摘要：RECENTLY, frequency selective excitation was extensively studied and applied successfullyto various types of nuclear magnetic resonance (NMR) experiments. Solvent suppression,double resonance, multiple quantum coherence, as well as multi-dimensional NMR are all re-lated to selective excitation. Probably, its most important application is in NMR ***, selective excitation unit (SEU) has become an important accessory in modernNMR spectrometer.

摘要：The combined use of guided tissue/bone regeneration(GTR/GBR)membranes and bone filling grafts represents a classical therapy for guiding the regeneration and functional reconstruction of oral soft and hard ***,due to its displacement and poor mechanical support,bone meal is not suitable for implantation in the case of insufficient cortical bone support and large dimensional *** combination of GTR/GBR membrane with a three-dimensional(3D)porous scaffold may offer a resolution for the repair and functional reconstruction of large soft and hard tissue *** this study,a novel integrated gradient biodegradable porous scaffold was prepared by bonding a poly(lactic-co-glycolic acid)(PLGA)/fish collagen(FC)electrospun membrane(PFC)to a 3D-printed PLGA/nano-hydroxyapatite(HA)(PHA)*** consistency of the composition(PLGA)ensured strong interfacial bonding between the upper fibrous membrane and the lower 3D *** vitro cell experiments showed that the PFC membrane(upper layer)effectively prevented the unwanted migration of L929 *** in vivo investigations with an oral soft and hard tissue defect model in beagles revealed that the integrated scaffold effectively guided the regeneration of defective oral *** results suggest that the designed integrated scaffold has great potential for guiding the regeneration and reconstruction of large oral soft and hard tissues.

摘要：Carbon dots(CDs)have opened up a new field of carbon nanomaterials and successively attracted increasing attention since their discovery in *** to their ultrasmall size,tunable surface functional groups,excellent dispersibility,attractive stability,low toxicity,environmental friendliness,facile synthesis and low-cost precursors,CDs have been developed as green and promising frictionreducing and anti-wear materials in lubrication science,applied to energy conservation and extension of mechanical service life in recent ***,there are few reviews focusing on the application of CDs in the important field of *** this review,we comprehensively summarize the development of CDs in lubrication for the first ***,three strategies for structural engineering design of CDs to improve their tribological characteristics are fully analyzed,in terms of size and shape control,surface modification and heteroatom ***,the advance in lubrication application of CDs,including CDs as additives for lubricants,greases,gel and magnetorheological fluids as well as CDs as lubricating coatings,is systematically ***,the lubricating mechanisms of CDs as additives are introduced in ***,the remaining major challenges and opportunities for CDs in lubrication field are discussed and outlined.

摘要：The RF coupler is a key component for an accelerating structure which is the most important component for a linac. In order to feed microwave power into the accelerating cavities effectively, the coupler has to be well matched with the feeding waveguide. In this paper, an electron linac coupler was designed, constructed and tested. A numerical simulation method based on the Kyhl＇s method was employed to search for the optimal dimensions of the coupler. The frequency and the coupling coefficient as a function of the coupler dimensions were also calculated. The results fitted the Kyhl＇s method simulation results well and gave tolerances of the coupler. The coupler was brazed to the accelerating cavities and it was cold-tested and hot-tested. The experimental results were consistent with the numerical simulation results.

摘要：Aiming to design stable nanocrystalline(NC)materials,so far,it has been proposed to construct nanostructure stability maps in terms of thermodynamic parameters,while kinetic stabilization has seldom been considered,despite the synergy of thermodynamics and ***,the thermodynamically stabilized NC materials may be easily subjected to grain growth at high temperatures due to the weakly kinetic *** from the thermo-kinetic synergy,a stabilization criterion is proposed as a function of intrinsic solute parameters(*** activation energy for bulk diffusion and the segregation enthalpy),intrinsic solvent parameters(*** intrinsic activation energy for GB migration and the GB energy)and processing parameters(*** grain size,the temperature and the solute concentration).Using first-principles calculations for a series of combinations between fifty-one substitutional alloying atoms as solute atoms and Fe atom as fixed solvent atom,it is shown that the thermal stability neither simply increases with increasing the segregation enthalpy as expected by thermodynamic stabilization,nor monotonically increases with increasing the activation energy for bulk diffusion as described by kinetic *** combination of thermodynamic and kinetic contributions,the current stabilization criterion evaluates quantitatively the thermal stability,thus permitting convenient comparisons among NC materials involved by various combinations of the solute atoms,the solvent atoms,or the processing *** of this thermo-kinetic stabilization criterion has been tested by current experiment results of Fe-Y alloy and previously published data of Fe-Ni,Fe-Cr,Fe-Zr and Fe-Ag alloys,etc.,which opens a new window for designing NC materials with sufficiently high thermal stability and sufficiently small grain size.

摘要：Drug administration customized to individual cells could intrinsically address cancer heterogeneity and provide a safe and effective method for delivering personalized treatment. To accomplish this, we developed a smart nanodrug delivery system characterized by cancer cell-targeted drug delivery and intracellular biomarker-responsive drug activation. This system was composed of a long-nicked DNA duplex formed by tandem hybridization of two extended antisense oligonucleotides whose ends were separately blocked with a cancer cell-specific aptamer, AS1411,and a replaceable anti-biomarker probe(ABP). We demonstrated that this DNA nanodrug was directed to cancer cells with the guidance power of AS 1411 and then activated by the presence of a given intracellular biomarker. By using such a belt-and-braces strategy, this DNA nanodrug system could safely and efficiently accelerate apoptosis of target cancer cells. Moreover, since the expression level of biomarkers tends to indicate the specific physiological state of individual cells, biomarker-responsive activation of the nanodrug is expected to enable customized drug administration at the cellular level.

摘要：At present,the clinical reconstruction of the auricle usually adopts the strategy of taking autologous costal *** method has great trauma to patients,poor plasticity and inaccurate ***-dimensional(3D)printing technology has made a great breakthrough in the clinical application of orthopedic *** study explored the combination of 3D printing and tissue engineering to precisely reconstruct the ***,a polylactic acid(PLA)polymer scaffold with a precisely customized patient appearance was fabricated,and then auricle cartilage fragments were loaded into the 3D-printed porous PLA scaffold to promote auricle *** vitro,gelatin methacrylamide(GelMA)hydrogels loaded with different sizes of rabbit ear cartilage fragments were studied to assess the regenerative activity of various autologous cartilage *** vivo,rat ear cartilage fragments were placed in an accurately designed porous PLA polymer ear scaffold to promote auricle *** results indicated that the chondrocytes in the cartilage fragments could maintain the morphological phenotype in *** three months of implantation observation,it was conducive to promoting the subsequent regeneration of cartilage in *** autologous cartilage fragments combined with 3D printing technology show promising potential in auricle reconstruction.

摘要：Cell-derived microvesicles(MVs) are secreted from almost all kinds of mammalian cells into the extracellular space, and play crucial roles in intercellular communication and transporting biomolecules between cells. However, there is a great challenge for visualizing and monitoring of MVs’ bio-behaviors due to the limitations of existing labeling methods. Herein, we report the first paradigm of designer cell-self-implemented labeling of MVs secreted from living mammalian MCF-7 cells in situ using the intracellular-synthesized fluorescent quantum dots(QDs) during the formation of MVs. By elaborately coupling intracellular biochemical reactions and metabolism pathways, the MCF-7 cells can be illuminated brightly by intracellular-biosynthesized fluorescent CdSe QDs. Simultaneously, intracellular-synthesized QDs can be in situ encapsulated by the secreted MVs budding from the plasma membrane of the fluorescing cells to label the MVs with an efficiency of up to 89.9%. The whole labeling process skillfully combines designer precise cell-tuned intricate synthesis of CdSe QDs with mild in-situ labeling via cell-selfimplementation just after feeding the cell with suitable chemicals, which is structure-or function-nondestructive and much more straightforward and milder than those by chemical conjugation or indirect encapsulation with conventional fluorogenic labels.

摘要：Nanozymes,the functional nanomaterials with enzyme-like activities,have been widely explored for both in vitro and in vivo applications(Wei and Wang,2013;Wu et al.,2019;Huang et al.,2019;Liang and Yan,2019).Particularly,by modulating the levels of reactive oxygen species(ROS)in vivo,numerous therapeutic nanozymes have been developed to treat diseases,ranging from cancer to neurodegenerative diseases(Fan et al.,2018;Kwon et al.,2018).

摘要：Impedance matching is important for achieving high-efficiency microwave absorbers. The high conductivity of dielectric loss materials such as pure metals and carbon nanomaterials generally results in poor absorption owing to the low impedance matching between the absorbers and air. Carbon nanostructures are very promising candidates for high-efficiency absorption because of their attractive features including low density, high surface area, and good stability. Herein, a new strategy is proposed to improve the impedance matching of dielectric loss materials using electrospun carbon nanofibers as an example. The carbon nanofibers are coated with specifically designed gradient multilayer nanofilms with gradually increasing electroconductibility synthesized by doping ZnO with different A1203 content （AZO） by atomic layer deposition. The gradient nanofilms are composed of five layers of dielectric films, namely, pure A1203, AZO （5：1, the pulse cycle ratio of ZnO to A1203）, pure ZnO, AZO （10：1）, and AZO （20：1）. The versatile gradient films serve as intermediate layers to tune the impedance matching between air and the carbon nanofiber surfaces. Therefore, the carbon nanofibers coated with gradient films of rationally selected thicknesses exhibit remarkably enhanced microwave absorption performance, and the optimal reflection loss reaches -58.5 dB at 16.2 GHz with a thickness of only 1.8 mm. This work can help further understand the contribution of impedance matching to microwave absorption. Our strategy is general and can be applied to improve the absorption properties of other dielectric loss materials and even for applications in other fields.