Iron works: A ferrocene derivative, one of a series of ferronucleosides designed by the Tucker group, shows micromolar toxicity in a range of cancer cell lines. Their latest research shows the importance to activity of having arms in adjacent positions, with the 1,1’-regioisomer much less active in bone cancer cell lines. On the other hand, N- or O-methylation has much less of an effect; this rules out a conventional mechanism of action for a nucleoside, giving further weight to one that involves the iron centre. More information can be found in the full paper by N. J. Hodges, J. H. R. Tucker et al.
Reversible intramolecular cyclization reactions to form crown ethers are possible with photoactive anthracene derivatives containing two binding sites (see scheme). Different chemical inputs in the form of HgCl2 and Na+ ions result in changes in the efficiency and rate of the forward and reverse processes.
The ability to discriminate between epigenetic variants in DNA is a necessary tool if we are to increase our understanding of the roles that they play in various biological processes and medical conditions. Herein, it is demonstrated how a simple two-step fluorescent probe assay can be used to differentiate all three major epigenetic variants of cytosine at a single locus site in a target strand of DNA.
Planar chirality associated with the ferrocene in ferrocenyl oximes and hydrazones bearing chiral auxiliaries effectively competes with or overrides the normally excellent stereocontrol afforded by the auxiliary in determining the diastereoselectivity of addition to the C=N bond.
Shallow thermal donors (STDs), generated in Czochralski silicon, annealed at 470\ifmmode^\circ\else\textdegree\fi{}C in a hydrogen plasma, and detected by their infrared (IR) electronic absorption, have ground states that shift slightly (\ensuremath{\sim}0.1 ${\mathrm{cm}}^{\ensuremath{-}1}$) to smaller binding energies, when deuterium is introduced instead of hydrogen, demonstrating the presence of a hydrogen atom in the donor core. No other IR spectrum is detected apart from that from neutral double thermal donors (TDs). The same optical transitions are observed in three annealed samples given a preheat treatment in water vapor. These latter samples show the NL10 electron-paramagnetic-resonance (EPR) spectrum, recently attributed to hydrogen passivated TDs. The relative strengths of the EPR NL10 spectra correlate with those of the STD IR spectra, providing a strong indication that both spectra arise from the same defects.
The introduction of cationic polyelectrolytes as cellular adherents has significantly advanced the preparation of cervical scrape specimens for automated cell scanning and has also provided an efficient technique for the preparation of cell monolayers of other cytologic specimens, e.g., breast cyst fluids, urines and serous effusions, for diagnostic cytopathology. Variable thickness of cell preparation and cell overlap have both been resolved by laying cells onto glass slides coated with the cationic polyelectrolyte poly-L-lysine. We have determined the optimal conditions for pH, molecular weight, concentration and temperature for the application of poly-L-lysine as a cell-to-slide adhesive.
Boron-doped, float zone silicon has been hydrogenated at C and then quenched to room temperature. Infrared absorption measurements of the samples in their as-quenched state and following anneals at C reveal the vibrational mode from H-B pairs, together with the line that we have assigned to the vibrational mode of isolated hydrogen molecules . Annealing leads to irreversible increases in the concentrations of H-B pairs and decreases in the concentration of centres. The results imply that molecules diffuse to boron acceptors and that there is subsequent dissociation of these molecules with the formation of H-B pairs. The measurements confirm an earlier proposal that `hidden hydrogen' present in such samples is in the form of isolated molecules.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Boron-doped Czochralski silicon samples with [B]∼1017 cm−3 have been heated at various temperatures in the range 800–1300 °C in an atmosphere of hydrogen and then quenched. The concentration of [H-B] pairs was measured by infrared localized vibrational mode spectroscopy. It was concluded that the solubility of atomic hydrogen is greater than [Hs] = 5.6 × 1018 exp( − 0.95 eV/kT)cm−3 at the temperatures investigated.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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