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La transición hacia el uso del papel para la enseñanza de la escritura en las escuelas elementales públicas en México no fue sencilla. Al finalizar el siglo XIX, se había cuestionado el uso de las pizarras por el riesgo que representaban para la salud, pues muchas veces los estudiantes borraban sus escritos con saliva y el material con el que estaban fabricadas no siempre guardaba las especificaciones necesarias, además el ruido al escribir era insoportable. En cambio, el papel, desde el punto de vista higiénico, pedagógico y estético, fue considerado un material superior frente a la dureza de la pizarra, el brillo de la superficie y la poca precisión que se obtenía en el trazo de las letras. Derivado de este planteamiento, se vislumbró seriamente la posibilidad de la adopción de papel en las escuelas oficiales. Sin embargo, este material era escaso y muy caro. Hacia el cambio de siglo, sólo dos fábricas de papel podían surtir a las escuelas y era necesario que abarataran el precio, que el sistema de distribución garantizara el abastecimiento y que el suministro fuera continuo. Este artículo analiza el inicio del proceso de reconversión de una tecnología para la enseñanza como era la pizarra por el papel. Analizo el gasto que significó y cómo esta modificación fue resultado de una multiplicidad de relaciones sociales, culturales, económicas y políticas que se entrecruzaron para dar una nueva configuración del tiempo, el ruido y los valores establecidos en el salón de clases. The transition to the use of paper in public elementary schools in Mexico was not easy. At the end of the nineteenth century, the use of slates had been questioned due to the health risk they represented since students often erased their writing with saliva and the material with which the slates were made did not always meet the necessary specifications. On the other hand, paper, from a hygienic, pedagogical and aesthetic point of view, was considered a superior material compared to the hardness of the slate, the shine of the surface and the lack of precision obtained in the tracing of the letters. Derived from this approach, the possibility of changing materials in official schools was seriously envisioned. However, the paper represented a very high cost. Only two paper mills could supply the schools and it was necessary to lower the price, and guarantee the supply by enhancing the distribution system. This article analyses the beginning of the conversion process of a technology for learning to write such as the slate for paper. I analyse the expense that it meant for the authorities and families, how the change was the result of a multiplicity of social, cultural, economic and political relations that intersected to give a new configuration of time, noise and established values in the classroom. [ABSTRACT FROM AUTHOR]

An energy study was performed at Pulpa Cuba Paper Mill, located in Sancti Spiritus, where an energy management system was applied according to NC: ISO 50001, in order to assess the energy system by applying energy management systems for energy and water reduction in the paper mill, in which the current steam generation, distribution and consumption system is diagnosed. The proposal of a modified energy scheme with 1 MW Backpressure Steam Turbine Generator and rehabilitation of the original boiler or installing a lower capacity boiler contributes to save financial resources by the concept of water, fuel and electricity. The implementation of four projects will save 3,095,574 CUC / y and an average payback period of about 1 year is expected. [ABSTRACT FROM AUTHOR]

This paper evaluates economically build a new cogeneration plant with clean energy from forest biomass company Norske Skog Bio Bio (NSBB). This is to show that this plant-based forest biomass for electricity generation is a viable option in Chile from the economic and environmental perspective. For this evaluation, we propose an approach that uses “real options theory" based on the application of log-transformed binomial method with six steps. Also, comparing the results obtained with this approach, the results using traditional methods. It is found that for all cases studied, the value yielded by the real options method was higher than estimated by traditional methods. It is concluded that this alternative profitable investment. [ABSTRACT FROM AUTHOR]

This research is a documentary, descriptive study looking for assessment the working time cut, of shift work, in paper mills of Venezuela. Ergonomic, legal and economic analysis of time work arrays and organization were used to evaluate the consequences of such changes. Organization of shift work was studied through a simulated case and documentary evidence, such as collective agreements and work schedules Search concludes that mostly of the impacts in human resources of cutting working time on Venezuelan paper mills is going to be positive for our country because employment expansion, low impact on cost and cut time`s work risk exposure. [ABSTRACT FROM AUTHOR]

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To correlate headng impairment and simultaneous occupational exposure to noise and organic solvents, it was made a cross-sectional research in 140 workers from a paper factory's with more than five years in same factory job. Workers were distributed in three groups as follows: unexposed (n=43), exposed to noise (n=50) and exposed to noise and organic solvents (n=47). Medical examination included audiometry to look for hearing impairment. The risk of hypoacusia was greater in exposed workers than in unexposed ones. Exposure to noise longer than five years was related to Odds Ratio (OR)=11,85 (1,46-66.57) and a hearing impairment prevalence of 22%. Simultaneous occupational exposure to noise and solvents produced OR=14.4 (1.78-77.3) and 25.53% hypoacusia prevalence. For men exposed to noise and solvents, the risk of hearing impairment was 1,22 times greater than for workers exposed to noise only [OR=1.22 (0.43-3.43)]. It was determined that workers simultaneously exposed to noise and solvents had not a greater risk to suffer hearing impairment than those exposed only to noise. [ABSTRACT FROM AUTHOR]

This paper shows the methodology and results of the evaluation of the cleaning system of a Kraft paper mill. This evaluation was made keeping in mind variables of that system such as the pulp stock consistency percentage, ash content, air level in the pulp stock, and differential of pressure through the cleaners, for the analysis of a series of samplings carried out during the production of the different paper grades. On the basis of the results, possible modifications or improvements of the cleaning system were proposed, which will allow a reduction in pulp and water losses, energy consumption, and the amount of air required in the paper machine. [ABSTRACT FROM AUTHOR]

The objective of this work was to verify the potentiality from the pulps to the soda-antraquinona of pine for the production of papers wave, liner and newspaper (blended with trash pulp), using adapted technological outlines of one manufactures of trash pulps. The work was carried out with pine chips coming from the north area of Missions, according to a prosecution indicated by Tucumán paper mill. In the case of liner and wave, the reached yield was of 67 % and the results indicated that the used process (soda-AQ of pine, with impregnation of 25 % of the chips) it is adapted for the obtaining of pulp brown semichemical. The obtained pulp presented a quality more than enough to be used in the production of papers liner, being in the inferior limit of quality for the production of papers wave (130 g/m², RCT 1,56 kN/m, CMT 172 N). with regard to the periodic paper, the pulp with yield of 61 % was refined blended with trash pulp in different proportions and it was whitened with NaClO with an objective target of 70 %ISO. The best mixture was that of 90% of trash pulp and 10 % of pulp pine semichemical. [ABSTRACT FROM AUTHOR]

El artículo informa sobre el descubrimiento de los restos de un molino de papel en la Ciudad de México que data del siglo XVI. El molino, construido en el período colonial por la orden agustina, tuvo incidencia en la aceleración del proceso de evangelización en la Nueva España.