Photo-Double Ionization of Water Molecules Using Synchrotron at ELETTRA

Synchrotron radiation is the light, i.e., photons emitted by accelerating electrons. ELETTRA operates a third-generation synchrotron with 26 beamlines in Trieste, Italy. The synchrotron is capable of generating lights at wavelengths varying from infrared to hard X-rays.The facility is used for a variety of scientific experiments from materials science to molecular physics. The Gas Phase Photoemission (GAPH) beamline was used to expose the water molecules to photons in the 60 – 70 eV range and ionize them. The GAPH beamline is capable of delivering lights of wide energy range from 13.5 eV to more than 900 eV to gaseous systems. The Multi-coincidence chamber at the beamline has ten analyzers mounted along a circle with 30 degree increments. The analyzers allow only electronsat a certain energy level (and at a specific angle) to pass, and can detect the two electrons emitted by the photo-double ionization in coincidence. The objective of the experiment was to observe photo-double ionization of water molecules by measuring the angles and energy of two electrons with equal sharing of energy (mainly direct process) at coincidence and test for molecular models of water. The data is being analyzed at this point and will be included in the poster. Future work will involveuneven sharing of the energy between the two photo-electrons, which can be both direct and indirect

Photo-Double Ionization of Water

The goal of this experiment was to measure coincident 2-electron emissions from water molecules with unequal energies to analyze the direct emission processes of H20. The ELETTRA Synchrotron was utilized for its highly tunable photon selection and its coincidence measurement capabilities. A photon flux of specific energy was fired into a thin stream of water vapor in near-perfect vacuum and electron detectors at known angles in the plane of emission were scanned through different energy and emission angles. The detectors only recorded a measurement if it was in coincidence with the measurement of another detector to ensure that all measurements, were a cause of photo-double ionization. The motivation of this experiment was a lack of documentation in the field of photon double ionization of water with unequal energy sharing due to the complexity of the H20 molecule. The data gathered will, ultimately, lead to a better understanding of the structure of the water molecule, of the photo-double ionization dynamics, which in turn could have profound biology and space physics applications, for example in the field of radiation damage

Optical and Thermal Properties of Spinel with Revised (Increased) Absorption at 4 to 5 μM Wavelengths and Comparison with Sapphire

Infrared absorption of high-quality, commercial, polycrystalline MgAl2O4 spinel is ∼40% greater in the range of 3.8 to 5.0 μm than the value predicted by the computer code OPTIMATR®, which has been used for window and dome design for more than 20 years. As a result, spinel and a-plane sapphire windows designed to support the same external pressure with the same probability of survival have approximately the same infrared absorptance in the range 3.8 to 5.0 μm. c-Plane sapphire has greater absorptance than spinel in the range 3.8 to 5.0 μm. Spinel has two weak absorption bands near 1.8 and 3.0 μm. At 1.064 μm, the laser calorimetric absorption coefficient of spinel is 10 to 50 times greater than that of sapphire. New measurements of specific heat capacity, thermal expansion, thermal conductivity, elastic constants, and refractive index (including dn∕dT) of spinel are reported

Internal Carotid Artery Occlusive Disease and Polymorphisms of Fractalkine Receptor CX3CR1

Background and Purpose— Fractalkine (FKN), a chemokine expressed by inflamed endothelium, induces leukocyte adhesion and migration via the receptor CX3CR1. The polymorphisms V249I and T280M affect receptor expression and function. The role of FKN in atherosclerosis has been recently demonstrated. The aim of this study was to investigate a possible association between CX3CR1 polymorphisms and increased risk of internal carotid artery (ICA) occlusive disease. Methods— We studied 108 patients consecutively recruited for ICA occlusive disease, 84 of whom underwent operation for carotid endarterectomy, and 204 subjects without ICA occlusive disease (controls). Polymorphic genotypes were determined by polymerase chain reaction and sequencing analysis. Results— The adjusted odds ratio (OR) associated with the presence of the M280 (TM+MM versus TT genotype) was 0.55 (95% CI: 0.29 to 0.99; P =0.037). Therefore, this allele is associated with a reduced risk of ICA occlusive disease. No significant differences were observed in I249 distribution. The frequency of I249 allele was significantly higher in cases of hard plaques, which are considered more stable than soft ones (OR: 0.38; 95% CI: 0.13 to 1.05; P =0.037). Multiple logistic regression analysis using the common risk factors and the I249 and M280 allele variants revealed that the M280 allele was an independent risk factor for ICA stenosis ( P =0.047). Conclusion— The results show that the CX3CR1 M280 is an independent genetic risk factor for ICA occlusive disease and that I249 is involved in the stability of carotid plaques. Even if obtained from a relatively limited patient series, these results might have relevant implications for treatment of ICA stenosis and possibly prevention of carotid related stroke. Further prospective cross-sectional studies are needed to confirm these results

Optical Properties of Epitaxial Single-Crystal Chemical-Vapor-Deposited Diamond

Epitaxial single-crystal chemical-vapor-deposited diamond was obtained from Element Six Ltd. (Ascot, UK) and from Apollo Diamond (Boston, MA). Both companies provided 5 x 5 mm squares with thicknesses ranging from 0.5 to 1.5 mm. In addition, Element Six provided 10-mm-diameter disks with a thickness of 1.0 mm. The absorptance of all specimens at 1064 nm was measured by laser calorimetry, with good agreement between independent measurements at the University of Central Florida and at QinetiQ (Malvern, UK). Depolarization at 1064 nm and ultraviolet absorption properties are also reported

Temperature-dependent spectroscopic properties of Tm(3+) in germanate, silica, and phosphate glasses: A comparative study

Spectroscopic properties of thulium-doped germanate, silica, and phosphate glasses were measured and compared since such glasses are of interest as materials for fiber lasers in the eye-safe wavelength region. (3)F(4) excited state fluorescence decay dynamics was investigated at temperatures from 8 to 300 K and the results revealed a strong dependence of the (3)F(4) lifetime on the host matrix. The temperature-dependent stimulated emission cross section was obtained by using the Fuchtbauer-Ladenburg technique. In phosphate glass the fluorescent lifetime is short, making this material difficult to use for 2 mu m laser purposes. Tm(3+)-doped germanate glass shows a longer lifetime than silica, a comparable value of stimulated emission cross section and some interesting temperature-independent properties

Index of Refraction from the Near-Ultraviolet to the Near-Infrared from a Single Crystal Microwave-Assisted CVD Diamond

The refractive index of a type IIa CVD-grown single-crystal diamond was measured by ellipsometry from the near ultraviolet to the near infrared region of the spectrum. As a consequence, a one term Sellmeier Equation with coefficents of B-1 = 4.658 and C-1 = 112.5 for the refractive index of diamond, for the wavelength range from 300 to 1650 nm, was derived that is only as accurate as the input data, +/- 0.002. The experimental results in this paper between 800 and 1650 nm are new, adding to the values available in the literature

Development of High-Purity Optical Grade Single-Crystal CVD Diamond for Intracavity Cooling

Microwave assisted chemical vapour deposited bulk diamond products have been used in a range of high power laser systems, due to low absorption across a range of wavelengths and exceptional thermal properties. However the application of polycrystalline products has frequently been limited to applications at longer wavelengths or thermal uses outside of the optical path due to the birefringence and scatter that are intrinsic properties of the polycrystalline materials. However, there are some solid state structures, including thin disc gain modules and amplifiers, that will gain significantly in terms of potential output powers if diamond could be used as a heat spreader in the optical path as well as a heat spreader on the rear surface of the disk. Therefore single crystal grades of diamond have been developed that overcome the limitations of the polycrystalline material, with low absorption, low scatter and low birefringence grades for demanding optical applications. We will present new data, characterising the performance of these materials across infra-red and visible wavelengths with absorption coefficient measured by laser calorimetry at a range of wavelengths from 1064 nm to 452 nm

Laparoscopic surgery does not reduce the need for red blood cell transfusion after resection for colorectal tumour: a propensity score match study on 728 patients

Background: Patients with colorectal tumour often present with anaemia, and up to 60% will receive red blood cells (RBC) transfusion. Some evidence suggests a correlation between RBC transfusion and worse outcomes. Since laparoscopy minimizes intraoperative blood loss, we retrospectively investigated its role in reducing haemoglobin (Hb) drop and requirements for postoperative RBC transfusions. Methods: Patients were identified from consecutive cases undergone elective surgery for non-metastatic colorectal tumour between 2005 and 2019. Laparoscopic cases were matched 1:1 with open controls through propensity score matching (PSM). The main outcome measures were postoperative Hb drop and requirement for RBC. The secondary aim was evaluation of risk factors for postoperative RBC transfusions. Results: After application of PSM, 364 patients treated by laparoscopy were matched with 364 patients undergone open surgery. The two groups presented similar clinical and pathological characteristics, as well as comparable postoperative outcomes. 56 patients in the open group and 47 in the laparoscopic group required postoperative RBC (P = 0.395). No difference was observed in terms of mean number of RBC units (P = 0.608) or Hb drop (P = 0.129). Logistic regression analysis identified preoperative anaemia and occurrence of postoperative complications as relevant risk factors for postoperative RBC transfusion, while surgical approach did not prove statistically significant. Conclusion: Laparoscopy did not influence postoperative requirements for RBC transfusions after elective colorectal surgery. Preoperative anaemia and occurrence of postoperative complications represent the major determinants for postoperative transfusions after open as well as laparoscopic surgery