Electron-attachment resonances of glycine zwitterions from quantum scattering calculations: modeling macrosolvation effects

A computational study of the quantum dynamics for low-energy electrons scattered by the isolated zwitterionic species of the glycine molecule is carried out using a model interaction potential described in the main text. The macroscopic effects of water solvation on the target molecule in the electron scattering problem are described through a continuum polarizable model (CPCM) which modifies the target molecular structure. In such a way, realistic molecular orbitals depicting the glycine zwitterion in solution are used to model the electron-molecule interaction. The results of the calculations indicate the presence of five different transient negative ions (TNIs) formed at energies from the threshold and up to about 6 eV. Although no nuclear motion was explicitly considered in the ensuing decay processes, the analysis of the nodal structures and density distributions for the resonant excess electron wavefunctions over the molecular space suggests possible anionic fragmentations that produce (Gly-H)-, H-, -CO2-, and -NH3. The likely consequences of such releases into the medium are briefly discussed.     

Differentiation of human bone marrow stem cells into cells with a neural phenotype: diverse effects of two specific treatments

Background  

It has recently been demonstrated that the fate of adult cells is not restricted to their tissues of origin. In particular, it has been shown that bone marrow stem cells can give rise to cells of different tissues, including neural cells, hepatocytes and myocytes, expanding their differentiation potential.     

Evidence for non-yrast states in 254No

Evidence for the decay of non-yrast states in ²⁵⁴No has been observed for the first time in an experiment performed at the University of Jyv?skyl?. The experiment employed the JUROGAM array of germanium detectors coupled to the gas-filled recoil separator RITU and the focal-plane spectrometer GREAT. The ground-state rotational band has been tentatively extended up to a spin of 24ℏ and has a smoothly behaving dynamical moment of inertia. It is speculated that the observation of high-energy γ-rays is due to the decay of a K = 3 band-head state.     

Controllability method for acoustic scattering with spectral elements

We formulate the Helmholtz equation as an exact controllability problem for the time-dependent wave equation. The problem is then discretized in time domain with central finite difference scheme and in space domain with spectral elements. This approach leads to high accuracy in spatial discretization. Moreover, the spectral element method results in diagonal mass matrices, which makes the time integration of the wave equation highly efficient. After discretization, the exact controllability problem is reformulated as a least-squares problem, which is solved by the conjugate gradient method. We illustrate the method with some numerical experiments, which demonstrate the significant improvements in efficiency due to the higher order spectral elements. For a given accuracy, the controllability technique with spectral element method requires fewer computational operations than with conventional finite element method. In addition, by using higher order polynomial basis the influence of the pollution effect is reduced.     

Simultaneous detection of three antiviral and four antibiotic compounds in source‐separated urine with liquid chromatography

An analytical method for the simultaneous screening of three antiviral agents (nevirapine, zidovudine, lamivudine), four antibiotics (sulfamethoxazole, trimethoprim, ciprofloxacin, rifampicin) and one reference compound (carbamazepine) in human urine was developed. Separation was achieved with a Kinetex XB‐C₁₈ (75 × 4.6 mm, 2.6 μm) column after the extraction of pharmaceuticals from urine with SPE. Gradient elution with a mobile phase consisting of acetonitrile and 10 mM KH₂PO₄ (pH 2.5), and diode array detection with monitoring at 210 and 264 nm was applied. The developed method was validated in terms of selectivity, linearity, stability and sensitivity. Repeatability (n = 3) and between‐day precision (n = 3) revealed RSD <5%. The detection limits were estimated as 0.02–0.54 g/L (depending on compound). The method was validated for human urine and successfully applied to the simultaneous quantification of selected compounds. Strata‐X cartridges provided good recoveries ranging from 81 to 109%. The limits of detection for urine varied between 0.04 and 1.61 g/L. The method is suitable for the fast determination of selected pharmaceuticals from source‐separated urine samples for further environmental risk assessment and degradation potential evaluation. It provides a way to enhance safe nutrient recycling from wastewater streams and promotes the safe use of urine as fertiliser.     

Ru2+ complexes comprising terpyridine ligands appended with terthiophene chromophores: energy transfer and energy reservoir effect

Two Ru(2+) complexes containing terpyridine ligands appended with terthiophene units connected by a methyleneoxy or an alkynyl bridge show very different luminescent behaviours: the former is non-luminescent at 298 K owing to a photoinduced energy transfer process to the terthiophene moiety, while the latter exhibits an extraordinary long excited state lifetime because of an energy reservoir effect.     

Conformational analysis and UV/Vis spectroscopic properties of a rotaxane-based molecular machine in acetonitrile dilute solution: when simulations meet experiments

A reduced form of a synthetic hydrogen-assembled molecular shuttle for nano-technological applications has been investigated by molecular dynamics simulations and density functional theory calculations. It is composed by a benzylic amide macrocycle mechanically locked onto a thread in acetonitrile solution. Classical sampling indicates, in agreement with experimental findings, that in equilibrium condition at 298 K the macrocycle and the naphthalimide radical anion moiety within the thread strongly interact forming four strong OCN-H-O=CNR hydrogen bonds. Simulations also revealed that the geometry of the supramolecular assembly reversibly oscillates between unfolded and folded conformations, with the latter characterized by an electrostatic hook involving the succinamide end group and the macrocycle itself. Finally, the simulated UV-Vis absorption spectra for free and complexed reduced naphthalimide quantitatively confirm that the transient spectroscopic change experimentally used as a probe for monitoring the translational motion of the macrocycle, from succinamide to naphthalimide stations, accompanying the selective electrochemical reduction.     

On binary linear <Emphasis Type="Italic">r</Emphasis>-identifying codes

A subspace C of the binary Hamming space F ⁿ of length n is called a linear r-identifying code if for all vectors of F ⁿ the intersections of C and closed r-radius neighbourhoods are nonempty and different. In this paper, we give lower bounds for such linear codes. For radius r =  2, we give some general constructions. We give many (optimal) constructions which were found by a computer search. New constructions improve some previously known upper bounds for r-identifying codes in the case where linearity is not assumed.