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81.
As part of increasing research in the field of separation science, there have been many efforts to undertake planar chromatography with more efficient separation and better resolution in the shortest period of time, together with a specificity and a capability to identify more precisely an unknown compound present in a mixture. Ultra-thin layer chromatography (UTLC) is a modern technique which gives separation within 10–30 mm and development in just 1–6 min, with the consumption of less solvent. The stationary phase of UTLC is made up of a silica gel monolithic layer of 10 μm thickness having 3- to 4-nm mesopores and 1- to 2-μm macropores. Glancing angle deposition (GLAD)-UTLC is a modification of UTLC which gives separation within 15 mm distance and in less than 2 min. Anisotropic media of GLAD UTLC gives a unique migration direction effect. UTLC atmospheric pressure–matrix-assisted laser desorption ionizer–mass spectrometery (UTLC-AP-MALDI-MS) is a choice of technique for the identification of an unknown compound in a mixture or an impure form. ULTC-AP-MALDI-MS allows the fast changing of plates, produces more intact protonated molecules, less fragmentation and less entry of chromatographic material, and yielding less complicated spectra than the vacuum condition. Thus, UTLC is a useful technique for very rapidly giving the separation and identification of new components present in mixtures. This review provides a brief overview of UTLC, the stationary phases used for UTLC, and the detection options and applications of UTLC. 相似文献
82.
In this sequel to our previous study of the entropic and energetic costs of information erasure [N.G. Anderson, Phys. Lett. A 372 (2008) 5552], we consider direct overwriting of classical information encoded in a quantum-mechanical memory system interacting with a heat bath. Lower bounds on physical costs of overwriting – in both “single-shot” and “sequential” overwriting scenarios – are obtained from globally unitary quantum dynamics and entropic inequalities alone, all within a referential approach that grounds information content in correlations between physical system states. A heterogeneous environment model, required for consistent treatment of sequential overwriting, is introduced and used to establish and relate bounds for various cases. 相似文献
83.
One of the key steps in the synthesis of ABT-431 is the diastereoselective cyclization of thieny alcohol 1 to trans amide 2. We report a detailed study of the influence of acids, solvents and temperature over the ratio of cis and trans diastereomers. 相似文献
84.
The synthesis of a benzooxazol-5-yl acetic acid derivative (9) with strong heparanase and angiogenesis inhibitory activity, and thus possible commercial interest, is described in detail. 相似文献
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86.
Synthesis and in vitro antimicrobial screening of new pyrano[4,3-b]pyrane derivatives of 1H-pyrazole
A new series of pyrano[4,3-b]pyrane 4a-l bearing 1H-pyrazole has been synthesized by one pot base catalyzed cyclocondensation reaction of 1H-pyrazole-4-carbaldehyde la-1,malononitrile 2 and 4-hydroxy-6-methylpyrone 3.All the synthesized compounds were screened against six bacterial pathogens,namely B.subtilis,C.tetani,S.pneumoniae,S.typhi,V.cholerae, E.coli and antifungal activity against,two fungal pathogens,A.fumigatus and C.albicans using broth microdilution MIC method. Some of the compounds are found to be equipotent or more potent than that of commercial drugs,against most of employed strains. 相似文献
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88.
A. L. Roes L. B. Tabak L. Shen E. Nieuwlaar M. K. Patel 《Journal of nanoparticle research》2010,12(6):2011-2028
The goal of our study was to investigate the potential benefits of reinforcing polymer matrices with nanoobjects for structural applications by looking at both the mechanical properties and environmental impacts. For determining the mechanical properties, we applied the material indices defined by Ashby for stiffness and strength. For the calculation of environmental impacts, we applied the life cycle assessment methodology, focusing on non-renewable energy use (NREU). NREU has shown to be a good indicator also for other environmental impacts. We then divided the NREU by the appropriate Ashby index to obtain the ‘functionality-based NREU’. We studied 23 different nanocomposites, based on thermoplastic and thermosetting polymer matrices and organophilic montmorillonite, silica, carbon nanotubes (single-walled and multiwalled) and calcium carbonate as filler. For 17 of these, we saw a decrease of the functionality-based NREU with increasing filler content. We draw the conclusion that the use of nanoobjects as filler can have benefits from both an environmental point of view and with respect to mechanical properties. 相似文献
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90.
C. P. Bhasin J. P. Patel M. L. Desai 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2509-2524
Dialkyldithiophosphate derivatives of macrocyclic complexes of Pb(II), having N2S2 potential donors, of the general formula, [Pb(L)S2P(OR)2] (where L = macrocyclic ligands L1, L2, L3, L4 & L5 and R = CH3-, C3H7 n- & C3H7 i-) have been Synthesized from the reactions of [Pb(L)X2] (where X = Cl, NO3, or CH3COO) with sodium dialkyl dithiophosphates in 1:2 molar ratios in THF. Fifteen new derivatives have been synthesized by the combination of five macrocyclic complexes of 14–20 member rings with three different types of dialkyldithiophosphate. These compounds have been characterized by elemental analysis, molar conductance, molecular weight determination, IR, 1H NMR, 13C, and 31P NMR. Molecular weight determinations of these complexes indicate their monomeric nature. An octahedral structure is proposed. 相似文献