Comparaison de la morphologie du pied entre les enfants chinois et mongoliens

Knowledge of foot morphology is fundamental to optimize children’s footwear design. The aim of this study is to compare the foot morphology of Chinese and Mongolian children from 7 to 14 years old. Relative data of 339 Mongolian children and another matched 379 Chinese children were collected using 3D foot scanner. The findings of this study are as follows: i) the absolute foot length of Chinese children is significantly greater than that of Mongolian children of the same age; ii) Mongolian children show significantly greater heel width, toe thickness, lateral malleolus height, instep height and ball girth compared to Chinese children of the same age. The foot width of Chinese children is significantly greater than that of Mongolian children of the same age; iii) Chinese children have a higher risk of hallux valgus than Mongolian children of both sexes. Small variations in foot morphology discussed in this paper could be useful when considering the shoes design for Mongolian and Chinese children. © 2020 by the author(s)

A Modified Hyaluronic Acid–Based Dissolving Microneedle Loaded With Daphnetin Improved the Treatment of Psoriasis

Psoriasis is a common chronic immune-inflammatory disease. Challenges exist in the present treatment of psoriasis, such as difficulties in transdermal drug administration and severe side effects. We hope to achieve a better therapeutic outcome for psoriasis treatment. By using modified soluble microneedles (MNs) loaded with daphnetin, the psoriasis symptoms of mice, the abnormal proliferation of keratinocytes, and the secretion of inflammatory factors were significantly reduced. In vitro, daphnetin is proven to inhibit the NF-κB signaling pathway and to inhibit the proliferation of HaCaT cells and the release of inflammatory factors, especially CCL20. This research showed that the modified microneedle loaded with daphnetin optimized transdermal drug delivery and relieved the symptoms of psoriasis more effectively. The novel route of Daph administration provides a future research direction for the treatment of psoriasis

Improved thermal stability of polyethylene with rare earth trifluoromethanesulfonate

The thermal degradation of polyethylene (PE) is a free radical chain reaction, in other words, free radicals are the primary cause of combustion and degradation. Discovering proper compounds with radical trapping ability is critical for developing flame retardant PE composites. Herein, we introduced rare earth trifluoromethanesulfonate (RE(OTf)3), with radical trapping ability, into PE. The effects of ytterbium (Yb(OTf)3) and lanthanum (La(OTf)3) on the thermal stability and flammability properties of polyethylene (PE) were investigated systemically. Electron spin resonance (ESR) spectroscopy proved the free radical-trapping ability of La(OTf)3 and Yb(OTf)3. The results of thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) showed that Yb(OTf)3 could improve the thermal stability of PE more significantly compared with La(OTf)3. The flame retardancy of PE/intumescent flame retardant (IFR) composite was improved when 0.4 wt% IFR was substituted by RE(OTf)3. It changed the PE/IFR26 from UL-94 non-rated to V-0. Vertical flame test, limited oxygen index (LOI) and microscale combustion calorimeter (MCC) indicated that the effect of Yb(OTf)3 on the flame retardancy of PE was better than La(OTf)3. The improvement on the thermal stability and flame retardancy of PE is due to the combined action of anion and cation of RE(OTf)3. However, the different effects are attributed to the different reactivity of rare earth elements

Improved flame resistance and thermo-mechanical properties of epoxy resin nanocomposites from functionalized graphene oxide via self-assembly in water

The development of a green and facile strategy for fabricating ecofriendly, highly effective flame retardants has remain a major challenge. Herein, supermolecular aggregates of piperazine (PiP) and phytic acid (PA) have been self-assembled onto the graphene oxide (GO) surface in water to fabricate functionalized GO (PPGO). The chemical structure and morphology of PPGO are determined by the X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy along with the energy dispersive spectroscopy. Due to the introduction of organic component onto the surface of graphene oxide, the adhesion between PPGO and the epoxy resin (EP) matrix is enhanced. As a result, the storage modulus (E′) of EP composites is increased in addition to a better dispersion of PPGO. Compared with the pure EP, the flame resistance of EP/PPGO is significantly improved, exhibiting a 42% decrease in peak heat release rate (pHRR), 22% reduction in total heat release (THR). The reduced flammability of EP is attributed to the synergistic effects afforded by the gas dilution effect of piperazine, char-forming promotion effect of phytic acid and the creation of 'tortuous path' barrier effect of GO during burning. This work offers a green and facile approach for creating highly effective graphene-based flame retardants

Sulfonated Block Ionomers Enable Transparent, Fire-Resistant, Tough yet Strong Polycarbonate

Polycarbonate (PC) features high transparency and balanced mechanical properties, and thus is being growingly used for producing many high-end products, e.g., construction facades, sensors and 5G equipment. For these applications, PC is required to combine satisfactory fire retardancy and great toughness while retain its mechanical strength and optical transparency. However, existing either fire retardants or toughening agents fail to enable PC to achieve such a required performance portfolio due to their improper molecular designs. To overcome this challenge, we, herein, rationally design a series of sulfonated ionomeric fire retardants (sSEBS-M, M = Na+, Zn2+, Ce3+) by sulfonating and neutralizing styrene-ethylene-butylene-styrene (SEBS). The sSEBS-M can be well-dispersed within the PC matrix with phase domain sizes less than 500 nm. Chemical structures of sSEBS-M and their dispersion within the polymer matrix strongly correlate to their comprehensive performances in PC. Among three sSEBS-M ionomers, sSEBS-Ce endows PC with better comprehensive performances. With 1.5 wt% of sSEBS-Ce, the final PC achieves a high limiting oxygen index of 33.5% and a desired UL-94 V-0 rating, in addition to a 53% reduction in peak heat release rate and a comparable transparency to virgin PC. Moreover, its impact toughness and ductility are enhanced by 40% and 116% with tensile strength well-preserved. The integrated performance portfolios are superior to previous counterparts. This work offers a novel strategy for the design of multifunctional ionomer-based fire retardants for creating high-performance PC and reveals its structure-composition-property relationship in PC, which will enable PC to realize its practical applications in above-mentioned industries

A facile way to prepare phosphorus-Nitrogen-Functionalized graphene oxide for enhancing the flame retardancy of epoxy resin

In this paper, we have reported a facile way to functionalize graphene oxide (GO) via assembling a supermolecular aggregate of piperazine (PiP) and phytic acid (PA) onto the GO surface (PPGO) without using any organic solvent. The functionalization of GO is confirmed by the X-ray photoelectron spectrum (XPS), transmission electron micrographs (TEM) and Raman spectrum. The introduction of 3 wt% PPGO into epoxy resin (EP/PPGO3) results in notable suppression on the fire risk of epoxy resin. In addition, cone calorimeter tests showed that the peak heat release rate (pHRR) was decreased from 727.4 kW/m2 to 367.5 kW/m2 (49%), and the peak smoke production rate (pSPR) was decreased from 0.2316 m2/s to 0.1379 g/s (40%). The improved flame-retardant performance of EP nanocomposites is most likely due to a tripartite cooperative effect from the key components (piperizine, phytic acid, and GO). This strategy demonstrates a facile and efficient approach for fabricating highly effective graphene-based flame retardants for polymers

Fabrication of fullerene-decorated graphene oxide and its influence on flame retardancy of high density polyethylene

Fullerene (C-60) decorated graphene oxide (GO), denoted as GO-d-C-60, was synthesized through a three step chemical process, including acylating chlorination of GO, amino-functionalization of GO and addition reaction of C-60 molecules with amino groups, with the purpose of promoting the dispersion of GO in high density polyethylene (HDPE) and further improving thermal stability and flame retardancy of HDPE/ GO composite. Infrared spectroscopy (IR), transmission electron micrographs (TEM) and X-ray photoelectron spectroscopy (XPS) proved that about 2.3 wt.% of C-60 molecules, with the size of about 40-70 nm, were bonded onto the surface of GO and mainly located on the edge of GO sheets. The chemical decoration made GO-d-C-60 to have better dispersion in HDPE than GO, favoring the formation of compact and integrated char barriers when heated or ignited. Consequently, GO-d-C-60 improved the thermal stability and flame retardancy of HDPE more effectively than pristine GO, due to the assembly of the barrier effect of GO and the radical-trapping effect of C-60. (C) 2016 Elsevier Ltd. All rights reserved

A hyperbranched P/N/B-containing oligomer as multifunctional flame retardant for epoxy resins

Flame-retardant epoxy resins (EPs) with superior optical, mechanical and dielectric properties are highly desired in high-tech industries. In this work, a multifunctional hyperbranched additive (BDHDP) was synthesized for EPs. Our results showed that BDHDP catalyzed the curing of epoxy resin because of its tertiary amine and hydroxyl groups. At a low addition level (<3.0 wt%), BDHDP increased the glass-transition temperature and maintained the optical transmittance of epoxy thermoset. Meanwhile, BDHDP improved the mechanical strength and toughness, and reduced the dielectric constant and loss of EP because of the rigid phosphaphenanthrene groups and intra-molecular cavities. Moreover, BDHDP reduced the heat release and smoke generation during the EP combustion. Adding 1.5 wt% of BDHDP led to a UL-94 V-0 rating, and reduced the total smoke production by 16.4%. Hence, this study offers an effective method to create transparent EP thermosets with outstanding mechanical, dielectric and fire-retardant properties via incorporating a P/N/B-containing hyperbranched oligomer

Synthesis of decorated graphene with P, N-containing compounds and its flame retardancy and smoke suppression effects on polylactic acid

Functionalized graphene (PNFR@RGO) has been fabricated by decorating chemically reduced graphene oxide (RGO) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and branched polyethylenimine (BPEI) in this work. PNFR@RGO is then used to reduce the flammability of polylactic acid (PLA) via a melt compounding protocol. X-ray photoelectron spectroscopy (XPS) and Infrared spectroscopy (IR) have confirmed the successful fabrication of the target PNFR@RGO. The chemical decoration introduces phosphorus and nitrogen elements to the GO which can combine the formation of compact char barriers from graphene nanosheets and the elimination of free radicals when ignited or heated. The results show that the degradation temperature in air is increased and the heat release rate (HRR) is reduced. With the addition of 4 wt% PNFR@RGO, the average specific extinction area (ASEA) and the total smoke release (TSR) of PLA are noticeably suppressed by 92% and 79%, respectively. This is attributed to the combination of the corridor barrier functions of RGO and the radical-scavenging effects of PNFR

Research on the Diffusion Model of Cable Corrosion Factors Based on Optimized BP Neural Network Algorithm

Corrosion factors enter the cable via diffusion and penetration from the defect position of the cable or the connection position between the anchoring system and the cable section, seriously affecting the cable’s durability. Exploring the transmission mechanism of corrosion factors in the cable structure is essential to reveal the durability and the long-term performance of the cable structure and to judge the corrosion damage of steel wires in the cable structure. Based on the machine learning (ML) method and the analytical solution of Fick’s second law, the laws between different temperatures, humidity, cable inclinations, cable defect areas, etc., and the diffusion coefficient of corrosion factors and the concentration of surface corrosion factors are obtained, also a spatial diffusion model of corrosion factors is established. According to the research, the optimum simulation result is achieved by employing the optimized back propagation (BP) neural network algorithm, which has a faster convergence speed and better robustness. Although ambient temperature, humidity, and corrosion time all impact the diffusion rate of corrosion factors, the tilt angle of the cable and the size of cable defects are the main factors influencing the diffusion coefficient of corrosion factors and the concentration of surface corrosion factors. The error between the concentration of corrosion factors calculated by the model in this article and the measured values at each spatial point of the cable is controlled within 15%, allowing for the spatial diffusion of corrosion factors to be effectively predicted and evaluated in practical engineering