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The solvation of alkali and halide ions in the aqueous environment has been a subject of intense experimental and theoretical research with multidisciplinary interests; yet, a comprehensive molecular-level understanding has still not been obtained. In recent years, electron spectroscopy has been increasingly applied to study the electronic and structural properties of aqueous ions with implications, especially in atmospheric chemistry. In this work, we report core and valence level (Cl 2p, Cl 3p, and K 3p) photoelectron spectra of the common alkali halide, KCl, doped in gas-phase water clusters in the size range of a few hundred water molecules. The results indicate that the electronic structure of these nanosolutions shows a distinct character from that observed at the liquid–vapor interface in liquid microjets and ambient pressure setups. Insights are provided into the unique solvation properties of ions in a nanoaqueous environment, emerging properties of bulk electrolyte solutions with growing cluster size, and sensitivity of the electronic structure to varying solvation configurations.

Charge transfer processes between weakly bound entities play an important role in various chemical and biological environments. In this combined experimental and theoretical work, we investigate the nature of charge-transfer processes in homogeneous atomic and heterogeneous atomic-molecular clusters. Our results reveal fundamentally different processes to be at play in pure argon clusters compared to mixed argon-nitrogen systems: We demonstrate that the former species decay via photon-mediated charge transfer while a nonradiative direct process is found dominant in the atomic-molecular cases. Our results are of general interest for studies on charge redistribution in more complex and biologically relevant samples where molecules are involved.

The photoelectron circular dichroism (PECD) of the O 1s-photoelectrons of trifluoromethyloxirane(TFMOx) is studied experimentally and theoretically for different photoelectron kinetic energies. The experiments were performed employing circularly polarized synchrotron radiation and coincidentelectron and fragment ion detection using Cold Target Recoil Ion Momentum Spectroscopy. The corresponding calculations were performed by means of the Single Center method within the relaxed-core Hartree-Fock approximation. We concentrate on the energy dependence of the differential PECD of uniaxially oriented TFMOx molecules, which is accessible through the employed coincident detection. We also compare results for differential PECD of TFMOx to those obtained for the equivalent fragmentation channel and similar photoelectron kinetic energy of methyloxirane (MOx), studied in our previous work. Thereby, we investigate the influence of the substitution of the methyl-group by the trifluoromethyl-group at the chiral center on the molecular chiral response. Finally, the presently obtained angular distribution parameters are compared to those available in literature., 6 figs

Advances in implant design, patient familiarity, and surgeon experience have led to a large cohort of patients undergoing total ankle replacement (TAR). Unfortunately, early or late failure can result from soft tissue-related wound problems, deep infection, or technical error in implantation. When a TAR becomes infected, treatment remains controversial with no level 1 evidence to support management. Individual patient characteristics are important when determining the treatment approach to the infected TAR as soft tissue coverage, patient comorbidities, and the ultimate surgical goal of the patient need to be taken into account. Salvage of an infected TAR will consist of eradication of infection, obtaining soft tissue coverage and maintaining function of the limb. Treatment strategies described in the literature consist of irrigation and debridement with or without polyethylene exchange, one-stage revision arthroplasty, and two-stage revision arthroplasty with antibiotic cement spacer. Permanent antibiotic cement spacer has been infrequently reported in the literature; however it does have a significant role in the treatment approach to the failed TAR. There are instances where patient morbidity, significant bone loss, or prolonged recovery severely limit a patient’s appetite to undergo further attempts at implant salvage. In cases where ankle fusion or revision arthroplasty is not within the goals of the patient or surgeon, permanent polymethyl methacrylate (PMMA) antibiotic-impregnated spacer can assist the patient in ultimate limb retention following the devastating complications associated with an infected TAR.

Electronic excitations in the valence shell of Ne clusters were studied by fluorescence spectroscopy. The measured fluorescence excitation functions contain information about the nature and number of excitonic states and the mean cluster size of the produced size distribution. Mean cluster sizes were determined by comparing surface and bulk contributions using a multidimensional fitting algorithm, with good agreement to commonly used scaling laws. The influence of different size distributions, which were not considered in previous investigations, on homogeneous noble gas cluster jets is implemented in the proposed model. The present work is the first approach using fluorescence spectroscopy for the determination of the mean size of Ne cluster jets created by supersonic expansion.

Physical review / X 10(4), 041056 (2020). doi:10.1103/PhysRevX.10.041056, The nature of transient electronic states created by photoabsorption critically determines the dynamics of the subsequently evolving system. Here, we investigate K-shell photoionized atomic neon by absorbing a second photon within the Auger-decay lifetime of 2.4 fs using the European XFEL, a unique high-repetition-rate, wavelength-tunable x-ray free-electron laser. By high-resolution electron spectroscopy, we map out the transient Rydberg resonances unraveling the details of the subsequent decay of the hollow atom. So far, ultra-short-lived electronic transients, which are often inaccessible by experiments, were mainly inferred from theory but are now addressed by nonlinear x-ray absorption. The successful characterization of these resonances with femtosecond lifetimes provides the basis for a novel class of site-specific, nonlinear, and time-resolved studies with strong impact for a wide range of topics in physics and chemistry., Published by APS, College Park, Md.

31st International Conference on Photonic, Electronic, and Atomic Collisions, ICPEAC XXXI, Caen Normandy, France, 23 Jan 2019 - 30 Jan 2019; Journal of physics / Conference Series 1412, 112009 (2020). doi:10.1088/1742-6596/1412/11/112009, (X-ray) free-electron lasers are employed to site specifically interrogate atomic fragments during ultra-fast photolysis of chiral molecules via time-resolved photoelectron circular dichroism., Published by IOP Publ., Bristol

Synopsis Photoelectron circular dichroism (PECD) was determined for O(1s) photoionization of methyloxirane (C3H6O) and trifluoro-methyloxirane (C3H3F3O). Several electron energies above the threshold were chosen to compare the partially fixed-in-space electron distributions.

Synopsis Results from the first soft X-ray user experiment at the European XFEL on nonlinear photon-matter interaction will be presented. Angle-resolved electron time-of-flight spectroscopy employed at the AQS (Atom-ic-like Quantum Systems) endstation of the SQS (Small Quantum Systems) instrument reveals insight into the character of resonances in highly transient, core ionized neon ions, i.e. Ne+ 1s12s22p6 → Ne+* 1s02s22p6np, together with their respective relaxation dynamics. Enabled by the unique properties of the European XFEL, novel perspectives on efficient nonlinear spectroscopy will be discussed.

We combine a quantum dynamical propagator that explicitly accounts for quantum mechanical time ordering with optimal control theory. After analyzing its performance with a simple model, we apply it to a superconducting circuit under so-called Pythagorean control. Breakdown of the rotating-wave approximation is the main source of the very strong time-dependence in this example. While the propagator that accounts for the time ordering in an iterative fashion proves its numerical efficiency for the dynamics of the superconducting circuit, its performance when combined with optimal control turns out to be rather sensitive to the strength of the time-dependence. We discuss the kind of quantum gate operations that the superconducting circuit can implement including their performance bounds in terms of fidelity and speed., 16 pages, 11 figures

Objective: Intestinal damage of neonates with gastroschisis is thought to be attributed to prolonged exposure to the toxic environment of the amniotic fluid. Amnioexchange/infusion has been a proposed method to improve bowel quality. The aim of the current study was to design an in vitro model to determine the volume and number of amnioexchanges needed to achieve a predetermined reduction in a solute contained within the original concentration of amniotic fluid. Methods: We used a predetermined volume of normal saline to serve as the model for the amniotic cavity and the chloride anion as the surrogate for the noxious agent. Volumes of 250, 500, and 750 ml were used to represent the amniotic volume at different gestational ages. We performed a series of exchanges based on our calculated formula for each respective volume. The Student t test was used to calculate the differences between our expected and observed mean chloride concentrations (p < 0.05 = significance). Results: The mean baseline chloride concentration was 100 mmol/l for each volume. Our formula overestimated the number of exchanges needed to reach a 75% reduction in chloride concentration for each volume, but this was not statistically significantly different from the observed number of exchanges (p < 0.05). Conclusion: Our formula required a correction factor of 3 or 4 fewer exchanges to obtain the desired 75% reduction in chloride concentration. It may be useful when investigations to study amnioexchange are undertaken for the treatment of fetuses with gastroschisis.

A new model is presented for a reflector producing a shaped narrow beam when illuminated by a point feed. The deviation from an idealised (Dunbar) model which has zero beam width in the geometrical optics approximation is regulated by a single arbitrary function tau , introduced to enhance the physical optics performance. In terms of tau , the phase distribution on a plane aperture is readily computed. Reflector profiles are then calculated by integration along the characteristics of a first order non-linear partial differential equation, leading to explicit formulae involving only ordinary quadratures. Initial data arises naturally on the central-section curve. It is shown that for continuous reflectors a well-known design due to Brunner (1971), frequently used in surveillance radar, is mathematically inconsistent.

A uniqueness theorem is presented for reflector mappings in the complex plane. These arise in geometrical optics, in the synthesis of a reflector surface to produce a ray beam with specified angular distribution of energy when illuminated by a non-isotropic point-source. The mappings may be represented as solutions of a nonlinear boundary-value problem involving the Monge-Ampère equation. When the equation is elliptic there are at most two solutions, provided that either the incident or far-field ray cone satisfies a convexity condition, which is always the case if one cone is circular. The result has practical application to the design of single and offset dual reflectors used for radar and communications purposes.

The reflexion of outward travelling cylindrical gravitational waves by a thin cylindrical shell of matter is discussed. The shell is regarded as a surface distribution, and it is shown that if it is perfectly rigid, total reflexion occurs. Quasi-periodic incident waves are found to lead to a completely periodic standing wave state between the reflector and a central wave-source, the field outside the system remaining static. In the treatment of standing waves the components of the stress-energy tensor in the shell are determined and the construction for a model source is given.

The detergency and redeposition characteristics of several modern fabrics were compared under laboratory and home-laundering conditions. Good correlation was found between data from laboratory-controlled practical washing and home laundry although washing in the home was uniformly poorer than in the laboratory. Polyester-containing fabrics tend to gray by redeposition more than the other fabrics investigated, and the new Permanent-Press fabrics seem more susceptible to redeposition than their untreated counterparts. A systematic screening of factors affecting the performance of these fabrics in the home laundry indicates that detergent underusage is the major factor for the failure of polyesters to perform as well as cotton in either laboratory or practical laundry screening.

If two empty regions of space-time are entirely separated by matter, little information of the nature of one region can be gained by knowledge of the other. Examples of a hollow Schwarzschild sphere and a hollow static torus are considered. In the first of these, it is shown that the size of the flat interior is not at all limited by the smallness of the Schwarzschild mass constant, the outer spherical boundary, or the condition that the sphere be constructed only of matter of positive density with positive stress-energy scalar.

Summary The observed linear relation between bulk modulus and pressure in the Earth is used to simplify the equations of hydrostatic equilibrium through the introduction of homology invariant variables. These variables, introduced previously for the discussion of simple stellar models, reduce the integrations to the fitting of curves belonging to a one-parameter family and so enable many models to be examined with comparative ease. Examples of the use of the method are given, particularly in relation to the structure of Mars and Venus.

A device making use of the linearity of one of the field equations for Rosen’s cylindrically symmetric metric is employed to demonstrate a correspondence between some outgoing toroidal gravitational waves and imploding-exploding cylindrical waves. An exact form of axially symmetric metric for a smooth toroidal pulse in the region ｜ z ｜ < t (in coordinates which approximate to cylindrical polars when the field is weak) is constructed, and extensions to the region ｜ z ｜ < t are considered. The solution remains valid throughout the reflexion of the wave as it meets itself on the symmetry axis, and displays this process clearly. As a particular example, a solution of Weber & Wheeler for a non-singular cylindrical pulse is converted into one for a time-symmetric toroidal pulse, and the distant field at the moment of time-symmetry is briefly examined.

Known cylindrical wave solutions of the free-space gravitational field equations are superimposed on a static field and extended to the interior of a generating cylinder of matter. It is shown that the waves propagate energy. The interior and exterior field of a static cylinder of approximately constant density is obtained.

A construction is given for an exact solution of Einstein’s empty space-time field equations representing an axially sjonmetric pulse wave with the properties that (i) the wave front is a sphere, outside of which all space-time is flat; (ii) a finite, expanding line singularity forms the axial diameter of this sphere. Because of (i), the solution would need to be generalized before a physical source could be introduced. The presence of radiation is confirmed by the fact that at a great distance from the centre of the wave the Riemann tensor is asymptotically of Petrov’s canonical type II (with vanishing scalar invariants).

Further properties of a vacuum metric obtained in an earlier paper, representing a spherical-fronted gravitational wave (which, however, possesses cylindrical symmetry) are derived. This metric is constructed by introducing ‘bending terms’ into Rosen’s metric for cylindrical waves. The way the transition occurs from properties characteristic of cylindrical waves to those of spherical waves is examined. The asymptotic behaviour of the optical parameters and the null tetrad components of the Weyl (Riemann) tensor along an outgoing null geodesic is determined. An interpretation of the axial singularity is given by comparison with an analogous feature in classical electromagnetic wave propagation.

Polyvinylene carbonate is a linear polymer which can be dissolved with saponification in cold alkali. After precipitation the resultant amorphous polyvinylene glycol can only be dissolved in fused urea. Vinylene carbonate (M1)–vinyl acetate (M2) copolymers are higher melting than polyvinylacetate, and at 55° the reactivity ratios are r1 = 0.0579, r2 = 3.71. Expressions are derived relating periodate consumption and formic acid formation by hydrolyzed vinylene carbonate copolymers to the number-average sequence lengths predicted by copolymerization theory. Periodate consumption by the homopolymer and copolymers is complicated by the overoxidation of the intermediate malondialdehyde to carbon dioxide. When this side reaction is taken into account, periodate consumption and formic acid liberation are in reasonably good semi-quantitative agreement with theoretical predications of number-average sequence length.

The geometry of an extended region of space-time is not fully determined by the vanishing of the Riemain curvature tensor. This suggests the possible existence of a non-trivial gravitational field where space-time is flat. Two examples of such fields are considered with reference to their sources. It is quite familiar that certain Riemannian spaces, such as the plane, cylinder and cone, are locally isometric. They differ only in their topology. Little attention, however, has yet been paid to an analogous situation concerning space-times in general relativity. In this paper it is shown that Einstein's gravitational field equations admit exact solutions whose empty regions are locally flat (in that the Riemann tensor vanishes everywhere), but for which there exists no universal Minkowskian co-ordinate system. Two examples are given, and an investigation of geodesics shows that each corresponds to a non-trivial gravitational field. The first example relates to a cylindrically symmetric field, for which a model source with uniform positive density is constructed. This field is important to the problem of cylindrical gravitational waves. In the second example a toroidal source is assumed, although here it appears that no physically sensible interior solution is possible. Nevertheless, the example is interesting as one in which, for topological reasons, the metric of a solution for the exterior of a finite source does not determine the field completely.

Various definitions of uniform acceleration are possible in relativity theory. Two of these are considered with particular reference to their physical realizations.

It is well known that there is no static axisymmetric two-body solution of Einstein's gravitational field equations, if it is assumed that the bodies are separated in a certain definite sense. In this paper it is shown, by the construction of a complete physically sensible model, that static two-body solutions do exist for systems in which one body is hollow and contains the other. The stability of the particular system described is briefly discussed.