[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significant...[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significantly reduce energy consumption,pollution emissions and reliance on fossil fuels.Bipolar plates are the major part and key component of PEMFCs stack,which provide mechanical strength,collect and conduct current segregate oxidants and reduce agents.They contribute 70-80%weight and 20-30%cost of a whole stack,while significantly affecting the power density.There are three types plates,including metal bipolar plate,graphite bipolar plate and composite bipolar plate.Stainless steel bipolar plates,as one of metal bipolar plate,exhibit promising manufacturability,competitive cost and durability among various metal materials.However,stainless steel would be corroded in the harsh acid(pH 2-5)and humid PEMFCs environment,whereas the leached ions will contaminate the membrane.In addition,the passivated film formed on the surface will increase the interfacial contact resistance(ICR).In order to improve the corrosion resistance and electrical conductivity of steel bipolar plates,surface coatings are essential.Metal nitride coatings,metal carbide coatings,polymer coatings and carbon-based coatings have been introduced in recent years.Carbon-based coatings,mainly including a-C(amorphous Carbon),Ta-C(Tetrahedral amorphous carbon)and DLC(diamond-like carbon),have attracted considerable attention from both academia and industry,owing to their superior performance,such as chemical inertness,mechanical hardness and electrical conductivity.However,Ta-C films as protective coating of PEMFCs have been rarely reported,due to the difficulty in production for industrial application.In this paper,multi-layer Ta-C composite films were produced by using customized industrial-scale vacuum equipment to address those issues.[Methods]Multiple layered Ta-C coatings were prepared by using PIS624 equipment,which assembled filtered cathodic arc evaporation,ion beam and magnetron sputtering into one equipment,while SS304 and silicon specimens were used as substrate for testing and analysis.Adhesion layer and intermediate layer were deposited by using magnetron sputtering at deposition temperature of 150℃and pressure of 3×10^(−1) Pa,while the sputtering current was set to be 5 A and bias power to be 300 V.The Ta-C layer was coated at arc current of 80-100 A,bias voltage of 1500 V and gas flow of 75 sccm.A scanning electron microscope(CIQTEK SEM3200)was used to characterize surface morphology,coating structure and cross-section profile of the coatings.Raman spectrometer(LabRam HR Evolution,HORIBA JOBIN YVON)was used to identify the bonding valence states.Electrochemical tests were performed by using an electrochemical work station(CHI760,Shanghai Chenhua Instrument Co.,Ltd.),with the traditional three electrode system,where saturated Ag/AgCl and platinum mesh were used as the reference electrode and counter electrode,respectively.All samples were mounted in plastic tube and sealed with epoxy resin,with an exposure area of 2.25 cm^(2),serving as the working electrode.Electrochemical measurements were carried out in simulated PEMFCs cathode environment in 0.5 mol·L^(−1) H_(2)SO_(4)+5 ppm F−solution,at operating temperature of 70℃.As the cathode environment was harsher than the anode environment,all the samples are stabilized at the open-circuit potential(OCP)for approximately 30 min before the EIS measurements.ICR between bipolar plates and GDL was a key parameter affecting performance of the PEMFCs stack.The test sample sandwiched between 2 pieces of carbon paper(simulate gas diffusion layer,GDL)was placed between 2 gold-plated copper electrodes at a compaction pressure of 1.4 MPa,which was considered to be the conventional compaction pressure in the PEMFCs.Under the same conditions,the resistance of a single carbon paper was measured as well.The ICR was calculated according to the formula ICR=1/2(R2−R1)×S,where S was the contact area between GDL and coated stainless steel BPPs.All data of ICR were measured three times for averaging.[Results]The coatings deposited by filtered cathodic arc technology were compact and smooth,which reduced coating porosity and favorable to corrosion resistance.The coating thickness of adhesion and intermediate layers were 180 nm,while the protective Ta-C coating thickness was about 300 nm,forming multiple coating to provide stronger protection for metal bipolar plates.Cr,Ti,Nb and Ta coatings were selected as adhesion layers for comparison.According to electrochemical test,Ta and Nb coatings have higher corrosion resistance.However,Ta and Nb materials would be costly when they are used for mass production.Relatively,Cr and Ti materials were cost effective.Hence,a comprehensive assessment was indispensable to decide the materials to be selected as adhesion layer.Ta-TiN and Ti-TiN combined adhesion and intermediate layer exhibited stronger corrosion resistance,with the corrosion current to be less than 10^(−6) A·cm^(−2).Ta-C protective coating deposited by using filtered cathodic arc technology indicated displayed higher corrosion resistance,with the average corrosion density to be about 1.26×10^(−7) A·cm^(−2).Ta-C coating also shown larger contact angle,with the highest hydrophobicity,which was one of the important advantages for Ta-C,in terms of corrosion resistance.According to Raman spectroscopy,the I(D)/I(G)=549.8/1126.7=0.487,with the estimated fraction of sp^(3) bonding to be in the range of 5154%.The intermediate layer TiN has higher conductivity than the CrN layer.Considering cost,corrosion performance and ICR result,the Ti-TiN layer combination is recommended for industrial scale application.[Conclusions]Multiple layer coating structure of Ta-C film had stronger corrosion resistance;with more than 50%sp^(3) content,while it also had larger water contact angle and higher corrosion resistance than DLC film.The filtered arcing deposition technology was able to make the film to be more consistent and stable than normal arcing technology in terms of the preparation of Ta-C.The coating displayed corrosion density of 1.26×10^(−7) A·cm^(−2) and ICR of less than 5 mΩ·cm^(2),far beyond technical target of 2025 DOE(US Department of Energy).This indicated that the mass-production scale coating technology for PEMFC bipolar plates is highly possible.展开更多
Osteogenic ability impairment and myelosuppression are common complications of chemotherapy and many chemotherapeutics can affect the skeletal system.Skeletal system protection is necessary for cancer chemotherapy.In ...Osteogenic ability impairment and myelosuppression are common complications of chemotherapy and many chemotherapeutics can affect the skeletal system.Skeletal system protection is necessary for cancer chemotherapy.In this study,osteogenic growth peptide(OGP)and tetrahedral framework nucleic-acid nanostructures(tFNAs)are combined to form a peptide-DNA complex OGP-tFNAs,which aims to combine the positive biological effect on tissue protection and regeneration.The bone marrow protection and bone formation effect of OGP-tFNAs are investigated in chemotherapy-induced myelosuppressive mice.The results show that OGP-tFNAs could reduce the cell damage degree from 5-fluorouracil(5-FU)in vitro and maintained the osteogenic differentiation potential.Furthermore,OGP-tFNAs accelerate bone defect regeneration in myelosuppressive mice.In conclusion,OGP-tFNAs could protect the osteogenic differentiation potential of bone marrow stromal cells(BMSCs)from 5-FU injury and maintain the bone formation ability of myelosuppressive mice suffering from chemotherapy.展开更多
Neuropathic pain(NP)is one of the most common pathological pain types and is associated with limited treatment options;moreover,it affects patients’quality of life and causes a heavy social burden.Despite the emphasi...Neuropathic pain(NP)is one of the most common pathological pain types and is associated with limited treatment options;moreover,it affects patients’quality of life and causes a heavy social burden.Despite the emphasis on inhibiting neuronal apoptosis to relieve NP,the crucial role of a neuroinflammation is often overlooked.Therefore,refocusing on the regulation of microglia polarization to create a more conducive environment for neuron holds great potential in NP treatment.In recent years,small interfering RNAs(siRNAs)had become an attractive therapeutic option.However,an efficient loading and delivery system for siRNA is still in lack.In our study,a nanostructured tetrahedral framework nucleic acid loaded with the small interfering RNA C–C chemokine receptor 2(T-siCCR2)was successfully designed and synthesized for use in NP rat model in vivo and in a lipopolysaccharide(LPS)-induced inflammatory environment in vitro.This nanoscale complex is endowed with structural stability and satisfactory delivery efficiency while assuring the silencing effect of siRNA-CCR2.In vivo,T-siCCR2 treatment exhibited favorable effects on pain relief and functional improvement in the NP animal model by directly targeting microglia.In vitro,T-siCCR2 counteracts LPS-induced inflammation by inhibiting the differentiation of microglia toward the M1 phenotype,thus playing a neuroprotective role.RNA sequencing was subsequently performed to elucidate the underlying mechanism involved.These results indicate that T-siCCR2 may serve as a potential treatment option for NP in the future.展开更多
Diabetic kidney disease(DKD)is recognized as a severe complication in the development of diabetes mellitus(DM),posing a significant burden for global health.Major characteristics of DKD kidneys include tubulointerstit...Diabetic kidney disease(DKD)is recognized as a severe complication in the development of diabetes mellitus(DM),posing a significant burden for global health.Major characteristics of DKD kidneys include tubulointerstitial oxidative stress,inflammation,excessive extracellular matrix deposition,and progressing renal fibrosis.However,current treatment options are limited and cannot offer enough efficacy,thus urgently requiring novel therapeutic approaches.Tetrahedral framework nucleic acids(tFNAs)are a novel type of self-assembled DNA nanomaterial with excellent structural stability,biocompatibility,tailorable functionality,and regulatory effects on cellular behaviors.In this study,we established an in vitro high glucose(HG)-induced human renal tubular epithelial cells(HK-2 cells)pro-fibrogenic model and explored the antioxidative,anti-inflammatory,and antifibrotic capacity of tFNAs and the potential molecular mechanisms.tFNAs not only effectively alleviated oxidative stress through reactive oxygen species(ROS)-scavenging and activating the serine and threonine kinase(Akt)/nuclear factor erythroid 2-related factor 2(Nrf2)/heme oxygenase-1(HO-1)signaling pathway but also inhibited the production of proinflammatory factors such as tumor necrosis factor(TNF-α),interleukin-1β(IL-1β),and interleukin-6(IL-6)in diabetic HK-2 cells.Additionally,tFNAs significantly downregulated the expression of Collagen I andα-smooth muscle actin(α-SMA),two representative biomarkers of pro-fibrogenic myofibroblasts in the renal tubular epithelial-mesenchymal transition(EMT).Furthermore,we found that tFNAs exerted this function by inhibiting the Wnt/β-catenin signaling pathway,preventing the occurrence of EMT and fibrosis.The findings of this study demonstrated that tFNAs are naturally endowed with great potential to prevent fibrosis progress in DKD kidneys and can be further combined with emerging pharmacotherapies,providing a secure and efficient drug delivery strategy for future DKD therapy.展开更多
We theoretically study the effect of a uniform orbital magnetic field on spin waves in a triangular lattice tetrahedral antiferromagnetic insulator without spin–orbit coupling. Through symmetry analysis and microscop...We theoretically study the effect of a uniform orbital magnetic field on spin waves in a triangular lattice tetrahedral antiferromagnetic insulator without spin–orbit coupling. Through symmetry analysis and microscopic calculation, we show that the optical spin wave mode at the Brillouin zone center can acquire a small orbital magnetic moment, although it exhibits no magnetic moment from the Zeeman coupling. Our results are potentially applicable to intercalated van der Waals materials and twisted double-bilayer graphene.展开更多
Hyperglycemia resulting from diabetes mellitus(DM)exacerbates osteoporosis and fractures,damaging bone regeneration due to impaired healing capacity.Stem cell therapy offers the potential for bone repair,accelerating ...Hyperglycemia resulting from diabetes mellitus(DM)exacerbates osteoporosis and fractures,damaging bone regeneration due to impaired healing capacity.Stem cell therapy offers the potential for bone repair,accelerating the healing of bone defects by introducing stem cells with osteogenic differentiation ability.Dental follicle stem cells(DFSCs)are a newly emerging type of dental stem cells that not only have the potential for multipotent differentiation but also hold easy accessibility and can stand longterm storage.However,DM-associated oxidative stress and inflammation elevate the risk of DFSCs dysfunction and apoptosis,diminishing stem cell therapy efficacy.Recent nanomaterial advances,particularly in DNA nanostructures like tetrahedral framework nucleic acids(tFNAs),have been promising candidates for modulating cellular behaviors.Accumulating experiments have shown that tFNAs’cell proliferation and migration-promoting ability and induce osteogenic differentiation of stem cells.Meanwhile,tFNAs can scavenge reactive oxygen species(ROS)and downregulate the secretion of inflammatory factors by inhibiting various inflammation-related signaling pathways.Here,we applied tFNAs to modify DFSCs and observed enhanced osteogenic differentiation alongside ROS scavenging and anti-inflammatory effects mediated by suppressing the ROS/mitogen-activated protein kinases(MAPKs)/nuclear factor kappa-B(NF-κB)signaling pathway.This intervention reduced stem cell apoptosis,bolstering stem cell therapy efficacy in DM.Our study establishes a simple yet potent tFNAs-DFSCs system,offering potential as a bone repair agent for future DM treatment.展开更多
This paper presents a reconstruction algorithm to build a surface mesh approximating an object from an unorganized point sampling of the boundary object. It combines 3D Delaunay tetrahedralization and mesh-growing met...This paper presents a reconstruction algorithm to build a surface mesh approximating an object from an unorganized point sampling of the boundary object. It combines 3D Delaunay tetrahedralization and mesh-growing method and uses only once Delau- nay triangulation. It begins with 3D Delaunay triangulation of the sampling. Then initialize the surface mesh with seed facets se- lected from Delaunay triangulation. Selection is based on the angle formed by the circumscribing ball of incident tetrahedral. Finally, grow until complete the surface mesh based on some heuristic rules. This paper shows several experimental results that demonstrate this method can handle open and close surfaces and work efficiently on various object topologies except non-manifold surface with self-intersections. It can reproduce even the smallest details of well-sampled surfaces but not work properly in every under-sampled situation that point density is too low.展开更多
For storing and modeling three-dimensional(3D)topographic objects(e.g.buildings,roads,dykes,and the terrain),tetrahedralizations have been proposed as an alternative to boundary representations.While in theory they ha...For storing and modeling three-dimensional(3D)topographic objects(e.g.buildings,roads,dykes,and the terrain),tetrahedralizations have been proposed as an alternative to boundary representations.While in theory they have several advantages,current implementations are either not space efficient or do not store topological relationships(which makes spatial analysis and updating slow,or require the use of an expensive 3D spatial index).We discuss in this paper an alternative data structure for storing tetrahedralizations in a database management system(DBMS).It is based on the idea of storing only the vertices and stars of edges;triangles and tetrahedra are represented implicitly.It has been used previously in main memory,but not in a DBMS.We describe how to modify it to obtain an efficient implementation in a DBMS,and we describe how it can be used for modeling 3D topography.As we demonstrate with different real-world examples,the structure is compacter than known alternatives,it permits us to store attributes for any primitives,and has the added benefit of being topological,which permits us to query it efficiently.The structure can be easily implemented in most DBMS(we describe our implementation in PostgreSQL),and we present some of the engineering choices we made for the implementation.展开更多
Local mesh refinement is one of the key steps in the implementations of adaptive finite element methods. This paper presents a parallel algorithm for distributed memory parallel computers for adaptive local refinement...Local mesh refinement is one of the key steps in the implementations of adaptive finite element methods. This paper presents a parallel algorithm for distributed memory parallel computers for adaptive local refinement of tetrahedral meshes using bisection. This algorithm is used in PHG, Parallel Hierarchical Grid Chttp：//lsec. cc. ac. cn/phg/）, a toolbox under active development for parallel adaptive finite element solutions of partial differential equations. The algorithm proposed is characterized by allowing simukaneous refinement of submeshes to arbitrary levels before synchronization between submeshes and without the need of a central coordinator process for managing new vertices. Using the concept of canonical refinement, a simple proof of the independence of the resulting mesh on the mesh partitioning is given, which is useful in better understanding the behaviour of the biseetioning refinement procedure.展开更多
Osteoarthritis, a disorder characterized by articular cartilage deterioration, varying degrees of inflammation, and chondrocyte apoptosis, is the most common chronic joint disease. To slow or reverse its progression, ...Osteoarthritis, a disorder characterized by articular cartilage deterioration, varying degrees of inflammation, and chondrocyte apoptosis, is the most common chronic joint disease. To slow or reverse its progression, inflammation should be inhibited, and chondrocyte proliferation should be promoted. Tetrahedral framework nucleic acids can be internalized by chondrocytes(even inflammatory chondrocytes) and can enhance their proliferation and migration. Wogonin, a naturally occurring flavonoid,suppresses oxidative stress and inhibits inflammation. In this study, tetrahedral framework nucleic acids were successfully selfassembled and used to load wogonin. We confirmed the effective formation of tetrahedral framework nucleic acid/wogonin complexes by dynamic light scattering, zeta potential analysis, transmission electron microscopy, and fluorescence spectrophotometry. Tetrahedral framework nucleic acids, wogonin, and especially tetrahedral framework nucleic acid/wogonin complexes effectively alleviated inflammation in vitro and in vivo and prevented cartilage destruction. In addition, these materials remarkably downregulated the expression of inflammatory mediators and matrix metalloproteinases, upregulated chondrogenic markers, and promoted tissue inhibitor of metalloproteinase 1 and B-cell lymphoma 2 expression. In vivo, after treatment with tetrahedral framework nucleic acid/wogonin complexes, the bone mineral density in regenerated tissues was much higher than that found in the untreated groups. Histologically, the complexes enhanced new tissue regeneration, significantly suppressed chondrocyte apoptosis, and promoted chondrogenic marker expression. They also inhibited cell apoptosis, increased chondrogenic marker expression, and suppressed the expression of inflammatory mediators in osteoarthritis. Therefore, we believe that tetrahedral framework nucleic acid/wogonin complexes can be used as an injectable form of therapy for osteoarthritis.展开更多
The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN appli...The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN application is automatic creating data structure. Although a raster algorithm has been introduced by some authors, the problems in accuracy, memory requirement, speed and integrity are still existent. In this paper, the raster algorithm is completed and a vector algorithm is presented after a 3-D data model and structure of TEN have been introducted. Finally, experiment, conclusion and future work are discussed.展开更多
Incorporation of heteroatoms into the framewo rk of zeolites has become a significant strategy to improve their performance in catalysis and adsorption,because the obtained heteroatom zeolites exhibit quite different ...Incorporation of heteroatoms into the framewo rk of zeolites has become a significant strategy to improve their performance in catalysis and adsorption,because the obtained heteroatom zeolites exhibit quite different properties from the conventional aluminosilicate zeolites in aspects of surface acidity,pore structures,particle size and so on.In this review,the progress on the heteroatom zeolites including their synthesis and application is highlighted.First,the recent advance on the design and synthesis of different heteroatom zeolites is summarized.Special emphasis is placed on the introduction and comparison of three typical methods,including the direct synthesis,post synthesis and improved direct synthesis,for the traditional heteroatom zeolites(such as TS-1,Sn-MFI,Sn-β) and newly-reported heteroatom zeolites(such as W-MFI,Mo-MFI).According to their intrinsic characteristics,the application of heteroatom zeolites in diverse fields,such as production of fine chemicals,air pollution control and biomass conversion is then discussed.Finally,the challenges and perspective on the future development of heteroatom zeolites in low-cost preparation and practical application are proposed.展开更多
In this work,the high temperature friction mechanism of the tetrahedral amorphous carbon(ta-C)film was elucidated.The multilayer ta-C film with alternating hard and soft sub-layers exhibited a low friction coefficient...In this work,the high temperature friction mechanism of the tetrahedral amorphous carbon(ta-C)film was elucidated.The multilayer ta-C film with alternating hard and soft sub-layers exhibited a low friction coefficient of 0.14 at 400℃ before a sudden failure occurred at 4600 cycles.The wear failure was attributed to the gradual consumption of the ta-C film at the contact region.The design of a hard or soft top layer effectively regulated the high temperature friction properties of the multilayer ta-C.The addition of a hard top layer contributed to a low friction coefficient(0.11)and a minor wear rate(4.0×10^(-7)mm^(3)/(N m)),while a soft top layer deteriorated the lubrication effect.It was proposed that the passivation of dangling bonds at the sliding interface dominated the low-friction mechanism of the ta-C film at high temperature,while the friction induced graphitization and the formation of sp^(2)-rich carbonaceous transfer layer triggered C-C inter-film bonding,resulting in serious adhesion force and lubrication failure.Moreover,the multilayer ta-C film with hard top layer obtained excellent friction performance within 500℃,while the high temperature induced oxidation and volatilization of carbon atoms led to the wear failure at 600℃.展开更多
With the emergence of DNA nanotechnology in the 1980s, self-assembled DNA nanostructures have attracted considerable attention worldwide due to their inherent biocompatibility, unsurpassed programmability, and versati...With the emergence of DNA nanotechnology in the 1980s, self-assembled DNA nanostructures have attracted considerable attention worldwide due to their inherent biocompatibility, unsurpassed programmability, and versatile functions. Especially promising nanostructures are tetrahedral framework nucleic acids(t FNAs), first proposed by Turberfield with the use of a one-step annealing approach. Benefiting from their various merits, such as simple synthesis, high reproducibility, structural stability, cellular internalization, tissue permeability, and editable functionality, t FNAs have been widely applied in the biomedical field as threedimensional DNA nanomaterials. Surprisingly, t FNAs exhibit positive effects on cellular biological behaviors and tissue regeneration,which may be used to treat inflammatory and degenerative diseases. According to their intended application and carrying capacity,t FNAs could carry functional nucleic acids or therapeutic molecules through extended sequences, sticky-end hybridization,intercalation, and encapsulation based on the Watson and Crick principle. Additionally, dynamic t FNAs also have potential applications in controlled and targeted therapies. This review summarized the latest progress in pure/modified/dynamic t FNAs and demonstrated their regenerative medicine applications. These applications include promoting the regeneration of the bone,cartilage, nerve, skin, vasculature, or muscle and treating diseases such as bone defects, neurological disorders, joint-related inflammatory diseases, periodontitis, and immune diseases.展开更多
Obesity-induced insulin resistance is the hallmark of metabolic syndrome,and chronic,low-grade tissue inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells.Current...Obesity-induced insulin resistance is the hallmark of metabolic syndrome,and chronic,low-grade tissue inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells.Current therapeutic approaches lack efficacy and immunomodulatory capacity.Thus,a new therapeutic approach is needed to prevent chronic inflammation and alleviate insulin resistance.Here,we synthesized a tetrahedral framework nucleic acid(tFNA)nanoparticle that carried resveratrol(RSV)to inhibit tissue inflammation and improve insulin sensitivity in obese mice.The prepared nanoparticles,namely tFNAs-RSV,possessed the characteristics of simple synthesis,stable properties,good water solubility,and superior biocompatibility.The tFNA-based delivery ameliorated the lability of RSV and enhanced its therapeutic efficacy.In high-fat diet(HFD)-fed mice,the administration of tFNAs-RSV ameliorated insulin resistance by alleviating inflammation status.tFNAs-RSV could reverse M1 phenotype macrophages in tissues to M2 phenotype macrophages.As for adaptive immunity,the prepared nanoparticles could repress the activation of Th1 and Th17 and promote Th2 and Treg,leading to the alleviation of insulin resistance.Furthermore,this study is the first to demonstrate that tFNAs,a nucleic acid material,possess immunomodulatory capacity.Collectively,our findings demonstrate that tFNAs-RSV alleviate insulin resistance and ameliorate inflammation in HFD mice,suggesting that nucleic acid materials or nucleic acid-based delivery systems may be a potential agent for the treatment of insulin resistance and obesity-related metabolic diseases.展开更多
Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentant...Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera （G. Don） Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi （Sweet） Pojarkova range from 37.67 μm to 61.06μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding ＆ Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.展开更多
In turbulence modeling, the RNG and Realizable models have important improvements in the turbulent production and dissipation terms in comparison to the Standard. The selection of the appropriate turbulence model has ...In turbulence modeling, the RNG and Realizable models have important improvements in the turbulent production and dissipation terms in comparison to the Standard. The selection of the appropriate turbulence model has an impact on the convergence and solution in STRs, and they are used in mixing, multiphase modeling or as starting solution of transient models as DES and LES. Although there are several studies with the pitched blade turbine(PBT) impeller, most of them used the Standard model as representative of all k–ε models, using structured hexahedral grids composed of low number of cells, and in some cases under axial symmetry assumptions.Accordingly, in this work the assessment of the Standard, RNG and Realizable models to describe the turbulent flow field of this impeller, using the Multiple Reference Frame(MRF) and Sliding Mesh(SM) approaches with tetrahedral domains in dense grids, is presented. This kind of cell elements is especially suitable to reproduce complex geometries. Flow velocities and turbulent parameters were verified experimentally by PIV and torque measurements. The three models were capable of predicting fairly the pumping number, the power number based on torque, and velocities. Although the RNG improved the predictions of the turbulent kinetic energy and dissipation rate, the Realizable model presented better performance for both approaches. All models failed in the prediction of the total dissipation rate, and a dependence of its value on the number of cells for the MRF was found.展开更多
The microstructure and properties of tetrahedral amorphous carbon (ta-C) films deposited by the filtered cathodic vacuum arc technology has been investigated by visible Raman spectroscopy, AFM and Nano-indentor. The R...The microstructure and properties of tetrahedral amorphous carbon (ta-C) films deposited by the filtered cathodic vacuum arc technology has been investigated by visible Raman spectroscopy, AFM and Nano-indentor. The Raman spectra have been fitted with a single skewed Lorentzian lineshape described by BWF function defining coupling coefficient, which characterizes the degree of asymmetry and is correlated with the sp3 content. When the substrate bias is -80 V, the sp3 content is the most and simultaneously the coupling coefficient is the least, following with the minimum root mean square surface roughness (Rq=0.23 nm) and the highest hardness (51.49 GPa), Young′s modulus (512.39 GPa), and critical scratching load (11.72 mN). As the substrate bias is increased or decreased, the sp3 content and other properties lower correspondingly.展开更多
Synthetic antigen-encoding mRNA plays an increasingly significant role in tumor vaccine technology owing to its antigen-specific immune-activation. However, its immune efficacy is challenged by inferior delivery effic...Synthetic antigen-encoding mRNA plays an increasingly significant role in tumor vaccine technology owing to its antigen-specific immune-activation. However, its immune efficacy is challenged by inferior delivery efficiency and demand for suitable adjuvants. Here, we develop a novel mRNA nanovaccine based on a multifunctional nanocapsule, which is a dual-adjuvant formulation composed of cytosine-phosphateguanine motifs loaded tetrahedral framework nucleic acid(CpG-tFNA) and an immunopeptide murine β-defensin 2(mDF2β). This m RNA nanovaccine successfully achieves intracellular delivery, antigen expression and presentation of dendritic cells, and proliferation of antigen-specific T cells. In a tumor prophylactic vaccination model, it exerts an excellent inhibitory effect on lymphoma occurrence through cellular immunity. This mRNA nanovaccine has promising prophylactic applications in tumors and many other diseases.展开更多
基金Major Science and technology projects of Anhui Province (202103a05020003)。
文摘[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significantly reduce energy consumption,pollution emissions and reliance on fossil fuels.Bipolar plates are the major part and key component of PEMFCs stack,which provide mechanical strength,collect and conduct current segregate oxidants and reduce agents.They contribute 70-80%weight and 20-30%cost of a whole stack,while significantly affecting the power density.There are three types plates,including metal bipolar plate,graphite bipolar plate and composite bipolar plate.Stainless steel bipolar plates,as one of metal bipolar plate,exhibit promising manufacturability,competitive cost and durability among various metal materials.However,stainless steel would be corroded in the harsh acid(pH 2-5)and humid PEMFCs environment,whereas the leached ions will contaminate the membrane.In addition,the passivated film formed on the surface will increase the interfacial contact resistance(ICR).In order to improve the corrosion resistance and electrical conductivity of steel bipolar plates,surface coatings are essential.Metal nitride coatings,metal carbide coatings,polymer coatings and carbon-based coatings have been introduced in recent years.Carbon-based coatings,mainly including a-C(amorphous Carbon),Ta-C(Tetrahedral amorphous carbon)and DLC(diamond-like carbon),have attracted considerable attention from both academia and industry,owing to their superior performance,such as chemical inertness,mechanical hardness and electrical conductivity.However,Ta-C films as protective coating of PEMFCs have been rarely reported,due to the difficulty in production for industrial application.In this paper,multi-layer Ta-C composite films were produced by using customized industrial-scale vacuum equipment to address those issues.[Methods]Multiple layered Ta-C coatings were prepared by using PIS624 equipment,which assembled filtered cathodic arc evaporation,ion beam and magnetron sputtering into one equipment,while SS304 and silicon specimens were used as substrate for testing and analysis.Adhesion layer and intermediate layer were deposited by using magnetron sputtering at deposition temperature of 150℃and pressure of 3×10^(−1) Pa,while the sputtering current was set to be 5 A and bias power to be 300 V.The Ta-C layer was coated at arc current of 80-100 A,bias voltage of 1500 V and gas flow of 75 sccm.A scanning electron microscope(CIQTEK SEM3200)was used to characterize surface morphology,coating structure and cross-section profile of the coatings.Raman spectrometer(LabRam HR Evolution,HORIBA JOBIN YVON)was used to identify the bonding valence states.Electrochemical tests were performed by using an electrochemical work station(CHI760,Shanghai Chenhua Instrument Co.,Ltd.),with the traditional three electrode system,where saturated Ag/AgCl and platinum mesh were used as the reference electrode and counter electrode,respectively.All samples were mounted in plastic tube and sealed with epoxy resin,with an exposure area of 2.25 cm^(2),serving as the working electrode.Electrochemical measurements were carried out in simulated PEMFCs cathode environment in 0.5 mol·L^(−1) H_(2)SO_(4)+5 ppm F−solution,at operating temperature of 70℃.As the cathode environment was harsher than the anode environment,all the samples are stabilized at the open-circuit potential(OCP)for approximately 30 min before the EIS measurements.ICR between bipolar plates and GDL was a key parameter affecting performance of the PEMFCs stack.The test sample sandwiched between 2 pieces of carbon paper(simulate gas diffusion layer,GDL)was placed between 2 gold-plated copper electrodes at a compaction pressure of 1.4 MPa,which was considered to be the conventional compaction pressure in the PEMFCs.Under the same conditions,the resistance of a single carbon paper was measured as well.The ICR was calculated according to the formula ICR=1/2(R2−R1)×S,where S was the contact area between GDL and coated stainless steel BPPs.All data of ICR were measured three times for averaging.[Results]The coatings deposited by filtered cathodic arc technology were compact and smooth,which reduced coating porosity and favorable to corrosion resistance.The coating thickness of adhesion and intermediate layers were 180 nm,while the protective Ta-C coating thickness was about 300 nm,forming multiple coating to provide stronger protection for metal bipolar plates.Cr,Ti,Nb and Ta coatings were selected as adhesion layers for comparison.According to electrochemical test,Ta and Nb coatings have higher corrosion resistance.However,Ta and Nb materials would be costly when they are used for mass production.Relatively,Cr and Ti materials were cost effective.Hence,a comprehensive assessment was indispensable to decide the materials to be selected as adhesion layer.Ta-TiN and Ti-TiN combined adhesion and intermediate layer exhibited stronger corrosion resistance,with the corrosion current to be less than 10^(−6) A·cm^(−2).Ta-C protective coating deposited by using filtered cathodic arc technology indicated displayed higher corrosion resistance,with the average corrosion density to be about 1.26×10^(−7) A·cm^(−2).Ta-C coating also shown larger contact angle,with the highest hydrophobicity,which was one of the important advantages for Ta-C,in terms of corrosion resistance.According to Raman spectroscopy,the I(D)/I(G)=549.8/1126.7=0.487,with the estimated fraction of sp^(3) bonding to be in the range of 5154%.The intermediate layer TiN has higher conductivity than the CrN layer.Considering cost,corrosion performance and ICR result,the Ti-TiN layer combination is recommended for industrial scale application.[Conclusions]Multiple layer coating structure of Ta-C film had stronger corrosion resistance;with more than 50%sp^(3) content,while it also had larger water contact angle and higher corrosion resistance than DLC film.The filtered arcing deposition technology was able to make the film to be more consistent and stable than normal arcing technology in terms of the preparation of Ta-C.The coating displayed corrosion density of 1.26×10^(−7) A·cm^(−2) and ICR of less than 5 mΩ·cm^(2),far beyond technical target of 2025 DOE(US Department of Energy).This indicated that the mass-production scale coating technology for PEMFC bipolar plates is highly possible.
基金supported by National Natural Science Foundation of China(Nos.82322015,82171006)Sichuan Province Youth Science and Technology Innovation Team(No.2022JDTD0021)+3 种基金Sichuan Science and Technology Program(No.2022NSFSC0002)West China Hospital of Stomatology Sichuan University(No.RCDWJS2024-3)Sichuan Science and Technology Program(Nos.2023NSFSC1706,2024NSFSC1589)Postdoctoral Science Foundation of China(No.BX20220220)。
文摘Osteogenic ability impairment and myelosuppression are common complications of chemotherapy and many chemotherapeutics can affect the skeletal system.Skeletal system protection is necessary for cancer chemotherapy.In this study,osteogenic growth peptide(OGP)and tetrahedral framework nucleic-acid nanostructures(tFNAs)are combined to form a peptide-DNA complex OGP-tFNAs,which aims to combine the positive biological effect on tissue protection and regeneration.The bone marrow protection and bone formation effect of OGP-tFNAs are investigated in chemotherapy-induced myelosuppressive mice.The results show that OGP-tFNAs could reduce the cell damage degree from 5-fluorouracil(5-FU)in vitro and maintained the osteogenic differentiation potential.Furthermore,OGP-tFNAs accelerate bone defect regeneration in myelosuppressive mice.In conclusion,OGP-tFNAs could protect the osteogenic differentiation potential of bone marrow stromal cells(BMSCs)from 5-FU injury and maintain the bone formation ability of myelosuppressive mice suffering from chemotherapy.
基金supported by National Natural Science Foundation of China(Nos.81874027,82370929,81970916)Sichuan Science and Technology Program(Nos.2019YFQ0003,2022YFS0051,2022NSFSC0002)+3 种基金Sichuan Province Youth Science and Technology Innovation Team(No.2022JDTD0021)Research and Develop Program,West China Hospital of Stomatology Sichuan University(Nos.RD03202302,RCDWJS2024–1)135-project for disciplines of excellenceClinical Research Incubation project of West China Hospital of Sichuan University(No.2021HXFH036)。
文摘Neuropathic pain(NP)is one of the most common pathological pain types and is associated with limited treatment options;moreover,it affects patients’quality of life and causes a heavy social burden.Despite the emphasis on inhibiting neuronal apoptosis to relieve NP,the crucial role of a neuroinflammation is often overlooked.Therefore,refocusing on the regulation of microglia polarization to create a more conducive environment for neuron holds great potential in NP treatment.In recent years,small interfering RNAs(siRNAs)had become an attractive therapeutic option.However,an efficient loading and delivery system for siRNA is still in lack.In our study,a nanostructured tetrahedral framework nucleic acid loaded with the small interfering RNA C–C chemokine receptor 2(T-siCCR2)was successfully designed and synthesized for use in NP rat model in vivo and in a lipopolysaccharide(LPS)-induced inflammatory environment in vitro.This nanoscale complex is endowed with structural stability and satisfactory delivery efficiency while assuring the silencing effect of siRNA-CCR2.In vivo,T-siCCR2 treatment exhibited favorable effects on pain relief and functional improvement in the NP animal model by directly targeting microglia.In vitro,T-siCCR2 counteracts LPS-induced inflammation by inhibiting the differentiation of microglia toward the M1 phenotype,thus playing a neuroprotective role.RNA sequencing was subsequently performed to elucidate the underlying mechanism involved.These results indicate that T-siCCR2 may serve as a potential treatment option for NP in the future.
基金supported by the National Natural Science Foundation of China(No.82101077)Sichuan Science and Technology Program(No.2023NSFSC1516)+2 种基金Postdoctoral Science Foundation of China(Nos.2021M692271,2023T160455)West China School/Hospital of Stomatology Sichuan University,No.RCDWJS2023-5,Fundamental Research Funds for the Central UniversitiesResearch and Develop Program,West China Hospital of Stomatology Sichuan University.
文摘Diabetic kidney disease(DKD)is recognized as a severe complication in the development of diabetes mellitus(DM),posing a significant burden for global health.Major characteristics of DKD kidneys include tubulointerstitial oxidative stress,inflammation,excessive extracellular matrix deposition,and progressing renal fibrosis.However,current treatment options are limited and cannot offer enough efficacy,thus urgently requiring novel therapeutic approaches.Tetrahedral framework nucleic acids(tFNAs)are a novel type of self-assembled DNA nanomaterial with excellent structural stability,biocompatibility,tailorable functionality,and regulatory effects on cellular behaviors.In this study,we established an in vitro high glucose(HG)-induced human renal tubular epithelial cells(HK-2 cells)pro-fibrogenic model and explored the antioxidative,anti-inflammatory,and antifibrotic capacity of tFNAs and the potential molecular mechanisms.tFNAs not only effectively alleviated oxidative stress through reactive oxygen species(ROS)-scavenging and activating the serine and threonine kinase(Akt)/nuclear factor erythroid 2-related factor 2(Nrf2)/heme oxygenase-1(HO-1)signaling pathway but also inhibited the production of proinflammatory factors such as tumor necrosis factor(TNF-α),interleukin-1β(IL-1β),and interleukin-6(IL-6)in diabetic HK-2 cells.Additionally,tFNAs significantly downregulated the expression of Collagen I andα-smooth muscle actin(α-SMA),two representative biomarkers of pro-fibrogenic myofibroblasts in the renal tubular epithelial-mesenchymal transition(EMT).Furthermore,we found that tFNAs exerted this function by inhibiting the Wnt/β-catenin signaling pathway,preventing the occurrence of EMT and fibrosis.The findings of this study demonstrated that tFNAs are naturally endowed with great potential to prevent fibrosis progress in DKD kidneys and can be further combined with emerging pharmacotherapies,providing a secure and efficient drug delivery strategy for future DKD therapy.
基金Project supported by the National Key R&D Program of China (Grant No. 2022YFA1403800)the National Natural Science Foundation of China (Grant Nos. 12250008 and 12188101)+1 种基金the Project for Young Scientists in Basic Research (Grant No. YSBR-059)performed in part at the Aspen Center for Physics, supported by the National Natural Science Foundation of China (Grant No. PHY2210452)。
文摘We theoretically study the effect of a uniform orbital magnetic field on spin waves in a triangular lattice tetrahedral antiferromagnetic insulator without spin–orbit coupling. Through symmetry analysis and microscopic calculation, we show that the optical spin wave mode at the Brillouin zone center can acquire a small orbital magnetic moment, although it exhibits no magnetic moment from the Zeeman coupling. Our results are potentially applicable to intercalated van der Waals materials and twisted double-bilayer graphene.
基金supported by the National Natural Science Foundation of China (Nos. 82101077, 82370929)Sichuan Science and Technology Program (Nos. 2023NSFSC1516, 2023NSFSC1706)+3 种基金Postdoctoral Science Foundation of China (Nos. 2021M692271, 2023T160455, BX20220220, 2022M722251)West China School/Hospital of Stomatology Sichuan University (No. RCDWJS2023–5)Fundamental Research Funds for the Central UniversitiesResearch and Develop Program, West China Hospital of Stomatology Sichuan University
文摘Hyperglycemia resulting from diabetes mellitus(DM)exacerbates osteoporosis and fractures,damaging bone regeneration due to impaired healing capacity.Stem cell therapy offers the potential for bone repair,accelerating the healing of bone defects by introducing stem cells with osteogenic differentiation ability.Dental follicle stem cells(DFSCs)are a newly emerging type of dental stem cells that not only have the potential for multipotent differentiation but also hold easy accessibility and can stand longterm storage.However,DM-associated oxidative stress and inflammation elevate the risk of DFSCs dysfunction and apoptosis,diminishing stem cell therapy efficacy.Recent nanomaterial advances,particularly in DNA nanostructures like tetrahedral framework nucleic acids(tFNAs),have been promising candidates for modulating cellular behaviors.Accumulating experiments have shown that tFNAs’cell proliferation and migration-promoting ability and induce osteogenic differentiation of stem cells.Meanwhile,tFNAs can scavenge reactive oxygen species(ROS)and downregulate the secretion of inflammatory factors by inhibiting various inflammation-related signaling pathways.Here,we applied tFNAs to modify DFSCs and observed enhanced osteogenic differentiation alongside ROS scavenging and anti-inflammatory effects mediated by suppressing the ROS/mitogen-activated protein kinases(MAPKs)/nuclear factor kappa-B(NF-κB)signaling pathway.This intervention reduced stem cell apoptosis,bolstering stem cell therapy efficacy in DM.Our study establishes a simple yet potent tFNAs-DFSCs system,offering potential as a bone repair agent for future DM treatment.
基金Supported by National Natural Science Foundation of China(No.60875046)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT1109)+5 种基金the Key Project of Chinese Ministry of Education(No.209029)the Program for Liaoning Excellent Talents in University(No.LR201003)the Program for Liaoning Science and Technology Research in University(No.LS2010008,2009S008,2009S009, LS2010179)the Program for Liaoning Innovative Research Team in University(Nos.2009T005, LT2010005, LT2011018)Natural Science Foundation of Liaoning Province(201102008)"Liaoning Bai Qian Wan Talents Program(2010921010, 2011921009)"
文摘This paper presents a reconstruction algorithm to build a surface mesh approximating an object from an unorganized point sampling of the boundary object. It combines 3D Delaunay tetrahedralization and mesh-growing method and uses only once Delau- nay triangulation. It begins with 3D Delaunay triangulation of the sampling. Then initialize the surface mesh with seed facets se- lected from Delaunay triangulation. Selection is based on the angle formed by the circumscribing ball of incident tetrahedral. Finally, grow until complete the surface mesh based on some heuristic rules. This paper shows several experimental results that demonstrate this method can handle open and close surfaces and work efficiently on various object topologies except non-manifold surface with self-intersections. It can reproduce even the smallest details of well-sampled surfaces but not work properly in every under-sampled situation that point density is too low.
基金This research is supported by the Dutch Technology Foundation STW,which is part of the Netherlands Organization for Scientific Research(NWO),and which is partly funded by the Ministry of Economic Affairs(project codes:11300 and 11185).
文摘For storing and modeling three-dimensional(3D)topographic objects(e.g.buildings,roads,dykes,and the terrain),tetrahedralizations have been proposed as an alternative to boundary representations.While in theory they have several advantages,current implementations are either not space efficient or do not store topological relationships(which makes spatial analysis and updating slow,or require the use of an expensive 3D spatial index).We discuss in this paper an alternative data structure for storing tetrahedralizations in a database management system(DBMS).It is based on the idea of storing only the vertices and stars of edges;triangles and tetrahedra are represented implicitly.It has been used previously in main memory,but not in a DBMS.We describe how to modify it to obtain an efficient implementation in a DBMS,and we describe how it can be used for modeling 3D topography.As we demonstrate with different real-world examples,the structure is compacter than known alternatives,it permits us to store attributes for any primitives,and has the added benefit of being topological,which permits us to query it efficiently.The structure can be easily implemented in most DBMS(we describe our implementation in PostgreSQL),and we present some of the engineering choices we made for the implementation.
基金supported by the 973 Program of China 2005CB321702China NSF 10531080.
文摘Local mesh refinement is one of the key steps in the implementations of adaptive finite element methods. This paper presents a parallel algorithm for distributed memory parallel computers for adaptive local refinement of tetrahedral meshes using bisection. This algorithm is used in PHG, Parallel Hierarchical Grid Chttp：//lsec. cc. ac. cn/phg/）, a toolbox under active development for parallel adaptive finite element solutions of partial differential equations. The algorithm proposed is characterized by allowing simukaneous refinement of submeshes to arbitrary levels before synchronization between submeshes and without the need of a central coordinator process for managing new vertices. Using the concept of canonical refinement, a simple proof of the independence of the resulting mesh on the mesh partitioning is given, which is useful in better understanding the behaviour of the biseetioning refinement procedure.
基金supported by National Key R&D Program of China (2019YFA0110600)National Natural Science Foundation of China (81970986, 81771125)
文摘Osteoarthritis, a disorder characterized by articular cartilage deterioration, varying degrees of inflammation, and chondrocyte apoptosis, is the most common chronic joint disease. To slow or reverse its progression, inflammation should be inhibited, and chondrocyte proliferation should be promoted. Tetrahedral framework nucleic acids can be internalized by chondrocytes(even inflammatory chondrocytes) and can enhance their proliferation and migration. Wogonin, a naturally occurring flavonoid,suppresses oxidative stress and inhibits inflammation. In this study, tetrahedral framework nucleic acids were successfully selfassembled and used to load wogonin. We confirmed the effective formation of tetrahedral framework nucleic acid/wogonin complexes by dynamic light scattering, zeta potential analysis, transmission electron microscopy, and fluorescence spectrophotometry. Tetrahedral framework nucleic acids, wogonin, and especially tetrahedral framework nucleic acid/wogonin complexes effectively alleviated inflammation in vitro and in vivo and prevented cartilage destruction. In addition, these materials remarkably downregulated the expression of inflammatory mediators and matrix metalloproteinases, upregulated chondrogenic markers, and promoted tissue inhibitor of metalloproteinase 1 and B-cell lymphoma 2 expression. In vivo, after treatment with tetrahedral framework nucleic acid/wogonin complexes, the bone mineral density in regenerated tissues was much higher than that found in the untreated groups. Histologically, the complexes enhanced new tissue regeneration, significantly suppressed chondrocyte apoptosis, and promoted chondrogenic marker expression. They also inhibited cell apoptosis, increased chondrogenic marker expression, and suppressed the expression of inflammatory mediators in osteoarthritis. Therefore, we believe that tetrahedral framework nucleic acid/wogonin complexes can be used as an injectable form of therapy for osteoarthritis.
基金Project supported by the National Natural Science Foundation of China (No.69833010)
文摘The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN application is automatic creating data structure. Although a raster algorithm has been introduced by some authors, the problems in accuracy, memory requirement, speed and integrity are still existent. In this paper, the raster algorithm is completed and a vector algorithm is presented after a 3-D data model and structure of TEN have been introducted. Finally, experiment, conclusion and future work are discussed.
基金supported by the National Natural Science Foundation of China(Nos.21875044,21673048)Key Basic Research Program of Science and Technology Commission of Shanghai Municipality(No.17JC1400100)+2 种基金the support by the state key laboratory of Transducer Technology of China(No.SKT1904)Program of Shanghai Academic Research Leader(No.19XD1420300)Research Supporting Project(No.RSP-2019/155)by King Saud University。
文摘Incorporation of heteroatoms into the framewo rk of zeolites has become a significant strategy to improve their performance in catalysis and adsorption,because the obtained heteroatom zeolites exhibit quite different properties from the conventional aluminosilicate zeolites in aspects of surface acidity,pore structures,particle size and so on.In this review,the progress on the heteroatom zeolites including their synthesis and application is highlighted.First,the recent advance on the design and synthesis of different heteroatom zeolites is summarized.Special emphasis is placed on the introduction and comparison of three typical methods,including the direct synthesis,post synthesis and improved direct synthesis,for the traditional heteroatom zeolites(such as TS-1,Sn-MFI,Sn-β) and newly-reported heteroatom zeolites(such as W-MFI,Mo-MFI).According to their intrinsic characteristics,the application of heteroatom zeolites in diverse fields,such as production of fine chemicals,air pollution control and biomass conversion is then discussed.Finally,the challenges and perspective on the future development of heteroatom zeolites in low-cost preparation and practical application are proposed.
基金funded by The National Science Fund for Distinguished Young Scholars of China(No.52025014)National Science and Technology Major Project(No.2017-VII-0012-0108)+2 种基金K.C.Wong Education Foundation(No.GJTD-2019-13)CAS Interdisciplinary Innovation Team(No.292020000008)Ningbo Science and Technology Innovation Project(No.2018B10012)。
文摘In this work,the high temperature friction mechanism of the tetrahedral amorphous carbon(ta-C)film was elucidated.The multilayer ta-C film with alternating hard and soft sub-layers exhibited a low friction coefficient of 0.14 at 400℃ before a sudden failure occurred at 4600 cycles.The wear failure was attributed to the gradual consumption of the ta-C film at the contact region.The design of a hard or soft top layer effectively regulated the high temperature friction properties of the multilayer ta-C.The addition of a hard top layer contributed to a low friction coefficient(0.11)and a minor wear rate(4.0×10^(-7)mm^(3)/(N m)),while a soft top layer deteriorated the lubrication effect.It was proposed that the passivation of dangling bonds at the sliding interface dominated the low-friction mechanism of the ta-C film at high temperature,while the friction induced graphitization and the formation of sp^(2)-rich carbonaceous transfer layer triggered C-C inter-film bonding,resulting in serious adhesion force and lubrication failure.Moreover,the multilayer ta-C film with hard top layer obtained excellent friction performance within 500℃,while the high temperature induced oxidation and volatilization of carbon atoms led to the wear failure at 600℃.
基金supported by National Key R&D Program of China(2019YFA0110600)National Natural Science Foundation of China(82101077,81970916)+3 种基金Sichuan Province Youth Science and Technology Innovation Team(2022JDTD0021)Sichuan University Postdoctoral Interdisciplinary Innovation Fundthe Fundamental Research Funds for the Central Universities,Postdoctoral Science Foundation of China(Grant 2021M692271)West China School/Hospital of Stomatology Sichuan University(No.RCDWJS2022-14 and RCDWJS2021-20)。
文摘With the emergence of DNA nanotechnology in the 1980s, self-assembled DNA nanostructures have attracted considerable attention worldwide due to their inherent biocompatibility, unsurpassed programmability, and versatile functions. Especially promising nanostructures are tetrahedral framework nucleic acids(t FNAs), first proposed by Turberfield with the use of a one-step annealing approach. Benefiting from their various merits, such as simple synthesis, high reproducibility, structural stability, cellular internalization, tissue permeability, and editable functionality, t FNAs have been widely applied in the biomedical field as threedimensional DNA nanomaterials. Surprisingly, t FNAs exhibit positive effects on cellular biological behaviors and tissue regeneration,which may be used to treat inflammatory and degenerative diseases. According to their intended application and carrying capacity,t FNAs could carry functional nucleic acids or therapeutic molecules through extended sequences, sticky-end hybridization,intercalation, and encapsulation based on the Watson and Crick principle. Additionally, dynamic t FNAs also have potential applications in controlled and targeted therapies. This review summarized the latest progress in pure/modified/dynamic t FNAs and demonstrated their regenerative medicine applications. These applications include promoting the regeneration of the bone,cartilage, nerve, skin, vasculature, or muscle and treating diseases such as bone defects, neurological disorders, joint-related inflammatory diseases, periodontitis, and immune diseases.
基金National Key R&D Program of China(2019YFA0110600)National Natural Science Foundation of China(81970916,81671031)the LU JIAXI International team program supported by the K.C.Wong Education Foundation and CAS and the Youth Innovation Promotion Association of CAS(Grant No.2016236).
文摘Obesity-induced insulin resistance is the hallmark of metabolic syndrome,and chronic,low-grade tissue inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells.Current therapeutic approaches lack efficacy and immunomodulatory capacity.Thus,a new therapeutic approach is needed to prevent chronic inflammation and alleviate insulin resistance.Here,we synthesized a tetrahedral framework nucleic acid(tFNA)nanoparticle that carried resveratrol(RSV)to inhibit tissue inflammation and improve insulin sensitivity in obese mice.The prepared nanoparticles,namely tFNAs-RSV,possessed the characteristics of simple synthesis,stable properties,good water solubility,and superior biocompatibility.The tFNA-based delivery ameliorated the lability of RSV and enhanced its therapeutic efficacy.In high-fat diet(HFD)-fed mice,the administration of tFNAs-RSV ameliorated insulin resistance by alleviating inflammation status.tFNAs-RSV could reverse M1 phenotype macrophages in tissues to M2 phenotype macrophages.As for adaptive immunity,the prepared nanoparticles could repress the activation of Th1 and Th17 and promote Th2 and Treg,leading to the alleviation of insulin resistance.Furthermore,this study is the first to demonstrate that tFNAs,a nucleic acid material,possess immunomodulatory capacity.Collectively,our findings demonstrate that tFNAs-RSV alleviate insulin resistance and ameliorate inflammation in HFD mice,suggesting that nucleic acid materials or nucleic acid-based delivery systems may be a potential agent for the treatment of insulin resistance and obesity-related metabolic diseases.
基金supported by the National Natural Science Foundation of China (Grant No.30370106)
文摘Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera （G. Don） Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi （Sweet） Pojarkova range from 37.67 μm to 61.06μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding ＆ Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.
基金the National Council of Science and Technology, Mexico CONACyT for the support provided for this research, through the Basic Science project CB-2011/ 169786
文摘In turbulence modeling, the RNG and Realizable models have important improvements in the turbulent production and dissipation terms in comparison to the Standard. The selection of the appropriate turbulence model has an impact on the convergence and solution in STRs, and they are used in mixing, multiphase modeling or as starting solution of transient models as DES and LES. Although there are several studies with the pitched blade turbine(PBT) impeller, most of them used the Standard model as representative of all k–ε models, using structured hexahedral grids composed of low number of cells, and in some cases under axial symmetry assumptions.Accordingly, in this work the assessment of the Standard, RNG and Realizable models to describe the turbulent flow field of this impeller, using the Multiple Reference Frame(MRF) and Sliding Mesh(SM) approaches with tetrahedral domains in dense grids, is presented. This kind of cell elements is especially suitable to reproduce complex geometries. Flow velocities and turbulent parameters were verified experimentally by PIV and torque measurements. The three models were capable of predicting fairly the pumping number, the power number based on torque, and velocities. Although the RNG improved the predictions of the turbulent kinetic energy and dissipation rate, the Realizable model presented better performance for both approaches. All models failed in the prediction of the total dissipation rate, and a dependence of its value on the number of cells for the MRF was found.
文摘The microstructure and properties of tetrahedral amorphous carbon (ta-C) films deposited by the filtered cathodic vacuum arc technology has been investigated by visible Raman spectroscopy, AFM and Nano-indentor. The Raman spectra have been fitted with a single skewed Lorentzian lineshape described by BWF function defining coupling coefficient, which characterizes the degree of asymmetry and is correlated with the sp3 content. When the substrate bias is -80 V, the sp3 content is the most and simultaneously the coupling coefficient is the least, following with the minimum root mean square surface roughness (Rq=0.23 nm) and the highest hardness (51.49 GPa), Young′s modulus (512.39 GPa), and critical scratching load (11.72 mN). As the substrate bias is increased or decreased, the sp3 content and other properties lower correspondingly.
基金supported by National Key R&D Program of China (No. 2019YFA0110600)National Natural Science Foundation of China (No. 81970916)+2 种基金Sichuan Province Youth Science and Technology Innovation Team (No. 2022JDTD0021)Research Funding from West China School/Hospital of Stomatology Sichuan University (No. RCDWJS2021-20)China Postdoctoral Science Foundation (No. 2022TQ0381)。
文摘Synthetic antigen-encoding mRNA plays an increasingly significant role in tumor vaccine technology owing to its antigen-specific immune-activation. However, its immune efficacy is challenged by inferior delivery efficiency and demand for suitable adjuvants. Here, we develop a novel mRNA nanovaccine based on a multifunctional nanocapsule, which is a dual-adjuvant formulation composed of cytosine-phosphateguanine motifs loaded tetrahedral framework nucleic acid(CpG-tFNA) and an immunopeptide murine β-defensin 2(mDF2β). This m RNA nanovaccine successfully achieves intracellular delivery, antigen expression and presentation of dendritic cells, and proliferation of antigen-specific T cells. In a tumor prophylactic vaccination model, it exerts an excellent inhibitory effect on lymphoma occurrence through cellular immunity. This mRNA nanovaccine has promising prophylactic applications in tumors and many other diseases.
