调控尖晶石Co^(3+)和Ni^(3+)表面密度来提高催化甲烷氧化活性（英文）

天然气资源丰富、价格低廉,因而被广泛用作燃料.天然气的主要成分是甲烷,未燃烧完的甲烷所产生的温室效应是二氧化碳的21倍,所带来的环境问题引起越来越多的研究者关注.但甲烷是最稳定的非极性有机小分子,C–H键能高达434 k J/mol,大多数催化剂很难将其在很低的温度在完全转化.C?H键的活化解离是催化甲烷燃烧最关键的一步,而活化C–H键方式主要有两大类:(1)均裂活化机制,一般用在贵金属催化剂上;(2)异裂活化机制,往往发生在过渡金属氧化物上.比较而言,贵金属催化剂,尤其是Pd,往往具有更优异的低温催化活性,但价格昂贵,从而限制了其广泛使用.因此,开发更加高效的非贵金属催化剂用于废气中未转化的甲烷完全氧化是亟待解决的问题.含有Co和Ni的尖晶石氧化物具有良好的催化甲烷燃烧活性,有望代替贵金属催化剂,但要求在低于400°C完全转化,仍具有一定挑战.另一方面,Ni^(3+)和Co^(3+)哪个是活性中心,还具有一定争议.因此,我们通过水热法和共沉淀法合成一系列表面暴露不同数目的Ni^(3+)和Co^(3+)来探究表面高氧化态Co和Ni跟活性之间的关系.XRD和TEM结果表明,相比于水热法合成的水热法合成的发生明显的晶格收缩现象,这是由于在尖晶石体相中大量小半径Ni^(3+)(0.053 nm)取代了大半径Co^(3+)(0.055 nm)所致.同时还发现,水热合成的尖晶石具有多孔纳米片层结构,相比于共沉淀法合成的尖晶石具有更大的比表面积,催化活性也更高.XPS分析发现,催化甲烷燃烧的活性随着表面含量增加而提高.结合文献分析和本文的实验结果推测,表面的Ni^(3+)和Co^(3+)都可作为解离C?H键的活性中心.水热60小时合成的纳米片表面的数量最多,所以具有最优异的催化性能,大约在280°C甲烷转化50%.当加入10%(体积比)的水,在高空速工况下对催化活性影响不大,主要是因为长时间水热合成的尖晶石表面缺陷少,对水的吸附弱,这可通过O 1s图谱得到印证.总之,这些研究结果能够给甲烷活化和开发更加高效和低成本催化剂一些启示.

Panoramic variation analysis of a family with neurodevelopmental disorders caused by biallelic loss-of-function variants in TMEM141,DDHD2,and LHFPL5

Highly clinical and genetic heterogeneity of neurodevelopmental disorders presents a major challenge in clinical genetics and medicine.Panoramic variation analysis is imperative to analyze the disease phenotypes resulting from multilocus genomic variation.Here,a Pakistani family with parental consanguinity was presented,characterized with severe intellectual disability(ID),spastic paraplegia,and deafness.Homozygosity mapping,integrated single nucleotide polymorphism(SNP)array,whole-exome sequencing,and whole-genome sequencing were performed,and homozygous variants in TMEM141(c.270G>A,p.Trp90^(*)),DDHD2(c.411+767_c.1249-327del),and LHFPL5(c.250delC,p.Leu84^(*))were identified.A Tmem141^(p.Trp90^(*)/p.Trp90^(*))mouse model was generated.Behavioral studies showed impairments in learning ability and motor coordination.Brain slice electrophysiology and Golgi staining demonstrated deficient synaptic plasticity in hippocampal neurons and abnormal dendritic branching in cerebellar Purkinje cells.Transmission electron microscopy showed abnormal mitochondrial morphology.Furthermore,studies on a human in vitro neuronal model(SH-SY5Y cells)with stable shRNA-mediated knockdown of TMEM141 showed deleterious effect on bioenergetic function,possibly explaining the pathogenesis of replicated phenotypes in the cross-species mouse model.Conclusively,panoramic variation analysis revealed that multilocus genomic variations of TMEM141,DDHD2,and LHFPL5 together caused variable phenotypes in patient.Notably,the biallelic loss-of-function variants of TMEM141 were responsible for syndromic ID.

Effect of structural characteristics on the transport characteristics of solid particles in the thermal storage and release system of circulating fluidized bed

Coal-fired power generation stands as the most economically viable modulating power source in present-day China.It holds the potential to offer prospective solutions to the challenges posed by the rapid expansion of intermittent,unpredictable,and unstable renewable energy sources.Solid particle thermal storage technology emerges as an effective means to enhance the flexibility of coal-fired circulating fluidized bed power units.To attain an optimized structure for the solid particle thermal storage and release system in circulating fluidized bed units,experimental research was conducted on a 0.1 MWth circulating fluidized bed test platform.This study delved into the impact of ash storage bin geometries and the shapes of their feed-discharge valves on the control properties of solid particle transportation.The experimental outcomes reveal that employing inverted m-shaped valve and dual U-shaped valves for feed control,alongside U-shaped valves and N-shaped valves for discharge control,both enable efficient and rapid storage and release of solid particles within the circulating fluidized bed.Under similar air distribution conditions,the inverted m-shaped valve exhibits lower conveying energy consumption than the dual U-shaped valves,while the N-shaped valve excels in control characteristics over the U-shaped valve.Furthermore,the inverted m-shaped valve and the N-shaped valve demonstrate optimal overflow port heights,and the ash storage bin exhibits an optimum height-to-diameter ratio.

Well-dispersed Mn/g-C_(3)N_(4)as bifunctional catalysts for selective epoxidation of olefins and carbon dioxide cycloaddition

Epoxidation is an important chemical process for the production of epoxides,key building blocks in chemical industry.Despite great efforts being made to facilitate this process,it remains a significant challenge to develop cost-effective,environmental-friendly,and selective catalysts.Herein,we reported a highly dispersed Mn supported by g-C_(3)N_(4)(Mn/g-C_(3)N_(4))with Mn loading up to 2.56 wt%.The Mn/g-CN_(4)exhibited satisfied catalytic performance for olefin epoxidation with excellent conversion(91%),high selectivity(93%)as well as outstanding recycling stability.Further analysis revealed the importance of Mn-N structure for the generation of active oxo-containing species and subsequent oxygen atom transfer.Besides,an efficient synthesis of cyclic carbonates from styrene epoxide and CO_(2)has been achieved(88%conversion,89%selectivity)based on the polar Mn-N coordinated characteristics of Mn/g-C_(3)N_(4)catalyst.

Bacterial biogeography in China and its association to land use and soil organic carbon

●6102 high-quality sequencing results of soil bacterial samples were re-analyzed.●The type of land use was the principal driver of bacterial richness and diversity.●SOC content is positively correlated with key bacteria and total nitrogen content.Soil organic carbon(SOC)is the largest pool of carbon in terrestrial ecosystems and plays a crucial role in regulating atmospheric CO_(2) concentrations.Identifying the essential relationship between soil bacterial communities and SOC concentration is complicated because of many factors,one of which is geography.We systematically re-analyzed 6102 high-quality bacterial samples in China to delineate the bacterial biogeographic distribution of bacterial communities and identify key species associated with SOC concentration at the continental scale.The type of land use was the principal driver of bacterial richness and diversity,and we used machine learning to calculate its influence on microbial composition and their co-occurrence relationship with SOC concentration.Cultivated land was much more complex than forest,grassland,wetland and wasteland,with high SOC concentrations tending to enrich bacteria such as Rubrobacter,Terrimonas and Sphingomona.SOC concentration was positively correlated with the amounts of soil total nitrogen and key bacteria Xanthobacteraceae,Streptomyces and Acidobacteria but was negatively correlated with soil pH,total phosphorus and Micrococcaceae.Our study combined the SOC pool with bacteria and indicated that specific bacteria may be key factors affecting SOC concentration,forcing us to think about microbial communities associated with climate change in a new way.

Alteration of dominant cyanobacteria in different bloom periods caused by abiotic factors and species interactions

Freshwater cyanobacterial blooms have drawn public attention because they threaten the safety of water resources and human health worldwide.Heavy cyanobacterial blooms outbreak in Lake Taihu in summer annually and vanish in other months.To find out the factors impacting the cyanobacterial blooms,the present study measured the physicochemical parameters of water and investigated the composition of microbial community using the 16S rRNA gene and internal transcribed spacer amplicon sequencing in the months with or without bloom.The most interesting finding is that two major cyanobacteria,Planktothrix and Microcystis,dramatically alternated during a cyanobacterial bloom in 2016,which is less mentioned in previous studies.When the temperature of the water began increasing in July,Planktothrix appeared first and showed as a superior competitor for M.aeruginosa in NO3^−-rich conditions.Microcystis became the dominant genus when the water temperature increased further in August.Laboratory experiments confirmed the influence of temperature and the total dissolved nitrogen(TDN)form on the growth of Planktothrix and Microcystis in a co-culture system.Besides,species interactions between cyanobacteria and non-cyanobacterial microorganisms,especially the prokaryotes,also played a key role in the alteration of Planktothrix and Microcystis.The present study exhibited the alteration of two dominant cyanobacteria in the different bloom periods caused by the temperature,TDN forms as well as the species interactions.These results helped the better understanding of cyanobacterial blooms and the factors which contribute to them.

Comparison of the toxicity of silver nanoparticles and silver ions on the growth of terrestrial plant model Arabidopsis thaliana

Silver nanoparticles （AgNPs） are one of the most widely used nanomaterials, but the mechanism of AgNP toxicity in terrestrial plants is still unclear. We compared the toxic effects of AgNPs and Ag＋ on Arabidopsis thaliana at the physiological, ultrastructural and molecular levels. AgNPs did not affect seed germination; however, they showed stronger inhibitory effect on root elongation than Ag＋ . The results of transmission electron microscopy and metal content analysis showed that AgNPs could be accumulated in leaves. These absorbed AgNPs disrupted the thylakoid membrane structure and decreased chlorophyll content, which can inhibit plant growth. By comparison, a small amount of Ag＋ was absorbed by seedlings, and it did not pronouncedly affect chloroplast structure and other metal ion absorption as AgNPs did. Compared with Ag＋ , AgNPs could alter the transcription of antioxidant and aquaporin genes, indicating that AgNPs changed the balance between the oxidant and antioxidant systems, and also affected the homeostasis of water and other small molecules within the plant body. All the data from physiological, ultrastructural and molecular levels suggest that AgNPs were more toxic than Ag＋ .

Review of Geostationary Interferometric Infrared Sounder

To measure the global atmospheric three-dimensional distribution and change of temperature and humidity is one of the key areas in atmospheric remote sensing detection; it is also a new research and development direction in the field of meteorological satellite application. As a main element of China second generation of geostationary meteorological satellite Fengyun 4 （FY-4）, which was launched on Dec. 11, 2016, the Geostationary Interferometric Infrared Sounder （GIIRS） is the first interferometric infrared sounder working on the international geostationary orbit. It is used for vertical atmospheric sounding and gains atmospheric temperature, humidity, and disturbances. The combination of Fourier transform spectrometer technology and infrared detectors makes GIIRS have high spectral resolution and large coverage over spatial areas. With this kind of instrument, meteoro- logical satellites can improve the capabilities for severe weather event monitoring and numerical weather prediction. Here a concise review of the GIIRS development project, including its history, missions and functions, technical design, key technologies, system integration, calibration and in-orbit operation status, etc., is presented.

Sinter-resistant and high-efficient Pt/CeO2/NiAl2O4/Al2O3@SiO2 model catalysts with “composite energy traps”

The stability of nanosized catalysts at high temperature is still a challenging topic and is a crucial criterion to evaluate their suitability for industrial use. Currently, the strategy to improve the high-temperature stability of nano-sized catalysts is to restrict the migration of particles on the surface, which, however, lacks theoretical knowledge and directions. Herein, we reported a new approach that can effectively inhibit the migration and agglomeration of supported nanoparticles by fabrication of a model catalyst Pt/CeO2/NiAl2O4/Al2O3@SiO2. This catalyst is highly stable with the microstructure unchanged even after being aged at 1000 °C. Density functional theory calculations indicate that two types of confinement effects exist in the catalyst and their mechanisms were well explained from the viewpoint of "energy traps" which can also be applied to other supported catalysts.

Biocompatible hierarchical zwitterionic polymer brushes with bacterial phosphatase activated antibacterial activity

Hierarchical polymer brushes have been considered as an effective and promising method for preventing implant-associated infections via multiple antibacterial mechanisms.Herein,a bacterial phosphatase re-sponsive surface with hierarchical zwitterionic structures was developed for timely dealing with the poly-meric implant-associated bacterial infection.The hierarchical polymeric architecture was subtly realized on model polypropylene(PP)substrate by sequential photo living grafting of poly(2-(dimethylamino)ethyl methacrylate(PDMAEMA)bottom layer and zwitterionic poly(sulfobetaine methacrylate)(PSBMA)upper layer,followed by the conversion of the PDMAEMA into the zwitterionic structure via succes-sive quaternization and phosphorylation reactions.Owing to shielding the bottom polycations,the hi-erarchical zwitterionic polymer brushes guaranteed the surface with the optimal biocompatibility under the normal physiological environment.Once bacteria are invaded,the surface bactericidal activity of the bottom layer can be rapidly and automatically activated owing to the transition triggered by bacterial phosphatase from zwitterion to polycation.Additionally,ameliorated by the upper layer,the hierarchical surface showed obvious adhesion resistance to dead bacterial cells and notably migrated the cytotoxic-ity of exposed polycation after completion of the bactericidal task.As a proof-of-principle demonstration,this self-adaptive hierarchical surface with sensitive bacterial responsiveness and biocompatibility showed great potential in combating hernia mesh-related infection.This work provides a promising and universal strategy for the on-demand prevention of medical device-associated infections.

Reading-related Brain Function Restored to Normal After Articulation Training in Patients with Cleft Lip and Palate:An fMRI Study

Cleft lip and/or palate(CLP)are the most common craniofacial malformations in humans.Speech problems often persist even after cleft repair,such that follow-up articulation training is usually required.However,the neural mechanism behind effective articulation training remains largely unknown.We used fMRI to investigate the differences in brain activation,functional connectivity,and effective connectivity across CLP patients with and without articulation training and matched normal participants.We found that training promoted task-related brain activation among the articulation-related brain networks,as well as the global attributes and nodal efficiency in the functional-connectivity-based graph of the network.Our results reveal the neural correlates of effective articulation training in CLP patients,and this could contribute to the future improvement of the post-repair articulation training program.

Novel variants in LAMA3 and COL7A1 and recurrent variant in KRT5 underlying epidermolysis bullosa in five Chinese families

Epidermolysis bullosa(EB)is a group of clinically and genetically heterogeneous diseases characterized by trauma-induced mucocutaneous fragility and blister formation.Here,we investigated five Chinese families with EB,and eight variants including a novel nonsense variant(c.47G>A,p.W16*)in LAMA3,a known recurrent variant(c.74C>T,p.P25L)in KRT5,2 novel(c.2531T>A,p.V844E;c.6811_6814del,p.R2271fs)and 4 known(c.6187C>T,p.R2063W;c.7097G>A,p.G2366D;c.8569G>T,p.E2857*;c.3625_3635del,p.S1209fs)variants in COL7A1 were detected.Notably,this study identified a nonsense variant in LAMA3 that causes EB within the Chinese population and revealed that this variant resulted in a reduction in LAMA3 mRNA and protein expression levels by nonsense-mediated mRNA decay.Our study expands the mutation spectra of Chinese patients with EB.

Phenotypic and genetic characterization of novel variant in the NF1 gene underlying neurofibromatosis type 1 in five Chinese families

Dear Editor,Neurofibromatosis type 1(NF1;von Recklinghausen neurofibromatosis;OMIM 162200)is a neurocutaneous genetic disorder that affects approximately one in 2,500 people worldwide(Huson et al.,1989).NF1 is characterized by wide clinical variability,including multiple café-au-lait macules(CALMs),fibromatous tumors,axillary or inguinal freckling,Lisch nodules(iris hamartomas),skeletal anomalies,and cognitive impairments(Monroe et al.,2017).