Note on the quantum displacement of the critical point

The quantum corrections to the law of corresponding states are studied by calculating the critical pressure, temperature, and density to first order in Planck's constanth on an exactly soluble model. The ratio of the critical parameters to the corresponding classical values are found to be (p _c/p _c ⁰)^1/2=_c/_c ⁰ = T_c/T_c ⁰ = 1–0.67, with=h _c ^1/3(mkT _c)^–1/2. The critical ratio is independent ofh to first order. The results are compared with critical data for noble gases and hydrogen isotopes.     

Measurement of spatial gain distribution for a neonlike germanium 19.6-nm laser

We measure the transverse spatial distribution of the gain region for the 19.6-nm neonlike germanium laser line by use of a short amplifier, which is backlit by a longer laser, both of which are created by illumination of a germanium slab target with a series of short 100-ps pulses from the Nova laser. The backlighting technique enables us to reduce greatly the refraction effects that dominated previous imaging experiments and made direct gain measurements impossible. Measurements are made with a two-dimensional high-resolution spatial-imaging diagnostic, and simulations of the gain are compared with experiments.     

Z-dependences of atomic parameters of autoionization states of two-electron systems

On the bais of two programs, calculations are carried out for energies, probabilities of radiative transitions and nonradiative decays, and lifetimes of levels of two-electron systems 2l.4l. The results of the two calculations are compared for a wide range of Z. Possible channels of radiative transitions and nonradiative decays are discussed. Their relative contribution to the total probability is evaluated. This evaluation is compared with data obtained by calculations, on the basis of which a conclusion is made about the contribution of correlation and relativistic effects. The Z-dependences are investigated for each of the parameters under consideration. A comparison is made with the results of other calculations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 55–72, August, 1990.     

Preparation and Characterization of Binder for Inorganic Composites Made from Amorphous Mineral Raw Material

The preparation and characterization of a composite binder made through a sol-gel route from an amorphous mineral raw material has been studied. The amorphous mineral raw material is alumino-silicate based but contains also alkaline earth and some transition metal oxides. A stable sol can be prepared by dissolving the raw materials in formic acid. The drying and heat treatment of the subsequent gel has been studied by thermogravimetry, nuclear magnetic resonance, infrared spectroscopy as well as X-ray diffraction studies. The different constituents of the raw material have shown to play a major role during the drying and heat treatment of the gels. The binding effect of the binder was evaluated to be good by studying paper-binder composites as well as wetting properties.     

Resonant bound-free contributions to Thomson scattering of X-rays by warm dense matter

Recent calculations [Nilsen et al. arXiv:1212.5972] predict that contributions to the scattered photon spectrum from 3s and 3p bound states in chromium (Z = 24) at metallic density and T = 12 eV resonate below the respective bound-state thresholds. These resonances are shown to be closely related to continuum lowering, where 3d bound states in the free atom dissolve into a resonant l = 2 partial wave in the continuum. The resulting d-state resonance dominates contributions to the bound-free dynamic structure function, leading to the predicted resonances in the scattered X-ray spectrum. Similar resonant features are shown to occur in all elements in the periodic table between Ca and Mn (20 ≤ Z ≤ 25).     

The effect of bound states on X-ray Thomson scattering for partially ionized plasmas

X-ray Thomson scattering is being developed as a method to measure the temperature, electron density, and ionization state of high energy density plasmas such as those used in inertial confinement fusion. X-ray laser sources have always been of interest because of the need to have a bright monochromatic X-ray source to overcome plasma emission and eliminate other lines in the background that complicate the analysis. With the advent of the X-ray free electron laser (X-FEL) at the SNAL Linac Coherent Light Source (LCLS) and other facilities coming online worldwide, we now have such a source available in the keV regime. An important challenge with X-ray Thomson scattering experiments is understanding how to model the scattering for partially ionized plasmas. Most Thomson scattering codes used to model experimental data greatly simplify or neglect the contributions of the bound electrons to the scattered intensity. In this work we take the existing models of Thomson scattering that include elastic ion–ion scattering and inelastic electron–electron scattering and add the contribution of bound electrons in the partially ionized plasmas. Except for hydrogen plasmas, most plasmas studied today have bound electrons and it is important to understand their contribution to the Thomson scattering, especially as new X-ray sources such as an X-FEL will allow us to study much higher Z plasmas. To date, most experiments have studied hydrogen or beryllium plasmas. We first analyze existing experimental data for beryllium to validate the code. We then consider several higher Z materials such as Cr and predict the existence of additional peaks in the scattering spectrum that require new computational tools to understand. For a Sn plasma, we show that bound contributions change the shape of the scattered spectrum in a way that would change the plasma temperature and density inferred from experiment.     

Mutational analysis of the enterocin favorskii biosynthetic rearrangement

[reaction: see text] A mutational analysis of the enterocin biosynthesis genes revealed that the putative oxygenase and the methyltransferase gene products EncM and EncK, respectively, jointly catalyze a biosynthetic Favorskii-like rearrangement. Inactivation of either gene terminated enterocin production and caused the accumulation of four nonrearranged, nonmethylated polyketides. The structure elucidation of the new wailupemycins E-G is reported.     

Objective acceleration for unconstrained optimization

Acceleration schemes can dramatically improve existing optimization procedures. In most of the work on these schemes, such as nonlinear generalized minimal residual (N‐GMRES), acceleration is based on minimizing the ?₂ norm of some target on subspaces of ${\mathbb{R}}^n$. There are many numerical examples that show how accelerating general‐purpose and domain‐specific optimizers with N‐GMRES results in large improvements. We propose a natural modification to N‐GMRES, which significantly improves the performance in a testing environment originally used to advocate N‐GMRES. Our proposed approach, which we refer to as O‐ACCEL (objective acceleration), is novel in that it minimizes an approximation to the objective function on subspaces of ${\mathbb{R}}^n$. We prove that O‐ACCEL reduces to the full orthogonalization method for linear systems when the objective is quadratic, which differentiates our proposed approach from existing acceleration methods. Comparisons with the limited‐memory Broyden–Fletcher–Goldfarb–Shanno and nonlinear conjugate gradient methods indicate the competitiveness of O‐ACCEL. As it can be combined with domain‐specific optimizers, it may also be beneficial in areas where limited‐memory Broyden–Fletcher–Goldfarb–Shanno and nonlinear conjugate gradient methods are not suitable.