Diffractive optical devices produced by light-assisted trapping of nanoparticles

© 2015 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibitedOne and two-dimensional diffractive optical devices have been fabricated by light assisted trapping and patterning of nanoparticles. The method is based on the dielectrophoretic forces appearing in the vicinity of a photovoltaic crystal, such as Fe:LiNbO3, during or after illumination. By illumination with the appropriate light distribution, the nanoparticles are organized along patterns designed at will. One- and two-dimensional diffractive components have been achieved on X- and Z-cut Fe:LiNbO3 crystals, with their polar axes parallel and perpendicular to the crystal surface, respectively. Diffraction gratings with periods down to around a few micrometers have been produced using metal (Al, Ag) nanoparticles with radii in the range of 70-100 nm. Moreover, several 2D devices, such as Fresnel zone plates, have been also produced showing the potential of the method. The diffractive particle patterns remain stable when light is removed. A method to transfer the diffractive patterns to other non-photovoltaic substrates, such as silica glass, has been also reportedThis work was supported by Spanish projects MAT2011- 28379-C03 and MAT2014-57704-C0

Optimization of nanopores generated by chemical etching of swift-ion irradiated LiNbO3.

The morphology of the nanopores obtained by chemical etching on ion-beam irradiated LiNbO3 has been investigated for a variety of ions (F, Br, Kr, Cu, Pb), energies (up to 2300 MeV), and stopping powers (up to 35 keV/nm) in the electronic energy loss regime. The role of etching time and etching agent on the pore morphology, diameter, depth, and shape has also been studied. The transversal and depth profiles of the pore have been found to be quite sensitive to both, irradiation and etching parameters. Moreover, two etching regimes with different morphologies and etching rates have been identified

Synergy between pyroelectric and photovoltaic effects for optoelectronic nanoparticle manipulation

© 2019 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.The combined action of the pyroelectric (PY) and photovoltaic (PV) effects, exhibited by z-cut LiNbO3:Fe substrates, has been investigated for particle trapping and patterning applications. The novel hybrid procedure provides new possibilities and versatility to optoelectronic manipulation on LiNbO3 substrates. It has allowed obtaining periodic and arbitrary 2D patterns whose particle density distribution is correlated with the light intensity profile but can be tuned through ΔT according to the relative strength of the PV and PY effects. A relevant result is that the PY and PV contributions compete for a ΔT range of 1-20 °C, very accessible for experiments. Moreover, the synergy of the PY and PV has provided two additional remarkable applications: i) A method to measure the PV field, key magnitude for photovoltaic optoelectronic tweezers. Using this method, the minimum field needed to obtain a particle pattern has been determined, resulting relatively high, E~60 kV/cm, and so, requiring highly doped crystals when only using the PV effect. ii) An strategy combining the PY and PV to get particle patterning in samples inactive for PV trapping when the PV field value is under that thresholdMinisterio de Ciencia, Innovación y Universidades of Spain (MAT2014-57704-C3, MAT2017-83951-R); Universidad Politécnica de Madrid (RR01/2016

Characterisation and development of histopathological lesions in a guinea pig model of Mycobacterium tuberculosis infection

Tuberculosis (TB) remains a very significant infectious disease worldwide. New vaccines and therapies are needed, even more crucially with the increase of multi-drug resistant Mycobacterium tuberculosis strains. Preclinical animal models are very valuable for the development of these new disease control strategies. Guinea pigs are one of the best models of TB, sharing many features with the pathology observed in human TB. Here we describe the development of TB lesions in a guinea pig model of infection. We characterise the granulomatous lesions in four developmental stages (I–IV), using histopathological analysis and immunohistochemical (IHC) techniques to study macrophages, T cells, B cells and granulocytes. The granulomas in the guinea pigs start as aggregations of macrophages and few heterophils, evolving to larger lesions showing central caseous necrosis with mineralisation and abundant acid-fast bacilli, surrounded by a rim of macrophages and lymphocytes in the outer layers of the granuloma. Multinucleated giant cells are very rare and fibrotic capsules are not formed in this animal model

Tropospheric Ozone Assessment Report: Present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation

The Tropospheric Ozone Assessment Report (TOAR) is an activity of the International Global Atmospheric Chemistry Project. This paper is a component of the report, focusing on the present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation. Utilizing the TOAR surface ozone database, several figures present the global distribution and trends of daytime average ozone at 2702 non-urban monitoring sites, highlighting the regions and seasons of the world with the greatest ozone levels. Similarly, ozonesonde and commercial aircraft observations reveal ozone’s distribution throughout the depth of the free troposphere. Long-term surface observations are limited in their global spatial coverage, but data from remote locations indicate that ozone in the 21st century is greater than during the 1970s and 1980s. While some remote sites and many sites in the heavily polluted regions of East Asia show ozone increases since 2000, many others show decreases and there is no clear global pattern for surface ozone changes since 2000. Two new satellite products provide detailed views of ozone in the lower troposphere across East Asia and Europe, revealing the full spatial extent of the spring and summer ozone enhancements across eastern China that cannot be assessed from limited surface observations. Sufficient data are now available (ozonesondes, satellite, aircraft) across the tropics from South America eastwards to the western Pacific Ocean, to indicate a likely tropospheric column ozone increase since the 1990s. The 2014–2016 mean tropospheric ozone burden (TOB) between 60˚N–60˚S from five satellite products is 300 Tg ± 4%. While this agreement is excellent, the products differ in their quantification of TOB trends and further work is required to reconcile the differences. Satellites can now estimate ozone’s global long-wave radiative effect, but evaluation is difficult due to limited in situ observations where the radiative effect is greatest

Influence of APOE Genotype on Alzheimer’s Disease CSF Biomarkers in a Spanish Population

Objectives. To evaluate the association between apolipoprotein E (APOE) genotype and cerebrospinal fluid (CSF) levels of Alzheimer’s disease (AD) biomarkers and to study the influence of APOE genotype on the development of AD in a Spanish population. Material and Methods. The study comprised 29 amnestic mild cognitive impairment (MCI) patients and 27 control subjects. Using ELISA methodology, CSF biomarkers and tau/Aβ ratios were obtained. ANOVA and adjusted odds ratios were calculated. Results. We observed the effect of APOE genotype and age on CSF AD variables. The progression to AD was more clearly influenced by CSF AD variables than by age or APOE status. Conclusions. APOE status influences CSF AD variables. However, the presence of APOE ε4 does not appear to be a deterministic factor for the development of AD, because CSF variables have a greater influence on progression to the disease. These results confirm previous observations and, to our knowledge, are the first published in a Spanish population

Ionoluminescence as sensor of structural disorder in crystalline SiO 2: Determination of amorphization threshold by swift heavy ions

Ionoluminescence (IL) has been used in this work as a sensitive tool to probe the microscopic electronic processes and structural changes produced on quartz by the irradiation with swift heavy ions. The IL yields have been measured as a function of irradiation fluence and electronic stopping power. The results are consistent with the assignment of the 2.7 eV (460 nm) band to the recombination of self-trapped excitons at the damaged regions in the irradiated material. Moreover, it was possible to determine the threshold for amorphization by a single ion impact, as ˜1.7 keV/nm, which agrees well with the results of previous studies. © 2012 The Japan Society of Applied Physics.Peer Reviewe