Age and isotopes in bottom sediments from Core VER-99-1-St2, Baikal Lake

A simple, reliable, and efficient method has been elaborated for direct determination of isotopic composition of authigenic uranium in siliceous lacustrine sediments. The method is based on studying kinetics of selective extraction of authigenic uranium from sediments by weak solutions of ammonium hydrocarbonate followed by ICP-MS analysis of nuclides. To estimate contamination of authigenic uranium by terrigenous one contents of 232Th and some other clastogenic elements in the extracts were measured simultaneously. Selectivity of extraction of authigenic uranium from the sediments treated with 1% NH4HCO3 solution appeared to be no worse than 99%. The method was applied to analysis of isotopic composition of authigenic uranium at several key horizons of the earlier dated core from the Baikal Lake. Measurements directly show that 234U/238U values in Baikal water varied depending on climate, which contradicts existing hypotheses. Measured 234U/238U ratios in water of the paleo-Baikal match corresponding values reconstructed from isotopic data for total uranium in the sediments on supposition that U/Th ratio is constant in terrigenous fraction of the sediments. Direct experimental determination of total and authigenic nuclides in sediments enhances potentiality of the method for 234U-230Th dating of non-carbonate lacustrine sediments including those from the Baikal Lake within intervals corresponding to periods of glaciation, when sediments were rich in terrigenous components. Portions of terrigenous and authigenic uranium are well separated and we can study variability of sources of terrigenous matter and refine the earlier model for reconstructing climate humidity in the East Siberia.

Structure and magnetotransport properties of the layered manganites REl.2Srl.8Mn,07(R E = La, Pr, Nd)

We have examined the magnetotransport properties and the structure, by Rietveld refinement of powder X-ray data, of the phases RE(1.2)Sr(1.8)Mn(2)O(7) (RE = La, Pr, Nd). We find that on cooling, La1.2Sr1.8Mn2O7 undergoes a transition to a nearly perfect ferromagnet with 90% magnetization at 1.45 T, as reported by earlier workers, but the Pr and Nd phases show only a small magnetization that grows gradually as the temperature is decreased. There seems to be significant correlation between electrical transport and the Jahn-Teller elongation of the apical Mn-O bonds in these systems. The elongation of the apical Mn-O bonds forces the nine-coordinate rock-salt site to be occupied preferentially by the smaller rare-earth-metal cations. This preferential occupation is reliably obtained from the X-ray refinement. All three title phases show a magnetoresistance ratio of about 4(corresponding to a magnetoresistance, [R(0)-R(H)]/R(0), of about 75%) at a field of 7 T and temperatures around 100 K.

Novel pppGpp binding site at the C-terminal region of the Rel enzyme from Mycobacterium smegmatis

Mycobacterium tuberculosis elicits the stringent response under unfavorable growth conditions, such as those encountered by the pathogen inside the host. The hallmark of this response is production of guanosine tetra-and pentaphosphates, collectively termed (p)ppGpp, which have pleiotropic effects on the bacterial physiology. As the stringent response is connected to survival under stress, it is now being targeted for developing inhibitors against bacterial persistence. The Rel enzyme in mycobacteria has two catalytic domains at its N-terminus that are involved in the synthesis and hydrolysis of (p)ppGpp, respectively. However, the function of the C-terminal region of the protein remained unknown. Here, we have identified a binding site for pppGpp in the C-terminal region of Rel. The binding affinity of pppGpp was quantified by isothermal titration calorimetry. The binding site was determined by crosslinking using the nucleotide analog azido-pppGpp, and examining the crosslink product by mass spectrometry. Additionally, mutations in the Rel protein were created to confirm the site of pppGpp binding by isothermal titration calorimetry. These mutants showed increased pppGpp synthesis and reduced hydrolytic activity. We believe that binding of pppGpp to Rel provides a feedback mechanism that allows the protein to detect and adjust the (p)ppGpp level in the cell. Our work suggests that such sites should also be considered while designing inhibitors to target the stringent response.

洞穴碳酸盐^230Th-^234U-^238U测年初始钍校正的等时线研究

IEECAS SKLLQG

Involvement of Rel/Nuclear Factor-κB Transcription Factors in Keratinocyte Senescence

After a finite doubling number, normal cells become senescent, i.e. nonproliferating and apoptosis resistant. Because Rel/nuclear factor (NF)-κB transcription factors regulate both proliferation and apoptosis, we have investigated their involvement in senescence. cRel overexpression in young normal keratinocytes results in premature senescence, as defined by proliferation blockage, apoptosis resistance, enlargement, and appearance of senescence-associated β-galactosidase (SA-β-Gal) activity. Normal senescent keratinocytes display a greater endogenous Rel/NF-κB DNA binding activity than young cells; inhibiting this activity in presenescent cells decreases the number of cells expressing the SA-β-Gal marker. Normal senescent keratinocytes and cRel-induced premature senescent keratinocytes overexpressed manganese superoxide dismutase (MnSOD), a redox enzyme encoded by a Rel/NF-κB target gene. MnSOD transforms the toxic O2.- into H2O2, whereas catalase and glutathione peroxidase convert H2O2 into H2O. Neither catalase nor glutathione peroxidase is up-regulated during cRel-induced premature senescence or during normal senescence, suggesting that H 2O2 accumulates. Quenching H2O2 by catalase delays the occurrence of both normal and premature cRel-induced senescence. Conversely, adding a nontoxic dose of H2O2 to the culture medium of young normal keratinocytes induces a premature senescence-like state. All these results indicate that Rel/NF-κB factors could take part in the occurrence of senescence by generating an oxidative stress via the induction of MnSOD.

Relé diferencial numérico para proteção de transformadores

Dissertação de Mestrado, Engenharia Elétrica e Eletrónica, Especialização em Sistemas de Energia e Controlo, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Proposta de um algoritmo eficiente para a localização de faltas por relé diferencial numérico para proteção de linhas de transmissão com compensação série controlada por tiristores (TCSC)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

RECUEIL DES ŒUVRES POÉTIQUES de Jehan Molinet. Ms. in-fol. sur papier de 201 f., demi-rel. v. f, tr. r. (Rel. du XVIIIe siècle.)

Complainte (La) de Grece

ALBUM AMICORUM de Jean Durand (1583-1592). In-8 de 2 f. lim. et 380 p., mar. r., comp. de mos. de mar. v., riche dorure à petits fers, tr. dor. et ciselée. (Rel. du XVIe siècle.)

Durand (Jean). Album amicorum (1583-1592)

ALBUM AMICORUM de Jacques Vander Cruis, dit Crucius, d'Anvers (1598-1608). In-8 de 8 f. blancs, 172 f. anciennement chiffr. et 13 f. blancs, v. f., dos orné, tr. marbr. (Anc. rel.)

Ficino (Marsiglio). Livre de la vie saine, Livre de la vie longue, trad. par Jehan Beaufilz (1542, n. s.)

LE || TIERS LIVRE || Des Faicts et Dicts || Heroïques du bon Pantagruel : || Composé par M. Fran. || Rabelais docteur || en Medi- || cine. || Reueu, & corrigé par l'Autheur, sus || la censure antique. || L'Autheur susdict || supplie les Lecteurs beneuoles, soy || reseruer a rire au soixante || & dixhuytiesme || Liure. || A Paris, || De l'imprimerie de Michel Fezandat, au mont || S. Hilaire, a l'hostel d'Albret. || 1552. Il Auec priuilege du Roy. In-8 de 160 f. inexactement chiffr. (le dernier coté 170), 3 f. non chiffr. et 1 f. blanc. — LE || QVART LIVRE || des faicts et || dicts Heroiques du bon || Pantagruel. || Composé par M. François Rabelais || docteur en Medicine. || A Paris, || De l'imprimerie de Michel Fezandat, au mont || S. Hilaire, a l'hostel d'Albret. || 1552. || Auec priuilege du Roy. — [A la fin de la Table :] Acheué d'imprimer le XXVIII. de || Ianuier M.D.LII [1552]. In-8 de 19 f. non chiffr., 144 f. chiffr. et 14 f. non chiffr. — Ensemble 2 vol. in-8, mar. citr., fil., dos ornés, tr. dor. (Anc. rel.). Rothschild 1514 (2)

Rabelais (François). Tiers Livre (1552)

Les variations du taux de change réel influencent-elles l'inégalité des revenus entre zones urbaines et rurales en Algérie?

Rapport de recherche

Une analyse empirique du lien entre le secteur de l'énergie et le taux de change réel des provinces canadiennes.

Rapport de recherche