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1

Application of Argon Plasma Coagulation in Skin Surgery  

Microsoft Academic Search

Background: Argon plasma coagulation (APC) is a noncontact electrosurgical technique which has been used in open surgery for about 20 years and in endoscopy for about 5 years. Objective: The aim of the present study was to provide preliminary results on the effect of this method in skin surgery. Methods: The effects of variations in gas flow, output power and

C. U. Brand; A. Blum; A. Schlegel; G. Farin; C. Garbe

1998-01-01

2

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.

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

2014-01-01

3

Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator  

Microsoft Academic Search

Background  Distal migration is one of the common complications after insertion of a covered metallic stent. Stent repositioning or removal\\u000a is not always possible in every patient. Therefore, trimming using an argon plasma coagulator (APC) may be a good alternative\\u000a method to solve this problem.\\u000a \\u000a \\u000a \\u000a Methods  Metallic stent trimming by APC was performed in 2 patients with biliary Wallstent migration and in

Rungsun Rerknimitr; Pisit Naprasert; Pradermchai Kongkam; Pinit Kullavanijaya

2007-01-01

4

Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator  

SciTech Connect

Background. Distal migration is one of the common complications after insertion of a covered metallic stent. Stent repositioning or removal is not always possible in every patient. Therefore, trimming using an argon plasma coagulator (APC) may be a good alternative method to solve this problem. Methods. Metallic stent trimming by APC was performed in 2 patients with biliary Wallstent migration and in another patient with esophageal Ultraflex stent migration. The power setting was 60-100 watts with an argon flow of 0.8 l/min. Observations. The procedure was successfully performed and all distal parts of the stents were removed. No significant collateral damage to the nearby mucosa was observed. Conclusions. In a patient with a distally migrated metallic stent, trimming of the stent is possible by means of an APC. This new method may be applicable to other sites of metallic stent migration.

Rerknimitr, Rungsun, E-mail: Rungsun@pol.net; Naprasert, Pisit; Kongkam, Pradermchai; Kullavanijaya, Pinit [Faculty of Medicine, Chulalongkorn University, Gastroenterology Unit, Department of Internal Medicine (Thailand)

2007-06-15

5

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

PubMed Central

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

Chanis, Ricardo; Khoshoo, Vikram

2012-01-01

6

Argon plasma coagulation of hemorrhagic solitary rectal ulcer syndrome.  

PubMed

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

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

2003-01-01

7

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.

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

2012-01-01

8

The efficacy and safety of argon plasma coagulation therapy in Barrett's esophagus  

Microsoft Academic Search

Background: Thermoablation is being used to eliminate the metaplastic epithelium of Barrett's esophagus and allow its reversal into squamous epithelium in an acid-controlled environment. This study assessed the efficacy and safety of a new thermoablation technique, argon plasma coagulation. Methods: Patients with circumferential Barrett's esophagus 2 to 5 cm long were enrolled. Acid suppression was accomplished with lansoprazole. One-half the

Andrew J. Grade; Ifat A. Shah; Susan M. Medlin; Francisco C. Ramirez

1999-01-01

9

Argon plasma coagulation, bipolar cautery, and cryotherapy: ABC's of ablative techniques.  

PubMed

A variety of endoscopic ablation modalities are available for the treatment of Barrett's esophagus. Multiple studies have evaluated the use of argon plasma coagulation, mostly in nondysplastic Barrett's esophagus. Significant variations in technique, end points, and follow-up exist between studies, but in most cases argon plasma coagulation is associated with unacceptable rates of persistent intestinal metaplasia and recurrence after completion of treatment. In addition, serious adverse events including perforation and stricture formation are reported. Multipolar electrocoagulation has been studied less thoroughly, but in prospective trials significant rates of persistent and recurrent intestinal metaplasia have also been reported. Lasers and heater probes have been tried in small numbers. Endoscopic cryotherapy ablation is a relatively new technique with studies focusing on high-grade dysplasia and early-stage cancer in high-risk patients. It has an acceptable safety profile, and early results show response in a significant number of patients in whom other modalities have failed. PMID:19065487

Dumot, J A; Greenwald, B D

2008-12-01

10

Endoscopic removal of a migrating polyester band using argon plasma coagulation.  

PubMed

A case is reported of a 40-year-old woman with a past history of bariatric surgery with vertical banding gastroplasty. Migrating band was observed during upper GI endoscopy performed for pyrosis. Before undergoing another bariatric intervention, migrated band had to be removed. This procedure was successfully performed endoscopically using argon plasma coagulation. No complication occurred. This case highlights that migrated band could be easily and safely removed without the need of specific or dedicated endoscopic tool. PMID:23273494

Musquer, Nicolas; Letessier, Eric; Le Rhun, Marc; Coron, Emmanuel

2013-06-01

11

Pneumoretroperitoneum and pneumoperitoneum following argon plasma coagulation for a bleeding duodenal diverticulum: a case report.  

PubMed

Duodenal diverticula are usually asymptomatic, with an incidence of 0.16% to 22%. Symptomatic bleeding from a duodenal diverticulum is an even rarer event. The management of such a hemorrhage is almost entirely surgically based. Since the first reported case of endoscopic therapy for duodenal diverticular bleeding (DDB) by Sim et al, only two case series have been reported in the literature regarding endoscopic therapy for DDB. Hence, the optimal therapy modality for DDB remains unclear. A rare case involving massive pneumoretroperitoneum and pneumoperitoneum following argon plasma coagulation treatment for DDB is presented. A short discussion of the optimal endoscopic therapy for this rare disease is provided. PMID:20065903

Su, Pei-Yuan; Yen, Hsu-Heng

2010-02-01

12

Epinephrine plus argon plasma or heater probe coagulation in ulcer bleeding  

PubMed Central

AIM: To compare the effectiveness of argon plasma coagulation (APC) and heater probe coagulation (HPC) in non-variceal upper gastrointestinal bleeding. METHODS: Eighty-five (18 female, 67 male) patients admitted for acute gastrointestinal bleeding due to gastric or duodenal ulcer were included in the study. Upper endoscopy was performed and HPC or APC were chosen randomly to stop the bleeding. Initial hemostasis and rebleeding rates were primary and secondary end-points of the study. RESULTS: Initial hemostasis was achieved in 97.7% (42/43) and 81% (36/42) of the APC and HPC groups, respectively (P < 0.05). Rebleeding rates were 2.4% (1/42) and 8.3% (3/36) in the APC and HPC groups, respectively, at 4 wk (P > 0.05). CONCLUSION: APC is an effective hemostatic method in bleeding peptic ulcers. Larger multicenter trials are necessary to confirm these results.

Karaman, Ahmet; Baskol, Mevlut; Gursoy, Sebnem; Torun, Edip; Yurci, Alper; Ozel, Banu Demet; Guven, Kadri; Ozbakir, Omer; Yucesoy, Mehmet

2011-01-01

13

Safety of argon plasma coagulation for hemostasis during endoscopic mucosal resection.  

PubMed

Showing the safety of argon plasma coagulation (APC) over mucosal defects during/after endoscopic mucosal resection (EMR), 2 studies using resected pig (ex vivo) and living minipig (in vivo) stomachs were performed. As an ex vivo study, APC was applied over mucosal defects in 2 groups; with prior submucosal saline injection and without injection. Only subtle tissue damage was observed in the injection group, whereas apparent damage was observed in the noninjection group. The damaged distances in depth significantly increased as the pulse duration increased and those at the pulse duration of 4 seconds, which might be maximal in clinical practice, were approximately 1 mm. As an in vivo study, APC was applied over mucosal defects immediately after EMR. Only subtle tissue damage was observed even at the pulse duration of 20 seconds as shown in the ex vivo study. APC can be performed safely over the mucosal defects during/after EMR. PMID:16804454

Fujishiro, Mitsuhiro; Yahagi, Naohisa; Nakamura, Masanori; Kakushima, Naomi; Kodashima, Shinya; Ono, Satoshi; Kobayashi, Katsuya; Hashimoto, Takuhei; Yamamichi, Nobutake; Tateishi, Ayako; Shimizu, Yasuhito; Oka, Masashi; Ichinose, Masao; Omata, Masao

2006-06-01

14

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

15

Bronchial asthma control after argon plasma coagulation turbinectomy in patients with chronic rhinitis.  

PubMed

Bronchial asthma is frequently accompanied by chronic rhinitis. It has been observed that effective treatment of rhinitis may reduce asthma symptoms. The aim of the study was the evaluation of the control of bronchial asthma symptoms in patients with chronic rhinitis after argon plasma coagulation turbinectomy (APCt). The effect of APCt was assessed in 47 adults with drug-resistant chronic rhinitis and bronchial asthma 3-month post-procedure. Changes of asthma symptoms were scored using Asthma Control Test (ACT). Subjective improvement of nasal congestion 3 months after APCt was observed in 87 % and of rhinorrhoea in 75 % patients. Rhinomanometry showed 219 ± 19 cm³/s increase of flow and 0.75 ± 0.06 Pa/cm³/s reduction of resistance. The prevalence of patients with insufficient bronchial asthma control decreased from 79 to 4 %. The decrease was associated with diminished frequency of eosinophils >20 % in nasal cytology from 83 % pre-procedure to 28 % in the follow-up. The percentage of eosinophils >20 % in cytology before APCt increased the chance for asthma control improvement by 22.8 times. Reduction in symptoms of drug-resistant rhinitis after APCt is followed by significant improvement of asthma control. The most beneficial therapeutic effects of APCt are noted in patients with a high rate of eosinophils in nasal cytology. PMID:24141470

Jura-Szo?tys, Edyta; Ficek, Rafa?; Ficek, Joanna; Markowski, Jaros?aw; Chudek, Jerzy

2014-06-01

16

Argon plasma coagulation with submucosal saline injection for gastric adenoma on outpatient basis.  

PubMed

Gastric adenoma with low-grade dysplasia (LGD) is a less progressive disease than with high-grade dysplasia; nevertheless, a certain portion of lesions can progress. The purpose of this study was to evaluate the effectiveness of argon plasma coagulation (APC) with submucosa saline injections (APC-SSI) for gastric adenoma with LGD on an outpatient department (OPD) basis. We included 57 patients with 64 lesions of gastric adenoma with LGD. Endoscopic type was flat elevated in 58 lesions and central depressed in 6 lesions. Normal saline was injected into the submucosa under the lesion before APC. APC was performed to the lesion and its surrounding mucosa. After treatment, patients underwent regular endoscopy follow-ups. One case each of pneumoperitoneum and Mallory-Weiss tearing occurred and could be managed with conservative care. One case of overt bleeding occurred after 2 weeks and was treated with APC. After 19.5 months of follow-up, four residual adenomas (6.3%) were found and treated with additional APC-SSI. Fourteen metachronous lesions were noted in eight patients (14.0%). Twelve lesions were adenoma with LGD and two lesions were intramucosal adenocarcinoma. APC-SSI is an effective and safe treatment modality for gastric adenoma with LGD on an OPD basis and it is recommended for patients with risk factors of endoscopic mucosal resection (EMR). After treatment of gastric adenoma, meticulous follow-up endoscopy is recommended for detection of metachronous lesions. PMID:19082886

Lee, Kee Myung; Kim, Young Bae; Sin, Sung Jae; Jung, Jae Yeon; Hwang, Jae Chul; Lim, Sun Gyo; Yoo, Byung Moo; Kim, Jin Hong; Cho, Sung Won

2009-12-01

17

Argon plasma coagulation for superficial esophageal squamous-cell carcinoma in high-risk patients  

PubMed Central

AIM: To evaluate the usefulness and safety of argon plasma coagulation (APC) for superficial esophageal squamous-cell carcinoma (SESC) in high-risk patients. METHODS: We studied 17 patients (15 men and 2 women, 21 lesions) with SESC in whom endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), and open surgery were contraindicated from March 1999 through February 2009. None of the patients could tolerate prolonged EMR/ESD or open surgery because of severe concomitant disease (e.g., liver cirrhosis, cerebral infarction, or ischemic heart disease) or scar formation after EMR/ESD and chemoradiotherapy. After conventional endoscopy, an iodine stain was sprayed on the esophageal mucosa to determine the lesion margins. The lesion was then ablated by APC. We retrospectively studied the treatment time, number of APC sessions per site, complications, presence or absence of recurrence, and time to recurrence. RESULTS: The median duration of follow-up was 36 mo (range: 6-120 mo). All of the tumors were macroscopically classified as superficial and slightly depressed type (0-IIc). The preoperative depth of invasion was clinical T1a (mucosal cancer) for 19 lesions and clinical T1b (submucosal cancer) for 2. The median treatment time was 15 min (range: 10-36 min). The median number of treatment sessions per site was 2 (range: 1-4). The median hospital stay was 14 d (range: 5-68 d). Among the 17 patients (21 lesions), 2 (9.5%) had recurrence and underwent additional APC with no subsequent evidence of recurrence. There were no treatment-related complications, such as bleeding or perforation. CONCLUSION: APC is considered to be safe and effective for the management of SESC that cannot be resected endoscopically because of underlying disease, as well as for the control of recurrence after EMR and local recurrence after chemoradiotherapy.

Tahara, Kumiko; Tanabe, Satoshi; Ishido, Kenji; Higuchi, Katsuhiko; Sasaki, Tohru; Katada, Chikatoshi; Azuma, Mizutomo; Nakatani, Kento; Naruke, Akira; Kim, Myungchul; Koizumi, Wasaburo

2012-01-01

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

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

PubMed Central

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

2012-01-01

20

Submucosal injection of normal saline may prevent tissue damage from argon plasma coagulation: an experimental study using resected porcine esophagus, stomach, and colon.  

PubMed

Argon plasma coagulation (APC) is considered to be a safe thermocoagulation technique, but some reports show perforation and deformity during and after APC. In this study, we investigated the usefulness of prior submucosal injection for APC. APC over the mucosa was performed on fresh resected porcine esophagus, stomach, and colon with prior submucosal injection of normal saline (injection group) and without it (control group). The depth of tissue damage increased linearly with pulse duration up to the shallower submucosal layer in both groups. After that, tissue damage in the injection group remained confined to the shallower submucosal layer under any condition, whereas that in the control group continued to extend. The tissue damages of the injection groups were significantly (P<0.05) shallower than those of the control groups that reached the deeper submucosal layer in all the organs. Submucosal injection of normal saline before the application of APC may limit tissue damage and prevent perforation and deformity. PMID:17057569

Fujishiro, Mitsuhiro; Yahagi, Naohisa; Nakamura, Masanori; Kakushima, Naomi; Kodashima, Shinya; Ono, Satoshi; Kobayashi, Katsuya; Hashimoto, Takuhei; Yamamichi, Nobutake; Tateishi, Ayako; Shimizu, Yasuhito; Oka, Masashi; Ichinose, Masao; Omata, Masao

2006-10-01

21

Argon beam coagulation in foot and ankle surgery.  

PubMed

In this brief report, we introduce the principles, indications, advantages, disadvantages, and surgical techniques involved in the use of argon beam coagulation in foot and ankle surgery. PMID:21907597

Adams, Melissa L; Steinberg, John S

2011-01-01

22

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

PubMed Central

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

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

2009-01-01

23

Argon plasma coagulation in Barrett's esophagus.  

PubMed

Despite the availability of many clinical trials, there is no evidence that APC has any role in the management of Barrett's esophagus. Ablation therapy is not indicated for nondysplastic Barrett's esophagus (and this is true, whatever the technique used), and it should not be performed outside of a carefully designed and approved clinical trial. Indeed, these patients have a low risk of cancer, and there is no evidence that Barrett's esophagus ablation will be of any benefit for these patients. In some cases, APC could be of some help, especially for treating short segments of dysplastic Barrett's esophagus. In this field, however, it competes with the growing indication of mucosectomy, which clearly offers advantages in terms of treatment's quality control assessment. PMID:14629102

Franchimont, Denis; Van Laethem, Jean-Luc; Devière, Jacques

2003-07-01

24

Non-LTE Argon-plasma Composition  

Microsoft Academic Search

In this paper theory of calculation of non-LTE plasma composition is presented. The calculations are conducted for argon plasma for temperature ranges from 500 K to 30, 000 K and Te\\/Th ratios from 1 to 10. The effect of different versions of the Saha equation, Debye length, lowering of ionisation energy and pressure correction on the argon-plasma composition is evaluated.

Andrew Piotrowski

2005-01-01

25

Thoracoscopic parietal pleural argon beam coagulation versus pleural abrasion in the treatment of primary spontaneous pneumothorax  

Microsoft Academic Search

Objective: The obliteration of pleural space is useful to prevent recurrences of spontaneous pneumothorax. We retrospectively compared the results of pleural argon beam coagulation versus pleural abrasion in the treatment of primary spontaneous pneumothorax. Methods: Between 1996 and 2004, 136 patients underwent surgery for primary spontaneous pneumothorax, with 143 surgical procedures, all performed by VATS. Indications were recurrent pneumothorax in

Antonio Bobbio; Luca Ampollini; Eveline Internullo; Domenico Caporale; Leonardo Cattelani; Stefano Bettati; Paolo Carbognani; Michele Rusca

2006-01-01

26

Thoracoscopic parietal pleural argon beam coagulation versus pleural abrasion in the treatment of primary spontaneous pneumothorax  

Microsoft Academic Search

Objective: The obliteration of pleural space is useful to prevent recurrences of spontaneous pneumothorax. We retrospectively compared the results of pleural argon beam coagulation versus pleural abrasion in the treatment of primary spontaneous pneumothorax. Methods: Between 1996 and 2004, 136 patients underwent surgery for primary spontaneous pneumothorax, with 143 surgical procedures, all performed by VATS. Indications were recurrent pneumothorax in

Antonio Bobbio; Luca Ampollini; Eveline Internullo; Domenico Caporale; Leonardo Cattelani; Stefano Bettati; Paolo Carbognani; Michele Rusca; Viale Gramsci

2010-01-01

27

Modelling of RF Discharge in Argon Plasma  

NASA Astrophysics Data System (ADS)

An one-dimensional hybrid model of RF discharge in low-temperature argon plasma is presented in our paper. The hybrid model consists of two parts-particle model which simulates fast electrons while fluid model simulates slow electrons and positive argon ions. In the particle model the positions and velocities of fast electrons are calculated by means of deterministic Verlet algorithm while the collision processes are treated by the stochastic way. For the solution of fluid equations, for slow electrons and positive argon ions, the Scharfetter-Gummel exponential algorithm was used. Typical results of our calculations presented in this paper are total RF current and RF voltage waveforms on the planar substrate immersed into argon plasma. The next results which can be found here are the ion, electron and displacement current waveforms on the substrate. Especially, the knowledge of waveform of the ion current is very important for experimental physicists during the deposition of thin films.

Jelínek, P.; Virostko, P.; Hubicka, Z.; Bartoš, P.

2007-12-01

28

Merging of High Speed Argon Plasma Jets  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

29

Merging of high speed argon plasma jets  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

30

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

PubMed

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

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

2003-10-01

31

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

32

Use of neutral plasma coagulation in groin node dissection for vulvar malignancy: a novel technique  

PubMed Central

Vulvar cancer is an uncommon disease with approximately 1000 cases reported annually in the UK. Lymph node involvement is an important prognostic indicator. Vulvectomy and bilateral groin node dissection are the preferred surgical treatments for early disease and increase survival. However, significant morbidity with lymphocyst formation and wound breakdown has been reported in more than 50% of cases. We report the first case following use of the PlasmaJet® neutral argon coagulation system to reduce postoperative lymphocyst formation.

Madhuri, Thumuluru Kavitha; Tailor, Anil; Butler-Manuel, Simon

2011-01-01

33

Contact Activation of Blood Plasma Coagulation  

PubMed Central

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

Vogler, Erwin A.; Siedlecki, Christopher A.

2009-01-01

34

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

35

Behavior of Excited Argon Atoms in Inductively Driven Plasmas  

Microsoft Academic Search

Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1sâ and 1sâ, 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 1sâ level is metastable and the 1sâ level is radiatively coupled to

GREGORY A. HEBNER; PAUL A. MILLER

1999-01-01

36

Turbulence and Transport in a Magnetized Argon Plasma.  

National Technical Information Service (NTIS)

An experimental study on turbulence and transport in the highly ionized argon plasma of a hollow cathode discharge is described. In order to determine the plasma parameters three standard diagnostics have been used, whilst two diagnostics have been develo...

B. F. M. Pots

1979-01-01

37

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

PubMed

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

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

2002-01-01

38

Study of a Plasma of Argon and Argonhydrogen Mixture.  

National Technical Information Service (NTIS)

In thhis report the relattive importances of elastic, inelastic, e-i and e-e collisions are investigated for plasmas of Argon and Argon-Hydrogen mixture. A differential equation neglecting propagation effect, is given, allowing to calculate the conductivi...

A. Constantin J. Godart JJ. J. Hamm R. Riioux

1964-01-01

39

Electron-Heavy Particle Nonequilibrium in a Dense Argon Plasma.  

National Technical Information Service (NTIS)

A theoretical and experimental study of the degree of electron heavy particle thermal nonequilibrium was conducted for a subsonic argon arcjet plasma at one atmosphere. A criterion for 'electron-temperature freezing' was calculated, and indicated that alt...

P. F. Jacobs J. Grey

1966-01-01

40

Argon plasma endoscopic section of biliary metallic prostheses.  

PubMed

We report our recent experience of using argon plasma to endoscopically cut biliary Wallstent prostheses in these patients. The first patient had a bleeding duodenal ulceration caused by the impaction of the prosthesis meshes whereas the second patient had an ill-positioned biliary stent with impaction into the opposite duodenal wall. Both prostheses were shortened using argon plasma. In the third patient, the lower extremity of a obstructed biliary Wallstent was positioned in the third duodenum preventing its endoscopic catheterization. After shortening using argon plasma, a new plastic stent could be inserted to allow drainage. The outcomes in these cases demonstrate the feasibility of endoscopically shortening metallic Wallstents after release using argon plasma. PMID:11293767

Demarquay, J F; Dumas, R; Peten, E P; Rampal, P

2001-03-01

41

Behavior of excited argon atoms in inductively driven plasmas  

Microsoft Academic Search

Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s5 and 1s4, 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 1s5 level is metastable and the 1s4 level is radiatively coupled to

G. A. Hebner; P. A. Miller

2000-01-01

42

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

43

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

44

Isotope fractionation in lithium plasma produced by argon contact ionization  

Microsoft Academic Search

The plasma isotope separation by the use of the secondary contact ionization ion source was studied. The electromagnetic wave tuned with the cyclotron frequency of lithium-7 ion was applied to the lithium-argon mixture plasma. The lithium deposited on the collector was measured by a mass spectrometer. It was confirmed that the isotope ratio of the sample taken after ICR heating

T Suzuki; M Nomura; M Okamoto; Y Fujii

1996-01-01

45

Effects of surrounding gas on the long laminar argon plasma jet characteristics  

Microsoft Academic Search

Comparative study is performed concerning the characteristics of long laminar argon plasma jets issuing into argon or into air surroundings. It is shown that when argon, instead of air, is used as the surrounding gas, besides pure argon atmosphere can be formed, the mass flow rate of surrounding gas entrained into the plasma jet and the length of jet high-temperature

Dong-Yan Xu; Xi Chen

2005-01-01

46

High time resolution laser induced fluorescence in pulsed argon plasma  

SciTech Connect

A submillisecond time resolution laser induced fluorescence (LIF) method for obtaining the temporal evolution of the ion velocity distribution function in pulsed argon plasma is presented. A basic LIF system that employs a continuous laser wave pumping and lock-in aided detection of the subsequent fluorescence radiation is modified by addition of a high frequency acousto-optic modulator to provide measurements of the ion flow velocity and ion temperature in a helicon generated pulsed argon plasma with temporal resolutions as high as 30 {mu}s.

Biloiu, Ioana A.; Sun Xuan; Scime, Earl E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

2006-10-15

47

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

National Technical Information Service (NTIS)

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

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

2002-01-01

48

Trimming of a Migrated Biliary Nitinol Stent Using Argon Plasma  

Microsoft Academic Search

Metallic stent migration is a well-known complication which cannot always be managed by removal or repositioning, especially in case of uncovered stent. We report a patient who developed obstructive jaundice due to migration of an expandable metallic stent (EMS) inserted in the lower bile duct. Trimming of the EMS using argon plasma was performed, with the power setting of 60

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

2009-01-01

49

A CFD STUDY OF HYPERSONIC WEAKLY IONIZED ARGON PLASMA FLOW  

Microsoft Academic Search

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

Tarit K. Bose

50

Opacity measurements in shock-generated argon plasmas  

SciTech Connect

Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

Erskine, D.

1993-07-01

51

Analysis of the expanding thermal argon oxygen plasma gas phase  

NASA Astrophysics Data System (ADS)

An expanding thermal argon plasma into which oxygen is injected has been analysed by means of Langmuir and Pitot probe measurements. Information is obtained on the ion density profile and the flow pattern in the downstream plasma. A combination of Langmuir and Pitot probe measurements provide information on the total ion flux generated by the plasma source (cascaded arc). It has been found that the ion diffusion is mainly determined by the background pressure in the expansion vessel and the arc current. The ion density is determined by the total power input into the plasma as well as the gas flow in the plasma source. There is an optimum in the power transfer used for ionization from plasma source to the feed gas. Interaction of oxygen with the plasma results in a decrease in the argon ion density and the plasma beam radius. The recirculation pattern of the downstream plasma has been investigated experimentally using the Pitot probe. Due to the low downstream pressure (10-30 Pa), the conventional compressible Pitot probe theory no longer applies. It is concluded that viscous effects start to play an important role at these low pressures and should be taken into account in the analysis of the Pitot probe measurements.

van Hest, M. F. A. M.; Haartsen, J. R.; van Weert, M. H. M.; Schram, D. C.; van de Sanden, M. C. M.

2003-11-01

52

The interaction of an atmospheric pressure plasma jet using argon or argon plus hydrogen peroxide vapour addition with bacillus subtilis  

NASA Astrophysics Data System (ADS)

This paper reports that an atmospheric pressure dielectric barrier discharge plasma jet, which uses argon or argon + hydrogen peroxide vapour as the working gas, is designed to sterilize the bacillus subtilis. Compared with the pure argon plasma, the bacterial inactivation efficacy has a significant improvement when hydrogen peroxide vapour is added into the plasma jet. In order to determine which factors play the main role in inactivation, several methods are used, such as determination of optical emission spectra, high temperature dry air treatment, protein leakage quantification, and scanning electron microscope. These results indicate that the possible inactivation mechanisms are the synergistic actions of chemically active species and charged species.

Deng, San-Xi; Cheng, Cheng; Ni, Guo-Hua; Meng, Yue-Dong; Chen, Hua

2010-10-01

53

Surface decontamination using atmospheric oxygen-argon plasma  

Microsoft Academic Search

This study reports on the efficacy of atmospheric oxygen-argon plasma for bio-decontamination or surface sterilization of infectious agents, such as Bacillus anthracis [Sterne] (Anthrax), MS-2 bacteriophage, and E coli. A 10- second exposure (RF power 77 W, 29.5 mL O2\\/min, 28 L Ar\\/min) on the B. a. spores revealed an average post-exposure log reduction (LR) value of 2.7, whereas a

P. C. Guschl; R. F. Hicks; M. A. Sloan

2008-01-01

54

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

55

Trimming of a Migrated Biliary Nitinol Stent Using Argon Plasma  

PubMed Central

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

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

2009-01-01

56

Trimming of a Migrated Biliary Nitinol Stent Using Argon Plasma.  

PubMed

Metallic stent migration is a well-known complication which cannot always be managed by removal or repositioning, especially in case of uncovered stent. We report a patient who developed obstructive jaundice due to migration of an expandable metallic stent (EMS) inserted in the lower bile duct. Trimming of the EMS using argon plasma was performed, with the power setting of 60 W and 2.0 l/min of argon flow. The distal part of the EMS was removed and mechanical cleaning using balloon catheter was performed for remnant EMS. Without additional stent insertion, jaundice was relieved in a few days. No complication was recognized during the procedure and no recurrence of jaundice in the rest of his life. PMID:21103276

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

2009-01-01

57

Two-temperature transport coefficients in argon helium thermal plasmas  

NASA Astrophysics Data System (ADS)

The knowledge of two-temperature transport coefficients is of interest in the modelling of flow in plasma processes and heat transfer. The transport coefficients in argon-helium plasmas at atmospheric pressure are calculated assuming that the kinetic electron temperature, Te, is different from that of the heavy species, Th. The electrical conductivity, the viscosity, the total thermal conductivity and the combined diffusion coefficients are calculated up to 30 000 K. The influence of the molar percentage of argon as well as that of the non-equilibrium parameter thgr = Te/Th are investigated. The plasma composition is calculated using the modified Saha equation of van den Sanden et al. The most recent data to obtain collision integrals are also presented. It is shown that the viscosity and the combined diffusion coefficients strongly depend on thgr, through the plasma composition and the collision integrals. The ion-dominated regime occurs all the more quickly as thgr is high, resulting in a regime of interactions between charged species which induces a decrease of the viscosity and the combined diffusion coefficients. The electrical conductivity, which is directly linked to the electron number density, and the thermal conductivity increase as thgr increases.

Aubreton, J.; Elchinger, M. F.; Rat, V.; Fauchais, P.

2004-01-01

58

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

59

Diamond-like carbon thin films prepared by ECR argon plasma assisted pulsed laser deposition  

Microsoft Academic Search

Diamond-like carbon films were prepared by pulsed laser ablation of graphite target in argon plasma produced from electron cyclotron resonance (ECR) microwave discharge and analyzed by Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The analysis shows that the films prepared with argon plasma assistance have different chemical structure compared with the films prepared in vacuum without plasma assistance. The

A. M. Wu; J. Sun; X. K. Shen; N. Xu; Z. F. Ying; Z. B. Dong; J. D. Wu

2006-01-01

60

Generation of argon-ion mixed silicon plasmas forming argon encapsulated silicon clusters  

SciTech Connect

An inductively coupled argon (Ar) plasma is superimposed on a silicon (Si) plasma generated by an electron beam gun in order to realize the formation of gas-atom encapsulated Si cage clusters. The Si clusters, which are formed and deposited on a substrate, are analyzed by laser-desorption time-of-flight mass spectrometry and are found to have the mass spectra of not only pure Si cluster (Si{sub n}; n=1-17) but also Si cluster doped with Ar atom (ArSi{sub n}; n=10-20) in the case that the large amount of Ar ions is generated in addition to the Si plasma. Together with the analysis of x-ray photoelectron spectroscopy, it is revealed that the Ar atom is included in the Si cluster, forming the structure of endohedral Ar at Si{sub n} complexes. Furthermore, the mass spectrum of Ar at Si{sub n} indicates the existence of the magic numbered cluster size n=15, 16 similar to the metal encapsulated Si clusters.

Kaneko, T.; Takaya, H.; Hatakeyama, R. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan)

2006-12-11

61

Effect of the levitating microparticle cloud on radiofrequency argon plasma  

SciTech Connect

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. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, 85741, Garching (Germany)

2010-06-16

62

Effect of the levitating microparticle cloud on radiofrequency argon plasma  

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

63

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

64

An Experimental Determination of the Thermal and Electrical Conductivity of Atmospheric Argon Plasma.  

National Technical Information Service (NTIS)

A wall stabilized arc was used to produce an equilibrium, cylindrically symmetric, argon plasma column. It was demonstrated that axial temperature gradients are negligible over a significant length of the plasma column, thus verifying the assumption that,...

C. F. Knopp

1965-01-01

65

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

NASA Astrophysics Data System (ADS)

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

Uhm, Han S.; Lim, Jin P.; Li, Shou Z.

2007-06-01

66

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

SciTech Connect

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

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

2007-06-25

67

Nonthermal atmospheric argon plasma jet effects on Escherichia coli biomacromolecules.  

PubMed

Nonthermal atmospheric plasma jet, a promising technology based on ionized gas at low temperatures, can be applied for disinfection of contaminated surfaces. In this study, Escherichia coli cells and their macromolecules were exposed to the nonthermal atmospheric argon plasma jet for different time durations. Total protein, genomic DNA, and malondialdehyde (MDA) levels of E. coli were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining; agarose gel electrophoresis; and measurement of absorbance at 534 nm, respectively. After exposure, the spectroscopic results of liquid samples indicated that the survival reduction of E. coli can reach to 100 % in an exposure time of 600 s. Moreover, inactivation zones of E. coli, DNA degradation, and MDA levels were significantly increased. Additionally, banding patterns of total protein were changed and amino acid concentrations increased following ninhydrin test. The experimental results suggest that the nonthermal plasma could serve as an effective instrument for both sterilizing E. coli and degrading macromolecules from the surface of the objects being sterilized. PMID:23982422

Hosseinzadeh Colagar, Abasalt; Memariani, Hamed; Sohbatzadeh, Farshad; Valinataj Omran, Azadeh

2013-12-01

68

Surface modification of perfluorosulfonic acid membranes with perfluoroheptane (C 7F 16)\\/argon plasma  

Microsoft Academic Search

This research focuses on the surface modification of a perfluorosulfonic acid (PFSA) membrane using plasma treatment. The plasma gas was a mixture of perfluoroheptane (C7F16) and argon (Ar). The results indicated that the plasma mixture led to the deposition of a thin fluorocarbon polymerized top layer onto the PFSA membrane. The effects of plasma operating conditions (plasma power, reactor pressure,

Shingjiang Jessie Lue; Shiang-Yiaw Hsiaw; Ta-Chin Wei

2007-01-01

69

Numerical modelling of the nonequilibrium expansion process of argon plasma flow through a nozzle  

NASA Astrophysics Data System (ADS)

A two-temperature thermal and chemical nonequilibrium model is developed and applied to investigate the expansion processes of an argon plasma flow through a Laval nozzle. This model describes in a self-consistent manner the gas flow and heat transfer, the coupling of the electric energy deposited into the plasma, and the reaction kinetics including the contribution of excited species. It is found that the plasma is far from thermodynamic equilibrium in the entire argon plasma flow expansion process through a nozzle. Significant temperature discrepancies between electrons and heavy species are found in the cooler outer region. The dominant chemical kinetic processes in different plasma gas expansion regions are presented and discussed. It is noted that although the number density of excited argon atoms (Ar*) is much lower than that of other species in the argon plasma, Ar* play important roles in the ionization and recombination processes, and in arc attachment to the anode.

Wei, Fu-Zhi; Wang, Hai-Xing; Murphy, A. B.; Sun, Wei-Ping; Liu, Yu

2013-12-01

70

Numerical simulation of nonequilibrium effects in an argon plasma jet  

SciTech Connect

Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two-dimensional numerical simulations. Electrons, ions, and excited and ground states of neutral atoms are represented as separate chemical species in the mixture. Transitions between excited states, as well as ionization/recombination reactions due to both collisional and radiative processes, are treated as separate chemical reactions. Resonance radiation transport is represented using Holstein escape factors to simulate both the optically thin and optically thick limits. The optically thin calculation showed significant underpopulation of excited species in the upstream part of the jet core, whereas in the optically thick calculation this region remains close to local thermodynamic equilibrium, consistent with previous experimental observations. Resonance radiation absorption is therefore an important effect. The optically thick calculation results also show overpopulations (relative to equilibrium) of excited species and electron densities in the fringes and downstream part of the jet core. In these regions, however, the electrons and ions are essentially in partial local thermodynamic equilibrium with the excited state at the electron temperature, even though the ionized and excited states are no longer in equilibrium with the ground state. Departures from partial local thermodynamic equilibrium are observed in the outer fringes and far downstream part of the jet. These results are interpreted in terms of the local relative time scales for the various physical and chemical processes occurring in the plasma.

Chang, C.H.; Ramshaw, J.D. (Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States))

1994-11-01

71

Activated plasma coagulation ?-Factor XII-induced vasoconstriction in rats  

PubMed Central

By inducing BK (bradykinin)-stimulated adrenomedullary catecholamine release, bolus injection of the ?-fragment of activated plasma coagulation Factor XII (?-FXIIa) transiently elevates BP (blood pressure) and HR (heart rate) of anaesthetized, vagotomized, ganglion-blocked, captopril-treated bioassay rats. We hypothesized that intravenous infusion of ?-FXIIa into intact untreated rats would elicit a qualitatively similar vasoconstrictor response. BN (Brown Norway) rats received for 60 min either: (i) saline (control; n=10); (ii) ?-FXIIa (85 ng/min per kg of body weight; n=9); or (iii) ?-FXIIa after 2ADX (bilateral adrenalectomy; n=9). LV (left ventricular) volume and aortic BP were recorded before (30 min baseline), during (60 min) and after (30 min recovery) the infusion. TPR (total peripheral resistance) was derived from MAP (mean arterial pressure), SV (stroke volume) and HR. Saline had no haemodynamic effects. ?-FXIIa infusion increased its plasma concentration 3-fold in both groups. In adrenally intact rats, ?-FXIIa infusion increased MAP by 6% (5±2 mmHg) and TPR by 45% (0.50±0.12 mmHg/ml per min), despite falls in SV (?38±8 ?l) and HR [?18±5 b.p.m. (beats/min)] (all P<0.05). In 2ADX rats, ?-FXIIa had no HR effect, but decreased SV (?89±9 ?l) and MAP (?4±1 mmHg), and increased TPR by 66% (0.59±0.15 mmHg/ml per min) (all P<0.05). After infusion, adrenally intact rats exhibited persistent vasoconstriction (MAP, 10±1 mmHg; TPR, 0.55±0.07 mmHg/ml per min; both P<0.05), whereas in 2ADX rats, MAP remained 5±1 mmHg below baseline (P<0.05) and TPR returned to baseline. End-study arterial adrenaline (epinephrine) concentrations in the three groups were 1.9±0.6, 9.8±4.1 and 0.6±0.2 nmol/l respectively. Thus, in neurally intact lightly anaesthetized untreated rats, ?-FXIIa infusion induces both adrenal catecholamine-mediated and adrenally independent increases in peripheral resistance.

Papageorgiou, Peter C.; Yeo, Erik L.; Backx, Peter H.; Floras, John S.

2012-01-01

72

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

73

The nature of fluctuations in a double arc argon-nitrogen plasma jet  

SciTech Connect

The dynamic behavior of the double arc argon-nitrogen plasma jet is investigated by combined means of the fast Fourier transform, correlation function, and Wigner distribution. The restrike mode is identified as the fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which indicates that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the power supply undulation and both arc roots motion on the anode channels. It is further found that the double anode torch could inhibit and reduce the restrike phenomenon.

Tu Xin; Yan Jianhua; Yu Liang; Cen, Kefa; Cheron, Bruno [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China); UMR 6614 CNRS CORIA, Saint Etienne du Rouvray 76801 (France)

2007-09-24

74

Modeling on the Momentum and Heat\\/Mass Transfer Characteristics of an Argon Plasma Jet Issuing into Air Surroundings and Interacting with a Counter-Injected Argon Jet  

Microsoft Academic Search

Modeling study is performed to reveal the momentum and heat\\/mass transfer characteristics of a turbulent or laminar plasma\\u000a reactor consisting of an argon plasma jet issuing into ambient air and interacting with a co-axially counter-injected argon\\u000a jet. The combined-diffusion-coefficient method and the turbulence-enhanced combined-diffusion-coefficient method are employed\\u000a to treat the diffusion of argon in the argon–air mixture for the laminar

Hai-Xing WangXi; Xi Chen; He-Ping Li

2011-01-01

75

Diode Laser Based LIF Diagnostics for Argon and Helium Plasmas.  

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

76

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

77

Effect of gamma irradiation with 30 gy on the coagulation system in leukoreduced fresh frozen plasma  

PubMed Central

Background Fresh Frozen Plasma (FFP) is a blood component prepared from whole blood or from apheresis donation. Donor leukocytes including lymphocytes are present in FFP in significant numbers inspite of freezing, responsible for Transfusion Associated Graft versus Host Disease (TA-GvHD). Study design and methods 75 units of FFP prepared at our centre were analysed. After thawing of FFP a small aliquot was made under sterile conditions and another after irradiating the product. In both the parts, variables of haemostasis were measured in parallel, using automated coagulation analyser. Activated partial thromboplastin time (APTT), prothrombin time (PT), International Normalized Ratio (INR), Thrombin time (TT), coagulation factors FI, FII, FV, FVIII, FIX, FX, FXI, FXII, vWF Ag, inhibitors of coagulation (protein C & S) and d-dimer were measured. Results Gamma irradiation of FFP with 30 Gy resulted in weak activation of coagulation system which was evident in the form of shortening of PT, APTT and TT. The activity of coagulation factors FIX, FX, FXI, and FXII were significantly raised after irradiation. No reduction in the activity of inhibitors of coagulation (protein C & S) or increase in d-dimers was observed following irradiation of FFP. Conclusion Gamma irradiation of FFP with 30 Gy resulted in a significant but very weak alteration of coagulation system in FFP.

Sarkar, R.S.; Philip, J.; Prathip Kumar, B.R.; Pathak, Amardeep

2012-01-01

78

Argon plasma-assisted PDMS-LTCC bonding technique for microsystem applications  

NASA Astrophysics Data System (ADS)

A method for transparent polymer (polydimethylosiloxane, PDMS) to glass-covered low-temperature co-fired ceramics (LTCC) using microwave argon plasma is reported in this paper. Changes in the composition of both materials before and after plasma treatment are investigated with x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy-attenuated total reflection and contact angle measurements. The results obtained for PDMS and glass-covered LTCC modified with argon plasma are compared with previously reported results received for oxygen plasma. Moreover, a comparison of adhesion between PDMS and glass-covered LTCC bonded together using Ar and O2 plasma is made using a material testing machine.

Malecha, Karol; Gancarz, Irena; Tylus, W?odzimierz

2010-11-01

79

Preparation of mesoporous silica films using sol–gel process and argon plasma treatment  

Microsoft Academic Search

This Letter demonstrates the first attempt of using sol–gel technique in combination with argon plasma calcination for the preparation of mesoporous silica films. CTAB is used as an organic template to generate the porous structure upon removal by the argon plasma treatment. Field emission scanning electron microscope, Fourier transform infrared spectroscopy, small angle X-ray scattering, N2-sorption experiment and nanoindentation technique

Alagappan Palaniappan; Jian Zhang; Xiaodi Su; Francis E. H. Tay

2004-01-01

80

SOME TRANSPORT PROPERTIES IN PLASMAS CONTAINING ARGON AND FLUORINE UDC 533.92  

Microsoft Academic Search

In this paper some results of numerical evaluation of transport coefficients in plasmas in the mixtures of argon and fluorine are presented. These transport characteristics are given in the function of the temperature for low pressures ranging from 0,1 kPa to 1,0 kPa and for low temperatures between 500 K and 5 000 K in argon plasmas with 20% and

R N. V. Novakovi?; B. S. Mili?; S. M. Stojilkovi?

81

Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.  

PubMed

The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements. PMID:23794223

Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

2013-09-01

82

Rotational, Vibrational and Electronic Excitation of a Neutral Nitrogen Molecule in the ICP (Inductively Coupled Argon Plasma),  

National Technical Information Service (NTIS)

Diagnostics of nitrogen molecules in the inductively coupled argon plasma (ICP) have been evaluated with respect to collisional processes with electrons, argon atoms, and nitrogen molecules. Based on reaction probabilities, defined as the product of the r...

T. Hasegawa J. D. Winefordner

1987-01-01

83

Inhibition of plasma coagulation and platelet aggregation with structural analogs of taurine chloramine.  

PubMed

We studied the effects of amide and N-alkyl analogs of taurine chloramine on rabbit plasma coagulation and platelet aggregation. Alkyl analog N-isopropyl-N-chlorotaurine produced greater increase in plasma coagulation time after its activation by the contact method or with thrombin than amide analog N-propionyl-N-chlorotaurine. In case of coagulation induced by the tissue factor, the test analogs produced similar effect. Inhibition of platelet aggregation in platelet-rich plasma under the effect of N-isopropyl-N-chlorotaurine depended on the nature of the agonist. Aggregation was suppressed stronger under conditions of collagen stimulation than in response to ADP agonist. Estimated partial charges of the chlorine atom in amide analogs were 5-fold higher than in N-alkyl analogs. This fact determined the difference in the chemoselective interaction with sulfur-containing amino acid residues in targets and the specific features of anticoagulation and antiaggregant effects of two analogs of taurine chloramine. PMID:24952487

Murina, M A; Roshchupkin, D I; Kondrashova, K V; Sergienko, V I

2014-06-01

84

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

85

Dielectric properties in microwave remote plasma sustained in argon: Expanding plasma conditions  

SciTech Connect

This work is devoted to the study of the relative permittivity in argon expanding plasma produced below a microwave discharge sustained in a quartz tube and working at 2.45 GHz. We discuss results and explain the microwave propagation within the reactor, outside the quartz tube. It is shown that at low pressures (133 Pa) and at powers ranging from 100 W to 400 W, the wave frequency remains lower than the plasma frequency anywhere in the expanding plasma. Under these conditions, the real part of the relative permittivity is negative and the wave is reflected. Surprisingly, in these conditions, the plasma is produced inside and outside the quartz tube, below the wave launcher. This effect can be explained considering a surface wave propagating at the surface of the quartz tube then into the reactor, on the external surface of the expanding plasma below the quartz tube.

Jauberteau, J. L.; Jauberteau, I. [UMR 7315 CNRS, SPCTS, 12 rue Atlantis, 87068 Limoges (France)

2012-11-15

86

Mode operation of inductively-coupled argon plasmas studied by optical emission spectroscopy  

Microsoft Academic Search

Mode operation of inductively driven plasmas in argon gas at low pressures is studied by optical emission spectroscopy. The plasma source is a tandem type source with a driver and an expansion plasma region. The driver region of the discharge is in the classical form of a cylindrically shaped inductive discharge, with a coil positioned over a gas discharge tube.

S. Iordanova; I. Koleva

2007-01-01

87

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

NASA Astrophysics Data System (ADS)

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 O2/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, Shou-Zhe; Wu, Qi; Yan, Wen; Wang, Dezhen; Uhm, Han S.

2011-10-01

88

Methylmethacrylate bone cement surface does not promote platelet aggregation or plasma coagulation in vitro  

Microsoft Academic Search

Leakage of viscous bone cement into venous blood possibly resulting in pulmonary embolism may occur during percutaneous vertebroplasty. Our aim was to study if bone cement surface or cement liquid component could induce platelet aggregation or plasma coagulation in vitro. Two types of commonly used methyl-methacrylate bone cement, Palacos R (Heraeus Kulzer, Germany) and Vertebroplastic TM (DePuy, Acro Med, England),

Aleš Blinc; Mojca Boži?; Rok Vengust; Mojca Stegnar

2004-01-01

89

[Experimental investigation on plasma assistant combustion actuator in argon/air].  

PubMed

In order to obtain the characteristics of argon/air plasma assistant combustion actuators, experiments of three different actuators with normal, paratactic and meshy electrode configurations were respectively performed in argon/air mixture firstly, the results showed that the shape of electrode has little influence on the discharge characteristics. Then normal electrode was applied to study spectrum and discharge characteristics under the condition of 100% air and 10% argon/90% air. The comparison showed that, though in mixture the law of discharge characteristic was the same as that of pure air, discharge current and emission spectrum were strengthened, and initial discharge voltage reduced from 27 to 24 kV. PMID:22512154

Du, Hong-liang; He, Li-ming; Ding, Wei; Zhao, Bing-bing; Wang, Feng

2012-02-01

90

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

91

Argon-plasma-induced InAs\\/InGaAs\\/InP quantum dot intermixing  

Microsoft Academic Search

We report the first study of argon (Ar)-plasma-enhanced intermixing of InAs\\/InGaAs\\/InP self-assembled quantum dots (QDs) in an inductively coupled plasma reactive ion etch system. The Ar-plasma exposure creates point defects, which propagate into the QD structure and enhance the intermixing between the QDs and their barrier layers, hence tuning the energy bandgap of the QDs. By optimizing the plasma exposure

Zongyou Yin; Xiaohong Tang; Chee-Wei Lee; Jinghua Zhao; Sentosa Deny; Mee-Koy Chin

2006-01-01

92

Preparation of mesoporous silica films using sol?gel process and argon plasma treatment  

NASA Astrophysics Data System (ADS)

This Letter demonstrates the first attempt of using sol-gel technique in combination with argon plasma calcination for the preparation of mesoporous silica films. CTAB is used as an organic template to generate the porous structure upon removal by the argon plasma treatment. Field emission scanning electron microscope, Fourier transform infrared spectroscopy, small angle X-ray scattering, N 2-sorption experiment and nanoindentation technique are used for characterization. Results show that the obtained films have identical chemical structure and comparable mechanical properties with those prepared using thermal calcination. The plasma parameters have distinct influences on the thickness and mesoporous property of the films.

Palaniappan, Alagappan; Zhang, Jian; Su, Xiaodi; Tay, Francis E. H.

2004-09-01

93

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

Microsoft Academic Search

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

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

1997-01-01

94

Numerical study on iron particles behaviour injected in an argon plasma from an electric transferred arc.  

National Technical Information Service (NTIS)

In the scope of the Research and Development Project 'Control of Plasma/Product Interaction', the aim of this study is to analyze the behaviour of iron particles injected in an argon plasma flow from an electric transferred arc. It includes particle traje...

A. Douce I. Flour

1995-01-01

95

Characterization of an atmospheric double arc argon-nitrogen plasma source  

SciTech Connect

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

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

2008-05-15

96

Langmuir probe measurements in expanding magnetized argon, nitrogen and hydrogen plasmas  

Microsoft Academic Search

Langmuir probe measurements are performed in magnetized expanding plasmas of different eompositions. The influence of the magnetic field on the currents collected by the probe in an argon plasma is investigated at two different flows and for two different probe sizes. The experimental results are compared to existing theories. The theoretically predicted dependence of the ratio of electron to ion

G. J. H. Brussaard; M. van der Steen; M. Carrère; D. C. Schram

1998-01-01

97

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

98

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

99

Species Densities and Temperatures in an Argon-Acetylene RF Plasma using Mass Energy Analysis  

NASA Astrophysics Data System (ADS)

We report species measurements made with a Hiden EQP Mass Energy Analyser in a Diamond like Carbon Plasma Enhanced Physical Vapour Deposition system. Argon/acetylene fractions of 0% to 100% argon, pressures from 3 to 20 mTorr and RF powers up to 180 W ( ˜500 V d.c. bias), were used, concentrating near optimum DLC deposition conditions (10 sccm argon, 20 sccm acetylene, 7 mTorr, 150 W, 450 V dc bias). Initial neutral species results show, for all RF powers, at constant chamber pressure, altering the argon fraction causes the expected linear variation in argon and acetylene count rate. For a 33% argon fraction at near constant pressure ( ˜7 mTorr), however, acetylene count rates fall significantly as RF power is raised, argon count rates are almost constant. If the drop in total count rate (and thus number density) at constant pressure is due to a neutral temperature rise, it implies a temperature of 300 C at 160 W. Ionic species/energy measurements and comparison of species density with deposition rate will also be presented.

Mahony, C. M. O.; McPeake, G. L.; Maguire, P. D.

2004-09-01

100

On the effect of treating poly(acrylic acid) with argon and tetrafluoromethane plasmas: Kinetics and degradation mechanism  

Microsoft Academic Search

Poly(acrylic acid) (PAAc) films were treated with either an argon or a tetrafluoromethane (CF4) plasma and subsequently analyzed with X-ray photoelectron spectroscopy (XPS). PAAc films were decarboxylated during both types of plasma treatments. In addition, during the CF4 plasma treatment, the PAAc films became fluorinated. The plasma phase during the argon plasma treatment of PAAc films was investigated with optical

Johannes G. A. Terlingen; Gijsbert A. J. Takens; Gaag van der Frederik J; Allan S. Hoffman; Jan Feijen

1994-01-01

101

[Coagulation changes during aortofemoral bifurcation bypass: is volume and plasma substitution possible with hydroxyethyl starch alone?].  

PubMed

The study explored the possibility of eliminating the need for plasma replacement with expensive human albumin (HA) and fresh frozen plasma (FFP) and instead using hydroxyethyl starch (HES). Patients undergoing infrarenal aortofemoral bifurcation grafting were randomly assigned to one group, which received FFP and HA, or another group, which received HES as volume replacement. Blood specimens were collected at five time intervals: preoperatively, prior to cross-clamping of the aorta, prior to declamping, at the end of the operation, and 6 h postoperatively. Preoperative coagulation values were all within normal limits. The basic coagulation tests were generally affected by the standardized heparin dose of 5000 IU administered during the clamping phase. Euglobulin lysis demonstrated a perioperative climb that was particularly marked within the HES group at the time of clamping. Values returned to initial levels 6 h postoperatively. Plasminogen, fibrinogen, antithrombin III, and antiplasmin concentrations fell significantly in both groups; 10% to 20% lower values were determined within the HES group due to the lack of factor substitution. The reduction in the coagulation factors can be explained as a dilution effect, but there are also signs of a consumption reaction taking place at the onset of the operation involving activation of coagulation and fibrinolysis. Restricting the use of FFP and simultaneously increasing HES administration is justifiable in procedures involving the abdominal aorta with moderate blood loss. PMID:1696795

von Sommoggy, S; Fraunhofer, J; Jelen-Esselborn, S; Stemberger, A

1990-07-01

102

Application of a wall-stabilized argon plasma arc for the determination of some volatile hydride-forming elements  

Microsoft Academic Search

Volatile hydrides of As, Se, Sb and Sn, produced by a continuous manifold hydride generator, have been swept with argon and injected into the plasma of home-made direct current wall-stabilized argon plasma arc via one of its stabilizing segments. The arc burns in argon with an arc current of 20 A and a cathode-anode voltage of 40 V. Measurements were

M. A. Eid; H. R. Moustafa; E. A. Al Ashkar; S. S. Ali

2006-01-01

103

Dependence of Plasma Focus Argon Soft X-Ray Yield on Storage Energy, Total and Pinch Currents  

Microsoft Academic Search

Numerical experiments are carried out systematically to determine the argon soft X-Ray yield Ysxr for optimized argon plasma focus with storage energy E0 from 1 kJ to 1 MJ. The ratio c = b\\/a, of outer to inner radii; and the operating voltage V0 are kept constant. E0 is varied by changing the capacitance C0. These numerical experiments were investigated on argon plasma focus

M. Akel; S. Lee

104

Electron number density measurement on a DC argon plasma jet by stark broadening of Ar I spectral line  

Microsoft Academic Search

In thermal plasma processing, input power and gas flow rate play a major role in controlling the plasma jet temperature, velocity and density. Emission spectroscopy study is an important method for plasma diagnostics. A DC atmospheric plasma spray torch was operated at different power levels and flow rates of plasma gas (argon). Electron number density of the plasma jet, the

S. Yugeswaran; V. Selvarajan

2006-01-01

105

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

NASA Astrophysics Data System (ADS)

We have reported the argon (Ar) plasma waveguide produced in an alumina (Al2O3) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 1016 W/cm2. The electron density in the plasma waveguide was measured to be 1×1018 cm-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 Ar3+ 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 Ar3+ 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; Bobrova, Nadezhda; Sasorov, Pavel; Sakai, Shohei; Sentoku, Yasuhiko; Kodama, Ryosuke; Yugami, Noboru

2012-05-01

106

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

NASA Astrophysics Data System (ADS)

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

Chatterjee, Kaushik

107

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

108

Characterization of Air-Nitrogen-Argon DC Glow Discharge Plasma with THz Time Domain Spectroscopy  

NASA Astrophysics Data System (ADS)

Transmission of terahertz pulses through DC glow discharge plasma was investigated for different gases. The pressure was kept in between the range of 0.1 torr-0.5 torr and for each pressure different measurements were taken at 5 mA, 10 mA and 15 mA plasma currents. Moreover, emission spectrum of Air, N2 and Ar plasma analysis were done respectively. It was found that the transmission of terahertz pulses through nitrogen plasma was considerably affected compared to that of the argon plasma.

Karaoglan, G.; Tosun, Z.; Akbar, D.; Altan, H.

109

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

110

Effect of Oxygen Injection on Argon Induction Plasmas by Chemically Non-equilibrium Modeling  

NASA Astrophysics Data System (ADS)

Thermal plasmas have simply been used as a high temperature source. This indicates that thermal plasmas may have more capabilities in material processing, especially production of high-quality and high-performance materials, if thermal plasmas are utilized effectively as chemically reactive gases. Therefore, characteristics of thermal plasmas with chemically reactive gas should be investigated. The purpose of this work is to investigate the effective injection location of oxygen into argon induction plasmas. A non-equilibrium modeling of argon-oxygen induction thermal plasmas was performed without chemical equilibrium assumptions. The thermofluid and concentration fields were obtained by solving of two-dimensional modeling. Chemical reaction kinetics rates of the dissociation and recombination as well as the ionization were taken into account in this modeling. The transport properties were estimated using Chapman-Enskog method with higher order of Sonine polynomial expansion with collision integrals at each of the calculation step. As a result, the high-temperature region and high-concentration region of dissociated oxygen spread toward the wall in the chemically non-equilibrium model. Deviation from the LTE assumption at the coil region is not negligible in argon-oxygen induction plasmas under atmospheric pressure.

Atsuchi, Nobuhiko; Shigeta, Masaya; Watanabe, Takayuki

2004-09-01

111

Sterilization of microorganisms in silk fabrics by microwave-induced argon plasma treatment at atmospheric pressure  

Microsoft Academic Search

Since many old cultural assets, such as clothes, pictures and books, remain in the state of silk fabrics or papers, it is very difficult as well as important to retain their original form. Microbial contamination induces surface deformations and strength degradation of silk fabrics by invading deeply into the fibers. In this study, the sterilization effects of microwave-induced argon plasma

Dong Jeong Park; Mi Hee Lee; Yeon I Woo; Dong-Wook Han; Jae Bong Choi; Jeong Koo Kim; Soon O. Hyun; Kie-Hyung Chung; Jong-Chul Park

2008-01-01

112

Comparison of Various NLTE Codes in Computing the Charge-State Populations of an Argon Plasma.  

National Technical Information Service (NTIS)

A comparison among nine computer codes shows surprisingly large differences where it had been believed that the theory was well understood. Each code treats an argon plasma, optically thin and with no external photon flux; temperatures vary around 1 keV a...

S. R. Stone J. C. Weisheit

1984-01-01

113

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...

114

Time resolved optical emission spectroscopy of an inductively coupled plasma in argon and oxygen  

Microsoft Academic Search

We present the space-time resolved excitation data for a single coil inductively coupled plasma (ICP) reactor operating in collision dominated regime in argon and oxygen at 13.56 MHz. Robot assisted scanning was used in order to obtain Abel inverted radial profiles of emission and subsequently of the net excitation rate as well as the number density of excited states. The

Masahiro Tadokoro; Hajime Hirata; Nobuhiko Nakano; Zoran Lj. Petrovic; Toshiaki Makabe

1998-01-01

115

Modification of the near surface layer of carbon steels with intense argon and nitrogen plasma pulses  

Microsoft Academic Search

Series of carbon steels with various contents of carbon were irradiated with high intensity (5–6Jcm?2), short (?s range) nitrogen and argon plasma pulses. In all samples the near surface layer of the thickness in ?m range was melted. The paper reports the results of investigation of changes induced by such treatment. The identified phases, profiles of retained nitrogen concentration, microhardness

B. Sartowska; J. Piekoszewski; L. Wali?; W. Szymczyk; J. Stanis?awski; L. Nowicki; R. Ratajczak; M. Kopcewicz; J. Kalinowska; M. Barcz; F. Prokert

2005-01-01

116

Fundamental Studies and Spectral Simulation of the Inductively Coupled Argon Plasma  

Microsoft Academic Search

The objectives of this work are twofold: firstly, to understand the inductively coupled argon plasma (icp) from a fundamental point of view and, secondly, to attempt to put that knowledge to practical use. In an effort to realize this first objective, a simple two-level rate model was developed which allows the estimation of the deviations (due to radiative decay) of

Lyle Lorrence Burton

1990-01-01

117

Structural transformation and field emission enhancement of carbon nanofibers by energetic argon plasma post-treatment  

SciTech Connect

Vertically aligned carbon nanofibers (CNFs) grown by plasma enhanced chemical vapor deposition (PECVD) were transformed into cone-shaped nanostructures after treatment by argon (Ar) plasma. Significant enhancement of field emission characteristics of the post-treated CNFs has been achieved. Analysis by electron microscopy and energy dispersive spectroscopy (EDS) suggests that the structural transformation is a result of a cosputtering/deposition process by energetic plasma ions. The enhancements can be attributed to the combining effects of an additional Si/C layer coverage, catalytic nanoparticles removal and the sharpening of CNFs tips. The argon plasma post-treatment processes developed here can be easily extended to in situ PECVD processes for fabricating CNFs based emitters.

Weng, C.H.; Leou, K.C.; Wei, H.W.; Juang, Z.Y.; Wei, M.T.; Tung, C.H.; Tsai, C.H. [Department of Engineering and System Science, National Tsing Hua University, Taiwan (China)

2004-11-15

118

Low temperature argon plasma sterilization effect on Pseudomonas aeruginosa and its mechanisms  

Microsoft Academic Search

In the present work, low temperature argon plasma was used to sterilize Pseudomonas aeruginosa on PET sheets. The discharge conditions were as follows: power of 30W and gas flux of 20cm3\\/min, and the pressure in the reaction chamber was 6.2Pa. In a self-designed plasma reaction equipment, active species (electron, ion, radical and UV light, etc.) were separated effectively, and the

Liqing Yang; Jierong Chen; Junling Gao

2009-01-01

119

Microcrystalline diamond growth in presence of argon in millimeter-wave plasma-assisted CVD reactor  

Microsoft Academic Search

The additions of argon and oxygen to H2–CH4 feed gas and high-electron-density plasma generated by the millimeter-wave power were used to deposit microcrystalline diamond films having high quality and high growth rate simultaneously. Microcrystalline diamond films were grown on silicon substrates with 60–90 mm diameter in the millimeter-wave plasma-assisted CVD reactor based on 10 kW gyrotron operating at a frequency of 30 GHz.

A. L. Vikharev; A. M. Gorbachev; A. V. Kozlov; D. B. Radishev; A. B. Muchnikov

2008-01-01

120

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

121

Effect of therapeutic plasma exchange on coagulation parameters in patients on warfarin.  

PubMed

Therapeutic plasma exchange (TPE) without plasma replacement results in coagulation factor removal. Warfarin decreases the activity of vitamin K dependent coagulation factors. The combined effect of TPE and warfarin on the coagulation system has not been studied. A prospective, observational study was conducted in patients undergoing TPE while on warfarin. One plasma volume TPEs were performed on the COBE Spectra Apheresis System (Terumo BCT, Lakewood, CO) with 5% albumin. International normalized ratio (INR), fibrinogen, and factor II activity were obtained pre and post procedure. Eight patients underwent 121 TPEs that met study criteria with pre and post data. The average pre values were INR 2.09?±?0.58, fibrinogen 263?±?76 mg/dl, and factor II 29?±?16% and the average post values were INR 4.12?±?1.44, fibrinogen 105?±?31 mg/dl, and factor II 13?±?7%. The pre-INR was ?2.00 for 55% of TPEs. The pre value (Y0 ) predicts the post value (Y) by the following equations Y?=?-0.54?+?2.21Y0 , Y =12.10?+?0.35Y0, and Y =1.83?+?0.39Y0 for INR, fibrinogen, and factor II respectively. In conclusion, pre procedure laboratory values can predict the post laboratory values for patients on warfarin receiving single plasma volume TPE with albumin replacement. The post-INR is approximately twice the pre-INR. At normal and mildly elevated pre-INR, the effect of TPE on the INR is less marked. A single plasma volume TPE decreases the plasma level by ?65% for fibrinogen and 60% for factor II. PMID:24000079

Zantek, Nicole D; Morgan, Shanna; Zantek, Paul F; Mair, David C; Bowman, Robert J; Aysola, Agnes

2014-04-01

122

High Speed Argon Plasma Jet Merging Studies In Support of PLX  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

123

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

SciTech Connect

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

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

1995-06-01

124

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

NASA Astrophysics Data System (ADS)

A nonequilibrium Ar/O2 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/O2 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

2007-09-01

125

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

126

On the multistep ionizations in an argon inductively coupled plasma  

SciTech Connect

The effect of the multistep ionizations on the plasma parameters in the inductively coupled plasma (ICP) has been investigated by experiments and theory. To obtain electron density and electron temperature precisely at various powers and pressures in the ICP, the electron energy distribution functions (EEDFs) are measured. It is found that at high pressures, the electron temperature from the EEDFs decreases and the electron density increases rapidly with the absorbed power while, at low pressures, the electron temperature is hardly changed and the electron density is almost linearly proportional to the absorbed power. The comparison between the experiment and our model including the multistep ionizations [M. H. Lee and C. W. Chung, Phys. Plasmas 12, 73501 (2005)] was done and the experiment was in close agreement with the model. This shows that the changes in the electron density and the electron temperature in the ICP are mainly due to the multistep ionizations.

Lee, Min-Hyong; Jang, Sung-Ho; Chung, Chin-Wook [Department of Electrical and Computer Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791 (Korea, Republic of)

2006-05-15

127

Transport and turbulence in a magnetized argon plasma  

NASA Astrophysics Data System (ADS)

Longitudinal and rotational drift velocities of ions in the magnetized plasma of a hollow cathode arc have been measured along with the electron and neutral densities and the temperatures of ions, electrons, and neutrals. The radial and longitudinal gradients of these quantities have been established. The occurrence of turbulence and its influence on plasma transport is theoretically and experimentally investigated, and a simple model of turbulence is obtained. The properties of a hollow cathode as an ion source are experimentally studied. Measurement results on the electron density, the ion and neutral temperature, and the drift velocity are interpreted on the basis of conservation laws for matter, momentum, and energy.

Vogels, J. M. M. J.

128

Heat flux characteristics in an atmospheric double arc argon plasma jet  

SciTech Connect

In this study, the axial evolution of heat flux excited by a double arc argon plasma jet impinging on a flat plate is determined, while the nonstationary behavior of the heat flux is investigated by combined means of the fast Fourier transform, Wigner distribution, and short-time Fourier transform. Two frequency groups (<1 and 2-10 kHz) are identified in both the Fourier spectrum and the time-frequency distributions, which suggest that the nature of fluctuations in the heat flux is strongly associated with the dynamic behavior of the plasma arc and the engulfment of ambient air into different plasma jet regions.

Tu Xin; Yu Liang; Yan Jianhua; Cen Kefa [Zhejiang University, Hangzhou 310027 (China); Cheron, Bruno [UMR 6614 CNRS CORIA, Saint Etienne du Rouvray 76801 (France)

2008-10-13

129

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

130

Endoscopic interventions for preneoplastic and neoplastic lesions: mucosectomy, argon plasma coagulation, and photodynamic therapy.  

PubMed

The classical treatment of neoplastic lesions is surgical resection. Improved detection of early lesions has offered new therapeutic strategies. Thus, for the last 20 years it has been increasingly attempted to undertake endoscopic resection of such tumors. While there is no doubt that morbidity and mortality are lower than after surgery, it was assumed that the long-term prognosis is not as good as with surgery. Surprisingly, however, the 5-year survival rates are excellent. Therefore, in local mucosal lesions of colon, stomach, and esophagus, endoscopic removal has become standard treatment. In Barrett's esophagus, the treatment modality it is still discussed controversially, despite encouraging results. Since we are yet not able to completely eliminate the premalignant specialized intestinal epithelium of the esophagus, it is still uncertain whether eradication of the malignant or dysplastic lesion is sufficient. PMID:12566619

Ortner, Maria-Anna; Dorta, Gian; Blum, André Louis; Michetti, Pierre

2002-01-01

131

Positive sheath behaviour in low pressure Argon plasma  

Microsoft Academic Search

We measure positive ions by means of a Hiden mass spectrometer (EQP 300) in a helicon discharge. Our helicon ‘PHISIS’ (plasma helicon to irradiate surfaces in situ) is used at low injected RF power, in a capacitive regime. A copper sample is centred in the expanding chamber, 40mm away from the mass spectrometer nozzle. We measure ion energy distribution function

L. Schiesko; M. Carrère; G. Cartry; J. M. Layet

2007-01-01

132

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

133

Optical Emission Measurements of AN Inductively Coupled Argon Plasma  

Microsoft Academic Search

The inductively coupled plasma (ICP) literature contains several unresolved issues. These issues are contained in the observations (1) measured excitation temperatures are constant across a wide range of operating conditions, (2) measured power dissipation profiles are significantly more localized than calculated profiles, and (3) the few available measurements of gas temperatures are made above the coil and indicate the gas

Stephen Mosheim Jaffe

1995-01-01

134

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.

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

2010-01-01

135

Dietary Fat Induces Changes in Factor VII Coagulant Activity Through Effects on Plasma Free Stearic Acid Concentration  

Microsoft Academic Search

Abstract Previous studies have demonstrated,activation of the contact system of coagulation ,and ,an increase ,in factor ,VII coagulant activity (VIIc) when,citrated plasma is incubated in the presence of micellar stearate. The products of contact activation, factors Xlla and IXa, were responsible in this system for the activation of factor VII, thereby increasing factorVIIc. To obtain evidence that these in vitro

K. a. Mitropoulos; G. j. Miller; J. c. Martin; B. e. a. Reeves; J. Cooper

136

Characteristics of an atmospheric-pressure argon plasma jet excited by a dc voltage  

NASA Astrophysics Data System (ADS)

A dc-excited plasma jet is developed to generate a diffuse plasma plume in flowing argon. The discharge characteristics of the plasma jet are investigated by optical and electrical methods. The results show that the plasma plume is a pulsed discharge even when a dc voltage is applied. The discharge frequency varies with a change in the applied voltage, the gas flow rate and the gas gap width. It is found that the discharges at different positions of the plasma plume are initiated and quenched almost at the same time with a jitter of about 10 ns by the spatially resolved measurement. Optical emission spectroscopy is used to investigate the excited electron temperature of the plasma plume. The results show that the excited electron temperature decreases with increasing applied voltage, gas flow rate or gas gap width. These results are analyzed qualitatively.

Li, Xuechen; Di, Cong; Jia, Pengying; Bao, Wenting

2013-08-01

137

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

138

Experimental Investigation of Laser-sustained Plasma in Supersonic Argon Flow  

SciTech Connect

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 CO{sub 2}-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 [DLR - German Aerospace Center, Institute of Technical Physics, Stuttgart (Germany); Moessinger, Peter [University of Applied Sciences, Faculty of Mechanical Engineering, Esslingen (Germany); Fasoulas, Stefanos [University of Stuttgart, Institute of Space Systems, Stuttgart (Germany)

2011-11-10

139

Positive sheath behaviour in low pressure Argon plasma  

NASA Astrophysics Data System (ADS)

We measure positive ions by means of a Hiden mass spectrometer (EQP 300) in a helicon discharge. Our helicon 'PHISIS' (plasma helicon to irradiate surfaces in situ) is used at low injected RF power, in a capacitive regime. A copper sample is centred in the expanding chamber, 40 mm away from the mass spectrometer nozzle. We measure ion energy distribution function (IEDF) for different sample positive bias. We show the absence of ions having energies corresponding to the full acceleration inside the positive sheath. We attribute this effect to secondary electron emission induced by electrons extracted from the plasma to the sample surface, which changes the potential profile and neutralise low energy ions created close to the sample surface (radiative recombination).

Schiesko, L.; Carrère, M.; Cartry, G.; Layet, J. M.

2007-06-01

140

Modelling of Argon-Carbon Dioxide Thermal Plasma  

Microsoft Academic Search

A chemical kinetic model has been constructed to predict the pressure and gas and electron temperature dependency of the neutral and ionic species composition in Ar-CO_2 mixtures under thermal plasma conditions. Pure Ar and Ar-C models have also been constructed as a part of this investigation. The models include electron impact, thermal impact, ion-molecule, and recombination reactions as well as

Thomas Gordon Beuthe

1992-01-01

141

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

142

RF sputtering of epitaxial lead chalcogenide films in argon and krypton plasma  

Microsoft Academic Search

The measurements of sputtering etch rates for monocrystalline (1 1 1)-oriented epitaxial films of semiconductor binary compounds PbTe, PbSe, PbS in RF high-density low-pressure inductively coupled argon and krypton plasma were performed. Films with 1-5 µm thickness were grown on Si(1 1 1) and BaF2(1 1 1) substrates using molecular beam epitaxy. Sputtering was carried out with the energy of

S. P. Zimin; I. I. Amirov; E. S. Gorlachev

2011-01-01

143

Application of RF Argon Plasma to Enhance Hydrophobic Properties of Fluoropolymer Pre-deposited Paper  

Microsoft Academic Search

Tetrafluoroethane (TFE) pre-deposited paper substrates were exposed to an inert gas (argon) plasma environment in order to convert the hydrophilic to hydrophobic surfaces via grafting and\\/or cross-linking of the fluorinated layer on the surface of paper, while also improving coating uniformity. The XPS spectrum indicates changes in the nature and relative ratios of the surface functionalities. The application of 300

Halil Turgut Sahin

2011-01-01

144

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

PubMed

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

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

2010-05-01

145

Rotational Temperatures Determined from C2 Molecular Band Spectra in a Thermal Argon Plasma Interacting with Insulating Materials  

Microsoft Academic Search

The interaction between argon plasma and an insulating material is studied in an arc chamber. Argon plasma is put in contact with insulator by means of a magnetic field produced by Helmoltz coils. Arc spectrum is analysed by means of an optical multichannel analyser (O.M.A) connected to a monochromator and a Personal Computer.The spectral analysis shows, for each insulator, the

O. Reynaud; J. P. Picard; M. J. Parizet

1995-01-01

146

Effect of oxygen addition to an argon plasma on etching selectivity of poly(methyl methacrylate) to polystyrene  

NASA Astrophysics Data System (ADS)

The effect of oxygen addition to an argon plasma on the etching selectivity of poly(methyl methacrylate) (PMMA) to polystyrene (PS) (hereafter "PMMA/PS etching selectivity") was investigated. The PMMA/PS etching selectivity was evaluated by using inductively coupled plasmas composed of argon and oxygen. The etching selectivity in the case of argon plasma was estimated to be 3.9, which is higher than that of oxygen plasma, which is 1.7. The time dependence of etching depth shows that the etching rate of PMMA is reduced to less than one half of its initial value after the etching depth exceeds 15 nm. X-ray photoelectron spectroscopy of the PMMA surface revealed that the reduction of etching rate is caused by a depletion of oxygen concentration by argon-ion bombardment. To compensate the oxygen-concentration depletion, 1% oxygen was added to the argon plasma. As a result, the reduction of PMMA etching rate was suppressed, and constant etching rate was obtained even when etching depth exceeded 50 nm. The mixed argon-oxygen plasma was used to fabricate a PS mask pattern with a full pitch in the range of 25.5 to 77 nm.

Satake, Makoto; Iwase, Taku; Kurihara, Masaru; Negishi, Nobuyuki; Tada, Yasuhiko; Yoshida, Hiroshi

2013-10-01

147

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

SciTech Connect

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

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

2007-01-29

148

Contributions of contact activation pathways of coagulation factor XII in plasma.  

PubMed

Activation of human blood plasma coagulation by contact with hydrophilic or hydrophobic surfaces (procoagulants) is dominated by kallikrein (Kal)-mediated activation of the blood zymogen FXII (Hageman Factor). Mathematical modeling of prekallikrein (PK)-deficient platelet-poor plasma (d(PK)PPP) and PK-reconstituted d(PK)PPP (Rd(PK)PPP) coagulation shows that autoactivation of FXII (FXII-->[surface]FXII) produces no more than about 25% of the total FXIIa produced by the intrinsic pathway. Autoactivation and reciprocal-activation increase in the same proportion with procoagulant surface energy (water-wettability), whereas total amount of FXIIa produced per-unit-area procoagulant remains roughly constant for any particular procoagulant. These results suggest that procoagulant surfaces initiate the intrinsic cascade by producing a bolus of FXIIa in proportion to surface energy or surface area but play no additional role in subsequent molecular events in the cascade. Results further suggest that reciprocal-activation occurs in proportion to the amount of FXIIa produced by the initiating autoactivation step. PMID:18481791

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

2009-07-01

149

Diode Laser Based LIF Diagnostic for Argon Plasmas  

NASA Astrophysics Data System (ADS)

A description of a diode laser based LIF diagnostic is presented. The LIF diagnostic features a tunable diode laser system developed for the Hot hELIcon eXperiment (HELIX) at West Virginia University. We present preliminary results for experiments conducted on Ar plasmas. The laser, tuned at 668.4 nm, is used to pump the 3d^4F_5/2 Ar II metastable level to the 4p^4D_7/2 level. The fluorescence radiation between the 4p^4D_7/2 and the 4s^4P_5/2 levels (442.6 nm) is monitored by a photomultiplier detector. The LaserTechnik SAL-665-10 laser has a Littrow external cavity. The mode-hop free tuning range is greater than 20 GHz and the total power output is about 15 mWatt. An active stabilization system using an absorption cell is used to prevent wavelength drift. Wavelength scanning is achieved by ramping the voltage on the piezoelectric controlled grating in the laser cavity. A lock-in amplifier is used to isolate the fluorescence signal from the electron-impact induced radiation.

Boivin, Robert; Kline, John; Scime, Earl; Woehrman, Micheal

2001-10-01

150

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

151

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

152

Fundamental Studies and Spectral Simulation of the Inductively Coupled Argon Plasma.  

NASA Astrophysics Data System (ADS)

The objectives of this work are twofold: firstly, to understand the inductively coupled argon plasma (icp) from a fundamental point of view and, secondly, to attempt to put that knowledge to practical use. In an effort to realize this first objective, a simple two-level rate model was developed which allows the estimation of the deviations (due to radiative decay) of analyte level populations in the icp from local thermodynamic equilibrium (lte). The results were found to agree very well with experiment for analyte elements (Fe, Cr and Ba) which did not exhibit charge transfer with the argon support gas. A comprehensive study of magnesium excited-state level populations was performed. It was found that charge transfer between argon ions and ground state magnesium atoms caused ionic magnesium to be overpopulated (with respect to the simple rate model calculations mentioned above). It was also found that, due to appreciable self -absorption, argon itself conforms to an lte model. Electron temperatures (T_{ rm e}) were measured in the icp. It was found that, for electron densities greater than about 2 times 10^{15 } cm^{-3}, T_{rm e} was within experimental uncertainty of the so-called lte temperature (T_{rm e,lte} - calculated from the electron density). At lower electron densities, due to the large experimental errors involved, it was difficult to draw definitive conclusions regarding their agreement. The plasma was also extensively characterized when an extra argon flow was added to the aerosol gas. It was found that at low values of the aerosol gas flow rate, mixing between it and the plasma gas was relatively complete, whereas at higher flow rates there was relatively little mixing. It was also found that the introduction of water into the plasma had a limited effect on sample excitation. In order to fulfil the second objective, a method was developed to simulate emission spectra from an icp. The method involved the use of a computer program, which worked by combining basic physical data for atomic species, the results of icp fundamental studies, and a realistic instrumental line profile (described in detail). The method was used to simulate a hypothetical silver determination in NBS coal fly ash showing the effects of spectrometer bandpass, silver concentration, and line choice on spectral overlaps.

Burton, Lyle Lorrence

153

Energy Loss and Charge Transfer of Argon in a Laser-Generated Carbon Plasma  

NASA Astrophysics Data System (ADS)

This Letter reports on the measurement of the energy loss and the projectile charge states of argon ions at an energy of 4MeV/u penetrating a fully ionized carbon plasma. The plasma of ne?1020cm-3 and Te?180eV is created by two laser beams at ?Las=532nm incident from opposite sides on a thin carbon foil. The resulting plasma is spatially homogenous and allows us to record precise experimental data. The data show an increase of a factor of 2 in the stopping power which is in very good agreement with a specifically developed Monte Carlo code, that allows the calculation of the heavy ion beam’s charge state distribution and its energy loss in the plasma.

Frank, A.; Blaževi?, A.; Bagnoud, V.; Basko, M. M.; Börner, M.; Cayzac, W.; Kraus, D.; Heßling, T.; Hoffmann, D. H. H.; Ortner, A.; Otten, A.; Pelka, A.; Pepler, D.; Schumacher, D.; Tauschwitz, An.; Roth, M.

2013-03-01

154

Chemical kinetics of an argon/methane plasma in a hydrogen reforming reactor  

NASA Astrophysics Data System (ADS)

We have studied the characteristics of a plasma reactor for the promotion of chemical reactions aimed to hydrogen reforming from gaseous hydrocarbons. A plasma torch-like electrode configuration was powered by a limited current, high voltage DC source. Using as process gas an argon/methane mixture at atmospheric pressure, we have produced an intermittent spark discharge which has been investigated at different operating parameters. Experimental information on the discharge have been used to perform a numerical simulation of the plasma chemical kinetics. The evolution of the gas-phase composition during and after the interaction in the discharge region was calculated under different operating conditions. The results have been used to predict the hydrogen production yield in the experiments and to study the role played by the different discharge parameters in order to determine the optimal interaction between plasma and gas mixture.

Barni, R.; Benocci, R.; Broggi, C.; Riccardi, C.

2006-08-01

155

Study of non-thermal plasma jet with dielectric barrier configuration in nitrogen and argon  

NASA Astrophysics Data System (ADS)

Dielectric barrier discharge (DBD) is advantageous in generating non-thermal plasma at atmospheric pressure, as it avoids transition to thermal arc and dispenses with costly vacuum system. It has found useful applications in treating heat-sensitive materials such as plastics and living tissue. In this work, the discharge formed between the Pyrex glass layer and the ground electrode is extruded through a nozzle to form the non-thermal plasma jet. The DBD characteristics were investigated in terms of charge transferred and mean power dissipated per cycle when operated in nitrogen and argon at various flow rates and applied voltages. These characteristics were then correlated to the dimension of the plasma jet. The mean power dissipated in the DBD was below 7 W giving an efficiency of 17 %. The length of the plasma jet was greatly limited to below 1 cm due to the configuration of the DBD system and nozzle.

Choo, C. Y.; Chin, O. H.

2014-03-01

156

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

157

A radio-frequency nonequilibrium atmospheric pressure plasma operating with argon and oxygen  

NASA Astrophysics Data System (ADS)

A capacitively coupled, atmospheric pressure plasma has been developed that produces a high concentration of reactive species at a gas temperature below 300 °C. The concentration of ground-state oxygen atoms produced by the discharge was measured by NO titration, and found to equal 1.2 vol %, or 1.2+/-0.4×1017 cm-3, using 6.0 vol % O2 in argon at 150 W/cm3. The ozone concentration determined at the same conditions was 4.3+/-0.5×1014 cm-3. A model of the gas phase reactions was developed and yielded O atom and O3 concentrations in agreement with experiment. This plasma source etched Kapton® at 5.0 ?m/s at 280 °C and an electrode-to-sample spacing of 1.5 cm. This fast etch rate is attributed to the high O atom flux generated by the plasma source.

Moravej, M.; Yang, X.; Hicks, R. F.; Penelon, J.; Babayan, S. E.

2006-05-01

158

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

159

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

SciTech Connect

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 specifically, we consider 7 different blocks of states, namely 4s, 4p, 3d, 5s, 5p, 4d, and 6s. Each block k is characterized by its effective energy uk (derived as an average energy of all levels in the block), as well as its effective g-factor and population. The argon dimmer, atomic and molecular ions are also taken into account in the model. We solve the Boltzmann equation in order to get the electron energy distribution function and the necessary rate constants of the elementary processes. The collisional-radiative part of the model is based on 87 processes. As a result we obtain the electron and ions' number densities, mean electron energy, mean power for sustaining an electron--ion pair in the discharge bulk, as well as the population of the excited blocks of states of the argon atom as functions of the gas temperature.

Pencheva, M.; Benova, E. [Department for Language Teaching and International Students, Sofia University, 27 Kosta Loulchev Street, BG-1111 Sofia (Bulgaria); Zhelyazkov, I. [Faculty of Physics, Sofia University, 5 James Bourchier Blvd, BG-1164 Sofia (Bulgaria)

2008-03-19

160

Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures  

SciTech Connect

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

Adam B. Sefkow and Samuel A. Cohen

2009-04-09

161

Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate  

NASA Astrophysics Data System (ADS)

In this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity-resonant type. The aim of research was determination of electron excitation temperature Texc gas temperature Tg and electron number density ne. All experimental tests were performed with a gas flow rate of 100 and 200 l/min and absorbed microwave power PA from 0.25 to 0.9 kW. The emission spectra at the range of 300 - 600 nm were recorded. Boltzmann plot method for argon 5p - 4s and 5d - 4p transition lines allowed to determine Texc at level of 7000 K. Gas temperature was determined by comparing the measured and simulated spectra using LIFBASE program and by analyzing intensities of two groups of unresolved rotational lines of the OH band. Gas temperature ranged 600 - 800 K. The electron number density was determined using the method based on the Stark broadening of hydrogen H? line. The measured ne rang ed 2 × 1015 - 3.5×1015 cm-3, depending on the absorbed microwave power. The described MPS works very stable with various working gases at high flow rates, that makes it an attractive tool for different gas processing.

Miotk, R.; Hrycak, B.; Jasinski, M.; Mizeraczyk, J.

2012-12-01

162

Time-resolved emission spectroscopy in laser-generated argon plasmas—determination of Stark broadening parameters  

Microsoft Academic Search

We have investigated time-resolved emission spectra of neutral argon lines in a pulsed laser-generated argon plasma source at atmospheric pressure. Depending on time after spark ignition, electronic excitation tempera- tures between roughly 5600 and 9600 K are observed. Electron density values between 0.6 and 2:3×1016 cm?3 are determined from Griem's theory of Stark-broadened line shapes as applied to the 703:025

L. Cadwella

163

Cylindrical stationary striations in surface wave produced plasma columns of argon  

SciTech Connect

Striations are a good example of manifestation of a glow discharge. In the present investigation, stationary striations in the surface wave produced plasma column are formed. Physical parameters (length, number, etc.) of such striations can be controlled by operating parameters. With the help of bifurcation theory, experimental results are explained by considering two-step ionization in the surface wave discharge mechanism in argon gas. It is also observed that the bifurcation parameter is a function of input power, working pressure, and tube radius.

Kumar, Rajneesh; Kulkarni, Sanjay V.; Bora, Dhiraj [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India)

2007-12-15

164

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

165

Determination of trace impurities in uranium hexafluoride by an inductively coupled argon plasma spectrometer  

SciTech Connect

A procedure has been developed to determine 21 trace impurity elements in uranium hexafluoride, using inductively coupled argon plasma emission spectrometry (ICAP). The method consists of a liquid-liquid extraction to separate uranium from the trace impurities with a mixture of tri-(2-ethyl-hexyl)-phosphate (TEHP) and heptane. The raffinate containing the elements is subsequently analyzed by ICAP. The impurity elements which can be analyzed by this method are: Al, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, Sb, Sn, Ti, V and Zn.

Short, B.W.; Spring, H.S.; Grant, R.L.

1983-01-06

166

Polymer processing by electron beam generated plasmas in argon, oxygen, nitrogen environments and their mixtures  

NASA Astrophysics Data System (ADS)

Polymers have unique physio-chemical properties that make them attractive for organic electronics applications. However, their inherent low surface energy can be problematic. Wet chemical processing, flames and plasma treatments have been successfully applied to alter the polymer surface properties but plasma treatments are often favored because they change only the surface without altering the bulk properties. Plasmas can also cause roughening or even surface damage. Electron beam generated plasmas have several unique features that distinguish them from the conventional discharges - intrinsically low electron temperature (< 1 eV), resulting in smaller plasma potentials and in lower incident ion energies (1-5 eV). These energies are comparable with the bond strengths found in most polymers, so they are sufficient to invoke chemical surface modification with limited morphology changes. In this study, polymer modifications resulting from electron beam plasma generation in argon, oxygen and nitrogen environments and their mixtures are investigated. The polymers of interest include polystyrene, polymethylmetacrylate and ultra-high molecular weight polyethylene. The effects of the plasma process parameters including treatment time and duty factor, as well as mixture composition on surface energy, chemistry and morphology are presented.

Lock, Evgeniya; Walton, Scott; Fernsler, Richard

2008-10-01

167

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

SciTech Connect

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

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

2011-08-15

168

XPS characterization of mica surfaces processed using a radio-frequency (rf) argon plasma  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) has been used to characterize the composition of air-cleaved mica surfaces before and after treatment under a range of different conditions in the argon rf plasma discharge. The changes in the composition of the processed surfaces that have been identified are found to depend strongly on the plasma etching parameters used. When etching was conducted at relatively high power levels (0022-3727/31/15/002/img5 W), the XPS data demonstrate that the mica surfaces examined have a significant accumulation therein of the heavier elements present, namely aluminium and silicon, whereas the oxygen component on the surface is decreased dramatically. However, no obvious changes in the chemical states of the elements contained in the mica were found for the sample surfaces processed under these conditions. Similar phenomena were also observed when the plasma etching was conducted at higher gas pressures or over prolonged etching times. The various phenomena observed are attributed mainly to the disorganization of the mica surface during etching, namely sputtering followed by re-deposition of the component elements, with loss of oxygen from the surface becoming apparent when the etching parameters were changed as indicated. A relatively high carbon content measured by XPS is always observed on the plasma-etched mica surfaces for which a low silicon content is usually found. The reasons for this behaviour are discussed. The oxygen deficit observed on the argon plasma-etched mica surfaces may be even more significant if one makes allowance for the possible contribution that surface-adsorbed species containing oxygen can make to the oxygen signal.

Liu, Zhi Hui; Brown, Norman M. D.

1998-08-01

169

Atmospheric pressure streamer follows the turbulent argon air boundary in a MHz argon plasma jet investigated by OH-tracer PLIF spectroscopy  

NASA Astrophysics Data System (ADS)

An open question in the research of the dynamics of non-equilibrium cold atmospheric pressure plasma jets is the influence of ambient species on streamer propagation pathways. In the present work, by means of planar laser-induced fluorescence (PLIF), an atmospheric pressure argon plasma jet is investigated in a laminar and turbulent gas flow regime. The flow pattern is investigated with plasma on and plasma off. It is shown that in turbulent mode, the streamer path changes according to the flow pattern changes and the resulting changes in air abundance. From a comparison of an analytical diffusion calculation and LIF measurements, the air impurity boundary is determined. Most importantly, the origin of the streamer pathway is investigated in detail, by recording the flow pattern from OH-PLIF measurements and simultaneously measuring the streamer path by an overlay technique through emission measurements. It is shown that the streamer path is correlated to the turbulent flow pattern.

Iseni, S.; Schmidt-Bleker, A.; Winter, J.; Weltmann, K.-D.; Reuter, S.

2014-04-01

170

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

171

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

SciTech Connect

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

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

1989-04-01

172

Energy loss of argon in a laser-generated carbon plasma  

SciTech Connect

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

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

2010-02-15

173

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

174

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

175

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

PubMed

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

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

2000-07-10

176

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

NASA Astrophysics Data System (ADS)

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

Wu, Wei; Wang, Chuji

2012-10-01

177

Optical interface for a radially viewed inductively coupled argon plasma-Optical emission spectrometer  

US Patent & Trademark Office Database

The device disclosed herein is useful in the development of a new plasma spectrometer with enhanced sensitivity. An alteration in the configuration of the optic lenses used in conjunction with a water-cooled disc allows for the use of a short depth of focus to more reliably sample a given analyte. The collimating lens used in this invention can be placed within 4 millimeters of the load coil, including in the tip of the axial plasma generated by the RF generator. When used with in conjunction with a high-efficiency nebulizer to more precisely control the size of the sample droplets present in the base of the plasma further reduces the matrix effects seen in other spectrometers, while enhancing sensitivity. The optics configuration disclosed in the instant invention allows for the retrofitting of a conventional radially-viewed plasma spectrometer into a more sensitive axially-viewed spectrometer. The optics configuration can also be used to either enhance the sensitivity of existing spectrometers, or as a substitute for new ICP-OES systems to reduce their matrix effects as well. The typical spectrometer for which this change in configuration would be most useful would be an inductively coupled argon plasma-optical emission spectrometer (ICP-OES), in which the analyte studied can be sectioned axially.

2000-09-19

178

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

179

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

NASA Technical Reports Server (NTRS)

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 9500 K. The electron temperature values obtained have a range of uncertainty between -20% and +10% only. The electron temperature is equal or lower by approximately 1000 K in comparison to the heavy particle temperature (T2).

Schneider, C. P.; Exberger, R. J.

1978-01-01

180

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

PubMed Central

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

Yao, Chunyan; Qu, Ling; Fu, Weiling

2013-01-01

181

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

182

Plasma protein S residues 37-50 mediate its binding to factor Va and inhibition of blood coagulation.  

PubMed

Protein S (PS) is an anticoagulant plasma protein whose deficiency is associated with increased risk of venous thrombosis. PS directly inhibits thrombin generation by the blood coagulation pathways by several mechanisms, including by binding coagulation factors (F) Va and Xa. To identify PS sequences that mediate inhibition of FVa activity, antibodies and synthetic peptides based on PS sequence were prepared and employed in plasma coagulation assays, purified component prothrombinase assays, binding assays, and immunoblots. In the absence of activated protein C, monoclonal antibody (Mab) S4 shortened FXa-induced clotting in normal plasma but not in PS-depleted plasma. Mab S4 also blocked PS inhibition of FVa-dependent prothrombinase activity in purified component assays in the absence or presence of phospholipids and inhibited binding of PS to immobilised FVa. Epitope mapping identified N-terminal region residues 37-67 of PS as this antibody's epitope. A peptide representing PS residues 37-50 inhibited FVa-dependent prothrombinase activity in a non-competitive manner, with 50% inhibition observed at 11 µM peptide, whereas a peptide with a D-amino acid sequence of 37-50 was ineffective. FVa, but not FXa, bound specifically to the immobilised peptide representing residues 37-50, and the peptide inhibited binding of FVa to immobilised PS. These data implicate PS residues 37-50 as a binding site for FVa that mediates, at least in part, the direct inhibition of FVa-dependent procoagulant activity by PS. PMID:23892573

Heeb, Mary J; Mesters, Rolf M; Fernández, José A; Hackeng, Tilman M; Nakasone, Ryon K; Griffin, John H

2013-08-01

183

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

NASA Astrophysics Data System (ADS)

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 1020 m-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 1019 m-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.; Andrasch, M.; Ehlbeck, J.; Loffhagen, D.; Weltmann, K.-D.

2014-04-01

184

Time resolved optical emission spectroscopy of an inductively coupled plasma in argon and oxygen  

NASA Astrophysics Data System (ADS)

We present the space-time resolved excitation data for a single coil inductively coupled plasma (ICP) reactor operating in collision dominated regime in argon and oxygen at 13.56 MHz. Robot assisted scanning was used in order to obtain Abel inverted radial profiles of emission and subsequently of the net excitation rate as well as the number density of excited states. The net excitation rate in argon has modulation close to the walls due to the azimuthal field time dependence and a large bulk value independent of the time presumably due to low energy electron-metastable atom collisions. The time resolved profile in oxygen shows a much more pronounced modulation due to the azimuthal field and a much lower degree of excitation for the center of the tube. At low pressures a structure is observed in the temporal dependence of the net excitation rate that is consistent with two different mechanisms of electron acceleration with phase shift of ?/4: (I) by azimuthal field and (II) due to the drift motion in crossed electric and magnetic fields that leads to a motion in the azimuthal or radial direction and consequently to energy gain.

Tadokoro, Masahiro; Hirata, Hajime; Nakano, Nobuhiko; Petrovi?, Zoran Lj.; Makabe, Toshiaki

1998-01-01

185

Modeling the effect of dust on the plasma parameters in a dusty argon discharge under microgravity  

NASA Astrophysics Data System (ADS)

A dusty radio-frequency argon discharge is simulated with the use of a two-dimensional fluid model. In the model, discharge quantities, such as the fluxes, densities, and electric field are calculated self-consistently. The charge and density of the dust are calculated with an iterative method. During the transport of the dust, its charge is kept constant in time. The dust influences the electric potential distribution through its charge and the density of the plasma through recombination of positive ions and electrons on its surface. Results are presented for situations in which the dust significantly changes the discharge characteristics, both by a strong reduction of the electron density and by altering the electric potential by its charge. Simulations for dust particles having a radius of 7.5 ?m show that a double space charge layer is created around the sharp boundary of the dust crystal. A central dust-free region (void) is created by the ion drag force. Inside this void a strong increase of the production of argon metastables is found. This phenomenon is in agreement with experimental observations, where an enhanced light emission is seen inside the void.

Akdim, M. R.; Goedheer, W. J.

2003-06-01

186

Methyl-methacrylate bone cement surface does not promote platelet aggregation or plasma coagulation in vitro.  

PubMed

Leakage of viscous bone cement into venous blood possibly resulting in pulmonary embolism may occur during percutaneous vertebroplasty. Our aim was to study if bone cement surface or cement liquid component could induce platelet aggregation or plasma coagulation in vitro. Two types of commonly used methyl-methacrylate bone cement, Palacos (Heraeus Kulzer, Germany) and Vertebroplastic (DePuy, Acro Med, England), were smeared on thin glass slides that were inserted over the bottom of cuvettes immediately or after 24 h, and platelet aggregation was recorded over 10 min. Bone cement liquid component, containing methyl-methacrylate monomer and N,N-dimethyl-p-toluidine, was tested in 2% and 4% final concentration. Partial thromboplastin time (PTT) was determined by the hook method in the presence of bone cement-smeared glass slides or 6% bone cement liquid. Both types of bone cement, either fresh or aged, did not promote platelet aggregation, whereas collagen-coated glass slides induced substantial platelet aggregation (65 +/- 37%). On the other hand, bone cement liquids reduced platelet aggregation induced by collagen solution to an average of less than 15% (p < 0.01). Bone cement, fresh or aged, had no effect on PTT, but bone cement liquids significantly prolonged PTT: median and 1st-3rd interquartile range 149 (96-171) s for Vertebroplastic and 132 (99-194) s for Palacos, p = 0.03 for both comparisons with normal pool plasma without additives that had PTT of 69 (62-71) s. We conclude that the surface of fresh or aged bone cement is not thrombogenic in vitro. The bone cement liquid inhibits platelet aggregation and plasma clotting in relatively high concentrations that cannot be expected in vivo. PMID:15342214

Blinc, Ales; Bozic, Mojca; Vengust, Rok; Stegnar, Mojca

2004-01-01

187

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

National Technical Information Service (NTIS)

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

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

1984-01-01

188

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

189

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

SciTech Connect

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

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

1984-11-01

190

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

Microsoft Academic Search

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.

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

1982-01-01

191

Two-dimensional images of radiative and metastable excited state radial profiles for an inductively coupled plasma in argon  

Microsoft Academic Search

Inductively coupled plasma (ICP) was shown to be characterized by a substantial degree of stepwise excitation due to a large density of metastable atoms and an even larger population of electrons. The kinetics of metastables strongly affects the structure of the discharge and we have applied laser absorption spectroscopy to establish the density profile of argon metastables Ar(1s5) in a

Hajime Hirata; Masahiro Tadokoro; Nobuhiko Nakano; Z. Lj. Petrovic; T. Makabe

1999-01-01

192

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

193

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.

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

2014-01-01

194

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

195

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

NASA Astrophysics Data System (ADS)

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 minute (slm). With an increase in the H2O/Ar ratio from 0.0 to 1.9%, the plasma jet column length decreased from 11 mm to 4 mm, and the plasma jet became unstable when the ratio was higher than 1.9% elevation of plasma gas temperature up to 330 K was observed in the plasma temperature range of 420-910 K. Optical emission spectroscopy showed that the dominant plasma emissions changed from N2 in the pure Ar plasma jet to OH with the addition of water vapor, and simulations of emission spectra suggested non-Boltzmann distribution of the rotational levels in the OH A-state (v'=0). Spatially resolved absolute OH number densities along the plasma jet axis were measured using UV cavity ringdown spectroscopy of the OH (A-X) (0-0) band in the H2O/Ar ratio range of 0.0-1.9%. The highest OH number density is consistently located in the vicinity of the plasma jet tip, regardless of the H2O/Ar ratio. OH number density in the post-tip region follows approximately an exponential decay along the jet axis with the fastest decay constant of 3.0 mm in the H2O/Ar ratio of 1.5%. Given the low gas temperature of 420-910 K and low electron temperature of 0.5-5 eV along the jet axis, formation of the OH radical is predominantly due to electron impact induced dissociation of H2O and dissociative recombination of H2O+ resulting from the Penning ionization process.

Srivastava, Nimisha; Wang, Chuji

2011-09-01

196

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

197

Formation of silicon hydride using hyperthermal negative hydrogen ions (H ?) extracted from an argon-seeded hydrogen sheet plasma source  

Microsoft Academic Search

An E×B probe (a modified Wien filter) is constructed to function both as a mass spectrometer and ion implanter. The device, given the acronym EXBII selects negative hydrogen ions (H?) from a premixed 10% argon-seeded hydrogen sheet plasma. With a vacuum background of 1.0×10?6Torr, H? extraction ensues at a total gas feed of 1.8mTorr, 0.5A plasma discharge. The EXBII is

Marcedon S. Fernandez; Gene Q. Blantocas; Henry J. Ramos

2008-01-01

198

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

199

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

200

Effects of substrate bias and argon flux on the structure of titanium nitride films deposited by filtered cathodic arc plasma  

NASA Astrophysics Data System (ADS)

High-quality titanium nitride (TiN) films with nano-structure were prepared at ambient temperature on (111) silicon substrates by filtered cathodic arc plasma (FCAP) technology with an in-plane S filter. The effects of substrate bias and argon flux on the crystal grain size, roughness and preferred orientation were systematically investigated. It was found that the substrate bias and argon flux can affect the properties of TiN films effectively. Transmission electron microscope images showed that the crystal grain size was uniform and ranged from 10 nm to 5 nm. The results of X-ray diffraction and electron diffraction indicated that the degree of preferred orientation was more evident under high substrate bias and high argon flux.

Zhang, Y. J.; Yan, P. X.; Wu, Z. G.; Zhang, W. W.; Zhang, G. A.; Liu, W. M.; Xue, Q. J.

2005-01-01

201

Characterization of Modified Tapioca Starch in Atmospheric Argon Plasma under Diverse Humidity by FTIR Spectroscopy  

NASA Astrophysics Data System (ADS)

Tapioca is economical crop grown in Thailand and continues to be one of the major sources of starch. Nowadays, tapioca starch has been widely used in industrial applications, however the native form of starch has limited the applications. Thus scientists try to modify the properties of starch for increasing the stability of the granules, pastes to low pH, heat, and shear during the food process. We modify the tapioca starch by plasma treatment under an argon atmosphere. The degree of modification is determined by following water content in the starch granules. The tablet samples of native starch are also prepared and compared with the plasma treated starch. Before plasma treatment, the starch tablets are stored under three different relative humilities (RH) including 11%, 68%, and 78%RH, respectively. The samples are characterized using FTIR spectroscopy associated with the degree of cross-linking. The results show that the water molecules are engulfed into the starch structure in two ways, a tight bond and a weak absorption of water molecules which is represented at two wave number of 1630 cm-1 and 3272 cm-1, respectively. The degree of cross-linking can be identified from the relative intensity of these two peaks with the C—O—H peak at 993 cm-1. The results show that the degree of cross-linking increase in the plasma treated starch. The degree of cross-linking of the treated starch with high relative humidity is less than that of the treated starch with low relative humidity.

Deeyai, P.; Suphantharika, M.; Wongsagonsup, R.; Dangtip, S.

2013-01-01

202

Effects of MASP-1 of the Complement System on Activation of Coagulation Factors and Plasma Clot Formation  

PubMed Central

Background Numerous interactions between the coagulation and complement systems have been shown. Recently, links between coagulation and mannan-binding lectin-associated serine protease-1 (MASP-1) of the complement lectin pathway have been proposed. Our aim was to investigate MASP-1 activation of factor XIII (FXIII), fibrinogen, prothrombin, and thrombin-activatable fibrinolysis inhibitor (TAFI) in plasma-based systems, and to analyse effects of MASP-1 on plasma clot formation, structure and lysis. Methodology/Principal Findings We used a FXIII incorporation assay and specific assays to measure the activation products prothrombin fragment F1+2, fibrinopeptide A (FPA), and activated TAFI (TAFIa). Clot formation and lysis were assessed by turbidimetric assay. Clot structure was studied by scanning electron microscopy. MASP-1 activated FXIII and, contrary to thrombin, induced FXIII activity faster in the Val34 than the Leu34 variant. MASP-1-dependent generation of F1+2, FPA and TAFIa showed a dose-dependent response in normal citrated plasma (NCP), albeit MASP-1 was much less efficient than FXa or thrombin. MASP-1 activation of prothrombin and TAFI cleavage were confirmed in purified systems. No FPA generation was observed in prothrombin-depleted plasma. MASP-1 induced clot formation in NCP, affected clot structure, and prolonged clot lysis. Conclusions/Significance We show that MASP-1 interacts with plasma clot formation on different levels and influences fibrin structure. Although MASP-1-induced fibrin formation is thrombin-dependent, MASP-1 directly activates prothrombin, FXIII and TAFI. We suggest that MASP-1, in concerted action with other complement and coagulation proteins, may play a role in fibrin clot formation.

Hess, Katharina; Ajjan, Ramzi; Phoenix, Fladia; Dobo, Jozsef; Gal, Peter; Schroeder, Verena

2012-01-01

203

Electron Temperature and Ion Beam Scaling with RF Input Power in an Argon Helicon Plasma  

NASA Astrophysics Data System (ADS)

A flowing argon helicon plasma is formed in a 10 cm diameter, 1.5 m long Pyrex chamber with an axial magnetic field in nozzle or flat configuration, variable up to 1 kG in the source region. A new expansion chamber has been constructed and initial laser induced fluorescence (LIF) results including ion velocities and temperatures are presented. Microwave interferometry (105 GHz), collisional radiative spectroscopic codes and diamagnetic loops are used to measure electron density and temperature during pulsed (5 ms) RF operation. Calculated variation of the RF frequency (from 12 MHz to 15 MHz) during the pulse allows for low (<5%) reflected powers during the gas breakdown and the approach to and formation of the steady state plasma. The scaling of electron temperature with RF power is also examined for high (>3 kW) RF powers. The effect of different flow rates, magnetic field expansion variation and pressures are measured to observe the variation of the ion distribution function via LIF and the axial variation of acceleration due to neutral depletion. Possible double layer creation and sustainment in the downstream (relative to the RF antenna) transition to the expansion chamber is also examined at low flow rates and high RF powers.

Wiebold, Matt; Scharer, John; Sung, Yung-Ta

2010-11-01

204

Spectroscopic study of an expanded argon microwave (2.45 GHz) plasma at atmospheric pressure in a helium environment.  

PubMed

In the present work, an argon microwave (2.45 GHz) plasma flame created at the end of a surface-wave-sustained discharge column in a helium environment has been experimentally studied. This is a plasma with new possibilities because under some experimental conditions it expands, being less contracted than the plasma flame created in open air. The new expanded discharge could offer additional advantages for applications in which larger extensions of plasma were required. The expansion phenomenon of this plasma flame was studied under different experimental conditions. In every case, the characteristic parameters of this expanded plasma such as electron density, electron and gas temperatures, or density population of excited atomic levels were measured by using optical emission spectroscopic techniques. From these results, the main advantages of this plasma source were pointed out. PMID:19589221

García, M C; Varo, M; Martínez, P

2009-07-01

205

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.

Kim, Sung Chul; Cho, Ki Hong

2012-01-01

206

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

207

The Mechanisms of Coagulation.  

ERIC Educational Resources Information Center

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

Kurtz, Richard; Jesty, Jolyon

1994-01-01

208

Diagnostic by emission spectroscopy of an argon hydrogen RF inductive thermal plasma for purification of metallurgical grade silicon  

NASA Astrophysics Data System (ADS)

Purification of metallurgical grade silicon is one of the methods used to produce photovoltaic grade silicon. In our study, particles of metallurgical grade silicon were purified using a hydrogenated argon thermal plasma. During their residence time in the plasma, the particles were purified by partial evaporation and then sprayed into liquid droplets on the surface of a ceramic substrate. The in-flight purification of powder depends essentially on their evaporation rate, which is directly related to the temperature and chemical properties of the plasma zones crossed by the particles. It was, therefore, important to characterize the plasma parameters: electron density and temperature profiles. Excited states of atomic hydrogen, neutral and ionized silicon and impurity lines were detected in the plasma flow. Those lines were then used to estimate the electron density and temperature, which are around 2.4 × 1016 cm-3 and 10 500 K in the inductive zone. Finally, we estimate the silicon evaporated fraction X of the particles during their thermal treatment in the hydrogenated argon plasma. The results show that the loss of mass is weak (X = 2.5 × 10-4) but nevertheless sufficient for the elimination of the superficial impurities in the powders. This conclusion was confirmed by inductively coupled plasma analyses.

Benmansour, M.; Nikravech, M.; Morvan, D.; Amouroux, J.; Chapelle, J.

2004-11-01

209

Blood Coagulation Factor Activity in Endotoxemia.  

National Technical Information Service (NTIS)

Twelve dogs were subjected to endotoxemia and the activity of coagulation factors was studied quantitatively. Coagulation studies were performed on the dogs' normal plasma and on plasmas collected 5 minutes and 4 hours after endotoxin administration. All ...

R. L. West P. B. Jennings R. L. West

1966-01-01

210

Blood Coagulation Factor Activity in Experimental Endotoxemia.  

National Technical Information Service (NTIS)

Twelve dogs were subjected to endotoxemia and the activity of coagulation factors was studied quantitatively. Coagulation studies were performed on normal plasma and on plasma samples collected 5 minutes and 4 hours after endotoxin administration. All dog...

R. L. West M. J. Elovitz R. M. Hardaway

1965-01-01

211

Determination of cathode fall thickness in magnetized dc plasma for argon gas discharge  

NASA Astrophysics Data System (ADS)

The thickness of the cathode fall region (dc) in magnetized dc argon plasma has been investigated using two different methods, namely the axial potential distribution and the current density distribution along the glow discharge regions. The measurements have been carried out at the edge and center of the cathode surface. Dc (cold cathode) magnetron sputtering unit has been used. The radial and axial distributions of the magnetic field B, the Ia-Va characteristic curves of the glow discharge and the axial potential distribution and the current density distribution have been investigated. The thickness of the cathode fall region was between 2 and 3.3 mm for the two methods in pressure (P) range of 0.53-4 mbar. It is concluded that a noticeable reduction of the cathode fall thickness (about 33%) has been found in the presence of a magnetic field and at the center of the cathode and stronger electric field at the edge of the cathode fall, and hence high rates of sputtering are expected.

Rida Galaly, Ahmed; Elakshar, F. F.

2013-12-01

212

Determination of inorganic contaminants in glue by inductively coupled argon plasma optical emission spectrometry.  

PubMed

A closed vessel method using a microwave oven was developed for the determination of As, B, Ba, Bi, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, Sn and Sb by Inductively Coupled Argon Plasma Optical Emission Spectrometry (ICP OES). The method was applied to samples of polyvinyl acetate-based glue in water emulsions. Parameters such as wavelength, nebulization pressure and RF power were optimized and the residual acidity after the digestion process was determined. The addition of internal standards was evaluated and the accuracy of the proposed method was verified with addition and recovery experiments and also with certified reference materials, achieving good results. Using a nebulization flow rate of 0.73 L min(-1)and a RF power of 1200 W it was possible to obtain adequate values for limit of detection and limit of quantification as well as recovery values in the range of 80-106%, for all the analytes. The analysis of coloured glue samples (white, black, blue, yellow, red and green), widely used by children, showed no contamination by the elements studied. PMID:21376954

Matoso, Erika; Cadore, Solange

2011-04-15

213

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

SciTech Connect

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 a typical solvent (1% HNO/sub 3/ in H/sub 2/O) consists mainly of ArH/sup +/, Ar/sup +/, H/sub 3/O/sup +/, H/sub 2/O/sup +/, NO/sup +/, O/sub 2//sup +/, HO/sup +/, Ar/sub 2//sup +/, Ar/sub 2/H/sup +/, and Ar/sup 2 +/. The mass spectra of the trace elements studied consist principally of singly charged monatomic (M/sup +/) or oxide (MO/sup +/) ions in the correct relative isotopic abundances. Analytical calibration curves obtained in an integration mode show a working range covering nearly 4 orders of magnitude with detection limits of 0.002 to 0.06 ..mu..g/mL for those elements studied. This approach offers a direct means of performing trace elemental and isotopic determinations on solutions by mass spectrometry.

Houk, R.S. (Iowa State Univ., Ames); Fassel, V.A.; Flesch, G.D.; Svec, H.J.; Gray, A.L.; Taylor, C.E.

1980-12-01

214

Formation of silicon hydride using hyperthermal negative hydrogen ions (H-) extracted from an argon-seeded hydrogen sheet plasma source  

Microsoft Academic Search

An E × B probe (a modified Wien filter) is constructed to function both as a mass spectrometer and ion implanter. The device, given the acronym EXBII selects negative hydrogen ions (H-) from a premixed 10% argon-seeded hydrogen sheet plasma. With a vacuum background of 1.0 × 10-6 Torr, H- extraction ensues at a total gas feed of 1.8 mTorr,

Marcedon S. Fernandez; Gene Q. Blantocas; Henry J. Ramos

2008-01-01

215

Beneficial effects of microwave-induced argon plasma treatment on cellular behaviors of articular chondrocytes onto nanofibrous silk fibroin mesh  

Microsoft Academic Search

Silk fibroin scaffolds were examined as a biomaterial option for tissue-engineered cartilage-like tissue. In tissue engineering\\u000a for cartilage repair using a scaffold, initial chondrocyte-material interactions are important for the following cell behaviors.\\u000a In this study, the surface of nanofibrous silk fibroin (NSF) meshes was modified by a microwave-induced argon plasma treatment\\u000a in order to improve the cytocompatibility of the meshes

Soo Chang Jin; Hyun Sook Baek; Yeon I Woo; Mi Hee Lee; Jung-Sung Kim; Jong-Chul Park; Young Hwan Park; Dong Kyun Rah; Kie-Hyung Chung; Seung Jin Lee; In Ho Han

2009-01-01

216

Argon plasma exposure enhanced intermixing in an undoped InGaAsP/InP quantum-well structure  

NASA Astrophysics Data System (ADS)

Intermixing in an undoped InGaAsP/InP quantum well structure enhanced by near-surface defects generated using inductively coupled argon plasma is temperature dependent. The group III sublattice interdiffusion can be four times as fast as that of the group V sublattice for the annealing temperature lower than 600 °C, and a maximum band gap redshift of 50 nm is obtained in experiment. Blueshift is obtained at 700 °C when the group V sublattice interdiffusion becomes appreciable.

Nie, D.; Mei, T.; Tang, X. H.; Chin, M. K.; Djie, H. S.; Wang, Y. X.

2006-08-01

217

Behavior of the 398.4nm Hg II Spectral Line in the Helium and Argon Plasmas  

NASA Astrophysics Data System (ADS)

The astrophysically important 398.4 nm Hg II spectral line was investigated in the laboratory helium and argon plasmas. The mercury atoms were sputtered from the amalgamated gold cylindrical plates located in the homogenous part of the pulsed discharge. We have found that strong intensity of the 398.4 nm Hg II line is due to excessively high density of the helium metastable atoms.

Skocic, M.; Burger, M.; Gavrilov, M.; Bukvic, S.; Djenize, S.

2012-12-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

219

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

220

Randomized placebo-controlled human pilot study of cold atmospheric argon plasma on skin graft donor sites.  

PubMed

Cold atmospheric plasma has already been shown to decrease the bacterial load in chronic wounds. However, until now it is not yet known if plasma treatment can also improve wound healing. We aimed to assess the impact of cold atmospheric argon plasma on the process of donor site healing. Forty patients with skin graft donor sites on the upper leg were enrolled in our study. The wound sites were divided into two equally sized areas that were randomly assigned to receive either plasma treatment or placebo (argon gas) for 2 minutes. Donor site healing was evaluated independently by two blinded dermatologists, who compared the wound areas with regard to reepithelialization, blood crusts, fibrin layers, and wound surroundings. From the second treatment day onwards, donor site wound areas treated with plasma (n = 34) showed significantly improved healing compared with placebo-treated areas (day 1, p = 0.25; day 2, p = 0.011; day 3, p < 0.001; day 4, p < 0.001; day 5, p = 0.004; day 6, p = 0.008; day 7, p = 0.031). Positive effects were observed in terms of improved reepithelialization and fewer fibrin layers and blood crusts, whereas wound surroundings were always normal, independent of the type of treatment. Wound infection did not occur in any of the patients, and no relevant side effects were observed. Both types of treatment were well tolerated. The mechanisms contributing to these clinically observed effects should be further investigated. PMID:23937657

Heinlin, Julia; Zimmermann, Julia L; Zeman, Florian; Bunk, Wolfram; Isbary, Georg; Landthaler, Michael; Maisch, Tim; Monetti, Roberto; Morfill, Gregor; Shimizu, Tetsuji; Steinbauer, Julia; Stolz, Wilhelm; Karrer, Sigrid

2013-01-01

221

Amplification of femtosecond vacuum ultraviolet laser pulses at 126 nm in an optical-field-induced ionized argon plasma  

NASA Astrophysics Data System (ADS)

Short-wavelength lasers in the vacuum ultraviolet (VUV) spectral region between 100 and 200 nm have not yet been developed to the same degree as visible and infrared lasers. We have been developing the argon excimer laser at 126 nm by using an optical-field-induced ionized (OFI) argon plasma. We have observed the gain of 0.86 /cm at 126 nm in the OFI Ar plasma, which was produced inside a hollow fiber with a diameter of 250 microns and a length of 5 cm. In this paper, we have used the OFI plasma gain medium as an amplifier of the 126 nm radiation. A femtosecond 126 nm pulse was produced by the seventh-order nonlinear wavelength conversion of a femtosecond Ti:sapphire laser at 882 nm. The femtosecond wavelength-converted coherent VUV beam was then injected inside the OFI plasma that was produced by the same Ti:sapphire laser, resulting in a 2.4-fold increase of the VUV intensity with one-pass amplification. The gain-length product of 0.87 with the one-pass amplification was evaluated, which was consistent with the value we have observed in the previous measurements. The further extension of the OFI plasma by using a hollow fiber would be plausible to increase the gain-length product and the VUV amplified intensity.

Kubodera, Shoichi; Kaku, Masanori; Katto, Masahito; Miyazaki, Kenzo

2012-10-01

222

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

NASA Astrophysics Data System (ADS)

We report continuous wave cavity ring down spectroscopy (CW-CRDS) measurements of ion velocity distribution functions (VDFs) in low pressure argon helicon plasma (magnetic field strength of 600 G, Te ~ 4 eV and n ~ 5 × 1011 cm-3). Laser induced fluorescence (LIF) is routinely used to measure VDFs of argon ions, argon neutrals, helium neutrals, and xenon ions in helicon sources. Here, we describe a CW-CRDS diagnostic based on a narrow line width, tunable diode laser as an alternative technique to measure VDFs in similar regimes but where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopic technique; CW-CRDS can also provide a direct quantitative measurement of the absolute metastable state density. The proof of principle CW-CRDS measurements presented here are of the Doppler broadened absorption spectrum of Ar II at 668.6138 nm. Extrapolating from these initial measurements, it is expected that this diagnostic is suitable for neutrals and ions in plasmas ranging in density from 1 × 109 cm-3 to 1 × 1013 cm-3 and target species temperatures less than 20 eV.

Chakraborty Thakur, Saikat; McCarren, Dustin; Carr, Jerry; Scime, Earl E.

2012-02-01

223

Continuous wave cavity ring down spectroscopy measurements of velocity distribution functions of argon ions in a helicon plasma.  

PubMed

We report continuous wave cavity ring down spectroscopy (CW-CRDS) measurements of ion velocity distribution functions (VDFs) in low pressure argon helicon plasma (magnetic field strength of 600 G, T(e) ? 4 eV and n ? 5 × 10(11) cm(-3)). Laser induced fluorescence (LIF) is routinely used to measure VDFs of argon ions, argon neutrals, helium neutrals, and xenon ions in helicon sources. Here, we describe a CW-CRDS diagnostic based on a narrow line width, tunable diode laser as an alternative technique to measure VDFs in similar regimes but where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopic technique; CW-CRDS can also provide a direct quantitative measurement of the absolute metastable state density. The proof of principle CW-CRDS measurements presented here are of the Doppler broadened absorption spectrum of Ar II at 668.6138 nm. Extrapolating from these initial measurements, it is expected that this diagnostic is suitable for neutrals and ions in plasmas ranging in density from 1 × 10(9) cm(-3) to 1 × 10(13) cm(-3) and target species temperatures less than 20 eV. PMID:22380092

Chakraborty Thakur, Saikat; McCarren, Dustin; Carr, Jerry; Scime, Earl E

2012-02-01

224

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

SciTech Connect

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

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

2008-03-19

225

Analysis of inductively coupled argon plasma-enhanced quantum-well intermixing process for multiple bandgap implementation  

NASA Astrophysics Data System (ADS)

The inductively coupled argon (Ar) plasma-enhanced quantum-well intermixing has been investigated for the implementation of multiple bandgaps in an InGaAs/InGaAsP quantum-well laser structure. Multiple bandgap control is achieved by controlling the local defect concentrations without manipulating the critical rapid thermal annealing process using a multi-step plasma exposure or a spatial defect modulation. The interdiffusion process is found to obey Fick's law and enhanced by the near-surface point defects after a short plasma exposure time. For a prolonged exposure, the enhancement is reduced attributed to the possible formation of defect clusters. With single-step plasma exposure, the defect concentrations, thus intermixing degree, can be controlled using a variable window opening. This work demonstrates the practical approaches of multiple bandgap creation suitable for the photonic-integrated circuit application.

Nie, D.; Mei, T.; Djie, H. S.; Chin, M. K.; Tang, X. H.; Wang, Y. X.

2006-02-01

226

A new blood coagulation inhibitor from the snake Bothrops jararaca plasma: isolation and characterization.  

PubMed

A novel thrombin inhibitor, Bothrops jararaca inhibitor (BjI), has been identified and purified from B. jararaca snake blood by two anionic chromatographic steps. Purified BjI showed two polypeptide chains with molecular masses of 109 and 138 kDa, by SDS-PAGE in reducing conditions. On the other hand, in nonreducing conditions the molecular masses were 150 and 219 kDa, suggesting that the polypeptide chain 109 kDa can be a dimer form linked by disulfide bond. However, the native BjI shows a molecular mass higher than 1000 kDa by gel filtration chromatography, indicating the need of a quaternary structure formation for the blood coagulation inhibition. BjI is a specific thrombin coagulant activity inhibitor that does not affect other thrombin functions, such as: amidolytic and platelet aggregation activities. BjI is not an antithrombin-like inhibitor. Fibrinogen and heparin competition ELISA assays with BjI and thrombin showed that fibrinogen does not interfere in the BjI and thrombin binding, however, heparin interferes in BjI and thrombin interaction, suggesting that BjI binds to heparin site or other sites close to it. Our findings indicate that BjI is an exosite binding thrombin inhibitor, specific upon coagulant activity thrombin inhibitor, without any anti-platelet aggregation activity. PMID:12927776

Tanaka-Azevedo, Anita M; Tanaka, Aparecida S; Sano-Martins, Ida S

2003-09-01

227

Quantification of water and plasma diagnosis for electrothermal vaporization–inductively coupled plasma–mass spectrometry: the use of argon and argide polyatomics as probing species  

Microsoft Academic Search

The water content of the carrier flow originating from an electrothermal vaporization unit (ETV) attached to an inductively coupled plasma mass spectrometer was monitored by following the argon hydride ion (ArH+) at m\\/z=37. The goal was to measure the water expelled by the ETV at sample vaporization and evaluate the influence of this parameter on the ion-generation efficiency. Linear responses

Jean-François Alary; Eric D. Salin

1998-01-01

228

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

229

Three-dimensional flow dynamics of an argon RF plasma with dc jet assistance: a numerical study  

NASA Astrophysics Data System (ADS)

Time-dependent three-dimensional numerical simulation based on a large-eddy simulation approach is conducted to ascertain the complicated thermofluid dynamics of an argon radio-frequency (RF) inductively coupled plasma with a direct-current (dc) plasma jet assistance, considering non-uniform densities and properties in time and space as well as turbulence generation and suppression. Using a combination of numerical schemes suitable to capture vortices, the present simulation successfully shows unsteady behaviour of the plasma as well as wave-like interfaces between a high-temperature flow and a low-temperature flow as a result of the balance of fluid-dynamical instability and a viscous diffusion effect. Small cold vortices generated near a dc jet injector are entrained into and merged with vortices generated around the dc jet. Subsequently, they interact with large vortices in an RF induction coil region, which causes a much more complex vortex structure.

Shigeta, Masaya

2013-01-01

230

Application of a wall-stabilized argon plasma arc for the determination of some volatile hydride-forming elements  

NASA Astrophysics Data System (ADS)

Volatile hydrides of As, Se, Sb and Sn, produced by a continuous manifold hydride generator, have been swept with argon and injected into the plasma of home-made direct current wall-stabilized argon plasma arc via one of its stabilizing segments. The arc burns in argon with an arc current of 20 A and a cathode-anode voltage of 40 V. Measurements were carried out using a 1 m focal length computer-controlled monochromator (Jobin Yvon 1000R) equipped with a holographic grating having 2400 grooves mm - 1 . Optimal values of the experimental variables that give the highest value of intensity ratio of line-to-background were determined. These are: plasma gas flow rate 1.0 l min - 1 , carrier gas flow rate 0.35 l min - 1 for As and Sb and 0.6 l min - 1 for Se and Sn, concentration of nitric acid used for acidification of the sample 2 M for As and Sb, 0.5 M for Se and 0.1 M for Sn and sodium borohydride concentration: 1.5% for As and Se and 2% for Sb and Sn. Chemical interference of some transition elements that affect the hydride generation process and a trial to mask their interference effect were investigated. Calibration curves were linear and limits of detection calculated on the base of 3 ? of the background were found to be as low as 3.9, 6.8, 9.8 and 13.2 ng ml - 1 for As, Se, Sb and Sn, respectively. Finally, the analytical applicability of the arc device was tested by the determination of As in four lake sediment samples, LKSD 1, LKSD 2, LKSD 3 and LKSD 4, of the Centre for Mineral and Energy Technology, Ottawa, Ontario, Canada, which have been analyzed for As using atomic absorption spectrometry (AAS). The results were in good agreement with those obtained by AAS.

Eid, M. A.; Moustafa, H. R.; Al Ashkar, E. A.; Ali, S. S.

2006-04-01

231

Emission characteristics of pulse-periodic barrier-discharge plasma in a mixture of krypton with argon and liquid freon vapor  

NASA Astrophysics Data System (ADS)

Radiation of a nanosecond barrier discharge in a mixture of krypton, argon, and carbon-tetrachloride vapor is studied in the spectral range of 150-300 nm. The plasma radiation spectra and the dependences of the intensities of the 258 nm Cl2( D' ? A'), 222 nm KrCl( B ? X), and 175 nm ArCl( B ? X) bands on the partial pressure of liquid freon vapor, argon, and krypton, as well as on the discharge excitation conditions, are studied. The optimal compositions of gas mixtures for creating a broadband UV-VUV emitter based on the band system of argon chloride, krypton chloride, and chlorine molecule are determined.

Shuaibov, A. K.; Minya, A. I.; Gritsak, R. V.; Gomoki, Z. T.

2014-02-01

232

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

NASA Astrophysics Data System (ADS)

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; Shneider, Mikhail N.; Alexeenko, Alina A.

2014-06-01

233

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.

234

Argon mini-arc meets its match: use of a laser-driven plasma source in ultraviolet-detector calibrations.  

PubMed

The National Institute of Standards and Technology operates two spectral comparator facilities, both of which are used to provide detector calibrations from the ultraviolet to the near-infrared spectral range. One, the Ultraviolet Spectral Comparator Facility (UV SCF), has been in operation for more than two decades, providing one of the core calibration services. Recently, the illumination source used in the UV SCF has been changed from an argon mini-arc source to a laser-driven plasma light source. This new source has higher brightness, a smaller source size, better temporal stability, and much better conversion efficiency than the previous source. The improvements in the capabilities are summarized. PMID:24663306

Arp, Uwe; Vest, Robert; Houston, Jeanne; Lucatorto, Thomas

2014-02-20

235

Soft X-ray optimization studies on a dense plasma focus device operated in neon and argon in repetitive mode  

Microsoft Academic Search

This paper investigates the emission characteristics of a\\u000a high-performance low-energy (3-kJ) repetitive dense plasma focus device,\\u000a NX2, operated at up to 1-Hz repetition rate to develop it as an intense\\u000a source of soft X-rays (SXR) for microlithography and micromachining.\\u000a Various SXR yield optimization studies with argon and neon as filling\\u000a gases were performed under different operating conditions (charging\\u000a voltage, filling

D. Wong; A. Patran; T. L. Tan; R. S. Rawat; P. Lee

2004-01-01

236

Effects of EDTA on routine and specialized coagulation testing and an easy method to distinguish EDTA-treated from citrated plasma samples.  

PubMed

Coagulation testing is performed with citrate-treated plasma. Samples submitted in other anticoagulants, such as EDTA, should not be tested. We aimed to evaluate the effects of EDTA on routine and specialized coagulation tests and to establish sodium tetraphenylborate testing as a quick and reliable method to identify EDTA-treated plasma samples. We performed the following measurements on citrateand EDTA-treated plasma samples from 10 healthy volunteers: sodium tetraphenylborate testing, prothrombin time (PT), partial thromboplastin time (PTT), potassium concentration, and functional assays for factors II, V, VII, VIII, IX, X, XI, XII, proteins C and S, and antithrombin. Mean values for citrate- and EDTA-treated plasma were most different for PT, PTT, factors V and VIII, and proteins C and S. Sodium tetraphenylborate testing correctly classified 100% of citratetreated and EDTA-treated samples. We confirm that EDTA has effects on coagulation assays. Sodium tetraphenylborate testing is a quick, simple, and inexpensive method for coagulation laboratories to identify samples erroneously submitted in EDTA. PMID:19923105

Crist, Ronda A; Gibbs, Kathie; Rodgers, George M; Smock, Kristi J

2009-01-01

237

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.

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

2010-01-01

238

Numerical studies on velocity, temperature history and heat transfer to the particles injected into the argon plasma  

NASA Astrophysics Data System (ADS)

A new approach to study the particle velocity in a thermal plasma in relation to input parameters (power, gas flow rate, injection velocity of the particle and particle size) and nozzle dimensions (nozzle length and diameter) has been made. Injected particle's temperature and thermal history were calculated for particles of three different materials (alumina, tungsten and graphite) in argon plasma. Allowable powder feed rate was calculated for the particles. Heat transfer per particle injected in to the plasma is reported. Liquid fraction of the particle after it reached the melting point is also reported. Particle velocity is found to increase with increase in power, gas flow rate and injection velocity and decrease with increase in particle size, nozzle length and nozzle diameter. Thermal histories of the particles in relation to the plasma temperature and particle diameter are presented. Particle's residence time is found to increase with increase in diameter of the particle. Allowable powder feed rate for complete melting of the particle is higher at higher percentage utilisation of the plasma power. Powder feed rate is seen to decrease with increase in particle size and it is higher for tungsten and lower for graphite particle. Heat transfer rate from plasma to particle is seen to decrease with increase in time and the same is higher for plasmas of higher temperature and smaller sized particle.

Ramasamy, R.; Selvarajan, V.

2001-08-01

239

Retention of Coagulation Factors in Plasma Frozen after Extended Holding at 1–6°C  

Microsoft Academic Search

Background and Objectives: The ability to use plasma, isolated from units of whole blood and frozen within 24 h of phlebotomy, as a substitute for plasma frozen within 8 h of phlebotomy would have several advantages for blood centers. It should provide increased flexibility pertaining to the freezing of plasma for clinical use. We have conducted studies to assess the

Janis F. Smith; Paul M. Ness; Gary Moroff; Naomi L. C. Luban

2000-01-01

240

Low-temperature atmospheric pressure argon plasma treatment and hybrid laser-plasma ablation of barite crown and heavy flint glass.  

PubMed

We report on atmospheric pressure argon plasma-based surface treatment and hybrid laser-plasma ablation of barite crown glass N-BaK4 and heavy flint glass SF5. By pure plasma treatment, a significant surface smoothing, as well as an increase in both the surface energy and the strength of the investigated glass surfaces, was achieved. It was shown that for both glasses, hybrid laser plasma ablation allows an increase in the ablation depth by a factor of 2.1 with respect to pure laser ablation. The ablated volume was increased by an averaged factor of 1.5 for N-BaK4 and 3.7 for SF5. PMID:22695664

Gerhard, Christoph; Roux, Sophie; Brückner, Stephan; Wieneke, Stephan; Viöl, Wolfgang

2012-06-10

241

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

242

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

243

Optical emission spectroscopy diagnostics of inductively-driven plasmas in argon gas at low pressures  

Microsoft Academic Search

An optical emission spectroscopy method for determination of electron temperature, electron density and gas temperature is developed and applied for diagnostics of inductively-driven argon discharges in a cylindrical geometry. The discharges are maintained at frequency 27 MHz, applied power varied in the limits P=(90 – 160) W and gas pressure in the range p=(1.1 – 117.3) Pa. The method combines measurements of

S. Iordanova; I. Koleva

2007-01-01

244

Diagnostics and Computational Modeling of Argon, Helium, and Deuterium Helicon Plasmas in Nonuniform Magnetic Fields  

Microsoft Academic Search

Summary form only given. Radiofrequency helicon waves are excited in argon, helium, and deuterium at a frequency of 13.56 MHz with input RF powers of up to 2.5 kW using a half-turn double helix antenna. The effect on radial density profiles and ionization efficiency due to nonuniform axial static magnetic field profiles is investigated, with peak magnetic fields of up

C. Mark Denning; John E. Scharer

2005-01-01

245

Interferometric investigation of the influence of argon buffer gas on the characteristics of laser-induced aluminum plasmas.  

PubMed

An interferometric analysis was performed to investigate the influence of argon (Ar) buffer gas on the characteristics of laser-induced aluminum (Al) plasma at atmospheric pressure. The plasma was produced by focusing a Q-switched Nd:YAG laser pulse (?=1064??nm, pulse duration ?5??ns, E=6.0??mJ) onto an Al target. The interference patterns were constructed using a Nomarski interferometer incorporated with a frequency-doubled, Q-switched Nd:YAG laser (?=532??nm, pulse duration ?10??ns) that generates an interferometric probe beam. The interferometric measurements were carried out as a function of the elapsed time after the onset of breakdown under the conditions of open air and an Ar gas jet flow (5??l/min). With the injection of an Ar buffer gas jet in the ablation process, an increase in electron density and a preferential axial plasma expansion of the plasma plume were observed during the early stages of plasma formation as a consequence of increased inverse-Bremsstrahlung (IB) absorption efficiency. PMID:24921120

Oh, Seong Y; Singh, Jagdish P; Lim, Changhwan

2014-06-10

246

Experimental deduction of isentropic exponent for ion and electron in high density argon plasma  

Microsoft Academic Search

Summary form only given. The isentropic exponent for plasma was deduced from measurements of electron temperature, Te, and ion temperature, Ti, in terms of plasma density, np, with the assumptions of linear characteristics of plasma parameters on discharge parameter in LaB6 dc plasma. The isentropic exponent for electron, gammae, is estimated by 1.06 with isentropic relation (P = Cngamma), and

H.-J. Woo; K.-S. Chung; T. Lho; M.-J. Lee

2009-01-01

247

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

248

Genetic studies of low-abundance human plasma proteins. X. Coagulation factor XIIIB variants in blacks.  

PubMed

Human coagulation factor XIIIV (F XIIIB) demonstrates genetically determined-structural variation with three common and several rare alleles. Population genetics studies reveal enormous intra and interracial group variation. In the present study, using isoelectric focusing and immunoblotting, we have determined for the first time the polymorphic occurrence of F XIIIB allelic forms in a native African population, namely Nigerian Blacks. In addition, F XIIIB data have been extended to various US Black populations. The characteristic feature of the black gene pool is the relative high frequency of the F XIIIB*2 allele, the highest being in Nigerians (0.723). The F XIIIB*6 allele is present at a polymorphic level in both the US and Nigerian Blacks and appears to be a unique black allele marker. The present technique has demonstrated several new alleles designated: F XIIIB*18, FXIIIB*22, F XIIIB*23 and F XIIIB*24. Among these new alleles the F XIIIB*23 exists at polymorphic level in both the US and Nigerian Blacks and is another unique Black allele marker of potential significance in population genetics studies. PMID:2714240

Kamboh, M I; Ferrell, R E

1989-01-01

249

Electron impact excitation cross sections for argon of interest in plasma modeling  

Microsoft Academic Search

We have applied the relativistic distorted-wave (RDW) method to calculate electron impact excitation cross sections for a number of fine-structure transitions in argon atoms. These include excitation from the ground state to the 3p53d, 3p54d and 3p55s fine-structure levels, from the non-metastable levels of the 3p54s configuration to all ten fine-structure levels of the 3p54p configuration as well as from

R. K. Gangwar; L. Sharma; R. Srivastava; A. D. Stauffer

2009-01-01

250

Cytomegalovirus DNA stability in EDTA Anti-Coagulated Whole Blood and Plasma Samples  

PubMed Central

Background Cytomegalovirus (CMV) DNA viral load testing is routinely performed in centers that serve patients that are immunosuppressed from organ or hematopoietic stem cell transplantation. Clinical laboratories that offer this testing often face practical concerns about the storage of these specimens to ensure accurate measurement for patient care. The studies published that look at CMV DNA stability at 4°C have done so only up to 72 hours. Objective Our objective was to determine the stability of CMV DNA in whole blood and plasma for clinical viral load testing over a 14 day period. Study Design Twenty-one plasma samples that were CMV-positive and twenty whole blood samples (including eleven CMV-negative whole blood samples spiked with CMV-positive plasma) were stored at 4°C and underwent extraction and amplification at 3 time points: Day 0, Day 7, and Day 14. Results Log10 values were calculated and t-test was performed on the values comparing Day 0 to Day 14 for plasma and whole blood. There was no statistically significant difference between Day 0 and Day 14 for both specimen types, including the CMV-negative whole blood that was spiked with CMV-positive plasma. Conclusions CMV DNA in plasma and whole blood is stable for 14 days at a temperature of 4°C.

Abdul-Ali, Deborah; Kraft, Colleen S.; Ingersoll, Jessica; Frempong, Mona

2011-01-01

251

Double layer-like structures in the core of an argon helicon plasma source with uniform magnetic fields  

NASA Astrophysics Data System (ADS)

A hot (Te ? 10 eV) electron population is observed in the core of a 3 mTorr argon helicon plasma source at 500 W RF power and 900 G uniform axial magnetic field strength, 12 cm from the edge of the helicon antenna. A double layer-like structure consisting of a localized axial electric field of approximately 8 V/cm over 1-2 cm is observed adjacent to the hot electron population. The potential step generated by the electric field is shown to be large enough to trap the hot electrons. To our knowledge this is the first observation of these structures in the core of a helicon discharge.

Umair Siddiqui, M.; Hershkowitz, Noah

2014-02-01

252

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

253

Measurement of the Time-Dependent Distribution of Ionization States in an Argon Plasma from a Mach-10 Jet: Final Report.  

National Technical Information Service (NTIS)

Results from experiments designed to measure the time-dependent distribution of ionization states in an argon plasma produced by laser irradiation of a high-Mach-number gas jet are presented. The gas valve/nozzle target system was designed for nominal Mac...

P. C. Filbert T. R. Fisher D. Kohler J. D. Perez R. A. Walton

1988-01-01

254

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

SciTech Connect

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

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

2010-10-15

255

Experimental Studies on Electric Currents Flowing into the Hollow Dug on the Substrate Surface in an Argon Plasma  

NASA Astrophysics Data System (ADS)

The studies on the electric currents flowing into the hollow are of crucial importance for plasma etching. In this work, the sheath structures and the currents flowing into the hollow are measured by using a hollow probe, which consists of an envelope forming a hollow and of a collector movable along the axis. Here, we assume the envelope a substrate. An argon plasma was produced by hot cathode discharge. The typical plasma parameters are Te = 1.5 eV, and ne = 1.2 × 10^+7 cm-3. The inner diameters D of the hollows were 1 mm (smaller compared to the Debye length ?) and 3.0 mm (comparable to ?). Results obtained in the case of the D ~= 3 mmID envelope are as follows: (1) At collector potential Vp is equal to Vwall, the Ven-Ip curves (en: envelope, Ip: the collector current) are sensitive to the location d of the collector. (2) At the sufficiently deep point d=-15 mm, only electrons flow into the collector.

Arikata, I.; Konishi, K.; Kubota, T.

1998-10-01

256

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

257

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

258

Measurement of plasma-surface energy fluxes in an argon rf-discharge by means of calorimetric probes and fluorescent microparticles  

SciTech Connect

Measured energy influx densities toward a tungsten dummy substrate in an argon rf-plasma are presented and a model for the description of the energy influx density based on plasma parameters, which have been obtained by Langmuir probe measurements, is applied. Furthermore, temperature measurements of microparticles are presented, which are confined in the plasma sheath. An extension of the model is developed for the description of the energy influx density to the particles. The comparison of model and experimental results offer the possibility to obtain an improved understanding of plasma-surface interactions.

Maurer, H. R.; Kersten, H. [Institute for Experimental and Applied Physics, Christian-Albrechts-University, 24098 Kiel (Germany); Hannemann, M.; Basner, R. [INP Greifswald e.V., Felix-Hausdorff-Strasse 2, 17489 Greifswald (Germany)

2010-11-15

259

Time-dependent 3D simulation of an argon RF inductively coupled thermal plasma  

NASA Astrophysics Data System (ADS)

A time-dependent 3D numerical simulation using a large eddy simulation approach is conducted to meet the first challenge in revealing the coherent vortex structure and dynamic behaviours of the thermofluid field in a radio-frequency inductively coupled thermal plasma torch. The high-temperature plasma region exhibits unsteady behaviour near the coil. At the same time, the high- and low-temperature flows form undulating interfaces. The flow field has a complicated 3D structure with a recirculating zone due to Lorentz forces. Because of the recirculating flow, the injected cold gas tends to avoid the high-temperature plasma region. The largest vortex structure, at approximately 10?000 K, remains in the plasma region, whereas small cold eddies are generated near the top wall of the torch and transported downstream, avoiding the plasma region. In the intermediate-temperature regions around the plasma, relatively large vortices are repeatedly born and dissolve, connecting with and separating from each other. Most of them have non-uniform temperatures because they are easily generated in the interfacial regions with temperature gradients around a thermal plasma flow. The time scale of the transport of cold eddies is much smaller than that of the dynamic motion of the high-temperature plasma region.

Shigeta, Masaya

2012-10-01

260

Temperature and Radiation Distriubution of Horizontally Opposed Argon Twin Torch Plasma Arc  

Microsoft Academic Search

Summary form only given. Plasma arc heating has the following outstanding features compared with combustion heating such as the high temperature, high energy density and little exhaust gas. Therefore, it is applied to dissolution, refinement, temperature adjustment of melting steel et al. In addition, the applying plasma arc heating technology, which can make the volume reduction and harmless processing of

K. Iwase; T. Iwao; M. Yumoto; S. Tashiro; M. Tanaka

2007-01-01

261

Initial stages in hundreds of Joules plasma focus operating in deuterium – argon mixtures: Preliminary results  

NASA Astrophysics Data System (ADS)

In plasma focus research, the mixture of deuterium with noble gases has been one of the attempts for both improving the radiation yield and for understanding of the origin of the fusion reactions. However, differences on the neutron emission from the plasma focus operating with gas mixtures according to the device energy have been reported. In an attempt to improve the understanding of such experimental observations, experiments in a very low energy plasma focus device (400J) working with gas mixtures are presented. Different stages prior to the final compression of the plasma focus discharges were studied; such as the breakdown phase and the plasma sheath movement. The electrical signals analysis shows differences on the breakdown voltage but similar axial sheath velocities. Nonetheless, these preliminary observations must be corroborated with additional experimental data.

Veloso, Felipe; Soto, Leopoldo; Pavez, Cristian; Moreno, José

2014-05-01

262

Argon-dominated plasma beam generated by filtered vacuum arc and its substrate etching  

NASA Astrophysics Data System (ADS)

A new technique to etch a substrate as a pre-treatment prior to functional film deposition was developed using a filtered vacuum arc plasma. An Ar-dominated plasma beam was generated from filtered carbon arc plasma by introducing appropriate flow rate of Ar gas in a T-shape filtered arc deposition (T-FAD) system. The radiation spectra emitted from the filtered plasma beam in front of a substrate table were measured. The substrate was etched by the Ar-dominated plasma beam. The principal results are summarized as follows. At a high flow rate of Ar gas (50 ml/min), when the bias was applied to the substrate, the plasma was attracted toward the substrate table and the substrate was well etched without film formation on the substrate. Super hard alloy (WC), bearing steel (SUJ2), and Si wafer were etched by the Ar-dominated plasma beam. The etching rate was dependent on the kind of substrate. The roughness of the substrate increased, when the etching rate was high. A pulse bias etched the substrate without roughening the substrate surface excessively.

Tanoue, Hideto; Kamiya, Masao; Oke, Shinichiro; Suda, Yoshiyuki; Takikawa, Hirofumi; Hasegawa, Yushi; Taki, Makoto; Kumagai, Masao; Kano, Makoto; Ishikawa, Takeshi; Yasui, Haruyuki

2009-06-01

263

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

264

Effect of argon and hydrogen on deposition of silicon from tetrochlrosilane in cold plasmas  

NASA Technical Reports Server (NTRS)

The roles of Ar and H2 on the decomposition of SiCl4 in cold plasma were investigated by Langmuir probes and mass spectrometry. Decomposition of the reactant by Ar only has been found to be very slow. In presence of H2 in the plasma SiCl4 is decomposed by fast radical-molecule reactions which are further enhanced by Ar due to additional ion-molecule reactions in which more H radicals are produced. A model for the plasma-surface interactions during deposition of mu-Si in the Ar + H2 + SiCl4 system is presented.

Manory, R. R.; d.

1985-01-01

265

Semen-coagulating protein, SVS2, in mouse seminal plasma controls sperm fertility.  

PubMed

Mammalian seminal plasma is known to contain a decapacitation factor(s) that prevents capacitation and thus, the fertility of sperm. This phenomenon has been observed in experiments conducted in vitro that assessed the inhibition of epididymal sperm fertility by seminal plasma or by the purified decapacitation factor. However, the phenomenon of decapacitation has not yet been characterized in vivo. In the present study, we demonstrate that seminal vesicle protein secretion 2 (SVS2), which is a 40-kDa basic protein and a major component of the copulatory plug, enters the uterus and interacts with ejaculated sperm heads after copulation. The SVS2-binding region of sperm changed from the postacrosomal region to the equatorial segment, while the sperm migrated through the uterus and finally disappeared in the oviduct. Furthermore, SVS2 reduced the fertility of epididymal sperm. The sperm treated with SVS2 decreased the percentage of fertilized oocytes from 60% to 10%. The capacitation state was assessed by protein tyrosine phosphorylation and the comprehensiveness of the acrosome reaction. SVS2 functioned to maintain sperm in the uncapacitated state and to reverse capacitated sperm to the uncapacitated state. We found that the fertility of ejaculated sperm is associated with SVS2 distribution in the female reproductive tract. These results indicate that SVS2 functions as a decapacitation factor for mouse sperm. PMID:17123940

Kawano, Natsuko; Yoshida, Manabu

2007-03-01

266

Immunoblotting studies of coagulation factor XII, plasma prekallikrein, and high molecular weight kininogen  

SciTech Connect

Immunoblotting techniques for the qualitative and quantitative analysis of FXII, PK, and HMWK in whole plasma are presented. Sensitive, specific, and quantitative immunodetection of FXII and PK can be achieved by developing the blots with polyclonal antiserum followed by radiolabeled FXII or PK, respectively. This approach is based on the assumption that bivalent antibodies bind monovalently to the NC-bound antigen and have available binding sites to bind radiolabeled antigen derived from the fluid phase. This radiolabeled antigen overlay principle may be generally useful for immunodetection of any trace protein in complex mixtures, provided that the radiolabeled purified antigen is available. Immunoblotting may also be helpful for the partial characterization of the structural or functional abnormalities of CRM-positive variant molecules. For example, earlier studies of a FXII-variant molecule that had been purified and characterized were supported by immunoblotting studies of the CRM-positive deficient plasma. Quantitative measurement of HMWK is possible using a monoclonal antibody directed against the light chain of HMWK followed by radiolabeled secondary antibody. Quantitation of cleaved and single-chain HMWK is possible using dilutions of dextran sulfate-activated NHP on unreduced SDS-PAGE and dilutions of unactivated NHP with reduced SDS-PAGE as standards. These assays allow assessment of the degree of in vivo activation of the contact system in various disease states.

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

1987-01-01

267

Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment  

SciTech Connect

This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H{sub {alpha}} and the H{sub {beta}} lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A. [Department of Electrical Engineering, University of Bologna, Viale Risorgimento 2, 40136 Bologna (Italy)

2012-08-01

268

Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment  

NASA Astrophysics Data System (ADS)

This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H? and the H? lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

2012-08-01

269

Numerical simulation study on fluid dynamics of plasma window using argon  

NASA Astrophysics Data System (ADS)

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.; Hershcovitch, A.; Yang, L.; Zhang, X. Y.; Wei, G. D.

2013-07-01

270

Production of high quality syngas from argon/water plasma gasification of biomass and waste.  

PubMed

Extremely hot thermal plasma was used for the gasification of biomass (spruce sawdust, wood pellets) and waste (waste plastics, pyrolysis oil). The plasma was produced by a plasma torch with DC electric arc using unique hybrid stabilization. The torch input power of 100-110 kW and the mass flow rate of the gasified materials of tens kg/h was set up during experiments. Produced synthetic gas featured very high content of hydrogen and carbon monoxide (together approximately 90%) that is in a good agreement with theory. High quality of the produced gas is given by extreme parameters of used plasma--composition, very high temperature and low mass flow rate. PMID:24148259

Hlina, M; Hrabovsky, M; Kavka, T; Konrad, M

2014-01-01

271

Surface modification of low-density polyethylene by inductively coupled argon plasma.  

PubMed

The surface chemistry and nanotopography of low-density polyethylene (LDPE) were modified by downstream, inductively coupled, radio frequency (rf) Ar plasma without inducing surface damage. The extent of surface modification was controlled by the applied ion energy fluence, determined from the plasma ion density measured with a Langmuir probe. The treated LDPE surfaces were characterized by atomic force microscope (AFM) imaging, contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Analysis of AFM surface images confirmed that topography changes occurred at the nanoscale and that surface damage was insignificant. Contact angle measurements demonstrated an enhancement of the surface hydrophilicity with the increase of the plasma power. XPS results showed surface chemistry changes involving the development of different carbon-oxygen functionalities that increased the surface hydrophilicity. Physical and chemical surface modification was achieved under conditions conducive to high-density inductively coupled rf plasma. PMID:16853255

Tajima, S; Komvopoulos, K

2005-09-22

272

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

273

In situ absolute air, O3 and NO densities in the effluent of a cold RF argon atmospheric pressure plasma jet obtained by molecular beam mass spectrometry  

NASA Astrophysics Data System (ADS)

A molecular beam mass spectrometer has been calibrated and used to measure the air entrainment, nitric oxide and ozone concentrations in the effluent of a cold atmospheric pressure argon RF driven plasma jet. The approaches for calibrating the mass spectrometer for different species are described in detail. Gas phase densities of ozone and nitric oxide up to 7.5 ppm and 4 ppm, respectively, have been measured in the far effluent of the argon plasma jet. The difference in air entrainment when the plasma is undisturbed or is close to a well, which is the case for e.g. in vitro plasma–cell interaction studies, is shown. In addition, an exponential decay of the positive ion flux as a function of distance in the effluent is obtained. Furthermore, the effect of plasma power, duty cycle and air and O2 admixtures introduced into the argon flow on the NO and O3 production is presented, including the possibility of independent control of the NO and O3 flux from the jet.

van Ham, B. T. J.; Hofmann, S.; Brandenburg, R.; Bruggeman, P. J.

2014-06-01

274

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

SciTech Connect

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

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

2010-05-15

275

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

276

Inferring argon plasma properties from optical emission: the role of metastable atoms  

NASA Astrophysics Data System (ADS)

Collisions between electrons and Ar atoms are primarily responsible for the characteristic plasma glow of Ar discharges. The intensity of a given emission line depends upon both the electron energy distribution (EED) and the excitation cross sections for populating the excited levels. Since the EED also drives the plasma chemistry, there is a need for non-invasive diagnostics of the EED in plasmas for industrial processing. One obstacle in using optical emission spectroscopy (OES) of the plasma glow as a diagnostic is that only electrons in the highest energy range of the EED have enough energy to excite atoms directly from the Ar 3p^6 ground state. Due to the much lower energy threshold, and much larger cross sections, excitation from atoms in 3p^44s metastable levels can contribute substantially to plasma emissions. Recent measurements of excitation cross sections into 3p^55p levels (?: 395-470 nm) from the Ar metastable levels [1] allow us to exploit the role of metastable atoms to probe the low energy range of the EED. Verification of this OES technique with simultaneous Langmuir probe (for the EED) and optical absorption (for the metastable density) measurements is underway. [1] R. O. Jung, et al, Phys. Rev. A 75, 052707 (2007). *-1ex

Jung, R. O.; Boffard, John B.; Lin, Chun C.; Ding, R.; Ting, Y.-H.; Yang, Y.; Wendt, A. E.

2007-10-01

277

Local thermodynamic equilibrium modeling of ionization of impurities in argon inductively coupled plasma  

NASA Astrophysics Data System (ADS)

Essentially higher ionization degree of small concentrations of elements in inductively coupled plasma in comparison to the ionization of pure elements is emphasized. This conclusion is used to determine the relative dependence of the sensitivity of the inductively coupled plasma mass spectrometer on the atomic mass. The possibility of evaluation of the ionization temperature and electron density from mass spectrometric signals is proposed. Temperatures about 7000 K and 8000 K were obtained from the ionization ratio dependences on ionization potentials. Electron densities of the order of magnitude 10 15 cm - 3 , in excess to the local thermodynamic equilibrium values, follow from the application of the Saha equation to the measurement results and indicate the recombining character of the plasma in the mass spectrometer measurement region. Effects due to additional ionization from matrix were discussed. The effect is largest on minor abundant ionization state components. Matrix effect is restricted to some temperature interval, which depends on the whole matrix composition and the plasma state. The results show that the local thermodynamic equilibrium modeling, if adequately matching the sample composition, can be useful as a quantitative basis for both description of the plasma state and indication of the character of the nonequilibrium effects.

Serapinas, Petras; Šalkauskas, Julius; Ežerinskis, Žilvinas; Acus, Art?ras

2010-01-01

278

Ontogenetic variation of metalloproteinases and plasma coagulant activity in venoms of wild Bothrops atrox specimens from Amazonian rain forest.  

PubMed

A comparative study of venoms from juvenile, sub-adult and adult wild Bothrops atrox specimens captured in Manaus region (Brazil) was performed. All venoms tested had acidic pH (5.5) and the human plasma coagulant activity was higher in venoms from juvenile and sub-adult specimens than in adults. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the most intense bands in adult venoms corresponded to polypeptides of 23 and 50kDa. The 23kDa protein was not detected in juvenile venoms. The 23 and 50kDa proteins were purified by two steps of reversed phase-HPLC followed by size exclusion HPLC. Partial amino acid sequence of the 23kDa protein showed homology to metalloproteinases from other snake venoms. Electrospray ionization mass spectrometric analysis (ESI-MS) showed that the 23kDa band contained at least three isoforms of 23030, 23300 and 23645Da. The 50kDa polypeptide was N-terminally blocked for Edman degradation and presented molecular masses ranging from 46.8 to 49.4kDa by ESI-MS. Both proteins were detected by anti-mutalysin II antibodies in immunoblotting assay indicating that they belong to the metalloproteinase family. Immunoblotting analysis also showed that the 23kDa band increased in intensity from juvenile to adult specimens.SDS-PAGE analysis of juvenile and adult venoms following autoproteolysis in pH 7.4 suggested that endogenous venom metalloproteinases can digest the 50kDa metalloproteinase, originating a new protein band of 27kDa. It was also demonstrated in juvenile venoms that the 23kDa band was not the result of proteolytic processing of the 50kDa metalloproteinase. PMID:12076654

López-Lozano, Jorge Luis; de Sousa, Marcelo Valle; Ricart, Carlos André O; Chávez-Olortegui, Carlos; Flores Sanchez, Eladio; Muniz, Emiro G; Bührnheim, Paulo F; Morhy, Lauro

2002-07-01

279

Entrainaient and demixing in subsonic argon\\/helium thermal plasma jets  

Microsoft Academic Search

The velocity, temperature, entrained air fraction, and Ar\\/He concentration profiles were measured in a subsonic thermal plasma jet using an enthalpy probe and mass spectrometer. Through interaction with the surrounding atmosphere, air is quickly entrained into the jet, resulting in rapidly decreasing velocities and temperatures. Due to the difference in ionization potential, a significant diffusive separation or demixing of Ar

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

1993-01-01

280

X-ray Emission from Argon Plasma Focus Contaminated with Copper Impurities in AECS PF-2 Using Five Channel Diode Spectrometer  

NASA Astrophysics Data System (ADS)

In this work, the X-ray ratio method using different thicknesses of Al foil absorbers was used to study the influence of copper impurities on the electron temperature determination of the focused plasma in AECS PF-2 with argon filling gas. Five channels of BPX 65 PIN diodes were employed to record the X-ray pulses generated by a low energy Mather type plasma focus device energized by a 25 ?F, 15 kV (2.8 kJ) capacitor bank consisting of two capacitors each with 12.5 ?F capacity connected in parallel. By comparing the ratio values experimentally obtained for a series of shots at various pressures with theoretically calculated ratios for argon plasma, the X-ray emission ratio was found to correspond to the Cu-K? line radiation for most of the discharges and only about less than 10% of the measurements give the correct expected electron temperature of 1.5-2.5 keV for the focused argon plasma.

Al-Hawat, Sh.; Akel, M.; Wong, C. S.

2011-12-01

281

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

282

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

NASA Astrophysics Data System (ADS)

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; Hassanein, Ahmed

2014-04-01

283

Entrainaient and demixing in subsonic argon\\/helium thermal plasma jets  

Microsoft Academic Search

The velocity, temperature, entrained air fraction, and Ar\\/He concentration profiles were measured in a subsonic thermal plasma\\u000a jet using an enthalpy probe and mass spectrometer. Through interaction with the surrounding atmosphere, air is quickly entrained\\u000a into the jet, resulting in rapidly decreasing velocities and temperatures. Due to the difference in ionization potential,\\u000a a significant diffusive separation or demixing of Ar

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

1993-01-01

284

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

285

A differentially pumped argon plasma in the linear plasma generator Magnum-PSI: gas flow and dynamics of the ionized fraction  

NASA Astrophysics Data System (ADS)

Magnum-PSI is a linear plasma generator designed to reach the plasma-surface interaction (PSI) regime of ITER and nuclear fusion reactors beyond ITER. To reach this regime, the influx of cold neutrals from the source must be significantly lower than the plasma flux reaching the target. This is achieved by a differential pumping scheme, where the vacuum vessel is divided by skimmers into separate chambers which are individually pumped. The non-magnetized expansion of 5 Pa m3 s-1 (3 slm) argon in a low background pressure was studied in the differentially pumped vacuum vessel fitted with non-cooled flat skimmers. The behavior of the neutral component was studied with direct simulation Monte Carlo simulations and Rayleigh scattering measurements. Thomson scattering and double Langmuir probe measurements were performed on the ionized fraction. It was found that the electrons and neutral particles are not completely coupled in the shock front. The neutral fraction shows clear signs of invasion from hotter background gas, causing the average temperature and density to increase before the shock. This is also shown in the ionization ratio, which has been determined in front of and behind the first skimmer. This study helps us to understand the behavior of the gas flow in the machine and validates our modeling.

van Eck, H. J. N.; Hansen, T. A. R.; Kleyn, A. W.; van der Meiden, H. J.; Schram, D. C.; Zeijlmans van Emmichoven, P. A.

2011-08-01

286

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

287

Characteristics of copper\\/carbon and nickel\\/carbon composite films produced by microwave plasma-assisted deposition techniques from argon–methane gas mixtures  

Microsoft Academic Search

Copper\\/hydrogenated amorphous carbon (a-C:H) and nickel\\/a-C:H composite films have been deposited on Si substrates by combining sputter-deposition of metal and microwave plasma-assisted chemical vapor deposition of carbon from argon–methane mixtures of various concentrations. The deposition rate of films was found to vary between 10 and 25 nm\\/min depending on the CH4 concentration in the gas phase. The crystallographic structure of

Y. Pauleau; F. Thièry; L. Latrasse; S. N. Dub

2004-01-01

288

Formation of silicon hydride using hyperthermal negative hydrogen ions (H -) extracted from an argon-seeded hydrogen sheet plasma source  

NASA Astrophysics Data System (ADS)

An E × B probe (a modified Wien filter) is constructed to function both as a mass spectrometer and ion implanter. The device, given the acronym EXBII selects negative hydrogen ions (H -) from a premixed 10% argon-seeded hydrogen sheet plasma. With a vacuum background of 1.0 × 10 -6 Torr, H - extraction ensues at a total gas feed of 1.8 mTorr, 0.5 A plasma discharge. The EXBII is positioned 3 cm distance from the sheet core as this is the region densely populated by cold electrons ( Te ˜ 2 eV, Ne ˜ 3.4 × 10 11 cm -3) best suited for H - formation. The extracted H - ions of flux density ˜0.26 A/m 2 are segregated, accelerated to hyperthermal range (<100 eV) and subsequently deposited into a palladium-coated 1.1 × 1.1 cm 2, n-type Si (1 0 0) substrate held at the rear end of the EXBII, placed in lieu of its Faraday cup. The palladium membrane plays the role of a catalyst initiating the reaction between Si atoms and H - ions simultaneously capping the sample from oxidation and other undesirable adsorbents. AFM and FTIR characterization tests confirm the formation of SiH 2. Absorbance peaks between 900-970 cm -1 (bending modes) and 2050-2260 cm -1 (stretching modes) are observed in the FTIR spectra of the processed samples. It is found that varying hydrogen exposure time results in the shifting of wavenumbers which may be interpreted as changes in the frequencies of vibration for SiH 2. These are manifestations of chemical changes accompanying alterations in the force constant of the molecule. The sample with longer exposure time exhibits an additional peak at 2036 cm -1 which are hydrides of nano-crystalline silicon.

Fernandez, Marcedon S.; Blantocas, Gene Q.; Ramos, Henry J.

2008-12-01

289

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

290

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

SciTech Connect

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

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

1994-05-01

291

Measurement of the time-dependent distribution of ionization states in an argon plasma from a Mach-10 jet: Final report  

SciTech Connect

Results from experiments designed to measure the time-dependent distribution of ionization states in an argon plasma produced by laser irradiation of a high-Mach-number gas jet are presented. The gas valve/nozzle target system was designed for nominal Mach-10 performance and produced a jet of neutral gas several centimeters long from a nozzle exit of 1.5 mm diameter. The jet was irradiated at a position having an approximate atomic density of 1 /times/ 10/sup 18//cm/sup 3/ by 500 J of 351-nm laser light with a pulse width of 600 ps at the NLUF's OMEGA laser facility. It was found necessary to pre-ionize the gas in order to couple-in sufficient laser energy to produce a plasma. An argon plasma was then created that was dominated by charge states of Ar VIII through Ar XI. Comparison with a theoretical model which solved the time-dependent rate equations indicates that a plasma temperature of approximately 70 eV was achieved. A subsequent development effort carried out at the Lockheed Palo Alto Research Laboratory (LPARL) to improve the gas jet target system is also described. This work indicated that by increasing the pressure in the valve by a factor of 5 increased the coupling to the laser and produced significantly larger signals and higher plasma temperatures. 7 refs., 21 figs., 1 tab.

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

1988-09-28

292

Measurement of Stark width of some Ar I transitions and the investigation of local thermodynamic equilibrium (LTE) in an atmospheric d. c. argon plasma jet  

SciTech Connect

The Stark widths of seven Ar I transitions are reported. Axial line shape data from an atmospheric d.c. argon plasma jet were Abel-inverted to obtain radial line shapes. The electron-density was determined by Stark width measurements of the hydrogen H{sub {beta}} transition. In the electron-density region of {le}6 {times} 10{sup 22} m{sup {minus}3} the experimental Ar I Stark widths are fitted to a linear dependence on the electron-density. Values of Stark width extrapolated to other electron densities are compared to measurements reported in the literature on the 4s-4p array. Experimental values are up to 45% smaller than those predicted by Griem's theory of Stark broadening. Conditions for local thermodynamic equilibrium (LTE) to exist in an atmospheric argon plasma jet were studied. The experiment measures the emission coefficient of seven Ar I transitions and the line shape of the hydrogen H{sub beta} transition. After transforming the side-on data into radial space the excited neutral argon atom-density and the electron-density are determined. It is found LTE does not exist below an electron-density of 6 {times} 10{sup 33} m{sup {minus}3} in the experimental conditions.

Bakshi, V.

1988-01-01

293

Spectroscopic Investigations of Glow Discharges and the Emissions of Nonmetallic Elements in the Argon Inductively Coupled Plasma.  

NASA Astrophysics Data System (ADS)

Spectroscopic investigations have been carried out on hollow cathode discharges adapted from laser technology for use as a spectroscopic light source and the argon inductively coupled plasma (ICP) as an excitation source for nonmetal emission. High and low voltage aluminum and copper hollow cathode discharges were studied as a source of ionic and resonant atomic metal emission. The high voltage versions achieve strongly positive current-voltage behavior through utilization of the obstructed discharge phenomenon. The current-pressure-intensity-voltage relationships for low and high voltage copper hollow cathode discharges were studied with the inert gases He, Ne, Ar, Kr, and Xe. The intensity for copper resonant atomic emission with the fill gases Ar, Kr, and Xe improved relative to neon in the high voltage lamp when compared to the low voltage lamp. Absorption measurements through the cathode bore show the ground state atom density to increase with the atomic weight of the fill gas at any given level of intensity, at the fill gas pressure yielding highest resonant atomic copper emission. The estimated ion/atom intensity ratio is increased with fill gases which have metastable or ionization energies greater than the excitation energy of the ion transition. A copper hollow cathode lamp incorporating a short positive column discharge in front of the cathode opening was investigated for its lineshape as measured spectroscopically and by its atomic absorption sensitivity. Incorporation of this positive column allowed higher intensities to be obtained at the same line quality as a commercial hollow cathode lamp. An enlarged cathode volume also improves the lineshape at a given intensity. Inductively coupled plasma spectra for the elements C, O, N, Cl, P, S, and Br were obtained in the vacuum ultraviolet utilizing a vacuum polychromator and SWR film. The detection limit for injected O_2 and N _2 detected electronically by the VUV emissions is 1.3 and 0.9 micrograms respectively with this system. A VUV filter photometer was utilized for oxygen and phosphorus analysis. The detection limit for injected oxygen was 1 microgram with this photometer; the detection limit for phosphorus as inorganic phosphate in aqueous solution is 10^{-3} M. The bandpass of the photometer limits its selectivity.

Phillips, Hugh Alan

1988-12-01

294

Performance of coagulation tests in patients on therapeutic doses of rivaroxaban. A cross-sectional pharmacodynamic study based on peak and trough plasma levels.  

PubMed

Knowledge of anticoagulation status during rivaroxaban therapy is desirable in certain clinical situations. It was the study objective to determine coagulation tests most useful for assessing rivaroxaban's anticoagulant effect. Peak and trough blood samples from 29 patients taking rivaroxaban 20 mg daily were collected. Mass spectrometry and various coagulation assays were performed. "On-therapy range" was defined as the rivaroxaban concentrations determined by LC-MS/MS. A "misprediction percentage" was calculated based on how often results of each coagulation assay were in the normal reference range, while the rivaroxaban concentration was in the "on-therapy" range. The on-therapy range was 8.9 - 660 ng/ml. The misprediction percentages for prothrombin time (PT) and activated partial thromboplastin time (aPTT), using multiple reagents and coagulometers, ranged from 10% - 52% and 31% - 59%, respectively. PT, aPTT and activated clotting time (ACT) were insensitive to trough rivaroxaban: 59%, 62%, and 80% of samples had a normal result, respectively. Over 95% of PT and ACT values were elevated at peak. Four different rivaroxaban calibrated anti-Xa assays had R² values >0.98, demonstrating strong correlations with rivaroxaban drug levels. In conclusion, PT, aPTT and ACT are often normal in patients on therapeutic doses of rivaroxaban. However, PT and ACT may have clinical utility at higher drug plasma levels. Rivaroxaban calibrated anti-factor Xa assays can accurately identify low and high on-therapy rivaroxaban drug levels and, therefore, have superior utility in all clinical situations where assessment of anticoagulation status may be beneficial. PMID:24401946

Francart, S J; Hawes, E M; Deal, A M; Adcock, D M; Gosselin, R; Jeanneret, C; Friedman, K D; Moll, S

2014-06-01

295

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

297

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.

Diamond, Scott L.

2013-01-01

298

Systems biology of coagulation.  

PubMed

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, modeling 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 mobilization or inside-out signaling, 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, S L

2013-06-01

299

Enhanced chondrogenic responses of human articular chondrocytes onto silk fibroin/wool keratose scaffolds treated with microwave-induced argon plasma.  

PubMed

Silk fibroin (SF) is a natural, degradable, fibrous protein that is biocompatible, is easily processed, and possesses unique mechanical properties. Another natural material, wool keratose (WK), is a soluble derivative of wool keratin, containing amino acid sequences that induce cell adhesion. Here, we blended SF and WK to improve the poor electrospinability of WK and increase the adhesiveness of SF. We hypothesized that microwave-induced argon plasma treatment would improve chondrogenic cell growth and cartilage-specific extracellular matrix formation on a three-dimensional SF/WK scaffold. After argon plasma treatment, static water contact angle measurement revealed increased hydrophilicity of the SF/WK scaffold, and scanning electron microscopy showed that treated SF/WK scaffolds had deeper and more cylindrical pores than nontreated scaffolds. Attachment and proliferation of neonatal human knee articular chondrocytes on treated SF/WK scaffolds increased significantly, followed by increased glycosaminoglycan synthesis. Our results suggest that microwave-induced, plasma-treated SF/WK scaffolds have potential in cartilage tissue engineering. PMID:20633153

Cheon, Young Woo; Lee, Won Jai; Baek, Hyun Sook; Lee, Young Dae; Park, Jong-Chul; Park, Young Hwan; Ki, Chang Seok; Chung, Kie-Hyung; Rah, Dong Kyun

2010-05-01

300

A Comparison of Laser Induced Florescence and Continuous Wave Ring Down Spectroscopy Measurements of Argon Ion and Neutral VDFs in a Helicon Plasma  

NASA Astrophysics Data System (ADS)

In this work, we compare two spectroscopic methods for measuring the velocity distribution functions (VDFs) of argon ions and neutrals in a helicon plasma: laser induced florescence (LIF) and continuous wave cavity ring down spectroscopy (CW-CRDS). An established and powerful technique, LIF suffers from the requirement that the initial state of the LIF sequence have a substantial density. In most cases, this requirement limits LIF to ions and atoms with large metastable state densities for the given plasma conditions. CW-CRDS is considerably more sensitive than LIF and can potentially be applied to much lower density populations of ion and atom states. However, CRDS is a line integrated technique that lacks the spatial resolution of LIF. CRDS is a proven, ultra-sensitive, cavity enhanced absorption spectroscopy technique and when combined with a CW diode laser that has a sufficiently narrow linewidth, the Doppler broadened absorption line, i.e., the VDFs, can be measured. We present CW-CRDS and LIF measurements of the VDFs in an argon plasma using the 668.614 nm (in vacuum) line of Ar II and the 667.9125 nm (in vacuum) line of Ar I.

McCarren, Dustin; Vandervort, Robert; Carr, Jerry, Jr.; Scime, Earl

2012-10-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

302

Feed gas humidity introduced into a MHz atmospheric pressure argon plasma jet affects plasma-generated species and plasma-treated human skin cells  

NASA Astrophysics Data System (ADS)

It is known, that gas humidity is an important parameter in plasma treatment of biological systems under ambient conditions. However, humidity in the feed gas of an atmospheric pressure plasma jet is even more crucial than ambient humidity since humid working gas is transported through the active plasma zone and the water molecules become dissociated. The so produced oxygen/hydrogen species are significant for the active plasma component composition. In this work the effect of feed gas humidity on the plasma, on plasma-treated cell growth medium (RPMI) and subsequently on human skin cells is investigated. It is shown, that already small concentrations of humidity (<1000 ppm) induce changes in the optical emission spectrum of the effluent, increase H2O2 concentration in liquid cell growth medium and inhibit human skin cell proliferation.

Winter, Jörn; Wende, Kristian; Hammer, Malte U.; Tresp, Helena; Iseni, Sylvain; Dünnbier, Mario; Masur, Kai; Weltmann, Klaus-Dieter; Reuter, Stephan

2012-10-01

303

Surface modification of poly(3,4-ethylene dioxthiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films by atmospheric-pressure argon plasma for organic thin-film solar cells.  

PubMed

Highly-conductive poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films obtained by the addition of dimethylsulfoxide (DMSO) and the argon plasma exposure were used as a transparent conductive anode (TCA) for copper-phthalocyanine (CuPc)/C60 organic thin-film solar cells (OSCs). The CuPc/C60 OSCs on as-grown DMSO added PEDOT:PSS layer showed a power efficiency of 0.6%, whereas it was improved markedly to 1.34% after the atmospheric-pressure argon plasma exposure, which was comparable to that formed on indium-tin-oxide layer. Effects of the DMSO addition and the argon plasma exposure in the spin-coated PEDOT:PSS films is demonstrated in terms of the in-depth characterization of optical and electrical properties. PMID:22097525

Ino, Tomohisa; Hayashi, Tatsuya; Fukuda, Takeshi; Ueno, Keiji; Shirai, Hajime

2011-09-01

304

Deviation from Boltzmann distribution in excited energy levels of singly-ionized iron in an argon glow discharge plasma for atomic emission spectrometry  

NASA Astrophysics Data System (ADS)

A Boltzmann plot for many iron ionic lines having excitation energies of 4.7-9.1 eV was investigated in an argon glow discharge plasma when the discharge parameters, such as the voltage/current and the gas pressure, were varied. A Grimm-style radiation source was employed in a DC voltage range of 400-800 V at argon pressures of 400-930 Pa. The plot did not follow a linear relationship over a wide range of the excitation energy, but it yielded a normal Boltzmann distribution in the range of 4.7-5.8 eV and a large overpopulation in higher-lying excitation levels of iron ion. A probable reason for this phenomenon is that excitations for higher excited energy levels of iron ion would be predominantly caused by non-thermal collisions with argon species, the internal energy of which is received by iron atoms for the ionization. Particular intense ionic lines, which gave a maximum peak of the Boltzmann plot, were observed at an excitation energy of ca. 7.7 eV. They were the Fe II 257.297-nm and the Fe II 258.111-nm lines, derived from the 3d54s4p 6P excited levels. The 3d54s4p 6P excited levels can be highly populated through a resonance charge transfer from the ground state of argon ion, because of good matching in the excitation energy as well as the conservation of the total spin before and after the collision. An enhancement factor of the emission intensity for various Fe II lines could be obtained from a deviation from the normal Boltzmann plot, which comprised the emission lines of 4.7-5.8 eV. It would roughly correspond to a contribution of the charge transfer excitation to the excited levels of iron ion, suggesting that the charge-transfer collision could elevate the number density of the corresponding excited levels by a factor of ca.104. The Boltzmann plots give important information on the reason why a variety of iron ionic lines can be emitted from glow discharge plasmas.

Zhang, Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki

2012-01-01

305

GaN Etch Rates Compared with Atomic Chlorine Density and Ion Flux in an Argon/Chlorine Inductively Coupled Plasma  

NASA Astrophysics Data System (ADS)

We present GaN etch rates (maximum 700nm/min), atomic chlorine densities (via Laser Induced Fluorescence at 200W RF power), positive ion densities (Langmuir probe) and positive ion wall flux (capacitive planar probe) using an Inductively Coupled Plasma as a function of chlorine in argon gas fraction from 0% to 100% at maximum RF power and pressure of 400 W and 20 mTorr respectively. In general, with chlorine addition, etch rates rise initially then tend to saturate at fractions above 50% Cl_2. Wall flux and n^+ approximate the inverse of this behaviour. The atomic chlorine density at 200W RF power rises monotonically with a pronounced inflection near 50% Cl_2. The positive ion wall flux - atomic chlorine density product strongly correlates with etch rate suggesting physical etching dominates below 50% Cl2 and chemical processes above. This is reflected in changes of the Ga/N surface stoichiometry, determined by XPS analysis.

Mahony, C. M. O.; Rizvi, S. A.; Maguire, P. D.; Garcia, F.; Graham, W. G.

2004-09-01

306

Temporally and spectrally resolved observation of a crossed-flow DBD plasma jet using pure helium and argon/acetone mixed gases  

NASA Astrophysics Data System (ADS)

A crossed gas flow dielectric barrier discharge plasma jet using vertical pure helium and tilted argon/acetone mixed gases is investigated in this study, mainly by an intensified charge-coupled device (ICCD) camera. We have observed ionization-front propagation and transient glow discharge formation following the rise of the applied voltage pulse. A secondary discharge with a reverse polarity was ignited during the falling slope of the applied voltage pulse. In order to analyze excited-species distribution inside the discharge, optical interference filters were placed in front of the ICCD camera with the center wavelengths set at the excited species' transition. The imaging results revealed detailed discharge structures around the crossing point of the two gas flows including bridging emission between the two flows that changed position with time. We also discuss the ignition mechanisms of the secondary discharge considering effects of accumulated charge during the primary discharge and changes in the channel conductivity following the primary discharge.

Urabe, Keiichiro; Sands, Brian L.; Ganguly, Biswa N.; Sakai, Osamu

2012-06-01

307

Coagulation in Estuaries.  

National Technical Information Service (NTIS)

The coagulation rates of kaolinite, illite, and montmorillonite were determined in solutions at various ionic strengths. In addition, the coagulation rates of selected sediments collected from the Pamlico Estuary of North Carolina were determined. Finally...

J. K. Edzwald

1972-01-01

308

Experimental and Theoretical Estimation of Excited Species Generation in Pulsed Electron Beam-Generated Plasmas Produced in Pure Argon, Nitrogen, Oxygen, and Their Mixtures.  

National Technical Information Service (NTIS)

In this report we use optical emission spectroscopy (OES) to determine the excited species produced by a high energy pulsed electron beam (2 kV) in various gases. The gases studied include pure argon, nitrogen, oxygen, and argon/nitrogen and argon/oxygen ...

E. H. Lock R. F. Fernsler S. Slinker S. G. Walton

2011-01-01

309

Treatment of Xanthelasma Palpebrarum with Argon Laser Photocoagulation  

Microsoft Academic Search

Purpose: We report the results of argon laser coagulation of xanthelasma lesions. Methods: Forty eyelids of 24 patients with xanthelasma were treated in 1 to 4 sessions at 2–3 week intervals, using an argon green laser. The laser parameters were as follows: wavelength 514 nm; spot size 500 microns; energy 900 mW; the duration of the laser pulse 0.1–0.2 seconds.

Emel Basar; Halit Oguz; Hakan Ozdemir; Sehirbay Ozkan; Hasim Uslu

2004-01-01

310

Fresh Frozen Plasma in Pump Priming for Congenital Heart Surgery: Evaluation of Effects on Postoperative Coagulation Profiles Using a Fibrinogen Assay and Rotational Thromboelastometry  

PubMed Central

Purpose In this prospective study, the effects of fresh frozen plasma (FFP) included in pump priming for congenital heart surgery in infants and children on post-bypass coagulation profiles were evaluated. Materials and Methods Either 20% albumin (50-100 mL) or FFP (1-2 units) was added to pump priming for patients randomly allocated into control or treatment groups, respectively. Hematologic assays, including functional fibrinogen level, and rotational thromboelastometry (ROTEM®) were measured before skin incision (baseline), after weaning from cardiopulmonary bypass (CPB) and heparin reversal, and at 24 hours (h) in the intensive care unit (ICU). Results All the baseline measurements were comparable between the control and treatment groups of infants and children. After heparin reversal, however, significantly higher fibrinogen levels and less reduced ROTEM parameters, which reflect clot formation and firmness, were demonstrated in the treatment groups of infants and children. At 24 h in the ICU, hematologic assays and ROTEM measurements were comparable between the control and treatment groups of infants and children. Transfusion requirements, excluding FFP in pump prime, and postoperative bleeding were comparable between the control and treatment groups of infants and children. Conclusion Although clinical benefits were not clearly found, the inclusion of FFP in pump priming for congenital heart surgery in infants and children was shown to improve the hemodilution-related hemostatic dysfunction immediately after weaning from CPB and heparin reversal.

Lee, Jong Wha; Yoo, Young-Chul; Park, Han Ki; Bang, Sou-Ouk; Lee, Ki-Young

2013-01-01

311

Tunable diode laser absorption spectroscopy of argon metastable atoms in Ar\\/C2H2 dusty plasmas  

Microsoft Academic Search

The tunable diode laser absorption spectroscopy method was used to measure Ar metastable density in order to study the dust growth process in hydrocarbon-containing plasmas. A simple model was proposed that successfully interprets the experimental results of pristine plasmas. The model is also suitable for explaining the influence of dust particle size on metastable density and for examining the dust

Hoang Tung Do; Vladimir Sushkov; Rainer Hippler

2009-01-01

312

Effect of Radiation and Non-Maxwellian Electron Distribution on Relaxation Processes in an Atmospheric Cesium Seeded Argon Plasma.  

National Technical Information Service (NTIS)

A model, describing the time dependent behavior of a noble gas MHD generator plasma, was set up. The model calculates the relaxation for ionization or recombination as a stepwise temperature development, once the initial and final conditions are given. Ra...

C. A. Borghi A. Veefkind J. M. Wetzer

1982-01-01

313

Acetylene - Argon Plasmas Measured at a Biased Substrate Electrode for Diamond-Like Carbon Deposition. Part 1: Mass Spectroscopy  

Microsoft Academic Search

We report, for the first time, quadrupole mass spectrometry of neutral and\\u000apositive ionic hydrocarbon species measured at the rf biased substrate\\u000aelectrode of an inductively coupled plasma for acetylene rich C2H2:Ar mixtures\\u000aunder various bias, frequency and pressure conditions. It has been observed\\u000athat, irrespective of initial gas mixture, the resultant plasma is dominated by\\u000aargon neutrals and ions.

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

2008-01-01

314

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

315

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

PubMed

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

Ponta, Michaela; Frentiu, Maria; Frentiu, Tiberiu

2012-06-01

316

Innate Immunity and Coagulation  

PubMed Central

Summary Infection frequently elicits a coagulation response. Endotoxin triggers the formation of tissue factor initiating coagulation, down regulates anticoagulant mechanisms including the protein C pathway and heparin-like proteoglycans and up regulates plasminogen activator inhibitor. The overall physiological result of this is to promote coagulation through enhancing initiation, suppressing negative regulation and impairing fibrin removal. The response to infection also leads to tissue destruction. Nucleosomes and histones released from the injured cells trigger further inflammation, protection from the pathogen but further tissue injury leading to multi-organ failure. Such a complex response to infection presumably arises due to the role of coagulation in the control and clearance of the infectious agent.

Esmon, Charles T.; Xu, Jun; Lupu, Florea

2011-01-01

317

Optimisation of a new continuous UV assay for the determination of blood coagulation factor XIII activity in human plasma.  

PubMed

The new photometric assay described by Fickenscher et al. (Thromb. Haemostas. 65 (1991) 535-540) for the determination of factor XIII facilitates the diagnosis of factor XIII deficiency. In spite of easy handling, this test should be used critically. Patients with hyperfibrinogenaemia showed factor XIII activities of less than 20%, whereas with an optimized assay we found normal factor XIII values. Also, the use of a fixed period of incubation for the analysis is questionable, because the period of constant reaction rate occurs earlier and is shorter with high factor XIII activities and later and longer with low factor XIII activities. A linear relation between factor XIII activity and signal only exists up to 80% of activity. In some plasma samples from patients with hyperfibrinogenaemia the factor XIII determination actually shows decreased values for factor XIII. During the reaction, a fibrin clot is formed. The resulting turbidity simulates an increase in absorbance so that NADH consumption is apparently decreased. In six patients with hyperfibrinogenaemia (8.1-9.4 g/l), a factor XIII activity of 26 U/l or less was determined. Using 50 microliters instead of 100 microliters sample volume, 50% (3/6) of the patients showed a normal factor XIII activities (80-96 U/l), whereas 50% (3/6) values of 6-15 U/l were found. In our modified assay we measured normal factor XIII activities (72-151 U/l) in all 6 patients. The procedure is optimized by reducing the sample volume from 100 microliters to 50 microliters.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7918847

Heins, M; Fahron, U; Withold, W; Rick, W

1994-06-01

318

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

Microsoft Academic Search

A downstream microwave plasma etcher has been constructed to study the etch dynamics of polyphenylene oxide laminates (PPO) using CF4\\/O 2\\/Ar reactant gases. The results of optical emission spectroscopy indicate that both atomic fluorine and atomic oxygen participate in the etching process. Quantitative analysis of downstream etch products based on the real time measurement of molecular-beam mass spectrometry shows major

Chia-Chang Hsu

1999-01-01

319

Coagulation activation in autoimmune bullous diseases  

PubMed Central

The main autoimmune blistering skin disorders are pemphigus vulgaris (PV) and bullous pemphigoid (BP). They differ in the inflammatory infiltrate, which is more intense in BP. Inflammation is known to activate coagulation in several disorders. Local and systemic activation of coagulation was evaluated in BP and PV. We studied 20 BP patients (10 active and 10 remittent), 23 PV patients (13 active and 10 remittent) and 10 healthy subjects. The coagulation markers prothrombin fragment F1+2 and D-dimer were measured by enzyme-immunoassays in plasma. The presence of tissue factor (TF), the main initiator of blood coagulation, was evaluated immunohistochemically in skin specimens from 10 patients with active PV, 10 patients with active BP and 10 controls. Plasma F1+2 and D-dimer levels were significantly high in active BP (P = 0·001), whereas in active PV the levels were normal. During remission, F1+2 and D-dimer plasma levels were normal in both BP and PV. TF immunoreactivity was found in active BP but neither in active PV nor in normal skin. TF reactivity scores were higher in active BP than in controls or active PV (P = 0·0001). No difference in TF scores was found between active PV and controls. BP is associated with coagulation activation, which is lacking in PV. This suggests that BP but not PV patients have an increased thrombotic risk. The observation that thrombotic complications occur more frequently in BP than in PV further supports this view.

Marzano, A V; Tedeschi, A; Spinelli, D; Fanoni, D; Crosti, C; Cugno, M

2009-01-01

320

Discharge Characteristics of an Atmospheric Pressure Argon Plasma Jet Generated with Screw Ring-Ring Electrodes in Surface Dielectric Barrier Discharge  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure argon plasma jet with screw ring-ring electrodes in surface dielectric barrier discharge is generated by a sinusoidal excitation voltage at 8 kHz. The discharge characteristics, such as rotational and vibrational temperature of nitrogen, electronic excitation temperature, oxygen atomic density, nitrogen molecular density, and average electron density, are estimated. It is found that the rotational temperature of nitrogen is in the range of 352 ~ 392 K by comparing the simulated spectrum with the measured spectrum at the C3?u ? B3?g(?v = -2) band transition, the electronic excitation temperature is found to be in the range of 3127 ~ 3230 K by using the Boltzmann plot method, the oxygen atomic and nitrogen molecular density are of the order of magnitude of 1016 cm-3 by the actinometry method, and the average electron density is of the order of magnitude of 1012 cm-3 by the energy balance equation. Besides, the effective power, conduction, and displacement current are measured during the discharge.

Hong, Yi; Lu, Na; Pan, Jing; Li, Jie; Wu, Yan

2013-08-01

321

Disseminated intravascular coagulation associated with hepatitis in late pregnancy  

PubMed Central

A patient with viral hepatitis in the third trimester of pregnancy is described. She developed acute hepatic failure in the postpartum period which was associated with evidence of intravascular coagulation. Following therapy with heparin and fresh-frozen plasma, the patient made a dramatic recovery. Hepatitis developed during the puerperium may predispose to pathological intravascular coagulation and hepatocellular necrosis may thereby be perpetuated.

Jones, C. T. A.; Birch, C. R.; Poller, L.; Dymock, I. W.

1973-01-01

322

Use of a nitrogen-argon plasma to improve adherence of sputtered titanium carbide coatings on steel  

NASA Technical Reports Server (NTRS)

Friction and wear experiments on 440-C steel surfaces that had been RF-sputtered with titanium carbide when a small percentage of nitrogen was added to the plasma were conducted. X-ray photoelectron spectroscopy and X-ray diffraction were used to analyze the resultant coatings. Results indicate that a small partial pressure of nitrogen (about 0.5%) markedly improves the adherence, friction, and wear properties when compared with coatings applied on sputter-etched oxidized surfaces or in the presence of a small oxygen partial pressure. The improvements are related to the formation of an interface containing a mixture of the nitrides of titanium and iron, which are harder than their corresponding oxides.

Brainard, W. A.; Wheeler, D. R.

1979-01-01

323

Blood folate status and expression of proteins involved in immune function, inflammation, and coagulation: biochemical and proteomic changes in the plasma of humans in response to long-term synthetic folic acid supplementation.  

PubMed

We used plasma proteomics to identify human proteins responsive to folate status. Plasma was collected from subjects treated with placebo or 1.2 mg of folic acid daily for 12 weeks in a randomized controlled trial. Homocysteine and folate were measured by immunoassay and uracil misincorporation by electrophoresis. The plasma proteome was assessed by 2-D gel electrophoresis, and proteins were identified by LC MS/MS. 5-methylTHF increased 5-fold (P = 0.000003) in response to intervention. Red cell folate doubled (P = 0.013), and lymphocyte folate increased 44% (P = 0.0001). Hcy and uracil dropped 22% (P = 0.0005) and 25% (P = 0.05), respectively. ApoE A-1, alpha-1-antichymotrypsin, antithrombin, and serum amyloid P were downregulated, while albumin, IgM C, and complement C3 were upregulated (P < 0.05). More than 60 proteins were significantly associated with folate pre- and postintervention (P < 0.01). These were categorized into metabolic pathways related to complement fixation (e.g., C1, C3, C4, Factor H, Factor 1, Factor B, clusterin), coagulation (e.g., antithrombin, alpha-1-antitrypsin, kininogen) and mineral transport (e.g., transthyretin, haptoglobin, ceruloplasmin). Low folate status pre- and post-treatment were associated with lower levels of proteins involved in activation and regulation of immune function and coagulation. Supplementation with synthetic folic acid increased expression of these proteins but did not substantially disrupt the balance of these pathways. PMID:20143872

Duthie, Susan J; Horgan, Graham; de Roos, Baukje; Rucklidge, Garry; Reid, Martin; Duncan, Gary; Pirie, Lynn; Basten, Graham P; Powers, Hilary J

2010-04-01

324

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

NASA Astrophysics Data System (ADS)

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

Major, Helen E.

325

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

326

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

SciTech Connect

The coupling of flow injection analysis (FIA) or high-performance liquid chromatography (HPLC) techniques to inductively coupled plasma atomic emission spectrometry (ICP-AES) offers new and attractive approaches for the determination of elemental concentrations in a wide variety of sample matrices. One of the most attractive features that FIA offers is a rapid and precise means of automating sample introduction into an ICP for simultaneous, multielement analysis at the trace, minor, and major constituent level with minimal sample consumption. The utilization of the ICP as a detector for HPLC retains most of the advantages of FIA-ICP, while providing the analyst with a powerful and versatile means of compound separation. This added dimension becomes particularly important when metal speciation is of primary interest, rather than total metal content. To date, the coupling of FIA and HPLC to the ICP has only been accomplished using conventional cross-flow, concentric, or Babington-type pneumatic nebulizers. Limits of detection under these conditions have generally been observed to be poorer when compared to conventional continuous sample flow conditions. These limitations have been attributed to the large dead-volume and the sample losses associated with conventional nebulizers and band broadening of eluents from FIA transfer tubing or HPLC columns prior to entering the nebulizer unit. In an effort to resolve these difficulties, a microconcentric nebulizer has been developed which is inserted directly into the tip of a conventional sample introduction tube of an ICP torch. Preliminary data on the potential utility of direct liquid sample introduction into the ICP are presented. 12 references, 6 figures, 1 table.

Lawrence, K.E.; Rice, G.W.; Fassel, V.A.

1984-02-01

327

Coagulation in chaotic flows  

NASA Astrophysics Data System (ADS)

We study coagulation in the flow field of a time-periodic deterministic chaotic flow and focus on the simplest case: point particles convected without diffusion and allowed to coagulate with probability 1 when the distance is less than d. An analysis of the underlying physics is presented. Under ``well-mixed'' conditions the system behaves as if the particles were moved by Brownian motion, and a simple kinetic model describes the main results. The poorly mixed case is considerably more complex. Spatial inhomogeneities result from competition between the rate of coagulation and mixing, and trapping and leaking of clusters due to Kolmogorov-Arnold-Moser surfaces.

Muzzio, F. J.; Ottino, J. M.

1988-09-01

328

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

329

Disseminated Intravascular Coagulation  

MedlinePLUS

... intravascular coagulation (ko-ag-u-LA-shun), or DIC, is a condition in which blood clots form ... vessels, which can damage the body's organs. In DIC, the increased clotting uses up platelets (PLATE-lets) ...

330

Argon Excimer Laser.  

National Technical Information Service (NTIS)

The electron-beam-pumped argon eximer laser is investigated and tuned for the first time. The electron beam is generated by means of an improved coaxial field emission diode in which argon gas is excited with power densities of 0.3 GW/cm exp 3 for 18 ns. ...

W. G. Wrobel

1981-01-01

331

Argon Purification Reference and Recommendation.  

National Technical Information Service (NTIS)

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 als...

J. Wu

1991-01-01

332

Characterization of the coagulation system in healthy dolphins: the coagulation factors, natural anticoagulants, and fibrinolytic products  

Microsoft Academic Search

In dolphins, blood pooling and acidosis from lack of oxygenation with prolonged underwater stay are not associated with intravascular clotting as it would be in terrestrial mammals, while shed blood clots promptly, and intravascular clots form after death. This intriguing physiologic adaptation prompted further investigation of the coagulation system in the dolphin. We studied the plasma from 17 dolphins (Tursiops

Rita F. Tibbs; M. Tarek Elghetany; Lethu T. Tran; W. Van Bonn; T. Romano; Daniel F. Cowan

2005-01-01

333

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

334

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

Microsoft Academic Search

Hydrogen, oxygen, and hydrogen peroxide have been measured downstream of an atmospheric pressure humid argon dielectric barrier discharge. The yield of the three species was studied as a function of the discharge power and gas flow rate. Hydrogen peroxide was measured after dissolution into water downstream of the discharge, while hydrogen and oxygen were measured in the gas phase. The

M. J. Kirkpatrick; B. Dodet; E. Odic

335

Disseminated Intravascular Coagulation  

Microsoft Academic Search

Disseminated intravascular coagulation (DIC) is a complex disorder, with pathophysiology being variable and highly dependent upon the triggering event(s), host response(s) and comorbid conditions. As a result of these complicated interactions, the clinical expression and laboratory findings are varied, thereby affecting the specifics of diagnosis and therapeutic approaches. The highly complex and variable pathophysiology of DIC often results in a

Rodger L. Bick; Banu Arun; Eugene P. Frenkel

1999-01-01

336

Bipolar coagulation in neurosurgery.  

PubMed

Coagulation is an essential part of a surgical procedure, especially in neurosurgery. Beginning in the early years of this century, various techniques have been used to control bleeding at the surgical site. Over the years, these techniques have led to the invention of the bipolar coagulator and its modifications. Prevention of charring and tissue adhesion have been the goals of bipolar coagulator manufacturers all over the world; new techniques and different metallurgical compositions for the forceps have been tried to achieve these results. The NS2000, with its microprocessor-based controlled coagulative sequence, can be a good system for reducing tissue adhesion and charring under desired limits of low output power ranges provided by the system. Comparable results can also be obtained with the Malis CMC III and Synergy Malis systems with irrigation channels. These systems have the additional advantages of providing higher power outputs at lower panel settings and a maximum power output greater than that of NS2000. For neurosurgeons who need the additional option of cutting, the Malis CMC III is the recommended system. PMID:9508124

Dujovny, M; Dujovny, N; Gundamraj, N R; Misra, M

1998-03-01

337

Thermoconductivity of Solid Argon.  

National Technical Information Service (NTIS)

The technical difficulties concerned with the preparation of rods of solid argon of good quality, their cooling at helium temperature, and their thermal contact with the measuring heater and thermometers were overcome. Measurements in the temperature rang...

G. Boato

1964-01-01

338

Argon Purification Reference and Recommendation  

Microsoft Academic Search

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

J. Wu

1991-01-01

339

Coagulation monitor based on serum migration through absorbent materials  

Microsoft Academic Search

I describe a method to measure blood coagulation prop- erties, based on the hypothesis that the distance the serum component of a clotted plasma sample moves through a suitable absorbent material should be propor- tional to the blood's ability to clot. A simple apparatus was constructed to test this principle, in which an absorbent strip contacts clotted plasma samples. At

Paul E. Wilson

340

Role of tissue factor in disseminated intravascular coagulation  

Microsoft Academic Search

We examined plasma antigen levels of tissue factor (TF) in 95 cases of disseminated intravascular coagulation (DIC), to investigate the role of TF in DIC. A significant elevation of plasma antigen levels of TF was observed in cases of DIC associated cancer. However, no such significant elevation was observed in cases of DIC associated with acute promyelocytic leukemia (APL), acute

H. Asakura; Y. Kamikubo; A. Goto; Y. Shiratori; M. Yamazaki; H. Jokaji; M. Saito; C. Uotani; I. Kumabashiri; E. Morishita; K. Aoshima; S. Nakamura; T. Matsuda

1995-01-01

341

Platelet-dependent thrombin generation in patients with diabetes mellitus: Effects of glycemic control on coagulability in diabetes  

Microsoft Academic Search

Objectives. This study sought to assess the usefulness of platelet-dependent thrombin generation as an index of coagulability in diabetes and to determine the effect of glycemic control on coagulability in diabetes.Background. It is important to investigate the interaction of platelets and the coagulation factors to clarify the processes of the coagulation system in detail.Methods. Platelet-rich plasma (150 × 109\\/liter), 0.5

Isao Aoki; Katsuya Shimoyama; Nobuo Aoki; Masashi Homori; Atsuo Yanagisawa; Kazuhiko Nakahara; Yohko Kawai; Shin-Ichi Kitamura; Kyozo Ishikawa

1996-01-01

342

Calculation of radiation from argon shock layers  

NASA Technical Reports Server (NTRS)

The accuracy of calculations of the radiation emissions from argon plasmas produced by the shock layers over blunt bodies is assessed. The existing theoretical and experimental spectroscopic data on argon are collated. A set of such data is selected for use in the radiative transfer calculations. Calculations are performed for the stagnation regions of the shock layers over laboratory-sized models using these data, and the results are compared with the existing experimental results obtained in a shock-tube. Through this comparison and a parametric study it is shown that radiative heat fluxes at the stagnation point in an argon environment can be calculated within an uncertainty of about 15%. It is shown also that radiative heat fluxes of the order of 100 kW/sq cm can be produced in the existing laboratory facilities.

Park, C.

1982-01-01

343

Change in blood coagulation indices as a function of the incubation period of plasma in a constant magnetic field. [considering heparin tolerance and recalcification  

NASA Technical Reports Server (NTRS)

The influence of a constant magnetic field (CMF) with a strength of 250 and 2500 oersteds on the recalcification reaction and the tolerance of plasma to heparin was studied as a function of the exposure time of the plasma to the CMF. The maximum and reliable change in the activation of the coagulatory system of the blood was observed after a 20-hour incubation of the plasma in a CMF. As the exposure time increased, the recalcification reaction changed insigificantly; the difference between the mean arithmetic of the experiment and control values was not statistically reliable. The tolerance of the plasma to heparin as a function of the exposure time to the CMF of the plasma was considerably modified, an was statistically reliable.

Yepishina, S. G.

1974-01-01

344

Tissue gas and blood analyses of human subjects breathing 80% argon and 20% oxygen  

NASA Technical Reports Server (NTRS)

Eight human volunteers, individually studied in a hyperbaric chamber, breathed: (1) air at 1 ATA; (2) 80% argon and 20% oxygen at 1 ATA for 30 min; (3) air at 1 ATA for 30 min; (4) 100% O2 at 1 ATA for 30 min; (5) air at 1 ATA for 30 min; (6) 100% O2 at 2 ATA for 60 min; and (7) 80% argon and 20% oxygen at 1 ATA for 30 min. Oxygen, carbon dioxide, nitrogen, and argon tensions were measured in muscle and subcutaneous tissue by mass spectroscopic analyses. Venous blood obtained at regular intervals was analyzed for coagulation and fibrinolytic factors. Inert gas narcosis was not observed. After breathing argon for 30 min, muscle argon tensions were almost three times the subcutaneous tensions. Argon wash-in mirrored nitrogen wash-out. Argon wash-in and wash-out had no effect on tissue PO2 or PCO2. Coagulation and fibrinolytic changes usually associated with vascular bubbles were absent.

Horrigan, D. J.; Wells, C. H.; Guest, M. M.; Hart, G. B.; Goodpasture, J. E.

1979-01-01

345

Chronic sleep deprivation markedly reduces coagulation factor VII expression  

PubMed Central

Chronic sleep loss, a common feature of human life in industrialized countries, is associated to cardiovascular disorders. Variations in functional parameters of coagulation might contribute to explain this relationship. By exploiting the mouse model and a specifically designed protocol, we demonstrated that seven days of partial sleep deprivation significantly decreases (?30.5%) the thrombin generation potential in plasma evaluated upon extrinsic (TF/FVIIa pathway) but not intrinsic activation of coagulation. This variation was consistent with a decrease (?49.8%) in the plasma activity levels of factor VII (FVII), the crucial physiologicalal trigger of coagulation, which was even more pronounced at the liver mRNA level (?85.7%). The recovery in normal sleep conditions for three days completely restored thrombin generation and FVII activity in plasma. For the first time, we demonstrate that chronic sleep deprivation on its own reduces, in a reversible manner, the FVII expression levels, thus influencing the TF/FVIIa activation pathway efficiency.

Pinotti, Mirko; Bertolucci, Cristiano; Frigato, Elena; Branchini, Alessio; Cavallari, Nicola; Baba, Kenkichi; Contreras-Alcantara, Susana; Ehlen, J. Christopher; Bernardi, Francesco; Paul, Ketema N.; Tosini, Gianluca

2010-01-01

346

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

347

Ventricular metastasis resulting in disseminated intravascular coagulation  

PubMed Central

Background Disseminated Intravascular Coagulation (DIC) complicates up to 7% of malignancies, the commonest solid organ association being adenocarcinoma. Transitional Cell Carcinoma (TCC) has rarely been associated with DIC. Case presentation A 74-year-old woman with TCC bladder and DIC was found to have a cardiac lesion suspicious for metastatic disease. The DIC improved with infusion of plasma and administration of Vitamin K, however the cardiac lesion was deemed inoperable and chemotherapy inappropriate; given the patients functional status. We postulate that direct activation of the coagulation cascade by the intraventricular metastasis probably triggered the coagulopathy in this patient. Conclusion Cardiac metastases should be considered in cancer patients with otherwise unexplained DIC. This may influence treatment choices.

John, Thomas; Davis, Ian D

2005-01-01

348

Acquired coagulation inhibitor delaying fibrinopeptide release.  

PubMed

A 14-yr-old girl Down syndrome developed a unique type of circulating inhibitor causing a mild bleeding tendency and interfering strongly with coagulation tests, including reptilase time, and with the reaction of purified fibrinogen and thrombin. The concentration of all coagulation factors was normal. The inhibitor had no direct effect on thrombin activity or on the aggregation of fibrin monomer in plasma. Chromatography on DEAE-cellulose and neutralization by immune sera revealed that the inhibitor was an immunoglobulin of IgG class with both kappa and lambda determinants. Isolated inhibitor delayed the release of fibrinopeptide A from a normal fibrinogen reacting with thrombin and retarded the onset of visible clotting, but had no effect on the the final degree of clottability. The clinical and laboratory features of this patient resemble those of patients with congenital dysfibrinogenemia associated with abnormal fibrinopeptide release. PMID:758215

Marciniak, E; Greenwood, M F

1979-01-01

349

Modelling of a supersonic ICP argon-hydrogen expansion  

NASA Astrophysics Data System (ADS)

An expanding argon-hydrogen plasma is investigated by means of simulations. The model is a hydrodynamical model specific for plasma expansions, taking into account the conservation laws of mass, momentum and energy. The code includes the Rankine-Hugoniot relations to calculate shock jump conditions. Results are shown for the expansion from an inductively coupled plasma (ICP) with a separated Laval nozzle. The expansion discussed here is a `weakly' under-expanding argon-hydrogen plasma. The results from the ICP expansion are verified with probe measurements.

Burm, K. T. A. L.; Jodoin, B.; Proulx, P.; Boulos, M. I.

2003-08-01

350

Effect of oral administration of unfractionated heparin (UFH) on coagulation parameters in plasma and levels of urine and fecal heparin in dogs.  

PubMed

The effects of heparin administration, by the oral route, were evaluated in dogs. In single and multiple dose studies (single 7.5 mg/kg, multiple 3 × 7.5 mg/kg per 48 h), plasma, urine, and fecal samples were collected at various times up to 120 h after oral administration of unfractionated heparin. Changes in plasma and urine anti-Xa activity, plasma and urine anti-IIa activity, plasma activated partial thromboplastin time (APTT) and antithrombin (ATIII), and chemical heparin in urine and feces were examined with time. There was support for heparin absorption, with significant differences in APTT, heparin in plasma as determined by anti-Xa activity (Heptest) in the single dose study and plasma anti-Xa activity, anti-IIa activity and ATIII; and chemical heparin in urine in the multiple dose study. No clinical evidence of bleeding was detected in any dog during the studies. Oral heparin therapy may be applicable for thromboembolic disease in animals. Further studies are warranted to determine the effects of oral heparin at the endothelial level in the dog. PMID:24982550

Erickson, Malathi; Hiebert, Linda M; Carr, Anthony P; Stickney, Jocelyn D

2014-07-01

351

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

352

Routine coagulation assays underestimate levels of antithrombin-dependent drugs but not of direct anticoagulant drugs in plasma from patients with cirrhosis.  

PubMed

There is increasing recognition that thrombotic complications may occur in patients with cirrhosis, and literature on antithrombotic treatment in these patients is rapidly emerging. Due to extensive haemostatic changes in patients with cirrhosis, careful monitoring of anticoagulant therapy may be required. Recent data suggest that plasma levels of low molecular weight heparin (LMWH) are substantially underestimated by the anti-activated factor X (anti-Xa) assay in patients with cirrhosis. We studied the in vitro recovery of antithrombin (AT)-dependent and -independent anticoagulant drugs in plasma from 26 patients with cirrhosis and 30 healthy controls and found substantially reduced anti-Xa levels when AT-dependent anticoagulant drugs were added to the plasma of patients with cirrhosis. LMWH (0·2 U/ml) had the poorest recovery in plasma from patients with cirrhosis (0·13 ± 0·06 U/ml, compared to 0·23 ± 0·03 U/ml in controls, P < 0·0001), followed by unfractionated heparin and fondaparinux. In contrast, the recovery of rivaroxaban and dabigatran was identical between patients and controls. These data suggest that the anti-Xa assay cannot be used to monitor AT-dependent anticoagulant drugs in patients with cirrhosis, as it substantially underestimates drug levels. The direct factor Xa and IIa inhibitors, however, may be monitored through the respective anti-Xa and anti-IIa assays in patients with cirrhosis. PMID:24219333

Potze, Wilma; Arshad, Freeha; Adelmeijer, Jelle; Blokzijl, Hans; van den Berg, Arie P; Porte, Robert J; Lisman, Ton

2013-12-01

353

Excimer Emission from Argon Microhollow Cathode Discharges  

NASA Astrophysics Data System (ADS)

Excimer emission from direct current microhollow cathode discharges had been studied for rare gases and mixtures of rare gases and halides as working gases [1]. In static xenon, the dc efficiency was measured as 6%-9%. In static argon, however, the efficiency is only on the order of 1%. This relatively low value was found to be due to excimer quenching processes caused by impurities. By flowing the argon, rather than operating under static conditions we could increase the efficiency to 6%. Applying a 10 ns pulse of 600 V to the DC discharge in argon resulted in an increased intensity by a factor of six. The decay time for argon excimer emission was found to be 500 ns, indicating that quenching processes even with purging of the discharge chamber are still more effective by a factor of six in depopulating the excimer level than excimer radiation. The major quenching effect is based on resonant energy transfer from the argon excimer to atomic oxygen [2]. The addition of small amounts of oxygen allowed us therefore to convert the argon excimer emission centered at 128 nm into narrowband emission at 130.4 nm (oxygen triplet) with an optical power of up to 13 mW.This material was supported by NSF (CTS-0078618).[1] Karl H. Schoenbach, Ahmed El-Habachi, Mohamed M. Moselhy, Wenhui Shi, and Robert H. Stark, Physics of Plasmas 7, 2186 (2000). [2] M. Moselhy, R.H. Stark, K.H. Schoenbach, and U. Kogelschatz, Appl. Phys. Lett. 78, 880 (2001).

Moselhy, Mohamed; Schoenbach, Karl H.

2002-10-01

354

Blood Coagulation, Inflammation and Malaria  

PubMed Central

I. ABSTRACT Malaria remains a highly prevalent disease in more than 90 countries and accounts for at least 1 million deaths every year. Plasmodium falciparum infection is often associated with a procoagulant tonus characterized by thrombocytopenia and activation of the coagulation cascade and fibrinolytic system; however, bleeding and hemorrhage are uncommon events, suggesting that a compensated state of blood coagulation activation occurs in malaria. This article i) reviews the literature related to blood coagulation and malaria in a historic perspective, ii) describes basic mechanisms of coagulation, anticoagulation, and fibrinolysis, iii) explains the laboratory changes in acute and compensated disseminated intravascular coagulation (DIC), iv) discusses the implications of tissue factor (TF) expression in the endothelium of P. falciparum-infected patients, and v) emphasizes the pro-coagulant role of parasitized erythrocytes (pRBC) and activated platelets in the pathogenesis of malaria. This article also presents the ‘Tissue Factor Model’ (TFM) for malaria pathogenesis, which places TF as the interface between sequestration, endothelial cell activation, blood coagulation disorder and inflammation often associated with the disease. The relevance of the coagulation-inflammation cycle for the multiorgan dysfunction and coma is discussed in the context of malaria pathogenesis.

Francischetti, Ivo M. B.; Seydel, Karl B.; Monteiro, Robson Q.

2010-01-01

355

Virus Removal by Chemical Coagulation.  

National Technical Information Service (NTIS)

Using bacterial viruses (Bacteriophages T4 and MS2 against Escherichia coli) as models and aluminum as the coagulant metal ion, it was shown that removal of viruses from water by chemical coagulation and flocculation with aluminum sulfate consists of a pr...

R. S. Engelbrecht M. Chaudhuri

1969-01-01

356

[An experimental study of the coagulating properties of a laser beam applied to fix titanium prostheses of auditory ossicles with the use of platelet-rich plasma].  

PubMed

The displacement of prostheses of auditory ossicles at the concluding stage of surgery and in the early postoperative period is one of the factors influencing the functional outcome of stapedoplasty. The objective of the present experimental study was to estimate the effectiveness of the use of platelet-rich plasma as an alloy for the laser welding in order to improve fixation of titanium prostheses employed in ossiculoplastic surgery. The results of a series of experiments undertaken to assess the possibility of stabilization of titanium prostheses in the desired position with the help of laser welding indicate that this technique with the use of platelet-rich plasma as an alloy may be a reliable method for the fixation of the reconstructed chain of ossicles in the desired position. PMID:24300758

Semenov, V F; Semenov, F V

2013-01-01

357

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

358

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

359

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.

Colace, Thomas V.; Tormoen, Garth W.

2014-01-01

360

Understanding Coagulation Disorders  

NSDL National Science Digital Library

This tutorial is designed to aid medical students at all levels understand the laboratory diagnosis of disorders of coagulation. It includes introductory material on the basic laboratory tests, their general application and pitfalls in interpretation. The introduction is followed by a series of short clinical vignettes illustrating a variety of clotting disorders. QuickTime movie player and Java script runtime plug-in scripts are required for some pages. The tutorial concludes with a short self-help quiz covering the major points developed. The plug-ins noted above are available free at the following sites: http://www.apple.com/quicktime/download/win.html and http://www.sun.com/ Questions should be directed to Dr. Mark Braun; braunm@indiana.edu.Annotated: false

Braun, Mark

2009-11-30

361

Effects of the Length of a Cylindrical Solid Shield on the Entrainment of Ambient Air into Turbulent and Laminar Impinging Argon Plasma Jets  

Microsoft Academic Search

When materials processing is conducted in air surroundings by use of an impinging plasma jet, the ambient air will be entrained\\u000a into the materials processing region, resulting in unfavorable oxidation of the feedstock metal particles injected into the\\u000a plasma jet and of metallic substrate material. Using a cylindrical solid shield may avoid the air entrainment if the shield\\u000a length is

Hai-Xing Wang; Xi Chen; Wenxia Pan

2008-01-01

362

Clinical and prognostic significance of coagulation assays in lung cancer.  

PubMed

Activation of coagulation and fibrinolysis is frequently encountered among cancer patients. Such tumors are supposed to be associated with higher risk of invasion, metastases and eventually worse outcome. The aim of this study is to explore the prognostic value of blood coagulation tests for lung cancer patients. The study comprised 110 lung cancer patients. Pretreatment blood coagulation tests including PT, aPTT, PTA, INR, D-dimer, fibrinogen levels and platelet counts were evaluated. The plasma level of all coagulation tests revealed statistically significant difference between patient and control group (p < 0.001). There was a significant association between D-Dimer levels and histological subtypes of NSCLC, pointing an elevated plasma D-dimer level in squamous cell cancer (p = 0.035). Patients with extensive stage SCLC exhibited evidently higher levels of D-Dimer, INR and PLT (p = 0.037, p = 0.042, p = 0.04, respectively). Prolongation of PT and INR had statistically significant adverse effect on survival (p = 0.05 and p = 0.014, respectively). Although prolonged aPTT and high levels of D-dimer was associated with worse survival, the difference was not statistically significant (p = 0.117, p = 0.104). Multivariate analysis revealed INR as the sole independent prognostic variable among coagulation parameters (p = 0.05). In conclusion, elevation of PT and INR are associated with decreased survival in lung cancer patients. PMID:23200643

Tas, Faruk; Kilic, Leyla; Serilmez, Murat; Keskin, Serkan; Sen, Fatma; Duranyildiz, Derya

2013-03-01

363

Coagulation defects resulting from ambient temperature-induced hypothermia.  

PubMed

Ambient temperature-induced hypothermia noted in trauma patients is frequently accompanied by a bleeding diathesis despite "laboratory normal" coagulation values. To document this impression, the following experiment was conducted. Coagulation studies and platelet function studies were performed in ten minipigs during induced whole body hypothermia (40 degrees C to 34 degrees C) and rewarming. Cooling was achieved in 2 to 3 hours and rewarming took 4 to 5 hours. In addition, similar coagulation and platelet function studies were conducted on plasma samples from the same animals that were cooled and then rewarmed in a water bath. Platelet counts and function as measured by Sonoclot analysis and aggregation did not decrease significantly with hypothermia in either model. Plasma cooled in a water bath demonstrated abnormal PT and aPTT (p < 0.001). Whole body hypothermia demonstrated abnormal bleeding time and PT (p < 0.001). Ambient temperature-induced hypothermia produced significant coagulation defects in a porcine model. Some of the coagulation defects were most pronounced during rewarming. PMID:8189462

Staab, D B; Sorensen, V J; Fath, J J; Raman, S B; Horst, H M; Obeid, F N

1994-05-01

364

THE EFFECT OF COLLOIDAL SILICA ON BLOOD COAGULATION  

Microsoft Academic Search

Colloidal silica accelerates blood coagulation by adsorption and partial denaturation of a specific plasma protein, the Hageman factor. Quantitative measurements show that the activity of the silica depends on the particle diameter. It is suggested that geometrical relations between the silica and the protein molecules account for these differences in activity. The implications of certain anomalies of this reaction are

J Margolis

1961-01-01

365

Future liquid Argon detectors  

NASA Astrophysics Data System (ADS)

The Liquid Argon Time Projection Chamber offers an innovative technology for a new class of massive detectors for rare-event detection. It is a precise tracking device that allows three-dimensional spatial reconstruction with mm-scale precision of the morphology of ionizing tracks with the imaging quality of a "bubble chamber", provides dE/dx information with high sampling rate, and acts as high-resolution calorimeter for contained events. First proposed in 1977 and after a long maturing process, its holds today the potentialities of opening new physics opportunities by providing excellent tracking and calorimetry performance at the relevant multi-kton mass scales, outperforming other techniques. In this paper, we review future liquid argon detectors presently being discussed by the neutrino physics community.

Rubbia, A.

2013-02-01

366

Isentropic Compression of Argon  

SciTech Connect

We are studying the transition of argon from an insulator to a conductor by compressing the frozen gas isentropically to pressures at which neighboring atomic orbitals overlap sufficiently to allow some electron motion between atoms. Argon and the other rare gases have closed electron shells and therefore remain montomic, even when they solidify. Their simple structure makes it likely that any measured change in conductivity is due to changes in the atomic structure, not in molecular configuration. As the crystal is compressed the band gap closes, allowing increased conductivity. We have begun research to determine the conductivity at high pressures, and it is our intention to determine the compression at which the crystal becomes a metal.

H. Oona; J.C. Solem; L.R. Veeser, C.A. Ekdahl; P.J. Rodriquez; S.M. Younger; W. Lewis; W.D. Turley

1997-08-01

367

Influence of haematocrit on international normalised ratio (INR) differences between a whole blood point-of-care coagulation monitor and reference prothrombin time in plasma.  

PubMed

The CoaguChek S system is designed for use in patient self-testing. In this system a whole blood sample without sodium citrate is applied to a test strip containing thromboplastin and iron oxide particles. The detection principle is based on fibrin formation which inhibits and finally stops the movement of the iron oxide particles. In the classic prothrombin time (PT) test, citrate plasma is mixed with thromboplastin and an excess of calcium ions. In the monitoring of vitamin K-antagonist (VKA) treatment, all results are expressed on a common scale, i.e. international normalised ratio (INR). In patients on long-term VKA treatment, INRs were determined by the CoaguChek S system and reference methods for the classic PT. Four different CoaguChek S strip lots were evaluated. The difference in INR between the reference PT and the CoaguChek S system was negatively correlated to the haematocrit of the patients. We conclude that INR differences between CoaguChek S and plasma PT may be explained in part by the haematocrit. The magnitude of the effect of haematocrit, within the reference interval of 0.37 - 0.51, on the INR difference was not greater than approximately 10% for the combined data of the four strip lots. A bias of less than 10% seems to be acceptable clinically. PMID:19132246

van den Besselaar, Anton M H P; Witteveen, Evelina; van der Meer, Felix J M

2008-12-01

368

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.

2013-01-01

369

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

370

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

PubMed

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

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

2013-01-01

371

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

372

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

373

Effects of RF power on plasma phase reactions and film structure in deposition of a-C:H by styrene/argon discharge  

SciTech Connect

In ion-assisted plasma enhanced chemical vapor depositions (PECVD), the applied RF power affects both plasma phase reactions and deposited film structure. These dual effects are investigated in PECVD of a-C:H films by using styrene and Ar mixture. The films are deposited in a 13.56 MHz, RF driven asymmetric plasma reactor at 25 C. In situ impedance analysis is used to estimate the ion energy and flux at the substrate, while an on-line mass spectrometer (MS) is used to analyze the plasma chemistry, and film structure is characterized by Fourier transform infrared (FTIR) spectroscopy and ellipsometry. The impedance analysis shows that both ion energy and ion flux increase with increasing RF power. The MS data show that the RF power has the major effect on the degree of dissociation of styrene. The FTIR spectra of the deposited films indicate that CH{sub 3} is likely to be the precursor for the diamond-like carbon deposition. The ion energy flux (IEF) is shown to have a significant effect on the film structure. With increasing IEF, films show decreases in hydrogen concentration, increases in sp{sup 2} carbon fraction, and increases in refractive indexes.

Lee, J.H.; Kim, D.S.; Lee, Y.H.; Farouk, B. [Drexel Univ., Philadelphia, PA (United States)

1996-04-01

374

Obstetrical disseminated intravascular coagulation score.  

PubMed

Obstetrical disseminated intravascular coagulation (DIC) is usually a very acute, serious complication of pregnancy. The obstetrical DIC score helps with making a prompt diagnosis and starting treatment early. This DIC score, in which higher scores are given for clinical parameters rather than for laboratory parameters, has three components: (i) the underlying diseases; (ii) the clinical symptoms; and (iii) the laboratory findings (coagulation tests). It is justifiably appropriate to initiate therapy for DIC when the obstetrical DIC score reaches 8 points or more before obtaining the results of coagulation tests. Improvement of blood coagulation tests and clinical symptoms are essential to the efficacy evaluation for treatment after a diagnosis of obstetrical DIC. Therefore, the efficacy evaluation criteria for obstetrical DIC are also defined to enable follow-up of the clinical efficacy of DIC therapy. PMID:24888908

Kobayashi, Takao

2014-06-01

375

Removing Trihalomethane Precursors by Coagulation.  

National Technical Information Service (NTIS)

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 poly...

R. E. Hubel J. K. Edzwald

1987-01-01

376

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

SciTech Connect

Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure {alpha}-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)

2007-06-15

377

Cosmic dust synthesis by accretion and coagulation  

NASA Technical Reports Server (NTRS)

The morphology of grains grown by accretion and coagulation is revaled by a new laboratory method of synthesizing cosmic dust analogs. Submicron carbon particles, grown by accretion of carbon atoms from a gas, have a spherical shape with a cauliflower-like surface and an internal micro-structure of radial columns. This shape is probably common for grains grown by accretion at a temperature well below the melting point. Coagulated grains, consisting of spheres that collided to form irregular strings, were also synthesized. Another shape we produced had a bumpy non- spherical morphology, like an interplanetary particle collected in the terrestrial stratosphere. Besides these isolated grains, large spongy aggregates of nanometer-size particles were also found for various experimental conditions. Grains were synthesized using ions to sputter a solid target, producing an atomic vapor at a low temperature. The ions were provided by a plasma, which also provided electrostatic levitation of the grains during their growth. The temporal development of grain growth was studied by extinguishing the plasma after various intervals.

Praburam, G.; Goree, J.

1995-01-01

378

Microfluidics and coagulation biology.  

PubMed

The study of blood ex vivo can occur in closed or open systems, with or without flow. Microfluidic devices, which constrain fluids to a small (typically submillimeter) scale, facilitate analysis of platelet function, coagulation biology, cellular biorheology, adhesion dynamics, and pharmacology and, as a result, can be an invaluable tool for clinical diagnostics. An experimental session can accommodate hundreds to thousands of unique clotting, or thrombotic, 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 generated on a device using a single perfusion pump. Microfluidics facilitated both the determination of intraluminal thrombus permeability and the discovery that platelet contractility can be activated by a sudden decrease in flow. Microfluidic devices are ideal for multicolor imaging of platelets, fibrin, and phosphatidylserine and provide a human blood analog to 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; McCarty, Owen J T; Diamond, Scott L

2013-01-01

379

Direct solid analysis of powdered tungsten carbide hardmetal precursors by laser-induced argon spark ablation with inductively coupled plasma atomic emission spectrometry.  

PubMed

The potential of the laser-induced argon spark atomizer (LINA-Spark atomizer) coupled with ICP-AES as a convenient device for direct analysis of WC/Co powdered precursors of sintered hardmetals was studied. The samples were presented for the ablation as pressed pellets prepared by mixing with powdered silver binder containing GeO2 as internal standard. The pellets were ablated with the aid of a Q-switched Nd:YAG laser (1064 nm) focused 16 mm behind the target surface with a resulting estimated power density of 5 GW cm(-2). Laser ablation ICP-AES signals were studied as a function of ablation time, and the duration of time prior to measurement (pre-ablation time) which was necessary to obtain reliable results was about 40 s. Linear calibration plots were obtained up to 10% (m/m) Ti, 9% Ta and 3.5% Nb both without internal standardization and by using germanium as an added internal standard or tungsten as a contained internal standard. The relative uncertainty at the centroid of the calibration line was in the range from +/- 6% to +/- 11% for Nb, Ta and Ti both with and without internal standardisation by Ge. A higher spread of points about the regression was observed for cobalt for which the relative uncertainty at the centroid was in the range from +/- 9% to +/- 14%. Repeatability of results was improved by the use of both Ge and W internal standards. The lowest determinable quantities calculated for calibration plots were 0.060% Co, 0.010% Nb, 0.16% Ta and 0.030% Ti with internal standardization by Ge. The LA-ICP-AES analyses of real samples led to good agreement with the results obtained by solution-based ICP determination with a relative bias not exceeding 10%. The elimination of the dissolution procedure of powdered tungsten (Nb, Ta, Ti) carbide is the principal advantage of the developed LA-ICP-AES method. PMID:14564441

Holá, Markéta; Kanický, Viktor; Mermet, Jean-Michel; Otruba, Vítezslav

2003-12-01

380

Analysis of the Mid-Infrared Spectrum of the Exhaust Gas From an Atmospheric Pressure Plasma Jet (APPJ) Working With an Argon–Air Mixture  

Microsoft Academic Search

The mid-infrared (IR) absorption spectrum of the exhaust gas of an atmospheric pressure plasma jet operated in Ar with the admixture of 0.1% of air has been monitored in the spectral region from 4000 to 750 cm-1. The absorption features of CO2, CO, NO, NO2, N2O, HNO2, and HNO3 were identified using a Fourier transform IR spectrometer combined with a

Andrei V. Pipa; Jürgen Ropcke

2009-01-01

381

Disseminated intravascular coagulation (DIC)  

MedlinePLUS

... underlying cause of DIC. Supportive treatments may include: Plasma transfusions to replace blood clotting factors if a ... Jr, Silberstein LE, et al., eds. Hematology: Basic Principles and Practice . 6th ed. Philadelphia, Pa: Elsevier Saunders; ...

382

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

383

Comparison of coagulation performance and floc properties of a novel zirconium-glycine complex coagulant with traditional coagulants.  

PubMed

A new inorganic-organic hybrid material zirconium-glycine complex (ZGC) was firstly used as a coagulant in a coagulation process to treat Pearl River raw water. Its coagulation performance was compared with commonly used aluminum (Al) coagulants such as aluminum sulfate (Al2(SO4)3) and polyaluminum chloride (PAC), in terms of water quality parameters and floc properties. ZGC coagulation achieved higher removal of turbidity (93.8 %) than other traditional coagulants. Charge neutralization was proven to act as a dominant mechanism during ZGC coagulation. The aggregated flocs with ZGC showed the fastest growth rate and good recovery ability compared with the other coagulants and achieved the largest floc size within 5 min. The ZGC coagulant can decrease the hydraulic retention time and increase removal efficiency. PMID:24499988

Zhang, Zhilin; Wu, Chunde; Wu, Yue; Hu, Caixia

2014-05-01

384

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

385

Electron Energy Distribution Detection in Symmetrically Driven RF Argon Discharge  

Microsoft Academic Search

The electron energy distribution function (EEDF) is measured with a Langmuir probe in a symmetrically driven capacitively coupled rf argon discharge. The distortion of the probe current-voltage characteristics by rf plasma potential fluctuation, which is suppressed by electric circuit resonance among an inductance, the electrode-plasma sheath and the plasma-ground stray capacitances, is finally eliminated by applying the remaining fluctuation to

Takashi Kimura; Kazuyuki Ohe

1993-01-01

386

Electron Energy Distribution Detection in Symmetrically Driven RF Argon Discharge  

NASA Astrophysics Data System (ADS)

The electron energy distribution function (EEDF) is measured with a Langmuir probe in a symmetrically driven capacitively coupled rf argon discharge. The distortion of the probe current-voltage characteristics by rf plasma potential fluctuation, which is suppressed by electric circuit resonance among an inductance, the electrode-plasma sheath and the plasma-ground stray capacitances, is finally eliminated by applying the remaining fluctuation to the probe. The detected EEDF differs from the theoretical one obtained from the Boltzmann equation.

Kimura, Takashi; Ohe, Kazuyuki

1993-08-01

387

Electron energy distribution detection in symmetrically driven RF argon discharge  

NASA Astrophysics Data System (ADS)

The electron energy distribution function (EEDF) is measured with a Langmuir probe in a symmetrically driven capacitively coupled RF argon discharge. The distortion of the probe current-voltage characteristics by RF plasma potential fluctuation, which is suppressed by electric circuit resonance among an inductance, the electrode-plasma sheath and the plasma-ground stray capacitances, is finally eliminated by applying the remaining fluctuation to the probe. The detected EEDF differs from the theoretical one obtained from the Boltzmann equation.

Kimura, Takashi; Ohe, Kazuyuki

1993-08-01

388

Physiological levels of blood coagulation factors IX and X control coagulation kinetics in an in vitro model of circulating tissue factor  

PubMed Central

Thrombosis significantly contributes to cancer morbidity and mortality. The mechanism behind thrombosis in cancer may be circulating tissue factor (TF), as levels of circulating TF are associated with thrombosis. However, circulating TF antigen level alone has failed to predict thrombosis in patients with cancer. We hypothesize that coagulation factor levels regulate the kinetics of circulating TF-induced thrombosis. Coagulation kinetics were measured as a function of individual coagulation factor levels and TF particle concentration. Clotting times increased when pooled plasma was mixed at or above a ratio of 4:6 with PBS. Clotting times increased when pooled plasma was mixed at or above a ratio of 8:2 with factor VII-depleted plasma, 7:3 with factor IX- or factor X-depleted plasmas, or 2:8 with factor II-, V- or VIII-depleted plasmas. Addition of coagulation factors VII, X, IX, V and II to depleted plasmas shortened clotting and enzyme initiation times, and increased enzyme generation rates in a concentration-dependent manner. Only additions of factors IX and X from low-normal to high-normal levels shortened clotting times and increased enzyme generation rates. Our results demonstrate that coagulation kinetics for TF particles are controlled by factor IX and X levels within the normal physiological range. We hypothesize that individual patient factor IX and X levels may be prognostic for susceptibility to circulating TF-induced thrombosis.

Tormoen, Garth W.; Khader, Ayesha; Gruber, Andras; McCarty, Owen J.T.

2013-01-01

389

Physiological levels of blood coagulation factors IX and X control coagulation kinetics in an in vitro model of circulating tissue factor  

NASA Astrophysics Data System (ADS)

Thrombosis significantly contributes to cancer morbidity and mortality. The mechanism behind thrombosis in cancer may be circulating tissue factor (TF), as levels of circulating TF are associated with thrombosis. However, circulating TF antigen level alone has failed to predict thrombosis in patients with cancer. We hypothesize that coagulation factor levels regulate the kinetics of circulating TF-induced thrombosis. Coagulation kinetics were measured as a function of individual coagulation factor levels and TF particle concentration. Clotting times increased when pooled plasma was mixed at or above a ratio of 4:6 with PBS. Clotting times increased when pooled plasma was mixed at or above a ratio of 8:2 with factor VII-depleted plasma, 7:3 with factor IX- or factor X-depleted plasmas, or 2:8 with factor II-, V- or VIII-depleted plasmas. Addition of coagulation factors VII, X, IX, V and II to depleted plasmas shortened clotting and enzyme initiation times, and increased enzyme generation rates in a concentration-dependent manner. Only additions of factors IX and X from low-normal to high-normal levels shortened clotting times and increased enzyme generation rates. Our results demonstrate that coagulation kinetics for TF particles are controlled by factor IX and X levels within the normal physiological range. We hypothesize that individual patient factor IX and X levels may be prognostic for susceptibility to circulating TF-induced thrombosis.

Tormoen, Garth W.; Khader, Ayesha; Gruber, András; McCarty, Owen J. T.

2013-06-01

390

Coagulation tests show significant differences in patients with breast cancer.  

PubMed

Activated coagulation and fibrinolytic system in cancer patients is associated with tumor stroma formation and metastasis in different cancer types. The aim of this study is to explore the correlation of blood coagulation assays for various clinicopathologic factors in breast cancer patients. A total of 123 female breast cancer patients were enrolled into the study. All the patients were treatment naïve. Pretreatment blood coagulation tests including PT, APTT, PTA, INR, D-dimer, fibrinogen levels, and platelet counts were evaluated. Median age of diagnosis was 51 years old (range 26-82). Twenty-two percent of the group consisted of metastatic breast cancer patients. The plasma level of all coagulation tests revealed statistically significant difference between patient and control group except for PT (p?50 years) was associated with higher D-dimer levels (p?=?0.003). Metastatic patients exhibited significantly higher D-dimer values when compared with early breast cancer patients (p?=?0.049). Advanced tumor stage (T3 and T4) was associated with higher INR (p?=?0.05) and lower PTA (p?=?0.025). In conclusion, coagulation tests show significant differences in patients with breast cancer. PMID:24596033

Tas, Faruk; Kilic, Leyla; Duranyildiz, Derya

2014-06-01

391

Quantum well intermixing of multiple quantum wells on InP by argon plasma bombardment and the sputtered-SiO2 film  

NASA Astrophysics Data System (ADS)

A quantum well intermixing process combining inductively-coupled-plasma reactive ion etching (ICP-RIE) and SiO2 sputtering film was investigated for the InGaAsP and InGaAlAs multi-quantum wells (MQWs). Optimal distance is 300-nm-thick for InGaAsP and of 200-nm-thick for InGaAlAs. Between MQWs and the upper cladding by ICP-RIE and bombardment, covering the 300-nm-thick sputtered SiO2 using rapid thermal annealer (RTA) processing resulted in a band-gap blue-shift of 90 nm for InGaAsP and of 60 nm for InGaAlAs.

Chiu, C. L.; Lay, T. S.

2013-08-01

392

ARGON ACTIVATION EXPERIMENT. Addendum 1  

Microsoft Academic Search

Additional irradiated argon measurements for the Aircraft Shield Test ; Reactor (ASTR) and results of the initial studies on the exhaust effluent from ; the dry-pool environment of the 3-Mw Ground Test Reactor (GTR) are reported as an ; addendum to NARF-60-16T. With the ASTR in the 2 pi geometry of Configuration II, ; no detectable amounts of argon-41 were

1961-01-01

393

The effect of sample matrix on electron density, electron temperature and gas temperature in the argon inductively coupled plasma examined by Thomson and Rayleigh scattering  

NASA Astrophysics Data System (ADS)

Spatially-resolved electron temperature ( Te), electron number density ( ne) and gas-kinetic temperature ( Tg) maps of the inductively coupled plasma (ICP) have been obtained for two central-gas flow rates, four heights above the load coil (ALC) and in the presence and absence of interferants with a wide range of first ionization potentials. The radial profiles demonstrate how the directly measured fundamental parameters neTe and Tg can be significantly enhanced and/or depressed with added interferent, depending upon plasma operating conditions and observation region. In general, the magnitude of ne, and Te change is found to be an inverse function of interferent ionization potential; furthermore, ne enhancements in the central channel might be the result of electron redistribution from high to low electron density regions rather than from ionization of the matrix. The large measured increases in ne cannot be attributed solely to matrix ionization, especially when measurement uncertainties and the probable over-estimation in calculated ne, enhancements are taken into account. Changes in ne and Te have been correlated with axial Ca atom and ion emission profiles. A brief review of the mechanisms most likely involved in interelement matrix interferences is given within the context of the present study. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by a disk for the Macintosh computer with data files stored in ASCII format. The main article discusses the scientific aspects of the subject and gives an interpretation of the results contained in the data files.

Hanselman, D. S.; Sesi, N. N.; Huang, M.; Hieftje, G. M.

1994-05-01

394

[Modern coagulation management reduces the transfusion rate of allogenic blood products].  

PubMed

Evaluating the patient's individual bleeding history with a standardized questionnaire, using "point-of-care" - methods for coagulation analyses and providing autologous transfusion techniques are preconditions of a modern coagulation management. Therapy of coagulopathic patients should be based on structured hemotherapy algorithms. Surgical haemostasis and the maintenance of the basic conditions for haemostasis are elementary requirements for an effective therapy. In cases of diffuse bleeding, early antifibrinolytic therapy should be considered. Coagulation factor deficiencies should be corrected "goal-directed" using coagulation factor concentrates. Transfusion of fresh frozen plasma is only indicated in the clinical setting of massive transfusions. DDAVP and transfusion of platelet concentrates are options to optimize primary haemostasis. In cases of on-going bleeding, recombinant activated coagulation factor VII represents an option for "ultima-ratio" therapy. PMID:22744856

Weber, Christian Friedrich

2012-06-01

395

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.

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

396

Magnesium and manganese ions accelerate tissue factor-induced coagulation independently of factor IX.  

PubMed

The purpose of the present study was to assess the effect of magnesium and manganese ions on tissue factor (TF)-induced coagulation and the possible role of factor IX therein. When magnesium chloride or manganese chloride were added in low concentrations to normal human plasma, the human (recombinant) TF-induced coagulation time was shortened. At higher concentrations, magnesium and manganese prolonged the TF-induced coagulation time. Maximum shortening of the coagulation time was obtained at a concentration of 0.5 mmol/l Mn or 2 mmol/l Mg in plasma. Shortening of the TF-induced coagulation time by magnesium and manganese was also observed in factor IX-deficient plasma. A comparison was made between TF preparations from human, rabbit, and bovine brain. The accelerating effect of magnesium was greater with human than with rabbit brain TF. Using bovine brain TF, the clotting time was not shortened by magnesium. Activated factor X-induced coagulation of normal plasma was not accelerated by magnesium. From these experiments, it is inferred that activation of factor X by factor VII-TF can be accelerated by magnesium and manganese ions independently of factor IX. PMID:11994563

van den Besselaar, A M H P

2002-01-01

397

Preoperative methylprednisolone administration maintains coagulation homeostasis in patients undergoing liver resection: importance of inflammatory cytokine modulation.  

PubMed

Alterations in hemostatic parameters are a common finding after major hepatic resection. There is growing evidence that inflammation has a significant role in inducing coagulation disarrangement that follows major surgery. To determine whether preoperative methylprednisolone administration has a protective effect against the development of coagulation disorders, we evaluated the effect of preoperative steroids administration on changes in hemostatic parameters and plasma levels of inflammatory cytokines in patients undergoing liver surgery. Seventy-three patients undergoing liver resection were randomized to a steroid group or to a control group. Patients in the steroid group received 500 mg of methylprednisolone preoperatively. Serum levels of coagulation parameters (prothrombin time, platelets, fibrinogen, plasma fibrin degradation products [D-dimer], antithrombin III) and inflammatory mediators (IL-6 and TNF-alpha) were measured before and immediately after the operation and on postoperative days 1, 2, and 5. Multivariate analysis was performed to identify factors related to the characteristics of the patients and surgery affecting coagulation parameters between the two groups. Decreases in antithrombin III, platelet count and fibrinogen levels, prolongation of prothrombin time, and increases in the plasma fibrin degradation products were significantly suppressed by the administration of methylprednisolone. Cytokines production was also significantly suppressed by the administration of methylprednisolone, and there was significant correlation between plasma levels of cytokines and coagulation alterations. These findings suggest that preoperative methylprednisolone administration inhibits the development of coagulation disarrangements in patients undergoing liver resection, possibly through suppressing the production of inflammatory cytokines. PMID:17577134

Pulitanò, Carlo; Aldrighetti, Luca; Arru, Marcella; Finazzi, Renato; Catena, Marco; Guzzetti, Eleonora; Soldini, Laura; Comotti, Laura; Ferla, Gianfranco

2007-10-01

398

[Coagulation behavior of Al13 species].  

PubMed

Coagulation behavior of Al13 species was examined in synthetic water with high alkalinity and high humic acid concentration from viewpoint of the transformation of Al hydrolysis products during the coagulation process. The results indicated that coagulation efficiency of Al coagulants positively correlated with the content of Al13 in the coagulation process. Aluminum chloride (AlCl3) was more effective than polyaluminum chloride (PACI) in removing turbidity and dissolved organic matter in the synthetic water because AlCl3 could not only generate Al13 species but also function as pH control agent in the coagulation process. During coagulation process pH control can improve coagulation process through regulating Al speciation, and AlCl3 benefited most from pH control. PMID:17304842

Hu, Cheng-zhi; Liu, Hui-juan; Qu, Jiu-hui

2006-12-01

399

Effects of argon, dye, and Nd:YAG lasers on epidermis, dermis, and venous vessels  

SciTech Connect

The aim of the present study, which was performed at the dorsal aspects of the ears of guinea pigs, was to compare effects of different lasers on epidermis, dermis, and small venous vessels. Irradiations were performed with argon, dye, and Nd:YAG lasers. In the first series tissue repair processes were studied after argon laser application. Laser defects were excised after 1, 4, 8, and 14 days and were prepared for routine histological examination. The breadth of epidermal defect and extent of dermal coagulation and occlusion of vessels by thrombus formation were examined histologically. In a second series parameters of irradiation (ie, exposure time, laser power) of the three different lasers were changed systematically. Laser-induced morphological tissue changes could be best observed 24 hours after irradiation. Each of the lasers led to occlusion of vessels by thrombus formation and also coagulated epidermis and dermis. The extent of dermal and epidermal coagulation was less pronounced after dye laser application. Using short exposure times it was possible to reduce the extent of epidermal damage caused by argon and Nd:YAG lasers. Only 50-msec dye laser pulses led to intravascular thrombus formation without epidermal and dermal damage.

Landthaler, M.; Haina, D.; Brunner, R.; Waidelich, W.; Braun-Falco, O.

1986-01-01

400

Populations of metastable and resonant argon atoms in radio frequency magnetron plasmas used for deposition of indium-zinc-oxide films  

SciTech Connect

This work reports optical absorption spectroscopy measurements of the number density of Ar atoms in resonant ({sup 3}P{sub 1}, {sup 1}P{sub 1}) and metastable ({sup 3}P{sub 2}, {sup 3}P{sub 0}) states in rf magnetron sputtering plasmas used for the deposition of ZnO-based thin films. While the density of Ar {sup 3}P{sub 2} and {sup 3}P{sub 0} was fairly independent of pressure in the range of experimental conditions investigated, the density of Ar {sup 3}P{sub 1} and {sup 1}P{sub 1} first sharply increased with pressure and then reached a plateau at values close to those of the {sup 3}P{sub 2} and {sup 3}P{sub 0} levels at pressures above about 50 mTorr. At such pressures, ultraviolet radiation from resonant states becomes trapped such that these levels behave as metastable states. For a self-bias voltage of -115 V and pressures in the 5-100 mTorr range, similar number densities of Ar resonant and metastable atoms were obtained for Zn, ZnO, and In{sub 2}O{sub 3} targets, suggesting that, over the range of experimental conditions investigated, collisions between these excited species and sputtered Zn, In, and O atoms played only a minor role on the discharge kinetics. The metastable-to-ground state number density ratios were also fitted to the predictions of a global model using the average electron temperature, T{sub e}, as the only adjustable parameter. For all targets examined, the values of T{sub e} deduced from this method were in excellent agreement with those obtained from Langmuir probe measurements.

Maaloul, L.; Morel, S.; Stafford, L. [Departement de Physique, Universite de Montreal, Montreal, Quebec, H3C 3J7 (Canada)

2012-03-15

401

Evaluation and application of argon and helium microstrip plasma for the determination of mercury by the cold vapor technique and optical emission spectrometry.  

PubMed

The suitability of a 2.45-GHz atmospheric pressure, low-power microwave microstrip plasma (MSP) operated with Ar and He for the determination of Hg by continuous-flow cold vapor (CV) generation, using SnCl2/HCl as the reducing agent, and optical emission spectrometry (OES) using a small CCD spectrometer was studied. The areas of stability for a discharge in the Ar and in the He MSP enclosed in a cylindrical channel in a quartz wafer were investigated. The excitation temperatures as measured for discharge gas atoms (Ar I, He I), and the electron number densities at 35-40 W and 15-400 mL min(-1) were found to be at the order of 3,200-5,500 K and 0.8x10(14)-1.6x10(14) cm(-3), respectively. The relative intensity of the Hg I 253.6-nm line and the signal-to-background ratio as a function of the forward power (35-40 W) as well as of the flow rate of the working gas (15-400 mL min(-1)) were evaluated and discussed. For the selected measurement conditions, the Ar MSP was established to have the lower detection limit for Hg (0.6 ng mL(-1)) compared with the He MSP. The linearity range is up to 300 ng mL(-1) and the precision is on the order of 1-3%. With the optimized CV Ar MSP-OES method a determination of Hg in spiked domestic and natural waters at concentration levels of 20-100 microg L(-1) and an accuracy of 1-4% could be performed. In an NIST domestic sludge standard reference material, Hg (3.64 microg g(-1)) could be determined with a relative standard deviation of 4% and an agreement better than 4%. PMID:17323052

Jiménez Zapata, Israel; Pohl, Pawel; Bings, Nicolas H; Broekaert, José A C

2007-08-01

402

Application of psyllium husk as coagulant and coagulant aid in semi-aerobic landfill leachate treatment  

Microsoft Academic Search

Landfill leachate is a heavily polluted and a likely hazardous liquid that is produced as a result of water infiltration through solid wastes generated industrially and domestically. This study investigates the potential of using psyllium husk as coagulant and coagulant aid for the treatment of landfill leachate. Psyllium husk has been tested as primary coagulant and as coagulant aid with

Yasir A. J. Al-Hamadani; Mohd Suffian Yusoff; Muhammad Umar; Mohammed J. K. Bashir; Mohd Nordin Adlan

2011-01-01

403

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

404

Treatment of tannery wastewater by chemical coagulation  

Microsoft Academic Search

The objective of this study was to develop a treatment system that can effectively reduce the concentration of pollutants in tannery wastewater to environmentally acceptable levels and that can greatly reduce the cost of discharging the effluents. Aluminium sulphate and ferric chloride were used as a coagulant in the process. The influence of pH and coagulant dosages on the coagulation

Z Song; C. J Williams; R. G. J Edyvean

2004-01-01

405

An investigation into an indigenous natural coagulant  

Microsoft Academic Search

Coagulants play an important role in the treatment or water and waste water, and the treatment and disposal of sludge. Aluminum sulfate, alum, is the common chemical coagulant used in the process of coagulation here in Iraq and other middle eastern countries. Recently there have been many rumours of the possible link between high levels of residual aluminum and several

Edham M. Shokralla

1996-01-01

406

Photoacoustic measurement of iron in composite coagulant  

Microsoft Academic Search

Iron concentrations of composite coagulant powders were measured by means of the photoacoustic effect. The onset of photoacoustic signal saturation for iron in the powders was 5 wt.%. This problem was solved by adding one of the components of the composite coagulant as a diluent to the samples. Based on the findings of this research, photoacoustic response of composite coagulant

Maohong Fan; Robert Brown; Shih-Wu Sung

2003-01-01

407

Scaling dynamics of aerosol coagulation  

NASA Astrophysics Data System (ADS)

A combination of static and quasielastic light scattering and the theory of scaling solutions to Smoluchowski's equation was used to determine the absolute coagulation rate K0' and kernel homogeneity ? of a coagulating liquid-drop aerosol. Droplet sizes ranged from 0.23 to 0.42 ?m, implying Knudsen numbers in the range 0.26 and 0.14. The temporal evolution of the number concentration M0 and the modal radius rM of an assumed zeroth-order log-normal distribution showed near-power-law behavior similar to that predicted by the scaling theory. From the temporal scaling behavior of M0(t) and rM(t), the absolute coagulation rate was calculated. The coagulation rates from each method were in good agreement. The rate also agreed well with theory that corrected the Brownian rate, good for the continuum regime, by the average Cunningham correction factor. In addition, the time dependence of the moments M0 and rM, hence the determination of K0', was in good agreement with a real-time numerical solution of Smoluchowski's equation for initial conditions analogous to our experimental ones.

Olivier, B. J.; Sorensen, C. M.; Taylor, T. W.

1992-04-01

408

Hemostasis and Coagulation: Theoretical Concepts.  

National Technical Information Service (NTIS)

The review cites leading articles which deal directly with the formation of theories of coagulation as they exist today. Many of the papers cited were written because of a search for the cause and cure of hemophilia; therefore, this subject is dealt with ...

J. D. Bairrington

1966-01-01

409

Coagulation optimization for low temperature and low turbidity source water using combined coagulants: a case study  

Microsoft Academic Search

Coagulation optimization using coagulants of ferric chloride (FeCl3), polymer–polyaluminum ferric chloride (PAFC) and their combinations (FeCl3\\/PAFC) was evaluated by performing jar tests for treating source water with low temperature (<10°C) and low turbidity (1.5–8 NTU) i,n a typical North-China water treatment plant (WTP), Tanggu WTP. The results indicated that compared to single coagulant, the combined coagulants showed superior coagulation performance

Inchio Lou; Shuyan Gong; Xiangjun Huang; Yanjin Liu

2012-01-01

410

Experiments with a Large Sized Hollow Cathode Discharge Fed with Argon, Part 2.  

National Technical Information Service (NTIS)

Results of measurements made on the positive column of a large sized hollow cathode discharge in argon are presented. The plasma is in a stationary state and fully ionized (though charge exchange collisions with neutral particles are still of importance)....

F. Boeschoten D. J. Kleijn R. Komen W. F. H. Merck A. F. C. Sens

1975-01-01

411

Association of Coagulation Activation with Clinical Complications in Sickle Cell Disease  

Microsoft Academic Search

BackgroundThe contribution of hypercoagulability to the pathophysiology of sickle cell disease (SCD) remains poorly defined. We sought to evaluate the association of markers of coagulation and platelet activation with specific clinical complications and laboratory variables in patients with SCD.Design and MethodsPlasma markers of coagulation activation (D-dimer and TAT), platelet activation (soluble CD40 ligand), microparticle-associated tissue factor (MPTF) procoagulant activity and

Kenneth I. Ataga; Julia E. Brittain; Payal Desai; Ryan May; Susan Jones; John Delaney; Dell Strayhorn; Alan Hinderliter; Nigel S. Key

2012-01-01

412

Bias formation in a pulsed radiofrequency argon discharge  

Microsoft Academic Search

A one dimensional (1D) particle-in-cell (PIC) computer simulation has been used in conjunction with a small experimental plasma reactor, to investigate the effects of pulsing on a low pressure, capacitively coupled, rf argon plasma. In particular this article investigates the time-constants involved in the development and evolution of the bias voltage in asymmetric reactor geometry. Surprisingly, the charging time for

H. B. Smith; C. Charles; R. W. Boswell; H. Kuwahara

1997-01-01

413

Clinical and prognostic significance of coagulation assays in melanoma.  

PubMed

The activation of coagulation and fibrinolysis is frequently found among cancer patients. Such tumors are considered to be associated with a higher risk of invasion, metastases, and eventually worse outcome. The aim of this study is to explore the clinical and prognostic value of blood coagulation tests for melanoma patients. Pretreatment blood coagulation tests including prothrombin time (PT), activated partial thromboplastin time (APTT), prothrombin activity (PTA), international normalized ratio (INR), D-dimer (DD), fibrinogen (F) levels, and platelet (PLT) counts were carried out. This prospective study included 61 melanoma patients [stage I-II (n=10), stage III (n=14), stage IV (n=37), M1c (n=26) disease], and 50 healthy controls. It included 34 (56%) men, median age 53 years, range 16-88 years. Over half of the patients (54%) were in the metastatic stage and most of them (70%) had M1c. The plasma level of pretreatment blood coagulation tests including DD, F, APTT, INR levels, and PLT counts showed a statistically significant difference between the patient and the control group (P<0.001 for all, but P=0.049 for INR). The levels of INR, DD, F, and PLT counts were higher and APTT was lower in the melanoma group, whereas the PT and PTA levels did not show any significant difference. There was a significant association between PT, PTA, INR, and PLT levels and the age of the patient. Patients with node metastasis in M0 disease had higher levels of PTA and PLT counts (P=0.002 and 0.048, respectively) and lower levels of PT and INR (P=0.056 and 0.046, respectively). The M1c patients tended to have higher plasma F levels (437 vs. 297 mg/dl, P=0.055) than M1a and M1b patients. The 1-year survival rate for all patients was 70%. In association with distant metastasis, advanced metastatic stage (M1c), elevated lactate dehydrogenase, and erythrocyte sedimentation rate, only elevated plasma F levels had a significantly adverse effect on survival among the coagulation parameters (P=0.031). The 1-year survival rates for patients with high and normal F levels were 58 and 88%, respectively. In conclusion, changes in the coagulation-fibrinolytic system are often present in melanoma and elevation in the plasma F level is associated with decreased survival. PMID:22889867

Tas, Faruk; Ciftci, Rumeysa; Kilic, Leyla; Bilgin, Elif; Keskin, Serkan; Sen, Fatma; Yildiz, Ibrahim; Yasasever, Vildan

2012-10-01

414

Study of fluid mechanical helium argon ion laser  

NASA Technical Reports Server (NTRS)

An approach to an argon ion laser based on gasdynamic techniques is presented. Improvement in efficiency and power output are achieved by eliminating high heat rejection problems and plasma confinement of the seal-off conventional lasers. The process of producing population inversion between the same energy levels, as in the conventional argon ion laser, has been divided into two phases by separating each other from the processes of ionization and subsequent excitation. Line drawings and graphs are included to amplify the theoretical presentation.

1972-01-01

415

Differential inhibitory effects of humic acids on coagulation systems of human blood  

NASA Astrophysics Data System (ADS)

The present study demonstrated a strong inhibition of the intrinsic pathway of blood coagulation, when 10 µg of humic acid was added to 0.1 ml citrated plasma. An effect on the extrinsic coagulation system was only obtained after addition of more than 30 µg per 0.1 ml plasma, and was confined to a slight increase in the coagulation time. During determination of the thrombin time, humic acid, at concentrations above 40 µg per 0.1 ml plasma, acted like an antithrombin, by means of a sudden inactivation of thrombin. The humic acids were characterized by infrared spectroscopy. Humic acids were purified using a dialyzer as applied for urea clearance in nephrological therapy. The application of this method is novel.

Kübler, Helga

416

A `triangle' of interconnected coagulation models  

NASA Astrophysics Data System (ADS)

A number of new coagulation models depending on a parameter is derived. The dependence is considered in two different ways. If the parameter takes its maximal value then in the first case we obtain a new discrete kinetic equation. We demonstrate that its continuous version is simply the Oort-Hulst's coagulation model. In the second case, the maximum of the corresponding parameter yields the Smoluchowski coagulation equation. At the minimal values of both parameters we arrive at another new kinetic equation. These three models form a `triangle' connecting the two known coagulation equations `situated' in its vertexes (Smoluchowski and Oort-Hulst equations) via an alteration of the parameters. Also, a comparative analysis of these three models is presented. As an advantage of the Oort-Hulst approach we compute the coagulation front and establish a connection between the infringement of the mass conservation law and convergence of the coagulation front to infinity.

Dubovski, P. B.

1999-02-01

417

Insights into platelet-based control of coagulation.  

PubMed

The coagulation process is activated by tight control mechanisms, in which platelets play prominent and unique roles. In thrombosis and hemostasis, activated platelets regulate the coagulation system in various ways: by exposing a phosphatidylserine surface for thrombin formation, by supporting fibrin formation, and by regulating the retraction of a fibrin clot. In this review we discuss the involvement of platelet receptors, other membrane proteins, downstream signaling proteins, cytoskeleton-linked proteins and plasma proteins in these procoagulant functions. Studies with both genetically modified mice and pharmacological inhibitors indicate that, for collagen-adhered platelets, in part common signaling pathways lead to phosphatidylserine exposure, generation of thrombin and fibrin, and retraction of the fibrin clot. However, prolonged Ca(2+) elevation leads to thrombin generation, whereas integrin-dependent signaling stimulates fibrin clot retraction. Contact-dependent signaling pathways, triggered by homotypic platelet-platelet interactions, act in particular via the integrin route. © 2014 Elsevier Ltd. All rights reserved. PMID:24862135

de Witt, Susanne M; Verdoold, Remco; Cosemans, Judith M E M; Heemskerk, Johan W M

2014-05-01

418

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

419

Sonoluminescing Air Bubbles Rectify Argon  

NASA Astrophysics Data System (ADS)

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.

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

1997-02-01

420

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

421

Interaction between Paracoccidioides brasiliensis conidia and the coagulation system: involvement of fibrinogen.  

PubMed

The infectious process starts with an initial contact between pathogen and host. We have previously demonstrated that Paracoccidioides brasiliensis conidia interact with plasma proteins including fibrinogen, which is considered the major component of the coagulation system. In this study, we evaluated the in vitro capacity of P. brasiliensis conidia to aggregate with plasma proteins and compounds involved in the coagulation system. We assessed the aggregation of P. brasiliensis conidia after incubation with human serum or plasma in the presence or absence of anticoagulants, extracellular matrix (ECM) proteins, metabolic and protein inhibitors, monosaccharides and other compounds. Additionally, prothrombin and partial thromboplastin times were determined after the interaction of P. brasiliensis conidia with human plasma. ECM proteins, monosaccharides and human plasma significantly induced P. brasiliensis conidial aggregation; however, anticoagulants and metabolic and protein inhibitors diminished the aggregation process. The extrinsic coagulation pathway was not affected by the interaction between P. brasiliensis conidia and plasma proteins, while the intrinsic pathway was markedly altered. These results indicate that P. brasiliensis conidia interact with proteins involved in the coagulation system. This interaction may play an important role in the initial inflammatory response, as well as fungal disease progression caused by P. brasiliensis dissemination. PMID:23827999

Tamayo, Diana; Hernández, Orville; Muñoz-Cadavid, Cesar; Cano, Luz Elena; González, Angel

2013-06-01