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31.
Joseph T. Hill-Cousins Sofia S. Salim Youssef M. Bakar Richard K. Bellingham Mark E. Light Richard C.D. Brown 《Tetrahedron》2014
Ring-closing metathesis (RCM) and sequential Yb(OTf)3 promoted Diels–Alder reactions of sulfamide-linked enynes proceeded selectively in one-pot to afford a series of bicyclic and tricyclic sulfamides. Excellent levels of diastereoselectivity are observed for the cycloaddition step, with only the endo-adducts being isolated. The protocol was further extended to incorporate a one-pot RCM–cross metathesis (CM)–Diels–Alder sequence, permitting rapid access to high levels of molecular complexity from simple and easily accessible precursors. 相似文献
32.
Vladimir Zaichick Sofia Zaichick 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):383-397
The variation with age of the mass fraction of 54 trace elements (Ag, Al, As, Au, B, Be, Bi, Br, Cd, Ce, Co, Cr, Cs, Dy, Er, Eu, Fe, Ga, Gd, Hf, Hg, Ho, Ir, La, Li, Lu, Mn, Mo, Nb, Nd, Ni, Pb, Pd, Pr, Pt, Rb, Re, Sb, Sc, Se, Sm, Sn, Ta, Tb, Te, Th, Ti, Tl, Tm, U, Y, Yb, Zn, and Zr) in intact nonhyperplastic prostate of 65 healthy 21–87 year old males was investigated by instrumental neutron activation analysis with high resolution spectrometry of long-lived radionuclides and inductively coupled plasma mass spectrometry. This work revealed that there is a significant tendency for an increase in Bi, Cd, Co, Fe, Hg, Sc, Sn, Th, U, and Zn (p < 0.0014) mass fraction in normal prostate from age 21 years to the sixth decade. In the sixth to ninth decades the mass fractions of almost all chemical elements investigated in nonhyperplastic prostates were maintained at approximately stable levels. Our finding of correlation between pairs of prostatic chemical element mass fractions indicates that there is a great disturbance of prostatic chemical element relationships with increasing age. 相似文献
33.
34.
Starikov FA Kochemasov GG Kulikov SM Manachinsky AN Maslov NV Ogorodnikov AV Sukharev SA Aksenov VP Izmailov IV Kanev FY Atuchin VV Soldatenkov IS 《Optics letters》2007,32(16):2291-2293
Reconstruction the phase front of a vortex laser beam is conducted by use of a Hartmann-Shack wavefront sensor. The vortex beam in the form of the Laguerre-Gaussian LG(0)(1) mode is generated with the help of a spiral phase plate. The new reconstruction technique based on measured wavefront gradients allows one to restore the singular phase surface with good accuracy, whereas the conventional least-squares approach fails. 相似文献
35.
Sofia I. Bär Madeleine Gold Sebastian W. Schleser Dr. Tobias Rehm Alexander Bär Leonhard Köhler Lucas R. Carnell Dr. Bernhard Biersack Prof. Dr. Rainer Schobert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(15):5003-5010
Three [1,3-diethyl-4-(p-methoxyphenyl)-5-(3,4,5-trimethoxyphenyl)imidazol-2-ylidene](L)gold(I) complexes, 4 a (L=Cl), 5 a (L=PPh3), and 6 a (L=same N-heterocyclic carbene (NHC)), and their fluorescent [4-(anthracen-9-yl)-1,3-diethyl-5-phenylimidazol-2-ylidene](L)gold(I) analogues, 4 b , 5 b , and 6 b , respectively, were studied for their localisation and effects in cancer cells. Despite their identical NHC ligands, the last three accumulated in different compartments of melanoma cells, namely, the nucleus ( 4 b ), mitochondria ( 5 b ), or lysosomes ( 6 b ). Ligand L was also more decisive for the site of accumulation than the NHC ligand because the couples 4 a / 4 b , 5 a / 5 b , and 6 a / 6 b , carrying different NHC ligands, afforded similar results in cytotoxicity tests, and tests on targets typically found at their sites of accumulation, such as DNA in nuclei, reactive oxygen species and thioredoxin reductase in mitochondria, and lysosomal membranes. Regardless of the site of accumulation, cancer cell apoptosis was eventually induced. The concept of guiding a bioactive complex fragment to a particular subcellular target by secondary ligand L could reduce unwanted side effects. 相似文献
36.
Suihan Feng Dr. Vibor Laketa Frank Stein Dr. Anna Rutkowska Dr. Aidan MacNamara Dr. Sofia Depner Prof. Ursula Klingmüller Dr. Julio Saez‐Rodriguez Priv.‐Doz. Dr. Carsten Schultz 《Angewandte Chemie (International ed. in English)》2014,53(26):6720-6723
Chemical dimerizers are powerful tools for non‐invasive manipulation of enzyme activities in intact cells. Here we introduce the first rapidly reversible small‐molecule‐based dimerization system and demonstrate a sufficiently fast switch‐off to determine kinetics of lipid metabolizing enzymes in living cells. We applied this new method to induce and stop phosphatidylinositol 3‐kinase (PI3K) activity, allowing us to quantitatively measure the turnover of phosphatidylinositol 3,4,5‐trisphosphate (PIP3) and its downstream effectors by confocal fluorescence microscopy as well as standard biochemical methods. 相似文献
37.
Dr. Sofia Curland Dr. Christoph Allolio Leah Javitt Shiri Dishon Ben-Ami Dr. Isabelle Weissbuch Dr. David Ehre Prof. Dr. Daniel Harries Prof. Dr. Meir Lahav Prof. Dr. Igor Lubomirsky 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15705-15709
Electrofreezing experiments of super-cooled water (SCW) with different ions, performed directly on the charged hemihedral faces of pyroelectric LiTaO3 and AgI crystals, in the presence and in the absence of pyroelectric charge are reported. It is demonstrated that bicarbonate (HCO3−) ions elevate the icing temperature near the positively charged faces. In contrast, the hydronium (H3O+) slightly reduces the icing temperature. Molecular dynamics simulations suggest that the hydrated trigonal planar HCO3− ions self-assemble with water molecules near the surface of the AgI crystal as clusters of slightly different configuration from those of the ice-like hexagons. These clusters, however, have a tendency to serve as embryonic nuclei for ice crystallization. Consequently, we predicted and experimentally confirmed that the trigonal planar ions of NO3− and guanidinium (Gdm+), at appropriate concentrations, elevate the icing temperature near the positive and negative charged surfaces, respectively. On the other hand, the Cl− and SO42− ions of different configurations reduce the icing temperature. 相似文献
38.
The task of reconstructing the system’s state from the measurements results, known as the Pauli problem, usually requires repetition of two successive steps. Preparation in an initial state to be determined is followed by an accurate measurement of one of the several chosen operators in order to provide the necessary “Pauli data”. We consider a similar yet more general problem of recovering Feynman’s transition (path) amplitudes from the results of at least three consecutive measurements. The three-step histories of a pre- and post-selected quantum system are subjected to a type of interference not available to their two-step counterparts. We show that this interference can be exploited, and if the intermediate measurement is “fuzzy”, the path amplitudes can be successfully recovered. The simplest case of a two-level system is analysed in detail. The “weak measurement” limit and the usefulness of the path amplitudes are also discussed. 相似文献
39.
Ana Sofia Almeida Brbara Silva Paula Guedes de Pinho Fernando Remio Carla Fernandes 《Molecules (Basel, Switzerland)》2022,27(7)
New psychoactive substances represent a public health threat since they are not controlled by international conventions, are easily accessible online and are sold as a legal alternative to illicit drugs. Among them, synthetic cathinones are widely abused due to their stimulant and hallucinogenic effects. To circumvent the law, new derivatives are clandestinely synthesized and, therefore, synthetic cathinones keep emerging on the drug market, with their chemical and toxicological properties still unknown. In this review, a literature assessment about synthetic cathinones is presented focusing on the recent developments, which include more than 50 derivatives since 2014. A summary of their toxicokinetic and toxicodynamic properties are also presented. Furthermore, synthetic cathinones are chiral compounds, meaning that they can exist as two enantiomeric forms which may present different biological and toxicological activities. To analyze the enantiomers, the development of enantiomeric resolution methods for synthetic cathinones is crucial. Many methods have been reported over the years that include mostly chromatographic and electromigration techniques, with liquid chromatography using chiral stationary phases being the technique of choice. This review intended to present an overview of enantioselectivity studies and enantioseparation analysis regarding synthetic cathinones, highlighting the relevance of chirality and current trends. 相似文献
40.
Sarath P. Gunasekera Sofia Kokkaliari Ranjala Ratnayake Thomas Sauvage Larissa A. H. dos Santos Hendrik Luesch Valerie J. Paul 《Molecules (Basel, Switzerland)》2022,27(5)
Dysidazirine carboxylic acid (1) was isolated from the lipophilic extract of a collection of the benthic marine cyanobacterium Caldora sp. from reefs near Fort Lauderdale, Florida. The planar structure of this new compound was determined by spectroscopic methods and comparisons between HRMS and NMR data with its reported methyl ester. The absolute configuration of the single chiral center was determined by the conversion of 1 to the methyl ester and the comparison of its specific rotation data with the two known methyl ester isomers, 2 and 3. Molecular sequencing with 16S rDNA indicated that this cyanobacterium differs from Caldora penicillata (Oscillatoriales) and represents a previously undocumented and novel Caldora species. Dysidazirine (2) showed weak cytotoxicity against HCT116 colorectal cancer cells (IC50 9.1 µM), while dysidazirine carboxylic acid (1) was non-cytotoxic. Similar cell viability patterns were observed in RAW264.7 cells with dysidazirine only (2), displaying cytotoxicity at the highest concentration tested (50 µM). The non-cytotoxic dysidazirine carboxylic acid (1) demonstrated anti-inflammatory activity in RAW264.7 cells stimulated with LPS. After 24 h, 1 inhibited the production of NO by almost 50% at 50 µM, without inducing cytotoxicity. Compound 1 rapidly decreased gene expression of the pro-inflammatory gene iNOS after 3 h post-LPS treatment and in a dose-dependent manner (IC50 ~1 µM); the downregulation of iNOS persisted at least until 12 h. 相似文献