Cellulosic fines: Properties and effects

Any cellulosic pulp consists of particles of different dimensions. When trying to understand and control its properties, it is important to consider not only the bulk amount of long fibres, but also the material known as ‘fines’, which may comprise between 1 and 40% of a pulp. These fines have a great impact on the behaviour of pulp, on its processing, and on the characteristics of the resulting products. We compiled a review of research efforts to characterise the fines fraction by origin, morphology, and chemical composition, and to evaluate the fines’ effects especially in papermaking. The main feature of fines is the large specific surface area associated with their size. Their chemical constitution, particularly their charge, and the magnitude of their surface are the basis for their interactions with other pulp components such as extractives, fillers, and retention aids. The surface of fines affects drainage, as well as sheet density and strength. Several optical paper properties are influenced by the morphology of fines and by their chemical composition, which deviates from that of the long fibre fractions. The targeted utilisation of fines is a potential control variable in papermaking applications in order to obtain desirable paper properties.     

Optimized laser processing of calibration blocks for grinding burn detection with Barkhausen noise

Calibration samples for the Barkhausen noise (BN) method were produced with laser processing. A planet gear wheel used for production quality control was subjected to laser irradiation to verify the BN sensor output. Different samples were found to respond similarly to the laser processing although the laser parameters needed to be adjusted for different surface qualities separately. The surface optimization for laser processing was studied with different surface qualities of samples. The ground surface was compared with a sandblasted and vibratory ground surface. The ground and sandblasted surfaces were both amenable to the laser processing whereas the vibratory grinding process created inhomogeneous surfaces for laser beam absorption. Laser processing was found to produce uniform changes in the residual stress values in two perpendicular measuring directions. The root mean square value of the BN voltage signal exhibited linear correlations with the values of the residual stress and surface hardness.     

Design of a low-density wood-cement particleboard for interior wall finish

Gypsum boards form a very large part of the building walls and ceilings finishing market. However, they have poor screw-withdrawal resistance, low hardness and are highly sensitive to moisture. The objective of this study was to determine whether it is possible to make wood-cement particleboards of the same density as gypsum boards while avoiding these drawbacks.Wood-cement particleboards were made by pouring the wood-cement paste in a mould. This was made possible by adding a viscosity modifying mixture to the mixing water and a set accelerating mixture to improve wood/cement compatibility. The mechanical properties and surface quality of the wood-cement particleboards were improved by using, on the board surfaces, paper sheets that were the same as those used on gypsum boards.The average specific gravity of the wood-cement particleboards was the same as gypsum boards, at 0.7. The average bending modulus of rupture obtained for the wood-cement particleboards was 10 MPa in the finishing paper principal direction and 5 MPa in the other direction compared to 5.5 MPa and 1.6 MPa respectively for gypsum boards. The average screw-withdrawal resistance of wood-cement particleboards was 570 N, that is, 1.7 times higher than for gypsum boards.     

Psychometric validation of the Generalized Problematic Internet Use Scale 2 in a Portuguese sample

The Generalized Problematic Internet Use Scale 2 (GPIUS2) assesses individuals’ generalized problematic Internet use (PIU) cognitions, behaviors, and negative outcomes. To date, the GPIUS2 has only been validated in English, Spanish, German, and Italian language. Therefore, the aim of this study was to validate a Portuguese version of the GPIUS2 and provide a taxonomy of the potential risk of PIU among participants. A sample of 641 Portuguese-speaking Internet users was recruited online after a process of translation and back-translation of the original GPIUS2. In-depth validity and reliability analyses were conducted alongside latent profile analysis (LPA) to identify the potential risk of PIU of participants. The validity and reliability analyses revealed adequate results concerning the psychometric properties of the Portuguese GPIUS2. According to the LPA results, participants were classed as “low risk” (n = 289, 46.7%), “medium risk” (n = 256, 40.7%), and “high risk” (n = 77, 12.6%) of PIU with key differences emerging among the three classes. The present findings support the overall validity and usefulness of the Portuguese GPIUS2 and the results from the LPA may be potentially useful in informing practitioners currently working with clients struggling with PIU.     

Preparation of ractopamine-tetraphenylborate complexed nanoparticles used as sensors to rapidly determine ractopamine residues in pork

In this work, we reported a simple, fast, and sensitive determination of ractopamine (RAC) residues in pork by using novel ractopamine-tetraphenylborate complexed nanoparticles (RT NPs) as sensors. The prepared RT NPs exhibited a fast response time of 10 s, a wide linear range from 0.1 to 1.0 × 10⁻⁷ mol/L, and a very low detection limit of 7.4 × 10⁻⁸ mol/L. The prepared sensor also presents a high selectivity for ractopamine under different pH conditions ranged from 2.85 to 7.18. These results reveal that the fabricated RT NPs can be used as efficient electrochemical sensors to determine ractopamine in animal productions.     

Dissolving grade eco-clean cellulose pulps by integrated fractionation of cardoon (Cynara cardunculus L.) stalk biomass

A biorefinery scheme with separate processing of the two main carbohydrate streams (cellulose and hemicellulose-derived) was employed to the energy crop cardoon (Cynara cardunculus L.) to fractionate the whole stalk material. A high quality xylose-enriched substrate was obtained after selective one-step dilute sulfuric acid hydrolysis of hemicelluloses, yielding 18.1 g of xylose per 100 g of dry biomass. The xylan-free solid residue was delignified by sulfur-free organosolv pulping to produce dissolving grade pulps having 93.8% of α-cellulose (33.1 g per 100 g dry initial biomass) and 79.5% degree of crystallinity. About 76% of crop lignin (13.8 g per 100 g dry initial biomass) was recovered from the spent pulping liquor as a high purity reactive precipitated organosolv lignin. Response surface methodology was used for statistical modeling and optimization of the applied separation processes. The central composite rotatable design was applied to assess the effects of the principal technological parameters on the main reaction outputs.     

Alloying and surface composition of model Pd–Ag films synthesized by electroless deposition

PdAg model films and real composite membranes were prepared by sequential electroless deposition on top of porous stainless steel supports. Their surface properties were investigated by X-ray photoelectron spectroscopy (XPS), Angle resolved XPS and sputtering depth profile. It was shown that the surface of the alloy was strongly enriched in silver after the annealing treatment up to 500 °C on hydrogen stream. A relationship between the Ag 3d_5/2 core-level binding energy shift and the silver surface composition was observed from the XPS data obtained with the model samples. The surface composition of real membranes after both hydrogen permeation and reaction experiments showed silver enrichment, in agreement with the data obtained from the model sample.     

6063牌号铝合金内控标样研制及应用

本文从试验、定值及数据处理、有效性验证等几个方面详细阐述了6063牌号内控标样的研制及验证。该方法符合生产要求,大大降低成本,效果良好,可以推广应用。     

廊坊市混凝土实体回弹法测强曲线分析与验证

对廊坊地区的实体结构混凝土构件采用回弹法测强,利用获取的多组平均回弹值、碳化深度值和芯样抗压强度值等数据进行回归分析得到廊坊地区回弹测强曲线,该曲线能真正反映廊坊市结构实体的混凝土强度,为混凝土结构检测验收打下坚实的基础。     

Estimating the value of energy saving in industry by different cost allocation methods

In complicated systems, such as a highly integrated industrial plant with its own energy production, estimating the value of energy conservation is not so straightforward. Often, heat is priced using different kinds of methods for allocating the fuel cost to heat and electricity. However, there is no consistent way to valuate the process steam in industry, and not just one useful method for allocating costs to heat and power. In this paper, the energy method, exergy method, benefit distribution method and market‐based method are evaluated and compared from different decision‐making perspectives. The results of this study indicate that the allocation methods may overestimate by up to 200–300% the benefits from the mill perspective compared to the benefits from the mill site perspective. So, the most suitable method may vary, depending on the selected system boundary, i.e. the decision‐making perspective, the type of CHP plant and energy prices. Based on the results of this study, the exergy method fits well with the CCGT plant with a condensing unit and constant fuel input. On the other hand, the market‐based method is the most correct way to estimate the value of heat when heat conservation reduces the production of CHP electricity. Copyright © 2010 John Wiley & Sons, Ltd.