Gemini spectra of 12000K white dwarf stars

We report signal-to-noise ratio SNR ~ 100 optical spectra for four DA white dwarf stars acquired with the GMOS spectrograph of the 8m Gemini north telescope. These stars have 18<g<19 and are around Teff ~ 12000 K, were the hydrogen lines are close to maximum. Our purpose is to test if the effective temperatures and surface gravities derived from the relatively low signal-to-noise ratio ( ~ 21) optical spectra acquired by the Sloan Digital Sky Survey through model atmosphere fitting are trustworthy. Our spectra range from 3800A to 6000A, therefore including H beta to H9. The H8 line was only marginally present in the SDSS spectra, but is crucial to determine the gravity. When we compare the values published by Kleinman et al. (2004) and Eisenstein et al. (2006) with our line-profile (LPT) fits, the average differences are: Delta Teff ~ 320 K, systematically lower in SDSS, and Delta log g ~ 0.24 dex, systematically larger in SDSS. The correlation between gravity and effective temperature can only be broken at wavelengths bluer than 3800 A. The uncertainties in Teff are 60% larger, and in log g larger by a factor of 4, than the Kleinman et al. (2004) and Eisenstein et al. (2006) internal uncertainties.Comment: 11 pages and 8 figure

Magnetoliposomes based on NixCu1-xFe2O4 or NiFe2-yAlyO4 nanocrystals for applications in magnetic separation and classification

Ferrites are a broad class of compounds with general formula MFe2O4, where M stands for a divalent metallic cation. Among these, copper ferrite (CuFe2O4) presents a moderate saturation magnetization, while nickel ferrite (NiFe2O4) holds a large one. Mixed ferrites with composition NixCu1-xFe2O4 were then prepared by coprecipitation method, in order to control the saturation magnetization with the fraction of Ni. Another possibility is the partial substitution of iron atoms with aluminium, as NiAl2O4 nanocrystals show very low saturation magnetization. Thus, ferrites of NiFe2-yAlyO4 composition were also obtained. XRD spectra of the obtained nanoparticles show the spinel-type crystalline phase. Solid magnetoliposomes of the prepared mixed ferrites were obtained, and their bilayer structure was proven by the use lipophilic fluorescence probes.info:eu-repo/semantics/publishedVersio

Interaction of DODAB with neutral phospholipids and cholesterol studied using fluorescence anisotropy

Liposomes composed of cationic lipids and neutral phospholipids have been used as vehicles for cellular delivery of DNA and drug delivery. The aim of this study is to get a better understanding of phospholipid–cationic lipid interactions that is essential for the development of this potential. We have studied the interaction between cationic lipid liposomes primarily composed of dioctadecyldimethylammonium bromide (DODAB) with two different phospholipids, dioleoyl phosphatidylethanolamine (DOPE) and soybean phosphatidylcholine (PC), as well as with cholesterol. The effect of these components on the liposome’s physical properties (microviscosity and polarity) was accessed by studying, both the steady-state and time-resolved, fluorescence anisotropy of the dye Nile Red. This information combined with analysis of the steady-state emission and fluorescence lifetime of Nile Red using the different lipids and cholesterol provided information concerning the polarity and hydration level changes in these vesicle systems along with organisational information

Magnetoliposomes based on magnetite nanoparticles

In this work, magnetic nanoparticles of magnetite were prepared by soft chemical methods, using different surfactants as templating media. These nanoparticles were either covered with a lipid bilayer, forming dry magnetoliposomes, or entrapped in liposomes - aqueous magnetoliposomes.FCT, FEDER, COMPETE/QREN/EU for financial support to CFUM (Strategic Project PEst-C/FIS/UI0607/2011) and to the research project PTDC/QUI/81238/2006 (FCOMP-01-0124-FEDER-007467)

Sucrose in detoxification of coffee plants with glyphosate drift.

The weed control in coffee plants has great importance, as they compete for light, water and nutrients. The chemical control is the most used, emphasizing the glyphosate, however, when applied, drift can occur and consequently cause injuries to coffee. Many farmers use the sucrose application with the objective to reverse the damage caused by the herbicide drift, even without scientific basis to justify such action. The objective of this study was to evaluate the effect of the sucrose application on the detoxification of coffee plants in the implantation phase with glyphosate drift. The experiment was carried out in a greenhouse, using a randomized block design, arranged in a 3 x 3 factorial scheme with 2 additional treatments, using 3 sucrose doses (2, 4 and 8%) with 3 application times (1, 24 and 168 hours after intoxication with 10% of the commercial glyphosate dose) with an additional one in which the plants were not intoxicated and not treated with sucrose and another only with plants intoxicated by glyphosate. After 75 days performing the experiment, growth, physiological and anatomical characteristics were evaluated. The application of sucrose in the reversal of intoxication of growth variables (height, leaf area number of leaves, shoot dry weight and dry weight of the root system) was not efficient. The objective of this study was to evaluate the effect of the sucrose application on the detoxification of coffee plants in the implantation phase with glyphosate drift. For the physiological variables the application of 2% sucrose, one hour after glyphosate intoxication was the most efficient treatment

Plasmonic/magnetic liposomes based on nanoparticles with multicore-shell architecture for chemo/thermotherapy

In this work, multicore magnetic nanoparticles (NPs) of manganese ferrite were prepared using carboxymethyl-dextran and melamine as agglutinating agents.Magnetoliposome-like structures containing the multicore NPs exhibit sizes in the range 250 – 400 nm, being suitable for biomedical applications.FCT under Strategic funding of CF-UM-UP (UIDB/04650/2020

White Dwarf Mass Distribution in the SDSS

We determined masses for the 7167 DA and 507 DB white dwarf stars classified as single and non-magnetic in data release four of the Sloan Digital Sky Survey (SDSS). We obtained revised Teff and log g determinations for the most massive stars by fitting the SDSS optical spectra with a synthetic spectra grid derived from model atmospheres extending to log g=10.0. We also calculate radii from evolutionary models and create volume-corrected mass distributions for our DA and DB samples. The mean mass for the DA stars brighter than g=19 and hotter than Teff=12000K is M(DA)= 0.593+/-0.016M(Sun). For the 150 DBs brighter than g=19 and hotter than Teff=16000K, we find M(DB)=0.711+/-0.009 M(Sun). It appears the mean mass for DB white dwarf stars may be significantly larger than that for DAs. We also report the highest mass white dwarf stars ever found, up to 1.33 M(Sun).Comment: Accepted for publication in the MNRAS, 27 pages, 14 figures and 6 tables. Corrected sky coverage area and densitie

Magnetic liposomes based on nickel ferrite and manganese ferrite nanoparticles for biomedical applications

In this work, nickel ferrite and manganese ferrite nanoparticles were synthesized and characterized. These nanoparticles were incorporated in liposomes for biomedical applications.Fundação para a Ciência e a Tecnologia (FCT

Fluorescence studies on new potential antitumoral 1,3-diarylurea derivatives in the thieno[3,2-b]pyridine series encapsulated in magnetoliposomes

Magnetic nanoparticles of magnetite and of nickel core with silica shell were prepared and either covered with a lipid bilayer or entrapped in liposomes, forming magnetoliposomes. New potential antitumoral 1,3-diarylurea derivatives of thieno[3,2-b]pyridines were then encapsulated in liposomes and magnetoliposomes and their photophysical behavior was investigated.Fundação para a Ciência e a Tecnologia (FCT), FEDER, COMPETE/QREN/EU for financial support to CFUM (PEst-C/FIS/UI0607/2011) and CQ/UM (PEst-C/QUI/UI0686/2011) and to research projects PTDC/QUI/81238/2006 (FCOMP-01-0124-FEDER-007467), PTDC/QUIQUI/111060/2009 (FCOMP-01-0124-FEDER-015603)