Molecular dynamics simulations for human CAR inverse agonists

Constitutive androstane receptor (CAR), along with pregnane x receptor (PXR), is an important metabolic sensor in the hepatocytes. Like all other nuclear receptors (NRs), CAR works in concert with coregulator proteins, coactivators, and corepressors which bind to the NRs. The main basis for the receptor to distinguish between coactivators and corepressors is the position of the C-terminal helix 12 (H12), which is determined by the bound NR ligand. CAR, having constitutive activity, can be repressed or further activated by its ligands. Crystal structure of human CAR bound to an agonist and a coactivator peptide is available, but no structural information on an inverse agonist-bound human CAR and a corepressor exists. In our previous molecular dynamics (MD) studies, no corepressor peptide was included. Therefore, probably due to the strong interactions which keep the relatively short H12 of CAR in the active position, the structural changes elicited by inverse agonists were very subtle, and H12 of CAR seemed to more or less retain its active conformation. Here, we have run a series of MD simulations to study the movement of H12 in the presence of both activating and repressing ligands as well as a corepressor peptide. The presence of the corepressor on the coregulator surface of CAR induced a clear shift of H12 of the inverse agonists-bound CAR. In general, H12 moved toward H10 and not away from the ligand binding domain, as seen in some other NRs. However, H12 of CAR is short enough that this movement seems to be adequate to accommodate the binding of the corepressor.     

Reactions of Beryllium Halides in Liquid Ammonia: The Tetraammineberyllium Cation [Be(NH3)4]2+, its Hydrolysis Products,and the Action of Be2+ as a Fluoride‐Ion Acceptor

The first structural characterization of the text‐book tetraammineberyllium(II) cation [Be(NH₃)₄]²⁺, obtained in the compounds [Be(NH₃)₄]₂Cl₄ ? 17NH₃ and [Be(NH₃)₄]Cl₂, is reported. Through NMR spectroscopic and quantum chemical studies, its hydrolysis products in liquid ammonia were identified. These are the dinuclear [Be₂(μ‐OH)(NH₃)₆]³⁺ and the cyclic [Be₂(μ‐OH)₂(NH₃)₄]²⁺ and [Be₃(μ‐OH)₃(NH₃)₆]³⁺ cations. The latter species was isolated as the compound [Be₃(μ‐OH)₃(NH₃)₆]Cl₃ ? 7NH₃. NMR analysis of solutions of BeF₂ in liquid ammonia showed that the [BeF₂(NH₃)₂] molecule was the only dissolved species. It acts as a strong fluoride‐ion acceptor and forms the [BeF₃(NH₃)]^? anion in the compound [N₂H₇][BeF₃(NH₃)]. The compounds presented herein were characterized by single‐crystal X‐ray structure analysis, ⁹Be, ¹⁷O, and ¹⁹F NMR, IR, and Raman spectroscopy, deuteration studies, and quantum chemical calculations. The extension of beryllium chemistry to the ammine system shows similarities but also decisive differences to the aquo system.     

Sparsity reconstruction in electrical impedance tomography: An experimental evaluation

We investigate the potential of sparsity constraints in the electrical impedance tomography (EIT) inverse problem of inferring the distributed conductivity based on boundary potential measurements. In sparsity reconstruction, inhomogeneities of the conductivity are a priori assumed to be sparse with respect to a certain basis. This prior information is incorporated into a Tikhonov-type functional by including a sparsity-promoting ?¹-penalty term. The functional is minimized with an iterative soft shrinkage-type algorithm. In this paper, the feasibility of the sparsity reconstruction approach is evaluated by experimental data from water tank measurements. The reconstructions are computed both with sparsity constraints and with a more conventional smoothness regularization approach. The results verify that the adoption of ?¹-type constraints can enhance the quality of EIT reconstructions: in most of the test cases the reconstructions with sparsity constraints are both qualitatively and quantitatively more feasible than that with the smoothness constraint.     

Lithium ion battery production

Recently, new materials and chemistry for lithium ion batteries have been developed. There is a great emphasis on electrification in the transport sector replacing part of motor powered engines with battery powered applications. There are plans both to increase energy efficiency and to reduce the overall need for consumption of non-renewable liquid fuels. Even more significant applications are dependent on energy storage. Materials needed for battery applications require specially made high quality products.Diminishing amounts of easily minable metal ores increase the consumption of separation and purification energy and chemicals. The metals are likely to be increasingly difficult to process. Iron, manganese, lead, zinc, lithium, aluminium, and nickel are still relatively abundant but many metals like cobalt and rare earths are becoming limited resources more rapidly.The global capacity of industrial-scale production of larger lithium ion battery cells may become a limiting factor in the near future if plans for even partial electrification of vehicles or energy storage visions are realized. The energy capacity needed is huge and one has to be reminded that in terms of cars for example production of 100 MWh equals the need of 3000 full-electric cars. Consequently annual production capacity of 10⁶ cars requires 100 factories each with a 300 MWh capacity. Present day lithium ion batteries have limitations but significant improvements have been achieved recently [1], [2], [3], [4], [5], [6], [7], [8]. The main challenges of lithium ion batteries are related to material deterioration, operating temperatures, energy and power output, and lifetime. Increased lifetime combined with a higher recycling rate of battery materials is essential for a sustainable battery industry.     

Expanding the hydride chemistry: antiperovskites A3MO4H (A = Rb,Cs; M = Mo,W) introducing the transition oxometalate hydrides

The four compounds A₃MO₄H (A = Rb, Cs; M = Mo, W) are introduced as the first members of the new material class of the transition oxometalate hydrides. The compounds are accessible via a thermal synthesis route with carefully controlled conditions. Their crystal structures were solved by neutron diffraction of the deuterated analogues. Rb₃MoO₄D, Cs₃MoO₄D and Cs₃WO₄D crystallize in the antiperovskite-like K₃SO₄F-structure type, while Rb₃WO₄D adopts a different orthorhombic structure. ²H MAS NMR, Raman spectroscopy and elemental analysis prove the abundance of hydride ions next to oxometalate ions and experimental findings are supported by quantum chemical calculations. The tetragonal phases are direct and wide band gap semiconductors arising from hydride states, whereas Rb₃WO₄H shows a unique, peculiar valence band structure dominated by hydride states.

The synthesis, structures and electronic properties of the first four heteroanionic compounds containing both hydride and transition oxometalate ions are reported.     

Stresses in a hollow rotating cylindrically orthotropic tube

Explicit stress distributions for a hollow cylindrically orthotropic tube due to spinning are presented for immediate use in everyday engineering work. The solutions are obtained directly without using the stress function concept. Various boundary condition combinations present in practical applications are considered. Examples are given in order to indicate how the degree of anisotropy influences the stress distributions.Department of Mechanical Engineering, University of Oulu, P.O. Box 444, 90571 Oulu, Finland. Published in Mekhanika Kompozitnykh Materialov, Vol. 32, No. 6, pp 835–841, November–December, 1996.     

An efficient Schottky-varactor frequency multiplier at millimeter waves. Part III. Quadrupler

In this research the efficiency of a millimeter-wave Schottky-varactor quadrupler was studied. Theoretical simulations were carried out by using a nonlinear analysis program to find the optimum embedding impedances for a given diode. Emphasis was placed on the study of optimum idlers at the 2nd and 3rd harmonics, which are essential for a high quadrupling efficiency. For experimental verification a quadrupler for 140–155 GHz output frequency range with fixed idler terminations was constructed. This quadrupler was tested with different output configurations. A 10% tunable bandwidth was obtained with output power in the range of 1.5–2.7 mW whenP _in =40 mW. The highest efficiency measured was 11.3% at 148 GHz with 10 mW input power.     

Neutralization of solvated protons and formation of noble-gas hydride molecules: matrix-isolation indications of tunneling mechanisms?

The (NgHNg)+ cations (Ng = Ar and Kr) produced via the photolysis of HFAr, HFKr, and HBrKr solid mixtures are studied, with emphasis on their decay mechanisms. The present experiments provide a large variety of parameters connected to this decay phenomenon, which allows us to reconsider various models for the decay of the (NgHNg)+ cations in noble-gas matrices. As a result, we propose that this phenomenon could be explained by the neutralization of the solvated protons by electrons. The mechanism of this neutralization reaction probably involves tunneling of an electron from an electronegative fragment or another trap to the (NgHNg)+ cation. The proposed electron-tunneling mechanism should be considered as a possible alternative to the literature models based on tunneling-assisted or radiation-induced diffusion of protons in noble-gas solids. As a novel experimental observation of this work, the efficient formation of HArF molecules occurs at 8 K in a photolyzed HFAr matrix. It is probable that the low-temperature formation of HArF involves local tunneling of the H atom to the Ar-F center, which in turn supports the locality of HF photolysis in solid Ar. In this model, the decay of (ArHAr)+ ions and the formation of HArF molecules observed at low temperatures are generally unconnected processes; however, the decaying (ArHAr)+ ions may contribute to some extent to the formation of HArF molecules.