High order finite volume methods on wavelet-adapted grids with local time-stepping on multicore architectures for the simulation of shock-bubble interactions

We present a space–time adaptive solver for single- and multi-phase compressible flows that couples average interpolating wavelets with high-order finite volume schemes. The solver introduces the concept of wavelet blocks, handles large jumps in resolution and employs local time-stepping for efficient time integration. We demonstrate that the inherently sequential wavelet-based adaptivity can be implemented efficiently in multicore computer architectures using task-based parallelism and introducing the concept of wavelet blocks. We validate our computational method on a number of benchmark problems and we present simulations of shock-bubble interaction at different Mach numbers, demonstrating the accuracy and computational performance of the method.     

Coordination‐Driven Hierarchical Assembly of Silver Nanoparticles on MoS2 Nanosheets for Improved Lithium Storage

We report a novel strategy for the hierarchical assembly of Ag nanoparticles (NPs) on MoS₂ nanosheets through coordination by using a multifunctional organic ligand. The presence of Ag NPs on the surface of MoS₂ nanosheets inhibits their agglomeration, thereby providing increased interlayer spacing for easy Li⁺ ion intercalation. Such a unique hybrid architecture also ensures sufficient percolation pathways on the whole surface of the MoS₂ nanosheets. Moreover, the high rigidity and low deformability of the Ag NPs effectively preserve the hybrid architecture during the charge–discharge process, which translates into a high cycle stability. A prominent synergistic effect between MoS₂ and Ag is witnessed. When the Ag content is only 5 wt %, the Ag–MoS₂ hybrid delivers a reversible capacity as high as 920 mA h g^?1 at a current density of 100 mA g^?1, making the Ag–MoS₂ hybrid an attractive candidate for next‐generation LIBs.     

The heterometallic cadmium–silver complex cis‐bis[dicyanidoargentato(I)‐κN]bis(5,5′‐dimethyl‐2,2′‐bipyridyl‐κ2N,N′)cadmium(II) monohydrate

In the title complex, [Ag₂Cd(CN)₄(C₁₂H₁₂N₂)₂]·H₂O or cis‐[Cd{Ag(CN)₂}₂(5,5′‐dmbpy)₂]·H₂O, where 5,5′‐dmbpy is 5,5′‐dimethyl‐2,2′‐bipyridyl, the asymmetric unit consists of a discrete neutral [Cd{Ag(CN)₂}₂(5,5′‐dmbpy)₂] unit and a solvent water molecule. The Cd^II cation is coordinated by two bidentate chelate 5,5′‐dmbpy ligands and two monodentate [Ag^I(CN)₂]⁻ anions, which are in a cis arrangement around the Cd^II cation, leading to an octahedral CdN₆ geometry. The overall structure is stabilized by a combination of intermolecular hydrogen bonding, and Ag^I...Ag^I and π–π interactions, forming a three‐dimensional supramolecular network.     

Pillararene‐Based Assemblies: Design Principle,Preparation and Applications

In this review, we highlight recent advancements on pillararene‐based assemblies. The driving forces for the formation of the pillararene‐based assemblies are discussed first. The host–guest interactions are deemed as not only general strategy for constructing assemblies but also essential components for preventing the assemblies from the dissociation. Solvent effect is also important in the assembling process, since it could influence the host–guest interactions and provide solvophobic effect on pillararenes for the assembly. Then, several pillararene‐based assembly architectures are introduced, including pillararene‐based interlocked structures, such as (poly)pseudorotaxanes, (poly)rotaxanes, and daisy chains, classified by their topological structures and synthetic strategy. The morphologies of the supramolecular assemblies are divided into several types, for example, nanospheres, nanotubes and supramolecular polymers. Furthermore, the functions and potential applications are summarized accompanied with related assembly structures. The review not only provides fundamental findings, but also foresights future research directions in the research area of pillararene‐based assemblies.     

Noncovalent synthesis of supramolecular dendritic architectures in water

Water‐soluble guest–host complexes are prepared in a two‐step process. For this a new, polydisperse ethylene glycol containing guest molecule is synthesized that is soluble in both chloroform and water. This guest is able to bind to urea–adamantyl‐modified poly(propylene imine) dendrimers in chloroform in a noncovalent manner. When the chloroform is slowly evaporated and D₂O is added, the hydrophobic dendrimer is solubilized in water. This is not possible when the hydrophobic dendrimer is directly added to the hydrophilic guests in water. When the unmodified poly(ethylene glycol) starting material is used, no solubilization occurs, and this indicates that the urea–acetic acid head group is necessary to solubilize the dendrimer. Approximately 26 guests are required for solubilization of the dendrimer. A lower number of guests results in aggregation and precipitation of the dendrimer. A monodisperse guest molecule has been used in NMR studies to show that the guest molecule binds with its acidic head group to the periphery of the dendrimer. This methodology opens the way to functional dendrimer aggregates in aqueous media. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6431–6437, 2005     

A perspective on artificial intelligence: Learning to learn

The classical approach to the acquisition of knowledge in artificial intelligence has been to program the intelligence into the machine in the form of specific rules for the application of the knowledge: expert systems. Unfortunately, the amount of time and resources required to program an expert system with sufficient knowledge for non-trivial problem-solving is prohibitively large. An alternative approach is to allow the machine tolearn the rules based upon trial-and-error interaction with the environment, much as humans do. This will require endowing the machine with a sophisticated set of sensors for the perception of the external world, the ability to generate trial actions based upon this perceived information, and a dynamic evaluation policy to allow it to measure the effectiveness of its trial actions and modify its repertoire accordingly. The principles underlying this paradigm, known ascollective learning systems theory, have already been applied to sophisticated gaming problems, demonstrating robust learning and dynamic adaptivity.The fundamental building block of a collective learning system is thelearning cell, which may be embedded in a massively parallel, hierarchical data communications network. Such a network comprising 100 million learning cells will approach the intelligence capacity of the human cortex. In the not-too-distant future, it may be possible to build a race of robotic slaves to perform a wide variety of tasks in our culture. This goal, while irresistibly attractive, is most certainly fraught with severe social, political, moral, and economic difficulties.This paper was given as an invited talk on the 12th Symposium on Operations Research, University of Passau, September 1987.     

Conjugated asymmetric donor-substituted 1,3,5-triazines: new host materials for blue phosphorescent organic light-emitting diodes

Conjugated asymmetric donor-substituted 1,3,5-triazines (ADTs) have been synthesized by nucleophilic substitution of organolithium catalyzed by [Pd(PPh(3))(4)]. Theoretical and experimental investigations show that ADTs possess high solubility and thermostability, high fluorescent quantum yield (35%), low HOMO (-6.0 eV) and LUMO (-2.8 eV), and high triplet energy (E(T), 3.0 eV) according to the different substitution pattern of triazine. The application as host materials for blue PHOLEDs yielded a maximum current efficiency of 20.9 cd A(-1), a maximum external quantum efficiency of 9.8%, and a brightness of 9671 cd m(-2) at 5.4 V, making ADTs good candidates for optoelectronic devices.     

Scalable synthesis of an architectural library of well‐defined poly(acrylic acid) derivatives: Role of structure on dispersant performance

The synthesis and systematic comparison of a comprehensive library of well‐defined polymer architectures based on poly(acrylic acid) is reported. Through the development of new synthetic methodologies, linear, single branched, precision‐branched comb, and star polymers were prepared and their performance as dispersants was evaluated. The ability to accurately control chain lengths and branch points allows the subtle interplay between structure and dispersant performance to be defined and affords critical insights into the design of improved polymeric additives for coating formulations. The general industrial relevance of ionic polymers and branched macromolecular architectures supports these design rules for a wide range of other applications and materials, including as additives for personal care products and in water treatment. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 716–725     

Modular Synthesis of Linear Bis‐ and Tris‐monodentate Fused [6]Polynorbornane‐Based Ligands and their Assembly into Coordination Cages

A modular approach has been developed for the synthesis of rigid linear di‐ and tritopic ligands based on a fused [6]polynorbornane scaffold. The design provides up to three sites for installing functionality, including both “ends” and a “central” position with the advantage that each region can be independently addressed during synthesis. To illustrate the utility of the approach, both pyridyl and picolyl units were incorporated to provide six new ligands, with centers and ends either matched or mismatched. Indeed, both [M₂L₄] cages with endohedral functionality and [M₃L₄] complexes were cleanly produced from these ligands with assembled structures confirmed by using ¹H NMR spectroscopy, HRMS, and molecular modelling.     

Metal-organic coordination architectures of azole heterocycle ligands bearing acetic acid groups: Synthesis, structure and magnetic properties

Four new coordination complexes with azole heterocycle ligands bearing acetic acid groups, [Co(L¹)₂]_n (1), [CuL¹N₃]_n (2), [Cu(L²)₂·0.5C₂H₅OH·H₂O]_n (3) and [Co(L²)₂]_n (4) (here, HL¹=1H-imidazole-1-yl-acetic acid, HL²=1H-benzimidazole-1-yl-acetic acid) have been synthesized and structurally characterized. Single-crystal structure analysis shows that 3 and 4 are 2D complexes with 4⁴-sql topologies, while another 2D complex 1 has a (4³)₂(4⁶)-kgd topology. And 2 is a 3D complex composed dinuclear μ_1,1-bridging azido Cu^II entities with distorted rutile topology. The magnetic properties of 1 and 2 have been studied.