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731.
Characteristics of the medium-range order (MRO) of K2O-GeO2-P2O5 (KGP) glasses are obtained from X-ray and neutron scattering data. The behavior of the MRO is expressed in changes of pre-peaks and smooth contributions in the structure factors, S(Q), for Q < 12 nm-1. Peaks at Q = (7.5 ± 0.5) nm-1 (Q - magnitude of the scattering vector) are the outstanding features and reach maximum intensity for a glass of ∼25/50/25 mol% K2O/GeO2/P2O5. The pre-peaks are explained by a structural model in which K-rich and Ge-rich regions are separated by PO4 units. The distance of repetition of similar regions (∼1 nm) is responsible for the pre-peak at ∼7.5 nm-1. The intensity of this pre-peak is reduced and finally eliminated for glass compositions approaching the binary GeO2-P2O5 system. The pre-peak is changed to a smooth scattering contribution and finally shifted to ∼9 nm-1 for glass compositions approaching the binary K2O-GeO2 system. The strong tendency of the PO4 units to coordinate K+ and Ge neighbors at their four corners is the source for the special MRO of the KGP glasses. 相似文献
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Mziyanda Mbaba Laura M. K. Dingle Ayanda I. Zulu Dustin Laming Tarryn Swart Jo-Anne de la Mare Heinrich C. Hoppe Adrienne L. Edkins Setshaba D. Khanye 《Molecules (Basel, Switzerland)》2021,26(5)
A tailored series of coumarin-based ferrocenyl 1,3-oxazine hybrid compounds was synthesized and investigated for potential antiparasitic activity, drawing inspiration from the established biological efficacy of the constituent chemical motifs. The structural identity of the synthesized compounds was confirmed by common spectroscopic techniques: NMR, HRMS and IR. Biological evaluation studies reveal that the compounds exhibit higher in vitro antiparasitic potency against the chemosensitive malarial strain (3D7 P. falciparum) over the investigated trypanosomiasis causal agent (T. b. brucei 427) with mostly single digit micromolar IC50 values. When read in tandem with the biological performance of previously reported structurally similar non-coumarin, phenyl derivatives (i.e., ferrocenyl 1,3-benzoxazines and α-aminocresols), structure-activity relationship analyses suggest that the presence of the coumarin nucleus is tolerated for biological activity though this may lead to reduced efficacy. Preliminary mechanistic studies with the most promising compound (11b) support hemozoin inhibition and DNA interaction as likely mechanistic modalities by which this class of compounds may act to produce plasmocidal and antitrypanosomal effects. 相似文献
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735.
E. Hoppe 《Fresenius' Journal of Analytical Chemistry》1912,51(5):321-322
Ohne Zusammenfassung 相似文献
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Despite significant advances since the late 80's the balance between mar- and acid etch resistance of automotive clearcoats still is a subject of intense research. Among others silane- and PUR technology is used to produce clearcoats today. Generally speaking the silane based systems show better mar resistance whereas PUR based systems have advantages in acid etch resistance. We wish to show that a certain group of silane modified polyisocyanates can be used as crosslinkers for hybride systems exhibiting an improved balance between mar- and acid etch resistance. 相似文献
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The transition from microscale damage phenomena to crack initiation and growth at the macroscale is an important mechanism which constrains the lifetime of concrete structures. Analysing crack growth using the finite element method without enhancement of the shape functions is possible only by continuously updating the corresponding meshes, which constitutes a significant computational effort. But even then the results can be substantially mesh–dependent and hard to interpret. The extended Finite Element Method (XFEM) uses additional discontinuous shape–functions and is one possibility to overcome these problems. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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