A New Taraxastane-type Triterpenoid from Potentilla multicaulis

The genus Potentilla (Rosaceae) consists of about 200 species distributed in many countries, among them about 90 species grow in China1. Some species of Potentilla plants have long been used as traditional Chinese medicinal herbs for anti-rheumatism, deto…     

Screening the anti-gout traditional herbs from TCM using an in vitro method

The aim of this work was to evaluate the ability of 33 herbal extracts in inhibiting the acute inflammation and xanthine oxidase(XOD) activity.The anti-inflammation effects of the herbal extracts were detected by an in vitro cell model,which was established by stimulating human umbilical vein endothelial cells(HUVEC) using sodium urate(MSU).In this model,the intercellular adhesion molecule-1(ICAM-1) and interleukin-1 beta(IL-1β) were expressed,and the anti-inflammation effects of herbal extracts were evaluated by detecting the content changes of ICAM-1 and IL-1β in cell lysates and cell culture supernates using an enzyme-linked immunosorbent assay(ELISA).Moreover,an ultrahigh performance liquid chromatography and tandem mass spectrometry(UPLC-MS/MS) method was used for the detection of XOD activity and the screening of XOD inhibitors in this research.The amount of uric acid from each analyte was directly detected using the multiple reaction monitoring mode and the uric acid level could be reduced via the addition of an inhibitor.Results indicated that Salviae Miltiorrhizae Radix et Rhizome,Rhei Radix et Rhizoma,Polygoni Cuspidati Rhizoma et Radix,Selaginellae Herba,Paeoniae Radix Rubra,especially Ginkgo Folium seemed to be more effective in anti-inflammation and inhibiting XOD activity.The anti-inflammation and enzyme inhibitory activities of the herbal extracts may be correlated with their bioactive components.And the differences between the herbal extracts were correlated with the amount of flavonoid and anthraquinone components.In our study,we have investigated the potential anti-inflammation bioactivity of 33 herbal extracts in vitro,which could provide a reference for further in vivo research in the prevention and treatment of gout.     

Highly chemoselective lipase from Candida sp. 99-125 catalyzed ring-opening polymerization for direct synthesis of thiol-terminated poly(ε-caprolactone)

Lipase from Candida sp. 99-125 catalyzed ring-opening polymerization of ε-caprolactone in the presence of 6-mercapto-1-hexanol was presented as a new metal-free approach for direct synthesis of welldefined thiol-terminated poly(ε-caprolactone). Remarkably, high chemoselectivity of lipase from Candida sp. 99-125 toward hydroxyl and thiol was exhibited and quantitative thiol fidelity over 90% was achieved. The tedious protecting/deprotecting steps for thiol and metal residue were avoided. The polymerizations with around 70% monomer conversion were conducted in bulk and toluene at relative low temperature of 40 ℃. Number-average molecular weight of resulted polymers ranged from 3000 to 4700 Da by changing the feed ratio between monomer and initiator. The structures of obtained thiolterminated poly(ε-caprolactone) were demonstrated by combining NMR and SEC analyses.     

Biopolymer passivation for high-performance perovskite solar cells by blade coating

Thin films of perovskite deposited from solution inevitably introduce large number of defects,which serve as recombination centers and are detrimental for solar cell performance.Although many small molecules and polymers have been delicately designed to migrate defects of perovskite films,exploiting credible passivation agents based on natural materials would offer an alternative approach.Here,an ecofriendly and cost-effective biomaterial,ploy-L-lysine(PLL),is identified to effectively passivate the defects of perovskite films prepared by blade-coating.It is found that incorporation of a small amount(2.5 mg mL^-1)of PLL significantly boosts the performance of printed devices,yielding a high efficiency of 19.45% with an increase in open-circuit voltage by up to 100 mV.Density functional theory calculations combined with X-ray photoelectron spectroscopy reveal that the functional groups(-NH2,-COOH)of PLL effectively migrate the Pb-I antisite defects via Pb-N coordination and suppress the formation of metallic Pb in the blade-coated perovskite film.This work suggests a viable avenue to exploit passivation agents from natural materials for preparation of high-quality perovskite layers for optoelectronic applications.     

Ultrafine Fe/Fe3C decorated on Fe-Nx-C as bifunctional oxygen electrocatalysts for efficient Zn-air batteries

Efficient bifunctional oxygen electrocatalysts for ORR and OER are fundamental to the development of high performance metal-air batteries.Herein,a facile cost-efficient two-step pyrolysis strategy for the fabrication of a bifunctional oxygen electrocatalyst has been proposed.The efficient non-preciousmetal-based electrocatalyst,Fe/Fe₃C@Fe-N_x-C consists of highly curved onion-like carbon shells that encapsulate Fe/Fe₃C nanoparticles,distributed on an extensively porous graphitic carbon aerogel.The obtained Fe/Fe₃C@Fe-N_x-C aerogel exhibited superb electrochemical activity,excellent durability,and high methanol tolerance.The experimental results indicated that the assembly of onion-like carbon shells with encapsulated Fe/Fe₃C yielded highly curved carbon surfaces with abundant Fe-Nxactive sites,a porous structure,and enhanced electrocatalytic activity towards ORR and OER,hence displaying promising potential for application as an air cathode in rechargeable Zn-air batteries.The constructed Zn-air battery possessed an exceptional peak power density of~147 mW cm^-2,outstanding cycling stability(200 cycles,1 h per cycle),and a small voltage gap of 0.87 V.This study offers valuable insights regarding the construction of low-cost and highly active bifunctional oxygen electrocatalysts for efficient air batteries.     

Exploring the mechanism of Ta3N5/KTaO3 photocatalyst for overall water splitting by first-principles calculations

The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta₃N₅ single crystals grown on the surface of KTaO₃ can accomplish photocatalytic overall water splitting for the first time.In order to comprehend the underlying mechanism of this photocatalytic system,we have performed a systematic study based on density functional theory first-principles calculations.Ta₃N₅(010)/KTaO₃(110)slab models have been built according to experimental observations by considering two common terminations of KTaO₃(110)surface,named as Ta₃N₅/O₂ and Ta₃N₅/KTaO.The formations of interfacial bonds are thermodynamically stable,showing a covalent interaction between two components of a heterostructure.Ta₃N₅/O₂ has a higher mobility of photogenerated charge carriers and lower recombination rate of charge carriers than Ta₃N₅/KTaO.The light absorption of heterostructures displays the feature of KTaO₃ in the short wavelength region and the characteristic of Ta₃N₅ in the long wavelength region.The calculated band offsets show that Ta₃N₅/O₂ and Ta₃N₅/KTaO have distinct Type-II band alignments,with Ta₃N₅ as the accumulator of photoinduced electrons in the former and the collector of photogenerated holes in the latter,respectively.The difference in charge density and electrostatic potential between two components acts as a driving force to promote the transfer of electrons and holes to different domains of the interface,which is beneficial to extend the lifetime of photoinduced carriers.Our results demonstrate that the function of Ta₃N₅ in Ta₃N₅/KTaO₃ photocatalytic system is determined by the termination property of KTaO₃(110)surface,which provides a likely reason of the observed photocatalytic activity of overall water splitting achieved by Ta₃N₅ synthesized by using KTaO₃ as a precursor for the nitridation reaction.     

A composite micromotor driven by self-thermophoresis and Brownian rectification

Brownian motors and self-phoretic microswimmers are two typical micromotors, for which thermal fluctuations play different roles. Brownian motors utilize thermal noise to acquire unidirectional motion, while thermal fluctuations randomize the self-propulsion of self-phoretic microswimmers. Here we perform mesoscale simulations to study a composite micromotor composed of a self-thermophoretic Janus particle under a time-modulated external ratchet potential. The composite motor exhibits a unidirectional transport, whose direction can be reversed by tuning the modulation frequency of the external potential. The maximum transport capability is close to the superposition of the drift speed of the pure Brownian motor and the self-propelling speed of the pure self-thermophoretic particle. Moreover, the hydrodynamic effect influences the orientation of the Janus particle in the ratched potential, hence also the performance of the composite motor. Our work thus provides an enlightening attempt to actively exploit inevitable thermal fluctuations in the implementation of the self-phoretic microswimmers.     

Recent progress on DNA block copolymer

Organic polymers are combined with DNA resulting DNA block copolymers (DBCs) that can simultaneously show the properties of the polymer and DNA. We will discuss some examples of recent developments in the syntheses, structure manipulations, and applications of DBCs.     

A system consisted of flame ionization detector and sulfur chemiluminescence detector for interference free determination of total sulfur in natural gas

A new detection system consisted of a flame ionization detector (FID) and a sulfur chemiluminescence detector (SCD) was developed for sensitive and interference free determination of total sulfur in natural gas by non-separation gas chromatography. In this system, sulfur containing compounds and hydrocarbons were firstly burned in the FID using oxygen rich flame and converted to SO₂, CO₂ and H₂O, respectively. The products from FID were transported into the SCD with hydrogen rich atmosphere wherein only SO₂ could be reduced to SO and reacted with O₃ to produce characteristic chemiluminescence. Therefore, the chemiluminescence of CO found in conventional SCD were eliminated because CO₂ could not be reduced to CO under these conditions. The experimental parameters were systematically investigated. Limit of detection obtained by the proposed system is better than 0.5 μmol/mol for total sulfur and superior to those previously reported. The proposed method not only retains the advantages of the conventional SCD but also provides several unique advantages including no hydrocarbon interference, better stability, and easier calculation. The utility of this technique was demonstrated by the determination of total sulfur in real samples and two certified reference materials (GBW 06332 and GBW (E) 061320).     

Noisy intermediate-scale quantum computers

Quantum computers have made extraordinary progress over the past decade, and significant milestones have been achieved along the path of pursuing universal fault-tolerant quantum computers. Quantum advantage, the tipping point heralding the quantum era, has been accomplished along with several waves of breakthroughs. Quantum hardware has become more integrated and architectural compared to its toddler days. The controlling precision of various physical systems is pushed beyond the fault-tolerant threshold. Meanwhile, quantum computation research has established a new norm by embracing industrialization and commercialization. The joint power of governments, private investors, and tech companies has significantly shaped a new vibrant environment that accelerates the development of this field, now at the beginning of the noisy intermediate-scale quantum era. Here, we first discuss the progress achieved in the field of quantum computation by reviewing the most important algorithms and advances in the most promising technical routes, and then summarizing the next-stage challenges. Furthermore, we illustrate our confidence that solid foundations have been built for the fault-tolerant quantum computer and our optimism that the emergence of quantum killer applications essential for human society shall happen in the future.