961 resultados para Er3 ions
Resumo:
In Tbilisi according to the data of the complex monitoring of light ions concentration, radon and sub-micron aerosols the effect of feedback of intensity of ionizing radiation with the light ions content in atmosphere is discovered.
Resumo:
The results of the stationary and expeditionary investigations of the light ions content in surface boundary layer in the urban and ecologically clean locality for different regions of Georgia are represented.
Resumo:
Estudi elaborat a partir duna estada al Stony Brook University al juliol del 2006. El RbTiOPO4 (RTP) monocristall s un material d' ptica no lineal molt rellevant i utilitzat en la tecnologia lser actual, qumicament molt estable i amb unes propietats fsiques molt destacades, entre elles destaquen els alts coeficients electro-ptics i l'alt llindar de dany ptic que presenta. En els ltims anys sest utilitzant tecnolgicament en aplicacions d'ptica no lineal en general i electro-ptiques en particular. En alguns casos ja ha substitut, millorant prestacions, a materials tals com el KTP o el LNB(1). Dopant RTP amb ions lantnids (Ln3+) (2-4), el material es converteix en un material lser auto-doblador de freqncia, combinant les seves propietats no lineals amb les de matriu lser. El RTP genera radiaci de segon harmnic (SHG) a partir dun feix fonamental amb longituds dona inferiors a 990 nm, que s el lmit que presenta el KTP.La determinaci de la ubicaci estructural i lestudi de l'entorn local del ions actius lser s de fonamental importncia per a la correcta interpretaci de les propietats espectroscpiques daquest material. Mesures de difracci de neutrons sobre mostra de pols cristall mostren que els ions Nb5+ i Ln3+ noms substitueixin posicions de Ti4+ (8-9). Estudis molt recents d'EPR (electron paramagnetic resonance) semblen indicar que quan la concentraci d'i Ln3+ es baixa, aquest i presenta la tendncia a substituir l'i alcal present a l'estructura (10).Desprs dels resultats obtinguts en el present treball a partir de la tcnica EXAFS a la installaci sincrot del Brookhaven National Laboratory/State University of New York (Stony Brook) es pot concloure definitivament que els ions Nb subiquen en la posici Ti (1) i que els ions Yb3+ es distribueixen paritariament en les dues posicions del Ti (1 i 2). Aquests resultats aporten una valuosa informaci per a la correcta interpretaci dels espectres, tant dabsorci com demissi, del material i per la avaluaci dels parmetres del seu comportament durant l'acci lser.
Resumo:
Les vidences s'accumulent concernant des problmes de corrosion touchant les prothses col modulaires. Plusieurs tudes rcentes rvlent des taux d'ions mtalliques levs. Le but de cette tude tait de comparer les taux d'ions mtalliques (Co, Cr, Mo, Ti), dans le srum, chez des porteurs de prothses col modulaire, tige monobloc, ainsi que sans implant. Mthodes Nous avons recrut 60 patients, dont 50 porteurs d'une PTH, unilatrale, sans aucun autre implant, non-cimente, avec tte en cramique, minimum 1 anne postopratoire. Quarante avaient une tige SPS (Symbios) (Ti6Al4 V) modulaire (col en CoCr) et 10 une SPS monobloc (non-modulaire). Les cupules taient toutes en alliage de Ti (Ti6Al4 V) avec insert cramique ou PE. Nous avons constitu un groupe tmoin sans aucun implant. Dans le groupe o modulaires O, le col a t choisi en propratoire sur la base d'une planification 3D et assembl sec avant implantation. Nous avons prlev un chantillon srique, un autre sanguin, qui ont t analyss par spectromtrie de masse, permettant une dtermination atomique quantitative. Le rsultat clinique a t estim l'aide du o Oxford Hip Score O. Rsultats Nous avons trouv un Co srique moyen 1,54 Ig L dans le groupe O modulaires O et 0,32 Ig L dans le groupe o monobloc O avec un p < 0,001. Pour le Cr, on a 1,12 Ig L (modulaires) vs 0,60 Ig L (monoblocs) avec un p < 0,001, pour le Ti 31 Ig L (modulaires) vs 22 Ig L (monoblocs) avec p < 0,001 et pour le Mo, 0,96 Ig L (modulaires) vs 0,74 (monoblocs) avec p = 0,254. Deux patients avaient des valeurs de Co suprieures 7 Ig L et 11 taient au-dessus de 1 Ig L, valeur considre comme limite. Les valeurs dans le sang complet taient similaires. Nous n'avons pas trouv de diffrence significative selon les types de col modulaires (longs vs courts et rtro vs normaux). Curieusement, le taux de Cr tait significativement plus lev chez les patients sans aucun implant que chez les porteurs de SPS monobloc, par contre les diffrences n'taient pas significatives pour les autres lments. Conclusion Les taux sriques et sanguins de ions Co, Cr et Ti taient significativement plus levs dans le groupe des patients avec col modulaire, avec 2 valeurs 40 extrmement hautes et plus de la moiti (11 40) anormalement hautes. Bien que ces valeurs soient infrieures celles d'autres tudes, nous avons arrter d'utiliser de tiges cols modulaires, et avons initi un suivi annuel des patients porteurs, similaire celui instaur pour les grosses ttes mtal-mtal.
Resumo:
We have been able to label the excretory system of cercariae and all forms of schistosomula, immature and adult worms with the highly fluorescent dye resorufin. We have shown that the accumulation of the resorufin into the excretory tubules and collecting ducts of the male adult worm depends on the presence of extracellular calcium and phosphate ions. In the adult male worms, praziquantel (PZQ) prevents this accumulation in RPMI medium and disperses resorufin from tubules which have been prelabelled. Female worms and all other developmental stages are much less affected either by the presence of calcium and phosphate ions, or the disruption caused by PZQ. The male can inhibit the excretory system in paired female. Fluorescent PZQ localises in the posterior gut (intestine) region of the male adult worm, but not in the excretory system, except for the anionic carboxy fluorescein derivative of PZQ, which may be excreted by this route. All stages of the parasite can recover from damage by PZQ treatment in vitro. The excretory system is highly sensitive to damage to the surface membrane and may be involved in vesicle movement and damage repair processes. In vivo the adult parasite does not recover from PZQ treatment, but what is inhibiting recovery is unknown, but likely to be related to immune effector molecules.
Resumo:
Degut a la gran demanda tecnolgica, actualment hi ha un gran inters en desenvolupar medis magntics amb entitats ferromagntiques de dimensions nanomtriques. Aquesta demanda promou la investigaci i el desenvolupament de nous materials i processos de fabricaci que permetin controlar duna manera ms precisa les propietats magntiques i estructurals. Entre els mtodes de litografia convencionals (per exemple deposici fsica a travs de mscares, deposici qumica en fase vapor i electrodeposici), recentment sha demostrat que la irradiaci amb ions a travs de mscares prelitografiades, sembla ser un bon mtode per a la fabricaci destructures ferromagntiques de lordre dels nanmetres. Aquesta tcnica pot ser aplicada per aprofitar la transici paramagnticaferromagntica que presenten alguns materials al ser desordenats estructuralment (per exemple FeAl, FePt3, Ni3Sn2). En el treball que es presenta a continuaci sutilitza laliatge Fe60Al40 per a fabricar estructures ferromagntiques embegudes en una matriu paramagntica mitjanant irradiaci amb ions darg a travs duna membrana de polimetil metacrilat (PMMA) prviament litografiada amb feixos delectrons (EBL). La fabricaci daquest sistema t com a objectiu destudiar levoluci de la morfologia i el gruix de PMMA (a partir de SEM i AFM) i del comportament magntic de les estructures fabricades (MFM i MOKE), quan s irradiat consecutivament a diferents energies. Per a completar lestudi shan utilitzat simulacions per a determinar les condicions dirradiaci (TRIM), com per a una millor comprensi dels resultats (simulacions micromagntiques). El contingut de la memria inclou una breu introducci histrica i conceptual sobre el magnetisme. A continuaci sexposen les tcniques necessries per a la fabricaci, preparaci i caracteritzaci de la mostra. Finalment es presenta una discussi dels resultats obtinguts i les conclusions.
Resumo:
En aquest treball de recerca, shan estudiat les dues isoformes de metallotionena CnMT1 i CnMT2 presents en el fong patogen Cryptococcus neoformans. Recentment sha descobert que aquest fong t com a factor de virulncia, els nivells de coure del medi on es troba. Les dues isoformes produdes en medis rics en Zn(II) shan utilitzat per a fer valoracions amb Cu(I) i Cd(II), i sha seguit levoluci dels experiments mitjanant les tcniques DC, UV-vis, i ESI-MS. Sha pogut observar que les dues isoformes tenen preferncia per enllaar Cu(I). Per altra banda tamb sha establert una gran homologia entre les dues seqncies.
Resumo:
The sensitizing action of amorphous silicon nanoclusters on erbium ions in thin silica films has been studied under low-energy (long wavelength) optical excitation. Profound differences in fast visible and infrared emission dynamics have been found with respect to the high-energy (shortwavelength) case. These findings point out to a strong dependence of the energy transfer process on the optical excitation energy. Total inhibition of energy transfer to erbium states higher than thefirst excited state (4I13/2) has been demonstrated for excitation energy below 1.82 eV (excitation wavelength longer than 680 nm). Direct excitation of erbium ions to the first excited state (4I13/2)has been confirmed to be the dominant energy transfer mechanism over the whole spectral range of optical excitation used (540 nm680 nm).
Resumo:
The variation in the emission of Si+ ions from ion-beam-induced oxidized silicon surfaces has been studied. The stoichiometry and the electronic structure of the altered layer has been characterized using x-ray photoelectron spectroscopy (XPS). The XPS analysis of the Si 2p core level indicates the strong presence of suboxide chemical states when bombarding at angles of incidence larger than 30 . Since the surface stoichiometry or degree of oxidation varies with the angle of incidence, the corresponding valence-band structures also differ among each other. A comparison between experimental measurements and theoretically calculated Si and SiO2 valence bands indicates that the valence bands for the altered layers are formed by a combination of those two. Since Si-Si bonds are present in the suboxide molecules, the top of the respective new valence bands are formed by the corresponding 3p-3p Si-like subbands, which extend up to the Si Fermi level. The changes in stoichiometry and electronic structure have been correlated with the emission of Si+ ions from these surfaces. From the results a general model for the Si+ ion emission is proposed combining the resonant tunneling and local-bond-breaking models.
Resumo:
Environmental and occupational exposure to heavy metals such as cadmium, mercury and lead results in severe health hazards including prenatal and developmental defects. The deleterious effects of heavy metal ions have hitherto been attributed to their interactions with specific, particularly susceptible native proteins. Here, we report an as yet undescribed mode of heavy metal toxicity. Cd2+, Hg2+ and Pb2+ proved to inhibit very efficiently the spontaneous refolding of chemically denatured proteins by forming high-affinity multidentate complexes with thiol and other functional groups (IC(50) in the nanomolar range). With similar efficacy, the heavy metal ions inhibited the chaperone-assisted refolding of chemically denatured and heat-denatured proteins. Thus, the toxic effects of heavy metal ions may result as well from their interaction with the more readily accessible functional groups of proteins in nascent and other non-native form. The toxic scope of heavy metals seems to be substantially larger than assumed so far.
Resumo:
The nuclear matrix, a proteinaceous network believed to be a scaffolding structure determining higher-order organization of chromatin, is usually prepared from intact nuclei by a series of extraction steps. In most cell types investigated the nuclear matrix does not spontaneously resist these treatments but must be stabilized before the application of extracting agents. Incubation of isolated nuclei at 37C or 42C in buffers containing Mg++ has been widely employed as stabilizing agent. We have previously demonstrated that heat treatment induces changes in the distribution of three nuclear scaffold proteins in nuclei prepared in the absence of Mg++ ions. We studied whether different concentrations of Mg++ (2.0-5 mM) affect the spatial distribution of nuclear matrix proteins in nuclei isolated from K562 erythroleukemia cells and stabilized by heat at either 37C or 42C. Five proteins were studied, two of which were RNA metabolism-related proteins (a 105-kD component of splicing complexes and an RNP component), one a 126-kD constituent of a class of nuclear bodies, and two were components of the inner matrix network. The localization of proteins was determined by immunofluorescent staining and confocal scanning laser microscope. Mg++ induced significant changes of antigen distribution even at the lowest concentration employed, and these modifications were enhanced in parallel with increase in the concentration of the divalent cation. The different sensitivity to heat stabilization and Mg++ of these nuclear proteins might reflect a different degree of association with the nuclear scaffold and can be closely related to their functional or structural role.
