Medidas tipográficas: un recuento

Breve repaso al desarrollo de la concepción métrica en la tipografía en plomo, alternativa y complemento de la visión habitual en lo que conocemos como 'tipometría'. Se parte de una noción amplia de medida: el factor cuantitativo se dilata con la articulación de relaciones proporcionales e integra la dimensión cualitativa de los sistemas métricos tradicionales. La tipografía se considera bajo presupuestos similares: como sistema articulado de piezas materiales cuyas magnitudes contienen usos y valores específicos, más allá de su simple expresión numérica. Con tales premisas, se revisan fuentes documentales significativas del 'período de la imprenta manual'. Su examen, vinculado a los usos y costumbres de oficio, desvela la distinta aproximación métrica, que puede resumirse en tres fases evolutivas: hermética, intensiva, expansiva como recogen las referencias de los cuerpos tipográficos: adjetivas, sustantivas, numéricas. Se proporciona así un marco para apreciar el cambio de sentido en las medidas tipográficas hasta nuestros días.

Uso de membranas de Nafion para a construção de sensores ópticos para medidas de pH

The behaviour of Nafion® polymeric membranes containing acid-base dyes, bromothymol blue (BB) and methyl violet (MV), were studied aiming at constructing an optical sensor for pH measurement. BB revealed to be inadequate for developing sensing phases due to the electrostatic repulsion between negative groups of their molecules and the negative charge of the sulfonate group of the Nafion®, which causes leaching of the dye from the membrane. On the other hand, MV showed to be suitable due to the presence of positive groups in its structure. The membrane prepared from a methanolic solution whose Nafion®/dye molar ratio was 20 presented the best analytical properties, changing its color from green to violet in the pH range from 0.6 to 3.0. The membrane can be prepared with good reproducibility, presenting durability of ca. 6 months and response time of 22 s, making possible its use for pH determination in flow analysis systems.

Integração de técnicas analíticas e proposta de experimentos para cursos de graduação em análise instrumental: uso de espectrômetro de absorção atômica para medidas de absorção molecular

Simple experiments are proposed for measuring molecular absorption of chromate and dichromate ions using an atomic absorption spectrometer. The experiments can help undergraduate students in instrumental analysis courses understand important aspects involving conceptual and instrumental similarities and differences between frequently used analytical techniques. Hollow cathode lamps were selected with wavelengths in the region of molecular absorption of chromate and dichromate. Calibration curves were obtained and the linear dynamic range was evaluated. Results were compared with those obtained in a molecular absorption spectrometer. The molar absorptivities obtained were also compared.

Transformação de triglicerídeos em combustíveis, materiais poliméricos e insumos químicos: algumas aplicações da catálise na oleoquímica

The use of biomass as raw-material for obtaining chemicals, polymers and fuels is emerging as a clever alternative solution for the increasing energy demand, environmental awareness and petroleum shortage. In this work, some attempts in order to develop catalytic systems suitable for triglyceride transformation into fuels, polymers and intermediates are reviewed.

Montagem de um sistema para medidas galvanostáticas simultâneas em mais de uma célula

The present work deals with the design and construction of an equipment for muti-cell accelerated stability test measurements (AST) of dimensionally stable anodes (DSA). The equipment was built using only components that were available in the laboratory. Measurements of three electrochemical cells can be performed using the developed software. The acquisition time interval and the cut-off potencial can be set by the user. Experimental data for RuO2 electrodes obtained with the built equipment are in agreement with the literature.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1881/04/01 (N16,VOL2)-1881/04/30.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1881/05/01 (N17,VOL2)-1881/05/31.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1880/09/01 (N9,VOL1)-1880/09/30.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1880/06/01 (N6,VOL1)-1880/06/30.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1881/02/01 (VOL2,N14)-1881/02/28.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1880/07/01 (N7,VOL1)-1880/07/31.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1880/04/01 (N4,VOL1)-1880/04/30.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1881/11/01 (N23,VOL2)-1881/11/30.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1881/12/01 (VOL2,N24)-1881/12/31.

Chronique de l'imprimerie : gazette cosmopolite de la typographie et de la lithographie / propriétaire-gérant : Paul Schmidt

1881/02/01 (VOL2)-1881/02/28.