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Developing long-lifetime bulk-form ceramic-based materials with high irradiation resistance is crucial for advanced nuclear systems. Here, we incorporated carbon nanotubes (CNTs) into yttria-stabilized zirconia (YSZ) and magnesia (MgO) nanocrystals to fabricate bulk YSZ-MgO-CNT nanocomposites with abundant ternary nanostructures by spark plasma sintering. To understand the role of tailored ternary nanostructure on irradiation, we investigated the microstructure and mechanical properties evolutions of the YSZ-MgO-CNT nanocomposites irradiated by multi-energy He+ ions at high temperature to different fluences. Compared with the single-phase YSZ and ultrafine-grained YSZ-MgO composites, the YSZ-MgO-CNT nanocomposites possessed higher ability to manage irradiation-induced He bubbles/defects via the defect-interface interactions of proposed “loading-unloading” and “loading-transporting-unloading” mechanisms for controlling the dynamical behaviors of He atoms/defects in the CNT-doped ternary nanostructures, thereby presenting more stable microstructure and better performance in resisting irradiation hardening. This work provides insight into the design of advanced inert matrix nuclear fuel and new nuclear waste management materials.

Tungsten (W) as plasma facing material (PFM) needs to face an unprecedented harsh environment in the fusion reactor, which puts forward high requirements for its radiation tolerance. Among the many challenges, the rapid accumulation of helium (He) atoms to form numerous bubbles or even “fuzzy” nanostructure leads to swelling and embrittlement of W matrix and seriously shorten its service life, which is one of the most serious problems faced by PFM-W at present. In this review, we summarize the recent works on the nanochannel W films with high surface-to-volume ratio deposited by magnetron sputtering, and the behaviors of He in the nanochannel W films at different fusion-related irradiation environment. Experimental and simulation results showed that the nanochannel W films have better radiation tolerance performance in managing He behaviors than that of commercial bulk W.

The polycrystalline fluorapatite Ca10(PO4)6F2 ceramic synthesized by a standard solid-state sintering method was pre-irradiated with 80 keV He+ ions to a fluence of 5 × 1016 ions/cm2 at room temperature. After that, an in-situ annealing experiment was performed inside a transmission electron microscope to monitor the evolution of helium bubbles during heating to 723 and 823 K. Initially, no helium bubble formation was observed in the damage layers of the pre-irradiated samples. However, as the temperature increased, helium bubbles first became visible and then began coarsening, ultimately reaching an asymptotic radius during annealing. The migration and coalescence of helium bubbles in the fluorapatite matrix was complete at a temperature of 823 K, and its likely mechanism involved the existence of two different types of coalescing bubbles.

Surfaces with gradient topography are important in various fields but are difficult to fabricate. Herein, we report a facile and robust way to fabricate a surface with gradient topography of porous structure, in one direction, based on the breath figure (BF) method for the first time. The influencing factors including relative humidity (RH), sample immersion time, and solvent composition, affecting the speed, time, and model of the droplet growth, respectively, were investigated to control gradient BF pores with different ranges of pore sizes. Applying appropriate parameters, gradient BF pores with a diameter difference over 400% were prepared on one sample. The mechanism of gradient duration of solvent evaporation at different regions of a sample for fabricating gradient pores was proposed and experimentally verified with recording optical and thermographic changes of the sample in the BF procedure. This new method provides a novel site for gradient topography fabrication.

It has long been hypothesized that an increase in the extracellular matrix (ECM) stiffness mechanoactivates malignant phenotypes of breast tumor cells by regulating an array of processes underlying cancer biology. Although the contribution of substrate stiffening to drive malignant phenotype traits and other biological functions of a tumor is increasingly understood, the functional role of substrate softening on breast cancer cellular responses has rarely been investigated. Herein, we employed matrix metalloproteinase (MMP)-sensitive film to perform assays to explore the consequences of lowering stiffness on the biological behaviors of breast cancer cell MDA-MB-231. We demonstrated that cells underwent dramatic changes in migration, cellular conjunction, and expression of malignance-associated proteins and genes when the substrate stiffness decreased. Based on RNA sequencing and analysis, we found that hub genes including TP53, CCND1, MYC, CTNNB1, and YAP were validated to play central parts in regulating stiffness-dependent cellular manner change. Moreover, through visualization of differentially expressed genes (DEGs), cells on dynamically softened substrate appeared less influenced by transfer to tissue culture polystyrene (TCPS). These results suggest substrates with decreasing stiffness could normalize breast tumor malignant phenotype and help cells store the mechanical memory of the consequential weaker malignance.

In recent years, femtosecond laser direct writing technology has made great progress in integrated quantum photonic circuits due to its advantages of applicability to an extensive range of materials and true 3-D ability. However, a waveguide prepared via a femtosecond laser shows a non-circular cross section and high birefringence, which seriously restricts the development of polarization encoded quantum photonic integrated chips towards greater integration and higher functions. Here, we propose an amplitude-phase double shaping method to reduce waveguide birefringence, which involves using a cylindrical lens and slits. A waveguide prepared using this method shows a circularity cross-section that reaches up to 97.6% and a birefringence that is as low as 1.49 × 10−6. Based on such an ultralow birefringence waveguide, a polarization independent Hong-Ou-Mandel quantum interferometer was fabricated. Interference visibilities for identical photon pairs in different polarization states were found to be more than 95% with a standard deviation of 0.6%. The ultra-low birefringence single-mode waveguide and the polarization-independent interferometer realized using this approach will play an important role in large-scale polarization encoding integrated quantum photonic chips.

Room-temperature ferromagnetism in WO3 films was enhanced by 130 keV Ar+ ion irradiation. The X-ray diffraction (XRD) and Raman measurements not only confirmed the monoclinic phase of the irradiated WO3 films, but also showed that oxygen vacancy (VO) defects were formed. The analysis of photoluminescence spectra strongly reconfirmed the presence of oxygen vacancy. X-ray photoelectron spectroscopy (XPS) measurements revealed that the contents of VO and induced W5+ ions increase with increasing irradiation fluence and rich W5+-VO defect complexes in the irradiated WO3 films were formed. Further, the magnetic measurements exhibited a 2-fold enhancement in the saturation magnetization at the largest fluence of 3 × 1016 ions/cm2. At lower irradiation fluence, a bound magnetic polaron model was proposed to reveal the ferromagnetic exchange coupling resulting from overlapping of VO+ and VO++ defect states, and 5d1 states of W5+. At high irradiation fluence, the carrier concentration reaches 1.02 × 1020/cm3 and carrier-mediated exchange interactions result in the film's ferromagnetism.

In this paper, we report a new type of MoS2-based grating sensor for in-plane biaxial strain gauges with a precision limit of ~ 1‰. The MoS2grating is numerically simulated with different biaxial strains up to 5%. Our first-principles calculations reveal that the strain sensitivity of the MoS2reflectance spectrum can be considered an additional strain sensor integrated with the grating structure, enabling the mapping of in-plane biaxial strains. Our experimental studies on a prototype MoS2-grating sensor further confirm that a strain component perpendicular to the grating period can cause intensity peak shifts in the grating’s first-order diffraction patterns. This work opens a new path towards the sensing of in-plane biaxial strain within a single-grating device. Our new approach is applicable for other materials that have predictable reflectance response under biaxial strains and the capacity to form a two-dimensional single-crystal layer.

Surface-enhanced Raman spectroscopy (SERS) of rhodamine 6G (R6G) was investigated using a hybrid nanostructure of double-aligned Ag nanowires (AgNWs) on a bilayer triangular MoS2 flake under excita...

Medical coatings are now playing key roles in the practical use of biomedical devices. By fabricating coatings, the biocompatibility of the devices would be significantly improved, and their biofunctions would be multiplied. Biomedical devices can thus satisfy the clinical requirements to a better extent with the help of coatings. Polymers and inorganic materials are the most used components in the medical coatings, while they both show limitations. By combining polymers and inorganic materials, researchers can fabricate coatings with the advantages of both components. The inorganic-polymer composite coatings would be much more qualified to enhance biocompatibility and bioactivity of the medical devices, showing great potentials in biomedical applications. In this review, we summarize the inorganic-polymer composite biomedical coatings. We introduce metal and metal oxide-based, carbon-based, ceramic-based, and silica-based composite coatings. We illustrate that what materials were used, how they were designed and fabricated into coatings, and what goals the composite coatings realized.

Coating modification such as drug-eluting coating is one of the most important approaches for the functionalization of biomedical devices. However, the throughputs are limited in conventional coating methods and the concept of miniaturization is rarely fulfilled. A droplet microarray (DMA), as a unique high-throughput platform, can avoid cross-contamination and reduce the consumption of materials which is inherently suitable for coating research yet is difficult to apply with coating materials via traditional methods. Here, we bring up a facile method based on ultrasonic spray deposition to integrate coating materials into a DMA. Several common polymer materials were selected to fabricate a DMA, and the obtained DMA showed the ability to anchor water droplets and form specific patterns. Coating arrays with a typical sandwich structure were also prepared for the high-throughput screening of drug-eluting coatings to demonstrate the potential of the platform in coating research. This developed method is efficient and compatible and enriches the choices of materials that can be applied in DMAs.

Summary Developing outstanding radiation-resistant materials with excellent thermal and mechanical properties and self-healing ability remains a great challenge for advanced nuclear energy systems. Here, we incorporate three-dimensional (3D) carbon nanotube (CNT) networks into iron nanocrystals (Fe NCs) to obtain functional bulk Fe-CNT nanocomposites, exhibiting much higher thermal conductivity and mechanical properties than the Fe NCs without sacrificing strength. Irradiations by energetic helium (He) and krypton ions show that 3D CNT networks act as gigantic-capacity “nano-dustbins” to collect and store He atoms and defects via a “loading-transporting-unloading” mechanism in the grain boundary-CNT (GB-CNT) configuration, thus greatly enhancing their radiation tolerance compared with the Fe NC counterparts. The energetic landscape of interactions of He/defects with the GBs and the Fe-CNT interfaces in the nanocomposites are revealed by first-principles calculations. This work offers a promising strategy for material design of high-performance structural materials for future advanced nuclear reactors.

Magnetic impurities in metallic superconductors are important for both fundamental and applied sciences. In this study, we focused on dilute Mn-doped aluminum (AlMn) films, which are common superconducting materials used to make transition edge sensors and other superconducting devices. We developed a multi-energy ion-implantation technique to make AlMn films. Compared with frequently used sputtering techniques, ion-implantation provides more precise control of the Mn doping concentration in the AlMn films. It enables us to fabricate reliably AlMn films with a different superconducting transition temperature (Tc) that can match a variety of application needs. We also found that the superconducting transition temperature drops with increasing film thickness for samples with the same nominal concentration of Mn dopants. The dependence of Tc on the film thickness is attributed to the increasing implantation energy. By quantitatively analyzing the curves of Tc versus the Mn doping concentration, we propose that Mn dopants act as magnetic impurities and suppression of superconductivity is counteracted by the antiferromagnetic Ruderman–Kittel–Kasuya–Yosida interaction among Mn dopants, which is influenced by the defects induced in the ion-implantation process.

Si-based materials have been extensively studied because of their high theoretical capacity, low working potential, and abundant reserves, but serious initial irreversible capacity loss and poor cyclic performance resulting from large volume change of Si during lithiation and delithiation processes restrict their widespread application. Herein, we report the preparation of multi-shell coated Si (DS-Si) nanocomposites by in-situ electroless deposition method using Si granules as the active materials and copper sulfate as Cu sources. The ratio of Si and Cu was readily tuned by varying the concentration of copper sulfate. The multi-shell (Cu@CuxSi/SiO2) coating on Si surface promotes the formation of robust and dense SEI films and the transportation of electron. Thus, the obtained DS-Si composites exhibit an initial coulombic efficiency of 86.2%, a capacity of 1636 mAh g−1 after 100 discharge–charge cycles at 840 mA g−1, and an average charge capacity of 1493 mAh g−1 at 4200 mA g−1. This study provides a low-cost and large-scale approach to the preparation of nanostructured Si-metal composites anodes with good electrochemical performance for lithium ion batteries.

This work demonstrated a significant hydrogen isotopes permeation resistance in nitride nano-multilayer coatings. Dense and homogeneous CrN/AlTiN nano-multilayer coatings with different period-thicknesses were fabricated as hydrogen isotopes permeation barriers (HIPB) to highlight the effect of interface on hydrogen isotopes permeation resistance. Deuterium permeation measurement found that the nano-multilayer coatings had much higher permeation reduction factors (PRF) than the corresponding monolayer coatings, and more importantly there was an interface-number-dependent deuterium permeation resistance where the nano-multilayer coating containing more interfaces had higher PRF. Interfaces in the nano-multilayer coatings play a key role in the significant improved deuterium permeation resistance which was explained from three aspects. Ceramic nano-multilayer coatings offer a promising alternative for the design and preparation of HIPB in the hydrogen related fields.

Plasmonic nanocavities comprised of metal film-coupled nanoparticles have emerged as a versatile nanophotonic platform benefiting from their ultrasmall mode volume and large Purcell factors. In the weak-coupling regime, the particle-film gap thickness affects the photoluminescence (PL) of quantum emitters sandwiched therein. Here, we investigated the Purcell effect-enhanced PL of monolayer MoS2 inserted in the gap of a gold nanoparticle (AuNP)–alumina (Al2O3)–gold film (Au Film) structure. Under confocal illumination by a 532 nm CW laser, we observed a 7-fold PL peak intensity enhancement for the cavity-sandwiched MoS2 at an optimal Al2O3 thickness of 5 nm, corresponding to a local PL enhancement of ∼350 by normalizing the actual illumination area to the cavity’s effective near-field enhancement area. Full-wave simulations reveal a counterintuitive fact that radiation enhancement comes from the non-central area of the cavity rather than the cavity center. By scanning an electric dipole across the nanocavity, we obtained an average radiation enhancement factor of about 65 for an Al2O3 spacer thickness of 4 nm, agreeing well with the experimental thickness and indicating further PL enhancement optimization. Our results indicate the importance of configuration optimization, emitter location and excitation condition when using such plasmonic nanocavities to modulate the radiation properties of quantum emitters.

The concept of high-throughput screening sheds new light on fabrication and analysis of materials. Herein, a combinatorial surface-modified platform with biochemical gradients was developed through thiol-ene "click" chemistry by adjusting the intensity of ultraviolet (UV) irradiation. Contact angle, X-ray photoelectron spectroscopy, and ellipsometry measurement results demonstrated that the sulfhydryl molecules including polyethylene glycol and RGD (arginine-glycine-aspartic acid) and REDV (arginine-glutamic acid-aspartic acid-valine) peptides can be directly attached onto alkene-modified substrates, in which the graft density can be well controlled by the intensity of UV irradiation. The multistep attachment of different molecules onto substrates is archived via the multistep UV-initiated thiol-ene "click" reaction. The high-throughput arrays with the gradient density of single ligand and the orthogonal gradient density of two ligands were rapidly fabricated via the one-step UV gradient irradiation and the two-step orthogonal UV gradient-initiated thiol-ene "click" reaction. Endothelial cells (ECs) and smooth muscle cells (SMCs) were cocultured on the array with the orthogonal gradient density of RGD and REDV to screen the peptide combination with high EC selectivity, which is essential for in situ endothelialization during stent implant. From 64, 8 × 8, combinations investigated, a special combinatorial surface representing the really high competitiveness of ECs over SMCs was screened. This platform puts forward a facile, high-throughput method to study the combinatorial variation of biochemical signals to cell behavior.

Hematite is a prospective semiconductor in photoelectrochemical (PEC) water oxidation field due to its suitable bandgap for the solar spectrum absorption. Nevertheless, the low transfer and separation efficiency of the charge carriers are restricted by its diffusion length of hole which is 2–4 nm and further reduce the PEC performance. Here, we report an innovative method, by introducing nanocavities into the α-Fe2O3 nanorod arrays photoanodes through helium ions implantation, to improve the charge carriers' transfer and separation efficiency and further to enhance water oxidation performance. The result indicates that, the photocurrent density of nanocavities embedded α-Fe2O3 photoanode (S2-A sample) reaches 1.270 mA/cm2 at 1.6 V vs. RHE which is 1-fold higher than that of the pristine α-Fe2O3 (0.688 mA/cm2) and the photocurrent density of S2-A sample reaches 0.652 mA/cm2 at 1.23 V vs. RHE. In this work, the ion implantation combined with post annealing method is found to be a valid method to improve the photoelectrochemical performance, and it also can be further used to modify the other semiconductor photoelectrodes materials.

Ho3+ and Yb3+ codoped bismuth titanate (BTO) composite powders with infrared to visible upconversion luminescence (UCL) function were prepared by SGC method. The effects of Ho3+ and Yb3+ doping content on the structure and property were investigated for BTO: xHo, 0.2 Yb (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) and BTO: 0.02Ho, yYb (y = 0.1, 0.2, 0.3, 0.5, 0.7, 0.9) samples. All the samples include three bismuth titanate phases (Bi4Ti3O12, Bi2Ti2O7, and Bi20TiO32), and the phase proportion can be tuned by changing Ho3+ and Yb3+ doping content. These powders are well crystalized with honeycomb-like microscopic structure, and with good absorption for 233 nm, 310 nm and 975 nm wavelength. The band gap can be tuned from 3.53 eV to 4.03 eV when increasing Yb3+ content from y = 0 to y = 0.9. A strong 530–580 nm green emission band and a relative weak 630–690 nm red one corresponding to Ho3+: 5S2 → 5I8 and 5F5 → 5I8 transitions appear in the UCL spectra for all the BTO: Ho, Yb samples when pumped at 980 nm. The emission intensities can well be tuned with various Ho3+ and Yb3+ content. The optimal UCL was obtained in BTO: 0.02Ho, 0.5 Yb for all the prepared samples. The energy transfer mechanism is analyzed by building a two-photon energy transfer model, which is proved by the relationship between emission intensities and pumping power measurement. The concentration quenching of Ho3+ is caused by cross relaxation of CR1 and CR2 (Ho: 5F4, 5S2 + 5I8 → 5I4 + 5I7) and by CR3 (Ho: 5F4, 5S2 + Yb: 2F7/2 → Ho: 5I6 + Yb: 2F5/2) for Yb3+ quenching. The mean luminescence lifetime (τm) from Ho: 5S2 decreases monotonously with the increase of Ho3+ and Yb3+ content.

Persistent luminescence has shown great potential in anticounterfeiting technology benefiting from the feature of free background. However, current anticounterfeiting technology faces the challenge...

Metallic multilayered nanofilms have been extensively studied owing to their unique physical properties and applications. However, studies on the thermal conductivity and electrical resistivity of metallic multilayered nanofilms, as their important physical properties, are seldom reported. In this work, Cu/W multilayered nanofilms with periodic thickness varying from 6 to 150 nm were deposited by magnetron sputtering. The resistivities of the Cu/W multilayered nanofilms increase with the decrease of periodic thickness, especially when the periodic thickness is smaller than 37 nm. The resistivities of the multilayered nanofilms fit well with the Fuchs-Sondheimer and Mayadas-Shatzkes (FS-MS) model, which considers both interface scattering and grain boundary scattering. The thermal conductivities of the Cu/W multilayered nanofilms were measured by the three-omega (3ω) method, which decrease with a decrease of periodic thickness initially and increase at the smallest periodic thickness of 6 nm. The Boltzmann transport equation (BTE)-based model was used, to explain the periodic thickness-dependent thermal conductivity of metallic multilayered nanofilms by considering the contributions from both phonon and electron heat transport processes, where the calculated thermal conductivities agree well with the measured ones. The electrical resistivity and thermal conductivity strongly depend on the microstructures of the multilayered nanofilms.

Broadband absorption in the mid-infrared region is of significance for wide applications, such as photo/thermal detection, infrared stealth, and thermal imaging. Recently, metal-based plasmonic absorbers have been developed in the mid-infrared region. However, the fabrication cost, thickness, and bandwidth of these absorbers applied in aerospace still need to be improved. In this study, we propose and experimentally demonstrate a large-area, rather thin, metal-free absorber with broadband mid-infrared absorption based on a low-cost self-assembly process. The metal-free absorber is fabricated by spraying carbon black nanoparticles onto 5 μm-thick transferrable anodic aluminum oxide (AAO) templates on nanoporous Si graded-index films, which are fabricated by ion irradiation. Experimental results show that the average absorbance can reach 97.5% in the range of 2.5-15.3 μm. Full-wave numerical simulations show that the electromagnetic fields are greatly enhanced into pores, as these random carbon black particles serve as scatter centers and couple light into 5 μm-thick AAO templates, enhancing the interaction of light with carbon black significantly, and reveal that the high-performance broadband absorption is attributed to the light-trapping effect. The significant light absorption combined with a low-cost, high-production self-assembly technique suggests that the absorber can be used in the fields of optoelectronics and integrated photonics.

Si-based materials with high theoretical storage capacity and low working potential are one of the ideal anode materials for next-generation lithium-ion batteries, but their large volume change and low conductivity obstruct the commercial application. This article presents a brief overview of insights into charge–discharge mechanism and the main challenges of Si-based anodes in the past few years and outlines typical solving strategies, new mechanism, advanced characterization technology, and future directions.

Porous surfaces have attracted tremendous interest for customized incorporation of functional agents on biomedical devices. However, the versatile preparation of porous structures on complicated devices remains challenging. Herein, we proposed a simple and robust method to fabricate "spongy skin" on diversified polymeric substrates based on non-solvent-induced phase separation (NIPS). Through the swelling and the subsequent phase separation process, interconnected porous structures were directly formed onto the polymeric substrates. The thickness and pore size could be regulated in the ranges of 5-200 and 0.3-0.75 μm, respectively. The fast capillary action of the porous structure enabled controllable loading and sustained release of ofloxacin and bovine albumin at a high loading dosage of 79.9 and 24.1 μg/cm2, respectively. We verified that this method was applicable to diversified materials including polymethyl methacrylate, polystyrene, thermoplastic polyurethane, polylactide acid, and poly(lactic-co-glycolic acid) and can be realized onto TCPS cell culture plates. This NIPS-based method is promising to generate porous surfaces on medical devices for incorporating therapeutic agents.

We report on fabrication of tapered circular depressed-cladding waveguides in Nd:YAG crystal by femtosecond laser direct writing (FsLDW). Based on the fabricated waveguides, for the first time to the best of our knowledge, efficient Q-switched mode-locked (QML) lasers are realized by employing silver nanoparticles (NPs) embedded in fused silica as saturable absorber (SA) element. Laser pulses as short as 25 ps with a repetition rate of 7.7 GHz are generated at a wavelength of 1064 nm. We systematically explore the influence of incident-output facet and the reduction factors on guiding properties and laser performance by conducting a comparative study of different tapers, and it has been found that the waveguides with tapered structures can suppress multi-mode guiding while ensure fundamental-mode output for waveguide lasers. Our work paves a new way toward developing three-dimensional (3D) waveguide for applications in on-chip ultrafast laser sources., National Natural Science Foundation of China (12074223, 1210040430); Taishan Scholar Foundation of Shandong Province; Qilu Young Scholar Program of Shandong University; China Postdoctoral Science Foundation (2020M682155); Consejería de Educación, Junta de Castilla y León (SA287P18, SA136P20); Ministerio de Economía y Competitividad (FIS2017-87970R).

Developing surfaces that realize lubrication and durable wear resistance under high pressure has great implications in areas ranging from electromechanical systems to advanced biomedical devices but has proven challenging. Inspired by the zonal and transitional structure of articular cartilage, we fabricate a hydrogel-elastomer hybrid surface, where the hydrogel interpenetrates into the polymer elastomer substrate as a transitional and bonding zone, that exhibits a low coefficient of friction and wear resistance under a high load. First, we entrap benzophenone within the surface of polymer substrates such as polydimethylsiloxane, polyvinylchloride, and polyurethane. The hybrid surface is then achieved through initiating polymerization of the acrylamide monomer on the polymer surface upon ultraviolet irradiation. We observe an interpenetration area of the hydrogel and the polymer substrate. The hybrid surface shows a low coefficient of friction (∼0.05) under a very high load (over 100 atm contact pressure). It conserves the lubrication property over 100,000 cycles under a 10.9 MPa pressure and shows slight wear. This work brings a new perspective on designing surfaces with a lubrication property and wear resistance, showing broad applications.

Developing high-performance tungsten plasma-facing materials for fusion reactors is an urgent task. In this paper, novel nanochannel structural W films prepared by magnetron sputtering deposition were irradiated using a high-power pulsed electron beam or ion beam to study their edge-localized modes, such as transient thermal shock resistance. Under electron beam irradiation, a 1 μm thick nanochannel W film with 150 watt power showed a higher absorbed power density related cracking threshold (0.28–0.43 GW/m2) than the commercial bulk W (0.16–0.28 GW/m2) at room temperature. With ion beam irradiation with an energy density of 1 J/cm2 for different pulses, the bulk W displayed many large cracks with the increase of pulse number, while only micro-crack networks with a width of tens of nanometers were found in the nanochannel W film. For the mechanism of the high resistance of nanochannel W films to transient thermal shock, a residual stress analysis was made by Grazing-incidence X-ray diffraction (GIXRD), and the results showed that the irradiated nanochannel W films had a much lower stress than that of the irradiated bulk W, which indicates that the nanochannel structure can release more stress, due to its special nanochannel structure and ability for the annihilation of irradiation induced defects.

Boosting second-order optical nonlinear frequency conversion over subwavelength thickness has long been pursued through optical resonance in micro- and nanophotonics. However, the availability of thin film materials with high second-order nonlinearity is limited to III-V semiconductors, which have low transparency in the visible. Here, we experimentally demonstrated strongly enhanced second harmonic generation in one-dimensional heterostructure cavities on thin film lithium niobate. A guided-mode resonance resonator and distributed Bragg reflectors are combined for both efficient coupling and electromagnetic field localization. Over 1200 times second harmonic generation enhancement is experimentally realized compared with flat thin film lithium niobate through optimizing the trade-off between quality factor and mode volume, leading to a record high normalized conversion efficiency of $2.03\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{cm}}^{2}/\mathrm{GW}$ under $1.92\text{ }\text{ }\mathrm{MW}/{\mathrm{cm}}^{2}$ pump intensity. Our approach could inspire the miniaturization and integration of compact resonant nonlinear photonic devices on thin film lithium niobate.

A series of novel Li+ doped Bi3.46Ho0.04Yb0.5Ti3O12 (BHYTO: xLi, 0 ≤ x ≤ 0.15) upconversion phosphors were prepared through a sol-gel-sintering method. There exist three emission bands centered at 545 nm, 658 nm, and 756 nm in the upconversion emission spectra at 980 nm excitation, corresponding to energy transitions of 5F4/5S2&nbsp, →&nbsp, 5I8, 5F5&nbsp, 5I8 and 5F4/5S2&nbsp, 5I7 of Ho3+, and the upconversion emission intensity of BHYTO: 0.05Li is about 2.2 times stronger than that of BHYTO samples. The luminescent lifetime of the strongest emission (545 nm) is in the range of 45.25 to 65.99 μs for the different BHYTO: xLi phosphors. The energy transfers during the upconversion pumping process from Yb3+ to Ho3+ are mainly responsible for all the emissions, each belonging to a double-photon process. Li+ mainly entered into the interspace sites or occupied Bi3+ sites in Bi4Ti3O12 host during the fabrication process according to its dosage, and the possibility is very low for Li+ to take part in the energy transfer process directly due to its lack of matching levels with 4f of Ho3+ and Yb3+. However, Li+ doping can not only increase the size of crystal grains to improve crystallinity through XRD analysis, but also reduced oxygen vacancies to decrease the number of quenching centers through XPS analysis. The improved crystallinity and reduced quenching centers are proposed to be the main causes for the enhanced upconversion luminescence of the Li+ doped BHYTO phosphor.

Renowned for its high theoretical specific energy, lithium-sulfur (Li–S) batteries still suffer from the shuttle effect of polysulfides, the insulating nature of sulfur and severe volumetric variations, especially for cathodes with high sulfur contents. Herein, S microsphere encapsulated within a thickness-tunable multilayered thin V/V2O5 nanoshell (S@V/V2O5) was explored as a high-sulfur-content cathode (up to 93 wt%) for Li–S batteries. With a polar V2O5 moiety the nanoshell could physically block and chemically adsorb polysulfides, while the metallic V could assure efficient electron transfer; this multilayered and porous nanoshell could also buffer the volumetric variations of the sulfur core and facilitate Li+ transportation. Such S@V/V2O5 electrode with a 87 wt% sulfur content delivers high specific capacity (1403 mAh g−1) and remarkable areal initial capacity (4.4 mAh cm−2) at 0.2 C, excellent cycling stability (819 mAh g−1 at 0.5 C after 300 cycles), superior high-rate capacity (804 mAh g−1 at 4 C), low self-discharge (759 mAh g−1 after resting 50 days) and a high coulombic efficiency above 90% in a LiNO3-free electrolyte. A current collector-free S@V/V2O5 cathode with sulfur content of 93 wt% is also achieved, which yields stable discharge capacity of 1000 mAh g−1 at 0.2 C after 100 cycles.

Embedded copper nanoparticles (Cu NPs) with spherical geometry are synthesized by Cu+ ion implantation in lithium tantalate (LiTaO3) crystal. Because of the localized surface plasmon resonance (LSP...

Black phosphorus (BP) nanostructures with unique layer-dependent properties have been extensively applied in the fields of electronic devices, energy conversion and storage, and nanomedicine. As a narrow band gap semiconductor, they are expected to show strong second near-infrared (NIR-II) fluorescence. However, there is no report on the NIR-II fluorescence of free-standing BP nanostructures, which have great potential in the NIR-II fluorescence bioimaging because of their excellent biocompatibility and biodegradability. Here, for the first time, we report that the BP nanoparticles modified with cholesterol exhibit strong NIR-II fluorescence and can be encapsulated with the PEGylated lipid to form BP@lipid-PEG nanospheres for in vitro and in vivo NIR-II imaging. The resultant BP@lipid-PEG nanospheres exhibit broad emissions from 900 to 1650 nm under excitation by an 808 nm laser and have 8% quantum yield of that of standard dye IR-26. We also show that the NIR-II fluorescence image acquired with emission beyond 1400 nm has the sharpest contrast and can be used to in situ measure the diameter of blood vessels. In addition to NIR-II fluorescence imaging, we also show the potential of BP@lipid-PEG nanospheres in photoacoustic (PA) imaging. Both the long-wavelength NIR-II fluorescence imaging and PA imaging reveal that the as-fabricated BP@lipid-PEG nanospheres can be gradually metabolized by the liver in 48 h, thus making them promising for bioapplications.

Cellular behavior is crucially dependent on the biophysical and biochemical properties of the extracellular matrix (ECM), in which the properties of biochemistry, topography, and mechanics are critically important and dominantly studied. Since its introduction by Decher and Lvov in the early 1990s, layer-by-layer (LbL) assembly technology has received considerable interest for constructing polymeric thin films in both academic and industrial studies. The technology has been especially important in applications involving biomedical materials, tissue engineering, and regenerative medicine. In recent years, because of outstanding flexibility and multipotency, polymeric LbL thin films have been extensively studied to create a biomimetic cellular microenvironment with one or more biophysical and biochemical properties. The field has moved from simple mimicking to active control of various cellular behaviors. This review first introduces the basic background of the natural cellular microenvironment, the LbL assembly, and progress in polymeric LbL thin films. Next, biomimetic films constructed using the LbL technique are introduced. The biochemical components, topographical features, and mechanical properties of the films are detailed. Furthermore, progress in thin LbL films for controlling cell behavior, such as cell adhesion, stem cell differentiation, and cell-cell interactions, are highlighted. Finally, the review closes with a summary and a brief outlook of the opportunities and challenges associated with polymeric LbL thin films for advancing promising future developments.

Breast cancer remains to show high mortality and poor prognosis in women despite of significant progress in recent diagnosis and treatment. Herein, we report the rational design of a highly efficient ultrasmall nanotheranostic agent with excellent photodynamic therapy (PDT) performance to against breast cancer and its metastasis by eliciting antitumor immunity. The ultrasmall nanoagent (3.1 ± 0.4 nm) was fabricated from polyethylene glycol modified Cu2- xSe nanoparticles, β-cyclodextrin, and chlorin e6 under ambient conditions. The resultant nanoplatform (CS-CD-Ce6 NPs) can be passively accumulated into the tumor to exhibit dramatic antitumor efficacy through the excellent PDT effect under near-infrared irradiation. The excellent PDT performance of this nanoplatform is owing to its role as a Fenton-like Haber-Weiss catalyst for the efficient degradation of H2O2 within the tumor to release hydroxyl radicals (·OH) and very toxic singlet oxygen (1O2) under irradiation. The generated vast amounts of reactive oxygen species not only killed primary tumor cells but also elicited immunogenic cell death (ICD) to release damage-associated molecular patterns (DAMPs) and induced proinflammatory M1-macrophages polarization. Thereby, antitumor immune responses against the metastasis of breast cancer were robustly evoked. Our work demonstrates that ultrasmall Cu2- xSe nanoparticle-based nanoplatform offers a promising way to prevent cancer metastasis via immunogenic effects through its excellent PDT performance.

An olivine-structured solid solution, LiFe0.4Mn0.4Co0.2PO4/C nanocomposite, was synthesized as cathode materials for Li-ion batteries by the coprecipitation-and-milling method using stearic acid as the carbon source. Thus-formed LiFe0.4Mn0.4Co0.2PO4/C solid solution was well confirmed and characterized by various techniques such as SEM, TEM and XRD. The LiFe0.4Mn0.4Co0.2PO4/C-based cathode delivered an initial discharge capacity of 163.3 mAh g−1 at 0.1 C, together with a capacity retention rate of 86.6% after 50 cycles in the potential range of 2.5–5 V. Even at 1 C, a discharge capacity of 104.7 mAh g−1 was maintained after 100 cycles. The good electrochemical performance of the LiFe0.4Mn0.4Co0.2PO4/C could be attributed to the homogeneous mixing of Fe, Mn and Co elements in relevant precursor solid solution Fe0.4Mn0.4Co0.2C2O4·2H2O. Its characteristic CV profiles reveal three pairs of anodic/cathode peaks which could be assigned to the redox reactions of Co3+/Co2+, Mn3+/Mn2+ and Fe3+/Fe2+ with potential plateaus at about 4.7 V, 4.1 V and 3.5 V in the charge/discharge curves, respectively. Our study demonstrates that the LiFe0.4Mn0.4Co0.2PO4/C is a promising cathode material of Li-ion battery and the coprecipitation-and-milling method represents a workable strategy towards the synthesis of high-performance phosphate-type composite cathode.

Monolithic waveguide laser devices are required to achieve on-chip lasing. In this work, a new design of a monolithic device with embedded Ag nanoparticles (NPs) plus the Nd:YAG ridge waveguide has been proposed and implemented. By using Ag+ ion implantation, the embedded Ag NPs are synthesized on the near-surface region of the Nd:YAG crystal, resulting in the significant enhancement of the optical nonlinearity of Nd:YAG and offering saturable absorption properties of the crystal at a wide wavelength band. The subsequent processing of the O5+ ion implantation and diamond saw dicing of crystal finally leads to the fabrication of monolithic waveguide with embedded Ag NPs. Under an optical pump, the Q-switched mode-locked waveguide lasers operating at 1 μm is realized with the pulse duration of 29.5 ps and fundamental repetition rate of 10.53 GHz, owing to the modulation of Ag NPs through evanescent field interaction with waveguide modes. This work introduces a new approach in the application of monolithic ultrafast laser devices by using embedded metallic NPs.

Patterned slippery surfaces based on the technique of slippery liquid-infused porous surface (SLIPS) have broad technological applications in biofouling, liquid handling, biomolecule collection, and droplet microarrays. However, methods to generate patterned SLIPS with flexibility and practical potential remain a technical roadblock. Here, we report an approach for generating patterned SLIPS, and by utilizing which, as a proof-of-technique application, the droplet microarrays have been presented. Our approach is based on a photocross-linkable polyelectrolyte poly(ethyleneimine)/azide-poly(acrylic acid) (PEI/PAA-N3) film, whose surface structures can be dynamically controlled. We have prepared the surface-patterned PEI/PAA-N3 film containing microstructured and flat regions. We then demonstrate that, because of much higher lubricant retaining capability of the microstructured regions, a patterned SLIPS can be simply generated through infusing the lubricant onto the surface and applying a shear spinning pro...

Resonant frequency and impedance matching have great significance for the vibration performance and online monitoring of the rotary ultrasonic machining. Network compensation is a typical solution to match the resonant frequency and the impedance between the rotary ultrasonic holder (RUH) and the ultrasonic transducer. However, the traditional bilateral compensation method could adversely affect the rotary dynamic balance of the RUH. Currently, the existing unilateral compensation methods can only realize the resonant frequency matching. A novel unilateral compensation method that satisfies both the resonant frequency and the impedance matching is proposed. First, the impedance model of the RUH vibrating system is established according to its equivalent circuit. It is found that, without any compensation methods, the resonant frequency and the impedance between the RUH and the transducer have deviated. Second, the primary-series and primary-parallel compensation topologies are applied to the RUH system, and the expressions of compensation capacitance value, voltage gain, power transfer efficiency, and output active power are derived. The deviations of the resonant frequency and the impedance are eliminated with primary-series compensation topology; and as a result, the voltage gain is increased from 0.267 to 0.90, the output active power is 11.3 times than that without compensation. Third, the state-space model of primary-series topology is constructed. Finally, the above theoretical results are verified by the experimental results.

Nanofilms are of great interest as a kind of separation membranes for seawater desalination and wastewater treatment. Their fabrication, however, always needs a time-consuming process and shows low atom economy. Herein, we report pyrogallol/polyethyleneimine (PG/PEI) nanofilms spontaneously formed at the gas/liquid interface within ten minutes and composited on microporous substrates. Both the film thickness and the surface charge are facilely adjusted by the reaction time and the mass ratio of PG/PEI in aqueous solution. The solution is repeatedly used to fabricate the nanofilm composite membranes and thus this method is with high atom economy of raw materials. The as-prepared nanofilm composite membranes can be directly applied in aqueous nanofiltration, showing a relatively high water permeation flux (17.5 L m−2 h−1 bar−1) and salt rejection (>94% for MgCl2) during a long-term operation. The nanofilms are also demonstrated potentials in organic solvent nanofiltration after moderate cross-linking by glutaraldehyde.

In the present study, the microstructures and properties of DSS 2205 solid wire MIG welded samples prepared in different shielding gases (pure Ar gas, 98%Ar + 2%O2 and 98%Ar + 2%N2) were investigated for improving the weldability of DSS 2205 welded joint. The work was conducted by mechanical property tests (hardness and tensile test) and corrosion resistance property tests (immersion and electrochemical tests). The results show that adding 2%O2 into pure Ar gas as the shielding gas decreases crystal defects (faults) and improves the mechanical properties and corrosion resistance of the welded joints. Phase equilibrium and microstructural homogeneity in welded seam (WS) and heat-affected zone (HAZ) can be adjusted and the strength and corrosion resistance of welded joints increased obviously by adding 2%N2 to pure Ar gas as the shielding gas. Compared with DSS 2205 solid wire MIG welding in 98%Ar + 2%O2 mixed atmosphere, the strength and corrosion resistance of welded joints are improved more obviously in 98%Ar + 2%N2 mixed atmosphere.

Periodic porous structures have been introduced into functional films to meet the requirements of various applications. Though many approaches have been developed to generate desired structures in polymeric films, few of them can effectively and dynamically achieve periodic porous structures. Here, a facile way is proposed to introduce periodic stratified porous structures into polyelectrolyte films. A photo‐crosslinkable polyelectrolyte film of poly(ethylenimine) (PEI) and photoreactive poly(acrylic acid) derivative (PAA‐N3) is prepared by layer‐by‐layer (LbL) self‐assembly. Stratified crosslinking of the PEI/PAA‐N3 film is generated basing on standing‐wave optics. The periodic stratified porous structure is constructed by forming pores in noncrosslinked regions in the film. Thanks to the dynamic mobility of polyelectrolytes, this structural controlment can be repeated several times. The size of pores corresponding to the layer spacing of the film contributes to the structural colors. Furthermore, structural color patterns are fabricated in the film by selective photo‐crosslinking using photomasks. Although the large‐scale structural controlment in thick (micron‐scale and above) films needs to be explored further, this work highlights the periodic structural controlment in polymeric films and thus presents an approach for application potentials in sensor, detection, and ink‐free printing., The periodic stratified porous structures are generated in polyelectrolyte film through periodic crosslinking based on the standing‐wave optics. The film at solid‐state and porous‐state is switched reversibly. Subsequently, the film displays different structural color.

BACKGROUND: The challenges of clinical translation of optical imaging, including the limited availability of clinically used imaging probes and the restricted penetration depth of light propagation in tissues can be avoided using Cerenkov luminescence endoscopy (CLE). However, the clinical applications of CLE are limited due to the low signal level of Cerenkov luminescence and the large transmission loss caused by the endoscope, which results in a relatively low detection sensitivity of current CLE. The aim of this study was to enhance the detection sensitivity of the CLE system and thus improve the system for clinical application in the detection of gastrointestinal diseases. METHODS: Four optical fiber endoscopes were customized with different system parameters, including monofilament (MF) diameter of imaging fiber bundles, fiber material, probe coating, etc. The endoscopes were connected to the detector via a specifically designed straight connection device to form the CLE system. The β-2-[(18)F]-Fluoro-2-deoxy-D-glucose ((18)F-FDG) solution and the radionuclide of Gallium-68 ((68)Ga) were used to evaluate the performance of the CLE system. The images of the (18)F-FDG solution acquired by the CLE were used to optimize imaging parameters of the system. By using the endoscope with optimized parameters, including the MF diameter of imaging fiber bundles, fiber materials, etc., the resolution and sensitivity of the assembled CLE system were measured by imaging the radionuclide of (68)Ga. RESULTS: The results of (18)F-FDG experiments showed that larger MF diameter led to higher collection efficiency. The fiber material and probe coating with high transmission ratios in the range of 400–900 nm also increased signal collection and transmission efficiency. The results of (68)Ga evaluations showed that a minimum radioactive activity of radionuclides as low as 0.03 µCi was detected in vitro within 5 minutes, while that of 0.68 µCi can be detected within 1 minute. In vivo experiments also demonstrated that the developed CLE system achieved a high sensitivity at a submicrocurie level; that is, 0.44 µCi within 5 minutes, and 0.83 µCi within 1 minute. The weaker in vivo sensitivity was due to the attenuation of the signal by the mouse tissue skin and the autofluorescence interference produced by biological tissues. CONCLUSIONS: By optimizing the structural parameters of fiber endoscope and imaging parameters for data acquisition, we developed a CLE system with a sensitivity at submicrocurie level. These results support the possibility that this technology can clinically detect early tumors within 1 minute.

To meet the diversity needs of diagnosis, treatment or prevention of diseases, different pharmaceutical dosage forms are designed and manufactured. The main role of each dosage form is drug carrier. However, changing forms might have some other different effects in clinical usages. For example, the capsule and tablets are absorbed by the intestine and stomach respectively, solutions and patches can act directly on the surface of skin etc. The quantity and quality analysis of the main drug in different form is a key issue in quality control. Therefore, it is a meaningful research of developing a facility method to detect the drug in different dosage forms. The traditional drug detection methods principally analyze and evaluate the performance through chemical reactions, photo-electricity or electrophoresis. However, these methods will cause damage to the samples. Owing to the non-invasive, non-destructive and label-free characteristics, Raman spectroscopy (RS) technique plays an important role in different fields. The current RS setup uses Gaussian beam as the excitation light, which can provide higher signal-to-noise in the thin or transparent sample. However, the Gaussian beam dispersed rapidly in the scattering medium, it is not conducive to in vivo or deep imaging. The Bessel beam having long focusing characteristics and self-reconstructing properties may provide solution to this problem. We here presented a new scheme for RS, which used a Bessel beam as the excitation light. The feasibility and effectiveness of the proposed scheme for detecting the drug in different pharmaceutical dosage forms were verified by series experiments.

It is very difficult to prepare red/near-infrared emission carbon dots (CDs) for bio-imaging applications which are needed because of their deep tissue penetration, minimal auto-fluorescence, and low emission light damage to bio-tissues. Near-infrared emitting CDs (NIR-CDs) were synthesized from sulfonated tetraphenylporphyrin using a solvothermal method. They have excitation-independent properties with a maximum emission at 692 nm. Studies showed that this unique near-infrared emission mainly originated from the aggregated molecular states of the CDs. The NIR-CDs showed good water solubility, exceptional biocompatibility, low toxicity, and superior cellular labelling ability. This work could significantly advance the structural design and preparation of NIR-CDs and corresponding bio-imaging applications.

Achievement of an endothelial cell (EC) monolayer (re-endothelialization) on the vascular implant surface with competent and functioning features is critical for long-term safety after implantation. Oriented EC monolayer is beneficial to improve endothelial function such as enhanced athero-resistant property. However, the information about antithrombotic property of oriented EC monolayer is limited. Here, we used the microgrooved polydimethylsiloxane substrates to guide EC orientation and obtain oriented EC monolayer. The effects of anisotropic topography on EC behaviors and antithrombotic function of the EC monolayer were then evaluated. Our data demonstrated that ECs responded to grooves in a size-dependent way as shown in oriented cell cytoskeleton and nuclei, enhanced directed migration, and overall velocity. Furthermore, compared to the EC monolayer on the flat surface, the oriented EC monolayer formed on the grooved substrates exhibited improved antithrombotic capability as indicated by higher expression of functional related genes, production of prostacyclin and tissue plasminogen activator, and prolonged activated coagulation time. The improvement of antithrombotic function was especially notable on the smaller-size groove. These findings reveal the responses of ECs to varisized topography and antithrombotic function of the oriented EC monolayer, providing insights into optimal design of vascular implants.

Nonlinear interactions between light and matter give rise to a wide range of applications for both fundamental and applied research. Herein, near‐infrared switching of the optical response based on embedded Ag nanoparticles and laser‐written optical waveguides within yttrium vanadate (YVO4) crystal matrix is demonstrated. Using broadband transient absorption spectroscopy with a combination of femtosecond Z‐scan spectroscopy, the plasmon‐enhanced features of the third‐order optical nonlinearity in Ag:YVO4 nanocomposite at the near‐infrared band are elucidated. Meanwhile, an optical‐lattice‐like microscale waveguide is fabricated with well‐preserved photoluminescence properties by femtosecond laser writing. Taking advantage of the ultrafast on–off switching behavior of Ag:YVO4 saturable absorber, a Q‐switched pulsed laser operation in the waveguide platform, delivering 1 μm light pulses with high peak power of 298 mW, is demonstrated. This work indicates a possible path for the development of chip‐scale ultrafast photonic devices.