ALMA and Herschel Observations of the Prototype Dusty and Polluted White Dwarf G29-38

ALMA Cycle 0 and Herschel PACS observations are reported for the prototype, nearest, and brightest example of a dusty and polluted white dwarf, G29-38. These long wavelength programs attempted to detect an outlying, parent population of bodies at 1-100 AU, from which originates the disrupted planetesimal debris that is observed within 0.01 AU and which exhibits L_IR/L = 0.039. No associated emission sources were detected in any of the data down to L_IR/L ~ 1e-4, generally ruling out cold dust masses greater than 1e24 - 1e25 g for reasonable grain sizes and properties in orbital regions corresponding to evolved versions of both asteroid and Kuiper belt analogs. Overall, these null detections are consistent with models of long-term collisional evolution in planetesimal disks, and the source regions for the disrupted parent bodies at stars like G29-38 may only be salient in exceptional circumstances, such as a recent instability. A larger sample of polluted white dwarfs, targeted with the full ALMA array, has the potential to unambiguously identify the parent source(s) of their planetary debris.Comment: 8 pages, 5 figures and 1 table. Accepted to MNRA

Crossbreeding of cattle: effects on milk production

International audienc

Aspects of Femininity in French Medieval Bestiaries

his thesis examines the representation of femininity in six French medieval bestiaries (Philippe de Phaon: Bestiaire, Gervaise: Bestiaire, Guillaume de Normandie: Bestiaire divin, Pierre de Beauvais: Bestiaire, Richard de Fournival: Bestiaire d’amour, pseudo-Pierre de Beauvais: Bestiaire) written in the 12th and the 13th centuries. In the Middle Ages the sexual difference was thought to have the essential influence on character and behaviour. Feminine beings were defined in comparison with masculine beings, they were and less valued and represented as inferior. French bestiaries examined in the thesis have the characteristics of medieval didactic literature (which have the sources in the naturalist texts of Antiquity and late Antiquity), religious and courtly tradition. By analysing the topics containing characteristics of femininity in the naturalist parts of the bestiary chapters (maternity, sexual difference, partnership and the representation of an independent feminine individual), we have concluded that the representation of female individuals contains socially constructed gender stereotypes, that the female individual is represented in implicit comparison with the male individual (which has a higher valorisation) and that there is metaphorical usage of femininity as a negative valorisation. The interpretative parts of bestiary chapters of traditional bestiaries (Philippe de Thaon, Gervaise, Guillaume of Normandy, Pierre de Beauvais, pseudo-Pierre de Beauvais) don‟t make a difference between male and female recipients and dont‟t systematically criticize females as inferior beings, however they introduce traditional misogynist characterization of females (lust, greed, duplicity). Eve and Virgin Mary are present as biblical female characters, even though there is no direct relation between them and women. The courtly interpretation of bestiary of Richard de Fournival contains the characterisation of female nature which has the characteristics traditionally attributed to women (talkativeness, duplicity, superficiality, instability). In this bestiary we have found that the nature of ideal love is described through the representation of motherly love towards the young, which we have named the female paradigm of love. The social and historical context of the feudal society can partly be constructed from the bestiaries dedicated to women. We have concluded that at all the levels of the analysis femininity is represented with misogyny, in comparison with masculine identity and less valued, which was a general opinion in the Middle Ages. From this point of view there is no difference between the traditional bestiaries, which interpret the universe symbolically, and the courtly bestiary influenced by Aristotelian naturalism

AC Impedance tracking of glassy carbon activation

Carbon materials, due to their physical and chemical properties, have found wide application in different electrochemical systems. They are often used as substrates for supercapacitors and different types of electrocatalysts. Upon activation, their electrochemical properties are improved. Glassy carbon can be successfully used as a model for studying the process of carbon activation. In this work, the activation of glassy carbon by electrochemical oxidation in sulfuric acid was investigated using cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy. Glassy carbon was oxidized during the same time at 5 different potentials. Cyclic voltammetry shows that the higher the potential the larger the increase in double layer capacitance is. Impedance measurements confirmed significant changes in capacitive response of activated glassy carbon in comparison to unoxidized state. AFM examination of treated GC surfaces revealed morphological changes and increase in roughness upon oxidation. If combined, the results of these studies show that the activation of glassy carbon proceeds through three stages: oxidation of active site, growing of graphite oxide layer and mechanical destruction of the surface.Belgrade, Serbia, June 6-10, 2010Related to the published paper in the Proceedings of the Second Regional Symposium on Electrochemistry South-East Europe, [http://cer.ihtm.bg.ac.rs/handle/123456789/3541

AC Impedance tracking of glassy carbon activation

Carbon materials, due to their physical and chemical properties, have found wide application in different electrochemical systems. They are often used as substrates for supercapacitors and different types of electrocatalysts. Upon activation, their electrochemical properties are improved. Glassy carbon can be successfully used as a model for studying the process of carbon activation. In this work, the activation of glassy carbon by electrochemical oxidation in sulfuric acid was investigated using cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy. Glassy carbon was oxidized during the same time at 5 different potentials. Cyclic voltammetry shows that the higher the potential the larger the increase in double layer capacitance is. Impedance measurements confirmed significant changes in capacitive response of activated glassy carbon in comparison to unoxidized state. AFM examination of treated GC surfaces revealed morphological changes and increase in roughness upon oxidation. If combined, the results of these studies show that the activation of glassy carbon proceeds through three stages: oxidation of active site, growing of graphite oxide layer and mechanical destruction of the surface.Belgrade, Serbia, June 6-10, 2010Related to the published paper in the Proceedings of the Second Regional Symposium on Electrochemistry South-East Europe, [http://cer.ihtm.bg.ac.rs/handle/123456789/3541

Dual responsive hybrid hydrogels for controlled release of local anesthetic

Inteligentni hidrogelovi, kao što su pH osetljivi hidrogelovi na bazi poli(metakrilne kiseline) (PMAA), imaju veliku primenu u ciljanoj dostavi lekova. Međutim, slaba mehanička svojstva često ograničavaju primenu PMAA. Kako bi se prevazišlo navedeno ograničenje, nanoceluloza (NC) je prvo ekstrakovana iz drvnog otpadnog materijala, a zatim dodata u PMAA, zato što je NC biokompatibilna, netoksična i ima odlična mehanička svojstva. Zatim je dodata karboskimetil celuloza (CMC) (celulozni derivat koji se često koristi za kontrolisano otpuštanje lekova). CMC može da stabilizuje nanočestice magnetita (MN) koje su takođe dodate. MN mogu značajno da poboljšaju mehanička svojstva hidrogelova i takođe poseduju magnetna svojstva zbog čega imaju primenu za ciljano otpuštanje lekova. Ovako dobijeni materijal bi mogao da zaštiti lek, dostavi ga do mesta delovanja, kontroliše brzinu njegovog otpuštanja i na taj način omogući efikasno dejstvo leka sa smanjenim neželjenim efektima. Lokalni anestetik – lidokain hidrohlorid (LH) se često u tretmanima injektira što može imati ozbiljne neželjene efekte. Inkapsulacijom LH u hidrogelove na bazi PMAA, NC, CMC i MN (PMNC/MN-L) rešen je navedeni problem. Karakterizacija PMNC/MN-L hidrogelova je izvedena primenom FTIR i SEM spektroskopija i kompresionim testovima, a zatim je analizirano bubrenje hidrogelova i otpuštanje LH. U ovom radu predstavljen je jedinstveni način „zelene” sinteze hibridnih hidrogelova osetljivih na spoljne stimulanse unapređenih svojstava i njihove primene za kontrolisano otpuštanje lokalnog anestetika sa smanjenim neželjnim efektima

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders. Part III. Influence of Particle Morphology on Appearance of Electrical Conductive Layers

The electrical conductivity of the system based on lignocellulose (LC) biopolymer matrix filled with electrodeposited copper powder has been studied. Galvanostatically produced copper powder, having highly porous, highly dendritic particles with high values of specific area was used as filler. Volume fraction of the electrodeposited copper powder was varied from 2.0-29.8 vol%. Analysis of the most significant properties of prepared composites and its components included measurements of electrical conductivity, impedance spectroscopy (IS) behavior, structural and morphological analysis. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume. It was shown that percolation threshold depends on both particle shape and type of spatial distribution. IS measurements have shown that particle morphology having pronounced grain boundaries has great effect on appearance of electric conductive layers, i.e.. movement. of percolation threshold towards lower filler volume fractions. IS response of the composites showed existence of electrical conductive layers, each having different resistivity which increases towards interior of the composite

Warm gas at 50 AU in the disk around Herbig Be star HD 100546

The disk atmosphere is one of the fundamental elements of theoretical models of a protoplanetary disk. However, the direct observation of the warm gas (>> 100 K) at large radius of a disk (>> 10 AU) is challenging, because the line emission from warm gas in a disk is usually dominated by the emission from an inner disk. Our goal is to detect the warm gas in the disk atmosphere well beyond 10 AU from a central star in a nearby disk system of the Herbig Be star HD 100546. We measured the excitation temperature of the vibrational transition of CO at incremental radii of the disk from the central star up to 50 AU, using an adaptive optics system combined with the high-resolution infrared spectrograph CRIRES at the VLT. The observation successfully resolved the line emission with 0".1 angular resolution, which is 10 AU at the distance of HD 100546. Population diagrams were constructed at each location of the disk, and compared with the models calculated taking into account the optical depth effect in LTE condition. The excitation temperature of CO is 400-500 K or higher at 50 AU away from the star, where the blackbody temperature in equilibrium with the stellar radiation drops as low as 90 K. This is unambiguous evidence of a warm disk atmosphere far away from the central star.Comment: 7 pages, 5 figures, A&A in pres

Influence of process parameters of simultaneous anodization/anaphoretic electrodeposition synthesis of hydroxyapatite/titanium oxide composite coatings on adhesion

In-situ synthesis of hydroxyapatite/titanium oxide (HAp/TiO2) coating on titanium was performed via anaphoretic deposition of hydroxyapatite (HAp) and simultaneous anodization of Ti to produce highly adherent and strengthened composite coating. The influence of electric potential, time, electrolyte concentration and pH value of the anodization process on titanium surface roughness and anodization of titanium was examined, as well as influence of same process parameters on adhesion strength and compactness of composite HAp/TiO2 coatings was investigated. Prior to novel in situ method of synthesis of hydroxyapatite/titanium oxide composite coatings by simultaneous anodization/anaphoretic electrodeposition described in this manuscript, optimization of anodization process of titanium was performed. Anodization was executed under different electric potentials and different distances of counter electrodes from working electrodes, but all anodization processes had constant quantity of electric charge. Characterization of titanium samples, prepared from grade 6 Ti, and having rectangular contact surfaces of 10×10×0.89 mm included SEM/EDS analyses, X-ray diffraction analyses, AFM surface topography, morphology and roughness analyses and linear measurements of roughness.A chemical precipitation method was used to prepare hydroxyapatite powder by the reaction of calcium oxide (obtained by calcination of CaCO3 for 5 h at 1000 °C in air) and phosphoric acid. A stoichiometric amount of the calcium oxide was stirred in distilled water and phosphoric acid was added drop wise to the suspension in order to obtain hydroxyapatite powder, Ca10(PO4)6(OH)2.Two types of HAp coatings were prepared, in order to compare the adhesion, morphology and consistency of the HAp and composite HAp/TiO2 on Ti, namely cathaphoretic and anaphoretic coatings, respectively [1,2]. The prepared coatings were characterized by field emission scanning electron microscopy, X-ray diffraction and electron dispersive spectroscopy. Adhesion was investigated by ASTM D 3359 – 97 Test method B. Uniform and adherent HAp/TiO2 composite coating on Ti was obtained. Since smaller size of HAp crystals within highly porous coating structures is of improved binding ability to various biomolecules, our coating is expected to be of excellent coverage and compactness. The obtained coating can be good candidate for bone implants due to improved adhesion