Adsorption of silanes bearing nitrogenated Lewis bases on SiO 2/Si (100) model surfaces

The present paper describes the one-pot procedure for the formation of self-assembled thin films of two silanes on the model oxidized silicon wafer, SiO2/Si. SiO2/Si is a model system for other surfaces, such as glass, quartz, aerosol, and silica gel. MALDI-TOF MS with and without a matrix, XPS, and AFM have confirmed the formation of self-assembled thin films of both 3-imidazolylpropyltrimethoxysilane (3-IPTS) and 4-(N- propyltriethoxysilane-imino)pyridine (4-PTSIP) on the SiO2/Si surface after 30 min. Longer adsorption times lead to the deposition of nonreacted 3-IPTS precursors and the formation of agglomerates on the 3-IPTS monolayer. The formation of 4-PTSIP self-assembled layers on SiO2/Si is also demonstrated. The present results for the flat SiO2/Si surface can lead to a better understanding of the formation of a stationary phase for affinity chromatography as well as transition-metal-supported catalysts on silica and their relationship with surface roughness and ordering. The 3-IPTS and 4-PTSIP modified SiO2/Si wafers can also be envisaged as possible built-on-silicon thin-layer chromatography (TLC) extraction devices for metal determination or N-heterocycle analytes, such as histidine and histamine, with on-spot MALDI-TOF MS detection. © 2005 Elsevier Inc. All rights reserved.

In vitro evaluation of the abrasiveness of a commercial low-abrasive dentifrice and an experimental dentifrice containing vegetable oil

Toothpastes usually contain detergents, humectants, water colorant, fluoride and thickeners (e.g. silica). Tooth wear has a multi-factorial etilology and the use of abrasive dentifrices is related to abrasion of dental tissues during toothbrushing. This study evaluated in vitro the abrasiveness of a commercial silica gel low-abrasive dentrifice compared to an experimental dentifrice containing vegetable (almond) oil. Distilled water served as a control group. Acrylic specimens (8 per group) were submitted to simulated toothbrushing with slurries of the commercial dentifrice experimental dentifrice, almond oil and water in an automatic brushing machine programmed to 30,000 brush strokes for each specimen which is equivalent to 2 years of manual toothbrushing. Thereafter, surface roughness (Ra) of the specimens was analyzed with a Surfcorder SE 1700 profilometer. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no statistically significant differences (p>0.05) in the surface roughness after brushing with water almond oil experimental dentifrice. The commercial dentifrice produced rougher surfaces compared to the control and abrasive free products (p<0.05). Further studies are necessary in confirm the potential benefits of using vegetable oil in toothpaste as an alternative in abrasives in an attempt to minimize the tooth wear caused by toothbrushing.

Identification of ellagic acid derivatives in methanolic extracts from Qualea species

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of drying rate and storage time on Magnolia ovata Spreng. seed viability

Magnolia ovata seeds have been reported as desiccation sensitive. In order to test if the drying rate would affect the assessment of storage behaviour of these seeds, the effect of different drying rates and storage times on the viability was tested. Seeds were dried over activated silica gel (fast drying) or salt solutions for different periods (slow drying) and stored at -20°C. Partial drying transiently increased the final germination and the germination speed index, but further drying resulted in reduction of these parameters. Drying rate affected the final germination and vigour. Seeds that were slow-dried to 0.10 g H 2O ̇ g -1 dw retained high viability when compared with seeds desiccated to the same water content level by the fast drying method, although their vigour was reduced. Only slow-dried seeds could be stored at -20°C for 90 d without reduction of viability. These data suggested that the storage behaviour of seeds of M. ovata seeds should be classified as intermediate.

Produção de xilanases por Aspergillus niger utilizando planejamento experimental: purificação de xilanase

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação de um biorreator rotativo para fermentação em estado sólido

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preparação e caracterização de sílicas mesoporosas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese de aerogéis e xerogéis de sílica com troca de solvente e secagem a pressão ambiente

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Potencialidades eletroanalíticas de complexos binucleares de nitroprussiato de metais de transição suportado em 3-aminopropil sílica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produção, purificação e ação antimicrobiana do extrato fúngico do Trichosporon asahii

Pós-graduação em Microbiologia - IBILCE

Constituintes micromoleculares de Aristolochia melastoma Manso: compostos nitrados

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nutrients distribution in diseased coffee leaf tissue

Knowing the structure and distribution of nutrients in plant tissues can clarify some mechanisms of pathogen attack in plants and plant defense against infection, thus helping management strategies. The aim of this study was verify differences in distribution of mineral nutrients in coffee leaf tissues around foliar lesions of bacterial blight of coffee, blister spot, cercospora leaf, phoma leaf spot and coffee leaf rust. Fragments of leaf tissue surrounding the lesions were dehydrated in silica gel, carbon covered and subjected to X-ray microanalysis (MAX). Thirty-three chemical elements were detected in leaf tissue; however, there was variation in potassium and calcium contents surrounding the lesions. The highest potassium content was found in asymptomatic tissues surrounding the lesions, decreasing toward the transition zone and reaching minimum content in symptomatic tissues. The highest calcium content was found in symptomatic tissues, decreasing toward the transition zone and reaching minimum content in asymptomatic tissues. Therefore, MAX can be used to analyze the composition and distribution of nutrients in plant tissues and, if associated with mineral nutrition, it may help understand host-pathogen relationships and plant disease management.

Síntese e caracterização de híbridos orgânico-inorgânicos luminescentes para aplicação em ensaios biológicos

Pós-graduação em Química - IBILCE

Hidrocarbonetos policíclicos aromáticos (HPAs) em solo: validação de método e avaliação da influência da queima de cana-de -açúcar na região de Araraquara

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação química e biológica do fungo endofítico Schizophyllum commune isolado de Alchornea glandulosa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)