The Sparse-Grid-Based Adaptive Spectral Koopman Method

The adaptive spectral Koopman (ASK) method was introduced to numerically solve autonomous dynamical systems that lay the foundation of numerous applications across different fields in science and engineering. Although ASK achieves high accuracy, it is computationally more expensive for multi-dimensional systems compared with conventional time integration schemes like Runge-Kutta. In this work, we combine the sparse grid and ASK to accelerate the computation for multi-dimensional systems. This sparse-grid-based ASK (SASK) method uses the Smolyak structure to construct multi-dimensional collocation points as well as associated polynomials that are used to approximate eigenfunctions of the Koopman operator of the system. In this way, the number of collocation points is reduced compared with using the tensor product rule. We demonstrate that SASK can be used to solve partial differential equations based-on their semi-discrete forms. Numerical experiments illustrate that SASK balances the accuracy with the computational cost, and hence accelerates ASK.Comment: 21 pages, 5 figure

Tetra­ethyl­ammonium dicyanidobis(ethane-1,2-dithiol­ato)tetra-μ3-sulfido-dimolybdenum(V)dicopper(I)

The title compound, (C8H20N)2[Cu2Mo2(C2H4S2)2(CN)2S4], is a sulfide-bridged tetranuclear complex in which the complex anion comprises one [(edt)2Mo2S2(μ-S)2]2− unit (edt = ethanedithiol­ate) and two CuCN units joined through six Cu—μ3-S bonds, thus forming a cubane-like [Mo2S4Cu2] core. There are two independent cation–anion complex entities in the asymmetric unit. Bond distances are normal for this type of complex [ranges: Mo—S = 2.193 (2)–2.390 (2); Cu—S = 2.266 (2)–2.470 (2); Cu—C = 1.899 (7)–1.911 (9) Å]. One of the thiol­ato C atoms is disordered over two sites in a 0.52 (3):0.48 (3) ratio

A TOU Pricing Mechanism to Promote Renewable Energy Consumption: The Case of the Western Inner Mongolia Grid in China

The curtailment of wind power and photovoltaic power is becoming increasingly serious from the year 2012 to present in China. And the small installed capacity captive coal-fired power plants have been developed rapidly aiming to cut production costs. Therefore, by the substitution of renewable energy for captive coal-fired power plants, this paper establishes a time-of-use (TOU) pricing mechanism with a linkage between the supply side and the demand side to promote renewable energy consumption, which is applied to the Western Inner Mongolia grid in China. The results show that the benefits to the grid company, electricity users, renewable energy producers, and social environment are influenced by the quantity of renewable energy purchased in the market, the market price for renewable energy, the quantity of electricity from grid to peak shaving, the carbon price, and the quantity of electricity generated by captive coal-fired power plants shifting to grid, in which the first factor has the greatest influence on the benefits of stakeholders. Furthermore, improving the accuracy of renewable energy generation forecast and optimizing using electricity behaviors by considering the renewable energy generation characteristics could ensure the TOU mechanism implementation successfully

Optimizing the Age of Information in RIS-aided SWIPT Networks

In this letter, a reconfigurable intelligent surface (RIS)-assisted simultaneous wireless information and power transfer (SWIPT) network is investigated. To quantify the freshness of the data packets at the information receiver, the age of information (AoI) is considered. To minimize the sum AoI of the information users while ensuring that the power transferred to energy harvesting users is greater than the demanded value, we formulate a scheduling scheme, and a joint transmit beamforming and phase shift optimization at the base station (BS) and RIS, respectively. The alternating optimization (AO) algorithm is proposed to handle the coupling between active beamforming and passive RIS phase shifts, and the successive convex approximation (SCA) algorithm is utilized to tackle the non-convexity of the formulated problems. The improvement in terms of AoI provided by the proposed algorithm and the trade-off between the age of information and energy harvesting is quantified by the numerical simulation results

Inhibitory Effect of Phthalic Acid on Tyrosinase: The Mixed-Type Inhibition and Docking Simulations

Tyrosinase inhibition studies are needed due to the medicinal applications such as hyperpigmentation. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics was important. We predicted the 3D structure of tyrosinase, used a docking algorithm to simulate binding between tyrosinase and phthalic acid (PA), and studied the reversible inhibition of tyrosinase by PA. PA inhibited tyrosinase in a mixed-type manner with a Ki = 65.84 ± 1.10 mM. Measurements of intrinsic and ANS-binding fluorescences showed that PA induced changes in the active site structure via indirect binding. Simulation was successful (binding energies for Dock6.3 = −27.22 and AutoDock4.2 = −0.97 kcal/mol), suggesting that PA interacts with LEU73 residue that is predicted commonly by both programs. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors

Energy-Efficient Cell-Free Network Assisted by Hybrid RISs

In this letter, we investigate a cell-free network aided by hybrid reconfigurable intelligent surfaces (RISs), which consists of a mixture of passive and active elements that are capable of amplifying and reflecting the incident signal. To maximize the energy efficiency (EE) of the system, we formulate a joint transmit beamforming and RIS coefficients optimization problem. To deal with the fractional objective function, Dinkelbach transform, Lagrangian dual reformulation, and quadratic transform are utilized, with a block coordinate descent (BCD) based algorithm proposed to decouple the variables. In addition, successive convex approximation (SCA) method is applied to iteratively to tackle the non-convexity of the sub-problems. Simulation results illustrate the effectiveness and convergence of the proposed algorithm through analyzing the EE and sum rate performance with varying parameter settings. The proposed hybrid RISs schemes can achieve 92% of the sum rate but 188% of EE of active RISs schemes. As compared with passive RISs, 11% gain in sum rate can be achieved with comparable EE

Molecular cloning and expression of a novel trehalose synthase gene from Enterobacter hormaechei

<p>Abstract</p> <p>Background</p> <p>Trehalose synthase (TreS) which converts maltose to trehalose is considered to be a potential biocatalyst for trehalose production. This enzymatic process has the advantage of simple reaction and employs an inexpensive substrate. Therefore, new TreS producing bacteria with suitable enzyme properties are expected to be isolated from extreme environment.</p> <p>Results</p> <p>Six TreS producing strains were isolated from a specimen obtained from soil of the Tibetan Plateau using degenerate PCR. A novel <it>treS </it>gene from <it>Enterobacter hormaechei </it>was amplified using thermal asymmetric interlaced PCR. The gene contained a 1626 bp open reading frame encoding 541 amino acids. The gene was expressed in <it>Escherichia coli</it>, and the recombinant TreS was purified and characterized. The purified TreS had a molecular mass of 65 kDa and an activity of 18.5 U/mg. The optimum temperature and pH for the converting reaction were 37°C and 6, respectively. Hg²⁺, Zn²⁺, Cu²⁺and SDS inhibited the enzyme activity at different levels whereas Mn²⁺showed an enhancing effect by 10%.</p> <p>Conclusion</p> <p>In this study, several TreS producing strains were screened from a source of soil bacteria. The characterization of the recombinant TreS of <it>Enterobacter hormaechei </it>suggested its potential application. Consequently, a strategy for isolation of TreS producing strains and cloning of novel <it>treS </it>genes from natural sources was demonstrated.</p