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In previous work, our group discovered a phenomenon in which a mixed polymer-salt or mixed micellar aqueous two-phase system (ATPS) separates into its two constituent phases as it flows within paper. While these ATPSs worked well in their respective studies to concentrate the target biomarker and improve the sensitivity of the lateral-flow immunoassay, different ATPSs can be advantageous for new applications based on factors such as biomarker partitioning or biochemical compatibility between ATPS and sample components. However, since the mechanism of phase separation in porous media is not completely understood, introducing other ATPSs to paper is an unpredictable process that relies on trial and error experiments. This is especially true for polymer-polymer ATPSs in which the characteristics of the two phases appear quite similar. Therefore, our group aimed to develop semiquantitative guidelines for choosing ATPSs that can phase separate in paper. In this work, we evaluated the Washburn equation and its parameters as a potential mathematical framework to describe the flow behavior of polymer-salt and micellar ATPSs in fiberglass paper. We compared bulk phase fluid characteristics and identified the viscosity difference between the phases as a key determinant of the potential for phase separation in paper. We then used this parameter to predict the phase separation capabilities of polyethylene glycol (PEG)-dextran ATPSs in paper and control the composition of the leading and lagging phases. We also, for the first time, successfully demonstrated the phase separation phenomenon in hydrogels, thereby extending its application and potential benefits to an alternative porous medium.

RESUMEN: El diseño del aislamiento es uno de los aspectos más importantes del diseño del transformador, y de él depende en gran medida su calidad y fiabilidad. El aislamiento usado a lo largo de la historia está formado por materiales celulósicos, principalmente papel y cartón, y líquidos dieléctricos, especialmente aceite mineral, que rellenan las cavidades de estos materiales, proporcionando una mayor rigidez dieléctrica. Además, el líquido dieléctrico cumple las funciones de aislar las partes activas del transformador, transferir el calor de los conductores y diagnosticar el estado del equipo. Por estas razones, varios miles de millones de litros de aceite son utilizados en los transformadores de todo el mundo. Sin embargo, debido a la poca biodegradabilidad de los aceites minerales y el agotamiento de las reservas petrolíferas, se ha impulsado desde hace años una búsqueda de un nuevo líquido dieléctrico capaz de sustituir al aceite mineral y cumplir con las exigencias medioambientales. Los fluidos basados en ésteres, naturales y sintéticos, ofrecen varias ventajas comparados con los aceites minerales, como son su mayor biodegradabilidad y punto de inflamación, pero, sin embargo, su mayor viscosidad influye negativamente en los procesos de impregnación y de evacuación del calor. Por eso, es necesario el estudio del proceso de impregnación con líquidos dieléctricos basados en ésteres. El presente Trabajo de Fin de Grado consiste en una simulación computacional del proceso de impregnación de sólidos celulósicos usados en transformadores de potencia con líquidos dieléctricos. La fiabilidad del aislamiento depende en gran medida del proceso de impregnación, que garantiza que no queden cavidades en la celulosa y así evitar descargas parciales. Un paso importante previo a la realización de la simulación es la caracterización de los materiales a utilizar, sólidos celulósicos y aceites dieléctricos. Usando el software de dinámica de fluidos ANSYS Fluent en medios porosos, se pretende realizar una simulación del proceso de impregnación en varios materiales celulósicos (madera fenólica, cartón y pressboard) y con varios aceites dieléctricos (aceite mineral y éster natural) para obtener una primera aproximación del resultado del proceso sin tener que recurrir a métodos experimentales. ABSTRACT: The insulation design is one of the most important aspects of transformer design, and its quality and reliability depend to a large extent on it. The insulation used throughout history consists of cellulosic materials, mainly paper and cardboard, and dielectric liquids, especially mineral oil, which fill the cavities of these materials, providing greater dielectric strength. In addition, the dielectric liquid performs the functions of insulating the active parts of the transformer, transferring heat from the conductors and diagnosing the condition of the equipment. For these reasons, several billion liters of oil are used in transformers around the world. However, due to the poor biodegradability of mineral oils and the depletion of oil reserves, a search for a new dielectric fluid capable of replacing mineral oil and meeting environmental requirements has been underway for years. Ester-based fluids, both natural and synthetic, offer several advantages over mineral oils, such as higher biodegradability and flash point, but their higher viscosity, however, has a negative influence on the impregnation and heat dissipation processes. Therefore, it is necessary to study the impregnation process with ester-based dielectric liquids. This project consists of a computational simulation of the impregnation process of cellulosic solids used in power transformers with dielectric liquids. The reliability of the insulation depends to a large extent on the impregnation process, which ensures that no cavities are left in the cellulose and thus avoids partial discharges. An important step prior to the simulation is the characterization of the materials to be used, cellulosic solids and dielectric oils. Using the ANSYS Fluent fluid dynamics software in porous media, it is intended to perform a simulation of the impregnation process in various cellulosic materials (phenolic wood, cardboard and pressboard) and with various dielectric oils (mineral oil and natural ester) to obtain a first approximation of the result of the process without having to carry out experimental methods. Grado en Ingeniería en Tecnologías Industriales

Significance: Despite the importance of the cell membrane in regulation of drug activity, the influence of drug treatments on its physical properties is still poorly understood. The combination of fluorescence lifetime imaging microscopy (FLIM) with specific viscosity-sensitive fluorescent molecular rotors allows the quantification of membrane viscosity with high spatiotemporal resolution, down to the individual cell organelles. Aim: The aim of our work was to analyze microviscosity of the plasma membrane of living cancer cells during chemotherapy with cisplatin using FLIM and correlate the observed changes with lipid composition and cell’s response to treatment. Approach: FLIM together with viscosity-sensitive boron dipyrromethene-based fluorescent molecular rotor was used to map the fluidity of the cell’s membrane. Chemical analysis of membrane lipid composition was performed with time-of-flight secondary ion mass spectrometry (ToF-SIMS). Results: We detected a significant steady increase in membrane viscosity in viable cancer cells, both in cell monolayers and tumor spheroids, upon prolonged treatment with cisplatin, as well as in cisplatin-adapted cell line. ToF-SIMS revealed correlative changes in lipid profile of cisplatin-treated cells. Conclusions: These results suggest an involvement of membrane viscosity in the cell adaptation to the drug and in the acquisition of drug resistance.

Hypotheses (1) The equilibrium size and characteristics of a radially wicked fluid on porous material such as paper is expected to be dependent on the fluid properties and therefore could serve as a diagnostic tool. (2) The change in wicked stain size between biological fluids is dependent on a change in solid-liquid surface interfacial energy due to protein adsorption. Experiments Sessile droplets of increasing volume of blood, its components, and model fluids were deposited onto paper and the equilibrium stain size after coming to a halt was recorded. The contact angle of fluid droplets on model cellulose surfaces was measured to quantify the effect that blood protein adsorption at the solid-liquid interface has on radially wicked equilibrium size. Finally the significance of droplet evaporation for the time scale of interest was analysed. Findings The final stain area of all fluids tested on paper scales remarkably linearly with droplet volume. Different fluids were compared and the gradient of this linear relation was measured. Model fluids varying in surface tension and viscosity all behave similarly and exhibit a constant gradient. Blood and its components produce smaller stains, demonstrated by lower gradients. The gradient is a function of protein concentration, thus the mechanism of this phenomenon was identified as protein adsorption at the cellulose-liquid interface. The slope of the area/volume relationship for droplets is an important quantitative mechanistic variable.

Electron beam irradiation (EBI) is an alternative treatment for intrinsic viscosity (IV) control in cellulose pulps, but has never been integrated in full bleaching sequences for comparison to conventional methods. Both eucalyptus kraft (EK) paper pulp and beech sulfite (BS) dissolving pulp were subjected to totally chlorine free (TCF) bleaching sequences comprising either EBI, ozone, or both for IV control. Additionally, effects of EBI on hexenuronic acid (HexA) and xylan were investigated. IV was adjusted to 450–500 mL g−1 and properties including carbonyl content, kappa, brightness, alkali-resistance and sugar composition were compared. Pulps produced with EBI had a higher alkali-resistance, uniformity and less cellulose oxidation. However, the degree of bleaching (DoB) was low without the use of ozone. HexA content in a birch pulp was halved by EBI. Isolated xylans were more resistant to irradiation than cellulose with little decrease of molar masses and moderate oxidation.

This work investigates the spreading dynamics of three candidate sol-gel solutions, of ranging viscosities, surface tensions and densities, and compares them with water and two commercial blood substitute products. Droplets were created with different sizes (10 to75μL) and impact velocities (1.4 to 6.0m/s) to strike 176gsm cardstock. Over 2200 droplets were created using the six different fluids and their final dried stain diameter was measured. Droplet spread was plotted using the Scheller and Bousfield correlation and uses effective viscosity as a parameter for non-Newtonian fluids. Comparing the results to an expected whole human blood range validated the spread of the candidate FBS sol-gel material in passive drip bloodstain pattern simulation. These findings complement the practical application of the material as a safe substitute for demonstrating droplet spread under controlled conditions on hard paper surfaces.

Comparative studies of the effects of two commercial enzyme formulations on fiber refining were conducted. Extensive basic characterisation of the enzymes involved, assessment of their hydrolytic activities on different model substrates as well as on different pulps (softwood sulfate, softwood sulfite, hardwood sulfate) were evaluated. Both enzyme formulations showed endoglucanase as well as some xylanase and β-glucosidase activity. In addition, Enzyme A reached a CMC end viscosity of 19.5 mPa compared to 11.1 mPa for Enzyme B. Reducing sugar release almost doubled from 695 μmol mL−1 for hardwood sulfate pulp to 1300 μmol mL−1 for softwood sulfite pulp with Enzyme B under the same conditions. Enzyme A increased the degree of refining even under non-ideal conditions from 23 °SR to up to 50 °SR. Further characterization of hand sheets, made from enzyme pre-treated and refined cellulose fibers with Enzyme A and B, showed that Enzyme A had the best effects leading to hand sheets with increased tensile strength and low air permeability. In summary, the increase in the degree of refining seen for Enzyme A correlated to higher xylanase and β-glucosidase activity and lower endoglucanase activity.

The production processes of the pulp and paper industry often run in campaigns, leading to large variations in the composition of wastewaters and waste sludges. During anaerobic digestion (AD) of these wastes, the viscosity or the production of extracellular polymeric substances (EPS) and soluble microbial products (SMP) may be affected, with the risk of foam formation, inefficient digester mixing or poor sludge dewaterability. The aim of this study was to investigate how viscosity and production of EPS and SMP during long-term AD of pulp and paper mill sludge is affected by changes in organic loading rate (OLR) and hydraulic retention time (HRT). Two mesophilic lab-scale continuous stirred tank reactors (CSTRs) were operated for 800 days (R1 and R2), initially digesting only fibre sludge, then co-digesting fibre sludge and activated sludge. The HRT was lowered, followed by an increase in the OLR. Reactor fluids were sampled once a month for rheological characterization and analysis of EPS and SMP. The production of the protein fraction of SMP was positively correlated to the OLR, implicating reduced effluent qualities at high OLR. EPS formation correlated with the magnesium content, and during sulphate deficiency, the production of EPS and SMP increased. At high levels of EPS and SMP, there was an increase in viscosity of the anaerobic sludges, and dewatering efficiency was reduced. In addition, increased viscosity and/or the production of EPS and SMP were important factors in sludge bulking and foam formation in the CSTRs. Sludge bulking was avoided by more frequent stirring. Electronic supplementary material The online version of this article (10.1007/s00449-019-02224-4) contains supplementary material, which is available to authorized users.

Orientadores: José Vicente Hallak d'Angelo, Vinicius Bohrer Lobosco Gonzaga de Oliveira Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: A polpação Kraft é o processo mais utilizado para extrair celulose para produção de papel, sendo crucial para suprir a demanda crescente por papel. A polpação gera (um subproduto chamado licor negro) um resíduo chamado licor negro. O licor é uma mistura de uma fração orgânica (lignina, polissacarídeos, entre outros) e uma fração inorgânica (principalmente íon contendo sódio e enxofre Na2SO4 e Na2CO3). O licor negro é regenerado na unidade de recuperação, e posteriormente da origem a um novo licor de cozimento. Geralmente a caldeira de recuperação é o maior gargalo deste processo, limitando a produção de celulose com base em sua capacidade de tratar licor negro. Uma alternativa para esse excesso é usar o licor em um processo para recuperar a lignina por meio de precipitação ácida, reduzindo a carga da caldeira, e aumentando a produção de celulose sem alterar a configuração do ciclo da recuperação química. A precipitação ácida da lignina foi estudada extensivamente, e ainda, uma grande parte dos estudos centraram-se em licores negros originados de coníferas e não angiospermas de clima tropical (por exemplo, Eucalyptus grandis) altamente difundida no Brasil. Como a madeira desempenha um papel vital na composição e nas propriedades físicas e químicas do fluido, estudos usando licores de coníferas não se aplicam a licores de madeira tropical. Considerando a importância da composição do licor ao estudar a recuperação da lignina, este estudo concentra-se em determinar a influência dos principais componentes do licor sobre suas propriedades físicas, visando um modelo preditivo para inferir a viscosidade do licor residual (filtrado) após a precipitação ácida da lignina, usando CO2, a partir de outras propriedades de fácil medição, como massa específica, e sólidos totais. Analisou-se as seguintes propriedades de licor: massa específica (25 °C - 80 °C), teor de sólidos totais, pH, viscosidade (25 °C-80 °C), e o impacto dos principais componentes dos licores. As amostras de processo foram coletadas em oito pontos diferentes do processo (lignina Kraft, licor negro diluído original; licor negro acidulado com pH 10,5, 10, 9,5, 9 e 8,5; e o primeiro filtrado da lignina Kraft em pH 8,5). Um método alternativo para medir a lignina Klason foi proposto e os resultados comparados com o do método padrão. Além de analisar os espectros FTIR, e também inferir insights a partir deles. Determinou-se também o coeficiente de extinção da lignina. Os resultados mostraram que o conteúdo inorgânico influencia mais a densidade do que os sólidos totais e a viscosidade, um resultado significativo, especialmente quando se lida com o aumento da concentração de carbonato devido ao uso de CO2. Diferentemente dos inorgânicos, a lignina, pode afetar mais os sólidos totais e a viscosidade. Os componentes inorgânicos e orgânicos afetam as propriedades físicas de forma diferente. Com base na caracterização física e química, e seu impacto na viscosidade, foi proposta uma correlação. A correlação produziu um modelo que explica o comportamento de viscosidade em diversos teores de lignina (140¿408 g/kg de sólidos secos), faixa de temperaturas (25 °C¿80 °C), sólidos totais (26 %¿32 %) e tensão de cisalhamento entre 0 s?1 ¿2000 s1 Abstract: Kraft pulping is the most widespread process used to extract pulp for paper production, being a crucial piece fulfilling the escalating demand for paper. The pulping process generates a waste stream called black liquor. Black liquor is a mixture of an organic fraction (lignin) and an inorganic fraction (primarily Na2SO4 and Na2CO3). Black liquor is recovered into a new cooking liquor in a recovery boiler. Currently, the recovery boiler is the major bottleneck of this process, limiting pulp production based on its capacity to treat black liquor. An alternative to process the excess of black liquor is to use part of this liquor in a process to recover lignin by means of an acid precipitation process, reducing boiler load while increasing pulp production without upgrading the chemical recovery cycle equipment. Lignin recovery by acid precipitation has been studied extensively, and yet, a large part of the studies have focused on black liquors originated from softwoods and not tropical- hardwoods (e.g., Eucalyptus grandis). Once the type of wood plays a vital role in the composition and consequently in the physical and chemical properties of black liquor, studies using softwoods liquors do not apply to tropical-hardwood liquors. Considering the importance of the liquor composition when studying the recovery of lignin. This study is focused not only in determining the influence of the main components of the liquor over its physical properties but also aims a predictive model to infer the viscosity of the residual liquor after lignin acid precipitation, using CO2, from readily measuring properties as density, total solids, and pH. The experiments were carried out by analyzing the following liquor properties: density (25 °C, 50 °C and 80 °C), total solids content, pH, viscosity (25°C, 50 °C and 80 °C), and measure the concentration and impact of the main components of the liquors. The process streams were collected in eight different locations (kraft lignin, original diluted black liquor; acidulated black liquor with pH 10.5, 10, 9.5, 9 and 8.5; and the first filtrate of kraft lignin at pH 8.5). An alternative method to determine Klason lignin was proposed and the results compared with the standard Klason method. Besides analyzing the FTIR spectra, and also drawing insights from it, the extinction coefficient for lignin was determined. The results have shown that the inorganic content influenced more the density than the total solids and viscosity, a significant result, especially when dealing with the rise in carbonate concentration due to the use of CO2. Unlike the inorganics, lignin affected the total solids and viscosity to more than two orders of magnitude. It was observed that inorganic and organic components affect physical properties differently. Based on the physical and chemical characterization, and their impact on viscosity, a correlation was proposed. The correlation yielded a model that explained the viscosity behavior in various lignin contents (140 ¿ 408 g/kg dry solids), temperatures range (25 °C ¿ 80 °C), solid contents (26 % ¿ 32 %) and shear stress between 0 s?1 ¿ 2000 s?1 Mestrado Engenharia Química Mestre em Engenharia Química

Rationale : Saliva as a sample matrix is rapidly gaining interest for disease diagnosis and point-of-care assays because it is easy to collect (non-invasive) and contains many health-related biomarkers. However, saliva poses particular problems relative to more common urine and blood matrices, which includes low analyte concentrations, lack of understanding of biomolecule transportation and inherent viscosity variability in human samples. While several studies have sought to improve assay sensitivity, few have addressed sample viscosity specifically. The goal of this study is to minimize the effect of sample viscosity on paper-based analytical devices (PADs) for the measurement of pH and nitrite in human saliva. Methods : PADs were used to measure salivary pH from 5.0 to 10.0 with a universal indicator consisting of chlorophenol red, phenol red and phenolphthalein. Nitrite determination was performed using the Griess reaction. Artificial saliva with viscosity values between 1.54 and 5.10 mPa∙s was tested on the proposed PAD. To ensure the proposed PADs can be tailored for use in-field analysis, the devices were shipped to Australia and tested with human specimens. Results : Initial experiments showed that viscosity had a significant impact on the calibration curve for nitrite; however, a more consistent curve could be generated when buffer was added after the sample, irrespective of sample viscosity. The linear range for nitrite detection was 0.1 to 2.4 mg/dL using the improved method. The nitrite measurement in artificial saliva also showed a good correlation with the standard spectrophotometry method (p=0.8484, paired sample t-test, n=20). Measured pH values from samples with varying viscosities correlated well with the results from our pH meter. Conclusions : The inherent variation of salivary viscosity that impacts nitrite and pH results can be addressed using a simple washing step on the PAD without the need for complex procedures.

Growing interest in alternative and renewable energy sources has brought increasing attention to the integration of a pulp mill into a forest biorefinery, where other products could be produced in addition to pulp. To achieve this goal, hemicelluloses were extracted, either by steam explosion or by steam treatment, from Eucalyptus globulus wood prior to pulping. The effects of both pre-treatments in the subsequent kraft pulping and paper strength were evaluated. Results showed a similar degree of hemicelluloses extraction with both options (32-67% of pentosans), which increased with the severity of the conditions applied. Although both pre-treatments increased delignification during pulping, steam explosion was significantly better 12.9 kappa number vs 22.6 for similar steam unexploded pulps and 40.7 for control pulp. Finally, similar reductions in paper strength were found regardless of the type of treatment and conditions assayed, which is attributed to the increase of curled and kinked fibers. © 2013 Elsevier Ltd.

We have developed a photoacoustic (PA) sensor using a low-power, continuous- wave laser and a kHz-range microphone. The sensor is simple, flexible, cost-effective, and compatible with commercial optical microscopes. The sensor enables noncontact PA measurements through air, whereas most current existing PA techniques require an acoustic coupling liquid for detection. The PA sensor has three main components: one is the chamber that holds the sample, the second is a resonator column used to amplify the weak PA signals generated within the sample chamber, and the third is a microphone at the end of the resonator column to detect the amplified signals. The chamber size was designed to be 8 mm × 3 mm as the thermal diffusion length and viscous-thermal damping of air at room pressure and temperature are 2 and 1 mm, respectively. We numerically and experimentally examined the effect of the resonator column size on the frequency response of the PA sensor. The quality factor decreased significantly when the sample chamber size was reduced from 4 mm × 3 mm to 2 mm × 3 mm due to thermos-viscous damping of the air. The quality factor decreased by 27%, demonstrating the need for optimal design for the sample chamber and resonator column size. The system exhibited noise equivalent molecular sensitivity (NEM) per unit bandwidth (NEM / √ Δ f ) of ∼19,966 Hz − 1/2 or 33 × 10 − 21 mol or 33 zeptomol, which is an improvement of 2.2 times compared to the previous system design. This PA sensor has the potential for noncontact high-resolution PA imaging of materials without the need for coupling fluids.

We combined conventional inkjet printing technology with flexographic printing to fabricate drug delivery systems with accurate doses and tailored drug release. Riboflavin sodium phosphate (RSP) and propranolol hydrochloride (PH) were used as water-soluble model drugs. Three different paper substrates: A (uncoated woodfree paper), B (triple-coated inkjet paper) and C (double-coated sheet fed offset paper) were used as porous model carriers for drug delivery. Active pharmaceutical ingredient (API) containing solutions were printed onto 1 cm × 1 cm substrate areas using an inkjet printer. The printed APIs were coated with water insoluble polymeric films of different thickness using flexographic printing. All substrates were characterized with respect to wettability, surface roughness, air permeability, and cell toxicity. In addition, content uniformity and release profiles of the produced solid dosage forms before and after coating were studied. The substrates were nontoxic for the human cell line assayed. Substrate B was smoothest and least porous. The properties of substrates B and C were similar, whereas those of substrate A differed significantly from those of B, C. The release kinetics of both printed APIs was slowest from substrate B before and after coating with the water insoluble polymer film, following by substrate C, whereas substrate A showed the fastest release. The release rate decreased with increasing polymer coating film thickness. The printed solid dosage forms showed excellent content uniformity. So, combining the two printing technologies allowed fabricating controlled-release oral dosage forms that are challenging to produce using a single technique. The approach opens up new perspectives in the manufacture of flexible doses and tailored drug-delivery systems.

Two novel cellulase-poor xylanases from Coprinellus disseminatus SH-1 NTCC-1163 (enzyme-A) and SH-2 NTCC-1164 (enzyme-B) produced under solid-state fermentation mitigated kappa number of wheat straw soda-AQ pulps by 24.38 and 27.94% respectively after XE stages. The release of reducing sugars and chromophores was highest for both the enzymes at 10IU/g and reaction time 180min for 55°C at variable consistencies that is, 10% for enzyme-A and 5% for enzyme-B. (A)XECEHH and (B)XECEHH sequences improved brightness by 5.17 and 2.58% respectively at 4.5% chlorine charge. AOX in (A)XECEHH and (B)XECEHH sequences reduced by 56.11 and 55.75% respectively at 4.5% chlorine charge and 68.34 and 67.98% respectively at 2.25% chlorine charge respectively compared to control. Both the enzymes showed improvement in double fold and tear index with a decrease in burst and tensile index. SEM showed peeling, cracking and delamination in fibers due to enzyme treatment thus facilitating the penetration of bleach chemicals.

The feasibility of thermal ink jet printing as a robust process for biosurface engineering was demonstrated. The strategy investigated was to reconstruct a commercial printer and take advantage of its colour management interface. High printing resolution was achieved by formulating bio-inks of viscosity and surface tension similar to those of commercial inks. Protein and enzyme denaturation during thermal ink jet printing was shown to be insignificant. This is because the time spent by the biomolecules in the heating zone of the printer is negligible; in addition, the air and substrate of high heat capacity absorb any residual heat from the droplet. Gradients of trophic/tropic factors can serve as driving force for cell growth or migration for tissue regeneration. Concentration gradients of proteins were printed on scaffolds to show the capability of ink jet printing. The printed proteins did not desorb upon prolonged immersion in aqueous solutions, thus allowing printed scaffold to be used under in vitro and in vivo conditions. Our group portrait was ink jet printed with a protein on paper, illustrating that complex biopatterns can be printed on large area. Finally, patterns of enzymes were ink jet printed within the detection and reaction zones of a paper diagnostic.

Wood shortages, environmental pollution and high energy consumption remain major obstacles hindering the development of today’s pulp and paper industry. Energy-saving and environmental friendly pulping processes are still needed, especially for non-woody materials. In this study, soda-oxygen pulping of bagasse was investigated and a successful soda-oxygen pulping process for bagasse at 100 °C was established. The pulping parameters of choice were under active alkali charge of 23%, maximum cooking temperature 100 °C, time hold at maximum temperature 180 min, initial pressure of oxygen 0.6 MPa, MgSO4 charge 0.5%, and de-pithed bagasse consistency 12%. Properties of the resultant pulp were screened yield 60.9%, Kappa number 14, viscosity 766 dm3/kg, and brightness 63.7% ISO. Similar pulps were also obtained at 110 °C or 105 °C with a cooking time of 90 min. Compared with pulps obtained at higher temperatures (115–125 °C), this pulp had higher screened yield, brightness, and acceptable viscosity, while the delignification degree was moderate. These results indicated that soda-oxygen pulping at 100 °C, the lowest cooking temperature reported so far for soda-oxygen pulping, is a suitable process for making chemical pulp from bagasse. Pulping at lower temperature and using oxygen make it an environmental friendly and energy-saving pulping process.

A simple and low-cost fabrication method for paper-based diagnostic devices (PBDDs) is described in this study. Street-available polymer solutions were screen printed onto filter papers to create hydrophobic patterns for fluidic channels. In order to obtain fully functional hydrophobic patterns for fluids, the original polymer solutions were diluted with butyl acetate to yield a suitable viscosity range between 30-200 cP for complete patterning on paper. Typical pH and glucose tests with color indicators were performed on the screen printed PBDDs. Images of the PBDDs were analyzed by computers to obtain calibration curves for pH between 2 and 12 and glucose concentration ranging from 10-1000 mmol dm(-3). Detection of formaldehyde in acetone was also carried out to show the possibility of using this PBBD for analytical detection with organic solvents. An exemplar PBDD with simultaneous pH and glucose detection was also used to demonstrate the feasibility of applying this technique for realistic diagnostic applications.

Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans CECT 7291 seems to be a good option for the restoration of degraded paper. In this work BC layers are cultivated and purified by two different methods an alkaline treatment when the culture media contains ethanol and a thermal treatment if the media is free from ethanol. The main goal of these tests was the characterization of BC layers measured in terms of tear and burst indexes, optical properties, SEM, X-ray diffraction, FTIR, degree of polymerization, static and dynamic contact angles, and mercury intrusion porosimetry. The BC layers were also evaluated in the same terms after an aging treatment. Results showed that BC has got high crystallinity index, low internal porosity, good mechanical properties and high stability over time, especially when purified by the alkaline treatment. These features make BC an adequate candidate for degraded paper reinforcement. © 2014 Elsevier Ltd.

An enzymatic biobleaching sequence (L VA QPO) using a laccase from Trametes villosa in combination with violuric acid (VA) and then followed by a pressurized hydrogen peroxide treatment (PO) was developed and found to give high bleaching properties and meet dissolving pulp requirements: high brightness, low content of hemicellulose, satisfactory pulp reactivity, no significant cellulose degradation manifested by α-cellulose and HPLC, and brightness stability against moist heat ageing. The incorporation of a laccase–mediator system (LMS) to bleach sulphite pulps can be a good alternative to traditional bleaching processes since thermogravimetric analysis (TGA) showed that the laccase treatment prevented the adverse effect of hydrogen peroxide on fibre surface as observed during a conventional hydrogen peroxide bleaching treatment (PO). Although VA exhibited the best results in terms of bleaching properties, the performance of natural mediators, such as p -coumaric acid and syringaldehyde, was discussed in relation to changes in cellulose surface detected by TGA.

The removal of old glue from paper artworks is of paramount importance for the preservation of its integrity during the restoration process. Wet cleaning is one of the traditional methods, although it may cause damages on artworks. In this work, an advantageous alternative method, based on the use of a rigid hydrogel, for a simple and localized removal of starch paste from paper supports is presented. The use of an appropriate hydrogel allows to overcome many of the problems faced by restorers minimizing damages, through a controlled release of water to the artwork, and a simple and not invasive application and removal. At the same time, the specific and targeted enzyme activity leads to a significant reduction in the application time of the cleaning procedure. In this context, experiments were carried out applying Gellan hydrogel carrying α-amylase enzyme on several paper samples soiled with starch paste. To assess the cleaning efficacy of the proposed hydrogel, we have used a multidisciplinary approach, by means of spectroscopic techniques, scanning electron microscopy, chromatographic analysis, and pH investigations.

The aim of this work was to evaluate the response to biobleaching of steam exploded kraft pulps and to compare the results with the controls. For this end, a laccase-mediator treatment using commercial laccase (Novozyme 51003) and a natural mediator (acetosyringone) were assayed, followed by alkaline extraction and hydrogen peroxide stages. Our approach resulted in exploded biobleached pulps with lower kappa number and improved optical properties compared to controls, even after subjecting pulps to accelerated ageing. Additionally, use of hydrogen peroxide was reduced. The LMS (laccase-mediator system) had a smaller impact on the properties of the bleached pulps and on hydrogen peroxide consumption than the steam explosion process did. © 2010 Elsevier Ltd.

A new model for simulating non-Brownian flexible fibres suspended in a Newtonian fluid has been developed. Special attention has been given to include realistic flow conditions found in the industrial papermaking process in the key features of the model; it is the intention of the author to employ the model in simulations of the forming section of the paper machine in future studies. The model considers inert fibres of various shapes and finite stiffness, interacting with each other through normal, frictional and lubrication forces, and with the surrounding fluid medium through hydrodynamic forces. Fibre-fluid interactions in the non-creeping flow regime are taken into account, and the two-way coupling between the solids and the fluid phase is included by enforcing momentum conservation between phases. The incompressible three-dimensional Navier-Stokes equations are employed to model the motion of the fluid medium. The validity of the model has been tested by comparing simulation results with experimental data from the literature. It was demonstrated that the model predicts the motion of isolated fibres in shear flow over a wide range of fibre flexibilities. It was also shown that the model predicts details of the orientation distribution of multiple straight, rigid fibres in a sheared suspension. Model predictions of the viscosity and first normal stress difference were in good agreement with experimental data found in the literature. Since the model is based solely on first-principles physics, quantitative predictions could be made without any parameter fitting. En ny modell för simulering av rörelserna hos icke-Brownska böjliga fibrer dispergerade i en Newtonsk vätska har utvecklats. Eftersom det är författarens avsikt att modellen skall kunna tillämpas vid simulering av arkformning under de förhållanden som råder i en modern pappersmaskin, har särskilt omsorg givits till att inkludera motsvarande flödesvillkor i modellens giltighetsområde. Modellen hanterar fibrer av varierande form, massa och styvhet, som växelverkar sinsemellan via normal-, friktions- och smörjkrafter. Deras växelverkan med den omgivande vätskan sker via hydrodynamiska krafter vid finita Reynolds-tal. Den så kallade tvåvägskopplingen mellan fibrerna och vätskefasen har tagits i beaktande genom att kräva att rörelsemängden bevaras vid interaktionen mellan faserna. Vidare har Navier-Stokes ekvationer för inkompressibla vätskor använts för att beskriva mediets rörelser. Modellens giltighet har undersökts genom att jämföra resultat från simuleringar med experimentella data från litteraturen. Det har påvisats att modellen förutsäger rörelsen hos ensamma fibrer i ett skjuvflöde, för vitt skilda fiberflexibiliteter. Det visades också att modellen förutsäger detaljer hos fiberorienteringsdistributionen i suspensioner utsatta för skjuvflöde. Det kunde också konstateras att modellens förutsägelser av fibersuspensioners viskositet och första normalspänningsdifferens under skjuvning väl överensstämde med experimentella data i litteraturen. Kvantitativa förutsägelser har kunnat göras utan någon parameteranpassning, då modellen bygger uteslutande på väletablerade fysikaliska samband inom klassisk mekanik och strömningslära.

Fourteen fungal species, namely Aspergillus flavus, A. fumigatus, A. niger, A. ustus, Penicillium islandicum, P. wortmannii, Memnoniella echinata, Cladosporium herbarum, Stachybotrys atra, Chaetomium globosum, Fusarium oxysporum, Torula herbarum, Alternaria alternata and Curvularia uncinata were isolated from different grades of paper. They differ in their distribution on various kinds of paper and also in relative occurrence. While seasonal influence on mycoflora was observed, most of the moulds were capable of growing in all three seasons examined (summer, winter, rainy season). The moulds were cellulolytic in nature and endoglucanase activity was greatest in Aspergillus flavus, A. niger, A. fumigatus, P. wortmannii and P. islandicum.