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1

Flexible argon plasma coagulation treatment of obstructive tracheal metastatic melanoma  

Microsoft Academic Search

Metastases to the tracheobronchial tree may be considered rare, and melanoma metastases to the trachea are very uncommon. We here report the case of a 61-year-old woman with metastatic melanoma to the trachea occurring 2 years after the excision of a right shoulder skin nodule. The patient underwent argon plasma coagulation (APC) recanalization of the malignant airway under flexible bronchoscopy,

Pasquale Capaccio; Andrea Peri; Paolo Fociani; Angelita Ferri; Francesco Ottaviani

2002-01-01

2

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

PubMed

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

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

2008-11-01

3

Endoscopic ablation of Barrett's esophagus using argon plasma coagulation (APC) following surgical laparoscopic fundoplication  

Microsoft Academic Search

Background: Barrett's esopagus (BE) is considered a risk factor for the development of esophageal carcinoma. Recently, partial restoration of squamous mucosa after ablation of BE with endoscopic techniques has been described. Methods: From November 1996 to November 1999, 23 patients with histologically proven BE have been treated by endoscopic argon plasma coagulation (APC) following suppression of gastro-esophageal reflux by laparoscopic

M. Morino; F. Rebecchi; C. Giaccone; S. Taraglio; L. Sidoli; R. Ferraris

2003-01-01

4

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

PubMed

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

Dumot, J A; Greenwald, B D

2008-12-01

5

Effective treatment of solitary rectal ulcer syndrome using argon plasma coagulation  

PubMed Central

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

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

2014-01-01

6

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

PubMed

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

Canady, Jerome; Wiley, Kimberly; Ravo, Biagio

2006-01-01

7

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

PubMed Central

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

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

2014-01-01

8

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

SciTech Connect

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

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

2013-12-01

9

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

Microsoft Academic Search

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

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

2006-01-01

10

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

PubMed Central

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

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

2014-01-01

11

Low risk of contamination with human papilloma virus during treatment of condylomata acuminata with multilayer argon plasma coagulation and CO? laser ablation.  

PubMed

Multilayer argon plasma coagulation (APC) is a new effective method for the treatment of genital warts. We assessed the generation of aerosols containing human papilloma virus (HPV) DNA during treatment of genital warts with multilayer APC and with CO? laser ablation. Surveillance petri dishes, swabs from the glasses and nasolabial folds of the operating physician, and swabs taken from the suction units used during CO? laser ablation were tested by HPV PCR. HPV DNA corresponding to patient derived HPV types of genital warts was not found in any of the petri dishes and swabs obtained during APC treatment. HPV DNA was detected in none of the petri dishes obtained during CO? laser treatment, but in suction filters. In conclusion, both CO? laser ablation with plume suction and APC treatment seem to have a low risk of HPV contamination of the operation room. PMID:21249502

Weyandt, Gerhard H; Tollmann, Franz; Kristen, Peter; Weissbrich, Benedikt

2011-03-01

12

Attachment of gelatin films to tissue using argon beam coagulator.  

PubMed

Cross-linked gelatin films were bonded to heart muscle and to lung pleura and parenchyma using the electrical discharge of an argon beam radiofrequency coagulator. The bonds were stable in warm saline buffer for minutes to hours. Bonding was thought to partly occur through a mechanical interlock of film and tissue elements. The interdigitation of tissue and film arose during exposure to the argon beam, which denatured protein constituents of both, and created a fluidized state that rapidly coalesced. PMID:9619426

Dapper, G; Wallace, D G; Yamamoto, R; Barrett, S; Ly, D; Nguyen, M; Moravcsik, P; Lifrieri, J; Tran, H; Reich, C; Sawyer, P N

1998-01-01

13

Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas  

SciTech Connect

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.

Nunomura, Shota; Kondo, Michio [Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Shiratani, Masaharu; Koga, Kazunori; Watanabe, Yukio [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

2008-08-15

14

FVII Dependent Coagulation Activation in Citrated Plasma by Polymer Hydrogels  

E-print Network

FVII Dependent Coagulation Activation in Citrated Plasma by Polymer Hydrogels Brendan J. Casey and subsequent fibrin formation in citrated plasma. A FVIIa ELISA confirmed the ability of the polymer to induce in this activation. Experiments utilizing coagulation factor depleted and inhibited plasmas indicated that FVII, FX

Kofinas, Peter

15

Diamond film growth argon-carbon plasmas  

DOEpatents

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

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

1998-12-15

16

Contact activation of blood-plasma coagulation  

NASA Astrophysics Data System (ADS)

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

Golas, Avantika

17

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

PubMed

Vulvar cancer is an uncommon disease with approximately 1000 cases reported annually in the UK. Lymph node involvement is an important prognostic indicator. Vulvectomy and bilateral groin node dissection are the preferred surgical treatments for early disease and increase survival. However, significant morbidity with lymphocyst formation and wound breakdown has been reported in more than 50% of cases. We report the first case following use of the PlasmaJet(®) neutral argon coagulation system to reduce postoperative lymphocyst formation. PMID:21792333

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

2011-01-01

18

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

PubMed Central

Vulvar cancer is an uncommon disease with approximately 1000 cases reported annually in the UK. Lymph node involvement is an important prognostic indicator. Vulvectomy and bilateral groin node dissection are the preferred surgical treatments for early disease and increase survival. However, significant morbidity with lymphocyst formation and wound breakdown has been reported in more than 50% of cases. We report the first case following use of the PlasmaJet® neutral argon coagulation system to reduce postoperative lymphocyst formation. PMID:21792333

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

2011-01-01

19

Use of Neutral Argon Plasma in the Laparoscopic Treatment of Endometriosis  

PubMed Central

Background and Objectives: To report the feasibility and safety of the use of a novel energy source that uses an electrically neutral beam of pure argon plasma for the laparoscopic management of endometriosis. Methods: In this prospective pilot study, 20 patients undergoing laparoscopic treatment of endometriosis were included. Characteristic endometriotic lesions throughout the pelvis were vaporized or resected using neutral argon plasma. Specimens were evaluated for the presence of endometriosis and thermal effects on tissue. The bases of the treated lesions were biopsied to determine whether residual endometriosis was present. Results: Neutral argon plasma was used in 18 of the 20 patients for laparoscopic treatment of pelvic endometriosis. All biopsies confirmed complete vaporization or re-section with no residual endometriosis at the base. Endometriosis was identified on pathology in all lesions excised. Thermal effects did not interfere with histologic analysis in any of the lesions. No complications occurred. Conclusion: Neutral argon plasma can be utilized as a multi-functional device that has vaporization, coagulation, and superficial cutting capacities with minimal thermal spread and acceptable outcomes. The use of neutral argon plasma appears to be efficacious and safe for the complete treatment of endometriotic implants. PMID:20202387

Kho, Kimberly A.; Morozov, Vadim

2009-01-01

20

ECR Plasma Sterilisation, Argon and Nitrogen Treated Plasma  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

21

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

22

Properties of radio-frequency heated argon confined uranium plasmas  

NASA Technical Reports Server (NTRS)

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

1976-01-01

23

Features of copper etching in chlorine-argon plasma  

Microsoft Academic Search

Chlorine mixtures with inert gases including argon exhibit promise as plasma feed gases for etching metals and semiconductors in the microelectronics industry. It was shown that even strong dilution of reactive gas with an inert gas (up to 80-90% of the latter) has virtually no effect in decreasing the rate of plasma etching of materials such as silicon and gallium

A. M. Efremov; V. I. Svettsov

1995-01-01

24

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

25

The influence of riboflavin photochemistry on plasma coagulation factors  

PubMed Central

Studies with riboflavin in the 1960s showed that it could be effective at inactivating pathogens when exposed to light. The principal mode of action is through electron transfer reactions, most importantly in nucleic acids. This suggested that it could act as a photosensitizer useful in the inactivation of pathogens found in blood products. Objective To study the influence of photo-inactivation with riboflavin on the coagulation factors of plasma. Methods The photo-inactivation procedure of riboflavin plus light was applied. Fifty isogroup pools of two plasmas were made from 100 U of plasma that were derived from whole blood products that had previously been held overnight. Pools were split into two bags. One of them was photo-inactivated, and post inactivation samples were obtained. The second bag was not photo-inactivated and samples were taken. Total protein, fibrinogen, FII, FV, FVII, FVIII, FIX, FX, FXI, FXIII, antithrombin III, PC, PS, ?-2 antiplasmin and vWF:Ag, the multimeric structure of vWF and ADAMTS-13 were analyzed. Results In plasma, the proteins most sensitive to photo-inactivation were fibrinogen, FXI, FVIII, FV, and FIX (33%, 32%, 30%, 18% and 18% loss, respectively). Coagulation inhibitors, PS, antithrombin III and PC showed little decrease (all 2%). Retention of vWF and ADAMTS-13 were 99% and 88%, respectively. Conclusions As with other pathogen reduction procedures for plasma products, treatment with riboflavin and UV light resulted in reduction in the activity levels of several pro-coagulant factors. Coagulation inhibitors are well preserved. PMID:19782644

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

2011-01-01

26

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...

27

Flush-mounted probe diagnostics for argon glow discharge plasma  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

28

Nanopillar ITO electrodes via argon plasma etching  

SciTech Connect

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

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

2012-07-15

29

Low Temperature Atmospheric Argon Plasma: Diagnostics and Medical Applications  

NASA Astrophysics Data System (ADS)

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

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

30

Laser-induced fluorescence measurement of argon in argon-xenon plasma sheath boundary with tunable diode laser  

Microsoft Academic Search

Summary form only given. The Bohm sheath criterion in single and two-species plasma is studied with laser-induced fluorescence (LIF) using a diode laser. Xenon is added to a low pressure argon unmagnetized DC hot filament discharge confined by surface multidipole magnetic fields. The argon II transition sequence at 668.614 nm is adopted for optical pumping to detect the fluorescence from

Dongsoo Lee; N. Hershkowitz

2006-01-01

31

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

32

Plasma core reactor simulations using RF uranium seeded argon discharges  

NASA Technical Reports Server (NTRS)

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

Roman, W. C.

1975-01-01

33

Plasma core reactor simulations using RF uranium seeded argon discharges  

NASA Technical Reports Server (NTRS)

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

Roman, W. C.

1976-01-01

34

Analysis of Surface Sterilization and Properties of Medical Poly(tetrafluoroethylene) in Remote Argon Plasma  

Microsoft Academic Search

We have used a remote-argon-plasma reactor in which the active species can be separated at a special plasma field. Argon gas is used as the work gas. In this remote argon plasma, the distribution of electrons, ions, and radicals and germicidal effect (GE) of Escherichia coli on the surface of medical poly(tetrafluoroethylene) (PTFE) film are studied. Then surface properties of

Hong-Xia Liu; Jie-Rong Chen

2008-01-01

35

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

E-print Network

Fluid simulation of a pulsed-power inductively coupled argon plasma D. P. Lymberopoulos Applied to investigate the spatiotemporal dynamics of a pulsed-power inductively coupled argon plasma at 10 mHz) bias to the substrate in the afterglow of an inductively coupled plasma ICP source.10 It was suggested

Economou, Demetre J.

36

Effect of the levitating microparticle cloud on radiofrequency argon plasma  

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

37

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

38

Numerical simulation of alumina spraying in argon-helium plasma jet  

Microsoft Academic Search

A 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

C. H. Chang

1992-01-01

39

Nonthermal atmospheric argon plasma jet effects on Escherichia coli biomacromolecules.  

PubMed

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

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

2013-12-01

40

Filamentation in argon microwave plasma at atmospheric pressure  

SciTech Connect

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

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

2009-05-01

41

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

Microsoft Academic Search

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

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

2011-01-01

42

Diode Laser Based LIF Diagnostics for Argon and Helium Plasmas.  

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

43

The influence of tamoxifen on plasma coagulation and serous fibrinolysis.  

PubMed

Selected parameters of coagulation and fibrinolysis were determined in 25 postmenopausal women, treated chronically for breast cancer with the use of tamoxifen. The significant influence of tamoxifen therapy on the serous fibrinolysis parameters was found. The time of euglobulin lysis was shorter, the concentration of alpha 2-antiplasmin decreased, and plasminogen concentration increased. The content of antithrombin III, fibrinogen, and caolin-cephalin time did not change significantly during therapy, except the prothrombin rate which increased. Tamoxifen is an important medicine with beneficial influence on the fibrinolytic system, without affecting the serous coagulation system. PMID:8200368

Jankowski, J; Ramlau, C; Kopczynski, Z; Boryska, M

1993-01-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

45

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

Microsoft Academic Search

Water vapor was added to the feeding gas of a continuous atmospheric argon (Ar) microwave plasma jet to study its influence on plasma shape, plasma gas temperature, and OH radical concentrations. The plasma jet was created by a 2.45 GHz microwave plasma source operating at constant power of 104 W with H2O-Ar mixture flow rate of 1.7 standard liter per

Nimisha Srivastava; Chuji Wang

2011-01-01

46

Spectroscopic Diagnostics of Atmospheric Argon Microwave Plasma Based on an Inductive Coupling Window-Rectangular Resonator  

NASA Astrophysics Data System (ADS)

We present a novel microwave plasma source based on an inductive coupling window-rectangular resonator. A definite volume of atmospheric argon microwave plasma is excited in the source under the input of several kilowatts of microwave power operating at 2.45 GHz. The excitation temperature and electron temperature of the argon plasma are separately researched by using Boltzmann plot and line-to continuum intensity ratio of Ar I spectral lines. Its electron density is inferred from the Stark broadening of the H? line at 486.13 nm.

Wang, Zhong; Zhang, Gui-Xin; Liu, Cheng; Jia, Zhi-Dong

2014-05-01

47

Multidimensional Simulation of Plasma in Argon through a Shock in Hypersonic Flow  

E-print Network

Multidimensional Simulation of Plasma in Argon through a Shock in Hypersonic Flow Amrita K. Lonkar in gases at hypersonic speeds. A plasma is composed of multiple species in thermo-chemical nonequlibrium major advancements in the field of hypersonics in the past quarter century. Rocket- powered launch

Alonso, Juan J.

48

Multidimensional Simulation of Plasma in Argon through a Shock in Hypersonic Flow  

E-print Network

Multidimensional Simulation of Plasma in Argon through a Shock in Hypersonic Flow Amrita K. Lonkar in gases at hypersonic speeds. A plasma is composed of multiple species in thermo-chemical nonequlibrium of hypersonics in the past quarter century. Rocket- powered launch vehicles typically achieve hypersonic speeds

Alonso, Juan J.

49

Coagulation parameters as a guide for fresh frozen plasma transfusion practice: A tertiary hospital experience  

PubMed Central

Introduction: The appropriate use of blood and blood products means the transfusion of safe blood products only to treat a condition leading to significant morbidity or mortality, which cannot be prevented or managed effectively by other means. The safety and effectiveness of transfusion depend on the appropriate clinical use of blood and blood products. This study was conducted to review the practice of fresh frozen plasma usage (FFP) for transfusion, based on the coagulation profile, requested by various departments in the Hospital Universiti Sains Malaysia (HUSM). Methodology: A retrospective review of blood bank records and coagulation profile results of the patients given FFP from October to December 2006, in Hospital USM was undertaken. The criteria set by the College of American Pathologists in 1994, were used as the guidelines. Results: One thousand six hundred and ninety-eight units of FFP were used during this study period. Only 806 (47.47%) FFP units were deemed appropriate. 20.38% were based on studies without any coagulation tests prior to transfusion and 21.13% were transfused for mild prolongation of coagulation test results. About 6.41% requested FFP in the setting of normal coagulation results. Conclusion: Our results showed that a significant proportion of the FFP transfusion was not guided by the coagulation profile. We recommend that a continuous education on FFP transfusion may help to guide the appropriate request for FFP. PMID:20376262

Wan Haslindawani, W. M.; Wan Zaidah, A.

2010-01-01

50

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

Microsoft Academic Search

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

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

2004-01-01

51

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

E-print Network

the influence of nine control parameters (such as carrier gas flow rate, injector (internal diameter), powder size distribution, arc current, size of plasma gun nozzle, plasma gas nature, flow rate and increases the length of jet high-temperature region and the mass flow rate but decreases the gas specific

52

Comparison of plasma-sprayed coatings produced in argon or nitrogen atmosphere  

NASA Astrophysics Data System (ADS)

When spraying is conducted at ambient atmosphere, the entrainment of air cools the plasma jet and affects its expansion. It can also cause oxidation or chemical decomposition of the sprayed materials. Inert plasma spraying (IPS), generally conducted in an argon atmosphere, prevents these phenomena. However, the main drawbacks of IPS in comparison with air plasma spraying are the capital and operating costs. This paper presents a study in which nitrogen is used as a substitute for conventional argon atmosphere, thus reducing costs by 25 to 30%. Titanium carbide and niobium powders were sprayed in both argon and nitrogen atmospheres. Cryogenic cooling of the substrate was used during the spray process. This helps to maintain a low temperature in the chamber, produce thick coatings, and allows the use of substrate materials that are sensitive to heat. The velocity, temperature, and composition fields of the argon-hydrogen plasma jet flowing in argon or nitrogen at atmospheric pressure are compared from numerical simulation. The adhesion, roughness, and microstructure of the niobium and TiC coatings produced in both atmospheres are discussed as well as their nitrogen content.

Leylavergne, M.; Vardelle, A.; Dussoubs, B.; Goubot, N.

1998-12-01

53

Measurement Of The Distribution Of Ionization States In An Argon Plasma  

NASA Astrophysics Data System (ADS)

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

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

1988-02-01

54

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

PubMed

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

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

1990-07-01

55

Plasma parameters in a planar dc magnetron sputtering discharge of argon and krypton  

Microsoft Academic Search

The electron energy distribution function (EEDF) and plasma parameters in a planar dc magnetron sputtering discharge in argon and krypton were determined using a Langmuir probe. Two groups of electrons are observed in the discharge. The electron temperature of the cold electrons is roughly independent of the discharge pressure, while the electron temperature of the hot electrons decreases with increased

P. Sigurjonsson; J. T. Gudmundsson

2008-01-01

56

Lattice Boltzmann Computation of Plasma Jet Behaviors : part II Argon-Nitrogen Mixture  

E-print Network

measurements. These studies and others ones deal with 3D, 2D, and 2D1/2(axisymmetric), with and without the applications to simulating flows with temperature-dependent diffusion parameters (viscosity and diffusivity instead of air as surrounding gas of a laminar argon plasma jet avoids undesired oxidation of metallic

Paris-Sud XI, Université de

57

Experimental characterization of an atmospheric argon plasma jet generated by an 896 MHz microwave system  

Microsoft Academic Search

This paper presents experimental results on an atmospheric plasma jet generated by a rectangular wave-guide based microwave system operating at 896 MHz. Argon gas emerging from a copper nozzle, which is placed inside the wave-guide short circuited at one end (hereafter referred to as the cavity for convenience), jets into the atmosphere through an aperture in the cavity wall. The

J. D. Yan; C. F. Pau; S. R. Wylie; M. T. C. Fang

2002-01-01

58

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

PubMed

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

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

2004-08-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

60

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

SciTech Connect

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

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

2012-02-15

61

Contact activation of blood coagulation is inhibited by plasma factor XIII b-chain.  

PubMed

The effect of the purified bovine plasma factor XIII b-chain on contact activation of blood coagulation was studied in human and bovine plasma using either an ellagic acid-phospholipid suspension (Cephotest) or dextran sulfate as activating surface. Contact activation was monitored by the generation of amidolytic activity towards a synthetic chromogenic substrate (S-2302) for factor XIIa and plasma kallikrein. The factor XIII b-chain, which is released from tetrameric factor XIII (a2b2) in the late stages of blood coagulation, inhibits contact activation induced by both activation surfaces mentioned. It was shown that a 5 min preincubation of the factor XIII b-chain with the activation surface increases its inhibitory effect. Light scattering measurements indicated a concurrent binding of the factor XIII b-chain to the Cephotest material. Because factor XIII (a2b2) itself had no such inhibitory activity, the present finding that the factor XIII b-chain inhibits contact activation may point to a novel feed-back inhibition mechanism of blood coagulation. PMID:2459802

Halkier, T; Magnusson, S

1988-08-01

62

Driving frequency dependence of capacitively coupled plasmas in atmospheric argon  

NASA Astrophysics Data System (ADS)

The role of the driving field frequency fd of a cool atmospheric plasma (CAP) is investigated for values around f_d^\\ast =13.56\\,MHz using a two-dimensional fluid numerical model applied to a parallel plate configuration. It is found that keeping the voltage constant the current amplitude roughly scales with f_d^2 ; a tendency that can be understood using a RC circuit model of the plasma-sheath configuration. Moreover, it is seen that the electron density increases faster than the density of the excited species. This implies that plasma heating will increase relatively more than plasma reactivity so that the basic feature of the CAP, to be cool and reactive, will weaken for increasing fd-values.

Atanasova, M.; Sobota, A.; Brok, W.; Degrez, G.; van der Mullen, J. J. A. M.

2012-08-01

63

Axial plasma density propagation of barrier discharge non-thermal plasma bullets in an atmospheric pressure argon gas stream  

NASA Astrophysics Data System (ADS)

The characteristics of volume-averaged plasma density on axial propagation for atmospheric argon (Ar) plasma bullets are experimentally investigated. The non-thermal plasma bullets are ejected through a glass tube into the surrounding ambient air. Taking into consideration the time and space profile of the plasma movement, the plasma propagation is measured using a Rogowski coil. The plasma density is evaluated from the propagation velocity and the current magnitude. The plasma density profiles are presented as functions of the applied voltage and the length of growth. The plasma density is in the order of 1016 m-3 and the propagation velocity is in the order of 105 m s-1. These values are similar to those of weakly ionized non-thermal plasma jets.

Ohyama, R.; Sakamoto, M.; Nagai, A.

2009-05-01

64

[Technical peculiarities of the argon-plasma welding of gastrointestinal walls wounds in experimental environment].  

PubMed

A new method of the live biological tissues connection, using thermal energy of a high-temperature argon plasma, constituting perspective trend of application of a new nonsuture methods of the tissues connection, original for the world practice, was elaborated in the Department of Experimental Surgery together with the Institute of welding named after Academician E. O. Paton NAS of Ukraine. The argon-plasma welding application secure safe adhesion of the connecting surfaces formation due to the protein complexes temperature denaturation occurrence. The absence of foreign bodies in the connection zone as well as the presence of the plasma flow bacterocidal properties secure, while application of this new method, a significant lowering of a bacterial soiling of the formatted anastomoses, not interfering with the tissue natural regeneration process course. PMID:18982726

Terekhov, G V; Furmanov, Iu A; Gvozdetski?, V S; Savitskaia, I M

2008-06-01

65

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

SciTech Connect

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

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

1995-06-01

66

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

NASA Astrophysics Data System (ADS)

A nonequilibrium Ar /O2 plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar /O2 plasma jet at an exposure distance of 0.5-1.5cm ranges from 5 to 57s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

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

2007-09-01

67

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

NASA Astrophysics Data System (ADS)

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

Makonnen, Yoseif; Beauchemin, Diane

2014-09-01

68

Plasma Diagnostics Using K-Line Emission Profiles of Argon  

E-print Network

K-line profiles emitted from a warm dense plasma environment are used for diagnostics of Ar droplet plasmas created by high energy laser pulses. We observe temperature gradients within the Ar droplet from cold temperatures of the order of some 10 eV up to higher temperatures of about 170 eV. Non-perturbative wave functions are calculated as well as ionization energies, binding energies and relevant emission energies using a chemical {\\it ab initio} code. The plasma screening is considered within a perturbative approach to the Hamiltonian. The plasma effect influences the many-particle system resulting in energy shifts due to electron-ion and electron-electron interaction. With this approach we get a good reproduction of spectral features that are strongly influenced by ionization and excitation processes within the plasma. Comparing with the widely known FLYCHK code, counting for internal degrees of freedom (bound states) and treating pressure ionization within our quantum statistical approach leads to differ...

Chen, Yiling; Reinholz, Heidi; Röpke, Gerd

2014-01-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

70

Experimental Investigation of Laser-sustained Plasma in Supersonic Argon Flow  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

71

Comparison between experiment and simulation for argon inductively coupled plasma  

SciTech Connect

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.

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

2009-11-15

72

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

PubMed

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

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

1988-07-01

73

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

74

Transparent conducting zinc oxide thin film prepared by electron beam evaporation technique with argon plasma assistance  

Microsoft Academic Search

Zinc oxide thin film has been deposited on glass substrate by electron beam evaporation with argon plasma assistance. Undoped polycrystalline ZnO pellets (purity = 99%) were used as source material. The film was characterized by atomic force microscopy, UV\\/VIS\\/NIR spectroscopy, electrical resistivity and Hall effect measurements and X-ray diffraction. The thicknesses were measured using a Dektak profilometer and the electrical

V. D. Falcao; M. E. L. Sabino; D. O. Miranda; A. S. A. C. Diniz; J. R. T. Branco

2008-01-01

75

Plasma Chemistry of Octafluorocyclopentene/Argon/Oxygen Mixtures  

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

76

Laboratory observation of a very low frequency instability in an argon plasma  

NASA Technical Reports Server (NTRS)

Very low frequency (50 to 500 Hz) self-excited electrostatic waves are detected in a cylindrical argon plasma column with a weak axial magnetic field (10 to 100 G). The waves propagate azimuthally with a phase velocity in the electron diamagnetic drift direction, but with a speed at least an order of magnitude less than the ion acoustic speed. A number of known plasma instabilities are considered as possible explanations, though most of them do not seem to account for the observed characteristics of the waves.

Reinleitner, L.; Dangelo, N.

1982-01-01

77

Ion beam formation in a low-pressure geometrically expanding argon plasma  

SciTech Connect

Supersonic ion beam formation has been observed in a geometrically expanding low-pressure inductively coupled argon plasma. It is found that the ion beam is only observed below 3 mTorr and only when the discharge is operated in inductive mode. The geometrical expansion of the plasma induces density and potential gradients leading to the ion beam formation. The ion beam energy increases with decreasing source tube radius. The results show that ion beam formation can be achieved by geometrical expansion alone and that the ion beam energy depends on the ratio of the cross-sectional area of the source and expansion region.

Corr, C. S.; Zanger, J.; Boswell, R. W.; Charles, C. [Space Plasma, Power, and Propulsion group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australia Capital Territory 0200 (Australia)

2007-12-10

78

Self-formation of lead telluride nanostructures during argon plasma etching of single-crystal wafers  

NASA Astrophysics Data System (ADS)

In this work we report a phenomenon of PbTe nano- and microstructure selfformation that takes place during dry etching of lead telluride (111)-oriented single-crystal wafers with 4 at.% excess tellurium in RF high-density low-pressure inductively coupled argon plasma. Using scanning electron microscopy and energy dispersive X-ray spectroscopy investigations it is established that during the plasma treatment high sputtering rates are accompanied by active redeposition processes on crystal surface and on the inner side of the Si etching mask resulting in a nanostructure arrays self-formation via vapour-liquid-solid mechanism.

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

2014-10-01

79

Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics  

SciTech Connect

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

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

2013-04-15

80

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

SciTech Connect

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

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

2009-12-01

81

Five-minute preparation of platelet-poor plasma for routine coagulation testing.  

PubMed

Clinical and Laboratory Standard Institute guidelines require that routine coagulation tests are performed with platelet-poor plasma (< 10,000 platelets/microL) and prepared from whole citrated blood centrifuged at low speed for 10-30 minutes. To compare results obtained from plasma centrifuged for 5 minutes at 3000 g or for 10 minutes at 2000 g, 46 blood samples from normal healthy adults were assayed for prothrombin time, international normalized ratio and activated partial thromboplastin time. No significant differences were found in test results and it was concluded that 5 minutes centrifugation at 3000 g is a reliable and useful option to reduce the turnaround time for these tests. PMID:20799581

Sultan, A

2010-02-01

82

Functionalization of carbon nanotubes by argon plasma-assisted ultraviolet grafting  

SciTech Connect

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.

Yan, Y.H.; Chan-Park, M.B.; Zhou, Q.; Li, C.M.; Yue, C.Y. [School of Mechanical and Aerospace Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

2005-11-21

83

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

SciTech Connect

The gas temperature is an important parameter in many applications of atmospheric pressure microwave discharges (MW). That is why it is necessary to study the influence of that temperature on the plasma characteristics. Our investigation is based on a self-consistent model including the wave electrodynamics and gas-discharge kinetics. We adopt a blocks' energy structure of the argon excited atom. More specifically, we consider 7 different blocks of states, namely 4s, 4p, 3d, 5s, 5p, 4d, and 6s. Each block k is characterized by its effective energy uk (derived as an average energy of all levels in the block), as well as its effective g-factor and population. The argon dimmer, atomic and molecular ions are also taken into account in the model. We solve the Boltzmann equation in order to get the electron energy distribution function and the necessary rate constants of the elementary processes. The collisional-radiative part of the model is based on 87 processes. As a result we obtain the electron and ions' number densities, mean electron energy, mean power for sustaining an electron--ion pair in the discharge bulk, as well as the population of the excited blocks of states of the argon atom as functions of the gas temperature.

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

2008-03-19

84

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

SciTech Connect

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

Adam B. Sefkow and Samuel A. Cohen

2009-04-09

85

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

87

Cylindrical stationary striations in surface wave produced plasma columns of argon  

SciTech Connect

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

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

2007-12-15

88

Effects of post-deposition argon implantation on the memory properties of plasma-deposited silicon nitride films  

Microsoft Academic Search

Post-deposition ion implantation has been used to introduce argon into plasma-enhanced chemically vapor deposited silicon nitride films in an attempt to influence the transfer, trapping, and emission of charge during write\\/erase exercising of the metal-silicon nitride-silicon oxide-silicon structure. Argon was implanted into the SiH4 -NH3 -N2 deposited films at energies ranging from 25 to 75 keV, current densities ranging from

Q. A. Shams; W. D. Brown

1989-01-01

89

Enhancement of adhesion between antireflection coating and cellulose triacetate by surface pretreatment using argon-helium plasma.  

PubMed

The adhesion of optical thin films on cellulose triacetate (TAC) was enhanced with surface pretreatment by argon-helium plasma. The optical properties, water contact angle, surface morphology, and thin film adhesion of TAC substrate that had been treated with different plasma gases were also investigated. An antireflection coating adhered well to TAC with an appropriate interface layer. PMID:18449275

Wang, Hsuan-Wen; Tang, Chien-Jen; Lee, Cheng-Chung

2008-05-01

90

Plasma surface modification of aluminum alloy samples treated with argon discharge conditioning  

SciTech Connect

The study of change in surface properties of metals and their alloys under plasma processing has a wide range of applications. It affords range, flexibility, ease and accuracy of process control at low cost as compared to other techniques. All the applications of non-equilibrium plasmas involve processes like sputtering, etching, polymerization, surface modification, etc. It is expected for industries to get a final product with specific properties with high reliability and repeatability. Stainless steel is used to construct UHV chambers. A comparative study of outgassing rates show that SS can be replaced by aluminium alloy for UHV chambers. Turbomoleculer Pumping Unit evacuates a cylindrical discharge chamber of SS304 with various ports on it. A hollow cathode DC glow discharge in argon for different discharge pressures and for different discharge current densities respectively, is used for treating chemically cleaned ASA6063 aluminium alloy samples, keeping all other parameters constant. TMP unit evacuates SS304 chamber to a base pressure 3 x 10{sup {minus}7}mbar. The processing gas argon is introduced through a leak valve and with the help of a throttling valve the pressure in the discharge chamber is adjusted to the operating pressure 10{sup {minus}2}mbar. The wall temperature and discharge time were the same in all treatments. The Scanning Electron Microscope (SEM) is used to examine processed surfaces and to study topographical features.

Karandikar, S.J.; Samant, C.C.; Gogawale, S.V.

1999-07-01

91

Modification of tapioca starch by non-chemical route using jet atmospheric argon plasma.  

PubMed

Non-chemical modification of tapioca starch was investigated using jet atmospheric argon plasma treatment. Two forms of starch slurry, i.e. granular starch (G) and cooked starch (C), were jet-treated by argon plasma generated by supplying input power of 50 W (denoted as G50 and C50 samples) and 100 W (denoted as G100 and C100 samples) for 5 min. Physical, rheological, and structural characteristics of the modified starch were investigated. The G50 and C100 samples had lower paste clarity but higher thermal stability and performed stronger gels (G50 only) compared to their control counterparts. On the other hand, the analyzed properties of the G100 and C50 samples showed the opposite trend. FTIR and (1)H NMR results revealed that the relative areas of COC and OH peaks were changed after the treatment. Cross-linking reaction seemed to predominantly take place for the G50 and C100 samples, whereas depolymerization predominated for the G100 and C50 samples. PMID:24507348

Wongsagonsup, Rungtiwa; Deeyai, Panakamol; Chaiwat, Weerawut; Horrungsiwat, Sawanee; Leejariensuk, Kesini; Suphantharika, Manop; Fuongfuchat, Asira; Dangtip, Somsak

2014-02-15

92

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

SciTech Connect

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

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

2010-03-15

93

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

94

Generation of Cold Argon Plasma Jet at the End of Flexible Plastic Tube  

E-print Network

This brief communication reports a new method for generation of cold atmospheric pressure plasma jet at the downstream end of a flexible plastic tube. The device consists of a small chamber where dielectric barrier discharge (DBD) is ignited in Argon. The discharge is driven by a conventional low frequency AC power supply. The exit of DBD reactor is connected to a commercial flexible plastic tube (up to 4 meters long) with a thin floating Cu wire inside. Under certain conditions an Ar plasma jet can be extracted from the downstream tube end and there is no discharge inside the plastic tube. The jet obtained by this method is cold enough to be put in direct contact with human skin without electric shock and can be used for medical treatment and decontamination.

Kostov, Konstantin G; Prysiazhnyi, Vadym

2014-01-01

95

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

96

Behavior of a porous particle in a radiofrequency plasma under pulsed argon ion beam bombardment  

NASA Astrophysics Data System (ADS)

The behavior of a single porous particle with a diameter of 250 ?m levitating in a radiofrequency (RF) plasma under pulsed argon ion beam bombardment was investigated. The motion of the particle under the action of the ion beam was observed to be an oscillatory motion. The Fourier-analyzed motion is dominated by the excitation frequency of the pulsed ion beam and odd higher harmonics, which peak near the resonance frequency. The appearance of even harmonics is explained by a variation of the particles's charge depending on its position in the plasma sheath. The Fourier analysis also allows a discussion of neutral and ion forces. The particle's charge was derived and compared with theoretical estimates based on the orbital motion-limited (OML) model using also a numerical simulation of the RF discharge. The derived particle's charge is about 7-15 times larger than predicted by the theoretical models. This difference is attributed to the porous structure of the particle.

Wiese, Ruben; Sushkov, Vladimir; Kersten, Holger; Ikkurthi, Venkata R.; Schneider, Ralf; Hippler, Rainer

2010-03-01

97

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

98

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

99

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

SciTech Connect

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

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

2008-01-01

100

Investigations of a microwave plasma source operating with air, N2, CO2 and argon gases  

NASA Astrophysics Data System (ADS)

The present contribution will report on the development of a 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 conventional arrangement for MPT, including cylindrical open-ended dielectric quartz tube, plasma generated with molecular gases have been found to be homogeneous 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 is 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 N2+ First Negative and N2 2nd Positive systems. Making the common assumption that the internal energy levels of molecular species are populated according to a Boltzmann distribution and making no assumption concerning the total species concentration similarly to [1], comparisons between measured and calculated radiative signature of molecular systems evidence for the achievement of thermal equilibrium and slight departure to Saha equilibrium.

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

2012-02-01

101

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

NASA Astrophysics Data System (ADS)

Experiments and modeling of the plasma-microwave interaction have been performed in a coaxial microwave plasma source at a field frequency of 2.45 GHz generating argon plasmas at pressures of 20 and 40 millibars and a ratio of flow rate to pressure of 0.125 sccm/Pa. The incident microwave power between 100 W and 300 W is supplied in a regime of a pulse-width modulation with cycle duration of 110 ms and a power-on time of 23 ms. The experiments are based on heterodyne reflectometry and microwave interferometry at 45.75 GHz. They provide the temporal behaviour of the complex reflection coefficient, the microwave power in the plasma, as well as the electron density in the afterglow zone of the discharge. The self-consistent spatially two-dimensional and time-dependent modeling complements the analysis of the plasma-microwave interaction delivering the plasma and electromagnetic field parameters. The consolidating experimental observations and model predictions allow further characterizing the plasma source. The generated plasma has a core occupying the region close to the end of the inner electrode, where maximum electron densities above 1020 m-3 and electron temperatures of about 1 eV are observed. Due to a longer outer electrode of the coaxial structure, the plasma region is extended and fills the volume comprised by the outer electrode. The electron density reaches values of the order of 1019 m-3. The heating of the gas occurs in its great part due to elastic collisions with the plasma electrons. However, the contribution of the convective heating is important especially in the extended plasma region, where the gas temperature reaches its maximum values up to approximately 1400 K. The temporally and spatially resolved modeling enables a thorough investigation of the plasma-microwave interaction which clearly shows that the power in-coupling occurs in the region of the highest electron density during the early stage of the discharge. In the steady state phase, however, the power in-coupling occurs close to the source walls where the electron density is significantly lower than on the discharge axis.

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

2014-04-01

102

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

PubMed

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

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

2014-04-01

103

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

PubMed Central

A quartz crystal microbalance (QCM) biosensor with nanogram sensitivity has been constructed through a reasonable designing and biological processing of the piezoelectric quartz crystals. Due to its highly sensitivity, real time detection and low cost, the proposed QCM biosensor has a promising potential in blood coagulation research. In the current study, the QCM biosensor was used to determine the activated partial thromboplastin time (APTT) for 120 anticoagulated plasma specimens. A good linear relationship was found in a double-logarithmic plot of APTT versus fibrinogen concentration in the range of 1.58–6.30 g/L. For factor VIII, the detection range by the QCM biosensor is 0.0185–0.111 mg/L. The QCM biosensor results were compared with those obtained by commercial optical coagulometry and a good agreement (correlation coefficient is 0.949 for fibrinogen, and 0.948 for factor VIII) was reached. Furthermore, the QCM determination can be completed within 10 min. Our study suggested that the proposed QCM biosensor could provide for more convenient and time saving operations, which may be useful in clinical situations for rapid monitoring of anticoagulant therapy using small volume (20 ?L) plasma specimens. PMID:23708275

Yao, Chunyan; Qu, Ling; Fu, Weiling

2013-01-01

104

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

PubMed

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

Nielsen, Vance G; Garza, Joshua I

2014-12-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

106

Ionization in inductively coupled argon plasmas studied by optical emission spectroscopy  

SciTech Connect

Contribution of stepwise ionization to total ionization was experimentally investigated in low-pressure inductively coupled argon plasmas. In the pressure range 3-50 mTorr, optical emission spectroscopy was employed to determine metastable fractions (metastable density relative to ground state density) by measuring the emission intensity of selected lines. The measured metastable fractions were in good agreement with the calculation, showing a dependence on the discharge pressure. The rate of stepwise ionization was estimated from the excited level densities (measurements and model predictions) and their ionization rate coefficients. It is observed that at relatively low discharge pressures (<10 mTorr) the ionization is mainly provided by the direct ionization, whereas at higher pressure the stepwise ionization is predominant with increasing absorbed power.

Lee, Young-Kwang; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2011-01-01

107

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...

108

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

SciTech Connect

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

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

2011-09-01

109

Investigations of laser-induced plasma in argon by Thomson scattering  

NASA Astrophysics Data System (ADS)

The Thomson scattering method was applied to quantify the electron number density and temperature of a laser spark formed in argon. The laser spark was generated by focusing a 15 mJ beam from the second harmonic (? L = 532 nm) of a nanosecond Nd:YAG laser with an 80 mm focal length lens. Images of the spark emission were obtained for times between 1 ns and 20 ?s after the laser pulse in order to characterize its spatial evolution. The electron density and temperature for the core of the plasma plume at different instants of its evolution were determined from the Thomson scattered spectra of another nanosecond Nd:YAG laser (532 nm, 10 to 60 mJ/pulse). In the time interval between 400 ns and 10 ?s between the laser induced plasma and Thomson scattering probe pulses, we found ne and Te to decrease from 4.3 × 10 23 m - 3 to 2.4 × 10 22 m - 3 and from 50 700 K to 11 100 K, respectively. Special care was paid to the plasma disturbance by the probe laser pulse in Thomson scattering experiments due to absorption of laser photons by electrons through the inverse bremsstrahlung process.

Mendys, A.; Dzier??ga, K.; Grabiec, M.; Pellerin, S.; Pokrzywka, B.; Travaillé, G.; Bousquet, B.

2011-09-01

110

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

SciTech Connect

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

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

2013-11-15

111

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

PubMed

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

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

2004-01-01

112

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

Microsoft Academic Search

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

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

1993-01-01

113

Halftoning band gap of InAs\\/InP quantum dots using inductively coupled argon plasma-enhanced intermixing  

Microsoft Academic Search

Inductively coupled argon plasma-enhanced intermixing of InAs\\/InP quantum dots grown on InP substrate is investigated. Intermixing is promoted by the near-surface defects generated by plasma exposure in annealing at a temperature of 600 °C for 30 s. The annealing results in a maximum differential band-gap blueshift of 106 nm but a thermal shift of only 10 nm. Band-gap halftones are

D. Nie; T. Mei; C. D. Xu; J. R. Dong

2006-01-01

114

Proteomic analysis of the coagulation reaction in plasma and whole blood using PROTOMAP.  

PubMed

Proteases are critical in many physiological processes and the human genome encodes for 566 predicted proteolytic enzymes. Therefore, there is great interest in identifying and characterizing physiologic protease-substrate relationships. The coagulation cascade is a well-described network of serine proteases. However, new interactions of the coagulation cascade with other biological pathways have been discovered only recently. Therefore, we hypothesized that a non-biased protease degradomics analysis of the physiologic coagulation reaction would identify new interactions between the coagulation cascade and other pathways. We used the recently described PROTOMAP technique to profile the complete coagulation degradome. This analysis detected virtually all of the proteins of the coagulation cascade and identified a majority of the expected proteolytic events, suggesting significant coverage of the coagulation degradome. Multiple potential new proteolytic cleavages were detected, including two of transmembrane proteins that may be shed from the surface of blood cells. In addition, this analysis was able to identify several new potentially secreted proteins. A significant majority of the newly identified events were of proteins involved in innate immunity (complement and inflammation). This highlights potential new areas of crosstalk between these linked systems. Future studies will elucidate the details and functional consequences of these proteolytic events during coagulation. PMID:21584940

Niessen, Sherry; Hoover, Heather; Gale, Andrew J

2011-06-01

115

An equilibrium study of metal ion binding to human plasma coagulation factor XIII.  

PubMed Central

1. The binding of Ca2+ to plasma coagulation Factor XIII from man and from cow caused a small decrease in the intrinsic fluorescence of the protein with a dissociation constant of 0.1 mM. A similar decrease was observed with the thrombin-activated Factors (Factors XIIa). The decrease in protein fluorescence was also caused by both Ni2+ and Mn2+ but not by Mg2+. 2. 45Ca2+ binding was directly demonstrated by equilibrium dialysis. Ca2+ at 0.2 mM bound to Factor XIII (a2b2) and Factor XIIIa (a'2b2) but not to isolated b2-protein. A tight-binding site for Ca2+ is associated with the a-subunits. 3. The Ca2+ essential for the enzyme activity of Factor XIII from man, pig and cow can be replaced by Ni2+, Cu2+, La3+, Mn2+, Fe3+, Y3+, Co2+, Sr2+ or Tb3+, but not by Mg2+. Images Fig. 1. Fig. 2. PMID:629762

Lewis, B A; Freyssinet, J M; Holbrook, J J

1978-01-01

116

An equilibrium study of metal ion binding to human plasma coagulation factor XIII.  

PubMed

1. The binding of Ca2+ to plasma coagulation Factor XIII from man and from cow caused a small decrease in the intrinsic fluorescence of the protein with a dissociation constant of 0.1 mM. A similar decrease was observed with the thrombin-activated Factors (Factors XIIa). The decrease in protein fluorescence was also caused by both Ni2+ and Mn2+ but not by Mg2+. 2. 45Ca2+ binding was directly demonstrated by equilibrium dialysis. Ca2+ at 0.2 mM bound to Factor XIII (a2b2) and Factor XIIIa (a'2b2) but not to isolated b2-protein. A tight-binding site for Ca2+ is associated with the a-subunits. 3. The Ca2+ essential for the enzyme activity of Factor XIII from man, pig and cow can be replaced by Ni2+, Cu2+, La3+, Mn2+, Fe3+, Y3+, Co2+, Sr2+ or Tb3+, but not by Mg2+. PMID:629762

Lewis, B A; Freyssinet, J M; Holbrook, J J

1978-02-01

117

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

118

Laser light scattering in a laser-induced argon plasma: Investigations of the shock wave  

NASA Astrophysics Data System (ADS)

Shock wave produced by a laser induced spark in argon at atmospheric pressure was examined using Rayleigh and Thomson scattering. The spark was generated by focusing a laser pulse from the second harmonic (? = 532 nm) of a nanosecond Nd:YAG laser using an 80 mm focal length lens, with a fluence of 2 kJ·cm- 2. Images of the spark emission were recorded for times between 30 ns and 100 ?s after the laser pulse in order to characterize its spatial evolution. The position of the shock wave at several instants of its evolution and for several plasma regions was determined from the Rayleigh-scattered light of another nanosecond Nd:YAG laser (532 nm, 40 J·cm- 2 fluence). Simultaneously, Thomson scattering technique was applied to determine the electron density and temperature in the hot plasma core. Attempts were made to describe the temporal evolution of the shock wave within a self-similar model, both by the simple Sedov-Taylor formula as well as its extension deduced by de Izarra. The temporal radial evolution of the shock position is similar to that obtained within theory taking into account the counter pressure of the ambient gas. Density profiles just behind the shock front are in qualitative agreement with those obtained by numerically solving the Euler equations for instantaneous explosion at a point with counter pressure.

Pokrzywka, B.; Mendys, A.; Dzier??ga, K.; Grabiec, M.; Pellerin, S.

2012-08-01

119

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

120

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

SciTech Connect

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

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

2011-06-01

121

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

122

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

PubMed Central

Background Numerous interactions between the coagulation and complement systems have been shown. Recently, links between coagulation and mannan-binding lectin-associated serine protease-1 (MASP-1) of the complement lectin pathway have been proposed. Our aim was to investigate MASP-1 activation of factor XIII (FXIII), fibrinogen, prothrombin, and thrombin-activatable fibrinolysis inhibitor (TAFI) in plasma-based systems, and to analyse effects of MASP-1 on plasma clot formation, structure and lysis. Methodology/Principal Findings We used a FXIII incorporation assay and specific assays to measure the activation products prothrombin fragment F1+2, fibrinopeptide A (FPA), and activated TAFI (TAFIa). Clot formation and lysis were assessed by turbidimetric assay. Clot structure was studied by scanning electron microscopy. MASP-1 activated FXIII and, contrary to thrombin, induced FXIII activity faster in the Val34 than the Leu34 variant. MASP-1-dependent generation of F1+2, FPA and TAFIa showed a dose-dependent response in normal citrated plasma (NCP), albeit MASP-1 was much less efficient than FXa or thrombin. MASP-1 activation of prothrombin and TAFI cleavage were confirmed in purified systems. No FPA generation was observed in prothrombin-depleted plasma. MASP-1 induced clot formation in NCP, affected clot structure, and prolonged clot lysis. Conclusions/Significance We show that MASP-1 interacts with plasma clot formation on different levels and influences fibrin structure. Although MASP-1-induced fibrin formation is thrombin-dependent, MASP-1 directly activates prothrombin, FXIII and TAFI. We suggest that MASP-1, in concerted action with other complement and coagulation proteins, may play a role in fibrin clot formation. PMID:22536427

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

2012-01-01

123

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

SciTech Connect

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

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

1993-04-01

124

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

SciTech Connect

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

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

1993-01-01

125

Observation of collisionless heating of low energy electrons in low pressure inductively coupled argon plasmas  

SciTech Connect

Collisionless heating of low energy electrons was observed in low pressure argon rf-biased inductively coupled plasmas (ICPs) by measurement of the electron energy distribution function (EEDF). When only capacitive power (bias) was supplied, the EEDF in the discharge was a bi-Maxwellian distribution with two electron groups. It was found that the low energy electrons were heated up significantly even with a little inductive power (<20 W) even when the discharge was in E mode. Due to the low gas pressure and low temperature of low energy electrons (close to the energy of the Ramsauer minimum), the collisional heating of low energy electrons appears to be negligible. Therefore, this effective heating of the low energy electrons showed a direct experimental evidence of the collisionless heating by inductive field. The significant heating of low energy electrons in E mode indicates that collisionless heating in the skin layer is an important electron heating mechanism of low pressure ICP even when the discharge is in E mode.

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

2008-12-08

126

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

NASA Astrophysics Data System (ADS)

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/O2(2%) to Ar/O2(2%)/N2(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, 1O2, OH, NO, H2O2, O3, and NO3-/NO2- as well as Cu+/Cu2+. The S. aureus inactivation results indicate that atomic oxygen (O) is the key inactivation agent, while other species play a lesser role in the inactivation progress studied here.

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

2012-06-01

127

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

SciTech Connect

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

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

2012-06-15

128

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

129

Time-resolved ion density determination by electrical current measurements in an atmospheric-pressure argon plasma  

NASA Astrophysics Data System (ADS)

High-resolution current signal measurements of a self-pulsing transient spark discharge revealed oscillations in the pulse decay phase. These oscillations appear with decreasing frequency between 250 MHz and 50 MHz for a specific gas flow range. The frequencies are well within the range of the plasma ion frequency. Consequently, ion acoustic waves are discussed as a possible reason. Considering molecular argon ions as the dominant ion, densities are found to decrease from n_{Ar_2^+}=10^{14}\\ \\text{cm}^{-3} to 4\\cdot10^{12}\\ \\text{cm}^{-3} . Evaluation of the plasma ion frequency creates a new possibility to determine ion densities.

Gerling, T.; Bussiahn, R.; Wilke, C.; Weltmann, K.-D.

2014-01-01

130

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

NASA Astrophysics Data System (ADS)

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

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

1988-09-01

131

Surface modification by argon plasma treatment improves antioxidant defense ability of CHO-k1 cells on titanium surfaces.  

PubMed

Titanium is one of the most used materials in implants and changes in its surface can modify the cellular functional response to better implant fixation. An argon plasma treatment generates a surface with improved mechanical proprieties without modifying its chemical composition. Oxidative stress induced by biomaterials is considered one of the major causes of implant failure and studies in this field are fundamental to evaluate the biocompatibility of a new material. Therefore, in this work, induction of oxidative stress by titanium surfaces subjected to plasma treatment (PTTS) was evaluated. The viability of CHO-k1 cells was higher on PTTS discs. Cells grown on titanium surfaces are subjected to intracellular oxidative stress. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular survival. These were associated with improved cellular antioxidant response in Plasma Treated Titanium Surface (PTTS). Furthermore, a decrease in protein and DNA oxidative damage was observed on cells grown on the roughed surface when compared to the smooth one. In conclusion, our data suggest that the treatment of titanium with argon plasma may improve its biocompatible, thus improving its performance as implants or as a scaffold in tissue engineering. PMID:24296152

de Queiroz, Jana Dara Freires; Leal, Angélica Maria de Sousa; Terada, Maysa; Agnez-Lima, Lucymara Fassarela; Costa, Isolda; Pinto, Nadja Cristhina de Souza; de Medeiros, Silvia Regina Batistuzzo

2014-04-01

132

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

SciTech Connect

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

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

2011-02-15

133

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

134

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

Microsoft Academic Search

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

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

2004-01-01

135

Surface roughening of silicon, thermal silicon dioxide, and low-k dielectric coral films in argon plasma  

SciTech Connect

The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO{sub 2}), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followed the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide.

Yin Yunpeng; Sawin, Herbert H. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2008-01-15

136

Investigations of a New Microwave Plasma Source Operating with Air, N2, CO2 and Argon Gases  

NASA Astrophysics Data System (ADS)

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 N2+ 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 equi- librium.

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

2011-08-01

137

Halftoning band gap of InAs/InP quantum dots using inductively coupled argon plasma-enhanced intermixing  

SciTech Connect

Inductively coupled argon plasma-enhanced intermixing of InAs/InP quantum dots grown on InP substrate is investigated. Intermixing is promoted by the near-surface defects generated by plasma exposure in annealing at a temperature of 600 deg. C for 30 s. The annealing results in a maximum differential band-gap blueshift of 106 nm but a thermal shift of only 10 nm. Band-gap halftones are obtained by controlling the amount of near-surface defects via wet chemical etching on the plasma-exposed InP cap layer. No degradation of quantum-dot crystal quality due to the process has been observed as evidenced by photoluminescence intensity.

Nie, D.; Mei, T.; Xu, C. D.; Dong, J. R. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Institute of Material Research and Engineering, Singapore 117602 (Singapore)

2006-09-25

138

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

139

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

E-print Network

was used in all of the tests. The results of the experiment showed that about 40g of the energy was lost to the anode and about 4't was lost to the cathode. French and Muntz (6) used a commercially made plasma jet consisting of a thoriated tungsten... orifice as an anode and a thoriated tungsten rod as a cathode. A power supply of 25 KW produced temperatures in argon approaching 10, 000 K. The flow through the 0. 3-inch diameter orifice was varied from 0. 5 lb per hr to 2. 0 lb per hr. The arc...

Farquhar, Bannister Wells

2012-06-07

140

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

PubMed

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

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

2014-02-20

141

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

PubMed

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

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

2012-06-10

142

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

NASA Astrophysics Data System (ADS)

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

Meyer, Gerhard; Seltzer, Michael D.

1999-02-01

143

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

USGS Publications Warehouse

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

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

1978-01-01

144

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

PubMed

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

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

2014-06-10

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

146

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

USGS Publications Warehouse

Inductively coupled argon plasma/optical emission spectrometery (ICAP/OES) is useful as a simultaneous, multielement analytical technique for the determination of trace elements in geological materials. A method for the determination of trace-level rare earth elements (REE) in geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved by a nitric acid gradient cation exchange and hydrochloric acid anion exchange. Precision of 1-4% relative standard deviation and comparable accuracy are demonstrated by the triplicate analysis of three splits of BCR-1 and BHVO-1. Analyses of other geological materials including coals, soils, and rocks show comparable precision and accuracy.

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

1982-01-01

147

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

149

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

SciTech Connect

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

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

2010-10-15

150

Type of precursor and synthesis of silicon oxycarbide (SiOâC{sub y}H) thin films with a surfatron microwave oxygen\\/argon plasma  

Microsoft Academic Search

Siliconelike thin films (i.e., SiOâC{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

Agnieszka Walkiewicz-Pietrzykowska; J. P. Espinos; Agustin R. Gonzalez-Elipe

2006-01-01

151

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

SciTech Connect

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

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

2013-08-05

152

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

153

Spectral blueshifts in laser light scattered from argon-gas-cluster plasmas  

SciTech Connect

An experimental study is presented on scattering of laser light from argon gas clusters irradiated by multipicosecond Nd:glass laser pulses at moderate intensity of 10{sup 15} W/cm{sup 2}. Space-resolved side-scattered laser light has a predominantly blueshifted and broadened spectrum (up to {approx}8 nm). The scattered signal intensity and average blueshift exhibit a marked dependence on the backing pressure of the gas. The results are explained by self-phase modulation of the laser radiation due to changing polarizability as the heated clusters pass through resonance at 3 times the critical density during which intense absorption and scattering occurs. The observed blueshift may be useful in diagnostics of this important phase of laser-cluster interactions.

Singhal, H.; Arora, V.; Naik, P.A.; Gupta, P.D. [Laser Plasma Division, Centre for Advanced Technology, Indore 452013 (India)

2005-10-15

154

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

PubMed

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

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

2013-01-01

155

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

NASA Astrophysics Data System (ADS)

In this paper, a theoretical model is described and demonstrated that serves as a useful tool for understanding K-shell radiating Z-pinch plasma behavior. Such understanding requires a self-consistent solution to the complete nonlocal thermodynamic equilibrium kinetics and radiation transport in order to realistically model opacity effects and the high-temperature state of the plasma. For this purpose, we have incorporated into the MACH2 two-dimensional magnetohydrodynamic (MHD) code [R. E. Peterkin et al., J. Comput. Phys. 140, 148 (1998)] an equation of state, called the tabular collisional radiative equilibrium (TCRE) model [J. W. Thornhill et al., Phys. Plasmas 8, 3480 (2001)], that provides reasonable approximations to the plasma's opacity state. MACH2 with TCRE is applied toward analyzing the multidimensional implosion behavior that occurred in Decade Quad (DQ) [D. Price et al., Proceedings of the 12th IEEE Pulsed Power Conference, Monterey, CA, edited by C. Stallings and H. Kirbie (IEEE, New York, 1999), p. 489] argon gas puff experiments that employed a 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.

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

156

Plasma surface modification of aluminium alloy samples treated with argon discharge conditioning  

Microsoft Academic Search

Summary form only given. The study of change in surface properties of metals and their alloys under plasma processing has a wide range of applications. It affords range, flexibility, ease and accuracy of process control at low cost as compared to other techniques. All the applications of non-equilibrium plasmas involve processes like sputtering, etching, polymerization, surface modification, etc. It is

S. J. Karandikar; C. C. Samant; S. V. Gogawale

1999-01-01

157

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

NASA Astrophysics Data System (ADS)

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

Shigeta, Masaya

2012-10-01

158

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

SciTech Connect

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

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

2011-06-15

159

New BRP for human plasma calibrated for coagulation factors V, VIII, XI and XIII - collaborative study for establishment of batches 1 and 2.  

PubMed

A human plasma reference preparation in International Units (IU) must be used in each potency assay of the human coagulation factors V, VIII and XI in human plasma pooled and treated for virus inactivation, according to the European Pharmacopoeia (Ph. Eur.) monograph 1646 and general chapters 2.7.4 and 2.7.22 respectively, and in the potency assay of human coagulation factor XIII in fibrin sealant kits, according to Ph. Eur. monograph 0903. International reference standards for all of these factors are now established, however, regional reference standards were not available for the required routine use. It was therefore proposed by European OMCLs and manufacturers to establish a European reference preparation, and it was the goal of this study to accomplish that. Two candidate biological reference preparations (BRPs), separate lyophilisation lots of the same normal human plasma bulk material, were calibrated against the International Standards (ISs) for human coagulation factors V, VIII, XI and XIII. Twelve European laboratories including OMCLs and manufacturers participated. The candidate material was tested against the ISs in 4 separate assays for each factor using the methods described in the relevant Ph. Eur. monographs and general chapters. No discernable difference was noted between the activities of the 2 candidates. They were shown to be suitable for their intended use and it was recommended to assign to both batches a potency of 0.73 IU/mL for factor V, 0.74 IU/mL for factor VIII, 0.59 IU/mL for factor XI and 0.79 IU/mL for factor XIII. Candidate batch B is proposed to be used first as lot 1, followed upon its depletion by candidate batch A (lot 2). The BRP batches will be monitored regularly for potency throughout their lifetime. EDQM BRP batches 1 and 2 of coagulation factors V, VIII, XI and XIII plasma were formally adopted by the Ph. Eur. Commission at their session in June 2011. PMID:22225765

Bayer, P; Daas, A; Milne, C

2011-11-01

160

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

SciTech Connect

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

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

1985-01-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

162

Numerical simulation study on fluid dynamics of plasma window using argon  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

163

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

PubMed

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

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

2014-01-01

164

Numerical simulation study on fluid dynamics of plasma window using argon  

SciTech Connect

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

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

2013-07-15

165

Experimental and simulated argon spectra in the 2.3-3.4 nm region from tokamak plasmas  

NASA Astrophysics Data System (ADS)

Experimental argon spectra in the 2.3-3.4 nm region from the Jet tokamak on a single null divertor configuration have been simulated. The spectra include lines from five ionization states, namely from Ar15+ Li-like to Ar11+ N-like ions. Collisional-radiative models have been constructed for these five Ar ions, considering electron collisional excitation and radiative decay as the populating processes of the excited states. These models give photon emission coefficients for the emitted lines at electron density and temperature values corresponding to the experimental situations. Impurity modelling is performed using a one-dimensional (1D) impurity transport code, calculating the steady-state radial distribution of the Ar ions. The Ar line brightnesses are evaluated in a post-processing subroutine and simulated spectra are obtained. The parts of the spectra corresponding to a single-ionization state do not depend on the experimental conditions and show good agreement except for the amplitude of the simulated 2s-3p Ar XVI line and the shape of the simulated 2.50 nm feature (composed of Ar XVI and Ar XV lines). On the other hand, the superposition of these spectra depends on the experimental conditions, as a consequence of the fact that the ion charge distribution depends not only on the radial profiles of the electron density and temperature, but also of the impurity transport coefficients. Simulations of the Ar spectra (including transport) give confidence in the atomic physics calculations; moreover, they allow the determination of the transport coefficients in the plasma region emitting the considered ionization states, i.e. at the interior of the last closed magnetic surface (LCMS). For a correct simulation of the amplitudes of the spectral features it is necessary to include a transport barrier inside the LCMS. As far as the atomic physics is concerned, we report improved wavelengths for Ar XV transitions and we benchmark photon emission coefficients for XUV transitions in highly ionized argon.

Mattioli, M.; Fournier, K. B.; Carraro, L.; Coffey, I.; Giroud, C.; Lawson, K.; Monier-Garbet, P.; O'Mullane, M.; Ongena, J.; Puiatti, M. E.; Sattin, F.; Scarin, P.; Valisa, M.

2001-01-01

166

Diagnostics and modeling of an argon\\/helium plasma spray process  

Microsoft Academic Search

The natural instability of the are in direct current (DC) plasma torches used in spray processing is one of the most important\\u000a causes for variations in heating of sprayed particles, leading to inconsistencies in the final coating quality. A relatively\\u000a simple diagnostic system has been set up to monitor the plasma jet instability, as well as some important process characteristics.

Z. Duan; J. Heberlein; L. Beall; J. Schein; M. Stachowicz

2000-01-01

167

Radical excitation temperatures and electron number densities in a 9, 27 and 50 MHz inductively-coupled argon plasma  

NASA Astrophysics Data System (ADS)

This work is the result of experiments performed on a 9, 27 and 50 MHz atmospheric pressure argon ICP uing the same thermometric species and instrumentation. Radiation originating from plasma volume with 0.25 mm 2 projected areas were measured. The lateral observed spatially integrated radiances were transformed to radial functions by using Abel integral equations. Variations of radiances from Ca atom and ion transitions as function of observation height were studied. Two ion transitions of Ca with sufficient excitation energy difference were chosen for two-line temperature determinations, while substitution of atom to ion radiance ratios into the Saha equation were used in calculating values for the electron number density. The cooling effect of the central penetrating nebulizer gas on the plasma centres was clearly observed through a decrease in the excitation temperatures at the lowest observation heights above the r.f. coils. Experimental evidence indicates a general decrease in excitation temperature with increasing generator frequency. The same tendency was observed for the electron number density. These phenomena are probably due to the variation in skin depth at the different frequencies.

Gunter, W. H.; Visser, K.; Zeeman, P. B.

168

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

169

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

170

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

SciTech Connect

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

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

2012-01-15

171

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

PubMed

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

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

2002-07-01

172

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

SciTech Connect

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

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

1988-06-01

173

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

SciTech Connect

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.

Despiau-Pujo, Emilie; Chabert, Pascal; Ramos, Raphaeel; Cunge, Gilles; Sadeghi, Nader [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau (France); Laboratoire des Technologies de la Microelectronique, CNRS, 38054 Grenoble (France)

2009-03-15

174

The influences of nitrogen, helium, hydrogen, or argon dilution on plasma-enhanced chemical vapor deposited a-SiNx:H  

Microsoft Academic Search

The effects of dilution gases on hydrogenated amorphous silicon nitride (a-SiN,:H) films were investigated in this study. Silane and ammonia were used as the reactive species, while nitrogen, helium, hydrogen, and argon were used as the dilution gases in a plasma enhanced chemical vapor deposition system at a substrate temperature of 300OC. The total hydrogen concentrations for all a-SiN,:H films

Chun-Yen Chang; Shou-Wei Hsieh; Yeong-Shyang Lee; Chiung-Wei Lin

1994-01-01

175

Temporal Evolution of Excited Level Populations in a High-Velocity Argon Plasma Flow  

NASA Astrophysics Data System (ADS)

A simplified collisional-radiative model is applied to a high velocity plasma flow through the arcjet nozzle to investigate the temporal evolution of excited level population densities in the selected spatial positions inside arcjet thruster. Computations are carried out for various sets of input parameters such as electron temperature, electron number density, atom temperature, and pressure. The numerical results illustrate that the extent of the ionization-recombination non-equilibrium is strongly dependent on the electron temperature and pressure, and is significantly affected by resonance radiation.

Sun, Su-Rong; Wang, Hai-Xing

2014-09-01

176

Argon/UF6 plasma experiments: UF6 regeneration and product analysis  

NASA Technical Reports Server (NTRS)

An experimental and analytical investigation was conducted to aid in developing some of the technology necessary for designing a self-critical fissioning uranium plasma core reactors (PCR). This technology is applicable to gaseous uranium hexafluoride nuclear-pumped laser systems. The principal equipment used included 1.2 MW RF induction heater, a d.c. plasma torch, a uranium tetrafluoride feeder system, and batch-type fluorine/UF6 regeneration systems. Overall objectives were to continue to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure, gaseous UF6; and to continue development of complementary diagnostic instrumentation and measurement techniques to characterize the effluent exhaust gases and residue deposited on the test chamber and exhaust system components. Specific objectives include: a development of a batch-type UF6 regeneration system employing pure high-temperature fluorine; development of a ruggedized time-of-flight mass spectrometer and associated data acquisition system capable of making on-line concentration measurements of the volatile effluent exhaust gas species in a high RF environment and corrosive environment of UF6 and related halide compounds.

Roman, W. C.

1980-01-01

177

Phenol decomposition by pulsed-plasma exposure in oxygen and argon atmosphere  

NASA Astrophysics Data System (ADS)

Phenol in an aqueous solution is decomposed by the exposure of pulsed-discharge plasma, and by-products are investigated by gas chromatograph mass spectrometry. When Ar is used as a background gas, catechol, hydroquinone and 4-hydroxy-2-cyclohexene-1-on are produced, and no O3 is produced; therefore, OH radicals generated in the plasma can initiate the decomposition of phenol, and 4-hydroxy-2-cyclohexene-1-on can be produced. Further, 4-hydroxy-2-cyclohexene-1-on can be converted into catechol and hydroquinone. When O2 is used as a background gas, catechol, hydroquinone, formic acid, maleic acid, succinic acid and 4,6-dihydroxy-2,4-hexadienoic acid are produced. Therefore, phenol is probably decomposed into 4,6-dihydroxy-2,4-hexadienoic acid by 1,3-dipolar addition reaction with O3, and 4,6-dihydroxy-2,4-hexadienoic acid can be decomposed into maleic acid and succinic acid by 1,3-dipolar addition reaction with O3. Oxalic acid is possibly another by-product from 4,6-dihydroxy-2,4-hexadienoic acid, since formic acid, which is produced from oxalic acid, is detected.

Satoh, Kohki; Shiota, Haruki; Itabashi, Hideyuki; Itoh, Hidenori

2011-11-01

178

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

SciTech Connect

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

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

1995-08-01

179

The spatially resolved measurements of the atomic densities in argon Paschen 1s levels by OES in a capacitively coupled plasma  

NASA Astrophysics Data System (ADS)

Spatially resolved atomic densities of argon 1s levels in a capacitively coupled plasma are measured by using an OES branching fraction method with the mono-directional escape factor. Different spatial profiles of the densities of the metastable and resonance levels are observed. The resonance levels increase more drastically than the metastable levels with the distance from the power electrode in the sheath, while in the bulk plasma, both resonance and metastable levels are more uniform. The relationship between the distribution of the electron density and those of the metastable and the resonance levels is also discussed.

Li, Jiang; Liu, Fei-Xiang; Zhu, Xi-Ming; Pu, Yi-Kang

2011-07-01

180

Dynamics of the spectral behaviour of an ultrashort laser pulse in an argon-gas-filled capillary discharge-preformed plasma channel  

NASA Astrophysics Data System (ADS)

We have reported the argon plasma waveguide produced in an alumina (Al2O3) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 1016 W/cm2. A one-dimensional magnetohydrodynamic (MHD) code was used to evaluate the average degree of ionization of Ar in the preformed plasma channel. The spectrum of the propagated laser pulse in the Ar plasma waveguide was not modified and was well reproduced by a particle-in-cell (PIC) simulation under initial ion charge state of Ar3+ in the preformed plasma waveguide. The optimum timing for the laser pulse injection was around 150 ns after initiation of a discharge with a peak current of 200 A.

Sakai, S.; Higashiguchi, T.; Yugami, N.; Bobrova, N.; Sentoku, Y.; Kodama, R.

2013-11-01

181

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

NASA Astrophysics Data System (ADS)

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

Phillips, Hugh Alan

1988-12-01

182

Changes in Plasma Levels of Natural Anticoagulants in Disseminated Intravascular Coagulation: High Prognostic Value of Antithrombin and Protein C in Patients with Underlying Sepsis or Severe Infection  

PubMed Central

Background Dysfunctional natural anticoagulant systems enhance intravascular fibrin for mation in disseminated intravascular coagulation (DIC), and plasma levels of natural anti coagulants can be used in the diagnosis and prognosis of DIC. Herein, the diagnostic value of 4 natural anticoagulants was assessed, and the prognostic value of antithrombin and protein C were validated in a large population. Methods Part 1 study included 126 patients with clinically suspected DIC and estimated plasma levels of 4 candidate anticoagulant proteins: antithrombin, protein C, protein S, and protein Z. Part 2 comprised 1,846 patients, in whom plasma antithrombin and protein C levels were compared with other well-known DIC markers according to the underlying dis eases. The 28-day mortality rate was used to assess prognostic outcome. Results Antithrombin and protein C showed higher areas under the ROC curve than pro tein S and protein Z. In part 2 of the study, antithrombin and protein C levels significantly correlated with DIC score, suggesting that these factors are good indicators of DIC severity. Antithrombin and protein C showed significant prognostic power in Kaplan-Meier analyses. In patients with sepsis/severe infection, antithrombin and protein C showed higher hazard ratios than D-dimer. Platelet count showed the highest hazard ratio in patients with hemato logic malignancy. In patients with liver disease, the hazard ratio for antithrombin levels was significantly high. Conclusions Decreased plasma anticoagulant levels reflect florid consumption of the phys iologic defense system against DIC-induced hypercoagulation. Plasma antithrombin and protein C levels are powerful prognostic markers of DIC, especially in patients with sepsis/severe infection. PMID:24624342

Choi, Qute; Hong, Ki Ho; Kim, Ji-Eun

2014-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

185

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

Microsoft Academic Search

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

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

2003-01-01

186

Recombinations in the decay of argon plasma jet surrounded by Ar, He, N2, and H2 gases  

Microsoft Academic Search

The paper describes a laminar plasmajet ejected into several types of coaxial gas flows at low pressure. The decay of centerline temperature and mole fraction are measured, and the recombination reaction in the plasmajet is investigated. Experimental equipment and theoretical procedures are described. Exact numerical solutions were calculated for an argon coaxial flow, and less precise similarity solutions were obtained

T. Honda; A. Kanzawa

1977-01-01

187

Systems Biology of Coagulation  

PubMed Central

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

Diamond, Scott L.

2013-01-01

188

Temperature measurement in an argon jet  

Microsoft Academic Search

A short review is given of spectroscopic temperature measurements in ; argon plasma jets. Two regions were observed in the jet, a bright core and a far ; less radiating outer zone. In the spectrum of the core, continuous radiation and ; neutral argon lines are present. The broadening of the lines decreases rapidly ; in the passage to the

Slechta

1973-01-01

189

Surface force measurements between titanium dioxide surfaces prepared by atomic layer deposition in electrolyte solutions reveal non-DLVO interactions: influence of water and argon plasma cleaning.  

PubMed

Surface force measurements between titania surfaces in electrolyte solutions have previously revealed an unexplained long-range repulsive force at high pH, not described by Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory. Here, the surface forces between titania surfaces produced by atomic layer deposition (ALD) and cleaned using a variety of methods have been measured to determine the influence of the cleaning protocol on the measured forces and test the hypothesis that water plasma cleaning of the surface results in non-DLVO forces at high pH. For argon plasma and water plasma cleaned surfaces, a diffuse double layer repulsion and van der Waals attraction is observed near the isoelectric point. At high pH, the force remained repulsive up until contact, and no van der Waals attraction or adhesion was observed. Differences in the measured forces are explained by modification of the surface chemistry during cleaning, which alters the density of charged groups on the surface, but this cannot explain the observed disagreement with DLVO theory at high pH. PMID:24548170

Walsh, Rick B; Evans, Drew; Craig, Vincent S J

2014-03-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

191

Rethinking the coagulation cascade.  

PubMed

The concept of coagulation as a "cascade" of proteolytic reactions was a conceptual breakthrough in understanding how the coagulation process acts as a biologic amplifier. The model that it evolved into, with "extrinsic" and "intrinsic" pathways meeting in a common pathway, delineates the interactions between the coagulation proteins and provides a framework for interpreting the common screening coagulation tests. The coagulation "cascade" has significant limitations as a model of how hemostasis occurs in vivo, however. This article describes how the modern view of hemostasis has evolved to emphasize the role of cells in controlling and directing the coagulation reactions. It also highlights how host factors that are not part of the coagulation process per se can influence the effectiveness of coagulation. PMID:16131441

Hoffman, Maureane M; Monroe, Dougald M

2005-09-01

192

Nonmetals in the argon-inductively coupled plasma-optical emission spectrometry: I. Phosphorus, sulfur and carbon.  

PubMed

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

Knauthe, B; Otto, M

2001-12-01

193

Bustling argon: biological effect  

PubMed Central

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

2013-01-01

194

Bustling argon: biological effect.  

PubMed

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

Ye, Zhouheng; Zhang, Rongjia; Sun, Xuejun

2013-01-01

195

Atmospheric-pressure argon plasma etching of spin-coated 3,4-polyethylenedioxythiophene:polystyrenesulfonic acid (PEDOT:PSS) films for cupper phtalocyanine (CuPc)\\/C 60 heterojunction thin-film solar cells  

Microsoft Academic Search

Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated 3,4-polyethylenedioxythiophene:polystyrenesulfonic acid (PEDOT:PSS) films were investigated by real-time characterization by the spectroscopic ellipsometry (SE) during argon plasma etching at atmospheric pressure. Spectral analysis revealed that homogeneous etching occurred within 10–15nm of the top surface, followed by the appearance of a conductive PEDOT phase and surface roughning, which

Tomohisa Ino; Tatsuya Hayashi; Keiji Ueno; Hajime Shirai

2011-01-01

196

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

SciTech Connect

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

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

2013-04-14

197

Phenol Decomposition Process by Pulsed-discharge Plasma above a Water Surface in Oxygen and Argon Atmosphere  

NASA Astrophysics Data System (ADS)

By-products from phenol by the exposure of pulsed-discharge plasma above a phenol aqueous solution are investigated by gas chromatography mass spectrometry, and the decomposition process of phenol is deduced. When Ar is used as a background gas, catechol, hydroquinone and 4-hydroxy-2-cyclohexene-1-on are produced, and no O3 is detected; therefore, active species such as OH, O, HO2, H2O2, which are produced from H2O in the discharge, can convert phenol into those by-products. When O2 is used as a background gas, formic acid, maleic acid, succinic acid and 4,6-dihydroxy-2,4-hexadienoic acid are produced in addition to catechol and hydroquinone. O3 is produced in the discharge plasma, so that phenol is probably decomposed into 4,6-dihydroxy-2,4-hexadienoic acid by 1,3-dipolar addition reaction with O3, and then 4,6-dihydroxy-2,4-hexadienoic acid can be decomposed into formic acid, maleic acid and succinic acid by 1,3-dipolar addition reaction with O3.

Shiota, Haruki; Itabashi, Hideyuki; Satoh, Kohki; Itoh, Hidenori

198

International reference standards in coagulation.  

PubMed

Measurement of coagulation factor activity using absolute physico-chemical techniques is not possible and estimation therefore relies on comparative bioassay relative to a reference standard with a known or assigned potency. However the inherent variability of locally prepared and calibrated reference standards can give rise to poor agreement between laboratories and methods. Harmonisation of measurement between laboratories at the international level relies on the availability of a common source of calibration for local reference standards and this is provided by the World Health Organization (WHO) International Standards which define the International Unit for the analyte. This article describes the principles, practices and problems of biological standardisation and the development and use of reference standards for assays of coagulation factors, with particular emphasis on WHO International Standards for both concentrates and plasma. PMID:20338786

Raut, Sanj; Hubbard, Anthony R

2010-07-01

199

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

NASA Astrophysics Data System (ADS)

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

Major, Helen E.

200

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

SciTech Connect

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

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

1984-02-01

201

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

202

Spatial localization of bacteria controls coagulation of human blood by `quorum acting'  

E-print Network

Spatial localization of bacteria controls coagulation of human blood by `quorum acting' Christian J1 Blood coagulation often accompanies bacterial infections and sepsis and is generally accepted of bacteria substantially affects coagulation of human and mouse blood and plasma. Bacillus cereus

Ismagilov, Rustem F.

203

Excimer emission from microhollow cathode argon discharges  

NASA Astrophysics Data System (ADS)

Microhollow cathode discharges (MHCDs) operated in rare gases are sources of intense excimer emission. Of particular interest is argon, because of its relatively low cost and the short wavelength (128 nm) of its excimer emission. The measured internal efficiency, obtained in static argon at atmospheric pressure, was found to be on the order of 1%. Flowing argon through a direct current (DC) MHCD at atmospheric pressure caused the argon excimer internal efficiency to increase to 6%, indicating that the low efficiency in static argon is mainly due to impurities. Applying 10 ns pulses to the DC plasma resulted in an increase in excimer power from 30 mW DC to 180 mW peak power, at an efficiency of 5-6%. The increase in excimer power correlates with an increase in the electron density. For DC operation, electron densities of 1015 cm-3 were measured in atmospheric pressure argon micro-plasmas, which increased to values beyond 1016 cm-3 for nanosecond pulsed operation. This increase in electron density and excimer power is due to pulsed electron heating, an effect that has allowed us to raise the mean electron energy from 1 eV, for DC operation, to 2.25 eV in the pulsed mode.

Moselhy, Mohamed; Petzenhauser, Isfried; Frank, Klaus; Schoenbach, Karl H.

2003-12-01

204

Depth Profile Characterization of Spin-Coated Poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonic acid) Films for Thin-Film Solar Cells during Argon Plasma Etching by Spectroscopic Ellipsometry  

NASA Astrophysics Data System (ADS)

Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films were investigated by real-time characterization by spectroscopic ellipsometry (SE) during argon plasma etching at atmospheric pressure. Spectral analysis revealed that homogeneous etching occurred within 10-15 nm of the top surface, followed by the appearance of a conductive PEDOT phase and surface roughening, which originated from the depth profile of the PEDOT-to-PSS molar concentration ratio. The use of the plasma-etched PEDOT:PSS layer relatively improved the performance of the cupper phthalocyanine (CuPc)/C60 organic thin-films solar cells as a hole-transport layer with higher optical transmittance by adjusting the plasma etching condition.

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

2011-08-01

205

Coagulation and Mental Disorders  

PubMed Central

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

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

2014-01-01

206

Cytochemical studies on pathological Mueller cells after argon laser photocoagulation  

SciTech Connect

The cytochemical localization of G6Pase activity, which is specific to the endoplasmic reticulum (ER) of Mueller cells, was studied after argon laser photocoagulation in the guinea pig retina. After argon laser radiation, Mueller cells exhibited enlargement of the cytoplasm, an increase of reactive ER and the nuclei, dislocation of the nuclei and diagonal stretching of the cytoplasm. However, cell attachment between Mueller cells and the proliferated pigment epithelial cells or Bruch's membrane differed with the degree of retinal coagulation. This histo- and cytochemical method may be useful for examining Mueller cells under various pathological conditions.

Ishigooka, H.; Hirata, A.; Kitaoka, T.; Ueno, S.

1989-03-01

207

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

NASA Technical Reports Server (NTRS)

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

Roman, W. C.

1979-01-01

208

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

Microsoft Academic Search

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

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

209

Coagulation Studies in Severe Birth Asphyxia  

PubMed Central

Coagulation studies have been performed in 9 infants who were so severely asphyxiated at birth as to require assisted ventilation for at least 10 minutes. Four of the infants died, though none suffered from any bleeding tendency in life. In 2 fatal cases and 1 survivor the laboratory findings of circulating fibrin degradation products, low plasma fibrinogen, and low or rising platelet count indicated that disseminated intravascular coagulation had occurred in the first few hours of life. Fibrin thromboemboli were found in the liver and adrenals of the 2 such babies that died. One baby had a low level of vitamin K dependent factors associated with fetal growth retardation. Clinical factors common to the cases with evidence of disseminated intravascular coagulation were the need for mechanical ventilation, and the occurrence of hypothermia. Though haemostatic failure due to disseminated intravascular coagulation is likely to develop only in a small minority of birth asphyxiated infants, the possibility should be considered in any that become hypothermic within a few hours of birth. PMID:5090658

Chessells, J. M.; Wigglesworth, J. S.

1971-01-01

210

Coagulation monitor based on serum migration through absorbent materials  

Microsoft Academic Search

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

Paul E. Wilson

211

Glial reactions to argon laser photocoagulation injury in rabbit and rat retinas  

Microsoft Academic Search

Argon laser photocoagulation is a standard and effective clinical technique for a variety of disease conditions. However there is evidence that coagulation produces more widespread alterations in the retina than the local scarring at the injury site. For example, in diabetic retinopathy multiple photocoagulations in the retinal periphery can control blood vessel growth in the central retina. Therefore we have

Martin F. Humphrey; Yi Chu; Claudia Sharp; Stephen Moore; Krishna Mann; Piroska Rakoczy; Ian J. Constable

1996-01-01

212

Thermophysical properties of argon  

SciTech Connect

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

Jaques, A.

1988-02-01

213

Excimer Emission from Argon Microhollow Cathode Discharges  

NASA Astrophysics Data System (ADS)

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

Moselhy, Mohamed; Schoenbach, Karl H.

2002-10-01

214

Thermal equilibrium in argon induction discharges  

Microsoft Academic Search

The equilibrium state of induction discharge plasmas in argon has been examined for a wide range of pressures (7·6 to 760 Torr) and with electron densities ranging from 3×1014 to 8×1015 cm?3. Grossly non-thermal conditions are obtained when the electron density falls below 1015 cm?3. For higher densities the approach to LTE (local thermal equilibrium) depends on the strength of

A D Stokes

1971-01-01

215

Thermophoretically dominated aerosol coagulation.  

PubMed

A theory of aerosol coagulation due to size-dependent thermophoresis is presented. This previously overlooked effect is important when local temperature gradients are large, the sol population is composed of particles of much greater thermal conductivity than the carrier gas, with mean diameters much greater than the prevailing gas mean free path, and an adequate "spread" in sizes (as in metallurgical mists or fumes). We illustrate this via a population-balance analysis of the evolution of an initially log-normal distribution when this mechanism dominates ordinary Brownian diffusion. PMID:21231753

Rosner, Daniel E; Arias-Zugasti, Manuel

2011-01-01

216

Spectroscopic characterization of femtosecond laser filament in argon gas  

SciTech Connect

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

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

2007-08-01

217

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

PubMed

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

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

2013-12-01

218

Argon frost continuous cryopump for fusion applications  

SciTech Connect

A cryopumping system based on the snail continuous cryopump concept is being developed for fusion applications under a DOE SBIR grant. The primary pump is a liquid helium cooled compound pump designed to continuously pump and fractionate deuterium/tritium and helium. The D/T pumping stage is a 500 mm bore cryocondensation pump with a nominal pumping speed of 45,000 L/s. It will be continuously regenerated by a snail regeneration by head every 12 minutes. Continuous regeneration will dramatically reduce the vulnerable tritium inventory in a fusion reactor. Operating at an inlet pressure of 1 millitorr, eight of these pumps could pump the projected D/T flow in the ITER CDA design while reducing the inventory of tritium in the pumping system from 630 to 43 grams. The helium fraction will be pumped in a compound argon frost stage. This stage will also operate continuously with a snail regeneration head. In addition the argon spray head will be enclosed inside the snail, thereby removing gaseous argon from the process chamber. Since the cryocondensation stage will intercept over 90% of the D/T/H steam, a purified stream from this stage could be directly reinjected into the plasma as gas or pellets, thereby bypassing the isotope separation system and further simplifying the fuel cycle. Experiments were undertaken in Phase I which demonstrated continuous cryosorption pumping of hydrogen on CO{sub 2} and argon frosts. The pumping system and its relevance to fusion reactor pumping will be discussed.

Foster, C.A.; McCurdy, H.C.

1993-12-01

219

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

Microsoft Academic Search

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

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

220

The Solar Argon Abundance  

E-print Network

The solar argon abundance cannot be directly derived by spectroscopic observations of the solar photosphere. The solar Ar abundance is evaluated from solar wind measurements, nucleosynthetic arguments, observations of B stars, HII regions, planetary nebulae, and noble gas abundances measured in Jupiter's atmosphere. These data lead to a recommended argon abundance of N(Ar) = 91,200(+/-)23,700 (on a scale where Si = 10^6 atoms). The recommended abundance for the solar photosphere (on a scale where log N(H) = 12) is A(Ar)photo = 6.50(+/-)0.10, and taking element settling into account, the solar system (protosolar) abundance is A(Ar)solsys = 6.57(+/-)0.10.

Katharina Lodders

2007-10-24

221

Assessment of a chair-side argon-based non-thermal plasma treatment on the surface characteristics and integration of dental implants with textured surfaces.  

PubMed

The biomechanical effects of a non-thermal plasma (NTP) treatment, suitable for use in a dental office, on the surface character and integration of a textured dental implant surface in a beagle dog model were evaluated. The experiment compared a control treatment, which presented an alumina-blasted/acid-etched (AB/AE) surface, to two experimental treatments, in which the same AB/AE surface also received NTP treatment for a period of 20 or 60 s per implant quadrant (PLASMA 20' and PLASMA 60' groups, respectively). The surface of each specimen was characterized by electron microscopy and optical interferometry, and surface energy and surface chemistry were determined prior to and after plasma treatment. Two implants of each type were then placed at six bilateral locations in 6 dogs, and allowed to heal for 2 or 4 weeks. Following sacrifice, removal torque was evaluated as a function of animal, implant surface and time in vivo in a mixed model ANOVA. Compared to the CONTROL group, PLASMA 20' and 60' groups presented substantially higher surface energy levels, lower amounts of adsorbed C species and significantly higher torque levels (p=.001). Result indicated that the NTP treatment increased the surface energy and the biomechanical fixation of textured-surface dental implants at early times in vivo. PMID:22498282

Teixeira, Hellen S; Marin, Charles; Witek, Lukasz; Freitas, Amilcar; Silva, Nelson R F; Lilin, Thomas; Tovar, Nick; Janal, Malvin N; Coelho, Paulo G

2012-05-01

222

Blood Coagulation, Inflammation and Malaria  

PubMed Central

I. ABSTRACT Malaria remains a highly prevalent disease in more than 90 countries and accounts for at least 1 million deaths every year. Plasmodium falciparum infection is often associated with a procoagulant tonus characterized by thrombocytopenia and activation of the coagulation cascade and fibrinolytic system; however, bleeding and hemorrhage are uncommon events, suggesting that a compensated state of blood coagulation activation occurs in malaria. This article i) reviews the literature related to blood coagulation and malaria in a historic perspective, ii) describes basic mechanisms of coagulation, anticoagulation, and fibrinolysis, iii) explains the laboratory changes in acute and compensated disseminated intravascular coagulation (DIC), iv) discusses the implications of tissue factor (TF) expression in the endothelium of P. falciparum-infected patients, and v) emphasizes the pro-coagulant role of parasitized erythrocytes (pRBC) and activated platelets in the pathogenesis of malaria. This article also presents the ‘Tissue Factor Model’ (TFM) for malaria pathogenesis, which places TF as the interface between sequestration, endothelial cell activation, blood coagulation disorder and inflammation often associated with the disease. The relevance of the coagulation-inflammation cycle for the multiorgan dysfunction and coma is discussed in the context of malaria pathogenesis. PMID:18260002

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

2010-01-01

223

Global coagulation in myeloproliferative neoplasms.  

PubMed

In spite of their recognized risk of thrombosis, patients with myeloproliferative neoplasms (MPN) show little or no abnormalities of traditional coagulation tests, perhaps because these are unable to represent the balance between pro- and anticoagulants nor the effect of platelets and blood cells. We investigated whether global tests such as thrombin generation in platelet-rich plasma (PRP) or thromboelastometry in whole blood were able to detect signs of procoagulant imbalance in MPN. The endogenous thrombin potential (ETP) of 111 patients and 89 controls was measured in PRP with platelet count adjusted to the original patient- or control-count. Testing was performed with and without thrombomodulin (the physiological protein C activator) and results were expressed as ETP ratios (with/without thrombomodulin). High ETP ratios reflect resistance to thrombomodulin and were taken as indexes of procoagulant imbalance. Patients were also investigated by thromboelastometry that provides such parameters as the clot formation time (CFT) and maximal clot firmness (MCF). Short CFT or high MCF were taken as indexes of procoagulant imbalance. ETP ratios were higher in patients than in controls and were directly correlated with platelet counts and inversely with the plasma levels of free protein S, protein C and antithrombin. Patients on hydroxyurea had lower ETP ratios than those on other treatments. CFT was shorter and MCF was greater in patients than controls; CFT and MCF were correlated with platelet counts. In conclusion, patients with MPN display a procoagulant imbalance detectable by thrombin generation and thromboelastometry. These tests might be useful in the frame of clinical trials to assess their association with the occurrence of thrombosis and with the effect of therapeutic strategies in MPN. PMID:23820940

Tripodi, Armando; Chantarangkul, Veena; Gianniello, Francesca; Clerici, Marigrazia; Lemma, Laura; Padovan, Lidia; Gatti, Loredana; Mannucci, Pier Mannuccio; Peyvandi, Flora

2013-12-01

224

Understanding Coagulation Disorders  

NSDL National Science Digital Library

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

Braun, Mark

2009-11-30

225

Microfluidics and Coagulation Biology  

PubMed Central

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

Colace, Thomas V.; Tormoen, Garth W.

2014-01-01

226

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

SciTech Connect

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

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

2007-06-15

227

Thermophoretically modified aerosol brownian coagulation.  

PubMed

A theory of aerosol coagulation rates resulting from continuum-regime brownian coagulation in the presence of size-dependent particle thermophoresis is developed and explored here. We are motivated by a wide variety of applications in which particle brownian coagulation occurs in a nonisothermal gas where differential thermophoretic drift contributes to, but does not dominate, the encounter frequency between suspended spherical particles (e.g., mist droplets) of different sizes. We employ a Smoluchowski-like population-balance to demonstrate the relative roles of brownian diffusion and thermophoresis in shaping the short and long time (asymptotic or "coagulation-aged") mist-droplet size distribution (DSD) function. To carry out these combined-mechanism DSD-evolution calculations we developed a rational "coupled" coagulation rate constant (allowing for simultaneous brownian diffusion and relative thermophoretic drift) rather than simply adding the relevant individual coagulation "kernels." Dimensionless criteria are provided to facilitate precluding other coagulation mechanisms not considered here (such as simultaneous sedimentation or Marangoni-flow-induced mist-droplet phoresis) and potential complications not included in the present model [as finite-rate coalescence, initial departures from the continuum (Stokes drag-) limit, and even dense (nonideal) vapor effects]. PMID:21928988

Arias-Zugasti, Manuel; Rosner, Daniel E

2011-08-01

228

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

PubMed

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

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

2003-12-01

229

Argon ion pollution of the magnetosphere  

NASA Technical Reports Server (NTRS)

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

Lopez, R. E.

1985-01-01

230

Study of nuclear recoils in liquid argon with monoenergetic neutrons  

E-print Network

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

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

2012-01-01

231

Study of nuclear recoils in liquid argon with monoenergetic neutrons  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

232

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)

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.

Li, Guo-lu; Ma, Jian-long; Wang, Hai-dou; Kang, Jia-jie; Xu, Bin-shi

2014-08-01

233

Analysis of the limiting noise and identification of some factors that dictate the detection limits in a low-power inductively coupled argon plasma system  

NASA Astrophysics Data System (ADS)

The background signal defined as the output signal ( xB) of the photomultiplier and the relative standard deviation (RSD) of xB at the wavelengths of 36 prominent analysis lines in the 190-320 nm region were measured under ICP compromise conditions for simultaneous multi-element analysis using a monochromator with an experimental spectral bandwidth of 0.015 nm. The RSD was found to vary systematically with xB according to the theoretically expected relationship RSD = (? B2 + g?/ xB) 1/2 where ? B(?0.5%) is the constant source flicker noise contribution, g?/ xB the shot-noise contribution and g? a coefficient containing the photomultiplier (PMT) gain g. Dark current detector noise was negligible, at least in part, owing to the use of lock-in amplification. The validity of relationship (0) was tested for various types of PMT and for both pure aqueous solutions and solutions with 1 to 3% w/v amounts of either calcium chloride, sodium chloride, or a mixture of nickel and cobalt nitrates. Only in the case of the nickel-cobalt matrix were some departures found and these were attributable to line coincidences. Relationship (0) was found to apply also to net line signals, the flicker noise term, ? s, then being about 1% instead of 0.5% for the present ICP system. Detection limits for 36 prominent lines of the elements As, Au, B, Be, Bi, Ge, In, Mg, Mn, Ni, P, Pb, Sb, Se, Sn and Zn were computed on the basis of relationship (0) and measured signal-to-background ratios (SBR). The results permitted an assessment of the separate effects that SBR, source flicker noise and shot noise have on the detection limits and this facilitated a detailed comparison of the detection limits obtained in this work with those reported by Winge, Peterson and Fassel [ Appl. Spectrosc.33, 106 (1979)]. The measurements of detection limits were extended to solutions with matrices (calcium chloride, sodium chloride, and a mixture of nickel and cobalt nitrates) to test the validity of the conclusions drawn from experiments with pure aqueous solutions under less idealized analysis conditions and to provide some results obtained with a low-power argon ICP in the scope of the "ICP Detection Limits Program". These experiments included the measurement of the various quantities that may undergo an influence from the matrix, viz. background, net signal, SBR, and RSD of background signal. In this way it was possible not only to state the gross effect of the matrices on the detection limits, but also to give a quantitative account of the various sub-effects that were responsible for the gross effects. Since the calcium chloride matrix was included to assess the system for its stray light rejection characteristics, some experiments involving stray light elimination by a band rejection filter or a solar blind PMT were performed. A basic conclusion of this work is that the full exploitation of the important low ultraviolet wavelength region (190-250 nm) in ICP trace analysis requires the use of spectrometers with a high optical conductance, efficient entrance optics, and photomultipliers with high spectral sensitivity and low dark current noise. Only under such conditions can the "ideal" RSD of the background signal of 1% be realized, or at least approached, down to the lower end of the wavelength range, if one requires in addition that a reasonably high spectral resolution (e.g. 0.015 nm) be used to maximize the signal-to-background ratios and minimize spectral interferences.

Boumans, P. W. J. M.; McKenna, R. J.; Bosveld, M.

234

Whole blood coagulation analyzers.  

PubMed

Whole blood Coagulation analyzers (WBCAs) are widely used point-of-care (POC) testing devices found primarily in cardiothoracic surgical suites and cardia catheterization laboratories. Most of these devices can perform a number of coagulation tests that provide information about a patient's blood clotting status. Clinicians use the results of the WBCA tests, which are available minutes after applying a blood sample, primarily to monitor the effectiveness of heparin therapy--an anticoagulation therapy used during cardiopulmonary bypass (CPB) surgery, angioplasty, hemodialysis, and other clinical procedures. In this study we evaluated five WBCAs from four suppliers. Our testing focused on the applications for which WBCAs are primarily used: Monitoring moderate to high heparin levels, as would be required, for example, during CPB are angioplasty. For this function, WCBAs are typically used to perform an activated clotting time (ACT) test or, as one supplier refers to its test, a heparin management test (HMT). All models included in this study offered an ACT test or an HMT. Monitoring low heparin levels, as would be required, for example,during hemodialysis. For this function, WBCAs would normally be used to perform either a low-range ACT (LACT) test or a whole blood activated partial thromboplastin time (WBAPTT) test. Most of the evaluated units could perform at least one of these tests; one unit did not offer either test and was therefore not rated for this application. We rated and ranked each evaluated model separately for each of these two applications. In addition, we provided a combined rating and ranking that considers the units' appropriateness for performing both application. We based our conclusions on a unit's performance and humans factor design, as determined by our testing, and on its five-year life-cycle cost, as determined by our net present value (NPV) analysis. While we rated all evaluated units acceptable for each appropriate category, we did identify some significant differences that enabled us to rank the units in order of preference. We have included a Selection, Purchasing, and use guide at the end of this study to help facilities identify the unit that will best meet their needs. PMID:9283920

1997-08-01

235

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, ...

236

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

237

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

NASA Astrophysics Data System (ADS)

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

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

1994-05-01

238

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

PubMed

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

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

2014-05-01

239

Argon surface wave discharges at medium pressure. Experiments and discussion on the energy balance  

E-print Network

999 Argon surface wave discharges at medium pressure. Experiments and discussion on the energy recombinaison dissociative de Ai+2 au-dessus de 100 Torr. Abstract. 2014 Argon surface wave discharges, created. Generation and maintaining of long plasma columns by surface waves, from very low pressure (~100 mTorr) up

Paris-Sud XI, Université de

240

Thermophysical properties of multi-shock compressed dense argon.  

PubMed

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

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

2014-02-21

241

Thermophysical properties of multi-shock compressed dense argon  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

242

Depleted argon from underground sources  

SciTech Connect

Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic {sup 39}Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in {sup 39}Ar. In Cortez Colorado a CO{sub 2} well has been discovered to contain approximately 500ppm of argon as a contamination in the CO{sub 2}. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N{sub 2}, and He mixture, from the CO{sub 2} through chromatographic gas separation. The N{sub 2} and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.

Back, H.O.; /Princeton U.; Alton, A.; /Augustana U. Coll.; Calaprice, F.; Galbiati, C.; Goretti, A.; /Princeton U.; Kendziora, C.; /Fermilab; Loer, B.; /Princeton U.; Montanari, D.; /Fermilab; Mosteiro, P.; /Princeton U.; Pordes, S.; /Fermilab

2011-09-01

243

[Examination of the sample centrifugation time for emergency coagulation test].  

PubMed

The rapidity of coagulation testing is important for use as appropriate substitution therapy in patients with, or at risk of critical bleeding requiring massive transfusion. Whereas the ordinary method of coagulation testing is known to be slow, in a critically haemorrhaging patient, a rapid turnaround time of coagulation testing becomes indispensable. To find out if coagulation test results will be affected by a shortened centrifugation time, we measured PT (prothrombin time), APTT (activated partial thromboplastin time), FIB (fibrinogen) and PLT (platelet) in plasma, using different centrifugation times (10 min, 5 min, 3 min), and analyzed the measurements. We found that, whereas centrifugation time significantly affected the PLT count in plasma (10 min; 5.17 +/- 3.71 x 10(3)/microl, 5min; 28. +/- 26.9 x 10(3)/microl, 3min; 63.7 x 10(3)/microl), PT(10min; 14.6 +/- 5.76 sec, 5min; 14.7 +/- 5.84 sec, 3min; 14.9 +/- 6.40 sec), APTT (10min; 36.4 +/- 15.9 sec, 5min; 36.8 +/- 16.5 sec, 3min; 34.7 +/- 11.4 sec) and FIB(10min; 361 +/- 134 mg/dl, 5min; 356 +/- 132 mg/dl, 3min; 356 +/- 125 mg/dl) were not affected. These data suggest that shortening centrifugation time will have no significant effect on the value of PT, APTT and FIB, in an emergency situation. PMID:23383570

Watanabe, Yumi; Kawahara, Yoshie; Hanada, Daisuke; Nozawa, Keisuke; Tomoda, Yutaka; Kino, Shuichi

2012-11-01

244

Tissue Factor in Coagulation: Which? Where? When?  

PubMed Central

Tissue factor (TF) is an integral membrane protein, normally separated from the blood by the vascular endothelium, which plays a key role in the initiation of blood coagulation. With a perforating vascular injury, TF becomes exposed to blood and binds plasma factor VIIa. The resulting complex initiates a series of enzymatic reactions leading to clot formation and vascular sealing. In some pathologic states, circulating blood cells express TF as a result of exposure to an inflammatory stimulus leading to intravascular clotting, vessel occlusion and thrombotic pathology. Numerous controversies have arisen related to the influence of structural features of TF, its presentation and its function. There are contradictory reports about the synthesis and presentation of TF on blood cells and the presence (or absence) of functionally active TF circulating in normal blood either on microparticles or as a soluble protein. In this review we discuss TF structure-function relationships and the role of TF during various phases of the blood coagulation process. We also highlight controversies concerning the expression/presence of TF on various cells and in blood in normal and pathologic states. PMID:19592470

Butenas, Saulius; Orfeo, Thomas; Mann, Kenneth G.

2009-01-01

245

Coagulation parameters in inflammatory bowel disease  

PubMed Central

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

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

2014-01-01

246

The Liquid Argon Purity Demonstrator  

E-print Network

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

Adamowski, M; 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

2014-01-01

247

Study of fluid mechanical helium argon ion laser  

NASA Technical Reports Server (NTRS)

An approach to an argon ion laser based on gasdynamic techniques is presented. Improvement in efficiency and power output are achieved by eliminating high heat rejection problems and plasma confinement of the seal-off conventional lasers. The process of producing population inversion between the same energy levels, as in the conventional argon ion laser, has been divided into two phases by separating each other from the processes of ionization and subsequent excitation. Line drawings and graphs are included to amplify the theoretical presentation.

1972-01-01

248

Platelet aggregation and coagulation factors in orthopedic surgery.  

PubMed

Hemostasis is a major concern during the perioperative period. Changes in platelet aggregation and coagulation factors may contribute to the delicate balance between thrombosis and bleeding. We sought to better understand perioperative hemostasis by investigating the changes in platelet aggregation and coagulation factors during the perioperative period. We performed a prospective cohort analysis of 70 subjects undergoing non-emergent orthopedic surgery of the knee (n = 28), hip (n = 35), or spine (n = 7) between August 2011 and November 2011. Plasma was collected preoperatively (T1), 1-h intraoperatively (T2), 1-h (T3), 24-h (T4) and 48-h (T5) postoperatively. Platelet function testing was performed using whole blood impedance aggregometry. Coagulation assays were performed for factor VII, factor VIII, von Willebrand Factor (vWF), and fibrinogen. Of the 70 patients, mean age was 64.1 ± 9.8 years, 61 % were female, and 74 % were Caucasian. Platelet activity decreased until 1 h postoperatively and then significantly increased above baseline at 24- and 48-h postoperatively. Compared to baseline, coagulation factors decreased intraoperatively. Factor VII activity continued to decrease, while FVIII, vWF, and fibrinogen all increased above baseline postoperatively. The results of our study indicate significant changes in platelet activity and coagulation factors during the perioperative period. Both platelet activity and markers of coagulation decrease during the intraoperative period and then some increase postoperatively. These changes may contribute to the hypercoagulabity and/or bleeding risk that occurs in the perioperative period. Future prospective studies aimed at correlating hemostatic changes with perioperative outcomes are warranted. PMID:24874897

Oberweis, Brandon S; Cuff, Germaine; Rosenberg, Andrew; Pardo, Luis; Nardi, Michael A; Guo, Yu; Dweck, Ezra; Marshall, Mitchell; Steiger, David; Stuchin, Steven; Berger, Jeffrey S

2014-11-01

249

Quantification of coagulation factors and inhibitors. Still a special task.  

PubMed

This is a very short review on quantitative coagulation factor assays for the beginner. For systematic training several excellent textbooks in German language are available. Quantitative functional assays of coagulation factors and of physiological inhibitor proteins are based on the principle of parallel-line or slope ratio bioassays. With the modern analyzers the test procedure follows the example of clinical chemistry: a single test plasma dilution read from an actual calibration curve, regular internal and external quality control. If there are unexpected results or a suspicion of haemophilia we recommend to repeat the assay with three different pre-dilutions of the test plasma. The resulting potency estimates should not deviate by more than 10-15% from their average. Otherwise the assay is invalid and requires further investigation (e.g. search for inhibitors). Special problems may complicate diagnostic activities. As an example discrepancies between factor VIII one-stage clotting and chromogenic assays are discussed. PMID:16444320

Marbet, G A

2006-01-01

250

Fractal Coagulation Bruce E. Logan  

E-print Network

Fractal Coagulation Kinetics Bruce E. Logan Department of Civil & Environmental Engineering paradigm shift is needed to explain the formation of marine snow? #12;Birth of Fractal Geometry ·In 1982, Benoit Mandelbrot publishes "Fractal Geometry" and fractal mathematics is born. ·Fractal scaling

251

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

PubMed Central

Previous studies have shown that stimulation of whole blood or peripheral blood mononuclear cells with bacterial virulence factors results in the sequestration of pro-coagulant microvesicles (MVs). These particles explore their clotting activity via the extrinsic and intrinsic pathway of coagulation; however, their pathophysiological role in infectious diseases remains enigmatic. Here we describe that the interaction of pro-coagulant MVs with bacteria of the species Streptococcus pyogenes is part of the early immune response to the invading pathogen. As shown by negative staining electron microscopy and clotting assays, pro-coagulant MVs bind in the presence of plasma to the bacterial surface. Fibrinogen was identified as a linker that, through binding to the M1 protein of S. pyogenes, allows the opsonization of the bacteria by MVs. Surface plasmon resonance analysis revealed a strong interaction between pro-coagulant MVs and fibrinogen with a KD value in the nanomolar range. When performing a mass-spectrometry-based strategy to determine the protein quantity, a significant up-regulation of the fibrinogen-binding integrins CD18 and CD11b on pro-coagulant MVs was recorded. Finally we show that plasma clots induced by pro-coagulant MVs are able to prevent bacterial dissemination and possess antimicrobial activity. These findings were confirmed by in vivo experiments, as local treatment with pro-coagulant MVs dampens bacterial spreading to other organs and improved survival in an invasive streptococcal mouse model of infection. Taken together, our data implicate that pro-coagulant MVs play an important role in the early response of the innate immune system in infectious diseases. PMID:23935504

Oehmcke, Sonja; Westman, Johannes; Malmström, Johan; Mörgelin, Matthias; Olin, Anders I.; Kreikemeyer, Bernd; Herwald, Heiko

2013-01-01

252

[Activation of coagulation and fibrinolysis in patients with abdominal true aortic aneurysm associated with disseminated intravascular coagulation].  

PubMed

Two cases of abdominal true aortic aneurysm (AAA) associated with disseminated intravascular coagulation (DIC) were reported. Case 1 was an 81-year-old male who was admitted because of hematoma on the left leg and in whom was found by MRI an aortic aneurysm of 14 cm in diameter. Coagulation studies indicated DIC by revealing thrombocytopenia, hypofibrinogenemia and increased level of FDP. DIC was well controlled by surgical repair of the aneurysm after the administration of a small dose of heparin. Case 2 was a 60-year-old male who was admitted because of lumbago and hematoemesis and in whom was found by CT and echography an aortic aneurysm of 5.5 cm in diameter. Coagulation studies indicated DIC by revealing thrombocytopenia and an increased level of FDP. On the 2nd hospital day, he suddenly died due to the rupture of the aortic aneurysm. In most of 9 cases with AAA without DIC, plasma levels of thrombin-antithrombin III complex, plasmin-alpha 2 plasmin inhibitor complex and FDP-D dimer were also elevated. These findings indicate that the coagulation and fibrinolysis systems were generally activated in patients with AAA, and that DIC tends to occur in patients with a giant aortic aneurysm or an impending ruptured aneurysm. PMID:8469833

Akaike, M; Yokoi, K; Wada, M; Sebe, T; Shigekiyo, T; Kawai, H; Saito, S

1993-03-01

253

Axial evolution of radial heat flux profiles transmitted by atmospheric pressure nitrogen and argon arcs  

NASA Astrophysics Data System (ADS)

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.

Meher, K. C.; Tiwari, N.; Ghorui, S.; Sahasrabudhe, S. N.; Das, A. K.

2014-12-01

254

Long-term efficacy of endoscopic coagulation for different types of gastric vascular ectasia  

PubMed Central

AIM: To examine the long-term therapeutic efficacies of endoscopic cauterization for gastric vascular ectasia, according to the type of lesion. METHODS: Thirty-eight patients with hemorrhagic gastric vascular ectasia (VE) were treated by endoscopic cauterization: 13 by heater probe coagulationand 25 by argon plasma coagulation. Depending on the number of lesions, 14 and 24 patients were classified into localized VE (? 10; LVE) and extensive VE (> 10; EVE), respectively. The patients were followed-up by repeated endoscopic examinations after the therapy, and the incidences of VE recurrence and re-bleeding from the lesions were evaluated. RESULTS: Although the VE lesions disappeared initially in all the patients after the therapy, the recurrence of VE developed in 25 patients (66%) over a mid-term observation period of 32 mo, and re-bleeding occurred in 15 patients (39%). The recurrence of VE was found in all patients with EVE, with re-bleeding occurring in 14 patients (58%). In contrast, only 1 patient (7%) with LVE showed recurrence of the lesions and complicating hemorrhage. Both the cumulative recurrence-free rates and cumulative re-bleeding-free rates were significantly lower in the EVE group than in the LVE group (P < 0.001 and P < 0.001, respectively). Moreover, the cumulative re-bleeding-free rate in the EVE group was 47.6% at 1 year and 25.4% at 2 years in patients with chronic renal failure, which were significantly lower than the rates in the patients without chronic renal failure (83.3% and 74.1%, respectively) (P < 0.05). CONCLUSION: The recurrence of VE and re-bleeding from the lesions was more frequent in the patients with EVE, especially in those with complicating renal failure. PMID:23687417

Imai, Yukinori; Mizuno, Yoshie; Yoshino, Kiyoko; Watanabe, Kazuhiro; Sugawara, Kayoko; Motoya, Daisuke; Oka, Masashi; Mochida, Satoshi

2013-01-01

255

Correlation of activated clotting times and standard laboratory coagulation tests in paediatric non-cardiac surgery.  

PubMed

The activated clotting time (ACT) was invented as a whole blood test to detect coagulopathy, but nowadays is almost exclusively used to guide heparin anticoagulation. Although the ACT provides a fairly reliable and fast bedside test of the coagulation status, only a few studies have focused on its use to monitor pre- or intraoperative coagulation status as an early marker of impaired haemostasis or increased bleeding tendency. The aim of this study was to compare intraoperative i-STAT(®) ACT values with commonly used thresholds of standard coagulation tests for the diagnosis of coagulopathy during paediatric non-cardiac surgery. We performed a prospective, observational study in a University Children's hospital and included 50 paediatric patients who underwent major elective, non-cardiac, surgery. The i-STAT(®) kaolin ACT test was obtained intraoperatively and compared to the commonly used threshold of standard coagulation tests (PT/INR, aPTT, and plasma fibrinogen level). A total of 181 blood samples were taken from 50 pediatric patients. Moderate correlation was found between ACT and aPTT (r = 0.694; p < 0.001), and all other coagulation tests. The median ACT values remained within the normal range throughout the entire surgical phase, while standard coagulation tests were mostly abnormal during surgery. Intraoperative measurement of ACT did not provide comparable thresholds of normal haemostasis as compared to standard coagulation testing. PMID:23094763

Haas, Thorsten; Spielmann, Nelly; Mauch, Jacqueline; Schmugge, Markus; Weiss, Markus

2013-02-01

256

Phospholipase A2-induced coagulation abnormalities after bee sting.  

PubMed

We will examine the correlation between various bee venom phospholipase A2 (PLA2) concentrations and several parameters of coagulation in human plasma in order to offer a rationale for requesting a particular laboratory coagulation test after bee sting(s). We will also evaluate in vitro the influence of clinically available drugs with a noncompetitive inhibitory effect on PLA2 on the anticoagulant effect of bee venom PLA2. Prothrombin index (PTi), partial thromboplastin time (PTT), antithrombin III (AT III), soluble fibrin monomers (SFM), the activity of coagulation factors I, II, V, and VIII, and thrombelastography (TEG) parameters (split point [Sp], reaction time [R], kinetic time [K], coagulation time [R + K], maximal amplitude [MA], and the growth angle [alpha]) were determined before and after addition of 1.4, 2.7, and 4.1 units (1, 2, and 3 microg protein respectively) of bee venom PLA2. Linear regression was used to determine the significance of the relationship between these coagulation parameters and bee venom PLA2 concentrations used. To study the influence of ketamine, lidocaine, magnesium, furosemide, and cromolyn on the anticoagulant effect of bee venom PLA2, PTi and factor II- and V-activities were measured before and after addition of 2.7 units of PLA2 and PLA2 plus one of the tested substances. Determinations of F II, PTi, F V, and F VIII showed a negative correlation to bee venom PLA2 concentration (r = -0.88, -0.86, -0.81, and -0.79 respectively). A positive correlation was found for PTT (r = 0.69). FII- activity and PTi correlated better with bee venom PLA2 concentration than other parameters. F I, AT III, and SFM showed no changes. Whereas Sp, R, and K were prolonged by bee venom PLA2 and a was reduced, there was no correlation to the PLA2 concentration. Addition of none of the 5 substances could correct the effects of bee venom PLA2 on the coagulation. In a patient with toxic reaction or a severe anaphylactic reaction after bee sting(s) we suggest determinations of FII and/or PTi. This will allow a quick and economical assessment of coagulation abnormalities after bee sting(s). Noncompetitive PLA2-inhibitors (ketamine, lidocaine, magnesium, furosemide, and cromolyn) are unable to correct in vitro the anticoagulant effect of bee venom PLA2. They cannot be recommended at this stage for this purpose. Further investigations with competitive PLA2-inhibitors are warranted. PMID:10674526

Petroianu, G; Liu, J; Helfrich, U; Maleck, W; Rüfer, R

2000-01-01

257

Electron densities and energies of a guided argon streamer in argon and air environments  

NASA Astrophysics Data System (ADS)

In this study we report the temporally and spatially resolved electron densities and mean energies of a guided argon streamer in ambient argon and air obtained by Thomson laser scattering. The plasma is driven by a positive monopolar 3.5 kV pulse, with a pulse width of 500 ns and a frequency of 5 kHz which is synchronized with the high repetition rate laser system. This configuration enables us to use the spatial and temporal stability of the guided streamer to accumulate a multitude of laser/plasma shots by a triple grating spectrometer equipped with an ICCD camera and to determine the electron parameters. We found a strong initial ne-overshoot with a maximum of 7 × 1019 m-3 and a mean electron energy of 4.5 eV. This maximum is followed by a fast decay toward the streamer channel. Moreover, a 2D distribution of the electron density is obtained which exhibits a peculiar mushroom-like shape of the streamer head with a diameter significantly larger than that of the emission profile. A correlation of the width of the streamer head with the expected pre-ionization channel is found.

Hübner, S.; Hofmann, S.; van Veldhuizen, E. M.; Bruggeman, P. J.

2013-12-01

258

Insights into platelet-based control of coagulation.  

PubMed

The coagulation process is activated by tight control mechanisms, in which platelets play prominent and unique roles. In thrombosis and hemostasis, activated platelets regulate the coagulation system in various ways: by exposing a phosphatidylserine surface for thrombin formation, by supporting fibrin formation, and by regulating the retraction of a fibrin clot. In this review we discuss the involvement of platelet receptors, other membrane proteins, downstream signaling proteins, cytoskeleton-linked proteins and plasma proteins in these procoagulant functions. Studies with both genetically modified mice and pharmacological inhibitors indicate that, for collagen-adhered platelets, in part common signaling pathways lead to phosphatidylserine exposure, generation of thrombin and fibrin, and retraction of the fibrin clot. However, prolonged Ca(2+) elevation leads to thrombin generation, whereas integrin-dependent signaling stimulates fibrin clot retraction. Contact-dependent signaling pathways, triggered by homotypic platelet-platelet interactions, act in particular via the integrin route. PMID:24862135

de Witt, Susanne M; Verdoold, Remco; Cosemans, Judith M E M; Heemskerk, Johan W M

2014-05-01

259

Bleeding and coagulation in the PACU.  

PubMed

Understanding normal coagulation processes will allow the critical care nurse to also understand disorders of coagulation. Understanding diagnostic tests used to assess coagulation will also allow the critical care nurse to evaluate disorders of coagulation and to identify patients at risk for bleeding disorders. Both should encourage the critical care nurse to institute appropriate measures designed to minimize and detect further bleeding. Nursing interventions will include maintenance of aseptic technique; minimizing tissue trauma (avoid venipunctures, use of a soft toothbrush); guaiacing stools; monitoring oxygenation and level of consciousness; and monitoring laboratory tests, including hemoglobin and hematocrit, along with laboratory tests of coagulation. Prompt detection and intervention will help minimize the morbidity and mortality associated with bleeding and alterations in coagulation. PMID:2043321

Litwack, K

1991-03-01

260

Coagulation disorders after traumatic brain injury  

Microsoft Academic Search

Summary  \\u000a Background. Over the past decade new insights in our understanding of coagulation have identified the prominent role of tissue factor.\\u000a The brain is rich in tissue factor, and injury to the brain may initiate disturbances in local and systemic coagulation. We\\u000a aimed to review the current knowledge on the pathophysiology, incidence, nature, prognosis and treatment of coagulation disorders\\u000a following

B. S. Harhangi; E. J. O. Kompanje; F. W. G. Leebeek; A. I. R. Maas

2008-01-01

261

Determination of the Optimal Conditions for the Coagulation-based Water Purification Using Modified Coagulation Test  

Microsoft Academic Search

The aggregation stability of sulfate lignin in aqueous AlCl3 and Al2(SO4)3 solutions within wide ranges of pH values and coagulant concentrations was studied by spectrophotometry. From the obtained experimental data, a new approach was proposed to determine the optimal conditions (pH, coagulant dose) for the coagulation-based water purification, a modified coagulation test allowing for the elimination of the drawbacks inherent

A. V. Lorentsson; Yu. M. Chernoberezhskii; A. B. Dyagileva

2002-01-01

262

Coagulation activation in an experimental pneumonia model in malnourished mice.  

PubMed

Malnutrition induces a decrease in immunity that affects the ability of the organism to deal with an infectious challenge. The clotting system is considered a branch of immunity and its activation is important in the pathogenesis of an infectious disease. This work was conducted to determine coagulation modifications in malnourished hosts before and during infection. Weaned mice were malnourished via a protein-free diet. Well-nourished control mice (WNC) consumed a balanced conventional diet. Malnourished mice (MN) and WNC were challenged intranasally with Streptococcus pneumoniae. Blood, bronchoalveolar lavages (BAL), and lung samples were taken at different times post infection. The results were that MN showed altered hemostatic tests and fibrin(ogen) deposits in the lung. Thus, an increase in thrombin-antithrombin complexes (TATc) in plasma and BAL was observed. In the MN group, infection induced a rise in TATc in plasma and BAL and increased plasma fibrinogen and fibrin(ogen) deposits in the lung. A decrease in activated protein C and antithrombin in BAL and an early decrease followed by an increase in plasma Factor VIII were also observed. Thus, malnourishment induced a procoagulant state increased by infection. This is the first work that presents results of an exhaustive study of coagulation in malnourished hosts before and during an infection. PMID:21186376

Zelaya, Hortensia; Haro, Cecilia; Laiño, Jonathan; Alvarez, Susana; Agüero, Graciela

2011-01-01

263

Characterization of recombinant human coagulation factor XFriuli.  

PubMed

Naturally occurring plasma factor XFriuli (pFXFr) is marginally activated by both the extrinsic and intrinsic coagulation pathways and has impaired catalytic potential. These studies were initiated to obtain confirmation that this molecule is multi-functionally defective due to the substitution of Ser for Pro at position 343 in the catalytic domain. By the Nelson-Long site-directed mutagenesis procedure a construct of cDNA in pRc/CMV was derived for recombinant factor XFriuli (rFXFr) produced in human embryonic (293) kidney cells. The rFXFr was purified and shown to have a molecular size identical to that of normal plasma factor X (pFX) by gel electrophoretic, and amino-terminal sequencing revealed normal processing cleavages. Using recombinant normal plasma factor X (rFXN) as a reference, the post-translational gamma-carboxy-glutamic acid (Gla) and beta-hydroxy aspartic acid (beta-OH-Asp) content of rFXFr was over 85% and close to 100%, respectively, of expected levels. The specific activities of rFXFr in activation and catalytic assays were the same as those of pFXFr. Molecular modeling suggested the involvement of a new H-bond between the side-chains of Ser-343 and Thr-318 as they occur in anti-parallel beta-pleated sheets near the substrate-binding pocket of pFXFr. These results support the conclusion that the observed mutation in pFXFr is responsible for its dysfunctional activation and catalytic potentials, and that it accounts for the moderate bleeding tendency in the homozygous individuals who possess this variant procoagulant. PMID:8815583

Kim, D J; Girolami, A; James, H L

1996-02-01

264

Hematopoietic and nonhematopoietic cell tissue factor activates the coagulation cascade in endotoxemic mice  

PubMed Central

Tissue factor (TF) is the primary activator of the coagulation cascade. During endotoxemia, TF expression leads to disseminated intravascular coagulation. However, the relative contribution of TF expression by different cell types to the activation of coagulation has not been defined. In this study, we investigated the effect of either a selective inhibition of TF expression or cell type-specific deletion of the TF gene (F3) on activation of coagulation in a mouse model of endotoxemia. We found that inhibition of TF on either hematopoietic or nonhematopoietic cells reduced plasma thrombin-antithrombin (TAT) levels 8 hours after administration of bacterial lipopolysaccharide (LPS). In addition, plasma TAT levels were significantly reduced in endotoxemic mice lacking the TF gene in either myeloid cells (TFflox/flox,LysMCre mice) or in both endothelial cells (ECs) and hematopoietic cells (TFflox/flox,Tie-2Cre mice). However, deletion of the TF gene in ECs alone had no effect on LPS-induced plasma TAT levels. Similar results were observed in mice lacking TF in vascular smooth muscle cells. Finally, we found that mouse platelets do not express TF pre-mRNA or mRNA. Our data demonstrate that in a mouse model of endotoxemia activation of the coagulation cascade is initiated by TF expressed by myeloid cells and an unidentified nonhematopoietic cell type(s). PMID:20410508

Pawlinski, Rafal; Wang, Jian-Guo; Owens, A. Phillip; Williams, Julie; Antoniak, Silvio; Tencati, Michael; Luther, Thomas; Rowley, Jesse W.; Low, Elizabeth N.; Weyrich, Andrew S.

2010-01-01

265

Hirudin as a molecular probe for thrombin in vitro and during systemic coagulation in the pig.  

PubMed Central

The amount of thrombin active in vivo in the intravascular space (blood and endothelial surface), both basally and in experimental intravascular coagulation, is measured by way of the accessibility of thrombin to intravascular hirudin. Blood samples from pigs given intravenous 125I-labeled hirudin contain 125I-labeled hirudin-thrombin complex in concentrations indicative of a basal thrombin concentration in vivo of 0.5 nmol/liter. Intravenous infusion of Salmonella endotoxin elicits an increase in the circulating concentration of hirudin-thrombin complex that begins within 15 min and is 20-30 times basal after 4 hr. Induction of mild intravascular coagulation is evidenced by a modest reduction in plasma fibrinogen concentrations. It is concluded that there is a basal pool of hirudin-accessible thrombin in the intravascular space that, were it free in the plasma phase, would be sufficient in principle to sustain intravascular coagulation. Images Fig. 5 PMID:8446595

Zoldhelyi, P; Chesebro, J H; Owen, W G

1993-01-01

266

Living donor liver transplantation from an asymptomatic donor with mild coagulation factor IX deficiency: Report of a case.  

PubMed

The use of donors with coagulation FIX deficiency is controversial, and there are no current protocols for peri-transplant management. We herein describe the first reported case of a pediatric LDLT from an asymptomatic donor with mild coagulation FIX deficiency. A 32-yr-old female was evaluated as a donor for her 12-month-old daughter with biliary atresia. The donor's pretransplant coagulation tests revealed asymptomatic mild coagulation FIX deficiency (FIX activity 60.8%). Freeze-dried human blood coagulation FIX concentrate was administered before the dissection of the liver and 12 h afterwards by bolus infusion (40 U/kg) and was continued on POD 1. The bleeding volume at LDLT was 590 mL. On POD 1, 3, 5, and 13, the coagulation FIX activity of the donor was 121.3%, 130.6%, 114.6%, and 50.2%, respectively. The donor's post-transplant course was uneventful, and the recipient is currently doing well at 18 months after LDLT. The FIX activity of the donor and recipient at nine months after LDLT was 39.2% and 58.0%, respectively. LDLT from donors with mild coagulation FIX deficiency could be performed effectively and safely using peri-transplant short-term coagulation FIX replacement and long-term monitoring of the plasma FIX level in the donor. PMID:25213132

Sanada, Yukihiro; Sasanuma, Hideki; Sakuma, Yasunaru; Morishima, Kazue; Kasahara, Naoya; Kaneda, Yuji; Miki, Atsushi; Fujiwara, Takehito; Shimizu, Atsushi; Hyodo, Masanobu; Hirata, Yuta; Yamada, Naoya; Okada, Noriki; Ihara, Yoshiyuki; Urahashi, Taizen; Madoiwa, Seiji; Mimuro, Jun; Mizuta, Koichi; Yasuda, Yoshikazu

2014-12-01

267

Textile wastewater purification through natural coagulants  

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

268

Isolation and study of an acquired inhibitor of human coagulation factor V.  

PubMed Central

A coagulation Factor V inhibitor developed in a man 75 yr of age in association with an anaplastic malignancy and drug treatment (including the aminoglycoside antibiotic, gentamicin). The patient did not bleed abnormally, despite both surgical challenge and plasma Factor V activity of less than 1%. The inhibited plasma had grossly prolonged prothrombin and activated partial thromboplastin times, but a normal thrombin time. Mixing studies indicated progressive coagulation inhibition with normal plasma, but not with Factor V-deficient plasma, and reversal of coagulation inhibition by the addition of bovine Factor V to the patient's plasma. 1 ml of patient plasma inhibited the Factor V activity of 90 ml of normal human plasma. The inhibitor was isolated by sequential affinity chromatography on protein A-Sepharose and Factor V-Sepharose. The IgG isolate markedly inhibits the activity of prothrombinase assembled from purified Factors Xa and Va, calcium ion, and phospholipid vesicles, and partially inhibits prothrombinase assembled from purified Factor Xa, calcium ion, and normal platelets. The Factor V of platelets, however, appears relatively inaccessible to the antibody, inasmuch as platelets isolated from whole blood supplemented for 8 h with the antibody functioned normally with respect to platelet Factor V-mediated prothrombinase function. The absence of obvious hemorrhagic difficulties in the patient, the total inhibition of plasma Factor V by the inhibitor, and the apparent inaccessibility of platelet Factor V to the inhibitor specifically implicate platelet Factor V in the maintenance of hemostasis. Images PMID:3944265

Nesheim, M E; Nichols, W L; Cole, T L; Houston, J G; Schenk, R B; Mann, K G; Bowie, E J

1986-01-01

269

Microstructures and Argon age dating  

NASA Astrophysics Data System (ADS)

Microstructures can be dated using 40Ar/39Ar geochronology, but certain conditions apply. In particular the nature of the physical processes that took place during development of need be identified, and the pattern of gas release (and/or retention) during their evolution in nature, and subsequently in the mass spectrometer, during the measurement process. Most researchers cite temperature as the sole variable of importance. There is a belief that there is a single "closure temperature" or a "closure interval" above which the mineral is incapable of retaining radiogenic argon. This is a false conception. Closure is practically relevant only in circumstances that see a rock cooled relatively rapidly from temperatures that were high enough to prevent significant accumulation of radiogenic argon, to temperatures below which there is insignificant loss of radiogenic argon through the remainder of the geological history. These conditions accurately apply only to a limited subset - for example to rocks that cool rapidly from a melt and thereafter remain at or close to the Earth's surface, without subsequent ingress of fluids that would cause alteration and modification of microstructure. Some minerals in metamorphic rocks might display such "cooling ages" but in principle these data are difficult to interpret since they depend on the rate of cooling, the pressures that applied, and the subsequent geological history. Whereas the science of "cooling ages" is relatively well understood, the science of the Argon Partial Retention Zone is in its infancy. In the Argon PRZ it is evident that ages should (and do) show a strong correlation with microstructure. The difficulty is that, since diffusion of Argon is simultaneously multi-path and multi-scale, it is difficult to directly interrogate the distinct reservoirs that store gas populations and thus the age information that can be recorded as to the multiple events during the history of an individual microstructure. Laser methods invariably record mixing ages, since the spot sizes are large. Carefully designed furnace step-heating experiments on the other hand seem well capable of sequentially extracting ages from different microstructural reservoirs, and this can be tested by comparing samples with different proportions of these microstructures. Here we examine the role of microstructure in Argon ‘age dating' by comparing and contrasting observed measurements with theoretical predictions developed on the basis of modelling and simulation of the effects of multi-path and multi-scale diffusion. We analyse these results in the context of microstructures observed in white micas and K-feldspar, at both the scale of the optical microscope as well as utilising electron microscopy. Examples from three different tectonic settings will be provided to illustrate the effect of the different variables that apply: a) the extensional South Cyclades Shear Zone, Greece; b) granitoids exhumed from ultra-high-pressures in the Dora Maira, Italy; and c) leucogranites shed from the Ladakh Batholith into the Indus Formation, NW India.

Forster, Marnie; Fitz Gerald, John; Lister, Gordon

2010-05-01

270

International biological standards for coagulation factors and inhibitors.  

PubMed

The use of international biological standards during the last 30 years has proved extremely successful in promoting global harmonization of estimates between laboratories and methods. Experience has led to the identification of physical criteria essential for standards to be suitable for long-term use. High precision of liquid filling coupled with low residual moisture and oxygen and the use of sealed glass ampoules have been found consistent with homogeneous and stable International Standards (ISs). Most plasma coagulation factors and inhibitors are calibrated in International Units (IU), which are defined as the amount of analyte in 1 mL of normal pooled plasma. Adoption of the IU has provided clarity in the definition of normal and abnormal states and has facilitated dose calculation for replacement therapy. The assay of like-versus-like materials (e.g., concentrate versus concentrate) has been found to improve interlaboratory agreement and there are now both plasma and concentrate ISs available for many coagulation factors and inhibitors. Studies into the assay of recombinant factor VIII have indicated that additional measures, such as modifications to assay methodology, are necessary to reduce interlaboratory variability. This experience may prove valuable in the future, when we have to deal increasingly with the challenges to standardization associated with the products of bioengineering. PMID:17427063

Hubbard, Anthony R

2007-04-01

271

Prevalence and significance of coagulation abnormalities in community-acquired pneumonia.  

PubMed

Coagulation abnormalities are common in severe pneumonia and sepsis, yet little is known about the presence of coagulopathy or its significance in patients with lesser illness severity. We examined coagulation abnormalities in 939 subjects hospitalized with community-acquired pneumonia (CAP) in 28 US hospitals, hypothesizing that abnormalities would increase with illness severity and poor outcomes. We measured plasma coagulation markers (D-dimer, plasminogen activator inhibitor [PAI], antithrombin, factor IX, and thrombin-antithrombin complex [TAT]) at the time of patient presentation to the emergency department and daily during the first wk of hospitalization. Day-1 clinical laboratory test results for international normalized ratio, activated partial thromboplastin time, and platelet count were recorded from the medical record. In our cohort, 32.5% of patients developed severe sepsis and 11.1% died by d 90. Day-1 coagulation abnormalities were common, especially for D-dimer (80.6%) and TAT (36.0%), and increased with illness severity and poor outcomes. However, abnormalities also occurred in those patients who never developed organ dysfunction and differences between groups were modest. The proportion of patients with abnormalities changed over time, yet the magnitude of change was small and not always in the direction of normality. Many patients remaining in the hospital continued to manifest coagulation abnormalities on d 7, especially for D-dimer (86.5%) and TAT (36.9%). In conclusion, coagulation abnormalities were common and persistent in CAP patients, even among the least ill. These findings underscore the complexity of the coagulation response to infection and may offer insights into coagulation-based therapeutics in clinical sepsis trials. PMID:19753144

Milbrandt, Eric B; Reade, Michael C; Lee, MinJae; Shook, Stephanie L; Angus, Derek C; Kong, Lan; Carter, Melinda; Yealy, Donald M; Kellum, John A

2009-01-01

272

Imaging coagulation reactions in vivo  

PubMed Central

Significant gaps remain in the understanding of how blood cells and the vasculature differentially support coagulation enzyme complex function leading to regulated thrombus formation in vivo. While studies employing knock-out or transgenic mice have proved useful many of these scientific gaps partly result from the lack of molecular approaches and analytic tools with appropriate sensitivity for incisive conclusions. Over the past decade, studies employing state of the art videomicroscopy to image hemostasis in vivo following laser injury to the mouse cremaster arteriole have begun to bridge these gaps and provide remarkable insight into the early events of the hemostatic process. Many of these new insights have started to question some of the long-standing concepts that were driven by in vitro approaches. This review provides an overview of this technology, describes insights that have been made using it, and discuses limitations and future directions. PMID:22405051

Ivanciu, Lacramioara; Krishnaswamy, Sriram; Camire, Rodney M.

2012-01-01

273

Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon/nitrogen  

SciTech Connect

In this letter, atmospheric-pressure glow discharges in {gamma} mode with argon/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the {alpha}-{gamma} coexisting mode or {gamma} mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen, can be employed to generate the stable {gamma} mode radio-frequency, atmospheric-pressure glow discharges and the discharge voltage rises with increasing the fraction of nitrogen in the argon-nitrogen mixture for a constant total gas flow rate.

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

2006-10-16

274

Boltzmann expansion in a radiofrequency conical helicon thruster operating in xenon and argon  

NASA Astrophysics Data System (ADS)

A low pressure (˜0.5 mTorr in xenon and ˜1 mTorr in argon) Boltzmann expansion is experimentally observed on axis within a magnetized (60 to 180 G) radiofrequency (13.56 MHz) conical helicon thruster for input powers up to 900 W using plasma parameters measured with a Langmuir probe. The axial forces, respectively, resulting from the electron and magnetic field pressures are directly measured using a thrust balance for constant maximum plasma pressure and show a higher fuel efficiency for argon compared to xenon.

Charles, C.; Boswell, R.; Takahashi, K.

2013-06-01

275

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

E-print Network

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

276

Nitrogen and argon doped zinc oxide  

NASA Astrophysics Data System (ADS)

In this work argon and nitrogen were implanted into ZnO single crystals in order to compare the influence of these non-magnetic elements in the magnetic and electrical behaviour of zinc oxide. The results indicate that both nitrogen and argon implantations induce magnetic defects in ZnO, although these do not remain stable upon annealing. The comparison between the electrical behaviour of argon and nitrogen implanted crystals indicates that mobile charge carriers exist in the argon implanted sample after annealing, but were not detected in the nitrogen implanted sample.

Silva, C.; Costa, A. R. G.; Cruz, M. M.; da Silva, R. C.; Borges, R. P.; Alves, L. C.; Godinho, M.

2010-09-01

277

Composting Plant Leachate Treatment by Coagulation-Flocculation Process  

Microsoft Academic Search

4 Abstract: This experimental study was conducted to investigate the effect of treatment of composting plant leachate by a coagulation-flocculation process. The effects of different dosages of coagulant and different pH values on the coagulation processes were compared. Ferric chloride and aluminium sulphate (alum) were tested as conventional coagulants. The experimental results show that a 18% removal of COD and

Afshin Maleki; Mohammad Ali Zazouli; Hassan Izanloo; Reza Rezaee

278

Oxidation and coagulation of humic substances by potassium ferrate  

Microsoft Academic Search

Ferrate is believed to have a dual role in water treatment, both as oxidant and coagulant. Few studies have considered the coagulation effect in detail, mainly because of the difficulty of separating the oxidation and coagulation effects. This paper summarises some preliminary results from laboratory-based experiments that are investigating the coagulation reaction dynamically via a PDA instrument, between ferrate and

Nigel Graham; T. T. Khoi; JiaQian Jiang

2010-01-01

279

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...

280

21 CFR 864.5400 - Coagulation instrument.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

281

21 CFR 864.5400 - Coagulation instrument.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

282

21 CFR 864.5400 - Coagulation instrument.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

283

21 CFR 864.5400 - Coagulation instrument.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

284

21 CFR 864.5400 - Coagulation instrument.  

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

2014-04-01

285

Pilot scale comparison of enhanced coagulation with magnetic resin plus coagulation systems.  

PubMed

Previous work has shown that magnetic ion-exchange treatment before coagulation gives high natural organic matter (NOM) removal and reduced levels of disinfection byproduct when compared to conventional enhanced coagulation. The impact of the resin process on the downstream floc formation process after coagulation and the subsequent effect on clarification has not previously been shown. Water containing high concentrations of NOM were treated at pilot scale using (1) conventional enhanced coagulation and compared with (2) treatment using magnetic resin followed by coagulation at reduced doses of 50-70%. Bench scale testing was also carried out to determine floc properties for systems with and without resin pretreatment It was demonstrated that pretreatment using magnetic resin was able to significantly reduce the turbidity load onto filters as a result of the formation of a large and more robust floc. Resin pretreatment also improved NOM removal and reduced disinfection byproduct formation when compared with conventional coagulation. The turbidity load on to the filters following resin pretreatment was 1.5 +/- 0.7 NTU, whereas this value was 2.9 +/- 0.3 NTU for conventional coagulation. Flocs produced with resin pretreatment were larger than those produced by conventional coagulation, with a median floc size of 1000 microm compared to 600 microm. The improvement in floc properties following magnetic resin pretreatment was proposed to be due to the removal of NOM thatwas characteristic of carboxylic acids before the coagulation stage. PMID:18351105

Jarvis, Peter; Mergen, Max; Banks, Jenny; McIntosh, Brian; Parsons, Simon A; Jefferson, Bruce

2008-02-15

286

Effects of Al-coagulant sludge characteristics on the efficiency of coagulants recovery by acidification.  

PubMed

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

Chen, Yi-Jui; Wang, Wen-May; Wei, Ming-Jun; Chen, Jiann-Long; He, Ju-Liang; Chiang, Kung-Yuh; Wu, Chih-Chao

2012-12-01

287

Textile wastewater purification through natural coagulants  

Microsoft Academic Search

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\\u000a Fast Black WAN. This coagulant is lab-synthesized according to the etherification of tannins with glycidyltrimethylammonium\\u000a chloride and formaldehyde and its performance in dye removal in terms of efficiency was high. Reasonably

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

2011-01-01

288

Preparation and coagulation efficiency of polyaluminium ferric silicate chloride composite coagulant from wastewater of high-purity graphite production  

Microsoft Academic Search

The aim of the present work was to produce a polyaluminium ferric silicate chloride (PAFSiC) coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride (PAC). The PAFSiC coagulant

Xiaoxia Niu; Xili Li; Jihong Zhao; Yigang Ren; Yanqin Yang

2011-01-01

289

Coagulation algorithms with size binning  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

290

[Incidental finding of pathological coagulation parameters].  

PubMed

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

Luxembourg, B; Lindhoff-Last, E

2014-10-01

291

Dust Coagulation in Protoplanetary Accretion Disks  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

292

Model of a stationary microwave argon discharge at atmospheric pressure  

SciTech Connect

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.

Zhelyazkov, I. [Faculty of Physics, Sofia University, BG-1164 Sofia (Bulgaria); Pencheva, M.; Benova, E. [Department for Language Teaching and International Students, Sofia University, BG-1111 Sofia (Bulgaria)

2008-03-19

293

Supersonic induction plasma jet modeling  

Microsoft Academic Search

Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent–divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet,

S. E. Selezneva; M. I. Boulos

2001-01-01

294

Calculation of the shifts of argon spectral lines  

SciTech Connect

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.

Christova, M.; Andreev, N. [Department of Applied Physics, Technical University- Sofia, BG-1000 Sofia (Bulgaria); Christov, L. [Faculty of Chemistry, Sofia University, BG-1164 Sofia (Bulgaria); Dimitrijevic, M. S. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

2008-10-22

295

Ovarian cancer, the coagulation pathway, and inflammation  

PubMed Central

Epithelial ovarian cancer (EOC) represents the most frequent cause of death in the United States from a cancer involving the female genital tract. Contributing to the overall poor outcome in EOC patients, are the metastases to the peritoneum and stroma that are common in this cancer. In one study, cDNA microarray analysis was performed on fresh tissue to profile gene expression in patients with EOC. This study showed a number of genes with significantly altered expression in the pelvic peritoneum and stroma, and in the vicinity of EOC implants. These genes included those encoding coagulation factors and regulatory proteins in the coagulation cascade and genes encoding proteins associated with inflammatory responses. In addition to promoting the formation of blood clots, coagulation factors exhibit many other biologic functions as well as tumorigenic functions, the later including tumor cell proliferation, angiogenesis, invasion, and metastasis. Coagulation pathway proteins involved in tumorigenesis consist of factor II (thrombin), thrombin receptor (protease-activated receptors), factor III (tissue factor), factor VII, factor X and factor I (fibrinogen), and fibrin and factor XIII. In a recent study we conducted, we found that factor XII, factor XI, and several coagulation regulatory proteins, including heparin cofactor-II and epithelial protein C receptor (EPCR), were also upregulated in the peritoneum of EOC. In this review, we summarize evidence in support of a role for these factors in promoting tumor cell progression and the formation of ascites. We also discuss the different roles of coagulation factor pathways in the tumor and peritumoral microenvironments as they relate to angiogenesis, proliferation, invasion, and metastasis. . Since inflammatory responses are another characteristic of the peritoneum in EOC, we also discuss the linkage between the coagulation cascade and the cytokines/chemokines involved in inflammation. Interleukin-8, which is considered an important chemokine associated with tumor progression, appears to be a linkage point for coagulation and inflammation in malignancy. Lastly, we review findings regarding the inflammatory process yielded by certain clinical trials of agents that target members of the coagulation cascade in the treatment of cancer. Current data suggest that disrupting certain elements of the coagulation and inflammation processes in the tumor microenvironment could be a new biologic approach to cancer therapeutics. PMID:15969748

Wang, Xipeng; Wang, Ena; Kavanagh, John J; Freedman, Ralph S

2005-01-01

296

Spectroscopic study of an argon plasmajet out of local thermodynamic equilibrium  

Microsoft Academic Search

The properties of an argon plasmajet seeded with a few percent of hydrogen were studied. At atmospheric pressure, significant deviations from local thermodynamic equilibrium are shown. The plasma parameters (electron density N\\/sub e\\/, temperature T) were determined from the broadening and the absolute intensity of hydrogen lines. The transition probabilities and the broadening parameters (width and shift) of some AI

P. Ranson; J. Chapelle

1974-01-01

297

Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes  

PubMed Central

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

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

2014-01-01

298

Observation of ? mode electron heating in dusty argon radio frequency discharges  

SciTech Connect

The time-resolved emission of argon atoms in a dusty plasma has been measured with phase-resolved optical emission spectroscopy using an intensified charge-coupled device camera. For that purpose, three-dimensional dust clouds have been confined in a capacitively coupled rf argon discharge with the help of thermophoretic levitation. While electrons are exclusively heated by the expanding sheath (? mode) in the dust-free case, electron heating takes place in the entire plasma bulk when the discharge volume is filled with dust particles. Such a behavior is known as ? mode, first observed in electronegative plasmas. Furthermore, particle-in-cell simulations have been carried out, which reproduce the trends of the experimental findings. These simulations support previous numerical models showing that the enhanced atomic emission in the plasma can be attributed to a bulk electric field, which is mainly caused by the reduced electrical conductivity due to electron depletion.

Killer, Carsten; Bandelow, Gunnar; Schneider, Ralf; Melzer, André [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)] [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany); Matyash, Konstantin [Universitätsrechenzentrum, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)] [Universitätsrechenzentrum, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)

2013-08-15

299

Imaging of hydrogen halides photochemistry on argon and ice nanoparticles  

NASA Astrophysics Data System (ADS)

The photodissociation dynamics of HX (X = Cl, Br) molecules deposited on large ArN and (H2O)N, bar{N}? 102-103, clusters is investigated at 193 nm using velocity map imaging of H and Cl photofragments. In addition, time-of-flight mass spectrometry after electron ionization complemented by pickup cross section measurements provide information about the composition and structure of the clusters. The hydrogen halides coagulate efficiently to generate smaller (HX)n clusters on ArN upon multiple pickup conditions. This implies a high mobility of HX molecules on argon. On the other hand, the molecules remain isolated on (H2O)N. The photodissociation on ArN leads to strong H-fragment caging manifested by the fragment intensity peaking sharply at zero kinetic energy. Some of the Cl-fragments from HCl photodissociation on ArN are also caged, while some of the fragments escape the cluster directly without losing their kinetic energy. The images of H-fragments from HX on (H2O)N also exhibit a strong central intensity, however, with a different kinetic energy distribution which originates from different processes: the HX acidic dissociation followed by H3O neutral hydronium radical formation after the UV excitation, and the slow H-fragments stem from subsequent decay of the H3O. The corresponding Cl-cofragment from the photoexcitation of the HCl.(H2O)N is trapped in the ice nanoparticle.

Poterya, V.; Lengyel, J.; Pysanenko, A.; Svr?ková, P.; Fárník, M.

2014-08-01

300

Effect of Crocus sativus L. (saffron) on coagulation and anticoagulation systems in healthy volunteers.  

PubMed

Saffron showed some effects on blood coagulation and platelet aggregation in in vitro and in vivo studies. In a clinical trial with a limited number volunteers, saffron tablets influenced on bleeding time. In this study, the effect of saffron on plasma level of fibrinogen, factor VII (as coagulant agent), C and S protein (as anti-coagulant agent), PT and PTT in a larger sample size was evaluated. The study was a double-blind, placebo-controlled study consisting of 1?week treatment with 200?mg and 400?mg saffron tablets. Sixty healthy volunteers (age range 20-50?years) were selected for the study. The volunteers were divided into three groups of 20 each. Group 1 received placebo; Groups 2 and 3 received 200?mg and 400?mg saffron tablets, respectively, for 7?days (1 tablet per day). Before and after 7?days treatment and also 1?month after that, blood samples were taken. The plasma levels of fibrinogen, factor VII, C and S protein, PT and PTT were evaluated. Statistical analysis showed no difference between groups for any of evaluated factors. This study rejected any effect of saffron with dose of 200 and 400?mg for 1?week on coagulant and anticoagulant system. PMID:23733488

Ayatollahi, Hossein; Javan, Atefeh Ordoei; Khajedaluee, Mohammad; Shahroodian, Masood; Hosseinzadeh, Hossein

2014-04-01

301

Argon gas dilution effect on the properties of amorphous carbon nitride thin films  

Microsoft Academic Search

Optical and structural properties of amorphous carbon nitride (a-C:Nx) thin films deposited on p-type silicon (p-Si) and quartz substrates by microwave (MW) surface-wave plasma (SWP) chemical vapor deposition (CVD) at low temperature (<100 °C) were analyzed in this paper. Argon (Ar: 100 sccm ?300 sccm) was used as carrier gas while acetylene (C2H2: 5 sccm) and nitrogen (N: 5 sccm) were used as plasma source.

Hare Ram Aryal; Sudip Adhikari; Dilip Chandra Ghimire; Hideo Uchida; Masayoshi Umeno

2007-01-01

302

Coagulation and fragmentation dynamics of inertial particles  

E-print Network

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

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

2009-05-22

303

Probe measurements in thermal plasma jets  

Microsoft Academic Search

Measurements of composition, temperature, and velocity in atmospheric argon plasma jets are reported, using enthalpy probes. The plasma jets are generated by a commercial type plasma gun and the measurements are expected to be of particular interest for industrial applications such as plasma spraying. Emphasis has been on the central and downstream regions of the plasma flame. The entrainment of

M. Brossa; E. Pfender

1988-01-01

304

Nonequilibrium effects in supersonic induction plasma  

Microsoft Academic Search

Supersonic plasma jets find applications in plasma chemistry and plasma processing, metallurgy, experimental physics, and space technology. Usually the plasma in these jets deviates from chemical and thermal equilibrium. To optimize the industrial process detailed study of nonequilibrium effects in supersonic flow is required. In the article we apply numerical simulation to study the supersonically accelerated argon plasma flow downstream

S. E. Selezneva; M. I. Boulos

2002-01-01

305

Electron scattering from argon: Data evaluation and consistency  

SciTech Connect

The demand for coherent scattering data for modeling electron transport in matter has increased in recent years. While much effort has been devoted to the improvement of models describing electron transport and scattering, the updating of fundamental data sets on the basis of recent experimental results has often been neglected. The use of a well-validated set of electron cross sections ensures accurate calculations of transport parameters and ionization yields, with typical applications in material analysis, detector response studies, plasma diagnostics, physics of the atmosphere, and radiotherapy. Data consistency can be verified on the basis of various theoretical requirements, and systematic errors can be minimized by cross-checking results obtained from independent experiments. For example, the oscillator strength distribution of an atom can be obtained both from photoabsorption experiments and from zero-angle electron-atom collisions at high energy, on the basis of the Bethe theory. A considerable number of all electron-scattering experiments are concerned with light noble gases, in particular with argon. This gas is a dominant constituent of noble-gas discharge plasmas and plays an important role in rare-gas halide lasers and proportional scintillator counters. This work reviews electron-scattering cross sections and optical data for the argon atom, discusses the progress made in the field of electron scattering and photoabsorption, and focuses on the most appropriate criteria for verifying data consistency.

Gargioni, E.; Grosswendt, B. [Physikalisch-Technische Bundesanstalt, 38116 Braunschweig (Germany)

2008-04-15

306

Nickel atom and ion densities in an inductively coupled plasma with an internal coil  

E-print Network

Nickel atom and ion densities in an inductively coupled plasma with an internal coil Lin Xua Plasma was measured in an inductively coupled argon plasma with an internal Ni coil, as a function of pressure frequency rf high-density inductively coupled plasma ICP is created in an inert gas e.g., argon , usually

Economou, Demetre J.

307

Role of Coagulation in Xenobiotic-Induced Liver Injury  

E-print Network

The liver is a common target for xenobiotic-induced toxicity. Of importance, synthesis of soluble coagulation factors by the liver plays an essential role in hemostasis. Blood coagulation cascade activation is evident in ...

Sullivan, Bradley P.

2012-08-31

308

Computer-assisted interstitial laser coagulation for BPH  

NASA Astrophysics Data System (ADS)

Interstitial laser thermotherapy is a minimally invasive surgical procedure that utilizes laser to coagulate and treat benign prostatic hyperplasia. This study explores the use of a computer-assisted interstitial laser coagulation system to aid surgeons in performing this procedure.

Ho, Gideon; Barrett, Adrian R. W.; Ng, Wan S.; Lim, Liam G.; Cheng, Wai S.

2001-06-01

309

Etching of Bacillus atrophaeus by oxygen atoms, molecules and argon ions  

NASA Astrophysics Data System (ADS)

The etching of spores of Bacillus atrophaeus by oxygen atoms, molecules and argon ions is investigated in a particle beam experiment. Thereby, the conditions occurring in an argon oxygen plasma are mimicked and fundamental inactivation mechanisms are revealed. It is shown that only the combined impact of argon ions and of O atoms or O2 molecules causes significant etching of the spores. This is explained by the process of chemical sputtering, where an ion induced defect at the surface of the spore reacts with either the incident bi-radical O2 or with an incident O atom. This leads to the formation of CO, CO2 and H2O and thus to erosion. This process is compared to the plasma etching of hydrocarbon thin films as an atomistic model system for the spore coat. It is shown that the etch rate in an inductively coupled argon oxygen plasma is only maximal if both, the electron density and thus the ion flux towards the surface and the O atom flux are optimized simultaneously.

Benedikt, J.; Flötgen, C.; Kussel, G.; Raball, V.; von Keudell, A.

2008-10-01

310

Coagulation factor XIII serves as protein disulfide isomerase.  

PubMed

Tissue transglutaminase was reported to act as protein disulfide isomerase (PDI). We studied whether plasma transglutaminase - coagulation factor XIII (FXIII) - has PDI activity as well. PDI activity was measured by determining the ability to renature reduced-denatured RNase (rdRNase). We found that FXIII can renature rdRNase, with efficiency comparable to commercial PDI. This PDI activity was inhibited by bacitracin. Like tissue transglutaminase, FXIII-mediated PDI activity is independent of its transglutaminase activity and is located on the A subunit. Surface-associated PDI has been previously shown to catalyse two distinct functions: transnitrosation with subsequent release of intracellular nitric oxide and disulfide bond rearrangement during platelet integrin ligation. Our results imply that FXIII-PDI activity may have a role in platelet function. PMID:19404536

Lahav, Judith; Karniel, Eli; Bagoly, Zsuzsa; Sheptovitsky, Vera; Dardik, Rima; Inbal, Aida

2009-05-01

311

Monitoring blood coagulation with QCM and SH SAW sensors  

Microsoft Academic Search

Investigations concerning a coagulation sensor based on shear horizontal surface acoustic waves (SH-SAW) are described. As a first step, experimental work was focused on a simpler system: a quartz crystal micro balance (QCM) also called thickness shear mode resonator (TSM). In the literature the suitability of such devices for the characterization of coagulation process is already described. Coagulation tests like

Glen Guhr; Reinhard Kunze; Günter Martin; Hagen Schmidt; M. Weihnachr; Siegmund Gehrisch; Gabriele Siegert

2005-01-01

312

ORIGINAL PAPER Variations in coagulation properties of cheese milk  

E-print Network

ORIGINAL PAPER Variations in coagulation properties of cheese milk from three Danish dairy breeds a study on the variation of coagulation properties in individual cow's milk measured by a novel free of poorly and even non-coagulating (NC) milk in Denmark, and based on that, the paper reports

Boyer, Edmond

313

Original article Rennet coagulation of skim milk and curd drainage  

E-print Network

Original article Rennet coagulation of skim milk and curd drainage: Effect of pH, casein coagulation, gel syneresis and drainage were tested. Coagulation was measured using a formagraph and by viscoelasticimetry, while syneresis was studied using a centrifugation test. Drainage was followed under conditions

Paris-Sud XI, Université de

314

Evaluating Alternative Coagulants to Determine Efficiency and Cost Effectiveness  

Microsoft Academic Search

Ferrous sulfate was studied as an alternative coagulant to ferric chloride. Coagulants were evaluated for iron content, heavy metal contaminants, acidity, chlorine demand, and settleable solids. Jar tests and split-plant trials demonstrated similar performance at comparable costs with either coagulant. An anomaly that was evident throughout the study was that a pound of iron in the form of ferrous sulfate

William R. McKeon; John J. Muldowney

1987-01-01

315

Brownian coagulation at high particle concentrations  

Microsoft Academic Search

The process of Brownian coagulation, whereby particles are brought together by thermal motion and grow by collisions, is one of the most fundamental processes influencing the final properties of particulate matter in a variety of technically important systems. It is of importance in colloids, emulsions, flocculation, air pollution, soot formation, materials manufacture and growth of interstellar dust, to name a

T. M. Trzeciak

2012-01-01

316

Second Discharge Characteristics of Aluminum Wire Electrical Explosion Under Various Argon Pressures  

NASA Astrophysics Data System (ADS)

Electrical wire explosion is a promising method for the preparation of metal nanopowder, but the properties of metal nanopowder are affected by the second discharge process of electrical wire explosion. The second discharge characteristics of aluminum wire electrical explosion under variant argon pressures were studied in a RLC discharge circuit. The results show that the curve of the second discharge voltages versus the pressure presents a U-shape. To clarify the roles of aluminum vapor and argon in the process of the second discharge, a spectrograph and a high speed framing camera were used to study the radiation spectrum and spatial distribution of the electrical explosion plasma. It is observed that argon participates in the second discharge process under low pressure. A discharge channel develops along the surface of the aluminum vapor. Under higher pressure, a second discharge takes place in the aluminum vapor and the discharge channel is inside the aluminum vapor.

Yan, Wenyu; Zhang, Qiaogen; Zhao, Junping; Chen, Gangliang; Liu, Longchen

2014-10-01

317

An Alternative Modality for the Immunodetection of the Molecular Phenotypes of Coagulation Factor XIIIB  

Microsoft Academic Search

A new technical modality for the typing of coagulation factor XIIIB (F13B) is described. The determination of F13B phenotypes was carried out from desyalized plasma samples by means of polyacrylamide gel isoelectric focusing (pH range 6–8) followed by immunofixation-silver stain. This method combines high sensitivity, low expenditure, and a single methodology. A genetic analysis on F13B phenotypes in the Galician

E. D. Cameselle; B. Caeiro; A. Riveiro

1993-01-01

318

Activation of coagulation in bullous pemphigoid and other eosinophil-related inflammatory skin diseases  

PubMed Central

Bullous pemphigoid (BP) is a skin disease caused by autoantibodies to hemidesmosomal proteins BP180 and BP230, with eosinophils participating in blister formation. Tissue factor (TF), the initiator of coagulation, is embodied within the eosinophil granules and exposed upon activation. We evaluated the coagulation activation in patients with BP (63), chronic urticaria (CU; 20), atopic dermatitis (AD; 14), cutaneous drug reactions (CDRs; six), psoriasis (20), dermatitis herpetiformis (DH; four) and primary cutaneous T cell lymphoma (CTCL; five), and in 40 healthy controls. Prothrombin fragment F1+2 and d-dimer (coagulation markers) were measured by enzyme-linked immunosorbent assay (ELISA) in all plasma samples and BP blister fluid. Skin TF expression was evaluated immunohistochemically in the patients and 20 controls. F1+2 and d-dimer levels were higher in BP plasma than in control plasma (P = 0·0001 for both), and dramatically high in blister fluid; both correlated positively with disease severity, esinophil counts and anti-BP180 antibodies (P = 0·006–0·0001). Plasma F1+2 and d-dimer levels were higher in the CU, AD and CDR patients than in controls (P = 0·0001 for all), but normal in the psoriasis, DH and CTCL patients. Skin TF was expressed in the BP (P = 0·0001), CU (P = 0·0001), AD (P = 0·001) and CDR patients (P = 0·01), but not in the psoriasis, DH or CTCL patients. Co-localization confocal microscopy studies confirmed eosinophils as the source of TF in 10 BP patients. The coagulation cascade is activated in BP and other eosinophil-mediated skin disorders, but not in non-eosinophil driven conditions. This hypercoagulability may contribute to inflammation, tissue damage and, possibly, thrombotic risk. PMID:21488867

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

2011-01-01

319

Optimized Coagulation of High Alkalinity, Low Temperature and Particle Water: pH Adjustment and Polyelectrolytes as Coagulant Aids  

Microsoft Academic Search

The Yellow River in winter as source water is characterized as high alkalinity, low temperature and low particle concentrations,\\u000a which have brought many difficulties to water treatment plants. This study fully examines the optimized coagulation process\\u000a of the Yellow River by conventional and pre-polymerized metal coagulants, pH adjustment and polyelectrolytes as the primary\\u000a coagulants or coagulant aids. For all the

Jianfeng Yu; Dongsheng Wang; Mingquan Yan; Changqing Ye; Min Yang; Xiaopeng Ge

2007-01-01

320

Could light meal jeopardize laboratory coagulation tests?  

PubMed Central

Background: Presently the necessity of fasting time for coagulation tests is not standardized. Our hypothesis is that this can harm patient safety. This study is aimed at evaluating whether a light meal (i.e. breakfast) can jeopardize laboratory coagulation tests. Materials and methods: A blood sample was firstly collected from 17 fasting volunteers (12 h). Immediately after blood collection, the volunteers consumed a light meal. Then samples were collected at 1, 2 and 4 h after the meal. Coagulation tests included: activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen (Fbg), antithrombin III (AT), protein C (PC) and protein S (PS). Differences between samples were assessed by Wilcoxon ranked-pairs test. The level of statistical significance was set at P < 0.05. Mean % differences were determined and differences between and baseline and 1, 2 and 4h samples were compared with reference change value (RCV). Results: A significantly higher % activity of AT was observed at 1 h and 4 h after meal vs. baseline specimen [113 (104–117) and 111 (107–120) vs. 109 (102–118), respectively; P = 0.029 and P = 0.016]. APTT at 2 h was found significantly lower than baseline samples [32.0 (29.9–34.8) vs. 34.1 (32.2–35.2), respectively; P = 0.041]. The results of both Fbg and PS tests were not influenced by a light meal. Furthermore, no coagulation tests had significant variation after comparison with RCV. Conclusion: A light meal does not influence the laboratory coagulation tests we assessed, but we suggest that the laboratory quality managers standardize the fasting time for all blood tests at 12 hours, to completely metabolize the lipids intake. PMID:25351352

Lima-Oliveira, Gabriel; Salvagno, Gian Luca; Lippi, Giuseppe; Danese, Elisa; Gelati, Matteo; Montagnana, Martina; Picheth, Geraldo; Guidi, Gian Cesare

2014-01-01

321

Novel sensor combining impedance spectroscopy and surface acoustic waves to detect blood coagulation time and hematocrit value  

Microsoft Academic Search

In this paper a new tool simultaneously to detect viscoelastic and dielectric properties of human fluids is presented. Therefore, one-port SAW resonators (SAW … surface acoustic wave) with fundamental modes of 85, 170 und 340 MHz were developed. Shear horizontal polarized surface acoustic waves (SH-SAW) are used to detect the viscoelastic properties of coagulating blood and blood plasma samples. The

G. Guhr; R. Brunig; H. Schmidt; M. Weihnacht; S. Gehrisch; G. Siegert

2011-01-01

322

New Measurement of ^39Ar in Underground Argon with a Low Background Liquid Argon Detector  

NASA Astrophysics Data System (ADS)

A low background liquid argon detector has been developed for sensitive measurements of the beta radioactive ^39Ar in argon from underground sources. The measurement is motivated by the need to improve on earlier studies that showed no sign of ^39Ar in certain sources of underground argon, but with a limited sensitivity of ˜ 5% relative to ^39Ar in atmospheric argon[1]. We will report preliminary measurements taken with the low background detector that was commissioned and operated at the Kimballton Underground Research Facility (KURF) in Virginia. A combination of passive and active background reduction techniques resulted in a very low background and a null result with sensitivity to ^39Ar less than 1% of atmospheric. The results confirm that underground argon is well suited for direct detection of dark matter WIMPs. [4pt] [1] D. Acosta-Kane et al., Nucl. Instr. Meth. A 587:46 (2008)

Xu, Jingke

2012-03-01

323

Dusty plasmas  

SciTech Connect

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.

Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.

1996-05-01

324

MF/UF performance with and without coagulation  

SciTech Connect

Although size-exclusion membrane processes produce superior water quality relative to conventional surface water treatment, fouling can significantly limit the use of these membrane processes. Coagulation can reduce organic, particulate and biological fouling, and was investigated as a pretreatment process to microfiltration (MF) and ultrafiltration (UF) membrane processes. Varying coagulants, coagulant pH and dose and variation of conventional coagulation pretreatment processes including coagulation-sedimentation-filtration (CSF), coagulation-sedimentation (CS) and in-line coagulation (ILC) for varying dose and pH were investigated. The Hillsborough River, a highly organic productive subtropical surface water in Tampa, Florida and the Maumee River, a moderately productive northern US surface water were used as water sources for this study.

Robert, C.; Taylor, J.S.; Reiss, C.R.

1999-07-01

325

Argon laser and soft tissue interaction  

SciTech Connect

The interaction of the argon laser with the mucous membrane of the upper aerodigestive tract was studied. The advantages of the argon laser are a small spot that can be varied in size and intensity, selective vascular absorption, the capability of being incorporated into a flexible delivery system, and a coincident aiming beam. The acute soft tissue effects are characterized by subepithelial extension, with a variable delayed reaction between the application of the laser and a detectable break in the epithelium. Postoperative edema persisted, with an increase in the lateral spread of the lesion over 3 days and an acute inflammatory reaction extending over 7 days. By 21 days the lesions were reepithelialized and healed, but their width was 30% greater than the original defect. The unpredictable interaction with soft tissue, the postoperative edema, and the quality of wound healing are disadvantages. The argon laser appears to have limited clinical potential as a surgical tool for the air and food passages.

Gillis, T.M.; Strong, M.S.; Shapshay, S.M.; Incze, J.; Simpson, G.

1984-02-01

326

Trapping Cold Ground State Argon Atoms  

NASA Astrophysics Data System (ADS)

We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4 s [3 /2 ]2 state to be (7.3 ±1.1 ) ×10-39 C m2/V . Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3 ±0.8 )×10-10 cm3 s-1 .

Edmunds, P. D.; Barker, P. F.

2014-10-01

327

ICARUS and Status of Liquid Argon Technology  

E-print Network

ICARUS is the largest liquid argon TPC detector ever built (~600 ton LAr mass). It operates underground at the LNGS laboratory in Gran Sasso. It has been smoothly running since summer 2010, collecting data with the CNGS beam and with cosmics. Liquid argon TPCs are really "electronic bubble chamber" providing a completely uniform imaging and calorimetry with unprecedented accuracy on massive volumes. ICARUS is internationally considered as a milestone towards the realization of the next generation of massive detectors (~tens of ktons) for neutrino and rare event physics. Results will be presented on the data collected during 2010 with the detector at LNGS.

Dorota Stefan

2011-10-07

328

Infrared coagulation: A new treatment for hemorrhoids  

Microsoft Academic Search

Many methods, which have effectively reduced the number of patients requiring hospital admisssion, have been described for\\u000a the outpatient treatment of hemorrhoids. However, complications have been reported, and the methods are often associated with\\u000a unpleasant side effects. In 1977 Neigeret al. described a new method that used infrared coagulation, which plroduced minimal side effects.\\u000a \\u000a The authors have conducted a prospective,

Roger J. Leicester; R. John Nicholls; Charles V. Mann

1981-01-01

329

Arsenic removal from drinking water during coagulation  

Microsoft Academic Search

The efficiency of arsenic removal from source waters and artificial freshwaters during coagulation with ferric chloride and alum was examined in bench-scale studies. Arsenic(V) removal by either ferric chloride or alum was relatively insensitive to variations in source water composition below pH 8. At pH 8 and 9, the efficiency of arsenic(V) removal by ferric chloride was decreased in the

Janet G. Hering; Pen-Yuan Chen; Jennifer A. Wilkie; Menachem Elimelech

1997-01-01

330

Patterned retinal coagulation with a scanning laser  

NASA Astrophysics Data System (ADS)

Pan-retinal photocoagulation in patients with diabetic retinopathy typically involves application of more than 1000 laser spots; often resulting in physician fatigue and patient discomfort. We present a semi-automated patterned scanning laser photocoagulator that rapidly applies predetermined patterns of lesions; thus, greatly improving the comfort, efficiency and precision of the treatment. Patterns selected from a graphical user interface are displayed on the retina with an aiming beam, and treatment can be initiated and interrupted by depressing a foot pedal. To deliver a significant number of burns during the eye's fixation time, each pulse should be considerably shorter than conventional 100ms pulse duration. We measured coagulation thresholds and studied clinical and histological outcomes of the application of laser pulses in the range of 1-200ms in pigmented rabbits. Laser power required for producing ophthalmoscopically visible lesions with a laser spot of 132?m decreased from 360 to 37mW with pulse durations increasing from 1 to 100ms. In the range of 10-100ms clinically and histologically equivalent light burns could be produced. The safe therapeutic range of coagulation (ratio of the laser power required to produce a rupture to that for a light burn) decreased with decreasing pulse duration: from 3.8 at 100ms, to 3.0 at 20ms, to 2.5 at 10ms, and to 1.1 at 1ms. Histology demonstrated increased confinement of the thermal damage with shorter pulses, with coagulation zone limited to the photoreceptor layer at pulses shorter than 10ms. Durations of 10-20ms appear to be a good compromise between the speed and safety of retinal coagulation. Rapid application of multiple lesions greatly improves the speed, precision, and reduces pain in retinal photocoagulation.

Palanker, Daniel; Jain, ATul; Paulus, Yannis; Andersen, Dan; Blumenkranz, Mark S.

2007-02-01

331

Electrocoagulation versus chemical coagulation: coagulation/flocculation mechanisms and resulting floc characteristics.  

PubMed

Electrocoagulation (EC) and chemical coagulation (CC) are employed in water treatment for particle removal. Although both are used for similar purposes, they differ in their dosing method - in EC the coagulant is added by electrolytic oxidation of an appropriate anode material, while in CC dissolution of a chemical coagulant is used. These different methods in fact induce different chemical environments, which should impact coagulation/flocculation mechanisms and subsequent floc formation. Hence, the process implications when choosing which to apply should be significant. This study elucidates differences in coagulation/flocculation mechanisms in EC versus CC and their subsequent effect on floc growth kinetics and structural evolution. A buffered kaolin suspension served as a representative solution that underwent EC and CC by applying aluminum via additive dosing regime in batch mode. In EC an aluminum anode generated the active species while in CC, commercial alum was used. Aluminum equivalent doses were applied, at initial pH values of 5, 6.5 and 8, while samples were taken over pre-determined time intervals, and analyzed for pH, particle size distribution, ? potential, and structural properties. EC generated fragile flocs, compared to CC, over a wider pH range, at a substantially higher growth rate, that were prone to restructuring and compaction. The results suggest that the flocculation mechanism governing EC in sweep floc conditions is of Diffusion Limited Cluster Aggregation (DCLA) nature, versus a Reaction Limited Cluster Aggregation (RLCA) type in CC. The implications of these differences are discussed. PMID:22525456

Harif, Tali; Khai, Moti; Adin, Avner

2012-06-15

332

Random walks and the additive coagulation equation  

NASA Astrophysics Data System (ADS)

Numerical simulations of hierarchical gravitational clustering in an expanding universe show that, as time evolves, small clusters merge with each other to form larger clusters, whereas fragmentation of clusters is relatively uncommon. Stochastic models of the hierarchical clustering process can provide insight into, as well as useful approximations to, the evolution measured in these simulations. The Poisson random walk excursion model, the Poisson Galton-Watson branching process, and the monodisperse additive coagulation equation are three examples of such stochastic models. When initially identical particles cluster from an initially Poisson spatial distibution, all three approaches give essentially the same description of how clusters grow. This paper shows that clustering from an initially Poisson distribution in which the initial particles do not all have the same mass can be described by simple generalizations of the models above. Such an initial distribution is said to be `compound Poisson'. Therefore, excursions of random walks associated with compound Poisson distributions are studied here. In such an excursion set model, clusters grow in essentially the same way as they do in the polydisperse additive coagulation model. Thus, the interrelations between excursion set, branching process and coagulation models of clustering, associated with the Poisson distribution, also apply to compound Poisson distributions. This means that, within the context of these models, when the initial conditions are compound Poisson then merger and accretion rates, and the entire merger history tree, can all be written analytically, just as for clustering from Poisson initial conditions.

Sheth, Ravi K.

1998-04-01

333

Can dust coagulation trigger streaming instability?  

NASA Astrophysics Data System (ADS)

Context. Streaming instability can be a very efficient way of overcoming growth and drift barriers to planetesimal formation. However, it was shown that strong clumping, which leads to planetesimal formation, requires a considerable number of large grains. State-of-the-art streaming instability models do not take into account realistic size distributions resulting from the collisional evolution of dust. Aims: We investigate whether a sufficient quantity of large aggregates can be produced by sticking and what the interplay of dust coagulation and planetesimal formation is. Methods: We develop a semi-analytical prescription of planetesimal formation by streaming instability and implement it in our dust coagulation code based on the Monte Carlo algorithm with the representative particles approach. Results: We find that planetesimal formation by streaming instability may preferentially work outside the snow line, where sticky icy aggregates are present. The efficiency of the process depends strongly on local dust abundance and radial pressure gradient, and requires a super-solar metallicity. If planetesimal formation is possible, the dust coagulation and settling typically need ~100 orbits to produce sufficiently large and settled grains and planetesimal formation lasts another ~1000 orbits. We present a simple analytical model that computes the amount of dust that can be turned into planetesimals given the parameters of the disk model.

Dr??kowska, J.; Dullemond, C. P.

2014-12-01

334

Heparanase and Coagulation-New Insights  

PubMed Central

Heparanase, a ?-D-endoglucuronidase abundant in platelets that was discovered 30 years ago, is an enzyme that cleaves heparan sulfate side chains on the cell surface and in the extracellular matrix. It was later recognized as being a pro-inflammatory and pro-metastatic protein. We had earlier demonstrated that heparanase may also affect the hemostatic system in a non-enzymatic manner. We had shown that heparanase up-regulated the expression of the blood coagulation initiator tissue factor (TF) and interacted with the tissue factor pathway inhibitor (TFPI) on the cell surface membrane of endothelial and tumor cells, leading to dissociation of TFPI and resulting in increased cell surface coagulation activity. Moreover, we have demonstrated that heparanase directly enhanced TF activity which led to increased factor Xa production and subsequent activation of the coagulation system. Recently, heparanase inhibitory peptides derived of TFPI-2 were demonstrated by us to inhibit heparanase procoagulant activity and attenuate sepsis in mouse models. PMID:25386347

Nadir, Yona

2014-01-01

335

Activation of endothelial intrinsic NF-?B pathway impairs protein C anticoagulation mechanism and promotes coagulation in endotoxemic mice  

PubMed Central

Although the role of systemic activation of the nuclear factor ?B (NF-?B) pathway in septic coagulation has been well documented, little is known about the contribution of endothelial-specific NF-?B signaling in this pathologic process. Here, we used transgenic mice that conditionally overexpress a mutant I-?B?, an inhibitor of NF-?B, selectively on endothelium, and their wild-type littermates to define the role of endothelial-specific NF-?B in septic coagulation. In wild-type mice, lipopolysaccharide (LPS) challenge (5 mg/kg intraperitoneally) caused markedly increased plasma markers of coagulation, decreased plasma fibrinogen level, and widespread tissue fibrin deposition, which were abrogated by endothelial NF-?B blockade in transgenic mice. Endothelial NF-?B blockade inhibited tissue factor expression in endothelial cells, but not in leukocytes. Endothelial NF-?B blockade did not inhibit LPS-induced tissue factor expression in heart, kidney, and liver. Endothelial NF-?B blockade prevented LPS down-regulation of endothelial protein C receptor (EPCR) and thrombomodulin protein expressions, inhibited tissue tumor necrosis factor-? converting enzyme activity, reduced EPCR shedding, and restored plasma protein C level. Our data demonstrate that endothelial intrinsic NF-?B signaling plays a pivotal role in septic coagulation and suggests a link between endothelial-specific NF-?B activation and the impairment of the thrombomodulin-protein C-EPCR anticoagulation pathway. PMID:19620400

Song, Dongmei; Ye, Xiaobing; Xu, Honglei

2009-01-01

336

Heat transfer to a single particle exposed to a thermal plasma  

Microsoft Academic Search

This paper is concerned with an analytical study of the heat and mass transfer process of a single particle exposed to a thermal plasma, with emphasis on the effects which evaporation imposes on heat transfer from the plasma to the particle. The results refer mainly to an atmospheric-pressure argon plasma and, for comparison purposes, an argon-hydrogen mixture and a nitrogen

Xi Chen; E. Pfender

1982-01-01

337

A novel ?-fluidic whole blood coagulation assay based on Rayleigh surface-acoustic waves as a point-of-care method to detect anticoagulants  

PubMed Central

A universal coagulation test that reliably detects prolonged coagulation time in patients, irrespective of the anticoagulant administered, has not been available to date. An easily miniaturised, novel ?-fluidic universal coagulation test employing surface acoustic waves (SAW) is presented here. SAW was employed to instantly mix and recalcify 6??l citrated whole blood and image correlation analysis was used to quantify clot formation kinetics. The detection of clinically relevant anticoagulant dosing with old anticoagulants (unfractionated heparin, argatroban) and new anticoagulants (dabigatran, rivaroxaban) has been tested and compared to standard plasma coagulation assays. The applicability of this novel method has been confirmed in a small patient population. Coagulation was dose-proportionally prolonged with heparin, argatroban, dabigatran, and rivaroxaban, comparable to standard tests. Aspirin and clopidogrel did not interfere with the SAW-induced clotting time (SAW-CT), whereas the strong GPIIb/IIIa-inhibitor abciximab did interfere. Preliminary clinical data prove the suitability of the SAW-CT in patients being treated with warfarin, rivaroxaban, or dabigatran. The system principally allows assessment of whole blood coagulation in humans in a point-of-care setting. This method could be used in stroke units, emergency vehicles, general and intensive care wards, as well as for laboratory and home testing of coagulation. PMID:24404078

Meyer dos Santos, Sascha; Zorn, Anita; Guttenberg, Zeno; Picard-Willems, Bettina; Klaffling, Christina; Nelson, Karen; Klinkhardt, Ute; Harder, Sebastian

2013-01-01

338

Depletion of extrinsic pathway inhibitor (EPI) sensitizes rabbits to disseminated intravascular coagulation induced with tissue factor: evidence supporting a physiologic role for EPI as a natural anticoagulant.  

PubMed Central

Although in vitro experiments have established that extrinsic pathway inhibitor (EPI) is the only known plasma inhibitor of factor VIIa-tissue factor (TF) catalytic activity of potential physiologic significance, evidence of its function in vivo has been lacking. TF-induced intravascular coagulation may occur in patients despite normal plasma levels of EPI and, in our earlier studies, normal plasma EPI levels did not protect rabbits from intravascular coagulation induced by an infusion of purified TF (1 microgram/kg). Studies have now been carried out in which plasma EPI levels were reduced in rabbits to below 20% of the initial level by injection of anti-rabbit EPI IgG. Infusion into such animals of purified rabbit TF apoprotein (0.25 microgram/kg) reconstituted into phospholipid vesicles induced substantial disseminated intravascular coagulation. Infusion of control saline or phospholipid vesicles not containing TF was without significant effect as was infusion of TF (0.25 microgram/kg) into animals injected with nonimmune goat IgG. These data establish that EPI can dampen TF-induced intravascular coagulation in rabbits. They support the hypothesis that EPI plays a significant role in regulating coagulation resulting from the exposure of blood to trace concentrations of TF during the illnesses and minor injuries of normal existence. Images PMID:1899482

Sandset, P M; Warn-Cramer, B J; Rao, L V; Maki, S L; Rapaport, S I

1991-01-01

339

Characterization of platelet aminophospholipid externalization reveals fatty acids as molecular determinants that regulate coagulation  

PubMed Central

Aminophospholipid (APL) trafficking across the plasma membrane is a key event in cell activation, apoptosis, and aging and is required for clearance of dying cells and coagulation. Currently the phospholipid molecular species externalized are unknown. Using a lipidomic method, we show that thrombin, collagen, or ionophore-activated human platelets externalize two phosphatidylserines (PSs) and five phosphatidylethanolamines (PEs). Four percent of the total cellular PE/PS pool (?300 ng/2 × 108 cells, thrombin), is externalized via calcium mobilization and protease-activated receptors-1 and -4, and 48% is contained in microparticles. Apoptosis and energy depletion (aging) externalized the same APLs in a calcium-dependent manner, and all stimuli externalized oxidized phospholipids, termed hydroxyeicosatetraenoic acid-PEs. Transmembrane protein-16F (TMEM-16F), the protein mutated in Scott syndrome, was required for PE/PS externalization during thrombin activation and energy depletion, but not apoptosis. Platelet-specific APLs optimally supported tissue factor-dependent coagulation in human plasma, vs. APL with longer or shorter fatty acyl chains. This finding demonstrates fatty acids as molecular determinants of APL that regulate hemostasis. Thus, the molecular species of externalized APL during platelet activation, apoptosis, and energy depletion were characterized, and their ability to support coagulation revealed. The findings have therapeutic implications for bleeding disorders and transfusion therapy. The assay could be applied to other cell events characterized by APL externalization, including cell division and vesiculation. PMID:23530199

Clark, Stephen R.; Thomas, Christopher P.; Hammond, Victoria J.; Aldrovandi, Maceler; Wilkinson, Gavin W.; Hart, Keith W.; Murphy, Robert C.; Collins, Peter W.; O’Donnell, Valerie B.

2013-01-01

340

Performance of a uranium liquid argon calorimeter  

SciTech Connect

We present results on the performance of a uranium and liquid argon calorimeter in the NW test beam at Fermilab. We describe the calorimeter, and discuss its performance with electrons, pions and muons from 10 GeV to 150 GeV. The performance perameters measured include response, linearity, resolution, compensation, and e/..pi.. separation.

Tuts, P.M.

1986-01-01

341

The ATLAS liquid-argon electromagnetic calorimeter  

NASA Astrophysics Data System (ADS)

Using test-beam results from the RD3 collaboration, the ATLAS liquid-argon electromagnetic calorimeter has been optimized for the search for the decay of the Higgs boson in two photons. Other physics topics add fewer constraints. We present the choices made for the following items: lead thickness, sampling depth, implementation of the preshower and high-granularity sections.

Zolnierowski, Yves; Atlas Collaboration

1996-12-01

342

Influence of argon and oxygen on charge-state-resolved ion energydistributions of filtered aluminum arcs  

SciTech Connect

The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as well as a narrow IED. These data may enable tailoring thin-film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.

Rosen, Johanna; Anders, Andre; Mraz, Stanislav; Atiser, Adil; Schneider, Jochen M.

2006-03-23

343

Intranasal exposure to amorphous nanosilica particles could activate intrinsic coagulation cascade and platelets in mice  

PubMed Central

Background Nanomaterials with particle sizes <100 nm have been already applied in various applications such as cosmetics, medicines, and foods. Therefore, ensuring the safety of nanomaterials is becoming increasingly important. Here we examined the localization and biological responses of intranasally administered amorphous nanosilica particles in mice, focusing on the coagulation system. Methods We used nanosilica particles with diameters of 30, 70, or 100 nm (nSP30, nSP70, or nSP100 respectively), and conventional microscale silica particles with diameters of 300 or 1000 nm (mSP300 or mSP1000, respectively). BALB/c mice were intranasally exposed to nSP30, nSP70, nSP100, mSP300, or mSP1000 at concentrations of 500 ?g/mouse for 7 days. After 24 hours of last administration, we performed the in vivo transmission electron microscopy analysis, hematological examination and coagulation tests. Results In vivo transmission electron microscopy analysis showed that nanosilica particles with a diameter <100 nm were absorbed through the nasal cavity and were distributed into liver and brain. Hematological examination and coagulation tests showed that platelet counts decreased and that the activated partial thromboplastin time was prolonged in nSP30 or nSP70-treated groups of mice, indicating that nanosilica particles might have activated a coagulation cascade. In addition, in in vitro activation tests of human plasma, nanosilica particles had greater potential than did conventional microscale silica particles to activate coagulation factor XII. In nanosilica-particle-treated groups, the levels of soluble CD40 ligand, and von Willebrand factor which are involved in stimulating platelets tended to slightly increase with decreasing particle size. Conclusions These results suggest that intranasally administered nanosilica particles with diameters of 30 and 70 nm could induce abnormal activation of the coagulation system through the activation of an intrinsic coagulation cascade. This study provides information to advance the development of safe and effective nanosilica particles. PMID:23958113

2013-01-01

344

Examination of scattering volume aligment in Thomson scattering off of a shock front in argon  

SciTech Connect

Thomson scattering in argon gas successfully probed the region of plasma just behind the shock front. The instantaneous shock velocity can be inferred from the duration of the signal, taking into account the size and shape of the scattering volume. Possible misalignment of the probe beam and spectrometer slits greatly affects the size and shape of the scattering volume, and therefore affects the calculation of the instantaneous shock velocity.

Reighard, A B; Froula, D H; Drake, R P; Ross, J S; Divol, L

2007-07-26

345

46 CFR 151.50-36 - Argon or nitrogen.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36...Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable...

2012-10-01

346

46 CFR 151.50-36 - Argon or nitrogen.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36...Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable...

2011-10-01

347

46 CFR 151.50-36 - Argon or nitrogen.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36...Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable...

2010-10-01

348

Comparing the equivalent particle number density distribution of gas and plasma flow fields.  

PubMed

In this paper, the equivalent particle number density distribution of gas and plasma flow fields is investigated. For the purpose of facilitating comparison, argon gas and argon arc plasma are chosen as practical examples for experiment. The equivalent particle number density distributions of the argon gas and argon arc plasma are reconstructed from the experimentally measured refractive index distributions obtained by moiré tomography, while five cross sections, which are 7, 8.5, 10, 11.5, and 13 mm away from the jet nozzle are chosen for practical calculation and comparison. In experiment, the probe wavelength and the export pressure of argon gas and argon arc plasma are the same. The experimental results manifest that (1) the equivalent particle number density decreases with the distance away from the jet nozzle of the gas flow field, while (2) the equivalent particle number density of the plasma flow field has a different variation. Finally, the experimental results are theoretically explained and analyzed. PMID:23669673

Chen, Yun-yun; Zhang, Ying-ying; Zhang, Cheng-yi; Li, Zhen-hua

2013-04-20

349

Chronic HIV Disease and Activation of the Coagulation System  

PubMed Central

With current effective antiretroviral treatment, the spectrum of morbidity and mortality during chronic HIV disease has shifted away from AIDS defining clinical events. Persistent abnormalities in coagulation appear to contribute to excess risk for a broad spectrum of non-AIDS defining complications, including, but not limited to, venous and arterial thrombotic disease. Mechanisms specific to HIV disease, antiretroviral therapy, and lifestyle or behavioral factors contribute to a pro-coagulant state, in part, through increased tissue factor activity coupled with a paradoxical decline in the anti-coagulant response. Alterations in coagulation biology in the context of HIV disease appear to be largely a consequence of persistent systemic immune activation, micro- and macro-vascular disease, and, potentially, impaired hepatic synthesis of coagulation factors. The clinical consequences of HIV-related changes in coagulation biology, the degree to which they are unique to HIV disease, and whether they can be mitigated through adjunct treatments, remains a focus of current research. PMID:24034985

Baker, Jason V.

2014-01-01

350

The Interface between Inflammation and Coagulation in Cardiovascular Disease  

PubMed Central

The intimate connection between coagulation and inflammation in the pathogenesis of vascular disease has moved more and more into focus of clinical research. This paper focuses on the essential components of this interplay in the settings of cardiovascular disease and acute coronary syndrome. Tissue factor, the main initiator of the extrinsic coagulation pathway, plays a central role via causing a proinflammatory response through activation of coagulation factors and thereby initiating coagulation and downstream cellular signalling pathways. Regarding activated clotting factors II, X, and VII, protease-activated receptors provide the molecular link between coagulation and inflammation. Hereby, PAR-1 displays deleterious as well as beneficial properties. Unravelling these interrelations may help developing new strategies to ameliorate the detrimental reciprocal aggravation of inflammation and coagulation. PMID:22518344

Demetz, Gabriele; Ott, Ilka

2012-01-01

351

A microwave plasma cleaning apparatus  

NASA Technical Reports Server (NTRS)

In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films (less than or equal to 20 micrometers in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-m torr) argon/oxygen plasmas were as high as 2.7 micrometers/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

Tsai, C. C.; Nelson, W. D.; Schechter, D. E.; Thompson, L. M.; Glover, A. L.

1995-01-01

352

A microwave plasma cleaning apparatus  

SciTech Connect

In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films ({le} 20 {micro}m in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-mtorr) argon/oxygen plasmas were as high as 2.7 {micro}m/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

Tsai, C.C.; Nelson, W.D.; Schechter, D.E. [Oak Ridge National Lab., TN (United States); Thompson, L.M.; Glover, A.L. [Oak Ridge Y-12 Plant, TN (United States)

1994-12-31

353

Pre-coagulation for microfiltration of an upland surface water  

Microsoft Academic Search

The effect of different coagulants on cake formation and hydraulic resistance in membrane filtration of strongly coloured (SUVA?4.8) upland surface water has been studied at bench-scale under constant pressure conditions. Coagulants used were aluminium sulphate, polyaluminium chloride, ferric chloride and ferric sulphate. Optimisation of coagulation parameters was carried by conventional jar testing. The R?c (specific cake resistance in m?2) values

A. T. Pikkarainen; S. J. Judd; J. Jokela; L. Gillberg

2004-01-01

354

Bipolar coagulation of vessels in aesthetic plastic surgery.  

PubMed

Bipolar coagulation for hemostasis should be used more frequently than monopolar coagulation in aesthetic plastic surgery. The advantages of the procedure are manifold: considerable reduction of the amount of current, and consequent prevention of deleterious effects on other tissues and organs; minimal devitalization of tissues during coagulation; reduction of reactive edema; total separation of the patient from the power source when coagulating forceps are not in use; avoidance of burns due to defective insulation of conductors; elimination of "spark" burns of the surgeon's fingers through punctured gloves; and freedom of the assistants' hands for other duties. PMID:24173844

Marino, H; Marino, H

1978-12-01

355

Improving the efficiency of clarifiers for coagulation treatment of water  

NASA Astrophysics Data System (ADS)

Technological and design possibilities of improving clarifiers for coagulation treatment of water are considered. The results obtained from implementing these possibilities in real devices are presented.

Vinogradov, V. N.; Smirnov, B. A.; Zhadan, A. V.; Avan, V. K.

2010-08-01

356

Recovery of struvite via coagulation and flocculation using natural compounds.  

PubMed

One of the major setbacks of struvite recovery processes is the difficulty in harvesting struvite crystals. This study evaluates the use of different coagulants to improve precipitation of struvite (MgNH4PO4.6H20) crystals. Chitosan and poly(diallyldimethyl ammonium chloride) (Poly-DADMAC) as a coagulant-flocculent and alginate and bentonite as a coagulant aid have been examined in jar tests. Also, a continuous three-phase process, i.e., struvite crystallization, coagulation/flocculation and precipitation process, was set up for real wastewater. Addition of chitosan as the coagulant and bentonite as the coagulant aid was significantly more efficient in forming struvite flocs in comparison to Poly-DADMAC alone or with coagulant aid, which did not show any positive effect. The calculated average settling velocity of struvite with chitosan-bentonite addition in synthetic and in real wastewater increased by approximately 5.3 and 2.8 folds, respectively, compared with that of no coagulant/flocculent addition. Phosphorus recovery of over 70% was achieved by the continuous process. Findings in this study clearly confirmed the possibility of using chitosan and bentonite as an efficient coagulant-flocculent to enhance the recovery of struvite crystals. PMID:25145182

Latifian, Maryam; Liu, Jing; Mattiasson, Bo

2014-01-01

357

Metrology in arc plasma: a new cathode  

Microsoft Academic Search

A new cathode shape has improved the stability and reproducibility of the ultraviolet continuum emitted by the plasma of a miniature argon arc. This arc is used as a transfer standard of spectral radiance in the vacuum ultraviolet.

R Croche

1980-01-01

358

Dust coagulation in protoplanetary disks: porosity matters  

E-print Network

Context: Sticking of colliding dust particles through van der Waals forces is the first stage in the grain growth process in protoplanetary disks, eventually leading to the formation of comets, asteroids and planets. A key aspect of the collisional evolution is the coupling between dust and gas motions, which depends on the internal structure (porosity) of aggregates. Aims: To quantify the importance of the internal structure on the collisional evolution of particles, and to create a new coagulation model to investigate the difference between porous and compact coagulation in the context of a turbulent protoplanetary disk. Methods: We have developed simple prescriptions for the collisional evolution of porosity of grain-aggregates in grain-grain collisions. Three regimes can then be distinguished: `hit-and-stick' at low velocities, with an increase in porosity; compaction at intermediate velocities, with a decrease of porosity; and fragmentation at high velocities. (..) Results: (..) We can discern three different stages in the particle growth process (..) We find that when compared to standard, compact models of coagulation, porous growth delays the onset of settling, because the surface area-to-mass ratio is higher, a consequence of the build-up of porosity during the initial stages. As a result, particles grow orders of magnitudes larger in mass before they rain-out to the mid-plane. Depending on the turbulent viscosity and on the position in the nebula, aggregates can grow to (porous) sizes of ~ 10 cm in a few thousand years. We also find that collisional energies are higher than in the limited PCA/CCA fractal models, thereby allowing aggregates to restructure. It is concluded that the microphysics of collisions plays a key role in the growth process.

C. W. Ormel; M. Spaans; A. G. G. M. Tielens

2006-10-02

359

Dissociation-excitation reactions of argon metastables with carbon dioxide.  

NASA Technical Reports Server (NTRS)

Results of a study showing that a metastable argon-carbon dioxide reaction results in dissociation of carbon dioxide and electronic excitation of one of the products, carbon monoxide or oxygen. A flow system using a 2450-MHz discharge was used to produce metastable argon atoms. Metastable argon in the afterglow was confirmed by adding nitrogen to the afterglow. Without addition of carbon dioxide no argon line emission, or any other emission, is observed from the reaction zone. Absence of argon line emission produced by recombination indicates the absence of charged species.

Starr, W. L.

1971-01-01

360

Argon recovery from partial oxidation based ammonia plant purge gases  

SciTech Connect

This patent describes a method for recovering argon from a feed mixture comprising argon, carbon monoxide, methane, hydrogen, and nitrogen. It comprises passing the feed mixture through a pressure swing adsorption system to remove carbon monoxide, methane and part of the nitrogen thereby producing a fraction containing an increased amount of argon; and passing the argon fraction to a cryogenic fractional distillation system to remove hydrogen and the remaining nitrogen in the fraction as a distillate product and to produce a pure argon product.

Krishnamurthy, R.; Andrecovich, M.J.; MacLean, D.L.; Wright, K.J.

1992-03-31

361

Optimized alumina coagulants for water treatment  

Microsoft Academic Search

Substitution of a single Ga-atom or single Ge-atom (GaAl.sub.12 and GeAl.sub.12 respectively) into the center of an aluminum Keggin polycation (Al.sub.13) produces an optimal water-treatment product for neutralization and coagulation of anionic contaminants in water. GaAl.sub.12 consistently shows .about.1 order of magnitude increase in pathogen reduction, compared to Al.sub.13. At a concentration of 2 ppm, GaAl.sub.12 performs equivalently to 40

May D. Nyman; Thomas A. Stewart

2012-01-01

362

Natural organic matter removal and enhanced coagulation as a link between coagulation and electrocoagulation  

Microsoft Academic Search

Although coagulation has historically been used for turbidity removal, drinking water regulations have emerged in recent years expanding the use of this process beyond its traditional role to include disinfection by-products (DBP) precursors removal. Effective removal of DBP precursors is the one of the major challenges in modern drinking water treatment. DBP precursors are present in all surface water supplies

Djamel Ghernaouta; Badiaa Ghernaoutb; Amara Kellil

2009-01-01

363

Effect of Copper(II) on Natural Organic Matter Removal During Drinking Water Coagulation Using Aluminum-Based Coagulants  

Microsoft Academic Search

Coagulation has been proposed as a best available technology for controlling natural organic matter (NOM) during drinking water treatment. The presence of heavy metals such as copper(II) in source water, which may form copper-NOM complexes and\\/or interact with a coagulant, may pose a potential challenge on the coagulation of NOM. In this work, the effect of copper(II) on NOM removal

Guojing Liu; Xiangru Zhang; Jeffrey W. Talley

2007-01-01

364

Preparation and coagulation efficiency of polyaluminium ferric silicate chloride composite coagulant from wastewater of high-purity graphite production.  

PubMed

The aim of the present work was to produce a polyaluminium ferric silicate chloride (PAFSiC) coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride (PAC). The PAFSiC coagulant was prepared by co-polymerization. The effects of (Al+Fe)/Si molar ratio, OH/(Al+Fe) molar ratio (i.e., y value), coagulant dosage and pH value of test suspension on the coagulation behavior of FAFSiC and the stability of the PAFSiC were also examined. Results showed that PAFSiC performed more efficiently than PAC in removing turbidity, chemical oxygen demand (COD), and total phosphate (TP). The PAFSiC with a y value of 2.0 and (Al+Fe)/Si ratio of 5 (PAFSiC 2.0/5) showed excellent coagulation effect for both turbidity and COD, while PAFSiC 1.0/5 was the best for TP. The optimum coagulation pH range of PAFSiC 2.0/5 was 5.0-9.0, slightly wider than that of PAC (6.0-8.0). The process can be easily incorporated into high-purity graphite production plants, thereby reducing wastewater pollution and producing a valuable coagulant. PMID:22125904

Niu, Xiaoxia; Li, Xili; Zhao, Jihong; Ren, Yigang; Yang, Yanqin

2011-01-01

365

Preparation, morphology and coagulation characteristics of a new polyferric chloride coagulant prepared using pyrite cinders.  

PubMed

Pyrite cinders are the main industrial waste generated from the process of sulphuric acid production using pyrite ores. The pyrite cinders may have utilization value in preparing a new polyferric chloride (PFC) coagulant. In order to attain this objective, a preparation method for PFC products from pyrite cinders was studied by a Taguchi orthogonal array experiment. On the basis of the successful preparation, the morphologies and coagulation characteristics of three PFC products, with different basicities, were observed by transmission electron microscopy (TEM) and examined by jar tests, respectively. The results showed that the molar ratio of NaOH to Fe should be in a range between 0.75:1 and 1:1, the molar ratio of stabilizer NaH2PO4 to Fe should be in a range between 0.12:1 and 0.15:1, the curing time should be 2 h, the curing temperature can be 60 degrees C and the molar ratio of NaHCO3 to Fe can be determined according to the basicity required in order to get the optimal stability of PFC products and the best flocculation efficiency. Although the degree of aggregation of the PFC products became larger with the increase in the basicity, the coagulation efficiency could be only improved with an increase in the basicity within a certain range. When the basicity exceeded a certain value, the coagulation efficiency started to decrease. In this study, PFC2 (B = 11.16%) had better coagulation characteristics than either PFCl (B = 6.08%), PFC2 (B = 11.16%), PFC3 (B = 15.92%) or polyaluminium chloride (PAC). PMID:21879566

Li, W; Hua, T; Zhou, Q X

2011-01-01

366

Staphylococcal Superantigen-like Protein 10 (SSL10) Inhibits Blood Coagulation by Binding to Prothrombin and Factor Xa via Their ?-Carboxyglutamic Acid (Gla) Domain*  

PubMed Central

The staphylococcal superantigen-like protein (SSL) family is composed of 14 exoproteins sharing structural similarity with superantigens but no superantigenic activity. Target proteins of four SSLs have been identified to be involved in host immune responses. However, the counterparts of other SSLs have been functionally uncharacterized. In this study, we have identified porcine plasma prothrombin as SSL10-binding protein by affinity purification using SSL10-conjugated Sepharose. The resin recovered the prodomain of prothrombin (fragment 1 + 2) as well as factor Xa in pull-down analysis. The equilibrium dissociation constant between SSL10 and prothrombin was 1.36 × 10?7 m in surface plasmon resonance analysis. On the other hand, the resin failed to recover ?-carboxyglutamic acid (Gla) domain-less coagulation factors and prothrombin from warfarin-treated mice, suggesting that the Gla domain of the coagulation factors is essential for the interaction. SSL10 prolonged plasma clotting induced by the addition of Ca2+ and factor Xa. SSL10 did not affect the protease activity of thrombin but inhibited the generation of thrombin activity in recalcified plasma. S. aureus produces coagulase that non-enzymatically activates prothrombin. SSL10 attenuated clotting induced by coagulase, but the inhibitory effect was weaker than that on physiological clotting, and SSL10 did not inhibit protease activity of staphylothrombin, the complex of prothrombin with coagulase. These results indicate that SSL10 inhibits blood coagulation by interfering with activation of coagulation cascade via binding to the Gla domain of coagulation factor but not by directly inhibiting thrombin activity. This is the first finding that the bacterial protein inhibits blood coagulation via targeting the Gla domain of coagulation factors. PMID:23754290

Itoh, Saotomo; Yokoyama, Ryosuke; Kamoshida, Go; Fujiwara, Toshinobu; Okada, Hiromi; Takii, Takemasa; Tsuji, Tsutomu; Fujii, Satoshi; Hashizume, Hideki; Onozaki, Kikuo

2013-01-01

367

Collisional radiative model of an argon atmospheric capillary surface-wave discharge  

SciTech Connect

The characteristics of a microwave surface-wave sustained plasma operated at atmospheric pressure in an open-ended dielectric tube are investigated theoretically as a first step in the development of a self-consistent model for these discharges. The plasma column is sustained in flowing argon. A surface-wave discharge that fills the whole radial cross section of the discharge tube is considered. With experimental electron temperature profiles [Garcia et al., Spectrochim. Acta, Part B 55, 1733 (2000)] the numerical model is used to test the validity of the different approximations and to study the influence of the different kinetic processes and power loss mechanisms on the discharge.

Yanguas-Gil, A.; Cotrino, J.; Gonzalez-Elipe, A.R. [Instituto de Ciencias de Materiales and Departamentos de Fisica Atomica, Molecular y Nuclear and Quimica Inorganica (CSIC-Universidad de Sevilla), Sevilla (Spain)

2004-12-01

368

Argon: Performance Insulation for Shared Storage Servers  

Microsoft Academic Search

Services that share a storage system should realize the same efficiency, within their share of time, as when they have the system to themselves. The Argon storage server explicitlymanages its resourcesto boundthe inefficiency arising from inter-service disk and cache interference in traditional systems. The goal is to provide each ser- vice with at least a configured fraction (e.g., 0.9) of

Matthew Wachs; Michael Abd-El-Malek; Eno Thereska; Gregory R. Ganger

2007-01-01

369

Oxygen discharges diluted with argon: dissociation processes  

Microsoft Academic Search

We use a global (volume averaged) model to study the dissociation processes and the presence of negative ions and metastable species in a low pressure high density O2\\/Ar discharge in the pressure range 1-100 mTorr. The electron density and the fractional dissociation of the oxygen molecule increases with increased argon content in the discharge. We relate this increase in fractional

J. T. Gudmundsson; E. G. Thorsteinsson

2007-01-01

370

Oxygen discharges diluted with argon: dissociation processes  

Microsoft Academic Search

We use a global (volume averaged) model to study the dissociation processes and the presence of negative ions and metastable species in a low pressure high density O2\\/Ar discharge in the pressure range 1–100 mTorr. The electron density and the fractional dissociation of the oxygen molecule increases with increased argon content in the discharge. We relate this increase in fractional

J T Gudmundsson; E G Thorsteinsson

2007-01-01

371

Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy  

NASA Astrophysics Data System (ADS)

An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of ˜2 × 1013 cm-3, argon metastable densities ˜1014 cm-3 and a reduced electric field about 10 Td are determined.

Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

2013-11-01

372

Coagulation in aortofemoral bifurcation bypass grafting.  

PubMed

Few data are available on the pathophysiology of the coagulation system during aortic surgery. Cross-clamping of the aorta, intestinal eventeration and circulatory shock in ruptured aortic aneurysms are thought to cause coagulation disturbances and hyperfibrinolysis. A prospective study of several parameters of the clotting system, i.e. standard clotting tests, platelet count, indicators of fibrinolysis, inhibitors of the clotting cascade and proteases were measured perioperatively in aortobifemoral bypass grafts. Ten patients undergoing elective procedures and two emergency cases with ruptured aortic aneurysms were included. The standard clotting tests reflected the use of heparin. A similar course of ATIII, C1-inhibitor, alpha 2-antiplasmin, plasminogen and fibrinogen with a decrease during the operation and a return to almost normal values postoperatively, were due to intra-operative blood loss, haemodilution and a slight activation of the clotting cascade, as well as, hyperfibrinolysis. This observation was supported by the increased levels of euglobulin lysis and PMN-elastase and the resultant increase in some fibrinogen degradation products, indicating non-specific proteolysis. These changes were more pronounced in the two emergency cases, except for the heparin induced changes in PTT and thrombin time. It is concluded that non-specific proteolysis may be an important factor in the pathogenesis of clotting disorders in surgery of the aorta. Further research is needed to discover the pathways of non-specific proteolysis and its prevention by protease inhibitors. PMID:1864390

von Sommoggy, S; Fraunhofer, S; Wahba, A; Blümel, G; Maurer, P C

1991-06-01

373

Insights into discharge argon mediated biofilm inactivation  

PubMed Central

Formation of bacterial biofilms at solid-liquid interfaces creates numerous problems in biomedical sciences. Conventional sterilization and decontamination methods are not suitable for new and more sophisticated biomaterials. In this paper, the efficiency and effectiveness of gas discharges in inactivation and removal of biofilms on biomaterials were studied. We found that although discharge oxygen, nitrogen and argon all demonstrated excellent antibacterial and antibiofilm activity, gases with distinct chemical/physical properties underwent different mechanisms of action. Discharge oxygen and nitrogen mediated decontamination was associated with strong etching effects, which can cause live bacteria relocation and thus contamination spreading. On the contrary, although discharge argon at low powers maintained excellent antibacterial ability, it had negligible etching effects. Based on these results, an effective decontamination approach using discharge argon was established in which bacteria and biofilms were killed in situ and then removed from contaminated biomaterials. This novel procedure is applicable for a wide range of biomaterials and biomedical devices in an in vivo and clinical setting. PMID:24070412

Traba, Christian; Chen, Long; Liang, Danni; Azzam, Robin; Liang, Jun F.

2014-01-01

374

21 CFR 864.5425 - Multipurpose system for in vitro coagulation studies.  

Code of Federal Regulations, 2011 CFR

...system for in vitro coagulation studies. 864.5425 Section 864...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY...system for in vitro coagulation studies. (a) Identification...system for in vitro coagulation studies is a device consisting...

2011-04-01

375

21 CFR 864.5425 - Multipurpose system for in vitro coagulation studies.  

Code of Federal Regulations, 2013 CFR

...system for in vitro coagulation studies. 864.5425 Section 864...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY...system for in vitro coagulation studies. (a) Identification...system for in vitro coagulation studies is a device consisting...

2013-04-01

376

The modeling of arsenic removal from contaminated water using coagulation and sorption  

E-print Network

To achieve predictive capability for complex environmental systems with coagulation and arsenic sorption, a unified improved coagulation model coupled with arsenic sorption was developed. A unified coagulation model coupled with arsenic sorption...

Kim, Jin-Wook

2005-11-01

377

Plasma surface cleaning using microwave plasmas  

SciTech Connect

In a microwave electron cyclotron resonance (ECR) plasma source, reactive plasmas of oxygen and its mixture with argon are used for plasma-cleaning experiments. Aluminum test samples (0.95 {times} 1.9 cm) were coated with thin films ({le} 20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in various discharge conditions with fixed microwave power, rf power, biased potential, gas pressures (0.5 and 5 mtorr), and operating time up to 35 min. The status of plasma cleaning has been monitored by using mass spectroscopy. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low pressure (0.5 mtorr) argon/oxygen plasmas were as high as 2.7 {mu}/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces and confirm the effectiveness of plasma cleaning in achieving atomic levels of surface cleanliness. In this paper, significant results are reported and discussed.

Tsai, C.C.; Haselton, H.H.; Nelson, W.D.; Schechter, D.E. [Oak Ridge National Lab., TN (United States); Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M. [Oak Ridge Y-12 Plant, TN (United States)

1993-11-01

378

Metals in airpollution particles decrease whole blood coagulation time  

EPA Science Inventory

The mechanism underlying the pro-coagulative effect of air pollution particle exposure is not known. We tested the postulate that 1) the soluble fraction ofan air pollution particle can affect whole blood coagulation time and 2) metals included in the soluble fraction are respons...

379

Removal of THM precursors by coagulation or ion exchange  

Microsoft Academic Search

The removal of natural organic matter (NOM) from drinking water supplies can be achieved by different processes, among them coagulation and adsorption. Synthetic waters made from concentrates of humic substances from reservoir and river waters were tested in the laboratory for ease of removal of NOM by coagulation with cationic organic polymers and with alum, and by adsorption on anion

Brian Bolto; David Dixon; Rob Eldridge; Simon King

2002-01-01

380

The Coagulation of Soot Particles with van der Waals Forces  

Microsoft Academic Search

A detailed calculation of the coagulation kinetics of a soot aerosol has been performed by simulating numerically the coagulation kinetics with the inclusion of van der Waals forces. The van der Waals forces between two soot particles at 1600 K and 1 atmosphere give rise 10 a collision rate enhancement which varies between a maximum of about 2.4 for 1

STEPHEN J. Harris; IAN M. Kennedy

1988-01-01

381

ORIGINAL PAPER Acid coagulation behavior of homogenized milk: effect  

E-print Network

ORIGINAL PAPER Acid coagulation behavior of homogenized milk: effect of interacting and non the early stages of the acid coagulation behavior of milk containing homogenized fat globules. By addition of Tween 20 to homogenized milk, it was possible to create two similar colloidal systems with completely

Paris-Sud XI, Université de

382

Preparation of chitosan filament applying new coagulation system  

Microsoft Academic Search

A new coagulation system for chitosan, aqueous alcohol solution of calcium chloride or acetate, was found and successfully applied for spinning of chitosan filament. FT-IR and atomic absorption spectrophotometric experiments indicated that chitosan coagulation was induced through calcium chelation with amino group of chitosan molecule. The original spun filament was soluble in water because chitosan exists as an acetic acid

Hiroshi Tamura; Yukihiko Tsuruta; Kouki Itoyama; Wannasiri Worakitkanchanakul; Ratana Rujiravanit; Seiichi Tokura

2004-01-01

383

Factors affecting the coagulation of seawater by ferric chloride  

Microsoft Academic Search

The combination of chemical coagulation and membrane filtration (e.g. micro- or ultra- filtration) represents an effective pretreatment for seawater desalination by reverse osmosis (RO). The removal of dissolved organic substances requires optimization in order to enhance treatment performance and minimize the risk of membrane fouling. For this reason a detailed understanding of the performance of hydrolyzing metal salts during coagulation

J. Duan; A. Niu; D. Shi; F. Wilson; N. J. D. Graham

2009-01-01

384

Impact of source water quality on multiwall carbon nanotube coagulation.  

PubMed

Potable water treatment facilities may become an important barrier in limiting human exposure to engineered nanoparticles (ENPs) as ENPs begin to contaminate natural aquatic systems. Coagulation of ENPs will likely be a major process that controls the ENP fate and the subsequent removal in the aqueous phase. The influence that source water quality has on ENP coagulation is still relatively unknown. The current study uses a 2(3) x 2(4-1) fractional factorial design to identify seven key surface water constituents that affect multiwall carbon nanotube (MWCNT) coagulation. These seven factors include: influent concentrations of kaolin, organic matter (OM), alginate, and MWCNTs; type and dosage of coagulant; and method of MWCNT stabilization. MWCNT removal was most affected by coagulant type and dosage, with alum outperforming ferric chloride at circumneutral pH. None of the other factors were universally significant but instead depended on coagulant type, dose, and method of stabilization. In all cases where factors were found to have a significant impact on MWCNT removal, however, the relationship was consistent: higher influent concentrations of kaolin and alginate improved MWCNT removal while higher influent concentrations of OM hindered MWCNT coagulation. Once MWCNTs are released into the natural environment, their coagulation behavior will be determined by the type and quantity of pollutants (i.e., factors) present in the aquatic environment and are governed by the same mechanisms that influence the colloidal stability of "natural" nanoparticles. PMID:20092299

Holbrook, R David; Kline, Carly N; Filliben, James J

2010-02-15

385

Colour removal from landfill leachate by coagulation and flocculation processes  

Microsoft Academic Search

A study was conducted to investigate the efficiency of coagulation and flocculation processes for removing colour from a semi-aerobic landfill leachate from one of the landfill sites in Malaysia. Four types of coagulant namely aluminium (III) sulphate (alum), ferric (III) chloride, ferrous (II) sulphate and ferric (III) sulphate were studied using standard jar test apparatus. Results indicated that ferric chloride

Hamidi Abdul Aziz; Salina Alias; Mohd. Nordin Adlan; Faridah; A. H. Asaari; Mohd. Shahrir Zahari

2007-01-01

386

The scaling attractor and ultimate dynamics for Smoluchowski's coagulation equations  

E-print Network

's coagulation equation for the three simplest rate kernels K(x, y) = 2, x + y and xy. In another work, we (dust and gel). Keywords: dynamic scaling, agglomeration, coagulation, coalescence, infi- nite modulated by a symmetric rate kernel K(x, y). Formally, the evolution equation for the density n(t, x

387

Brain Neoplasms and Coagulation--Lessons from Heterogeneity  

PubMed Central

The coagulation system constitutes an important facet of the unique vascular microenvironment in which primary and metastatic brain tumors evolve and progress. While brain tumor cells express tissue factor (TF) and other effectors of the coagulation system (coagulome), their propensity to induce local and peripheral thrombosis is highly diverse, most dramatic in the case of glioblastoma multiforme (GBM), and less obvious in pediatric tumors. While the immediate medical needs often frame the discussion on current clinical challenges, the coagulation pathway may contribute to brain tumor progression through subtle, context-dependent, and non-coagulant effects, such as induction of inflammation, angiogenesis, or by responding to iatrogenic insults (e.g. surgery). In this regard, the emerging molecular diversity of brain tumor suptypes (e.g. in glioma and medulloblastoma) highlights the link between oncogenic pathways and the tumor repertoire of coagulation system regulators (coagulome). This relationship may influence the mechanisms of spontaneous and therapeutically provoked tumor cell interactions with the coagulation system as a whole. Indeed, oncogenes (EGFR, MET) and tumor suppressors (PTEN, TP53) may alter the expression, activity, and vesicular release of tissue factor (TF), and cause other changes. Conversely, the coagulant microenvironment may also influence the molecular evolution of brain tumor cells through selective and instructive cues. We suggest that effective targeting of the coagulation system in brain tumors should be explored through molecular stratification, stage-specific analysis, and more personalized approaches including thromboprophylaxis and adjuvant treatment aimed at improvement of patient survival. PMID:25386346

D'Asti, Esterina; Fang, Yi; Rak, Janusz

2014-01-01

388

Cost implications of specialized coagulation testing for acute ischemic stroke  

Microsoft Academic Search

Background and Purpose: Hypercoagulable states are a rare but recognized cause of ischemic stroke. Evaluation for these coagulation disorders is costly, but establishing a diagnosis may lead to a change in treatment. We estimated the incremental cost of specialized coagulation testing per additional ischemic stroke patient placed on a regimen of warfarin therapy. Methods: The cost-effectiveness analysis was performed based

Cheryl D. Bushnell; Santanu K. Datta; Larry B. Goldstein

2001-01-01

389

Quality of water treated by coagulation using Moringa oleifera seeds  

Microsoft Academic Search

A model turbid water was treated by coagulation-flocculation and sedimentation, with Moringa oleifera seeds as a coagulant, using jar tests. The quality of the treated water was analyzed and compared with that of the water treated with alum. Experiments were conducted at various dosages of the crude 5% water extract of both dry, shelled and non-shelled Moringa oleifera seeds. Measurements

Anselme Ndabigengesere; K Subba Narasiah

1998-01-01

390

Coagulation of low turbidity surface waters with Moringa oleifera seeds  

Microsoft Academic Search

The use of Moringa oleifera seed extracts both as primary coagulant coagulant aid and its conjunctive use with alum in treating low turbidity waters was studied. The laboratory based studies used the natural polyelectrolyte to treat waters with turbidities between 23 and 90 ntu, obtained from three surface water sources in Kano, Nigeria. On the average, 50% turbidity removal was

Suleyman A. Muyibi; Charles A. Okuofu

1995-01-01

391

Mathematical Modeling and Computer Simulation in Blood Coagulation  

Microsoft Academic Search

Over the last two decades, mathematical modeling has become a popular tool in study of blood coagulation. The in silico methods were able to yield interesting and significant results in the understanding of both individual reaction mechanisms and regulation of large sections of the coagulation cascade. The objective of this paper is to review the development of theoretical research in

Fazoil I. Ataullakhanov; Mikhail A. Panteleev

2005-01-01

392

Disseminated intravascular coagulation in a horse with postpartum ulcerative colitis and laminitis.  

PubMed

Hemostatic studies were conducted on a five year old Belgian mare presented two days postpartum with colic and laminitis that was unresponsive to treatment.The mare was moderately thrombocytopenic with plasma fibrinogen levels more than twice that of a normal control horse. Platelet function as evaluated by aggregometry indicated that the circulating platelets were markedly hyporesponsive. Activated partial thromboplastin times and prothrombin times were prolonged. Para-coagulation tests (protamine sulfate and ethanol gelation) were strongly positive and fibrin degradation products were significantly elevated in the serum.The laboratory data suggested that the clinical bleeding was the result of the development of disseminated intravascular coagulation. The data were compatible with intravascular activation of the clotting mechanism, consumption of hemostatic factors, inhibition of platelet function and enhanced stimulation of the fibrinolytic mechanism.This report illustrates the complexity of the hemostatic abnormalities associated with pathological overactivation of the hemostatic mechanism. Factors such as tissue thromboplastins and/or endotoxins can stimulate disseminated intravascular coagulation, particularly during pregnancy or in the early postpartum period when a physiological "hypercoagulable" state already exists. PMID:17422399

Johnstone, I B; Blackwell, T E

1984-05-01

393

Sulfation of tyrosine residues in coagulation factor V  

SciTech Connect

Sulfation of human coagulation factor V was investigated by biosynthetically labeling the products of HepG2 cells with ({sup 35}S)sulfate. There was abundant incorporation of the sulfate label into a product identified as factor V by immunoprecipitation, lability to proteases, affinity for the lectin jacalin, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two or more sites in factor V incorporated sulfate as indicated by labeling of different peptide chains of factor Va. The 150-Kd activation fragment of factor Va incorporated the greatest amounts of sulfate. This fragment of factor Va was bound selectively by jacalin-agarose, reflecting its content of O-linked oligosaccharides. Analysis of an alkaline hydrolysate of sulfate-labeled factor Va by anion-exchange chromatography showed that the sulfate occurred partly in tyrosine sulfate residues and partly in alkaline-labile linkages. Sulfate groups are potentially important structural and functional elements in factor V, and labeling with (35S)sulfate provides a useful approach for examining the biosynthesis and processing of this protein. The hypothesis is advanced that sites of sulfation in factor V and several other plasma proteins contribute to the affinity and specificity of thrombin for these molecules, just as it does for the interaction of thrombin with the potent inhibitor hirudin from leeches.

Hortin, G.L. (Washington Univ. School of Medicine, St Louis, MO (USA))

1990-09-01

394

Hepatocyte tissue factor activates the coagulation cascade in mice  

PubMed Central

In this study, we characterized tissue factor (TF) expression in mouse hepatocytes (HPCs) and evaluated its role in mouse models of HPC transplantation and acetaminophen (APAP) overdose. TF expression was significantly reduced in isolated HPCs and liver homogenates from TFflox/flox/albumin-Cre mice (HPC?TF mice) compared with TFflox/flox mice (control mice). Isolated mouse HPCs expressed low levels of TF that clotted factor VII-deficient human plasma. In addition, HPC TF initiated factor Xa generation without exogenous factor VIIa, and TF activity was increased dramatically after cell lysis. Treatment of HPCs with an inhibitory TF antibody or a cell-impermeable lysine-conjugating reagent prior to lysis substantially reduced TF activity, suggesting that TF was mainly present on the cell surface. Thrombin generation was dramatically reduced in APAP-treated HPC?TF mice compared with APAP-treated control mice. In addition, thrombin generation was dependent on donor HPC TF expression in a model of HPC transplantation. These results suggest that mouse HPCs constitutively express cell surface TF that mediates activation of coagulation during hepatocellular injury. PMID:23305736

Sullivan, Bradley P.; Kopec, Anna K.; Joshi, Nikita; Cline, Holly; Brown, Juliette A.; Bishop, Stephanie C.; Kassel, Karen M.; Rockwell, Cheryl; Mackman, Nigel

2013-01-01

395

Validation of a new whole blood coagulation monitoring system.  

PubMed

The Hemochron Response is a third generation point-of-care (POC) whole blood coagulation analyzer that retains the clinical utility of the Hemochron standard (801/8000) while providing a data management program that assists the POC coordinator with Quality Assurance (QA) compliance. Clinical and laboratory studies were performed to ensure consistency of the target anticoagulation times with the Hemochron standard and to evaluate precision and reproducibility of the Hemochron Response. Clinical tests for prothrombin time (PT) using fresh and citrated whole blood, activated clotting time (ACT), and activated partial thromboplastin time (APTT) showed excellent correlation to the Hemochron standard where r = 0.929, r = 0.969, r = 0.947, and r = 0.992, respectively. This was confirmed by a paired Student's t-test. The standard expectation for reproducibility of ACT tests has been a coefficient of variation (CV) of 10%. Laboratory studies of reproducibility and precision for the Response instrument included analysis of the CV using ACT test tubes. For normal and abnormal control plasma (CPL), the range of CVs observed was 3.3%-4.6% and 3.0%-5.0%, respectively. For heparin dose response analysis, the range for Donor 1 and 2 was 1.0%-4.2% and 1.1%-8.0%, respectively. These data suggest that the Hemochron Response is reliable and equivalent to the Hemochron standard in clinical applications. PMID:12533064

Jaryno, Stacy; Bennett, Kim; Loder, Carol; Zucker, Marcia L; Pan, Chi-Miau; LaDuca, Frank M

2002-12-01

396

Performance and characterization of a new tannin-based coagulant  

NASA Astrophysics Data System (ADS)

Diethanolamine and formaldehyde were employed to cationize tannins from black wattle. This novel coagulant called CDF was functionally characterized in removing sodium dodecylbenzene sulfonate (anionic surfactant) and Palatine Fast Black WAN (azoic dye). Refined tannin-derived commercial coagulants exhibited similar efficiency, while CDF presented higher coagulant ability than alum, a usual coagulant agent. Low doses of CDF (ca. 100 mg L-1) were able to remove more than 70 % of surfactant and more than 85 % of dye (initial pollutant concentration of ca. 100 mg L-1) and it presented no temperature affection and worked at a relatively wide pH range. Surfactant and dye removal responded to the classical coagulant-and-adsorption models, such as Frumkin-Fowler-Guggenheim or Gu and Zhu in the case of surfactant, and Langmuir and Freundlich in the case of dye.

Beltrán-Heredia, J.; Sánchez-Martín, J.; Gómez-Muñoz, C.

2012-09-01

397

Analysis of Coagulation Processes for the Groundwater Treatment  

NASA Astrophysics Data System (ADS)

Coagulation process is widely used for removal of natural organic matters (NOM) and for water color intensity reduction. The efficiency of coagulation process depends on many different factors. Aim of this research is to investigate coagulation process under different conditions. During the research coagulation process was held at different pH values (5.5; 6.0; 6.5), at different water alkalinity and at different water turbidity. It was found that removal of NOM and water color intensity reduction is most effective at pH values from 5.5 to 6.0. At these conditions water color intensity reduction is most efficient, but removal of dissolved organic carbon (DOC) is the lowest. During the research it was also found that different water alkalinity and turbidity do not make significant influence on efficiency of coagulation process.

Albrektiene, Ramune; Rimeika, Mindaugas; Jurkiene, Anzelika

2013-06-01

398

Interplay between coagulation and vascular inflammation in sickle cell disease  

PubMed Central

Sickle cell disease is the most common inherited hematologic disorder that leads to the irreversible damage of multiple organs. Although sickling of red blood cells and vaso-occlusion are central to the pathophysiology of sickle cell disease the importance of hemolytic anemia and vasculopathy has been recently recognized. Hypercoagulation state is another prominent feature of sickle cell disease and is mediated by activation of both intrinsic and extrinsic coagulation pathways. Growing evidence demonstrates that coagulation may not only contribute to the thrombotic complications, but also to vascular inflammation associated with this disease. This article summarizes the role of vascular inflammation and coagulation activation, discusses potential mechanisms responsible for activation of coagulation and reviews recent data demonstrating the crosstalk between coagulation and vascular inflammation in sickle cell disease. PMID:23593937

Sparkenbaugh, Erica; Pawlinski, Rafal

2013-01-01

399

The Role for Coagulation Markers in Mild Snakebite Envenomations  

PubMed Central

Introduction The majority of patients seeking medical treatment for snakebites do not suffer from severe envenomation. However, no guidelines exist for ordering coagulation markers in patients with minimal or moderate envenomation, nor in those who do not receive antivenom. In this study, we sought to determine whether it was possible to limit the practice of ordering coagulation studies to those patients suffering severe envenomation, rattlesnake envenomation, or both. Methods A retrospective chart review was performed on all cases of crotalid snakebite presenting to an adult emergency department (ED) from April 1998 to June 2006. Each chart was abstracted for patient's age, gender, type of snake (if known), severity of envenomation at initial presentation, coagulation test results, whether antivenom was administered, and whether the patient was admitted. Results Over an approximately 8-year period, 131 snakebite cases presented that met the inclusion criteria, of which 35 (26.7%) had some type of coagulation marker abnormality. Limiting coagulation testing to patients suffering severe envenomation or rattlesnake envenomation would have resulted in failure to identify 89% or 77%, respectively, of the 35 patients who were found to have at least 1 abnormal coagulation marker. Conclusion Our study failed to identify a subset of patients that could be defined as low risk or for whom coagulation marker testing could be foregone. This study suggests that coagulation tests should be routinely performed on all patients presenting to the ED with complaints of envenomation by copperheads, moccasins, or rattlesnakes. Further clarification of when coagulation markers are indicated may require a prospective study that standardizes snake identification and the timing of coagulation marker testing. PMID:22461925

Moriarity, Risa S; Dryer, Sylvia; Replogle, William; Summers, Richard L

2012-01-01

400

Experimental studies of O2\\/Ar plasma in a planar inductive discharge  

Microsoft Academic Search

A Langmuir probe was used to determine the electron density, electron temperature, plasma potential and the electron energy probability function (EEPF) in 0963-0252\\/8\\/1\\/003\\/img2 plasma in a planar inductive discharge for a pressure range of 2-30 mTorr. The electron density increases with increased argon content and increases more steeply with increased argon content after the fractional argon flowrate has reached 50%.

J. T. Gudmundsson; Takashi Kimura; M. A. Lieberman

1999-01-01

401

Intense terahertz emission from atomic cluster plasma produced by intense femtosecond laser pulses  

SciTech Connect

Terahertz (THz) emission from argon cluster plasma, generated by intense femtosecond laser pulses in the energy range of 10-70 mJ, has been investigated. THz polarization, energy dependence, and angular distribution were measured to provide an initial discussion on the mechanisms of THz emission. THz pulses of much higher energy were generated from argon clusters than from argon gas, which indicates that plasma produced from atomic clusters holds considerable promise as an intense THz source.

Jahangiri, Fazel; Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan and Department of Physics, GSS, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-7501 (Japan); Nagashima, Takeshi; Hangyo, Masanori [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2011-12-26

402

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

E-print Network

; Backwashing (water treatment); Pollution; Fuels; Drilling. Introduction The removal of oil from water, in the case that the water source is an ocean, it may affect the ecology of the ocean floor. By the combinedCoagulation of Oil in Water Using Sawdust and Bentonite and the Formation of a Floating Coagulated

Chung, Deborah D.L.

403

Contact Activation of Blood Plasma and Factor XII by Ion-exchange Resins  

PubMed Central

Sepharose ion-exchange particles bearing strong Lewis acid/base functional groups (sulfopropyl, carboxymethyl, quarternary ammonium, dimethyl aminoethyl, and iminodiacetic acid) exhibiting high plasma protein adsorbent capacities are shown to be more efficient activators of blood factor XII in neat-buffer solution than either hydrophilic clean-glass particles or hydrophobic octyl sepharose particles ( FXII?surfaceactivatorFXIIa; a.k.a autoactivation, where FXII is the zymogen and FXIIa is a procoagulant protease). In sharp contrast to the clean-glass standard of comparison, ion-exchange activators are shown to be inefficient activators of blood plasma coagulation. These contrasting activation properties are proposed to be due to the moderating effect of plasma-protein adsorption on plasma coagulation. Efficient adsorption of blood plasma proteins unrelated to the coagulation cascade impedes FXII contacts with ion-exchange particles immersed in plasma, reducing autoactivation, and causing sluggish plasma coagulation. By contrast, plasma proteins do not adsorb to hydrophilic clean glass and efficient autoactivation leads directly to efficient activation of plasma coagulation. It is also shown that competitive-protein adsorption can displace FXIIa adsorbed to the surface of ion-exchange resins. As a consequence of highly-efficient autoactivation and FXIIa displacement by plasma proteins, ion-exchange particles are slightly more efficient activators of plasma coagulation than hydrophobic octyl sepharose particles that do not bear strong Lewis acid/base surface functionalities but to which plasma proteins adsorb efficiently. Plasma proteins thus play a dual role in moderating contact activation of the plasma coagulation cascade. The principal role is impeding FXII contact with activating surfaces but this same effect can displace FXIIa from an activating surface into solution where the protease can potentiate subsequent steps of the plasma coagulation cascade. PMID:21982294

Yeh, Chyi-Huey Josh; Dimachkie, Ziad O.; Golas, Avantika; Cheng, Alice; Parhi, Purnendu; Vogler, Erwin A.

2011-01-01

404

Determination of low-molecular-weight heparin by Heptest on the automated coagulation laboratory system.  

PubMed

The manual Heptest for measuring low-molecular-weight heparin fractions was applied to a fully automated, coagulation-dedicated analyzer, the Automated Coagulation Laboratory 300 Plus. The clot-based assay mode of the instrument was used, which operates on the principle of light scattering. Undiluted plasmas and the original reagents of the Heptest kit were used. Also, the 2-minute incubation time of the manual procedure was maintained. Automation reduced plasma and reagent volumes by about one half. As a result of the high precision of the automated procedure, single determinations suffice, and 18 plasma samples can be analyzed in about 8 minutes. Coefficients of variation were 1.0% to 3.2% for within-run and 1.9% to 6.0% for inter-run analyses. Analytical recovery was 98% to 104%. Comparisons of 132 samples between the two procedures yielded an R value of 0.974 for activity expression in seconds and 0.945 for U/mL. Several low-molecular-weight heparin fractions were tested. PMID:8438788

Ozawa, T; Domagalski, J; Mammen, E F

1993-02-01

405

Platelet aggregation, secretion, and coagulation changes in children with asthma.  

PubMed

The chronic inflammation in asthma evolves by cells including eosinophils, mast cells and lymphocytes. Despite their principal function in hemostasis, platelets contribute to pathogenesis of asthma that activation of platelets occurs following antigen provocation and during asthma attack. Our aim was to evaluate the platelet functions and other hemostatic features of children with asthma, both during symptom-free period and asthma attack. We enrolled patients with asthma attack (n?=?33), mild intermittent asthma (n?=?18), mild persistent asthma (n?=?15) and healthy children (n?=?20). Demographic characteristics and disease-related features were noted. Platelet aggregation and secretion tests (expressed as ATP release) were performed by lumiaggregometer method by stimulation with collagen, epinephrine, ADP, thrombin, ristocetin and arachidonic acid. Plasma levels of D-dimer, factor VIII (FVIII) and von Willebrand factor (vWF) were assessed. There were no differences in platelet aggregation induced by agonists between study groups. ATP release from platelets of patients with asthma exacerbation induced by ADP was lower compared with mild intermittent asthma (P?plasma levels of vWF and FVIII provide evidence that coagulation mechanisms might be critical for asthma pathogenesis. PMID:24842314

Buyukyilmaz, Gonul; Soyer, Ozge U; Buyuktiryaki, Betul; Alioglu, Bulent; Dallar, Yildiz

2014-10-01

406

Investigations of Bacterial Inactivation and DNA Fragmentation Induced by Flowing Humid Argon Post-discharge  

NASA Astrophysics Data System (ADS)

Bio-contaminated surfaces were exposed to an atmospheric pressure flowing post-discharge, i.e. without direct contact of the plasma with the surface. The non-thermal plasma source was a dielectric barrier discharge. Using humid argon as a feed gas, a reduction of six orders of magnitude of survivors could be obtained for Escherichia coli. An investigation of bacterial inactivation mechanisms during the plasma induced treatment was conducted. For this purpose, DNA (plasmid and genomic DNA in aqueous solution) degradation by the plasma process was studied, assuming that the bacterial inactivation is obtained when the bacterial DNA is fragmented. According to the operating conditions (feed gas, reactor geometry and discharge input power), DNA fragmentation was evaluated in correlation with aqueous phase hydrogen peroxide concentration measurements. It appears that hydrogen peroxide is not the only factor responsible for DNA fragmentation and that short-lived species produced by water dissociation are major contributors.

Odic, Emmanuel; Limam, S.; Kirkpatrick, M. J.; Dodet, B.; Salamitou, S.; DuBow, M. S.

407

Coagulation in the sand crab (Ovalipes bipustulatus).  

PubMed

The coagulation mechanism of the sand crab (O. bipustulatus) has been investigated. From the coagulocytes (amoebocytes) present in the crab haemolymph (blood), fibrinogen (coagulogen) was isolated. It was shown to be homogeneous by electrophoresis on S.D.S. polyacrylamide gel and had a molecular weight similar to the A alpha-chain of human fibrinogen. Unlike human fibrinogen. Unlike human fibrinogen it cannot be dissociated by reduction. In fibrin polymerization, a crosslinking process takes place and this process was inhibited by glycine ethyl ester. A fibrin stabilizing factor is present in the crab haemolymph and this protein was able to cross-link human fibrin in the same manner as human factor XIII. PMID:505375

Madaras, F; Parkin, J D; Castaldi, P A

1979-08-31

408

Long-Term Expression of Human Coagulation Factor VIII and Correction of Hemophilia A after in vivo Retroviral Gene Transfer in Factor VIII-Deficient Mice  

Microsoft Academic Search

Hemophilia A is caused by a deficiency in coagulation factor VIII (FVIII) and predisposes to spontaneous bleeding that can be life-threatening or lead to chronic disabilities. It is well suited for gene therapy because a moderate increase in plasma FVIII concentration has therapeutic effects. Improved retroviral vectors expressing high levels of human FVIII were pseudotyped with the vesicular stomatitis virus

Thierry Vandendriessche; Veerle Vanslembrouck; Inge Goovaerts; Hans Zwinnen; Marie-Line Vanderhaeghen; Desire Collen; Marinee K. L. Chuah

1999-01-01

409

ccsd00003163, High Resolution Helike Argon And Sulfur Spectra From  

E-print Network

ccsd­00003163, version 1 ­ 26 Oct 2004 High Resolution He­like Argon And Sulfur Spectra From of Aveiro, Portugal Abstract. We present new results on the X­ray spectroscopy of multicharged argon, sulfur of multicharged F­like to He­like argon, sulfur and chlorine with one 1s hole. In particular, we observed the 1s2s

410

Laser spectroscopy of thermal plasma  

NASA Astrophysics Data System (ADS)

Thermal plasma, due to its applications, is a research field of great importance, but reliable diagnostics of such plasma remains a challenging task. Spatially resolved methods, which provide local values of plasma parameters, are crucial for understanding the underlying physics. This can be achieved using pump-probe techniques. Two methods applicable and useful for thermal plasma diagnostics—four-wave mixing and scattering of laser beams—are discussed in this paper. Experimental examples of their application, namely four-wave mixing in argon arc plasma and scattering of laser light by laser-induced plasma, are presented.

Pokrzywka, Bart?omiej; Dzier??ga, Krzysztof; Mendys, Agata; Pellerin, Stephane

2014-05-01

411

Bumping phenomenon during continuous coagulation with bipolar forceps.  

PubMed

During continuous bipolar coagulation, the coagulum sometimes ruptures suddenly and audibly, leading to hemostasis failure and damage to the surrounding tissues. Such coagulum rupture is a phenomenon that is similar to microwave bumping, which occurs because of unequal heat distribution as a result of sudden elevation in temperature. The present study investigated the conditions under which bumping can occur during bipolar coagulation using samples of whole blood. Two types of bipolar forceps were assessed: forceps with gold-plated tips and IsoCoolTM forceps. The time until the bumping phenomenon occurred was measured, and the occurrence rate of bumping was calculated. Thermal characteristics were then assayed using a thermographic camera. As the output of the bipolar coagulator increased, the time until bumping decreased whereas the occurrence rate of bumping during coagulation increased. At lower outputs, the occurrence rate of bumping was significantly lower using IsoCoolTM forceps than that using forceps with gold-plated tips (p<0.0001). Furthermore, bumping during coagulation could be prevented if the tips of the forceps at the coagulation site were repeatedly opened and closed. The bumping phenomenon is influenced by various factors such as heat, electrical power, equipment, and coagulation technique. Neurosurgeons should understand the technical certain aspects of these surgical tools and develop appropriate advanced techniques for temperature control. PMID:23095265

Mikami, Takeshi; Wanibuchi, Masahiko; Mikuni, Nobuhiro

2012-01-01

412

Controlling and characterizing the coagulation of liquid aerosol droplets.  

PubMed

We demonstrate that optical tweezers can be used to control and characterize the coagulation and mixing state of aerosols. Liquid aerosol droplets of 2-14 mum in diameter are optically trapped and characterized by spontaneous and stimulated Raman scatterings, which together provide a unique signature of droplet size and composition. From the conventional bright field image, the size of the trapped droplet can be estimated and compared with that determined from stimulated Raman scattering, and the motion of the particle within the trapping plane can be recorded. A maximum of four droplets can be manipulated in tandem by forming multiple optical traps through rapid beam steering. The coagulation of two droplets can be studied directly by controlling two droplets. The limiting conditions under which optical forces and capillary forces dominate the aerosol coagulation event are explored by varying the relative optical trap strengths and characterizing the coagulation of different droplet sizes. Finally, we demonstrate that the coagulation of different aerosol components can be compared and the mixing state of the final coagulated droplet can be investigated. In particular, we compare the outcome of the coagulation of an aqueous sodium chloride aerosol droplet with a second aqueous droplet, with an ethanol droplet or with a decane droplet. PMID:16999489

Buajarern, Jariya; Mitchem, Laura; Ward, Andrew D; Nahler, N Hendrik; McGloin, David; Reid, Jonathan P

2006-09-21

413

Atomistic Simulation of Shock Wave-Induced Melting in Argon  

PubMed

A three-dimensional molecular dynamics simulation of shock wave loading was undertaken to investigate the Hugoniot equation of state at the transition of argon from solid to liquid. The simulated data agree with shock wave and static high-pressure experimental data. The melting transition in this simulation occurs without overshooting the argon melting temperature. There are two discontinuities that may bracket a mixed-phase region of solid and liquid along the simulated argon Hugoniot. This is an intrinsic feature of the Hugoniot crossing the argon melting curve and does not require the addition of any solid-solid phase transition. PMID:9020073

Belonoshko

1997-02-14

414

Carbon monoxide releasing molecule-2 enhances coagulation and attenuates fibrinolysis by two mechanisms: insights gained with colloid dilution.  

PubMed

Carbon monoxide releasing molecule-2 (CORM-2, tricarbonyldichlororuthenium (II) dimer) enhances coagulation and attenuates vulnerability to fibrinolysis. Our goal was to further define the CORM-2-mediated mechanisms using colloids with known effects on coagulation/fibrinolytic proteins. Plasma diluted 0 or 30% with 0.9% NaCl, 5% human albumin, low molecular weight hydroxyethyl starch (130 kDa) or high molecular weight hydroxyethyl starch (450 kDa) was exposed to 0 or 100 ?mol/l CORM-2 before activation with tissue factor (n = 8 per condition). A second identically diluted series of experiments were performed with the addition of tissue-type plasminogen activator. Thrombelastographic data were collected until clot strength stabilized or clot lysis occurred. Dilution resulted in fluid-specific decreases in velocity of clot growth, strength and clot growth time with progressive increases in macromolecule size. CORM-2 exposure significantly increased the velocity of clot formation and strength (thin fibrin fiber promoting), but not clot growth time, under all conditions. Fibrinolysis was enhanced to the greatest extent by hydroxyethyl starch (anti?2-antiplasmin effect), and CORM-2 addition attenuated fibrinolysis in all conditions (?2-antiplasmin enhancement). CORM-2 exposure attenuated the decrease in coagulation kinetics mediated by hemodilution by two different mechanisms based on kinetic profile differences between the diluents tested. Further laboratory-based investigation is warranted to further define the molecular mechanisms responsible for CORM-2-mediated effects on coagulation and fibrinolysis. PMID:21157300

Cohen, Jack B; Persaud, Joshua M; Malayaman, Saninuj N; Nielsen, Vance G

2011-01-01

415

Changes in the human blood coagulating system during prolonged hypokinesia  

NASA Technical Reports Server (NTRS)

Changes in the coagulating system of the blood were studied in six subjects during prolonged hypokinesia. Thrombogenic properties of the blood rose in all cases on the 8th day. These changes are explained by stress reaction due to unusual conditions for a healthy person. Changes in the blood coagulating system in the group subjected to physical exercise and without it ran a practically parallel course. Apparently physical exercise is insufficient to prevent such changes that appear in the coagulating system of the blood during prolonged hypokinesia.

Filatova, L. M.; Anashkin, O. D.

1978-01-01

416

Characterization of argon direct-current glow discharge with a longitudinal electric field applied at ambient air  

NASA Astrophysics Data System (ADS)

A direct-current-driven plasma jet is developed by applying a longitudinal electric field on the flowing argon at ambient air. This plasma shows a torch shape with its cross-section increased from the anode to the cathode. Comparison with its counterparts indicates that the gas flow plays a key role in variation of the plasma structure and contributes much to enlarging the plasma volume. It is also found that the circular hollow metal base promotes generation of plasma with a high-power volume density in a limited space. The optical emission spectroscopy (OES) diagnosis indicates that the plasma comprises many reactive species, such as OH, O, excited N2, and Ar metastables. Examination of the rotational and vibrational temperature indicates that the plasma is under nonequilibrium condition and the excited species OH(A 2?+), O(5P), and N2(C 3?u) are partly generated by energy transfer from argon metastables. The spatially resolved OES of plasma reveals that the negative glow, Faraday dark space, and positive column are distributed across the gas gap. The absence of the anode glow is attributed to the fact that many electrons in the vicinity of the anode follow ions into the positive column due to the ambipolar diffusion in the flowing gas.

Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang

2014-09-01

417

Optimization of coagulation with PFS-PDADMAC composite coagulants using the response surface methodology experimental design technique.  

PubMed

In this study, two composite coagulants, PFPD1, and PFPD2, were prepared and studied with the inorganic polymer coagulant PFS. A response surface design was used to investigate the effect that changes in the level of coagulant dose and coagulation pH have on residual turbidity and TOC. In addition, the optimum combinations of dose and pH, that yield the lowest residual turbidity and TOC, were determined. The results revealed that the optimum conditions for the three coagulants were a dosage of 204 mg/L and pH of 8.06 for PFS; a dosage of 179 mg/L and pH of 7.99 for PFPD1; and a dosage of 112 mg/L and pH of 7.65 for PFPD2. The models showed that for residual turbidity, the effectiveness of the coagulants in decreasing order was PFS>PFPD1 > PFPD2, while for residual TOC, the order was PFPD2 > PFPD1 > PFS. The verification experiments demonstrated that a RSM approach was appropriate for optimizing the coagulation-flocculation process. PMID:23789575

Tshukudu, Tiroyaone; Zheng, Huaili; Yang, Jun

2013-05-01

418

INSTITUTE OF PHYSICS PUBLISHING PLASMA SOURCES SCIENCE AND TECHNOLOGY Plasma Sources Sci. Technol. 16 (2007) 9096 doi:10.1088/0963-0252/16/1/012  

E-print Network

INSTITUTE OF PHYSICS PUBLISHING PLASMA SOURCES SCIENCE AND TECHNOLOGY Plasma Sources Sci. Technol from a pulsed plasma through a grid Sang Ki Nam, Demetre J Economou and Vincent M Donnelly Plasma was developed to study ion extraction from a capacitively-coupled argon plasma through a grid. A one

Economou, Demetre J.

419

Impacts of Substituting Aluminum-Based Coagulants in Drinking Water Treatment  

Microsoft Academic Search

Aluminum-based coagulants in drinking water treatment are widely used across Canada. According to the literature, the presence of aluminum in drinking water poses possible risks to humans. Preliminary studies investigating the use of alterna- tive coagulating agents such as iron-based coagulants, lanthanide salts and organic coagulants have already revealed that their implementation is possible, but require further studies concerning their

Patrick Niquette; Frédéric Monette; Abdelkrim Azzouz; Robert Hausler

2004-01-01

420

Application of coagulants in pretreatment of fish wastewater using factorial design  

Microsoft Academic Search

The effect of aluminum sulfate and ferric chloride on the coagulation of the effluent from the fish industry was investigated. Jar test experiments were used to evaluate the effect of parameters such as pH, type of coagulation and coagulant dose. A complete 3×2 factorial design was used where the independent variables were: type of coagulant (aluminum sulfate and ferric chloride),

A. G. M. Silva; M. O. Hornes; M. L. Mitterer; M. I. Queiroz

2009-01-01