WorldWideScience

Sample records for alleviates laser-induced choroidal

  1. Knockdown of the Placental Growth Factor Gene Inhibits Laser Induced Choroidal Neovascularization in a Murine Model

    Directory of Open Access Journals (Sweden)

    Ramin Nourinia

    2013-01-01

    Full Text Available Purpose: To evaluate the effect of placental growth factor (PlGF gene knockdown in a murine model of laser-induced choroidal neovascularization. Methods: Choroidal neovascularization was induced in the left eyes of 11 mice by infrared laser. Small interfering RNA (siRNA, 20 picomoles/10 μl corresponding to PlGF mRNA was administered intravitreally by Hamilton syringe in all subjects. One month later, fluorescein angiography and histolologic examination were performed. Results: No leakage was apparent in the 11 eyes treated with siRNA cognate to PlGF. The results of histological evaluation were consistent with angiographic findings showing absence of choroidal neovascularization. Conclusion: Knockdown of the PlGF gene can inhibit the growth of laser-induced choroidal neovascularization in mice.

  2. Knockdown of the Placental Growth Factor Gene Inhibits Laser Induced Choroidal Neovascularization in a Murine Model

    OpenAIRE

    Ramin Nourinia; Zahra-Soheila Soheili; Hamid Ahmadieh; Hassan Akrami; Mozhgan Rezaei Kanavi; Shahram Samiei

    2013-01-01

    Purpose: To evaluate the effect of placental growth factor (PlGF) gene knockdown in a murine model of laser-induced choroidal neovascularization. Methods: Choroidal neovascularization was induced in the left eyes of 11 mice by infrared laser. Small interfering RNA (siRNA, 20 picomoles/10 μl) corresponding to PlGF mRNA was administered intravitreally by Hamilton syringe in all subjects. One month later, fluorescein angiography and histolologic examination were performed. Results: No le...

  3. Melissa officinalis extract inhibits laser-induced choroidal neovascularization in a rat model.

    Directory of Open Access Journals (Sweden)

    Eun Kyoung Lee

    Full Text Available PURPOSE: This study investigated the effect of Melissa officinalis extract on laser-induced choroidal neovascularization (CNV in a rat model. The mechanism by which M. officinalis extract acted was also investigated. METHODS: Experimental CNV was induced by laser photocoagulation in Brown Norway rats. An active fraction of the Melissa leaf extract was orally administered (50 or 100 mg/kg/day beginning 3 days before laser photocoagulation and ending 14 days after laser photocoagulation. Optical coherence tomography and fluorescein angiography were performed in vivo to evaluate the thickness and leakage of CNV. Choroidal flat mount and histological analysis were conducted to observe the CNV in vitro. Vascular endothelial growth factor (VEGF, matrix metalloproteinase (MMP-2, and MMP-9 expression were measured in retinal and choroidal-scleral lysates 7 days after laser injury. Moreover, the effect of M. officinalis extract on tertiary-butylhydroperoxide (t-BH-induced VEGF secretion and mRNA levels of VEGF, MMP-2, and MMP-9 were evaluated in human retinal epithelial cells (ARPE-19 as well as in human umbilical vein endothelial cells (HUVECs. RESULTS: The CNV thickness in M. officinalis-treated rats was significantly lower than in vehicle-treated rats by histological analysis. The CNV thickness was 33.93±7.64 µm in the high-dose group (P<0.001, 44.09±12.01 µm in the low-dose group (P = 0.016, and 51.00±12.37 µm in the control group. The proportion of CNV lesions with clinically significant fluorescein leakage was 9.2% in rats treated with high-dose M. officinalis, which was significantly lower than in control rats (53.4%, P<0.001. The levels of VEGF, MMP-2, and MMP-9 were significantly lower in the high-dose group than in the control group. Meanwhile, M. officinalis extract suppressed t-BH-induced transcription of VEGF and MMP-9 in ARPE-19 cells and HUVECs. CONCLUSIONS: Systemic administration of M. officinalis extract suppressed laser-induced

  4. Inhibition of development of laser-induced choroidal neovascularization with suppression of infiltration of macrophages in Smad3-null mice.

    Science.gov (United States)

    Iwanishi, Hiroki; Fujita, Norihito; Tomoyose, Katsuo; Okada, Yuka; Yamanaka, Osamu; Flanders, Kathleen C; Saika, Shizuya

    2016-06-01

    We evaluated the effects of the loss of Smad3 on the development of experimental argon laser-induced choroidal neovascularization (CNV) in mice. An in vitro angiogenesis model was also used to examine the role of transforming growth factor-β1 (TGFβ1)/Smad3 signaling in vessel-like tube formation by human umbilical vein endothelial cells (HUVECs). CNV was induced in eyes of 8-12-week-old B6.129-background Smad3-deficient (KO) mice (n=47) and wild-type (WT) mice (n=47) by argon laser irradiation. Results showed that the size of the CNV induced was significantly smaller in KO mice as compared with WT mice at day 14 as revealed by high-resolution angiography with fluorescein isothiocyanate-dextran. Immunohistochemistry and real-time reverse transcription-polymerase chain reaction of RNA extracted from laser-irradiated choroidal tissues were conducted on specimens at specific timepoints. Invasion of macrophages (F4/80+), but not neutrophils (myeloperoxidase+), and appearance of myofibroblasts (α-smooth muscle actin+) were suppressed in laser-irradiated KO tissues. mRNA expression of inflammation-related factors, that is, vascular endothelial growth factor (VEGF), macrophage-chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) and TGFβ1 in choroidal tissues was suppressed by the loss of Smad3. We then examined the effects of adding a Smad3 inhibitor, SIS3, or an ALK5 inhibitor, SB431542, on tube formation promoted by TGFβ1 or VEGF in HUVECs cocultured with fibroblast feeder. Further addition of SIS3 or SB431542 augmented vessel-like tube formation by HUVECs in the presence of TGFβ1 or VEGF. In conclusion, lack of Smad3 attenuated the growth of laser-induced CNV with suppression of inflammation by macrophages in mice. Because blocking TGFβ1/Smad3 signal stimulated the activity of angiogenesis of HUVECs in vitro, the reduction of CNV in vivo in KO mice is attributed to a decrease in growth factor levels in the tissue by the loss of Smad3. PMID:26950486

  5. Role of complement C3 in laser-induced choroidal neovascularization of rat%激光诱导小鼠脉络膜新生血管中补体C3的作用

    Institute of Scientific and Technical Information of China (English)

    许琴; 肖煜晨

    2011-01-01

    目的 探讨激光诱导脉络膜新生血管(choroidal neovaseulature,CNV)形成机制中补体的作用.方法 用氪红激光对小鼠行实验性视网膜激光光凝,建立CNV动物模型,共聚焦显微镜下观察CNV发生情况,检测补体溶血活性(CH50),用免疫组织化学方法检测补体C3,用RT-PCR分析C3a受体mRNA的表达.结果 激光后第7天,对照组C57BL/6小鼠见CNV形成,而眼镜蛇毒因子(cobra venom factor,CVF)预处理组及C3小鼠组未见CNV形成.CVF预处理组小鼠补体的CH50于激光后第1天、第3天、第5天、第7天分别为2%、3%、3%、2%,同时间点对照组均为100%,差异均有显著统计学意义(均为P小鼠组未见C3阳性染色.激光后对照组C57BL/6小鼠较激光前,C3a受体mRNA表达增强,激光后第5天,C3a受体mRNA水平达到高峰,并在激光后第7天维持较高水平,而CVF预处理组小鼠及缺乏补体C3的C3小鼠组激光前后未见明显改变.结论 氪激光诱导CNV模型,补体C3参与CNV形成.补体系统的存在和激活是激光诱导CNV形成的必要条件.%Objective To study the role of complement C3 in laser-induced choroidal neovascularization (CNV) of rat. Methods CNV model was established by experimental laser photocoagulation with the krypton red laser,the incidence of CNV was determined by confocal microscope,the hemolysis activity (CH50) of complement was detected,and the complement C3 was tested by immunohistochemical method,RT-PCR analysis was used to examine the expression of C3R mRNA. Results At 7 days after laser treatment,CNV was induced successfully in C57/BL6 mice of control group,but no CNV was found in CVF pre-treated group and C3 -/- rat group. The CH50 of complement in CVF pre-treated group at 1 day,3 days,5 days,7 days after laser treatment were 2% , 3% ,3% and 2% .respectively,which in control group were all 100% ,there were significant differences (all P <0.001). At 1 day after laser treatment,the complement C3 was strong positive

  6. A non membrane-targeted human soluble CD59 attenuates choroidal neovascularization in a model of age related macular degeneration.

    Directory of Open Access Journals (Sweden)

    Siobhan M Cashman

    Full Text Available Age related macular degeneration (AMD is the most common cause of blindness amongst the elderly. Approximately 10% of AMD patients suffer from an advanced form of AMD characterized by choroidal neovascularization (CNV. Recent evidence implicates a significant role for complement in the pathogenesis of AMD. Activation of complement terminates in the incorporation of the membrane attack complex (MAC in biological membranes and subsequent cell lysis. Elevated levels of MAC have been documented on choroidal blood vessels and retinal pigment epithelium (RPE of AMD patients. CD59 is a naturally occurring membrane bound inhibitor of MAC formation. Previously we have shown that membrane bound human CD59 delivered to the RPE cells of mice via an adenovirus vector can protect those cells from human complement mediated lysis ex vivo. However, application of those observations to choroidal blood vessels are limited because protection from MAC- mediated lysis was restricted only to the cells originally transduced by the vector. Here we demonstrate that subretinal delivery of an adenovirus vector expressing a transgene for a soluble non-membrane binding form of human CD59 can attenuate the formation of laser-induced choroidal neovascularization and murine MAC formation in mice even when the region of vector delivery is distal to the site of laser induced CNV. Furthermore, this same recombinant transgene delivered to the intravitreal space of mice by an adeno-associated virus vector (AAV can also attenuate laser-induced CNV. To our knowledge, this is the first demonstration of a non-membrane targeting CD59 having biological potency in any animal model of disease in vivo. We propose that the above approaches warrant further exploration as potential approaches for alleviating complement mediated damage to ocular tissues in AMD.

  7. Choroidal OCT

    Science.gov (United States)

    Esmaeelpour, Marieh; Drexler, Wolfgang

    Novel imaging devices, imaging strategies and automated image analysis with optical coherence tomography have improved our understanding of the choroid in health and pathology. Non-invasive in-vivo high resolution choroidal imaging has had its highest impact in the investigation of macular diseases such as diabetes macular edema and age-related macular degeneration. Choroidal thickness may provide a clinically feasible measure of disease stage and treatment success. It will even support disease diagnosis and phenotyping as is demonstrated in this chapter. Utilizing color coded thickness mapping of the choroid and its Sattler's and Haller's layer may further strengthen the sensitivity of the investigation findings.

  8. LASER-INDUCED PHOTODISSOCIATION

    OpenAIRE

    Rahman, N.

    1985-01-01

    The richness of the field of laser-induced photodissociation is pointed out. Some of the recent works in this area comprising theoretical, computational as well as experimental research are discussed.

  9. Choroidal melanoma

    International Nuclear Information System (INIS)

    A useful and practical guide is developed to better track to the uveal melanoma, due to its highly malignant character. Melanoma of the uveal tract (choroid, iris, ciliary body) has been the intraocular tumor most frequent in adults. The biopsy has been inaccessible, due to its location; therefore, the diagnostic should be based on clinical examination and the correct utilization of the diagnostic procedures (ultrasound, fluorescent angiography, computed axial tomography and magnetic resonance). The cases are diagnosed in the histological examination of the operatory piece post-enucleation for other causes. Epidemiological research has been key to determine the associated factors and better to understand the mechanisms of onset of the disease. Anatomopathological studies of choroidal melanoma have permitted to know the natural history of the disease. The decrease of the visual acuity, pain or inflammation are presented as a defect in the visual field. Different techniques to diagnose the disease are explained. Ultrasound in mode A and B, computed axial tomography and magnetic resonance are the diagnostic method of election. Ultrasound has been the primary method of diagnostic, giving the size and vascularisation, useful in tracking, when they are treated in shape conservatively, showing changes in echogenicity and less vascularisation as good response to treatment. The treatments of choroidal melanoma are specified. The correct interpretation of the clinical symptoms and early utilization of diagnostic imaging methods, have permitted to establish the adequate therapeutic and to avoid local and distant metastasis. The uveal melanoma, depending on their size and location, traditionally has been treated by enucleation. Data from the literature and authors, have promoted the conservation of the ocular globe, depending on the size of the tumor. Transpupillary thermotherapy has been an available alternative for small tumors in Costa Rica and level of social security

  10. Modifying Choroidal Neovascularization Development with a Nutritional Supplement in Mice

    OpenAIRE

    Alina Adriana Ivanescu; Patricia Fernández-Robredo; Henar Heras-Mulero; Luis Manuel Sádaba-Echarri; Laura García-García; Vanessa Fernández-García; Maite Moreno-Orduna; Aitor Redondo-Exposito; Sergio Recalde; Alfredo García-Layana

    2015-01-01

    We examined the effect of nutritional supplements (modified Age Related Eye Disease Study (AREDS)-II formulation containing vitamins, minerals, lutein, resveratrol, and omega-3 fatty acids) on choroidal neovascularization (CNV). Supplements were administered alone and combined with intravitreal anti-VEGF in an early-CNV (diode laser-induced) murine model. Sixty mice were evenly divided into group V (oral vehicle, intravitreal saline), group S (oral supplement, intravitreal saline), group V +...

  11. Laser induced plasma spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Suk; Kim, Nak Bae; Woo, Hyung Joo; Kim, Joon Kon; Kim, Gi Dong; Choi, Han Woo; Yoon, Yoon Yeol; Shim, Sang Kwun [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    When the pulsed laser is focused onto a small spot of a solid surface, an optically induced plasma is formed at this surface. This plasma will be formed when the laser power density exceeds the breakdown threshold value of the solid surface. The interaction of high power laser light with a target or solid materials have been an active topic not only in plasma physics but also in the field of analytical chemistry. Recently, LIPS(laser induced plasma spectroscopy) has been applied many kinds of sample analysis including solid, liquid and gas analysis. LIPS has a advantage of the minimal sample preparation required for a solid sample and ability to analyze conducting as well as nonconducting materials, multi-elemental analysis. But this method has a poorer sensitivity than several competing atomic spectroscopic methods and semiquantitative analysis. Numerous factors affect the ablation process, including the laser pulse properties, such as pulse width, spatial and temporal fluctuations of the pulse and laser power fluctuations. The mechanical, physical and chemical properties of the sample also influence the ablation process. We studied LIPS with Nd:YAG second harmonic 532 nm and the induced plasma temperature was studied by observing the emission intensity of Fe(I) line and the plasma temperature of the different kind of samples were calculated using Boltzmann plotting method under same laser condition. Using the above experimental results, LIPS has been applied for the analysis of the elemental distribution mapping of the polished rock section. For the elemental mapping analysis, XY stage controlled by step motor and PC were used and 5 x 5 mm element image was obtained. For the quantitative analysis, rock standard samples were analyzed and Ba, Cu, Fe, Mn, Si and Sr calibration curve were obtained. (author). 22 refs., 2 tabs., 14 figs.

  12. Macular serpiginous choroiditis

    Directory of Open Access Journals (Sweden)

    Sahu Dinesh

    2002-01-01

    Full Text Available Purpose: To report a variant form of serpiginous choroiditis, that initially or predominantly involved the macular area. Methods: Nine eyes of 6 patients with the macular form of serpiginous choroiditis were evaluated clinically and angiographically in a longitudinal fashion for a period of 12-36 months. The active stage and the recurrences were treated by oral and periocular cortico steroids; and two patients were supplemented with oral azathioprine. Most of these patients were referred to our center with varied diagnoses. Results: In this group, 4 were male and 2 were female with an average age of 30.5 years. Three patients had bilateral macular lesions, two had typical serpiginous choroiditis in the fellow eye and the remaining one had unilateral macular involvement alone. The initial visual acuity was 6/60 or less in 60% eyes whereas the final visual acuity was 6/18 or better in 66% eyes. Angiographic findings were typical of serpiginous choroiditis characterised by early hypofluorescence followed by leakage and staining of the borders and the lesion itself without any evidence of choroidal ischaemia or retinal vascular abnormalities. Conclusion: The macular variant of serpiginous choroiditis can mimic many other macular pathologic lesions, thus posing a diagnostic dilemma. Because of its relentless destructive course, early diagnosis and prompt treatment is required to prevent sight-threatening complications.

  13. Circumscribed choroidal hemangioma

    Directory of Open Access Journals (Sweden)

    Saeed Karimi

    2015-01-01

    Full Text Available Circumscribed choroidal hemangiomas are benign vascular hamartomas without systemic associations. Generally, they are orange-red elevated masses, which are found posterior to the equator. Lesions are usually solitary and unilateral. Overlying subretinal fluid, serous retinal detachment and cystoid macular edema are common findings. Intravenous fluorescein angiography, indocyanine green angiography, ultrasonography, optical coherence tomography and enhanced depth imaging are helpful ancillary tests for diagnosis of circumscribed choroidal hemangiomas. Asymptomatic circumscribed choroidal hemangiomas do not require treatment. For symptomatic lesions with exudative retinal detachment or cystoid macular edema, photodynamic therapy has emerged as the treatment of choice with high rates of tumor regression, subretinal fluid resorption and minimal complications. Lens-sparing external beam radiotherapy, plaque brachytherapy, proton beam therapy, stereotactic radiosurgery, transpupillary thermotherapy, laser photocoagulation and anti-VEGF injections are other treatment modalities.

  14. Transvitreal retino-choroidal biopsy of suspected malignant lesions of the choroid

    DEFF Research Database (Denmark)

    Jensen, O.A.; Prause, J.U.; Scherfig, E.

    ophthalmology, intraocular biopsy, transvitreal retino-choroidal biopsy, malignant melanoma of choroid, histopathology, brachytherapy......ophthalmology, intraocular biopsy, transvitreal retino-choroidal biopsy, malignant melanoma of choroid, histopathology, brachytherapy...

  15. Central areolar choroidal dystrophy.

    NARCIS (Netherlands)

    Boon, C.J.F.; Klevering, B.J.; Cremers, F.P.M.; Zonneveld-Vrieling, M.N.; Theelen, T.; Hollander, A.I. den; Hoyng, C.B.

    2009-01-01

    OBJECTIVE: To describe the clinical characteristics, follow-up data and molecular genetic background in a large group of patients with central areolar choroidal dystrophy (CACD). DESIGN: Retrospective case series study. PARTICIPANTS: One hundred three patients with CACD from the Netherlands. METHODS

  16. A Case of Choroidal Tubercles

    Institute of Scientific and Technical Information of China (English)

    Chaoran Zhang

    2004-01-01

    Purpose: To report a case of choroidal tubercles in a miliary tuberculosis boy.Method: Clinical features description.Results: A 14-year-old boy was found to have multifocal choroidal tubercles. Angiography was performed. He was followed up for 12 months. The choroidal lesions regressed after using anti-tuberculosis drugs for 8 months. Pigment changes remained. Conclusion: Tuberculosis may present as a posterior segment inflammation. In miliary tuberculosis, choroid is also a target tissue. Eye Science 2004;20:23-24.

  17. Malignant melanoma of choroid

    Directory of Open Access Journals (Sweden)

    Manohar S

    1991-01-01

    Full Text Available Four cases of malignant melanoma of the choroid are reported due to rarity of the condition in India. One of the cases presented with Naevus of Ota. All the cases had typical clinical and investigative features. All cases were enucleated. Histopathologically three of them were of mixed type and one was of the epithelioid type. Two of the cases were seen in patients below 40 years of age.

  18. Suppression of Experimental Choroidal Neovascularization by Curcumin in Mice

    Science.gov (United States)

    Xie, Ping; Zhang, WeiWei; Yuan, Songtao; Chen, Zhiqiang; Yang, Qin; Yuan, DongQing; Wang, Feng; Liu, QingHuai

    2012-01-01

    Purpose To investigate the effects of curcumin on the development of experimental choroidal neovascularization (CNV) with underlying cellular and molecular mechanisms. Methods C57BL/6N mice were pretreated with intraperitoneal injections of curcumin daily for 3 days prior to laser-induced CNV, and the drug treatments were continued until the end of the study. The CNV area was analyzed by fluorescein-labeled dextran angiography of retinal pigment epithelium (RPE)-choroid flat mounts on day 7 and 14, and CNV leakage was evaluated by fluorescein angiography (FA) on day 14 after laser photocoagulation. The infiltration of F4/80 positive macrophages and GR-1 positive granulocytes were evaluated by immunohistochemistry on RPE-choroid flat mounts on day 3. Their expression in RPE-choroid complex was quantified by real-time PCR (F4/80) and Western blotting (GR-1) on day 3. RPE-choroid levels of vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1, and intercellular adhesion molecule (ICAM)-1 were examined by ELISA on day 3. Double immunostaining of F4/80 and VEGF was performed on cryo-sections of CNV lesions on day 3. The expression of nuclear factor (NF)-κB and hypoxia-inducible factor (HIF)−1α in the RPE-choroid was determined by Western blotting. Results Curcumin-treated mice had significantly less CNV area (PCurcumin treatment led to significant inhibition of F4/80 positive macrophages (Pcurcumin treatment (PCurcumin inhibited the RPE-choroid levels of TNF-α (PCurcumin treatment led to the suppression of CNV development together with inflammatory and angiogenic processes including NF-κB and HIF−1α activation, the up-regulation of inflammatory and angiogenic cytokines, and infiltrating macrophages and granulocytes. This provides molecular and cellular evidence of the validity of curcumin supplementation as a therapeutic strategy for the suppression of age-related macular degeneration (AMD

  19. Macrophage polarization in experimental and clinical choroidal neovascularization

    Science.gov (United States)

    Yang, Yu; Liu, Fang; Tang, Miao; Yuan, Miner; Hu, Andina; Zhan, Zongyi; Li, Zijing; Li, Jiaqing; Ding, Xiaoyan; Lu, Lin

    2016-01-01

    Macrophages play an important role in the development of age-related macular degeneration (AMD). In this study, the spatial and temporal changes and the polarization of macrophages in murine laser-induced choroidal neovascularization (CNV) were investigated, and the polarized M1 and M2 biomarkers in the aqueous humors of neovascular AMD (nAMD) patients were studied. Macrophages, the main infiltrating inflammatory cells in CNV lesions, were evidenced by a significant increase in F4/80 mRNA expression and by the infiltration of F4/80+ cells in the lesions and the vicinity of laser-induced CNV. The mRNA expressions of M1-related markers were dramatically upregulated in the early stage, while the M2-related markers were slightly upregulated in the middle stage and sustained until the late stage. The results of immunostaining showed a similar early-but-transient M1 pattern and a delayed-but-sustained M2 pattern in laser-induced CNV. In addition, a higher M2/M1 ratio was found in both the murine models (Arg-1/iNOS and CCL22/CXCL10) and the aqueous humors of nAMD patients (CCL22/CXCL10) than in the controls. Our results suggested that the dynamic patterns of M1 and M2 were different in both the experimental and clinical CNV. The M2 macrophages were predominant and may play a more important role in the development of CNV. PMID:27489096

  20. Choroidal thickness after intravitreal ranibizumab injections for choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Ellabban AA

    2012-05-01

    Full Text Available Abdallah A Ellabban, Akitaka Tsujikawa, Ken Ogino, Sotaro Ooto, Kenji Yamashiro, Akio Oishi, Nagahisa YoshimuraDepartment of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, JapanPurpose: To study changes in choroidal thickness with ranibizumab treatment for choroidal neovascularization (CNV.Design: Prospective case series.Methods: This prospective study consisted of 60 CNV-affected eyes of 60 patients treated with intravitreal injections of ranibizumab using an on-demand protocol after an initial loading phase. The eyes studied included 20 with age-related macular degeneration (AMD, 20 with polypoidal choroidal vasculopathy (PCV, and 20 with myopic CNV. In the eyes with AMD and PCV, choroidal thickness at the fovea was measured with optical coherence tomography using enhanced depth imaging. In eyes with myopic CNV, the choroidal thickness was measured using standard optical coherence tomography without the enhanced depth imaging technique.Results: With ranibizumab treatment, central retinal thickness decreased significantly (P < 0.001 and visual acuity improved significantly (P < 0.001. However, central choroidal thickness (167.2 ± 108.3 µm showed no significant change at 1 month after the loading phase (165.2 ± 107.8 µm, P = 0.120 or at final examination (164.8 ± 107.7 µm, P = 0.115. At baseline, central retinal thickness in eyes with AMD was significantly greater that those with PCV (P = 0.005 or high myopia (P = 0.029. However, central choroidal thickness in eyes with myopic CNV was significantly thinner than in eyes with AMD (P < 0.001 or PCV (P < 0.001. In each type of disease, there was no significant change in central choroidal thickness with ranibizumab treatment.Conclusion: The effect of ranibizumab on the choroidal thickness is minimal, if any.Keywords: choroidal thickness, ranibizumab, optical coherence tomography

  1. 频域光学相干断层扫描对激光诱导的大鼠脉络膜新生血管的定量测量%Quantitative measurement of laser-induced choroidal neovascularization with spectral-domain optical coherent tomography

    Institute of Scientific and Technical Information of China (English)

    王雯秋; 汪枫桦; 王泓; 宋正宇; 吴颖; 孙晓东

    2012-01-01

    Background The neovascular form of the disease usually causes severe vision loss in a number of eye diseases.Special-domain optical coherence tomography (SD-OCT) provides high-quality in retinal imaging and the possibility of the measurement in vivo.Objective This study aimed to investigate the feasibility of SD-OCT dynamically measuring choroidal neovascularization (CNV).Methods CNV was induced in 30 left eyes of 30 clean Brown Norway(BN)rats by retinal photocoagulation with the laser parameter as follows: wavelength 532 nm,exciting power 200 mW,spot diameter 100 μm and irradiating time 50 ms.Bubble or less retinal bleeding was thought as Brunch membrane breakage and CNV model establishment.Fundus fluorescein angiography(FFA) was performed to determine the establishment of CNV model and scored based on the fluorescein leakage on 3,7,14,21 days after photocoagulation.Meanwhile,CNV memberane thickness (CMT) was dynamically measured in vivo as the maxiume value from retinal inner limiting membrane through choroidal vessel layer in various time points.Histopathologic examination was used in the 14th day to evaluate and verify the result of SD-OCT.The right eyes were as controls.Results FFA examination showed that disc-like leakage of fluorescein appeared in 7 days and extended in 14 days after photocoagulation with the scores of 1.6±0.4,2.5±0.6 and 2.4±0.5 in 7,14 and 21 days,showing a significant difference among them(F=13.11,P<0.01).The fluorescein leakage score was significantly higher in 14 and 21 days than that of 7 days(both P<0.05).CMT measured by SD-OCT was(76.33±10.09),(102.03±14.21)and(98.03±13.76) μm in 7,14 and 21 days after photocoagulation respectively,with a significant difference among 3 time points (F=23.25,P<0.01),and that in 14 and 21 days was significantly declined in comparison with 7 days(both P<0.05).The results of SD-OCT showed a consistent tendency with that of FFA.Histopathological examination showed CNV formation in 14 days

  2. Laser-induced damage in optical materials

    CERN Document Server

    Ristau, Detlev

    2014-01-01

    Dedicated to users and developers of high-powered systems, Laser-Induced Damage in Optical Materials focuses on the research field of laser-induced damage and explores the significant and steady growth of applications for high-power lasers in the academic, industrial, and military arenas. Written by renowned experts in the field, this book concentrates on the major topics of laser-induced damage in optical materials and most specifically addresses research in laser damage that occurs in the bulk and on the surface or the coating of optical components. It considers key issues in the field of hi

  3. Laser-induced plasma temperature

    International Nuclear Information System (INIS)

    It is of great importance to explore the evolution of laser-induced plasma (LIP) properties, especially plasma temperature, with regard to variations of experiment conditions in both theoretical study and routine applications. By investigating the influence of various factors on plasma temperature, one can gain knowledge about the processes in plasma and adjust experimental conditions to obtain optimum analytical performance. Herein the fundamental theories and calculation methods of LIP temperature via spectroscopic approaches are briefly reviewed. Its temporal and spatial evolutions together with several influencing factors are discussed, such as laser parameters, ambient surrounding, and physical and chemical properties of the sample. The results summarized exhibit the general trend that LIP temperature increases with increasing laser wavelength, pulse width, laser energy, background gas pressure, and sample hardness. On the other hand, it decreases with time elapsing and distance from sample surface. Moreover, plasma temperature generated in argon surrounding is higher than that in other gas species, and the rank of temperature values generated from different samples exhibits a general tendency of Cu > Fe > Ni ≈ Al ≈ glass ≈ rock. Additionally, LIP temperature tends to increase as lens focal point approaches sample surface, and the plasma confinement effect in sample cavity is significant in altering plasma temperature. Various explanations are given to interpret these temperature behaviors. - Highlights: • Fundamental theories and calculation methods of LIP temperature are reviewed. • Influences of various factors on LIP temperature are discussed. • Various explanations are given to interpret the temperature behaviors

  4. Choroidal neovascular membrane associated with choroidal osteoma (CO treated with trans-pupillary thermo therapy.

    Directory of Open Access Journals (Sweden)

    Sharma Sumita

    2004-01-01

    Full Text Available Choroidal neovascular membrane, a known complication of choroidal osteoma causing visual loss when located subfoveally, can be successfully treated with transpupillary thermo therapy.

  5. Laser-induced chemical reactions

    International Nuclear Information System (INIS)

    A classical model for the interaction of laser radiation with a molecular system is derived. This model is used to study the enhancement of a chemical reaction via a collision induced absorption. It was found that an infrared laser will in general enhance the rate of a chemical reaction, even if the reactants are infrared inactive. Results for an illustrative analytically solvable model are presented, as well as results from classical trajectory studies on a number of systems. The collision induced absorption spectrum in these systems can be written as the Fourier transform of a particular dipole correlation function. This is used to obtain the collision induced absorption spectrum for a state-selected, mono-energetic reactive collision system. Examples treated are a one-dimensional barrier problem, reactive and nonreactive collisions of H + H2, and a modified H + H2 potential energy surface which leads to a collision intermediate. An extension of the classical model to treat laser-induced electronically nonadiabatic collision processes is constructed. The model treats all degrees of freedom, molecular, electronic and radiation, in a dynamically consistent framework within classical mechanics. Application is made to several systems. Several interesting phenomena are discovered including a Franck-Condon-like effect causing maxima in the reaction probability at energies much below the classical threshold, laser de-enhancement of chemical reactions and an isotope effect. In order to assess the validity of the classical model for electronically nonadiabatic process (without a laser field), a model problem involving energy transfer in a collinear atom-diatom system is studied, and the results compared to the available quantum mechanical calculation. The calculations are in qualitative agreement

  6. Intravitreal bevacizumab monotherapy for choroidal neovascularisation secondary to choroidal osteoma.

    Science.gov (United States)

    Papastefanou, V P; Pefkianaki, M; Al Harby, L; Arora, A K; Cohen, V M L; Andrews, R M; Sagoo, M S

    2016-06-01

    PurposeThe purpose of this study is to present the outcomes of a series of patients with choroidal neovascular membrane (choroidal neovascularisation (CNV)) secondary to a choroidal osteoma undergoing anti-VEGF monotherapy.Patients and methodsRetrospective series of patients with choroidal neovascularization secondary to choroidal osteoma. All patients underwent clinical and imaging assessment (fundus photo, B-scan ultrasonography, fluorescein angiography, and optical coherence tomography-where available), and were managed with intravitreal anti-VEGF injections (Bevacizumab). Visual acuity and central retinal thickness were recorded pre treatment and at the end of the follow-up period.ResultsEight patients were included in this study. Of this, 6/8 had predominantly classic or classic and 2/8 patients had minimally classic or occult CNV. Each patient received 3-10 injections of bevacizumab. Median follow-up was 9 months (3-15 months). Visual acuity improved in 5 patients, by 2-6 Snellen lines. CNV completely regressed in 5 cases and partially regressed in 3 cases. Mean CRT reduction was 122 μm (6 to -230 μm).ConclusionIntravitreal bevacizumab can be an effective treatment modality in the management of vision threatening CNV secondary to choroidal osteoma. PMID:27034203

  7. Choroidal neovascularization is inhibited via an intraocular decrease of inflammatory cells in mice lacking complement component C3

    OpenAIRE

    Xue Tan; Katsuhito Fujiu; Ichiro Manabe; Junko Nishida; Reiko Yamagishi; Ryozo Nagai; Yasuo Yanagi

    2015-01-01

    In early age-related macular degeneration (AMD), complement component C3 can be observed in drusen, which is the accumulation of material beneath the retinal pigment epithelium. The complement pathways, via the activation of C3, can upregulate the expression of cytokines and their receptors and the recruitment of inflammatory leukocytes, both of which play an important role in the development of choroidal neovascularization (CNV) in exudative AMD. Laser-induced CNV lesions were found to be si...

  8. Pediatric choroid plexus neoplasms

    International Nuclear Information System (INIS)

    Purpose: Choroid plexus tumors (CPT) are rare childhood neoplasms. The relatively small number of reported cases and the controversies surrounding the clinical and pathological classification of these tumors have made it difficult to define a standard of care for these patients. Our intention is to contribute to the body of knowledge of these tumors and further define the role of adjuvant therapy. Methods and Materials: We performed a retrospective review of 14 children with choroid plexus neoplasms referred to St. Jude Children's Research Hospital between October 1985 and December 1987. Ten patients had choroid plexus carcinoma (CPC) based on pathologic criteria and evidence of brain invasion at surgery or leptomeningeal disease (M+); 4 patients had choroid plexus papilloma (CPP). Patients with CPP were initially treated with surgery alone whereas patients with CPC were generally treated with postoperative therapy that included chemotherapy (CT) and/or craniospinal irradiation (CSI) with a focal boost to the primary site. For most patients CT consisted of combinations of cyclophosphamide, etoposide, vincristine, and a platinum agent. The median CSI dose was 35.2 Gy (range 24-46.2 Gy). The median primary site dose was 55.2 Gy (range 49.6-64 Gy). Results: Seven of the 10 CPC cases presented with leptomeningeal dissemination; two of these patients have succumbed to disease. Of the 3 patients with M0 status, all are alive with no evidence of disease (NED). The medial time to relapse from the time of surgery was 5.3 mo (range 3-25 mo). Seven CPC patients were treated with gross total resection (GTR). Three of these patients (2 M0, 1 M+) received CT without CSI and are currently NED (27, 69, and 60 mo respectively). One M+ patient progressed on CT and has stable disease after CSI (6 mo), one (M0) received CT and CSI and is NED (120 mo), one (M+) is currently on CT with objective response (3 mo) and one (M+) died of progressive disease (24.5 mo) despite CT and CSI. Three

  9. Expulsive choroidal haemorrhage

    Directory of Open Access Journals (Sweden)

    Srinivasan M

    1992-01-01

    Full Text Available Expulsive choroidal haemorrhage is a dramatic and serious complication of cataract surgery that occurred in five patients out of ten thousand consecutive cataract surgeries performed by the author during the year 1989 and 1990. Report about this dreaded complication after cataract surgery are scanty and as far as I can remember I have not seen any report in Indian ophthalmic literature recently. Since cataract surgery forms the major part of intra ocular surgeries performed in our country, I thought it would be appropriate to report about this rare complication which may occur to all of us. Out of five cases 3 were males and 2 were females in the age group ranging between 45-72 years. Two eyes regained vision up to 6/12 after intra operative expulsive haemorrhage. All the eyes were salvaged by doing anterior sclerotomy. Diabetes, hypertension, glaucoma and myopia are the commonest predisposing factors.

  10. Inflammatory Choroidal Neovascularization

    Science.gov (United States)

    Neri, Piergiorgi; Lettieri, Marta; Fortuna, Cinzia; Manoni, Mara; Giovannini, Alfonso

    2009-01-01

    Purpose and Methods: Choroidal neovascularization (CNV) can be a severe sight-threatening sequela, which can be secondary to both infectious and noninfectious uveitis. This review summarizes the different diseases associated with CNV, highlighting new treatment modalities and the possible strategies, which could be applied for the therapy of this occurrence. Results: Since CNV can often originate from posterior pole lesions and can be hard to identify, an accurate examination is mandatory in order to identify the correct diagnosis. In the majority of cases, fluorescein angiography (FA), indocyanine green angiography (ICGA) and optical coherence tomography (OCT) enable the determination of the clinical characteristics of the CNV. An infectious disease should be looked for to include a suitable therapy when available. The treatment strategy for CNV secondary to noninfectious uveal inflammations should be directed at controlling the inflammatory process. Systemic corticosteroids with or without immunosuppressive agents are indicated even when the CNV occurs with apparently inactive uveitis: Chronic subclinical inflammation can be the basis for the pathogenesis of CNV. Additional therapies aimed directly at the neovascular process, such as the intravitreal anti-Vascular Endothelial Growth Factor (VEGF) agents, are recommended particularly when the therapy shows an insufficient response. Conclusion: CNV secondary to uveitis is a severe sequela leading to significant visual impairment. ICGA is mandatory in order to obtain relevant information about the choroidal status. Several therapeutic options have been considered, but no guidelines are provided at the moment. Moreover, the current data are still only based on case reports or small series. For such reasons, further trials are mandatory to validate the preliminary available results. PMID:20404991

  11. Inflammatory choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Neri Piergiorgio

    2009-01-01

    Full Text Available Purpose and Methods: Choroidal neovascularization (CNV can be a severe sight-threatening sequela, which can be secondary to both infectious and noninfectious uveitis. This review summarizes the different diseases associated with CNV, highlighting new treatment modalities and the possible strategies, which could be applied for the therapy of this occurrence. Results: Since CNV can often originate from posterior pole lesions and can be hard to identify, an accurate examination is mandatory in order to identify the correct diagnosis. In the majority of cases, fluorescein angiography (FA, indocyanine green angiography (ICGA and optical coherence tomography (OCT enable the determination of the clinical characteristics of the CNV. An infectious disease should be looked for to include a suitable therapy when available. The treatment strategy for CNV secondary to noninfectious uveal inflammations should be directed at controlling the inflammatory process. Systemic corticosteroids with or without immunosuppressive agents are indicated even when the CNV occurs with apparently inactive uveitis: Chronic subclinical inflammation can be the basis for the pathogenesis of CNV. Additional therapies aimed directly at the neovascular process, such as the intravitreal anti-Vascular Endothelial Growth Factor (VEGF agents, are recommended particularly when the therapy shows an insufficient response. Conclusion: CNV secondary to uveitis is a severe sequela leading to significant visual impairment. ICGA is mandatory in order to obtain relevant information about the choroidal status. Several therapeutic options have been considered, but no guidelines are provided at the moment. Moreover, the current data are still only based on case reports or small series. For such reasons, further trials are mandatory to validate the preliminary available results.

  12. Peripapillary choroidal thickness in childhood.

    Science.gov (United States)

    Read, Scott A; Alonso-Caneiro, David; Vincent, Stephen J; Collins, Michael J

    2015-06-01

    Changes in the thickness of the invivo peripapillary choroid have been documented in a range of ocular conditions in adults; however, choroidal thickness in the peripapillary region of children has not been examined in detail. This study therefore aimed to investigate the thickness of the peripapillary choroid and the overlying retinal nerve fibre layer (RNFL) in a population of normal children with a range of refractive errors. Ninety-three children (37 myopes and 56 non-myopes) aged between 11 and 16 years, had measurements of peripapillary choroidal and RNFL thickness derived from enhanced depth imaging optical coherence tomography images (EDI-OCT, Heidelberg Spectralis). The average thickness was determined in a series of five 0.25 mm width concentric annuli (each divided into 8 equal sized 45° sectors) centred on the optic nerve head boundary, accounting for individual ocular magnification factors and the disc-fovea angle. Significant variations in peripapillary choroidal thickness were found to occur with both annulus location (p annuli of the nasal and temporal sectors respectively (p < 0.001). RNFL thickness also varied significantly with annulus location and sector (p < 0.001), and showed differences in thickness distribution associated with refractive error. This study establishes the normal variations in the thickness of the peripapillary choroid with radial distance and azimuthal angle from the optic nerve head boundary. A significant thinning of the peripapillary choroid associated with myopia in childhood was also observed in both nasal and temporal regions. The changes in peripapillary RNFL and choroidal thickness associated with refractive error are consistent with a redistribution of these tissues occurring with myopic axial elongation in childhood. PMID:25749004

  13. Choroidal excavation with polypoidal choroidal vasculopathy: a case report

    Directory of Open Access Journals (Sweden)

    Kobayashi W

    2012-08-01

    Full Text Available Wataru Kobayashi,1 Toshiaki Abe,2 Hiroshi Tamai,1 Toru Nakazawa11Department of Ophthalmology, 2Division of Clinical Cell Therapy, Center for Advanced Medical Research and Development (ART, Tohoku University Graduate School of Medical Science, Sendai, JapanPurpose: This is a report of a case of choroidal excavation accompanied by polypoidal choroidal vasculopathy (PCV and retinal pigment epithelium detachment (PED.Methods: A 57-year-old Japanese woman who had begun complaining of metamorphopsia in her left eye 7 months earlier underwent spectral-domain optical coherence tomography (SD-OCT, fluorescein angiography (FA, and indocyanine green angiography (IA, as well as a routine ophthalmological examination.Results: The patient’s intraocular pressure, visual acuity, and visual field were within normal range. Ophthalmoscopy revealed a serous macular detachment, soft drusen, exudates, and a reddish-orange elevated lesion in the macula of the left eye. The right eye was normal. SD-OCT revealed two lesions in the left eye. One was a PED accompanied by a notch sign, and the other was a choroidal excavation. Additionally, FA revealed a window defect in the PED, and IA showed typical PCV. Three monthly injections of antivascular endothelial growth factor preserved visual acuity, but failed to have any visible effect on the lesion during the 6-month follow up period.Conclusions: This is the first report of choroidal excavation accompanied by PED and PCV. The data suggest that choroidal excavation may be associated with various changes that have not been previously reported. Careful observation of such cases may therefore be necessary.Keywords: choroidal excavation, polypoidal choroidal vasculopathy, anti-vascular endothelial growth factor treatment

  14. Laser-induced tobacco protoplast fusion

    Institute of Scientific and Technical Information of China (English)

    李银妹; 关力劼; 楼立人; 崔国强; 姚湲; 王浩威; 操传顺; 鲁润龙; 陈曦

    1999-01-01

    Laser tweezers can manipulate small particles, such as cells and organdies. When coupling them with laser microbeam selective fusion of two tobacco protoplasts containing some chloroplast was achieved. Physical and biological variables that affect laser trapping and laser-induced fusion were also discussed. The results show that the effect of chloroplast content and distribution on the yield of cell fusion is remarkable.

  15. Choroidal Nevus in an Eye with Polypoidal Choroidal Vasculopathy

    Directory of Open Access Journals (Sweden)

    Kazunobu Asao

    2014-12-01

    Full Text Available Purpose: To report an eye with polypoidal choroidal vasculopathy (PCV and a choroidal nevus. Methods: This is an observational case report. Results: A healthy 69-year-old woman was referred to the Osaka University Hospital with a diagnosis of a macular tumor. She complained of having distorted vision in her left eye. The medical history of the patient was unremarkable. At the initial examination, her best-corrected visual acuity (BCVA was 20/20 in both eyes, and the intraocular pressure was 18 mm Hg in both eyes. A slit-lamp examination showed no abnormalities in the anterior segment of both eyes and a fundus examination of the left eye showed a slightly elevated juxtafoveal chorioretinal lesion and polyp-like reddish-orange lesions. The juxtafoveal choroidal lesion was located beneath a choroidal neovascularization (CNV. An optical coherence tomography confirmed CNV with pigment epithelial detachment (PED. Fluorescein angiography showed juxtafoveal hyperfluorescence due to CNV. Indocyanine green angiography demonstrated a branching choroidal vascular network that resembled polypoidal lesions. A fundus autofluorescence showed a mosaic pattern and a slight hyperautofluorescence at the CNV. We diagnosed the patient as having PCV. Aflibercept was injected intravitreally because of her PED. After the injection, PED improved and her visual acuity remained stable during the 12-month follow-up period. Conclusions: In cases of PCV, FAF images are helpful in determining the status of the posterior pole. Intravitreal injections of aflibercept can improve PED associated with CNV, and the BCVA will remain stable for at least 12 months.

  16. Laser-Induced Spallation of Microsphere Monolayers

    OpenAIRE

    Hiraiwa, Morgan; Stossel, Melicent; Khanolkar, Amey; Wang, Junlan; Boechler, Nicholas

    2016-01-01

    The detachment of a semi-ordered monolayer of polystyrene microspheres adhered to an aluminum-coated glass substrate is studied using a laser-induced spallation technique. The microsphere-substrate adhesion force is estimated from substrate surface displacement measurements obtained using optical interferometry, and a rigid-body model that accounts for the inertia of the microspheres. The estimated adhesion force is compared with estimates obtained from interferometric measurement of the out-...

  17. Femtosecond Laser Induced Underwater Superoleophobic Surfaces

    OpenAIRE

    Yong Jiale; Chen Feng; Yang Qing

    2015-01-01

    Femtosecond laser microfabrication has been recently utilized in interface science to modify the liquid wettability of solid surfaces. Silicon surface with hierarchical micro/nanostructure is fabricated by a femtosecond laser. Similar to the fish’s scales, the laser-induced surface shows superhydrophilicity in air and superoleophobicity underwater. The oil contact angles can reach up to 159.4 ± 1° for the 1,2-dichloroethane droplets in water. Besides, the surface exhibits ultralow oil-adhesio...

  18. Morphologic Characteristics of Choroid in the Major Choroidal Thickening Diseases, Studied by Optical Coherence Tomography.

    Science.gov (United States)

    Lee, Hoyoung; Bae, Kunho; Kang, Se Woong; Woo, Se Joon; Ryoo, Na-Kyung; Kim, Sang Jin; Han, Gyule

    2016-01-01

    We investigated morphologic features of choroid in the choroidal thickening diseases, including central serous chorioretinopathy (CSC), polypoidal choroidal vasculopathy (PCV), and Vogt-Koyanagi-Harada disease (VKH), by a novel tomographic classification system of the choroid. This cross-sectional study involved 30 patients with active CSC, 30 patients with active PCV, and 27 patients with active VKH, and 30 normal controls. Utilizing enhanced depth imaging optical coherence tomography, we classified the morphology of the choroid into five categories: 1) Standard (S), 2) Dilated outer layer and Attenuated inner layer (DA), 3) Darkened (D), 4) Marbled (M), and 5) Pauci-Vascular (PV) types. Additional tomographic characteristics of the choroid such as choroidal vascular dilation, convolution, scleral invisibility, and choroidal hyper- or hypo-thickening were identified as well. The distribution of five choroidal tomographic morphology and additional tomographic characteristics in each group were analyzed. The DA type was observed in the CSC group more frequently than in the normal control group (53.3% vs 3.3%, P invisibility (70.4%) than controls (0% for all three findings). In conclusion, CSC and PCV shared common morphologic characteristics of choroid, including dilated outer vascular layer and focally attenuated innermost layer. Dense hypo-reflectivity and convolution of choroid were the specific tomographic markers for acute VKH. A new tomographic classification system of choroid may provide discrimination ability and insight into major pachychoroidopathies. PMID:26766530

  19. Long-term outcomes of intravitreal injection of bevacizumab for choroidal neovascularization associated with choroidal osteoma

    OpenAIRE

    Yoshikawa, Tadanobu; Takahashi, Kanji

    2015-01-01

    Purpose To describe the outcomes of intravitreal injections of bevacizumab for choroidal neovascularization (CNV) associated with choroidal osteoma. Methods Retrospective consecutive case series. Three eyes of three patients were studied. All patients were treated with intravitreal injections of bevacizumab for CNV associated with choroidal osteoma. Best-corrected visual acuity, central foveal thickness, tumor thickness on spectral domain optical coherence tomography, and subretinal pigmentat...

  20. Unusual Orange-Colored Choroidal Metastases

    Directory of Open Access Journals (Sweden)

    Hatem Krema

    2013-01-01

    Full Text Available Purpose: To report the clinical and paraclinical features of two patients with orangecolored choroidal metastases in whom the primary cancers have not previously been associated with such lesions. Case Report: Orange-colored choroidal lesions were detected on the fundus examination of one patient with metastatic small cell neuroendocrine tumor of the larynx and oropharynx, and in another subject with metastatic alveolar soft part sarcoma of the leg. Although ultrasonographic characteristics of the choroidal masses were comparable to those of choroidal hemangiomas, fluorescein angiography revealed delayed initial fluorescence along with minimal fluorescence in subsequent phases of the angiogram which were in clear distinction from the earlier appearing and progressively intense fluorescence observed with circumscribed choroidal hemangiomas. Conclusion: Small cell neuroendocrine tumors and alveolar soft part sarcomas should be considered among the differential diagnoses for orange-colored choroidal metastases. Identifying these choroidal lesions could facilitate localizing the occult primary tumor. Fluorescein angiography may differentiate a unifocal orange choroidal metastasis from a circumscribed choroidal hemangioma.

  1. Clinical applications of choroidal imaging technologies

    Directory of Open Access Journals (Sweden)

    Jay Chhablani

    2015-01-01

    Full Text Available Choroid supplies the major blood supply to the eye, especially the outer retinal structures. Its understanding has significantly improved with the advent of advanced imaging modalities such as enhanced depth imaging technique and the newer swept source optical coherence tomography. Recent literature reports the findings of choroidal changes, quantitative as well as qualitative, in various chorioretinal disorders. This review article describes applications of choroidal imaging in the management of common diseases such as age-related macular degeneration, high myopia, central serous chorioretinopathy, chorioretinal inflammatory diseases, and tumors. This article briefly discusses future directions in choroidal imaging including angiography.

  2. The Abnormal Choroidal Vessels in Aged Patients

    Institute of Scientific and Technical Information of China (English)

    Shizhou Huang; Feng Wen; Dezheng Wu; Guangwei Luo; Caijiao Liu

    2002-01-01

    Background: To show the abnormal choroidal vessels in aged patients with indocyanine-green angiography (ICGA).Methods: ICGA was performed in 350 patients with TOPCON TRC-50IA fundus camera.The images were recorded and retrospectively reviewed.Results: Five aged patients out of 350 cases were found to have abnormal choroidalvessels. The incidence was 1.43%. The abnormal choroidal vessels showed round- shapet,focal enlargement, abnormal shape and entrance, satellite appearance, and vascularloops. These might be due to congenital abnormality of choroid.Conclusion: ICGA could be used to observe the abnormal choroidal vessels.

  3. Femtosecond laser induced breakdown for combustion diagnostics

    International Nuclear Information System (INIS)

    The focused beam of a 100 fs, 800 nm laser is used to induce a spark in some laminar premixed air-methane flames operating with variable fuel content (equivalence ratio). The analysis of the light escaping from the plasma revealed that the Balmer hydrogen lines, Hα and Hβ, and some molecular origin emissions were the most prominent spectral features, while the CN (Β2Σ+-Χ2Σ+) band intensity was found to depend linearly with methane content, suggesting that femtosecond laser induced breakdown spectroscopy can be a useful tool for the in-situ determination and local mapping of fuel content in hydrocarbon-air combustible mixtures.

  4. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references

  5. Laser induced fluorescence of some plant leaves

    International Nuclear Information System (INIS)

    Laser induced fluorescence (LIF) is successfully used as a technique for remote detection of spectral characteristics of some plants. A pulsed nitrogen laser at 337.1 nm is used to excite cotton, corn and rice leaves. The fluorescence spectrum is detected in the range from 340 nm to 820 nm. It is found that, these plant leaves have common fluorescence maxima at 440 nm, 685 nm and 740 nm. plant leaves are also found to be identifiable by the ratio of the fluorescence intensity at 440 nm to that at 685 nm. The present technique can be further used as a means of assessing, remotely, plant stresses. 5 fig

  6. Laser induced surface stress on water droplets.

    Science.gov (United States)

    Wang, Neng; Lin, Zhifang; Ng, Jack

    2014-10-01

    Laser induced stress on spherical water droplets is studied. At mechanical equilibrium, the body stress vanishes therefore we consider only the surface stress. The surface stress on sub-wavelength droplets is slightly weaker along the light propagation direction. For larger droplets, due to their light focusing effect, the forward stress is significantly enhanced. For a particle roughly 3 micron in radius, when it is excited at whispering gallery mode with Q ∼ 10⁴ by a 1 Watt Gaussian beam, the stress can be enhanced by two orders of magnitude, and can be comparable with the Laplace pressure. PMID:25321955

  7. Medical Laser-Induced Thermotherapy - Models and Applications

    OpenAIRE

    Sturesson, Christian

    1998-01-01

    Heat has long been utilised as a therapeutic tool in medicine. Laser-induced thermotherapy aims at achieving the local destruction of lesions, relying on the conversion of the light absorbed by the tissue into heat. In interstitial laser-induced thermotherapy, light is focused into thin optical fibres, which are placed deep into the tumour mass. The objective of this work was to increase the understanding of the physical and biological phenomena governing the response to laser-induced thermot...

  8. Absorption tomography of laser induced plasmas

    International Nuclear Information System (INIS)

    An emission tomography of laser-induced plasmas employed in the laser induced breakdown spectroscopy (LIBS) requires signal integration times in a microsecond range during which the LIBS plasma cannot be considered stationary. Consequently, the use of the data for reconstructing the plasma properties under the assumption that the latter does not change significantly during the integration time leads to inaccurate results. To reduce the integration time, it is proposed to measure a plasma absorption in parallel rays using a scanning rectangular aperture whose dimension Δ along the scanning direction is about a characteristic size of plasma plumes (Δ∼1cm) and the other dimension Δp is of the order of a uniformity length of plasma parameters (Δp∼10μm). The aperture is moved step by step along the scanning direction and the total energy of photons coming through the aperture is measured during time T at each position of the aperture. Owing to the large size of the aperture, the integration time T is reduced by a factor ∼Δp/Δ. A numerical data processing is proposed to restore the spatial resolution of the plasma absorption along the scanning direction. It is determined by the scanning step Δs≤Δp. Another advantage of the proposed procedure is that inexpensive linear CCD or non-discrete (PMT, photodiode) detectors can be used instead of costly 2-dimensional detectors.

  9. CHOROIDAL TUBERCLES IN ISOLATED TUBERCULOUS MENINGITIS

    Directory of Open Access Journals (Sweden)

    Tharun Tom

    2016-04-01

    Full Text Available Choroidal tubercles are the most common manifestation of intraocular tuberculosis and results from the haematogenous spread of mycobacteria in miliary tuberculosis. However, its presence without the evidence of miliary tuberculosis is a rare entity. We present a case of isolated tuberculous meningitis with choroidal tubercles, who had no features of miliary tuberculosis.

  10. A new animal model of choroidal neovascularization

    DEFF Research Database (Denmark)

    Kiilgaard, Jens Folke; Andersen, Mads Varis Nis; Wiencke, Anne;

    2005-01-01

    The purpose of this study was to evaluate the ability of different methods to induce choroidal neovascularization (CNV) in the domestic pig.......The purpose of this study was to evaluate the ability of different methods to induce choroidal neovascularization (CNV) in the domestic pig....

  11. Choroid plexus carcinoma: Report of two cases

    Directory of Open Access Journals (Sweden)

    Singh Avninder

    2009-07-01

    Full Text Available Choroid plexus carcinomas (CPCs are rare malignant counterparts of choroid plexus papilloma which occur in infants and children with a predilection for the posterior fossa and have a poor prognosis. We report two cases of CPC diagnosed in a 5-year-old boy and a 12-year-old boy and discuss the clinicopathologic features.

  12. Choroid plexus cysts. MR and CT findings

    International Nuclear Information System (INIS)

    The MRI and CT characteristics of choroid plexus cysts in the lateral ventricles were investigated. Of eight patients with choroid plexus cysts, six had bilateral and multiple cysts that were small in size, and two patients had unilateral solitary cysts. Choroid plexus cysts were well visualized on T2-WI and proton density-WI with higher signal intensity than the CSF in the lateral ventricles. The walls of cysts were well enhanced with Gd-DTPA. MRI has a distinct advantage over conventional CT for visualization of choroid plexus cysts that are small in size, which may be multiple and bilateral. With the widespread use of MRI, asymptomatic choroid plexus cysts may become common incidental findings. (author)

  13. Anti-VEGF PolysiRNA Polyplex for the Treatment of Choroidal Neovascularization.

    Science.gov (United States)

    Lee, Jihwang; Ryoo, Na-Kyung; Han, Hyounkoo; Hong, Hye Kyoung; Park, Ji Yeon; Park, Sang Jun; Kim, Yong-Kyu; Sim, Changbeom; Kim, Kwangmeyung; Woo, Se Joon; Park, Kyu Hyung; Kim, Hyuncheol

    2016-06-01

    Choroidal neovascularization (CNV) is a major cause of severe vision loss in patients with age-related macular degeneration (AMD). Present ocular siRNA delivery technology is limited due to poor delivery through the retina to the choroid, where CNV originates. Our goal was to develop an optimized nanosized polyRNAi-based therapeutic delivery system to the subretinal space. We developed it by siRNA multimerization (polysiRNA) followed by coating with branched polyethylenimine and hyaluronic acid, and then evaluated its efficacy in vitro and in vivo. The polysiRNA polyplex showed a narrow size distribution (260.7 ± 43.27 nm) and negative charge (-4.98 ± 0.47 mV) owing to the hyaluronic acid outer layer. In vitro uptake of the polysiRNA polyplex by human ARPE cells was discovered, and the direct inhibition of VEGF mRNA translation was confirmed in B16F10 cells. The intravitreally administered polysiRNA polyplex overcame both the vitreous and retina barriers in vivo and reached the subretinal space efficiently. Intravitreal injection of the polysiRNA polyplex was not toxic to the retina in histopathology. Furthermore, intravitreal injections of the polysiRNA polyplex at both 1 and 7 days after laser photocoagulation inhibited laser-induced choroidal neovascularization, compared to that of the control (p < 0.05). These results suggest that anti-VEGF polysiRNA polyplexes show great potential in delivering multimeric RNAi-based therapeutics to treat retinal or choroidal disorders. PMID:27173745

  14. Transscleral sustained vasohibin-1 delivery by a novel device suppressed experimentally-induced choroidal neovascularization.

    Directory of Open Access Journals (Sweden)

    Hideyuki Onami

    Full Text Available We established a sustained vasohibin-1 (a 42-kDa protein, delivery device by a novel method using photopolymerization of a mixture of polyethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and collagen microparticles. We evaluated its effects in a model of rat laser-induced choroidal neovascularization (CNV using a transscleral approach. We used variable concentrations of vasohibin-1 in the devices, and used an enzyme-linked immunosorbent assay and Western blotting to measure the released vasohibin-1 (0.31 nM/day when using the 10 μM vasohibin-1 delivery device [10VDD]. The released vasohibin-1 showed suppression activity comparable to native effects when evaluated using endothelial tube formation. We also used pelletized vasohibin-1 and fluorescein isothiocyanate-labeled 40 kDa dextran as controls. Strong fluorescein staining was observed on the sclera when the device was used for drug delivery, whereas pellet use produced strong staining in the conjunctiva and surrounding tissue, but not on the sclera. Vasohibin-1 was found in the sclera, choroid, retinal pigment epithelium (RPE, and neural retina after device implantation. Stronger immunoreactivity at the RPE and ganglion cell layers was observed than in other retinal regions. Significantly lower fluorescein angiography (FA scores and smaller CNV areas in the flat mounts of RPE-choroid-sclera were observed for the 10VDD, VDD (1 μM vasohibin-1 delivery device, and vasohibin-1 intravitreal direct injection (0.24 μM groups when compared to the pellet, non-vasohibin-1 delivery device, and intravitreal vehicle injection groups. Choroidal neovascularization can be treated with transscleral sustained protein delivery using our novel device. We offer a safer sustained protein release for treatment of retinal disease using the transscleral approach.

  15. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  16. Choroidal Metastases From Cutaneous Melanoma.

    Science.gov (United States)

    Mercado, Carmel L; Toy, Brian C; Kistler, Henry B; Moshfeghi, Darius M

    2016-05-01

    A 92-year-old man presented with months of progressive blurry vision, worsening acutely in his right eye. He denied pain, diplopia, or photopsias. His history was significant for multiple myeloma, prostate cancer, and malignant melanoma of his right shoulder treated with local excision. He had local recurrence with hepatic metastasis of the melanoma treated with radiation and chemotherapy. On examination, his visual acuity was counting fingers in the right eye and 20/60 in the left eye. Amsler grid testing demonstrated metamorphopsia in the right eye. Fundus exam of the right and left eyes revealed multiple, elevated, pigmented choroidal lesions, with associated subretinal fluid in the right macula. This appearance is consistent with hematogenous metastasis of cutaneous malignant melanoma to the choroid and associated serous fluid-causing metamorphopsia. The patient was enrolled in a clinical trial combining plasmid IL-12 with pembrolizumab (Keytruda; Merck, Whitehouse Station, NJ). He passed away 2 months after initial presentation to our clinic. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:497.]. PMID:27183558

  17. The normal choroidal thickness in southern Thailand

    Directory of Open Access Journals (Sweden)

    Jirarattanasopa P

    2014-11-01

    Full Text Available Pichai Jirarattanasopa,1 Nisa Panon,2 Siriphun Hiranyachattada,2 Patama Bhurayanontachai1 1Department of Ophthalmology, Faculty of Medicine, 2Department of Physiology, Faculty of Science, Prince of Songkla University, Hat Yai, Thailand Objective: To investigate the association between subfoveal choroidal thickness in healthy southern Thailand volunteers and age, axial length, and refractive error.Subjects and methods: This was a prospective cross-sectional case series. A total of 210 eyes of 105 healthy volunteers (86 women, age 23–83 years in southern Thailand were examined with enhanced depth-imaging optical coherence tomography. Subjects with systemic diseases that may affect the choroidal vascular blood vessels, such as diabetes, impaired renal function, and hypertension, were excluded. Refractive error and axial length were measured by autorefractometry and an IOLMaster, respectively. Subfoveal choroidal thickness was measured from the outer border of the retinal pigment epithelium to the inner scleral border in the subfoveal area.Results: The mean subfoveal choroidal thickness was 279.4±75.49 µm, and the mean age was 46.4±16.45 years. Subfoveal choroidal thickness was negatively correlated with age (r2=0.33, P<0.0001 and axial length (r2=0.02, P<0.02. Multivariable regression analysis showed subfoveal choroidal thickness was positively and negatively correlated with a spherical equivalent refractive error and axial length, respectively, when adjusted for age.Conclusion: Age is the most important factor in choroidal thickness rather than axial length and refractive error. Subfoval choroidal thickness was decreased 2.67 µm every year and 14.59 µm with 1 mm increase in axial length. Keywords: choroidal thickness, enhanced depth-imaging optical coherence tomography, swept-source optical coherence tomography

  18. Choroidal neovascularization associated with coloboma of the choroid: A series of three cases

    Directory of Open Access Journals (Sweden)

    Bhende Muna

    2011-01-01

    Full Text Available Choroidal neovascularization (CNV is a rare complication associated with coloboma of the choroid. We describe three cases of coloboma choroid where there was loss of vision due to CNV development at the edge of the coloboma. One was managed by photodynamic therapy alone and two were managed by a combination of reduced fluence PDT and intravitreal bevacizumab. Significantly we noted that one treatment session was sufficient to achieve regression of the CNV and improvement in visual acuity.

  19. Choroidal metastasis of a breast carcinoma

    International Nuclear Information System (INIS)

    The case of a 55-year-old woman with diagnosis of multinodular Grade II ductal infiltrating carcinoma in left breast was presented in this article. She presented with temporal visual field defect in her left eye. A choroidal metastatic tumor was diagnosed by indirect binocular ophthalmoscopy, confirmed by ocular echography. The primary tumor was removed by surgery and the choroidal lesion was treated with systemic chemotherapy, hormonal therapy and external beam radiation therapy. Six months after the treatment, the choroidal metastasis showed complete regression, and the best visual acuity of 20/20 was recovered, which was the initial value at the diagnosis of disease

  20. Laser-Induced Damage of Calcium Fluoride

    International Nuclear Information System (INIS)

    Radiation damage of materials has long been of fundamental interest, especially since the growth of laser technology. One such source of damage comes from UV laser light. Laser systems continue to move into shorter wavelength ranges, but unfortunately are limited by the damage threshold of their optical components. For example, semiconductor lithography is making its way into the 157nm range and requires a material that can not only transmit this light (air cannot), but also withstand the highly energetic photons present at this shorter wavelength. CaF2, an alkaline earth halide, is the chosen material for vacuum UV 157 nm excimer radiation. It can transmit light down to 120 nm and is relatively inexpensive. Although it is readily available through natural and synthetic sources, it is often times difficult to find in high purity. Impurities in the crystal can result in occupied states in the band gap that induce photon absorption [2] and ultimately lead to the degradation of the material. In order to predict how well CaF2 will perform under irradiation of short wavelength laser light, one must understand the mechanisms for laser-induced damage. Laser damage is often a two-step process: initial photons create new defects in the lattice and subsequent photons excite these defects. When laser light is incident on a solid surface there is an initial production of electron-hole (e-h) pairs, a heating of free electrons and a generation of local heating around optically absorbing centers [3]. Once this initial excitation converts to the driving energy for nuclear motion, the result is an ejection of atoms, ions and molecules from the surface, known as desorption or ablation [3]. Secondary processes further driving desorption are photoabsorption, successive excitations of self-trapped excitons (STE's) and defects, and ionization of neutrals by incident laser light [3]. The combination of laser-induced desorption and the alterations to the electronic and geometrical

  1. Differential diagnosis of choroidal melanomas and nervi using scanning laser ophthalmoscopical indocyanine green angiography

    DEFF Research Database (Denmark)

    Andersen, Mads V. Nis; Scherfig, Erik; Prause, J.U.

    1995-01-01

    Ophthalmology, choroidal melanoma, choroidal nevus, fluorescein angiography, indocyanine green (ICG), scanning laser ophthalmoscope (SLO), angiography......Ophthalmology, choroidal melanoma, choroidal nevus, fluorescein angiography, indocyanine green (ICG), scanning laser ophthalmoscope (SLO), angiography...

  2. Enucleation versus plaque irradiation for choroidal melanoma

    International Nuclear Information System (INIS)

    The Collaborative Ocular Melanoma Study (COMS) is an international, multicenter-controlled study. The organization includes an Executive Committee, Steering Committee, 6 Central Units, 32 Clinical Centers, and a Data and Safety Monitoring Committee. Scientifically, the COMS consists of (1) a randomized trial of patients with medium choroidal melanoma treated with enucleation versus iodine-125 plaque irradiation, (2) a randomized trial of patients with large choroidal melanoma treated with enucleation versus preenucleation external beam irradiation and enucleation, and (3) a prospective observational study of patients with small choroidal melanoma to determine whether a randomized trial of treatment is appropriate. In design and conduct of the COMS, special consideration is given to biostatistics and sample size considerations, iodine-125 plaque irradiation of choroidal melanoma, and coordinated ocular melanoma research. Recruitment is in progress. However, the pool of eligible patients is limited and the COMS needs the continued support and cooperation of ophthalmologists throughout the United States and Canada

  3. Choroidal physiology and primary angle closure disease.

    Science.gov (United States)

    Zhang, Xiulan; Wang, Wei; Aung, Tin; Jonas, Jost B; Wang, Ningli

    2015-01-01

    Primary angle closure disease (PACD), prevalent in Asian countries, is generally associated with a shallower anterior chamber, a shorter axial length, thicker lens, hyperopia, and female sex. Other physiologic factors, however, may be important, especially with regard to triggering acute primary angle closure. Thickening of the choroid has been demonstrated in untreated and treated, acute and chronic PACD eyes. Recently, there has been growing interest in studying the role of the choroid in the pathophysiology of PACD. The emergence of new imaging technology such as the enhanced depth imaging mode of spectral-domain optical coherence tomography and swept-source optical coherence tomography has contributed to understanding PACD pathologies. We summarize the functions of the choroid and choroidal changes in the pathogenesis of PACD, and discuss potential future developments. PMID:26164737

  4. In Vitro Model of Human Choroidal Neovascular

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Choroidal capillary endothelia cell (CEC) plays a critical role in the development of choroidal neovascularization which is one of the major causes of blindness. An effective method for CEC cultivation was proposed.The isolation of human choroidal CECs using micro dissection followed by the use of superparamagnetic beads (Dynabeads) coated with the CD 31, which selectively binds to the endothelial cell surface. Cells bound to beads were isolated using a magnetic particle concentrator. The CECs were planted into type Ⅳ collagen coated 24 well plates. The results show that the primary cultured CEC is induced to tube formation in collagen Ⅳ coated environment, which can be presented as an in vitro model of choroidal neovascularization.

  5. Choroid plexus carcinoma in an adult

    Directory of Open Access Journals (Sweden)

    Sanjeev Kishore

    2012-01-01

    Full Text Available Choroid plexus carcinoma is a very rare tumor in adults. Here we report a rare case of choroid plexus carcinoma in an adult patient. A 24-year-old male presented with a right temporal intraventricular tumor with a cystic component also extending up to the cortex. Histological examination revealed complex papillary structures and glandular spaces showing stratification and multilayering of cells with nuclear crowding and numerous mitotic figures and large areas of necrosis. The patient went through a complete search for a possible primary keeping in mind the differential diagnosis of metastatic carcinoma that is more common in adults but there was no evidence of any other tumor. Finally a diagnosis of choroid plexus carcinoma was rendered. Immunohistochemical analysis for p53 protein showed positivity. Choroid plexus carcinoma is exceptionally rare in adults but cases do occur.

  6. Choroidal and cutaneous metastasis from gastric adenocarcinoma

    OpenAIRE

    2013-01-01

    Choroidal or cutaneous metastasis of gastric cancer is rare. Gastrointestinal cancer was found in only 4% in patients with uveal metastasis. Choroidal metastasis from gastric cancer was reported in two cases in earlier literature. The frequency of gastric cancer as a primary lesion was 6% in cutaneous metastasis of men, and cutaneous metastasis occurs in 0.8% of all gastric cancers. We report a patient with gastric adenocarcinoma who presented with visual disorder in his left eye and skin pai...

  7. Topical application of a G-Quartet aptamer targeting nucleolin attenuates choroidal neovascularization in a model of age-related macular degeneration.

    Science.gov (United States)

    Leaderer, Derek; Cashman, Siobhan M; Kumar-Singh, Rajendra

    2015-11-01

    Choroidal neovascularization (CNV) associated with the 'wet' form of age related macular degeneration (AMD) is one of the most common causes of central vision loss among the elderly. The 'wet' form of AMD is currently treated by intravitreal delivery of anti-VEGF agents. However, intravitreal injections are associated with complications and long-term inhibition of VEGF leads to macular atrophy. Thus, there is currently an unmet need for the development of therapies for CNV that target molecules other than VEGF. Here, we describe nucleolin as a novel target for the 'wet' form of AMD. Nucleolin was found on the surface of endothelial cells that migrate from the choroid into the subretinal space in the laser-induced model of 'wet' AMD. AS1411 is a previously described G-quartet oligonucleotide that has been shown to bind nucleolin. We found that AS1411 inhibited the formation of tubes by human umbilical vein endothelial cells (HUVECs) by approximately 27.4% in vitro. AS1411 co-localized with the site of laser induced CNV in vivo. Intravitreally injected AS1411 inhibited laser-induced CNV by 37.6% and attenuated infiltration of macrophages by 40.3%. Finally, topical application of AS1411 led to a 43.4% reduction in CNV. Our observations have potential implications for the development of therapies for CNV and specifically for the 'wet' form of AMD. PMID:26368850

  8. Anions in laser-induced plasmas

    Science.gov (United States)

    Shabanov, S. V.; Gornushkin, I. B.

    2016-07-01

    The equation of state for plasmas containing negative atomic and molecular ions (anions) is modeled. The model is based on the assumption that all ionization processes and chemical reactions are at local thermal equilibrium and the Coulomb interaction in the plasma is described by the Debye-Hückel theory. In particular, the equation of state is obtained for plasmas containing the elements Ca, Cl, C, Si, N, and Ar. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules CaCl_2, CaCl, Cl_2, N_2, C_2, Si_2, CN, SiN, SiC, and their positive and negative ions. The model is applied to laser-induced plasmas (LIPs) by including the equation of state into a fluid dynamic numerical model based on the Navier-Stokes equations describing an expansion of LIP plumes into an ambient gas as a reactive viscous flow with radiative losses. In particular, the formation of anions Cl-, C-, Si-, {{Cl}}2^{ - }, {{Si}}2^{ - }, {{C}}2^{ - }, CN-, SiC-, and SiN- in LIPs is investigated in detail.

  9. Laser-induced lipolysis on adipose cells

    Science.gov (United States)

    Solarte, Efrain; Gutierrez, O.; Neira, Rodrigo; Arroyave, J.; Isaza, Carolina; Ramirez, Hugo; Rebolledo, Aldo F.; Criollo, Willian; Ortiz, C.

    2004-10-01

    Recently, a new liposuction technique, using a low-level laser (LLL) device and Ultrawet solution prior to the procedure, demonstrated the movement of fat from the inside to the outside of the adipocyte (Neira et al., 2002). To determine the mechanisms involved, we have performed Scanning and Transmission Electron Microscopy studies; Light transmittance measurements on adipocyte dilutions; and a study of laser light propagation in adipose tissue. This studies show: 1. Cellular membrane alterations. 2. LLL is capable to reach the deep adipose tissue layer, and 3. The tumescence solution enhances the light propagation by clearing the tissue. MRI studies demonstrated the appearance of fat on laser treated abdominal tissue. Besides, adipocytes were cultivated and irradiated to observe the effects on isolated cells. These last studies show: 1. 635 nm-laser alone is capable of mobilizing cholesterol from the cell membrane; this action is enhanced by the presence of adrenaline and lidocaine. 2. Intracellular fat is released from adipocytes by co joint action of adrenaline, aminophyline and 635 nm-laser. Results are consistent with a laser induced cellular process, which causes fat release from the adipocytes into the intercellular space, besides the modification of the cellular membranes.

  10. Laser-induced electron capture mass spectrometry

    Science.gov (United States)

    Wang; Giese

    2000-02-15

    Two techniques are reported for detection of electrophorederivatized compounds by laser-induced electron capture time-of-flight mass spectrometry (LI-EC-TOF-MS). In both cases, a nitrogen laser is used to induce the electron capture. The analyte is deposited in a matrix consisting of a compound with a low ionization potential such as benzo[ghi]perylene in the first technique, where the electron for electron capture apparently comes from this matrix. In the second technique, the analyte is deposited on a silver surface in the absence of matrix. It seems that "monoenergetic" ions instantly desorb from the target surface in the latter case, since the peak width in the continuous extraction mode essentially matches the pulse width of the laser (4 ns). Ten picomoles of 3-O-(pentafluorobenzyl)-alpha-estradiol were detected at a S/N > or = 50, where the spot size of the laser was approximately 0.25% of the sample spot. It is attractive that simple conditions can enable sensitive detection of electrophores on routine TOF-MS equipment. The technique can be anticipated to broaden the range of analytes in both polarity and size that can be detected by EC-MS relative to the range for GC/EC-MS. PMID:10701262

  11. Laser induced fluorescence spectroscopy for FTU

    International Nuclear Information System (INIS)

    Laser induced fluorescence spectroscopy (LIFS) is based on the absorption of a short pulse of tuned laser light by a group of atoms and the observation of the resulting fluorescence radiation from the excited state. Because the excitation is resonant it is very efficient, and the fluorescence can be many times brighter than the normal spontaneous emission, so low number densities of the selected atoms can be detected and measured. Good spatial resolution can be achieved by using a narrow laser beam. If the laser is sufficiently monochromatic, and it can be tuned over the absorption line profile of the selected atoms, information can also be obtained about the velocities of the atoms from the Doppler effect which can broaden and shift the line. In this report two topics are examined in detail. The first is the effect of high laser irradiance, which can cause 'power broadening' of the apparent absorption line profile. The second is the effect of the high magnetic field in FTU. Detailed calculations are given for LIFS of neutral iron and molybdenum atoms, including the Zeeman effect, and the implementation of LIFS for these atoms on FTU is discussed

  12. Medical Applications of Laser Induced Breakdown Spectroscopy

    International Nuclear Information System (INIS)

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail

  13. Medical Applications of Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Pathak, A. K.; Rai, N. K.; Singh, Ankita; Rai, A. K.; Rai, Pradeep K.; Rai, Pramod K.

    2014-11-01

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail.

  14. Laser Induced Birefringence in Pure Liquids

    Science.gov (United States)

    Harrison, Neil J.

    1991-01-01

    Available from UMI in association with The British Library. Laser induced birefringence or the Optical Kerr effect is a subject that has undergone much research over previous years and is an established technique for the study of many classes of materials. To date the measurements on various media have been characterized by the substantial time required to obtain results and the generally poor sensitivity of the apparatus used. This work describes the development of a new apparatus which is the first in the field to automate the signal capture and analysis utilizing a 1 Gigasample/second digitizing oscilloscope connected to a microcomputer to provide fast, accurate transient analysis. Careful design of the apparatus enabled operation at two inducing wavelengths of 532nm and 1064nm. The sensitivity and accuracy of the apparatus coupled with the rapid transient evaluation was tested on a number of well characterized samples including benzene, nitrobenzene, toluene and benzoyl chloride and was found to give excellent agreement with other workers. The apparatus was used to investigate the properties of the organic pure liquid series the n-alkanes before making the first measurements on the 1-alkenes, 1-alkynes, alcohols, carboxylic acids and three alkdienes. Results from these experiments were used to evaluate the contributions of sigma and pi bonds to the Optical Kerr effect in simple organic molecules. A review of all previously published Optical Kerr effect results for pure liquids was also carried out and the first comprehensive table of results complied.

  15. Volume of a laser-induced microjet

    Science.gov (United States)

    Kawamoto, Sennosuke; Hayasaka, Keisuke; Noguchi, Yuto; Tagawa, Yoshiyuki

    2015-11-01

    Needle-free injection systems are of great importance for medical treatments. In spite of their great potential, these systems are not commonly used. One of the common problems is strong pain caused by diffusion shape of the jet. To solve this problem, the usage of a high-speed highly-focused microjet as needle-free injection system is expected. It is thus crucial to control important indicators such as ejected volume of the jet for its safe application. We conduct experiments to reveal which parameter influences mostly the ejected volume. In the experiments, we use a glass tube of an inner diameter of 500 micro-meter, which is filled with the liquid. One end is connected to a syringe and the other end is opened. Radiating the pulse laser instantaneously vapors the liquid, followed by the generation of a shockwave. We find that the maximum volume of a laser-induced bubble is approximately proportional to the ejected volume. It is also found that the occurrence of cavitation does not affect the ejected volume while it changes the jet velocity.

  16. Laser Induced Fluorescence of the Iodine Ion

    Science.gov (United States)

    Hargus, William

    2014-10-01

    Iodine (I2) has been considered as a potential electrostatic spacecraft thruster propellant for approximately 2 decades, but has only recently been demonstrated. Energy conversion efficiency appears to be on par with xenon without thruster modification. Intriguingly, performance appears to exceed xenon at high acceleration potentials. As part of a continuing program for the development of non-intrusive plasma diagnostics for advanced plasma spacecraft propulsion, we have identified the I II 5d5D4 o state as metastable, and therefore containing a reservoir of excited state ions suitable for laser probing. The 5d5D4 o - 6p5P3 transition at 695.878 nm is convenient for diode laser excitation with the 5s5S2 o - 6p5P3 transition at 516.12 nm as an ideal candidate for non-resonant fluorescence collection. We have constructed a Penning type iodine microwave discharge lamp optimized for I II production for table-top measurements. This work demonstrates I II laser-induced fluorescence in a representative iodine discharge and will validate our previous theoretical work based on the limited available historical I II spectral data.

  17. Laser-induced fluorescence in medical diagnostics

    Science.gov (United States)

    Andersson-Engels, Stefan; Johansson, Jonas; Svanberg, Katarina; Svanberg, Sune

    1990-07-01

    We have performed extensive investigations using laser-induced fluorescence in animal as well as human tissue in order to localize diseased tissue and thus discriminate such tissue from normal surrounding areas. In characterizing different tissue types the endogenous fluorescence (autofluorescence) as well as specific fluorescence from different photosensitising substances was utilized. We have investigated different experimental and human malignant tumors in vivo and in vitro as well as atherosclerotic lesions in vitro. A fiber-optic fluorosensor was constructed and used in the experiments and in the clinical examination of patients. Dimensionless spectroscopic functions were formed to ensure that the signals were independent of clinically uncontrollable variables such as distance variations, tissue topography, light source fluctuations and variations in detection efficiency. A multi-color two-dimensional imaging system was constructed for real-time imaging. The system was tested peroperatively and during standard examination patient procedures. Besides utilizing the time-integrated fluorescence signal we have also investigated the possibility of incorporating time-resolved fluorescence characterization.

  18. Femtosecond Laser Induced Underwater Superoleophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Yong Jiale

    2015-01-01

    Full Text Available Femtosecond laser microfabrication has been recently utilized in interface science to modify the liquid wettability of solid surfaces. Silicon surface with hierarchical micro/nanostructure is fabricated by a femtosecond laser. Similar to the fish’s scales, the laser-induced surface shows superhydrophilicity in air and superoleophobicity underwater. The oil contact angles can reach up to 159.4 ± 1° for the 1,2-dichloroethane droplets in water. Besides, the surface exhibits ultralow oil-adhesion. In the oil/water/solid three-phase system, water can be trapped in the hierarchical rough structure and forms a repulsive oil layer according to underwater Cassie’s theory. The contact area between the asprepared surface and oil droplet is significantly reduced, resulting in superoleophobicity and ultralow oil-adhesion in water. In addition, transparent underwater superoleophobic and anti-oil surfaces are achieved on silica glass surfaces by femtosecond laser ablation. This transparent property is attributed to the presence of the water environment because scattering and refraction are effectively weakened. The presented method is simple and can accurately control the processing location, which may have widely potential applications in, for instance, microfluidics, biotechnologies, and antifouling coatings.

  19. Laser-Induced Magnetic Dipole Spectroscopy.

    Science.gov (United States)

    Hintze, Christian; Bücker, Dennis; Domingo Köhler, Silvia; Jeschke, Gunnar; Drescher, Malte

    2016-06-16

    Pulse electron paramagnetic resonance measurements of nanometer scale distance distributions have proven highly effective in structural studies. They exploit the magnetic dipole-dipole coupling between spin labels site-specifically attached to macromolecules. The most commonly applied technique is double electron-electron resonance (DEER, also called pulsed electron double resonance (PELDOR)). Here we present the new technique of laser-induced magnetic dipole (LaserIMD) spectroscopy based on optical switching of the dipole-dipole coupling. In a proof of concept experiment on a model peptide, we find, already at a low quantum yield of triplet excitation, the same sensitivity for measuring the distance between a porphyrin and a nitroxide label as in a DEER measurement between two nitroxide labels. On the heme protein cytochrome C, we demonstrate that LaserIMD allows for distance measurements between a heme prosthetic group and a nitroxide label, although the heme triplet state is not directly observable by an electron spin echo. PMID:27163749

  20. Vacuum ultraviolet laser induced fluorescence on a Si atomic beam

    Science.gov (United States)

    O'Brian, T. R.; Lawler, J. E.

    1991-01-01

    A broadly applicable vacuum ultraviolet experiment is described for measuring radiative lifetimes of neutral and singly-ionized atoms in a beam environment to 5-percent accuracy using laser induced fluorescence. First results for neutral Si are reported.

  1. Comparision of laser-induced and classical ultasound

    Science.gov (United States)

    Niederhauser, Joel J.; Jaeger, Michael; Frenz, Martin

    2003-06-01

    A classical medical ultrasound system was combined with a pulsed laser source to allow laser-induced ultrasound imaging (optoacoustics). Classical ultrasound is based on reflection and scattering of an incident acoustic pulse at internal tissue structures. Laser-induced ultrasound is generated in situ by heating optical absorbing structures, such as blood vessels, with a 5 ns laser pulse (few degrees or fraction of degree), which generates pressure transients. Laser-induced ultrasound probes optical properties and therefore provides much higher contrast and complementary information compared to classical ultrasound. An ultrasound array transducer in combination with a commercial medical imaging system was used to record acoustic transients of both methods. Veins and arteries in a human forearm were identified in vivo using classical color doppler and oxygenation dependent optical absorption at 660 nm and 1064 nm laser wavelength. Safety limits of both methods were explored. Laser-induced ultrasound seems well suited to improve classical ultrasound imaging of subcutaneous regions.

  2. Compact High Sensitive Laser-Induced Breakdown Spectroscopy Instrument Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser induced breakdown spectroscopy (LIBS) is a versatile tool for in situ substance characterization. Existing LIBS instruments are not compact enough for space...

  3. Shot noise limited detection of OH using the technique of laser induced fluorescence

    International Nuclear Information System (INIS)

    Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluorescence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the shot-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements

  4. Laser-induced contamination on high-reflective optics

    OpenAIRE

    Wagner, Paul

    2014-01-01

    Operating high power space-based laser systems in the visible and UV range is problematic due to laser-induced contamination. Organic materials are outgassing in vacuum and deposit on irradiated optical components. To provide reliable space-based laser systems the optical components quality plays a major role. In this thesis laser-induced contamination growth on high-reflective coated optics is investigated for UV irradiation of 355nm with naphthalene as contamination material. Four different...

  5. Laser-induced damage of multilayer coated optical components

    International Nuclear Information System (INIS)

    A number of optics having high quality and high damage threshold were developed. The damage threshold of borosilicate crown glass has been considerably improved. The surface roughness dependence of the laser-induced surface damage of optical glasses and the laser-induced damage of high resolution coating were found for the first time. These optical technologies meet the GEKKO XII Upgrade fluence requirements. (author)

  6. Laser-induced damage of multilayer coated optical components

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Kunio (Osaka Inst. of Tech. (Japan)); Yoshida, Hidetsugu; Nakatsuka, Masahiro; Jitsuno, Takahisa; Namba, Yoshiharu; Sasaki, Takatomo; Kanabe, Tadashi; Yamanaka, Tatsuhiko; Nakai, Sadao

    1992-11-01

    A number of optics having high quality and high damage threshold were developed. The damage threshold of borosilicate crown glass has been considerably improved. The surface roughness dependence of the laser-induced surface damage of optical glasses and the laser-induced damage of high resolution coating were found for the first time. These optical technologies meet the GEKKO XII Upgrade fluence requirements. (author).

  7. Q-Switched Alexandrite Laser-induced Chrysiasis

    OpenAIRE

    Cohen, Philip R; Victor Ross, E.

    2015-01-01

    Background: Chyriasis is an uncommon side effect that occurs in patients who are receiving prolonged treatment with either intravenous or intramuscular gold as a distinctive blue-gray pigmentation of light-exposed skin. Laser-induced chrysiasis is a rarely described phenomenon in individuals who have received systemic gold and are subsequently treated with a Q-switched laser. Purpose: To describe the characteristics of patients with laser-induced chrysiasis. Methods: The authors describe a 60...

  8. Laser-induced fluorescence for medical diagnostics

    International Nuclear Information System (INIS)

    Laser-induced fluorescence as a tool for tissue diagnostics is discussed. Both spectrally and time-resolved fluorescence signals are studied to optimize the demarcation of diseased lesions from normal tissue. The presentation is focused on two fields of application: the identification of malignant tumours and atherosclerotic plaques. Tissue autofluorescence as well as fluorescence from administered drugs have been utilized in diseased tissue diagnosis. The fluorescence criterion for tissue diagnosis is, as far as possible, chosen to be independent of unknown fluorescence parameters, which are not correlated to the type of tissue investigated. Both a dependence on biological parameters, such as light absorption in blood, and instrumental characteristics, such as excitation pulse fluctuations and detection geometry, can be minimized. Several chemical compounds have been studied in animal experiments after intraveneous injection to verify their capacity as malignant tumour marking drugs under laser excitation and fluorescence detection. Another objective of these studies was to improve our understanding of the mechanism and chemistry behind the retention of the various drugs in tissue. The properties of a chemical which maximize its selective retention in tumours are discussed. In order to utilize this diagnostic modality, three different clinically adapted sets of instrumentation have been developed and are presented. Two of the systems are nitrogen-laser-based fluorosensors; one is a point-monitoring system with full spectral resolution and the other one is an imaging system with up to four simultaneously recorded images in different spectral bands. The third system is a low-cost point-monitoring mercury-lamp-based fluoroscence emission as well as reflection characteristics of tissue. (author)

  9. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  10. Genetics Home Reference: gyrate atrophy of the choroid and retina

    Science.gov (United States)

    ... the choroid. During childhood, they begin experiencing nearsightedness ( myopia ), difficulty seeing in low light (night blindness), and ... the choroid and retina in a child with myopia. Indian Pediatr. 2001 Aug;38(8):914-8. ...

  11. Subretinal lipid exudation associated with untreated choroidal melanoma

    Directory of Open Access Journals (Sweden)

    C K Minija

    2011-01-01

    Full Text Available Subretinal lipid exudation in an untreated choroidal melanoma is very rare. It is seen following plaque radiotherapy in choroidal melanoma. There is only one case report of untreated choroidal melanoma with massive lipid exudation in a patient with metastatic hypernephroma. We report here a rare case of untreated choroidal melanoma with lipid exudation. Subretinal exudation that is rarely seen following plaque brachytherapy was noted at the borders of this untreated tumor. Lipid exudation partially resolved following brachytherapy.

  12. Inhibition of RACK1 ameliorates choroidal neovascularization formation in vitro and in vivo.

    Science.gov (United States)

    Liu, Xiaojuan; Zhu, Manhui; Yang, Xiaowei; Wang, Ying; Qin, Bai; Cui, Chen; Chen, Hui; Sang, Aimin

    2016-06-01

    Choroidal neovascularization (CNV) occurs as a result of age-related macular degeneration (AMD) and causes severe vision loss among elderly patients. The receptor for activated C-kinase 1 (RACK1) serves as a scaffold protein which is recently found to promote angiogenesis. However, the impact of RACK1 on the vascular endothelial growth factor (VEGF) expression in endothelial cells and subsequent choroidal angiogenesis formation remains to be elucidated. In this study, we found that RACK1 and VEGF expression increased, and reached the peak at 7d in mouse CNV model by laser application. Furthermore, on RPE/choroid cryosections, RACK1 co-localized with CD31, suggesting that RACK1 was expressed in endothelial cells. In vitro, RF/6A cell hypoxia model showed that RACK1 expression was up-regulated in parallel with hypoxia-induced factor 1 (HIF-1α) and VEGF expression, reaching the peak at 6h. Silencing of RACK1 suppressed the invasion and tube formation activity of RF/6A cells in ARPE-19 and RF/6A co-culture system, possibly through VEGF signal pathway. Overexpression of RACK1 showed the opposite effect. Intravitreal injection of anti-RACK1 monoclonal antibody predominantly decreased RACK1 and VEGF expression in mouse laser-induced CNV model. Meanwhile, anti-RACK1 monoclonal antibody intravitreal injection also decreased incidence of CNV and leakage area. These data indicated that RACK1 promoted CNV formation via VEGF pathway. Additionally, anti-RACK1 monoclonal antibody significantly decreased CNV in mouse model and may have therapeutic potential in human CNV. PMID:27112838

  13. Modifying Choroidal Neovascularization Development with a Nutritional Supplement in Mice

    Directory of Open Access Journals (Sweden)

    Alina Adriana Ivanescu

    2015-07-01

    Full Text Available We examined the effect of nutritional supplements (modified Age Related Eye Disease Study (AREDS-II formulation containing vitamins, minerals, lutein, resveratrol, and omega-3 fatty acids on choroidal neovascularization (CNV. Supplements were administered alone and combined with intravitreal anti-VEGF in an early-CNV (diode laser-induced murine model. Sixty mice were evenly divided into group V (oral vehicle, intravitreal saline, group S (oral supplement, intravitreal saline, group V + aVEGF (oral vehicle, intravitreal anti-VEGF, and group S + aVEGF (oral supplement, intravitreal anti-VEGF. Vehicle and nutritional supplements were administered daily for 38 days beginning 10 days before laser. Intravitreal injections were administered 48 h after laser. Fluorescein angiography (FA and flat-mount CD31 staining evaluated leakage and CNV lesion area. Expression of VEGF, MMP-2 and MMP-9 activity, and NLRP3 were evaluated with RT-PCR, zymography, and western-blot. Leakage, CNV size, VEGF gene and protein expression were lower in groups V + aVEGF, S + aVEGF, and S than in V (all p < 0.05. Additionally, MMP-9 gene expression differed between groups S + aVEGF and V (p < 0.05 and MMP-9 activity was lower in S + aVEGF than in V and S (both p < 0.01. Levels of MMP-2 and NLRP3 were not significantly different between groups. Nutritional supplements either alone or combined with anti-VEGF may mitigate CNV development and inhibit retinal disease involving VEGF overexpression and CNV.

  14. Modifying Choroidal Neovascularization Development with a Nutritional Supplement in Mice.

    Science.gov (United States)

    Ivanescu, Alina Adriana; Fernández-Robredo, Patricia; Heras-Mulero, Henar; Sádaba-Echarri, Luis Manuel; García-García, Laura; Fernández-García, Vanessa; Moreno-Orduna, Maite; Redondo-Exposito, Aitor; Recalde, Sergio; García-Layana, Alfredo

    2015-07-01

    We examined the effect of nutritional supplements (modified Age Related Eye Disease Study (AREDS)-II formulation containing vitamins, minerals, lutein, resveratrol, and omega-3 fatty acids) on choroidal neovascularization (CNV). Supplements were administered alone and combined with intravitreal anti-VEGF in an early-CNV (diode laser-induced) murine model. Sixty mice were evenly divided into group V (oral vehicle, intravitreal saline), group S (oral supplement, intravitreal saline), group V + aVEGF (oral vehicle, intravitreal anti-VEGF), and group S + aVEGF (oral supplement, intravitreal anti-VEGF). Vehicle and nutritional supplements were administered daily for 38 days beginning 10 days before laser. Intravitreal injections were administered 48 h after laser. Fluorescein angiography (FA) and flat-mount CD31 staining evaluated leakage and CNV lesion area. Expression of VEGF, MMP-2 and MMP-9 activity, and NLRP3 were evaluated with RT-PCR, zymography, and western-blot. Leakage, CNV size, VEGF gene and protein expression were lower in groups V + aVEGF, S + aVEGF, and S than in V (all p < 0.05). Additionally, MMP-9 gene expression differed between groups S + aVEGF and V (p < 0.05) and MMP-9 activity was lower in S + aVEGF than in V and S (both p < 0.01). Levels of MMP-2 and NLRP3 were not significantly different between groups. Nutritional supplements either alone or combined with anti-VEGF may mitigate CNV development and inhibit retinal disease involving VEGF overexpression and CNV. PMID:26153682

  15. Combination therapy of low-fluence photodynamic therapy and intravitreal ranibizumab for choroidal neovascular membrane in choroidal osteoma

    OpenAIRE

    Morris, Rodney J; Prabhu, Varsha V; Parag K Shah; Narendran, V.

    2011-01-01

    Choroidal osteoma is an unusual form of intraocular calcification seen in otherwise healthy eyes. It is a benign idiopathic osseous tumor of the choroid, typically seen in young females. Choroidal neovascular membrane (CNVM) is a complication seen in one-third of these patients and carries a poor visual outcome. We report a case of a 25-year-old hyperthyroid female with choroidal osteoma and subfoveal CNVM in her left eye which was successfully treated using low-fluence photodynamic therapy (...

  16. Laser-Induced-Fluorescence Photogrammetry and Videogrammetry

    Science.gov (United States)

    Danehy, Paul; Jones, Tom; Connell, John; Belvin, Keith; Watson, Kent

    2004-01-01

    surface of the target. The improved method is denoted laser-induced-fluorescence photogrammetry.

  17. Intravitreal bevacizumab (avastin for circumscribed choroidal hemangioma

    Directory of Open Access Journals (Sweden)

    Subrata Mandal

    2011-01-01

    Full Text Available Circumscribed choroidal hemangiomas are rare ophthalmic entities that cause diminution in vision due to accumulation of subretinal and/or intraretinal fluid in the macular area. Various treatment options ranging from conventional laser to photodynamic therapy have been employed to destroy the tumor and reduce the exudation; however, either the inability to penetrate through the exudative fluid or the collateral retinal damage induced by these treatment modalities make them unsuitable for lesions within the macula. We evaluated the role of intravitreal bevacizumab, a pan-vascular endothelial growth factor (VEGF inhibitor, in reducing the sub- and intraretinal fluid in three patients with circumscribed choroidal hemangiomas. All the patients had complete resolution of the serous retinal detachment that was maintained till at least 12 months after the first injection. Intravitreal bevacizumab may be used in combination with thermal laser or photodynamic therapy in treating circumscribed choroidal hemangiomas with subretinal fluid.

  18. Retinal Inhibition of CCR3 Induces Retinal Cell Death in a Murine Model of Choroidal Neovascularization.

    Science.gov (United States)

    Wang, Haibo; Han, Xiaokun; Gambhir, Deeksha; Becker, Silke; Kunz, Eric; Liu, Angelina Jingtong; Hartnett, M Elizabeth

    2016-01-01

    Inhibition of chemokine C-C motif receptor 3 (CCR3) signaling has been considered as treatment for neovascular age-related macular degeneration (AMD). However, CCR3 is expressed in neural retina from aged human donor eyes. Therefore, broad CCR3 inhibition may be harmful to the retina. We assessed the effects of CCR3 inhibition on retina and choroidal endothelial cells (CECs) that develop into choroidal neovascularization (CNV). In adult murine eyes, CCR3 colocalized with glutamine-synthetase labeled Műller cells. In a murine laser-induced CNV model, CCR3 immunolocalized not only to lectin-stained cells in CNV lesions but also to the retina. Compared to non-lasered controls, CCR3 mRNA was significantly increased in laser-treated retina. An intravitreal injection of a CCR3 inhibitor (CCR3i) significantly reduced CNV compared to DMSO or PBS controls. Both CCR3i and a neutralizing antibody to CCR3 increased TUNEL+ retinal cells overlying CNV, compared to controls. There was no difference in cleaved caspase-3 in laser-induced CNV lesions or in overlying retina between CCR3i- or control-treated eyes. Following CCR3i, apoptotic inducible factor (AIF) was significantly increased and anti-apoptotic factor BCL2 decreased in the retina; there were no differences in retinal vascular endothelial growth factor (VEGF). In cultured human Műller cells exposed to eotaxin (CCL11) and VEGF, CCR3i significantly increased TUNEL+ cells and AIF but decreased BCL2 and brain derived neurotrophic factor, without affecting caspase-3 activity or VEGF. CCR3i significantly decreased AIF in RPE/choroids and immunostaining of phosphorylated VEGF receptor 2 (p-VEGFR2) in CNV with a trend toward reduced VEGF. In cultured CECs treated with CCL11 and/or VEGF, CCR3i decreased p-VEGFR2 and increased BCL2 without increasing TUNEL+ cells and AIF. These findings suggest that inhibition of retinal CCR3 causes retinal cell death and that targeted inhibition of CCR3 in CECs may be a safer if CCR3 inhibition

  19. Long-term outcomes of intravitreal injection of bevacizumab for choroidal neovascularization associated with choroidal osteoma

    OpenAIRE

    Yoshikawa T; Takahashi K.

    2015-01-01

    Tadanobu Yoshikawa, Kanji Takahashi Department of Ophthalmology, Kansai Medical University, Osaka, Japan Purpose: To describe the outcomes of intravitreal injections of bevacizumab for choroidal neovascularization (CNV) associated with choroidal osteoma. Methods: Retrospective consecutive case series. Three eyes of three patients were studied. All patients were treated with intravitreal injections of bevacizumab for CNV associated with choroidal osteoma. Best-corrected visual acuity, centra...

  20. Long-term outcomes of intravitreal injection of bevacizumab for choroidal neovascularization associated with choroidal osteoma

    OpenAIRE

    Yoshikawa, Tadanobu

    2015-01-01

    Tadanobu Yoshikawa, Kanji Takahashi Department of Ophthalmology, Kansai Medical University, Osaka, Japan Purpose: To describe the outcomes of intravitreal injections of bevacizumab for choroidal neovascularization (CNV) associated with choroidal osteoma. Methods: Retrospective consecutive case series. Three eyes of three patients were studied. All patients were treated with intravitreal injections of bevacizumab for CNV associated with choroidal osteoma. Best-corrected visual acuity, centra...

  1. Laser induced incandescence and laser induced breakdown spectroscopy based sensor development

    Science.gov (United States)

    Eseller, Kemal Efe

    In this doctoral dissertation, two laser-based sensors were evaluated for different applications. Laser Induced Incandescence (LII) is a technique which can provide non-intrusive quantitative measurement of soot and it provides a unique diagnostic tool to characterize engine performance. Since LII is linearly proportional to the soot volume fraction, it can provide in situ, real time measurement of soot volume fraction with high temporal and spatial resolution. LII has the capability to characterize soot formation during combustion. The soot volume fraction from both flames and a soot generator was investigated with LII. The effects of experimental parameters, such as laser fluence, gate delay, gate width and various laser beam focusing, on LII signal was studied. Laser Induced Breakdown Spectroscopy (LIBS), a diagnostic tool for in situ elemental analysis, has been evaluated for on-line, simultaneous, multi-species impurity monitoring in hydrogen. LIBS spectra with different impurity levels of nitrogen, argon, and oxygen were recorded and the intensity of the spectral lines of Ar, O, N, and H observed were used to form calibration plots for impurities in hydrogen measurements. An ungated detection method for LIBS has been developed and applied to equivalence ratio measurements of CH4/air and biofuel/air. LIBS has also been used to quantitatively analyze the composition of a slurry sample. The quenching effect of water in slurry samples causes low LIBS signal quality with poor sensitivity. Univariate and multivariate calibration was performed on LIBS spectra of dried slurry samples for elemental analysis of Mg, Si and Fe. Calibration results show that the dried slurry samples give good correlation between spectral intensity and elemental concentration.

  2. Laser-induced breakdown spectroscopy analysis of asbestos

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy was applied to test the possibility of detecting and identifying asbestos in different samples in view of the perspective at field operation without sample preparation which is peculiar to this technique. Several like-resin materials were first investigated by laser-induced breakdown spectroscopy, in order to find an asbestos container assuring safe laboratory operation during the material characterization aimed to identify indicators suitable for a quick identification on field. Successively, spectra of asbestos samples of both in serpentine and amphibole forms were measured and the variability in elemental composition was calculated from the emission spectra. Ratios of intensities of characteristic elements were tested as indicators for asbestos recognition. Laser-induced breakdown spectroscopy results were compared with those obtained by analyzing the same asbestos samples with a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, a good correlation was found for Mg/Si and Fe/Si, thus showing the capability of laser-induced breakdown spectroscopy as a diagnostic tool for this category of materials. In particular, it was demonstrated that the method based on two indicators derived from laser-induced breakdown spectroscopy intensity ratios allows to discriminate between asbestos and cements in single shot measurements suitable to field operation

  3. Choroidal Tuberculoma in an Immunocompetent Young Patient

    Institute of Scientific and Technical Information of China (English)

    Xiu-fen Yang; Jun Xu; Kai Ma

    2011-01-01

    @@ TUBERCULOSIS (TB) remains one of the leading causes of preventable morbidity and mortality from infectious disease worldwide.1 It is a chronic progressive granulomatous infection caused by Mycobacterium tuberculosis (M.tuberculosis).Ocular involvement in patients with systemic TB has traditionally been considered uncommon.The incidence of ocular TB was reported to be 1.46% among 10 524 patients in a TB sanatorium2 and there are only few reports of choroidal tuberculoma in the literature .3-5 Here we reported a case of choroidal tuberculoma in an immunocompetent young patient with a history of tuberculous pleurisy.

  4. Anisotropy of Laser-Induced Bulk Damage of Single Crystals

    OpenAIRE

    Krupych, O.; Dyachok, Ya.; Smaga, I.; Vlokh, R.

    2007-01-01

    The regularities of laser-induced damage of anisotropic materials, such as LiNbO3 and KDP dielectric single crystals, are experimentally studied. It is revealed that the shape of laser-induced damage in the dielectric crystals depends on the elastic symmetry of crystal and the propagation direction of the laser beam. When the beam propagates along the optic axis of crystals, the figures of the laser damage are six-path stars for LiNbO3 and four-path ones for KDP crystals. For the direction pa...

  5. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

    A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self-diffracti......A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self...

  6. Laser induced breakdown spectroscopy stratigraphic characterization of multilayered painted surfaces

    Science.gov (United States)

    Staicu, A.; Apostol, I.; Pascu, A.; Iordache, I.; Damian, V.; Pascu, M. L.

    2012-08-01

    Laser spectroscopy techniques are modern and competitive methods for elemental analysis. Laser induced breakdown spectroscopy (LIBS), due to its advantages as minimally invasive method that provides real time monitoring and selectivity, is a suitable tool to analyze sample composition. Based on the known emission spectra of heavy metals such as Pb, Zn, Au, Ca, a stratigraphic study regarding the identification of the painting layers content of different mock-up samples was performed. LIBS was used to monitor the laser induced stepwise selective removal of the painting layers and to analyze their composition. The obtained LIBS spectra were correlated with profilometric measurements.

  7. Infantile myofibromatosis involving the choroid plexus

    International Nuclear Information System (INIS)

    We present a case of infantile myofibromatosis manifest as a choroid plexus mass followed by spontaneous regression. Infantile myofibromatosis is a common juvenile fibrous disorder occurring in infancy and early childhood. Intracranial involvement in infantile myofibromatosis is rare. It generally occurs in the dura with calvarial invasion and secondary brain compression. (orig.)

  8. Photodynamic therapy of symptomatic choroidal nevi

    Directory of Open Access Journals (Sweden)

    Luis Amselem

    2011-01-01

    Full Text Available Purpose : To evaluate the role of photodynamic therapy (PDT for patients with symptomatic choroidal nevi involving the fovea or located near the fovea with subretinal fluid extending to the fovea. Materials and Methods : Retrospective review of five patients who underwent PDT for choroidal nevi at two separate centers in Ankara and Barcelona. Results : The mean initial logMAR visual acuity was 0.5 (range: 0 to 1.5. The mean largest tumor base diameter was 3.2 mm (range: 2.1-4.5 mm and the mean tumor thickness was 1.1 mm (range: 0.7-1.6 mm. The mean number of PDT sessions was 1.6 (range:1-3. The mean final tumor thickness was 1.0 mm (range: 0-1.6 mm at a mean follow-up of 19 months (range: 12-32 months. The mean final logMAR visual acuity was 0.4 (range: 0-1.5. Subfoveal fluid disappeared or decreased significantly in 4 of 5 eyes (80% after PDT. Conclusions : PDT led to resolution of subretinal fluid with preservation of visual acuity in many symptomatic choroidal nevi in this study. Careful case selection is important as PDT of indeterminate pigmented tumors may delay the diagnosis and treatment of an early choroidal melanoma and thereby increase the risk for metastasis.

  9. Cerebellopontine Choroid Plexus Papilloma: Case Report

    International Nuclear Information System (INIS)

    We present the case of an adult female patient who presented with a mass in the cerebellopontine angle, corresponding to a choroid plexus papilloma. Due to this uncommon location, we report this case and describe its imaging characteristics and the possible differential diagnoses.

  10. Primary transpupillary thermotherapy of choroidal melanocytic lesions

    Directory of Open Access Journals (Sweden)

    Kaan Gündüz

    2011-01-01

    Full Text Available Purpose : To evaluate the role of primary transpupillary thermotherapy (TTT in the treatment of choroidal melanocytic lesions. Materials and Methods : Retrospective chart review of 24 patients (24 eyes with choroidal melanocytic lesions, including 20 choroidal melanoma and four choroidal nevus treated with primary TTT. Choroidal nevus cases treated with primary TTT either demonstrated risk factors for growth into an early melanoma or had overlying choroidal neovascularization. Results : The mean initial tumor basal diameter was 6.6 (3.0-10.0 mm and the mean initial tumor thickness was 3.0 (1.0-5.0 mm. The mean number of TTT sessions was 2.5 (1-6. The mean decrease in tumor thickness was 1.2 mm (from 3.0 to 1.8 mm at a mean follow-up of 22.7 (range 3-90 months. On the LogMar scale, visual acuity was stable at 1.0. Complications occurred in 50% of eyes. The most frequent complications were vitreous hemorrhage [5 patients (20.8%], focal cataract [5 patients (20.8%], iris atrophy [4 patients (16.6%] and posterior synechia [4 patients (16.6%]. There was no significant difference in the complication rate with respect to tumor thickness >3 mm versus tumor thickness ≤3 mm and juxtapapillary versus nonjuxtapapillary location (Fisher′s exact test, P>0.05. Kaplan-Meier curves showed that 9% of eyes develop recurrence by 1 year and 27% develop recurrence by 5 years after primary TTT. Two eyes (8.3% were enucleated because of neovascular glaucoma and one eye (4.1% was exenterated because of extraocular tumor recurrence. Globe salvage was achieved in 21 patients (87.5%. One patient (4.1% with extraocular tumor recurrence developed liver metastasis and expired. Conclusions : Although TTT may be useful in the treatment of small choroidal melanocytic lesions, the high complication and recurrence rates warrant close monitoring of patients after primary TTT even when a flat chorioretinal scar has been achieved.

  11. Holographic schlieren investigation of laser-induced plasmas

    International Nuclear Information System (INIS)

    Quantitative holographic schlieren studies of a CO2 laser induced breakdown in argon have been made using a pulsed ruby laser. Complete mappings of the density gradient profiles at different temporal stages of the plasma are obtained. The density gradients are integrated to obtain density profiles which compare well with those obtained directly by holographic interferometry. (Auth.)

  12. Laser-induced periodic surface structures, modeling, experiments, and applications

    NARCIS (Netherlands)

    Römer, G.R.B.E.; Skolski, J.Z.P.; Vincenc Obona, J.; Ocelik, V.; Hosson, de J.Th.M.; Huis in 't Veld, A.J.; Klotzbach, Udo; Washio, Kunihiko; Arnold, Craig B.

    2014-01-01

    Laser-induced periodic surface structures (LIPSSs) consist of regular wavy surface structures, or ripples, with amplitudes and periodicity in the sub-micrometer range. A summary of experimentally observed LIPSSs is presented, as well as our model explaining their possible origin. Linearly polarized

  13. Modeling laser-induced periodic surface structures: an electromagnetic approach

    NARCIS (Netherlands)

    Skolski, Johann Zbigniew Pierre

    2014-01-01

    This thesis presents and discusses laser-induced periodic surface structures (LIPSSs), as well as a model explaining their formation. LIPSSs are regular wavy surface structures with dimensions usually in the submicrometer range, which can develop on the surface of many materials exposed to laser rad

  14. Overview of applications of Laser-Induced Breakdown Spectroscopy (LIBS)

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy (LIBS) is a method of performing elemental analyses of solids, liquids, and gases using the microplasma produced by a focused laser pulse. Because the microplasma is formed by optical radiation, LIBS has some important advantages compared to conventional laboratory based analytical methods. Three applications are discussed which use the LIBS method. 6 refs., 8 figs., 2 tabs

  15. MOLECULAR ION DETECTION BY A LASER INDUCED CHANGE IN MOBILITY

    OpenAIRE

    Walkup, R.; Dreyfus, R.; Avouris, Ph.

    1983-01-01

    We report the optogalvanic detection of molecular ions (N+2, CO+) via a laser induced change in ion mobility. The technique relies on a difference in collision limited transport of excited vs. ground state ions, and provides a uniquely sensitive probe of ions in the cathode sheath region of glow discharges.

  16. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Stampanoni-Panariello, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A.D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  17. Laser-Induced Breakdown Spectroscopy and Chlorophyll a Flourescence Transients

    DEFF Research Database (Denmark)

    Frydenvang, Jens

    trustworthy results of a sufficient quality; something that remains a problem for many in-situ methods. In my PhD, I present my work with two such in-situ methods, Laser-Induced Breakdown Spectroscopy (LIBS) and OJIP transients, the rising part of chlorophyll a fluorescence transients from dark-adapted leaves....

  18. Comparison of laser induced plasma and arc discharge emission spectra of Al, Fe, Cu and C

    International Nuclear Information System (INIS)

    Emission spectra of laser induced plasma and arc discharge were measured and compared for Al, Fe, Cu and C. Such a comparison shows a higher presence of ionized transitions, but also a higher background in the emission spectra of laser induced plasma than in arc discharge. It can be concluded that in general it is not possible to predict laser induced plasma for material analysis purposes, calibration by reference laser induced plasma spectra of pure elements in vacuum will be necessary. (Authors)

  19. Remodelling of choroidal blood flow in radiation choroidopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hideo; Muraoka, Kanemitsu; Takahashi, Kyoichi; Sutoh, Noriko [Gunma Univ., Maebashi (Japan). School of Medicine

    1997-02-01

    Two males, aged 68 and 34 years each, presented with radiation retinopathy. One had received radiation therapy to the whole brain for intracranial metastasis of lung carcinoma 29 months before. The other underwent surgery and radiation for melanoma of the upper eyelid 15 years before. When examined by indocyanine green angiography. both cases showed vasoocclusive changes in the choroid involving the choriocapillaris and major vessels in the affected fundus area. In one eye with severe retinal vascular lesions in the superior temporal quadrant, the vortex vein in the quadrant had obliterated. The venous blood in this quadrant was drained into the inferior temporal vortex vein crossing the presumed watershed zone temporal to the macula. Collaterals had formed between choroidal arteries and between choroidal veins. These cases illustrate that choroidal vascular lesions may be present in radiation retinopathy, that the former may be more pronounced than the latter and that choroidal vessels may undergo extensive remodelling to compensate for the disturbed choroidal circulation. (author)

  20. CT of malignant choroidal melanoma - morphology and perfusion characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Heller, M.; Hagemann, J.; Jend, H.H.; Guthoff, R.

    1982-03-01

    The computed tomographic morphology of malignant choroidal melanoma and its perfusion characteristics are described. Thirty-three static and serial CT examinations made on 29 patients with choroidal melanoma, three with pseudotumors of the macula and one with choroidal metastasis revealed the choroidal melanoma to be usually a hyperdense, markedly perfused tumor, while the non-contrast, diagnostically undifferentiable pseudotumors and the choroidal metastasis, revealed no significant change in density after the administration of contrast material. Density values or perfusion characteristics of choroidal melanoma that are outside of the normal range are a result of secondary changes within the immediate surroundings of the tumor, such as detachment of the retina, tumor-induced glaucoma, or tumor necrosis.

  1. Choroid Melanoma Metastasis to Spine: A Rare Case Report

    Directory of Open Access Journals (Sweden)

    Hiren Mandaliya

    2016-01-01

    Full Text Available Metastatic choroid melanoma is a highly malignant disease with a limited life expectancy. The liver is the most common site for metastasis of uveal melanoma followed by lung, bone, skin, and subcutaneous tissue. Metastasis from choroidal melanoma usually occurs within the first five years of treatment for primary tumours. Metastatic choroid melanoma to the spine/vertebrae is extremely rare. We report the first case of spinal metastasis from choroid melanoma in a 61-year-old man who had been treated for primary ocular melanoma three years earlier with radioactive plaque brachytherapy. Synchronously, at the time of metastasis, he was also diagnosed as having a new primary lung adenocarcinoma as well. The only other case reported on vertebral metastasis from malignant melanoma of choroid in literature in which primary choroid melanoma was enucleated.

  2. High Frequency Color Doppler Image of Choroidal Detachment

    Institute of Scientific and Technical Information of China (English)

    JinghongWu; LijuanZou; 等

    2002-01-01

    Purpose:To study the Color Doppler Image (CDI) characteristics of choroidal detachment and the applied value of CDI.Methods:Seventy-two cases (74 eyes) of choroidal detachment were studied retrospectively.Results:The typical ultragraph of chroridal detachment displayed one or several smooth hemispherical or lobuler circular thick bands, with convex side toward vitreous cavity.Most of the choroidal detachments were located before the equator, a few of them were beyond the equator.CDI displayed blood flow singnal in the band.Pulse Doppler showed the frequency spectrum features of retinal detachment band were similar to those of central retinal vessels, whereas the frequency spectum features of choroidal detachment bend resembled those of ciliary artery in some cases of retinal detachment (RD) accompanied by choroidal detachment.Conclusion:CDI could make a correct and precise diagnosis of choroidal detachment.Eye Science 2000;16:61-64.

  3. Choroidal metastasis from tubulopapillary renal cell carcinoma: a case report

    OpenAIRE

    Elghissassi, Ibrahim; Inrhaoun, Hanane; Ismaili, Nabil; Errihani, Hassan

    2009-01-01

    Choroidal metastases from renal carcinoma are rare. Most reported cases describe a clear cell carcinoma histologic subtype. Metastatic tubulopapillary renal cell carcinoma to the choroid plexus is very exceptional. We report the case of a 31-year-old man with a history of tubulopapillary renal cell carcinoma who presented two years later with metastatic disease to lungs and presternal soft tissue and three months after with choroidal metastasis revealed on ophtalmoscopic examination and magne...

  4. Diabetic Retinal and Choroidal Edema in SDT Rats

    OpenAIRE

    Fumihiko Toyoda; Yoshiaki Tanaka; Machiko Shimmura; Nozomi Kinoshita; Hiroko Takano; Akihiro Kakehashi

    2015-01-01

    We evaluated the features of diabetic retinal and choroidal edema in Spontaneously Diabetic Torii (SDT) rats. We measured the retinal and choroidal thicknesses in normal Sprague-Dawley (SD) rats (n = 9) and SDT rats (n = 8). The eyes were enucleated 40 weeks later after they were diagnosed with diabetes, and 4-micron sections were cut for conventional histopathologic studies. The mean retinal and choroidal thicknesses were significantly thicker in the SDT rats than in the normal SD rats. The ...

  5. Current perspectives of herpesviral retinitis and choroiditis.

    Science.gov (United States)

    Madhavan, H N; Priya, K; Biswas, J

    2004-10-01

    Vision-threatening viral retinitis are primarily caused by members of the herpesvirus family. The biology and molecular characterization of herpesviruses, clinical presentations of retinopathies, pathology and pathogenesis including the host responses, epidemiology and the laboratory methods of aetiological diagnosis of these diseases are described. Clinical syndromes are acute retinal necrosis (ARN), progressive outer retinal necrosis (PORN), cytomegalovirus (CMV) retinitis, multifocal choroiditis and serpiginous choroiditis besides other viral retinopathies. Herpes simplex virus (HSV) retinitis is more common in immunocompetent persons while varicella zoster virus (VZV) affects both immunocompetent and immunosuppressed patients equally. CMV retinitis is most common among patients with AIDS. The currently employed laboratory methods of antigen detection, virus isolation and antibody detection by enzyme linked immuno-sorbent assay (ELISA) have low sensitivity. Polymerase chain reaction (PCR) has increased the value of diagnosis due to its high clinical sensitivity and absolute specificity in detection of herpesviruses in intraocular specimens. PMID:16295367

  6. Choroid plexus transport: gene deletion studies

    Directory of Open Access Journals (Sweden)

    Keep Richard F

    2011-11-01

    Full Text Available Abstract This review examines the use of transporter knockout (KO animals to evaluate transporter function at the choroid plexus (the blood-CSF barrier; BCSFB. Compared to the blood-brain barrier, there have been few such studies on choroid plexus (CP function. These have primarily focused on Pept2 (an oligopeptide transporter, ATP-binding cassette (ABC transporters, Oat3 (an organic anion transporter, Svct2 (an ascorbic acid transporter, transthyretin, ion transporters, and ion and water channels. This review focuses on the knowledge gained from such studies, both with respect to specific transporters and in general to the role of the CP and its impact on brain parenchyma. It also discusses the pros and cons of using KO animals in such studies and the technical approaches that can be used.

  7. Idiopathic polypoidal choroidal vasculopathy masquerading as choroidal tumors: one year follow-up of a peripheral lesion

    Directory of Open Access Journals (Sweden)

    Rony Carlos Preti

    2015-06-01

    Full Text Available ABSTRACT This case report describes peripheral idiopathic polypoidal choroidal vasculopathy (IPCV with a collection of small aneurysmal dilations that masqueraded as choroidal tumors in an elderly patient. A 68-year-old African American woman was referred to us with a suspected diagnosis of asymptomatic vascular choroidal tumor and choroidal capillary hemangioma, affecting the temporal peripheral fundus. Upon examination, optical coherence tomography (OCT revealed two large hemorrhagic pigment epithelium detachments (PED, and indocyanine green angiography (ICG confirmed the diagnosis of IPCV. One year later, there was reduction in the hemorrhagic pigment epithelium detachments and the lesion took on a different appearance, resembling a choroidal osteoma. No treatment was necessary despite the presence of multiple polyps. IPCV is a rare condition that can resemble other choroidal diseases depending on the stage of presentation. OCT is the best tool to determine the characteristics of the lesions, and indocyanine green angiography should be used to confirm the diagnosis. Not all cases require treatment.

  8. The normal choroidal thickness in southern Thailand

    OpenAIRE

    Jirarattanasopa P; Panon N; Hiranyachattada S; Bhurayanontachai P

    2014-01-01

    Pichai Jirarattanasopa,1 Nisa Panon,2 Siriphun Hiranyachattada,2 Patama Bhurayanontachai1 1Department of Ophthalmology, Faculty of Medicine, 2Department of Physiology, Faculty of Science, Prince of Songkla University, Hat Yai, Thailand Objective: To investigate the association between subfoveal choroidal thickness in healthy southern Thailand volunteers and age, axial length, and refractive error.Subjects and methods: This was a prospective cross-sectional case series. A total of 210&n...

  9. The normal choroidal thickness in southern Thailand

    OpenAIRE

    Jirarattanasopa, Pichai

    2014-01-01

    Pichai Jirarattanasopa,1 Nisa Panon,2 Siriphun Hiranyachattada,2 Patama Bhurayanontachai1 1Department of Ophthalmology, Faculty of Medicine, 2Department of Physiology, Faculty of Science, Prince of Songkla University, Hat Yai, Thailand Objective: To investigate the association between subfoveal choroidal thickness in healthy southern Thailand volunteers and age, axial length, and refractive error.Subjects and methods: This was a prospective cross-sectional case series. A total of 2...

  10. Is Asthma Related to Choroidal Neovascularization?

    OpenAIRE

    Yaoyao Sun; Wenzhen Yu; Lvzhen Huang; Jing Hou; Peihua Gong; Yi Zheng; Mingwei Zhao; Peng Zhou; Xiaoxin Li

    2012-01-01

    BACKGROUND: Age-related degeneration (AMD) and asthma are both diseases that are related to the activation of the complement system. The association between AMD and asthma has been debated in previous studies. The authors investigated the relationship between AMD and asthma systemically. PRINCIPAL FINDINGS: The epidemiological study showed that asthma was related to choroidal neovascularization (CNV) subtype (OR = 1.721, P = 0.023). However, the meta-analysis showed there was no association b...

  11. Central Serous Chorioretinopathy Mistaken for Tuberculous Choroiditis

    OpenAIRE

    Marina Papadia; Herbort, Carl P.

    2011-01-01

    Purpose: To report a patient erroneously diagnosed with tuberculous choroiditis who was accordingly treated with long term steroids which in turn, worsened the actual disease process that turned out to be central serous chorioretinopathy (CSC). Case Report: A 59-year-old Caucasian man developed a chorioretinal disease in his right eye in 1997. Having a positive tuberculin skin test, tuberculous chorioretinitis was suspected and antituberculous therapy was administered for 4 months. In 200...

  12. NSAIDs inhibit neovascularization of choroid through HO-1-dependent pathway.

    Science.gov (United States)

    Yoshinaga, Narimasa; Arimura, Noboru; Otsuka, Hiroki; Kawahara, Ko-Ichi; Hashiguchi, Teruto; Maruyama, Ikuro; Sakamoto, Taiji

    2011-09-01

    Intraocular neovascularization is the leading cause of severe visual loss and anti-vascular endothelial growth factor (VEGF) therapy is currently performed for choroidal neovascularization (CNV). Despite its potent anti-angiogenic effect, there are concerns about its long-term safety. Non-steroidal anti-inflammatory drugs (NSAIDs) are common therapeutic agents used for treating inflammatory diseases, and their anti-stress effects are attracting attention now. We studied the effects of topical NSAIDs on CNV, focusing on anti-stress proteins. Cultured retinal pigment epithelium (RPE) cells were treated with NSAIDs: bromfenac, indomethacin, or vehicle control. Transcription factor NF-E2-related factor 2 (Nrf2) and its downstream anti-oxidant protein heme oxygenase (HO)-1 were assessed using western blot and immunohistochemistry. As a result, NSAIDs induced translocation of Nrf2 into the nucleus and the robust expression of HO-1 in a dose- and time-dependent manner. Flow cytometric analysis revealed that bromfenac inhibited H(2)O(2)-induced apoptosis in cultured RPE cells. Next, we studied the effects of topical bromfenac on laser-induced CNV model in rat. The expressions of Nrf2 and HO-1, infiltrations of ED-1-positive macrophages at CNV lesions and size were analyzed. VEGF in the ocular fluid of these rats was also measured using enzyme-linked immunosorbent assay. Rats administered an inhibitor of HO-1 stannic mesoporphyrin (SnMP) were also studied. The results showed that topical bromfenac led to translocation of Nrf2 and induction of HO-1 in CNV lesions and that the number of infiltrating macrophages at the CNV lesion decreased. The sizes of CNV lesions were significantly smaller in bromfenac-treated rats than control CNV, and the effects were diminished by SnMP. VEGF increased in the ocular fluid after laser treatment and was inhibited by bromfenac and SnMP canceling these effects. NSAIDs inhibit CNV through the novel anti-stress protein HO-1-dependent pathway

  13. Combination therapy of low-fluence photodynamic therapy and intravitreal ranibizumab for choroidal neovascular membrane in choroidal osteoma

    Directory of Open Access Journals (Sweden)

    Rodney J Morris

    2011-01-01

    Full Text Available Choroidal osteoma is an unusual form of intraocular calcification seen in otherwise healthy eyes. It is a benign idiopathic osseous tumor of the choroid, typically seen in young females. Choroidal neovascular membrane (CNVM is a complication seen in one-third of these patients and carries a poor visual outcome. We report a case of a 25-year-old hyperthyroid female with choroidal osteoma and subfoveal CNVM in her left eye which was successfully treated using low-fluence photodynamic therapy (PDT with verteporfin followed by a single injection of intravitreal ranibizumab.

  14. Supersonic laser-induced jetting of aluminum micro-droplets

    International Nuclear Information System (INIS)

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets

  15. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  16. Anisotropy of Laser-Induced Bulk Damage of Single Crystals

    CERN Document Server

    Krupych, O; Smaga, I; Vlokh, R

    2005-01-01

    The regularities of laser-induced damage of anisotropic materials, such as LiNbO3 and KDP dielectric single crystals, are experimentally studied. It is revealed that the shape of laser-induced damage in the dielectric crystals depends on the elastic symmetry of crystal and the propagation direction of the laser beam. When the beam propagates along the optic axis of crystals, the figures of the laser damage are six-path stars for LiNbO3 and four-path ones for KDP crystals. For the direction parallel to X and Y axes in KDP crystal, the damage has initially cross-like configuration, with further splitting of Z-oriented crack into two cracks in the process of damage evolution, leading to transformation of orthogonal-type damage to a hexagonal-type one.

  17. Applications of laser-induced gratings to spectroscopy and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, E.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program has traditionally emphasized two principal areas of research. The first is the spectroscopic characterization of large-amplitude motion on the ground-state potential surface of small, transient molecules. The second is the reactivity of carbonaceous clusters and its relevance to soot and fullerene formation in combustion. Motivated initially by the desire to find improved methods of obtaining stimulated emission pumping (SEP) spectra of transients, most of our recent work has centered on the use of laser-induced gratings or resonant four-wave mixing in free-jet expansions. These techniques show great promise for several chemical applications, including molecular spectroscopy and photodissociation dynamics. The author describes recent applications of two-color laser-induced grating spectroscopy (LIGS) to obtain background-free SEP spectra of transients and double resonance spectra of nonfluorescing species, and the use of photofragment transient gratings to probe photodissociation dynamics.

  18. Laser-induced periodic surface structuring of biopolymers

    Science.gov (United States)

    Pérez, Susana; Rebollar, Esther; Oujja, Mohamed; Martín, Margarita; Castillejo, Marta

    2013-03-01

    We report here on a systematic study about the formation of laser-induced periodic surface structures (LIPSS) on biopolymers. Self-standing films of the biopolymers chitosan, starch and the blend of chitosan with the synthetic polymer poly (vinyl pyrrolidone), PVP, were irradiated in air with linearly polarized laser beams at 193, 213 and 266 nm, with pulse durations in the range of 6-17 ns. The laser-induced periodic surface structures were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via Raman spectroscopy. Formation of LIPSS parallel to the laser polarization direction, with periods similar to the laser wavelength, was observed at efficiently absorbed wavelengths in the case of the amorphous biopolymer chitosan and its blend with PVP, while formation of LIPSS is prevented in the crystalline starch biopolymer.

  19. Analysis of organic vapors with laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor

  20. Analysis of organic vapors with laser induced breakdown spectroscopy

    Science.gov (United States)

    Nozari, Hadi; Rezaei, Fatemeh; Tavassoli, Seyed Hassan

    2015-09-01

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  1. Analysis of organic vapors with laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nozari, Hadi; Tavassoli, Seyed Hassan [Laser and Plasma Research Institute, Shahid Beheshti University, G. C, 1983963113 Evin, Tehran (Iran, Islamic Republic of); Rezaei, Fatemeh, E-mail: fatemehrezaei@kntu.ac.ir [Department of Physics, K. N. Toosi University of Technology, 15875-4416 Shariati, Tehran (Iran, Islamic Republic of)

    2015-09-15

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  2. Laser induced breakdown spectroscopy stratigraphic characterization of multilayered painted surfaces

    International Nuclear Information System (INIS)

    Laser spectroscopy techniques are modern and competitive methods for elemental analysis. Laser induced breakdown spectroscopy (LIBS), due to its advantages as minimally invasive method that provides real time monitoring and selectivity, is a suitable tool to analyze sample composition. Based on the known emission spectra of heavy metals such as Pb, Zn, Au, Ca, a stratigraphic study regarding the identification of the painting layers content of different mock-up samples was performed. LIBS was used to monitor the laser induced stepwise selective removal of the painting layers and to analyze their composition. The obtained LIBS spectra were correlated with profilometric measurements. - Highlights: ► LIBS was used to analyze heavy metals in mock-up painting samples. ► LIBS data are correlated with profilometric and optical microscopy measurements. ► Appropriate analysis parameters are provided for some materials used in painting.

  3. Time-resolved laser-induced breakdown spectroscopy of aluminum

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-yun; ZHANG Wei-jun; WANG Zhen-ya; HAO Li-qing; HUANG Ming-qiang; ZHAO Wen-wu; LONG Bo; Zhao Wei

    2008-01-01

    We develop a system to measure the elemental composition of unprepared samples using laser-induced breakdown spectroscopy (LIBS) in our laboratory, which can be used for the determination of elements in solids, liquids and aerosols. A description of the instrumentation, including laser, sample chamber and detection, is followed by a brief discussion. The time-resolved LIBS of aluminum at atmospheric pressure is presented. At the end, the possibilities and later uses of this technique are briefly discussed.

  4. Modeling laser-induced periodic surface structures: an electromagnetic approach

    OpenAIRE

    Skolski, Johann Zbigniew Pierre

    2014-01-01

    This thesis presents and discusses laser-induced periodic surface structures (LIPSSs), as well as a model explaining their formation. LIPSSs are regular wavy surface structures with dimensions usually in the submicrometer range, which can develop on the surface of many materials exposed to laser radiation. The most common type of LIPSSs, which can be produced with continuous wave lasers or pulsed lasers, have a periodicity close to the laser wavelength and a direction orthogonal to the polari...

  5. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  6. Role of Planar Laser-Induced Fluorescence in Combustion Research.

    OpenAIRE

    Grisch, F.; Orain, M.

    2009-01-01

    Laser diagnostics are now considered an indispensable tool in fluid dynamics research. Such measurements provide a deeper understanding of the inner physical and chemical processes, which is required to validate and improve computer-based simulations and to assist applied research in practical combustors. This paper presents an overview of the potential of planar laser-induced fluorescence (PLIF), which currently allows for the imaging of scalar properties such as species concentration, tempe...

  7. Laser-induced transient grating setup with continuously tunable period

    Energy Technology Data Exchange (ETDEWEB)

    Vega-Flick, A. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Applied Physics Department, CINVESTAV-Unidad Mérida, Carretera Antigua a Progreso Km 6, Cordemex, Mérida, Yucatán 97310 Mexico (Mexico); Eliason, J. K.; Maznev, A. A.; Nelson, K. A., E-mail: kanelson@mit.edu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Khanolkar, A.; Abi Ghanem, M.; Boechler, N. [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Alvarado-Gil, J. J. [Applied Physics Department, CINVESTAV-Unidad Mérida, Carretera Antigua a Progreso Km 6, Cordemex, Mérida, Yucatán 97310 Mexico (Mexico)

    2015-12-15

    We present a modification of the laser-induced transient grating setup enabling continuous tuning of the transient grating period. The fine control of the period is accomplished by varying the angle of the diffraction grating used to split excitation and probe beams. The setup has been tested by measuring dispersion of bulk and surface acoustic waves in both transmission and reflection geometries. The presented modification is fully compatible with optical heterodyne detection and can be easily implemented in any transient grating setup.

  8. Laser-induced transient grating setup with continuously tunable period

    International Nuclear Information System (INIS)

    We present a modification of the laser-induced transient grating setup enabling continuous tuning of the transient grating period. The fine control of the period is accomplished by varying the angle of the diffraction grating used to split excitation and probe beams. The setup has been tested by measuring dispersion of bulk and surface acoustic waves in both transmission and reflection geometries. The presented modification is fully compatible with optical heterodyne detection and can be easily implemented in any transient grating setup

  9. Remote sensing vegetation status by laser-induced fluorescence

    International Nuclear Information System (INIS)

    In November 1989 the EUREKA project LASFLEUR (EU 380) started as an European research effort to investigate the future application of far-field laser-induced plant fluorescence for synoptic, airborne environmental monitoring of vegetation. This report includes a brief introduction in a theoretically approach for the laser-induced fluorescence signals of leaves and their spectral and radiometric behaviour. In addition, a detailed description of the design and realization of the second generation of the far-field fluorescence lidar (DLidaR-2) is given with special regard to the optical and electronical setup, followed by a short explanation of the data processing. The main objectives of the far field measurements are to demonstrate the link between laser-induced fluorescence data and plant physiology and to show the reliability of remote single shot lidar measurements. The data sets include the typical daily cycles of the fluorescence for different global irradiation. As expected from biophysical models, the remotely sensed chlorophyll fluorescence is highly correlated with the carbon fixation rate, while the fluorescence ratio F685 / F730 is only dependent on the chlorophyll concentration. Drought stress measurement of evergreen oaks Quercus pubescens confirm the findings of healthy plants with regard to the fluorescence ratio F685 / F730 while the fluorescence signals of stressed plants show a different behavior than nonstressed plants. Additionally, the corresponding physiological data (porometer and PAM data) are presented. (author)

  10. Correlation between grade of pearlite spheroidization and laser induced spectra

    International Nuclear Information System (INIS)

    Laser induced breakdown spectroscopy (LIBS) which is used traditionally as a spectrochemical analytical technique was employed to analyze the grade of pearlite spheroidization. Three 12Cr1MoV steel specimens with different grades of pearlite spheroidization were ablated to produce plasma by pulse laser at 266 nm. In order to determine the optimal temporal condition and plasma parameters for correlating the grade of pearlite spheroidization and laser induced spectra, a set of spectra at different delays were analyzed by the principal component analysis method. Then, the relationship between plasma temperature, intensity ratios of ionic to atomic lines and grade of pearlite spheroidization was studied. The analysis results show that the laser induced spectra of different grades of pearlite spheroidization can be readily identifiable by principal component analysis in the range of 271.941–289.672 nm with 1000 ns delay time. It is also found that a good agreement exists between the Fe ionic to atomic line ratios and the tensile strength, whereas there is no obvious difference in the plasma temperature. Therefore, LIBS may be applied not only as a spectrochemical analytical technique but also as a new way to estimate the grade of pearlite spheroidization. (paper)

  11. Diatomic Molecular Emission Spectroscopy of Laser-induced Titanium Plasma

    International Nuclear Information System (INIS)

    Previous research regarding laser-induced breakdown spectroscopy (LIBS) of titanium normally focuses on the atomic and ionic Ti spectral transition lines. However, after a characteristic time subsequent to laser ablation, these lines are no longer discernable. During this temporal regime, the diatomic molecular transition lines of titanium monoxide (TiO) are prominent in the laser-induced plasma (LIP) emissions. TiO has long been studied in the contexts of stellar emissions, allowing for some of the molecular transition bands to be accurately computed from theory. In this research, optical emission spectroscopy (OES) of laser-induced plasma (LIP) generated by laser ablation of titanium is performed in order to infer temperature as a function of time subsequent to plasma formation. The emission spectra of the resulting ablation plume is imaged as a function of height above the sample surface. Temperatures are inferred over time delays following plasma formation ranging from 20 μs-200 μs. Computed TiO A3Φ – X3Δ, Δv = 0 transition lines are fit to spectral measurements in order to infer temperature. At tdelay = 20 μs-80 μs, the observed plume contains two luminescent regions each with a distinctly different temperature. As the plume evolves in time, the two regions combine and an overall temperature increase is observed

  12. Effects of vasoactive stimuli on blood flow to choroid plexus

    International Nuclear Information System (INIS)

    The goal of this study was to examine effects of vasoactive stimuli on blood flow to choroid plexus. The authors used microspheres to measure blood flow to choroid plexus and cerebrum in anesthetized dogs and rabbits. A critical assumption of the microsphere method is that microspheres do not pass through arteriovenous shunts. Blood flow values obtained with simultaneous injection of 15- and 50-μm microspheres were similar, which suggest that shunting of 15-μm microspheres was minimal. Blood flow to choroid plexus under control conditions was 287 ± 26 (means ± SE) ml · min-1 · 100 g-1 in dogs and 385 ± 73 ml · min-1 100 g-1 in rabbits. Consecutive measurements under control conditions indicated that values for blood flow are reproducible. Adenosine did not alter blood flow to cerebrum but increased blood flow to choroid plexus two- to threefold in dogs and rabbits. Norepinephrine and phenylephrine did not affect blood flow to choroid plexus and cerebrum but decreased blood flow to choroid plexus by ∼ 50%. The authors suggest that (1) the microsphere method provides reproducible valid measurements of blood flow to the choroid plexus in dogs and rabbits and (2) vasoactive stimuli may have profoundly different effects on blood flow to choroid plexus and cerebrum

  13. Clinical Features of Choroidal Metastases from Carcinoid Tumour

    Institute of Scientific and Technical Information of China (English)

    Huaning She; Yuping Zheng; Xiaohua Wang; Yanlong Quan; Naixue Sun

    2004-01-01

    Purpose :To report ophthalmologic and angiographic features of choroidal metastases from carcinoid tumor and analyze their common clinical manifestation.Methods:Ophthalmologic examinations and fundus fluorescein angiography (FFA) were performed in 30 patients suffered from carcinoid tumor, and four patients diagnosed of breast cancer (2 cases), lung cancer (1 case) and maxillary sinus cancer (1 case) were confirmed with choroidal metastases.Results:Choroidal metastases were found as the initial manifestations of the malignant tumors on 2 patients whose initial and chief complaints were decreasing vision, their fundus lesions were mainly presented in the posterior pole and FFA showed high density of fluorescence of the lesions.Conclusions:This study indicated choroidal metastasis might be the first sign of metastases for patients with cancer. For patients with unknown metastastic cancers, examinations of the choroids may be useful for diagnosis and prognosis. Eye Science 2004;20:15-18.

  14. Diabetic Retinal and Choroidal Edema in SDT Rats.

    Science.gov (United States)

    Toyoda, Fumihiko; Tanaka, Yoshiaki; Shimmura, Machiko; Kinoshita, Nozomi; Takano, Hiroko; Kakehashi, Akihiro

    2016-01-01

    We evaluated the features of diabetic retinal and choroidal edema in Spontaneously Diabetic Torii (SDT) rats. We measured the retinal and choroidal thicknesses in normal Sprague-Dawley (SD) rats (n = 9) and SDT rats (n = 8). The eyes were enucleated 40 weeks later after they were diagnosed with diabetes, and 4-micron sections were cut for conventional histopathologic studies. The mean retinal and choroidal thicknesses were significantly thicker in the SDT rats than in the normal SD rats. The choroidal thickness was correlated strongly with the retinal thickness in both rat models. Diabetic retinopathy (DR) and diabetic choroidopathy appeared as edema in the SDT rats. The retinal thickness was correlated strongly with the choroidal thickness in the SDT rats, which is an ideal animal model of both DR and choroidopathy. PMID:26783535

  15. Recurrent Annular Peripheral Choroidal Detachment after Trabeculectomy

    Directory of Open Access Journals (Sweden)

    Shaohui Liu

    2013-10-01

    Full Text Available We report a challenging case of recurrent flat anterior chamber without hypotony after trabeculectomy in a 54-year-old Black male with a remote history of steroid-treated polymyositis, cataract surgery, and uncontrolled open angle glaucoma. The patient presented with a flat chamber on postoperative day 11, but had a normal fundus exam and intraocular pressure (IOP. Flat chamber persisted despite treatment with cycloplegics, steroids, and a Healon injection into the anterior chamber. A transverse B-scan of the peripheral fundus revealed a shallow annular peripheral choroidal detachment. The suprachoroidal fluid was drained. The patient presented 3 days later with a recurrent flat chamber and an annular peripheral choroidal effusion. The fluid was removed and reinforcement of the scleral flap was performed with the resolution of the flat anterior chamber. A large corneal epithelial defect developed after the second drainage. The oral prednisone was tapered quickly and the topical steroid was decreased. One week later, his vision decreased to count fingers with severe corneal stromal edema and Descemet's membrane folds that improved to 20/50 within 24 h of resumption of the oral steroid and frequent topical steroid. The patient's visual acuity improved to 20/20 following a slow withdrawal of the oral and topical steroid. Eight months after surgery, the IOP was 15 mm Hg without glaucoma medication. The detection of a shallow anterior choroidal detachment by transverse B-scan is critical to making the correct diagnosis. Severe cornea edema can occur if the steroid is withdrawn too quickly. Thus, steroids should be tapered cautiously in steroid-dependent patients.

  16. Laser induced vibration of a thin soap film.

    OpenAIRE

    Emile, Olivier; Emile, Janine

    2014-01-01

    We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be implemented in an optofluidic...

  17. UV laser induced photochemistry of nitrobenzene and nitrotoluene isomers

    Energy Technology Data Exchange (ETDEWEB)

    Kosmidis, C.; Clark, A.; Deas, R.M.; Ledingham, K.W.D.; Marshall, A.; Singhal, R.P. [Glasgow Univ. (United Kingdom). Dept. of Physics and Astronomy

    1995-03-01

    The photofragmentation of nitrobenzene and the isomers of nitrotoluene in the gas phase are studied in the wavelength region 210-270 nm using a pulsed UV laser in conjunction with a time of flight mass spectrometer. Laser induced mass spectra are analysed and compared with those produced by the electron impact (EI) technique. The generation of the observed fragment ions is explained by invoking different fragmentation pathways followed by these molecules. Observed differences in the mass spectra of the o-, m-, and p-nitrotoluene isomers are discussed as a possible way for a laser based method for their identification. (author).

  18. Computer simulations of laser-induced melting of aluminum

    International Nuclear Information System (INIS)

    Laser-induced solid-to-liquid phase transitions in 100 nm aluminum film were simulated using a hybrid model that combines molecular dynamics (MD) with a continuum description of the laser excitation and a two-temperature method (TTM) to model the relaxation of conduction band electrons. When the laser fluence provides more energy than needed for a complete melting of the film, the phase transition is characterized by an ultrafast collapse of the crystal structure within 2–3 ps. Otherwise, the transition involves a homogeneous nucleation and growth of liquid zones inside the crystal and a heterogeneous propagation of transition fronts from the external surfaces or nucleated liquid zones

  19. The performance and application of laser-induced photoacoustic spectrometer

    International Nuclear Information System (INIS)

    Laser-induced photoacoustic spectrometer (LIPAS) is a key instrument can be used in the investigation of radionuclides migration behaviors due to its higher sensitivity for the detection and identification of radionuclides speciation in aqueous solutions. The speciation of radionuclides such as oxidation states and complexation may be determined directly by using this specific non-contact and nondestructive analytical technique, and the sensitivity of LIPAS surpasses that of conventional absorption spectroscopy by one to two orders of magnitude. In the present work, LIPAS system was established at China Institute of Atomic Energy (CIAE), and the principle, performance and preliminary application of LIPAS are also be presented. (authors)

  20. Laser-induced micro-jetting from armored droplets

    Science.gov (United States)

    Marston, J. O.; Thoroddsen, S. T.

    2015-07-01

    We present findings from an experimental study of laser-induced cavitation within a liquid drop coated with a granular material, commonly referred to as "armored droplets" or "liquid marbles." The cavitation event follows the formation of plasma after a nanosecond laser pulse. Using ultra-high-speed imaging up to 320,610 fps, we investigate the extremely rapid dynamics following the cavitation, which manifests itself in the form of a plethora of micro-jets emanating simultaneously from the spaces between particles on the surface of the drop. These fine jets break up into droplets with a relatively narrow diameter range, on the order of 10 μm.

  1. Laser induced sonofusion: A new road toward thermonuclear reactions

    OpenAIRE

    Rasoul Sadighi-Bonabi; Maryam Gheshlaghi

    2016-01-01

    The Possibility of the laser assisted sonofusion is studied via single bubble sonoluminescence (SBSL) in Deuterated acetone (C3D6O) using quasi-adiabatic and hydro-chemical simulations at the ambient temperatures of 0 and −28.5 °C. The interior temperature of the produced bubbles in Deuterated acetone is 1.6 × 106 K in hydro-chemical model and it is reached up to 1.9 × 106 K in the laser induced SBSL bubbles. Under these circumstances, temperature up to 107 K can be produced in the center of ...

  2. Laser-induced backward transfer of nanoimprinted polymer elements

    Science.gov (United States)

    Feinaeugle, Matthias; Heath, Daniel J.; Mills, Benjamin; Grant-Jacob, James A.; Mashanovich, Goran Z.; Eason, Robert W.

    2016-04-01

    Femtosecond laser-induced backward transfer of transparent photopolymers is demonstrated in the solid state, assisted by a digital micromirror spatial light modulator for producing shaped deposits. Through use of an absorbing silicon carrier substrate, we have been able to successfully transfer solid-phase material, with lateral dimensions as small as ~6 µm. In addition, a carrier of silicon incorporating a photonic waveguide relief structure enables the transfer of imprinted deposits that have been accomplished with surface features exactly complementing those present on the substrate, with an observed minimum feature size of 140 nm.

  3. Continuous wave laser induced transfer of organic semiconductors

    Czech Academy of Sciences Publication Activity Database

    Fitl, P.; Vrňata, M.; Myslík, V.; Kopecký, D.; Vlček, J.; Tomeček, D.; Novotný, Michal

    Kyoto: JSAP- MRS Joint Symposia 2013, 2013 - (Tabata, H.). JSAP- MRS -B-014-JSAP- MRS -B-014 [JSAP- MRS Joint Symposia 2013. 16.09.2013-20.09.2013, Kyoto] R&D Projects: GA ČR(CZ) GAP108/11/1298 Institutional support: RVO:68378271 Keywords : organic semiconductors * phthalocyanines * Tris-(8-hydroxyquinoline) aluminum * Laser Induced Forward Transfer Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.gakkai-web.net/gakkai/jsap/jsap_mrs/hp/images/temp/ MRS _pro.pdf

  4. UV laser induced photochemistry of nitrobenzene and nitrotoluene isomers

    International Nuclear Information System (INIS)

    The photofragmentation of nitrobenzene and the isomers of nitrotoluene in the gas phase are studied in the wavelength region 210-270 nm using a pulsed UV laser in conjunction with a time of flight mass spectrometer. Laser induced mass spectra are analysed and compared with those produced by the electron impact (EI) technique. The generation of the observed fragment ions is explained by invoking different fragmentation pathways followed by these molecules. Observed differences in the mass spectra of the o-, m-, and p-nitrotoluene isomers are discussed as a possible way for a laser based method for their identification. (author)

  5. Remote sensing of phytoplankton using laser-induced fluorescence

    International Nuclear Information System (INIS)

    The results of remote laser sensing of brackish-water phytoplankton on board a research vessel are presented. Field data of laser-induced fluorescence of phytoplankton obtained during the several cruises in the mouth of tile Gulf of Finland are compared with the results of standard chlorophyll a analysis of water samples and phytoplankton species determination by microscopy. The approach of fluorescence excitation by tunable laser radiation is applied to study the spatial distribution of a natural phytoplankton community. The remote analysis of the pigment composition of a phytoplankton community using the method of selective pigment excitation is described. The possibility of elaborating methods of quantitative laser remote biomonitoring is discussed

  6. Laser-Induced Breakdown Spectroscopy (LIBS): specific applications

    Science.gov (United States)

    Trtica, M. S.; Savovic, J.; Stoiljkovic, M.; Kuzmanovic, M.; Momcilovic, M.; Ciganovic, J.; Zivkovic, S.

    2015-12-01

    A short overview of Laser Induced Breakdown Spectroscopy (LIBS) with emphasis on the new trends is presented. Nowadays, due to unique features of this technique, LIBS has found applications in a great variety of fields. Achievements in the application of LIBS in nuclear area, for hazardous materials detection and in geology were considered. Also, some results recently obtained at VINCA Institute, with LIBS system based on transversely excited atmospheric (TEA) CO2 laser, are presented. Future investigations of LIBS will be oriented toward further improvement of the analytical performance of this technique, as well as on finding new application fields.

  7. Chemical consequences of laser-induced breakdown in molecular gases

    Czech Academy of Sciences Publication Activity Database

    Babánková, Dagmar; Civiš, Svatopluk; Juha, Libor

    2006-01-01

    Roč. 30, č. 2-3 (2006), s. 75-88. ISSN 0079-6727 R&D Projects: GA ČR GA203/06/1278; GA MŠk LC510; GA MŠk LC528; GA MŠk 1P04LA235 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100523 Keywords : laser spark * laser-induced dielectric breakdown * laser-plasma chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.500, year: 2006

  8. Identification of asbestos by laser-induced fluorescence microscopy

    International Nuclear Information System (INIS)

    Microscopic studies on laser-induced fluorescence emitted from asbestos (chrysotile) and a building material (glass-wool: an alternative material for asbestos) fibrous particle excited by a ultra-violet (266 nm) laser, have been conducted in an attempt to discriminating asbestos from the other materials. Significant differences in the decay ratio and intensity of the fluorescence were observed between those fibrous particles. The result obtained in this experiment shows that microscopic analysis using the difference in the fluorescence characteristics can be useful for identifying asbestos particles from other building materials under a microscope. (author)

  9. Characterisation of estuarine intertidal macroalgae by laser-induced fluorescence

    DEFF Research Database (Denmark)

    Gameiro, Carla; Utkin, Andrei B.; Sousa Dias Cartaxana, Paulo Jorge

    2015-01-01

    The article reports the application of laser-induced fluorescence (LIF) for the assessment of macroalgae communities of estuarine intertidal areas. The method was applied for the characterisation of fifteen intertidal macroalgae species of the Tagus estuary, Portugal, and adjacent coastal area...... spectra were determined by differences in the main fluorescing pigments: phycoerythrin, phycocyanin and chlorophyll a (Chl a). In the green and brown macroalgae groups, the relative significance of the two emission maxima seems to be related to the thickness of the photosynthetic layer. In thick...

  10. Progress in fieldable laser-induced breakdown spectroscopy (LIBS)

    Science.gov (United States)

    Miziolek, Andrzej W.

    2012-06-01

    In recent years there has been great progress in the Laser Induced Breakdown Spectroscopy (LIBS) technology field. Significant advances have been made both in fundamental and applied research as well as in data processing/chemometrics. Improvements in components, most notably lasers/optics and spectrometers are enabling the development of new devices that are suitable for field use. These new commercial devices recently released to the marketplace, as well as ones currently under development, are bringing the potential of LIBS for CBRNE threat analysis into real-world applications.

  11. Biomedical and environmental applications of laser-induced breakdown spectroscopy

    Indian Academy of Sciences (India)

    V K Unnikrishnan; K S Choudhari; Suresh D Kulkarni; Rajesh Nayak; V B Kartha; C Santhosh; B M Suri

    2014-02-01

    Laser-induced breakdown spectroscopy (LIBS) is an emerging analytical technique with numerous advantages such as rapidity, multi-elemental analysis, minimal sample preparation, minimal destruction, low cost and versatility of being applied to a wide range of materials. In this paper, we report the preliminary observations we obtained using LIBS for clinical and environmental samples. Elemental analysis has been done qualitatively in human teeth samples which show encouraging results. It has also been demonstrated in this paper that LIBS can be very well utilized in field applications such as plastic waste sorting and recycling.

  12. Laser induced breakdown spectroscopy (LIBS) applied to plutonium analysis

    International Nuclear Information System (INIS)

    A Laser Induced Breakdown Spectroscopy (LIBS) system has been developed specifically for the quantitative analysis of gallium in plutonium dioxide in support of the MOX fuel development program. The advantage of this system is no sample preparation and the capability to analyze extremely small samples. Success in this application has prompted an expansion of the technique to other areas, including determination of plutonium isotopic ratios. This paper will present recent results for gallium content in PuO2 after processing via thermally induced gallium removal (TIGR). Data will also be presented for the determination of the plutonium 239/240 isotopic ratio

  13. Infrared laser-induced breakdown spectroscopy emissions from energetic materials

    Science.gov (United States)

    Yang, Clayton S.; Brown, E.; Hommerich, Uwe; Trivedi, Sudhir B.; Samuels, Alan C.; Snyder, A. Peter

    2011-05-01

    Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives (CBE) sensing and has significant potential for real time standoff detection and analysis. We have studied LIBS emissions in the mid-infrared (MIR) spectral region for potential applications in CBE sensing. Detailed MIR-LIBS studies were performed for several energetic materials for the first time. In this study, the IR signature spectral region between 4 - 12 um was mined for the appearance of MIR-LIBS emissions that are directly indicative of oxygenated breakdown products as well as partially dissociated and recombination molecular species.

  14. Laser-Induced-Fluorescence Spectrum of the CNN Molecule

    OpenAIRE

    Curtis, M. C.; Levick, A. P.; Sarre, P. J.

    1988-01-01

    We have recorded a laser excitation spectrum of the A3Π–X3Σ− electronic band system of the CNN radical in the gas phase, at a resolution of ca. 0.8 cm−1. The rotational branch structure of the vibrational band near 419 nm has been simulated and molecular parameters are obtained. The results are compared with data from laser-induced-fluorescence spectra of CNN trapped in a low-temperature matrix. A revised value for the spin-orbit parameter in the A3Π state is obtained and comparison is made w...

  15. Choroidal osteoma secondary to ocular trauma

    International Nuclear Information System (INIS)

    The choroidal osteoma is a benign bony tumor described for the first time in 1978 by Gass and collaborators. It is generally unilateral, with juxtapapillary localization and more frequent in young adult females. It presents unknown etiology, but it is associated to different factors as inflammatory processes, congenital malformations, hormonal alterations and ocular traumas among others. The patient was a 54 year-old woman with a personal history of rheumatic fibromyalgia (osteoarthrosis and osteoporosis) and hypertension. Her ophthalmological antecedent showed myopia and arteriolosclerotic retinopathy. At the beginning of the year, she suffered a traffic accident and was injured in her limbs and periocular region. After this, she began feeling blurred vision of the right eye and she went to our service 6 months later. She was performed an ophthalmologic exam. It was found that the right eye had visual acuity of 0.4, and after correction it reached 1.0. Funduscopy revealed vascular thinness, incomplete posterior vitreous detachment, and a white-orange lesion of 3 papillary diameters that involved inferior temporary arcade with well-defined borders. An angiography was performed, which showed sustained hyperfluorescence and non neovascularization; and the optic coherence tomography revealed a halo of serous retinal detachment. Additionally, the ocular ultrasound yielded a high reflectivity echogenic image that involves choroids with posterior acoustic shadow. It is for this reason that we affirm the traumatic etiology of the lesion. This is a rare pathology that should be diagnosed by imaging techniques. Notably, it is secondary to an ocular trauma

  16. Central Serous Chorioretinopathy Mistaken for Tuberculous Choroiditis

    Directory of Open Access Journals (Sweden)

    Marina Papadia

    2011-01-01

    Full Text Available Purpose: To report a patient erroneously diagnosed with tuberculous choroiditis who was accordingly treated with long term steroids which in turn, worsened the actual disease process that turned out to be central serous chorioretinopathy (CSC. Case Report: A 59-year-old Caucasian man developed a chorioretinal disease in his right eye in 1997. Having a positive tuberculin skin test, tuberculous chorioretinitis was suspected and antituberculous therapy was administered for 4 months. In 2005, visual symptoms in the same eye recurred and despite negative interferon gamma release assay, tuberculous choroiditis was considered as the diagnosis and the patient further received massive corticosteroid therapy along with antituberculous agents. Despite a deteriorating clinical picture, therapy was continued. Upon initial examination at our center, no sign of inflammation was observed and a diagnosis of CSC was made, consequently steroid therapy was terminated. Conclusion: In some chorioretinopathies, it is difficult to differentiate inflammatory from non-inflammatory causes. One should observe the course of the disease and question the initial diagnosis when no improvement or deterioration occurs despite therapy.

  17. Metástasis coroideas Choroidal metastases

    Directory of Open Access Journals (Sweden)

    C. Camarillo

    2008-01-01

    Full Text Available Las metástasis uveales son el tumor intraocular maligno más frecuente y de ellas, más del 80% se localizan en la coroides. Esto, unido al progresivo aumento de la incidencia, hace necesario su estudio y revisión para un correcto diagnóstico y tratamiento en la práctica clínica actual. La etiología varía según el sexo del paciente, siendo el carcinoma de pulmón el que con más frecuencia metastatiza en el varón y el de mama en la mujer. Tienden a la multifocalidad y generalmente se localizan en el polo posterior. En el 50% de los casos cursan de forma asintomática, pero pueden producir pérdida de visión, escotomas, metamorfopsias, y fotopsias. La exploración oftalmoscópica característica muestra una lesión coroidea placoide, homogénea y de aspecto cremoso. En el diagnóstico diferencial se debe considerar el nevus amelanótico, el melanoma amelanótico de coroides, el hemangioma coroideo, la escleritis posterior, el osteoma de coroides, las coriorretinitis, la enfermedad de Harada, el desprendimiento de retina rhegmatógeno, el síndrome de efusión uveal, y la coriorretinopatía serosa central. Una exhaustiva anamnesis y exploración oftalmológica completa son imprescindibles para el diagnóstico, a lo que se pueden añadir como pruebas complementarias la angiografía con fluoresceína, la ecografía ocular, la punción-aspiración con aguja fina (PAAF, la tomografía computarizada y la resonancia magnética. El tratamiento de estos tumores suele ser el tratamiento sistémico del tumor primario; las posibilidades de tratamiento local son la observación, la radioterapia externa, la braquiterapia, la termoterapia transpupilar y la enucleación.Uveal metastases are the most frequent malign intraocular tumour, of which more than 80% are localized in the choroids. This, together with the progressive increase in its incidence, makes its study and review necessary for a correct diagnosis and treatment in current clinical practice

  18. Choroid plexus papilloma in a beluga whale (Delphinapterus leucas).

    Science.gov (United States)

    Thomas, Christian; Mergl, June; Gehring, Erica; Paulus, Werner; Martineau, Daniel; Hasselblatt, Martin

    2016-07-01

    We report herein a choroid plexus papilloma in a beluga whale (Delphinapterus leucas). This case was positive for choroid plexus tumor marker Kir7.1 on immunohistochemistry. These results and the high conservation of Kir7.1 across species at the amino acid sequence level strongly suggest that antibodies directed against Kir7.1 not only can be employed for the diagnosis of choroid plexus tumors in cetaceans, but are also likely to be diagnostically useful in other animal species. PMID:27216722

  19. Bilateral anterior choroidal artery infarction presenting with progressive somnolence.

    Science.gov (United States)

    van Son, Brechtje; Vandevenne, Jan; Viaene, Pieter

    2014-09-01

    A 55-year-old woman was admitted with a 3 days history of increasing lethargy with bradyphrenia and apathy. She progressively developed severe somnolence with marked abulia, right hemiparesis, right hemianopsia, and pseudobulbar palsy. Brain magnetic resonance imaging showed the rare image of bilateral acute anterior choroidal artery infarction. Pseudobulbar mutism and in rare cases abulia have been described in acute anterior choroidal artery infarction contralateral to an older lesion in mirror position. Although neurologic deterioration is not infrequent in anterior choroidal artery territory infarcts, the absence of focal neurologic signs on admission is rare and did not raise suspicion of acute stroke. PMID:25106836

  20. Single shot depth sensitivity using femtosecond Laser Induced Breakdown Spectroscopy

    International Nuclear Information System (INIS)

    Depth profiling measurement using multiple pulse Laser Induced Breakdown Spectroscopy (LIBS) can be used to determine the characteristics of buried layers. However for femtosecond pulses the emission spectra does not necessarily reflect the average depth composition for the single shot case and instead has much higher sensitivity for the surface layer of the ablation region. We introduce a concept of “depth sensitivity” to characterize this behavior for single shot LIBS depth profiling. Experiments were carried out using 800 nm femtosecond laser pulses irradiating layered targets while monitoring the plasma emission with a spectrometer system. Laser induced plasma formed at the surface layer exhibits a strong LIBS signature while deeper ablated region contributes very little to the emission spectrum. The sensitive depth region, the source of the major part of the emission, is much less than the ablation crater depth and is shown to be of the order of 3 nm in the case of actual crater depths of 100's of nm. A two temperature model has been used to determine the lattice temperature profile versus depth which qualitatively predicts the observed behavior. - Highlights: • Depth dependence of LIBS emission within a single 800 nm femtosecond laser shot. • LIBS emission spectra dominated by only a thin surface layer. • Depth sensitivity, a new concept, is ∼3 nm when actual crater depth ∼100’s of nm. • Qualitative agreement with TTM model of lattice temperature versus depth and time

  1. A model for traumatic brain injury using laser induced shockwaves

    Science.gov (United States)

    Selfridge, A.; Preece, D.; Gomez, V.; Shi, L. Z.; Berns, M. W.

    2015-08-01

    Traumatic brain injury (TBI) represents a major treatment challenge in both civilian and military medicine; on the cellular level, its mechanisms are poorly understood. As a method to study the dysfunctional repair mechanisms following injury, laser induced shock waves (LIS) are a useful way to create highly precise, well characterized mechanical forces. We present a simple model for TBI using laser induced shock waves as a model for damage. Our objective is to develop an understanding of the processes responsible for neuronal death, the ways in which we can manipulate these processes to improve cell survival and repair, and the importance of these processes at different levels of biological organization. The physics of shock wave creation has been modeled and can be used to calculate forces acting on individual neurons. By ensuring that the impulse is in the same regime as that occurring in practical TBI, the LIS model can ensure that in vitro conditions and damage are similar to those experienced in TBI. This model will allow for the study of the biochemical response of neurons to mechanical stresses, and can be combined with microfluidic systems for cell growth in order to better isolate areas of damage.

  2. Laser-induced grating spectroscopy of cadmium telluride

    Science.gov (United States)

    Petrovic, Mark S.; Suchocki, Andrzej; Powell, Richard C.; Cantwell, Gene; Aldridge, Jeff

    1989-08-01

    Laser-induced transient gratings produced by two-photon absorption of picosecond pulses at 1.064 μm were used to examine the room-temperature nonlinear optical responses of CdTe crystals with different types of conductivity. Pulse-probe degenerate four-wave mixing measurements of grating dynamics on subnanosecond time scales were used to measure the ambipolar diffusion coefficient (Da) of charge carriers in the crystals. The value of Da =3.0 cm2 s-1 which was obtained is in very good agreement with theoretical estimates. A long-lived contribution to the signal consistent with a trapped charge photorefractive effect was observed at large grating spacings for n-type conductivity, and is tentatively attributed to a larger trap density in this sample. Measurements of the relative scattering efficiencies of successive diffracted orders in the Raman-Nath regime allowed for calculation of the laser-induced change in the index of refraction, due to the creation of free carriers. The value of Δn=4×10-4 which was obtained is in good agreement with theoretical estimates.

  3. Laser-induced breakdown spectroscopy of tantalum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

    2013-07-15

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  4. Laser induced breakdown spectroscopy inside liquids: Processes and analytical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Lazic, V., E-mail: violeta.lazic@enea.it [ENEA (UTAPRAD-DIM), Via. E. Fermi 45, 00044 Frascati (RM) (Italy); Jovićević, S. [Institute of Physics, University of Belgrade, 11080 Belgrade (Serbia)

    2014-11-01

    This paper provides an overview of the laser induced breakdown spectroscopy (LIBS) inside liquids, applied for detection of the elements present in the media itself or in the submerged samples. The processes inherent to the laser induced plasma formation and evolution inside liquids are discussed, including shockwave generation, vapor cavitation, and ablation of solids. Types of the laser excitation considered here are single pulse, dual pulse and multi-pulse. The literature relative to the LIBS measurements and applications inside liquids is reviewed and the most relevant results are summarized. Finally, we discuss the analytical aspects and release some suggestions for improving the LIBS sensitivity and accuracy in liquid environment. - Highlights: • The paper reviews LIBS applications on bulk liquids and on submerged samples, using single, dual and multi pulse excitation. • The fundamentals about plasma in liquids are provided: beam transmission, breakdown, ablation, cavitation, and energy balance • Influence of the bubble’s optical properties on the plasma formation and detection after the second pulse is considered • The results obtained by various research groups and in different experimental conditions are reviewed and summarized • The analytical aspects are discussed, which include the experimental part, signal stability, data processing and calibration.

  5. Laser induced breakdown spectroscopy inside liquids: Processes and analytical aspects

    International Nuclear Information System (INIS)

    This paper provides an overview of the laser induced breakdown spectroscopy (LIBS) inside liquids, applied for detection of the elements present in the media itself or in the submerged samples. The processes inherent to the laser induced plasma formation and evolution inside liquids are discussed, including shockwave generation, vapor cavitation, and ablation of solids. Types of the laser excitation considered here are single pulse, dual pulse and multi-pulse. The literature relative to the LIBS measurements and applications inside liquids is reviewed and the most relevant results are summarized. Finally, we discuss the analytical aspects and release some suggestions for improving the LIBS sensitivity and accuracy in liquid environment. - Highlights: • The paper reviews LIBS applications on bulk liquids and on submerged samples, using single, dual and multi pulse excitation. • The fundamentals about plasma in liquids are provided: beam transmission, breakdown, ablation, cavitation, and energy balance • Influence of the bubble’s optical properties on the plasma formation and detection after the second pulse is considered • The results obtained by various research groups and in different experimental conditions are reviewed and summarized • The analytical aspects are discussed, which include the experimental part, signal stability, data processing and calibration

  6. Microwave assisted laser-induced breakdown spectroscopy at ambient conditions

    Science.gov (United States)

    Viljanen, Jan; Sun, Zhiwei; Alwahabi, Zeyad T.

    2016-04-01

    Signal enhancements in laser-induced breakdown spectroscopy (LIBS) using external microwave power are demonstrated in ambient air. Pulsed microwave at 2.45 GHz and of 1 millisecond duration was delivered via a simple near field applicator (NFA), with which an external electric field is generated and coupled into laser induced plasma. The external microwave power can significantly increase the signal lifetime from a few microseconds to hundreds of microseconds, resulting in a great enhancement on LIBS signals with the use of a long integration time. The dependence of signal enhancement on laser energy and microwave power is experimentally assessed. With the assistance of microwave source, a significant enhancement of ~ 100 was achieved at relatively low laser energy that is only slightly above the ablation threshold. A limit of detection (LOD) of 8.1 ppm was estimated for copper detection in Cu/Al2O3 solid samples. This LOD corresponds to a 93-fold improvement compared with conventional single-pulse LIBS. Additionally, in the microwave assisted LIBS, the self-reversal effect was greatly reduced, which is beneficial in measuring elements of high concentration. Temporal measurements have been performed and the results revealed the evolution of the emission process in microwave-enhanced LIBS. The optimal position of the NFA related to the ablation point has also been investigated.

  7. Laser-induced breakdown spectroscopy of tantalum plasma

    International Nuclear Information System (INIS)

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO2: N2: He), O2, N2, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis

  8. [Identification of invoice based on laser-induced photoluminescence spectrum].

    Science.gov (United States)

    Yang, Qin; Yang, Yong; Tian, Yong-hong

    2011-12-01

    The rapid identification of invoice authenticity was studied based on laser-induced photoluminescence spectrum. First, the spectral curves of eighty invoice samples were obtained by laser-induced photoluminescence detection system, and genetic algorithm (GA) was applied to fit and separate overlapped spectral region between 566 and 669 nm by three Gaussian peaks. Spectral feature parameters extracted by GA were employed as the inputs of BP neural networks, and then an identification model was built. One hundred and four data were converted to 13 Gaussian parameters, and for authentic and false invoices the coefficients of determination (R2) were 0.99789 and 0.99683 and the relative standard deviations (RSD) were 0.017052 and 0.022362, respectively. It was showed that Gaussian fitting algorithm could not only simplify the parameters of models, but also improve the explanation of analysis models. Through comparison analysis of the results, it was found that the model, whose thirteen feature parameters and two evaluated parameters were all applied as BP inputs, was the best, and the corrected identification rates of sixty calibration samples and twenty validation samples were both 100%. So the identification method studied in the present research played a good role in the classification and identification, and offered a new approach to the rapid identification of invoice authenticity. PMID:22295788

  9. Direct probing of chromatography columns by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.

    1992-12-07

    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  10. Detection of explosives with laser-induced breakdown spectroscopy

    Science.gov (United States)

    Wang, Qian-Qian; Liu, Kai; Zhao, Hua; Ge, Cong-Hui; Huang, Zhi-Wen

    2012-12-01

    Our recent work on the detection of explosives by laser-induced breakdown spectroscopy (LIBS) is reviewed in this paper. We have studied the physical mechanism of laser-induced plasma of an organic explosive, TNT. The LIBS spectra of TNT under single-photon excitation are simulated using MATLAB. The variations of the atomic emission lines intensities of carbon, hydrogen, oxygen, and nitrogen versus the plasma temperature are simulated too. We also investigate the time-resolved LIBS spectra of a common inorganic explosive, black powder, in two kinds of surrounding atmospheres, air and argon, and find that the maximum value of the O atomic emission line SBR of black powder occurs at a gate delay of 596 ns. Another focus of our work is on using chemometic methods such as principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) to distinguish the organic explosives from organic materials such as plastics. A PLS-DA model for classification is built. TNT and seven types of plastics are chosen as samples to test the model. The experimental results demonstrate that LIBS coupled with the chemometric techniques has the capacity to discriminate organic explosive from plastics.

  11. Flare up of choroiditis and choroidal neovasculazation associated with punctate inner choroidopathy during early pregnancy

    Directory of Open Access Journals (Sweden)

    Rao Vinita

    2011-01-01

    Full Text Available A 28-year-old, healthy female, who had a recent repeated history of miscarriage, presented with bilateral choroidal neovascular membranes (CNVM, for which she received photodynamic therapy with three doses of lucentis, at intervals of one month each, to which she responded. After five months, the patient again presented with complaints of diminution of vision since 15 days. She had a history of miscarriage two days before presenting to our clinic. CNVM was scarred at this time and the fundus picture showed multiple small punctate spots around the fovea at the level of the choroid, which showed early hyperfluroscence on fundus fluorescein angiography, suggestive of punctate inner choroidopathy. She was advised systemic steroids, to which she responded dramatically.

  12. Action Research for Poverty Alleviation

    OpenAIRE

    D. Rajasekhar

    2002-01-01

    This paper documents the process adopted in an action research project for poverty alleviation undertaken in two project areas of NGOs. After describing the process adopted to initiate action research, the paper discusses the methods conducted to acquire knowledge on processes generating poverty, and strategies adopted to alleviate poverty both by the poor and local organisations. Methods adopted to translate the knowledge into action are also discussed. Conclusions are provided at the end.

  13. Age-based analysis of choroidal thickness and choroidal vessel diameter in primary open-angle glaucoma.

    Science.gov (United States)

    Toprak, Ibrahim; Yaylalı, Volkan; Yildirim, Cem

    2016-04-01

    We aimed to assess choroidal thickness and vessel diameter in patients with primary open-angle glaucoma (POAG) using enhanced depth imaging (EDI) optical coherence tomography (OCT) with age-based analysis. Fifty-four patients with a confirmed diagnosis of POAG and 44 age-sex matched healthy subjects were included into the study. A masked physician performed measurements of largest choroidal vessel diameter and choroidal thicknesses (subfoveal, nasal, and temporal) using EDI OCT. Subgroup analyses were performed to compare choroidal measurements based on age (with a cut point of 70 years). The study cohort comprised 54 patients with POAG (mean age of 63.2 ± 8.8 years) and 44 healthy control subjects (mean age of 62.9 ± 8.5 years) (P = 0.870). We found no significant differences in terms of choroidal measurements (P > 0.05) between the glaucoma and control groups. However, in the glaucoma group, patients with an age ≥70 years had significantly thinner subfoveal and nasal choroid compared to those of the patients with  0.05). Choroidal thickness and vessel caliber seem not to differ between patients with POAG and healthy controls. However, an age ≥70 years might be associated with thinning in subfoveal and nasal choroid in patients with POAG. Further studies are needed to elucidate whether choroidal thinning is a cause or result in POAG. PMID:26077882

  14. Role of Intravitreal Antivascular Endothelial Growth Factor Injections for Choroidal Neovascularization due to Choroidal Osteoma

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour

    2014-01-01

    Full Text Available We treated 26 eyes of 25 young patients having a mean age of 30 years with intravitreal vascular endothelial growth factor (VEGF inhibitor for choroidal new vessel (CNV formation overlying choroidal osteoma over a mean follow-up of 26 months. Mean number of injections was 2.4 at 6 months, 3.2 at 12 months, and 5.5 at 24 months. CNV was subfoveal in 14 eyes, juxtafoveal in 5, extrafoveal in 5, and peripapillary in 2. By paired comparison, mean decrease from baseline was 119.7 microns at 6 months (n=15; P=0.001, 105.3 microns at 1 year (n=10; P=0.03, and 157.6 microns at 2 years (n=7; P=0.08. BCVA improved by 3.3 lines at 6 months after therapy (n=26; P<0.001, 2.8 lines (n=20; P=0.01 at 1 year, and 3.1 lines (n=13; P=0.049 at 2 years. We conclude that intravitreal anti-VEGF injections improve vision in majority of eyes with CNV from choroidal osteoma.

  15. Role of Intravitreal Antivascular Endothelial Growth Factor Injections for Choroidal Neovascularization due to Choroidal Osteoma

    Science.gov (United States)

    Mansour, Ahmad M.; Al Kahtani, Eman; Zegarra, Hernando; Anand, Rajiv; Ahmadieh, Hamid; Sisk, Robert A.; Mirza, Salman; Tuncer, Samuray; Navea Tejerina, Amparo; Mataix, Jorge; Ascaso, Francisco J.; Pulido, Jose S.; Guthoff, Rainer; Goebel, Winfried; Roh, Young Jung; Banker, Alay S.; Gentile, Ronald C.; Martinez, Isabel Alonso; Morris, Rodney; Panday, Neeraj; Min, Park Jung; Mercé, Emilie; Lai, Timothy Y. Y.; Massoud, Vicky; Ghazi, Nicola G.

    2014-01-01

    We treated 26 eyes of 25 young patients having a mean age of 30 years with intravitreal vascular endothelial growth factor (VEGF) inhibitor for choroidal new vessel (CNV) formation overlying choroidal osteoma over a mean follow-up of 26 months. Mean number of injections was 2.4 at 6 months, 3.2 at 12 months, and 5.5 at 24 months. CNV was subfoveal in 14 eyes, juxtafoveal in 5, extrafoveal in 5, and peripapillary in 2. By paired comparison, mean decrease from baseline was 119.7 microns at 6 months (n = 15; P = 0.001), 105.3 microns at 1 year (n = 10; P = 0.03), and 157.6 microns at 2 years (n = 7; P = 0.08). BCVA improved by 3.3 lines at 6 months after therapy (n = 26; P < 0.001), 2.8 lines (n = 20; P = 0.01) at 1 year, and 3.1 lines (n = 13; P = 0.049) at 2 years. We conclude that intravitreal anti-VEGF injections improve vision in majority of eyes with CNV from choroidal osteoma. PMID:25147732

  16. Effects of pulse width on nascent laser-induced bubbles for underwater laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    The reason for the significant advantage offered by long-pulse (150 ns) irradiation in underwater laser-induced breakdown spectroscopy (LIBS) is investigated from the point of view of the behavior of nascent cavitation bubbles. Shadowgraphs of nascent bubbles generated by pulsed laser irradiation of Cu targets in water were observed for two different pulse widths, 20 ns and 150 ns. It is clearly seen that the nascent bubble is formed at the leading edge of the laser pulse profile, regardless of the pulse width. Bubbles generated by a 20-ns pulse are characterized by a flat-shape filled with dense matter with intense optical emission, which is in contrast to more hemispherical low-density bubbles observed under the irradiation by a 150-ns pulse. The behavior of the nascent bubbles is consistent with the behavior of the later plasma in the bubbles, which is crucial for observation of well-defined atomic spectral lines for underwater LIBS. - Highlights: • We observed laser-induced cavitation bubbles in very high time resolution. • Nascent bubbles are found to be generated at leading edge of the laser pulse. • Features of the nascent bubbles depend on the pulse width. • The reason for the advantage of long-pulse irradiation in underwater LIBS is clarified

  17. Gelsolin Restores Aβ-Induced Alterations in Choroid Plexus Epithelium

    Directory of Open Access Journals (Sweden)

    Teo Vargas

    2010-01-01

    Full Text Available Histologically, Alzheimer's disease (AD is characterized by senile plaques and cerebrovascular amyloid deposits. In previous studies we demonstrated that in AD patients, amyloid-β (Aβ peptide also accumulates in choroid plexus, and that this process is associated with mitochondrial dysfunction and epithelial cell death. However, the molecular mechanisms underlying Aβ accumulation at the choroid plexus epithelium remain unclear. Aβ clearance, from the brain to the blood, involves Aβ carrier proteins that bind to megalin, including gelsolin, a protein produced specifically by the choroid plexus epithelial cells. In this study, we show that treatment with gelsolin reduces Aβ-induced cytoskeletal disruption of blood-cerebrospinal fluid (CSF barrier at the choroid plexus. Additionally, our results demonstrate that gelsolin plays an important role in decreasing Aβ-induced cytotoxicity by inhibiting nitric oxide production and apoptotic mitochondrial changes. Taken together, these findings make gelsolin an appealing tool for the prophylactic treatment of AD.

  18. Keratoconus associated with choroidal neovascularization: a case report

    Directory of Open Access Journals (Sweden)

    Oh Joo

    2010-02-01

    Full Text Available Abstract Introduction Keratoconus and choroidal neovascularization can occur as a result of dysfunction of the epithelium and its basement membrane. Case presentation A 17-year-old Asian man, who was diagnosed with myopic choroidal neovascularization in both eyes and who subsequently underwent intravitreal injection of ranibizumab (Lucentis® five times over six months, presented with further vision decrease and pain in his right eye. Examination showed corneal steepening and stromal edema in the inferocentral cornea of his right eye, both of which were indicative of advanced keratoconus with acute hydrops. Corneal topography also showed features consistent with keratoconus in his left eye. Fluorescein angiography and optical coherence tomography revealed choroidal neovascularization-associated subretinal hemorrhages and lacquer cracks in both eyes. Conclusion Keratoconus and choroidal neovascularization, possibly resulting from dysfunction of the epithelium and its basement membrane, can occur together in the same individual. This would suggest a possible connection in pathogenesis between these two conditions.

  19. Morphological features of choroidal metastases: An OCT analysis

    Directory of Open Access Journals (Sweden)

    Ludovico Iannetti

    2013-01-01

    Full Text Available The morphological characteristics and retinal changes of chroidal metastases using Spectral Domain OCT are described in a case with primary lung adenocarcinoma and secondary choroidal involvement.

  20. Treatment of choroidal neovascularization in high myopia.

    Science.gov (United States)

    Montero, Javier A; Ruiz-Moreno, Jose M

    2010-05-01

    High myopia affects approximately 2% of general population, and is a major cause of legal blindness in many developed countries. Choroidal neovascularization (CNV) is the most common vision-threatening complication of high myopia. Different therapeutic approaches have been attempted such as thermal laser photocoagulation, surgery and photodynamic therapy with verteporfin (PDT). The visual outcome of these therapies has been reported to be better than the natural history of the condition. However, the limited visual acuity improvement after PDT monotherapy and the appearance of subretinal fibrosis and chorioretinal atrophy prompted the association of other therapies. In the past few years a tremendous advance in the knowledge of the mechanisms underling CNV secondary to high myopia and age related macular degeneration has been achieved, leading to new therapeutic targets and novel drugs and combined therapies. These new therapeutic weapons have been designed to achieve a selective shut down of choroidal new vessels. Recent reviews have been published on the natural history and therapies for myopic CNV. Ohno-Matsui reported on the natural history of the condition as well as the outcome of laser photocoagulation, surgical extraction of CNV, foveal translocation and photodynamic therapy on myopic CNV in the short-term. Soubrane et al reviewed the new advances on surgery, laser photocoagulation and PDT, considering some of the potential effects of triamcinolone, pegaptanib and ranibizumab in CNV secondary to age related macular degeneration (AMD). Novack et al reported on the pharmacological therapy of CNV in AMD. The aim of this review is to summarize the recent advances in myopic CNV pathophysiology and the new therapeutic targets and drugs that are changing the clinical management of myopic CNV. PMID:20196722

  1. Review on the laser-induced damage mechanism study of photoelectric detectors

    International Nuclear Information System (INIS)

    The author reviews that the various reported laser-induced effects on the photoelectric detectors and their composed material. It collects all kinds of thresholds of shape damage and electricity damage systematically, and analyzes these cases contrastive. At the same time several kinds of the laser-induced damage mechanism and their theoretical models are discussed

  2. Laser-Induced Fluorescence in Gaseous [I[subscript]2] Excited with a Green Laser Pointer

    Science.gov (United States)

    Tellinghuisen, Joel

    2007-01-01

    A green laser pointer could be used in a flashy demonstration of laser-induced fluorescence in the gas phase by directing the beam of the laser through a cell containing [I[subscript]2] at its room temperature vapor pressure. The experiment could be used to provide valuable insight into the requirements for laser-induced fluorescence (LIF) and the…

  3. SOME PROPERTIES OF ATOMIC BEAM PRODUCED BY LASER INDUCED ABLATION OF Li TARGET

    OpenAIRE

    Harnafi, M.; Dubreuil, B.

    1987-01-01

    In this experiment, pulsed atomic beams produced in vacuum by laser induced ablation from lithium target are analyzed by laser-induced fluorescsence (LIF). As an application of this atomic beam production technique, the l-mixing processes induced in the n = 9, 10 Li Rydberg states by collisions with CO2 molecules have been investigated.

  4. Laser induced extraplanar propulsion for three-dimensional microfabrication

    International Nuclear Information System (INIS)

    The laser induced extraplanar propulsion process is presented for the creation of controllable three-dimensional deformation of on-substrate components. It is demonstrated that the process is compatible with transparent substrates and ductile materials and is highly controllable in terms of the desired deformation via the adjustment of incident laser energy density. Copper films with thicknesses varying from 0.1-1 μm are deformed over bending angles ranging from 0 deg. - 180 deg. A 355 nm laser at fluences ranging from 10-40 mJ/cm2 is used in conjunction with an indium-tin-oxide propulsion layer to demonstrate the process. Characterization is performed via electron and laser confocal microscopy.

  5. Thomson scattering from laser induced plasma in air

    Energy Technology Data Exchange (ETDEWEB)

    Dzierzega, K; Mendys, A [Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Pellerin, S; Thouin, E [GREMI - site de Bourges, Universite d' Orleans, rue Gaston Berger BP 4043, 18028 Bourges (France); Travaille, G; Bousquet, B; Canioni, L [Centre de Physique Moleculaire Optique et Hertzienne, Universite Bordeaux I, 351 Cours de la Liberation, 33405 Talence CEDEX (France); Pokrzywka, B, E-mail: krzysztof.dzierzega@uj.edu.p [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland)

    2010-05-01

    The laser induced plasma in air produced by 6 ns, 532 nm Nd:YAG pulses with 25 mJ energy was studied using the Thomson scattering method and plasma imaging techniques. Plasma images and Thomson scattered spectra were registered at delay times ranging from 150 ns to 1 {mu}s after the breakdown pulses. The electron density and temperature, as determined in the core of the plasma plume, were found to decrease from 7.4 x 10{sup 17} cm{sup -3} to about 1.03 x 10{sup 17} cm{sup -3} and from 100 900 K to 22 700 K. The highly elevated electron temperatures are the result of plasma heating by the second, probe pulse in the Thomson scattering experiments.

  6. Thomson scattering from laser induced plasma in air

    International Nuclear Information System (INIS)

    The laser induced plasma in air produced by 6 ns, 532 nm Nd:YAG pulses with 25 mJ energy was studied using the Thomson scattering method and plasma imaging techniques. Plasma images and Thomson scattered spectra were registered at delay times ranging from 150 ns to 1 μs after the breakdown pulses. The electron density and temperature, as determined in the core of the plasma plume, were found to decrease from 7.4 x 1017 cm-3 to about 1.03 x 1017 cm-3 and from 100 900 K to 22 700 K. The highly elevated electron temperatures are the result of plasma heating by the second, probe pulse in the Thomson scattering experiments.

  7. Laser-induced atomic adsorption: a mechanism for nanofilm formation

    CERN Document Server

    Martins, Weliton S; Oriá, Marcos; Chevrollier, Martine

    2013-01-01

    We demonstrate and interpret a technique of laser-induced formation of thin metallic films using alkali atoms on the window of a dense-vapour cell. We show that this intriguing photo-stimulated process originates from the adsorption of Cs atoms via the neutralisation of Cs$^+$ ions by substrate electrons. The Cs$^+$ ions are produced via two-photon absorption by excited Cs atoms very close to the surface, which enables the transfer of the laser spatial intensity profile to the film thickness. An initial decrease of the surface work function is required to guarantee Cs$^+$ neutralisation and results in a threshold in the vapour density. This understanding of the film growth mechanism may facilitate the development of new techniques of laser-controlled lithography, starting from thermal vapours.

  8. Laser-induced micro-jetting from armored droplets

    KAUST Repository

    Marston, J. O.

    2015-06-23

    We present findings from an experimental study of laser-induced cavitation within a liquid drop coated with a granular material, commonly referred to as “armored droplets” or “liquid marbles.” The cavitation event follows the formation of plasma after a nanosecond laser pulse. Using ultra-high-speed imaging up to 320,610 fps, we investigate the extremely rapid dynamics following the cavitation, which manifests itself in the form of a plethora of micro-jets emanating simultaneously from the spaces between particles on the surface of the drop. These fine jets break up into droplets with a relatively narrow diameter range, on the order of 10 μm. © 2015, Springer-Verlag Berlin Heidelberg.

  9. Diagnostics of laser-induced plasma by optical emission spectroscopy

    International Nuclear Information System (INIS)

    The procedure for diagnostics of laser induced plasma (LIP) by optical emission spectroscopy technique is described. LIP was generated by focusing Nd:YAG laser radiation (1.064 nm, 50 mJ, 15 ns pulse duration) on the surface of pellet containing among other elements lithium. Details of the experimental setup and experimental data processing are presented. High speed plasma photography was used to study plasma evolution and decay. From those images optimum time for plasma diagnostics is located. The electron number density, Ne, is determined by fitting profiles of Li I lines while electron temperature, Te, was determined from relative intensities of Li I lines using Boltzmann plot (BP) technique. All spectral line recordings were tested for the presence of self-absorption and then if optically thin, Abel inverted and used for plasma diagnostic purposes

  10. Laser-induced breakdown spectroscopy fundamentals and applications

    CERN Document Server

    Noll, Reinhard

    2012-01-01

    This book is a comprehensive source of the fundamentals, process parameters, instrumental components and applications of laser-induced breakdown spectroscopy (LIBS). The effect of multiple pulses on material ablation, plasma dynamics and plasma emission is presented. A heuristic plasma modeling allows to simulate complex experimental plasma spectra. These methods and findings form the basis for a variety of applications to perform quantitative multi-element analysis with LIBS. These application potentials of LIBS have really boosted in the last years ranging from bulk analysis of metallic alloys and non-conducting materials, via spatially resolved analysis and depth profiling covering measuring objects in all physical states: gaseous, liquid and solid. Dedicated chapters present LIBS investigations for these tasks with special emphasis on the methodical and instrumental concepts as well as the optimization strategies for a quantitative analysis. Requirements, concepts, design and characteristic features of LI...

  11. Femtosecond laser induced phenomena in transparent solid materials

    DEFF Research Database (Denmark)

    Tan, D.Z.; Sharafudeen, K.N.; Yue, Yuanzheng;

    2016-01-01

    the art in studying femtosecond laser induced various phenomena in transparent materials, including their physical and chemical mechanisms, the applications and limitations as well as the future research trends. The first part of the review presents the basics of femtosecond laser systems, important......The interaction of intense femtosecond laser pulses with transparent materials is a topic that has caused great interest of scientists over the past two decades. It will continue to be a fascinating field in the coming years. This is because many challenging fundamental problems have not been...... solved, especially concerning the interaction of strong, ultra-short electromagnetic pulses with matter, and also because potential advanced technologies will emerge due to the impressive capability of the intense femtosecond laser to create new material structures and hence functionalities. When...

  12. A Spectral Analysis of Laser Induced Fluorescence of Iodine

    CERN Document Server

    Bayram, S B

    2015-01-01

    When optically excited, iodine absorbs in the 490- to 650-nm visible region of the spectrum and, after radiative relaxation, it displays an emission spectrum of discrete vibrational bands at moderate resolution. This makes laser-induced fuorescence spectrum of molecular iodine especially suitable to study the energy structure of homonuclear diatomic molecules at room temperature. In this spirit, we present a rather straightforward and inexpensive experimental setup and the associated spectral analysis which provides an excellent exercise of applied quantum mechanics fit for advanced laboratory courses. The students would be required to assign spectral lines, fill a Deslandres table, process the data to estimate the harmonic and anharmonic characteristics of the ground vibronic state involved in the radiative transitions, and thenceforth calculate a set of molecular constants and discuss a model of molecular vibrator.

  13. Laser induced changes of refractive index of lead - silicate glasses

    International Nuclear Information System (INIS)

    The mechanisms of photoinduced changes of refractive index of the TΦ lead - silicate glasses (analogous with the SF glasses from Schott catalog) under the effect of high power laser radiation with quantum energy less bandgap have been studied. It is shown that the laser induced color centers results in increase of refractive index into the exposed bulk during the laser pulse action. This leads to considerable redistribution of irradiance and decrease of laser radiation brightness even in the case of optical elements less 1 mm thickness. The observed effect may be connected both with radiation induced dilatation of matter and heating of interaction region owing to absorption of radiation by color centers. Comparison the kinetics of refractive index change of the glass after exposure by laser pulse at 0.53 μm and the kinetics of color centers decay allowed to draw a conclusion about heat character of observed changes

  14. Hydrogen retention in tungsten materials studied by Laser Induced Desorption

    Science.gov (United States)

    Zlobinski, M.; Philipps, V.; Schweer, B.; Huber, A.; Reinhart, M.; Möller, S.; Sergienko, G.; Samm, U.; 't Hoen, M. H. J.; Manhard, A.; Schmid, K.; Textor Team

    2013-07-01

    Development of methods to characterise the first wall in ITER and future fusion devices without removal of wall tiles is important to support safety assessments for tritium retention and dust production and to understand plasma wall processes in general. Laser based techniques are presently under investigation to provide these requirements, among which Laser Induced Desorption Spectroscopy (LIDS) is proposed to measure the deuterium and tritium load of the plasma facing surfaces by thermal desorption and spectroscopic detection of the desorbed fuel in the edge of the fusion plasma. The method relies on its capability to desorb the hydrogen isotopes in a laser heated spot. The application of LID on bulk tungsten targets exposed to a wide range of deuterium fluxes, fluences and impact energies under different surface temperatures is investigated in this paper. The results are compared with Thermal Desorption Spectrometry (TDS), Nuclear Reaction Analysis (NRA) and a diffusion model.

  15. Detection of early caries by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-07-01

    To improve sensitivity of dental caries detection by laser-induced breakdown spectroscopy (LIBS) analysis, it is proposed to utilize emission peaks in the ultraviolet. We newly focused on zinc whose emission peaks exist in ultraviolet because zinc exists at high concentration in the outer layer of enamel. It was shown that by using ratios between heights of an emission peak of Zn and that of Ca, the detection sensitivity and stability are largely improved. It was also shown that early caries are differentiated from healthy part by properly setting a threshold in the detected ratios. The proposed caries detection system can be applied to dental laser systems such as ones based on Er:YAG-lasers. When ablating early caries part by laser light, the system notices the dentist that the ablation of caries part is finished. We also show the intensity of emission peaks of zinc decreased with ablation with Er:YAG laser light.

  16. Laser induced bunch lengthening on the ACO storage ring FEL

    Science.gov (United States)

    Robinson, K. E.; Madey, J. M. J.; Deacon, D. A. G.; Velghe, M. F.

    1983-03-01

    The experimental procedures and data obtained during a study of the laser-induced change in the electron bunch length are reported for trials with a free-electron laser (FEL). Bunch lengthening is thought to play a critical role in the efficiency and power output of an FEL. The experimental apparatus consisted of an external laser, an undulator ring, and a nonisochronous storage ring. Synchrotron light in the storage ring was measured by a photodiode, and bunch length changes were monitored by tuning the receiver mode to a harmonic of the orbit frequency. A Gaussian electron pulse shape was assumed, together with a Gaussian envelope for the Fourier transform, which was proven in a previous experiment. The power spectra of the photodiode were modeled analytically. It was found that high current conditions alter the electron excitation and require further theoretical modeling.

  17. Nanocrystalline silicon films prepared by laser-induced crystallization

    Institute of Scientific and Technical Information of China (English)

    傅广生; 于威; 李社强; 侯海虹; 彭英才; 韩理

    2003-01-01

    The excimer laser-induced crystallization technique has been used to investigate the preparation of nanocrystalline silicon (nc-Si) from amorphous silicon (α-Si) thin films on silicon or glass substrates. The α-Si films without hydrogen grown by pulsed-laser deposition are chosen as precursor to avoid the problem of hydrogen effluence during annealing.Analyses have been performed by scanning electron microscopy, atomic force microscopy, Raman scattering spectroscopy and high-resolution transmission-electron microscopy. Experimental results show that silicon nanocrystals can be formed through laser annealing. The growth characters of nc-Si are strongly dependent on the laser energy density. It is shown that the volume of the molten silicon predominates essentially the grain size of nc-Si, and the surface tension of the crystallized silicon is responsible for the mechanism of nc-Si growth.

  18. Laser-induced break-up of water jet waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Couty, P.; Hoffmann, P. [EPFL/STI/IOA/Advanced Photonics Laboratory, Lausanne BM, 1015, Lausanne (Switzerland); Spiegel, A.; Vago, N. [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111, Budapest (Hungary); Ugurtas, B.I. [EPFL/STI/IMHEF/Laboratory Fluid Mechanics, Lausanne, 1015, Lausanne (Switzerland)

    2004-06-01

    In this article, an optical method to control the break-up of high-speed liquid jets is proposed. The method consists of focusing the light of a pulsed laser source into the jet behaving as a waveguide. Experiments were performed with the help of a Q-switched frequency doubled Nd:Yag laser ({lambda}=532 nm). The jet diameter was 48 {mu}m and jet velocities from 100 to 200 m/s. To study the laser-induced water jet break-up, observations of the jet coupled with the high power laser were performed for variable coupling and jet velocity conditions. Experimentally determined wavelength and growth rate of the laser-generated disturbance were also compared with the ones predicted by linear stability theory of free jets. (orig.)

  19. Microfabrication of Fresnel zone plates by laser induced solid ablation

    Science.gov (United States)

    Rodrigues, Vanessa R. M.; Thomas, John; Santhosh, Chidangil; Ramachandran, Hema; Mathur, Deepak

    2016-07-01

    A novel and simple single-step method of inscribing optical elements on metal-coated transparent substrates is demonstrated. Laser induced solid ablation (LISA) demands very low laser energies (nJ), as can be amply provided by a femtosecond laser oscillator. Here, LISA is used to write Fresnel zone plates on indium and tungsten coated glass. With up to 100 zones, remarkable agreement is obtained between measured and expected values of the focal length. LISA has enabled attainment of focal spot sizes that are 38% smaller than what would be obtained using conventional lenses of the same numerical aperture. The simplicity with which a high degree of automation can readily be achieved using LISA makes this cost-effective method amenable to a wide variety of applications related to microfabrication of optical elements.

  20. Laser induced sonofusion: A new road toward thermonuclear reactions

    Science.gov (United States)

    Sadighi-Bonabi, Rasoul; Gheshlaghi, Maryam

    2016-03-01

    The Possibility of the laser assisted sonofusion is studied via single bubble sonoluminescence (SBSL) in Deuterated acetone (C3D6O) using quasi-adiabatic and hydro-chemical simulations at the ambient temperatures of 0 and -28.5 °C. The interior temperature of the produced bubbles in Deuterated acetone is 1.6 × 106 K in hydro-chemical model and it is reached up to 1.9 × 106 K in the laser induced SBSL bubbles. Under these circumstances, temperature up to 107 K can be produced in the center of the bubble in which the thermonuclear D-D fusion reactions are promising under the controlled conditions.

  1. Laser induced sonofusion: A new road toward thermonuclear reactions

    Directory of Open Access Journals (Sweden)

    Rasoul Sadighi-Bonabi

    2016-03-01

    Full Text Available The Possibility of the laser assisted sonofusion is studied via single bubble sonoluminescence (SBSL in Deuterated acetone (C3D6O using quasi-adiabatic and hydro-chemical simulations at the ambient temperatures of 0 and −28.5 °C. The interior temperature of the produced bubbles in Deuterated acetone is 1.6 × 106 K in hydro-chemical model and it is reached up to 1.9 × 106 K in the laser induced SBSL bubbles. Under these circumstances, temperature up to 107 K can be produced in the center of the bubble in which the thermonuclear D-D fusion reactions are promising under the controlled conditions.

  2. Kinetic analysis of pulsed laser induced phosphorescence for uranium determination

    International Nuclear Information System (INIS)

    The laser induced kinetic phosphorescence allows the uranium determination in different kind of matrices, with a lower detection limit than those reached by other spectroscopic methods. It involves the uranyl ions excitation by a pulsed dye-laser source, followed by temporal resolution of the phosphorescence. This method is used for the determination of trace quantities of uranium in aqueous solution, with a suitable complexant agent, without chemical separation before the analysis. The objective of this paper is to present the results of uranium determinations in different standard samples, water, soil, filter and urine, and a comparison with other methods such as fluorimetry, alpha spectrometry and mass spectrometry. Moreover, the measurement conditions, the advantages and disadvantages, the sample preparation, the interferences and the detection limit are described. (author)

  3. Inexpensive laser-induced surface modification in bismuth thin films

    International Nuclear Information System (INIS)

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters

  4. Laser-induced single point nanowelding of silver nanowires

    Science.gov (United States)

    Dai, Shuowei; Li, Qiang; Liu, Guoping; Yang, Hangbo; Yang, Yuanqing; Zhao, Ding; Wang, Wei; Qiu, Min

    2016-03-01

    Nanowelding of nanomaterials opens up an emerging set of applications in transparent conductors, thin-film solar cells, nanocatalysis, cancer therapy, and nanoscale patterning. Single point nanowelding (SPNW) is highly demanded for building complex nanostructures. In this letter, the precise control of SPNW of silver nanowires is explored in depth, where the nanowelding is laser-induced through the plasmonic resonance enhanced photothermal effect. It is shown that the illumination position is a critical factor for the nanowelding process. As an example of performance enhancement, output at wire end can be increased by 65% after welding for a plasmonic nanocoupler. Thus, single point nanowelding technique shows great potentials for high-performance electronic and photonic devices based on nanowires, such as nanoelectronic circuits and plasmonic nanodevices.

  5. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  6. Laser-induced fluorescence measurements for plasma processing

    Energy Technology Data Exchange (ETDEWEB)

    McWilliams, R. [Department of Physics and Astronomy, University of California, Irvine, CA (United States)]. E-mail: mcw@uci.edu; Boehmer, H. [Department of Physics and Astronomy, University of California, Irvine, CA (United States); Edrich, D. [Department of Physics and Astronomy, University of California, Irvine, CA (United States); Zhao, L. [Department of Physics and Astronomy, University of California, Irvine, CA (United States); Zimmerman, D. [Department of Physics and Astronomy, University of California, Irvine, CA (United States)

    2006-05-26

    Laser-induced fluorescence (LIF) has been used in plasmas for over 20 years and in plasma processing for about 10 years. Complexity and expense of this non-invasive diagnostic have limited it to laboratories although diode lasers offer hope for real-time processing metrology. LIF offers time- and space-resolved ion distribution functions, allowing study of plasma thermodynamics and transport and calibration of energy analyzers and mass flow probes. LIF was applied to an RF ion beam source (Veeco/Ion Tech). Ion distributions are compared with energy analyzer results and manufacturer's estimates. LIF distributions show narrower beam velocity spread, and better resolution, than energy analyzers. Beam ion energy can be measured rather than relying on manufacturer's estimate. Spatial resolution of LIF has permitted measurement of multidimensional ion velocity distributions in the bulk, and entering the sheath, near a conducting boundary wall.

  7. Laser induced uranium fluorescence as an analytical method

    International Nuclear Information System (INIS)

    A laser induced fluorescence system was developed to measure uranium trace level amounts in aqueous solution with reliable and simple materials and electronics. A nitrogen pulsed laser was built with the storage energy capacitor directly coupled to laser tube electrodes as a transmission line device. This laser operated at 3Hz repetition rate with peak intensity around 21 Kw and temporal width of 4.5 x 10-9 s. A sample compartment made of rigid PVC and a photomultiplier housing of aluminium were constructed and assembled forming a single integrated device. As a result of this prototype system we made several analytical measurements with U dissolved in nitric acid to obtain a calibration curve. We obtained a straight line from a plot of U concentration versus fluorescence intensity fitted by a least square method that produced a regression coefficient of 0.994. The lower limit of U determination was 30 ppb -+ 3.5%. (Author)

  8. Time evolution of laser-induced breakdown spectrometry of lead

    International Nuclear Information System (INIS)

    The plasma have been generated by a pulsed Nd: YAG laser at the fundamental wavelength of 1.06 μm ablating a metal lead target in air at atmospheric pressure, and the time resolved emission spectra were gotten. Time evolution of electron temperatures were measured according to the wavelength and relative intensity of spectra; then the electron densities were obtained from the Stark broadening of Pb-line; the time evolution of electron temperatures and electron densities along the direction plumbing the target surface were imaged. The analysis of results showed that electron temperature averaged to 14500 K, electron densities up to 1017 cm-3. The characteristics of time evolution of electron temperature and electron density were qualitatively explained from the aspect of generation mechanism of laser-induced plasmas. (authors)

  9. Controllable Femtosecond Laser-Induced Dewetting for Plasmonic Applications

    CERN Document Server

    Makarov, Sergey V; Mukhin, Ivan S; Shishkin, Ivan I; Zuev, Dmitriy A; Mozharov, Alexey M; Krasnok, Alexander E; Belov, Pavel A

    2015-01-01

    Dewetting of thin metal films is one of the most widespread method for functional plasmonic nanostructures fabrication. However, simple thermal-induced dewetting does not allow to control degree of nanostructures order without additional lithographic process steps. Here we propose a novel method for lithography-free and large-scale fabrication of plasmonic nanostructures via controllable femtosecond laser-induced dewetting. The method is based on femtosecond laser surface pattering of a thin film followed by a nanoscale hydrodynamical instability, which is found to be very controllable under specific irradiation conditions. We achieve control over degree of nanostructures order by changing laser irradiation parametrs and film thickness. This allowed us to exploit the method for the broad range of applications: resonant light absorbtion and scattering, sensing, and potential improving of thin-film solar cells.

  10. Laser induced breakdown spectroscopy for the discrimination of Candida strains.

    Science.gov (United States)

    Manzoor, S; Ugena, L; Tornero-Lopéz, J; Martín, H; Molina, M; Camacho, J J; Cáceres, J O

    2016-08-01

    The present study reports the evaluation of Laser Induced Breakdown Spectroscopy (LIBS) and Neural Networks (NN) for the discrimination of different strains of various species of Candida. This genus of yeast was selected due to its medical relevance as it is commonly found in cases of fungal infection in humans. Twenty one strains belonging to seven species of Candida were included in the study. Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS) was employed as a complementary technique to provide information about elemental composition of Candida cells. The use of LIBS spectra in combination with optimized NN models provided reliable discrimination among the distinct Candida strains with a high spectral correlation index for the samples analyzed, without any false positive or false negative. Therefore, this study indicates that LIBS-NN based methodology has the potential to be used as fast fungal identification or even diagnostic method. PMID:27216662

  11. Laser-induced incandescence: Towards quantitative soot volume fraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tzannis, A.P.; Wienbeucker, F.; Beaud, P.; Frey, H.-M.; Gerber, T.; Mischler, B.; Radi, P.P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Laser-Induced Incandescence has recently emerged as a versatile tool for measuring soot volume fraction in a wide range of combustion systems. In this work we investigate the essential features of the method. LII is based on the acquisition of the incandescence of soot when heated through a high power laser pulse. Initial experiments have been performed on a model laboratory flame. The behaviour of the LII signal is studied experimentally. By applying numerical calculations we investigate the possibility to obtain two-dimensional soot volume fraction distributions. For this purpose a combination of LII with other techniques is required. This part is discussed in some extent and the future work is outlined. (author) 4 figs., 3 refs.

  12. Hot spin spots in the laser-induced demagnetization

    Directory of Open Access Journals (Sweden)

    M. S. Si

    2012-03-01

    Full Text Available Laser-induced femtosecond magnetism or femtomagnetism simultaneously relies on two distinctive contributions: (a the optical dipole interaction (ODI between a laser field and a magnetic system and (b the spin expectation value change (SEC between two transition states. Surprisingly, up to now, no study has taken both contributions into account simultaneously. Here we do so by introducing a new concept of the optical spin generator, a product of SEC and ODI between transition states. In ferromagnetic nickel, our first-principles calculation demonstrates that the larger the value of optical spin generator is, the larger the dynamic spin moment change is. This simple generator directly links the time-dependent spin moment change ΔMzk(t at every crystal-momentum k point to its intrinsic electronic structure and magnetic properties. Those hot spin spots are a direct manifestation of the optical spin generator, and should be the focus of future research.

  13. Recognition of archaeological materials underwater by laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    The detection of different materials immersed in seawater has been studied by means of Laser Induced Breakdown Spectroscopy. The plasma emission was produced by a Q-Switched Nd:YAG laser operated at 1064 nm in a dual pulse mode. Different classes of materials potentially found in the undersea archaeological parks, such as iron, copper-based alloys, precious alloys, marble and wood have been examined. Data acquisition and processing were optimized for better signal control and in order to improve the detection threshold. In all the examined cases but wood, qualitative analysis was successful and allowed for the material recognition. The spectral features necessary to clearly distinguish marble materials from calcareous rocks have been also established. It was found that these characteristic spectral intervals could be also used for the recognition of sedimentary layers deposited on the underwater findings. Quantitative chemical analysis was also performed on submerged bronze samples, after generating calibration curves with standards of similar matrix composition

  14. Laser-induced thermoelastic effects can evoke tactile sensations

    Science.gov (United States)

    Jun, Jae-Hoon; Park, Jong-Rak; Kim, Sung-Phil; Min Bae, Young; Park, Jang-Yeon; Kim, Hyung-Sik; Choi, Seungmoon; Jung, Sung Jun; Hwa Park, Seung; Yeom, Dong-Il; Jung, Gu-In; Kim, Ji-Sun; Chung, Soon-Cheol

    2015-06-01

    Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (subjective reports of the non-nociceptive sensation of laser stimuli.

  15. Trigonometric pulse envelopes for laser-induced quantum dynamics

    International Nuclear Information System (INIS)

    We relate powers of trigonometric functions to Gaussians by proving that properly truncated cosn functions converge to a Gaussian as n tends to infinity. For an application, we analyse the laser-induced population transfer |X1Σ+) → |A1Πx) in a two-level model system of aluminium monochloride (AlCl) with fixed nuclei. We apply linearly x-polarized ultraviolet laser pulses with a trigonometric envelope function, whose square has full width at half-maximum of 2.5 fs and 5.0 fs. Studying population dynamics and optimized laser parameters, we find that the optimal field amplitude for trigonometric pulses with n = 20 and n = 1000 has a relative difference of 1%, which is below experimental resolution.

  16. Laser-induced breakdown spectroscopy theory and applications

    CERN Document Server

    Perini, Umberto

    2014-01-01

    This book deals with the Laser-Induced Breakdown Spectroscopy (LIBS), a widely used atomic emission spectroscopy technique for elemental analysis of materials. It is based on the use of a high-power, short pulse laser excitation. The book is divided into two main sections: the first one concerning theoretical aspects of the technique, the second one describing the state of the art in applications of the technique in different scientific/technological areas. Numerous examples of state of the art applications provide the readers an almost complete scenario of the LIBS technique. The LIBS theoretical aspects are reviewed. The book helps the readers who are less familiar with the technique to understand the basic principles. Numerous examples of state of the art applications give an almost complete scenario of the LIBS technique potentiality. These examples of applications may have a strong impact on future industrial utilization. The authors made important contributions to the development of this field.

  17. Femtosecond laser-induced surface structures on carbon fibers.

    Science.gov (United States)

    Sajzew, Roman; Schröder, Jan; Kunz, Clemens; Engel, Sebastian; Müller, Frank A; Gräf, Stephan

    2015-12-15

    The influence of different polarization states during the generation of periodic nanostructures on the surface of carbon fibers was investigated using a femtosecond laser with a pulse duration τ=300  fs, a wavelength λ=1025  nm, and a peak fluence F=4  J/cm². It was shown that linear polarization results in a well-aligned periodic pattern with different orders of magnitude concerning their period and an alignment parallel and perpendicular to fiber direction, respectively. For circular polarization, both types of uniform laser-induced periodic surface structures (LIPSS) patterns appear simultaneously with different dominance in dependence on the position at the fiber surface. Their orientation was explained by the polarization-dependent absorptivity and the geometrical anisotropy of the carbon fibers. PMID:26670499

  18. Thermal characterization of nanofluids using laser induced thermal lens technique

    Science.gov (United States)

    Kurian, Achamma; Kumar, Rajesh B.; George, Sajan D.

    2009-08-01

    A laser induced thermal lens technique has been employed to evaluate the dynamic thermal parameter, the thermal diffusivity, of gold nanofluids. Gold nanoparticles were synthesized by citrate reduction of HAuCl4 in water. The UVVIS optical absorption spectra show an absorption peak around 540 nm owing to surface Plasmon resonance band of the gold particles. The thermal diffusivity of gold nanoparticles was evaluated by knowing the time constant of transient thermal lens obtained by fitting the experimental curve to the theoretical model of the mode-matched thermal lens. Analyses of the results show that the nanofluid exhibits lower thermal diffusivity value in comparison to the host medium, water. Further investigations also reveal that the concentration of nanoparticles in the fluid have influence on the measured thermal diffusivity value. Results are interpreted in terms of interfacial thermal resistance around the nanoparticles as well as on the clustering of nanoparticles.

  19. Theory of laser-induced demagnetization at high temperatures

    KAUST Repository

    Manchon, Aurelien

    2012-02-17

    Laser-induced demagnetization is theoretically studied by explicitly taking into account interactions among electrons, spins, and lattice. Assuming that the demagnetization processes take place during the thermalization of the subsystems, the temperature dynamics is given by the energy transfer between the thermalized interacting baths. These energy transfers are accounted for explicitly through electron-magnon and electron-phonon interactions, which govern the demagnetization time scale. By properly treating the spin system in a self-consistent random phase approximation, we derive magnetization dynamic equations for a broad range of temperature. The dependence of demagnetization on the temperature and pumping laser intensity is calculated in detail. In particular, we show several salient features for understanding magnetization dynamics near the Curie temperature. While the critical slowdown in dynamics occurs, we find that an external magnetic field can restore the fast dynamics. We discuss the implication of the fast dynamics in the application of heat-assisted magnetic recording.

  20. Characterization of laser - induced plasmas by atomic emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Pace, Diego M; Bertuccelli, Graciela; D' Angelo, Cristian A, E-mail: ddiaz@exa.unicen.edu.ar, E-mail: gbertucc@exa.unicen.edu.ar, E-mail: cdangelo@exa.unicen.edu.ar [Instituto de Fisica ' Arroyo Seco' , Facultad de Ciencias Exactas, U.N.C.P.B.A., Campus Universitario, Paraje Arroyo Seco, (B7000GHG) Tandil, Buenos Aires (Argentina)

    2011-01-01

    In this work, Laser-induced breakdown spectroscopy (LIBS) has been applied to characterization of plasmas generated in air at atmospheric pressure from a calcium hydroxide sample with a known concentration of Mg by using an infrared Nd:YAG laser. The influence of laser irradiance on plasma morphology and emission intensity was studied. Spatially-integrated intensities of Mg I-II lines along the line-of-sight were measured for different laser energies and delay times. The plasma temperature and the electron density were determined in each case by using and algorithm that calculates the optical thickness of the spectral lines and reproduces their experimental profiles in a framework of an homogeneous plasma in LTE that takes into account the effects of self-absorption. The results obtained showed the usefulness of this approach to provide additional information retrieved from the optical thickness of spectral lines for plasma characterization in LIBS experiments.

  1. Elemental analysis of slurry samples with laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Direct analysis of wet slurry samples with laser induced breakdown spectroscopy (LIBS) is challenging due to problems of sedimentation, splashing, and surface turbulence. Also, water can quench the laser plasma and suppress the LIBS signal, resulting in poor sensitivity. The effect of water on LIBS spectra from slurries was investigated. As the water content decreased, the LIBS signal was enhanced and the standard deviation was reduced. To improve LIBS slurry analysis, dried slurry samples prepared by applying slurry on PVC coated slides were evaluated. Univariate and multivariate calibration was performed on the LIBS spectra of the dried slurry samples for elemental analysis of Mg, Si, and Fe. Calibration results show that the dried slurry samples give a good correlation between spectral intensity and elemental concentration.

  2. Enhancing Laser Induced Plasma Emissions using Various Excitation Modalities

    Science.gov (United States)

    Johnson, Lewis; Akpovo, Charlemagne; Gebreegziabher, Samson; Martinez, Jorge, Jr.

    2008-11-01

    Detection of hazardous materials with Laser Induced Breakdown Spectroscopy (LIBS) requires a detailed understanding of the sample matrix as well as the surrounding environment. We report on our efforts to understand and manipulate the continuum and atmospheric levels while enhancing surface and substrate material identifications. Comparisons are made between: single pulse (SP) nanosecond (ns); SP femtosecond (fs); SP fs-self-channeled (fs-sc); Dual pulse (DP) ns; DP ns -- fs; and DP ns fs-sc; and multi--pulse Continuous Wave (CW) plasmas formed on the sample surface. Plasma emission spectra from atmospheric oxygen and nitrogen, as well as aluminum and Copper substrates, and hazardous oxygen and nitrogen rich materials residues are analyzed.

  3. Laser-induced breakdown spectroscopy analysis of energetic materials

    Science.gov (United States)

    de Lucia, Frank C.; Harmon, Russell S.; McNesby, Kevin L.; Winkel, Raymond J.; Miziolek, Andrzej W.

    2003-10-01

    A number of energetic materials and explosives have been studied by laser-induced breakdown spectroscopy (LIBS). They include black powder, neat explosives such as TNT, PETN, HMX, and RDX (in various forms), propellants such as M43 and JA2, and military explosives such as C4 and LX-14. Each of these materials gives a unique spectrum, and generally the spectra are reproducible shot to shot. We observed that the laser-produced microplasma did not initiate any of the energetic materials studied. Extensive studies of black powder and its ingredients by use of a reference spectral library have demonstrated excellent accuracy for unknown identification. Finally, we observed that these nitrogen- and oxygen-rich materials yield LIBS spectra in air that have correspondingly different O:N peak ratios compared with air. This difference can help in the detection and identification of such energetic materials.

  4. Diagnostics for the detection and evaluation of laser induced damage

    International Nuclear Information System (INIS)

    The Laser Damage and Conditioning Group at LLNL is evaluating diagnostics which will help make damage testing more efficient and reduce the risk of damage during laser conditioning. The work to date has focused on photoacoustic and scattered light measurements on 1064-nm wavelength HfO2/SiO2 multilayer mirror and polarizer coatings. Both the acoustic and scatter diagnostics have resolved 10 μm diameter damage points in these coatings. Using a scanning stage, the scatter diagnostic can map both intrinsic and laser-induced scatter. Damage threshold measurements obtained using scatter diagnostics compare within experimental error with those measured using 100x Nomarski microscopy. Scatter signals measured during laser conditioning can be used to detect damage related to nodular defects

  5. Biological effects of laser-induced stress waves

    International Nuclear Information System (INIS)

    Laser-induced stress waves can be generated by one of the following mechanisms: Optical breakdown, ablation or rapid heating of an absorbing medium. These three modes of laser interaction with matter allow the investigation of cellular and tissue responses to stress waves with different characteristics and under different conditions. The most widely studied phenomena are those of the collateral damage seen in photodisruption in the eye and in 193 run ablation of cornea and skin. On the other hand, the therapeutic application of laser-induced stress waves has been limited to the disruption of noncellular material such as renal stones, atheromatous plaque and vitreous strands. The effects of stress waves to cells and tissues can be quite disparate. Stress waves can fracture tissue, damage cells, and increase the permeability of the plasma membrane. The viability of cell cultures exposed to stress waves increases with the peak stress and the number of pulses applied. The rise time of the stress wave also influences the degree of cell injury. In fact, cell viability, as measured by thymidine incorporation, correlates better with the stress gradient than peak stress. Recent studies have also established that stress waves induce a transient increase of the permeability of the plasma membrane in vitro. In addition, if the stress gradient is below the damage threshhold, the cells remain viable. Thus, stress waves can be useful as a means of drug delivery, increasing the intracellular drug concentration and allowing the use of drugs which are impermeable to the cell membrane. The present studies show that it is important to create controllable stress waves. The wavelength tunability and the micropulse structure of the free electron laser is ideal for generating stress waves with independently adjustable parameters, such as rise time, duration and peak stress

  6. Discriminating crude oil grades using laser-induced breakdown spectroscopy

    Science.gov (United States)

    El-Hussein, A.; Marzouk, A.; Harith, M. A.

    2015-11-01

    The analysis of crude oil using laser-based analytical techniques such as laser-induced breakdown spectroscopy (LIBS) has become of great interest to various specialists in different fields such as geology, petro-chemistry and environmental science. In this work, a detailed study is presented wherein the implementation of an efficient and simple LIBS technique to identify the elemental constituents of crude oil and to distinguish between different grades of petroleum crude oil is discussed. Laser-induced plasma (LIP) technique has been used in this work for direct measurements of atomic, ionic and molecular species in dry crude oil samples with API gravities ranging between 18 and 36. The technique was implemented using the first harmonic of a pulsed Nd-YAG laser source. Atomic and molecular emission bands were observed, consisting of characteristic spectral lines of atoms and diatomic molecular bands, namely from C, H, Si, Na, Ca, Mg, AL, Fe, Ti, Mo, C2 and CN. The intensities of high-resolution spectral lines for some atoms and molecules of elements such as Ca, Na, Fe, Mo, C2 and CN were evaluated at different wavelengths along the obtained spectra. The molecular bands and the elemental spectral lines were used to assess the possibility of adopting the LIBS technique in differentiating between crude oil samples with different American Petroleum Institute (API) gravity values. The results indicate the presence of a distinct correlation between the API gravity values of the various oil samples and the spectral line intensities of the elements and some molecular radical constituents. In addition, the possibility of identifying the API gravity values of unknown oil samples is also indicated.

  7. Titanium monoxide spectroscopy following laser-induced optical breakdown

    International Nuclear Information System (INIS)

    This work investigates Titanium Monoxide (TiO) in ablation-plasma by employing laser-induced breakdown spectroscopy (LIBS) with 1 to 10 TW/cm2 irradiance, pulsed, 13 nanosecond, Q-switched Nd:YAG laser radiation at the fundamental wavelength of 1064 nm. The analysis of TiO is based on our first accurate determination of transition line strengths for selected TiO A-X, B-X, and E-X transitions, particularly TiO A-X γ and B-X γ′ bands. Electric dipole line strengths for the A3Φ-X3δ and B3Π-X3δ bands of TiO are computed. The molecular TiO spectra are observed subsequent to laser-induced breakdown (LIB). We discuss analysis of diatomic molecular spectra that may occur simultaneously with spectra originating from atomic species. Gated detection is applied to investigate the development in time of the emission spectra following LIB. Collected emission spectra allow one to infer micro-plasma parameters such as temperature and electron density. Insight into the state of the micro-plasma is gained by comparing measurements with predictions of atomic and molecular spectra. Nonlinear fitting of recorded and computed diatomic spectra provides the basis for molecular diagnostics, while atomic species may overlap and are simultaneously identified. Molecular diagnostic approaches similar to TiO have been performed for diatomic molecules such as AlO, C2, CN, CH, N2, NH, NO and OH.

  8. Choroidal Metastasis of Papillary Thyroid Carcinoma Demonstrated on SPECT-CT.

    Science.gov (United States)

    Torun, Nese; Reyhan, Mehmet; Yapar, Ali Fuat; Karatas, Muge

    2016-05-01

    We report a 68-year-old woman with papillary thyroid carcinoma metastasizing to choroid. The choroid metastasis was diagnosed with SPECT-CT and then was treated with high-dose radioactive iodine therapy. PMID:26825205

  9. Correlation between clinical and histological features in a pig model of choroidal neovascularization

    DEFF Research Database (Denmark)

    Lassota, Nathan; Kiilgaard, Jens Folke; Prause, Jan Ulrik; la Cour, Morten

    2006-01-01

    To analyse the histological changes in the retina and the choroid in a pig model of choroidal neovascularization (CNV) and to correlate these findings with fundus photographic and fluorescein angiographic features....

  10. Choroidal thickness following extrafoveal photodynamic treatment with verteporfin in patients with central serous chorioretinopathy

    DEFF Research Database (Denmark)

    Pryds, Anders; Larsen, Michael

    2012-01-01

    Purpose: To evaluate the effect of verteporfin photodynamic treatment (PDT) on choroidal thickness in patients with central serous chorioretinopathy (CSC). Methods: Choroidal thickness was measured with enhanced depth imaging- optical coherence tomography (EDI-OCT) before and after verteporfin PDT...

  11. Choroidal metastasis from early rectal cancer: Case report and literature review

    Directory of Open Access Journals (Sweden)

    Mitsuyoshi Tei

    2014-01-01

    CONCLUSION: This is the first report of choroidal metastasis from early rectal cancer. We consider it important to enforce systemic chemotherapy in addition to radiotherapy for choroidal metastasis from colorectal cancer.

  12. Liquid steel analysis by laser-induced plasma spectroscopy

    International Nuclear Information System (INIS)

    When a nanosecond pulsed laser is focused onto a sample and the intensity exceeds a certain threshold, material is vaporized and a plasma is formed above the sample surface. The laser-light becomes increasingly absorbed by inverse bremsstrahlung and by photo-excitation and photo-ionization of atoms and molecules. The positive feedback, by which the number of energetic electrons for ionization is increased in an avalanche-like manner under the influence of laser-light, is the so-called optical breakdown. Radiating excited atoms and ions within the expanding plasma plume produce a characteristic optical emission spectrum. A spectroscopic analysis of this optical emission of the laser-induced plasma permits a qualitative and quantitative chemical analysis of the investigated sample. This technique is therefore often called laser-induced plasma spectroscopy (LIPS) or laser-induced breakdown spectroscopy (LIBS). LIPS is a fast non-contact technique, by which solid, liquid or gaseous samples can be analyzed with respect to their chemical composition. Hence, it is an appropriate tool for the rapid in-situ analysis of not easily accessible surfaces for process control in industrial environments. In this work, LIPS was studied as a technique to determine the chemical composition of solid and liquid steel. A LIPS set-up was designed and built for the remote and continuous in-situ analysis of the steel melt. Calibration curves were prepared for the LIPS analysis of Cr, Mn, Ni and Cu in solid steel using reference samples with known composition. In laboratory experiments an induction furnace was used to melt steel samples in crucibles, which were placed at a working distance of 1.5 m away from the LIPS apparatus. The response of the LIPS system was monitored on-line during the addition of pure elements to the liquid steel bath within certain concentration ranges (Cr: 0.11 - 13.8 wt%, Cu: 0.044 - 0.54 wt%, Mn: 1.38 - 2.5 wt%, Ni: 0.049 - 5.92 wt%). The analysis of an element

  13. Our Treatment Results of Circumscribed and Diffuse Choroidal Hemangiomas

    Directory of Open Access Journals (Sweden)

    Esra Savku

    2013-08-01

    Full Text Available Purpose: To discuss our treatment results of choroidal hemangiomas. Material and Method: The records of 39 cases of choroidal hemangioma followed up at our clinic between July 1999–October 2012 were reviewed retrospectively. Asymptomatic cases were followed up. Symptomatic cases with subretinal fluid and impaired vision received treatment. Results: Mean age of the 39 patients was 44 (12-80 years. Thirty-five of 39 cases had circumscribed choroidal hemangioma, and 4 cases had diffuse choroidal hemangioma. Sturge-Weber syndrome was present in 3 cases with diffuse choroidal hemangioma. Cases with circumscribed choroidal hemangioma and minimal subretinal fluid were treated with TTT in 11 cases, PDT in 12 cases, and PDT+TTT in 1 case. Cases with circumscribed choroidal hemangioma and excessive subretinal fluid were treated with Ru-106 plaque radiotherapy in 1 case, Ru-106 plaque radiotherapy+TTT in 1 case, EBRT in 3 cases, and TTT+EBRT in 1 case. One painful blind eye with neovascular glaucoma and complicated cataract was enucleated. Cases with diffuse choroidal hemangioma and excessive subretinal fluid were treated with Ru-106 plaque radiotherapy+TTT in 1 case and EBRT in 1 case. Ahmed glaucoma valve implantation and FAKO emulsification were applied to a case with neovascular glaucoma and complicated cataract. Complete resorption of subretinal fluid was achieved in 23 (72% of treated 32 cases. When mean initial tumor thickness was 2.6 mm (0.5-6, mean final tumor thickness was 1.4 mm (0-6. When mean initial visual acuity (LogMAR was 1.5 (0-3, mean final visual acuity was 1.1 (0-3. No recurrence was observed. Discussion: The amount of the subretinal fluid determines the method of treatment in circumscribed choroidal hemangioma. While TTT and PDT are effective treatment modalities for minimal subretinal fluid, plaque radiotherapy and EBRT are applied in cases with excessive subretinal fluid. Combination therapies may be necessary according to the

  14. Gamma Knife Radiosurgery for Choroidal Hemangioma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yun Taek; Kang, Se Woong [Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Lee, Jung-Il, E-mail: jilee@skku.edu [Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2011-12-01

    Purpose: Patients with choroidal hemangioma (CH), a benign ocular hamartoma, frequently presents with visual disturbance as a result of exudative retinal detachment (RD), which originates in subretinal fluid accumulation. We report our experience using the Leksell Gamma Knife in the management of symptomatic CH. Methods and Materials: Seven patients with symptomatic CH (circumscribed form in 3 patients and diffuse form in 4) were treated with the Leksell Gamma Knife at our institution during a 7-year period. All patients presented with exudative RD involving the macula that resulted in severe visual deterioration. The prescription dose to the target margin was 10 Gy in all cases. The mean tumor volume receiving the prescription dose was 536 mm{sup 3} (range, 151-1,057). The clinical data were analyzed in a retrospective fashion after a mean follow-up of 34.4 months (range, 9-76). Results: The resolution of exudative RD was achieved within 6 months, and the visual acuity of the affected eye had improved at the latest follow-up examination (p = .018) in all patients. No recurrence of exudative RD occurred. Thinning of the CHs was observed in most patients; however, symptomatic radiation toxicity had not developed in any of the patients. Conclusion: Symptomatic CHs can be safely and effectively managed with Gamma Knife radiosurgery using a marginal dose of 10 Gy.

  15. Is asthma related to choroidal neovascularization?

    Directory of Open Access Journals (Sweden)

    Yaoyao Sun

    Full Text Available BACKGROUND: Age-related degeneration (AMD and asthma are both diseases that are related to the activation of the complement system. The association between AMD and asthma has been debated in previous studies. The authors investigated the relationship between AMD and asthma systemically. PRINCIPAL FINDINGS: The epidemiological study showed that asthma was related to choroidal neovascularization (CNV subtype (OR = 1.721, P = 0.023. However, the meta-analysis showed there was no association between AMD and asthma. In an animal model, we found more fluoresce in leakage of CNV lesions by FA analysis and more angiogenesis by histological analysis in rats with asthma. Western blot demonstrated an elevated level of C3α-chain, C3α'-chain and VEGF. After compstatin was intravitreally injected, CNV leakage decreased according to FA analysis, with the level of C3 and VEGF protein decreasing at the same time. SIGNIFICANCE: This study first investigated the relationship between AMD and asthma systematically, and it was found that asthma could be a risk factor for the development of AMD. The study may provide a better understanding of the disease, which may advance the potential for screening asthma patients in clinical practice.

  16. Charged particle radiotherapy for choroidal melanoma

    International Nuclear Information System (INIS)

    The phase I/II clinical study of carbon ion radiotherapy (CIRT) for choroidal melanoma was commenced in Jan. 2001 at the National Institute of Radiological Sciences (NIRS), which was based on the long line of the study of proton radiotherapy (PRT) since Oct. 1986. PRT is applied to small to medium sized tumor, and carbon is used to large sized tumor at present. So far 41 patients received PRT. Skin reactions and visual acuity status after the therapy were acceptable. Seven patients developed glaucoma and one of them received enucleation. Local recurrence was observed in one patient and 5-year local control rate was 97.4%. Five-year survival and eye retention rate were 85.4% and 95%, respectively. On the other hand, thirty-three patients received CIRT and 24 patients with follow-up period of more than 6 months were analyzed. Skin reactions after CIRT were comparable to those of PRT. Neovascular glaucoma was observed in 7 patients and the incidence of glaucoma was strongly depending on the site and size of the tumor. All patients were alive without any local recurrence, and only one patient developed liver metastasis at 22.3 months after the treatment. (author)

  17. Laser induced damage of fused silica polished optics due to a droplet forming organic contaminant

    Energy Technology Data Exchange (ETDEWEB)

    Bien-Aime, Karell; Neauport, Jerome; Tovena-Pecault, Isabelle; Fargin, Evelyne; Labrugere, Christine; Belin, Colette; Couzi, Michel

    2009-04-20

    We report on the effect of organic molecular contamination on single shot laser induced damage density at the wavelength of 351 nm, with a 3 ns pulse length. Specific contamination experiments were made with dioctylphthalate (DOP) in liquid or gaseous phase, on the surface of fused silica polished samples, bare or solgel coated. Systematic laser induced damage was observed only in the case of liquid phase contamination. Different chemical and morphological characterization methods were used to identify and understand the damage process. We demonstrate that the contaminant morphology, rather than its physicochemical nature, can be responsible for the decrease of laser induced damage threshold of optics.

  18. Laser induced damage of fused silica polished optics due to a droplet forming organic contaminant.

    Science.gov (United States)

    Bien-Aimé, Karell; Néauport, Jérome; Tovena-Pecault, Isabelle; Fargin, Evelyne; Labrugère, Christine; Belin, Colette; Couzi, Michel

    2009-04-20

    We report on the effect of organic molecular contamination on single shot laser induced damage density at the wavelength of 351 nm, with a 3 ns pulse length. Specific contamination experiments were made with dioctylphthalate (DOP) in liquid or gaseous phase, on the surface of fused silica polished samples, bare or solgel coated. Systematic laser induced damage was observed only in the case of liquid phase contamination. Different chemical and morphological characterization methods were used to identify and understand the damage process. We demonstrate that the contaminant morphology, rather than its physicochemical nature, can be responsible for the decrease of laser induced damage threshold of optics. PMID:19381171

  19. Multivariate Analysis of Laser-Induced Breakdown Spectroscopy for Discrimination between Explosives and Plastics

    International Nuclear Information System (INIS)

    A method to distinguish explosives from plastics using laser-induced breakdown spectroscopy is discussed. A model for classification with cross-validation theory is built based on the partial least-square discriminant analysis method. Seven types of plastics and one explosive are used as samples to test the model. The experimental results demonstrate that laser-induced breakdown spectroscopy has the capacity to discriminate explosives from plastics combined with chemometrics methods. The results could be useful for prospective research of laser-induced breakdown spectroscopy on the differentiation of explosives and other materials. (fundamental areas of phenomenology(including applications))

  20. Theoretical analysis for temperature dependence of laser- induced damage threshold of optical thin films

    Science.gov (United States)

    Mikami, K.; Motokoshi, S.; Somekawa, T.; Jitsuno, T.; Fujita, M.; Tanaka, KA; Azechi, H.

    2016-03-01

    The temperature dependence of the laser-induced damage threshold on optical coatings was studied in detail for laser pulses from 123 K to 473 K at different temperatures. The laser-induced damage threshold increased with decreasing temperatures when we tested long pulses (200 ps and 4 ns). The temperature dependence, however, was reversed for pulses shorter than a few picoseconds (100 fs testing). We propose a scaling model with a flowchart that includes three separate processes: free-electron generation, electron multiplication, and electron heating. Furthermore, we calculated the temperature dependence of laser-induced damage thresholds at different temperatures. Our calculation results agreed well with the experimental results.

  1. Nanosecond laser-induced synthesis of nanoparticles with tailorable magneticanisotropy

    International Nuclear Information System (INIS)

    Controlling the magnetic orientation of nanoparticles is important for many applications. Recently, it has been shown that single domain ferromagnetic hemispherical Co nanoparticles prepared by nanosecond laser-induced self-organization, show magnetic orientation that was related to the negative sign of the magnetostrictive coefficient λS [J. Appl. Phys. v103, p073902, 2008]. Here we have extended this work to the Fe50Co50 alloy, which has a positive λS and Ni, which has a negative λS. Patterned arrays of ferromagnetic nanoparticles of Fe50Co50, Ni, (and Co) were synthesized from their ultrathin metal films on SiO2 substrate by nanosecond laser-induced self-organization. The morphology, nanostructure, and magnetic behavior of the nanoparticle arrays were investigated by a combination of electron microscopy, atomic force microscopy, and magnetic force microscopy techniques. Transmission electron microscopy investigations revealed a granular polycrystalline nanostructure, with the number of grains inside the nanoparticle increasing with their diameter. Magnetic force measurements showed that the magnetization direction of the hemispherical Co and Ni nanoparticles was predominantly out-of-plane while those for the Fe50Co50 alloy was in the plane of the substrate. Finite element analysis was used to estimate the average residual strain in the nanoparticles, following laser processing. The difference in behavior is due to the dominating influence of magnetostrictive energy on the magnetization as a result of residual thermal strain following fast laser processing. Since λS is negative for polycrystalline Co and Ni, and positive for Fe50Co50, the tensile residual strain forces the magnetization direction to out-of-plane and in-plane, respectively. This work demonstrates a cost-effective non-epitaxial technique for the synthesis of magnetic nanoparticles with tailored magnetization orientations. - Research Highlights: → Pulsed laser self-organization of

  2. Elemental analysis of cotton by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schenk, Emily R.; Almirall, Jose R.

    2010-05-01

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the elemental characterization of unprocessed cotton. This research is important in forensic and fraud detection applications to establish an elemental fingerprint of U.S. cotton by region, which can be used to determine the source of the cotton. To the best of our knowledge, this is the first report of a LIBS method for the elemental analysis of cotton. The experimental setup consists of a Nd:YAG laser that operates at the fundamental wavelength as the LIBS excitation source and an echelle spectrometer equipped with an intensified CCD camera. The relative concentrations of elements Al, Ba, Ca, Cr, Cu, Fe, Mg, and Sr from both nutrients and environmental contributions were determined by LIBS. Principal component analysis was used to visualize the differences between cotton samples based on the elemental composition by region in the U.S. Linear discriminant analysis of the LIBS data resulted in the correct classification of >97% of the cotton samples by U.S. region and >81% correct classification by state of origin.

  3. Hyperspectral laser-induced autofluorescence imaging of dental caries

    Science.gov (United States)

    Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

    2012-01-01

    Dental caries is a disease characterized by demineralization of enamel crystals leading to the penetration of bacteria into the dentine and pulp. Early detection of enamel demineralization resulting in increased enamel porosity, commonly known as white spots, is a difficult diagnostic task. Laser induced autofluorescence was shown to be a useful method for early detection of demineralization. The existing studies involved either a single point spectroscopic measurements or imaging at a single spectral band. In the case of spectroscopic measurements, very little or no spatial information is acquired and the measured autofluorescence signal strongly depends on the position and orientation of the probe. On the other hand, single-band spectral imaging can be substantially affected by local spectral artefacts. Such effects can significantly interfere with automated methods for detection of early caries lesions. In contrast, hyperspectral imaging effectively combines the spatial information of imaging methods with the spectral information of spectroscopic methods providing excellent basis for development of robust and reliable algorithms for automated classification and analysis of hard dental tissues. In this paper, we employ 405 nm laser excitation of natural caries lesions. The fluorescence signal is acquired by a state-of-the-art hyperspectral imaging system consisting of a high-resolution acousto-optic tunable filter (AOTF) and a highly sensitive Scientific CMOS camera in the spectral range from 550 nm to 800 nm. The results are compared to the contrast obtained by near-infrared hyperspectral imaging technique employed in the existing studies on early detection of dental caries.

  4. Characteristics of Ions Emitted from Laser-Induced Silver Plasma

    Institute of Scientific and Technical Information of China (English)

    M. S. RAFIQUE; M. KHALEEQ-UR-RAHMAN; Shakoor MUNAZZA; K. A. BHATTI

    2008-01-01

    In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd:YAG laser, with a wavelength of 1064 nm, a pulsed width of 9~14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum (10'-3> Torr = 1.3332 Pa). The charac-teristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour.

  5. Drift mechanism of laser-induced electron acceleration in vacuum

    Science.gov (United States)

    Morgovsky, L.

    2015-12-01

    Laser-induced electron acceleration in vacuum is possible due to the ejection of electrons from the beam as a consequence of the transverse drift orthogonal to the propagation direction. The transverse drift is derived from the general solution of the equations of motion of the electrons in the field of a plane electromagnetic wave with arbitrary polarization. It is shown that the energy gain is proportional to the square of the field strength additionally modulated by the function of the injection and ejection phases. In particular, for a linearly polarized beam this function is reduced to the squared difference between the cosines of these phases. The finite laser pulse duration restricts the range of the field strength suitable for direct electron acceleration in vacuum within certain limits. It is demonstrated that the high efficiency of energy transfer from the laser wave into the kinetic energy of the accelerated electrons demands phase matching between the electron quiver phase at the exit point and the phase of the energy transfer.

  6. Theoretical considerations of laser induced liquid-liquid interface deformation

    CERN Document Server

    Aanensen, Nina Sasaki; Brevik, Iver

    2013-01-01

    In the increasingly active field of optofluidics, a series of experiments involving near-critical two-fluid interfaces have shown a number of interesting non-linear effects. We here offer, for the first time to our knowledge, an explanation for one such feature, observed in experiments by Casner and Delville [Phys. Rev. Lett. {\\bf 90}, 144503 (2003)], namely the sudden formation of "shoulder"-like shapes in a laser-induced deformation of the liquid-liquid interface at high laser power. Two candidate explanations are the following: firstly, that the shape can be explained by balancing forces of buoyancy, laser pull and surface tension only, and that the observed change of deformation shape is the sudden jump from one solution of the strongly nonlinear governing differential equation to another. Secondly, it might be that the nontrivial shape observed could be the result of temperature gradients due to local absorptive heating of the liquid. We report that a systematic search for solutions of the governing equa...

  7. Laser-induced breakdown spectroscopy expands into industrial applications

    International Nuclear Information System (INIS)

    This paper presents R and D activities in the field of laser-induced breakdown spectroscopy for industrial applications and shows novel LIBS systems running in routine operation for inline process control tasks. Starting with a comparison of the typical characteristics of LIBS with XRF and spark-discharge optical emission spectrometry, the principal structure of LIBS machines embedded for inline process monitoring will be presented. A systematic requirement analysis for LIBS systems following Ishikawa's scheme was worked out. Stability issues are studied for laser sources and Paschen-Runge spectrometers as key components for industrial LIBS systems. Examples of industrial applications range from handheld LIBS systems using a fiber laser source, via a set of LIBS machines for inline process control tasks, such as scrap analysis, coal analysis, liquid slag analysis and finally monitoring of drill dust. - Highlights: • New applications for LIBS realized within the last five years • Systematic requirement analysis for industrial LIBS systems • First long-term studies of key components • Demonstration of LIBS potential for inline chemical analysis

  8. Laser-Induced Incandescence Measurements in Low Gravity

    Science.gov (United States)

    VanderWal, R. L.

    1997-01-01

    A low-gravity environment offers advantages to investigations concerned with soot growth or flame radiation by eliminating of buoyancy-induced convection. Basic to each type of study is knowledge of spatially resolved soot volume fraction, (f(sub v). Laser-induced incandescence (LII) has emerged as a diagnostic for soot volume fraction determination because it possesses high temporal and spatial resolution, geometric versatility and high sensitivity. Implementation and system characterization of LII in a drop tower that provides 2.2 sec of low-gravity (micro)g) at the NASA Lewis Research Center are described here. Validation of LII for soot volume fraction determination in (micro)g is performed by comparison between soot volume fraction measurements obtained by light extinction [20] and LII in low-gravity for a 50/50 mixture (by volume) of 0 acetylene/nitrogen issuing into quiescent air. Quantitative soot volume fraction measurements within other laminar flames of ethane and propane and a turbulent diffusion flame in (micro)g via LII are also demonstrated. An analysis of LII images of a turbulent acetylene diffusion flame in 1-g and (micro)g is presented.

  9. Independent component analysis classification of laser induced breakdown spectroscopy spectra

    Science.gov (United States)

    Forni, Olivier; Maurice, Sylvestre; Gasnault, Olivier; Wiens, Roger C.; Cousin, Agnès; Clegg, Samuel M.; Sirven, Jean-Baptiste; Lasue, Jérémie

    2013-08-01

    The ChemCam instrument on board Mars Science Laboratory (MSL) rover uses the laser-induced breakdown spectroscopy (LIBS) technique to remotely analyze Martian rocks. It retrieves spectra up to a distance of seven meters to quantify and to quantitatively analyze the sampled rocks. Like any field application, on-site measurements by LIBS are altered by diverse matrix effects which induce signal variations that are specific to the nature of the sample. Qualitative aspects remain to be studied, particularly LIBS sample identification to determine which samples are of interest for further analysis by ChemCam and other rover instruments. This can be performed with the help of different chemometric methods that model the spectra variance in order to identify a the rock from its spectrum. In this paper we test independent components analysis (ICA) rock classification by remote LIBS. We show that using measures of distance in ICA space, namely the Manhattan and the Mahalanobis distance, we can efficiently classify spectra of an unknown rock. The Mahalanobis distance gives overall better performances and is easier to manage than the Manhattan distance for which the determination of the cut-off distance is not easy. However these two techniques are complementary and their analytical performances will improve with time during MSL operations as the quantity of available Martian spectra will grow. The analysis accuracy and performances will benefit from a combination of the two approaches.

  10. Laser-induced autofluorescence study of caries model in vitro.

    Science.gov (United States)

    Borisova, Ekaterina; Uzunov, Tzonko; Avramov, Latchezar

    2006-04-01

    Laser-induced autofluorescence spectra of teeth irradiated by a 337 nm nitrogen laser were measured during in vitro caries formation through initial enamel demineralization and introducing of carious bacterial flora in the lesions developed. Spectra obtained from sound teeth consist of an intensive maximum at 480-500 nm and secondary maximum at 430-450 nm. In the process of caries formation, we observed an increase in the intensity at 430-450 nm and the appearance of two maxima in the red spectral region-at 590-650 nm. The intensity increase at 430-450 nm was related to the tooth demineralization. Bacteria presence and their metabolism products induced an increase in the absorption in the UV-blue spectral region at 350-420 nm and the appearance of a fluorescence signal in the long-wave spectral region at 590-650 nm. From the point of view of tissue optics, these results allow caries to be considered as consisting of two different phenomena-tissue destruction and bacterial flora and its metabolism products increase. The results could be used to obtain a more complete picture of caries formation on the base of its fluorescent properties. PMID:16568211

  11. Measuring turbulent fluid dispersion using laser induced phosphorescence

    Science.gov (United States)

    van der Voort, Dennis; Dam, Nico; van de Water, Willem; Kunnen, Rudie; Clercx, Herman; van Heijst, Gertjan

    2015-11-01

    Fluid dispersion due to turbulence is an important subject in both natural and engineering processes, from cloud formation to turbulent mixing and liquid spray combustion. The combination of small scales and often high velocities results in few experimental techniques that can follow the course of events. We introduce a novel technique, which measures the dispersion of ``tagged'' fluid particles by means of laser-induced phosphorescence, using a solution containing a europium-based molecular complex with a relatively long phosphorescence half-life. This technique is used to measure transport processes in both the dispersion of droplets in homogeneous isotropic turbulence and the dispersion of fluid of near-nozzle spray breakup processes. By tagging a small amount of droplets/fluid via laser excitation, the tagged droplets can be tracked in a Lagrangian way. The absolute dispersion of the droplets can be measured in a variety of turbulent flows. Using this technique it is shows that droplets around St =τp /τη ~ 1 (Stokes number) disperse faster than true fluid tracers in homogeneous isotropic turbulence, as well as differences between longitudinal and radial dispersion in turbulent sprays. This work is part of the research programme of the Foundation for Fundamental Research on Matter (FOM), which is part of the Dutch Organisation for Scientific Research (NWO).

  12. Slag analysis with laser-induced breakdown spectrometry.

    Science.gov (United States)

    Kraushaar, M; Noll, R; Schmitz, H U

    2003-10-01

    Laser-induced breakdown spectrometry (LIBS) has been applied for multi-elemental analysis of slag samples from a steel plant. In order to avoid the time-consuming step of sample preparation, the liquid slag material can be filled in special probes. After cooling of the liquid slag and solidification, the samples can be analyzed with LIBS. Chemical analysis of slag is an essential input parameter used for numerical simulations to control liquid steel processing. The relative variation range of element concentrations in slag samples from steel production can amount to up to 30%. A multivariate calibration model is used to take into account matrix effects caused by these varying concentrations. By optimizing the measuring parameters as well as the calibration models, an agreement between the standard X-ray fluorescence (XRF) analysis and LIBS analysis in terms of the coefficient of determination r2 of 0.99 for the main analytes CaO, SiO2, and Fetot of converter slag samples was achieved. The average repeatability of the LIBS measurement for these elements in terms of the relative standard deviation of the determined concentration is improved to less than 1.0%. With these results, the basis is established for future on-line applications of LIBS in the steel-making industry for slag analysis. PMID:14639759

  13. Elemental analysis of cotton by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the elemental characterization of unprocessed cotton. This research is important in forensic and fraud detection applications to establish an elemental fingerprint of U.S. cotton by region, which can be used to determine the source of the cotton. To the best of our knowledge, this is the first report of a LIBS method for the elemental analysis of cotton. The experimental setup consists of a Nd:YAG laser that operates at the fundamental wavelength as the LIBS excitation source and an echelle spectrometer equipped with an intensified CCD camera. The relative concentrations of elements Al, Ba, Ca, Cr, Cu, Fe, Mg, and Sr from both nutrients and environmental contributions were determined by LIBS. Principal component analysis was used to visualize the differences between cotton samples based on the elemental composition by region in the U.S. Linear discriminant analysis of the LIBS data resulted in the correct classification of >97% of the cotton samples by U.S. region and >81% correct classification by state of origin.

  14. Laser-induced surface modification and metallization of polymers

    Science.gov (United States)

    Frerichs, Hartmut; Wesner, David A.; Kreutz, Ernst-Wolfgang

    1995-04-01

    Laser-induced surface modification of various polymers is presented as a suitable pretreatment of surfaces in a two-step metallization process. Materials such as polyamide (PA), polypropylene (PP), polystyrene (PS), polycarbonate (PC), acrylbutadienestyrene (ABS), styreneacrylnitril (SAN), polybutadieneterphtalate (PBT), and polyoxymethylen (POM) were treated by excimer laser radiation ((lambda) equals 248 nm) in air. The aim of this study is to investigate different processing regimes of surface modification. Therefore the laser processing variables fluence F, repetition rate v and pulse number N are varied and the absorption coefficient, optical penetration depth, ablation depth and ablation threshold are determined. The surface morphology and surface roughness are studied by optical surface profilometry and secondary electron microscopy (SEM). The influence of laser treatment on chemical composition of modified and ablated surfaces is analyzed by X-ray photoelectron spectroscopy (XPS). Depending on the processing parameters and materials properties different microstructures and values of surface roughness are generated on the micrometer length scale. Pretreatment for the subsequent metallization is performed with laser radiation, wet chemical and plasma etching. The metallization of polymers is investigated for different surface morphologies. The used metallization processes are electroplating and physical vapor deposition (PVD). Adhesion of the deposited films, measured with scratch and tape test methods, is used as a criterion for determining regimes of suitable surface modification for subsequent metallization.

  15. Hydrogen Balmer Series Measurements in Laser-Induced Air Plasma

    International Nuclear Information System (INIS)

    Time-resolved spectroscopy is employed to analyze micro plasma generated in laboratory air. Stark-broadened emission profiles for hydrogen alpha and beta allow us to determine plasma characteristics for specific time delays after plasma generation. Stark shift, asymmetry, and full width half maximum measurements are used to infer electron density. The measurements of hydrogen alpha and beta Balmer series line shapes are analyzed using various theory results. Our laser-induced breakdown spectroscopy arrangement uses a Q- switched Nd:YAG laser operating at the fundamental wavelength of 1064 nm that is focused for plasma generation. The hydrogen alpha and beta lines emerge from the free electron background radiation for time delays larger than 0.3 ps and 1.4 ps, respectively. Neutral and ionized nitrogen emission lines allow us to infer electron density for time delays from 0.1 to 10 μs. The electron density values are compared with results obtained from hydrogen Balmer series line shapes

  16. Refining femtosecond laser induced periodical surface structures with liquid assist

    International Nuclear Information System (INIS)

    Highlights: ► LIPSS on silicon wafer was made in air and in ethanol environment. ► Ethanol environment produce cleaner surface ripples. ► Ethanol environment decrease spatial wavelength of the LIPSS by 30%. ► More number of pulses produce smaller spatial wavelength in air. ► Number of pulses do not influence spatial wavelength in ethanol environment. - Abstract: Laser induced periodic surface structures were generated on silicon wafer using femtosecond laser. The medium used in this study is both air and ethanol. The laser process parameters such as wavelength, number of pulse, laser fluence were kept constant for both the mediums. The focus of the study is to analyze spatial wavelength. When generating surface structures with air as a medium and same process parameter of the laser, spatial wavelength results showed a 30% increase compared to ethanol. The cleanliness of the surface generated using ethanol showed considerably less debris than in air. The results observed from the above investigation showed that the medium plays a predominant role in the generation of surface structures.

  17. Laser-induced forward transfer (LIFT) of congruent voxels

    Science.gov (United States)

    Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C. Y.; Beniam, Iyoel; Breckenfeld, Eric

    2016-06-01

    Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D and 3D microstructures by adjusting the viscosity of the nano-suspension and laser transfer parameters.

  18. Production of biomolecule microarrays through laser induced forward transfer

    Science.gov (United States)

    Fernandez-Pradas, Juan Marcos; Serra, Pere; Colina, Monica; Morenza, Jose-Luis

    2004-10-01

    Biomolecule microarrays are a kind of biosensors that consist in patterns of different biological molecules immobilized on a solid substrate and capable to bind specifically to their complementary targets. In particular, DNA and protein microarrays have been revealed to be very efficient devices for genen and protein identification, what has converted them in powerful tools for many applications, like clinical diagnose, drug discovery analysis, genomics and proteomics. The production of these devices requires the manipulation of tiny amounts of a liquid solution containing biomolecules without damaging them. In this work laser induced forward transfer (LIFT) has been used for spotting a biomolecule in order to check the viability of this technique for the production of microarrays. A pulsed Nd:YAG laser beam (355 nm wavelength) has been used to transfer droplets of a biomolecule containing solution onto a solid slide. Optical microscopy of the transferred material has been carried out to investigate the morphological characteristics of the droplets obtained under different irradiation conditions. Afterwards, a DNA microarray has been spotted. The viability of the transference has been tested by checking the biological activity of the biomolecule in front of its specific complementary target. This has revealed that, indeed, the LIFT technique is adequate for the production of DNA microarrays.

  19. Laser Induced Breakdown Spectroscopy, advances in resolution and portability

    International Nuclear Information System (INIS)

    Laser Induced Breakdown Spectroscopy (LIBS), can be considered as one of the most dynamic and promising technique in the field of analytical spectroscopy. LIBS has turned into a powerful alternative for a wide front of applications, from the geological exploration to the industrial inspection, including the environmental monitoring, the biomedical analysis, the study of patrimonial works, the safety and defense. The advances in LIBS instrumentation have allowed improving gradually the analysis services and quality, on the basis of a better knowledge of the technology principles. Recently, systems of double pulse have facilitated a better dosing of energy, the improvement of the signal-noise relation and the study of the different process stages. Femtosecond lasers offers the possibility of study in detail the ablation and atomic emission processes. New advances like multi-pulse or multi-wavelength systems -in fact stilling without exploring, must offer new information to advance in this knowledge. Finally, which it does to this technology really attractive, is the aptitude to be employed in field conditions, or for the detection of the elementary composition at long distances. In this presentation there are discussed the designs of portable instrumentation, compact and low cost, which can improve substantially the LIBS possibilities. (Author)

  20. Laser-induced Forward Transfer of Ag Nanopaste

    Science.gov (United States)

    Breckenfeld, Eric; Kim, Heungsoo; Auyeung, Raymond C. Y.; Piqué, Alberto

    2016-01-01

    Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of these processes such as inkjet3 and laser-induced forward transfer (LIFT)4 have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)5-9, has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip. PMID:27077645

  1. Doping of silicon by laser-induced diffusion

    International Nuclear Information System (INIS)

    This report gives information on the doping of silicon by laser-induced diffusion, modelling and heat-flow calculation, doping from evaporated layers and silicon self-diffusion during pulsed laser irradiation. In order to tailor dopant profiles accurately a knowledge of the heat flow and the melt depths attained as a function of laser energy and material type is crucial. The heat flow calculations described can be used in conjuntion with most diffusion equations in order to predict the redistribution of the deposited dopant which occurs as a result of liquid phase diffusion during the melting period. Doping of Si was carried out by evaporating this films of Sb, In and Bi 10 to 300 A thick, onto the substrates. During pulsed laser irradiation the dopant film and underlying silicon substrate is melted and the dopant incorporated into the crystal lattice during recrystallization. Radioactive 31Si(T1/2=2,62h) was used as a tracer to measure the self-diffusion of silicon in silicon during pulsed laser (pulsewidth = 30ns, wavelength = 694nm) irradiation

  2. The LILIA (laser induced light ions acceleration) experiment at LNF

    Energy Technology Data Exchange (ETDEWEB)

    Agosteo, S. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Anania, M.P. [INFN LNF Frascati, Frascati (Italy); Caresana, M. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Cirrone, G.A.P. [INFN LNS Catania, Catania (Italy); De Martinis, C. [Physics Department, University of Milan and INFN, Milan (Italy); Delle Side, D. [LEAS, University of Salento and INFN, Lecce (Italy); Fazzi, A. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Gatti, G. [INFN LNF Frascati, Frascati (Italy); Giove, D. [Physics Department, University of Milan and INFN, Milan (Italy); Giulietti, D. [Physics Department, University of Pisa and INFN, Pisa (Italy); Gizzi, L.A.; Labate, L. [INO-CNR and INFN, Pisa (Italy); Londrillo, P. [Physics Department, University of Bologna and INFN, Bologna (Italy); Maggiore, M. [INFN LNL, Legnaro (Italy); Nassisi, V., E-mail: vincenzo.nassisi@le.infn.it [LEAS, University of Salento and INFN, Lecce (Italy); Sinigardi, S. [Physics Department, University of Bologna and INFN, Bologna (Italy); Tramontana, A.; Schillaci, F. [INFN LNS Catania, Catania (Italy); Scuderi, V. [INFN LNS Catania, Catania (Italy); Institute of Physics of the ASCR, Prague (Czech Republic); Turchetti, G. [Physics Department, University of Bologna and INFN, Bologna (Italy); and others

    2014-07-15

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given.

  3. The LILIA (laser induced light ions acceleration) experiment at LNF

    International Nuclear Information System (INIS)

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given

  4. Lead determination in glasses by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Carmona, N. [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, Gregorio del Amo 8, 28040 Madrid (Spain)], E-mail: ncarmona@cenim.csic.es; Oujja, M.; Gaspard, S. [Instituto de Quimica Fisica Rocasolano, CSIC. Serrano 119, 28006 Madrid (Spain); Garcia-Heras, M. [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, Gregorio del Amo 8, 28040 Madrid (Spain); Instituto de Historia, CSIC. Serrano 13, 28001 Madrid (Spain); Villegas, M.A. [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, Gregorio del Amo 8, 28040 Madrid (Spain); Castillejo, M. [Instituto de Quimica Fisica Rocasolano, CSIC. Serrano 119, 28006 Madrid (Spain)], E-mail: marta.castillejo@iqfr.csic.es

    2007-02-15

    Laser-induced breakdown spectroscopy (LIBS) has been used to determine the lead content of different types of lead silicate glasses commercially designed as sonorous glass (which contain {approx} 10 wt.% PbO); crystal glass (with at least 24 wt.% PbO) and superior crystal glass (with at least 30 wt.% PbO). Seven different types of glass samples were selected, including historic-original, model and commercially available. The selected samples were artificially weathered under neutral, acid and alkaline attack. Analysis by LIBS was carried out in vacuum under excitation at 266 nm and results were compared with those obtained by conventional techniques used for glass characterization. Composition of the bulk glasses was analyzed by XRF (X-ray fluorescence) and the corroded surfaces were characterized by SEM/EDX (scanning electron microscopy/energy dispersive X-ray microanalysis). A linear correlation was obtained between the intensity of selected Pb lines in the LIB spectra and the PbO content. The effect of corrosion could be characterized by comparing successive LIB spectra recorded on the same area; acid attack resulted in a decrease of PbO, CaO and Na{sub 2}O content in the surface with respect to the bulk of the sample, while minor changes in the composition were noticed under alkaline attack. These results show LIBS as a useful technique to classify the different types of lead glasses by their lead content and to determine and asses the degree and type of corrosion.

  5. Estimating intercellular surface tension by laser-induced cell fusion

    International Nuclear Information System (INIS)

    Intercellular surface tension is a key variable in understanding cellular mechanics. However, conventional methods are not well suited for measuring the absolute magnitude of intercellular surface tension because these methods require determination of the effective viscosity of the whole cell, a quantity that is difficult to measure. In this study, we present a novel method for estimating the intercellular surface tension at single-cell resolution. This method exploits the cytoplasmic flow that accompanies laser-induced cell fusion when the pressure difference between cells is large. Because the cytoplasmic viscosity can be measured using well-established technology, this method can be used to estimate the absolute magnitudes of tension. We applied this method to two-cell-stage embryos of the nematode Caenorhabditis elegans and estimated the intercellular surface tension to be in the 30–90 µN m−1 range. Our estimate was in close agreement with cell–medium surface tensions measured at single-cell resolution. (communication)

  6. Femtosecond laser-induced periodic surface structures on silica

    Energy Technology Data Exchange (ETDEWEB)

    Hoehm, S.; Rosenfeld, A. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany); Krueger, J.; Bonse, J. [BAM Bundesanstalt fuer Materialforschung und-pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2012-07-01

    The formation of laser-induced periodic surface structures (LIPSS) on two different silica polymorphs (single-crystalline synthetic quartz and commercial fused silica glass) upon irradiation in air with multiple linearly polarized single- and double-fs-laser pulse sequences ({tau} = 150 fs pulse duration, {lambda} = 800 nm center wavelength, temporal pulse separation {Delta}t < 40 ps) is studied experimentally and theoretically. Two distinct types of fs-LIPSS [so-called low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL)] with different spatial periods and orientations were identified. Their appearance was characterized with respect to the experimental parameters peak laser fluence and number of laser pulses per spot. Additionally, the 'dynamics' of the LIPSS formation was addressed in complementary double-fs-pulse experiments with varying delays, revealing a characteristic change of the LSFL periods. The experimental results are interpreted on the basis of a Sipe-Drude model considering the carrier dependence of the optical properties of fs-laser excited silica. This new approach provides an explanation of the LSFL orientation parallel to the laser beam polarisation in silica - as opposed to the behaviour of most other materials.

  7. Airborne laser induced fluorescence imaging. Innovative technology summary report

    International Nuclear Information System (INIS)

    Laser-Induced Fluorescence (LIF) was demonstration as part of the Fernald Environmental Management Project (FEMP) Plant 1 Large Scale Demonstration and Deployment Project (LSDDP) sponsored by the US Department of Energy (DOE) Office of Science and Technology, Deactivation and Decommissioning Focus Area located at the Federal Energy Technology Center (FETC) in Morgantown, West Virginia. The demonstration took place on November 19, 1996. In order to allow the contaminated buildings undergoing deactivation and decommissioning (D and D) to be opened to the atmosphere, radiological surveys of floors, walls and ceilings must take place. After successful completion of the radiological clearance survey, demolition of the building can continue. Currently, this process is performed by collecting and analyzing swipe samples for radiological analysis. Two methods are used to analyze the swipe samples: hand-held frisker and laboratory analysis. For the purpose of this demonstration, the least expensive method, swipe samples analyzed by hand-held frisker, is the baseline technology. The objective of the technology demonstration was to determine if the baseline technology could be replaced using LIF

  8. Forensic comparative glass analysis by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Glass samples of four types commonly encountered in forensic examinations have been analyzed by laser-induced breakdown spectroscopy (LIBS) for the purpose of discriminating between samples originating from different sources. Some of the glass sets were also examined by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Refractive index (RI) measurements were also made on all glass samples and the refractive index data was combined with the LIBS and with the LA-ICP-MS data to enhance discrimination. The glass types examined included float glass taken from front and side automobile windows (examined on the non-float side), automobile headlamp glass, automobile side-mirror glass and brown beverage container glass. The largest overall discrimination was obtained by employing RI data in combination with LA-ICP-MS (98.8% discrimination of 666 pairwise comparisons at 95% confidence), while LIBS in combination with RI provided a somewhat lower discrimination (87.2% discrimination of 1122 pairwise comparisons at 95% confidence). Samples of side-mirror glass were less discriminated by LIBS due to a larger variance in emission intensities, while discrimination of side-mirror glass by LA-ICP-MS remained high

  9. Laser-induced breakdown plasma-based sensors

    Science.gov (United States)

    Griffin, Steven T.

    2010-04-01

    Laser Induced Breakdown Spectroscopy (LIBS) is dependent on the interaction between the initiating Laser sequence, the sampled material and the intermediate plasma states. Pulse shaping and timing have been empirically demonstrated to have significant impact on the signal available for active/passive detection and identification. The transient nature of empirical LIBS work makes data collection for optimization an expensive process. Guidance from effective computer simulation represents an alternative. This computational method for CBRNE sensing applications models the Laser, material and plasma interaction for the purpose of performance prediction and enhancement. This paper emphasizes the aspects of light, plasma, and material interaction relevant to portable sensor development for LIBS. The modeling structure emphasizes energy balances and empirical fit descriptions with limited detailed-balance and finite element approaches where required. Dusty plasma from partially decomposed material sample interaction with pulse dynamics is considered. This heuristic is used to reduce run times and computer loads. Computer simulations and some data for validation are presented. A new University of Memphis HPC/super-computer (~15 TFLOPS) is used to enhance simulation. Results coordinated with related effort at Arkansas State University. Implications for ongoing empirical work are presented with special attention paid to the application of compressive sensing for signal processing, feature extraction, and classification.

  10. Detection of vegetation stress from laser-induced fluorescence signatures

    International Nuclear Information System (INIS)

    The in vivo laser-induced fluorescence (LIF) signatures of UV irradiated Salvia splendens plants were measured using an Optical Multichannel Analyser (OMA) system with Nitrogen laser excitation. The LIF spectra which consisted of the blue-green and the red chlorophyll bands were analysed with a non-linear interactive procedure using Gaussian spectral functions. The fluorescence intensity ratios of the various bands obtained from curve fitted parameters were found to be more sensitive to changes in the photosynthetic activity of the plant. The variation in the intensity ratio for the chlorophyll bands for nutrient stressed sunflower, cotton and groundnut plants as well as the nutrient and water stressed rice plants are also presented. It is observed that vegetation stress not only changes the fluorescence intensity ratios and the vitality index of the plant but also changes the peak position of the emission bands, in some cases. It is also seen that analysis of the fluorescence spectra in vegetation remote sensing applications would require a deconvolution procedure to evaluate the exact contribution of each band in the total spectra. (author). 23 refs, 8 figs, 5 tabs

  11. Study of Bacterial Samples Using Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    W, A. Farooq; M, Atif; W, Tawfik; M, S. Alsalhi; Z, A. Alahmed; M, Sarfraz; J, P. Singh

    2014-12-01

    Laser-induced breakdown spectroscopy (LIBS) technique has been applied to investigate two different types of bacteria, Escherichia coli (B1) and Micrococcus luteus (B2) deposited on glass slides using Spectrolaser 7000. LIBS spectra were analyzed using spectrolaser software. LIBS spectrum of glass substrate was compared with bacteria spectra. Ca, Mg, Na, K, P, S, Cl, Fe, Al, Mn, Cu, C, H and CN-band appeared in bacterial samples in air. Two carbon lines at 193.02 nm, 247.88 nm and one hydrogen line at 656.28 nm with intensity ratios of 1.9, 1.83 and 1.53 appeared in bacterial samples B1 and B2 respectively. Carbon and hydrogen are the important components of the bio-samples like bacteria and other cancer cells. Investigation on LIBS spectra of the samples in He and Ar atmospheres is also presented. Ni lines appeared only in B2 sample in Ar atmosphere. From the present experimental results we are able to show that LIBS technique has a potential in the identification and discrimination of different types of bacteria.

  12. Laser-induced porous graphene films from commercial polymers

    Science.gov (United States)

    Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L. G.; Yacaman, Miguel Jose; Yakobson, Boris I.; Tour, James M.

    2014-12-01

    The cost effective synthesis and patterning of carbon nanomaterials is a challenge in electronic and energy storage devices. Here we report a one-step, scalable approach for producing and patterning porous graphene films with three-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp3-carbon atoms are photothermally converted to sp2-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF cm-2 and power densities of ~9 mW cm-2. Theoretical calculations partially suggest that enhanced capacitance may result from LIG’s unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices.

  13. The motional stark effect with laser-induced fluorescence diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Foley, E L; Levinton, F M, E-mail: foley@novaphotonics.co [Nova Photonics, Inc. 200 Forrestal Road Princeton NJ 08540 (United States)

    2010-05-01

    The motional Stark effect (MSE) diagnostic is the worldwide standard technique for internal magnetic field pitch angle measurements in magnetized plasmas. Traditionally, it is based on using polarimetry to measure the polarization direction of light emitted from a hydrogenic species in a neutral beam. As the beam passes through the magnetized plasma at a high velocity, in its rest frame it perceives a Lorentz electric field. This field causes the H-alpha emission to be split and polarized. A new technique under development adds laser-induced fluorescence (LIF) to a diagnostic neutral beam (DNB) for an MSE measurement that will enable radially resolved magnetic field magnitude as well as pitch angle measurements in even low-field (<1 T) experiments. An MSE-LIF system will be installed on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory. It will enable reconstructions of the plasma pressure, q-profile and current as well as, in conjunction with the existing MSE system, measurements of radial electric fields.

  14. Mid-infrared emission from laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Yang, Clayton S-C; Brown, Ei E; Hommerich, Uwe H; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

    2007-03-01

    Laser-induced breakdown spectroscopy (LIBS) is a powerful analytical technique for detecting and identifying trace elemental contaminants by monitoring the visible atomic emission from small plasmas. However, mid-infrared (MIR), generally referring to the wavelength range between 2.5 to 25 microm, molecular vibrational and rotational emissions generated by a sample during a LIBS event has not been reported. The LIBS investigations reported in the literature largely involve spectral analysis in the ultraviolet-visible-near-infrared (UV-VIS-NIR) region (less than 1 microm) to probe elemental composition and profiles. Measurements were made to probe the MIR emission from a LIBS event between 3 and 5.75 microm. Oxidation of the sputtered carbon atoms and/or carbon-containing fragments from the sample and atmospheric oxygen produced CO(2) and CO vibrational emission features from 4.2 to 4.8 microm. The LIBS MIR emission has the potential to augment the conventional UV-VIS electronic emission information with that in the MIR region. PMID:17389073

  15. Laser-induced Forward Transfer of Ag Nanopaste.

    Science.gov (United States)

    Breckenfeld, Eric; Kim, Heungsoo; Auyeung, Raymond C Y; Piqué, Alberto

    2016-01-01

    Over the past decade, there has been much development of non-lithographic methods(1-3) for printing metallic inks or other functional materials. Many of these processes such as inkjet(3) and laser-induced forward transfer (LIFT)(4) have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)(5-9), has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip. PMID:27077645

  16. Laser induced damage and fracture in fused silica vacuum windows

    International Nuclear Information System (INIS)

    Laser-induced damage, that initiates catastrophic fracture, has been observed in large (≤61 cm dia) fused silica lenses that also serve as vacuum barriers in Nova and Beamlet lasers. If the elastic stored energy in the lens is high enough, the lens will fracture into many pieces (implosion). Three parameters control the degree of fracture in the vacuum barrier window: elastic stored energy (tensile stress), ratio of window thickness to flaw depth, and secondary crack propagation. Fracture experiments were conducted on 15-cm dia fused silica windows that contain surface flaws caused by laser damage. Results, combined with window failure data on Beamlet and Nova, were used to develop design criteria for a ''fail-safe'' lens (that may catastrophically fracture but not implode). Specifically, the window must be made thick enough so that the peak tensile stress is less than 500 psi (3.4 MPa) and the thickness/critical flaw size is less than 6. The air leak through the window fracture and into the vacuum must be rapid enough to reduce the load on the window before secondary crack growth occurs. Finite element stress calculations of a window before and immediately following fracture into two pieces show that the elastic stored energy is redistributed if the fragments ''lock'' in place and thereby bridge the opening. In such cases, the peak stresses at the flaw site can increase, leading to further (i.e. secondary) crack growth

  17. Multiphoton laser-induced-fluorescence studies of simple species

    International Nuclear Information System (INIS)

    Recent studies have demonstrated multiple-photon excitation of atomic species. Bischel and coworkers have provided a detailed description of two-photon excitation fluorescence in the detection of atoms generated in a low pressure discharge and its possible application as a diagnostic tool in flame and plasmas. It is also believed that such techniques can be useful in detecting molecular transients which are difficult to detect otherwise as demonstrated in two-photon laser-induced fluorescence (LIF) detection of NO. In this paper, we discuss our recent two-photon LIF studies on I and Br atoms, which are produced via laser photolysis of molecular precursors. The two-photon LIF study of HS and DS radicals is presented as a test case for the detection of other important radical species such as C2H and CH3, which are currently being investigated in our laboratory. In addition, excitation of three-photon resonances of I2, N2, and H2 is discussed

  18. Topical application of PPADS inhibits complement activation and choroidal neovascularization in a model of age-related macular degeneration.

    Directory of Open Access Journals (Sweden)

    Kerstin Birke

    Full Text Available Age-related macular degeneration (AMD is the most common cause of blindness among the elderly. AMD patients have elevated levels of membrane attack complex (MAC in their choroidal blood vessels and retinal pigment epithelium (RPE. MAC forms pores in cell membranes. Low levels of MAC result in an elevation of cytokine release such as vascular endothelial growth factor (VEGF that promotes the formation of choroidal neovascularization (CNV. High levels of MAC result in cell lysis and RPE degeneration is a hallmark of advanced AMD. The current standard of care for CNV associated with wet AMD is intravitreal injection of anti-VEGF molecules every 4 to 12 weeks. Such injections have significant side effects. Recently, it has been found that membrane pore-forming proteins such as α-haemolysin can mediate their toxic effects through auto- and paracrine signaling and that complement-induced lysis is amplified through ATP release followed by P2X receptor activation. We hypothesized that attenuation of P2X receptor activation may lead to a reduction in MAC deposition and consequent formation of CNV. Hence, in this study we investigated topical application of the purinergic P2X antagonist Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS as a potential treatment for AMD. We found that 4.17 µM PPADS inhibited formation of HUVEC master junctions and master segments by 74.7%. In a human complement mediated cell lysis assay, 104 µM PPADS enabled almost complete protection of Hepa1c1c7 cells from 1% normal human serum mediated cell lysis. Daily topical application of 4.17 mM PPADS for 3 days attenuated the progression of laser induced CNV in mice by 41.8% and attenuated the deposition of MAC at the site of the laser injury by 19.7%. Our data have implications for the future treatment of AMD and potentially other ocular disorders involving CNV such as angioid streaks, choroidal rupture and high myopia.

  19. Influx mechanisms in the embryonic and adult rat choroid plexus

    DEFF Research Database (Denmark)

    Saunders, Norman R; Dziegielewska, Katarzyna M; Møllgård, Kjeld;

    2015-01-01

    The transcriptome of embryonic and adult rat lateral ventricular choroid plexus, using a combination of RNA-Sequencing and microarray data, was analyzed by functional groups of influx transporters, particularly solute carrier (SLC) transporters. RNA-Seq was performed at embryonic day (E) 15 and a...... studies suggests that the choroid plexus in embryonic brain plays a major role in supplying the developing brain with essential nutrients.......The transcriptome of embryonic and adult rat lateral ventricular choroid plexus, using a combination of RNA-Sequencing and microarray data, was analyzed by functional groups of influx transporters, particularly solute carrier (SLC) transporters. RNA-Seq was performed at embryonic day (E) 15 and...... in the adult plexus were expressed at higher levels than in embryos. These results are compared with earlier published physiological studies of amino acid and monocarboxylate transport in developing rodents. This comparison shows correlation of high expression of some transporters in the developing...

  20. Optical Coherence Tomography of Retinal and Choroidal Tumors

    Directory of Open Access Journals (Sweden)

    Emil Anthony T. Say

    2011-01-01

    Full Text Available Optical coherence tomography (OCT has revolutionized the field of ophthalmology since its introduction 20 years ago. Originally intended primarily for retina specialists to image the macula, it has found its role in other subspecialties that include glaucoma, cornea, and ocular oncology. In ocular oncology, OCT provides axial resolution to approximately 7 microns with cross-sectional images of the retina, delivering valuable information on the effects of intraocular tumors on the retinal architecture. Some effects include retinal edema, subretinal fluid, retinal atrophy, photoreceptor loss, outer retinal thinning, and retinal pigment epithelial detachment. With more advanced technology, OCT now provides imaging deeper into the choroid using a technique called enhanced depth imaging. This allows characterization of the thickness and reflective quality of small (<3 mm thick choroidal lesions including choroidal nevus and melanoma. Future improvements in image resolution and depth will allow better understanding of the mechanisms of visual loss, tumor growth, and tumor management.

  1. Diagnostic imaging of choroid plexus disease pictorial review

    Energy Technology Data Exchange (ETDEWEB)

    Guermazi, A.; De Kerviler, E.; Zagdanski, A.-M.; Frija, J

    2000-07-01

    Disorders of the choroid plexus, a central nervous system structure, are rare, but can pose diagnostic difficulties. The purpose of this review is to illustrate the computed tomography and magnetic resonance imaging findings of a wide spectrum of lesions that affect the choroid plexus. The areas covered include (1) neoplasms (papilloma, leukaemia, meningioma, lymphoma and metastases); (2) infections (bacterial, fungal and viral); (3) cysts; (4) haemorrhage; (5) congenital abnormalities (Sturge-Weber syndrome, Klippel-Trenaunay-Weber syndrome and vascular malformations); and (6) non-infectious inflammatory disorders (xanthogranulomas, inflammatory pseudotumour, neurosarcoidosis, rheumatoid nodule and villous hypertrophy). Few of the patterns of choroid plexus involvement are specific for a particular pathological process. Guermazi, A. (2000)

  2. Influence of Crystallinity on the Bulk Laser-Induced Damage Threshold and Absorption of Laser Light in CsLiB6O10 Crystals

    Science.gov (United States)

    Kamimura, Tomosumi; Ono, Richi; Yap, Yoke Khin; Yoshimura, Masashi; Mori, Yusuke; Sasaki, Takatomo

    2001-02-01

    The relationships among the bulk laser-induced damage threshold (LIDT), dislocation density and absorption of laser light in CsLiB6O10 (CLBO) were investigated. A newly developed synthesis process allows the growth of CLBO crystals with a LIDT of 2.5-fold higher than that grown by the conventional top-seeded solution growth (TSSG) technique. High-quality CLBO possesses lower dislocation density (6.6× 103/cm2) than conventional CLBO (˜ 15.0× 103/cm2). The absorption of laser light in CLBO was characterized by measuring the temperature increase on the crystal output surface during the generation of fourth-harmonic (@266 nm) light of Nd:YAG lasers. At a UV power of 5 W, the maximum temperature increase was 6°C for high-quality CLBO, which was ˜ 30% lower than that generated on conventional CLBO crystal. Thus, the reduction of dislocation density can suppress the absorption of laser light, which helps to enhance the resistance of CLBO against laser-induced damage and alleviate thermal dephasing during the high-power generation of UV light.

  3. Islam, Globalization, and Poverty Alleviation

    Directory of Open Access Journals (Sweden)

    Dwi Sulastyawati

    2015-11-01

    Full Text Available Globalization is globab as well condition and situation, neither economically, politically, and socially. All countries that embrace open economic system have participated in the system of globalization. Today the world is under the influence of super power world. For instance, using dollar as the official currency for international transactions, so that dollar dominates in international transactions. As a result, the value of the debt of developing countries has increased due to the rising price of dollar. The increment of the debt value in developing countries led the government reduces subsidies for the community. Thus economic hardship perceived more and more for poor people. This resulted that poverty is hard to be alleviated. This article analyzes the various Islamic perspective and thoughts on the impact of globalization on poverty alleviation.DOI: 10.15408/aiq.v5i2.2123

  4. A Combined Mathematical-Physical Model of Laser-Induced Thermotherapy (LITT)

    DEFF Research Database (Denmark)

    Enevoldsen, Marie Sand; Skovgaard, Ove; Andersen, Peter E.

    2009-01-01

    Laser{induced thermo therapy (LITT) is an alternative, gentle therapy of cancer. In this work a new computa- tional model (3D space and time) of LITT is presented. Using an arbitrary small number (... treatment....

  5. Laser-induced multi-point ignition for enabling high-performance engines

    KAUST Repository

    Chung, Suk-Ho

    2015-01-01

    Various multi-point laser-induced ignition techniques were reviewed, which adopted conical cavity and prechamber configurations. Up to five-point ignitions have been achieved with significant reduction in combustion duration, demonstrating potential increase in combustion system efficiency.

  6. Red-shift law of intense laser-induced electro-absorption in solids

    Science.gov (United States)

    Deng, Hong-Xiang; Zu, Hao-Yue; Wu, Shao-Yi; Sun, Kai; Zu, Xiao-Tao

    2014-02-01

    A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and has an obvious deviation from this scale in the multi-photon regime. Our results show that in the optical tunneling regime, the laser-induced red shift has the same law as that in the direct current (DC) approximation. Though the scales are the same in the optical tunneling regime, the physical pictures in the two cases are quite different. The electro-absorption in the DC case is a tunneling-assisted transition process, while the laser-induced electro-absorption is a mixed multi-photon process.

  7. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    Science.gov (United States)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  8. Laser-Induced Emissions Sensor for Soot Mass in Rocket Plumes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A method is proposed to measure soot mass concentration non-intrusively from a distance in a rocket engine exhaust stream during ground tests using laser-induced...

  9. Mid-infrared Molecular Emission Studies from Energetic Materials using Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Brown, Ei; Hommerich, Uwe; Yang, Clayton; Trivedi, Sudhir; Samuels, Alan; Snyder, Peter

    2011-10-01

    Laser-induced breakdown spectroscopy (LIBS) is a powerful diagnostic tool for detection of trace elements by monitoring the atomic and ionic emission from laser-induced plasmas. The laser-induced plasma was produced by focusing a 30 mJ pulsed Nd:YAG laser (1064 nm) to dissociate, atomize, and ionize target molecules. In this work, LIBS emissions in the mid-infrared (MIR) region were studied for potential applications in chemical, biological, and explosives (CBE) sensing. We report on the observation of MIR emissions from energetic materials (e.g. ammonium compounds) due to laser-induced breakdown processes. All samples showed LIBS-triggered oxygenated breakdown products as well as partially dissociated and recombination molecular species. More detailed results of the performed MIR LIBS studies on the energetic materials will be discussed at the conference.

  10. Clinical characteristics and treatment of neurofibroma of the choroid

    Institute of Scientific and Technical Information of China (English)

    WEI Wen-bin; JIE Ying; MO Jing; LI Bin

    2012-01-01

    Background Neurofibroma is a kind of benign neoplasm that derives from nervous tissues.Though this tumor is the most common types in the peripheral nervous system,it is rarely seen in the choroid and easy to be misdiagnosed of choroidal melanoma.The aim of this study was to review the clinical features of neurofibroma of the choroid in the Chinese race.Methods A retrospective case series design was used.Two male and one female patients diagnosed with choroidal neurofibroma in Beijing Tongren Eye Center were included in this study.The clinical histories were abstracted from the patients' medical records.Routine eye examinations including visual acuity,intraocular pressure,slit lamp and ophthalmoscope were performed.Auxiliary examinations included fluorescein fundus angiography (FFA),AB-ultrasound scan,color doppler imaging (CDI),and magnetic resonance imaging (MRI).Local resection of the tumors was performed and the specimens underwent pathological examinations.Results The tumors were of yellow-pink color with pigmentation on the surface.CDI showed arterial blood signals in the tumor and MRI showed high-intensity in the T1-weighted image and a slightly increased intensity in the T2-weighted image.FFA and indocyaninegreen angiography demonstrated the tumors were of hypofluorescence at early stage and hyperfluorescence with prominent leakage at late stage.The pathological examination confirmed the tumors were choroidal neurofibroma.After 5-10-year follow-up,there were no recurrences of the tumors and the retinas were well attached.Conclusions Choroidal neurofibroma is difficult to be diagnosed clinically and pathological confirmation is important.These tumors can be managed conservatively by local resection.

  11. Microstructural effects of intravitreal bevacizumab in idiopathic choroidal neovascularisation

    International Nuclear Information System (INIS)

    Idiopathic choroidal neovascularization (ICNV) is a unilateral ocular disease which occurs in patients younger than 50 years and accounts for approximately 17% of patients with CNV. We evaluated microstructural effects of intravitreal bevacizumab in eyes with treatment-naive idiopathic choroidal neovascularisation. Methods: In this case series study we reviewed the treatment and follow up records of 40 symptomatic eyes having ICNV, who received an intravitreal injection of bevacizumab (1.25 mg/0.05 mL) followed by additional doses based on optical coherence tomography findings, including intraretinal fluid, subretinal fluid, or pigment epithelial detachment. We analysed the results of best-corrected visual acuity, central retinal thickness, neovessels size (thickness and diameter), and disrupted photoreceptor length at baseline and at final visit with paired t-test. Difference in best corrected visual acuity was correlated with difference in optical coherence tomography parameters by Pearson's correlation. Results: Mean logarithm of the minimum angle of resolution best-corrected visual acuity improved from 0.60 initially to 0.24 after treatment (p=0.01). Difference in mean central retinal thickness (82.65 ± 44.1) micro m, choroidal neovessels thickness (149.58 ± 71.1) micro m, choroidal neovessels diameter (1250.8 ± 145.1) micro m, photoreceptor disruption length (2141.20 ± 318.8) micro m were all statistically significant (p=0.01). Difference in best corrected visual acuity was correlated with optical coherence tomography parameters found no statistically significant difference. Conclusion: Intravitreal bevacizumab therapy is safe and well tolerated in ICNV eyes. Restoration of photoreceptor disruption length, decrease in central retinal thickness and choroidal neovessels size has association with visual improvement in idiopathic choroidal neovascularisation. (author)

  12. Simultaneous measurement of Raman scattering and laser-induced OH fluorescence in nonpremixed turbulent jet flames.

    Science.gov (United States)

    Barlow, R S; Dibble, R W; Lucht, R P

    1989-03-01

    Spontaneous Raman scattering and laser-induced fluorescence are combined to perform simultaneous point measurements of major species concentrations, temperature, and hydroxyl radical concentration in turbulent nonpremixed flames. The Raman-scattering data for major species concentrations and temperature characterize the instantaneous, local, collisional quenching environment of the OH molecule. Collisional quenching corrections are applied for each laser shot so that absolute hydroxyl concentrations are obtained in turbulent flames using linear laser-induced fluorescence. PMID:19749889

  13. Origin of Plateau and Species dependence of Laser-Induced High-Energy Photoelectron Spectra

    OpenAIRE

    Chen, Zhangjin; Le, Anh-Thu; Morishita, Toru; Lin, C. D.

    2008-01-01

    We analyzed the energy and momentum distributions of laser-induced high-energy photoelectrons of alkali and rare gas atoms. For the plateau electrons with energies above $4U_p$, ($U_p$ is the ponderomotive energy), in the tunneling ionization regime, we showed that they originate from the backscattering of laser-induced returning electrons. Using the differential elastic scattering cross sections between the target ion with \\emph{free} electrons, we explain experimental observations of whethe...

  14. Reflectance, scattering, and laser induced fluorescence for the detection of dental caries

    Science.gov (United States)

    Drakaki, Eleni; Makropoulou, Myrsini; Khabbaz, Maruan; Serafetinides, Alexandros A.

    2003-10-01

    Directional dependence of reflected laser light and of the laser induced fluorescence signals performed both on the intact hard dental tissues, such as enamel, dentine, cementum and on the tissues pathologically affected by caries (superficial, intermediate, and deep). The laser induced fluorescence spectra were collected at different angles of observation and were correlated with the different scattering and reflectance properties of the hard dental samples

  15. Analysis of geological samples by laser-induced breakdown spectroscopy at low atmospheric pressures

    OpenAIRE

    Pavlov, S.G.; Schröder, Susanne; Jessberger, E.K.; Hübers, H.-W.

    2011-01-01

    Several future space missions to planets, moons and asteroids in the solar system consider landers equip-ped with a laser-induced breakdown spectroscopy (LIBS) instrument. This technique provides an in-situ elemental analysis of all major and many trace elements on surfaces of the solar system bodies by identification of particular atomic transitions in emission spectra of laser-induced plasmas. Excitation and evolution of the plasma depends strongly on the environmental pressure. Therefore, ...

  16. Properties and Applications of Laser-Induced Gratings in Rare Earth Doped Glasses.

    Science.gov (United States)

    Behrens, Edward Grady

    Scope and method of study. Four-wave-mixing techniques were used in an attempt to create permanent laser-induced grating in Pr^{3+}-, Nd ^{3+}-, Eu^ {3+}-, and Er^{3+ }-doped glasses. The permanent laser-induced grating signal intensity and build-up and erase times were investigated as function of the write beam crossing angle, write beam power, and temperature. Thermal lensing measurements were conducted on Eu^{3+} - and Nd^{3+}-doped glasses and room temperature Raman and resonant Raman spectra were obtained for Eu^{3+}-doped glasses. The permanent laser-induced grating signal intensity was studied in Eu^{3+} -doped alkali-metal glasses as a function of the alkali -metal network modifier ion and a model was developed by treating the sample as a two-level system. Optical device applications of the permanent laser-induced gratings were studied by creating some simple devices. Findings and conclusions. Permanent laser-induced gratings were created in the Pr^{3+ }- and Eu^{3+} -doped glasses. The permanent laser-induced grating is associated with a structural phase change of the glass host. The structural change is produced by high energy phonons which are emitted by radiationless relaxation processes of the rare earth ion. Nd^{3+} and Er^{3+} relax nonradiatively by the emission of phonons of much lower energy which are unable to produce the structural phase change needed to form a permanent laser-induced grating. The difference in energy of the emitted phonons is responsible for the differing characteristics of the thermal lensing experiments. The model does a good job of predicting the experimental results for the asymmetry and other parameters of the two-level system. The application of these laser -induced gratings for optical devices demonstrates their importance to optical technology.

  17. Laser-Induced Point Defects in Fused Silica Irradiated by UV Laser in Vacuum

    OpenAIRE

    Xiaoyan Zhou; Xinda Zhou; Jin Huang; Qiang Cheng; Fengrui Wang; Xin Ye; Xiaodong Jiang; Weidong Wu

    2014-01-01

    High-purity fused silica irradiated by third harmonic of the Nd:YAG laser in vacuum with different laser pulse parameters was studied experimentally. Laser-induced defects are investigated by UV spectroscopy, and fluorescence spectra and correlated to the structural modifications in the glass matrix through Raman spectroscopy. Results show that, for laser fluence below laser-induced damage threshold (LIDT), the absorbance and intensity of fluorescence bands increase with laser energies and/or...

  18. Laser-induced pattern formation in liquid sulfur. An indication of laser-induced phase transition to ordered polymer

    Science.gov (United States)

    Sakaguchi, Y.; Tamura, K.

    2007-04-01

    Liquid sulfur is a well-known liquid which exhibits a polymerization transition at T_p=159 °C. Recently, it was found from our experiments that such a transition can be induced below Tp through laser illumination and that an iridescent pattern appears under strong illumination with a pulsed laser of more than 60 mJ/cm2 pulse. It is proposed that the visible change in iridescence is due to a macroscopic reconstruction of laser-generated polymers and that a laser-induced phase transition takes place from a freely expanded polymer phase to an ordered polymer phase when increasing the laser illumination. To further examine this possibility, the time variation of the iridescent pattern has been fully investigated using a macro lens, a polarized microscope and an optical microscope. In an analysis of the iridescent pattern, a rapid decrease in the area was observed after an initial slow decrease, suggesting a type of phase transition. Results from the observation of a quenched sulfur sample with a polarized microscope gave evidence that the iridescent region consists of polymers. Through observation of the liquid with a microscope, a striped pattern with micrometer sized spacing was noted in the iridescent pattern. A drastic color change was observed in the pattern from its generation to its disappearance. Sample thickness dependence of the pattern was also observed. These results were well explained by assuming the self-arrangement of laser-generated colloidal polymers.

  19. Endogenous nitric oxide mediates He-Ne laser-induced adaptive responses in salt stressed-tall fescue leaves.

    Science.gov (United States)

    Li, Yongfeng; Gao, Limei; Han, Rong

    2016-10-01

    The aim of this study was to investigate the role of endogenous nitric oxide in protective effects of He-Ne laser on salt stressed-tall fescue leaves. Salt stress resulted in significant increases of membrane injury, reactive oxygen species (ROS) production, polyamine accumulation, and activities of SOD, POD, and APX, while pronounced decreases of antioxidant contents, CAT activity and intracellular Ca(2+) concentration in seedlings leaves. He-Ne laser illumination caused a distinct alleviation of cellular injury that was reflected by the lower MDA amounts, polyamine accumulation and ROS levels at the stress period. In contrast, the laser treatment displayed a higher Ca(2+) concentration, antioxidant amounts, NO release, antioxidant enzyme, and NOS activities. These responses could be blocked due to the inhibition of NO biosynthesis by PTIO (NO scavenger) or LNNA (NOS inhibitor). The presented results demonstrated that endogenous NO might be involved in the progress of He-Ne laser-induced plant antioxidant system activation and ROS degradation in order to enhance adaptive responses of tall fescue to prolonged saline conditions. PMID:27309569

  20. Multivariate Analysis of Laser-Induced Breakdown Spectroscopy for Discrimination between Explosives and Plastics

    Institute of Scientific and Technical Information of China (English)

    WANG Qian-Qian; LIU Kai; ZHAO Hua

    2012-01-01

    A method to distinguish explosives from plastics using laser-induced breakdown spectroscopy is discussed. A model for classification with cross-validation theory is built based on the partial least-square discriminant analysis method. Seven types of plastics and one explosive are used as samples to test the model. The experimental results demonstrate that laser-induced breakdown spectroscopy has the capacity to discriminate explosives from plastics combined with chemometrics methods. The results could be useful for prospective research of laser-induced breakdown spectroscopy on the differentiation of explosives and other materials.%A method to distinguish explosives from plastics using laser-induced breakdown spectroscopy is discussed.A model for classification with cross-validation theory is built based on the partial least-square discriminant analysis method.Seven types of plastics and one explosive are used as samples to test the model.The experimental results demonstrate that laser-induced breakdown spectroscopy has the capacity to discriminate explosives from plastics combined with chemometrics methods.The results could be useful for prospective research of laser-induced breakdown spectroscopy on the differentiation of explosives and other materials.

  1. Laser induced x-ray `RADAR' particle physics model

    Science.gov (United States)

    Lockley, D.; Deas, R.; Moss, R.; Wilson, L. A.; Rusby, D.; Neely, D.

    2016-05-01

    The technique of high-power laser-induced plasma acceleration can be used to generate a variety of diverse effects including the emission of X-rays, electrons, neutrons, protons and radio-frequency radiation. A compact variable source of this nature could support a wide range of potential applications including single-sided through-barrier imaging, cargo and vehicle screening, infrastructure inspection, oncology and structural failure analysis. This paper presents a verified particle physics simulation which replicates recent results from experiments conducted at the Central Laser Facility at Rutherford Appleton Laboratory (RAL), Didcot, UK. The RAL experiment demonstrated the generation of backscattered X-rays from test objects via the bremsstrahlung of an incident electron beam, the electron beam itself being produced by Laser Wakefield Acceleration. A key initial objective of the computer simulation was to inform the experimental planning phase on the predicted magnitude of the backscattered X-rays likely from the test objects. This objective was achieved and the computer simulation was used to show the viability of the proposed concept (Laser-induced X-ray `RADAR'). At the more advanced stages of the experimental planning phase, the simulation was used to gain critical knowledge of where it would be technically feasible to locate key diagnostic equipment within the experiment. The experiment successfully demonstrated the concept of X-ray `RADAR' imaging, achieved by using the accurate timing information of the backscattered X-rays relative to the ultra-short laser pulse used to generate the electron beam. By using fast response X-ray detectors it was possible to derive range information for the test objects being scanned. An X-ray radar `image' (equivalent to a RADAR B-scan slice) was produced by combining individual X-ray temporal profiles collected at different points along a horizontal distance line scan. The same image formation process was used to generate

  2. A handheld laser-induced fluorescence detector for multiple applications.

    Science.gov (United States)

    Fang, Xiao-Xia; Li, Han-Yang; Fang, Pan; Pan, Jian-Zhang; Fang, Qun

    2016-04-01

    In this paper, we present a compact handheld laser-induced fluorescence (LIF) detector based on a 450nm laser diode and quasi-confocal optical configuration with a total size of 9.1×6.2×4.1cm(3). Since there are few reports on the use of 450nm laser diode in LIF detection, especially in miniaturized LIF detector, we systematically investigated various optical arrangements suitable for the requirements of 450nm laser diode and system miniaturization, including focusing lens, filter combination, and pinhole, as well as Raman effect of water at 450nm excitation wavelength. As the result, the handheld LIF detector integrates the light source (450nm laser diode), optical circuit module (including a 450nm band-pass filter, a dichroic mirror, a collimating lens, a 525nm band-pass filter, and a 1.0mm aperture), optical detector (miniaturized photomultiplier tube), as well as electronic module (including signal recording, processing and displaying units). This detector is capable of working independently with a cost of ca. $2000 for the whole instrument. The detection limit of the instrument for sodium fluorescein solution is 0.42nM (S/N=3). The broad applicability of the present system was demonstrated in capillary electrophoresis separation of fluorescein isothiocyanate (FITC) labeled amino acids and in flow cytometry of tumor cells as an on-line LIF detector, as well as in droplet array chip analysis as a LIF scanner. We expect such a compact LIF detector could be applied in flow analysis systems as an on-line detector, and in field analysis and biosensor analysis as a portable universal LIF detector. PMID:26838391

  3. Laser-induced fluorescence in diagnosis of dental caries

    Science.gov (United States)

    Drakaki, Eleni A.; Makropoulou, Mersini I.; Khabbaz, Maruan; Serafetinides, Alexandros A.

    2003-09-01

    laser induces better discrimination in deep caries diagnosis.

  4. Laser Induced Fluorescence Diagnostic for the ASTRAL Plasma Source.

    Science.gov (United States)

    Boivin, Robert; Kamar, Ola; Munoz, Jorge

    2006-10-01

    A Laser Induced Fluorescence (LIF) diagnostic is presented in this poster. The ion temperature measurements are made in the ASTRAL (Auburn Steady sTate Research fAciLity) helicon plasma source using a diode laser based LIF diagnostic. ASTRAL produces Ar plasmas with the following parameters: ne = 10^10 to 10^13 cm-3, Te = 2 to 10 eV and Ti = 0.03 to 0.5 eV. A series of 7 large coils produce an axial magnetic field up to 1.3 kGauss. Operating pressure varies from 0.1 to 100 mTorr and any gas can be used for the discharge. A fractional helix antenna is used to introduce rf power up to 2 kWatt. A number of diagnostics are presently installed on the plasma device (Langmuir Probe, Spectrometer, LIF system). The LIF diagnostic makes use of a diode laser with the following characteristics: 1.5 MHz bandwidth, Littrow external cavity, mode-hop free tuning range up to 16 GHz, total power output of about 15 mW. The wavelength is measured by a precision wavemeter and frequent monitoring prevents wavelength drift. For Ar plasma, a new LIF scheme has been developed. The laser tuned at 686.354 nm, is used to pump the 3d^4F5/2 Ar II metastable level to the 4p^4D5/2 state. The fluorescence radiation between the 4p^4D5/2 and the 4s^4P3/2 terms (442.6 nm) is monitored by a PMT.

  5. Application of Laser Induced Breakdown Spectroscopy under Polar Conditions

    Science.gov (United States)

    Clausen, J. L.; Hark, R.; Bol'shakov, A.; Plumer, J.

    2015-12-01

    Over the past decade our research team has evaluated the use of commercial-off-the-shelf laser-induced breakdown spectroscopy (LIBS) for chemical analysis of snow and ice samples under polar conditions. One avenue of research explored LIBS suitability as a detector of paleo-climate proxy indicators (Ca, K, Mg, and Na) in ice as it relates to atmospheric circulation. LIBS results revealed detection of peaks for C and N, consistent with the presence of organic material, as well as major ions (Ca, K, Mg, and Na) and trace metals (Al, Cu, Fe, Mn, Ti). The detection of Ca, K, Mg, and Na confirmed that LIBS has sufficient sensitivity to be used as a tool for characterization of paleo-climate proxy indicators in ice-core samples. Techniques were developed for direct analysis of ice as well as indirect measurements of ice via melting and filtering. Pitfalls and issues of direct ice analysis using several cooling techniques to maintain ice integrity will be discussed. In addition, a new technique, laser ablation molecular isotopic spectroscopy (LAMIS) was applied to detection of hydrogen and oxygen isotopes in ice as isotopic analysis of ice is the main tool in paleoclimatology and glaciology studies. Our results demonstrated that spectra of hydroxyl isotopologues 16OH, 18OH, and 16OD can be recorded with a compact spectrograph to determine hydrogen and oxygen isotopes simultaneously. Quantitative isotopic calibration for ice analysis can be accomplished using multivariate chemometric regression as previously realized for water vapor. Analysis with LIBS and LAMIS required no special sample preparation and was about ten times faster than analysis using ICP-MS. Combination of the two techniques in one portable instrument for in-field analysis appears possible and would eliminate the logistical and cost issues associated with ice core management.

  6. Independent component analysis classification of laser induced breakdown spectroscopy spectra

    International Nuclear Information System (INIS)

    The ChemCam instrument on board Mars Science Laboratory (MSL) rover uses the laser-induced breakdown spectroscopy (LIBS) technique to remotely analyze Martian rocks. It retrieves spectra up to a distance of seven meters to quantify and to quantitatively analyze the sampled rocks. Like any field application, on-site measurements by LIBS are altered by diverse matrix effects which induce signal variations that are specific to the nature of the sample. Qualitative aspects remain to be studied, particularly LIBS sample identification to determine which samples are of interest for further analysis by ChemCam and other rover instruments. This can be performed with the help of different chemometric methods that model the spectra variance in order to identify a the rock from its spectrum. In this paper we test independent components analysis (ICA) rock classification by remote LIBS. We show that using measures of distance in ICA space, namely the Manhattan and the Mahalanobis distance, we can efficiently classify spectra of an unknown rock. The Mahalanobis distance gives overall better performances and is easier to manage than the Manhattan distance for which the determination of the cut-off distance is not easy. However these two techniques are complementary and their analytical performances will improve with time during MSL operations as the quantity of available Martian spectra will grow. The analysis accuracy and performances will benefit from a combination of the two approaches. - Highlights: • We use a novel independent component analysis method to classify LIBS spectra. • We demonstrate the usefulness of ICA. • We report the performances of the ICA classification. • We compare it to other classical classification schemes

  7. Measuring atmospheric naphthalene with laser-induced fluorescence

    Directory of Open Access Journals (Sweden)

    M. Martinez

    2004-01-01

    Full Text Available A new method for measuring gas-phase naphthalene in the atmosphere is based on laser-induced fluorescence at low pressure. The fluorescence spectrum of naphthalene near 308 nm was identified. Naphthalene fluorescence quenching by N2, O2 and H2O was investigated in the laboratory. No significant quenching was found for H2O with mixing ratio up to 2.5%. The quenching rate of naphthalene fluorescence is (1.98±0.18×10−11 cm3 molecule−1 s−1 for N2, and (2.48±0.08×10−10 cm3 molecule−1 s−1 for O2 at 297 K. Instrument calibrations were performed with a range of naphthalene mixing ratios between 5 and 80 parts per billion by volume (ppbv, 10−9. In the current instrument configuration, the detection limit is estimated to be about 20 parts per trillion by volume (pptv, 10−12 with 2σ confidence and a 1-min integration time. Measurement of atmospheric naphthalene in three cities, Nashville, TN, Houston, TX, and New York City, NY, are presented. Good correlation between naphthalene and major anthropogenic pollutants is found.

  8. Characterization Of High Explosives Detonations Via Laser-Induced Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Aleman, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    One objective of the Department of Energy’s National Security Administration is to develop technologies that can help the United States government to detect foreign nuclear weapons development activities. The realm of high explosive (HE) experiments is one of the key areas to assess the nuclear ambitions of a country. SRNL has participated in the collection of particulates from HE experiments and characterized the material with the purpose to correlate particulate matter with HE. Since these field campaigns are expensive, on-demand simulated laboratory-scale explosion experiments are needed to further our knowledge of the chemistry and particle formation in the process. Our goal is to develop an experimental test bed in the laboratory to test measurement concepts and correlate particle formation processes with the observables from the detonation fireball. The final objective is to use this knowledge to tailor our experimental setups in future field campaigns. The test bed uses pulsed laser-induced plasmas to simulate micro-explosions, with the intent to study the temporal behavior of the fireball observed in field tests. During FY15, a plan was prepared and executed which assembled two laser ablation systems, procured materials for study, and tested a Step-Scan Fourier Transform Infrared Spectrometer (SS-FTIR). Designs for a shadowgraph system for shock wave analysis, design for a micro-particulate collector from ablated pulse were accomplished. A novel spectroscopic system was conceived and a prototype system built for acquisition of spectral/temporal characterization of a high speed event such as from a high explosive detonation. Experiments and analyses will continue into FY16.

  9. Detection of uranium using laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Chinni, Rosemarie C; Cremers, David A; Radziemski, Leon J; Bostian, Melissa; Navarro-Northrup, Claudia

    2009-11-01

    The goal of this work is a detailed study of uranium detection by laser-induced breakdown spectroscopy (LIBS) for application to activities associated with environmental surveillance and detecting weapons of mass destruction (WMD). The study was used to assist development of LIBS instruments for standoff detection of bulk radiological and nuclear materials and these materials distributed as contaminants on surfaces. Uranium spectra were analyzed under a variety of different conditions at room pressure, reduced pressures, and in an argon atmosphere. All spectra displayed a high apparent background due to the high density of uranium lines. Time decay curves of selected uranium lines were monitored and compared to other elements in an attempt to maximize detection capabilities for each species in the complicated uranium spectrum. A survey of the LIBS uranium spectra was conducted and relative emission line strengths were determined over the range of 260 to 800 nm. These spectra provide a guide for selection of the strongest LIBS analytical lines for uranium detection in different spectral regions. A detection limit for uranium in soil of 0.26% w/w was obtained at close range and 0.5% w/w was achieved at a distance of 30 m. Surface detection limits were substrate dependent and ranged from 13 to 150 microg/cm2. Double-pulse experiments (both collinear and orthogonal arrangements) were shown to enhance the uranium signal in some cases. Based on the results of this work, a short critique is given of the applicability of LIBS for the detection of uranium residues on surfaces for environmental monitoring and WMD surveillance. PMID:19891832

  10. Characterisation of estuarine intertidal macroalgae by laser-induced fluorescence

    Science.gov (United States)

    Gameiro, Carla; Utkin, Andrei B.; Cartaxana, Paulo

    2015-12-01

    The article reports the application of laser-induced fluorescence (LIF) for the assessment of macroalgae communities of estuarine intertidal areas. The method was applied for the characterisation of fifteen intertidal macroalgae species of the Tagus estuary, Portugal, and adjacent coastal area. Three bands characterised the LIF spectra of red macroalgae with emission maxima in the ranges 577-583 nm, 621-642 nm and 705-731 nm. Green and brown macroalgae showed one emission maximum in the red region (687-690 nm) and/or one in the far-red region (726-732 nm). Characteristics of LIF emission spectra were determined by differences in the main fluorescing pigments: phycoerythrin, phycocyanin and chlorophyll a (Chl a). In the green and brown macroalgae groups, the relative significance of the two emission maxima seems to be related to the thickness of the photosynthetic layer. In thick macroalgae, like Codium tomentosum or Fucus vesiculosus, the contribution of the far-red emission fluorescence peak was more significant, most probably due to re-absorption of the emitted red Chl a fluorescence within the dense photosynthetic layer. Similarly, an increase in the number of layers of the thin-blade green macroalgae Ulva rigida caused a shift to longer wavelengths of the red emission maximum and the development of a fluorescence peak at the far-red region. Water loss from Ulva's algal tissue also led to a decrease in the red/far-red Chl fluorescence ratio (F685/F735), indicating an increase in the density of chloroplasts in the shrinking macroalgal tissue during low tide exposure.

  11. Laser-induced selective copper plating of polypropylene surface

    Science.gov (United States)

    Ratautas, K.; Gedvilas, M.; Stankevičiene, I.; JagminienÄ--, A.; Norkus, E.; Li Pira, N.; Sinopoli, S.; Emanuele, U.; Račiukaitis, G.

    2016-03-01

    Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

  12. Independent component analysis classification of laser induced breakdown spectroscopy spectra

    Energy Technology Data Exchange (ETDEWEB)

    Forni, Olivier, E-mail: olivier.forni@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Maurice, Sylvestre, E-mail: sylvestre.maurice@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Gasnault, Olivier, E-mail: olivier.gasnault@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Wiens, Roger C., E-mail: rwiens@lanl.gov [Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Cousin, Agnès, E-mail: acousin@lanl.gov [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Chemical Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Clegg, Samuel M., E-mail: sclegg@lanl.gov [Chemical Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Sirven, Jean-Baptiste, E-mail: jean-baptiste.sirven@cea.f [CEA Saclay, DEN/DPC/SCP, 91191 Cedex, Gif sur Yvette (France); Lasue, Jérémie, E-mail: jeremie.lasue@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France)

    2013-08-01

    The ChemCam instrument on board Mars Science Laboratory (MSL) rover uses the laser-induced breakdown spectroscopy (LIBS) technique to remotely analyze Martian rocks. It retrieves spectra up to a distance of seven meters to quantify and to quantitatively analyze the sampled rocks. Like any field application, on-site measurements by LIBS are altered by diverse matrix effects which induce signal variations that are specific to the nature of the sample. Qualitative aspects remain to be studied, particularly LIBS sample identification to determine which samples are of interest for further analysis by ChemCam and other rover instruments. This can be performed with the help of different chemometric methods that model the spectra variance in order to identify a the rock from its spectrum. In this paper we test independent components analysis (ICA) rock classification by remote LIBS. We show that using measures of distance in ICA space, namely the Manhattan and the Mahalanobis distance, we can efficiently classify spectra of an unknown rock. The Mahalanobis distance gives overall better performances and is easier to manage than the Manhattan distance for which the determination of the cut-off distance is not easy. However these two techniques are complementary and their analytical performances will improve with time during MSL operations as the quantity of available Martian spectra will grow. The analysis accuracy and performances will benefit from a combination of the two approaches. - Highlights: • We use a novel independent component analysis method to classify LIBS spectra. • We demonstrate the usefulness of ICA. • We report the performances of the ICA classification. • We compare it to other classical classification schemes.

  13. Analysis of slags using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Sanghapi, Hervé K.; Ayyalasomayajula, Krishna K.; Yueh, Fang Y.; Singh, Jagdish P.; McIntyre, Dustin L.; Jain, Jinesh C.; Nakano, Jinichiro

    2016-01-01

    The feasibility of laser-induced breakdown spectroscopy (LIBS) for the analysis of gasification slags was investigated by comparing LIBS results to the results of an ICP-OES analyzer. A small amount of slag sample was placed on a piece of double sided adhesive tape attached to a glass microscope slide and analyzed for Al, Ca, Fe, Si, and V which are major elements found in slags. The partial least squares regression (PLS-R) and univariate simple linear regression (SLR) calibration methods indicated that apart from V (accuracy up to + 20%) the accuracy of analysis varies within 0.35-6.5% for SLR and 0.06-10% for PLS-R. A paired-sample t-test within the 95% confidence level yielded p-values greater than 0.05, meaning no appreciable statistical difference was observed between the univariate SLR with internal standardization and the multivariate PLS-R for most of the analytes. From the results obtained in this work, LIBS response varies depending on the element and the technique used for quantitative analysis. Simultaneous use of the univariate calibration curves with internal standard (intensity ratio) and PLS regression in multi-elemental analysis can help reduce the matrix effect of slags associated to their high variation in concentration. Overall, these results demonstrate the capability of LIBS as an alternative technique for analyzing gasification slags. Estimated limits of detection for Al, Ca, Fe, Si and V were 0.167, 0.78, 0.171, 0.243 and 0.01 wt.%, respectively.

  14. The Pediatric Choroidal and Ciliary Body Melanoma Study

    DEFF Research Database (Denmark)

    Al-Jamal, Rana'a T; Cassoux, Nathalie; Desjardins, Laurence;

    2016-01-01

    PURPOSE: To collect comprehensive data on choroidal and ciliary body melanoma (CCBM) in children and to validate hypotheses regarding pediatric CCBM: children younger than 18 years, males, and those without ciliary body involvement (CBI) have more favorable survival prognosis than young adults 18...

  15. Choroideremia associated with choroidal neovascularization treated with intravitreal bevacizumab

    Directory of Open Access Journals (Sweden)

    Palejwala NV

    2014-09-01

    Full Text Available Neal V Palejwala, Andreas K Lauer, Richard G Weleber Oregon Retinal Degeneration Center (ORDC, Ophthalmic Genetics Service and Retina-Vitreous Service, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA Purpose: To report a rare case of central vision loss in a patient with choroideremia.Patients and methods: A retrospective, interventional case report.Results: A 13-year-old male with history of choroideremia presented with subacute loss of central acuity in his left eye. Examination and diagnostic testing revealed subretinal fibrosis secondary to a choroidal neovascular membrane (CNVM. A trial of anti-vascular endothelial growth factor (VEGF therapy with the injection of intravitreal bevacizumab was attempted. Mild improvements in acuity and anatomy were noted.Conclusion: Choroideremia is a rare hereditary choroidal dystrophy that predominantly affects males in the first and second decades of life. Visual acuity is usually spared until later in life. CNVM is a rare manifestation of choroideremia with only a handful of case reports presented in the literature. This case is unique in that it is the first reported case that received treatment with intravitreal anti-VEGF therapy. Keywords: anti-VEGF therapy, choroideremia, choroidal neovascular membrane, chorioretinal degeneration, hereditary choroidal dystrophy, intravitreal bevacizumab injection

  16. Increased choroidal thickness in patient with high-altitude retinopathy

    Directory of Open Access Journals (Sweden)

    Kyoko Hirukawa-Nakayama

    2014-01-01

    Full Text Available We report a case of high-altitude retinopathy with increased choroidal thickness detected by spectral-domain optical coherence tomography (SD-OCT. A 36-year-old Japanese man developed an acute vision decrease in his left eye after he had trekked at an altitude of 4600 m in Tibet for 1 week. His visual acuity was 20/20 OD and 20/200 OS with refractive errors of − 0.25 diopters (D OD and − 0.50 D OS 3 weeks after the onset of the visual decrease. Funduscopic examinations revealed multiple intraretinal hemorrhages bilaterally and a macular hemorrhage in the left eye. SD-OCT showed that the thickness of choroidal layer at the fovea was 530 μm OD and 490 μm OS which is thicker than that in normal subjects of approximately 300 μm. We suggest that the increase in the retinal blood flow under hypoxic conditions may be associated with an increase in the choroidal blood flow resulting in an increase in choroidal thickness.

  17. Alleviating energy poverty: Indian experience

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Garima

    2010-09-15

    Energy services play an important role in human welfare. India faces acute energy poverty indicating lack of access of clean energy fuels. Access to electricity is limited to 56% households in India and about 89% of rural households depend on polluting energy sources. Energy poverty impacts income poverty as poor find it difficult to acquire high priced cleaner fuels. It also adversely impacts the socio economic conditions of women. The paper highlights the linkage of energy poverty with income poverty and gender inequality. It analyses measures taken to alleviate energy poverty and recommends regulatory and policy measures as way forward.

  18. Quantitative Remote Laser-Induced Breakdown Spectroscopy by Multivariate Analysis

    Science.gov (United States)

    Clegg, S. M.; Sklute, E. C.; Dyar, M. D.; Barefield, J. E.; Wiens, R. C.

    2007-12-01

    The ChemCam instrument selected for the Mars Science Laboratory (MSL) rover includes a remote Laser- Induced Breakdown Spectrometer (LIBS) that will quantitatively probe samples up to 9m from the rover mast. LIBS is fundamentally an elemental analysis technique. LIBS involves focusing a Nd:YAG laser operating at 1064 nm onto the surface of the sample. The laser ablates material from the surface, generating an expanding plasma containing electronically excited ions, atoms, and small molecules. As these electronically excited species relax back to the ground state, they emit light at wavelengths characteristic of the species present in the sample. Some of this emission is directed into one of three dispersive spectrometers. In this paper, we studied a suite of 18 igneous and highly-metamorphosed samples from a wide variety of parageneses for which chemical analyses by XRF were already available. Rocks were chosen to represent a range of chemical composition from basalt to rhyolite, thus providing significant variations in all of the major element contents (Si, Fe, Al, Ca, Na, K, O, Ti, Mg, and Mn). These samples were probed at a 9m standoff distance under experimental conditions that are similar to ChemCam. Extracting quantitative elemental concentrations from LIBS spectra is complicated by the chemical matrix effects. Conventional methods for obtaining quantitative chemical data from LIBS analyses are compared with new multivariate analysis (MVA) techniques that appear to compensate for these chemical matrix effects. The traditional analyses use specific elemental peak heights or areas, which compared with calibration curves for each element at one or more emission lines for a series of standard samples. Because of matrix effects, the calibration standards generally must have similar chemistries to the unknown samples, and thus this conventional approach imposes severe limitations on application of the technique to remote analyses. In this suite of samples, the use

  19. Laser-induced breakdown emission in hydrocarbon fuel mixtures

    Science.gov (United States)

    Kobayashi, Kazunobu; Bak, Moon Soo; Tanaka, Hiroki; Carter, Campbell; Do, Hyungrok

    2016-04-01

    Time-resolved emission measurements of laser-induced breakdown plasmas have been carried out to investigate the effect that gas species might have on the kinetics, particularly in excited states, and the resulting plasma properties. For this purpose, fuel-oxygen (O2)-carbon dioxide (CO2) mixtures with either helium (He) or nitrogen (N2) balance are prepared while maintaining their atomic compositions. The fuels tested in this study are methane (CH4), ethylene (C2H4), propane (C3H8), and butane (C4H10). The breakdown is produced in the mixtures (CH4/CO2/O2/He, C2H4/O2/He, C3H8/CO2/O2/He and C4H10/CO2/O2/He or CH4/CO2/O2/N2, C2H4/O2/N2, C3H8/CO2/O2/N2 and C4H10/CO2/O2/N2) at room conditions using the second harmonic of a Q-switched Nd:YAG laser (with pulse duration of 10 ns). The temporal evolution of plasma temperature is deduced from the ratio of two oxygen lines (777 nm and 823 nm) through Boltzmann analysis, while the evolution of electron number density is estimated based on Stark broadening of the Balmer-alpha (H α ) line at 656 nm and the measured plasma temperature. From the results, the temporal evolution of emission spectra and decay rates of atomic line-intensities are found to be almost identical between the breakdown plasma in the different mixtures given balancing gases. Furthermore, the temporal evolution of plasma temperature and electron number density are also found to be independent of the species compositions. Therefore, this behavior—of the breakdown emissions and plasma properties in the different mixtures with identical atomic composition—may be because the breakdown gases reach similar thermodynamic and physiochemical states immediately after the breakdown.

  20. Choroidal vascularity index as a measure of vascular status of the choroid: Measurements in healthy eyes from a population-based study

    Science.gov (United States)

    Agrawal, Rupesh; Gupta, Preeti; Tan, Kara-Anne; Cheung, Chui Ming Gemmy; Wong, Tien-Yin; Cheng, Ching-Yu

    2016-02-01

    The vascularity of the choroid has been implicated in the pathogenesis of various eye diseases. To date, no established quantifiable parameters to estimate vascular status of the choroid exists. Choroidal vascularity index (CVI) may potentially be used to assess vascular status of the choroid. We aimed to establish normative database for CVI and identify factors associated with CVI in healthy eyes. In this population-based study on 345 healthy eyes, choroidal enhanced depth imaging optical coherence tomography scans were segmented by modified image binarization technique. Total subfoveal choroidal area (TCA) was segmented into luminal (LA) and stromal (SA) area. CVI was calculated as the proportion of LA to TCA. Linear regression was used to identify ocular and systemic factors associated with CVI and subfoveal choroidal thickness (SFCT). Subfoveal CVI ranged from 60.07 to 71.27% with a mean value of 65.61 ± 2.33%. CVI was less variable than SFCT (coefficient of variation for CVI was 3.55 vs 40.30 for SFCT). Higher CVI was associated with thicker SFCT, but not associated with most physiological variables. CVI was elucidated as a significant determinant of SFCT. While SFCT was affected by many factors, CVI remained unaffected suggesting CVI to be a more robust marker of choroidal diseases.

  1. Choroidal thinning in high myopia measured by optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ikuno Y

    2013-05-01

    Full Text Available Yasushi Ikuno, Satoko Fujimoto, Yukari Jo, Tomoko Asai, Kohji NishidaDepartment of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, JapanPurpose: To investigate the rate of choroidal thinning in highly myopic eyes.Patients and methods: A retrospective observational study of 37 eyes of 26 subjects (nine males and 17 females, mean age 39.6 ± 7.7 years with high myopia but no pathologies who had undergone spectral domain optical coherence tomography and repeated the test 1 year later (1 ± 0.25 year at Osaka University Hospital, Osaka, Japan. Patients older than 50 years with visual acuity worse than 20/40 or with whitish chorioretinal atrophy involving the macula were excluded. Two masked raters measured the choroidal thicknesses (CTs at the foveda, 3 mm superiorly, inferiorly, temporally, and nasally on the images and averaged the values. The second examination was about 365 days after the baseline examination. The CT reduction per year (CTRPY was defined as (CT 1 year after - baseline CT/days between the two examinations × 365. The retinal thicknesses were also investigated.Results: The CTRPY at the fovea was −1.0 ± 22.0 µm (range –50.2 to 98.5 at the fovea, –6.5 ± 24.3 µm (range −65.8 to 90.2 temporally, –0.5 ± 22.3 µm (range –27.1 to 82.5 nasally, –9.7 ± 21.7 µm (range –40.1 to 60.1 superiorly, and –1.4 ± 25.5 µm (range –85.6 to 75.2 inferiorly. There were no significant differences in the CTRPY at each location (P = 0.34. The CT decreased significantly (P < 0.05 only superiorly. The superior CTRPY was negatively correlated with the axial length (P < 0.05. The retinal thickness at the fovea did not change. Stepwise analysis for CTRPY selected axial length (P = 0.04, R2 = 0.13 and age (P = 0.08, R2 = 0.21 as relevant factors.Conclusions: The highly myopic choroid might gradually thin and be affected by many factors. Location and axial length are key factors to regulate the rate of choroidal

  2. Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet

    Energy Technology Data Exchange (ETDEWEB)

    Mizukami, S., E-mail: mizukami@wpi-aimr.tohoku.ac.jp; Sugihara, A.; Suzuki, K. Z.; Miyazaki, T. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Iihama, S.; Sasaki, Y. [Department of Applied Physics, Tohoku University, Sendai 980-8579 (Japan)

    2016-01-04

    Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn{sub 3}Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant is approximately 60 Mrad/s and is comparable with those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.

  3. Photophysics of Laser Dye-Doped Polymer Membranes for Laser-Induced Fluorescence Photogrammetry

    Science.gov (United States)

    Dorrington, Adrian A.; Jones, Thomas W.; Danehy, Paul M.

    2004-01-01

    Laser-induced fluorescence target generation in dye-doped polymer films has recently been introduced as a promising alternative to more traditional photogrammetric targeting techniques for surface profiling of highly transparent or reflective membrane structures. We investigate the photophysics of these dye-doped polymers to help determine their long-term durability and suitability for laser-induced fluorescence photogrammetric targeting. These investigations included experimental analysis of the fluorescence emission pattern, spectral content, temporal lifetime, linearity, and half-life. Results are presented that reveal an emission pattern wider than normal Lambertian diffuse surface scatter, a fluorescence time constant of 6.6 ns, a pump saturation level of approximately 20 micro J/mm(exp 2), and a useful lifetime of more than 300,000 measurements. Furthermore, two demonstrations of photogrammetric measurements by laser-induced fluorescence targeting are presented, showing agreement between photogrammetric and physically measured dimensions within the measurement scatter of 100 micron.

  4. Laser-induced breakdown spectroscopy detection of heavy metal in water based on graphite conch method

    Science.gov (United States)

    Wang, Chunlong; Liu, Jianguo; Zhao, Nanjing; Shi, Huan; Liu, Lituo; Ma, Mingjun; Zhang, Wei; Chen, Dong; Liu, Jing; Zhang, Yujun; Liu, Wenqing

    2012-10-01

    The laser-induced breakdown spectroscopy emission characteristics of trace heavy metal lead in water is studied based on graphite conch method, with a 1064nm wavelength Nd: YAG laser as excitation source, the echelle spectrometer and ICCD detector are used for spectral separation and high sensitive detection with high resolution and wide spectral range. The delay time 900ns and gate time 1600ns are determined in the experiment. The calibration curve of Pb is plotted based on the different concentration measurement results, and a limit of detection of 0.0138mg / L is obtained for Pb in water. Graphite conch method effectively overcomes the current problems on laser-induced breakdown spectroscopy detection of heavy metal in water. The detection limits and stability are improved. The reference data is provided for further study on the fast measurement of trace heavy metals in water by laser induced breakdown spectroscopy technique.

  5. Quantitative measurement of electron number in nanosecond and picosecond laser-induced air breakdown

    Science.gov (United States)

    Wu, Yue; Sawyer, Jordan C.; Su, Liu; Zhang, Zhili

    2016-05-01

    Here we present quantitative measurements of total electron numbers in laser-induced air breakdown at pressures ranging from atmospheric to 40 barg by 10 ns and 100 ps laser pulses. A quantifiable definition for the laser-induced breakdown threshold is identified by a sharp increase in the measurable total electron numbers via dielectric-calibrated coherent microwave scattering. For the 10 ns laser pulse, the threshold of laser-induced breakdown in atmospheric air is defined as the total electron number of ˜106. This breakdown threshold decreases with an increase of pressure and laser photon energy (shorter wavelength), which is consistent with the theory of initial multiphoton ionization and subsequent avalanche processes. For the 100 ps laser pulse cases, a clear threshold is not present and only marginal pressure effects can be observed, which is due to the short pulse duration leading to stronger multiphoton ionization and minimal collisional avalanche ionization.

  6. Analysis of plutonium oxide surrogate residue using laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy was used to determine the elemental composition of a CeO2 composite powder for process control verification during lanthanide borosilicate glass fabrication. Cerium oxide is used as a surrogate for plutonium oxide, which along with other canister contents will be combined with frit to make glass. Laser-induced breakdown spectroscopy data for the composition of the CeO2 batch containing concentrations of Ce, Cr, Si, Fe, Ta, Ni, Zn, Al Mg, Gd, and W were quantitatively determined from laser-induced breakdown spectroscopy spectra of both pellet and powder samples. The results of both forms were compared and it was determined that the pellet data gave slightly better precision than the powder sample

  7. Real-time in vivo micromorphology and histopathology of choroidal osteoma using enhanced depth imaging

    Directory of Open Access Journals (Sweden)

    Rameez Hussain

    2015-01-01

    Full Text Available Choroidal osteoma is a usually unilateral benign tumor of the choroid composed of mature bone. Optical coherence tomography (OCT has been used to image osteoma for several years. With the advent of enhanced depth imaging (EDI feature of spectral-domain OCT (SD-OCT, better visualization of the morphology of choroidal lesions has been possible. Herein we present a case of choroidal osteoma in a 45-year-old woman, wherein in vivo morphology of the choroidal osteoma had been visualized using EDI technique of SD-OCT before and after performing photodynamic therapy. EDI OCT has proven to be a valuable noninvasive imaging modality, almost comparable to histopathological examination, for diagnosing choroidal osteomas and for providing an insight into the in vivo micromorphological changes occurring during the course of the disease.

  8. Comparisons of laser-saturated, laser-induced, and planar laser-induced fluorescence measurements of nitric oxide in a lean direct-injection spray flame.

    Science.gov (United States)

    Cooper, C S; Ravikrishna, R V; Laurendeau, N M

    1998-07-20

    We report quantitative, spatially resolved laser-saturated fluorescence (LSF), linear laser-induced fluorescence (LIF), and planar laser-induced fluorescence (PLIF) measurements of nitric oxide (NO) concentration in a preheated, lean direct-injection spray flame at atmospheric pressure. The spray is produced by a hollow-cone, pressure-atomized nozzle supplied with liquid heptane, and the overall equivalence ratio is unity. NO is excited by means of the Q(2)(26.5) transition of the gamma(0, 0) band. LSF and LIF detection are performed in a 2-nm region centered on the gamma(0, 1) band. PLIF detection is performed in a broad ~70-nm region with a peak transmission at 270 nm. Quantitative radial NO profiles obtained by LSF are presented and analyzed so as to correct similar LIF and PLIF profiles. Excellent agreement is achieved among the three fluorescence methodologies. PMID:18285943

  9. A study on reaction kinetics of the radicals produced in the laser-induced silane plasma

    International Nuclear Information System (INIS)

    The reaction kinetic processes of species produced in a pulsed TEA CO2 laser induced silane plasma were studied with the time-resolved OES. It is showed that the time position of main peaks for different fragments' characteristic lines are appreciably different. The reaction kinetic processes are discussed based on the results. By comparing the time evolution of the lines of the fragments and considering the other results of OES, the authors infer that the final reaction channel of the laser-induced silane plasma is a Si producing channel

  10. Boron- and iron-bearing molecules in laser-induced plasma

    International Nuclear Information System (INIS)

    Boron combines with alkali-earth elements, such as Ca, Mg, and Sr and with oxygen to form molecules in LIP of boron-bearing minerals with strong and characteristic band emission. It may be supposed that those bands are of CaBO2, MgBO2 and SrBO2 type. Besides, emission of BO, BO2 and FeO is also detected. - Highlights: • We studied laser-induced breakdown spectra of B with Ca, Mg and Sr in air. • Emission of polyatomic molecules was found. • Molecules of FeO were found in laser-induced plasma in air

  11. Benefits and applications of laser-induced sparks in real scale model measurements

    DEFF Research Database (Denmark)

    Gómez-Bolaños, Javier; Delikaris-Manias, Symeon; Pulkki, Ville Topias;

    2015-01-01

    The characteristics of using a laser-induced spark as a monopole source in scale model measurements were assessed by comparison with an electric spark and a miniature spherical loudspeaker. Room impulse responses of first order directivity sources were synthesized off-line using six spatially...... distributed sparks. The source steering direction was scanned across the horizontal and vertical plane to assess the origin of early reflections. The results confirm that the characteristics of the laser-induced spark outperform those of typical sources. Its monopole characteristics enable the authors...

  12. Evaluation of a laser-induced fluorescence system for uranium analysis

    International Nuclear Information System (INIS)

    A laser-induced fluorescence method for total uranium analysis of industrial process waters, waste waters, and leachates has been evaluated as a possible alternative for the normal, sodium fluoride and lithium fluoride, flame-fusion fluorescence method currently employed. Since the lower reporting limit of the laser fluorometer is on the order of 0.05 μg/L, samples for normal analysis can usually be diluted from 100 to 1000 fold which virtually eliminates interferences from quenching substances. Also, since the uranium determination is done in aqueous solution, laser-induced fluorescence entirely eliminates the need for organic extraction and the subsequent fusion process

  13. Laser-induced synthesis and decay of Tritium under exposure of solid targets in heavy water

    Science.gov (United States)

    Barmina, E. V.; Timashev, S. F.; Shafeev, G. A.

    2016-03-01

    The processes of laser-assisted synthesis of Tritium nuclei and their laser-induced decay in cold plasma in the vicinity of solid targets (Au, Ti, Se, etc.) immersed into heavy water are experimentally realized at peak laser intensity of 1010-1013 W/cm2. Initial stages of Tritium synthesis and their laser-induced beta-decay are interpreted on the basis of non-elastic interaction of plasma electrons having kinetic energy of 5-10 eV with nuclei of Deuterium and Tritium, respectively.

  14. Non-gated laser-induced breakdown spectroscopy in bulk water by position-selective detection

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Ye; Xue, Boyang; Song, Jiaojian; Lu, Yuan; Zheng, Ronger, E-mail: rzheng@ouc.edu.cn [Optics and Optoelectronics Laboratory, Ocean University of China, Qingdao 266100 (China)

    2015-09-14

    Temporal and spatial evolutions of the laser-induced plasma in bulk water are investigated using fast imaging and emission spectroscopic techniques. By tightly focusing a single-pulse nanosecond Nd: YAG laser beam into the bulk water, we generate a strongly expanded plasma with high reproducibility. Such a strong expanding plasma enables us to obtain well-resolved spectral lines by means of position-selective detection; hence, the time-gated detector becomes abdicable. The present results suggest not only a possible non-gated approach for underwater laser-induced breakdown spectroscopy but also give an insight into the plasma generation and expansion in bulk water.

  15. Boron- and iron-bearing molecules in laser-induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gaft, M.; Nagli, L.; Eliezer, N.; Groisman, Y.

    2015-08-01

    Boron combines with alkali-earth elements, such as Ca, Mg, and Sr and with oxygen to form molecules in LIP of boron-bearing minerals with strong and characteristic band emission. It may be supposed that those bands are of CaBO{sub 2}, MgBO{sub 2} and SrBO{sub 2} type. Besides, emission of BO, BO{sub 2} and FeO is also detected. - Highlights: • We studied laser-induced breakdown spectra of B with Ca, Mg and Sr in air. • Emission of polyatomic molecules was found. • Molecules of FeO were found in laser-induced plasma in air.

  16. Elemental analysis of halogens using molecular emission by laser-induced breakdown spectroscopy in air

    International Nuclear Information System (INIS)

    Fluorine and chlorine do not produce atomic and ionic line spectra of sufficient intensity to permit their detection by laser-induced breakdown spectroscopy. They do, however, combine with alkali-earths and other elements to form molecules whose spectra may be easily identified, enabling detection in ambient conditions with much higher sensitivity than using F I and Cl I atomic lines. - Highlights: • We studied laser induced breakdown spectra of halogens with alkali-earth elements. • Emission and temporal behavior of CaF and CaCl molecules were determined. • Sensitivity of F and Cl detection by molecules and atoms was compared

  17. Investigation of environmentally relevant colloids by laser-induced breakdown detection (LIBD)

    International Nuclear Information System (INIS)

    Full text of publication follows: An apparatus for laser-induced breakdown detection (LIBD) was established, which is aimed at in-situ detection of aquatic colloids of a particle size down to 2 atmosphere) by cathodic reduction of uranium(VI) followed by the successive increase of the pH by coulometric titration. The formation of these colloids was traced by LIBD. [1] Walther, C., Bitea, C., Hauser, W., Kim, J.I. and Scherbaum, F.J. Laser Induced Breakdown Detection for the Assessment of Colloid Mediated Radionuclide Migration. Nucl. Instr. and Meth. B 195 (2002) 374-388. (authors)

  18. Development and application of photofragmentation laser-induced fluorescence for visualization of hydrogen peroxides

    OpenAIRE

    Johansson, Olof

    2011-01-01

    The work presented in this thesis is mainly motivated by the need for an optical diagnostic technique which can be used to visualize hydrogen peroxide (H2O2) in its gas phase. Due to the lack of bound electronic states, H2O2 cannot be detected using laser-induced fluorescence based on electronic excitation. Absorption in the ultraviolet leads to photodissociation. Thus a technique called photofragmentation laser-induced fluorescence (PF-LIF) has been developed and applied. It is a pump-probe ...

  19. Comparison of calcium phosphate coatings formed on femtosecond laser-induced and sand-blasted titanium

    Science.gov (United States)

    Liang, C. Y.; Yang, X. J.; Wei, Q.; Cui, Z. D.

    2008-11-01

    High energy femtosecond laser process was employed to create regular surface patterning on titanium while sand blasting treatment made a coarse surface. Both laser-induced titanium and blasted titanium could promote the formation of calcium phosphate compounds after the acid and alkali treatment, but little crystallized hydroxyapatite was grown on the laser-induced titanium in 1.5SBF only for 6 h, whereas Ca 4P 6O 19 was formed on the sand-blasted titanium. The femtosecond laser process together with common acid and alkali treatment might provide potential choice to enhance the biocompatibility of titanium and its alloys.

  20. Elemental analysis of halogens using molecular emission by laser-induced breakdown spectroscopy in air

    Energy Technology Data Exchange (ETDEWEB)

    Gaft, M.; Nagli, L.; Eliezer, N.; Groisman, Y. [Laser Distance Spectrometry, 9 Mota Gur St., Petah Tikva 49514 (Israel); Forni, O. [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)

    2014-08-01

    Fluorine and chlorine do not produce atomic and ionic line spectra of sufficient intensity to permit their detection by laser-induced breakdown spectroscopy. They do, however, combine with alkali-earths and other elements to form molecules whose spectra may be easily identified, enabling detection in ambient conditions with much higher sensitivity than using F I and Cl I atomic lines. - Highlights: • We studied laser induced breakdown spectra of halogens with alkali-earth elements. • Emission and temporal behavior of CaF and CaCl molecules were determined. • Sensitivity of F and Cl detection by molecules and atoms was compared.

  1. Long-Term Cyclophosphamide Treatment in a Case with Serpiginous Choroiditis

    OpenAIRE

    Sahin, Ozlem G.

    2010-01-01

    Purpose To report the effect of long-term therapy with the alkylating agent cyclophosphamide in a case with serpiginous choroiditis and thus to contribute to the previously reported few cases showing the beneficial effect of long-term cyclophosphamide therapy for serpiginous choroiditis. Procedures Oral cyclophosphamide therapy for 12 months in a case with unilateral active serpiginous choroiditis. Results The active lesion responded well to long-term therapy with cyclophosphamide without rec...

  2. Primary Culture of Choroid Plexuses from Neonate Rats Containing Progenitor Cells Capable of Differentiation

    OpenAIRE

    Huang, Sheng-Li; He, Xi-jing; LI, ZONG-FANG; Yao, Lu; Yuan, Guo-Lian; Shi, Wei

    2013-01-01

    Background: The choroid plexuses, which could secrete a number of neurotrophins, have recently been used in transplantation in central nervous system diseases. Aims: To study the mechanism of nerve regeneration in the central nervous system by grafting choroid plexus tissues. Study Design: Animal experimentation. Methods: The choroid plexuses from the lateral ventricles of neonatal rats were cultured in adherent culture, and immunocytochemical methods were used t...

  3. Intravitreal Bevacizumab Injection Therapy in a Case with Choroidal Neovascular Membrane Secondary to Toxoplasmosis Retinochoroiditis

    OpenAIRE

    Sirel Gür Güngör; İmren Akkoyun; Evin Şingar; Gürsel Yılmaz

    2014-01-01

    A 57-year-old male patient presenting with visual loss in the left eye was diagnosed as choroidal neovascular membrane secondary to inactive toxoplasmosis retinochoroiditis scar. He underwent intravitreal bevacizumab injection as primary therapy. The choroidal neovascular membrane regressed partially and the initial visual acuity improved from 1/10 to 3/10. Intravitreal bevacizumab injection appears to be effective in the treatment of choroidal neovascular membrane secondary to toxop...

  4. Choroidal metastasis from early rectal cancer: Case report and literature review

    OpenAIRE

    Mitsuyoshi Tei; Masaki Wakasugi; Hiroki Akamatsu

    2014-01-01

    INTRODUCTION: Choroidal metastasis from colorectal cancer is rare, and there have been no reported cases of such metastasis from early colorectal cancer. We report a case of choroidal metastasis from early rectal cancer. PRESENTATION OF CASE: A 61 year-old-man experienced myodesopsia in the left eye 2 years and 6 months after primary rectal surgery for early cancer, and was diagnosed with left choroidal metastasis and multiple lung metastases. Radiotherapy was initiated for the left eye an...

  5. Current and emerging treatment options for myopic choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    El Matri L

    2015-04-01

    Full Text Available Leila El Matri, Ahmed Chebil, Fedra Kort Department B of Ophthalmology, Hedi Rais Institute of Ophthalmology, Faculty of Medicine of Tunis, University of El Manar, Tunis, Tunisia Abstract: Choroidal neovascularization (CNV is the main cause of visual impairment in highly myopic patients younger than 50 years of age. There are different treatments for myopic CNV (mCNV, with 5- to 10-year outcomes currently. Chorioretinal atrophy is still the most important determinant factor for visual outcome. The purpose of this study is to provide an overview of the current treatments for mCNV, including laser, surgical management, verteporfin photodynamic therapy, and mainly anti-vascular endothelial growth factor therapy. Emerging treatment options are also discussed. Keywords: myopia, choroidal neovascularization, current treatment, emerging treatment

  6. Cataract extraction after brachytherapy for malignant melanoma of the choroid

    International Nuclear Information System (INIS)

    Thirteen eyes of 55 consecutive patients treated with brachytherapy for malignant melanoma of the choroid developed postirradiation cataracts. Cataract development was more common in older patients and in patients with larger and more anterior tumors. Eleven eyes had extracapsular cataract extraction and intraocular lens implantation. Initial visual improvement occurred in 91% of eyes, with an average improvement of 5.5 lines. Visual acuity was maintained at 20/60 or better in 55% of the eyes over an average period of follow-up of 24 months (range, 6 to 40 months). These data suggest that, visually, cataract extraction can be helpful in selected patients who develop a cataract after brachytherapy for malignant melanoma of the choroid

  7. [Histopathologic study of melanoma of the choroid after proton therapy].

    Science.gov (United States)

    Devouassoux Shishe Boran, M; Grange, J D; Patricot, L M; Adeleine, P; Chauvel, P; Chiquet, C; Vitrey, D; Thivolet Béjui, F

    1997-07-01

    To evaluate irradiation effects on choroidal melanomas, histopathologic findings of 18 eyes whose primary treatment was enucleation were compared to 15 eyes enucleated after proton beam irradiation. Irradiated tumors showed more likely necrosis (p = 0.01) had balloon cells (p = 0.01), and inflammatory infiltrate (p = 0.05). In the irradiated group, the prevalence of tumor blood vessel damage was higher (p = 0.0002) and mitotic figures were fewer (p = 0.01). These findings suggest that proton beam irradiation damages tumor cells and alters the tumor's capacity for cellular reproduction. It damages blood vessels leading to tumor necrosis. It induces an inflammatory response of unknown effects. Radiosensitivity of choroidal melanomas cannot be assessed using conventional histologic methods. However, tumor necrosis, mitotic activity and rate of balloon cells can help to establish tumoral sensitivity to irradiation. PMID:9296578

  8. Cataract extraction after brachytherapy for malignant melanoma of the choroid

    Energy Technology Data Exchange (ETDEWEB)

    Fish, G.E.; Jost, B.F.; Snyder, W.I.; Fuller, D.G.; Birch, D.G. (Texas Retina Associates, Dallas (USA))

    1991-05-01

    Thirteen eyes of 55 consecutive patients treated with brachytherapy for malignant melanoma of the choroid developed postirradiation cataracts. Cataract development was more common in older patients and in patients with larger and more anterior tumors. Eleven eyes had extracapsular cataract extraction and intraocular lens implantation. Initial visual improvement occurred in 91% of eyes, with an average improvement of 5.5 lines. Visual acuity was maintained at 20/60 or better in 55% of the eyes over an average period of follow-up of 24 months (range, 6 to 40 months). These data suggest that, visually, cataract extraction can be helpful in selected patients who develop a cataract after brachytherapy for malignant melanoma of the choroid.

  9. Proliferation of Cultured Mouse Choroid Plexus Epithelial Cells

    OpenAIRE

    Barkho, Basam Z.; Monuki, Edwin S.

    2015-01-01

    The choroid plexus (ChP) epithelium is a multifunctional tissue found in the ventricles of the brain. The major function of the ChP epithelium is to produce cerebrospinal fluid (CSF) that bathes and nourishes the central nervous system (CNS). In addition to the CSF, ChP epithelial cells (CPECs) produce and secrete numerous neurotrophic factors that support brain homeostasis, such as adult hippocampal neurogenesis. Accordingly, damage and dysfunction to CPECs are thought to accelerate and inte...

  10. Choroidal Coloboma in a Case of Tay-Sachs Disease

    OpenAIRE

    Nasreen Raees Ahmed; Koushik Tripathy; Vivek Kumar; Varun Gogia

    2014-01-01

    Coloboma as an ocular finding has been documented in various syndromes. Here we have a case of infantile Tay-Sachs disease associated with unilateral choroidal coloboma. To the best of our knowledge, such an association has not been documented in the literature. Whether such an association is a matter of chance or signifies the involvement of ganglioside metabolism in ocular embryogenesis remains to be elucidated.

  11. Choroidal Coloboma in a Case of Tay-Sachs Disease

    Directory of Open Access Journals (Sweden)

    Nasreen Raees Ahmed

    2014-01-01

    Full Text Available Coloboma as an ocular finding has been documented in various syndromes. Here we have a case of infantile Tay-Sachs disease associated with unilateral choroidal coloboma. To the best of our knowledge, such an association has not been documented in the literature. Whether such an association is a matter of chance or signifies the involvement of ganglioside metabolism in ocular embryogenesis remains to be elucidated.

  12. Choroidal coloboma in a case of tay-sachs disease.

    Science.gov (United States)

    Ahmed, Nasreen Raees; Tripathy, Koushik; Kumar, Vivek; Gogia, Varun

    2014-01-01

    Coloboma as an ocular finding has been documented in various syndromes. Here we have a case of infantile Tay-Sachs disease associated with unilateral choroidal coloboma. To the best of our knowledge, such an association has not been documented in the literature. Whether such an association is a matter of chance or signifies the involvement of ganglioside metabolism in ocular embryogenesis remains to be elucidated. PMID:25295204

  13. Application of Intravitreal Bevacizumab for Circumscribed Choroidal Hemangioma

    OpenAIRE

    Sagong, Min; Lee, Junyeop; Chang, Woohyok

    2009-01-01

    We report 3 cases of circumscribed choroidal hemangioma (CCH) effectively managed with intravitreal bevacizumab. One patient (case 1) who had recurrent CCH (1.6 mm in thickness) with prior laser photocoagulation was treated with intravitreal bevacizumab alone. Two patients (case 2 and 3) who had CCH (2.4 mm and 2.2 mm in thickness, respectively) with recent visual impairment were treated with bevacizumab followed by photodynamic therapy (PDT). Ophthalmic evaluations included visual acuity, op...

  14. Systemic bevacizumab for simultaneous treatment of cancer and choroidal neovascularisation

    OpenAIRE

    Saffra, Norman; Reinherz, Benjamin

    2014-01-01

    A 47-year-old woman with a medical history of pseudoxanthoma elasticum and associated choroidal neovascularisation that was successfully managed with intravitreal bevacizumab injections developed non-squamous non-small cell lung carcinoma. The patient's oncological medication regimen included systemic bevacizumab. During the 22 months that the patient received systemic bevacizumab for management of her malignancy, intravitreal bevacizumab injections were held and the patient's visual acuity r...

  15. Current and emerging treatment options for myopic choroidal neovascularization

    OpenAIRE

    El Matri L.; Chebil A; Kort F

    2015-01-01

    Leila El Matri, Ahmed Chebil, Fedra Kort Department B of Ophthalmology, Hedi Rais Institute of Ophthalmology, Faculty of Medicine of Tunis, University of El Manar, Tunis, Tunisia Abstract: Choroidal neovascularization (CNV) is the main cause of visual impairment in highly myopic patients younger than 50 years of age. There are different treatments for myopic CNV (mCNV), with 5- to 10-year outcomes currently. Chorioretinal atrophy is still the most important determinant factor for visua...

  16. Current and emerging treatment options for myopic choroidal neovascularization

    OpenAIRE

    El Matri, Leila

    2015-01-01

    Leila El Matri, Ahmed Chebil, Fedra Kort Department B of Ophthalmology, Hedi Rais Institute of Ophthalmology, Faculty of Medicine of Tunis, University of El Manar, Tunis, Tunisia Abstract: Choroidal neovascularization (CNV) is the main cause of visual impairment in highly myopic patients younger than 50 years of age. There are different treatments for myopic CNV (mCNV), with 5- to 10-year outcomes currently. Chorioretinal atrophy is still the most important determinant factor for v...

  17. Myopic choroidal neovascularisation: current concepts and update on clinical management

    OpenAIRE

    Wong, Tien Y.; Ohno-Matsui, Kyoko; Leveziel, Nicolas; Holz, Frank G.; Lai, Timothy Y; Yu, Hyeong Gon; Lanzetta, Paolo; Chen, Youxin; Tufail, Adnan

    2014-01-01

    Choroidal neovascularisation (CNV) is a common vision-threatening complication of myopia and pathological myopia. Despite significant advances in understanding the epidemiology, pathogenesis and natural history of myopic CNV, there is no standard definition of myopic CNV and its relationship to axial length and other myopic degenerative changes. Several treatments are available to ophthalmologists, but with the advent of new therapies there is a need for further consensus and clinical managem...

  18. Choroidal neovascularisation in pathological myopia: an update in management

    OpenAIRE

    Chan, W-M; Ohji, M; Lai, T Y Y; Liu, D T L; Tano, Y.; Lam, D S C

    2005-01-01

    Choroidal neovascularisation (CNV) secondary to pathological myopia is an important cause of significant visual impairment in young and middle aged adults globally and is particularly prevalent in Asian populations. In the past few years, there have been rapid advancements in the different treatments for myopic CNV. The purpose of this perspective is to give an overview of the natural history of myopic CNV and the various treatment options including laser photocoagulation, photodynamic therap...

  19. MGMT promoter methylation and temozolomide response in choroid plexus carcinoma

    OpenAIRE

    Misaki, Kouichi; NAKADA, Mitsutoshi; Mohri, Masanao; Hayashi, Yutaka; Hamada, Jun-ichiro

    2011-01-01

    Choroid plexus carcinoma (CPC) is a malignant tumor with a strong tendency to spread along the cerebrospinal fluid pathway. There is no standardized chemotherapy protocol for this rare tumor. We report a 38-year-old man with CPC in the lateral ventricle with obstructive hydrocephalus. Because of the poor demarcation between thalamus and fornix, subtotal tumor resection was performed. Postoperative spine magnetic resonance (MR) image revealed whole spinal axis dissemination. After diagnosis of...

  20. Early detection of choroidal neovascularization in age related macular degeneration

    OpenAIRE

    Tural Galbinur

    2014-01-01

    Purpose: to identify factors associated with early detection of choroidal neovascularization CNV in clinical practice.Methods: Seventy six AMD patients who had history of CNV in one eye and presented with CNV in the second eye and evaluated for association with visual acuity (VA) at time of presentation. Demographics, clinical data and lesion characteristics were retrospectively collected.Results: Better VA was associated with history of CNV in the fellow eye (p<0.0001), adherence to follo...

  1. Choroid plexus metastasis of renal-cell carcinoma

    International Nuclear Information System (INIS)

    A rare case of the choroid plexus metastasis of renal-cell carcinoma is reported. A 58-year-old man was admitted on March 3, 1982, with complaints of mild headache and a transient attack of muscle weakness of the left upper extremity. He had undergone a left nephrectomy because of renal-cell carcinoma 2 years before this admission. A CT scan revealed a small mass in the right lateral ventricle that was markedly enhanced by the contrast medium. A carotid angiogram was normal, but a left vertebral angiogram showed a round tumor stain in the distal portion of the right posterior choroidal artery. To determine the nature of the tumor, it was successfully removed via the right frontal transventricular approach. The immediate recovery from the operation was uneventful, but the patient became semicomatose 6 hours later because of a large subdural hematoma over the left hemisphere. An emergency operation for clot removal and external decompression failed to improve the patient's status, and he died on the 3rd postoperative day. An histological examination of the tumor determined the diagnosis of clear-cell-type renal-cell carcinoma. The CT demonstration of choroid plexus metastasis is quite rare. To our knowledge, only two cases have been described. (author)

  2. Choroid plexus calcification: clinical, neuroimaging and histopathological correlations in schizophrenia.

    Science.gov (United States)

    Marinescu, Ileana; Udriştoiu, I; Marinescu, D

    2013-01-01

    Schizophrenia is recognized as a psychiatric disorder that causes the most pronounced disturbances of cognition and social integration. In the etiopathogenesis of the disease, genetic, neurobiological and vascular factors are involved. Functional integrity of the brain can be correlated with the integrity of the blood-brain barrier (BBB), and the dysfunction of this barrier is an indicator that suggests neurodevelopmental abnormalities, injuries of various etiologies and dysfunctions within the small vessels of the brain that disrupt the calcium homeostasis. Neuroimaging shows that in patients with poor evolution, cognitive dysfunction and therapeutic resistance, the presence of choroid plexus calcification associated with hippocampal, frontal, temporoparietal and cerebellar atrophies. Antipsychotics with high capacity to block D2 dopamine receptors (haloperidol model) can aggravate apoptotic mechanisms of the brain areas involved in cognition and disrupts the functional integrity of the BBB due to decreased of choroid plexus blood flow because of the narrowing of cerebral small vessels. Choroid plexus calcification may be a predictive indicator of poor evolution or of a neurodegenerative type. PMID:23771083

  3. Harnessing motivation to alleviate neglect

    Directory of Open Access Journals (Sweden)

    Charlotte eRussell

    2013-06-01

    Full Text Available The syndrome of spatial neglect results from the combination of a number of deficits in attention, with patients demonstrating both spatially lateralised and non-lateralised impairments. Previous reports have hinted that there may be a motivational component to neglect and that modulating this might alleviate some of the debilitating symptoms. Additionally, recent work on the effects of reward on attention in healthy participants has revealed improvements across a number of paradigms. As the primary deficit in neglect has been associated with attention, this evidence for reward’s effects is potentially important. However, until very recently there have been few empirical studies addressing this potential therapeutic avenue. Here we review the growing body of evidence that attentional impairments in neglect can be reduced by motivation, for example in the form of preferred music or anticipated monetary reward, and discuss the implications of this for treatments for these patients. Crucially these effects of positive motivation are not observed in all patients with neglect, suggesting that the consequences of motivation may relate to individual lesion anatomy. Given the key role of dopaminergic systems in motivational processes, we suggest that motivational stimulation might act as a surrogate for dopaminergic stimulation. In addition, we consider the relationship between clinical post stroke apathy and lack of response to motivation.

  4. Effect of surrounding gases and water vapor on the induced electric current associated with a laser-induced plasma

    Science.gov (United States)

    Matsuta, Hideyuki

    2016-04-01

    The effect of surrounding gases and water vapor on the laser-induced electric current was investigated. Laser-induced plasma was generated on an aluminum alloy target. The laser-induced plasma was optically examined to estimate the excitation temperature and electron density in room air. There was a linear relationship between the maximum amplitude of the laser-induced current and the electron density. As the electron mean free path of the surrounding gas increased, the observed amplitude of the current increased. The amplitude of the induced current signal in dry air became maximum upon mixing with the optimum amount of water vapor. This enhancement of the induced current signal might be due to the large relative permittivity of water vapor. The laser-induced plasma as a whole seems to be a low-temperature plasma consisting of electrons, a large amount of cold surrounding gas, injected hot atoms, hot ions, and hot particles.

  5. Equine infectious anemia viral vector-mediated codelivery of endostatin and angiostatin driven by retinal pigmented epithelium-specific VMD2 promoter inhibits choroidal neovascularization.

    Science.gov (United States)

    Kachi, Shu; Binley, Katie; Yokoi, Katsutoshi; Umeda, Naoyasu; Akiyama, Hideo; Muramatu, Daisuke; Iqball, Sharifah; Kan, On; Naylor, Stuart; Campochiaro, Peter A

    2009-01-01

    Equine infectious anemia virus (EIAV) is a nonprimate lentivirus that does not cause human disease. Subretinal injection into mice of a recombinant EIAV lentiviral vector in which lacZ is driven by a CMV promoter (EIAV CMV LacZ) resulted in rapid and strong expression of LacZ in retinal pigmented epithelial (RPE) cells and some other cells including ganglion cells, resulting in the presence of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside within the optic nerve. Substitution of the RPE-specific promoter from the vitelliform macular dystrophy (VMD2) gene for the CMV promoter resulted in prolonged (at least 1 year) expression of LacZ that was restricted to RPE cells, albeit reduced 6- to 10-fold compared with the CMV promoter. Similarly, the amount of FLAG-tagged endostatin detected in eyes injected with the EIAV VMD2 Endo(FLAG) vector was similar to that seen in eyes injected with a vector that expressed both endostatin and angiostatin [EIAV VMD2 Endo(FLAG)/Angio]; expression was approximately 6-fold lower than with identical vectors in which the CMV promoter drove expression. Compared with murine eyes treated with a control EIAV vector, subretinal injection of EIAV vectors expressing murine endostatin alone or in combination with angiostatin driven by either the CMV or VMD2 promoter caused significant suppression of choroidal neovascularization (NV) at laser-induced rupture sites in Bruch's membrane. These data support proceeding toward clinical studies with EIAV-based gene therapy for choroidal NV, using the VMD2 promoter to selectively drive expression of a combination of endostatin and angiostatin in RPE cells. PMID:20377369

  6. Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy

    NARCIS (Netherlands)

    Sovago, M.; Buis, E.-J.; Sandtke, M.

    2013-01-01

    We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP

  7. Two-temperature model for pulsed-laser-induced subsurface modifications in Si

    NARCIS (Netherlands)

    Verburg, P.C.; Römer, G.R.B.E.; Huis In 'T Veld, A.J.

    2014-01-01

    We investigated the laser-material interaction during the production of laser-induced subsurface modifications in silicon with a numerical model. Such modifications are of interest for subsurface wafer dicing. To predict the shape of these modifications, a two-temperature model and an optical model

  8. Research on laser weld penetration monitoring with laser induced plasma signals

    Institute of Scientific and Technical Information of China (English)

    段爱琴; 胡伦骥; 王亚军

    2004-01-01

    In this paper, laser induced plasma signals were analyzed during keyhole welding through three methods. According to the results, the relativity between optical and acoustic signals of plasma is shown when welds are in full-penetration, or partial-penetration and non-penetration.

  9. Speciation of actinides in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

    International Nuclear Information System (INIS)

    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) as a sensitive and selective method has been applied to the speciation of actinides in aqueous solution. Studies on hydrolysis and carbonate complexation of U(VI) and on determination of hydration number of Cm(III) are reported. (author)

  10. Serum Protein Profile Study of Clinical Samples Using High Performance Liquid Chromatography-Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Karemore, Gopal Raghunath; Ukendt, Sujatha; Rai, Lavanya;

    2009-01-01

    The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested for...

  11. Determination of irradiation parameters for laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Römer, G.R.B.E.; Huis in 't Veld, A.J.

    2013-01-01

    The spatial emergence of laser-induced periodic surface structures (LIPSS) on single-crystalline silicon, upon irradiation with linearly polarized picosecond laser pulses (wavelength λ = 1030 nm, pulse duration τ = 6.7 ps, pulse repetition frequency fp = 1 kHz) was studied theoretically and experime

  12. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, Ole; Nedela, T; Urbassek, H; Schou, J

    2002-01-01

     The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  13. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, O.; Nedelea, T.; Schou, Jørgen; Urbassek, H.M.

    The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  14. Application of Ansys Program in Laser-induced Interstitial Thermotherapy (LITT)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influence of heat source by laser irradiating on tissue temperature was simulated with the Ansys program, and the distribution of tissue temperature under the heat source was shown. Compared with others, the simulation method with ansys program is more intuitionistic and can offer very good reference for Laser- induced interstitial thernotherapy.

  15. Boosting persistence time of laser-induced plasma by electric arc discharge for optical emission spectroscopy

    International Nuclear Information System (INIS)

    Plasma induced by nanosecond laser ablation is re-excited by a pulsed electric discharge and the parameters and optical emission of the plasma are measured. The discharge is a low-voltage and high-current electric arc that is triggered by the laser-induced plasma and slowly decaying with time. The optical emission of such combined plasma lasts up to several milliseconds which is much longer than without re-excitation (μs range). The emission spectra of re-excited plasma measured on different sample materials show higher line intensities than spectra measured by conventional laser-induced breakdown spectroscopy (LIBS). Moreover, emission lines of fluorine (spectral range 683–691 nm) and sulfur (range 520–550 nm) not detected by conventional LIBS become easily detectable with the combined plasma. The concentration of major components in metallurgical slags, as determined by calibration-free LIBS, agrees very well to the reference data evaluating the spectra taken from re-excited plasma. - Highlights: • Persistence time of laser-induced plasma in air is increased from ~ 10 μs to ~ 1 ms. • Laser-induced plasma triggers an electric arc discharge that boosts the plasma. • The combined laser-arc plasma is in LTE state over very long time (ms range). • CF-LIBS method delivers accurate results evaluating spectra of combined plasma. • Emission from S and F, not detected by LIBS, is detected with combined plasma

  16. Verification of a characterization method of the laser-induced selective activation based on industrial lasers

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Tang, Peter T.;

    2013-01-01

    In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser-machine...

  17. The spatial emergence of laser-induced periodic surface structures under lateral displacement irradiation conditions

    NARCIS (Netherlands)

    Eichstädt, Justus

    2015-01-01

    Recently, laser-induced periodic surface structures, abbreviated LIPSS, gained interest, because potential applications are seen in the field of surface functionalisation. The feasibility to produce LIPSS and the potential to influence surface functionality have been shown. But so far, the implement

  18. IR Laser-Induced Synthesis of Nanostructured Gemanium Telluride in the Gas Phase

    Czech Academy of Sciences Publication Activity Database

    Pola, Josef; Pokorná, Dana; Diánez, M.J.; Sayagués, M.J.; Bastl, Zdeněk; Vorlíček, Vladimír

    2005-01-01

    Roč. 19, č. 7 (2005), s. 854-858. ISSN 0268-2605 R&D Projects: GA AV ČR(CZ) IAA4072107 Institutional research plan: CEZ:AV0Z40720504 Keywords : laser-induced decomposition * germanium telluride * pyrolysis Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.190, year: 2005

  19. Formation of nitric oxide in an industrial burner measured by 2-D laser induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A.; Bombach, R.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    We have performed two-dimensional Laser Induced Fluorescence (2-D LIF) measurements of nitric oxide and hydroxyl radical distributions in an industrial burner at atmospheric pressure. The relative 2-D LIF data of NO were set to an absolute scale by calibration with probe sampling combined with gas analysis. (author) 3 figs., 7 refs.

  20. The spatial resolution of the porcine multifocal electroretinogram for detection of laser-induced retinal lesions

    DEFF Research Database (Denmark)

    Kyhn, Maria Voss; Kiilgaard, Jens Folke; Scherfig, Erik;

    2008-01-01

    This study aimed to investigate the spatial resolution of a porcine multifocal electroretinogram (mfERG) protocol by testing its ability to detect laser-induced retinal lesions. Furthermore, we wanted to describe time-dependent changes in implicit time and amplitude of the different mfERG peaks...

  1. Laser induced pressure pulse probe of charge distribution in thermally poled glass: Evidence of dipole polarisation?

    OpenAIRE

    Kazansky, P G; Smith, A. R.; Russell, P. St. J.; Yang, G.M.; Sessler, G.M.

    1995-01-01

    For the first time charge distributions in thermally poled silica glass are mapped by using laser induced pressure pulse technique. The experimental results may be explained through postulating the formation of both real space charge layers and inside the the depletion region

  2. Laser induced fluorescence measurements of the mixing of fuel oil with air

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A.; Bombach, R.; Hubschmid, W.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    We report on measurements of the mixing of fuel oil with air at atmospheric pressure in an industrial premixed gas turbine burner. The concentration of the vaporized fuel oil was measured with laser induced fluorescence. We reason that the fuel oil concentration can be considered with good accuracy as proportional to the fluorescence intensity. (author) 6 fig., 3 refs.

  3. A review of the development of portable laser induced breakdown spectroscopy and its applications

    Czech Academy of Sciences Publication Activity Database

    Rakovský, Jozef; Čermák, P.; Musset, O.; Veis, P.

    2014-01-01

    Roč. 101, NOV 2014 (2014), s. 269-287. ISSN 0584-8547 R&D Projects: GA ČR GA13-11635S Institutional support: RVO:61388955 Keywords : Fiber laser * Fieldable LIBS * Laser-induced breakdown spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.176, year: 2014

  4. What can we learn about laser-induced plasmas from Thomson scattering experiments

    International Nuclear Information System (INIS)

    This article describes laser Thomson scattering as applied to investigate laser-induced plasmas originating from gas breakdown or ablation of solid samples. Thomson scattering provides a reliable and direct mean of determining plasma electron density and electron temperature with high spatial and temporal resolution. Moreover, unlike e.g. optical emission spectroscopy, no assumptions about axial symmetry, thermodynamic conditions in the plasma or its chemical composition are needed to quantify these fundamental plasma parameters. Because Thomson scattering is inherently accompanied by Rayleigh light scattering, information about concentration of heavy particles and their temperature can be simultaneously derived from the experimental data. The heavy particle temperature and the electron one are the primary indicators of the plasma thermodynamic equilibrium. The goals of this article are to describe the theory of Thomson scattering relevant for the studies of low-temperature laser-induced plasmas, discuss the instrumental details of Thomson scattering experiments, and review the results of studies in which this technique has been used to characterize laser-induced plasmas. - Highlights: • Thomson scattering in diagnostics of breakdown in gases and ablative plasmas • Description of the theory of Thomson scattering relevant for low-temperature laser plasmas • Discussion on the instrumental details of Thomson scattering experiments • Review of studies in which TS was used to characterize laser-induced plasmas

  5. Capillary Electrophoretic Immunoassay with Laser-induced Fluorescence Detection for Interferon-gamma

    Institute of Scientific and Technical Information of China (English)

    Hua ZHANG; Hai Ming WEI; Wen Rui JIN

    2004-01-01

    Capillary electrophoretic immunoassay with laser-induced fluorescence detection for recombinant human interferon-gamma (IFN-γ) was established. The limits of detection for three forms of IFN-γare 6.9 ng/L, 5.7 ng/L and 5.0 ng/L, respectively.

  6. [The Spectral Analysis of Laser-Induced Plasma in Laser Welding with Various Protecting Conditions].

    Science.gov (United States)

    Du, Xiao; Yang, Li-jun; Liu, Tong; Jiao, Jiao; Wang, Hui-chao

    2016-01-01

    The shielding gas plays an important role in the laser welding process and the variation of the protecting conditions has an obvious effect on the welding quality. This paper studied the influence of the change of protecting conditions on the parameters of laser-induced plasma such as electron temperature and electron density during the laser welding process by designing some experiments of reducing the shielding gas flow rate step by step and simulating the adverse conditions possibly occurring in the actual Nd : YAG laser welding process. The laser-induced plasma was detected by a fiber spectrometer to get the spectral data. So the electron temperature of laser-induced plasma was calculated by using the method of relative spectral intensity and the electron density by the Stark Broadening. The results indicated that the variation of protecting conditions had an important effect on the electron temperature and the electron density in the laser welding. When the protecting conditions were changed, the average electron temperature and the average electron density of the laser-induced plasma would change, so did their fluctuation range. When the weld was in a good protecting condition, the electron temperature, the electron density and their fluctuation were all low. Otherwise, the values would be high. These characteristics would have contribution to monitoring the process of laser welding. PMID:27228732

  7. Recurrence and massive extraocular extension of choroidal malignant melanoma after vitrectomy and endoresection

    Directory of Open Access Journals (Sweden)

    Mehdi Modarres

    2014-01-01

    Full Text Available Vitrectomy and endoresection is an alternative to enucleation for the treatment of large malignant choroidal melanoma. We report a rare case of extensive recurrence of choroidal malignant melanoma with extraocular extension 11 years after surgical endoresection without adjuvant treatment.

  8. Magnetic resonance imaging in a dog with a choroid plexus carcinoma

    International Nuclear Information System (INIS)

    Magnetic resonance imaging was used ante mortem to confirm the anatomic location of an intracranial lesion in a dog with neurological signs. Necropsy revealed the lesion to be a choroid plexus carcinoma with thalamic invasion. A review of the literature on choroid plexus carcinomas in the dog is included

  9. Suprasellar seeding of a benign choroid plexus papilloma of the fourth ventricle with local recurrence

    Energy Technology Data Exchange (ETDEWEB)

    Irsutti, M.; Thorn-Kany, M.; Arrue, P.; Manelfe, C. [Service de Neuro-Radiologie Diagnostique et Interventionnelle, Centre Hospitalier Universitaire Purpan, Toulouse (France); Richaud, J.; Sol, J.C. [Service de Neurochirurgie, Centre Hospitalier Universitaire Rangueil, Toulouse (France); Delisle, M.B. [Laboratoire d' Anatomie et de Cytologie Pathologiques, Centre Hospitalier Universitaire Rangueil, Toulouse (France)

    2000-09-01

    A suprasellar location of a benign choroid plexus papilloma is reported. Local recurrence within the fourth ventricle was also present, 8 years after apparently complete removal. Imaging and histological findings were similar to those of the initial lesion. At surgery, the suprasellar lesion had no connection with the ventricular system. Seeding of choroid plexus papillomas is discussed, and the pertinent literature reviewed. (orig.)

  10. Shaggy Photoreceptors with Subfoveal Fluid Associated with a Distant Choroidal Melanoma

    Directory of Open Access Journals (Sweden)

    Ann Q. Tran

    2015-01-01

    Full Text Available Purpose. To describe the enhanced depth imaging optical coherence tomography (EDI-OCT findings in a patient with an extra macula choroidal melanoma before and after treatment. Methods. Observational case report. Results. A 45 year-old Caucasian male patient was referred to retina clinic for management of choroidal melanoma. Examination revealed a nasal choroidal melanoma while EDI-OCT illustrated subfoveal fluid pocket with elongated shaggy photoreceptors distant and separate from the tumor. The patient was treated with plaque brachytherapy and intravitreal bevacizumab. One week after plaque removal, there was a dramatic reduction in the shaggy photoreceptors. Conclusion. Choroidal melanomas have effects that are not localized to the area of the tumor. This loculated pocket of subretinal fluid and coinciding changes to photoreceptor morphology may be related to global changes in choroidal function or release of tumor related cytokines.

  11. Effect of vascular endothelial growth factor inhibitors on choroid in patients with macular choroid neovascular membrane and degenerative myopia . Preliminary report

    Directory of Open Access Journals (Sweden)

    V. A. Solomin

    2014-07-01

    Full Text Available Purpose: to assess the effect of vascular endothelial growth factor inhibitors on choroid in patients with myopic macular choroid neovascular membrane.Methods: 12 eyes (12 patients aged 19-47 years with myopia and macular choroid neovascular membrane (mCNV were enrolled in a study group. A control group included fellow eyes with early «dry» form age-related macular degeneration. Eyes with mCNV under- went one intravitreal injection of vascular endothelial growth factor inhibitor Ranibizumab 0.5 mg. Retina and choroid examination was performed with SPECtRALIS HRA+OCt (Heidelberg Engineering. Eyes were examined before treatment, in 1 month and in 3 months after treatment.Results: Mean best corrected visual acuity in 1 moth after ranibizumab 0.5 mg injection improved from 0.37±0.18 to 0.47±0.24. In 3 months after treatment best corrected visual acuity was 0.53±0.24. Mean foveal retinal thickness before treatment was 311.4±57.2 μm; 1 month and 3 months after treatment mean foveal retinal thickness decreased to 229.1±41.8 μm and 221.8±29.3 μm, respec- tively. Mean choroid thickness in 1 moth decreased from 54.4±23.7 μm to 37.4±17.0 μm, in 3 moths mean choroid thickness was 48.9±20.1 μm. In the control group best corrected visual acuity was 0.79±0.18, mean foveal retinal thickness and mean choroid thick- ness were 187.1±10.5 μm and 93.7±24.5 μm, respectively.Conclusion: Injection of vascular endothelial growth factor inhibitor allowed transient choroid thinning.

  12. Three-dimensional choroidal segmentation in spectral OCT volumes using optic disc prior information

    Science.gov (United States)

    Hu, Zhihong; Girkin, Christopher A.; Hariri, Amirhossein; Sadda, SriniVas R.

    2016-03-01

    Recently, much attention has been focused on determining the role of the peripapillary choroid - the layer between the outer retinal pigment epithelium (RPE)/Bruchs membrane (BM) and choroid-sclera (C-S) junction, whether primary or secondary in the pathogenesis of glaucoma. However, the automated choroidal segmentation in spectral-domain optical coherence tomography (SD-OCT) images of optic nerve head (ONH) has not been reported probably due to the fact that the presence of the BM opening (BMO, corresponding to the optic disc) can deflect the choroidal segmentation from its correct position. The purpose of this study is to develop a 3D graph-based approach to identify the 3D choroidal layer in ONH-centered SD-OCT images using the BMO prior information. More specifically, an initial 3D choroidal segmentation was first performed using the 3D graph search algorithm. Note that varying surface interaction constraints based on the choroidal morphological model were applied. To assist the choroidal segmentation, two other surfaces of internal limiting membrane and innerouter segment junction were also segmented. Based on the segmented layer between the RPE/BM and C-S junction, a 2D projection map was created. The BMO in the projection map was detected by a 2D graph search. The pre-defined BMO information was then incorporated into the surface interaction constraints of the 3D graph search to obtain more accurate choroidal segmentation. Twenty SD-OCT images from 20 healthy subjects were used. The mean differences of the choroidal borders between the algorithm and manual segmentation were at a sub-voxel level, indicating a high level segmentation accuracy.

  13. Choroidal Blood-Flow Responses to Hyperoxia and Hypercapnia in Men with Obstructive Sleep Apnea

    Science.gov (United States)

    Tonini, Matthieu; Khayi, Hafid; Pepin, Jean-Louis; Renard, Elisabeth; Baguet, Jean-Philippe; Lévy, Patrick; Romanet, Jean-Paul; Geiser, Martial H.; Chiquet, Christophe

    2010-01-01

    Study Objectives: Obstructive sleep apnea (OSA) impacts on macrovasculature and autonomic function and may therefore interfere with ocular microvascular regulation. We hypothesized that choroidal vascular reactivity to hyperoxia and hypercapnia was altered in patients with OSA compared with matched control subjects and would improve after treatment with continuous positive airway pressure (CPAP). Methods: Sixteen healthy men were matched 1:1 for body mass index, sex, and age with 16 men with newly diagnosed OSA without comorbidities. Subjects underwent sleep studies, 24-hour blood pressure monitoring, arterial stiffness measurements, and cardiac and carotid echography. Overall, patients were middle-aged, lean, and otherwise healthy except for having OSA with a limited amount of desaturation, with, at most, subclinical lesions of the cardiovascular system, stage 1 hypertension, or both. Choroidal laser Doppler flowmetry provides a unique opportunity to assess microvascular function by measuring velocity, (ChBVel), volume (ChBVol), and relative subfoveal choroidal blood flow (ChBF). Vascular choroidal reactivity was studied during hyperoxia and hypercapnia (8% CO2) challenges before and after treatment with nasal CPAP. Results: Patients with OSA and control subjects exhibited similar choroidal reactivity during hyperoxia (stability of choroidal blood flow) and hypercapnia (significant increases in ChBVel of 13.5% and in ChBF of 16%). Choroidal vasoreactivity to CO2 was positively associated with arterial stiffness in patients with OSA. Gas choroidal vasoreactivity was unchanged after 6 to 9 months of CPAP treatment. Conclusion: This study showed unimpaired choroidal vascular reactivity in otherwise healthy men with OSA. This suggests that patients with OSA, without comorbidities, have long-term adaptive mechanisms active in ocular microcirculation. Citation: Tonini M; Khayi H; Pepin JL; Renard E; Baguet JP; Lévy P; Romanet JP; Geiser MH; Chiquet C. Choroidal blood

  14. The choroid plexus response to a repeated peripheral inflammatory stimulus

    Directory of Open Access Journals (Sweden)

    Palha Joana A

    2009-11-01

    Full Text Available Abstract Background Chronic systemic inflammation triggers alterations in the central nervous system that may relate to the underlying inflammatory component reported in neurodegenerative disorders such as multiple sclerosis and Alzheimer's disease. However, it is far from being understood whether and how peripheral inflammation contributes to induce brain inflammatory response in such illnesses. As part of the barriers that separate the blood from the brain, the choroid plexus conveys inflammatory immune signals into the brain, largely through alterations in the composition of the cerebrospinal fluid. Results In the present study we investigated the mouse choroid plexus gene expression profile, using microarray analyses, in response to a repeated inflammatory stimulus induced by the intraperitoneal administration of lipopolysaccharide every two weeks for a period of three months; mice were sacrificed 3 and 15 days after the last lipopolysaccharide injection. The data show that the choroid plexus displays a sustained response to the repeated inflammatory stimuli by altering the expression profile of several genes. From a total of 24,000 probes, 369 are up-regulated and 167 are down-regulated 3 days after the last lipopolysaccharide injection, while at 15 days the number decreases to 98 and 128, respectively. The pathways displaying the most significant changes include those facilitating entry of cells into the cerebrospinal fluid, and those participating in the innate immune response to infection. Conclusion These observations contribute to a better understanding of the brain response to peripheral inflammation and pave the way to study their impact on the progression of several disorders of the central nervous system in which inflammation is known to be implicated.

  15. Choriocapillaris and choroidal microvasculature imaging with ultrahigh speed OCT angiography.

    Directory of Open Access Journals (Sweden)

    WooJhon Choi

    Full Text Available We demonstrate in vivo choriocapillaris and choroidal microvasculature imaging in normal human subjects using optical coherence tomography (OCT. An ultrahigh speed swept source OCT prototype at 1060 nm wavelengths with a 400 kHz A-scan rate is developed for three-dimensional ultrahigh speed imaging of the posterior eye. OCT angiography is used to image three-dimensional vascular structure without the need for exogenous fluorophores by detecting erythrocyte motion contrast between OCT intensity cross-sectional images acquired rapidly and repeatedly from the same location on the retina. En face OCT angiograms of the choriocapillaris and choroidal vasculature are visualized by acquiring cross-sectional OCT angiograms volumetrically via raster scanning and segmenting the three-dimensional angiographic data at multiple depths below the retinal pigment epithelium (RPE. Fine microvasculature of the choriocapillaris, as well as tightly packed networks of feeding arterioles and draining venules, can be visualized at different en face depths. Panoramic ultra-wide field stitched OCT angiograms of the choriocapillaris spanning ∼32 mm on the retina show distinct vascular structures at different fundus locations. Isolated smaller fields at the central fovea and ∼6 mm nasal to the fovea at the depths of the choriocapillaris and Sattler's layer show vasculature structures consistent with established architectural morphology from histological and electron micrograph corrosion casting studies. Choriocapillaris imaging was performed in eight healthy volunteers with OCT angiograms successfully acquired from all subjects. These results demonstrate the feasibility of ultrahigh speed OCT for in vivo dye-free choriocapillaris and choroidal vasculature imaging, in addition to conventional structural imaging.

  16. The formation of rats' choroidal neovascularization induced by acrolein

    OpenAIRE

    Guan-Feng Wang; Xiu-Lan Zou; Dong-Hao Li; Chen Wang; Wen-Li Li; Rong-Biao Pi

    2016-01-01

    AIM:To investigate the formation of rats' choroidal neovascularization(CNV)induced by acrolein. METHODS:Twelve Sprague-Dawley rats were randomly divided into three groups. Acrolein 200μL(2.5 mg/kg/d)was poured into the rats' stomach for 4wk as acrolein 4wk and for 8wk as acrolein 8wk group. The same volume of fresh water was also done to the rats as the control group. Remove all eye balls and embed into paraffin with HE staining.RESLUTS:The RPE-Bruch membrane was intact with no obvious abnorm...

  17. A CASE OF GYRATE ATROPHY OF THE CHOROID & RETINA

    Directory of Open Access Journals (Sweden)

    Satyavathi

    2015-01-01

    Full Text Available Gyrate atrophy of the choroid and retina is a rare chorioretinal degeneration inherited by on autosonal recessive mode of transmission. It is caused by mutation in gene for ornithine aminotransferase (OAT, located on chromosome 10. It is characterised by high myopia with astigmatism, night blindness during 2 nd and 3 rd decade with a slowly progressive posterior sub capsular cataract. Once diagnosed paediatrician/physician and Ophthalmologist should be aware of the follow up. No single therapy has been shown to halt the progression of the disease.

  18. In vivo Analysis of Choroid Plexus Morphogenesis in Zebrafish

    OpenAIRE

    Marta García-Lecea; Igor Kondrychyn; Fong, Steven H.; Zhang-Rui Ye; Vladimir Korzh

    2008-01-01

    BACKGROUND: The choroid plexus (ChP), a component of the blood-brain barrier (BBB), produces the cerebrospinal fluid (CSF) and as a result plays a role in (i) protecting and nurturing the brain as well as (ii) in coordinating neuronal migration during neurodevelopment. Until now ChP development was not analyzed in living vertebrates due to technical problems. METHODOLOGY/PRINCIPAL FINDINGS: We have analyzed the formation of the fourth ventricle ChP of zebrafish in the GFP-tagged enhancer trap...

  19. Study of the blood-aqueous barrier in choroidal melanoma.

    OpenAIRE

    Castella, A P; Bercher, L; Zografos, L; Egger, E.; Herbort, C P

    1995-01-01

    AIMS--Aqueous flare was used to determine the frequency and amount of blood-aqueous barrier breakdown and correlate it with tumour variables. METHODS--Aqueous flare was analysed prospectively by laser flare photometry in 139 consecutive patients seen in the oncology unit for choroidal melanoma. Both eyes of patients were examined with a laser flare cell meter in a standard fashion. RESULTS--Mean flare difference between healthy and tumour eyes was 3.01 (SD 2.5) photons per millisecond (ph/ms)...

  20. Current and emerging treatment options for myopic choroidal neovascularization.

    Science.gov (United States)

    El Matri, Leila; Chebil, Ahmed; Kort, Fedra

    2015-01-01

    Choroidal neovascularization (CNV) is the main cause of visual impairment in highly myopic patients younger than 50 years of age. There are different treatments for myopic CNV (mCNV), with 5- to 10-year outcomes currently. Chorioretinal atrophy is still the most important determinant factor for visual outcome. The purpose of this study is to provide an overview of the current treatments for mCNV, including laser, surgical management, verteporfin photodynamic therapy, and mainly anti-vascular endothelial growth factor therapy. Emerging treatment options are also discussed. PMID:25987831

  1. Inkjet Printing of Viscous Monodisperse Microdroplets by Laser-Induced Flow Focusing

    Science.gov (United States)

    Delrot, Paul; Modestino, Miguel A.; Gallaire, François; Psaltis, Demetri; Moser, Christophe

    2016-08-01

    The on-demand generation of viscous microdroplets to print functional or biological materials remains challenging using conventional inkjet-printing methods, mainly due to aggregation and clogging issues. In an effort to overcome these limitations, we implement a jetting method to print viscous microdroplets by laser-induced shockwaves. We experimentally investigate the dependence of the jetting regimes and the droplet size on the laser-pulse energy and on the inks' physical properties. The range of printable liquids with our device is significantly extended compared to conventional inkjet printers's performances. In addition, the laser-induced flow-focusing phenomenon allows us to controllably generate viscous microdroplets up to 210 mPa s with a diameter smaller than the nozzle from which they originated (200 μ m ). Inks containing proteins are printed without altering their functional properties, thus demonstrating that this jetting technique is potentially suitable for bioprinting.

  2. Measurements of egg shell plasma parameters using laser-induced breakdown spectroscopy

    Indian Academy of Sciences (India)

    Wenfeng Luo; Xiaoxia Zhao; Shuyuan Lv; Haiyan Zhu

    2015-07-01

    Measurements of 1064 nm laser-induced egg shell plasma parameters are presented in this paper. Of special interests were its elemental identification and the determination of spectroscopic temperature and electron density. The electron temperature of 5956 K was inferred using an improved iterative Boltzmann plot method with six calcium atomic emission lines, and the electron number density of 6.1 × 1016 cm−3 was determined by measuring the width of Stark-broadened once-ionized calcium line at 393.37 nm. Based on the experimental results, the laser-induced egg shell plasma was verified to be optically thin and satisfy local thermodynamic equilibrium (LTE). Furthermore, experiments also demonstrated that the loss of energy due to the reflection of the laser beam from the plasma can be neglected and the inverse bremsstrahlung (IB) absorption was the dominant mechanism of plasma heating at the IR wavelength.

  3. Simulating fluorescence light-canopy interaction in support of laser-induced fluorescence measurements

    International Nuclear Information System (INIS)

    In the Netherlands an operational field instrument for the measurement of laser induced fluorescence of vegetation (LEAF) is developed. In addition, plant physiological and remote sensing research is done to support this new remote sensing instrument. This paper presents a general introduction on the subject of laser-induced fluorescence, including the relation between chlorophyll fluorescence and photosynthesis, spectral characteristics, and previous research. Also the LEAF system is briefly described. Subsequently, the development of a leaf fluorescence model (KMF) and a canopy fluorescence model (FLSAIL) are reported. With these simulation models a sensitivity study is carried out. Fluorescence of 685 nm appears to be most suitable to obtain information on photosynthesis and stress, but is also influenced by canopy structure. Separation of these two effects is studied

  4. Mechanisms of two-color laser-induced field-free molecular orientation.

    Science.gov (United States)

    Spanner, Michael; Patchkovskii, Serguei; Frumker, Eugene; Corkum, Paul

    2012-09-14

    Two mechanisms of two-color (ω+2ω) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g., on the order of ≳0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanisms lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally. PMID:23005623

  5. Identification of inks and structural characterization of contemporary artistic prints by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Identification of the inks used in artistic prints and the order in which different ink layers have been applied on a paper substrate are important factors to complement the classical stylistic aspects for the authentication of this type of objects. Laser-induced breakdown spectroscopy (LIBS) is investigated to determine the chemical composition and structural distribution of the constituent materials of model prints made by applying one or two layers of several blue and black inks on an Arches paper substrate. By using suitable laser excitation conditions, identification of the inks was possible by virtue of emissions from key elements present in their composition. Analysis of successive spectra on the same spot allowed the identification of the order in which the inks were applied on the paper. The results show the potential of laser-induced breakdown spectroscopy for the chemical and structural characterization of artistic prints

  6. Some properties of atomic beam produced by laser induced ablation of Li target

    International Nuclear Information System (INIS)

    Pulsed atomic beams produced in vacuum by laser induced ablation from a lithium target are analyzed by laser induced fluorescence (LIF). The 1-mixing processes induced in the n = 9, 10 Li Rydberg states by collisions with CO2 molecules illustrate the application of the method. Resolution is limited by the 1 mm diameter of the probe laser beam. Combining LIF and absorption measurements gives nLi as a function of time at various distances from the target surface. The investigation of the Li-C02 1-mixing process in a heat pipe oven proved impossible due to the high reactivity of Li with C02. This problem was solved by renewing the Li atoms at each laser shot. Values obtained for n = 9, n = 10 are k = 17 x 10-8 and 15 x 10-8 cc/sec, respectively

  7. Note: A novel technique for analysis of aqueous solutions by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rusak, D. A.; Bell, Z. T. [Department of Chemistry, University of Scranton, Scranton, Pennsylvania 18510 (United States); Anthony, T. P. [Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)

    2015-11-15

    Surface-enhanced Raman spectroscopy (SERS) substrates typically consist of gold or silver nanoparticles deposited on a non-conductive substrate. In Raman spectroscopy, the nanoparticles produce an enhancement of the electromagnetic field which, in turn, leads to greater electronic excitation of molecules in the local environment. Here, we show that these same surfaces can be used to enhance the signal-to-noise ratio obtained in laser-induced breakdown spectroscopy of aqueous solutions. In this case, the SERS substrates not only lower breakdown thresholds and lead to more efficient plasma initiation but also provide an appropriately wettable surface for the deposition of the liquid. We refer to this technique as surface-enhanced laser-induced breakdown spectroscopy.

  8. Investigations for the correction of presbyopia by fs-laser-induced cuts

    Science.gov (United States)

    Ripken, Tammo; Oberheide, Uwe; Heisterkamp, Alexander; Ertmer, Wolfgang; Gerten, Georg; Lubatschowski, Holger

    2004-07-01

    The most probable reason for presbyopia is an age-related loss of the elasticity of the lens. It develops through the whole life, but is first noticeable typically at the age of about 45. From that on it leads within 15 years to a total loss of the accommodation ability. However, both, the ciliary muscle and the lens capsule stay active and elastic, respectively. With respect to this, a possible treatment conception is to increase or regain the elasticity. The possibility to increase elasticity with ps-laser induced cuts inside the lens was already shown by Krueger. We made an improvement in cutting quality while using a fs laser with 5~kHz repetition rate emitting in the near infrared. Different fs-laser-induced μm smooth cuts inside fresh enucleated ex-vivo pig lenses will be presented.

  9. Experimental investigation on dynamic characteristics and strengthening mechanism of laser-induced cavitation bubbles.

    Science.gov (United States)

    Ren, X D; He, H; Tong, Y Q; Ren, Y P; Yuan, S Q; Liu, R; Zuo, C Y; Wu, K; Sui, S; Wang, D S

    2016-09-01

    The dynamic features of nanosecond laser-induced cavitation bubbles near the light alloy boundary were investigated with the high-speed photography. The shock-waves and the dynamic characteristics of the cavitation bubbles generated by the laser were detected using the hydrophone. The dynamic features and strengthening mechanism of cavitation bubbles were studied. The strengthening mechanisms of cavitation bubble were discussed when the relative distance parameter γ was within the range of 0.5-2.5. It showed that the strengthening mechanisms caused by liquid jet or shock-waves depended on γ much. The research results provided a new strengthening method based on laser-induced cavitation shotless peening (CSP). PMID:27150764

  10. Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule

    International Nuclear Information System (INIS)

    Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm2, a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

  11. Hyperspectral laser-induced flourescence imaging for assessing internal quality of kiwi fruit

    Science.gov (United States)

    Liu, Muhua; Liao, Yifeng; Zhou, Xiaomei

    2008-03-01

    This paper describes an experimental study on non-destructive methods for predicting quality of kiwifruits using fluorescence imaging. The method is based on hyperspectral laser-induced fluorescence imaging in the region between 700 and 1110 nm, and estimates the kiwifruits quality in terms of internal sugar content and firmness. A station for acquiring hyperspectral laser-induced fluorescence imaging has been designed and carefully choosing each component. The fluorescence imaging acquired by the station has been pre-processed by selecting regions of interest (ROIs) of 50 100 × pixels. A line regressing prediction method estimates the quality of kiwifruit samples. The results obtained in classification show that the station and prediction model enables the correct discrimination of kiwifruits internal sugar content and firmness with a percentage of r= 98.5%, SEP=0.4 and r=99.9%, SEP=0.62.

  12. Ultraviolet femtosecond and nanosecond laser ablation of silicon: Ablation efficiency and laser-induced plasma expansion

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Xianzhong; Mao, Xianglei; Greif, Ralph; Russo, Richard E.

    2004-03-23

    Femtosecond laser ablation of silicon in air was studied and compared with nanosecond laser ablation at ultraviolet wavelength (266 nm). Laser ablation efficiency was studied by measuring crater depth as a function of pulse number. For the same number of laser pulses, the fs-ablated crater was about two times deeper than the ns-crater. The temperature and electron number density of the pulsed laser-induced plasma were determined from spectroscopic measurements. The electron number density and temperature of fs-pulse plasmas decreased faster than ns-pulse plasmas due to different energy deposition mechanisms. Images of the laser-induced plasma were obtained with femtosecond time-resolved laser shadowgraph imaging. Plasma expansion in both the perpendicular and the lateral directions to the laser beam were compared for femtosecond and nanosecond laser ablation.

  13. Spectral analysis of Qinling Mountain rock using laser induced breakdown spectroscopy

    Science.gov (United States)

    Luo, W. F.; Zhao, X. X.; Zhu, H. Y.; Xie, D. H.; Liu, J.; Jin, P. F.

    2013-12-01

    The composition of Qinling Mountain rock is studied using laser induced breakdown spectroscopy for the first time. Elements Ca, Mg, Cu, Fe, C, Na, Si, Al, Ti, K and Mn are identified qualitatively. Using an improved iterative Boltzmann plot method, the electron temperature of 16,825 K is inferred with Ca I lines at 422.67, 428.30, 443.49, 445.48, and 585.74 nm, while the ionic temperature of 15,587 K is obtained with Ca II lines at 393.37, 396.85, and 370.60 nm. The electron number density of 1.49 ? 10? cm? is inferred from the Stark broadened profile of Ca I 422.67 nm averaged with 10 single spectra. The laser-induced rock plasma is verified to be in local thermodynamic equilibrium and to be optically thin based on the experimental results.

  14. On two optomechanical effects of laser-induced electrostriction in dielectric liquids

    CERN Document Server

    Gojani, Ardian B; Obayashi, Shigeru

    2014-01-01

    This paper presents electrostriction from the phenomenological perspective, and gives details on two mechanical effects arising from laser-matter interaction. Electrostriction is the tendency of materials to compress in the presence of a varying electric field. In this paper, the investigated materials are polar and nonpolar dielectric liquids. It is stressed that the dominant factor is the time evolution of the laser pulse, which causes tensile stresses and acoustic waves. The study is supported by experimental realization of electrostriction, which can be detected only at favourable conditions (observed in water, but not in castor oil). This study will shed light in developing measurement techniques (e.g., laser-induced grating spectroscopy) and in explaining the onset of cavities and laser-induced liquid breakdown.

  15. Mechanisms of two-color laser-induced field-free molecular orientation

    CERN Document Server

    Spanner, Michael; Frumker, Eugene; Corkum, Paul

    2012-01-01

    Two mechanisms of two-color (\\omega + 2\\omega) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g. on the order of || > 0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanism lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally.

  16. Simultaneous laser induced breakdown spectroscopy and Pd-assisted methane decomposition at different pressures

    International Nuclear Information System (INIS)

    Methane decomposition is investigated during Pd-assisted laser induced plasma in the controlled chamber at various pressures using Q-switched Nd:YAG laser. Real time LIBS monitoring is applied to reveal the involved mechanisms during methane decomposition by inspecting the plasma parameters at mano-metric pressures of 1 to 10 mbar. The dependence of electron density and plasma temperature with pressure is also studied. It is shown that the plasma recreates higher hydrocarbons during the decomposition of methane. In addition, Fourier transform infrared spectroscopy, gas chromatography, scanning electron microscopy and transmission electron microscopy are applied to support the findings. - Highlights: ► Simultaneous laser induced breakdown spectroscopy ► Pd-assisted methane decomposition ► Nanosecond pulsed laser decomposition of methane ► Generation of higher hydrocarbon ► Dependence of electron density and temperature of induced plasma with pressure

  17. Laser-induced plasma spectroscopy of hydrogen Balmer series in laboratory air.

    Science.gov (United States)

    Swafford, Lauren D; Parigger, Christian G

    2014-01-01

    Stark-broadened emission profiles for the hydrogen alpha and beta Balmer series lines in plasma are measured to characterize electron density and temperature. Plasma is generated using a typical laser-induced breakdown spectroscopy (LIBS) arrangement that employs a focused Q-switched neodymium-doped yttrium aluminum garnet (Nd : YAG) laser, operating at the fundamental wavelength of 1064 nm. The temporal evolution of the hydrogen Balmer series lines is explored using LIBS. Spectra from the plasma are measured following laser-induced optical breakdown in laboratory air. The electron density is primarily inferred from the Stark-broadened experimental data collected at various time delays. Due to the presence of nitrogen and oxygen in air, the hydrogen alpha and beta lines become clearly discernible from background radiation for time delays of 0.4 and 1.4 μs, respectively. PMID:25226255

  18. Identification of inks and structural characterization of contemporary artistic prints by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oujja, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Vila, A. [Departament de Pintura, Conservacio-Restauracio, Facultat de Belles Arts, Universitat de Barcelona, Pau Gargallo 4, 08028 Barcelona (Spain); Rebollar, E. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Garcia, J.F. [Departament de Pintura, Conservacio-Restauracio, Facultat de Belles Arts, Universitat de Barcelona, Pau Gargallo 4, 08028 Barcelona (Spain); Castillejo, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain)]. E-mail: marta.castillejo@iqfr.csic.es

    2005-08-31

    Identification of the inks used in artistic prints and the order in which different ink layers have been applied on a paper substrate are important factors to complement the classical stylistic aspects for the authentication of this type of objects. Laser-induced breakdown spectroscopy (LIBS) is investigated to determine the chemical composition and structural distribution of the constituent materials of model prints made by applying one or two layers of several blue and black inks on an Arches paper substrate. By using suitable laser excitation conditions, identification of the inks was possible by virtue of emissions from key elements present in their composition. Analysis of successive spectra on the same spot allowed the identification of the order in which the inks were applied on the paper. The results show the potential of laser-induced breakdown spectroscopy for the chemical and structural characterization of artistic prints.

  19. Laser-induced damage behaviors of antireflective coatings at cryogenic condition.

    Science.gov (United States)

    Wang, He; Zhang, Weili; He, Hongbo

    2012-12-20

    The laser-induced damage to antireflective coatings on Yb:YAG crystals under different temperatures was investigated. An optical profiler, field-emission scanning-electron microscopy, and a step profiler were used to determine the damage morphology, including size and depth. The results show that there is about 5 J/cm(2) decrease in the laser-induced damage threshold of cryogenic conditions compared to that of room temperature in 1-on-1 test mode, and a 3 J/cm(2) decrease in 100-on-1 mode. There is an accumulation effect in both cases. Meanwhile, the damage areas and depths are also much larger under cryogenic conditions. The precipitation of the subsurface defects in the substrate and the thermal stress in the interface between the film and the substrate under cryogenic conditions are considered to be the key factors in the unique damage behaviors. PMID:23262610

  20. Laser-induced condensation by ultrashort laser pulses at 248 nm

    OpenAIRE

    Joly, P; Petrarca, M.; Vogel, A.(Physikalisches Institut, University of Bonn, Bonn, Germany); Pohl, T; Nagy, T.; Jusforgues, Q.; Simon, P.; Kasparian, J.; Weber, K.; Wolf, J.-P.

    2013-01-01

    We compare laser-induced condensation by UV laser pulses of femtosecond, sub-picosecond, and nanosecond duration between each other, as well as with respect to near-infrared (NIR) (800 nm) ultrashort laser pulses. Particle nucleation by UV pulses is so efficient that their growth beyond several hundreds of nm is limited by the local concentration of water vapour molecules. Furthermore, we evidence a dual mechanism: While condensation induced by ultrashort UV pulses rely on nitrogen photo-oxid...

  1. Successful treatment of laser induced hypopigmentation with narrowband ultraviolet B targeted phototherapy

    Directory of Open Access Journals (Sweden)

    Venkataram Mysore

    2013-01-01

    Full Text Available Q-switched 1064 nm neodymium-doped yttrium aluminium garnet (Qs 1064 nm Nd: YAG laser plays an important role in the treatment of pigmentary skin disorders, including tattoos. Although it has high efficacy and safety, adverse effect like hypopigmentation may occur causing anxiety to patients. We present a case report of Qs 1064 nm Nd: YAG laser induced hypopigmentation which was successfully treated with ultraviolet B targeted phototherapy, with rapid and satisfactory re-pigmentation.

  2. Laser-induced breakdown spectroscopy based detection of lunar soil simulants for moon exploration

    Institute of Scientific and Technical Information of China (English)

    Rong Shu; Hongxing Qi; Gang Lü; Demin Ma; Zhiping He; Yongqi Xue

    2007-01-01

    A scientific goal of the moon exploration project is to perform elemental analysis on the moon surface.The assuming of using laser-induced breakdown spectroscopy (LIBS) for this goal has been put forward.The laser plasma used by LIBS is sensitive to the surrounding atmosphere and the moon has very low ambient gas pressure on the surface, so the study of the LIBS capabilities at the low pressure was carried out.

  3. Laser-induced forward transfer of liquids: Study of the droplet ejection process

    OpenAIRE

    Colina, M.; Duocastella, M.; Fernández Pradas, Juan Marcos; Serra Coromina, Pere; Morenza Gil, José Luis

    2006-01-01

    Laser-induced forward transfer (LIFT) is a laser direct-write technique that offers the possibility of printing patterns with a high spatial resolution from a wide range of materials in a solid or liquid state, such as conductors, dielectrics, and biomolecules in solution. This versatility has made LIFT a very promising alternative to lithography-based processes for the rapid prototyping of biomolecule microarrays. Here, we study the transfer process through the LIFT of droplets of a solution...

  4. Laser-induced forward transfer of liquids : Study of the droplet ejection process

    OpenAIRE

    Colina Brito, Mónica Alejandra; Duocastella, Martí; Fernández Pradas, J. Marcos; Serra Coromina, Pere; Morenza, José L.

    2006-01-01

    Laser-induced forward transfer LIFT is a laser direct-write technique that offers the possibility of printing patterns with a high spatial resolution from a wide range of materials in a solid or liquid state, such as conductors, dielectrics, and biomolecules in solution. This versatility has made LIFT a very promising alternative to lithography-based processes for the rapid prototyping of biomolecule microarrays. Here, we study the transfer process through the LIFT of droplets of a solut...

  5. On the formation mechanism of laser-induced plasma in high-power laser welding

    International Nuclear Information System (INIS)

    The formation mechanism of laser-induced plasma and the mechanism of the laser energy loss caused by plasma in high-power laser welding are investigated theoretically and experimentally. The results show that the plasma generation is determined by the power density of impinging laser beam and the laser energy loss caused by plasma is mainly manifested in the form of absorption and scattering, with the magnitude of loss depending on the wavelength of the impinging laser beam

  6. X-ray photoemission investigation of excimer laser induced etching of InP

    International Nuclear Information System (INIS)

    ArF excimer laser induced etching of InP in various etch gases (HBr, HCl, Cl2) is discussed with regard to its spatial resolution capability. X-ray photoemission spectra and large-area etch rate measurements published before lead to fundamental understanding and interpretation of the characteristics of etched test structures. HBr and HCl require gas phase photodissociation. Cl2, in contrast, has the advantage to react spontaneously

  7. Laser-induced isotopic selectivity in the resonance ionization of Os

    OpenAIRE

    Wunderlich, R. K.; Hutcheon, I. D.; Wasserburg, G. J.; Blake, G. A.

    1992-01-01

    Isotope selective effects in resonance ionization mass spectrometry (RIMS) pose a potentially serious limitation to the application of this technique to the precise and reproducible measurement of isotope ratios. In order to identify some of the underlying causes of isotope selectivity in RIMS and to establish procedures for minimizing these effects, we investigated laser-induced isotope selectivity in the resonance ionization of Os. A single-color, one-photon resonant ionization scheme was u...

  8. Model-based planning and real-time predictive control for laser-induced thermal therapy

    OpenAIRE

    Feng, Yusheng; Fuentes, David

    2011-01-01

    In this article, the major idea and mathematical aspects of model-based planning and real-time predictive control for laser-induced thermal therapy (LITT) are presented. In particular, a computational framework and its major components developed by authors in recent years are reviewed. The framework provides the backbone for not only treatment planning but also real-time surgical monitoring and control with a focus on MR thermometry enabled predictive control and applications to image-guided ...

  9. Time-resolved laser-induced fluorescence in the nuclear fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Moulin, C.; Decambox, P.; Mauchien, P.; Petit, A. [CEA Centre d`Etudes de saclay, 91 - Gif-sur-Yvette (France). Lab. de Spectroscopie Laser Analytique

    1995-03-01

    Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented. (author).

  10. Time-resolved laser-induced fluorescence in the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented. (author)

  11. Detection and Classification of Live and Dead Escherichia coli by Laser-Induced Breakdown Spectroscopy

    OpenAIRE

    P. Sivakumar; Fernández-Bravo, A.; Taleh, L.; J. F. Biddle; Melikechi, N.

    2015-01-01

    A common goal for astrobiology is to detect organic materials that may indicate the presence of life. However, organic materials alone may not be representative of currently living systems. Thus, it would be valuable to have a method with which to determine the health of living materials. Here, we present progress toward this goal by reporting on the application of laser-induced breakdown spectroscopy (LIBS) to study characteristics of live and dead cells using Escherichia coli (E. coli) stra...

  12. Identification of British one pound counterfeit coins using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Appleby, Andrew; Thevar, Thangavel

    2016-04-01

    The use of laser-induced breakdown spectroscopy (LIBS) as a low-cost, nondestructive method for detecting counterfeit coins was examined. A pulsed laser was used to evaporate a minute amount of coin surface, and the emanating plasma was interrogated with an entry-level spectrometer. The spectra produced showed evidence of lead content in six of the eight counterfeits examined. Thus, LIBS could offer a viable low-cost technique for identifying a significant number of fake coins.

  13. Laser-Induced Continuum Structure of NO Molecules in Two-Colour Femtosecond Pulsed Laser Fields

    Institute of Scientific and Technical Information of China (English)

    WANG Sen-Ming; YUAN Kai-Jun; CONG Shu-Lin

    2006-01-01

    The method of quantum wave packet dynamics is used to study the multiphoton ionization of NO molecules via a two-photon Raman coupling and a laser-induced continuum structure (LICS) state in two-colour strong femtosecond pulsed laser fields.Time-and energy-resolved photoelectron energy spectra are calculated for describing three photoionization channels.The population transfers through the LICS and the Raman coupling passages and discussed.

  14. Mechanisms of two-color laser-induced field-free molecular orientation

    OpenAIRE

    Spanner, Michael; Patchkovskii, Serguei; Frumker, Eugene; Corkum, Paul

    2012-01-01

    Two mechanisms of two-color (\\omega + 2\\omega) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism lea...

  15. Radiative lifetimes in B I using ultraviolet and vacuum-ultraviolet laser-induced fluorescence

    Science.gov (United States)

    O'Brian, T. R.; Lawler, J. E.

    1992-01-01

    Radiative lifetimes of the eight lowest even parity levels in the doublet system of B I are measured using time-resolved laser-induced fluorescence in the UV and VUV on an atomic beam of boron. The accurate lifetimes provide a base for improved determination of absolute transition probabilities in B I. The techniques described are broadly applicable to measurement of lifetimes of levels with transitions in the visible, UV, and VUV in almost any element.

  16. Laser-induced acoustic wave generation/propagation/interaction in water in various internal channels

    OpenAIRE

    Ko, Seung Hwan; Lee, Daeho; Pan, Heng; Ryu, Sang-Gil; Grigoropoulos, Costas P.; Kladias, Nick; Panides, Elias; Domoto, Gerald A.

    2010-01-01

    Short pulsed laser-induced single acoustic wave generation, propagation, interaction within a water-filled internal channel are experimentally and numerically studied. A large-area, short-duration, single-plane acoustic wave was generated by the thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid–solid interface and propagated at the speed of sound in water. Laser flash Schlieren photography was used to visualize the transient interaction of the plane acousti...

  17. New energy levels of atomic niobium by laser induced fluorescence spectroscopy in the near infrared

    International Nuclear Information System (INIS)

    Laser-induced fluorescence spectroscopy was applied in order to find new energy levels of the niobium atom. A continuous wave tuneable titanium–sapphire laser in the wavelength range from 750 to 865 nm and a hollow-cathode lamp were used. We discovered four energy levels of even parity, three lying levels below 19 000 cm−1 and one at much higher energy. Additionally hyperfine structure data of six levels of odd parity were determined. (paper)

  18. Ultraviolet-laser-induced desorption of atoms, ions, and molecules from lithium niobate

    International Nuclear Information System (INIS)

    We report measurements of ultraviolet-laser-induced desorption of atoms, ions, and molecules from the surface of single-crystal, Y-cut lithium niobate at intensities below the plasma threshold. Particularly striking is the desorption of LiNbO3 molecules at intensities well below the threshold for the atomic and ion emission. Measurement of oxygen and niobium yields above and below the plasma threshold show changes in surface stoichiometry

  19. Laser-induced breakdown spectroscopy for real time and online elemental analysis

    OpenAIRE

    Rai, V. N.; Rai, Awadhesh K.; Yueh, Fang-Yu; Singh, J P

    2014-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a laser based diagnostics used to study atomic emission from the expanding plasma plume formed during the laser-matter interaction. It provides valuable information about the composition of the target material. LIBS has proved its potential application in the analysis of impurities, pollutants and toxic elements in various types of matrices of different samples (solid, liquid and gases), even those present under difficult and harsh environmental ...

  20. Multi-target PCR analysis by capillary electrophoresis and laser-induced fluorescence

    Science.gov (United States)

    Lu, Wei; Han, Dai-Shu; Yuan, Ju; Andrieu, Jean-Marie

    1994-03-01

    Quantitative analysis of polymerase chain reaction (PCR) amplified HIV-1 DNA or cDNA fragments is attained using an automated system that combines capillary-gel electrophoresis (CGE) for high-efficiency separation and laser-induced fluorescence (LIF) for high-sensitivity detection. This system enables the detection of PCR-amplified multiple target DNA or cDNA in the same tube by a single injection with high precision.

  1. Laser-induced fluorescence ion diagnostics in light of plasma processing

    Energy Technology Data Exchange (ETDEWEB)

    McWilliams, R. [Department of Physics and Astronomy, University of California, Irvine 92697 (United States)]. E-mail: mcw@uci.edu; Booth, J.P. [Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, 91128 Palaiseau (France)]. E-mail: booth@lptp.polytechnique.fr; Hudson, E.A. [Lam Research Corporation, 4650 Cushing Parkway, Fremont, CA 94538 (United States)]. E-mail: eric.hudson@lamrc.com; Thomas, J. [Department of Physics and Astronomy, University of California, Irvine 92697 (United States)]. E-mail: jthomas@digitallaunchpad.com; Zimmerman, D. [Department of Physics and Astronomy, University of California, Irvine 92697 (United States)]. E-mail: dzimmerman@tosc.com

    2007-04-23

    A brief overview of non-perturbing light diagnostics is followed by recent examples of process plasma properties measured via laser-induced fluorescence (LIF), optical emission, and absorption spectroscopy. Examples include radical density measurement via absorption and emission spectroscopy. With LIF, examples show properties of ion beam etching sources and ion velocity angle variations in ICP sheaths near a process surface. Because of the wide range of process plasma parameters, appropriate choice of light diagnostics varies.

  2. Laser-Induced Conversion of Silica into Nanosized Carbon- Polyoxocarbosilane Composites

    Czech Academy of Sciences Publication Activity Database

    Pola, Josef; Bakardjieva, Snejana; Maryško, Miroslav; Vorlíček, Vladimír; Šubrt, Jan; Bastl, Zdeněk; Galíková, Anna; Ouchi, A.

    2007-01-01

    Roč. 111, č. 45 (2007), s. 16818-16826. ISSN 1932-7447 R&D Projects: GA AV ČR(CZ) IAA400720619 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z10100520; CEZ:AV0Z10100521; CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : laser-induced plasma * toluene * polyoxocarbosilane Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Laser induced chemical vapour deposition of TiN coatings at atmospheric pressure

    OpenAIRE

    Croonen, Y.; Verspui, G.

    1993-01-01

    Laser induced Chemical Vapour Deposition of a wide variety of materials has been studied extensively at reduced pressures. However, for this technique to be economically and industrially applicable, processes at atmospheric pressure are preferred. A model study was made on the substrate-coating system molybdenum-titaniumnitride focussing on the feasibility to deposit TiN films locally at atmospheric pressure. The results of this study turned out to be very promising. A Nd-YAG laser beam ([MAT...

  4. Detection of human colonic adenoma by laser-induced autofluorescence integrated with diffuse reflectance spectroscopy

    Science.gov (United States)

    Tang, Guilin; Lu, Haibao; Zhang, Yangde; Yan, Shuhua; Chen, Zhifeng

    2000-10-01

    A combined in vivo measurement system integrating laser- induced autofluorescence (LIAF) and diffuse reflectance spectroscopy (DRS) measurement was developed and investigated for detecting colonic adenoma. The system could work with regular endoscopy examination. A three- layer backpropagating neural network (BNN) was built to differentiate the two tissue classes. The preliminary results gave the mean predictive accuracy, sensitivity and specificity better than either of the two methods used alone.

  5. Robust process windows for laser induced forward transfer of thin film metal to create interconnects

    OpenAIRE

    Oosterhuis, G.; Giesbers, M.P.; Melick, P.A.J. van; Hoppenbrouwers, M.B.; Prenen, A. M.; Huis in ‘t Veld, A.J.; Knippels, G.

    2012-01-01

    Direct-write technologies can form a low-cost, alternative approach to create electrical interconnects by eliminating mask and etch costs. Also, direct-write is more efficient in creating complex structures as well as for producing small series. However, existing, industrially-mature direct-write technologies typically lack the resolution required for advanced IC packaging applications [1-4]. Laser Induced Forward Transfer (LIFT) is a direct write process which has been proven to be capable o...

  6. Analysis of laser-induced fluorescence spectra of in vitro plant tissue cultures

    Science.gov (United States)

    Muñoz-Muñoz, Ana Celia; Gutiérrez-Pulido, Humberto; Rodríguez-Domínguez, José Manuel; Gutiérrez-Mora, Antonia; Rodríguez-Garay, Benjamín; Cervantes-Martínez, Jesús

    2007-04-01

    We demonstrate the effectiveness of laser-induced fluorescence (LIF) for monitoring the development and stress detection of in vitro tissue cultures in a nondestructive and noninvasive way. The changes in LIF spectra caused by the induction of organogenesis, the increase of the F690/F740 ratio as a result of the stress originated in the organogenic explants due to shoot emergence, and the relationship between fluorescence spectra and shoot development were detected by LIF through closed containers of Saintpaulia ionantha.

  7. Research of Confocal Laser Induced Fluorescence Detection System for Micro-fluidic Chip

    Institute of Scientific and Technical Information of China (English)

    FENG Jin-yuan; WANG Xiu-hua; ZHANG Hua-feng

    2007-01-01

    The characteristics such as signal noise ratio(SNR)[1-2] and sensitivity of the fluorescence detection system for micro-fluidic chip influence the performance of the whole system extremely.The confocal laser induced fluorescence detection system is presented.Based on the debugging of optical and circuit modules, the results of detecting the samples are given and analyzed theoretically,and the improved project is put forward.

  8. Laser-induced bound-state phases in high-order harmonic generation

    DEFF Research Database (Denmark)

    Etches, Adam; B. Gaarde, Mette; Bojer Madsen, Lars

    2012-01-01

    We present single-molecule and macroscopic calculations showing that laser-induced Stark shifts contribute significantly to the phase of high-order harmonics from polar molecules. This is important for orbital tomography, where phases of field-free dipole matrix elements are needed in order to...... reconstruct molecular orbitals. We derive an analytical expression that allows the first-order Stark phase to be subtracted from experimental measurements....

  9. Enhanced acoustic cavitation following laser-induced bubble formation : long-term memory effect

    OpenAIRE

    Yavaṣ, Oğuz; Leiderer, Paul; Park, Hee K.; Grigoropoulos, Costas P.; Poon, Chie C.; Tam, Andrew C.

    1994-01-01

    The enhancement of acoustic caviation at a liquid-solid interface following laser-induced bubble formation is studied. The experiment results indicate that metastable ultramicroscopic bubbles formed on the solid surface cause a long-term memory effect on acoustic cavitation. By performing a double-pulse experiment using two excimer lasers, the temporal decay of this memory effect is determined for two different liquids on a chromium surface. An explanation of the observed decay mode by a ...

  10. Quantitative measurements in laser-induced plasmas using optical probing. Final report

    International Nuclear Information System (INIS)

    Optical probing of laser induced plasmas can be used to quantitatively reconstruct electron number densities and magnetic fields. Numerical techniques for extracting quantitative information from the experimental data are described. A computer simulation of optical probing is used to determine the quantitative information that can be reasonably extracted from real experimental interferometric systems to reconstruct electron number density distributions. An example of a reconstructed interferogram shows a steepened electron distribution due to radiation pressure effects

  11. Laser Induced Breakdown Spectroscopy for Classification of High Energy Materials using Elemental Intensity Ratios

    OpenAIRE

    Sreedhar, S.; Manoj Kumar Gundawar; Venugopal Rao, S.

    2014-01-01

    A simple, yet efficient, methodology is proposed to classify three high energy materials (HEMs) with diverse composition using nanosecond laser induced breakdown spectroscopic data. We have calculated O/N, N/H, and O/H elemental peaks ratios using a ratiometric method. The present work describes a novel way to construct 1D, 2D, and 3D classification model using the above mentioned ratios. Multivariate statistical methods are followed for construction of the classification models. A detailed p...

  12. Laser-induced damage of 1064-nm narrow-band interference filters under different laser modes

    Institute of Scientific and Technical Information of China (English)

    Weidong Gao(高卫东); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)

    2004-01-01

    The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode.The absorption measurement of such coatings has been performed by surface thermal lensing(STL)technique.The relationship between damage morphology and absorption under the two different laser modes was studied in detail.The explanation was given by the standing-wave distribution theory.

  13. Direct test of defect mediated laser induced melting theory for two dimensional solids

    OpenAIRE

    Chaudhuri, Debasish; Sengupta, Surajit

    2005-01-01

    We investigate by direct numerical solution of appropriate renormalization flow equations, the validity of a recent dislocation unbinding theory for laser induced freezing/melting in two dimensions. The bare elastic moduli and dislocation fugacities which are inputs to the flow equations are obtained for three different 2-d systems (hard disk, inverse $12^{th}$ power and the Derjaguin-Landau-Verwey-Overbeek potentials) from a restricted Monte Carlo simulation sampling only configurations {\\em...

  14. Role of echography in diagnostic dilemma in choroidal masses

    Directory of Open Access Journals (Sweden)

    Kopal N Mithal

    2014-01-01

    Full Text Available Purpose: To evaluate the role of echography in diagnosis and management of a diverse array of choroidal masses. Materials and Methods: Sixty-two cases of clinically suspected choroidal masses were prospectively analyzed with B-scan (10 Hz, A-scan, and ultrasound biomicroscopy (UBM (50 Hz after a meticulous history and ocular examination. Ancillary investigations and systemic evaluation were also done. Results: Based on clinical suspicion, acoustic features, response to treatment, and other ancillary tests combined together, the various masses were differentiated. The cases included in the study were as follows: n = 10 malignant melanomas, n = 16 metastasis and infiltrations, n = 9 hemangioma, n = 7 tuberculoma, n = 8 nonspecific inflammatory masses, n = 2 disciform plaques, n = 4 macular cysts or retinoschisis, n = 2 Coat′s disease, n = 1 melanocytoma, and n = 2 osteomas. Ultrasonography (USG alone could identify n = 51 lesions, while UBM in combination with USG was needed in remaining 11 masses. Conclusion: Standardized echography is an important adjunct in the diagnosis and management of eyes with intraocular masses. A better understanding of the clinicopathological and echographic picture of the diverse lesions can help in detection, differentiation, diagnosis, proposing a therapeutic approach, and also monitoring response to treatment. Echography is essential to evaluate tumors for extrascleral and anterior segment extension.

  15. Ageing choroid plexus and experimental models: morphometrical study

    International Nuclear Information System (INIS)

    Morphometric parameters of the light and dark rat choroid plexus epithelial cells were studied during development, after hypokinesia and low doses of ionizing radiation. Morphometric investigations were performed on semi-thin sections by using a point-counting (625 test points) method, performed with combined greed in the ocular of the light microscope for linear and planimetric estimations. Morphometric investigations in the present study and literature data provide further evidence that light and dark choroid plexus epithelial cells finish their differentiation on 30 days postnatum. The cell area of the dark epithelial cells is smaller than the cell area of the light cells and its difference retains up to 22 months. The relative part of the dark cells increases during ontogenesis and at 13 months it is larger than the relative part of the light cells. Morphometric changes of the epithelial cells during development suggest that dark and light cells are modulations of the same basic cells with possible functional differentiation starting from 17 days postconception and continue to 22 months. Morphometric changes of the light and dark epithelial cells during hypokinesia and low doses of ionizing radiation are different for light and dark cells and they depend on the kind of influence. They may be related with differences in the functional activity of the light and dark epithelial cells, specific for the applied extremum influence. (author)

  16. Thrombospondin-1 Expression in RPE and Choroidal Neovascular Membranes

    Institute of Scientific and Technical Information of China (English)

    Shikun He; Francesca Incardona; Manlin Jin; Stephen J. Ryan; David R. Hinton

    2006-01-01

    Purpose: To investigate the expression of thrombospondin 1 (TSP-1) in retinal pigment epithelium (RPE) and choroidal neovascular membranes (CNVMs) from patients with age-related macular degeneration (AMD).Methods: Tissue sections from normal human fetal and adult eyes and surgically removed CNVMs were immunostained for TSP-1 localization. Polymerase chain reaction and Western blotting were used to analyze TSP-1 mRNA and protein from human RPE cells, respectively. TSP-1 in the supernatant of cultured RPE cells and eye explants were measured using enzyme-linked immunosorbent assay. MTT assay was used to evaluate the RPE survival after TSP-1 treatment.Results: The strongest immunostaining for TSP-1 was observed in the RPE monolayer around drusen in early AMD. The intensity of TSP-1 staining in normal eye sections was much weaker than that of early AMD and CNVM. TSP-1 mRNA was positive in cultured fetal and adult RPE cells. There was increasing secretion of TSP-1 into the supernatant of cultured RPE and eye explants. The specific band of TSP-1 was identified by Western blot. No significant inhibition of RPE survival was found with the exposure to TSP-1.Conclusions: TSP-1 expression in drusen and CNVM was upregulated and associated with RPE monolayer. TSP-1 may be a natural negative regulator for choroidal neovascularization.

  17. Pelvis metastasis from primary choroidal melanoma: a case report

    Directory of Open Access Journals (Sweden)

    Xiong Y

    2014-11-01

    Full Text Available Yan Xiong, Yun Lang, Chongqi Tu, Hong Duan Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, People's Republic of China Abstract: The patient, a 16-year-old girl, was admitted to our hospital with complaints of right hip pain and claudication. Her past medical history indicated that 2 years earlier she had undergone enucleation of her left eye for a primary choroidal melanoma. Imaging studies revealed a osteolytic destruction with soft tissue mass involving the right hemipelvis (zone I–II. Single-photon emission computed tomography (SPECT and positron emission tomography–computed tomography (PET–CT showed no other sites of metastases. Consequently, the patient underwent hemipelvic prosthesis reconstruction after tumor resection. Postoperative pathological diagnosis was metastatic malignant melanoma. Thirty months after treatment, imaging studies indicated no evidence of recurrence, and functional recovery was excellent. To our knowledge, the literature does not reveal any previously reported cases of ocular choroidal melanoma that metastasized to pelvis, meanwhile was carried out hemipelvic prosthesis reconstruction after pelvic tumor resection. Keywords: melanoma, metastasis, pelvis, tumor, reconstruction

  18. Quantitative analysis of essential oils of Thymus daenensis using laser-induced fluorescence and Raman spectroscopy.

    Science.gov (United States)

    Khoshroo, H; Khadem, H; Bahreini, M; Tavassoli, S H; Hadian, J

    2015-11-10

    Laser-induced fluorescence and Raman spectroscopy are used for the investigation of different genotypes of Thymus daenensis native to the Ilam province of Iran. Different genotypes of T. daenensis essential oils, labeled T1 through T7, possess slight differences with regard to the composition of the thymol. The gas chromatography-mass spectrometry (GC-MS) method is performed to determine the concentration of each constituent as a reference method. The Raman spectra of different concentrations of pure thymol dissolved in hexane as standard samples are obtained via a laboratory prototype Raman spectroscopy setup for the calculation of the calibration curve. The regression coefficient and limit of detection are calculated. The possibility of the differentiation of different genotypes of T. daenensis is also examined by laser-induced fluorescence spectroscopy, although we do not know the exact amounts of their components. All the fluorescence spectral information is used jointly by cluster analysis to differentiate between 7 genotypes. Our results demonstrate the acceptable precision of Raman spectroscopy with GC-MS and corroborate the capacity of Raman spectroscopy in applications in the quantitative analysis field. Furthermore, the cluster analysis results show that laser-induced fluorescence spectroscopy is an acceptable technique for the rapid classification of different genotypes of T. daenensis without having any previous information of their exact amount of constituents. So, the ability to rapidly and nondestructively differentiate between genotypes makes it possible to efficiently select high-quality herbs from many samples. PMID:26560783

  19. In vivo study of the human skin by the method of laser-induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    The goals of this study are to perform a preliminary evaluation of the diagnostic potential of noninvasive laser-induced auto-fluorescence spectroscopy (LIAFS) for human skin and optimize of detection and diagnosis of hollow organs and skin. In recent years, there has been growing interest in the use of laser-induced fluorescence to discriminate disease from normal surrounding tissue. The most fluorescence studies have used exogenous fluorophores of this discrimination. The laser-induced auto-fluorescence which is used for diagnosis of tissues in the human body avoids administration of any drugs. In this study a technique for optical biopsy of in vivo human skin is presented. The auto-fluorescence characterization of tissue relies on different spectral properties of tissues. It was demonstrated a differentiation between normal skin and skin with vitiligo. Two main endogenous fluorophores in the human skin account for most of the cellular auto-fluorescence for excitation wavelength 337 nm reduced from of nicotinamide adenine dinucleotide and collagen. The auto-fluorescence spectrum of human skin depend on main internal absorbers which are blood and melanin. In this study was described the effect caused by blood and melanin content on the shape of the auto-fluorescence spectrum of human skin. Human skin fluorescence spectrum might provide dermatologists with important information and such investigations are successfully used now in skin disease diagnostics, in investigation of the environmental factor impact or for evaluation of treatment efficiency. (authors)

  20. Spatial variability of oceanic phycoerythrin spectral types derived from airborne laser-induced fluorescence emissions

    Science.gov (United States)

    Hoge, Frank E.; Wright, C. Wayne; Kana, Todd M.; Swift, Robert N.; Yungel, James K.

    1998-07-01

    We report spatial variability of oceanic phycoerythrin spectral types detected by means of a blue spectral shift in airborne laser-induced fluorescence emission. The blue shift of the phycoerythrobilin fluorescence is known from laboratory studies to be induced by phycourobilin chromophore substitution at phycoerythrobilin chromophore sites in some strains of phycoerythrin-containing marine cyanobacteria. The airborne 532-nm laser-induced phycoerythrin fluorescence of the upper oceanic volume showed distinct segregation of cyanobacterial chromophore types in a flight transect from coastal water to the Sargasso Sea in the western North Atlantic. High phycourobilin levels were restricted to the oceanic (oligotrophic) end of the flight transect, in agreement with historical ship findings. These remotely observed phycoerythrin spectral fluorescence shifts have the potential to permit rapid, wide-area studies of the spatial variability of spectrally distinct cyanobacteria, especially across interfacial regions of coastal and oceanic water masses. Airborne laser-induced phytoplankton spectral fluorescence observations also further the development of satellite algorithms for passive detection of phytoplankton pigments. Optical modifications to the NASA Airborne Oceanographic Lidar are briefly described that permitted observation of the fluorescence spectral shifts.

  1. Frequency domain and wavelet analysis of the laser-induced plasma shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Miloš, E-mail: milosb@ff.bg.ac.rs; Nikolić, Zoran

    2015-08-01

    In addition to optical emission, another trace of interest that laser-induced plasma provides is a form of acoustic feedback. The acoustic emission (AE) signals were obtained using both microphone and piezo transducers. This kind of optoacoustic signals have some distinct features resembling the short, burst-like sounds, that may differ significantly depending mainly on the sample exposed and irradiance applied. Experiments were performed on atmospheric pressure by irradiating various metallic samples. The recorded waveforms were examined and numerically processed. Single-shot acoustical spectra have shown significant potential of providing valuable supplementary information regarding plasma propagation dynamics. Moreover, the general approach suggests the possibility of making the whole measurement system cost-effective and portable. - Highlights: • We report acoustical waveform, and acoustical spectroscopy measurements and analysis in a laser-induced plasma of a different metals in air. • Both piezo and microphone transducer were used. • The acoustical spectra of the emission were obtained when the sample (and plasma) were enclosed in experimental chamber. • The acquired acoustical spectra are time-integrated and the frequency peaks were sharp and relatively isolated. • Finally, both time and frequency resolved wavelet spectrogram present a novel method of observing laser-induced plasma behavior.

  2. Laser induced micro plasma processing of polymer substrates for biomedical implant applications

    Science.gov (United States)

    French, P. W.; Rosowski, A.; Murphy, M.; Irving, M.; Sharp, M. C.

    2015-07-01

    This paper reports the experimental results of a new hybrid laser processing technique; Laser Induced Micro Plasma Processing (LIMP2). A transparent substrate is placed on top of a medium that will interact with the laser beam and create a plasma. The plasma and laser beam act in unison to ablate material and create micro-structuring on the "backside" of the substrate. We report the results of a series of experiments on a new laser processing technique that will use the same laser-plasma interaction to micromachining structures into glass and polymer substrates on the "topside" of the substrate and hence machine non-transparent material. This new laser processing technique is called Laser Induced Micro Plasma Processing (LIMP2). Micromachining of biomedical implants is proving an important enabling technology in controlling cell growth on a macro-scale. This paper discusses LIMP2 structuring of transparent substrate such as glasses and polymers for this application. Direct machining of these materials by lasers in the near infrared is at present impossible. Laser Induced Micro Plasma Processing (LIMP2) is a technique that allows laser operating at 1064 nm to machine microstructures directly these transparent substrates.

  3. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, Santiago [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico)], E-mail: camachol@cicese.mx; Evans, Rodger [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico); Escobar-Alarcon, Luis [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Miguel A. [Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n, esq. Jesus Carranza, Toluca, Estado de Mexico 50120 (Mexico); Camacho-Lopez, Marco A. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Tollocan s/n, esq. Paseo Colon, Toluca, Estado de Mexico, 50110 (Mexico)

    2008-12-30

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO{sub 2} in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance.

  4. Plasma diagnostics from self-absorbed doublet lines in laser-induced breakdown spectroscopy

    Science.gov (United States)

    D'Angelo, C. A.; Garcimuño, M.; Díaz Pace, D. M.; Bertuccelli, G.

    2015-10-01

    In this paper, a generalized approach is developed and applied for plasma characterization and quantitative purposes in laser-induced breakdown spectroscopy (LIBS) experiences by employing a selected pair of spectral lines belonging to the same multiplet. It is based on the comparison between experimental ratios of line parameters and the theoretical calculus obtained under the framework of a homogeneous plasma in local thermodynamic equilibrium. The applicability of the method was illustrated by using the atomic resonance transitions 279.55-280.27 nm of Mg II, which are usually detected in laser-induced plasma (LIP) during laser ablation of many kinds of targets. The laser induced plasmas were produced using a Nd:YAG laser from a pressed pellet of powdered calcium hydroxide with a concentration of 300 ppm of Mg. The experimental ratios for peak intensities, total intensities and Stark widths were obtained for different time windows and matched to the theoretical calculus. The temperature and the electron density of the plasma, as well as the Mg columnar density (the atom/ion concentration times the length of the plasma along the line-of-sight), were determined. The results were interpreted under the employed approach.

  5. PIC-DSMC analysis on interaction of a laser induced discharge and shock wave

    Science.gov (United States)

    Shimamura, Kohei

    2015-09-01

    Laser induced discharge and the shock wave have attracted great interest for use in the electrical engineering. When the high intensity laser (10 GW >) is focused in the atmosphere, the breakdown occurs and the discharge wave propagates toward to the laser irradiation. The shock wave is generated around the discharge wave, which is called as the laser supported detonation wave. After breakdown occurred, the initial electron of the avalanche ionization is produced by the photoionization due to the plasma radiation. It is well recognized that the radiation of the laser plasma affects the propagation mechanism of the laser induced discharge wave after the initiation of the breakdown. However, it is difficult to observe the interaction between the plasma radiation and the electron avalanche in the ionization-wave front in experimentally except in the high intensity laser. In the numerical calculation of the laser-induced discharge, the fluid dynamics based on the Navier-Stokes equation have been widely used. However, it is difficult to investigate the avalanche ionization at the wave front using the fluid dynamics simulation. To investigate the interaction of the ionization-wave front and the shock wave, it is appropriate to utilize the PIC-DSMC method. The present study showed the propagation of the ionization front of the discharge wave and the shock wave using the particle simulation. This work was supported by Kato Foundation for Promotion of Science and Japan Power Academy.

  6. Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

    International Nuclear Information System (INIS)

    Transient laser plasma is generated in laser-induced optical breakdown (LIOB). Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS) techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm-3 measured approximately 10μs and 1μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Honl-London factors

  7. Optimization of laser-induced breakdown spectroscopy for coal powder analysis with different particle flow diameters

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Shunchun, E-mail: epscyao@scut.edu.cn [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); State Key Laboratory of Pulsed Power Laser Technology, Electronic Engineering Institute, Hefei 230037 (China); Xu, Jialong; Dong, Xuan; Zhang, Bo; Zheng, Jianping [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Lu, Jidong, E-mail: jdlu@scut.edu.cn [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China)

    2015-08-01

    The on-line measurement of coal is extremely useful for emission control and combustion process optimization in coal-fired plant. Laser-induced breakdown spectroscopy was employed to directly analyze coal particle flow. A set of tapered tubes were proposed for beam-focusing the coal particle flow to different diameters. For optimizing the measurement of coal particle flow, the characteristics of laser-induced plasma, including optical breakdown, the relative standard deviation of repeated measurement, partial breakdown spectra ratio and line intensity, were carefully analyzed. The comparison of the plasma characteristics among coal particle flow with different diameters showed that air breakdown and the random change in plasma position relative to the collection optics could significantly influence on the line intensity and the reproducibility of measurement. It is demonstrated that the tapered tube with a diameter of 5.5 mm was particularly useful to enrich the coal particles in laser focus spot as well as to reduce the influence of air breakdown and random changes of plasma in the experiment. - Highlights: • Tapered tube was designed for beam-focusing the coal particle flow as well as enriching the particles in laser focus spot. • The characteristics of laser-induced plasma of coal particle flow were investigated carefully. • An appropriate diameter of coal particle flow was proven to benefit for improving the performance of LIBS measurement.

  8. Laser induced plasma on copper target, a non-equilibrium model

    International Nuclear Information System (INIS)

    The aim of this work is to present a comprehensive numerical model for the UV laser ablation of metal targets, it focuses mainly on the prediction of laser induced plasma thresholds, the effect of the laser-plasma interaction, and the importance of the electronic non-equilibrium in the laser induced plume and its expansion in the background gas. This paper describes a set of numerical models for laser-matter interaction between 193-248 and 355 nm lasers and a copper target. Along with the thermal effects inside the material resulting from the irradiation of the latter with the pulsed laser, the laser-evaporated matter interaction and the plasma formation are thoroughly modelled. In the laser induced plume, the electronic nonequilibrium and the laser beam absorption have been investigated. Our calculations of the plasmas ignition thresholds on copper targets have been validated and compared to experimental as well as theoretical results. Comparison with experiment data indicates that our results are in good agreement with those reported in the literature. Furthermore, the inclusion of electronic non-equilibrium in our work indicated that this important process must be included in models of laser ablation and plasma plume formation

  9. Laser induced plasma on copper target, a non-equilibrium model

    Energy Technology Data Exchange (ETDEWEB)

    Oumeziane, Amina Ait, E-mail: a.aitoumeziane@gmail.com; Liani, Bachir [Laboratoire de Physique Théorique, Abou Beker Blekaid University, Tlemcen (Algeria); Parisse, Jean-Denis [IUSTI UMR CNRS 7343, Aix-Marseille University, Marseille (France)

    2014-02-15

    The aim of this work is to present a comprehensive numerical model for the UV laser ablation of metal targets, it focuses mainly on the prediction of laser induced plasma thresholds, the effect of the laser-plasma interaction, and the importance of the electronic non-equilibrium in the laser induced plume and its expansion in the background gas. This paper describes a set of numerical models for laser-matter interaction between 193-248 and 355 nm lasers and a copper target. Along with the thermal effects inside the material resulting from the irradiation of the latter with the pulsed laser, the laser-evaporated matter interaction and the plasma formation are thoroughly modelled. In the laser induced plume, the electronic nonequilibrium and the laser beam absorption have been investigated. Our calculations of the plasmas ignition thresholds on copper targets have been validated and compared to experimental as well as theoretical results. Comparison with experiment data indicates that our results are in good agreement with those reported in the literature. Furthermore, the inclusion of electronic non-equilibrium in our work indicated that this important process must be included in models of laser ablation and plasma plume formation.

  10. Optimization of laser-induced breakdown spectroscopy for coal powder analysis with different particle flow diameters

    International Nuclear Information System (INIS)

    The on-line measurement of coal is extremely useful for emission control and combustion process optimization in coal-fired plant. Laser-induced breakdown spectroscopy was employed to directly analyze coal particle flow. A set of tapered tubes were proposed for beam-focusing the coal particle flow to different diameters. For optimizing the measurement of coal particle flow, the characteristics of laser-induced plasma, including optical breakdown, the relative standard deviation of repeated measurement, partial breakdown spectra ratio and line intensity, were carefully analyzed. The comparison of the plasma characteristics among coal particle flow with different diameters showed that air breakdown and the random change in plasma position relative to the collection optics could significantly influence on the line intensity and the reproducibility of measurement. It is demonstrated that the tapered tube with a diameter of 5.5 mm was particularly useful to enrich the coal particles in laser focus spot as well as to reduce the influence of air breakdown and random changes of plasma in the experiment. - Highlights: • Tapered tube was designed for beam-focusing the coal particle flow as well as enriching the particles in laser focus spot. • The characteristics of laser-induced plasma of coal particle flow were investigated carefully. • An appropriate diameter of coal particle flow was proven to benefit for improving the performance of LIBS measurement

  11. High spatial resolution in laser-induced breakdown spectroscopy of expanding plasmas

    International Nuclear Information System (INIS)

    We report a technique that is able to achieve high spatial resolution in the measurement of the temporal and spectral emission characteristics of laser-induced expanding plasmas. The plasma is imaged directly onto the slit of an imaging spectrograph coupled to a time-gated intensified camera, with the plasma expansion direction being parallel to the slit extension. In this way, a single hybrid detection system is used to acquire the spatial, spectral and temporal characteristics of the laser induced plasma. The parallel acquisition approach of this technique ensures a much better spatial resolution in the expansion direction, reproducibility and data acquisition speed than commonly obtained by sequential measurements at different distances from the target. We have applied this technique to study the laser-induced plasma in LiNbO3 and Bi12Ge1O20, revealing phenomena not seen in such detail with standard instruments. These include extreme line broadening up to a few nanometers accompanied by self-absorption near the target surface, as well as different ablation and expansion dynamics for the different species ejected. Overall, the high precision and wealth of quantitative information accessible with this technique open up new possibilities for the study of fundamental plasma expansion processes during pulsed laser ablation

  12. Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

    Directory of Open Access Journals (Sweden)

    Christian G. Parigger

    2010-01-01

    Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

  13. Study of concentric iridescent ring around the laser-induced pits on the solar cell surface

    International Nuclear Information System (INIS)

    Highlights: • We studied the laser-induced damage on solar cell surface. • Concentric iridescent ring was observed originated from the gradient distribution pattern of the thickness of the oxidized surface film. • The damaged surface film of the m-Si solar cell is SiO2, while that of the GaAs/Ge solar cell is GeO2. - Abstract: The laser-induced damage on the surface of monocrystalline silicon (m-Si) solar cells and GaAs/Gesingle heterojunction solar cells are investigated. The solar cells were irradiated by a continuous wave laser at the wavelength of 532 nm. Concentric iridescent ring appeared on the damaged surfaces when observed with an optical microscope (OM) of broad spectrum. The damaged surface film was characterized by X-ray photoelectron spectroscopy (XPS) and the Contour Meter. The laser-induced temperature in silicon was calculated. The formation mechanism of the film and the cause of the concentric iridescent ring were analyzed

  14. Addressing the Numerical Challenges Associated With Laser-Induced Melt Convection

    Science.gov (United States)

    Weston, Brian; Nourgaliev, Robert; Delplanque, Jean Pierre; Anderson, Andy

    2015-11-01

    We present a new robust and efficient numerical framework for simulating multi-material flows with phase change. The work is motivated by laser-induced phase change applications, particularly the selective laser melting (SLM) process in additive manufacturing. Physics-based simulations of the laser melt dynamics requires a fully compressible framework, since incompressible flow solvers are inefficient for stiff systems, arising from laser-induced rapid phase change. In this study, the liquid and solid phases are both modeled with the compressible Navier-Stokes equations. The solid phase has an additional combined variable viscosity and drag force model to suppress the velocity in the solid. Our all-speed Navier-Stokes solver is based on a fully-implicit, high-order reconstructed Discontinuous Galerkin method. A Newton-Krylov based framework is used to solve the resulting set of non-linear equations, enabling robust simulations of the highly stiff compressible Navier-Stokes equations. We demonstrate the method's capabilities for phase change on several different melting and freezing configurations, including a three-dimensional laser-induced melt convection problem. Future model enhancements will incorporate material evaporation and rapid solidification.

  15. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    International Nuclear Information System (INIS)

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO2 in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance

  16. Variational study of the constituents of cholesterol stones by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Singh, Vivek K; Rai, Vinita; Rai, A K

    2009-01-01

    The major and minor constituents of cholesterol gallstones were investigated by Laser-induced breakdown spectroscopy. The elements detected in the center and in the shell part were calcium (Ca), carbon (C), copper (Cu), hydrogen (H), magnesium (Mg), nitrogen (N), sodium (Na), oxygen (O) and potassium (K), but Cu was absent from the surface of the cholesterol gallstones. Our experimental results revealed that calcium was a major constituent of cholesterol gallstones. Our results also showed that the concentration of Ca, Cu and Mg were large in the center in comparison with the shell. Laser-induced breakdown (LIB) spectra of both portions of the surface (colored part and discolored part) of the cholesterol gallstones were recorded. The concentrations of sodium and potassium were higher in the non-pigmented (colored) part than in the pigmented part (discolored/pigment), which showed that the deficiency of sodium and potassium was playing a key role in the formation of discoloration at the different locations on the outer surfaces of the cholesterol gallstones. Thus, laser-induced breakdown spectroscopy (LIBS) is a suitable technique for the analysis of cholesterol gallstones without any sample preparation. PMID:18043957

  17. Measurement of radiative lifetime in atomic samarium using simultaneous detection of laser-induced fluorescence and photoionization signals

    Indian Academy of Sciences (India)

    A C Sahoo; M L Shah; P K Mandal; A K Pulhani; G P Gupta; Vas Dev; B M Suri

    2014-02-01

    In this paper, we report the investigations of lifetime measurement of odd-parity energy level 19009.52 cm-1 of Sm I using simultaneous detection of laser-induced fluorescence and laserinduced photoionization signals employing pump–probe technique. To the best of our knowledge, this is for the first time that the results obtained using laser-induced fluorescence and photoionization techniques have been compared with each other. The obtained results match well with those reported in the literature.

  18. Cardiac, choroidal and subcutaneous metastases of a follicular thyroid carcinoma

    International Nuclear Information System (INIS)

    Full text of publication follows. Aim: to describe an unusual case of follicular carcinoma of the thyroid with uncommon metastases at the left atrium, the pulmonary vessels, the right eye and a subcutaneous mass. Materials and methods: the patient record was reviewed retrospectively. We analysed clinical outcomes and thyroglobulin rate as well as imaging findings after radio-iodine therapy. Results: we report the case of 43-year-old woman operated in 1995 for multi-nodular goitre by total thyroidectomy. Histopathologic findings were typical of follicular thyroid carcinoma with vascular invasion. The patient was then lost of sight and consulted in 2000 for a neck swelling. She was operated again for lymphadenectomy with resection of two peri-jugular tumoral masses that deviate vascular axes. Histopathologic findings concluded for residual follicular thyroid carcinoma with insular component without lymph node metastasis. The initial chest CT revealed a macro-nodular lung miliairy and the whole body scan post 100 mCi Iodine-131 showed intense cervical uptake and multiple bilateral thoracic fixations. The evolution after 10 cures of Iodine-131 has been marked by a persistently high thyroglobulin levels superior to 800 ng/ml with disappearance of cervical uptake and the persistence of pulmonary fixations. Bone scintigraphy scan was negative. Later, the patient complained of a decreased visual acuity. The last whole body SPECT/CT scan revealed multiple fixations of I-131 located at the right eyeball, lungs, left atrium, liver, sacrum as well as an abdominal subcutaneous solid mass. MRI confirmed a right choroid metastasis. Conclusion: follicular thyroid carcinoma comprises 15% of all thyroid cancers and usually metastases to the lymph nodes, lungs and bone. Other rare sites of metastases are the brain, pituitary, maxilla, larynx, and thymus. Distant metastases of these sites, particularly choroidal are exceptional. Metastatic cardiac involvement occurs most often during

  19. Effect of myopia onset time for macula choroidal thickness

    Directory of Open Access Journals (Sweden)

    Shi-Ming Wang

    2016-03-01

    Full Text Available AIM:To investigate the effect of onset time(Tfor macula choroidal thickness(CTin myopia patient. METHODS:A prospective cohort study was designed.One hundred and twenty-two myopia patients(244 eyes; 67 male and 55 female; aged 30~41 years, mean 35.1±4.6 years oldwho received preoperative examinations from March 2014 to April 2015 were recruited in this study. The patients were divided into three groups according to onset time(T:group A(T≤5a, group B(5aF=1.56,P>0.05,age(F=2.13,P>0.05,best corrected visual acuity(BCVA, F=1.41,P>0.05,corneal curvature(F=1.65,P>0.05and axial length(F=1.89,P>0.05among the three groups. The choroid in macular region was measured by enhanced depth imaging(EDIusing spectral-domain optical coherence tomography(SD-OCT. This study recorded the CT at subfoveal(SFCT, 1mm at temporal(T1mm, nasal(N1mm, superior(S1mmand inferior(I1mmto the fovea and 3mm temporal(T3mm, nasal(N3mm, superior(S3mmand inferior(I3mmto the fovea, respectively. The differences of CT at the same position among the three groups were analyzed.RESULTS:The mean SFCT for group A,B,C were 238.32±57.95μm, 230.58±67.21μm, 221.63±62.37μm respectively in this study. The CT was found no significant difference in different locations except N3mm(tA-B=4.34,P3mm(tB-C=7.61,P3mm(t=0.76,P>0.05between group A and C. Significant difference was found at N3mm(tA-B=4.31,t B-C=7.59,tA-C=12.18; PCONCLUSION:The choroidal thickness decreases as the myopia onset time is earlier, especially at nasal.

  20. Choroid plexus tumors: An institutional series of 25 patients

    Directory of Open Access Journals (Sweden)

    Menon Girish

    2010-01-01

    Full Text Available Purpose : Choroid plexus tumors (CPT are rare neoplasms that pose considerable treatment challenges. This study reviews a single institute′s experience with 25 patients of CPT and attempts to contribute to the general body of knowledge on CPT. Materials and Methods : A retrospective analysis of the case records of 25 patients operated for CPT since January 1998 and having a minimum of 1 year follow-up. Results : The study group included 12 (48% cases of choroid plexus papilloma (CPP, 09 (36% cases of choroid plexus carcinoma (CPC and 4 cases of atypical CPP. The mean age at presentation was 18.6 years (range, 6 months to 54 years; SD, 18.7 and a male preponderance was noted (17:8. Raised intracranial pressure was the commonest presenting symptom (72%. The tumors were distributed as follows: lateral ventricle (16; 64%, fourth ventricle (5; 20%, fourth ventricle with cerebellopontine angle extension (3; 12%, and third ventricle (1; 4%. A complete surgical excision was achieved in 11 cases of CPP and 8 cases of CPC. Operative complications include pneumocephalus (40%, focal deficits (36%, subdural effusion (32%, and persistent hydrocephalus requiring shunt (24%. All patients with CPP had a good outcome at the end of a mean follow-up of 5.4 years, whereas the median survival for patients with CPCs who underwent a subtotal resection with adjuvant therapy was 36 months. Conclusion : CPTs include a spectra ranging from CPP to CPC. Radiologic and histologic characterization of these tumors is difficult and newer immunohistochemical and genetic studies should be done to differentiate them from each other. Total excision offers a good prognosis and should be attempted for all forms of CPTs. CPPs carry a good prognosis, and adjuvant therapy is not indicated even after partial excision. CPCs and atypical CPCs carry a poor prognosis, and adjuvant therapy improves survival marginally after total excision. Spinal drop metastases are common for CPC and