It has been theoretically predicted that interacting electron gas suffers a negative compressibility when the electron density is sufficiently reduced. Dielectric anomaly is another expression of ...compressional instability in which the static dielectric function of electron gas changes sign from positive to negative. In a medium with a negative dielectric function, like charges can attract. Expanding fluid alkali metals are the ideal system in which such instability of electron gas can be probed via the structural response of ions. We have performed x-ray diffraction and small angle x-ray scattering measurements using synchrotron radiation for expanding fluid rubidium and cesium. On the basis of the experimental results we discuss the existence of compressional instability and dielectric anomaly in three-dimensional electron gas.
Crosstalk of signaling pathways is critical during metazoan development and adult tissue homeostasis. Even though the transforming growth factor-beta (TGFβ) transduction cascade is rather simple, in ...vivo responsiveness to TGFβ ligands is tightly regulated at several steps. As such, TGFβ represents a paradigm for how the activity of one signaling system is modulated by others. Here, we report an unsuspected regulatory step involving Dishevelled (Dvl) and Par1b (also known as MARK2). Dvl and Par1b cooperate to enable TGFβ/bone morphogenetic protein (BMP) signaling in Xenopus mesoderm development and TGFβ responsiveness in mammalian cells. Mechanistically, the assembly of the Par1b/Dvl3/Smad4 complex is fostered by Wnt5a. The association of Smad4 to Dvl/Par1 prevents its inhibitory ubiquitination by ectodermin (also known as transcriptional intermediary factor 1 gamma or tripartite motif protein 33). We propose that this crosstalk is relevant to coordinate TGFβ responses with Wnt-noncanonical and polarity pathways.
Aims: To obtain strong, carbon source‐inducible promoters useful for industrial applications of Corynebacterium glutamicum.
Methods and Results: DNA microarray and qRT‐PCR enabled identification of ...the promoters of cgR_2367 (malE1) and cgR_2459 (git1) as strong, maltose‐ and gluconate‐inducible promoters, respectively, in C. glutamicum. Promoter probe assays revealed that in the presence of the inducing sugars, PmalE1 and Pgit1, respectively, facilitated 3·4‐ and 4·2‐fold increased β‐galactosidase activities compared to the same activity induced by glucose. In addition, PmalE1 was not functional in Escherichia coli, in which Pgit1 function was repressible, which enabled the cloning of a hitherto ‘difficult‐to‐clone’ heterologous gene of a lignocellulolytic enzyme, whose secretion was consequently induced by the carbon sources.
Conclusions: PmalE1 and Pgit1 are strong, carbon source‐inducible promoters of C. glutamicum whose characteristics in E. coli are integral to the secretion ability of C. glutamicum to secrete lignocellulolytic enzyme.
Significance and Impact of the Study: Corynebacterium glutamicum, like its counterpart industrial workhorses E. coli and Bacillus subtilis, does exhibit strong, carbon source‐inducible promoters, and the functionality of two of which was demonstrated in this study. While this study may be most relevant in the ongoing efforts to establish technologies of the biorefinery, it should also be of interest to general microbiologists exploring the versatility of industrial micro‐organisms. In so doing, the study should impact future advances in industrial microbiology.
The dynamic structure factor of molten CsCl has been measured at low momentum transfer, 1.4 nm-1 < =Q < 33 nm-1, using high-resolution inelastic x-ray scattering. The longitudinal acoustic mode ...disperses 1.7 times faster than the adiabatic sound velocity and its linewidth increases following the Q2 law as predicted by the hydrodynamics. However, the linewidth is a factor of seven smaller than the estimation using the linewidths obtained from Brillouin light scattering. The large speed-up and the significant narrowing of the collective mode, which can be related to each other by a recently presented viscoelastic theory, must arise from the intrinsic nature of molten alkali chlorides. Furthermore in comparison with the previous results for molten NaCl and KCl, the apparent sound velocity is found to be approximately scaled by the inverse of the square-root of the effective mass among these molten salts.
Sub‐seabed geological storage of CO2 in the form of gas hydrate is attractive because clathrate hydrate stably exists at low temperature and high pressure, even if a fault occurs by diastrophism like ...a big earthquake. For the effective design of the storage system it is necessary to model the formation of CO2‐hydrate. Here, it is assumed that the formation of gas hydrate on the interface between gas and water consists of two stages: gas diffusion through the CO2‐hydrate film and consequent CO2‐hydrate formation on the interface, between film and water. Also proposed is the presence of a fresh reaction interface, which is part of the interface between the gas and aqueous phases and not covered with CO2‐hydrate. Parameters necessary to model the hydrate formation in sand sediment are derived by comparing the results of the present numerical simulations and the measurements in the literature.
A mathematical model for the formation of CO2‐hydrate in sand sediment is proposed for sub‐seabed geological storage of CO2 in the form of gas hydrate, considering gas diffusion through the CO2‐hydrate film and the presence of a fresh reaction interface. CO2‐hydrate formation was numerically simulated by solving a heat transfer equation.
We propose a new method for multi-scale reverse Monte Carlo (RMC) modeling of small-angle scattering data using reverse mapping from coarse-grained particles to atoms in cases where scale separation ...cannot be assumed. For efficient RMC analysis for small-angle scattering data, it is important to determine a large scale structure with the lowest possible computing cost. In order to find this large scale structure, a method using coarse-grained particles instead of atoms is suitable. As our first example, we examine the structure of expanded fluid Hg near the critical point. For this system, small-angle x-ray scattering (SAXS) data and wide-angle x-ray diffraction data (XRD) are observed in the same thermodynamic state. First, RMC analysis using coarse-grained particles for SAXS data is performed. Second, RMC analysis for SAXS and XRD data is performed with the replacement of a coarse-grained particle by an ad hoc cluster of several Hg atoms. In the present study, we have determined that the size of one coarse-grained particle corresponds to ten Hg atoms. The number density for the coarse-grained particles is set to one-tenth the actual number density of atoms and the cutoff length is three times (6.9 Å) that of Hg atoms (2.3 Å). As a result, this approach is found to be successful and the computing cost of RMC analysis can be reduced.
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