短纤维/硅树脂复合材料的性能研究

分别用ＰＥＴ短纤维和硅灰石（无机针状晶须）增强甲基乙烯基硅树脂，研究了纤维长度、含量与复合材料力学性能的关系，并考察了增强纤维对硅树脂热稳定性的影响。结果表明：ＰＥＴ短纤维增强硅树脂复合材料的拉伸强度、模量和硬度显著提高，断裂伸长率下降；ＰＥＴ纤维长径比在１８０～３００范围内时，复合材料的拉伸强度增大；硅灰石增强的复合材料强度、模量及硬度提高相对较小，断裂伸长率随强体用量增多，先增加而后降低，存在     

Evaluation of response of multiple sclerosis (MS) relapse to oral high-dose methylprednisolone: usefulness of MS functional composite and Expanded Disability Status Scale

To compare the usefulness of multiple sclerosis functional composite (MSFC) to the Expanded Disability Status Scale (EDSS) in assessing functional changes related to relapse. A prospective 12-week follow-up study after relapse was conducted among 14 multiple sclerosis (MS) patients treated with oral high-dose (1 g) methylprednisolone for 3 days. MSFC and the EDSS were assessed on day 0, before treatment and, 1, 4 and 12 weeks afterwards. In relapses, EDSS (2.5 ± 1.2 to 3.8 ± 1.0) and z-score of the MSFC (0.15 ± 0.58 to −0.59 ± 0.70) worsened. After 1 week of treatment, the EDSS improved (3.3 ± 1.2; P  =   0.002) while the MSFC did not change significantly. At week 4, EDSS improvement was maximal (2.8 ± 1.3; P  =   0.001). At week 12, EDSS remained stable whereas z-score continued improving (0.26 ± 0.74). z-9peg-hole-test was the most sensitive subtest. There was correlation between baseline values of both scales (−0.620, P  <   0.05) and between changes due to relapse (−0.535, P  <   0.05). 78.5% of patients had improved at week 4 (35.7% at week 1). There were no serious adverse effects. MSFC and the EDSS were sensitive to changes due to relapses, although the dynamics for restoring baseline function were different. Our data support the usefulness of both scales in clinical trials, providing complementary information about outcome of MS patients with relapses.     

Evolutive Models for the Geometry and Heat Conductivity of an Intumescent EVA-ATH Composite during Its Thermal Degradation

Reliable predictions from numerical simulations in fire safety applications require knowledge of the combustible materials’ properties in their initial and thermally degraded states. The thermal conductivity of the sheath material of electrical cables, present in massive amounts in industrial plants, is addressed here. An evolutive conceptual model is proposed for the morphology of this intumescent polymer composite during its thermal degradation. It accounts for the multiscale structure and anisotropy observed during a thorough characterization based on tomographic images of samples at representative stages of the degradation. The evolution of the geometrical characteristics during the process is linked to chemical advancement parameters according to a reasoned scenario based on physical arguments and balance considerations. The anisotropic thermal conductivity tensor can be deduced from the geometry by a nested application of classical models. Ultimately, the conductivity is obtained as an analytic function of the chemical advancement and temperature. The model predictions were validated by comparisons with direct numerical solutions of thermal problems in the fully described geometry provided by the tomographies, and with measurements from the literature. The methodology and conceptual tools can be of interest for the treatment of other materials and in other contexts of application.     

A 31-year review of composite radial forearm free flaps for head and neck reconstruction

The aim of this study was to report the patient characteristics and radial fracture rates in a consecutive series of composite radial forearm free flap (CRFFF) for head and neck reconstruction over a 31-year period. The patients were identified from between 1990 to 2020 inclusive from theatre records and records from previous analyses at the Unit on free flap outcomes. Electronic case notes were accessed where available, to gather information on the operation, histopathology, and radiographs. Patients were categorised into three groups for analysis: (1) new oral cancers with a composite radial being the first choice of flap, (2) new oral cancers with a composite radial being the choice of flap following compromise of another bony flap, (3) osteoradionecrosis (ORN) cases. There were 103 CRFFF cases, median (IQR) age 69 (59-80) years, comprising 78 (Group 1), 5 (Group 2) and 20 (Group 3). The CRFFF failure rate was 6% (6/103) and the radius fracture rate was also 6% (6/103), both with 95% confidence interval 2.2-12.2%. Of the 6 radius fractures, 1 underwent surgical management (rush nailing), 1 died in hospital and the others managed with cast immobilisation. Two-year overall survival after surgery for the103 patients was 54% (SE 5%), while 5-year survival was 40% (SE 5%). In conclusion, in spite of the familiarity with other bone flaps such as fibular free flap, DCIA, scapula, and the limited bone stock and potential fracture related morbidity associated with the CRFFF, this flap still has a place in the surgical reconstructive armamentarium.     

Impacts of Thermal and Mechanical Cycles on Electro-Thermal Anti-Icing System of CFRP Laminates Embedding Sprayable Metal Film

The aircraft electro-thermal anti-icing system that can guarantee flight safety may be affected by periodic heating and cyclic aerodynamic force during long-term flight missions, which seems to be a potential threat to ice protection. This paper aims to investigate the impacts of thermal and mechanical cycles on heating elements of the electro-thermal anti-icing system. Specimens were manufactured with CFRP (carbon fiber reinforced polymer) laminated composite, glass fiber prepreg and copper screen, in which sprayable metal film (SMF) was embedded as the heating element. The study focuses on electric resistance variation of SMF and functional fatigue life under the cycling load. Thermal cycling tests were carried out in an insulated chamber where the specimens were heated up to 80 °C and then cooled down to −55 °C for 1000 cycles. Mechanical cycling tests were conducted on a fatigue testing machine where the specimens were imposed on tension-compression loading for 10⁶ cycles. Results showed that the electric resistance of SMF increased with the number of loading cycles. The resistance was increased by 20% and the heating power was decreased by 16.67% after 1000 thermal cycles. During the mechanical cycling tests, it was found that the heating element was destructed before the structural failure, which indicated that the fatigue life of function was lower than that of the structure.