8 research outputs found
Electronic Structure and Optical Properties of the Co-doped Anatase TiO Studied from First Principles
The Co-doped anatase TiO, a recently discovered room-temperature
ferromagnetic insulator, has been studied by the first-principles calculations
in the pseudo-potential plane-wave formalism within the local-spin-density
approximation (LSDA), supplemented by the full-potential linear augmented plane
wave (FP-LAPW) method. Emphasis is placed on the dependence of its electronic
structures and linear optical properties on the Co-doping concentration and
oxygen vacancy in the system in order to pursue the origin of its
ferromagnetism. In the case of substitutional doping of Co for Ti, our
calculated results are well consistent with the experimental data, showing that
Co is in its low spin state. Also, it is shown that the oxygen vacancy enhances
the ferromagnetism and has larger effect on both the electronic structure and
optical properties than the Co-doping concentration only.Comment: 12 pages, 4 figure
A scoping review of family experience and need during end of life care in intensive care
Nitrate levels and stages of growth in hypernodulating mutants of Lupinus albus. II. Enzymatic activity and transport of N in the xylem sap Diferentes níveis de nitrato e estágio de crescimento em mutantes hipernodulantes de Lupinus albus II. Atividade enzimática e transporte de N na seiva do xilema
The enzymatic study and transport of N in the xylem sap was carried out with a view to observing the influence of different nitrate levels and growth stages of the plant in chemically treated mutants of Lupinus albus. Several stresses induce a reduction in plant growth, resulting in the accumulation of free amino acids, amides or ureides, not only in the shoot, but also in the roots and nodules. Although enzyme activity is decisive in avoiding products that inhibit nitrogenase by ammonium, little is known about the mechanism by which the xylem carries these products. However, this process may be the key to the function of avoiding the accumulation of amino acids in the cells of infected nodules. The behaviour of the enzymes nitrate reductase (NR), phosphoenolpyruvate carboxylase (PEPC), glutamine synthetase (GS) and nitrogen compounds derived from fixation, such as N-<FONT FACE="Symbol">a</font>-amino, N-ureides and N-amide in mutant genotypes were observed. The NR enzyme activity was highly influenced by the application of nitrate showing much higher values than those in the non-application of nitrate, independently of genotype, being that the NR, the best evaluation period was in the tenth week. The L-62 genotype characterized with nitrate- resistance, clearly showed that the enzyme PEPC is inhibited by presence of nitrate. The L-135 genotype (nod- fix-) showed GS activity extremely low, thus demonstrating that GS is an enzyme highly correlated with fixation. With regard to the best growth stage for GS, Lupinus albus should be evaluated in the seventh week.<br>O estudo enzimático e o transporte de N na seiva do xilema foi realizado visando observar a influência de diferentes níveis de nitrato e estágios de crescimento da planta em mutantes tratadas quimicamente. Vários estresses induzem a redução no crescimento da planta da qual resulta na acumulação de aminoácidos livres, amidas ou ureídos, tanto na parte aérea como nas raízes e nódulos. A atividade de enzimas é decisiva em evitar produtos inibidores da nitrogenase pelo amônio, porém poucas são as informações deste mecanismo com o qual o xilema carrega estes produtos, em compensação, este processo, pode ser a chave da função em evitar acumulação de aminoácidos nas células dos nódulos infectados. O comportamento das enzimas nitrato redutase (NR), fosfoenolpiruvato carboxilase (PEPC), glutamina sintetase (GS) e dos compostos nitrogenados derivados da fixação como: N-<FONT FACE="Symbol">a</font>-amino, N-ureídos e N-amida em genótipos mutados foi observado. A atividade da enzima nitrato redutase foi altamente inflenciada pela aplicação de nitrato apresentando valores bastante superiores em relação a não aplicação do nitrato, independentemente dos genótipos, sendo que o melhor período de avaliação foi na décima semana. O genótipo L-62, com caracteríticas de resistência ao nitrato, mostrou de forma bem evidenciada que a enzima PEPC é inibida pela presença de nitrato. O genótipo L-135 (nod- fix-) apresentou atividade da GS extremamente baixo, mostrando desta forma que a GS é uma enzima altamente correlacionada com a fixação. Em relação ao melhor estágio de crescimento para a GS, o Lupinus albus, deve ser avaliado na sétima semana