Interaction forces between ink particles, cellulose fibers and mineral fillers as determined by AFM

Journal ArticleRecycling of wastepaper is an important industrial activity for the conservation of our natural resources. Wastepaper is mostly generated from newspaper and office waste (from photocopiers and laser printers) [1]. One important step in wastepaper recycling is the separation of ink from cellulose fibers and fillers. The efficiency of ink separation from wastepaper depends on the type of printing process, the type of ink, and the type of paper. For example, it is relatively easy to separate ink from newspaper waste; whereas, the separation of electrophotographic toners from office waste is more difficult mostly because the ink particles are fused during the printing process [2] and their surface properties change

Magnetic separation for wastepaper recycle mills

Journal ArticleAn alternative approach to the conventional washing and flotation techniques for de-inking of mixed office waste (MOW) is magnetic separation. The use of magnetic de-inking has great potential to improve the efficiency of ink removal due to the magnetic content of toners. It is shown experimentally that the magnetic susceptibility of toners typically found in MOW varies from weakly paramagnetic to ferromagnetic. The magnetic de-inking of MOW in itself is not sufficient to achieve a high quality final product due to variations in the magnetic susceptibility of the toner particles. Nevertheless a combination of magnetic separation with flotation appears to be able to produce a final product of superior quality with 92.7% of the dirt removed. Considering these findings appropriate flowsheet modifications are suggested for improved plant performanc

Surface chemistry of pulping and flotation for mixed office wastepaper

Journal ArticleThe effect of pulping reagents on the de-inking flotation of laser printed wastepaper was investigated with regard to the removal efficiency of toner and mineral filler particles at different pH values. These results show that caustic pulping causes the toner to be released from the fibers as larger particles with a reduced hydrophobicity. On the other hand, neutral pulping not only causes the toner to be released as smaller particles but also increases the simultaneous flotation removal of mineral filler particles

Avaliação de linhagens de arroz de terras altas no cerrado de Rondônia.

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Resposta de arroz de sequeiro à abudação mineral no cerrado de Rondônia.

O presente trabalho teve como objetivo avaliar a resposta da cultura do arroz de sequeiro a diferentes níveis de adubação mineral NPK, na região de cerrado do Estadobitstream/item/79276/1/FOL-6151-0001.pd

Pressure effect in the X-ray intrinsic position resolution in noble gases and mixtures

A study of the gas pressure effect in the position resolution of an interacting X- or gamma-ray photon in a gas medium is performed. The intrinsic position resolution for pure noble gases (Argon and Xenon) and their mixtures with CO2 and CH4 were calculated for several gas pressures (1-10bar) and for photon energies between 5.4 and 60.0 keV, being possible to establish a linear match between the intrinsic position resolution and the inverse of the gas pressure in that energy range. In order to evaluate the quality of the method here described, a comparison between the available experimental data and the calculated one in this work, is done and discussed. In the majority of the cases, a strong agreement is observed

Primavera: arroz precoce 'agulhinha' para os cerrados de Rondonia.

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A dynamic method for charging-up calculations: the case of GEM

The simulation of Micro Pattern Gaseous Detectors (MPGDs) signal response is an important and powerful tool for the design and optimization of such detectors. However, several attempts to simulate exactly the effective charge gain have not been completely successful. Namely, the gain stability over time has not been fully understood. Charging-up of the insulator surfaces have been pointed as one of the responsible for the difference between experimental and Monte Carlo results. This work describes two iterative methods to simulate the charging-up in one MPGD device, the Gas Electron Multiplier (GEM). The first method uses a constant step for avalanches time evolution, very detailed, but slower to compute. The second method uses a dynamic step that improves the computing time. Good agreement between both methods was reached. Despite of comparison with experimental results shows that charging-up plays an important role in detectors operation, should not be the only responsible for the difference between simulated and measured effective gain, but explains the time evolution in the effective gain.Comment: Minor changes in grammatical statements and inclusion of some important information about experimental setup at section "Comparison with experimental results

Seroepidemiology of group A rotavirus in suburban São Paulo, Brazil

Age-specifc patterns of rotavirus infection were investigated using a randomly selected and representative sample of sera from a suburban community of São Paulo, Brazil screened for class-specifc antibodies to group A rotavirus. Age-serology of anti-rotavirus IgG showed primary infection predominant in young infants with a median age of around 18 months consistent with IgM serology suggesting highest rates of recent infection between ages 4 and 48 months. Anti-rotavirus serum IgA prevalence increased gradually with age. Paired samples from infants, collected 1 month apart, indicated high exposure rates with seroconversion occurring in several infants during the reported low transmission season. Between 5 and 10% of adults had elevated IgM levels indicative of recent infection and, potentially, of an important contribution adults may play to rotavirus transmission. Further understanding of the dynamics of rotavirus transmission within populations, at group and serotype level, would benefit the design and monitoring of future immunization programmes

Simulation of gain stability of THGEM gas-avalanche particle detectors

Charging-up processes affecting gain stability in Thick Gas Electron Multipliers (THGEM) were studied with a dedicated simulation toolkit. Integrated with Garfield++, it provides an effective platform for systematic phenomenological studies of charging-up processes in MPGD detectors. We describe the simulation tool and the fine-tuning of the step-size required for the algorithm convergence, in relation to physical parameters. Simulation results of gain stability over time in THGEM detectors are presented, exploring the role of electrode-thickness and applied voltage on its evolution. The results show that the total amount of irradiated charge through electrode's hole needed for reaching gain stabilization is in the range of tens to hundreds of pC, depending on the detector geometry and operational voltage. These results are in agreement with experimental observations presented previously