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121.
Dr. Marcin Górecki Dr. Filippo Lipparini Dr. Gianluigi Albano Dr. Tamás Jávorfi Dr. Rohanah Hussain Dr. Giuliano Siligardi Prof. Gennaro Pescitelli Prof. Lorenzo Di Bari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(4):e202103632
Solid-state ECD (ss-ECD) spectra of a model microcrystalline solid, finasteride, dispersed into a KCl pellet were recorded by using the synchrotron radiation source at the Diamond B23 beamline. Scanning a surface of 36 mm2 with a step of 0.5 mm, we measured a set of ECD imaging (ECDi) spectra very different from each other and from the ss-ECD recorded with a bench-top instrument (1 cm2 area). This is due to the anisotropic part of the ECD (ACD), which averages to zero in solution or on a large number of randomly oriented crystallites, but can otherwise be extremely large. Two-way singular value decomposition (SVD) analysis, through experimental and simulated TDDFT spectra, disclosed that the measured and theoretical principal components are in line with each other. This finding demonstrates that the observed isotropic ss-ECD spectrum is governed by the anisotropy of locally oriented crystals. It also introduces a new quality for ss-ECD measurements and opens a new future for probing and mapping chiral materials in the solid state such as active pharmaceutical ingredients (APIs). 相似文献
122.
We give a characterization of set-valued mappings from a topological (measure) space into the class of real non-empty intervals admitting a continuous (measurable) selection. As an application we obtain a characterization of set-valued functions defined on IR n admitting an approximately continuous or an approximately continuous and almost everywhere continuous selection. 相似文献
123.
Michael B. Hursthouse K. M. Abdul Malik Pradip K. Bakshi A. Afsar Bhuiyan M. Qamrul Ehsan Syed Z. Haider 《Journal of chemical crystallography》1996,26(11):739-745
Thiamine hydrochloride (vitamin B1) reacts with antimony trichloride in methanol to produce a crystalline compound which has been characterized as the salt 2[C12H18N4OS]·[Sb2Cl10] by X-ray crystallography. The compound crystallizes in the triclinic space group
,b=11.029(2),c=12.234(2) Å, =108.75(2), =102.67(2), =103.59(2)°,U=1041.52 Å3,D
c=1.80 g cm–3,Z=1. The crystal structure consists of discrete [C12H18N4OS]2+ cations and chloro bridged [Cl4Sb(-Cl)2SbCl4]4- anions in 2:1 ratio, held together by hydrogen bonds and electrostatic forces. 相似文献
124.
Prof. Dr. Jae Won Chang Dr. Mohammed Bhuiyan Dr. Hsiu-Ming Tsai Dr. Hannah J. Zhang Dr. Gang Li Dr. Shaghayegh Fathi Dr. David C. McCutcheon Dr. Lara Leoni Dr. Richard Freifelder Prof. Dr. Chin-Tu Chen Prof. Dr. Raymond E. Moellering 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15273-15277
Herein, we report the development of an 18F-labeled, activity-based small-molecule probe targeting the cancer-associated serine hydrolase NCEH1. We undertook a focused medicinal chemistry campaign to simultaneously preserve potent and specific NCEH1 labeling in live cells and animals, while permitting facile 18F radionuclide incorporation required for PET imaging. The resulting molecule, [18F]JW199, labels active NCEH1 in live cells at nanomolar concentrations and greater than 1000-fold selectivity relative to other serine hydrolases. [18F]JW199 displays rapid, NCEH1-dependent accumulation in mouse tissues. Finally, we demonstrate that [18F]JW199 labels aggressive cancer tumor cells in vivo, which uncovered localized NCEH1 activity at the leading edge of triple-negative breast cancer tumors, suggesting roles for NCEH1 in tumor aggressiveness and metastasis. 相似文献
125.
Starting from the random phase approximation for the weakly coupled multiband tightly-bounded electron systems, we calculate the dielectric matrix in terms of intraband and interband transitions. The advantages of this representation with respect to the usual planewave decomposition are pointed out. The analysis becomes particularly transparent in the long wavelength limit, after performing the multipole expansion of bare Coulomb matrix elements. For illustration, the collective modes and the macroscopic dielectric function for a general cubic lattice are derived. It is shown that the dielectric instability in conducting narrow band systems proceeds by a common softening of one transverse and one longitudinal mode. Furthermore, the self-polarization corrections which appear in the macroscopic dielectric function for finite band systems, are identified as a combined effect of intra-atomic exchange interactions between electrons sitting in different orbitals and a finite inter-atomic tunneling. 相似文献
126.
Mojca Čakić Semenčić Maja Dropučić Lidija Barišić Krešimir Molčanov Vladimir Rapić 《Structural chemistry》2007,18(3):273-278
N-Acetyl-(1-ferrocenylethyl)amine (8) was synthesized by N-acylation of (1-ferrocenylethyl)amine (7) in 84% yield. Reaction of N-acetyl-[1-(1′-bromo-ferrocenyl)ethyl]amine (4) (which was prepared by multistep sequence starting from bromoferrocene) with n-BuLi/ClCOOEt gave 77% of N-acetyl-N-ethoxycarbonyl-(1-ferrocenylethyl)amine (6) instead of the expected ethyl 1′-[1-(acetamido)ethyl]ferrocene-1-carboxylate (5). Both structures were undoubtedly confirmed by (HR)MS spectroscopy and single crystal X-ray structure analysis. 相似文献
127.
Agafonova N. Yu. Aglietta M. Antonioli P. Ashikhmin V. V. Bari G. Bruno G. Dobrynina E. A. Enikeev R. I. Fulgione W. Galeotti P. Garbini M. Ghia P. L. Giusti P. Kemp E. Malgin A. S. Molinario A. Persiani R. Pless I. A. Ryazhskaya O. G. Sartorelli G. Shakiryanova I. R. Selvi M. Trinchero G. C. Vigorito C. F. Yakushev V. F. Zichichi A. 《Journal of Experimental and Theoretical Physics》2022,134(4):449-458
Journal of Experimental and Theoretical Physics - Experimental data obtained using three scintillation detectors are analyzed. The characteristics of cosmogenic neutrons in underground experiments... 相似文献
128.
129.
A simple, facile, and high yielding stereoselective approach for the integration of α-methylene-pyrazole-carboxylates at the β-lactam nucleus is described. These monocyclic β-lactams have been synthesized by treatment of 2-phenoxy/benzylthio/phenylthio ethanoic acids or acetoxyacetyl chloride/phthalimidoacetyl chloride 5a–e with novel α-methylene-pyrazole-carboxylate imines 4a–c using Et3N and POCl3 in refluxing toluene. All of the newly synthesized α-methylene-pyrazole carboxylate imines 4a–c and their β-lactam derivatives 6a–h have been fully characterized by spectroscopic techniques such as FTIR, NMR (1H, 13C, and 13C DEPT-135), 2D-NMR (COSY and HSQC), and elemental analyses (CHN). The cycloaddition reaction was found to be highly stereoselective leading to the exclusive formation of trans-β-lactams 6a–h and trans configuration was assigned with respect to coupling constant values of C3-H and C4-H. The novel β-lactams 6a–h bearing α-methylene-pyrazole-carboxylate ring system will serve as useful synthons for highly functionalized acids, acetohydrazides/pyrazolones, alcohols, pyrazole carboxamides, peptides, and promising biologically active agents. 相似文献
130.
Dmitrii Egorov Sadia Bari Rebecca Boll Simon Dörner Sascha Deinert Simone Techert Ronnie Hoekstra Vicente Zamudio-Bayer Rebecka Lindblad Christine Bülow Martin Timm Bernd von Issendorff J. Tobias Lau Thomas Schlathölter 《Journal of the American Society for Mass Spectrometry》2018,29(11):2138-2151
We have investigated the photoionization and photofragmentation yields of gas-phase multiply protonated melittin cations for photon energies at the K-shell absorption edges of carbon, nitrogen, and oxygen. Two similar experimental approaches were employed. In both experiments, mass selected [melittin+qH]q+ (q=2–4) ions were accumulated in radiofrequency ion traps. The trap content was exposed to intense beams of monochromatic soft X-ray photons from synchrotron beamlines and photoproducts were analyzed by means of time-of-flight mass spectrometry. Mass spectra were recorded for fixed photon energies, and partial ion yield spectra were recorded as a function of photon energy. The combination of mass spectrometry and soft X-ray spectroscopy allows for a direct correlation of protein electronic structure with various photoionization channels. Non-dissociative single and double ionization are used as a reference. The contribution of both channels to various backbone scission channels is quantified and related to activation energies and protonation sites. Soft X-ray absorption mass spectrometry combines fast energy deposition with single and double ionization and could complement established activation techniques. 相似文献