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1

Coagulation of Dust Particles in Argon Plasma of RF Discharge  

SciTech Connect

The experiments on coagulation of poly-disperse particles with various size distributions injected into the argon plasma of the magnetron radio-frequency discharge are discussed. The experiments were carried out under the conditions similar to those using dusty plasma for technology applications. Within the created theory the threshold behavior of the coagulation process was explained for the first time, the estimation of the critical particle size for onset of a fast coagulation was made, and the analytical calculation of the coagulation rate of dust particles was performed. The proposed coagulation mechanism makes it possible to describe the typical features of coagulation processes observed in experiments and to explain the effects of attraction and coalescence of highly negatively charged microns size particles.

Mankelevich, Yu. A.; Olevanov, M. A.; Pal, A. F.; Rakhimova, T. V.; Ryabinkin, A. N.; Serov, A. O. [Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, 1(2), Leninskie gory, GSP-1, Moscow 119991 (Russian Federation); Filippov, A. V. [Troitsk Institute for Innovation and Fusion Research, Troitsk 142190, Moscow region (Russian Federation)

2008-09-07

2

Argon plasma coagulation therapy for hemorrhagic radiation proctosigmoiditis  

Microsoft Academic Search

Background: Radiation-induced proctosigmoiditis is a serious complication of pelvic radiation therapy. Rectal bleeding occurs among 6% to 8% of these patients and is extremely difficult to manage. Pharmacotherapy is generally ineffective, whereas surgical treatment is associated with high morbidity and mortality. Argon plasma coagulation is a new method of noncontact electrocoagulation well suited for hemostasis of large bleeding areas. Methods:

Rui A. Silva; António J. Correia; Luís Moreira Dias; Helena Lomba Viana; Rafael Lomba Viana

1999-01-01

3

Histology assessment of bipolar coagulation and argon plasma coagulation on digestive tract  

PubMed Central

AIM: To analyze the effect of bipolar electrocoagulation and argon plasma coagulation on fresh specimens of gastrointestinal tract. METHODS: An experimental evaluation was performed at Hospital das Clinicas of the University of São Paulo, on 31 fresh surgical specimens using argon plasma coagulation and bipolar electrocoagulation at different time intervals. The depth of tissue damage was histopathologically analyzed by single senior pathologist unaware of the coagulation method and power setting applied. To analyze the results, the mucosa was divided in superficial mucosa (epithelial layer of the esophagus and superficial portion of the glandular layer of the stomach and colon) intermediate mucosa (until the lamina propria of the esophagus and until the bottom of the glandular layer of the stomach and colon) and muscularis mucosa. Necrosis involvement of the layers was compared in several combinations of power and time interval. RESULTS: Involvement of the intermediate mucosa of the stomach and of the muscularis mucosa of the three organs was more frequent when higher amounts of energy were used with argon plasma. In the esophagus and in the colon, injury of the intermediate mucosa was frequent, even when small amounts of energy were used. The use of bipolar electrocoagulation resulted in more frequent involvement of the intermediate mucosa and of the muscularis mucosa of the esophagus and of the colon when higher amounts of energy were used. In the stomach, these involvements were rare. The risk of injury of the muscularis propria was significant only in the colon when argon plasma coagulation was employed. CONCLUSION: Tissue damage after argon plasma coagulation is deeper than bipolar electrocoagulation. Both of them depend on the amount of energy used. PMID:25031789

Garrido, Teresa; Baba, Elisa R; Wodak, Stephanie; Sakai, Paulo; Cecconello, Ivan; Maluf-Filho, Fauze

2014-01-01

4

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

5

Argon Plasma Coagulation for the Treatment of Hemorrhagic Radiation Colitis  

PubMed Central

Radiation colitis is a common consequence of pelvic radiation. Its complications may include anemia due to chronic bleeding requiring transfusions. Many of these patients are managed with rectal medications which are often inadequate for control. Argon plasma coagulation (APC) has been well described for its efficacy in treating radiation proctitis. Here we present two cases in whom APC therapy was used to treat severe radiation colitis. We reviewed two cases originally seen at the regional cancer center (Cross Cancer Institute) in Edmonton, Alberta, Canada. Both patients received pelvic radiation for recurrent endometrial cancers and were referred for active bleeding secondary to radiation colitis that had required numerous transfusions. Radiation-induced telangiectasias were found from 10–50 cm in the sigmoid colon. Both patients had significant improvement of symptoms after one session of APC treatment set at 40–60 W and gas flow of 2.0 l/min. There were no complications from the procedures. Neither patient required blood transfusions after the treatment with improvement in their hemoglobin levels and were doing well at 3- and 6-month follow-up. APC can be used effectively to provide immediate and sustained resolution of symptoms in patients with radiation colitis. PMID:22933988

Lam, Mindy C.W.; Parliament, Matthew; Wong, Clarence K.W.

2012-01-01

6

Rectal ulcer: Due to ketoprofen, argon plasma coagulation and prostatic brachytherapy  

PubMed Central

Prostatic brachytherapy with permanent seed implants is a recent and safe radiation therapy technique associated with radiation-induced digestive disease. Argon plasma coagulation procedure is a validated modality in the management of haemorrhagic radiation proctitis, which is known to occasionally induce chronic rectal ulcers. We report here an original case report of an acute painful rectal ulcer as a consequence of the combination of short-term therapy with non-steroidal anti-inflammatory drugs therapy, prostatic brachytherapy with malposition of seed implants and argon plasma coagulation procedure in a patient with haemorrhagic radiation proctitis. The description of this clinical observation is essential to recommend the discontinuation of non-steroidal anti-inflammatory drugs therapy and the control of the position of seed implants in case of prostatic brachytherapy before argon plasma coagulation for radiation-induced proctitis. PMID:25493041

Koessler, Thibaud; Servois, Vincent; Mariani, Pascale; Aubert, Emilie; Cacheux, Wulfran

2014-01-01

7

Restoration of the normal squamous lining in Barrett's esophagus by argon beam plasma coagulation  

Microsoft Academic Search

Objective:Barrett's esophagus is associated with significantly increased risk of development of esophageal adenocarcinoma. Replacing columnar epithelium with the normal squamous lining in this condition offers the possibility of decreasing the risk of degeneration to invasive adenocarcinoma. This study aimed to establish the feasibility of argon beam plasma coagulation (ABPC), in conjunction with control of gastroesophageal reflux, to restore the squamous

James P. Byrne; Gordon R. Armstrong; Stephen E. A. Attwood

1998-01-01

8

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

9

Argon plasma coagulation in the management of uncovered tracheal stent fracture  

PubMed Central

Endotracheal and endobronchial stenting, particularly with uncovered stents, can be complicated by stent fracture, granulation tissue formation, direct airway injury, and airway obstruction. While stent removal is possible, it can result in significant complications and long-term benefit is not guaranteed. Argon plasma coagulation can be employed to trim fractured stent fragments and remove granulation tissue simultaneously. In this manuscript, we report a case and describe our experience with using this technique.

Ching, Yiu-Hei; Geck, Robert D.; Andrews, Arthur D.; Rumbak, Mark J.; Camporesi, Enrico M.

2014-01-01

10

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

11

Treatment with argon plasma coagulation reduces recurrence after piecemeal resection of large sessile colonic polyps: A randomized trial and recommendations  

Microsoft Academic Search

Background: Recurrence is frequent after piecemeal snare resection of large sessile colorectal polyps. The aim of this study was to evaluate the safety and efficacy of argon plasma coagulation (APC) in preventing recurrence when applied to the edge and base of the polypectomy site after apparently complete piecemeal resection. Methods: Patients with large (>1.5 cm) sessile polyps removed by piecemeal

Jim C. Brooker; Brian P. Saunders; Syed G. Shah; Catherine J. Thapar; Noriko Suzuki; Christopher B. Williams

2002-01-01

12

Effective treatment of solitary rectal ulcer syndrome using argon plasma coagulation.  

PubMed

Solitary rectal ulcer syndrome (SRUS) is a chronic, multiform, non-cancerous disorder of the rectum, the final diagnosis of which is based upon histopathological criteria. This disorder is often accompanied by latent proctoptosis. We present a patient who (in 1996) was the first case in which argon plasma coagulation (APC) was used for SRUS treatment. In the years 2004-2005 the same patient underwent 15 APC sessions (at monthly intervals) obtaining full recovery from SRUS, although she had been treated unsuccessfully for 17 years prior to that. Six-year observation did not show any relapse. Local therapy with APC seems to be an important alternative in SRUS treatment without prolapse of the rectum and could become a basic method for bleeding treatment in SRUS. PMID:25276257

Waniczek, Dariusz; Rdes, Jerzy; Rudzki, Marek K; Piecuch, Jerzy; Rubicz, Nina; Arendt, Jerzy

2014-01-01

13

Effective treatment of solitary rectal ulcer syndrome using argon plasma coagulation  

PubMed Central

Solitary rectal ulcer syndrome (SRUS) is a chronic, multiform, non-cancerous disorder of the rectum, the final diagnosis of which is based upon histopathological criteria. This disorder is often accompanied by latent proctoptosis. We present a patient who (in 1996) was the first case in which argon plasma coagulation (APC) was used for SRUS treatment. In the years 2004–2005 the same patient underwent 15 APC sessions (at monthly intervals) obtaining full recovery from SRUS, although she had been treated unsuccessfully for 17 years prior to that. Six-year observation did not show any relapse. Local therapy with APC seems to be an important alternative in SRUS treatment without prolapse of the rectum and could become a basic method for bleeding treatment in SRUS. PMID:25276257

Waniczek, Dariusz; Rdes, Jerzy; Piecuch, Jerzy; Rubicz, Nina; Arendt, Jerzy

2014-01-01

14

Therapeutic effect of argon plasma coagulation on small malignant gastrointestinal tumors.  

PubMed

In endoscopy, argon plasma coagulation (APC) is a new principle of non-contact electrocoagulation and has proved to be a sufficient tool for palliative endoscopic treatment of gastrointestinal neoplasms, predominantly of the oesophagus and colorectum. In a study of 67 patients suffering from histologically confirmed and endosonographic T1-staged tumours of the gastrointestinum, 10 patients were selected for endoscopic APC treatment because of the impossibility of surgical therapy. Although the application was primarily of a palliative nature, in 9 of 10 cases of minor neoplasms, no further tumour could be detected in biopsies during the observation period (9.45 +/- 2.8 months). One patient was not cured locally. In none of the patients was any serious complication noticed during the outpatient follow-up. The effective results and lack of severe complications suggest this technique as an alternative therapy in selected patients with smaller gastrointestinal tumours. PMID:7538505

Sessler, M J; Becker, H D; Flesch, I; Grund, K E

1995-01-01

15

Eradication of Barrett’s mucosa with argon plasma coagulation and acid suppression: immediate and mid term results  

Microsoft Academic Search

Background—Intestinal metaplastic mucosa in Barrett’s oesophagus can be replaced by squamous epithelium after mucosal thermal ablation associated with acid suppression therapy.Aims—To assess whether restoration of squamous epithelium can be obtained after ablation of Barrett’s oesophagus using argon plasma coagulation (APC) associated with proton pump inhibitor (PPI) therapy.Methods—Thirty one patients with Barrett’s oesophagus received APC. Omeprazole (40 mg\\/day) was given from

J-L Van Laethem; M Cremer; M O Peny; M Delhaye; J Devière

1998-01-01

16

Clinical Outcomes of Argon Plasma Coagulation Therapy for Early Gastric Neoplasms  

PubMed Central

Background/Aims Argon plasma coagulation (APC) has some merits in the treatment of gastric neoplasms including a shorter operative time and fewer complications compared with endoscopic mucosal resection or endoscopic submucosal dissection. However, there are few reports on the outcomes of gastric neoplasms treated using APC. The aim of this study was to evaluate APC in the treatment of early gastric neoplasms in terms of clinical efficacy, safety, and local recurrence. Methods We enrolled 28 patients who received APC therapy at the Kyungpook National University Hospital between May 2007 and April 2013. Clinical outcomes were analyzed. Results The median follow-up period was 24.8 months (range, 2 to 78). Among the 28 lesions treated using the APC procedure, tumor recurrence was encountered in seven lesions (25.0%). Recurrence was found in 50% (5/10) of single APC cases and 11% (2/18) of rescue APC cases. The mean time to recurrence was 16.1 months (range, 2 to 78). There were no serious APC-related complications such as perforation, bleeding, or infection. Conclusions APC therapy can be a useful treatment with a favorable safety profile for patients with early gastric neoplasms. However, further studies are necessary to determine the long-term prognosis of patients undergoing this treatment.

Kim, Kyu Young; Yang, Hea Min; Lee, Yu Rim; Kang, Eun Jeong; Lee, Hyun Seok; Kim, Sung Kook

2015-01-01

17

Successful Treatment of Severe Spontaneous Periampullary Bleeding with Argon Plasma Coagulation  

PubMed Central

Periampullary bleeding is an uncommon cause of upper gastrointestinal (GI) hemorrhage, which is typically iatrogenic in origin occurring as the result of endoscopic intervention of the papilla. Spontaneous, non-iatrogenic periampullary bleeding is extraordinarily rare with only a few cases reported in the literature to date. Vascular malformations, including angiodysplasia and Dieulafoy’s lesions, have been implicated in several reports as the etiology but endoscopic intervention is often unsuccessful in achieving durable hemostasis with surgery being required for definitive management in many cases. Herein is reported the case of a 67-year-old male on anticoagulation for atrial fibrillation who presented with severe upper GI bleeding determined to be arising from underneath the hood of the major papilla. No distinct lesion was seen endoscopically but the presumed etiology was an unidentified vascular malformation. Successful treatment was achieved with argon plasma coagulation (APC) applied circumferentially around the papilla. No subsequent endoscopic or surgical intervention was required for durable hemostasis and the patient was able to resume anticoagulation shortly after the procedure. This is the first reported case of spontaneous periampullary bleeding successfully treated with APC. PMID:25237214

Abadir, Amir

2014-01-01

18

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

2012-09-01

19

Argon Plasma Coagulation Therapy Versus Topical Formalin for Intractable Rectal Bleeding and Anorectal Dysfunction After Radiation Therapy for Prostate Carcinoma  

SciTech Connect

Purpose: To evaluate and compare the effect of argon plasma coagulation (APC) and topical formalin for intractable rectal bleeding and anorectal dysfunction associated with chronic radiation proctitis. Methods and Materials: Thirty men (median age, 72 years; range, 49-87 years) with intractable rectal bleeding (defined as ?1× per week and/or requiring blood transfusions) after radiation therapy for prostate carcinoma were randomized to treatment with APC (n=17) or topical formalin (n=13). Each patient underwent evaluations of (1) anorectal symptoms (validated questionnaires, including modified Late Effects in Normal Tissues–Subjective, Objective, Management, and Analytic and visual analogue scales for rectal bleeding); (2) anorectal motor and sensory function (manometry and graded rectal balloon distension); and (3) anal sphincteric morphology (endoanal ultrasound) before and after the treatment endpoint (defined as reduction in rectal bleeding to 1× per month or better, reduction in visual analogue scales to ?25 mm, and no longer needing blood transfusions). Results: The treatment endpoint was achieved in 94% of the APC group and 100% of the topical formalin group after a median (range) of 2 (1-5) sessions of either treatment. After a follow-up duration of 111 (29-170) months, only 1 patient in each group needed further treatment. Reductions in rectal compliance and volumes of sensory perception occurred after APC, but no effect on anorectal symptoms other than rectal bleeding was observed. There were no differences between APC and topical formalin for anorectal symptoms and function, nor for anal sphincteric morphology. Conclusions: Argon plasma coagulation and topical formalin had comparable efficacy in the durable control of rectal bleeding associated with chronic radiation proctitis but had no beneficial effect on anorectal dysfunction.

Yeoh, Eric, E-mail: eric.yeoh@health.sa.gov.au [Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide (Australia); School of Medicine, University of Adelaide, Adelaide (Australia); Tam, William; Schoeman, Mark [School of Medicine, University of Adelaide, Adelaide (Australia); Department of Gastroenterology, Royal Adelaide Hospital, Adelaide (Australia); Moore, James; Thomas, Michelle [School of Medicine, University of Adelaide, Adelaide (Australia); Department of Colorectal Surgery, Royal Adelaide Hospital, Adelaide (Australia); Botten, Rochelle; Di Matteo, Addolorata [Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide (Australia)

2013-12-01

20

Sixteen-year follow-up of Barrett’s esophagus, endoscopically treated with argon plasma coagulation  

PubMed Central

Objective The thermal destruction of non-dysplastic Barrett’s esophagus (BE) and its replacement by squamous epithelium is an attractive, but unproven strategy to avoid further development of dysplasia or cancer. The goal of this study was to estimate the persistence of restoration of squamous epithelium and the risk of cancer in BE that was eradicated using argon plasma coagulation (APC) in the absence of high-grade dysplasia, 16 years after its application. Design We followed 32 patients with BE who underwent eradication of metaplastic epithelium using APC, up to 16 years later. Results At the end of the initial treatment, 25 of 32 patients (78%) had complete endoscopic eradication, there was partial squamous re-epithelialization in four patients (13%) and it was absent in three patients (9%). We observed buried metaplastic glands under new squamous epithelium in 6 of the 25 patients who had complete endoscopic eradication. At follow-up, sustained complete endoscopic eradication was observed in 16 of 32 patients (50%), partial eradication in 11 of 32 patients (35%); there were two patients (6%) lost to follow-up and three patients (9%) developed esophageal adenocarcinoma. Two of the latest cases arose from the buried glands under neosquamous epithelium after complete eradication and one arose from a small remaining Barrett’s segment. Conclusions We observed long-term re-epithelialization in the majority of patients who had previously had complete eradication of Barrett’s esophagus. This did not provide protection against cancer development, as the incidence of cancers arising from buried glands or from residual Barrett’s esophagus was similar to that observed in patients undergoing no specific treatment. PMID:25360314

Milashka, Mariana; Calomme, Annabelle; Van Laethem, Jean Luc; Blero, Daniel; Eisendrath, Pierre; Le Moine, Olivier

2014-01-01

21

The tissue effect of argon-plasma coagulation with prior submucosal injection (Hybrid-APC) versus standard APC: A randomized ex-vivo study  

PubMed Central

Background Thermal ablation for Barrett’s oesophagus has widely been established in gastrointestinal endoscopy during the last decade. The mainly used methods of radiofrequency ablation (RFA) and argon-plasma coagulation (APC) carry a relevant risk of stricture formation of up to 5–15%. Newer ablation techniques that are able to overcome this disadvantage would therefore be desirable. The aim of the present study was to compare the depth of tissue injury of the new method of Hybrid-APC versus standard APC within a randomized study in a porcine oesophagus model. Methods Using a total of eight explanted pig oesophagi, 48 oesophageal areas were ablated either by standard or Hybrid-APC (APC with prior submucosal fluid injection) using power settings of 50 and 70?W. The depth of tissue injury to the oesophageal wall was analysed macroscopically and histopathologically. Results Using 50?W, mean coagulation depth was 937?±?469?µm during standard APC, and 477?±?271?µm during Hybrid-APC (p?=?0.064). Using 70?W, coagulation depth was 1096?±?320?µm (standard APC) and 468?±?136?µm (Hybrid-APC; p?=?0.003). During all settings, damage to the muscularis mucosae was observed. Using standard APC, damage to the submucosal layer was observed in 4/6 (50?W) and 6/6 cases (70?W). During Hybrid-APC, coagulation of the submucosal layer occurred in 2/6 (50?W) and 1/6 cases (70?W). The proper muscle layer was only damaged during conventional APC (50?W: 1/6; 70?W: 3/6). Limitations Ex-vivo animal study with limited number of cases. Conclusions Hybrid-APC reduces coagulation depth by half in comparison with standard APC, with no thermal injury to the proper muscle layer. It may therefore lead to a lower rate of stricture formation during clinical application. PMID:25360316

Neugebauer, Alexander; Scharpf, Marcus; Braun, Kirsten; May, Andrea; Ell, Christian; Fend, Falko; Enderle, Markus D

2014-01-01

22

Comparison of Hemostatic Efficacy of Argon Plasma Coagulation with and without Distilled Water Injection in Treating High-Risk Bleeding Ulcers  

PubMed Central

Background. Argon plasma coagulation (APC) is useful to treat upper gastrointestinal bleeding, but its hemostatic efficacy has received little attention. Aims. This investigation attempted to determine whether additional endoscopic injection before APC could improve hemostatic efficacy in treating high-risk bleeding ulcers. Methods. From January 2007 to April 2011, adult patients with high-risk bleeding ulcers were included. This investigation compared APC plus distilled water injection (combined group) to APC alone for treating high-risk bleeding ulcers. Outcomes were assessed based on initial hemostasis, surgery, blood transfusion, hospital stay, rebleeding, and mortality at 30 days posttreatment. Results. Totally 120 selected patients were analyzed. Initial hemostasis was accomplished in 59 patients treated with combined therapy and 57 patients treated with APC alone. No significant differences were noted between these groups in recurred bleeding, emergency surgery, 30-day mortality, hospital stay, or transfusion requirements. Comparing the combined end point of mortality plus the failure of initial hemostasis, rebleeding, and the need for surgery revealed an advantage for the combined group (P = 0.040). Conclusions. Endoscopic therapy with APC plus distilled water injection was no more effective than APC alone in treating high-risk bleeding ulcers, whereas combined therapy was potentially superior for patients with poor overall outcomes. PMID:25243138

Hsu, Ping-I; Chan, Hoi-Hung; Wang, Kai-Ming; Tsai, Wei-Lun; Yu, Hsien-Chung; Tsay, Feng-Woei

2014-01-01

23

Hemostasis after partial hepatectomy using argon beam coagulation and a concentrated albumin  

Microsoft Academic Search

Background: The argon beam coagulator (ABC) is frequently used to control bleeding on parenchymatous organs during surgery. The purpose of this study was to assess whether it improves the efficacy of hemostasis of using the argon beam coagulation with a concentrated human albumin at partial hepatectomy. Methods: Thirty-two domestic swine were randomized and treated with either conventional argon beam coagulation

Hua Xie; Ronald F. Wolf; John Petty; Allen Burke; Jeffery S. Teach; Kenton W. Gregory; Scott A. Prahl

24

Coagulation Factor XIIIa Substrates in Human Plasma  

PubMed Central

Coagulation factor XIII (FXIII) is a transglutaminase with a well defined role in the final stages of blood coagulation. Active FXIII (FXIIIa) catalyzes the formation of ?-(?-glutamyl)lysine isopeptide bonds between specific Gln and Lys residues. The primary physiological outcome of this catalytic activity is stabilization of the fibrin clot during coagulation. The stabilization is achieved through the introduction of cross-links between fibrin monomers and through cross-linking of proteins with anti-fibrinolytic activity to fibrin. FXIIIa additionally cross-links several proteins with other functionalities to the clot. Cross-linking of proteins to the clot is generally believed to modify clot characteristics such as proteolytic susceptibility and hereby affect the outcome of tissue damage. In the present study, we use a proteomic approach in combination with transglutaminase-specific labeling to identify FXIIIa plasma protein substrates and their reactive residues. The results revealed a total of 147 FXIIIa substrates, of which 132 have not previously been described. We confirm that 48 of the FXIIIa substrates were indeed incorporated into the insoluble fibrin clot during the coagulation of plasma. The identified substrates are involved in, among other activities, complement activation, coagulation, inflammatory and immune responses, and extracellular matrix organization. PMID:24443567

Nikolajsen, Camilla Lund; Dyrlund, Thomas F.; Poulsen, Ebbe Toftgaard; Enghild, Jan J.; Scavenius, Carsten

2014-01-01

25

Coagulation of dust particles in plasma  

NASA Astrophysics Data System (ADS)

Dusty plasmas are found in numerous astrophysical environments. Coagulation of the charged dust changes their interaction with the plasma and affects the subsequent dynamics and evolution of the system. The complex microphysics underlying these processes depends on parameters specific to the ambient environment and the grains themselves. Different charging processes can yield populations of grains which are all charged negatively or charged with opposite polarities. The charge on an aggregate distributes itself over the aggregate's surface which can be approximated theoretically by assuming a multipole distribution. The dipole-dipole charge interactions between aggregates lead to rotations of the colliding grains. Other grain properties also influence the coagulation process, such as the monomer shape or the presence of magnetic material. The morphology of the resultant aggregates affects subsequent coagulation. Porous fluffy aggregates are more strongly coupled to the gas, leading to reduced collisional velocities, and greater collisional cross sections. An overview of the numerical and experimental methods used to study dust coagulation at CASPER will be given.

Matthews, Lorin; Carmona-Reyes, Jorge; Land, Victor; Ma, Qianyu; Deline, Kristen; Perry, Jonathan; Doyle, Brandon; Hyde, Truell

2011-10-01

26

Axisymmetric Argon-Plasma-Jet Behaviors in Argon Surrounding Based on a Lattice Boltzmann Computational Method  

E-print Network

Axisymmetric Argon-Plasma-Jet Behaviors in Argon Surrounding Based on a Lattice Boltzmann, in one side, as former studies, E. Pfender et al. [2] have performed a simulation of Argon plasma, and surrounding atmosphere). In a comparative study, D.-Y. Xu et al. [8] have shown that using argon instead

27

Total laparoscopic radical hysterectomy with pelvic lymphadenectomy using the argon-beam coagulator: pilot data and comparison to laparotomy  

Microsoft Academic Search

ObjectivesThe aim of this study was to describe the feasibility and outcome of total laparoscopic radical hysterectomy with pelvic lymphadenectomy for stage I cervical cancer using the argon-beam coagulator.

Nadeem R Abu-Rustum; Mary L Gemignani; Kathleen Moore; Yukio Sonoda; Ennapadam Venkatraman; Carol Brown; Elizabeth Poynor; Dennis S Chi; Richard R Barakat

2003-01-01

28

Contact activation of blood-plasma coagulation  

NASA Astrophysics Data System (ADS)

Surface engineering of biomaterials with improved hemocompatibility is an imperative, given the widespread global need for cardiovascular devices. Research summarized in this dissertation focuses on contact activation of FXII in buffer and blood plasma frequently referred to as autoactivation. The extant theory of contact activation imparts FXII autoactivation ability to negatively charged, hydrophilic surfaces. According to this theory, contact activation of plasma involves assembly of proteins comprising an "activation complex" on activating surfaces mediated by specific chemical interactions between complex proteins and the surface. This work has made key discoveries that significantly improve our core understanding of contact activation and unravel the existing paradigm of plasma coagulation. It is shown herein that contact activation of blood factor XII (FXII, Hageman factor) in neat-buffer solution exhibits a parabolic profile when scaled as a function of silanized-glass-particle activator surface energy (measured as advancing water adhesion tension t°a=g° Iv costheta in dyne/cm, where g°Iv is water interfacial tension in dyne/cm and theta is the advancing contact angle). Nearly equal activation is observed at the extremes of activator water-wetting properties --36 < t°a < 72 dyne/cm (O° ? theta < 120°), falling sharply through a broad minimum within the 20 < t°a < 40 dyne/cm (55° < theta < 75°). Furthermore, contact activation of FXII in buffer solution produces an ensemble of protein fragments exhibiting either procoagulant properties in plasma (proteolysis of blood factor XI or prekallikrein), amidolytic properties (cleavage of s-2302 chromogen), or the ability to suppress autoactivation through currently unknown biochemistry. The relative proportions of these fragments depend on activator surface chemistry/energy. We have also discovered that contact activation is moderated by adsorption of plasma proteins unrelated to coagulation through an "adsorption-dilution" effect that blocks FXII contact with hydrophobic activator surfaces. The adsorption-dilution effect explains the apparent specificity for hydrophilic activators pursued by earlier investigators. Finally a comparison of FXII autoactivation in buffer, serum, protein cocktail, and plasma solutions is shown herein. Activation of blood plasma coagulation in vitro by contact with material surfaces is demonstrably dependent on plasma-volume-to-activator-surface-area ratio. However, activation of factor XII dissolved in buffer, protein cocktail, heat-denatured serum, and FXI deficient plasma does not exhibit activator surface-area dependence. Instead, a highly-variable burst of procoagulant-enzyme yield is measured that exhibits no measurable kinetics, sensitivity to mixing, or solution-temperature dependence. Thus, FXII activation in both buffer and protein-containing solutions does not exhibit characteristics of a biochemical reaction but rather appears to be a "mechanochemical" reaction induced by FXII molecule interactions with hydrophilic activator particles that do not formally adsorb blood proteins from solution. Results strongly suggest that activator surface-area dependence observed in contact activation of plasma coagulation does not solely arise at the FXII activation step of the intrinsic pathway.

Golas, Avantika

29

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

30

Merging of high speed argon plasma jets  

SciTech Connect

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. [HyperV Technologies Corp., Chantilly, Virginia 22180 (United States); Elton, R. [University of Maryland, College Park, Maryland 20742 (United States)

2013-01-15

31

[Experimental study of the effect of the Argon Beam Coagulator on organic tissues from the viewpoint of surgical utilization].  

PubMed

The Argon Beam Coagulator has gained his space in surgery thanks to its operative characteristics, that are very useful in sealing the bleeding parenchymal tissue with minimal injury to the surroundings. The aim of the present study is that of evaluate the physical properties of the instrument in its coagulation action. The experimental study with the Birtcher 6000 Argon Beam Coagulator has been designed to measure the top temperature that develops right where the Argon beam meets the tissue, while operating. Using a laser guided telethermometer, the searching of that temperature was uneasy right on the operatory field because of the unwilling movements of the operator hand and those of the patient himself. Therefore a similar protocol was made on a piece of meat coming from the butcher. At the longest application of the beam coagulation on the same point the developed temperature was never higher than 100 degrees C whilst a complete coagulation effects. The advantage of the Argon Beam coagulation are therefore to seal the diffuse bleeding without injury to this adjacent tissues, never exposed to a temperature higher than that of boiling water. The advantages are also evident in comparison with the more usual spray electrosurgery that is instead characterized by a wide carbonisation also with this spray option. PMID:15283389

Falbo, B; Vene, M; Visini, R; Grottola, T; Di Paolo, S; Picardi, N

2004-01-01

32

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

33

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

34

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

35

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...

36

Modeling of an argon cascaded arc plasma by ANSYS FLUENT  

NASA Astrophysics Data System (ADS)

In this work, an argon cascaded arc plasma is simulated by the business software ANSYS FLUENT. In fact, thus plasma is a high temperature arc (plasma window) with an average temperature of 12000 °C, which can be used as a medium between high pressure and vacuum mainly due to its characteristics of high temperature. According to the simulating results, the temperature can reach as high as 11500 °C which is in great agreement with that of other reports about plasma window.

Wei, Guodong; Qi, Xin; Yang, Lei

2014-04-01

37

Treatment of pitch in argon/hydrogen plasmas  

SciTech Connect

This paper reports on pitch-like vacuum-distilled residue from the CANMET coprocessing process that was treated in a stationary particle reactor with argon/hydrogen plasmas. The production of light, unsaturated hydrocarbons was optimized as a function of the average plasma temperature, composition, and residence time. The unconverted residue was characterized in terms of its elemental and mineralogical content. In pure argon plasma, the conversion to acetylene was about 14% and did not vary appreciably with temperature; other hydrocarbons were detected only in trace quantities. In argon/hydrogen plasmas the maximum conversion to acetylene and ethylene (25%) was attained between 2900 and 3400 K. Large quantities of soot were produced, but no liquid hydrocarbons were detected. Sulfur was fixed in the unconverted residue by the reduction of calcium sulfate to calcium sulfide.

Dlugogorski, B.Z.; Berk, D.; Munz, R.J. (Dept. of Chemical Engineering, McGill Univ., Montreal, Quebec H3A 2A7 (CA))

1992-03-01

38

Properties of radio-frequency heated argon confined uranium plasmas  

NASA Technical Reports Server (NTRS)

Pure uranium hexafluoride (UF6) was injected into an argon confined, steady state, rf-heated plasma within a fused silica peripheral wall test chamber. Exploratory tests conducted using an 80 kW rf facility and different test chamber flow configurations permitted selection of the configuration demonstrating the best confinement characteristics and minimum uranium compound wall coating. The overall test results demonstrated applicable flow schemes and associated diagnostic techniques were developed for the fluid mechanical confinement and characterization of uranium within an rf plasma discharge when pure UF6 is injected for long test times into an argon-confined, high-temperature, high-pressure, rf-heated plasma.

1976-01-01

39

Effect of argon addition on plasma parameters and dust charging in hydrogen plasma  

SciTech Connect

Experimental results on effect of adding argon gas to hydrogen plasma in a multi-cusp dusty plasma device are reported. Addition of argon modifies plasma density, electron temperature, degree of hydrogen dissociation, dust current as well as dust charge. From the dust charging profile, it is observed that the dust current and dust charge decrease significantly up to 40% addition of argon flow rate in hydrogen plasma. But beyond 40% of argon flow rate, the changes in dust current and dust charge are insignificant. Results show that the addition of argon to hydrogen plasma in a dusty plasma device can be used as a tool to control the dust charging in a low pressure dusty plasma.

Kakati, B., E-mail: bharatkakati15@gmail.com; Kausik, S. S.; Saikia, B. K. [Centre of Plasma Physics-Institute for Plasma Research, Nazirakhat, Sonapur, Kamrup 782402, Assam (India); Bandyopadhyay, M.; Saxena, Y. C. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

2014-10-28

40

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

41

Radiative energy loss in a non-equilibrium argon plasma  

Microsoft Academic Search

The total radiative loss in atmospheric argon plasmas is calculated allowing for deviations from local Saha equilibrium LSE. The authors have taken into account non-equilibrium excited state populations using numerical and analytical collisional-radiative models. Simple expressions for the different radiation loss mechanisms are given in terms of the electron density, electron temperature and ionization degree. These quantities together with the

D. A. Benoy; Mullen van der JJAM; D. C. Schram

1993-01-01

42

Supersonic Argon Flow In An Arc Plasma Source  

SciTech Connect

The plasma properties inside a D.C. arc-jet operating with argon is analysed by means of a continuum description taking into account non equilibrium ionization processes and dissipative effects. The relaxation of the different physical processes inside the nozzle and the evolution of the Mach number are aanalysed.

Izrar, B.; Dudeck, M. [Laboratoire d'Aerothermique, 1C avenue de la Recherche Scientifique, 45071 Orleans cedex (France); Andre, P. [Laboratoire des Arc Electriques et des Plasmas Thermiques, LAEPT, Universite Blaise Pascal, 24 av. des landais, 63177 Aubiere cedex (France); Elchinger, M. F.; Aubreton, J. [Institut des Procedes Appliques aux Materiaux, Faculte des sciences de Limoges, 123 avenue Albert Thomas, 87060 Limoges cedex (France)

2006-01-15

43

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

44

Equation of state of partially ionized argon plasma  

SciTech Connect

The ionization degree, Hugoniots, and equation of state of partially ionized argon plasma were calculated by using self-consistent fluid variational theory for temperature of 6-50 kK and density of 0.05-4.0 g/cm{sup 3}. The corrections of lowering of ionization energy of fluid argon caused by the interactions among all particles of Ar, Ar{sup +}, Ar{sup 2+}, and e have been taken into consideration in terms of the correlation contributions to the chemical potential which is determined self-consistently by the free energy function. The initial density effects of gas argon under shock compression have been discussed. Comparison is performed with available shock-wave experiments and other theoretical calculations.

Chen, Q. F.; Zheng, J.; Gu, Y. J.; Chen, Y. L.; Cai, L. C.

2011-11-15

45

Flush-mounted probe diagnostics for argon glow discharge plasma.  

PubMed

A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on. PMID:25273724

Xu, Liang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi; Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang

2014-09-01

46

Flush-mounted probe diagnostics for argon glow discharge plasma  

SciTech Connect

A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on.

Xu, Liang, E-mail: xld02345@mail.ustc.edu.cn; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang [Science and Technology on Space Physics Laboratory, Beijing 100076 (China)

2014-09-15

47

Spectra simulation of the argon plasma  

Microsoft Academic Search

In this work, a simulation calculation scheme based on a collisional radiation model and employing detailed energy levels was developed under the framework of corona approximation for low-density plasmas. Atomic data such as energy levels, radiative transition rates, Auger rates, collision excitation and ionization cross sections needed for the simulation were calculated by using the Flexible Atomic Code. In this

Z. Geng; K. Yao; Y. Zou

2011-01-01

48

Langmuir Probe Measurements of an Expanding Argon Plasma  

NASA Astrophysics Data System (ADS)

In this work, we studied the effects of the discharge current, gas flow rate and vessel pressure on the electron temperature and density of Ar plasma by Langmuir probe measurement. The argon plasma was created by a one-cathode arc source. The experimental results show that with increasing discharge current and gas flow rate, the electron temperature and density increase. It is found that when the discharge current is 70 A, 90 A and 110 A at an argon flow rate of 2000 sccm, the electron densities at about 0.186 m distance from the nozzle are 13.00×1018 m?3, 14.04×1018 m?3 and 15.62×1018 m?3, and the electron temperatures are 0.38 eV, 0.58 eV and 0.71 eV, respectively. The positive I-V characteristic is explained.

Cao, Xiaogang; Xia, Yuxi; Chen, Bingzhou; Tian, Shuping; Wang, Chunling; Yang, Dangxiao; Xue, Xiaoyan; Zhang, Weiwei; Wang, Jianqiang; Gou, Fujun; Zhu, Zichuan; Ou, Wei; Chen, Shunli

2015-01-01

49

Numerical Modeling of an RF Argon-Silane Plasma with Dust Particle Nucleation and Growth  

NASA Astrophysics Data System (ADS)

We have developed a 1-D numerical model of an RF argon-silane plasma in which dust particles nucleate and grow. This model self-consistently couples a plasma module, a chemistry module and an aerosol module. The plasma module solves population balance equations for electrons and ions, the electron energy equation under the assumption of a Maxwellian velocity distribution, and Poisson's equation for the electric field. The chemistry module treats silane dissociation and reactions of silicon hydrides containing up to two silicon atoms. The aerosol module uses a sectional method to model particle size and charge distributions. The nucleation rate is equated to the rates of formation of anions containing two Si atoms, and a heterogeneous reaction model is used to model particle surface growth. Aerosol effects considered include particle charging, coagulation, and particle transport by neutral drag, ion drag, electric force, gravity and Brownian diffusion. Simulation results are shown for the case of a 13.56 MHz plasma at a pressure of 13 Pa and applied RF voltage of 100 V (amplitude), with flow through a showerhead electrode. These results show the strong coupling between the plasma and the spatiotemporal evolution of the nanoparticle cloud.

Girshick, Steven; Agarwal, Pulkit

2012-10-01

50

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

51

Laser induced fluorescence in a pulsed argon plasma Earl Scime,a)  

E-print Network

Laser induced fluorescence in a pulsed argon plasma Earl Scime,a) Costel Biloiu, Christopher fluorescence (LIF) technique for pulsed argon plasmas is described. A low power, tunable diode laser pumps detection, i.e., using a lock-in amplifier. Pulsed plasmas present the additional challenge of requiring

Choueiri, Edgar

52

Fluid simulation of a pulsed-power inductively coupled argon plasma D. P. Lymberopoulos  

E-print Network

Fluid simulation of a pulsed-power inductively coupled argon plasma D. P. Lymberopoulos Applied to investigate the spatiotemporal dynamics of a pulsed-power inductively coupled argon plasma at 10 m on the sheath thickness which is a complicated function of time in the pulsed plasma. For a constant time

Economou, Demetre J.

53

Plasma core reactor simulations using RF uranium seeded argon discharges  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted using the United Technologies Research Center (UTRC) 80 kW and 1.2 MW RF induction heater systems to aid in developing the technology necessary for designing a self-critical fissioning uranium plasma core reactor (PCR). A nonfissioning, steady-state RF-heated argon plasma seeded with pure uranium hexafluoride (UF6) was used. An overall objective was to achieve maximum confinement of uranium vapor within the plasma while simultaneously minimizing the uranium compound wall deposition. Exploratory tests were conducted using the 80 kW RF induction heater with the test chamber at approximately atmospheric pressure and discharge power levels on the order of 10 kW. Four different test chamber flow configurations were tested to permit selection of the configuration offering the best confinement characteristics for subsequent tests at higher pressure and power in the 1.2 MW RF induction heater facility.

Roman, W. C.

1975-01-01

54

Plasma core reactor simulations using RF uranium seeded argon discharges  

NASA Technical Reports Server (NTRS)

Experimental results are described in which pure uranium hexafluoride was injected into an argon-confined, steady-state, RF-heated plasma to investigate characteristics of plasma core nuclear reactors. The 80 kW (13.56 MHz) and 1.2 MW (5.51 MHz) rf induction heater facilities were used to determine a test chamber flow scheme which offered best uranium confinement with minimum wall coating. The cylindrical fused-silica test chamber walls were 5.7-cm-ID by 10-cm-long. Test conditions included RF powers of 2-85 kW, chamber pressures of 1-12 atm, and uranium hexafluoride mass-flow rates of 0.005-0.13 g/s. Successful techniques were developed for fluid-mechanical confinement of RF-heated plasmas with pure uranium hexafluoride injection.

Roman, W. C.

1976-01-01

55

Concerning Apparent Similarity of Structures of Fluoropolymer Surfaces Exposed to an Argon Plasma or Argon Ion Beam  

NASA Technical Reports Server (NTRS)

X-ray photoelectron spectroscopy (XPS) C(sub 1s) spectra of fluoropolymers exposed to either an argon plasma or argon ion beam show remarkable similarity, implying that the surface-modification reactions for these two processes likely proceed through comparable mechanisms, revolving predominantly ion-surface interactions. The importance of working with a monochromatized x-ray source for XPS analysis of the surface-modified fluoropolymers is once again emphasized.

Golub, Morton A.; Covington, M. Alan (Technical Monitor)

1995-01-01

56

In situ X-ray Photoemission Spectroscopy Analysis of Aromatic Polyester Surface Treated with Argon Plasma  

NASA Astrophysics Data System (ADS)

Effects of surface modification treatment by argon plasma processing of two types of aromatic polyester, poly(ethylene terephthalate) (PET) and poly(oxybenzonate-co-oxynaphthoate) (POCO), were investigated. This paper presents a description of our experiment and a discussion of the surface modification mechanism, which uses a simple and inexpensive procedure to conduct analysis without breaking vacuum after plasma processing. In situ analysis of the chemical composition of a polymer surface was attempted without exposing the sample to air after argon plasma processing. In particular, the respective actions of each active species were investigated for electrons and ions in argon plasma. Electrons and ions in argon plasma break some polymer bonds. Specifically, ester groups are broken and oxygen atoms are kicked out in PET and POCO. No oxygen functional group is formed after argon plasma processing, but such groups are formed if the sample is exposed to air.

Narushima, Kazuo; Okamoto, Nanami

2013-10-01

57

Detection of ozone in a MHz argon plasma bullet jet  

NASA Astrophysics Data System (ADS)

This study for the first time confirms the presence of plasma bullets in a MHz argon atmospheric pressure plasma jet. Bullet characteristics are investigated by phase-resolved optical emission measurements. Regarding the jet's reactive component output, its ozone production rates are investigated by two independent diagnostic techniques yielding complementary results. The first method—UV-absorption spectroscopy in the Hartley band—determines space-resolved distribution of the ozone concentration in the jet effluent. The second method—quantum cascade laser-absorption spectroscopy in the mid-infrared spectral region—yields high sensitivity results of the average ozone concentration in a multipass cell, in which the effluent is directed. The results of both diagnostic techniques show excellent agreement.

Reuter, S.; Winter, J.; Iseni, S.; Peters, S.; Schmidt-Bleker, A.; Dünnbier, M.; Schäfer, J.; Foest, R.; Weltmann, K.-D.

2012-06-01

58

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

59

Mesures du dplacement de la raie 703 nm de l'argon : application la dtermination de la densit lectronique dans un plasma d'argon  

E-print Network

527 Mesures du déplacement de la raie 703 nm de l'argon : application à la détermination de la densité électronique dans un plasma d'argon J. M. Badie, E. Billou et G. Vallbona Institut de Science et déplacement de la raie 703 nm de l'argon neutre en fonction de la densité électronique dans un arc d'argon

Paris-Sud XI, Université de

60

Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure  

Microsoft Academic Search

This work presents a few preliminary results from a collisional-radiative (CR) model intended to describe an argon microwave (2.45 GHz) plasma at atmospheric pressure. This model aims to investigate the influence of dissociative recombination products on the Saha-Boltzmann plasma equilibrium. The model is tested through comparison with experimental results obtained in an argon plasma column generated by a traveling electromagnetic

Abel Sainz; Joelle Margot; Maria Carmen Garcia; Maria Dolores Calzada

2004-01-01

61

Surface treatment of para-aramid fiber by argon dielectric barrier discharge plasma at atmospheric pressure  

NASA Astrophysics Data System (ADS)

This paper is focused on influence of argon dielectric barrier discharge (DBD) plasma on the adhesive performance and wettability of para-aramid fibers and three parameters including treated power, exposure time and argon flux were detected. The interfacial shear strength (IFSS) was greatly increased by 28% with 300 W, 60 s, 2 L min-1 argon flux plasma treatment. The content of oxygen atom and oxygen-containing polar functional groups were enhanced after the argon plasma treated, so as the surface roughness, which contributed to the improvement of surface wettability and the decrease of contact angle with water. However, long-time exposure, exorbitant power or overlarge argon flux could partly destroy the prior effects of the treatment and damage the mechanical properties of fibers to some degree.

Gu, Ruxi; Yu, Junrong; Hu, Chengcheng; Chen, Lei; Zhu, Jing; Hu, Zuming

2012-10-01

62

Electrostatic waves in plasma: the case of an expanding microwave plasma sustained in argon  

NASA Astrophysics Data System (ADS)

This work is devoted to the study of the electrostatic wave dispersion in plasma. Investigations are focused on waves with angular frequency ranging between the ion and the electron angular resonance frequency. The dispersion equation is resolved by means of a Fourier transform spectral method in the case of theoretical Maxwell–Boltzmann electron energy distribution functions (EEDFs), and in the case of experimental EEDFs measured by means of a Langmuir probe in microwave expanding plasma sustained in argon. The results show the change of the dispersion curve with the plasma parameters and the role of electrons and ions in the shape of the dispersion curve.

Jauberteau, J. L.; Jauberteau, I.

2014-12-01

63

Mechanism of Blood Coagulation by Nonthermal Atmospheric Pressure Dielectric Barrier Discharge Plasma  

Microsoft Academic Search

Mechanisms of blood coagulation by direct contact of nonthermal atmospheric pressure dielectric barrier discharge (DBD) plasma are investigated. This paper shows that no significant changes occur in the pH or Ca2+ concentration of blood during discharge treatment. Thermal effects and electric field effects are also shown to be negligible. Investigating the hypothesis that the discharge treatment acts directly on blood

Sameer U. Kalghatgi; Gregory Fridman; Moogega Cooper; Gayathri Nagaraj; Marie Peddinghaus; Manjula Balasubramanian; Victor N. Vasilets; Alexander F. Gutsol; Alexander Fridman; Gary Friedman

2007-01-01

64

Atmospheric Pressure Humid Argon DBD Plasma for the Application of Sterilization -Measurement and Simulation of Hydrogen, Oxygen, and Hydrogen  

E-print Network

Atmospheric Pressure Humid Argon DBD Plasma for the Application of Sterilization - Measurement peroxide have been measured downstream of an atmospheric pressure humid argon dielectric barrier discharge. The results of experiments on the use of post-discharge effluent gas of humid argon plasma for sterilization

Paris-Sud XI, Université de

65

Measurements and modeling of ion and neutral distribution functions in a partially ionized magnetically confined argon plasma  

E-print Network

magnetically confined argon plasma C. A. Michael,a) J. Howard, and B. D. Blackwell PRL, RSPhysSE, Australian is studied in low field ( 0.15 T) rf heated argon discharges of the H-1 Heliac S. M. Hamberger, B. D) argon discharges of the H-1 Heliac,3 where the plasma is produced and the electrons are heated

Howard, John

66

Particle modeling of non-collisional heating in inductively coupled argon plasmas  

Microsoft Academic Search

The effect of non-collisional heating on inductively coupled argon plasma is examined using the particle modeling. The effect is clarified by comparing the plasma densities obtained using two types of plasma current; one is the warm current directly sampled from the velocities of electrons and the other is the cold current given by Ohm's law. The calculation is performed for

H. Takekida; K. Nanbu

2006-01-01

67

Research on Surface Modification of Polytetrafluoroethylene Coupled With Argon Dielectric Barrier Discharge Plasma Jet Characteristics  

Microsoft Academic Search

An argon dielectric barrier discharge (DBD) atmospheric-pressure plasma jet (APPJ) is designed and employed for surface modification of polytetrafluoroethylene (PTFE). The plasma diagnostics and dielectric surface analysis are coupled together to investigate the mechanisms of plasma modification. The discharge power is obtained by Lissajous figure, and electron excitation temperature (EET) is measured through an optical emission spectrum and calculated by

Xian-Jun Shao; Guan-Jun Zhang; Jiang-Yang Zhan; Gui-Min Xu

2011-01-01

68

Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge  

SciTech Connect

An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O{sub 2}/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion, Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China) and School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 137-701 (Korea, Republic of)

2011-10-15

69

Characteristics of a non-Maxwellian electron energy distribution in a low-pressure argon plasma  

NASA Astrophysics Data System (ADS)

The generality of the non-Maxwellian electron energy distribution function (EEDF) is demonstrated by using optical emission spectroscopy (OES) and Langmuir probe measurements in inductively- and capacitively-coupled low-pressure argon plasmas to analyze the shape factor of the EEDF. To measure the shape factor of the EEDF, we propose a corona — equilibrium (CE) — based analysis model operating at low density, which uses the line intensity ratio of the Ar I to the Ar II emission lines. The Ar I line is chosen to represent the relatively low-energy state, and the Ar II line is chosen to represent the high-energy state. Thus, an analysis of the shape factor is equivalent to monitoring the variation in the high-energy electron fraction represented in the tail of the EEDF. Results show a depleted tail for the Maxwellian distribution in most of the low-density argon plasmas. The analysis reveals that the generation and the stepwise ionization of metastable argon atoms by inelastic collisions with high-energy (˜ 10 eV) electrons are dominant processes of argon plasma generation and cause serious high-energy electron loss in a low-density system compared to the loss in an ideal Maxwellian plasma. The existence of argon metastable states is inevitable; thus, the general shape of the electron energy distribution in low-pressure argon plasmas is non-Maxwellian.

Park, Seolhye; Choe, Jae-Myung; Roh, Hyun-Joon; Kim, Gon-Ho

2014-06-01

70

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

Microsoft Academic Search

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 H2O-Ar mixture flow rate of 1.7 standard liter per

Nimisha Srivastava; Chuji Wang

2011-01-01

71

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

72

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

73

Non-local thermodynamic equilibrium effects on isentropic coefficient in argon and helium thermal plasmas  

SciTech Connect

In the present work, two cases of thermal plasma have been considered; the ground state plasma in which all the atoms and ions are assumed to be in the ground state and the excited state plasma in which atoms and ions are distributed over various possible excited states. The variation of Z?, frozen isentropic coefficient and the isentropic coefficient with degree of ionization and non-equilibrium parameter ?(= T{sub e}/T{sub h}) has been investigated for the ground and excited state helium and argon plasmas at pressures 1?atm, 10?atm, and 100?atm in the temperature range from 6000?K to 60?000?K. For a given value of non-equilibrium parameter, the relationship of Z? with degree of ionization does not show any dependence on electronically excited states in helium plasma whereas in case of argon plasma this dependence is not appreciable till degree of ionization approaches 2. The minima of frozen isentropic coefficient shifts toward lower temperature with increase of non-equilibrium parameter for both the helium and argon plasmas. The lowering of non-equilibrium parameter decreases the frozen isentropic coefficient more emphatically in helium plasma at high pressures in comparison to argon plasma. The increase of pressure slightly reduces the ionization range over which isentropic coefficient almost remains constant and it does not affect appreciably the dependence of isentropic coefficient on non-equilibrium parameter.

Sharma, Rohit [Satyam Institute of Engineering and Technology, Amritsar 143107 (India)] [Satyam Institute of Engineering and Technology, Amritsar 143107 (India); Singh, Kuldip [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)] [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

2014-03-15

74

MESURE DE LA TEMPRATURE DES PARTICULES LOURDES DANS UN JET DE PLASMA D'ARGON SOUS PRESSION (*)  

E-print Network

1187 MESURE DE LA TEMP�RATURE DES PARTICULES LOURDES DANS UN JET DE PLASMA D'ARGON SOUS PRESSION mesurer la tem- pérature atomique T0 d'un plasma d'argon faiblement ionisé (degré d'ionisation ~ 10-4, Ne ionized argon plasma (ionisation degree ~ 10-4, Ne ~ 1014 cm-3, Te ~ 6 000 K) for pressures ranging from 1

Boyer, Edmond

75

Inhibition of vascular permeability by antisense-mediated inhibition of plasma kallikrein and coagulation factor 12.  

PubMed

Hereditary angioedema (HAE) is a rare disorder characterized by recurrent, acute, and painful episodes of swelling involving multiple tissues. Deficiency or malfunction of the serine protease inhibitor C1 esterase inhibitor (C1-INH) results in HAE types 1 and 2, respectively, whereas mutations in coagulation factor 12 (f12) have been associated with HAE type 3. C1-INH is the primary inhibitor of multiple plasma cascade pathways known to be altered in HAE patients, including the complement, fibrinolytic, coagulation, and kinin-kallikrein pathways. We have selectively inhibited several components of both the kinin-kallikrein system and the coagulation cascades with potent and selective antisense oligonucleotides (ASOs) to investigate their relative contributions to vascular permeability. We have also developed ASO inhibitors of C1-INH and characterized their effects on vascular permeability in mice as an inducible model of HAE. Our studies demonstrate that ASO-mediated reduction in C1-INH plasma levels results in increased vascular permeability and that inhibition of proteases of the kinin-kallikrein system, either f12 or prekallikrein (PKK) reverse the effects of C1-INH depletion with similar effects on both basal and angiotensin converting enzyme (ACE) inhibitor-induced permeability. In contrast, inhibition of coagulation factors 11 (f11) or 7 (f7) had no effect. These results suggest that the vascular defects observed in C1-INH deficiency are dependent on the kinin-kallikrein system proteases f12 and PKK, and not mediated through the coagulation pathways. In addition, our results highlight a novel therapeutic modality that can potentially be employed prophylactically to prevent attacks in HAE patients. PMID:23582057

Bhattacharjee, Gourab; Revenko, Alexey S; Crosby, Jeffrey R; May, Chris; Gao, Dacao; Zhao, Chenguang; Monia, Brett P; MacLeod, A Robert

2013-06-01

76

Nucleation of silicon nanocrystals in a remote plasma without subsequent coagulation  

NASA Astrophysics Data System (ADS)

We report on the growth mechanism of spherical silicon nanocrystals in a remote expanding Ar plasma using a time-modulated SiH4 gas injection in the microsecond time range. Under identical time-modulation parameters, we varied the local density of the SiH4 gas by changing its stagnation pressure on the injection line over the range of 0.1-2.0 bar. We observed that nanocrystals were synthesized in a size range from ˜2 to ˜50 nm with monocrystalline morphology. Smaller nanocrystals (˜2-6 nm) with narrower size distributions and with higher number densities were synthesized with an increase of the SiH4 gas-phase density. We related this observation to the rapid depletion of the number density of the molecules, ions, and radicals in the plasma during nanocrystal growth, which can primarily occur via nucleation with no significant subsequent coagulation. In addition, in our remote plasma environment, rapid cooling of the gas in the particle growth zone from ˜1500 to ˜400 K significantly reduces the coalescence rate of the nanoparticles, which makes the coagulation process highly unlikely. Our observations on nanocrystal formation via nucleation indicated that subsequent coagulation for further growth is not always an essential step on nanoparticle formation.

Do?an, Ilker; Weeks, Stephen L.; Agarwal, Sumit; van de Sanden, Mauritius C. M.

2014-06-01

77

Effect of snake venom procoagulants on snake plasma: implications for the coagulation cascade of snakes.  

PubMed

Several snake venoms contain proteinases that activate zymogens in the coagulation cascade and thus exhibit their procoagulant effects. While most procoagulant proteinases from snake venoms are dissimilar to coagulation factors, Group D (trocarin, notecarin) and C (pseutarin) prothrombin activators are structural and functional homologues of factor Xa and the prothrombinase complex, respectively. We examined the effect of these and other procoagulants from snake venoms as well as mammalian and snake thromboplastins on the coagulation of plasmas of Notechis scutatus, Pseudonaja textilis (both procoagulant venoms), Python reticulatus (non-venomous) and Crotalus atrox (non-procoagulant venom) snakes. The results indicate that the intrinsic pathway seems to be weak or absent only in venomous snakes, while the extrinsic pathway is fully functional in all snakes. Python and Crotalus plasmas have extrinsic pathways similar to that in mammals. In contrast, although Notechis and Pseudonaja plasmas were clotted by a Group C activator, they failed to clot upon the addition of factor Xa and Group D activators. The mechanism of this resistance is still elusive. PMID:11689239

Joseph, Jeremiah S; Chung, Maxey C M; Mirtschin, Peter J; Kini, R Manjunatha

2002-02-01

78

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

79

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

80

Comparison of excitation temperature and electron temperature in low pressure argon plasmas  

Microsoft Academic Search

Compared to other active diagnostic methods, the optical emission spectroscopy (OES) method using an emission spectrum from the plasmas has a benefit of non-intrusive, in-situ monitoring of the plasmas. In this work, a study was performed to investigate the relation between the excitation temperature (obtained by OES) and the electron temperature (obtained by a Langmuir probe) in low pressure argon

Junkyu Rhee; Junghee Kim; Jongsub Lee; Seonghun Lee; Shinjae You; Hongyoung Chang; Wonho Choe

2006-01-01

81

Laser light scattering in a laser-induced argon plasma: Investigations of the B. Pokrzywka a  

E-print Network

. Introduction Laser-induced plasma (LIP) is an object of great interest, as it gives insight and complimentary experimental approach in LIP studies is the application of active laser methods: Raman, RayleighLaser light scattering in a laser-induced argon plasma: Investigations of the shock wave B

82

Investigations of laser-induced plasma in argon by Thomson scattering A. Mendys a,  

E-print Network

as of the electron density (ne) and electron temperature (Te). For laser induced plasma (LIP), the electron densityInvestigations of laser-induced plasma in argon by Thomson scattering A. Mendys a, , K. Dzierega Accepted 8 August 2011 Available online 16 August 2011 Keywords: Laser-induced breakdown spectroscopy

83

Measurement of Metastable Atom Populations Along an Argon Plasma Column Generated at Atmospheric Pressure  

Microsoft Academic Search

This paper describes a procedure for experimental determination of metastable and resonant populations along a surface wave argon plasma column at atmospheric pressure. As modeling work progresses extensively, an experimental database is necessary to confirm these models. Obtained results, within the range of values reported in literature, indicate that densities of metastable and resonant levels grow along the plasma column

Isabel Santiago; MarÍa Dolores Calzada

2009-01-01

84

Heat transfer between tungsten surface and glow discharge plasmas in argon and CO 2  

Microsoft Academic Search

A hot-filament method is used to study the heat transfer between tungsten surface and hollow-cathode glow discharge plasmas\\u000a 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\\u000a dioxide in the temperature range between 1000 and 1700 K. A difference in heat transfer at the

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

2009-01-01

85

Inactivation of human immunodeficiency virus by gamma radiation and its effect on plasma and coagulation factors  

SciTech Connect

The inactivation of HIV by gamma-radiation was studied in frozen and liquid plasma; a reduction of the virus titer of 5 to 6 logs was achieved at doses of 5 to 10 Mrad at -80 degrees C and 2.5 Mrad at 15 degrees C. The effect of irradiation on the biologic activity of a number of coagulation factors in plasma and in lyophilized concentrates of factor VIII (FVIII) and prothrombin complex was examined. A recovery of 85 percent of the biologic activity of therapeutic components present in frozen plasma and in lyophilized coagulation factor concentrates was reached at radiation doses as low as 1.5 and 0.5 Mrad, respectively. As derived from the first-order radiation inactivation curves, the radiosensitive target size of HIV was estimated to be 1 to 3 MDa; the target size of FVIII was estimated to be 130 to 160 kDa. Gamma radiation must be disregarded as a method for the sterilization of plasma and plasma-derived products, because of the low reduction of virus infectivity at radiation doses that still give acceptable recovery of biologic activity of plasma components.

Hiemstra, H.; Tersmette, M.; Vos, A.H.; Over, J.; van Berkel, M.P.; de Bree, H. (Central Laboratory of The Netherlands, Red Cross Blood Transfusion Service, Amsterdam (Netherlands))

1991-01-01

86

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

87

Modeling and simulation of ion-filtered inductively coupled plasma using argon plasma  

NASA Astrophysics Data System (ADS)

An ion-filtered inductively coupled plasma (IF-ICP) is proposed to reduce ion bombardment and provide high metastable species density for chemical vapor deposition. Argon plasma, which has simple reaction mechanism, is simulated to show the effects of ion filter. Compared to typical ICP, the maximum density of ions of IF-ICP is lower while that of metastable species is higher. The filter can absorb ions effectively and relatively small amount of metastable species, with the absorption coefficient proportional to its surface area. A proper gap between filter and substrate can achieve more metastable species and less ions on the substrate. The pressure and RF power need to be optimized based on the tradeoff between deposition rate and ion damage. The density of ions on the substrate can be reduced by two orders of magnitude while that of metastable species are maintained in the order of 1017 m?3 under the optimized conditions.

Wu, Chao; Wang, Jian; Zhang, Weiwang; Luo, Yi

2015-03-01

88

TUDE EXPRIMENTALE DE L'MISSION DE BREMSSTRAHLUNG LECTRON ATOME DANS UN JET DE PLASMA D'ARGON  

E-print Network

1829 �TUDE EXP�RIMENTALE DE L'�MISSION DE BREMSSTRAHLUNG �LECTRON ATOME DANS UN JET DE PLASMA D'ARGON,4 03BCm et 5 03BCm sur un jet de plasma d'argon faiblement ionisé en cours de recombinaison between 0.4 03BCm and 5 03BCm in a decay- ing argon plasmajet ; in visible and infra-red range, some

Boyer, Edmond

89

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

90

Microwave diagnostic for the determination of the electron temperature of a low density shock-heated argon plasma  

Microsoft Academic Search

The diffraction, defocusing and beam bending effects of microwaves transmitted through a bounded shock-heated argon plasma with low electron density are investigated with the purpose of developing an accurate method for electron temperature (Te) determination. This report describes the evaluation technique and presents results for an argon plasma with pressure between 3 and 10 torr, and T2 between 5500 and

C. P. Schneider; R. J. Exberger

1978-01-01

91

Surface modification of fluorosilicone acrylate RGP contact lens via low-temperature argon plasma  

NASA Astrophysics Data System (ADS)

A fluorosilicone acrylate rigid gas permeable (RGP) contact lens was modified via argon plasma to improve surface hydrophilicity and resistance to protein deposition. The influence of plasma treatment on surface chemical structure, hydrophilicity and morphology of RGP lens was investigated by X-ray photoelectron spectrometer (XPS), contact angle measurements and scanning electron microscope (SEM), respectively. The contact angle results showed that the hydrophilicity of the contact lens was improved after plasma treatment. XPS results indicated that the incorporation of oxygen-containing groups on surface and the transformation of silicone into hydrophilic silicate after plasma treatment are the main reasons for the surface hydrophilicity improvement. SEM results showed that argon plasma with higher power could lead to surface etching.

Yin, Shiheng; Wang, Yingjun; Ren, Li; Zhao, Lianna; Kuang, Tongchun; Chen, Hao; Qu, Jia

2008-11-01

92

Measurement Of The Distribution Of Ionization States In An Argon Plasma  

NASA Astrophysics Data System (ADS)

An experiment to measure the distribution of ionization states in an argon plasma proliaced by irradiating a gas-jet with 351-nm radiation from the OMEGA laser is described. The gas-jet was provided by Plasma Research Corporation. Its low divergence makes it possible to create a disk-shaped plasma region 1.5 mm diam x 1.5 mm thick over which the temperature and density are slowly varying. The experiment was performed at the Laboratory for Laser Energetics, University of Rochester, as part of the Department of energy's National Laser Users Facility Program. Eight beams of 60 J each were used to teat the argon gas-jet plasma. In the present experiment, a plasma temperature of about 65 eV was achieved at an electron density of about 1.0 x 1018. Lines in argon charge states VIII-XI have been ileatified in the spectra, and the results are compared with theoretical models which ,directly solve the time-dependent charge-state rate equations. It was found necessary to preionize the argon in order to couple in sufficient energy from the laser to produce a plasmasma.

Fisher, T. R.; Filbert, P. C.; Kohler, D.; Perez, J. D.; Walton, R.; Dahlbacka, G.

1988-02-01

93

Ionic Wind Phenomenon and Charge Carrier Mobility in Very High Density Argon Corona Discharge Plasma  

NASA Astrophysics Data System (ADS)

Wind ions phenomenon has been observed in the high density argon corona discharge plasma. Corona discharge plasma was produced by point to plane electrodes and high voltage DC. Light emission from the recombination process was observed visually. The light emission proper follow the electric field lines that occur between point and plane electrodes. By using saturation current, the mobilities of non-thermal electrons and ions have been obtained in argon gas and liquid with variation of density from 2,5 1021 to 2 1022 cm-3. In the case of ions, we found that the behaviour of the apparent mobility inversely proportional to the density or follow the Langevin variation law. For non-thermal electron, mobility decreases and approximately follows a variation of Langevin type until the density <= 0,25 the critical density of argon.

Nur, M.; Bonifaci, N.; Denat, A.

2014-04-01

94

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. PMID:22836883

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

95

Characterization of a low-pressure argon plasma using optical emission spectroscopy and a global model  

NASA Astrophysics Data System (ADS)

The excitation mechanisms of the lower lying excited levels in a low-ionized, low-pressure, argon plasma are modeled and studied in order to characterize the plasma through optical emission spectroscopy. It is found that the lower lying excited states of argon play an important role in the excitation and that they must be taken explicitly into account for an accurate determination of the excitation rates. The possible influence of radiative cascades from upper argon excited states, which are not included in the model, has been studied by introducing an effective level in the description and studying its influence on the results. The model has been used to calculate the electron density and electron temperature in an argon magnetron sputtering plasma produced at different electromagnetic powers and gas pressures, as a function of the intensity of the optical emission lines ?1=750.38nm and ?2=696.54nm. The results obtained from the model have been compared with Langmuir probe measurements, showing a good agreement. It is hereby demonstrated that optical emission spectroscopy can be used to monitor the plasma properties during the deposition process when applying a nonlinear model.

Palmero, A.; van Hattum, E. D.; Rudolph, H.; Habraken, F. H. P. M.

2007-03-01

96

Characterization of a low-pressure argon plasma using optical emission spectroscopy and a global model  

SciTech Connect

The excitation mechanisms of the lower lying excited levels in a low-ionized, low-pressure, argon plasma are modeled and studied in order to characterize the plasma through optical emission spectroscopy. It is found that the lower lying excited states of argon play an important role in the excitation and that they must be taken explicitly into account for an accurate determination of the excitation rates. The possible influence of radiative cascades from upper argon excited states, which are not included in the model, has been studied by introducing an effective level in the description and studying its influence on the results. The model has been used to calculate the electron density and electron temperature in an argon magnetron sputtering plasma produced at different electromagnetic powers and gas pressures, as a function of the intensity of the optical emission lines {lambda}{sub 1}=750.38 nm and {lambda}{sub 2}=696.54 nm. The results obtained from the model have been compared with Langmuir probe measurements, showing a good agreement. It is hereby demonstrated that optical emission spectroscopy can be used to monitor the plasma properties during the deposition process when applying a nonlinear model.

Palmero, A.; Hattum, E. D. van; Rudolph, H.; Habraken, F. H. P. M. [Surfaces, Interfaces and Devices, Department of Physics and Astronomy, Utrecht University, P.O. Box 80.000, 3508TA Utrecht (Netherlands)

2007-03-01

97

Transport coefficients of air, argon-air, nitrogen-air, and oxygen-air plasmas  

Microsoft Academic Search

Calculated values of the viscosity, thermal conductivity and electrical conductivity of air and mixtures of air and argon, air and nitrogen, and air and oxygen at high temperatures are presented. In addition, combined ordinary, pressure, and thermal diffusion coefficients are given for the gas mixtures. The calculations, which assione local thermodynamic equilibrium, are performed for atmospheric pressure plasmas in the

A. B. Murphy

1995-01-01

98

Inductively coupled argon plasma as an ion source for mass spectrometric determination of trace elements  

Microsoft Academic Search

Solution aerosols are injected into an inductively coupled argon plasma (ICP) to generate a relativly 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 vacuum system housing an ion lens and quadrupole mass spectrometer. The positive ion mass spectrum obtained during nebulization of

Robert S. Houk; Velmer A. Fassel; Gerald D. Flesch; Harry J. Svec; Alan L. Gray; Charles E. Taylor

1980-01-01

99

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...

100

Role of dissociative recombination in the excitation kinetics of an argon microwave plasma at atmospheric pressure  

Microsoft Academic Search

A collisional radiative model was developed in order to investigate the influence of dissociative recombination on the Saha–Boltzmann plasma equilibrium. As the dissociative recombination products are not well known, their relative importance was tested through comparison with the distribution of line intensities obtained in a microwave argon discharge produced at atmospheric pressure by a surface wave. It was found that

A. Sa´inz; J. Margot; M. C. Garci´a; M. D. Calzada

2005-01-01

101

Role of dissociative recombination in the excitation kinetics of an argon microwave plasma at atmospheric pressure  

Microsoft Academic Search

A collisional radiative model was developed in order to investigate the influence of dissociative recombination on the Saha-Boltzmann plasma equilibrium. As the dissociative recombination products are not well known, their relative importance was tested through comparison with the distribution of line intensities obtained in a microwave argon discharge produced at atmospheric pressure by a surface wave. It was found that

A. Sáinz; J. Margot; M. C. García; M. D. Calzada

2005-01-01

102

Theoretical Study of Plasma Parameters Dependence on Gas Temperature in an Atmospheric Pressure Argon Microwave Discharge  

Microsoft Academic Search

The gas temperature is an important parameter in many applications of atmospheric pressure microwave discharges (MW). That is why it is necessary to study the influence of that temperature on the plasma characteristics. Our investigation is based on a self-consistent model including the wave electrodynamics and gas-discharge kinetics. We adopt a blocks' energy structure of the argon excited atom. More

M. Pencheva; E. Benova; I. Zhelyazkov

2008-01-01

103

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

104

Modelling of an inductively coupled plasma torch with argon at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A fluid dynamic model is used to simulate the electromagnetic field, fluid flow and heat transfer in an inductively coupled plasma torch working at atmospheric pressure for argon plasma. The numerical simulation is carried out by using the finite element method based on COMSOL software. The two-dimensional profiles of the electric field, temperature, velocity and charged particle densities are demonstrated inside the discharge region. These numerical results are obtained for a fixed flow rate, frequency and electric power.

Bahouh, Hanene; Rebiai, Saida; Rochette, David; Vacher, Damien; Dudeck, Michel

2014-05-01

105

Activation of the fibrinolytic, coagulation and plasma kallikrein-kinin systems during and after open heart surgery in children.  

PubMed

Activation of the fibrinolytic, coagulation and plasma kallikrein-kinin systems may be responsible for some of the coagulation disorders and inflammatory sequelae seen after extracorporeal circulation. The activation pattern of these systems was studied in 10 children undergoing open heart surgery with extracorporeal circulation. Blood samples were drawn serially before, during and up to 48 h after surgery. The heparin injection induced a significant elevation of plasmin (PL) (p < 0.05) which stayed elevated during extracorporeal circulation. Antiplasmin (AP) values were reduced at wound closure, while the levels were significantly elevated 48 h postoperatively (p < 0.05). alpha 2-antiplasmin-plasmin (APP) increased significantly perioperatively peaking 10 min after the initiation of cardiopulmonary bypass (p < 0.05). The coagulation markers thrombin-antithrombin (TAT) and the prothrombin fragment F1 & 2 increased significantly, peaking at wound closure and at termination of bypass respectively (p < 0.05). Plasma kallikrein (KK) values increased significantly with subsequent decreased levels of prekallikrein (PKK) and kallikrein inhibitor (KKI) after heparin injection. The KK level stayed elevated during cardiopulmonary bypass (CPB). The proenzyme functional inhibition index (PFI index), defined as the sum of deviations from the control values for proenzyme and functional inhibition values of the coagulation, fibrinolytic and plasma kallikrein-kinin systems, correlated significantly to the duration of cardiopulmonary bypass (p < 0.05). We conclude that open heart surgery in children activates the fibrinolytic, coagulation and plasma kallikrein-kinin systems. PMID:7569739

Saatvedt, K; Lindberg, H; Michelsen, S; Pedersen, T; Geiran, O R

1995-07-01

106

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

SciTech Connect

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.; Kuehnel, M.; Schottelius, A. [Institut fuer Kernphysik, J. W. Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Hochhaus, D. C.; Neumayer, P. [EMMI Extreme Matter Institute and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); FIAS Frankfurt Institute for Advanced Studies, J. W. Goethe-Universitaet, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Polz, J. [Institut fuer Optik und Quantenelektronik, Max-Wien-Platz 1, 07743 Jena (Germany); Kaluza, M. C. [Institut fuer Optik und Quantenelektronik, Max-Wien-Platz 1, 07743 Jena (Germany); Helmholtz-Institut Jena, Froebelstieg 3, 07743 Jena (Germany); Grisenti, R. E. [Institut fuer Kernphysik, J. W. Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

2012-02-15

107

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

PubMed

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. PMID:22380120

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

2012-02-01

108

Contamination d'un plasma d'argon par des vapeurs anodiques de cuivre P. Andanson et B. Cheminat  

E-print Network

775 Contamination d'un plasma d'argon par des vapeurs anodiques de cuivre P. Andanson et B proche de l'anode en cuivre (1 mm à 1 cm) d'un arc stabilisé sous atmosphère d'argon (15 A et 30 A) est arc discharge in argon (15 A and 30 A) is studied. An important drop in temperature due to the metal

Boyer, Edmond

109

An argon-nitrogen-hydrogen mixed-gas plasma as a robust ionization source for inductively coupled plasma mass spectrometry  

NASA Astrophysics Data System (ADS)

Multivariate optimization of an argon-nitrogen-hydrogen mixed-gas plasma for minimum matrix effects, while maintaining analyte sensitivity as much as possible, was carried out in inductively coupled plasma mass spectrometry. In the presence of 0.1 M Na, the 33.9 ± 3.9% (n = 13 elements) analyte signal suppression on average observed in an all-argon plasma was alleviated with the optimized mixed-gas plasma, the average being - 4.0 ± 8.8%, with enhancement in several cases. An addition of 2.3% v/v N2 in the outer plasma gas, and 0.50% v/v H2 to the central channel, as a sheath around the nebulizer gas flow, was sufficient for this drastic increase in robustness. It also reduced the background from ArO+ and Ar2+ as well as oxide levels by over an order of magnitude. On the other hand, the background from NO+ and ArN+ increased by up to an order of magnitude while the levels of doubly-charged ions increased to 7% (versus 2.7% in an argon plasma optimized for sensitivity). Furthermore, detection limits were generally degraded by 5 to 15 fold when using the mixed-gas plasma versus the argon plasma for matrix-free solution (although they were better for several elements in 0.1 M Na). Nonetheless, the drastically increased robustness allowed the direct quantitative multielement analysis of certified ore reference materials, as well as the determination of Mo and Cd in seawater, without using any matrix-matching or internal standardization.

Makonnen, Yoseif; Beauchemin, Diane

2014-09-01

110

Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores  

SciTech Connect

A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. 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. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe [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)

2007-09-15

111

Acute gastric necrosis after routine oesophagogastroduodenoscopy with therapeutic argon plasma coagulation.  

PubMed

A 56-year-old woman presented to the accident and emergency department with peritonitis 2 days after a routine oesophagogastroduodenoscopy. She was taken to theatre with the finding of gastric necrosis. Blood and peritoneal cultures grew group A haemolytic Streptococcus. Histology revealed normal vasculature, no volvulus but marked neutrophilia in the submucosa with an intact mucosa. The stomach was resected and the patient recovered in the intensive care unit but overwhelming acidosis progressed to multiorgan failure and treatment was eventually withdrawn. Acute phlegmonous gastritis has been well described in the literature but mainly before the advent of antibiotics. The most common organism is group A haemolytic Streptococcus (commonly found in throat infections) and predisposing factors include instrumentation. Should antibiotics be given at the start of an oesophagogastroduodenoscopy and should routine procedures be delayed if active upper respiratory tract infections are present? PMID:24025279

Sahnan, K; Davis, B J H; Bagenal, J; Cullen, S; Appleton, S

2013-09-01

112

Modeling of ionization composition in argon plasma with fast electrons  

Microsoft Academic Search

Discharge and laser produced plasmas often have non-equilibrium electron distributions containing fast electrons that may\\u000a have a profound effect on the ionization balance. The influence of high energy electrons on the ionization balance in the\\u000a collisional-radiative equilibrium model for optically thin plasma is considered forthwith. A nonmaxwellian electron distribution\\u000a with fast electrons at energies and concentrations is used for calculating

V. S. Zakharov; V. G. Novikov

2009-01-01

113

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

114

Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure  

Microsoft Academic Search

This work presents a few preliminary results from a collisional-radiative\\u000a(CR) model intended to describe an argon microwave (2.45 GHz) plasma at\\u000aatmospheric pressure. This model aims to investigate the influence of\\u000adissociative recombination products on the Saha-Boltzmann plasma equilibrium.\\u000aThe model is tested through comparison with experimental results obtained in an\\u000aargon plasma column generated by a traveling electromagnetic

Abel Sainz; Joelle Margot; Maria Carmen Garcia; Maria Dolores Calzada

2004-01-01

115

Oral Bacterial Deactivation Using a Low-Temperature Atmospheric Argon Plasma Brush  

PubMed Central

Summary Objectives To study the plasma treatment effects on deactivation effectiveness of oral bacteria. Methods A low temperature atmospheric argon plasma brush were used to study the oral bacterial deactivation effects in terms of plasma conditions, plasma exposure time, and bacterial supporting media. Oral bacteria of Streptococcus mutans and Lactobacillus acidophilus with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. Scanning electron microscopy was used to examine the morphological changes of the plasma treated bacteria. Optical absorption was used to determine the leakage of intracellular proteins and DNAs of the plasma treated bacteria. Results The experimental data indicated that the argon atmospheric plasma brush was very effective in deactivating oral bacteria. The plasma exposure time for a 99.9999% cell reduction was less than 15 seconds for S. mutans and within 5 minutes for L. acidophilus. It was found that the plasma deactivation efficiency was also dependent on the bacterial supporting media. With plasma exposure, significant damages to bacterial cell structures were observed with both bacterium species. Leakage of intracellular proteins and DNAs after plasma exposure was observed through monitoring the absorbance peaks at wavelengths of 280nm and 260nm, respectively. Conclusion The experimental results from this study indicated that low temperature atmospheric plasma treatment was very effective in deactivation of oral bacteria and could be a promising technique in various dental clinical applications such as bacterial disinfection and caries early prevention, etc. PMID:20951184

Yang, Bo; Chen, Jierong; Yu, Qingsong; Li, Hao; Lin, Mengshi; Mustapha, Azlin; Hong, Liang; Wang, Yong

2010-01-01

116

Interpretation of the optical emission of argon in the plume of the Advanced Plasma Source  

NASA Astrophysics Data System (ADS)

The plume of the argon plasma of the Advanced Plasma Source employed for the deposition of optical coatings has been investigated by means of optical emission spectroscopy, Langmuir probe measurements as well as collisional radiative modeling using the measured electron energy probability function as the input. The emission of the ten argon lines considered is found to exhibit a cone-shaped spatial distribution. The emission on the axis of symmetry decreases exponentially with increasing distance from the source in good agreement with the results obtained by collisional radiative modeling and the radial extension of the Gaussian profile in the radial direction increases linearly along the axial direction. The analysis of the measured electron properties shows in particular that the electron pressure varies between about 2 Pa near the plasma source exit and 1 mPa at larger distances. The argon neutral density determined by collisional radiative modeling is found to be about 6 · 1011 cm?3 in the plasma plume in front of the source exit corresponding to a degree of ionization as high as 60%.

Harhausen, J.; Loffhagen, D.; Foest, R.

2015-02-01

117

Experimental Investigation of Laser-sustained Plasma in Supersonic Argon Flow  

NASA Astrophysics Data System (ADS)

Laser-induced energy deposition is widely discussed as a flow control technique in supersonic transportation. In case of thermal laser-plasma upstream of a blunt body, a substantial adaptation of shock wave geometry and magnitude of wave drag is predicted. Related to the research on laser supported detonation, the paper describes the implementation of laser-sustained plasma in a supersonic Argon jet. The stable plasma state is generated by the intersection of a Q-switched Nd:YAG-laser and a continuous wave CO2-laser beams, for ignition and maintenance of the plasma respectively. A miniature supersonic Ludwieg tube test facility generates a supersonic jet at velocities of Mach 2.1. Modifications of the flow and plasma conditions are investigated and characterized by Schlieren flow visualisation, laser energy transmission and plasma radiation measurements. The results include the discussions of the flow field as well as the required laser and gas parameters.

Sperber, David; Eckel, Hans-Albert; Moessinger, Peter; Fasoulas, Stefanos

2011-11-01

118

XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene  

NASA Technical Reports Server (NTRS)

The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

Golub, Morton A.; Kliss, Mark (Technical Monitor)

1997-01-01

119

Soft X-ray spectroscopic study of a gas-puff Z-pinch argon plasma  

Microsoft Academic Search

X-ray radiation characteristics of argon plasma produced by a gas-puff Z-pinch device were investigated using an X-ray crystal spectrometer, an X-ray diode, and an extreme ultraviolet (XUV) spectrometer. Using a germanium crystal we have observed spectral emission from Ar XVII produced by hot spots at the pinched stage. With the help of a 2-m grazing incidence XUV spectrometer, the spectrum

Seong Ho Kim; Dong-Eon Kim; Tong Nyong Lee

1998-01-01

120

Atom-atom inelastic collisions and three-body atomic recombination in weakly ionized argon plasmas  

NASA Technical Reports Server (NTRS)

A stationary collisional-radiative model including both inelastic electron-atom and atom-atom collisions is used to examine nonequilibrium weakly ionized argon plasmas with atomic densities 10 to the 16th to 10 to the 20th/cu cm, temperatures below 6000 K, and with different degrees of radiation trapping. It is shown that three-body atomic recombination becomes important at high particle densities. Comparison is made between the present approach and Thomson's theory for atomic recombination.

Braun, C. G.; Kunc, J. A.

1989-01-01

121

“Hot electrons” influence on argon K-spectrum emitted from Plasma Focus discharges  

Microsoft Academic Search

New results of spectroscopical investigation of Plasma Focus discharges performed on the PF-1000 facility (IPPiLM, Warsaw)\\u000a are presented. Two-dimensional space resolved K-sheel spectra of argon were registered using a mica crystal spectrometer of\\u000a FSSR-2D type. The important role of the electron beam in forming of these spectra is shown. A modeling of the spectra by the\\u000a collisional-radiative theory with inclusion

L. Karpinski; M. Paduch; M. Scholz; K. Tomaszewski; A. Szydlowski; S. Pikuz; V. Romanova; A. Ya. Faenov; J. Abdallah; R. E. H. Clark

2000-01-01

122

Comparison of atmospheric-pressure helium and argon plasmas generated by capacitively coupled radio-frequency discharge  

NASA Astrophysics Data System (ADS)

In this paper, the electrical discharge characteristics of plasmas generated in coaxial cylindrical electrodes capacitively powered by a radio-frequency power supply at atmospheric pressure are investigated with respect to helium and argon gases. The electrical discharge parameters, voltage (V), current (I), and power (P), are measured for both helium and argon plasmas, and the electron temperatures and electron densities for them are evaluated by means of the equivalent circuit model and the power balance equation. By comparison of the discharge characteristics of the helium and argon plasmas, it is found that the discrepant macroscopic characteristics of helium and argon plasma, viz., current and voltage characteristics and current and power characteristics, are owed to their own intrinsic microscopic parameters of the helium and argon atoms, such as the first excited energy, the ionization energy, the total cross section, and the atom mass. Furthermore, the influences of the additive gas, oxygen gas, on the electrical discharge characteristics are also investigated in the helium and argon plasmas, which are closely related to the electron temperature of plasmas.

Li, Shou-Zhe; Lim, Jin-Pyo; Kang, Jung G.; Uhm, Han S.

2006-09-01

123

Activation of plasma coagulation by retransfusion of unwashed drainage blood after hip joint arthroplasty: a prospective study.  

PubMed

Twelve patients undergoing cementless hip joint arthroplasty were retransfused with unwashed drainage blood collected postoperatively. Global coagulation parameters, coagulation factors (factor V:C, factor VIII:C, activated factor XII, and factor XIII) and markers of thrombin generation (F1+2 Fibrin split products, thrombin-antithrombin complexes), fibrin generation (fibrinogen and fibrin degradation products), and fibrinolysis (D-dimers, thrombin degradation products, plasminogen) were determined. High levels of factor XIIa, thrombin and fibrin generation markers, and markers of fibrinolysis were present in the shed blood. After retransfusion (mean, 433 mL), increased levels of these markers together with decreased values for factor XIII and plasminogen were indicative of renewed clot formation and fibrinolysis in the circulation. These changes were highly significant compared with preretransfusion values. The unwashed drainage blood contained high levels of procoagulation material and induced an activation of the plasma coagulation pathway with renewed clot formation and fibrinolysis in the patients. PMID:11607899

Duchow, J; Ames, M; Hess, T; Seyfert, U

2001-10-01

124

Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics  

SciTech Connect

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., E-mail: a_alex@itam.nsc.ru; Schweigert, I. V.; Ariskin, D. A. [Siberian Branch of the Russian Academy of Sciences, Institute of Theoretical and Applied Mechanics (Russian Federation)

2013-04-15

125

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

126

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

127

Comparison of temperature and composition measurement by spectroscopic methods for argon-helium arc plasma  

NASA Astrophysics Data System (ADS)

Three different spectroscopic methods were used to calculate the temperature and composition distribution of argon-helium arc plasma-the Fowler-Milne method, the two-line intensity correlation method and the Boltzmann plot method. Experimental errors, including random errors and systematic errors, were analyzed in detail to comparing the accuracy of different methods. Due to the large differences of physical characteristics between argon and helium, there were limited reports on the measurement of temperature and composition distribution in argon-helium arc plasma. To this end, The Fowler-Milne method and the Boltzmann plot method were modified in this paper. Three spectroscopic methods were compared with other's simulation result and showed good agreement with each other, except the Boltzmann plot method which had partly distinction. Through comparison and analysis of error bar in those methods, it was found that both the Fowler-Milne method and the two-line intensity correlation method had less error than the Boltzmann plot method, while the Fowler-Milne method, which is irrelevant to atomic transition probabilities and experimental apparatus calibration, had the minimum error.

Xiao, Xiao; Hua, Xueming; Wu, Yixiong

2015-03-01

128

Influence of centrifuge brake on residual platelet count and routine coagulation tests in citrated plasma.  

PubMed

Sample centrifugation is an essential step in the coagulation laboratory, as clotting tests are typically performed on citrated platelet (PLT) poor plasma (PPP). Nevertheless, no clear indication has been provided as to whether centrifugation of specimens should be performed with the centrifuge brake set to on or off. Fifty consecutive sodium citrate anticoagulated samples were collected and divided into two aliquots. The former was centrifuged as for Clinical Laboratory Standards Institute (CLSI) guidelines with the centrifuge brake set to on, whereas the latter was centrifuged again as for CLSI guidelines, but with the brake set to off. In the PPP of all samples, a PLT count was performed, followed by the analysis of activated partial thromboplastin time (APTT), prothrombin time (PT) and fibrinogen (FBG). The PLT count after samples centrifugation was substantially reduced, either with centrifuge brake set to on or off (5?±?1 versus 3?±?1?×?10/l; P?=?0.009). The frequency of samples exceeding a PLT count less than 10?×?10/l was nearly double in samples centrifuged with the brake on than in those with the brake off (14 versus 8%; P?coagulation testing should be preferably performed with the centrifuge brake set to off for providing a better quality specimen. PMID:24389587

Daves, Massimo; Giacomuzzi, Katia; Tagnin, Enrico; Jani, Erika; Adcock Funk, Dorothy M; Favaloro, Emmanuel J; Lippi, Giuseppe

2014-04-01

129

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

130

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

131

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

SciTech Connect

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 2p{sub 9}-1s{sub 5}, 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 1s{sub 2} and 1s{sub 4} are sufficiently optically thin and ratios of population densities are constant.

Scharwitz, Christian; Makabe, Toshiaki [Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, 223-8522 (Japan)

2009-12-01

132

Theoretical study of nanoparticle formation in thermal plasma processing: Nucleation, coagulation and aggregation  

NASA Astrophysics Data System (ADS)

This work presents a mathematical modeling study of the synthesis of nanoparticles in radio frequency (RF) inductively coupled plasma (ICP) reactors. The purpose is to further investigate the influence of process parameters on the final size and morphology of produced particles. The proposed model involves the calculation of flow and temperature fields of the plasma gas. Evaporation of raw particles is also accounted with the particle trajectory and temperature history calculated with a Lagrangian approach. The nanoparticle formation is considered by homogeneous nucleation and the growth is caused by condensation and Brownian coagulation. The growth of fractal aggregates is considered by introducing a power law exponent Df. Transport of nanoparticles occurs by convection, thermophoresis and Brownian diffusion. The method of moments is used to solve the particle dynamics equation. The model is validated using experimental results from plasma reactors at laboratory scale. The results are presented in the following manner. First, use is made of the computational fluid dynamics software (CFD), Fluent 6.1 with a commercial companion package specifically developped for aerosols named: Fine Particle Model (FPM). This package is used to study the relationship between the operating parameters effect and the properties of the end products at the laboratory scale. Secondly, a coupled hybrid model for the synthesis of spherical particles and fractal aggregates is developped in place of the FPM package. Results obtained from this model will allow to identify the importance of each parameter in defining the morphology of spherical primary particles and fractal aggregates of nanoparticles. The solution of the model was made using the geometries and operating conditions of existing reactors at the Centre de Recherche en Energie, Plasma et Electrochimie (CREPE) of the Universite de Sherbrooke, for which experimental results were obtained experimentally. Additionally, this study demonstrates the importance of the flow and temperature fields on the growth of fractal particles; namely the aggregates.

Mendoza Gonzalez, Norma Yadira

133

Comparison of the effects of CORM-2, CORM-3 and CORM-A1 on coagulation in human plasma.  

PubMed

Carbon monoxide derived from the catalytic action of heme oxygenase-1 or carbon monoxide-releasing molecules (CORMs) has been found to potentially be an anticoagulant or procoagulant agent. Of interest, two water-soluble CORMs, CORM-3 and CORM-A1, recently became commercially available. Thus, the purpose of the present study was to assess and compare the effects of the previously well studied CORM-2 to the effects of CORM-3 and CORM-A1 on coagulation in citrated human plasma with thrombelastography. Plasma exposed to CORMs was incubated at 37°C for at least one carbon monoxide release half-time, and then tissue factor-activated coagulation was commenced with calcium addition. CORM-2 and CORM-3 enhanced the velocity of clot formation and thrombus strength in a similar manner, whereas CORM-A1 did not affect coagulation. However, CORM-A1 did diminish tissue-type plasminogen activator initiated fibrinolysis. The similarity in effect on coagulation by CORM-2 and CORM-3 was likely secondary to the relatively inert effect of their ruthenium-containing carrier molecule, whereas the boron-containing CORM-A1 may have had no effect secondary to boron binding to fibrinogen, preventing carbon monoxide-mediated changes in fibrinogen protein structure via attached heme group(s). Future investigations with CORMs should have special attention to confounding effects of the carrier molecule. PMID:25058038

Nielsen, Vance G; Garza, Joshua I

2014-12-01

134

Optical diagnostics of a low power---low gas flow rates atmospheric-pressure argon plasma created by a microwave plasma torch  

Microsoft Academic Search

We employ a suite of optical techniques, namely, visual imaging, optical emission spectroscopy and cavity ringdown spectroscopy (CRDS), to characterize a low power, low gas flow rates, atmospheric-pressure argon microwave induced plasma. The plasma is created by a microwave plasma torch, which is excited by a 2.45 GHz microwave with powers ranging from 60 to 120 W. A series of

Chuji Wang; Nimisha Srivastava; Susan Scherrer; Ping-Rey Jang; Theodore S. Dibble; Yixiang Duan

2009-01-01

135

Mass spectrometric characterization of N- and O-glycans of plasma-derived coagulation factor VII.  

PubMed

Factor VII (FVII) is a vitamin K-dependent glycoprotein which, in its activated form (FVIIa), participates in the coagulation process by activating factor X and factor IX. FVII is secreted as single peptide chain of 406 residues. Plasma-derived FVII undergoes many post-translational modifications such as gamma-carboxylation, N- and O-glycosylation, beta-hydroxylation. Despite glycosylation of recombinant FVIIa has been fully characterized, nothing is reported on the N- and O-glycans of plasma-derived FVII (pd-FVII) and on their structural heterogeneity at each glycosylation site. N- and O-glycosylation sites and site specific heterogeneity of pd-FVII were studied by various complementary qualitative and quantitative techniques. A MALDI-MS analysis of the native protein indicated that FVII is a 50.1 kDa glycoprotein modified on two sites by diantennary, disialylated non-fucosylated (A2S2) glycans. LC-ESIMS/MS analysis revealed that both light chain and heavy chain were N-glycosylated mainly by A2S2 but also by triantennary sialylated glycans. Nevertheless, lower amounts of triantennary structures were found on Asn(322) compared to Asn(145). Moreover, the triantennary glycans were shown to be fucosylated. In parallel, quantitative analysis of the isolated glycans by capillary electrophoresis indicated that the diantennary structures represented about 50% of the total glycan content. Glycan sequencing using different glycanases led to the identification of triantennary difucosylated structures. Last, MS and MS/MS analysis revealed that FVII is O-glycosylated on the light chain at position Ser(60) and Ser(52) which are modified by oligosaccharide structures such as fucose and Glc(Xyl)(0-1-2), respectively. These latter three O-glycans coexist in equal amounts in plasma-derived FVII. PMID:18642129

Fenaille, François; Groseil, Catherine; Ramon, Christine; Riandé, Sandrine; Siret, Laurent; Chtourou, Sami; Bihoreau, Nicolas

2008-12-01

136

The role of visible and resonance radiation in the energy balance of LTE plasma in argon  

NASA Astrophysics Data System (ADS)

Energy losses due to radiation in an LTE arc plasma in argon are investigated in the temperature range from 5000 to 15?000 K. Calculations of the radiation transport require us to know the absorption spectra; for that purpose, free–free, bound–free and bound–bound transitions are taken into account. The energy losses due to resonance transitions with large absorption coefficients are analyzed. The transport of visible radiation with small absorption coefficients is calculated by accurate integration over a whole spectrum. The resonance radiation transport in LTE plasma is described by the Biberman–Holstein equation, which is usually used in non-equilibrium plasma. As the temperature grows, radiation processes become the main channel of energy losses. It is shown that, despite the resonance radiation being trapped, the energy losses due to resonance radiation escape can achieve 10% of the total radiation losses.

Golubovskii, Yu B.; Maiorov, V. A.; Gorchakov, S.; Uhrlandt, D.

2015-02-01

137

CARACTRISTIQUES D'UN PLASMA D'ARGON FORTEMENT IONIS DANS UNE DCHARGE PULSE A BASSE PRESSION  

E-print Network

659 CARACT�RISTIQUES D'UN PLASMA D'ARGON FORTEMENT IONIS� DANS UNE D�CHARGE PULS�E A BASSE PRESSION J. JOLLY Laboratoire de Physique des Plasmas (*), Université Paris XI, Bâtiment 212, 91405 Orsay of the discharge parameters : current density, filling pressure and tube radius. This model is applicable to pulsed

Paris-Sud XI, Université de

138

Improved measurement of the electron temperature of a low density shock-heated argon plasma by means of microwaves  

Microsoft Academic Search

Determining electron temperature in a low-density shock-heated argon plasma via microwave diagnostics is studied. A test section is developed permitting the simultaneous transmission of two microwave beams at different frequencies. Two corrections are applied to the measured attenuation of the transmitted waves in order to obtain the true attenuation due to wave power dissipation into the plasma, dependent on electron

C. P. Schneider

1978-01-01

139

Argon–oxygen dc magnetron discharge plasma probed with ion acoustic waves  

SciTech Connect

The precise determination of the relative concentration of negative ions is very important for the optimization of magnetron sputtering processes, especially for those undertaken in a multicomponent background produced by adding electronegative gases, such as oxygen, to the discharge. The temporal behavior of an ion acoustic wave excited from a stainless steel grid inside the plasma chamber is used to determine the relative negative ion concentration in the magnetron discharge plasma. The phase velocity of the ion acoustic wave in the presence of negative ions is found to be faster than in a pure argon plasma, and the phase velocity increases with the oxygen partial pressure. Optical emission spectroscopy further confirms the increase in the oxygen negative ion density, along with a decrease in the argon positive ion density under the same discharge conditions. The relative negative ion concentration values measured by ion acoustic waves are compared with those measured by a single Langmuir probe, and a similarity in the results obtained by both techniques is observed.

Saikia, Partha, E-mail: partha.008@gmail.com; Saikia, Bipul Kumar; Goswami, Kalyan Sindhu [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur, Kamrup, Assam 782 402 (India); Phukan, Arindam [Madhabdev College, Narayanpur, Lakhimpur, Assam 784164 (India)

2014-05-15

140

Comparison of surface vacuum ultraviolet emissions with resonance level number densities. I. Argon plasmas  

SciTech Connect

Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. The highly energetic photons can induce surface damage by driving surface reactions, disordering surface regions, and affecting bonds in the bulk material. In argon plasmas, the VUV emissions are due to the decay of the 1s{sub 4} and 1s{sub 2} principal resonance levels with emission wavelengths of 104.8 and 106.7?nm, respectively. The authors have measured the number densities of atoms in the two resonance levels using both white light optical absorption spectroscopy and radiation-trapping induced changes in the 3p{sup 5}4p?3p{sup 5}4s branching fractions measured via visible/near-infrared optical emission spectroscopy in an argon inductively coupled plasma as a function of both pressure and power. An emission model that takes into account radiation trapping was used to calculate the VUV emission rate. The model results were compared to experimental measurements made with a National Institute of Standards and Technology-calibrated VUV photodiode. The photodiode and model results are in generally good accord and reveal a strong dependence on the neutral gas temperature.

Boffard, John B., E-mail: jboffard@wisc.edu; Lin, Chun C. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Culver, Cody [Materials Science Program, University of Wisconsin, Madison, WI 53706 (United States); Wang, Shicong; Wendt, Amy E. [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI 53706 (United States); Radovanov, Svetlana; Persing, Harold [Varian Semiconductor Equipment, Applied Materials Inc., Gloucester, MA 01939 (United States)

2014-03-15

141

Ozone-stimulated emission due to atomic oxygen population inversions in an argon microwave plasma torch  

SciTech Connect

It is shown that, in a microwave torch discharge in an argon jet injected into an oxygen atmosphere at normal pressure, quasi-resonant energy transfer from metastable argon atoms to molecules of oxygen and ozone generated in the torch shell and, then, to oxygen atoms produced via the dissociation of molecular oxygen and ozone leads to the inverse population of metastable levels of atomic oxygen. As a result, the excited atomic oxygen with population inversions becomes a gain medium for lasing at wavelengths of 844.6 and 777.3 nm (the 3{sup 3}P-3{sup 3}S and 3{sup 5}P-3{sup 5}S transitions). It is shown that an increase in the ozone density is accompanied by an increase in both the lasing efficiency at these wavelength and the emission intensity of the plasma-forming argon at a wavelength of 811.15 nm (the {sup 2}P{sup 0}4s-{sup 2}P{sup 0}4p transition). When the torch operates unstably, the production of singlet oxygen suppresses ozone generation; as a result, the lasing effect at these wavelengths disappears.

Lukina, N. A.; Sergeichev, K. F. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation)

2008-06-15

142

Waves generated in the vicinity of an argon plasma gun in the ionosphere  

NASA Technical Reports Server (NTRS)

Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.

Cahill, L. J., Jr.; Arnoldy, R. L.; Lysak, R. L.; Peria, W.; Lynch, K. A.

1993-01-01

143

Solvent\\/detergent plasma for prevention of bleeding in recessively inherited coagulation disorders: dosing, pharmacokinetics and clinical efficacy  

Microsoft Academic Search

Design and Methods. In vivo recovery (IVR) of the deficient coagulation factor was deter- mined in a non-bleeding state in all patients and the mean values for FV, FVIII, FX, FXI and fibrinogen were 1.3, 1.2, 1.5, 1.3 and 1.5 dL\\/kg, respectively. The mean plasma half-life of FV, FVIII and FX was 18, 43 and 33 hours, respectively. All patients

Elena Santagostino; Maria Elisa Mancuso; Massimo Morfini; Mario Schiavoni; Annarita Tagliaferri; Giovanni Barillari; Pier Mannuccio Mannucci

144

Effect of neutral gas heating in argon radio frequency inductively coupled plasma  

NASA Astrophysics Data System (ADS)

Heating of neutral gas in inductively coupled plasma (ICP) is known to result in neutral gas depletion. In this work, this effect is considered in the simulation of the magnetic field distribution of a 13.56 MHz planar coil ICP. Measured electron temperatures and densities at argon pressures of 0.03, 0.07 and 0.2 mbar were used in the simulation whilst neutral gas temperatures were heuristically fitted. The simulated results showed reasonable agreement with the measured magnetic field profile.

Chin, O. H.; Jayapalan, K. K.; Wong, C. S.

2014-08-01

145

Numerical simulations of a nonequilibrium argon plasma in a shock-tube experiment  

NASA Technical Reports Server (NTRS)

A code developed for the numerical modeling of nonequilibrium radiative plasmas is applied to the simulation of the propagation of strong ionizing shock waves in argon gas. The simulations attempt to reproduce a series of shock-tube experiments which will be used to validate the numerical models and procedures. The ability to perform unsteady simulations makes it possible to observe some fluctuations in the shock propagation, coupled to the kinetic processes. A coupling mechanism by pressure waves, reminiscent of oscillation mechanisms observed in detonation waves, is described. The effect of upper atomic levels is also briefly discussed.

Cambier, Jean-Luc

1991-01-01

146

Effects of storage time and temperature on coagulation tests and factors in fresh plasma  

PubMed Central

Coagulation tests and factors measurements have been widely applied in clinical practice. Pre-analytical conditions are very important in laboratory assessment.Here,we aim to determine the effects of storage time and temperature on activated partial thromboplastin time (APTT), fibrinogen (Fbg), prothrombin time (PT), the international normalized ratio (INR), thrombin time (TT), factor VIII activity (FVIII:C), and factor IX activity (FIX:C) in fresh plasma. Seventy-two blood samples were tested after storage for 0 (baseline), 2, 4, 6, 8, 12, and 24?h at 25°C (room temperature) and 4°C (refrigeration) in two centers. The mean percentage change of greater than 10% and the numbers of samples with greater than 10% percentage changes more than 25% were used to determine clinically relevant difference. We demonstrated that samples for Fbg, PT/INR, and TT could be safely stored for ?24?h; FVIII:C for ?2?h; FIX:C for ?4?h both at 4°C and 25°C; and APTT for ?12?h at 4°C and ?8?h at 25°C. PMID:24463857

Feng, Limin; Zhao, Ying; Zhao, Hongcan; Shao, Zhexin

2014-01-01

147

Effect of secondary emission on the argon plasma afterglow with large dust density  

NASA Astrophysics Data System (ADS)

A zero-dimensional, space-averaged model for argon plasma afterglow with large dust density is developed. In the model, three groups of electrons in the plasma afterglow are assumed: (i) thermal electrons with Maxwellian distribution, (ii) energetic electrons generated by metastable-metastable collisions (metastable pooling), and (iii) secondary electrons generated at collisions of ions with the electrodes, which have sufficiently large negative voltages in the afterglow. The model calculates the time-dependencies for electron densities in plasma afterglow based on experimental decay times for metastable density and electrode bias. The effect of secondary emission on electron density in the afterglow is estimated by varying secondary emission yields. It is found that this effect is less important than metastable pooling. The case of dust-free plasma afterglow is considered also, and it is found that in the afterglow the effect of secondary emission may be more important than metastable pooling. The secondary emission may increase thermal electron density ne in dust-free and dusty plasma afterglows on a few ten percentages. The calculated time dependencies for ne in dust-free and dusty plasma afterglows describe well the experimental results.

Denysenko, I. B.; Stefanovi?, I.; Azarenkov, N. A.; Burmaka, G. P.

2015-02-01

148

Reactor geometry and plasma uniformity in a planar inductively coupled radio frequency argon discharge  

NASA Astrophysics Data System (ADS)

The effects of chamber height on plasma uniformity are examined for a cylindrically symmetric planar inductive radio frequency (rf) (13.56 MHz) argon plasma generated with a single-turn circular loop antenna. Plasma uniformity is characterized by two-dimensional 0963-0252/5/3/011/img1 spatial profiles of plasma properties measured with a rf-filtered Langmuir probe. The results show a tendency for the radial location of the plasma density maximum to shift from the centre outward as the chamber height is decreased and pressure is increased. The location of the density maximum is insensitive to changes in discharge power. These observations are explained as a consequence of changes in axial and radial transport of ionizing energetic electrons as the reactor height L is varied. Because electron heating is localized at the radius of the maximum induced rf electric field 0963-0252/5/3/011/img2, the critical scale lengths are 0963-0252/5/3/011/img2 and L, in addition to the energy relaxation length for ionizing electrons 0963-0252/5/3/011/img4. The competition between axial and radial losses can lead, for 0963-0252/5/3/011/img5, to a sensitive dependence of plasma uniformity on discharge operating conditions.

Stittsworth, J. A.; Wendt, A. E.

1996-08-01

149

Enhanced specificity of immunoblotting using radiolabeled antigen overlay: studies of blood coagulation factor XII and prekallikrein in plasma  

SciTech Connect

Immunoblotting of blood coagulation Factor XII and plasma prekallikrein in whole plasma was performed using radiolabeled antigen for detection. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis of plasma and transfer to nitrocellulose sheets, the blots were first reacted with polyclonal goat anti-Factor XII or anti-prekallikrein antisera and then with /sup 125/I-Factor XII or /sup 125/I-prekallikrein, respectively. A major advantage of using radiolabeled antigen rather than radiolabeled secondary antibody was enhanced specificity of immunodetection of these antigens in plasma. This procedure was sensitive to approx.0.3 ng of either Factor XII or prekallikrein antigen and was useful for detection of Factor XII cleavage fragments in contact activated plasma. Radiolabeled antigen overlay may improve the specificity of immunoblotting of trace antigens in any complex mixtures.

Laemmle, B.; Berrettini, M.; Griffin, J.H.

1986-01-01

150

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

151

Theoretical investigation of the effect of hydrogen addition on the formation and properties of soliton in direct current argon plasma  

SciTech Connect

In this study the effect of hydrogen addition on the formation and properties of soliton in direct-current (DC) argon plasma is theoretically investigated. By coupling fluid equations with Poisons equation for such multi-component plasma, the Mach number and amplitude of the soliton are determined following pseudo potential method. Addition of hydrogen in argon discharge leads to the decrease of electron, Ar{sup +} ion density while a reverse trend was observed for ArH{sup +} and hydrogen like ions. It was found that presence of hydrogen like ions in argon plasma affects the formation of soliton with its amplitude significantly decreases as concentration of hydrogen increases. On the other hand, increase in ion to electron temperature ratios of the lighter ions in the discharge also has a significant influence on the amplitude and formation of soliton. The inverse relation between solitons width and amplitude is found to be consistent for the entire range of study.

Saikia, P., E-mail: partha.008@gmail.com; Goswami, K. S.; Saikia, B. K. [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur, Kamrup, Assam-782 402 (India)] [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur, Kamrup, Assam-782 402 (India)

2014-03-15

152

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

153

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

154

Growth of thin silver films on silicon oxide pretreated by low temperature argon plasma  

NASA Astrophysics Data System (ADS)

In the present study, we investigate the influence of low energy ion bombardment on nucleation and growth of thin silver films on silicon oxide by in situ photoelectron spectroscopy (PES) combined with specific resistivity measurements. Thermally grown thin silicon oxide films were exposed to a low temperature argon plasma for different time intervals resulting in changes in surface chemical composition as monitored by angle-resolved X-ray photoelectron spectroscopy (ARXPS). We demonstrate that irradiation of the oxide surface with low energy ions results in substantially changed nucleation of silver. Furthermore, silver films deposited on plasma treated oxide tend to have lower resistivity which is attributed to the effect of reduced grain boundary and surface roughness.

Romanyuk, Andriy; Steiner, Roland; Mack, Iris; Oelhafen, Peter; Mathys, Daniel

2007-02-01

155

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

156

Activation of plasma coagulation by retransfusion of unwashed drainage blood after hip joint arthroplasty  

Microsoft Academic Search

Twelve patients undergoing cementless hip joint arthroplasty were retransfused with unwashed drainage blood collected postoperatively. Global coagulation parameters, coagulation factors (factor V:C, factor VIII:C, activated factor XII, and factor XIII) and markers of thrombin generation (F1+2 Fibrin split products, thrombin-antithrombin complexes), fibrin generation (fibrinogen and fibrin degradation products), and fibrinolysis (D-dimers, thrombin degradation products, plasminogen) were determined. High levels of

Jochen Duchow; Michael Ames; Thomas Hess; Ulrich Seyfert

2001-01-01

157

Clinical Outcomes of Percutaneous Plasma Disc Coagulation Therapy for Lumbar Herniated Disc Diseases  

PubMed Central

Objective This is prospective study of clinical outcomes of percutaneous plasma disc coagulation Therapy (PDCT) in patients with herniated lumbar disc disease (HLD) to evaluate the safety and efficacy in its clinical application and usefulness as a reliable alternative to microscopic discectomy. Methods Forty-six patients were enrolled in this study from April 2006 to June 2010. All patients had one-level HLD. Disc degeneration was graded on routine T2-weighted magnetic resonance Image (MRI) using the Pfirrmann's grading system and all index levels were grade 3 and grade 4. Indications for surgery were radiculopathy caused by disc protrusion with soft consistency. MRI was done at one month after the procedure in all patients to check post-PDCT change. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results This study was approved by the Institutional Review Board of our institution. The age of the study population ranged from 16 to 59 years with a mean age of 37.2 years. There were 29 males and 17 females in this study. The mean period of clinical follow-up was 21 months. The average preoperative VAS score for radiculopathy was 7.4±1.4, while the final follow-up VAS score was 1.4±0.7 (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. Conclusion PDCT is a safe and efficient treatment modality in a selective patient with HLD. PMID:22396836

Kim, Sung Chul; Cho, Ki Hong

2012-01-01

158

Drugs Modifying Nitric Oxide Metabolism Affect Plasma Cholesterol Levels, Coagulation Parameters, Blood Pressure Values and the Appearance of Plasma Myocardial Necrosis Markers in Rabbits: Opposite Effects of L-NAME and Nitroglycerine  

Microsoft Academic Search

Various experiments have shown that decreased nitric oxide values alter plasma lipid levels or coagulation parameters or blood pressure values or cause myocardial necrosis phenomena, but it is not clear whether these alterations are reciprocally connected, or whether nitric oxide changes are involved in the appearance of some coronary disease risk factors (lipid, coagulation, blood pressure alterations) and myocardial necrosis.

Arnaldo Pinelli; Silvio Trivulzio; Livio Tomasoni; Boris Bertolini; Sergio Brenna; Edgardo Bonacina; Roberto Accinni

2003-01-01

159

Temporally and spatially resolved characterization of microwave induced argon plasmas: Experiment and modeling  

SciTech Connect

Experiments and modeling of the plasma-microwave interaction have been performed in a coaxial microwave plasma source at a field frequency of 2.45 GHz generating argon plasmas at pressures of 20 and 40 millibars and a ratio of flow rate to pressure of 0.125 sccm/Pa. The incident microwave power between 100?W and 300?W is supplied in a regime of a pulse-width modulation with cycle duration of 110?ms and a power-on time of 23?ms. The experiments are based on heterodyne reflectometry and microwave interferometry at 45.75?GHz. They provide the temporal behaviour of the complex reflection coefficient, the microwave power in the plasma, as well as the electron density in the afterglow zone of the discharge. The self-consistent spatially two-dimensional and time-dependent modeling complements the analysis of the plasma-microwave interaction delivering the plasma and electromagnetic field parameters. The consolidating experimental observations and model predictions allow further characterizing the plasma source. The generated plasma has a core occupying the region close to the end of the inner electrode, where maximum electron densities above 10{sup 20}?m{sup ?3} and electron temperatures of about 1?eV are observed. Due to a longer outer electrode of the coaxial structure, the plasma region is extended and fills the volume comprised by the outer electrode. The electron density reaches values of the order of 10{sup 19}?m{sup ?3}. The heating of the gas occurs in its great part due to elastic collisions with the plasma electrons. However, the contribution of the convective heating is important especially in the extended plasma region, where the gas temperature reaches its maximum values up to approximately 1400?K. The temporally and spatially resolved modeling enables a thorough investigation of the plasma-microwave interaction which clearly shows that the power in-coupling occurs in the region of the highest electron density during the early stage of the discharge. In the steady state phase, however, the power in-coupling occurs close to the source walls where the electron density is significantly lower than on the discharge axis.

Baeva, M., E-mail: baeva@inp-greifswald.de; Andrasch, M.; Ehlbeck, J.; Loffhagen, D.; Weltmann, K.-D. [INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

2014-04-14

160

Absorption Spectroscopy Measurements of Ion Velocity Distribution Functions in Argon Plasmas.  

NASA Astrophysics Data System (ADS)

The scarcity of strong absorption lines in accessible tuning ranges along with plasma saturation due to low ion population densities makes absorption spectroscopy of helium ions notoriously difficult. Helicon plasmas, with their characteristically high ion densities, are a good candidate for initial helium ion spectroscopy experiments. However, preliminary measurements of Doppler broadened ion velocity distribution functions (ivdf) involving injecting a tunable infrared diode laser, tuned to 1012.36 nm and chopped roughly at 1kHz, along the axis of a 1.5m long helicon plasma have yielded erratic and irreproducible measurements. Here we present absorption spectroscopy measurements of ivdfs in argon helicon plasma using a tunable diode laser at 668.43 nm to pump the Ar II metastable 3d^4F7/2 level to the 4p^4D5/2 level. The optimized multi-pass optical configuration and the ratioing detector will be described and initial measurements presented. Once the absorption measurement technique is optimized for the well-known and more easily diagnosed Ar II transition, the same experimental configuration will then be used for the infrared helium ion absorption measurement

Scime, Earl; Przybysz, William S.

2007-11-01

161

Comparative analysis of activity of coagulation Factors V and VIII and level of fibrinogen in fresh frozen plasma and frozen plasma  

PubMed Central

Background: The aim of this study was to analyse and compare the activity of factor V, VIII and fibrinogen level in fresh frozen plasma and frozen plasma frozen after 8 hrs but within 24 hours after phlebotomy. Materials and Methods: Fresh frozen plasma separated from whole blood within 8 hours was compared with plasma separated within 24 hours after phlebotomy in terms of coagulation factors V and VIII and level of fibrinogen by standard methods using semi automated coagulometer sysmex CA50. Results: Longer storage of whole blood before processing resulted in significant decrease (18.4%) in activity of factor VIII but the fall in activity of factor V (6.52%) or level of fibrinogen (1.81%) was not significant. Discussion: These data suggest that there is good retention of coagulation factors in both types of plasma. Although there is significant fall in activity of factor VIII, but it is an acute phase reactant and raised in most of the diseases so it is suggested that frozen plasma would be an acceptable product for most patients requiring fresh frozen plasma. PMID:25722564

Dogra, Mitu; Sidhu, Meena; Vasudev, Rahul; Dogra, Ashu

2015-01-01

162

Two-dimensional argon metastable density measurements in a radio frequency plasma reactor by planar laser-induced Jluorescence imaging  

E-print Network

Two-dimensional argon metastable density measurements in a radio frequency plasma reactor by planar-of-sight absorption, or single-point laser-induced fluorescence.iv6 To our knowledge, the only complete two, the measurements cover a wide range of conditions and were performed in a well- characterized reactor (the Gaseous

Zachariah, Michael R.

163

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

164

ANALYSIS OF A WASTEWATER FOR SEVEN PRIORITY POLLUTANT ELEMENTS BY D.C. ARGON PLASMA EMISSION SPECTROSCOPY  

EPA Science Inventory

This limited project was conducted to determine the usefulness of the D.C. argon plasma for the analysis of wastewater. Seven priority pollutant elements, arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), and thallium (Tl), were selected for use i...

165

Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures  

E-print Network

in argon gas at atmospheric pressures Alexander Miloshevsky, Sivanandan S. Harilal, Gennady Miloshevsky formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures. VC plasma expansion into a background gas at atmospheric pressure is cru- cial for many engineering

Harilal, S. S.

166

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

167

Radiative properties of argon–helium–nitrogen–carbon–cobalt–nickel plasmas used in CNT synthesis  

NASA Astrophysics Data System (ADS)

This work presents the radiative properties of argon–helium–nitrogen–carbon–nickel–cobalt thermal plasmas by the computation of net emission coefficients (NECs) under the assumption of a local thermodynamic equilibrium and at temperature range 1000–20?000?K. These mixtures were often used in the study of carbon nanotubes (CNTs) synthesis with arc plasma which becomes one of the most useful techniques in terms of flexibility of carbon nanostructures produced with fewer defects. The values of NEC allow estimation of total radiation losses in plasmas, by taking into account the emission radiation resulting from the atomic continuum, the molecular continuum, the atomic lines and some molecular bands. Free–free transitions (Bremsstrahlung) and free–bound (electron–ion recombination), have been considered for the calculation of atomic continuum. For bound–bound transitions, natural, resonance, Van der Waals, Stark and Doppler effects have been taken into account in the calculation of the lines broadenings while the self-absorption of the resonance lines has been treated using their escape factors. Molecular continuum has been only considered for N2, C2 and CN molecules whereas we have only taken into account diatomic systems N2, \\text{N}2+ , CN and C2 for the emission of the molecular bands. The results obtained show that even for low concentrations of Ni and Co in the plasma, the NECs are modified and considerably increase only at a low temperature (T < 8000?K) and the major contribution in the total radiation arises from the lines emission. However, the effect of the thickness of the plasma on plasma radiation has been analysed based on the self absorption phenomenon of resonance lines.

Salem, D.; Hannachi, R.; Cressault, Y.; Teulet, Ph; Béji, L.

2015-02-01

168

Development of a diffuse air-argon plasma source using a dielectric-barrier discharge at atmospheric pressure  

SciTech Connect

A stable diffuse large-volume air plasma source was developed by using argon-induced dielectric-barrier discharges at atmospheric pressure. This plasma source can be operated in a filamentary discharge with the average areal power density of 0.27 W/cm{sup 2} and the gas temperature of 315{+-}3 K. Spatial measurement of emission spectrum and temperature indicates that this plasma is uniform in the central region along the transverse direction. It is also found that the formation of diffuse air plasma mainly lies in the creation of sufficient seed electrons by the Penning effect through collisions between two argon or nitrogen metastables at low electric fields.

Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China)] [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China); Duan Yixiang [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China) [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China); Research Center of Analytical Instrumentation, Sichuan University, Chengdu 610064 (China)

2013-01-21

169

Effect of dielectric wall temperature on plasma plume in an argon atmospheric pressure discharge  

NASA Astrophysics Data System (ADS)

In this letter, the effect of the dielectric wall temperature on the length and volume of an atmospheric pressure plasma jet (APPJ) is investigated using a single-electrode configuration driven with an AC power supply. To distinguish the APPJ status from the argon flow rate, the three modes, laminar, transition, and turbulent, are separated. When the dielectric wall is heated, the APPJ length and volume are enhanced. Also, the transition regions remarkably expand over a large range of flow rates. The results indicate that different factors contribute to the expansion of the transition region. The increase in the radial and axial velocities is the main cause of the expansion of the transition region to the low-velocity region. The expansion to the high-velocity region is dominantly induced by a change in the viscosity.

Song, Jian; Tang, Jingfeng; Huo, Yuxin; Wei, Liqiu; Wang, Youyin; Yu, Daren

2014-10-01

170

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

SciTech Connect

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.

Mohammadnejad, M.; Pestehe, S. J.; Mohammadi, M. A. [Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Postal Code 5166614766, Tabriz (Iran, Islamic Republic of) [Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Postal Code 5166614766, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2013-07-15

171

Effect of dielectric wall temperature on plasma plume in an argon atmospheric pressure discharge  

SciTech Connect

In this letter, the effect of the dielectric wall temperature on the length and volume of an atmospheric pressure plasma jet (APPJ) is investigated using a single-electrode configuration driven with an AC power supply. To distinguish the APPJ status from the argon flow rate, the three modes, laminar, transition, and turbulent, are separated. When the dielectric wall is heated, the APPJ length and volume are enhanced. Also, the transition regions remarkably expand over a large range of flow rates. The results indicate that different factors contribute to the expansion of the transition region. The increase in the radial and axial velocities is the main cause of the expansion of the transition region to the low-velocity region. The expansion to the high-velocity region is dominantly induced by a change in the viscosity.

Song, Jian; Huo, Yuxin; Wang, Youyin; Yu, Daren, E-mail: yudaren@hit.edu.cn [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Tang, Jingfeng; Wei, Liqiu [Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150001 (China)

2014-10-15

172

Exploring the electron density in plasmas induced by extreme ultraviolet radiation in argon  

E-print Network

The new generation of lithography tools use high energy EUV radiation which ionizes the present background gas due to photoionization. To predict and understand the long term impact on the highly delicate mirrors It is essential to characterize these kinds of EUV-induced plasmas. We measured the electron density evolution in argon gas during and just after irradiation by a short pulse of EUV light at 13.5 nm by applying microwave cavity resonance spectroscopy. Dependencies on EUV pulse energy and gas pressure have been explored over a range relevant for industrial applications. Our experimental results show that the maximum reached electron density depends linearly on pulse energy. A quadratic dependence - caused by photoionization and subsequent electron impact ionization by free electrons - is found from experiments where the gas pressure is varied. This is demonstrated by our theoretical estimates presented in this manuscript as well.

van der Horst, R M; Osorio, E A; Banine, V Y

2015-01-01

173

ATOMIC AND MOLECULAR PHYSICS: Radiative Transition Line Shape in Warm and Dense Argon Plasma: a Two-Centre Model Study  

Microsoft Academic Search

A two-centre model is employed to study the electronic structure of argon plasma at a density of 1022 cm-3 and a temperature of 5eV. The model takes into account the influence of the nearest neighbour on the electronic structure of the radiator and gives a proper description of the transient molecular behaviour in dense plasmas where the mean interatomic distance

Cong-Sen Meng; Zeng-Xiu Zhao; Jian-Min Yuan

2008-01-01

174

Characterization of a low temperature atmospheric-pressure argon microwave induced plasma using visual imaging, OES, and CRDS combined  

Microsoft Academic Search

We employ a suite of optical techniques, visual imaging, optical emission spectroscopy (OES), and cavity ringdown spectroscopy (CRDS), to characterize a low power, low gas flow rates, atmospheric-pressure argon microwave induced plasma (MIP). A series of plasma images captured in a time resolution range of 10 mus-0.05 s shows that the converging point is a visual effect of integrating the

C. Wang; N. Srivastava; S. Scherrer; P. R. Jang; T. S. Dibble; Y. Duan

2009-01-01

175

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

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

Effect of process parameters on properties of argon–nitrogen plasma for titanium nitride film deposition  

SciTech Connect

In this study, the effect of working pressure and input power on the physical properties and sputtering efficiencies of argon–nitrogen (Ar/N{sub 2}) plasma in direct current magnetron discharge is investigated. The discharge in Ar/N{sub 2} is used to deposit TiN films on high speed steel substrate. The physical plasma parameters are determined by using Langmuir probe and optical emission spectroscopy. On the basis of the different reactions in the gas phase, the variation of plasma parameters and sputtering rate are explained. A prominent change of electron temperature, electron density, ion density, and degree of ionization of Ar is found as a function of working pressure and input power. The results also show that increasing working pressure exerts a negative effect on film deposition rate while increasing input power has a positive impact on the same. To confirm the observed physical properties and evaluate the texture growth as a function of deposition parameters, x-ray diffraction study of deposited TiN films is also done.

Saikia, Partha; Kakati, Bharat [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur-782 402, Kamrup, Assam (India)] [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur-782 402, Kamrup, Assam (India)

2013-11-15

178

Pulsed microwave-driven argon plasma jet with distinctive plume patterns resonantly excited by surface plasmon polaritons  

NASA Astrophysics Data System (ADS)

Atmospheric lower-power pulsed microwave argon cold plasma jets are obtained by using coaxial transmission line resonators in ambient air. The plasma jet plumes are generated at the end of a metal wire placed in the middle of the dielectric tubes. The electromagnetic model analyses and simulation results suggest that the discharges are excited resonantly by the enhanced electric field of surface plasmon polaritons. Moreover, for conquering the defect of atmospheric argon filamentation discharges excited by 2.45-GHz of continued microwave, the distinctive patterns of the plasma jet plumes can be maintained by applying different gas flow rates of argon gas, frequencies of pulsed modulator, duty cycles of pulsed microwave, peak values of input microwave power, and even by using different materials of dielectric tubes. In addition, the emission spectrum, the plume temperature, and other plasma parameters are measured, which shows that the proposed pulsed microwave plasma jets can be adjusted for plasma biomedical applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 11105002 and 61170172), the Natural Science Foundation of Anhui Province, China (Grant Nos. 1408085QA16 and 1408085ME101), the China Postdoctoral Science Foundation (Grant No. 2014M551788), and the Open-end Fund of State Key Laboratory of Advanced Electromagnetic Engineering and Technology (HUST), China (Grant No. GZ1301).

Chen, Zhao-Quan; Yin, Zhi-Xiang; Xia, Guang-Qing; Hong, Ling-Li; Hu, Ye-Lin; Liu, Ming-Hai; Hu, Xi-Wei; A. Kudryavtsev, A.

2015-02-01

179

Net emission coefficients of argon iron plasmas with electron Stark widths scaled to experiments  

NASA Astrophysics Data System (ADS)

The net emission coefficient of plasmas containing argon and iron at atmospheric pressure is calculated and analysed for the case of cylindrical geometry. Its values are obtained by integrating the monochromatic net emission coefficient taking into account continuous and line radiation. The width of the spectral lines is determined by Doppler broadening, natural, resonance, van der Waals, electron and ion Stark broadening. As Stark broadening is the most important broadening mechanism in the considered pressure and temperature range, the electron Stark widths are calculated following the semi-empirical Stark broadening theory. Additionally, the electron Stark widths of Ar, Ar+, Fe and Fe+ are multiplied by scaling factors in order to reproduce experimental electron Stark widths. The scaling factor is determined for each species separately. For small plasma radii the net emission coefficient determined here shows good agreement with literature values where spherical geometry is considered while they decrease faster with increasing plasma radius. This behaviour is caused by the increase of the irradiation of the symmetry axis when cylindrical instead of spherical geometry is considered. For radii and temperatures typical of the metal filled core of arcs occurring in gas metal arc welding processes, i.e. radii between 1 and 2 × 10-3 m and temperatures between 5000 and 10 000 K, the scaling of the Stark widths increases the net emission coefficient of iron plasmas by between 2% and 23%. In this parameter range the net emission coefficient of iron plasmas for cylindrical geometry is between 30% and 37% smaller than values calculated for spherical geometry.

Wendt, M.

2011-03-01

180

Characteristics of an atmospheric microwave-induced plasma generated in ambient air by an argon discharge excited in an open-ended dielectric discharge tube  

Microsoft Academic Search

Parametric observations on an atmospheric-pressure plasma sustained in ambient air by an argon discharge excited by 2.45 GHz microwaves in an open-ended dielectric discharge tube are reported. Microwave power, discharge tube dimensions, and argon flow rate were the major operating parameters. Three distinctive plasma regions were observed: plasma filaments exiting from the discharge tube, converging point of these filaments, and

Se Youn Moon; W. Choe; Han S. Uhm; Y. S. Hwang; J. J. Choi

2002-01-01

181

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

182

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

2011-01-01

183

The inactivation of Staphylococcus aureus biofilms using low-power argon plasma in a layer-by-layer approach.  

PubMed

The direct application of low power argon plasma for the decontamination of pre-formed Staphylococcus aureus biofilms on various surfaces was examined. Distinct chemical/physical properties of reactive species found in argon plasmas generated at different wattages all demonstrated very potent but very different anti-biofilm mechanisms of action. An in-depth analysis of the results showed that: (1) the different reactive species produced in each plasma demonstrated specific antibacterial and/or anti-biofilm activity; and (2) the commonly associated etching effect could be manipulated and even controlled, depending on the experimental conditions. Under optimal experimental parameters, bacterial cells in S. aureus biofilms were killed (> 99.9%) by plasmas within 10 min of exposure and no bacteria nor biofilm regrowth from argon discharge gas treated biofilms was observed for 150 h. The decontamination ability of plasmas for the treatment of biofilm related contaminations on various materials was confirmed and an entirely novel layer-by-layer decontamination approach was designed and examined. PMID:25569189

Traba, Christian; Liang, Jun F

2015-01-01

184

Presheath and Double Layer Structures in an Argon Helicon Plasma Source  

NASA Astrophysics Data System (ADS)

Ion velocities and temperatures, plasma density, potential, and electron temperatures are measured in a 13.56 MHz helicon produced argon plasma upstream from a grounded plate inside a 10 cm ID cylindrical Pyrex vacuum chamber. The plate is held at psi = 0° ? 60° relative to the background axial magnetic field in the system. For the psi = 0° experiment, two distinct helicon discharge equilibria are observed at 500 W rf power, 900 G magnetic field, and a neutral pressure of 3 ? 4 mTorr. Both modes exhibit a localized region of hot electrons (Th ? 10 eV, Tc ? 3.5 eV). For the first mode the hot electrons are confined by a localized potential structure and the density decreases monotonically towards the grounded plate. For the second mode the hot electrons cool off gradually in space due to heat conduction generating a downstream density peak and no major potential structures are observed. It is found that the type of discharge mode is determined by the location of the grounded plate, the length of the presheath, and the rf electron heating mechanism. For the psi = 16° ? 60° plate positions, ion flow to the boundary where a 1 kG magnetic field is obliquely incident is measured at 1, 3, and 6.5 mTorr neutral pressure and 450 ? 750 W rf power. The results are compared to the magnetic presheath models put forth by Chodura [Phys. Fluids 25, 1628 (1982)], Riemann [Phys. Plasmas 1, 552 (1994)], and Ahedo [Phys. Plasmas 4, 4419 (1997)]. The 1 mTorr dataset is used to benchmark a one-dimensional fluid model for the ion flow in the presheath. Definitions of the "magnetic presheath" are discussed. The fluid model in conjuction with the data show that the ion velocities in the E x B direction can be 10% ? 40% percent of the sound speed for the angles investigated. Ion flow to fusion experiment boundaries and Hall thruster walls is discussed.

Siddiqui, M. Umair

185

Spatially resolved Langmuir probe diagnostics in a capacitively coupled radio frequency argon and oxygen plasma  

NASA Astrophysics Data System (ADS)

Axial and radial profiles of the positive ion saturation current were measured by Langmuir probe diagnostics in a capacitively coupled radio frequency (RF) plasma in argon and oxygen. Under certain conditions these profiles provide the spatial density distribution of the positive ions, which corresponds approximately to the electron density in the electropositive plasma. Particularly in oxygen at low RF power a peak in the ion saturation current appears in the radial direction at the electrode boundary. The axial position s at the maximum ion saturation current depends on total pressure with s ? p?1/3, which reveals the pressure dependence of a collisional RF sheath. Furthermore, Langmuir probe characteristics were evaluated in terms of the Druyvesteyn method to determine the radial behavior of the electron energy probability function (EEPF). From the EEPF the radially resolved effective electron temperature and electron density were calculated. The radial electron density profile from the Langmuir probe was numerically integrated to calculate a line integrated electron density for comparison with the measured line integrated density from 160 GHz microwave interferometry. The integration over the Langmuir probe density results in a line integrated density, which amounts to 40% of the line integrated density from microwave interferometry.

Küllig, C.; Wegner, Th; Meichsner, J.

2015-02-01

186

Spatio-temporal evolution of the dust particle size distribution in dusty argon rf plasmas  

NASA Astrophysics Data System (ADS)

An imaging Mie scattering technique has been developed to measure the spatially resolved size distribution of dust particles in extended dust clouds. For large dust clouds of micrometre-sized plastic particles confined in an radio frequency (rf) discharge, a segmentation of the dust cloud into populations of different sizes is observed, even though the size differences are very small. The dust size dispersion inside a population is much smaller than the difference between the populations. Furthermore, the dust size is found to be constantly decreasing over time while the particles are confined in an inert argon plasma. The processes responsible for the shrinking of the dust in the plasma have been addressed by mass spectrometry, ex situ microscopy of the dust size, dust resonance measurements, in situ determination of the dust surface temperature and Fourier transform infrared absorption (FT-IR). It is concluded that both a reduction of dust size and its mass density due to outgassing of water and other volatile constituents as well as chemical etching by oxygen impurities are responsible for the observations.

Killer, Carsten; Mulsow, Matthias; Melzer, André

2015-04-01

187

Mechanism of forward development of a plasma produced by an excimer laser in high-pressure argon gases  

NASA Astrophysics Data System (ADS)

In high-pressure argon gases up to 150 atm, the plasma produced by a XeCl excimer laser developed not only backward but also forward. The model for the forward development, called a forward breakdown wave, could not predict the developmental behavior in the latter stage. The development model was modified, newly taking into account the laser absorption by the plasma when the laser light was transmitted through the backward plasma. The time variation of the absorption coefficient at each distance was calculated using the inverse bremsstrahlung by the electron-ion impact. This modified model could better predict the forward development behavior than the previous model.

Tsuda, Norio; Yamada, Jun

2000-03-01

188

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

NASA Astrophysics Data System (ADS)

This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N2-Ar and O2-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 N2-Ar and O2-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 N2-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 O2 -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 O2-Ar discharges, the dissociation fraction of O2 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.

2011-06-01

189

Predicting the presence of plasma heparin using neural networks to analyze coagulation screening assay optical profiles.  

PubMed

A method for predicting the presence of heparin from coagulation screening assays is described and data are presented. This method incorporates the use of a multilayer perceptron trained through an error back-propagation algorithm in analyzing clotting optical data profiles. This method may lead to the identification of abnormalities from screening assays that might otherwise go undetected, or require additional testing to isolate. PMID:8997540

Givens, T B; Braun, P; Fischer, T J

1996-11-01

190

X-ray Photoelectron Spectroscopy Study of Argon-Plasma-Treated Fluoropolymers  

NASA Technical Reports Server (NTRS)

Films of poly(tetrafluoroethylene) (PTFE) and of a tetrafluoroethylene-perfluoroalkyl vinyl ether (approximately 49:1) copolymer (PFA) were exposed to a radio-frequency argon plasma and then examined by X-ray photoelectron spectroscopy (XPS). The use of fluoropolymer films nearly free of surface hydrocarbon contamination as well as the use of a monochromatized X-ray source for XPS removed two factors contributing to conflicting reports on the effect of exposure time on the fluorine-to-carbon (F/C) and oxygen-to-carbon (O/C) ratios for several Ar-plasma-treated fluoropolymers. Contrary to literature indications, a common pattern was found for PTFE and PFA: a moderate decrease in F/C ratio (from 1.99 to 1.40, and from 1.97 to 1.57, respectively), together with a moderate increase in O/C ratio (from negligible to about 0.10, and from 0.012 to about O.10, respectively) at very short exposures, after which the F/C ratios remained essentially constant on prolonged exposures, while the O/C ratios for PTFE and PFA leveled off at 0.11 and 0.15, respectively. The XPS C(sub 1s), spectra for these polymers exposed to the Ar plasma for 20 min were similar and presented, besides a prominent peak at 292.0 eV (CF2,) and a minor peak at 294.0 or 294.1 eV (CF3), a composite band of four curve-resolved peaks (approximately 285-290 eV) representing various CH, CC, CO, CN, and CF functionalities.

Golub, Morton A.; Lopata, Eugene S.; Finney, Lorie S.

1994-01-01

191

Plasma/particle interaction in subsonic argon/helium thermal plasma jets  

SciTech Connect

Understanding the behavior of a particle and the interactions between a particle and the plasma surrounding it is important to the development and optimization of the plasma spray coating process. This is an experimental study of the interaction between a subsonic thermal plasma jet and injected nickel-aluminum particles. The velocity, temperature and composition of the gas flow field is mapped using an enthalpy probe/mass spectrometer system. The particle flow field is examined by simultaneously measuring the in-flight size, velocity, and temperature of individual particles. The complex interaction between the gas and particle flow fields is examined by combining the two sets of data. Particle and gas temperatures and velocities are compared in the vicinity of a nominal substrate standoff distance and axially along the median particle trajectory. The temperature and velocity difference is shown to vary substantially depending on the particle`s trajectory. By the time a particle on the median trajectory reaches the nominal substrate stand off of 63.5 mm it is transferring it`s heat and momentum to the plasma gas.

Swank, W.D.; Fincke, J.R.; Haggard, D.C.

1993-04-01

192

Plasma/particle interaction in subsonic argon/helium thermal plasma jets  

SciTech Connect

Understanding the behavior of a particle and the interactions between a particle and the plasma surrounding it is important to the development and optimization of the plasma spray coating process. This is an experimental study of the interaction between a subsonic thermal plasma jet and injected nickel-aluminum particles. The velocity, temperature and composition of the gas flow field is mapped using an enthalpy probe/mass spectrometer system. The particle flow field is examined by simultaneously measuring the in-flight size, velocity, and temperature of individual particles. The complex interaction between the gas and particle flow fields is examined by combining the two sets of data. Particle and gas temperatures and velocities are compared in the vicinity of a nominal substrate standoff distance and axially along the median particle trajectory. The temperature and velocity difference is shown to vary substantially depending on the particle's trajectory. By the time a particle on the median trajectory reaches the nominal substrate stand off of 63.5 mm it is transferring it's heat and momentum to the plasma gas.

Swank, W.D.; Fincke, J.R.; Haggard, D.C.

1993-01-01

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

Dynamical Domain Tabular Collisional Radiative Equilibrium Radiation Transport Model for Argon Gas-Puff Z-Pinch Plasmas  

Microsoft Academic Search

Summary form only given. The proper treatment of the radiation transport in the multidimensional MHD simulations of large diameter argon gas-puff Z-pinch loads is essential in understanding and predicting accurately the dynamic evolution and the radiative emission characteristics of the plasmas. The tabular collisional radiative equilibrium (TCRE) radiation transport model represents a novel approach to the realistic self-consistent treatment of

Y. K. Chong; J. W. Thornhill; J. P. Apruzese; J. Davis; H. D. Minor

2005-01-01

195

Liquid crystal alignment on aC:H films by an argon plasma jet at atmospheric pressure  

Microsoft Academic Search

A novel liquid crystal alignment method has been successfully developed. The alignment layer was made of a hydrogenated amorphous carbon film (a-C:H). At atmospheric pressure, the surface of the film was treated by a low temperature argon plasma jet. Experimental results showed that uniform alignment of the liquid crystal (ZLI-2293) has been achieved with a pretilt angle of 2.32° in

H. K. Wei; C. S. Kou; K. Y. Wu; J. Hwang

2008-01-01

196

A collisional-radiative model including radiation trapping and transport phenomena for diagnostics of an inductively coupled argon plasma  

NASA Astrophysics Data System (ADS)

The collisional-radiative model including radiation trapping and transport phenomena along with electron impact and radiative processes has been extended to the actual argon ICP, i.e. structural and inhomogeneous. The electron temperature ( Te), which is an essential plasma parameter for the collisional-radiative model, was measured from the background continuum without assuming the thermal equilibrium between the higher excited atomic levels and the ionic ground state. Observed Te at the height of 15 mm above the load coil was 8400 K, which was rather lower compared with the literature values determined from the ratio of Ar emission line and continuum in a 40-MHz ICP, while the electron number density was approx. twice larger. The calculated population number densities showed close values to LTE, because the radiation trapping, not only for the resonance lines but also for non-resonance lines, compensated for the overpopulation of low lying levels which might be caused by spontaneous emission. The transport effect of species was negligible in the normal analytical region. In the coaxial zone around 5 mm above the load coil and in the tail flame of the plasma, however, the large inflow of electrons and ions by ambipolar diffusion or convection reduced the number density of argon neutral atoms, where the argon ICP can be denned as a recombining plasma.

Hasegawa, Tetsuya; Haraguchi, Hiroki

197

Integrated parametric study of a hybrid-stabilized argon-water arc under subsonic, transonic and supersonic plasma flow regimes  

NASA Astrophysics Data System (ADS)

This paper presents a numerical investigation of characteristics and processes in the worldwide unique type of thermal plasma generator with combined stabilization of arc by argon flow and water vortex, the so-called hybrid-stabilized arc. The arc has been used for spraying of ceramic or metallic particles and for pyrolysis of biomass. The net emission coefficients as well as the partial characteristics methods for radiation losses from the argon-water arc are employed. Calculations for 300-600 A with 22.5-40 standard litres per minute (slm) of argon reveal transition from a transonic plasma flow for 400 A to a supersonic one for 600 A with a maximum Mach number of 1.6 near the exit nozzle of the plasma torch. A comparison with available experimental data near the exit nozzle shows very good agreement for the radial temperature profiles. Radial velocity profiles calculated 2 mm downstream of the nozzle exit show good agreement with the profiles determined from the combination of calculation and experiment (the so-called integrated approach). A recent evaluation of the Mach number from the experimental data for 500 and 600 A confirmed the existence of the supersonic flow regime.

Jeništa, J.; Takana, H.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; K?enek, P.; Hrabovský, M.; Kavka, T.; Sember, V.; Mašláni, A.

2011-11-01

198

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

199

Sputtering rates of lead chalcogenide-based ternary solid solutions during inductively coupled argon plasma treatment  

NASA Astrophysics Data System (ADS)

In this work investigations of sputtering of monocrystalline (1 1 1)-oriented epitaxial films of semiconductor ternary solid solutions of Pb1-xSnxTe (x = 0.00-0.56), Pb1-xEuxTe (x = 0.00-0.05), Pb1-xSnxSe (x = 0.00-0.07), Pb1-xEuxSe (x = 0.00-0.16, x = 1.00), Pb1-xSnxS (x = 0.00-0.05) on Si(1 1 1) and BaF2(1 1 1) substrates in RF high-density low-pressure inductively coupled argon plasma were carried out. It is determined that sputtering rates for the studied materials retain high values typical for binary solutions PbTe, PbSe, PbS. The results indicate the interrelation of the sputtering rates of ternary compounds and of the sublimation energy of binary compounds that constitute a solid solution. The physical model of this characteristic property of lead chalcogenide-based ternary alloys based on the expansion of a classic Sigmund solid sputtering theory explaining the observed sputtering rate behavior with the alloy composition variation is proposed.

Zimin, S. P.; Gorlachev, E. S.; Amirov, I. I.; Zogg, H.; Abramof, E.; Rappl, P. H. O.

2011-10-01

200

[Trimming with argon plasma of self-expanding metal stents: report of 7 cases].  

PubMed

The use of self-expandable enteral stents for palliation of malignant stenosis may present the complication of concealing the ampulla of Vater behind the metallic mesh. Anchoring in the duodenal wall (distal or partial migration) may also be a complication of biliary metallic stents and therefore may cause difficulty in gaining access to the biliary tract. In these cases of difficult access, a fenestration on the prosthesis ( biliary or enteral) can be created to allow reaching the obstructed biliary tract by means of argon plasma (AP). Were retrospectively analysed 7 cases. Under endoscopic vision, AP was directed to filgurate and cut 6 biliary prosthesis and a duodenal stent. Fulguration and cut of biliary stent was performed in 5 cases of distal partial migration and cholangitis. In one case of obstruction caused by distal migration inside the duodenal stent light, cutting of the biliary stent was performed. A window was created in the enteral prosthesis in order to access the ampulla of Vater and place a biliary tract prosthesis. All cases were resolved successfully and without complications. We conclude that the use of AP to fulgurate and cut nitinol prosthesis was effective and presented no complications in this series. PMID:25199306

Jury, Gastón; Amieva, Leandro; López, Fagalde Rafael; Jury, Rubén

2014-06-01

201

Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet  

SciTech Connect

In present study, a pulsed lower-power microwave-driven atmospheric-pressure argon plasma jet has been introduced with the type of coaxial transmission line resonator. The plasma jet plume is with room air temperature, even can be directly touched by human body without any hot harm. In order to study ionization process of the proposed plasma jet, a self-consistent hybrid fluid model is constructed in which Maxwell's equations are solved numerically by finite-difference time-domain method and a fluid model is used to study the characteristics of argon plasma evolution. With a Guass type input power function, the spatio-temporal distributions of the electron density, the electron temperature, the electric field, and the absorbed power density have been simulated, respectively. The simulation results suggest that the peak values of the electron temperature and the electric field are synchronous with the input pulsed microwave power but the maximum quantities of the electron density and the absorbed power density are lagged to the microwave power excitation. In addition, the pulsed plasma jet excited by the local enhanced electric field of surface plasmon polaritons should be the discharge mechanism of the proposed plasma jet.

Chen, Zhaoquan, E-mail: zqchen@aust.edu.cn [Faculty of Physics, St. Petersburg State University, St. Petersburg 198504 (Russian Federation); College of Electrical and Information Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Yin, Zhixiang, E-mail: zxyin66@163.com; Chen, Minggong; Hong, Lingli; Hu, Yelin; Huang, Yourui [College of Electrical and Information Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Xia, Guangqing; Liu, Minghai [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Kudryavtsev, A. A. [Faculty of Physics, St. Petersburg State University, St. Petersburg 198504 (Russian Federation)

2014-10-21

202

Experimental investigation of argon metastable density and electron temperature in low-pressure plasma by line-ratio OES technique  

NASA Astrophysics Data System (ADS)

The measurement of metastable atom densities and electron temperatures are performed in inductively coupled plasma (ICP) source (13.56 MHz) combined with biased electrode (12.5 MHz), in pure argon or in mixtures of N2. The argon metastable densities and electron temperatures are derived under the different discharge conditions, i.e., E-H mode transition, rf power biasing and Ar-N2 mixtures. The observation of certain argon spectral lines (750.4, 751.5 and 811.5 nm) is made with optical emission spectroscopy (OES) at the pressure of 50 and 100 mTorr. In the same plasma conditions, rf-compensated Langmuir probe is used to measure the electron energy distribution functions (EEDFs) that provides the accurate rate coefficients to calculate the line-ratio OES method. It is found that the 1s5 metastable density was found to be the highest concentration at mode transition region but it decreases with increasing rf bias power or mixing ratio of N2. The measurements of electron temperature measured by line-ratio OES and probe confirmed that electron temperature was relatively uniform at mode transition but it increases with increasing rf bias power or mixing ratio of N2.

Lee, Young-Kwang; Kim, Yu-Sin; Lee, Jae-Won; Hwang, Hye-Ju; Chung, Chin-Wook

2011-11-01

203

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

204

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

NASA Astrophysics Data System (ADS)

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.

2011-02-01

205

Single-shot Thomson scattering on argon plasmas created by the Microwave Plasma Torch; evidence for a new plasma class  

Microsoft Academic Search

To determine the fine-structure size of plasmas created by a Microwave Plasma Torch (MPT), single-shot Thomson scattering (TS) measurements were performed. The aim was to find a solution for the long-standing discrepancy between experiments and Global Plasma Models (GPMs). Since these GPMs are based on the assumption that (ambipolar) diffusion is the main loss process for charged particles, the diffusion

J. J. A. M. van der Mullen; M. J. van de Sande; N. de Vries; BHP Broks; EI Iordanova; A. Gamero; J. Torres; A. Sola

2007-01-01

206

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

207

Selective depletion of plasma prekallikrein or coagulation factor XII inhibits thrombosis in mice without increased risk of bleeding.  

PubMed

Recent studies indicate that the plasma contact system plays an important role in thrombosis, despite being dispensable for hemostasis. For example, mice deficient in coagulation factor XII (fXII) are protected from arterial thrombosis and cerebral ischemia-reperfusion injury. We demonstrate that selective reduction of prekallikrein (PKK), another member of the contact system, using antisense oligonucleotide (ASO) technology results in an antithrombotic phenotype in mice. The effects of PKK deficiency were compared with those of fXII deficiency produced by specific ASO-mediated reduction of fXII. Mice with reduced PKK had ? 3-fold higher plasma levels of fXII, and reduced levels of fXIIa-serpin complexes, consistent with fXII being a substrate for activated PKK in vivo. PKK or fXII deficiency reduced thrombus formation in both arterial and venous thrombosis models, without an apparent effect on hemostasis. The amount of reduction of PKK and fXII required to produce an antithrombotic effect differed between venous and arterial models, suggesting that these factors may regulate thrombus formation by distinct mechanisms. Our results support the concept that fXII and PKK play important and perhaps nonredundant roles in pathogenic thrombus propagation, and highlight a novel, specific and safe pharmaceutical approach to target these contact system proteases. PMID:21821705

Revenko, Alexey S; Gao, Dacao; Crosby, Jeff R; Bhattacharjee, Gourab; Zhao, Chenguang; May, Chris; Gailani, David; Monia, Brett P; MacLeod, A Robert

2011-11-10

208

Mitigation of carbon erosion in beryllium seeded deuterium plasma under bombardment by argon and helium ions in PISCES-B  

NASA Astrophysics Data System (ADS)

The influence of argon and helium impurities on chemical erosion of carbon by deuterium and on the mitigation of erosion by the beryllium seeding has been studied in the PISCES-B linear plasma device. Optical spectroscopy has been used to quantify the amounts of Be, Ar and He in the deuterium plasma and to monitor the reduction of the CD band as a measure of carbon chemical erosion of the fine-grain graphite target. The addition of Ar and He has not resulted in an increase of the carbon erosion rate. Moreover, the characteristic time for the Be layer formation was in agreement with the reference exposures. It can be concluded, that for the covered range of experimental parameters the addition of Ar and He to plasma does not affect the formation of the protective Be carbide layer and the associated mitigation of carbon erosion.

Kreter, A.; Nishijima, D.; Baldwin, M. J.; Doerner, R. P.; Pospieszczyk, A.

2011-10-01

209

Kinetic modeling of evolution of 3?+?1:Resonance enhanced multiphoton ionization plasma in argon at low pressures  

SciTech Connect

We present numerical kinetic modeling of generation and evolution of the plasma produced as a result of resonance enhanced multiphoton ionization (REMPI) in Argon gas. The particle-in-cell/Monte Carlo collision (PIC/MCC) simulations capture non-equilibrium effects in REMPI plasma expansion by considering the major collisional processes at the microscopic level: elastic scattering, electron impact ionization, ion charge exchange, and recombination and quenching for metastable excited atoms. The conditions in one-dimensional (1D) and two-dimensional (2D) formulations correspond to known experiments in Argon at a pressure of 5?Torr. The 1D PIC/MCC calculations are compared with the published results of local drift-diffusion model, obtained for the same conditions. It is shown that the PIC/MCC and diffusion-drift models are in qualitative and in reasonable quantitative agreement during the ambipolar expansion stage, whereas significant non-equilibrium exists during the first few 10?s of nanoseconds. 2D effects are important in the REMPI plasma expansion. The 2D PIC/MCC calculations produce significantly lower peak electron densities as compared to 1D and show a better agreement with experimentally measured microwave radiation scattering.

Tholeti, Siva Sashank; Alexeenko, Alina A., E-mail: alexeenk@purdue.edu [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Shneider, Mikhail N. [Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2014-06-15

210

The effect of radio-frequency self bias on ion acceleration in expanding argon plasmas in helicon sources  

NASA Astrophysics Data System (ADS)

Time-averaged plasma potential differences up to ˜ 165 V over several hundred Debye lengths are observed in low pressure (pn < 1 mTorr) expanding argon plasmas in the Madison Helicon Experiment. The potential gradient leads to ion acceleration exceeding Ei ? 7 kTe in some cases. Up to 1 kW of 13.56 MHz RF power is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field up to 1 kG. An RPA measures the IEDF and an emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, are identified by jumps in electron density as RF power is increased. In the capacitive mode, large fluctuations of the plasma potential (Vp--p ? 140 V, Vp--p/Vp ? 150%) exist at the RF frequency, leading to formation of a self-bias voltage. The mobile electrons can flow from the upstream region during an RF cycle whereas ions cannot, leading to an initial imbalance of flux, and the self-bias voltage builds as a result. The plasma potential in the expansion chamber is held near the floating potential for argon (Vp ? 5kTe/e). In the capacitive mode, the ion acceleration is not well described by an ambipolar relation. The accelerated population decay is consistent with that predicted by charge-exchange collisions. Grounding the upstream endplate increases the self-bias voltage compared to a floating endplate. In the inductive and helicon modes, the ion acceleration more closely follows an ambipolar relation, a result of decreased capacitive coupling due to the decreased RF skin depth. The scaling of the potential gradient with the argon flow rate, magnetic field and RF power are investigated, with the highest potential gradients observed for the lowest flow rates in the capacitive mode. The magnitude of the self-bias voltage agrees well with that predicted for RF sheaths. Use of the self-bias effect in a plasma thruster is explored, possibly for a low thrust, high specific impulse mode in a multi-mode helicon thruster. This work could also explain similar potential gradients in expanding helicon plasmas that are ascribed to double layer formation in the literature.

Wiebold, Matthew D.

211

Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restoration  

PubMed Central

The objective of this study is to investigate the treatment effects of non-thermal atmospheric gas plasmas on dentin surfaces for composite restoration. Extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. The dentin surfaces were treated by using a non-thermal atmospheric argon plasma brush for various durations. The molecular changes of the dentin surfaces were analyzed using FTIR/ATR and an increase in carbonyl groups on dentin surfaces was detected with plasma treated dentin. Adper Single Bond Plus adhesive and Filtek Z250 dental composite were applied as directed. To evaluate the dentin/composite interfacial bonding, the teeth thus prepared were sectioned into micro-bars as the specimens for tensile test. Student Newman Keuls tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment. However, the bonding strength to plasma treated inner dentin did not show any improvement. It was found that plasma treatment of peripheral dentin surface up to 100 s gave an increase in interfacial bonding strength, while a prolong plasma treatment of dentin surfaces, e.g., 5 min treatments, showed a decrease in interfacial bonding strength. PMID:20831586

Ritts, Andy Charles; Li, Hao; Yu, Qingsong; Xu, Changqi; Yao, Xiaomei; Hong, Liang; Wang, Yong

2010-01-01

212

Effects of heating coagulation of middle meningeal artery on plasma CGRP level and c-fos expression in migraine rat triggered by nitroglycerin.  

PubMed

Current theory or hypothesis relevant to migraine indicates that trigeminovascular system plays a pivotal role in the pathophysiology of migraine. Particularly, release of neuropeptide and induction of c-fos like immunoreactivity (c-fos LI) within trigeminal nucleus caudalis neurons are regarded as activation markers of trigeminovascular system. In the present study, we set up a rat model for migraine triggered by nitroglycerin (NTG) and coagulated the middle meningeal artery by heating. Using this model, we determined the plasma calcitonin gene-related peptide (CGRP) level as well as the expression of c-fos in trigeminal nucleus caudalis of rats. We found that NTG led to markedly increase in plasma CGRP level and c-fos expression in trigeminal nucleus caudalis compared with the isotonic saline-treated group (P < 0.05). More importantly, heat coagulation of middle meningeal artery could decrease plasma CGRP level and c-fos expression in trigeminal nucleus caudalis (P < 0.05). Heat coagulation of middle meningeal artery may ameliorate sufferings of rat induced by NTG and play an important role in restraining the release of CGRP as well as the activation of neurons in trigeminal nucleus caudalis in rats following NTG infusion. PMID:21331665

Zhu, Xiaofeng; Han, Yuechen; Xiong, Wenping; Liu, Wenwen; Lu, Sumei; Li, Jianfeng; Wang, Haibo; Fan, Zhaomin

2011-08-01

213

Thermophysical properties of carbon-argon and carbon-helium plasmas  

Microsoft Academic Search

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

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

2011-01-01

214

Real-time analysis of metals in stack gas using argon/air inductively coupled plasma with optical emission spectrometry  

NASA Astrophysics Data System (ADS)

The design and operation of an instrument capable of continuous, real-time detection of hazardous air pollutant metals in the effluent of boilers, incinerators, and furnaces is reported. A commercially available inductively coupled argon plasma spectrometer, modified for introduction of sample air, provides sensitivity for several metals comparable to that of EPA-approved manual methods, with an analysis result reported every 1 to 2 minutes. Achievable detection limits for the present list of hazardous air pollutant metals range from 0.1 to 20 (mu) g/dry standard cubic meter. Air is isokinetically extracted from a stack or duct and introduced into the argon plasma through an innovative sample transport interface. Data is reported after every measurement cycle and immediately archived to a control computer, where the information is available to a local area network. The entire instrument is automated, and is enclosed in a shelter that can be placed as near as possible to the stack. The measurement of sample losses in the transport line is also discussed.

Meyer, Gerhard; Seltzer, Michael D.

1999-02-01

215

Determination of dissolved boron in fresh, estuarine, and geothermal waters by d.c. argon-plasma emission spectrometry  

USGS Publications Warehouse

A d.c. argon-plasma emission spectrometer is used to determine dissolved boron in natural (fresh and estuarine) water samples. Concentrations ranged from 0.02 to 250 mg l-1. The emission-concentration function is linear from 0.02 to 1000 mg l-1. Achievement of a relative standard deviation of ??? 3% requires frequent restandardization to offset sensitivity changes. Dilution may be necessary to overcome high and variable electron density caused by differences in alkali-metal content and to avoid quenching of the plasma by high solute concentrations of sodium and other easily ionized elements. The proposed method was tested against a reference method and found to be more sensitive, equally or more precise and accurate, less subject to interferences, with a wider linear analytical range than the carmine method. Analyses of standard reference samples yielded results in all cases within one standard deviation of the means. ?? 1978.

Ball, J.W.; Thompson, J.M.; Jenne, E.A.

1978-01-01

216

VOLUME 82, NUMBER 4 P H Y S I C A L R E V I E W L E T T E R S 25 JANUARY 1999 Spectroscopic Measurements of Argon Plasma Formation  

E-print Network

Measurements of Argon Plasma Formation by a High-Intensity Lithium Ion Beam J. E. Bailey,1 H. K. Chung,2 A. L of plasma formation by a 20 nsec, 9 MeV, 20 kA cm2 Li13 ion beam injected into 2-Torr argon, conditions II, must be accounted for to achieve accu- rate predictions of the argon ionization kinetics. Light

Cohen, David

217

The study of a homogeneous column of argon plasma at a pressure of 0.5 torr, generated by means of the Beenakker's cavity  

NASA Astrophysics Data System (ADS)

A homogeneous column of argon plasma at a pressure of 0.5 torr, generated by means of the Beenakker cavity, has been investigated by methods of emission spectroscopy, photography and self-consistent 3D modeling in a nonlocal approximation. It is shown that the plasma column, which spreads beyond the resonator, is spatially uniform and it represents the afterglow of the microwave discharge produced inside the cavity. The simulation data of the spatial distributions of the electron energy density and concentrations of electrons, ions and argon atoms in metastable and radiating states are presented. The results of calculations are in agreement with experimental data.

Epstein, Irene L.; Gavrilovi?, Marijana; Jovi?evi?, Sonja; Konjevi?, Nikola; Lebedev, Yuri A.; Tatarinov, Alexey V.

2014-11-01

218

Ion Transport Measurements in a Multi-Dipole Argon Plasma by Broadband Laser Induced Fluorescence  

Microsoft Academic Search

Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar(II) 3d4F7\\/2 to 4p4D05\\/2. The intensity of the induced fluorescence at 442 nm was maximized by the optimization of the discharge parameters and the laser power. From the

Jinlin Xie; Zhi Yu; Wandong Liu; Changxuan Yu

2009-01-01

219

Evaluation of bone response to synthetic bone grafting material treated with argon-based atmospheric pressure plasma.  

PubMed

Bone graft materials are utilized to stimulate healing of bone defects or enhance osseointegration of implants. In order to augment these capabilities, various surface modification techniques, including atmospheric pressure plasma (APP) surface treatment, have been developed. This in vivo study sought to assess the effect of APP surface treatment on degradation and osseointegration of Synthograft™, a beta-tricalcium phosphate (?-TCP) synthetic bone graft. The experimental (APP-treated) grafts were subjected to APP treatment with argon for a period of 60s. Physicochemical characterization was performed by environmental scanning electron microscopy, surface energy (SE), and x-ray photoelectron spectroscopy analyses both before and after APP treatment. Two APP-treated and two untreated grafts were surgically implanted into four critical-size calvarial defects in each of ten New Zealand white rabbits. The defect samples were explanted after four weeks, underwent histological analysis, and the percentages of bone, soft tissue, and remaining graft material were quantified by image thresholding. Material characterization showed no differences in particle surface morphology and that the APP-treated group presented significantly higher SE along with higher amounts of the base material chemical elements on it surface. Review of defect composition showed that APP treatment did not increase bone formation or reduce the amount of soft tissue filling the defect when compared to untreated material. Histologic cross-sections demonstrated osteoblastic cell lines, osteoid deposition, and neovascularization in both groups. Ultimately, argon-based APP treatment did not enhance the osseointegration or degradation of the ?-TCP graft. Future investigations should evaluate the utility of gases other than argon to enhance osseointegration through APP treatment. PMID:25491854

Beutel, Bryan G; Danna, Natalie R; Gangolli, Riddhi; Granato, Rodrigo; Manne, Lakshmiprada; Tovar, Nick; Coelho, Paulo G

2014-12-01

220

On the difference between breakdown and quench voltages of argon plasma and its relation to 4p-4s atomic state transitions  

NASA Astrophysics Data System (ADS)

Using a relaxation oscillator circuit, breakdown (VBD) and quench (VQ) voltages of a DC discharge microplasma between two needle probes are measured. High resolution modified Paschen curves are obtained for argon microplasmas including a quench voltage curve representing the voltage at which the plasma turns off. It is shown that for a point to point microgap (e.g., the microgap between two needle probes) which describes many realistic microdevices, neither Paschen's law applies nor field emission is noticeable. Although normally VBD > VQ, it is observed that depending on environmental parameters of argon, such as pressure and the driving circuitry, plasma can exist in a different state with equal VBD and VQ. Using emission line spectroscopy, it is shown that VBD and VQ are equal if the atomic excitation by the electric field dipole moment dominantly leads to one of the argon's metastable states (4P5 in our study).

Forati, Ebrahim; Piltan, Shiva; Sievenpiper, Dan

2015-02-01

221

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon  

NASA Astrophysics Data System (ADS)

Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (?max = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/ N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10-15 m3/s.

Malinina, A. A.; Malinin, A. N.

2015-03-01

222

Study of a microwave induced argon plasma sustained in a TE 101 cavity as spectrochemical emission source coupled with graphite furnace evaporation  

Microsoft Academic Search

The argon MIP sustained in a TE101 cavity has been evaluated as a spectrochemical radiation source and its analytical performance in combination with graphite furnace evaporation has been studied. A quartz discharge tube with a side arm is used, through which the sample vapour from the furnace is introduced by the carrier gas. A stable quasi-toroidal rotating plasma with a

Jinfu Yang; Jingyu Zhang; C. Schickling; J. A. C. Broekaert

1996-01-01

223

Experimental and Theoretical Analysis of Argon Plasma-Enhanced Quantum-Well Intermixing  

Microsoft Academic Search

Plasma-enhanced quantum-well intermixing (QWI) has been developed for tuning the bandgap of InGaAs-InP ma- terial using an inductively coupled plasma system. The applica- tion of inductively coupled plasma enhances the interdiffusion of point defects resulting in a higher degree of intermixing. Based on a semi-empirical model of QW interdiffusion, the bandgap blue-shift with respect to the plasma exposure time and

H. S. Djie; T. Mei; J. Arokiaraj; C. Sookdhis; S. F. Yu; L. K. Ang; X. H. Tang

2004-01-01

224

Change in Graphite Structure and Properties on Exposure to Pulsed Argon, Hydrogen, and Methane Plasma  

Microsoft Academic Search

We studied the changes in the structure and properties of carbon materials on exposure to a capacitor discharge pulsed plasma with the following parameters: temperature, ~(50–60) × 10 3 K; pulse duration, ~100– 150 µ s. The plasma was generated using a setup consisting of a charge circuit, a capacity storage, and a plasma reactor. After the breakdown voltage (5?10

Academician A. V. Elyutin; I. V. Blinkov

2004-01-01

225

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

USGS Publications Warehouse

Inductively coupled argon plasma/optical emission spectrometery (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 by a nitric acid gradient cation exchange and hydrochloric acid anion exchange. Precision of 1-4% relative standard deviation and comparable accuracy are demonstrated by the triplicate analysis of three splits of BCR-1 and BHVO-1. Analyses of other geological materials including coals, soils, and rocks show comparable precision and accuracy.

Crock, J.G.; Lichte, F.E.

1982-01-01

226

The antibacterial activity of a microwave argon plasma jet at atmospheric pressure relies mainly on UV-C radiations  

NASA Astrophysics Data System (ADS)

The main bactericidal sources produced by a microwave induced cold argon plasma jet in open air are identified and their relative proportion in the biocide efficiency of the jet is assessed on planktonic Gram-negative bacteria (wild-type strains and deletion mutants of Escherichia coli) diluted in water. In these conditions ultraviolet light (UV) most probably in the UV-C region of the electromagnetic spectrum, is responsible for 86.7 ± 3.2% of the observed bactericidal efficiency of the jet whereas hydrogen peroxide represents 9.9 ± 5.5% of it. The exposition level of the bacteria to UV-C radiations is estimated at 20 mJ cm-2 using a specific photodiode and the influence of the initial bacteria concentration on the apparent antibacterial efficiency of the jet is highlighted.

Judée, F.; Wattieaux, G.; Merbahi, N.; Mansour, M.; Castanié-Cornet, M. P.

2014-10-01

227

Possibilities of determining non-Maxwellian EEDFs from the OES line-ratios in low-pressure capacitive and inductive plasmas containing argon and krypton  

NASA Astrophysics Data System (ADS)

Optical emission spectroscopy (OES) is classically used to determine the electron temperature in low-temperature plasmas by assuming a Maxwellian electron energy distribution function (EEDF). However, non-Maxwellian EEDFs are often found in these plasmas. In this work, we propose an OES line-ratio method that is aimed at obtaining non-Maxwellian EEDFs, with a collisional-radiative model of argon and krypton. When applied for both a capacitively coupled plasma and an inductively coupled plasma, this method provides satisfactory results compared with those measured using a Langmuir probe.

Zhu, Xi-Ming; Pu, Yi-Kang; Celik, Yusuf; Siepa, Sarah; Schüngel, Edmund; Luggenhölscher, Dirk; Czarnetzki, Uwe

2012-04-01

228

Time-resolved RF-driven probe measurements of the plasma parameters in a pulsed RF argon discharge  

NASA Astrophysics Data System (ADS)

This paper describes a three-harmonic active probe compensation technique, developed for obtaining time-resolved plasma parameter measurements in pulsed, low-pressure, RF discharges. Using a sample-and-hold circuit, the amplitude and phase of the compensation signals fed to the probe tip are tuned so that at each time point of the measurement, a maximum in the probe floating potential is achieved. The technique allows the accurate determination of the plasma parameters in transient phases of the discharge pulse (when the RF exciting voltage ramps up between 'off' and 'on' phases), not possible when the feedback signals are tuned for continuous wave (CW) operation. Comparison between this point-wise technique and CW tuning of the compensation signals has been carried out in a 1.3 Pa pressure argon discharge pulsed at frequencies between 200 and 2000 Hz. With tuning made in CW operation, the floating potentials are underestimated by about 10 V at the beginning of a pulse, while the electron temperature and plasma density are overestimated by a factor of 2, compared to the point-wise measurements. In the quiescent phases of the pulse (~100 µs after initiation), however, the two methods agree well.

Voronin, S.; Alexander, M.; Bradley, J. W.

2004-12-01

229

Influence of Electron and Excited States Densities on the Electron Energy Distribution Function of Argon Microwave Plasmas  

Microsoft Academic Search

A new set of electron cross-sections for argon has been compiled from a review of former sets and by using results published up to date (2004). The new set proposed has been tested by comparing calculated argon transport coefficients and swarm parameters with experimental values available, and has been used to develop a 32 level collisional-radiative model for argon. This

A. Yanguas-Gil; J. Cotrino; L. L. Alves

2004-01-01

230

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

231

Numerical Simulation of Flow in the Chamber of the Water-Argon Plasma Generator  

NASA Astrophysics Data System (ADS)

The paper describes the CFD simulation of the flow of gas and plasma in a plasma generator with a hybrid stabilization of the electric arc. The momentum equations of the model also take Lorentz forces into account. In the energy equation, Joule heat is introduced as an energy source. The introduction of boundary conditions is also explained, as along with plasma transport properties and a method of solution. The paper presents selected results of pressure and velocity fields in the chamber of the plasma generator.

Hlbo?an, Peter; Varchola, Michal; Knížat, Branislav; Mlkvik, Marek; Olšiak, Róbert

2012-12-01

232

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

SciTech Connect

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.

Gessel, Bram van; Bruggeman, Peter [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)] [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Brandenburg, Ronny [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands) [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, D-17489 Greifswald (Germany)

2013-08-05

233

Probe diagnostics of argon-oxygen-tetramethyltin capacitively coupled plasmas for the deposition of tin oxide thin films  

SciTech Connect

Langmuir probe measurements in nondepositing and depositing rf capacitively coupled (CCP) plasmas are briefly reviewed and compared to the results obtained in our rf system used for the deposition of tin oxide (SnO{sub 2}) thin films from argon-oxygen-tetamethyltin [Sn(CH{sub 3}){sub 4}] plasmas. Typically in our experimental conditions for tin oxide deposition, values of kT{sub eff}= 1.2-1.5 eV and n{sub e}=3-5x10{sup 9} cm{sup -3} were measured. These values are consistent with those generally reported in other depositing discharges. The shape of the electron energy probability function (EEPF), obtained from the Druyvesteyn procedure, was discussed too. As a consequence of the two electron heating mechanisms in capacitively coupled discharges, that is, ohmic and stochastic heating, the electrons have a bi-Maxwellian EEPF at low pressure (in the range of 10-100 mTorr). Moreover, a deep 'hole' appears in the EEPF at the energy which could correspond to the resonant peak of the vibrational excitation cross section of some molecules which can be present in the discharge, such as N{sub 2}, CH{sub 4}, or CO.

Pulpytel, J.; Morscheidt, W.; Arefi-Khonsari, F. [Laboratoire de Genie des procedes Plasmas, Ecole Nationale Superieure de Chimie Paris, Universite Pierre et Marie Curie, Paris 6 (France)

2007-04-01

234

Numerical simulation study on fluid dynamics of plasma window using argon  

SciTech Connect

In this paper, a numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the arc and flow field of plasma window, which is used as a windowless vacuum sealing device. The gas inlet, arc creation-developing and plasma expansion segments are all incorporated together in the integral model. An axis-symmetry cathode structure (hollow cathode) is used in the model. Current distribution of the arc is presented and discussed. The temperature, velocity, and pressure field are presented to show the physical mechanisms for the high pressure gap within the plasma window. Flow acceleration and viscosity effect are concluded as the main reasons for the pressure drop. The result for the pressure distribution in the cylindrical tube section has a good agreement with the analytical model. The validation for the sealing ability of plasma window is verified.

Huang, S.; Zhu, K.; Shi, B. L.; Lu, Y. R. [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)] [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Hershcovitch, A. [Brookhaven National Laboratory, New York 11973-5000 (United States)] [Brookhaven National Laboratory, New York 11973-5000 (United States); Yang, L.; Zhang, X. Y.; Wei, G. D. [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China)] [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China)

2013-07-15

235

Argon plasma treatment on Cu surface for Cu bonding in 3D integration and their characteristics  

NASA Astrophysics Data System (ADS)

3D integration enhances RC delay mitigation, improves inter-die bandwidth, and has routing advantages for the next generation integrated circuit technology. To realize the advantages of 3D integration, metallic bonding between different dies or wafers is necessary. So, Cu-to-Cu metallic bonding is, without doubt, a key process needed for 3D integration. In this study, Ar plasma treatment on the Cu surface for Cu thermo-compression bonding temperature less than 400 °C was investigated. Ar plasma treatment on the Cu thin film was performed using a conventional DC sputtering technique. The effect of Cu surface modified by Ar plasma was studied for Cu-to-Cu bonding. Also, the influence of Ar plasma treatment on the Cu surface was evaluated structurally and electrically.

Park, Manseok; Baek, Soojung; Kim, Sungdong; Kim, Sarah Eunkyung

2015-01-01

236

Two-dimensional spatially resolved excitation and rotational temperatures as well as electron number density measurements in capacitively coupled microwave plasmas using argon, nitrogen and air as working gases by spectroscopic methods  

Microsoft Academic Search

Two-dimensional spatially resolved mappings of excitation temperatures, rotational temperatures and electron number densities have been made for capacitively coupled microwave plasmas using argon, nitrogen and air as working gases. The influence of additions of hydrogen to the working gases on the temperature and electron number density profiles in the case of the argon- and nitrogen-CMP is described and found to

N. H. Bings; M. Olschewski; J. A. C. Broekaert

1997-01-01

237

Equations of state, transport properties, and compositions of argon plasma: Combination of self-consistent fluid variation theory and linear response theory  

NASA Astrophysics Data System (ADS)

A consistent theoretical model that can be applied in a wide range of densities and temperatures is necessary for understanding the variation of a material's properties during compression and heating. Taking argon as an example, we show that the combination of self-consistent fluid variational theory and linear response theory is a promising route for studying warm dense matter. Following this route, the compositions, equations of state, and transport properties of argon plasma are calculated in a wide range of densities (0.001 -20 g /c m3) and temperatures (5 -100 kK ) . The obtained equations of state and electrical conductivities are found in good agreement with available experimental data. The plasma phase transition of argon is observed at temperatures below 30 kK and density about 2 -6 g /c m3 . The minimum density for the metallization of argon is found to be about 5.8 g /c m3 , occurring at 30 -40 kK . The effects of many-particle correlations and dynamic screening on the electrical conductivity are also discussed through the effective potentials.

Quan, W. L.; Chen, Q. F.; Fu, Z. J.; Sun, X. W.; Zheng, J.; Gu, Y. J.

2015-02-01

238

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

239

Attenuation of wall disturbances in an electron cyclotron resonance oxygen–argon plasma using real time control  

SciTech Connect

Present practice in plasma-assisted semiconductor manufacturing specifies recipes in terms of inputs such as gas flow rates, power and pressure. However, ostensibly identical chambers running identical recipes may produce very different results. Extensive chamber matching, i.e., initial iterative, empirical tuning of the process recipe, which entails time-consuming, ex situ statistical analysis of process metrics such as etch depth, uniformity, anisotropy and selectivity, is required to ensure acceptable results. Once matched, chambers are run open loop and are thus sensitive to disturbances such as actuator drift, wall seasoning and substrate loading, which may impact negatively on process reproducibility. An alternative approach, which may obviate the need for chamber matching and reduce the sensitivity of process metrics to exogenous disturbances, would be to specify a recipe in terms of quantities such as active species densities, and to regulate these in real time by adjusting the inputs with a suitable control algorithm. In this work, real time control of an electron cyclotron resonance O{sub 2}/Ar plasma used for photoresist ashing has been implemented. The design of elementary, model-based algorithms for the control of the argon 750 and oxygen 844 line intensities measured by optical emission spectroscopy is described. Fluorination of the chamber walls by means of an SF{sub 6} plasma prior to ashing inhibits wall recombination of oxygen radicals resulting in an approximately 20% increase in ash rate in the open loop case. However, closed loop control almost completely attenuates the effect of fluorination, thus demonstrating the efficacy of the control algorithms in ensuring a reproducible ash rate in the face of a wall disturbance.

Keville, Bernard, E-mail: bernard.keville@dcu.ie; Gaman, Cezar; Turner, Miles M. [National Centre for Plasma Science and Technology (NCPST), Research and Engineering Building, Dublin City University, Glasnevin, Dublin 9, Ireland and School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Zhang, Yang; Daniels, Stephen [National Centre for Plasma Science and Technology (NCPST), Research and Engineering Building, Dublin City University, Glasnevin, Dublin 9, Ireland and School of Electronic Engineering, Dublin City University, Glasnevin, Dublin 9 (Ireland); Holohan, Anthony M. [School of Electronic Engineering, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2014-07-01

240

Shock-wave propagation in the plasma of a transverse glow discharge in argon  

SciTech Connect

Shock waves traveling perpendicularly to a glow discharge in an Ar plasma and Ar with no plasma were observed experimentally to examine the dissipation of shock wave energy. A piezoelectric gage attached to a quartz rod furnished the pressure pulse data by which the shock velocities could be monitored at two points in the ambient medium. The shock wave propagated almost three times as fast in the plasma. No connection was found between the speed-up of a shock and decreases in the shock wave amplitude. A correlation was found between the radial change in the shock velocity and the radial electron temperature profile. It is concluded that ion acoustic waves forming ahead of the shock induce an acceleration of the neutral particles and thereby an increase in the velocity of the shock wave. 7 references.

Basargin, I.V.; Mishin, G.I.

1985-02-01

241

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

242

Optical emission measurements of electron energy distributions in low-pressure argon inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

Optical modeling of emissions from low-temperature plasmas provides a non-invasive technique to measure the electron energy distribution function (EEDF) of the plasma. While many models assume the EEDF has a Maxwell-Boltzmann distribution, the EEDFs of numerous plasma systems deviate significantly from the Maxwellian form. In this paper, we present an optical emission model for the Ar(3p54p ? 3p54s) emission array which is capable of capturing details of non-Maxwellian distributions. Our model combines previously measured electron-impact excitation cross sections with Ar(3p54s) number density measurements and emission spectra. The model also includes corrections for radiation trapping of the Ar(3p54p ? 3p54s) emission lines. Results obtained with this optical technique are compared with corresponding Langmuir probe measurements of the EEDF for Ar and Ar/N2 inductively coupled plasma systems operating under a wide variety of source conditions (1-25 mTorr, 20-1000 W, %N2 admixture). Both the optical emission method and probe measurements indicate the EEDF shapes are Maxwellian for low electron energies, but with depleted high energy tails.

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

2010-12-01

243

The effect of helium impurity addition on current sheath speed in argon-operated plasma focus using a tridimensional magnetic probe  

NASA Astrophysics Data System (ADS)

Using the tridimensional magnetic probe, the current sheath velocity at 0.25 Torr is studied in Sahand, a Filippov-type plasma focus facility. The current sheath velocity in argon-filled plasma focus with different percentages of helium impurity at different operating voltages was studied. The highest average current sheath velocity of 12.26 +/- 1.51 cm ?s-1 at the top of the anode in the axial phase was achieved at 17 kV. Minimum average current sheath velocity is 5.24 +/- 1.18 cm ?s-1 at 12 kV with 80% argon + 20% helium as a working gas. The full width at half-maximum of peaks of the magnetic probe was found to be inversely related to the current sheath velocity, i.e. smaller at higher voltages for different impurity and decreased with increasing of impurity.

Panahi, N.; Mohammadi, M. A.; Hedyeh, S.; Rawat, R. S.; Rawat

2013-10-01

244

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

NASA Astrophysics Data System (ADS)

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 3P2, 3P0 (metastable atoms) and 3P1 (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.

Muñoz, J.; Margot, J.; Calzada, M. D.

2012-01-01

245

Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures  

SciTech Connect

Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1?atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1?atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures.

Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady, E-mail: gennady@purdue.edu; Hassanein, Ahmed [Center for Materials Under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-04-15

246

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. PMID:22670128

Görlinger, Klaus; Fries, Dietmar; Dirkmann, Daniel; Weber, Christian F.; Hanke, Alexander A.; Schöchl, Herbert

2012-01-01

247

Silicon nitride etching performance of CH2F2 plasma diluted with argon or krypton  

NASA Astrophysics Data System (ADS)

Etching rates of silicon nitrides (SiN), SiO2, and poly-Si films for CH2F2 plasmas diluted with rare gases are presented by comparing the effects of flow rates of CH2F2 and dilution gases (Ar and Kr). The SiO2 etching rate was considered to be controlled by ion fluxes of the incident CHF2+ and CH2F+ under the conditions for the selective etching of SiO2 and SiN over poly-Si. Interestingly, the SiN etching rate was considerably affected by the dilution gas used. The SiN surface reaction was promoted by F-rich chemistry in the Ar-diluted CH2F2 plasma with a relatively high density of F atoms.

Kondo, Yusuke; Ishikawa, Kenji; Hayashi, Toshio; Miyawaki, Yudai; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

2015-04-01

248

Diamondoid synthesis in atmospheric pressure adamantane-argon-methane-hydrogen mixtures using a continuous flow plasma microreactor  

NASA Astrophysics Data System (ADS)

Due to their small size, low-power consumption and potential for integration with other devices, microplasmas have been used increasingly for the synthesis of nanomaterials. Here, we have investigated the possibility of using dielectric barrier discharges generated in continuous flow glass microreactors for the synthesis of diamondoids, at temperatures of 300 and 320 K, and applied voltages of 3.2-4.3 kVp-p, at a frequency of 10 kHz. The microplasmas were generated in gas mixtures containing argon, methane, hydrogen and adamantane, which was used as a precursor and seed. The plasmas were monitored by optical emission spectroscopy measurements and the synthesized products were characterized by gas chromatography—mass spectrometry (GC-MS). Depending on the gas composition, the optical emission spectra contained CH and C2 bands of varying intensities. The GC-MS measurements revealed that diamantane can be synthesized by microplasmas generated at atmospheric pressure, and that the yields highly depend on the gas composition and the presence of carbon sources.

Stauss, Sven; Ishii, Chikako; Pai, David Z.; Urabe, Keiichiro; Terashima, Kazuo

2014-06-01

249

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

250

Angular distribution of energetic argon ions emitted by a 90 kJ Filippov-type plasma focus  

NASA Astrophysics Data System (ADS)

Characteristics of the energetic argon ions emitted by a 90 kJ Filippov-type plasma focus are studied by employing an array of Faraday cups. The Faraday cups are designed to minimize the secondary electron emission effects on their response. Angular distribution of the ions is measured, and the results indicate a highly anisotropic emission with a dip at the device axis and a local maximum at the angle of 7° with respect to the axis. It has been argued that this kind of anisotropic emission may be related to the surfatron acceleration mechanism and shown that this behavior is independent of the working gas pressure. It has been also demonstrated that this mechanism is responsible for the generation of MeV ions. Measuring the total ion number at different working gas pressures gives an optimum pressure of 0.3 Torr. In addition, the energy spectrum of ions is measured by taking into account of the ambient gas effects on the energy and charge of the ions. The current neutralization effect of electrons trapped in the ion beam as well as the effect of conducting boundaries surrounding the beam, on the detected signals are investigated.

Pestehe, S. J.; Mohammadnejad, M.

2015-02-01

251

Modelling on dynamics properties of a stationary argon cascaded arc plasma flows  

SciTech Connect

The gas dynamics properties of a stationary arc plasma flows are studied through the numerical simulations. A two dimensional axis-symmetric turbulent magneto-hydrodynamic plasma model is developed with the commercial code ANSYS FLUENT. The reliable ?-? model is used to account for turbulence. In this paper, the plasma is assumed to be a fluid following Navier–Stokes equations, respecting local thermodynamic equilibrium, and described by only one temperature. Distributions of the pressure, velocity, temperature, density, and electric potential inside of thus cascaded arc are obtained for an arc current density of 10{sup 6}?A/m{sup 2}. The pressure inside the arc varies from 10{sup 5}?Pa to 100?Pa. The temperature at the arc axis can reach as high as 13?600?K. The electric potential drops uniformly along the axis with a magnitude of 160?V. In addition, distributions of the sonic velocity and Mach number are shown to describe supersonic behavior of thus cascaded arc, which have a good agreement with the analytical formula.

Wei, G. D.; Qi, X.; Yang, L., E-mail: lyang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2014-03-15

252

Modelling on dynamics properties of a stationary argon cascaded arc plasma flows  

NASA Astrophysics Data System (ADS)

The gas dynamics properties of a stationary arc plasma flows are studied through the numerical simulations. A two dimensional axis-symmetric turbulent magneto-hydrodynamic plasma model is developed with the commercial code ANSYS FLUENT. The reliable ?-? model is used to account for turbulence. In this paper, the plasma is assumed to be a fluid following Navier-Stokes equations, respecting local thermodynamic equilibrium, and described by only one temperature. Distributions of the pressure, velocity, temperature, density, and electric potential inside of thus cascaded arc are obtained for an arc current density of 106 A/m2. The pressure inside the arc varies from 105 Pa to 100 Pa. The temperature at the arc axis can reach as high as 13 600 K. The electric potential drops uniformly along the axis with a magnitude of 160 V. In addition, distributions of the sonic velocity and Mach number are shown to describe supersonic behavior of thus cascaded arc, which have a good agreement with the analytical formula.

Wei, G. D.; Qi, X.; Yang, L.

2014-03-01

253

Expansion Dynamics of Ultrafast Laser Produced Plasmas in the Presence of Ambient Argon  

SciTech Connect

In this paper, we report the emission features of fs laser ablated brass plasma plumes at various Ar background pressure levels ranging from vacuum to atmospheric conditions. Spectrally integrated 2D-imaging of plasma self-emission showed several interesting features at various pressure levels which consists of plume morphological changes, increase in persistence, confinement, and internal structures. Spatially resolved wavelength dispersed images of the plume were recorded for characterizing the spectral features at various pressure levels and also used for obtaining spatial distribution of Cu I and Zn I species in the plume, signal to noise ratios and fundamental parameters of the plasma; viz. temperature and density. The spatial evolution of excitation temperature and density showed significant changes at various ambient pressure levels and these results were correlated to morphological changes seen in the plume images. Optimum signal to background ratios for emission lines were observed in the moderate pressure range (~ 1-10 Torr). Optical time-of-flight profiles were used to study time evolution of various species in the plume and noticed oscillations at intermediate pressure levels. Possible mechanisms for observed changes in plume shape, optical emission intensity, and dual peak structures in time-of-flight profiles were discussed.

Diwakar, P. K.; Harilal, Sivanandan S.; Hassanein, A.; Phillips, Mark C.

2014-10-07

254

Systems Biology of Coagulation  

PubMed Central

Accurate computer simulation of blood function can inform drug target selection, patient-specific dosing, clinical trial design, biomedical device design, as well as the scoring of patient-specific disease risk and severity. These large-scale simulations rely on hundreds of independently measured physical parameters and kinetic rate constants. However, the models can be validated against large scale, patient-specific laboratory measurements. By validation with high dimensional data, modelling becomes a powerful tool to predict clinically complex scenarios. Currently, it is possible to accurately predict the clotting rate of plasma or blood in a tube as it is activated with a dose of tissue factor, even as numerous coagulation factors are altered by exogenous attenuation or potentiation. Similarly, the dynamics of platelet activation, as indicated by calcium mobilisation or inside-out signalling, can now be numerically simulated with accuracy in cases where platelets are exposed to combinations of agonists. Multiscale models have emerged to combine platelet function and coagulation kinetics into complete physics-based descriptions of thrombosis under flow. Blood flow controls platelet fluxes, delivery and removal of coagulation factors, adhesive bonding, and von Willebrand factor conformation. The field of Blood Systems Biology has now reached a stage that anticipates the inclusion of contact, complement, and fibrinolytic pathways along with models of neutrophil and endothelial activation. Along with “-omics” data sets, such advanced models seek to predict the multifactorial range of healthy responses and diverse bleeding and clotting scenarios, ultimately to understand and improve patient outcomes. PMID:23809126

Diamond, Scott L.

2013-01-01

255

Argon/UF6 plasma experiments: UF6 regeneration and product analysis  

NASA Technical Reports Server (NTRS)

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 systems. Overall objectives were to continue to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure, gaseous UF6; and to continue development of complementary diagnostic instrumentation and measurement techniques to characterize the effluent exhaust gases and residue deposited on the test chamber and exhaust system components. Specific objectives include: a development of a batch-type UF6 regeneration system employing pure high-temperature fluorine; development of a ruggedized time-of-flight mass spectrometer and associated data acquisition system capable of making on-line concentration measurements of the volatile effluent exhaust gas species in a high RF environment and corrosive environment of UF6 and related halide compounds.

Roman, W. C.

1980-01-01

256

Friction and wear properties of smooth diamond films grown in fullerene-argon plasmas  

SciTech Connect

In this study, we describe the growth mechanism and the ultralow friction and wear properties of smooth (20-50 nm rms) diamond films grown in a microwave plasma consisting of Ar and fullerene (the carbon source). The sliding friction coefficients of these films against Si{sub 3}N{sub 4} balls are 0.04 and 0.1 in dry N{sub 2} and air, which are comparable to that of natural diamond sliding against the same pin material, but is lower by factors of 5 to 10 than that afforded by rough diamond films grown in conventional H{sub 2}-CH{sub 4} plasmas. Furthermore, the smooth diamond films produced in this work afforded wear rates to Si{sub 3}N{sub 4} balls that were two to three orders of magnitude lower than those of H{sub 2}-CH{sub 4} grown films. Mechanistically, the ultralow friction and wear properties of the fullerene-derived diamond films correlate well with their initially smooth surface finish and their ability to polish even further during sliding. The wear tracks reach an ultrasmooth (3-6 nm rms) surface finish that results in very little abrasion and ploughing. The nanocrystalline microstructure and exceptionally pure sp{sup 3} bonding in these smooth diamond films were verified by numerous surface and structure analytical methods, including x-ray diffraction, high-resolution AF-S, EELS, NEXAFS, SEM, and TEM. An AFM instrument was used to characterize the topography of the films and rubbing surfaces.

Erdemir, A.; Fenske, G.R.; Bindal, C.; Zuiker, C.; Krauss, A.R.; Gruen, D.M.

1995-08-01

257

Successful Treatment of Discoid Lupus erythematosus with Argon Laser  

Microsoft Academic Search

Vascular lesions with telangiectasias on visible areas, such as the face, are common in discoid lupus erythematosus (DLE); however, an efficient management of these skin lesions can sometimes be difficult. Since argon laser light is able to specifically coagulate vascular structures, it has been used in the treatment of various vascular skin malformations. Therefore, we addressed the issue whether argon

Annegret Kuhn; Petra Maria Becker-Wegerich; Thomas Ruzicka; Percy Lehmann

2000-01-01

258

On the difference between breakdown and quench voltages of argon plasma and its relation to $4p-4s$ atomic state transitions  

E-print Network

Using a relaxation oscillator circuit, breakdown ($V_{\\mathrm{BD}}$) and quench ($V_{\\mathrm{Q}}$) voltages of a DC discharge microplasma between two needle probes are measured. High resolution modified Paschen curves are obtained for argon microplasmas including a quench voltage curve representing the voltage at which the plasma turns off. It is shown that, for a point to point microgap (e.g. the microgap between two needle probes) which describes many realistic microdevices, neither Paschen's law applies nor field emission is noticeable. Although normally $V_{\\mathrm{BD}}>V_{\\mathrm{Q}}$, it is observed that depending on environmental parameters of argon, such as pressure and the driving circuitry, plasma can exist in a different state with equal $V_{\\mathrm{BD}}$ and $V_{\\mathrm{Q}}$. Using emission line spectroscopy, it is shown that $V_{\\mathrm{BD}}$ and $V_{\\mathrm{Q}}$ are equal if the atomic excitation by the electric field dipole moment dominantly leads to one of the argon's metastable states ($4P_{5...

Forati, Ebrahim; Sievenpiper, Dan

2014-01-01

259

PF-04886847 (an inhibitor of plasma kallikrein) attenuates inflammatory mediators and activation of blood coagulation in rat model of lipopolysaccharide (LPS)-induced sepsis.  

PubMed

The plasma kallikrein-mediated proteolysis regulates both thrombosis and inflammation. Previous study has shown that PF-04886847 is a potent and competitive inhibitor of kallikrein, suggesting that it might be useful for the treatment of kallikrein-kinin mediated inflammatory and thrombotic disorders. In the rat model of lipopolysaccharide (LPS) -induced sepsis used in this study, pretreatment of rats with PF-04886847 (1 mg/kg) prior to LPS (10 mg/kg) prevented endotoxin-induced increase in granulocyte count in the systemic circulation. PF-04886847 significantly reduced the elevated plasma 6-keto PGF1? levels in LPS treated rats, suggesting that PF-04886847 could be useful in preventing hypotensive shock during sepsis. PF-04886847 did not inhibit LPS-induced increase in plasma TNF-? level. Pretreatment of rats with PF-04886847 prior to LPS did not attenuate endotoxin-induced decrease in platelet count and plasma fibrinogen levels as well as increase in plasma D-dimer levels. PF-04886847 did not protect the animals against LPS-mediated acute hepatic and renal injury and disseminated intravascular coagulation (DIC). Since prekallikrein (the zymogen form of plasma kallikrein) deficient patients have prolonged activated partial thromboplastin time (aPTT) without having any bleeding disorder, the anti-thrombotic property and mechanism of action of PF-04886847 was assessed. In a rabbit balloon injury model designed to mimic clinical conditions of acute thrombotic events, PF-04886847 reduced thrombus mass dose-dependently. PF-04886847 (1 mg/kg) prolonged both aPTT and prothrombin time (PT) in a dose-dependent manner. Although the findings of this study indicate that PF-04886847 possesses limited anti-thrombotic and anti-inflammatory effects, PF-04886847 may have therapeutic potential in other kallikrein-kinin mediated diseases. PMID:22352684

Kolte, D; Bryant, J W; Gibson, G W; Wang, J; Shariat-Madar, Z

2012-06-01

260

A collisional and radiative model of argon plasma for application to ionization phenomena behind a shock wave  

Microsoft Academic Search

A formulation has been performed for the description of excited-level population-densities and gasdynamic properties in nonequilibrium ionizing argon gas. The energy-level structure of an argon atom is assumed to be composed of six actual levels and higher hydrogenic levels. The ionization and excitation due to atom-atom and atom-electron inelastic collisions, as well as radiative transition including the self-absorption effect, are

Y. Takano; T. Akamatsu

1982-01-01

261

Laser Optogalvanic Spectroscopy pf Neon and Argon in a Discharge Plasma and its Significance for Microgravity Combustion  

NASA Technical Reports Server (NTRS)

A detailed study of combustion mechanisms in flames, employing laser-based diagnostics, has provided good knowledge and understanding of the physical phenomena, and led to better characterization of the dynamical and chemical combustion processes, both under low-gravity (in space) and normal gravity (in ground based facilities, e.g. drop towers). Laser induced fluorescence (LIF), laser-induced incandescence (LII) and LIF thermometry have been widely used to perform nonintrusive measurements and to better understand combustion phenomena. Laser optogalvanic (LOG) spectroscopy has well-established applications in ion mobility measurements, atomic and molecular spectroscopy, ionization rates, recombination rates, velocity measurements and as a combustion probe for trace element detection. Absorption spectra of atomic and molecular species in flames can be obtained via LOG spectroscopy by measuring the voltage and current changes induced by laser irradiation. There are different kinds of processes that contribute to a discharge current, namely: (1) electron impact ionization, (2) collisions among the excited atoms of the discharge species and (3) Penning ionization. In general, at higher discharge currents, the mechanism of electron impact ionization dominates over Penning ionization, whereby the latter is hardly noticeable. In a plasma, whenever the wavelength of a laser coincides with the absorption of an atomic or molecular species, the rate of ionization of the species momentarily increases or decreases due to laser-assisted acceleration of collisional ionization. Such a rate of change in the ionization is monitored as a variation in the transient current by inserting a high voltage electrode into the plasma. Optogalvanic spectroscopy in discharges has been useful for characterizing laser line-widths and for providing convenient calibration lines for tunable dye lasers in the ultraviolet, visible and infrared wavelength regions. Different kinds of quantitative information, such as the electron collisional ionization rate, can be extracted from the complex processes occurring within the discharge. In the optogalvanic effect (OGE), there is no problem of overlap from background emissions, and hence even weak signals can be detected with a high signal-to-noise ratio, which makes the optogalvanic effect sensitive enough to resolve vibrational changes in molecular bonds and differences in energy levels brought about by different electron spins. For calibration purposes, neon and argon gaseous discharges have been employed most extensively, because these gases are commonly used as buffer gases within hollow-cathode lamps and provide an acceptable density of calibration lines. In the present work, our main aim has been to understand the dominant physical processes responsible for the production of the OGE signal, based on the extensive time resolved optogalvanic waveforms recorded, and also to extract quantitative information on the rates of excited state collisional processes.

Misra, Prabhakar; Haridass, C.; Major, H.

1999-01-01

262

Hydroxyurea Increases Plasma Concentrations of Microparticles and Reduces Coagulation Activation and Fibrinolysis in Patients with Sickle Cell Anemia.  

PubMed

Microparticles (MPs) are present in healthy subjects and their concentration increases in patients at high risk of thrombosis. We evaluated 10 patients with sickle cell anemia (SCA) treated with hydroxyurea (HU) and 13 SCA patients without this treatment. MP concentrations were determined by flow cytometry. Coagulation was evaluated using the thrombin-antithrombin complex (TAT) and D-dimers. Total MP concentrations were increased in the HU-treated group (265 × 10(6)/ml vs. 67.45 × 10(6)/ml; p = 0.0026), as well as MPs derived from RBC (67.83 × 10(6)/ml vs. 26.31 × 10(6)/ml; p = 0.05), monocytes (51.31 × 10(6)/ml vs. 9.03 × 10(6)/ml; p = 0.0084), monocytes with tissue factor (TF) expression (2.27 × 10(6)/ml vs. 0.27 × 10(6)/ml; p = 0.0058), endothelium (49.42 × 10(6)/ml vs. 7.23 × 10(6)/ml; p = 0.007) and endothelium with TF (1.42 × 10(6)/ml vs. 0.26 × 10(6)/ml; p = 0.0043). Furthermore, the concentrations of TAT (7.56 vs. 10.98 µg/l; p = 0.014) and D-dimers (0.65 vs. 1.29 µg/ml; p = 0.007) were reduced with HU. The MP elevation may suggest a direct cytotoxic effect of HU. Another explanation is a cell surface increase secondary to a megaloblastic process, resulting in increased vesicle release. In our opinion, the known benefits of HU on SCA patients, along with the reduction in coagulation activation, surpass its potential detrimental effect on MPs. Future studies should elucidate the role of MPs and demonstrate their significance in different contexts. © 2014 S. Karger AG, Basel. PMID:25472687

Brunetta, Denise Menezes; De Santis, Gil Cunha; Silva-Pinto, Ana Cristina; Oliveira de Oliveira, Luciana Correa; Covas, Dimas Tadeu

2014-12-01

263

Argon Plasma Surgery for Treatment of Inferior Turbinate Hypertrophy: A Long-Term Follow-Up in 157 Patients  

Microsoft Academic Search

Chronic nasal obstruction is a common disorder, mostly caused by hypertrophic inferior turbinates. In cases of nonresponse to conservative medical management, the surgical reduction of the inferior turbinates is often required. Surgical techniques for the reduction of hyperplastic nasal turbinates include monopolar or bipolar coagulation, partial or total reduction of the turbinates with a conchotome or scissors and laser surgery

E. Ferri; E. Armato; S. Cavaleri; P. Capuzzo; F. Ianniello

2003-01-01

264

First principles transport coefficients and reaction rates of Ar_2^+ ions in argon for cold plasma jet modeling  

NASA Astrophysics Data System (ADS)

Momentum-transfer collision cross-sections and integral collision cross-sections for the collision-induced dissociation are calculated for collisions of ionized argon dimers with argon atoms using a nonadiabatic semiclassical method with the electronic Hamiltonian calculated on the fly via a diatomics-in-molecules semiempirical model as well as inverse-method modeling based on simple isotropic rigid-core potential. The collision cross-sections are then used in an optimized Monte Carlo code for evaluations of the Ar_2^+ mobility in argon gas, longitudinal diffusion coefficient, and collision-induced dissociation rates. A thorough comparison of various theoretical calculations as well as with available experimental data on the Ar_2^+ mobility and collision cross-sections is performed. Good agreement is found between both theoretical approaches and the experiment. Analysis of the role of inelastic processes in Ar_2^+/Ar collisions is also provided.

Chicheportiche, Alexandre; StachoÅ, Martin; Benhenni, Malika; Gadéa, Florent Xavier; Kalus, René; Yousfi, Mohammed

2014-10-01

265

Usefulness of standard plasma coagulation tests in the management of perioperative coagulopathic bleeding: is there any evidence?  

PubMed

Standard laboratory coagulation tests (SLTs) such as prothrombin time/international normalized ratio or partial thromboplastin time are frequently used to assess coagulopathy and to guide haemostatic interventions. However, this has been challenged by numerous reports, including the current European guidelines for perioperative bleeding management, which question the utility and reliability of SLTs in this setting. Furthermore, the arbitrary definition of coagulopathy (i.e. SLTs are prolonged by more than 1.5-fold) has been questioned. The present study aims to review the evidence for the usefulness of SLTs to assess coagulopathy and to guide bleeding management in the perioperative and massive bleeding setting. Medline was searched for investigations using results of SLTs as a means to determine coagulopathy or to guide bleeding management, and the outcomes (i.e. blood loss, transfusion requirements, mortality) were reported. A total of 11 guidelines for management of massive bleeding or perioperative bleeding and 64 studies investigating the usefulness of SLTs in this setting were identified and were included for final data synthesis. Referenced evidence for the usefulness of SLTs was found in only three prospective trials, investigating a total of 108 patients (whereby microvascular bleeding was a rare finding). Furthermore, no data from randomized controlled trials support the use of SLTs. In contrast, numerous investigations have challenged the reliability of SLTs to assess coagulopathy or guide bleeding management. There is actually no sound evidence from well-designed studies that confirm the usefulness of SLTs for diagnosis of coagulopathy or to guide haemostatic therapy. PMID:25204698

Haas, T; Fries, D; Tanaka, K A; Asmis, L; Curry, N S; Schöchl, H

2015-02-01

266

Ultraviolet versus infrared: Effects of ablation laser wavelength on the expansion of laser-induced plasma into one-atmosphere argon gas  

SciTech Connect

Laser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV: 355 nm) or infrared (IR: 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy.

Ma Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu Jin [Universite de Lyon, F-69622, Lyon, France, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Lei Wenqi; Bai Xueshi; Zheng Lijuan; Zeng Heping [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai (China)

2012-03-01

267

Convoluted effect of laser fluence and pulse duration on the property of a nanosecond laser-induced plasma into an argon ambient gas at the atmospheric pressure  

SciTech Connect

We studied the behavior of the plasma induced by a nanosecond infrared (1064 nm) laser pulse on a metallic target (Al) during its propagation into argon ambient gas at the atmospheric pressure and especially over the delay interval ranging from several hundred nanoseconds to several microseconds. In such interval, the plasma is particularly interesting as a spectroscopic emission source for laser-induced plasma spectroscopy (LIBS). We show a convoluted effect between laser fluence and pulse duration on the structure and the emission property of the plasma. With a relatively high fluence of about 160 J/cm{sup 2} where a strong plasma shielding effect is observed, a short pulse of about 4 ns duration is shown to be significantly more efficient to excite the optical emission from the ablation vapor than a long pulse of about 25 ns duration. While with a lower fluence of about 65 J/cm{sup 2}, a significantly more efficient excitation is observed with the long pulse. We interpret our observations by considering the post-ablation interaction between the generated plume and the tailing part of the laser pulse. We demonstrate that the ionization of the layer of ambient gas surrounding the ablation vapor plays an important role in plasma shielding. Such ionization is the consequence of laser-supported absorption wave and directly dependent on the laser fluence and the pulse duration. Further observations of the structure of the generated plume in its early stage of expansion support our explanations.

Bai Xueshi; Ma Qianli; Motto-Ros, Vincent; Yu Jin [Universite de Lyon, F-69622, Lyon, France, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Sabourdy, David; Nguyen, Luc; Jalocha, Alain [CILAS Laser Company, Photonics Department, 45000 Orleans (France)

2013-01-07

268

An investigation of Ar metastable state density in low pressure dual-frequency capacitively coupled argon and argon-diluted plasmas  

NASA Astrophysics Data System (ADS)

An tunable diode laser absorption spectroscopy has been used to determine the Ar*(3P2) and Ar*(3P0) metastable atoms densities in dual-frequency capacitively coupled plasmas. The effects of different control parameters, such as high-frequency power, gas pressure and content of Ar, on the densities of two metastable atoms and electron density were discussed in single-frequency and dual-frequency Ar discharges, respectively. Particularly, the effects of the pressure on the axial profile of the electron and Ar metastable state densities were also discussed. Furthermore, a simple rate model was employed and its results were compared with experiments to analyze the main production and loss processes of Ar metastable states. It is found that Ar metastable state is mainly produced by electron impact excitation from the ground state, and decayed by diffusion and collision quenching with electrons and neutral molecules. Besides, the addition of CF4 was found to significantly increase the metastable destruction rate by the CF4 quenching, especially for large CF4 content and high pressure, it becomes the dominant depopulation process.

Liu, Wen-Yao; Xu, Yong; Liu, Yong-Xin; Peng, Fei; Guo, Qian; Li, Xiao-Song; Zhu, Ai-Min; Wang, You-Nian

2015-01-01

269

Safety and efficacy of plasma-derived coagulation factor IX concentrate (AlphaNine® SD) in patients with haemophilia B undergoing surgical intervention: a single institution retrospective analysis.  

PubMed

While coagulation factor replacement is essential in surgical intervention in haemophilia B patients, few studies are available on the safety and efficacy of plasma-derived factor IX (FIX) for haemostasis during surgery. This retrospective study examined outcomes in these patients. A total of 20 patients who underwent 29 surgical procedures at the Hemophilia Treatment Center at Orthopaedic Hospital in Los Angeles, California, were identified and their inpatient charts were reviewed and abstracted. Outcomes included pre- and postoperative FIX dosing, recovery of FIX, blood loss, use of blood products, safety and haemostatic response. Identified patients had mild (10%), moderate (15%) or severe (75%) haemophilia B, and average age at surgery was 48.5 years. All surgical procedures were major (orthopaedic 89.7%; abdominal 10.3%), all were completed under general anaesthesia, and average time in surgery was 3.25 h. Average hospital length of stay was 11.0 days [standard deviation (SD) = 8.5] and all patients were discharged home. All patients were treated with AlphaNine® SD at an average dose of 254.9 IU kg(-1) (SD = 65.4) on the day of surgery and the dose was adjusted over the course of hospital stay. Mean perioperative blood loss was 255.5 mL (SD = 283.1) and blood replacement was required in only two surgeries (6.9%). FIX recovery analysis performed preoperatively related well to FIX levels obtained. Identified patients had little blood loss perioperatively and had no bleeding related complications. Plasma-derived FIX pre- and postoperatively appeared to be a safe and effective treatment in haemophilia B patients undergoing surgery. PMID:20618876

Quon, D V K; Logan, L

2011-01-01

270

Emission spectra of an argon inductively coupled plasma in the vacuum ultraviolet: background spectra from 85 to 200 nm  

NASA Astrophysics Data System (ADS)

The background spectra emitted from an argon ICP discharge have been recorded over the spectral range 85 to 200 nm. These vacuum ultraviolet spectra were acquired by coupling the ICP to a 0.5-m Seya-Namioka vacuum monochromator, through a helium purged side-arm. Background features observed include emission from the resonance lines of ArI, and emission from gas impurities such as oxygen, nitrogen, carbon and hydrogen.

Carr, J. W.; Blades, M. W.

271

Interspecies differences in coagulation profile.  

PubMed

Many animals are used in research on blood coagulation and fibrinolysis, but the relevance of animal models to human health is often questioned because of differences between species. The objective was to find an appropriate animal species, which mimics the coagulation profile in humans most adequately. Species differences in the coagulation profile with and without thrombin stimulation in vitro were assessed in whole blood by Rotation Thromboelastometry (ROTEM). Endogenous thrombin generation was measured in platelet-poor plasma. Measurements were performed in blood from five different species: humans, rats, pigs, sheep and rabbits. In humans and sheep, the clotting time (ROTEM) was in the same range with or without thrombin stimulation and a 100-fold lower dose of thrombin (0.002 IU) was required to cause a shortening in the clotting time as compared to rats, pigs and rabbits (0.2 IU) (p<0.05). Similarly, the endogenous thrombin potential (ETP) was in the same range in humans and sheep. The maximum clot firmness with or without thrombin stimulation was similar in rabbits and humans. The maximum lysis with or without thrombin stimulation was similar in humans and pigs. Significant species differences exist in the coagulation profile with or without thrombin stimulation. Most importantly, sheep had a clotting time most similar to humans and could thus be a suitable species for translational coagulation studies. Moreover, our findings confirm the potential usefulness of pigs as an experimental species to study fibrinolytic pathway and support the usefulness of rabbits as a species for examining platelets. PMID:18766254

Siller-Matula, Jolanta M; Plasenzotti, Roberto; Spiel, Alexander; Quehenberger, Peter; Jilma, Bernd

2008-09-01

272

Application of abnormally high sputtering rate of PbTe(Te) single crystals during inductively coupled argon plasma treatment for fabrication of nanostructures  

NASA Astrophysics Data System (ADS)

This paper reports the investigations of the sputtering process of (111) oriented single crystals of PbTe with excess tellurium (4 at.%) in RF high-density low-pressure inductively coupled argon plasma. An increase of 1.6 times the sputtering rate of lead telluride in comparison with the classical case of single-crystal state with a slight deviation from stoichiometry is shown and the explanation of the results is carried out based on the analysis of the crystal point defects. The active sputtering is used in a new approach to form lead telluride nanostructures on oxidized Si substrates via the vapour–liquid–solid (VLS) redeposition mechanism, and the fabrication of PbTe nanocones, nanocubes and nanowires with various geometrical parameters is demonstrated.

Zimin, S. P.; Gorlachev, E. S.; Amirov, I. I.; Naumov, V. V.; Bagiyeva, G. Z.

2015-03-01

273

Measurement of ion density in an atmospheric pressure argon with pin-to-plate dielectric barrier discharge by resonance of plasma radiation  

NASA Astrophysics Data System (ADS)

The measurements of the ion densities in the atmospheric AC barrier corona argon discharge are carried out by receiving and analyzing the frequencies of the electromagnetic radiation emitted from the plasma. An auxiliary excitation source composed of a pin-to-pin discharge system is introduced to excite the oscillations of the main discharge. To analyze the resonance mechanism, a complemented model based on a one-dimensional description of forced vibrations is given. Calculations indicate that Ar2 + is the dominant ion ( ˜ 89 % in number density). By analyzing resonance frequencies, the ion densities of Ar2 + are in the order of 10 19 ˜ 10 20 m - 3 and increase slowly as the applied voltage increases.

Qi, Bing; Pan, Lizhu; Zhou, Qiujiao; Huang, Jianjun; Liu, Ying

2014-12-01

274

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. PMID:21375741

2011-01-01

275

Departure from Local Thermodynamic Equilibrium in argon plasmas sustained in a Torche à Injection Axiale sur Guide d'Ondes  

NASA Astrophysics Data System (ADS)

Plasma torches are suitable plasma sources for a wide range of applications. The capability of these discharges to produce processes like sample excitation or decomposition of molecules inside them depends on the density of the plasma species and their energies (temperatures). The relation between these parameters determines the specific state of thermodynamic equilibrium in the discharge. Thus, the understanding of plasma possibilities for application purposes is related to the knowledge of the plasma thermodynamic equilibrium degree. In this paper a discussion about the equilibrium state for Ar plasmas generated by using a Torche à Injection Axiale sur Guide d'Ondes, TIAGO device, is presented. Emission spectroscopy techniques were used to measure gas temperature and electron density at the exit of the nozzle torch and along the dart. Boltzmann-plots as well as bp parameters were calculated to characterize the type and degree of departure from partial Local Saha Equilibrium (pLSE). This study indicates that the closer situation to Local Thermodynamic Equilibrium (LTE) of the plasma corresponds to larger Ar flows which highlights the importance of the nitrogen (atmosphere surrounding the plasma) in the kinetics of Ar-TIAGO discharges.

Rincón, R.; Muñoz, J.; Calzada, M. D.

2015-01-01

276

Bipolar coagulation - capable microforceps  

Microsoft Academic Search

Microforceps that can be used with the hyper utility mechatronic assistant system (HUMAN) for bipolar coagulation in minimally invasive neurosurgery were developed. A method of using two sets of those forceps for bipolar coagulation was developed, in which electrical current is passed through the drive wires to the forceps tips to form an electrical circuit. A prototype mechanism that employs

TOSHIKAZU KAWAI; KAZUTOSHI KAN; KAZUHIRO HONGO; KOUJI NISHIZAWA; FUJIO TAJIMA; MASAKATSU G. FUJIE; TAKEYOSHI DOHI; KINTOMO TAKAKURA

2005-01-01

277

The determination of ranges of selected properties of an argon plasma using an electric arc of limited power  

E-print Network

Energy Inputs Range of Plasmas Generated 0 12 15 27 28 Close-up of Arc Chamber and Plasma Jet. . . , 41 Over-all View of Plasma Generator 41 10 The Arc Chamber, Control Console and Instrumentation 42 Exploded View of Nozzle Flange, Nozzle... the manometer to fluctuate rapidly, prohibiting accurate readings. The pressure in the vacuum tank and the pressure of the pitot tube were measured on Meriam, type W, Madel A-203, 30-inch mercury manometers mounted on the control console. The pitot tube...

Farquhar, Bannister Wells

1963-01-01

278

Observation of inactivation of Bacillus sbtilis spores under exposures of oxygen added argon atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

The inactivation of Bacillus subtilis spores by an Ar plasma jet mixed with different amounts of oxygen is reported. 5.8 × 106 B. subtilis spores are sterilized by an Ar/O2 (8.7%) plasma jet after exposure for 2 min. The densities of ozone and oxygen radicals in the Ar/O2 plasma jet increase with oxygen concentration and are estimated by optical spectroscopy diagnostic. The malondialdehyde (MDA) test shows that oxygen radicals participate in bacterial inactivation. Scanning electron microscopy (SEM) reveals the deformation of the spore shape due to etching by oxygen radicals and the dependence of the degree of deformation on the density of oxygen radicals.

Shen, Jie; Cheng, Cheng; Zhao, Ying; Xiao, Dezhi; Lan, Yan; Xie, Hongbing; Cheng, Junli; Meng, Yuedong; Li, Jiangang; Chu, Paul K.

2014-11-01

279

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  

NASA Astrophysics Data System (ADS)

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 of the non-LTE ionization dynamics and radiation transport physics. In this study, we focus on the implementation of the TCRE radiation transport model in the Mach2 2D radiation MHD code. An application of the model is made through a full dynamical simulation of an argon gas puff pinch driven by a circuit model of the Z generator. An analysis of the simulation, in particular, the K- and L-shell radiation yields, as well as the spectral and spatial characteristics of the radiation will be presented. In addition, a comparison of this multidimensional transport method will be made with the existing radiative diffusion model.

Chong, Y. K.; Thornhill Giuliani, J. W., Jr.; Apruzese, J. P.; Terry, R. E.; Davis, J.

2001-10-01

280

Initiation and propagation of coagulation from tissue factor-bearing cell monolayers to plasma: initiator cells do not regulate spatial growth rate  

Microsoft Academic Search

Summary. Exposure of tissue factor (TF)-bearing cells to blood is the initial event in coagulation and intravascular thrombus formation. However, the mechanisms which deter- mine thrombus growth remain poorly understood. To explore whether the procoagulant activity of vessel wall-bound cells regulates thrombus expansion, we studied in vitro spatial clot growth initiated by cultured human cells of different types in contact

M. V. OVANESOV; N. M. ANANYEVA; M. A. PANTELEEV; F. I. ATAULLAKHANOV; E. L. SAENKO

2005-01-01

281

2D collisional-radiative model for non-uniform argon plasmas: with or without ‘escape factor’  

NASA Astrophysics Data System (ADS)

Collisional-radiative models for excited rare-gas atoms in low-temperature plasmas are a widely investigated topic. When these plasmas are optically thick, an ‘escape factor’ is introduced into the models to account for the reabsorption of photons (so-called radiation trapping process). This factor is usually obtained assuming a uniform density profile of the excited species; however, such an assumption is often not satisfied in a bounded plasma. This article reports for the first time a self-consistent collisional-radiative model without using an ad hoc ‘escape factor’ for excited Ar atoms in the 2p states (in Paschen’s notation). Rather, the rate balance equations—i.e. the radiation transfer equations—of the 2p states are numerically solved to yield the actual density profiles. The predictions of this self-consistent model and a model based on the escape factor concept are compared with spatially-resolved emission measurements in a low-pressure inductive Ar plasma. The self-consistent model agrees well with the experiment but the ‘escape factor’ model shows considerable deviations. By the comparative analysis the limitations and shortcomings of the escape factor concept as adopted in a significant number of works are revealed.

Zhu, Xi-Ming; Vaskov Tsankov, Tsanko; Luggenhölscher, Dirk; Czarnetzki, Uwe

2015-03-01

282

Determination of ionic and neutral components of argon-methyl methacrylate radiofrequency discharge plasma by mass spectrometry  

SciTech Connect

Positive ions and neutral species formed in the plasma of a radiofrequency discharge in an argonmethyl methacrylate (MMA) mixture at 5.28 MHz, discharge power 12 - 130 W, pressure 10 - 100 Pa, and 0.5 - 10% MMA content of the gas mixture were investigated by mass spectrometry. Over 30 different ionic species were identified in the plasma under various experimental conditions. The most abundant plasma ions were as follows (the m/e values are given in parentheses): CH{sub 3}{sup +} (15), C{sub 2}H{sub 2}{sup +} (26), C{sub 2}H{sub 3}{sup +} (27), C{sub 2}H{sub 4}{sup +}, CO{sup +} (28), C{sub 2}H{sub 5}{sup +}, C{sub 2}H{sub 5}{sup +}, HCO{sup +} (29), C{sub 3}H{sub 3}{sup +} (39), Ar{sup +} (40), C{sub 3}H{sub 5}{sup +} (41), COOCH{sub 3}{sup +} (101). At the MMA concentrations studied, Ar{sup +} was the principal ionic component of the plasma. Among the neutral plasma components, 28 compounds were identified, including C{sub 1}-C{sub 6} hydrocarbons, H{sub 2},H{sub 2}O, CO, HCOH, CH{sub 3}OH, CO{sub 2}, CH{sub 3}COCH{sub 3}, and C{sub 3}H{sub 7}COH. The experimental data suggest that both electron-impact-induced dissociation and ion-molecule reactions involving Ar{sup +}MMA mixture.

Shcheglov, A.N.; Vasilets, V.N.; Ponomarev, A.N. [Institute of Energy Problems of Chemical Physics, Moscow (Russian Federation)

1995-09-01

283

Bustling argon: biological effect  

PubMed Central

Argon is a noble gas in group 18 of the periodic table. Certificated to exist in air atmosphere merely one century ago, discovery of argon shows interesting stories of researching and exploring. It was assumed to have no chemical activity. However, argon indeed present its biological effect on mammals. Narcotic effect of argon in diving operation and neur-protective function of argon in cerebral injury demonstrate that argon has crucial effect and be concentrated on is necessary. Furthermore, consider to be harmless to human, argon clinical application in therapy would be another option. PMID:24088583

2013-01-01

284

Coagulation and Mental Disorders  

PubMed Central

The neurovascular unit is a key player in brain development, homeostasis, and pathology. Mental stress affects coagulation, while severe mental illnesses, such as recurrent depression and schizophrenia, are associated with an increased thrombotic risk and cardiovascular morbidity. Evidence indicates that the hemostatic system is involved to some extent in the pathogenesis, morbidity, and prognosis of a wide variety of psychiatric disorders. The current review focuses on emerging data linking coagulation and some psychiatric disorders. PMID:25386352

Hoirisch-Clapauch, Silvia; Nardi, Antonio Egidio; Gris, Jean-Christophe; Brenner, Benjamin

2014-01-01

285

Density of atoms in Ar*(3p{sup 5}4s) states and gas temperatures in an argon surfatron plasma measured by tunable laser spectroscopy  

SciTech Connect

This study presents the absolute argon 1 s (in Paschens's notation) densities and the gas temperature, T{sub g}, obtained in a surfatron plasma in the pressure range 0.6510 mbar, for which the pressure broadening can no more be neglected. T{sub g} is in the range of 480-750 K, increasing with pressure and decreasing with the distance from the microwave launcher. Taking into account the line of sight effects of the absorption measurements, a good agreement is found with our previous measurements by Rayleigh scattering of T{sub g} at the tube center. In the studied pressure range, the Ar(4 s) atom densities are in the order of 10{sup 16}-10{sup 18} m{sup -3}, increasing towards the end of the plasma column, decreasing with the pressure. In the low pressure side, a broad minimum is found around 10

Huebner, S.; Carbone, E. A. D.; Mullen, J. J. A. M. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven (Netherlands); Sadeghi, N. [LIPhy, Universite Joseph Fourier and CNRS, UMR 5588, Grenoble F-38041 (France)

2013-04-14

286

Nonlinear Interaction Between the Radiation and Multidimensional Plasma in Large Diameter Structured Argon Gas Puff Z-Pinch Loads  

NASA Astrophysics Data System (ADS)

It has recently been demonstrated that one can efficiently produce K-shell x-ray radiation with z pinches imploded from larger initial diameters, by longer current pulses than previously thought possible, using a ``pusher-stabilizer-radiator'' load formed by a supersonic nozzle injecting outer and inner annular shells and a high-density central jet between the cathode and the anode [1]. We present a detailed numerical investigation of the implosions of such loads. Our simulations were performed with the 2D RMHD Mach2 code incorporating the dynamical domain tabular collisional radiative equilibrium (DDTCRE) radiation transport model [2]. This model provides a realistic description of the self-consistent multidimensional non-local non-LTE ionization dynamics and radiation transport physics in a computationally efficient manner. A numerical simulation analysis of various nozzle load configurations, with/without the central jet and/or shells, is used to further assess and validate the physical model by simulating the experimental spectra, plasma images and radiation emission characteristics. [1] H. Sze et al., PRL 95, 105001(2005). [2] Y. K. Chong et al., ICOPS 2005, Monterey, CA.

Chong, Y. K.; Thornhill, J. W.; Velikovich, A. L.; Apruzese, J. P.; Davis, J.; Qi, N.; Sze, H.; Levine, J. S.; Failor, B. H.

2006-10-01

287

The role of platelets in blood coagulation during thrombus formation in flow  

E-print Network

The role of platelets in blood coagulation during thrombus formation in flow A. Tosenberger1,2 , F of aggregating platelets with biochemical reactions in plasma that participate in blood coagulation (DPD) is used to model plasma flow with platelets while fibrin concentration is described

Paris-Sud XI, Université de

288

The Coagulated Behavior of Latex Particles in a Seed Coagulation  

NASA Astrophysics Data System (ADS)

The coagulated behavior of latex particles in a seed coagulation was investigated. The latex particle formed the higher order coagulated structure, which consists of primary coagulates, and it was found that the temperature and the mixing condition significantly affected the size of cluster. We also proposed the procedure to predict the size of cluster from viscosity data of latex particle slurry by the use of the thixotropy model presented by Usui

Fukui, Masatsugu; Ueda, Takashi; Komoda, Yoshiyuki; Suzuki, Hiroshi; Usui, Hiromoto

2008-07-01

289

Characterization of the behavior of chemically reactive species in a nonequilibrium inductively coupled argon-hydrogen thermal plasma under pulse-modulated operation  

SciTech Connect

The temporal and spatial dependence of species densities in a pulse-modulated inductively coupled plasma (PM-ICP) in an argon-hydrogen mixture was investigated by means of numerical modeling, taking into account time dependence, two temperatures, and chemical nonequilibrium, and also through spectroscopic measurements. Conservation equations for mass, momentum, electron energy, heavy-species energy, each species, and the electromagnetic field were developed and solved self-consistently. The transient behavior of the mass fraction of each species was determined by including chemical kinetics source terms in the species conservation equations. Fourteen chemical reactions involving seven species (e, Ar, Ar{sup +}, H{sub 2}, H{sub 2}{sup +}, H, and H{sup +}) were considered. The transport properties were evaluated based on the local species densities using the first-order approximation of the Chapman-Enskog method. Time-resolved electron density profiles were obtained from measurements of the Stark broadening of the H{sub {beta}} line (486.1 nm), performed using an optical system positioned using a stepper motor. The investigations were conducted for a maximum power level of 11.7 kW with a duty factor of 66.7% and at a pressure of 27 kPa. Reasonable agreement was found between the predicted and measured electron densities. The electron density in the discharge region varied considerably over a pulse cycle, while the hydrogen atom density remained high throughout the cycle, and peaked in a region that has been experimentally demonstrated to have optimal efficiency for hydrogen doping of materials. The main mechanisms responsible for the production of the relevant species in the PM-ICP are discussed.

Ye, Rubin; Ishigaki, Takamasa; Taguchi, Hiroyuki; Ito, Shigeru; Murphy, Anthony B.; Lange, Hubert [Nano Ceramics Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Department of Pure and Applied Chemistry, Tokyo University of Science, Yamazaki, Noda, Chiba 278-8510 (Japan); CSIRO Industrial Physics, P.O. Box 218, Lindfield, New South Wales 2070 (Australia); Department of Chemistry, Warsaw University, Pasteur Street 1, 02-093 Warsaw (Poland)

2006-11-15

290

Titanium Dioxide Coatings Sprayed by a Water-Stabilized Plasma Gun (WSP) with Argon and Nitrogen as the Powder Feeding Gas: Differences in Structural, Mechanical and Photocatalytic Behavior  

NASA Astrophysics Data System (ADS)

Titanium dioxide coatings were sprayed by a water-stabilized plasma gun to form robust self-supporting bodies with a photocatalytically active surface. Agglomerated nanometric powder was used as a feedstock. In one case argon was used as a powder-feeding as well as coating-cooling gas whereas in the other case nitrogen was used. Stainless steel was used as a substrate and the coatings were released after the cooling. Over one millimeter thick self-supporting bodies were studied by XRD, HR-TEM, XPS, Raman spectroscopy, UV-VIS spectrophotometry and photocatalytic tests. Selected tests were done at the surface as well as at the bottom side representing the contact surface with the substrate during the spray process. Porosity was studied by image analysis on polished cross sections where also microhardness was measured. The dominant phase present in the sprayed samples was rutile, whereas anatase was only a minor component. The hydrogen content in the nitrogen-assisted coating was higher, but the character of the optical absorption edge remained the same for both samples. Photoelectron spectroscopy revealed differences in the character of the O1s peak between both samples. The photocatalytic activity was tested by decomposition of acetone at UV illumination, whereas also the end products—CO and CO2—were monitored. The nitrogen-assisted coating was revealed as a more efficient photocatalyst. Certain aspects of a thermal post-treatment on the coatings are discussed as well. Color and electrical conductivity are markedly changed at annealing at 760 °C, whereas only very small changes of the as-sprayed coating character correspond to annealing at 500 °C.

Ctibor, P.; Pala, Z.; Sedlá?ek, J.; Štengl, V.; Píš, I.; Zahoranová, T.; Nehasil, V.

2012-06-01

291

Influence des potentiels d'interaction sur les proprits de transport des plasmas thermiques : exemple d'application le plasma argon hydrogne  

E-print Network

cross-sections. The plasma composition (in LTE) is calculated at atmospheric pressure by the free energy are compared to those of the literature. Revue Phys. Appl. 18 (1983) 51-66 JANVIER 1983, PAGE Classification des opérations de métallurgie extractive [5-8] et à la production de gaz réducteurs ou oxydants à

Paris-Sud XI, Université de

292

ESCAMPIG XXII, Greifswald, Germany, July 15-19, 2014 Analyses of plasma spheroids in dusty plasma by RF discharge in argon  

E-print Network

by Optical Emission Spectroscopy. They are also studied for their interactions with the particle cloud formed, and the other one near the bottom electrode. In our vacuum chamber, we have only one set of spheroids go into the particle cloud. Fig. 1: Plasma spheroids in the discharge. The particle cloud

Boyer, Edmond

293

Measurement of electron temperatures of Argon Plasmas in a High-Density Inductively-Coupled Remote Plasma System by Langmuir Probe and Optical-Emission Spectroscopy  

Microsoft Academic Search

We measured electron density and electron energy distribution function (EEDF) in our reactor by a Langmuir probe. The EEDF of Ar plasma in the reactor could largely be described by the Maxwell-Boltzmann distribution function, but it also contained a fraction (~10-3) of electrons which were much faster (20-40 eV). The peak of the fast-electron tail shifted from E ~ 35

A. Boogaard; A. Y. Kovalgin; A. A. I. Aarnink; R. A. M. Wolters; J. Holleman; I. Brunets; J. Schmitz

2006-01-01

294

Powder evolution at low powers in silane-argon discharge  

SciTech Connect

Powder formation in a 13.56-MHz radio frequency (rf) capacitive glow discharge plasma of silane-argon mixture has been studied by in situ laser light-scattering measurements. The rf power density (P{sub rf}) was varied from 18 to 53 mW/cm{sup 2}. At high P{sub rf} the light scattering occurs all along the discharge and extends even beyond the exit end of the electrodes toward the pumping system. With decreasing P{sub rf} the maximum intensity of the light scattering decreases and the scattering zone shrinks and moves toward the exit end. With P{sub rf}{approx_equal}20 mW/cm{sup 2} a very bright scattering zone only a few centimeters wide appears located at the electrodes outlet. The powders studied by transmission electron microscopy did not show a drastic decrease of their sizes with P{sub rf} though clear coagulation of small particles is observed at high P{sub rf}. In this paper we have tried to link the laser light-scattering evolution with P{sub rf} to various parameters such as the microstructure factor, the deposition rate, the electron mobilityxlifetime product, the density of states, and the minority-carriers diffusion length of the films in an attempt to link the effect the evolution of powder formation to the films properties.

Chaudhuri, P.; Gupta, N. Dutta; Bhaduri, A.; Longeaud, C.; Vignoli, S.; Marty, O. [Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Calcutta 700032 (India); Laboratoire de Genie Electrique de Paris, Unite Mixte de Recherche (UMR) 8507 Centre National de la Recherche Scientifique (CNRS), Ecole Superieure d'Electricite, Universites Paris VI et XI, 11 rue Joliot Curie, Plateau de Moulon, 91190, Gif sur Yvette (France); Laboratoire de Physique de la Matiere Condensee et Nanostructures, Unite Mixte de Recherche (UMR) 5586 Centre National de la Recherche Scientifique (CNRS), Universite Claude Bernard, Batiment Leon Brillouin, La Doua, 69622 Villeurbanne Cedex (France); Laboratoire d'Electronique, Nanotechnologies, Capteurs (EA 3730), Universite Claude Bernard, Batiment Leon Brillouin, La Doua, 69622 Villeurbanne Cedex (France)

2005-08-15

295

Argon/UF6 plasma exhaust gas reconstitution experiments using preheated fluorine and on-line diagnostics. [fissioning uranium plasma core reactor design  

NASA Technical Reports Server (NTRS)

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 system permitted on-line measurements of the UF6 concentration at different locations in the exhaust system. Negligible amounts ( 100 ppm) of UF6 were detected in the axial bypass exhaust duct and the exhaust ducts downstream of the cryogenic trap system used to collect the UF6, thus verifying the overall system efficiency over a range of operating conditions. Use of a porous Monel duct as part of the exhaust duct system, including provision for injection of pure fluorine, provided a viable technique to eliminate uranium compound residue on the inside surface of the exhaust ducts. Typical uranium compound mass deposition per unit area of duct was 2 micron g/sq cm. This porous duct technique is directly applicable to future uranium compound transfer exhaust systems. Throughout these experiments, additional basic data on the corrosion aspects of hot, pressurized UF6/fluorine were also accumulated.

Roman, W. C.

1979-01-01

296

Overview of the coagulation system  

PubMed Central

Coagulation is a dynamic process and the understanding of the blood coagulation system has evolved over the recent years in anaesthetic practice. Although the traditional classification of the coagulation system into extrinsic and intrinsic pathway is still valid, the newer insights into coagulation provide more authentic description of the same. Normal coagulation pathway represents a balance between the pro coagulant pathway that is responsible for clot formation and the mechanisms that inhibit the same beyond the injury site. Imbalance of the coagulation system may occur in the perioperative period or during critical illness, which may be secondary to numerous factors leading to a tendency of either thrombosis or bleeding. A systematic search of literature on PubMed with MeSH terms ‘coagulation system, haemostasis and anaesthesia revealed twenty eight related clinical trials and review articles in last 10 years. Since the balance of the coagulation system may tilt towards bleeding and thrombosis in many situations, it is mandatory for the clinicians to understand physiologic basis of haemostasis in order to diagnose and manage the abnormalities of the coagulation process and to interpret the diagnostic tests done for the same. PMID:25535411

Palta, Sanjeev; Saroa, Richa; Palta, Anshu

2014-01-01

297

Production of high purity argon  

Microsoft Academic Search

This patent describes a process for the production of high purity argon. It comprises: recovering an argon-enriched sidestream from a low pressure column of a cryogenic air separation distillation system comprising a high pressure column, the low pressure column, an argon sidearm column, and a main heat exchanger; passing the argon-enriched sidestream into the argon sidearm column and withdrawing therefrom

J. A. Hopkins; R. M. McGuinnes; R. Agrawal; S. L. Feldman

1991-01-01

298

RADIATION KINETICS AND CHEMICAL REACTIVITY OF BARRIER DISCHARGES IN HUMID ARGON  

E-print Network

RADIATION KINETICS AND CHEMICAL REACTIVITY OF BARRIER DISCHARGES IN HUMID ARGON K.V. Kozlov1,a , E discharge in flowing humid argon at atmospheric pressure. Concentrations of two stable reaction products of H2O decomposition (H2 and O2) in argon plasma were determined experimentally as functions

Boyer, Edmond

299

The Discovery of Argon  

Microsoft Academic Search

IN your translation of Prof. Mendeléeff's interesting paper on the chemical elements (November 17, p. 94) I see that he attributes the discovery of argon and its congeners to Ramsay. Am I not right in believing that it was Lord Rayleigh who discovered argon, and that it was he who gave that impulse to chemistry which Sir William Ramsay has

G. H. Darwin

1904-01-01

300

Autoantibodies to coagulation factors: from pathophysiology to diagnosis and therapy.  

PubMed

Autoantibodies may develop against coagulation factors altering their function or promoting their rapid clearance. In non-congenitally deficient patients, they are usually in association with autoimmune diseases, malignancies, pregnancy or advanced age. The possible development of coagulation factor autoantibodies should be considered when a patient presents with bleeding symptoms without any prior bleeding diathesis. The most common disorder associated with coagulation factor autoantibodies is acquired factor VIII deficiency, which is characterized by hemorrhages involving soft tissues, muscles and skin; hemarthroses are less frequent than in the inherited form. Acquired deficiencies of von Willebrand factor and factor XIII due to autoantibodies are emerging conditions. Autoantibodies to the other coagulation factors may be associated with a wide spectrum of clinical manifestations ranging from minimal or no bleeding to life-threatening conditions. The diagnostic approach begins with global coagulation tests: prothrombin time (PT) and activated partial thromboplastin time (aPTT). In case of prolonged times, mixing studies (typically using normal plasma in a 1:1 proportion) should be performed. Specific factor and inhibitor assays, assessment of lupus anticoagulant and eventually enzyme immunoassays for specific anti-factor antibodies complete the evaluation. A prompt diagnosis of specific coagulation factor inhibitors is mandatory for starting an appropriate treatment aimed at overcoming the deficient factor, in case of bleeding, and, if possible, at the suppression of the autoantibody's production. PMID:23954454

Cugno, Massimo; Gualtierotti, Roberta; Tedeschi, Alberto; Meroni, Pier Luigi

2014-01-01

301

Numerical Modeling of Plasmas in which Nanoparticles Nucleate and Grow  

NASA Astrophysics Data System (ADS)

Dusty plasmas refer to a broad category of plasmas. Plasmas such as argon-silane plasmas in which particles nucleate and grow are widely used in semiconductor processing and nanoparticle manufacturing. In such dusty plasmas, the plasma and the dust particles are strongly coupled to each other. This means that the presence of dust particles significantly affects the plasma properties and vice versa. Therefore such plasmas are highly complex and they involve several interesting phenomena like nucleation, growth, coagulation, charging and transport. Dusty plasma afterglow is equally complex and important. Especially, residual charge on dust particles carries special significance in several industrial and laboratory situations and it has not been well understood. A 1D numerical model was developed of a low-pressure capacitively-coupled plasma in which nanoparticles nucleate and grow. Polydispersity of particle size distributions can be important in such plasmas. Sectional method, which is well known in aerosol literature, was used to model the evolving particle size and charge distribution. The numerical model is transient and one-dimensional and self consistently accounts for nucleation, growth, coagulation, charging and transport of dust particles and their effect on plasma properties. Nucleation and surface growth rates were treated as input parameters. Results were presented in terms of particle size and charge distribution with an emphasis on importance of polydispersity in particle growth and dynamics. Results of numerical model were compared with experimental measurements of light scattering and light emission from plasma. Reasonable qualitative agreement was found with some discrepancies. Pulsed dusty plasma can be important for controlling particle production and/or unwanted particle deposition. In this case, it is important to understand the behavior of the particle cloud during the afterglow following plasma turn-off. Numerical model was modified to self consistently simulate the dynamics and charging of particles during afterglow. It was found that dusty plasma afterglow is dominated by different time scales for electron and ion dynamics. Particle size and charge distribution changes significantly during the afterglow. Finally, a simplified chemistry model was included in dusty plasma numerical model to simulate the dynamics of argon-silane dusty plasma. The chemistry model treats silane dissociation and reactions of silicon hydrides containing up to two silicon atoms. The nucleation rate is equated to rate of formation of anions containing two Si atoms, and a heterogeneous reaction model is used to model particle surface growth. Evolution of particle size and concentration is explained and the importance of variable surface growth rate and nucleation rate is discussed.

Agarwal, Pulkit

302

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

2013-11-01

303

In-flight thermal treatment of soda-lime-silica glass powders for glass production by argon–oxygen induction thermal plasmas  

Microsoft Academic Search

In order to investigate the plasma–particle energy exchange dynamics and optimize the plasma discharge and particle parameters during in-flight thermal treatment of soda-lime-silica glass powders, a plasma–particle interaction model was developed. This model solved the conservation equations to predict the plasma temperature and flow fields, and then calculated the injected individual particle trajectories and temperature histories, and the particle source

M. Mofazzal Hossain; Yaochun Yao; Takayuki Watanabe; Fuji Funabiki; Tetsuji Yano

2009-01-01

304

Microfluidics and Coagulation Biology  

PubMed Central

The study of blood ex vivo can occur in closed or open systems, with or without flow. Microfluidic devices facilitate measurements of platelet function, coagulation biology, cellular biorheology, adhesion dynamics, pharmacology, and clinical diagnostics. An experimental session can accommodate 100s to 1000s of unique clotting events. Using microfluidics, thrombotic events can be studied on defined surfaces of biopolymers, matrix proteins, and tissue factor under constant flow rate or constant pressure drop conditions. Distinct shear rates can be created on a device with a single perfusion pump. Microfluidic devices facilitated the determination of intraluminal thrombus permeability and the discovery that platelet contractility can be activated by a sudden decrease in flow. Microfluidics are ideal for multicolor imaging of platelets, fibrin, and phosphatidylserine and provide a human blood analog to the mouse injury models. Overall, microfluidic advances offer many opportunities for research, drug testing under relevant hemodynamic conditions, and clinical diagnostics. PMID:23642241

Colace, Thomas V.; Tormoen, Garth W.

2014-01-01

305

Thermophoretically modified aerosol brownian coagulation.  

PubMed

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]. PMID:21928988

Arias-Zugasti, Manuel; Rosner, Daniel E

2011-08-01

306

Investigation of nonequilibrium in the initial region of single and binary phase submerged jets of argon  

Microsoft Academic Search

Experiments were conducted to investigate the axial temperature distribution of single and two phase jets of argon plasma with particles of tungsten and titanium. The plasma was generated in an plasmatron whose arc current density varied from 100 to 300 amps producing temperature variations of argon beyond the nozzle section in the range 2000-5000 K. It was found that in

M. V. Zake; V. E. Liepinia

1976-01-01

307

REMOVING TRIHALOMETHANE PRECURSORS BY COAGULATION  

EPA Science Inventory

The removal of trihalomethane precursors by coagulation was studied with low turbidity, low alkalinity waters containing high levels of aquatic humic matter. Jar tests were conducted with synthetic and natural waters using alum, high-molecular-weight polymers, cationic polymers, ...

308

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

309

Roles of argon seeding in energy confinement and pedestal structure in JT-60U  

NASA Astrophysics Data System (ADS)

The mechanism of improving energy confinement with argon seeding at high density has been investigated in JT-60U. Better confinement is sustained at high density by argon seeding accompanied by higher core and pedestal temperatures. The electron density profiles become flatter with increasing density in conventional H-mode plasmas, whereas peaked density profiles are maintained with argon seeding. Density peaking and dilution effects lower the pedestal density at a given averaged density. The pedestal density in the argon seeded plasmas, which is lower than that in plasmas with deuterium puff, enables the pedestal temperature to be higher, whereas the increase in the pedestal pressure with argon seeding is small. High pedestal temperature is a boundary condition for high core temperature through profile stiffness, which leads to better confinement with argon seeding. The density peaking is a key factor of sustaining better confinement in argon seeded H-mode plasmas. The radiative loss power density is predominantly enhanced in the edge region by argon puff. The role of argon seeding in the pedestal characteristics has also been examined. The pedestal width becomes larger continuously with edge collisionality, but is nearly independent of the presence of argon seeding.

Urano, H.; Nakata, M.; Aiba, N.; Kubo, H.; Honda, M.; Hayashi, N.; Yoshida, M.; Kamada, Y.; the JT-60 Team

2015-03-01

310

SERIES ''INTERVENTIONAL PULMONOLOGY'' Edited by J.P. Janssen, M. Noppen and K.F. Rabe Number 1 in this Series Therapeutic bronchoscopy with immediate effect: laser, electrocautery, argon plasma coagulation and stents  

Microsoft Academic Search

Minimally invasive diagnostic and therapeutic approaches in medicine have been applied for a more selective and tailored approach to reduce patients' morbidity and mortality. The efficacy of interventional pulmonology for palliation of patients with central airways obstruction has been established and its curative potential for intralesional treatment of early cancer has raised great interest in current screening programmes. This is

C. T. Bolliger; T. G. Sutedja; J. Strausz; L. Freitag; Lungenklinik Hemer

311

Spectroscopic characterization of femtosecond laser filament in argon gas  

SciTech Connect

We report a spectroscopic approach to measure the plasma density and electron temperature inside a filament created by an intense femtosecond laser pulse in atmospheric pressure argon gas. The technique relies on the proportionality between the Stark broadened argon fluorescence line width due to electron impact and the plasma density, while the electron temperature is determined from the well known Boltzmann plot. The obtained maximum plasma density is about 5.5x10{sup 16} cm{sup -3}, and the electron temperature is about 5800 K. Our method provides a promising and convenient way to characterize the filament for further understanding the fundamental physics and potential applications of filamentation.

Liu, W.; Bernhardt, J.; Theberge, F.; Chin, S. L.; Chateauneuf, M.; Dubois, J. [Institute of Modern Optics, Nankai University, Key Laboratory of Opto-electronic Information Science and Technology, Education Ministry of China, Tianjin 300071 (China); Centre d'Optique, Photonique et Laser (COPL) and Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada); Defence Research and Development Canada--Valcartier, 2459 Pie-XI Blvd. North, Quebec, Quebec, G3J 1X5 Canada (Canada)

2007-08-01

312

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

313

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

314

One-step argon/nitrogen binary plasma jet irradiation of Li4Ti5O12 for stable high-rate lithium ion battery anodes  

NASA Astrophysics Data System (ADS)

Atmospheric pressure Ar/N2 binary plasma jet irradiation has been introduced into the manufacturing process of lithium ions batteries as a facile, green and scalable post-fabrication treatment approach, which enhanced significantly the high-rate anode performance of lithium titanate (Li4Ti5O12). Main emission lines in Ar/N2 plasma measured by optical emission spectroscopy reveal that the dominant excited high-energy species in Ar/N2 plasma are N2*, N2+, N? and Ar?. Sufficient oxygen vacancies have been evidenced by high resolution X-ray photoelectron spectroscopy analysis and Raman spectra. Nitrogen doping has been achieved simultaneously by the surface reaction between pristine Li4Ti5O12 particles and chemically reactive plasma species such as N? and N2+. The variety of Li4Ti5O12 particles on the surface of electrodes after different plasma processing time has been examined by grazing incident X-Ray diffraction. Electrochemical impedance spectra (EIS) confirm that the Ar/N2 atmospheric plasma treatment facilitates Li+ ions diffusion and reduces the internal charge-transfer resistance. The as-prepared Li4Ti5O12 anodes exhibit a superior capacity (132 mAh g-1) and excellent stability with almost no capacity decay over 100 cycles under a high C rate (10C).

Lan, Chun-Kai; Chuang, Shang-I.; Bao, Qi; Liao, Yen-Ting; Duh, Jenq-Gong

2015-02-01

315

Novel peptides that inhibit heparanase activation of the coagulation system.  

PubMed

Heparanase is implicated in cell invasion, tumour metastasis and angiogenesis. It forms a complex and enhances the activity of the blood coagulation initiator - tissue factor (TF). We describe new peptides derived from the solvent accessible surface of TF pathway inhibitor 2 (TFPI-2) that inhibit the heparanase procoagulant activity. Peptides were evaluated in vitro by measuring activated coagulation factor X levels and co-immunoprecipitation. Heparanase protein and/or lipopolysaccharide (LPS) were injected intra-peritoneally and inhibitory peptides were injected subcutaneously in mouse models. Plasma was analysed by ELISA for thrombin-antithrombin complex (TAT), D-dimer as markers of coagulation activation, and interleukin 6 as marker of sepsis severity. Peptides 5, 6, 7, 21 and 22, at the length of 11-14 amino acids, inhibited heparanase procoagulant activity but did not affect TF activity. Injection of newly identified peptides 5, 6 and 7 significantly decreased or abolished TAT plasma levels when heparanase or LPS were pre-injected, and inhibited clot formation in an inferior vena cava thrombosis model. To conclude, the solvent accessible surface of TFPI-2 first Kunitz domain is involved in TF/heparanase complex inhibition. The newly identified peptides potentially attenuate activation of the coagulation system induced by heparanase or LPS without predisposing to significant bleeding tendency. PMID:25030319

Axelman, E; Henig, I; Crispel, Y; Attias, J; Li, J-P; Brenner, B; Vlodavsky, I; Nadir, Y

2014-09-01

316

Influence of argon plasma on the deposition of Al2O3 film onto the PET surfaces by atomic layer deposition  

NASA Astrophysics Data System (ADS)

In this paper, polyethyleneterephthalate (PET) films with and without plasma pretreatment were modified by atomic layer deposition (ALD) and plasma-assisted atomic layer deposition (PA-ALD). It demonstrates that the Al2O3 films are successfully deposited onto the surface of PET films. The cracks formed on the deposited Al2O3 films in the ALD, plasma pretreated ALD, and PA-ALD were attributed to the energetic ion bombardment in plasmas. The surface wettability in terms of water contact angle shows that the deposited Al2O3 layer can enhance the wetting property of modified PET surface. Further characterizations of the Al2O3 films suggest that the elevated density of hydroxyl -OH group improve the initial growth of ALD deposition. Chemical composition of the Al2O3-coated PET film was characterized by X-ray photoelectron spectroscopy, which shows that the content of C 1 s reduces with the growing of O 1 s in the Al2O3-coated PET films, and the introduction of plasma in the ALD process helps the normal growth of Al2O3 on PET in PA-ALD.

Edy, Riyanto; Huang, Xiaojiang; Guo, Ying; Zhang, Jing; Shi, Jianjun

2013-02-01

317

Influence of argon plasma on the deposition of Al2O3 film onto the PET surfaces by atomic layer deposition  

PubMed Central

In this paper, polyethyleneterephthalate (PET) films with and without plasma pretreatment were modified by atomic layer deposition (ALD) and plasma-assisted atomic layer deposition (PA-ALD). It demonstrates that the Al2O3 films are successfully deposited onto the surface of PET films. The cracks formed on the deposited Al2O3 films in the ALD, plasma pretreated ALD, and PA-ALD were attributed to the energetic ion bombardment in plasmas. The surface wettability in terms of water contact angle shows that the deposited Al2O3 layer can enhance the wetting property of modified PET surface. Further characterizations of the Al2O3 films suggest that the elevated density of hydroxyl -OH group improve the initial growth of ALD deposition. Chemical composition of the Al2O3-coated PET film was characterized by X-ray photoelectron spectroscopy, which shows that the content of C 1s reduces with the growing of O 1s in the Al2O3-coated PET films, and the introduction of plasma in the ALD process helps the normal growth of Al2O3 on PET in PA-ALD. PMID:23413804

2013-01-01

318

Thermophysical properties of argon  

SciTech Connect

The entire report consists of tables of thermodynamic properties (including sound velocity, thermal conductivity and diffusivity, Prandtl number, density) of argon at 86 to 400/degree/K, in the form of isobars over 0.9 to 100 bars. (DLC)

Jaques, A.

1988-02-01

319

Coagulation parameters in inflammatory bowel disease  

PubMed Central

Thromboembolic events represent a major cause of morbidity and mortality in patients with inflammatory bowel disease and they may occur both at the gastrointestinal tract and at extraintestinal sites. This study aimed to examine the alterations in coagulation parameters involved at different steps of hemostasis in patients with Crohn’s disease and ulcerative colitis, in comparison with healthy individuals. Fifty-one patients with inflammatory bowel disease and 26 healthy controls were included in this study. Plasma levels of PT, APTT, AT III, plasminogen, fibrinogen, D-dimer, factor V, factor VIII, protein C, protein S, and APCR were measured and factor V Leiden mutation was examined in both patients and controls. Two patients with ulcerative colitis had a history of previous thromboembolic event. Inflammatory bowel disease was associated with significantly higher levels of fibrinogen, PT, factor V, factor VIII, plasminogen and thrombocyte. Protein S, fibrinogen, plasminogen and thrombocyte levels were associated with disease activity, depending on the type of the disease (Crohn’s disease or ulcerative colitis). The coagulation abnormalities detected in this study seems to be a secondary phenomena resulting from the disease process, which is more likely to be associated with a multitude of factors rather than a single abnormality. PMID:24995109

Dolapcioglu, Can; Soylu, Aliye; Kendir, Tulin; Ince, Ali Tuzun; Dolapcioglu, Hatice; Purisa, Sevim; Bolukbas, Cengiz; Sokmen, Haci Mehmet; Dalay, Remzi; Ovunc, Oya

2014-01-01

320

Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol  

NASA Astrophysics Data System (ADS)

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 ?-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, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

2007-06-01

321

Emission spectroscopy combined with a single and a double probe in low-pressure inductively-coupled nitrogen-argon plasmas  

NASA Astrophysics Data System (ADS)

Low-pressure inductively coupled N2-Ar plasmas have been studied to investigate the effects of operating parameters, including the Ar content, applied power, and gas pressure. By means of optical emission spectroscopy and single and double Langmuir probe diagnostic techniques, the evolutions of the plasma density, the electron temperature, and the N2 +, N2, N, and Ar emission lines have been investigated with a discussion of a spatially-averaged global model. From the emission spectra, the ratios of the concentrations of species of interest, and the rotational and the vibrational temperatures of the nitrogen molecules are obtained for various discharge conditions. The rotational and the vibrational temperatures of N2 are found to increase with increasing applied power, pressure, and Ar content, thus making nitrogen plasmas more reactive.

Park, Jae Min; Song, Min A.; Chung, T. H.

2012-08-01

322

Optimization of microalgae coagulation process using chitosan  

Microsoft Academic Search

Here, we report on the harvesting of microalgae cells by coagulation using chitosan and the optimization of this process. Chitosan is a natural and environmentally friendly biopolymer created by the extensive deacetylation of chitin from shrimp, crab and crawfish. Although conventional chemical coagulants such as alum may have negative impacts on human health, the use of chitosan as coagulant is

A. L. Ahmad; N. H. Mat Yasin; C. J. C. Derek; J. K. Lim

2011-01-01

323

Molecular intercommunication between the complement and coagulation systems.  

PubMed

The complement system as well as the coagulation system has fundamental clinical implications in the context of life-threatening tissue injury and inflammation. Associations between both cascades have been proposed, but the precise molecular mechanisms remain unknown. The current study reports multiple links for various factors of the coagulation and fibrinolysis cascades with the central complement components C3 and C5 in vitro and ex vivo. Thrombin, human coagulation factors (F) XIa, Xa, and IXa, and plasmin were all found to effectively cleave C3 and C5. Mass spectrometric analyses identified the cleavage products as C3a and C5a, displaying identical molecular weights as the native anaphylatoxins C3a and C5a. Cleavage products also exhibited robust chemoattraction of human mast cells and neutrophils, respectively. Enzymatic activity for C3 cleavage by the investigated clotting and fibrinolysis factors is defined in the following order: FXa > plasmin > thrombin > FIXa > FXIa > control. Furthermore, FXa-induced cleavage of C3 was significantly suppressed in the presence of the selective FXa inhibitors fondaparinux and enoxaparin in a concentration-dependent manner. Addition of FXa to human serum or plasma activated complement ex vivo, represented by the generation of C3a, C5a, and the terminal complement complex, and decreased complement hemolytic serum activity that defines exact serum concentration that results in complement-mediated lysis of 50% of sensitized sheep erythrocytes. Furthermore, in plasma from patients with multiple injuries (n = 12), a very early appearance and correlation of coagulation (thrombin-antithrombin complexes) and the complement activation product C5a was found. The present data suggest that coagulation/fibrinolysis proteases may act as natural C3 and C5 convertases, generating biologically active anaphylatoxins, linking both cascades via multiple direct interactions in terms of a complex serine protease system. PMID:20870944

Amara, Umme; Flierl, Michael A; Rittirsch, Daniel; Klos, Andreas; Chen, Hui; Acker, Barbara; Brückner, Uwe B; Nilsson, Bo; Gebhard, Florian; Lambris, John D; Huber-Lang, Markus

2010-11-01

324

Activation of the coagulation cascade in C1-inhibitor deficiencies.  

PubMed

Activation of the contact and complement systems in C1-inhibitor deficiencies is thought to contribute to the pathogenesis of angioedema attacks by releasing kinins. Trigger stimuli of attacks may also activate coagulation. This is particularly important because experimental data suggest that thrombin, the main enzyme of the coagulation cascade, increases vascular permeability and can thus influence edema formation. We have studied 19 patients with hereditary angioedema (HAE) during remission, 5 HAE patients during acute attacks, and 6 patients with acquired angioedema (AAE) during remission and during seven attacks. Thirty normal subjects, matched for sex and age, served as controls. Generation of thrombin was measured by enzyme-linked immunosorbent assay (ELISA) as plasma levels of the prothrombin fragment 1 + 2 (F1 + 2); the initiators of the tissue factor and contact coagulation pathways were investigated by measuring plasma levels of activated factor VII (FVIIa) coagulometrically and activated factor XII (FXIIa) by ELISA. Cleavage of high molecular weight kininogen (HK) was evaluated by immunoblotting analysis. F1 + 2 was slightly increased during remission and further significantly increased during attacks in both HAE (P = .0115) and AAE. FVIIa and FXIIa, normal during remission, increased strikingly during attacks in both HAE (P = .0022 and P = .0044) and AAE. During remission, cleaved HK was normal in HAE and high in AAE; during attacks it increased in HAE (P = .0008) and remained elevated in AAE. Our data indicate that in C1-inhibitor deficient patients there is increased generation of thrombin during attacks, with signs of activation of both the contact and tissue factor coagulation pathways. In conclusion, C1-inhibitor deficiency, whether hereditary or acquired, has demonstrable activation of the coagulation and kinin-forming cascades during attacks and that thrombin should be considered a possible contributing factor in the pathogenesis of edema in HAE and AAE. PMID:9129025

Cugno, M; Cicardi, M; Bottasso, B; Coppola, R; Paonessa, R; Mannucci, P M; Agostoni, A

1997-05-01

325

Coagulation factor XIII: A useful polymorphic genetic marker  

Microsoft Academic Search

The plasmas of two groups of subjects were examined for blood coagulation Factor XIII-A (FXIII-A, F13A) by electrophoresis in agarose using a Tris-EDTA-borate buffer to separate the common variants, F13A*1, F13A*2, and F13A*3. Dimeric subunits were visualized in UV light as monodansyl cadaverine bound to casein at the position of the transglutaminase activity representing F13A. One test group consisted of

J. B. Graham; C. J. S. Edgell; Hilari Fleming; K. K. Namboodiri; Bronya J. B. Keats; R. C. Elston

1984-01-01

326

5, 38473872, 2005 Coagulation of  

E-print Network

Coagulation of combustion generated nanoparticles and their measurement behind vehicle engines: can they play. Aigner DLR Institute of Combustion Technology, Pfaffenwaldring 38­40, 70569 Stuttgart, Germany Received.-H. Grotheer (hh.grotheer@dlr.de) © 2005 Author(s). This work is licensed under a Creative Commons License

Paris-Sud XI, Université de

327

The Solar Argon Abundance  

E-print Network

The solar argon abundance cannot be directly derived by spectroscopic observations of the solar photosphere. The solar Ar abundance is evaluated from solar wind measurements, nucleosynthetic arguments, observations of B stars, HII 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 = 10^6 atoms). The recommended abundance for the solar photosphere (on a scale where log N(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.

Katharina Lodders

2007-10-24

328

Study of nuclear recoils in liquid argon with monoenergetic neutrons  

NASA Astrophysics Data System (ADS)

In the framework of developments for liquid argon dark matter detectors we assembled a laboratory setup to scatter neutrons on a small liquid argon target. The neutrons are produced mono-energetically (Ekin = 2.45 MeV) by nuclear fusion in a deuterium plasma and are collimated onto a 3" liquid argon cell operating in single-phase mode (zero electric field). Organic liquid scintillators are used to tag scattered neutrons and to provide a time-of-flight measurement. The setup is designed to study light pulse shapes and scintillation yields from nuclear and electronic recoils as well as from alpha particles at working points relevant for dark matter searches. Liquid argon offers the possibility to scrutinise scintillation yields in noble liquids with respect to the population strength of the two fundamental excimer states. Here we present experimental methods and first results from recent data towards such studies.

Regenfus, C.; Allkofer, Y.; Amsler, C.; Creus, W.; Ferella, A.; Rochet, J.; Walter, M.

2012-07-01

329

Argon ion pollution of the magnetosphere  

NASA Technical Reports Server (NTRS)

Construction of a Solar Power Satellite (SPS) would require the injection of large quantities of propellant to transport material from Low Earth Orbit (LEO) to the construction site at Geostationary Earth Orbit (GEO). This injection, in the form of approx 10 to the 32nd power, 2 KeV argon ions (and associated electrons) per SPS, is comparable to the content of the plasmasphere (approx 10 to the 31st power ions). In addition to the mass deposited, this represents a considerable injection of energy. The injection is examined in terms of a simple model for the expansion of the beam plasma. General features of the subsequent magnetospheric convection of the argon are also examined.

Lopez, R. E.

1985-01-01

330

A Novel Role for Pro-Coagulant Microvesicles in the Early Host Defense against Streptococcus pyogenes  

PubMed Central

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

2013-01-01

331

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

332

A simple collisional radiative model for low-pressure argon discharges  

NASA Astrophysics Data System (ADS)

A simple collisional-radiative model for low-pressure argon discharges is proposed. Using this model and the measured cross section data from recent literature, the relationship between the electron density and some emission line intensities is investigated, resulting in a semi-empirical formula relating the electron density and the emission intensity ratio of argon lines (from levels 3p and 4p). The electron density determined from this model is compared with that from a Langmuir probe in an inductively coupled argon plasma. The application and validity of this model in other kinds of low-pressure argon plasmas, such as capacitively coupled and helicon plasmas, or in discharges containing both argon and other gases are discussed.

Zhu, Xi-Ming; Pu, Yi-Kang

2007-04-01

333

Low-Energy Ionization of Argon Atoms by Argon Atoms  

Microsoft Academic Search

A neutral atomic beam has been used to measure the total ionization cross section for argon atoms incident on low-density argon gas. The beam was produced by symmetric charge transfer of argon ions produced in an electron-impact ion source with 20-eV electrons. Beam energies varied from 30 eV (just below threshold for electron production in ground-state atom collisions) to 2900

Howard C. Hayden; Robert C. Amme

1966-01-01

334

Numerical analysis of the effect of nitrogen and oxygen admixtures on the chemistry of an argon plasma jet operating at atmospheric pressure  

NASA Astrophysics Data System (ADS)

In this paper we study the cold atmospheric pressure plasma jet, called kinpen, operating in Ar with different admixture fractions up to 1% pure {{N}2}, {{O}2} and {{N}2} + {{O}2}. Moreover, the device is operating with a gas curtain of dry air. The absolute net production rates of the biologically active ozone ({{O}3}) and nitrogen dioxide (N{{O}2}) species are measured in the far effluent by quantum cascade laser absorption spectroscopy in the mid-infrared. Additionally, a zero-dimensional semi-empirical reaction kinetics model is used to calculate the net production rates of these reactive molecules, which are compared to the experimental data. The latter model is applied throughout the entire plasma jet, starting already within the device itself. Very good qualitative and even quantitative agreement between the calculated and measured data is demonstrated. The numerical model thus yields very useful information about the chemical pathways of both the {{O}3} and the N{{O}2} generation. It is shown that the production of these species can be manipulated by up to one order of magnitude by varying the amount of admixture or the admixture type, since this affects the electron kinetics significantly at these low concentration levels.

Van Gaens, W.; Iseni, S.; Schmidt-Bleker, A.; Weltmann, K.-D.; Reuter, S.; Bogaerts, A.

2015-03-01

335

The Argon Geochronology Experiment (AGE)  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the Argon Geochronology Experiment (AGE). Potassium-Argon dating is shown along with cosmic ray dating exposure. The contents include a flow diagram of the Argon Geochronology Experiment, and schematic diagrams of the mass spectrometer vacuum system, sample manipulation mechanism, mineral heater oven, and the quadrupole ion trap mass spectrometer. The Laser-Induced Breakdown Spectroscopy (LIBS) Operation with elemental abundances is also described.

Swindle, T. D.; Bode, R.; Fennema, A.; Chutjian, A.; MacAskill, J. A.; Darrach, M. R.; Clegg, S. M.; Wiens, R. C.; Cremers, D.

2006-01-01

336

Simultaneous inductively coupled argon plasma emission spectrometer as a multi-element-specific detector for high pressure liquid chromatography: the determination of arsenic, selenium, and phosphorus compounds  

NASA Astrophysics Data System (ADS)

A Bausch & Lomb-ARL Model 34000 simultaneous inductively coupled plasma (ICP) emission spectrometer was interfaced with a high pressure liquid chromatograph to serve as a multi-element-specific detector. The standard ARL software was modified and a new program written to allow the chromatogram to be displayed graphically on-line. The HPLC-ICP system performance was demonstrated by the separation of arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, phenylarsonic acid, selenite, and phosphate on a reverse-phase column. The detection limit for arsenic is 130 ?g l -1 at 100 ?l injection volumes. The arsenic signals are not dependent on the nature of the arsenic compounds. This HPLC-ICP system allows the quantitative determination of compounds with similar retention times provided they contain different elements determinable by ICP-AES.

Irgolic, Kurt J.; Stockton, R. A.; Chakraborti, D.; Beyer, W.

337

Coagulation and fibrinolysis in capybara ( Hydrochaeris hydrochaeris), a close relative of the guinea-pig ( Cavia porcellus)  

Microsoft Academic Search

Fibrinolytic and coagulation properties of capybara (Hydrochaeris hydrochaeris, LINNAEUS, 1766) plasma were analysed and the results compared to the guinea-pig (Cavia porcellus), a close relative. Capybara fibrinogen was isolated and fibrinolysis of its plasma was carried out in a homologous system and with bovine fibrin. Undiluted plasma did not have fibrinolytic activity on fibrin plates; euglobulins gave a dose-related response.

D. P. S Leitão; A. C. M Polizello; Z Rothschild

2000-01-01

338

Thermophysical properties of multi-shock compressed dense argon  

SciTech Connect

In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ?6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models.

Chen, Q. F., E-mail: chenqf01@gmail.com; Zheng, J.; Gu, Y. J.; Chen, Y. L.; Cai, L. C. [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, P. O. Box 919-102, Mianyang, Sichuan (China)] [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, P. O. Box 919-102, Mianyang, Sichuan (China); Shen, Z. J. [Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-26, Beijing 10086 (China)] [Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-26, Beijing 10086 (China)

2014-02-21

339

A RF Discharge in Argon at Atmospheric Pressure  

Microsoft Academic Search

A dual chamber dischrage is used to create an atmospheric pressure plasma in Argon. The discharge consists of two chambers: one at low pressure (few Torrs) and the other at atmospheric pressure. The chambers are seperated by fused silica window. A RF source(13.56 MHz) is used to create a discharge first in the low pressure chamber which is filled with

Shirshak Dhali; Navin Muthuswamy; Bakul Dave

2001-01-01

340

Argon Welding Inside A Workpiece  

NASA Technical Reports Server (NTRS)

Canopies convert large hollow workpiece into inert-gas welding chamber. Large manifold serves welding chamber for attachment of liner parts in argon atmosphere. Every crevice, opening and passageway provided with argon-rich environment. Weld defects and oxidation dramatically reduced; also welding time reduced.

Morgan, Gene E.

1988-01-01

341

Thyroid-associated autoimmune coagulation disorders  

Microsoft Academic Search

Abnormalities of blood coagulation are not rarely observed in patients with thyroid dysfunctions and may range from subclinical\\u000a laboratory abnormalities to clinically significant hemorrhagic or thrombotic complications. In this review, we summarize the\\u000a current knowledge on thyroid-associated autoimmune coagulation disorders (i.e., autoimmune thrombocytopenic purpura, antiphospholipid\\u000a syndrome, and autoantibodies against coagulation factor VIII) and discuss their laboratory characteristics, clinical impact,\\u000a and

Massimo Franchini; Giuseppe Lippi; Franco Manzato; Pier Paolo Vescovi

2010-01-01

342

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

343

Activation of coagulation by administration of recombinant factor VIIa elicits interleukin 6 (IL6) and IL8 release in healthy human subjects  

Microsoft Academic Search

The activation of coagulation has been shown to contribute to proinflammatory responses in animal and in vitro experiments. Here we report that the activation of coagulation in healthy human subjects by the administration of recombinant factor VIIa also elicits a small but significant increase in the concentrations of interleukin 6 (IL-6) and IL-8 in plasma. This increase was absent when

Evert de Jonge; Philip W. Friederich; George P. Vlasuk; William E. Rote; Margaretha B. Vroom; Marcel Levi; Tom van der Poll

2003-01-01

344

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

345

The Argon Dark Matter Experiment  

E-print Network

The ArDM experiment, a 1 ton liquid argon TPC/Calorimeter, is designed for the detection of dark matter particles which can scatter off the spinless argon nucleus, producing nuclear recoils. These events will be discerned by their light to charge ratio, as well as the time structure of the scintillation light. The experiment is presently under construction and commissioning on surface at CERN. Cryogenic operation and light detection performance was recently confirmed in a test run of the full 1 ton liquid argon target under purely calorimetric operation and with a prototype light readout system. This note describes the experimental concept, the main detector components and presents some first results.

Christian Regenfus

2009-12-15

346

Coagulation Abnormalities in the Trauma Patient: The Role of Point-of-Care Thromboelastography  

PubMed Central

Current recommendations for resuscitation of the critically injured patient are limited by a lack of point-of-care (POC) assessment of coagulation status. Accordingly, the potential exists for indiscriminant blood component administration. Furthermore, although thromboembolic events have been described shortly after injury, the time sequence of post-injury coagulation changes is unknown. Our current understanding of hemostasis has shifted from a classic view, in which coagulation was considered a chain of catalytic enzyme reactions, to the cell-based model (CBM), representing the interplay between the cellular and plasma components of clot formation. Thromboelastography (TEG), a time-sensitive dynamic assay of the viscoelastic properties of blood, closely parallels the CBM, permitting timely, goal-directed restoration of hemostasis via POC monitoring of coagulation status. TEG-based therapy allows for goal-directed blood product administration in trauma, with potential avoidance of the complications resulting from overzealous component administration, as well as the ability to monitor post-injury coagulation status and thromboprophylaxis. This overview addresses coagulation status and thromboprophylaxis management in the trauma patient and the emerging role of POC TEG. PMID:20978993

Gonzalez, Eduardo; Pieracci, Fredric M.; Moore, Ernest E.; Kashuk, Jeffry L.

2015-01-01

347

AUTOSOMAL RECESSIVE DEFICIENCIES OF COAGULATION FACTORS  

Microsoft Academic Search

Deficiencies of coagulation factors that cause a bleeding disorder, other than factor VIII and factor IX, are inherited as autosomal recessive traits and are generally rare, with prevalence in the general population varying between 1 in 500 000 and 1 in 2 000 000. In the last few years, the number of patients with recessively transmitted coagulation deficiencies has increased

F. Peyvandi; R. Asselta; P. M. Mannucci

2001-01-01

348

The ATLAS Liquid Argon Electromagnetic Calorimeter 1  

E-print Network

The ATLAS Liquid Argon Electromagnetic Calorimeter 1 Pascal Pralavorio (for the ATLAS Liquid Argon operation on the LHC in 2005. The collab- oration has chosen a Liquid Argon electromagnetic calorimeter calorimeter is a sampling calorimeter where absorbers are made of lead and liquid argon is the ionising medium

Boyer, Edmond

349

Argon: performance insulation for shared storage servers  

E-print Network

Argon: performance insulation for shared storage servers Matthew Wachs, Michael Abd-El-Malek, Eno in traditional systems and their realization in Ursa Minor's storage server, Argon. Argon uses multi Argon to provide to each client a configurable fraction (e.g., 0.9) of its standalone efficiency

350

Textile wastewater purification through natural coagulants  

NASA Astrophysics Data System (ADS)

A new coagulant obtained through polymerization of Acacia mearnsii de Wild tannin extract has been characterized in the removal of two dangerous dye pollutants: Alizarin Violet 3R and Palatine Fast Black WAN. This coagulant is lab-synthesized according to the etherification of tannins with glycidyltrimethylammonium chloride and formaldehyde and its performance in dye removal in terms of efficiency was high. Reasonably low coagulant dosages (ca. 50 mg L-1) reaches high capacity levels (around 0.8 for Alizarin Violet 3R and 1.6 for Palatine Fast Black WAN mg dye mg-1 of coagulant) and pH and temperature are not extremely affecting variables. The systems coagulant dyes were successfully modeled by applying the Langmuir hypothesis. q max and b parameters were obtained with an adjusted correlation factor ( r 2) above 0.8.

Beltrán-Heredia, J.; Sánchez-Martín, J.; Rodríguez-Sánchez, M. T.

2011-09-01

351

Oxidation Inhibits Iron-Induced Blood Coagulation  

PubMed Central

Blood coagulation under physiological conditions is activated by thrombin, which converts soluble plasma fibrinogen (FBG) into an insoluble clot. The structure of the enzymatically-generated clot is very characteristic being composed of thick fibrin fibers susceptible to the fibrinolytic degradation. However, in chronic degenerative diseases, such as atherosclerosis, diabetes mellitus, cancer, and neurological disorders, fibrin clots are very different forming dense matted deposits (DMD) that are not effectively removed and thus create a condition known as thrombosis. We have recently shown that trivalent iron (ferric ions) generates hydroxyl radicals, which subsequently convert FBG into abnormal fibrin clots in the form of DMDs. A characteristic feature of DMDs is their remarkable and permanent resistance to the enzymatic degradation. Therefore, in order to prevent thrombotic incidences in the degenerative diseases it is essential to inhibit the iron-induced generation of hydroxyl radicals. This can be achieved by the pretreatment with a direct free radical scavenger (e.g. salicylate), and as shown in this paper by the treatment with oxidizing agents such as hydrogen peroxide, methylene blue, and sodium selenite. Although the actual mechanism of this phenomenon is not yet known, it is possible that hydroxyl radicals are neutralized by their conversion to the molecular oxygen and water, thus inhibiting the formation of dense matted fibrin deposits in human blood. PMID:23170793

Pretorius, Etheresia; Bester, Janette; Vermeulen, Natasha; Lipinski, Boguslaw

2013-01-01

352

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

353

The Liquid Argon Purity Demonstrator  

NASA Astrophysics Data System (ADS)

The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

Adamowski, M.; Carls, B.; Dvorak, E.; Hahn, A.; Jaskierny, W.; Johnson, C.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Stancari, M.; Tope, T.; Voirin, E.; Yang, T.

2014-07-01

354

Development of Coagulation Factor Probes for the Identification of Procoagulant Circulating Tumor Cells  

PubMed Central

Metastatic cancer is associated with a hypercoagulable state, and pathological venous thromboembolic disease is a significant source of morbidity and the second leading cause of death in patients with cancer. Here we aimed to develop a novel labeling strategy to detect and quantify procoagulant circulating tumor cells (CTCs) from patients with metastatic cancer. We hypothesize that the enumeration of procoagulant CTCs may be prognostic for the development of venous thrombosis in patients with cancer. Our approach is based on the observation that cancer cells are capable of initiating and facilitating cell-mediated coagulation in vitro, whereby activated coagulation factor complexes assemble upon cancer cell membrane surfaces. Binding of fluorescently labeled, active site-inhibited coagulation factors VIIa, Xa, and IIa to the metastatic breast cancer cell line, MDA-MB-231, non-metastatic colorectal cell line, SW480, or metastatic colorectal cell line, SW620, was characterized in a purified system, in anticoagulated blood and plasma, and in plasma under conditions of coagulation. We conclude that a CTC labeling strategy that utilizes coagulation factor-based fluorescent probes may provide a functional assessment of the procoagulant potential of CTCs, and that this strategy is amenable to current CTC detection platforms. PMID:22973554

Tormoen, Garth W.; Cianchetti, Flor A.; Bock, Paul E.; McCarty, Owen J. T.

2012-01-01

355

Coagulation factor VA2440G causes east Texas bleeding disorder via TFPI?  

PubMed Central

The autosomal dominantly inherited east Texas bleeding disorder is linked to an A2440G variant in exon 13 of the F5 gene. Affected individuals have normal levels of coagulation factor V (FV) activity, but demonstrate inhibition of global coagulation tests. We demonstrated that the A2440G mutation causes upregulation of an alternatively spliced F5 transcript that results in an in-frame deletion of 702 amino acids of the large activation fragment, the B domain. The approximately 250-kDa FV isoform (FV-short), which can be fully activated by thrombin, is present in all A2440G carriers’ plasma (n = 16). FV-short inhibits coagulation through an indirect mechanism by forming a complex with tissue factor pathway inhibitor-? (TFPI?), resulting in an approximately 10-fold increase in plasma TFPI?, suggesting that the TFPI?:FV-short complexes are retained in circulation. The TFPI?:FV-short complexes efficiently inhibit thrombin generation of both intrinsic and extrinsic coagulation pathways. These data demonstrate that the east Texas bleeding disorder–associated F5A2440G leads to the formation of the TFPI?:FV-short complex, which inhibits activation and propagation of coagulation. PMID:23979162

Vincent, Lisa M.; Tran, Sinh; Livaja, Ruzica; Bensend, Tracy A.; Milewicz, Dianna M.; Dahlbäck, Björn

2013-01-01

356

Coagulation factor V(A2440G) causes east Texas bleeding disorder via TFPI?.  

PubMed

The autosomal dominantly inherited east Texas bleeding disorder is linked to an A2440G variant in exon 13 of the F5 gene. Affected individuals have normal levels of coagulation factor V (FV) activity, but demonstrate inhibition of global coagulation tests. We demonstrated that the A2440G mutation causes upregulation of an alternatively spliced F5 transcript that results in an in-frame deletion of 702 amino acids of the large activation fragment, the B domain. The approximately 250-kDa FV isoform (FV-short), which can be fully activated by thrombin, is present in all A2440G carriers' plasma (n = 16). FV-short inhibits coagulation through an indirect mechanism by forming a complex with tissue factor pathway inhibitor-? (TFPI?), resulting in an approximately 10-fold increase in plasma TFPI?, suggesting that the TFPI?:FV-short complexes are retained in circulation. The TFPI?:FV-short complexes efficiently inhibit thrombin generation of both intrinsic and extrinsic coagulation pathways. These data demonstrate that the east Texas bleeding disorder-associated F5(A2440G) leads to the formation of the TFPI?:FV-short complex, which inhibits activation and propagation of coagulation. PMID:23979162

Vincent, Lisa M; Tran, Sinh; Livaja, Ruzica; Bensend, Tracy A; Milewicz, Dianna M; Dahlbäck, Björn

2013-09-01

357

Supplemental Information for Threshold Response of Initiation of Blood Coagulation by Tissue Factor in  

E-print Network

1 Supplemental Information for Threshold Response of Initiation of Blood Coagulation by Tissue plasma (NPP) was purchased from George King Bio-Medical, Inc. (Overland Park, KS). Human whole blood to remove excess BTS. The silanized capillary was then rinsed with ethanol (2 mL) and dried with nitrogen

Ismagilov, Rustem F.

358

Platelet and coagulation factor variations induced in vitro by polyethylene terephthalate (Dacron ®) coated with pyrolytic carbon  

Microsoft Academic Search

The haemocompatibility of polyethylene terephthalate (Dacron®) coated with pyrolytic carbon was examined in vitro, evaluating its capability of inducing adhesion and platelet activation, and of modifying the intrinsic coagulation pathway. Platelet adhesion was evaluated by counting platelets before and after in vitro contact of human plasma with the material under examination. Platelet activation was evaluated by determining platelet factor 4

Elisabetta Cenni; Carla Renata Arciola; Gabriela Ciapetti; Donatella Granchi; Lucia Savarino; Susanna Stea; Daniela Cavedagna; Tiziano Curti; Giuseppina Falsone; Arturo Pizzoferrato

1995-01-01

359

Comparison of a novel polytitanium chloride coagulant with polyaluminium chloride: coagulation performance and floc characteristics.  

PubMed

Polymerized inorganic coagulants are increasingly being used in the water supply and wastewater treatment process, yet there is limited research on the development of polytitanium coagulants. The aim of this study is to synthesize polytitanium chloride (PTC) coagulants and investigate their coagulation behavior and floc characteristics for humic acid removal in comparison to polyaluminum chloride (PAC). The PTC samples with different B (molar ratios of OH/Ti) values were prepared using an instantaneous base-feeding method, employing sodium carbonate as the basification agent. The coagulation efficiency was significantly influenced by different B values. The results suggest that the humic acid removal increased with the increasing B value for PAC, while the inverse trend was observed for PTC. The optimum B value was chosen at 1.0 and 2.0 for PTC and PAC, respectively. Under the optimum coagulant dose and initial solution pH conditions, the PTC coagulant performed better than the PAC coagulant and the floc properties were significantly improved in terms of floc growth rate and floc size. However, the PAC coagulants produced flocs with better floc recoverability than the PTC coagulants. PMID:25291677

Zhao, Y X; Phuntsho, S; Gao, B Y; Yang, Y Z; Kim, J-H; Shon, H K

2015-01-01

360

Resection of meningiomas with implantable microwave coagulation  

SciTech Connect

Implantable microwave coagulation was used to perform resection on 62 patients that had intracranial meningiomas. When 20--60 W microwave power was applied for 15 s, the temperature at the center of the tumor tissue was 43--63 C; 30 mm from the center, the temperature was under 40 C. Histological changes in the center of the tumor showed coagulative necrosis, diminished nuclei, and obliterated blood vessels. The changes at 10--20 mm from the center of the tumor showed coagulative necrosis and degeneration and, 30--50 mm from the center of the tumor, showed normal cell morphology after microwave coagulation. The thermal field in brain tumor has an effective diameter of about 40 mm. No side effects on the normal brain tissues were observed. The amount of blood loss during the operation was minimal while the meningioma was coagulated, especially when the meningioma was located at the skull base or in the parasagittal or cerebral convexity region. After microwave coagulation, the entire tumor could easily be removed. Among the 62 surgically treated cases, gross total tumor excision was 85%. No postoperative complications occurred after microwave coagulation, and there was no operative mortality in the series. The authors believe that this new technique has the advantage of simplicity, less blood loss, and smooth postoperative procedures. Hemostatic effects during the operation are satisfactory, and blood transfusion can be reduced by 50--60%.

Zhou, X.P.; Xie, Q.L.; Liu, J.M.; Yue, Z.J.; Cai, K.H. [Second Military Medical Univ., Shanghai (China)] [Second Military Medical Univ., Shanghai (China)

1996-05-01

361

Transfusion and coagulation management in liver transplantation  

PubMed Central

There is wide variation in the management of coagulation and blood transfusion practice in liver transplantation. The use of blood products intraoperatively is declining and transfusion free transplantations take place ever more frequently. Allogenic blood products have been shown to increase morbidity and mortality. Primary haemostasis, coagulation and fibrinolysis are altered by liver disease. This, combined with intraoperative disturbances of coagulation, increases the risk of bleeding. Meanwhile, the rebalancing of coagulation homeostasis can put patients at risk of hypercoagulability and thrombosis. The application of the principles of patient blood management to transplantation can reduce the risk of transfusion. This includes: preoperative recognition and treatment of anaemia, reduction of perioperative blood loss and the use of restrictive haemoglobin based transfusion triggers. The use of point of care coagulation monitoring using whole blood viscoelastic testing provides a picture of the complete coagulation process by which to guide and direct coagulation management. Pharmacological methods to reduce blood loss include the use of anti-fibrinolytic drugs to reduce fibrinolysis, and rarely, the use of recombinant factor VIIa. Factor concentrates are increasingly used; fibrinogen concentrates to improve clot strength and stability, and prothrombin complex concentrates to improve thrombin generation. Non-pharmacological methods to reduce blood loss include surgical utilisation of the piggyback technique and maintenance of a low central venous pressure. The use of intraoperative cell salvage and normovolaemic haemodilution reduces allogenic blood transfusion. Further research into methods of decreasing blood loss and alternatives to blood transfusion remains necessary to continue to improve outcomes after transplantation. PMID:24876736

Clevenger, Ben; Mallett, Susan V

2014-01-01

362

The Effect of Ozone on Cold Water Coagulation  

Microsoft Academic Search

The application of pre-coagulation ozone in drinking water treatment to provide primary disinfection, has an impact on coagulation and flocculation, and needs to be evaluated further for cold water temperatures, especially when accompanied by episodes of high alkalinity and dissolved organic carbon (DOC). Ozone application to raw water, prior to the addition of coagulants and coagulant aides, was shown to

S. Y. Jasim; S. Ndiongue; B. Johnson; L. Schweitzer; D. Borikar

2008-01-01

363

A simple, general approach of allosteric coagulation enzyme inhibition through monosulfated hydrophobic scaffolds.  

PubMed

Allosteric inhibition of coagulation enzymes offers the advantage of controlled inhibition. In this study, a small library of mono sulfated indole and benzothiazole based molecules was synthesized and screened against the panel of coagulation proteases. The results reveal that selected molecules inhibit the thrombin, factor Xa and factor XIa with moderate potency. Compound 6a was found to have an allosteric mode of inhibition against thrombin. Plasma clotting assays suggest that selected inhibitors 14b, 14c and 14d prolong both prothrombin and activated partial thromboplastin time. Overall, this work presents the newer class of allosteric inhibitors of thrombin and factor XIa with improved aqueous solubility profile. PMID:25453807

Sidhu, Preetpal Singh; Zhou, Qibing; Desai, Umesh R

2014-12-15

364

Antithrombin-III treatment limits disseminated intravascular coagulation in endotoxemia.  

PubMed

Gram-negative septicemia/endotoxemia remains a serious clinical disorder that is often complicated by disseminated intravascular coagulation (DIC). Plasma antithrombin-III (AT-III) levels usually decrease during gram-negative septicemia/endotoxemia, and even moderate decreases in this major inhibitor of the coagulation system are associated with serious DIC. We demonstrated in an earlier study that prophylactic treatment of rats with 250 U/kg of AT-III followed by endotoxin challenge markedly attenuates DIC, indices of organ damage, and metabolic dysfunction. The present study was to determine whether treatment with 250 U/kg AT-III 1 hr after endotoxin challenge would be similarly efficacious. Rats treated with 250 U/kg of AT-III inactivated by human sputum elastase (ATX) served as protein controls. Blood samples for analysis were obtained 4 hr after AT-III or ATX treatment (5 hr after endotoxin challenge). Rats in the ATX treatment group exhibited abnormalities characteristic of endotoxemia, i.e., decreased fibrinogen levels and platelet counts, increases in prothrombin time and activated partial thromboplastin time, elevated serum glutamic oxaloacetic transaminase (SGOT) and alkaline phosphatase (AKP), and hypoglycemia. Treatment with AT-III markedly and significantly (P less than .05) attenuated all of these abnormalities, although survival was not increased. This study strongly suggests that supplementation of plasma AT-III is efficacious after the development of sepsis, although not as efficacious as prophylactic treatment. PMID:2731321

Redens, T B; Emerson, T E

1989-05-01

365

Inhibiting the intrinsic pathway of coagulation with a FXII-targeting RNA Aptamer  

PubMed Central

Background Exposure of the plasma protein factor XII to an anionic surface generates activated factor XII that not only triggers the intrinsic pathway of blood coagulation through the activatio of factor XI, but also mediates various vascular responses through activation of the plasma contact system. While deficiencies of factor XII are not associated with excessive bleeding, thrombosis models in factor deficient animals have suggested that this protein contributes to stable thrombus formation. Therefore, factor XII has emerged as an attractive therapeutic target to treat or prevent pathological thrombosis formation without increasing the risk for hemorrhage. Objectives Utilizing an in vitro directed evolution and chemical biology approach, we sought to isolate a nuclease resistant RNA aptamer that binds specifically to factor XII and directly inhibits factor XII coagulant function. Methods and Results Herein, we describe the isolation and characterization of a high affinity RNA aptamer targeting factor XII/XIIa that dose dependently prolongs fibrin clot formation and thrombin generation in clinical coagulation assays. This aptamer functions as a potent anticoagulant by inhibiting the autoactivation of factor XII, as well as inhibiting intrinsic pathway activation (factor XI activation). However, the aptamer does not affect the factor XIIa-mediated activation of the proinflammatory kallikrein-kinin system (plasma kallikrein activation). Conclusions We have generated a specific and potent factor XII/XIIa aptamer anticoagulant that offers targeted inhibition of discrete macromolecular interactions involved in the activation of the intrinsic pathway of blood coagulation. PMID:23692437

Woodruff, R. S.; Xu, Y.; Layzer, J.; Wu, W.; Ogletreee, M.L.; Sullenger, B.A.

2013-01-01

366

Experimental investigations of plasma perturbation in Thomson scattering applied to thermal plasma diagnostics  

E-print Network

Experimental investigations of plasma perturbation in Thomson scattering applied to thermal plasma ns laser pulses were performed on argon thermal discharge plasma with electron temperature Te 10 000 discharge plasmas 1­5 , laser-induced plasmas 6­9 , pinch plasmas 10­12 , but also to study thermal plasmas

367

21 CFR 864.5400 - Coagulation instrument.  

Code of Federal Regulations, 2010 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5400 Coagulation instrument. (a)...

2010-04-01

368

21 CFR 864.5400 - Coagulation instrument.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5400 Coagulation instrument. (a)...

2011-04-01

369

Coagulation testing in the perioperative period  

PubMed Central

Perioperative coagulation management is a complex task that has a significant impact on the perioperative journey of patients. Anaesthesia providers play a critical role in the decision-making on transfusion and/or haemostatic therapy in the surgical setting. Various tests are available in identifying coagulation abnormalities in the perioperative period. While the rapidly available bedside haemoglobin measurements can guide the transfusion of red blood cells, blood product administration is guided by many in vivo and in vitro tests. The introduction of newer anticoagulant medications and the implementation of the modified in vivo coagulation cascade have given a new dimension to the field of perioperative transfusion medicine. A proper understanding of the application and interpretation of the coagulation tests is vital for a good perioperative outcome. PMID:25535418

Thiruvenkatarajan, Venkatesan; Pruett, Ashlee; Adhikary, Sanjib Das

2014-01-01

370

ARSENIC REMOVAL BY SOFTENING AND COAGULATION  

EPA Science Inventory

Drinking water regulations for arsenic (As) and disinfection by-product precursor materials (measured as TOC) are becoming increasingly stringent. Among the modifications to conventional treatment that can improve removal of As and TOC, precipitative softening and coagulation are...

371

Coagulation of Oil in Water Using Sawdust and Bentonite and the Formation of a Floating Coagulated Material  

E-print Network

is relevant to oil-spill cleanups, water treatment, and water resource management. The coagulation of oil-7870.0000725. © 2013 American Society of Civil Engineers. CE Database subject headings: Coagulation; Oil spills; WaterCoagulation of Oil in Water Using Sawdust and Bentonite and the Formation of a Floating Coagulated

Chung, Deborah D.L.

372

JOURNAL DE PHYSIQUE CoZZoque C7, suppZ6rnent au n07, Tome 40, JuiZZet 1979, page C7-47 INFLUENCE OF PERTURBATIONON POPULATIONPROCESSESOF 4p ARGON LEVELS  

E-print Network

OF PERTURBATIONON POPULATIONPROCESSESOF 4p ARGON LEVELS S. DjeniYe and J.M. Labat. Department of Physics and Meteorology and Institute of Physics, 11000 Beograd, YugosZavia. Population of argon 4p levels in a decaying plasma was found to be predominan- tly due to the dissociative recombination of molecular argon ions

Boyer, Edmond

373

Gas heating in low-pressure microwave argon discharges  

Microsoft Academic Search

Both an energy balance equation and a collisional-radiative model were developed in order to discover which process is responsible for gas heating in a low-pressure argon discharge. In this way, for a wide range of plasma conditions, the space-charge field contribution to gas heating was found to be negligible compared to that resulting from elastic collisional processes, although the value

A. Palmero; J. Cotrino; C. Lao; A. R. González-Elipe

2002-01-01

374

Dust Coagulation in Protoplanetary Accretion Disks  

NASA Technical Reports Server (NTRS)

The time evolution of dust particles in circumstellar disk-like structures around protostars and young stellar objects is discussed. In particular, we consider the coagulation of grains due to collisional aggregation. The coagulation of the particles is calculated by solving numerically the non-linear Smoluchowski equation. The different physical processes leading to relative velocities between the grains are investigated. The relative velocities may be induced by Brownian motion, turbulence and drift motion. Starting from different regimes which can be identified during the grain growth we also discuss the evolution of dust opacities. These opacities are important for both the derivation of the circumstellar dust mass from submillimeter/millimeter continuum observations and the dynamical behavior of the disks. We present results of our numerical studies of the coagulation of dust grains in a turbulent protoplanetary accretion disk described by a time-dependent one-dimensional (radial) alpha-model. For several periods and disk radii, mass distributions of coagulated grains have been calculated. From these mass spectra, we determined the corresponding Rosseland mean dust opacities. The influence of grain opacity changes due to dust coagulation on the dynamical evolution of a protostellar disk is considered. Significant changes in the thermal structure of the protoplanetary nebula are observed. A 'gap' in the accretion disk forms at the very frontier of the coagulation, i.e., behind the sublimation boundary in the region between 1 and 5 AU.

Schmitt, W.; Henning, Th.; Mucha, R.

1996-01-01

375

On Coagulation and the Stellar Mass Spectrum  

NASA Astrophysics Data System (ADS)

The importance of coagulation in the making of the stellar mass spectrum is studied using two coagulation indicators and the model of Lejeune and Bastien. A search is made for correlations between these indicators and the physical characteristics of the four types of stellar groups investigated here: open clusters (54 cases), OB associations (16 cases), globular clusters (16 cases), and galaxies (13 cases). Although (1) coagulation is certainly not the only physical process which determines eventually the stellar mass spectrum and (2) the Lejeune and Bastien analytical solution describes only approximately the physics involved, we found that it fits the mass spectra extremely well. The fits are definitely much better than the usual power-law fits. The results show that coagulation seems to be pretty independent of the conditions at which it takes place. The means of the coagulation indicators for each type of stellar group are found to be quite close to each other (within the limits of uncertainty), which adds more weight to these results. It is also found that the effects of coagulation are difficult to show, at least for stellar groups with ages greater than econg 107 yr. A method of assessing the amount of mass loss by the cluster is also described.

Allen, Eric J.; Bastien, Pierre

1995-10-01

376

Removal of silver nanoparticles by coagulation processes.  

PubMed

Commercial use of silver nanoparticles (AgNPs) will lead to a potential route for human exposure via potable water. Coagulation followed by sedimentation, as a conventional technique in the drinking water treatment facilities, may become an important barrier to prevent human from AgNP exposures. This study investigated the removal of AgNP suspensions by four regular coagulants. In the aluminum sulfate and ferric chloride coagulation systems, the water parameters slightly affected the AgNP removal. However, in the poly aluminum chloride and polyferric sulfate coagulation systems, the optimal removal efficiencies were achieved at pH 7.5, while higher or lower of pH could reduce the AgNP removal. Besides, the increasing natural organic matter (NOM) would reduce the AgNP removal, while Ca(2+) and suspended solids concentrations would also affect the AgNP removal. In addition, results from the transmission electron microscopy and X-ray diffraction showed AgNPs or silver-containing nanoparticles were adsorbed onto the flocs. Finally, natural water samples were used to validate AgNP removal by coagulation. This study suggests that in the case of release of AgNPs into the source water, the traditional water treatment process, coagulation/sedimentation, can remove AgNPs and minimize the silver ion concentration under the well-optimized conditions. PMID:23973474

Sun, Qian; Li, Yan; Tang, Ting; Yuan, Zhihua; Yu, Chang-Ping

2013-10-15

377

Bright hydrogen-light source due to a resonant energy transfer with strontium and argon ions  

Microsoft Academic Search

A plasma called a resonant transfer (rt) plasma formed with a low field (1 V cm-1), at low temperatures (e.g. ?103 K), from atomic hydrogen generated at a tungsten filament and strontium which was vapourized by heating the metal. Strong vacuum ultraviolet emission was observed that increased with the addition of argon, but not when sodium, magnesium or barium replaced

Randell L Mills; Mark Nansteel; Paresh C Ray

2002-01-01

378

Bright hydrogen-light source due to a resonant energy transfer with strontium and argon ions  

Microsoft Academic Search

A plasma called a resonant transfer (rt) plasma formed with a low field (1 V cm-1), at low temperatures (e.g. ≈103 K), from atomic hydrogen generated at a tungsten filament and strontium which was vapourized by heating the metal. Strong vacuum ultraviolet emission was observed that increased with the addition of argon, but not when sodium, magnesium or barium replaced

Randell L. Mills; Mark Nansteel; Paresh C. Ray

2002-01-01

379

Evidence for factor IX-independent roles for factor XIa in blood coagulation  

PubMed Central

Background Factor (f) XIa is traditionally assigned a role in fIX activation during coagulation. However, recent evidence suggests this protease may have additional plasma substrates. Objective To determine if fXIa promotes thrombin generation and coagulation in plasma in the absence of fIX, and to determine if fXI deficiency produces an antithrombotic effect in mice independent of fIX. Methods FXIa, fXIa variants, and anti-fXIa antibodies were tested for their effects on plasma coagulation and thrombin generation in the absence of fIX, and for their effects on activation of purified coagulation factors. Mice with combined fIX and fXI deficiency were compared to mice lacking either fIX or fXI in an arterial thrombosis model. Results In fIX-deficient plasma, fXIa induced thrombin generation and anti-fXIa antibodies prolonged clotting times. This process involved fXIa-mediated conversion of fX and fV to their active forms. Activation of fV by fXIa required the A3 domain on the fXIa heavy chain, while activation of fX did not. FX activation by fXIa, unlike fIX activation, was not a calcium-dependent process. Mice lacking both fIX and fXI were more resistance to ferric chloride-induced carotid artery occlusion than fXI-deficient or fIX-deficient mice. Conclusion In addition to its predominant role as an activator of fIX, fXIa may contribute to coagulation by activating fX and fV. As the latter reactions do not require calcium, they may make important contributions to in vitro clotting assays triggered by contact activation. The reactions may be relevant to fXIa's roles in hemostasis and in promoting thrombosis. PMID:24152424

Matafonov, Anton; Cheng, Qiufang; Geng, Yipeng; Verhamme, Ingrid M.; Umunakwe, Obi; Tucker, Erik I.; Sun, Mao-fu; Serebrov, Vladimir; Gruber, Andras; Gailani, David

2014-01-01

380

Sonoluminescing Air Bubbles Rectify Argon  

SciTech Connect

The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water soluble gases implies that strongly forced air bubbles eventually consist of pure argon. Thus it is the partial argon (or any other inert gas) pressure which is relevant for stability. The theory provides quantitative explanations for many aspects of SBSL. {copyright} {ital 1997} {ital The American Physical Society}

Lohse, D.; Hilgenfeldt, S. [Fachbereich Physik der Universitaet Marburg, Renthof 6, 35032 Marburg (Germany)] [Fachbereich Physik der Universitaet Marburg, Renthof 6, 35032 Marburg (Germany); Brenner, M.P. [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Dupont, T.F. [Department of Computer Science, University of Chicago, Chicago, Illinois 60637 (United States)] [Department of Computer Science, University of Chicago, Chicago, Illinois 60637 (United States); Johnston, B. [Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States)] [Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States)

1997-02-01

381

Coagulation algorithms with size binning  

NASA Technical Reports Server (NTRS)

The Smoluchowski equation describes the time evolution of an aerosol particle size distribution due to aggregation or coagulation. Any algorithm for computerized solution of this equation requires a scheme for describing the continuum of aerosol particle sizes as a discrete set. One standard form of the Smoluchowski equation accomplishes this by restricting the particle sizes to integer multiples of a basic unit particle size (the monomer size). This can be inefficient when particle concentrations over a large range of particle sizes must be calculated. Two algorithms employing a geometric size binning convention are examined: the first assumes that the aerosol particle concentration as a function of size can be considered constant within each size bin; the second approximates the concentration as a linear function of particle size within each size bin. The output of each algorithm is compared to an analytical solution in a special case of the Smoluchowski equation for which an exact solution is known . The range of parameters more appropriate for each algorithm is examined.

Statton, David M.; Gans, Jason; Williams, Eric

1994-01-01

382

Controlling difficult pelvic bleeding with argon beam coagulator during laparoscopic ultra low anterior resection.  

PubMed

In recent years, the standard of care for lower rectal tumors has developed to include a total mesorectal excision, which provides optimal long-term results. There has been debate with regard to the best approach for lower rectal tumors, conventional open versus less invasive procedures. As the trend toward less invasive surgical procedures progresses, similar complications, which are seen in open cases, are being encountered, such as the notorious presacral fascia bleed. These are small vessels, which are difficult to locate and control. Surgical literature suggests different methods during laparoscopic procedures. These include: placing lap pads and holding pressure, placing saline bag, placing tacks, using bone wax, and electrocautry at different settings. We present a case of a 57-year-old male, positive for lymph node disease, who underwent laparoscopic ultra low anterior resection with total mesorectal excision and protective loop ileostomy. PMID:21304367

Kandeel, Ahmed; Meguid, Ahmed; Hawasli, Abdelkader

2011-02-01

383

Argon SDC detector cryogenic design  

SciTech Connect

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 piping, headers, dewar elevations, etc. This will afford the designer considerable latitude to change the design as required to meet other system requirements. For example, dewar elevation above the detector and horizontal distance to the detector could be varied to meet hall-space requirements. The point design shows a simple system with only one argon supply-and-return pipe to the detector. No nitrogen cooling is required at the detector. No seals or piping (except for an open supply and return header) are required in the detector and a minimum, of baffling to director argon flow is required. No thermal insulation is required to protect modules from pre-amp heat. A simple temperature control technique for the argon loop using a single nitrogen dewar and heat exchanger is shown.

Slack, D.S.

1991-10-25

384

Sonoluminescing Air Bubbles Rectify Argon  

Microsoft Academic Search

The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water soluble gases implies that strongly forced air bubbles eventually consist of pure argon. Thus

Detlef Lohse; Michael P. Brenner; Todd F. Dupont; Sascha Hilgenfeldt; Blaine Johnston

1997-01-01

385

Undriven periodic plasma oscillation in electron cyclotron resonance Ar plasma  

Microsoft Academic Search

We report experimental observation of periodic oscillation in a steady state electron cyclotron resonance argon plasma that is not driven by extra periodic forces. We interpret the oscillation according to the predator-prey model, which is a nonlinear plasma-neutral coupling in the plasma production region. The oscillation is observed in a narrow plasma parameter window and is evidence for neutral density

Pyung-Woo Lee; Sang-Won Lee; Hong-Young Chang

1996-01-01

386

Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes  

PubMed Central

Cryo-electron microscopy (Cryo-EM)1 is a powerful approach to investigate the functional structure of proteins and complexes in a hydrated state and membrane environment2. Coagulation Factor VIII (FVIII)3 is a multi-domain blood plasma glycoprotein. Defect or deficiency of FVIII is the cause for Hemophilia type A - a severe bleeding disorder. Upon proteolytic activation, FVIII binds to the serine protease Factor IXa on the negatively charged platelet membrane, which is critical for normal blood clotting4. Despite the pivotal role FVIII plays in coagulation, structural information for its membrane-bound state is incomplete5. Recombinant FVIII concentrate is the most effective drug against Hemophilia type A and commercially available FVIII can be expressed as human or porcine, both forming functional complexes with human Factor IXa6,7. In this study we present a combination of Cryo-electron microscopy (Cryo-EM), lipid nanotechnology and structure analysis applied to resolve the membrane-bound structure of two highly homologous FVIII forms: human and porcine. The methodology developed in our laboratory to helically organize the two functional recombinant FVIII forms on negatively charged lipid nanotubes (LNT) is described. The representative results demonstrate that our approach is sufficiently sensitive to define the differences in the helical organization between the two highly homologous in sequence (86% sequence identity) proteins. Detailed protocols for the helical organization, Cryo-EM and electron tomography (ET) data acquisition are given. The two-dimensional (2D) and three-dimensional (3D) structure analysis applied to obtain the 3D reconstructions of human and porcine FVIII-LNT is discussed. The presented human and porcine FVIII-LNT structures show the potential of the proposed methodology to calculate the functional, membrane-bound organization of blood coagulation Factor VIII at high resolution. PMID:24961276

Miller, Jaimy; Dalm, Daniela; Koyfman, Alexey Y.; Grushin, Kirill; Stoilova-McPhie, Svetla

2014-01-01

387

Magnetic particle imaging of blood coagulation  

NASA Astrophysics Data System (ADS)

We investigated the feasibility of visualizing blood coagulation using a system for magnetic particle imaging (MPI). A magnetic field-free line is generated using two opposing neodymium magnets and transverse images are reconstructed from the third-harmonic signals received by a gradiometer coil, using the maximum likelihood-expectation maximization algorithm. Our MPI system was used to image the blood coagulation induced by adding CaCl2 to whole sheep blood mixed with magnetic nanoparticles (MNPs). The "MPI value" was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. MPI values were significantly smaller for coagulated blood samples than those without coagulation. We confirmed the rationale of these results by calculating the third-harmonic signals for the measured viscosities of samples, with an assumption that the magnetization and particle size distribution of MNPs obey the Langevin equation and log-normal distribution, respectively. We concluded that MPI can be useful for visualizing blood coagulation.

Murase, Kenya; Song, Ruixiao; Hiratsuka, Samu

2014-06-01

388

Magnetic particle imaging of blood coagulation  

SciTech Connect

We investigated the feasibility of visualizing blood coagulation using a system for magnetic particle imaging (MPI). A magnetic field-free line is generated using two opposing neodymium magnets and transverse images are reconstructed from the third-harmonic signals received by a gradiometer coil, using the maximum likelihood-expectation maximization algorithm. Our MPI system was used to image the blood coagulation induced by adding CaCl{sub 2} to whole sheep blood mixed with magnetic nanoparticles (MNPs). The “MPI value” was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. MPI values were significantly smaller for coagulated blood samples than those without coagulation. We confirmed the rationale of these results by calculating the third-harmonic signals for the measured viscosities of samples, with an assumption that the magnetization and particle size distribution of MNPs obey the Langevin equation and log-normal distribution, respectively. We concluded that MPI can be useful for visualizing blood coagulation.

Murase, Kenya, E-mail: murase@sahs.med.osaka-u.ac.jp; Song, Ruixiao; Hiratsuka, Samu [Department of Medical Physics and Engineering, Division of Medical Technology and Science, Faculty of Health Science, Graduate School of Medicine, Osaka University, Osaka 565-0871 (Japan)

2014-06-23

389

Microwave diagnostics of atmospheric plasmas  

NASA Astrophysics Data System (ADS)

Plasma treatment of biological tissues has tremendous potential due to the wide range of applications. Most plasmas have gas temperatures which greatly exceed room temperature. These are often utilized in electro-surgery for cutting and coagulating tissue. Another type of plasma, referred to as cold atmospheric plasma, or CAP, is characterized by heavy particle temperatures which are at or near room temperature. Due to this lack of thermal effect, CAP may provide less invasive medical procedures. Additionally, CAP have been demonstrated to be effective at targeting cancer cells while minimizing damage to the surrounding tissue. A recently fabricated Microwave Electron Density Device (MEDD) utilizes microwave scattering on small atmospheric plasmas to determine the electron plasma density. The MEDD can be utilized on plasmas which range from a fraction of a millimeter to several centimeters at atmospheric pressure when traditional methods cannot be applied. Microwave interferometry fails due to the small size of the plasma relative to the microwave wavelength which leads to diffraction and negligible phase change; electrostatic probes introduce very strong perturbation and are associated with difficulties of application in strongly-collisional atmospheric conditions; and laser Thomson scattering is not sensitive enough to measure plasma densities less than 1012 cm-3. The first part of this dissertation provides an overview of two types of small atmospheric plasma objects namely CAPs and plasmas utilized in the electro-surgery. It then goes on to describe the fabrication, testing and calibration of the MEDD facility. The second part of this dissertation is focused on the application of the MEDD and other diagnostic techniques to both plasma objects. A series of plasma images that illustrate the temporal evolution of a discharge created by an argon electrosurgical device operating in the coagulation mode and its behavior was analyzed. The discharge of the argon electrosurgical system was studied using an Intensified Charge-Coupled Device (ICCD) and the MEDD. The plasma density was measured and found to be in the range of (7.5-9.5) x 1015 cm-3 for applied powers of 15-60 Watts. The discharge can be classified as a glow discharge of alternating current with a contracted positive column. The discharge ignites every half-wave of the driving voltage when voltage increases above the breakdown threshold of about 300 Volts and is interrupted at the end of each half-wave when the voltage approaches zero. Additionally, it was shown that the plasma discharges on the target object during the positive half-wave of the voltage. The power distribution was also analyzed. It was found that 60-70% of the input power is delivered into the tissue and the remaining 30-40% is consumed by the plasma column between the electrosurgical probe and tissue. The application of the MEDD to a helium CAP revealed the temporal dynamics of the discharge. It was observed that streamer development associated with the measured plasma density peak is developing on the decaying part of the main inter-electrode discharge. The third part of the dissertation focuses on the simulation of a helium CAP. A one-dimensional model of a helium CAP was used to simulate twenty-one oxygen, helium, and nitrogen species. One hundred and forty reactions were successfully used. The predicted maximum and average densities of the species were tabulated. Graphs of the species densities were presented showing the change in densities with respect to the radius of the CAP. The plasma bullets can be seen via these graphs, with most species displaying maximum densities at a radius which is not the center of the CAP. This shows that the plasma bullets are a disk-like structure at the moment of time presented. Values of E/p were varied from 20 -- 30 volts/cm Torr. Based on experimental results of moments in time with which the maximum plasma density occurs, this data can be used to predict the actual E/p values for future experiments.

Scott, David

390

Advances in the treatment of inherited coagulation disorders.  

PubMed

Inherited coagulation disorders constitute a broad spectrum of coagulation factor deficiencies that include X-linked factor (F)VIII or FIX deficiency that causes haemophilia, and autosomal recessive disorders producing heterogeneous deficiencies in fibrinogen (FI), prothrombin (FII), FV, FVII, FX, FXI, FXIII and combined FV+FVIII. Significant advances in treatments for patients with congenital haemophilia A (FVIII deficiency) and B (FIX deficiency) over the last two decades have resulted from improvements in the production, availability and patient access to factor replacement products. Translation of advances in biotechnology, namely recombinant protein technology, targeted protein modifications to improve function and potentially reduce immunogenicity, and advanced formulations to optimize bioavailability and sustain activity offer promisingly new treatments for haemophilia as well as recessively inherited bleeding disorders in patients who otherwise have few therapeutic options. Though a theoretical risk remains for blood-borne viral infections with pooled plasma-derived products, this concern has diminished with breakthroughs in purification and viral inactivation methods. Development of inhibitory antibodies is still the most daunting problem for patients with inherited bleeding disorders, complicating treatment approaches to control and prevent bleeding, and posing risks for allergic and anaphylactic reactions in susceptible patients. The objectives of this review are to (i) highlight emerging advances in hemostatic therapies that are bioengineered to improve pharmacokinetic properties and bioavailability, sustain functional activity, and possibly eliminate immunogenicity of recombinant factor proteins; and (ii) present an overview of key clinical trials of novel factor products currently in the development pipeline. PMID:23600951

Escobar, M A

2013-09-01

391

Coagulation and fragmentation dynamics of inertial particles  

E-print Network

Inertial particles suspended in many natural and industrial flows undergo coagulation upon collisions and fragmentation if their size becomes too large or if they experience large shear. Here we study this coagulation-fragmentation process in time-periodic incompressible flows. We find that this process approaches an asymptotic, dynamical steady state where the average number of particles of each size is roughly constant. We compare the steady-state size distributions corresponding to two fragmentation mechanisms and for different flows and find that the steady state is mostly independent of the coagulation process. While collision rates determine the transient behavior, fragmentation determines the steady state. For example, for fragmentation due to shear, flows that have very different local particle concentrations can result in similar particle size distributions if the temporal or spatial variation of shear forces is similar.

Jens C. Zahnow; Rafael D. Vilela; Ulrike Feudel; Tamás Tél

2009-08-20

392

Fibrinolysis and the control of blood coagulation  

PubMed Central

Fibrin plays an essential role in hemostasis as both the primary product of the coagulation cascade and the ultimate substrate for fibrinolysis. Fibrinolysis efficiency is greatly influenced by clot structure, fibrinogen isoforms and polymorphisms, the rate of thrombin generation, the reactivity of thrombus-associated cells such as platelets, and the overall biochemical environment. Regulation of the fibrinolytic system, like that of the coagulation cascade, is accomplished by a wide array of cofactors, receptors, and inhibitors. Fibrinolytic activity can be generated either on the surface of a fibrin-containing thrombus, or on cells that express profibrinolytic receptors. In a widening spectrum of clinical disorders, acquired and congenital defects in fibrinolysis contribute to disease morbidity, and new assays of global fibrinolysis now have potential predictive value in multiple clinical settings. Here, we summarize the basic elements of the fibrinolytic system, points of interaction with the coagulation pathway, and some recent clinical advances. PMID:25294122

Chapin, John C.; Hajjar, Katherine A.

2014-01-01

393

Particle-induced oscillations in inductively coupled plasmas  

Microsoft Academic Search

The feedback between particles and the heating of an inductively coupled plasma (ICP) from argon is investigated. The ICP is heated by a pancake coil antenna, which is coupled to the plasma via a dielectric window. Particles are generated by injecting a pulse of acetylene for a few seconds into an argon plasma. Afterwards, the emission of the ICP starts

Achim von Keudell; Martin Bauer

2004-01-01

394

[Relationship among coagulation effect of Al-based coagulant, content and speciation of residual aluminum].  

PubMed

The application of AlCl3, Al2 (SO4)3 and poly-aluminum chloride (PAC) in humic acid-kaolin simulated water was studied in this article. It is intended to discuss the relationship among coagulation effect of Al-based coagulants in humic acid-kaolin simulated water and content and speciation of residual aluminum. It was found that, the turbidity removal efficiency and UV254 removal efficiency could reach about 90% at the tested dosage. At higher dosage, PAC gave better coagulation effect. The residual total aluminum content and residual aluminum ratio of PAC, which was 0.9 mg/L and - 3.0% or so respectively, were greatly lower than those of AlCl3 and Al2 (SO4)3. The residual total dissolved aluminum was the predominant content in the effluent after coagulation and sedimentation by the three Al-based coagulants. For the total dissolved aluminum, the proportion of dissolved organic aluminum was significantly higher than that of other aluminum speciation. With respect to humic acid-kaolin simulated water, the content of residual total aluminum in the effluent after coagulation and sedimentation by PAC decreased obviously compared to AlCl3 and Al2 (SO4)3. PAC could effectively decrease the content of residual dissolved aluminum speciation which has higher toxicity. The content of residual total dissolved aluminum in the effluent after coagulation and sedimentation by PAC was about 0.6 mg/L. PMID:20698270

Yang, Zhong-Lian; Gao, Bao-Yu; Yue, Qin-Yan; Jiang, Yi-Shuai

2010-06-01

395

Effect of Argon Addition on Morphology and Structure of Diamond Films (from Microcrystalline to Nanocrystalline)  

NASA Astrophysics Data System (ADS)

Micro-/nanocrystalline diamond films deposited in Ar/H2/CH4 microwave plasmas have been studied, with argon flow rates in the range of 70-100 sccm. The effects of argon addition on morphology, surface roughness, quality and structure were investigated by scanning electron microscopy, surface profiler, Raman spectrometer and X-ray diffraction (XRD). It is demonstrated that when the argon flow rate is 70 sccm or 75 sccm, well-faceted polycrystalline diamond films can be grown at a low substrate temperature less than 610 °C. With the increase in the argon flow rate, the smooth crystallographic planes disappear gradually. Instead, rough crystallographic planes made up of small aggregates begin to take shape, resulting from the increase in the secondary nucleation rate. Nanocrystalline diamond films were obtained at a flow rate of 100 sccm, and all of the prepared diamond films were smooth, with a surface roughness (Ra) less than 20 nm. Raman analyses reveal that the amount of amorphous carbon increases significantly with the increase in argon flow. The results of XRD show that crystalline size and preferential orientation of diamond films depend on the argon content in the plasmas. supported by National Natural Science Foundation of China (No. 11175137)

LV, Lin; WANG, Jianhua; WENG, Jun; CUI, Xiaohui; ZHANG, Ying

2015-03-01

396

Determination of the rate coefficient of the electron-impact excitation from the argon resonance states (1s2 and 1s4) to 2p states by the emission line ratio in an afterglow plasma  

NASA Astrophysics Data System (ADS)

The rate coefficients of electron-impact excitation from argon 1s2 and 1s4 (resonance states) to 2p states are determined in the electron temperature (Te) range of 0.5–1.1 eV. This is achieved by using a population model for Ar(2p) and measured parameters in the afterglow of an rf (60 MHz) pulsed capacitive discharge. These parameters include the densities of the 2p states (optical emission spectroscopy), the densities of the four argon 1s states (diode laser absorption), and Te (a Langmuir probe and a line-ratio technique), for discharges with two gas mixtures: Ar(60 mTorr)/O2(2 mTorr) and Ar(60 mTorr)/Xe(1.8 mTorr). It is found that the rate coefficients obtained in this work agree well with those from the cross sections by a large-scale R-matrix calculation reported recently by Zatsarinny et al (2004 J. Phys. B: At. Mol. Opt. Phys. 37 4693, 2014 Phys. Rev. A 89 022706).

Cheng, Zhi-Wen; Zhu, Xi-Ming; Liu, Fei-Xiang; Pu, Yi-Kang

2015-04-01

397

Boltzmann expansion in a radiofrequency conical helicon thruster operating in xenon and argon  

SciTech Connect

A low pressure ({approx}0.5 mTorr in xenon and {approx}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. [Space Plasma, Power and Propulsion Laboratory, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)] [Space Plasma, Power and Propulsion Laboratory, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Takahashi, K. [Space Plasma, Power and Propulsion Laboratory, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia) [Space Plasma, Power and Propulsion Laboratory, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Department of Electrical Engineering, Tohoku University, Sendai 980-9579 (Japan)

2013-06-03

398

Computer-assisted interstitial laser coagulation for BPH  

NASA Astrophysics Data System (ADS)

Interstitial laser thermotherapy is a minimally invasive surgical procedure that utilizes laser to coagulate and treat benign prostatic hyperplasia. This study explores the use of a computer-assisted interstitial laser coagulation system to aid surgeons in performing this procedure.

Ho, Gideon; Barrett, Adrian R. W.; Ng, Wan S.; Lim, Liam G.; Cheng, Wai S.

2001-06-01

399

Assessing blood coagulation status with laser speckle rheology  

PubMed Central

We have developed and investigated a novel optical approach, Laser Speckle Rheology (LSR), to evaluate a patient’s coagulation status by measuring the viscoelastic properties of blood during coagulation. In LSR, a blood sample is illuminated with laser light and temporal speckle intensity fluctuations are measured using a high-speed CMOS camera. During blood coagulation, changes in the viscoelastic properties of the clot restrict Brownian displacements of light scattering centers within the sample, altering the rate of speckle intensity fluctuations. As a result, blood coagulation status can be measured by relating the time scale of speckle intensity fluctuations with clinically relevant coagulation metrics including clotting time and fibrinogen content. Our results report a close correlation between coagulation metrics measured using LSR and conventional coagulation results of activated partial thromboplastin time, prothrombin time and functional fibrinogen levels, creating the unique opportunity to evaluate a patient’s coagulation status in real-time at the point of care. PMID:24688816

Tripathi, Markandey M.; Hajjarian, Zeinab; Van Cott, Elizabeth M.; Nadkarni, Seemantini K.

2014-01-01

400

Safety procedures of coagulation factors.  

PubMed

Two main types of safety procedures must be applied to biological products, including plasma derivatives: (i) preventive procedures and (ii) elimination procedures. Prevention includes epidemiological control of donor populations; checks on each donor's health condition; analysis of each donation for the main pathogens using serological methods; additional analysis of all plasma for human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis A virus (HAV) and the B19 virus, using nucleic acid amplification techniques (NAT). A 60 days or longer inventory hold of all plasma donations is applied, to allow additional time to discard previous donations from potential seroconverting or otherwise rejectable donors. Elimination procedures minimize the low residual risk of transmitting pathogens, including unknown or previously undetected ones. Since the introduction 20 years ago of solvent-detergent treatment, very effective against enveloped viruses (HIV, HBV, HCV, West Nile virus, SARS, avian influenza virus etc), there have been no known cases of transmission of this type of pathogens by products manufactured according to this procedure. Other inactivation procedures such as pasteurization, dry-heat or nanofiltration may prove equally effective. In addition, dry-heat treatment and nanofiltration are capable of effectively eliminating non-enveloped viruses (HAV, B19 virus). Recent studies show that the B19 virus is much more sensitive to heat (in lyophilized state or by pasteurization) and acid pH than previously thought. Although there is no evidence for the transmission of classic transmissible spongiform encephalopathies (TSEs) through blood or blood-products transfusion, four possible cases have been reported in the United Kingdom involving transmission by non-leukoreduced blood components of the agent that causes variant Creutzfeldt-Jakob Disease (vCJD), a disease linked to the outbreak of bovine spongiform encephalopathy (BSE) which took place in that country. However, there are no cases of human TSE (classic or variant) transmission by plasma-derived products. Analytical methods capable of detecting the vCJD agent in patients' brains (where high titres are found) and other tissues (such as the spleen, appendix and lymph nodes, where much lower concentrations are found) are unable to detect the agent in blood or plasma from patients with vCJD, even in the clinical phase of the disease. Experiments by Grifols and other groups show that the capacity of the production processes to eliminate vCJD agent models is many orders of magnitude greater than the maximum expected load of the agent. In this regard, the efficacy of precipitation, affinity chromatography, depth filtration and nanofiltration are particularly notable. PMID:18078396

Jorquera, J I

2007-12-01

401

Probe measurements in thermal plasma jets  

Microsoft Academic Search

Measurements of composition, temperature, and velocity in atmospheric argon plasma jets are reported, using enthalpy probes. The plasma jets are generated by a commercial type plasma gun and the measurements are expected to be of particular interest for industrial applications such as plasma spraying. Emphasis has been on the central and downstream regions of the plasma flame. The entrainment of

M. Brossa; E. Pfender

1988-01-01

402

Disseminated intravascular coagulation in patients with solid tumors.  

PubMed

Disseminated intravascular coagulation (DIC) is an occasional complication of solid tumors, usually identified at the time of presentation because of excessive bleeding, thromboembolic complications, or abnormal laboratory test results. The latter include an unexplained low platelet count, a low fibrinogen level, an elevated D-dimer level, and a prolonged prothrombin time. Prompt diagnosis and treatment of the underlying malignancy can result in resolution of the DIC. Further, if the tumor is responsive to chemotherapy, a reasonable median survival can also result. Excessive bleeding at presentation can be managed with platelet transfusions, cryoprecipitate, and fresh frozen plasma. Thromboembolic complications can be managed with continuous intravenous heparin and supportive platelet transfusions; cryoprecipitate can be used whenever necessary to support platelet and fibrinogen levels. On occasion, when excessive bleeding and venous thromboembolism occur together, placement of a vena cava filter is required, along with the administration of platelets and cryoprecipitate. PMID:25683828

Feinstein, Donald I

2015-02-01

403

A DSMC Study of Low Pressure Argon Discharge  

NASA Technical Reports Server (NTRS)

Work toward a self-consistent plasma simulation using the DSMC (Direct Simulation Monte Carlo) method for examination of the flowfields of low-pressure high density plasma reactors is presented. Presently, DSMC simulations for these applications involve either treating the electrons as a fluid or imposing experimentally determined values for the electron number density profile. In either approach, the electrons themselves are not physically simulated. Self-consistent plasma DSMC simulations have been conducted for aerospace applications but at a severe computational cost due in part to the scalar architectures on which the codes were employed. The present work attempts to conduct such simulations at a more reasonable cost using a plasma version of the object-oriented parallel Cornell DSMC code, MONACO, on an IBM SP-2. Due to availability of experimental data, the GEC reference cell is chosen to conduct preliminary investigations. An argon discharge is chosen to conduct preliminary investigations. An argon discharge is examined thus affording a simple chemistry set with eight gas-phase reactions and five species: Ar, Ar(+), Ar(*), Ar(sub 2), and e where Ar(*) is a metastable.

Hash, David B.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

1997-01-01

404

Effect of coagulants on the fouling and performance of ultrafiltration (UF) membranes  

Microsoft Academic Search

The combined coagulation and ultrafiltration (UF) system (C-UF system) is an advanced technology to treat natural organic matter (NOM) present in water. Traditional coagulants—prehydrolyzed inorganic coagulants, organic coagulants and composite coagulants were chosen to treat synthetic water containing humic acid (HA) in order to find an efficient coagulant that could remove NOM from the water effectively. The fouling, removal efficiency

Yan Wang; Xiuming Xu; V. Jegatheesan; Baoyu Gao

2009-01-01

405

RBF neural network predictive control for coagulant dosage  

Microsoft Academic Search

Coagulant control plays an important role in water treatment process. Considering the nonlinear and time-delaying property of coagulation, a model of coagulant dosage based on RBF neural network is developed. The Gaussian function is used for hidden note function, whose centers are adjusted by K-means clustering algorithm. The weights of output layer are obtained based on RLS. The model has

Li Wang

2004-01-01

406

Coagulation factor VII variants resistant to inhibitory antibodies.  

PubMed

Replacement therapy is currently used to prevent and treat bleeding episodes in coagulation factor deficiencies. However, structural differences between the endogenous and therapeutic proteins might increase the risk for immune complications. This study was aimed at identifying factor (F)VII variants resistant to inhibitory antibodies developed after treatment with recombinant activated factor VII (rFVIIa) in a FVII-deficient patient homozygous for the p.A354V-p.P464Hfs mutation, which predicts trace levels of an elongated FVII variant in plasma. We performed fluorescent bead-based binding, ELISA-based competition as well as fluorogenic functional (activated FX and thrombin generation) assays in plasma and with recombinant proteins. We found that antibodies displayed higher affinity for the active than for the zymogen FVII (half-maximal binding at 0.54 ± 0.04 and 0.78 ± 0.07 BU/ml, respectively), and inhibited the coagulation initiation phase with a second-order kinetics. Isotypic analysis showed a polyclonal response with a large predominance of IgG1. We hypothesised that structural differences in the carboxyl-terminus between the inherited FVII and the therapeutic molecules contributed to the immune response. Intriguingly, a naturally-occurring, poorly secreted and 5-residue truncated FVII (FVII-462X) escaped inhibition. Among a series of truncated rFVII molecules, we identified a well-secreted and catalytically competent variant (rFVII-464X) with reduced binding to antibodies (half-maximal binding at 0.198 ± 0.003 BU/ml) as compared to the rFVII-wt (0.032 ± 0.002 BU/ml), which led to a 40-time reduced inhibition in activated FX generation assays. Taken together our results provide a paradigmatic example of mutation-related inhibitory antibodies, strongly support the FVII carboxyl-terminus as their main target and identify inhibitor-resistant FVII variants. PMID:25104096

Branchini, Alessio; Baroni, Marcello; Pfeiffer, Caroline; Batorova, Angelika; Giansily-Blaizot, Muriel; Schved, Jean F; Mariani, Guglielmo; Bernardi, Francesco; Pinotti, Mirko

2014-11-01

407

The effect of estrogen replacement therapy with or without progestogen on the fibrinolytic system and coagulation inhibitors in postmenopausal status  

Microsoft Academic Search

OBJECTIVE: The aim of this study was to analyze several fibrinolytic components and coagulation inhibitors in postmenopausal women and to evaluate the effect of hormone replacement therapy.STUDY DESIGN: Several hemostatic parameters were evaluated in 75 postmenopausal women before and after 3 to 4 and 12 months of hormone therapy.RESULTS: An increase in plasma fibrinolytic activity primarily related to a significant

Juan Gilabert; Amparo Estellés; Antonio Cano; Francisco España; Rosa Barrachina; Salvador Grancha; Justo Aznar; Miguel Tortajada

1995-01-01

408

Alveolar rhabdomyosarcoma presenting as subacute intravascular coagulation.  

PubMed Central

A patient with rhabdomyosarcoma is described in whom the presenting clinical and laboratory features were those of disseminated intravascular coagulation. The patient's rapid downhill course was primarily expressed by haemorrhagic tendency. An alveolar rhabdomyosarcoma, affecting many organs, including vascular and cardiac lumina, was found at necropsy and was considered to be the cause of the consumption coagulopathy. Images PMID:886020

Eldor, A; Naparstek, E; Boss, J H; Biran, S

1977-01-01

409

Interaction between the coagulation and complement system.  

PubMed

The complement system as a main column of innate immunity and the coagulation system as a main column in hemostasis undergo massive activation early after injury. Interactions between the two cascades have often been proposed but the precise molecular pathways of this interplay are still in the dark. To elucidate the mechanisms involved, the effects of various coagulation factors on complement activation and generation of anaphylatoxins were investigated and summarized in the light of the latest literature. Own in vitro findings suggest, that the coagulation factors FXa, FXIa and plasmin may cleave both C5 and C3, and robustly generate C5a and C3a (as detected by immunoblotting and ELISA). The produced anaphylatoxins were found to be biologically active as shown by a dose-dependent chemotactic response of neutrophils and HMC-1 cells, respectively. Thrombin did not only cleave C5 (Huber-Lang et al. 2006) but also in vitro-generated C3a when incubated with native C3. The plasmin-induced cleavage activity could be dose-dependently blocked by the serine protease inhibitor aprotinin and leupeptine. These findings suggest that various serine proteases belonging to the coagulation system are able to activate the complement cascade independently of the established pathways. Moreover, functional C5a and C3a are generated, both of which are known to be crucially involved in the inflammatory response. PMID:19025115

Amara, Umme; Rittirsch, Daniel; Flierl, Michael; Bruckner, Uwe; Klos, Andreas; Gebhard, Florian; Lambris, John D; Huber-Lang, Markus

2008-01-01

410

Ophthalmic complications with disseminated intravascular coagulation  

Microsoft Academic Search

Massive lid oedema, ecchymosis, proptosis with a total restriction of extraocular movement, markedly raised intraocular pressure, and occlusion of the central retinal artery developed acutely in the right eye of a 26-year-old woman with a past history of disseminated intravascular coagulation. She had been admitted to hospital for symptoms of abdominal pain and bleeding from multiple sites a few hours

R. B. Patchett; W. B. Wilson; P. P. Ellis

1988-01-01

411

The rarer inherited coagulation disorders: A review  

Microsoft Academic Search

Of the inherited bleeding disorders, haemophilia A, haemophilia B and von Willebrand's disease make up together well over 80% of those registered with the UK Haemophilia Centre Directors. The common simple screening tests of coagulation may overlook some of the more rare disorders and it is clearly important that such uncommon bleeding disorders are excluded during the course of the

P. H. B. Bolton-Maggs; F. G. H. Hill

1995-01-01

412

Properties of argon-lithium discharges in a microwave resonant cavity  

SciTech Connect

A newly constructed microwave resonant cavity ion source will be used for laser-enhanced isotopic enrichment studies. The apparatus designed and tested in this work is smaller scale and uses an efficient microwave plasma ion source. This Asmussen-type source makes use of permanent rare-earth magnets to produce an electron cyclotron resonant region, making it more efficient for heating the plasma and allowing low pressure discharges to be maintained. A copper vapor laser pumped tunable dye laser will provide light for the excitation of the isotope to be enriched. The excited isotope will then be preferentially ionized and removed from the discharge chamber with a biased grid. In preparation for the isotopic enrichment studies, argon and argon-lithium discharges have been created and studied using well established plasma diagnostic techniques including Langmuir probe and optical emission spectroscopy. Plasma breakdown and operating conditions will be given for argon and argon-lithium discharges. Scalability of plasma parameters with input power, gas pressure and flow rate, and lithium concentration will be given. These results of preliminary studies will be shown along with an overview of the application for which the device is intended.

Brooks, C.B.; Brake, M.L.; Gilgenback, R.M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering

1994-12-31

413

Diamond electrodes modified by argon ion bombardment  

NASA Astrophysics Data System (ADS)

The electrochemical properties of boron-doped chemical vapour deposited diamond films following argon ion bombardment are investigated. The argon ion treatments used produce defects at the electrode surface, but are below the amorphisation threshold for this material, and indeed can be readily reversed by sample annealing. Photoemission studies indicate downwards band-bending of about 0.8 eV as a result of the argon ion treatment, and the photoemission spectra and associated energy loss spectra are used to examine the changes occurring. The higher argon ion exposures to the surface are found to very significantly degrade the electrochemical characteristics of diamond. However for smaller ion doses, the electrochemical properties of some redox couples are not influenced by the argon ion treatments used, whereas others are strongly inhibited. The work therefore demonstrates that argon ion bombardment can be used to selectively modify the properties of diamond electrodes.

Foord, John S.; Goeting, Christiaan H.

2004-09-01

414

Could light meal jeopardize laboratory coagulation tests?  

PubMed Central

Background: Presently the necessity of fasting time for coagulation tests is not standardized. Our hypothesis is that this can harm patient safety. This study is aimed at evaluating whether a light meal (i.e. breakfast) can jeopardize laboratory coagulation tests. Materials and methods: A blood sample was firstly collected from 17 fasting volunteers (12 h). Immediately after blood collection, the volunteers consumed a light meal. Then samples were collected at 1, 2 and 4 h after the meal. Coagulation tests included: activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen (Fbg), antithrombin III (AT), protein C (PC) and protein S (PS). Differences between samples were assessed by Wilcoxon ranked-pairs test. The level of statistical significance was set at P < 0.05. Mean % differences were determined and differences between and baseline and 1, 2 and 4h samples were compared with reference change value (RCV). Results: A significantly higher % activity of AT was observed at 1 h and 4 h after meal vs. baseline specimen [113 (104–117) and 111 (107–120) vs. 109 (102–118), respectively; P = 0.029 and P = 0.016]. APTT at 2 h was found significantly lower than baseline samples [32.0 (29.9–34.8) vs. 34.1 (32.2–35.2), respectively; P = 0.041]. The results of both Fbg and PS tests were not influenced by a light meal. Furthermore, no coagulation tests had significant variation after comparison with RCV. Conclusion: A light meal does not influence the laboratory coagulation tests we assessed, but we suggest that the laboratory quality managers standardize the fasting time for all blood tests at 12 hours, to completely metabolize the lipids intake. PMID:25351352

Lima-Oliveira, Gabriel; Salvagno, Gian Luca; Lippi, Giuseppe; Danese, Elisa; Gelati, Matteo; Montagnana, Martina; Picheth, Geraldo; Guidi, Gian Cesare

2014-01-01

415

Dusty plasmas  

SciTech Connect

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.

Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.

1996-05-01

416

Determining the electron temperature and the electron density by a simple collisional-radiative model of argon and xenon in low-pressure discharges  

NASA Astrophysics Data System (ADS)

A simple collisional-radiative model for argon and xenon is used, in conjunction with optical emission spectroscopy (line-ratio technique), to determine the electron temperature and electron density in low-pressure discharges containing argon and xenon. Satisfactory agreement is obtained between this method and the Langmuir probe for an inductively coupled plasma containing neon, argon and xenon. This method is applied for a capacitive discharge containing fluorocarbon, argon and xenon. The electron temperatures and electron densities obtained under various discharge conditions are compared with those reported in the literature by other techniques.

Zhu, Xi-Ming; Chen, Wen-Cong; Li, Jiang; Pu, Yi-Kang

2009-01-01

417

Effects Of Continuous Argon Laser Irradiation On Canine And Autopsied Human Cardiac Tissue  

NASA Astrophysics Data System (ADS)

In eight human formalin preserved cardiac specimens, various cardiac and vascular obstructions were relieved by argon laser irradiation. Interatrial communication was also produced by a transar'rial approach in a live dog. In-vivo fresh canine cardiac tissues required power density of at feast 80, 90, and 110 watts/cm2 for vaporization of myocardial, vascular and valvular tissues respectively. The fiber tip to tissue distance (effective irradiation distance) for effective vaporization was less than I mm for vascular and valvular tissues and less than 4 mm for myocardium. Light microscopy showed four zones of histological damage common to all tissues - central crater surrounded by layers of charring, vacuolization and coagulation necorsis. Myocardium showed additionally a layer of normal appearing muscle cells (skip area) surrounded by a peripheral coagulation halo. Laser irradiation effects on valvular tissue showed the most lateral extension of coagulation necrosis. It is concluded that palliation and treatment of certain congenital heart defects by laser irradiation is anatomi-cally feasible and may be safe for in vivo application when low power output and short exposure time are used from a very short irradiation distance.

Ben-Shachar, Giora; Sivakoff, Mark; Bernard, Steven L.; Dahms, Beverly B.; Riemenschneider, Thomas A.

1984-10-01

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

Effect of argon ion bombardment on amorphous silicon carbonitride films  

NASA Astrophysics Data System (ADS)

Amorphous silicon carbonitride (a-SiCN:H) films were synthesized by radiofrequency (RF) Plasma Enhanced Vapor Chemical Deposition (PECVD) using hexamethyldisilazane (HMDSN) as precursor compound. Then, the films were post-treated by Plasma Immersion Ion Implantation (PIII) in argon atmosphere from 15 to 60 min. The hardness of the film enhanced after ion implantation, and the sample treated at 45 min process showed hardness greater than sixfold that of the untreated sample. This result is explained by the crosslinking and densification of the structure. Films were exposed to oxygen plasma for determining of the etching rate. It decreased monotonically from 33 Å/min to 19 Å/min for the range of process time, confirming structural alterations. Hydrophobic character of the a-SiCN:H films were modified immediately after ion bombardment, due to incorporation of polar groups. However, the high wettability of the films acquired by the ion implantation was diminished after aging in air. Therefore, argon PIII made a-SiCN:H films mechanically more resistant and altered their hydrophobic character.

Batocki, R. G. S.; Mota, R. P.; Honda, R. Y.; Santos, D. C. R.

2014-04-01

420

Fast and interrupted expansion in cyclic void growth in dusty plasma  

NASA Astrophysics Data System (ADS)

Low-pressure acetylene plasmas are able to spontaneously form dust particles. This will result in a dense cloud of solid particles that is levitated in the plasma. The formed particles can grow up to micrometers. We observed a spontaneous interruption in the expansion of the so-called dust void. A dust void is a macroscopic region in the plasma that is free of nanoparticles. The phenomenon is periodical and reproducible. We refer to the expansion interruption as ‘hiccup’. The expanding void is an environment in which a new cycle of dust particle formation can start. At a certain moment in time, this cycle reaches the (sudden) coagulation phase and as a result the void will temporarily shrink. To substantiate this reasoning, the electron density is determined non-intrusively using microwave cavity resonance spectroscopy. Moreover, video imaging of laser light scattering of the dust particles provides their spatial distribution. The emission intensity of a single argon transition is measured similarly. Our results support the aforementioned hypothesis for what happens during the void hiccup. The void dynamics preceding the hiccup are modeled using a simple analytical model for the two dominant forces (ion drag and electric) working on a nanoparticle in a plasma. The model results qualitatively reproduce the measurements.

van de Wetering, F. M. J. H.; Brooimans, R. J. C.; Nijdam, S.; Beckers, J.; Kroesen, G. M. W.

2015-01-01

421

The coagulation characteristics of humic acid by using acid-soluble chitosan, water-soluble chitosan, and chitosan coagulant mixtures.  

PubMed

Chitosan is a potential substitute for traditional aluminium salts in water treatment systems. This study compared the characteristics of humic acid (HA) removal by using acid-soluble chitosan, water-soluble chitosan, and coagulant mixtures of chitosan with aluminium sulphate (alum) or polyaluminium chloride (PACl). In addition, we evaluated their respective coagulation efficiencies at various coagulant concentrations, pH values, turbidities, and hardness levels. Furthermore, we determined the size and settling velocity of flocs formed by these coagulants to identify the major factors affecting HA coagulation. The coagulation efficiency of acid- and water-soluble chitosan for 15?mg/l of HA was 74.4% and 87.5%, respectively. The optimal coagulation range of water-soluble chitosan (9-20?mg/l) was broader than that of acid-soluble chitosan (4-8?mg/l). Notably, acid-soluble chitosan/PACl and water-soluble chitosan/alum coagulant mixtures exhibited a higher coagulation efficiency for HA than for PACl or alum alone. Furthermore, these coagulant mixtures yielded an acceptable floc settling velocity and savings in both installation and operational expenses. Based on these results, we confidently assert that coagulant mixtures with a 1:1 mass ratio of acid-soluble chitosan/PACl and water-soluble chitosan/alum provide a substantially more cost-effective alternative to using chitosan alone for removing HA from water. PMID:25362971

Chen, Chih-Yu; Wu, Chung-Yu; Chung, Ying-Chien

2015-05-01

422

21 CFR 868.1075 - Argon gas analyzer.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Argon gas analyzer. 868.1075 Section 868...DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to...

2013-04-01

423

21 CFR 868.1075 - Argon gas analyzer.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 2014-04-01 false Argon gas analyzer. 868.1075 Section 868...DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to...

2014-04-01

424

21 CFR 868.1075 - Argon gas analyzer.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 2012-04-01 false Argon gas analyzer. 868.1075 Section 868...DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to...

2012-04-01

425

21 CFR 868.1075 - Argon gas analyzer.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 false Argon gas analyzer. 868.1075 Section 868...DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to...

2011-04-01

426

CERN, 23 October 2001 A prototype magnetized liquid Argon detector  

E-print Network

CERN, 23 October 2001 µ-LANNDD A prototype magnetized liquid Argon detector for electron charge Abstract A liquid Argon TPC detector immersed in magnetic field is proposed for systematic study...................................................................................................................................10 3. The liquid Argon TPC

McDonald, Kirk

427

Numerical Study of a Free-Burning Argon Arc with Anode Melting  

Microsoft Academic Search

Numerical modeling of free burning arcs and their electrodes is useful for clarifying the heat transfer phenomena in the welding process and to elucidate those effects which determine the weld penetration. This paper presents predictions for a stationary welding process by the free-burning argon arc. The whole region of the welding process, namely, tungsten cathode, arc plasma and stainless steel

Manabu Tanaka; Hidenori Terasaki; Masao Ushio; John J. Lowke

2003-01-01

428

Observation of ? mode electron heating in dusty argon radio frequency discharges  

SciTech Connect

The time-resolved emission of argon atoms in a dusty plasma has been measured with phase-resolved optical emission spectroscopy using an intensified charge-coupled device camera. For that purpose, three-dimensional dust clouds have been confined in a capacitively coupled rf argon discharge with the help of thermophoretic levitation. While electrons are exclusively heated by the expanding sheath (? mode) in the dust-free case, electron heating takes place in the entire plasma bulk when the discharge volume is filled with dust particles. Such a behavior is known as ? mode, first observed in electronegative plasmas. Furthermore, particle-in-cell simulations have been carried out, which reproduce the trends of the experimental findings. These simulations support previous numerical models showing that the enhanced atomic emission in the plasma can be attributed to a bulk electric field, which is mainly caused by the reduced electrical conductivity due to electron depletion.

Killer, Carsten; Bandelow, Gunnar; Schneider, Ralf; Melzer, André [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)] [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany); Matyash, Konstantin [Universitätsrechenzentrum, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)] [Universitätsrechenzentrum, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)

2013-08-15

429

Liquid argon calorimetry for the SSC  

SciTech Connect

Liquid argon calorimetry is a mature technique. However, adapting it to the challenging environment of the SSC requires a large amount of R D. The advantages of the liquid argon approach are summarized and the issues being addressed by the R D program are described. 18 refs.

Gordon, H.A.

1990-01-01

430

Cryogenic air separation with cold argon recycle  

Microsoft Academic Search

The invention provides an efficient means of increasing oxygen purity and recovery and also argon recovery in cryogenic distillative air separation plants. In addition, the invention makes it possible to increase the oxygen delivery pressure from high efficiency triple pressure configurations without using an oxygen vacuum compressor. These advantages are obtained by incorporating an argon recycle compressor within the cold

Erickerson

1985-01-01

431

Nonequilibrium structure of argon shock waves  

Microsoft Academic Search

This theoretical study investigates the influence of (1) the nonequilibrium excited state population in the relaxation region and (2) line radiation in the precursor on shock wave structure by considering strong shock waves propagating at Mach 18 and 24 into a theoretical argon-like gas at a pressure of 1 cm Hg and a temperature of 300 °K. The argon atom

H. F. Nelson

1973-01-01

432

Insulin resistance syndrome: interaction with coagulation and fibrinolysis.  

PubMed

Insulin resistance represents a common metabolic abnormality leading to cardiovascular disease, the major cause of morbidity and mortality in most parts of the world. Insulin resistance is also associated with an increased risk of type 2 diabetes which is strongly associated with obesity. The insulin resistance of obese people and subjects with type 2 diabetes is characterised by defects at many levels, affecting insulin receptor concentration, glucose transport mechanisms and the activities of intracellular enzymes. Around 25% of western populations show some features of the insulin resistance syndrome (often referred to as syndrome X or the metabolic syndrome) ie, a clustering of metabolic, atheromatous risk factors, including hypertriglyceridaemia, hyperinsulinaemia, hyper-tension, hypercholesterinaemia and obesity. However, the known metabolic cardiovascular risk factors associated with the insulin resistance syndrome do not sufficiently explain the excess vascular risk attributed to this syndrome. The observation, that increased plasma plasminogen activator inhibitor 1 (PAI-1) levels were associated with insulin resistance and atherothrombosis added for the first time a pathological basis for an association of the insulin resistance syndrome not only with metabolic, atheromatous (atherosclerotic) risk but also with atherothrombotic risk. It is very likely that not only PAI-1, but also other abnormalities in haemostatic variables contribute to this excess vascular risk. Knowledge of how haemostatic variables cluster with classical metabolic risk factors associated with the insulin resistance syndrome could help to better understand the pathogenesis of cardiovascular diseases. Indeed, many coagulation and fibrinolytic proteins have been shown to be associated with features of the insulin resistance syndrome and these associations suggest that some coagulation and fibrinolytic proteins have a role in atherothrombotic disorders, principally through an association with other established metabolic (atheromatous) risk factors in the presence of underlying insulin resistance. Interestingly, new therapeutic approaches in the prevention and treatment of insulin resistance do show some influence on coagulation and fibrinolysis. The newest drugs are the thiazolidinediones, a totally novel class of insulin sensitisers. They have the potential to offer improvements both in glycaemic control and in cardiovascular events. PMID:12148078

Kohler, Hans-Peter

2002-05-18

433

Arsenic removal from drinking water during coagulation  

Microsoft Academic Search

The efficiency of arsenic removal from source waters and artificial freshwaters during coagulation with ferric chloride and alum was examined in bench-scale studies. Arsenic(V) removal by either ferric chloride or alum was relatively insensitive to variations in source water composition below pH 8. At pH 8 and 9, the efficiency of arsenic(V) removal by ferric chloride was decreased in the

Janet G. Hering; Pen-Yuan Chen; Jennifer A. Wilkie; Menachem Elimelech

1997-01-01

434

Patterned retinal coagulation with a scanning laser  

NASA Astrophysics Data System (ADS)

Pan-retinal photocoagulation in patients with diabetic retinopathy typically involves application of more than 1000 laser spots; often resulting in physician fatigue and patient discomfort. We present a semi-automated patterned scanning laser photocoagulator that rapidly applies predetermined patterns of lesions; thus, greatly improving the comfort, efficiency and precision of the treatment. Patterns selected from a graphical user interface are displayed on the retina with an aiming beam, and treatment can be initiated and interrupted by depressing a foot pedal. To deliver a significant number of burns during the eye's fixation time, each pulse should be considerably shorter than conventional 100ms pulse duration. We measured coagulation thresholds and studied clinical and histological outcomes of the application of laser pulses in the range of 1-200ms in pigmented rabbits. Laser power required for producing ophthalmoscopically visible lesions with a laser spot of 132?m decreased from 360 to 37mW with pulse durations increasing from 1 to 100ms. In the range of 10-100ms clinically and histologically equivalent light burns could be produced. The safe therapeutic range of coagulation (ratio of the laser power required to produce a rupture to that for a light burn) decreased with decreasing pulse duration: from 3.8 at 100ms, to 3.0 at 20ms, to 2.5 at 10ms, and to 1.1 at 1ms. Histology demonstrated increased confinement of the thermal damage with shorter pulses, with coagulation zone limited to the photoreceptor layer at pulses shorter than 10ms. Durations of 10-20ms appear to be a good compromise between the speed and safety of retinal coagulation. Rapid application of multiple lesions greatly improves the speed, precision, and reduces pain in retinal photocoagulation.