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41.
Jozef Rychlý Martina Hudáková Lyda Rychlá 《Journal of Thermal Analysis and Calorimetry》2014,115(1):527-535
The burning of polyethylene in the mixture with aluminium hydroxide, aluminium oxide, cellulose and Irganox 1010 has been examined by cone calorimeter under non-standard sizes of the sample. The time to ignition of pure polyethylene decreases with decreasing initial amount of polyethylene powder. The subtraction of the mass of water released from the total mass lost for polyethylene with aluminium hydroxide give the same values of effective heats of combustion as for pure polyethylene up to the load about 50 mass% of aluminium hydroxide. The mean heats of combustion determined from the cone calorimeter software are higher than those determined from the total oxygen consumed and mass lost multiplied by the factor 13.1. The additivity rule was found for effective heat of combustion and total smoke released for polyethylene with cellulose. The free radical scavenger Irganox 1010 does not show a significant effect on the flammability of polyethylene except for the increase of the total smoke released. The equation describing the heat release rate evolution in time has been proposed showing a good fit to the experimental runs. 相似文献
42.
Regina J. Patinvoh Elisabeth Feuk-Lagerstedt Magnus Lundin Ilona Sárvári Horváth Mohammad J. Taherzadeh 《Applied biochemistry and biotechnology》2016,180(7):1401-1415
Chicken feathers are available in large quantities around the world causing environmental challenges. The feathers are composed of keratin that is a recalcitrant protein and is hard to degrade. In this work, chicken feathers were aerobically pretreated for 2–8 days at total solid concentrations of 5, 10, and 20 % by Bacillus sp. C4, a bacterium that produces both α- and β-keratinases. Then, the liquid fraction (feather hydrolysate) as well as the total broth (liquid and solid fraction of pretreated feathers) was used as substrates for biogas production using anaerobic sludge or bacteria granules as inoculum. The biological pretreatment of feather waste was productive; about 75 % of feather was converted to soluble crude protein after 8 days of degradation at initial feather concentration of 5 %. Bacteria granules performed better during anaerobic digestion of untreated feathers, resulting in approximately two times more methane yield (i.e., 199 mlCH4/gVS compared to 105 mlCH4/gVS when sludge was used). Pretreatment improved methane yield by 292 and 105 % when sludge and granules were used on the hydrolysate. Bacteria granules worked effectively on the total broth, yielded 445 mlCH4/gVS methane, which is 124 % more than that obtained with the same type of inoculum from untreated feather. 相似文献
43.
Kazimieras Anusevičius Ilona Jonuškienė Birutė Sapijanskaitė Kristina Kantminienė Vytautas Mickevičius 《Research on Chemical Intermediates》2016,42(9):6975-6990
N-Substituted 7-amino-4-methyl-2H-chromen-2-ones containing one or two functionalized azole or azine moieties were synthesized. The structures of all synthesized compounds were confirmed by IR, 1H NMR, and 13C NMR spectroscopy. Some of the synthesized compounds exhibited weak antibacterial activity against Rhizobium radiobacter, Escherichia coli, and Xanthomonas campestris. 相似文献
44.
Cover Picture: Darwin's Warm Little Pond: A One‐Pot Reaction for Prebiotic Phosphorylation and the Mobilization of Phosphate from Minerals in a Urea‐Based Solvent (Angew. Chem. Int. Ed. 42/2016)
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45.
Peter Hudák František Kardoš Tomáš Madaras Michaela Vrbjarová 《Czechoslovak Mathematical Journal》2016,66(4):1119-1128
We study improper interval edge colourings, defined by the requirement that the edge colours around each vertex form an integer interval. For the corresponding chromatic invariant (being the maximum number of colours in such a colouring), we present upper and lower bounds and discuss their qualities; also, we determine its values and estimates for graphs of various families, like wheels, prisms or complete graphs. The study of this parameter was inspired by the interval colouring, introduced by Asratian, Kamalian (1987). The difference is that we relax the requirement on the original colouring to be proper. 相似文献
46.
We prove that certain means of the quadratical partial sums of the two‐dimensional Vilenkin‐Fourier series are uniformly bounded operators from the Hardy space to the space for We also prove that the sequence in the denominator cannot be improved. 相似文献
47.
An increasing number of diseases, including Alzheimer's, have been found to be a result of the formation of amyloid aggregates that are practically independent of the original primary sequence of the protein(s). (Eakin, C. M.; Berman, A. J.; Miranker, A. D. Nat. Struct. Mol. Biol. 2006, 13, 202-208.) Consequently, the driving force of the transformation from original to disordered amyloid fold is expected to lie in the protein backbone, which is common to all proteins. (Nelson, R.; Sawaya, M. R.; Balbirnie, M.; Madsen, A. O.; Riekel, C.; Grothe, R.; Eisenberg, D. Nature 2005, 435, 773-778. Wright, C. F.; Teichmann, S. A.; Clarke, J.; Dobson, C. M. Nature 2005, 438, 878-881.) However, the exact explanation for the existence of such a "dead-end" structure is still unknown. Using systematic first principle calculations on carefully selected but large enough systems modeling the protein backbone we show that the beta-pleated sheet structure, the building block of amyloid fibers, is the thermodynamically most stable supramolecular arrangement of all the possible peptide dimers and oligomers both in vacuum and in aqueous environments. Even in a crystalline state (periodical, tight peptide attechment), the beta-pleated sheet assembly remains the most stable superstructure. The present theoretical study provides a quantum-level explanation for why proteins can take the amyloid state when local structural preferences jeopardize the functional native global fold and why it is a beta-pleated sheetlike structure they prefer. 相似文献
48.
Dimers of free nucleobases with their conjugate acid ions can be assigned to either of two categories: protonated dimers or proton-bound dimers. In the former, the extra proton attaches to a lone pair of a neutral dimer. In the latter, the extra proton is situated between two lone pairs and participates in a proton bridge. In general, proton-bound dimers are found to be more tightly held together than protonated dimers. While neutral adenine and its isomer 8-aminopurine (C(5)H(5)N(5)) are substantially more stable than their 7H tautomers, their conjugate acid ions and those of their respective 7H tautomers have nearly the same heats of formation. Correspondingly, the most stable (C(5)H(5)N(5))2H+ structures contain 7H tautomers as the neutral partner. Proton transit from one partner to the other within the most stable protonated dimer of 8-aminopurine has a low barrier (6 kJ mol(-1)). The potential energy curve for the NH stretch in that case is better fitted as a double minimum rather than as a harmonic potential. Purine-purine mismatches have been observed in nucleic acids, to which calculated (C(5)H(5)N(5))2H+ dimer geometries appear nearly isosteric. 相似文献
49.
Ewald Sattler Harald Krautscheid Eberhard Matern Gerhard Fritz Ilona Kovcs 《无机化学与普通化学杂志》2001,627(2):186-193
Formation and Reactions of the CH2Li‐Derivatives of tBu2P–P=P(CH3)tBu2 and (Me3Si)tBuP–P=P(CH3)tBu2 With nBuLi, (Me3Si)tBuP–P=P(CH3)tBu2 ( 1 ) and tBu2P–P=P(CH3)tBu2 ( 2 ) yield (Me3Si)tBuP–P=P(CH2Li)tBu2 ( 3 ) and tBu2P–P=P(CH2Li)tBu2 ( 4 ), wich react with Me3SiCl to give (Me3Si)tBuP–P=P(CH2–SiMe3)tBu2 ( 5 ) and tBu2P–P=P(CH2–SiMe3)tBu2 ( 6 ), respectively. With tBu2P–P(SiMe3)–PtBuCl ( 7 ), compound 3 forms 5 as well as the cyclic products [H2C–P(tBu)2=P–P(tBu)–PtBu] ( 8 ) and [H2C–P(tBu)2=P–P(PtBu2)–P(tBu)] ( 9 ). Also 3 forms 8 with tBuPCl2. The cleavage of the Me3Si–P‐bond in 1 by means of C2Cl6 or N‐bromo‐succinimide yields (Cl)tBuP–P=P(CH3)tBu2 ( 10 ) or (Br)tBuP–P=P(CH3)tBu2 ( 11 ), resp. With LiP(SiMe3)2, 10 forms (Me3Si)2P–P(tBu)–P=P(CH3)tBu2 ( 12 ), and Et2P–P(tBu)–P=P(CH3)tBu2 ( 13 ) with LiPEt2. All compounds are characterized by 31P NMR Data and mass spectra; the ylide 5 and the THF adduct of 4 additionally by X‐ray structure analyses. 相似文献
50.
Andrew Coop Ilona Berzetei‐Gurske Jackie Burnside Lawrence Toll JohnR. Traynor StephenM. Husbands JohnW. Lewis 《Helvetica chimica acta》2000,83(4):687-693
A series of ethers of 7,8‐cyclopenta‐fused analogs of the orvinols related to buprenorphine were prepared and evaluated in opioid‐binding and functional assays. Comparison of the ethyl ethers 4b and 5b with the parent alcohols 4a and 5a , respectively, in both the (5′R) (=5′β) and (5′S) (=5′α) series, shows that the 20‐OH group in the orvinols (corresponding to 5′‐OH of 4 and 5 ) is not crucial for opioid activity, although in the [35S]GTPγS assay, the 5′β‐ethyl ether 4b had 80‐fold greater κ‐agonist potency than its epimer 5b . Increasing the size of the 5′β‐OR group has a major effect on μ‐agonist efficacy and potency, a more modest effect on δ‐efficacy, and no effect on κ‐activity. These data show that μ‐ and δ‐agonist efficacy is favoured by lipophilic binding in the area occupied by the tBu in the lowest‐energy conformation of buprenorphine, and that κ‐agonist binding may involve interaction with an H‐bond‐donor group in that region. 相似文献