Biomass ash-based mineral admixture prepared from municipal sewage sludge and its application in cement composites

Biomass as the biodegradable fraction of both agricultural products and industrial and municipal waste is currently a versatile energy resource. It can be stored and converted in practically any form of energy carrier and also into biochemicals and biomaterials from which, once they have been used, the energy content can be recovered to generate electricity, heat, or transport fuels. Moreover, the residues of its incineration can often be reused as pozzolanic additions to cement which can be considered as an environmentally friendly way of their disposal. In this paper, municipal sewage sludge with the organic carbon content of 27% was used for the preparation of biomass ash that should potentially find use as environmentally friendly mineral admixture to construction binders. Based on physical and chemical characterization of the raw material that showed a suitable chemical and phase composition, organic matter in a significant amount, and no thermal decomposition processes above 700 °C, biomass ash was produced. The biomass ash was obtained by incineration of sewage sludge at 700 °C, and mechanical activation contained 52% of amorphous phase which correlates with its good pozzolanic activity. The concentration of heavy metals, soluble chlorides, nitrates, and sulfates in biomass ash is found well below the standard permissible values. The composites prepared with a biomass ash dosage of 10, 20, and 30 wt% of Portland cement exhibited good functional properties. The increase in porosity up to 6% and decrease in compressive strength up to 3% were satisfactory. The results of leaching tests showed that composites with biomass ash contain only trace amounts of chlorides, nitrates, and sulfates. Apparently, the chlorides contained in biomass ash (0.7 mg/g) were immobilized in the cement matrix because the amounts of leached chlorides (0.04 wt%) were the same for all composites and well below the permissible limit for concrete. As revealed by the X-ray diffraction and thermogravimetric analyses, a significant decrease in portlandite content with increasing biomass ash content confirmed the pozzolanic reaction in biomass ash containing composite mixes. The environmental assessment showed a significant decrease in both carbon dioxide production and energy consumption with the increasing biomass ash content. For the composite with 30% biomass ash dosage, it was 21% of CO₂ and 11% of energy, as compared with the reference mix. The combination of good functional and environmental parameters of the analyzed composites makes good prerequisites for their application in construction industry. Taylor-made mineral admixture on biomass ash basis can find a broad use as eco-efficient admixture to cement- and lime-based binders.     

Plasmachemical synthesis of maghemite nanoparticles in atmospheric pressure microwave torch

The powder of γ − Fe₂O₃ nanoparticles was synthesized in microwave torch at atmospheric pressure from 0.05 sccm of Fe(CO)₅ vapors in 670 sccm of argon. The optimization of the torch reactor design and deposition conditions allowed continual synthesis of γ − Fe₂O₃ nanoparticles at low power consumption. The synthesized powder was collected at the reactor walls and analyzed by TEM, X-ray diffraction and Raman spectroscopy without any further purification or treatment. The mean diameter of NPs, as observed by TEM, was 12 nm with a 90% confidence interval 5.5-22 nm.     

Seminal fluid and sperm diluent affect sperm metabolism in an insect: Evidence from NAD(P)H and flavin adenine dinucleotide autofluorescence lifetime imaging

Sperm metabolism is fundamental to sperm motility and male fertility. Its measurement is still in its infancy, and recommendations do not exist as to whether or how to standardize laboratory procedures. Here, using the sperm of an insect, the common bedbug, Cimex lectularius, we demonstrate that standardization of sperm metabolism is required with respect to the artificial sperm storage medium and a natural medium, the seminal fluid. We used fluorescence lifetime imaging microscopy (FLIM) in combination with time-correlated single-photon counting (TCSPC) to quantify sperm metabolism based on the fluorescent properties of autofluorescent coenzymes, NAD(P)H and flavin adenine dinucleotide. Autofluorescence lifetimes (decay times) differ for the free and protein-bound state of the co-enzymes, and their relative contributions to the lifetime signal serve to characterize the metabolic state of cells. We found that artificial storage medium and seminal fluid separately, and additively, affected sperm metabolism. In a medium containing sugars and amino acids (Grace's Insect medium), sperm showed increased glycolysis compared with a commonly used storage medium, phosphate-buffered saline (PBS). Adding seminal fluid to the sperm additionally increased oxidative phosphorylation, likely reflecting increased energy production of sperm during activation. Our study provides a protocol to measure sperm metabolism independently from motility, stresses that protocol standardizations for sperm measurements should be implemented and, for the first time, demonstrates that seminal fluid alters sperm metabolism. Equivalent protocol standardizations should be imposed on metabolic investigations of human sperm samples.     

Soil burdens of persistent organic pollutants — Their levels, fate and risks: Part III. Quantification of the soil burdens and related health risks in the Czech Republic

A total number of 471 soil samples collected during the period of 1996-2006 from the agricultural and forest areas of the Czech Republic were analyzed for their content of persistent organic pollutants (POPs). Spatial variability of the POP concentrations was assessed using an IDW spatial GIS model analysis. For every grid of the network, resulting modeled levels of contamination allowed for estimation of the total burden of POPs in soils. Potential risks associated with contaminated soils were assessed as well. Database of the old ecological burdens counting 3061 sampling sites was used to adjust the model and incorporate the risks of heavily contaminated sites. The high levels of health risks were only found at less than 1% of the area of interest. The IDW modeling proved to be a useful tool for screening of the health risks in the large areas with scarce monitoring data. Presented approach can be applied in the risk management, to support an efficient targeting of the risk reduction measures, or to improve a design of the national monitoring.     

Examination of catalytic roles of inherent metallic species in steam reforming of nascent volatiles from the rapid pyrolysis of a brown coal

In-situ steam reforming of tar from the rapid pyrolysis of a Victorian brown coal was studied, employing a single-stage drop-tube reactor and a particular type of two-stage reactor, in which the nascent tar underwent steam reforming and thermal cracking in the presence and absence of nascent char particles, respectively. Na was the most abundant inherent metallic species contained in the coal, and a significant proportion of Na (60–80%) was volatilized during the pyrolysis. However, the Na dispersed in the vapor phase seemed to have no significant catalytic effect on the steam reforming. Na, and/or Ca remaining on the surface of char particles were responsible for rapid and extensive steam reforming of the nascent tar into gases, resulting in tar yield decrease by nearly 90%. The presence of steam alone was effective for suppressing soot formation from the tar vapor by approx. 80%, but in the absence of char particles containing metallic species, the addition of steam led to an increase in the yield of poly-nuclear aromatics.     

Comparison of selected physical and mechanical properties of densified beech wood plasticized by ammonia and saturated steam

Gaseous ammonia treatment in combination with densification of wood has been known for several decades, but these days there is no industrial production of materials modified in this way; also, little has been published in this area of wood science. In this study, selected physical and mechanical properties, i.e. density profile, bending strength, hardness and moisture absorption were investigated for Lignamon (1), which was obtained from the Czech industrial production. Selected properties were also investigated using steam-densified beech (2) and native beech (3) and compared with each other. Densitometry of Lignamon showed a large variability in the density profile compared to that of only densified beech. It is affected by the degree of densification, temperature and moisture gradients, and their relationship to the glass transition of the wood cell wall. Modulus of elasticity, hardness, moisture exclusion and anti-swelling efficiency of Lignamon are enhanced compared to densified beech. The enhanced dimensional stability and lower hygroscopicity of Lignamon are probably caused by heat treatment during the process. Further investigation will be carried out with self-produced Lignamon samples.     

Block-wise construction of tree-like relational features with monotone reducibility and redundancy

We describe an algorithm for constructing a set of tree-like conjunctive relational features by combining smaller conjunctive blocks. Unlike traditional level-wise approaches which preserve the monotonicity of frequency, our block-wise approach preserves monotonicity of feature reducibility and redundancy, which are important in propositionalization employed in the context of classification learning. With pruning based on these properties, our block-wise approach efficiently scales to features including tens of first-order atoms, far beyond the reach of state-of-the art propositionalization or inductive logic programming systems.     

Pervaporation of dichloromethane-cyclopentane and methylal-cyclopentane mixtures through membranes from chloroprene rubber

Chloroprene rubber (CR) has been commonly applied in various branches of the industry but its application in selective layers of pervaporation membranes remains overseen. To survey its applicability, we report on the pervaporation of two close-boiling azeotrope-forming systems of common solvents, blowing agents, adjuvants, and refrigerants, namely, dichloromethane-cyclopentane (DCM-CP) and methylal-cyclopentane (ML-CP). Vulcanizates having the form of thin films (66 ± 5 μm) have been prepared from the crystallization-resistant (WRT) polychloroprene by using nanoparticles of ZnO and MgO. Mechanical and thermal properties have been characterized using dynamic mechanical analysis (DMA) and thermogravimetry analysis, spectral properties using ATR-FTIR. Plasticization has been assessed by measuring DMA characteristics for the CR films exposed to vapors of the studied compounds. The CR films are preferentially permeable to DCM and ML over CP, break the respective azeotropes, and show comparable selectivity ranging from 1.1 to 1.7 for DCM-CP and from 1.0 to 1.8 for ML-CP. Importantly, plasticization of the CR membranes by DCM and ML enhances the selectivity and, simultaneously, the transmembrane flux. Overall, we show that membranes from CR enable selective and intensive pervaporative recovery of halogenated hydrocarbons from their mixtures with hydrocarbons, which is relevant, for instance, for the recycling of blowing agents.