Quantum algorithms for optimal effective theory of many-body systems

A common situation in quantum many-body physics is that the underlying theories are known but too complicated to solve efficiently. In such cases, one usually builds simpler effective theories as low-energy or large-scale alternatives to the original theories. Here the central tasks are finding the optimal effective theories among a large number of candidates and proving their equivalence to the original theories. Recently quantum computing has shown the potential of solving quantum many-body systems by exploiting its inherent parallelism. It is thus an interesting topic to discuss the emergence of effective theories and design efficient tools for finding them based on the results from quantum computing. As the first step towards this direction, in this paper, we propose two approaches that apply quantum computing to find the optimal effective theory of a quantum many-body system given its full Hamiltonian. The first algorithm searches the space of effective Hamiltonians by quantum phase estimation and amplitude amplification. The second algorithm is based on a variational approach that is promising for near-future applications.Comment: 8 pages, 4 figure

Current evidence, clinical applications, and future directions of transcranial magnetic stimulation as a treatment for ischemic stroke

Transcranial magnetic stimulation (TMS) is a non-invasive brain neurostimulation technique that can be used as one of the adjunctive treatment techniques for neurological recovery after stroke. Animal studies have shown that TMS treatment of rats with middle cerebral artery occlusion (MCAO) model reduced cerebral infarct volume and improved neurological dysfunction in model rats. In addition, clinical case reports have also shown that TMS treatment has positive neuroprotective effects in stroke patients, improving a variety of post-stroke neurological deficits such as motor function, swallowing, cognitive function, speech function, central post-stroke pain, spasticity, and other post-stroke sequelae. However, even though numerous studies have shown a neuroprotective effect of TMS in stroke patients, its possible neuroprotective mechanism is not clear. Therefore, in this review, we describe the potential mechanisms of TMS to improve neurological function in terms of neurogenesis, angiogenesis, anti-inflammation, antioxidant, and anti-apoptosis, and provide insight into the current clinical application of TMS in multiple neurological dysfunctions in stroke. Finally, some of the current challenges faced by TMS are summarized and some suggestions for its future research directions are made

Investigation on the structure and the oxidation activity of the solid carbon produced from catalytic decomposition of methane

The structure and the oxidation activity of the solid carbon produced from catalytic decomposition of methane at different temperatures were investigated using TEM, XRD, Raman and TPO techniques. The results show that the graphitization degree of the solid carbon is increased with decomposition reaction temperature. The addition of ethylene or acetylene to methane can change the growth way of the solid carbon and decrease their graphitization degree. The average oxidation temperature of the solid carbon has a close relationship with the corresponding graphitization degree. The addition of ethylene or acetylene to methane can decrease the average oxidation temperature of the solid carbon. © 2009 Elsevier Ltd. All rights reserved

Quantum algorithms for Schrieffer-Wolff transformation

The Schrieffer-Wolff transformation aims to solve degenerate perturbation problems and give an effective Hamiltonian that describes the low-energy dynamics of the exact Hamiltonian in the low-energy subspace of an unperturbed Hamiltonian. This unitary transformation decoupling the low-energy and high-energy subspaces for the transformed Hamiltonian can be realized by quantum circuits. We give a fully quantum algorithm for realizing the SW transformation. We also propose a hybrid quantum-classical algorithm for finding the effective Hamiltonian on NISQ hardware, where a general cost function is used to indicate the decoupling degree. Numerical simulations without or with noise and experiments on quantum computer ibmq_manila are implemented for a Heisenberg chain model. Our results verify the algorithm and show its validity on near-term quantum computers

Defunctionalization of fructose and sucrose: iron-catalyzed production of 5-hydroxymethylfurfural from fructose and sucrose

A highly efficient iron-catalyzed production of 5-hydroxymethylfurfural (HMF) from sugar is reported. The dehydration of fructose and sucrose has been studied in the presence of different iron salts and co-catalysts. As a result, it was found that fructose and sucrose could be efficiently and selectively converted to HMF using a combination of environmentally friendly FeCl and tetraethyl ammonium bromide (EtNBr) as the catalytic system. For instance, 86% HMF yield at full conversion of fructose was obtained for 2 h at 90 ° C in air. The effects of catalyst concentration, reaction time and reaction temperature were investigated in detail. The electronic absorption spectra of different catalysts were recorded, and the FeClBr ion was considered as the active catalyst species

Solvent-enhanced coupling of sterically hindered reagents and aryl chlorides using functionalized ionic liquids

A highly efficient and poison-resistant system for the Suzuki coupling reaction based on hydroxyl-functionalized ionic liq. solvents has been established. Coupling of RC6H4X (X = Br, I, Cl) and 2-bromothiophene with R1C6H4B(OH)2 in 2-hydroxyethyl-substituted imidazolium ionic liqs. [1-(HOCH2CH2)-3-Me-2-RC3H2N2]A (1-7; C3H4N2 = imidazole; R, A: 1, H, Cl; 2, H, Br; 3, H, BF4; 4, H, PF6; 5, H, Tf2N; 6, Me, Cl; 7, Me, Tf2N), catalyzed by PdCl2 in the presence of Na2CO3 base gave biphenyls RC6H4C6H4R1 (R = 4-NO2, 4-CN, 4-OMe, H, 2-Me, 4-MeCO; R1 = H, 2-Me) and 2-phenylthiophene, resp., with 51-99% yields. Whereas the yields for aryl bromides and iodides are generally high, aryl chlorides gave moderate to good yields. The ionic liq. plays a crit. role in catalyst/substrate activation directly facilitating "ligand-free" coupling reactions

Palladium nanoparticles stabilized by an ionic polymer and ionic liquid: A versatile system for C-C cross-coupling reactions

Highly stable palladium nanoparticles 5 nm diam., protected by an imidazolium-based ionic polymer in a nitrile-functionalized ionic liq., have been prepd. and characterized by TEM. These Pd nanoparticles are excellent precatalysts for Suzuki, Heck, and Stille coupling reactions and can be stored without undergoing degrdn. for at ³2 yr. The nanoparticle system may therefore be considered as an alternative to the traditional palladium on carbon precatalyst used in many C-C coupling reactions, and also allowing reactions to be conducted under solvent-free conditions

Enzymatic hydrolysis lignin dissolution and low-temperature solvolysis in ethylene glycol

| openaire: EC/H2020/101006744/EU//EHLCATHOL Funding Information: This work has received funding from the European Union’s Horizon 2020 research and innovation program , (BUILDING A LOW-CARBON, CLIMATE RESILIENT FUTURE: SECURE, CLEAN AND EFFICIENT EN-ERGY) under Grant Agreement No 101006744. The content presented in this document represents the views of the authors, and the European Commission has no liability in respect of the content. Y.S. Sang and G. Li would like to express their gratitude to both the China Scholarship Council ( 202006250156 , 202208320030 ) and the EU-101006744 project. Publisher Copyright: © 2023 The Author(s)The dissolution and solvolysis processes of enzymatic hydrolysis lignin (EHL) in ethylene glycol are investigated. Ethylene glycol exhibits high EHL solubility and achieves complete EHL dissolution at room temperature. Gaussian simulation reveals that van de Waals interactions between ethylene glycol and EHL, including C-H⋯O and lone pair⋯π interactions, break the π-π stacking in EHL, achieving complete EHL dissolution. EHL is partly depolymerized in ethylene glycol at 200 °C even without a catalyst due to the strong van de Waals interactions. When NaOH and Ni are used as co-catalysts, EHL is efficiently depolymerized at 200 °C, and the overall monomer yield reaches 18.8 wt%. Fourier transform infrared spectroscopy (FT-IR) and molecular dynamics simulation results indicate that the adsorption of ethylene glycol over Ni surface hinders the adsorption of lignin fragments and monomers. Hence, EHL catalytic solvolysis in ethylene glycol occurs in the liquid phase, where OH− of NaOH promotes the EHL linkage breakage and active hydrogen atoms formed on Ni surface stabilize the active monomers.Peer reviewe

Suzuki Coupling Reactions in Ether-Functionalized Ionic Liquids: The Importance of Weakly Interacting Cations

Imidazolium- and pyridinium-based ionic liqs. with ether/polyether substituents have been evaluated as solvents for palladium-catalyzed Suzuki C-C coupling reactions. In general, reactions proceed more efficiently in these solvents compared to other ionic liqs., which is believed to be due to better stabilization of the palladium catalyst, involving weak interactions with the ether groups. The position and the no. of oxygen atoms in the ether side chain strongly influence the outcome of the coupling reactions in the imidazolium-based ionic liqs., whereas for the pyridinium-based liqs. no influence is obsd. Carbene derivs., generated from the imidazolium-based ionic liqs., are believed to play a role by terminating the catalytic cycle, and representative species have been isolated and characterized from stoichiometric reactions