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Adolescence is a critical period of rapid bone mass growth, and achieving higher bone mineral density (BMD) during this period can help prevent osteoporosis. The effects of metallic mercury on bone health remain unclear and controversial. Numerous studies have focused on perimenopausal women and older adults, and the association of blood mercury with bone mineral density in adolescents has not been discussed. This study aimed to collect data from the National Health and Nutrition Examination Survey (NHANES) 2011–2018 to explore the association of blood mercury levels with bone mineral density in adolescents. Based on the results of statistical analyses of 2818 participants, we found that blood mercury levels were negatively associated with bone mineral density in adolescents, although not significantly. Additionally, the trend in bone mineral density with changes in blood mercury was different in male and female adolescents. We also found an inverted U-shaped association between blood mercury and bone mineral density in male and Mexican American adolescents. This suggests that increased blood mercury levels within a range may be beneficial for bone health in male adolescents (inflection point: 5.44 nmol/L) and Mexican-American adolescents (inflection point: 5.49 nmol/L), while higher blood mercury levels may be detrimental to bone health. Due to the design of this study, more prospective studies are needed to confirm our findings.

The use of weak bases as accelerators for reversible addition-fragmentation chain transfer radical polymerization (RAFT) of isoprene is demonstrated. Adding weak bases to RAFT polymerization, the c...

In this paper, γ-valerolactone (GVL), a bio-based polar solvent, was applied as green solvent for iron(III)-catalyzed AGET ATRP without any external ligand. GVL is a fully degradable, non-toxic green solvent and has complex ability to iron halide complexes through –OCO- group. GVL as the solvent and the ligand for AGET ATRP of MMA in a controlled manner, as proved by kinetic study, the low PDI values and the increase in polymer molecular weight versus monomer conversion. Chain re-initiation experiments and 1HNMR characterization were conducted to further confirm the living feature.

A cross-linked chitosan-PVA spherical hydrogel (CSH) was synthesized and its structure was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The physical and chemical properties of CSH, such as acid resistance and swelling, were determined. Finally, Cu(II) ion removal by the CSH was investigated, and the effects of experimental parameters, including pH, adsorption time, and regeneration performance were examined. Results revealed that CSH has outstanding stability in strong acid solution, thus extending the useful pH range as an adsorbent material. The maximum capacity of CSH for Cu(II) was obtained to be 62.1 mg/g at 25 °C for 24 h. The adsorption process was best described by a pseudo-second-order kinetic model, while isotherm modeling revealed that the Langmuir equation better described the adsorption of Cu(II) on CSH. Moreover, the loaded CSH can be easily regenerated by the HCl-washing method and reused repeatedly for Cu(II) adsorption for up to five cycles.

Stimuli-responsive polymer materials have a promising potential application in many areas. However, integrating multi-stimuli into one elastomer is still a challenge. Here, we utilized boronic esters and anthracene to prepare a cross-linked poly(styrene-butadiene-styrene) (SBS) which was endowed with responsiveness to three stimuli (light, heat, and alcohols). SBS was first functionalized with a certain amount of dihydroxyl groups via a thiol-ene “click” reaction between unsaturated double bonds in PB block and thioglycerol. Then, 9-anthraceneboronic acid was applied to form a cross-linked SBS network upon heat and ultraviolet radiation (λ = 365 nm). The prepared elastomer was demonstrated to be stimuli-responsive based on the dynamic nature of boronic esters and the reversible dimerization of anthracene. In addition, the mechanical properties of the elastomer could be regulated continuously owing to the stimulus responsiveness to ultraviolet or heat.

Both poly(ethylene oxide)-block-poly(N-vinylcarbazole) (PEO-b-PVK) diblock copolymer and fullerene-capped poly(ethylene oxide) (PEO-C60) were synthesized in this work. The former was obtained via reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate process whereas the latter via click reaction of azido-capped poly(ethylene oxide) with fullerene-C60. Both of the amphiphiles were incorporated into epoxy to obtain the nanostructured thermosets. It was found that the PVK-C60 charge transfer complexes were formed in the ternary thermosetting blends of epoxy, PEO-b-PVK and PEO-C60. The nanostructured epoxy thermosets containing PVK or/and fullerene displayed the enhanced dielectric constants whereas the dielectric loss remained almost unchanged. Nonetheless, the dielectric constants were significantly decreased while both PEO-b-PVK and PEO-C60 were simultaneously incorporated into the thermosets. The depression in dielectric constant is attributable to the formation of the charge transfer complexes of PVK with fullerene-C60. It was found that the dielectric constants can be modulated with the contents of the PVK-C60 charge transfer complexes.

In this contribution, we reported the investigation of epoxy toughening via the formation of nanostructures by the use of poly(e-caprolactone)-block-polyisoprene (PCL-b-PI) diblock copolymer. The novel diblock copolymer was synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer polymerizations. This diblock copolymer can be used to access the nanostructures of epoxy thermosets. Transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) showed that the nanostructured thermosets were successfully obtained. In the nanostructured thermosets, the spherical or vesicular polyisoprene microdomains were dispersed in continuous epoxy matrix. It is the formation of the PI nanophases that endowed the thermosets with significantly improved fracture toughness.

Herein, a quasi-coral-like nanostructure of SnO 2 /SnO@C composite (SnO x @C) has been prepared by a facile one-pot hydrothermal and subsequent carbonization strategy. This interesting architecture of ultrasmall SnO x nanoparticles embedded into quasi-coral-like carbon matrix can not only accommodate the volume change of SnO 2 , but also improve the conductivity of whole SnO x @C electrode. In consequence, the SnO x @C exhibits outstanding lithium storage.

The main issues spinel lithium titanate (Li4Ti5O12) anodes suffered from are poor electrical conductivity and low theoretical capacity, which impede the practical application of Li4Ti5O12 anodes in power lithium-ion batteries. Herein, the improvement in rate capability and specific capacity of Li4Ti5O12 anodes has been achieved by facile two-phase formation and nanostructure engineering strategy. When evaluated as anode material for lithium-ion batteries, the as-prepared TiO2 in-situ decorated Li4Ti5O12 nanobelts exhibit impressive performance, delivering a high reversible specific capacity of 185.1 and 161.2 mAh g−1 at 20 and 200 mA g−1 after 250 and 2000 cycles, respectively. More importantly, a capacity of 135.6 mAh g−1 could be retained at a high rate of 2000 mA g−1 even after 5000 cycles, showing excellent rate property and cycle life. Thus excellent performance may make them a promising anode material for advanced lithium-ion batteries.

In this contribution, we reported the preparation of the nanostructured epoxy thermosets containing poly( N -vinylcarbazole) (PVK) microdomains. Toward this end, we first synthesized poly( N -vinylpyrrolidone)- block -poly( N -vinylcarbazole)- block -poly( N -vinyl pyrrolidone) (PVPy- b -PVK- b -PVPy) triblock copolymer via sequential reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process; then this triblock copolymer was incorporated into epoxy to obtain the nanostructured thermosets. It was found that reaction-induced microphase separation occurred in the mixtures of this triblock copolymer with epoxy. The formation of the PVK microdomains in epoxy thermosets were investigated by means of transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Owing to the creation of PVK nanophases, the nanostructured epoxy thermosets became light-emissive under ultraviolet irradiation. The photoluminescent behavior is attributable to the formation of the excimers within the PVK microdomains. Compared to control epoxy, the nanostructured thermosets significantly displayed the enhanced dielectric constants due to the formation of PVK nanophases. The enhanced dielectric constants resulted from the dominant contribution of electron polarization and interfacial polarization with the formation of PVK nanophases.

The nanostructured thermosets involving epoxy and poly(methyl methacrylate)-grafted poly(vinylidene fluoride-co-trifluoroethylene) copolymer (P(VDF-TrFE)-g-PMMA) were successfully prepared in this work. The P(VDF-TrFE)-g-PMMA graft copolymer was synthesized via the atom transfer radical polymerization of methyl methacrylate (MMA) with poly(vinylidene fluoride-co-chlorotrifluoroethylene) copolymer as the macromolecular initiator. It was characterized by means of proton nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry, and dynamic laser scattering. Owing to the amphiphilicity, this graft copolymer can be readily incorporated into epoxy to obtain the nanostructured thermosets. Transmission electron microscopy showed that the spherical nanophases with a size of 10–100 nm in diameter were dispersed into the continuous epoxy matrix, depending on the content of P(VDF-TrFE)-g-PMMA. The measurement of dielectric properties showed that the modified epoxy ther...

Improved structural stability and conductivity are urgently demanded for SnO2 materials to be lithium-ion battery anodes. To this end, here a seemingly capsule-like composite composed of SnO2 nanorods encapsulated within a porous capsule-like carbon matrix (SnO2 NRs@PC) has been synthesized by a well-designed method. It is thus revealed that the structural advantages of the SnO2 NRs@PC including one-dimensional nanoscale sizes, porous carbon encapsulation, large specific surface area and especially chamber-confined effect can synergistically contribute to the good structure durability and enhanced electrochemical kinetics for lithium storage. Therefore, the as-synthesized SnO2 NRs@PC composite, as a promising lithium-ion battery anode, shows desirable cyclic performance, releasing high capacities of 985 and 852 mAh/g at 200 and even 1000 mA/g after 300 and 550 cycles, respectively.

In this contribution, we reported the synthesis of a hyperbranched block copolymer composed of poly(e‐caprolactone) (PCL) and polystyrene (PS) subchains. Toward this end, we first synthesized an α‐alkynyl‐ and ω,ω′‐diazido‐terminated PCL‐b‐(PS)₂ macromonomer via the combination of ring‐opening polymerization and atom transfer radical polymerization. By the use of this AB₂ macromonomer, the hyperbranched block copolymer (h‐[PCL‐b‐(PS)₂]) was synthesized via a copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition (i.e., click reaction) polymerization. The hyperbranched block copolymer was characterized by means of ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography. Both differential scanning calorimetry and atomic force microscopy showed that the hyperbranched block copolymer was microphase‐separated in bulk. While this hyperbranched block copolymer was incorporated into epoxy, the nanostructured thermosets were successfully obtained; the formation of the nanophases in epoxy followed reaction‐induced microphase separation mechanism as evidenced by atomic force microscopy, small angle X‐ray scattering, and dynamic mechanical thermal analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 368–380

A pitch cone based geometry design method considering line contact is proposed for intersected beveloid gears. The proposed pitch cone design applies the spatial gearing model to determine working pitch cone angles and working spiral angles. For the determination of geometry design parameters, a computer program which incorporates pitch cone design and line contact condition was developed. To illustrate the meshing characteristics, example studies with three groups of geometry parameters were performed by unloaded and loaded tooth contact analysis. Through the analysis, the influences of misalignments, torque load and angle between the first principal directions of the tooth surface curvatures (FPD-angle) on the mesh were investigated. The results show that: compared with axial position errors, shaft angle errors have a more detrimental influence on both the contact path and transmission error. Both FPD-angle and torque load have an obvious effect on this type of gearing. Finally, a practical experimental setup for intersected beveloid gearing with small shaft angle was performed and loaded tooth bearing tests were conducted to demonstrate the proposed design procedure and the theoretical simulation models. The experimental results compared well with the simulation.