The human ether-à-go-go-related potassium channel (hERG, Kv11.1) is a voltage-dependent channel known for its role in repolarizing the cardiac action potential. hERG alteration by mutation or ...pharmacological inhibition produces Long QT syndrome and the lethal cardiac arrhythmia torsade de pointes. We have determined the molecular structure of hERG to 3.8 Å using cryo-electron microscopy. In this structure, the voltage sensors adopt a depolarized conformation, and the pore is open. The central cavity has an atypically small central volume surrounded by four deep hydrophobic pockets, which may explain hERG’s unusual sensitivity to many drugs. A subtle structural feature of the hERG selectivity filter might correlate with its fast inactivation rate, which is key to hERG’s role in cardiac action potential repolarization.
Display omitted
•hERG channel structure is determined at 3.8 Å using single-particle cryo-EM•hERG channel is open with the voltage sensors in a depolarized conformation•Unique properties of the central cavity likely contribute to hERG block by many drugs•A subtle rearrangement in hERG’s selectivity filter correlates with rapid inactivation
Structural analysis of the hERG channel helps to understand known human channelopathy mutations and why the channel is extremely sensitive to a wide range of drugs.
The technical supply potential of biomass and the associated greenhouse gas (GHG) emissions are widely studied in the literature. However, relatively few studies have examined the role of biomass ...co-firing for future electricity in China by integratedly considering the economic supply potential and GHG effects. To fill this gap, we choose the Jiangsu Province in China as a case study and build up a partial equilibrium model with multiple agricultural commodities. Using this model combined with a life cycle assessment, we jointly determine the economic potential of the biomass supply for a biomass co-firing purpose and social benefits, including the agricultural producers’ surplus and GHG mitigation potential. The simulation incorporates the county-level biomass market of various crop residues as well as endogenous crop prices and transportation costs. We find that 0.7–12.5 M MT of residue-based biomass are economically viable for co-firing in coal-based power plants (up to 20%) at biomass prices between USD 50 and USD 100/MT. The net GHG savings achieved at these biomass prices are from 3.2 to 59 M MTCO2e. Our findings indicate that biomass co-firing with coal in power plants would be a feasible low-carbon energy transition pathway if the biomass price is above USD 50/MT. In addition to biomass prices, other factors such as crop yields, production costs of residues, and transportation costs are found to be impactful on the economic viability of biomass and GHG savings. Our results can inform policy to develop localized carbon reduction strategies in provinces with abundant biomass resources and a high share of coal-fired electricity.
Agricultural land and forestland are considered as two largest potential biomass sources for meeting the Renewable Fuel Standard (RFS) mandate for cellulosic biofuels. However, the land use change ...and greenhouse gas (GHG) savings with both agricultural and forest biomass production are yet to be examined systematically. This paper examines the effects of implementing a 16-billion gallon (60 billion liters) cellulosic biofuel mandate by 2035 on the mix of agricultural and forest biomass, land use change and GHG emissions by using a dynamic partial equilibrium model of the agricultural, forestry and transportation sectors in the US. Our results show that crop residues play a significant role in supplying cellulosic ethanol before 2030, while energy crops are the major feedstocks used for meeting the RFS cellulosic mandate after 2030. Milling and logging residues are economically viable supplements to agricultural biomass for cellulosic ethanol production, though their role in total biomass is small. Across different scenarios of cellulosic ethanol mandate that can be met with either agricultural biomass only or with both agricultural and forest biomass, we find GHG savings from displacing the gasoline range from 0.61 to 0.82 B MgCO2e over the 2015–2035 period. Induced land use change effects associated with expanded feedstock production are modest between and within the agricultural and forestry sectors. We conclude that a mixed feedstock base maximizes the economic and environmental benefits of cellulosic biofuel production. The mitigation potential of cellulosic biofuels is severalfold larger than natural-based solutions such as grassland restoration.
Panax notoginseng (Burk.) F. H. Chen, also called Sanqi, is a widely used traditional Chinese medicine, which has long history used as herbal medicines. It is currently an important medicinal ...material in China, holding the first place in the sale volume of the whole patent medicines market in China, and the market size of the single species has exceeded 10 billion yuan. In addition, P. notoginseng is an important constituent part of many famous Chinese patent medicines, such as Compound Danshen Dripping Pills and Yunnan Baiyao.
P. notoginseng saponins (PNSs), which are the major active components of P. notoginseng, are a kind of chemical mixture containing different dammarane-type saponins. Many studies show that PNSs have been extensively used in medical research or applications, such as atherosclerosis, diabetes, acute lung injury, cancer, and cardiovascular diseases. In addition, various PNS preparations, such as injections and capsules, have been made commercially available and are widely applied in clinical practice.
Since the safety and efficacy of compounds are related to their qualitative and quantitative analyses, this review briefly summarizes the analytic approaches for PNSs and their biological effects developed in the last decade.
This review conducted a systematic search in electronic databases, such as Pubmed, Google Scholar, SciFinder, ISI Web of Science, and CNKI, since 2009. The information provided in this review is based on peer-reviewed papers and patents in either English or Chinese.
At present, the chromatographic technique remains the most extensively used approach for the identification or quantitation of PNSs, coupled with different detectors, among which the difference mainly lies in their sensitivity and specificity for analyzing various compounds. It is well-known that PNSs have traditionally strong activity on cardiovascular diseases, such as atherosclerosis, intracerebral hemorrhage, or brain injury. The recent studies showed that PNSs also responded to osteoporosis, cancers, diabetes, and drug toxicity. However, some other studies also showed that some PNSs injections and special PNS components might lead to some biological toxicity under certain dosages.
This review may be used as a basis for further research in the field of quantitative and qualitative analyses, and is expected to provide updated and valuable insights into the potential medicinal applications of PNSs.
Intelligent education is an inevitable trend in the development of teaching in colleges and universities, and this paper constructs a smart teaching mode of business English in colleges and ...universities based on the achievement scalar function and multi-objective optimization algorithm. In the paper, the mixed difference operator is used to improve the singularity of business English teaching objectives and to diversify the teaching objectives. The achievement scalar function is used to assess students’ business English proficiency, and teaching strategies are proposed based on the target distribution parameters. By exploring the intrinsic connection between diversified objectives and intelligent classrooms, the intelligent classroom teaching model is constructed. Analyzing the learning effect and language proficiency of students under the smart classroom teaching mode of business English, the feasibility and effectiveness of the teaching mode are demonstrated. The results show that in terms of creating a relaxed classroom learning environment, 0.7267 students agreed that the smart classroom could create a relaxing and enjoyable learning environment, and around 0.7 learners believed that the learning resources released by teachers through the smart classroom could further promote their understanding of knowledge. This study provides an effective reference guide for business English teaching, which is more conducive to the development and progress of business English education.
Copper-based catalysts for CO2 hydrogenation to methanol are supported on ZrO2 and CeO2, respectively. Reaction results at 3.0 MPa and temperatures between 200 and 300 °C reveal that Cu catalysts ...supported on ZrO2 and CeO2 exhibit better activity and selectivity than pure Cu catalyst due to Cu-support (ZrO2 and CeO2) interaction. Combining the structural characterizations with in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS), Cu/CeO2 shows the higher methanol selectivity due to the formation of main carbonates intermediates, which are closely related with the oxygen vacancies over Cu/CeO2. In contrast, bicarbonate and carboxyl species are observed on Cu/ZrO2, which originates from the hydroxyl groups presented on catalyst surfaces. Difference in CO2 adsorption intermediates results in the distinct methanol selectivity over the two catalysts.
The difference in metal-support interaction over Cu/CeO2 and Cu/ZrO2 leads to different reaction pathways. The former abides by HCOO route while the latter follows COOH route, and then produces different methanol selectivities. Display omitted
Metallurgical processes for scandium recovery from various resources are reviewed. Scandium is mainly recovered as by-product from residues, tailings and waste liquors in the production of other ...metals such as rare earths, uranium, titanium, tungsten, aluminium, nickel, tantalum and niobium. Bauxite and nickel laterite ores are proposed as the most promising scandium resources for its production. Currently, the methods combined with hydro- and pyro-metallurgical processes, including ore pre-treatment, leaching, solvent extraction, precipitation and calcination, are commonly used for scandium recovery. New technologies for scandium recovery such as selective leaching and solvent extraction are possible development direction in the future.
► This paper comprehensively reviews the metallurgical processes to recover scandium from various sources. ► Residues, tailings and waste liquors in the production of other metals are the resources for scandium. ► The most promising scandium resources for its production are bauxite and nickel laterite ores. ► Combined hydro- and pyro-metallurgical processes are commonly used for scandium recovery.
In the present study, microplastic-associated biofilms were cultivated in an urban lake and a reservoir using virgin expanded polystyrene (PS). The uptake of Pb(II) onto both natural (suspended ...particles and surficial sediment) and anthropogenic (virgin microplastics and microplastic-associated biofilms) solid substrates was investigated and compared as a function of contact time, pH, and ionic strength in batch adsorption experiments. The adsorption isotherms revealed that biofilms enhanced the adsorption capacity of Pb(II) onto microplastics; however, natural substrates still exhibited a higher capacity. Ionic strength and pH significantly influenced the adsorption of Pb(II) onto all of the solid substrates. Under neutral conditions, competitive adsorption of Pb(II) was observed between anthropogenic solid substrates and natural substrates, which may further alter the distribution of Pb(II) among these solid substrates. The combined toxicity tests of Pb(II) and each solid substrate were carried out using Daphnia magna, the results indicated biofilm enhanced the combined toxicity of Pb(II) and microplastics. Therefore, biofilms not only intensified the vector role of microplastics in the migration of heavy metals in freshwater, but also enhanced their combined toxicity, which may have further potential ecological risks to freshwater ecosystems.
Display omitted
•Microplastics act as anthropogenic vectors of Pb(II) in freshwater.•The biofilms enhanced the adsorption of Pb(II) onto microplastics.•The biofilms induced additional toxic effects of Pb(II) and microplastics.•Microplastics are necessary in evaluation of distribution and ecotoxicity of Pb(II).
Single‐atom catalysts (SACs), as homogeneous catalysts, have been widely explored for chemical catalysis. However, few studies focus on the applications of SACs in enzymatic catalysis. Herein, we ...report that a zinc‐based zeolitic‐imidazolate‐framework (ZIF‐8)‐derived carbon nanomaterial containing atomically dispersed zinc atoms can serve as a highly efficient single‐atom peroxidase mimic. To reveal its structure–activity relationship, the structural evolution of the single‐atom nanozyme (SAzyme) was systematically investigated. Furthermore, the coordinatively unsaturated active zinc sites and catalytic mechanism of the SAzyme are disclosed using density functional theory (DFT) calculations. The SAzyme, with high therapeutic effect and biosafety, shows great promises for wound antibacterial applications.
Single‐atom nanozyme: A ZIF‐8‐derived Zn–N–C single‐atom catalyst is an efficient single‐atom nanozyme (SAzyme). The SAzyme, which contains unsaturated Zn–N4 sites, shows excellent peroxidase‐like activity and high antibacterial activity against P. aeruginosa, and it is an effective antibacterial agent for wound treatment.
Understanding the movement of polycyclic aromatic hydrocarbons (PAHs) from emission sources to sediments is important for achieving long-term pollution control of PAHs in sediments. In this study, by ...exploring the correlation of individual PAHs concentrations (CPAHs) in Taihu Lake sediments reported in the past twenty years with their annual emissions (EPAHs) in the lake region, it was observed that mean concentrations of PAHs with low logKow (i.e., logKow≤4.00) in Taihu Lake sediments were correlated best with their emissions without lagging between the sediment sampling time and the PAHs emitting time. However, for PAHs with middle logKow (i.e., 4.00<logKow≤4.57) or high logKow (i.e., logKow>4.57), their mean concentrations in sediments were correlated best with the emissions of PAHs emitted 1 or 2 years before the sediment sampling time. The longer lagging time of PAHs with middle or high logKow from emission sources to lake sediments could be attributed to their retardation in soils and river sediments around the lake. Moreover, the retardation in soils and river sediments is dependent on PAHs logKow and degradation half-life, indicating the dependence of PAHs concentration in sediments on their environmental behaviors, including sorption and degradation. Kow dependent movement and the time lagging observed in Taihu Lake for PAHs from emission sources to sediments could be valuable for developing measures to control PAHs, especially for congeners with high logKow.
Display omitted
•Time lagging for PAHs from emission to sediments observed.•Lagging of PAHs attributed to retarding on soils and river sediments.•PAHs retarding on soils and river sediments is dependent on their logKow.•Movement hysteresis of PAHs is valuable for controlling PAHs into sediments.
PDF
