Abstract This study investigated the feasibility of synthesizing sodium silicate from rice husk ash (RHA) and its application to produce geopolymers. Samples were prepared at different SiO2/Al2O3 molar ratios (3.0, 3.5, and 4.0) for both sodium silicates (commercial and from RHA). They were underwater cured at 60 ºC for 1 h and then at room temperature (25 ºC in the air) until the time of the tests (7 and 28 days). The results showed that the compressive strength significantly increased along with the SiO2/Al2O3 ratio for both silicates. Geopolymers produced with sodium silicate from RHA showed higher compressive strengths for most studied samples. The highest compressive strength (6.33±0.23 MPa) was obtained for samples with SiO2/Al2O3 ratio of 4.0 at 7 days, representing a 40% increase in average values compared to commercial sodium silicate under the same conditions. XRD data and FTIR spectrum confirmed that it was possible to synthesize a geopolymer with sodium silicate using RHA.

Resumo Este estudo descreve a formação de novas ligações C-C através da reação de alilação de diferentes aldeídos promovida pela zeólita beta. Este método ecologicamente amigável foi caracterizado por sua eficiência, versatilidade e quimiosseletividade, na formação de diferentes álcoois homoalílicos. Os álcoois homoalílicos foram obtidos em bons rendimentos (80% a 96%), tempos reacionais curtos (30 a 75 min) em temperatura ambiente e sem a necessidade de purificações adicionais. Além disso, foi utilizada água como cossolvente garantindo ao método um desenvolvimento no âmbito da química verde. Adicionalmente, constatou-se que a zeólita beta pode ser reutilizada por até um ciclo reacional sem perda de sua eficiência.

Abstract This study describes the formation of new C-C bonds through the allylation reaction of different aldehydes promoted by beta zeolite. This environmentally friendly method was characterized by its efficiency, versatility, and chemoselectivity in the formation of different homoallylic alcohols. Homoallylic alcohols were obtained in good yields (80% to 96%), short reaction times (30 to 75 min) at room temperature, and without the need for additional purifications. In addition, water was used as a co-solvent, ensuring the method a development in the field of green chemistry. Moreover, it was found that the zeolite beta can be reused for up to one reaction cycle without loss of its efficiency.

Resumo O silicato de sódio é a fonte complementar utilizada na reação de geopolimerização. Entretanto, esse reagente é produzido em alta temperatura ou em autoclave a alta pressão, o que gera muito impacto ambiental. Visando a produção de geopolímeros mais ecológicos, produziu-se um silicato de sódio alternativo (ASW) a partir da dissolução da sílica presente na cinza de casca de arroz (CCA). Foram preparados geopolímeros nas razões molares SiO2/Al2O3 de 3,0, 3,5 e 4,0 e com concentrações de NaOH de 8 e 10 M. Os corpos de prova foram submetidos a ensaios de resistência à compressão (7 e 28 dias), FTIR e DRX. O desempenho mecânico dos geopolímeros produzidos com ASW foi semelhante aos produzidos com silicato de sódio comercial. A análise do comportamento mecânico e dos espectros de infravermelho sugeriu que ocorreu maior dissolução da CCA com o aumento da relação molar SiO2/Al2O3 e da concentração do álcali.

Abstract Sodium silicate is a complementary source used in the geopolymerization reaction. However, this reagent is produced at high temperature or in an autoclave at high pressure, which generates a significant environmental impact. Aiming the production of greener geopolymers, an alternative sodium silicate (ASW) from the dissolution of silica present in rice husk ash (RHA) was produced. Geopolymers were prepared at SiO2/Al2O3 molar ratios of 3.0, 3.5, and 4.0, and concentrations of 8 and 10 M NaOH. The specimens were subjected to compressive strength (7 and 28 days), FTIR and XRD tests. The mechanical performance of ASW-produced geopolymers was similar to those made with commercial sodium silicate. Analysis of the mechanical behavior and infrared spectra suggested that there was a greater dissolution of RHA with increasing SiO2/Al2O3 molar ratio and alkali concentration.

Resumo Neste estudo, foram avaliadas as atividades de enzimas antioxidantes, pigmentos fotossintéticos, conteúdo de prolina e carboidratos em Pitcairnia encholirioides sob déficit hídrico em condições ex vitro. Os resultados mostraram que as plantas sob estresse hídrico progressivo, previamente cultivadas in vitro em meio de cultura suplementado com 30 g L-1 de sacarose e GA3 acumularam mais prolina e aumentaram a atividade da peroxidase (POD) e os teores de pigmentos fotossintéticos e carboidratos. Para plantas previamente cultivadas in vitro com 15 g L-1 de sacarose e ANA, não foram encontradas diferenças nos conteúdos de prolina e houve reduções nas atividades da peroxidase (POD), catalase (CAT) e polifenoloxidase (PPO), e no conteúdo de carboidratos, com o progresso do déficit hídrico ex vitro. Após a reidratação, as plantas apresentaram recuperação fisiológica, com atividades enzimáticas e conteúdo de metabólitos semelhantes aos encontrados nos controles não sujeitos à desidratação, independentemente das condições de cultivo in vitro. Estes resultados mostram que P. encholirioides micropropagada tem alta tolerância à desidratação uma vez em condições ex vitro, o que pode garantir a sobrevivência de plantas provenientes da cultura de tecidos quando transferidas para seu ambiente natural, enfatizando a importância desta biotecnologia para a propagação de espécies ameaçadas.

Abstract In this study, the activities of antioxidant enzymes, photosynthetic pigments, proline and carbohydrate contents in Pitcairnia encholirioides under ex vitro conditions of water deficit were evaluated. Results show that plants under progressive water stress, previously in vitro cultured in media supplemented with 30 g L-1 sucrose and GA3, accumulated more proline and increased peroxidase (POD) activity and the contents of photosynthetic pigments and carbohydrates. For plants previously in vitro cultured with 15 g L-1 sucrose and NAA, no differences were found for proline content and there were reductions in activities of peroxidase (POD), catalase (CAT) and poliphenoloxidase (PPO), and in contents of carbohydrates, with progress of ex vitro water deficit. After rehydration, plants showed physiological recovery, with enzymatic activities and contents of metabolites similar to those found in the controls not submitted to dehydration, regardless of the previous in vitro culture conditions. These results show that micropropagated P. encholirioides has high tolerance to dehydration once in ex vitro conditions, which can ensure the survival of plants from tissue culture when transferred to its natural environment, emphasizing the importance of such biotechnology for the propagation of endangered species.

Resumo A síntese do 6-acetil 1,2:3,4-di-O-isopropilideno-α-D-galactopiranose a partir da reação de acetilação do 1,2:3,4-di-O-isopropilideno-α-D-galactopiranose utilizando a argila montmorilonita K10 como promotor é descrita. O protocolo é rápido, eficiente, econômico, livre de solvente e quimiosseletivo. O produto foi obtido em excelente rendimento (95%), curto tempo reacional (7,5 min), em temperatura ambiente e sem a necessidade de purificação adicional. Adicionalmente, essa argila manteve sua atividade catalítica por três ciclos reacionais sem diminuição de eficiência.

Abstract The synthesis of 6-acetyl 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose by the acetylation reaction of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose using the clay montmorillonite K10 as a promoter is described. The protocol is fast, efficient, cost-effective, solvent-free and chemo-selective. The product was obtained in excellent yield (95%), short reaction time (7.5 min), at room temperature without the need of further purification. In addition, this clay maintained its catalytic activity for three reaction cycles without decreasing efficiency.

ResumoHoje em dia a diversidade de materiais disponíveis para uso em engenharia é muito grande, há um aumento de materiais específicos para cada tipo de aplicação. Os geopolímeros têm sido estudados há décadas; são polímeros inorgânicos que podem proporcionar características de cimentação, que surgem como uma nova classe de materiais de alto desempenho, capazes de substituir total ou parcialmente o cimento Portland em várias aplicações. Neste trabalho foi estudada a influência da adição de diatomita em pastas geopoliméricos baseadas em metacaolinita. A utilização de uma nova matéria-prima abundante na natureza e de baixo valor, como a diatomita, é uma outra alternativa como fonte de sílica para produzir geopolímeros. A diatomita foi usada como um aditivo para melhorar algumas propriedades importantes das pastas de cimento com base em geopolímeros. O efeito da adição de diatomita nas propriedades das pastas geopoliméricas foi avaliado por comparação com as propriedades do geopolímero com base em metacaulim. Para analisar os efeitos de concentrações de diatomita em pastas geopoliméricas, foram realizados testes de filtrado, tempo de espessamento e resistência à compressão. Também são apresentados os resultados de difração de raios X e microscopia electrónica de varredura a fim de reunir informação para uma melhor compreensão da microestrutura do cimento geopolimérico. Os resultados mostraram que a adição de diatomita mudou drasticamente microestrutura e propriedades mecânicas de pastas geopoliméricas. Com o aumento na concentração de diatomita o volume do filtrado diminui, independente da temperatura.

AbstractToday, the diversity of available materials for use in engineering is very large, resulting in an increasing of specific materials for each type of application. The geopolymers have been studied for various decades. They are inorganic polymers that can provide cementing characteristics that emerge as a new class of high performance materials, capable of totally or partially replace the Portland cement in various applications. In this work, we studied the influence of the addition of diatomite on geopolymeric pastes based on metakaolin. The use of a new raw material abundant in nature and low value like the diatomite is another alternative as silica source to produce geopolymers. The diatomite is an amorphous silica and in this work it was used as an additive to improve some important properties in cement pastes based in geopolymers. The effect of adding of the diatomite the geopolymeric properties of the slurries was evaluated by comparing them with the properties of the geo-polymer based on metakaolin. To analyze the effects of diatomite concentrations in geopolymeric pastes, filtrate tests were performed, thickening time and compressive strength. Also presents the results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) in order to gather information for a better understanding of the geopolymers cement microstructure. The results showed that the addition of diatomite changed drastically the microstructure and mechanical properties of geopolymer pastes. With the increasing in the concentration of diatomite, the filtrate volume decreases, independent on the temperature.

The red seaweed Galaxaura marginata (Ellis & Solander) Lamouroux, well known by the antibacterial activity of its polar extract and the cytotoxic activity of its oxygenated desmosterol, showed anti-inflammatory action in its apolar fraction. Topical anti-inflammatory activity was observed in samples collected at São Sebastião channel, northern littoral of São Paulo State, Brazil. The apolar extract and its fractions obtained through Thin-Layer Chromatography (TLC) reduced the topical inflammation produced by croton oil in mouse ear. Such data indicated that the apolar extract from the marine red alga G. marginata displayed anti-inflammatory activity (since 1mg/ear extract reduced 95±0.5% inflammation), which could be the result of the synergic activity of the four fractions present in the apolar extract.

We discuss the applications of Nuclear Magnetic Resonance (NMR) to quantum information processing, focusing on the use of quadrupole nuclei for quantum computing. Various examples of experimental implementation of logic gates are given and compared to calculated NMR spectra and their respective density matrices. The technique of Quantum State Tomography for quadrupole nuclei is briefly described, and examples of measured density matrices in a two-qubit I = 3/2 spin system are shown. Experimental results of density matrices representing pseudo-Bell states are given, and an analysis of the entropy of theses states is made. Considering an NMR experiment as a depolarization quantum channel we calculate the entanglement fidelity and discuss the criteria for entanglement in liquid state NMR quantum information. A brief discussion on the perspectives for NMR quantum computing is presented at the end.

In Brazil, where puffer fish are considered poisonous, there are few documented cases on human consumption and consequent poisoning. In this study, toxicity of two puffer fish species from the Brazilian coast was examined. Specimens of Sphoeroides spengleri and Lagocephalus laevigatus were caught in São Sebastião Channel (North coast of São Paulo State, Brazil) between January 1996 and May 1997. Acidic ethanol extracts from muscle and skin plus viscera were tested for mice acute toxicity using the standard method of Kawabata. Polar extracts of S. spengleri showed high toxicity up to 946 MU/g. Extracts from L. laevigatus showed very low levels of toxicity, never exceeding 1.7 MU/g. All extracts from both species blocked amielinic nerve fiber evoked impulses of crustacean legs; this effect reverted on washing similar to the standard tetrodotoxin TTX. The aqueous extract solutions were partially purified using an ionic exchange column (Amberlit GC-50) followed by treatment with activated charcoal (Norit-A). The presence of TTX and their analogs in the semi-purified extracts were confirmed by HPLC and mass spectrometry (MALDI-TOF).

We have already shown the presence of guanidine neurotoxins in calcareous red algae and mussels collected in the São Sebastião channel (State of São Paulo, Brazil). It is known that these neurotoxins comprise more than 25 analogues such as tetrodotoxin (TTX) and derivatives plus the paralytic shellfish toxins (PST) found in a variety of marine, freshwater and amphibious species. Filter feeding animals generally possess large amounts of these neurotoxins. The tunicates are sessil marine animals with a high rate of sea water filtration. The tunics and siphons of 50 specimens of Phallusia nigra were dissected and the visceral organs were immersed in methanol containing acetic acid 0.02 N pH 5.0. The extract was prepared by homogenization, filtration and the methanolic phase was concentrated under reduced pressure and defatted with chloroform. The polar phase was evaporated and the residue dissolved in deionized water for further purification in ionic-exchange resin column (Bio-Gel P-2) and HPLC analysis. The extract showed paralytic effects on mouse assay (26.9 MU/100mg) and on crustacean isolated nerve preparations. The chemical analysis for TTX and PST revealed toxins with retention times similar to gonyautoxins, saxitoxins and TTX. These findings are important to explain future toxin envenoming outbreaks on the Brazilian coast.

Aqueous solutions of the molluscicidal latex of Euphorbia splendens are irritant to the rabbit eye in concentrations higher than 0.35% and to the rabbit skin in concentrations higher than 0.5%. Although this irritant potential does not proclude its use as a molluscicide, special precautions are recommended for hanbdling and application of the product and the hazard of skin tumor-promoting potencial should be carefully investigated before its use for schistosomiasis vector control.