process for the population and depopulation kinetics.

Akatsuka, Hiroshi [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10, O-Okayama, Meguro-ku, Tokyo 152-8550 (Japan)

2009-04-15

113

Observations of neutral depletion and plasma acceleration in a flowing high-power argon helicon plasma  

SciTech Connect

Neutral depletion effects are observed in a steady-state flowing argon helicon plasma with a magnetic nozzle for high rf input powers (up to 3 kW). Noninvasive diagnostics including 105 GHz microwave interferometry and optical spectroscopy with collisional-radiative modeling are used to measure the electron density (n{sub e}), electron temperature (T{sub e}), and neutral density (n{sub n}). A region of weak neutral depletion is observed upstream of the antenna where increasing rf power leads to increased electron density (up to n{sub e}=1.6x10{sup 13} cm{sup -3}) while T{sub e} remains essentially constant and low (1.7-2.0 eV). The downstream region exhibits profound neutral depletion (maximum 92% line-averaged ionization), where T{sub e} rises linearly with increasing rf power (up to 4.9 eV) and n{sub e} remains constrained (below 6.5x10{sup 12} cm{sup -3}). Flux considerations indicate accelerated plasma flow (Mach 0.24) through the antenna region due to an axial pressure gradient with reduced collisional drag from neutral depletion.

Denning, C. Mark; Wiebold, Matt; Scharer, John E. [Electrical and Computer Engineering Department, University of Wisconsin-Madison, Engineering Research Building, 1500 Engineering Dr., Madison, Wisconsin 53704 (United States)

2008-07-15

114

Optimized H- extraction in an argon magnesium seeded magnetized sheet plasma  

NASA Astrophysics Data System (ADS)

The enhancement and optimization of H- extraction through argon and magnesium seeding of hydrogen discharges in a magnetized sheet plasma source are reported. The paper first presents the modification of the production chamber into a hexapole multicusp configuration resulting in decreased power requirements, improved plasma confinement and longer filament lifetime. By this, a wider choice of discharge currents for sustained quiescent plasmas is made possible. Second, the method of adding argon to the hydrogen plasma similar to the scheme in Abate and Ramos [Y. Abate, H. Ramos, Rev. Sci. Instr. 71 (10) (2000) 3689] was performed to find the optimum conditions for H- formation and extraction. Using an E × B probe, H- yields were investigated at varied argon hydrogen admixtures, different discharge currents and spatial points relative to the core plasma. The optimum H- current density extracted at 3.0 cm from the plasma core using 3.0 A plasma current with 10% argon seeding increased by a factor of 2.42 (0.63 A/m2) compared to the measurement of Abate and Ramos [Y. Abate, H. Ramos, Rev. Sci. Instr. 71 (10) (2000) 3689]. Third, the argon hydrogen plasma at the extraction chamber is seeded with magnesium. Mg disk with an effective area of 22 cm2 is placed at the extraction region’s anode biased 175 V with respect to the cathode. With Mg seeding, the optimum H- current density at the same site and discharge conditions increased by 4.9 times (3.09 A/m2). The enhancement effects were analyzed vis-à-vis information gathered from the usual Langmuir probe (electron temperature and density), electron energy distribution function (EEDF) and the ensuing dissociative attachment (DA) reaction rates at different spatial points for various plasma discharges and gas ratios. Investigations on the changes in the effective electron temperature and electron density indicate that the enhancement is due to increased density of low-energy electrons in the volume, conducive for DA reactions. With Mg, the density of electrons with electron temperature of about 3 eV increased 3 orders of magnitude from 2.76 × 1012 m-3 to 2.90 × 1015 m-3.

Noguera, Virginia R.; Blantocas, Gene Q.; Ramos, Henry J.

2008-06-01

115

Surface modification of ultra-high molecular weight polyethylene (UHMWPE) by argon plasma  

NASA Astrophysics Data System (ADS)

In this work, argon (Ar) plasma generated by microwave electron cyclotron resonance (MWECR) has been used to modify the UHMWPE in order to increase the wear resistance. The results showed that the wettability, anti-scratch and wear resistance of UHMWPE treated by the Ar plasma had been improved, comparing with native UHMWPE. The FTIR and XPS spectra indicated the improvement of wettability should come from the oxygen based functional groups generated on the surface of UHMWPE. The improvement of anti-scratch and wear resistance may come from the enhancement of crosslinking of UHMWPE by Ar plasma treatment.

Liu, Hengjun; Pei, Yanan; Xie, Dong; Deng, Xingrui; Leng, Y. X.; Jin, Yong; Huang, Nan

2010-04-01

116

Measurements and spectral modeling of neutral Argon as a diagnostic in the ALEXIS plasma  

NASA Astrophysics Data System (ADS)

We present spectral measurements and theoretical results for an argon plasma experiment on the ALEXIS (Auburn Linear Experiment for Instability Studies) device. Langmuir probe measurements for the electron temperature and density profiles along the line of sight were taken for a wide range of plasma B-field settings. Comparisons with theoretical models show that the plasma is not in ionization equilibrium. A theoretical spectrum is constructed using the line of sight profiles and recently calculated R-matrix atomic data. We also investigate the role of a non-equilibrium population in the neutral Ar metastable and how that affects the spectrum.

Kiene, Andrew; Loch, Stuart; Dubois, Ami; Eadon, Ashley; Thomas, Edward

2011-11-01

117

Comparison of functional aspects of the coagulation cascade in human and sea turtle plasmas.  

PubMed

Functional hemostatic pathways are critical for the survival of all vertebrates and have been evolving for more than 400 million years. The overwhelming majority of studies of hemostasis in vertebrates have focused on mammals with very sparse attention paid to reptiles. There have been virtually no studies of the coagulation pathway in sea turtles whose ancestors date back to the Jurassic period. Sea turtles are often exposed to rapidly altered environmental conditions during diving periods. This may reduce their blood pH during prolonged hypoxic dives. This report demonstrates that five species of turtles possess only one branch of the mammalian coagulation pathway, the extrinsic pathway. Mixing studies of turtle plasmas with human factor-deficient plasmas indicate that the intrinsic pathway factors VIII and IX are present in turtle plasma. These two factors may play a significant role in supporting the extrinsic pathway by feedback loops. The intrinsic factors, XI and XII are not detected which would account for the inability of reagents to induce coagulation via the intrinsic pathway in vitro. The analysis of two turtle factors, factor II (prothrombin) and factor X, demonstrates that they are antigenically/functionally similar to the corresponding human factors. The turtle coagulation pathway responds differentially to both pH and temperature relative to each turtle species and relative to human samples. The coagulation time (prothrombin time) increases as the temperature decreases between 37 and 15 degrees C. The increased time follows a linear relationship, with similar slopes for loggerhead, Kemps ridley and hawksbill turtles as well as for human samples. Leatherback turtle samples show a dramatic nonlinear increased time below 23 degrees C, and green turtle sample responses were similar but less dramatic. All samples also showed increased prothrombin times as the pH decreased from 7.8 to 6.4, except for three turtle species. The prothrombin times decreased, to varying extents, in a linear fashion relative to reduced pH with the rate of change greatest in leatherbacks>green>loggerhead turtles. All studies were conducted with reagents developed for human samples which would impact on the quantitative results with the turtle samples, but are not likely to alter the qualitative results. These comparative studies of the coagulation pathway in sea turtles and humans could enhance our knowledge of structure/function relationships and evolution of coagulation factors. PMID:15325341

Soslau, Gerald; Wallace, Bryan; Vicente, Catherine; Goldenberg, Seth J; Tupis, Todd; Spotila, James; George, Robert; Paladino, Frank; Whitaker, Brent; Violetta, Gary; Piedra, Rotney

2004-08-01

118

Surface-mediated molecular events in material-induced blood-plasma coagulation  

NASA Astrophysics Data System (ADS)

Coagulation and thrombosis persist as major impediments associated with the use of blood-contacting medical devices. We are investigating the molecular mechanism underlying material-induced blood-plasma coagulation focusing on the role of the surface as a step towards prospective development of improved hemocompatible biomaterials. A classic observation in hematology is that blood/blood-plasma in contact with clean glass surface clots faster than when in contact with many plastic surfaces. The traditional biochemical theory explaining the underlying molecular mechanism suggests that hydrophilic surfaces, like that of glass, are specific activators of the coagulation cascade because of the negatively-charged groups on the surface. Hydrophobic surfaces are poor procoagulants or essentially "benign" because they lack anionic groups. Further, these negatively-charged surfaces are believed to not only activate blood factor XII (FXII), the key protein in contact activation, but also play a cofactor role in the amplification and propagation reactions that ultimately lead to clot formation. In sharp contrast to the traditional theory, our investigations indicate a need for a paradigm shift in the proposed sequence of contact activation events to incorporate the role of protein adsorption at the material surfaces. These studies have lead to the central hypothesis for this work proposing that protein adsorption to hydrophobic surfaces attenuates the contact activation reactions so that poorly-adsorbent hydrophilic surfaces appear to be stronger procoagulants relative to hydrophobic surfaces. Our preliminary studies measuring the plasma coagulation response of activated FXII (FXIIa) on different model surfaces suggested that the material did not play a cofactor role in the processing of this enzyme dose through the coagulation pathway. Therefore, we focused our efforts on studying the mechanism of initial production of enzyme at the procoagulant surface. Calculations for the amounts of FXIIa generated at material surfaces in plasma using a mathematical model for measured coagulation responses indicate that the relative contributions of the individual pathways of enzyme generation are similar at both hydrophilic and hydrophobic surfaces, only the amounts of enzyme generated scale with surface energy and area of the activating surface. Further, from direct measurement of enzyme activation at test surfaces we observed that contact activation reactions are not specific to negatively-charged hydrophilic surfaces. Rather, the molecular interactions are attenuated at hydrophobic surfaces due to protein adsorption so that poorly-adsorbent hydrophilic surfaces exhibit an apparent specificity for contact activation reactions. Preliminary studies were preformed to assay the plasma coagulation response to low-fouling surfaces prepared by either grafting poly(ethylene glycol) chains or using zwitterions. Results indicate that poly(ethylene glycol)-modified surfaces are significantly weaker procoagulants than surfaces containing zwitterions underscoring a need to specifically evaluate the coagulation response despite similarities in observed protein adsorption to both surfaces. In summary, our studies demonstrate a need to incorporate protein-adsorption competition at procoagulant surfaces into the mechanism of contact activation to account for the observed moderation of FXII activation by blood proteins unrelated to the plasma coagulation cascade.

Chatterjee, Kaushik

119

Modeling of microwave-induced plasma in argon at atmospheric pressure.  

PubMed

A two-dimensional model of microwave-induced plasma (field frequency 2.45 GHz) in argon at atmospheric pressure is presented. The model describes in a self-consistent manner the gas flow and heat transfer, the in-coupling of the microwave energy into the plasma, and the reaction kinetics relevant to high-pressure argon plasma including the contribution of molecular ion species. The model provides the gas and electron temperature distributions, the electron, ion, and excited state number densities, and the power deposited into the plasma for given gas flow rate and temperature at the inlet, and input power of the incoming TEM microwave. For flow rate and absorbed microwave power typical for analytical applications (200-400 ml/min and 20 W), the plasma is far from thermodynamic equilibrium. The gas temperature reaches values above 2000 K in the plasma region, while the electron temperature is about 1 eV. The electron density reaches a maximum value of about 4 × 10(21) m(-3). The balance of the charged particles is essentially controlled by the kinetics of the molecular ions. For temperatures above 1200 K, quasineutrality of the plasma is provided by the atomic ions, and below 1200 K the molecular ion density exceeds the atomic ion density and a contraction of the discharge is observed. Comparison with experimental data is presented which demonstrates good quantitative and qualitative agreement. PMID:23004876

Baeva, M; Bösel, A; Ehlbeck, J; Loffhagen, D

2012-05-15

120

Surface Modification of Poly Vinyl Chloride (PVC) Using Low Pressure Argon and Oxygen Plasma  

NASA Astrophysics Data System (ADS)

In this study, commercial poly vinyl chloride (PVC) films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in the plasma reactor and also different exposure durations. Effects of the plasma treatment on the hydrophilic properties of the films were studied by measuring the water drop contact angle on the surface of the samples. The surface topography of the untreated and plasma treated films was analyzed and compared by atomic force microscopy (AFM). The optical characteristic changes in treated samples were investigated using reflective spectrophotometry. Also, the chemical changes which appeared on the surface of the samples were investigated using Fourier transform infrared spectroscopy (FTIR). The results show that the plasma treated PVC becomes more hydrophilic with an enhanced wettability. A sharp decrease in the water contact angle may also be a consequence of the surface texturization. The aging effect on wettability of the samples was also investigated. The results show that the effect of oxygen plasma on the surface properties of the samples is more pronounced compared with that of argon plasma.

Mahmood, Ghoranneviss; Sheila, Shahidi; Jakub, Wiener

2010-04-01

121

Investigation of capacitively coupled argon plasma driven at various frequencies and validation of surface waves excitation  

NASA Astrophysics Data System (ADS)

The influence of excitation frequency (13.56-96 MHz) on the characteristics of capacitively coupled argon plasma is investigated by means of Langmuir probe and a high-voltage probe. Measurements are performed in argon pressure of 40 and 60 mTorr at a fixed discharge voltage V=200 V. The measured electron energy distribution function EEPFs are a bi-Maxwellian type irrespective of the driving frequency and gas pressure. The electron density and temperatures show peak over frequency range of 54-72 MHz, beyond which it decreases. The non-monotonic dependences of plasma parameters with driving frequency were interpreted in terms of excited surface wave excited at the powered electrode.

Abdel-Fattah, E.

2013-01-01

122

Method to estimate the electron temperature and neutral density in a plasma from spectroscopic measurements using argon atom and ion collisional-radiative models  

SciTech Connect

We present a method to infer the electron temperature in argon plasmas using a collisional-radiative model for argon ions and measurements of electron density to interpret absolutely calibrated spectroscopic measurements of argon ion (Ar II) line intensities. The neutral density, and hence the degree of ionization of this plasma, can then be estimated using argon atom (Ar I) line intensities and a collisional-radiative model for argon atoms. This method has been tested for plasmas generated on two different devices at the University of Texas at Austin: the helicon experiment and the helimak experiment. We present results that show good correlation with other measurements in the plasma.

Sciamma, Ella M.; Bengtson, Roger D.; Rowan, W. L.; Lee, Charles A.; Berisford, Dan; Lee, Kevin; Gentle, K. W. [University of Texas at Austin, 1 University Station Austin, Texas 78712 (United States); Keesee, Amy [West Virginia University, P.O. Box 6315, Morgantown, West Virginia 26506 (United States)

2008-10-15

123

Measurement of factor v activity in human plasma using a microplate coagulation assay.  

PubMed

In response to injury, blood coagulation is activated and results in generation of the clotting protease, thrombin. Thrombin cleaves fibrinogen to fibrin which forms an insoluble clot that stops hemorrhage. Factor V (FV) in its activated form, FVa, is a critical cofactor for the protease FXa and accelerator of thrombin generation during fibrin clot formation as part of prothrombinase (1, 2). Manual FV assays have been described (3, 4), but they are time consuming and subjective. Automated FV assays have been reported (5-7), but the analyzer and reagents are expensive and generally provide only the clot time, not the rate and extent of fibrin formation. The microplate platform is preferred for measuring enzyme-catalyzed events because of convenience, time, cost, small volume, continuous monitoring, and high-throughput (8, 9). Microplate assays have been reported for clot lysis (10), platelet aggregation (11), and coagulation Factors (12), but not for FV activity in human plasma. The goal of the method was to develop a microplate assay that measures FV activity during fibrin formation in human plasma. This novel microplate method outlines a simple, inexpensive, and rapid assay of FV activity in human plasma. The assay utilizes a kinetic microplate reader to monitor the absorbance change at 405 nm during fibrin formation in human plasma (Figure 1) (13). The assay accurately measures the time, initial rate, and extent of fibrin clot formation. It requires only ?l quantities of plasma, is complete in 6 min, has high-throughput, is sensitive to 24-80 pM FV, and measures the amount of unintentionally activated (1-stage activity) and thrombin-activated FV (2-stage activity) to obtain a complete assessment of its total functional activity (2-stage activity - 1-stage activity). Disseminated intravascular coagulation (DIC) is an acquired coagulopathy that most often develops from pre-existing infections (14). DIC is associated with a poor prognosis and increases mortality above the pre-existing pathology (15). The assay was used to show that in 9 patients with DIC, the FV 1-stage, 2-stage, and total activities were decreased, on average, by 54%, 44%, and 42%, respectively, compared with normal pooled human reference plasma (NHP). The FV microplate assay is easily adaptable to measure the activity of any coagulation factor. This assay will increase our understanding of FV biochemistry through a more accurate and complete measurement of its activity in research and clinical settings. This information will positively impact healthcare environments through earlier diagnosis and development of more effective treatments for coagulation disorders, such as DIC. PMID:22987015

Tilley, Derek; Levit, Irina; Samis, John A

2012-09-09

124

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay  

PubMed Central

In response to injury, blood coagulation is activated and results in generation of the clotting protease, thrombin. Thrombin cleaves fibrinogen to fibrin which forms an insoluble clot that stops hemorrhage. Factor V (FV) in its activated form, FVa, is a critical cofactor for the protease FXa and accelerator of thrombin generation during fibrin clot formation as part of prothrombinase1, 2. Manual FV assays have been described 3, 4, but they are time consuming and subjective. Automated FV assays have been reported 5-7, but the analyzer and reagents are expensive and generally provide only the clot time, not the rate and extent of fibrin formation. The microplate platform is preferred for measuring enzyme-catalyzed events because of convenience, time, cost, small volume, continuous monitoring, and high-throughput 8, 9. Microplate assays have been reported for clot lysis 10, platelet aggregation 11, and coagulation Factors 12, but not for FV activity in human plasma. The goal of the method was to develop a microplate assay that measures FV activity during fibrin formation in human plasma. This novel microplate method outlines a simple, inexpensive, and rapid assay of FV activity in human plasma. The assay utilizes a kinetic microplate reader to monitor the absorbance change at 405nm during fibrin formation in human plasma (Figure 1) 13. The assay accurately measures the time, initial rate, and extent of fibrin clot formation. It requires only ?l quantities of plasma, is complete in 6 min, has high-throughput, is sensitive to 24-80pM FV, and measures the amount of unintentionally activated (1-stage activity) and thrombin-activated FV (2-stage activity) to obtain a complete assessment of its total functional activity (2-stage activity - 1-stage activity). Disseminated intravascular coagulation (DIC) is an acquired coagulopathy that most often develops from pre-existing infections 14. DIC is associated with a poor prognosis and increases mortality above the pre-existing pathology 15. The assay was used to show that in 9 patients with DIC, the FV 1-stage, 2-stage, and total activities were decreased, on average, by 54%, 44%, and 42%, respectively, compared with normal pooled human reference plasma (NHP). The FV microplate assay is easily adaptable to measure the activity of any coagulation factor. This assay will increase our understanding of FV biochemistry through a more accurate and complete measurement of its activity in research and clinical settings. This information will positively impact healthcare environments through earlier diagnosis and development of more effective treatments for coagulation disorders, such as DIC.

Tilley, Derek; Levit, Irina; Samis, John A.

2012-01-01

125

Comparison in the analytical performance between krypton and argon glow discharge plasmas as the excitation source for atomic emission spectrometry  

Microsoft Academic Search

The emission characteristics of ionic lines of nickel, cobalt, and vanadium were investigated when argon or krypton was employed\\u000a as the plasma gas in glow discharge optical emission spectrometry. A dc Grimm-style lamp was employed as the excitation source.\\u000a Detection limits of the ionic lines in each iron-matrix alloy sample were compared between the krypton and the argon plasmas.\\u000a Particular

Kazuaki Wagatsuma

2009-01-01

126

High-speed dispersed photographing of an open-air argon plasma plume by a grating-ICCD camera system  

Microsoft Academic Search

In this paper, an open-air argon plasma plume is generated at atmospheric pressure by a two-electrode jet device with sub-microsecond voltage pulses at a repetitive frequency of 1 kHz. Optical emission spectroscopy measurements showed that spectral irradiance from OH and N2 bands, and Ar lines, characterized the spectrum of the open-air argon plasma plume. The rotational temperature estimation of UV

Q. Xiong; A. Y. Nikiforov; X. P. Lu; C. Leys

2010-01-01

127

Plasma Chemistry of Octafluorocyclopentene/Argon/Oxygen Mixtures  

NASA Astrophysics Data System (ADS)

An octafluorocyclopentene (c-C5F8)/Ar/O2 plasma chemistry mechanism has been developed using a combination of quantum chemistry methods, a zero-dimensional plasma kinetics model, and results from quadrupole mass spectrometer (QMS) and actinometry experiments on a 200 mm capacitively coupled plasma source driven at 60 MHz. Quantum chemistry methods reveal that the degradation process of c-C5F8 under electron impact is sensitive to the characteristics of the isomeric structure of the products. We find that the primary loss process for c-C5F8 as a feed gas is electron impact dissociation into isomers of C5F7 via excitation to the triplet state of c-C5F8. Electron impact dissociation of C5F7 isomers leads finally to the production of C5F5 (an isomer with two conjugate ? bonds) and C5F6 (an isomer with two ? bonds and a folded ring structure). Through dissociative ionization and subsequent wall recombination C5F8 produces C4F6 less with less probability than the triplet state. C4F6 in turn produces C2F4, C2F2, and C4F4 (two double bonds) and is a gas phase pathway for the production of CF2. CF2 is also produced via electron impact dissociation of an isomer of C5F6. C5F5 is not readily dissociated by electron impact because of the existence of extra ? bonds that absorb electron energy in these species. The specific isomers encountered in c-C5F8 plasmas, C4F4, C5F5, and C5F6, have additional stability because of their structure. The etch precursor, atomic fluorine, is primarily produced from electron impact dissociation of the feed-gas and its degradation products. CF is produced from dissociation of CF2. CF3 is produced primarily from the walls. Because of their stability in the gas phase, C4F4, C5F6, and C5F5 are important polymer deposition species. The rate-limiting step for fluorine production is the electron impact dissociation of the triplet state of c-C5F8. Predicted etch rates are in good agreement with experimental data examining large substrate RF bias and low pressure.

Kang, Song-Yun; Sawada, Ikuo; Kondo, Yasuko; Ventzek, Peter L. G.

2008-08-01

128

[Spectroscopic investigation of the argon plasma discharge in quartz capillary at atmospheric pressure].  

PubMed

An arc plasma discharge with a long length of 20 cm was generated in a quartz capillary between two hollow needle electrodes in argon at atmospheric pressure with use of the sinusoidal power supply operating at 45 kHz, which was characterized by a very high electron density. The spectroscopic method of optical emission was employed to diagnose the characteristic parameters of the arc plasma discharge in the quartz capillary. The gas temperature was determined by simulating the OH A-X(0, 0) vibrational band around 300 nm and comparison with measured spectrum by means of optical emission spectroscopy. Furthermore, the electron density was measured by means of Stark broadening of the profile of Hbeta at 486.1 nm. The electron temperature was determined using a Boltzmann plot method. The experiment results show that in the argon arc plasma discharge generated in the quartz capillary at atmospheric pressure, the gas temperature of plasma is about (1 100 +/- 50)K, the electron density at the gas temperature of 1 100 K is approximately 10(14) cm(-3), and the corresponding electron temperature is (14 515 +/- 500)K. This work has accumulated some significant experimental parameters for the treatment of inner surface of large length-to-radius-ratio insulated dielectric tube using plasma, and the results are of great importance to the applications of this type of atmospheric-pressure plasma discharge. PMID:20672593

Huang, Wen-Tong; Li, Shou-Zhe; Guo, Qing-Chao; Zhang, Jia-Liang; Wang, De-Zhen; Ma, Teng-Cai

2010-05-01

129

Effects of magnetization on an expanding high-enthalpy plasma jet in argon  

NASA Astrophysics Data System (ADS)

The effects of magnetization on an expanding high-enthalpy plasma jet in argon are studied with a non-LTE model. The magnetic field is taken into account with a complete approach where the calculation of diffusion velocities, the electromagnetic field and the flow field are self-consistently coupled via the current density. Results of the simulations show that inside the plasma source there are no significant changes due to the magnetic field. However, in the expansion the magnetic field completely changes the appearance of the jet. Due to the magnetic field, shockwaves disappear and power dissipation not only takes place inside the source but also in the expansion region.

Peerenboom, K. S. C.; van Dijk, J.; Goedheer, W. J.; Kroesen, G. M. W.

2013-04-01

130

Atmospheric-pressure argon/oxygen plasma-discharge source with a stepped electrode  

SciTech Connect

The nonequilibrium glow discharge in argon mixed with oxygen at atmospheric pressure was generated in a parallel plate reactor with a stepped electrode powered by a 13.56 MHz radio-frequency power supplier. The stepped-electrode reactor consists of a narrow and wide gap structure. A strong electric field occurred at the narrow gap region preionizes Ar/O{sub 2} gas and assists to generate a large volumetric plasma in the wide gap region. Therefore, the stepped-electrode reactor makes it easy to operate Ar/O{sub 2} glow discharge, providing a stable, uniform, and broad plasma jet at atmospheric pressure.

Lim, Jin-Pyo; Uhm, Han S.; Li Shouzhe [Department of Molecular Science and Technology, Ajou University, San 5 Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of); State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams and Department of Physics, Dalian University of Technology, Dalian 116024 (China)

2007-01-29

131

Characteristics of argon plasma waveguide produced by alumina capillary discharge for short wavelength laser application  

SciTech Connect

We have reported the argon (Ar) plasma waveguide produced in an alumina (Al{sub 2}O{sub 3}) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 10{sup 16} W/cm{sup 2}. The electron density in the plasma waveguide was measured to be 1x10{sup 18} cm{sup -3}, in agreement with one-dimensional magnetrohydrodynamic (MHD) simulations. The MHD code was also used to evaluate the degree of ionization of argon (Ar) in the preformed plasma waveguide. The maximum ion charge state of Ar{sup 3+} in capillary discharge was measured and obtained in the MHD simulations. The spectrum of the propagated laser pulse in the Ar plasma waveguide was not modified and was well reproduced by a particle-in-cell simulations under initial ion charge state of Ar{sup 3+} in the preformed plasma waveguide. The optimum timing for the laser pulse injection was around 150 ns after initiation of a discharge with a peak current of 200 A.

Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Bobrova, Nadezhda; Sasorov, Pavel [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya Str. 25, 117218 Moscow (Russian Federation); Sakai, Shohei [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Sentoku, Yasuhiko [Department of Physics, University of Nevada, Mail Stop 220, Reno, Nevada 89506 (United States); Kodama, Ryosuke [Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2012-05-01

132

Electrical Aspects of Argon Micro-Cell Plasma with Applications in Bio-Medical Technology  

NASA Astrophysics Data System (ADS)

Argon micro-cell plasma (MCP) is believed to be a viable tool for performing micro-surgery. The non-thermal nature of the discharge allows an effective treatment of pathological tissue without causing thermal damage to its surroundings. This bio-medical application imposes a number of design challenges on the plasma configuration which we will address by computer-aided source design. In this contribution we present a numerical study with the Relaxation ConTinuum model (RCT) [1-2] of the characteristics of an atmospheric argon MCP which is maintained by an RF source. The focus will be on the influence of the geometry and the externally applied RF amplitude and frequency on the plasma properties. In particular, attention will be paid to the effect of pulsed-mode operation on the gas temperature. In addition, the influence of the frequency and the field in the wall sheath on the losses of the plasma species to the cell walls by drift-diffusion processes will be considered. [1] K. Okazaki, T. Makabe and Y. Yamaguchi, Appl. Phys. Lett. (54), 1742 (1989) [2] T. Makabe, "Advances in Low Temperature RF Plasmas" Elsevier, (2002)

Horiuchi, Yasuhiro; van Dijk, Jan; Makabe, Toshiaki

2003-10-01

133

Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics  

NASA Astrophysics Data System (ADS)

The afterglow of a dusty plasma of rf discharge in argon is simulated by the particle-in-cell-Monte Carlo collision (PIC-MCC) method. The experimental observation that heavy dust contamination of plasma leads to an anomalous increase in the electron density at the beginning of afterglow is explained by release of electrons from the dust surface. Under the assumption that the floating potential of particles is in equilibrium with plasma conditions, the fast cooling of electrons in afterglow plasma due to a rapid escape of hot electrons from the volume leads to a decrease in the magnitude of the floating potential and hence to a loss of charge by dust. The intensive desorption of electrons from nanoparticles is the origin of anomalous behavior of the electron density. At the next stage of afterglow, when the electrons become cool, the plasma decay is defined by ambipolar diffusion. The effect of metastable argon atoms is also considered. Additional ionization due to metastable atom collisions affects the electron temperature but does not change the behavior of the electron density qualitatively.

Alexandrov, A. L.; Schweigert, I. V.; Ariskin, D. A.

2013-04-01

134

Plasma vitronectin polymorphism in normal subjects and patients with disseminated intravascular coagulation.  

PubMed

Vitronectin, also known as serum-spreading factor or S-protein, mediates cell adhesion and inhibits formation of the membrane-lytic complex of complement and the rapid inactivation of thrombin by antithrombin III in the presence of heparin. Vitronectin is normally present in plasma at a concentration of approximately 300 micrograms/mL. The investigators quantified plasma vitronectin with an enzyme-linked immunosorbent assay and visualized reduced and nonreduced vitronectin by immunoblotting after separation of plasma or serum by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The concentration of plasma vitronectin was markedly reduced in some patients with disseminated intravascular coagulation, especially in those with liver failure; it was near normal in patients with metastatic cancer and acute leukemia. Patients with vitronectin levels less than 40% normal invariably had low fibrinogen and antithrombin III and a prolonged prothrombin time. In both normal and patient plasmas there was heterogeneity in the ratio of the 75,000- and 65,000-mol wt polypeptides of reduced vitronectin: 18% had mostly the 75,000-mol wt polypeptide, 59% had roughly equal amounts of the two polypeptides, and 22% had mostly the 65,000-mol wt polypeptide. This polymorphism is inherited and appears to be due to two alleles that are present with approximately equal frequency. The blotting patterns of vitronectin in reduced and nonreduced plasmas were largely unaltered in plasma of patients with defibrination syndrome, fibrinolysis, liver failure, sepsis, metastatic cancer, and acute leukemia. There was no evidence of fragmentation of vitronectin or formation of the disulfide-bonded complex of vitronectin and thrombin-antithrombin III that is found when blood is clotted. Thus these results corroborate in vitro observations that the liver is the major source of plasma vitronectin, suggest that vitronectin may become depleted during disseminated intravascular coagulation, and define a genetic polymorphism of vitronectin. PMID:2455567

Conlan, M G; Tomasini, B R; Schultz, R L; Mosher, D F

1988-07-01

135

Angular Distribution of Argon Ions and X-Ray Emissions in the Apf Plasma Focus Device  

NASA Astrophysics Data System (ADS)

Angular distribution of ion beam emission from an argon gas-filled plasma focus devices has been investigated using an array of five Faraday cups. The argon ion beam emission is found to be highly pressure-dependent and reaches its maximum at the pressure of 1 torr. The ions flux decreased as the working pressure increased; the maximum ion density at 1 torr was estimated to be around 9.24 × 1024 ions/steradian. Also, the study on the angular distribution of X-rays has been carried out using TLD-100 dosimeters. The intensity of ions reduced significantly at angles higher than ±11° but the X-ray distribution was bimodal, peaked approximately at ±15°.

Etaati, G. R.; Amrollahi, R.; Habibi, M.; Baghdadi, R.

2011-04-01

136

A method for evaluations on the radiation trapping in an inductively coupled plasma in argon  

NASA Astrophysics Data System (ADS)

One of the general challenges for the evaluation and interpretation of optical emission spectroscopy measurements is the occurrence of radiation trapping, which is also named self-absorption or opacity. A convenient technique to treat radiation trapping is the introduction of a parameter, which is called escape factor and gives a measure for the amount of radiation trapping. In this paper evaluations on the concept of escape factors are presented for an inductively coupled plasma in argon. Especially, the strong argon line at 811.53 nm, which arises from the transition of 2p9-1s5, is under consideration. To estimate escape factors for this line, a particular method is proposed and presented here. First experimental results are obtained under the restrictive assumptions that transitions into the resonant levels 1s2 and 1s4 are sufficiently optically thin and ratios of population densities are constant.

Scharwitz, Christian; Makabe, Toshiaki

2009-12-01

137

Fluid simulation for influence of metastable atoms on the characteristics of capacitively coupled argon plasmas  

SciTech Connect

One-dimensional self-consistent fluid model is used to simulate the capacitively coupled argon plasma, in which the metastable effect on the plasma parameters at different discharge conditions is investigated. The results show that due to the metastable atom existence, the bulk plasma density drops significantly, especially at high pressures, high voltages, and high frequencies, accompanied by the decrease in electron temperature in the bulk. When the pressure and voltage are high, the metastable atom density is characterized by a saddle distribution in the axis direction. However, with the decrease in voltage and pressure, the metastable atom density becomes a parabolic distribution. Besides, the curve of plasma density with frequency has a minimum, and so is the profile of metastable atom density.

Zhang Yuru; Xu Xiang; Wang Younian [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2010-03-15

138

Kinetic modelling for an atmospheric pressure argon plasma jet in humid air  

NASA Astrophysics Data System (ADS)

A zero-dimensional, semi-empirical model is used to describe the plasma chemistry in an argon plasma jet flowing into humid air, mimicking the experimental conditions of a setup from the Eindhoven University of Technology. The model provides species density profiles as a function of the position in the plasma jet device and effluent. A reaction chemistry set for an argon/humid air mixture is developed, which considers 84 different species and 1880 reactions. Additionally, we present a reduced chemistry set, useful for higher level computational models. Calculated species density profiles along the plasma jet are shown and the chemical pathways are explained in detail. It is demonstrated that chemically reactive H, N, O and OH radicals are formed in large quantities after the nozzle exit and H2, O2(1?g), O3, H2O2, NO2, N2O, HNO2 and HNO3 are predominantly formed as ‘long living’ species. The simulations show that water clustering of positive ions is very important under these conditions. The influence of vibrational excitation on the calculated electron temperature is studied. Finally, the effect of varying gas temperature, flow speed, power density and air humidity on the chemistry is investigated.

Van Gaens, W.; Bogaerts, A.

2013-07-01

139

Dysregulated coagulation associated with hypofibrinogenemia and plasma hypercoagulability: implications for identifying coagulopathic mechanisms in humans  

PubMed Central

SUMMARY Identifying coagulation abnormalities in patients with combined bleeding and thrombosis history is clinically challenging. Our goal was to probe the complexity of dysregulated coagulation in humans by characterizing pathophysiologic mechanisms in a patient with both bleeding and thrombosis. The patient is a 56-year old female with a history of hematomas, poor wound healing, and thrombosis (retinal artery occlusion and transient cerebral ischemia). She had a normal activated partial thromboplastin time, prolonged thrombin and reptilase times, and decreased functional and antigenic fibrinogen levels, and was initially diagnosed with hypodysfibrinogenemia. This diagnosis was supported by DNA analysis revealing a novel FGB mutation (c.656A>G) predicting a Q189R mutation in the mature B? chain that was present in the heterozygote state. However, turbidity analysis showed that purified fibrinogen polymerization and degradation were indistinguishable from normal, and B? chain subpopulations appeared normal by two-dimensional difference in-gel electrophoresis, indicating the mutated chain was not secreted. Interestingly, plasma thrombin generation testing revealed the patient’s thrombin generation was higher than normal and could be attributed to elevated levels of factor VIII (FVIII, 163-225%). Accordingly, in an arterial injury model, hypofibrinogenemic mice (Fgn+/?) infused with FVIII demonstrated significantly shorter vessel occlusion times than saline-infused Fgn+/? mice. Together, these data associate the complex bleeding and thrombotic presentation with combined hypofibrinogenemia plus plasma hypercoagulability. These findings suggest previous cases in which fibrinogen abnormalities have been associated with thrombosis may also be complicated by co-existing plasma hypercoagulability and illustrate the importance of “global” coagulation testing in patients with compound presentations.

Marchi, Rita; Walton, Bethany L.; McGary, Colleen S.; Lin, Feng-Chang; Ma, Alice D.; Pawlinski, Rafal; Mackman, Nigel; Campbell, Robert A.; Di Paola, Jorge; Wolberg, Alisa S.

2013-01-01

140

Thermophysical properties of carbon-argon and carbon-helium plasmas  

NASA Astrophysics Data System (ADS)

The calculated values of thermodynamic and transport properties of mixtures of carbon and argon, and carbon and helium, at high temperatures are presented in this paper. The thermodynamic properties are determined by the method of Gibbs free energy minimization, using standard thermodynamic tables. The transport properties including electron diffusion coefficients, viscosity, thermal conductivity and electrical conductivity are evaluated using the Chapman-Enskog method expanded up to the third-order approximation (second order for viscosity). Collision integrals are obtained using the most accurate cross-section data that could be located. The calculations, which assume local thermodynamic equilibrium, are performed for atmospheric pressure plasmas in the temperature range from 300 to 30 000 K for different pressures between 0.1 and 10 atm. The results are compared with those of previously published studies. Good agreement is found for pure argon and helium. Larger discrepancies occur for carbon and mixtures of carbon and argon, and carbon and helium; these are explained in terms of the different values of the collision integrals that were used. The results presented here are expected to be more accurate because of the improved collision integrals employed.

Wang, WeiZong; Rong, MingZhe; Murphy, Anthony B.; Wu, Yi; Spencer, Joseph W.; Yan, Joseph D.; Fang, Michael T. C.

2011-09-01

141

Argon ion implantation inducing modifications in the properties of benzene plasma polymers  

NASA Astrophysics Data System (ADS)

Benzene plasma polymer films were bombarded with Ar ions by plasma immersion ion implantation. The treatments were performed using argon pressure of 3 Pa and 70 W of applied power. The substrate holder was polarized with high voltage negative pulses (25 kV, 3 Hz). Exposure time to the immersion plasma, t, was varied from 0 to 9000 s. Optical gap and chemical composition of the samples were determined by ultraviolet-visible and Rutherford backscattering spectroscopies, respectively. Film wettability was investigated by the contact angle between a water drop and the film surface. Nanoindentation technique was employed in the hardness measurements. It was observed growth in carbon and oxygen concentrations while there was decrease in the concentration of H atoms with increasing t. Furthermore, film hardness and wettability increased and the optical gap decreased with t. Interpretation of these results is proposed in terms of the chain crosslinking and unsaturation.

Rangel, E. C.; Cruz, N. C.; Santos, D. C. R.; Algatti, M. A.; Mota, R. P.; Honda, R. Y.; Silva, P. A. F.; Costa, M. S.; Tabacniks, M. H.

2002-05-01

142

A nonequilibrium argon-oxygen planar plasma jet using a half-confined dielectric barrier duct in ambient air  

NASA Astrophysics Data System (ADS)

A nonequilibrium argon plasma jet with oxygen addition, generated in a planar dielectric duct and issuing into ambient air with one edge stuck on a dielectric plane, is reported for the first time. This argon-oxygen plasma jet can be operated at low applied voltage as a filamentary discharge at atmospheric pressure. The addition of a small amount of oxygen results in the increase of produced ozone concentration and continuous emissions of centering at about 185 nm, 205 nm, 230 nm, and 253 nm. The synergistic generation of short wavelength ultraviolet emissions and active species is significantly important for plasma applications.

Li, Qing; Takana, Hidemasa; Pu, Yi-Kang; Nishiyama, Hideya

2012-03-01

143

Particle-in-cell modeling of magnetized argon plasma flow through small mechanical apertures  

SciTech Connect

Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with millimeter wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length {approx}200{lambda}{sub D,e}-300{lambda}{sub D,e} forms at the location of the aperture and is found to be an electrostatic double layer, with axially separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength.

Sefkow, Adam B. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Cohen, Samuel A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

2009-05-15

144

TiN/TiCN multilayer films modified by argon plasma treatment  

NASA Astrophysics Data System (ADS)

TiN/TiCN multilayer films were deposited under direct current magnetron sputtering, and then were modified by application of an argon plasma process with an 1100 V substrate bias voltage. The combination of X-ray diffraction, field emission scanning electron microscopy and cross-sectional high resolution transmission electron microscopy was used to analyze the change of the film structure after Ar+ ion bombardment. It could be found that with the increase of the treatment time, the interface between the TiN layer and TiCN layer became more and more blurred and the film structure was also denser. Calculations on stress and hardness data had shown that argon plasma treatment considerably enhanced the mechanical properties of the film, which was mainly reflected in the hardness increasing from 21 GPa to 23.2 GPa, due to the creation of dense structure and fine grain. Comparison with original film, plasma-modified film exhibited substantially low friction behaviors and good wear resistance, especially the reduction of friction coefficient of TiN layer. There was a correlation between the excellent tribological properties of the film and the alteration of the film structure.

Zheng, Jianyun; Hao, Junying; Liu, Xiaoqiang; Gong, Qiuyu; Liu, Weimin

2013-09-01

145

Coherent anti-Stokes Raman spectroscopic measurement of air entrainment in argon plasma jets  

NASA Astrophysics Data System (ADS)

The concentration and temperature of air entrained into an argon plasma jet has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition to turbulence occurs, air is rapidly entrained into the jet core. The location of the transition region is thought to be driven by the rapid cooling of the jet and the resulting increase in Reynolds number.

Fincke, J. R.; Rodriquez, R.; Pentecost, C. G.

146

Spectroscopic study of a long high-electron-density argon plasma column generated at atmospheric pressure  

SciTech Connect

A stable plasma column is generated in a quartz tube using a pair of hollow electrodes driven by a sinusoidal power supply of 45 kHz at atmospheric pressure in argon. Two distinct operating modes (low-current and high-current modes) are identified through observing its discharge phenomena, measuring its electrical characteristics, and determining the gas temperatures by spectroscopic diagnosis of Q branch of UV OH spectrum. The electron density in the high-current mode is diagnosed by Stark broadening and is found to be two orders higher than that in low-current mode.

Li Shouzhe; Huang Wentong; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, and School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2010-02-15

147

Anion dynamics in the first 10 milliseconds of an argon-acetylene radio-frequency plasma  

NASA Astrophysics Data System (ADS)

The time evolution of the smallest anions (C2H- and H2CC-), just after plasma ignition, is studied by means of microwave cavity resonance spectroscopy (MCRS) in concert with laser-induced photodetachment under varying gas pressure and temperature in an argon-acetylene radio-frequency (13.56 MHz) plasma. These anions act as an initiator for spontaneous dust particle formation in these plasmas. With an intense 355 nm Nd?:?YAG laser pulse directed through the discharge, electrons are detached only from these anions present in the laser path. This results in a sudden increase in the electron density in the plasma, which can accurately and with sub-microsecond time resolution be measured with MCRS. By adjusting the time after plasma ignition at which the laser is fired through the discharge, the time evolution of the anion density can be studied. We have operated in the linear regime: the photodetachment signal is proportional to the laser intensity. This allowed us to study the trends of the photodetachment signal as a function of the operational parameters of the plasma. The density of the smallest anions steadily increases in the first few milliseconds after plasma ignition, after which it reaches a steady state. While keeping the gas density constant, increasing the gas temperature in the range 30-120 °C limits the number of smallest anions and saturates at a temperature of about 90 °C. A reaction pathway is proposed to explain the observed trends.

van de Wetering, F. M. J. H.; Beckers, J.; Kroesen, G. M. W.

2012-12-01

148

Theoretical investigation of thermophysical properties in two-temperature argon-helium thermal plasma  

SciTech Connect

The thermophysical properties of argon-helium thermal plasma have been studied in the temperature range from 5000 to 40 000 K at atmospheric pressure in local thermodynamic equilibrium and non-local thermodynamic equilibrium conditions. Two cases of thermal plasma considered are (i) ground state plasma in which all the atoms and ions are assumed to be in the ground state and (ii) excited state plasma in which atoms and ions are distributed over various possible excited states. The influence of electronic excitation and non-equilibrium parameter {theta} = T{sub e}/T{sub h} on thermodynamic properties (composition, degree of ionization, Debye length, enthalpy, and total specific heat) and transport properties (electrical conductivity, electron thermal conductivity, and thermal diffusion ratio) have been studied. Within the framework of Chapman-Enskog method, the higher-order contributions to transport coefficient and their convergence are studied. The influence of different molar compositions of argon-helium plasma mixture on convergence of higher-orders is investigated. Furthermore, the effect of different definitions of Debye length has also been examined for electrical conductivity and it is observed that electrical conductivity with the definition of Debye length (in which only electrons participate in screening) is less than that of the another definition (in which both the electrons and ions participate in screening) and this deviation increases with electron temperature. Finally, the effect of lowering of ionization energy is examined on electron number density, Debye length, and higher-order contribution to electrical conductivity. It is observed that the lowering of the ionization energy affects the electron transport-properties and consequently their higher-order contributions depending upon the value of the non-equilibrium parameter {theta}.

Sharma, Rohit; Singh, Kuldip [Department of Physics, Guru Nanak Dev University, Amritsar (India); Singh, Gurpreet [Department of Physics, DAV College, Bathinda (India)

2011-08-15

149

Contributions of Contact Activation Pathways of Coagulation Factor XII in Plasma  

PubMed Central

Activation of human blood plasma coagulation by contact with hydrophilic or hydrophobic surfaces (procoagulants) is dominated by kallikrein (Kal)-mediated activation of the blood zymogen FXII (Hageman Factor). Mathematical modeling of prekallikrein (PK)-deficient platelet-poor plasma (dPKPPP) and PK-reconstituted dPKPPP (RdPKPPP) coagulation shows that autoactivation of FXII ( FXII?surfaceFXIIa) produces no more than about 25% of the total FXIIa produced by the intrinsic pathway. Autoactivation and reciprocal-activation increase in the same proportion with procoagulant surface energy (water-wettability), while total amount of FXIIa produced per-unit-area procoagulant remains roughly constant for any particular procoagulant. These results suggest that procoagulant surfaces initiate the intrinsic cascade by producing a bolus of FXIIa in proportion to surface energy or surface area but play no additional role in subsequent molecular events in the cascade. Results further suggest that reciprocal-activation occurs in proportion to the amount of FXIIa produced by the initiating autoactivation step.

Chatterjee, Kaushik; Guo, Zhe; Vogler, Erwin A.; Siedlecki, Christopher A.

2010-01-01

150

Atomic data generation and collisional radiative modeling of argon II, argon III, and neon I for laboratory and astrophysical plasmas  

NASA Astrophysics Data System (ADS)

Accurate knowledge of atomic processes plays a key role in modeling the emission in laboratory as well as in astrophysical plasmas. These processes are included in a collisional-radiative model and the results are compared with experimental measurements for Ar and Ne ions from the ASTRAL (Auburn Steady sTate Research fAciLity) experiment. The accuracy of our model depends upon the quality of the atomic data we use. Atomic data for near neutral systems present a challenge due to the low accuracy of perturbative methods for these systems. In order to improve our model we rely on non-perturbative methods such as R - Matrix and RMPS ( R -Matrix with Pseudo-States) to include correlation in the collision cross-sections. In the case of Ar + we compared R -Matrix electron-impact excitation data against the results from a new RMPS calculation. The aim was to assess the effects of continuum-coupling effects on the atomic data and the resulting spectrum. We do our spectral modeling using the ADAS suite of codes. Our collisional-radiative formalism assumes that the excited levels are in quasi- static equilibrium with the ground and metastable populations. In our model we allow for N e and T e variation along the line of sight by fitting our densities and temperature profiles with those measured within the experiment. The best results so far have been obtained by the fitting of the experimental temperature and density profiles with Gaussian and polynomial distribution functions. The line of sight effects were found to have a significant effect on the emission modeling. The relative emission rates were measured in the ASTRAL helicon plasma source. A spectrometer which features a 0.33 m Criss-Cross Scanning monochromator and a CCD camera is used for this study. ASTRAL produces bright intense Ar and Ne plasmas with n e = 10 11 to 10 13 cm -3 and T e = 2 to 10 eV. A series of 7 large coils produce an axial magnetic field up to 1.3 kGauss. A fractional helix antenna is used to introduce RF power up to 2 kWatt. Two RF compensated Langmuir probes are used to measure T e and N e . In a series of experiment Ar II, Ar III, and Ne transitions are monitored as a function of T e , while Ne is kept nearly constant. Observations revealed that T e is by far the most significant parameter affecting the emission rate coefficients, thus confirming our predictions. The spectroscopy measurements are compared with those from our spectral modeling which in turn help us to compare the effectiveness of the new atomic data calculations with those from other calculations. We performed a new R -Matrix calculation for Ar 2+ . Emission from Ar 2+ is seen in planetary nebulae, in H II regions, and from laboratory plasmas. Our calculation improved upon existing electron-impact excitation data for the 3p 4 configuration of Ar 2+ and calculated new data for the excited levels. Electron-impact excitation collision strengths were calculated using the R - Matrix intermediate-coupling (IC) frame-transformation method and the R -Matrix Breit-Pauli method. Excitation cross-sections are calculated between all levels of the configurations 3s 2 3p 4 , 3s 3p 5 , 3p 6 , 3p 5 3d, and 3s 2 3p 3 nl (3d <= nl <= 5s). Maxwellian effective collision strengths are generated from the collision strength data. Good agreement is found in the collision strengths calculated using the two R -Matrix methods. The effects of the new data on line ratio diagnostics were studied. The collision strengths are compared with literature values for transitions within the 3s 2 3p 4 configuration. The new data has a small effect on T e values obtained from the I (l7135Å + l7751Å)/ I (l5192Å) line ratio, and a larger effect on the N e values obtained from the I (l7135Å)/ I (l9m m ) line ratio. The final effective collision strength data is archived online. Neon as well as Argon is a species of current interest in fusion TOKAMAK studies. It is used for radiative cooling of the divertor region and for disruption mitigation. It could also be useful as a spectral diagnostic if better atomic data w

Munoz Burgos, Jorge Manuel

151

Stark broadening measurement of the electron density in an atmospheric pressure argon plasma jet with double-power electrodes  

SciTech Connect

Characteristics of a double-power electrode dielectric barrier discharge of an argon plasma jet generated at the atmospheric pressure are investigated in this paper. Time-averaged optical emission spectroscopy is used to measure the plasma parameters, of which the excitation electron temperature is determined by the Boltzmann's plot method whereas the gas temperature is estimated using a fiber thermometer. Furthermore, the Stark broadening of the hydrogen Balmer H{sub {beta}} line is applied to measure the electron density, and the simultaneous presence of comparable Doppler, van der Waals, and instrumental broadenings is discussed. Besides, properties of the jet discharge are also studied by electrical diagnosis. It has been found that the electron densities in this argon plasma jet are on the order of 10{sup 14} cm{sup -3}, and the excitation temperature, gas temperature, and electron density increase with the applied voltage. On the other hand, these parameters are inversely proportional to the argon gas flow rate.

Qian Muyang; Ren Chunsheng; Wang Dezhen; Zhang Jialiang; Wei Guodong [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2010-03-15

152

Radiative Divertor Plasma Behavior in L- and H-Mode Discharges with Argon Injection in EAST  

NASA Astrophysics Data System (ADS)

Introducing strong radiative impurities into divertor plasmas has been considered as an important way to mitigate the peak heat load at the divertor target plate for ITER, and will be employed in EAST for high power long pulse operations. To this end, radiative divertor experiments were explored under both low (L) and high (H) - mode confinement regimes, for the first time in EAST, with the injection of argon and its mixture (25% Ar in D2). The Ar injection greatly reduced particle and heat fluxes to the divertor in L-mode discharges, achieving nearly complete detached divertor plasma regimes for both single null (SN) and double null (DN) configurations, without increasing the core impurity content. In particular, the peak heat flux was reduced by a factor of ~6, significantly reducing the intrinsic in-out divertor asymmetry for DN, as seen by both the new infra-red camera and the Langmuir probes at the divertor target. Promising results have also been obtained in the H-modes with argon seeding, demonstrating a significant increase in the frequency and decrease in the amplitude of the edge localized modes (ELMs), thus reducing both particle and heat loads caused by the ELMs. This will be further explored in the next experimental campaign with increasing heating power for long pulse operations.

Wang, Dongsheng; Guo, Houyang; Shang, Yizi; Gan, Kaifu; Wang, Huiqian; Chen, Yingjie; Liu, Shaocheng; Wang, Liang; Gao, Wei; Xiang, Lingyan; Wu, Zhenwei; Luo, Guangnan; The EAST Team

2013-07-01

153

Energy loss of argon in a laser-generated carbon plasma  

SciTech Connect

The experimental data presented in this paper address the energy loss determination for argon at 4 MeV/u projectile energy in laser-generated carbon plasma covering a huge parameter range in density and temperature. Furthermore, a consistent theoretical description of the projectile charge state evolution via a Monte Carlo code is combined with an improved version of the CasP code that allows us to calculate the contributions to the stopping power of bound and free electrons for each projectile charge state. This approach gets rid of any effective charge description of the stopping power. Comparison of experimental data and theoretical results allows us to judge the influence of different plasma parameters.

Frank, A.; Harres, K.; Hoffmann, D. H. H.; Knobloch-Maas, R.; Nuernberg, F.; Pelka, A.; Schaumann, G.; Schoekel, A.; Schollmeier, M.; Schumacher, D.; Schuetrumpf, J.; Roth, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany); Blazevic, A.; Hessling, T. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany); Grande, P. L. [Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, Porto Alegre 91501-970, RS (Brazil); Kuznetsov, P. G.; Vatulin, V. V.; Vinokurov, O. A. [RFNC-VNIIEF, Sarov, Nizhny Novgorod Region 607190 (Russian Federation); Schiwietz, G. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Glienicker Strasse 100, D-14109 Berlin (Germany)

2010-02-15

154

Comparative analysis of polychlorinated biphenyl decomposition processes in air or argon (+oxygen) thermal plasma.  

PubMed

Thermal plasmas may solve one of the biggest toxic waste disposal problems. The disposal of polychlorinated biphenyls (PCBs) is a long standing problem which will get worse in the coming years, when 180000 tons of PCB-containing wastes are expected to accumulate in Europe (Hot ions break down toxic chemicals, New Scientist, 16 April 1987, p. 24.). The combustion of PCBs in ordinary incinerators (at temperature T approximately 1100 K, as measured near the inner wall of the combustion chamber (European Parliament and Council Directive on Incineration of Waste (COM/99/330), Europe energy, 543, Sept. 17, 1999, 1-23.)) can cause more problems than it solves, because highly toxic dioxins and dibenzofurans are formed if the combustion temperature is too low (T<1400 K). The paper presents a thermodynamic consideration and comparative analysis of PCB decomposition processes in air or argon (+oxygen) thermal plasmas. PMID:10828388

Kostic, Z G; Stefanovic, P L; Pavlovi?, P B

2000-07-10

155

Two-temperature thermodynamic and transport properties of argon-hydrogen and nitrogen-hydrogen plasmas  

NASA Astrophysics Data System (ADS)

Two-temperature thermodynamic and transport properties of argon-hydrogen and nitrogen-hydrogen plasma mixtures are presented, chemical equilibrium being achieved. The calculations of transport properties are carried out using the Chapman-Enskog method up to the third order; when electron temperature differs from that of heavy particles, calculations are performed following both a recent two-temperature theory by Rat et al that retains the coupling between electrons and heavy particles and a simplified decoupling theory proposed by Devoto. No relevant discrepancies between results obtained using these two approaches have been found, allowing the simplified method of Devoto to be still used in the computation of non-equilibrium transport properties like thermal conductivity, electrical conductivity and viscosity, with the exception of some diffusion coefficients. Results for composition, mass density, specific heat, thermal conductivity, electrical conductivity and viscosity of atmospheric pressure plasmas in the electron temperature range 300-40 000 K are reported.

Colombo, V; Ghedini, E; Sanibondi, P

2009-03-01

156

Deposition of a-SiC:H using organosilanes in an argon/hydrogen plasma  

SciTech Connect

Selected organosilanes were examined as precursors for the deposition of amorphous hydrogenated silicon carbide in an argon/hydrogen plasma. Effect of process variables on the quality of the films was established by means of FTIR, Auger spectroscopy, XPS, XRD, chemical analysis, and weight losses upon pyrolysis. For a given power level there is a limiting feeding rate of the precursor under which operation of the system is dominated by thermodynamics and leads to high quality silicon carbide films that are nearly stoichiometric and low in hydrogen. Beyond that limit, carbosilane polymer formation and excessive hydrogen incorporation takes place. The hydrogen content of the plasma affects the deposition rate and the hydrogen content of the film. In the thermodynamically dominated regime the nature of the precursor has no effect on the quality of the film, it affects only the relative utilization efficiency.

Maya, L.

1993-12-01

157

Diagnostics of the influence of levitating microparticles on the radiofrequency argon plasma  

NASA Astrophysics Data System (ADS)

The effect of a levitating cloud of microparticles on the parameters of a radiofrequency (RF) plasma has been studied by means of two experimental techniques. Axial distributions of 1 s excited states of argon were measured by a self-absorption method. A correction of a standard self-absorption method for the extinction of the light by the levitating microparticles is proposed. In addition the electron temperature was estimated using the optical emission spectroscopy. Measurements at the same discharge conditions in a microparticle-free discharge and discharge, containing a cloud of levitating microparticles, revealed the non-local influence of the microparticle cloud on the discharge plasma. The most probable cause of this influence is the disturbance of the ionization balance by the levitating microparticles.

Pustylnik, Mikhail Y.; Mitic, Slobodan; Klumov, Boris A.; Morfill, Gregor E.

2010-11-01

158

Atomic emission spectroscopic characteristics of argon plasma in a pulsed discharge nozzle ion source  

NASA Astrophysics Data System (ADS)

A specially designed pulsed discharge nozzle (PDN) ion source, a glow discharge pulsed supersonic jet, was constructed. The optical emission spectra of argon I and II in the region of 300-800 nm were observed and analyzed. The gas temperature of 3500 K and the ion one of 11?100 K were simulated by the Boltzmann plot method, and the electron density was simulated by Stark broadening of the H? line. Owing to the big difference between the temperatures of Ar I and II, the plasma in the PDN is concluded to be in non-local thermodynamic equilibrium. The evolution of plasma parameters in the PDN was investigated also by using time-dependent emission spectra.

Yang, J.; Zhao, D.-M.; Ma, X.

2013-09-01

159

Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications  

SciTech Connect

The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated. 10 references.

Barbi, E.; Mahan, J.R.; O'brien, W.F.; Wagner, T.C.

1989-04-01

160

Energy loss of argon in a laser-generated carbon plasma.  

PubMed

The experimental data presented in this paper address the energy loss determination for argon at 4 MeV/u projectile energy in laser-generated carbon plasma covering a huge parameter range in density and temperature. Furthermore, a consistent theoretical description of the projectile charge state evolution via a Monte Carlo code is combined with an improved version of the CasP code that allows us to calculate the contributions to the stopping power of bound and free electrons for each projectile charge state. This approach gets rid of any effective charge description of the stopping power. Comparison of experimental data and theoretical results allows us to judge the influence of different plasma parameters. PMID:20365659

Frank, A; Blazevi?, A; Grande, P L; Harres, K; Hessling, T; Hoffmann, D H H; Knobloch-Maas, R; Kuznetsov, P G; Nürnberg, F; Pelka, A; Schaumann, G; Schiwietz, G; Schökel, A; Schollmeier, M; Schumacher, D; Schütrumpf, J; Vatulin, V V; Vinokurov, O A; Roth, M

2010-02-04

161

Cavity ringdown measurements of OH radicals in microwave induced argon plasma assisted combustion of methane/air mixtures  

NASA Astrophysics Data System (ADS)

In order to study the mechanism of plasma assisted combustion, we have developed a system that injects a nonthermal low temperature atmospheric argon plasma into the burning flame of lean methane/air mixtures. The experimental results demonstrated the flammability enhancement of plasma assisted combustion in the lean flame of a fuel equivalence ratio as low as 0.2. In the argon plasma assisted combustion flame, we observed three different zones which were pure argon plasma zone, plasma-flame interacting zone, and pure flame zone. Optical emission studies showed distinct spectroscopic fingerprints of each zone. The emission intensities of OH radicals increased dramatically moving from pure plasma zone to plasma-flame interacting zone, and dropped severely from plasma-flame interacting zone to pure flame zone. In addition to the optical emission spectroscopy study, cavity ringdown spectroscopy (CRDS) was also applied in the measurements of absolute ground state OH radical number densities in the plasma assisted combustion flame. Results showed that the ground state OH radical number densities in the pure flame zone are on the order of 10^15 molecule/cm^3, and increasing within the range of first few millimeters from the combustor nozzle.

Wu, Wei; Wang, Chuji

2012-10-01

162

Water-repellent improvement of polyester fiber via radio frequency plasma treatment with argon\\/hexamethyldisiloxane (HMDSO) at atmospheric pressure  

Microsoft Academic Search

This work reports the formation of water-repellent surface on polyethyleneterephthalate (PET) fiber via plasma polymerization at atmospheric pressure. PET fiber was treated by employing a radio frequency (RF) plasma in a mixture of argon gas and gas-phase hexamethyldisiloxane (HMDSO). The surface morphologies and the chemical functional groups of plasma-treated fibers were characterized by a scanning electron microscopy, a Fourier transform

Young Yeon Ji; Hong Ki Chang; Yong Cheol Hong; Suck Hyun Lee

2009-01-01

163

Spectroscopic characterization of atmospheric pressure argon plasmas sustained with the Torche à Injection Axiale sur Guide d'Ondes  

NASA Astrophysics Data System (ADS)

An argon microwave (2.45 GHz) plasma produced by a microwave plasma torch known as "Torche à Injection Axiale sur Guide d'Ondes" (TIAGO) in air ambience at atmospheric pressure was experimentally characterized. The conditions for appropriate TIAGO torch operation in argon and flame morphology were researched under several experimental conditions of gas flow (0.15-5.00 L · min-1) rates and microwave input powers (100-1000 W). Gas temperature and electron density values were studied by means of optical emission spectroscopy. Besides, the processes inside the discharge and their interaction with the surrounding atmosphere were described according to the recorded spectra.

Rincón, R.; Muñoz, J.; Sáez, M.; Calzada, M. D.

2013-03-01

164

ULTRAVIOLET INDUCED MOTION OF A FLUORESCENT DUST CLOUD IN AN ARGON DIRECT CURRENT GLOW DISCHARGE PLASMA  

SciTech Connect

Dusty plasmas consist of electrons, ions, neutrals and nm-?m sized particles commonly referred to as dust. In man-made plasmas this dust may represent impurities in a tokamak or plasma etching processing. In astrophysical plasmas this dust forms structures such as planetary rings and comet tails. To study dusty plasma dynamics an experiment was designed in which a 3:1 silica (<5 ?m diameter) and fl uorescent dust mixture was added to an argon DC glow discharge plasma and exposed to UV radiation. This fl uorescent lighting technique offers an advantage over laser scattering (which only allows two-dimensional slices of the cloud to be observed) and is simpler than scanning mirror techniques or particle image velocimetry. Under typical parameters (P=150 mTorr, V anode= 100 V, Vcathode= -400 V, Itotal < 2mA) when the cloud is exposed to the UV light (100W, ? = 365 nm) the mixture fl uoresces, moves ~2mm towards the light source and begins rotating in a clockwise manner (as seen from the cathode). By calibrating a UV lamp and adjusting the relative intensity of the UV with a variable transformer it was found that both translational and rotational velocities are a function of UV intensity. Additionally, it was determined that bulk cloud rotation is not seen when the dust tray is not grounded while bulk translation is. This ongoing experiment represents a novel way to control contamination in man-made plasmas and a path to a better understanding of UV-bathed plasma systems in space..

Hvasta, M.G.; and Zwicker, A.

2008-01-01

165

a Surface Wave Sustained Plasma Source of Supersonic Nozzle Beams of Metastable Argon Atoms  

NASA Astrophysics Data System (ADS)

The characterization of a new beam source of metastable argon atoms is reported in this dissertation. The source, the surfajet, is based on expanding a plasma sustained by electromagnetic surface waves in a quartz tube through a simple converging nozzle and extracting a beam from the supersonic free-expansion jet. The 2.45 GHz surface waves are produced by a surfatron wave launcher designed to launch the fundamental transverse magnetic (TM) cylindrical mode in the plasma-dielectric waveguide. The waves travel along the interface between the plasma and the discharge tube (4 mm i.d., 6 mm o.d.) to a cooled supersonic nozzle located 10.5 cm from the launcher. The wave fields sustain the argon plasma column, whose length depends on the microwave power absorbed in the plasma up to a threshold value of power corresponding to the plasma extending to the nozzle exit. An increase of absorbed power beyond this threshold produces a linear rise in the gas temperature at the nozzle and excitation in the expansion jet. Vacuum ultraviolet spectroscopy of the jet indicates lack of significant Ar_2 ^{*} excimer formation. An antenna is used to measure axial profiles of the radial electric field intensity of the surface wave. The profiles indicate the presence of a reflected wave for powers exceeding the threshold. Axial profiles of the surface wave phase are also measured, from which electron density profiles are determined. For powers exceeding the threshold, a peak occurs in the electron density profile corresponding to the reflected wave. The intensity and velocity distribution of metastables in the beam are determined for 190 mu and 350 mu diameter nozzles from time-of-flight measurements fitted to a model distribution. The beam velocity is found to be proportional to the square root of the source temperature, as predicted by the continuum treatment of the expansion. The beam thermal velocity decreases with the product of the source pressure and the nozzle diameter, with the lowest achieved parallel beam temperature being 23 K. The terminal parallel speed ratio increases with the pressure-diameter product and reaches a maximum of 8.5. The absolute intensity of metastables in the beam is determined through the calibration of the channeltron multiplier that serves as the particle detector. The maximum intensity of 6.2 times 10 ^{14} s^ {-1} sr^{-1} with a speed ratio of 4.1 is achieved for a discharge with a 13.9 sccm mass flow through a 350 mu diameter nozzle. The metastable intensity can be correlated to the absorbed power per unit mass flow; this is explained by a simple model of a recombining plasma in the expansion jet.

Bannister, Mark Erskine

1992-01-01

166

Effects of natural convection on the characteristics of long laminar argon plasma jets issuing upwards or downwards into ambient air---a numerical study  

Microsoft Academic Search

A modelling study has been performed on the effect of natural convection on the characteristics of a long laminar argon plasma jet issuing into ambient air. In this study the plasma jet is taken to be flowing vertically upwards or downwards, and the combined diffusion coefficient method has been used to treat the diffusion of ambient air into the argon

Kai Cheng; Xi Chen

2004-01-01

167

Anode attachment of torch plasma arc with high-speed lateral gas air and axial plasma gas argon  

NASA Astrophysics Data System (ADS)

Torch plasma arcs have useful high-energy and high-current characteristics. Torch plasma arcs can be flexible even if exposed to high-speed laterally flowing gases. This study measured the length, voltage, input power, heat power and heat efficiency of a torch plasma arc to the anode to elucidate their influence upon the plasma torch arc anode attachment with a high-velocity laterally flowing gas. That velocity was varied from 0 to 60 m s-1. The axial plasma gas argon flow rates used were 4, 8 and 12 slpm. Consequently, the input power increased about 8000-16 000 W with these lateral gas air velocities. The heat efficiency decreased with lateral gas air velocity from about 50% to 25% at a current of I = 150 A. The torch plasma arc length, La, was ca 1 cm. The results of this study are applicable for providing electrical power from the ground to high-speed vehicles or vice versa and for reducing anode erosion by anode spot movement.

Iwao, Toru; Beppu, Takuya; Ishikawa, Shuhei; Inaba, Tsuginori

2004-04-01

168

Correlations Between Plasma Variables and the Deposition Process of Si Films from Chlorosilanes in Low Pressure RF Plasma of Argon and Hydrogen.  

National Technical Information Service (NTIS)

The dissociation of chlorosilanes to silicon and its deposition on a solid substrate in a RF plasma of mixtures of argon and hydrogen were investigated as a function of the macrovariables of the plasma. The dissociation mechanism of chlorosilanes and HCl ...

R. Avni U. Carmi A. Grill R. Manory E. Grossman

1984-01-01

169

Large Amplitude Shear Alfvén Waves and a Local Density Perturbation in an Argon Plasma  

NASA Astrophysics Data System (ADS)

Large amplitude shear Alfvén waves (B_wave/B0 ~ 10-3) and the propagation of a local density perturbation have been studied using a diverse combination of diagnostics in the Large Plasma Device at UCLA. The waves are launched from an inductive antenna that drives current along the the background magnetic field (B_0), and they propagate along the axis of a 9m long, 0.5m diameter cylindrical argon plasma. Typical plasma parameters are n_e=1.4×10^12 cm-3, T_e=4 eV, T_i=1 eV, and B_0=1500 G. Laser-induced fluorescence (LIF) measurements at many spatial locations give a detailed description of the ion motion---i.e., the time-resolved 2D ion velocity distributions in several planes perpendicular to B_0. These are combined with extensive probe measurements of B_wave to compute E_wave, which includes a B-field-aligned component. The velocity distributions and wave field measurements are further correlated with probe measurements of n_e, T_e, and ion saturation current to track the density perturbation near the center of the wave pattern and yield a detailed picture of the wave-particle interaction as well as the overall evolution of the plasma.

Palmer, Nathan E.; Gekelman, Walter

2000-10-01

170

Study of emission of a volume nanosecond discharge plasma in xenon, krypton and argon at high pressures  

Microsoft Academic Search

The emission properties of a volume nanosecond discharge plasma produced in xenon, krypton and argon at high pressures in a discharge gap with a cathode having a small radius of curvature are studied. Spectra in the range 120–850 nm and amplitude—time characteristics of xenon emission at different regimes and excitation techniques are recorded and analysed. It is shown that upon

E Kh Baksht; Mikhail I Lomaev; D V Rybka; Viktor F Tarasenko

2006-01-01

171

Scanning-electron-microscopy study of argon-plasma-treated and untreated peel-test Kevlar 49/epoxy laminates  

SciTech Connect

It is concluded that a 200-watt RF argon plasma treatment of Kevlar fibers for four minutes increases the fiber/epoxy interfacial bonding. However, as a consequence of this increase in fiber-matrix bonding, the fiber is readily fibrillated during laminate deformation and failure.

Ingraham, J.A.; Walton, J.; Pruneda, C.O.; Morgan, R.J.

1982-10-01

172

Energy spectrum of argon ions emitted from Filippov type Sahand plasma focus.  

PubMed

The energy and flux of the argon ions produced in Sahand plasma focus have been measured by employing a well-designed Faraday cup. The secondary electron emission effects on the ion signals are simulated and the dimensions of Faraday cup are optimized to minimize these effects. The measured ion energy spectrum is corrected for the ion energy loss and charge exchange in the background gas. The effects of the capacitor bank voltage and working gas pressure on the ion energy spectrum are also investigated. It has been shown that the emitted ion number per energy increases as the capacitor bank voltage increases. Decreasing the working gas pressure leads to the increase in the number of emitted ion per energy. PMID:23902061

Mohammadnejad, M; Pestehe, S J; Mohammadi, M A

2013-07-01

173

Comparison of various NLTE codes in computing the charge-state populations of an argon plasma  

SciTech Connect

A comparison among nine computer codes shows surprisingly large differences where it had been believed that the theroy was well understood. Each code treats an argon plasma, optically thin and with no external photon flux; temperatures vary around 1 keV and ion densities vary from 6 x 10/sup 17/ cm/sup -3/ to 6 x 10/sup 21/ cm/sup -3/. At these conditions most ions have three or fewer bound electrons. The calculated populations of 0-, 1-, 2-, and 3-electron ions differ from code to code by typical factors of 2, in some cases by factors greater than 300. These differences depend as sensitively on how may Rydberg states a code allows as they do on variations among computed collision rates. 29 refs., 23 figs.

Stone, S.R.; Weisheit, J.C.

1984-11-01

174

Argon Plasma-Induced Graft Polymerization of PEGMA on Chitosan Membrane Surface for Cell Adhesion Improvement  

NASA Astrophysics Data System (ADS)

For its biocompatibility and biodegradability, chitosan has had considerable attention for biomedical applications in recent years. In this paper, polymerization of poly (ethylene glycol) methyl ether methacrylate (PEGMA) was grafted onto chitosan membrane surface through argon plasma-induced graft polymerization. The surface properties after modification were characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The results indicated that PEGMA can be grafted successfully onto chitosan membrane surface. The surface hydrophilicity and free energy were improved and the surface roughness increased after modification. The adhesion of a human corneal epithelial cell (HCEC) on chitosan membrane surface was enhanced due to improvement of surface free energy and roughness.

Yin, Shiheng; Ren, Li; Wang, Yingjun

2013-10-01

175

Time- and space-resolved spectroscopic characterization of a laser carbon plasma plume in an argon background  

NASA Astrophysics Data System (ADS)

We present time- and space-resolved spectroscopic observations of a laser-produced carbon plasma, in an argon background. An Nd?:?YAG laser pulse, 370 mJ, 3.5 ns, at 1.06 µm, with a fluence of 6.9 J cm-2, is used to produce a plasma from a solid graphite target in a 0.5 to 415 mTorr argon background. The spectral emission in the visible is recorded with 15 ns time resolution. We use 20 ns time resolution plasma imaging, filtered at characteristic carbon species emission wavelengths, to study the dynamics of the expanding plasma. The carbon plasma emission is found to evolve from the characteristic of single ionized carbon, to a more complex one, where C2 and C3 molecular bands dominate. Several plasma fronts, with either ionic or molecular composition, are seen to detach from the laser target plasma. The temporal and spatial features of the molecular carbon species evolution are found to be dependent on the actual argon background pressure.

Ruiz, H. M.; Guzmán, F.; Favre, M.; Bhuyan, H.; Chuaqui, H.; Wyndham, E. S.

2012-06-01

176

Investigation of magnetic-pole-enhanced inductively coupled nitrogen-argon plasmas  

SciTech Connect

This article presented the features of the mixed mode and H mode in magnetic pole enhanced, inductively coupled Ar-N{sub 2} plasmas using RF-compensated Langmuir probe measurements. To fully characterize plasma parameters and electron energy probability functions (EEPFs), the gas pressure and argon content were varied. It was observed that with increasing the nitrogen content and gas pressure, the critical RF power to sustain H mode increases; this increase was more prominent for pure nitrogen discharge at higher pressure. The electron number density (n{sub e}) shows increasing trend with increasing RF power, while at higher gas pressures, the electron number density decreases at fixed RF power. Mostly, the EEPFs show a Maxwellian distribution even at low RF power (for higher argon content in the discharge) and at moderate RF power (for higher or pure nitrogen content in the discharge) for pressures of 15-60 mTorr. With increasing the nitrogen content in the mixture, the low energy part of the EEPF is more Druyvesteyn with a distorted high energy tail at low RF power. At fixed RF power, the slope of EEPF changes sharply with increasing pressure. It was observed that in hybrid mode, the EEPF at higher gas pressure (75 mTorr) in a pure nitrogen discharge shows a flat hole near the average electron energy of 3 eV and changes to Maxwellian distribution in H mode. The skin depth versus RF power shows that the skin depth is smaller than the critical dimension of the chamber, regardless of the gas type and the gas pressure.

Jan, F.; Zakaullah, M. [Department of Physics, Quaid-i-Azam University Islamabad, Islamabad 45320 (Pakistan); Khan, A. W.; Saeed, A. [National Centre for Physics, Quaid-i-Azam University Campus Islamabad, Islamabad 45320 (Pakistan)

2012-09-15

177

High-speed dispersed photographing of an open-air argon plasma plume by a grating-ICCD camera system  

NASA Astrophysics Data System (ADS)

In this paper, an open-air argon plasma plume is generated at atmospheric pressure by a two-electrode jet device with sub-microsecond voltage pulses at a repetitive frequency of 1 kHz. Optical emission spectroscopy measurements showed that spectral irradiance from OH and N2 bands, and Ar lines, characterized the spectrum of the open-air argon plasma plume. The rotational temperature estimation of UV OH band spectra indicated the gas temperature of the plasma plume to be as low as room temperature. A novel diagnostic method, based on two dispersion gratings and an ICCD camera, was designed for investigating the time- and space-resolved propagation behaviour of the excited radicals in the plasma plume. Based on the dispersion feature of gratings, a series of dispersed plasma optical emission volumes, which were formed by irradiance from different excited radiation emitters (excited species) in the plasma plume, were captured in the form of high-speed images by the ICCD camera. From the sequence of dispersed emission images, it is possible to observe the time- and space-resolved behaviour of different excited species in the plasma, and meanwhile, to understand the propagation dynamics of the open-air argon plasma plume. It is found that the OH bands' emission volume exhibited a propagation behaviour distinct from that of N2 and Ar emission volumes. The OH emissions decayed immediately as soon as the plasma travelled out from the nozzle, but were able to last for a longer duration time inside the nozzle than both N2 and Ar emissions. The N2 bands' emission volumes propagated to a far distance and formed the whole length of the argon plasma plume in the surrounding air. The Ar emissions decayed rapidly for the plasma inside and outside the nozzle due to the adverse effect of impurities, in particular the large concentration of diffused air in the open space. These distinct types of dynamic behaviour of the dispersed plasma emission volumes are attributed to the different generation and quenching mechanisms of their corresponding excited species and they shed light on the clear propagation dynamics of the argon plasma plume in open air.

Xiong, Q.; Nikiforov, A. Y.; Lu, X. P.; Leys, C.

2010-10-01

178

Effects of water addition on OH radical generation and plasma properties in an atmospheric argon microwave plasma jet  

SciTech Connect

Water vapor was added to the feeding gas of a continuous atmospheric argon (Ar) microwave plasma jet to study its influence on plasma shape, plasma gas temperature, and OH radical concentrations. The plasma jet was created by a 2.45 GHz microwave plasma source operating at constant power of 104 W with H{sub 2}O-Ar mixture flow rate of 1.7 standard liter per minute (slm). With an increase in the H{sub 2}O/Ar ratio from 0.0 to 1.9%, the plasma jet column length decreased from 11 mm to 4 mm, and the plasma jet became unstable when the ratio was higher than 1.9%; elevation of plasma gas temperature up to 330 K was observed in the plasma temperature range of 420-910 K. Optical emission spectroscopy showed that the dominant plasma emissions changed from N{sub 2} in the pure Ar plasma jet to OH with the addition of water vapor, and simulations of emission spectra suggested non-Boltzmann distribution of the rotational levels in the OH A-state (v'=0). Spatially resolved absolute OH number densities along the plasma jet axis were measured using UV cavity ringdown spectroscopy of the OH (A-X) (0-0) band in the H{sub 2}O/Ar ratio range of 0.0-1.9%. The highest OH number density is consistently located in the vicinity of the plasma jet tip, regardless of the H{sub 2}O/Ar ratio. OH number density in the post-tip region follows approximately an exponential decay along the jet axis with the fastest decay constant of 3.0 mm in the H{sub 2}O/Ar ratio of 1.5%. Given the low gas temperature of 420-910 K and low electron temperature of 0.5-5 eV along the jet axis, formation of the OH radical is predominantly due to electron impact induced dissociation of H{sub 2}O and dissociative recombination of H{sub 2}O{sup +} resulting from the Penning ionization process.

Srivastava, Nimisha; Wang Chuji [Department of Physics and Astronomy and the Energy Institute, Mississippi State University, Mississippi State, Mississippi 39762 (United States)

2011-09-01

179

Secondary electron emission induced by fast argon neutrals and its effects on rf plasmas  

NASA Astrophysics Data System (ADS)

In this paper we have examined a dual-frequency rf discharge in argon that is strongly affected by the secondary emission of electrons from the electrodes. We have used implicit ``Particle In Cell'' code as a tool for investigation of different electrode surface conditions that define the secondary emission. For precise description of the secondary emission we use analytic formulas suggested by Phelps and Petrovic (Plasma Sources Sci. Technol 8, R21, 1999). Two surface conditions, atomically ``clean'' and ``dirty,'' describe the secondary emission as a function of the energy of impacting ion or atom on the electrode. In dual-frequency discharges one of the electrodes usually has some voltage bias, thus leading to greater production of fast neutrals on its side. Since on the biased electrode ion and neutral fluxes are greater than on the powered electrode, the secondary emission from biased electrode has a greater effect on the plasma. Results from our simulations show that secondary emitting fast neutrals can greatly affect the plasma, especially in discharges with intense production of neutrals in the sheath. We conclude that for precise description of rf discharges a realistic modeling of the secondary emission induced by ions and fast neutrals is necessary.

Bojarov, Aleksandar; Radmilovic-Radjenovic, Marija; Petrovic, Zoran Lj.

2012-10-01

180

Acetylene - Argon Plasmas Measured at a Biased Substrate Electrode for Diamond-Like Carbon Deposition. Part 2: Ion Energy Distributions  

Microsoft Academic Search

Ion energy distributions have been determined at the rf-bias electrode in an inductively-coupled acetylene-argon plasma for various substrate bias voltages and frequencies under conditions suitable for film deposition. These are compared with those obtained at the grounded wall of a capacitively coupled plasma. In the former, for pressures up to 25 mTorr, the IEDs exhibit bimodal structures with peak separation

A. Baby; C. M. O. Mahony; P. Lemoine; P. D. Maguire

2008-01-01

181

Development and characterization of a 9-mm inductively coupled argon plasma (ICP) source for atomic emission spectrometry  

Microsoft Academic Search

A new 9-mm (i.d.) inductively coupled plasma torch is described which supports a stable, analytically useful plasma at less than 500 watts of r.f. power and 7 L\\/min total argon gas flow. Detection limits, working curves and other analytical characteristics of the new device are compared with those of both a miniature (13-mm i.d.) and conventional (19-mm i.d.) ICP. Although

A. D. Weiss; R. N. Savage; G. M. Hieftje

1980-01-01

182

Development and characterization of a 9-mm inductively coupled argon plasma (ICP) source for atomic emission spectrometry. Interim technical report  

Microsoft Academic Search

A new 9-mm (i.d.) inductively coupled plasma torch is described which supports a stable, analytically useful plasma at less than 500 watts of r.f. power and 7 L\\/min total argon gas flow. Detection limits, working curves and other analytical characteristics of the new device are compared with those of both a miniature (13-mm i.d.) and conventional (19-mm i.d.) ICP. Although

A. D. Weiss; R. N. Savage; G. M. Hieftje

1980-01-01

183

Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering  

Microsoft Academic Search

Gas-temperature and velocity profiles at the exit plane of a thermal argon plasma torch have been determined directly from a high-resolution Doppler-shifted line-shape analysis of laser light scattered by the plasma. Peak temperature and velocity values observed were 13 350 K[plus minus]7% and 1100 m s[sup [minus]1][plus minus]3%. Velocities as low as 45 m s[sup [minus]1][plus minus]45% were measured in

S. C. Snyder; L. D. Reynolds; G. D. Lassahn; J. R. Fincke; C. B. Jr. Shaw; R. J. Kearney

1993-01-01

184

Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering  

Microsoft Academic Search

Gas-temperature and velocity profiles at the exit plane of a thermal argon plasma torch have been determined directly from a high-resolution Doppler-shifted line-shape analysis of laser light scattered by the plasma. Peak temperature and velocity values observed were 13 350 K+\\/-7% and 1100 m s-1+\\/-3%. Velocities as low as 45 m s-1+\\/-45% were measured in the fringe of the jet.

S. C. Snyder; L. D. Reynolds; G. D. Lassahn; J. R. Fincke; C. B. Shaw Jr.; R. J. Kearney

1993-01-01

185

Development and characterization of a 9-mm inductively coupled argon plasma (ICP) source for atomic emission spectrometry. Interim technical report  

SciTech Connect

A new 9-mm (i.d.) inductively coupled plasma torch is described which supports a stable, analytically useful plasma at less than 500 watts of r.f. power and 7 L/min total argon gas flow. Detection limits, working curves and other analytical characteristics of the new device are compared with those of both a miniature (13-mm i.d.) and conventional (19-mm i.d.) ICP. Although temperatures of the new plasma are somewhat lower than those in the larger plasmas, the new system offers promise for future, miniaturized ICP instruments.

Weiss, A.D.; Savage, R.N.; Hieftje, G.M.

1980-09-30

186

Development and characterization of a 9-mm inductively coupled argon plasma (ICP) source for atomic emission spectrometry  

NASA Astrophysics Data System (ADS)

A new 9-mm (i.d.) inductively coupled plasma torch is described which supports a stable, analytically useful plasma at less than 500 watts of r.f. power and 7 L/min total argon gas flow. Detection limits, working curves and other analytical characteristics of the new device are compared with those of both a miniature (13-mm i.d.) and conventional (19-mm i.d.) ICP. Although temperatures of the new plasma are somewhat lower than those in the larger plasmas, the new system offers promise for future, miniaturized TCP instruments.

Weiss, A. D.; Savage, R. N.; Hieftje, G. M.

1980-09-01

187

Detection of Fibrinogen and Coagulation Factor VIII in Plasma by a Quartz Crystal Microbalance Biosensor  

PubMed Central

A quartz crystal microbalance (QCM) biosensor with nanogram sensitivity has been constructed through a reasonable designing and biological processing of the piezoelectric quartz crystals. Due to its highly sensitivity, real time detection and low cost, the proposed QCM biosensor has a promising potential in blood coagulation research. In the current study, the QCM biosensor was used to determine the activated partial thromboplastin time (APTT) for 120 anticoagulated plasma specimens. A good linear relationship was found in a double-logarithmic plot of APTT versus fibrinogen concentration in the range of 1.58–6.30 g/L. For factor VIII, the detection range by the QCM biosensor is 0.0185–0.111 mg/L. The QCM biosensor results were compared with those obtained by commercial optical coagulometry and a good agreement (correlation coefficient is 0.949 for fibrinogen, and 0.948 for factor VIII) was reached. Furthermore, the QCM determination can be completed within 10 min. Our study suggested that the proposed QCM biosensor could provide for more convenient and time saving operations, which may be useful in clinical situations for rapid monitoring of anticoagulant therapy using small volume (20 ?L) plasma specimens.

Yao, Chunyan; Qu, Ling; Fu, Weiling

2013-01-01

188

Bactericidal effects of non-thermal argon plasma in vitro, in biofilms and in the animal model of infected wounds.  

PubMed

Non-thermal (low-temperature) physical plasma is under intensive study as an alternative approach to control superficial wound and skin infections when the effectiveness of chemical agents is weak due to natural pathogen or biofilm resistance. The purpose of this study was to test the individual susceptibility of pathogenic bacteria to non-thermal argon plasma and to measure the effectiveness of plasma treatments against bacteria in biofilms and on wound surfaces. Overall, Gram-negative bacteria were more susceptible to plasma treatment than Gram-positive bacteria. For the Gram-negative bacteria Pseudomonas aeruginosa, Burkholderia cenocepacia and Escherichia coli, there were no survivors among the initial 10(5) c.f.u. after a 5 min plasma treatment. The susceptibility of Gram-positive bacteria was species- and strain-specific. Streptococcus pyogenes was the most resistant with 17?% survival of the initial 10(5) c.f.u. after a 5 min plasma treatment. Staphylococcus aureus had a strain-dependent resistance with 0 and 10?% survival from 10(5) c.f.u. of the Sa 78 and ATCC 6538 strains, respectively. Staphylococcus epidermidis and Enterococcus faecium had medium resistance. Non-ionized argon gas was not bactericidal. Biofilms partly protected bacteria, with the efficiency of protection dependent on biofilm thickness. Bacteria in deeper biofilm layers survived better after the plasma treatment. A rat model of a superficial slash wound infected with P. aeruginosa and the plasma-sensitive Staphylococcus aureus strain Sa 78 was used to assess the efficiency of argon plasma treatment. A 10 min treatment significantly reduced bacterial loads on the wound surface. A 5-day course of daily plasma treatments eliminated P. aeruginosa from the plasma-treated animals 2 days earlier than from the control ones. A statistically significant increase in the rate of wound closure was observed in plasma-treated animals after the third day of the course. Wound healing in plasma-treated animals slowed down after the course had been completed. Overall, the results show considerable potential for non-thermal argon plasma in eliminating pathogenic bacteria from biofilms and wound surfaces. PMID:20829396

Ermolaeva, Svetlana A; Varfolomeev, Alexander F; Chernukha, Marina Yu; Yurov, Dmitry S; Vasiliev, Mikhail M; Kaminskaya, Anastasya A; Moisenovich, Mikhail M; Romanova, Julia M; Murashev, Arcady N; Selezneva, Irina I; Shimizu, Tetsuji; Sysolyatina, Elena V; Shaginyan, Igor A; Petrov, Oleg F; Mayevsky, Evgeny I; Fortov, Vladimir E; Morfill, Gregor E; Naroditsky, Boris S; Gintsburg, Alexander L

2010-09-09

189

Evidence of weak plasma series resonance heating in the H-mode of neon and neon/argon inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

Phase-resolved optical emission spectroscopy measurements in argon and neon inductively coupled plasmas (ICPs) have revealed a surplus of high-energy electrons in neon-containing plasmas. Differences between results of emission model analyses using neon and argon lines (as well as probe measurements) also indicate a high-energy enhancement in neon-containing plasmas. The abundance of these extra high-energy electrons is correlated with the sheath thickness near the rf antenna and can be reduced by either adding a Faraday shield (external shielding) or increasing the plasma density. A comparison of modelled and experimental values of the 13.56 MHz time modulation of select neon emission lines strongly suggests plasma series resonance heating adjacent to the ICP antenna as the source of the extra heating.

Boffard, John B.; Jung, R. O.; Lin, Chun C.; Aneskavich, L. E.; Wendt, A. E.

2012-09-01

190

Volatilization of refractory compound forming elements from a graphite electrothermal atomization device for sample introduction into an inductively coupled argon plasma  

Microsoft Academic Search

The use of a halocarbon\\/argon atmosphere in the sampling manifold of a graphite rod electrothermal vaporization device employed for the introduction of samples into a high-frequency, inductively coupled argon plasma source for optical emission spectroscopy is shown to permit sensitive determination of elements such as boron, molybdenum, zirconium, chromium, and tungsten which form refractory oxides or carbides which limit attainable

G. F. Kirkbright; R. D. Snook

1979-01-01

191

Collateral Tissue Damage by Several Types of Coagulation (Monopolar, Bipolar, Cold Plasma and Ultrasonic) in a Minimally Invasive, Perfused Liver Model  

PubMed Central

Hemostasis in minimally invasive surgery causes tissue damage. Regardless of the method of production of thermal energy, a quick and safe coagulation is essential for its clinical use. In this study we examined the tissue damage in the isolated perfused pig liver using monopolar, bipolar, cold plasma, and ultrasonic coagulation. In a minimally invasive in vitro setup, a 2-3?cm slice of the edge of the perfused pig liver was resected. After hemostasis was achieved, liver tissue of the coagulated area was given to histopathological examination. The depth of tissue necrosis, the height of tissue loss, and the time until sufficient hemostasis was reached were analyzed. The lowest risk for extensive tissue damage could be shown for the bipolar technique, combined with the highest efficiency in hemostasis. Using cold plasma, coagulation time was longer with a deeper tissue damage. Monopolar technique showed the worst results with the highest tissue damage and a long coagulation time. Ultrasonic coagulation was not useful for coagulation of large bleeding areas. In summary, bipolar technique led to less tissue damage and best coagulation results in our minimally invasive model. These results could be important to recommend bipolar coagulation for clinical use in minimally invasive surgery.

Carus, Thomas; Rackebrandt, Klaas

2011-01-01

192

Hot-filament discharge plasma in argon gas at 140 K  

NASA Astrophysics Data System (ADS)

A hot-filament discharge plasma has been created in a double-walled vacuum chamber with the inner wall cooled by liquid nitrogen vapor. The inner brass chamber (16 cm dia. x 30 cm) is wound with copper tubing for cooling. This chamber has two tungsten filaments 10 cm in length oriented axially about 2.5 cm from the wall. Plasma measurements are made using a Pt wire probe. At 300 K, 0.6 mTorr argon in the outer chamber, and 2 mA emission, the electron density is 1 x10^8 cm-3 and the electron temperature is 0.054 eV. At 140 K, the density is 1.6 x10^8 cm-3 and their temperature is 0.11 eV confirming that the electrons are not cooled by elastic collisions with the gas. The floating potential of the probe is -2.4 V at 300 K and -0.6 V at 140 K as a consequence of the ion current to the probe being about doubled at the lower temperature. The higher ion current may be a consequence of charge-exchange collisions producing cold ions that are more easily captured by the probe. These collisions decrease the ion losses to the wall by slowing ions accelerated by the plasma potential. Electron losses are reduced because of the requirement of quasineutrality, thus reduced evaporative cooling of electrons may be the cause of the increased electron temperature in 140 K gas.

Dickson, Shannon; Robertson, Scott

2009-11-01

193

E-H mode transition in low-pressure inductively coupled nitrogen-argon and oxygen-argon plasmas  

SciTech Connect

This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N{sub 2}-Ar and O{sub 2}-Ar discharges using rf-compensated Langmuir probe measurements and optical emission spectroscopy (OES). As the ICP power increases, the emission intensities from plasma species, the electron density, the electron temperature, and the plasma potential exhibit sudden changes. The Ar content in the gas mixture and total gas pressure have been varied in an attempt to fully characterize the plasma parameters. With these control parameters varying, the changes of the transition threshold power and the electron energy distribution function (EEDF) are explored. In N{sub 2}-Ar and O{sub 2}-Ar discharges at low-pressures of several millitorr, the transition thresholds are observed to decrease with Ar content and pressure. It is observed that in N{sub 2}-Ar plasmas during the transition, the shape of the EEDF changes from an unusual distribution with a flat hole near the electron energy of 3 eV in the E mode to a Maxwellian distribution in the H mode. However, in O{sub 2} -Ar plasmas, the EEDFs in the E mode at low Ar contents show roughly bi-Maxwellian distributions, while the EEDFs in the H mode are observed to be nearly Maxwellian. In the E and H modes of O{sub 2}-Ar discharges, the dissociation fraction of O{sub 2} molecules is estimated using optical emission actinometry. During the E-H mode transition, the dissociation fraction of molecules is also enhanced.

Lee, Young Wook; Lee, Hye Lan; Chung, T. H. [Department of Physics, Dong-A University, Busan 604-714 (Korea, Republic of)

2011-06-01

194

Comparison of surface plasmon resonance and quartz crystal microbalance in the study of whole blood and plasma coagulation  

Microsoft Academic Search

The coagulation of blood plasma and whole blood was studied with a surface plasmon resonance (SPR) based device and a quartz crystal microbalance instrument with energy dissipation detection (QCM-D). The SPR and QCM-D response signals were similar in shape but differing in time scales, reflecting differences in detection mechanisms. The QCM-D response time was longer than SPR, as a physical

Trine P. Vikinge; Kenny M. Hansson; Pär Sandström; Bo Liedberg; Tomas L. Lindahl; Ingemar Lundström; Pentti Tengvall; Fredrik Höök

2000-01-01

195

Plasma antigen levels of thrombin-activatable fibrinolysis inhibitor did not differ in patients with or without disseminated intravascular coagulation  

Microsoft Academic Search

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a carboxypeptidase that downregulates fibrinolysis and might play some roles in the pathogenesis of disseminated intravascular coagulation (DIC). We prospectively examined the plasma TAFI antigen levels in patients highly suspected to be suffering from DIC. Patients were subdivided into overt DIC and non-DIC groups according to a DIC scoring system. The Sepsis-related Organ Failure Assessment

Chih-Cheng Chen; Kuan-Der Lee; Jyh-Pyng Gau; Yuan-Bin Yu; Jie-Yu You; Su-Chung Lee; Hui-Chi Hsu; Wing-Keung Chau; Chao-Hung Ho

2005-01-01

196

FAST TRACK COMMUNICATION: The influence of C2H2 and dust formation on the time dependence of metastable argon density in pulsed plasmas  

NASA Astrophysics Data System (ADS)

Diode laser absorption at 772.38 nm is used to measure the time resolved density of Ar* (3P2) metastable atoms in a capacitively coupled radio-frequency (RF) discharge running in an argon/acetylene mixture at 0.1 mbar. The RF power is pulsed at 100 Hz and the density of Ar* (3P2) atoms in the 5 ms ON time and in the afterglow is recorded. Different plasma conditions, namely (1) pure argon, (2) argon +7% acetylene before powder formation, (3) argon +7% acetylene after dust particles have been formed and (4) argon with dust particles remaining in the plasma volume but without acetylene, are studied. The measured steady-state Ar* (3P2) density in the middle of the reactor is always about 10 times larger in the dusty argon plasma than in the pure argon discharge. This is mainly a consequence of the enhancement of electron temperature after dust formation. Both steady-state densities and decay times in the afterglow indicate that the degree of dissociation of C2H2 in the plasma volume can be as high as 99%. It is shown that under our plasma conditions, the loss of Ar* (3P2) atoms on the surface of dust particles is negligible compared to their loss by diffusion to the electrodes.

Stefanovi?, Ilija; Sadeghi, Nader; Winter, Jörg

2010-04-01

197

Rapid determination of blood coagulation factor XIII activity using protein arrays for serodiagnosis of human plasma.  

PubMed

We developed a novel on-chip assay using protein arrays for quantitative and rapid analysis of blood coagulation factor XIII (FXIII) activity in human plasma. FXIII is activated by concerted action of thrombin and Ca(2+) and plays essential roles in hemostasis, angiogenesis, and wound healing. We fabricated protein arrays by immobilizing fibrinogen onto the 3-aminopropyltrimethoxysilane layer of well-type arrays and determined FXIII activity by analyzing biotinylated fibrinogen with Cy3-conjugated streptavidin. We determined optimal concentrations of Ca(2+), thrombin, and 5-(biotinamido)pentylamine (BAPA) for the on-chip activity assay, and the detection limit was 0.01 Lowey U/mL (9.9 pM). Using the on-chip activity assay, hepatocellular carcinoma patients (n = 24), but not hepatitis (n = 24) or liver cirrhosis patients (n = 41), had significantly lower FXIII activities (p < 0.001) than normal individuals (n = 41), indicating that FXIII activity is a possible diagnostic marker for hepatocellular carcinoma. In addition, we have successfully used this activity assay to reveal individual variations (37-57%, n = 65) in the inhibition rate of FXIII activity by isoniazid, the first-line antituberculosis agent. Thus, our optimized on-chip FXIII activity assay provides a quantitative and high-throughput approach to investigating the role(s) of FXIII in human diseases. Moreover, it has a strong potential to be applied toward FXIII-related personalized medicines. PMID:21323342

Kwon, Mi-Hye; Kong, Deok-Hoon; Jung, Se-Hui; Suh, In-Bum; Kim, Young-Myeong; Ha, Kwon-Soo

2011-02-16

198

Experimental studies of transverse metastable ion velocity distribution functions in the presheath of a weakly collisional argon plasma  

SciTech Connect

Laser-induced fluorescence measurements of the transverse metastable ion velocity distribution function near a negatively biased plate in a low temperature (T{sub e}<1 eV), low pressure (p{sub 0}<1 mTorr) dc multi-dipole argon discharge plasma have been made with a diode laser. The metastable argon ions in the 3s{sup 2}3p{sup 4}({sup 3}P)3d{sup 4}F{sub 7/2} state are found to be characterized by a Maxwellian temperature transverse to the direction normal to the plate. For a neutral pressure of 0.3 mTorr, the transverse temperature increases along the presheath from 0.026 eV in the bulk plasma to 0.058 eV at the presheath sheath boundary.

Lee, Dongsoo; Hershkowitz, Noah [Department of Engineering Physics, University of Wisconsin at Madison, Madison, Wisconsin 53706 (United States); Severn, Greg [Department of Physics, University of San Diego, San Diego, California 92110 (United States)

2008-08-15

199

Treatment of inherited coagulation disorders  

Microsoft Academic Search

Inherited coagulation protein deficiencies associated with bleeding diatheses may present with spontaneous bleeding early in life, or may not be recognized until the development of hemorrhage after trauma or surgery. Diagnostic evaluation with coagulation screening tests, followed by confirmation with coagulation factor assays, is essential for appropriate management. For moderate-to-severe hemophilia, treatment includes coagulation factor replacement with purified, plasma-derived coagulation

Alice J. Cohen; Craig M. Kessler

1995-01-01

200

The Activation of the Contact Phase of Coagulation by Physiologic Surfaces in Plasma: The Effect of Large Negatively Charged Liposomal Vesicles  

Microsoft Academic Search

The endogenous. negatively charged surface that induces activation of the contact coagulation factors was investi- gated in plasmas taken from women in late pregnancy and control subjects of child-bearing age. The plasmas from the two groups of subjects were incubated at 4#{176}C for 24 hours either in plastic or in glass tubes and the factor VII coagulant activity (VlIc) was

K. A. Mitropoulos; J. C. Martin; B. E. A. Reeves; M. P. Esnouf

201

Acetylene - Argon Plasmas Measured at a Biased Substrate Electrode for Diamond-Like Carbon Deposition. Part 2: Ion Energy Distributions  

Microsoft Academic Search

Ion energy distributions have been determined at the rf-bias electrode in an\\u000ainductively-coupled acetylene-argon plasma for various substrate bias voltages\\u000aand frequencies under conditions suitable for film deposition. These are\\u000acompared with those obtained at the grounded wall of a capacitively coupled\\u000aplasma. In the former, for pressures up to 25 mTorr, the IEDs exhibit bimodal\\u000astructures with peak separation

A. Baby; C. M. O. Mahony; P. Lemoine; P. D. Maguire

2008-01-01

202

Determination of rare earth elements in geological materials by inductively coupled argon plasma\\/atomic emission spectrometry  

Microsoft Academic Search

Inductively coupled argon plasma\\/optical emission spectrometry (ICAP\\/OES) is useful as a simultaneous, multielement analytical technique for the determination of trace elements in geological materials. A method for the determination of trace-level rare earth elements (REE) in geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved

J. G. Crock; F. E. Lichte

1982-01-01

203

Improvement in micro-structural and mechanical properties of zinc film by surface treatment with low temperature argon plasma  

Microsoft Academic Search

Nanocrystalline zinc films were deposited on gold coated borosilicate glass substrates by thermal evaporation method using zinc powders as the source material and then treated with argon plasma at various temperatures. From X-ray diffraction study, the as-deposited films are found to be metallic Zn and polycrystalline in nature. The crystalline nature improves with the increase of temperature up to 200°C

Debadhyan Behera; Dilip K Mishra; Siddhartha K Pradhan; Ramasamy Sakthivel; Swagatika Mohanty

2011-01-01

204

Introduction of sulfate groups on poly(ethylene) surfaces by argon plasma immobilization of sodium alkyl sulfates  

Microsoft Academic Search

Sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by immobilizing a precoated layer of either sodium 10-undecene sulfate (S11(:)) or sodium dodecane sulfate (SDS) on the polymeric surface by means of an argon plasma treatment. For this purpose, S11(:) was synthesized by sulfating 10-undecene-1-ol using the pyridine-SO3 complex. The presence of sulfate groups at

J. P. Lens; J. G. A. Terlingen; G. H. M. Engbers; J. Feijen

1998-01-01

205

Effective collision cross section of xenon plasma debris in argon buffer gas  

NASA Astrophysics Data System (ADS)

Mitigation of fast debris and soft x-rays generated from laser-produced xenon plasmas were studied in an argon buffer gas in laser intensities of 109-1011 W cm-2 using a cryogenic drum target. Considerable mitigation of debris was confirmed by measurements of material sputtering. From the experimental results, an attenuation parameter of sputtering by the debris \\bar \\sigma _1 and an absorption cross section of soft x-rays at 13.5 nm ?2(13.5?nm) were derived to be 2.2 × 10-20 m2 and 1.8 × 10-22 m2, respectively. Moreover, \\bar \\sigma _1 is concluded to be equivalent to the effective collision cross section ?1 of a debris particle at kinetic energy of 1-4 keV. Sufficient debris mitigation can be obtained together with low soft x-ray absorption (less than 10%). These parameters provide a useful design tool for realizing a practical soft x-ray source because they predict the effect of the buffer gas well.

Inoue, Tomoaki; Mochizuki, Takayasu; Masuda, Kazuya; Amano, Sho; Sekioka, Tsuguhisa; Kanda, Kazuhiro

2012-06-01

206

Development of a fluorescent method for detecting the onset of coagulation in human plasma on microstructured lateral flow platforms.  

PubMed

Microfluidic devices and microsystems have been used to develop blood coagulation monitoring devices for point of care diagnostic use. However, many of them suffer from inherent variability and imprecision, partly due to the fact that they only detect changes in bulk clotting properties and do not reflect the microscopic nature of blood coagulation. This work demonstrates microstructured lateral flow platforms used in combination with fluorescently labelled fibrinogen to detect microscopic clot formation. Plasma samples applied to platforms modified with coagulation activation reagents and fluorescent fibrinogen produced changes in fluorescence intensity due to incorporation of the fluorophore into the forming microclots. It was found that the change in the distribution of the fluorescence within the sample over time was an excellent predictor of the onset of coagulation, which could be used to determine the clotting time. The impact of various assay parameters was optimised and the assay was shown to be capable of measuring the effect of heparin concentration on blood clotting time from 0 to 1.5 U mL(-1). PMID:21293802

Dudek, Magdalena M; Kent, Nigel J; Gu, Pan; Fan, Z Hugh; Killard, Anthony J

2011-02-04

207

Conversion of emitted dimethyl sulfide into eco-friendly species using low-temperature atmospheric argon micro-plasma system.  

PubMed

A custom-made atmospheric argon micro-plasma system was employed to dissociate dimethyl sulfide (DMS) into a non-foul-smelling species. The proposed system takes the advantages of low energy requirement and non-thermal process with a constant flow rate at ambient condition. In the experiments, the compositions of DMS/argon plasma, the residual gaseous phases, and solid precipitates were respectively characterized using an optical emission spectrometer, various gas-phase analyzers, and X-ray photoemission spectroscopy. For 400 ppm DMS introduced into argon plasma with two pairs of electrodes (90 W), a complete decomposition of DMS was achieved; the DMS became converted into excited species such as C, C(2), H, and CH. When gaseous products were taken away from the treatment area, the excited species tended to recombine and form stable compounds or species, which formed as solid particles and gaseous phases. The solid deposition was likely formed by the agglomeration of C-, H-, and S-containing species that became deposited on the quartz inner tube. For the residual gaseous phases, low-molecular-weight segments mostly recombined into relatively thermodynamic stable species, such as hydrogen, hydrogen sulfide, and carbon disulfide. The dissociation mechanism and treatment efficiency are discussed, and a treatment of converting DMS into H(2)-, CS(2)-, and H(2)S-dominant by-products is proposed. PMID:22172460

Chen, Hsin-Hung; Weng, Chih-Chiang; Liao, Jiunn-Der; Whang, Liang-Ming; Kang, Wei-Hung

2011-11-28

208

Assessment of the roles of various inactivation agents in an argon-based direct current atmospheric pressure cold plasma jet  

SciTech Connect

Three types of gases, pure argon (99.999%), argon with 2% oxygen, and argon with 2% oxygen and 10% nitrogen were used as operating gases of a direct current atmospheric pressure cold plasma jet to inactivate Staphylococcus aureus (S. aureus) suspended in a liquid. The inactivation efficacies for the plasma jets operating in the three gases decrease from Ar/O{sub 2}(2%) to Ar/O{sub 2}(2%)/N{sub 2}(10%) to pure Ar. Optical emission spectroscopy, electron spin resonance spectroscopy, high performance liquid chromatography, and atomic absorption spectrophotometry were employed to identify and monitor the reactive species in the plasma-liquid system for the three operating gases and revealed the presence of O, {sup 1}O{sub 2}, OH, NO, H{sub 2}O{sub 2}, O{sub 3}, and NO{sub 3}{sup -}/NO{sub 2}{sup -} as well as Cu{sup +}/Cu{sup 2+}. The S. aureus inactivation results indicate that atomic oxygen (O) is the key inactivation agent, while other species play a lesser role in the inactivation progress studied here.

Zhang Qian; Wang Ruixue [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Sun Peng; Feng Hongqing; Liang Yongdong [College of Engineering, Peking University, Beijing 100871 (China); Zhu Weidong [Department of Applied Science and Technology, Saint Peter's College, New Jersey 07031 (United States); Becker, Kurt H. [Department of Applied Physics, Polytechnic Institute of New York University, New York 11201 (United States); Zhang Jue; Fang Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

2012-06-15

209

Lineshape Analysis of Laser Light Scattered by AN Argon Thermal Plasma Jet  

NASA Astrophysics Data System (ADS)

Radial gas temperature and velocity profiles in the exit plane of an atmospheric pressure argon thermal plasma jet were determined from high resolution lineshape analysis of elastically scattered laser light. Unlike emission spectroscopy, lineshape analysis of scattered laser light does not rely on assumptions of local thermodynamic equilibrium (LTE) or specific non-LTE models to measure gas or kinetic temperature, and has a high degree of spatial resolution. At atmospheric pressure, if electron densities are > 10^{22} m^{-3}, coherent Thomson scattering dominates, while at lower electron densities, Rayleigh scattering dominates. Using a frequency doubled injection-seeded Nd:YAG laser and a scanning tandem Fabry-Perot interferometer, high quality lineshapes were measured in the exit plane of a commercial subsonic plasma torch at several radial positions with torch operating currents ranging from 300 to 900 A. The experimental lineshapes were fitted by the lineshape theory and the gas temperatures determined. The scattered wavevector had a component along the flow axis of the jet resulting in a Doppler shift of the frequency of scattered light relative to the frequency of the incident laser. From this Doppler shift the gas velocity was calculated. Maximum centerline temperature and velocity values observed were 13350 K +/- 7% and 100 m s ^{-1} +/- 3%. The fitting errors for the centerline lineshape data were 2-3% for all operating currents. The minimum velocity measured in the fringe of the jet was 45 m s^ {-1} +/- 45%. Comparison of temperature profiles calculated from the lineshape data with temperatures determined from LTE emission spectroscopy shows a severe departure from LTE in the outer regions of the jet. Centerline temperature and velocity values determined from lineshape analysis of scattered light increase with torch operating current to about 600 A after which they remain essentially constant. However, spectroscopic measurements show that the electron temperature and density continue to increase with current. This indicates that increasing the electrical power dissipated by the torch drives the plasma away from LTE. Measured radial velocity profiles are very nearly parabolic and differ significantly from velocity profiles assumed by computational modelers as boundary conditions for models of the plasma jet.

Snyder, Stuart Cody

210

Lineshape analysis of laser light scattered by an argon thermal plasma jet  

NASA Astrophysics Data System (ADS)

Radial gas temperature and velocity profiles in the exit plane of an atmospheric pressure argon thermal plasma jet were determined from high resolution lineshape analysis of elastically scattered laser light. Unlike emission spectroscopy, lineshape analysis of scattered laser light does not rely on assumptions of local thermodynamic equilibrium (LTE) or specific non-LTE models to measure gas or kinetic temperature, and has a high degree of spatial resolution. At atmospheric pressure, if electron densities are greater than 10(exp 22) m(exp -3), coherent Thomson scattering dominates, while at lower electron densities, Rayleigh scattering dominates. Using a frequency doubled injection-seeded Nd:YAG laser and a scanning tandem Fabry-Perot interferometer, high quality lineshapes were measured in the exit plane of a commercial subsonic plasma torch at several radial positions with torch operating currents ranging from 300 to 900 A. The experimental lineshapes were fitted by the lineshape theory and the gas temperatures determined. The scattered wavevector had a component along the flow axis of the jet resulting in a Doppler shift of the frequency of scattered light relative to the frequency of the incident laser. From this Doppler shift the gas velocity was calculated. Maximum centerline temperature and velocity values observed were 13350 K plus or minus 7 percent and 100 m/s plus or minus 3 percent. The fitting errors for the centerline lineshape data were 2-3 percent for all operating currents. The minimum velocity measured in the fringe of the jet was 45 m/s plus or minus 45 percent. Comparison of temperature profiles calculated from the lineshape data with temperatures determined from LTE emission spectroscopy shows a severe departure from LTE in the outer regions of the jet. Centerline temperature and velocity values determined from lineshape analysis of scattered light increase with torch operating current to about 600 A after which they remain essentially constant. However, spectroscopic measurements show that the electron temperature and density continue to increase with current. This indicates that increasing the electrical power dissipated by the torch drives the plasma away from LTE. Measured radial velocity profiles are very nearly parabolic and differ significantly from velocity profiles assumed by computational modelers as boundary conditions for models of the plasma jet.

Snyder, Stuart Cody

211

Discharge characteristics of an atmospheric-pressure argon plasma column generated with a single-electrode configuration  

SciTech Connect

An atmospheric-pressure argon discharge plasma column is generated by making use of a single-electrode configuration with the power supply operating at a frequency of 45 kHz. It is observed that corona, glowlike plume, and filamentary discharges evolve individually with increasing applied voltage. It is in the filamentary state with average electron density of order 10{sup 12} cm{sup -3} that plasma column grows up in the tube with increasing applied voltage. Its discharge characteristics are determined by measuring electrical parameters (voltage, conduction current, and average absorbed power) and optical emission spectroscopy.

Li Shouzhe; Huang Wentong; Zhang Jialiang; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2009-07-15

212

Measurements of electron temperature and argon metastable density by measuring optical emission in inductively coupled plasma.  

NASA Astrophysics Data System (ADS)

To obtain electron temperatures and argon metastable number densities at various powers (100 W to 1 kW) and pressures (2 mTorr to 20 mTorr), a spectroscopic method [1] is used. The method is based on the availability of experimental relative emission intensities of only four argon lines that originate from 4p argon levels. Electron temperatures measured by the optical emission lines are compared with those by a Langmuir probe. They were in close agreement. Furthermore, the metastable densities from the model were estimated and presented. [1] D. Mariotti, Y Shimizu, T. Sasaki, N. Koshizaki, Appl. Phys. Lett. 89, 201502 (2006)

Lee, Young-Kwang; Hwang, Kwang-Tae; Lee, Min-Hyong; Chung, Chin-Wook

2007-10-01

213

Three-electrode direct current argon plasma: studies in discrete sample introduction, mathematical correction of drifted plasma data, and organic solvent introduction effects in the plasma  

SciTech Connect

This thesis investigates three areas of research with the three-electrode direct-current argon plasma(DCP). The first area examines discrete sample introduction into the DCP. Discrete sampling, well known for its sample conservation advantage, has been used with flame atomic absorption and inductively coupled plasma emission spectroscopies but no work has been published on using this sampling mode with the DCP. Discrete sample introduction is compared here to the standard continuous sampling mode. An unique sample drop generator is described and characterized. Results are given for a variety of system effects and used to explain the effect of sample drop size on emission intensity. The second area of research involves the use of mathematical correction techniques for removing the effect of plasma emission drift from analytical data. The introduction of hydrophobic samples into the DCP is the last area examined in this thesis. Organic matrices are routinely run on the DCP but they can be prone to little understood matrix interferences effects. A modified sample introduction chimney was designed that largely eliminated the carbon buildup encountered with the standard chimney permitting extensive studies using organic solvent with the plasma. It was found that the analytical emission zone of the plasma appears to be spatially tied to the plasma core.

Boyko, W.J.

1985-01-01

214

Characterization of an inductively coupled nitrogen-argon plasma by Langmuir probe combined with optical emission spectroscopy  

SciTech Connect

The properties of low-pressure inductively coupled nitrogen-argon plasmas were investigated by using a Langmuir probe combined with optical emission spectroscopy (OES) under the conditions of pressures in the range of 1-30 mTorr and applied rf powers of 200-600 W. In the experiments, the argon was introduced as an actinometer and as an adding gas. The effect of the argon content in the gas mixture was examined in the range of 5%-80%. The electron energy probability function (EEPF), the electron density, and the electron temperature were obtained by using an rf-compensated Langmuir probe. The dissociation fractions were obtained from the OES actinometry. The electron temperature was also obtained by OES corona model and compared with that measured by the probe. The second positive and first negative systems of spectral bands from nitrogen molecules were analyzed to estimate the vibrational and rotational temperatures. The effects of the control parameters on the plasma parameters and dissociation fraction were investigated. While the calculated nitrogen atom density increased with power, it exhibited a maximum value near the Ar content of 30%.

Song, M. A.; Lee, Y. W.; Chung, T. H. [Department of Physics, Dong-A University, Busan 604-714 (Korea, Republic of)

2011-02-15

215

Study of Longitudinal Distribution of Ne I Line Radiation in Plasmas Produced in Wall-Stabilized D.C. Arcs Applying Argon and Helium as Working Gases  

SciTech Connect

The distributions of plasma parameters in plasmas containing different admixtures of neon have been studied. As a working gas (main plasma component) argon as well as helium have been applied. In both cases the admixture of neon changes the plasma parameters. The demixing effect causes ununiform axial distribution of neon and consequently side effects in form of axial gradients of plasma temperature and electron density.

Ksiazdotek, I. [Institute of Physics, Opole University, ul. Oleska 48, 45-052 Opole, Poland, (Poland)

2008-03-19

216

Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Microbial biofilms are a functional matrix of microbial cells, enveloped in polysaccharides, enzymes and virulence factors secreted by them that can develop on indwelling medical devices and biomaterials. Plasma sterilization has been widely studied in recent years for biological applications. In this study, we evaluated the possibility of removal and anti-recovery of biofilms by microwave-induced argon plasma at atmospheric pressure. We observed that all bacterial biofilms formatted by Gram-negative and Gram-positive bacteria are removed in less than 20 s, and the growth inhibitions of planktonic bacteria within biofilms are also confirmed by plasma exposure for 5 s. These results suggest that our plasma system can be applied to medical and biological fields where the removal of biofilms and their debris is required.

Lee, Mi Hee; Park, Bong Joo; Jin, Soo Chang; Kim, Dohyun; Han, Inho; Kim, Jungsung; Hyun, Soon O.; Chung, Kie-Hyung; Park, Jong-Chul

2009-11-01

217

Time-dependent effects of low-temperature atmospheric-pressure argon plasma on epithelial cell attachment, viability and tight junction formation in vitro  

NASA Astrophysics Data System (ADS)

The application of physical plasma to living tissues is expected to promote wound healing by plasma disinfection and stimulation of tissue regeneration. However, the effects of plasma on healthy cells must be studied and understood. In our experiments we used an argon plasma jet (kINPen®09) to gain insights into time-dependent plasma effects on cell attachment, viability and tight junction formation in vitro. Murine epithelial cells mHepR1 were suspended in complete cell culture medium and were irradiated with argon plasma (direct approach) for 30, 60 and 120 s. Suspecting that physical plasma may exert its effect via the medium, cell culture medium alone was first treated with argon plasma (indirect approach) and immediately afterwards, cells were added and also cultured for 24 h. Cell morphology and vitality were verified using light microscopy and an enzyme-linked immunosorbent assay. Already after 30 s of treatment the mHepR1 cells lost their capability to adhere and the cell vitality decreased with increasing treatment time. Interestingly, the same inhibitory effect was observed in the indirect approach. Furthermore, the argon plasma-treated culture medium-induced large openings of the cell's tight junctions, were verified by the zonula occludens protein ZO-1, which we observed for the first time in confluently grown epithelial cells.

Hoentsch, Maxi; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Nebe, J. Barbara

2012-01-01

218

Gas temperature dependence of coagulation onset times for nanoparticles in low pressure hydrocarbon plasmas  

NASA Astrophysics Data System (ADS)

Onset times for coagulation of nanoparticles in chemical reactive low pressure Ar/C2H2 and Ar/CH4 radiofrequency (rf) discharges have been measured as a function of the gas temperature while either the gas pressure or the gas density was kept constant. As a diagnostic, the phase angle between rf voltage and rf current was monitored. The results demonstrate, within the temperature range 25 °C-150 °C, that for both gases coagulation is delayed significantly (by more than a factor of 10) for increasing temperatures. These results are explained in terms of the temperature dependence of the Brownian diffusion coefficient.

Beckers, J.; Kroesen, G. M. W.

2013-09-01

219

Identification of proteins similar to Bothrops jararaca coagulation inhibitor (BjI) in the plasmas of Bothrops alternatus, Bothrops jararacussu and Crotalus durissus terrificus snakes.  

PubMed

Bothrops jararaca coagulation inhibitor (BjI), a protein isolated from B. jararaca plasma, specifically inhibits the coagulant activity of thrombin. Our group previously identified proteins similar to BjI in the plasma of other snakes [Tanaka-Azevedo, A.M., Tanaka, A.S., Sano-Martins I.S., 2003. A new blood coagulation inhibitor from the snake Bothrops jararaca plasma: isolation and characterization. Biochem Biophys Res Commun 308, 706-712.]. In the present study, we analyzed the presence of BjI-like proteins in the plasmas of three different species of viperid snakes, Bothrops alternatus, Bothrops jararacussu and Crotalus durissus terrificus. These proteins exhibited 109 and/or 138 kDa and were immunologically related to BjI. They also inhibited the coagulant activity of thrombin, evaluated by the thrombin time test. These findings demonstrate the presence of proteins similar to BjI in these three species, although such inhibitor could not be observed in all samples of the specimens tested. Moreover, the presence of these proteins in the plasma is related to prolongation of thrombin time, implying a relationship between these proteins and their inhibitory coagulant activity upon thrombin. Our results suggest that BjI-like proteins are widely distributed among Crotalinae snakes found in Brazil. PMID:17931922

de Morais, Karen Batista; Fernandes Grego, Kathleen; Tanaka-Azevedo, Anita Mitico

2007-09-20

220

Experimental study of the influence of nanoparticle generation on the electrical characteristics of argon-silane capacitive radio-frequency plasmas  

Microsoft Academic Search

The nonintrusive detection of particle contamination problems is of great interest to plasma processing in the manufacture of semiconductors. We have studied the influence of particle generation in argon-silane capacitive plasmas on the electrical discharge properties which can be nonintrusively measured with a current-voltage sensor. The Fourier components of the rf current and voltage and the respective phase angles between

Zhe Shen; Uwe Kortshagen

2002-01-01

221

The Mechanisms of Coagulation.  

ERIC Educational Resources Information Center

|Several topics such as heart disease, strokes, biochemical reactions, blood components, and genetics can be related to blood clotting. Introduces a simple, safe and inexpensive hands-on demonstration using bovine (cattle) blood plasma of normal and abnormal coagulation. (ZWH)|

Kurtz, Richard; Jesty, Jolyon

1994-01-01

222

Comparison of functional aspects of the coagulation cascade in human and sea turtle plasmas  

Microsoft Academic Search

Functional hemostatic pathways are critical for the survival of all vertebrates and have been evolving for more than 400 million years. The overwhelming majority of studies of hemostasis in vertebrates have focused on mammals with very sparse attention paid to reptiles. There have been virtually no studies of the coagulation pathway in sea turtles whose ancestors date back to the

Gerald Soslau; Bryan Wallace; Catherine Vicente; Seth J. Goldenberg; Todd Tupis; James Spotila; Robert George; Frank Paladino; Brent Whitaker; Gary Violetta; Rotney Piedra

2004-01-01

223

The effect of gas flow on argon plasma discharge generated with a single-electrode configuration at atmospheric pressure  

SciTech Connect

A long atmospheric-pressure plasma column confined in a dielectric tube is generated in argon with use of a single-electrode configuration driven with a sinusoidal power supply operating at 45 kHz. The electrical characteristics are investigated by means of measuring voltage-current and voltage-power curves at two gas flow states, turbulent and laminar. The gas temperatures of plasma discharge at various gas flow rates are determined by the spectroscopic analysis of OH A-X spectrum. The discussion about effect of gas flow on electrical discharge characteristics is presented and it is found that the heat removal by gas flow plays the most important role in determining its electrical characteristics.

Li Shouzhe; Huang Wentong; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2009-09-15

224

Continuous wave cavity ring down spectroscopy measurements of ion velocity distribution functions in argon helicon plasma  

NASA Astrophysics Data System (ADS)

The West Virginia University helicon source group routinely employs laser induced fluorescence (LIF) to measure velocity distribution functions (VDFs) of argon ions, argon neutrals, helium neutrals and xenon ions. We are developing a continuous wave cavity ring down spectroscopy (CW-CRDS) diagnostic with a narrow linewidth, tunable diode laser as an alternative technique to measure VDFs in species where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopy technique, CRDS can also provide a direct measurement of the absolute metastable state density. Here we present Ar II ion VDFs obtained through measurements of the Doppler broadened absorption spectrum of Ar II at 668.614 nm (in vacuum), a standard initial state for conventional Ar II LIF.

Chakraborty Thakur, Saikat; Carr, Jerry, Jr.; McCarren, Dustin; Galante, Matthew; Hansen, Alex; Scime, Earl

2010-11-01

225

Acetylene-argon plasmas measured at a biased substrate electrode for diamond-like carbon deposition: I. Mass spectrometry  

NASA Astrophysics Data System (ADS)

We report, for the first time, quadrupole mass spectrometry of neutral and positive ionic hydrocarbon species measured at the rf-biased substrate electrode of an inductively coupled plasma for acetylene rich C2H2 : Ar mixtures under various bias, frequency and pressure conditions. It has been observed that, irrespective of initial gas mixture, the resultant plasma is dominated by argon neutrals and ions. This is attributed to highly efficient conversion of acetylene to C2H due to the enhanced electron density compared with a standard capacitive plasma where the acetylene (neutral and ion) species remain dominant. This conversion may be crucial to film formation via inert rather than hydrocarbon ion bombardment. In addition, the transient formation of CH4 from acetylene has been discovered using IR absorption spectroscopy with time constants similar to observed pressure variations. Rate coefficients and rates for many of the reaction mechanisms, calculated using measured electron energy distribution functions and species densities, are given. These results have important application in plasma models and growth studies for hydrogenated amorphous or diamond-like carbon film deposition. Film growth under similar plasma conditions is reported in an associated paper along with ion energy distributions for important growth species. .

Baby, A.; Mahony, C. M. O.; Maguire, P. D.

2011-02-01

226

Thai national reference preparation in blood coagulation. IV. Home made reference plasma for von Willebrand's factor assay.  

PubMed

Two lots of home made reference plasma: FVIII R:Ag 30/8/88 and FVIII R:Ag 18/10/88 were prepared by lyophilization of pooled normal human plasma. Modification of J. Cejka's technique was used to determine FVIII R:Ag. This technique was tested for reliability i.e. precision, reproducibility and sensitivity. The concentration of FVIII R:Ag, determined by calibration against the 1st British Standard for FVIII R:Ag, human 66/355, which was established by National Institute for Biological Standard and Control (NIBS & C), London, the WHO International Laboratory for Biological Standard, were respectively 1.058 and 1.023 Ag units/ml for FVIII R:Ag 30/8/88 and FVIII R:Ag 18/10/88, respectively. The precision of the procedure and the accuracy of FVIII R:Ag concentration of both lots were verified by using them as standard curve to determine FVIII R:Ag in 4 unknown plasma samples, supplied by the UK Reference Laboratory for Anticoagulant Reagent & Control; WHO Collaborating Center for Quality Assessment, in Blood Coagulation Testing for International Quality Control Survey in Blood Coagulation. The results were very satisfactory. The coefficient of variation was between 2.22-5.47 per cent when compared with other 29 laboratories around the world. These home made reference preparation are stable at least up to 30 months at -70 degrees C, and can be applied for calibration of unknown sample instead of the 1st British Standard for FVIII R:Ag, human 66/355. PMID:7964228

Talalak, P; Luenee, P; Opartkiattikul, N; Sangtawisin, V

1993-10-01

227

A comparison study of improvement of binding strength of polypyrrole (PPy) coating on polyester using Argon, Oxygen and Nitrogen plasma treatment  

NASA Astrophysics Data System (ADS)

In this work, we have studied the performance of different plasma gases (Ar, N2, and O2) and the factors responsible for the improvement of binding of PPy with both polyester thin film and fabric. The plasma was generated by a radio frequency (RF) generator. The gas pressure (8x10^ -2mbar) and the RF power (100 W) were kept the same, while treatment time varied between 60 and 180 sec. Treated samples were subsequently coated with PPy. The oxygen plasma treated samples showed much more pronounced changes in the surface topography compared to nitrogen and argon plasma treated samples. The contact angle decreased from 84 for the untreated sample to 55 for Argon, 42 for nitrogen and 35 for oxygen plasma-treated samples after 120 sec treatment. Abrasion resistance and conductivity measurements suggest effectiveness of different plasma gases in the following order: O2>Ar>N2. XPS results show a decrease in C-C (284.6 eV) and an increase in C-O (286.4 eV) and O-C=O (288.7 eV) percentages for each plasma gas, while oxygen to carbon ratios for oxygen, argon and nitrogen plasma are 0.56, 0.5 and 0.46 respectively. It is concluded that improvement of binding of PPy is both due to increased surface roughness and incorporation of oxygen containing functional groups.

Mehmood, Tariq; Dai, Jane; Kouzani, Abbas; Kaynak, Akif

2011-11-01

228

A comparison study of improvement of binding strength of polypyrrole (PPy) coating on polyester using Argon, Oxygen and Nitrogen plasma treatment  

NASA Astrophysics Data System (ADS)

In this work, we have studied the performance of different plasma gases (Ar, N2, and O2) and the factors responsible for the improvement of binding of PPy with both polyester thin film and fabric. The plasma was generated by a radio frequency (RF) generator. The gas pressure (8x10-2mbar) and the RF power (100 W) were kept the same, while treatment time varied between 60 and 180 sec. Treated samples were subsequently coated with PPy. The oxygen plasma treated samples showed much more pronounced changes in the surface topography compared to nitrogen and argon plasma treated samples. The contact angle decreased from 84 for the untreated sample to 55 for Argon, 42 for nitrogen and 35 for oxygen plasma-treated samples after 120 sec treatment. Abrasion resistance and conductivity measurements suggest effectiveness of different plasma gases in the following order: O2>Ar>N2. XPS results show a decrease in C-C (284.6 eV) and an increase in C-O (286.4 eV) and O-C=O (288.7 eV) percentages for each plasma gas, while oxygen to carbon ratios for oxygen, argon and nitrogen plasma are 0.56, 0.5 and 0.46 respectively. It is concluded that improvement of binding of PPy is both due to increased surface roughness and incorporation of oxygen containing functional groups.

Mehmood, Tariq; Dai, Jane; Kouzani, Abbas; Kaynak, Akif

2011-11-01

229

The application of cold-plasma coagulation on the visceral pleura results in a predictable depth of necrosis without fistula generation  

PubMed Central

A technique for the safe transfer of electric energy to the pulmonary surface for the potential evaporation of malignant tumours is non-existent to date. By conducting the current study, we wanted to generate data on the potential beneficiary effects and complications of using cold-plasma coagulation on the pulmonary surface. Cold-plasma coagulation was applied to the pulmonary surface in eight female mini-pigs via a thoracoscopic access. After 12 days, we performed a re-thoracoscopy on the contralateral side. After a further 12 days, we performed a median sternotomy and did cold-plasma coagulation on previously untreated areas of either lung. No pulmonary fistulas were detected. In two of the eight pigs, we found a localized chronic pneumonia. None of the pigs died during the course of the study. Morbidity was also low with two pigs refusing food intake, one pig with dyspnoea after difficult intubation and one pig coughing. All events were self-limited and occurred only on post-operative Day 1. The treatment effect was almost linear and correlated to the generator energy applied. The differences between the effects reached statistical significance (P < 0.05). The application of cold-plasma coagulation to the pulmonary surface is safe in pigs. A potential clinical application of this technique is treatment of malignant pleural mesothelioma.

Hoffmann, Martin; Ulrich, Anita; Schloericke, Erik; Limmer, Stefan; Habermann, Jens Karsten; Wolken, Heike; Bruch, Hans-Peter; Kujath, Peter

2012-01-01

230

The application of cold-plasma coagulation on the visceral pleura results in a predictable depth of necrosis without fistula generation.  

PubMed

A technique for the safe transfer of electric energy to the pulmonary surface for the potential evaporation of malignant tumours is non-existent to date. By conducting the current study, we wanted to generate data on the potential beneficiary effects and complications of using cold-plasma coagulation on the pulmonary surface. Cold-plasma coagulation was applied to the pulmonary surface in eight female mini-pigs via a thoracoscopic access. After 12 days, we performed a re-thoracoscopy on the contralateral side. After a further 12 days, we performed a median sternotomy and did cold-plasma coagulation on previously untreated areas of either lung. No pulmonary fistulas were detected. In two of the eight pigs, we found a localized chronic pneumonia. None of the pigs died during the course of the study. Morbidity was also low with two pigs refusing food intake, one pig with dyspnoea after difficult intubation and one pig coughing. All events were self-limited and occurred only on post-operative Day 1. The treatment effect was almost linear and correlated to the generator energy applied. The differences between the effects reached statistical significance (P < 0.05). The application of cold-plasma coagulation to the pulmonary surface is safe in pigs. A potential clinical application of this technique is treatment of malignant pleural mesothelioma. PMID:22194274

Hoffmann, Martin; Ulrich, Anita; Schloericke, Erik; Limmer, Stefan; Habermann, Jens Karsten; Wolken, Heike; Bruch, Hans-Peter; Kujath, Peter

2011-12-22

231

Femtosecond laser ablation inductively coupled plasma mass spectrometry: Transport efficiencies of aerosols released under argon atmosphere and the importance of the focus position  

Microsoft Academic Search

Although the utilization of helium as aerosol carrier has been shown to improve both accuracy and sensitivity of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), occasionally, argon is being used due to practical and economic reasons. In order to provide more insight into the mechanisms underlying these performance differences, in this study, transport efficiencies of aerosols released by NIR-

C. C. Garcia; M. Walle; H. Lindner; J. Koch; K. Niemax; D. Gunther

2008-01-01

232

Evidence of weak plasma series resonance heating in the H-mode of neon and neon/argon inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

The shape of the electron energy distribution function (EEDF) in low-temperature plasmas governs the relative rates of electron-impact processes that determine key discharge properties. Comparison of EEDFs measured with probes and optical emission [1] in argon and neon inductively coupled plasmas (ICP) has revealed a surplus of high-energy electrons in neon-containing plasmas. The abundance of these extra high energy electrons is correlated with the sheath thickness near the rf antenna and can be reduced by either adding a Faraday shield or increasing the plasma density. These trends suggest an association of the surplus high-energy electrons with stochastic heating of electrons in capacitively-coupled electric fields in the sheath adjacent to the antenna. Conventional stochastic heating, however, is found to be insufficient to account for the EEDF observations, and a comparison of modeled and experimental values of the 13.56 MHz time modulation of select neon emission lines strongly suggests plasma series resonance (PSR) heating adjacent to the ICP antenna as the source of the extra high-energy electrons. [4pt] [1] Plasma Sources Sci. Technol. 20, (2011) 055006.

Wendt, A. E.; Boffard, John B.; Jung, R. O.; Lin, Chun C.; Aneskavich, L. E.

2012-10-01

233

The effect of surface contact activation and temperature on plasma coagulation with an RNA aptamer directed against factor IXa.  

PubMed

The anticoagulant properties of a novel RNA aptamer that binds FIXa depend collectively on the intensity of surface contact activation of human blood plasma, aptamer concentration, and its binding affinity for FIXa. Accordingly, anticoagulation efficiency of plasma containing any particular aptamer concentration is low when coagulation is strongly activated by hydrophilic surfaces compared to the anticoagulation efficiency in plasma that is weakly activated by hydrophobic surfaces. Anticoagulation efficiency is lower at hypothermic temperatures possibly because aptamer-FIXa binding decreases with decreasing temperatures. Experimental results demonstrating these trends are qualitatively interpreted in the context of a previously established model of anticoagulation efficiency of thrombin-binding DNA aptamers that exhibit anticoagulation properties similar to the FIXa aptamer. In principle, FIXa aptamer anticoagulants should be more efficient and therefore more clinically useful than thrombin-binding aptamers because aptamer binding to FIXa competes only with FX that is at much lower blood concentration than fibrinogen (FI) that competes with thrombin-binding aptamers. Our findings may have translatable relevance in the application of aptamer anticoagulants for clinical conditions in which blood is in direct contact with non-biological surfaces such as those encountered in cardiopulmonary bypass circuits. PMID:23054460

Krishnan, Anandi; Vogler, Erwin A; Sullenger, Bruce A; Becker, Richard C

2013-01-01

234

Comparison of 2D Hybrid Simulational and Experimental Results for Dual-Frequency Capacitively Coupled Argon Plasmas  

NASA Astrophysics Data System (ADS)

A two-dimensional hybrid simulation scheme is proposed to study the characteristics of dual-frequency (DF) capacitively coupled plasma (CCP) discharge based on the geometry of real device. Given the experimental parameters for argon plasma, the output from the fluid module such as ion density, number flux, electron temperature and the Monte-Carlo collision (MCC) results of ion energy distribution function (IEDF) as well as electron energy distribution function (EEDF) are obtained and discussed in detail. A novel complete floating double probe is designed to measure both density and temperature of electron and a quadrupole mass spectrometer is also equipped for IEDF investigations. The measurements on the density of bulk plasma, electron temperature and IEDF agree well, qualitatively, with the simulated results. A comparison with experimental results indicates that, since the structure of real device is taken into account, this model is capable of describing the global dynamic characteristics occurred in DF-CCP and presenting more reliable results than the model with an ideal chamber structure.

Bi, Zhenhua; Xu, Xiang; Liu, Yongxin; Jiang, Xiangzhan; Lu, Wenqi; Wang, Younian

2011-04-01

235

Effects of matching network on the hysteresis during E and H mode transitions in argon inductively coupled plasma  

SciTech Connect

An experimental investigation of the hysteresis during the E (capacitive coupling) and H mode (inductive coupling) transitions at various matching situation in argon inductively coupled plasma is reported. At high pressure, the results show two hysteresis loops involved the plasma density, applied power, and forward power, as well as the electrical parameters in the discharge circuit, when the series capacitance is cycled. The measured electron density versus applied power shows that the hysteresis loop shrinks with the decrease of the matching capacitance, and the same trend is discovered on the input current, voltage, and phase angle. In addition, for the case of small capacitance, the current (or voltage) jumps to a low value when the discharge passes through the E to H mode transition regime. Contrarily, for the case of large capacitance, the current jumps to a high value while the voltage is almost constant. The evolution characteristics of the plasma and circuit parameters observed imply that the nonlinear behavior of the matching situation may be one of the determined factors for hysteresis.

Gao Fei; Zhao Shuxia; Li Xiaosong; Wang Younian [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2010-10-15

236

Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering  

NASA Astrophysics Data System (ADS)

Gas-temperature and velocity profiles at the exit plane of a thermal argon plasma torch have been determined directly from a high-resolution Doppler-shifted line-shape analysis of laser light scattered by the plasma. Peak temperature and velocity values observed were 13 350 K+/-7% and 1100 m s-1+/-3%. Velocities as low as 45 m s-1+/-45% were measured in the fringe of the jet. An injection-seeded pulsed neodymium-doped yttrium aluminum garnet laser was used as the laser source and the scattered laser light was analyzed with a scanning tandem Fabry-Pérot interferometer. Temperature data obtained from laser scattering are compared with values obtained from emission spectroscopy and show a severe departure from local thermodynamic equilibrium (LTE) in the outer regions of the jet. Gas temperatures were observed to increase as the torch operating current increased from 300 to 500 A, but remained constant as the operating current increased to 900 A. However, electron temperatures and densities continued to increase with operating current. This suggests that increasing the electrical power drives the plasma away from LTE. Measured temperature and velocity profiles were found to be nearly parabolic.

Snyder, S. C.; Reynolds, L. D.; Lassahn, G. D.; Fincke, J. R.; Shaw, C. B., Jr.; Kearney, R. J.

1993-03-01

237

Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering  

SciTech Connect

Gas-temperature and velocity profiles at the exit plane of a thermal argon plasma torch have been determined directly from a high-resolution Doppler-shifted line-shape analysis of laser light scattered by the plasma. Peak temperature and velocity values observed were 13 350 K[plus minus]7% and 1100 m s[sup [minus]1][plus minus]3%. Velocities as low as 45 m s[sup [minus]1][plus minus]45% were measured in the fringe of the jet. An injection-seeded pulsed neodymium-doped yttrium aluminum garnet laser was used as the laser source and the scattered laser light was analyzed with a scanning tandem Fabry-Perot interferometer. Temperature data obtained from laser scattering are compared with values obtained from emission spectroscopy and show a severe departure from local thermodynamic equilibrium (LTE) in the outer regions of the jet. Gas temperatures were observed to increase as the torch operating current increased from 300 to 500 A, but remained constant as the operating current increased to 900 A. However, electron temperatures and densities continued to increase with operating current. This suggests that increasing the electrical power drives the plasma away from LTE. Measured temperature and velocity profiles were found to be nearly parabolic.

Snyder, S.C.; Reynolds, L.D.; Lassahn, G.D.; Fincke, J.R.; Shaw, C.B. Jr. (Idaho National Engineering Laboratory, EG G Idaho, Inc., P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)); Kearney, R.J. (Department of Physics, University of Idaho, Moscow, Idaho 83843 (United States))

1993-03-01

238

Acetylene-argon plasmas measured at an rf-biased substrate electrode for diamond-like carbon deposition: II. Ion energy distributions  

Microsoft Academic Search

Ion energy distributions (IEDs) have been determined at the radio frequency (rf)-biased electrode in an inductively coupled acetylene-argon plasma for various substrate bias voltages and frequencies under conditions suitable for diamond-like carbon (DLC) and polymer-like film deposition. These are compared with those obtained at a capacitively coupled plasma grounded wall. In the former, for pressures <25 mTorr, the IEDs exhibit

A. Baby; C. M. O. Mahony; P. Lemoine; P. D. Maguire

2011-01-01

239

[The treatment of herpetic keratitis by ion-plasma coagulation of the cornea].  

PubMed

The authors propose a new treatment method for herpetic keratitis: ion-plasmic corneal coagulation using a "Strimer" device designed and build by themselves. After successfully experimenting the action of the ion-plasmic flow on the guinea pigs cornea, the "Strimer" device has been used in the clinic. Using this device, 32 patients with herpetic keratitis have been treated, 3 of them having metaherpetical keratitis. Most of the patients (25) were cured and left the hospital after 4-7 days from intervention, with the visual acuity improved from 0.1-0.5 to 0.7-1. The others 7 patients left the hospital after 10-15 days from the intervention, with a better visual acuity. PMID:8338829

Slipenicaia, V D; Lupan, D S; Rudenco, V M

240

Osseointegration assessment of chairside argon-based nonthermal plasma-treated Ca-P coated dental implants.  

PubMed

This study investigated the effect of an Argon-based nonthermal plasma (NTP) surface treatment-operated chairside at atmospheric pressure conditions applied immediately prior to dental implant placement in a canine model. Surfaces investigated comprised: Calcium-Phosphate (CaP) and CaP + NTP (CaP-Plasma). Surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and chemistry by X-ray photoelectron spectroscopy (XPS). Six adult beagles dogs received 2 plateau-root form implants (n = 1 each surface) in each radii, providing implants that remained 1 and 3 weeks in vivo. Histometric parameters assessed were bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Statistical analysis was performed by Kruskall-Wallis (95% level of significance) and Dunn's post-hoc test. The XPS analysis showed peaks of Ca, C, O, and P for the CaP and CaP-Plasma surfaces. Both surfaces presented carbon primarily as hydrocarbon (C-C, C-H) with lower levels of oxidized carbon forms. The CaP surface presented atomic percent values of 38, 42, 11, and 7 for C, O, Ca, and P, respectively, and the CaP-Plasma presented increases in O, Ca, and P atomic percent levels at 53, 12, and 13, respectively, in addition to a decrease in C content at 18 atomic percent. At 1 week no difference was found in histometric parameters between groups. At 3 weeks significantly higher BIC and BAFO were observed for CaP-Plasma treated surfaces. Surface elemental chemistry was modified by the Ar-based NTP. Ar-based NTP improved bone formation around plateau-root form implants at 3 weeks compared with CaP treatment alone. PMID:22826209

Giro, Gabriela; Tovar, Nick; Witek, Lukasz; Marin, Charles; Silva, Nelson R F; Bonfante, Estevam A; Coelho, Paulo G

2012-07-24

241

Enhancement of injection and acceleration of electrons in a laser wakefield accelerator by using an argon-doped hydrogen gas jet and optically preformed plasma waveguide  

SciTech Connect

A systematic experimental study on injection of electrons in a gas-jet-based laser wakefield accelerator via ionization of dopant was conducted. The pump-pulse threshold energy for producing a quasi-monoenergetic electron beam was significantly reduced by doping the hydrogen gas jet with argon atoms, resulting in a much better spatial contrast of the electron beam. Furthermore, laser wakefield electron acceleration in an optically preformed plasma waveguide based on the axicon-ignitor-heater scheme was achieved. It was found that doping with argon atoms can also lower the pump-pulse threshold energy in this experimental configuration.

Ho, Y.-C.; Hung, T.-S.; Chen, S.-Y.; Chou, M.-C. [Department of Physics, National Central University, Jhong-Li 320, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Yen, C.-P.; Wang, J. [Department of Physics, National Central University, Jhong-Li 320, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Chu, H.-H. [Department of Physics, National Central University, Jhong-Li 320, Taiwan (China); Lin, J.-Y. [Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China)

2011-06-15

242

One- and two-dimensional modeling of argon K-shell emission from gas-puff Z-pinch plasmas  

NASA Astrophysics Data System (ADS)

In this paper, a theoretical model is described and demonstrated that serves as a useful tool for understanding K-shell radiating Z-pinch plasma behavior. Such understanding requires a self-consistent solution to the complete nonlocal thermodynamic equilibrium kinetics and radiation transport in order to realistically model opacity effects and the high-temperature state of the plasma. For this purpose, we have incorporated into the MACH2 two-dimensional magnetohydrodynamic (MHD) code [R. E. Peterkin et al., J. Comput. Phys. 140, 148 (1998)] an equation of state, called the tabular collisional radiative equilibrium (TCRE) model [J. W. Thornhill et al., Phys. Plasmas 8, 3480 (2001)], that provides reasonable approximations to the plasma's opacity state. MACH2 with TCRE is applied toward analyzing the multidimensional implosion behavior that occurred in Decade Quad (DQ) [D. Price et al., Proceedings of the 12th IEEE Pulsed Power Conference, Monterey, CA, edited by C. Stallings and H. Kirbie (IEEE, New York, 1999), p. 489] argon gas puff experiments that employed a 12 cm diameter nozzle with and without a central gas jet on axis. Typical peak drive currents and implosion times in these experiments were ~6 MA and ~230 ns. By using Planar Laser Induced Fluorescence measured initial density profiles as input to the calculations, the effect these profiles have on the ability of the pinch to efficiently produce K-shell emission can be analyzed with this combined radiation-MHD model. The calculated results are in agreement with the experimental result that the DQ central-jet configuration is superior to the no-central-jet experiment in terms of producing more K-shell emission. These theoretical results support the contention that the improved operation of the central-jet nozzle is due to the better suppression of instabilities and the higher-density K-shell radiating conditions that the central-jet configuration promotes. When we applied the model toward projecting argon K-shell yield behavior for Sandia National Laboratories' ZR machine (~25 MA peak drive currents, ~100 ns implosion times) [D. McDaniel et al., Proceedings of the 5th International Conference on Dense Z-Pinches, Albuquerque, NM, 2002, edited by J. Davis, C. Deeney, and N. R. Pereira (American Institute of Physics, New York, 2002), Vol. 651, p. 23] for experiments that utilize the 12 cm diameter central-jet nozzle configuration, it predicts over 1 MJ of K-shell emission is attainable.

Thornhill, J. W.; Chong, Y. K.; Apruzese, J. P.; Davis, J.; Clark, R. W.; Giuliani, J. L.; Terry, R. E.; Velikovich, A. L.; Commisso, R. J.; Whitney, K. G.; Frese, M. H.; Frese, S. D.; Levine, J. S.; Qi, N.; Sze, H.; Failor, B. H.; Banister, J. W.; Coleman, P. L.; Coverdale, C. A.; Jones, B.; Deeney, C.

2007-06-01

243

Electron properties and air mixing in radio frequency driven argon plasma jets at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A time modulated radio frequency (RF) plasma jet operated with an Ar mixture is investigated by measuring the electron density and electron temperature using Thomson scattering. The measurements have been performed spatially resolved for two different electrode configurations and as a function of the plasma dissipated power and air concentration admixed to the Ar. Time resolved measurements of electron densities and temperatures during the RF cycle and after plasma power switch-off are presented. Furthermore, the influence of the plasma on the air entrainment into the effluent is studied using Raman scattering.

van Gessel, Bram; Brandenburg, Ronny; Bruggeman, Peter

2013-08-01

244

Arc Root Motion in an Argon-Hydrogen DC Plasma Torch  

Microsoft Academic Search

Arc root motion on the anode surface of a DC nontransferred plasma torch was observed. Adding hydrogen changes the arc root attachment from a diffused type to a constricted type, and the arc root of Ar-H2 plasma suddenly jumps from one spot to another irregularly. Images of the arc root motions taken by a high-speed video camera are presented.

Heji Huang; Wenxia Pan; Chengkang Wu

2008-01-01

245

Thermal Characteristics of a High and Low Mass Flux Argon Plasma Jet.  

National Technical Information Service (NTIS)

The thermal characteristics are determined by the plasma jets emanating from the F40 plasma torch which is manufactured by Thermal Dynamics Corp. A grating spectrometer was used to determine the temperature fields of high and low mass flux jets generated ...

C. J. Cremers E. Pfender

1964-01-01

246

Effects of coagulation factor XIII on intestinal functional capillary density, leukocyte adherence and mesenteric plasma extravasation in experimental endotoxemia  

PubMed Central

Introduction The objective of this study was to determine the effects of the administration of the coagulation factor XIII (F XIII) on intestinal functional capillary density, leukocyte adherence and mesenteric plasma extravasation during experimental endotoxemia. Methods In a prospective, randomized, controlled animal study 42 male Wistar rats were divided into three groups. Group 1 served as the control group. Groups 2 (lipopolysaccharide (LPS) group) and 3 (F XIII group) received endotoxin infusions (2.5 mg/kg/h for 2 hours). In group 3, 50 U/kg body weight F XIII was continuously administered during the first 30 minutes of endotoxemia. F XIII levels were measured in all animals. One half of the animals of each group were studied for intestinal functional capillary density (FCD) and leukocyte adherence on venular endothelium by intravital fluorescence microscopy (IVM). In the other half of each group, mesenteric plasma extravasation (FITC-albumin) was determined by IVM. Results The F XIII level was significantly increased in the F XIII treatment group. In the LPS group, endotoxemia led to a significant reduction of mucosal FCD (-18.5%; p < 0.01 versus control group). F XIII administration in the F XIII group attenuated the decrease in mucosal FCD (-3.7% compared to control; p < 0.05 versus LPS group). During endotoxemia, a significant increase of leukocyte adherence at the endothelium could be noted in the LPS group compared to the control group. Leukocyte adherence at the endothelium and plasma extravasation in the F XIII group did not differ significantly from the LPS group. Conclusion Factor XIII protected mucosal capillary perfusion against endotoxin-induced impairment in an experimental sepsis model in rats, whereas leukocyte adherence and plasma extravasation remained unchanged.

Birnbaum, Jurgen; Hein, Ortrud Vargas; Luhrs, Carsten; Ruckbeil, Oskar; Spies, Claudia; Ziemer, Sabine; Grundling, Matthias; Usichenko, Taras; Meissner, Konrad; Pavlovic, Dragan; Kox, Wolfgang J; Lehmann, Christian

2006-01-01

247

Tissue effects of argon gas flow during electrosurgery  

NASA Astrophysics Data System (ADS)

Argon gas-enhanced electrosurgery has recently been introduced for its potential beneficial effects on hemostasis during electrical cutting. In this study, the influence of argon gas on electrosurgery on tissue was investigated. A standard electrosurgery unit was used extended with a gas unit and accommodated handset, which enabled a flow of argon blown along the electrode in contact with tissue. The temperature distribution was visualized in polyacrylamide gel using a color-Schlieren technique. Bovine tissue was used to evaluate the macroscopic effect of the lesions. The electrode was moved over the tissue surface with different settings for speed, gas flow, gas-outlet positioning and depth of the electrode in the tissue. During cutting, coagulation was significantly increased using argon gas; coagulation on both sides of the track ranging from 1.0 mm without argon flow up to 4.5 mm with argon flow could be obtained. Changing the gas flow from laminar to affected neither the coagulation nor the cutting. The extent of the coagulation depended on the combination of power and distance of the gas-outlet to the tissue. The coagulation depth beyond the bottom of the tracks was not influenced by argon and remained less than 1 mm. Argon gas-enhanced electrode surgery is especially effective when just touching the tissue thus obtaining a superficial coagulation (and hemostasis) of the surrounding tissue.

van Swol, Christiaan F.; van Vliet, Remco J.; Grimbergen, Matthijs G.; Verdaasdonk, Rudolf M.

1998-04-01

248

Effects of the shielding cylinder and substrate on the characteristics of an argon radio-frequency atmospheric glow discharge plasma jet  

SciTech Connect

With unique features of low breakdown voltages, large and uniform discharge areas and high concentrations of chemically reactive species, radio-frequency, atmospheric-pressure glow discharge (rf APGD) plasma sources produced with bare-metallic electrodes have shown promising prospects in the field of materials processing. In this paper, the spatial distributions (i.e., the directly measured integrated axial distribution and the radial distribution by using the inverse Abel transform) of the emission intensities of the Ar I 696.5 nm line are studied for the argon rf APGD plasma jet under different operation conditions, including variations of the rf power input or the argon flow rate, the existence of the solid shielding cylinder or the substrate. The experimental results show that, with other parameters being unchanged, the emission intensities of the Ar I 696.5 nm line increase with increasing the rf power input or the argon flow rate; and the solid shielding cylinder has more significant influences on the characteristics of the plasma impinging jet by reducing the mass flow rate of the ambient air entrained into the plasma jet region than those for the cases without the existence of the substrate at the downstream of the plasma torch nozzle exit.

Li Guo; Le Peisi; Li Heping; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2010-05-15

249

Effects of the shielding cylinder and substrate on the characteristics of an argon radio-frequency atmospheric glow discharge plasma jet  

NASA Astrophysics Data System (ADS)

With unique features of low breakdown voltages, large and uniform discharge areas and high concentrations of chemically reactive species, radio-frequency, atmospheric-pressure glow discharge (rf APGD) plasma sources produced with bare-metallic electrodes have shown promising prospects in the field of materials processing. In this paper, the spatial distributions (i.e., the directly measured integrated axial distribution and the radial distribution by using the inverse Abel transform) of the emission intensities of the Ar I 696.5 nm line are studied for the argon rf APGD plasma jet under different operation conditions, including variations of the rf power input or the argon flow rate, the existence of the solid shielding cylinder or the substrate. The experimental results show that, with other parameters being unchanged, the emission intensities of the Ar I 696.5 nm line increase with increasing the rf power input or the argon flow rate; and the solid shielding cylinder has more significant influences on the characteristics of the plasma impinging jet by reducing the mass flow rate of the ambient air entrained into the plasma jet region than those for the cases without the existence of the substrate at the downstream of the plasma torch nozzle exit.

Li, Guo; Le, Pei-Si; Li, He-Ping; Bao, Cheng-Yu

2010-05-01

250

Synthesis of ultrafine ceramic and metallic powders in a thermal argon rf plasma  

SciTech Connect

Ultrafine powders of SiC, Si/sub 3/N/sub 4/, Ni, and Al/sub 2/O/sub 3/ have been prepared in a rf-plasma reactor, utilizing an induction plasma tube designed at Los Alamos. The primary particle size of the ceramic powders ranges from 5 to 50 nm. Silicon carbide and alumina are ultrapure crystalline powders, while silicon nitride is amorphous for surface areas greater than 100 m/sup 2//g. Plasma nickel powder will sinter to full density at 1073 K.

Vogt, G.J.; Vigil, R.S.; Newkirk, L.R.; Trkula, M.

1985-01-01

251

Experimental Characterization of Dual-Frequency Capacitively Coupled Plasma with Inductive Enhancement in Argon  

NASA Astrophysics Data System (ADS)

The dual-frequency capacitively coupled plasma (DF-CCP) with inductive enhancement system is a newly designed plasma reactor. Different from the conventional inductively coupled plasma (ICP) reactors, now a radio frequency (rf) power is connected to an antenna placed outside the chamber with a one-turn bare coil placed between two electrodes in DF-CCP. This paper gives a detailed description of its structure. Moreover, investigations on some characteristics of discharges in this apparatus were made via a Langmuir probe.

Bai, Yang; Jin, Chenggang; Yu, Tao; Wu, Xuemei; Zhuge, Lanjian; Ning, Zhaoyuan; Ye, Chao; Ge, Shuibing

2013-10-01

252

Some Considerations on the Microwave Electrodeless Discharge. Plasma Diagnostics in Argon, Helium or Nitrogen Atmospheres.  

National Technical Information Service (NTIS)

Microwave electrodeless discharges in enclosed quartz containers (electrodeless discharge lamps, EDL) are often utilized in optical spectroscopy as line sources for absorption and/or fluorescence measurements of atoms in flames and high temperature plasma...

R. Avni J. D. Winefordner

1974-01-01

253

Comparison of glow argon plasma-induced surface changes of thermoplastic polymers  

NASA Astrophysics Data System (ADS)

Modification of high-density polyethylene (PE), polytetrafluoroethylene (PTFE), polystyrene (PS), polyethyleneterephthalate (PET) and polypropylene (PP) by Ar plasma was studied. The amount of the ablated material was determined by gravimetry. Wettability of polymers after the plasma treatment was determined from the contact angle measurement. The changes in the surface morphology of polymers were observed using atomic force microscopy (AFM). Chemical structure of modified polymers was characterized by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Surface changes were also studied by the determination of electrokinetic potential (?-potential). It was found that under the plasma treatment the polymers are ablated and their surface morphology and roughness are changed dramatically. XPS measurements indicate an oxidation of the polymer surface. The plasma treatment results in a dramatic increase of the ?-potential. EPR data show different radical amount present on the treated surface of all polymers. Most significant changes due to the degradation of polymer chains are observed on PTFE.

?ezní?ková, A.; Kolská, Z.; Hnatowicz, V.; Stopka, P.; Švor?ík, V.

2011-01-01

254

Argon\\/UF6 plasma experiments: UF6 regeneration and product analysis  

Microsoft Academic Search

An experimental and analytical investigation was conducted to aid in developing some of the technology necessary for designing a self-critical fissioning uranium plasma core reactors (PCR). This technology is applicable to gaseous uranium hexafluoride nuclear-pumped laser systems. The principal equipment used included 1.2 MW RF induction heater, a d.c. plasma torch, a uranium tetrafluoride feeder system, and batch-type fluorine\\/UF6 regeneration

W. C. Roman

1980-01-01

255

Influence of the excited states on the electron-energy distribution function in low-pressure microwave argon plasmas  

Microsoft Academic Search

In this work the influence of the excited states on the electron-energy distribution function has been determined for an argon microwave discharge at low pressure. A collisional-radiative model of argon has been developed taking into account the most recent experimental and theoretical values of argon-electron-impact excitation cross sections. The model has been solved along with the electron Boltzmann equation in

A. Yanguas-Gil; J. Cotrino; A. R. González-Elipe

2005-01-01

256

The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications  

NASA Astrophysics Data System (ADS)

Tungsten-based coatings have potential application in the plasma-facing components in future nuclear fusion reactors. By the combination of refractory tungsten with highly thermal conducting copper, or steel as a construction material, functionally graded coatings can be easily obtained by plasma spraying, and may result in the development of a material with favorable properties. During plasma spraying of these materials in the open atmosphere, oxidation is an important issue, which could have adverse effects on their properties. Among the means to control it is the application of inert gas shrouding, which forms the subject of this study and represents a lower-cost alternative to vacuum or low-pressure plasma spraying, potentially applicable also for spraying of large surfaces or spacious components. It is a continuation of recent studies focused on the effects of various parameters of the hybrid water-argon torch on the in-flight behavior of copper and tungsten powders and the resultant coatings. In the current study, argon shrouding with various configurations of the shroud was applied. The effects of torch parameters, such as power and argon flow rate, and powder morphology were also investigated. Their influence on the particle in-flight behavior as well as the structure, composition and properties of the coatings were quantified. With the help of auxiliary calculations, the mass changes of the powder particles, associated with oxidation and evaporation, were assessed.

Mat?jí?ek, J.; Kavka, T.; Bertolissi, G.; Ctibor, P.; Vilémová, M.; Mušálek, R.; Nevrlá, B.

2013-06-01

257

Argon/Hexamethyldisiloxane Plasma Effects on Poly Propylene Film Surface Properties  

NASA Astrophysics Data System (ADS)

In this work a DC plasma reactor was used for deposition of plasma polymerized coating from hexamethyldisiloxane-Ar (35/65%) mixture on polypropylene films. Surface energy parameter have been calculated using Owens-Wendt approaches with the sessile drop method are used to obtain the dispersive ?D and polar ?P component of surface free energy. The surface morphology of samples were investigated using scanning electron microscope. Also the chemical properties and wetability of prepared samples were tested using Fourier transform infrared spectroscopy and contact angle measurement, respectively.

Mortazavi, S. H.; Ghoranneviss, M.; Sari, A. H.

2010-10-01

258

Absorption spectroscopy measurements of argon metastable and resonant atom density in atmospheric pressure Ar-He surface-wave plasmas using a low pressure lamp  

SciTech Connect

The densities of metastable and resonant atom were measured in atmospheric pressure Ar-He surface-wave plasmas. Measurements were performed using an absorption spectroscopy method taking into account the Voigt profiles of the plasma lines. The density values of the argon {sup 3}P{sub 2}, {sup 3}P{sub 0} (metastable atoms) and {sup 3}P{sub 1} (resonant atoms) levels measured in pure argon discharges are in good agreement with those reported in the literature. A drastic decrease of metastable and resonant densities is observed when introducing helium in amounts as low as 2%. The influence of electron density and gas temperature on the population mechanisms (direct electron excitation from the ground state and dissociative recombination) of metastable and resonant atoms is discussed using a simplified theoretical model.

Munoz, J.; Margot, J. [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-ville, Montreal, Quebec H3C 3J7 (Canada); Calzada, M. D. [Grupo de Espectroscopia de Plasmas, Edificio A. Einstein, Campus de Rabanales, Universidad de Cordoba, E-14071 Cordoba (Spain)

2012-01-15

259

Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing  

SciTech Connect

An experiment of He gas-contact for generating population inversion in a recombining Ar plasma jet is carried out. Population inversion between Ar I excited states 5s' {yields} 4p'[1/2]1 and 5s' {yields} 4p[3/2]1,2, [5/2]2,3 is created by helium gas-contact cooling of electrons, whereas it is not created without gas-contact. Ar I lines 1.14 {mu}m, 1.34 {mu}m, and 1.09 {mu}m are strongly enhanced due to the He gas cooling. It is experimentally found that helium gas contact effectively lowers electron temperature of the Ar plasma jet. The mechanisms giving rise to population inversion are discussed in terms of atomic collisional processes of the recombining plasma. The experimental results of electron temperature and population densities are discussed by simple numerical analysis which we previously developed. It is shown that the experimental results are well explained by our modeling quantitatively for the case without gas contact, except that the agreement of number densities of lower lying non-LTE levels is qualitative for the case with the gas contact.

Akatsuka, H.; Kano, K. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10, O-Okayama, Meguro-ku, Tokyo, 152-8550 (Japan)

2005-05-16

260

Effect of CO on NO and N{sub 2}O conversions in nonthermal argon plasma  

SciTech Connect

200-600 ppm of CO inhibit NO conversion in nonthermal Ar plasma, but do not produce N{sub 2}O. However, 1.01% of CO has no effect on NO conversion, but produces N{sub 2}O. In general, N{sub 2}O conversion in Ar plasma decreases with increasing CO concentration. These experimental results cannot be explained by charge transfer reactions of Ar{sup +}. Selectivity analysis of all excited states of Ar possibly contributing to NO{sub x} conversion without and with CO suggests that only Ar({sup 3}P{sub 2}) contributes to NO{sub x} conversion and CO dissociation. A kinetic model of 43 reactions is required to model NO conversion or N{sub 2}O conversion in Ar without CO, whereas 81 reactions are required to model NO conversion and N{sub 2}O conversion in Ar with CO. At constant gas pressure, a single set of model parameters can predict NO conversion or N{sub 2}O conversion without and with CO. All experimental results can be explained using a reaction mechanism in which excited neutral states of Ar are the only active species, which supports the conclusion that cations have a negligible impact on these nonthermal plasma reactions.

Zhao Guibing; Argyle, Morris D.; Radosz, Maciej [Department of Chemical and Petroleum Engineering, College of Engineering, University of Wyoming, Laramie, Wyoming 82071-3295 (United States)

2006-06-01

261

Modelling of the heat transfer and fluid flow in a radio-frequency plasma torch with argon-hydrogen as the working gas  

Microsoft Academic Search

Modelling results concerning the heat transfer and fluid flow in a radio-frequency plasma torch with argon and hydrogen as the working gas are presented. The diffusion of hydrogen in the gas mixture due to the presence of temperature and concentration gradients within the torch has been modelled by using the combined-diffusion-coefficient approach. Included in the modelling are also the effects

Xi Chen; M. Sugasawa; N. Kikukawa

1998-01-01

262

TOPICAL REVIEW: Optical emission spectroscopy in low-temperature plasmas containing argon and nitrogen: determination of the electron temperature and density by the line-ratio method  

NASA Astrophysics Data System (ADS)

This article reviews a variety of methods to obtain the electron temperature and density by the emission line ratios for low-temperature plasmas containing argon or nitrogen gas. Based on the collisional-radiative model of excited particles, the underlying principle of each of these methods is described, along with the criterion on how to select an appropriate line-ratio method according to the discharge conditions. Limitations on the application of each line-ratio technique are also discussed.

Zhu, Xi-Ming; Pu, Yi-Kang

2010-10-01

263

Effects of argon laser on in vitro aggregation of platelets in platelet rich plasma and whole blood  

SciTech Connect

The effects of an Argon laser on platelet aggregation were studied, since platelets may be exposed to laser energy when used intravascularly. Various preparations of platelets in platelet rich plasma (PRP) and whole blood, with or without aspirin, were tested with the aggregating agents ADP, collagen, thrombin, and epinephrine. Simultaneous release of ATP was also measured in PRP. At relatively low levels of irradiation, platelet aggregation was potentiated. Enhancement was evidenced by an increase in percent aggregation, earlier onset of the reaction, and reduction in the amount of aggregating agent required. In PRP, the mechanism of laser potentiation appeared to be the release of endogenous ATP from platelets. At relatively high levels of irradiation, platelets were destroyed and aggregation abolished. In whole blood, the mechanism was somewhat more complicated since release of ATP occurred from RBCs as well as platelets. Spontaneous aggregation following laser treatment occurred in isolated instances in PRP and in every trial in whole blood preparations. Aspirin ingestion inhibited the laser's effects in PRP but not in whole blood. These results may have important clinical implications for laser angioplasty, and the potentiated aggregation response may prove useful in laboratory studies of platelet function.

Doerger, P.T.; Glueck, H.I.; McGill, M.

1988-06-01

264

Splash plasma channels produced by picosecond laser pulses in argon gas for laser wakefield acceleration  

NASA Astrophysics Data System (ADS)

Short-lived, ˜10ps, deep plasma channels, with their lengths of ˜1mm and diameters of ˜20?m, are observed and characterized in Ar gas jets irradiated by moderate intensity, ˜1015-16W/cm2, laser pulses with a duration from subpicosecond to several picoseconds. The channels, upon 2D particle-in-cell simulations including ionization, fit well in the guiding of high intensity femtosecond laser pulses and, therefore, in laser wakefield acceleration with a controllable electron self-injection.

Mizuta, Y.; Hosokai, T.; Masuda, S.; Zhidkov, A.; Makito, K.; Nakanii, N.; Kajino, S.; Nishida, A.; Kando, M.; Mori, M.; Kotaki, H.; Hayashi, Y.; Bulanov, S. V.; Kodama, R.

2012-12-01

265

Comparative study on the atmospheric pressure plasma jets of helium and argon  

NASA Astrophysics Data System (ADS)

Formation mechanisms for atmospheric pressure plasma jets (APPJ) of He and Ar are investigated by comparing the discharge current, light emission from jet, and time-resolved image of the discharge. A longer jet of He (Ar) is available with active (ground) electrode sitting at downstream side. The jet of He outside active electrode arises from corona discharge, while that of Ar outside ground electrode results from charge overflow, and can be diffusive or filamentous in different phases of the applied voltage. The underlying mechanisms are discussed. These results can be helpful for the further mechanism investigation and implementation of APPJs.

Shao, Xian-Jun; Jiang, Nan; Zhang, Guan-Jun; Cao, Ze-xian

2012-12-01

266

Deposition of amorphous hydrogenated silicon carbide films using organosilanes in an argon/hydrogen plasma  

SciTech Connect

Nearly stoichiometric, amorphous silicon carbide films with a relatively low hydrogen content were deposited from organsilanes on a variety of substrates in a microwave-generated plasma without external heating. The films undergo little weight loss upon pyrolysis to 800 [degree]C. The effect of the different deposition parameters on the film composition and the exhaust gas was established through a battery of tests including infrared Fourier transform spectroscopy, Auger electron spectroscopy, x-ray photoelectron spectroscopy, ellipsometry, and mass spectroscopy. For a given power level there is a limiting feeding rate of the precursor under which operation of the system is dominated by thermodynamics and thus leads to the desired product. Beyond that limit, excessive hydrogen incorporation and carbosilane polymer formation takes place. The hydrogen content of the plasma is also an important parameter affecting the chemistry of the deposition. In the thermodynamically dominated regime the nature of the precursor has no effect on the quality of the film. It affects only the relative utilization efficiency.

Maya, L. (Chemistry Division, Oak Ridge National Laboratory, P.O. Box 2008-6119, Oak Ridge, Tennessee 37831 (United States))

1994-05-01

267

Ion and neutral argon temperatures in electron cyclotron resonance plasmas by Doppler broadened emission spectroscopy  

SciTech Connect

Neutral and ionic gas temperatures ({ital T}{sub {ital n}} and {ital T}{sub {ital i}}) are crucial parameters in the plasma processing of materials (etching and film deposition). Here we evaluate a method used for obtaining the temperatures, i.e., the Doppler broadening, of emission lines. We focus on Ar lines from microwave electron cyclotron resonance plasmas. We use the same technique for {ital both} ions and neutrals. Three factors are important in achieving accuracy: (1) knowing the correct instrument width at the central wavelength of {ital each} ion and neutral line, (2) understanding the noise-dependent variation in the measured widths, and (3) knowing how the magnetic field affects the spectra. We find that {ital T} can be determined to within {similar_to}100 {degree}C. {ital T}{sub {ital i}} and {ital T}{sub {ital n}} are typically found to be {similar_to}0.5 and {lt}0.1 eV, respectively for 0.5 mTorr Ar. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Tsu, D.V.; Young, R.T.; Ovshinsky, S.R. [Energy Conversion Devices, Troy, Michigan 48084 (United States); Klepper, C.C.; Berry, L.A. [Oak Ridge National Laboratory, Oak Ridge, Tennesse 37831 (United States)

1995-05-01

268

The role of radiation in modelling of argon inductively coupled plasmas at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Modelling of inductively coupled plasmas at atmospheric pressure has been developed for years, integrating fluid dynamics, electromagnetism and heat transfer. In this work, special attention has been devoted to radiation transfer. Two radiation models have been implemented: the net emission coefficient and the P1 model. These models have been run with different torch geometries and input powers. The parametric study shows that they are very sensitive to parameters such as the thermal and electrical conductivity of the gas and input power. The temperature distributions have been compared with the measurements available in the literature. The spectral P1 model is more accurate at the expense of the computing time. The radiative heat losses are below 5% in small torches such as those used in spectrochemical analysis, but can exceed 40% in large torches (40 mm diameter or more), becoming the main cooling mechanism.

Lacombe, J. G.; Delannoy, Y.; Trassy, C.

2008-08-01

269

Continuous flow vapor generation for inductively coupled argon plasma spectrometric analysis. Part 2. Arsenic.  

PubMed

Total arsenic is determined by inductively coupled plasma atomic emission using hydride vapor generation. A 1 g sample is wet washed in a 16 x 150 mm 10 mL volumetric test tube on a programmed heating block with nitric, sulfuric, and perchloric acids at up to 310 degrees C. After treatment with hydrochloric acid and potassium iodide, arsenic is reduced by sodium borohydride to arsine in a simplified continuous flow manifold. A standard pneumatic nebulizer affects the gas-liquid separation of AsH3, which is quantified by ICP atomic emission at 193.756 nm. The instrument detection limit for the method has been determined to be 0.4 microgram/L. For a 10:1 dilution of a nominal 1 g sample, the detection limit is 4 micrograms/kg and the linear range is up to 4 mg/kg. Recoveries from 3 matrixes were 99-104%, with a typical RSD of 2%. The method has demonstrated statistical control for samples of biological interest and is especially well suited to analysis of small samples. PMID:1874698

Tracy, M L; Littlefield, E S; Moller, G

270

Coagulopathies in Naja naja karachiensis (black Pakistan cobra) bites and its effect on coagulation tests upon storage of platelet-poor plasma.  

PubMed

The aim of this study was to evaluate the effect of venom from Naja naja karachiensis on platelet-poor plasma, activated partial thromboplastin time (aPTT), prothrombin time (PT) / international normalized ratio (INR), thrombin time (TT) and to evaluate its effect on clotting time upon storage of plasma for a specific time period with possible mechanism responsible for that. Prolongation of PT / INR, aPTT and TT was observed when different concentrations of venom were introduced due to degeneration of fibrinogen. Preservation of plasma for three months further prolong clotting time for coagulation tests, however, difference of PT and TT results were not very prominent as compared to aPTT. Minute concentrations of cobra venom and short as well as long storage of platelet-poor plasma badly affects the INR ratio. PMID:23285662

Asad, Muhammad Hassham Hassan Bin; Razi, Muhammad Tahir; Khan, Taous; Najam-Us-saqib, Qazi; Murtaza, Ghulam; Hussain, Muhammad Shahzad; Hussain, Muhammad Sikandar; Karim, Sabiha; Hussain, Izhar

271

Measurement of ^39Ar/Ar ratios using AMS on underground argon samples using the newly developed ultra-pure Al lined plasma chamber  

NASA Astrophysics Data System (ADS)

The first application of ^39Ar AMS at the ATLAS linac of Argonne National Laboratory (ANL) to date ocean water samples relevant to oceanographic studies was most successful and has been reported on. In particular the use of a quartz liner in the plasma chamber of the Electron Cyclotron Resonance (ECR) ion source enabled a potassium reduction of a factor ˜100 compared to previous runs without liners and allowed measurements down to ^39Ar/Ar = 4.2x10-17. We are currently working on improving the AMS method for ^39Ar by following two ion source development paths to allow for higher Ar beam currents coupled to lower ^39K background rates. Both methods are combined with new cleaning techniques developed for removing both particulates and other materials from surfaces, largely driven by the semiconductor industry. The driving force for the use of AMS to measure ^39Ar is to search for a source of argon that has a low concentration of ^39Ar. Such a source of argon would be useful for new liquid argon detectors that are being developed for detecting dark matter WIMPs (Weakly Interacting Massive Particle), such as that to be installed at the new DUSEL (Deep Underground Science and engineering laboratory) facility at Homestake in the US.

Collon, P.; Bowers, M.; Calaprice, F.; Galbiati, C.; Jiang, C. L.; Henderson, D.; Kutschera, W.; Loosli, H. H.; Pardo, R.; Paul, M.; Rehm, E.; Robertson, D.; Schmitt, C.; Scott, R.; Vondrasek, R.; Lee, H. Y.

2008-10-01

272

Investigation into the behavior of metal-argon polyatomic ions (MAr+) in the extraction region of inductively coupled plasma-mass spectrometry  

NASA Astrophysics Data System (ADS)

The abundances of metal-argon polyatomic ions (MAr+) are determined in inductively coupled plasma-mass spectrometry (ICP-MS). The ratios of MAr+ abundance to that for M+ ions are measured experimentally. These ratios are compared to expected values, calculated for typical plasma conditions using spectroscopic data. For all metals studied (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn), the measured ratios are significantly lower than the calculated ratios. Increasing the plasma potential (and thereby increasing the ion kinetic energy) by means of a homemade guard electrode with a wide gap further reduces the MAr+/M+ ratio. Implementing a skimmer cone designed for high transmission of light ions increases the MAr+ abundance. Considering this evidence, the scarcity of MAr+ ions is attributed to collision induced dissociation (CID), likely due to a shock wave at the tip of or in the throat of the skimmer cone.

Ebert, Chris H.; Witte, Travis M.; Houk, R. S.

2012-10-01

273

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES: Numerical Study on Characteristics of Argon Radio-Frequency Glow Discharge with Varying gas Pressure  

NASA Astrophysics Data System (ADS)

A one-dimensional fluid simulation on argon rf glow discharge with varying linearly gas pressure from 1 Torr to 100Torr is performed. The model based on mass conservation equations for electron and ion under diffusion and mobility approximation, and the electron energy conservation equation is solved numerically by finite volume method. The numerical results show that a uniform plasma with high density can be obtained from rf glow discharge with varying gas pressure, and the density of plasma becomes higher as the gas pressure varies from 1 Torr to 100 Torr. It is also shown that in the range of the gas pressure from 1 Torr to 100 Torr with the slower rate of varying gas pressure, higher density of plasma can be obtained.

Yu, Qian; Deng, Yong-Feng; Liu, Yue; Han, Xian-Wei

2008-07-01

274

Chromium reactive sputtering in argon–oxygen and argon–water vapor mixtures  

Microsoft Academic Search

Reactive magnetron sputtering is widely used for various protective coatings deposition. In order to control the mechanisms occurring during the sputtering, we have focused our study on the plasma. A chromium target was sputtered in two reactive gas mixtures: argon\\/oxygen and argon\\/water vapor. The argon flow and the sputtering power are kept constant. Increasing progressively the reactive gas flow, we

C. Nouvellon; J. P. Dauchot; M. Hecq; H. Cornil

2005-01-01

275

Collisional-radiative model for non-Maxwellian inductively coupled argon plasmas using detailed fine-structure relativistic distorted-wave cross sections  

NASA Astrophysics Data System (ADS)

Our recently developed collisional-radiative model which included fine-structure cross sections calculated with a fully relativistic distorted-wave method [R.K. Gangwar, L. Sharma, R. Srivastava, A.D. Stauffer, J. Appl. Phys. 111, 053307 (2012)] has been extended to study non-Maxwellian inductively coupled argon plasmas. We have added more processes to our earlier collisional-radiative model by further incorporating relativistic distorted-wave electron impact cross sections from the 3p54sJ = 0, 2 metastable states, (1s3, 1s5 in Paschen's notation) to the 3p55p (3pi) excited states. The population of various excited levels at different pressures in the range of 1-25 mTorr for an inductively coupled argon plasma have been calculated and compared with the recent optical absorption spectroscopy measurements as well as emission model results of Boffard et al. [Plasma Sources Sci. Technol. 19, 065001 (2010)]. We have also calculated the intensities of two emission lines, 420.1 nm (3p9 ? 1s5) and 419.8 nm (3p5 ? 1s4) and compared with measured intensities reported by Boffard et al. [J. Phys. D 45, 045201 (2012)]. Our results are in good agreement with the measurements.

Dipti, HASH(0x100f5750); Gangwar, Reetesh Kumar; Srivastava, Rajesh; Stauffer, Allan Daniel

2013-10-01

276

Examination of Ion Beam Acceleration in A High Power-Low Pressure and Gas Flow Rates Argon Plasma Created in the MadHeX Helicon Source  

NASA Astrophysics Data System (ADS)

The modified MadHeX experimental system consists of a Pyrex tube connected to a stainless steel chamber with an axial magnetic nozzle field, variable up to 1 kG at the source region that has been upgraded to minimize neutral reflux and reduce neutral concentrations in the chamber. A half-turn double-helix antenna is used to excite helicon waves in the source. An ion beam of energy, E = 160 eV at 500 W RF power, has been observed in a low flowing argon plasma formed in the expanding region with a 340 G magnetic field. The role of plasma positive ``self-bias'' and the effects of boundary conditions are discussed. The measured density decrease factor of 18 at 100 W RF power across the expansion region yields a higher ion acceleration and agrees with a conservation-of-flux calculation. The effect of lower flow rates and pressures, higher RF powers and magnetic field strength dependence on the ion beam acceleration, plasma potential, electron density and temperature are further explored. The axial ion velocity distribution function and temperatures at higher powers are observed by argon 668 nm laser induced fluorescence with density measurements by interferometry. The electron energy distribution and its possible non-Maxwellian tail are examined using optical emission spectroscopy (ADAS and Vlcek models).

Sung, Yung-Ta; Devinney, Michael; Scharer, John

2012-10-01

277

Ambient air particle transport into the effluent of a cold atmospheric-pressure argon plasma jet investigated by molecular beam mass spectrometry  

NASA Astrophysics Data System (ADS)

Ambient air species, which are transported into the active effluent of an atmospheric-pressure plasma jet result in highly reactive oxygen and nitrogen species (RONS). Especially for the envisaged application field of plasma medicine, these RONS are responsible for strong biological responses. In this work, the effect of ambient air transport into the effluent of an atmospheric-pressure plasma argon jet on the on-axis densities of nitrogen, oxygen and argon was investigated by means of absolutely calibrated molecular beam mass spectrometry (MBMS). According to biomedical experiments a (bottomless) Petri dish was installed in front of the MBMS. In the following, the near flow field is referring to the region close to the nozzle exit and the far flow field is referring to the region beyond that. The absolute on-axis densities were obtained by three different methods, for the near flow field with VUV-absorption technique, for the far flow field with the MBMS and the total flow field was calculated with a computational fluid dynamics (CFD) simulation. The results of the ambient air particle densities of all independent methods were compared and showed an excellent agreement. Therefore the transport processes of ambient air species can be measured for the whole effluent of an atmospheric-pressure plasma jet. Additionally, with the validation of the simulation it is possible in future to calculate the ambient species transport for various gas fluxes in the same turbulent flow regime. Comparing the on-axis densities obtained with an ignited and with a non-ignited plasma jet shows that for the investigated parameters, the main influence on the ambient air species transport is due to the increased temperature in the case when the jet is switched on. Moreover, the presence of positive ions (e.g. ArN_{2}^{+} ) formed due to the interaction of plasma-produced particles and ambient air species, which are transported into the effluent, is shown.

Dünnbier, M.; Schmidt-Bleker, A.; Winter, J.; Wolfram, M.; Hippler, R.; Weltmann, K.-D.; Reuter, S.

2013-10-01

278

Multicenter evaluation of a bilayer polymer blood collection tube for coagulation testing: effect on routine hemostasis test results and on plasma levels of coagulation activation markers.  

PubMed

We compared the results of different hemostasis tests obtained in an evacuated bilayer polymer tubes (Vacuette, Greiner Bio-One) and in a siliconized glass tubes containing the same citrate concentrations (0.109 M and 0.129 M). For that purpose, blood was collected in five centers from 60 untreated patients and from patients on oral anticoagulant (n = 168), unfractionated heparin (n = 111) or a low molecular weight derivative (n = 108). Test results obtained in polymer tubes were not significantly different from those in glass tubes, except for INR when a high ISI thromboplastin was used (p < 0.0001 for tubes containing 0.129 M sodium citrate) and for APTT (p < 0.05 for both citrate concentrations). However, these differences had no clinical relevance (Bland-Altman analysis). In addition, no effect of aging of the polymer tubes on the test results could be demonstrated. The plasma levels of F1+2 and TAT, measured in a subset of 30 untreated patients, were significantly lower when blood was collected in polymer than in glass tubes, for both citrate concentrations. These results suggest that samples collected into the Vacuette polymer tubes allow accurate routine hemostasis testing both in untreated patients and in patients on traditional anticoagulant treatment during the whole shelf-life indicated by the manufacturer. PMID:17102648

Toulon, Pierre; Aillaud, Marie-Françoise; Arnoux, Dominique; Boissier, Elodie; Borg, Jeanne-Yvonne; Gourmel, Céline

2006-11-01

279

Acetylene-argon plasmas measured at an rf-biased substrate electrode for diamond-like carbon deposition: II. Ion energy distributions  

NASA Astrophysics Data System (ADS)

Ion energy distributions (IEDs) have been determined at the radio frequency (rf)-biased electrode in an inductively coupled acetylene-argon plasma for various substrate bias voltages and frequencies under conditions suitable for diamond-like carbon (DLC) and polymer-like film deposition. These are compared with those obtained at a capacitively coupled plasma grounded wall. In the former, for pressures <25 mTorr, the IEDs exhibit bimodal structures with peak separation values that follow the expected voltage and frequency dependences. At higher pressures, 120 mTorr, the bimodal structure is replaced by a single peak. For all conditions the dominant ion is Ar+ or ArH+ despite the set flow ratio of C2H2 : Ar of 2 : 1 and this can be attributed to the high electron dissociation of the parent molecule. DLC films indicate a peak hardness at an ion energy of around 90 eV and a very sharp fall in hardness is noted beyond this value. This is similar to the observed sp3-bond formation in hydrogen-free tetrahedral amorphous carbon or bias-sputtered films. However, due to the lack of carbon-based ions, an alternative mechanism is likely based on argon knock-on implantation of surface adsorbed carbon species. The results have shown that the use of high-frequency bias or bias harmonics may lead to much narrower IEDs. .

Baby, A.; Mahony, C. M. O.; Lemoine, P.; Maguire, P. D.

2011-02-01

280

Numerical study of the effect of gas temperature on the time for onset of particle nucleation in argon-silane low-pressure plasmas  

NASA Astrophysics Data System (ADS)

Particle nucleation in silane plasmas has attracted interest for the past decade, both due to the basic problems of plasma chemistry involved and the importance of silane plasmas for many applications. A better understanding of particle nucleation may facilitate the avoidance of undesirable particle contamination as well as enable the controlled production of nanoparticles for novel applications. While understanding of particle nucleation has significantly advanced over the past years, a number of questions have not been resolved. Among these is the delay of particle nucleation with an increasing gas temperature, which has been observed in experiments in argon-silane plasmas. We have developed a quasi-one-dimensional model to simulate particle nucleation and growth in silane containing plasmas. In this paper we present a comparative study of the various effects that have been proposed as explanations for the nucleation delay. Our results suggest that the temperature dependence of the Brownian diffusion coefficient is the most important effect, as diffusion affects both the loss rate and growth rate of particles.

Bhandarkar, Upendra; Kortshagen, Uwe; Girshick, Steven L.

2003-06-01

281

Reduction of Fresh Frozen Plasma Requirements by Perioperative Point-of-Care Coagulation Management with Early Calculated Goal-Directed Therapy  

PubMed Central

Background Massive bleeding and transfusion of packed red blood cells (PRBC), fresh frozen plasma (FFP) and platelets are associated with increased morbidity, mortality and costs. Patients and Methods We analysed the transfusion requirements after implementation of point-of-care (POC) coagulation management algorithms based on early, calculated, goal-directed therapy with fibrinogen concentrate and prothrombin complex concentrate (PCC) in different perioperative settings (trauma surgery, visceral and transplant surgery (VTS), cardiovascular surgery (CVS) and general and surgical intensive care medicine) at 3 different hospitals (AUVA Trauma Centre Salzburg, University Hospital Innsbruck and University Hospital Essen) in 2 different countries (Austria and Germany). Results In all institutions, the implementation of POC coagulation management algorithms was associated with a reduction in the transfusion requirements for FFP by about 90% (Salzburg 94%, Innsbruck 88% and Essen 93%). Furthermore, PRBC transfusion was reduced by 8.4–62%. The incidence of intraoperative massive transfusion (?10 U PRBC) could be more than halved in VTS and CVS (2.56 vs. 0.88%; p < 0.0001 and 2.50 vs. 1.06%; p = 0.0007, respectively). Platelet transfusion could be reduced by 21–72%, except in CVS where it increased by 115% due to a 5-fold increase in patients with dual antiplatelet therapy (2.7 vs. 13.7%; p < 0.0001). Conclusions The implementation of perioperative POC coagulation management algorithms based on early, calculated, goal-directed therapy with fibrinogen concentrate and PCC is associated with a reduction in the transfusion requirements for FFP, PRBC and platelets as well as with a reduced incidence of massive transfusion. Thus, the limited blood resources can be used more efficiently.

Gorlinger, Klaus; Fries, Dietmar; Dirkmann, Daniel; Weber, Christian F.; Hanke, Alexander A.; Schochl, Herbert

2012-01-01

282

Coagulation in sepsis  

Microsoft Academic Search

Coagulation abnormalities, ranging from a simple fall in platelet count to full-blown disseminated intravascular coagulation, are a common occurrence in critically ill patients and have been associated with increased mortality. In sepsis, activation of the extrinsic coagulation pathway by tissue factor induces increased coagulation, and simultaneous depression of the inhibitory mechanisms of coagulation, and suppression of the fibrinolytic system results

André Amaral; Steven M. Opal; Jean-Louis Vincent

2004-01-01

283

Mechanism of Blood Coagulation by Non-Thermal Atmospheric Pressure Dielectric Barrier Discharge  

Microsoft Academic Search

Summary form only given. Blood coagulation by direct contact of nonthermal atmospheric pressure Dielectric Barrier Discharge (DBD) plasma in vitro has been reported previously. This discharge appears to promote rapid blood coagulation by enhancing natural coagulation processes. However, there is no detailed understanding of the specific mechanisms by which this nonthermal plasma coagulates blood. In this paper we investigate few

S. Kalghatgi; G. Fridman; M. Balasubramanian; A. Brooks; V. Vasilets; A. Fridman; A. Gutsol; G. Friedman

2007-01-01

284

Effects of radio-frequency driving power, gas pressure, and nitrogen seeding on the transition dynamics in argon inductively coupled plasmas  

SciTech Connect

The influences of rf driving power, neutral gas pressure, and nitrogen seeding on the electrostatic-to-electromagnetic (E-H) mode transition dynamics in radio-frequency argon inductively coupled plasmas (ICPs) in a pressure range of 50-100 kPa are investigated, both experimentally and theoretically. The E-H mode transition dynamics and its characteristic transition time scale are investigated by observing the high-speed imaging (13 500 fps) as well as the temporal change of plasma loading impedance. The experimental results reveal that the E-H mode transition time is not fixed at any operating conditions rather it depends on some important parameters such as the rf driving power, neutral gas pressure, gas type. It is found that the E-H mode transition time depends on the unique parameter E{sub {theta}}/p; the so-called effective induced electric field, rather than the independent parameter: the rf power or neutral gas pressure. It is also found that longer E-H mode transition time is required to ignite the high-pressure Ar-N{sub 2} plasmas with a 2.5%-10% N{sub 2} seeding than that of pure Ar plasmas with the same operating conditions. The experimental results are compared with that of the recently developed theoretical models, and a good agreement is found between them.

Razzak, M. Abdur; Takamura, Shuichi; Uesugi, Yoshihiko [Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Department of Electrical and Electronic Engineering, Kanazawa University 2-40-20 Kodatsuno, Ishikawa 920-8667 (Japan)

2004-11-01

285

Interactions among Hageman factor (HG, Factor XII), plasma thromboplastin antecedent (PTA, Factor XI), plasma prekallikrein (PK, Fletcher factor) and high molecular weight kininogen (HMW-K, Fitzgerald factor) in blood coagulation.  

PubMed

Studies of plasmas from individuals with Hageman trait (factor XII deficiency), plasma thromboplastin antecedent (PTA, factor XI) deficiency, Fletcher trait (plasma prekallikrein deficiency) and Fitzgerald trait (high molecular weight-kininogen deficiency) have revealed the importance of these proteins in blood coagulation. The interactions among them, however, are not fully elucidated. We have studied these reactions by two different approaches. (1) In a purified system, high molecular weight kininogen was absolutely required for activation of PTA by HF and ellagic acid (EA). The yield of activated PTA was proportional to the amount of HF, HMW-K, and PTA in the mixtures, suggesting that these three proteins may form a complex in the presence of EA. (2) In experiments with whole plasma, we took advantage of the adsorption of EA to Sephadex gels. When normal plasma or plasma deficient in HF, PK, HMW-K or PTA was exposed to Sephadex-EA and was separated by centrifugation, each supernatant plasma except that deficient in HF shortened the prolonged partial thromboplastin time (PTT) of HF-deficient plasma. Plasma simultaneously depleted of HMW-K, PK and PTA also shortened the PTT of HF-deficient plasma and of plasma depleted of HF and PK, but had virtually no procoagulant effect upon the PTT of plasma depleted of HF and MHW-K. Thus, exposure of HF in plasma to Sephadex-EA appeared to generate a clot-promoting form of HF in the absence of other clotting factors, but its expression required the presence of HMW-K. PMID:517254

Saito, H; Ratnoff, O D

1979-01-01

286

Comparison of amino acid sequence of bovine coagulation Factor IX (Christmas Factor) with that of other vitamin K-dependent plasma proteins.  

PubMed Central

The amino acid sequence of bovine blood coagulation Factor IX (Christmas Factor) is presented and compared with the sequences of other vitamin K-dependent plasma proteins and pancreatic trypsinogen. The 416-residue sequence of Factor IX was determined largely by automated Edman degradation of two large segments, containing 181 and 235 residues, isolated after activating Factor IX with a protease from Russell's viper venom. Subfragments of the two segments were produced by enzymatic digestion and by chemical cleavage of methionyl, tryptophyl, and asparaginyl-glycyl bonds. Comparison of the amino acid sequences of Factor IX, Factor X, and Protein C demonstrates that they are homologous throughout. Their homology with prothrombin, however, is restricted to the amino-terminal region, which is rich in gamma-carboxyglutamic acid, and the carboxyl-terminal region, which represents the catalytic domain of these proteins and corresponds to that of pancreatic serine proteases.

Katayama, K; Ericsson, L H; Enfield, D L; Walsh, K A; Neurath, H; Davie, E W; Titani, K

1979-01-01

287

Hormones of hypothalamic-pituitary-thyroid axis are significant regulators of synthesis and secretion of vitamin K-dependent plasma coagulation factors.  

PubMed

Present data about hormonal regulation of haemostasis are often contradictory and are mostly based on clinical observations. The aim of the current research is to study the effects of the hormones of hypothalamic-pituitary-thyroid (HPT) axis on plasma levels (i.e. on the synthesis and secretion) of vitamin K-dependent coagulation factors in rats. The study was carried out on 65 male Wistar rats, divided into five groups. The animals were injected subcutaneously (s.c.) once daily for three consecutive days as follows: the first group was injected with Thyrotropin releasing hormone (TRH), in a dose of 0.06 mg/kg b.w.; the second group by Thyroid stimulating hormone (TSH), with a dose of 1 MU/kg b.w., the third and the fourth group respectively with Liothyroninum (Triiodothyronin ? T3) and Levothyroxinum (Thyroxin ? T4) with a dose of 0.08 mg/kg b.w. each. The control group rats were injected with saline (the solvent of the hormones), following the same schedule and volume per kg b.w. The necessary quantity of blood was acquired by a cardiac puncture under ether narcosis, and antigen levels of plasma factors II, VII, IX and X (FII:Ag, FVII:Ag, FIX:Ag and FX:Ag) were determined by ELISA kits (Diagnostica Stago, France). TRH, TSH, T3 and T4 significantly decreased the plasma antigen levels of FII and FVII (p<0.001). TRH, T3 and TSH reduced significantly FIX:Ag level( p<0.001 for TRH and T3 and p<0.05 for TSH) while T4 did not exert significant changes ( p>0.05). FX:Ag level was also significantly reduced by TRH, T3 (p<0.001), TSH and T4 (p<0.01). Plasma levels of vitamin K-dependent coagulation factors F??:Ag, FV??:Ag, F??:Ag and F?:Ag are significantly reduced under the influence of the hormones of hypothalamic-pituitary-thyroid axis which signifies their decreased synthesis and secretion. T4 does not induce substantial changes in FIX:Ag plasma level. PMID:21382270

Negrev, N; Tashev, R; Radev, R; Anogeianaki, A; Ivanova, M

288

The Plasma Etching Characterization of Silicon Dioxide and Silicon Using Plasma-Surface Reaction Parameters with Carbon Tetrafluoride/oxygen/argon/fluoroform Plasmas.  

NASA Astrophysics Data System (ADS)

The plasma etching of SiO_2 and Si and the plasma diagnostics have been carried out in CF_4/O_2/Ar/CHF _3 plasmas in both ECR and RIE tools. In the ECR etching, it is found that the etch rate of both SiO_2 and Si can be partitioned into two regimes by a critical value of rm n_{F}/(J_{i}E_ {i}), the ratio of the F-atom density to the ion energy flux. The critical value of rm n_{F}/(J_{i}E _{i}) for Si is higher than that for SiO_2. For rm n_{F}/(J_{i}E_ {i}) higher than the critical value, SiO _2 etch rate linearly increases with the ion energy flux, while Si etch rate shows a nonlinear increase with the ion energy flux because of the ion-neutral synergism near the boundary of the two regimes. For rm n_{F}/(J_{i}E _{i}) lower than the critical value, both SiO_2 and Si etch rates linearly increase with the F-atom density. In the RIE, rm n_{F}/(J_{i}E _{i}) higher than the critical value, the SiO_2 etch rate linearly increases with the ion energy flux, the same as in the ECR etching. However, the SiO_2 etch rate in the RIE is much lower than that in the ECR etching at the same ion energy flux due to the higher polymerization in the RIE. A symmetric rate model is proposed for fluorocarbon -based plasma etching of SiO_2 and Si including the effects of ion energy flux, etching species flux, and polymerization species flux. When there is no polymerization, the symmetric rate model gives the same plasma etch rate as that given by the ion-neutral synergism. When there is no etching, the symmetric rate model gives a deposition rate for plasma enhanced chemical vapor deposition (PECVD). All the ECR etching results are explained by the symmetric model in the case of no polymerization. The RIE SiO _2 etch rates are explained to be the ECR SiO_2 etch rate modified by a factor of [ 1-C({n_{CF2 }over n_{F}})^2 ], which is a simplified case of the symmetric rate model, where rm n_ {CF2} is CF_2 density, n_{rm F} is F-atom density, and C is a constant.

Ding, Ji.

289

The current status of coagulation.  

PubMed

In 1964, the events of haemostasis were organized into the intrinsic and extrinsic pathways by the cascade/waterfall hypothesis, with primary physiological importance being given to the intrinsic pathway. Recent experimental evidence, as well as information about the clinical course of patients with various coagulation factor deficiencies, indicates a more prominent role for tissue factor. Rediscovery of the plasma protease inhibitor, tissue factor pathway inhibitor, and new information about the activation of factor XI have supported a revised theory of coagulation. PMID:7741998

Luchtman-Jones, L; Broze, G J

1995-02-01

290

Protective Effects of Fresh Frozen Plasma on Vascular Endothelial Permeability, Coagulation, and Resuscitation After Hemorrhagic Shock Are Time Dependent and Diminish Between Days 0 and 5 After Thaw  

PubMed Central

Background Clinical studies have shown that resuscitation with fresh frozen plasma (FFP) is associated with improved outcome after severe hemorrhagic shock (HS). We hypothesized that in addition to its effects on hemostasis, FFP has protective and stabilizing effects on the endothelium that translate into diminished endothelial cell (EC) permeability and improved resuscitation in vivo after HS. We further hypothesized that the beneficial effects of FFP would diminish over 5 days of routine storage at 4°C. Methods EC permeability was induced by hypoxia and assessed by the passage of 70-kDa Dextran between monolayers. Thrombin generation time and coagulation factor levels or activity were assessed in FFP. An in vivo rat model of HS and resuscitation was used to determine the effects of FFP on hemodynamic stability. Results Thawed FFP inhibits EC permeability in vitro by 10.2-fold. Protective effects diminish (to 2.5-fold) by day 5. Thrombin generation time is increased in plasma that has been stored between days 0 and 5. In vivo data show that day 0 FFP is superior to day 5 FFP in maintaining mean arterial pressure in rats undergoing HS with resuscitation. Conclusion Both in vitro and in vivo studies show that FFP has beneficial effects on endothelial permeability, vascular stability, and resuscitation in rats after HS. The benefits are independent of hemostasis and diminish between days 0 and 5 of storage.

Pati, Shibani; Matijevic, Nena; Doursout, Marie-Francoise; Ko, Tien; Cao, Yanna; Deng, Xiyun; Kozar, Rosemary A.; Hartwell, Elizabeth; Conyers, Jodie; Holcomb, John B.

2011-01-01

291

Applications of Optical Emission Spectroscopy with Inductively Heated Argon Plasma Torch in the Analysis of Environmental Materials.  

National Technical Information Service (NTIS)

This paper describes the application of inductively coupled plasma atomic emission spectrometry as a method for the quantitative analysis of elements in environmental samples. Systematic investigations were undertaken using a sequentially working ICP devi...

W. Berneike

1987-01-01

292

Spectroscopic diagnostic of an argon-hydrogen RF inductive thermal plasma torch at atmospheric pressure used for silicon hydrogenation  

Microsoft Academic Search

Hydrogenation of silicon materials has great advantages for its photovoltaic properties and is the key to elimination of crystalline defects during basaltic growth of the crystal. It is therefore interesting to characterize the plasma by optical emission spectroscopy methods in order to study hydrogenation of silicon particles during their treatment by an inductive thermal plasma burning in the Ar–H2 mixture.Excited

F. Bourg; S. Pellerin; D. Morvan; J. Amouroux; J. Chapelle

2002-01-01

293

Anode Attachment and Received Heat of Argon Torch Plasma with High Lateral Air as Function of Current  

NASA Astrophysics Data System (ADS)

The torch plasma arc has useful characteristics of high energy and high current. And the mode of torch plasma arc can be flexible, even if the arcs is exposed to the lateral gas. In this paper, we measured the input power, heat power, and heat efficiency of the torch plasma arc to the anode in order to know the current effect on the anode attachment of plasma torch arc with the high lateral air velocity, varying from 0 to 80m/s at the plasma Ar flow rate of 12slm. As a result, the input power increases with lateral gas velocity such as about 8,000W to 16,000W and the heat efficiency decreases with the lateral gas velocity such as about 50% to 25% at the current I = 150A and appearance plasma length La = 1cm. These results could be applied to providing the electrical power from the ground to high-speed mobiles, v.v., and to reducing an anode surface erosion by the anode spot movement.

Ishikawa, Shuhei; Beppu, Takuya; Iwao, Toru; Inaba, Tsuginori

294

Plasma Levels of Phospholipase A2-IIA in Patients with Different Types of Malignancies: Prognosis and Association with Inflammatory and Coagulation Biomarkers.  

PubMed

It is well-known that the plasma level of group IIA phospholipase A2 (sPLA2-IIA) is increased in patients with malignant diseases, but whether the up-regulated enzyme expression is directly related to tumorigenesis or a consequence of tumor-associated inflammation remains unresolved. In this study we analyzed circulating levels of sPLA2-IIA, C-reactive protein (CRP), fibrinogen, factor VIII (FVIII), von Willebrand factor (vWF), and antithrombin as biomarkers of inflammation and coagulation in patients with various types of malignancies. Underlying tumor entities were lung, esophageal, gastric, pancreatic, colorectal, head and neck, and hepatocellular carcinomas as well as multiple myeloma and non-Hodgkin's lymphoma. Plasma levels of sPLA2-IIA are shown to be markedly increased in all types of analysed malignancies in comparison to the normal range (22.8?±?4.5 ?g/L versus <1.9 ?g/L). Levels of sPLA2-IIA correlate positively with CRP (p?4 ?g/L) of this enzyme. In conclusion, the study shows that the measurement of plasma sPLA2-IIA levels has prognostic values in patients with different types of malignancies. The association of sPLA2-IIA levels with CRP, fibrinogen, FVIII, and vWF levels supports the importance of inflammatory processes for the up-regulation of sPLA2-IIA during cancer progression. PMID:23722320

Menschikowski, Mario; Hagelgans, Albert; Schuler, Ulrich; Froeschke, Susanne; Rosner, Andrea; Siegert, Gabriele

2013-06-01

295

One- and two-dimensional density and temperature measurements of an argon-neon Z-pinch plasma at stagnation  

SciTech Connect

In order to benchmark and improve current 2D radiation magnetohydrodynamic (MHD) models of Z-pinch plasmas, we have performed experiments which characterize the plasma -conditions at stagnation. In the experiments the SATURN pulsed power facility at Sandia National Laboratory was used to create an imploding -Ar-Ne plasma. An absolutely calibrated, high resolution space- and time- resolving Johann crystal spectrometer was used to infer the electron temperature Te from the slope of the hydrogenlike Ne free-bound continuum, and the ion density ni from the Stark broadening of the Ar heliunlike Rydberg series. 2D electron temperature profiles of the plasma are obtained from a set of imaging crystals also focused on the Ne free-bound continuum. We shot two types of gas nozzles in the experiment, annular and uniform fill which varies the amount of mass in the plasma. 2D local thermodynamic equilibrium (LTE) and non-LTE MM models predict a radiating region denser and cooler than measured.

Wong, K.L.; Springer, P.T.; Hammer, J.H.; Iglesias, C.A.; Osterheld, A.L.; Foord, M.E.; Bruns, H.C.; Emig, J.A.; Deeney, C.

1996-10-01

296

The influence of the Stark effect on the shape of He-like argon lines in a dense plasma  

SciTech Connect

We interpret the relative intensities and widths of ArXVII lines in a dense plasma including the Stark effect of electromagnetic fields. For many elements the wavelength of the forbidden line 2{sup 1}S{sub 0}-1{sup 1}S{sub 0} is almost equal to that of intercombination y-line (2{sup 3}P{sub 1}-1{sup 1}S{sub 0}). A strong enough electric field can cause the forbidden line intensity to become high enough to have a visible effect on the intensity of the intercombination line. This paper calculates the intensity of the resonance, intercombination, and forbidden lines versus the strength of the electric field, including the shift of the n = 2 levels in ArXVII. A collisonal-radiative model simulates the ArXVII lines in a dense plasma with a electric field, demonstrating that an electric field with E = 10{sup 10} V/cm has the same effect on line shape as plasma opacity. Good agreement is obtained with ArXVII spectra emitted by a Z-pinch, with peak current 500 kA. Since the intensities of intercombination and resonance lines are widely used to determine plasma parameters, the present study is relevant to the applicability range of existing methods, and may show the way to measure strong electric fields. We also discuss the reasons for the presence of strong macroscopic electric fields in a plasma.

Baronova, E. O.; Sholin, G. V.; Vikhrev, V. V. [RRC Kurchatov Institute, Moscow (Russian Federation); Jakubowski, L. [A. Soltan Institute for Nuclear Studies, Swierk n. Warsaw (Poland)

2008-03-19

297

Reflectance as an indirect measurement of the extent of laser-induced coagulation  

Microsoft Academic Search

Two-dimensional reflectance images and surface thermal distributions were recorded during argon laser induced coagulation. During laser irradiation, coagulated egg yolk formed a white lesion. The whiteness, or reflectance caused by backscattering of light from the forming lesion, would be measured after a short delay from the onset of laser irradiation. In the experiments, which covered exposure times from 4.5 to

Y. Yang; M. S. Markow; W. S. Weinberg; A. J. Welch

1990-01-01

298

Clinical applications of the Argon and carbon dioxide lasers in dermatology and plastic surgery  

Microsoft Academic Search

Since the 1960's, thousands of skin and soft tissue malformations have been treated with the Argon and carbon dioxide lasers. The Argon laser, emitting blue-green light, is very useful for treating port wine hemangiomas and other cutaneous vascular abnormalities; it has also been applied to a variety of nonvascular skin lesions. Its mechanism of action is essentially heat coagulation.

Morton R. Maser; David B. Apfelberg; Harvey Lash

1983-01-01

299

Analysis of the generation and inhibition of activated coagulation factor X in pure systems and in human plasma.  

PubMed

The overall generation and inhibition of human factor Xa have been studied in pure systems and plasma to determine the kinetic characteristics of inhibition during factor Xa generation. Generation curves were measured amidolytically in a pure system containing factor X and antithrombin, which was activated with the factor X-activating enzyme of Russell's viper venom (RVV-X). The measured change in factor Xa level with time was fitted to a 3-parameter 2-exponential model to determine apparent first-order rates of inhibition. With antithrombin at 4.5 microM, the inhibition rate constant thus obtained was very close to the known rate of inhibition of exogenous enzyme. Factor Xa generation curves were also analyzed in plasma; however, to reduce interference in the assay of thrombin, congenitally prothrombin-deficient plasma was used containing 0.5 microM D-Phe-Pro-Arg-chloromethylketone. In plasma, factor Xa generated in the presence of phospholipid and Ca2+ ions by RVV-X, factor IXa, or tissue factor was inhibited more slowly than exogenous enzyme. The reduction was particularly severe with tissue factor activation, where the rate was 0.04-0.06 min-1. This protection by tissue factor was also observed in pure systems and apparently required factor VII. PMID:3722168

Jesty, J

1986-07-01

300

Ionization of elements in medium power capacitively coupled argon plasma torch with single and double ring electrodes.  

PubMed

A medium power, low Ar consumption capacitively coupled plasma torch (275 W, 0.4 L min-1) with molybdenum tubular electrode and single or two ring electrodes in non-local thermodynamic equilibrium (LTE) was characterized with respect to its ability to achieve element ionization. Ionization degrees of Ca, Mg, Mn and Cd were determined from ionic-to-atomic emission ratio and ionization equilibrium according to Saha's equation. The ionization degrees resulted from the Saha equation were higher by 9-32% than those obtained from spectral lines intensity in LTE regime and closer to reality. A linear decrease of ionization with increase of ionization energy of elements was observed. Plasma torch with two ring electrodes provided higher ionization degrees (85 ± 7% Ca, 79 ± 7% Mn, 80 ± 7% Mg and 73 ± 8% Cd) than those in single ring arrangement (70 ± 6% Ca, 57 ± 7% Mn, 57 ± 8% Mg and 42 ± 9% Cd). The Ca ionization decreased linearly by up to 79 ± 4% and 53 ± 6% in plasma with two ring electrodes and single ring respectively in the presence of up to 400 µg mL-1 Na as interferent. The studied plasma was effective in element ionization and could be a potential ion source in mass spectrometry. PMID:24061253

Ponta, Michaela; Frentiu, Maria; Frentiu, Tiberiu

2012-06-01

301

Numerical solution of the spatially inhomogeneous Boltzmann equation and verification of the nonlocal approach for an argon plasma  

Microsoft Academic Search

The spatially dependent description of the electron kinetics is of vital interest for the modeling of complete plasma devices. A possible method of dealing with this problem is by the solution of the Boltzmann equation accounting for the spatial inhomogeneity. This approach can be a complicated task. On the other hand, this method may be much more efficient than the

C. Busch; U. Kortshagen

1995-01-01

302

Argon/UF6 Plasma Exhaust Gas Reconstitution Experiments Using Preheated Fluorine and on-Line Diagnostics.  

National Technical Information Service (NTIS)

The feasibility of employing a flowing, high-temperature, pure fluorine/UF6 regeneration system to efficiently convert a large fraction of the effluent plasma exhaust back to pure UF6 was demonstrated. The custom built T.O.F. mass spectrometer sampling sy...

W. C. Roman

1979-01-01

303

Direct liquid sample introduction for flow injection analysis and liquid chromatography with inductively coupled argon plasma spectrometric detection  

Microsoft Academic Search

The coupling of flow injection analysis (FIA) or high-performance liquid chromatography (HPLC) techniques to inductively coupled plasma atomic emission spectrometry (ICP-AES) offers new and attractive approaches for the determination of elemental concentrations in a wide variety of sample matrices. One of the most attractive features that FIA offers is a rapid and precise means of automating sample introduction into an

Kimberly E. Lawrence; Gary W. Rice; Velmer A. Fassel

1984-01-01

304

Study of an argon–hydrogen RF inductive thermal plasma torch used for silicon deposition by optical emission spectroscopy  

Microsoft Academic Search

The hydrogenation of silicon deposited on a substrate for photovoltaic applications has been obtained by a plasma torch. This method shows a great advantage and leads to the improvement of the electronic properties of the material. The hydrogenation of silicon allows the crystallographic defects elimination (dislocations, dangling bonds) which leads to an increase of the diffusion length.In order to understand

F Bourg; S Pellerin; D Morvan; J Amouroux; J Chapelle

2002-01-01

305

Characterization of the Gene for the a Subunit of Human Factor XIII (Plasma Transglutaminase), a Blood Coagulation Factor  

Microsoft Academic Search

Factor XIII (plasma transglutaminase, fibrin stabilizing factor) is a glycoprotein that circulates in blood as a tetramer (a2b2) consisting of two a and two b subunits. The primary structures of the a and b subunits of human factor XIII have been reported by a combination of cDNA cloning and amino acid sequence analysis. To establish the gene structure of the

Akitada Ichinose; Earl W. Davie

1988-01-01

306

Discharge-Mode Transition in Jet-Type Dielectric Barrier Discharge Using Argon/Acetone Gas Flow Ignited by Small Helium Plasma Jet  

NASA Astrophysics Data System (ADS)

A discharge-mode transition in a jet-type dielectric barrier discharge (DBD) was triggered by a small fraction of acetone vapor added to an argon (Ar) gas flow at atmospheric pressure. In order to trigger a stable discharge in the Ar/acetone gas flow with a relatively small applied voltage, we used an additional small plasma jet using a He gas flow on the side of the main flow. The transition from filamentary to glow like discharge modes took place upon increasing the acetone-vapor ratio, with the transition occurring at an acetone content of approximately 0.3 vol %. We compared discharge currents, optical emission spectra, and deposited materials on the substrate in each discharge mode to characterize the discharge phenomena. The experimental results clearly indicate that the characteristics of the jet-type DBD show nonlinear dependence on the acetone-vapor ratio, especially around the transition to the discharge mode. It was also found by microscopic observations that the surface morphologies of the deposited materials were completely different in the filamentary and glow like modes.

Urabe, Keiichiro; Yamada, Keitaro; Sakai, Osamu

2011-11-01

307

Argon Analytical Procedures for Potassium-Argon Dating.  

National Technical Information Service (NTIS)

A manual for the argon analytical methods involved in potassium-argon geochronology, including: i) operating procedures for the ultra-high vacuum argon extraction/purification equipment for the analysis of nanolitre quantities of radiogenic argon in rocks...

J. E. Gabites C. J. Adams

1981-01-01

308

Neonatal coagulation problems  

Microsoft Academic Search

Bleeding problems often occur during the neonatal period. Although thrombocytopenia is the most common cause, coagulation problems often occur, and the two problems may co-exist. The causes, diagnosis, and management of coagulation problems in newborn infants are reviewed.

E A Chalmers

2004-01-01

309

Characterization of the gene for the a subunit of human factor XIII (plasma transglutaminase), a blood coagulation factor  

SciTech Connect

Factor XIII (plasma transglutaminase, fibrin stabilizing factor) is a glycoprotein that circulates in blood as a tetramer (a{sub 2}b{sub 2}) consisting of two a and two b subunits. The primary structures of the a and b subunits of human factor XIII have been reported by a combination of cDNA cloning and amino acid sequence analysis. To establish the gene structure of the a subunit for factor XIII, several human genomic libraries were screened by using the cDNA encoding the a subunit as a probe. Among {approx}5 {times} 10{sup 7} recombinant phage, 121 have been shown to contain an insert encoding a portion of the a subunit. Twenty-five unique clones were than characterized by restriction mapping, Southern blotting, and DNA sequencing. Overlapping clones encoding the a subunit of factor XIII span >160 kilobases. DNA sequence analysis revealed that the activation peptide released by thrombin, the active site cysteine region, the two putative calcium-binding regions, and the thrombin cleavage site leading to inactivation are encoded by separate exons. This suggest that the introns may separate the a subunit into functional and structural domains. A comparison of the amino acid sequence deduced from the genomic DNA sequence with those deduced from cDNA or determined by amino acid sequence analysis of the plasma and placental proteins revealed apparent amino acid polymorphisms in six positions of the polypeptide chain of the a subunit.

Ichinose, A.; Davie, E.W. (Univ. of Washington, Seattle (USA))

1988-08-01

310

Optogalvanic spectra in the near ultraviolet and visible regions and the time-resolved laser optogalvanic waveforms of argon and neon and their usefulness in the analysis of direct current plasmas  

NASA Astrophysics Data System (ADS)

The rate of ionization of an atomic or molecular species in a discharge plasma displays a momentary increase or decrease when it is irradiated with illumination resonant with a transition of that species. Such a rate of ionization change can be detected as a transitory current variation known as the optogalvanic effect (OGE). The optogalvanic (OG) spectra of neon and argon in the visible and near ultraviolet (UV) regions were recorded using a pulsed Nd:YAG-pumped tunable dye laser to irradiate either an iron-neon hollow cathode discharge lamp or an iron-neon-argon see-through hollow cathode discharge lamp. The wavelength of the atomic OG spectra was cross-calibrated using the rotationally-resolved laser-induced fluorescence (LIF) spectrum of the hydroxyl (OH) radical. Previously unreported OG transitions, especially for argon, were identified and assigned using the J-L coupling scheme. Time-resolved laser optogalvanic (LOG) waveforms of specific neon and argon transitions were analyzed using a promising model of collisional ionization based upon the population distribution of the atomic species in the discharge plasma of a hollow cathode lamp (HCL) found in the literature. With the aid of a non-linear least-squares fit program written in Fortran code, the waveform parameters were determined by fitting a theoretical model to the observed experimental data. Several of these parameters were found proportional to the electron collisional cross sections associated with the states involved in the transition. The data was consistent with the theory that collisional ionization is the dominant factor in producing the OGE signal in the low current region of 0.2-3.0 mA, although other processes were not ruled out. Such a detailed analysis of the physics of the time-resolved LOG waveforms yielded quantitative information on the rates of excited state collisional processes in the gas discharge plasma.

Major, Helen E.

311

Etch product dynamics of polyphenylene oxide laminates using a carbon tetra fluoride/oxygen/argon downstream microwave plasma  

NASA Astrophysics Data System (ADS)

A downstream microwave plasma etcher has been constructed to study the etch dynamics of polyphenylene oxide laminates (PPO) using CF4/O 2/Ar reactant gases. The results of optical emission spectroscopy indicate that both atomic fluorine and atomic oxygen participate in the etching process. Quantitative analysis of downstream etch products based on the real time measurement of molecular-beam mass spectrometry shows major etch products of CO, CO 2 and HF. A linear correlation between weight loss measurements of PPO laminates and the integration of CO and CO2 etch products with respect to processing time suggests that the study of etch dynamics can be achieved. Additionally, XPS results show more fluorinated carbons on the surface etched with 30% CF4 than with 10% CF4. The etch rate changes more with processing time as CF4% increases. The dynamic reduction in rate becomes significant at CF4 ? 10% for a pressure of 0.2 torr, and CF4 ? 20% for 0.5 and 0.8 torr. At temperatures of 50 to 180°C, the etching process exhibits an activation energy of 0.80 cal/mole and shows similar dynamics. The average etch rate increases with flow rate from 30 to 60 sccm. A greater reduction in etch rate with process time is also found. CO is the major etch product at low CF4% while CO2 dominates at high CF4. It is proposed that CO is the primary product of nonfluorinated polymers while CO2 could be produced by recombination of CO and O through fluorinated surfaces. A one-dimensional model has been developed to analyze the concentrations of reactive species in the downstream microwave plasma etcher. Electron impact dissociation reactions, homogeneous chemistry and wall recombination reactions are included. The general experimental trends are predicted by the model. A three-step mechanism (initiation, etching and passivation) is used to develop an unsteady state model for the surface kinetics. The reaction rate constants are estimated using computed concentrations of reactive precursors based on the one-dimensional model. The values of constants suggest that the initial etch rate is controlled by the initiation and etching steps while the dynamic reduction is governed by the passivation step.

Hsu, Chia-Chang

312

Transfusion in trauma: thromboelastometry-guided coagulation factor concentrate-based therapy versus standard fresh frozen plasma-based therapy  

PubMed Central

Introduction Thromboelastometry (TEM)-guided haemostatic therapy with fibrinogen concentrate and prothrombin complex concentrate (PCC) in trauma patients may reduce the need for transfusion of red blood cells (RBC) or platelet concentrate, compared with fresh frozen plasma (FFP)-based haemostatic therapy. Methods This retrospective analysis compared patients from the Salzburg Trauma Centre (Salzburg, Austria) treated with fibrinogen concentrate and/or PCC, but no FFP (fibrinogen-PCC group, n = 80), and patients from the TraumaRegister DGU receiving ? 2 units of FFP, but no fibrinogen concentrate/PCC (FFP group, n = 601). Inclusion criteria were: age 18-70 years, base deficit at admission ?2 mmol/L, injury severity score (ISS) ?16, abbreviated injury scale for thorax and/or abdomen and/or extremity ?3, and for head/neck < 5. Results For haemostatic therapy in the emergency room and during surgery, the FFP group (ISS 35.5 ± 10.5) received a median of 6 units of FFP (range: 2, 51), while the fibrinogen-PCC group (ISS 35.2 ± 12.5) received medians of 6 g of fibrinogen concentrate (range: 0, 15) and 1200 U of PCC (range: 0, 6600). RBC transfusion was avoided in 29% of patients in the fibrinogen-PCC group compared with only 3% in the FFP group (P< 0.001). Transfusion of platelet concentrate was avoided in 91% of patients in the fibrinogen-PCC group, compared with 56% in the FFP group (P< 0.001). Mortality was comparable between groups: 7.5% in the fibrinogen-PCC group and 10.0% in the FFP group (P = 0.69). Conclusions TEM-guided haemostatic therapy with fibrinogen concentrate and PCC reduced the exposure of trauma patients to allogeneic blood products.

2011-01-01

313

Inter-chain disulfide bond improved protein trans-splicing increases plasma coagulation activity in C57BL/6 mice following portal vein FVIII gene delivery by dual vectors.  

PubMed

Protein trans-splicing based dual-vector factor VIII (FVIII) gene delivery is adversely affected by less efficiency of protein splicing. We sought to increase the amount of spliced FVIII protein and plasma coagulation activity in dual-vector FVIII transgene in mice by means of strengthening the interaction of inteins, protein splicing elements, thereby facilitating protein trans-splicing. Dual-vector delivery of the FVIII gene in cultured cells showed that replacement of Met226 in the heavy chain and Asp1828 in the light chain with Cys residues could facilitate inter-chain disulfide linking and improve protein trans-splicing, increasing the levels of spliced FVIII protein. In this study, C57BL/6 mice were coadministered dual vectors of intein-fused human FVIII heavy chain and light chain with Cys mutations via portal vein injection into the liver. Forty-eight hours post-injection, plasma was collected and analyzed for FVIII antigen concentration and coagulation activity. These mice showed increased circulating FVIII heavy chain polypeptide (442 ± 151 ng m(L-1) vs. 305 ± 103 ng mL(-1)) and coagulation activity (1.46 ± 0.37 IU m(-1) vs. 0.85 ± 0.23 IU mL(-1)) compared with control mice co-administered dual vectors expressing the heavy and light chains of wild-type FVIII. Moreover, coagulation activity was similar to that of mice receiving a single vector expressing FVIII (1.79 ± 0.59 IU mL(-1)). These findings indicate that improving protein trans-splicing by inter-chain disulfide bonding is a promising approach for increasing the efficacy of dual-vector based FVIII gene transfer. PMID:23526393

Zhu, Fuxiang; Liu, Zelong; Wang, Xiaolei; Miao, Jing; Qu, Huige; Chi, Xiaoyan

2013-03-23

314

Explosion from argon cautery during proctoileoscopy of a patient with a colectomy.  

PubMed

We report a unique case of a 70-year-old woman with Gardner's syndrome who had a subtotal colectomy with ileoproctostomy. Since then, she has undergone 12 uncomplicated proctoileoscopies, each time with argon plasma coagulation ablation of small polyps without any bowel preparation. However, during the most recent procedure, when we attempted to cauterize some rectal polyps, an immediate explosion occurred, leading to multiple rectal and ileal perforations that required surgical repair with a temporary end ileostomy. This event suggests that bacterial fermentation of colonic content or visible feces is not necessary for combustion because we observed a cautery-related explosion in the absence of a colon. This case shows the need for adequate bowel preparation if cautery is to be used, even in patients who have undergone a colectomy. PMID:22728385

Lin, Otto S; Biehl, Thomas; Jiranek, Geoffrey C; Kozarek, Richard A

2012-06-19

315

The Solar Argon Abundance  

Microsoft Academic Search

The solar argon abundance cannot be directly derived by spectroscopic observations of the solar photosphere. The solar argon abundance is evaluated from solar wind measurements, nucleosynthetic arguments, observations of B stars, H II regions, planetary nebulae, and noble gas abundances measured in Jupiter's atmosphere. These data lead to a recommended argon abundance of N(Ar)=91,200+\\/-23,700 (on a scale where Si=106 atoms).

Katharina Lodders

2008-01-01

316

Potassium-argon dating  

Microsoft Academic Search

First results in an extensive programme in potassium-argon dating at Berkeley arc reported. Ultra-high-vacuum techniques have been incorporated in the argon extraction apparatus and in a new mass spectrometer especially designed for these researches. It is found that, because of these improvements, the radiogenic argon in small and young samples can be measured with precision. Analytical data for a group

R. E. Folinsbee; J. Lipson; J. H. Reynolds

1956-01-01

317

Investigation of the Dependence of Argon Metastable State Population on the Conditions of High-Frequency Glow Discharge Excitation  

NASA Astrophysics Data System (ADS)

The population of metastable states of argon atoms in high-frequency glow discharge plasma is calculated. Dependences of the population of metastable states of argon atoms in the high-frequency glow discharge plasma on the standard gas flow rate (14-30 sccm) and vibration generator power (10-50 W) in the atmospheres of pure argon and argon-silane (95% Ar + 5% SiH4) mixture are investigated together with the dependence of the population of metastable states of argon atoms in the high-frequency glow discharge plasma on the silane content (0.5-5%) in the argon-silane mixture.

Baisova, B. T.; Demin, A. S.; Pushkarev, A. A.; Strunin, V. I.; Khudaibergenov, G. Zh.

2013-06-01

318

A sample introduction system for an inductively coupled plasma operating on an argon carrier gas flow of 0.1 l/min  

NASA Astrophysics Data System (ADS)

A sample introduction system is described for use with a water-cooled ICP torch described previously [ Anal. Chem.51, 2378 (1979)]. It consists of a narrow bore (100 ?m) stainless steel Babington nebulizer operating on 0.05 to 0.2 l/min argon inserted into a small (10 ml) nebulizer chamber. The solvent is force-fed continuously by gas pressure or with a peristaltic pump. Liquid samples can be supplied continuously or in discrete quantities using a sample loop between the pump and the nebulizer. In the latter case only 25 s are required for sample change. The nebulization efficiency for water and organic solvents is comparable to that of conventional pneumatic nebulizers operating on 1 l/min argon.

Ripson, P. A. M.; de Galan, L.

319

Argon endolaser suture lysis  

NASA Astrophysics Data System (ADS)

Purpose: To develop a simple suture lysis technique for post-trabeculectomy examinations under anesthesia since slit lamp laser suture lysis in the clinic cannot be performed on infants and young children. Methods: An argon endolaser probe lysed 10-0 nylon suture through conjunctiva harvested from human cadaver eyes. Since suture lysis failed with the thick Hoskins lens, clear plastic from the suture package compressed the conjunctiva. The conjunctiva was examined histologically. Results: Argon laser suture lysis (250 mW, 0.1 sec, 488 - 514 nm) was achieved without conjunctival damage. Conclusion: The argon endolaser probe is effective for suture lysis when the slit lamp cannot be used.

Cameron, Bruce D.; Joos, Karen M.; Shen, Jin-Hui

1996-05-01

320

Proteases, Coagulation, and Inflammation  

Microsoft Academic Search

\\u000a It is now widely accepted that inflammation and coagulation are two intimately linked processes. Pre-clinical evidence on\\u000a this cross-talk have accumulated since 1961 when it was demonstrated that coagulation factors could cause an inflammatory\\u000a response in in vivo pre-clinical studies. The discovery of thrombin receptors has been instrumental in clarifying several\\u000a molecular aspects at the basis of the cross-talk between

Giuseppe Cirino; Mariarosaria Bucci

321

Application of Conventional and Low-Flow Torches for the Analysis of Xylene and Tetralin-Based Petroliferous Materials by Argon and Oxygen-Argon ICP-AES  

Microsoft Academic Search

The merits of xylene and tetralin as diluents are compared for the analysis of petroliferous materials, using argon and argon-oxygen ICPs and conventional demountable and low-flow torches. The use of a mixed argon-oxygen plasma eliminated the formation of carbon particles in the torches. However, background was higher and signal-to-background ratios were generally lower in the oxygen-doped plasma. With tetralin the

I. B. Brenner; E. Dorfman

1995-01-01

322

[Pitfall in coagulation tests].  

PubMed

Coagulation assays are prone to pre-analytical problems and results may be influenced by varying clinical and pharmaceutical aspects. Particularly anticoagulants interact with coagulation testing in many ways. Thromboplastin time will be prolonged dose-dependently in patients taking vitamin K antagonists; moreover the new oral anticoagulants have been shown to have variable impact on the results of the thromboplastin time as well as on other coagulation tests, depending on the mechanism of action of these new drugs as well as on the mechanism of the coagulation test. When measuring anti-Xa activity it should be realised that all drugs with anti-Xa activity will influence the result, which means not only heparins but also the new anti-Xa inhibitors. Respective calibration curves are an indispensable condition to provide the clinician with valuable results. On the other hand this implies that the laboratory knows which anticoagulant is given to the patient. This is an example among others that clinical aspects are important to know for proper interpretation of the results of coagulation testing. Other examples are e. g. bleeding disorders, actual bleeding status or thromboembolic events. Several cases are discussed which exemplify possible pitfalls in the interpretation of coagulation testing. PMID:23876750

Gähler, Anita; Wuillemin, Walter A

2013-08-01

323

Hard tissue response to argon plasma cleaning/sterilisation of customised titanium abutments versus 5-second steam cleaning: results of a 2-year post-loading follow-up from an explanatory randomised controlled trial in periodontally healthy patients.  

PubMed

Purpose: The aim of this triple-blinded randomised controlled trial was to test if argon plasma cleaning/ sterilisation of customised abutments can affect peri-implant marginal bone levels when compared to 5 seconds of steam cleaning. Materials and methods: A total of 20 consecutive periodontally healthy patients requiring single implant-supported restorations in the maxillary premolar or anterior area were selected. All patients received a single implant. At abutment connection, customised abutments were randomly allocated to control (subjected only to usually adopted steam cleaning, CG) and test groups (subjected to plasma cleaning/sterilisation, TG). Abutments were screwed in at 32 Ncm, provisional restorations adapted and periapical radiographs were taken using customised film holders. Two weeks later, definitive restorations were placed. Patients were followed-up for 2 years post-loading. Outcome measures were implant/crown success, complications, periapical marginal bone level changes on periapical standardised radiographs, and microbiological analyses of the abutments after customisation and cleaning procedures but before connection. Comparisons between groups were performed by independent sample t tests (significance threshold of P ? 0.05). Results: No patient dropped out 2 years after loading. The presence of bacterial growth (staphylococci, including Staphylococcus aureus) was observed only on the CG abutments. No implant failed and no complications occurred. After 2 years of prosthetic loading, radiographic analysis revealed a statistically significantly higher mean bone loss for the CG group (mean difference 0.4 mm; 95% CI 0.08-0.73; P = 0.018). Conclusions: This study suggests that removal of contaminants from titanium abutments using plasma of argon can allow for better bone level maintenance when compared to 5-second steam cleaning of titanium abutments. It is therefore important to use cleaned and sterilised customised abutments in patients. PMID:24179979

Canullo, Luigi; Penarrocha, David; Micarelli, Costanza; Massidda, Orietta; Bazzoli, Mauro

2013-01-01

324

Coagulation Changes during Presyncope and Recovery  

PubMed Central

Orthostatic stress activates the coagulation system. The extent of coagulation activation with full orthostatic load leading to presyncope is unknown. We examined in 7 healthy males whether presyncope, using a combination of head up tilt (HUT) and lower body negative pressure (LBNP), leads to coagulation changes as well as in the return to baseline during recovery. Coagulation responses (whole blood thrombelastometry, whole blood platelet aggregation, endogenous thrombin potential, markers of endothelial activation and thrombin generation), blood cell counts and plasma mass density (for volume changes) were measured before, during, and 20 min after the orthostatic stress. Maximum orthostatic load led to a 25% plasma volume loss. Blood cell counts, prothrombin levels, thrombin peak, endogenous thrombin potential, and tissue factor pathway inhibitor levels increased during the protocol, commensurable with hemoconcentration. The markers of endothelial activation (tissue factor, tissue plasminogen activator), and thrombin generation (F1+2, prothrombin fragments 1 and 2, and TAT, thrombin-antithrombin complex) increased to an extent far beyond the hemoconcentration effect. During recovery, the markers of endothelial activation returned to initial supine values, but F1+2 and TAT remained elevated, suggestive of increased coagulability. Our findings of increased coagulability at 20 min of recovery from presyncope may have greater clinical significance than short-term procoagulant changes observed during standing. While our experiments were conducted in healthy subjects, the observed hypercoagulability during graded orthostatic challenge, at presyncope and in recovery may be an important risk factor particularly for patients already at high risk for thromboembolic events (e.g. those with coronary heart disease, atherosclerosis or hypertensives).

Cvirn, Gerhard; Schlagenhauf, Axel; Leschnik, Bettina; Koestenberger, Martin; Roessler, Andreas; Jantscher, Andreas; Vrecko, Karoline; Juergens, Guenther; Hinghofer-Szalkay, Helmut; Goswami, Nandu

2012-01-01

325

Effects of lower doses of conjugated equine estrogens and medroxyprogesterone acetate on plasma lipids and lipoproteins, coagulation factors, and carbohydrate metabolism  

Microsoft Academic Search

Objective: To determine the effects of lower doses of conjugated equine estrogens (CEE) alone or CEE and medroxyprogesterone acetate (MPA) on lipoproteins, carbohydrate metabolism, and coagulation\\/fibrinolytic factors.Design: Randomized, double-blind, placebo-controlled study.Setting: Multicenter substudy of the Women’s HOPE trial.Patient(s): Seven hundred and forty-nine healthy, postmenopausal women.Intervention(s): Women were randomized to receive the following doses in milligrams per day: 0.625 CEE; 0.625

Rogerio A Lobo; Trudy Bush; Bruce R Carr; James H Pickar

2001-01-01

326

Depleted Argon from Underground Sources  

NASA Astrophysics Data System (ADS)

Argon is a strong scintillator and an ideal target for Dark Matter detection; however 39Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in 39Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO2 well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO2. We first concentrate the argon locally to 3% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation, and then the N2 and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO2 facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

Back, H. O.; Alexander, T.; Alton, A.; Galbiati, C.; Goretti, A.; Kendziora, C.; Loer, B.; Montanari, D.; Mosteiro, P.; Pordes, S.; Rogers, H.

2011-04-01

327

Depleted Argon from Underground Sources  

SciTech Connect

Argon is a strong scintillator and an ideal target for Dark Matter detection; however {sup 39}Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in {sup 39}Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO{sub 2} well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO{sub 2}. We first concentrate the argon locally to 3% in an Ar, N{sub 2}, and He mixture, from the CO{sub 2} through chromatographic gas separation, and then the N{sub 2} and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO{sub 2} facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

Back, H. O.; Galbiati, C.; Goretti, A.; Loer, B.; Montanari, D.; Mosteiro, P. [Department of Physics, Princeton University, Jadwin Hall, Princeton, NJ 08544 (United States); Alexander, T.; Alton, A.; Rogers, H. [Augustana College, Physics Department, 2001 South Summit Ave., Sioux Fall, SD 57197 (United States); Kendziora, C.; Pordes, S. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)

2011-04-27

328

Characterization of the coagulation system in healthy dolphins: the coagulation factors, natural anticoagulants, and fibrinolytic products  

Microsoft Academic Search

In dolphins, blood pooling and acidosis from lack of oxygenation with prolonged underwater stay are not associated with intravascular clotting as it would be in terrestrial mammals, while shed blood clots promptly, and intravascular clots form after death. This intriguing physiologic adaptation prompted further investigation of the coagulation system in the dolphin. We studied the plasma from 17 dolphins (Tursiops

Rita F. Tibbs; M. Tarek Elghetany; Lethu T. Tran; W. Van Bonn; T. Romano; Daniel F. Cowan

2005-01-01

329

The Solar Argon Abundance  

NASA Astrophysics Data System (ADS)

The solar argon abundance cannot be directly derived by spectroscopic observations of the solar photosphere. The solar argon abundance is evaluated from solar wind measurements, nucleosynthetic arguments, observations of B stars, H II regions, planetary nebulae, and noble gas abundances measured in Jupiter's atmosphere. These data lead to a recommended argon abundance of N(Ar)=91,200+/-23,700 (on a scale where Si=106 atoms). The recommended abundance for the solar photosphere [on a scale where logN(H)=12] is A(Ar)photo=6.50+/-0.10, and taking element settling into account, the solar system (protosolar) abundance is A(Ar)solsys=6.57+/-0.10.

Lodders, Katharina

2008-02-01

330

Coagulants modulate the hypocholesterolemic effect of tofu (coagulated soymilk)  

Microsoft Academic Search

The recent increase in soymilk and tofu (coagulated soymilk) consumption especially in western countries is due to the recognition of the health benefits of soy foods. The amount and the type of coagulated biomolecules (such as isoflavones) vary with the type of coagulant, and this will inevitable alter their biological activity. This study sought to assess the effect of some

Ganiyu Oboh

331

SLD liquid argon calorimeter  

SciTech Connect

The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z[sup 0] decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z[sup 0] events) is discussed.

Vella, E.

1992-10-01

332

SLD liquid argon calorimeter  

SciTech Connect

The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z{sup 0} decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z{sup 0} events) is discussed.

Vella, E.; SLD Collaboration

1992-10-01

333

Viscoelastic Properties of Coagulating Milk  

Microsoft Academic Search

The viscoelastic properties of co- agulating renneted milk were studied by a dynamic testing technique. With this technique we obtained the dynamic viscosity and elasticity of the milk gel without affecting the coagulation process. We give results in absolute units for the coagulation process as a function of coagulation temperature, rennet con- centration, and concentration of calcium chloride. The shear

Leif Bohlin; Per-Olof Hegg; Helena Ljusberg-Wahren

1984-01-01

334

COAGULATION IN EMBRYONIC BLOOD.  

PubMed

1. In pig embryos of 100 to 270 mm. the average coagulation time of the blood was found to be about 23 minutes. This represents a coagulation time six to eight times greater than that obtained for the adult. 2. The first evidence of coagulation in the blood of these embryos consisted in the appearance of small masses of fibrin deposited almost invariably at the side of the test-tube. The ensuing coagulum was, as a rule, in the nature of a sliding clot, never attaining any marked degree of density or firmness. 3. In an analysis of the possible factors involved in this greater coagulation time of embryonic blood, it was found that numerically the blood platelets varied from 415,000 to 800,000 per c.mm., a content not differing in any significant degree from that of the adult, in which the average was found to be about 588,000 with a variation from 544,000 to 932,000. 4. The addition of platelet material obtained from adult pig blood reduced the coagulation time for embryonic blood to an average of 8.4 minutes, a decrease of 75 per cent. 5. The addition of two drops of 0.5 per cent calcium chloride reduced the coagulation time for embryonic blood to an average of 10.3 minutes, a reduction of over 50 per cent. 6. The addition of tissue extract to embryonic blood reduced the coagulation time to an average of 3.7 minutes, a time essentially equivalent to that obtained for adult blood. The clot was of a much firmer character than that obtained either in the normal coagulation or in the calcium experiments. 7. Chemical analysis demonstrated a calcium content in embryonic blood in excess of that of the adult, in the proportion of 7 : 5. 8. In view of the results indicated above, it became evident that the calcium in embryonic blood must be present in some combined form. This conclusion is supported by experiments in which barium and magnesium brought about a reduction in coagulation time in non-oxalated embryonic blood, but did not have this effect when added to oxalated blood, indicating in the former case, on the basis of the specificity of calcium, a liberation of free calcium ions. With oxalated blood, it was also found that under certain conditions coagulation could be brought about by the addition of tissue extract. 9. That the fibrinogen content plays no important part in coagulation time is shown by the fact that whereas the maximum amount of fibrin obtained by defibrinating embryonic blood was about 12 per cent of that obtained from the adult, nevertheless upon the addition of tissue extract the coagulation time of embryonic blood becomes equivalent to that of the adult. 10. The presence of bile was demonstrated in the circulating blood of these embryos. Since it was further demonstrated that by the addition of bile to adult blood conditions could be produced essentially identical with those of embryonic blood, and since in the preceding analysis of the factors involved in coagulation no significant differences could be demonstrated between the blood of the embryos and that of the adult other than the presence of bile in the former, the data justify the conclusion that the bile content in the circulation of 100 to 270 mm. pig embryos constitutes the primary factor accounting for the greater coagulation time in the blood of these embryos. A condition in embryonic blood in some respects comparable with that of icterus is also indicated. 11. In the calcium experiments the results are apparently due primarily to the introduction of calcium ions in excess of the amount which enters into chemical combination with the bile present. With tissue extract it appears that the free calcium ions essential for the initiation of coagulation must be liberated through some interaction with the constituents of bile. 12. The results of this study suggest that the normal coagulation of embryonic blood, as far as bile is concerned, involves a process comparable with that obtained after the addition of tissue extract or cephalin, but on a smaller scale. In the embryonic blood in vitro, through the gradual disintegration of cellular elements, a

Emmel, V E; Levinson, S A; Fisch, M E

1920-01-31

335

Phospholipase A 2-induced coagulation abnormalities after bee sting  

Microsoft Academic Search

We will examine the correlation between various bee venom phospholipase A2 (PLA2) concentrations and several parameters of coagulation in human plasma in order to offer a rationale for requesting a particular laboratory coagulation test after bee sting(s). We will also evaluate in vitro the influence of clinically available drugs with a noncompetitive inhibitory effect on PLA2 on the anticoagulant effect

Georg Petroianu; Jie Liu; Ursula Helfrich; Wolfgang Maleck; Roderich Rüfer

2000-01-01

336

Excimer Emission from Argon Microhollow Cathode Discharges  

NASA Astrophysics Data System (ADS)

Excimer emission from direct current microhollow cathode discharges had been studied for rare gases and mixtures of rare gases and halides as working gases [1]. In static xenon, the dc efficiency was measured as 6%-9%. In static argon, however, the efficiency is only on the order of 1%. This relatively low value was found to be due to excimer quenching processes caused by impurities. By flowing the argon, rather than operating under static conditions we could increase the efficiency to 6%. Applying a 10 ns pulse of 600 V to the DC discharge in argon resulted in an increased intensity by a factor of six. The decay time for argon excimer emission was found to be 500 ns, indicating that quenching processes even with purging of the discharge chamber are still more effective by a factor of six in depopulating the excimer level than excimer radiation. The major quenching effect is based on resonant energy transfer from the argon excimer to atomic oxygen [2]. The addition of small amounts of oxygen allowed us therefore to convert the argon excimer emission centered at 128 nm into narrowband emission at 130.4 nm (oxygen triplet) with an optical power of up to 13 mW.This material was supported by NSF (CTS-0078618).[1] Karl H. Schoenbach, Ahmed El-Habachi, Mohamed M. Moselhy, Wenhui Shi, and Robert H. Stark, Physics of Plasmas 7, 2186 (2000). [2] M. Moselhy, R.H. Stark, K.H. Schoenbach, and U. Kogelschatz, Appl. Phys. Lett. 78, 880 (2001).

Moselhy, Mohamed; Schoenbach, Karl H.

2002-10-01

337

Argon laser for otosclerosis  

NASA Astrophysics Data System (ADS)

Up to now, among different kinds of lasers an argon laser is mostly used for otosclerosis. Exposure conditions at use of the laser beam are still not well defined. In order to achieve the optimum conditions a series of experiments has been made. Obtained results are presented in this paper.

Michalski, Wojciech; Pospiech, Lucyna; Jankowska-Kuc, Malgorzata

1995-03-01

338

Cloning and expression of rat coagulation factor VII  

Microsoft Academic Search

Smaller and widely available animals such as rats are commonly used to evaluate antithrombotic drug candidates in vivo. However, the isolation and purification of FVII from rats and other species is very challenging because they are present in extremely low levels in plasma (?10 nM). Furthermore, purification of FVII from other coagulation factors present in the plasma such as prothrombin,

Shobha Seetharam; Kathleen Murphy; Charity Atkins; Giora Feuerstein

2003-01-01

339

Darexaban: anticoagulant effects in mice and human plasma in vitro, antithrombotic effects in thrombosis and bleeding models in mice and effects of anti-inhibitor coagulant complex and recombinant factor VIIa.  

PubMed

Here, we investigated the anticoagulant effects of darexaban in mice and human plasma in vitro, effects of darexaban in thrombosis and bleeding models in mice, and reversal effects of anti-inhibitor coagulant complex (ACC) and recombinant factor VIIa (rFVIIa) on anticoagulant effects of darexaban. In mice, darexaban inhibited FXa activity in plasma with an ED50 value of 24.8 mg/kg. Both darexaban and warfarin prolonged prothrombin time (PT) at 3 mg/kg and 0.3 mg/kg/day, respectively. PT and activated partial thromboplastin time (aPTT) prolonged by darexaban were dose-dependently reversed by intravenously-administered rFVIIa, significantly so at 1 mg/kg. In a pulmonary thromboembolism (PE) mouse model, both darexaban and warfarin dose-dependently reduced the mortality rate, significantly so at 10 mg/kg and 3 mg/kg/day, respectively. In a FeCl3-induced venous thrombosis (VT) mouse model, darexaban (0.3-10 mg/kg) dose-dependently decreased the thrombus protein content, significantly so at doses of 3 mg/kg or higher. In a tail-transection mouse model, darexaban had no significant effect on the amount of blood loss at doses up to 10 mg/kg, while warfarin showed a dose-dependent increase in blood loss, significantly so from 1 mg/kg/day. Darexaban and its metabolite darexaban glucuronide significantly prolonged PT and aPTT in human plasma in vitro, and while rFVIIa concentration-dependently reversed the prolonged PT in this plasma, ACC dose-dependently reversed both PT and aPTT changes prolonged by darexaban. Taken together, these results suggest that darexaban has a potential to be an oral anticoagulant with a better safety profile than warfarin, and that rFVIIa and ACC may be useful as antidotes to darexaban in cases of overdose. PMID:23591155

Kaku, Seiji; Suzuki, Mami; Saitoh, Minori; Funatsu, Toshiyuki; Uemura, Toshio; Suzuki, Ken-ichi; Iwatsuki, Yoshiyuki; Kawasaki, Tomihisa

2013-04-13

340

Comparative 2D Radiation MHD Simulations of Argon Gas Puff Z-pinch Plasma Experiments on the Sandia Z Machine Using the Radiative Diffusion and CRE Transport Models  

Microsoft Academic Search

The recent development of the computationally efficient tabulated collisional radiative equilibrium (TCRE) radiation transport model(J.W. Thornhill, J.P. Apruzese, J. Davis, R.W. Clark, A.L. Velikovich, J.L. Giuliani, Jr., Y.K. Chong, K.G. Whitney, C. Deeney, C.A. Coverdale and F.L. Cochran, Phys. Plasmas 7, 3480 (2001).) has made possible full multidimensional radiation MHD simulations of hot dense Z-pinch plasmas with a realistic description

Y. K. Chong; J. W. Thornhill Giuliani Jr.; J. P. Apruzese; R. E. Terry; J. Davis

2001-01-01

341

Argon frost continuous cryopump for fusion applications  

SciTech Connect

A cryopumping system based on the snail continuous cryopump concept is being developed for fusion applications under a DOE SBIR grant. The primary pump is a liquid helium cooled compound pump designed to continuously pump and fractionate deuterium/tritium and helium. The D/T pumping stage is a 500 mm bore cryocondensation pump with a nominal pumping speed of 45,000 L/s. It will be continuously regenerated by a snail regeneration by head every 12 minutes. Continuous regeneration will dramatically reduce the vulnerable tritium inventory in a fusion reactor. Operating at an inlet pressure of 1 millitorr, eight of these pumps could pump the projected D/T flow in the ITER CDA design while reducing the inventory of tritium in the pumping system from 630 to 43 grams. The helium fraction will be pumped in a compound argon frost stage. This stage will also operate continuously with a snail regeneration head. In addition the argon spray head will be enclosed inside the snail, thereby removing gaseous argon from the process chamber. Since the cryocondensation stage will intercept over 90% of the D/T/H steam, a purified stream from this stage could be directly reinjected into the plasma as gas or pellets, thereby bypassing the isotope separation system and further simplifying the fuel cycle. Experiments were undertaken in Phase I which demonstrated continuous cryosorption pumping of hydrogen on CO{sub 2} and argon frosts. The pumping system and its relevance to fusion reactor pumping will be discussed.

Foster, C.A.; McCurdy, H.C.

1993-12-01

342

Asthma and coagulation.  

PubMed

Asthma is a chronic airway disease characterized by paroxysmal airflow obstruction evoked by irritative stimuli on a background of allergic lung inflammation. Currently, there is no cure for asthma, only symptomatic treatment. In recent years, our understanding of the involvement of coagulation and anticoagulant pathways, the fibrinolytic system, and platelets in the pathophysiology of asthma has increased considerably. Asthma is associated with a procoagulant state in the bronchoalveolar space, further aggravated by impaired local activities of the anticoagulant protein C system and fibrinolysis. Protease-activated receptors have been implicated as the molecular link between coagulation and allergic inflammation in asthma. This review summarizes current knowledge of the impact of the disturbed hemostatic balance in the lungs on asthma severity and manifestations and identifies new possible targets for asthma treatment. PMID:22262775

de Boer, J Daan; Majoor, Christof J; van 't Veer, Cornelis; Bel, Elisabeth H D; van der Poll, Tom

2012-01-18

343

Isentropic Compression of Argon  

SciTech Connect

We are studying the transition of argon from an insulator to a conductor by compressing the frozen gas isentropically to pressures at which neighboring atomic orbitals overlap sufficiently to allow some electron motion between atoms. Argon and the other rare gases have closed electron shells and therefore remain montomic, even when they solidify. Their simple structure makes it likely that any measured change in conductivity is due to changes in the atomic structure, not in molecular configuration. As the crystal is compressed the band gap closes, allowing increased conductivity. We have begun research to determine the conductivity at high pressures, and it is our intention to determine the compression at which the crystal becomes a metal.

H. Oona; J.C. Solem; L.R. Veeser, C.A. Ekdahl; P.J. Rodriquez; S.M. Younger; W. Lewis; W.D. Turley

1997-08-01

344

Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol  

SciTech Connect

Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure {alpha}-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)

2007-06-15

345

Evaluation of coagulation kinetics using thromboelastometry—methodologic influence of activator and test medium  

Microsoft Academic Search

Renewed interest has arisen in the use of thromboelastography\\/thromboelastometry in evaluating coagulation kinetics. The test\\u000a medium, type of activator, and its concentration may influence the interpretation of coagulation kinetics. This study aimed\\u000a to investigate methodologic influences of activator and test medium on thromboelastometric parameters of coagulation kinetics.\\u000a Dynamic clot formation was evaluated by thromboelastometry using whole blood (WB), platelet-rich plasma,

Benny Sørensen; Christian Fenger-Eriksen; Kirsten Christiansen; Ole H. Larsen; Jørgen Ingerslev

2010-01-01

346

Argon Purification Reference and Recommendation  

SciTech Connect

This engineering note is a reference for future consideration on the purification of argon. The original concern was for the possibility of argon contamination from components in the cryostats over long-term storage. An argon purification system could also be useful for purifying the contents of the argon dewar. The general conclusion is that most of the systems researched are too expensive at this time, but the recommended choice would be Centorr Furnaces. There were three basic types of purification systems which were to be considered. The first was the molecular sieve. This method would have been the preferred one, because it was claimed that it could purify liquid argon, removing liquid oxygen from the argon. However, none of the commercial companies researched provided this type of purification for use with liquid argon. Most companies said that this type of purification was impossible, and tests at IB-4 confirmed this. The second system contained a copper oxide to remove gaseous oxygen from argon gas. The disadvantage of this system wass that the argon had to be heated to a gas, and then cooled back down to liquid. The third system was similar to the second, except that it used tungsten or another material like titanium. This system also needed to heat the argon to gas, however the advantage of this system was that it supposedly removed all contaminants, that is, everything except for inert gases. Of the three systems, the third is the type manufactured by Centorr Furnaces, which uses a titanium charge.

Wu, J.; /Fermilab

1991-05-23

347

Numerical Simulation of Electron Transport in Electric and Magnetic Fields for Analysis of Electron Temperature and Number Density Profiles Measured in Argon Magnetic Neutral Loop Discharge Plasma  

Microsoft Academic Search

A Monte Carlo simulation of electron transport in electric and magnetic fields was performed to analyze experimental data of the electron temperature Te and electron number density ne measured in a magnetic neutral loop discharge (NLD) plasma driven in Ar at 0.13 Pa. Te and ne in the vicinity of the substrate holder were measured with a triple probe, and

Hirotake Sugawara; Tsuyoshi Osaga; Hideo Tsuboi; Kiyoshi Kuwahara; Seiji Ogata

2010-01-01

348

A model for plasma formation in a reflective axicon and tube for a proposed Ne-like argon laser at 46.9 nm  

Microsoft Academic Search

We have sought ways to improve the coupling of the pump laser energy to a low density plasma suitable for collisional XUV lasing. At very high intensity, laser light can be coupled directly to a low density gas through multiphoton ionization. At the intensities of our pump, the radiation must be absorbed by inverse bremsstrahlung, which is inefficient at low

S. K. Chatterji; M. Fleury; M. H. Muendel; W. Hodge; P. L. Hagelstein

1996-01-01

349

Effects of RF power on plasma phase reactions and film structure in deposition of a-C:H by styrene/argon discharge  

SciTech Connect

In ion-assisted plasma enhanced chemical vapor depositions (PECVD), the applied RF power affects both plasma phase reactions and deposited film structure. These dual effects are investigated in PECVD of a-C:H films by using styrene and Ar mixture. The films are deposited in a 13.56 MHz, RF driven asymmetric plasma reactor at 25 C. In situ impedance analysis is used to estimate the ion energy and flux at the substrate, while an on-line mass spectrometer (MS) is used to analyze the plasma chemistry, and film structure is characterized by Fourier transform infrared (FTIR) spectroscopy and ellipsometry. The impedance analysis shows that both ion energy and ion flux increase with increasing RF power. The MS data show that the RF power has the major effect on the degree of dissociation of styrene. The FTIR spectra of the deposited films indicate that CH{sub 3} is likely to be the precursor for the diamond-like carbon deposition. The ion energy flux (IEF) is shown to have a significant effect on the film structure. With increasing IEF, films show decreases in hydrogen concentration, increases in sp{sup 2} carbon fraction, and increases in refractive indexes.

Lee, J.H.; Kim, D.S.; Lee, Y.H.; Farouk, B. [Drexel Univ., Philadelphia, PA (United States)

1996-04-01

350

[Aqueous humor outflow capacity after argon laser trabeculoplasty. Preliminary report].  

PubMed

In a prospective study of 44 eyes with open angle-glaucoma and 27 with pseudocapsular glaucoma, the aqueous humor outflow facility was controlled for up to 12 months following argon laser trabeculoplasty (ALT). The average increase in the facility of outflow, which was 70% in open-angle glaucoma, was 25% higher in pseudocapsular glaucoma. In successful ALT, this increase in outflow facility was established within the first 20 hours after coagulation and did not decrease during the following year. There were no major complications such as transitory elevations of intraocular pressure, hyphema, or severe uveitis; this fact is interpreted as a result of the authors' technique, in which only the light-pigmented trabecular meshwork is coagulated. PMID:4039773

Merté, H J; von Denffer, H; Hirsch, B

1985-03-01

351

Coagulation Abnormalities in Critical Illness  

Microsoft Academic Search

\\u000a In critically ill patients coagulation abnormalities often occur. The most pronounced manifestation of these, caused by overwhelming\\u000a activation of the coagulation system, is disseminated intravascular coagulation (DIC) which is also considered to be a component\\u000a of the multiple organ dysfunction syndrome (MODS). There is no generally accepted definition of DIC but recently a working\\u000a definition has been proposed [1]: “DIC

L. G. Thijs

352

Parametric Studies of Argon Glow Discharges  

NASA Astrophysics Data System (ADS)

The basis of this work is one-dimensional fluid model of electrical properties of a argon glow discharge with planar electrods. The results from this model are the spatial profiles of electric field, the charged particle densities, and ionization source term. The range of current densities considered is between 0.1 and 0.6 mA/cm2. To calculate the gas temperature, we solve the one dimensional heat transport equation. The gas temperature profile is reintroduced into the electrical model. In the fluid model, the electrons and ions are described by their continuity and momentum transfer equations in the drift diffusion approximation, and these equations are solved together with Poissons equation for the electric field. Key words : Plasma, Lamp, Argon, Power, Energy deposition, Modeling, Heating

Ahmed, Belasri; Khelifa, Yanallah

2003-10-01

353

Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon\\/nitrogen  

Microsoft Academic Search

In this letter, atmospheric-pressure glow discharges in gamma mode with argon\\/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the alpha-gamma coexisting mode or gamma mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen,

Hua-Bo Wang; Wen-Ting Sun; He-Ping Li; Cheng-Yu Bao; Xing Gao; Hui-Ying Luo

2006-01-01

354

Effect of ion energy fluence on the topography and wettability of low-density polyethylene exposed to inductively coupled argon plasma  

Microsoft Academic Search

The topography and wettability of low-density polyethylene (LDPE) were modified by an inductively coupled Ar plasma. The extent and mechanisms of surface modification were correlated with the ion energy fluence, determined from the ion density measured with a Langmuir probe. The ion energy fluence was varied in the range of (0.3-6.3) × 105 J m-2 by changing the sample distance

S. Tajima; K. Komvopoulos

2006-01-01

355

Effects of argon and oxygen flow rate on water vapor barrier properties of silicon oxide coatings deposited on polyethylene terephthalate by plasma enhanced chemical vapor deposition  

Microsoft Academic Search

Plasma polymer coatings were deposited from hexamethyldisiloxane on polyethylene terephthalate (PET) substrates while varying the operating conditions, such as the Ar and O2 flow rates, at a fixed radio frequency power of 300W. The water vapor transmission rate (WVTR) of the untreated PET was 54.56g\\/m2\\/day and was decreased after depositing the silicon oxide (SiOx) coatings. The minimum WVTR, 0.47g\\/m2\\/day, was

Sung-Ryong Kim; Moinul Haque Choudhury; Won-Ho Kim; Gon-Ho Kim

2010-01-01

356

Polarizability of Singly Ionized Argon.  

National Technical Information Service (NTIS)

The polarizability (specific refractivity or Gladstone-Dale constant) of singly ionized argon was determined experimentally using dual-frequency laser interferometry over a significant wavelength range. (Author)

I. I. Glass M. P. F. Bristow

1972-01-01

357

Acquired coagulation disorders: revisited using global coagulation/anticoagulation testing.  

PubMed

Acquired coagulation defects are characterized by a decrease of both pro- and anti-coagulants. Because of this, we hypothesise that global tests, such as the prothrombin and partial thromboplastin times (PT and APTT), might be unsuitable for their investigation. Indeed, these tests are not good predictors of bleeding in acquired coagulopathies as they are in the congenital ones. This article discusses the possible reasons for this, using cirrhosis and the neonatal period as epitomes of acquired coagulation defects. Both display normal thrombin generation in the presence of thrombomodulin, in spite of prolonged PT and APTT. We surmise that, because of their design, the PT and APTT are responsive to thrombin generated as a function of pro-coagulants, but much less to thrombin inhibited by the anti-coagulants, especially protein C, which is activated to a limited extent in the absence of thrombomodulin. In conclusion, the PT and APTT can tell us whether or not a patient is deficient in one or more pro-coagulants, but not whether this deficiency is counterbalanced by a parallel deficiency of anti-coagulants. Thrombin generation assays are more suitable than PT and APTT for use in acquired coagulation defects. PMID:19659548

Tripodi, Armando; Chantarangkul, Veena; Mannucci, Pier M

2009-07-30

358

Isentropic compression of argon  

SciTech Connect

The compression was done in an MC-1 flux compression (explosive) generator, in order to study the transition from an insulator to a conductor. Since conductivity signals were observed in all the experiments (except when the probe is removed), both the Teflon and the argon are becoming conductive. The conductivity could not be determined (Teflon insulation properties unknown), but it could be bounded as being {sigma}=1/{rho}{le}8({Omega}cm){sub -1}, because when the Teflon breaks down, the dielectric constant is reduced. The Teflon insulator problem remains, and other ways to better insulate the probe or to measure the conductivity without a probe is being sought.

Veeser, L.R.; Ekdahl, C.A.; Oona, H. [and others

1997-06-01

359

Exercise Training-Induced Changes in Coagulation Factors in Older Adults  

Microsoft Academic Search

LOCKARD, M. M., R. GOPINATHANNAIR, C. M. PATON, D. A. PHARES, and J. M. HAGBERG. Exercise Training-Induced Changes in Coagulation Factors in Older Adults. Med. Sci. Sports Exerc., Vol. 39, No. 4, pp. 587-592, 2007. The coagulation cascade plays a critical role in the development of cardiovascular disease (CVD). Elevated plasma prothrombin fragment 1 + 2 (F1 + 2) and

MICHAEL M. LOCKARD; RAKESH GOPINATHANNAIR; CHAD M. PATON; DANA A. PHARES; JAMES M. HAGBERG

2007-01-01

360

Effect of interparticle forces on the coagulation of ultrafine SiO 2 particles  

Microsoft Academic Search

The mechanism of ultrafine (2 particle production under thermal arc plasma conditions is studied by modelling. Two cases of the process are considered in the model: (i) when it is determined as a pure free-molecular coagulation; (ii) when the coagulation is influenced by the interparticle forces. The Hamaker formula is used to present the van der Waals forces between the

E. Balabanova; D. Oliver

1996-01-01

361

Multivacancy excitations in Argon  

SciTech Connect

We have obtained high spectral resolution, low noise absorption spectra of argon at incident photon energies of 3.2 to 3.6 keV, just above the K-edge of argon. The measurements were made at the X-24A beam-line at the National Synchrotron Light Source at Brookhaven. This beam-line is equipped with a high resolution double crystal monochromator and silicon (111) was employed in these measurements. The measurements concentrate on two spectral regions: the double 1s31 vacancy at 20 to 40 eV above the K-edge of 3.20 keV; (Our improved resolution and signal-to-noise ratio helps in identifying several spectral series in this KM region); the 1s2p and 1s2s double vacancy regions at 250-400 eV above the edge. We will report our assignments to the structures, made utilizing the multiconfiguration Dirac-Fock GRASP code. Measurements in other rare gases are in progress.

Azuma, Y.; Berry, H.G.; Cowan, P.L. [Argonne National Lab., Chicago, IL (United States)] [and others

1993-05-01

362

Blood Coagulation, Inflammation and Malaria  

PubMed Central

I. ABSTRACT Malaria remains a highly prevalent disease in more than 90 countries and accounts for at least 1 million deaths every year. Plasmodium falciparum infection is often associated with a procoagulant tonus characterized by thrombocytopenia and activation of the coagulation cascade and fibrinolytic system; however, bleeding and hemorrhage are uncommon events, suggesting that a compensated state of blood coagulation activation occurs in malaria. This article i) reviews the literature related to blood coagulation and malaria in a historic perspective, ii) describes basic mechanisms of coagulation, anticoagulation, and fibrinolysis, iii) explains the laboratory changes in acute and compensated disseminated intravascular coagulation (DIC), iv) discusses the implications of tissue factor (TF) expression in the endothelium of P. falciparum-infected patients, and v) emphasizes the pro-coagulant role of parasitized erythrocytes (pRBC) and activated platelets in the pathogenesis of malaria. This article also presents the ‘Tissue Factor Model’ (TFM) for malaria pathogenesis, which places TF as the interface between sequestration, endothelial cell activation, blood coagulation disorder and inflammation often associated with the disease. The relevance of the coagulation-inflammation cycle for the multiorgan dysfunction and coma is discussed in the context of malaria pathogenesis.

Francischetti, Ivo M. B.; Seydel, Karl B.; Monteiro, Robson Q.

2010-01-01

363

Emission characteristics of mixed gas plasmas in low-pressure glow discharges  

Microsoft Academic Search

Glow discharge optical emission spectrometry (GD-OES) with mixed plasma gases is reviewed. The major topic is the effect of type and content of gases added to an argon plasma on the emission characteristics as well as the excitation processes. Emphasis is placed on argon–helium, argon–oxygen, and argon–nitrogen mixed gas plasmas. Results for non-argon-matrix plasmas, such as neon–helium and nitrogen–helium mixtures,

Kazuaki Wagatsuma

2001-01-01

364

Quantum well intermixing of multiple quantum wells on InP by argon plasma bombardment and the sputtered-SiO2 film  

NASA Astrophysics Data System (ADS)

A quantum well intermixing process combining inductively-coupled-plasma reactive ion etching (ICP-RIE) and SiO2 sputtering film was investigated for the InGaAsP and InGaAlAs multi-quantum wells (MQWs). Optimal distance is 300-nm-thick for InGaAsP and of 200-nm-thick for InGaAlAs. Between MQWs and the upper cladding by ICP-RIE and bombardment, covering the 300-nm-thick sputtered SiO2 using rapid thermal annealer (RTA) processing resulted in a band-gap blue-shift of 90 nm for InGaAsP and of 60 nm for InGaAlAs.

Chiu, C. L.; Lay, T. S.

2013-08-01

365

Brain neoplasms and coagulation.  

PubMed

Brain vasculature is uniquely programmed to protect central nervous system tissues and respond to their metabolic demands. These functions are subverted during the development of primary and metastatic brain tumors, resulting in vascular perturbations that are thought to contribute to progression and comorbidities of the underlying disease, including thrombosis and hemorrhage. Chronic activation of the coagulation system is particularly obvious in glioblastoma multiforme (GBM), where intratumoral vasoocclusive thrombosis may contribute to hypoxia, pseudopalisading necrosis, and angiogenesis. GBM is also associated with spontaneous or iatrogenic bleeding, and the emission of circulating procoagulants implicated in the unusually high risk of peripheral venous thromboembolism. Tissue factor (TF) expression is elevated in several types of brain tumors, including adult and pediatric GBM, as is the production of TF-containing microparticles (TF-MPs). Both TF expression and its vesicular emission are regulated by tumor microenvironment (e.g., hypoxia), in concert with activated oncogenic and growth factor pathways (RAS, EGFR, MET), as well as the loss of tumor suppressor gene activity (PTEN). Discovery of distinct oncogenic networks led to recognition of unique molecular subtypes within brain tumors, of which GBM (proneural, neural, classical, and mesenchymal), and medulloblastoma (SHH, WNT, group 3, and group 4) exhibit subtype-specific composition of the tumor coagulome. It remains to be established whether mechanisms of thrombosis and biological effects of coagulation in brain tumors are also subtype specific. In this regard, TF pathway represents a paradigm, and its impact on tumor dormancy, inflammation, angiogenesis, formation of cancer stem cell niches, and dissemination is a subject of considerable interest. However, establishing the extent to which TF and TF-MPs contribute to pathogenesis and thromboembolic disease in the context of primary and secondary brain tumors may require molecular stratification of patient populations. We suggest that a better understanding of these molecular linkages may pave the way to a more effective (targeted) therapy, prophylaxis, adjunctive use of anticoagulants, and other agents able to modulate interactions between brain tumors and the coagulation system. PMID:24108471

Magnus, Nathalie; D'Asti, Esterina; Garnier, Delphine; Meehan, Brian; Rak, Janusz

2013-10-09

366

Thermophoretically modified aerosol Brownian coagulation  

NASA Astrophysics Data System (ADS)

A theory of aerosol coagulation rates resulting from continuum-regime Brownian coagulation in the presence of size-dependent particle thermophoresis is developed and explored here. We are motivated by a wide variety of applications in which particle Brownian coagulation occurs in a nonisothermal gas where differential thermophoretic drift contributes to, but does not dominate, the encounter frequency between suspended spherical particles (e.g., mist droplets) of different sizes. We employ a Smoluchowski-like population-balance to demonstrate the relative roles of Brownian diffusion and thermophoresis in shaping the short and long time (asymptotic or “coagulation-aged”) mist-droplet size distribution (DSD) function. To carry out these combined-mechanism DSD-evolution calculations we developed a rational “coupled” coagulation rate constant (allowing for simultaneous Brownian diffusion and relative thermophoretic drift) rather than simply adding the relevant individual coagulation “kernels.” Dimensionless criteria are provided to facilitate precluding other coagulation mechanisms not considered here (such as simultaneous sedimentation or Marangoni-flow-induced mist-droplet phoresis) and potential complications not included in the present model [as finite-rate coalescence, initial departures from the continuum (Stokes drag-) limit, and even dense (nonideal) vapor effects].

Arias-Zugasti, Manuel; Rosner, Daniel E.

2011-08-01

367

Populations of metastable and resonant argon atoms in radio frequency magnetron plasmas used for deposition of indium-zinc-oxide films  

SciTech Connect

This work reports optical absorption spectroscopy measurements of the number density of Ar atoms in resonant ({sup 3}P{sub 1}, {sup 1}P{sub 1}) and metastable ({sup 3}P{sub 2}, {sup 3}P{sub 0}) states in rf magnetron sputtering plasmas used for the deposition of ZnO-based thin films. While the density of Ar {sup 3}P{sub 2} and {sup 3}P{sub 0} was fairly independent of pressure in the range of experimental conditions investigated, the density of Ar {sup 3}P{sub 1} and {sup 1}P{sub 1} first sharply increased with pressure and then reached a plateau at values close to those of the {sup 3}P{sub 2} and {sup 3}P{sub 0} levels at pressures above about 50 mTorr. At such pressures, ultraviolet radiation from resonant states becomes trapped such that these levels behave as metastable states. For a self-bias voltage of -115 V and pressures in the 5-100 mTorr range, similar number densities of Ar resonant and metastable atoms were obtained for Zn, ZnO, and In{sub 2}O{sub 3} targets, suggesting that, over the range of experimental conditions investigated, collisions between these excited species and sputtered Zn, In, and O atoms played only a minor role on the discharge kinetics. The metastable-to-ground state number density ratios were also fitted to the predictions of a global model using the average electron temperature, T{sub e}, as the only adjustable parameter. For all targets examined, the values of T{sub e} deduced from this method were in excellent agreement with those obtained from Langmuir probe measurements.

Maaloul, L.; Morel, S.; Stafford, L. [Departement de Physique, Universite de Montreal, Montreal, Quebec, H3C 3J7 (Canada)

2012-03-15

368

Thermal conduction energy loss in an argon afterglow  

Microsoft Academic Search

The decay of neutral gas temperature in low pressure argon afterglows has been measured by monitoring the acoustic standing waves excited by the ionizing discharge, with a microwave interferometer. Calculations, based on heat loss by atom thermal conduction only, give very good agreement with experimental results over a wide range of plasma conditions.

T P Sorensen; M C Sexton

1970-01-01

369

The contact phase of coagulation in the presence of heparin.  

PubMed

The effect of heparin on the contact phase of coagulation has been investigated by a technique utilizing a solution of toluidine blue in calcium chloride. Heparin in a concentration of 7 units/ml. of plasma does not inhibit contact activation by glass. It is suggested that heparin does not prevent the activation of factor XII (Hageman factor) by glass or the subsequent formation of active factor XI (plasma thromboplastin antecedent). PMID:13971779

BLOOM, A L

1962-11-01

370

Depleted argon from underground sources  

SciTech Connect

Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic {sup 39}Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in {sup 39}Ar. In Cortez Colorado a CO{sub 2} well has been discovered to contain approximately 500ppm of argon as a contamination in the CO{sub 2}. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N{sub 2}, and He mixture, from the CO{sub 2} through chromatographic gas separation. The N{sub 2} and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.

Back, H.O.; /Princeton U.; Alton, A.; /Augustana U. Coll.; Calaprice, F.; Galbiati, C.; Goretti, A.; /Princeton U.; Kendziora, C.; /Fermilab; Loer, B.; /Princeton U.; Montanari, D.; /Fermilab; Mosteiro, P.; /Princeton U.; Pordes, S.; /Fermilab

2011-09-01

371

Preservation of coagulation efficiency of Moringa oleifera , a natural coagulant  

Microsoft Academic Search

In recent years, there has been an interest to useMoringa oleifera as the natural coagulant due to cost, associated health and environmental concerns of synthetic organic polymers and inorganic\\u000a chemicals. However, it is known thatM. oleifera as the natural coagulant is highly biodegradable and has a very short shelf life. This research was carried out to investigate\\u000a the effects of

S. Katayon; S. C. Ng; M. M. N. Megat Johari; L. A. Abdul Ghani

2006-01-01

372

Experiments with a Large Sized Hollow Cathode Discharge Fed with Argon, Part 2.  

National Technical Information Service (NTIS)

Results of measurements made on the positive column of a large sized hollow cathode discharge in argon are presented. The plasma is in a stationary state and fully ionized (though charge exchange collisions with neutral particles are still of importance)....

F. Boeschoten D. J. Kleijn R. Komen W. F. H. Merck A. F. C. Sens

1975-01-01

373

Coagulation defects in rabbits after infusion of dispersed fluorochemicals.  

PubMed

Coagulation parameters were studied in rabbits during and after intravenous infusion of suspensions of dispersed fluorochemicals. Blood samples from rabbits given dispersed perfluorobutyltetrahydrofurane or perfluorotributylamine showed thrombocytopenia, prolongation of activated partial thromboplastin time, and decreases in Factors X and XI. The possible presence of an inhibitor of coagulation was suggested by the prolongation of prothrombin time when measured with serial dilutions of thromboplastin reagent. These abnormalities were not found in whole blood or platelet-rich plasma after incubation in vitro with dispersed fluorochemical. PMID:128161

Lau, P; Shankar, V S; Mayer, L L; Wurzel, H A; Sloviter, H A

374

The relationship between factor XI coagulant and factor XI antigenic activity in cattle.  

PubMed Central

Factor XI protein, isolated from normal bovine plasma, was used to raise antiserum in rabbits. The antisera was partially purified and used in a neutralization-inhibition assay to investigate the relationship between factor XI coagulant activity and antigenic material in the plasma of normal cattle and cattle homozygous and heterozygous for factor XI deficiency. Factor XI antigen was reduced in both the homozygous and heterozygous animals to levels comparable to the factor XI coagulant activity. The reduction of immunologically cross-reactive material to normal factor XI suggests that the factor XI coagulation defect is associated with the absence of a normal protein.

Gentry, P A

1984-01-01

375

Synthesis of Carbon Nanostructures by Using Thermal Plasma Torch  

Microsoft Academic Search

Some recent results concerning the synthesis of carbon nanostructures in a thermal plasma generating by a plasma torch are presented. Several tests were carried out in different operational conditions. The plasma was formed with argon and different gas mixtures of argon-acetylene or argon-methane to which some catalyst materials (ferrocene and cerium oxide) were added. These catalysts were introduced into the

M. Pacheco; J. Pacheco; M. Valdivia; L. Bernal; R. Valdivia; A. Huczko; H. Lange; A. Cruz; R. López-Callejas

2004-01-01

376

Whole blood coagulation analyzers.  

PubMed

Whole blood Coagulation analyzers (WBCAs) are widely used point-of-care (POC) testing devices found primarily in cardiothoracic surgical suites and cardia catheterization laboratories. Most of these devices can perform a number of coagulation tests that provide information about a patient's blood clotting status. Clinicians use the results of the WBCA tests, which are available minutes after applying a blood sample, primarily to monitor the effectiveness of heparin therapy--an anticoagulation therapy used during cardiopulmonary bypass (CPB) surgery, angioplasty, hemodialysis, and other clinical procedures. In this study we evaluated five WBCAs from four suppliers. Our testing focused on the applications for which WBCAs are primarily used: Monitoring moderate to high heparin levels, as would be required, for example, during CPB are angioplasty. For this function, WCBAs are typically used to perform an activated clotting time (ACT) test or, as one supplier refers to its test, a heparin management test (HMT). All models included in this study offered an ACT test or an HMT. Monitoring low heparin levels, as would be required, for example,during hemodialysis. For this function, WBCAs would normally be used to perform either a low-range ACT (LACT) test or a whole blood activated partial thromboplastin time (WBAPTT) test. Most of the evaluated units could perform at least one of these tests; one unit did not offer either test and was therefore not rated for this application. We rated and ranked each evaluated model separately for each of these two applications. In addition, we provided a combined rating and ranking that considers the units' appropriateness for performing both application. We based our conclusions on a unit's performance and humans factor design, as determined by our testing, and on its five-year life-cycle cost, as determined by our net present value (NPV) analysis. While we rated all evaluated units acceptable for each appropriate category, we did identify some significant differences that enabled us to rank the units in order of preference. We have included a Selection, Purchasing, and use guide at the end of this study to help facilities identify the unit that will best meet their needs. PMID:9283920

1997-08-01

377

Coagulation of Microcrystalline Cellulose Dispersions.  

National Technical Information Service (NTIS)

The coagulation effects on microcrystalline cellulose sols of simple ions, hydrolyzed metal ions, chelate complexes, and a series of alkylammonium chlorides differing in length of the hydrocarbon chain have been investigated. It was found that these sols ...

S. Kratohvil G. E. Janauer E. Matijevic

1968-01-01

378

Some Experiments in Potassium-Argon Dating  

Microsoft Academic Search

In the usual potassium-argon dating method, potassium and argon analyses are each performed on a separate sample. However, this procedure sometimes leads to an erroneous age result because of the inhomogeneous distribution of potassium and argon in minerals. Hence, it is quite desirable to do both the potassium and argon analyses on the same aliquot of sample to eliminate this

Minoru Ozima

1959-01-01

379

Conventional and optimized coagulation for NOM removal  

Microsoft Academic Search

The evaluation of 16 sites with optimized coagulation (optimizing the pH of coagulation and then the coagulant dosage) provides an assessment of this coagulation technique and illustrates its capabilities to meet the requirements of the Disinfectants\\/Disinfection By-products (D\\/DBP) Rule. Jar tests were used to determine the effectiveness of optimized coagulation for the removal of organic carbon, DBP precursors, particles, and

Kimberly Bell-Ajy; Morteza Abbaszadegan; Eva Ibrahim; Debbie Verges; Mark LeChevallier

2000-01-01

380

Argon SDC detector cryogenic design.  

National Technical Information Service (NTIS)

A first cut at designing the cryogenic systems is resented. The point design or sample design presented includes flow-rate calculations, piping sizes, dewar elevations, etc. In summary, the analysis shows argon cooling is ample even with relatively small ...

D. S. Slack

1991-01-01

381

Electrical conductivity of compressed argon  

SciTech Connect

The authors report calculations of the electrical conductivity of solid argon as a function of compression within the density functional local density approximation formulation for a norm-conserving pseudopotential using both electron-phonon coupling and molecular dynamics techniques.

Bauer, R. [Univ. Regensburg (Germany); Windl, W.; Collins, L.; Kress, J.; Kwon, I. [Los Alamos National Lab., NM (United States)

1997-10-01

382

Upregulation of the Coagulation Factor VII Gene during Glucose Deprivation Is Mediated by Activating Transcription Factor 4  

Microsoft Academic Search

BackgroundConstitutive production of blood coagulation proteins by hepatocytes is necessary for hemostasis. Stressful conditions trigger adaptive cellular responses and delay processing of most proteins, potentially affecting plasma levels of proteins secreted exclusively by hepatocytes. We examined the effect of glucose deprivation on expression of coagulation proteins by the human hepatoma cell line, HepG2.Methodology\\/Principal FindingsExpression of coagulation factor VII, which is

Katherine R. Cronin; Thomas P. Mangan; Josephine A. Carew

2012-01-01

383

[Examination of the sample centrifugation time for emergency coagulation test].  

PubMed

The rapidity of coagulation testing is important for use as appropriate substitution therapy in patients with, or at risk of critical bleeding requiring massive transfusion. Whereas the ordinary method of coagulation testing is known to be slow, in a critically haemorrhaging patient, a rapid turnaround time of coagulation testing becomes indispensable. To find out if coagulation test results will be affected by a shortened centrifugation time, we measured PT (prothrombin time), APTT (activated partial thromboplastin time), FIB (fibrinogen) and PLT (platelet) in plasma, using different centrifugation times (10 min, 5 min, 3 min), and analyzed the measurements. We found that, whereas centrifugation time significantly affected the PLT count in plasma (10 min; 5.17 +/- 3.71 x 10(3)/microl, 5min; 28. +/- 26.9 x 10(3)/microl, 3min; 63.7 x 10(3)/microl), PT(10min; 14.6 +/- 5.76 sec, 5min; 14.7 +/- 5.84 sec, 3min; 14.9 +/- 6.40 sec), APTT (10min; 36.4 +/- 15.9 sec, 5min; 36.8 +/- 16.5 sec, 3min; 34.7 +/- 11.4 sec) and FIB(10min; 361 +/- 134 mg/dl, 5min; 356 +/- 132 mg/dl, 3min; 356 +/- 125 mg/dl) were not affected. These data suggest that shortening centrifugation time will have no significant effect on the value of PT, APTT and FIB, in an emergency situation. PMID:23383570

Watanabe, Yumi; Kawahara, Yoshie; Hanada, Daisuke; Nozawa, Keisuke; Tomoda, Yutaka; Kino, Shuichi

2012-11-01

384

Argon-40-argon-39 dating of apollo sample 15555.  

PubMed

An age of 3.33+/-0.05x10(9) years was obtained for Apollo 15 sample 15555 by argon40-argon-39 dating. The age of rock 15555, a basalt from the rim of Hadley Rille, establishes an upper limit to the age of the rille. The basalt flows filling the Hadley Rille section of the Imbrium basin postdate the formation of the basin-as measured by the Apollo 14 samples of the Fra Mauro formation-by at least 500x10(6) years. Therefore, the mare basalts cannot be simple impact melts but rather must result from some igneous activity on the moon. PMID:17731360

Alexander, E C; Davis, P K; Lewis, R S

1972-01-28

385

Effect of Plant Originated Coagulants and Chymosin on Ovine Milk Coagulation  

Microsoft Academic Search

The coagulation of ewe's milk was studied by using plant source coagulants namely the artichoke, Cynara scolymus L. cv. Blanca, and latex from the fig tree (Ficus carica L.). A turbidimetric method was used to evaluate and compare the coagulation properties of the novel coagulants with chymosin treated samples. Syneresis capacity and sensory evaluation of resultant cheese samples were studied

Salwa Bornaz; Nejib Guizani; Nizar Fellah; Ali Sahli; Mourad Ben Slama; Hamadi Attia

2010-01-01

386

Application of psyllium husk as coagulant and coagulant aid in semi-aerobic landfill leachate treatment  

Microsoft Academic Search

Landfill leachate is a heavily polluted and a likely hazardous liquid that is produced as a result of water infiltration through solid wastes generated industrially and domestically. This study investigates the potential of using psyllium husk as coagulant and coagulant aid for the treatment of landfill leachate. Psyllium husk has been tested as primary coagulant and as coagulant aid with

Yasir A. J. Al-Hamadani; Mohd Suffian Yusoff; Muhammad Umar; Mohammed J. K. Bashir; Mohd Nordin Adlan

2011-01-01

387

The Mechanism of Organic Removal During Coagulation  

Microsoft Academic Search

Coagulation is a common water treatment step primarily designed to aggregate and thereby help remove true particulate (turbidity causing) matter. Organic compounds of natural origin (i.e. humic and fulvic acids) have also been observed to be removed by Coagulation. This research was designed primarily to identify the limiting mechanisms responsible for the removal of natural organics by the coagulation process.

Jean-Luc Bersillon

1983-01-01

388

Treatment of tannery wastewater by chemical coagulation  

Microsoft Academic Search

The objective of this study was to develop a treatment system that can effectively reduce the concentration of pollutants in tannery wastewater to environmentally acceptable levels and that can greatly reduce the cost of discharging the effluents. Aluminium sulphate and ferric chloride were used as a coagulant in the process. The influence of pH and coagulant dosages on the coagulation

Z Song; C. J Williams; R. G. J Edyvean

2004-01-01

389

Initial DAB Argon Storage Dewar Leakage.  

National Technical Information Service (NTIS)

Any detectable leakage emanating from the argon storage dewar is undesirable; not only from a safety standpoint (eg, cryogenic burns, asphyxiation, etc.), but also small amounts of air back diffusing through leaks can render the argon unsuitable for the f...

K. Dixon

1990-01-01

390

[Coagulation management during liver transplantation].  

PubMed

In the course of liver transplantation many patients develop coagulation and bleeding disorders. On the other hand, some patients suffer thromboembolic events in the perioperative period with sometimes fatal outcome. For this reason, in 1999 we changed our coagulation management for liver transplantation and abolished the routine prophylaxis with antifibrinolytic drugs. In this context we implemented the ROTEM system (Pentapharm GmbH, Munich) in our perioperative point-of-care coagulation management. From 2000 to 2005, we analysed more than 18,000 ROTEM measurements in the context of 642 liver transplantations. Prophylactic administration of antifibrinolytic drugs was only done in patients with fulminant liver failure or if MCF in ExTEMcoagulation management for liver transplantation. PMID:16953295

Görlinger, K

2006-08-01

391

Hemostasis and Coagulation: Theoretical Concepts.  

National Technical Information Service (NTIS)

The review cites leading articles which deal directly with the formation of theories of coagulation as they exist today. Many of the papers cited were written because of a search for the cause and cure of hemophilia; therefore, this subject is dealt with ...

J. D. Bairrington

1966-01-01

392

Physical Activity Status and Adverse Age-Related Differences in Coagulation and Fibrinolytic Factors in Women  

Microsoft Academic Search

Adverse changes in coagulation and fibrinolytic factors are thought to contribute to the increased risk of cardiovascular disease and atherothrombosis with age. We tested the hypothesis that such age-related changes in specific coagulation and fibrinolytic factors are absent in physically active women. Resting levels of plasma fibrinogen, tissue-type plasminogen activator (t-PA) antigen and activity, plasminogen activator inhibitor-1 (PAI-1) antigen and

Christopher A. DeSouza; Pamela Parker Jones; Douglas R. Seals

393

Argon39 and tritium in meteorites  

Microsoft Academic Search

The radioactive isotopes argon-39 and tritium are measured in a number of iron and stone meteorites. The stable isotope helium-3 is also measured and the argon-38 content is estimated from the helium-3 content. The cosmic ray exposure ages obtained from the argon-39 and argon-38 are: 4·2 × 10 8 years for the Sikhote-Alin iron meteorite, 4·5 × 10 8 years

E. L. Fireman; J. Defelice

1960-01-01

394

Effect of argon additive on H- density and temperature in volume negative ion source  

NASA Astrophysics Data System (ADS)

Various plasma parameters were measured for several hydrogen-argon mixtures in the multicusp H- ion source Camembert III, equipped with tantalum filaments. The density and the temperature of electrons were measured with the Langmuir probe situated in the center of the source and associated with the photodetachment diagnostics. The two-laser photodetachment diagnostics was used to obtain the temperatures of the two negative ion populations. At low hydrogen pressure (0.8 mTorr) a small concentration of argon additive enhances the hydrogen negative ion density (by approximately 60%), it also increases the electron density. The negative ion population fractions having the high- and low-temperature values behave differently when varying the total pressure in pure hydrogen and in hydrogen with argon additive. Several possible explanations of the drastic change of the relative ratio of negative ion populations when the argon fraction is increased, are proposed. Another interesting phenomenon observed during the experiments is the decrease with time of the H- density in the presence of argon. After adding the argon during the time interval of ~1 h the H- density goes down and finally establishes at a minimum value. The final H- density is lower than the H- density in pure hydrogen plasma before adding argon. This ``poisoning'' is discussed in terms of wall production of vibrationally excited H2 molecules.

Ivanov, A. A.; Bacal, M.; Rouillé, C.; Nishiura, M.; Sasao, M.

2004-05-01

395

Neutron Scattering from Liquid Argon  

Microsoft Academic Search

Extensive measurements of slow-neutron inelastic scattering from liquid argon at 84.5°K have been made using cold and thermal neutrons. The cold-neutron experiments were performed using a rotating-crystal spectrometer. A triple-axis spectrometer in its \\

B. A. Dasannacharya; K. R. Rao

1965-01-01

396

Role of endothelin in disseminated intravascular coagulation.  

PubMed

We examined the changes in plasma levels of endothelin-1 (ET-1), a potent vasoconstrictor peptide, in 47 cases of disseminated intravascular coagulation (DIC) to investigate the role of ET-1 in DIC and its relation to multiple organ failure (MOF). A significant elevation of plasma levels of ET-1 was observed in some cases of DIC, especially in patients with sepsis, blastic crisis of chronic myelogenous leukemia, and cancer. However, no such significant elevation was observed in patients with acute promyelocytic leukemia (APL), acute leukemias except for APL, or non-Hodgkin lymphoma. Plasma levels of ET-1 were higher in patients with DIC with MOF than in those without MOF. Although the levels of ET-1 were decreased or remained low with clinical improvement in most DIC patients, the levels were further increased or remained high in patients who showed no improvement in DIC. It is suggested that ET-1 must play an important role in further progression of MOF with the vasoconstriction and microcirculatory disorders. PMID:1415185

Asakura, H; Jokaji, H; Saito, M; Uotani, C; Kumabashiri, I; Morishita, E; Yamazaki, M; Matsuda, T

1992-10-01

397

Automated Amidolytic Method for Evaluating the Activated Partial Thromboplastin Time Compared with a Conventional Coagulation Method  

Microsoft Academic Search

We report studies of the validity and clinical application of a new amidolytic method for evaluating the activated partial thromboplastin time (APTT) compared with a conventional clotting method. The results with the two methods were well correlated for normal plasma and plasma from hemophilia patients. Congenital deficiencies of the intrinsic coagulation pathway other than hypo- and dysfibrinogenemia detected by the

A. Tripodi; M. Poggio; L. Scapellato; P. M. Mannucci

1989-01-01

398

Theoretical and experimental comparisons of Gamble II argon gas puff experiments  

Microsoft Academic Search

Summary form only given. A one-dimensional radiative magnetohydrodynamic (MHD) analysis of an imploding argon gas puff plasma was performed. The calculations were set up to approximate the conditions of a series of argon gun puff experiments that were carried out on the NRL Gamble II generator. Annular gas puffs (2.5-cm diameter) imploded with a 1.2-MA peak driving current for different

J. W. Thornhill; F. C. Young; K. G. Whitney; J. Davis; S. J. Stephanakis

1990-01-01

399

A novel role for pro-coagulant microvesicles in the early host defense against streptococcus pyogenes.  

PubMed

Previous studies have shown that stimulation of whole blood or peripheral blood mononuclear cells with bacterial virulence factors results in the sequestration of pro-coagulant microvesicles (MVs). These particles explore their clotting activity via the extrinsic and intrinsic pathway of coagulation; however, their pathophysiological role in infectious diseases remains enigmatic. Here we describe that the interaction of pro-coagulant MVs with bacteria of the species Streptococcus pyogenes is part of the early immune response to the invading pathogen. As shown by negative staining electron microscopy and clotting assays, pro-coagulant MVs bind in the presence of plasma to the bacterial surface. Fibrinogen was identified as a linker that, through binding to the M1 protein of S. pyogenes, allows the opsonization of the bacteria by MVs. Surface plasmon resonance analysis revealed a strong interaction between pro-coagulant MVs and fibrinogen with a KD value in the nanomolar range. When performing a mass-spectrometry-based strategy to determine the protein quantity, a significant up-regulation of the fibrinogen-binding integrins CD18 and CD11b on pro-coagulant MVs was recorded. Finally we show that plasma clots induced by pro-coagulant MVs are able to prevent bacterial dissemination and possess antimicrobial activity. These findings were confirmed by in vivo experiments, as local treatment with pro-coagulant MVs dampens bacterial spreading to other organs and improved survival in an invasive streptococcal mouse model of infection. Taken together, our data implicate that pro-coagulant MVs play an important role in the early response of the innate immune system in infectious diseases. PMID:23935504

Oehmcke, Sonja; Westman, Johannes; Malmström, Johan; Mörgelin, Matthias; Olin, Anders I; Kreikemeyer, Bernd; Herwald, Heiko

2013-08-01

400

Argon-krypton ion laser as light source for medical photocoagulation applications  

NASA Astrophysics Data System (ADS)

Photocoagulators are one of the most popular laser devices in medicine. Due to different kind of interaction of particular wavelength range of laser light with live tissues, sources of laser radiation which can cover as much as possible of visible spectrum are still very wanted (see [1,2]). In last years it also can be observed the intensive developing works on new photocoagulation technique called "micropulse coagulation" [3,4]. The most critical feature of lasers for micropulse coagulation is the possibility of fast switching between two selected laser power values. It seems that the good proposal for these applications can be ion laser filled with argon-krypton mixture. Authors previously have indicated the possibility of improvement of generation conditions in this type of laser in presence of buffer gases [5,6] and with use developed by authors pulse supply regime [7,8]. These improvements allow to obtain output power values of most important argon and krypton laser lines in laser filled with mixture of both gases, similar to values available in laser filled with pure gases. Presented in this paper the following researches are concerned on verification of possibilities of use of the developed laser system in photocoagulation with possibility of use of the laser system in micropulse coagulation technique.

Kami?ski, Wojciech; Warda, Piotr; Kasprzak, Jan; Kesik, Jerzy

2013-01-01

401

Factors involved in sudden coagulation observed in patients with acute myocardial infarction.  

PubMed

Coronary artery diseases (CAD) evolving into acute myocardial infarction (AMI) is associated with coagulation and thrombotic occlusion of coronary vessels in the presence of unstable atheroma. The atheromatous plaque becomes unstable when it is infiltrated by monocytes, macrophages and neutrophils capable of secreting proteases that induce plaque erosion, rupture and initialize the coagulation process. The aim of this study was (a) to analyse the plasma of patients with AMI for the presence of proteases that may activate rapid coagulation, (b) to evaluate coagulation markers as prothrombin fragment (F1+2) and antithrombin III and (c) to find an interrelation between proteases and coagulation markers. The examined plasma showed high values of prothrombin fragment (F1+2) and low levels of antithrombin III. These markers showed a highly significant negative-correlation. The plasma also exhibited increased levels of matrix metalloproteinase-9 (MMP-9) which were positively-correlated with the prothrombin fragment (F1+2). MMP-9 seems to cause the coagulation activity by increasing the level of prothrombin fragment (F1+2) and the consumption of antithrombin III. The examined plasma also exhibited high levels of neutrophil gelatinase-associated lipocalin (NGAL), which is known to modulate MMP-9 activity. The high plasma levels of MMP-9 and NGAL can be attributed to plaque instability and appear to activate sudden coagulation. MMP-9 and NGAL, in the presence of altered values of prothrombin fragment (F1+2) and antithrombin III in AMI patients, seem to be suitable markers to be studied in unstable plaque patients, for the prediction and prevention of acute coronary syndrome. PMID:23160687

Pinelli, Arnaldo; Trivulzio, Silvio; Rossoni, Giuseppe; Redaelli, Rosaria; Brenna, Sergio

402

Hollow Cathode Discharge: Arc Regime with Interior Positive Column in a Flow of Argon.  

National Technical Information Service (NTIS)

The plasma generated in the hollow cathode was investigated. The device used comprises a cathode and an anode with a central orifice through which the plasma is ejected. The anode is placed at the cathode outlet. The study of argon flow inside the cathode...

A. Brunet

1976-01-01

403

Hollow Cathode Discharge: Arc Regime with Interior Positive Column in Argon Flow.  

National Technical Information Service (NTIS)

Plasma generated in the cathode is dealt with. The device used comprises a cathode and an anode with a central orifice through which the plasma is ejected. The anode is placed at the cathode outlet. The study of argon flow inside the cathode emphasized th...

A. Brunet

1975-01-01

404

Hollow cathode discharge: Arc regime with interior positive column in argon flow  

Microsoft Academic Search

Plasma generated in the cathode is dealt with. The device used comprises a cathode and an anode with a central orifice through which the plasma is ejected. The anode is placed at the cathode outlet. The study of argon flow inside the cathode emphasized the presence of a sonic flow in the cathode outlet section. Assuming the gas temperature equal

A. Brunet

1975-01-01

405

Hollow cathode discharge: Arc regime with interior positive column in a flow of argon  

Microsoft Academic Search

The plasma generated in the hollow cathode was investigated. The device used comprises a cathode and an anode with a central orifice through which the plasma is ejected. The anode is placed at the cathode outlet. The study of argon flow inside the cathode emphasized the presence of a sonic flow in the cathode outlet section. Assuming the gas temperature

A. Brunet

1976-01-01

406

Argon-40/ argon-39 dating of lunar rock samples.  

PubMed

Seven crystalline rock samples returned by Apollo 11 have been analyzed in detail by means of the (40)Ar-(-39)Ar dating technique. The extent of radiogenic argon loss in these samples ranges from 7 percent to >/= 48 percent. Potassium-argon ages, corrected for the effects of this loss, cluster relatively closely around the value of 3.7 x 10(9) years. Most of the vulcanism associated with the formation of the Mare Tranquillitatis presumably occurred around 3.7 x 10(9) years ago. A major cause of the escape of gas from lunar rock is probably the impact event which ejected the rock from its place of origin to its place of discovery. Upper limits for the times at which these impact events occurred have been estimated. PMID:17781454

Turner, G

1970-01-30

407

[Disturbances in coagulation, fibrinolytic and complement systems in septic shock].  

PubMed

Plasma levels of selected proteins of coagulation, fibrinolysis and complement from patients with septic shock have been investigated. All values were corrected on the basis of a plasma protein content of 5.5%. Considerable decreases were found in the plasma levels of the contact factors activity. The antigen content in the case of HMW-kininogen remained in the normal range, whereas in the case of prekallikrein it dropped to about 30% of norm. Considering the proteins of the unspecific defense and the complement system, primarily HRG, alpha 2-macroglobulin and C4 showed remarkable decreases. From the changes of the plasma levels of the considered proteins one can conclude that in septic shock primarily the contact phase of coagulation and the alternative pathway of complement are involved. The consumption of F XIII points to a thrombin generation during shock. The marked reduction of the C4-component could be due to an isolated proteolysis of this component, since the classical pathway of complement activation seems not to be involved in the shock events. Serial controls of the plasma levels of the proteins under investigation showed in some patients considerable individual deviations from the general trend. A considerable increase of the F XIII A level appears to be a prognostically favorable result, whereas constantly low values of F XIII and fibronectin without a tendency to normalization or a constant decrease of these proteins often is connected with a fatal outcome. PMID:3718404

Karges, H E; Egbring, R; Merte, D

1986-02-01

408

Blood coagulation dynamics: mathematical modeling and stability results.  

PubMed

The hemostatic system is a highly complex multicomponent biosystem that under normal physiologic conditions maintains the fluidity of blood. Coagulation is initiated in response to endothelial surface vascular injury or certain biochemical stimuli, by the exposure of plasma to Tissue Factor (TF), that activates platelets and the coagulation cascade, inducing clot formation, growth and lysis. In recent years considerable advances have contributed to understand this highly complex process and some mathematical and numerical models have been developed. However, mathematical models that are both rigorous and comprehensive in terms of meaningful experimental data, are not available yet. In this paper a mathematical model of coagulation and fibrinolysis in flowing blood that integrates biochemical, physiologic and rheological factors, is revisited. Three-dimensional numerical simulations are performed in an idealized stenosed blood vessel where clot formation and growth are initialized through appropriate boundary conditions on a prescribed region of the vessel wall. Stability results are obtained for a simplified version of the clot model in quiescent plasma, involving some of the most relevant enzymatic reactions that follow Michaelis-Menten kinetics, and having a continuum of equilibria. PMID:21631138

Sequeira, Adélia; Santos, Rafael F; Bodnár, Tomás

2011-04-01

409

Half-Lives of Argon-37, Argon-39, and Argon-42.  

PubMed

The half-lives of three argon isotopes have been carefully determined, with the following results: Ar(37), 35.1 +/- 0.1 days; Ar(39) 269 +/- 3 years; Ar(42), 32.9 +/- 1.1 years. By combining the Ar(42) value with earlier data, a cross section of 0.5 +/- 0.1 barn is calculated for the reaction, with thermal neutrons, Ar(41)(n,gamma)Ar(42). PMID:17791262

Stoenner, R W; Schaeffer, O A; Katcoff, S

1965-06-01

410

Rate Process of the Coagulation of Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanometer-sized gold particles dispersed in organic liquids coagulate under the influence of addition of salt or illumination of Mie resonance irradiation. It is derived that the van der Waals attractive force can be enhanced by the excitation of surface plasmon, hence the rate of coagulation is accelerated through the DLVO (Derjaguin, Landau, Verway, Overbeek) potential among the particles. The coagulation rate and the stability ratio are calculated within a framework of DLVO theory.

Kimura, K.

411

Coagulation disorders after traumatic brain injury  

Microsoft Academic Search

Summary  \\u000a Background. Over the past decade new insights in our understanding of coagulation have identified the prominent role of tissue factor.\\u000a The brain is rich in tissue factor, and injury to the brain may initiate disturbances in local and systemic coagulation. We\\u000a aimed to review the current knowledge on the pathophysiology, incidence, nature, prognosis and treatment of coagulation disorders\\u000a following

B. S. Harhangi; E. J. O. Kompanje; F. W. G. Leebeek; A. I. R. Maas

2008-01-01

412

Interactions between alum and organics in coagulation  

Microsoft Academic Search

The coagulation-sedimentation process, i.e. a major pretreatment for filtration, has the potential to remove organic contaminants. However, interactions between coagulants and organics in the absence of suspended solids have only received limited attention. This study aims to model alum-organics' interactions corresponding to the behavior of organics during coagulation. Two typical organic materials, humic acid and salicylic acid, are investigated. Experimental

Chihpin Huang; Hueiling Shiu

1996-01-01

413

[Introduction of international normalized ratio of prothrombin time to evaluate multiple depletions of coagulation factors].  

PubMed

Prothrombin time(PT) is utilized in worldwide as a global coagulation test reflected multiple depletions of coagulation factors in diseases such as severe liver dysfunction and Disseminated Intravascular Coagulation(DIC). However, standardization of regents and result reporting methods are not established yet except International Normalized Ration(INR) for control of oral anticoagulant therapy(OAT). We evaluated whether INR is capable for defect of multiple coagulation factors except OAT, using absorbed plasma and different origins of thromboplastin; human recombinant, human placenta, cultured human cell and rabbit brain. PTs of individual 90 samples(group MC) absorbed with BaSO4 and/or bentnite and 60 samples(group W) from patients with OAT were measured with 20 normal plasmas with respective reagents. Sensitivities of four reagents to plasma of group W and MC were determined respectively against human recombinant thromboplastin(ISI = 1.03). Both of human thromboplastin showed that sensitivity to absorbed plasma was very close to OAT plasma, whereas reductions of sensitivity to 84% and 66% for absorbed plasma were revealed in both of rabbit thromboplastins. Correlations of INRs calculated by two different sensitivities, one is to absorbed plasma and another to OAT plasma, indicated that discrepancy of sensitivities was emphasized as large slopes(1.50 and 2.76) of regression lines and large intercepts in rabbit thromboplastins, although slopes closed to 1.0 with small intercepts in both of human thromboplastins. We concluded that use of human thromboplastin was the first priority to introduce INR system for evaluation of multiple coagulation factors depletions. PMID:12166083

Fujita, Susumu; Kagawa, Kazuhiko; Fukutake, Katsuyuki

2002-06-01

414

Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon/nitrogen  

SciTech Connect

In this letter, atmospheric-pressure glow discharges in {gamma} mode with argon/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the {alpha}-{gamma} coexisting mode or {gamma} mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen, can be employed to generate the stable {gamma} mode radio-frequency, atmospheric-pressure glow discharges and the discharge voltage rises with increasing the fraction of nitrogen in the argon-nitrogen mixture for a constant total gas flow rate.

Wang Huabo; Sun Wenting; Li Heping; Bao Chengyu; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)

2006-10-16

415

Enhanced coagulation for high alkalinity and micro-polluted water: The third way through coagulant optimization  

Microsoft Academic Search

Conventional coagulation is not an effective treatment option to remove natural organic matter (NOM) in water with high alkalinity\\/pH. For this type of water, enhanced coagulation is currently proposed as one of the available treatment options and is implemented by acidifying the raw water and applying increased doses of hydrolyzing coagulants. Both of these methods have some disadvantages such as

Mingquan Yan; Dongsheng Wang; Jiuhui Qu; Jinren Ni; Christopher W. K. Chow

2008-01-01

416

Boltzmann expansion in a radiofrequency conical helicon thruster operating in xenon and argon  

NASA Astrophysics Data System (ADS)

A low pressure (~0.5 mTorr in xenon and ~1 mTorr in argon) Boltzmann expansion is experimentally observed on axis within a magnetized (60 to 180 G) radiofrequency (13.56 MHz) conical helicon thruster for input powers up to 900 W using plasma parameters measured with a Langmuir probe. The axial forces, respectively, resulting from the electron and magnetic field pressures are directly measured using a thrust balance for constant maximum plasma pressure and show a higher fuel efficiency for argon compared to xenon.

Charles, C.; Boswell, R.; Takahashi, K.

2013-06-01

417

Genetic engineering and coagulation factors.  

PubMed

It is unfortunate that we cannot report, in the area of coagulation, advances that have been seen in related fields such as thrombolytic therapy. The reported progress (Gold et al, 1984; Van de Werf et al, 1984) with human recombinant tissue plasminogen activator (Pennica et al, 1983) augers well for the application of recombinant technology to the problems faced by patients with coagulation defects. While plasminogen activator is being assessed in an acute therapeutic setting, its use signals a beginning of the application of the technology to abnormalities of the haemostatic mechanism. Chronic administration of coagulation factors for prophylaxis and replacement therapy would appear to be just one more step down the pathway illuminated by the biochemists, microbiologists and cell biologists who have preceded the clinicians in this promising area. There is no record of the use of genetically engineered materials in the treatment of coagulation defects, primarily because the body of knowledge and refined techniques have only recently been acquired. For this reason we have had to project developments in other areas onto the problems that exist for the haemostatically compromised patient. In describing the potential usefulness of these technologies, it is difficult to ascertain where the logical projection, from a fully investigated model system, diverges from flights of imaginative fancy. Cloning projects considered overly ambitious and grandiose at the beginning of this decade are already accomplished feats. The feasibility of gene therapy in the mammalian system has been demonstrated, and trade publications now discuss governmental approval for investigative use of this procedure in 1985. Panels of physicians, scientists and even politicians now seriously contemplate and promulgate views and regulations pertaining to the efficacy and ethics of the use of genetic engineering in the treatment of human disease. The haemophilias will certainly be among the first genetic diseases to be approached with the techniques of recombinant DNA technology. Diagnostic testing, using cloned DNA, is already underway and therapeutic trials are predicted for the near future. Every observer of this rapidly growing field has to define for himself when the future is. For the potential carrier of haemophilia B, the future is now. For the physician managing the patient with a haemophilic inhibitor, the future can't come soon enough. And, for those who are concerned with man's tampering with the gene pools of living things, from viruses to humans, the future comes too quickly to be dealt with in a rational and understanding way. PMID:3930118

Fass, D N; Toole, J J

1985-06-01

418

Liquid Argon Calorimetry for ATLAS  

NASA Astrophysics Data System (ADS)

This summer, the largest collaborative physics project since the Manhattan project will go online. One of four experiments for the Large Hadron Collider at CERN in Geneva, ATLAS, employs over 2000 people. Canadians have helped design, construct, and calibrate the liquid argon calorimeters for ATLAS to capture the products of the high energy collisions produced by the LHC. From an undergraduate's perspective, explore how these calorimeters are made to handle their harsh requirement. From nearly a billion proton-proton collisions a second, physicists hope to discover the Higgs boson and other new fundamental particles.

Robinson, Alan

2008-05-01

419

Prophylactic argon laser coagulation for rhegmatogenous retinal detachment in AIDS patients with cytomegalovirus retinitis  

Microsoft Academic Search

· Background: The incidence of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS)\\u000a reaches 20–45%. Despite aggressive medical treatment, rhegmatogenous retinal detachments develop in up to 30% of the affected\\u000a eyes. Surgical repair is often difficult due to multiple, large and hardly visible retinal holes with vitreal traction. Pars\\u000a plana vitrectomy with instillation of silicone oil is the

Christoph Althaus; Karin U. Loeffler; Martin Schimkat; Tobias Hudde; Rainer Sundmacher

1998-01-01

420

Evaluation of coagulation kinetics using thromboelastometry-methodologic influence of activator and test medium.  

PubMed

Renewed interest has arisen in the use of thromboelastography/thromboelastometry in evaluating coagulation kinetics. The test medium, type of activator, and its concentration may influence the interpretation of coagulation kinetics. This study aimed to investigate methodologic influences of activator and test medium on thromboelastometric parameters of coagulation kinetics. Dynamic clot formation was evaluated by thromboelastometry using whole blood (WB), platelet-rich plasma, or platelet-poor plasma employing different concentrations of extrinsic (tissue factor) and contact activator (synthasil) and with variable concentrations of phospholipids. Plasma samples displayed prolonged clot initiation and enhanced clot propagation compared with WB. Clot firmness was markedly reduced in platelet-poor plasma as compared with platelet-rich plasma and WB. Increasing concentration of activator shortened the clot initiation and increased the velocity of clot propagation, whereas terminal clot firmness remained unaffected. Platelets accelerated clot propagation and raised clot firmness. Phospholipids shortened the time of clot initiation and increased velocity of propagation, while clot firmness remained unchanged. Our results demonstrate that evaluation of coagulation kinetics using thromboelastometry varies according to the composition of the test medium, type, and concentration of activator, as well as the presence and concentration of phospholipids in the test reagent. PMID:20480163

Sørensen, Benny; Fenger-Eriksen, Christian; Christiansen, Kirsten; Larsen, Ole H; Ingerslev, Jørgen

2010-05-18

421

Viscoelasticity of coagulated alumina suspensions  

NASA Astrophysics Data System (ADS)

The solid-to-liquid transition of a model coagulated alumina suspension at concentrations above the gel point was investigated to explore the critical parameter for describing network failure under shear forces. Static (creep and creep-recovery) and dynamic (small and large amplitude oscillatory) shear experiments were combined to examine shear softening in these systems and time-based dependence in the yielding dynamics. The particulate network structure exhibits failure and viscous dissipation under creep and oscillatory shear tests at stress values well below the conventionally defined yield stress. Results from strain recovery tests highlight a time-dependence for failure, where only partial recovery of strain energy was possible once a specific duration of creep was surpassed. The system was observed to fail at a common strain value across all methods of rheology testing. These results are self-consistent, showing a clear transition from the linear to non-linear viscoelastic region for a coagulated material under shear stress. It provides the starting point to incorporate mechanical viscoelastic models to extract time constants for yielding behaviour. This work also presents one of the first reported LAOS and creep results for particulate suspensions using a vane geometry.

Kumar, Ashish; Stickland, Anthony D.; Scales, Peter J.

2012-06-01