1,052 research outputs found
Photometric brown-dwarf classification. II. A homogeneous sample of 1361 L and T dwarfs brighter than J = 17.5 with accurate spectral types
We present a homogeneous sample of 1361 L and T dwarfs brighter than J = 17.5
(of which 998 are new), from an effective area of 3070 deg2, classified by the
photo-type method to an accuracy of one spectral sub-type using izYJHKW1W2
photometry from SDSS+UKIDSS+WISE. Other than a small bias in the early L types,
the sample is shown to be effectively complete to the magnitude limit, for all
spectral types L0 to T8. The nature of the bias is an incompleteness estimated
at 3% because peculiar blue L dwarfs of type L4 and earlier are classified late
M. There is a corresponding overcompleteness because peculiar red (likely
young) late M dwarfs are classified early L. Contamination of the sample is
confirmed to be small: so far spectroscopy has been obtained for 19 sources in
the catalogue and all are confirmed to be ultracool dwarfs. We provide
coordinates and izYJHKW1W2 photometry of all sources. We identify an apparent
discontinuity, m 0.4 mag., in the Y-K colour between spectral
types L7 and L8. We present near-infrared spectra of nine sources identified by
photo-type as peculiar, including a new low-gravity source ULAS
J005505.68+013436.0, with spectroscopic classification L2{}. We provide
revised izYJHKW1W2 template colours for late M dwarfs, types M7 to M9.Comment: Accepted for publication in A & A, 17 pages, 14 figures, catalogue of
L and T dwarfs supplied here in source files (anc/ directory), and available
on CD
Application of the Modified Murakami’s Anisotropic Creep-Damage Model to 3D Rotationally-Symmetric Problem
This paper demonstrates a modification of the creep-damage equations, proposed by Murakami, Kawai and Rang (MKR). The goals of analysis are: verification of the MKR creep-damage equations and checking the validity of the Reissner theory in the case of a very thick structure of copper under creep-damage conditions
Optimal Design of Rotationally-Symmetric Disks in Thermo-Damage Coupling Conditions
 
EPR investigations of model neuromelanins
The aim of this work was to compare free radical properties of some model neuromelanins obtained from dopamine and its mixture with 5-S-cysteinyldopamine in various molar ratios. The EPR method was used in these investigations; the samples were detected at X and K bands. The parameters of EPR spectra, free radicals concentrations in air and in vacuum, the influence of microwave power and temperature on intensity of resonance signals were measured
Synthesis and Properties of High Tilted Antiferroelectric Esters with Partially Fluorinated Alkoxyalkoxy Terminal Chains
Novel chiral esters with partially fluorinated alkoxyalkoxy terminal chains are described. Their phase transition temperatures, enthalpies, and electrooptical properties are reported. A helical pitch in pure compounds and their mixtures based on selective reflection of light is also characterized
Photo-oxidative action in cervix carcinoma cells induced by HpD — mediated photodynamic therapy
Photodynamic therapy leads to oxidative stress through the generation of free radicals. Oxidative stress causes damage to cellular macromolecules such as nucleic acids, proteins and lipids. Aim: To examine the hematoporphyrin derivative (HpD) — mediated photodynamic effect on cervical adenocarcinoma cell line HeLa. Methods: The HpD localization in HeLa cells was analyzed by confocal microscopy with epi-fluorescence system. Lipid peroxidation (LPO) was estimated by measurement of the concentration of malondialdehyde, protein degradation — by modified Ellman’s method, superoxide dysmutase (SOD) — using Ransod Kit. The expression of inducible nitric oxide synthase (iNOS) was detected by immunocytochemical staining. Results: The HpD was distributed all over the cytoplasm with preferential localization in the inner side of the plasma membrane and around the nuclear envelope. The process of photosensitizer distribution was time dependent. PDT-HpD increased the level of malonodialdehyde (MDA), SOD activity and the expression of iNOS in HeLa cells. However, PDT induced the decrease in the level of protein-associated thiol groups. Conclusions: Our study showed the important role of PDT-mediated oxidative stress in HeLa cells. HpD-PDT might be alternative and less invasive approach for treatment of patients with cervical cancer resistant for standard chemotherapy and radiotherapy
Photometric brown-dwarf classification. I. A method to identify and accurately classify large samples of brown dwarfs without spectroscopy
Aims. We present a method, named photo-type, to identify and accurately
classify L and T dwarfs onto the standard spectral classification system using
photometry alone. This enables the creation of large and deep homogeneous
samples of these objects efficiently, without the need for spectroscopy.
Methods. We created a catalogue of point sources with photometry in 8 bands,
ranging from 0.75 to 4.6 microns, selected from an area of 3344 deg^2, by
combining SDSS, UKIDSS LAS, and WISE data. Sources with 13.0 < J < 17.5, and Y
- J > 0.8, were then classified by comparison against template colours of
quasars, stars, and brown dwarfs. The L and T templates, spectral types L0 to
T8, were created by identifying previously known sources with spectroscopic
classifications, and fitting polynomial relations between colour and spectral
type. Results. Of the 192 known L and T dwarfs with reliable photometry in the
surveyed area and magnitude range, 189 are recovered by our selection and
classification method. We have quantified the accuracy of the classification
method both externally, with spectroscopy, and internally, by creating
synthetic catalogues and accounting for the uncertainties. We find that,
brighter than J = 17.5, photo-type classifications are accurate to one spectral
sub-type, and are therefore competitive with spectroscopic classifications. The
resultant catalogue of 1157 L and T dwarfs will be presented in a companion
paper.Comment: 15 pages, 12 figures, Accepted for publication in A &
Extraction of emerging contaminants from environmental waters and urine by dispersive liquid-liquid microextraction with solidification of the floating organic droplet using fenchol:acetic acid deep eutectic mixtures
In this work, several eutectic mixtures formed by fenchol and acetic acid at seven molar ratios (between 4:1 and 1:4) were characterized and studied for the first time for their possible application as extraction solvents in dispersive liquid-liquid microextraction based on the solidification of the floating organic droplet (DLLME-SFO). A group of 13 emerging contaminants (gemfibrozil, bisphenol F, bisphenol A, 17β-estradiol, testosterone, estrone, levonorgestrel, 4-tert-octylphenol, butyl benzyl phthalate, dibutyl phthalate, 4-octylphenol, 4-nonylphenol, and dihexyl phthalate) was selected and determined by liquid chromatography with ultraviolet and tandem mass spectrometry detection. Among the studied mixtures, only those of 2:1 and 1:1 provided the suitable features from an operational and repeatability point of view, suggesting that several eutectic mixtures of the same components may also provide similar results. Once the extraction conditions of both mixtures were optimized, the method was applied to the extraction of sea water, urine, and wastewater at different concentration levels, allowing the achievement of absolute recovery values between 49 and 100% for most analytes with relative standard deviation values below 19%. In addition, several samples of each type were analyzed, finding bisphenol A and gemfibrozil in some of them. The greenness of the method was also evaluated using the AGREEprep metric. The DLLME-SFO procedure was found to be very simple, quick, and effective and with a good sample throughput
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