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[en] In spite of the fact that gypsum is one of the most environmentally friendly binders, utilization of gypsum products is relatively narrow. The main problem of gypsum materials is their low resistance to the wet environment and radical decrease of mechanical properties with increasing moisture. The solution of the problem could be in use of composed gypsum-based binders, usually ternary, comprising gypsum, pozzolan and alkali activator of pozzolan reaction. These materials have a better moisture resistance and often also better mechanical properties. Paper provides literature survey of the possible compositions, properties and ways of utilization of the composed gypsum-based binders with latent hydraulic and pozzolan materials together with some results of present research performed by authors. (paper)
[en] In this paper, properties of composite materials containing ternary binders are determined. Except gypsum, ternary binders containing also pozzolans and alkaline component, which serve as an activator of pozzolanic reaction. The main aim of this research was to investigate changes in physical and chemical properties and pore structural characteristics due to additions of ternary binders. Experimental results showed that changes in the properties of the composite depend not only on the amount of the addition, but also on the kind of pozzolan. (paper)
[en] Highlights: • Night ventilation were tested in combination with PCM-impregnated gypsum boards. • The Price-based method were experimentally used to perform peak load shifting. • Importance of the application of a smart control were experimentally investigated. • A cost and energy saving up to 93% and 92% per day respectively were achieved. - Abstract: In recent years, as a result of the continuous increase in energy demand, the use of energy storage has become increasingly important. To address this problem, the application of phase change materials (PCM) in buildings has received attention because of their high energy storage density and their ease of incorporation in building envelopes. Despite large experimental works conducted on the application phase change materials in buildings, there is very little work done on this application in combination with night ventilation. In this study, the application of night ventilation in combination with PCM-impregnated gypsum boards for cooling purposes was experimentally investigated. Two identical test huts equipped with “smart” control systems were used for testing the concept. One hut was constructed using impregnated gypsum boards, while the other hut was finished with ordinary gypsum board. Initially an air conditioning (AC) unit, without night ventilation, was used in both huts to charge the PCM during low peak period, showing very little savings in electricity. However, when night ventilation was used to charge the PCM instead, a weekly electricity saving of 73% was achieved.
[en] Magnetic resonance (MR) techniques are increasingly used to improve our understanding of the multi-component, multi-phase processes encountered in chemical engineering. This review brings together many of the MR techniques used, and often developed specifically, to study chemical engineering systems and, in particular, processes occurring within porous media. Pulse sequences for relaxometry, pulsed field gradient measurements of diffusion, imaging and velocimetry measurements are described. Recent applications of these MR pulse sequences to microporous, mesoporous and macroporous structures are then reviewed. Considering the microporous and mesoporous systems, we focus attention on studies of rock cores, manufactured materials such as cement and gypsum plaster, and catalysts. When considering macroporous structures, the transport through packed beds of particles typical of fixed-bed catalytic reactors is reviewed; a brief overview of the increasing research interest in gas-solid fluidized beds is also presented. We highlight the field of sparse k-space sampling as an area that is in its infancy and suggest that, combined with Bayesian methods, it will offer new opportunities in both extending the application of high-field MR techniques to chemical engineering and increasing the range of measurements that can be carried out using low-field hardware.
[en] The behaviour of thermoluminescence glow peaks of natural barite after exposure to doses less than 2000 rads show some differences, both in the shape of the glow curve as well as in the order of kinetics relative to doses of more than 2000 rads. Details are given of the glow-curve kinetics which are of a type not previously reported for natural barite. Determination of the fundamental parameters, activation energies and frequency factors enables theoretical estimates of the glow curve shape to be made using computer calculations. The agreement between theory and experiment is quite satisfactory. (author)
[en] Thermal stability of the ESR signals from barites in chimneys deposited from hydrothermal vents is investigated using isothermal and isochronal annealing experiments. A combination of first and second order kinetics is required to explain the results. The Arrhenius plots of the decay rate constants give the activation energies of 1.0-1.3 eV. From the estimated decay rate constants at the sea bottom (3 oC), the decay rate of the signal was calculated to be less than 2% for the period of 20 ka, suggesting the applicability of the ESR method for dating barites up to about twenty thousand years.
[en] Highlights: • We study the ability of anhydrite surfaces to uptake dissolved Pb. • Experiments were conducted using Pb concentrations between 10 and 1000 mg/L. • Concentration of dissolved Pb decreased to reach a final value of ∼3.0 mg/L. • Epitactic growth of anglesite (PbSO4) on anhydrite occurs when [Pbaq]0 ⩾ 50 mg/L. • Anhydrite deserves to be taken into account when developing Pb-removal strategies. - Abstract: The fate of harmful metals in the Earth crust is importantly affected by sorption processes on mineral surfaces. Here, a study of the ability of anhydrite surfaces to uptake dissolved Pb is presented. Experiments were conducted at room temperature using initial Pb concentration ([Pbaq]0) ranging between 10 and 1000 mg/L and a batch type set-up. Inductively coupled plasma optical emission spectrometry analyses showed that [Pbaq] progressively decreased as the time of interaction increased, to reach a final steady state value of ∼3.0 mg/L, irrespectively of [Pbaq]0. However, the time elapsed before the steady state value was reached strongly depended on [Pbaq]0, with the drop to this final value occurring in less than 1 day interaction when [Pbaq]0 ⩾ 50 mg/L and after 20 days when [Pbaq]0 < 50 mg/L. Scanning Electron Microscopy and X-ray diffraction analyses confirmed the epitactic growth of anglesite (PbSO4) crystals on anhydrite surfaces when [Pbaq]0 ⩾ 50 mg/L. X-ray Absorption Near Edge Structure spectroscopy points to a different sorption mechanisms when [Pbaq]0 < 50 mg/L. The results show that the epitactic growth of anglesite on anhydrite has no significant impact on the ability of anhydrite surfaces to remove Pbaq, which show equal effectiveness as that of gypsum surfaces. The high reactivity of anhydrite surfaces renders this phase potentially important in the control of the fate of dissolved metals in nature
[en] A 2S albumin from L. culinaris was purified and crystallized and preliminary crystallographic studies were carried out. Lens culinaris (lentil) is a widely consumed high-protein-content leguminous crop. A 2S albumin protein (26.5 kDa) has been identified using NH2-terminal sequencing from a 90% ammonium sulfate saturation fraction of total L. culinaris seed protein extract. The NH2-terminal sequence shows very high homology to PA2, an allergy-related protein from Pisum sativum. The 2S albumin protein was purified using a combination of size-exclusion and ion-exchange chromatography. Crystals of the 2S seed albumin obtained using the hanging-drop vapour-diffusion method diffracted to 2.5 Å resolution and were indexed in space group P41 (or P43), with unit-cell parameters a = b = 78.6, c = 135.2 Å