Este trabalho relata a interação de nanotubos de titanato de sódio (Na-TiNT) com soluções aquosas de ácido benzóico, ácido fenilfosfônico e anilina. Os Na-TiNT foram obtidos através do tratamento hidrotérmico de TiO2 em solução aquosa de NaOH. Os resultados obtidos através de FTIR, XRD, TEM e análise elementar mostraram que a estabilidade química, estrutural e morfológica dos nanotubos está relacionada à natureza química do meio (básico ou ácido) e às condições de tratamento (temperatura e tempo de contato). A fase α-fenilfosfonato de titânio(IV) foi formada a partir da interação dos Na-TiNT com ácido fenilfosfônico; a quantidade da nova fase foi dependente do tempo de contato e sua cristalinidade da temperatura. Porém, TiO2 ou nanotubo de titanato contendo H+ foram obtidos, em função das condições de tratamento, a partir da interação dos Na-TiNT com ácido benzóico. Quando os Na-TiNT interagiram com a anilina nenhuma mudança estrutural, morfológica ou composicional foi observada.

This work reports the interaction of sodium titanate nanotubes (Na-TiNT) with aqueous solutions of benzoic and phenylphosphonic acids and of aniline. The Na-TiNT were obtained from hydrothermal treatment of TiO2 in aqueous NaOH solution. The results obtained from FTIR, XRD, TEM and elemental analyses showed that the chemical, structural and morphological stability of the nanotubes is related to the medium (acidic or basic) and to the treatment conditions (temperature and contact time). A titanium(IV) α-phenylphosphonate phase was obtained from interaction between Na-TiNT and phenylphosphonic acid. The amount and crystallinity of the new phase were dependent of the contact time and temperature, respectively. On the other hand, TiO2 or proton-rich titanate nanotubes were formed, depending on treatment conditions, from interaction between Na-TiNT and benzoic acid. When Na-TiNT interacted with aniline, no chemical, morphological or compositional change was observed.

In order to understand the genetic responses resulting from physiological changes that occur in plants displaying citrus variegated chlorosis (CVC) symptoms, we adopted a strategy of comparing two EST libraries from sweet orange [Citrus sinensis (L.) Osbeck]. One of them was prepared with plants showing typical CVC symptoms caused by Xylella fastidiosa and the other with non-inoculated plants. We obtained 15,944 ESTs by sequencing the two cDNA libraries. Using an in silico hybridization strategy, 37 genes were found to have significant variation at the transcriptional level. Within this subset, 21 were up-regulated and 16 were down-regulated in plants with CVC. The main functional categories of the down-regulated transcripts in plants with CVC were associated with metabolism, protein modification, energy and transport facilitation. The majority of the up-regulated transcripts were associated with metabolism and defense response. Some transcripts associated with adaptation to stress conditions were up-regulated in plants with CVC and could explain why plants remain alive even under severe water and nutritional stress. Others of the up-regulated transcripts are related to defense response suggesting that sweet orange plants activate their defense machinery. The genes associated with stress response might be expressed as part of a secondary response related to physiological alterations caused by the infection.