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Low-threshold ablation of dielectrics irradiated by picosecond soft x-ray laser pulses
Get PDFAblation of LiF crystal by soft x-ray laser ͑XRL͒ pulses with wavelength = 13.9 nm and duration T L = 7 ps is studied experimentally and theoretically. It is found that a crater appears on a surface of LiF for XRL fluence, exceeding the ablation threshold F a ϳ 10.2 mJ/ cm 2 in one shot, or 5 mJ/ cm 2 in each of the three XRL shots. This is substantially below the ablation thresholds obtained with other lasers having longer pulse duration and/or longer wavelength. A mechanism of thermomechanical ablation in large bandgap dielectrics is proposed. The theory explains the low F a via small attenuation depth, absence of light reflection, and electron heat conductivity. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3152290͔ Laser ablation has many technological applications in material microprocessing and fabrication of nanostructures. 1 It is not surprising, then, that a lot of work has been done in the last decade to study the laser-induced damage of dielectrics and its connection with the pulse width and energy, size of focal spot, and wavelength ͑see Refs. 2 and 3, and references therein͒. For the relatively long ͑Ͼ20 ps͒ incident laser pulses, it was shown 2 that the majority of damage of defect-free dielectrics involves the heating of conduction band electrons and transferring of electron energy to the lattice. Damage occurs if the deposited energy is sufficient to melt or boil the dielectric material. Decreasing the pulse duration sharply diminishes the ablation threshold of dielectrics from ϳ20-40 down to ϳ2 J/ cm 2 . Such drop in threshold is connected with transition from the long pulse thermally dominated regime to an ablative regime dominated by collisional and multiphoton ionization, with production of large number of electrons in short pulse. For the short enough pulses, the laser energy is absorbed by the electrons much faster than it is transferred to the lattice. This initiates the electron avalanche resulting in damage of dielectrics. An even more efficient ablation of dielectrics could be reached by using extreme ultraviolet or soft x-ray laser ͑XRL͒ radiation due to the large linear absorption of such radiation by dielectrics. Indeed, in the recent studies, 4 a well-defined ablation threshold at 0.06 for CaF 2 and 0.11 J / cm 2 for LiF has been found for pulse energy 0.3 mJ of nanosecond Ar XRL with = 46.9 nm and L = 1.7 ns. According to analysis of ablation threshold dependencies from the pulse duration for visible lasers, the additional lowering of ablation threshold could be expected in the case of XRL pulses with the picosecond or femtosecond durations. In this letter we describe the laser ablation investigations of LiF crystals by focusing a 7 ps, 13.9 nm soft Ag XRL and the analysis of the ablative surfaces by use of luminescence, visible and atomic force microscopes ͑AFM͒. A mechanism for ablation of dielectrics by short picosecond XRL pulses is proposed and the results of the theoretical modeling in comparison with the experimental data are discussed. The experiment has been performed with the XRL facility at JAEA Kansai Photon Science Institute. 7 After irradiation of the LiF crystal with the XRL, the photoluminescence patterns from the CCs in LiF were observed by using a confocal fluorescence laser microscope ͑OLYMPUS model FV300͒. A 488 nm Ar laser has been used in the microscope to excite both CCs, which a͒ Electronic mail: [email protected]. APPLIED PHYSICS LETTERS 94, 231107 ͑2009
Observed and Projected Climatic Changes, Their Impacts and Adaptation Options for Sri Lanka: A Review
Get PDFAbstract Climate is changing world-wide, and the science community in Sri Lanka has come up with ample evidence to suggest that the country's climate has already changed. During 1961-1990 the country's mean air temperature increased by 0.016 0 C per year, and the mean annual rainfall decreased by 144 mm (7 %) compared to the period 1931-1960. In addition, mean annual daytime maximum and mean annual night-time minimum air temperatures increased. However, the bigger question of national importance is what Sri Lanka's climate will look like in 50 or 100 years and how prepared is the country to face it. Apart from the Intergovernmental Panel on Climate Change (IPCC) projections at the coarse global scale, few studies have attempted to project future climate scenarios for Sri Lanka and to identify climate change impacts on agriculture, water resources, the sea level, the plantation sector, the economy and health. Vulnerability and adaptation to climate change are the least studied areas. This paper reviews the status of climate change research and activities in Sri Lanka with respect to future climate projections, impacts, climate change mitigation and the country's ability to adapt, and identifies existing knowledge gaps. Messages emerging from this review suggest that Sri Lanka's mean temperature during the North-East (December-February) and South-West (May-September) monsoon seasons will increase by about 2.9 0 C and 2.5 0 C, respectively, over the baseline , by the year 2100 with accompanying changes in the quantity and spatial distribution of rainfall. Extreme climate events are expected to increase in frequency. These changes will bring about widespread impacts on the country's agriculture and economy. For example, an increase of 0.5 0 C in temperature can reduce rice yield by approximately 6 %; extended dry spells and excessive cloudiness during the wet season can reduce coconut yield resulting in annual losses between 73 million to the economy. Pilot studies in the Galle District suggest that sea level rise could inundate about 20 % of the land area of Galle's coastal District Secretariat Divisions. Adaptation measures already undertaken in the agriculture sector include the development of low water consuming rice varieties and the use of micro-irrigation technologies. Tools have been developed for predicting seasonal water availability within the Mahaweli Scheme and annual national coconut production. However, Sri Lanka is yet to undertake a comprehensive national study on the vulnerability of her water resources and agriculture to climate change. The formulation of detailed and reliable future climate scenarios for the country is therefore, urgently required. 100 Nishadi Eriyagama and Vladimir Smakhti
Geothermal Resources for Development in Central America -Social and Economic Valuation, Present Use and Future Opportunities
Get PDFABSTRACT In Central America, growing population, expanding economies and new markets, result in an annual rate of the electricity demand of about 6% through the year 2020. This, together with the fluctuations in the world energy markets, require to develop more reliable domestic environmentally sound electrical systems, which are precondition for a sound social and economic development of the region
Effects of 8-Week Hatha Yoga Training on Metabolic and Inflammatory Markers in Healthy, Female Chinese Subjects: A Randomized Clinical Trial
Get PDFWe aimed to determine the effects of an 8 wk Hatha yoga training on blood glucose, insulin, lipid profiles, endothelial microparticles (EMPs), and inflammatory status in healthy, lean, and female Chinese subjects. A total of 30 healthy, female Chinese subjects were recruited and randomized into control or yoga practice group. The yoga practice included 8 wks of yoga practice (2 times/wk) for a total of 16 times. Fasting blood samples were collected before and after yoga training. Plasma was isolated for the measurement of lipid profiles, glucose, insulin, EMPs, and inflammatory cytokines. Whole blood was cultured ex vivo and stimulated with lipopolysaccharide (LPS) and Pam3Cys-SK4. Peripheral blood mononuclear cells (PBMCs) were isolated for the measurement of TLR2 and TLR4 protein expression. Yoga practice significantly reduced plasma cholesterol, LDL-cholesterol, insulin levels, and CD31+/CD42b− EMPs. Cultured whole blood from the yoga group has reduced proinflammatory cytokines secretion both at unstimulated condition and when stimulated with Pam3Cys-SK4; this might be associated with reduced TLR2 protein expression in PBMCs after yoga training. Hatha yoga practice in healthy Chinese female subjects could improve hallmarks related to MetS; thus it can be considered as an ancillary intervention in the primary MetS prevention for the healthy population. This trial is registered with ChiCTR-IOR-14005747
Heart Failure Direct Renin Inhibitor Attenuates Left Ventricular Remodeling in Post-Myocardial Infarction Heart Failure Mice
Get PDFBackground: The role of direct renin inhibitors in myocardial ischemia-induced heart failure is controversial. We hypothesized that direct renin inhibitors play a positive role, affecting in vivo myocardial function as well as in vitro extracellular matrix change. Methods: Ten-week-old C57BL/6J male mice with 2-kidney 1-clip (2K1C) model were enrolled in this study. The mice were divided into 3 groups each with 18 mice; group 1 sham-operated, group 2 coronary artery ligationinduced heart failure, and group 3 coronary artery ligation-induced heart failure receiving aliskiren minipump infusion. These mice were assessed for systemic hemodynamics and left ventricular function by 2-dimensional echocardiography (iE33, Philips). Myocardial tissue was stained and crude protein was isolated from the nonischemic viable left ventricle. Myocardial tissue contents of anti-angiotensin II type 1 (AT1) receptor, matrix metalloproteinase (MMP)-2 and MMP-9 were examined. Results: There were 54 mice that received 2K1C and were followed up for three weeks. Baseline characteristics showed no difference. At follow-up, the heart failure-only group had greater left ventricular mass and worse systolic function as compared to the sham group. Whereas the heart failure-aliskiren group had lower left ventricle mass and better systolic function as compared to the heart failure-only group. AT1 receptor, MMP-2 and MMP-9 levels were increased in the heart failure-only model while direct renin inhibitor attenuated this significantly. Conclusions: Direct renin inhibitors improved myocardial function in a myocardial ischemia-induced heart failure mouse model. The improvement seen is present in myocardial mass, left ventricular systolic function and also in myocardial interstitial tissue
Redalyc.Enfermería pediátrica versus Enfermería de familia; opiniones de los profesionales y los padres de los niños de San Sebastián de los Reyes (Madrid)
No full textCorrelation between Structure of Titanium Additives and Dehydrogenation Reaction of Magnesium Borohydride Studied by Continuous Observation of X-Ray Absorption Spectroscopy
Get PDFLocal structure of Ti-based additives in Mg(BH 4 ) 2 was studied by X-ray absorption fine structure spectroscopy with conventional and dispersive mode in order to understand the correlation between the structure of the additives and dehydrogenation property of Mg(BH 4 ) 2 . Simultaneous measurement of the dehydrogenation curve and the X-ray absorption spectroscopy by the dispersive optics revealed that a part of TiCl 3 additive is converted to Ti x Mg 1À3x=2 (BH 4 ) 2 (x ¼ 0$0:67) just after ball milling mixture and then promptly resolved to TiB 2 at 100-150 C with the first dehydrogenation peak. TiO 2 additive is slowly converted to lower oxidation state in wide temperature range around the second dehydrogenation peak at 350 C where the main dehydrogenation reaction of Mg(BH 4 ) 2 occurs
Clinical Study Clinical Safety and Immunogenicity of Tumor-Targeted, Plant-Made Id-KLH Conjugate Vaccines for Follicular Lymphoma
Get PDFWe report the first evaluation of plant-made conjugate vaccines for targeted treatment of B-cell follicular lymphoma (FL) in a Phase I safety and immunogenicity clinical study. Each recombinant personalized immunogen consisted of a tumor-derived, plantproduced idiotypic antibody (Ab) hybrid comprising the hypervariable regions of the tumor-associated light and heavy Ab chains, genetically grafted onto a common human IgG1 scaffold. Each immunogen was produced in Nicotiana benthamiana plants using twin magnICON vectors expressing the light and heavy chains of the idiotypic Ab. Each purified Ab was chemically linked to the carrier protein keyhole limpet hemocyanin (KLH) to form a conjugate vaccine. The vaccines were administered to FL patients over a series of ≥6 subcutaneous injections in conjunction with the adjuvant Leukine (GM-CSF). The 27 patients enrolled in the study had previously received non-anti-CD20 cytoreductive therapy followed by ≥4 months of immune recovery prior to first vaccination. Of 11 patients who became evaluable at study conclusion, 82% (9/11) displayed a vaccine-induced, idiotype-specific cellular and/or humoral immune response. No patients showed serious adverse events (SAE) related to vaccination. The fully scalable plant-based manufacturing process yields safe and immunogenic personalized FL vaccines that can be produced within weeks of obtaining patient biopsies
Sexual Abuse of Older Residents in Nursing Homes: A Focus Group Interview of Nursing Home Staff
Get PDFThe objective of this study was to increase knowledge of sexual abuse against older residents in nursing homes. A qualitative approach was used. Through a focus group interview with staff in nursing homes, the aim was to reveal employees' thoughts, experiences, and attitudes. Findings from the focus group interview show that sexual abuse of older residents is a taboo topic among health professionals. Acts of sexual abuse are difficult to imagine; it is hard to believe that it occurs. The fact that staff are not aware that it could happen, or have a hard time believing that it actually happens, can amplify the residents' vulnerable position as potential victims of abuse, and it makes it even more challenging to report or uncover such acts. The study highlights the need for education of all health care workers in Norway as well as more research on sexual abuse against older residents in nursing homes. Furthermore, there is a need for good policies and reporting systems, as an important step towards addressing sexual abuse of the aged in a more appropriate way. Further research must aim to reveal more about this taboo area