Low strain rate plasticity of continuously cast carbon steels

By a special plastometric method, the straightening operation of a vertically cast strand of two carbon steels was simulated. The temperature dependence of the low strain rate plasticity of both the steels examined is analogous although caused by very different reasons. As to the plain carbon steel, the amount of ferrite and its location is of prime importance, whereas in the case of eutectoid steel various modes of fracture and the influence of temperature on the relative plasticity of type II MnS inclusions are influencial. To avoid transverse cracking, it seems to be suitable to keep the strand at a rather high temperature (above 900 °C). Temperature cycling seems to be fundamental as to the structural changes taking place in the strand (grain size refining, ferrite fraction if any), whereas analogous influences of straining are more or less inexpressive. Of course, the results obtained are of quality only since the practical and laboratory conditions differ significantly. The knowledge obtained could be applied in regulating the intensity of strand cooling with the aim of lowering the waste portion and improving the surface quality of worked products.     

Selective catalytic transformations of methanol to C2-C3 hydrocarbons over the new zeolite type LZ 132

The small pore zeolite HLZ 132 exhibits, in comparison with other zeolites, an increased selectivity for the transformation of methanol to ethylene in the reaction temperature range 350–500 °C: the weight ratio of C₂H₄ to C₃H₆ in the products ranges between 1 and 4 at WHSV=2 h^–1. Besides the effect of the reactant shape selectivity this fact may be interpreted by the participation of the asymmetrical methoxy groups in the surface as well as by proton-donor centres of lower acidity which do not catalyze the oligomerization of ethylene but which do the more basic molecule of propylene, thereby generating polyene-type coke.     

Polymerization of lactams, 38. Copolymerization of 6-caprolactam with some of its non-homopolymerizing derivatives

It was demonstrated that non-homopolymerizing derivatives of 6-caprolactam: 7-cyclohexyl-1-aza-2-cycloheptanone (I) and 7-isopropyl-5-methyl-1-aza-2-cycloheptanone (II) were polymerizing with 6-caprolactam under conditions of the socalled hydrolytic polymerization. With its increasing content in the initial reaction mixture the copolymerization rate, the equilibrium content of the copolymer, and the reduced viscosity decreased. Lactam (I) was a more reactive comonomer in comparison with lactam (II).     

An optimized FAIRE procedure for low cell numbers in yeast

We report an optimized low‐input FAIRE‐seq (Formaldehyde‐Assisted Isolation of Regulatory Elements‐sequencing) procedure to assay chromatin accessibility from limited amounts of yeast cells. We demonstrate that the method performs well on as little as 4 mg of cells scraped directly from a few colonies. Sensitivity, specificity and reproducibility of the scaled‐down method are comparable with those of regular, higher input amounts, and allow the use of 100‐fold fewer cells than existing procedures. The method enables epigenetic analysis of chromatin structure without the need for cell multiplication of exponentially growing cells in liquid culture, thus opening the possibility of studying colony cell subpopulations, or those that can be isolated directly from environmental samples.     

The Escherichia coli RecA protein complements recombination defective phenotype of the Saccharomyces cerevisiae rad52 mutant cells

The Saccharomyces cerevisiae rad52 mutants are sensitive to many DNA damaging agents, mainly to those that induce DNA double-strand breaks (DSBs). In the yeast, DSBs are repaired primarily by homologous recombination (HR). Since almost all HR events are significantly reduced in the rad52 mutant cells, the Rad52 protein is believed to be a key component of HR in S. cerevisiae. Similarly to the S. cerevisiae Rad52 protein, RecA is the main HR protein in Escherichia coli. To address the question of whether the E. coli RecA protein can rescue HR defective phenotype of the rad52 mutants of S. cerevisiae, the recA gene was introduced into the wild-type and rad52 mutant cells. Cell survival and DSBs induction and repair were studied in the RecA-expressing wild-type and rad52 mutant cells after exposure to ionizing radiation (IR) and methyl methanesulphonate (MMS). Here, we show that expression of the E. coli RecA protein partially complemented sensitivity and fully complemented DSB repair defect of the rad52 mutant cells after exposure to IR and MMS. We suggest that in the absence of Rad52, when all endogenous HR mechanisms are knocked out in S. cerevisiae, the heterologous E. coli RecA protein itself presumably takes over the broken DNA.     

Integrated waste-to-energy conversion and waste transportation within island communities

Usually in islands both primary energy sources and drinking water are missing. Additionally, municipal solid waste (MSW) must be managed avoiding exclusive use of landfills, which limits sustainable development. Power generation from MSW incineration contributes significantly to replacing energy produced from fossil fuels and to reduce overall emissions. A solution based on thermodynamics, environmental and economic analyses and 3D-GIS modelling for the afore-mentioned problems for Cape Verde is proposed. This model integrates waste transportation optimisation and incineration with energy recovery combining production of heat and power (CHP), the heat being used for drinking water production. The results show that extraction condensing steam turbines are more suitable when power production is a priority (5.0 MW with 4000 m³/d of drinking water), whereas back-pressure turbines yield 5540–6650 m³/d of drinking water with an additional power production of 3.3–4.7 MW. The environmental and economic assessment performed shows the feasibility of the proposed CHP solution, which brings a considerable reduction in net air emissions (1.6 kt), including a significant decrease in the greenhouse gas emissions (131 ktCO₂), and that the revenue from energy sales (€15 million) has potential to balance the incineration cost. Moreover, when terrain relief is accounted for in the route optimisation for minimum fuel consumption, savings up to 11% are obtained.     

Detection of Glycomic Alterations Induced by Overexpression of P-Glycoprotein on the Surfaces of L1210 Cells Using Sialic Acid Binding Lectins

P-glycoprotein (P-gp) overexpression is the most frequently observed cause of multidrug resistance in neoplastic cells. In our experiments, P-gp was expressed in L1210 mice leukemia cells (S cells) by selection with vincristine (R cells) or transfection with the gene encoding human P-gp (T cells). Remodeling of cell surface sugars is associated with P-gp expression in L1210 cells as a secondary cellular response. In this study, we monitored the alteration of cell surface saccharides by Sambucus nigra agglutinin (SNA), wheat germ agglutinin (WGA) and Maackia amurensis agglutinin (MAA). Sialic acid is predominantly linked to the surface of S, R and T cells via α-2,6 branched sugars that tightly bind SNA. The presence of sialic acid linked to the cell surface via α-2,3 branched sugars was negligible, and the binding of MAA (recognizing this branch) was much less pronounced than SNA. WGA induced greater cell death than SNA, which was bound to the cell surface and agglutinated all three L1210 cell-variants more effectively than WGA. Thus, the ability of lectins to induce cell death did not correlate with their binding efficiency and agglutination potency. Compared to S cells, P-gp positive R and T cells contain a higher amount of N-acetyl-glucosamine on their cell surface, which is associated with improved WGA binding. Both P-gp positive variants of L1210 cells are strongly resistant to vincristine as P-gp prototypical drug. This resistance could not be altered by liberalization of terminal sialyl residues from the cell surface by sialidase.     

Decomposition of Nitrous Oxide over Fe-Ferrierites. Effect of High-Temperature Pretreatment on the Formation of Deposited Oxygen

The dehydration of Fe-ferrierites doubled the decomposition of N₂O at 200 ° C and corresponding deposition of oxygen. The rehydration resulted in a reversible process. Samples with iron located predominantly in cationic positions (Fe/Al 0.05–0.25) exhibited the O _dep /Fe ratio of ca. 0.5 and 1 after pretreatment at 450 and 700 °C, respectively.     

Potentiation of anticancer drugs: effects of pentoxifylline on neoplastic cells

The drug efflux activity of P-glycoprotein (P-gp, a product of the mdr1 gene, ABCB1 member of ABC transporter family) represents a mechanism by which tumor cells escape death induced by chemotherapeutics. In this study, we investigated the mechanisms involved in the effects of pentoxifylline (PTX) on P-gp-mediated multidrug resistance (MDR) in mouse leukemia L1210/VCR cells. Parental sensitive mouse leukemia cells L1210, and multidrug-resistant cells, L1210/VCR, which are characterized by the overexpression of P-gp, were used as experimental models. The cells were exposed to 100 μmol/L PTX in the presence or absence of 1.2 μmol/L vincristine (VCR). Western blot analysis indicated a downregulation of P-gp protein expression when multidrug-resistant L1210/VCR cells were exposed to PTX. The effects of PTX on the sensitization of L1210/VCR cells to VCR correlate with the stimulation of apoptosis detected by Annexin V/propidium iodide apoptosis necrosis kit and proteolytic activation of both caspase-3 and caspase-9 monitored by Western blot analysis. Higher release of matrix metalloproteinases (MMPs), especially MMP-2, which could be attenuated by PTX, was found in L1210/VCR than in L1210 cells by gelatin zymography in electrophoretic gel. Exposure of resistant cells to PTX increased the content of phosphorylated Akt kinase. In contrast, the presence of VCR eliminated the effects of PTX on Akt kinase phosphorylation. Taken together, we conclude that PTX induces the sensitization of multidrug-resistant cells to VCR via downregulation of P-gp, stimulation of apoptosis and reduction of MMPs released from drug-resistant L1210/VCR cells. These facts bring new insights into the mechanisms of PTX action on cancer cells.     

Studies on the Effect of Reactive Polypropylene on the Properties of Filled Polyolefin Composites. Part 3. Effect of Maleic Anhydride Grafted Polypropylene on the Nature of Polyolefin Matrix

The effect of incorporation of maleic anhydride grafted polypropylene on the properties of composites based on separately filled polypropylene and ethylene–propylene copolymer was studied. The tensile strength and impact resistance of talc-filled polypropylene composite can be improved by optimizing the additive concentrations. On the other hand, the impact resistance of talc-filled ethylene–propylene copolymer composite hardly shows any positive effect due to the addition of maleic anhydride grafted polypropylene. The determination of melt flow index for both composite systems studied, however, indicates that addition of maleic anhydride grafted polypropylene lowers the melt viscosity of highly loaded composites.