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Sample records for argon laser photocoagulation

  1. Binocular indirect argon laser photocoagulator.

    OpenAIRE

    Mizuno, K

    1981-01-01

    The binocular indirect argon laser photocoagulator was newly designed to enable visualisation of the entire fundus during panretinal laser photocoagulation and to treat retinal tears immediately after buckling procedures of the sclera. The lamp housing of the binocular ophthalmoscope was remodelled and adjusted so that the laser beam and illuminating light are coaxial after leaving the ophthalmoscope. The blocking filter was permanently fixed in the eye-pieces to lighten the weight of the oph...

  2. Laser photocoagulation - eye

    Science.gov (United States)

    Laser coagulation; Laser eye surgery; Photocoagulation; Laser photocoagulation - diabetic eye disease; Laser photocoagulation - diabetic retinopathy; Focal photocoagulation; Scatter (or pan retinal) photocoagulation; Proliferative ...

  3. Effect of Ginkgo biloba on the lesions induced by retinal argon laser photocoagulation in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Clairambault, P.; Pairault, C.; Droy-Lefaix, M.T.; Magnier, B.; Magnier, M.

    1986-01-09

    In rabbits, retinal argon laser photocoagulation disrupts the arrangement of cell layers and produces interstitial edema. Photochemical and thermal energy is released with production of free oxygenated radicals that are responsible for destruction of cell membranes. Retinal argon laser photocoagulation in rabbits was used as a pharmacologic model to evaluate the protective effect of EGB 761 against membrane lesions and edema. As a strong free radicals scavengers, EGB 761 confirms its protective action on cells membranes and its anti-edema effect.

  4. Effect of Ginkgo biloba on the lesions induced by retinal argon laser photocoagulation in rabbits

    International Nuclear Information System (INIS)

    In rabbits, retinal argon laser photocoagulation disrupts the arrangement of cell layers and produces interstitial edema. Photochemical and thermal energy is released with production of free oxygenated radicals that are responsible for destruction of cell membranes. Retinal argon laser photocoagulation in rabbits was used as a pharmacologic model to evaluate the protective effect of EGB 761 against membrane lesions and edema. As a strong free radicals scavengers, EGB 761 confirms its protective action on cells membranes and its anti-edema effect

  5. 倒睫激光疗效106例观察%Treatment of trichiasis with argon laser photocoagulation

    Institute of Scientific and Technical Information of China (English)

    徐冬冬; 于伟鸿; 董方田

    2010-01-01

    Objective To observe the clinical effect with the use of Argon laser photocoagulation for the treatment of recurrent trichiasis patients. Methods A total of 106 lids (73 patients) with aberrant lashes were treated in our study. Each lash was treated with a beam of 50-200μm (spot size), 0.2s (time), and 500-1000mW .power). Topical or infiltration anesthesia was used. The beam was focused at the root of the aberrant cilium and a 2-3mm crater was produced at its base. This was then deepened to destroy the whole lash follicle. At the conclusion of the laser treatment, the patient was discharged on topical antibiotic eye drops three times a day for one week. Results Successful treatment with no evidence of recurrence was achieved in 64.2% of lids after one laser session. Of 101 lids (95.3%) achieved no recurrence with three sessions laser treatment. With one laser session, the success rate was 78.9% when aberrant lashes per lid were below 5 and 33.3%when aberrant lashes were from 5-10. If the aberrant lashes per lid were above 10, several sessions of laser was needed. With one laser session, the success rate of trachoma was 41.7%, 72.4% for blepharitis and 81.8% for idiopathic trichiasis. Conclusions Argon laser treatment appears to be a safe and effective method to the treatment of trichiasis. The success rate is lower when the aberrant lashes per lid are more. Among the different causes of trichiasis, trachoma carries a significant low success rate.%目的 对氩激光光凝后的倒睫患者进行随诊,观察这种方法的临床效果.方法 应用氩激光治疗倒睫毛,将能量设为500~1000m W,时间为200m s,光斑50~200μm,使激光束对准倒睫毛的根部,产生2~3m m直径的小凹陷,继续激光破坏毛囊.激光后应用抗生素滴眼液一周.结果 73位患者106只眼接受了氩激光治疗.每根倒睫所需激光点数(53.7±19.1)点,68只眼经1次激光治愈,成功率64.2%,经3次激光,101只眼(95.3%)达到治愈效果.眼睑≤5

  6. Laser photocoagulation for retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    K. A. Mirzabekova

    2015-03-01

    Full Text Available Retinal vein occlusion (RVO is one of the leading causes of permanent vision loss. In adults, central retinal vein occlusion (CRVO occurs in 1.8% while branch retinal vein occlusion (BRVO occurs in 0.2%. Treatment strategy and disease prognosis are determined by RVO type (ischemic/non-ischemic. Despite numerous studies and many current CRVO and BRVO treatment approaches, the management of these patients is still being debated. Intravitreal injections of steroids (triamcinolone acetate, dexamethasone and vascular endothelial growth factor (VEGF inhibitors (bevacizumab, ranibizumab were shown to be fairly effective. However, it is unclear whether anti-VEGF agents are reasonable in ischemic RVOs. Laser photocoagulation remains the only effective treatment of optic nerve head and/or retinal neovascularization. Laser photocoagulation is also indicated for the treatment of macular edema. Both threshold and sub-threshold photocoagulation may be performed. Photocoagulation performed with argon (514 nm, krypton (647 nm, or diode (810 nm laser for macular edema provides similar results (no significant differences. The treatment may be complex and include medication therapy and/or surgery. Medication therapy includes anti-aggregant agents and antioxidants, i.e., emoxypine which may be used in acute RVO as well as in post-thrombotic retinopathy. 

  7. Comparison of Diode and Argon Laser Lesions in Rabbit Retina

    Institute of Scientific and Technical Information of China (English)

    Hui Zhang; Xiaoxin Li; Bin Li; Jiping Da

    2004-01-01

    Purpose: To compare the histological alteration of retina with various spot intensities between diode and argon lasers in order to instruct the clinical use of 810 nm diode laser.Methods: Transpupillary retinal photocoagulations were performed on 42 eyes of 27pigmented rabbits. Histopathologic alteration of lesions in different intensities and different time intervals after irradiation produced by diode and argon laser was observed and compared using light microscopy. Areas of various lesions measured by image analysis system (CMIAS) were compared quantitatively.Results: Histopathologically, two-week-old grade 2 lesions produced by diode laser induced the disappearance of outer nuclear cells. More than a half of all showed reduction in number of outer nuclear layer cells in argon. Fibroblasts appeared in the diode grade 3lesions 5 days after irradiation. CMIAS data showed that all the areas of diode lesions immediately after photocoagulation were to be larger than those of argon laser lesions in the same spot intensity (P < 0.05). However, twenty-four hours after photocoagulation, the area of the diode lesions increased less than that of the argon laser lesions (8%vs.23%).Conclusion: The acute histological effect caused by 810 nm diode laser and argon green laser is similar,while the expansion of lesion area 24 hours after photocoagulation was less with the diode laser compared to the argon. This may be the first report in the literature regarding quantitative analysis of the delayed reaction of argon green lasers.

  8. Argon laser photocoagulation for 24 eyes of recurrent trichiasis%Argon激光治疗复发性倒睫24眼

    Institute of Scientific and Technical Information of China (English)

    朱承华; 卞春及

    2004-01-01

    AIM: To evaluate the efficacy and safety of Argon laser microsurgery for the treatment of recurrent trichiasis.METHODS: A total of 24 eyes (18 patients) with aberrant lashes were treated. Each lash was treated with a beam of 50-200 μ m (spot size), 0.25-0.5s (time), and 400-800mW(power). Some ingrowing lashes were dyed in methylene blue before the treatment. No anaesthetic was used for the procedure. The mean follow-up time was 6.12 months.RESULTS: Successful treatment with no evidence ofrecurrence was achieved in 83.3% eyes after one to four laser sessions. Irritating symptoms of all patients disappeared or were obviously relieved after treatment.There was a significant correlation between the number of aberrant lashes per eye and the number of required laser sessions. Complete healing of the treated area occurred within six weeks after the procedure, with no vascularization or distortion of the lid margin.CONCLUSION: Argon laser treatment appears to be a quick, simple and convenient, safe and effective alternarive to the other recognized methods in selected cases.%目的:评价氩激光治疗复发性倒睫的疗效和安全性.方法:Argon激光治疗18例(24眼)复发性倒睫,光斑50~200 u m,时间0.25~0.5s,能量400~800mW.部分倒睫用美蓝染色后治疗.治疗全过程无需麻醉,平均随访时间6.12mo.结果:经过1~4次氩激光治疗,其中83.33%痊愈.刺激症状消失或明显减轻.激光治疗次数与倒睫数量间明显相关.治疗6wk后所有患者无睑缘畸形和新生血管形成.结论:氩激光治疗复发性倒睫较其他治疗方法安全、有效、简便、副作用小.

  9. Long-term outcome following interstitial laser photocoagulation of benign cold thyroid nodules

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbæk, Finn Noe; Hegedüs, Laszlo

    2011-01-01

    To evaluate the long-term efficacy of interstitial laser photocoagulation (ILP) in solitary benign thyroid nodules.......To evaluate the long-term efficacy of interstitial laser photocoagulation (ILP) in solitary benign thyroid nodules....

  10. Percutaneous laser photocoagulation of osteoid osteomas under CT guidance

    Energy Technology Data Exchange (ETDEWEB)

    Friend, D.E. de; Smith, S.P.; Hughes, P.M

    2003-03-01

    AIM: The aim was to evaluate laser photocoagulation and the use of the Bonopty needle system in the treatment of osteoid osteoma. MATERIALS AND METHODS: Five patients with osteoid osteomas were treated with computed tomography (CT)-guided, percutaneous laser photocoagulation using the Bonopty biopsy system. RESULTS: Complete pain relief was obtained in four patients. In one patient, pain persisted until the 6 weeks follow-up but resolved within 24 h of repeating the procedure. There were no complications, and patients remained symptom free at follow-up of 4-23 months (mean, 14 months). CONCLUSION: CT-guided laser photocoagulation of osteoid osteoma is a minimally invasive technique that represents a cost-effective alternative to surgical excision. The Bonopty needle system allows successful penetration of the sclerotic bone surrounding the nidus with manual pressure alone.

  11. Efficacy of Pattern Scan Laser photocoagulation for superficial conjunctival nevi ablation.

    Science.gov (United States)

    Park, Young Min; Lee, Ji-Eun; Lee, Jong Soo

    2016-07-01

    This study reports the efficacy and safety of Pattern Scan Laser (PASCAL) photocoagulation in the removal of superficial conjunctival nevi. Superficial conjunctival nevi were removed from 10 eyes of 10 patients using PASCAL. The laser spots were 200 μm in size, and the power delivered ranged from 250 to 300 mW. The duration of the laser pulse was kept at the minimum needed for adequate lesion removal. The duration of the laser pulse administered to the patients varied from 100 to 200 ms. Complete removal of the conjunctival nevus was observed in all the patients after PASCAL photocoagulation. Six months after treatment, complete re-epithelialization of the overlying conjunctiva was noted. No signs of recurrence or scarring were found in any of the patients during the follow-up period. Pure thermal denaturation is the main mechanism of PASCAL photocoagulation for removal of superficial conjunctival nevi. PASCAL can be considered as an alternative to conventional argon laser treatment or surgery. PMID:26914686

  12. LASER PHOTOCOAGULATION IN DIABETIC MACULAR EDEMA: EFFECTS ON VISUAL ACUITY AND MACULAR EDEMA

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    M.H. Dehghan

    1999-06-01

    Full Text Available Due to the importance of clinically significant macular edema in diabetic patients, this study is aimed to determine if laser photocoagulation is effective in the treatment of clinically significant diabetic macular edema. In addition, the effects of risk factors arc surveyed* This is an existing data study considering patients with clinically significant diabetic macular edema, treated with argon-green laser photocoagulation in Labbafinejad hospital, department of lasertherapy, from 1995 to 1997. in 60 (42.6% eyes the treatment method was focal, in 22 (15.6% eyes grid, and in 59 (41.84 modified grid laser photocoagulation was performed. The results are based upon deterioration of visual acuity, occurance of moderate visual loss and improvement or persistence of CSME. We studied 114 eyes from 87 patients. Two years after initial treatment, visual acuity improved in 19.1% of eyes, unchanged in 9.5% and worsened in 71.4% of eyes. After this period the rate of moderate visual loss was 28.6% and CSME was improved in 23.8% of eyes. According to our study, baseline visual acuity and retinopathy severity were two important intervening factors in response to lasertherapy. Comparing our results with natural course of diabetic macular edema, indicates that in assessing visual outcome laser photocoagulation is an effective modality in treatment of CSME, but it is not effective in maintaining or improving visual acuity, which is due to patients delay in visiting ophthalmologists and paying not enough attention to follow-up visits.

  13. Reversal of TTTS after fetoscopic laser photocoagulation for communicating vessels

    OpenAIRE

    Miyazaki, Masahide; Honda, Naotoshi; Yokoyama, Motofumi; Nakata, Masahiko

    2014-01-01

    We report a case of reversal of twin-to-twin transfusion syndrome (Stage IV TTTS) at 24  weeks of gestation after fetoscopic laser photocoagulation (FLP) for communicating vessels. The pathology of reversal of TTTS found that the ‘initial’ donor developed polyhydramnios whereas the ‘initial’ recipient developed oligohydramnios. With careful follow-up, the hydrops fetalis of the ‘initial’ recipient improved at 31 weeks of gestation. Because of the onset of labour pain at 34  weeks of gestation...

  14. Serous retinal detachment following panretinal photocoagulation (PRP) using Pattern Scan Laser (PASCAL) photocoagulator

    Science.gov (United States)

    Azar, Georges; Wolff, Benjamin; Cornut, Pierre-Loïc; Mauget-Faÿsse, Martine

    2012-01-01

    Objective: To report a case of serous retinal detachment after Pattern Scan Laser (PASCAL) treatment in a diabetic woman. Methods: A 34-year-old diabetic woman presented with florid diabetic retinopathy after a miscarriage during the 20th week of pregnancy. Her Best Corrected Visual Acuity (BCVA) was 20/40 right eye (OD) and 20/30 left eye (OS). Fundus exam showed multiple microaneurysms, large blot hemorrhages and venous dilation both eyes (OU). Fundus fluorescein angiography (FFA) revealed large areas of capillary nonperfusion and panretinal neovascularisation in all quadrants OU. Macular Spectral-Domain Optical Coherence Tomography scan (SD-OCT) did not show any foveal thickening. Panretinal photocoagulation (PRP) was immediately performed OU during the same day. Results: Two days after PASCAL treatment, her BCVA decreased to 20/80 OU and worsened to Count Fingers (CF) during the following days. Fundus exam revealed an extensive serous retinal detachment confirmed on SD-OCT. 2 sub-conjunctival injections of 0.1 ml Betamethasone were done OU. One month later, BCVA improved to 20/30 and SD-OCT confirmed regression of retinal detachment. Conclusions: PASCAL is considered to be a safe treatment, but one has to be aware of its potential side effects. It has to be used with caution in pregnant women.

  15. Posterior Pole Sparing Laser Photocoagulation Combined with Intravitreal Bevacizumab Injection in Posterior Retinopathy of Prematurity

    OpenAIRE

    2014-01-01

    Purpose. To report the results of the posterior pole sparing laser photocoagulation combined with intravitreal bevacizumab injection (IVB) in retinopathy of prematurity (ROP). Methods. A retrospective chart review of premature babies with ROP, all of whom received laser photocoagulation with IVB. Eleven eyes of 6 infants with advanced zone I ROP underwent laser ablation sparing posterior pole with concurrent IVB. The results were compared with those of full-laser treatment combined with IVB t...

  16. Congenital retinoschisis : successful collapse with photocoagulation.

    OpenAIRE

    Gopal L; Shanmugam M; Battu R; Shetty N

    2001-01-01

    We report a case of progressive congenital retinoschis is where the schisis cavity collapsed following argon laser photocoagulation. Despite reports to the contrary, we feel that in the absence of significant vitreous or inner layer traction, photocoagulation applied as light burns in the schisis cavity may be beneficial in collapsing the cavity. Whether or not this collapse of the schisis cavity reduces the risk of rhegmatogenous retinal detachment is unclear.

  17. Congenital retinoschisis : successful collapse with photocoagulation.

    Directory of Open Access Journals (Sweden)

    Gopal L

    2001-01-01

    Full Text Available We report a case of progressive congenital retinoschis is where the schisis cavity collapsed following argon laser photocoagulation. Despite reports to the contrary, we feel that in the absence of significant vitreous or inner layer traction, photocoagulation applied as light burns in the schisis cavity may be beneficial in collapsing the cavity. Whether or not this collapse of the schisis cavity reduces the risk of rhegmatogenous retinal detachment is unclear.

  18. Interstitial laser photocoagulation (ILP) of benign cystic thyroid nodules--a prospective randomized trial

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbæk, Finn Noe; Hegedüs, Laszlo

    2013-01-01

    Recurrence rate, after aspiration, in cystic thyroid nodules is very high. Interstitial laser photocoagulation (ILP) is a minimally invasive procedure that reduces the need for surgery in patients with a benign solid thyroid nodule.......Recurrence rate, after aspiration, in cystic thyroid nodules is very high. Interstitial laser photocoagulation (ILP) is a minimally invasive procedure that reduces the need for surgery in patients with a benign solid thyroid nodule....

  19. Effect of focal laser photocoagulation in eyes with mild to moderate non-proliferative diabetic retinopathy

    Science.gov (United States)

    Jeong, Seong Hun; Han, Jung Il; Cho, Sung Won; Lee, Dong Won; Kim, Chul Gu; Lee, Tae Gon; Kim, Jong Woo

    2016-01-01

    AIM To report the effect of focal laser photocoagulation on both the severity of hard exudates (HEs) and the rate of disease progression in eyes with mild to moderate non-proliferative diabetic retinopathy (NPDR). METHODS We retrospectively reviewed the medical records of 33 patients (60 eyes) who had been diagnosed with mild to moderate NPDR between January 2006 and December 2012. The patients were divided into 2 groups: Group A (38 eyes in 20 patients treated using focal laser photocoagulation) and Group B (treated without laser photocoagulation). We also reviewed the best corrected visual acuity measurements, and the fundus photographs taken at both baseline and follow-up visits. RESULTS In Group A, HE severity grade had decreased significantly from baseline to the final visit (Plaser photocoagulation reduced the levels of HEs in eyes with mild to moderate NPDR. However, the treatment was not able to decelerate the progression of DR.

  20. Percutaneous laser photocoagulation of osteoid osteoma: Assessment of treatment in nine cases

    International Nuclear Information System (INIS)

    Background: Osteoid osteoma is a benign bony neoplasm and its classic treatment is surgery. In the recent decades percutaneous laser therapy was suggested to be replaced by surgery. In this study we have reviewed the results of the first applications of interstitial laser photocoagulation for treatment of osteoid osteoma in Iranian patients. Materials and methods: In this case series study, we evaluated 9 known cases of osteoid osteoma that were referred for interstitial laser photocoagulation from orthopedic section of Imam Khomeini Hospital during 2001 and 2002. Diagnosis was confirmed by plain x-ray, cat scanning, isotope and MR scan. Interstitial laser photocoagulation was done by interventional radiologists of Medical Imaging Center. Percutaneous interstitial laser photocoagulation was performed by Nd-Yag laser, using 400-1000 joules energy (according to nidus size) and adjusting on 2 watts power. Results: The procedure was successful in all patients. We had pain relief in 24 hours. Follow up from 5 months to one year showed no recurrence. Conclusion: The procedure is a safe and effective method for patients and could be applied for proper cases

  1. CT-guided percutaneous laser photocoagulation of osteoid osteomas of the hands and feet

    Energy Technology Data Exchange (ETDEWEB)

    Zouari, Leila; Bousson, Valerie; Hamze, Bassam; Roqueplan, Francois; Laredo, Jean-Denis [Hopital Lariboisiere, Service de Radiologie Osteo-Articulaire, Paris (France); Roulot, Eric [Clinique Jouvenet, Institut de la main, Paris (France)

    2008-11-15

    Percutaneous local ablation of osteoid osteoma has largely replaced surgery, except in the small bones of the hands and feet. The objective of this study was to describe the technical specificities and results of computed tomography (CT)-guided percutaneous laser photocoagulation in 15 patients with osteoid osteomas of the hands and feet. We retrospectively examined the medical charts of the 15 patients who were treated with CT-guided percutaneous laser photocoagulation therapy at our institution between 1994 and 2004. The 15 patients had a mean age of 24.33 years. None of them had received any prior surgical or percutaneous treatment for the osteoid osteoma. The follow-up period was 24 to 96 months (mean, 49.93). The pain resolved completely within 1 week. Fourteen patients remained symptom-free throughout the follow-up period; the remaining patient experienced a recurrence of pain after 24 months, underwent a second laser photocoagulation procedure, and was symptom-free at last follow-up 45 months later. No adverse events related to the procedure or to the location of the tumor in the hand or the foot were recorded. CT-guided percutaneous laser photocoagulation is an alternative to surgery for the treatment of osteoid osteomas of the hands and feet. (orig.)

  2. Clinical periodontics with the argon laser

    Science.gov (United States)

    Finkbeiner, R. L.

    1995-04-01

    The argon laser has proven to be a valuable tool for the thermodynamic debridement of the periodontal lesion, incisions and tissue fusion. Illustrations of clinical applications and discussion of laser parameters will be provided.

  3. Outcomes of diode laser photocoagulation for aggressive posterior retinopathy of prematurity

    OpenAIRE

    Arvas, Sema; Akar, Solmaz; Sarıcı, Ahmet; Uçar, Didar

    2012-01-01

    Aim: Agressive posterior retinopathy of prematurity is a special subtype of retinopathy of prematurity Accurate and timely diagnosis and treatment could prevent further ocular and visual morbidity In this study we aimed to evalute the outcomes of agressive posterior retinopathy of prematurity treated with diode laser photocoagulation Material and Method: Records of preterm infants who were diagnosed as agressive posterior retinopathy of prematurity and treated with diode laser photocoagulatio...

  4. Argon Laser Photoablation for Postburn Conjunctival Pigmentation

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    Seong Joon Ahn

    2014-01-01

    Full Text Available We report a case of an ocular burn injury from boiling water which resulted in conjunctival pigmentation, 1 week following injury. For cosmetic purposes, 2 sessions of argon laser photoablation were performed. One month after laser treatment, conjunctival pigmentation had been successfully removed and the patient was very satisfied with the results. Argon laser photoablation may be an effective way to remove postburn conjunctival pigmentation.

  5. Posterior Pole Sparing Laser Photocoagulation Combined with Intravitreal Bevacizumab Injection in Posterior Retinopathy of Prematurity

    Directory of Open Access Journals (Sweden)

    Rebecca Kim

    2014-01-01

    Full Text Available Purpose. To report the results of the posterior pole sparing laser photocoagulation combined with intravitreal bevacizumab injection (IVB in retinopathy of prematurity (ROP. Methods. A retrospective chart review of premature babies with ROP, all of whom received laser photocoagulation with IVB. Eleven eyes of 6 infants with advanced zone I ROP underwent laser ablation sparing posterior pole with concurrent IVB. The results were compared with those of full-laser treatment combined with IVB to 8 eyes of 5 infants with advanced ROP without involvement of the posterior pole. Results. The posterior pole sparing laser with IVB was performed with zone I, stage 3+ ROP at the mean postmenstrual age of 36 weeks and 5 days. The plus sign decreased significantly at postoperative day 1, the neovascular proliferation regressed by postoperative week 1, and the normal vascularization started at postoperative day 32 on the average. Two months after treatment, vascularization of the spared avascular area was completed. There was no macular dragging, tractional retinal detachment, foveal destruction by laser scars, or any other adverse event. No significant anatomical differences were identified from those of full-laser ablation combined with IVB. Conclusions. Posterior pole sparing laser with IVB can give favorable results without destruction of posterior pole retina.

  6. Anatomical and Refractive Results of Diode Laser Photocoagulation in Retinopathy of Prematurity

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    K. Sadeghi

    2012-04-01

    Full Text Available Introduction & Objective: Retinopathy of prematurity (ROP is a major cause of blindness in premature newborns. It accounts for 4% of childhood blindness in developed countries and up to 40% in developing countries. The aim of this study is to report the refractive and anatomical outcome of patients who had undergone laser photocoagulate on for retinopathy of prematurity (ROP.Materials & Methods: In this cross sectional study, a total of forty eyes of twenty patients who had undergone transscleral diode laser photocoagulation for ROP between 2004-2008 were studied for the following measures: grade of ROP pre- and postoperatively, birth weight, gestational age, perioperative and postoperative complications, and current refraction.Results: Mean birth weight of patients was 923±271 gr and mean gestational age was 27.3±2.6 wk. All eyes had threshold ROP and responded to laser treatment with regression of ROP. Perioperative complications included hemorrhages in 15% that resorbed spontaneously. The mean age of patients at the time of examination for this study was 4.13±1.30 yr and their anatomical status of retina was normal. Strabismus (more than 20 prism diopter was found in 10% of patients. The spherical equivalent of refraction at the time of examination was -2.31±3.38 diopter.Conclusion: Photocoagulation for ROP in our patients resulted in regression of threshold ROP. In addition, the analyses of refractive outcome demonstrated a predominance of myopia and astigmatism.(Sci J Hamadan Univ Med Sci 2012;19(1:22-26

  7. Comparison of pain scores between patients undergoing panretinal photocoagulation using navigated or pattern scan laser systems

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    Umit Ubeyt Inan

    2016-02-01

    Full Text Available ABSTRACT Purpose: To compare the pain responses of patients with proliferative diabetic retinopathy (PDR undergoing panretinal photocoagulation (PRP using either pattern scan laser (PASCAL or navigated laser photocoagulation (NAVILAS. Methods: Patients diagnosed with PDR were randomly assigned to undergo either PASCAL or NAVILAS photocoagulation treatment. PRP was performed using the multi-shot mode with a spot size of 200-400 µm and a pulse duration of 30 ms to obtain a white-grayish spot on the retina. Parameters were identical in both procedures. After 30 min of PRP application, patients were asked to verbally describe their pain perception as either "none," "mild," "moderate," "severe," or "very severe" using a verbal rating scale (VRS and visual analog scale (VAS by indicating a score from "0" to "10," representing the severity of pain from "no pain" to "severe pain." Results: A total of 60 eyes of 60 patients (20 females and 40 males diagnosed with PDR were treated. The mean age of patients was 62.22 ± 9.19 years, and the mean diabetes duration was 195.47 ± 94.54 months. The mean number of laser spots delivered during PRP was 389.47 ± 71.52 in the NAVILAS group and 392.70 ± 54.33 in the PASCAL group (p=0.57. The difference in pain responses between patients in the NAVILAS and PASCAL groups was significant with regard to the mean VRS (1.10 ± 0.67 and 1.47 ± 0.69, respectively; p=0.042 and mean VAS (2.13 ± 1.17 and 2.97 ± 1.35, respectively; p=0.034 scores. Conclusions: Pain responses in patients undergoing PRP with a 30-ms pulse duration were significantly milder in the NAVILAS group than in the PASCAL group.

  8. Factors affecting reading speed in patients with diabetic macular edema treated with laser photocoagulation.

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    Elizabeth Pearce

    Full Text Available PURPOSE: To study the factors that may affect reading speed in patients with diabetic macular edema previously treated with laser photocoagulation. METHODS: Consecutive patients with type II diabetes treated with laser photocoagulation for diabetic macular edema (DME at least twelve months previously, with best corrected visual acuity of better than 65 letters (approximately 20/40 measured with Early Treatment Diabetic Retinopathy Study (ETDRS charts were included in this study. Patients previously treated with pan-retinal photocoagulation, vitrectomy, intravitreal steroid or anti-VEGF therapy were excluded. Any other ocular co-morbidities that may influence reading ability such as cataract, glaucoma or macular degeneration were also excluded. All patients were refracted by a certified examiner, the following measurements were collected: best corrected visual acuity (BCVA, contrast sensitivity with Pelli-Robson chart, reading speed with MNREAD chart, microperimetry with Nidek MP1, and central subfield thickness with Zeiss spectral domain optical coherent topography. RESULTS: The slow reading group had poorer contrast sensitivity (p = 0.001, reduced retinal sensitivity (p = 0.027 and less stable fixation (p = 0.013. Most interestingly the reduced retinal sensitivity findings were driven by the microperimetry value on the right subfield (p = 0.033, (nasal to the fovea in the right eye and temporal to the fovea in the left eye. Multiple linear regression analysis showed that contrast sensitivity is probably the most important factor that affects reading speed (p = 0.001. CONCLUSION: Reduced retinal sensitivity after laser treatment is associated with reduced reading speed in patients with diabetic macular edema.

  9. Krypton laser photocoagulation for neovascular lesions of age-related macular degeneration. Results of a randomized clinical trial. Macular Photocoagulation Study Group.

    Science.gov (United States)

    1990-06-01

    The Age-Related Macular Degeneration Study-Krypton Laser (AMDS-K) is a multicenter controlled clinical trial designed to determine whether krypton red laser photocoagulation is of value in preventing visual acuity loss in eyes with macular degeneration that have either choroidal neovascularization 1 to 199 microns from the center of the foveal avascular zone or choroidal neovascularization 200 microns or farther from the foveal avascular zone center with blood and/or blocked fluorescence extending within 200 microns of the foveal avascular zone center. Recruitment ended in December 1987 after 247 patients had been assigned to photocoagulation and 249 patients had been assigned to no treatment. At 3 years after randomization, 49% (86/174) of treated eyes, in contrast to 58% (98/169) of untreated eyes, had lost six or more lines of visual acuity. The average visual acuity of treated and untreated eyes at that time was 20/200 and 20/250, respectively. The benefit of laser treatment was largest among patients without evidence of hypertension and diminished to no apparent benefit among patients who had highly elevated blood pressure and/or used antihypertensive medication. Treatment of lesions meeting the AMDS-K eligibility criteria in eyes of patients with no hypertension is recommended. However, treatment cannot be recommended uniformly for patients with definite hypertension having lesions similar to those of patients enrolled in the AMDS-K. PMID:1693496

  10. Argon Laser Treatment of Strawberry Hemangioma in Infancy

    OpenAIRE

    Achauer, Bruce M.; Vander Kam, Victoria M.

    1985-01-01

    Argon laser therapy is effective for removing port-wine stains and for reducing cutaneous vascular and pigmented lesions. Strawberry hemangiomas, being much thicker lesions than port-wine stains, were considered not appropriate for argon laser treatment. Using argon laser therapy in 13 cases of strawberry hemangioma, we achieved poor to dramatic results.

  11. Argon laser treatment of strawberry hemangioma in infancy.

    Science.gov (United States)

    Achauer, B M; Vander Kam, V M

    1985-11-01

    Argon laser therapy is effective for removing port-wine stains and for reducing cutaneous vascular and pigmented lesions. Strawberry hemangiomas, being much thicker lesions than port-wine stains, were considered not appropriate for argon laser treatment. Using argon laser therapy in 13 cases of strawberry hemangioma, we achieved poor to dramatic results. PMID:4082569

  12. Recurrent twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a systematic review of the literature.

    LENUS (Irish Health Repository)

    Walsh, C A

    2012-11-01

    Selective fetoscopic laser photocoagulation (SFLP) is now the treatment of choice for twin-twin transfusion syndrome (TTTS). The incidence of recurrent TTTS following SFLP has been inconsistently reported across different studies. We performed a systematic review of TTTS recurrence following SFLP.

  13. Results of argon laser exposure of capillary hemangiomas of infancy--preliminary report.

    Science.gov (United States)

    Apfelberg, D B; Greene, R A; Maser, M R; Lash, H; Rivers, J L; Laub, D R

    1981-02-01

    Argon laser photocoagulation of capillary hemangiomas of infancy ("strawberry marks") has been described in three cases. Treatment in the first case was necessitated by repeated alarming hemorrhage. The second case was treated totally and resulted in immediate induced resolution of the hemangioma, which preceded (by 9 months) the spontaneous involution of an untreated control comparison area and resulted in virtually complete blanching without secondary deformity. The third case demonstrated the laser's ability to stop rapid growth immediately. Spontaneous involution then ensued naturally and was complete 12 months later. It should be emphasized that the argon laser is not recommended for the routine treatment of a normally spontaneously involuting hemangioma. Each case must be examined and the usual indications for intervention should be present. The argon laser has demonstrated the ability to coagulate vascular lesions such as port wine hemangiomas and telangiectasias and can be expected to have a similar favorable effect on the aggressive, rapidly expanding juvenile hemangioma, although further clinical documentation clearly remains to be demonstrated. PMID:7465667

  14. Argon laser application to endodontics

    Science.gov (United States)

    Blankenau, Richard J.; Ludlow, Marvin; Anderson, David

    1993-07-01

    The application of laser technology to endodontics has been studied for some time. At the present time several major problems are being investigated: (1) removal of infected tissues, (2) sterilization of canals, (3) obturation of canals, and (4) preservation of the vitality of supporting tissues. This list is not intended to imply other problems do not exist or have been solved, but it is a starting point. This paper reviews some of the literature that relates to laser applications to endodontics and concludes with some of the findings from our investigation.

  15. Argon laser irradiation of the otolithic organ

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, T.; Nomura, Y.; Young, Y.H.; Hara, M. (Univ. of Tokyo (Japan))

    1990-12-01

    An argon laser was used to irradiate the otolithic organs of guinea pigs and cynomolgus monkeys. After stapedectomy, the argon laser (1.5 W x 0.5 sec/shot) irradiated the utricle or saccule without touching the sensory organs. The stapes was replaced over the oval window after irradiation. The animals used for acute observation were killed immediately for morphologic studies; those used for long-term observation were kept alive for 2, 4, or 10 weeks. Acute observation revealed that sensory and supporting cells were elevated from the basement membrane only in the irradiated area. No rupture of the membranous labyrinth was observed. Long-term observation revealed that the otolith of the macula utriculi had disappeared in 2-week specimens. The entire macula utricili had disappeared in 10-week specimens. No morphologic changes were observed in cochlea, semicircular canals, or membranous labyrinth. The saccule showed similar changes.

  16. Abnormal epidermal changes after argon laser treatment

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, R.A.; Knobler, R.M.; Aberer, E.; Klein, W.; Kocsis, F.; Ott, E. (Univ. of Vienna (Austria))

    1991-02-01

    A 26-year-old woman with a congenital port-wine stain on the forehead was treated three times at 2-month intervals with an argon laser. Six months after the last treatment, moderate blanching and mild scaling confined to the treated area was observed. A biopsy specimen of the treated area revealed a significant decrease in ectatic vessels. However, epidermal changes similar to those of actinic keratosis with disorganized cell layers and marked cytologic abnormalities were seen. Analysis of peripheral blood lymphocytes for a defect in DNA repair was negative. Multiple, argon laser-induced photothermal effects may be responsible for the changes observed in our case and may lead to premalignant epidermal transformation.

  17. Argon laser-welded arteriovenous anastomoses.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; White, G; Lyons, R; Fujitani, R; Klein, S R; Uitto, J

    1987-11-01

    This study compared the healing of laser-welded and sutured canine femoral arteriovenous anastomoses. Arteriovenous fistulas 2 cm in length were created bilaterally in the femoral vessels of 10 dogs and were studied at 1 (n = 2), 2 (n = 2), 4 (n = 3), and 8 (n = 3) weeks. In each animal, one anastomosis (control) was closed with running 6-0 polypropylene sutures, and the contralateral anastomosis (experimental) was sealed with an argon laser (0.5 watt, 4 minutes of exposure, 1830 J/cm2/1 cm length of anastomosis). At removal all experimental anastomoses were patent without hematomas, aneurysms, or luminal narrowing. Histologic examination at 4 weeks revealed that laser-welded anastomoses had less inflammatory response and almost normal collagen and elastin reorientation. At 8 weeks sutured anastomoses had significant intimal hyperplasia whereas laser repairs had normal luminal architecture. Tensile strength and collagen production, measured by the synthesis of hydroxyproline and the steady-state levels of type I and type III procollagen messenger ribonucleic acids, at the anastomoses and in adjacent vein and artery specimens were similar in sutured and laser-welded repairs at 2, 4, and 8 weeks. We conclude that argon laser welding of anastomoses is an acceptable alternative to suture techniques, with the advantage of improved healing without foreign body response and possible diminished intimal hyperplasia at the anastomotic line. PMID:3312648

  18. Cooperative phenomena in two-pulse, two-color laser photocoagulation of cutaneous blood vessels.

    Science.gov (United States)

    Barton, J K; Frangineas, G; Pummer, H; Black, J F

    2001-06-01

    A novel laser system has been developed to study the effects of multiple laser pulses of differing wavelengths on cutaneous blood vessels in vivo, using the hamster dorsal skin flap preparation and in vitro, using cuvettes of whole or diluted blood. The system permits sequenced irradiation with well-defined intrapulse spacing at 532 nm, using a long-pulse frequency-doubled Nd:YAG laser, and at 1064 nm, using a long-pulse Nd:YAG laser. Using this system, we have identified a parameter space where two pulses of different wavelengths act in a synergistic manner to effect permanent vessel damage at radiant exposures where the two pulses individually have little or no effect. Using a two-color pump-probe technique in vitro, we have identified a phenomenon we call greenlight-induced infrared absorption, where a pulse of green light causes photochemical and photothermal modifications to the chemical constituents of blood and results in enhanced infrared absorption. We identify a new chemical species, met-hemoglobin, not normally present in healthy human blood but formed during laser photocoagulation which we believe is implicated in the enhanced near-infrared absorption. PMID:11421070

  19. Management of peripheral polypoidal choroidal vasculopathy with intravitreal bevacizumab and indocyanine green angiography-guided laser photocoagulation

    Directory of Open Access Journals (Sweden)

    Pukhraj Rishi

    2012-01-01

    Full Text Available A 69-year-old lady presented with complaints of decreased vision in left eye since one month. Best Corrected Visual Acuity (BCVA was 6/18 in that eye. Fundus examination revealed non-central geographic atrophy and soft drusens at macula in both eyes. Temporal periphery of left eye revealed subretinal exudates with altered sub-RPE hemorrhage mimicking peripheral exudative hemorrhagic chorioretinopathy (PEHCR. Fundus Fluorescein Angiogram showed window defects at macula and blocked fluorescence at temporal periphery in left eye. However, Indocyanine green angiography (ICGA revealed active peripheral choroidal polyps. The patient was successfully treated with intravitreal bevacizumab and ICGA-guided laser photocoagulation. 27 months after laser treatment, BCVA improved to 6/9. Rationale of consecutive anti-vascular endothelial growth factor (VEGF treatment followed by more definitive laser photocoagulation is that anti-VEGF aids in resolution of subretinal fluid, thus making the polyp more amenable to focal laser photocoagulation which stabilizes the choroidal vasculature and prevents further leakage.

  20. Large vessel sealing with the argon laser.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; Lyons, R; White, G; Klein, S R; Pizzurro, D; Abergel, R P; Dwyer, R M; Uitto, J

    1987-01-01

    This study compared the histology, biochemistry, and tensile strength of laser-welded and sutured canine venotomies, arteriotomies, and arteriovenous fistulas. Twelve animals had bilateral femoral vessels studied, with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralateral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks (four animals for each type of repair), and were evaluated histologically by hematoxylin and eosin, elastin, and trichrome stains; biochemically by the formation of [3H]hydroxyproline as an index of collagen synthesis; and mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms, or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welding may be an alternative to sutures for repair of large-diameter venotomies, arteriotomies, and arteriovenous fistulas, as healing is comparable to that seen with suture repairs up to 4 weeks postoperatively. PMID:3306233

  1. Vascular Welding Using The Argon Laser

    Science.gov (United States)

    White, Rodney A.; Donayre, Carlos; Kopchok, George; White, Geoffrey; Abergel, R. Patrick; Lyons, Richard; Klein, Stanley; Dwyer, Richard; Uitto, Jouni

    1987-03-01

    This study compared the histology, biochemistry, and tensile strength of laser welded and sutured canine venotomies, arteriotomies and arteriovenous fistulas. Bilateral femoral, carotid or jugular vessels were studied with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralatral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks for each type of repair and evaluated histologically by hematoxylineosin, elastin and trichrome stains, biochemically by the formation of [3H] hyaroxyproline as an index of collagen synthesis, ana mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welaing may be an alternative to sutures for repair of large diameter venotomies, arteriotomies and arteriovenous fistulas, as they heal comparable to suture repairs up to 4 weeks postoperatively.

  2. Long-term outcome following interstitial laser photocoagulation of benign cold thyroid nodules

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbæk, Finn Noe; Hegedüs, Laszlo

    2011-01-01

    Aim To evaluate the long-term efficacy of interstitial laser photocoagulation (ILP) in solitary benign thyroid nodules. Design and methods A total of 78 euthyroid outpatients (45 participating in randomized trials) with a benign solitary solid and scintigraphically cold thyroid nodule causing local...... discomfort were assigned to ILP. ILP (using one laser fiber) was performed under continuous ultrasound (US) guidance and with an output power of 1.5-3.5 W. Thyroid nodule volume was assessed by US and thyroid function determined by routine assays, before and during follow-up. Pressure symptoms and cosmetic...... complaints were evaluated on a visual analogue scale (0-10 cm). Of the total patients, six had thyroid surgery 6 months after ILP and three were lost to follow-up. The median follow-up for the remaining 69 patients was 67 months (range 12-114). Results The overall median nodule volume decreased from 8.2 ml...

  3. A STUDY ON THE SHORT TERM EFFECTS OF GRID LASER PHOTOCOAGULATION AND COMBINATION TREATMENT (GRID LASER WITH INTRAVITREAL BEVACIZUMAB IN THE MANAGEMENT OF DIABETIC MACULAR OEDEMA

    Directory of Open Access Journals (Sweden)

    Adil

    2016-05-01

    Full Text Available AIM To study the short term effect of grid laser photocoagulation in the treatment of diabetic macular oedema. As a comparison, the short term efficacy of combination treatment of grid laser photocoagulation along with intravitreal injection of bevacizumab was studied in the treatment of Diabetic Macular Oedema (DME. MATERIALS AND METHODS 74 eyes of 43 patients between the ages of 50-60 years with diabetic maculopathy were selected. These patients were then assigned to either groups of standalone photocoagulation therapy (Group I or combined therapy of photocoagulation with intravitreal Avastin (Group 2. Best Corrected Visual Acuity and Optical Coherence Tomography findings were done in all the patients during a follow-up done every four weeks up to twelve weeks. RESULTS In Group I, at the end of 12 weeks, overall 34% patients showed an improvement or stability in visual acuity. 66% of the patients had a decrease in visual acuity. The number of eyes with decline in visual acuity decreased during 4 to 12 weeks. 59.22% of the eyes showed improvement or stability in the visual acuity in Group 2. The mean central macular thickness remained stable or increased in 70.2% of the eyes, whereas the CMT decreased only in 29.8% eyes. But in Group 2, at the end of 12 weeks, 59.3% had a decrease in CMT. Total Macular Volume (TMV in Group I, decreased in 57.4% of the eyes. On the other hand, in Group 2 at 12 weeks, 59.3% showed a decrease in TMV, which is slightly better than in Group 1. CONCLUSION The patients with DME who underwent combined photocoagulation with intravitreal injection of Avastin showed significant improvement in visual acuity, central macular thickness and macular volume as compared to the patients who underwent standalone laser photocoagulation, though neither of the groups showed completely satisfactory improvement. Study with large number of patients and long term follow-up would be considered ideal.

  4. Effect of mitiglinide combined laser photocoagulation on blood glucose, blood lipid and vascular endothelial function in diabetic retinopathy

    Institute of Scientific and Technical Information of China (English)

    Yun-Yan Fan; Gui-Jun Luo

    2016-01-01

    Objective:To observe the effect of mitiglinide combined laser photocoagulation on blood glucose, blood lipid and vascular endothelial function in diabetic retinopathy.Methods:A total of 106 patients with diabetic retinopathy treated in our hospital from January 2014 to January 2015 were selected and assigned into the separate group and combined group. Fifty-three patients in the separate group only received oral mitiginide, while other 53 patients in the combined group received oral mitiglinide and laster photocoagulation surgery. Before and after treatment, the FBG, 2hPBG, HbA1c, TC, TG, HDL-C, LDL-C, ET-1, VEGF, PEDF, ICAM-1, FMD of patients in the two groups were analyzed.Results: After treatment, the blood glucose and blood lipid indexes of patients in the two groups were improved significantly, and there was no statistical difference between the two groups. The ET-1, ICAM-1 and VEGF of patients in the two groups decreased, and the decrease of the combined group was more distinctly. The PEDF and FMD in the two groups all increased, and the combined group changed more obviously. The regression of the blood vessel and the recovery of visual acuity in the combined group were better than the separate group.Conclusions:Mitiglinide combined with laser photocoagulation can effectively improve the level of blood glucose and blood lipid, promote vascular endothelial function and inhibit the formation of retinal neovascularization so as to improve the visual acuity level.

  5. Argon laser induced changes to the carbonate content of enamel

    International Nuclear Information System (INIS)

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm-2) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  6. Efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity Eficácia e segurança da fotocoagulação com laser verde na retinopatia da prematuridade limiar

    OpenAIRE

    Rodrigo Pessoa Cavalcanti Lira; Antônio Bezerra de Melo Calheiros; Manuela Maria Valença Cordeiro Barbosa; Cristiano Viana de Oliveira; Sabrina Lima Siqueira Viana; Danielle Cabral Lima

    2008-01-01

    PURPOSE: To report the efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity (ROP). METHODS: We reviewed the clinical records of the neonates who had undergone green laser photocoagulation for threshold ROP at the Federal University of Pernambuco in Brazil between January 2004 and January 2006. All procedures were conducted with local anesthetic drops. The neonates were monitored throughout the procedure by a neonatologist. A frequency-doubled solid stat...

  7. Treatment of lip hemangioma using forced dehydration with induced photocoagulation via diode laser: report of three cases.

    Science.gov (United States)

    Jasper, Juliana; Camilotti, Renata Stifelman; Pagnoncelli, Rogério Miranda; Poli, Vladimir Dourado; da Silveira Gerzson, Alexandre; Gavin Zakszeski, Ana Maria

    2015-03-01

    Several vascular lesions are related to the lip area. There is no universally accepted protocol for the treatment of hemangiomas and vascular malformations. In the oral cavity, high-power lasers represent an excellent therapeutic option for this type of lesion. Their coagulative properties allow for the performance of procedures without the risk of bleeding, which promotes a better healing pattern and a differentiated postoperative appearance. This study describes three cases of lip hemangioma treated with forced dehydration with induced photocoagulation (FDIP) via diode laser. All the reported cases were followed up until complete healing of the operated area had total remission of lesions, with no complications or adverse effects. The findings of the present study suggest that FDIP is effective and useful in the treatment of hemangiomas in the oral cavity. Laser treatment of these lesions prevents their recurrence and is well tolerated by patients.

  8. Green laser photocoagulator for the treatment of diabetic retinopathy developed at Raja Ramanna Centre for Advanced Technology

    Indian Academy of Sciences (India)

    S M Oak

    2010-12-01

    An all-solid-state green laser photocoagulator at 532 nm with output power varying from 100 mW to 1 W in a step of 10 mW and exposure time varying from 50 ms to 1000 ms in a step of 10 ms is developed for the treatment of diabetic retinopathy. The output power stability is better than ± 1.5% with a nearly diffraction-limited beam quality. The system includes various safety and operational features like internal power monitoring system, safety interlock, emergency switch-off, graphical LCD display with table-top touch mode portable control panel, smart delivery device selection, aiming laser beam with controllable intensity, foot switch, patient records, service mode etc. The system has successfully passed the clinical trials and is being used on patients.

  9. Clinical analysis of laser photocoagulation for diabetic retinopathy%糖尿病视网膜病变激光光凝治疗疗效分析

    Institute of Scientific and Technical Information of China (English)

    张志红; 王媛媛; 曹江欣

    2013-01-01

    目的探讨激光光凝治疗糖尿病视网膜病变(DR)的疗效。方法 以DR患者54例108眼为研究对象,对增殖期(PDR)96眼行标准全视网膜光凝,非增殖期(NPDR)22眼行弥漫视网膜光凝。结果 视力提高或不变90眼,有效率83.3%。FFA检查示有效率86.1%。结论 激光光凝术是治疗DR 的一个有效方法,要把握光凝时机,争取早期发现并及时治疗DR,提高激光光凝的疗效。%Objective :To evaluate the efficacy of laser coagulation for diabetic retinopathy. Method :Total 54 patients (108 eyes) of diabetic retinopathy were as the object of this study. 96 eyes with proliferative diabetic retinopathy (PDR) were given panretinal photocoagulation. 22 eyes with non-proliferative diabetic retinopathy(NPDR)were given scatter photocoagulation.Results : the eyes of vision improve or no change are 90,totle effective rate is 83.3. totle effective rate of FFA examination is 86.1%. Conclusion: Laser photocoagulation is an effective method for diabetic retinopathy. It has different efficacy for the different stages of diabetic retinopathy. It can improve the efficacy of laser photocoagulation that we seize the opportunity of laser photocoagulation for diabetic retinopathy,early detecting and timely treating diabetic retinopathy.

  10. A therapeutic experience on Port Wine hemangiomas with Argon Laser

    Directory of Open Access Journals (Sweden)

    Farahvash M

    1997-09-01

    Full Text Available Port wine stains are benign but cosmetically devasting congenital angiomas. The argon laser is a therapeutic device newly applied to this condition. Our program was begun 6 years ago. From the beginning, the study was conceived as a clinical investigation of both the port wine stain and its argon laser therapy. A total of 218 patients with port wine stains have been studied and many aspects of their clinical condition detailed. Employing the Argon laser, test spots have been carried out in patients and the results have been analyzed with clinical aspects of the lesions. Altogether, 501 treatments were performed in 218 patients. Good to excellent results were obtained in 81 patients. Moderate Result was obtained in 31 weak result in 65 patients. Most common complication were hyperpigmentation and depressed scar.

  11. Effect of ultrasound-guided interstitial laser photocoagulation on benign solitary solid cold thyroid nodules - a randomised study

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbaek, Finn Noe; Hegedüs, Laszlo

    2005-01-01

    AIM: To evaluate the efficacy of ultrasound (US)-guided interstitial laser photocoagulation (ILP) on thyroid function, nodule size and patient satisfaction in benign solitary solid cold thyroid nodules by comparing one ILP session with no treatment in a prospective randomised study. MATERIALS...... AND METHODS: Thirty euthyroid outpatients with a benign solitary solid and a scintigraphically cold thyroid nodule causing local discomfort were assigned to one session of ILP (n = 15) or observation (n = 15) and followed for 6 months. Thyroid nodule volume and total thyroid volume were assessed by US...... and thyroid function was determined by routine assays before and during follow-up. Pressure and cosmetic complaints before and at 6 months were evaluated on a visual analogue scale. ILP was performed under US guidance and with an output power of 2.5-3.5 W. RESULTS: In the ILP group, the nodule volume...

  12. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  13. Narrow spectral width laser diode for metastable argon atoms pumping

    Science.gov (United States)

    Gao, Jun; Li, Bin; Wang, Xinbing; Zuo, Duluo

    2016-03-01

    Diode laser pump source with narrow emitting spectrum for optically pumped metastable rare gas laser (OPRGL) of argon was achieved by employing a complex external cavity coupled with volume Bragg grating (VBG). A commercially available c-mount laser diode with rated power of 6 W was used and studied in both the free running mode and VBG external cavity. The maximum output power of 3.9 W with FWHM less than 25 pm and peak wavelength locked around 811.53 nm was obtained from the VBG external cavity laser diode. Precise control of VBG temperature enabled fine tuning of the emission wavelength over a range of 450 pm. Future researches on OPRGL of argon will benefit from it.

  14. Comparison of anesthesia with sevoflurane-N2O and midazolam-remifentanil in low-birth-weight premature infants undergoing diode laser photocoagulation

    OpenAIRE

    BUT, Abdulkadir; Arikan, Müge; ASLAN, Bilge; Öztürk, Levent; TABUK, Meltem; HORASANLI, Eyüp

    2012-01-01

    Aim: The present study aimed to compare anesthesia with sevoflurane-N2O and midazolam-remifentanil in terms of hemodynamic parameters and safety in low-birth-weight (LBW) premature infants undergoing diode laser photocoagulation (DLP) for retinopathy of prematurity (ROP). Materials and methods: A total of 91 infants undergoing DLP for ROP were enrolled in this study. All of the infants were established with LBW (

  15. Photocoagulation as treatment of diabetic retinopathy

    Science.gov (United States)

    Sanchez, J.; Fernandez, L.; de Pedraza, Maria L.; Gamella, C.; Santervas, R.

    1992-03-01

    Diabetes Mellitus is a chronic disease that is revealed with a lot of alterations due to factors such as an absolute or relative reduction of the insulin. It is usually accompanied by generalized arteriosclerosis and prepares for certain microvasculares pathologies such as retinopathy, nefropathy, and neuropathy. The first effects of diabetes in the retina seem to act on the capillaries. The functional modifications of the retinal circulation appear before the structural ones. These consist of the blood flux damage and the obligation of the hematorretinal barrier with extravasacy as can be proved in the fluorophotometry of the vitreous humor. Nowadays, medical treatments are more effective and only vitrectomy and photocoagulation are used in diabetic retinopathy. For that, the argon laser and the xenon arch are used. The treatment is usually spread panretine, with coagulation in a grid pattern around the eye, avoiding the macula and other vital structures, and treating the neoformed blood vessels. The rate of grave visual loss in the studies carried out with there techniques was 12 in relation to 28 in the non-treated cases. The most important factors of risk found, were the discal neoformed blood vessels and the hemorrhage of the vitreous humor. Adverse effects were found such as the reduction of visual sharpness and the contrition of the visual field, these are greater in patients treated with the xenon arch than in those treated with the argon laser.

  16. High intensity, argon ion laser-jet photochemistry

    Science.gov (United States)

    Wilson, R. Marshall; Schnapp, Karlyn A.; Hannemann, Klaus; Ho, Douglas M.; Memarian, Hamid R.; Azadnia, Ardeshir; Pinhas, Allan R.; Figley, Timothy M.

    A new technique for the study of high intensity solution photochemistry has been developed. With this laser-jet technique, a high velocity microjet is irradiated with the focussed output of an argon ion laser. Under these extremely high intensity conditions, photochemically generated transient species with suitable absorption properties are excited further and produce relatively large amounts of photoproducts which are not observed under low intensity conditions. The application of this laser-jet technique in the study of the photochemistry of radicals, biradicals, photoenols and the higher excited states of carbonyl and polycyclic aromatic compounds is described.

  17. Primary study of micropulse diode laser photocoagulation for central serous chorioretinopathy%微脉冲半导体激光治疗CSC的初步观察

    Institute of Scientific and Technical Information of China (English)

    徐建锋; 叶瑞珍; 李贵洲

    2013-01-01

    AIM: To investigate the effect of micropulse diode laser photocoagulation on central serous choroidretinopathy (CSC). METHODS: Twelve patients diagnosed with CSC by fluorescein angiography ( FFA) and optic coherence tomography ( OCT) examination were treated with micropulse diode laser photocoagulation. The data of visual acuity testing, ophthalmic examination, color photographs, FFA and OCT before photocoagulation and 1 week, 2 weeks, 1 month, 3 months after it were used to evaluate the effects of micropulse diode laser photocoagulation. RESULTS: All patients' self-conscious symptom and visual acuity improved differently. Nine and eleven eyes leakage point disappeared after micropulse diode laser photocoagulation in 2 weeks and one month in FFA. Nine and eleven eyes of subretinal effusion in OCT were absorbed after laser photocoagulation in 2 weeks and one month. All cases' leakage point and subretinal effusion disappeared after 3 months. The window defect in FFA did not occur in all laser treated eyes. CONCLUSION: The micropulse diode laser photocoagulation could shorten the course of CSC, improve the patient's visual acuity and reduce the complications.%目的:探讨微脉冲半导体激光治疗中心性浆液性脉络膜视网膜病变(central serous chorioretinopathy,CSC)的疗效.方法:自身对照病例研究.将经荧光素眼底血管造影(fundus fluorescein angiography,FFA)和光学相干断层扫描(optic coherence tomography,OCT)检查确诊的典型性CSC患者12例12眼行微脉冲半导体激光治疗前及治疗后随访观察1,2wk;1,3mo的临床资料进行分析,主要以治疗前后的视力、自觉症状、眼底情况、FFA及OCT检查的改变为观察指标,以评价微脉冲半导体激光对CSC的治疗效果.结果:所有患者自觉症状减轻或消退,视力及视觉质量均有不同程度改善.激光光凝2wk和1mo后,分别有9眼(75.0%)和11眼(91.7%)的黄斑区水肿完全消退,3mo后全部患者黄斑区水肿消退.光凝2

  18. Treatment of facial vascular lesions with an argon laser

    Science.gov (United States)

    Szymanczyk, Jacek; Golebiowska, Aleksandra; Michalska, I.

    1996-03-01

    Two-hundred-ninety-six patients with various vascular lesions of the face have been treated with argon laser LAK-1 in the Department of Dermatology Warsaw Medical Academy since April 1992. The diagnosis of the treated lesions was port-wine stains, multiple telangiectasiae and small, most often induced by trauma hemangioma cavernosum of the lip. Best results were achieved in the patients with small hemangiomas cavernosum of the lip and multiple telangiectasiae on the face. Cure rate in this group was 100%. In 112 port-wine stain cases fading of 50 - 75% comparing with the adjacent skin was achieved. With stress, the argon laser therapy is a method of choice for the treatment of hemangioma cavernosum, port-wine stains and multiple teleagiectasiae of the face.

  19. Argon Laser Photoablation for Treating Benign Pigmented Conjunctival Nevi

    Science.gov (United States)

    Alsharif, Abdulrahman M.; Al-Gehedan, Saeed M.; Alasbali, Tariq; Alkuraya, Hisham S.; Lotfy, Nancy M.; Khandekar, Rajiv

    2016-01-01

    Purpose: To evaluate the outcomes of argon laser photoablation of benign conjunctival pigmented nevi with different clinical presentations. Patients and Methods: This interventional case series was conducted between July 2014 and January 2015. Patients presenting with benign conjunctival nevi were included. Data were collected on the clinical features at presentation, argon laser photoablation, and follow-up at 8 and 24 weeks. Postoperative photography allowed recording of the success of each case and the overall success rate. Complete removal of conjunctival pigments was considered an absolute success. Partial pigmentation requiring repeat laser treatment was considered a qualified success. Results: There were 14 eyes (four right eyes and ten left eyes) with benign pigmented conjunctival nevi. There were three males and eight females in the study sample. The median age was 36 (25% percentile: 26 years). Three patients had bilateral lesions. The nevi were located temporally in nine eyes, nasally in three eyes, and on the inferior bulbar conjunctiva in two eyes. The mean horizontal and vertical diameters of nevi were 5 ± 2 mm and 4 ± 2.7 mm, respectively. The mean follow-up period was 5 months. Following laser treatment, no eyes had subconjunctival hemorrhage, infection, scarring, neovascularization, recurrence, or corneal damage. The absolute success rate of laser ablation was 79%. Three eyes with elevated nevi had one to three sessions of laser ablation resulting in a qualified success rate of 100%. Conclusions: Argon laser ablation was a safe and effective treatment for the treatment of selective benign pigmented conjunctival nevi in Arab patients. PMID:27555708

  20. Improved external valvuloplasty, intravenous laser photocoagulation and local sclerotheraphy treatment of primary deep venous valvular insufficiency: long term result

    Science.gov (United States)

    Wang, Chun-xi; Han, Li-na; Gu, Ying; Liang, Fa-qi; Zhang, Li; Liu, Hong-yi; Zhao, Wen-guang; Wang, Qi; Wang, Xiao-ling

    2007-11-01

    The purpose of this article is to report long-term follow-up of improved external vulvuloplasty, intravenous laser photocoagulation and local sclerotherapy treatment of primary deep venous valvular insufficiency in eight hundred and seventy-two patients from Nov. 2000 to May 2006. Patients were evaluated clinically and with duplex ultrasound at 1, 3, and 12 months, and yearly thereafter until the fifth year to assess treatment efficacy and adverse reactions. Successful occlusion of the great saphenous vein and absence of deep vein reflux on color Doppler imaging, were noted in 956 limbs of 852 cases( 1 month follow-up), 946 limbs of 842 cases (6 month to 1 year follow-up), 717 of 626 (1~2 year follow-up), 501 of 417 (2~3 year follow-up), 352 of 296 (3~5year follow-up), 142 of 106 (5 year follow-up) after initial treatment. The cumulative total number of recurrence of reflux was fifteen cases. The respective competence rate was 95.18%, 96.23%, 94.23%, 95.25%, 94.23% and 94.12%. Of note, all recurrence occurred before 9 months, with the majority noted before 3 months. Bruising was noted in 0.7% of patients, tightness along the course of treated vein in 1.0% of limbs. There have been no paresthesia of cases, skin burns and deep vein thrombosis.

  1. Ultrasound-guided interstitial laser photocoagulation of an autonomous thyroid nodule: the introduction of a novel alternative.

    Science.gov (United States)

    Døssing, Helle; Bennedbaek, Finn Noe; Hegedüs, Laszlo

    2003-09-01

    Radioiodine ((131)I) and surgery are the standard therapeutic options for the solitary autonomous thyroid nodule (AFTN). Percutaneous ethanol injection (PEI) has proven to be an effective technique and possible alternative to the conventional treatment options. However, PEI is not devoid of side effects and often necessitates multiple treatment sessions. We present a case of a 17-year-old female successfully treated with ultrasound (US)-guided percutaneous interstitial laser photocoagulation (ILP) for an AFTN. Initially, she had a serum thyrotropin (TSH) of 0.01 mU/L and normal peripheral thyroid hormone levels. Scintigraphically it was a hot nodule with suppression of extranodular uptake, and ultrasonographically it was a solitary solid 8.2-mL nodule. One treatment session (3 W for 650 seconds [1950 J]) normalized serum thyrotropin (TSH) level within 2 months and decreased the nodule volume to 4.9 mL (40% reduction) without further alterations during an additional 9 months of follow-up. Side effects were transient thyrotoxicosis and local pain as seen with PEI. To our knowledge, this is the first reported case of ILP used in a patient with a pretoxic thyroid nodule. US-guided thermic tissue coagulation with ILP could become a useful alternative for the AFTN in patients who cannot or will not undergo surgery or treatment with (131)I. PMID:14588105

  2. Laser-induced vibrational dynamics of ozone in solid argon

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Amstrup, B.; Henriksen, Niels Engholm

    1997-01-01

    We consider the vibrational dynamics, induced by an intense infrared laser pulse, in an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18 and compare the dynamics in the gas phase and in solid ar on. not perturbed by argon on a time-scale of a few picoseconds and selective...... bond-breaking in the molecule should be possible following the same laser control scheme as suggested in the gas phase. (C) 1997 Elsevier Science B.V....

  3. Argon laser in the treatment of diabetic retinopathy (Preliminary communication)

    International Nuclear Information System (INIS)

    The complications observed in the photocoagulation treatment of diabetic angiopathy and retinopathy include the following conditions: tractional retinal detachment, accelerated development of proliferating retinitis and massive hemmorrhaging into the vitreous body. (V.A.P.)

  4. Relation between skin surface temperature and minimal blanching during argon, Nd-YAG 532, and CW dye 585 laser therapy of port-wine stains.

    Science.gov (United States)

    Mordon, S; Beacco, C; Rotteleur, G; Brunetaud, J M

    1993-01-01

    Laser photocoagulation has proven to be valuable in the treatment of port-wine stains. In this application, the minimal blanching technique is used as an indicator of suitable dosage since it has been demonstrated that the immediate appearance a white mark is required to achieve permanent blanching a few months later. The objective of the investigations undertaken in this study was to correlate the temperature attained at the surface of port-wine stains with immediate blanching, upon irradiation with different laser fluences. A comparative study was performed using an argon laser (all lines), a 532 nm Nd:YAG and a 585 nm argon pumped dye laser. Surface temperature was studied using an infrared camera. Temperature was measured on 10 different port-wine stains using different fluences. Whitening threshold fluence was related to surface temperature. It appeared that whitening threshold fluence corresponded to a surface temperature of 53 degrees C (+/- 3 degrees C). The whitening threshold fluence was dependent on port-wine stains and wavelength. However, whitening threshold fluence remained lower for 532 nm and 585 nm and it correlated to the absorption curve of hemoglobin.

  5. The predictive value of optical coherence tomography after grid laser photocoagulation for diffuse diabetic macular oedema

    DEFF Research Database (Denmark)

    Soliman, W.; Sander, B.; Soliman, K.A.E.N.;

    2008-01-01

    Purpose: To assess the predictive value of optical coherence tomography (OCT) mapping of retinal thickness and intraretinal morphological changes after macular grid for diffuse diabetic macular oedema (DMO). Methods: We carried out a prospective, non-controlled, case series study, in which 28 con...... patterns and foveal thickness can help to predict the final visual outcome and final foveal thickness; but not the absolute change in either of these parameters after macular laser therapy Udgivelsesdato: 2008/5......'s correlation coefficient (r = - 0.37, p = 0.05 and r = 0.5, p = 0.01, respectively). Conclusions: it seems that the 1-month time-point after macular laser treatment is a critical point for establishing the outcome of this modality of management of DMO. Baseline OCT mapping of intraretinal fluid accumulation...

  6. Clinical features of neovascular glaucoma treated with multi-wavelength laser photocoagulation%多波长激光视网膜光凝治疗新生血管性青光眼的临床特点

    Institute of Scientific and Technical Information of China (English)

    吕刚; 唐连志; 张伟; 王涛; 黄红深

    2013-01-01

    目的:观察新生血管性青光眼(neovascular glaucoma,NVG)应用多波长激光进行全视网膜光凝(pan retinal photocoagulation,PRP)的临床特点.方法:NVG患者21例25眼积极抗青光眼治疗同时,应用多波长激光进行PRP,观察光凝特点及并发症.结果:所有患者PRP顺利完成,应用红光光凝较多,光凝时明显疼痛3例5眼,虹膜炎症反应2例3眼,前房和玻璃体少量出血4例4眼,未发生脉络膜视网膜脱离.眼压不同程度下降,眼痛、头痛症状缓解.结论:多波长激光有利于NVG患者PRP的顺利完成,且安全有效.%AIM: To observe clinical features of neovascular glaucoma ( NVG) treated with multi - wavelength laser photocoagulation (PRP).METHODS: Totally 21 patients (25 eyes) with NVG were performed actively anti-glaucoma treatment, at the same time, they were also performed multi-wavelength laser photocoagulation. Photocoagulation characteristics and complications were observed.RESULTS: The PRP was completed successfully on alleyes. Red photocoagulation was used more offen. Three cases (5 eyes) had obvious pain, 2 cases (3 eyes) had iris inflammation reaction, 4 cases (4 eyes) had anterior chamber and vitreous hemorrhage. Choroidal retinal detachment was not found. IOP was decreased at different degree, eye pain and headache symptoms were relieved.CONCLUSION; Multi-wavelength laser is conducive to the successful completion of pan retinal photocoagulation in neovascular glaucoma. It is safe and effective.

  7. Effect of laser photocoagulation and bevacizumab intravitreal in proliferative diabetic retinopathy: review on biomarkers of oxidative stress

    Directory of Open Access Journals (Sweden)

    Andi A. Victor

    2014-06-01

    Full Text Available Background: This study was aimed to compare the effect of laser photocoagulation (LF, intravitreal bevacizumab (IVB and combined treatments on biomarkers of oxidative stress such as aldehhyde dehidrogenase (ALDH, malondialdehyde (MDA level, superoxide dismutase (SOD activities, and vitreal vascular endothelial growth factor (VEGF on proliferative diabetic retinopathy (DR patients.Methods: In this single blind randomized clinical trial, 72 eyes from 69 cases of proliferative DR in Cipto Mangunkusumo Hospital between February 2011 - June 2013 were randomized into 4 groups : 1 control (n = 18; 2 LF pre-vitrectomy (n = 18; 3 IVB pre-vitrectomy (n = 18; and 4 combined IVB and LF pre-vitrectomy (n = 18. One-way ANOVA was used to compare oxidative stress parameters in the four groups.Results: There were no statistically significant differences in the average plasma ALDH activity (0.034 ± 0.02; 0.027 ± 0.02; 0.025 ± 0.02; 0.031 ± 0.11 IU/mg protein; p = 0.66, vitreal MDA level (1.661 ± 1.21; 1.557 ± 1.32; 1.717 ± 1.54; 1.501 ± 1.09 nmol/mL; p = 0.96 and SOD activity (0.403 ± 0.50; 0.210 ± 0.18; 0.399 ± 0.49; 0.273 ± 0.32 U/mL; p = 0.38 among these four groups, respectively. However, the VEGF vitreal level (pg/mL showed a statistically significant difference (0.356 ± 0.60; 0.393 ± 0.45; 0.150 ± 0.24; 0.069 ± 0.13; p = 0.05. The VEGF level in combination group was five times lower than the control group (p = 0.05.Conclusion: Combined treatments of DR by IVB and LF were correlated with lower vitreal MDA and plasma VEGF level, but did not have any effect on plasma ALDH and vitreal SOD in proliferative DR. Combined treatments with IVB and LF are recommended for the management of proliferative DR patients.  

  8. O uso do laser de argônio no tratamento da triquíase Argon laser in the treatment of trichiasis

    Directory of Open Access Journals (Sweden)

    Nilson Lopes da Fonseca Junior

    2004-04-01

    Full Text Available OBJETIVO: Avaliar a eficácia da técnica de termoablação dos folículos pilosos dos cílios em triquíase com laser de argônio e observar a preferência dos pacientes submetidos a este tratamento, pela anestesia tópica com colírio anestésico ou pela anestesia local injetável. MÉTODOS: Estudo prospectivo de 55 pálpebras de 39 pacientes com triquíase, tratados com fotocoagulação dos folículos pilosos com "Argon green laser" (Alcon® - EUA. Neste estudo avaliou-se a idade e o sexo dos pacientes, o número de sessões realizadas, a evolução após as aplicações e a preferência pelo tipo de anestesia. Os parâmetros utilizados foram: (1 Mira - 150 µm; (2 Potência- 750 mW; (3 Tempo de exposição- 0,2 s. Cada cílio recebeu, no máximo, 9 disparos por sessão. RESULTADOS: Dentre os 39 participantes do estudo, 58,9% eram do sexo feminino e 41% do sexo masculino. A idade média foi de 71 anos. Houve cura em 69% (38 pálpebras, sendo 29% (16 pálpebras com apenas uma sessão de laser. Houve preferência estatisticamente significativa pelo procedimento realizado sob anestesia local injetável. CONCLUSÃO: Os resultados sugerem que a anestesia local no tratamento da triquíase com laser de argônio é a preferência da maioria dos pacientes e que a termoablação dos folículos pilosos com laser de argônio é tratamento efetivo para a triquíase.PURPOSE: To evaluate the effectiveness of thermoablation of eyelashes in trichiasis with Argon laser and to observe the patients' choice of topic or local anesthesia. METHODS: Prospective study of 55 eyelids of 39 patients with trichiasis treated with photocoagulation of the eyelash follicle with Argon green laser (Alcon® - USA. Age, sex, number of applications in each session, evolution after the application and preference for the anesthesic method were evaluated. The laser settings were: 150 µm aim 750 mW potency; 0.2 seconds exhibition. Each eyelash received no more than 9 applications per

  9. Physiological responses of Vigna radiata L. to nitrogen and argon+ laser irradiation - Short Communication

    International Nuclear Information System (INIS)

    The effect of nitrogen laser (337.1 nm) and argon+ laser (514.5 nm) irradiation on physiological responses in the green gram seedlings was studied. The shoot and root lengths and fresh and dry weights of the seedlings increased with 30 min exposure to nitrogen laser and 5 min exposure to Argon+ laser. Protein content was maximum with 20 min exposure to N laser and 5 min exposure to Ar+ laser, while DNA and RNA contents were maximum at 5 min exposure with both the laser treatments

  10. Picosecond-laser-driven gas puff neonlike argon x-ray laser

    International Nuclear Information System (INIS)

    We have performed short-pulse laser-irradiated gas puff target experiments to generate a neonlike argon soft-x-ray laser by using a small laser system. A high-pressure solenoid valve forms a gas column through a narrow slit that is irradiated by two laser pulses containing 10 J of energy. Strong lasing is observed on two transitions, the 3p 1S0→3s 1P1 line at 46.9 nm and the 3d 1P1→3p 1P1 line at 45.1 nm. We present results from a systematic study in which the gas puff and laser conditions were varied to optimize the x-ray-laser output from a 0.9-cm-long gas column

  11. Retinopexia pneumática e fotocooagulação a laser para tratamento de descolamento secundário à fosseta de disco óptico: relato de caso Pneumatic retinopexy and laser photocoagulation for treatment of optic disc pit detachment: case report

    Directory of Open Access Journals (Sweden)

    Alexandre Antonio Marques Rosa

    2006-02-01

    Full Text Available Os autores relatam o caso de um paciente com fosseta congênita de disco óptico associado a descolamento seroso macular, tratado com sucesso por meio de fotocoagulação com laser de argônio na borda temporal da fosseta, seguido de injeção intravítrea de 0,3 ml de C3F8 (100%. O paciente foi seguido por 12 meses. A resolução do descolamento foi acompanhada de melhora da acuidade visual, bem como o retorno da fóvea a sua configuração normal, comprovada através da tomografia de coerência óptica.The authors report a case of congenital optic disc pit with serous macular detachment successfully treated, with argon laser photocoagulation in the temporal border of the pit, followed by intravitreous injection of C3F8 (100% 0.3 ml. Patient was followed up for 12 months. Retinal reattachment was associated with improvement in visual acuity, as well as return of the fovea to its normal configuration shown by optical coherence tomography.

  12. Curative Effect Observation of Anti VEGF Drugs Combined Laser Photocoagulation in Treatment of Diabetic Macular Edema%抗VEGF药物联合激光光凝治疗糖尿病黄斑水肿的疗效观察

    Institute of Scientific and Technical Information of China (English)

    张凤; 王琇; 公慧敏

    2015-01-01

    目的:分析和研究抗 VEGF 药物联合激光光凝治疗糖尿病黄斑水肿的疗效。方法选取2012年8月~2014年9月糖尿病黄斑水肿患者44例,分为抗 VEGF +光凝组与光凝组,光凝组患者给予激光光凝;抗 VEGF +光凝组患者给予抗 VEGF 药物联合激光光凝治疗,对比治疗前和治疗6个月两组最佳矫正视力(BCVA)、黄斑中心凹厚度(CMT)、安全性和注射次数。结果治疗前,两组患者两组 BCVA 水平、CMT 水平经 t 检验显示差异无统计学意义(P >0.05)。治疗6个月两组 BCVA 水平均提高、CMT 水平均降低,经 t 检验显示差异有统计学意义(P <0.05),但抗 VEGF +光凝组 BCVA 水平、CMT 水平改善幅度优于光凝组,经t 检验显示差异有统计学意义(P <0.05)。经随访,光凝组和抗 VEGF +光凝组均未出现视网膜脱落、眼内炎、晶状体损伤、眼压升高、玻璃体积血、色素上皮撕裂、地图状萎缩等眼部不良反应或中风、心脏病等全身不良反应,组间经χ2检验显示差异无统计学意义(P >0.05)。结论抗 VEGF 药物联合激光光凝治疗糖尿病黄斑水肿的疗效确切,可改善患者视力和视网膜厚度。%Objective To analyze and research of VEGF drugs combined laser photocoagulation for treatment of diabetic macular edema. Methods Selected 44 patients with diabetic macular edema in August 2012 to September 2014,divided into anti VEGF+photocoagulation and photocoagulation group. Photocoagulation group patients given laser photocoagulation. Anti VEGF + photocoagulation group patients given fight VEGF drugs combined laser photocoagulation for treatment,compared before and 6 months after treatment in the two groups best corrected visual acuity(BCVA)and macular center concave thickness(CMT),security,and injection time. Results Before the treatment,two groups of patients,the CMT the BCVA level two groups of t test showed that

  13. Efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity Eficácia e segurança da fotocoagulação com laser verde na retinopatia da prematuridade limiar

    Directory of Open Access Journals (Sweden)

    Rodrigo Pessoa Cavalcanti Lira

    2008-02-01

    Full Text Available PURPOSE: To report the efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity (ROP. METHODS: We reviewed the clinical records of the neonates who had undergone green laser photocoagulation for threshold ROP at the Federal University of Pernambuco in Brazil between January 2004 and January 2006. All procedures were conducted with local anesthetic drops. The neonates were monitored throughout the procedure by a neonatologist. A frequency-doubled solid state laser, diode-pumped, with 532 nm wavelength was used. The presence of tunica vasculosa lentis or cataract were excluded before laser treatment. The following preoperative data were obtained for each patient: age, birth weight and the grade of ROP. Postoperative data included complications associated with the laser treatment, grade of ROP and evaluation whether further surgery was necessary due to failure of laser photocoagulation. RESULTS: Twenty-two neonates underwent photocoagulation with green laser for threshold ROP. A total of 31 eyes were included in the study. The mean gestational age was 30 ± 3 weeks and the mean birth weight was 1120 ± 490 g. Regression of the disease after laser therapy was observed in 30 eyes (96.7%. Despite treatment one eye presented stage 4A. Only 7 eyes required repetitive laser therapy. No adverse effects such as burning anterior segment tissues or bleeding in the anterior chamber occurred. No posterior segment side-effects were observed. Cataract formation was not observed at the last follow-up examination. CONCLUSIONS: Green laser photocoagulation remains an effective and safe alternative to red laser photocoagulation and to cryotherapy in the treatment of threshold ROP.OBJETIVOS: Avaliar a eficácia e segurança da fotocoagulação com laser verde na retinopatia da prematuridade (ROP limiar. MÉTODOS: Foram revisados prontuários dos neonatos submetidos à fotocoagulação com laser verde para ROP limiar, na

  14. Effect of argon on the performance of a fast-axial flow CO2 laser

    Science.gov (United States)

    Jelvani, S.; Amiri, Kh; Pazokian, H.; Montazerolghaem, M.; Mollabashi, M.; Naeimi, S. A.; Esmaeilpour, D.

    2011-01-01

    The performance characteristics of a fast-axial flow (FAF) cw CO2 laser are described. The dependences of the output power, efficiency, and discharge voltage on the discharge current of a FAF cw CO2 laser with optimised composition of the CO2:N2:He=1:4.4:7.6 gas mixture with a small amount of argon are studied experimentally at two pressures of 50 and 60 mbar in open and closed cycle regimes of the laser system.

  15. Argon laser phototherapy of human malignancies using rhodamine-123 as a new laser dye: The intracellular role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Castro, D.J.; Saxton, R.E.; Markley, J.; Foote, C.S.; Fetterman, H.R.; Castro, D.J.; Ward, P.H. (Univ. of California, Los Angeles (USA))

    1990-08-01

    Recent studies demonstrated that the cationic, mitochondrial-specific dye Rhodamine-123 (Rh-123), is an efficient tumor photosensitizer for Argon laser treatment of human cancer cells both in vitro and in tumors grown as xenografts in athymic mice. To demonstrate the photodynamic mechanism of action of this reaction, the intracellular role of oxygen and temperature changes in treated cells have to be defined. In the current study, a large panel of human tumor cell lines of diverse histologic origin were tested for in vitro sensitivity to Rh-123 and the Argon laser (514.5 nm) in oxygen, deuterium oxide (D2O), and nitrogen (N2) environment. Tumor cells in suspension were first sensitized to Rh-123 (1 or 20 micrograms/ml for 1 hour), cooled on ice to 4 degrees C, and then exposed to the Argon laser (delta T = 14 +/- 1 degree C). Cell proliferation measured by (3H)-thymidine uptake 24 hours after sensitization with Rh-123 and laser treatment was significantly decreased in tumor cells kept in oxygen and D2O atmospheres. No decrease in DNA synthesis was seen in Rh-123 and laser treated cells kept in an N2 environment. Control tumor cells treated with Rh-123 or the Argon laser separately did not show any decreased (3H)-thymidine uptake in oxygen, D2O or N2 environment. These results provide evidence of a photodynamic process since Rh-123 sensitization and Argon laser activation occur at nonthermal levels of energy and are oxygen dependent. The high effectiveness of this technique of photodynamic therapy with the Argon laser, and low toxicity of Rh-123 could make its clinical use very attractive for the treatment of superficial malignancies.

  16. Application of argon laser LAK-1 for therapy in selected blood vessel diseases

    Science.gov (United States)

    Szymanczyk, Jacek; Golebiowska, Aleksandra; Michalska, I.; Nowakowski, Wlodzimierz

    1995-03-01

    Argon laser was applied in 172 patients with various vascular disorders and epidermal nevi. The best therapeutical results were obtained in facial telangiectasia and in cavernous hemangiomas, in which there was a complete or almost complete regression. In capillary facial hemangiomas in 49 patients (79%) clearing of 50% to 75% was obtained, and in epidermal nevi the full regression was in 4 (44%) of the cases, and 50% regression in 4 (44%). In telangiectasia of the lower limbs the results were not satisfactory. We stress that cavernous, and capillary hemangiomas, as well as facial telangiectasia are an indication for the argon laser therapy.

  17. Efficacy of anti-VEGF and laser photocoagulation in the treatment of visual impairment due to diabetic macular edema: a systematic review and network meta-analysis.

    Directory of Open Access Journals (Sweden)

    Stephane Régnier

    Full Text Available Compare the efficacy of ranibizumab, aflibercept, laser, and sham in the first-line treatment of diabetic macular edema (DME to inform technology assessments such as those conducted by the UK National Institute for Health and Care Excellence (NICE.MEDLINE, Embase, Cochrane Library, congress abstracts, ClinicalTrials.gov registry and Novartis data on file.Studies reporting 6- or 12-month results of randomized controlled trials (RCTs evaluating at least two of ranibizumab 0.5 mg pro re nata, aflibercept 2.0 mg bi-monthly, laser photocoagulation or sham. Study quality was assessed based on likelihood of bias in selection, attrition, detection and performance.Improvement in best-corrected visual acuity (BCVA measured as the proportion of patients gaining ≥10 letters on the Early Treatment Diabetic Retinopathy Study scale. The outcome was chosen following acceptance by NICE of a Markov model with 10-letter health states in the assessment of ranibizumab for DME.Bayesian network meta-analyses with fixed and random effects adjusted for differences in baseline BCVA or central retinal thickness.The analysis included 1,978 patients from eight RCTs. The random effects model adjusting for baseline BCVA was the best model based on total residual. The efficacy of ranibizumab was numerically, but not statistically, superior to aflibercept (odds ratio [OR] 1.59; 95% credible interval [CrI], 0.61-5.37. Ranibizumab and aflibercept were statistically superior to laser monotherapy with ORs of 5.50 (2.73-13.16 and 3.45 (1.62-6.84 respectively. The probability that ranibizumab is the most efficacious treatment was 73% compared with 14% for aflibercept, 12% for ranibizumab plus laser, and 0% for laser.Three of the eight RCTs included are not yet published. The models did not adjust for all potential effect modifiers.Ranibizumab was non-significantly superior to aflibercept and both anti-VEGF therapies had statistically superior efficacy to laser.

  18. Laser in ophthalmology. Laser i oftalmologien

    Energy Technology Data Exchange (ETDEWEB)

    Syrdalen, P. (Rikshospitalet, Oslo (Norway))

    1991-09-01

    The article presents a brief history of the use of laser in ophthalmology in Norway, from the introduction of the first argon-photocoalulator in 1972 to the excimer laser in 1990. The argon-photocoagulator is in daily us in all Eye Departments in Norway and the main group of patients treated are those with diabetic retionopathy. Glaucoma has been treated with argon-laser with good results for the last ten years. YAG-laser, introduced in Norway in 1985, is used to treat secondary cataracts which occur after extracapsular cataract extractions and implantation of artificial lenses. In 1990, the excimer laser was introduced for refractive surgery (myopia, astigmatism). 4 refs., 6 figs., 1 tab.

  19. Nitrogen/argon diluted acetylene and ethylene blue flames under infrared CO2 laser irradiation

    OpenAIRE

    Pikhitsa, Peter V.; Daegyu Kim; Mansoo Choi

    2011-01-01

    We investigated changes in emission spectra from nitrogen/argon diluted laminar diffusion acetylene and ethylene blue flames irradiated by a powerful cw infrared CO2 laser. The changes in the radical emission bands can be interpreted as an indication of laser-induced decomposition of ethylene (for laser absorbing C2H4 fuel) and of laser-absorbing intermediates (for non-absorbing C2H2 fuel). The results indicate that released active hydrogen plays an important role in addition/abstraction reac...

  20. Nitrogen/argon diluted acetylene and ethylene blue flames under infrared CO2 laser irradiation

    Directory of Open Access Journals (Sweden)

    Peter V. Pikhitsa

    2011-09-01

    Full Text Available We investigated changes in emission spectra from nitrogen/argon diluted laminar diffusion acetylene and ethylene blue flames irradiated by a powerful cw infrared CO2 laser. The changes in the radical emission bands can be interpreted as an indication of laser-induced decomposition of ethylene (for laser absorbing C2H4 fuel and of laser-absorbing intermediates (for non-absorbing C2H2 fuel. The results indicate that released active hydrogen plays an important role in addition/abstraction reactions without any participation of oxygen.

  1. 577nm阈下微脉冲激光治疗黄斑水肿时光凝斑的影像学观察%Image observation of laser spots from subthreshold micropulse laser (577nm) photocoagulation for macular edema

    Institute of Scientific and Technical Information of China (English)

    侯军军; 闰爱珍; 袁红; 贾亚丁

    2012-01-01

    目的 用多波长照相技术(F-10)观察577 nm阈下微脉冲激光光凝治疗黄斑水肿时光凝斑的形态学改变.方法 前瞻性系列病例研究.黄斑水肿患者17例(19眼)纳入研究.所有患者均经眼底荧光素血管造影(FFA)及光学相干断层扫描(OCT)检查确诊,其中,糖尿病黄斑水肿患者8例(10眼),视网膜中央静脉阻塞引起的黄斑水肿患者5例(5眼),视网膜分支静脉阻塞引起的黄斑水肿患者4例(4眼).首先在传统连续波激光下对患眼进行阈能量P测定,然后在F-10的retro mode模式检测下对这19眼进行阈下微脉冲光凝测试及治疗,微脉冲激光所用能量的调整参照阈能量P.留取患眼光凝前后眼底彩照及自发荧光成像,并随访观察术后1个月患眼中心凹厚度(CMT)及最佳矫正视力(BCVA)变化.分别采用配对t检验、配对秩和检验对数据进行分析.结果 术后即刻retro mode成像中,6眼在122.4%P能量下出现光凝斑;8眼在153.1%P能量下出现光凝斑;5眼在183.7%P能量下出现光凝斑.术后即刻在眼底彩照及自发荧光成像下光凝区未发生改变.术后1个月患眼CMT较术前明显降低,差异有统计学意义(t=4.238,P<0.01),BCVA与术前相比无明显变化.结论 Retro mode 成像可检测到阈下微脉冲激光光凝产生的不可见光凝斑,在治疗时可用于指导光凝能量大小的选择.%Objective To observe the laser spots created by subthreshold micropulse laser (577 nm) photocoagulation for macular edema with a multi-wavelength photographic technique (F-10).Methods It was a prospective case-series study.Seventeen patients (19 eyes) with macular edema diagnosed by fundus fluorescein angiography (FFA) and optical coherence tomography (OCT) were included.Eight patients (10 eyes) were diagnosed with diabetic macular edema (DME),5 patients (5 eyes) with macular edema attributable to central retinal vein occlusion (CRVO) and 4 patients (4 eyes) with macular edema

  2. Transpupillary Argon Laser Cyclophotocoagulation in a Refractory Traumatic Glaucoma Patient with Aphakia and Aniridia

    Directory of Open Access Journals (Sweden)

    Umut Duygu Uzunel

    2016-01-01

    Full Text Available We present a case of transpupillary argon laser cyclophotocoagulation (TALC in a patient with traumatic aniridia and aphakia secondary to blunt trauma who had previous bilateral trabeculectomy. Four months after the trauma the patient’s intraocular pressure (IOP rose to 35 mmHg despite topical antiglaucomatous medication. Inferior 180 degrees cyclophotocoagulation was performed with transpupillary argon laser in the first session and his IOP fell to values of 12-17 mmHg. Twelve weeks after TALC, his IOP rose to 22 mmHg and we had to apply TALC to the residual ciliary processes. Seven months later his IOP was 13 mmHg with topical dorzolamide/timolol and latanoprost administration. TALC may be an effective treatment alternative for lowering IOP in patients with visible ciliary processes who do not respond to conventional medical or laser treatment.

  3. Laser Argon-40-Argon-39 Age Studies of Dar Al Gani 262 Lunar Meteorite

    Science.gov (United States)

    Fernandes, V. A.; Burgess, R.; Turner, G.

    1999-01-01

    The lunar meteorite Dar al Gani 262 (DAG 262) was found in the Sahara Desert in Libya on March 23,1997. This was the first lunar meteorite found in a desert and is the thirteenth lunar meteorite discovered. DAG 262 is a polymict anorthositic lunar highland breccia. The Ar-40-Ar-39 dating technique has been applied to DAG 262 in an attempt to determine the crystallization age and shock events experienced by this meteorite. Previous studies have indicated that this meteorite may have suffered up to four shock events. Due to the brecciated nature of the rock and the likelihood of multiple shock events, a laser-probe technique has been used to analyze individual components (minerals and clasts) of the meteorite. The sample supplied to us ( about 1.5 g) shows two distinct clast types (1) feldspathic and (2) basaltic, the latter not having been previously described. Plagioclases show fractures and undulatory extinction as the result of shock events. The feldspathic clast has small, round low-Ca pyroxenes distributed within it. Electron-microprobe analyses of feldspar and pyroxene are given. The bulk composition as determined by suggests that the source of this clast is the ferroan-anorthositic suite. The basaltic clast shows a very fine intergranular texture with some larger plagioclase grains. The two clasts are separated by a melt-glass matrix that contains plagioclase with the same chemical composition as those plagioclases within the feldspathic clast. A devitrified mafic-glass spherule of - 150 mm diameter was identified within the matrix as well as other small fragments of possible glass spheres. Some dendritic veins can be observed on the outer part of the section, which formed after breccia lithification. Two laser Ar-40-Ar-39 experiments are being carried out: (1) infrared laser-stepped heating of feldspathic fragments that have been separated from the meteorite; and (2) ultraviolet laser spot fusion (50 micron) of a slice of meteorite (about 1.0 x 0.5 cm

  4. Study of the fluctuations of ionized argon laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Butkevich, V.I.; Privalov, V.E.; Skvortsova, G.V.

    1986-11-01

    The aim of the present work was to study the fluctuations of the radiated power of a common domestic laser LGN-404A, their relation to disturbances in the discharge current, and the assurance of higher stability of the output power of this laser. A diagram of the experimental apparatus is given. Study of oscillations in the discharge current was conducted, as well as the output power fluctuations. The studies conducted permit the development of a series of measures and instruments which guarantee at least an order of magnitude reduction of the instability level of commercially manufactured LGN-404A laser devices.

  5. The effect of chirped intense femtosecond laser pulses on the Argon cluster

    CERN Document Server

    Ghaforyan, H; Irani, E

    2016-01-01

    The interaction of intense femtosecond laser pulses with atomic Argon clusters has been investigated by using nano-plasma model. Based on the dynamic simulations, ionization process, heating and expansion of a cluster after irradiation by femtosecond laser pulses at intensities up to 2*1017 Wcm-2 are studied. The analytical calculation provides ionization ratefor different mechanisms and time evolution of the density of electrons for different pulse shapes. In this approach the strong dependence of laser intensity, pulse duration and laser shape on the electron energy, the electron density and the cluster size are presented using the intense chirped laser pulses. Based on the presented theoretical modifications, the effect of chirped laser pulse on the complex dynamical process of the interaction is studied. It is found that the energy of electrons and the radius of cluster for the negatively chirped pulsesare improved up to 20% in comparison to the unchirped and positively chirped pulses.

  6. Laser-Assisted Elastic Electron Scattering from Argon

    Institute of Scientific and Technical Information of China (English)

    HU Qiu-Bo; SUN Jin-Feng

    2009-01-01

    The second Born approximation (SBA) theory is applied to the study of electron-atom scattering in the presence of a CO2 laser field. The absolute differential cross sections of e-At scattering are calculated with multiphoton exchange in two special scattering geometries G1 (for small-angle scattering) and G2. For geometry G1, compared with the results of two different model potentials for electron elastic scattering by atoms, it is found that electronatom polarization potential plays an important role in laser-assisted electron-atom scattering. Some calculational results in geometries G2 are given. Our results are found to be better than other theoretical results as compared with the experimental data in geometries G1 and G2.

  7. 相干光断层扫描对532 nm激光治疗糖尿病黄斑水肿的疗效观察%Observation of optical coherence tomography on 532nm laser photocoagulation in the treatment of diabetic macular edema

    Institute of Scientific and Technical Information of China (English)

    潘颖喆; 高丰; 王慧; 殷晖

    2011-01-01

    Objective To observe the clinical effect of 532nm laser photocoagulation therapy on diabetic macular edema with optical coherence tomography. Methods 46 continuous patients ( 61 eyes ) with clinically significant diabetic macula edema were treated by 532nm laser photocoagulation. The retinal thickness and the volume of central fovea of macula were detected by optical coherence tomography in pre-photocoagulation and post-photocoagulation after 3 months. These data and the visual acuity were analyzed statistically. Results The visual acuity in 41 eyes improved and 17 eyes unchanged after 532 nm photocoagulation. The retinal thickness and the volume of central fovea of macula in pre-photocoagulation and post-photocoagulation after 3 months were 354.7 ± 93.2 μm/8.32 ± 0.53 mm3 and 203.5 ± 49.6 μm/7.24 ±0.41 mm3 respectively. Statistically, the difference in pre-photocoagulation and post-photocoagulation was significant. Conclusion 532nm laser photocoagulation is an effective treatment for diabetic macular edema. The change of retinal thickness and the volume can be measured exactly with optical coherence tomography pre- and post-photocoagulation, and thus the accurate effect of 532nm laser photocoagulation can be evaluated exactly.%目的 评价使用相干光断层扫描(OCT)对532 nm激光治疗糖尿病黄斑水肿的疗效进行观察的有效性.方法 对糖尿病性有临床意义的黄斑部水肿病例46例(61只眼),给予532 nm激光黄斑格栅样光凝、局灶光凝以及全视网膜光凝,在治疗前、治疗后3个月分别进行裸眼视力、眼底照相、荧光素眼底血管造影及OCT黄斑区视网膜厚度及视网膜容积等检查.比较光凝前后黄斑区视网膜厚度和视网膜容积的变化.结果 在46例(61只眼)中,41只眼视力提高,17只眼不变,所有患者荧光素眼底血管造影显示黄斑区荧光渗漏不同程度减轻或消失,OCT显示光凝治疗前黄斑中心凹视网膜神经上皮厚度为(354.7±93

  8. The effect of argon laser irradiation on demineralization resistance of human enamel adjacent to orthodontic brackets: an in vitro study.

    Science.gov (United States)

    Noel, Lloyd; Rebellato, Joe; Sheats, Rose D

    2003-06-01

    Argon lasers, because of their significant timesavings over conventional curing lights, have been investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel, which is of great interest in orthodontics. A two-part in vitro study on 86 human posterior teeth was conducted to determine the effects of a five-second argon laser exposure on shear bond strength and to evaluate the effects of a five- and 10-second argon laser exposure (250 mW) on demineralization of enamel surrounding orthodontic brackets after exposure to an artificial caries bath. Brackets cured with the argon laser for five seconds yielded mean bond strengths similar to those attained with a 40-second conventional light-cured control (n = 13 per group, 20.4 vs 17.8 MPa). Brackets cured with the argon laser for 10 seconds resulted in significantly lower mean lesion depth when compared with a visible light control (n = 20 per group, 107.8 vs 137.2 microm, P = .038). There were no statistically significant differences in lesion depth between the five-second argon laser and the visible light control groups. Overall, there was a 15% and 22% reduction in lesion depths for the five- and 10-second group, respectively. Poor correlations were found between the clinical appearance of decalcifications and their lesion depth. Argon lasers used for bonding orthodontic brackets would save a significant amount of chair time while possibly conferring demineralization resistance upon the enamel. PMID:12828433

  9. Estudo do tratamento do edema macular difuso do diabético com triancinolona intravítrea e fotocoagulação Use of intravitreal triamcinolone and laser photocoagulation for the treatment of diffuse diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Fábio Petersen Saraiva

    2008-08-01

    Full Text Available OBJETIVO: Avaliar a eficácia do uso intravítreo da triancinolona acetonida associada a fotocoagulação com laser no tratamento do edema macular difuso diabético. Comparar esta associação terapêutica com o uso isolado de cada tratamento. MÉTODOS: Após controle clínico sistêmico, trinta pacientes portadores de edema macular difuso diabético foram divididos em 3 grupos de tratamento: (1 fotocoagulação macular em grade com laser de argônio; (2 aplicação intravítrea de 4 mg de triancinolona acetonida; (3 associação dos itens anteriores. O seguimento foi realizado em intervalos predeterminados de um dia, uma semana e mensalmente, até completar 6 meses. Foram analisados os parâmetros: acuidade visual corrigida LogMAR, espessura macular central, volume macular total e pressão intra-ocular. RESULTADOS: A fotocoagulação com laser não reduziu de forma estatisticamente significativa a espessura macular central e o volume macular total. Esta redução foi significativa e estatisticamente semelhante nos outros dois grupos. Todos os grupos apresentaram melhora da acuidade visual, entretanto, o grupo que recebeu a associação do laser com a triancinolona intravítrea obteve maior porcentagem de pacientes com ganho de 10 ou mais letras de visão. CONCLUSÃO: O uso simultâneo da fotocoagulação com a triancinolona intravítrea pode ser considerado uma opção terapêutica para o edema macular difuso diabético.PURPOSE: To assess the efficacy of intravitreal use of triamcinolone acetonide combined with laser photocoagulation for the treatment of diffuse diabetic macular edema and to compare it with the separate use of each treatment. METHODS: After systemic clinical control, thirty patients with diffuse diabetic macular edema were divided into 3 treatment groups: (1 macular grid photocoagulation; (2 intravitreal injection of 4 mg of triamcinolone acetonide; (3 combination of the two previous therapies. Follow-up was scheduled at

  10. 21 CFR 886.4690 - Ophthalmic photocoagulator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic photocoagulator. 886.4690 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4690 Ophthalmic photocoagulator. (a) Identification. An ophthalmic photocoagulator is an AC-powered device intended to use the energy from an...

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

    Science.gov (United States)

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

    2015-11-01

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

  12. Argon laser iridoplasty : A primary mode of therapy in primary angle closure glaucoma

    Directory of Open Access Journals (Sweden)

    Agarwal H

    1991-01-01

    Full Text Available Argon laser iridoplasty was performed in 40 eyes of 33 patients of primary angle closure glaucoma. There were 12 male and 21 female patients. The mean ages of the male and female patients were 51 years and 48.4 years respectively. Forty eyes were divided into two groups. Group I consisted of ten eyes of subacute angle closure glaucoma and group II included thirty eyes of chronic angle closure glaucoma. Argon laser iridoplasty was performed with Coherent 9000 model using laser settings of spot size 200 micron, duration 0.2 second and power 0.7 watt. A total of 80 spots were applied over 360 degree circumference. The intraocular pressure control (below 22 mm Hg was achieved after iridoplasty in all the eyes (100% in group I, where as in group II the intraocular pressure was controlled in 70% eyes. The follow up period varied from 3 months to one year with a mean of eight months. The success rate with iridoplasty was directly related to the extent of peripheral anterior synechiae, optic disc cupping and presence of visual field changes.

  13. Effects of laser photocoagulation on serum angiopoietin-1, angiopoietin-2, angiopoietin-1/angiopoietin-2 ratio, and soluble angiopoietin receptor Tie-2 levels in type 2 diabetic patients with proliferative diabetic retinopathy

    Institute of Scientific and Technical Information of China (English)

    Qiao-Ying; You; Fu-Yuan; Zhuge; Qi-Qian; Zhu; Xu-Wei; Si

    2014-01-01

    ·AIM: To determine the effects of laser photocoagulation on serum levels of angiopoietin-1(Ang-1),angiopoietin-2(Ang-2), soluble angiopoietin receptor Tie-2(Tie-2), Ang-1/Ang-2 ratio and vascular endothelial growth factor(VEGF) in patients with type 2diabetes mellitus(T2DM) and proliferative diabetic retinopathy(PDR). We also explored the role of the Ang/Tie system in PDR.·METHODS:Totally 160patientswithT2 DM, including50 patients with non-diabetic retinopathy(NDR), 58 patients with non-proliferative diabetic retinopathy(NPDR), and52 patients with PDR were enrolled in this study. Serum Ang-1, Ang-2, Tie-2 receptor and VEGF levels were measured using enzyme-linked immunosorbent assays for all patients and were repeated in 26 patients who underwent laser photocoagulation two months after the procedure.·RESULTS:ThemedianlevelsofAng-2andVEGFinserum were significantly higher in the NPDR group(4.23 ng/mL and 303.2 pg/mL, respectively) compared to the NDR group(2.67 ng/mL and 159.8 pg/mL, respectively, P <0.01), with the highest level in the PDR group(6.26 ng/mL and531.2 pg/mL, respectively, P <0.01). The median level of Ang-1 was significantly higher in the NPDR group(10.77ng/mL) compared to the NDR group(9.31 ng/mL) and the PDR groups(9.54 ng/mL)(P <0.05), while no difference was observed between the PDR and NDR groups. Ang-1/Ang-2 ratio of PDR group was lowest in three groups(1.49 vs 2.69 and 2.90, both P <0.01). The median level of Tie-2was not significantly different among three groups(P >0.05).Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups(both P <0.05). Among the 26 patients who underwent laser photocoagulation, serum Ang-2 and VEGF levels significantly decreased(both P <0.05), whereas serum Ang-1 level and Ang-1/Ang-2ratio were weakly increased(P >0.05). The median levels of Ang-2 and VEGF in serum were highest in PDR group,however, Ang-1/Ang-2 ratio of PDR group was lowest in three groups.·CONCLUSION: Laser photocoagulation can

  14. Demonstration of a neonlike argon soft-x-ray laser with a picosecond-laser-irradiated gas puff target.

    Science.gov (United States)

    Fiedorowicz, H; Bartnik, A; Dunn, J; Smith, R F; Hunter, J; Nilsen, J; Osterheld, A L; Shlyaptsev, V N

    2001-09-15

    We demonstrate a neonlike argon-ion x-ray laser, using a short-pulse laser-irradiated gas puff target. The gas puff target was formed by pulsed injection of gas from a high-pressure solenoid valve through a nozzle in the form of a narrow slit and irradiated with a combination of long, 600-ps and short, 6-ps high-power laser pulses with a total of 10 J of energy in a traveling-wave excitation scheme. Lasing was observed on the 3p (1)S(0)?3s (1)P(1) transition at 46.9 nm and the 3d (1)P(1)?3p (1)P(1) transition at 45.1 nm. A gain of 11 cm(-1) was measured on these transitions for targets up to 0.9 cm long. PMID:18049619

  15. Volume Measurements of Laser-generated Pits for In Situ Geochronology using KArLE (Potassium-Argon Laser Experiment)

    Science.gov (United States)

    French, R. A.; Cohen, B. A.; Miller, J. S.

    2014-01-01

    The Potassium-Argon Laser Experiment( KArLE), is composed of two main instruments: a spectrometer as part of the Laser-Induced Breakdown Spectroscopy (LIBS) method and a Mass Spectrometer (MS). The LIBS laser ablates a sample and creates a plasma cloud, generating a pit in the sample. The LIBS plasma is measured for K abundance in weight percent and the released gas is measured using the MS, which calculates Ar abundance in mols. To relate the K and Ar measurements, total mass of the ablated sample is needed but can be difficult to directly measure. Instead, density and volume are used to calculate mass, where density is calculated based on the elemental composition of the rock (from the emission spectrum) and volume is determined by pit morphology. This study aims to reduce the uncertainty for KArLE by analyzing pit volume relationships in several analog materials and comparing methods of pit volume measurements and their associated uncertainties.

  16. THz wave emission from argon in two-color laser field

    Institute of Scientific and Technical Information of China (English)

    杜玲玲; 赵松峰; 周效信; 赵增秀

    2015-01-01

    Terahertz (THz) wave emission from argon atom in a two-color laser pulses is studied numerically by solving the one-dimensional (1D) time-dependent Schr ¨odinger equation. The THz spectra we obtained include both discontinuous and continuum ones. By using the special basis functions that we previously proposed, our analysis points out that the discontinuous and continuum parts are contributed by bound–bound and continuum–continuum transition of atomic energy levels. Although the atomic wave function is strongly dressed during the interaction with laser fields, our identification for the discontinuous part of the THz wave shows that the transition between highly excited bound states can still be well described by the field-free basis function in the tunneling ionization regime.

  17. The Potassium-Argon Laser Experiment (KArLE): In Situ Geochronology for Planetary Robotic Missions

    Science.gov (United States)

    Cohen, Barbara

    2016-01-01

    The Potassium (K) - Argon (Ar) Laser Experiment (KArLE) will make in situ noble-gas geochronology measurements aboard planetary robotic landers and roverss. Laser-Induced Breakdown Spectroscopy (LIBS) is used to measure the K abun-dance in a sample and to release its noble gases; the evolved Ar is measured by mass spectrometry (MS); and rela-tive K content is related to absolute Ar abundance by sample mass, determined by optical measurement of the ablated volume. KArLE measures a whole-rock K-Ar age to 10% or better for rocks 2 Ga or older, sufficient to resolve the absolute age of many planetary samples. The LIBS-MS approach is attractive because the analytical components have been flight proven, do not require further technical development, and provide complementary measurements as well as in situ geochronology.

  18. Biostimulation of human carcinoma cells with the argon laser: a previously unreported potential iatrogenic effect of lasers

    Energy Technology Data Exchange (ETDEWEB)

    Castro, D.J.; Saxton, R.E.; Fetterman, H.R.; Castro, D.J.; Ward, P.H.

    1988-01-01

    The human squamous carcinoma cell line P3 was subjected to treatment with a single mode argon laser at 514.5 nm. The temperature and energy levels delivered to the target cells were determined by a reproducible method of dosimetry. At energy levels between 860 to 990 J/cm2 and a corresponding temperature of 39 +/- 1 degrees C, a significant delayed stimulation in DNA synthesis was noted after 24 hours, but the cells remained viable. However, at energy levels and temperatures higher or equal to 1100 J/cm2 (41 degrees C), an immediate suppression of DNA synthesis was accompanied by nonviability of the P3 carcinoma cells. These results indicate that the argon laser has potential for selective biostimulation on carcinoma cell duplication at the specific non-thermal range of 39 +/- 1 degrees C. Similar effects were not observed when the P3 carcinoma cells were heated to this same temperature using a standard heat bath. This phenomenon appears to represent a previously undescribed potential iatrogenic effect of the monochromatic laser beam in the treatment of cancer.

  19. Argon green-Nd: YAG dual laser posterior hyaloidotomy: An innovative approach toward treatment of premacular hemorrhage

    Directory of Open Access Journals (Sweden)

    Ashish Sharma

    2013-01-01

    Full Text Available Background: Neodymium: YAG (Nd: YAG laser and argon laser has been used to treat premacular hemorrhage either alone or rarely in combination. Materials and Methods: We describe a new technique of treating premacular hemorrhage by performing hyaloidotomy using a combination of argon green-Nd: YAG laser. We utilized subthreshold energy levels of Nd: YAG laser of 2.0 mJ as compared to the normal recommendation of 3.6-50 mJ. Results and Conclusions: This technique is easy, effective, and safe to manage premacular hemorrhage. The principle behind this combined laser treatment was to make the internal limiting membrane (ILM taut by initial exposure to argon green laser, which allowed us to employ the subthreshold energy levels of Nd: YAG laser. We would like to assess the role of this combined treatment modality in comparison to other modalities, including solitary laser therapy in the management of premacular hemorrhage by performing a prospective, randomized long-term study.

  20. 中药联合视网膜激光光凝术治疗外伤性黄斑出血临床研究%Clinical Study of Traumatic Macula Lutea Hemorrhage by TCM Combine with Retinal Laser Photocoagulation

    Institute of Scientific and Technical Information of China (English)

    姚学云

    2015-01-01

    目的:观察中药联合视网膜激光光凝术治疗外伤性黄斑出血的临床疗效。方法:64例确诊为外伤性黄斑出血患者随机分为对照组和治疗组各32例,对照组行视网膜激光光凝术治疗,治疗组在对照组基础上加用中药治疗。两组均以7 d为1个疗程,1个疗程后比较两组视力疗效、黄斑出血疗效和黄斑区荧光素渗漏疗效。结果:治疗组视力有效率为93.75%,对照组有效率为78.13%,两组有效率比较,差异有统计学意义( P<0.05);治疗组黄斑出血有效率为78.13%,对照组黄斑出血有效率为62.50%,两组有效率比较,差异有统计学意义(P<0.05);治疗组黄斑区荧光素渗漏有效率为87.5%,对照组黄斑区荧光素渗漏有效率为71.88%,两组有效率比较,差异有统计学意义( P<0.05)。结论:中药联合视网膜激光光凝术治疗外伤性黄斑出血疗效显著。%Objective:To observe the clinical effects of traumatic macula lutea hemorrhage by TCM combine with retinal laser photocoag-ulation. Methods:64 patients divided into control group and treatment group,each group is 32 cases. The control group was given retinal laser photocoagulation. The treatment group was based on the the control group with TCM. 1course is 7days,after the course,compare the curative effect of eyesight,macula lutea hemorrhage and fluorescein leakage in macular region. Results:The eyesight effective rate in the treatment group is 93. 75%,while in the control group is 78. 13%,compare with the effective rate between the two groups were sta-tistically significant(P<0. 05);In the treatment group,the effective rate of macula lutea hemorrhage is 78. 13%,while the control group is 62.50%,compare with the effective rate between the two groups were statistically significant(P<0. 05);In the treatment group,the effective rate of macular region fluorescein leakage is 87. 5%,while in the control group is 71. 88%,compare with

  1. Studies in Above- and Below-Threshold Harmonics in Argon with an Infrared Femtosecond Laser

    Science.gov (United States)

    Chew, Andrew; Yin, Yanchun; Li, Jie; Ren, Xiaoming; Cunningham, Eric; Wu, Yi; Chang, Zenghu

    2016-05-01

    We investigate and compare the above- and below-threshold harmonics in Argon gas using our recently-developed 1 kHz, two-cycle (11.4 fs), 3mJ, and carrier-envelope-phase(CEP)-stable laser at 1.6 μm. Such ultraviolet pulses can serve as pump or probe for studying dynamics in atoms and molecules. Unlike high harmonics with photon energy well above the ionization potential, the mechanism for generating harmonics near the ionization threshold is still under intense investigation. Previous work by Chini et al. on below-threshold harmonics was done using a 0.8 μm few-cycle Ti:Sapphire spectrally-broadened source with energy up to 300 μJ. It has been predicted by theory that free-free transitions dominate the below threshold harmonic generation as the laser wavelength increase from near infrared to mid-infrared. We are therefore interested in investigating how using a longer wavelength laser might lead to changes to the behavior of below-threshold harmonics when we vary various parameters. We report the π-periodity CEP dependence and ellipticity dependence of the above- and below-threshold harmonics. This material was based on work supported by National Science Foundation (1068604), Army Research Office (W911NF-14-1-0383), Air Force Office of Scientific Research (FA9550-15-1-0037) and the DARPA PULSE program by a Grant from AMRDEC (W31P4Q1310017).

  2. Comparison of the argon tunable dye laser with the flashlamp pulsed dye laser in treatment of facial telangiectasia

    Science.gov (United States)

    Broska, Pamela; Martinho, Elena; Goodman, Matthew M.

    1992-06-01

    A prospective, side-by-side comparison study of two different lasers for the treatment of solar- induced telangiectasia was carried out in 14 patients at the Beckman Laser Institute and Medical Clinic. The argon tunable dye laser (Coherent, Palo Alto, Calif.) was used in the method modified from Orenstein and Nelson to completely treat discrete telangiectasias on one cheek. Specifically, the argon tunable dye laser (ATDL) was set at 0.7 - 0.8 watts, 585 nm wavelength, shutter-pulsed at 0.1 second duration with a spot size of 0.1 mm, and individual vessels were 'traced out' with 4X loupe magnification. Each patient's opposite cheek was then treated in the standard fashion with the flashlamp pulsed dye laser (Candela, Natick, Mass.) using a technique similar to Polla's et al. Specifically, the flashlamp pulsed dye laser (FPDL) was set at 585 nm wavelength, pulsed mode of 450 microseconds pulse duration, spot size of 5 mm, overlapping 10 - 20%, with power densities of 5.5 to 6.5 joules/cm2. All patients had symmetrical cheek telangiectasias of several years' duration. Patients were treated on day 0, and examined on weeks 2, 4, and 6. Photos were taken at each visit, and evaluation was done by questionnaire and direct observation, as well as by photographic slides later projected to an impartial panel. Final evaluation by the panel at week 6 showed 11/14 patients with excellent results (75 - 100% clearing) at sites treated with the FPDL, compared with 4/14 with the ATDL. In contrast, 4/14 FPDL sites were graded as fair to minimal improvement, and 9/14 as fair for the ATDL. The patients' self-evaluations graded the final results very similar to that of the panel. Most patients were bothered by the ecchymosis and hyperpigmentation associated with the FPDL, resulting in less than 50% of the patients preferring the FPDL despite its more impressive results. We conclude that the final results favor the FPDL over the ATDL for treatments of facial telangiectasia. However, non

  3. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    Energy Technology Data Exchange (ETDEWEB)

    Makito, K.; Shin, J.-H. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka (Japan); Zhidkov, A.; Hosokai, T.; Masuda, S. [Photon Pioneers Center, Osaka University, 2-8, Yamadaoka, Suita, Osaka (Japan); Japan Science and Technology Agency (JST), CREST, 2-8 Yamadaoka, Suita, Osaka (Japan); Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka (Japan); Photon Pioneers Center, Osaka University, 2-8, Yamadaoka, Suita, Osaka (Japan); Japan Science and Technology Agency (JST), CREST, 2-8 Yamadaoka, Suita, Osaka (Japan)

    2012-10-15

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of {approx}3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  4. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    Science.gov (United States)

    Makito, K.; Zhidkov, A.; Hosokai, T.; Shin, J.-H.; Masuda, S.; Kodama, R.

    2012-10-01

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of ˜3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  5. Measurement of solubility and water sorption of dental nanocomposites light cured by argon laser.

    Science.gov (United States)

    Mirsasaani, Seyed Shahabeddin; Ghomi, Farhad; Hemati, Mehran; Tavasoli, Tina

    2013-03-01

    Different parameters used for photoactivation process and also composition provide changes in the properties of dental composites. In the present work the effect of different power density of argon laser and filler loading on solubility (SL) and water sorption (WS) of light-cure dental nanocomposites was studied. The resin of nanocomposites was prepared by mixing bisphenol A glycol dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) with a mass ratio of 65/35. 20 wt.% and 25 wt.% of nanosilica fillers with a primary particle size of 10 nm were added to the resin. Camphorquinone (CQ) and DMAEMA were added as photoinitiator system. The nanocomposites were cured by applying the laser beam at the wavelength of 472 nm and power densities of 260 and 340 mW/cm(2) for 40 sec. Solubility and water sorption were then measured according to ISO 4049, which in our case, the maximums were 2.2% and 4.3% at 260 mW/cm(2) and 20% filler, respectively. The minimum solubility (1.2%) and water sorption (3.8%) were achieved for the composite containing 25% filler cured at 340 mW/cm(2). The results confirmed that higher power density and filler loading decreased solubility of unreacted monomers and water sorption and improved physico-mechanical properties of nanocomposites.

  6. Developement of the Potassium-Argon Laser Experiment (KArLE) for In Situ Geochronology

    Science.gov (United States)

    Cohen, Barbara A.

    2012-01-01

    Absolute dating of planetary samples is an essential tool to establish the chronology of geological events, including crystallization history, magmatic evolution, and alteration. Thus far, radiometric geochronology of planetary samples has only been accomplishable in terrestrial laboratories on samples from dedicated sample return missions and meteorites. In situ instruments to measure rock ages have been proposed, but none have yet reached TRL 6, because isotopic measurements with sufficient resolution are challenging. We have begun work under the NASA Planetary Instrument Definition and Development Program (PIDDP) to develop the Potassium (K) - Argon Laser Experiment (KArLE), a novel combination of several flight-proven components that will enable accurate KAr isochron dating of planetary rocks. KArLE will ablate a rock sample, measure the K in the plasma state using laser-induced breakdown spectroscopy (LIBS), measure the liberated Ar using quadrupole mass spectrometry (QMS), and relate the two by measuring the volume of the abated pit using a optical methods such as a vertical scanning interferometer (VSI). Our preliminary work indicates that the KArLE instrument will be capable of determining the age of several kinds of planetary samples to 100 Myr, sufficient to address a wide range of geochronology problems in planetary science. Additional benefits derive from the fact that each KArLE component achieves analyses common to most planetary surface missions.

  7. Effect of Fast Curing Lights, Argon Laser, and Plasma Arc on Bond Strengths of Orthodontic Brackets: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    M. Hashem-Hoseini

    2008-12-01

    Full Text Available Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland, the argon laser unit (Bo-5, Iran , and the plasma arc unit (Remecure 15, Belgium. The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek. After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany.Results: The mean bond strengths was 17.344 MPa (SD=4.567 for halogen 19.172 MPa(SD=6.328 for laser and 19.322 MPa (SD=4.036 for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light.

  8. In vivo argon laser vascular welding using thermal feedback: open and closed loop patency and collagen crosslinking

    Energy Technology Data Exchange (ETDEWEB)

    Small, W., LLNL

    1997-02-28

    An in vivo study of vascular welding with a fiber-delivered argon laser was conducted using a canine model. Longitudinal arteriotomies and venotomies were treated on femoral vein and artery. Laser energy was delivered to the vessel wall via a 400 {micro}m optical fiber. The surface temperature at the center of the laser spot was monitored in real time using a hollow glass optical fiber-based two-color infrared thermometer. The surface temperature was limited by either a room-temperature saline drip or direct feedback control of the laser using a mechanical shutter to alternately pass and block the laser. Acute patency was evaluated either visually (leak/no leak) or by in vivo burst pressure measurements. Biochemical assays were performed to investigate the possible laser-induced formation or destruction of enzymatically mediated covalent crosslinks between collagen molecules. Viable welds were created both with and without the use of feedback control. Tissues maintained at 50 C using feedback control had an elevated crosslink count compared to controls, while those irradiated without feedback control experienced a decrease. Differences between the volumetric heating associated with open and closed loop protocols may account for the different effects on collagen crosslinks. Covalent mechanisms may play a role in argon laser vascular fusion.

  9. Argon Partitioning Between Metal and Silicate Liquids in the Laser-Heated DAC to 25 GPa

    Science.gov (United States)

    Bouhifd, M. A.; Jephcoat, A. P.

    2003-12-01

    The accretion of the Earth from primordial material and its subsequent segregation into core and mantle are fundamental problems in terrestrial and solar system science. Many of the questions about the process, although well developed as model scenarios over the last few decades, are still open and much debated, and include, for example, whether the core is, or was, a reservoir for the noble (rare) gases. In the present study we use for the first time the laser-heated diamond-anvil cell (LHDAC) to study the Ar partitioning at high-pressure and temperature between metal and silicate liquids. Little work has been reported on noble gas partitioning at pressure since a single multi-anvil experiment to 10 GPa (Matsuda et al., 1993). We used either compacted glass powders simulating that of a model C1 chondrite and iron metal, or pure metal alloys (pure Fe, FeNiCo alloy, FeSi). Thermal insulation from the diamonds was achieved with solid argon as pressure medium. The samples were heated by a multimode YAG laser for an average of 15 minutes and temperatures were determined spectro-radiometrically with a fit to a grey-body Planck function. Samples recovered after the runs were analysed by electron microprobe with spatial resolution near 1 μ m. The argon melts by conductive heating from the molten sample dissolving into the metal/silicate melt. Preliminary results on Ar solubility at lower pressures show good agreement with data reported by White et al. (1986) for Ar solubility in sanidine (KAlSi3O8). With sanidine melt, Ar solubility increases up to around 5-6 GPa where it reaches about 2.5 wt%, and remains roughly constant to higher pressures, suggesting that a threshold concentration is reached. Similar behavior is observed for a mix of C1-chondrite composition and iron and the results imply that the solubility of Ar is intimately related to liquid structure at high pressure. We also present results on Ar solubility into pure silicate liquids of varying composition in

  10. Successful Surgical Management of Retinopathy of Prematurity Showing Rapid Progression despite Extensive Retinal Photocoagulation.

    Science.gov (United States)

    Gadkari, Salil S; Kulkarni, Sucheta R; Kamdar, Rushita R; Deshpande, Madan

    2015-01-01

    The management of retinopathy of prematurity (ROP) can be challenging in preterm babies with a gestational age oxygen therapy for respiratory distress, sepsis, neonatal jaundice). A premature infant presented with "hybrid" zone 1 disease in the right eye and aggressive posterior ROP in the left eye. Both eyes were adequately treated with laser photocoagulation; however, the eyes deteriorated and progressed to stage 4 ROP. Both eyes eventually underwent intravitreal bevacizumab followed by lens sparing vitrectomy with good anatomical and visual outcome. Anticipation of progression despite laser photocoagulation in certain clinical scenarios, frequent follow-up and timely surgical intervention is paramount. PMID:26180484

  11. Panretinal photocoagulation versus intravitreal injection retreatment pain in high-risk proliferative diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Célia Regina Farias de Araújo Lucena

    2013-02-01

    Full Text Available PURPOSE: To compare pain related to intravitreal injection and panretinal photocoagulation in the management of patients with high-risk proliferative diabetic retinopathy. METHODS: Prospective study including patients with high-risk proliferative diabetic retinopathy and no prior laser treatment randomly assigned to receive panretinal photocoagulation (PRP group or panretinal photocoagulation plus intravitreal ranibizumab (PRPplus group. In all patients, panretinal photocoagulation was administered in two sessions (weeks 0 and 2, and intravitreal ranibizumab was administered at the end of the first laser session in the PRPplus group. Retreatment was performed at weeks 16 and 32 if active new vessels were detected at fluorescein angiography. Patients in the PRPplus group received intravitreal ranibizumab and patients in the PRP group received 500-µm additional spots per quadrant of active new vessels. After the end of retreatment, a 100-degree Visual Analog Scale was used for pain score estimation. The patient was asked about the intensity of pain during the whole procedure (retinal photocoagulation session or intravitreal ranibizumab injection. Statistics for pain score comparison were performed using a non-parametric test (Wilcoxon rank sums. RESULTS: Seventeen patients from PRPplus and 14 from PRP group were evaluated for pain scores. There were no significant differences between both groups regarding gender, glycosylated hemoglobin and disease duration. Mean intravitreal injection pain (±SEM was 4.7 ± 2.1 and was significantly lower (p<0.0001 than mean panretinal photocoagulation pain (60.8 ± 7.8. Twelve out of 17 patients from the PRPplus group referred intensity pain score of zero, while the minimal score found in PRP group was found in one patient with 10.5. CONCLUSION: In patients with high-risk proliferative diabetic retinopathy who needed retreatment for persistent new vessels, there was more comfort for the patient when retreatment

  12. Recurrent pterygia--laser therapy : A preliminary report

    OpenAIRE

    Saifuddin Shabbir; Baum Klaus

    1993-01-01

    We report our experience with the use of Argon laser photocoagulation for the treatment of recurrent pterygia. In this study, 36 patients and 42 eyes with recurrent pterygia having undergone previous surgery one or more times, were subjected to laser therapy. The patients were followed up for a period of 9-12 months. The success rate was 92.8% when laser therapy was employed in recurrent pterygia which were excised once, while it was 64.2% in cases where excisions were done two ...

  13. Color center laser optogalvanic spectroscopy of lithium, barium, neon and argon Rydberg states in hollow cathode discharges

    International Nuclear Information System (INIS)

    Numerous infrared transitions between Rydberg states of neon and argon have been measured by optogalvanic spectroscopy in commercial hollow cathode lamps using a color center laser operating in the range 3600-4100 cm-1. Transitions in lithium and barium atoms sputtered from the cathodes were also detected. The generality and high sensitivity of this technique indicates potential applications for frequency calibration in the infrared, atomic and molecular spectroscopy, and plasma diagnostics. (orig.)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-12-01

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

  16. The second Born approximation of electron–argon elastic scattering in a bichromatic laser field

    Indian Academy of Sciences (India)

    Bin Zhou; Ming-Yang Zheng; Da-Yong Wen

    2012-03-01

    We study the elastic scattering of atomic argon by electron in the presence of a bichromatic laser field in the second Born approximation. The target atom is approximated by a simple screening potential and the continuum states of the impinging and emitting electrons are described as Volkov states. We evaluate the S-matrix elements numerically. The dependence of differential cross-section on the relative phase between the two laser components is presented. The results obtained in the first and second Born approximations are compared and analysed.

  17. Experimental investigation of the structure and the dynamics of nanosecond laser-induced plasma in 1-atm argon ambient gas

    Science.gov (United States)

    Ma, Qianli; Motto-Ros, Vincent; Bai, Xueshi; Yu, Jin

    2013-11-01

    We have investigated the structure and the dynamics of the plasma induced on a metallic target in 1-atm argon ambient by a nanosecond laser pulse with irradiance in the range of 10 GW/cm2. The structure is revealed to be sensitively dependent on the laser wavelength. A layered structure of different species characterizes the plasma induced by ultraviolet 355 nm pulse, while an effective mixing between the ablation vapor and the shocked ambient gas is observed with infrared 1064 nm pulse. The absorption property of the shocked gas is found to be crucial for determining the structure of the plasma.

  18. Primary argon laser trabeculoplasty in the treatment of glaucoma; A resource saving treatment. Primaer lasertrabekuloplastikk ved glaukom; En resurssparende behandling

    Energy Technology Data Exchange (ETDEWEB)

    Odberg, T. (Hamar Regional Hospital (Norway))

    1990-11-01

    During the last ten years, argon laser trabeculoplasty has been shown to be a very useful tool in the treatment of glaucoma when medical therapy has failed. In the present study laser was used as primary therapy in 27 patients with newly detected glaucoma. Pretreatment with topical timolol gave an immediate pressure drop in all eyes, and the dreaded actue pressure rise after laser treatment was avoided. Upon follow-up examination after two years, more than half the patients had an intraocular pressure below 21 mm Hg without additional therapy. Primary laser trabeculoplasty was found to be a safe and time-saving procedure. Expenses and complications associated with medical therapy are reduced. Many patients may avoid lifelong daily instillation of eye drops. 11 refs., 2 tabs.

  19. Decay of femtosecond laser-induced plasma filaments in air, nitrogen, and argon for atmospheric and subatmospheric pressures.

    Science.gov (United States)

    Aleksandrov, N L; Bodrov, S B; Tsarev, M V; Murzanev, A A; Sergeev, Yu A; Malkov, Yu A; Stepanov, A N

    2016-07-01

    The temporal evolution of a plasma channel at the trail of a self-guided femtosecond laser pulse was studied experimentally and theoretically in air, nitrogen (with an admixture of ∼3% O_{2}), and argon in a wide range of gas pressures (from 2 to 760 Torr). Measurements by means of transverse optical interferometry and pulsed terahertz scattering techniques showed that plasma density in air and nitrogen at atmospheric pressure reduces by an order of magnitude within 3-4 ns and that the decay rate decreases with decreasing pressure. The argon plasma did not decay within several nanoseconds for pressures of 50-760 Torr. We extended our theoretical model previously applied for atmospheric pressure air plasma to explain the plasma decay in the gases under study and to show that allowance for plasma channel expansion affects plasma decay at low pressures. PMID:27575227

  20. On-line experimental results of an argon gas cell-based laser ion source (KEK Isotope Separation System)

    Science.gov (United States)

    Hirayama, Y.; Watanabe, Y. X.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Jung, H. S.; Miyatake, H.; Oyaizu, M.; Kimura, S.; Mukai, M.; Kim, Y. H.; Sonoda, T.; Wada, M.; Huyse, M.; Kudryavtsev, Yu.; Van Duppen, P.

    2016-06-01

    KEK Isotope Separation System (KISS) has been developed at RIKEN to produce neutron rich isotopes with N = 126 to study the β -decay properties for application to astrophysics. The KISS is an element-selective mass-separation system which consists of an argon gas cell-based on laser ion source for atomic number selection and an ISOL mass-separation system. The argon gas cell of KISS is a key component to stop and collect the unstable nuclei produced in a multi-nucleon transfer reaction, where the isotopes of interest will be selectively ionized using laser resonance ionization. We have performed off- and on-line experiments to study the basic properties of the gas cell as well as of the KISS. We successfully extracted the laser-ionized stable 56Fe (direct implantation of a 56Fe beam into the gas cell) atoms and 198Pt (emitted from the 198Pt target by elastic scattering with a 136Xe beam) atoms from the KISS during the commissioning on-line experiments. We furthermore extracted laser-ionized unstable 199Pt atoms and confirmed that the measured half-life was in good agreement with the reported value.

  1. Towards real time speckle controlled retinal photocoagulation

    Science.gov (United States)

    Bliedtner, Katharina; Seifert, Eric; Stockmann, Leoni; Effe, Lisa; Brinkmann, Ralf

    2016-03-01

    Photocoagulation is a laser treatment widely used for the therapy of several retinal diseases. Intra- and inter-individual variations of the ocular transmission, light scattering and the retinal absorption makes it impossible to achieve a uniform effective exposure and hence a uniform damage throughout the therapy. A real-time monitoring and control of the induced damage is highly requested. Here, an approach to realize a real time optical feedback using dynamic speckle analysis is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633nm HeNe laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. It is obvious that a control system needs to determine whether the desired damage is achieved to shut down the system in a fraction of the exposure time. Here we use a fast and simple adaption of the generalized difference algorithm to analyze the speckle movements. This algorithm runs on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage. For different spot sizes (50-200 μm) and different exposure times (50-500 ms) the algorithm shows the ability to discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes. Furthermore in-vivo experiments in rabbits show the ability of the system to determine tissue changes in living tissue during coagulation.

  2. Evaluation of the hydrogen peroxide and special colorant effects under irradiation by argon and diode laser on tooth-whitening in vitro

    International Nuclear Information System (INIS)

    The aim of this study is to determine if there is any interaction between special colorant found on bleaching agents that have 35 % of hydrogen peroxide on its composition, and argon or diode laser. The first part of the study was to characterize the extrinsic stain obtained through a staining solution containing products present on the day by day diet of the general population. Thirty-two inferior human extracted incisors, free of caries and without filling material were selected for the study. The laser devices employed were Argon laser (AccuCure 3000 TM - Lasermed), wave length 488 nm, with a 200 mW/cm2 for 30 seconds in continuos mode; and diode laser (L 808 Medical Laser - Lasering do Brasil), wave length 808 ± 10 nm, with 1,6 W/cm2 for 30 seconds in continuos mode. The application mode done by a scanning movement over the buccal surface. The bleaching agents used were: Opalescence Extra (OE) - Ultradent Products USA, hydrogen peroxide 35%, gel with Carotene to convert light into heat; Pola Office (PO) - SDI - USA single doses of hydrogen peroxide; Whiteness HP (WHP) - FGM - Brasil, hydrogen peroxide 35%; Opus White (OW) - Sharplan - Israel, hydrogen peroxide 35%. The temperature rise measurement was performed with a thermocouple model 120-202-AJ, Fenwal, inserted into the pulpar chamber. The bleaching material was applied on the tooth surface with 2 mm thickness and then the irradiation was perform. The thirty two teeth were randomized in four groups, two for each laser device. The obtain data demonstrated a superior performance of the Argon laser on tooth whitening and also better results concerning the temperature rise. The alteration on tooth coloration was verified through digital spectrophotometer (Shade-Eye EX - Shofu) and quantitative analyses showed statistical differences among the groups. The bleaching results for Argon laser combined with OE and WHP were superior for the other groups. The mean variation of the temperature rise obtained Argon laser

  3. A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization

    CERN Document Server

    Rossi, B; Ereditato, A; Haug, S; Hanni, R; Hess, M; Janos, S; Juget, F; Kreslo, I; Lehmann, S; Lutz, P; Mathieu, R; Messina, M; Moser, U; Nydegger, F; Schutz, H U; Weber, M S; Zeller, M

    2009-01-01

    This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration plays an important role. Results from the first measurements are presented together with some considerations and outlook.

  4. EFFICACY AND SAFETY OF GRID PHOTOCOAGULATION IN DIFFUSE DIABETIC MACULAR EDEMA IN RURAL SETUP

    Directory of Open Access Journals (Sweden)

    Narendra P

    2014-04-01

    Full Text Available Macular edema is a common cause of visual impairment in non-proliferative diabetic retinopathy. Laser photocoagulation is considered to be the standard treatment for diabetic macular edema. This study was taken up to find out the efficacy and safety of grid photocoagulation in diffuse diabetic macular edema in our rural setup. OBJECTIVES: To assess visual improvement and document adverse effects if any in diffuse diabetic macular edema after grid photocoagulation. MATERIALS AND METHODS: In this study, 30 eyes of 17 patients with diffuse diabetic macular edema were evaluated at retina clinic at Tamaka, Kolar. The visual acuities, fundoscopic findings and adverse effects at 3 months, 6 months and 1 year checkup following laser were used in present analysis. RESULTS: After one year of follow up, visual acuity in 8 eyes (26.6% improved by one or more line, 17 (56.6% did not change and 5 (16.6% lost by one or more lines. Macular edema was found to regress in 23 (76.6% lasered eyes, found same in 6 (20%, worsened in 1 (3.3%. In our study 83.33% had positive visual acuity and 96.66% had positive fundoscopic finding. CONCLUSION: Grid photocoagulation is of benefit in maintaining vision and resolution of diffuse diabetic macular edema

  5. [Visual status in diabetic maculopathy after central photocoagulation].

    Science.gov (United States)

    Kieselbach, G; Juen, S

    1989-01-01

    Diabetic macular edema is shown to be treated successfully by central focal argon laser coagulation in most cases. Since February 1986, diabetic patients with macular edema were evaluated prospectively and treated by focal argon laser coagulation and/or grid pattern. A second group of diabetic patients with comparable macular edema and similar retinal changes was explored retrospectively. Visual acuity after treatment in relation to preoperative visual acuity was measured and statistically compared with visual acuity of the second group without laser treatment. The results show that laser treatment is important for stabilization of visual acuity but does not increase visual acuity beneath 0.2. Indications for treatment are discussed. PMID:2587022

  6. Comparative investigation of laser ablation plumes in air and argon by analysis of spectral line shapes: Insights on calibration-free laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hermann, Jörg, E-mail: hermann@lp3.univ-mrs.fr [LP3, CNRS — Aix Marseille University, 163 Av. de Luminy, 13288 Marseille (France); Gerhard, Christoph [Laboratory of Laser and Plasma Technologies, University of Applied Sciences and Arts, Von-Ossietzky-Straße 99, 37085 Göttingen (Germany); Axente, Emanuel [Laser–Surface–Plasma Interactions Laboratory, Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Măgurele (Romania); Dutouquet, Christophe [Institut National de l' Environnement Industriel et des Risques (INERIS/DRC/CARA/NOVA), Parc Technologique Alata, BP 2, 60550 Verneuil-En-Halatte (France)

    2014-10-01

    We investigate the characteristic features of plume expansion in air and argon resulting from ultraviolet laser ablation of solid matter in conditions typically applied in material analysis via laser-induced breakdown spectroscopy (LIBS). Barite crown glass is chosen as a target material for the characteristic emission spectrum suitable for plasma diagnostics. The space-integrated plasma emission spectrum recorded with an echelle spectrometer coupled to a gated detector is compared to the computed spectral radiance of a nonuniform plasma in local thermodynamic equilibrium. In particular, resonance lines of neutral sodium atoms and barium ions are observed to probe gradients of temperature and density within the plume. It is shown that laser ablation in argon leads to an almost uniform plasma whereas gradients of temperature and density are evidenced in ambient air. The discrepancy is attributed to the different physical properties of both gases leading to a stronger vapor–gas energy exchange in the case of air. However, strong gradients occur only in a thin peripheral zone, close to the vapor–gas contact front. The larger plasma core appears almost uniform. The peripheral zone of low temperature mostly contributes to the plasma emission spectrum by absorption and material analysis via calibration-free LIBS in air may ignore the nonuniform character of the plasma if only transitions of small optical thickness are considered. - Highlights: • Investigation of laser ablation plumes by analysis of spectral line shapes • Simulation of emission spectra from nonuniform laser-produced plasma • Plasma is more uniform for ablation in argon. • Plasma nonuniformity mostly affects optically thick lines. • Calibration-free LIBS may ignore gradients if optically thin lines are chosen.

  7. Current uses of ophthalmic lasers.

    OpenAIRE

    O'Neill, D; GREGSON, R; McHugh, D

    1992-01-01

    Current laser treatments are quick, relatively painless, and well tolerated. Some ophthalmic techniques can be performed only by laser while others have a lower morbidity than alternative treatments. Peripheral retinal photocoagulation and focal photocoagulation now offer greatly improved visual prognosis for diabetic patients with proliferative diabetic retinopathy or diabetic macular disease. Selected cases of macular degeneration may be treated by focal laser photocoagulation. The role of ...

  8. Detection of trace concentrations of helium and argon in gas mixtures by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    McNaghten, E.D., E-mail: Edward.McNaghten@awe.co.u [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom); Parkes, A.M.; Griffiths, B.C. [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom); Whitehouse, A.I.; Palanco, S. [Applied Photonics Ltd., Skipton, North Yorkshire, BD23 2DE (United Kingdom)

    2009-10-15

    We report what we believe to be the first demonstration of the detection of trace quantities of helium and argon in binary and ternary gas mixtures with nitrogen by laser-induced breakdown spectroscopy (LIBS). Although significant quenching of helium transitions due to collisional deactivation of excited species was observed, it was found that losses in analytical sensitivity could be minimized by increasing the laser irradiance and decreasing the pressure at which the analyses were performed. In consequence, limits of detection of parts-per-million and tens of parts-per-million and linear dynamic ranges of several orders of magnitude in analyte concentration were obtained. The results of this study suggest that LIBS may have potential applications in the detection of other noble gases at trace concentrations.

  9. On the formation of narrow bubble tracks by laser beam in argon, nitrogen and hydrogen bubble chambers

    International Nuclear Information System (INIS)

    Long bubble tracks, < 1 mm in diameter, have been produced in liquid argon and nitrogen with a nitrogen laser beam (lambda = 337 mm), offering subnanosecond pulses with small beam divergence. Bubble formation was observed over a wide range of operating conditions, including those for ordinary bubble chamber operation, with a laser pulse of 10 μJ. Typical bubble densities obtained were 4-8 bubbles/cm, with maximum densities of 20 bubbles/cm. In liquid hydrogen, tracks of 3 m visible length were observed with track diameters from 1.5 to 6 mm and bubble densities from 2 to 25 bubbles/cm. Results and applications will be discussed. (orig.)

  10. Myocardial Dose Response To Argon Laser Irradiation In Saline And Blood With Ultramicroscopical Analysis Of Myocardial Debris

    Science.gov (United States)

    Ben-Shachar, Giora; Morse, Dennis E.; Sivakoff, Mark C.; Riemenschneider, Thomas A.

    1986-01-01

    Fresh myocardial segments from fetal and adult sheep, and from newborn and adult pigs were exposed to continuous mode argon laser irradiation in saline medium. Additionally, myocardial segments from newborn pigs were exposed to laser irradiation in fresh, heparin-ized blood medium. The irradiation distance from the tip of the quartz fiber to the tissue varied between contact and 20 mm, and power output at the fiber tip varied between 1 and 8 watts. Exposure time was kept constant at 2 seconds. Tissue debris was also processed for study by scanning and transmission electron microscopy. There was no difference in myocardial tissue response between sheep and pigs, nor was there a difference in response between young and adult animals. In both saline and blood media, there was a sharp decrease in burn depth with increasing irradiation distance. With increasing irradiation distances in saline medium, burn diameter increased initially and then plateaued; while with increasing irradiation distance in blood medium, the burn diameter decreased sharply. When the fiber tip was in contact with the tissue, the diameter of burn was greater in blood than saline, while the depth of burn was similar. Filtration of the tissue bath demonstrated particles as large as 3 mm in length which were composed of deformed and coagulated whole tissue segments. Electron and scanning micrography of the bath media identified intracellular components and fragments of burst cells. In conclusion, we have found no difference in adult vs. newborn, or sheep vs. porcine myocardial response to fiberoptic argon laser irradiation. The most critical factors affecting width and depth of burn were the distance of the fiber tip from the tissue, and the medium in which the tissue was bathed. Of particular clinical importance was the fact that the burn width and depth drastically decreased when blood was present between the laser fiber and the tissue.

  11. Sequential multiphoton multiple ionization of atomic argon and xenon irradiated by x-ray free-electron laser pulses from SACLA

    International Nuclear Information System (INIS)

    We have investigated multiphoton multiple ionization of argon and xenon atoms at 5 keV using a new x-ray free electron laser (XFEL) facility, the SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan. The experimental results are compared with the new theoretical results presented here. The absolute fluence of the XFEL pulse has been determined with the help of the calculations utilizing two-photon processes in the argon atom. The high charge states up to +22 observed for Xe in comparison with the calculations point to the occurrence of sequential L-shell multiphoton absorption and of resonance-enabled x-ray multiple ionization. (paper)

  12. Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Lindley, R.A. [Michigan Univ., Ann Arbor, MI (United States)

    1993-10-01

    This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining {lambda}{sub o}; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.

  13. Anterior segment complications of retinal photocoagulation.

    Science.gov (United States)

    Kanski, J J

    1975-03-01

    Seven patients had anterior segment complications following xenon arc retinal photocoagulation. Irreversible keratopathy was induced in two cases; all patients showed evidence of iris injury. The absorption of radiation by the iris was considered the main factor in producing overheating of the anterior segment.

  14. Modeling of the initiation and evolution of a laser-ionized column in the lower atmosphere - 314.5 nm wavelength resonant multiphoton ionization of naturally occurring argon

    Science.gov (United States)

    Fetzer, G. J.; Stockley, J. E.

    1992-01-01

    A 3+1 resonant multiphoton ionization process in naturally occurring argon is studied at 314.5 nm as a candidate for providing a long ionized channel through the atmosphere. Results are presented which indicate peak electron densities up to 10 exp 8/cu cm can be created using laser intensities on the order of 10 exp 8 W/sq cm.

  15. In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars

    International Nuclear Information System (INIS)

    The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that

  16. Ionization of Argon n=2 (Ar+9 to Ar+16) by a 'relativistic' laser field

    International Nuclear Information System (INIS)

    The high field photoionization cross sections for the (n=2) shell of argon were measured with pulsed 800 nm radiation (27±5 fs duration) at an intensity of 1.5x1019 W/cm2±1x1019 W/cm2. The pondermotive energy for an electron at these field intensities is approximately 1 MeV. The best agreement with a calculated AC tunneling model was at an intensity of 0.6x1019 W/cm2. The difference between experimental and calculated relative charge state yields is less than an order of magnitude for Ar+9 to Ar+14 and Ar+16

  17. Successful surgical management of retinopathy of prematurity showing rapid progression despite extensive retinal photocoagulation

    Directory of Open Access Journals (Sweden)

    Salil S Gadkari

    2015-01-01

    Full Text Available The management of retinopathy of prematurity (ROP can be challenging in preterm babies with a gestational age <30 weeks, those with very low birth weight and multiple risk factors (eg., oxygen therapy for respiratory distress, sepsis, neonatal jaundice. A premature infant presented with "hybrid" zone 1 disease in the right eye and aggressive posterior ROP in the left eye. Both eyes were adequately treated with laser photocoagulation; however, the eyes deteriorated and progressed to stage 4 ROP. Both eyes eventually underwent intravitreal bevacizumab followed by lens sparing vitrectomy with good anatomical and visual outcome. Anticipation of progression despite laser photocoagulation in certain clinical scenarios, frequent follow-up and timely surgical intervention is paramount.

  18. Use of laryngeal mask airway in an extremely low birth weight premature infant undergoing laser photocoagulation treatment of retinopathy of prematurity with general anesthesia%喉罩通气道全麻用于超低出生体重儿视网膜病变激光光凝术的麻醉处理

    Institute of Scientific and Technical Information of China (English)

    马兰; 张建文; 左云霞

    2013-01-01

    报道1例胎龄27+4周,现月龄1月27 d,体重1.67 kg的超低出生体重伴双眼早产儿视网膜病变(retinopathy of prematurity,ROP)的早产儿在喉罩通气道全麻下行双眼激光光凝术治疗.%This case report describes the successful use of laryngeal mask airway in an extremely low birth weight premature infant undergoing laser photocoagulation treatment.The premature infant with gestational age of 27 ~ weeks is retinopathy in both eyes,57 d old,and 1.67 kg weight.

  19. Guiding of positive streamers in nitrogen, argon and N$_{2}$-O$_{2}$ mixtures by very low $n_{e}$ laser-induced pre-ionization trails

    CERN Document Server

    Nijdam, S

    2016-01-01

    In previous work we have shown that positive streamers in pure nitrogen can be guided by a laser-induced trail of low electron density. Here we show more detailed results from such measurements. We show the sensitivity of this laser-guiding on pressure p and found that the maximum delay between the laser pulse and voltage pulse for guiding scales with something between $1/p$ and $1/p^{2}$. We also show that when we use a narrower laser beam the laser guiding occurs less frequent and that when we move the laser beam away from the symmetry axis, guiding hardly is observed. Finally we show that laser guiding can also occur in pure argon.

  20. Cystoid macular edema after cataract surgery in a patient with previous severe iritis following argon laser peripheral iridoplasty

    Science.gov (United States)

    Bagnis, Alessandro; Saccà, Sergio Claudio; Iester, Michele; Traverso, Carlo Enrico

    2011-01-01

    This report describes a patient who had exaggerated responses to different inflammatory stimuli represented by laser and incisional surgery, respectively. These separate episodes should have a common link represented by a genetic predisposition to abnormal release of proinflammatory mediators within the eye. This 51-year old Hispanic woman showed a narrow iridocorneal angle with plateau iris configuration. Nd-YAG laser peripheral iridotomy was successfully performed to both eyes. No substantial changes in the iridotrabecular angle occurred despite patent iridotomies, thus confirming the diagnosis of plateau iris configuration. Argon laser iridoplasty was then performed to the right eye, while the left eye was scheduled for a later session. A severe inflammatory reaction within the anterior chamber developed after tapering of a one-week course of steroid therapy. Phacoemulsification of the lens was performed some months later when no signs of inflammation were detectable; no intraoperative complications occurred during surgery and an intraocular lens was placed. Cystoid macular edema developed four weeks after surgery despite no apparent risk factors, and resolved completely after anti-inflammatory medical therapy. Based on this case report, the unusual occurrence of severe iritis after laser treatment should be regarded as a risk factor for any other incisional or nonincisional procedures because it might indicate that the patient’s ocular tissues are prone to release of abnormally elevated proinflammatory mediators. Although further studies are needed to confirm this predisposition, prophylactic adjunctive topical nonsteroidal anti-inflammatory drug administration after cataract surgery should be considered in such cases in order to prevent potentially sight-threatening conditions. PMID:21573094

  1. Evaluation of Homogeneity and Elastic Properties of Solid Argon at High Pressures Using Picosecond Laser Ultrasonic Interferometry

    Science.gov (United States)

    Zerr, A.; Kuriakose, M.; Raetz, S.; Chigarev, N.; Nikitin, S. M.; Gasteau, D.; Tournat, V.; Bulou, A.; Castagnede, B.; Gusev, V. E.; Lomonosov, A.

    2015-12-01

    In picosecond ultrasonic interferometry [1], femto- or picosecond pump laser pulses are first used to generate acoustic pulses ranging from several to a few tens of nanometres length, thanks to the optoacoustic transduction in a light absorbing generator. Time-delayed femto- or picosecond probe laser pulses are then used to follow the propagation of these ultrashort acoustic pulses through a transparent medium that is in contact with the generator surface. The transient signal thus contains, at each moment in time, information on the local elastic, optical and elasto-optical properties of the tested material at the position where the laser-generated picosecond acoustic pulse is located during its propagation in the sample depth. Hence, the technique allows evaluation of sound velocities and elastic anisotropy of micro-crystallites composing a transparent material compressed to high pressures in a diamond anvil cell (DAC). This interferometry technique also helps to understand the micro-crystallite orientations in a case of elastically anisotropic material. Here we report the preliminary results of picosecond ultrasonic interferometry applied to the evaluation of homogeneities and elastic properties of polycrystalline solid argon compressed to 10 GPa and 15 GPa. In comparison with the earlier reported experiments on H2O ice at Mbar pressures [2], more efforts were spent to the evaluation of the lateral microstructure of the sample at high pressures, i.e., to inhomogeneities along the surface of the optoacoustic generator, rather than to the in-depth imaging along the axis of the DAC. The lateral imaging is performed over a distance of 60 - 90 µm, nearly corresponding to the complete sample diameter. In addition to the presence of expected lateral inhomogeneities the obtained results demonstrate important changes in their distribution upon pressure increase from 10 to 15 GPa. On the basis of the analysis of the statistic probability in the detection of differently

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

    Science.gov (United States)

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

    2014-04-01

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

  3. Continued Development of in Situ Geochronology for Planetary Using KArLE (Potassium-Argon Laser Experiment)

    Science.gov (United States)

    Devismes, D.; Cohen, B. A.

    2016-01-01

    Geochronology is a fundamental measurement for planetary samples, providing the ability to establish an absolute chronology for geological events, including crystallization history, magmatic evolution, and alteration events, and providing global and solar system context for such events. The capability for in situ geochronology will open up the ability for geochronology to be accomplished as part of lander or rover complement, on multiple samples rather than just those returned. An in situ geochronology package can also complement sample return missions by identifying the most interesting rocks to cache or return to Earth. The K-Ar radiometric dating approach to in situ dating has been validated by the Curiosity rover on Mars as well as several laboratories on Earth. Several independent projects developing in situ rock dating for planetary samples, based on the K-Ar method, are giving promising results. Among them, the Potassium (K)-Argon Laser Experiment (KArLE) at MSFC is based on techniques already in use for in planetary exploration, specifically, Laser-induced Breakdown Spectroscopy (LIBS, used on the Curiosity Chemcam), mass spectroscopy (used on multiple planetary missions, including Curiosity, ExoMars, and Rosetta), and optical imaging (used on most missions).

  4. Propagation dynamics of femtosecond laser pulses in a hollow fiber filled with argon: constant gas pressure versus differential gas pressure

    Science.gov (United States)

    Nurhuda, Muhammad; Suda, Akira; Midorikawa, Katsumi; Hatayama, Masatoshi; Nagasaka, Keigo

    2003-09-01

    We investigate the dynamics of femtosecond laser pulses propagating in a hollow fiber filled with argon, through a full numerical solution of the nonlinear Schrödinger equation. The simulation results show that, if the intensity is low and no ionization takes place, the spatial profile of the beam does not change very much so that its propagation model may be simplified to a one-dimensional model. If the intensity is high and ionization takes place, the spatial dynamics as well as temporal dynamics become very complicated because of self-focusing and defocusing. It is found that, for the same value of the B integral, self-focusing inside a hollow fiber can be substantially suspended by a differential gas pressure technique, where the gas pressure is set to be a minimum at the entrance and then increased with the propagation distance. Numerical simulations show that using such a technique, the energy transmitted during propagation inside hollow fiber is significantly enhanced, and the spatial phase is also improved.

  5. The effect observation of 532 nm laser panretinal photocoagulation combined with cyclopho-tocoagulation in the treatment of neovascular glaucoma%532nm 激光全视网膜光凝联合睫状体光凝治疗新生血管性青光眼疗效观察

    Institute of Scientific and Technical Information of China (English)

    郭娟

    2015-01-01

    Objective To observe the therapeutic effect of 532 nm laser panretinal photocoagulation combined with ciliary body photocoagulation therapy in the treatment of neovascular glaucoma (NVG).Methods A total of 16 NVG cases(16 eyes)were re-viewed in our study.This procedure mainly used panretinal photocoagulation and cyclophotocoagulation with the range of 90 to 180 de-gree after lensectomy and vitrectomy,and both anterior and posterior capsulorrhexis were performed .The intraocular pressure(IOP),vi-sion and complications were observed after operation .Results The IOP was significantly declined after operation (P <0.01) when compared with untreated NVG.In the follow-up,there was 1 case with vision improved,1 case with vision lost due to the hemorrhage of retina and 14 cases without vision change.During the follow-up period,no neovascular of the iris and anterior chamber angle were found in 14 cases.Neovascular on the surface of iris were observed in two cases .After the surgery,the average IOP was controlled within 20 mmHg.Conclusion The simultaneous treatments with intraocular panretinal photocoagulation and cyclophotocoagulation can deal with NVG.The operation is effective after long time observation and it is a safe and effective way for the end -stage NVG.It could be widely used in clinic.%目的:观察532 nm 激光全视网膜光凝联合睫状体光凝治疗新生血管性青光眼(neovascular glaucoma,NVG)的疗效。方法对16例 NVG 患者16只眼行晶状体玻璃体切除,并撕除晶状体前后囊膜,利用532μm 激光行全视网膜光凝,光凝90°~180°的睫状突,观察术后眼压、视力及并发症的情况。结果术后眼压均显著下降(P <0.01),1眼矫正视力提高,14眼视力无变化,1例发生视网膜再次出血后视力丧失。14只眼至末次随诊时虹膜及房角新生血管消退;2只眼虹膜表面仍可见纤细的新生血管,但眼压一直控制在20 mm Hg 以内。结论532μm 激

  6. Management of cyclosporine-induced gingival hyperplasia by use of an argon laser

    Science.gov (United States)

    Blankenau, Richard J.; Triolo, P.; Powell, G. L.

    1994-09-01

    This is a report of a case study with interesting laser applications. A 7 year old female was referred to us for treatment of hyperplastic tissue. At age two the patient had successfully undergone a liver transplant. She had undergone two periodontal surgeries under general anesthetic for the same soft tissue problem. Other possible complications were chronic sinusitis and frequent headaches. She has allergies to penicillin and sulfa. Her daily medications are Predisone and Cyclosporin. We consulted with her transplant team and they had no contraindication for the proposed dental surgery. The doctor placed her on prophylactic erythromycin for the procedure, as a preventive measure. The patient desired not to have any more general anesthetics administered. Clinical examination revealed electric pulp tests were normal for all teeth tested. No visible carious lesions were observed and there was no need for radiographs at this time. Soft tissue revealed red inflamed fibrous tissue consistent with gingival hyperplasia. Probing demonstrated 4 - 6 mm pockets around the anterior teeth.

  7. The Potassium-Argon Laser Experiment (KarLE): In Situ Geochronology for Mars and Beyond

    Science.gov (United States)

    Cohen, Barbara A.

    2014-01-01

    The search for life in the solar system depends upon discovering the right moments in planetary evolution: when habitable environments existed, when they declined, and when geologic processes operated to preserve traces of life after death. However, an incomplete knowledge of absolute Martian geochronology limits our ability to understand the timing of Martian evolutionary milestones, major climate changes, and stratigraphic epochs [1, 2]. Absolute dating relates these habitability markers to planetarywide geologic, atmospheric, and climate history places, and ties their occurrence to the history of the solar system, especially the Earth-Moon system and the timescale of evolution of life on Earth. KArLE is being developed to anchor the relative timeline of geological events to an absolute chronology that puts Mars into a wider solar system context. KArLE makes its measurements on rock samples that can be obtained by landers or rovers and inserted into a small, mechanically simple chamber. KArLE interrogates the samples using laser-induced breakdown spectrocopy (LIBS), mass spectrometry, and optical imaging. The KArLE experiment is flexible enough to accommodate any partner providing these instrument components, a creative approach that extends the ability of mission payloads to accomplish an additional highly-desirable science measurement for low cost and risk and minimal extra hardware.

  8. Modern retinal laser therapy

    OpenAIRE

    Kozak, Igor; Luttrull, Jeffrey K.

    2014-01-01

    Medicinal lasers are a standard source of light to produce retinal tissue photocoagulation to treat retinovascular disease. The Diabetic Retinopathy Study and the Early Treatment Diabetic Retinopathy Study were large randomized clinical trials that have shown beneficial effect of retinal laser photocoagulation in diabetic retinopathy and have dictated the standard of care for decades. However, current treatment protocols undergo modifications. Types of lasers used in treatment of retinal dise...

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

    Directory of Open Access Journals (Sweden)

    Sakai S.

    2013-11-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2013-11-01

    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.

  11. Optimal area of retinal photocoagulation necessary for suppressing active iris neovascularisation associated with diabetic retinopathy.

    Science.gov (United States)

    Shiraya, Tomoyasu; Kato, Satoshi; Shigeeda, Takashi

    2014-10-01

    To determine the optimal area of retinal photocoagulation required for suppressing active neovascularisation (NVI) associated with diabetic retinopathy. We studied 1 eye each of 4 patients in whom active NVI was ophthalmoscopically shown to have been suppressed by additional photocoagulation. These patients initially underwent pan-retinal photocoagulation for diabetic retinopathy at another hospital, but NVI developed subsequently. We compared the areas of photocoagulation before and after additional photocoagulation and compared the area of retinal photocoagulation. The photocoagulated areas before and after additional photocoagulation in the four eyes were 20.7 and 45.2, 36.6 and 56.3, 30.4 and 67.4, and 11.7 and 53.4 %, respectively. The area of retinal photocoagulation required to suppress active NVI is calculated to be ~50 %.

  12. ToF-SIMS and laser-SNMS analysis of Madin-Darby canine kidney II cells with silver nanoparticles using an argon cluster ion beam.

    Science.gov (United States)

    Nees, Ricarda; Pelster, Andreas; Körsgen, Martin; Jungnickel, Harald; Luch, Andreas; Galla, Hans-Joachim; Arlinghaus, Heinrich F

    2016-06-01

    The use of nanoparticles is one of the fastest expanding fields in industrial as well as in medical applications, owing to their remarkable characteristics. Silver nanoparticles (AgNPs) are among the most-commercialized nanoparticles because of their antibacterial effects. Laser postionization secondary neutral mass spectrometry (laser-SNMS) and time-of-flight secondary ion mass spectrometry in combination with argon cluster ion sputtering was used for the first time to investigate the effects of AgNPs on Madin-Darby canine kidney (MDCK) II cells. Depth profiles and high-resolution three dimensional (3D) images of nanoparticles and organic compounds from cells were obtained using an Ar cluster ion beam for sputtering and Bi3 (+) primary ions for the analysis. The 3D distribution of AgNPs and other organic compounds in MDCK II cells could be readily detected with very high efficiency, sensitivity, and submicron lateral resolution. The argon cluster ion beam is well suited for the sputtering of biological samples. It enables a high sample removal rate along with low molecular degradation. The outer membrane, the cytoplasm, and the nuclei of the cells could be clearly visualized using the signals PO(+) and C3H8N(+) or CN(+) and C3H8N(+). The laser-SNMS images showed unambiguously that AgNPs are incorporated by MDCK II cells and often form silver aggregates with a diameter of a few micrometers, mainly close to the outside of the cell nuclei. PMID:26671480

  13. Investigation of local thermodynamic equilibrium of laser induced Al2O3-TiC plasma in argon by spatially resolved optical emission spectroscopy

    Science.gov (United States)

    Alnama, K.; Alkhawwam, A.; Jazmati, A. K.

    2016-06-01

    Plasma plume of Al2O3-TiC is generated by third harmonic Q-switched Nd:YAG nanosecond laser. It is characterized using Optical Emission Spectroscopy (OES) at different argon background gas pressures 10, 102, 103, 104 and 105 Pa. Spatial evolution of excitation and ionic temperatures is deduced from spectral data analysis. Temporal evolution of Ti I emission originated from different energy states is probed. The correlation between the temporal behavior and the spatial temperature evolution are investigated under LTE condition for the possibility to use the temporal profile of Ti I emission as an indicator for LTE validity in the plasma.

  14. Investigation of local thermodynamic equilibrium of laser induced Al2O3–TiC plasma in argon by spatially resolved optical emission spectroscopy

    Directory of Open Access Journals (Sweden)

    K. Alnama

    2016-06-01

    Full Text Available Plasma plume of Al2O3–TiC is generated by third harmonic Q-switched Nd:YAG nanosecond laser. It is characterized using Optical Emission Spectroscopy (OES at different argon background gas pressures 10, 102, 103, 104 and 105 Pa. Spatial evolution of excitation and ionic temperatures is deduced from spectral data analysis. Temporal evolution of Ti I emission originated from different energy states is probed. The correlation between the temporal behavior and the spatial temperature evolution are investigated under LTE condition for the possibility to use the temporal profile of Ti I emission as an indicator for LTE validity in the plasma.

  15. 眼外导光照明视网膜光凝联合前房注气在白内障玻璃体视网膜术中应用%Microscopically eye light illumination, retinal laser photocoagulation combined with gas anterior chamber tamponade in cataract joint vitreoretinal surgery

    Institute of Scientific and Technical Information of China (English)

    刘鹏飞

    2016-01-01

    目的 探讨显微镜下眼外导光照明、视网膜激光光凝联合前房注气在白内障联合玻璃体视网膜手术中的疗效及可行性.方法 回顾性分析2010年1月至2014年7月在唐山市眼科医院就治的47例(47只眼)合并晶状体后囊破裂的眼内异物患者实施白内障联合玻璃体视网膜手术.其中周边视网膜格子样变性39只眼,视网膜裂孔者7只眼,玻璃体积血30只眼,视网膜脱离7只眼,锯齿缘解离2只眼.实施白内障摘除、玻璃体切除、视网膜光凝、人工晶状体植入、眼内注气术,术中显微镜下眼外导光照明、视网膜激光光凝联合前房注气.术后观察视力、人工晶状体、视网膜情况及并发症.术后随访6~11个月,平均(6.14±2.15)月.结果 47例患者中,42只眼充填C3F8,5只眼充填硅油.44只眼视力不同程度改善.41只眼人工晶状体正位,1只眼人工晶状体略偏斜.3只眼发生孔源性视网膜脱离.8只眼继发性青光眼,药物治疗1周至2周眼压恢复正常.2只眼角膜内皮面增生膜生长.结论 显微镜下眼外导光照明、视网膜激光光凝联合前房注气在白内障联合玻璃体视网膜手术中操作方便,安全可靠,减少了手术并发症发生,有很好的实用价值.此术式是白内障玻璃体视网膜联合手术的有力补充.%Objective To study the clinical efficacy and feasibility associated with microscopically eye light illumination,retinal laser photocoagulation combined with gas anterior chamber tamponade in the cataract joint vitreoretinal surgery.Methods It was a retrospective analysis of 47 cases (47 eyes) with intraocular foreign bodies and lens capsule rupture was performed cataract joint vitreoretinal surgery.Among 47 cases,peripheral lattice retinal degeneration in 39 eyes,peripheral retinal tear in 7 eyes,vitreous hemorrhage in 30 eyes,retinal detachment in 7 eyes,retinal serrated edge disintegrate in 2 eyes.The patients were performed cataract

  16. Evaluation of the hydrogen peroxide and special colorant effects under irradiation by argon and diode laser on tooth-whitening in vitro; Avaliacao do efeito de corantes especiais e peroxido de hidrogenio irradiados por laser de argonio e laser de diodo no clareamento dental 'in vitro'

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, Jose Antonio

    2003-07-01

    The aim of this study is to determine if there is any interaction between special colorant found on bleaching agents that have 35 % of hydrogen peroxide on its composition, and argon or diode laser. The first part of the study was to characterize the extrinsic stain obtained through a staining solution containing products present on the day by day diet of the general population. Thirty-two inferior human extracted incisors, free of caries and without filling material were selected for the study. The laser devices employed were Argon laser (AccuCure 3000 TM - Lasermed), wave length 488 nm, with a 200 mW/cm{sup 2} for 30 seconds in continuos mode; and diode laser (L 808 Medical Laser - Lasering do Brasil), wave length 808 {+-} 10 nm, with 1,6 W/cm{sup 2} for 30 seconds in continuos mode. The application mode done by a scanning movement over the buccal surface. The bleaching agents used were: Opalescence Extra (OE) - Ultradent Products USA, hydrogen peroxide 35%, gel with Carotene to convert light into heat; Pola Office (PO) - SDI - USA single doses of hydrogen peroxide; Whiteness HP (WHP) - FGM - Brasil, hydrogen peroxide 35%; Opus White (OW) - Sharplan - Israel, hydrogen peroxide 35%. The temperature rise measurement was performed with a thermocouple model 120-202-AJ, Fenwal, inserted into the pulpar chamber. The bleaching material was applied on the tooth surface with 2 mm thickness and then the irradiation was perform. The thirty two teeth were randomized in four groups, two for each laser device. The obtain data demonstrated a superior performance of the Argon laser on tooth whitening and also better results concerning the temperature rise. The alteration on tooth coloration was verified through digital spectrophotometer (Shade-Eye EX - Shofu) and quantitative analyses showed statistical differences among the groups. The bleaching results for Argon laser combined with OE and WHP were superior for the other groups. The mean variation of the temperature rise

  17. The application of laser plasma in ophthalmology

    International Nuclear Information System (INIS)

    The production and development of laser plasma are introduced, and the contribution of laser biomedicine and laser plasma technology to ophthalmology is analyzed. The latest three progresses (laser photocoagulation, photo-refractive keratotomy and laser iridectomy) of laser plasma applications in ophthalmology are presented

  18. Argon metastables in HiPIMS: validation of the ionization region model by direct comparison to time resolved tunable diode-laser diagnostics

    Science.gov (United States)

    Stancu, G. D.; Brenning, N.; Vitelaru, C.; Lundin, D.; Minea, T.

    2015-08-01

    The volume plasma interactions of high power impulse magnetron sputtering (HiPIMS) discharges operated with a Ti target is analyzed in detail by combining time-resolved diagnostics with modeling of plasma kinetics. The model employed is the ionization region model (IRM) with an improved and detailed treatment of the kinetics of the argon metastable (Arm) state, called m-IRM. The diagnostics used is tunable diode-laser absorption spectroscopy (TD-LAS) of the Arm state, which gives the line-of-sight density integrated along the laser path parallel to the target surface. The TD-LAS recordings exhibit quite complex temporal evolutions Arm(t), with distinct features that are shown to reflect the time evolution of the plasma (the electron density and temperature), and of the argon gas (gas rarefaction and refill). The Arm(t) function is thus a tracer for the most important aspects of internal discharge physics, and therefore suitable for model testing and validation. The IRM model is constructed to be locked to obey specific experimental macroscopic discharge parameters, specifically the discharge current ID(t) and the voltage UD(t). It has to this purpose been run with the appropriate process gas pressures (from 0.67 to 2.67 Pa), with the experimentally applied voltage pulse profiles UD(t), and with the resulting current pulse profiles ID(t) (with maxima from 0.5 to 70 A). It is shown that the model reproduces the features in the TD-LAS measurements: both the Arm(t) evolution in single pulses, and how the pulse shapes change with gas pressure and with pulse amplitude. The good agreement between the measurements and model output is in this work taken to validate the basic assumptions of the m-IRM. In addition, the m-IRM results have been used to unravel the connections between volume plasma kinetics and various features recorded in the TD-LAS measurement, and to generalize the foremost characteristics of the studied discharges.

  19. Behaviour of tunnelling transition rate of argon atom exposed to strong low-frequency elliptical laser field

    Indian Academy of Sciences (India)

    Miladinovic Tatjana B; Petrovic Violeta M

    2016-03-01

    We considered the tunnelling ionization of an electron under the influence of amonochromatic laser beam with the elliptical polarization. Arbitrary values of ellipticity were observed. The influence of ponderomotive potential and Stark shift on the ionization rate was discussed. A brief description of the dependence of the ponderomotive potential and the Keldysh parameter on the field intensity and ellipticity is given.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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 0.65lasers. T{sub g} is deduced from the absorption line shapes when scanning the laser wavelengths. The line profile, which is a Doppler broadening dominated Gaussian at gas pressures of p<10 mbar, changes to a Voigt shape at p>10 mbar, for which the pressure broadening can no more be neglected. T{sub g} is in the range of 480-750 K, increasing with pressure and decreasing with the distance from the microwave launcher. Taking into account the line of sight effects of the absorption measurements, a good agreement is found with our previous measurements by Rayleigh scattering of T{sub g} at the tube center. In the studied pressure range, the Ar(4 s) atom densities are in the order of 10{sup 16}-10{sup 18} m{sup -3}, increasing towards the end of the plasma column, decreasing with the pressure. In the low pressure side, a broad minimum is found around 10

  1. Behavior of argon gas release from manganese oxide minerals as revealed by 40Ar/39Ar laser incremental heating analysis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Manganese oxides in association with paleo- weathering may provide significant insights into the multiple factors affecting the formation and evolution of weathering profiles, such as temperature, precipitation, and biodiversity. Laser probe step-heating analysis of supergene hollandite and cryptomelane samples collected from central Queensland, Australia, yield well-defined plateaus andconsistent isochron ages, confirming the feasibility dating very-fined supergene manganese oxides by 40Ar/39Ar technique. Two distinct structural sites hostingAr isotopes can be identified in light of their degassing behaviors obtained byincremental heating analyses. The first site, releasing its gas fraction at thelaser power 0.2-0.4 W, yields primarily 40Aratm, 38Aratm, and 36Aratm (atmospheric Ar isotopes). The second sites yield predominantly 40Ar* (radiogenic 40Ar),39ArK, and 38ArK (nucleogenic components), at ~0.5-1.0 W. There is no significant Ar gas released at the laser power higher than 1.0 W, indicating the breakdown of the tunnel sites hosting the radiogenic and nucleogenic components. The excellent match between the degassing behaviors of 40Ar*, 39ArK, and 38ArK suggests that these isotopes occupy the same crystallographic sites and that 39ArK lossfrom the tunnel site by recoil during neutron irradiation and/or bake-out procedure preceding isotopic analysis does not occur. Present investigation supports that neither the overwhelming atmospheric 40Ar nor the very-fined nature of the supergene manganese oxides poses problems in extracting meaningful weathering geochronological information by analyzing supergene manganese oxides minerals.

  2. In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars; Estudo comparativo in vitro da capacidade adesiva da resina fotoativada pela luz halogena e por laser de argonio, utilizando-se brackets metalicos em pre-molares humanos

    Energy Technology Data Exchange (ETDEWEB)

    Carillo, Vitoria Eugenia Bismarck

    2004-07-01

    The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that

  3. Photocoagulation treatment for clinically significant radiation macular oedema

    Energy Technology Data Exchange (ETDEWEB)

    Kinyoun, J.L.; Zamber, R.W.; Lawrence, B.S.; Barlow, W.E.; Arnold, A.M. [Washington Univ., Seattle, WA (United States)

    1995-02-01

    Macular oedema is a leading cause of vision loss in patients with radiation retinopathy. In an effort to find an effective treatment for this vision threatening complication, 12 eyes (eight patients) were treated with photocoagulation for clinically significant radiation macular oedema (CSRMO) defined as central macular thickening, exudates threatening the macular centre, or one disc area of thickening in the macula. Median visual acuity improved from 20/100 pre-operatively to 20/90 at the initial post-operative examination (mean follow up 5 months) and to 20/75 at the final post-operative examination (mean follow up 39 months). At the final post-operative examination, visual acuity had improved in eight (67%) eyes and six (50%) eyes had complete resolution of the CSRMO; two (17%) other eyes had improved anatomically in that fewer CSRMO criteria were present. These results suggest that macular photocoagulation is effective in decreasing macular oedema and improving vision in eyes with CSRMO. (author).

  4. Combination of intravitreal bevacizumab and peripheral photocoagulation: an alternative treatment in eales disease.

    Science.gov (United States)

    Cp, Juarez; Al, Gramajo; Jd, Luna

    2013-01-01

    To report the efficacy of combination therapy (bevacizumab and photocoagulation) in a case of Eales Disease this study has been performed. Bevacizumab (Avastin, 1.25 mg/0.05 ml) was injected intravitreously for the treatment of iris and retinal neovascularization in a 56-year old Hispanic female with photocoagulation treatment to control the recurrence of vitreous haemorrhage. Our results revealed that stabilization of the disease and improvement in visual acuity were achieved without any signs of recurrence. Intravitreal bevacizumab in combination with photocoagulation treatment of ischemic retinal areas may be a good alternative for patients with recurrent vitreous haemorrhage due to Eales disease.

  5. Trace anesthetic gases during xenon arc photocoagulation for retinoblastoma.

    Science.gov (United States)

    Rosenberg, A M; Abramson, D H; Sussman, D; Servodidio, C; Turner, L

    1989-10-01

    In pediatric ocular examinations, administration of continuous-flow anesthetic gases containing nitrous oxide, halothane, and oxygen enables the physician to do safe, controlled, reproducible examinations. We did a study in which the levels of waste anesthetic gases were measured during xenon arc photocoagulation procedures used for retinoblastoma. Waste nitrous oxide and halothane gases measured during these procedures significantly exceeded the levels recommended by the National Institute of Safety and Health. These high levels are of particular importance because of the physician's proximity to the patient during the procedure. The high levels of waste gases may have immediate deleterious effects on the physician's functioning capacity and may also pose long-term health hazards for the physician and operating room personnel. PMID:2589745

  6. Comparative study of the "point-by-point technique" and the "scanning technique" for laser treatment of port-wine stain.

    Science.gov (United States)

    Mordon, S R; Rotteleur, G; Buys, B; Brunetaud, J M

    1989-01-01

    Photocoagulation using the argon laser has been proven to be an effective method for the treatment of port-wine stains (PWS). However, it is very difficult to reproduce the parameters of laser treatment. This leads to inaccurate energy dosages secondary to the difference in treatment patterns. The aim of this study was to compare the conventional point-by-point technique (PT) for PWS treatment against a new scanning technique (ST) using a device called "Hexascan" (PREIN & Partners, Ferney-Voltaire, France). A total of 249 patients (171 females and 78 males) using the argon laser have been studied in a retrospective study. Clinical results are presented. For each technique, blanching and hypertrophic scarring were examined. The results are classified into two groups: satisfactory and unsatisfactory. The clinical results show that the ST with the Hexascan is superior to the conventional PT. Scarring is drastically reduced because overdosage and overheating are avoided. Because of precisely controlled spot patterns, quality and homogeneity of blanching is improved. Treatment time can be reduced to 20% of that of the PT. PMID:2761335

  7. Depleted Argon from Underground Sources

    International Nuclear Information System (INIS)

    Argon is a strong scintillator and an ideal target for Dark Matter detection; however 39Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in 39Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO2 well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO2. We first concentrate the argon locally to 3% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation, and then the N2 and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO2 facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

  8. Utilização do laser de argônio na remoção de sutura corneana Use of argon laser in corneal suture removal

    Directory of Open Access Journals (Sweden)

    Edélcio Vieira

    2004-12-01

    Full Text Available OBJETIVO: Descrever a técnica da retirada de sutura em córnea clara, evitando-se o contato da parte externa do fio com o meio intra-ocular e avaliar se esse procedimento evitaria infecções. MÉTODOS: Foi realizado estudo retrospectivo de 1.233 casos de retirada de sutura de mononylon 10.0 em córnea clara, utilizando-se laser de argônio para cortar o fio, no qual se avaliou a incidência de infecções. RESULTADOS: Em 1.071 olhos, um tiro foi suficiente para cortar o ponto. Em 162 olhos, o tiro do laser atingiu a parte epitelial da sutura, sendo necessários disparos extras para cortar a parte intra-estromal e, assim, retirá-la sem que a parte externa do fio passasse pelo interior da córnea. Não ocorreram complicações após a retirada da sutura. CONCLUSÕES: A técnica utilizada mostrou-se eficaz na remoção das suturas e possivelmente apresenta risco menor de infecção, uma vez que a parte do fio sobrejacente ao epitélio não entra em contato com as camadas mais internas da córnea, nem com a câmara anterior, não tendo sido observado nenhum caso de infecção nesta pesquisa.PURPOSE: To describe the technique of clear-cornea suture removal, that avoids the contact of the external part of the thread with the intraocular medium, and to evaluate whether this procedure would prevent infections. METHODS: A retrospective study of 1.233 cases of clear-cornea mononylon 10.0 suture removal, by the use of an argon laser to cut the thread, was performed. Incidence of infection was then assessed. RESULTS: In 1.071 eyes, one shot was enough to cut the stitch. In 162 eyes, the laser shot hit the epithelial part of the suture, making new shots necessary to cut the intrastromal part, and thus to remove it assuring that the outer part of the stitch would not come in to contact with the interior of the cornea. There were no complications after suture removal. CONCLUSIONS: The technique has shown to be effective in suture removal. And, possibly

  9. Guiding of positive streamers in nitrogen, argon and N$_{2}$-O$_{2}$ mixtures by very low $n_{e}$ laser-induced pre-ionization trails

    OpenAIRE

    Nijdam, S.; Takahashi, E.

    2016-01-01

    In previous work we have shown that positive streamers in pure nitrogen can be guided by a laser-induced trail of low electron density. Here we show more detailed results from such measurements. We show the sensitivity of this laser-guiding on pressure p and found that the maximum delay between the laser pulse and voltage pulse for guiding scales with something between $1/p$ and $1/p^{2}$. We also show that when we use a narrower laser beam the laser guiding occurs less frequent and that when...

  10. Recent Developments in Laser Treatment of Diabetic Retinopathy

    OpenAIRE

    Yun, Samuel H.; Ron A. Adelman

    2015-01-01

    Laser photocoagulation has been the mainstay of diabetic retinopathy treatment since its development in mid-20 th century. With the advent of antivascular endothelial growth factor therapy, the role of laser therapy appeared to be diminished, however many advances in laser technology have been developed since. This review will describe recent advances in laser treatment of diabetic retinopathy including pattern scan laser, short-pulse duration and a reduced fluence laser, and navigated laser ...

  11. A Comparative Study of Retinal Function in Rabbits after Panretinal Selective Retina Therapy versus Conventional Panretinal Photocoagulation

    Directory of Open Access Journals (Sweden)

    Young Gun Park

    2015-01-01

    Full Text Available Purpose. This study evaluates functional changes in electroretinographic findings after selective retina therapy (SRT compared to panretinal photocoagulation (PRP in rabbits. Methods. The right eyes of 12 Chinchilla rabbits received 200 laser treatment spots. The right eyes of six rabbits received SRT (SRT group, whereas the other six animals were treated using PRP on the right eye (PRP group. The eyes were investigated using full-field ERG 1 hour and 3 weeks after treatment. Histologic exam to assess the tissue response of lasers was performed on 3 weeks. Results. No significant changes in the mean ROD or CR b-wave amplitudes of the SRT lesions were evident, compared to baseline, 1 h after laser treatment (p=0.372 and 0.278, resp.. In addition, the OPs and 30 Hz flickers of the SRT lesions were not significantly altered (p=0.17 and 0.243, resp.. At 3 weeks, similar results were found. Comparing the two groups, the ROD b-wave amplitude was reduced in the PRP and SRT groups to 60.04±4.2% and 92.32±6.43% of baseline (p<0.001. Histologically, there was no visible photoreceptor alterations on week 3. Conclusions. SRT in rabbit eyes induced less functional loss than PRP in both rod-mediated retinal function and cone-mediated retinal function. In addition, SRT irradiated eyes had no functional loss compared to its control.

  12. Argon in action

    CERN Multimedia

    Corinne Pralavorio

    2015-01-01

    Over the past few days, the SPS has been accelerating argon ions, which have started to be sent to the NA61/SHINE experiment. This operating mode, using a new type of ion, required a number of modifications to the accelerator.   Picture 1: a “super-cycle” of the SPS, featuring a proton cycle for the LHC, followed by an argon ion cycle for the North Area. Today, the accelerators are once again juggling particles and even performing completely new tricks. The SPS is supplying beams of argon ions for the first time, at energies never before achieved for this type of beam. They are destined for the NA61/SHINE experiment (see box) located in the North Area, which began receiving the beams on 11 February. Argon ions have a relatively large mass, as they consist of 40 nucleons, so they can be used in a similar way to lead ions. The main difficulty in accelerating them lies in the SPS, where the variation in acceleration frequency is limited. “The SPS was designed for a...

  13. Thermophysical properties of argon

    Energy Technology Data Exchange (ETDEWEB)

    Jaques, A.

    1988-02-01

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

  14. Análise química e morfológica do esmalte dentário humano tratado com laser argônio durante a colagem ortodôntica Chemical and morphological analysis of the human dental enamel treated with argon laser during orthodontic bonding

    Directory of Open Access Journals (Sweden)

    Glaucio Serra Guimarães

    2011-04-01

    Full Text Available INTRODUÇÃO: as principais utilizações do laser argônio na Ortodontia são a redução do tempo de polimerização durante a colagem ortodôntica e o aumento da resistência à cárie do esmalte dentário. OBJETIVO: o objetivo deste trabalho foi avaliar as alterações químicas e morfológicas do esmalte dentário humano tratado com laser argônio nos parâmetros da colagem ortodôntica. MÉTODOS: quinze primeiros pré-molares hígidos, extraídos por indicação ortodôntica, foram selecionados e seccionados no sentido do longo eixo em dois segmentos iguais. Uma metade de cada elemento dentário foi tratada e a outra permaneceu sem tratamento. Um total de 30 amostras foi analisado, criando o grupo laser (n = 15 e o grupo controle (n = 15. O tratamento foi feito com laser argônio com 250mW de potência por 5 segundos, com densidade de energia de 8J/cm². RESULTADOS: a análise de difração de raios X demonstrou duas fases em ambos os grupos, as fases apatita e monetita. A redução da fase monetita foi significativa após o tratamento com laser, sugerindo maior cristalinidade. A análise de Espectroscopia de Energia Dispersiva (EDS indicou aumento na razão cálcio-fósforo no grupo laser, compatível com a diminuição da fase monetita. A morfologia superficial do esmalte dentário apresentou-se mais lisa após o tratamento com laser argônio. CONCLUSÕES: o aumento de cristalinidade e a lisura superficial do esmalte no grupo laser são fatores sugestivos de aumento de resistência à cárie no esmalte dentário.INTRODUCTION: The main utilities of the argon laser in orthodontics are the high speed curing process in orthodontic bonding and the caries resistance promotion of the tooth enamel. OBJECTIVE: The objective of this study was to evaluate the chemical and morphological changes in the tooth enamel treated with the argon laser in the orthodontic bonding parameters. METHODS: Fifteen sound human first premolars, removed for orthodontic

  15. Clinical efficiency of of retinal laser photocoagulation with one time multi - point scanning mode and multiple time single - point mode in treatment with non proliferative diabetic retinopathy patients%单点多次和多点一次性完成视网膜激光光凝对非增生期糖尿病视网膜病变的临床疗效对比观察

    Institute of Scientific and Technical Information of China (English)

    杨喆; 相义会; 付颖

    2016-01-01

    Objective To explore the clinical efficiency of retinal laser photocoagulation with one time multi - point scanning mode and multiple time single - point mode in treatment with non proliferative diabetic retinopathy patients. Methods A total of 86 cases(102 eyes)of non proliferative diabetic retinopathy patients treated in hospital from June 2011 to June 2014 were randomly divided into study group of 43 cases(53 eyes)and the control group of 43 cases(49 eyes),study group underwent one time multi - point scanning mode,control group was given multiple time single - point mode,the laser energy,spot number,laser energy density of the two groups were compared,and detected visual threshold sen-sitivity,flash electroretinogram a,b wave and central macular thickness between two groups before and after 1 month,3 month,6 month treatment. Results The laser energy in the study group was significantly higher than that in the control group,the spot number,laser energy density was sig-nificantly lower than that in the control group( P 0. 05). There was no significant difference between the two groups before and after treatment in CMT( P > 0. 05). After treatment,visual threshold sensitivity,F - ERG a,b wave first showed reduce trend,and then gradually rised,after 1 month,3 month treatment visual threshold sensitivity,F - ERG a,b wave were significantly lower than before treatment( P 0. 05). There were no obvious perfusion area and neonatal blood vessels and other serious adverse reactions occurred during the 6 month follow - up period in two groups. Con-clusion The visual improvement effect of one time multi - point scanning mode and multiple time single - point mode in treatment with non prolif-erative diabetic retinopathy patients are similar,and one time multi - point scanning mode can significantly reduce the energy density,maximum reduction of laser treatment amage caused by the retina.%目的探讨单点多次和多点一次性完成视网膜激光光凝对非增生期糖

  16. Charge and energy transfer in argon-core-neon-shell clusters irradiated by free-electron-laser pulses at 62 nm

    Science.gov (United States)

    Sugishima, A.; Iwayama, H.; Yase, S.; Murakami, H.; Nagaya, K.; Yao, M.; Fukuzawa, H.; Liu, X.-J.; Motomura, K.; Ueda, K.; Saito, N.; Foucar, L.; Rudenko, A.; Kurka, M.; Kühnel, K.-U.; Ullrich, J.; Czasch, A.; Dörner, R.; Feifel, R.; Nagasono, M.; Higashiya, A.; Yabashi, M.; Ishikawa, T.; Togashi, T.; Kimura, H.; Ohashi, H.

    2012-09-01

    The multiple ionization of Ar-core-Ne-shell clusters in intense extreme-ultraviolet laser pulses (λ˜62 nm) from the free-electron laser in Japan was investigated utilizing a momentum imaging technique. The Ar composition dependence of the kinetic energies and the yields of the fragment ions give evidence for charge transfer from the Ar core to the Ne shell. We have extended the uniformly charged sphere model originally applied to pristine clusters [Islam , Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.73.041201 73, 041201(R) (2006)] to the core-shell heterogeneous clusters to estimate the amounts of charge and energy transfers.

  17. Liquid argon neutrino detectors

    CERN Document Server

    Battistoni, G

    2001-01-01

    The liquid argon imaging technique, as proposed for the ICARUS detector, offers the possibility to perform complementary and simultaneous measurements of neutrinos, as those of CERN to Gran Sasso beam (CNGS) and those from cosmic ray events. For the currently allowed values of the Super-Kamiokande results, the combination of both CNGS and atmospheric data will provide a precise determination of the oscillation parameters. Since one can observe and unambiguously identify nu /sub e/, nu /sub mu / and nu /sub tau / components, this technology allows to explore the full (3*3) mixing matrix. The same class of detector can be proposed for high precision measurements at a neutrino factory. (3 refs).

  18. Isentropic compression of argon

    Energy Technology Data Exchange (ETDEWEB)

    Veeser, L.R.; Ekdahl, C.A.; Oona, H. [and others

    1997-06-01

    The compression was done in an MC-1 flux compression (explosive) generator, in order to study the transition from an insulator to a conductor. Since conductivity signals were observed in all the experiments (except when the probe is removed), both the Teflon and the argon are becoming conductive. The conductivity could not be determined (Teflon insulation properties unknown), but it could be bounded as being {sigma}=1/{rho}{le}8({Omega}cm){sub -1}, because when the Teflon breaks down, the dielectric constant is reduced. The Teflon insulator problem remains, and other ways to better insulate the probe or to measure the conductivity without a probe is being sought.

  19. Regression Rates Following the Treatment of Aggressive Posterior Retinopathy of Prematurity with Bevacizumab Versus Laser: 8-Year Retrospective Analysis.

    Science.gov (United States)

    Nicoară, Simona D; Ștefănuţ, Anne C; Nascutzy, Constanta; Zaharie, Gabriela C; Toader, Laura E; Drugan, Tudor C

    2016-01-01

    BACKGROUND Retinopathy is a serious complication related to prematurity and a leading cause of childhood blindness. The aggressive posterior form of retinopathy of prematurity (APROP) has a worse anatomical and functional outcome following laser therapy, as compared with the classic form of the disease. The main outcome measures are the APROP regression rate, structural outcomes, and complications associated with intravitreal bevacizumab (IVB) versus laser photocoagulation in APROP. MATERIAL AND METHODS This is a retrospective case series that includes infants with APROP who received either IVB or laser photocoagulation and had a follow-up of at least 60 weeks (for the laser photocoagulation group) and 80 weeks (for the IVB group). In the first group, laser photocoagulation of the retina was carried out and in the second group, 1 bevacizumab injection was administered intravitreally. The following parameters were analyzed in each group: sex, gestational age, birth weight, postnatal age and postmenstrual age at treatment, APROP regression, sequelae, and complications. Statistical analysis was performed using Microsoft Excel and IBM SPSS (version 23.0). RESULTS The laser photocoagulation group consisted of 6 premature infants (12 eyes) and the IVB group consisted of 17 premature infants (34 eyes). Within the laser photocoagulation group, the evolution was favorable in 9 eyes (75%) and unfavorable in 3 eyes (25%). Within the IVB group, APROP regressed in 29 eyes (85.29%) and failed to regress in 5 eyes (14.71%). These differences are statistically significant, as proved by the McNemar test (P<0.001). CONCLUSIONS The IVB group had a statistically significant better outcome compared with the laser photocoagulation group, in APROP in our series. PMID:27062023

  20. DIAGNOSIS AND TREATMENT FOR DEGENERATIVE RETINOSCHISIS OF MEDIUM TO HIGH MYOPIA IN YOUNG ADULTS PRIOR TO LASER-ASSISTED IN SITU KERATOMILEUSIS SURGERY

    Institute of Scientific and Technical Information of China (English)

    孙昕; 冯佩丽; 闫焱

    2013-01-01

    <正>Objective To discuss the characteristics of degenerative retinoschisis in young adults with medium to high myopia prior to laser-assisted in situ keratomileusis(LASIX) surgery and the significance of preventive photocoagulation.Methods A total of 32 eyes in 19 patients suffering from myopia combined with degenerative retinoschisis were included.The mean best-corrected visual acuity was 0.82±0.13 and the mean spherical equivalent of the subjective refraction was -(6.50±3.98) Diopter. The patients underwent preventive photocoagulation 1 month before the laser surgery for myopia.Results All the eyes that received preventive photocoagulation for retinoschisis had no further progression or retinal detachment during 4-year period of follow-up.Conclusion The degenerative retinoschisis in young adults should be recognized and treated with preventive photocoagulation.This may prevent further damage of visual field and other complications of slowly progressive retinoschisis after LASIK surgery.

  1. Combined Phacoemulsification, Vitrectomy and Endolaser Photocoagulation in Patients with Diabetic Retinopathy and Cataract

    International Nuclear Information System (INIS)

    Objective: To determine the outcomes of early vitrectomy and endolaser photocoagulation effects during phacoemulsification in cataractous eyes with diabetic retinopathy. Study Design: Descriptive study. Place and Duration of Study: Ophthalmology Department Unit-II, DUHS, Civil Hospital, Karachi, and Al-Noor Eye Clinic, Karachi, from February 2009 to December 2010. Methodology: Consecutive 54 patients with 7 - 15 years duration of type II diabetes with severe non-proliferative diabetic retinopathy (NPDR) and early proliferative diabetic retinopathy (PDR) who had cataract grade I and II underwent vitrectomy, endolaser photocoagulation and phacoemulsification with IOL implantation. Best corrected visual acuity was main outcomes measure assessed till 6 months follow-up. Results: Out of 54 eyes, 32 patients were females and 22 were males. Majority 47 (87%) eyes gained significant (p < 0.001) improvement of best corrected visual acuity of four lines or better while 5 (9.3%) eyes retained stable visual acuity. In only 2 eyes, vision declined to 3/60 or less. Conclusion: Early vitrectomy with phacoemulsification in severe NPDR and early PDR patients, if assisted or augmented with endolaser photocoagulation, maximizes, early visual rehabilitation with less morbidity and may retard progression of retinopathy. (author)

  2. Depleted argon from underground sources

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  3. Multidimensional intermolecular dynamics from tunable far-infrared laser spectroscopy: Angular-radial coupling in the intermolecular potential of argon--H2O

    International Nuclear Information System (INIS)

    Five new vibration--rotation tunneling states of Ar--H2O [the Σ and Π(111) and the Σ and Π(212) internal rotor states and the n=1, Π(101) stretching-internal rotor combination level] have been accessed by tunable far-infrared laser spectroscopy. The measured vibrational band origins of transitions to these states are within 2% of predictions made from an anisotropic three-dimensional intermolecular potential surface (denoted AW1) derived from a nonlinear least-squares fit to previous far-infrared spectral data [J. Phys. Chem. 94, 7991(1990)]. This provides strong evidence that the AW1 intermolecular potential surface incorporates much of the essential physics of the intermolecular forces which bind the cluster. However, larger deviations from the predictions are found in the observed rotational term values. A detailed analysis of these deviations clearly demonstrates the need for even stronger angular-radial coupling in the Ar--H2O intermolecular potential than the already substantial coupling present in the AW1 surface. Specifically, the presently observed Σ(111) state and the n=1, Σ(000) state are found to be approximately 65:35 mixtures of the basis states which represent pure stretching and internal rotation. The Σ(212) level is found to be mixed just as strongly with n=2, Σ(101). The formalism for accurately deperturbing vibration--rotation--tunneling states coupled by Coriolis interactions used in the above analysis is presented

  4. Intravitreal bevacizumab injection alone or combined with macular photocoagulation compared to macular photocoagulation as primary treatment of diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Jovanović Sandra

    2015-01-01

    Full Text Available Background/Aim. Within diabetic retinopathy (DR, diabetic macular edema (DME is one of the leading causes of the loss of visual acuity. The aim of this study was to determine the efficacy of the intravitreal vascular endothelial growth factor (VEGF inhibitor application alone or combined with macular focal/grid lasephotocoagulation compared with laser treatment alone. Methods. This prospective randomized clinical trial included 72 patients (120 treated eyes with varying degrees of DR and DME. The DME treatment included intravitreal VEGF inhibitor bevacizumab (Avastin® application, with and without laser treatment. Bevacizumab (1.25 mg/0.05 mL was administered intravitreally in 4-6-week intervals. Laser is applied 4-6 weeks after last dose of the drug as a part of combined treatment, or as the primary treatment. Results. The mean reduction in central macular thickness (CMT for the eyes (n = 31 treated with bevacizumab alone was 162.23 μm, for the eyes (n = 53 treated with combined treatment the mean reduction in CMT was 124.24 μm, both statistically significant at p < 0.001. Laser macular photocolagulation as a part of combined treatment (in 53 eyes significantly contributed to the CMT reduction, based on the paired t-test results (366.28 vs 323.0 μm at p < 0.05. In our study, the mean visual acuity improvement of 0.161 logMAR was achieved in the group of eyes treated with bevacizumab alone, and 0.093 logMAR in the group with combined treatment, both statistically significant at p < 0.05. The effect of laser photocolagulation alone on visual acuity and CMT was not statistically significant. Conclusion. Treatment with bevacizumab alone or within combined treatment is more effective in treating DME than conventional macular laser treatment alone, both anatomically and functionally.

  5. The Liquid Argon Purity Demonstrator

    CERN Document Server

    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

    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.

  6. The Liquid Argon Purity Demonstrator

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  7. Pain and accuracy of focal laser treatment for diabetic macular edema using a retinal navigated laser (Navilas®

    Directory of Open Access Journals (Sweden)

    Kampik A

    2012-02-01

    Full Text Available Marcus Kernt*, Raoul E Cheuteu*, Sarah Cserhati, Florian Seidensticker, Raffael G Liegl, Julian Lang, Christos Haritoglou, Anselm Kampik, Michael W Ulbig, Aljoscha S Neubauer Department of Ophthalmology, Ludwig Maximilian University of Munich, Germany*These authors contributed equally to this studyAim: To investigate treatment-related pain and the accuracy of navigated laser photocoagulation in the treatment of clinically significant macular edema.Methods: Focal laser treatment of diabetic macular edema in 54 consecutive patients was digitally planned on fundus images and performed using the navigated laser photocoagulation system Navilas® (OD-OS GmbH, Teltow, Germany. Treatment-related pain was quantified on a visual analog scale directly after treatment and compared with a matched control group who received conventional laser treatment (n = 46. In addition, for Navilas-treated patients, the accuracy of spot placement on color images was analyzed 1 month after treatment.Results: In total, 5423 laser spots (mean 100 per eye were analyzed. With navigated treatment, 90% of laser spots were visible on color images, of which 96% were within 100 µm from the target. Eighty percent of the laser spots were placed and visible within the 100 µm target on an intention-to-treat basis for color imaging. Optical coherence topography confirmed that laser effects were limited to the outer retina. Treatment-related pain following navigated laser photocoagulation was significantly lower than that of conventional laser treatment (1.6 vs 4.4 on a visual analog scale, P < 0.001.Conclusion: Navigated laser effects could be visualized to a high percentage on post-treatment color images, and their location showed a high concordance to targeted areas. Patients reported that treatment-related pain following Navilas laser photocoagulation was significantly lower than pain following conventional laser treatment.Keywords: diabetic retinopathy, navigated laser therapy

  8. Intravitreal bevacizumab injection alone or combined with macular photocoagulation compared to macular photocoagulation as primary treatment of diabetic macular edema

    OpenAIRE

    Jovanović Sandra; Čanadanović Vladimir; Sabo Ana; Grgić Zorka; Mitrović Milena; Rakić Dušan

    2015-01-01

    Background/Aim. Within diabetic retinopathy (DR), diabetic macular edema (DME) is one of the leading causes of the loss of visual acuity. The aim of this study was to determine the efficacy of the intravitreal vascular endothelial growth factor (VEGF) inhibitor application alone or combined with macular focal/grid lasephotocoagulation compared with laser treatment alone. Methods. This prospective randomized clinical trial included 72 patients (120 treated e...

  9. Efficacy of patterned scan laser in treatment of macular edema and retinal neovascularization

    Directory of Open Access Journals (Sweden)

    Dimple Modi

    2009-08-01

    Full Text Available Dimple Modi, Paulpoj Chiranand, Levent AkdumanSaint Louis University School of Medicine, Department of Ophthalmology, Saint Louis University Eye Institute, St. Louis, Missouri, USAPurpose: To analyze the benefits, efficacy, and complications of the PASCAL® photocoagulation laser system (OptiMedica, Santa Clara, CA, USA in patients treated at our institution.Methods: We conducted a retrospective chart review of 19 patients (28 eyes who underwent laser treatment using the PASCAL® photocoagulation system from November 2006 to November 2007. These 28 eyes were divided into two groups; group 1 eyes underwent macular grid laser and group 2 eyes underwent panretinal photocoagulation. Treatment was performed for macular edema or for iris or retinal neovascularization. Outcomes measured included best-corrected visual acuity (BCVA, efficacy of laser treatment, complications, duration of the procedure, and pain perception, which were noted in the charts for panretinal treatments.Results: Follow-up was 5.9 ± 2.6 months for group 1 and 5.9 ± 4.0 months for group 2. In group 1, 9/28 eyes required a second treatment for remaining edema. BCVA was stable or better in 66% (14/21 and average central foveal thickness on ocular coherence tomography improved in 71% (15/21. Time to completion for a number of laser patterns for grid photocoagulation was felt to be too long for completing the total pattern safely, although we have not noted any related complications. In group 2, the neovascularization regressed at least partially in 3/7 patients. Patient-reported pain perception was 3.6 on a scale of 1 to 10 for group 2. Occasional hemorrhages occurred secondary to irregular laser uptake at different spots in the patterns. We observed no visual outcome consequences because of these hemorrhages during follow-up.Conclusions: Retinal photocoagulation by the PASCAL® laser has comparable efficacy to historical results with conventional retinal photocoagulation in short

  10. Low vision aid in exudative macular degeneration treated by photodynamic therapy and thermal laser photocoagulation%光动力治疗和热激光光凝治疗渗出性黄斑变性所致低视力

    Institute of Scientific and Technical Information of China (English)

    Montero JA; Ruiz-Moreno JM; Sanchez-de Castro MJ; Fabiani C

    2006-01-01

    · AIM: To determine the efficacy of low vision rehabilitation (LVR) in patients with age related macular degeneration (AMD) treated by photodynamic therapy (PDT) compared to those treated by thermal laser (TLP).examining the files of 42 patients (42 eyes) with AMD who had been treated either by TLP (Group 1) and PDT (Group 2). Once AMD was considered to be inactive they underwent visual rehabilitation in the LVR Unit in order to increase their ability for distant and near vision.received TLP. Average corrected visual acuity after laser therapy was 0.14 in Group 1, and 0.16 in Group 2. No statistically significant differences were found between both groups before and after laser therapy. Both groups showed improvement after LVR; however, statistically significant differences between both groups were found only for near vision.both PDT and TLP are associated to a decreased visual acuity after treatment, LVR may be more successful for near vision among patients treated by PDT%目的:比较观察光动力治疗(PDT)和热激光光凝(TLP)治疗对年龄相关性黄斑变性(AmD)患者低视力(LVR)的临床疗效.方法:对42例(42眼)AMD患者资料进行回顾性研究,其分别行TLP治疗(组1)或PDT治疗(组2).一旦确定AMD处于非活动期,患者在LVR部进行视力康复,以提高其远、近视功能.结果:18眼接受了PDT治疗,24眼进行TLP治疗.激光治疗后,组1患者的平均最佳矫正视力为0.14,组2平均为0.16.两组比较,视力于激光治疗前后都没有统计学差异;两组的LVR都有提高,但两组中只有近视力比较有统计学差异.结论:本研究结果表明,PDT和TLP治疗后患者的视力均有所下降,PDT治疗时,LVR患者近视力改善更为有效.

  11. Diode laser based light sources for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André; Marschall, Sebastian; Jensen, Ole Bjarlin;

    2013-01-01

    Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode...... lasers simultaneously offer tunability, high-power emission and compact size at fairly low cost. Therefore, diode lasers are increasingly preferred in important applications, such as photocoagulation, optical coherence tomography, diffuse optical imaging, fluorescence lifetime imaging, and terahertz...... imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications....

  12. Cicatrização da membrana timpânica na timpanocentese com laser de argônio comparado à técnica com microlanceta: estudo experimental em ratos Tympanic membrane healing in myringotomies performed with argon laser or microknife: an experimental study in rats

    Directory of Open Access Journals (Sweden)

    Lucio Almeida Castagno

    2006-12-01

    times were equivalent. All myringotomies healed within 10 days. CONCLUSION: Argon laser assisted myringotomy healed just as early on as incisional myringotomy on Wistar rats without middle ear diseases.

  13. Molecular formation dynamics of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one, 1,3,5-trinitroperhydro-1,3,5-triazine, and 2,4,6-trinitrotoluene in air, nitrogen, and argon atmospheres studied using femtosecond laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Femtosecond laser induced breakdown spectroscopic (LIBS) studies were performed on three high energy materials namely 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and 2,4,6-trinitrotoluene (TNT). LIBS spectral features were obtained for these samples in three different atmospheres i.e. air, nitrogen, and argon. Different molecular to elemental ratios in these three atmospheres were investigated in detail. CN/C and CN/N ratios were observed to be prominent in nitrogen and air atmospheres. We attempt to elucidate the role of several reactions involving CN molecular formation in connection with discrepancies obtained in the measured ratios. The complete temporal dynamics of atomic C (247.82 nm) and CN (388.20 nm) molecular species in three different atmospheres are elaborated. The decay rates of C peak were found to be longest (96 ns–121 ns) in argon atmosphere for all the samples. The decay rates of CN peak (388.2 nm) were longer (161 ns–364 ns) in nitrogen compared to air and argon atmospheres. We also attempt to explicate the decay mechanisms with respect to the molecular species formation dynamics in different atmospheres. - Highlights: • LIBS studies of NTO, RDX, and TNT in nitrogen, air, and argon were performed using fs pulses. • Decay constants of C, CN in three atmospheres were recorded systematically. • Different molecular to elemental ratios were investigated in detail. • CN/C and CN/N ratios were observed to be prominent in nitrogen and air atmospheres

  14. First measurements with ARGONTUBE, a 5 m long drift Liquid Argon TPC

    International Nuclear Information System (INIS)

    The Liquid Argon Time Projection Chamber (LAr TPC) technique is a promising technology for future neutrino detectors. At LHEP of the University of Bern (Switzerland), an R and D program towards large detectors are on-going. The main goal is to show the feasibility of long drift paths over many meters. Therefore, a liquid Argon TPC with 5 m of drift distance was constructed. Many other aspects of the liquid Argon TPC technology are also investigated, such as a new device to generate high voltage in liquid Argon (Greinacher circuit), a recirculation filtering system and the multi-photon ionization of liquid Argon with a UV laser. Two detectors are built: a medium size prototype for specific detector technology studies, and ARGONTUBE, a 5 m long device

  15. Protective Effects of Radix Pseudostellariae Extract Against Retinal Laser Injury

    Directory of Open Access Journals (Sweden)

    Guo Rui

    2014-05-01

    Full Text Available Background: This study aimed to analyze the protective effects of a saponin extract from Radix Pseudostellariae (RP on retinal laser injury based on a retinal photocoagulation model. Methods: Fifty-eight rabbits were randomly divided into three groups: Group A (saponin extract orally, Group B (physiological saline, and Group C (control. The animals were sacrificed 1 day, 7 days, 14 days, and 30 days after photocoagulation and lesions were evaluated with fundus photography, light microscopy, and electron microscopy. Superoxide dismutase (SOD and malondialdehyde (MDA levels were measured, and expression levels of c-fos and Bax genes were also determined. Results: The lesion sizes in Group A were smaller than in Group B. The levels of SOD in Group B were significantly lower than in groups A and C (PConclusion: The saponin extract of RP can inhibit oxidative stress, downregulate the levels of c-fos and Bax gene expression, and inhibit apoptosis in the retina after photocoagulation.

  16. Laser application in tracheobronchial tumors

    Science.gov (United States)

    Rau, B. Krishna; Krishna, Sharon

    2004-09-01

    Ninety three patients with obstructing tracheobronchial tumors were treated with Neodymium: Yttrium - Aluminum - Garnet (Nd:YAG) laser photocoagulation over a period of six years. There were sixty seven Males and 26 Females with a mean age of 44.3 years (range 6- 79 years). 21 benign and 72 malignant lesions were treated with a total 212 sessions of laser photocoagulation (mean 2.4 sessions). The anatomical distribution of lesions were as follows; larynx 9 (three benign and 6 malignant) trachea 39 (27 benign and 12 malignant) left main bronchus 27 (14 malignant) right main bronchus 24 (14 malignant) and vocal cords - 9 (three malignant). There were 21 patients with squamous cell carcinoma, two adenocarcinomas, one adenoid cystic carcinoma, 7 cases of locally infiltrating tumors from thyroid and esophagus, 6 cases of carcinoid tumor and 16 benign lesions. Twenty one patients had a tracheostomy tube in place when treatment was started. Eighteen of the 21 patients with tracheostomy were weaned off the tube in a mean of 5.5 days from the start of treatment. Lumen was restored in 31 (79.4%) patients. In the other eight (20.6%), lumen was achieved, but not sustained. Complications included bleeding in three cases which were managed conservatively, two cases of pneumothorax, and four cases of bronchospasm. There were six deaths during the follow up but none attributable to the procedure. Laser photocoagulation offered effective treatment in the majority of patients with obstructing tracheobronchial tumors, with acceptable morbidity.

  17. Dentine bond strength of a composite resin polymerized with conventional light and argon laser Resistência de união à dentina de resina composta polimerizada com luz halógena e laser de argônio

    Directory of Open Access Journals (Sweden)

    Patricia Ramos Lloret

    2004-09-01

    Full Text Available The use of argon laser (488 nm has been suggested as a new alternative for polymerizing adhesive materials. This study aimed to evaluate the tensile bond strength of a microfilled composite (A110, 3M inserted by incremental technique (3 increments of 1 mm and by single increment (3 mm polymerized by argon laser for 10, 20 and 30 seconds and halogen light for 40 seconds. Eighty (8 groups of 10 teeth freshly extracted bovine teeth were stored in a freezer in distilled water for one week. The crowns were cross-sectioned from the roots. Pulpectomy was performed and the pulp chambers were sealed with wax. The buccal surfaces of the teeth were ground with wet sandpaper (grains: 120, 400, and 600 to expose the surface dentin, and the teeth were then included in acrylic resin. A metal device was used to fix each sample and a black propylene matrix25 (3 mm high with an internal millimetric delimitation was used to insert the material according to the groups studied. The polymerization intervals were of 10, 20 and 30 seconds for the laser polymerization and 40 seconds for the conventional polymerization. Tensile tests were performed by a Universal Testing Machine 4442 (Instron at a speed of 0.5 mm/min and 500 N load. According to the methodology used, the incremental technique increased bond strength values. There was no difference between the studied polymerization techniques when resin was filled in 3 increments.O uso do laser de argônio (488 nm tem sido sugerido como uma nova alternativa para polimerização de materiais adesivos. Este estudo tem o objetivo de avaliar a resistência adesiva de uma resina composta microparticulada (A110, 3M inserida pela técnica incremental (3 incrementos de 1 mm e de incremento único (3 mm polimerizada com laser de argônio por 10, 20 e 30 segundos e com luz halógena por 40 segundos. Oitenta (8 grupos com 10 dentes dentes bovinos recém-extraídos foram armazenados em geladeira, em água destilada, por uma semana

  18. Fano factor in pure argon

    International Nuclear Information System (INIS)

    The Fano factor for 5.3 MeV alpha particles in pure argon has been measured with a gridded ionization chamber and estimated to be 0.20 (+0.01-0.02). The obtained value is consistent with the theoretical value if the contribution of elastic nuclear collisions to the Fano factor is taken into the consideration. There is no appreciable difference between the values for pure argon and for a gas mixture of Ar (10%)CH4 obtained in the previous measurement. (orig.)

  19. Improvement in retinal venous oxygen saturation after panretinal photocoagulation is predictive of progression of proliferative diabetic retinopathy

    DEFF Research Database (Denmark)

    Torp, Thomas Lee; Kawasaki, Ryo; Wong, Tien Yin;

    We performed a prospective, interventional clinical study on patients with proliferative diabetic retinopathy (PDR) in order to investigate changes in retinal oximetry before and three months after panretinal photocoagulation (PRP) and to correlate this to PDR-activity. Thirty-nine eyes from 34 p...

  20. Attainable superheat of argon-helium, argon-neon solutions.

    Science.gov (United States)

    Baidakov, Vladimir G; Kaverin, Aleksey M; Andbaeva, Valentina N

    2008-10-16

    The method of lifetime measurement has been used to investigate the kinetics of spontaneous boiling-up of superheated argon-helium and argon-neon solutions. Experiments were made at a pressure of p = 1.5 MPa and concentrations up to 0.33 mol% in the range of nucleation rates from 10 (4) to 10 (8) s (-1) m (-3). The homogeneous nucleation regime has been distinguished. With good agreement between experimental data and homogeneous nucleation theory in temperature and concentration dependences of the nucleation rate, a systematic underestimation by 0.25-0.34 K has been revealed in superheat temperatures over the saturated line attained by experiment as compared with theoretical values calculated in a macroscopic approximation. The revealed disagreement between theory and experiment is connected with the dependence of the properties of new-phase nuclei on their size.

  1. Avaliação da camada de fibras nervosas na retinopatia diabética tratada por panfotocoagulação com laser de argônio Examination of the retinal nerve fiber layer in diabetic retinopathy treated by argon laser panphotocoagulation

    Directory of Open Access Journals (Sweden)

    Otacílio de Oliveira Maia Júnior

    2008-04-01

    Full Text Available OBJETIVO: Avaliar alterações na camada de fibras nervosas da retina na retinopatia diabética tratada por panfotocoagulação com laser de argônio. MÉTODOS: Estudo prospectivo de portadores de retinopatia diabética submetidos a panfotocoagulação retiniana. Inicialmente, foram realizados exame oftalmológico completo e tomografia de coerência óptica. Todos pacientes foram submetidos a panfotocoagulação em um dos olhos. A camada de fibras nervosas foi avaliada por meio da tomografia de coerência óptica na 1ª semana, no primeiro, terceiro e sexto meses do tratamento. RESULTADOS: A amostra foi composta por 27 pacientes (27 olhos portadores de diabetes mellitus tipo 2. A idade variou entre 41 e 64 anos (média de 53,7 ± 6,2 anos, sendo 10 (37% pacientes do sexo masculino e 17 (63% do feminino. Quanto ao tipo de retinopatia, 22,2% apresentavam RD proliferativa e 77,8%, RD não proliferativa muito grave. Houve aumento significante nas medidas da espessura da camada de fibras nervosas, permanecendo nos setores temporal, 3 e 4 horas após seis meses de seguimento. Não foi observada qualquer redução na espessura em todos parâmetros analisados. CONCLUSÃO: Não foi evidenciada, a curto e médio prazo, redução na espessura da camada de fibras nervosas em portadores de retinopatia diabética tratada por panfotocoagulação que possa ser identificável por meio da tomografia de coerência óptica. Por outro lado, alguns setores mostraram aumento na espessura durante o seguimento.PURPOSE: To evaluate the alterations in the retinal nerve fiber layer in diabetic retinopathy treated by argon laser panphotocoagulation. METHODS: Prospective study of patients with diabetic retinopathy submitted to retinal panphotocoagulation. Initially, complete ophthalmologic examination and optical coherence tomography were performed. All patients were submitted to panphotocoagulation with argon laser in one of the eyes. The retinal fiber layer was evaluated

  2. Liquid Argon Barrel Cryostat Arrived

    CERN Multimedia

    Pailler, P

    Last week the first of three cryostats for the ATLAS liquid argon calorimeter arrived at CERN. It had travelled for 46 days over several thousand kilometers from Japan to CERN. During three years it has been fabricated by Kawasaki Heavy Industries Ltd. at Harima, close to Kobe, under contract from Brookhaven National Laboratory (BNL) of the U.S.. This cryostat consists of two concentric cylinders made of aluminium: the outer vacuum vessel with a diameter of 5.5 m and a length of 7 m, and the inner cold vessel which will contain the electromagnetic barrel calorimeter immersed in liquid argon. The total weight will be 270 tons including the detectors and the liquid argon. The cryostat is now located in building 180 where it will be equipped with 64 feed-throughs which serve for the passage of 122,880 electrical lines which will carry the signals of the calorimeter. After integration of the calorimeter, the solenoidal magnet of ATLAS will be integrated in the vacuum vessel. A final cold test of the cryostat inc...

  3. Effect of ultrasound-guided interstitial laser photocoagulation on benign solitary solid cold thyroid nodules

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbaek, Finn Noe; Hegedüs, Laszlo

    2006-01-01

    power of 2.5-3.5 W. Thyroid nodule volume was assessed by US. Pressure and cosmetic complaints were evaluated on a visual analogue scale. MAIN OUTCOME: In the ILP- 1 group, thyroid nodule volume decreased from 10.1 +/- 4.3 mL (mean +/- standard deviation [SD]) to 5.7 +/- 3.2 mL (p = 0.......0004), and in the ILP-3 group from 10.8 +/- 5.5 mL to 4.6 +/- 3.0 mL (p = 0.0005) during follow-up. The overall mean difference between the two groups was 13%, corresponding to an improved mean thyroid nodule volume reduction of 30% (p = 0.03). In both groups subjective symptoms were significantly reduced, and without...... with a cytologically benign solitary solid and scintigraphically cold thyroid nodule causing local discomfort were assigned to one session of ILP (ILP-1) (n = 15) or three monthly ILP sessions (ILP-3) (n = 15) and followed for 6 months. ILP was performed under continuous ultrasound (US)--guidance and with an output...

  4. Treatment of twin-twin transfusion syndrome by fetoscopic laser photocoagulation

    Institute of Scientific and Technical Information of China (English)

    劉子建; 梁德楊; 馮德源; 梁子昂

    2004-01-01

    @@ Twin-twin transfusion syndrome (TTTS) is a serious obstetric complication, occurring in about 15% of monochorionic (MC) twin pregnancies. If untreated, the prognosis is poor, with an overall perinatal mortality of 80%.1 It is now clear that TTTS is the result of an unbalanced unidirectional blood flow through placental arteriovenous anastomoses (also termed deep anastomoses) between the two fetal circulations.2 The donor twin progressively becomes anemic, and develops growth restriction, oliguria, and oligohydramnios/anhydramnios; whereas the recipient becomes plethoric and polyuric, and develops congestive heart failure, cardiomegaly, polyhydramnios and fetal hydrops. Preterm labor is common because of gross polyhydramnios, and further deteriorations will lead to intrauterine death of both twins.

  5. PHACES syndrome: Diode laser photocoagulation of intraoral hemangiomas in six young patients

    Directory of Open Access Journals (Sweden)

    Gianfranco Favia

    2015-01-01

    Conclusions: DLP techniques are an effective and minimally invasive procedure for IH in patients with PHACES, in consideration of the multiple lesions to treat, of the necessity of multiple interventions and the higher compliance of the patients.

  6. Ultrasound-guided interstitial laser photocoagulation of an autonomous thyroid nodule

    DEFF Research Database (Denmark)

    Døssing, Helle; Bennedbaek, Finn Noe; Hegedüs, Laszlo

    2003-01-01

    Radioiodine ((131)I) and surgery are the standard therapeutic options for the solitary autonomous thyroid nodule (AFTN). Percutaneous ethanol injection (PEI) has proven to be an effective technique and possible alternative to the conventional treatment options. However, PEI is not devoid of side.......9 mL (40% reduction) without further alterations during an additional 9 months of follow-up. Side effects were transient thyrotoxicosis and local pain as seen with PEI. To our knowledge, this is the first reported case of ILP used in a patient with a pretoxic thyroid nodule. US-guided thermic tissue...

  7. Argon metastable dynamics and lifetimes in a direct current microdischarge

    Science.gov (United States)

    Stefanović, Ilija; Kuschel, Thomas; Schröter, Sandra; Böke, Marc

    2014-09-01

    In this paper we study the properties of a pulsed dc microdischarge with the continuous flow of argon. Argon metastable lifetimes are measured by tunable diode laser absorption spectroscopy (TDLAS) and are compared with calculated values which yield information about excitation and de-excitation processes. By increasing the gas flow-rate about 5 times from 10 to 50 sccm, the Arm lifetime increases from 1 to 5 μs due to the reduction of metastable quenching with gas impurities. Optical emission spectroscopy reveals nitrogen and water molecules as the main gas impurities. The estimated N2 density [N2] = 0.1% is too low to explain the measured metastable lifetimes. Water impurity was found to be the main de-excitation source of argon metastable atoms due to high quenching coefficients. The water impurity level of [H2O] = 0.15% to 1% is sufficient to bring calculated metastable lifetimes in line with experiments. The maximum value of water content in the discharge compared to the argon atoms is estimated to approximately 6%, due to the large surface to volume ratio of the microdischarge. The current pulse releases the water molecules from the electrode surface and they are either re-adsorbed in the time between 0.4 ms for [H2O] = 1% and 2.6 ms for [H2O] = 0.15% or pumped out of the discharge with the speed equal to the gas flow-rate. Depending on its partial pressure, the water impurity re-adsorption time is of the order of magnitude or less then the argon gas residence time.

  8. Miniaturized high-resolution wide-field contact lens for panretinal photocoagulation

    Directory of Open Access Journals (Sweden)

    Koushan K

    2014-04-01

    Full Text Available Keyvan Koushan, KV Chalam Department of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL, USA Background and objective: We describe a miniaturized lightweight high-refractive-index panretinal contact lens for diagnostic and therapeutic visualization of the peripheral retina. Instrument design: The miniaturized high-resolution wide-field contact lens includes three optical elements in a light (15 g and miniaturized (16 mm footplate, 24 mm external aperture, and 21 mm vertical height casing contributing to a total dioptric power of +171 diopters. This lens provides up to 165° visualization of the retina for diagnostic and therapeutic applications while allowing easier placement due to its miniaturization. Conclusion: This new lens (50% lighter and 89% smaller improves upon earlier contact lenses for visualization of the peripheral retina. Keywords: contact lens, panretinal photocoagulation, retinal examination, peripheral retina, high resolution view, wide-angle lens, lens

  9. Pulse Compression by Filamentation in Argon with an Acoustic Optical Programmable Dispersive Filter for Predispersion Compensation

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Wei; JIANG Yong-Liang; LENG Yu-Xin; LIU Jun; GE Xiao-Chun; LI Ru-Xin; XU Zhi-Zhan

    2006-01-01

    @@ We have experimentally demonstrated pulses 0.4 mJ in duration smaller than 12 fs with an excellent spatial beam profile by self-guided propagation in argon. The original 52fs pulses from the chirped pulsed amplification laser system are first precompressed to 32 fs by inserting an acoustic optical programmable dispersive filter instrument into the laser system for spectrum reshaping and dispersion compensation, and the pulse spectrum is subsequently broadened by filamentation in an argon cell. By using chirped mirrors for post-dispersion compensation, the pulses are successfully compressed to smaller than 12fs.

  10. Laser-Based Strategies to Treat Diabetic Macular Edema: History and New Promising Therapies

    Directory of Open Access Journals (Sweden)

    Young Gun Park

    2014-01-01

    Full Text Available Diabetic macular edema (DME is the main cause of visual impairment in diabetic patients. The management of DME is complex and often various treatment approaches are needed. At the present time, despite the enthusiasm for evaluating several new treatments for DME, including the intravitreal pharmacologic therapies (e.g., corticosteroids and anti-VEGF drugs, laser photocoagulation still remains the current standard in DME. The purpose of this review is to update our knowledge on laser photocoagulation for DME and describe the developments in laser systems. And we will also discuss the new laser techniques and review the latest results including benefits of combined therapy. In this paper, we briefly summarize the major laser therapeutics for the treatment of diabetic macular edema and allude to some future promising laser therapies.

  11. Pain and accuracy of focal laser treatment for diabetic macular edema using a retinal navigated laser (Navilas®)

    OpenAIRE

    Kampik A; Haritoglou C; Lang J; Liegl RG; Seidensticker F; Cserhati S; Cheuteu RE; Kernt M; Ulbig MW; Neubauer AS

    2012-01-01

    Marcus Kernt*, Raoul E Cheuteu*, Sarah Cserhati, Florian Seidensticker, Raffael G Liegl, Julian Lang, Christos Haritoglou, Anselm Kampik, Michael W Ulbig, Aljoscha S Neubauer Department of Ophthalmology, Ludwig Maximilian University of Munich, Germany*These authors contributed equally to this studyAim: To investigate treatment-related pain and the accuracy of navigated laser photocoagulation in the treatment of clinically significant macular edema.Methods: Focal laser treatment of diabetic ma...

  12. Beneficial effect of combined aspiration and interstitial laser therapy in patients with benign cystic thyroid nodules

    DEFF Research Database (Denmark)

    Døssing, H; Bennedbaek, F N; Hegedüs, L

    2006-01-01

    The aim of this study was to evaluate the effect of combined cyst aspiration and ultrasound-guided interstitial laser photocoagulation (ILP) on recurrence rate and the volume of benign cystic thyroid nodules. 10 euthyroid outpatients with a solitary and cytologically benign partially cystic thyroid...

  13. Composing Experimental Environment of PRIDE Argon cell

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Seonho; Jang, Yongkuk; Cho, Il Je [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In PRIDE depleted Uranium feed material and a depleted Uranium mixed with some surrogate material are used for performing engineering scale Pyroprocessing. PRIDE has to maintain inert atmosphere because of the characteristic of Electrolytic Reduction technology, Electro refining technology, Electrowinning technology. The impurity concentration of the Argon cell has to be under 50 ppm(Oxygen, moisture). Atmospheric pressure changes and temperature changes can affect the Argon cell's impurity concentration. In this paper, how to compose the Argon cell impurity concentration under 50 ppm to make the exact optimal experimental environment(Oxygen, moisture) will be introduced. Composing the exact optimal experimental environment by supplying Argon gas have been introduced in this paper. Continuously supplying Argon gas which is heavier than the Oxygen through the bottom of the Argon cell the oxygen eventually discharged through the high vent fan and lower the impurity concentration of Oxygen.

  14. MeV Argon ion beam generation with narrow energy spread

    CERN Document Server

    Xu, Jiancai; Shen, Baifei; Zhang, Hui; Li, Shun; Yu, Yong; Li, Jinfeng; Lu, Xiaoming; Wang, Cheng; Wang, Xinliang; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2016-01-01

    Laser driven particle acceleration has shown remarkable progresses in generating multi-GeV electron bunches and 10s of MeV ion beams based on high-power laser facilities. Intense laser pulse offers the acceleration field of 1012 Volt per meter, several orders of magnitude larger than that in conventional accelerators, enabling compact devices. Here we report that a highly-collimated argon ion beam with narrow energy spread is produced by irradiating a 45-fs fully-relativistic laser pulse onto an argon cluster target. The highly-charged (Argon ion with charge state of 16+) heavy ion beam has a minimum absolute energy spread of 0.19 MeV per nucleon at the energy peak of 0.39 MeV per nucleon. we identify a novel scheme from particle-in-cell simulations that greatly reduces the beam energy spread. The laser-driven intense plasma wakefield has a strong modulation on the ion beam in a way that the low energy part is cut off. The pre-accelerated argon ion beam from Coulomb explosion thus becomes more mono-energetic ...

  15. Dermatological laser treatment

    International Nuclear Information System (INIS)

    The article reviews the different lasers used in dermatology. Special emphasis is placed on the treatment of naevus flammeus (''portwine stain'') where lasers are the treatment of choice. Argon laser and pulsed dye laser are the main lasers used in vascular skin diseases, and the article focuses on these two types. Copper-vapour laser, neodymium-YAG laser and CO2 laser are also presented. Information is provided about the availability of laser technology in the different health regions in Norway. 5 refs., 2 figs

  16. The laser in urology

    Science.gov (United States)

    Hofstetter, Alfons G.

    2002-10-01

    Laser is an acronym for a physical principle and means: Light Amplification by stimulated Emission of Radiation. This principle offers a lot of tissue/light effects caused by the parameters: power density/time and the special qualities of the laser light. Nowadays for diagnosis and therapy following lasers are used in urology: Krypton- and Dye-lasers as well as the Neodymium-YAG- (nd:YAG-), Holmium-YAG (Ho:YAG-), Diode-, Argon- and the CO2-lasers.

  17. VISUAL OUTCOME AFTER LASER PHOTO COAGULATION IN DIA BETIC RETINOPATHY

    Directory of Open Access Journals (Sweden)

    Tariq

    2013-03-01

    Full Text Available ABSTRACT: PURPOSE: To evaluate the visual outcome after laser photocoag ulation in diabetic retinopathy. METHODS: One eye each of 100 patients were enrolled in our pro spective, randomized, clinical trial study with proliferative diabetic retinopathy/ maculopathy were assessed for visual outcome after treating them wit h laser photocoagulation. RESULTS: We observed that 62 (62% patients showed improvement by 1 or more lines on Snell’s chart, 26 (26% deteriorated from baseline visual acuity. The overall mean improved was 0.56 lines on Snell’s chart that is clinically significant. CONCLUSION: The results of present collection of hundred patients show a favourable influence of photo coagulation on the improvement and preservation of baseline visual acuity. Timely focal and grid laser photocoagulation helps in improving and stabilizing the visual acuity in patien ts with diabetic macular edema.

  18. Evaluation of RNFL thickness and serum cytokine levels after retinal photocoagulation combined with intravitreous Conbercept injection treatment of diabetic retinopathy

    Institute of Scientific and Technical Information of China (English)

    Luo Na

    2016-01-01

    Objective:To evaluate the effect of retinal photocoagulation combined with intravitreous Conbercept injection in RNFL thickness, serum cytokine levels and other aspects of diabetic retinopathy.Methods:A total of 92 patients with diabetic retinopathy (126 eyes) who received inpatient treatment in our hospital from December, 2013 to December 2015 were included in the study and divided into observation group 46 cases (62 eyes) and control group 46 cases (64 eyes) according to random number table, control group received retinal photocoagulation therapy alone, observation group received retinal photocoagulation combined with intravitreous Conbercept injection treatment, and then differences in RNFL thickness, hemodynamic indexes, serum levels of cytokines and others were compared between two groups after treatment.Results: Average RNFL thickness of inner optic disc top, bottom, bitamporal and nasal ring area as well as the average full-cycle 360° RNFL thickness of observation group after treatment was less than those of control group; PSV and EDV values of CRA were higher than those of control group while RI value was lower than that of control group, and PSV, EDV and RI values of CRV were lower than those of control group; serumβ2-GPⅠ, Hcy, VEGF and SDF-1 levels were lower than those of control group while C-peptide and APN levels were higher than those of control group.Conclusion: Retinal photocoagulation combined with intravitreous Conbercept injection can significantly reduce the RNFL thickness of the patients with diabetic retinopathy and optimize the retinal hemodynamic status, and helps to improve patients’ overall conditions.

  19. Oral vascular malformations: laser treatment and management

    Science.gov (United States)

    Romeo, U.; Rocchetti, F.; Gaimari, G.; Tenore, G.; Palaia, G.; Lo Giudice, G.

    2016-03-01

    Vascular malformations are a very heterogeneous group of circulatory system's diseases that can involve different kind of vessels: arterial, venous or lymphatic ones. Many treatments, such as conventional surgery, embolization, steroid therapy and laser therapy, are available for vascular lesions. The laser approach relies more therapeutic techniques: the transmucosal thermophotocoagulation, intralesional photocoagulation, the excisional biopsy. Today laser is demonstrated to be the gold standard technique to treat vascular lesions that allows a safe and efficient treatment and a lower post-operative healing time. The only disadvantage is the risk of carbonization that could be avoided by using the multiple-spot single pulsed wave technique.

  20. Tin LPP plasma control in the argon cusp source

    Science.gov (United States)

    McGeoch, Malcolm W.

    2016-03-01

    The argon cusp plasma has been introduced [1,2] for 500W class tin LPP exhaust control in view of its high power handling, predicted low tin back-scatter from a beam dump, and avoidance of hydrogen usage. The physics of tin ion control by a plasma is first discussed. Experimentally, cusp stability and exhaust disc geometry have previously been proved at full scale [2], the equivalent of 300W-500W usable EUV. Here we verify operation of the plasma barrier that maintains a high argon density next to the collector, for its protection, and a low density in the long path toward the intermediate focus, for efficiency. A pressure differential of 2Pa has been demonstrated in initial work. Other aspects of tin LPP plasma control by the cusp have now been demonstrated using tin ions from a low Hz 130mJ CO2 laser pulse onto a solid tin surface at the cusp center. Plasma is rejected at the design to match a specified exhaust power is discussed. In view of this work, argon cusp exhaust control appears to be very promising for 500W class tin LPP sources.

  1. The influence of C2H2 and dust formation on the time dependence of metastable argon density in pulsed plasmas

    OpenAIRE

    Stefanovic, Ilija; Sadeghi, Nader; Winter, Jörg

    2010-01-01

    Abstract Diode laser absorption at 772.38 nm is used to measure the time resolved density of Ar*(3 P 2) metastable atoms in a capacitively coupled radio-frequency (RF) discharge running in argon/acetylene mixture at 0.1 mbar. The RF power is pulsed at 100 Hz and the density of Ar*(3 P 2) atoms in the 5 ms ON time and in the afterglow are recorded. Different plasma conditions, namely: 1) pure argon, 2) argon + 7% acetylene before powder formation, 3) argon + 7% acetylene after dust particle...

  2. Lasers in Cardiovascular Surgery—Current Status

    OpenAIRE

    Hunter, John G.; Dixon, John A.

    1985-01-01

    The argon, carbon dioxide and neodymium-YAG lasers have been proposed as effective instruments for surgical procedures of the intact cardiovascular system. While argon and CO2 lasers cause superficial (0 to 1 mm) thermal injury, the Nd:YAG laser is better suited for effecting deep thermal necrosis (3 to 4 mm). Microsurgical vessel anastomoses can be done by “tissue welding” with any of the three clinical lasers. Myocardial revascularization may be accomplished by drilling “neocapillaries” in ...

  3. Transition probabilities for argon I

    International Nuclear Information System (INIS)

    Transition probabilities for ArI lines have been calculated on the basis of the (j,k)-coupling scheme for more than 16000 spectral lines belonging to the transition arrays 4s-np (n=4 to n=9), 5s-np (n=5 to n=9), 6s-np (n=6 to n=9), 7s-np (n=8 to n=9), 4p-ns (n=5 to n=10), 5p-ns (n=6 to n=9), 6p-ns (n=7 to n=8), 4p-nd (n=3 to n=9), 5p-nd (n=4 to n=9), 3d-np (n=5 to n=9), 4d-np (n=6 to n=9), 5d-np (n=7 to n=9), 3d-nf (n=4 to n=9), 4d-nf (n=4 to n=9), 5d-nf (n=5 to n=9), 4f-nd (n=5 to n=9) 5f-nd (n=6 to n=9), 4f-ng (n=5 to n=9), 5f-ng (n=6 to n=9). Inso far as values by other authors exist, comparison is made with these values. It turns out that the results obtained in (j,k)-coupling are close to those obtained in intermediate coupling except for intercombination lines. For high principal and/or orbital quantum numbers the transition probabilities for a multiplet approach those of the corresponding transitions in atomic hydrogen. The calculated values are applied to construct a simplified argon-atom model, which reflects the real transition properties and which allows simplified but realistic non-equilibrium calculations for argon plasmas which deviate from local thermodynamic equilibrium (LTE)

  4. A 20-Liter Test Stand with Gas Purification for Liquid Argon Research

    CERN Document Server

    Li, Yichen; Tang, Wei; Joshi, Jyoti; Qian, Xin; Diwan, Milind; Kettell, Steve; Morse, William; Rao, Triveni; Stewart, James; Tsang, Thomas; Zhang, Lige

    2016-01-01

    We describe the design of a 20-liter test stand constructed to study fundamental properties of liquid argon (LAr). This system utilizes a simple, cost-effective gas argon (GAr) purification to achieve ultra-high purity, which is necessary to study electron transport properties in LAr. An electron drift stack with up to 25 cm length is constructed to study electron drift, diffusion, and attachment at various electric fields. A gold photocathode and a pulsed laser are used as a bright electron source. The operational performance of this system is reported.

  5. Opacity of Shock-Generated Argon Plasmas

    Institute of Scientific and Technical Information of China (English)

    王藩侯; 陈敬平; 周显明; 李西军; 经福谦; 孟续军; 孙永盛

    2001-01-01

    Argon plasmas with uniform density and temperature are generated by a planar shock wave through argon gas. The opacities of argon plasma, covering the thermodynamic states at temperatures of 1.4-2.2eV and in densities of 0.0083- 0.015 g/cm3, are investigated by measuring the emitted radiance versus time at several visible wavelengths. Comparison of the measured opacities with those calculated demonstrates that the average atom model can be used well to describe the essential transport behaviour of photons in argon plasma under the abovementioned thermodynamic condition. A simplified and self-consistent method to deduce the reflectivity R(λ) at the baseplate surface is applied. It demonstrates that the values of R(λ) are all around 0.4 in the experiments, which are basically in agreement with those given by Erskine previously (1994 J. Quant. Spectrosc. Radiat.Transfer 51 97).

  6. Status and perspecitves of liquid argon calorimeters

    International Nuclear Information System (INIS)

    The status of liquid argon calorimeters is reviewed, and experience obtained with these devices is described. Future perspectives of the liquid ionization chamber technique in calorimetry are also discussed. (orig.)

  7. Argon plasma irradiation of polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Slepicka, P., E-mail: petr.slepicka@vscht.c [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic); Vasina, A. [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic); Kolska, Z. [J.E. Purkyne University, Department of Chemistry, 40096 Usti Nad Labem (Czech Republic); Luxbacher, T. [Anton Paar GmbH, 8054 Graz (Austria); Malinsky, P.; Mackova, A. [Nuclear Physics Institute of Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic)

    2010-06-15

    Polypropylene samples were exposed to argon plasma discharge and the changes of the PP surface properties were studied by different methods. Surface wettability was derived from contact angle measured by standard goniometry and chemical structure of the plasma modified PP was studied using X-ray photoelectron spectroscopy (XPS) and by Rutherford backscattering spectroscopy (RBS), surface morphology and roughness of samples using AFM. Zeta potential of pristine and modified PP was determined with the SurPASS. The presence of incorporated oxygen in the PP surface layer, about 60 nm thick, was observed in RBS spectra. Oxygen concentration is a decreasing function of the depth. With progressing aging time the oxygen concentration on the PP surface decreases. Plasma treatment results in a rapid decrease of the contact angle, which increases again with increasing aging time. In XPS measurement the oxygen containing structures, created by the plasma treatment, were found on the very surface of the modified PP and the zeta potential being changed too. The significant difference in zeta potential between pristine and plasma treated PP clearly indicates that the plasma treatment leads to a more hydrophilic PP surface.

  8. Negative corona current pulses in argon and in mixture argon with SF6

    International Nuclear Information System (INIS)

    Waveforms of the first negative current pulses in a short negative point-to plane gap in pure argon and argon with SF6 admixture have been investigated with a nanosecond time resolution at a gas pressure 50 kPa as a function of applied gap voltage and content of SF6 in the mixture. We have made an attempt to explain the differences in the discharge development in pure argon and in argon with admixture of SF6 based on the observed changes of the pulse shape. The experimental results obtained will be discussed in context with existing computer simulation models (Authors)

  9. Measurements on scintillation light from liquid argon

    International Nuclear Information System (INIS)

    It is shown that an argon calorimeter can operate as a scintillation detector, provided that xenon is added. With the addition of 170 ppm xenon a light yield of 70% has been obtained. In addition the light yield is determined under influence of an electric field, from differently ionising particles and by the use of aluminium mirrors acting as light guides. Finally first measurements with a photomultiplier working at liquid argon temperatures are reported. (orig.)

  10. Argon clusters embedded in helium nanodroplets.

    Science.gov (United States)

    da Silva, Filipe Ferreira; Bartl, Peter; Denifl, Stephan; Echt, Olof; Märk, Tilmann D; Scheier, Paul

    2009-11-14

    Electron impact ionization of argon clusters embedded in helium droplets is investigated. Superior mass resolution makes it possible to distinguish between nominally isobaric cluster ions. An abundance maximum for ArHe(12)(+) is unambiguously confirmed; the spectra also prove the formation of Ar(2)He(n)(+) complexes that had been claimed to fragment into pure Ar(2)(+). Distributions of larger argon cluster ions containing up to 60 atoms closely resemble distributions observed upon electron impact or photoionization of bare argon clusters; caging and evaporative cooling provided by the helium matrix do not suffice to quench fragmentation of the nascent argon cluster ions. Intriguing abundance anomalies are observed in distributions of argon cluster ions that contain water, nitrogen or oxygen impurities. The strong abundance of Ar(55)H(2)O(+), Ar(54)O(2)(+) and Ar(54)N(2)(+) contrasts with the virtual absence of slightly larger cluster ions containing the corresponding impurities. The features are probably related to enhanced cluster ion stability upon closure of the second icosahedral shell but the difference in magic numbers (54 versus 55) and the well-known reactivity of charged argon-nitrogen complexes suggest structural differences. PMID:19851558

  11. Potassium-argon/argon-40-argon-39 geochronology of Cenozoic alkali basalts from the South China Sea

    Institute of Scientific and Technical Information of China (English)

    YAN Quanshu; SHI Xuefa; YANG Yaomin; WANG Kunshan

    2008-01-01

    Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea,the characteristics of volcanic activi-ty of the South China Sea after spreading were studied.The potassium - argon ages of eight alkali basalt samples from the South China Sea,and the argon - argon ages of two samples among them are reported.Apparent ages of the whole rock are 3.80 to 7.91 Ma with an average value of 5.43 Ma (potassium- argon,whole rock),and there is little difference among samples at the same location,e.g.,4.76~5.78 Ma for location S04-12.The argon - argon ages for the two samples are 6.06 and 4.71 Ma,which lie within the age scope of potassium - argon method.The dating results indicate that rock-forming age is from late Miocene to Pli-ocene,which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea.Volcanic activities occur after the cessation of spreading of the South China Sea,which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea.These dating results,combined with geochemical characteristics of these basalts,the published chronological data for the South China Sea and its adjacent regions,and the updated geophysical data near Hainan Island,suggest that after the cessation of spreading of the South China Sea,there occur widely distributing magmatic activities which primarily is alkali basalt,and the volcanic activity continues to Quaternary.The activity may be relative to Hainan mantle plume originated from core/mantle boundary.

  12. Argon Collection And Purification For Proliferation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-09

    In order to determine whether a seismic event was a declared/undeclared underground nuclear weapon test, environmental samples must be taken and analyzed for signatures that are unique to a nuclear explosion. These signatures are either particles or gases. Particle samples are routinely taken and analyzed under the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) verification regime as well as by individual countries. Gas samples are analyzed for signature gases, especially radioactive xenon. Underground nuclear tests also produce radioactive argon, but that signature is not well monitored. A radioactive argon signature, along with other signatures, can more conclusively determine whether an event was a nuclear test. This project has developed capabilities for collecting and purifying argon samples for ultra-low-background proportional counting. SRNL has developed a continuous gas enrichment system that produces an output stream containing 97% argon from whole air using adsorbent separation technology (the flow diagram for the system is shown in the figure). The vacuum swing adsorption (VSA) enrichment system is easily scalable to produce ten liters or more of 97% argon within twelve hours. A gas chromatographic separation using a column of modified hydrogen mordenite molecular sieve has been developed that can further purify the sample to better than 99% purity after separation from the helium carrier gas. The combination of these concentration and purification systems has the capability of being used for a field-deployable system for collecting argon samples suitable for ultra-low-background proportional counting for detecting nuclear detonations under the On-Site Inspection program of the CTBTO verification regime. The technology also has applications for the bulk argon separation from air for industrial purposes such as the semi-conductor industry.

  13. Laser therapy in plastic surgery: decolorization in port wine stains

    Science.gov (United States)

    Peszynski-Drews, Cezary; Wolf, Leszek

    1996-03-01

    For the first time laserotherapy is described as a method of port wine stain decolorization in plastic surgery. The authors present their 20-year experience in the treatment of port wine stains with the argon laser and dye laser.

  14. Long term refractive and structural outcome following laser treatment for zone 1 aggressive posterior retinopathy of prematurity

    OpenAIRE

    Parag K Shah; Ramakrishnan, Minu; Sadat, Bani; Bachu, Sandeep; V Narendran; Kalpana, N.

    2014-01-01

    Aim: To report the long term refractive, visual and structural outcome post-laser for zone 1 aggressive posterior retinopathy of prematurity (AP-ROP). Materials and Methods: A retrospective analysis was performed of refractive status of premature infants with zone 1 AP-ROP who underwent laser photocoagulation from 2002 to 2007 and followed up till 2013. Once the disease regressed, children were followed up six monthly with detailed examination regarding fixation pattern, ocular motility, nyst...

  15. Long term refractive and structural outcome following laser treatment for zone 1 aggressive posterior retinopathy of prematurity

    OpenAIRE

    Parag K Shah; Minu Ramakrishnan; Bani Sadat; Sandeep Bachu; V Narendran; Kalpana, N.

    2014-01-01

    Aim: To report the long term refractive, visual and structural outcome post-laser for zone 1 aggressive posterior retinopathy of prematurity (AP-ROP). Materials and Methods: A retrospective analysis was performed of refractive status of premature infants with zone 1 AP-ROP who underwent laser photocoagulation from 2002 to 2007 and followed up till 2013. Once the disease regressed, children were followed up six monthly with detailed examination regarding fixation pattern, ocular motility, ...

  16. Attenuation of vacuum ultraviolet light in liquid argon

    CERN Document Server

    Neumeier, A; Oberauer, L; Potzel, W; Schönert, S; Dandl, T; Heindl, T; Ulrich, A; Wieser, J

    2015-01-01

    The transmission of liquid argon has been measured, wavelength resolved, for a wavelength interval from 118 to 250 nm. The wavelength dependent attenuation length is presented for pure argon. It is shown that no universal wavelength independent attenuation length can be assigned to liquid argon for its own fluorescence light due to the interplay between the wavelength dependent emission and absorption. A decreasing transmission is observed below 130 nm in both chemically cleaned and distilled liquid argon and assigned to absorption by the analogue of the first argon excimer continuum. For not perfectly cleaned argon a strong influence of impurities on the transmission is observed. Two strong absorption bands at 126.5 and 141.0 nm with approximately 2 and 4 nm width, respectively, are assigned to traces of xenon in argon. A broad absorption region below 180 nm is found for unpurified argon and tentatively attributed to the presence of water in the argon sample.

  17. Cutaneous Laser Therapy

    OpenAIRE

    John A. Dixon; Gilbertson, Jeffrey J.

    1985-01-01

    The carbon dioxide laser is useful for vaporizing lesions and applying incisions, the argon laser coagulates superficial vascular lesions and the neodymium-YAG laser is used for large vascular and more deeply situated lesions. Many patients with port-wine stains have been treated with excellent to poor results, major problems consisting of incomplete color removal and hypertrophic scarring (occurring in 4% to 23% of cases). While results are imperfect, patients are satisfied with the improvem...

  18. Lasers in Ophthalmology

    Institute of Scientific and Technical Information of China (English)

    1992-01-01

    In recent years,lasers have entered every fieldof medicine and especially so in ophthalmol-ogy.The scientific basis of lasers in ophthal-mology is based on three mechanisms:1.Photothermal effectLasers:argon,krypton,dye and diodeA thermal effect is generated when laserenergy is absorbed by pigment leading to in-creased vibration and therefore heat content.A

  19. Characterization of SF6/Argon Plasmas for Microelectronics Applications; TOPICAL

    International Nuclear Information System (INIS)

    This report documents measurements in inductively driven plasmas containing SF(sub 6)/Argon gas mixtures. The data in this report is presented in a series of appendices with a minimum of interpretation. During the course of this work we investigated: the electron and negative ion density using microwave interferometry and laser photodetachment; the optical emission; plasma species using mass spectrometry, and the ion energy distributions at the surface of the rf biased electrode in several configurations. The goal of this work was to assemble a consistent set of data to understand the important chemical mechanisms in SF(sub 6) based processing of materials and to validate models of the gas and surface processes

  20. Attosecond Coherent Control of Single and Double Photoionization in Argon.

    Science.gov (United States)

    Hogle, C W; Tong, X M; Martin, L; Murnane, M M; Kapteyn, H C; Ranitovic, P

    2015-10-23

    Ultrafast high harmonic beams provide new opportunities for coherently controlling excitation and ionization processes in atoms, molecules, and materials on attosecond time scales by employing multiphoton two-pathway electron-wave-packet quantum interferences. Here we use spectrally tailored and frequency tuned vacuum and extreme ultraviolet harmonic combs, together with two phase-locked infrared laser fields, to show how the total single and double photoionization yields of argon can be coherently modulated by controlling the relative phases of both optical and electronic-wave-packet quantum interferences. This Letter is the first to apply quantum control techniques to double photoionization, which is a fundamental process where a single, high-energy photon ionizes two electrons simultaneously from an atom. PMID:26551112

  1. Electron-ion recombination study in argon at atmospheric pressure

    International Nuclear Information System (INIS)

    This study deals with a wall-stabilized arc burning in argon at atmospheric pressure. A transient mode is obtained using a fast thyristor connected to the electrodes, which short-circuits the discharge. By means of two wavelengths laser interferometry and spectroscopy measurements we have determined the temporal changes of the electron density, ground state atom density and excited atom density. We have shown that, when the electric field is suppressed, the electron temperature rapidly decreases to the gas temperature before changing electron and atom densities. This phenomenon is applied to determine the gas temperature and to evaluate the role played by ionization in electron density balance. The coefficients of ambipolar diffusion, ionization and recombination and an apparent recombination coefficient are determined versus electron temperature and compared with theoretical values

  2. Scintillation efficiency of liquid argon in low energy neutron-argon scattering

    International Nuclear Information System (INIS)

    Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field

  3. Scintillation efficiency of liquid argon in low energy neutron-argon scattering

    CERN Document Server

    Creus, W; Amsler, C; Ferella, A D; Rochet, J; Scotto-Lavina, L; Walter, M

    2015-01-01

    Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field.

  4. Comparison of photosensitivity in germanium doped silica fibers using 244 nm and 266 nm continuous wave lasers

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo; Varming, Poul; Liu, B.;

    2001-01-01

    Diode pumped continuous-wave UV lasers offer an interesting alternative to frequency doubled argon-ion lasers. We report the first photosensitivity comparison using these lasers on deuterium loaded standard telecommunication fibers and unloaded experimental fibers....

  5. Photoablation of ocular melanoma with a high-powered argon endolaser.

    Science.gov (United States)

    Jaffe, G J; Mieler, W F; Burke, J M; Williams, G A

    1989-01-01

    We studied the use of a 15-W argon blue-green laser in the treatment of choroidal melanoma in a rabbit model. Greene melanoma cells were used to produce 2- to 4-mm thick tumors posteriorly in the suprachoroidal space in pigmented rabbits. Endophotocoagulation delivered through a 600-micron fiberoptic probe was performed to ablate the tumor tissue and a surrounding margin of normal tissue. A vitreous cutter was used simultaneously to remove liberated necrotic debris. The effect of the laser on tumor and normal ocular tissue was evaluated by light microscopy and the extent of the proliferative response by tritiated thymidine radioautography. Application of 100 to 400 pulses of laser energy using treatment parameters of 12 to 14 W of power and 0.1-s pulses resulted in complete ablation of melanoma tissue, overlying retina, and choroid. There was no substantial intraoperative or postoperative hemorrhage. Material liberated during the laser treatment was found to be nonviable. The effect of the laser on tissue appeared localized to within approximately 1.25 mm of the margin of the central lesion. The high-energy argon laser seems to offer a means of effectively ablating melanoma tissue via an internal resection approach. PMID:2910269

  6. Contraction ionization waves in the argon contracted discharge

    International Nuclear Information System (INIS)

    An investigation of ionization waves in the argon contracted discharge and a definition of their arising propagation mechanism accounting for the specificity of elementary pocesses characteristic of argon are presented. (author)

  7. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  8. Antiapoptotic activity of argon and xenon.

    Science.gov (United States)

    Spaggiari, Sabrina; Kepp, Oliver; Rello-Varona, Santiago; Chaba, Kariman; Adjemian, Sandy; Pype, Jan; Galluzzi, Lorenzo; Lemaire, Marc; Kroemer, Guido

    2013-08-15

    Although chemically non-reactive, inert noble gases may influence multiple physiological and pathological processes via hitherto uncharacterized physical effects. Here we report a cell-based detection system for assessing the effects of pre-defined gas mixtures on the induction of apoptotic cell death. In this setting, the conventional atmosphere for cell culture was substituted with gas combinations, including the same amount of oxygen (20%) and carbon dioxide (5%) but 75% helium, neon, argon, krypton, or xenon instead of nitrogen. The replacement of nitrogen with noble gases per se had no effects on the viability of cultured human osteosarcoma cells in vitro. Conversely, argon and xenon (but not helium, neon, and krypton) significantly limited cell loss induced by the broad-spectrum tyrosine kinase inhibitor staurosporine, the DNA-damaging agent mitoxantrone and several mitochondrial toxins. Such cytoprotective effects were coupled to the maintenance of mitochondrial integrity, as demonstrated by means of a mitochondrial transmembrane potential-sensitive dye and by assessing the release of cytochrome c into the cytosol. In line with this notion, argon and xenon inhibited the apoptotic activation of caspase-3, as determined by immunofluorescence microscopy coupled to automated image analysis. The antiapoptotic activity of argon and xenon may explain their clinically relevant cytoprotective effects. PMID:23907115

  9. Keeping argon under a graphene lid-Argon intercalation between graphene and nickel(111)

    Science.gov (United States)

    Späth, Florian; Gotterbarm, Karin; Amende, Max; Bauer, Udo; Gleichweit, Christoph; Höfert, Oliver; Steinrück, Hans-Peter; Papp, Christian

    2016-01-01

    We report on the intercalation of graphene grown on a Ni(111) crystal with argon. Argon is implanted in the Ni(111) crystal by ion bombardment before graphene growth, and diffuses to the surface during the growth of graphene at elevated temperatures. Graphene acts as an atomically thin barrier and keeps the argon underneath. We investigated this system with high resolution X-ray photoelectron spectroscopy. From our experiments we determined the mean quantities of argon under graphene. From our analysis, a simple model to determine the pressure under the graphene layer is presented. In our measurements, we find an increased thermal stability of the intercalated graphene as compared to non-intercalated graphene on Ni(111).

  10. Effect of Cervical Length Recovery after Laser Surgery for Twin-Twin Transfusion Syndrome

    OpenAIRE

    Finneran, Matthew; Temming, Lorene; Templin, Megan; Stephenson, Courtney

    2016-01-01

    Objective To evaluate the impact of polyhydramnios on preoperative cervical length and whether cervical length recovery after amnioreduction during selective fetoscopic laser photocoagulation (SFLP) is associated with a greater gestational age at delivery in pregnancies complicated by twin-twin transfusion syndrome (TTTS). Methods Retrospective study of 50 pregnancies complicated by TTTS treated with SFLP between March 2010 and July 2014 at a single center. Preoperative maximum vertical pocke...

  11. Flow Parameters of Argon plasma Discharge

    International Nuclear Information System (INIS)

    Owing to the viscosity, the plasma will be adhering to the inner surface of the outer electrode and outer surface of the inner one. As result that the discharge will be eroding the walls of coaxial system. The thickness of the boundary layer near the walls has been estimated at different positions from the breech of coaxial plasma gun. It is found that the thickness of layer 0.008 cm at the end of inner electrode (17 cm). A coaxial plasma gun device is operated in argon gas at ambient pressure 0.6 Torr and discharge voltage about 10 KV. The electron temperature of argon discharge has been determined by using spectroscopic technique. It is found that kTe=3.4 eV. By knowing the thickness of the boundary layer, the density can be determined. The Reynolds number R=105 and Mach number M=5 i.e. the flow is compressible and hypersonic

  12. Explanation of the memory effect in argon

    Directory of Open Access Journals (Sweden)

    Marković Vidosav

    2005-01-01

    Full Text Available Memory effect - the long time variation of the electrical breakdown time delay on the relaxation time td (τ was observed in argon 24 hours after relaxation times and explained by the long-lived metastable states remaining from the preceding glow. However, the quenching processes reducing the effective lifetime of metastable states several orders of magnitude below that relevant for the time scale of observation were neglected. By applying approximate gas phase models it was found that the early afterglow kinetics up to hundreds of milliseconds is dominated by the decay of molecular argon ions Ar2+ and the approximate value of their ambipolar diffusion coefficient is determined. After that, nitrogen atoms present as impurities and recombined on the cathode surface and/or field emission determine the breakdown time delay down to the cosmic rays and natural radioactivity level.

  13. Anatomy of an Inversion - Argon Isotopes

    Science.gov (United States)

    Zamick, L.; Sharon, Y. Y.; Robinson, S. J. Q.

    2012-02-01

    Two different interactions give similar results for excitation energies and g factors of 2+1 states for most even-even argon isotopes except 46Ar. This is explained in terms of an inversion in J = ½+ and levels in 47K which is successfully obtained by one of the interactions but not the other. This example shows the possible dangers of nuclear astrophysics extrapolations.

  14. Visual Outcomes of Pan-retinal Photocoagulation in Diabetic Retinopathy at One-year Follow-up and Associated Risk Factors

    OpenAIRE

    Rema Mohan; Sujatha Purushothaman; Pradeepa Rajendra

    2005-01-01

    Purpose: To assess the visual outcomes at one-year follow-up after pan-retinal photocoagulation (PRP) in type 2 diabetes mellitus subjects with proliferative diabetic retinopathy (PDR) and associated risk factors. Materials and Methods: A retrospective study, using data from medical records of 5000 Type 2 diabetic patients who underwent a retinal examination between 1995 and 1999 at a diabetic centre. Ocular, clinical and biochemical parameters were assessed at baseline and at one-year fol...

  15. 胎儿镜下胎盘血管交通支凝固术治疗双胎输血综合征6例临床分析%Retrospective analysis of fetoscopic photocoagulation of communicating placental vessels of twin-twin transfusion syndrome

    Institute of Scientific and Technical Information of China (English)

    李俊男; 王琳; 葛晓冬; 张晓航; 蔡萍; 梁志清; 陈功立; 管唯靓; 胡华; 陈诚; 蒋凤; 余关佳; 常青

    2009-01-01

    目的 探讨胎儿镜下胎盘血管交通支凝同术(选择性或非选择性)治疗双胎输血综合征(twin-twin transfusionsyndrome,TTTS)对围生结局的影响.方法 6例TTTS接受胎儿镜下胎盘血管交通支凝固术治疗,在实时超声引导下,直径3 mm胎儿镜经孕妇腹壁进入羊水过多的受血儿羊膜腔,在胎儿镜下找到胎盘血管交通支,采用Nd:YAG激光光纤或双极电凝凝固血管交通支.结果 6位母亲均能耐受手术过程,没有严重的并发症发生.至少有1胎存活率50%(3/6),双胎儿存活率为33.33%(2/6),胎儿总存活率41.6%(5/12).结论 胎儿镜下胎盘血管交通支凝固术治疗,TTTS能提高围生儿的存活率.%Objective To investigate the effect of fetoscopic photocoagulation of communicating placental vessels in twin-twin transfusion syndrome (TITS) (selective or non-selective) on the perinatal outcomes. Methods Six cases of TTTS admitted in our department from Dee. 2006 to Jun. 2008 underwent fetoscopic photocoagulation of communicating vessels. Under direct real-time sonographic guidance, a 3-mm-diameter feto-scope was percutaneously inserted through the maternal abdominal wall into the amniotic cavity of the recipient twin. A eornbination of uhrasonographic and fetoscopie vision was used to identify the erossing vessels which were systematically coagulated using Nd:YAG laser fiber or bipolar eleetroeoagulation. Results All the 6 moth-ers tolerated the procedure without major complications. Two fetal survival rate was 33.33%. Gonclusion Feto-scopic photocoagulation of communicating placental vessels in TITS can effectively improve perinatal outcomes.

  16. Effects of metastable species in helium and argon atmospheric pressure plasma jets (APPJs) on inactivation of periodontopathogenic bacteria

    Science.gov (United States)

    Yoon, Sung-Young; Kim, Kyoung-Hwa; Seol, Yang-Jo; Kim, Su-Jeong; Bae, Byeongjun; Huh, Sung-Ryul; Kim, Gon-Ho

    2016-05-01

    The helium and argon have been widely used as discharge gases in atmospheric pressure plasma jets (APPJs) for bacteria inactivation. The APPJs show apparent different in bullet propagation speed and bacteria inactivation rate apparently vary with discharge gas species. This work shows that these two distinctive features of APPJs can be linked through one factor, the metastable energy level. The effects of helium and argon metastable species on APPJ discharge mechanism for reactive oxygen nitrogen species (RONS) generation in APPJs are investigated by experiments and numerical estimation. The discharge mechanism is investigated by using the bullet velocity from the electric field which is obtained with laser induced fluorescence (LIF) measurement. The measured electric field also applied on the estimation of RONS generation, as electron energy source term in numerical particle reaction. The estimated RONS number is verified by comparing NO and OH densities to the inactivation rate of periodontitis bacteria. The characteristic time for bacteria inactivation of the helium-APPJ was found to be 1.63 min., which is significantly less than that of the argon-APPJ, 12.1 min. In argon-APPJ, the argon metastable preserve the energy due to the lack of the Penning ionization. Thus the surface temperature increase is significantly higher than helium-APPJ case. It implies that the metastable energy plays important role in both of APPJ bullet propagation and bacteria inactivation mechanism.

  17. Laser in operative dentistry

    Directory of Open Access Journals (Sweden)

    E. Yasini

    1994-06-01

    Full Text Available Today laser has a lot of usage in medicine and dentistry. In the field of dentistry, laser is used in soft tissue surgery, sterilization of canals (in root canal therapy and in restorative dentistry laser is used for cavity preparation, caries removal, sealing the grooves (in preventive dentistry, etching enamel and dentin, composite polymerization and removal of tooth sensitivity. The use of Co2 lasers and Nd: YAG for cavity preparation, due to creating high heat causes darkness and cracks around the region of laser radiation. Also due to high temperature of these lasers, pulp damage is inevitable. So today, by using the Excimer laser especially the argon floride type with a wavelength of 193 nm, the problem of heat stress have been solved, but the use of lasers in dentistry, especially for cavity preparation needs more researches and evaluations.

  18. Development of a low-cost inductively coupled argon plasma

    International Nuclear Information System (INIS)

    The aim of this investigation is to drastically reduce running costs of an inductively coupled plasma. This is done by reducing the argon consumption from 20 l/min to about 1 l/min. First, a sample introduction system operating on 0.1 l/min of carrier argon is described. This system ensures a high ratio of plasma argon and carrier argon even at the low total argon consumptions intended. Next, the developed low consumption plasma is presented. In the proposed design, air is blown perpendicularly against the outside of the torch. A different coil has been developed to make air-cooling efficient. Preliminary data on coupling efficiency for the air-cooled plasma are presented. A similarly low argon consumption has been achieved with water as an external coolant medium. It is concluded that a cheaper alternative to the current ICP has become available. (Auth.)

  19. Study on tracheal intubation related severe subglottic stenosis under laryngeal mask by using holmium laser combined with argon plasma coagulation and cryotherapy through bronchoscopy%喉罩下经支气管镜钬激光联合氩气刀和二氧化碳冷冻治疗儿童获得性重度声门下狭窄

    Institute of Scientific and Technical Information of China (English)

    许煊; 祝彬; 石苗茜; 任海丽; 封志纯

    2015-01-01

    目的:探讨2例气管插管相关性重度声门下狭窄喉罩下支气管镜诊断及介入治疗的操作方法、有效性及安全性。方法2例男性患儿,年龄分别为4和11个月,因气管插管后出现脱机困难及呼吸困难,经CT及支气管镜检查,诊断为气管插管相关的重度声门下狭窄,在对家长进行详细告知支气管镜下介入手术不可预知情况并由家长签字同意后,遂对2例患儿进行经喉罩支气管镜下钬激光联合氩气刀和二氧化碳( CO2)冷冻治疗,分析患儿的临床资料、并发症及术后转归、随访情况。结果2例手术过程顺利,例1术后紧贴声门下的肉芽组织被完全清除,2例患儿声门下环形狭窄完全解除,治疗前呼吸道狭窄处周长约2.5 mm,治疗后,周长达5.2 mm,4.0 mm支气管镜进出无障碍,术后气管导管均成功拔除,呼吸困难均明显改善。2例患儿治疗后即刻、7 d、30 d和90 d镜下检查结果示狭窄处开放良好。术中有血氧饱和度下降及心率增快或减慢,暂停操作及恢复给氧后立即恢复,术中及术后未见异常血流动力学改变,2例目前仍在随访中。结论经喉罩钬激光、氩气刀及CO2冷冻治疗可用于后天性肉芽组织增生引起的声门下狭窄,方法安全、有效,近期效果显著,远期仍在进一步随访评估。%Objective To explore the operating methods,the effectiveness and safety for 2 cases of tracheal in-tubation related severe subglottic stenosis under laryngeal mask by using bronchoscopy in the diagnosis and interven-tional treatment. Methods Two male patients ( age at 4 and 11 months) both had difficulty breathing and weaning failure after endotracheal intubation,who were diagnosed with severe subglottic stenosis through CT and bronchoscopy examination. All parents signed their consent after being fully informed of treatment risks. Two cases were treated under bronchoscopic holmium laser combined with argon plasma coagulation and

  20. 喉罩下经支气管镜钬激光联合氩气刀和二氧化碳冷冻治疗儿童获得性重度声门下狭窄%Study on tracheal intubation related severe subglottic stenosis under laryngeal mask by using holmium laser combined with argon plasma coagulation and cryotherapy through bronchoscopy

    Institute of Scientific and Technical Information of China (English)

    许煊; 祝彬; 石苗茜; 任海丽; 封志纯

    2015-01-01

    目的:探讨2例气管插管相关性重度声门下狭窄喉罩下支气管镜诊断及介入治疗的操作方法、有效性及安全性。方法2例男性患儿,年龄分别为4和11个月,因气管插管后出现脱机困难及呼吸困难,经CT及支气管镜检查,诊断为气管插管相关的重度声门下狭窄,在对家长进行详细告知支气管镜下介入手术不可预知情况并由家长签字同意后,遂对2例患儿进行经喉罩支气管镜下钬激光联合氩气刀和二氧化碳( CO2)冷冻治疗,分析患儿的临床资料、并发症及术后转归、随访情况。结果2例手术过程顺利,例1术后紧贴声门下的肉芽组织被完全清除,2例患儿声门下环形狭窄完全解除,治疗前呼吸道狭窄处周长约2.5 mm,治疗后,周长达5.2 mm,4.0 mm支气管镜进出无障碍,术后气管导管均成功拔除,呼吸困难均明显改善。2例患儿治疗后即刻、7 d、30 d和90 d镜下检查结果示狭窄处开放良好。术中有血氧饱和度下降及心率增快或减慢,暂停操作及恢复给氧后立即恢复,术中及术后未见异常血流动力学改变,2例目前仍在随访中。结论经喉罩钬激光、氩气刀及CO2冷冻治疗可用于后天性肉芽组织增生引起的声门下狭窄,方法安全、有效,近期效果显著,远期仍在进一步随访评估。%Objective To explore the operating methods,the effectiveness and safety for 2 cases of tracheal in-tubation related severe subglottic stenosis under laryngeal mask by using bronchoscopy in the diagnosis and interven-tional treatment. Methods Two male patients ( age at 4 and 11 months) both had difficulty breathing and weaning failure after endotracheal intubation,who were diagnosed with severe subglottic stenosis through CT and bronchoscopy examination. All parents signed their consent after being fully informed of treatment risks. Two cases were treated under bronchoscopic holmium laser combined with argon plasma coagulation and

  1. Effects of Nitrogen contamination in liquid Argon

    Science.gov (United States)

    Acciarri, R.; Antonello, M.; Baibussinov, B.; Baldo-Ceolin, M.; Benetti, P.; Calaprice, F.; Calligarich, E.; Cambiaghi, M.; Canci, N.; Carbonara, F.; Cavanna, F.; Centro, S.; Cocco, A. G.; Di Pompeo, F.; Fiorillo, G.; Galbiati, C.; Gallo, V.; Grandi, L.; Meng, G.; Modena, I.; Montanari, C.; Palamara, O.; Pandola, L.; Piano Mortari, G. B.; Pietropaolo, F.; Raselli, G. L.; Roncadelli, M.; Rossella, M.; Rubbia, C.; Segreto, E.; Szelc, A. M.; Ventura, S.; Vignoli, C.

    2010-06-01

    A dedicated test of the effects of Nitrogen contamination in liquid Argon has been performed at the INFN-Gran Sasso Laboratory (LNGS, Italy) within the WArP R&D program. A detector has been designed and assembled for this specific task and connected to a system for the injection of controlled amounts of gaseous Nitrogen into the liquid Argon. The purpose of the test is to detect the reduction of the Ar scintillation light emission as a function of the amount of the Nitrogen contaminant injected in the Argon volume. A wide concentration range, spanning from ~ 10-1 ppm up to ~ 103 ppm, has been explored. Measurements have been done with electrons in the energy range of minimum ionizing particles (γ-conversion from radioactive sources). Source spectra at different Nitrogen contaminations are analyzed, showing sensitive reduction of the scintillation yield at increasing concentrations. Direct PMT signal acquisition exploiting high time resolution by fast waveform recording allowed high precision extraction of the main characteristics of the scintillation light emission in contaminated LAr. In particular, the decreasing behavior in lifetime and relative amplitude of the slow component is found to be appreciable starting from Script O(1 ppm) of Nitrogen concentrations. The rate constant of the quenching process induced by Nitrogen in liquid Ar has been found to be kQ(N2) = 0.11 ± 0.01 μs-1ppm-1, consistent with a previous measurement of this quantity but with significant improvement in precision. On the other hand, no evidence for absorption by N2 impurities has been found up to the higher concentrations here explored.

  2. Argon diffusion from biotite at high temperature and pressure

    Institute of Scientific and Technical Information of China (English)

    陈道公; 贾命命; 李彬贤; 陆全明; 谢鸿森; 侯渭

    1995-01-01

    t The experiments of argon diffusion dynamics for biotite were carried out at 700 -1000℃ and 0.5 - 2,0 GPa and the diffusion coefficient and activation energy using different models have been calculated. The results indicate that the pressure does affect the argon diffusion and its effect is opposite to that of temperature. When p increases, the activation energy increases and diffusion coefficient decreases. The relation between pressure, closure temperature and cooling rate has been obtained. It is postulated that in low T and high p conditions, the argon diffusion from the environment to the system could occur and incur the appearance of the external argon in minerals.

  3. Near-infrared scintillation of liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, T. [Fermilab; Escobar, C. O. [Campinas State U.; Lippincott, W. H. [Fermilab; Rubinov, P. [Fermilab

    2016-03-03

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  4. Near-infrared scintillation of liquid argon

    CERN Document Server

    Alexander, T; Lippincott, W H; Rubinov, P

    2016-01-01

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  5. Argon isotope fractionation induced by stepwise heating

    Science.gov (United States)

    Trieloff, Mario; Falter, Martina; Buikin, Alexei I.; Korochantseva, Ekaterina V.; Jessberger, Elmar K.; Altherr, Rainer

    2005-03-01

    Noble gas isotopes are widely used to elucidate the history of the rocks in which they have been trapped, either from distinct reservoirs or by accumulation following radioactive decay. To extract noble gases from their host rocks, stepwise heating is the most commonly used technique to deconvolve isotopically different components, e.g., atmospheric, in situ radiogenic, or excess radiogenic from mantle or crustal reservoirs. The accurate determination of the isotopic composition of these different components is of crucial importance, e.g., for ages obtained by 40Ar- 39Ar stepheating plateaus. However, diffusion theory-based model calculations predict that the stepwise thermal extraction process from mineral phases induces isotope fractionation and, hence, adulterates the original composition. Such effects are largely unconsidered, as they are small and a compelling experimental observation is lacking. We report the first unequivocal evidence for significant mass fractionation of argon isotopes during thermal extraction, observed on shungite, a carbon-rich Precambrian sedimentary rock. The degree of fractionation, as monitored by 38Ar/ 36Ar and 40Ar/ 36Ar ratios, very well agrees with theoretical predictions assuming an inverse square root dependence of diffusion coefficient and atomic mass, resulting in easier extraction of lighter isotopes. Hence, subatmospheric 40Ar/ 36Ar ratios obtained for argon extracted at low temperatures may not represent paleoatmospheric argon. Shungite argon resembles modern atmospheric composition, but constraints on the timing of trapping appear difficult to obtain, as shungites are multicomponent systems. In 40Ar- 39Ar stepwise heating, the isotope fractionation effect could cause systematic underestimations of plateau ages, between 0.15 and 0.4% depending on age, or considerably higher if samples contain appreciable atmospheric Ar. The magnitude of this effect is similar to the presently achieved uncertainties of this increasingly

  6. Argon Purification Studies and a Novel Liquid Argon Re-circulation System

    CERN Document Server

    Mavrokoridis, K; Coleman, J; Lightfoot, P K; McCauley, N; McCormick, K J; Touramanis, C

    2011-01-01

    Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficacy of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O_2, H_2O, N_2 and CO_2 in the range of between 0.01 ppm to 1000 ppm - H_2O was found to have the most profound effect on gaseous argon scintillation light, and N_2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O_2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N_2 gas and H_2O vapou...

  7. Ion-beam excitation of liquid argon

    CERN Document Server

    Hofmann, M; Heindl, T; Neumeier, A; Oberauer, L; Potzel, W; Roth, S; Schönert, S; Wieser, J; Ulrich, A

    2015-01-01

    The scintillation light of liquid argon has been recorded wavelength and time resolved with very good statistics in a wavelength interval ranging from 118 nm through 970 nm. Three different ion beams, protons, sulfur ions and gold ions, were used to excite liquid argon. Only minor differences were observed in the wavelength-spectra obtained with the different incident particles. Light emission in the wavelength range of the third excimer continuum was found to be strongly suppressed in the liquid phase. In time-resolved measurements, the time structure of the scintillation light can be directly attributed to wavelength in our studies, as no wavelength shifter has been used. These measurements confirm that the singlet-to-triplet intensity ratio in the second excimer continuum range is a useful parameter for particle discrimination, which can also be employed in wavelength-integrated measurements as long as the sensitivity of the detector system does not rise steeply for wavelengths longer than 190 nm. Using ou...

  8. Electron scattering and transport in liquid argon

    International Nuclear Information System (INIS)

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies

  9. Pollution of liquid argon after neutron irradiation

    CERN Document Server

    Andrieux, M L; Collot, J; de Saintignon, P; Ferrari, A; Hostachy, J Y; Hoummada, A; Martin, P; Merkel, B; Puzo, P; Sauvage, D; Wielers, M

    2001-01-01

    The purpose of the neutron facility installed at SARA is to investigate the behavior of various materials to be used in the ATLAS liquid argon calorimeter, when submitted to fast neutron radiation. The samples are placed in a liquid argon cryostat a few cm away from the neutron source. Various pieces of the electromagnetic calorimeter have been tested in order to evaluate the rate of pollution of the liquid and consequently the possible signal loss in energy measurements. The average fluence was equivalent to the maximum expected in the calorimeter in about 10 years. The most striking feature of the results is that the pollution is not due to oxygen, at least for most of it. Using a particular value of the absorption length derived from these data, a simulation was carried out and the energy signal loss in the calorimeter could be predicted. Within the limits of our present knowledge, the conclusion is that damages due to this pollution will not be a problem. (17 refs).

  10. Pollution of liquid argon after neutron irradiation

    International Nuclear Information System (INIS)

    The purpose of the neutron facility installed at SARA is to investigate the behavior of various materials to be used in the ATLAS liquid argon calorimeter, when submitted to fast neutron radiation. The samples are placed in a liquid argon cryostat a few cm away from the neutron source. Various pieces of the electromagnetic calorimeter have been tested in order to evaluate the rate of pollution of the liquid and consequently the possible signal loss in energy measurements. The average fluence was equivalent to the maximum expected in the calorimeter in about 10 years. The most striking feature of the results is that the pollution is not due to oxygen, at least for most of it. Using a particular value of the absorption length derived from these data, a simulation was carried out and the energy signal loss in the calorimeter could be predicted. Within the limits of our present knowledge, the conclusion is that damages due to this pollution will not be a problem

  11. Low-energy structure in the ionization of argon:Comparison of experiment with theory

    Institute of Scientific and Technical Information of China (English)

    Feng Li-Qiang; Chu Tian-Shu; Wang Li

    2013-01-01

    The above-threshold ionization of argon in an intense 70-fs,400-nm linearly polarized laser pulse has been investigated by the velocity map imaging techniques,combined with an attosecond-resolution quantum wave packet dynamics method.There is a quantitative agreement in all dominant features between the experiment and the theory.Moreover,a peak-splitting phenomenon in the first energy peak has been observed at high pulse intensity.Further,through the theoretical analysis,an ac Stark splitting with evident resonant and nonresonant ionization pathways has been found to be the physical reason for the experimental observations.

  12. The Effect of the Argon Carrier Gas in the Multiphoton Dissociation-Ionization of Tetracene

    OpenAIRE

    Carmen Cisneros; Ignacio ÃÂlvarez; Alfonso Guerrero; Alejandro San Román; Juan Carlos Poveda

    2008-01-01

    The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG), has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z). The results show that the dynamic of photodissociation at ~1010 W⋅cm-2 intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the...

  13. Two-photon excitation/ionization of the 1s-shell of the argon atom

    CERN Document Server

    Novikov, S A

    2002-01-01

    The absolute values and the shape of the two-photon excitation/ionization cross section of the 1s-shell of the argon atom are calculated with inclusion of the many-particle effects, i.e., the relaxation of the atomic residue in the field of the vacancies created, and the decay of the vacancies into the channels of Auger and (or) radiative types. The wavefunctions of the one-particle states are calculated in non-relativistic approximation. The calculations are performed for both linear and circular polarization of the laser beam.

  14. Two-photon excitation/ionization of the 1s-shell of the argon atom

    International Nuclear Information System (INIS)

    The absolute values and the shape of the two-photon excitation/ionization cross section of the 1s-shell of the argon atom are calculated with inclusion of the many-particle effects, i.e., the relaxation of the atomic residue in the field of the vacancies created, and the decay of the vacancies into the channels of Auger and (or) radiative types. The wavefunctions of the one-particle states are calculated in non-relativistic approximation. The calculations are performed for both linear and circular polarization of the laser beam.

  15. Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber

    OpenAIRE

    Andreas Hoffmann; Michael Zürch; Christian Spielmann

    2015-01-01

    In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV) spectrum, where total yie...

  16. WARP: a double phase argon programme for dark matter detection

    International Nuclear Information System (INIS)

    WARP (Wimp ARgon Programme) is a double phase Argon detector for Dark Matter search under construction at Laboratori Nazionali del Gran Sasso. We present recent results obtained operating a prototype with a sensitive mass of 2.3 litres deep underground

  17. Stopping Power of Solid Argon for Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Grauersen, O.;

    1981-01-01

    By means of the Rutherford-backscattering method, the stopping cross section of solid argon has been measured for 0.5–3 MeV helium ions to an accuracy of not, vert, similar3%. The results agree within the experimental accuracies with our earlier measurements for gaseous argon over the energy region...

  18. Nitrogen Removal from Molten Steel under Argon DC Glow Plasma

    Institute of Scientific and Technical Information of China (English)

    SUN Ming-shan; DING Wei-zhong; LU Xiong-gang

    2005-01-01

    Under argon DC glow plasma, the nitrogen removal from molten steel was studied. The experimental result showed that nitrogen mass percent could be reduced to 0.000 8%. The change of polarity had no impact on nitrogen removal when the nitrogen mass percent was low. The mechanism of denitrogenation of molten steel under argon DC glow plasma was discussed.

  19. Bilateral Simultaneous Rhegmatogenous Retinal Detachment following Laser in situ Keratomileusis

    Directory of Open Access Journals (Sweden)

    Erhan Yumusak

    2016-06-01

    Full Text Available A 21-year-old woman developed simultaneous rhegmatogenous retinal detachment after laser in situ keratomileusis (LASIK in both eyes. She underwent pars plana vitrectomy surgery combined with endolaser photocoagulation and silicone oil tamponade in the right eye. A week later, pneumatic retinopexy was done in the left eye. As the retinal tear did not seal, 360° scleral buckling surgery was performed and retina was attached. Bilateral simultaneous rhegmatogenous retinal detachment after LASIK for correction of myopia can be a serious complication. Patients should be informed about the possibility of this complication.

  20. 联合方法治疗新生血管性青光眼疗效观察%Compound T rabeculectomy and Retinal Photocoagulation and Vitreous Injection Ranibizumab in the M anagement of New Vascular Glaucoma

    Institute of Scientific and Technical Information of China (English)

    林芳; 齐美华; 赵静

    2015-01-01

    Objective To comparatively evaluate the efficacy and safety profiles of compound trabeculecto-my and Retinal photocoagulation and Vitreous injection Ranibizumab in the management of New vascular glauco-ma .Method Clinical records of 8 patients (8 eyes) with New vascular glaucoma secondary to RVO whose fun-dus oculi can be watched to be treated with Retinal laser photocoagulation first the pathants were threated with Retinal laser photocoagulation ,the second were Vitreous injection Ranibizumab seven days with compound tra-beculectomy after surgery ,according to patients iop and Anterior chamber to teach patients to learning Eye mas-sage?Record visions ,central macular thickness(CM T ) ,intraocular pressure(IOP) ,the degrade of Retinal neo-vascularization of fundus oculi and new vessels changes of iris and angles in Preoperative and postoperative 3 months ,6 months ,1 2 months .Result The Vision:3 months:(0 .0 4 ± 0 .0 4 ) ,6 months:(0 .0 6 ± 0 .0 5 ) ,1 2 months:(0 .0 5 ± 0 .0 4 ) ,4 eye’s Vision were improved 3 eye’s Vision werenot improved .The one eye is No light perception .IOP:3 months:(1 3 .2 4 ± 2 .2 3 )mmhg ,6 months:(1 5 .4 ± 2 3 .4 2 )mmhg ,1 2 months:(1 8 .2 5 ± 3 .1 5 ) mmhg ,6 patients can controled IOP under 2 1 mmhg ,postoperative one patient iop can be controled in normal in first 3 months ,give Alphagan eye water in rising to 2 1 mmhg of iop ,iop can be control in 1 8 mmhg ,6 months lat-er the iop rise to 1 9 mmhg ,in 9 months the iop rised to 2 1 mmhg ,Brinzolamide eye water was used ,iop can be control in 2 0 mmhg ,in 1 2 months ,iop is 2 2 mmhg ,2 2 mmhg ,in Process ,the patient Supplement Retinal photo-coagulation twice new vessels changes of iris and angles:5 cases degrade ,3 cases Reduce ,FFA :Capillary zone de-grade of 5 cases;Capillary zone degrade of 3 cases in Supplement Retinal laser photocoagulation ,CM T :Before treatment and1 week ,2 weeks ,4 weeks ,8 weeks ,1 2 weeks after Vitreous cavity injection was:(4 4 0 .3 6 ± 5 0

  1. Análise química e morfológica do esmalte dentário humano tratado com laser argônio durante a colagem ortodôntica Chemical and morphological analysis of the human dental enamel treated with argon laser during orthodontic bonding

    OpenAIRE

    Glaucio Serra Guimarães; Liliane Siqueira de Morais; Carlos Nelson Elias; Carlos André de Castro Pérez; Ana Maria Bolognese

    2011-01-01

    INTRODUÇÃO: as principais utilizações do laser argônio na Ortodontia são a redução do tempo de polimerização durante a colagem ortodôntica e o aumento da resistência à cárie do esmalte dentário. OBJETIVO: o objetivo deste trabalho foi avaliar as alterações químicas e morfológicas do esmalte dentário humano tratado com laser argônio nos parâmetros da colagem ortodôntica. MÉTODOS: quinze primeiros pré-molares hígidos, extraídos por indicação ortodôntica, foram selecionados e seccionados no sent...

  2. Impact of changes in metabolic control on progression to photocoagulation for clinically significant macular oedema:a 20 year study of type 1 diabetes

    DEFF Research Database (Denmark)

    Sander, B.; Larsen, M.; Andersen, Elisabeth Wreford;

    2013-01-01

    Center from 1988 to 2008, using the endpoint referral to first photocoagulation treatment for clinically significant diabetic macular oedema. The analysis included 1,878 patients (median observation, 8 years). Changes were defined as the inter-visit change; in the case of an event the last event...... model. A recent decrease of ≥0.5 percentage points or an increase in HbA1c of >0.5 percentage points per 6 months was associated with HRs of 3.04 and 1.28, respectively, compared with lesser changes in HbA1c. Conclusions/interpretation In this study, large recent...

  3. Merging of high speed argon plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Case, A.; Messer, S.; Brockington, S.; Wu, L.; Witherspoon, F. D. [HyperV Technologies Corp., Chantilly, Virginia 22180 (United States); Elton, R. [University of Maryland, College Park, Maryland 20742 (United States)

    2013-01-15

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

  4. Commissioning of the ATLAS liquid argon calorimeters

    CERN Document Server

    Rezaie, Erfan

    ATLAS, a multi-purpose detector built at the LHC at CERN, requires an extensive commissioning campaign to be ready for proton-proton collisions. In this work, we focus on the commissioning of the liquid Argon (LAr) calorimeters, with emphasis on commissioning with cosmic rays. First we outline one phase of the commissioning work, which involves testing of the front-end electronics of the two endcap calorimeters. We then describe two cosmic ray generators as input to a Monte-Carlo simulation of cosmic rays in ATLAS, and compare their results. Finally, we explain a technique developed for this work which uses information from the Tile calorimeters to predict the timing of cosmic rays within the LAr calorimeters, because cosmic rays occur randomly in time whereas the electronics are clocked at [Special characters omitted.] . The results from this analysis tool are compared to default tools, using both simulated and real cosmic ray data in the calorimeters.

  5. Fiber Optic Laser Delivery For Endarterectomy Of Experimental Atheromas

    Science.gov (United States)

    Eugene, John; Pollock, Marc E.; McColgan, Stephen J.; Hammer-Wilson, Marie; Berns, Michael W.

    1986-08-01

    Fiber optic delivery of argon ion laser energy and Nd-YAG laser energy were compared by the performance of open laser endarterectomy in the rabbit arteriosclerosis model. In Group I, 6 open laser endarterectomies were performed with an argon ion laser (488 nm and 514.5 nm) with the laser beam directed through a 400 pm quartz fiber optic. In Group II, 6 open laser endarterectomies were performed with a Nd-YAG laser (1.06 pm) with the laser beam directed through a 600 pm quartz fiber optic. Gross and light microscopic examination revealed smooth endarterectomy surfaces with tapered end points in Group I. In Group II, the endarterectomy surfaces were uneven and perforation occurred at 5/6 end points. Although energy could be precisely delivered with each laser by fiber optics, satisfactory results could only be achieved with the argon ion laser because argon ion energy was well absorbed by atheromas. Successful intravascular laser use requires a strong interaction between wavelength and atheroma as well as a precise delivery system.

  6. Cutaneous laser therapy.

    Science.gov (United States)

    Dixon, J A; Gilbertson, J J

    1985-12-01

    The carbon dioxide laser is useful for vaporizing lesions and applying incisions, the argon laser coagulates superficial vascular lesions and the neodymium-YAG laser is used for large vascular and more deeply situated lesions. Many patients with port-wine stains have been treated with excellent to poor results, major problems consisting of incomplete color removal and hypertrophic scarring (occurring in 4% to 23% of cases). While results are imperfect, patients are satisfied with the improvement in 86% of cases. Lasers have been used with good results for treating patients with strawberry angioma of infancy, pyogenic granuloma, telangiectasia of the face, decorative tattoos, genital condylomata and warts. The results of laser treatment of essential telangiectasia of the lower extremities have generally been poor. The CO(2) laser has been effective in excising small lesions and elevating skin flaps. PMID:4090490

  7. Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber

    CERN Document Server

    Badhrees, I; Kreslo, I; Messina, M; Moser, U; Rossi, B; Weber, M S; Zeller, M; Altucci, C; Amoruso, S; Bruzzese, R; Velotta, R

    2010-01-01

    This paper reports on laser-induced multiphoton ionization at 266 nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: $\\sigma_ex$=(1.24$\\pm$0.10stat $\\pm$0.30syst)$\\times$10^{-56} cm$^4$s{-1}.

  8. Infrared spectra and electronic structure calculations for NN complexes with U, UN, and NUN in solid argon, neon, and nitrogen.

    Science.gov (United States)

    Andrews, Lester; Wang, Xuefeng; Gong, Yu; Kushto, Gary P; Vlaisavljevich, Bess; Gagliardi, Laura

    2014-07-17

    Reactions of laser-ablated U atoms with N2 molecules upon codeposition in excess argon or neon at 4 K gave intense NUN and weak UN absorptions. Annealing produced progressions of new absorptions for the UN2(N2)1,2,3,4,5 and UN(N2)1,2,3,4,5,6 complexes. The neon-to-argon matrix shift decreases with increasing NN ligation and therefore the number of noble gas atoms left in the primary coordination sphere around the NUN molecule. Small matrix shifts are observed when the secondary coordination layers around the primary UN2(N2)1,2,3,4,5 and UN(N2)1,2,3,4,5,6 complexes are changed from neon-to-argon to nitrogen. Electronic structure, energy, and frequency calculations provide support for the identification of these complexes and the characterization of the N≡U≡N and U≡N core molecules as terminal uranium nitrides. Codeposition of U with pure nitrogen produced the saturated U(NN)7 complex, which UV irradiation converted to the NUN(NN)5 complex with slightly lower frequencies than found in solid argon.

  9. Current and Future of Laser Therapy in the Management of Glaucoma

    OpenAIRE

    Ekici, Feyzahan; Waisbourd, Michael; Katz, L. Jay

    2016-01-01

    There has been tremendous progress in the past decades in the utilization of lasers for treating patients with glaucoma. This article reviews the use of lasers in different areas of glaucoma, including the shift from argon laser trabeculoplasty (ALT) to selective laser trabeculoplasty (SLT), laser trabeculoplasty as an initial treatment for glaucoma, new laser trabeculoplasty procedures under investigation, and other recent laser treatment modalities such as endoscopic cyclophotocoagulation a...

  10. LArGe - A liquid argon scintillation veto for GERDA

    OpenAIRE

    Heisel, M.(Max-Planck-Institut für Kernphysik, Heidelberg, Germany)

    2011-01-01

    LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the Gerda experiment. Gerda searches for the neutrinoless double-beta decay in 76Ge, by operating naked germanium detectors submersed into 65 m3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used...

  11. Practical reactor production of {sup 41}Ar from argon clathrate

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, J.R. E-mail: jmercer@pharmacy.ualberta.ca; Duke, M.J.M.; McQuarrie, S.A

    2000-06-01

    The radionuclide {sup 41}Ar has many ideal properties as a gas flow tracer. However, the modest cross-section of {sup 40}Ar for thermal neutron activation makes preparation of suitable activities of {sup 41}Ar technically difficult particularly for low flux reactors. Argon can however be trapped in a molecular complex called a clathrate that can then be irradiated. We prepared argon clathrate and explored its irradiation and stability characteristics. Argon clathrate can be used to provide gigabecquerel quantities of {sup 41}Ar even with low power reactors.

  12. The Effects of Dissolved Methane upon Liquid Argon Scintillation Light

    CERN Document Server

    Jones, B J P; Back, H O; Collin, G; Conrad, J M; Greene, A; Katori, T; Pordes, S; Toups, M

    2013-01-01

    In this paper we report on measurements of the effects of dissolved methane upon argon scintillation light. We monitor the light yield from an alpha source held 20 cm from a cryogenic photomultiplier tube (PMT) assembly as methane is injected into a high-purity liquid argon volume. We observe significant suppression of the scintillation light yield by dissolved methane at the 10 part per billion (ppb) level. By examining the late scintillation light time constant, we determine that this loss is caused by an absorption process and also see some evidence of methane-induced scintillation quenching at higher concentrations (50-100 ppb). Using a second PMT assembly we look for visible re-emission features from the dissolved methane which have been reported in gas-phase argon methane mixtures, and we find no evidence of visible re-emission from liquid-phase argon methane mixtures at concentrations between 10 ppb and 0.1%.

  13. Evidence of electric breakdown induced by bubbles in liquid argon

    CERN Document Server

    Bay, F; Murphy, S; Resnati, F; Rubbia, A; Sergiampietri, F; Wu, S

    2014-01-01

    We report on the results of a high voltage test in liquid argon in order to measure its dielectric rigidity. Under stable conditions and below the boiling point, liquid argon was found to sustain a uniform electric field of 100 kV/cm, applied in a region of 20 cm$^2$ area across 1 cm thick gap. When the liquid is boiling, breakdowns may occur at electric fields as low as 40 kV/cm. This test is one of the R&D efforts towards the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER) as proposed Liquid Argon Time Projection Chamber (LAr TPC) for the LBNO observatory for neutrino physics, astrophysics and nucleon decay searches.

  14. A purity monitoring system for liquid argon calorimeters

    International Nuclear Information System (INIS)

    For liquid argon calorimeters electronegative impurities dissolved in the medium degrade the detector response and deteriorate the energy resolution, especially at high energies. A concept for a purity monitoring system for liquid argon calorimeters has been developed and is presented here. Special combined monitors of 241Am- and 207Bi-cells are used to monitor the concentration of impurities. The working principle as well as results from test measurements are discussed

  15. Size Determination of Argon Clusters from a Rayleigh Scattering Experiment

    Institute of Scientific and Technical Information of China (English)

    LEI An-Le; ZHAI Hua-Jin; LIU Bing-Chen; LI Zhong; NI Guo-Yuan; XU Zhi-Zhan

    2000-01-01

    Argon clusters are produced in the process of adiabatic expansion of a high backing pressure gas into vacuum through a nozzle. The cluster size is determined by a Rayleigh scattering measurement. The scattered signal measured is proportional to the 2.78th power of gas stagnation pressure. The average cluster sizes vary from 100 to more than 12000 atoms/cluster with the argon gas backing pressures ranging between 3 to 45 atm.

  16. Pulse shape discrimination studies in a liquid Argon scintillation detector

    OpenAIRE

    Pollmann, T.

    2007-01-01

    Liquid rare gases have been gaining popularity as detector media in rare event searches, especially dark matter experiments, and one factor driving their adoption is the possibility to recognise different types of ionizing radiation by the pulse shapes they evoke. This work on pulse shape discrimination in a liquid argon scintillation detector was done in the framework of the GERDA experiment, where liquid argon scintillation signals may be used for background suppression purposes. Liquid arg...

  17. Electronic relaxation dynamics of a metal atom deposited on argon cluster

    International Nuclear Information System (INIS)

    This thesis is a study on the interaction between electronically excited atomic states and a non-reactive environment. We have theoretically and experimentally studied situations where a metal atom (Ba or K) is placed in a finite size environment (argon cluster). The presence of the medium affects the electronic levels of the atom. On the other side, the excitation of the atom induces a relaxation dynamics of the electronic energy through the deformation of the cluster. The experimental part of this work focuses on two aspects: the spectroscopy and the dynamics. In both cases a first laser electronically excites the metal atom and the second ionizes the excited system. The observable is the photoelectron spectrum recorded after photoionization and possibly information on the photoion which are also produced. This pump/probe technique, with also two lasers, provide the ultrafast dynamic when the lasers pulses used are of ultrashort (60 fs). The use of nanosecond lasers leads to resonance spectroscopic measurement, unresolved temporally, which give information on the position of the energy levels of the studied system. From a theoretical point-of-view, the excited states of M-Arn were calculated at the ab initio level, using large core pseudo-potential to limit the active electrons of the metal to valence electrons. The study of alkali metals (potassium) is especially well adapted to this method since only one electron is active. The ab-initio calculation and a Monte-Carlo simulation where coupled to optimize the geometry of the KArn (n = 1-10) cluster when K is in the ground state of the neutral and the ion, or excited in the 4p or 5s state. Calculations were also conducted in collaboration with B. Gervais (CIMAP, Caen) on KArn clusters having several tens of argon atoms. Absorption spectra were also calculated. From an experimental point-of-view, we were able to characterize the excited states of potassium and barium perturbed by the clusters. In both cases a

  18. Power Consideration for Pulsed Discharges in Potassium Seeded Argon

    Institute of Scientific and Technical Information of China (English)

    XIA Sheng-Guo; HE Jun-Jia; LIU Ke-Fu

    2007-01-01

    Minimization of energy consumed in plasma generation is critical for applications, in which a large volume of plasmas is needed. We suggest that a high electron density atmospheric pressure plasmas can be generated by pulsed discharges in potassium seeded argon at an elevated temperature with a very small power input. The ionization efficiency and power budget of pulsed discharges in such plasmas are analytically studied. The results show that ionization efficiency of argon, especially at small reduced electric field E/N (the ratio of the electric field to the gas number density), is improved effectively in the presence of small amount of potassium additives. Power input of pulsed discharge to sustain a prescribed average level of ionization in potassium seeded argon is three orders of magnitude lower than that in pure argon. Further, unlike in pure argon, it is found that very short high-voltage pulses with very high repetition rates are unnecessary in potassium seeded argon. A pulse with 100ns of pulse duration, 5kHz of repetition rate, and 2Td (1 Td = 1 ×10-21 Vm2) of E/N is enough to sustain an electron density of 10l9m-3 in 1 atm 1500 K Ar+0.1% K mixture, with a very small power input of about 0.08 × 104 W/m3.

  19. Energy resolution for α-particles in doped liquid argon

    International Nuclear Information System (INIS)

    The report describes experiments on the effect of allene doped in liquid argon. In the case of doped argon, a large amount of charge is obtained even at low electric fields and the measured charge increases with the field gradually. This can be explained as follows; part of deposited energy which does not form charge in pure argon contributes to charge signal in doped argon through scintillation photons which ionize allene molecules. The main factors determining the energy resolution for α-particles are considered to be (1) fluctuation in the number of produced ion-electron pairs as expressed by the Fano factor, (2) fluctuation in recombination process, (3) fluctuation in photoionization, (4) fluctuation due to the condition of radioactive source and surface of electrodes, (5) fluctuation in geometrical efficiency due to the range and emission angle of α-particles in liquid argon, and (6) electronic noise of amplifier. The factors (1) and (3) can be neglected because of a large number of associated electrons or photons. In pure liquid argon, the factor (2) may be a cause of bad resolution since the fraction of the produced ion-electron paris which do not recombine is small and the photoionization process never occurs for photons emitted through recombination. (N.K.)

  20. Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber

    Directory of Open Access Journals (Sweden)

    Andreas Hoffmann

    2015-11-01

    Full Text Available In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6 for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV spectrum, where total yield and spectral selectivity in the XUV are the targets of the optimization approach. The effect of using sulfur hexafluoride for pulse-shaping the XUV yield can be doubled compared to pulse compression and pulse-shaping using argon and the spectral range for selective optimization of a single harmonic can be extended. The obtained results are of interest for extending the range of ultrafast science applications drawing on tailored XUV fields.

  1. Growth of n-type ZnO thin films by using mixture gas of hydrogen and argon

    Institute of Scientific and Technical Information of China (English)

    Zhou Xin; Wang Shi-Qi; Lian Gui-Jun; Xiong Guang-Cheng

    2006-01-01

    High-quality oxide semiconductor ZnO thin films were prepared on single-crystal sapphire and LaAlO3 substrates by pulsed laser deposition (PLD) in the mixture gas of hydrogen and argon. Low resistivity n-type ZnO thin films with smoother surface were achieved by deposition at 600℃ in 1Pa of the mixture gas. In addition, ferromagnetism was observed in Co-doped ZnO thin films and rectification Ⅰ-Ⅴ curves were found in p-GaN/n-ZnO and p-CdTe/n-ZnO heterostructure junctions. The results indicated that using mixture gas of hydrogen and argon in PLD technique was a flexible method for depositing high-quality n-type oxide semiconductor films, especially for the multilayer thin film devices.

  2. Plasma and laser kinetics and field emission from carbon nanotube fibers for an Advanced Noble Gas Laser (ANGL)

    Science.gov (United States)

    Moran, Paul J.; Lockwood, Nathaniel P.; Lange, Matthew A.; Hostutler, David A.; Guild, Eric M.; Guy, Matthew R.; McCord, John E.; Pitz, Greg A.

    2016-03-01

    A metastable argon laser operating at 912 nm has been demonstrated by optically pumping with a pulsed titanium sapphire laser to investigate the temporal dynamics of an Advanced Noble Gas Laser (ANGL). Metastable argon concentrations on the order of 1011 cm-3 were maintained with the use of a radio frequency (RF) capacitively coupled discharge. The end-pumped laser produced output powers under 2 mW of average power with pulse lengths on the order of 100 ns. A comparison between empirical results and a four level laser model using longitudinally average pump and inter-cavity intensities is made. An alternative, highly-efficient method of argon metastable production for ANGL was explored using carbon nanotube (CNT) fibers.

  3. New argon-argon (40Ar/39Ar) radiometric age dates from selected subsurface basalt flows at the Idaho National Laboratory, Idaho

    Science.gov (United States)

    Hodges, Mary K.; Turrin, Brent D.; Champion, Duane E.; Swisher, Carl C.

    2015-01-01

    In 2011, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected samples for 12 new argon-argon radiometric ages from eastern Snake River Plain olivine tholeiite basalt flows in the subsurface at the Idaho National Laboratory. The core samples were collected from flows that had previously published paleomagnetic data. Samples were sent to Rutgers University for argon-argon radiometric dating analyses.

  4. DOE Center of Excellence in Medical Laser Applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. (Oregon Medical Laser Center, Portland, OR (United States))

    1998-01-01

    An engineering network of collaborating medical laser laboratories are developing laser and optical technologies for medical diagnosis and therapy and are translating the engineering into medical centers in Portland, OR, Houston, TX, and Galveston, TX. The Center includes the University of Texas M.D. Anderson Cancer Center, the University of Texas-Austin, Texas A and M University, Rice University, the University Texas Medical Branch-Galveston, Oregon Medical Laser Center (Providence St. Vincent Medical Center, Oregon Health Sciences University, and Oregon Graduate Institute, Portland, OR), and the University of Oregon. Diagnostics include reflectance, fluorescence, Raman IR, laser photoacoustics, optical coherence tomography, and several new video techniques for spectroscopy and imaging. Therapies include photocoagulation therapy, laser welding, pulsed laser ablation, and light-activated chemotherapy of cancer (photodynamic therapy, or PDT). Medical applications reaching the clinic include optical monitoring of hyperbilirubinemia in newborns, fluorescence detection of cervical dysplasia, laser thrombolysis of blood clots in heart attack and brain stroke, photothermal coagulation of benign prostate hyperplasia, and PDT for both veterinary and human cancer. New technologies include laser optoacoustic imaging of breast tumors and hemorrhage in head trauma and brain stroke, quality control monitoring of dosimetry during PDT for esophageal and lung cancer, polarization video reflectometry of skin cancer, laser welding of artificial tissue replacements, and feedback control of laser welding.

  5. Proliferative Diabetic Retinopathy Surgery against the Background of Prior Retinal Laser Coagulation

    Directory of Open Access Journals (Sweden)

    Fazilat Bakhritdinova, PhD, ScD¹

    2013-03-01

    Full Text Available The study has been performed to compare the immediate and long-term outcomes of Vitreoretinal Surgery (VS on patients with Proliferative Diabetic Retinopathy (PDR in relation to Prior Retinal Laser Coagulation (PLC. The study included 56 patients (71 eyes with diabetes mellitus (type 2 - 52/93%, men – 39/75% complicated with proliferative diabetic retinopathy (PDR, requiring VS. Of these, 33 eyes (no PLC underwent primary vitrectomy, while the remaining 38 eyes (PLC had undergone panretinal laser coagulation over the past five years. In our study, PLC significantly contributed to the preservation of improved functional retinal status, despite the development of complications, which is an indication for VS. The PLC patients exhibited early recovery and a higher visual acuity throughout the observation period. Thus, the study revealed that in the case of prior VS, laser photocoagulation of the retina helps preserve the visual acuity, both at the time of and during the first year after surgery, reduces surgery duration and decreases the need to tamponade the vitreous cavity with silicone oil. Besides, PLC of the retina is accompanied by a significantly lower incidence of intra- and post-operational hemorrhage and reduces the need for repeated vitreoretinal procedures. The present study presents further arguments in favor of early retinal laser photocoagulation on patients with diabetes mellitus complicated by PDR.

  6. Evolution of Martian atmospheric argon: Implications for sources of volatiles

    Science.gov (United States)

    Hutchins, Kevin S.; Jakosky, Bruce M.

    We have examined processes affecting isotopes of argon (36Ar, 38Ar, 40Ar) in order to determine important atmospheric sources and sinks. Our simple model for argon evolution incorporates production of radiogenic argon in the mantle, outgassing of all argon species by extrusive and intrusive volcanism, and loss to space by knock-on sputtering above the exobase. Sputtering has been shown previously to be an important loss process for atmospheric species, especially isotopes of noble gases, which have few other mechanisms of escape. The integrated evolution of argon (36Ar, 38Ar, and 40Ar, respectively) is modeled in terms of these variables: (1) the planetary concentration of potassium, (2) the fraction of juvenile argon released catastrophically during the first 600 Myr., (3) potential variation in the time-history of sputtering loss from that suggested by Luhmann et al. [1992], and (4) the volume of total outgassing to the surface as compared to outgassing contributed by volcanic release. Our results indicate that Mars has lost between 85-95% of 36Ar and 70-88% of outgassed 40Ar. Due to this substantial loss, the planet must have outgassed the equivalent of between 10 and 100 times the total volume of gases released by extrusive and intrusive volcanics. This indicates that volcanic outgassing, alone, is insufficient to explain the present-day abundances of 36Ar and 40Ar in the Martian atmosphere. Similar calculations for 20Ne suggest outgassed volumes of between 100 and 1800 times in excess of that due to volcanism. This results in a distinct Ne/Ar elemental fractionation, with a preference for outgassing argon, of the order of 10 to 17. Although the results must be evaluated within the model uncertainties, the results are compelling in that they unequivocally show the existence of additional sources of atmospheric volatiles and helps define a means to identify them.

  7. Tracking of CFSE-labeled endothelial progenitor cells in laser-injured mouse retina

    Institute of Scientific and Technical Information of China (English)

    SHI Hui; YANG Wei; CUI Zhi-hua; LU Cheng-wei; LI Xiao-hong; LIANG Ling-ling; SONG E

    2011-01-01

    Background Endothelial progenitor cells (EPCs) transplantation is a promising therapeutic strategy for ischemic retinopathy. The current study aimed to establish a simple, reliable and fluorescent labeling method for tracking EPCs with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE) in laser-injured mouse retina.Methods EPCs were isolated from human umbilical cord blood mononuclear cells, cultivated, and labeled with various concentrations of CFSE. Based on fluorescence intensity and cell morphology, a 15 minutes incubation with 5 μmol/L CFSE at 37℃ was selected as the optimal labeling condition. The survival capability and the apoptosis rate of CFSE-labeled EPCs were measured by Trypan blue staining and Annexin V/PI staining assay respectively. Fluorescence microscopy was used to observe the label stability during the extended culture period. Labeled EPCs were transplanted into the vitreous cavity of pigmented mice injured by retinal laser photocoagulation. Evans Blue angiography and flat mounted retinas were examined to track the labeled cells.Results EPCs labeled with 5 μmol/L CFSE presented an intense green fluorescence and maintained normal morphology, with no significant changes in the survival capability or apoptosis rate after being labeled for 2 days, 1 and 4 weeks. The fluorescence intensity gradually decreased in the cells at the end of 4 weeks. Evans Blue angiography of the retina displayed the retinal capillarity network clearly and fluorescence leakage was observed around photocoagulated spots in the laser-injured mouse model. One week after transplantation of labeled EPCs, the fluorescent cells were identified around the photocoagulated lesions. Four weeks after transplantation, fluorescent tube-like structures were observed in the retinal vascular networks.Conclusion EPCs could be labeled by CFSE in vitro and monitored in vivo for at least 4 weeks, and participate in the repair of injured retinal vessels.

  8. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Science.gov (United States)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang

    2016-10-01

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN.

  9. Characterisation of GERDA Phase-I detectors in liquid argon

    International Nuclear Information System (INIS)

    GERDA will search for neutrinoless double beta decay in 76Ge by submerging bare enriched HPGe detectors in liquid argon. In GERDA Phase-I, reprocessed enriched-Ge detectors, which were previously operated by the Heidelberg-Moscow and IGEX collaborations, and reprocessed natural-Ge detectors from Genius-TF, will be redeployed. We have tested the operation and performance of bare HPGe detectors in liquid nitrogen and in liquid argon over more than three years with three non-enriched p-type prototype detectors. The detector handling and mounting procedures have been defined and the Phase-I detector technology, the low-mass assembly and the long-term stability in liquid argon have been tested successfully. The Phase-I detectors were reprocessed by Canberra Semiconductor NV, Olen, according to their standard technology but without the evaporation of a passivation layer. After their reprocessing, the detectors have been mounted in their low-mass holders and their characterisation in liquid argon performed. The leakage current, the counting characteristics and the efficiency of the detectors have been measured. The testing of the detectors was carried out in the liquid argon test stand of the GERDA underground Detector Laboratory (GDL) at LNGS. The detectors are now stored underground under vacuum until their operation in GERDA.

  10. The Spectroscopic Detectability of Argon in the Lunar Atmosphere

    CERN Document Server

    Parker, J W; Gladstone, G R; Shull, J M; Parker, Joel Wm.

    1999-01-01

    Direct measurements of the abundance of argon in the lunar atmosphere were made in 1973 by instruments placed on the Moon during the Apollo 17 mission, but the total daytime abundance is unknown due to instrument saturation effects; thus, until we are able to return to the Moon for improved direct measurements, we must use remote sensing to establish the daytime abundance. In this paper, we present a complete analysis of the potential for measuring argon in the lunar atmosphere via emission-line or absorption-line observations. We come to the surprising conclusion that the lower limit established by the in situ lunar argon measurements implies that any absorption-line measurement of argon in the lower, dayside lunar atmosphere requires analysis in the optically-thick regime. In light of this result, we present the results of our EUVS sounding rocket observations of the lunar occultation of Spica, which provide a new upper limit on the abundance of argon in the daytime lunar atmosphere. We also re-analyze a re...

  11. On the Role of Metastable Argon in Cold Atmospheric Pressure Plasma Jets with Shielding Gas Device

    Science.gov (United States)

    Schmidt-Bleker, Ansgar; Winter, Jorn; Sousa, Joao Santos; Puech, Vincent; Weltmann, Klaus-Dieter; Reuter, Stephan; ZIK plasmatis at the INP Greifswald e. V. Team; Laboratoire de Physique des Gaz et des Plasmas (LPGP), CNRS; Université Paris-Sud Team

    2014-10-01

    Shielding gas devices are a valuable tool for controlling the reactive species output of Cold Atmospheric Pressure Plasma (CAPP) Jets for biomedical applications. In this work we investigate the effect of different shielding gas compositions using a CAPP jet (kinpen) operated with argon. As shielding gas various mixtures of N2 and O2 are used. Metastable argon (Ar*) has been quantified using laser absorption spectroscopy and was identified as an important energy carrier in the CAPP jets effluent. The Ar* excitation dynamics was studied using phase resolve optical emission spectroscopy. Based on these findings a kinetic model for the gas phase chemistry has been developed that uses the Ar* density and dynamics as input and yields densities of O3, NO2, HNO2, HNO3, N2O5, H2O2 and N2O produced by the CAPP jet for different shielding gas compositions. The results are in good agreement with Fourier-Transform Infrared Spectroscopy measurements on these species. Authors gratefully acknowledge the funding by German Federal Ministry of Education a Research (BMBF) (Grant # 03Z2DN12).

  12. a Liquid Argon Time Projection Chamber for the Solar Neutrino Problem

    Science.gov (United States)

    Cheng, Mao-Tung

    The construction and successful test of a large liquid argon time projection chamber prototype detector is presented. This effort is a part of the ICARUS project which is aimed at the development of new detector techniques to uncover the very rare events like proton decay and solar neutrinos. The construction and test of this detector has been carried out at CERN from 1989 until the present time. The charge lifetime measured is 3.19 +/- 0.13 ms. We also report on a precision measurement of lifetime by a laser monitoring chamber and the operation of the recirculation system essential to keeping liquid for a long time. We show that a liquid argon detector is very well suited to study mass-enhanced neutrino oscillation (MSW effect) from the Sun by detecting simultaneous two modes of reaction. Ratio of two modes provides a model independent probe of neutrino oscillation, free of deviations from different solar models. Contour plots are presented at various threshold energies.

  13. Investigation of forbidden transitions in argon ions. [in laboratory plasma for solar corona simulation

    Science.gov (United States)

    Jalufka, N. W.

    1976-01-01

    An attempt has been made to observe the visible forbidden argon coronal lines at 553.6 nm (Ar X), 691.7 nm (Ar XI), 847.6 nm (Ar XIII), and 441.2 nm (Ar XIV) in a deuterium-argon plasma produced in a large theta pinch. The electron temperature (250 eV) and the electron density (5 by 10 to the 16th power per cu cm) were measured by Thomson scattering of ruby laser radiation. This temperature is adequate to produce ionization stages up to Ar XIV, as was verified by photographic observation of Ar XIV lines. No line corresponding to the coronal lines was observed from the high-temperature plasma, but lines with wavelengths very nearly identical to those of two of the forbidden transitions were observed; these lines were due to allowed transitions of Ar II in a cooler portion of the plasma. Calculation of rate coefficients in the Coulomb-Born approximation shows that for laboratory experiments, electron collisions are much more important than radiative decay in depopulating the upper state of the forbidden lines.

  14. 氩激光治疗糖尿病视网膜病变264例观察%Observation on Photocoagulation with Arqon for Treatment of 264 Cases of Diabetic Retinopathy

    Institute of Scientific and Technical Information of China (English)

    包欣; 林菁; 谢田华; 朱靖; 史惠琴; 袁松涛

    2012-01-01

    目的:观察氩激光光凝治疗不同分期糖尿病视网膜病变(diabetic retinopathy,DR)的疗效.方法:对264例513眼DR患者按病变不同分期分别行黄斑格栅样光凝、次全视网膜光凝(sPRP)和全视网膜光凝(PRP).随访3月-5年,观察患者视力、眼底及荧光血管造影情况.结果:总计有24.0%(123/513)的患眼视力得以上升,49.7 %(255/513)视力保持不变,26.3 %(135/513)视力下降.非增殖性DR激光治疗有效率为87.5%,增殖性DR有效率58.4 %(P<0.05).1型DM有效率43.5%,2型DM有效率81.4%(P<0.05).结论:氩激光能有效控制DR,减缓DR患者视力的丧失,非增殖性DR疗效明显优于增殖性DR,2型DM疗效优于1型DM.%Objective: To observe curative effect of photocoagulation with arqon on background diabetic retinopathy and proliferative diabetic retinopathy. Methods: We classified 513 eyes with 264 patients as background diabetic retinopathy and proliferative diabetic retinopathy with or not with cystoid macular edema. They were treated with grid patten photocoagulation, secondary panretinal photocoagulation (sPRP) and panretinal photocoagulation respectively. Followed up with visual acuity, ophthalmic fundus characteristics and fundus fluorescein angiography (FFA) for 3 months to 5 years. Results: Mean preoperative visual acuities and ophthalmic fundus characteristics were compared across groups. In all patients, visual acuity improved in 123 eyes (24 %); was unchanged in 255 eyes (49.7 %); and decreased in 135 eyes (26.3 %). The effective rate of photocoagulation on nonproliferative diabetic retinopathy is 87.5 % compared with 58.4 % on proliferative diabetic retinopathy(P<0.05), 43.5 % on type 1 diabetes mellitus compared with 81.4 % on type 2 diabetes mellitus. Conclutions: Photocoagulation with arqon can effectively restrain the decrease of visual acuity especially in proliferative diabetic retinopathy patients with type 2 diabetes mellitus.

  15. Lasers in endodontics: an overview

    Science.gov (United States)

    Frentzen, Matthias; Braun, Andreas; Koort, Hans J.

    2002-06-01

    The interest in endodontic use of dental laser systems is increasing. Developing laser technology and a better understanding of laser effects widened the spectrum of possible endodontic indications. Various laser systems including excimer-, argon+-, diode-, Nd:YAG-, Er:YAG- and CO2-lasers are used in pulp diagnosis, treatment of hypersensitivity, pulp capping, sterilization of root canals, root canal shaping and obturation or apicoectomy. With the development of new delivery systems - thin and flexible fibers - for many different wavelengths laser applications in endodontics may increase. Since laser devices are still relatively costly, access to them is limited. Most of the clinical applications are laser assisted procedures such as the removing of pulp remnants and debris or disinfection of infected root canals. The essential question is whether a laser can provide improved treatment over conventional care. To perform laser therapy in endodontics today different laser types with adopted wavelengths and pulse widths are needed, each specific to a particular application. Looking into the future we will need endodontic laser equipment providing optimal laser parameters for different treatment modalities. Nevertheless, the quantity of research reports from the last decade promises a genuine future for lasers in endodontics.

  16. Comparative evaluation between ranibizumab combined with laser and bevacizumab combined with laser versus laser alone for macular oedema secondary to branch retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    Shorya Vardhan Azad

    2014-01-01

    Full Text Available Purpose: To evaluate the anatomical and functional efficacy of combination therapy of intravitreal ranibizumab with laser or intravitreal bevacizumab with laser treatment compared to only laser treatment for macular edema due to branch retinal vein occlusion (BRVO. Materials and Methods: Thirty eyes of 30 patients with BRVO of at least 6 weeks duration were randomized into three groups: Group 1 received a single dose of intravitreal Ranibizumab followed by grid laser treatment, Group 2 received a single dose of intravitreal Bevacizumab followed by grid laser treatment, and Group 3 received grid laser alone. Outcomes at 6 months follow-up were reported. Data were collected on best corrected visual acuity (BCVA, central foveal thickness (CFT, and gain in lines of Snellen acuity. Results: At 6 month follow-up, the difference in the mean BCVA and CFT between the three treatment groups was not statistically significant (P > 0.05, all comparisons. Six eyes (60% in Group 1, four eyes (40% in Group 2 and two eyes (20% in Group 3 had a statistically significant gain of ≥3 lines of Snellen acuity (P < 0.05. Conclusion: Both ranibizumab and bevacizumab combined with laser photocoagulation, resulted in better outcomes than grid laser treatment.

  17. Metastable argon beam source using a surface wave sustained plasma

    International Nuclear Information System (INIS)

    A new source of metastable argon atoms in the thermal energy range is reported. The source is based on expanding a plasma sustained by electromagnetic surface waves in a quartz tube through a converging nozzle and extracting a beam from the supersonic free-expansion jet. The beam was characterized by time-of-flight measurements which yielded the absolute intensity and velocity distribution of the argon metastables. The source produced a maximum intensity of 6.2x1014 metastables per second per steradian, the highest time-averaged intensity of thermal argon metastables of any source reported to date. A simple picture of an expanding plasma in a recombination regime is used to explain the dependence of the metastable intensity on absorbed power

  18. On the electric breakdown in liquid argon at centimeter scale

    Science.gov (United States)

    Auger, M.; Blatter, A.; Ereditato, A.; Goeldi, D.; Janos, S.; Kreslo, I.; Luethi, M.; von Rohr, C. Rudolf; Strauss, T.; Weber, M. S.

    2016-03-01

    We present a study on the dependence of electric breakdown discharge properties on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  19. The Simulation of the ATLAS Liquid Argon Calorimetry

    CERN Document Server

    Archambault, J P; Carli, T; Costanzo, D; Dell'Acqua, A; Djama, F; Gallas, M; Fincke-Keeler, M; Khakzad, M; Kiryunin, A; Krieger, P; Leltchouk, M; Loch, P; Ma, H; Menke, S; Monnier, E; Nairz, A; Niess, V; Oakham, G; Oram, C; Pospelov, G; Rajagopalan, S; Rimoldi, A; Rousseau, D; Rutherfoord, J; Seligman, W; Soukharev, A; Strízenec, P; Tóth, J; Tsukerman, I; Tsulaia, V; Unal, G; Grahn, K J

    2008-01-01

    In ATLAS, all of the electromagnetic calorimetry and part of the hadronic calorimetry is performed by a calorimeter system using liquid argon as the active material, together with various types of absorbers. The liquid argon calorimeter consists of four subsystems: the electromagnetic barrel and endcap accordion calorimeters; the hadronic endcap calorimeters, and the forward calorimeters. A very accurate geometrical description of these calorimeters is used as input to the Geant 4-based ATLAS simulation, and a careful modelling of the signal development is applied in the generation of hits. Certain types of Monte Carlo truth information ("Calibration Hits") may, additionally, be recorded for calorimeter cells as well as for dead material. This note is a comprehensive reference describing the simulation of the four liquid argon calorimeteter components.

  20. Energy resolution studies of liquid argon ionization detectors

    International Nuclear Information System (INIS)

    A gridded ionization chamber was used to study the energy resolution in liquid argon with electrons from a 207Bi radioactive source. Argon was purified in the gas phase with a simple and reliable system, capable of reducing the impurity level below 1 ppb O2 equivalent, as inferred by a pulse shape analysis of the ionization signals. The electron spectrum was measured at different drift fields, up to 10.9 KV/cm. At this maximum field, a total energy resolution of 32 keV (fwhm), corresponding to a noise-subtracted energy resolution of 26 keV (fwhm), was obtained for the 976 keV conversion electron line. This value is the best reported so far in liquid argon but is still a factor of seven worse than the theoretical limit set by the Fano factor. The reasons for this discrepancy are discussed. (orig.)

  1. Liquid Argon Calorimetry with LHC-Performance Specifications

    CERN Multimedia

    2002-01-01

    % RD-3 Liquid Argon Calorimetry with LHC-Performance Specifications \\\\ \\\\Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. Among the techniques used so far, or under development, the liquid argon sampling calorimetry offers high radiation resistence, good energy resolution (electromagnetic and hadronic), excellent calibration stability and response uniformity. Its rate capabilities, however, do not yet match the requirements for LHC. \\\\ \\\\The aim of this proposal is to improve the technique in such a way that high granularity, good hermiticity and adequate rate capabilities are obtained, without compromising the above mentioned properties. To reach this goal, we propose to use a novel structure, the $^{\\prime\\prime}$accordion$^{\\prime\\prime}$, coupled to fast preamplifiers working at liquid argon temperature. Converter and readout electrodes are no longer planar and perpendicular to particles, as usual, but instead they are wiggled around a plane containing particles. ...

  2. On the Electric Breakdown in Liquid Argon at Centimeter Scale

    CERN Document Server

    Auger, M; Ereditato, A; Goeldi, D; Janos, S; Kreslo, I; Luethi, M; von Rohr, C Rudolf; Strauss, T; Weber, M S

    2015-01-01

    We present a study on the dependence of electric breakdown discharge parameters on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  3. Solar-pumped CO laser

    Science.gov (United States)

    Treanor, Charles E.

    This paper describes a method of converting thermal radiation directly into laser radiation at a wavelength of about 5 micrometers. The working fluid for the laser operation is a mixture of carbon monoxide and argon. The source of thermal radiation is assumed to be a solar oven or electrical oven operating in the range of 2000 to 2500 K. The use of carbon monoxide as the lasing material presents the advantage that the absorbing lines can be pressure broadened to permit efficient absorption of the thermal radiation without unacceptable increases in vibrational relaxation. Estimates of the efficiency, size, and power loading of such a laser are discussed.

  4. Laser Peripheral Iridotomy with Iridoplasty in Primary Angle Closure Suspect: Anterior Chamber Analysis by Pentacam

    OpenAIRE

    Lee, Jong Rak; Choi, Jin Young; Kim, Yeon-Deok; Choi, Jaewan

    2011-01-01

    Purpose To compare conventional laser peripheral iridotomy (LPI) and LPI combined with laser peripheral iridoplasty in eyes with primary angle closure suspect (PACS) by assessment of anterior chamber dimensional changes using a Pentacam. Methods Forty-eight eyes of 24 subjects with bilateral PACS were recruited consecutively. Each eye was randomly allocated to treatment with conventional LPI, argon LPI only, or LPI plus iridoplasty, which consisted of simultaneous argon LPI and peripheral iri...

  5. Transscleral diode laser retinopexy in retinal reattachment surgery Retinopexia com laser de diodo transescleral na cirurgia de descolamento de retina

    Directory of Open Access Journals (Sweden)

    João Carlos de Miranda Gonçalves

    2004-02-01

    Full Text Available PURPOSE: Transscleral diode retinal photocoagulation (diopexy is becoming an accepted technique in the treatment of selected retinal diseases. The objective of this study is to evaluate diopexy technique in the production of adhesive chorioretinal lesions during the surgical treatment of the rhegmatogenous retinal detachment. METHODS: 25 patients with rhegmatogenous retinal detachment were enrolled in a prospective clinical-surgical study to evaluate the technique of transscleral diode laser photocoagulation to obtain adhesive chorioretinal lesions during retinal reattachment surgery. The surgery consisted of the placement of an exoplant silicon to produce a buckle effect combined with a drainage of subretinal fluid in most cases. RESULTS: By a mean follow-up of 10 months, 21 of 25 eyes had their retinas reattached after only one surgery with diopexy used in all cases. CONCLUSION: Transscleral diode laser photocoagulation was a technically easy, controlled, effective, reproducible and safe means of obtaining chorioretinal adhesion in retinal reattachment surgery.OBJETIVO: Fotocoagulação transescleral com laser de diodo (diopexia está se tornando técnica utilizada no tratamento de algumas doenças retinianas. O objetivo deste estudo é avaliar a técnica de diopexia na produção de lesões coriorretinianas aderentes durante o tratamento cirúrgico do descolamento de retina regmatogênico. MÉTODOS: Vinte e cinco pacientes com descolamento de retina regmatogênico participaram deste estudo clínico-cirúrgico prospectivo para avaliar a técnica de fotocoagulação com laser de diodo transescleral para obter lesões coriorretinianas aderentes durante a cirurgia de descolamento de retina. A cirurgia consistiu de colocação de explante de silicone para produzir efeito de introflexão escleral combinado com drenagem do líquido subretiniano na maioria dos casos. RESULTADOS: Após um período médio de seguimento de 10 meses, em 21 dos 25 olhos

  6. Two-dimensional ion velocity distribution functions in inductively coupled argon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, David C [Optical Sciences Company, Anaheim, CA 92806 (United States); McWilliams, Roger [Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697 (United States); Edrich, David A [Scientific Applications and Research Associates Inc., Cypress, CA 90630 (United States)

    2005-08-01

    Two-dimensional ion velocity distribution functions (IVDFs) of argon plasmas have been measured with optical tomography via laser-induced fluorescence (LIF). An inductive radio-frequency (RF) coil created the plasmas, and IVDFs were measured versus RF frequency, gas pressure and location (bulk plasma or presheath of a plate). Typical gas pressure was 0.3-0.4 mTorr, RF power 25 W and magnetic field 130 G. Effective perpendicular ion temperature decreased with increasing RF frequency, and changed little with pressure. Optical tomography reveals features of the presheath IVDF that cannot be deduced from LIF scans parallel and perpendicular to the plate alone. Progress also has been made toward performing optical tomography on a commercial ion beam source (Veeco/Ion Tech 3 cm RF Ion Source, Model no. 201). In particular, it has been discovered that the beam energy fluctuates in a range of about 20 eV over the timescale of a few minutes.

  7. The Effect of the Argon Carrier Gas in the Multiphoton Dissociation-Ionization of Tetracene

    Directory of Open Access Journals (Sweden)

    Carmen Cisneros

    2008-10-01

    Full Text Available The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG, has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z. The results show that the dynamic of photodissociation at ~1010 W⋅cm-2 intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the formation of the CHm+ (m = 2, 4, C2H4+ and C5H4+2 ions. CH5+ and CH6+ were observed which have not been reported before in photodissociation tetracene experiments.

  8. Study of collisional and radiatif processes for atmospheric pressure argon plasma in stationary state and quenching

    International Nuclear Information System (INIS)

    The positive column of a wall-stabilized arc burning in argon at atmospheric pressure is studied. In the first part, experimental values of electron and atom number densities are presented. They have been obtained in stationary state and during the arc decay by means of spectroscopy and two wavelengths laser interferometry measurements. The theoretical study has been developed with a collisional-radiative model coupled with the electron energy balance. Electron-ion recombination and ionization coefficients have been calculated solving rate equations. Then the model has been adapted for studying a stationary plasma and the calculated results are in good agreement with the experimental values. The theoretical study of the plasma decay has allowed us to determine the influence of recombination, ionization, diffusion and convection in the evolution of densities and temperatures. Temporal variations of the difference between electron temperature and gas temperature have been explained by analysing the electron energy balance

  9. Vaporization kinetics of Sb2S3 in argon fluid

    Institute of Scientific and Technical Information of China (English)

    杨勇; 华一新

    2003-01-01

    The vaporization kinetics of antimony trisulfide in argon fluid was studied with thermogravimetry at 873- 1 173 K. A theoretical model was developed to calculate the overall rate constant and the mass transfer coefficient ingas phase. The experimental results show that the vaporization rate is enhanced with increasing temperature and ar-gon flow-rate. The evaporation rate is mainly controlled by mass transport in the gas phase. The apparent activationenergy for the process is found to be 55.54 kJ/mol. It is demonstrated that the mass transfer coefficient in gas phaseis decreased with increasing temperature.

  10. Modelling of a supersonic ICP argon-hydrogen expansion

    International Nuclear Information System (INIS)

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

  11. Attosecond-correlated dynamics of two electrons in argon

    Indian Academy of Sciences (India)

    V Sharma; N Camus; B Fischer; M Kremer; A Rudenko; B Bergues; M Kuebel; N G Johnson; M F Kling; T Pfeifer; J Ullrich; R Moshammer

    2014-01-01

    In this work we explored strong field-induced decay of doubly excited transient Coulomb complex Ar** → Ar2++2. We measured the correlated two-electron emission as a function of carrier envelop phase (CEP) of 6 fs pulses in the non-sequential double ionization (NSDI) of argon. Classical model calculations suggest that the intermediate doubly excited Coulomb complex loses memory of its formation dynamics. We estimated the ionization time difference between the two electrons from NSDI of argon and it is 200 ± 100 as (N Camus et al, Phys. Rev. Lett. 108, 073003 (2012)).

  12. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    Science.gov (United States)

    Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

    2013-11-01

    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.

  13. Measurement of the Cotton-Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus

    CERN Document Server

    Mei, Hsien-Hao; Chen, Sheng-Jui; Pan, Sheau-shi

    2008-01-01

    Experiments for vacuum birefringence and vacuum dichroism have set up high-finesse high magnetic experimental apparatuses which are ideal for gaseous Cotton-Mouton effect measurements. PVLAS Collaboration has recently measured Cotton-Mouton effects in krypton, xenon and neon at the wavelength of 1064 nm. In this Letter, we report on our measurement of Cotton-Mouton effects in nitrogen, oxygen, carbon dioxide, argon, and krypton at pressure P = 0.5-300 Torr, temperature T = 295-298 K, and laser wavelength of 1064 nm in a magnetic field B = 2.3 T, using our Q & A experimental setup, which are in agreement with the PVLAS results.

  14. Laser remelting of Ti6AL4V using high power diode laser

    Science.gov (United States)

    Amaya-Vázquez, M. R.; Sánchez-Amaya, J. M.; Boukha, Z.; El Amrani, K.; Botana, F. J.

    2012-04-01

    Titanium alloys present excellent mechanical and corrosion properties, being widely employed in different industries such as medical, aerospace, automotive, petrochemical, nuclear and power generation, etc. Ti6Al4V is the α-β alloy most employed in industry. The modification of its properties can be achieved with convectional heat treatments and/or with laser processing. Laser remelting (LR) is a technology applied to Ti6Al4V by other authors with excimer and Nd-Yag laser with pure argon shielding gas to prevent risk of oxidation. In the present contribution, laser remelting has been applied for the first time to Ti6Al4V with a high power diode laser (with pure argon as shielding gas). Results showed that remelted samples (with medium energy densities) have higher microhardness and better corrosion resistance than Ti6Al4V base metal.

  15. Uranium-liquid argon calorimetry: preliminary results from the DO tests

    International Nuclear Information System (INIS)

    The motivations for using uranium and liquid argon in sampling calorimetry are reviewed and the pros and cons of the technique are discussed. Preliminary results of the DO uranium-liquid argon test program are presented. 9 refs., 7 figs

  16. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    Science.gov (United States)

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

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  17. Measurement of the argon plasma temperature by use of pyrometer

    International Nuclear Information System (INIS)

    The author describes in detail how to use pyrometer to measure the plasma temperature. The temperatures of shock-generated argon plasmas are given in the present work. Measured results of temperature-pressure curve are compared with calculated results using Saha-Debye-Huckel model, which are in good agreement

  18. Turbulence and transport in a magnetized argon plasma

    International Nuclear Information System (INIS)

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

  19. Thermophysical properties of multi-shock compressed dense argon.

    Science.gov (United States)

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

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models. PMID:24559345

  20. Thermal decomposition of Yttrium(III) isovalerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao;

    2016-01-01

    The thermal behaviour of yttrium(III) isovalerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, FTIR-spectroscopy, hot-stage optical microscopy and X-ray diffraction with a laboratory Cu-tube source as well as with a synchrotron radiation source...

  1. Thermal decomposition of yttrium(III) valerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao;

    2014-01-01

    The thermal decomposition of yttrium(III) valerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction, in-situ synchrotron diffraction and hot-stage microscopy as well as room temperature optical microscopy. Melting...

  2. Thermal decomposition of yttrium(III) hexanoate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Suarez Guevara, Maria Josefina; Attique, Fahmida;

    2015-01-01

    The thermal decomposition of yttrium(III) hexanoate (Y(C5H11CO2)3)·xH2O in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction at a laboratory Cu-tube source and in-situ experiments at a synchrotron radiation source as well as hot...

  3. A 2-Dimensional Fluid Model for an Argon Rf Discharge

    NARCIS (Netherlands)

    Passchier, J. D. P.; W. J. Goedheer,

    1993-01-01

    A fluid model for an argon rf discharge in a cylindrical discharge chamber is presented. The model contains the particle balances for electrons and ions and the electron energy balance. A nonzero autobias voltage is obtained by imposing the condition that the time-averaged current toward the powered

  4. Study of Liquid Argon Dopants for LHC Hadron Calorimetry

    CERN Multimedia

    2002-01-01

    Hadron calorimetry based on the Liquid Argon Ionisation Chamber technique is one of the choice techniques for LHC-experimentation. A systematic study of the effect of selected dopants on Liquid Argon (LAr) will be carried out with the aim to achieve an improvement on: \\item (i)~``Fast Liquid Argon'' search and study of dopants to increase the drift velocity. It has been already shown that CH&sub4. added at a fraction of one percent increases the drift velocity by a factor of two or more. \\item (ii)~``Compensated Liquid Argon'' search and study of dopants to increase the response to densely ionising particles, resulting in improved compensation, such as photosensitive dopants. \\end{enumerate}\\\\ \\\\ Monitoring of the parameters involved in understanding the response of a calorimeter is essential. In case of doped LAr, the charge yield, the non-saturated drift velocity and the electron lifetime in the liquid should be precisely and simultaneously monitored as they all vary with the level of dopant concentrati...

  5. LArGe. A liquid argon scintillation veto for GERDA

    International Nuclear Information System (INIS)

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in 76Ge, by operating naked germanium detectors submersed into 65 m3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 103 have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10-2 cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural 42Ar abundance (in parallel to Gerda), and have indication for the 2νββ-decay in natural germanium. (orig.)

  6. LArGe. A liquid argon scintillation veto for GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Heisel, Mark

    2011-04-13

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in {sup 76}Ge, by operating naked germanium detectors submersed into 65 m{sup 3} of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m{sup 3} (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10{sup -2} cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural {sup 42}Ar abundance (in parallel to Gerda), and have indication for the 2{nu}{beta}{beta}-decay in natural germanium. (orig.)

  7. Design of capsules capable of argon-filling

    International Nuclear Information System (INIS)

    The possibility of the use of polycarbosilane capsules as fuel container in inertial confinement fusion experiments was analyzed in the paper. Primary study indicates that the polycarbosilane capsules can be filled with argon by means of diffusion and possess reasonable retention time for deuterium. (author)

  8. Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

    Science.gov (United States)

    M, N. Stankov; A, P. Jovanović; V, Lj Marković; S, N. Stamenković

    2016-01-01

    The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approximate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by ions, produced by atomic-to-molecular conversion of Ar+ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as conversion maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional (1D) model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional (2D) model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes. Project supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. ON171025).

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

    International Nuclear Information System (INIS)

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

  10. Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy

    Science.gov (United States)

    Wang, Jenny; Huie, Philip; Dalal, Roopa; Lee, Seungjun; Tan, Gavin; Lee, Daeyoung; Lavinksy, Daniel; Palanker, Daniel

    2016-03-01

    Unlike conventional photocoagulation, non-damaging retinal laser therapy (NRT) limits laser-induced heating to stay below the retinal damage threshold and therefore requires careful dosimetry. Without the adverse effects associated with photocoagulation, NRT can be applied to critical areas of the retina and repeatedly to manage chronic disorders. Although the clinical benefits of NRT have been demonstrated, the mechanism of therapeutic effect and width of the therapeutic window below damage threshold are not well understood. Here, we measure activation of heat shock response via laser-induced hyperthermia as one indication of cellular response. A 577 nm laser is used with the Endpoint Management (EpM) user interface, a titration algorithm, to set experimental pulse energies relative to a barely visible titration lesion. Live/dead staining and histology show that the retinal damage threshold in rabbits is at 40% of titration energy on EpM scale. Heat shock protein 70 (HSP70) expression in the retinal pigment epithelium (RPE) was detected by whole-mount immunohistochemistry after different levels of laser treatment. We show HSP70 expression in the RPE beginning at 25% of titration energy indicating that there is a window for NRT between 25% and 40% with activation of the heat shock protein expression in response to hyperthermia. HSP70 expression is also seen at the perimeter of damaging lesions, as expected based on a computational model of laser heating. Expression area for each pulse energy setting varied between laser spots due to pigmentation changes, indicating the relatively narrow window of non-damaging activation and highlighting the importance of proper titration.

  11. Industrial laser use in Navy depots

    Science.gov (United States)

    Alker, Julius

    The applications of industrial lasers used at the U.S. Navy depots are reviewed. Consideration is given to a method of aircraft laser depainting using vehicles with a laser vision system to determine the composition of the target area and the use of a 1.5 kW Nd:YAG laser for spot welding engine heat shields. For repairing jet engine combustion chambers, a 5-W argon ion laser beam provides light by fiber optics for a three-dimensional vision system and a 1.5 kW CO2 laser cutter is used to remove damaged parts. The development of a three-dimensional weld seam tracking system and the Naval Sea Systems Command to plot ship layouts using class I IR photodiode lasers is examined. Also, the use of IR high pulse rate photodiode laser and camera measuring system for measuring and shaping propellers is discussed.

  12. INFRARED DIODE LASER RETINAL TREATMENT FOR CHRONIC HEADACHE

    Directory of Open Access Journals (Sweden)

    Subba Rao

    2013-12-01

    Full Text Available ABSTRACT: Nearly 60 to 70 crores of people all over the world are suffering from various types of chronic headache. This is one of the commonest medical problems. To get relief from headache various medical treatments are used with little success. The aim of our study is to give permanent treatment to chronic headache patients by using infrared diode laser selective retinal photocoagulati on. NIDEK infrared diode laser with NIDEK SL40 slit - lamp and NIDEK digital fundus camera for retinal evaluation, MAINSTER 135D lens for laser beam focusing and retinal examination and TOPCON non - contact tonometer for intra ocular pressure measurements are used. Diode laser is chosen because of its deep penetration into all the layers of retina and choroid. 500 cases of chronic headache were studied. Laser photocoagulation was given in selective areas of retina in 2 to 3 sessions with 15 days interval. 10 to 60 years age group were studied. 90% of patients who got laser treatment are relieved from their headache in severity and in frequency. 80% of patients needed 2 sittings and 20% of patients needed 3 sittings. 70% of patients got relief from headache by fi rst sitting itself. 50% of patients are not only relieved from their headaches but also noticed visual clarity improvement. Retinal ischaemia is one of the main cause for ocular pain and headache. Laser treatment will improve circulation by reducing ischae mia thereby relieves ocular pain and headache

  13. EFFECTS OF ARGON ON THE PROPERTIES OF RF SPUTTERED AMORPHOUS SILICON

    OpenAIRE

    Shao-Qi, Peng; Qai, Yu; Xian, Zhang; Jing, Ye

    1981-01-01

    The Effects of argon on the properties of rf sputtered amorphous silicon film have been investigated. As the sputtering argon pressure is increased from 2 to 20 mTorr, the content of argon in the amorphous silicon film increases apparently (Argon/Silicon : from 10-2 to 5 x 10-2). The other properties measured as a function of argon pressure PAr show that as the PAr is increased, the photoconductivity, resistivity (300K), conductivity activation energy and optical gap increase also, while the ...

  14. A semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Naoko, O.; Khiroiti, S.

    1984-05-20

    An improved method is patented for increasing the service life of semiconductor lasers which does not hinder their characteristics, by applying a protective film to the end planes of the optical resonator of the laser. It is recommended that a mixture of an A1203 dielectric and an inert element such as argon be used for a GaAs, GaA1As laser as the protective film. The radii of gallium and arsenic atoms are equal to 1.24 and 1.25 angstroms, respectively. The radii of A1, O and Si atoms which make up the protective film are equal to 1.43, .61 and 1.17 angstroms, respectively. The radius of the argon atoms in the protective film, which is equal to 1.91 angstroms) is high compared to the atoms noted above. As a result, the movement of the gallium and arsenic atoms, which causes a drop in later characteristics during operation, is made more difficult.

  15. Laser frequency bandwidth narrowing by photorefractive two-beam coupling.

    Science.gov (United States)

    Chomsky, D; Sternklar, S; Zigler, A; Jackel, S

    1992-04-01

    We present a theoretical analysis and experimental demonstration of a new method for spectral narrowing of laser radiation. The bandwidth narrowing is experienced by a laser beam subjected to a photorefractive two-beam coupling process. Contrary to the conventional method of frequency filtering by a Fabry-Perot étalon, this technique has no intrinsic finesse limitation on its resolution. A factor of 2 in frequency bandwidth narrowing is achieved with an argon-ion laser.

  16. Evaluation of the TA combined with Panretinal photocoagulation in treating the diabetic macular edema%TA联合全视网膜光凝治疗糖尿病性黄斑水肿的效果评价

    Institute of Scientific and Technical Information of China (English)

    孟晶; 张旭; 张日佳; 李诗娜; 李水莲

    2012-01-01

    statistical analysis methods by the SPSS data applications,including the t-test,the direct probability calculation,and repeated design analysis of variance. Results The average best corrected visual acuity in the combined treatment group were higher than the PRP treatment group 3 months and 6 months after treatment (P<0.05).The RNV leakage area was significantly lower in the combined treatment group after treatment of 1 month and 3 months (P <0.05),but was not significant after 6 months (P>0.05).The macular retinal thickness values lowered in the joint group after 1 month,3 months,6 months (P<0.05).The combined treatment group required lower laser energy than the PRP treatment group (P<0.01).The IOP in both groups were no different (P>0.05). Conclusions Intravitreal injection of TA combined with all retinal photocoagulation is a good way in treat the diabetic macular edema,which can reduce the energy needed for PRP,reduce the delay edema,and improve vision,which is a worthy recommendation in treating the diabetic macular edema.

  17. LASER-ASSISTED e-Ar SCATTERING INCO2 LASER FIELD

    Institute of Scientific and Technical Information of China (English)

    Zhu Zun-lue; Jiang Yu-hai; Sun Jin-feng

    2000-01-01

    Electron scattering from argon in a laser field is investigatedempolying the second-order perturbation theory. The absolutedifferential cross sections of e-Ar scattering with multiphoton exchangein special scattering geometries G1 (for small-angle scattering) and G2are calculated. Our results are found to be better than othertheoretical results as compared with the experimental data.

  18. Spectra of heliumlike carbon, aluminium and argon under strongly coupled plasma

    International Nuclear Information System (INIS)

    Spectral line positions for the highly stripped helium like carbon, aluminium and argon embedded in intense plasma environments have been calculated theoretically to compare with the existing data available from laser plasma experiments. The changes in the ionization potentials for such ions have been determined and the excitation energies, oscillator strengths and transition probabilities for the transitions 1s2 1S → 1snp 1P (n 2-5) have been evaluated for the diagnostic determination of such plasmas. The ion sphere (IS) model was used for estimating the effect of strongly coupled plasma on the ions within the non-relativistic as well as the relativistic framework. Time dependent perturbation theory has been applied for obtaining the linear response properties of the ions in the non-relativistic approximation. The effects of the plasma environment on such properties of the ions under the Debye screening model with suitable cut off radii have also been considered for comparing the data with those obtained from the IS model of the plasma. These results show that the IS model seems to be a viable method for predicting the data obtained from experiments involving strongly coupled plasmas generated in laser produced Icf plasmas

  19. Spectra of heliumlike carbon, aluminium and argon under strongly coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sil, A. [Heidelberg Univ., Theoretische Chemie (Germany); Anton, J. [Ulm Univ., Institut fur Elektrochemie (Germany); Fritzsche, S. [Gesellschaft fur Schwerionenforschung Darmstadt, Darmstadt (Germany); Mukherjee, P.K. [Indian Association for the Cultivation of Science, Jadavpur, Kolkata (India); Ramakrishna Mission Vivekananda Univ., West Bengal (India); Fricke, B. [Kassel Univ., Institut fur Physik (Germany)

    2009-12-15

    Spectral line positions for the highly stripped helium like carbon, aluminium and argon embedded in intense plasma environments have been calculated theoretically to compare with the existing data available from laser plasma experiments. The changes in the ionization potentials for such ions have been determined and the excitation energies, oscillator strengths and transition probabilities for the transitions 1s{sup 2} 1S -> 1snp {sup 1}P (n 2-5) have been evaluated for the diagnostic determination of such plasmas. The ion sphere (IS) model was used for estimating the effect of strongly coupled plasma on the ions within the non-relativistic as well as the relativistic framework. Time dependent perturbation theory has been applied for obtaining the linear response properties of the ions in the non-relativistic approximation. The effects of the plasma environment on such properties of the ions under the Debye screening model with suitable cut off radii have also been considered for comparing the data with those obtained from the IS model of the plasma. These results show that the IS model seems to be a viable method for predicting the data obtained from experiments involving strongly coupled plasmas generated in laser produced Icf plasmas

  20. Evaporation and condensation at a liquid surface. I. Argon

    Science.gov (United States)

    Yasuoka, Kenji; Matsumoto, Mitsuhiro; Kataoka, Yosuke

    1994-11-01

    Molecular dynamics computer simulations were carried out to investigate the dynamics of evaporation and condensation for argon at the temperature of 80 and 100 K. From the decrease of the survival probability of vapor molecules, the ratio of self reflection to collision is estimated to be 12%-15%, only weakly dependent on the temperature. This suggests that argon vapor molecules are in the condition of almost complete capture, and the condensation is considered to be a barrierless process. The total ratio of reflection which is evaluated with the flux correlation of condensation and evaporation is 20% at both temperature. The difference between these two ratios of reflection is ascribed to a phenomenon that vapor molecules colliding with the surface drive out other liquid molecules. This molecule exchange at the surface is as important as the self-reflection, and the conventional picture of condensation as a unimolecular chemical reaction is not appropriate.

  1. The Erosion of Frozen Argon by Swift Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Graversen, O.;

    1981-01-01

    The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore unequivo......The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore...... unequivocally associated with electronic processes generated by the bombarding particle. In the present energy region, it is found that Y scales approximately as the electronic stopping power squared, depends on the charge state of the incoming helium ions, and perhaps more important, is independent...

  2. Demonstration of a Lightguide Detector for Liquid Argon TPCs

    CERN Document Server

    Bugel, L; Ignarra, C; Jones, B J P; Katori, T; Smidt, T; Tanaka, H -K

    2011-01-01

    We report demonstration of light detection in liquid argon using an acrylic lightguide detector system. This opens the opportunity for development of an inexpensive, large-area light collection system for large liquid argon time projection chambers. The guides are constructed of acrylic, with TPB embedded in a surface coating with a matching index of refraction. We study the response to early scintillation light produced by a 5.3 MeV alpha. We measure coating responses from 7 to 8 PE on average, compared to an ideal expectation of 10 PE on average. We estimate the attenuation length of light along the lightguide bar to be greater than 0.5 m. The coating response and the attenuation length can be improved; we show, however, that these results are already sufficient for triggering in a large detector.

  3. Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator

    International Nuclear Information System (INIS)

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

  4. Readiness of the ATLAS Liquid Argon Calorimeter for LHC Collisions

    CERN Document Server

    Aad, G; Abdallah, J; Abdelalim, A A; Abdesselam, A; Abdinov, O; Abi, B; Abolins, M; Abramowicz, H; Abreu, H; Acharya, B S; Adams, D L; Addy, T N; Adelman, J; Adorisio, C; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, J A; Aharrouche, M; Ahlen, S P; Ahles, F; Ahmad, A; Ahmed, H; Ahsan, M; Aielli, G; Akdogan, T; Åkesson, T P A; Akimoto, G; Akimov, A V; Aktas, A; Alam, M S; Alam, M A; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Aliyev, M; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alviggi, M G; Amako, K; Amelung, C; Ammosov, V V; Amorim, A; Amorós, G; Amram, N; Anastopoulos, C; Andeen, T; Anders, C F; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angerami, A; Anghinolfi, F; Anjos, N; Antonaki, A; Antonelli, M; Antonelli, S; Antunovic, B; Anulli, F; Aoun, S; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Archambault, J P; Arfaoui, S; Arguin, J-F; Argyropoulos, T; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnault, C; Artamonov, A; Arutinov, D; Asai, M; Asai, S; Asfandiyarov, R; Ask, S; Åsman, B; Asner, D; Asquith, L; Assamagan, K; Astbury, A; Astvatsatourov, A; Atoian, G; Auerbach, B; Auge, E; Augsten, K; Aurousseau, M; Austin, N; Avolio, G; Avramidou, R; Axen, D; Ay, C; Azuelos, G; Azuma, Y; Baak, M A; Baccaglioni, G; Bacci, C; Bach, A; Bachacou, H; Bachas, K; Backes, M; Badescu, E; Bagnaia, P; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, M D; Baltasar Dos Santos Pedrosa, F; Banas, E; Banerjee, P; Banerjee, S; Banfi, D; Bangert, A; Bansal, V; Baranov, S P; Baranov, S; Barashkou, A; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baron, S; Baroncelli, A; Barr, A J; Barreiro, F; BarreiroGuimarães da Costa, J; Barrillon, P; Barros, N; Bartoldus, R; Bartsch, D; Bastos, J; Bates, R L; Bathe, S; Batkova, L; Batley, J R; Battaglia, A; Battistin, M; Bauer, F; Bawa, H S; Bazalova, M; Beare, B; Beau, T; Beauchemin, P H; Beccherle, R; Becerici, N; Bechtle, P; Beck, G A; Beck, H P; Beckingham, M; Becks, K H; Bedajanek, I; Beddall, A J; Beddall, A; Bednár, P; Bednyakov, V A; Bee, C; Begel, M; Behar Harpaz, S; Behera, P K; Beimforde, M; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellina, F; Bellomo, M; Belloni, A; Belotskiy, K; Beltramello, O; Ben Ami, S; Benary, O; Benchekroun, D; Bendel, M; Benedict, B H; Benekos, N; Benhammou, Y; Benincasa, G P; Benjamin, D P; Benoit, M; Bensinger, J R; Benslama, K; Bentvelsen, S; Beretta, M; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernardet, K; Bernat, P; Bernhard, R; Bernius, C; Berry, T; Bertin, A; Besson, N; Bethke, S; Bianchi, R M; Bianco, M; Biebel, O; Biesiada, J; Biglietti, M; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biscarat, C; Bitenc, U; Black, K M; Blair, R E; Blanchard, J-B; Blanchot, G; Blocker, C; Blocki, J; Blondel, A; Blum, W; Blumenschein, U; Bobbink, G J; Bocci, A; Boehler, M; Boek, J; Boelaert, N; Böser, S; Bogaerts, J A; Bogouch, A; Bohm, C; Bohm, J; Boisvert, V; Bold, T; Boldea, V; Boldyrev, A; Bondarenko, V G; Bondioli, M; Boonekamp, M; Booth, J R A; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borjanovic, I; Borroni, S; Bos, K; Boscherini, D; Bosman, M; Bosteels, M; Boterenbrood, H; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boulahouache, C; Bourdarios, C; Boyd, J; Boyko, I R; Bozovic-Jelisavcic, I; Bracinik, J; Braem, A; Branchini, P; Brandenburg, G W; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brelier, B; Bremer, J; Brenner, R; Bressler, S; Breton, D; Brett, N D; Britton, D; Brochu, F M; Brock, I; Brock, R; Brodbeck, T J; Brodet, E; Broggi, F; Bromberg, C; Brooijmans, G; Brooks, W K; Brown, G; Brubaker, E; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Buanes, T; Bucci, F; Buchanan, J; Buchholz, P; Buckley, A G; Budagov, I A; Budick, B; Büscher, V; Bugge, L; Bulekov, O; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Bussey, P; Buszello, C P; Butin, F; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Byatt, T; Caballero, J; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G; Calfayan, P; Calkins, R; Caloba, L P; Caloi, R; Calvet, D; Camarri, P; Cambiaghi, M; Cameron, D; Campabadal-Segura, F; Campana, S; Campanelli, M; Canale, V; Canelli, F; Canepa, A; Cantero, J; Capasso, L; Capeans-Garrido, M D M; Caprini, I; Caprini, M; Capua, M; Caputo, R; Caracinha, D; Caramarcu, C; Cardarelli, R; Carli, T; Carlino, G; Carminati, L; Caron, B; Caron, S; Carrillo Montoya, G D; Carron Montero, S; Carter, A A; Carter, J R; Carvalho, J; Casadei, D; Casado, M P; Cascella, M; Caso, C; Castaneda Hernadez, A M; Castaneda-Miranda, E; Castillo Gimenez, V; Castro, N; Cataldi, G; Catinaccio, A; Catmore, J R; 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Cogneras, E; Cojocaru, C D; Colas, J; Cole, B; Colijn, A P; Collard, C; Collins, N J; Collins-Tooth, C; Collot, J; Colon, G; Coluccia, R; Conde Muiño, P; Coniavitis, E; Consonni, M; Constantinescu, S; Conta, C; Conventi, F; Cook, J; Cooke, M; Cooper, B D; Cooper-Sarkar, A M; Cooper-Smith, N J; Copic, K; Cornelissen, T; Corradi, M; Corriveau, F; Corso-Radu, A; Cortes-Gonzalez, A; Cortiana, G; Costa, G; Costa, M J; Costanzo, D; Costin, T; Côté, D; Coura Torres, R; Courneyea, L; Cowan, G; Cowden, C; Cox, B E; Cranmer, K; Cranshaw, J; Cristinziani, M; Crosetti, G; Crupi, R; Crépé-Renaudin, S; Cuenca Almenar, C; Cuhadar Donszelmann, T; Curatolo, M; Curtis, C J; Cwetanski, P; Czyczula, Z; D'Auria, S; D'Onofrio, M; D'Orazio, A; Da Silva, P V M; Da Via, C; Dabrowski, W; Dai, T; Dallapiccola, C; Dallison, S J; Daly, C H; Dam, M; Danielsson, H O; Dannheim, D; Dao, V; Darbo, G; Darlea, G L; Davey, W; Davidek, T; Davidson, N; Davidson, R; Davison, A R; Dawson, I; Dawson, J W; Daya, R K; De, K; de Asmundis, R; 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Zitoun, R; Zivkovic, L; Zmouchko, V V; Zobernig, G; Zoccoli, A; zur Nedden, M; Zutshi, V

    2010-01-01

    The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along eta (averaged over phi) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained u...

  5. Breakdown voltage of metal-oxide resistors in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Bagby, L. F. [Fermilab; Gollapinni, S. [Kansas State U.; James, C. C. [Fermilab; Jones, B. J.P. [MIT; Jostlein, H. [Fermilab; Lockwitz, S. [Fermilab; Naples, D. [Pittsburgh U.; Raaf, J. L. [Fermilab; Rameika, R. [Fermilab; Schukraft, A. [Fermilab; Strauss, T. [Bern U., LHEP; Weber, M. S. [Bern U., LHEP; Wolbers, S. A. [Fermilab

    2014-11-07

    We characterized a sample of metal-oxide resistors and measured their breakdown voltage in liquid argon by applying high voltage (HV) pulses over a 3 second period. This test mimics the situation in a HV-divider chain when a breakdown occurs and the voltage across resistors rapidly rise from the static value to much higher values. All resistors had higher breakdown voltages in liquid argon than their vendor ratings in air at room temperature. Failure modes range from full destruction to coating damage. In cases where breakdown was not catastrophic, subsequent breakdown voltages were lower in subsequent measuring runs. One resistor type withstands 131 kV pulses, the limit of the test setup.

  6. A pressurized argon gas TPC as DUNE near detector

    CERN Document Server

    Martin-Albo, J

    2016-01-01

    DUNE is a new international experiment for neutrino physics and nucleon decay searches. It will consist of two detectors, about 1300 km apart, exposed to a multi-megawatt neutrino beam that will be built at Fermilab. One of the two detectors will be installed several hundred meters downstream of the neutrino production point with the primary role of characterising the energy spectrum and composition of the beam as well as performing precision measurements of neutrino cross sections. For the design of this so-called near detector, the DUNE Collaboration is considering, among other technologies, a pressurized argon gas time projection chamber. Such a detector, thanks to its low density and low detection thresholds, would allow the detailed measurement in argon of nuclear effects at the neutrino interaction vertex, which are considered at present one of the most important sources of systematic uncertainty for neutrino oscillation measurements.

  7. Opacity measurements in shock-generated argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D.

    1993-07-01

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

  8. Development of cryogenic installations for large liquid argon neutrino detectors

    CERN Document Server

    Adamowski, M; Geynisman, M; Hentschel, S; Montanari, D; Nessi, M; Norris, B

    2015-01-01

    A proposal for a very large liquid argon (68,000 kg) based neutrino detector is being studied. To validate the design principles and the detector technology, and to gain experience in the development of the cryostats and the cryogenic systems needed for such large experiments, several smaller scale installations will be developed and implemented, at Fermilab and CERN. The cryogenic systems for these installations will be developed, constructed, installed and commissioned by an international engineering team. These installations shall bring the required cooling power under specific conditions to the experiments for the initial cool-down and the long term operation, and shall also guarantee the correct distribution of the cooling power within the cryostats to ensure a homogeneous temperature distribution within the cryostat itself. The cryogenic systems shall also include gaseous and liquid phase argon purification devices to be used to reach and maintain the very stringent purity requirements needed for these...

  9. Spectroscopy of Argon Excited in an Electron Beam Ion Trap

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E

    2005-04-18

    Argon is one of the gases best investigated and most widely used in plasma discharge devices for a multitude of applications that range from wavelength reference standards to controlled fusion experiments. Reviewing atomic physics and spectroscopic problems in various ionization stages of Ar, the past use and future options of employing an electron beam ion trap (EBIT) for better and more complete Ar data in the x-ray, EUV and visible spectral ranges are discussed.

  10. Influence of argon pollution on the weld surface morphology

    OpenAIRE

    Krolczyk, G.M.; Nieslony, P.; Krolczyk, J.B.; I. Samardzic; Legutko, S.; S. Hloch; Barrans, Simon; Maruda, R.W.

    2015-01-01

    In this paper the surfaces of butt welded joints in steel tubes were analyzed using an optical 3D measurement system to determine the morphology and topographic parameters. It was established that pollution of the argon shield gas with oxygen did not influence the width of the heat-affected zone. However, the composition of the shield gas significantly influenced the surface asymmetry, Ssk, and its inclination Sku. The measurement of these parameters enabled the selection of a ...

  11. STATUS OF THE ATLAS LIQUID ARGON CALORIMETER AND ITS PERFORMANCE

    CERN Document Server

    Berillari, T; The ATLAS collaboration

    2011-01-01

    The liquid argon (LAr) calorimeters are used in ATLAS for all electromagnetic and for hadron calorimetry. The LAr calorimeter system consists of an electromagnetic barrel calorimeter and two endcaps with electromagnetic, hadronic and forward calorimeters. The latest status of the detector as well as problems and solutions addressed during the last years will be presented. Aspects of operation of a large detector over a long time period will be summarized and selected topics showing the performance of the detector will be shown.

  12. Thermal decomposition of lanthanum(III) butyrate in argon atmosphere

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Xiao, Tang;

    2013-01-01

    The thermal decomposition of La(C3H7CO2)3·xH2O (x≈0.82) was studied in argon during heating at 5K/min. After the loss of bound H2O, the anhydrous butyrate presents at 135°C a phase transition to a mesophase, which turns to an isotropic liquid at 180°C. The decomposition of the anhydrous butyrate ...

  13. Operational performance of a large liquid argon photon calorimeter

    International Nuclear Information System (INIS)

    We describe the performance of a large (0.9x1.4 m2) liquid argon photon calorimeter in high energy experiments at Fermilab. Resolutions for π0 and electron showers, obtained under data-taking conditions, are compared with electron-beam calibration results. Exceptional spatial and time resolutions have been achieved for isolated showers (sigmasub(x,y)0 data up to 180 GeV are presented. (orig.)

  14. Unified set of atomic transition probabilities for neutral argon

    OpenAIRE

    Wiese, W.; Brault, J.; Danzmann, K.; Helbig, V.; de Kock, M

    1989-01-01

    The atomic transition probabilities and radiative lifetimes of neutral argon have been the subject of numerous experiments and calculations, but the results exhibit many discrepancies and inconsistencies. We present a unified set of atomic transition probabilities, which is consistent with essentially all recent results, albeit sometimes only after critical reanalysis. The data consistency and scale confirmation has been achieved in two ways. (i) We have carried out some lifetime–branching-ra...

  15. Monte Carlo Simulation of Argon in Nano-Space

    Institute of Scientific and Technical Information of China (English)

    CHEN Min; YANG Chun; GUO Zeng-Yuan

    2000-01-01

    Monte Carlo simulations are performed to investigate the thermodynamic properties of argon confined in nano-scale cubes constructed of graphite walls. A remarkable depression of the system pressures is observed. The simulations reveal that the length-scale of the cube, the magnitude of the interaction between the fluid and the graphite wall and the density of the fluid exhibit reasonable effects on the thermodynamic property shifts of the luid.

  16. A comparative study to evaluate the effect of fluoride releasing sealant cured by visible light, argon laers, and light emitting diode curing units: An in vitro study

    Directory of Open Access Journals (Sweden)

    Das U

    2009-09-01

    Full Text Available In Pediatric Dentistry, the use of pit and fissure sealant is one of the essential forms of prevention. Pit and fissure caries may be substantially decreased by obliteration of these developmental defects in occlusal, buccal and lingual surfaces with resin based dental sealants. Visible light-curing units, or LCUs, are an integral part of modern adhesive dentistry" They are used to cure resin based composite restoration materials, resin modified glass-ionomer and pit and fissure sealants, as well as to bond orthodontic teeth. Most recently, the argon laser has been approved for initiating the setting reaction with visible light cured-resins. Argon curing of resin materials has been show to enhance the physical properties and degree of polymerization of the resin, while reducing the polymerization time by 75 percent. The study is undertaken considering the inadequate research reports of regarding the comparison of curing ability using argon laser. LEDs and visible light as well as the resistant towards caries activity of the preventive fluoride releasing pit and fissure sealant cured by above mentioned curing units.

  17. DOE Center of Excellence in Medical Laser Applications. Final report, December 1, 1994--November 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L.

    1998-01-01

    An engineering network of collaborating medical laser laboratories are developing laser and optical technologies for medical diagnosis and therapy and are translating the engineering into medical centers in Portland OR, Houston TX, and Galveston TX. The Center includes the University of Texas M.D. Anderson Cancer Center, the University of Texas-Austin, Texas A and M University, Rice University, the University Texas Medical Branch-Galveston, Oregon Medical Laser Center (Providence St. Vincent Medical Center, Oregon Health Sciences University, and Oregon Graduate Institute, Portland, OR), and the University of Oregon. Diagnostics include reflectance, fluorescence, Raman IR, laser photoacoustics, optical coherence tomography, and several new video techniques for spectroscopy and imaging. Therapies include photocoagulation therapy, laser welding, pulsed laser ablation, and light-activated chemotherapy of cancer (photodynamic therapy, or PDT). Medical applications reaching the clinic include optical monitoring of hyperbilirubinemia in newborns, fluorescence detection of cervical dysplasia, laser thrombolysis of blood clots in heart attack and brain stroke, photothermal coagulant of benign prostate hyperplasia, and PDT for both veterinary and human cancer. New technologies include laser optoacoustic imaging of breast tumors and hemorrhage in head trauma and brain stroke, quality control monitoring of dosimetry during PDT for esophageal and lung cancer, polarization video reflectometry of skin cancer, laser welding of artificial tissue replacements, and feedback control of laser welding.

  18. Two dimensional condensation of argon adsorbed on lamellar halides

    International Nuclear Information System (INIS)

    Lamellar halides such as NiCl2, FeCl2, NiBr2, MnBr2, MgBr2, CdBr2, CoI2, FeI2, MnI2, CaI2 and PbI2 were sublimed in a rapid stream of dry nitrogen. The adsorption of argon on such materials shows stepped isotherms which reveal two dimensional condensations. From sets of isotherms the Helmholtz free energy, the internal energy and the entropy of the successive layers are determined. From the entropy of the first layer the role of the potential relief of the adsorbent surface on the structure of the adsorbed layer may be determined while the Helmholtz free energy reveals how the ionic character of the adsorbent governs the attractive force of adsorption. The study of the second third and fourth layers shows that their growth follows quite a different behaviour depending on whether the Van der Waals diameter of argon is greater or smaller than the distance between adjacent anions on the crystal surface. A proposition is made to account for the difference in the critical temperatures of the first and second dense layers in terms of the vibrationnal state of their respective substrate. The occurence for the maximum critical temperature observed of corresponding to a triangular layer 3% more expanded than the (111) plane of solid argon is discussed

  19. A liquid argon scintillation veto for the Gerda experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wegmann, Anne [Max-Planck Institut fuer Kernphysik, Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    Gerda is an experiment to search for the neutrinoless double beta decay of {sup 76}Ge. Bare germanium detectors are operated in a cryostat with 65 m{sup 3} of liquid argon (LAr). To reach the aspired background index of ≤10{sup -3} cts/(keV.kg.yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). A light instrumentation of LAr installed in the LArGe test facility has demonstrated that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. Based on these results, Gerda pursues several options for the light instrumentation, which have to be compatible with the stringent radiopurity requirements of the experiment and should provide a significant suppression of the background in the region of interest around Q{sub ββ} at 2039 keV. This talk gives an account of the competing design options under investigation in the Gerda collaboration. The design options using photomultiplier tubes (PMT) and silicon photomultipliers (SiPM) are discussed, together with their expected performance from Monte Carlo simulations. In addition, the progress of development is reported, along with the design criteria for light instrumentation in Gerda.

  20. A liquid argon scintillation veto for the Gerda experiment

    International Nuclear Information System (INIS)

    Gerda is an experiment to search for the neutrinoless double beta decay of 76Ge. Bare germanium detectors are operated in a cryostat with 65 m3 of liquid argon (LAr). To reach the aspired background index of ≤10-3 cts/(keV.kg.yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). A light instrumentation of LAr installed in the LArGe test facility has demonstrated that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. Based on these results, Gerda pursues several options for the light instrumentation, which have to be compatible with the stringent radiopurity requirements of the experiment and should provide a significant suppression of the background in the region of interest around Qββ at 2039 keV. This talk gives an account of the competing design options under investigation in the Gerda collaboration. The design options using photomultiplier tubes (PMT) and silicon photomultipliers (SiPM) are discussed, together with their expected performance from Monte Carlo simulations. In addition, the progress of development is reported, along with the design criteria for light instrumentation in Gerda.

  1. Space-charge effects in liquid argon ionization chambers

    Science.gov (United States)

    Rutherfoord, J. P.; Walker, R. B.

    2015-03-01

    We have uniformly irradiated liquid argon ionization chambers with betas from high-activity 90Sr sources. The radiation environment is similar to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider (LHC). We measured the resulting ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. In particular they indicate a stability at the 0.1% level for these calorimeters over years of operation at the full LHC luminosity when operated in the normal mode at an electric field E = 1.0 kV / mm. We can operate these chambers in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. This transition point is parameterized by a positive argon ion mobility of μ+ = 0.08 ± 0.02mm2 / V s at a temperature of 88.0±0.5 K and at a pressure of 1.02±0.02 bar. In the space-charge limited regime the ionization currents are degraded and show signs of instability. At the highest electric fields in our study (6.7 kV/mm) the ionization current is still slowly rising with increasing electric field.

  2. ARAPUCA a new device for liquid argon scintillation light detection

    International Nuclear Information System (INIS)

    We present a totally innovative device for the detection of liquid argon scintillation light, that has been named ARAPUCA (Argon R and D Advanced Program at UniCAmp). It is composed of a passive light collector and of active devices. The latters are standard SiPMs that operate at liquid argon temperature, while the passive collector is based on a new technology, never explored in this field before. It is a photon trap, that allows to collect light with extremely high efficiency. The total detection efficiency of the device can be tuned by modifying the ratio between the area of the active devices (SiPM) and the area of the optical window. For example, it will allow to reach a detection efficiency at the level of 1% on a surface of 50 × 50 cm2 with an active coverage of 2 × 2 cm2 (two/three large area SiPM). It is also a cheap device, since the major part of its cost is represented by the active devices. For these reason this appears to be the ideal device for scintillation light detection in large Time Projection Chambers. With appropriate modifications it can be used also in next generation Dark Matter detectors

  3. Isotopic fractionation of argon during stepwise release from shungite

    International Nuclear Information System (INIS)

    In previous attempts to determine the 40Ar/36Ar ratio in the ancient atmosphere, the only direct measurement yielding a value below the atmospheric value of today is for argon released at low temperatures from a pre-Cambrian shungite, an amorphous carbon mineral The present work confirms a low value for 40Ar/36Ar in gas released from a type I shungite at low temperatures. But quantitative scrutiny of the accompanying 38AR/36Ar ratios and the enhanced ratio of 40Ar/36Ar for the fractions released at high temperatures shows convincingly that the effect seen here is an artifact of the stepwise heating and the argon diffusion mobilized thereby. The low 40Ar/36Ar previously obtained is very likely from the same cause rather than reflecting the isotopic composition of the pre-Cambrian atmosphere. The vitreous character of and the sharp, conchoidal fractures seen in the specimens of type I shungite suggest that the substance may exhibit simple volume diffusion over macroscopic dimensions as glasses do. If so, the diffusion parameters (D infinitely = 3 x 10-4 cm2/s and E = 11 kcal/mole) obtained from the data imply rapid exchange with the atmosphere for any argon initially trapped in centimenter-thick veins of the material. (orig.)

  4. Isotopic fractionation of argon during stepwise release from shungite

    Science.gov (United States)

    Rison, W.

    1980-05-01

    It is noted that in previous attempts to determine the Ar-40/Ar-36 ratio in the ancient atmosphere, the only direct measurement yielding a value below the atmospheric value of today is for argon released at low temperatures from a pre-Cambrian shungite. In the present work, a low value for Ar-40/Ar-36 in gas released from a type I shungite at low temperatures is confirmed. Attention is given to a study of the accompanying Ar-38/Ar-36 ratios and the enhanced ratio of Ar-40/Ar-36 for the fractions released at high temperatures which shows that the effect observed is a result of the stepwise heating and the argon diffusion mobilized thereby. It is suggested that the low Ar-40/Ar-36 obtained in the past is from the same source rather than reflecting the isotropic composition of the pre-Cambrian atmosphere, and that the type I shungite may exhibit simple volume diffusion over macroscopic dimensions as glasses do. It is concluded that if this is so, the diffusion parameters obtained from the data would imply rapid exchange with the atmosphere for any argon initially trapped in the veins of the material.

  5. Bacteria Inactivation Using DBD Plasma Jet in Atmospheric Pressure Argon

    Institute of Scientific and Technical Information of China (English)

    XU Guimin; ZHANG Guanjun; SHI Xingmin; MA Yue; WANG Ning; LI Yuan

    2009-01-01

    A coaxial dielectric barrier discharge plasma jet Was designed,which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply,and an atmospheric pressure glow-like discharge Was achieved.Two kinds of typical bacteria,i.e.,the Staphylococcus aureus(S.aurens)and Escherichia coil(E.coil),were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma.The killing log value (KLV)of S.aureus reached up to 5.38 with a treatment time of 90 s and that of E.coil up to 5.36 with 60 s,respectively.According to the argon emission spectra of the plasma jet and the scanning electron microscope (SEM) images of the two bacteria before and after the plasma treatment.it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation,while the heat,electric field and UV photons had little effect.

  6. Metal clusters on supported argon layers; Metallcluster auf dielektrischen Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Faber, Bernhard

    2011-10-21

    The deposition of small sodium clusters on supported Ar(001)-surfaces is simulated. Theoretical description is achieved by a hierarchical model consisting of time-dependent DFT and molecular dynamics. The valence electrons of the sodium atoms are considered by Kohn-Sham-Scheme with self interaction correction. The interaction of argon atoms and sodium ions is described by atom-atom potentials whereas the coupling to the QM electrons is done by local pseudo-potentials. A decisive part of the model is the dynamical polarizability of the rare-gas atoms. The optional metal support is considered by the method of image charges. The influence of the forces caused by image charges and the influence of the number of argon monolayers on structure, optical response and deposition dynamics of Na{sub 6} and Na{sub 8} is investigated. There is very little influence on cluster structure and only a small shift of the cluster perpendicular to the surface. Concerning optical response the position of the Mie plasmon peak stays robust whereas the details of spectral fragmentation react very sensitively to changes. The forces caused by image charges of the metal support play only a little role with the dynamics of deposition while the thickness of the argon surface strongly influences the dissipation. (orig.)

  7. K-Ar age of young volcanic rocks and excess argon--Binary mixing model and quantitative study of excess argon effect

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A binary mixing model for excess argon is suggested in the note. According to this model and the data of excess argon component obtained in our experiment , a quantitative study of the effect of excess argon on real K-Ar age of young volcanic rocks is done. The result indicates that the effect of 5% excess argon component in samples on K-Ar age of the samples more than 2 Ma is less than 7.36% and can lead K-Ar age of 0.5 Ma samples to increase by 32.4%, while 1% excess argon component leads K-Ar age of 0.5 Ma samples to increase by 6.26%. Therefore, when pre-processed excess argon component is ≤1%, K-Ar age of the samples more than 0.5 Ma should be credible. On this basis we suggest a principal opinion for evaluation of previous K-Ar dating results and propose that the matrix is used to determine K-Ar age of young volcanic rocks. For the samples less than 0.2 Ma, in the case of high excess argon content, even if only 1% excess argon component exists in their matrix, it can also greatly affect their K-A age. Thus it must be careful to treat the dating result.

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

    International Nuclear Information System (INIS)

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

  9. Observing the effect of laser photocoagulation for diabetic retinopathy%糖尿病视网膜病变激光光凝术的疗效观察

    Institute of Scientific and Technical Information of China (English)

    奈蒙

    2013-01-01

    目的 观察糖尿病性视网膜病变(diabetic retinopathy,DR)激光光凝疗效,探讨DR激光光凝术的治疗时机和治疗方式.方法 对79例(114眼)DR患者,根据分期、病情,选择不同方式的光凝治疗,记录患者激光前及激光后1~6个月的最佳视力及眼底血管荧光造影(FFA)情况,评定疗效.结果 79例(114眼)DR患者接受光凝治疗前后视力及FFA结果表明,非增生性DR (nonproliferative diabetic retinopathy,NPDR)患者激光光凝疗效优于增生期DR ( proliferative diabetic retinopathy,PDR)患者.结论 眼底激光是治疗DR有效、安全的方法.严格规范的治疗方式,合理的治疗时机,可保存中心视力,提高疗效,有效治疗糖尿病视网膜病变.

  10. Argon-41 production and evolution at the Oregon State University TRIGA Reactor (OSTR)

    International Nuclear Information System (INIS)

    In this study, argon-41 concentrations were measured at various locations within the reactor facility to assess the accuracy of models used to predict argon-41 evolution from the reactor tank, and to determine the relationship between argon gas evolution from the tank and subsequent argon-41 concentrations throughout the reactor room. In particular, argon-41 was measured directly above the reactor tank with the reactor tank lids closed, at other accessible locations on the reactor top with the tank lids both closed and open, and at several locations on the first floor of the reactor room. These measured concentrations were then compared to values calculated using a modified argon-41 production and evolution model for TRIGA reactor tanks and ventilation values applicable to the OSTR facility. The modified model was based in part on earlier TRIGA models for argon-41 production and release, but added features which improved the agreement between predicted and measured values. The approximate dose equivalent rate due to the presence of argon-41 in reactor room air was calculated for several different locations inside the OSTR facility. These dose rates were determined using the argon-41 concentration measured at each specific location, and were subsequently converted to a predicted quarterly dose equivalent for each location based on the reactor's operating history. The predicted quarterly dose equivalent values were then compared to quarterly doses measured by film badges deployed as dose-integrating area radiation monitors at the locations of interest. The results indicate that the modified production and evolution model is able to predict argon-41 concentrations to within a factor of ten when compared to the measured data. Quarterly dose equivalents calculated from the measured argon-41 concentrations and the reactor's operating history seemed consistent with results obtained from the integrating area radiation monitors. Given the argon-41 concentrations measured

  11. Generation of electron beams from a laser-based advanced accelerator at Shanghai Jiao Tong University

    OpenAIRE

    Elsied, Ahmed M. M.; Hafz, Nasr A. M.; Li, Song; Mirzaie, Mohammad; Sokollik, Thomas; Jie ZHANG

    2014-01-01

    At Shanghai Jiao Tong University, we have established a research laboratory for advanced acceleration research based on high-power lasers and plasma technologies. In a primary experiment based on the laser wakefield acceleration (LWFA) scheme, multi-hundred MeV electron beams having a reasonable quality are generated using 20-40 TW, 30 femtosecond laser pulses interacting independently with helium, neon, nitrogen and argon gas jet targets. The laser-plasma interaction conditions are optimized...

  12. Fabrication and stability of fiber bragg gratings for WDM applications using a 266 nm cw-laser

    DEFF Research Database (Denmark)

    Deyerl, Hans-Jürgen; Sørensen, Henrik Rokkjær; Jensen, Jesper Bo Damm;

    2003-01-01

    Diode pumped continuous wave all solid state UV-lasers operating at 266 nm offer an interesting alternative to frequency doubled argon ion lasers. We compare photosensitivity, UV-writing of Bragg gratings and thermal decay at 244, 257 and 266 nm.......Diode pumped continuous wave all solid state UV-lasers operating at 266 nm offer an interesting alternative to frequency doubled argon ion lasers. We compare photosensitivity, UV-writing of Bragg gratings and thermal decay at 244, 257 and 266 nm....

  13. Laser driven detonation waves above a solid target

    International Nuclear Information System (INIS)

    The interaction of a TEA CO2 laser pulse with a carbon target in an argon atmosphere (p approximately mmHg) is shown to produce a double detonation wave system. The laser driven detonation wave becomes the most important as the gas pressure is increased. Calculation of the energy in the detonation waves is in good agreement with the incident laser energy at different times during the main laser pulse and the long tail. The observation of the incident laser detonation wave accounts for the anomalous energies reported previously. (Auth.)

  14. Past, present, and future of endobronchial laser photoresection.

    Science.gov (United States)

    Khemasuwan, Danai; Mehta, Atul C; Wang, Ko-Pen

    2015-12-01

    Laser photoresection of central airway obstruction is a useful tool for an Interventional Pulmonologist (IP). Endobronchial therapy of the malignant airway obstruction is considered as a palliative measure or a bridge therapy to the definite treatment of cancer. Several ablative therapies such as electrocautery, argon plasma coagulation (APC), cryotherapy and laser photoresection exist in the armamentarium of IP to tackle such presentations. Besides Neodymium-Yttrium, Aluminum, Garnet (Nd:YAG) laser, there are several different types of laser that have been used by the pulmonologist with different coagulative and cutting properties. This chapter focuses on the historical perspective, current status, and potentials of lasers in the management of central airway lesions.

  15. [Characteristics of laser light].

    Science.gov (United States)

    Takac, S; Stojanović, S

    1999-01-01

    laser chamber or optical cavity contains an active lasing medium which usually determines the name of each laser. There are four types of lasing material commonly employed. Solid state lasers use a solid matrix material such as a ruby crystal. Gas lasers use a gas or mixture of gases such as helium, argon, and CO2. Dye lasers employ a complex organic dye in liquid solution or suspension such as rhodamine. Semiconductor lasers use two layers of semiconductor substances such as gallium arsenide. PMID:10352501

  16. Laser Excited Fluorescence For Forensic Diagnostics

    Science.gov (United States)

    McKinney, Robert E.

    1986-07-01

    The application of laser excited fluorescence to the detection and identification of latent fingerprints was first accomplished ten years ago. The development of the technology has progressed rapidly with the introduction of commercial equipment by several manufacturers. Systems based on Argon-ion, Copper-vapor, and frequency-doubled Nd:YAG lasers are compared. The theoretical basis of detection by fluorescence is discussed along with the more useful techniques of dye staining. Other applications of the laser excited fluorescence in forensic investigation include gunshot residue analysis, serology, collection of trace evidence, and document examination.

  17. The effects of argon in the bioenergetics of the hamster and the rat

    Science.gov (United States)

    Tempel, G. E.; Musacchia, X. J.

    1974-01-01

    Oxygen consumption was examined in hamsters and rats exposed to normoxic mixtures of argon at 1 atm. In fasted and nonfasted animals, no marked change in O2 utilization was detectable at 22 C. However, at 7 C a significant decrease in oxygen consumption was observed where the animals were exposed in argon. The data are interpreted in terms of the greater thermal conductivity of nitrogen. The study was prompted by conflicting reports on the metabolic effects of argon and helium.

  18. Percutaneous transluminal laser angioplasty

    International Nuclear Information System (INIS)

    In this paper the authors report on a new technique-percutaneous transluminal laser angioplasty (PLR) which was performed on 9 patients with iliac and/or femoro-popliteal artery occlusion. All patients were males (mean age: 64.5 years) and had arterial occlusion (mean lenght: cm 12.5). PLR was performed with an argon laser (max power: 16 Watts). In 8 out of 9 patients (88.8%) a complete recanalization was obtained of the occluded arterial tract, without complications. In one case only (12.2%) there was an arterial wall perforation with unsatisfactory results. In our opinion, PLR has proven a simple methodology, which can be performed on any patient due to the very low incidence of severe complications and distal embolism. Moreover PLR has quite low costs, and does not prevent eventual surgical/percutaneous interventions

  19. Complex Spectra Structure of an Attosecond Pulse Train Driven by Sub-5-fs Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    YUN Chen-Xia; TENG Hao; ZHANG Wei; WANG Li-Feng; ZHAN Min-Jie; HE Xin-Kui; WANG Bing-Bing; WEI Zhi-Yi

    2011-01-01

    We present the observation of the additional spectral components between the odd order harmonics in the harmonic spectrum generated from argon gas driven by sub-5-fs laser pulses.The theoretical analysis shows that the asymmetric laser field in both spatial and temporal domains leads to this complicated spectrum structure of high order harmonics.

  20. The abundances of neon, sulfur, and argon in planetary nebulae

    Science.gov (United States)

    Beck, S. C.; Lacy, J. H.; Townes, C. H.; Aller, L. H.; Geballe, T. R.; Baas, F.

    1981-01-01

    New infrared observations of Ne II, Ar III, and S IV are used in optical observations of other ionization states of the considered elements to evaluate the abundances of neon, argon, and sulfur in 18 planetary nebulae. Attention is also given to one or more of the infrared lines in 18 other nebulae. It is pointed out that S IV was detected in approximately 90% of the observed objects, while Ar III was found in about 80%, and Ne II in roughly one-third. It is noted that optical observations typically include only a limited region of the nebula, while the infrared measurements frequently involve integration over the entire nebular image.

  1. Ionization coefficients for argon in a micro-discharge

    International Nuclear Information System (INIS)

    Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges. (paper)

  2. Kinetic modeling of the Townsend breakdown in argon

    Science.gov (United States)

    Macheret, S. O.; Shneider, M. N.

    2013-10-01

    Kinetic modeling of the Townsend breakdown in argon was performed in the "forward-back" approximation. The kinetic model was found to adequately describe the left branch of the Paschen curve, and the important role of ionization by fast ions and atoms near the cathode, as well as the increase in secondary emission coefficient in strong electric fields described in the literature, was confirmed. The modeling also showed that the electron energy distribution function develops a beam of high-energy electrons and that the runaway effect, i.e., the monotonic increase of the mean electron energy with the distance from the cathode, occurs at the left branch of the Paschen curve.

  3. Ionization coefficients for argon in a micro-discharge

    Science.gov (United States)

    Kuschel, Thomas; Stefanović, Ilija; Malović, Gordana; Marić, Dragana; Petrović, Zoran Lj

    2013-08-01

    Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges.

  4. Diffusion coefficient of metal vapours into rare gases. Mercury - argon

    International Nuclear Information System (INIS)

    The source information is present as well as the results of analysis and integration of data on mutual diffusion coefficient (MDC) of mercury - argon mixture at Hg concentration → 0 in 300-2500 K temperature range. Reference data on MDC for metal - inert gas binary mixtures obtained on the base of complex analysis of various information, as it exemplified by Hg-Ar pair, can be used as a part of metrological support at calibration of devices for determination MDC of gas - metal vapors

  5. Electron drift velocity in argon-methane mixture

    International Nuclear Information System (INIS)

    Described are the results of a series of measurements of electron drift velocity taken with samples of chemically pure grade gas mixture of Ar-10% CH4 (N2222O<2 ppm). The measured drift velocity is plotted as a function of the ratio of electric field to pressure in the range from 0.05 to 0.8 V/cmxtorr. The measurements are reproducible only to within 4%. The results of numerical calculations employing the well-established argon elastic and methane elastic and inelastic cross sections are also included. The disagreement from the present experimental results, and from those obtained elsewhere, is rather puzzling

  6. Optical fiber read-out for liquid argon scintillation light

    CERN Document Server

    Csáthy, J Janicskó; Kratz, J; Schönert, S; Wiesinger, Ch

    2016-01-01

    In this paper we describe the performance of a light detector for Ar scintillation light made of wavelength-shifting (WLS) fibers connected to Silicon-Photomultipliers (SiPM). The setup was conceived to be used as anti-Compton veto for high purity germanium (HPGe) detectors operated directly in liquid Argon (LAr). Background suppression efficiencies for different radioactive sources were measured in a test cryostat with about 800 kg LAr. This work was part of the R\\&D effort for the GERDA experiment.

  7. Study of a novel electromagnetic liquid argon calorimeter TGT

    International Nuclear Information System (INIS)

    The concept and the basic design of a fast, highly granular and compact electromagnetic liquid argon calorimeter are described. This novel calorimeter offers uniform energy response and constant energy resolution independent of the production angle of an impinging particle and of its impact position at the calorimeter. An example of a calorimeter with full rapidity coverage in an application in a collider detector is given. An important aspect of the concept is the electronics for fast signal processing matched to the short charge collection time. We report on the experience with the realization of a prototype calorimeter module and on its performance in a test beam exposure. 15 refs., 16 figs., 2 tabs

  8. Activation of copper by nitrogen and argon beams

    Energy Technology Data Exchange (ETDEWEB)

    Chetvertkova, Vera [IAP, Goethe-University, Frankfurt am Main (Germany); GSI Darmstadt (Germany); Mustafin, Edil; Strasik, Ivan [GSI Darmstadt (Germany); Belousov, Anton [TU Darmstadt (Germany); Latysheva, Ludmila; Sobolevsky, Nikolai [INR RAS, Moscow (Russian Federation); Ratzinger, Ulrich [IAP, Goethe-University, Frankfurt am Main (Germany)

    2012-07-01

    Monte Carlo transport codes are widely used for various purposes in nuclear physics, radiation protection, medical applications, accelerator design etc. Code verification by experiments is needed to be sure that the codes give accurate results. New data on the activation of copper by a nitrogen beam of 500 MeV/u is presented and compared with FLUKA and SHIELD simulation results. The activation of copper by a nitrogen beam is compared to activation by an argon beam and respective simulations. This gives a chance to see the accuracy of the codes at different projectile masses. Correspondences and discrepancies of calculations and experiments are discussed.

  9. Study of a Novel Concept for a Liquid Argon Calorimeter \

    CERN Multimedia

    2002-01-01

    % RD33 \\\\ \\\\ The development of a fast, highly granular and compact electromagnetic liquid argon calorimeter prototype is proposed as a generic R\\&D project for a novel concept of calorimetry in proton-proton and electron-positron collider detectors: the $^{\\prime$Thin Gap Turbine$^{\\prime}$ (TGT). The TGT calorimeter has a modular construction, is flexible in its longitudinal and transverse granularity, and offers a uniform energy response and resolution, independent of the production angle of incident particles. An important aspect of the project is the development of fast, radiation-hard front-end electronics which is operating in the cold.

  10. Activation of aluminum by argon: Experimental study and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chetvertkova, V., E-mail: v.chetvertkova@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); J. W. Goethe-University Frankfurt am Main, IAP, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Strasik, I. [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); J. W. Goethe-University Frankfurt am Main, IAP, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Belousov, A. [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); Iwase, H. [High Energy Accelerator Research Organization, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Mokhov, N. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Mustafin, E. [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); Latysheva, L. [Institute for Nuclear Research RAS, 117312 Moscow (Russian Federation); Pavlovic, M. [FEI STU, Ilkovicova 3, 812 19 Bratislava (Slovakia); Ratzinger, U. [J. W. Goethe-University Frankfurt am Main, IAP, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Sobolevsky, N. [Institute for Nuclear Research RAS, 117312 Moscow (Russian Federation)

    2011-06-15

    The paper presents the results of irradiation of aluminum targets by 430 and 500 MeV/u argon beams. Gamma-spectra were measured after the end of the irradiation in order to identify the induced nuclides as well as to determine their residual activity depth-profiles. The results of this experiment are compared with Monte Carlo simulations by FLUKA, GEANT4, MARS, PHITS and SHIELD-A codes. In case of a thin target, the agreement between the experiment and simulations is satisfactory, while in case of a thick target, some discrepancies are observed.

  11. Electron transport in argon in crossed electric and magnetic fields

    Science.gov (United States)

    Ness; Makabe

    2000-09-01

    An investigation of electron transport in argon in the presence of crossed electric and magnetic fields is carried out over a wide range of values of electric and magnetic field strengths. Values of mean energy, ionization rate, drift velocity, and diffusion tensor are reported here. Two unexpected phenomena arise; for certain values of electric and magnetic field we find regions where the swarm mean energy decreases with increasing electric fields for a fixed magnetic field and regions where swarm mean energy increases with increasing magnetic field for a fixed electric field. PMID:11088933

  12. Size dependent transition to solid hydrogen and argon clusters probed via spectroscopy of PTCDA embedded in helium nanodroplets

    Science.gov (United States)

    Dvorak, Matthieu; Müller, Markus; Bünermann, Oliver; Stienkemeier, Frank

    2014-04-01

    Complexes made of either ArN or (H2)N clusters (N = 1-170) and a single PTCDA molecule (3,4,9,10-perylene-tetracarboxylic-dianhydride) are assembled inside helium droplets and spectroscopically studied via laser-induced fluorescence spectroscopy. The frequency shift and line-broadening are analyzed as a function of N and of the pick-up order of the PTCDA and cluster material in order to track liquid or solid properties of the clusters. For argon, the solid phase is observed for N > 10 above which the pick-up order dramatically influences the localization of the chromophore with respect to the Ar cluster. If the droplets are doped first with Ar, the chromophore remains on the surface of a solid cluster whereas for the reversed pick-up order the molecule is surrounded by an argon shell. At N < 10 wetting and the formation of the first solvation shell are observed. For para-hydrogen, a transition to the solid is observed at N ˜ 20-25, confirming previous theoretical predictions on the existence of a liquid-like phase at such small sizes, even below the bulk hydrogen freezing temperature.

  13. 激光治疗糖尿病视网膜病变的疗效观察%Laser treatment for diabetic retinopathy

    Institute of Scientific and Technical Information of China (English)

    张未来; 陈蕾

    2008-01-01

    目的 探讨激光治疗糖尿病视网膜病变的效果.方法 根据DRPSG(Diabetic Retinopathy Photocoagulation Study Group)制定的治疗技术规定,对280例365只眼分别为增殖前期糖尿病视网膜病变(Preproliferative diabetic retinopathy,PPDR)、增殖期糖尿病视网膜病变(Proliferative diabetic retinopathy,PDR)及糖尿病性黄斑水肿(Diabetic macular edema,DME)患者,分别行标准全视网膜光凝(S-PRP)、超全视网膜光凝(E-PRP)、局限或格栅光凝.术后3、6、12个月行FFA及彩色眼底像,新生血管未消退者和无灌注区尚存者追加光凝,随访3~36个月.结果 355只眼行全视网膜光凝,新生血管或无灌注区全部或部分消退256只眼,有效率为72.1%:视力不变和增进292只眼,占82.3%;35只黄斑水肿眼局限或格栅光凝后,26只眼水肿减轻或消失,有效率74.3%.结论 激光治疗糖尿病性视网膜病变安全有效.%Objective To evaluate the technique of laser treatment for diabetic retinopathy.Methods According to the treatment technique stipulations formulated by DRPSG (Diabetic Retinopathy photo coagulation Study Group),365 eyes of 280 patients suffering from preprcliferative diabetic retinopathy(PPDR), proliferative diabetic retinopathy (POR) and diabetic macular edema (DME) repectively were treated with laser treatment.These patients received the treatment of standard panretinal photocoagulation(S-PRP) and extra panretinal photocoagulation (E-PRP).Those with macular edema received the focal and grid photocoagulation.The fundus fluorescein angio graphy (FFA)and color photograph were taken 3,6 and12 months after the treatment.For those cases with remaining new vessels and non-perfusion areas, the treatment was complemented with further photocoagulation. The follow-up period was 3~36 months. Results Retinal new vessels partly or entirely regressed in 256 eyes (about 72.1%)of the 355 eyes subjected to PRP. Visual acuity were improved or maintained in 292 eyes

  14. GAVE: An interesting cause of iron deficiency anemia

    Directory of Open Access Journals (Sweden)

    Sham Santhanam

    2015-01-01

    Full Text Available Gastric antral vascular ectasia (GAVE is a rare cause for chronic severe gastrointestinal bleeding requiring repeated transfusions. We present here the case of 55-year-old female who presented with severe iron deficiency anemia with melena. The disease was further diagnosed as GAVE due to the presence of watermelon stomach on endoscopy with features of limited scleroderma. The patient showed symptomatic improvement on treatment with Argon laser photocoagulation and blood transfusion.

  15. 1.06-μm Nd:YAG laser coagulation tonsillectomy: an animal study

    Science.gov (United States)

    Wang, Zhi; Pankratov, Michail M.; Volk, Mark S.; Perrault, Donald F., Jr.; Shapshay, Stanley M.

    1995-05-01

    Tonsillectomy is one of the most frequently performed surgeries which is not free from post- operative morbidity. We have developed a non contact photocoagulation technique using 1.06 micrometers Nd:YAG laser and tested its safety and efficacy in an animal model. Eight animals were divided into the laser coagulation group (6 animals) and the laser excision group (2 animals). Tonsils of the laser coagulation animals were irradiated with 8 - 10 W of laser power for 5 - 6 min in a slow painting-like motion over the surface of a tonsil until slight blanching of mucosa was noticed. Tonsils of the laser excision group were resected with 25 - 30 W of 1.06 micrometers Nd:YAG laser power through a contact fiber. The animals were examined endoscopically at 1.5 hrs and at 2, 5, 12, 30, and 42 days post treatment. Atrophic process was followed until total disappearance of tonsillar tissue was observed. The animals were sacrificed at various time intervals and the tonsillar specimens were collected for gross and histological examination. The thermal damage to mucosa and adjacent tissues was minimal which we attribute to a low laser power and cooling from preoperative injection of saline into subcapsular space. The potential advantages of this technique include intact mucosa with no intra- or post-operative bleeding, less pain, and avoidance of general anesthesia. These advantages may enable this surgery to become an in-the-office procedure.

  16. Laser therapy and sclerotherapy in the treatment of oral and maxillofacial hemangioma and vascular malformations

    Science.gov (United States)

    Crişan, Bogdan; BǎciuÅ£, Mihaela; BǎciuÅ£, Grigore; Crişan, Liana; Bran, Simion; Rotar, Horatiu; Moldovan, Iuliu; Vǎcǎraş, Sergiu; Mitre, Ileana; Barbur, Ioan; Magdaş, Andreea; Dinu, Cristian

    2016-03-01

    Hemangioma and vascular malformations in the field of oral and maxillofacial surgery is a pathology more often found in recent years in patients. The aim of this study was to evaluate the efficacy of the laser photocoagulation performed with a diode laser (Ga-Al-As) 980 nm wavelength in the treatment of vascular lesions which are located on the oral and maxillofacial areas, using color Doppler ultrasonography for evaluation of the results. We also made a comparison between laser therapy and sclerotherapy in order to establish treatment protocols and recommendations associated with this pathology. We conducted a controlled study on a group of 92 patients (38 male and 54 female patients, with an average age of 36 years) having low flow hemangioma and vascular malformations. Patients in this trial received one of the methods of treatment for vascular lesions such as hemangioma and vascular malformations: laser therapy or sclerotherapy. After laser therapy we have achieved a reduction in size of hemangioma and vascular malformations treated with such a procedure, and the aesthetic results were favorable. No reperfusion or recanalization of laser treated vascular lesions was observed after an average follow-up of 6 to 12 months. In case of sclerotherapy a reduction in the size of vascular lesions was also obtained. The 980 nm diode laser has been proved to be an effective tool in the treatment of hemangioma and vascular malformations in oral and maxillofacial area. Laser therapy in the treatment of vascular lesions was more effective than the sclerotherapy procedure.

  17. LArIAT: Liquid Argon In A Testbeam

    CERN Document Server

    Cavanna, F; Raaf, J; Rebel, B

    2014-01-01

    Liquid Argon Time Projection Chambers (LArTPCs) are ideal detectors for precision neutrino physics. These detectors, when located deep underground, can also be used for measurements of proton decay, and astrophysical neutrinos. The technology must be completely developed, up to very large mass scales, and fully mastered to construct and operate these detectors for this physics program. As part of an integrated plan of developing these detectors, accurate measurements in LArTPC of known particle species in the relevant energy ranges are now deemed as necessary. The LArIAT program aims to directly achieve these goals by deploying LArTPC detectors in a dedicated calibration test beam line at Fermilab. The set of measurements envisaged here are significant for both the short-baseline (SBN) and long-baseline (LBN) neutrino oscillation programs in the US, starting with MicroBooNE in the near term and with the adjoint near and far liquid argon detectors in the Booster beam line at Fermilab envisioned in the mid-term...

  18. A liquid argon scintillation veto for the GERDA experiment

    International Nuclear Information System (INIS)

    Gerda is an experiment to search for the neutrinoless double beta decay of 76Ge. Results of Phase I have been published in summer 2013. Currently Gerda is being upgraded to a second phase. To reach the aspired background index of ≤ 10-3 cts/(keV . kg . yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). It has been demonstrated by the LArGe test facility that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. This talk focusses on the light instrumentation which is being installed in GERDA. Photomultiplier tubes (PMT) and wavelength-shifting fibers connected to silicon photomultipliers (SiPM) are combined to maximize the photoelectron-yield with respect to various background sources. Monte Carlo simulations have been performed to optimize the design for background suppression and low self-induced background. First results of the prototypes and the progress of installation are reported.

  19. A liquid argon scintillation veto for the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wegmann, Anne [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2014-07-01

    Gerda is an experiment to search for the neutrinoless double beta decay of {sup 76}Ge. Results of Phase I have been published in summer 2013. Currently Gerda is being upgraded to a second phase. To reach the aspired background index of ≤ 10{sup -3} cts/(keV . kg . yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). It has been demonstrated by the LArGe test facility that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. This talk focusses on the light instrumentation which is being installed in GERDA. Photomultiplier tubes (PMT) and wavelength-shifting fibers connected to silicon photomultipliers (SiPM) are combined to maximize the photoelectron-yield with respect to various background sources. Monte Carlo simulations have been performed to optimize the design for background suppression and low self-induced background. First results of the prototypes and the progress of installation are reported.

  20. Some transport properties in plasmas containing argon and fluorine

    Directory of Open Access Journals (Sweden)

    Novaković R.N.V.

    2003-01-01

    Full Text Available In this paper some results of numerical evaluation of transport coefficients in plasmas in the mixtures of argon and fluorine are presented. These transport characteristics are given in the function of the temperature for low pressures ranging from 0,1 kPa to 1,0 kPa and for low temperatures between 500 K and 5 000 K in argon plasmas with 20% and 30% of the fluorine added. It is assumed that the system is kept under constant pressure and that a corresponding state of local thermodynamical equilibrium (LTE is attained in it. The equilibrium plasma composition, necessary for the evaluations, was determined on the ground of the Saha equations for ionization processes and the law of mass action for the thermal dissociation of F2, combined with the charge conservation relation and the assumption that the pressure remained constant in the course of temperature variations. The ionization energy lowering, required in conjunction with the Saha equations, was obtained with the aid of a modified expression for the plasma Debye radius proposed previously. A previously derived expression for the modified Debye radius, offering the possibility to treat the plasmas considered as weakly non-ideal in the whole temperature range, is used. The cut-off at the Landau length rather than of the smallest of ionic radii is introduced. This alteration in the evaluation procedure brings different considerable changes in the final numerical results for the all relevant quantities.

  1. Compilation of electron collision excitation cross sections for neutro argon

    International Nuclear Information System (INIS)

    The present work presents a compilation and critical analysis of the available data on electron collision excitation cross sections for neutral Argon levels. This study includes: 1.- A detailed description in intermediate coupling for all the levels belonging the 20 configurations 3p''5 ns(n=4 to 12), np(n=4 to 8) and nd(n=3 to 8) of neutral Argon. 2.- Calculation of the electron collision excitation cross sections in Born and Born-Oppenheimer-Ochkur approximations for all the levels in the 14 configurations 3p''5 ns(n=4 to 7), np(n=4 to 7) and nd(n=3 to 8). 3.- Comparison and discussion of the compiled data. These are the experimental and theoretical values available from the literature, and those from this work. 4.- Analysis of the regularities and systematic behaviors in order to determine which values can be considered more reliable. It is show that the concept of one electron cross section results quite useful for this purpose. In some cases it has been possible to obtain in this way approximate analytical expressions interpolating the experimental data. 5.- All the experimental and theoretical values studied are graphically presented and compared. 6.- The last part of the work includes a listing of several general purpose programs for Atomic Physics calculations developed for this work. (Author)

  2. Elastic properties of liquid and solid argon in nanopores.

    Science.gov (United States)

    Schappert, Klaus; Pelster, Rolf

    2013-10-16

    We have measured sorption isotherms and determined the intrinsic longitudinal elastic modulus β(Ar,ads) of nanoconfined material via ultrasonic measurements combined with a special effective medium analysis. In the liquid regime the adsorbate only contributes to the measured effective properties when the pores are completely filled and the modulus is bulklike. At partial fillings its contribution is cancelled out by the high compressibility of the vapour phase. In contrast, at lower temperatures frozen argon as well as underlying liquid surface layers cause a linear increase of the effective longitudinal modulus upon filling. During sorption the contribution of the liquid surface layers near the pore wall β(Ar,surf) increases with the thickness of the solid layers reaching the bulk value β(Ar,liquid) only in the limit of complete pore filling. We interpret this effect as due to the gradual stiffening of the solid argon membrane. The measurements and their analysis show that longitudinal ultrasonic waves are well suited to the study of the elastic properties and liquid-solid phase transitions in porous systems. This method should also help to detect the influence of nanoconfinement on elastic properties in further research. PMID:24057946

  3. Local effects of ECRH on argon transport at ASDEX upgrade

    International Nuclear Information System (INIS)

    Future deuterium-tritium magnetically confined fusion power plants will most probably rely an high-Z Plasma Facing Components (PFCs) such as tungsten. This choice is determined by the necessity of low erosion of the first wall materials (to guarantee a long lifetime of the wall components) and by the need to avoid the too high tritium wall retention of typical carbon based PFCs. The experience gathered at the ASDEX Upgrade (AUG) tokamak has demonstrated the possibility of reliable and high performance plasma operation with a full tungsten-coated first wall. The observed accumulation of tungsten which can lead to excessive radiation losses is mitigated with the use of Electron Cyclotron Resonance Heating (ECRH). Although this impurity control method is routinely performed at AUG, the underlying physics principles are still not clear. This thesis aims an providing further knowledge an the effects of ECRH an the transport of impurities inside the core plasma. The transport of argon has been therefore investigated in-depth in purely ECR heated L-mode (low-confinement) discharges. Studies an impurity transport in centrally ECR heated nitrogen-seeded H-mode (high-confinement) discharges have also been performed. To this scope, a new crystal X-ray spectrometer of the Johann type has been installed an AUG for argon concentration and ion temperature measurements. New methods for the experimental determination of the total argon density through the integrated use of this diagnostic and of the Soft X-Ray (SXR) diode arrays have been developed. This gives the possibility of evaluating the full profiles of the argon transport coefficients from the linear flux-gradient dependency of local argon density. In comparison to classical χ2-minimization methods, the approach proposed here delivers transport coefficients intrinsically independent of the modelling of periodic relaxation mechanisms such as those Lied to sawtooth MHD (Magneto-Hydro-Dynamic) activity. Moreover, the good

  4. Laser treatment of oral vascular malformations

    Science.gov (United States)

    Romeo, U.; Gaimari, G.; Mohsen, M.; Tenore, G.; Palaia, G.

    2014-01-01

    Oral Vascular Malformations (OVM) are congenital anomalies characterized by morph-structural and/or functional changes of nature in severity and extension. OVM can affect any type of vessels arterial, venous or lymphatic and any capillary or anatomical. They are divided into two categories: low and high flow. In this study were treated 40 patients with OVM with a range size from 2 mm to 44 mm; they were subjected to clinical examination supported by Colour-Doppler Ultrasound instrumental examination and only for doubt cases the Magnetic Resonance Imaging (MRI) was prescribed. Only low flow venous and capillary malformations were treated by GaAlAs laser (Wiser®, Lambda, Brindole,Italy, 980nm) and KTP laser (SmartLite®, DEKA, Florence, Italy, 532nm) with two different techniques: the Transmucosal Thermophotocoagulation (TMT) and the Intralesional Photocoagulation (ILP). These techniques permitted a good control of haemostasis, avoiding bleeding both during surgery and in the postoperative. It is obtained an excellent and good healing respectively in 10% and 60% of cases, a moderate and poor resolution respectively in 22.5% and 7.5% of cases. A clear diagnosis allowed the management of Venous malformations (VM) by laser devices with wavelengths highly absorbed in haemoglobin in safety and efficacy and according to the principles of minimal invasive surgery. The aim of this study was to verify if the laser is effective in the treatment of OVM for the purpose of the clinical findings and the postoperative course. The Authors concluded that the laser can be considered the "gold standard" for treating OVM.

  5. Laser-Controlled Growth of Needle-Shaped Organic Nanoaggregates

    DEFF Research Database (Denmark)

    Balzer, Frank; Rubahn, Horst-Günter

    2002-01-01

    Arrays of mutually parallel oriented, single-crystalline, needle-like structures of light-emitting p-hexaphenyl molecules are generated in the focus of an argon ion laser. The cross sectional dimensions of the needles are of the order of 100 to 200 nm with lengths up to several hundred micrometers...

  6. Luminescence from Laser-Created Bubbles in Cryogenic Liquids

    OpenAIRE

    Baghdassarian, Ohan; Tabbert, Bernd; Williams, Gary A.

    1999-01-01

    A luminescence pulse has been observed from a laser-created bubble in liquid nitrogen and liquid argon at the first collapse point of the bubble. An unusual feature is that the width of the pulse is of order 100-1000 ns, much longer than the 2-8 ns pulses observed when the same experiment is carried out with a water sample.

  7. Laser-assisted oral surgery in general practice

    Science.gov (United States)

    McCauley, Mark C.

    1995-04-01

    This presentation will demonstrate and discuss any surgical applications of the Argon dental laser. This presentation will also increase the awareness and basic understanding of the physical principals of the Argon laser. The wavelength of the Argon laser is specifically absorbed by red pigments such a hemoglobin which is abundant in oral soft tissue. The result is a sharp clean incision with minimal thermal damage to adjacent healthy tissue. Preprosthetic procedures such as full arch vestibuloplasty, labial and lingual frenectomy, and epulis fissuratum removal will be demonstrated. Other soft tissue management procedures such as minor periodontal pocket elimination surgery (gingivectomy), removal of hyperplastic granulation tissue from around poorly maintained implants, and the removal of granulation and/or cystic tissue from the apex of teeth undergoing endodontic (apicoec-tomy) surgery will also be demonstrated and discussed. Provided basic oral surgery protocol is followed, surgical procedures utilizing the Argon laser can be accomplished with minimal bleeding, minimal trauma and with minimal post-operative discomfort.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    The water content of the carrier flow originating from an electrothermal vaporization unit (ETV) attached to an inductively coupled plasma mass spectrometer was monitored by following the argon hydride ion (ArH+) at m/z=37. The goal was to measure the water expelled by the ETV at sample vaporization and evaluate the influence of this parameter on the ion-generation efficiency. Linear responses from the argon hydride were obtained when the water loading in the plasma injector flow was increased from 0 to 3.3 mg/min. Other argides and water-derived species (Ar+, Ar+2 and O+2) were also monitored simultaneously and the effects from operating parameters have been calculated for each species. The magnitude of these effects can eventually be used as diagnosis tools. It was also found that signals for zinc, copper, lead, antimony and arsenic were greatly influenced by slight variations in water loading at low water levels. These signal fluctuations are greatly attenuated and transients' shapes restored by convoluting each element transient with the ArH+ or Ar+2 curves that were recorded simultaneously. Envisioned applications that would benefit from a water-enhanced signal include spray electrothermal vaporization, direct sample insertion and laser ablation for inductively coupled plasma-mass spectrometry. The argon dimer Ar+2 seems more appropriate for making the correction since it provides a direct insight on the plasma temperature and provides a robust signal. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Ful distil ation argon producing crud argon column on operating experience%全精馏制氩粗氩塔操作经验浅谈

    Institute of Scientific and Technical Information of China (English)

    马光显

    2015-01-01

    This paper briefly introduces the ful distil ation argon recovery process in the crude argon column in air separation system of cooling,heating and put some matters needing attention in use.%简要介绍了全精馏制氩过程中粗氩塔在空分系统降温、升温及投用中的一些注意事项。

  11. Progress of the Laser-based Experiment OSQAR

    OpenAIRE

    Sulc, Miroslav; Pugnat, Pierre; Ballou, Rafik; Deferne, Guy; Duvillaret, Lionel; Finger Jr., Michael; Finger, Michael; Hošek, Jan; Husek, Thomas; Jost, Rémy; Kral, Miroslav; Kunc, S.; Macuchova, Karolina; Meissner, Krzysztof; Morville, Jérôme

    2013-01-01

    OSQAR experiment at CERN is based on two laser methods for search of axions and scalar particles. The light shining through the wall experiment has been using two LHC dipole magnets with an optical barrier, argon laser, and cooled 2D CCD detector for the measuring of expected regenerated photons. The second method wants to measure the Vacuum Magnetic Birefringence. An optical set-up with electro-optical modulator has been proposed, validated and subsequently improved in collaborating institut...

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

    Science.gov (United States)

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

    2016-02-01

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

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

    Science.gov (United States)

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

    2007-06-01

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

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

    International Nuclear Information System (INIS)

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

  15. First measurement of the ionization yield of nuclear recoils in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, T. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Sangiorgio, Samuele [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Bernstein, A. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Foxe, Michael P. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering; Hagmann, Chris [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Jovanovic, Igor [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering; Kazkaz, K. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Mozin, Vladimir V. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Norman, E. B. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pereverzev, S. V. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Rebassoo, Finn O. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Sorensen, Peter F. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

    2014-05-01

    Liquid phase argon has long been used as a target medium for particle detection via scintillation light. Recently there has been considerable interest in direct detection of both hypothetical darkmatter particles and coherent elastic neutrino nucleus scattering. These as-yet unobserved neutral particle interactions are expected to result in a recoiling argon atom O(keV), generally referred to in the literature as a nuclear recoil. This prompts the question of the available electromagnetic signal in a liquid argon detector. In this Letter we report the first measurement of the ionization yield (Qy), detected electrons per unit energy, resulting from nuclear recoils in liquid argon, measured at 6.7 keV. This is also the lowest energy measurement of nuclear recoils in liquid argon.

  16. Management of Liver Cancer Argon-helium Knife Therapy with Functional Computer Tomography Perfusion Imaging.

    Science.gov (United States)

    Wang, Hongbo; Shu, Shengjie; Li, Jinping; Jiang, Huijie

    2016-02-01

    The objective of this study was to observe the change in blood perfusion of liver cancer following argon-helium knife treatment with functional computer tomography perfusion imaging. Twenty-seven patients with primary liver cancer treated with argon-helium knife and were included in this study. Plain computer tomography (CT) and computer tomography perfusion (CTP) imaging were conducted in all patients before and after treatment. Perfusion parameters including blood flows, blood volume, hepatic artery perfusion fraction, hepatic artery perfusion, and hepatic portal venous perfusion were used for evaluating therapeutic effect. All parameters in liver cancer were significantly decreased after argon-helium knife treatment (p liver tissue, but other parameters kept constant. CT perfusion imaging is able to detect decrease in blood perfusion of liver cancer post-argon-helium knife therapy. Therefore, CTP imaging would play an important role for liver cancer management followed argon-helium knife therapy.

  17. Laser angioplasty for cardiovascular disease

    Science.gov (United States)

    Okada, Masayoshi

    2005-07-01

    Recently, endovascular interventions such as balloon angioplasty, atherectomy and the stenting method, except for conventional surgery have been clinically employed for the patients with atheromatous plaques of the peripheral- and the coronary arteries, because the number of patients with arteriosclerosis is now increasing in the worldwide. Among these procedures, restenoses after endovascular interventions have been remarkably disclosed in 20-40 % of the patients who underwent percutaneous coronary interventions. Thus, there are still some problems in keeping long-term patency by means of endovascular techniques such as balloon angioplasty and atherectomy (1, 2). For reduction of these problems , laser angioplasty using Argon laser was applied experimentally and clinically. Based on excellent experimental studies, laser was employed for 115 patients with stenotic ,or obstructive lesions occluding more thasn 75 % of the peripheral and the coronary arteries angiographycally.

  18. Development of membrane cryostats for large liquid argon neutrino detectors

    CERN Document Server

    Montanari, D; Gendotti, A; Geynisman, M; Hentschel, S; Loew, T; Mladenov, D; Montanari, C; Murphy, S; Nessi, M; Norris, B; Noto, F; Rubbia, A; Sharma, R; Smargianaki, D; Stewart, J; Vignoli, C; Wilson, P; Wu, S

    2015-01-01

    A new collaboration is being formed to develop a multi-kiloton Long-Baseline neutrino experiment that will be located at the Surf Underground Research Facility (SURF) in Lead, SD. In the present design, the detector will be located inside cryostats filled with 68,400 ton of ultrapure liquid argon (less than 100 parts per trillion of oxygen equivalent contamination). To qualify the membrane technology for future very large-scale and underground implementations, a strong prototyping effort is ongoing: several smaller detectors of growing size with associated cryostats and cryogenic systems will be designed and built at Fermilab and CERN. They will take physics data and test different detector elements, filtration systems, design options and installation procedures. In addition, a 35 ton prototype is already operational at Fermilab and will take data with single-phase detector in early 2016. After the prototyping phase, the multi-kton detector will be constructed. After commissioning, it will detect and study ne...

  19. Fluorescence Spectrum of SiO in an Argon Matrix

    Science.gov (United States)

    Scullman, R.; Hormes, J.; Schroeder, W.; Wiggenhauser, H.

    1987-04-01

    Fluorescence from SiO matrix isolated in argon has been investigated in the wavelength region 120-300 nm. Fluorescence emission spectra from the valence states, A1Π, E1Σ+ and G1Π, revealed that nearly all radiation comes from one channel at 305 nm, which was analysed as originating from the b3Π-X1Σ+ transition. Contrary to the A1Π and G1Π states, the E1Σ+ state also decays radiatively, although weakly, through two other channels situated in the vicinity of 305 nm. These two channels were believed to originate from the a3Σ+-X1Σ+ and e3Σ--X1Σ+ transitions.

  20. Electron Neutrino Classification in Liquid Argon Time Projection Chamber Detector

    CERN Document Server

    Płoński, Piotr; Sulej, Robert; Zaremba, Krzysztof

    2015-01-01

    Neutrinos are one of the least known elementary particles. The detection of neutrinos is an extremely difficult task since they are affected only by weak sub-atomic force or gravity. Therefore large detectors are constructed to reveal neutrino's properties. Among them the Liquid Argon Time Projection Chamber (LAr-TPC) detectors provide excellent imaging and particle identification ability for studying neutrinos. The computerized methods for automatic reconstruction and identification of particles are needed to fully exploit the potential of the LAr-TPC technique. Herein, the novel method for electron neutrino classification is presented. The method constructs a feature descriptor from images of observed event. It characterizes the signal distribution propagated from vertex of interest, where the particle interacts with the detector medium. The classifier is learned with a constructed feature descriptor to decide whether the images represent the electron neutrino or cascade produced by photons. The proposed ap...

  1. Large area liquid argon detectors for interrogation systems

    Energy Technology Data Exchange (ETDEWEB)

    Gary, Charles; Kane, Steve; Firestone, Murray I.; Smith, Gregory [Adelphi Technology LLC, Purdue Technology Center, 5225 Exploration Drive, Indianapolis, IN 46241 (United States); Gozani, Tsahi; Brown, Craig; Kwong, John; King, Michael J. [Rapiscan Laboratories, 520 Almanor Avenue, Sunnyvale, CA 94085 (United States); Nikkel, James A.; McKinsey, Dan [Physics Department, Yale University, New Haven, CT 06520 (United States)

    2013-04-19

    Measurements of the efficiency, pulse shape, and energy and time resolution of liquid argon (LAr) detectors are presented. Liquefied noble gas-based (LNbG) detectors have been developed for the detection of dark matter and neutrinoless double-beta decay. However, the same qualities that make LNbG detectors ideal for these applications, namely their size, cost, efficiency, pulse shape discrimination and resolution, make them promising for portal screening and the detection of Special Nuclear Materials (SNM). Two 18-liter prototype detectors were designed, fabricated, and tested, one with pure LAr and the other doped with liquid Xe (LArXe). The LArXe detector presented the better time and energy resolution of 3.3 ns and 20% at 662 KeV, respectively. The total efficiency of the detector was measured to be 35% with 4.5% of the total photons detected in the photopeak.

  2. Argon plasma coagulation for treatment of hemorrhagic radiation gastroduodenitis

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Shu-Ji; Aoyama, Nobuo; Shirasaka, Daisuke; Inoue, Takashi; Kuroda, Kohei; Ebara, Shigeyuki; Tamura, Takao; Miyamoto, Masaki; Kasuga, Masato [Kobe Univ. (Japan). Graduate School of Medicine

    2002-01-01

    A 79-year-old man who had received radiotherapy for portal vein thrombosis due to hepatocellular carcinoma (HCC) 5 months earlier, showed progressive anemia and melena. Endoscopy on admission revealed diffuse bleeding from multiple telangiectasias on the anterior wall of the antrum and bulbus. We treated this patient with a new non-contact hemostatic method: the argon plasma coagulator (APC). The melena stopped after the first session and the hemoglobin level remained stable for 7 months. No delayed complications have been observed. Gastrointestinal bleeding from chronic radiation gastroduodenitis is rarely reported compared with radiation proctitis. This case demonstrates that APC is effective for hemostasis of diffuse bleeding from radiation gastroduodenitis, just as for radiation protitis. (author)

  3. Line ratio diagnostics in helium and helium seeded argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R F [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States); Loch, S D [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States); Ballance, C P [Physics Department, Rollins College, White Park, FL 32789 (United States); Branscomb, D [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States); Pindzola, M S [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States)

    2007-08-15

    We investigate the potential use of line ratio diagnostics to evaluate electron temperature in either helium or helium seeded argon plasmas. Plasmas are produced in a helicon plasma source. A rf compensated Langmuir probe is used to measure both the electron temperature and plasma density while a spectrometer is used to measure He I line intensities from the plasma. For all plasma densities where the electron temperature remains at 5 {+-} 1 eV, three He line ratios are measured. Each experimental ratio is compared with the prediction of three different collisional radiative models. One of these models makes uses of recent R-matrix with pseudo-states calculations for collisional rate coefficients. A discussion related to the different observations and model predictions is presented.

  4. Photodegradation Mechanisms of Tetraphenyl Butadiene Coatings for Liquid Argon Detectors

    CERN Document Server

    Jones, B J P; Conrad, J M; Pla-Dalmau, A

    2013-01-01

    We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry we have detected the ultraviolet-blocking impurity benzophenone (BP). We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. Based on the presence and initially exponential increase in the concentration of benzophenone observed, we propose that TPB degradation is a free radical-mediated photooxidation reaction, which is subsequently confirmed by displaying delayed degradation using a free radical inhibitor. Finally we show that the performance of wavelength-shifting coatings of the type envisioned for the LBNE experiment can be improved by 10-20%, with significantly delayed UV degradation, by using a 20% admixture of 4-tert-Butylcatechol.

  5. Kinetic modeling of the Townsend breakdown in argon

    Energy Technology Data Exchange (ETDEWEB)

    Macheret, S. O.; Shneider, M. N. [Department of Mechanical and Aerospace Engineering, Princeton University, D-414 Engineering Quadrangle, Princeton, New Jersey 08544 (United States)

    2013-10-15

    Kinetic modeling of the Townsend breakdown in argon was performed in the “forward-back” approximation. The kinetic model was found to adequately describe the left branch of the Paschen curve, and the important role of ionization by fast ions and atoms near the cathode, as well as the increase in secondary emission coefficient in strong electric fields described in the literature, was confirmed. The modeling also showed that the electron energy distribution function develops a beam of high-energy electrons and that the runaway effect, i.e., the monotonic increase of the mean electron energy with the distance from the cathode, occurs at the left branch of the Paschen curve.

  6. Uranium (III) precipitation in molten chloride by wet argon sparging

    Science.gov (United States)

    Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

    2016-06-01

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl2 (30-70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10-4.0, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl3 precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO2 powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation.

  7. The readout driver (ROD) for the ATLAS liquid argon calorimeters

    Science.gov (United States)

    Efthymiopoulos, Ilias

    2001-04-01

    The Readout Driver (ROD) for the Liquid Argon calorimeter of the ATLAS detector is described. Each ROD module receives triggered data from 256 calorimeter cells via two fiber-optics 1.28 Gbit/s links with a 100 kHz event rate (25 kbit/event). Its principal function is to determine the precise energy and timing of the signal from discrete samples of the waveform, taken each period of the LHC clock (25 ns). In addition, it checks, histograms, and formats the digital data stream. A demonstrator system, consisting of a motherboard and several daughter-board processing units (PUs) was constructed and is currently used for tests in the lab. The design of this prototype board is presented here. The board offers maximum modularity and allows the development and testing of different PU designs based on today's leading integer and floating point DSPs.

  8. Photodegradation mechanisms of tetraphenyl butadiene coatings for liquid argon detectors

    Science.gov (United States)

    Jones, B. J. P.; VanGemert, J. K.; Conrad, J. M.; Pla-Dalmau, A.

    2013-01-01

    We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry we have detected the ultraviolet-blocking impurity benzophenone. We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. Based on the presence and initially exponential increase in the concentration of benzophenone observed, we propose that TPB degradation is a free radical-mediated photooxidation reaction, which is subsequently confirmed by displaying delayed degradation using a free radical inhibitor. Finally we show that the performance of wavelength-shifting coatings of the type envisioned for the LBNE experiment can be improved by 10-20%, with significantly delayed UV degradation, by using a 20% admixture of 4-tert-Butylcatechol.

  9. Liquid Argon Cryogenic Detector Calibration by Inelastic Scattering of Neutrons

    CERN Document Server

    Polosatkin, Sergey; Dolgov, Alexander

    2014-01-01

    A method for calibration of cryogenic liquid argon detector response to recoils with certain energy -8.2 keV - is proposed. The method utilizes a process of inelastic scattering of monoenergetic neutrons produced by fusion DD neutron generator. Features of kinematics of inelastic scattering cause sufficient (forty times) increase in count rate of useful events relative to traditional scheme exploited elastic scattering with the same recoil energy and compatible energy resolution. The benefits of the proposed scheme of calibration most well implemented with the use of tagged neutron generator as a neutron source that allows to eliminate background originated from casual coincidence of signals on cryogenic detector and additional detector of scattered neutrons.

  10. The liquid argon TPC for the ICARUS experiment

    CERN Document Server

    Arneodo, F

    1997-01-01

    The ICARUS project aims at the realisation of a large liquid argon TPC to be run at the Underground Laboratories of Gran Sasso in Italy. An intense R&D; activity has put on firm grounds this new detector technology and experimentally confirmed its feasibility on a few ton scale. Based on these solid achievements, the collaboration is now confident of being able to build and safely operate a multi-kton detector. The reseach program of the experiment involves the systematic study of a wide spectrum of physical phenomena covering many orders of magnitude in the energy deposited in the detector: from the few MeV of solar neutrino interactions, to the about one GeV of the proton decay and atmospheric neutrinos, up to the higher energies of neutrinos from accelerators.

  11. Response Uniformity of the ATLAS Liquid Argon Electromagnetic Calorimeter

    CERN Document Server

    Aharrouche, M; Di Ciaccio, L; El Kacimi, M; Gaumer, O; Gouanère, M; Goujdami, D; Lafaye, R; Laplace, S; Le Maner, C; Neukermans, L; Perrodo, P; Poggioli, L; Prieur, D; Przysiezniak, H; Sauvage, G; Wingerter-Seez, I; Zitoun, R; Lanni, F; Lü, L; Ma, H; Rajagopalan, S; Takai, H; Belymam, A; Benchekroun, D; Hakimi, M; Hoummada, A; Gao, Y; Stroynowsk, R; Aleksa, M; Carli, T; Fassnacht, P; Gianotti, F; Hervás, L; Lampl, W; Collot, J; Hostachy, J Y; Ledroit-Guillon, F; Malek, F; Martin, P; Viret, S; Leltchouk, M; Parsons, J A; Simion, S; Barreiro, F; Del Peso, J; Labarga, L; Oliver, C; Rodier, S; Barrillon, P; Benchouk, C; Djama, F; Hubaut, F; Monnier, E; Pralavorio, P; Sauvage, D; Serfon, C; Tisserant, S; Tóth, J; Banfi, D; Carminati, L; Cavalli, D; Costa, G; Delmastro, M; Fanti, M; Mandell, L; Mazzanti, M; Tartarelli, F; Kotov, K; Maslennikov, A; Pospelov, G; Tikhonov, Yu; Bourdarios, C; Fayard, L; Fournier, D; Iconomidou-Fayard, L; Kado, M; Parrour, G; Puzo, P; Rousseau, D; Sacco, R; Serin, L; Unal, G; Zerwas, D; Dekhissi, B; Derkaoui, J; EL Kharrim, A; Maaroufi, F; Cleland, W; Lacour, D; Laforge, B; Nikolic-Audit, I; Schwemling, Ph; Ghazlane, H; Cherkaoui El Moursli, R; Idrissi Fakhr-Eddine, A; Boonekamp, M; Kerschen, N; Mansoulié, B; Meyer, P; Schwindlingy, J; Lund-Jensen, B

    2007-01-01

    The construction of the ATLAS electromagnetic liquid argon calorimeter modules is completed and all the modules are assembled and inserted in the cryostats. During the production period four barrel and three endcap modules were exposed to test beams in order to assess their performance, ascertain the production quality and reproducibility, and to scrutinize the complete energy reconstruction chain from the readout and calibration electronics to the signal and energy reconstruction. It was also possible to check the full Monte Carlo simulation of the calorimeter. The analysis of the uniformity, resolution and extraction of constant term is presented. Typical non-uniformities of 0.5% and typical global constant terms of 0.6% are measured for the barrel and end-cap modules.

  12. A Thermodynamic Model for Argon Plasma Kernel Formation

    Directory of Open Access Journals (Sweden)

    James Keck

    2010-11-01

    Full Text Available Plasma kernel formation of argon is studied experimentally and theoretically. The experiments have been performed in a constant volume cylindrical vessel located in a shadowgraph system. The experiments have been done in constant pressure. The energy of plasma is supplied by an ignition system through two electrodes located in the vessel. The experiments have been done with two different spark energies to study the effect of input energy on kernel growth and its properties. A thermodynamic model employing mass and energy balance was developed to predict the experimental data. The agreement between experiments and model prediction is very good. The effect of various parameters such as initial temperature, initial radius of the kernel, and the radiation energy loss have been investigated and it has been concluded that initial condition is very important on formation and expansion of the kernel.

  13. The readout driver (ROD) for the ATLAS liquid argon calorimeters

    CERN Document Server

    Efthymiopoulos, I

    2001-01-01

    The Readout Driver (ROD) for the Liquid Argon calorimeter of the ATLAS detector is described. Each ROD module receives triggered data from 256 calorimeter cells via two fiber-optics 1.28 Gbit/s links with a 100 kHz event rate (25 kbit/event). Its principal function is to determine the precise energy and timing of the signal from discrete samples of the waveform, taken each period of the LHC clock (25 ns). In addition, it checks, histograms, and formats the digital data stream. A demonstrator system, consisting of a motherboard and several daughter-board processing units (PUs) was constructed and is currently used for tests in the lab. The design of this prototype board is presented here. The board offers maximum modularity and allows the development and testing of different PU designs based on today's leading integer and floating point DSPs. (3 refs).

  14. Dynamic resonances and tunnelling in the multiphoton ionization of argon

    International Nuclear Information System (INIS)

    We present results of wavepacket simulations for multiphoton ionization in argon. A single active electron model is applied to estimate the single-electron ionization rates and photoelectron energy distributions for λ = 390 nm light with intensities up to I = 2 x 1014 W cm-2. The multiphoton ionization rates are compared with R-matrix Floquet calculations and found to be in very good agreement. The photoelectron energy distribution is used to study the nature of ionization at the higher intensities. Our results are consistent with recent calculations and experiments which show the imprint of the tunnelling process in the multiphoton regime. For few-cycle intense pulses, we find that the strong modulation of intensity and increased bandwidth leads to dynamic mixing of the 3d and 5s resonances.

  15. The ATLAS liquid Argon calorimeters read-out system

    CERN Document Server

    Blondel, A; Fayard, L; La Marra, D; Léger, A; Matricon, P; Perrot, G; Poggioli, L; Prast, J; Riu, I; Simion, S

    2004-01-01

    The calorimetry of the ATLAS experiment takes advantage of different detectors based on the liquid Argon (LAr) technology. Signals from the LAr calorimeters are processed by various stages before being delivered to the Data Acquisition system. The calorimeter cell signals are received by the front-end boards, which digitize a predetermined number of samples of the bipolar waveform and sends them to the Read-Out Driver (ROD) boards. The ROD board receives triggered data from 1028 calorimeter cells, and determines the precise energy and timing of the signals by processing the discrete samplings of the pulse. In addition, it formats the digital stream for the following elements of the DAQ chain, and performs monitoring. The architecture and functionality of the ATLAS LAr ROD board are discussed, along with the final design of the Processing Unit boards housing the Digital Signal Processors (DSP). (9 refs).

  16. Atmospheric dispersion of argon-41 from anuclear research reactor: measurement and modeling of plume geometry and gamma radiation field

    DEFF Research Database (Denmark)

    Lauritzen, Bent; Astrup, Poul; Drews, Martin;

    2003-01-01

    An atmospheric dispersion experiment was conducted using a visible tracer along with the routine release of argon-41 from the BR1 research reactor in Mol, Belgium. Simultaneous measurements of plume geometry and radiation fields for argon-41 decay were performed as well as measurements of the argon...

  17. Photodynamic Therapy for Superficial Esophageal Cancer Using an Excimer Dye Laser

    OpenAIRE

    Seishiro Mimura; Toru Otani; Shigeru Okuda

    1994-01-01

    In order to improve the therapeutic effectiveness of photodynamic therapy with Photofrin II and laser light for superficial esophageal cancer, we employed an excimer dye laser instead of an argon dye laser. Eight superficial esophageal cancer lesions (7 cases) were treated. Of these 8 lesions, 6 were cured by initial treatment, while one lesion required another treatment. The final rate of cure was 88% (7/8).

  18. Diode laser gas nitriding of Ti6Al4V alloy

    OpenAIRE

    A. Lisiecki; A. Klimpel

    2008-01-01

    Purpose: To produce erosion wear resistant and high hardness surface layers of turbofan engine blades and steamturbine blades made of titanium alloy Ti6Al4V laser gas nitrating (LGN) technology of laser alloying was selectedto produce titanium nitrides participations in the titanium alloy matrix surface layers.Design/methodology/approach: Studies on influence of the parameters of laser gas nitriding of titaniumalloy and partial pressure of nitrogen and argon in the gas mixture on the surface ...

  19. Laser Therapy

    Science.gov (United States)

    ... How to Choose the Best Skin Care Products Laser Resurfacing Uses for Laser Resurfacing Learn more about specific conditions where laser ... skin Scars Sun-damaged skin Wrinkles What is laser resurfacing? Laser resurfacing is a procedure that uses ...

  20. Optimization of an Image-Guided Laser-Induced Choroidal Neovascularization Model in Mice.

    Directory of Open Access Journals (Sweden)

    Yan Gong

    Full Text Available The mouse model of laser-induced choroidal neovascularization (CNV has been used in studies of the exudative form of age-related macular degeneration using both the conventional slit lamp and a new image-guided laser system. A standardized protocol is needed for consistent results using this model, which has been lacking. We optimized details of laser-induced CNV using the image-guided laser photocoagulation system. Four lesions with similar size were consistently applied per eye at approximately double the disc diameter away from the optic nerve, using different laser power levels, and mice of various ages and genders. After 7 days, the mice were sacrificed and retinal pigment epithelium/choroid/sclera was flat-mounted, stained with Isolectin B4, and imaged. Quantification of the area of the laser-induced lesions was performed using an established and constant threshold. Exclusion criteria are described that were necessary for reliable data analysis of the laser-induced CNV lesions. The CNV lesion area was proportional to the laser power levels. Mice at 12-16 weeks of age developed more severe CNV than those at 6-8 weeks of age, and the gender difference was only significant in mice at 12-16 weeks of age, but not in those at 6-8 weeks of age. Dietary intake of omega-3 long-chain polyunsaturated fatty acid reduced laser-induced CNV in mice. Taken together, laser-induced CNV lesions can be easily and consistently applied using the image-guided laser platform. Mice at 6-8 weeks of age are ideal for the laser-induced CNV model.

  1. Argon Kα measurement on DIII endash D by Ross filters technique (abstract)

    International Nuclear Information System (INIS)

    Techniques to reduce the heat flux to the divertor plates in tokamak power plants and the consequent erosion of, and subsequent damage to the divertor target plates include the injection of impurities such as argon, that can dissipate the energy (through radiative or collisional processes) before it reaches the target plates. An important issue with this type of scheme is poisoning of the plasma core by the impurities introduced in the divertor region. Subsequently, there is a desire to measure the profiles of the injected impurities in the core. X-ray Ross filters with an effective narrow band pass centered on the argon Kα line at 3.2 keV, have been installed on two of the existing x-ray arrays on DIII endash D in order to help determine the argon concentration profiles. Emissivity profiles of the Kα lines and the emissivity profiles for the argon enhanced continuum can be inferred from the inverted filtered x-ray brightness signals if Te, ne, and Ar18+ profiles are known. The MIST code is used to couple the filtered x-ray signals to the time dependent measurements of Te and ne. Further, the Ar16+ profiles measured by charge transfer spectroscopy, are used as a constraint on the MIST code runs to calculate Ar18+ profiles and unfold the argon emissivity profiles. A discussion of the Ross filters, the DIII endash D argon data, and the data analysis scheme for inferring argon emissivity profiles will be discussed. Estimates of the total argon concentration in the core determined from this technique in DIII endash D argon puff experiments will be presented. copyright 1999 American Institute of Physics

  2. Applications and mechanisms of laser tissue welding in 1995: review

    Science.gov (United States)

    Godlewski, Guilhem; Prudhomme, Michel; Tang, Jing

    1996-01-01

    For several years laser tissue welding has appeared as a new alternative technique for tissue repair instead of manual sutures. It has been evaluated in different experimental models including blood vessels, skin, nerve, intestine, bile ducts, vas and fallopian tube. Different types of lasers with different sets of parameters have been used: carbon dioxide laser, Nd:YAG laser, argon and KTP laser and diode laser. Recent trends in tissue fusion promote near infrared lasers at low irradiance with intraoperative enhancement of light absorption by specific chromophores. As far as microvascular reconstruction is concerned, successful clinical applications are currently published. Although the molecular mechanism involved in welding is not completely understood, the tissular fusion is considered as a thermal phenomena. In laser assisted microvascular anastomosis, the best experimental model, the ultrastructural examination of arteries anastomosed with Nd:YAG, argon or diode laser revealed interdigitation of collagen fibers which appeared swollen, with modified striation and organized in irregular network. The mechanism of welding involving the formation of non covalent bands between collagen strands, is generally induced by a temperature of 60 - 63 degrees Celsius well adapted to collagen denaturation.

  3. Wetting and evaporation of argon nanodroplets on smooth and rough substrates: Molecular dynamics simulations

    Science.gov (United States)

    Li, Qun; Wang, Baohe; Chen, Yonggang; Zhao, Zongchang

    2016-10-01

    Wetting and evaporation behaviors of argon nanodroplets on smooth and rough substrates are studied using molecular dynamics simulations. Effects of interaction energy between solid and argon atoms on wetting and evaporation and differences between nanodroplets on smooth and rough substrates have been investigated. The results show that for both smooth and rough substrates, as the interaction energy between solid and argon atoms increases, the contact angle and total evaporation increase. For rough substrates, the variations of contact angle and contact radius during evaporation progress are much more complex and the total evaporation is much larger than that of smooth substrates.

  4. A Study of Dielectric Breakdown Along Insulators Surrounding Conductors in Liquid Argon

    CERN Document Server

    Lockwitz, Sarah

    2015-01-01

    High voltage breakdown in liquid argon is an important consideration in the design of liquid argon time projection chambers, which are often used as neutrino and dark matter detectors. We have made systematic measurements of breakdown voltages in liquid argon along insulators surrounding negative rod electrodes. The purpose of these tests is to understand the effects of materials, of breakdown path length, and of surface topology. We have found no material-specific effects other than those due to their permittivity. We have found no dependence on breakdown voltage on the length of the exposed insulator. A model for the breakdown mechanism is presented that can help inform future designs.

  5. Design Principles and Operational Results of the Cryogenic System for the ATLAS Liquid Argon Calorimeter

    CERN Document Server

    Fabre, C; Chalifour, M; Gonidec, G; Passardi, Giorgio; Petit, P; Pezzetti, M; Wicek, F

    2009-01-01

    The ATLAS liquid argon calorimeter housed in three independent cryostats containing a total argon volume of about 78 m3 has been installed in the underground cavern. The three detectors have been cooled down following stringent temperature gradient limits and have been filled with liquid argon. The cryostats are now in a stable condition for periods going up to almost two years. The temperature uniformity within each of the three detector volumes is found to be within 70 mK rms, while the temperature stability stays below 5 mK rms.

  6. A new ozone standard - The vapor pressure of ozone at liquid argon temperatures

    Science.gov (United States)

    Mauersberger, K.; Hanson, D.; Morton, J.

    1985-01-01

    The vapor pressure of ozone has been measured at liquid argon temperatures. At the normal boiling point of argon (-185.9 C) an ozone pressure of 0.0405 torr was obtained with an accuracy of + or - 1.5 percent. Increases and decreases in liquid argon temperatures raised and lowered the ozone vapor pressure, respectively. During the vapor pressure measurements the purity of ozone was monitored with a mass spectrometer. The proposed ozone standard will considerably improve the calibration of experiments for atmospheric research, the determination of absorption cross sections and other laboratory ozone studies.

  7. Surface compositional changes in GaAs subjected to argon plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Surdu-Bob, C.C.; Sullivan, J.L.; Saied, S.O.; Layberry, R.; Aflori, M

    2002-12-30

    X-ray photoelectron spectroscopy (XPS) has been employed to study surface compositional changes in GaAs (1 0 0) subjected to argon plasma treatment. The experimental results have been explained in terms of predicted argon ion energies, measured ion densities and etch rates. A model is proposed for the processes taking place at the surface of GaAs in terms of segregation, sputtering and surface relaxation. Stopping and range of ions in matter (SRIM) code has also been employedan aid to identification of the mechanisms responsible for the compositional changes. Argon plasma treatment induced surface oxidation at very low energies and sputtering and surface damage with increasing energy.

  8. Changes in a surface of polycrystalline aluminum upon bombardment with argon ions

    Science.gov (United States)

    Ashkhotov, O. G.; Ashkhotova, I. B.; Bliev, A. P.; Magkoev, T. T.; Krymshokalova, D. A.

    2014-10-01

    The interaction between argon ions and a natural oxide layer of polycrystalline aluminum is studied via Auger electron (AE) and electron energy loss (EEL) spectroscopy. It is found that bombardment with argon ions whose energy is lower than the Al2O3 sputtering threshold results in the accumulation of bombarding ions in interstitial surface voids, thus forming a supersaturated solid solution of target atoms and bombarding ions of argon and nitrogen entrapped by the ion beam from the residual gas of the working chamber of the spectrometer.

  9. In vivo quantification of microglia dynamics with a scanning laser ophthalmoscope in a mouse model of focal laser injury

    Science.gov (United States)

    Alt, Clemens; Lin, Charles P.

    2012-03-01

    Microglia are the resident immune cells of the central nervous system and play a crucial role in maintaining neuronal health and function. Their dynamic behavior, that is, the constant extension and retraction of microglia processes, is thought to be critical for communication between microglia and their cellular neighbors, such as neurons, astrocytes and vascular endothelial cells. Here, we investigated the morphology and dynamics of retinal microglia in vivo under normal conditions and in response to focal laser injury of blood vessel endothelial wall, using a scanning laser ophthalmoscope (SLO) designed specifically for imaging the retina of live mice. The multichannel confocal imaging system allows retinal microstructure, such as the processes of microglia and retinal vasculature, to be visualized simultaneously. In order to generate focal laser injury, a photocoagulator based on a continuous wave (cw) laser was coupled into the SLO. An acousto-optic modulator chopped pulses from the cw laser. A tip-tilt-scanner was used to direct the laser beam into a blood vessel of interest under SLO image guidance. Mild coagulation was produced using millisecond-long pulses. Microglia react dynamically to focal laser injury of blood vessel endothelial walls. Under normal conditions, microglia somas remain stationary and the processes probe a territory of their immediate environment. In response to local injury, process movement velocity approximately doubles within minutes after injury. Moreover, the previously unpolarized process movement assumes a distinct directionality towards the injury site, indicating signaling between the injured tissue and the microglia. In vivo retinal imaging is a powerful tool for understanding the dynamic behavior of retinal cells.

  10. Intraocular applications of the Ho:YAG laser

    Science.gov (United States)

    Boiko, Ernest V.; Danilichev, Vladimir F.; Shishkin, Michael M.; Berezin, Yuri D.; Smirnov, Nicolay N.; Lazo, Victor V.

    1995-05-01

    Despite advances in mechanical vitrectomy, cutting dense membranes and fibrovascular strands remains a technical challenge. Widespread acceptance of carbon dioxide and Er:YAG lasers, which cutting potential and coagulative properties were highly evaluated by experimentators, now is limited because of insufficiently convenient fiberoptic delivery systems. We investigated the use of Ho:YAG laser emitting at 2.09 micrometers to cut experimental vitreous membranes in rabbits. Radiation at 2.09 micrometers is enough strongly absorbed by water (absorption length 385 micrometers ) and can be transmitted through silica fiberoptic delivery system practically without attenuation. At first, the dependence of retinal damage thresholds and wet field thermal effects from distance `endolaser tip--target', energy, pulse rates and number of pulses were determined. With the help of multiple regression analysis models of these processes were constructed. Coagulative and cutting properties of holmium endolaser were assessed on the created transvitreal membranes. Optimal parameters for cutting and coagulation were determined. Based on own experimental studies we also used Ho:YAG endolaser in vitrectomies for diabetes and traumas. The advantages and disadvantages of the 2.09 micrometers infrared wavelength of holmium laser photoincision and photocoagulation in vitreous are discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-01

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

  12. Comparison of different lasers in terms of thrombogenicity of the laser-treated vascular wall.

    Science.gov (United States)

    Ragimov, S E; Belyaev, A A; Vertepa, I A; Dolgov, V V; Furzikov, N P; Akchurin, R S; Repin, V S; Trubetskoy, A V

    1988-01-01

    The thrombogenic properties of the laser-treated vascular wall are reported as quantitatively assessed on the basis of 33 experiments with peripheral canine vessel segments. Three types of surfaces, namely, 1) intact, 2) mechanically de-endothelized, and 3) postlaser, have been simultaneously exposed to platelet-enriched plasma in a sequentially organized artificial circulation system. Then the adherent platelets have been counted on the treated surfaces, and the relative thrombogenicity index has been calculated according to the equation T = (A1 - Aint)/(Ad - Aint), where Aint, Ad, A1 = the adherent platelet counts on intact, mechanically de-endothelized, and laser-treated surfaces, respectively. The following lasers have been evaluated: 1) Nd-YAG, 1,060 nm, continuous wave, 4W; 2) argon-ion, 480 and 514 nm and argon-ion, 350 nm, continuous-wave, 1 W and 400 mW [corrected], respectively; 3) excimer XeCl, 308 nm, pulsed, 30 mJ per pulse, repetition rate 10 Hz [corrected]; and also 4) the laser-heated metal probe (2 mm diameter, Trimedyne, Nd-YAG) 1,060 nm, 8 W. The thrombogenicity index values obtained were 83 +/- 7, 72 +/- 8, 57 +/- 9, 63 +/- 7, and 82 +/- 9%, respectively. The differences between these values were statistically insignificant. The data are suggestive of the essential requirement of, at least, anticoagulant therapy after laser angioplasty irrespective of the laser type.

  13. Laser Thomson Scattering, Raman Scattering and laser-absorption diagnostics of high pressure microdischarges

    International Nuclear Information System (INIS)

    Laser scattering experiments were performed in high pressure (100s of Torr) parallel-plate, slot-type DC microdischarges operating in argon or nitrogen. Laser Thomson Scattering (LTS) and Rotational Raman Scattering were employed in a novel, backscattering, confocal configuration. LTS allows direct and simultaneous measurement of both electron density (ne) and electron temperature (Te). For 50 mA current and over the pressure range of 300 - 700 Torr, LTS yielded Te = 0.9 ± 0.3 eV and ne = (6 ± 3)·1013 cm-3, in reasonable agreement with the predictions of a mathematical model. Rotational Raman spectroscopy (RRS) was employed for absolute calibration of the LTS signal. RRS was also applied to measure the 3D gas temperature (Tg) in nitrogen DC microdischarges. In addition, diode laser absorption spectroscopy was employed to measure the density of argon metastables (1s5 in Paschen notations) in argon microdischarges. The gas temperature, extracted from the width of the absorption profile, was compared with Tg values obtained by optical emission spectroscopy.

  14. Laser Thomson Scattering, Raman Scattering and laser-absorption diagnostics of high pressure microdischarges

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, Vincent M; Belostotskiy, Sergey G; Economou, Demetre J [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204 (United States); Sadeghi, Nader, E-mail: vmdonnelly@uh.ed [Laboratoire de Spectrometrie Physique (UMR C5588), Universite J. Fourier de Grenoble, B P 87, F-38402 Saint-Martin d' Heres Cedex (France)

    2010-05-01

    Laser scattering experiments were performed in high pressure (100s of Torr) parallel-plate, slot-type DC microdischarges operating in argon or nitrogen. Laser Thomson Scattering (LTS) and Rotational Raman Scattering were employed in a novel, backscattering, confocal configuration. LTS allows direct and simultaneous measurement of both electron density (n{sub e}) and electron temperature (T{sub e}). For 50 mA current and over the pressure range of 300 - 700 Torr, LTS yielded T{sub e} = 0.9 {+-} 0.3 eV and n{sub e} = (6 {+-} 3){center_dot}10{sup 13} cm{sup -3}, in reasonable agreement with the predictions of a mathematical model. Rotational Raman spectroscopy (RRS) was employed for absolute calibration of the LTS signal. RRS was also applied to measure the 3D gas temperature (T{sub g}) in nitrogen DC microdischarges. In addition, diode laser absorption spectroscopy was employed to measure the density of argon metastables (1s5 in Paschen notations) in argon microdischarges. The gas temperature, extracted from the width of the absorption profile, was compared with T{sub g} values obtained by optical emission spectroscopy.

  15. Self-assembled heterogeneous argon/neon core-shell clusters studied by photoelectron spectroscopy.

    Science.gov (United States)

    Lundwall, M; Pokapanich, W; Bergersen, H; Lindblad, A; Rander, T; Ohrwall, G; Tchaplyguine, M; Barth, S; Hergenhahn, U; Svensson, S; Björneholm, O

    2007-06-01

    Clusters formed by a coexpansion process of argon and neon have been studied using synchrotron radiation. Electrons from interatomic Coulombic decay as well as ultraviolet and x-ray photoelectron spectroscopy were used to determine the heterogeneous nature of the clusters and the cluster structure. Binary clusters of argon and neon produced by coexpansion are shown to exhibit a core-shell structure placing argon in the core and neon in the outer shells. Furthermore, the authors show that 2 ML of neon on the argon core is sufficient for neon valence band formation resembling the neon solid. For 1 ML of neon the authors observe a bandwidth narrowing to about half of the bulk value.

  16. Surface Chemistry of Polymers Physical Adsorption of Nitrogen, Argon, Sulfur Dioxide and Neopentane on Polyvinylidene Fluoride

    OpenAIRE

    Houriet, Jean-Philippe; Ghiste, Patrick; Stoeckli, Fritz

    2007-01-01

    The adsorption of nitrogen, argon, sulfur dioxide and neopentane on polyvinylidene fluoride has been measured by static methods and by gas-solid chromatography. The polymer has a homogeneous surface of low energy, which is not significantly affected by heating.

  17. Surface modification of polypropylene using argon plasma: Statistical optimization of the process variables

    International Nuclear Information System (INIS)

    Low pressure plasma treatment using radiofrequency (rf) discharge of argon gas was employed to improve the hydrophilicity of polypropylene. The effects of argon plasma on the wettability, surface chemistry and surface morphology of polypropylene were studied using static contact angle measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Increase in surface energy of polypropylene was observed as a result of argon plasma treatment. SEM and AFM images revealed the increased surface roughness. A set of identified process variables (rf power, pressure, argon flow rate and time) were used in this study and were optimized using central composite design (CCD) of response surface methodology (RSM). A statistical model was developed to represent the surface energy in terms of the process variables mentioned above. Accuracy of the model was verified and found to be high.

  18. Simulations of argon accident scenarios in the ATLAS experimental cavern a safety analysis

    CERN Document Server

    Balda, F

    2002-01-01

    Some characteristic accidents in the ATLAS experimental cavern (UX15) are simulated by means of STAR-CD, a code using the "Finite-Volume" method. These accidents involve different liquid argon leaks from the barrel cryostat of the detector, thus causing the dispersion of the argon into the Muon Chamber region and the evaporation of the liquid. The subsequent temperature gradients and distribution of argon concentrations, as well as their evolution in time are simulated and discussed, with the purpose of analysing the dangers related to asphyxiation and to contact with cryogenic fluids for the working personnel. A summary of the theory that stands behind the code is also given. In order to validate the models, an experimental test on a liquid argon spill performed earlier is simulated, showing that the program is able to output reliable results. At the end, some safety-related recommendations are listed.

  19. Pose Measurement Performance of the Argon Relative Navigation Sensor Suite in Simulated Flight Conditions

    Science.gov (United States)

    Galante, Joseph M.; Eepoel, John Van; Strube, Matt; Gill, Nat; Gonzalez, Marcelo; Hyslop, Andrew; Patrick, Bryan

    2012-01-01

    Argon is a flight-ready sensor suite with two visual cameras, a flash LIDAR, an on- board flight computer, and associated electronics. Argon was designed to provide sensing capabilities for relative navigation during proximity, rendezvous, and docking operations between spacecraft. A rigorous ground test campaign assessed the performance capability of the Argon navigation suite to measure the relative pose of high-fidelity satellite mock-ups during a variety of simulated rendezvous and proximity maneuvers facilitated by robot manipulators in a variety of lighting conditions representative of the orbital environment. A brief description of the Argon suite and test setup are given as well as an analysis of the performance of the system in simulated proximity and rendezvous operations.

  20. Formation and characterization of magnesium bisozonide and carbonyl complexes in solid argon.

    Science.gov (United States)

    Wang, Guanjun; Gong, Yu; Zhang, Qingqing; Zhou, Mingfei

    2010-10-14

    The reactions of magnesium atoms with dioxygen and dioxygen/carbon monoxide mixture have been investigated by matrix isolation infrared absorption spectroscopy. Magnesium atoms react with dioxygen in solid argon to form the inserted MgO(2) molecules under UV excitation, which were previously characterized. Annealing allows the dioxygen molecules to diffuse and to react with MgO(2) and form the magnesium bisozonide complex, Mg(O(3))(2), which is proposed to be coordinated by two argon atoms in solid argon matrix. The Mg(O(3))(2)(Ar)(2) complex is characterized to have two equivalent side-on bonded ozonide ligands with a D(2h) symmetry. The coordinated argon atoms can be replaced by carbon monoxide to give the magnesium bisozonide dicarbonyl complex, Mg(O(3))(2)(CO)(2), a neutral magnesium carbonyl complex with CO binding to the Mg(2+) center. PMID:20857987

  1. Photodynamic Therapy With YAG-OPO Laser for Early Stage Lung Cancer

    OpenAIRE

    Harubumi Kato; Tetsuya Okunaka; Chimori Konaka; Kiyoyuki Furuse; Yoko Kusunoki; Takeshi Horai; Nobuhide Takifuji; Syunichi Negoro; Masahiro Fukuoka; Takashi Yaya; Ichiro Kawase

    1997-01-01

    Photodynamic therapy (PDT) utilizing Photofrin is proving to be effective for the treatment of early stage lung cancers. The effect of PDT utilizing YAG-OPO laser as new light source was evaluated in 26 patients (29 lesions) with early stage lung cancers. YAG-OPO laser is solid state tunable laser which is easy to change wavelength between 620 and 670 nm exciting various kinds of photosensitizers. Moreover, YAG-OPO laser is more reliable, smaller and has less consumables than argon-dye laser ...

  2. Dynamic range compression in a liquid argon calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Cleland, W.E. [Univ. of Pittsburgh, PA (United States); Lissauer, D.; Radeka, V.; Rescia, S.; Takai, H. [Brookhaven National Lab., Upton, NY (United States); Wingerter-Seez, I. [LAPP, Annecy-le-Vieux (France)

    1996-12-31

    The anticipated range of particle energies at the LHC, coupled with the need for precision, low noise calorimetry makes severe demands on the dynamic range of the calorimeter readout. A common approach to this problem is to use shapers with two or more gain scales. In this paper, the authors describe their experience with a new approach in which a preamplifier with dynamic gain compression is used. An unavoidable consequence of dynamic gain adjustment is that the peaking time of the shaper output signal becomes amplitude dependent. The authors have carried out a test of such a readout system in the RD3 calorimeter, a liquid argon device with accordion geometry. The calibration system is used to determine both the gain of the individual channels as well as to map the shape of the waveform as a function of signal amplitude. A new procedure for waveform analysis, in which the fitted parameters describe the impulse response of the system, permits a straightforward translation of the calibration waveform to the waveform generated by a particle crossing the ionization gap. They find that the linearity and resolution of the calorimeter is equivalent to that obtained with linear preamplifiers, up to an energy of 200 GeV.

  3. Coherent set of electron cross sections for argon

    Science.gov (United States)

    Alves, L. L.; Ferreira, C. M.

    2011-10-01

    This paper presents a coherent set of electron impact cross sections for argon (elastic momentum-transfer, inelastic for the excitation of 37 levels Ar(4s,4p,3d,5p,4d,6s) and ionization), which was recently uploaded onto the LXcat IST-Lisbon database. The cross section set was validated by comparing calculated swarm parameters (electron mobility and characteristic energy) and rate coefficients (Townsend ionization coefficient and direct + cascade excitation coefficients to the 4s and 4p states) with available experimental data, for E / N = 10-4 - 100 Td and Tg = 300, 77 K. The validation procedure involves the solution to the homogeneous two-term electron Boltzmann equation, resorting to three different solvers: (i) IST-Lisbon's (ii) BOLSIG+ (v1.2) with LXcat; (iii) BOLSIG+ (v1.23). The results obtained with these solvers are compared to evidence the importance of certain numerical features related with both the energy-grid (number of points, grid-type and maximum energy value) and the interpolation scheme adopted for the cross sections. In particular, the latter can cause a 6% variation on the values of swarm parameters at intermediate E/Ns.

  4. An update of argon inelastic cross sections for plasma discharges

    International Nuclear Information System (INIS)

    This paper proposes a coherent set of electron impact inelastic cross sections for argon, based on recent experimental measurements. The updated set is validated by comparing calculated swarm parameters and rate coefficients (obtained by solving the two-term approximation electron Boltzmann equation) with available experimental data. This validation procedure is usually adopted when the cross section set is to be later used in plasma discharge modelling. Simulation results for the electron drift velocity and characteristic energy are in very good agreement with experimental values of these quantities. Calculations, using cross section sets proposed by different authors, of the total (direct + cascade) excitation coefficients to the 4s and 4p states, and of the Townsend ionization coefficient, show that the present set ensures the best overall agreement with measured values. The agreement is particularly good for the excitation coefficient to metastable 4s'[1/2]0 and the Townsend ionization coefficient, which are probably the most relevant electron macroscopic coefficients in the modelling of discharge plasmas

  5. Argon defect complexes in low energy Ar irradiated molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    van Veen, A.; Buters, W.T.M.; van der Kolk, G.J.; Caspers, L.M. (Interuniversitair Reactor Instituut, Delft (Netherlands)); Armstrong, T.R. (Victoria Univ., Wellington (New Zealand). Dept. of Physics)

    1982-03-15

    Thermal desorption spectrometry has been used to study the defects created in Mo irradiated along the <110> direction with Ar ions ranging in energy from 0.1 to 2 keV. In addition to monitoring the release of the implanted Ar, additional information has been obtained by decoration of the defects with low energy helium and subsequent monitoring of the helium release. The studies show evidence that the Ar can be trapped in both substitutional sites and in a configuration in which the Ar is associated with vacancies (ArVsub(n), n >= 2). Most of the Ar implanted at high energy is released at approx. equal to 1500 K by thermal vacancy assisted diffusion. Argon trapped closer to the surface is released at lower temperatures via at least three different surface related release mechanisms. Additional results are presented on the interaction of self interstitial atoms (introduced by 100 eV Xe bombardment) with the Ar defects. Substitutional Ar is found to convert to interstitial Ar which seems to be mobile at room temperature. The Ar-vacancy complexes are found to be reduced to substitutional Ar. The results of atomistic calculations of the release mechanisms will also be presented.

  6. Scintillation Light from Cosmic-Ray Muons in Liquid Argon

    CERN Document Server

    Whittington, Denver

    2014-01-01

    This paper reports the results of the first experiment to directly measure the properties of the scintillation light generated by minimum ionizing cosmic-ray muons in liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches, as well as for particle identification. The experiment was carried out at the TallBo facility at Fermilab using prototype light guides and electronics developed for the Long-Baseline Neutrino Experiment. Analysis of the time-resolved structure of the scintillation light from cosmic-ray muons gives $\\langle \\tau_{\\text{T}}\\rangle = 1.43 \\pm 0.04~\\text{(stat.)} \\pm 0.007~\\text{(sys.)}~\\mu$s for the triplet light decay time constant. The ratio of singlet to triplet light measured using surface-coated light guides is $R = 0.39 \\pm 0.01~\\text{(stat.)} \\pm 0.008~\\text{(sys.)}$. There is some evidence that this value is not consistent with $R$ for minimum ionizing electrons. However, the value for $...

  7. State-selective radiative recombination cross sections of argon ions

    International Nuclear Information System (INIS)

    The n-, (n,l)- and fine-structure level state-selective radiative recombinations (RR) cross sections of argon ions Ar18+,Ar13+,Ar7+ and Ar+ are obtained with the semi-classical Kramer formula, the relativistic self-consistent field (RSCF) method and the relativistic configuration interaction (RCI) method. It is found that for the highly charged ions with few electrons, the cross sections calculated with these three methods are in good agreement with each other. But as the number of electrons increases, the Kramer formula deviates from the RSCF and RCI results. For instance, when the energy of the incident electron is larger than 100 eV, the n-state selective cross sections of Ar7+ calculated from the Kramer formula are underestimated for more than 50%. The RSCF results are in general agreement with the RCI results. However, for the low charged ions, a clear distinction appears due to the strong configuration interaction, especially near the Cooper minimum. The n-resolved (n≤10) and total Maxwellian averaged rate coefficients are calculated, and the analytic fitting parameters are also provided. -- Highlights: ► The RR cross sections of Ar18+, Ar13+, Ar7+ and Ar+ are obtained. ► The Kramer formula, the relativistic self-consistent field and RCI methods are used. ► Results from three methods are compared with each other.

  8. Electronics calibration board for the ATLAS liquid argon calorimeters

    International Nuclear Information System (INIS)

    To calibrate the energy response of the ATLAS liquid argon calorimeter, an electronics calibration board has been designed; it delivers a signal whose shape is close to the calorimeter ionization current signal with amplitude up to 100 mA in 50 Ω with 16 bit dynamic range. The amplitude of this signal is designed to be uniform over all calorimeters channels, stable in time and with an integral linearity much better that the electronics readout. The various R and D phases and most of the difficulties met are discussed and illustrated by many measurements. The custom design circuits are described and the layout of the ATLAS calibration board presented. The procedure used to qualify the boards is explained and the performance obtained illustrated: a dynamic range up to 3 TeV in three energy scales with an integral linearity better than 0.1% in each of them, a response uniformity better than 0.2% and a stability better than 0.1%. The performance of the board is well within the ATLAS requirements. Finally, in situ measurements done on the ATLAS calorimeter are shown to validate these performances

  9. Methane from benzene in argon dielectric barrier discharge

    International Nuclear Information System (INIS)

    Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

  10. Preliminary Report On Combined Surgical- And Laser-Treatment Of Large Hemangiomas And Tattoos

    Science.gov (United States)

    Ginsbach, G.

    1981-05-01

    As most hemangiomas and tattoos require many sessions to be cured completely by argon-laser or conventional therapy I developed a new combined surgical and laser-therapy method for large hemangiomas and tattoos. This is a three step method. First: The skin lesion is treated by argon-laser with the point by point method, developed by ourself. Second: Under local or general anaesthesia a) the hemangioma is partially excised and undermined letting only the skin which is already treated by argon-laser-beams. Than the hemangioma is exstirpated in toto, the wound closed by running intradermal sutures and a pressure bandage applied, b) the tattoo is abraded as deep as possible, draped by lyofoam. Then a pressure bandage is applied. Third: The hemangioma as well as the tattoo are treated by argon-laser-beams after the operation. This method is safe and effective, gives good results, minimal scars in the case of hemangiomas and tattoos. In this paper the method is described and some cases are illustrated by pre- and postoperational photographs.

  11. Comparison of the treatment of vascular lesions with the copper-vapor laser and flashlamp-pumped dye laser

    Science.gov (United States)

    Flock, Stephen T.; Waner, Milton; McGrew, Ben; Colvin, G. B.; Montague, Donna

    1992-08-01

    Vascular lesions such as port-wine stains and telangiectases are sometimes treated with carbon-dioxide lasers, argon lasers or argon-pumped dye lasers; however these lasers are non- specific in their thermal effect on tissues and as a result often cause significant scarring. Recently, evidence has accumulated that the flashlamp-pumped dye (585 nm) and copper- vapor (578 nm) lasers, which produce pulsed light that is efficiently absorbed by hemoglobin, are more selective in coagulating abnormal vascular tissue and as a result give a superior clinical result. It is not yet clear what the most important physical and biological mechanisms are during the light-tissue interaction mediated by these two lasers. The post-treatment sequence of events is different for tissue irradiated by each laser; most significantly, the flashlamp-pumped dye laser causes significant transient purpura, whereas the copper vapor laser causes blanching and eschar formation. The clinical outcome, that is regression of the lesion, is equally successful with either laser although some evidence has accumulated showing that the flashlamp-pumped dye laser is best suited to the treatment of small vessel disease while the copper-vapor laser is better for the treatment of large vessel disease. In this paper, we will discuss our observations of the treatment of vascular lesions on humans with the copper-vapor and flashlamp-pumped dye lasers using empirically derived efficacious treatment parameters. Mathematical models of light and heat propagation and in vivo experiments involving mice ears and rat skin flaps will be used to elucidate what we feel are the important underlying mechanisms of this vascular lesion laser therapy.

  12. Biochemical Studies Of The Effect Of Two Laser Radiation Wavelengths On The Khapra Beetle Trogoderma Granarium Everts (Coleoptera : Dermestidae)

    Science.gov (United States)

    Abdel-Kader, Mahmoud H.; El-Nozahy, Adel M.; Ahmed, Salwa M. S.; Khalifa, Ibtesam A.

    2007-02-01

    The present work was carried out to evaluate the actual effect of subleathal dosage of LD30 of two different lasers (Argon-ion and CO2 lasers) on the main metabolites, phosphatases enzymes, transaminases, acetylcholinestrase and peroxidases in the one day adult stage of Trogoderma granarium treated as 2-3 days old pupae. Our results clearly indicated that two different wavelengths of laser radiation increased significantly the total proteins content, whereas no significant changes occurred in the total lipids for the two laser radiation wavelenghts. On the other hand the total carbohydrates were significantly decreased when irradiating using CO2 laser wavelength which is not the case for the Argon-ion laser radiation. Significant changes of phosphatases occurred for both wavelengths. Inhibition of transaminases GOT (glutamic oxaloacetic transaminases) and insignificant changes of GPT (glutamic pyruvic oxaloacetic transaminases) was observed for both laser wavelengths. Significant inhibition of acetyl cholinestrase was observed using CO2 laser and insignificant changes were recorded for Argon ion laser radiation where as insignificant decrease of peroxideses was observed for both lasers.

  13. Optically Forbidden Excitations of 3s Electron of Argon by Fast Electron Impact

    Institute of Scientific and Technical Information of China (English)

    朱林繁; 成华东; 刘小井; 田鹏; 苑震生; 李文斌; 徐克尊

    2003-01-01

    The electron energy loss spectrum of argon in the energy region of 24.5-30.5eV was measured at 2.5 keV impact energy. The line profile parameters of the optically forbidden excitations of 3s-1ns (n = 4-6) and 3s-1nd (n = 3-7) of argon, I.e.,Eγ,Г,q and p,were determined.

  14. Benchmarking TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    OpenAIRE

    Baptista, B.; Bugel, L.; Chiu, C; Conrad, J. M.; Ignarra, C. M.; Jones, B. J. P.; Katori, T.; Mufson, S.

    2012-01-01

    Scintillation light from liquid argon is produced at 128 nm and thus must be shifted to visible wavelengths in light detection systems used for Liquid Argon Time Projection Chambers (LArTPCs). To date, designs have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we show that the response of lightguides coated with TPB in a UV Transmitting (UV...

  15. TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    CERN Document Server

    Ignarra, C M

    2013-01-01

    Light detection systems in Liquid Argon Time Projection Chambers (LArTPCs) require the detection of the 128 nm light produced during argon scintillation. Most detectors use Tetraphenyl Butadiene (TPB) to shift the wavelength of the light into a range visible to Photomultiplier Tubes (PMTs). These proceedings summarize characterizations of light-guides coated with a matrix of TPB in UV transmitting acrylic which are more compact than existing LArTPC light collection systems.

  16. TPB-coated light guides for liquid argon TPC light detection systems

    Science.gov (United States)

    Ignarra, C. M.

    2013-10-01

    Light detection systems in Liquid Argon Time Projection Chambers (LArTPCs) require the detection of the 128 nm light produced during argon scintillation. Most detectors use Tetraphenyl Butadiene (TPB) to shift the wavelength of the light into a range visible to Photomultiplier Tubes (PMTs). These proceedings summarize characterizations of light-guides coated with a matrix of TPB in UV transmitting acrylic which are more compact than existing LArTPC light collection systems.

  17. Configurational Entropy,Diffusivity and Potential Energy Landscape in Liquid Argon

    Institute of Scientific and Technical Information of China (English)

    DUAN Yong-Ping; MA Cong-Xiao; LI Jia-Yun; LI Cong; WANG Dan; LI Mei-Li; SUN Min-Hua

    2009-01-01

    The configurational entropy, diffusion coefficient, dynamics and thermodynamics fragility indices of liquid argon are calculated using molecular dynamics simulations at two densities. The relationship between dynamics and thermodynamics properties is studied. The diffusion coefficient depends linearly on configurational entropy, which is consistent with the hypothesis of Adam-Gibbs. The consistence of dynamics and thermodynamics fragility indices demonstrates that dynamical behaviour is governed by thermodynamics behaviour in glass transition of liquid argon.

  18. A correction to Birks' Law in liquid argon ionization chamber simulations for highly ionizing particles

    International Nuclear Information System (INIS)

    We present a study of the performance of Birks' Law in liquid argon ionization chamber simulations as applied to highly ionizing particles, such as particles with multiple electric charges or with magnetic charge. We used Birks' Law to model recombination effects in a GEANT4 simulation of heavy ions in a liquid argon calorimeter. We then compared the simulation to published heavy-ion data to extract a highly ionizing particle correction to Birks' Law.

  19. LArGe: Background suppression using liquid argon (LAr) scintillation for 0$\

    CERN Document Server

    Marco, M D; Schönert, S

    2007-01-01

    Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK Heidelberg are reported. The liquid argon--germanium system (LArGe) is operated as a 4$\\pi$ anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the GERDA experiment which searches for 0$\

  20. The Potassium-Argon Laser Experiment (karle): In Situ Geochronology for Planetary Missions

    Science.gov (United States)

    Cohen, B. A.

    2016-01-01

    Isotopic dating is an essential tool to establish an absolute chronology for geological events. It enables a planet's crystallization history, magmatic evolution, and alteration to be placed into the framework of solar system history. The capability for in situ geochronology will open up the ability for this crucial measurement to be accomplished as part of lander or rover complement. An in situ geochronology package can also complement sample return missions by identifying the most interesting rocks to cache or return to Earth. Appropriate application of in situ dating will enable geochronology on more terrains than can be reached with sample-return missions to the Moon, Mars, asteroids, outer planetary satellites, and other bodies that contain rocky components. The capability of flight instruments to conduct in situ geochronology is called out in the NASA Planetary Science Decadal Survey and the NASA Technology Roadmap as needing development to serve the community's needs. Beagle 2 is the only mission launched to date with the explicit aim to perform in situ K-Ar isotopic dating [1], but it failed to communicate and was lost. The first in situ K-Ar date on Mars, using SAM and APXS measurements on the Cumberland mudstone [2], yielded an age of 4.21 +/- 0.35 Ga and validated the idea of K-Ar dating on other planets, though the Curiosity method is not purpose-built for dating and requires many assumptions that degrade its precision. To get more precise and meaningful ages, multiple groups are developing dedicated in situ dating instruments.