Reuse of waste sludge from papermaking process in cement composites

Papermaking sludge (PS), a waste residue from the pulp and paper processing, has brought great pressure on the environment because of large quantities that are produced in paper mills. This work was carried out to explore the possibility of making PS/cement composite products using solid waste of PS. Boards measuring 350 × 270 × 12 mm³ were manufactured using PS contents of 40, 50, and 60 wt%, adhesive dosages of 0, 10, and 15 wt%, and 0 and 5 wt% of calcium chloride as an accelerator. At least three replications were fabricated for each treatment, and some mechanical and physical properties of the boards were evaluated. Test results showed that the bending and internal strengths of the specimens decreased with an increase in the PS content, and the maximum values were obtained at PS loading of 40 wt%. The negative influence of PS content on the mechanical properties can be explained by the reduced bonding ability because of weaker PS compared with cement. Screw withdrawal values were up to 22.7 kPa. Water absorption and thickness swelling of cement mortar considerably increased with increased content of PS, with a corresponding reduction of bulk density. In general, all properties of the boards were improved when the adhesive and calcium chloride contents were increased. The results showed that an increase in board density improved the mechanical and physical properties. Finally, results showed that PS has good potential for recycling and utilization in developing value‐added building components. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Polypropylene/date stone flour composites: Effects of filler contents and EBAGMA compatibilizer on morphology,thermal, and mechanical properties

This work aims to study the effects of date stone flour (DSF) on morphology, thermal, and mechanical properties of polypropylene (PP) composites in the absence and presence of ethylene‐butyl acrylate‐glycidyl methacrylate (EBAGMA) used as the compatibilizer. DSF was added to the PP matrix at loading rates of 10, 20, 30, and 40 wt %, while the amount of compatibilizer was fixed to the half of the filler content. The study showed through scanning electron microscopy analysis that EBAGMA compatibilizer improved the dispersion and the wettability of DSF in the PP matrix. Thermogravimetric analysis (TGA) indicated a slight decrease in the decomposition temperature at onset (T_onset) for all composite materials compared to PP matrix, whereas the thermal degradation rate was slower. Differential scanning calorimetry (DSC) data revealed that the melting temperature of PP in the composite materials remained almost unchanged. The nucleating effect of DSF was however reduced by the compatibilizer. Furthermore, the incorporation of DSF resulted in the increase of stiffness of the PP composites accompanied by a significant decrease in both the stress and strain at break. The addition of EBAGMA to PP/DSF composites improved significantly the ductility due to the elastomeric effect of EBAGMA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Digital image correlation analysis and modelling of the strain rate in metal cutting

In the last eight decades, considerable modelling and computational efforts have been made to predict the strain rate during cutting with the aim of optimizing machining processes. However, the validation of these modelling approaches on a local scale remains excessively limited due to the lack of in-situ measurements and the faulty existing quick-stop tests. This work presents the in-process analysis of the strain rate and strain in the primary shear zone using high speed Digital Image Correlation (DIC) techniques. The comparison of measured and computed results shows the suitability of the DIC techniques and the robustness of the modelling approaches.     

Grid automata and supervisory control of dense real-time discrete event systems

We present a generalization of the classical supervisory control theory for discrete event systems to a setting of dense real-time systems modeled by Alur and Dill timed automata. The main problem involved is that in general the state space of a timed automaton is (uncountably) infinite. The solution is to reduce the dense time transition system to an appropriate finite discrete subautomaton, the grid automaton, which contains enough information to deal with the timed supervisory control problem (TSCP). The plant and the specifications region graphs are sampled for a granularity defined in a way that each state has an outgoing transition labeled with the same time amount. We redefine the controllability concept in the context of grid automata, and we provide necessary and sufficient solvability conditions under which the optimal solution to centralized supervisory control problems in timed discrete event systems under full observation can be obtained. The enhanced setting admits subsystem composition and the concept of forcible event. A simple example illustrates how the new method can be used to solve the TSCP.     

Goats' milk xanthine oxidoreductase is grossly deficient in molybdenum

Xanthine oxidoreductase (XOR) was purified from goats' milk. The u.v.-visible absorption spectrum was essentially identical to those of the corresponding bovine and human milk enzymes and showed an A280/A450 ratio of 5.20+/-0.12, indicating a high degree of purity. Like bovine and human milk XORs, enzyme purified from goats' milk showed a single band on SDS-PAGE corresponding to a subunit with approximate Mr 150,000. On Western blotting, mouse monoclonal anti-human XOR antibody cross-reacted with purified caprine and bovine XORs. The specific xanthine oxidase activity of goats' milk XOR, however, was very much lower than that of bovine XOR, although NADH oxidase activities of XOR from the two sources were similar. In these respects, the caprine milk XOR mirrors the human milk enzyme, in which case the kinetic effects have previously been attributed to relatively low molybdenum content. The molybdenum content of goats' milk XOR also was shown to be relatively low, with 0.09 atoms Mo per subunit, compared with 055 atoms Mo per subunit for the bovine enzyme. A parallel purification of human milk XOR showed 0.03 atoms Mo per subunit. The possible physiological significance of the low molybdenum content of the caprine milk enzyme and of its correspondingly low enzymic activity is discussed.     

Frequency dispersion of electro-optical properties over a wide range by means of time-response analysis

We show that a Z-transform-based time-response analysis of the electro-optical response of a crystal to a step voltage with a short rise time allows one to obtain the dispersion of the electro-optical coefficients over a wide frequency range. We describe the method employed and present the results obtained for the main electroptic coefficients (r22, r61, and rc) of a standard LiNbO3 crystal. We also show that this method is able to provide even small values of the electro-optic coefficient as well as the dispersion within a wide frequency range, which is limited only by the rise time of the step voltage.     

Impedance studies on plasticized PMMA-LiX [X: CF3SO3, N(CF3SO2)2−] polymer electrolytes

Plasticized polymer electrolytes composed of poly(methylmethacrylate) (PMMA) as the host, propylene carbonate (PC) or ethylene carbonate (EC) as a plasticizer and LiX (X: CF₃SO₃⁻ or N(CF₃SO₂)₂⁻) as a salt were prepared by the solution cast technique. Impedance spectroscopy was performed in the temperature range between 303 and 383 K. In this paper, we report the electrical properties of polymer electrolytes with different lithium salts and plasticizers. The polymer electrolytes investigated exhibited high ionic conductivity at room temperature in the range of 10^− 6 to 10^− 4 S cm^− 1. The temperature dependence studies showed that the samples were ionic conductors and seemed to obey the Vogel-Tamman-Fulcher (VTF) rule. FTIR spectroscopy studies confirmed the polymer-salt interaction.     

Synthesis of high purity Tl1212 superconductor with ultrafine grains from coprecipitated Tl-free precursor route

In this study, high purity and fine-grained Tl1212 superconductor samples were successfully synthesized from Tl_0.8Bi_0.2Sr₂Ca_0.8Y_0.2Cu₂O₇ starting composition by a two-step solid-state reaction method using Tl-free precursor powder prepared from coprecipitation method. XRD pattern of the sample, which was sintered at 1,000 °C for 6 min essentially showed formation of high purity 1212 phase. The sample’s zero resistance critical temperature, T _{c zero} was 91 K and bulk critical current density, J _c measured at 40 K in zero magnetic field was 11.2 A/cm². SEM investigation on the sample revealed ultrafine homogeneous grains that are randomly orientated with grain sizes of approximately 0.5–1 μm. Resintering the sample did not affect its superconducting properties but induced clustering of grains as observed by SEM. It is suggested that the sample be used in specialized measurement techniques such as in ultrasonic studies where high purity and ultrafine-grained samples are required.     

Inducement of Itinerant Electron Transport in Charge-Ordered Pr<Subscript>0.6</Subscript>Ca<Subscript>0.4</Subscript>MnO<Subscript>3</Subscript> by Ba Doping

The effects of Ba ²⁺ doping on the electrical and magnetic properties of charge-ordered Pr_0.6Ca_0.4MnO₃ were investigated through electrical resistivity and AC susceptibility measurements. X-ray diffraction data analysis showed an increase in unit cell volume with increasing Ba ²⁺ content indicating the possibility of substituting Ba ²⁺ for the Ca-site. Electrical resistivity measurements showed insulating behavior and a resistivity anomaly at around 220 K. This anomaly is attributed to the existence of charge ordering transition temperature, \(T^{\mathrm {R}}_{\text {CO}}\) for the x = 0 sample. The Ba-substituted samples exhibited metallic to insulator transition (MI) behavior, with transition temperature, T _MI, increasing from ～98 K (x = 0.1) to ～122 K (x = 0.3). AC susceptibility measurements showed ferromagnetic to paramagnetic (FM-PM) transition for Ba-substituted samples with FM-PM transition temperature, T _c, increasing from ～121 K (x = 0.1) to ～170 K (x = 0.3), while for x = 0, an antiferromagnetic to paramagnetic transition behavior with transition temperature, T _N, ～170 K was observed. In addition, inverse susceptibility versus T plot showed a deviation from the Curie–Weiss behavior above T _c, indicating the existence of the Griffiths phase with deviation temperature, T _G, increasing from 160 K (x = 0.1) to 206 K (x = 0.3). Magnetoresistance, MR, behavior indicates intrinsic MR mechanism for x = 0.1 which changed to extrinsic MR for x > 0.2 as a result of Ba substitution. The weakening of charge ordering and inducement of ferromagnetic metallic (FMM) state as well as increase in both T _c and T _MI are suggested to be related to the increase of tolerance factor, τ, and increase of e _g ?electron bandwidth as average ionic radius at A-site, <r _A> increased with Ba substitution. The substitution may have reduced MnO₆ octahedral distortion and changed the Mn–O–Mn angle which, in turn, promotes itinerancy of charge carrier and enhanced double exchange mechanism. On the other hand, increase in A-site disorder, which is indicated by the increase in σ ² is suggested to be responsible for the widening of the difference between T _c and T _MI.     

Using bottom surface reflectance to map coastal marine areas: a new application method for Lyzenga's model

Remote sensing is widely used in coastal management. Lyzenga's model has been traditionally used to explain the relationship between bottom surface reflectance and the radiance level measured by satellite. Due to its central assumption, this model lacks accuracy compared with the other radiative transfer models. Nonetheless, it enables, with a single and simple equation, representation of the multiple optical processes taking place in coastal areas. Mapping processes associated with this model may include radiometric correction, a technique previously pointed out as a major driver of mapping accuracy. Radiometric correction is generally based on a depth-invariant index, efficient for clear waters (Jerlov water type I to II) but largely unsuitable when transparency decreases (Jerlov water type II to III). In order to overcome this problem, we developed a new index for radiometric correction, which combines bathymetry data with attenuation coefficients. The improved efficiency of our model with regard to the traditional depth invariant index was demonstrated through two case studies: Funakoshi Bay (Japan; Jerlov water type II) and the Gabes Gulf part located off Mahares (Tunisia; Jerlov water type II to III).