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Cartilage-targeting delivery of therapeutic agents is still an effective strategy for osteoarthritis (OA) therapy. Recently, scavenging for reactive oxygen species (ROS) and activating autophagy have been increasingly reported to treat OA effectively. In this study, we designed, for the first time, a dual-drug delivery system based on metal organic framework (MOF)-decorated mesoporous polydopamine (MPDA) which composed of rapamycin (Rap) loaded into the mesopores and bilirubin (Br) loaded onto the shell of MOF. The collagen II-targeting peptide (WYRGRL) was then conjugated on the surface of above nanocarrier to develop a cartilage-targeting dual-drug delivery nanoplatform (RB@MPMW). Our results indicated the sequential release of two agents from RB@MPMW could be achieved via near-infrared (NIR) laser irritation. Briefly, the rapid release of Br from the MOF shell exhibited excellent ROS scavenging ability and anti-apoptosis effects, however responsively reduced autophagy activity, to a certain extent. Meanwhile, following the NIR irradiation, Rap was rapidly released from MPDA core and further enhanced autophagy activation and chondrocyte protection. RB@MPMW continuously phosphorylated AMPK and further rescued mitochondrial energy metabolism of chondrocytes following IL-1β stimulation via activating SIRT1-PGC-1α signaling pathway. Additionally, the cartilage-targeting property of peptide-modified nanocarrier could be monitored via Magnetic Resonance (MR) and IVIS imaging. More significantly, RB@MPMW effectively delayed cartilage degeneration in ACLT rat model. Overall, our findings indicated that the as-prepared dual-drug delivery nanoplatform exerted potent anti-inflammation and anti-apoptotic effects, rescued energy metabolism of chondrocytes in vitro and prevented cartilage degeneration in vivo, which thereby showed positive performance for OA therapy., Graphical abstract The mechanism of dual-drug delivery nanoplatform with cartilage-targeting effect and NIR laser response for OA therapy.Image 1, Highlights • Collagen type II-targeting peptide and positive surface potential endow RB@MPMW with a fine cartilage affinity ability. • RB@MPMW possess superb biological functions of scavenging free radicals and autophagy induction. • RB@MPMW effectively promotes chondrocyte mitochondrial energy metabolism in the inflammatory microenvironment. • RB@MPMW has a good MR imaging ability, which could monitor its therapeutic effects in vivo.

Wavy-shaped metallic materials play a significant role in various applications. The current synthesis strategy for such materials is limited to top-down thin metal film etching. Note that top-down etching is inevitable to process more surface dangling bonds than their bottom-up analogues and results in poor chemical stability. However, up to now, no bottom-up method has been presented to produce wavy-shaped metallic materials. Here, taking Cu as a model material, a bottom-up two-stage tunneling-dominated electrodeposition strategy is reported to produce ultralong Cu wavy microstructures (WMSs) on a lithographically patterned and native oxide layer-passivated Si electrode, where direct electron transfer is impeded. Scanning electron microscopy and field-emission scanning electron microscopy results demonstrate the large-scale production of Cu WMSs consisting of interconnected octahedral and cuboctahedral nanoparticles. The I–V curve suggests good electrical performance of the as-deposited Cu WMSs. Together...

Osteoarthritis (OA) is a common degenerative disease characterized by the progressive destruction both articular cartilage and the subchondral bone. The agents that can effectively suppress chondrocyte degradation and subchondral bone loss are crucial for the prevention and treatment of OA. Oxymatrine (OMT) is a natural compound with anti‐inflammatory and antitumour properties. We found that OMT exhibited a strong inhibitory effect on LPS‐induced chondrocyte inflammation and catabolism. To further support our results, fresh human cartilage explants were treated with LPS to establish an ex vivo degradation model, and the results revealed that OMT inhibited the catabolic events of LPS‐stimulated human cartilage and substantially attenuated the degradation of articular cartilage ex vivo. As subchondral bone remodelling is involved in OA progression, and osteoclasts are a unique cell type in bone resorption, we investigated the effects of OMT on osteoclastogenesis, and the results demonstrated that OMT suppresses RANKL‐induced osteoclastogenesis by suppressing the RANKL‐induced NFATc1 and c‐fos signalling pathway in vitro. Further, we found that the anti‐inflammatory and anti‐osteoclastic effects of oxymatrine are mediated via the inhibition of the NF‐κB and MAPK pathways. In animal studies, OMT suppressed the ACLT‐induced cartilage degradation, and TUNEL assays further confirmed the protective effect of OMT on chondrocyte apoptosis. MicroCT analysis revealed that OMT had an attenuating effect on ACLT‐induced subchondral bone loss in vivo. Taken together, these results show that OMT interferes with the vicious cycle associated with OA and may be a potential therapeutic agent for abnormal subchondral bone loss and cartilage degradation in osteoarthritis.

Gallium nitride (GaN) nanowires and nanotubes possess extraordinary device ability of converting wasted energy into harvestable electricity in terms of their piezoelectricity and pyroelectricity. From the perspective of atomic cohesive energy, we present a model to clarify the physical origin of the size- and shape-dependency of the piezoelectric and pyroelectric properties for intrinsic GaN nanowires and nanotubes. It is shown that both the piezopotential and the pyropotential increase with the inverse of GaN nanocrystal size or with the shape factor. The influence of size and shape becomes more significant for nanotubes with smaller size or wall thick-to-size ratio and may enhance both potentials by up to dozens of times or even more. Such size and shape effects originate from the synergetic effects of nanoscale dielectricity, piezoelectricity and thermoelasticity where the piezoelectricity plays a more important role than the other two factors. Moreover, high piezopotential and pyropotential in GaN nanotubes render them appealing in the design of novel nanogenerators in comparison with the most commonly used nanowires.

In this work, two-dimensional few-layer palladium ditelluride (PdTe2) nanosheets are produced by the simple and effective ultrasonic liquid exfoliation method and used as novel saturable absorber in an Yb-doped mode-locked fiber laser. The results show that the prepared flexible PdTe2/PVA composite film has a modulation of 3.7% and a saturation intensity of 77.6 MW/cm2. The obtained Yb-doped mode-locked fiber laser based on the film shows a pulse width of 887.2 ps with a repetition and central wavelength of 8.921 MHz and 1069 nm, respectively. So far, there has been few reports on PdTe2 as saturable absorbers to realize mode-locked fiber lasers. The results suggest that two-dimensional PdTe2 has great potential applications in nonlinear optics and ultrafast photonics.

We explore a first-principles study of the structural, electronic, magnetic, and optoelectronic properties of two-dimensional (2D) gallium nitride (GaN) adsorbed by the groups IIIA-VIIA atoms. Our calculations reveal that the chemisorption occurs for all selected adatoms and the adsorption energy of C is the highest because of its special adsorption configuration. The electronic structure studies indicate that the adatoms introduce magnetic feature with spin-polarized properties except for the group VIA atoms. Moreover, a semiconducting state presents in the groups IIIA, IVA and VIA atoms adsorbed 2D GaN, while a half-metallic state appears in 2D GaN after the adsorption of VA and VIIA atoms, which makes the latter higher work functions. Such regular modifications in physical properties of 2D GaN induced by adsorption could potentially allow use of this material in diverse electronic, optoelectronic, and spintronic applications.

Osteoarthritis is a relatively common disorder of articular deterioration related to cartilage damage, subchondral bone remodelling, inflammation and metabolism. Agents that can inhibit cartilage degradation and osteoclastogenesis are required for the prevention and treatment of osteoarthritis. Esculentoside A, the highest concentration triterpene saponin isolated from the root of Phytolacca esculenta, has commonly been used for the treatment of chronic bronchitis. However, the role esculentoside A plays in ameliorating osteoarthritis has not been reported. We found that esculentoside A suppresses the expression of IL-1β-induced inflammatory and metabolic factors (IL-6, IL-8, TNF-α, MMP2, MMP3 and MMP13). In addition, esculentoside A restrains osteoclast formation by inhibiting the marker gene expression of NFATc1 and c-Fos. Our results indicate that esculentoside A markedly suppresses IL-1β-induced NF-κB and MAPK signalling pathway activation in chondrocytes, and inhibits RANKL-induced osteoclast precursor generation. Finally, treatment with esculentoside A inhibits the progressive cartilage degeneration and osteoclastogenesis in osteoarthritis mouse models. In summary, these results demonstrate that esculentoside A could be a latent therapeutic reagent for the treatment of osteoarthritis.

Bone homeostasis requires a dynamic balance between osteogenesis and osteoclastogenesis, and osteolytic disorders are mainly attributed to aberrant osteoclastogenesis and bone resorption. Accumulating evidence has demonstrated that cyclin-dependent kinase 9 (CDK9) regulates some inflammatory diseases without affecting the cell cycle. Whether the specific inhibitor of CDK9, LDC000067 (abbreviated as LDC067), helps to prevent from osteolytic disorders has not been fully elucidated. Interestingly, this study demonstrated that LDC067 inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption in vitro, and suppressed the expression of osteoclast-related marker genes such as cathepsin K (CTSK), tartrate-resistant acid phosphatase (TRAP), dendrite cell-specific transmembrane protein (DC-STAMP), V-ATPase D2, calcitonin receptor (CTR) and nuclear factor of activated T cells cytoplasmic 1 (NFATc1). The bone protective effects of LDC067 can be partly explained by its suppression of nuclear factor-kappa B (NF-κB)-mediated NFATc1 activation via AKT signalling pathway. In keeping with the results obtained in vitro, inhibition of CDK9 with LDC067 was observed to delay subchondral osteolysis and substantially ameliorate LPS-induced osteolysis in murine calvaria. Collectively, these results highlight the positive effects of LDC067 in preventing osteolytic disorders and indicate that this CDK9 inhibitor may a promising therapeutic agent.

Transition metal salen complex MoO2–salen was successfully tethered onto amino-functionalized graphene oxide (designated as MoO2–salen–GO), which was tested in the epoxidation of various alkenes using tert-butylhydroperoxide or H2O2 as oxidant. Characterization results showed that dioxomolybdenum(VI) complex was successfully grafted onto the amino-functionalized graphene oxide and the structure of the graphene oxide was well preserved after several stepwise synthesis procedures. Catalytic tests showed that heterogeneous catalyst MoO2–salen–GO was more active than its homogeneous analogue MoO2–salen in the epoxidation of cyclooctene due to site isolation. In addition, the MoO2–salen–GO catalyst could be reused three times without significant loss of activity. Copyright © 2014 John Wiley & Sons, Ltd.

The size-dependent elastic modulus of tungsten layers and wires is predicted according to size-dependent melting temperature model. The elastic modulus decreases with decreasing of size and the drop becomes dramatically once the size decreases below 3 and 6 nm for layers and wires, respectively. Moreover, the softening of elastic modulus for wires is nearly twice as large as that for layers when size remains the same. The accuracy of the model is verified by experimental and atomistic simulations results.

Thermodynamic analytic models have been established first to describe the size dependences of Morin temperature TM and Neel temperature TN in hematite nanocrystals based on size-dependent cohesive ...

Pd−Ag bimetallic dendrites have been synthesized via a galvanic replacement reaction of Ag dendrites in a Na2PdCl4 solution. Scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis reveal that the resulting product is composed of partially depleted Ag dendrites covered with a rough surface with many Pd granules protruding by up to about 20 nm. High-solution TEM combined with EDX and selected area electron diffraction (SAED) confirms the formation of bimetallic interfaces between Pd and Ag. These Pd−Ag dendrites show up to four times higher catalytic activity toward the reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) than the best recently reported catalysts. This further enhancement over the already strong performance of similarly synthesized Au−Ag dendrites is explained by the presence of Pd, adding a hydrogen relay mechanism on top of the very effective electron r...

On the basis of a size-dependent cohesive energy model originally proposed for spherical nanoparticles, we develop an analytical model for the first time to determine the size- and shape-dependent catalytic activation energy of platinum nanoparticles through the introduction of a shape factor. The catalytic activation energy Ea(λ,D) was found to decrease with the decreasing size D or increasing shape factor λ, where the size effect is the principle factor and the shape effect is secondary. For platinum nanoparticles with the same size, the order is Ea(cube) > Ea(sphere) > Ea(octahedron) > Ea(tetrahedron) because λtetrahedron > λoctahedron > λsphere > λcube. The accuracy of the developed model was verified by the available experimental results.

Dendritic Ag/Au bimetallic nanostructures have been synthesized via a galvanic replacement reaction (GRR) of Ag dendrites in a chlorauric acid (HAuCl4) solution. After short periods of time, one obtains structures with protruding flakes; these will mature into very porous structures with little Ag left over. The morphological, compositional, and crystal structural changes involved with reaction time t were analyzed by using scanning and transmission electron microscopy (SEM and TEM, respectively), energy-dispersive X-ray spectrometry (EDX), and X-ray diffraction. High-resolution TEM combined with EDX and selected area electron diffraction confirmed the replacement of Ag with Au. A proposed formation mechanism of the original Ag dendrites developing pores while growing Au flakes cover this underlying structure at longer reaction times is confirmed by exploiting surface-enhanced Raman scattering (SERS). Catalytic reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) is strongly enhanced, implying promising applications in catalysis.

Three-dimensional-needled, carbon-fiber-reinforced silicon carbide matrix composites (C/SiC) were prepared by a chemical vapor infiltration and reactive melt infiltration method. It was found that two kinds of SiC existed in the C/SiC composites, that is, micro-β-SiC grains within the range of 5–15 μm and nano-β-SiC grains with a size of about 100 nm. The interface of C/SiC and the distribution of SiC showed evidence for the reaction mechanism of the reactive melt infiltration process.

Reducing the sizes of low dimensional materials leads to dramatic increase in the portion of surface/interface atoms. The properties of a solid are essentially controlled by related surface/interface energies. Although such changes are believed to dominate behaviors of nanoscale structures, little experience or intuition for the expected phenomena, especially for the size-dependence of the energies and their practical implications, are modeled analytically. In this contribution, the classic thermodynamics as a powerful traditional theoretical tool is used to model different bulk interface energies and the corresponding size dependences. During the modeling, an emphasis on size dependences of the interface energies is given, which is induced by size dependence of coherent energy of atoms within nanocrystals. It is found that solid–vapor interface energy, liquid–vapor interface energy, solid–liquid interface energy, and solid–solid interface energy of nanoparticles and thin films fall as their diameters or thickness decrease to several nanometers while the solid–vapor interface energy ratio between different facets is size-independent and equals to the corresponding bulk value. The predictions of the established analytic models without any free parameters, such as size and temperature, dependences of these four kinds of interface energies and related surface stress, correspond to experimental or other theoretical results. The above established models are suitable for low-dimensional materials with different dimensions and different chemical bond natures. Moreover, several related applications in the fields of nanophase transitions, nanocrystal growth, and self-diffusion of liquids are provided.

Silica-silver core-shell composite particles with uniform thin silver layers were successfully synthesized by a facile and one-step ultrasonic electrodeposition method. By electrolysis of the slurry consisting of preformed silica spheres and silver perchlorate without any additives, the homogenous composite particles can be prepared. The average size of single silver crystals in the composite is about 12 nm and the thickness of silver layer is 14{+-}2 nm. Moreover, the continuity of Ag distribution, the surface roughness and the thickness of silver layer are controllable by adjusting the current density (I), the concentration of electrolyte (C) and the reaction time (t). Optical properties of the composite particles with different silver content were also investigated. - Graphical abstract: Silica-silver core-shell composite particles with uniform thin silver layers are prepared by a facile and one-step ultrasonic electrodeposition method. Moreover, the continuity of Ag distribution, the surface roughness and the thickness of silver layer are controllable. Optical properties of the composite particles with different silver content were also investigated.

A model for size-dependent surface energy of elemental nanocavities is proposed in terms of size-dependent cohesive energy. It is found that the surface energy of elemental nanocavities increases with decreasing of the cavity size to several nanometers. The newly built model is validated to be in agreement with that based on some other theories. Moreover, an analytic model is developed to describe the size-dependent melting temperature of elemental nanocavities for the first time. The analytic results show that the melting temperature increases with decreasing of the size of nanocavities. The theoretical predictions confirm well to the available data of argon obtained by molecular dynamics simulations.

A simple thermodynamic model, originally developed for metals based on the Gibbs-Thomson equation and related considerations for homogeneous nucleation, has been extended to predict the solid-liquid interface energy gsl of organic crystals. The model predictions correspond to available experimental and other theoretical results for 38 organic crystals. Copyright # 2007 John Wiley & Sons, Ltd.

Temperature-dependent surface tension γlv(T) and its temperature coefficient γ′lv(T)=dγlv(T)/dT for liquid silicon and germanium (l-Si and l-Ge) are thermodynamically modeled based on an established model for surface energy of crystals. Combining the relationship among γlv(T), self-diffusion coefficient D and liquid viscosity η, temperature dependent D(T) function is also modeled. The model predictions correspond to the available experimental results. It is found that γlv(T)∝T, γ′lv(T)∝T and D(T)∝T3/2 at a certain temperature range (including T T m and T ⩾ T m where Tm is the melting temperature).

The temperature-dependent self-diffusion coefficient D ( T ) in liquid metals between the melting temperature T m and boiling point T b is modeled in terms of the relationship among D , liquid viscosity η , and liquid–vapor surface tension γ lv . The model predictions for D ( T ) correspond to available experimental and molecular dynamics (MD) simulations results for liquid alkali metals Li, Na, Rb and Cs, semi-metal Al, transition and noble metals Ni, Cu, Ag and Au.

Based on the previous models for bulk and size-dependent solid–liquid interfacial energy γ sl0 and γ sl ( r ) with the additional temperature-dependent melting enthalpy Δ H m ( T ) and improved Gibbs free energy difference functions g m ( T ) between crystal and liquid, γ sl ( r , T ) function is quantitatively modeled. It is found that the γ CNT values of Turnbull's undercooling experiments correspond to the model predictions for the nucleus–liquid interfacial energy rather than γ sl0 . This correspondence leads to the reexaminations on the classic nucleation theory. Moreover, the linear relationship between γ sl ( r , T ) and Δ H m / V is found to be always valid at any degree of undercooling where V is the molar volume. Finally, the size range of γ sl ( r , T ) for elements is also discussed.

A quantitative thermodynamic correlation method to describe the size dependent Langmuir adsorption isotherm is developed. According to the model, the equilibrium adsorption constant increases as material size decreases, which is in agreement with the literature data of acetic acid, valeric acid, oxalic acid, and adipic acid on anatase nanoparticles.

Through considering the packing density and the lattice contraction of Goldschmidt's premise, volume changes of elements crystals with different structures on melting are modeled. It is found that the predictions of the model are in agreement with the experimental and other theoretical results. In addition, the volume change of the solid–solid transition is also determined. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A simple formula without any free parameter is established to estimate surface energies of elemental metals of low-index surfaces, which is developed by modifying the classic broken-bond rule. The predicted results of the formula for 52 A1–A4 and sc elemental crystals are in agreement with experimental results and the first-principles calculations although deviations are present for several divalent sp metals.

Transition metal salen complex MoO2–salen was successfully tethered onto amino-functionalized graphene oxide (designated as MoO2–salen–GO), which was tested in the epoxidation of various alkenes using tert-butylhydroperoxide or H2O2 as oxidant. Characterization results showed that dioxomolybdenum(VI) complex was successfully grafted onto the amino-functionalized graphene oxide and the structure of the graphene oxide was well preserved after several stepwise synthesis procedures. Catalytic tests showed that heterogeneous catalyst MoO2–salen–GO was more active than its homogeneous analogue MoO2–salen in the epoxidation of cyclooctene due to site isolation. In addition, the MoO2–salen–GO catalyst could be reused three times without significant loss of activity. Copyright © 2014 John Wiley & Sons, Ltd.

This field study investigated the nitrogen concentrations in the shallow groundwater from an ephemeral stream and four land uses: cropland, two-year restored (2 yr) and five-years restored (5 yr) woodlands, fishponds, and the nitrogen flux in the riparian zone of Yuqiao Reservoir. The groundwater nitrate-N concentrations in cropland were the highest among the four land uses. Total dissolved nitrogen (TDN) and nitrate-N concentrations in the 2 yr woodland were significantly (p0.05) higher than in 5 yr woodland. The lowest nitrogen concentrations were detected in fishponds. Nitrate-N was the main form in cropland and 2 yr woodland, whereas both nitrate-N and dissolved organic nitrogen (DON) were the main species in 5 yr woodland and fishponds. But, ammonium-N was the main form in the ephemeral stream. During the rainy season, the groundwater flow with dissolved nitrogen drains from upland into the reservoir along the hydraulic gradient. The woodland between the cropland and reservoir could act as a buffer to retain shallow groundwater nitrogen. The dominant form of ammonium-N in the groundwater TDN pool in ephemeral stream indicated that nitrogen from the village and orchard in upland flowed into the reservoir via subsurface flow. The fishpond was not an important pollution source for nitrogen transfer via shallow groundwater.

A model for the size-dependent surface tension gammalv(D) of liquid droplets, free of any adjustable parameter, is presented in terms of the size-dependent surface energy gammasv(D). It is found that gammalv(D) drops monotonically with the size of the droplet in the nanometer region. Modeling predictions agree with computer simulations for sodium, aluminum, and water droplets. Meanwhile, the Tolman's equation is found to be valid for small particles, and the Tolman's length is always positive and becomes longer when the droplet size is decreased.

Oxovanadium(IV) and iron(III) salen complexes grafted onto amino-modified graphene oxide (NH2–GO) have been synthesized via a stepwise procedure and the prepared materials were used as heterogeneous catalysts in the aerobic oxidation of styrene. The structures of these materials have been thoroughly investigated using different characterization techniques such as XRD, N2 adsorption–desorption, TEM, FT-IR, diffuse reflectance UV-visible spectroscopy, ICP-AES, TEM, TG, Raman, and XPS. The results of XRD, N2 adsorption–desorption and TEM revealed that the structures of the prepared catalysts were well preserved. In addition, the results of FT-IR, diffuse reflectance UV-visible spectroscopy, ICP-AES, TG, Raman and XPS suggested that the oxovanadium(IV) and iron(III) complexes had been incorporated onto amino-modified graphene oxide (GO). It was found that the heterogeneous oxovanadium(IV) catalyst was more active than its homogeneous analogue in the epoxidation of styrene, using acetonitrile as solvent and air as the oxidant in combination with the sacrificial co-reductant isobutyraldehyde, due to site-isolation. Furthermore, the tethered vanadium catalyst was quite stable and could be recycled many times.