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Sample records for argon plasma coagulation

  1. Coagulation of Dust Particles in Argon Plasma of RF Discharge

    SciTech Connect

    Mankelevich, Yu. A.; Olevanov, M. A.; Pal, A. F.; Rakhimova, T. V.; Ryabinkin, A. N.; Serov, A. O.; Filippov, A. V.

    2008-09-07

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

  2. Endobronchial Schwannoma Treated by Rigid Bronchoscopy with Argon Plasma Coagulation

    PubMed Central

    Lee, Bo Ram; Choi, Yoo Duk; Kim, Yu Il; Lim, Sung Chul

    2012-01-01

    Primary endobronchial schwannomas are extremely rare tumors that originate from Schwann cells. We report a case of primary endobronchial schwannoma. A 44-year-old woman, without respiratory symptoms, was presented with a nodule in the left main bronchus on her chest computed tomography scan. The nodule was removed by a rigid bronchoscopy with argon plasma coagulation. Biopsy confirmed the diagnosis of schwannoma. There was no recurrence during her 4-month follow-up. PMID:23166551

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

    PubMed Central

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

    2014-01-01

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

  4. Gas embolism following bronchoscopic argon plasma coagulation: a case series.

    PubMed

    Reddy, Chakravarthy; Majid, Adnan; Michaud, Gaetane; Feller-Kopman, David; Eberhardt, Ralph; Herth, Felix; Ernst, Armin

    2008-11-01

    Thermal ablation using argon plasma coagulation (APC) is a commonly used modality in the bronchoscopic management of central airway obstruction and hemoptysis. In experienced hands, APC is considered to be a relatively safe tool. Reported complications associated with APC use are rare and include hemorrhage, airway perforation, or airway fires. Systemic gas embolism has been reported with APC during laparoscopic hepatic surgeries, and we have reported one case of systemic gas embolism with cardiovascular collapse in the past. We now report the first case series of systemic, life-threatening gas embolism occurring as a complication of bronchoscopic application of APC. PMID:18988782

  5. Coagulation of dust grains in the plasma of an RF discharge in argon

    SciTech Connect

    Mankelevich, Yu. A.; Olevanov, M. A.; Pal', A. F.; Rakhimova, T. V.; Ryabinkin, A. N.; Serov, A. O.; Filippov, A. V.

    2009-03-15

    Results are presented from experimental studies of coagulation of dust grains of different sizes injected into a low-temperature plasma of an RF discharge in argon. A theoretical model describing the formation of dust clusters in a low-temperature plasma is developed and applied to interpret the results of experiments on the coagulation of dust grains having large negative charges. The grain size at which coagulation under the given plasma conditions is possible is estimated using the developed theory. The theoretical results are compared with the experimental data.

  6. Use of endoscopic-assisted argon plasma coagulation for the treatment of colonic vascular ectasia (angiodysplasia) in an adult dog.

    PubMed

    Harris, Autumn N; Armentano, Robert A; Torres, Ahmira R; Gallagher, Alexander E

    2016-03-01

    CASE DESCRIPTION A 10-year-old neutered male mixed-breed dog was evaluated for a 5-year history of intermittent hematochezia and chronic anemia that were unresponsive to medical treatment. CLINICAL FINDINGS Colonoscopy revealed multifocal areas of coalescing tortuous mucosal blood vessels throughout the colon and rectum. Colonic vascular ectasia (angiodysplasia) was diagnosed on the basis of the endoscopic appearance of the lesions. TREATMENT AND OUTCOME The dog failed to respond to traditional medical treatments for colonic vascular ectasia and required multiple plasma and blood transfusions. The dog received 4 endoscopic-assisted argon plasma coagulation treatments, which resulted in long-term resolution of gastrointestinal hemorrhage. Colonic perforation occurred during the third argon plasma coagulation treatment. The perforation was surgically repaired. The dog remained free from clinical signs of colonic vascular ectasia for > 1 year after the third argon plasma coagulation treatment and was euthanized because of clinical deterioration associated with progressive heart disease. CLINICAL RELEVANCE Endoscopic-assisted argon plasma coagulation treatment is a novel treatment for dogs with colonic vascular ectasia and provided long-term resolution of clinical signs for the dog of this report. In human patients, complications associated with endoscopic-assisted argon plasma coagulation treatment include colonic perforation, which also occurred in the dog of this report. PMID:26885595

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

    PubMed

    Su, Pei-Yuan; Yen, Hsu-Heng

    2010-02-01

    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

  8. Tracheomediastinal Fistula in a Patient With Lung Adenocarcinoma and Its Treatment With Argon Plasma Coagulation

    PubMed Central

    Ucer, Mehtap; Ordu, Cetin; Pilanc?, Kezban Nur; Dalar, Levent

    2014-01-01

    Abstract Tracheomediastinal fistula is a rare complication that occurs during the course of lung cancer. The fistula connects the airways to the mediastinum and is often associated with lymphoma. Clinical data on tracheomediastinal fistulas are limited to case reports. Tracheal stenting, pericardial and omental patch closure, and muscle flap closure can be performed to repair such fistulas. We herein report a case of tracheomediastinal fistula in a 47-year-old man. The main symptoms were shortness of breath and a feeling of fullness in the neck. Thoracic magnetic resonance imaging revealed an approximately 57??16??20 mm multiloculated cystic lesion with air density located in the upper mediastinum of the right paratracheal region and a fine fistula tract at this level. The main diagnosis was primary lung adenocarcinoma-related mediastinal lymphadenomegaly with a tracheomediastinal fistula. The patient underwent fistula opening on the trachea, which was then coagulated and sealed using argon plasma coagulation. The patient is currently asymptomatic and doing well 8 months after the intervention. PMID:25415672

  9. Argon plasma coagulation and the future applications for dual-mode endoscopic probes.

    PubMed

    Canady, Jerome; Wiley, Kimberly; Ravo, Biagio

    2006-01-01

    Argon plasma coagulation (APC) is a thermoablative technique increasingly being used in endoscopy. Since its introduction, the flexible APC probe has been employed by endoscopists throughout the world. APC has helped change the endoscopic management of many gastrointestinal (GI) diseases, including hemorrhagic proctitis, watermelon stomach, bleeding peptic ulcer, and colonic varices. Endoscopists and surgeons are creatively combining standard and new electrosurgical techniques with APC. For instance, APC used in combination with piecemeal polypectomy, endoscopic mucosal resection, balloon dilatation for strictures, and plasma welding of bleeding vessels after sclerotherapy injection are among the recent innovative techniques reported. Other emerging innovations using APC that are being considered include endoscopic en bloc resection of mucosal and submucosal tumors of the GI tract, endoscopic mucosal resection supplemented with APC for high-grade dysplasia and early GI cancers, endoscopic repair of anastomotic strictures, and welding GI fistula tracts. As such, endoscopists require more efficient and cost-effective multifunctional thermoablative probes. This review discusses the development and the potential application of dual-mode plasma endoscopic probes in fulfilling these emerging needs. PMID:16520707

  10. Usefulness of Rigid Bronchoscopic Intervention Using Argon Plasma Coagulation for Central Airway Tumors

    PubMed Central

    Lee, Bo-Ram; Oh, In-Jae; Lee, Ho-Sung; Ban, Hee-Jung; Kim, Kyu-Sik; Kim, Yu-Il; Lim, Sung-Chul; Kim, Young-Chul; Park, Yong-Wook

    2015-01-01

    Objectives Argon plasma coagulation (APC) is a noncontact form of electrocautery that utilizes ionized argon as the electrical current. A rigid bronchoscopic use of APC for the management of central airway obstruction could be safe and rapidly effective. This study evaluated the usefulness of rigid bronchoscopy with APC for the management of central airway obstructions due to benign or malignant tumors. Methods Twenty patients with obstructing central airway tumors were retrospectively reviewed from February 2008 to February 2013 at Chonnam National University Hospital. All patients received rigid bronchoscopic tumor removal under general anesthesia. APC was applied before and after tumor removal. Results The median age of patients was 59 years (interquartile range [IQR], 51 to 67 years) and 70% were female. The causes of airway obstruction included malignancy (n=8) and benign tumor (n=12). Airway tumors comprised intraluminal lesions (n=11, 55%) and mixed intraluminal/extraluminal lesions (n=9, 45%). The median tumor size was 15 mm (IQR, 10 to 18 mm). The median degree of airway obstruction was significantly reduced after intervention (90% [IQR, 88% to 96%] vs. 10% [IQR, 0% to 20%], P<0.001). The median American Thoracic Society dyspnea grade (3 [IQR, 1 to 4] vs. 1 [IQR, 0 to 1], P<0.001) and forced expiratory volume in one second (1.03 L [IQR, 0.52 to 1.36 L] vs. 1.98 L [IQR, 1.57 to 2.64 L], P=0.004) were significantly improved after intervention. There were no procedure-related acute complications and deaths. Conclusion Rigid bronchoscopy with APC is an effective and safe procedure to alleviate central airway obstruction caused by tumors. PMID:26622961

  11. Successful Treatment of Severe Spontaneous Periampullary Bleeding with Argon Plasma Coagulation

    PubMed Central

    Abadir, Amir

    2014-01-01

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

  12. Development of hyperplastic polyps following argon plasma coagulation of gastric antral vascular ectasia.

    PubMed

    Shah, Nihar; Cavanagh, Yana; Kaswala, Dharmesh H; Shaikh, Sohail

    2015-01-01

    The etiology of gastric antral vascular ectasia (GAVE) syndrome or gastric hyperplastic polyps (HPs) is not fully understood. We report a case of gastric HP arising in a patient treated with argon plasma coagulation (APC) for GAVE syndrome. Despite unclear etiologic progression, this and previously reported cases suggest a temporal relationship between the treatment of GAVE and HP. A 68-year-old male with a history of coronary artery disease, congestive heart failure and diabetes type II who initially presented with symptomatic anemia 2 weeks after starting aspirin and clopidogrel therapy. Diagnostic esophagogastroduodenoscopy (EGD) demonstrated diffuse GAVE. He was treated with 5 APC treatments, at 6-week intervals, over a 30 weeks period. 16 months after the initial APC treatment, an EGD performed secondary to persistent anemia demonstrated innumerable, large, bleeding polyps in the gastric antrum. Biopsy performed at that time confirmed hyperplastic gastric polyps. It has been proposed that HPs are regenerative lesions that arise at sites of severe mucosal injury. Our patient's treatment of GAVE with APC created significant mucosal injury, resulting in HP. Technique and genetic factors may have promoted hyperplastic changes during the regeneration of mucosa, at sites previously treated with APC. This case highlights the potential progression of GAVE to HP in a patient with persistent anemia after APC therapy. PMID:26283860

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

    PubMed

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

    2014-06-01

    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 cm/s increase of flow and 0.75 0.06 Pa/cm/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

  14. From electrocautery, balloon dilatation, neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser to argon plasma coagulation and cryotherapy.

    PubMed

    Sachdeva, Ashutosh; Pickering, Edward M; Lee, Hans J

    2015-12-01

    Over the past decade, there has been significant advancement in the development/application of therapeutics in thoracic diseases. Ablation methods using heat or cold energy in the airway is safe and effective for treating complex airway disorders including malignant and non-malignant central airway obstruction (CAO) without limiting the impact of future definitive therapy. Timely and efficient use of endobronchial ablative therapies combined with mechanical debridement or stent placement results in immediate relief of dyspnea for CAO. Therapeutic modalities reviewed in this article including electrocautery, balloon dilation (BD), neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation (APC), and cryotherapy are often combined to achieve the desired results. This review aims to provide a clinically oriented review of these technologies in the modern era of interventional pulmonology (IP). PMID:26807284

  15. From electrocautery, balloon dilatation, neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser to argon plasma coagulation and cryotherapy

    PubMed Central

    Pickering, Edward M.; Lee, Hans J.

    2015-01-01

    Over the past decade, there has been significant advancement in the development/application of therapeutics in thoracic diseases. Ablation methods using heat or cold energy in the airway is safe and effective for treating complex airway disorders including malignant and non-malignant central airway obstruction (CAO) without limiting the impact of future definitive therapy. Timely and efficient use of endobronchial ablative therapies combined with mechanical debridement or stent placement results in immediate relief of dyspnea for CAO. Therapeutic modalities reviewed in this article including electrocautery, balloon dilation (BD), neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation (APC), and cryotherapy are often combined to achieve the desired results. This review aims to provide a clinically oriented review of these technologies in the modern era of interventional pulmonology (IP). PMID:26807284

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

    SciTech Connect

    Yeoh, Eric; Tam, William; Schoeman, Mark; Moore, James; Thomas, Michelle; Botten, Rochelle; Di Matteo, Addolorata

    2013-12-01

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

  17. A Case of Recurrent Respiratory Papillomatosis Successfully Removed Via Endoscopic Argon Plasma Coagulation (APC) With No Evidence of Recurrence.

    PubMed

    Wong, J L; Tie, S T; Lee, J; Kannan, S K; Rashid Ali, M R; Ibrahim, A; Abdul Rahman, J A

    2014-08-01

    Recurrent respiratory papillomatosis (RRP) is a benign disease caused by the human papilloma virus (HPV), characterized by the formation of recurrent, epithelial neoplastic lesions in the airways. While benign, they can cause significant airway obstruction in some cases. Difficulties in treatment arise from the recurrent nature of the lesions despite repeated procedures. Other known procedures that result in deep tissue damage also cause unacceptable collateral damage to the underlying airway mucosa. We describe a case of recurrent papillomatosis that was successfully treated with argon plasma coagulation ( APC) when laser and electrocautery ablation had failed in the past. After the papillomatasis was treated with APC, there is no recurrence on repeat scope at 4 months and 9 months after the initial procedure. The procedure was done as a day case and there is no complication from the procedure. The property of the APC that allows it to cause only superficial thermal damage to the tissue makes it a suitable adjunct therapy to the treatment of papillomas, which are usually superficial lesions. PMID:25500852

  18. ENDOSCOPIC PLASMA ARGON COAGULATION IN TREATMENT OF WEIGHT REGAIN AFTER BARIATRIC SURGERY: WHAT DOES THE PATIENT THINK ABOUT THIS?

    PubMed Central

    MARCHESINI, Simone Dallegrave; BARETTA, Giorgio Alfredo Pedroso; CAMBI, Maria Paula Carlini; MARCHESINI, Joo Batista

    2014-01-01

    Background Bariatric surgery, especially Roux-en-Y gastric bypass is an effective treatment for refractory morbid obesity, causing the loss of 75% of initial excess weight. After the surgery, however, weight regain can occur in 10-20% of cases. To help, endoscopic argon plasma coagulation (APC) is used to reduce the anastomotic diameter. Many patients who undergo this treatment, are not always familiar with this procedure and its respective precautions. Aim The aim of this study was to determine how well the candidate for APC understands the procedure and absorbs the information provided by the multidisciplinary team. Method We prepared a questionnaire with 12 true/false questions to evaluate the knowledge of the patients about the procedure they were to undergo. The questionnaire was administered by the surgeon during consultation in the preoperative period. The patients were invited to fill out the questionnaire. Results We found out that the majority learned about the procedure through the internet. They knew it was an outpatient treatment, where the anesthesia was similar to that for endoscopy, and that they would have to follow a liquid diet. But none of them knew that the purpose of this diet was to improve local wound healing. Conclusion Bariatric patients who have a second chance to resume weight loss, need continuous guidance. The internet should be used by the multidisciplinary team to promote awareness that APC will not be sufficient for weight loss and weight-loss maintenance in the long term. Furthermore, there is a need to clarify again the harm of drinking alcohol in the process of weight loss, making its curse widely known. PMID:25409966

  19. Sixteen-year follow-up of Barretts esophagus, endoscopically treated with argon plasma coagulation

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

    2012-01-01

    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 < 0.001) and required more treatment sessions to achieve complete hemostasis (2.4 ± 1.4 versus 1.1 ± 0.1, P < 0.001) than those with angiodysplasia. Univariate analysis demonstrated that age greater than 60 years (odds ratio (OR) = 8.929, P = 0.003), GAVE (OR = 0.021, P < 0.001), and previous radiation therapy (OR = 11.667, P = 0.032) were associated with higher rates of recurrent bleeding. Further multivariate analysis revealed that GAVE was the only independent risk factor for recurrent bleeding after APC treatment (OR = 0.027, P < 0.001). Conclusion Endoscopic hemostasis with APC is a safe treatment modality for both angiodysplasia and vascular ectasia bleeding. The efficacy of APC treatment is greater for angiodysplasia than for vascular ectasia bleeding. GAVE patients have a higher recurrent bleeding rate and may require multiple treatment sessions for sustained hemostasis. PMID:22681987

  1. POST-BARIATRIC SURGERY WEIGHT REGAIN: EVALUATION OF NUTRITIONAL PROFILE OF CANDIDATE PATIENTS FOR ENDOSCOPIC ARGON PLASMA COAGULATION

    PubMed Central

    CAMBI, Maria Paula Carlini; MARCHESINI, Simone Dallegrave; BARETTA, Giorgio Alfredo Pedroso

    2015-01-01

    Background Bariatric surgery is effective treatment for weight loss, but demand continuous nutritional care and physical activity. They regain weight happens with inadequate diets, physical inactivity and high alcohol consumption. Aim To investigate in patients undergoing Roux-Y-of gastroplasty weight regain, nutritional deficiencies, candidates for the treatment with endoscopic argon plasma, the diameter of the gastrojejunostomy and the size of the gastric pouch at the time of treatment with plasma. Methods A prospective 59 patients non-randomized study with no control group undergoing gastroplasty with recurrence of weight and candidates for the endoscopic procedure of argon plasma was realized. The surgical evaluation consisted of investigation of complications in the digestive system and verification of the increased diameter of the gastrojejunostomy. Nutritional evaluation was based on body mass index at the time of operation, in the minimum BMI achieved after and in which BMI was when making the procedure with plasma. The laboratory tests included hemoglobin, erythrocyte volume, ferritin, vitamin D, B12, iron, calcium, zinc and serum albumin. Clinical analysis was based on scheduled follow-up. Results Of the 59 selected, five were men and 51 women; were included 49 people (four men and 44 women) with all the complete data. The exclusion was due to the lack of some of the laboratory tests. Of this total 19 patients (38.7%) had a restrictive ring, while 30 (61.2%) did not. Iron deficiency anemia was common; 30 patients (61.2%) were below 30 with ferritin (unit); 35 (71.4%) with vitamin B12 were below 300 pg/ml; vitamin D3 deficiency occurred in more than 90%; there were no cases of deficiency of protein, calcium and zinc; glucose levels were above 99 mg/dl in three patients (6.12%). Clinically all had complaints of labile memory, irritability and poor concentration. All reported that they stopped treatment with the multidisciplinary team in the first year after the operation. Conclusions The profile of patients submitted to argon plasma procedure was: anastomosis in average with 27 mm; multiple nutritional deficiencies with predominance of iron deficiency anemia; ferritin below 30; vitamin B12 levels below 300 pg/ml; labile memory complaints, irritability and poor concentration. PMID:25861068

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

    PubMed Central

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

    2006-01-01

    Background Many modalities have been used to ablate Barrett's oesophagus (BO). However, long term results and comparative effectiveness are unknown. Aims Our aim was to compare the long term efficacy of achieving complete reversal (endoscopic and histological) between multipolar electrocoagulation (MPEC) and argon plasma coagulation (APC) in BO patients and assess factors influencing successful ablation. Methods Patients with BO, 2–6 cm long, underwent 24 hour pH testing on proton pump inhibitor (PPI) therapy. Patients were then randomised by BO length to undergo ablation with MPEC or APC every 4–8 weeks until endoscopic reversal or maximal of six treatment sessions. Results Thirty five BO patients have been followed for at least two years following endoscopic ablation, 16 treated with MPEC and 19 with APC. There was complete reversal of BO in 24 patients (69%); 75% with MPEC and 63% with APC (p = 0.49). There was no difference in the number of sessions required in the two groups. There was no difference in age, pH results, BO length, PPI dose, or hiatal hernia size between patients with and without complete reversal. One patient developed an oesophageal stricture but there were no major complications such as bleeding or perforation. Conclusions In BO patients treated with MPEC or APC in combination with acid suppression, at long term follow up, complete reversal of BO can be maintained in approximately 70% of patients, irrespective of the technique. There are no predictors associated with achieving complete reversal of BO. Continued surveillance is still indicated in the post ablative setting. As yet, these techniques are not ready for clinical application (other than for high grade dysplasia or early oesophageal adenocarcinoma) and cannot be offered outside the research arena. PMID:16905695

  3. Improvement of Short-Term Outcomes for High-Risk Bleeding Peptic Ulcers With Addition of Argon Plasma Coagulation Following Endoscopic Injection Therapy: A Randomized Controlled Trial.

    PubMed

    Wang, Huay-Min; Tsai, Wei-Lun; Yu, Hsien-Chung; Chan, Hoi-Hung; Chen, Wen-Chi; Lin, Kung-Hung; Tsai, Tzung-Jiun; Kao, Sung-Shuo; Sun, Wei-Chih; Hsu, Ping-I

    2015-08-01

    A second endoscopic method together with injection therapy is recommended to treat high-risk bleeding peptic ulcers. This study investigated whether additional argon plasma coagulation (APC) treatment could influence hemostatic efficacy following endoscopic injection therapy to treat high-risk bleeding ulcers.From October 2010 to January 2012, eligible patients with high-risk bleeding ulcers were admitted to our hospital. They prospectively randomly underwent either APC therapy along with distilled water injection or distilled water injection alone. Episodes of rebleeding were retreated with endoscopic combination therapy. Patients in whom retreatment was ineffective underwent emergency surgery or transarterial embolization (TAE).A total of 116 enrolled patients were analyzed. The hemostatic efficacy in 58 patients treated with APC along with distilled water injection was compared with that in 58 patients treated with distilled water injection alone. The 2 treatment groups were similar with respect to all baseline characteristics. Initial hemostasis was accomplished in 56 patients treated with combined therapy, and 55 patients treated with distilled water injection therapy (97% vs 95%, P?=?0.648). Bleeding recurred in 2 patients treated with combined therapy, and 9 patients treated with distilled water injection (3.6% vs 16%, P?=?0.029). Treatment method was the only independent prognostic factor for recurrent bleeding (odds ratio 0.17; 95% confidence interval 0.03-0.84; P?=?0.029). The 2 groups did not differ significantly in hospital stay, TAE, surgery, and mortality.Endoscopic therapy with APC following distilled water injection is more effective than distilled water injection alone for preventing rebleeding of peptic ulcer. PMID:26266385

  4. Improvement of Short-Term Outcomes for High-Risk Bleeding Peptic Ulcers With Addition of Argon Plasma Coagulation Following Endoscopic Injection Therapy

    PubMed Central

    Wang, Huay-Min; Tsai, Wei-Lun; Yu, Hsien-Chung; Chan, Hoi-Hung; Chen, Wen-Chi; Lin, Kung-Hung; Tsai, Tzung-Jiun; Kao, Sung-Shuo; Sun, Wei-Chih; Hsu, Ping-I.

    2015-01-01

    Abstract A second endoscopic method together with injection therapy is recommended to treat high-risk bleeding peptic ulcers. This study investigated whether additional argon plasma coagulation (APC) treatment could influence hemostatic efficacy following endoscopic injection therapy to treat high-risk bleeding ulcers. From October 2010 to January 2012, eligible patients with high-risk bleeding ulcers were admitted to our hospital. They prospectively randomly underwent either APC therapy along with distilled water injection or distilled water injection alone. Episodes of rebleeding were retreated with endoscopic combination therapy. Patients in whom retreatment was ineffective underwent emergency surgery or transarterial embolization (TAE). A total of 116 enrolled patients were analyzed. The hemostatic efficacy in 58 patients treated with APC along with distilled water injection was compared with that in 58 patients treated with distilled water injection alone. The 2 treatment groups were similar with respect to all baseline characteristics. Initial hemostasis was accomplished in 56 patients treated with combined therapy, and 55 patients treated with distilled water injection therapy (97% vs 95%, P = 0.648). Bleeding recurred in 2 patients treated with combined therapy, and 9 patients treated with distilled water injection (3.6% vs 16%, P = 0.029). Treatment method was the only independent prognostic factor for recurrent bleeding (odds ratio 0.17; 95% confidence interval 0.03–0.84; P = 0.029). The 2 groups did not differ significantly in hospital stay, TAE, surgery, and mortality. Endoscopic therapy with APC following distilled water injection is more effective than distilled water injection alone for preventing rebleeding of peptic ulcer. PMID:26266385

  5. Argon plasma coagulation for the endoscopic treatment of gastrointestinal tumor bleeding: A retrospective comparison with a non-treated historical cohort

    PubMed Central

    Wodak, Stephanie; Gusmon, Carla C; Safatle-Ribeiro, Adriana Vaz; Kawaguti, Fabio Shiguehissa; Baba, Elisa Ryoka; Pennacchi, Caterina MP; Lima, Marcelo Simas; Ribeiro, Ulysses; Maluf-Filho, Fauze

    2015-01-01

    Background The endoscopic use of argon plasma coagulation (APC) to achieve hemostasis for upper gastrointestinal tumor bleeding (UGITB) has not been adequately evaluated in controlled trials. This study aimed to evaluate the efficacy of APC for the treatment of upper gastrointestinal bleeding from malignant lesions. Methods Between January and September 2011, all patients with UGITB underwent high-potency APC therapy (up to 70 Watts). This group was compared with a historical cohort of patients admitted between January and December 2010, when the endoscopic treatment of bleeding malignancies was not routinely performed. Patients were stratified into two categories, grouping the Eastern Cooperative Oncology Group (ECOG) performance status scale: Category I (ECOG 0–2) patients with a good clinical status and Category II (ECOG 3–4) patients with a poor clinical status. Results Our study had 25 patients with UGITB whom underwent APC treatment and 28 patients whom received no endoscopic therapy. The clinical characteristics of the groups were similar, except for endoscopic active bleeding, which was more frequently detected in APC group. We had 15 patients in the APC group whom had active bleeding, and initial hemostasis was obtained in 11 of them (73.3%). In the control group, four patients had active bleeding. There were no differences in 30-day re-bleeding (33.3% in the APC group versus 14.3% in the control group; p = 0.104) and 30-day mortality rates (20.8% in the APC group, versus 42.9% in the control group; p = 0.091). When patients were categorized according to their ECOG status, we found that APC therapy had no impact in re-bleeding and mortality rates (Group I: APC versus no endoscopic treatment: re-bleeding p = 0.412, mortality p = 0.669; Group II: APC versus no endoscopic treatment: re-bleeding p = 0.505, mortality p = 0.580). Hematemesis and site of bleeding located at the esophagus or duodenum were associated with a higher 30-day mortality. Conclusions Endoscopic hemostasis of UGITB with APC has no significant impact on 30-day re-bleeding and mortality rates, irrespective of patient performance status. PMID:26966522

  6. Coagulation of dust particles in a plasma

    NASA Technical Reports Server (NTRS)

    Horanyi, M.; Goertz, C. K.

    1990-01-01

    The electrostatic charge of small dust grains in a plasma in which the temperature varies in time is discussed, pointing out that secondary electron emission might introduce charge separation. If the sign of the charge on small grains is opposite to that on big ones, enhanced coagulation can occur which will affect the size distribution of grains in a plasma. Two scenarios where this process might be relevant are considered: a hot plasma environment with temperature fluctuations and a cold plasma environment with transient heating events. The importance of the enhanced coagulation is uncertain, because the plasma parameters in grain-producing environments such as a molecular cloud or a protoplanetary disk are not known. It is possible, however, that this process is the most efficient mechanism for the growth of grains in the size range of 0.1-500 microns.

  7. Laparoscopic Use of Argon Beam Coagulator in the Management of Endometriosis

    PubMed

    Daniell; McTavish; Kurtz; Tallab

    1994-08-01

    Fifty-five patients with endometriosis in whom argon beam coagulation was used through the laparoscope for coagulation of endometrial lesions, lysis of pelvic adhesions, uterosacral nerve ablation (LUNA) and presacral neurectomy (PSN) were evaluated retrospectively. Thirty patients (54%) had pelvic pain, and 25 patients (46%) presented with pelvic pain and/or infertility. Postoperatively, 29 (72.5%) women showed improvement of pain, 6 (15%) had no change of pain, and in 5 (12.5%) the pain became worse. Seven patients were able to conceive after longstanding infertility, for an early crude pregnancy rate of 28%. Laparoscopic use of argon beam coagulator in the treatment of endometriosis for both pain management and infertility is as effective as other electrosurgical or laser techniques. PMID:9073672

  8. Coagulation Factor XIIIa Substrates in Human Plasma

    PubMed Central

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

    2014-01-01

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

  9. Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas

    SciTech Connect

    Nunomura, Shota; Kondo, Michio; Shiratani, Masaharu; Koga, Kazunori; Watanabe, Yukio

    2008-08-15

    The kinetics of nanoparticle coagulation has been studied in fractionally charged and charge fluctuating dusty plasmas. The coagulation occurs when the mutual collision frequency among nanoparticles exceeds their charging and decharging/neutralization frequency. Interestingly, the coagulation is suppressed while a fraction (several percent) of nanoparticles are negatively charged in a plasma, in which stochastic charging plays an important role. A model is developed to predict a phase diagram of the coagulation and its suppression.

  10. Diamond film growth argon-carbon plasmas

    DOEpatents

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

    1998-01-01

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

  11. Merging of high speed argon plasma jets

    SciTech Connect

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

    2013-01-15

    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.

  12. Contact Activation of Blood Plasma Coagulation

    PubMed Central

    Vogler, Erwin A.; Siedlecki, Christopher A.

    2009-01-01

    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. PMID:19168215

  13. Diamond film growth argon-carbon plasmas

    DOEpatents

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

    1998-12-15

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

  14. Zinc ionization by interaction with argon plasma

    NASA Astrophysics Data System (ADS)

    Kawai, Yoko; Suzuki, Tatsuya; Fujii, Yasuhiko

    1999-11-01

    A low-temperature zinc plasma was generated by secondary ionization using an electron cyclotron resonance argon plasma. The ionization efficiency of zinc samples of the metal, the bromide, and the iodide were examined at different sample crucible temperatures. It was found that the ionization rate of zinc metal is the highest among the tested samples. The observed reaction rate constants icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/>, defined as icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> = nZn+/nZnnAr+ in the present work, are 1.8 10-18 m-3, 1.7 10-19 m-3 and 3.7 10-19 m-3 for zinc metal, zinc bromide, and zinc iodide, respectively. The large reaction constant of zinc metal may be due to the small dissociation energy into atom vapour, compared with the large dissociation energies of the zinc halides.

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

    SciTech Connect

    Singh, Kuldip; Singh, Gurpreet; Sharma, Rohit

    2010-07-15

    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.

  16. Characterization and literature review of bowel perforation injuring using argon beam coagulation

    NASA Astrophysics Data System (ADS)

    Barnes, Kelli S.; Merchel, Renée. A.; Taylor, Kenneth D.

    2015-03-01

    INTRODUCTION: Argon Beam Coagulation (ABC®) technology is used in conjunction with the ConMed ABCFlex® Probe to provide non-contact hemostasis, coagulation, and tissue devitalization during endoscopic procedures. ABC provides a superficial tissue effect; however, there is a risk of bowel perforation. To better understand the settings that lead to perforation, this study reviews the literature and provides an ex vivo characterization of the ABCFlex Probe tissue effect at different settings when used at small distances. METHODS: Depth of thermal tissue effect was characterized to determine the effect of three parameters: power (W), distance from probe tip to tissue (mm) and application duration (s). 3 ABCFlex Probes were used to create 15 samples on ex vivo porcine small intestine for each combination of parameters. The depth of tissue effect for each sample was measured using a light microscope. RESULTS: Depth of tissue effect increases as power and application time increases. An increase of distance from the probe tip to the tissue results in a decrease in depth of tissue effect from a near contact to 1mm distance. Depth of tissue effect doesn't significantly change from 1mm to 3mm distance. CONCLUSION: ABCFlex Probe can be used to achieve hemostasis in endoscopic procedures. Increasing power and application time increases the depth of thermal effect while increasing distance from the probe time to the surface of the tissue decreases the depth of tissue effect.

  17. ECR Plasma Sterilisation, Argon and Nitrogen Treated Plasma

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

    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.

  18. Modeling of an argon cascaded arc plasma by ANSYS FLUENT

    NASA Astrophysics Data System (ADS)

    Wei, Guodong; Qi, Xin; Yang, Lei

    2014-04-01

    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.

  19. Properties of radio-frequency heated argon confined uranium plasmas

    NASA Technical Reports Server (NTRS)

    1976-01-01

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

  20. On the OES line-ratio technique in argon and argon-containing plasmas

    NASA Astrophysics Data System (ADS)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2014-11-01

    Optical emission spectroscopy is used to investigate capacitively coupled argon and argon-hydrogen-silane plasmas. The argon collisional-radiative model (CRM) used to extract the electron density and temperature from the spectra is presented. The electron energy distribution function, which is an input parameter to the model, is discussed in detail. Its strong variation with pressure is found to significantly influence the results for the (effective) temperature. For the analysis of the spectra the common line-ratio technique is applied. Special attention is paid to the choice of lines and a pair of line-ratios for optimum accuracy is suggested. For the argon gas mixture at high partial pressure of the admixed molecular gases the CRM reduces to a corona-like model, extended by a quenching term. The line-ratio method is found to fail under these conditions due to the strong depopulation of the argon 1s states. As a consequence, individual line intensities have to be used and an absolute calibration is required. An easy calibration method, which relies on the results obtained by the line-ratio method in pure argon, is proposed and applied.

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

    SciTech Connect

    Kakati, B. Kausik, S. S.; Saikia, B. K.; Bandyopadhyay, M.; Saxena, Y. C.

    2014-10-28

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

  2. Behavior of Excited Argon Atoms in Inductively Driven Plasmas

    SciTech Connect

    HEBNER,GREGORY A.; MILLER,PAUL A.

    1999-12-07

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

  3. COAGULATION

    EPA Science Inventory

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

  4. Supersonic Argon Flow In An Arc Plasma Source

    SciTech Connect

    Izrar, B.; Dudeck, M.; Andre, P.; Elchinger, M. F.; Aubreton, J.

    2006-01-15

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

  5. Equation of state of partially ionized argon plasma

    SciTech Connect

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

    2011-11-15

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

  6. Resonance broadening of argon lines in a micro-scaled atmospheric pressure plasma jet (argon ?APPJ)

    NASA Astrophysics Data System (ADS)

    Pipa, A. V.; Ionikh, Yu. Z.; Chekishev, V. M.; Dnnbier, M.; Reuter, S.

    2015-06-01

    Optical emission from atmospheric pressure micro-jet operating with pure argon (argon ?APPJ) flow has been detected with a moderate resolution spectrometer. Large broadening of the several argon (Ar) lines has been observed in the near infrared spectral region. This effect was attributed to resonance broadening of the s2 (Paschen notation) level in 3p54s configuration. In the present work, corresponding line profiles are suggested for plasma diagnostics. For this, a general case of resonance broadening coefficient of noble gases is discussed. As broadening reflects the Ar density, and the static gas pressure of the jet is in equilibrium with the ambient, the local gas temperature can be inferred. An estimation of gas temperature from the width of the 750 nm Ar line is in agreement with rotational temperature of OH radicals determined from the A2?+ ? X2? (0, 0) band. At low temperatures (300-600 K) and at partial Ar pressure near atmospheric, the resonance width of the suggested lines is very sensitive to small temperature variations. High temperature sensitivity and large width make the resonance broadened lines very attractive for diagnostics of low temperature discharges at elevated pressure, e.g., as they are used in plasma-medicine.

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

    SciTech Connect

    Bang, Jin-Young; Han, Duksun; Cho, Sung-Won; Chung, Chin-Wook

    2012-04-16

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

  8. Dynamics of axial plasma jets in neon and argon plasma focus discharges

    NASA Astrophysics Data System (ADS)

    Baronova, E. O.; Vovchenko, E. D.; Maiorov, A. N.; Nikulin, V. Ya; Silin, P. V.; Stepanenko, A. M.; Suslin, S. V.; Vikhrev, V. V.

    2015-11-01

    Axial plasma jets at the final stage of plasma focus discharge filled by neon or argon were studied by the method of shearing interferometry. It was found that neon plasma is more stable than argon one and jets in neon are stronger than in argon. The velocity of current sheath, taken from experiment, is Vsh = (2-3) 106 cm/s, while the velocity of cumulative jet is Vj = (3-4) 107 cm/s. These features are supported by theoretical interpretation given in the frame of 2D MHD model.

  9. Flush-mounted probe diagnostics for argon glow discharge plasma

    SciTech Connect

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

    2014-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    In this paper, an atmospheric pressure plasma jet sustained in pure argon and an argon/water vapour mixture has been used to modify the surface of polypropylene (PP) films. The gas temperature of the plasma jet was found to be 625 K in an active zone between the electrodes and was found to increase in the afterglow. Based on these results, the PP films are placed as close as possible to the edge of the capillary in order to avoid thermal damage to the polymer. XPS results on the untreated and modified PP samples revealed incorporation of a significant amount of oxygen on the polymer surface, however, this oxygen inclusion is more pronounced for the argon/water vapour jet due to the higher radicals density in the jet afterglow. One can therefore conclude that adding water vapour to an argon plasma jet can be a convenient way to increase the efficiency of plasma surface modification.

  11. Nanopillar ITO electrodes via argon plasma etching

    SciTech Connect

    Van Dijken, Jaron G.; Brett, Michael J.

    2012-07-15

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

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

    NASA Astrophysics Data System (ADS)

    Girshick, Steven; Agarwal, Pulkit

    2012-10-01

    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.

  13. Low Temperature Atmospheric Argon Plasma: Diagnostics and Medical Applications

    NASA Astrophysics Data System (ADS)

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

    This study was devoted to diagnostic of low temperature plasma produced by microwave generator and investigation of its bactericidal effect against bacteria in biofilms and within eukaryotic cells. The profile of gas temperature near the torch outlet was measured. The spectrum in a wide range of wavelengths was derived by the method of optical emission spec-troscopy. Probe measurements of the floating potential of plasma were car-ried out. The estimation and adaptation of parameters of plasma flow (tem-perature, velocity, ion number density) according to medico-technical requirements were produced. The model of immersed surface-associated biofilms formed by Gram-negative bacteria, Pseudomonas aeruginosa and Burkholderia cenocepacia, and Gram-positive bacteria, Staphylococcus aureus, was used to assess bactericidal effects of plasma treatment. Reduction in the concentration of live bacteria in biofilms treated with plasma for 5 min was demonstrated by measuring Live/Dead fluorescent labeling and using direct plating. The intracellular infection model with the pathogenic bacterium, Chlamydia trachomatis, was used to study the efficacy of microwave argon plasma against intracellular parasites. A 2 min plasma treatment of mouse cells infected with C. trachomatis reduced infectious bacteria by a factor of 2106. Plasma treatment diminished the number of viable host cells by about 20%. When the samples were covered with MgF2 glass to obstruct active particles and UV alone was applied, the bactericidal effect was re-duced by 5104 fold compared to the whole plasma.

  14. CHARGING AND COAGULATION OF DUST IN PROTOPLANETARY PLASMA ENVIRONMENTS

    SciTech Connect

    Matthews, L. S.; Land, V.; Hyde, T. W.

    2012-01-01

    Combining a particle-particle, particle-cluster, and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in plasma environments relevant for protoplanetary disks have been investigated, including the effect of electron depletion in high dust density environments. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, and that cluster-cluster aggregation is significantly more effective than particle-cluster aggregation. Comparisons of the grain structure show that with increasing aggregate charge the compactness factor, {phi}{sub {sigma}}, decreases and has a narrower distribution, indicating a fluffier structure. Neutral aggregates are more compact, with larger {phi}{sub {sigma}}, and exhibit a larger variation in fluffiness. Overall, increased aggregate charge leads to larger, fluffier, and more massive aggregates.

  15. Plasma core reactor simulations using RF uranium seeded argon discharges

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1975-01-01

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

  16. Plasma core reactor simulations using RF uranium seeded argon discharges

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1976-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  18. Transition radiation energy loss in inductively coupled argon plasma

    NASA Astrophysics Data System (ADS)

    Ren, Yuping; Long, J. D.; Xu, S.

    2007-07-01

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

  19. Transport Properties of Equilibrium Argon Plasma in a Magnetic Field

    SciTech Connect

    Bruno, D.; Laricchiuta, A.; Chikhaoui, A.; Kustova, E. V.; Giordano, D.

    2005-05-16

    Electron electrical conductivity coefficients of equilibrium Argon plasma in a magnetic field are calculated up to the 12th Chapman-Enskog approximation at pressure of 1 atm and 0.1 atm for temperatures 500K-20000K; the magnetic Hall parameter spans from 0.01 to 100. The collision integrals used in the calculations are discussed. The convergence properties of the different approximations are assessed. The degree of anisotropy introduced by the presence of the magnetic field is evaluated. Differences with the isotropic case can be very substantial. The biggest effects are visible at high ionization degrees, i.e. high temperatures, and at strong magnetic fields.

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

    NASA Astrophysics Data System (ADS)

    Kaneko, T.; Takaya, H.; Hatakeyama, R.

    2006-12-01

    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 (Sin; n =1-17) but also Si cluster doped with Ar atom (ArSin; 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@Sin complexes. Furthermore, the mass spectrum of Ar@Sin indicates the existence of the magic numbered cluster size n =15, 16 similar to the metal encapsulated Si clusters.

  1. Simulation studies of plasma target compression by argon liners

    NASA Astrophysics Data System (ADS)

    Zhang, Lina; Kim, Hyoungkeun; Samulyak, Roman; Roman Samulyak Team

    2013-10-01

    Simulation studies of plasma liners, formed by the merger of argon plasma jets, and the compression of plasma targets in the concept of the plasma jet driven magnetoinertial fusion have been performed using FronTier code. FromTier is a hybrid Lagrangian-Eulerian code that uses explicit tracking of material interfaces, thus enabling accurate resolution of hydro instabilities, and average ionization EOS models for high-Z materials. The jets merger process is accomplished through a cascade of oblique shock waves leading to the non-uniformity of imploding plasma liner and causing the Reyleigh-Taylor instability of target during compression. The stagnation pressure, deconfinement time, Rayleigh-Taylor instabilities of the target surface, and the production of fusion neutrons were analyzed for 2D simulations that included 8, 16, and 32 jets, 3D simulation with 90 jets, and compared with the corresponding cylindrically (2D) and spherically (3D) symmetric simulations. The liner non-uniformity induces instabilities in the plasma targets that result in the reduction of stagnation pressure and fusion energy. For example, 8 time reduction of the stagnation pressure and 31 time reduction of the fusion energy was observed when the 2D simulation involving 16 jets was compared to 1D simulation.

  2. Effect of the levitating microparticle cloud on radiofrequency argon plasma

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Narushima, Kazuo; Okamoto, Nanami

    2013-10-01

    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.

  4. Electron Density Measurement of Argon Containing Plasmas by Saturation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nishiyama, S.; Wang, H.; Tomioka, S.; Sasaki, K.

    2014-10-01

    Langmuir probes are widely used for electron density measurements in plasmas. However, the use of a conventional probe should be avoided in a plasma which needs high purity because of the possibility of contamination. Optical measurements are suitable for these plasmas. In this work, we applied saturation spectroscopy to the electron density measurement. The peak height of the saturation spectrum is affected by the relaxation frequency of the related energy levels. In the case of the metastable levels of argon, the electron impact quenching rate, which is proportional to the electron density, is the dominant factor. In our experiments, an inductively coupled plasma source and a tunable cw diode laser were used. The frequency of the laser was scanned over the Doppler width of the 4 s[3/ 2 ] 2 o - 4 p[ 3 / 2 ] 2 (763.51 nm) transition. The experimental saturation spectrum was composed of a sharp Lorentzian peak and a broad base component, which was caused by velocity changing collisions. We deduced a new relationship between the saturation parameter and the measured saturated absorption spectrum with considering velocity changing collisions. We confirmed a linear relationship, which was expected theoretically, between the inverse of the saturation parameter and the electron density. Part of this work is supported by JSPS KAKENHI Grant Number 24540529.

  5. Nonthermal Argon Plasma Generator and Some Potential Applications

    NASA Astrophysics Data System (ADS)

    Bunoiu, M.; Jugunaru, I.; Bica, I.; Balasoiu, M.

    2015-12-01

    A laboratory - made nonthermal plasma generator is presented. It has a diameter of 0.020 m and length of 0.155 m and contains two electrodes. The first electrode is a 2% Th-W alloy, 0.002 m in diameter bar, centred inside the generator's body by means of a four channel teflon piece; the other three channels, 0.003 m in diameter, are used for Ar supply. The second electrode is a nozzle of 0.002 m - 0.008 m diameter and 0.005m length. A ~500 kV/m electric field is generated between the two electrodes by a high frequency source (13.56 MHz ±5%), equipped with a OT-1000 (Tungsram) power triode. For Ar flows ranging from 0.00008 m3/s to 0.00056 m3/s, a plasma jet of length not exceeding 0.015 m and temperature below 315 K is obtained. Anthurium andraeanumis sample , blood matrix, human hair and textile fibers may be introduced in the plasma jet. For time periods of 30 s and 60 s, various effects like, cell detexturization, fast blood coagulation or textile fiber or hair cleaning and smoothing are obtained. These effects are presented and discussed in the paper.

  6. Argon plasma modeling with detailed fine-structure cross sections

    SciTech Connect

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

    2012-03-01

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

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

    SciTech Connect

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

    2007-06-25

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  9. Interaction of an argon plasma jet with a silicon wafer

    NASA Astrophysics Data System (ADS)

    Engelhardt, Max; Pothiraja, Ramasamy; Kartaschew, Konstantin; Bibinov, Nikita; Havenith, Martina; Awakowicz, Peter

    2016-04-01

    A filamentary discharge is ignited in an argon plasma jet under atmospheric pressure conditions. The gas discharge is characterized with voltage-current measurements, optical emission spectroscopy and an ICCD-camera with a high temporal resolution down to 10 ns. In the effluent of the plasma jet, filaments come into contact with the surface of a silicon wafer and modify it, namely etching traces are produced and microcrystals are deposited. These traces are studied with optical and electron microscopes. The material of the deposited microcrystals and the surface modifications of the silicon wafer are analyzed with Raman microspectroscopy. Amorphous silicon is found within the etching traces. The largest part of the deposited microcrystals are composed of nitratine (NaNO3) and some of them are calcite (CaCO3). Analyzing the possible reasons for the silicon wafer modifications we come to the conclusion that plasmoids, which are produced near the substrate surface by interaction with ionization waves, are a plausible explanation for the observed surface modifications of the silicon wafer.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

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

    SciTech Connect

    Tu Xin; Yan Jianhua; Yu Liang; Cen, Kefa; Cheron, Bruno

    2007-09-24

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

  13. Radiating plasma species density distribution in EUV-induced plasma in argon: a spatiotemporal experimental study

    NASA Astrophysics Data System (ADS)

    van der Horst, R. M.; Beckers, J.; Osorio, E. A.; van de Ven, T. H. M.; Banine, V. Y.

    2015-12-01

    In this contribution we experimentally study temporally and spatially resolved radiating plasma species density distribution in plasma induced by irradiating a low pressure argon gas with high energy photons with a wavelength of 13.5 nm, i.e. extreme ultraviolet (EUV). This is done by recording the optical emission spatially and temporally resolved by an iCCD camera as a function of the argon gas pressure. Our experimental results show that the emission intensity, i.e. density of radiating plasma species, depends quadratically on the gas pressure. The linear term is due to photoionization and simultaneous excitation by EUV photons, the quadratic term due to electron impact excitation by electrons generated by photoionization. The decay of radiating plasma species can be divided into two phases. At time scales shorter than 10 μs (first phase), the decay is governed by radiative decay of radiating plasma species. At longer time scales (second phase, >10 μs), the decay is dominated by diffusion and subsequent de-excitation at the wall. The experimental decay and expansion during this phase corresponds well with a simplified diffusion model. In order to gain more insight in this exotic type of plasma, we compare the electron density from previous measurements with the results obtained here.

  14. Absorption Measurements of 4s State Number density for a Microwave Argon Plasma

    NASA Astrophysics Data System (ADS)

    Li, Yunlong; Gordon, Matthew; Roe, Larry; Hassouni, Khaled

    1999-10-01

    Optical emission and continuum measurements have been performed to characterize microwave argon plasmas. A Wavemat (model MPDR-3135) microwave diamond deposition system was used to generate the argon plasma at 5 Torr with an argon flow rate of 300 sccm. In a previous study, three excited states number densities (4p, 5p, and 5d) were obtained from the emission measurements. These data were used to validate our zero-dimensional (with diffusion) Collisional-Radiative Model (CRM) by matching these three excited state number densities with the prediction from the CRM. An energy balance study showed that the energy absorbed by the argon plasma was far less than the reading from the power meters, also in agreement with our CRM predictions. To better characterize the plasma, we have recently measured the 4s population through absorption at 7635. The light source was a low-pressure AC argon lamp. To calculate the 4s number density, the lineshapes of the argon lamp and the argon plasma are needed. The lineshape of the argon lamp was taken from previous work which used a similar lamp. However, the plasma lineshape depends on the electron number density, the number densities of related excited states, the electron and gas temperatures, etc. For our microwave plasma system, these parameters cannot be measured directly. Therefore, the plasma lineshape was calculated based on the parameters predicted from the CRM. The 4s state number density calculted from this lineshape matches the predicted one from the CRM within the experimental uncertainty, further validating our model.

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

    SciTech Connect

    Jauberteau, J. L.; Jauberteau, I.

    2012-11-15

    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.

  16. Reduction of analytical error in measurement of the concentration of coagulation factors in plasma.

    PubMed

    Uldall, A; Dybkr, R

    1972-01-01

    A modification of the method of Owren & Aas for the determination of relative arbitrary substance concentration of coagulation factors (II+VII+X) in plasma is presented. The coefficient of variation on repetends (today-yesterday) is reduced to 0.03 for results in the therapeutic as well as the 'normal' interval. An unusual composition of the plasma may be revealed. Thromboplastin-absorbed bovine plasma should be kept at -70 C. PMID:21488410

  17. Simulation of Plasma Characteristics for Inductively Coupled Argon Plasma Using Dual-Frequency Antennas

    NASA Astrophysics Data System (ADS)

    Li, Xue-Chun; Sun, Xiao-Yan; Wang, You-Nian

    2014-10-01

    A large-area wafer size is necessary for plasma processing in the micro-electronics industry. However, it is one of the most important issues to obtain uniform plasma over a large-area substrate in addition to high-density plasmas for the plasma processing. Recently, the experimental study on the dual-frequency inductively coupled plasma (ICP) has been reported as a mean of improving the plasma uniformity over the large-area substrate. In this work, we develop a self-consistent method combined with the electromagnetic theory and fluid model to simulate the plasma characteristics for dual-frequency inductively coupled argon plasma. In the model, the ICP source consists of two planar-spiral coils. We investigate the plasma uniformity problem by adjusting the parameters of the two coils, such as the RF current, the position of the coils and the RF frequency ratio. It was found that the uniformity of the ion density over the wafer is improved with dual-frequency antennas comparing with a single-frequency antenna. The plasma uniformity increases when the coils are located farther from the centre of the ICP source. It is consistent with the experimental study. This work was supported by the National Natural Science Foundation of China (No. 11175034, No. 11075029).

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

    SciTech Connect

    Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen; Uhm, Han S.

    2011-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    SciTech Connect

    Sharma, Rohit; Singh, Kuldip

    2014-03-15

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

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

    NASA Astrophysics Data System (ADS)

    Sharma, Rohit; Singh, Kuldip

    2014-03-01

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

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

    SciTech Connect

    Li Shouzhe; Xu Maochun; Zhang Xin; Zhang Jialiang

    2012-04-23

    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.

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

    PubMed

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

    2012-02-01

    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

  4. The response of the inductively coupled argon plasma to solvent plasma load: spatially resolved maps of electron density obtained from the intensity of one argon line

    NASA Astrophysics Data System (ADS)

    Weir, D. G. J.; Blades, M. W.

    1994-12-01

    A survey of spatially resolved electron number density ( ne) in the tail cone of the inductively coupled argon plasma (ICAP) is presented: all of the results of the survey have been radially inverted by numerical, asymmetric Abel inversion. The survey extends over the entire volume of the plasma beyond the exit of the ICAP torch; It extends over distances of z = 5-25 mm downstream from the induction coil, and over radial distances of ± 8 mm from the discharge axis. The survey also explores a range of inner argon flow rates ( QIN), solvent plasma load ( Qspl) and r.f. power: moreover, it explores loading by water, methanol and chloroform. Throughout the survey, ne was determined from the intensity of one, optically thin argon line, by a method which assumes that the atomic state distribution function (ASDF) for argon lies close to local thermal equilibrium (LTE). The validity of this assumption is reviewed. Also examined are the discrepancies between ne from this method and ne from Stark broadening measurements. With the error taken into account, the results of the survey reveal how time averaged values of ne in the ICAP respond over an extensive, previously unexplored range of experimental parameters. Moreover, the spatial information lends insight into how the thermal conditions and the transport of energy respond. Overall, the response may be described in terms of energy consumption along the axial channel and thermal pinch within the induction region. The predominating effect depends on the solvent plasma load, the solvent composition, the robustness of the discharge, and the distribution of solvent material over the argon stream.

  5. Characterization of an atmospheric double arc argon-nitrogen plasma source

    SciTech Connect

    Tu, X.; Cheron, B. G.; Yan, J. H.; Yu, L.; Cen, K. F.

    2008-05-15

    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.

  6. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect

    Chang, C.H.

    1992-08-01

    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.)

  7. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect

    Chang, C.H.

    1992-01-01

    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.)

  8. Introduction of argon beam coagulation functionality to robotic procedures using the ABC D-Flex probe: equivalency to an existing laparoscopic instrument

    NASA Astrophysics Data System (ADS)

    Merchel, Renée. A.; Barnes, Kelli S.; Taylor, Kenneth D.

    2015-03-01

    INTRODUCTION: The ABC® D-Flex Probe utilizes argon beam coagulation (ABC) technology to achieve hemostasis during minimally invasive surgery. A handle on the probe allows for integration with robotic surgical systems and introduces ABC to the robotic toolbox. To better understand the utility of D-Flex, this study compares the performance of the D-Flex probe to an existing ABC laparoscopic probe through ex vivo tissue analysis. METHODS: Comparisons were performed to determine the effect of four parameters: ABC device, tissue type, activation duration, and distance from tissue. Ten ABC D-Flex probes were used to create 30 burn samples for each comparison. Ex vivo bovine liver and porcine muscle were used as tissue models. The area and depth of each burn was measured using a light microscope. The resulting dimensional data was used to correlate tissue effect with each variable. RESULTS: D-Flex created burns which were smaller in surface area than the laparoscopic probe at all power levels. Additionally, D-Flex achieved thermal penetration levels equivalent to the laparoscopic probe. CONCLUSION: D-Flex implements a small 7F geometry which creates a more focused beam. When used with robotic precision, quick localized superficial hemostasis can be achieved with minimal collateral damage. Additionally, D-Flex achieved equivalent thermal penetration levels at lower power and argon flow-rate settings than the laparoscopic probe.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

    Zhang Zhili; Shneider, Mikhail N.

    2010-03-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

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

    PubMed

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

    2004-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Chatterjee, Kaushik

    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.

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

    NASA Astrophysics Data System (ADS)

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

    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.

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

    PubMed

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

    2013-06-01

    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

  16. Plasma lipids and coagulation in patients with arteriosclerotic dementia

    PubMed Central

    Andreoli, V. M.; Ferrari, S.; Sirtori, C. R.; Biasi, G.; Morandini, M.

    1974-01-01

    Plasma lipids and lipoproteins, glucose, uric acid, and haemocoagulative parameters were studied in a group of 22 elderly hospitalized patients with arteriosclerotic dementia, and compared with those of a control group of a similar age. No significant differences were found in lipids, lipoproteins, glucose, or uric acid but the fibrinogen level was significantly raised in the group with arteriosclerotic dementia. A comparison of the metabolic parameters of the dementia patients with those of a group of subjects with peripheral occlusive arteriosclerosis showed, on the other hand, that this latter group had significantly raised plasma triglycerides as well as a significantly higher incidence of the Fredrickson phenotypes of hyperlipoproteinaemia. These findings indicate that the common laboratory parameters used to evaluate arteriosclerosis are not adequate to point out any pathogenic mechanism for arteriosclerotic dementia, and research should therefore be focused in other directions.

  17. On the plasma chemistry of a cold atmospheric argon plasma jet with shielding gas device

    NASA Astrophysics Data System (ADS)

    Schmidt-Bleker, Ansgar; Winter, Jörn; Bösel, André; Reuter, Stephan; Weltmann, Klaus-Dieter

    2016-02-01

    A novel approach combining experimental and numerical methods for the study of reaction mechanisms in a cold atmospheric \\text{Ar} plasma jet is introduced. The jet is operated with a shielding gas device that produces a gas curtain of defined composition around the plasma plume. The shielding gas composition is varied from pure {{\\text{N}}2} to pure {{\\text{O}}2} . The density of metastable argon \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) in the plasma plume was quantified using laser atom absorption spectroscopy. The density of long-living reactive oxygen and nitrogen species (RONS), namely {{\\text{O}}3} , \\text{N}{{\\text{O}}2} , \\text{NO} , {{\\text{N}}2}\\text{O} , {{\\text{N}}2}{{\\text{O}}5} and {{\\text{H}}2}{{\\text{O}}2} , was quantified in the downstream region of the jet in a multipass cell using Fourier-transform infrared spectroscopy (FTIR). The jet produces a turbulent flow field and features guided streamers propagating at several \\text{km}~{{\\text{s}}-1} that follow the chaotic argon flow pattern, yielding a plasma plume with steep spatial gradients and a time dependence on the \\text{ns} scale while the downstream chemistry unfolds within several seconds. The fast and highly localized electron impact reactions in the guided streamer head and the slower gas phase reactions of neutrals occurring in the plasma plume and experimental apparatus are therefore represented in two separate kinetic models. The first electron impact reaction kinetics model is correlated to the LAAS measurements and shows that in the guided streamer head primary reactive oxygen and nitrogen species are dominantly generated from \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) . The second neutral species plug-flow model hence uses an \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) source term as sole energy input and yields good agreement with the RONS measured by FTIR spectroscopy.

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

    SciTech Connect

    Munoz, Jose; Yubero, Cristina; Calzada, Maria Dolores; Dimitrijevic, Milan S.

    2008-10-22

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

  19. Inductively coupled plasma discharge in flowing non-argon gas at atmospheric pressure for spectrochemical analysis

    SciTech Connect

    Meyer, G. A.; Barnes, R. M.

    1984-11-13

    Disclosed is a novel apparatus for the production of a sustained inductively coupled non-argon plasma discharge in flowing gas in a 13-25 mm (analytical size) containment tube at atmospheric pressure. The apparatus is developed for elemental analysis of injected aerosol or powdered samples, and particularly for air monitoring applications.

  20. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

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

    SciTech Connect

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

    2012-02-15

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

  4. Fumonisin mycotoxicosis in broilers: plasma proteins and coagulation modifications.

    PubMed

    Espada, Y; Ruiz de Gopegui, R; Cuadradas, C; Cabaes, F J

    1997-01-01

    The effects of fumonisin B1 (FB1) intoxication in chickens were evaluated in three experiments. Two-day-old broiler chicks were fed a diet containing 10 mg pure FB1/kg feed for 6 days; some chicks were necropsied at this time, and others were allowed to recover for 5 wk before necropsy. In two other experiments, 2-day-old chicks were fed a broiler starter ration prepared with Fusarium moniliforme culture material containing FB1; one group received 30 mg/kg for 2 wk, and another received 300 mg FB1/kg for 8 days. Compared with controls, intoxicated chicks exhibited decreased prothrombin time, increased plasma fibrinogen (not included for the group receiving 30 mg/kg of culture material), and increased antithrombin III activity. Simultaneously decreased serum albumin concentration and increased serum globulins could be observed in groups intoxicated with F. moniliforme culture material containing FB1. The group allowed to recover for 5 wk did not exhibit modifications in hemostasis or serum proteins compared with controls. The results indicate that low doses of pure FB1 (10 mg/kg) and FB1 from F. moniliforme culture material (30 mg/kg) may alter hemostasis and serum proteins in young chicks. PMID:9087322

  5. Evaluation of Some Plasma Coagulation Factors in Women with Spontaneous Miscarriage

    PubMed Central

    Besharat, Mahsa; Tabandeh, Afsane; Keshtkar, Abbasali; Mobasheri, Elham; Besharat, Sima; Joshaghani, Hamidreza

    2015-01-01

    Background It has been reported that 15-20% of parous female have experienced at least one miscarriage, while 3% of them have experienced two miscarriages. The goal of this study was to evaluate the plasma level of coagulation factors in women with a history of spontaneous abortions. Materials and Methods In this case-control study, 82 women with a history of two or more abortions referred to the six private gynecologic clinics in Gorgan city without any structural abnormality were recruited during 2011-2012. Plasma levels of antithrombin III (ATIII) using colorimetric assay, protein C, protein S, factor V Leiden and lupus anticoagulant (LAC) using coagulation method were measured. The control group was women with a history of normal delivery and no abortions. Those under anti-coagulant therapy were excluded from the study. Data were entered into the computer using the Statistical Package for the Social Sciences (SPSS, SPSS Inc., Chicago, IL, USA) version 16 and analyzed by Chi-square, t test and non-parametric tests. Results At least one abnormality was reported in 35 cases (42.7%). Among them, protein C deficiency was the most prevalent (30.5%). ATIII was abnormal in 17.1% and lupus anti-coagulant was abnormal in 8.5%. Factor V Leiden was normal in all cases and protein S deficiency was only seen in one case. Conclusion We suggest to perform these tests in regards to the thrombophilia in cases with spontaneous abortions in order to find an early cure for this treatable disorder. PMID:26644853

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

    SciTech Connect

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

    2007-09-15

    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.

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

    SciTech Connect

    Akatsuka, Hiroshi

    2009-04-15

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

  8. Electron Energy Distributions in Inductively Coupled Plasma of Argon

    NASA Astrophysics Data System (ADS)

    Yonemura, Shigeru; Nanbu, Kenichi

    2001-12-01

    The effects of gas pressure, electron density and coil current on the electron energy distribution functions (EEDFs) in inductively coupled discharges of argon are studied numerically. The EEDF for low gas pressure is close to the Maxwellian, whereas the EEDF for high gas pressure is lower than the Maxwellian in the high energy tail due to inelastic collisions. Since the energy loss due to inelastic collisions is compensated by the energy deposition due to the induced electric field, the EEDF near the quartz wall becomes close to the Maxwellian. However, this EEDF is not the real Maxwellian because the velocity distribution of electrons near the wall is anisotropic in velocity space and hence in nonequilibrium. We proposed the factor ? which represents the magnitude of the effect of Coulomb collisions. The factor is the ratio of electron-electron collision frequency to electron-atom inelastic collision frequency. The effect of Coulomb collisions on the EEDF is negligibly small for ? < 0.01. The distribution function for the azimuthal component of electron velocity varies significantly as the radial position changes, whereas the distribution functions for the other components do not vary so much.

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

  10. Experimental measurement of the total energy losses in a low pressure inductively coupled argon plasma

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    Total energy losses per electron-ion pair lost (?T) were measured experimentally in a low pressure inductively coupled argon plasma. A floating probe working at very low bias voltage (1 V) was used to obtain the electron temperatures and plasma densities at the plasma-sheath boundary. ?T was found from a power balance equation between the absorbed power and dissipated power by electrons and ions. At 10 mTorr, the measurement shows that the measured ?T (100 V) gradually decreased with absorbed power, and this indicates that the ionization efficiency enhances by multistep ionizations. These ?T are consistent with the theoretical results.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

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

    PubMed Central

    Davis, BJH; Bagenal, J; Cullen, S; Appleton, S

    2013-01-01

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

  13. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

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

    PubMed Central

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

    2010-01-01

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

  15. Experimental Investigation of Laser-sustained Plasma in Supersonic Argon Flow

    SciTech Connect

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

    2011-11-10

    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.

  16. Measurements of rat plasma coagulation proteins during prolonged exposure to diethylstilbesterol.

    PubMed

    Owens, M R; Cimino, C D; Donnelly, J

    1986-05-01

    The effects of diethylstilbesterol (DES) on concentration of selected plasma coagulation proteins in male rats was studied sequentially over a 28-day period. At the outset of the study, male rats underwent orchiectomy and implantation of a pellet containing DES 5.0 mg or a placebo pellet. At intervals of 7 days, 3 of the animals from each treatment group were sacrificed and blood samples were withdrawn for assay. Plasma concentrations of Factor II (prothrombin) and Factor VII, two vitamin K-dependent coagulation proteins, were significantly decreased in DES-treated animals (approximately 70% normal activity for both Factors) compared to placebo-treated animals. In contrast, Factor VIII activity was higher with DES treatment than with placebo. Plasma concentrations of both antithrombin III (AT III) and plasminogen were decreased in DES-treated animals compared to placebo by immunologic as well as activity assays. Albumin concentrations were not different between the two groups at any point of study, although both were increased at day 21 compared to beginning values. Fibronectin concentrations were slightly decreased in DES-treated animals compared to those which received placebo. The combination of orchiectomy and treatment with DES had profound metabolic effects on the animals; the DES treated animals had a mean body weight loss of 100 g after 28 days, while the placebo group gained an average of 78 g compared to a control group (no surgery) which had average weight gain of 85 g during the 28 day period of study. PMID:3715807

  17. Comparison between experiment and simulation for argon inductively coupled plasma

    SciTech Connect

    Gao Fei; Zhao Shuxia; Li Xiaosong; Wang Younian

    2009-11-15

    In order to include the nonlocal characteristics of electrons and investigate the inductively coupled plasma (ICP) resources more completely, we have developed a hybrid Monte Carlo (MC)/fluid hybrid model and calculated the axial and radial distributions of electron density, electron temperature, plasma potential, and electron energy distribution functions (EEDFs) of Ar discharge in a planar ICP. Furthermore, to make the model more practical, we still incorporate the effects of metastable atoms, whose sets of rate coefficients and density are, respectively, calculated through the electron MC part and fluid module. Besides, the corresponding Langmuir probe measurements are used to compare these data to validate the simulated results. Under all the selected discharge powers and pressures, the theoretically simulated and experimentally measured quantity profiles agree reasonably with each other, embodied in the generally identical magnitude ranges and spatial distributions. Furthermore, the interpretations about their detailed differences are given, which are based on the designs of both experimental schematic and model configuration. The analysis implements that the inclusions of electron-electron collision and a neutral density distribution into the hybrid model are likely to improve the comparison between the model predictions and experiment diagnostics. Furthermore, the evolution of plasma parameters and EEDFs with discharge conditions is discussed.

  18. Ion Transport in Chlorine/Argon ECR Plasma*

    NASA Astrophysics Data System (ADS)

    Lampe, M.; Joyce, G.; Fernsler, R. F.; Manheimer, W. M.; Slinker, S. P.

    1999-11-01

    We have used the quasineutral particle simulation code QUASI-rz (which includes Monte Carlo and Langevin representations of the relevant charged-neutral and charged-charged collision processes) to study transport and distributions of various species in an axisymmetric ECR reactor, operating with pressures on the order of a few mTorr and plasma density up to the order of 10^12 cm-3. In this high-density electronegative plasma, ion-ion Coulomb collisions play an important role, since positive and negative ions are driven in opposite directions by the potential gradients, but are strongly coupled by collisions. The velocity distributions of both negative and positive ions are significantly isotropized as a result of ion-ion collisions, and negative ions also contribute to the heating of all heavy species. The kinetics of the plasma is spatially varying and is controlled by the interplay of species transport and a number of processes, including dissociative recombination of Cl_2^+ ions, recombination and collisional detachment of Cl^ ions, and wall recombination of atomic Cl. Densities and distribution functions of various species will be shown, at different locations in the reactor and for operating times up to 500 msec. *Work sponsored by the Office of Naval Research

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

    NASA Astrophysics Data System (ADS)

    Mahmood, Ghoranneviss; Sheila, Shahidi; Jakub, Wiener

    2010-04-01

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

  20. Risk assessment of a cold argon plasma jet in respect to its mutagenicity.

    PubMed

    Wende, K; Bekeschus, S; Schmidt, A; Jatsch, L; Hasse, S; Weltmann, K D; Masur, K; von Woedtke, T

    2016-03-01

    Cold atmospheric pressure plasmas represent a favorable option for the treatment of heat sensitive materials and human or animal tissue. Beneficial effects have been documented in a variety of medical conditions, e.g., in the treatment of chronic wounds. It is assumed that the main mechanism of the plasma's efficacy is mediated by a stimulating dissipation of energy via radiation and/or chemical energy. Although no evidence on undesired side effects of a plasma treatment has yet been presented, skepticism toward the safety of the exposure to plasma is present. However, only little data regarding the mutagenic potential of this new treatment option is available. Accordingly, we investigated the mutagenic potential of an argon plasma jet (kinpen) using different testing systems in accordance with ISO norms and multiple cell lines: a HPRT1 mutation assay, a micronucleus formation assay, and a colony formation assay. Moderate plasma treatment up to 180s did not increase genotoxicity in any assay or cell type investigated. We conclude that treatment with the argon plasma jet kinpen did not display a mutagenic potential under the test conditions applied and may from this perspective be regarded as safe for the use in biomedical applications. PMID:26994493

  1. Diagnostics of surface wave driven low pressure plasmas based on indium monoiodide-argon system

    NASA Astrophysics Data System (ADS)

    gn, C. M.; Kaiser, C.; Kling, R.; Heering, W.

    2015-06-01

    Indium monoiodide is proposed as a suitable alternative to hazardous mercury, i.e. the emitting component inside the compact fluorescent lamps (CFL), with comparable luminous efficacy. Indium monoiodide-argon low pressure lamps are electrodelessly driven with surface waves, which are launched and coupled into the lamp by the surfatron, a microwave coupler optimized for an efficient operation at a frequency of 2.45 GHz. A non intrusive diagnostic method based on spatially resolved optical emission spectroscopy is employed to characterize the plasma parameters. The line emission coefficients of the plasma are derived by means of Abels inversion from the measured spectral radiance data. The characteristic plasma parameters, e.g. electron temperature and density are determined by comparing the experimentally obtained line emission coefficients with simulated ones from a collisional-radiative model. Additionally, a method to determine the absolute plasma efficiency via irradiance measurements without any goniometric setup is presented. In this way, the relationship between the plasma efficiency and the plasma parameters can be investigated systematically for different operating configurations, e.g. electrical input power, buffer gas pressure and cold spot temperature. The performance of indium monoiodide-argon plasma is compared with that of conventional CFLs.

  2. [Influence of Argon Content on Plasma Temperature of Single Filament in Dielectric Barrier Discharge].

    PubMed

    Fu, Hong-yan; Dong, Li-fang; Zhao, Yang

    2015-03-01

    The single filament (also referred to as monofilament) which composed of two parts including the center spot and the outer halo is observed and researched for the first time in dielectric barrier discharge, which filled with gas-mixture of argon and air. The pictures taken from the experiment show that the diameter of the monofilament decreases with the increasing of the content of the argon in the argon-air mixture, and at the same time there is an obvious difference on brightness between the center spot and the outer halo. All of these phenomenons suggest that the center spot and the outer halo are probably in different plasma state. The micro character of the center spot and the outer halo is researched seriously in the experiment by the time-resolved measurement with optical method. Three plasma temperatures of the center spot and the outer halo in single filament in different argon content are studied in details by using optical emission spectra. The emission spectra of the N2 second positive band (C3 π(u) --> B3 πg) are measured, from which the molecule vibrational temperature of the center spot and the outer halo are calculated. Based on the relative intensity of the N2 line at 391.4 nm and the N2 line at 394. 1 nm, the changing relationship of the average electron energy of the center spot and the outer halo with argon content is investigated. The spectral lines of Ar I 763.2 nm (2P6 --> 1S5) and 772.077 nm (2P2 --> 1S3) are chosen to estimate electron excitation temperature of the center spot and the outer halo by the relative intensity ratio method. The results show that the optical signal corresponding to the first lasge pulse is the center spot, whose signal intensity is a litter weaker; and the optical signal containing the whole pulse is the outer halo, whose signal intensity is stronger. The three plasma temperatures including the molecule vibrational temperature, average electron energy and electron excitation temperature of the outer halo are higher than those of the spot at the same argon content without exception. In addition, the molecule vibrational temperature of the center spot and the outer halo decrease with the argon content increases from 30% to 50%, while on the other hand, electron excitation temperature and average electron energy are decrease gradually. PMID:26117860

  3. Formation mechanism of graphite hexagonal pyramids by argon plasma etching of graphite substrates

    NASA Astrophysics Data System (ADS)

    Glad, X.; de Poucques, L.; Bougdira, J.

    2015-12-01

    A new graphite crystal morphology has been recently reported, namely the graphite hexagonal pyramids (GHPs). They are hexagonally-shaped crystals with diameters ranging from 50 to 800 nm and a constant apex angle of 40°. These nanostructures are formed from graphite substrates (flexible graphite and highly ordered pyrolytic graphite) in low pressure helicon coupling radiofrequency argon plasma at 25 eV ion energy and, purportedly, due to a physical etching process. In this paper, the occurrence of peculiar crystals is shown, presenting two hexagonal orientations obtained on both types of samples, which confirms such a formation mechanism. Moreover, by applying a pretreatment step with different time durations of inductive coupling radiofrequency argon plasma, for which the incident ion energy decreases at 12 eV, uniform coverage of the surface can be achieved with an influence on the density and size of the GHPs.

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    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.

  5. Numerical Simulation of an Optically Pumped CO/Argon Plasma

    NASA Astrophysics Data System (ADS)

    Dietz, Doug; Subramaniam, Vish V.; Aithal, Shashi M.

    2001-10-01

    Volumetrically diffuse plasmas can be produced in some gas mixtures by optical pumping. Low-lying vibrational modes (v<10) of CO can be excited by resonance absorption of CO laser radiation. Population of very high vibrational levels occurs by vibration-vibration exchange collisions, leading to a highly non-Boltzmann distribution in the vibrational populations. Ionization in these types of plasmas occurs by an associative mechanism in collisions between two highly vibrationally excited molecules. We present 2-D axi-symmetric modeling calculations of an optically pumped, flowing CO/Ar gas mixture, with the aim of predicting steady-state spatial distributions of electron densities. The multi-dimensional model accounts for state-specific vibration-vibration and vibration-translation energy transfer processes as well as associative ionization processes, and examines the variation of electron density in such an electrodeless discharge. In addition to the gas phase Boudouard reaction (CO(v)+CO(w)arrowC+CO_2) and vibration to electronic transfer from the ground electronic state (X^1?) to an excited state (A^1?) are included in the model. Coupling of the flow with vibrational kinetics and associative ionization processes is examined.

  6. Langmuir Probe Diagnostics of Low-pressure Inductively Coupled Argon Plasmas in a Magnetic Field

    NASA Astrophysics Data System (ADS)

    Meshcheryakova, E.; Zibrov, M.; Kaziev, A.; Khodachenko, G.; Pisarev, A.

    Plasma parameters of an inductively coupled radio frequency discharge in argon in an external axial magnetic field have been investigated at working pressures of 510-4-110-2 mbar and magnetic field of 0-80 G. Axial distributions of plasma density and electron temperature have been derived from Langmuir probe measurements. Plasma density monotonically increased with the increase in magnetic field at the highest pressure (110-2 mbar), whereas at lower pressures it reached its maximum (? 31011 cm-3) at a B-field ? 19 G. Plasma density was almost independent of the working pressure under low pressure regimes, which means that the degree of plasma ionization increased with the decrease in pressure reaching several percent at 510-4 mbar.

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

    PubMed

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

    1995-07-01

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

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

    PubMed

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

    2009-07-01

    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

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

    SciTech Connect

    Li, S.-Z.; Lim, J.-P.; Kang, Jung G.; Uhm, Han S.

    2006-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  11. VUV Emission of Microwave Driven Argon Plasma Source

    NASA Astrophysics Data System (ADS)

    Henriques, Julio; Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Dias, Francisco; Ferreira, Carlos

    2013-09-01

    An experimental and kinetic modeling investigation of a low-pressure (0.1-1.2 mbar), surface wave (2.45 GHz) induced Ar plasma as a source vacuum ultraviolet (VUV) light is presented, using visible and VUV optical spectroscopy. The electron density and the relative VUV emission intensities of excited Ar atoms (at 104.8 nm and 106.6 nm) and ions (at 92.0 nm and 93.2 nm) were determined as a function of the microwave power and pressure. The experimental results were analyzed using a 2D self-consistent theoretical model based on a set of coupled equations including the electron Boltzmann equation, the rate balance equations for the most important electronic excited species and for charged particles, the gas thermal balance equation, and the wave electrodynamics. The principal collisional and radiative processes for neutral Ar(3p54s) and Ar(3p54p) and ionized Ar(3s3p6 2S1/2) levels are accounted for. Model predictions are in good agreement with the experimental measurements. This study was funded by the Foundation for Science and Technology, Portuguese Ministry of Education and Science, under the research contract PTDC/FIS/108411/2008.

  12. Investigating the effect of Argon Pressure on DC and High Power Magnetron Plasmas

    NASA Astrophysics Data System (ADS)

    Bernales, Baysha; Bolat, Rustem; Anders, Andre; Slack, Jonathan; PAG Team; EETD Team

    2013-10-01

    Smart Glass is fabricated by depositing thin films of specialized material onto a transparent substrate. When a potential is applied across the surface of the Smart Glass, it changes its optical properties. Direct Current Magnetron Sputtering (DCMS) and High Power Impulse Magnetron Sputtering (HiPIMS) are two methods of PVD that are used to fabricate this material. In previous research, it has been noted that magnetron plasmas have localized ionization zones that rotate clockwise in DCMS and counterclockwise in HiPIMS. Not much is known about what causes the change in rotation. This research seeks to investigate what occurs during the first moments of plasma evolution. Both DC and high power magnetron plasmas were observed as Argon pressure was varied. It was found that pressure had a very pronounced effect on the floating-point potential signal that was received from the probes placed in the plasma. It was found that when a high-pressure jet of Argon was injected into the system, that the rotation pattern of the DC magnetron plasma was disrupted. It was also found that at certain pressures, the voltage signal was less indicative of azimuthal rotation and more indicative of z-direction breathing modes.

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

    SciTech Connect

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

    2012-05-01

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

  14. First steps towards the reaction kinetics of HMDSO in an atmospheric pressure plasma jet in argon

    NASA Astrophysics Data System (ADS)

    Loffhagen, Detlef; Becker, Markus M.; Foest, Rüdiger; Schäfer, Jan; Sigeneger, Florian

    2014-10-01

    Hexamethyldisiloxane (HMDSO) is a silicon-organic compound which is often used as precursor for thin-film deposition by means of plasma polymerization because of its high deposition rate and low toxicity. To improve the physical understanding of the deposition processes, fundamental investigations have been performed to clarify the plasma-chemical reaction pathways of HMDSO and their effect on the composition and structure of the deposited film. The current contribution represents the main primary and secondary plasma-chemical processes and their reaction products in the effluent region of an argon plasma jet at atmospheric pressure. The importance of the different collision processes of electrons and heavy particles are discussed. Results of numerical modelling of the plasma jet and the Ar-HMDSO reaction kinetics indicate that the fragmentation of HMDSO is mainly initiated by collisions with molecular argon ions, while Penning ionization processes play a minor role for the reaction kinetics in the effluent region of the jet. The work has been supported by the German Research Foundation (DFG) under Grant LO 623/3-1.

  15. Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics

    SciTech Connect

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

    2013-04-15

    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.

  16. Stability and excitation dynamics of an argon micro-scaled atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Dünnbier, M.; Becker, M. M.; Iseni, S.; Bansemer, R.; Loffhagen, D.; Reuter, S.; Weltmann, K.-D.

    2015-12-01

    A megahertz-driven plasma jet at atmospheric pressure—the so-called micro-scaled atmospheric pressure plasma jet (μAPPJ)—operating in pure argon has been investigated experimentally and by numerical modelling. To ignite the discharge in argon within the jet geometry, a self-made plasma tuning unit was designed, which additionally enables measurements of the dissipated power in the plasma itself. Discharges in the α-mode up to their transition to the γ-mode were studied experimentally for varying frequencies. It was found that the voltage at the α–γ transition behaves inversely proportional to the applied frequency f and that the corresponding power scales with an f   3/2law. Both these findings agree well with the results of time-dependent, spatially one-dimensional fluid modelling of the discharge behaviour, where the f  3/2 scaling of the α–γ transition power is additionally verified by the established concept of a critical plasma density for sheath breakdown. Furthermore, phase resolved spectroscopy of the optical emission at 750.39 nm as well as at 810.37 nm and 811.53 nm was applied to analyse the excitation dynamics of the discharge at 27 MHz for different applied powers. The increase of the power leads to an additional maximum in the excitation structure of the 750.39 nm line emission at the α–γ transition point, whereas the emission structure around 811 nm does not change qualitatively. According to the fluid modelling results, this differing behaviour originates from the different population mechanisms of the corresponding energy levels of argon.

  17. A new air-cooled argon/helium-compatible inductively coupled plasma torch.

    PubMed

    Miyahara, Hidekazu; Iwai, Takahiro; Kaburaki, Yuki; Kozuma, Tomokazu; Shigeta, Kaori; Okino, Akitoshi

    2014-01-01

    A new inductively coupled plasma (ICP) torch with an air-cooling system has been designed and developed for both argon and helium plasma. The same torch and impedance-matching network could be used to generate stable Ar- and He-ICP. The torch consists of three concentric quartz tubes. The carrier gas, plasma gas, and cooling gas flow through the intervals between each tube. In an experiment, it was found that Ar-ICP could form a stable plasma under the following conditions: RF power of 1 kW, plasma gas flow rate of 11 L min(-1), and cooling gas flow rate of 20 L min(-1). For He-ICP, an input RF power of 2 kW, which is two-times higher than that of a conventional He-ICP, could be constantly applied to the plasma with plasma gas and cooling gas flow rates of 15 and 20 L min(-1), respectively. Using this torch, it is possible to realize lower plasma gas consumption for Ar- and He-ICP and a high-power drive for He-ICP. It has been found that the air-cooling gas stabilizes the shape of the plasma due to the pressure difference between the cooling gas and the plasma gas. PMID:24521909

  18. Normal and abnormal evolution of argon metastable density in high-density plasmas

    SciTech Connect

    Seo, B. H.; Kim, J. H.; You, S. J.

    2015-05-15

    A controversial problem on the evolution of Ar metastable density as a function of electron density (increasing trend versus decreasing trend) was resolved by discovering the anomalous evolution of the argon metastable density with increasing electron density (discharge power), including both trends of the metastable density [Daltrini et al., Appl. Phys. Lett. 92, 061504 (2008)]. Later, by virtue of an adequate physical explanation based on a simple global model, both evolutions of the metastable density were comprehensively understood as part of the abnormal evolution occurring at low- and high-density regimes, respectively, and thus the physics behind the metastable evolution has seemed to be clearly disclosed. In this study, however, a remarkable result for the metastable density behavior with increasing electron density was observed: even in the same electron density regime, there are both normal and abnormal evolutions of metastable-state density with electron density depending on the measurement position: The metastable density increases with increasing electron density at a position far from the inductively coupled plasma antenna but decreases at a position close to the antenna. The effect of electron temperature, which is spatially nonuniform in the plasma, on the electron population and depopulation processes of Argon metastable atoms with increasing electron density is a clue to understanding the results. The calculated results of the global model, including multistep ionization for the argon metastable state and measured electron temperature, are in a good agreement with the experimental results.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  20. Experimental measurements of the total energy loss in low pressure inductively coupled argon plasma

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    Total energy lost per electron-ion pair lost (?T) was measured experimentally in a low pressure inductively coupled argon plasma. ?T represents not only the elastic and inelastic collision energy loss of electron-neutral but also the kinetic energy loss when the electron and ion escape to the wall. In order to determine ?T, the modified power balance of a global model (spatially-averaged) is properly derived using some assumptions. A floating-type probe working at very low bias voltage (1.0 V) was applied to obtain the electron temperature and plasma density at the plasma-sheath boundary. At 10 mTorr, the measurement shows that the measured ?T100 V gradually decreased with absorbed power and began to saturate. These ?T are consistent with the theoretical results by Lee et al [1]. [1] Min-Hyong Lee, Sung-Ho Jang and Chin-Wook Chung, Phys. Plasmas, 13, 053502 (2006)

  1. Effect of the electron energy distribution on total energy loss with argon in inductively coupled plasmas

    SciTech Connect

    Kim, June Young; Kim, Young-Cheol; Kim, Yu-Sin; Chung, Chin-Wook

    2015-01-15

    The total energy lost per electron-ion pair lost ε{sub T} is investigated with the electron energy distribution function (EEDF). The EEDFs are measured at various argon powers in RF inductively coupled plasma, and the EEDFs show a depleted distribution (a discontinuity occurring at the minimum argon excitation threshold energy level) with the bulk temperature and the tail temperature. The total energy loss per electron-ion pair lost ε{sub T} is calculated from a power balance model with the Maxwellian EEDFs and the depleted EEDFs and then compared with the measured ε{sub T} from the floating probe. It is concluded that the small population of the depleted high energy electrons dramatically increases the collisional energy loss, and the calculated ε{sub T} from the depleted EEDFs has a value that is similar to the measured ε{sub T}.

  2. Modelling of indium(I) iodide-argon low pressure plasma

    NASA Astrophysics Data System (ADS)

    Ögün, C. M.; Truong, W.; Kaiser, C.; Kling, R.; Heering, W.

    2014-07-01

    A new collisional-radiative model for a mercury-free low pressure plasma based on an indium(I) iodide-argon system is presented. The electron impact cross sections and rate coefficients for ionization, excitation and dissociation, as well as de-excitation, three-body recombination and dissociative recombination, of studied fillings have been calculated. Additionally, the coefficients for free and ambipolar diffusion were determined. The rate balance equations for individual generation and loss processes have been created. Densities of ions, electrons and neutral particles (ground or metastable state) are presented as a function of electron temperature for varied lamp parameters, such as argon buffer gas pressure and cold spot temperature (coldest point of discharge vessel). With the help of the presented model, the line emission coefficients of essential emission lines of indium for given electron temperatures and densities can be predicted.

  3. Effect of the electron energy distribution on total energy loss with argon in inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Kim, June Young; Kim, Young-Cheol; Kim, Yu-Sin; Chung, Chin-Wook

    2015-01-01

    The total energy lost per electron-ion pair lost ?T is investigated with the electron energy distribution function (EEDF). The EEDFs are measured at various argon powers in RF inductively coupled plasma, and the EEDFs show a depleted distribution (a discontinuity occurring at the minimum argon excitation threshold energy level) with the bulk temperature and the tail temperature. The total energy loss per electron-ion pair lost ?T is calculated from a power balance model with the Maxwellian EEDFs and the depleted EEDFs and then compared with the measured ?T from the floating probe. It is concluded that the small population of the depleted high energy electrons dramatically increases the collisional energy loss, and the calculated ?T from the depleted EEDFs has a value that is similar to the measured ?T.

  4. Effects of argon gas pressure on its metastable-state density in high-density plasmas

    SciTech Connect

    Seo, B. H.; Kim, J. H.; You, S. J.

    2015-05-15

    The effect of argon gas pressure on its metastable density in inductively coupled plasmas (ICPs) is investigated by using the laser-induced fluorescence method. Our results show that the metastable-state density of argon varies with the gas pressure depending on the measurement position; the density decreases with the pressure at a position far from the ICP antenna, whereas it increases with the pressure at a position near the antenna. This contrast in the metastable-state density trend with the pressure is explained by considering the electron temperature variations at the two measurement positions. The theoretical interpretation and calculation using a global model are also addressed in detail in this paper.

  5. Reduction of a collisional-radiative mechanism for argon plasma based on principal component analysis

    SciTech Connect

    Bellemans, A.; Munafò, A.; Magin, T. E.; Degrez, G.; Parente, A.

    2015-06-15

    This article considers the development of reduced chemistry models for argon plasmas using Principal Component Analysis (PCA) based methods. Starting from an electronic specific Collisional-Radiative model, a reduction of the variable set (i.e., mass fractions and temperatures) is proposed by projecting the full set on a reduced basis made up of its principal components. Thus, the flow governing equations are only solved for the principal components. The proposed approach originates from the combustion community, where Manifold Generated Principal Component Analysis (MG-PCA) has been developed as a successful reduction technique. Applications consider ionizing shock waves in argon. The results obtained show that the use of the MG-PCA technique enables for a substantial reduction of the computational time.

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

    SciTech Connect

    Scharwitz, Christian; Makabe, Toshiaki

    2009-12-01

    One of the general challenges for the evaluation and interpretation of optical emission spectroscopy measurements is the occurrence of radiation trapping, which is also named self-absorption or opacity. A convenient technique to treat radiation trapping is the introduction of a parameter, which is called escape factor and gives a measure for the amount of radiation trapping. In this paper evaluations on the concept of escape factors are presented for an inductively coupled plasma in argon. Especially, the strong argon line at 811.53 nm, which arises from the transition of 2p{sub 9}-1s{sub 5}, is under consideration. To estimate escape factors for this line, a particular method is proposed and presented here. First experimental results are obtained under the restrictive assumptions that transitions into the resonant levels 1s{sub 2} and 1s{sub 4} are sufficiently optically thin and ratios of population densities are constant.

  7. Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

    NASA Astrophysics Data System (ADS)

    de Vries, N.; Palomares, J. M.; Iordanova, E. I.; van Veldhuizen, E. M.; van der Mullen, J. J. A. M.

    2008-10-01

    The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, ne, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, Te, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the ne values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 0.5) 1019 m-3, whereas the ne value (2 0.5) 1019 m-3 obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high (~1020 m-3). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the Te values obtained with TS are equal to 13 400 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

  8. Effect of Argon Plasma Treatment Variables on Wettability and Antibacterial Properties of Polyester Fabrics

    NASA Astrophysics Data System (ADS)

    Senthilkumar, Pandurangan; Karthik, Thangavelu

    2015-10-01

    In this research work, the effect of argon plasma treatment variables on the comfort and antibacterial properties of polyester fabric has been investigated. The SEM micrographs and FTIR analysis confirms the modification of fabric surface. The Box-Behnken design was used for the optimization of plasma process variables and to evaluate the effects and interactions of the process variables, i.e. operating power, treatment time and distance between the electrodes on the characteristics of polyester fabrics. The optimum conditions of operating power 600 W, treatment time 30 s, and the distance between the electrodes of 2.8 mm was arrived using numerical prediction tool in Design-Expert software. The plasma treated polyester fabrics showed better fabric characteristics particularly in terms of water vapour permeability, wickability and antibacterial activity compared to untreated fabrics, which confirms that the modified structure of polyester fabric.

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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+/-0.41017 cm-3, using 6.0 vol % O2 in argon at 150 W/cm3. The ozone concentration determined at the same conditions was 4.3+/-0.51014 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.

  10. Functionalization of carbon nanotubes by argon plasma-assisted ultraviolet grafting

    SciTech Connect

    Yan, Y.H.; Chan-Park, M.B.; Zhou, Q.; Li, C.M.; Yue, C.Y.

    2005-11-21

    We have demonstrated the functionalization of single-wall carbon nanotubes (SWNTs) by argon (Ar) plasma-assisted ultraviolet (UV) grafting of 1-vinylimidazole (VZ). The Ar plasma treatment generates defect sites at the tube ends and sidewalls, which act as the active sites for the subsequent UV grafting of VZ monomer. Atomic force microscopy analyses indicate that the original nanotube bundles exfoliate to individual tubes after the VZ grafting. By control of the deposited energy of Ar plasma treatment (200 W) and treatment time (5 min), no visible chopping of the functionalized SWNT was observed. This method may be extended to other vinyl monomers and offers another diverse way of sidewall functionalization of SWNT.

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

    SciTech Connect

    Lukina, N. A.; Sergeichev, K. F.

    2008-06-15

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

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

    SciTech Connect

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2008-03-19

    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.

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

    SciTech Connect

    Adam B. Sefkow and Samuel A. Cohen

    2009-04-09

    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 λD,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.

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

    SciTech Connect

    Boffard, John B. Lin, Chun C.; Culver, Cody; Wang, Shicong; Wendt, Amy E.; Radovanov, Svetlana; Persing, Harold

    2014-03-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    NASA Technical Reports Server (NTRS)

    Cambier, Jean-Luc

    1991-01-01

    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.

  18. Study on hairpin-shaped argon plasma jets resonantly excited by microwave pulses at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoquan; Xia, Guangqing; Zou, Changlin; Li, Ping; Hu, Yelin; Ye, Qiubo; Eliseev, S.; Stepanova, O.; Saifutdinov, A. I.; Kudryavtsev, A. A.; Liu, Minghai

    2015-07-01

    In the present study, atmospheric pressure argon plasma jets driven by lower-power pulsed microwaves have been proposed with a type of hairpin resonator. The plasma jet plume demonstrates distinctive characteristics, like arched plasma pattern and local plasma bullets. In order to understand how the hairpin resonator works, electromagnetic simulation of the electric field distribution and self-consistent fluid simulation of the interaction between the enhanced electric field and the pulse plasma plume are studied. Simulated spatio-temporal distributions of the electric field, the electron temperature, the electron density, and the absorbed power density have been sampled, respectively. The experimental and simulated results together suggest that the driving mechanism of the hairpin resonator works in the multiple electromagnetic modes of transmission line and microwave resonator, while the local plasma bullets are resonantly generated by local enhanced electric field of surface plasmon polaritons. Moreover, it should be noticed that the radian of the arched plasma plume is mainly affected by the input power and gas flow rate, respectively.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  20. High Speed Argon PlasmaJet Merging Studies in Support of PLX

    NASA Astrophysics Data System (ADS)

    Case, Andrew; Messer, Sarah; Brockington, Samuel; Wu, Linchun; Witherspoon, F. Douglas; Elton, Raymond

    2014-10-01

    Formation of an imploding plasma liner such as 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, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of temperature, velocity, and magnetic field. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code. Work supported by the US DOE OFES under Grants DE-FG02-05ER54810 and DE-FG02-08ER85114.

  1. Photoionized argon plasmas induced with intense soft x-ray and extreme ultraviolet pulses

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Wachulak, P.; Fok, T.; Węgrzyński, Ł.; Fiedorowicz, H.; Skrzeczanowski, W.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Dudzak, R.; Dostal, J.; Krousky, E.; Skala, J.; Ullschmied, J.; Hrebicek, J.; Medrik, T.

    2016-01-01

    In this work, photoionized plasmas were created by irradiation of gaseous argon with soft x-ray (SXR) and extreme ultraviolet (EUV) intense radiation pulses. Two different laser-produced plasma sources, employing a low energy Nd:YAG laser and a high energy iodine laser system (PALS), were used for creation of photoionized plasmas. In both cases the EUV or SXR beam irradiated the Ar stream, injected into a vacuum chamber synchronously with the radiation pulse. Emission spectra, measured for the Ar photoionized plasmas indicated strong differences in ionization degree for plasmas produced using low and high energy systems. In case of the the EUV driving pulses, emission lines corresponding to neutral atoms and singly charged ions were observed. In case of the SXR pulses utilized for the photoionized plasma creation, only Ar V–VIII emission lines were recorded. Additionally, electron density measurements were performed by laser interferometry employing a femtosecond laser system synchronized with the irradiating system. Maximum electron density for the Ar photoionized plasma, induced using the high energy system, reached 1.9 · 1018 cm‑3. Interferometric measurements performed for the moment of maximum intensity of the main laser pulse (t  =  0) revealed no fringe shift. Detection limit for the interferometric measurements was estimated. It allowed to estimate the upper limit for electron density at t  =  0 as 5 · 1016 cm‑3.

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

    SciTech Connect

    Sharma, Rohit; Singh, Kuldip; Singh, Gurpreet

    2011-08-15

    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}.

  3. Effect of Cryogenic Cooling for Gallium Nitride Film Placed in Argon Plasma

    NASA Astrophysics Data System (ADS)

    Ogawa, Daisuke; Nakano, Yoshitaka; Nakamura, Keiji

    2014-10-01

    There is no doubt for a gallium nitride (GaN) film to have plasma-induced damage (PID) when exposed in a plasma discharge. Our technique to make in-situ monitoring on a GaN film exposed in argon plasma is valuable toward to reveal the evolution of the damage. We evaluated the PID with photoluminescence (PL) that is excited with a ultra-violet light source. Our preliminary result showed that the PL intensity at the blue luminescence band (BL: 400--480 nm) increased while the intensity at yellow luminescence (YL: 480--700 nm) decreased as the plasma exposure time increased. Chen et al. previously found that PL spectrum changes due to both PID and substrate temperature. However, BL intensity is independent from the substrate temperature, while BL intensity is dependent on the degree of PID. In this experiment, we performed the plasma exposure to a GaN film under the situation when the substrate temperature was cooled with liquid nitrogen. The substrate temperature is set at -110 degC and exposed plasma in 15 minutes. In this condition, our BL stayed almost constant. This is an indication that we might be able to avoid the damage in the wavelength shorter than 480 nm. We will show more details from this results and further progresses in this presentation.

  4. Two discharge modes in an atmospheric pressure plasma jet array in argon

    NASA Astrophysics Data System (ADS)

    Fang, Zhi; Ruan, Chen; Shao, Tao; Zhang, Cheng

    2016-02-01

    In this paper, the generation and discharge modes of 2D atmospheric pressure plasma jet arrays in economic argon feeding gas with a honeycomb configuration is first reported. Two coupling and collimated discharge modes are achieved with the same array structure. The discharge modes are shown to depend on the gas flow rate and center-to-center distances of jets in the array. Stronger plasmas with higher plasma density than single jet can be obtained in coupling mode array at close proximity of jets in the array and small gas flow rate, while plasmas with moderate plasma density and relative large area can be obtained in the collimated mode array at far proximity of jets in the array. The power density and emission spectra from the centered plasma jet for the coupling mode array are both larger than those of the collimated mode. The appearance of the two discharge modes may be due to the hydrodynamic interactions between the seven individual Ar channels emerging from individual tubes with the air surrounding them.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    SciTech Connect

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

    2015-02-15

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

  7. Characteristics of a long and stable filamentary argon plasma jet generated in ambient atmosphere

    NASA Astrophysics Data System (ADS)

    Teodorescu, M.; Bazavan, M.; Ionita, E. R.; Dinescu, G.

    2015-04-01

    We present a study of a long (up to 60?mm) and thin (600??m) plasma jet generated at 13.56?MHz in argon expanding in an open atmosphere from inside of a thin glass tube. The discharge is operated with one annular external electrode on the tube, in the absence of any grounded electrode in the discharge proximity. The study comprises image, spectral and electrical measurements, aiming to define and understand the operating domains of this plasma jet source. Two plasma zones were identified, which coexist: a long filament accompanied by a diffuse discharge. The coexistence of these plasma zones was studied in the power-mass flow rate parameter space. An electric model is proposed, considering the jet as a radiating antenna, which allows the determination of the main electrical parameters like capacitance, resistance and active RF power dissipated in the discharge. The specific zones on the I-V characteristics were assigned to the operating domains observed visually. The spectral emission of plasma has been used to characterize the jet in respect to the gas temperature, excitation temperature and plasma density.

  8. Fluorine and Oxygen Monitoring in Plasma CVM Etching Process for Silicon Wafer by Argon Actinometry Technique

    NASA Astrophysics Data System (ADS)

    Oshikane, Yasushi; Nagao, Akihiko; Yamamura, Kazuya; Oda, Akinori; Endo, Katsuyoshi

    2004-09-01

    Relative changes in the density of atomic fluorine and oxygen in plasma chemical vaporization machining (CVM) process is determined from the intensity ratios of the argon λ = 750 nm line, the atomic oxygen lines λ = 777 nm and 844 nm, and the atomic fluorine lines λ = 733 nm and 740 nm. The relative density change which depends on the position in the plasma is compared with an etched pattern on a silicon wafer surface. A rotational cylindrical electrode creates high speed shear flow of the plasma gas in a sub-millimeter gap between electrode and wafer. The plasma generation condition is controlled by changing VHF electric power and the rotation speed of electrode. The plasma gas composition is fixed at He/CF_4/O_2=99.89/0.1/0.01 and the total gas pressure is an atmosphere. The density profiles of fluorine and oxygen are different. In the basic experiment, the fluorine density profile has a maximum value around the narrowest plasma gap. On the other hand, the oxygen density profile has a peak up the gas flow. These results are compared with the etched pattern on the siliconsubstrate.

  9. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    NASA Astrophysics Data System (ADS)

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat

    2015-04-01

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (Te) and electron number density (ne) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10-17 - 10-18 m-3 where the electron temperature is between 1.00-2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  10. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    SciTech Connect

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  11. Aluminium metallisation of argon and oxygen plasma-modified polycarbonate thin film surfaces

    NASA Astrophysics Data System (ADS)

    Rastomjee, C. S.; Keil, M.; Sotobayashi, H.; Bradshaw, A. M.; Lamont, C. L. A.; Gador, D.; Umbach, E.

    1998-12-01

    The influence of plasma treatment on the metallisation of polycarbonate surfaces was studied using X-ray absorption spectroscopy (XAFS) and core level X-ray photoelectron spectroscopy (XPS). Thin films of two different molecules were chosen: bis-phenol-A polycarbonate with phenol endgroups (P-PC) prepared ex situ by the spin-coating technique onto MoTe 2{0001}surfaces, and the model compound bis-phenol-A polycarbonate ( n=1) with tert-butyl phenyl endgroups (tBP-PC) evaporated in situ in UHV onto Cu{110}, Ag{100} and Ag{111} surfaces with film thicknesses of up to several monolayers. Surfaces of untreated samples and of samples which were pre-treated with either an inert argon or a reactive oxygen microwave plasma were metallised with Al (evaporated by electron beam heating) at film thicknesses ranging from the sub-monolayer region up to several monolayers. For the untreated surface, XAFS and XPS spectra suggest that the Al reacts with the carbonate groups leading to a breaking of the CO double bonds (and/or a reduction in bond order) as well as formation of Al oxide, Al hydroxide and Al-O-C linkages. A study of the time-dependent oxidation of the evaporated Al leads to the conclusion that Al slowly diffuses to the reactive sites in the first few subsurface layers of the polymer. Argon plasma treatment of samples leads to a reduction in the number of carbonyl groups in the near surface region. After metal deposition a higher ratio of metallic, non-reacted, Al was observed covering the polycarbonate surface and the diffusion rate into the polymer bulk seems to be higher than in the case of the untreated surface. Oxygen plasma treatment leads to the creation of additional CO containing species which also react with the Al in the subsequent metallisation process. Here, the ratio of oxidised Al on the polymer surface is higher than observed for untreated and argon plasma pre-treated polymer surfaces.

  12. Spectroscopic evaluation of the effect of the microparticles on radiofrequency argon plasma

    NASA Astrophysics Data System (ADS)

    Mitic, S.; Y Pustylnik, M.; Morfill, G. E.

    2009-08-01

    Axial distributions of 1s excited states of argon were measured in a radiofrequency (RF) discharge by a self-absorption method. Experiments were performed in the PK-3+ chamber, designed for microgravity experiments in complex (dusty) plasmas on board the International Space Station. A correction of a standard self-absorption method for the extinction of the light by the levitating microparticles is proposed. Distributions, measured at the same discharge conditions in a microparticle-free discharge and a 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

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

    SciTech Connect

    Maya, L.

    1993-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    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.

  16. A Pulsing Argon Plasma Plume Excited by a Direct-Current Voltage

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Bao, Wenting; Jia, Pengying; Zhang, Chunyan; Li, Jiyuan

    2014-10-01

    In this study, by using a plasma jet driven by a direct-current voltage, a plasma plume can be generated in ambient air with argon used as the working gas. Through optical and electrical measurements, it is found that the plume discharge is pulsed despite the application of a direct-current voltage. The pulse frequency is investigated as a function of the sustaining voltage across the two electrodes and the gas flow rate. Differently from those of ordinary jets that usually operate in the bullet or continuous mode, the discharges of the direct-current jet almost volley at the same moment, while the quenching of the discharges propagates away from the jet nozzle.

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

    SciTech Connect

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

    1989-04-01

    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.

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

    SciTech Connect

    Qian Muyang; Ren Chunsheng; Wang Dezhen; Zhang Jialiang; Wei Guodong

    2010-03-15

    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.

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

    SciTech Connect

    Saikia, P. Goswami, K. S.; Saikia, B. K.

    2014-03-15

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

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

    NASA Astrophysics Data System (ADS)

    Saikia, P.; Goswami, K. S.; Saikia, B. K.

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Mendoza Gonzalez, Norma Yadira

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

  2. [The Characteristic Research of OH Induced by Water on an Argon Plasma Jet].

    PubMed

    Liu, Kun; Liao, Hua; Zheng, Pei-chao; Wang, Chen-ying; Liu, Hong-di; Danil, Dobrynin

    2015-07-01

    OH plays a crucial role in many fields, having aroused wide public concern in the world. Atmospheric Pressure Plasma Jet, which can be achieved by portable device due to working without the vacuum environment, has the advantages of high concentration of reactive species, high electron temperature and low gas temperature. It has become an important research topic in the field of gas discharge with a strong prospect. Especially, how to induce plasma jet to produce OH has become a new hotpot in the field of low-temperature plasma. It has been reported that mass OH can be induced successfully when water vapor is added to the working gas, but it will be unstable when the concentrate of water reaches a certain degree. Thus, a device of argon plasma jet with a Ring-to-Ring Electrode Configuration has been designed to interact with water in the surrounding air to generate OH under atmospheric pressure. In order to increase the production of OH, ultrasonic atomizing device is introduced to promote water concentration around the plasma plume. The generating rule of OH(A2J) induced by water has been extensively studied under different voltages and flow rate. OH output induced by the plasma has been tested by emission spectrometry, and at the meanwhile, Ar atomic spectral lines at 810.41 and 811.48 nm are also recorded in order to calculate the electron temperature in argon plasma plume. The results show that the water surrounding the plasma plume can be induced to produce OH, and OH(A2 ?+) output increases with the electrode voltage rising from 20 to 28 kV. When the flow rate increases from 100 to 200 L x h(-1), the OH(A2?+) output increases, but from 200 to 600 L x h(-1), it decreases. The production rules of OH(A2?+) is the same as that of electron temperature. Therefore, the presumption is proved that OH output mainly affected by electron temperature. PMID:26717727

  3. Estimating and controlling the atomic oxygen content in an argon-oxygen plasma

    NASA Astrophysics Data System (ADS)

    Keville, Bernard; Monahan, Derek D.; Turner, Miles M.

    2008-10-01

    Oxygen rich plasmas have been applied in many plasma processing applications for decades. In most such applications, process yield could be improved significantly by applying closed loop control of atomic oxygen radical concentration. The design of effective, real time, closed loop control algorithms is facilitated by simple dynamical models of the relationship between inputs, or actuators in control terminology, and the process quantities to be controlled. In the case of an oxygen rich plasma process, one requires the relationship between the inputs - flow-rate set points, forward power from the RF supply and residence time, for example - and the oxygen radical density. With the aid of an argon-oxygen plasma simulation, this presentation describes how, with the aid of simplified dynamical models of the process, one would design model-based control algorithms for the real-time, closed loop control of oxygen radical density. A sine qua non of real time, closed loop control is an accurate estimate of the process quantities to be controlled. Although actinometry provides a non-invasive method for estimating species densities, atomic oxygen actinometry is complicated by the fact that photon emission can occur through dissociative as well as direct excitation, leading to potential ambiguity between the emission intensity and the actual radical concentration in the plasma. Optimal estimation of process states given indirect measurements corrupted by process and measurement noise is a classical topic in control theory and has yielded some spectacular results, notably the ubiquitous Kalman filter.

  4. Laser scattering diagnostics of an argon atmospheric-pressure plasma jet in contact with vaporized water

    NASA Astrophysics Data System (ADS)

    Seo, B. H.; Kim, J. H.; You, S. J.; Seong, D. J.

    2015-12-01

    The radial profiles of the electron density, electron temperature, and molecular rotational temperature are investigated in an argon atmospheric-pressure plasma jet in contact with vaporized water, which is driven by a 13.56 MHz radio frequency by means of the Thomson and Raman laser scattering methods. There is a distinct difference in the radial profiles of the plasma parameters between plasmas in contact with water and those without water contact. In the case of plasmas without vaporized water contact, all the parameters have a single-peak distribution with maximum values at the center of the discharge. In the case of plasmas in contact with vaporized water, all parameters have double-peak distributions; a neighboring peak appears beside the main peak. The new peak may have originated from the ripple of the water surface, which works as a cathode, and the peak of the ripple offers a sharp curvature point, playing the role of a pin. Our experimental results and the underlying physics are described in detail.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    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).

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

    SciTech Connect

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

    2008-01-01

    Dusty plasmas consist of electrons, ions, neutrals and nm-μm 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 μm 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, λ = 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..

  7. Morphology and characteristics of laser-induced aluminum plasma in argon and in air: A comparative study

    NASA Astrophysics Data System (ADS)

    Bai, Xueshi; Cao, Fan; Motto-Ros, Vincent; Ma, Qianli; Chen, Yanping; Yu, Jin

    2015-11-01

    In laser-induced breakdown spectroscopy (LIBS), ablation takes place in general in an ambient gas of the atmospheric pressure, often in air but also in noble gas such as argon or helium. The use of noble gas is known to significantly improve the performance of the technique. We investigate in this work the morphology and the characteristics of induced plasma in argon and in air. The purpose is to understand the mechanism of the analytical performance improvement by the use of argon ambient with respective to air ambient and the dependence on the other experimental parameters such as the laser fluence. The observation of plasma morphology in different ambient gases provides also information for better design of the detection system which optimizes the signal collection according to the used ambient gases. More specifically, the expansion of the plasma induced on an aluminum target with nanosecond infrared (1064 nm) laser pulse in two ambient gases, argon and the atmospheric air, has been studied with spectroscopic imaging at short delays and with emission spectroscopy at longer delays. With relatively low ablation laser fluence (65 J/cm2), similar morphologies have been observed in argon and in air over the early stage of plasma expansion, while diagnostics at longer delay shows stronger emission, higher electron density and temperature for plasma induced in argon. With higher ablation laser fluence (160 J/cm2) however, different expansion behaviors have been observed, with a stagnating aluminum vapor near the target surface in air while a propagating plume away from the target in argon. The craters left on the target surface show as well corresponding difference: in air, the crater is very shallow with a target surface chaotically affected by the laser pulse, indicating an effective re-deposition of the ablated material back to the crater; while in Ar a deeper crater is observed, indicating an efficient mass removal by laser ablation. At longer delays, a brighter, denser and hotter plasma is always observed in argon than in air as with lower ablation laser fluences. The observed different influences of the ambient gas on the plasma expansion behavior for different laser fluences are related to the different modes of laser-supported absorption waves, namely laser-supported combustion (LSC) wave and laser-supported detonation (LSD) wave.

  8. Simulation of DBD plasma actuators, and nanoparticle-plasma interactions in argon-hydrogen CCP RF discharges

    NASA Astrophysics Data System (ADS)

    Mamunuru, Meenakshi

    The focus of this work is modeling and simulation of low temperature plasma discharges (LTPs). The first part of the thesis consists of the study of dielectric barrier (DBD) plasma actuators. Use of DBD plasma actuators on airfoil surfaces is a promising method for increasing airfoil efficiency. Actuators produce a surface discharge that causes time averaged thrust in the neutral gas. The thrust modifies the boundary layer properties of the flow and prevents the occurrence of separation bubbles. In simulating the working of an actuator, the focus is on the spatial characteristics of the thrust produced by the discharge over very short time and space scales. The results provide an understanding of the causes of thrust, and the basic principles behind the actuator operation. The second part of this work focusses on low pressure plasma discharges used for silicon nanoparticle synthesis. When reactive semiconductor precursor gases are passed through capacitively coupled plasma (CCP) radio frequency (RF) reactors, nano sized particles are formed. When the reactors are operated at high enough powers, a very high fraction of the nanoparticles are crystallized in the chamber. Nanoparticle crystallization in plasma is a very complex process and not yet fully understood. It can be inferred from experiments that bulk and surface processes initiated due to energetic ion impaction of the nanoparticles are responsible for reordering of silicon atoms, causing crystallization. Therefore, study of plasma-particle interactions is the first step towards understanding how particles are crystallized. The specific focus of this work is to investigate the experimental evidence that hydrogen gas presence in argon discharges used for silicon nanocrystal synthesis, leads to a superior quality of nanocrystals. Influence of hydrogen gas on plasma composition and discharge characteristics is studied. Via Monte Carlo simulation, distribution of ion energy impacting particles surface is studied. It is seen that hydrogen ions cause a reduction in particle floating potential, thereby lowering the ion impaction energies. The hydrogen ion current is also effective in delivering increased number of atomic H radicals to the particle surface, which are known to promote particle crystallization. The work therefore sheds light on the ways in which trace amount of hydrogen gas participates in silicon nanoparticle crystallization in argon silane plasma.

  9. Surface modification of argon/oxygen plasma treated vulcanized ethylene propylene diene polymethylene surfaces for improved adhesion with natural rubber

    NASA Astrophysics Data System (ADS)

    Basak, Ganesh C.; Bandyopadhyay, Abhijit; Neogi, Sudarsan; Bhowmick, Anil K.

    2011-01-01

    Vulcanized ethylene propylene diene polymethylene (EPDM) rubber surface was treated in a radio frequency capacitatively coupled low pressure argon/oxygen plasma to improve adhesion with compounded natural rubber (NR) during co-vulcanization. The plasma modified surfaces were analyzed by means of contact angle measurement, surface energy, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray sulfur mapping and atomic force microscopy. Several experimental variables such as plasma power, length of exposure time and composition of the argon-oxygen gas mixture were considered. It was delineated that plasma treatment changed both surface composition and roughness, and consequently increased peel strength. The change in surface composition was mainly ascribed to the formation of C-O and -Cdbnd O functional groups on the vulcanized surfaces. A maximum of 98% improvement in peel strength was observed after plasma treatment.

  10. Improved properties of oxygen and argon RF plasma-activated polyester fabrics loaded with TiO2 nanoparticles.

    PubMed

    Mihailović, Darka; Saponjić, Zoran; Molina, Ricardo; Puac, Nevena; Jovancić, Petar; Nedeljković, Jovan; Radetić, Maja

    2010-06-01

    The potentials of low-pressure capacitively coupled RF oxygen and argon plasmas for the activation of polyester fibers surface that can enhance the deposition of colloidal TiO(2) nanoparticles were discussed. SEM and XPS analysis confirmed the plasma-induced morphological and chemical changes on the surface of polyester fibers. Oxygen and argon plasma pretreated polyester fabrics loaded with TiO(2) nanoparticles provided maximum reduction of Gram-negative bacteria E. coli and UV blocking. The self-cleaning effects tested on blueberry juice stains and photodegradation of methylene blue in aqueous solution proved excellent photocatalytic activity of TiO(2) nanoparticles deposited onto fiber surface. Although both plasmas significantly contributed to overall improvement of properties of such nanocomposite textile material, oxygen plasma treatment, in particular, enhanced the deposition of colloidal TiO(2) nanoparticles and thus ensured superior effects. PMID:20524631

  11. The influence of the EUV spectrum on plasma induced by EUV radiation in argon and hydrogen gas

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Plasmas induced by EUV radiation are scarcely investigated, although they are unique since they are created without any discharge. These plasmas are also of interest from an applicational point of view, since they are related to the lifetime of optics in EUV lithography tools. In order to assess this impact, it is essential to characterize and understand EUV-induced plasma. In this contribution the influence of the background gas (argon and hydrogen) in the lithography tool and the spectrum of the illumination source on the electron density of EUV-induced plasma is investigated using microwave cavity resonance spectroscopy. The experimental results showed that out-of-band radiation (>20 nm) is the main contributor to EUV-induced plasma in both argon and hydrogen. In hydrogen, this contribution is relatively more important than in argon due to the stronger wavelength dependence of the photoionization cross section of hydrogen than of argon. Furthermore, the production of electrons by out-of-band radiation lasts longer than the production by in-band radiation (10–20 nm) due to the longer temporal width of out-of-band radiation. Finally, the obtained results correspond reasonably well with estimates from a simplified absorption model.

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

    NASA Astrophysics Data System (ADS)

    Baeva, M.; Andrasch, M.; Ehlbeck, J.; Loffhagen, D.; Weltmann, K.-D.

    2014-04-01

    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.

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

    SciTech Connect

    Baeva, M. Andrasch, M.; Ehlbeck, J.; Loffhagen, D.; Weltmann, K.-D.

    2014-04-14

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

  14. Laser light scattering from silicon particles generated in an argon diluted silane plasma

    NASA Astrophysics Data System (ADS)

    Qin, Y.; Kortshagen, U. R.; Aydil, E. S.

    2016-03-01

    We conducted laser light scattering (LLS) measurements in a 13.56 MHz capacitively coupled dusty plasma maintained in silane and argon to study the spatial distribution of silicon nanoparticles and nanoparticle agglomerates. Specifically, we focused on the temporal evolution of their spatial distribution in the plasma as a function of pressure and power. We observed three distinct types of temporal evolution behavior of the nanoparticle dust cloud in the plasma and classified these into three regimes based on pressure and power. Each regime features a distinct pattern in laser light scattering measurements. At low pressures (∼80–100 mTorr) and high powers (∼40–60 W) we observed periodically repeating expansions and contractions of a continuous dust cloud for the first time. Dust voids, which have been reported before, were also observed at high pressures (∼100–150 mTorr) and low powers (∼20–40 W) in the center of the plasma. A mechanism is proposed to explain the observed dynamics of the nanoparticles. The balance between the ion drag force and electrostatic forces and their dependence on particle size are hypothesized to be the dominant factors that determine the nanoparticle cloud dynamics.

  15. Modelling of carbon dust formation by cluster growth in argon plasmas

    NASA Astrophysics Data System (ADS)

    Bonnin, X.; Lombardi, G.; Hassouni, K.; Michau, A.; Bndic, F.; Arnas, C.

    2007-06-01

    In tokamaks with carbon plasma-facing components, one can observe the presence of nano-sized dust particles. Understanding such dust particle formation is a prerequisite to any attempt to limit or avoid this dust that may be responsible for tritium retention and pollution of the plasma. We report on coupled modeling of carbon chemistry and dust particle nucleation, growth, and transport in a plasma discharge. The chemical model used for carbon cluster dust growth is described in detail. The results are consistent with measurements made at LPIIM from low-pressure argon DC discharges in a stainless steel reactor with a graphite cathode [C. Arnas, C. Dominique, P. Roubin et al., J. Nucl. Mater. 337-339 (2005) 69], serving as a proxy for the tokamak plasma edge. The time evolution of the 'large' dust particles consists of a nucleation phase followed by an accretion phase. These reach a dust grain size of 40 nm on a timescale comparable to the experimental observations (minutes to hours).

  16. Generation of strongly coupled plasma using Argon-based capillary discharge lasers

    NASA Astrophysics Data System (ADS)

    Rossall, Andrew K.; Aslanyan, Valentin; Wilson, Sarah; Tallents, Gregory J.

    2015-09-01

    Argon based capillary discharge lasers operate in the extreme ultra violet (EUV) at 46.9 nm with an output of up to 0.5 mJ energy per pulse and up to a 10 Hz repetition rate. Focussed irradiances of up to 1012 W cm-2 are achievable and can be used to generate plasma in the warm dense matter regime by irradiating solid material. To model the interaction between such an EUV laser and solid material, the 2D radiative-hydrodynamic code POLLUX has been modified to include absorption via direct photo-ionisation, a super-configuration model to describe the ionisation dependant electronic configurations and a calculation of plasma refractive indices for ray tracing of the incident EUV laser radiation. A simulation study is presented, demonstrating how capillary discharge lasers of 1.2ns pulse duration can be used to generate strongly coupled plasma at close to solid density with temperatures of a few eV and energy densities up to 1×105 J cm-3. Plasmas produced by EUV laser irradiation are shown to be useful for examining the equation-of-state properties of warm dense matter. One difficulty with this technique is the reduction of the strong temperature and density gradients which are produced during the interaction. Methods to inhibit and control these gradients will be examined.

  17. Study of a contracted glow in low-frequency plasma-jet discharges operating with argon

    NASA Astrophysics Data System (ADS)

    Minotti, F.; Giuliani, L.; Xaubet, M.; Grondona, D.

    2015-11-01

    In this work, we present an experimental and theoretical study of a low frequency, atmospheric plasma-jet discharge in argon. The discharge has the characteristics of a contracted glow with a current channel of submillimeter diameter and a relatively high voltage cathode layer. In order to interpret the measurements, we consider the separate modeling of each region of the discharge: main channel and cathode layer, which must then be properly matched together. The main current channel was modeled, extending a previous work, as similar to an arc in which joule heating is balanced by lateral heat conduction, without thermal equilibrium between electrons and heavy species. The cathode layer model, on the other hand, includes the emission of secondary electrons by ion impact and by additional mechanisms, of which we considered emission due to collision of atoms excited at metastable levels, and field-enhanced thermionic emission (Schottky effect). The comparison of model and experiment indicates that the discharge can be effectively sustained in its contracted form by the secondary electrons emitted by collision of excited argon atoms, whereas thermionic emission is by far insufficient to provide the necessary electrons.

  18. Measurements of neutral plasma species in an argon/isopropyl alcohol plasma for the deposition of organic films

    NASA Astrophysics Data System (ADS)

    Guerin, Daniel C.; Fernsler, Richard F.; Shamamian, Vasgen A.

    2003-09-01

    The neutral gas-phase chemistry of an isopropyl alcohol/argon pulsed plasma was investigated. Appearance potential mass spectrometry was used to identify the neutral species present in the plasma. This article complements the previously published study of the positive ion flux to the deposition surface. Of particular interest was the identification of the reactive species in the plasma that exist as neutrals as well as ions. We determined that neutral radicals were produced by hydrogen-exchange mechanisms as well as electron-impact dissociation reactions. The electron-impact dissociation ionization of the precursor in the plasma resulted in reactive ions that did not occur as neutral species. A byproduct of this reaction was a large concentration of the neutral methyl radical. At low pressures, the methyl radicals diffuse to the surface and are incorporated into the deposited films. At elevated pressures, the neutral methyl radicals abstract hydrogen from gas-phase isopropyl alcohol molecules to form methane. Furthermore, as the pressure increases, the plasma becomes more remote from the deposition surface. Molecular ions created in the remote discharge preserve their chemical identity while diffusing to the surface, since the energies of charge-exchange limit the extent of reaction with the precursor.

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

    PubMed

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

    2011-03-15

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

  20. Radiative properties of argon-helium-nitrogen-carbon-cobalt-nickel plasmas used in CNT synthesis

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  1. Application of a hybrid collisional radiative model to recombining argon plasmas

    NASA Astrophysics Data System (ADS)

    Benoy, D. A.; van der Mullen, J. A. M.; van de Sanden, M. C. M.; van der Sijde, B.; Schram, D. C.

    1993-02-01

    A collisional radiative model, in which a hybrid cut-off technique is used, is applied to recombining plasmas to study the atomic state distribution (ASDF) and the recombination coefficient. Computations of the ASDF using semi-empirical rate coefficients of Vriens and Smeets (V-S) and Drawin (D) are compared with experimental values measured at various positions in a free expanding argon arc jet. Apart from the shock position, where the calculated results are too low, the model calculations are higher than the experimental results. The volumetric recombination coefficient has a Te exp -4 and a Te exp -4.8 dependence when semiempirical rate coefficients of, respectively, V-S and D are used. The differences between the models based on the rate coefficients of V-S and D indicate that the recombination flow is sensitive to the low temperature behavior of the rate coefficients.

  2. Sulphate analysis in uranium leach iron(III) chloride solutions by inductively coupled Argon Plasma Spectrometry.

    PubMed

    Nirdosh, I; Lakhani, S; Yunus, M Z

    1993-02-01

    Inductively coupled Argon Plasma Spectrometry is used for the indirect determination of sulphate in iron(III) chloride leach solution of Elliot Lake uranium ores via addition of a known amount of barium ions and analyzing for excess of barium. The ore contains approximately 7 wt% pyrite, FeS(2) as the major mineral which oxidizes to generate sulphate during leaching with fe(III). The effects of pH, the concentrations of Fe(III) and chloride ions and for presence of ethanol in the test samples on the accuracy of analysis are studied. It is found that unlike the Rhodizonate method, removal of iron(III) from or addition of ethanol to the test sample prior to analysis are not required. Linear calibration curves are obtained. PMID:18965613

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

    SciTech Connect

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

    1984-11-01

    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.

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

    SciTech Connect

    Mohammadnejad, M.; Pestehe, S. J.; Mohammadi, M. A.; Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz

    2013-07-15

    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.

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

    SciTech Connect

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

    2014-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    EPA Science Inventory

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

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

    SciTech Connect

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

    1982-10-01

    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.

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

    SciTech Connect

    Srivastava, Nimisha; Wang Chuji

    2011-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Srivastava, Nimisha; Wang, Chuji

    2011-09-01

    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.

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

    SciTech Connect

    Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing; Duan Yixiang; Research Center of Analytical Instrumentation, Sichuan University, Chengdu 610064

    2013-01-21

    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.

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

    SciTech Connect

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

    2006-05-01

    A capacitively coupled, atmospheric pressure plasma has been developed that produces a high concentration of reactive species at a gas temperature below 300 deg. 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{+-}0.4x10{sup 17} cm{sup -3}, using 6.0 vol % O{sub 2} in argon at 150 W/cm{sup 3}. The ozone concentration determined at the same conditions was 4.3{+-}0.5x10{sup 14} cm{sup -3}. A model of the gas phase reactions was developed and yielded O atom and O{sub 3} concentrations in agreement with experiment. This plasma source etched Kapton registered at 5.0 {mu}m/s at 280 deg. 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.

  13. Factor XII-independent activation of factor XI in plasma: effects of sulfatides on tissue factor-induced coagulation.

    PubMed

    Gailani, D; Broze, G J

    1993-08-01

    Factor XI (FXI) may be activated in a purified system by thrombin and by autoactivation in the presence of negatively charged substances such as dextran sulfate or sulfatides. The current studies were performed to determine if these processes occur during the coagulation of plasma. FXII--deficient plasma was supplemented with 125I-FXI and clot formation was induced with tissue factor and/or sulfatides. Cleavage of FXI was studied by standard polyacrylamide gel electrophoresis and autoradiography. Activated FXI (FXIa) was detected after 20 minutes of incubation with sulfatides alone and this process was markedly accelerated by the addition of tissue factor (TF). The enhancing effect of TF was blocked by hirudin, which indicated thrombin involvement in FXI activation. The contribution of FXIa to FIX activation in this system was studied using a 3H-FIX activation peptide release assay. Sulfatides increased FIX activation about twofold in plasma induced to clot with TF but had no effect if the plasma was immunodepleted of FXI. FIX activation was also increased in plasma induced to clot with FXa if sulfatides were present. The enhanced generation of FIXa was dependent on FXI and was blocked by hirudin. Some activation was seen in the reactions with sulfatides and hirudin and is likely solely caused by FXI autoactivation. The data indicate that during the coagulation of plasma in the presence of sulfatides, FXI is activated by a mechanism that is thrombin dependent and does not require FXII. PMID:8338946

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

    NASA Astrophysics Data System (ADS)

    Wendt, M.

    2011-03-01

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

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

    SciTech Connect

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

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    PubMed Central

    Hess, Katharina; Ajjan, Ramzi; Phoenix, Fladia; Dob, Jzsef; Gl, Pter; Schroeder, Verena

    2012-01-01

    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. PMID:22536427

  18. Presheath and Double Layer Structures in an Argon Helicon Plasma Source

    NASA Astrophysics Data System (ADS)

    Siddiqui, M. Umair

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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 COH 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.

  20. Spatially resolved measurement of hydroxyl radical (OH) concentration in an argon RF plasma jet by planar laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Voráč, J.; Obrusník, A.; Procházka, V.; Dvořák, P.; Talába, M.

    2014-04-01

    A spatially resolved two-dimensional quantitative measurement of OH concentration in an effluent of a radio-frequency-driven atmospheric pressure plasma jet ignited in argon is presented. The measurement is supported by a gas dynamics model which gives detailed information about the spatially resolved gas composition and temperature. The volume in which the OH radicals were found and partially also the total amount of OH radicals increase with the argon flow rate, up to a value for which the flow becomes turbulent. In the turbulent regime, both the emission from the jet and the OH concentration are confined to a smaller volume. The maximum concentration of about 5.4 × 1021 m-3 is reached at the tip of the visible discharge at the flow rate of 0.6 slm and high driving powers. An increase in hydroxyl concentration due to admixing of humid ambient air to the argon flow was observed.

  1. [A role of some intracellular signaling cascades in planarian regeneration activated under irradiation with low-temperature argon plasma].

    PubMed

    Ermakov, A M; Ermakova, O N; Maevski?, E I

    2014-01-01

    Using inhibitory analysis the role of some intracellular signaling pathways in activation of planarian regeneration under the influence of low-temperature argon plasma (LTAP) has been investigated. Inactivation of specific inhibitors of intracellular signaling enzymes such as the receptor tyrosine kinase (EGFR), TGF ? receptor, calmodulin, adenylate cyclase, phospholipase A2, phospholipase C, cyclin-dependent protein kinase, JAK2-protein kinase, JNK-protein kinase MEK-protein kinase led to inhibition of the head growth during its regeneration in planarians. Pretreatment with LTAP irradiation provided no inhibitory action of some cascades regulating proliferation. However, the inhibitors of the key regulators of regeneration: TGF ? receptor, calmodulin and MEK-protein kinase completely suppressed the activating effect of plasma. Thus, by the example of regenerating planarians it is shown, that biological activity of low-temperature argon plasma LTAP is caused by modulation of a plurality of cellular signaling systems. PMID:25715600

  2. Vacuum ultraviolet photon fluxes in argon-containing inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Radovanov, S. B.; Persing, H. M.; Wang, S.; Culver, C. L.; Boffard, J. B.; Lin, C. C.; Wendt, A. E.

    2013-09-01

    Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. Damage of materials is induced by energy transfer from the VUV photons to the surface, causing disorder in the surface region, surface reactions, and affecting bonds in the material bulk. Monitoring of the surface flux of VUV photons from inductively coupled plasmas (ICP) and its dependence on discharge parameters is thus highly desirable. Results of non-invasive, direct windowless VUV detection using a photosensitive diode will be presented. Relative VUV fluxes were also obtained using a sodium salicylate coating on the inside of a vacuum window, converting VUV into visible light detected through the vacuum window. The coating is sensitive to wavelengths in the range 80-300 nm, while the photodiode is only sensitive to wavelengths below 120 nm. In argon the VUV emissions are primarily produced by spontaneous decay from 3p5 4 s resonance levels (1s2,1s4) and may be reabsorbed by ground state atoms. Real-time resonance level concentrations were measured and used to predict the VUV photon flux at the detector for a range of different ICP pressures, powers, and for various admixtures of Ar with N2, and H2. This work was supported in part by NSF grant PHY-1068670.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  4. Discharge processes and an electrical model of atmospheric pressure plasma jets in argon

    NASA Astrophysics Data System (ADS)

    Fang, Zhi; Shao, Tao; Yang, Jing; Zhang, Cheng

    2016-01-01

    In this paper, an atmospheric pressure plasma discharge in argon was generated using a needle-to-ring electrode configuration driven by a sinusoidal excitation voltage. The electric discharge processes and discharge characteristics were investigated by inspecting the voltage-current waveforms, Lissajous curves and lighting emission images. The change in discharge mode with applied voltage amplitude was studied and characterised, and three modes of corona discharge, dielectric barrier discharge (DBD) and jet discharge were identified, which appeared in turn with increasing applied voltage and can be distinguished clearly from the measured voltage-current waveforms, light-emission images and the changing gradient of discharge power with applied voltage. Based on the experimental results and discharge mechanism analysis, an equivalent electrical model and the corresponding equivalent circuit for characterising the whole discharge processes accurately was proposed, and the three discharge stages were characterised separately. A voltage-controlled current source (VCCS) associated with a resistance and a capacitance were used to represent the DBD stage, and the plasma plume and corona discharge were modelled by a variable capacitor in series with a variable resistor. Other factors that can influence the discharge, such as lead and stray capacitance values of the circuit, were also considered in the proposed model. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

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

    NASA Astrophysics Data System (ADS)

    Killer, Carsten; Mulsow, Matthias; Melzer, Andr

    2015-04-01

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

  6. Properties of an argon plasma free jet generated from a continuous optical discharge

    NASA Astrophysics Data System (ADS)

    Lebhot, A.; Campargue, R.

    1996-07-01

    The expansion of a supersonic free jet generated from a laser-sustained argon plasma is studied experimentally by using two techniques: (i) the time-of-flight analysis of velocity distributions of the atom beam skimmed from the free jet, leading to the conclusion that the translational relaxation of the heavy particles (neutral atoms and ions) follows very accurately the classical isentropic laws; (ii) the fluorescence technique for studying the internal state relaxation process by local analysis of the radiation emitted spontaneously from the plasma free jet. Only the electronic states excited above 14.5 eV are found to be in a Boltzmann equilibrium, defining a local temperature Texcit in the structure of the free jet. The axial electronic temperature, calculated using a simple one-dimension thermodynamic model, follows fairly well the experimental values of Texcit, while the translational temperature of the heavy particles decreases much lower, in agreement with the asymptotic value deduced from the velocity distributions of the atom beam. Thus appears the uncoupling between the electronic excitation process, governed by the electronic collisions, and the translational cooling of the heavy particles, governed by the collisions between the heavy particles. A more detailed analysis of the excitation process is obtained through the calculation of the state population densities with a collisional-radiative model. The agreement with the experimental measurements is rather good for most of the states investigated.

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

    PubMed Central

    Kim, Sung Chul; Cho, Ki Hong

    2012-01-01

    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 7.41.4, while the final follow-up VAS score was 1.40.7 (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. Conclusion PDCT is a safe and efficient treatment modality in a selective patient with HLD. PMID:22396836

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

    PubMed Central

    Traba, Christian; Liang, Jun F.

    2014-01-01

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

  9. Bacterial inactivation/sterilization by argon plasma treatment on contaminated titanium implant surfaces:In vitro study

    PubMed Central

    Annunziata, Marco; Donnarumma, Giovanna; Caputo, Pina; Nastri, Livia; Guida, Luigi

    2016-01-01

    Background Surface treatment by argon plasma is widely used as the last step of the manufacturing process of titanium implant fixtures before their sterilization by gamma rays. The possibility of using such a technology in the daily clinical practice is particularly fascinating. The aim of the present study was to assess the effects of the argon plasma treatment on different titanium implant surfaces previously exposed In vitro to bacterial contamination. Material and Methods Sterile c.p. titanium implant discs with turned (T, Sa: 0.8 µm ), sandblasted/acid-etched (SAE, Sa: 1.3 µm) and titanium plasma sprayed (TPS, Sa: 3.0µm) surface were used in this study. A strain of Aggregatibacter actinomycetemcomitans ATCC3718 was grown at 37°C under anaerobic conditions for 24 h and then transferred on six discs for each of the three surface types. After 24 hours, a half of the contaminated discs (control group) were directly used to evaluate the colony forming units (CFUs). The other half of the contaminated discs (test group) were treated in an argon plasma chamber for 12 minutes at room temperature prior to be analyzed for CFU counting. All assays were performed using triplicate samples of each material in 3 different experiments. Results When the CFU counting was carried out on control discs, a total of 1.50x106±1.4x105, 1.55x106±7.07x104 and 3.15x106±2.12x105 CFU was respectively assessed for T, SAE and TPS discs, without statistically significant differences among the three surfaces. On the contrary, any trace of bacterial contamination was assessed for titanium discs treated in the argon plasma chamber prior to be analyzed, irrespectively to the implant surface tested. Conclusions Within the limit of this study, reported data suggested that the argon plasma technology could be efficiently used to decontaminate/sterilize previously infected titanium implant surfaces. Key words:Argon plasma, titanium implant surface, Aggregatibacter actinomycetemcomitans. PMID:26595834

  10. Observation of forward breakdown mechanism in high-pressure argon plasma produced by irradiation by an excimer laser

    SciTech Connect

    Tsuda, N.; Yamada, J.

    1997-01-01

    When a XeCl excimer laser beam was focused in a high-pressure argon gas up to 150 atm, a hot and dense plasma was produced at the focal spot. The plasma developed not only backward but also forward, which differed from one produced by a visible laser. The radius of the forward plasma became smaller beyond the focal spot. There had been no explanation for the development mechanism of the forward plasma. A new model for the forward development mechanism called a forward breakdown wave was proposed. The forward plasma was calculated assuming that the laser beam transmitted through the plasma was further focused by the plasma. This model could predict the forward development behavior considerably well. {copyright} {ital 1997 American Institute of Physics.}

  11. Determining the effect of freezing on coagulation testing: comparison of results between fresh and once frozen-thawed plasma.

    PubMed

    Gosselin, Robert C; Dwyre, Denis W

    2015-01-01

    The accuracy of the results from coagulation testing can be affected by numerous preanalytic and analytic variables including the stability of the citrated sample at room temperature. Samples not tested within 2-4?h of collection should be processed and frozen for later analysis. As limited data exist about the impact of freezing samples on coagulation testing, we sought to evaluate the effect of freezing on coagulation testing. Plasma samples into 3.2% sodium citrate tubes, centrifuged to yield platelet-poor plasma, were evaluated for prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, D-dimer, antithrombin (AT) activity, factors V, VII, VIII, IX, lupus anticoagulant and anti-Xa measurements for both unfractionated and low-molecular-weight heparins. Samples were then frozen at -70C for at least 1 week and testing was repeated using the same lot of material. All tests strongly correlated (R?>?0.85) between fresh and frozen sample results. Using paired t test analysis, significant differences between fresh and frozen tested plasma existed for PT, APTT, factors V, VIII and AT. Significant differences existed between fresh and frozen lupus anticoagulant ratios (lupus anticoagulant screen but not lupus anticoagulant confirm), and single centrifugation process underestimated the presence of lupus anticoagulant as compared to double centrifugation processing. Freezing significantly affects the results for PT, APTT, factors V and VIII activity, and AT activity, although these differences were not considered to be clinically significant. Double centrifugation is required for accurate lupus anticoagulant testing, regardless of whether platelet-poor plasma is achieved with single centrifugation. PMID:25202883

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

    SciTech Connect

    Lee, Young Wook; Lee, Hye Lan; Chung, T. H.

    2011-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  14. The study of FTO surface texturing fabrication using Argon plasma etching technique for DSSC applications

    NASA Astrophysics Data System (ADS)

    Jayanti, Lindha; Kusumandari; Sujitno, Tjipto; Suryana, Risa

    2016-02-01

    This paper is aimed to investigate the fabrication of the fluorine-doped tin oxide (FTO) texturing by using Argon (Ar) plasma etching. The pressure and temperature of Ar gas during plasma etching were 1.6 mbar and 240-285oC, respectively. The plasma etching time was varied from 3 and 10 min. We also prepared without etching samples as reference. UV-Vis spectrophotometer showed that the transmittances of etching samples are higher than the without etching samples. The root mean square roughness (Rq) of etching samples are lower than the without etching samples. It is considered that the Ar ions bombardment can modify the FTO surfaces. However, the etching time does not significantly affect the FTO surfaces for 3 min and 10 min. The Rq of the without etching sample, the etching sample for 3 min, and the etching sample for 10 min are 11.697 nm, 9.859 nm, and 9.777 nm, respectively. These results are good agreement with the four point probe measurement that indicated that the sheet resistance (RS) for each the without sample, the etching sample for 3 min, and the etching sample for 10 min are 16.817 Ωsq, 16.067 Ω/sq, and 15.990 Ω/sq. In addition, the optical transmittance of the etching sample for 3 min and the etching sample for 10 min at wavelengths of 350 - 850 nm are almost similar. This is evidence that the etching time below 10 min cannot significantly change the morphology, optical and electrical properties.

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

    SciTech Connect

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

    1993-01-01

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

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

    SciTech Connect

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

    1993-04-01

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

  17. Surface modification of polypropylene (PP) using single and dual high radio frequency capacitive coupled argon plasma discharge

    NASA Astrophysics Data System (ADS)

    Akbar, D.

    2016-01-01

    Single (40.68 MHz) and dual (40.68/2.1 MHz) high radio frequency (RF) argon plasma discharge was employed as a source of a low-temperature treatment mechanism that was used to modify the surface of polypropylene (PP). The effects of argon plasma on the surface chemistry and the surface morphology of PP were studied using X-ray diffraction analyses. In this study, samples were treated under different plasma operation conditions for parameters such as RF power, gas pressure and treatment time. Furthermore, the crystallite size was calculated (using Scherrer equation) from the diffraction pattern of the β fraction (Full Width at Half maximum) for PP samples. The results reveal that the crystallite size strongly increases with RF power and treatment time, but decreases with gas pressure. From the analysis, it was found that the treated samples have higher crystallite sizes in compared to those of the single RF plasma discharge. This happens because the increase of plasma temperature leads to increases in the crystallization of PP sample, so that the crystallite size also increases. Furthermore, because of the advantageous features of the dual-RF plasma mode, the surface modification of PP sample can occur more quickly than is possible via the single-RF plasma discharge.

  18. The Mechanisms of Coagulation.

    ERIC Educational Resources Information Center

    Kurtz, Richard; Jesty, Jolyon

    1994-01-01

    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)

  19. Temperature measurements in microwave argon plasma source by using overlapped molecular emission spectra

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, E.; Bazavan, M.; Shindo, H.

    2015-09-01

    The electron excitation temperature Texc, vibrational Tvib, and rotational Trot temperatures were measured in a high-pressure line-shaped microwave plasma source in argon over a wide range of gas pressure and microwave power, by using optical emission spectra. The selected ArI transition lines 5p-4s and 4p-4s were chosen to calculate electron excitation temperature using Boltzmann's plot method. Meanwhile, the emission spectra of hydroxyl OH molecular ( A 2 Σ + - X 2 Π i , Δ ν = 0 ) band and the nitrogen N2 second positive system ( C 3 Π u - B 3 Π g , Δ ν = + 1 ), both second diffraction order, were used to evaluate the vibrational Tvib and rotational Trot temperatures using the method of comparing the measured and calculated spectra with a chi-squared minimization procedure. The components of the overlapped spectrum are greatly influenced by the gas pressure; however, they are independent on microwave power. For temperatures, it was found that the Texc dramatically decreases from 2.5 to 0.75 eV, which qualitatively agrees with T e deduced from zero-global model. Both of Tvib and Trot significantly decrease with as gas pressure increase from 0.4 to 50 Torr. Yet, they behave differently with microwave power.

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

    SciTech Connect

    Zhang Qian; Wang Ruixue; Sun Peng; Feng Hongqing; Liang Yongdong; Zhu Weidong; Becker, Kurt H.; Zhang Jue; Fang Jing

    2012-06-15

    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.

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

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoquan; Yin, Zhixiang; Chen, Minggong; Hong, Lingli; Xia, Guangqing; Hu, Yelin; Huang, Yourui; Liu, Minghai; Kudryavtsev, A. A.

    2014-10-01

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

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

    SciTech Connect

    Chen, Zhaoquan; Yin, Zhixiang Chen, Minggong; Hong, Lingli; Hu, Yelin; Huang, Yourui; Xia, Guangqing; Liu, Minghai; Kudryavtsev, A. A.

    2014-10-21

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

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

    SciTech Connect

    Li Shouzhe; Huang Wentong; Zhang Jialiang; Wang Dezhen

    2009-07-15

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

  4. Comparative Histology of Plasma Treated Tissue

    NASA Astrophysics Data System (ADS)

    Rick, Kyle

    2009-10-01

    Atmospheric plasmas applied in surgical settings have unique characteristics found in histological results from animal tissue studies. This is evident in both ex vivo bench tissue tests and in vivo fresh tissue. Examples of these histological features are presented as results of a comparative study between plasma treated, common medical argon coagulation, and electrosurgery.

  5. Effect of Addition of Water Vapor on OH Radical Concentration in an Atmospheric Pressure Microwave Argon Plasma Jet

    NASA Astrophysics Data System (ADS)

    Srivastava, Nimisha; Wang, Chuji; Harper, Sterling

    2010-11-01

    In recent years, role of reactive plasma species such as OH and O in various plasma treatments and combustion applications are topics of investigation and debate. Quantitative study of OH radicals in atmospheric plasma jets can contribute to the better understanding of OH generation mechanism and to optimization of plasma treatment processing and plasma source designs. A 2.45 GHz microwave plasma source was used to study the effect on OH radical generation in an argon atmospheric pressure plasma jet with addition of H2O vapor. OH radical number densities were measured along the plasma jet axis using UV cavity ringdown spectroscopy of OH (A--X) (1 -- 0) band at 308 nm. Addition of water vapor results in reduction of plasma column jet length and increases gas temperature. Optical emission spectroscopy clearly shows that dominant reactive species in pure Ar plasma jet changed from N2 to OH with the addition of water vapor. The absolute number densities of OH varied along the jet axis from 7.4x10^14 to 3.7x10^16, 4.3x10^14 to 5.0x10^16, and 4.6x10^14 to 3.4x10^16 molecule/cm^3 for the addition of 0 ppm, 4 ppm, and 7 ppm water vapor, respectively.

  6. [Influence of pressure on plasma temperature in air/argon dielecteic barrier discharge].

    PubMed

    Dong, Li-Fang; Qi, Yu-Yan; Li, Li-Chun; Hao, Ya-Juan; Gao, Rui-Ling; Zhao, Zeng-Chao; Li, Xue-Chen

    2008-01-01

    Electron excitation temperature and molecule vibrational temperature in argon/air dielectric barrier discharge (DBD) at different gas pressure with water electrodes were studied by using optical emission spectra. The spectral lines of Ar I 763. 51 nm(2P6 --> 1S5) and Ar I 772.42 nm(2P2 --> 1S3) were chosen to calculate electron excitation temperature by the relative intensity ratio method. The emission spectra of nitrogen band of second positive system ( C3 pi(u) --> B3 pi(g)) were measured at the same time. The molecule vibration temperature was estimated by the emission intensities of different bands with delta(nu) = -1, delta(nu) = -2, and delta(nU) = -3 in nitrogen band of second positive system, using Boltzmann's plot method. In addition, the relative line intensities of nitrogen (0-0) band of first negative system at 391.4 nm and (0-0) band of second positive system at 337.1 nm were also measured to study the variation of electron energy. It was found that the electron excitation temperature decreased from 4 700 to 3 300 K and the molecule vibrational temperature decreased from 3 200 to 2 900 K with increasing gas pressure from 20 to 60 kPa. Besides, the ratio of I(N2+)/I(N2) also decreased with pressure increasing from 20 to 60 kPa, indicating that the average electron energy decreases with the gas pressure increasing. These results are of great importance to the study of plasma dynamics of dielectric barrier discharge and also to the underlying industrial applications. PMID:18422111

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

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

    PubMed

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

    2012-02-01

    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

  9. Investigations Of A New Microwave Plasma Source Operating With Air, N2, CO2, And Argon Gases

    NASA Astrophysics Data System (ADS)

    Le Quang, D.; Babou, Y.; Andre, Pascal

    2011-05-01

    The present contribution will report on the development of a new Microwave Plasma Torch (MPT) at the von Karman institute and on the characterization of subsonic plasma flow of various plasmagene gases (air, N2, CO2 and Ar) at atmospheric pressure. The aim of this work is to explore plasma flow regimes for a large envelope of operating conditions. Using a conventionnal arrangment for MPT, including cylindrical open-ended dielectric quartz tube, plasma generated with molecular gases have been found to be homogeneous plasma while with Argon filamentary structures have been observed. Electrical characterization of the source has been performed for some operating conditions using forwarded and reflected microwave power monitoring. Comprehensive characterization of the flow by means of high speed imaging has been performed to estimate the effect of the oscillation of the delivered power on plasma jet unsteadiness. Analysis in time and frequency domains of the light intensity recorded at 1 kHz rate are presented. Low resolution Optical Emission Spectroscopy (OES) diagnostic was performed in order to identify typical radiative signature of air, N2 and CO2 plasma jet. High resolution OES was performed on pure N2 plasma suitable for thermodynamic characterization using N+2 First Negative and N2 2nd Positive systems. Using thermal equilibrium and chemical nonequilibrium assumption, comparisons between measured and calculated radiative signature of molecular systems evidence for the achievment of thermal equilibrium as well as a slight departure to Saha equilibrium.

  10. 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)

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

    2012-01-01

    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.

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

    SciTech Connect

    Tholeti, Siva Sashank; Alexeenko, Alina A.; Shneider, Mikhail N.

    2014-06-15

    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.

  12. Convergence of Chapman-Enskog calculation of transport coefficients of magnetized argon plasma

    SciTech Connect

    Bruno, D.; Catalfamo, C.; Laricchiuta, A.; Giordano, D.; Capitelli, M.

    2006-07-15

    Convergence properties of the Chapman-Enskog method in the presence of a magnetic field for the calculation of the transport properties of nonequilibrium partially ionized argon have been studied emphasizing the role of the different collision integrals. In particular, the Ramsauer minimum of electron-argon cross sections affects the convergence of the Chapman-Enskog method at low temperature, while Coulomb collisions affect the results at higher temperatures. The presence of an applied magnetic field mitigates the slow convergence for the components affected by the field.

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

    NASA Astrophysics Data System (ADS)

    Wiebold, Matthew D.

    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.

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

    PubMed

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

    2009-01-01

    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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

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

    2010-01-01

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

  17. Towards the reduction of matrix effects in inductively coupled plasma mass spectrometry without compromising detection limits: The use of argon-nitrogen mixed-gas plasma

    NASA Astrophysics Data System (ADS)

    Agatemor, Christian; Beauchemin, Diane

    2011-01-01

    The multivariate optimization of a mixed-gas plasma was conducted in an attempt to find conditions minimizing matrix effects without sacrificing the detection limits that are observed with an all argon plasma optimized for maximum sensitivity in inductively coupled plasma mass spectrometry. Compared to the latter, where 49.1 7.1% (n = 17) analyte signal suppression resulted in the presence of 0.1 M Na, 3.8 3.2% suppression (and 2.8 2.1% enhancement in some cases) was observed in the optimized mixed-gas plasma with 0.13% v/v N 2 in the plasma gas and 0.11% in the central channel as a sheath gas around the nebulizer gas flow. Furthermore, improved detection limits were observed for Al, Co, Pd, and V with the optimized mixed-gas plasma compared to an argon plasma at maximum sensitivity. The robustness of this mixed-gas plasma was further demonstrated through the accurate determination of U and Mo in NASS-5 seawater certified reference material using a simple external calibration, without matrix-matching or internal standardization. Indeed, the result obtained for Mo (9.1 1.9 ?g/L) was within the 95% confidence interval of the certified value of 9.6 1.0 ?g/L, while that obtained for U (3.0 0.2 ?g/L) was close to the information value of 2.6 ?g/L. Spatial profiling results suggest better energy transfer between the toroidal zone and the central channel in the mixed-gas plasma.

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

    PubMed

    Gerhard, Christoph; Roux, Sophie; Brckner, Stephan; Wieneke, Stephan; Vil, Wolfgang

    2012-06-10

    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

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

    USGS Publications Warehouse

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

    1978-01-01

    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.

  20. Sensitivity improvement in laser ablation inductively coupled plasma mass spectrometry achieved using a methane/argon and methanol/water/argon mixed gas plasma.

    PubMed

    Fliegel, Daniel; Frei, Christian; Fontaine, Gisela; Hu, Zhaochu; Gao, Shan; Gnther, Detlef

    2011-12-01

    The influence of the addition of carbon using methane or methanol/water to an inductively coupled plasma (ICP) via the carrier gas flow on the sensitivity in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was studied. During the ablation of SRM NIST 610 with simultaneous addition of CH(4) (0.6-1.4 ml min(-1)), a sensitivity enhancement of more than one order of magnitude for selected analytes (e.g. (75)As(+)) was observed. In addition to the sensitivity enhancement for As, Te, I and Se, also all other measured elements showed a significantly enhanced sensitivity (minimum by a factor of 2). Potential mechanisms for the observed intensity enhancement include charge transfer reactions, a change in the ICP shape and a temperature increase in the plasma. Furthermore, the aspiration of a methanol-water mixture into a cooled spray chamber and the simultaneous addition to the laser ablated aerosol was investigated. This type of mixing leads to a sensitivity enhancement up to a factor of 20. To prevent clogging of the sampler cone and skimmer cone by carbon deposition, a fast cleaning procedure for the interface is tested during running ICP, which allows the application of such a set-up for specific applications. PMID:21881665

  1. Neutralisation of the anti-coagulant effects of heparin by histones in blood plasma and purified systems.

    PubMed

    Longstaff, Colin; Hogwood, John; Gray, Elaine; Komorowicz, Erzsebet; Varj, Imre; Varga, Zoltn; Kolev, Krasimir

    2016-02-29

    Neutrophil extracellular traps (NETs) composed primarily of DNA and histones are a link between infection, inflammation and coagulation. NETs promote coagulation and approaches to destabilise NETs have been explored to reduce thrombosis and treat sepsis. Heparinoids bind histones and we report quantitative studies in plasma and purified systems to better understand physiological consequences. Unfractionated heparin (UFH) was investigated by activated partial thromboplastin time (APTT) and alongside low-molecular-weight heparins (LMWH) in purified systems with thrombin or factor Xa (FXa) and antithrombin (AT) to measure the sensitivity of UFH or LMWH to histones. A method was developed to assess the effectiveness of DNA and non-anticoagulant heparinoids as anti-histones. Histones effectively neutralised UFH, the IC50 value for neutralisation of 0.2 IU/ml UFH was 1.8 g/ml histones in APTT and 4.6 g/ml against 0.6 IU/ml UFH in a purified system. Histones also inhibited the activities of LMWHs with thrombin (IC50 6.1 and 11.0 g/ml histones, for different LMWHs) or FXa (IC50 7.8 and 7.0 g/ml histones). Direct interactions of UFH and LMWH with DNA and histones were explored by surface plasmon resonance, while rheology studies showed complex effects of histones, UFH and LMWH on clot resilience. A conclusion from these studies is that anticoagulation by UFH and LMWH will be compromised by high affinity binding to circulating histones even in the presence of DNA. A complete understanding of the effects of histones, DNA and heparins on the haemostatic system must include an appreciation of direct effects on fibrin and clot structure. PMID:26632486

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

    PubMed

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

    2014-06-10

    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

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

    PubMed Central

    Birnbaum, Jrgen; Hein, Ortrud Vargas; Lhrs, Carsten; Rckbeil, Oskar; Spies, Claudia; Ziemer, Sabine; Grndling, Matthias; Usichenko, Taras; Meissner, Konrad; Pavlovic, Dragan; Kox, Wolfgang J; Lehmann, Christian

    2006-01-01

    Introduction The objective of this study was to determine the effects of the administration of the coagulation factor XIII (F XIII) on intestinal functional capillary density, leukocyte adherence and mesenteric plasma extravasation during experimental endotoxemia. Methods In a prospective, randomized, controlled animal study 42 male Wistar rats were divided into three groups. Group 1 served as the control group. Groups 2 (lipopolysaccharide (LPS) group) and 3 (F XIII group) received endotoxin infusions (2.5 mg/kg/h for 2 hours). In group 3, 50 U/kg body weight F XIII was continuously administered during the first 30 minutes of endotoxemia. F XIII levels were measured in all animals. One half of the animals of each group were studied for intestinal functional capillary density (FCD) and leukocyte adherence on venular endothelium by intravital fluorescence microscopy (IVM). In the other half of each group, mesenteric plasma extravasation (FITC-albumin) was determined by IVM. Results The F XIII level was significantly increased in the F XIII treatment group. In the LPS group, endotoxemia led to a significant reduction of mucosal FCD (-18.5%; p < 0.01 versus control group). F XIII administration in the F XIII group attenuated the decrease in mucosal FCD (-3.7% compared to control; p < 0.05 versus LPS group). During endotoxemia, a significant increase of leukocyte adherence at the endothelium could be noted in the LPS group compared to the control group. Leukocyte adherence at the endothelium and plasma extravasation in the F XIII group did not differ significantly from the LPS group. Conclusion Factor XIII protected mucosal capillary perfusion against endotoxin-induced impairment in an experimental sepsis model in rats, whereas leukocyte adherence and plasma extravasation remained unchanged. PMID:16507148

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

    PubMed

    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

    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

  5. Contribution of a portable air plasma torch to rapid blood coagulation as a method of preventing bleeding

    NASA Astrophysics Data System (ADS)

    Kuo, S. P.; Tarasenko, O.; Chang, J.; Popovic, S.; Chen, C. Y.; Fan, H. W.; Scott, A.; Lahiani, M.; Alusta, P.; Drake, J. D.; Nikolic, M.

    2009-11-01

    The effectiveness and mechanism of a low temperature air plasma torch in clotting blood are explored. Both blood droplets and smeared blood samples were used in the tests. The treated droplet samples reveal how blood clotting depends on the distance at which the torch operated, and for how long the droplets have been exposed to the torch. Microscopy and cell count of smeared blood samples shed light on dependencies of erythrocyte and platelet counts on torch distance and exposure time. With an increase of torch distance, the platelet count of treated blood samples increases but is less than that of the control. The flux of reactive atomic oxygen (RAO) and the degree of blood clotting decreased. With an increase of exposure time, platelet count of treated samples decreased, while the degree of clot increased. The correlation among these dependencies and published data support a blood clotting mechanism that RAO as well as other likely reactive oxygen species generated by the plasma torch activate erythrocyte-platelets interactions and induces blood coagulation.

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

    PubMed

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

    2014-12-01

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

  7. Direct solid atomic emission spectrometric analysis of metal samples by an argon microwave plasma torch coupled to spark ablation

    NASA Astrophysics Data System (ADS)

    Engel, U.; Kehden, A.; Voges, E.; Broekaert, J. A. C.

    1999-09-01

    Spark ablation has been combined to microwave plasma torch atomic emission spectrometry for the direct analysis of compact metallic samples. The material is ablated by a medium voltage spark (450 V, 370 Hz) in a point-to-plane configuration and swept into a 100-W, 2.45-GHz argon microwave discharge. The microwave plasma is observed end-on and the radiation analysed with a polychromator. The detection limits for Fe, Ni, Pb and Sn in brass, Cr, Cu, Ni, Mn, Mo, Si and V in steel and Cu, Fe, Mg, Mn, Si and Zn in aluminium with the microwave plasma torch in the case of measurements with a polychromator are in the μg/g range and by a factor of up to 20 higher than those obtained with spark ablation coupled to inductively coupled plasma atomic emission spectrometry using a high resolution sequential spectrometer. The stability of the emission signal depends on the element studied and relative standard deviations usually are between 0.5 and 3.5%. In the case of low-alloy steels, the linearity and the precision of the calibration could be improved by internal standardisation. Several elements (Cr, Cu, Ni, Si and V) could be determined in a steel sample (BAS SS 410/1) with high accuracy and precision.

  8. Temporally resolved ozone distribution of a time modulated RF atmospheric pressure argon plasma jet: flow, chemical reaction, and transient vortex

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Sobota, A.; van Veldhuizen, E. M.; Bruggeman, P. J.

    2015-08-01

    The ozone density distribution in the effluent of a time modulated RF atmospheric pressure plasma jet (APPJ) is investigated by time and spatially resolved by UV absorption spectroscopy. The plasma jet is operated with an averaged dissipated power of 6.5?W and gas flow rate 2 slm argon??+2% O2. The modulation frequency of the RF power is 50 Hz with a duty cycle of 50%. To investigate the production and destruction mechanism of ozone in the plasma effluent, the atomic oxygen and gas temperature is also obtained by TALIF and Rayleigh scattering, respectively. A temporal increase in ozone density is observed close to the quartz tube exit when the plasma is switched off due to the decrease in O density and gas temperature. Ozone absorption at different axial positions indicates that the ozone distribution is dominated by the convection induced by the gas flow and allows estimating the on-axis local gas velocity in the jet effluent. Transient vortex structures occurring during the switch on and off of the RF power also significantly affect the ozone density in the far effluent.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    In this work, we have studied the performance of different plasma gases (Ar, N2, and O2) and the factors responsible for the improvement of binding of PPy with both polyester thin film and fabric. The plasma was generated by a radio frequency (RF) generator. The gas pressure (8 10-2mbar) and the RF power (100 W) were kept the same, while treatment time varied between 60 and 180 sec. Treated samples were subsequently coated with PPy. The oxygen plasma treated samples showed much more pronounced changes in the surface topography compared to nitrogen and argon plasma treated samples. The contact angle decreased from 84 for the untreated sample to 55 for Argon, 42 for nitrogen and 35 for oxygen plasma-treated samples after 120 sec treatment. Abrasion resistance and conductivity measurements suggest effectiveness of different plasma gases in the following order: O2 > Ar >N2. XPS results show a decrease in C-C (284.6 eV) and an increase in C-O (286.4 eV) and O-C=O (288.7 eV) percentages for each plasma gas, while oxygen to carbon ratios for oxygen, argon and nitrogen plasma are 0.56, 0.5 and 0.46 respectively. It is concluded that improvement of binding of PPy is both due to increased surface roughness and incorporation of oxygen containing functional groups.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    In this work, we have studied the performance of different plasma gases (Ar, N2, and O2) and the factors responsible for the improvement of binding of PPy with both polyester thin film and fabric. The plasma was generated by a radio frequency (RF) generator. The gas pressure (8 10-2 mbar) and the RF power (100 W) were kept the same, while treatment time varied between 60 and 180 sec. Treated samples were subsequently coated with PPy. The oxygen plasma treated samples showed much more pronounced changes in the surface topography compared to nitrogen and argon plasma treated samples. The contact angle decreased from 84 for the untreated sample to 55 for Argon, 42 for nitrogen and 35 for oxygen plasma-treated samples after 120 sec treatment. Abrasion resistance and conductivity measurements suggest effectiveness of different plasma gases in the following order: O2 > Ar > N2. XPS results show a decrease in C-C (284.6 eV) and an increase in C-O (286.4 eV) and O-C=O (288.7 eV) percentages for each plasma gas, while oxygen to carbon ratios for oxygen, argon and nitrogen plasma are 0.56, 0.5 and 0.46 respectively. It is concluded that improvement of binding of PPy is both due to increased surface roughness and incorporation of oxygen containing functional groups.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

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

    2006-06-30

    The emission properties of a volume nanosecond discharge plasma produced in xenon, krypton and argon at high pressures in a discharge gap with a cathode having a small radius of curvature are studied. Spectra in the range 120-850 nm and amplitude-time characteristics of xenon emission at different regimes and excitation techniques are recorded and analysed. It is shown that upon excitation of the volume discharge initiated by a beam of avalanche electrons, at least 90% of the energy in the spectral range 120-850 nm is emitted by xenon dimers. For xenon at a pressure of 1.2 atm, {approx}45 mJ of the spontaneous emission energy was obtained in the full solid angle in a pulse with the full width at half-maximum {approx}130 ns. (laser applications and other topics in quantum electronics)

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

    SciTech Connect

    Umair Siddiqui, M. Hershkowitz, Noah

    2014-02-15

    A hot (T{sub e} ≈ 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.

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

    USGS Publications Warehouse

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

    1982-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Jude, F.; Wattieaux, G.; Merbahi, N.; Mansour, M.; Castani-Cornet, M. P.

    2014-10-01

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

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

    SciTech Connect

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

    1982-07-01

    Inductively coupled argon plasma/optical emission spectrometry (ICAP/OES) is useful as a simultaneous, multielement analytical technique for the determination of trace elements in geological materials. A method for the determination of trace-level rare earth elements (REE) in geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved 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 spills of BCR-1 and BHVO-1. Analyses of other geological materials including coals, soils, and rocks show comparable precision and accuracy.

  17. Comparison between helium and argon plasma jets on improving the hydrophilic property of PMMA surface

    NASA Astrophysics Data System (ADS)

    Wang, Ruixue; Shen, Yuan; Zhang, Cheng; Yan, Ping; Shao, Tao

    2016-03-01

    In this paper, a plasma jet driven by an in-house developed microsecond pulse is used for polymethyl methacrylate (PMMA) surface modification. The hydrophilic modification effects of He and Ar plasma jets are compared under the same condition. The He and Ar plasma jets are characterized by optical emission spectrometer (OES). Water contact angle (WCA) measurement is used to evaluate the wettability of PMMA samples. The evolution on morphology and chemical composition of PMMA before and after plasma treatment are also analyzed. The OES results demonstrate that He plasma is composed with higher intensities of reactive species, like OH, O, N2 and N2+ than that of Ar plasma and show a better modification effect. In addition, it is observed that the surface roughness and oxygen-containing groups like Csbnd O/Csbnd OH and Odbnd Csbnd O increase on the PMMA surface after plasma treatment, which are responsible for the hydrophilic modification. During the storage, the WCA of each sample increases gradually for both He and Ar plasma treatments. The He plasma treated PMMA also shows a slower aging effect than that of Ar plasma treated PMMA.

  18. Temporal variations in the excitation temperature of a laser-induced argon plasma estimated with copper emission lines.

    PubMed

    Sasaki, Yo; Wagatsuma, Kazuaki

    2009-04-01

    A time-resolved spectrometric measurement was conducted to determine temporal variations in the excitation temperature within a single laser plume caused by a Nd:YAG laser plasma. The two-line method using copper atomic lines was employed to estimate the excitation temperature. Two line pairs of copper lines: Cu I 521.82/Cu I 510.55 and Cu I 515.32/Cu I 510.55, were measured by using an Echelle spectrograph equipped with an ICCD detector having a high-speed gating. The excitation temperature was gradually elevated with the progress of the plasma expansion. This result cannot be explained from a direct excitation model in which excited species are principally produced through collisions with energetic particles, but from an indirect excitation model in which second-kind collisions with argon metastables and subsequent step-wise de-excitations produce the excited species. In the latter case, high-lying states of copper atoms are more populated compared to the population expected from the Boltzmann distribution. Temporal variations in the emission intensities of copper atomic lines requiring large excitation energies were also measured, and their emissions remained even in the expansion stage of the laser-induced plasma. This result also implies the over-population of high-lying copper excited levels. PMID:19359786

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

    NASA Astrophysics Data System (ADS)

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

    1998-10-01

    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.

  20. Workfunction tuning of zinc oxide films by argon sputtering and oxygen plasma: an experimental and computational study

    NASA Astrophysics Data System (ADS)

    Kuo, Fang-Ling; Li, Yun; Solomon, Marvin; Du, Jincheng; Shepherd, Nigel D.

    2012-02-01

    Zinc oxide (ZnO) films were grown by radio frequency magnetron sputter deposition and the changes to its surface composition and workfunction induced by argon sputter cleaning and oxygen plasma treatments were characterized using x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and density functional theory modelling. Compared with a workfunction of 3.74 eV for the as-deposited ZnO films, a workfunction of 3.95 eV was obtained after Ar sputter cleaning and 4.21 eV after exposure to oxygen plasma. The data indicate that oxygen plasma treatment leads to a more negative ZnO surface. The dipole induced by this charge redistribution reinforces the original surface dipole, which results in an increase in the surface dipole moment and an increase in workfunction. The reverse is true for hydrocarbon contamination of ZnO surfaces. Excellent qualitative agreement between the experimental results and computational modelling was obtained. The results suggest that specific surface functionalization may be a viable method of controlling the workfunction of ZnO for use as the transparent conducting oxide in optoelectronic applications such as solar cells and organic light-emitting diodes.

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

    SciTech Connect

    Gessel, Bram van; Bruggeman, Peter; Brandenburg, Ronny; Leibniz Institute for Plasma Science and Technology , Felix-Hausdorff-Str. 2, D-17489 Greifswald

    2013-08-05

    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.

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

    NASA Astrophysics Data System (ADS)

    Hlbočan, Peter; Varchola, Michal; Knížat, Branislav; Mlkvik, Marek; Olšiak, Róbert

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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

    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 12cm diameter nozzle with and without a central gas jet on axis. Typical peak drive currents and implosion times in these experiments were 6MA and 230ns. 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 (25MA peak drive currents, 100ns 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 12cm diameter central-jet nozzle configuration, it predicts over 1MJ of K-shell emission is attainable.

  4. On-line nonmetal detection for argon supercritical fluid extraction using inductively coupled plasma optical emission spectroscopy.

    PubMed

    Liang, S; Tilotta, D C

    1998-11-01

    This paper describes the development of a solventless instrumental method for determining organic contaminants in soil by coupling argon supercritical fluid extraction (SFE) to inductively coupled plasma atomic emission spectroscopy (ICP-AES). In this method, organic compounds are first extracted by Ar SFE, transferred to the ICP directly in the supercritical (SC) argon, fragmented in the plasma, and then determined via their nonmetal atomic emissions. Supercritical Ar is superior to SC CO(2) for use in ICP-AES because it overcomes the disadvantages of plasma blowout, noisy baselines, and CO(2) interference in the determination of carbon. All instruments employed were commercially available, and the interface between the SFE and the torch of the ICP consisted of a simple glass capillary tube. Four nonmetals, C, S, P, and Si, were selected for this preliminary study. The selectivities obtained for these nonmetals, referenced to carbon, were found to be 345, 38?000, and 1400 for sulfur, phosphorus, and silicon, respectively. With the exception of carbon, the mass detection limits are in the range of 0.06-1.8 ?g. For this work, the mass detection limit of carbon is 66 ?g and is limited by the smallest aliquot of material that can be injected by syringe. Finally, total petroleum hydrocarbons (TPHs) were determined in two "real world" contaminated soil samples via the carbon emission at 247.9 nm. Dodecane was used as the standard reference compound because its response was found to be similar to other petroleum hydrocarbons (e.g., kerosene, gasoline, no. 1 fuel oil, and no. 2 fuel oil). Additionally, it was found necessary to add a small amount (i.e., 250 mg) of drying agent to the SFE vessel in order to prevent the plasma from extinguishing from the extracted water. The results of the on-line Ar SFE/ICP-AES determinations of TPH in the two samples agreed well with those obtained from conventional off-line CO(2) SFE and off-line Ar SFE. PMID:21644693

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

    SciTech Connect

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

    1987-01-01

    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.

  6. Optical emission diagnostics for plasma parameters in pulse-modulated argon capacitively-coupled discharges

    NASA Astrophysics Data System (ADS)

    Wang, Shicong; Boffard, John B.; Lin, Chun C.; Wendt, Amy E.

    2014-10-01

    Pulsing of discharge power in low pressure rf plasmas is a means to improve materials processing outcomes. Plasma-surface interactions depend on the relative fluxes of ions, reactive neutrals and photons, which can be controlled by adjusting pulse frequency and duty cycle, due their effect on plasma properties, particularly the electron energy distribution. We report on an optical emission spectroscopy (OES) based plasma diagnostic to characterize the time evolution of plasma properties within the pulse cycle for two systems: a pulsed capacitively-coupled plasma (CCP), and a pulsed CCP in combination with a continuous-wave (cw) inductively coupled plasma (ICP); Typical conditions: 30 mTorr Ar, 13.56 MHz rf power (400 W peak CCP and 500 W ICP) and 1 kHz pulse frequency. We quantify the trade off between time resolution versus uncertainty in measured OES intensities. Because only a small fraction of CCP rf power contributes to electron heating, the method is limited by relatively low absolute OES intensities for the CCP-only case, and small incremental changes in intensity when the pulsed CCP is combined with the cw ICP. Nevertheless, with sufficient signal averaging, even subtle changes in parameters induced by the CCP in the latter case can be quantified. This work was supported in part by NSF Grant PHY-1068670.

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

    SciTech Connect

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

    2012-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2014-01-01

    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

  10. Numerical simulation study on fluid dynamics of plasma window using argon

    SciTech Connect

    Huang, S.; Zhu, K.; Shi, B. L.; Lu, Y. R.; Hershcovitch, A.; Yang, L.; Zhang, X. Y.; Wei, G. D.

    2013-07-15

    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.

  11. Comparative study on contribution of charge-transfer collision to excitations of iron ion between argon radio-frequency inductively-coupled plasma and nitrogen microwave induced plasma

    NASA Astrophysics Data System (ADS)

    Satoh, Kozue; Wagatsuma, Kazuaki

    2015-06-01

    This paper describes an ionization/excitation phenomenon of singly-ionized iron occurring in an Okamoto-cavity microwave induced plasma (MIP) as well as an argon radio-frequency inductively-coupled plasma (ICP), by comparing the Boltzmann distribution among iron ionic lines (Fe II) having a wide range of the excitation energy from 4.76 to 9.01 eV. It indicated in both the plasmas that plots of Fe II lines having lower excitation energies (4.76 to 5.88 eV) were fitted on each linear relationship, implying that their excitations were caused by a dominant thermal process such as collision with energetic electron. However, Fe II lines having higher excitation energies (more than 7.55 eV) had a different behavior from each other. In the ICP, Boltzmann plots of Fe II lines assigned to the higher excited levels also followed the normal Boltzmann relationship among the low-lying excited levels, even including a deviation from it in particular excited levels having an excitation energy of ca. 7.8 eV. This deviation can be attributed to a charge-transfer collision with argon ion, which results in the overpopulation of these excited levels, but the contribution is small. On the other hand, the distribution of the high-lying excited levels was non-thermal in the Okamoto-cavity MIP, which did not follow the normal Boltzmann relationship among the low-lying excited levels. A probable reason for the non-thermal characteristics in the MIP is that a charge-transfer collision with nitrogen molecule ion having many vibrational/rotational levels could work for populating the 3d64p (3d54s4p) excited levels of iron ion broadly over an energy range of 7.6-9.0 eV, while collisional excitation by energetic electron would occur insufficiently to excite these high-energy levels.

  12. Effects of argon plasma treatment on the interfacial adhesion of PBO fiber/bismaleimide composite and aging behaviors

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Chen, Ping; Chen, Mingxin; Yu, Qi; Lu, Chun

    2011-09-01

    This paper is concerned with the influence of argon plasma on the interfacial adhesion of PBO fiber/bismaleimide composites and aging behaviors. The interlaminar shear strength (ILSS) was greatly increased to 62.3 MPa with an increase of 39.7% after treatment for 7 min at 80 Pa, 200 W. A small amount of O and N atoms was incorporated onto the fiber surface, but the plasma caused C-O bonds to break and generated Odbnd C-N groups. The fiber surface roughness increased, contributing much to the wettability. However, long-time treatment excessively destroyed the inherent and newly created structures. The SEM images suggested that the fracture shifted from the interface to the matrix. The modification effects degraded with storage time in the air and the ILSS decreased to approximately 54.0 MPa after 10-30 days. The composite had low water absorption of 2.0 wt% and a high retention of 90% in the ILSS at moisture conditions.

  13. Moderate-power argon microwave-induced plasma for the detection of metal ions in aqueous samples of complex matrix

    SciTech Connect

    Brown, P.G.; Haas, D.L.; Workman, J.M.; Caruso, J.A.; Fricke, F.L.

    1987-05-15

    Recent developments have shown microwave-induced plasma optical emission spectrometry (MIP-OES) to be compatible with direct solution introduction of aqueous samples. The present study was performed to further determine the effects of a complex sample matrix on the instrumental response of the moderate-power argon MIP. This was accomplished by examining the emission intensities of several metal ions, ranging in concentration from 10 ppb to 100 ppm, both in 2% HNO/sub 3/ solution and in synthetic ocean water (S.W.). To illustrate matrix effects, the sensitivity and linear dynamic range of each metal in 2% HNO/sub 3/ were compared with the same parameters in synthetic ocean water. Furthermore, to illustrate the application of this method to the analysis of real samples, NBS SRM bovine liver tissues were analyzed by moderate-power Ar MIP and by inductively coupled plasma (ICP) for comparison. It is shown here that the linear dynamic ranges obtained for many metals in complex solution matrices span 2 to 4 or more orders of magnitude and that the detection limits obtained with the MIP compare well with those of the more popular ICP. It is also shown that a complex sample matrix an lead to significant changes in sensitivity (enhancement and suppression). Finally, it is shown that both the MIP and the ICP performed well and were in agreement when used to analyze the NBS SRMs.

  14. Models of blood coagulation.

    PubMed

    Butenas, S; van 't Veer, C; Cawthern, K; Brummel, K E; Mann, K G

    2000-04-01

    We have used three models to study the process of tissue factor-initiated blood coagulation. These are: synthetic 'plasma' mixtures prepared with the proteins and membranes involved in the reaction and its regulation; mathematical models based on the reaction kinetics, binding constants and stoichiometries of individual procoagulant and inhibitor reactions, and contact pathway-inhibited coagulation of minimally altered whole blood in vitro. In all of these models, the procoagulant process may be divided into two phases: an initiation phase and a propagation phase. The initiation phase is characterized by the appearance of thrombin and other coagulation enzymes, and the activation of pro-cofactors V and VIII. The propagation phase is characterized by explosive and extensive prothrombin activation. During normal blood coagulation, the bulk of thrombin generation occurs after clot formation, while most release of fibrinopeptide A is observed just at the conclusion of the initiation phase. In the case of haemophilia A and B, the initiation phase is slightly extended, while thrombin generation during the propagation phase is significantly suppressed. The clot time, as well as fibrinopeptide release, is delayed in these patients. Data obtained in our laboratory, employing the above models, indicate that they are efficient tools for blood coagulation studies. PMID:10850557

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

    SciTech Connect

    Li Guo; Le Peisi; Li Heping; Bao Chengyu

    2010-05-15

    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.

  16. Deuterium occupation of vacancy-type defects in argon-damaged tungsten exposed to high flux and low energy deuterium plasma

    NASA Astrophysics Data System (ADS)

    Zhu, Xiu-Li; Zhang, Ying; Cheng, Long; Yuan, Yue; De Temmerman, Gregory; Wang, Bao-Yi; Cao, Xing-Zhong; Lu, Guang-Hong

    2016-03-01

    Doppler broadening spectroscopy in the positron annihilation technique (DBS-PA) has been employed to investigate the defect properties in argon-damaged tungsten exposed to low-energy and high flux deuterium plasma. Argon ion irradiations with energy 500 keV are performed for tungsten samples with various levels of damage. The remarkable increment of the S parameter in DBS-PA indicates the introduction of vacancy-type defects in argon irradiated tungsten. An increase of ion fluence results in a continuous increase of the S parameter until saturation. Unexpectedly, a much higher fluence leads to a decrease of the S parameter in the near surface, and the (S,W) slope changes greatly. This should be associated with the formation of argon-vacancy complexes in the near surface produced by the excessive implanted argon ions. With deuterium plasma exposure, a significant decrease of the S parameter occurs in the pre-irradiated tungsten, suggesting the sharp reduction of the number and density of the vacancy-type defects. The thermal desorption spectroscopy results demonstrate that the argon-damaged tungsten, compared to the pristine one, exhibits an enhanced low-temperature desorption peak and an additional and broad high-temperature desorption peak, which indicates that deuterium atoms are trapped in both low-energy and high-energy sites. All these observations directly indicate the deuterium occupation of irradiation-induced vacancy defects in damaged tungsten, which is responsible for the remarkable increase of the deuterium retention in comparison with the pristine one.

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

    PubMed

    Lpez-Lozano, Jorge Luis; de Sousa, Marcelo Valle; Ricart, Carlos Andr O; Chvez-Olortegui, Carlos; Flores Sanchez, Eladio; Muniz, Emiro G; Bhrnheim, Paulo F; Morhy, Lauro

    2002-07-01

    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

  18. Argon/Hexamethyldisiloxane Plasma Effects on Poly Propylene Film Surface Properties

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  19. Attenuation of wall disturbances in an electron cyclotron resonance oxygenargon plasma using real time control

    SciTech Connect

    Keville, Bernard Gaman, Cezar; Turner, Miles M.; Zhang, Yang; Daniels, Stephen; Holohan, Anthony M.

    2014-07-01

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

  20. 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)

    Mat?j?ek, J.; Kavka, T.; Bertolissi, G.; Ctibor, P.; Vilmov, M.; Mulek, R.; Nevrl, B.

    2013-06-01

    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.

  1. 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)

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

    2011-12-01

    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 μF, 15 kV (2.8 kJ) capacitor bank consisting of two capacitors each with 12.5 μF 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-Kα 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.

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

    SciTech Connect

    Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady Hassanein, Ahmed

    2014-04-15

    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.

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

    NASA Astrophysics Data System (ADS)

    Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady; Hassanein, Ahmed

    2014-04-01

    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.

  4. Expansion dynamics of ultrafast laser produced plasmas in the presence of ambient argon

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    We investigated the expansion dynamics of fs laser ablated brass plasma in Ar at various pressure levels ranging from 10-5 Torr to atmospheric conditions using time-resolved and spectrally resolved two-dimensional imaging. Significant changes in plume morphology were noticed at varying pressure levels which included free expansion, spherical to cylindrical geometry changes, sharpening, and confinement. The temporal evolution of excited Cu and Zn species in the plume were imaged using narrow band-pass interference filters, and their hydrodynamic expansion features were compared. 2D imaging coupled with monochromatic line selection showed velocity differences, uneven distribution, and aspect ratio differences among the plume species. Plume morphological changes were found to be significant at intermediate pressure levels (˜10 Torr) where plasma emissivity was found to be maximum. The expansion features of plume were compared with various models and found to be generally in good agreement.

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

    SciTech Connect

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

    2014-10-07

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

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

    SciTech Connect

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

    2014-03-15

    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 κ-ε model is used to account for turbulence. In this paper, the plasma is assumed to be a fluid following Navier–Stokes equations, respecting local thermodynamic equilibrium, and described by only one temperature. Distributions of the pressure, velocity, temperature, density, and electric potential inside of thus cascaded arc are obtained for an arc current density of 10{sup 6} A/m{sup 2}. The pressure inside the arc varies from 10{sup 5} Pa to 100 Pa. The temperature at the arc axis can reach as high as 13 600 K. The electric potential drops uniformly along the axis with a magnitude of 160 V. In addition, distributions of the sonic velocity and Mach number are shown to describe supersonic behavior of thus cascaded arc, which have a good agreement with the analytical formula.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  8. Physical and analytical characteristics of an atmospheric pressure argon-helium radiofrequency capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Simon, A.; Anghel, S. D.; Papiu, M.; Dinu, O.

    2010-04-01

    A very low power radiofrequency capacitively coupled plasma (13.56 MHz, 5-70 W), was generated in our laboratory on a sharp Kanthal tip without any counter electrode, as an intrinsic part of RLC series resonant circuit. Physical characteristics of this plasma obtained in Ar-He mixture, were studied as function of observation height or gas mixture composition. The excitation temperature of Ar (1500-2100 K), He (3000-3500 K) and H (2500-3200 K), the rotational temperature of the OH band (1300-2900 K), the electron temperature (5500-6500 K) and the electron number density (8 10 13-2 10 14 cm - 3 ) were determined. The evolution of several atomic emission lines or molecular bands was studied in order to investigate the fundamental processes that take place in such plasma. From the point of view of analytical applications it was found that the optimum conditions of excitation (most intense emission lines and lowest detection limits) are met for a 42% He in the gas mixture and an observation height of 1 mm above the electrode. The optimum atomic emission analysis parameters were established for 7 elements (Na, Li, Ca, K, Cd, Zn and Hg) using pneumatically nebulized liquid solutions. It was found that the presence of He in the plasmogenic gas has an enhancing effect on the emission intensities and detection limits.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  10. Metallurgical consideration on the calibration curve for binary alloy samples in low-pressure argon laser-induced plasma spectrometry.

    PubMed

    Sasaki, Yo; Shimada, Haruhiko; Wagatsuma, Kazuaki

    2011-01-01

    The composition dependence of the emission intensities was investigated in Cu-Ni as well as Ni-Zn binary alloy samples when a low-pressure argon laser-induced plasma was employed as the excitation source. The calibration curve in the Cu-Ni alloy system gave a linear relationship, implying that the selective evaporation of Cu or Ni atoms was caused less in those alloys having several chemical compositions. The Cu-Ni binary alloy has a solid solution phase all over the chemical compositions (all-proportional solid solution): Cu and Ni atoms form no intermetallic compounds but can occupy any positions of a face-centered cubic lattice without any particular interaction. This metallurgical structure would enable Cu and Ni atoms to be released from the sample surface individually, which means that the amount of ablation corresponds to the chemical composition of the alloy sample. For a comparison, a Ni-Zn binary alloy system was also investigated to find calibration curves yielding a nonlinear relationship, differing from those of the Cu-Ni alloy. The reason for this is that the Ni-Zn binary alloy has several metallurgical phases comprising different intermetallic compounds which would each vary the evaporation behavior of Zn. It should be paid attention in LIPS that the ablated composition after laser irradiation is sometimes different from the chemical composition, depending on the kinds of samples and their metallurgical structures. PMID:21478624

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

    SciTech Connect

    Pestehe, S. J.; Mohammadnejad, M.

    2015-02-15

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

  12. Velocity distribution function of sputtered gallium atoms during inductively coupled argon plasma treatment of a GaAs surface

    SciTech Connect

    Despiau-Pujo, Emilie; Chabert, Pascal; Ramos, Raphaeel; Cunge, Gilles; Sadeghi, Nader

    2009-03-15

    A GaN laser diode at 403.3 nm is used to measure the velocity distribution function (vdf) of Ga atoms sputtered from a radio-frequency biased GaAs substrate in a low pressure inductively coupled plasma (ICP) argon discharge. To investigate both perpendicular (V{sub z} normal to wafer) and longitudinal (V{sub x} parallel to wafer) velocity components, laser induced fluorescence (LIF) measurements are performed in the z direction and atomic absorption spectroscopy (AAS) in the x direction. The longitudinal vdf of Ga sputtered atoms is very close to a Lorentzian function with V{sub x} comprised between 0 and 7500 m s{sup -1}, while the perpendicular velocities V{sub z} can reach 10 000 m s{sup -1}. Experimental results are compared to molecular dynamics (MD) simulations of Ar{sup +} ion sputtering of GaAs under 200 eV bombardment. MD predictions and experiments are in fairly good agreement, which confirms the existence of products sputtered from the surface with kinetic energies larger than 10 eV. In etching processes dominated by physical bombardment, these energetic atoms could alter passivation layers on sidewalls and be responsible for defects observed in nanodevices. The best fit of the Doppler-broadened LIF and AAS profiles with the vdfs predicted by sputtering theory allows one to estimate the surface binding energy of Ga atoms in GaAs, E{sub b}, to be around 3 eV.

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

    NASA Astrophysics Data System (ADS)

    Zhu, Xi-Ming; Pu, Yi-Kang

    2010-10-01

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

  14. Effect of combined treatment with immunoadsorption and membrane filtration on plasma coagulation-Results of a randomized controlled crossover study.

    PubMed

    Biesenbach, Peter; Eskandary, Farsad; Ay, Cihan; Wiegele, Marion; Derfler, Kurt; Schaden, Eva; Haslacher, Helmuth; Oberbauer, Rainer; Bhmig, Georg A

    2016-02-01

    The combined use of immunoadsorption (IA) and membrane filtration (MF) may markedly enhance removal of IgM and complement component C1q, supporting its use as an element of recipient desensitization in antibody-incompatible transplantation. However, coagulation factor removal may contribute to altered hemostasis, posing a risk of bleeding in the perioperative setting. This secondary endpoint analysis of standard coagulation assays and rotational thromboelastometry (ROTEM) was performed in the context of a randomized controlled crossover study designed to assess the effect of combined IA (GAM-146-peptide) and MF on levels of ABO antigen-specific IgM. Fourteen patients with autoimmune disorders were randomized to a single treatment with IA+MF followed by IA alone, or vice versa. MF was found to markedly enhance fibrinogen depletion (57% vs. 28% median decrease after IA alone, P?coagulation, extrinsically activated ROTEM() analysis revealed a marked reduction in fibrinogen-dependent clot formation upon IA+MF (59% median decrease in FIBTEM mean clot firmness (MCF) as compared to 24% after IA alone, P?coagulation factors contributing to intrinsically activated coagulation. Our study demonstrates substantial effects of combined IA+MF on clot formation, which may be mainly attributable to fibrinogen depletion. We suggest that the use of combined apheresis in the setting of transplant surgery may necessitate a careful monitoring of coagulation. J. Clin. Apheresis 31:29-37, 2016. 2015 Wiley Periodicals, Inc. PMID:25919120

  15. Argon/UF6 plasma experiments: UF6 regeneration and product analysis

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1980-01-01

    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.

  16. Effects of the electrical excitation signal parameters on the geometry of an argon-based non-thermal atmospheric pressure plasma jet.

    PubMed

    Benabbas, Mohamed Tahar; Sahli, Salah; Benhamouda, Abdallah; Rebiai, Saida

    2014-12-01

    A non-thermal atmospheric pressure argon plasma jet for medical applications has been generated using a high-voltage pulse generator and a homemade dielectric barrier discharge (DBD) reactor with a cylindrical configuration. A plasma jet of about 6cm of length has been created in argon gas at atmospheric pressure with an applied peak to peak voltage and a frequency of 10kV and 50kHz, respectively. The length and the shape of the created plasma jet were found to be strongly dependent on the electrode setup and the applied voltage and the signal frequency values. The length of the plasma jet increases when the applied voltage and/or its frequency increase, while the diameter at its end is significantly reduced when the applied signal frequency increases. For an applied voltage of 10kV, the plasma jet diameter decreases from near 5mm for a frequency of 10kHz to less than 1mm at a frequency of 50kHz. This obtained size of the plasma jet diameter is very useful when the medical treatment must be processed in a reduced space. PACS 2008: 52.50.Dg; 52.70.-m; 52.80.-s. PMID:26088991

  17. Effects of the electrical excitation signal parameters on the geometry of an argon-based non-thermal atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Benabbas, Mohamed Tahar; Sahli, Salah; Benhamouda, Abdallah; Rebiai, Saida

    2014-12-01

    A non-thermal atmospheric pressure argon plasma jet for medical applications has been generated using a high-voltage pulse generator and a homemade dielectric barrier discharge (DBD) reactor with a cylindrical configuration. A plasma jet of about 6 cm of length has been created in argon gas at atmospheric pressure with an applied peak to peak voltage and a frequency of 10 kV and 50 kHz, respectively. The length and the shape of the created plasma jet were found to be strongly dependent on the electrode setup and the applied voltage and the signal frequency values. The length of the plasma jet increases when the applied voltage and/or its frequency increase, while the diameter at its end is significantly reduced when the applied signal frequency increases. For an applied voltage of 10 kV, the plasma jet diameter decreases from near 5 mm for a frequency of 10 kHz to less than 1 mm at a frequency of 50 kHz. This obtained size of the plasma jet diameter is very useful when the medical treatment must be processed in a reduced space.

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

    SciTech Connect

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

    1995-08-01

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

  19. A Prospective Randomized Experimental Study to Investigate the Eradication Rate of Endometriosis after Surgical Resection versus Aerosol Plasma Coagulation in a Rat Model

    PubMed Central

    Rothmund, Ralf; Scharpf, Marcus; Tsaousidis, Christos; Planck, Constanze; Enderle, Markus Dominik; Neugebauer, Alexander; Kroeker, Kristin; Nuessle, Daniela; Fend, Falko; Brucker, Sara; Kraemer, Bernhard

    2016-01-01

    Purpose To investigate the eradication rate of endometriosis after surgical resection (SR) vs. thermal ablation with aerosol plasma coagulation (AePC) in a rat model. Methods In this prospective, randomized, controlled, single-blinded animal study endometriosis was induced on the abdominal wall of 34 female Wistar rats. After 14 days endometriosis was either removed by SR or ablated by AePC. 14 days later the rats were euthanized to evaluate the eradication rate histopathologically. Intervention times were recorded. Results Eradication rate of endometriosis after 14 days did not significantly differ between AePC and SR (p=0.22). Intervention time per endometrial lesion was 22.1 s for AePC and 51.8 s for SR (p<0.0001). Conclusions This study compares the eradication rate of the new aerosol plasma coagulation device versus standard surgical resection of endometriosis in a rat model. Despite being a thermal method, AePC showed equality towards SR regarding eradication rate but with significantly shorter intervention time. PMID:26941579

  20. Low energy ion impact-enhanced growth of cubic boron nitride in a supersonic nitrogen/argon plasma flow

    SciTech Connect

    Berns, D.H.; Cappelli, M.A.

    1997-08-01

    This paper describes the growth and analysis of cubic boron nitride films in a low-density, supersonic nitrogen/argon plasma flow into which boron trichloride gas was injected. Both hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN) were synthesized using this apparatus. Phase selectivity is obtained by applying a relatively low negative bias voltage on the substrate. All of the films described in this paper were grown on {l_brace}100{r_brace} silicon wafers at substrate temperatures varying from 400{endash}700{degree}C. Boron nitride films with greater than 90{percent} cubic phase were successfully synthesized with this method. The films were analyzed using infrared spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. The volumetric percentages of the hexagonal and cubic phases were determined from model fits to the infrared transmission spectra of the films. X-ray photoelectron spectroscopy provided qualitative evidence for the presence and/or lack of sp{sup 2} bonding through the identification of a {pi}-plasmon feature in the spectra. Infrared reflectance spectra are used to provide insight into the growth mechanisms leading to c-BN formation and have revealed features which are not present in the transmission spectra, specifically the 1305cm{sup {minus}1} LO mode of c-BN and the 1610cm{sup {minus}1} LO mode of h-BN. The mean ion energies involved with this bias-enhanced chemical vapor deposition (CVD) process are much lower than the ion energies in traditional physical vapor deposition processes; however, the ion fluxes (currents) used in this CVD process are at least an order of magnitude higher, resulting in a total momentum transfer to the deposited atoms through ion bombardment that is at least equal to or greater than that reported for many ion-enhanced PVD processes. {copyright} {ital 1997 Materials Research Society.}

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

    SciTech Connect

    Forati, Ebrahim Piltan, Shiva; Sievenpiper, Dan

    2015-02-02

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

  2. Numerical analysis of nitrogen-mixed argon plasma characteristics and injected particle behavior in an ICP torch for ultrafine powder synthesis

    SciTech Connect

    Park, J.H.; Hong, S.H.

    1995-08-01

    The ICP (inductively coupled plasma) torches have been extensively used for the synthesis of various ceramics and new materials as effective hot-temperature heat sources in the field of material processing. Here, a numerical model is presented for the analysis of plasma characteristics of an ICP torch and gas mixing effects on the plasma when a nitrogen gas is added into the argon plasma as a carrier or sheath gas at the torch inlet. The fluid equations describing the plasma flow and temperature fields and the diffusions between two different gases are solved along with a magnetic vector potential equation for electromagnetic fields. The trajectory and the temperature change with time for a particle injected into the plasma are also investigated by a plasma-particle interaction model to find out optimum injection conditions for the synthesis of ultra/fine nitride ceramic powders. It is found from the calculations that the nitrogen-mixed argon plasma with a nitrogen carrier gas for the reaction kinetics of nitride synthesis. It is also found that the radial injection through the holes of the tube wall is preferable to the axial injection at the torch inlet for the complete evaporation of injected particle and the effective chemical reaction of reactant vapor with nitrogen. For the radial injection in an ICP torch of 20 cm in axial length, the optimum injection locations and initial velocities of 50-{micro}m aluminum particles are found for synthesizing aluminum nitride are in the range of 6{approximately}12 cm apart from the torch inlet and over 15 m/s, respectively.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  4. Argon plasma inductively coupled plasma reactive ion etching study for smooth sidewall thin film lithium niobate waveguide application

    NASA Astrophysics Data System (ADS)

    Ulliac, G.; Calero, V.; Ndao, A.; Baida, F. I.; Bernal, M.-P.

    2016-03-01

    Lithium Niobate (LN) exhibits unique physical properties such as remarkable electro-optical coefficients and it is thus an excellent material for a wide range of fields like optic communications, lasers, nonlinear optical applications, electric field optical sensors etc. In order to further enhance the optical device performance and to be competitive with silicon photonics, sub-micrometric thickness lithium niobate films are crucial. A big step has been achieved with the development of LN thin films by using smart cut technology and wafer bonding and these films are nowadays available in the market. However, it is a challenge to obtain the requirements of the high quality thin LN film waveguide. In this letter, we show smooth ridge waveguides fabricated on 700 nm thickness thin film lithium niobate (TFLN). The fabrication has been done by developing and optimizing three steps of the technological process, the mask fabrication, the plasma etching, and a final cleaning wet etching step in order to remove the lithium niobate redeposition on the side walls. We have obtained single mode propagation with light overall losses of only 5 dB/cm.

  5. First principles transport coefficients and reaction rates of Ar2(+) ions in argon for cold plasma jet modeling.

    PubMed

    Chicheportiche, Alexandre; Stacho?, Martin; Benhenni, Malika; Gada, Florent Xavier; Kalus, Ren; Yousfi, Mohammed

    2014-10-01

    Momentum-transfer collision cross-sections and integral collision cross-sections for the collision-induced dissociation are calculated for collisions of ionized argon dimers with argon atoms using a nonadiabatic semiclassical method with the electronic Hamiltonian calculated on the fly via a diatomics-in-molecules semiempirical model as well as inverse-method modeling based on simple isotropic rigid-core potential. The collision cross-sections are then used in an optimized Monte Carlo code for evaluations of the Ar 2 (+) mobility in argon gas, longitudinal diffusion coefficient, and collision-induced dissociation rates. A thorough comparison of various theoretical calculations as well as with available experimental data on the Ar 2 (+) mobility and collision cross-sections is performed. Good agreement is found between both theoretical approaches and the experiment. Analysis of the role of inelastic processes in Ar 2 (+)/Ar collisions is also provided. PMID:25296801

  6. UPLC-MRM Mass Spectrometry Method for Measurement of the Coagulation Inhibitors Dabigatran and Rivaroxaban in Human Plasma and Its Comparison with Functional Assays

    PubMed Central

    Kuhn, Joachim; Gripp, Tatjana; Flieder, Tobias; Dittrich, Marcus; Hendig, Doris; Busse, Jessica; Knabbe, Cornelius; Birschmann, Ingvild

    2015-01-01

    Introduction The fast, precise, and accurate measurement of the new generation of oral anticoagulants such as dabigatran and rivaroxaban in patients plasma my provide important information in different clinical circumstances such as in the case of suspicion of overdose, when patients switch from existing oral anticoagulant, in patients with hepatic or renal impairment, by concomitant use of interaction drugs, or to assess anticoagulant concentration in patients blood before major surgery. Methods Here, we describe a quick and precise method to measure the coagulation inhibitors dabigatran and rivaroxaban using ultra-performance liquid chromatography electrospray ionization-tandem mass spectrometry in multiple reactions monitoring (MRM) mode (UPLC-MRM MS). Internal standards (ISs) were added to the sample and after protein precipitation; the sample was separated on a reverse phase column. After ionization of the analytes the ions were detected using electrospray ionization-tandem mass spectrometry. Run time was 2.5 minutes per injection. Ion suppression was characterized by means of post-column infusion. Results The calibration curves of dabigatran and rivaroxaban were linear over the working range between 0.8 and 800 ?g/L (r >0.99). Limits of detection (LOD) in the plasma matrix were 0.21 ?g/L for dabigatran and 0.34 ?g/L for rivaroxaban, and lower limits of quantification (LLOQ) in the plasma matrix were 0.46 ?g/L for dabigatran and 0.54 ?g/L for rivaroxaban. The intraassay coefficients of variation (CVs) for dabigatran and rivaroxaban were < 4% and 6%; respectively, the interassay CVs were < 6% for dabigatran and < 9% for rivaroxaban. Inaccuracy was < 5% for both substances. The mean recovery was 104.5% (range 83.8113.0%) for dabigatran and 87.0% (range 73.6105.4%) for rivaroxaban. No significant ion suppressions were detected at the elution times of dabigatran or rivaroxaban. Both coagulation inhibitors were stable in citrate plasma at -20C, 4C and even at RT for at least one week. A method comparison between our UPLC-MRM MS method, the commercially available automated Direct Thrombin Inhibitor assay (DTI assay) for dabigatran measurement from CoaChrom Diagnostica, as well as the automated anti-Xa assay for rivaroxaban measurement from Chromogenix both performed by ACL-TOP showed a high degree of correlation. However, UPLC-MRM MS measurement of dabigatran and rivaroxaban has a much better selectivity than classical functional assays measuring activities of various coagulation factors which are susceptible to interference by other coagulant drugs. Conclusions Overall, we developed and validated a sensitive and specific UPLC-MRM MS assay for the quick and specific measurement of dabigatran and rivaroxaban in human plasma. PMID:26699714

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    Our recently developed collisional-radiative model which included fine-structure cross sections calculated with a fully relativistic distorted-wave method [R.K. Gangwar, L. Sharma, R. Srivastava, A.D. Stauffer, J. Appl. Phys. 111, 053307 (2012)] has been extended to study non-Maxwellian inductively coupled argon plasmas. We have added more processes to our earlier collisional-radiative model by further incorporating relativistic distorted-wave electron impact cross sections from the 3 p 54 sJ = 0, 2 metastable states, (1 s 3, 1 s 5 in Paschen’s notation) to the 3 p 55 p (3 p i ) excited states. The population of various excited levels at different pressures in the range of 1-25 mTorr for an inductively coupled argon plasma have been calculated and compared with the recent optical absorption spectroscopy measurements as well as emission model results of Boffard et al. [Plasma Sources Sci. Technol. 19, 065001 (2010)]. We have also calculated the intensities of two emission lines, 420.1 nm (3 p 9 → 1 s 5) and 419.8 nm (3 p 5 → 1 s 4) and compared with measured intensities reported by Boffard et al. [J. Phys. D 45, 045201 (2012)]. Our results are in good agreement with the measurements.

  8. 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)

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

    2013-10-01

    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.

  9. Systems biology of coagulation.

    PubMed

    Diamond, S L

    2013-06-01

    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

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

    SciTech Connect

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

    2015-01-14

    An tunable diode laser absorption spectroscopy has been used to determine the Ar*({sup 3}P{sub 2}) and Ar*({sup 3}P{sub 0}) metastable atoms densities in dual-frequency capacitively coupled plasmas. The effects of different control parameters, such as high-frequency power, gas pressure and content of Ar, on the densities of two metastable atoms and electron density were discussed in single-frequency and dual-frequency Ar discharges, respectively. Particularly, the effects of the pressure on the axial profile of the electron and Ar metastable state densities were also discussed. Furthermore, a simple rate model was employed and its results were compared with experiments to analyze the main production and loss processes of Ar metastable states. It is found that Ar metastable state is mainly produced by electron impact excitation from the ground state, and decayed by diffusion and collision quenching with electrons and neutral molecules. Besides, the addition of CF{sub 4} was found to significantly increase the metastable destruction rate by the CF{sub 4} quenching, especially for large CF{sub 4} content and high pressure, it becomes the dominant depopulation process.

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

    SciTech Connect

    Ma Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu Jin; Lei Wenqi; Bai Xueshi; Zheng Lijuan; Zeng Heping

    2012-03-01

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

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

    SciTech Connect

    Bai Xueshi; Ma Qianli; Motto-Ros, Vincent; Yu Jin; Sabourdy, David; Nguyen, Luc; Jalocha, Alain

    2013-01-07

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

  13. Hydroxyurea increases plasma concentrations of microparticles and reduces coagulation activation and fibrinolysis in patients with sickle cell anemia.

    PubMed

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

    2015-01-01

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

  14. Continuous Wave Cavity Ring-Down Spectroscopy and Laser Induced Fluorescence Measurements of Argon Ion Velocity Distribution Functions in a Helicon Plasma

    NASA Astrophysics Data System (ADS)

    McCarren, Dustin; Vandervort, Robert; Soderholm, Mark; Scime, Earl

    2014-10-01

    LIF is an established and powerful technique, but suffers from the requirement that the initial state of the LIF sequence have a substantial density. This usually limits LIF to ions and atoms with large metastable state densities for the given plasma conditions. Cavity ring down spectroscopy (CRDS) is a proven, ultra-sensitive, cavity enhanced absorption spectroscopy technique and when combined with a continuous wavelength (CW) diode laser that has a sufficiently narrow line width, the Doppler broadened absorption line, i.e., the target specie velocity distribution function (VDFs), is measured. CW-CRDS is designed for measurements of ion and atom states inaccessible to conventional techniques such as LIF. However, being a line integrated technique, CW-CRDS lacks the spatial resolution of LIF. We present a comparison of CW-CRDS and spatially resolved LIF measurements of the VDFs in an argon plasma using the 668.614 nm (in vacuum) line of Ar II.

  15. Aptamer RA36 inhibits of human, rabbit, and rat plasma coagulation activated with thrombin or snake venom coagulases.

    PubMed

    Savchik, E Yu; Kalinina, T B; Drozd, N N; Makarov, V A; Zav'yalova, E G; Lapsheva, E N; Mudrik, N N; Babij, A V; Pavlova, G V; Golovin, A V; Kopylov, A M

    2013-11-01

    RA36 DNA aptamer is a direct anticoagulant prolonging clotting time of human, rabbit, and rat plasma in the thrombin time test. Anticoagulant activity of RA36 is lower than that of recombinant hirudin. During inhibition of human plasma clotting activated with echitox (coagulase from Echis multisquamatus venom), the aptamer presumably binds to meisothrombin exosite I. The sensitivity of human plasma to the aptamer 5-fold surpasses that of rat plasma. Analysis of RA36 binding to coagulase of Agkistrodon halys venom (ancistron) is required for proving the effect of aptamer on polymerization of human fibrinogen. PMID:24319726

  16. Detection of fast electrons in pulsed argon inductively-coupled plasmas using the 420.1419.8?nm emission line pair

    NASA Astrophysics Data System (ADS)

    Boffard, John B.; Wang, S.; Lin, Chun C.; Wendt, A. E.

    2015-12-01

    Pulsed rf plasmas exhibit many differences as compared to continuous wave plasmas with the same average power levels, including large temporal variations in the electron temperature, with a sharp spike when the power is applied and falling dramatically in the afterglow. We present a comparison of time-resolved measurements of the effective electron temperature in pulsed inductively-coupled plasmas by means of (i) optical emission spectroscopy (OES) using different sets of argon emission lines and (ii) Langmuir probe measurements. One OES diagnostic used six strong Ar(2{{\\text{p}}x}\\to 1{{\\text{s}}y} ) emission lines in the 700800?nm wavelength range, the second used only the Ar 420.1419.8?nm line pair. For pulsed plasmas with long afterglow periods, the line pair method reveals the presence of a significant number of hot electrons (E?slant 22 eV) at the start of the pulse. Under these conditions, the metastable atom density is very low, and the diagnostic using the Ar(2{{\\text{p}}x}\\to 1{{\\text{s}}y} ) emission lines is ineffective for determining the electron temperature. For later parts of the pulse and pulsed plasmas with short periods (i.e. 10 ?s), the metastable density is high and the two OES methods yield similar results which are also in agreement with probe measurements.

  17. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    DOE PAGESBeta

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected tomore » collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.« less

  18. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    PubMed Central

    Franz, Robert; Polcik, Peter; Anders, Andr

    2015-01-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings. PMID:26120236

  19. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    SciTech Connect

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.

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

    NASA Astrophysics Data System (ADS)

    Razzak, M. Abdur; Takamura, Shuichi; Uesugi, Yoshihiko

    2004-11-01

    The influences of rf driving power, neutral gas pressure, and nitrogen seeding on the electrostatic-to-electromagnetic (E-H) mode transition dynamics in radio-frequency argon inductively coupled plasmas (ICPs) in a pressure range of 50-100kPa are investigated, both experimentally and theoretically. The E-H mode transition dynamics and its characteristic transition time scale are investigated by observing the high-speed imaging (13500fps) as well as the temporal change of plasma loading impedance. The experimental results reveal that the E-H mode transition time is not fixed at any operating conditions rather it depends on some important parameters such as the rf driving power, neutral gas pressure, gas type. It is found that the E-H mode transition time depends on the unique parameter Eθ/p; the so-called effective induced electric field, rather than the independent parameter: the rf power or neutral gas pressure. It is also found that longer E-H mode transition time is required to ignite the high-pressure Ar-N2 plasmas with a 2.5%-10% N2 seeding than that of pure Ar plasmas with the same operating conditions. The experimental results are compared with that of the recently developed theoretical models, and a good agreement is found between them.

  1. Enhancement of intensities in glow discharge mass spectrometry by using mixtures of argon and helium as plasma gases.

    PubMed

    Lange, Britta; Matschat, Ralf; Kipphardt, Heinrich

    2007-12-01

    Glow discharge mass spectrometry (GD-MS) is an excellent technique for fast multi-element analysis of pure metals. In addition to metallic impurities, non-metals also can be determined. However, the sensitivity for these elements can be limited due to their high first ionization potentials. Elements with a first ionization potential close to or higher than that of argon, which is commonly used as discharge gas in GD-MS analysis, are ionized with small efficiency only. To improve the sensitivity of GD-MS for such elements, the influence of different glow-discharge parameters on the peak intensity of carbon, chlorine, fluorine, nitrogen, phosphorus, oxygen, and sulfur in pure copper samples was investigated with an Element GD (Thermo Fisher Scientific) GD-MS. Discharge current, discharge gas flow, and discharge gas composition, the last of which turned out to have the greatest effect on the measured intensities, were varied. Argon-helium mixtures were used because of the very high potential of He to ionize other elements, especially in terms of the high energy level of its metastable states. The effect of different Ar-He compositions on the peak intensity of various impurities in pure copper was studied. With Ar-He mixtures, excellent signal enhancements were achieved in comparison with use of pure Ar as discharge gas. In this way, traceable linear calibration curves for phosphorus and sulfur down to the microg kg(-1) range could be established with high sensitivity and very good linearity using pressed powder samples for calibration. This was not possible when pure argon alone was used as discharge gas. PMID:17940753

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

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

    2014-12-15

    The measurements of the ion densities in the atmospheric AC barrier corona argon discharge are carried out by receiving and analyzing the frequencies of the electromagnetic radiation emitted from the plasma. An auxiliary excitation source composed of a pin-to-pin discharge system is introduced to excite the oscillations of the main discharge. To analyze the resonance mechanism, a complemented model based on a one-dimensional description of forced vibrations is given. Calculations indicate that Ar{sub 2}{sup +} is the dominant ion (∼89% in number density). By analyzing resonance frequencies, the ion densities of Ar{sub 2}{sup +} are in the order of 10{sup 19}∼10{sup 20}m{sup −3} and increase slowly as the applied voltage increases.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Influence of low energy argon plasma treatment on the moisture barrier performance of hot wire-CVD grown SiNx multilayers

    NASA Astrophysics Data System (ADS)

    Majee, Subimal; Ftima Cerqueira, Maria; Tondelier, Denis; Geffroy, Bernard; Bonnassieux, Yvan; Alpuim, Pedro; Boure, Jean Eric

    2014-01-01

    The reliability and stability are key issues for the commercial utilization of organic photovoltaic devices based on flexible polymer substrates. To increase the shelf-lifetime of these devices, transparent moisture barriers of silicon nitride (SiNx) films are deposited at low temperature by hot wire CVD (HW-CVD) process. Instead of the conventional route based on organic/inorganic hybrid structures, this work defines a new route consisting in depositing multilayer stacks of SiNx thin films, each single layer being treated by argon plasma. The plasma treatment allows creating smoother surface and surface atom rearrangement. We define a critical thickness of the single layer film and focus our attention on the effect of increasing the number of SiNx single-layers on the barrier properties. A water vapor transmission rate (WVTR) of 2 10-4 g/(m2day) is reported for SiNx multilayer stack and a physical interpretation of the plasma treatment effect is given.

  6. A new flexible DBD device for treating infected wounds: in vitro and ex vivo evaluation and comparison with a RF argon plasma jet

    NASA Astrophysics Data System (ADS)

    Boekema, B. K. H. L.; Vlig, M.; Guijt, D.; Hijnen, K.; Hofmann, S.; Smits, P.; Sobota, A.; van Veldhuizen, E. M.; Bruggeman, P.; Middelkoop, E.

    2016-02-01

    Cold plasma has been shown to provide a promising alternative antimicrobial treatment for wound healing. We developed and tested a flexible surface dielectric barrier discharge (DBD) and compared it to an argon gas based plasma jet operated remotely with a distance between plasma plume and sample of 8 mm. Tests were conducted using different models: on cultured cells, on ex vivo human skin and on bacteria (Pseudomonas aeruginosa) (on agar, in suspension, in collagen/elastin matrix or on ex vivo human skin), allowing us to directly compare bactericidal with safety aspects under identical conditions. Both plasma devices were highly efficient when used on bacteria in non-buffered solutions, but DBD was faster in reaching the maximum bacterial reduction. Treatment of bacteria on intact skin with DBD resulted in up to 6 log reductions in 3 min. The jet was far less efficient on intact skin. Even after 8 min treatment no more than 2 log reductions were obtained with the jet. Treatment of bacteria in burn wound models with DBD for 6 min resulted in a 4.5 log reduction. Even when using DBD for 6 min on infected burn wound models with colonizing or biofilm phase bacteria, the log reductions were 3.8 or 3.2 respectively. DBD plasma treatment for 6 min did not affect fibroblast viability, whereas a treatment for 8 min was detrimental. Similarly, treatment with DBD or plasma jet for 6 min did also not affect the metabolic activity of skin biopsies. After treatment for 8 min with DBD or plasma jet, 78% or 60% of activity in skin biopsies remained, respectively. Multiple treatments of in vitro burn wound models with surface DBD for 6 min or with plasma jet for 8 min did not affect re-epithelialization. With the flexible surface DBD plasma strip we were able to quickly inactivate large numbers of bacteria on and in skin. Under the same conditions, viability of skin cells or re-epithelialization was not affected. The DBD source has potential for treating larger wound areas.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  9. Spectroscopic and analytical characteristics of an inductively coupled argon plasma combined with hydride generation with or without simultaneous introduction of the sample aerosol for optical emission spectrometry.

    PubMed

    Pohl, Pawel; Broekaert, Jose A C

    2010-09-01

    A radially viewed inductively coupled argon plasma was used for optical emission spectrometry of volatile species formed by reaction with NaBH(4) (hydride generation). The volatile hydrides were either introduced into the plasma alone or at the same time as a sample aerosol generated by pneumatic nebulization with a commercially available Concomitant Metals Analyzer. The effects of the forward power, the presence of pre-reducing agents [(NH(2))(2)SC, KI, KBr and hot HCl], the occurrence of easily ionized elements (Ca, K, Mg and Na) in the analyte solutions on the excitation temperature (as measured via Ar atomic lines) and the electron number density were investigated for both of the sample introduction modes applied. The detection limits and the signal-to-background intensity ratios for As, Bi, Sb, Se and Sn lines were also evaluated and were observed to deteriorate with increasing power. When simultaneous hydride generation and pneumatic nebulization was employed under optimized experimental conditions, detection limits of 3.5, 2.9, 4.3, 1.5 and 2.1 microg L(-1) for As, Bi, Sb, Se and Sn, respectively, were obtained, and the intensities of the analytical lines for elements that do not form volatile hydrides were found to be 40% (Cd), 30% (Ni), 20% (Co, Cr, Fe, Mn and Zn) and 10% (Cu, Mg, V) greater than those obtained when only pneumatic nebulization was used. PMID:20582404

  10. Nonmetals in the argon-inductively coupled plasma-optical emission spectrometry: I. Phosphorus, sulfur and carbon.

    PubMed

    Knauthe, B; Otto, M

    2001-12-01

    The behavior of phosphorus, sulfur and carbon in the argon-ICP-OES was systematically investigated for a wide range of nebulizer gas flows and observation heights. Five lines of phosphorus, four lines of sulfur and three lines of carbon, which have analytical usable detection limits, were taken into consideration. The further parameter set was inspired by the needs of every-day-analysis in the laboratory, especially the low integration time that is necessary for analysis of large amounts of samples. For each element line a signal-to-noise plot was obtained with a method described earlier. The optimum conditions for the combined analysis were determined from signal-to-noise plots of those element lines with the lowest detection limits. The lowest detection limits for phosphorus (0.13 mg/L) and carbon (0.01 mg/L) are useful for solving many analytical problems. However, even the best detection limit for sulfur (2.97 mg/L) is only of limited use without further preconcentration. A major problem was the background of carbon, most probably from carbon dioxide, which increased the available detection limit to about 0.04 mg/L. Surprisingly, the best detection limits were obtained at very low observation heights, which were only a couple of millimeters above the load coil. Fortunately, all elements showed a similar behavior and so the detection limits at compromise conditions were only slightly higher compared with the single-element detection limits. PMID:11798096

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

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

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

    SciTech Connect

    Baronova, E. O.; Sholin, G. V.; Vikhrev, V. V.; Jakubowski, L.

    2008-03-19

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

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

    SciTech Connect

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

    1996-10-01

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

  14. Time-resolved measurement of copper emission spectrum excited by a low-pressure argon laser-induced plasma.

    PubMed

    Ushirozawa, Yohei; Wagatsuma, Kazuaki

    2006-07-01

    A laser-induced plasma generated with a pulsed Nd:YAG laser under evacuated conditions has complicated structures both temporally and spatially. The time-resolved spectra of copper in three different wavelength regions were observed in detail for elucidating the excitation mechanisms of many atomic/ionic copper emission lines. The emission intensities of copper emission lines, measured in a time-resolved mode, were strongly dependent on the kind of copper lines: ionic or atomic lines, and their excitation energies. Generally, copper ionic lines were rapidly decayed and dominantly emitted from the initial breakdown zone, because the copper ions requiring larger excitation energies were produced mainly in the hot breakdown zone. On the other hand, the atomic lines were emitted during prolonged periods, implying that they could also be excited in the expanded plasma zone. The excitation phenomena occurring in the laser-induced plasma could be better understood by analyzing the time-resolved copper spectra. PMID:16837755

  15. Bustling argon: biological effect

    PubMed Central

    2013-01-01

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

  16. 2D collisional-radiative model for non-uniform argon plasmas: with or without ‘escape factor’

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  17. Measurement of the total energy lost per electron-ion lost in argon, helium and oxygen inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Ku, Ju-Hwan; Lee, Young-Kwang; Oh, Seung-Ju; Chung, Chin-Wook

    2009-10-01

    The total energy lost per electron-ion pair lost was measured at various gases (Ar, O2, He, Ar/O2, Ar/He) and in the pressure range of 5--50 mTorr in an inductively coupled plasma. A floating harmonics method [1] was used to measure the electron temperatures and ion fluxes at the chamber wall. The absorbed power was determined by measuring the antenna resistance and current. The total energy lost were determined from a power balance equation of a global model. The measured of the total energy lost per electron-ion pair ranged from 80 V to 250 V for Ar and from 70 V to 90 V for He, respectively. In molecular gas, it ranged from 250 V to 2300 V for O2 plasma due to additional collisional energy losses. The measured total energy lost decrease with absorbed power and increase with pressure. In mixture discharges, the total energy lost rapidly increase with mixing ratio of oxygen in Ar/O2 plasma while the total energy lost slightly decrease with mixing ratio of helium in Ar/He plasma. These experimental results were consistent with theoretical ones. [4pt] [1] M. H. Lee, S. H. Jang, C. W. Chung, J. Appl. Phys. 101, 033305 (2007).

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

    SciTech Connect

    Shcheglov, A.N.; Vasilets, V.N.; Ponomarev, A.N.

    1995-09-01

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

  19. Enhanced ozone production in a pulsed dielectric barrier discharge plasma jet with addition of argon to a He-O2 flow gas

    NASA Astrophysics Data System (ADS)

    Sands, Brian; Ganguly, Biswa; Scofield, James

    2013-09-01

    Ozone production in a plasma jet DBD driven with a 20-ns risetime unipolar pulsed voltage can be significantly enhanced using helium as the primary flow gas with an O2 coflow. The overvolted discharge can be sustained with up to a 5% O2 coflow at <20 kHz pulse repetition frequency at 13 kV applied voltage. Ozone production scales with the pulse repetition frequency up to a ``turnover frequency'' that depends on the O2 concentration, total gas flow rate, and applied voltage. For example, peak ozone densities >1016 cm-3 were measured with 3% O2 admixture and <3 W input power at a 12 kHz turnover frequency. A further increase in the repetition frequency results in increased discharge current and 777 nm O(5 P) emission, but decreased ozone production and is followed by a transition to a filamentary discharge mode. The addition of argon at concentrations >=5% reduces the channel conductivity and shifts the turnover frequency to higher frequencies. This results in increased ozone production for a given applied voltage and gas flow rate. Time-resolved Ar(1s5) and He(23S1) metastable densities were acquired along with discharge current and ozone density measurements to gain insight into the mechanisms of optimum ozone production.

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

    SciTech Connect

    Huebner, S.; Carbone, E. A. D.; Mullen, J. J. A. M. van der; Sadeghi, N.

    2013-04-14

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

  1. Dynamics of laser-ablated MgB2 plasma expanding in argon probed by optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Amoruso, Salvatore; Bruzzese, Riccardo; Spinelli, Nicola; Velotta, Raffaele; Vitiello, Marco; Wang, Xuan

    2003-06-01

    We have used time and space-resolved optical emission spectroscopy to study the expansion dynamics of the plasma generated by pulsed laser ablation of solid targets of the recently discovered superconducting MgB2 into a background Ar gas at different pressures. Our analysis clearly indicates that, above a fixed pressure, plasma propagation into Ar leads to both the formation of a shock wave, which causes a considerable increase of the fraction of excited Mg atoms, and the simultaneous reduction of the kinetic flux energy of the ablated atoms. These results have then been analyzed in the framework of a simplified gas dynamic approach for the description of free-plume self-similar expansion and of a point-blast-wave model to account for the interaction of the plume with the Ar ambient gas, thus obtaining full support and a sound physical interpretation of our experimental observations. Finally, we have related our conclusions to the general problem of the optimization of the thin-film deposition of laser-ablated materials, with particular emphasis given to the specific case of MgB2, which is of great, present interest.

  2. EPR-Spin Trapping and Flow Cytometric Studies of Free Radicals Generated Using Cold Atmospheric Argon Plasma and X-Ray Irradiation in Aqueous Solutions and Intracellular Milieu

    PubMed Central

    Uchiyama, Hidefumi; Zhao, Qing-Li; Hassan, Mariame Ali; Andocs, Gabor; Nojima, Nobuyuki; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Kondo, Takashi

    2015-01-01

    Electron paramagnetic resonance (EPR)-spin trapping and flow cytometry were used to identify free radicals generated using argon-cold atmospheric plasma (Ar-CAP) in aqueous solutions and intracellularly in comparison with those generated by X-irradiation. Ar-CAP was generated using a high-voltage power supply unit with low-frequency excitation. The characteristics of Ar-CAP were estimated by vacuum UV absorption and emission spectra measurements. Hydroxyl (·OH) radicals and hydrogen (H) atoms in aqueous solutions were identified with the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO), and phenyl N-t-butylnitrone (PBN). The occurrence of Ar-CAP-induced pyrolysis was evaluated using the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) in aqueous solutions of DNA constituents, sodium acetate, and L-alanine. Human lymphoma U937 cells were used to study intracellular oxidative stress using five fluorescent probes with different affinities to a number of reactive species. The analysis and quantification of EPR spectra revealed the formation of enormous amounts of ·OH radicals using Ar-CAP compared with that by X-irradiation. Very small amounts of H atoms were detected whereas nitric oxide was not found. The formation of ·OH radicals depended on the type of rare gas used and the yield correlated inversely with ionization energy in the order of krypton > argon = neon > helium. No pyrolysis radicals were detected in aqueous solutions exposed to Ar-CAP. Intracellularly, ·OH, H2O2, which is the recombination product of ·OH, and OCl- were the most likely formed reactive oxygen species after exposure to Ar-CAP. Intracellularly, there was no practical evidence for the formation of NO whereas very small amounts of superoxides were formed. Despite the superiority of Ar-CAP in forming ·OH radicals, the exposure to X-rays proved more lethal. The mechanism of free radical formation in aqueous solutions and an intracellular milieu is discussed. PMID:26318000

  3. EPR-Spin Trapping and Flow Cytometric Studies of Free Radicals Generated Using Cold Atmospheric Argon Plasma and X-Ray Irradiation in Aqueous Solutions and Intracellular Milieu.

    PubMed

    Uchiyama, Hidefumi; Zhao, Qing-Li; Hassan, Mariame Ali; Andocs, Gabor; Nojima, Nobuyuki; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Kondo, Takashi

    2015-01-01

    Electron paramagnetic resonance (EPR)-spin trapping and flow cytometry were used to identify free radicals generated using argon-cold atmospheric plasma (Ar-CAP) in aqueous solutions and intracellularly in comparison with those generated by X-irradiation. Ar-CAP was generated using a high-voltage power supply unit with low-frequency excitation. The characteristics of Ar-CAP were estimated by vacuum UV absorption and emission spectra measurements. Hydroxyl (·OH) radicals and hydrogen (H) atoms in aqueous solutions were identified with the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO), and phenyl N-t-butylnitrone (PBN). The occurrence of Ar-CAP-induced pyrolysis was evaluated using the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) in aqueous solutions of DNA constituents, sodium acetate, and L-alanine. Human lymphoma U937 cells were used to study intracellular oxidative stress using five fluorescent probes with different affinities to a number of reactive species. The analysis and quantification of EPR spectra revealed the formation of enormous amounts of ·OH radicals using Ar-CAP compared with that by X-irradiation. Very small amounts of H atoms were detected whereas nitric oxide was not found. The formation of ·OH radicals depended on the type of rare gas used and the yield correlated inversely with ionization energy in the order of krypton > argon = neon > helium. No pyrolysis radicals were detected in aqueous solutions exposed to Ar-CAP. Intracellularly, ·OH, H2O2, which is the recombination product of ·OH, and OCl- were the most likely formed reactive oxygen species after exposure to Ar-CAP. Intracellularly, there was no practical evidence for the formation of NO whereas very small amounts of superoxides were formed. Despite the superiority of Ar-CAP in forming ·OH radicals, the exposure to X-rays proved more lethal. The mechanism of free radical formation in aqueous solutions and an intracellular milieu is discussed. PMID:26318000

  4. Intravascular coagulation and osteonecrosis.

    PubMed

    Jones, J P

    1992-04-01

    Current evidence suggests that intravascular coagulation (IC), an intermediary mechanism, is the most likely final common pathway by which intraosseous fat embolism causes nontraumatic osteonecrosis (ON). Stage 1A lesions (fatty osteocytic necrosis) appear to progress to classic Stage 1B lesions (ischemic degeneration of necrotic osteocytes and adipocytes) when the ischemic threshold is exceeded by absolute subchondral fat overload with insufficient local clearance of procoagulants, especially tissue thromboplastin. The result is vascular stasis, hypercoagulability, endothelial damage (by free fatty acids) and IC, especially if there is coexistent subchondral vasoconstriction and impaired secondary fibrinolysis. Osteonecrosis can be produced in animals by IC, which begins in the vulnerable subchondral microcirculation (Arthus phenomenon). Cartography (embolic scintimetry with superselective angiography) indicates early complete devascularization of the femoral head, suggesting progressive venous and retrograde arterial thrombosis. Increased plasma fibrinopeptide A and direct histologic evidence of intraosseous thromboses and peripheral hemorrhages further indicate that IC is the final pathway. Best evidence are 51 ON lesions complicating disseminated IC in eight children (Shwartzman phenomenon), with collateral histologic evidence of intraosseous thrombosis and ON. PMID:1532547

  5. 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

    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

    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

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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.

  7. Dust coagulation in ISM

    NASA Technical Reports Server (NTRS)

    Chokshi, Arati; Tielens, Alexander G. G. M.; Hollenbach, David

    1989-01-01

    Coagulation is an important mechanism in the growth of interstellar and interplanetary dust particles. The microphysics of the coagulation process was theoretically analyzed as a function of the physical properties of the coagulating grains, i.e., their size, relative velocities, temperature, elastic properties, and the van der Waal interaction. Numerical calculations of collisions between linear chains provide the wave energy in individual particles and the spectrum of the mechanical vibrations set up in colliding particles. Sticking probabilities are then calculated using simple estimates for elastic deformation energies and for the attenuation of the wave energy due to absorption and scattering processes.

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

    NASA Astrophysics Data System (ADS)

    Ctibor, P.; Pala, Z.; Sedl?ek, J.; tengl, V.; P, I.; Zahoranov, T.; Nehasil, V.

    2012-06-01

    Titanium dioxide coatings were sprayed by a water-stabilized plasma gun to form robust self-supporting bodies with a photocatalytically active surface. Agglomerated nanometric powder was used as a feedstock. In one case argon was used as a powder-feeding as well as coating-cooling gas whereas in the other case nitrogen was used. Stainless steel was used as a substrate and the coatings were released after the cooling. Over one millimeter thick self-supporting bodies were studied by XRD, HR-TEM, XPS, Raman spectroscopy, UV-VIS spectrophotometry and photocatalytic tests. Selected tests were done at the surface as well as at the bottom side representing the contact surface with the substrate during the spray process. Porosity was studied by image analysis on polished cross sections where also microhardness was measured. The dominant phase present in the sprayed samples was rutile, whereas anatase was only a minor component. The hydrogen content in the nitrogen-assisted coating was higher, but the character of the optical absorption edge remained the same for both samples. Photoelectron spectroscopy revealed differences in the character of the O1s peak between both samples. The photocatalytic activity was tested by decomposition of acetone at UV illumination, whereas also the end productsCO and CO2were monitored. The nitrogen-assisted coating was revealed as a more efficient photocatalyst. Certain aspects of a thermal post-treatment on the coatings are discussed as well. Color and electrical conductivity are markedly changed at annealing at 760 C, whereas only very small changes of the as-sprayed coating character correspond to annealing at 500 C.

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

    SciTech Connect

    Ye, Rubin; Ishigaki, Takamasa; Taguchi, Hiroyuki; Ito, Shigeru; Murphy, Anthony B.; Lange, Hubert

    2006-11-15

    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.

  10. Coagulation and Mental Disorders

    PubMed Central

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

    2014-01-01

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

  11. First principles transport coefficients and reaction rates of Ar{sub 2}{sup +} ions in argon for cold plasma jet modeling

    SciTech Connect

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

    2014-10-07

    Momentum-transfer collision cross-sections and integral collision cross-sections for the collision-induced dissociation are calculated for collisions of ionized argon dimers with argon atoms using a nonadiabatic semiclassical method with the electronic Hamiltonian calculated on the fly via a diatomics-in-molecules semiempirical model as well as inverse-method modeling based on simple isotropic rigid-core potential. The collision cross-sections are then used in an optimized Monte Carlo code for evaluations of the Ar{sub 2}{sup +} mobility in argon gas, longitudinal diffusion coefficient, and collision-induced dissociation rates. A thorough comparison of various theoretical calculations as well as with available experimental data on the Ar{sub 2}{sup +} mobility and collision cross-sections is performed. Good agreement is found between both theoretical approaches and the experiment. Analysis of the role of inelastic processes in Ar{sub 2}{sup +}/Ar collisions is also provided.

  12. Speciation of arsenic in human nail and hair from arsenic-affected area by HPLC-inductively coupled argon plasma mass spectrometry.

    PubMed

    Mandal, Badal Kumar; Ogra, Yasumitsu; Suzuki, Kazuo T

    2003-06-01

    Nail and hair are rich in fibrous proteins, i.e., alpha-keratins that contain abundant cysteine residues (up to 22% in nail and 10-14% in hair). Although they are metabolically dead materials in the epidermis, the roots are highly influenced by the health status of the living beings and their analyses are used as a tool to monitor occupational and environmental exposure to toxic elements. The aims of the present study are to speciate arsenicals in human nail and hair and also to judge whether they should be used as a biomarker to arsenic (As) exposure and/or toxicity. All human fingernail and hair samples (n = 47) were collected from the As-affected area of West Bengal, India. Speciation of arsenicals in water extracts of fingernails and hair at 90 degrees C was carried out by HPLC-inductively coupled argon plasma mass spectrometer (ICP MS). Fingernails contained iAs(III) (58.6%), iAs(V) (21.5), MMA(V) (7.7), DMA(III) (9.2), and DMA(V) (3.0), and hair contained iAs(III) (60.9%), iAs(V) (33.2), MMA(V) (2.2), and DMA(V) (3.6). Fingernails contained DMA(III), but hair did not. The higher percentage of iAs(III) both in fingernails and hair than that of iAs(V) suggests more affinity of iAs(III) to keratin. Although all arsenicals in fingernails and hair correlate to As exposure positively, As speciation in fingernails seems to be more correlated with arsenism than that in hair. Exogenous contamination is a confounding factor for hair to consider it as a biomarker, whereas this is mostly absent in fingernails, which recommends it to be a better biomarker to arsenic exposure. DMA(III) content in fingernails and DMA(V) contents in both fingernails and hair could be the biomarker to As exposure. PMID:12781625

  13. 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)

    Roman, W. C.

    1979-01-01

    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.

  14. Intrinsic coagulation pathway: an activation threshold.

    PubMed

    Pokhilko, A V

    2000-08-01

    The activation threshold for the intrinsic pathway of coagulation was experimentally determined in stirred recalcified plasma from the dependence of plasma clotting time after activation by celite. Concentration of factor XIa was used as a measure of activation. At free calcium concentrations below 0.45 mM, plasma clotting time depended nonlinearly on the factor XIa concentration: with decreasing concentration of factor XIa (or celite), the clotting time dramatically increased until no coagulation was observed at concentrations of factor XIa below the threshold. As the free calcium concentration increased, the threshold concentration of factor XIa sharply decreased, from 30 pM at 0.35 mM free calcium to less than 3 pM at 0.45 mM. In the range of free calcium concentrations from 0.45 mM to physiologic ones, plasma coagulated even in the absence of celite in plastic cuvettes. This fact and extremely low threshold concentrations of factor XI (on the order of 0.5 pM) preclude determining the factor XI threshold at physiologic free calcium. As factor XIa is localized to the activating surfaces, observing the local surface concentrations of factor XIa and the dynamics of fibrin formation in systems without stirring may solve the problem. PMID:10942795

  15. Disseminated intravascular coagulation.

    PubMed

    Venugopal, A

    2014-09-01

    Disseminated intravascular coagulation (DIC) is a reflection of an underlying systemic disorder which affects the coagulation system, simultaneously resulting in pro-coagulant activation, fibrinolytic activation, and consumption coagulopathy and finally may result in organ dysfunction and death. Though septicaemia is the most common cause of DIC, several other conditions can also lead to it. A diagnosis of DIC should be made only in the presence of a causative factor supported by repeated laboratory tests for coagulation profile and clotting factors. An effective scoring system helps to detect an overt DIC and a high score closely correlates with mortality. Treatment of DIC is aimed at combating the underlying disorder followed by supportive management. Low molecular weight heparin is advocated in special situations whereas anti-thrombin III and activated protein C are of doubtful value. Early diagnosis and prompt treatment backed by laboratory support can reduce the morbidity and mortality associated with it. The methodology of search for this review article involved hand search from text books and internet search using Medline (via PubMed) using key words DIC, thrombosis, fibrin degradation products, anti-thrombin and tissue factor for the last 25 years and also recent evidence-based reviews. PMID:25535423

  16. Disseminated intravascular coagulation

    PubMed Central

    Venugopal, A

    2014-01-01

    Disseminated intravascular coagulation (DIC) is a reflection of an underlying systemic disorder which affects the coagulation system, simultaneously resulting in pro-coagulant activation, fibrinolytic activation, and consumption coagulopathy and finally may result in organ dysfunction and death. Though septicaemia is the most common cause of DIC, several other conditions can also lead to it. A diagnosis of DIC should be made only in the presence of a causative factor supported by repeated laboratory tests for coagulation profile and clotting factors. An effective scoring system helps to detect an overt DIC and a high score closely correlates with mortality. Treatment of DIC is aimed at combating the underlying disorder followed by supportive management. Low molecular weight heparin is advocated in special situations whereas anti-thrombin III and activated protein C are of doubtful value. Early diagnosis and prompt treatment backed by laboratory support can reduce the morbidity and mortality associated with it. The methodology of search for this review article involved hand search from text books and internet search using Medline (via PubMed) using key words DIC, thrombosis, fibrin degradation products, anti-thrombin and tissue factor for the last 25 years and also recent evidence-based reviews. PMID:25535423

  17. Coagulation abnormalities in sepsis.

    PubMed

    Tsao, Cheng-Ming; Ho, Shung-Tai; Wu, Chin-Chen

    2015-03-01

    Although the pathophysiology of sepsis has been elucidated with the passage of time, sepsis may be regarded as an uncontrolled inflammatory and procoagulant response to infection. The hemostatic changes in sepsis range from subclinical activation of blood coagulation to acute disseminated intravascular coagulation (DIC). DIC is characterized by widespread microvascular thrombosis, which contributes to multiple organ dysfunction/failure, and subsequent consumption of platelets and coagulation factors, eventually causing bleeding manifestations. The diagnosis of DIC can be made using routinely available laboratory tests, scoring algorithms, and thromboelastography. In this cascade of events, the inhibition of coagulation activation and platelet function is conjectured as a useful tool for attenuating inflammatory response and improving outcomes in sepsis. A number of clinical trials of anticoagulants were performed, but none of them have been recognized as a standard therapy because recombinant activated protein C was withdrawn from the market owing to its insufficient efficacy in a randomized controlled trial. However, these subgroup analyses of activated protein C, antithrombin, and thrombomodulin trials show that overt coagulation activation is strongly associated with the best therapeutic effect of the inhibitor. In addition, antiplatelet drugs, including acetylsalicylic acid, P2Y12 inhibitors, and glycoprotein IIb/IIIa antagonists, may reduce organ failure and mortality in the experimental model of sepsis without a concomitant increased bleeding risk, which should be supported by solid clinical data. For a state-of-the-art treatment of sepsis, the efficacy of anticoagulant and antiplatelet agents needs to be proved in further large-scale prospective, interventional, randomized validation trials. PMID:25544351

  18. Type of precursor and synthesis of silicon oxycarbide (SiO{sub x}C{sub y}H) thin films with a surfatron microwave oxygen/argon plasma

    SciTech Connect

    Walkiewicz-Pietrzykowska, Agnieszka; Espinos, J. P.; Gonzalez-Elipe, Agustin R.

    2006-07-15

    Siliconelike thin films (i.e., SiO{sub x}C{sub y}H{sub z}) were prepared in a microwave plasma enhanced chemical vapor deposition reactor from structurally different organosilicon precursors [i.e., hexamethyldisiloxane (HMDSO), dimethylsilane (DMS), and tetramethylsilane (TMS)]. The films were deposited at room temperature by using different oxygen/argon ratios in the plasma gas. By changing the type of precursor and the relative concentration of oxygen in the plasma, thin films with different compositions (i.e., O/C ratio) and properties are obtained. In general, raising the oxygen concentration in the plasma produces the progressive removal of the organic moieties from the films whose composition and structure then approach those of silicon dioxide. The deposition rate was highly dependent on the type of precursor, following the order HMDSO>>DMS>TMS. The polarizabilities, optical band gaps, and surface free energy of the films also depended on the thin film composition and structure. It is proposed that the Si-O bonds existing in HMDSO is the main factor controlling the distinct reactivity of this precursor and is also responsible for the different compositions and properties of the SiO{sub x}C{sub y}H{sub z} thin films prepared with very low or no oxygen in the plasma gas.

  19. Simultaneous measurements of OH(A) and OH(X) radicals in microwave argon plasma assisted combustion of methane/air mixtures using optical emission spectroscopy and cavity ringdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Wang, Chuji; Laser Spectroscopy; Plasma Team

    2013-09-01

    We developed a new plasma assisted combustion system employing a continuous atmospheric argon microwave plasma jet to enhance combustion of methane/air mixtures in different fuel equivalence ratios (?) . The combustor has three distinct reaction zones of pure plasma zone, the hybrid plasma-flame zone and pure flame zone which were well defined by their emission spectra. Optical emission spectroscopy (OES) was used to exam the excited species including OH(A) and results showed that OH(A) intensities gradually increased in plasma zone and rapidly increased in hybrid zone and then dramatically decreased to a very low level in flame zone. In addition to OES, pulsed cavity ringdown spectroscopy (CRDS) was utilized to measure the absolute number density of OH(X) in the flame zone at ? = 0.51, 0.87, 1.10 and 1.45. Different OH(X) number densities and density profiles were observed comparing rich and lean combustions. At ? = 0.51, the OH(X, V'' = 0, J'' = 0.5) number density increased from 2.29 1015 molecule cm-3 at the combustor nozzle to maximum 3.13 105 molecule cm-3 at 2 mm downstream, and then gradually decreased to the lowest detectable level of 0.12 1015 molecule cm-3 in the far downstream. Supported by NSF through No. CBET-1066486.

  20. [Effects of Interaction of Ozonation and Coagulation on Coagulation Results].

    PubMed

    Liu, Hai-long; Guo, Xue-feng; Wang, Min-hui; Jiao, Ru-yuan; Shi, Jian

    2015-09-01

    Two strategies, ozonation-coagulation combination (OCC, ozone and coagulant dosed at meantime) and preozonation coagulation (PC, coagulant dosed after ozone died away) were used to treat synthesized water. Different effects of oxidation and coagulation, disinfection by-products formation potentials (DBPFP) in the same water were detected in order to study the influence of interaction of ozonation and coagulation (IOC) on treated water characteristics. Results show that there are remarkable differences between OCC and PC. IOC effects take place during OCC process, which results in variations of the distribution of hydrolyzed species of coagulant. And this is an important reason which impairs efficiency of coagulation. Turbidity after OCC was higher than that of PC. One of the main reasons is that ozone reduced the content of Alb species which was built during coagulant hydrolyzation. Cl-DBPFP in OCC outlet water were lower than those in PC because oxidized destruction of DBP precursors were enhanced by catalyzed ozonation by AlCl3 along with its other hydrolyzed species. Removals of MCAA and CF formation potentials by OCC were significantly higher than those by PC, MCAAFP were 5. 6 g . L-1 and 16. 9 g . L-1 respectively, and CFFP were 12. 5 g . L-1 and 24. 1 g . L-1 respectively. Coagulation results and DBP formations are significantly affected by interaction of ozonation and coagulation; and it should be a noticeable point of water safety if ozonation and coagulation are employed together. Thus times and spots between ozone and coagulant should be defined clearly in correlational researches and water treatment application. PMID:26717689

  1. 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)

    Yepishina, S. G.

    1974-01-01

    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.

  2. Quantification of sphingosine 1-phosphate by validated LC-MS/MS method revealing strong correlation with apolipoprotein M in plasma but not in serum due to platelet activation during blood coagulation.

    PubMed

    Frej, Cecilia; Andersson, Anders; Larsson, Benny; Guo, Li Jun; Norstrm, Eva; Happonen, Kaisa E; Dahlbck, Bjrn

    2015-11-01

    Sphingosine 1-phosphate (S1P) is a signalling sphingolipid affecting multiple cellular functions of vascular and immune systems. It circulates at submicromolar levels bound to HDL-associated apolipoprotein M (apoM) or to albumin. S1P in blood is mainly produced by platelets and erythrocytes, making blood sampling for S1P quantification delicate. Standardisation of sampling is thereby of great importance to obtain robust data. By optimising and characterising the extraction procedure and the LC-MS/MS analysis, we have developed and validated a highly specific and sensitive method for S1P quantification. Blood was collected from healthy individuals (n?=?15) to evaluate the effects of differential blood sampling on S1P levels. To evaluate correlation between S1P and apoM in different types of plasma and serum, apoM was measured by ELISA. The method showed good accuracy and precision in the range of 0.011 to 0.9?M with less than 0.07% carryover. We found that the methanol precipitation used to extract S1P co-extracted apoM and several other HDL-proteins from plasma. The platelet-associated S1P was released during coagulation, thus increasing the S1P concentration to double in serum as compared to that in plasma. Gel filtration chromatography revealed that the platelet-released S1P was mainly bound to albumin. This explains why the strong correlation between S1P and apoM levels in plasma is lost upon the clotting process and hence not observed in serum. We have developed, characterised and validated an efficient, highly sensitive and specific method for the quantification of S1P in biological material. PMID:26377937

  3. Overview of the coagulation system

    PubMed Central

    Palta, Sanjeev; Saroa, Richa; Palta, Anshu

    2014-01-01

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

  4. Lunar exospheric argon modeling

    NASA Astrophysics Data System (ADS)

    Grava, Cesare; Chaufray, J.-Y.; Retherford, K. D.; Gladstone, G. R.; Greathouse, T. K.; Hurley, D. M.; Hodges, R. R.; Bayless, A. J.; Cook, J. C.; Stern, S. A.

    2015-07-01

    Argon is one of the few known constituents of the lunar exosphere. The surface-based mass spectrometer Lunar Atmosphere Composition Experiment (LACE) deployed during the Apollo 17 mission first detected argon, and its study is among the subjects of the Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) and Lunar Atmospheric and Dust Environment Explorer (LADEE) mission investigations. We performed a detailed Monte Carlo simulation of neutral atomic argon that we use to better understand its transport and storage across the lunar surface. We took into account several loss processes: ionization by solar photons, charge-exchange with solar protons, and cold trapping as computed by recent LRO/Lunar Orbiter Laser Altimeter (LOLA) mapping of Permanently Shaded Regions (PSRs). Recycling of photo-ions and solar radiation acceleration are also considered. We report that (i) contrary to previous assumptions, charge exchange is a loss process as efficient as photo-ionization, (ii) the PSR cold-trapping flux is comparable to the ionization flux (photo-ionization and charge-exchange), and (iii) solar radiation pressure has negligible effect on the argon density, as expected. We determine that the release of 2.6 × 1028 atoms on top of a pre-existing argon exosphere is required to explain the maximum amount of argon measured by LACE. The total number of atoms (1.0 × 1029) corresponds to ∼6700 kg of argon, 30% of which (∼1900 kg) may be stored in the cold traps after 120 days in the absence of space weathering processes. The required population is consistent with the amount of argon that can be released during a High Frequency Teleseismic (HFT) Event, i.e. a big, rare and localized moonquake, although we show that LACE could not distinguish between a localized and a global event. The density of argon measured at the time of LACE appears to have originated from no less than four such episodic events. Finally, we show that the extent of the PSRs that trap argon, 0.007% of the total lunar surface, is consistent with the presence of adsorbed water in such PSRs.

  5. [Protein C and coagulation in sepsis].

    PubMed

    D'Angelo, A; Della Valle, P; Giudici, D; Vigan D'Angelo, S

    2004-05-01

    The last few years have clarified the tight link between inflammation and coagulation. In addition to the identification of new regulatory mechanisms of the coagulation system and of an explosive number of mediators of inflammation, it is now clear that the existence of a positive feed-back between inflammation and coagulation leads to reciprocal activation of both pathways. Plasma levels of acute phase proteins involved in coagulation and fibrinolysis are elevated during inflammation, while natural anticoagulant mechanisms are depressed. Pro-inflammatory cytokines "activate" cell membranes exposed to flowing blood (endothelium, platelets, monocytes, neutrophils) which from physiologically inert or anticoagulant become procoagulant. Increased tissue factor expression results in increased thrombin formation within the microcirculation. Thrombin is central to fibrin deposition but it also plays a key role in cell-mediated mechanisms involving inflammation, cell proliferation and activation of the natural anticoagulant protein C. Depression of natural anticoagulant mechanisms, occurring in severe sepsis, results in uncontrolled thrombin formation, with pro-inflammatory activity prevailing, and the feed-back loop of inflammation and coagulation ultimately leading to multi-organ failure. However, both in the clinical setting and in animal experiments, heparin or direct anticoagulants have shown no effect on survival even if blocking fibrin deposition. Organ failure is only partially due to the thrombotic occlusion of the microcirculation, while other mechanisms of endothelial damage are probably more relevant in the development of ischemia. The endothelium is central to the maintenance of the natural anticoagulant mechanisms (TFPI, antithrombin, protein C). The protein C system, in addition to dumping thrombin formation, specifically modulates inflammation by cell signaling. This system is markedly depressed in severe sepsis. The infusion of activated protein C, or restoring normal levels of protein C within the circulation - depending on the individual bleeding risk are powerful tools to treat the endothelitis responsible for the clinical sequelae of severe sepsis. PMID:15181414

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

    PubMed Central

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

    2014-01-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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.

  8. Depleted Argon from Underground Sources

    SciTech Connect

    Back, H. O.; Galbiati, C.; Goretti, A.; Loer, B.; Montanari, D.; Mosteiro, P.; Alexander, T.; Alton, A.; Rogers, H.; Kendziora, C.; Pordes, S.

    2011-04-27

    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.

  9. Depleted Argon from Underground Sources

    NASA Astrophysics Data System (ADS)

    Back, H. O.; Alexander, T.; Alton, A.; Galbiati, C.; Goretti, A.; Kendziora, C.; Loer, B.; Montanari, D.; Mosteiro, P.; Pordes, S.; Rogers, H.

    2011-04-01

    Argon is a strong scintillator and an ideal target for Dark Matter detection; however 39Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in 39Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO2 well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO2. We first concentrate the argon locally to 3% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation, and then the N2 and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO2 facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

  10. SLD liquid argon calorimeter

    SciTech Connect

    Vella, E.; SLD Collaboration

    1992-10-01

    The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z{sup 0} decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z{sup 0} events) is discussed.

  11. SLD liquid argon calorimeter

    SciTech Connect

    Vella, E.

    1992-10-01

    The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z[sup 0] decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z[sup 0] events) is discussed.

  12. Evaluation of coagulation and fibrinolysis in horses with atrial fibrillation.

    PubMed

    de Sols, Cristobal Navas; Reef, Virginia B; Slack, JoAnn; Jose-Cunilleras, Eduard

    2016-01-15

    OBJECTIVE To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease. DESIGN Case-control study. ANIMALS Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]). PROCEDURES Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activity) in horses were recorded to assess coagulation and fibrinolysis. Historical and clinical variables, as associated with a hypercoagulable state in other species, were also recorded. RESULTS Horses with atrial fibrillation and control horses lacked clinical signs of hypercoagulation or thromboembolism. Compared with control horses, horses with atrial fibrillation had significantly lower antithrombin activity. No significant differences in plasma fibrinogen and D-dimer concentrations and prothrombin and activated partial thromboplastin times existed between horse groups. In horses with atrial fibrillation versus control horses, a significantly larger proportion had an abnormal plasma D-dimer concentration (10/25 vs 2/17), test results indicative of subclinical activated coagulation (18/25 vs 6/17), or abnormal coagulation test results (25/121 vs 7/85), respectively. CONCLUSIONS AND CLINICAL RELEVANCE Horses with atrial fibrillation did not have clinical evidence of a hypercoagulable state, but a higher proportion of horses with atrial fibrillation, compared with control horses, did have subclinical activated coagulation on the basis of standard coagulation test results. PMID:26720087

  13. Coagulant modulates the hypocholesterolemic effect of tofu (coagulated soymilk).

    PubMed

    Oboh, Ganiyu

    2007-06-01

    The recent increase in soymilk and tofu (coagulated soymilk) consumption, especially in Western countries, is due to the recognition of the health benefits of soy foods; consumption of soybean would prevent heart diseases. Since the amount and the type of coagulated biomolecules (such as isoflavones) will vary with the type of coagulant, this will inevitably alter their biological activity. This study sought to assess the effect of some coagulants (calcium chloride, alum, and steep water from pap production) commonly used in the production of tofu in Nigeria on the serum cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels in albino rats fed tofu for 14 days. The results of this study revealed that there was a significant difference (P < .05) in the total phenol [calcium chloride (0.9%), alum (0.8%), and steep water (1.2%)] content of all the tofu produced. Furthermore, feeding albino rats with tofu and water ad libitum for 14 days caused a significant decrease (P < .05) in serum cholesterol and LDL when compared with the control. Conversely, there was a significant increase (P < .05) in serum HDL when compared with the control. However, rats fed steep water-coagulated tofu had the lowest serum levels of cholesterol and LDL, followed by those fed alum- and calcium chloride-coagulated tofu, respectively, while those fed with alum-coagulated tofu had the highest serum HDL level, closely followed by those fed steep water-coagulated tofu. It was therefore concluded that of all the coagulants, steep water appeared to be the most promising coagulant with regard to the production of tofu with a high hypocholesterolemic effect based on the low serum cholesterol and LDL levels and high HDL level. PMID:17651081

  14. Blood Coagulation, Inflammation and Malaria

    PubMed Central

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

    2010-01-01

    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. PMID:18260002

  15. Thermophysical properties of argon

    SciTech Connect

    Jaques, A.

    1988-02-01

    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)

  16. A novel coagulation inhibitor from Schistosoma japonicum.

    PubMed

    Ranasinghe, Shiwanthi L; Fischer, Katja; Gobert, Geoffrey N; McManus, Donald P

    2015-12-01

    Little is known about the molecular mechanisms whereby the human blood fluke Schistosoma japonicum is able to survive in the host venous blood system. Protease inhibitors are likely released by the parasite enabling it to avoid attack by host proteolytic enzymes and coagulation factors. Interrogation of the S. japonicum genomic sequence identified a gene, SjKI-1, homologous to that encoding a single domain Kunitz protein (Sjp_0020270) which we expressed in recombinant form in Escherichia coli and purified. SjKI-1 is highly transcribed in adult worms and eggs but its expression was very low in cercariae and schistosomula. In situ immunolocalization with anti-SjKI-1 rabbit antibodies showed the protein was present in eggs trapped in the infected mouse intestinal wall. In functional assays, SjKI-1 inhibited trypsin in the picomolar range and chymotrypsin, neutrophil elastase, FXa and plasma kallikrein in the nanomolar range. Furthermore, SjKI-1, at a concentration of 75 m, prolonged 2-fold activated partial thromboplastin time of human blood coagulation. We also demonstrate that SjKI-1 has the ability to bind Ca++. We present, therefore, characterization of the first Kunitz protein from S. japonicum which we show has an anti-coagulant properties. In addition, its inhibition of neutrophil elastase indicates SjKI-1 have an anti-inflammatory role. Having anti-thrombotic properties, SjKI-1 may point the way towards novel treatment for hemostatic disorders. PMID:26463744

  17. Brain neoplasms and coagulation.

    PubMed

    Magnus, Nathalie; D'Asti, Esterina; Garnier, Delphine; Meehan, Brian; Rak, Janusz

    2013-11-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  19. Microfluidics and Coagulation Biology

    PubMed Central

    Colace, Thomas V.; Tormoen, Garth W.

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  1. Spectroscopic characterization of femtosecond laser filament in argon gas

    SciTech Connect

    Liu, W.; Bernhardt, J.; Theberge, F.; Chin, S. L.; Chateauneuf, M.; Dubois, J.

    2007-08-01

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

  2. Argon frost continuous cryopump for fusion applications

    SciTech Connect

    Foster, C.A.; McCurdy, H.C.

    1993-12-01

    A cryopumping system based on the snail continuous cryopump concept is being developed for fusion applications under a DOE SBIR grant. The primary pump is a liquid helium cooled compound pump designed to continuously pump and fractionate deuterium/tritium and helium. The D/T pumping stage is a 500 mm bore cryocondensation pump with a nominal pumping speed of 45,000 L/s. It will be continuously regenerated by a snail regeneration by head every 12 minutes. Continuous regeneration will dramatically reduce the vulnerable tritium inventory in a fusion reactor. Operating at an inlet pressure of 1 millitorr, eight of these pumps could pump the projected D/T flow in the ITER CDA design while reducing the inventory of tritium in the pumping system from 630 to 43 grams. The helium fraction will be pumped in a compound argon frost stage. This stage will also operate continuously with a snail regeneration head. In addition the argon spray head will be enclosed inside the snail, thereby removing gaseous argon from the process chamber. Since the cryocondensation stage will intercept over 90% of the D/T/H steam, a purified stream from this stage could be directly reinjected into the plasma as gas or pellets, thereby bypassing the isotope separation system and further simplifying the fuel cycle. Experiments were undertaken in Phase I which demonstrated continuous cryosorption pumping of hydrogen on CO{sub 2} and argon frosts. The pumping system and its relevance to fusion reactor pumping will be discussed.

  3. Isentropic Compression of Argon

    SciTech Connect

    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

    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.

  4. Numerical Modeling of Plasmas in which Nanoparticles Nucleate and Grow

    NASA Astrophysics Data System (ADS)

    Agarwal, Pulkit

    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.

  5. Whole blood coagulation analyzers.

    PubMed

    1997-08-01

    Whole blood Coagulation analyzers (WBCAs) are widely used point-of-care (POC) testing devices found primarily in cardiothoracic surgical suites and cardia catheterization laboratories. Most of these devices can perform a number of coagulation tests that provide information about a patient's blood clotting status. Clinicians use the results of the WBCA tests, which are available minutes after applying a blood sample, primarily to monitor the effectiveness of heparin therapy--an anticoagulation therapy used during cardiopulmonary bypass (CPB) surgery, angioplasty, hemodialysis, and other clinical procedures. In this study we evaluated five WBCAs from four suppliers. Our testing focused on the applications for which WBCAs are primarily used: Monitoring moderate to high heparin levels, as would be required, for example, during CPB are angioplasty. For this function, WCBAs are typically used to perform an activated clotting time (ACT) test or, as one supplier refers to its test, a heparin management test (HMT). All models included in this study offered an ACT test or an HMT. Monitoring low heparin levels, as would be required, for example,during hemodialysis. For this function, WBCAs would normally be used to perform either a low-range ACT (LACT) test or a whole blood activated partial thromboplastin time (WBAPTT) test. Most of the evaluated units could perform at least one of these tests; one unit did not offer either test and was therefore not rated for this application. We rated and ranked each evaluated model separately for each of these two applications. In addition, we provided a combined rating and ranking that considers the units' appropriateness for performing both application. We based our conclusions on a unit's performance and humans factor design, as determined by our testing, and on its five-year life-cycle cost, as determined by our net present value (NPV) analysis. While we rated all evaluated units acceptable for each appropriate category, we did identify some significant differences that enabled us to rank the units in order of preference. We have included a Selection, Purchasing, and use guide at the end of this study to help facilities identify the unit that will best meet their needs. PMID:9283920

  6. Disorders of coagulation in pregnancy.

    PubMed

    Katz, D; Beilin, Y

    2015-12-01

    The process of haemostasis is complex and is further complicated in the parturient because of the physiological changes of pregnancy. Understanding these changes and the impact that they have on the safety profile of the anaesthetic options for labour and delivery is crucial to any anaesthetist caring for the parturient. This article analyses current theories on coagulation and reviews the physiological changes to coagulation that occur during pregnancy and the best methods with which to evaluate coagulation. Finally, we examine some of the more common disorders of coagulation that occur during pregnancy, including von Willebrand disease, common factor deficiencies, platelet disorders, the parturient on anticoagulants, and the more rare acute fatty liver of pregnancy, with a focus on their implications for neuraxial anaesthesia. PMID:26658204

  7. REMOVING TRIHALOMETHANE PRECURSORS BY COAGULATION

    EPA Science Inventory

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

  8. Microfluidics and coagulation biology.

    PubMed

    Colace, Thomas V; Tormoen, Garth W; McCarty, Owen J T; Diamond, Scott L

    2013-01-01

    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

  9. Cosmic dust synthesis by accretion and coagulation

    NASA Technical Reports Server (NTRS)

    Praburam, G.; Goree, J.

    1995-01-01

    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.

  10. Disseminated intravascular coagulation (DIC)

    MedlinePLUS

    ... serious disorder in which the proteins that control blood clotting become over active. ... Supportive treatments may include: Plasma transfusions to replace blood clotting factors if a large amount of bleeding is ...

  11. Argon Purification Reference and Recommendation

    SciTech Connect

    Wu, J.; /Fermilab

    1991-05-23

    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.

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

    SciTech Connect

    Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying

    2007-06-15

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    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 α-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.

  14. Endogenous plasma activated protein C levels and the effect of enoxaparin and drotrecogin alfa (activated) on markers of coagulation activation and fibrinolysis in pulmonary embolism

    PubMed Central

    2011-01-01

    Introduction There are no published data on the status of endogenous activated protein C (APC) in pulmonary embolism (PE), and no data on the effect of drotrecogin alfa (activated) (DAA) given in addition to therapeutic dose enoxaparin. Methods In this double-blind clinical trial, 47 patients with computed tomography (CT)-confirmed acute submassive PE treated with 1 mg/kg body weight of enoxaparin twice daily were randomized to groups receiving a 12-hour intravenous infusion of 6, 12, 18, or 24 ?g/kg/hour of DAA or a placebo. Blood samples were drawn before starting DAA infusion, after 4, 8 and 12 hours (at the end of the infusion period), and on treatment days 2, 3, 4, 5 and 6. Results Initial endogenous plasma activated protein C (APC) levels were 0.36 0.48 ng/ml (<0.10 to 1.72 ng/ml) and remained in the same range in the placebo group. APC levels in patients treated with DAA were 13.67 3.57 ng/ml, 32.71 8.76 ng/ml, 36.13 7.60 ng/ml, and 51.79 15.84 ng/ml in patients treated with 6, 12, 18, and 24 ?g/kg/hour DAA, respectively. In patients with a D-dimer level >4 mg/L indicating a high level of acute fibrin formation and dissolution, DAA infusion resulted in a more rapid drop in soluble fibrin, D-dimer, and fibrinogen/fibrin degradation products (FDP) levels, compared to enoxaparin alone. There was a parallel decline of soluble fibrin, D-dimer, FDP, and plasmin-plasmin inhibitor complex (PPIC) in response to treatment with enoxaparin DAA, with no evidence of a systemic profibrinolytic effect of the treatment. Conclusions In patients with acute submassive PE endogenous APC levels are low. DAA infusion enhances the inhibition of fibrin formation. Trial registration ClinicalTrials.gov: NCT00191724 PMID:21241489

  15. Coagulation of dielectric dust grains due to variable asymmetric charging

    SciTech Connect

    Manweiler, Jerry W.; Armstrong, Thomas P.; Cravens, Thomas E.

    1998-10-21

    Observational evidence of electrical forces acting significantly on small solids is present for both the modern solar system in Saturn's rings and the ancient solar system in chondritic meteorites. It is likely that grain-grain coagulation rates are affected by the distribution of charges on small grains. Plasma particle impacts and photoelectric effects can provide the charges. It appears that some charging is inevitable and that plasma grain interactions need to be evaluated to determine the size of the effect on coagulation rates. We apply the results of our previous charging work to models of the protoplanetary nebula. It is expected that the protoplanetary nebula is weakly ionized except in certain instances and locations such as: solar flares in the interior, ultraviolet radiation at the outer boundary, and during enhanced luminosity of the star. Since the grains we study are non-conducting and show strong dipole moments in flowing plasma, we modify the geometric cross sections to include the effects of flowing plasma on non-conducting grains with plasma mediated shielding. This paper provides results showing how plasma flow affects the processes involved in charging the grains--total charge and charge distribution. We calculate the modifications to the cross sections and subsequent changes in the coagulation rates.

  16. Effect of oxygen atoms dissociated by non-equilibrium plasma on flame of methane oxygen and argon pre-mixture gas

    NASA Astrophysics Data System (ADS)

    Akashi, Haruaki; Yoshinaga, Tomokazu; Sasaki, Koichi

    2014-10-01

    For more efficient way of combustion, plasma-assisted combustion has been investigated by many researchers. But it is very difficult to clarify the effect of plasma even on the flame of methane. Because there are many complex chemical reactions in combustion system. Sasaki et al. has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power. They also measured emission from Second Positive Band System of nitrogen during the irradiation. The emission indicates existence of high energy electrons which are accelerated by the microwave. The high energy electrons also dissociate oxygen molecules easily and oxygen atom would have some effects on the flame. But the dissociation ratio of oxygen molecules by the non-equilibrium plasma is significantly low, compared to that in the combustion reaction. To clarify the effect of dissociated oxygen atoms on the flame, dependence of dissociation ratio of oxygen on the flame has been examined using CHEMKIN. It is found that in the case of low dissociation ratio of 10-6, the ignition of the flame becomes slightly earlier. It is also found that in the case of high dissociation ratio of 10-3, the ignition time becomes significantly earlier by almost half. This work was supported by KAKENHI (22340170).

  17. Purification of coagulation factor VIII by immobilized metal affinity chromatography.

    PubMed

    Rodrigues, Estela S; Verinaud, Claudia I; Oliveira, Douglas S; Raw, Isaas; Lopes, Alexandre P Y; Martins, Elizabeth A L; Cheng, Elisabeth

    2015-01-01

    Factor VIII (FVIII) is a glycoprotein that plays an essential role in blood coagulation cascade. Purification of plasma-derived coagulation FVIII by direct application of plasma to a chromatographic column is a method of choice. Anion exchange column is a very powerful method because FVIII is strongly adsorbed, resulting in good activity recovery and high purification factor. However, vitamin-K-dependent coagulation factors coelute with FVIII. In the present study, we report the separation of vitamin-K-dependent coagulation proteins from FVIII using immobilized metal affinity chromatography (IMAC) with Cu(2+) as the metal ligand. Plasma was directly loaded to a Q Sepharose Big Beads column, and FVIII was recovered with 65% activity and a purification factor of approximately 50 times. Then, the Q Sepharose eluate was applied to the IMAC-Cu(2+) column, and FVIII was eluted with 200 mM imidazole, with up to 85% recovery of activity. The mass recovery in this fraction was less than 10% of the applied mass of protein. Vitamin-K-dependent proteins elute with imidazole concentrations of lower than 60 mM. Because of the difference in affinity, FVIII could be completely separated from the vitamin-K-dependent proteins in the IMAC column. PMID:25082654

  18. Effects of argon gas flow rate on the microstructure and micromechanical properties of supersonic plasma sprayed nanostructured Al2O3-13 wt.%TiO2 coatings

    NASA Astrophysics Data System (ADS)

    Li, Guo-lu; Ma, Jian-long; Wang, Hai-dou; Kang, Jia-jie; Xu, Bin-shi

    2014-08-01

    Nanostructured Al2O3-13 wt.%TiO2 (n-AT13) ceramic coatings were fabricated by supersonic plasma spray (SPS) using agglomerated powders. Effects of the argon gas flow rate (AGFR) on microstructure and micromechanical properties of n-AT13 ceramic coatings, which have been widely used to improve the wear and corrosion resistance, were investigated. The microstructure, porosity, micro-hardness, elastic modulus and fracture toughness of coatings were experimentally determined and characterized. The results showed that the measured data of micro-hardness, elastic modulus, fracture toughness and porosity followed Weibull distribution and had a large scattering. Micro-hardness, elastic modulus and fracture toughness exhibit a characteristic of bimodal distribution because of a bimodal distributional microstructure, which was composed of fully molten regions (FM) and partially molten regions (PM). With the increasing AGFR, the mean values and characteristic values of micro-hardness as well as elastic modulus increased and reached a local maximum and then decreased. However, the mean values and characteristic values for porosity as well as fracture toughness had opposite trends. Characteristic values and mean values of fracture toughness increased with the increase in values of porosity, but those of micro-hardness and elastic modulus were opposite.

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

    PubMed

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

    2014-05-01

    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

  20. The Argon Geochronology Experiment (AGE)

    NASA Technical Reports Server (NTRS)

    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

    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.

  1. Isentropic compression of argon

    SciTech Connect

    Veeser, L.R.; Ekdahl, C.A.; Oona, H.

    1997-06-01

    The compression was done in an MC-1 flux compression (explosive) generator, in order to study the transition from an insulator to a conductor. Since conductivity signals were observed in all the experiments (except when the probe is removed), both the Teflon and the argon are becoming conductive. The conductivity could not be determined (Teflon insulation properties unknown), but it could be bounded as being {sigma}=1/{rho}{le}8({Omega}cm){sub -1}, because when the Teflon breaks down, the dielectric constant is reduced. The Teflon insulator problem remains, and other ways to better insulate the probe or to measure the conductivity without a probe is being sought.

  2. 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)

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

    2013-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  4. Using a Systems Pharmacology Model of the Blood Coagulation Network to Predict the Effects of Various Therapies on Biomarkers

    PubMed Central

    Nayak, S; Lee, D; Patel-Hett, S; Pittman, DD; Martin, SW; Heatherington, AC; Vicini, P; Hua, F

    2015-01-01

    A number of therapeutics have been developed or are under development aiming to modulate the coagulation network to treat various diseases. We used a systems model to better understand the effect of modulating various components on blood coagulation. A computational model of the coagulation network was built to match in-house in vitro thrombin generation and activated Partial Thromboplastin Time (aPTT) data with various concentrations of recombinant factor VIIa (FVIIa) or factor Xa added to normal human plasma or factor VIII-deficient plasma. Sensitivity analysis applied to the model revealed that lag time, peak thrombin concentration, area under the curve (AUC) of the thrombin generation profile, and aPTT show different sensitivity to changes in coagulation factors concentrations and type of plasma used (normal or factor VIII-deficient). We also used the model to explore how variability in concentrations of the proteins in coagulation network can impact the response to FVIIa treatment. PMID:26312163

  5. [Efficacy of soft coagulation in thoracic surgery].

    PubMed

    Sato, Yukio

    2014-07-01

    The soft coagulation is a novel mode of electrosurgical device which automatically regulates its output voltage to stay below 190 Volts, causing pure coagulation without carbonization. The soft coagulation is available with bipolar and monopolar devices in thoracic surgery. Bipolar scissors can be applied for dissection of pulmonary vessels safely and efficiently without the damage to vessel wall. Monopolar soft coagulation can be applied to shrink bullous change of lung, cease air leakage from lung parenchyme or bleeding from pulmonary vessels. PMID:25138947

  6. Thermophysical properties of multi-shock compressed dense argon

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  7. Thermophysical properties of multi-shock compressed dense argon

    SciTech Connect

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

    2014-02-21

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

  8. Thermophysical properties of multi-shock compressed dense argon.

    PubMed

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

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models. PMID:24559345

  9. CONTROLLING COAGULATION DYSREGULATION IN XENOTRANSPLANTATION

    PubMed Central

    Cowan, Peter J.; Robson, Simon C.; d’Apice, Anthony J.F.

    2011-01-01

    Purpose of review Deletion of the α1,3-galactosyltransferase (GalT) gene in pigs has removed a major xenoantigen but has not eliminated the problem of dysregulated coagulation and vascular injury. Rejecting GalT KO organ xenografts almost invariably show evidence of thrombosis and platelet sequestration, and primate recipients frequently develop consumptive coagulopathy (CC). This review examines recent findings that illuminate potential mechanisms of this current barrier to successful xenotransplantation. Recent findings The coagulation response to xenotransplantation differs depending on the type of organ and quite likely the distinct vasculatures. Renal xenografts appear more likely to initiate CC than cardiac xenografts, possibly reflecting differential transcriptional responses. Liver xenografts induce rapid and profound thrombocytopenia resulting in recipient death within days due to bleeding; ex vivo data suggest that liver endothelial cells and hepatocytes are responsible for platelet consumption by a coagulation-independent process. It has been proposed that expression of recipient tissue factor on platelets and monocytes is an important trigger of CC. Finally, pigs transgenic for human anticoagulants and antithrombotics are slowly but surely coming on line, but have not yet been rigorously tested to date. Summary Successful control of coagulation dysregulation in xenotransplantation may require different combinatorial pharmacological and genetic strategies for different organs. PMID:21415824

  10. Depleted argon from underground sources

    SciTech Connect

    Back, H.O.; Alton, A.; Calaprice, F.; Galbiati, C.; Goretti, A.; Kendziora, C.; Loer, B.; Montanari, D.; Mosteiro, P.; Pordes, S.; /Fermilab

    2011-09-01

    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.

  11. Laser acceleration in argon clusters and gas media

    NASA Astrophysics Data System (ADS)

    Mirzaie, Mohammad; Hafz, Nasr A. M.; Li, Song; Gao, Kai; Li, Guangyu; ul-Ain, Qurat-; Zhang, Jie

    2016-03-01

    We experimentally investigated the generation of high-energy electron beams from laser-driven wakefield acceleration in argon gas jets by using tens of terawatt 30 fs ultrafast laser pulses that were focused to a relatively large-spot size, unmatched with the laser–plasma parameters. In this interaction, and depending on the Ar gas jet density, we could distinguish two different regimes for electron acceleration in the argon medium. In the high-density argon gas jet where argon clusters are formed, upon interaction with the laser electron beams having as high a charge as 3nC are generated. However, the energy spectra of those electron beams were continuous. On the other hand, high-quality quasi-mono-energetic electron beams with a modest charge of tens of pC are observed at much lower argon gas jet densities. The generation of such a high-quality electron beam is attributed to the ionization injection mechanism in which the electron injection takes place over only a few hundred micrometers of the laser–plasma interaction length, leading to the generation of high-quality electron beams.

  12. Coagulation factor XII protease domain crystal structure

    PubMed Central

    Pathak, M; Wilmann, P; Awford, J; Li, C; Hamad, BK; Fischer, PM; Dreveny, I; Dekker, LV; Emsley, J

    2015-01-01

    Background Coagulation factor XII is a serine protease that is important for kinin generation and blood coagulation, cleaving the substrates plasma kallikrein and FXI. Objective To investigate FXII zymogen activation and substrate recognition by determining the crystal structure of the FXII protease domain. Methods and results A series of recombinant FXII protease constructs were characterized by measurement of cleavage of chromogenic peptide and plasma kallikrein protein substrates. This revealed that the FXII protease construct spanning the light chain has unexpectedly weak proteolytic activity compared to β-FXIIa, which has an additional nine amino acid remnant of the heavy chain present. Consistent with these data, the crystal structure of the light chain protease reveals a zymogen conformation for active site residues Gly193 and Ser195, where the oxyanion hole is absent. The Asp194 side chain salt bridge to Arg73 constitutes an atypical conformation of the 70-loop. In one crystal form, the S1 pocket loops are partially flexible, which is typical of a zymogen. In a second crystal form of the deglycosylated light chain, the S1 pocket loops are ordered, and a short α-helix in the 180-loop of the structure results in an enlarged and distorted S1 pocket with a buried conformation of Asp189, which is critical for P1 Arg substrate recognition. The FXII structures define patches of negative charge surrounding the active site cleft that may be critical for interactions with inhibitors and substrates. Conclusions These data provide the first structural basis for understanding FXII substrate recognition and zymogen activation. PMID:25604127

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

    SciTech Connect

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

    1986-01-01

    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.

  14. Electrical conductivity of compressed argon

    SciTech Connect

    Bauer, R.; Windl, W.; Collins, L.; Kress, J.; Kwon, I.

    1997-10-01

    The authors report calculations of the electrical conductivity of solid argon as a function of compression within the density functional local density approximation formulation for a norm-conserving pseudopotential using both electron-phonon coupling and molecular dynamics techniques.

  15. The Liquid Argon Purity Demonstrator

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  16. Electron Impact Induced VUV Emission from Argon

    NASA Astrophysics Data System (ADS)

    Young, J. A.; Malone, C. P.; Johnson, P. V.

    2011-10-01

    Emission intensity and spectra are important tools for diagnosing plasma properties such as electron temperature and neutral density. In order to properly interpret emissions from low-density plasmas, accurate cross sections are needed, particularly low energy electron-impact cross sections. Of interest are the cross sections for Argon, a common species used in industrial and lighting applications. In this paper, we present recent measurements of electron-impact induced VUV emissions from Ar using a magnetically collimated monoenergetic beam of electrons and a 0.2m spectrometer. Specifically, we present emission excitation functions for both Ar I(1048 ) and Ar I(1066 ) emissions. Similarities and differences between current results and previously published emission results will be discussed. Also discussed will be the relation to recent electron energy loss results.

  17. Study of fluid mechanical helium argon ion laser

    NASA Technical Reports Server (NTRS)

    1972-01-01

    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.

  18. Coagulation Changes During Graded Orhostatic Stress and Recovery

    NASA Astrophysics Data System (ADS)

    Goswami, Nandu; Cvirn, Gerhard; Schlagenhauf, Aaxel; Leschnik, Bettina; Koestenberger, Martin; Roessler, Andreas; Jantscher, Andreas; Waha, James Elvis; Wolf, Sabine; Vrecko, Karoline; Juergens, Guenther; Hinghofer-Szalkay, Helmut

    2013-02-01

    Background: Orthostatic stress has been introduced as a novel paradigm for activating the coagulation system. We examined whether graded orthostatic stress (using head up tilt, HUT + lower body negative pressure, LBNP) until presyncope leads to anti / pro-coagulatory changes and how rapidly they return to baseline during recovery. Methodology: Eight male subjects were enrolled in this study. Presyncopal runs were carried out using HUT + LBNP. At minute zero, the tilt table was brought from 0 (supine) to 70 head-up position for 4 min, after which pressure in the LBNP chamber was reduced to -15, -30, and -45 mm Hg every 4 min. At presyncope, the subjects were returned to supine position. Coagulatory responses and plasma mass density (for volume changes) were measured before, during and 20 min after the orthostatic stress. Whole blood coagulation was examined by means of thrombelastometry. Platelet aggregation in whole blood was examined by using impedance aggregometry. Thrombin generation parameters, prothrombin levels, and markers of endothelial activation were measured in plasma samples. Results: At presyncope, plasma volume was 20 % below the initial supine value. Blood cell counts, prothrombin levels, thrombin peak, endogenous thrombin potential (ETP), and tissue factor pathway inhibitor (TFPI) levels increased during the protocol, commensurate with hemoconcentration. The markers of endothelial activation (tissue factor, TF, tissue plasminogen activator, t-PA) and the markers of thrombin generation (Prothrombin fragments 1 and 2, F1+2, and thrombin-antithrombin complex, TAT) increased significantly. During recovery, all the coagulation parameters returned to initial supine values except F1 +2 and TAT. Conclusion: Head-up tilt/LBNP leads to activation of the coagulation system. Some of the markers of thrombin formation are still at higher than supine levels during recovery.

  19. Interacting processes in protein coagulation.

    PubMed

    San Biagio, P L; Martorana, V; Emanuele, A; Vaiana, S M; Manno, M; Bulone, D; Palma-Vittorelli, M B; Palma, M U

    1999-10-01

    A strong interest is currently focused on protein self-association and deposit. This usually involves conformational changes of the entire protein or of a fragment. It can occur even at low concentrations and is responsible for pathologies such as systemic amyloidosis, Alzheimer's and Prion diseases, and other neurodegenerative pathologies. Readily available proteins, exhibiting at low concentration self-association properties related to conformational changes, offer very convenient model systems capable of providing insight into this class of problems. Here we report experiments on bovine serum albumin, showing that the process of conformational change of this protein towards an intermediate form required for coagulation occurs simultaneously and interacts with two more processes: mesoscopic demixing of the solution and protein cross-linking. This pathway of three interacting processes allows coagulation even at very low concentrations, and it has been recently observed also in the case of a nonpeptidic polymer. It could therefore be a fairly common feature in polymer coagulation/gelation. Proteins 1999;37:116-120. PMID:10451555

  20. Spatial Propagation and Localization of Blood Coagulation Are Regulated by Intrinsic and Protein C Pathways, Respectively

    PubMed Central

    Panteleev, Mikhail A.; Ovanesov, Mikhail V.; Kireev, Dmitrii A.; Shibeko, Aleksei M.; Sinauridze, Elena I.; Ananyeva, Natalya M.; Butylin, Andrey A.; Saenko, Evgueni L.; Ataullakhanov, Fazoil I.

    2006-01-01

    Blood coagulation in vivo is a spatially nonuniform, multistage process: coagulation factors from plasma bind to tissue factor (TF)-expressing cells, become activated, dissociate, and diffuse into plasma to form enzymatic complexes on the membranes of activated platelets. We studied spatial regulation of coagulation using two approaches: 1), an in vitro experimental model of clot formation in a thin layer of plasma activated by a monolayer of TF-expressing cells; and 2), a computer simulation model. Clotting in factor VIII- and factor XI-deficient plasmas was initiated normally, but further clot elongation was impaired in factor VIII- and, at later stages, in factor XI-deficient plasma. The data indicated that clot elongation was regulated by factor Xa formation by intrinsic tenase, whereas factor IXa was formed by extrinsic tenase on activating cells and diffused into plasma, thus sustaining clot growth. Far from the activating cells, additional factor IXa was produced by factor XIa. Exogenously added TF had no effect on the clot growth rate, suggesting that plasma TF does not contribute significantly to the clot propagation process in a reaction-diffusion system without flow. Addition of thrombomodulin at 3100 nM caused dose-dependent termination of clot elongation with a final clot size of 20.2 mm. These results identify roles of specific coagulation pathways at different stages of spatial clot formation (initiation, elongation, and termination) and provide a possible basis for their therapeutic targeting. PMID:16326897

  1. Acquired coagulant factor VIII deficiency induced by Bacillus anthracis lethal toxin in mice.

    PubMed

    Sun, Der-Shan; Lee, Po-Chien; Kau, Jyh-Hwa; Shih, Yung-Luen; Huang, Hsin-Hsien; Li, Chen-Ru; Lee, Chin-Cheng; Wu, Yu-Ping; Chen, Kuo-Ching; Chang, Hsin-Hou

    2015-01-01

    Mice treated with anthrax lethal toxin (LT) exhibit hemorrhage caused by unknown mechanisms. Moreover, LT treatment in mice induced liver damage. In this study, we hypothesized that a suppressed coagulation function may be associated with liver damage, because the liver is the major producing source of coagulation factors. The hepatic expression of coagulant factors and the survival rates were analyzed after cultured cells or mice were exposed to LT. In agreement with our hypothesis, LT induces cytotoxicity against hepatic cells in vitro. In addition, suppressed expression of coagulation factor VIII (FVIII) in the liver is associated with a prolonged plasma clotting time in LT-treated mice, suggesting a suppressive role of LT in coagulation. Accordingly, we further hypothesized that a loss-of-function approach involving treatments of an anticoagulant should exacerbate LT-induced abnormalities, whereas a gain-of-function approach involving injections of recombinant FVIII to complement the coagulation deficiency should ameliorate the pathogenesis. As expected, a sublethal dose of LT caused mortality in the mice that were non-lethally pretreated with an anticoagulant (warfarin). By contrast, treatments of recombinant FVIII reduced the mortality from a lethal dose of LT in mice. Our results indicated that LT-induced deficiency of FVIII is involved in LT-mediated pathogenesis. Using recombinant FVIII to correct the coagulant defect may enable developing a new strategy to treat anthrax. PMID:25906166

  2. Void dynamics in low-pressure acetylene RF plasmas

    NASA Astrophysics Data System (ADS)

    van de Wetering, Ferdinandus Martinus Jozef Henricus; Nijdam, Sander; Beckers, Job; Kroesen, Gerardus Maria Wilhelmus

    2013-09-01

    In low-pressure acetylene plasmas, dust particles spontaneously form under certain conditions. This process occurs in a matter of seconds to minutes after igniting the plasma and results in a cloud of particulates up to micrometer sizes levitated in the plasma. We studied a capacitively coupled radio-frequency plasma under normal gravity conditions and constant flow of feed gas (argon and acetylene). After the dust cloud has been formed, an ellipsoid-shaped dust-free zone - called a void - develops and grows as a function of time. Concurrently, the dust particles grow in size. Peculiar dynamics of the void have been observed, where during its expansions it suddenly stops growing and even shrinks, to shortly thereafter resume its expansion. We infer this is induced by coagulation of a new batch of dust particles inside the void. The whole dust growth and void expansion/contraction is periodical and highly reproducible. Several techniques are used to gain information about the plasma dynamics. Microwave cavity resonance spectroscopy is used to determine the global electron density. Scattering of a vertical laser sheet is used to visualize the dust particle density. The electrical characteristics of the plasma are determined using a commercially available plasma impedance monitor. This work is supported by NanoNextNL, a micro and nanotechnology programme of the Dutch Government and 130 partners.

  3. Thrombin-Responsive Gated Silica Mesoporous Nanoparticles As Coagulation Regulators.

    PubMed

    Bhat, Ravishankar; Ribes, ngela; Mas, Nria; Aznar, Elena; Sancenn, Flix; Marcos, M Dolores; Murgua, Jose R; Venkataraman, Abbaraju; Martnez-Mez, Ramn

    2016-02-01

    The possibility of achieving sophisticated actions in complex biological environments using gated nanoparticles is an exciting prospect with much potential. We herein describe new gated mesoporous silica nanoparticles (MSN) loaded with an anticoagulant drug and capped with a peptide containing a thrombin-specific cleavage site. When the coagulation cascade was triggered, active thrombin degraded the capping peptidic sequence and induced the release of anticoagulant drugs to delay the clotting process. The thrombin-dependent response was assessed and a significant increase in coagulation time in plasma from 2.6 min to 5 min was found. This work broadens the application of gated silica nanoparticles and demonstrates their ability to act as controllers in a complex scenario such as hemostasis. PMID:26794474

  4. Axial evolution of radial heat flux profiles transmitted by atmospheric pressure nitrogen and argon arcs

    NASA Astrophysics Data System (ADS)

    Meher, K. C.; Tiwari, N.; Ghorui, S.; Sahasrabudhe, S. N.; Das, A. K.

    2014-12-01

    Axial evolutions of radial heat flux profiles in argon and nitrogen plasma jets from an atmospheric pressure dc non-transferred arc plasma torch are determined using a double calorimetric technique. Results are presented for power levels suitable for the processing of high temperature ceramic oxides, where the heat flux data reported in the literature is rare. Variations of the profile widths and profile maxima are presented as a function of axial distance as well as power. Relatively uniform profile width over prolonged axial distance for nitrogen plasma compared to argon is an important observation which has the potential to offer a much longer dwell time of the injected particles inside the plasma, avoiding the problem of unmelts, especially for ceramics. A comparative study of the heat flux profiles for argon and nitrogen plasma is presented. The obtained results are compared with the data reported in literature.

  5. Sonoluminescing Air Bubbles Rectify Argon

    SciTech Connect

    Lohse, D.; Hilgenfeldt, S.; Brenner, M.P.; Dupont, T.F.; Johnston, B.

    1997-02-01

    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}

  6. [Effect of soluble fibrin on the blood coagulation process and platelets aggregation].

    PubMed

    Zaichko, N V; Chernyshenko, T M; Platonova, T M; Volkov, H L

    2006-01-01

    The accumulation of soluble fibrin (SF) in the blood plasma causes acceleration of the final stage of blood coagulation. It increases functional activity of a hemostasis system platelet link, that is the precondition of thrombotic complication. Accumulation of SF in the blood plasma is accompanied by proportional reduction of coagulation time in ancistron and thrombin time tests, and also the intensification of platelets aggregation process. A conclusion was drawn that for early diagnostics of the DIC-syndrom it is expedient to carry out complex estimation of the hemostasis system with obligatory definition of the blood SF content, performance of ancistron and thrombin time tests, and also study of platelets aggregation. PMID:17100319

  7. Effect of fibrinogen on blood coagulation detected by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Xu, Xiangqun; Teng, Xiangshuai

    2015-05-01

    Our previous work demonstrated that an optical coherence tomography (OCT) technique and the parameter 1/e light penetration depth (d1/e) were able to characterize the whole blood coagulation process in contrast to existing optical tests that are performed on plasma samples. To evaluate the feasibility of the technique for quantifying the effect of fibrinogen (Fbg) on blood coagulation, a dynamic study of d1/e of blood in various Fbg concentrations was performed in static state. Two groups of blood samples of hematocrit (HCT) in 35, 45, and 55% were reconstituted of red blood cells with: 1) treated plasma with its intrinsic Fbg removed and commercial Fbg added (0-8 g L-1) and 2) native plasma with commercial Fbg added (0-8 g L-1). The results revealed a typical behavior due to coagulation induced by calcium ions and the clotting time is Fbg concentration-dependent. The clotting time was decreased by the increasing amount of Fbg in both groups. Besides, the blood of lower HCT with various levels of Fbg took shorter time to coagulate than that of higher HCT. Consequently, the OCT method is a useful and promising tool for the detection of blood-coagulation processes induced with different Fbg levels.

  8. Geminate recombination in liquid argon

    NASA Astrophysics Data System (ADS)

    Freeman, Gordon R.

    1984-04-01

    The extended Onsager model for geminate neutralization is supported by the field dependence of the ionization yield in liquid argon irradiated by high energy electrons or x rays. Attempts to employ the model fail unless the distribution of initial separation distances between the thermalized electrons and their sibling ions (secondary electron thermalization ranges) is included. Data of Scalettar and co-workers are reanalyzed.

  9. Textile wastewater purification through natural coagulants

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  10. Blood coagulation reactions on nanoscale membrane surfaces

    NASA Astrophysics Data System (ADS)

    Pureza, Vincent S.

    Blood coagulation requires the assembly of several membrane-bound protein complexes composed of regulatory and catalytic subunits. The biomembranes involved in these reactions not only provide a platform for these procoagulant proteins, but can also affect their function. Increased exposure of acidic phospholipids on the outer leaflet of the plasma membrane can dramatically modulate the catalytic efficiencies of such membrane-bound enzymes. Under physiologic conditions, however, these phospholipids spontaneously cluster into a patchwork of membrane microdomains upon which membrane binding proteins may preferentially assemble. As a result, the membrane composition surrounding these proteins is largely unknown. Through the development and use of a nanometer-scale bilayer system that provides rigorous control of the phospholipid membrane environment, I investigated the role of phosphatidylserine, an acidic phospholipid, in the direct vicinity (within nanometers) of two critical membrane-bound procoagulant protein complexes and their respective natural substrates. Here, I present how the assembly and function of the tissue factor˙factor VIIa and factor Va˙factor Xa complexes, the first and final cofactor˙enzyme complexes of the blood clotting cascade, respectively, are mediated by changes in their immediate phospholipid environments.

  11. Silica Nanoparticles Effects on Blood Coagulation Proteins and Platelets

    PubMed Central

    Gryshchuk, Volodymyr; Galagan, Natalya

    2016-01-01

    Interaction of nanoparticles with the blood coagulation is important prior to their using as the drug carriers or therapeutic agents. The aim of present work was studying of the primary effects of silica nanoparticles (SiNPs) on haemostasis in vitro. We studied the effect of SiNPs on blood coagulation directly estimating the activation of prothrombin and factor X and to verify any possible effect of SiNPs on human platelets. It was shown that SiNPs shortened coagulation time in APTT and PT tests and increased the activation of factor X induced by RVV possibly due to the sorption of intrinsic pathway factors on their surface. SiNPs inhibited the aggregation of platelet rich plasma induced by ADP but in the same time partially activated platelets as it was shown using flow cytometry. The possibility of SiNPs usage in nanomedicine is strongly dependant on their final concentration in bloodstream and the size of the particles that are used. However SiNPs are extremely promising as the haemostatic agents for preventing the blood loss after damage. PMID:26881078

  12. Abnormal factor VIII coagulant antigen in patients with renal dysfunction and in those with disseminated intravascular coagulation.

    PubMed Central

    Weinstein, M J; Chute, L E; Schmitt, G W; Hamburger, R H; Bauer, K A; Troll, J H; Janson, P; Deykin, D

    1985-01-01

    Factor VIII antigen (VIII:CAg) exhibits molecular weight heterogeneity in normal plasma. We have compared the relative quantities of VIII:CAg forms present in normal individuals (n = 22) with VIII:CAg forms in renal dysfunction patients (n = 19) and in patients with disseminated intravascular coagulation (DIC; n = 7). In normal plasma, the predominant VIII: CAg form, detectable by sodium dodecyl sulfate polyacrylamide gel electrophoresis, was of molecular weight 2.4 X 10(5), with minor forms ranging from 8 X 10(4) to 2.6 X 10(5) D. A high proportion of VIII:CAg in renal dysfunction patients, in contrast, was of 1 X 10(5) mol wt. The patients' high 1 X 10(5) mol wt VIII: CAg level correlated with increased concentrations of serum creatinine, F1+2 (a polypeptide released upon prothrombin activation), and with von Willebrand factor. Despite the high proportion of the 1 X 10(5) mol wt VIII:CAg form, which suggests VIII:CAg proteolysis, the ratio of Factor VIII coagulant activity to total VIII:CAg concentration was normal in renal dysfunction patients. These results could be simulated in vitro by thrombin treatment of normal plasma, which yielded similar VIII:CAg gel patterns and Factor VIII coagulant activity to antigen ratios. DIC patients with high F1+2 levels but no evidence of renal dysfunction had an VIII:CAg gel pattern distinct from renal dysfunction patients. DIC patients had elevated concentrations of both the 1 X 10(5) and 8 X 10(4) mol wt VIII:CAg forms. We conclude that an increase in a particular VIII:CAg form correlates with the severity of renal dysfunction. The antigen abnormality may be the result of VIII:CAg proteolysis by a thrombinlike enzyme and/or prolonged retention of proteolyzed VIII:CAg fragments. Images PMID:3932466

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

    PubMed

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

    2015-01-01

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

  14. Argon laser treatment for trichiasis.

    PubMed

    Huneke, J W

    1992-01-01

    The goal of trichiasis treatment is to eliminate misdirected cilia that irritate the eyeball. Established methods for removal of the eyelashes include epilation, electrolysis, and cryotherapy. Cryotherapy is currently the most effective method in widespread use, but has as potential posttreatment complications "visual loss, lid notching, corneal ulcer, acceleration of symblepharon formation, xerosis, cellulitis, activation of herpes zoster, skin depigmentation, and severe soft tissue reaction." (Wood JR, Anderson RL. Complications of cryosurgery. Arch Ophthalmol 1981;99:460-3.) The use of an argon laser allows more precise placement and control of the treatment, with better overall results. We reviewed the clinical course of 77 patients with a diagnosis of trichiasis, and 1 with distichiasis. We have found treatment of trichiasis with an argon laser with the patient under local anesthesia to be an effective office procedure. PMID:1554654

  15. Transfusion and coagulation management in liver transplantation

    PubMed Central

    Clevenger, Ben; Mallett, Susan V

    2014-01-01

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

  16. The singular coagulation equation with multiple fragmentation

    NASA Astrophysics Data System (ADS)

    Saha, Jitraj; Kumar, Jitendra

    2015-06-01

    In this paper, we prove the global existence and uniqueness of the solutions to the initial-value problem for the coagulation-fragmentation equation with singular coagulation kernel and multiple fragmentation kernel. The solution obtained in this case also satisfies the mass conservation law. The proof is based on strong convergence methods applied to suitably chosen unbounded coagulation kernels having singularities in both the coordinate axes and satisfying certain growth conditions, which can possibly reach up to a quadratic growth at infinity, and the fragmentation kernel covers a very large class of unbounded functions.

  17. Argon and argon-oxygen glow discharge cleaning of the Main Ring beam pipe

    SciTech Connect

    Trbojevic, D.; Pastore, N.

    1989-02-15

    This report presents the experimental results from the argon and argon-oxygen gas mixture glow discharge in the Main Ring beam pipe and is a follow-up to the proposal for vacuum improvements of the Main Ring magnets and straight sections and the warm Tevatron straight sections. Glow discharge was used in the experiment in order to clean the vacuum system instead of bakeout which could only be performed with great difficulty or not at all. It is a relatively simple and very effective method. The glow discharge occurs under specific gas pressures (10--120 mTorr) and current flows (10/sup /minus/5/ /minus/ 10/sup /minus/1/ A) through gas excitation and formation of plasma conditions. Deexcitation of the gas molecules produces visible light. Several mechanisms have been proposed to explain the glow discharge cleaning process. Ions can sputter adsorbed molecules or atoms at the cathode surface and even produce lattice damage extending several monolayers below the surface. The glow discharge has already been extensively used for vacuum improvements in accelerators. 9 refs.

  18. Determination of the rate coefficient of the electron-impact excitation from the argon resonance states (1s2 and 1s4) to 2p states by the emission line ratio in an afterglow plasma

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi-Wen; Zhu, Xi-Ming; Liu, Fei-Xiang; Pu, Yi-Kang

    2015-04-01

    The rate coefficients of electron-impact excitation from argon 1s2 and 1s4 (resonance states) to 2p states are determined in the electron temperature (Te) range of 0.5-1.1 eV. This is achieved by using a population model for Ar(2p) and measured parameters in the afterglow of an rf (60 MHz) pulsed capacitive discharge. These parameters include the densities of the 2p states (optical emission spectroscopy), the densities of the four argon 1s states (diode laser absorption), and Te (a Langmuir probe and a line-ratio technique), for discharges with two gas mixtures: Ar(60 mTorr)/O2(2 mTorr) and Ar(60 mTorr)/Xe(1.8 mTorr). It is found that the rate coefficients obtained in this work agree well with those from the cross sections by a large-scale R-matrix calculation reported recently by Zatsarinny et al (2004 J. Phys. B: At. Mol. Opt. Phys. 37 4693, 2014 Phys. Rev. A 89 022706).

  19. Vacuum ultraviolet argon excimer laser excited by optical-field-induced ionized electrons produced in an argon-filled hollow fiber

    NASA Astrophysics Data System (ADS)

    Kubodera, Shoichi; Kaku, Masanori; Katto, Masahito

    2011-10-01

    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 demonstrated the production of argon excimers via an optical-field-induced ionization (OFI) process by using a high-intensity infrared laser. We here report optical amplification of argon excimers at the wavelength of 126 nm by producing an extended OFI plasma inside an argon-filled hollow fiber with an inner diameter of 250 microns with a length of 5.0 cm. A gain-length product of 4.3 through the use of single-pass amplification with VUV optics was observed, indicating a small signal gain coefficient of 0.86 cm-1 with an uncertainty of 0.03. It was found that the hollow fiber served to extend the OFI plasma length and to guide the excitation of the infrared laser and the produced VUV emissions at 126 nm, but did not affect the OFI plasma conditions to produce argon excimer molecules. 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 demonstrated the production of argon excimers via an optical-field-induced ionization (OFI) process by using a high-intensity infrared laser. We here report optical amplification of argon excimers at the wavelength of 126 nm by producing an extended OFI plasma inside an argon-filled hollow fiber with an inner diameter of 250 microns with a length of 5.0 cm. A gain-length product of 4.3 through the use of single-pass amplification with VUV optics was observed, indicating a small signal gain coefficient of 0.86 cm-1 with an uncertainty of 0.03. It was found that the hollow fiber served to extend the OFI plasma length and to guide the excitation of the infrared laser and the produced VUV emissions at 126 nm, but did not affect the OFI plasma conditions to produce argon excimer molecules. Part of this work has been supported by Hamamatsu Photonics K. K., Japan.

  20. ARSENIC REMOVAL BY SOFTENING AND COAGULATION

    EPA Science Inventory

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

  1. Coagulation testing in the perioperative period

    PubMed Central

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

    2014-01-01

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

  2. Effects of Al-coagulant sludge characteristics on the efficiency of coagulants recovery by acidification.

    PubMed

    Chen, Yi-Jui; Wang, Wen-May; Wei, Ming-Jun; Chen, Jiann-Long; He, Ju-Liang; Chiang, Kung-Yuh; Wu, Chih-Chao

    2012-12-01

    This study evaluated the effects of Al-coagulant sludge characteristics on the efficiency ofcoagulant recovery by acidification with H2SO4. Two sludge characteristics were studied: types of coagulant and textures of the suspended solid in raw water. The coagulant types are aluminium sulphate and polyaluminium chloride (PACl); the textures of the suspended solid are sand-based and clay-based. Efficiency of aluminium recovery at a pH of 2 was compared for different sludges obtained from water treatment plants in Taiwan. The results showed that efficiency of aluminium recovery from sludge containing clayey particles was higher than that from sludge containing sandy particles. As for the effect of coagulant types, the aluminium recovery efficiency for sludge using PACl ranged between 77% and 100%, whereas it ranged between 65% and 72% for sludge using aluminium sulphate as the coagulant. This means using PACl as the coagulant could result in higher recovery efficiency of coagulant and be beneficial for water treatment plants where renewable materials and waste reduction as the factors for making decisions regarding plant operations. However, other metals, such as manganese, could be released with aluminium during the acidification process and limit the use of the recovered coagulants. It is suggested that the recovered coagulants be used in wastewater treatment processes. PMID:23437650

  3. Coagulation algorithms with size binning

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  4. Emergent self-similarity of cluster coagulation

    NASA Astrophysics Data System (ADS)

    Pushkin, Dmtiri O.

    A wide variety of nonequilibrium processes, such as coagulation of colloidal particles, aggregation of bacteria into colonies, coalescence of rain drops, bond formation between polymerization sites, and formation of planetesimals, fall under the rubric of cluster coagulation. We predict emergence of self-similar behavior in such systems when they are 'forced' by an external source of the smallest particles. The corresponding self-similar coagulation spectra prove to be power laws. Starting from the classical Smoluchowski coagulation equation, we identify the conditions required for emergence of self-similarity and show that the power-law exponent value for a particular coagulation mechanism depends on the homogeneity index of the corresponding coagulation kernel only. Next, we consider the current wave of mergers of large American banks as an 'unorthodox' application of coagulation theory. We predict that the bank size distribution has propensity to become a power law, and verify our prediction in a statistical study of the available economical data. We conclude this chapter by discussing economically significant phenomenon of capital condensation and predicting emergence of power-law distributions in other economical and social data. Finally, we turn to apparent semblance between cluster coagulation and turbulence and conclude that it is not accidental: both of these processes are instances of nonlinear cascades. This class of processes also includes river network formation models, certain force-chain models in granular mechanics, fragmentation due to collisional cascades, percolation, and growing random networks. We characterize a particular cascade by three indicies and show that the resulting power-law spectrum exponent depends on the indicies values only. The ensuing algebraic formula is remarkable for its simplicity.

  5. Removal of silver nanoparticles by coagulation processes.

    PubMed

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

    2013-10-15

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

  6. Dust Coagulation in Protoplanetary Accretion Disks

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  7. [Incidental finding of pathological coagulation parameters].

    PubMed

    Luxembourg, B; Lindhoff-Last, E

    2014-10-01

    Pathological coagulation parameters may reflect life-threatening hemorrhagic or thromboembolic diseases but may also be a laboratory result without any clinical significance, result from in vitro phenomena or preanalytical errors. This article gives an overview of potential pitfalls in coagulation diagnostics, lists the differential diagnoses of pathological coagulation parameters and describes further steps in the diagnostic approach to clarify pathological results. The focus lies on coagulation parameters that are frequently determined in routine clinical investigations, e.g. platelet count, prothrombin time, activated partial thromboplastin time (aPTT) and fibrinogen. Besides heparin, fondaparinux, danaparoid, and vitamin K antagonists, direct factor Xa inhibitors and direct thrombin inhibitors are nowadays available for therapeutic anticoagulation. This article gives an overview of the influence of anticoagulants on coagulation parameters which depends on the dose, the time of the last administration, as well as the method used for the determination of coagulation parameters. Moreover, common reasons for elevation of the fibrin degradation product D-dimer are presented. The clinical utility of D-dimer assays is limited by their poor specificity. Elevated D-dimer concentrations can be found in various diseases and also under normal physiological circumstances (e.g. in the elderly). Thus, the most useful clinical application of D-dimer is evidence of normal values to essentially rule out venous thromboembolism. PMID:25190093

  8. Liquid Argon Calorimetry for ATLAS

    NASA Astrophysics Data System (ADS)

    Robinson, Alan

    2008-05-01

    This summer, the largest collaborative physics project since the Manhattan project will go online. One of four experiments for the Large Hadron Collider at CERN in Geneva, ATLAS, employs over 2000 people. Canadians have helped design, construct, and calibrate the liquid argon calorimeters for ATLAS to capture the products of the high energy collisions produced by the LHC. From an undergraduate's perspective, explore how these calorimeters are made to handle their harsh requirement. From nearly a billion proton-proton collisions a second, physicists hope to discover the Higgs boson and other new fundamental particles.

  9. A DSMC Study of Low Pressure Argon Discharge

    NASA Technical Reports Server (NTRS)

    Hash, David B.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    Work toward a self-consistent plasma simulation using the DSMC (Direct Simulation Monte Carlo) method for examination of the flowfields of low-pressure high density plasma reactors is presented. Presently, DSMC simulations for these applications involve either treating the electrons as a fluid or imposing experimentally determined values for the electron number density profile. In either approach, the electrons themselves are not physically simulated. Self-consistent plasma DSMC simulations have been conducted for aerospace applications but at a severe computational cost due in part to the scalar architectures on which the codes were employed. The present work attempts to conduct such simulations at a more reasonable cost using a plasma version of the object-oriented parallel Cornell DSMC code, MONACO, on an IBM SP-2. Due to availability of experimental data, the GEC reference cell is chosen to conduct preliminary investigations. An argon discharge is chosen to conduct preliminary investigations. An argon discharge is examined thus affording a simple chemistry set with eight gas-phase reactions and five species: Ar, Ar(+), Ar(*), Ar(sub 2), and e where Ar(*) is a metastable.

  10. Boltzmann expansion in a radiofrequency conical helicon thruster operating in xenon and argon

    NASA Astrophysics Data System (ADS)

    Charles, C.; Boswell, R.; Takahashi, K.

    2013-06-01

    A low pressure (0.5 mTorr in xenon and 1 mTorr in argon) Boltzmann expansion is experimentally observed on axis within a magnetized (60 to 180 G) radiofrequency (13.56 MHz) conical helicon thruster for input powers up to 900 W using plasma parameters measured with a Langmuir probe. The axial forces, respectively, resulting from the electron and magnetic field pressures are directly measured using a thrust balance for constant maximum plasma pressure and show a higher fuel efficiency for argon compared to xenon.

  11. Boltzmann expansion in a radiofrequency conical helicon thruster operating in xenon and argon

    SciTech Connect

    Charles, C.; Boswell, R.; Takahashi, K.; Department of Electrical Engineering, Tohoku University, Sendai 980-9579

    2013-06-03

    A low pressure ({approx}0.5 mTorr in xenon and {approx}1 mTorr in argon) Boltzmann expansion is experimentally observed on axis within a magnetized (60 to 180 G) radiofrequency (13.56 MHz) conical helicon thruster for input powers up to 900 W using plasma parameters measured with a Langmuir probe. The axial forces, respectively, resulting from the electron and magnetic field pressures are directly measured using a thrust balance for constant maximum plasma pressure and show a higher fuel efficiency for argon compared to xenon.

  12. Argon K? measurement on DIII-D by Ross filters technique (abstract)

    NASA Astrophysics Data System (ADS)

    Snider, R. T.; Bogatu, I. N.; Brooks, N. H.; Wade, M. R.

    1999-01-01

    Techniques to reduce the heat flux to the divertor plates in tokamak power plants and the consequent erosion of, and subsequent damage to the divertor target plates include the injection of impurities such as argon, that can dissipate the energy (through radiative or collisional processes) before it reaches the target plates. An important issue with this type of scheme is poisoning of the plasma core by the impurities introduced in the divertor region. Subsequently, there is a desire to measure the profiles of the injected impurities in the core. X-ray Ross filters with an effective narrow band pass centered on the argon K? line at 3.2 keV, have been installed on two of the existing x-ray arrays on DIII-D in order to help determine the argon concentration profiles. Emissivity profiles of the K? lines and the emissivity profiles for the argon enhanced continuum can be inferred from the inverted filtered x-ray brightness signals if Te, ne, and Ar18+ profiles are known. The MISTReference 1 code is used to couple the filtered x-ray signals to the time dependent measurements of Te and ne. Further, the Ar16+ profiles measured by charge transfer spectroscopy, are used as a constraint on the MIST code runs to calculate Ar18+ profiles and unfold the argon emissivity profiles. A discussion of the Ross filters, the DIII-D argon data, and the data analysis scheme for inferring argon emissivity profiles will be discussed. Estimates of the total argon concentration in the core determined from this technique in DIII-D argon puff experiments will be presented.

  13. Endosulfan activates the extrinsic coagulation pathway by inducing endothelial cell injury in rats.

    PubMed

    Zhang, Lianshuang; Wei, Jialiu; Guo, Fangzi; Duan, Junchao; Li, Yanbo; Shi, Zhixiong; Yang, Yumei; Zhou, Xianqing; Sun, Zhiwei

    2015-10-01

    Endosulfan, a persistent organic pollutant, is widely used in agriculture as a pesticide. The aim of the present study was to evaluate the blood toxicity of different doses of endosulfan in Wistar rats. The experimental sample was composed of four groups, a control group that did not receive endosulfan and three endosulfan-exposed groups that respectively received 1, 5, or 10 mg/kg/day (doses below LD50), of endosulfan for 21 days. The results showed that endosulfan significantly decreased the prothrombin time (PT) and upregulated the activated coagulation factors VIIa, Xa, and XIIIa; thrombin-antithrombin complex (TAT); and P-selectin. Plasma levels of tissue factor (TF) and malondialdehyde (MDA) were increased in the endosulfan groups. The activated partial thromboplastin time (APTT) and the level of activated coagulation factor IXa showed no obvious changes. Immunohistochemical results showed increased expression of von Willebrand factor (vWF) and the inflammatory cytokine interleukin (IL)-1? in the groups exposed to endosulfan. The pathology and electron microscopy results showed impaired vascular tissue accompanied by the exfoliation of endothelial cells and mitochondrial damage in the endosulfan-exposed groups. In summary, our results suggest that endosulfan damages endothelial cells via oxidative stress and the inflammatory response, leading to the release of TF and vWF into the blood. The TF and vWF in the blood may activate extrinsic coagulation factors and platelets, thus triggering the extrinsic coagulation pathway. There were no obvious effects on the intrinsic coagulation pathway. PMID:26028348

  14. Tissue factor-dependent coagulation contributes to α-naphthylisothiocyanate-induced cholestatic liver injury in mice

    PubMed Central

    Luyendyk, James P.; Cantor, Glenn H.; Kirchhofer, Daniel; Mackman, Nigel; Copple, Bryan L.; Wang, Ruipeng

    2009-01-01

    Separation of concentrated bile acids from hepatic parenchymal cells is a key function of the bile duct epithelial cells (BDECs) that form intrahepatic bile ducts. Using coimmunostaining, we found that tissue factor (TF), the principal activator of coagulation, colocalized with cytokeratin 19, a marker of BDECs in the adult mouse liver. BDEC injury induced by xenobiotics such as α-naphthylisothiocyanate (ANIT) causes cholestasis, inflammation, and hepatocellular injury. We tested the hypothesis that acute ANIT-induced cholestatic hepatitis is associated with TF-dependent activation of coagulation and determined the role of TF in ANIT hepatotoxicity. Treatment of mice with ANIT (60 mg/kg) caused multifocal hepatic necrosis and significantly increased serum biomarkers of cholestasis and hepatic parenchymal cell injury. ANIT treatment also significantly increased liver TF expression and activity. ANIT-induced activation of the coagulation cascade was shown by increased plasma thrombin-antithrombin levels and significant deposition of fibrin within the necrotic foci. ANIT-induced coagulation and liver injury were reduced in low-TF mice, which express 1% of normal TF levels. The results indicate that ANIT-induced liver injury is accompanied by TF-dependent activation of the coagulation cascade and that TF contributes to the progression of injury during acute cholestatic hepatitis. PMID:19179621

  15. Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes

    PubMed Central

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

    2014-01-01

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

  16. Magnetic particle imaging of blood coagulation

    SciTech Connect

    Murase, Kenya Song, Ruixiao; Hiratsuka, Samu

    2014-06-23

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

  17. Magnetic particle imaging of blood coagulation

    NASA Astrophysics Data System (ADS)

    Murase, Kenya; Song, Ruixiao; Hiratsuka, Samu

    2014-06-01

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

  18. Argon purge gas cooled by chill box

    NASA Technical Reports Server (NTRS)

    Spiro, L. W.

    1966-01-01

    Cooling argon purge gas by routing it through a shop-fabricated chill box reduces charring of tungsten inert gas torch head components. The argon gas is in a cooled state as it enters the torch and prevents buildup of char caused by the high concentrations of heat in the weld area during welding operations.

  19. Collisionless "thermalization" in the sheath of an argon discharge

    NASA Astrophysics Data System (ADS)

    Coulette, David; Manfredi, Giovanni

    2015-04-01

    We performed kinetic Vlasov simulations of the plasma-wall transition for a low-pressure argon discharge without external magnetic fields, using the same plasma parameters as in the experiments of Claire et al. [Phys. Plasmas 13, 062103 (2006)]. Experimentally, it was found that the ion velocity distribution function is highly asymmetric in the presheath, but, surprisingly, becomes again close to Maxwellian inside the sheath. Here, we show that this "thermalization" can be explained by purely collisionless effects that are akin to the velocity bunching phenomenon observed in charged particles beams. Such collisionless thermalization is also observed in the presheath region close to the sheath entrance, although it is much weaker there and in practice probably swamped by collisional processes (standard or enhanced by instabilities).

  20. 2D laser-collision induced fluorescence in low-pressure argon discharges

    SciTech Connect

    Barnat, E. V.; Weatherford, B. R.

    2015-09-25

    Development and application of laser-collision induced fluorescence (LCIF) diagnostic technique is presented for the use of interrogating argon plasma discharges. Key atomic states of argon utilized for the LCIF method are identified. A simplified two-state collisional radiative model is then used to establish scaling relations between the LCIF, electron density, and reduced electric fields (E/N). The procedure used to generate, detect and calibrate the LCIF in controlled plasma environments is discussed in detail. LCIF emanating from an argon discharge is then presented for electron densities spanning 109 e cm–3 to 1012 e cm–3 and reduced electric fields spanning 0.1 Td to 40 Td. Lastly, application of the LCIF technique for measuring the spatial distribution of both electron densities and reduced electric field is demonstrated.

  1. 2D laser-collision induced fluorescence in low-pressure argon discharges

    DOE PAGESBeta

    Barnat, E. V.; Weatherford, B. R.

    2015-09-25

    Development and application of laser-collision induced fluorescence (LCIF) diagnostic technique is presented for the use of interrogating argon plasma discharges. Key atomic states of argon utilized for the LCIF method are identified. A simplified two-state collisional radiative model is then used to establish scaling relations between the LCIF, electron density, and reduced electric fields (E/N). The procedure used to generate, detect and calibrate the LCIF in controlled plasma environments is discussed in detail. LCIF emanating from an argon discharge is then presented for electron densities spanning 109 e cm–3 to 1012 e cm–3 and reduced electric fields spanning 0.1 Tdmore » to 40 Td. Lastly, application of the LCIF technique for measuring the spatial distribution of both electron densities and reduced electric field is demonstrated.« less

  2. Model of a stationary microwave argon discharge at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Zhelyazkov, I.; Pencheva, M.; Benova, E.

    2008-03-01

    The many applications of microwave gas discharges at atmospheric pressure in various fields of science, technology and medicine require an adequate model of these discharges. Such a model is based on the electromagnetic wave's propagation properties and on the elementary processes in the discharge bulk. In contrast to the microwave discharges at low-gas pressures, where many elementary processes might be ignored because of their negligible contribution to the electron and heavy particle's balance equations, for such discharges at atmospheric pressure the consideration of a large number of collisional processes is mandatory. For the build of a successful discharge-column model one needs three important quantities, notably the power ? necessary for sustaining an electronion pair, electronneutral collision frequency for momentum transfer ven, and gas temperature Tg. The first two key parameters are obtained by a collisional-radiative model of the argon at atmospheric pressure, while the microwave frequency ?/2? = 2.45 GHz, plasma column radius R, gas pressure p and gas temperature Tg are fixed external parameters determined by the experimental conditions. Here, we present a model of a capillary argon microwave plasma column with a length L ? 14 cm, sustained by wave power of 110 Wthe model yields the longitudinal distributions of the plasma density, expended wave power, wave electric field magnitude, and complex wave number.

  3. Model of a stationary microwave argon discharge at atmospheric pressure

    SciTech Connect

    Zhelyazkov, I.; Pencheva, M.; Benova, E.

    2008-03-19

    The many applications of microwave gas discharges at atmospheric pressure in various fields of science, technology and medicine require an adequate model of these discharges. Such a model is based on the electromagnetic wave's propagation properties and on the elementary processes in the discharge bulk. In contrast to the microwave discharges at low-gas pressures, where many elementary processes might be ignored because of their negligible contribution to the electron and heavy particle's balance equations, for such discharges at atmospheric pressure the consideration of a large number of collisional processes is mandatory. For the build of a successful discharge-column model one needs three important quantities, notably the power {theta} necessary for sustaining an electron - ion pair, electron - neutral collision frequency for momentum transfer v{sub en}, and gas temperature T{sub g}. The first two key parameters are obtained by a collisional-radiative model of the argon at atmospheric pressure, while the microwave frequency {omega}/2{pi} = 2.45 GHz, plasma column radius R, gas pressure p and gas temperature T{sub g} are fixed external parameters determined by the experimental conditions. Here, we present a model of a capillary argon microwave plasma column with a length L {approx_equal} 14 cm, sustained by wave power of 110 W - the model yields the longitudinal distributions of the plasma density, expended wave power, wave electric field magnitude, and complex wave number.

  4. Effect of argon ion bombardment on amorphous silicon carbonitride films

    NASA Astrophysics Data System (ADS)

    Batocki, R. G. S.; Mota, R. P.; Honda, R. Y.; Santos, D. C. R.

    2014-04-01

    Amorphous silicon carbonitride (a-SiCN:H) films were synthesized by radiofrequency (RF) Plasma Enhanced Vapor Chemical Deposition (PECVD) using hexamethyldisilazane (HMDSN) as precursor compound. Then, the films were post-treated by Plasma Immersion Ion Implantation (PIII) in argon atmosphere from 15 to 60 min. The hardness of the film enhanced after ion implantation, and the sample treated at 45 min process showed hardness greater than sixfold that of the untreated sample. This result is explained by the crosslinking and densification of the structure. Films were exposed to oxygen plasma for determining of the etching rate. It decreased monotonically from 33 /min to 19 /min for the range of process time, confirming structural alterations. Hydrophobic character of the a-SiCN:H films were modified immediately after ion bombardment, due to incorporation of polar groups. However, the high wettability of the films acquired by the ion implantation was diminished after aging in air. Therefore, argon PIII made a-SiCN:H films mechanically more resistant and altered their hydrophobic character.

  5. Modelling of Complex Plasmas

    NASA Astrophysics Data System (ADS)

    Akdim, Mohamed Reda

    2003-09-01

    Nowadays plasmas are used for various applications such as the fabrication of silicon solar cells, integrated circuits, coatings and dental cleaning. In the case of a processing plasma, e.g. for the fabrication of amorphous silicon solar cells, a mixture of silane and hydrogen gas is injected in a reactor. These gases are decomposed by making a plasma. A plasma with a low degree of ionization (typically 10_5) is usually made in a reactor containing two electrodes driven by a radio-frequency (RF) power source in the megahertz range. Under the right circumstances the radicals, neutrals and ions can react further to produce nanometer sized dust particles. The particles can stick to the surface and thereby contribute to a higher deposition rate. Another possibility is that the nanometer sized particles coagulate and form larger micron sized particles. These particles obtain a high negative charge, due to their large radius and are usually trapped in a radiofrequency plasma. The electric field present in the discharge sheaths causes the entrapment. Such plasmas are called dusty or complex plasmas. In this thesis numerical models are presented which describe dusty plasmas in reactive and nonreactive plasmas. We started first with the development of a simple one-dimensional silane fluid model where a dusty radio-frequency silane/hydrogen discharge is simulated. In the model, discharge quantities like the fluxes, densities and electric field are calculated self-consistently. A radius and an initial density profile for the spherical dust particles are given and the charge and the 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 field distribution through its charge and the density of the plasma through recombination of positive ions and electrons at its surface. In the model this process gives an extra production of silane radicals, since the growth of dust is not included. Results are presented for situations in which the dust signi_cantly changes the discharge characteristics, both by a strong reduction of the electron density and by altering the electric field by its charge. Simulations for dust with a radius of 2 mu-m show that the stationary solution of the dust density and the average electric field depend on the total amount of the dust. The presence of dust enhances the deposition rate of amorphous silicon 2 at the electrodes because of the rise in the average electron energy associated with the decrease of the electron density and the constraint of a constant power input. This increase of deposition rate has also been observed in experiments by others. To study the behavior of dust in a less complicated environment, experiments in non-reactive plasmas have been carried out by a number of research groups. In these experiments the dust particles are injected through the electrodes in an argon discharge. These experiments have shown very interesting phenomena. Dust particles start to interact with each other in the discharge and form two-dimensional Coulomb clusters. These experiments often show an appearance of a void, a dustfree region in the discharge. Similar experiments have also been carried out under microgravity. These experiments have shown three-dimensional Coulomb clusters of dust particles also with the appearance of a void. Also rotating dust clouds (vortices) near the edges of the electrodes have been observed, that tend to rotate as long as the plasmas is on. To understand the behavior of the particles, we have developed a two-dimensional fluid model for a dusty argon plasma in which the plasma and dust parameters are solved self-consistently to study the behavior of dust particles. Simulations for dust with a radius of 7.5 mu-m show that a double space charge layer is created around the sharp boundary of the dust crystal. The inter-particle interaction is taken into account by means of an equation of state for the dust. A central dust-free region (void) is created by the ion drag force. The contribution of the thermophoretic force, driven by the temperature gradient induced by gas heating from ion-neutral collisions and heating of the dust particle material by the recombining ions and electrons, can be neglected in the quasi-neutral center of the plasma. Inside this void a strong increase of the production of argon meta-stables is found. This phenomenon is in agreement with experimental observations, where an enhanced light emission is seen inside the void.

  6. Thermal damage parameters from laser coagulation experiments

    NASA Astrophysics Data System (ADS)

    Pearce, John A.; Thomsen, Sharon L.

    2003-06-01

    Estimating effective thermal damage process coefficients for the first order model of damage processes is not difficult when the temperature is held constant for a substantial period. Laser coagulation experiments, however, are of short duration and, because of non uniform beam profiles, exhibit important heat transfer effects: the thermal histories are transient by nature. We obtain the activation energy, E, and collision frequency factor, A, directly from the transient history at the boundary of the zones of white coagulation and red hemorrhagic coagulation in liver in the rat, as identified in histologic studies. The estimates are obtained by testing a large number of coefficients and determining the "best fit" from a cost function. Useful values may obtained from a single experiment if the transient history used has a very high confidence level N i.e. a few excellent curves are preferable to single curves at a large number of durations of exposure.

  7. Fibrinolysis and the control of blood coagulation

    PubMed Central

    Chapin, John C.; Hajjar, Katherine A.

    2014-01-01

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

  8. Coagulation-membrane filtration of Chlorella vulgaris.

    PubMed

    Lee, Duu-Jong; Liao, Guan-Yu; Chang, Yin-Ru; Chang, Jo-Shu

    2012-03-01

    Filtration-based separation of Chlorella vulgaris, a species with excellent potential for CO(2) capture and lipid production, was investigated using a surface-modified hydrophilic polytetrafluoroethylene (PTFE) membrane. Coagulation using polyaluminum chloride (PACl) attained maximum turbidity removal at 200 mg L(-1) as Al(2)O(3). The membrane filtration flux at 1 bar increased as the PACl dose increased, regardless of overdosing in the coagulation stage. The filtered cake at the end of filtration tests peaked in solid content at 10 mg L(-1) as Al(2)O(3), reaching 34% w/w, roughly two times that of the original suspension. Differential scanning calorimetry (DSC) tests demonstrate that the cake with minimum water-solid binding strength produced the driest filter cake. Coagulation using 10 mg L(-1) PACl as Al(2)O(3), followed by PTFE membrane filtration at 1 bar, is an effective process for harvesting C. vulgaris from algal froth. PMID:22261659

  9. Role of the extrinsic pathway of blood coagulation in hemostasis and thrombosis.

    PubMed

    Mackman, Nigel; Tilley, Rachel E; Key, Nigel S

    2007-08-01

    Hemostasis requires both platelets and the coagulation system. At sites of vessel injury, bleeding is minimized by the formation of a hemostatic plug consisting of platelets and fibrin. The traditional view of the regulation of blood coagulation is that the initiation phase is triggered by the extrinsic pathway, whereas amplification requires the intrinsic pathway. The extrinsic pathway consists of the transmembrane receptor tissue factor (TF) and plasma factor VII/VIIa (FVII/FVIIa), and the intrinsic pathway consists of plasma FXI, FIX, and FVIII. Under physiological conditions, TF is constitutively expressed by adventitial cells surrounding blood vessels and initiates clotting. In addition so-called blood-borne TF in the form of cell-derived microparticles (MPs) and TF expression within platelets suggests that TF may play a role in the amplification phase of the coagulation cascade. Under pathologic conditions, TF is expressed by monocytes, neutrophils, endothelial cells, and platelets, which results in an elevation of the levels of circulating TF-positive MPs. TF expression within the vasculature likely contributes to thrombosis in a variety of diseases. Understanding how the extrinsic pathway of blood coagulation contributes to hemostasis and thrombosis may lead to the development of safe and effective hemostatic agents and antithrombotic drugs. PMID:17556654

  10. Calculation of the shifts of argon spectral lines

    SciTech Connect

    Christova, M.; Andreev, N.; Christov, L.; Dimitrijevic, M. S.

    2008-10-22

    Shifts due to collisions with charged particles (Stark broadening ) and neutral atoms, were determined for nine argon spectral lines corresponding to the transitions 3p{sup 5}nd-3p{sup 5}4p for n = 4-7, 3p{sup 5}6s-3p{sup 5}4d and 3p{sup 5}4p'-3p{sup 5}4s in order to estimate their usability for the research and diagnostics of a plasma in a surface-wave discharge at atmospheric pressure.

  11. Determination of the rate coefficients of the electron-impact excitation from the metastable states to 2p states of argon by the emission line ratios in an afterglow plasma

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi-Wen; Zhu, Xi-Ming; Liu, Fei-Xiang; Pu, Yi-Kang

    2014-07-01

    The rate coefficients of electron-impact excitation from the argon metastable to 2p states are measured in the afterglow of an rf pulsed capacitive discharge. In the afterglow, the 2p state densities are measured by optical emission spectroscopy, the time-resolved 1s state densities are measured by laser absorption, the time-resolved electron temperature (Te) and electron density are measured by a Langmuir probe. By employing these measured parameters, the electron-impact excitation rate coefficients are obtained from the rate balance equations of 2p states in the Te range from 0.7 to 1.2 eV. The measured rate coefficients are in good agreement with those obtained from the cross sections measured by Boffard et al. In addition, we obtain rate coefficients of the transitions from the metastable states to 2p1,7,10, whose measured values have not been reported before. These rate coefficients are also compared with the calculated ones (Zatsarinny et al with the R-matrix method, Srivastava et al with the Distorted wave method).

  12. Advances in the treatment of inherited coagulation disorders.

    PubMed

    Escobar, M A

    2013-09-01

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

  13. Electrical model of an inductive ring discharge in argon

    NASA Astrophysics Data System (ADS)

    Gonzalez, J. J.; Shaw, D. M.; Watanabe, M.; Uchiyama, H.; Collins, G. J.

    2000-10-01

    Inductive ring discharges with a closed plasma loop forming the secondary circuit of a rf transformer were investigated in the 1960's as plasma sources for gas ion lasers and fusion research because of their efficiency at producing high charge density (ne 1013 cm-3). More recently, due to improvements in both ferrite core materials and rf power supply technology, ring discharges are finding application as high efficiency lighting devices and radical generators for materials processing. Herein, we analytically model an inductively coupled ring discharge over a wide range of argon pressure (mTorr to 10's of Torr) and applied rf (350 kHz) power (50 < Prf < 300 W). Only single step ionization is considered as a particle formation mechanism. For our geometry, ion free diffusion to the walls dominates charged particle loss from the ring discharge at low pressures (p < 0.1 Torr) and ion ambipolar diffusion to the walls dominates in the mid-pressure range (0.1 < p < 5 Torr). At the highest pressures investigated (5 < p < 30 Torr), three body electron-ion recombination in the bulk plasma takes over as the primary particle loss mechanism. The plasma electron density and temperature are determined from the model using measured plasma ring voltage and current. Comparisons between the modeled plasma density and Langmuir probe measurements agree to within a factor of 2 - 4 over the entire range of plasma parameters covered.

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

    PubMed

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

    2011-06-15

    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 poly-aluminum chloride (PACl) and aluminum sulfate (alum). As primary coagulant, the optimum dosage and pH for PACl were 7.2 and 7.5 g/L, respectively, with removal efficiencies of 55, 80 and 95% for COD, color and TSS, respectively. For alum, the optimum conditions were 11 g/L alum dosage and pH 6.5 with removal efficiencies of 58, 79 and 78% for COD, color and TSS, respectively. The maximum removal efficiencies of COD, color and TSS were 64, 90 and 96%, respectively, when psyllium husk was used as coagulant aid with PACl. Based on the results, psyllium husk was found to be more effective as coagulant aid with PACl in the removal of COD, color and TSS as compared to alum. Zeta potential test was carried out for leachate, PACl, alum and psyllium husk before and after running the jar test to enhance the results of the jar test experiments. PMID:21507572

  15. Coagulation and complement system in critically ill patients.

    PubMed

    Helling, H; Stephan, B; Pindur, G

    2015-09-01

    Activation of coagulation and inflammatory response including the complement system play a major role in the pathogenesis of critical illness. However, only limited data are available addressing the relationship of both pathways and its assessment of a predictive value for the clinical outcome in intense care medicine. Therefore, parameters of the coagulation and complement system were studied in patients with septicaemia and multiple trauma regarded as being exemplary for critical illness. 34 patients (mean age: 51.38 years (16.57), 15 females, 19 males) were investigated at day 1 of admittance to the intensive care unit (ICU). Leukocytes, complement factors C3a and C5a were significantly (p?< ?0.0500) higher in sepsis than in trauma, whereas platelet count and plasma fibrinogen were significantly lower in multiple trauma. Activation markers of coagulation were elevated in both groups, however, thrombin-antithrombin-complex was significantly higher in multiple trauma. DIC scores of 5 were not exceeded in any of the two groups. Analysing the influences on mortality (11/34; 32.35% ), which was not different in both groups, non-survivors were significantly older, had significantly higher multiple organ failure (MOF) scores, lactate, abnormal prothrombin times and lower C1-inhibitor activities, even more pronounced in early deaths, than survivors. In septic non-survivors protein C was significantly lower than in trauma. We conclude from these data that activation of the complement system as part of the inflammatory response is a significant mechanism in septicaemia, whereas loss and consumption of blood components including parts of the coagulation and complement system is more characteristic for multiple trauma. Protein C in case of severe reduction might be of special concern for surviving in sepsis. Activation of haemostasis was occurring in both diseases, however, overt DIC was not confirmed in this study to be a leading mechanism in critically ill patients. MOF score, lactate, C1-inhibitor and prothrombin time have been the only statistically significant predictors for lethal outcome suggesting that organ function, microcirculation, haemostasis and inflammatory response are essential elements of the pathomechanism and clinical course of diseases among critically ill patients. PMID:26410872

  16. Microwave diagnostics of atmospheric plasmas

    NASA Astrophysics Data System (ADS)

    Scott, David

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

  17. Hydrofluorocarbon ion density of argon- or krypton-diluted CH2F2 plasmas: generation of CH2F+ and CHF2+ by dissociative-ionization in charge exchange collisions

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    Ion densities of CH2F+ and CHF2+ were determined by dissociative ionization pathways in channels of charge exchange collisions, i.e. CH2F2 + M+ → CH2F+ + F + M* and CHF2+ + H +M* [M = Ar, Kr] in CH2F2 plasmas diluted by a rare gas [M]. These channels simultaneously generated counter fragments of charge-neutral H and F atoms of interest for plasma etching processes. In Ar-diluted plasmas, CH2F+ ions predominated due to dissociative ionization between Ar+ [ca. 15.8 eV] and C-F appearance [dissociative ionization] energy [ca. 16 eV] to form CH2F+. In contrast, for Kr-diluted plasmas, C-H appearance energy [ca. 13.8 eV] predominated to produce a larger amount of CHF2+ ions due to a similar channel for charge exchange collisions between Kr+ [ca. 14 eV] and CH2F2. Thus, adding the ratio of Ar and Kr gas to CH2F2 plasmas provided control over the fraction of CH2F+ and CHF2+ ion densities.

  18. [Influence of bigumal on the blood coagulation system and on the anticoagulant effect of heparin].

    PubMed

    kremneva, V F; Ushkalova, E A; Shcheglova, N V

    1986-01-01

    It was found that in the blood plasma bigumal even at high dose (15 mg/kg) exerted no effect on the parameters of partial thromboplastin and thrombin time but increased the blood plasma tolerance to heparin. Both in buffer medium and blood plasma bigumal effectively decreased the specific effect of heparin. Oral acute (5 mg/kg) and long-term (3 mg/kg daily for 5 days) administration of bigumal to rabbits decreased the time of whole blood coagulation, partial thromboplastin time and reduced the sensitivity of animals to heparin. PMID:3817142

  19. Effects Of Continuous Argon Laser Irradiation On Canine And Autopsied Human Cardiac Tissue

    NASA Astrophysics Data System (ADS)

    Ben-Shachar, Giora; Sivakoff, Mark; Bernard, Steven L.; Dahms, Beverly B.; Riemenschneider, Thomas A.

    1984-10-01

    In eight human formalin preserved cardiac specimens, various cardiac and vascular obstructions were relieved by argon laser irradiation. Interatrial communication was also produced by a transar'rial approach in a live dog. In-vivo fresh canine cardiac tissues required power density of at feast 80, 90, and 110 watts/cm2 for vaporization of myocardial, vascular and valvular tissues respectively. The fiber tip to tissue distance (effective irradiation distance) for effective vaporization was less than I mm for vascular and valvular tissues and less than 4 mm for myocardium. Light microscopy showed four zones of histological damage common to all tissues - central crater surrounded by layers of charring, vacuolization and coagulation necorsis. Myocardium showed additionally a layer of normal appearing muscle cells (skip area) surrounded by a peripheral coagulation halo. Laser irradiation effects on valvular tissue showed the most lateral extension of coagulation necrosis. It is concluded that palliation and treatment of certain congenital heart defects by laser irradiation is anatomi-cally feasible and may be safe for in vivo application when low power output and short exposure time are used from a very short irradiation distance.

  20. Assessing blood coagulation status with laser speckle rheology

    PubMed Central

    Tripathi, Markandey M.; Hajjarian, Zeinab; Van Cott, Elizabeth M.; Nadkarni, Seemantini K.

    2014-01-01

    We have developed and investigated a novel optical approach, Laser Speckle Rheology (LSR), to evaluate a patients coagulation status by measuring the viscoelastic properties of blood during coagulation. In LSR, a blood sample is illuminated with laser light and temporal speckle intensity fluctuations are measured using a high-speed CMOS camera. During blood coagulation, changes in the viscoelastic properties of the clot restrict Brownian displacements of light scattering centers within the sample, altering the rate of speckle intensity fluctuations. As a result, blood coagulation status can be measured by relating the time scale of speckle intensity fluctuations with clinically relevant coagulation metrics including clotting time and fibrinogen content. Our results report a close correlation between coagulation metrics measured using LSR and conventional coagulation results of activated partial thromboplastin time, prothrombin time and functional fibrinogen levels, creating the unique opportunity to evaluate a patients coagulation status in real-time at the point of care. PMID:24688816