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101.
Alfred Schmidpeter Angela Willhalm Jürgen Kroner Roberta O. Day Joan M. Holmes Robert R. Holmes 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):495-498
Abstract Phosphamethincyanines prepared in 1964 by Dimroth and Hoffmann were among the first compounds with two-coordinate phosphorus. They are special cases of 2-phospha-allylic cations. Simple representatives of this type become available from the reaction of imidoyl chlorides with tris(trimethylsily1)phosphane. 相似文献
102.
Let (X,B) be a complex projective klt pair, and let f:X→Z be a surjective morphism onto a normal projective variety with maximal albanese dimension such that KX+B is relatively big over Z. We show that such pairs have good log minimal models. 相似文献
103.
Frederic Poineau Erik V. Johnstone Alfred P. Sattelberger Kenneth R. Czerwinski 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):235-239
Technetium tetrachloride and β-TcCl3, synthesized from the reaction of Tc metal and Cl2(g) in sealed tubes, were characterized by X-ray absorption fine structure spectroscopy. Extended X-ray absorption fine structure (EXAFS) spectroscopy measurements are in good agreement with the X-ray diffraction structures of the two compounds. For TcCl4, the absorbing Tc atom is surrounded by Cl atoms at 2.34(2) Å and Tc atoms at 3.66(4) Å. For β-TcCl3, the absorbing Tc atom is surrounded by Cl atoms at 2.40(2) Å and Tc atoms at 2.81(3), 3.66(4) and 5.71(6) Å. EXAFS spectroscopy indicates that the TcCl4 and β-TcCl3 samples obtained by sealed tube reactions are single phase. The X-ray absorption near edge structure spectra of TcCl4 and β-TcCl3 were recorded; the positions of the Tc K-edges of β-TcCl3 (21,050.5 eV) and TcCl4 (21,053.0 eV) are compared to the ones measured for α-TcCl3 (21,051.0 eV) and TcCl2 (21,048.8 eV). A correlation between the positions of the Tc K-edges and the oxidation state of the Tc atom in technetium binary chlorides was determined. 相似文献
104.
Alfred D. French Monica Concha Michael K. Dowd Edwin D. Stevens 《Cellulose (London, England)》2014,21(2):1051-1063
Introductory material first describes electron density approaches and demonstrates visualization of electron lone pairs and bonding as concentrations of electron density. Then it focuses on the application of Bader’s Quantum Theory of Atoms-in-Molecules (AIM) to cellulose models. The purpose of the work is to identify the various interactions that stabilize cellulose structure. AIM analysis aids study of non-covalent interactions, especially those for which geometric criteria are not well established. The models were in the form of pairs of cellotriose molecules, methylated at the O1 and O4 ends. Based on the unit cell of cellulose Iβ, there were corner–corner, and center–center pairs that correspond to (200) sheets, and corner–center pairings that corresponded to (1–10) and (110) stacks. AIM analysis (or charge-density topology analysis) was applied before and after minimization in vacuum and in continuum solvation. Besides the conventional O–H···O hydrogen bonds, all of which were known from geometric criteria, C–H···O hydrogen bonds (some previously reported), and some O···O and H···H interactions were found. Non-covalent bonds in the (200) sheets were maintained in all calculations with the exception of a weak, bifurcated O6–H···O2′′ bond that was not found in the corner–corner pair model and did not survive minimization. Nor did the O6···O4 interactions on the reducing ends of the triosides. Pairs of molecules along the (110) plane had an equal number (12) of non-covalent bonds compared to the pairs along the (1–10) plane, but the AIM parameters indicated the bonds between the pairs in the (110) plane were weaker. Intra-molecular O–H···O hydrogen bonds survived in these minimized pairs, but the relative chain alignments usually did not. 相似文献
105.
Isobaric tagging reagents such as isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tag (TMT) typically have isotopic impurities that cause significant cross‐talk between channels. Here, we present an efficient solution to compensate for channel cross‐talk using linear algebra and find that it is between 20× and 120× faster than previous methods. We also find that the effects of channel cross‐talk are as important to manage as the effects of ratio compression because of precursor impurities, and we have released an open‐source tool to perform both types of calculations. 相似文献
106.
Hang Kuen Lau Shruti Rattan Hongbo Fu Cristobal G. Garcia Dylan M. Barber Kristi L. Kiick Alfred J. Crosby 《Macromolecular bioscience》2020,20(5)
Local, micromechanical environment is known to influence cellular function in heterogeneous hydrogels, and knowledge gained in micromechanics will facilitate the improved design of biomaterials for tissue regeneration. In this study, a system comprising microstructured resilin‐like polypeptide (RLP)–poly(ethylene glycol) (PEG) hydrogels is utilized. The micromechanical properties of RLP‐PEG hydrogels are evaluated with oscillatory shear rheometry, compression dynamic mechanic analysis, small‐strain microindentation, and large‐strain indentation and puncture over a range of different deformation length scales. The measured elastic moduli are consistent with volume averaging models, indicating that volume fraction, not domain size, plays a dominant role in determining the low strain mechanical response. Large‐strain indentation under a confocal microscope enables the visualization of the microstructured hydrogel micromechanical deformation, emphasizing the translation, rotation, and deformation of RLP‐rich domains. The fracture initiation energy results demonstrate that failure of the composite hydrogels is controlled by the RLP‐rich phase, and their independence with domain size suggested that failure initiation is controlled by multiple domains within the strained volume. This approach and findings provide new quantitative insight into the micromechanical response of soft hydrogel composites and highlight the opportunities in employing these methods to understand the physical origins of mechanical properties of soft synthetic and biological materials. 相似文献
107.
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109.
Alfred Maelicke 《Nachrichten aus der Chemie》1987,35(9):936-938
110.