Design of a novel comfort liner for a motorcycle helmet

Natural fibres are nowadays increasingly being employed for producing protective clothing and sportswear. Due to economic and/or environmental considerations they are replacing synthetic materials. The present work provides an insight into the design and development of a novel comfort liner for a motorcycle helmet. The liner is produced from wool and Tunisian alfa fibre. The plant of the alfa fibre is abundantly available in Tunisia. Furthermore, we describe a design concept for a liner that uses these natural fibres and phase change material to improve sweat absorption and perception of thermal comfort. The raw material, the processes involved and the solution to use the phase change material are analysed. The novel comfort liner can facilitate breathability and evaporative transfer of heat in the safety helmet. In addition, it increases comfort, well-being, and provides an indirect message to use natural fibres for textile support to preserve our environment.     

Prediction of Duration Limited Exposure for Participants Wearing Chemical Protective Clothing in the Cold

The suitability of the IREQ (insulation required) index for predicting the thermal responses of 6 participants wearing chemical protective clothing was tested during exercise at -20 and -25 °C. IREQ was used to calculate duration limited exposure (DLE). Measured DLE correlated (r= .899, p < .001) with the predicted DLE. In exposures exceeding 40 min, however, the predicted DLE tended to be 10-20 min too short compared to the measured one. During short exposures the prediction was 5-20 min too long. The results show that IREQ overestimated the cold strain in participants wearing chemical protective clothing during cold exposures longer than 40 min. Nevertheless, predicted DLE never exceeded measured times and thus the prediction was always safe from the occupational point of view.     

Parallel and Serial Methods of Calculating Thermal Insulation in European Manikin Standards

Abstract

Standard No. EN 15831:2004 provides 2 methods of calculating insulation: parallel and serial. The parallel method is similar to the global one defined in Standard No. ISO 9920:2007. Standards No. EN 342:2004, EN 14058:2004 and EN 13537:2002 refer to the methods defined in Standard No. EN ISO 15831:2004 for testing cold protective clothing or equipment. However, it is necessary to consider several issues, e.g., referring to measuring human subjects, when using the serial method. With one zone, there is no serial-parallel issue as the results are the same, while more zones increase the difference in insulation value between the methods. If insulation is evenly distributed, differences between the serial and parallel method are relatively small and proportional. However, with more insulation layers overlapping in heavy cold protective ensembles, the serial method produces higher insulation values than the parallel one and human studies. Therefore, the parallel method is recommended for standard testing.     

Thermal Strain in Fire Fighters While Wearing Task-Fitted Versus EN 469:2005 Protective Clothing During a Prolonged Rescue Drill

Fire fighters are normally overprotected during their working hours because of the tendency to keep the personal protection level sufficiently high in case of the worst possible scenarios. This study investigated the effects of task-fitted protective clothing on thermal strain in fire fighters as compared to EN 469:2005 protective clothing during a prolonged (2 1/2 hrs) job-related rescue drill under neutral and hot climates. The subjects were 23 healthy, physically fit professional male fire fighters aged 26–44 years. Measurements included cardiovascular and thermal responses and subjective assessments. Wearing task-fitted clothing during rescue tasks in a neutral climate considerably reduced total thermal and cardiovascular strain in prolonged rescue work. The fire fighters also perceived physical work as significantly harder on average, and reported more intense subjective discomfort while wearing EN 469:2005 as compared to task-fitted clothing.     

MPP协同MF@ADP阻燃低密度聚乙烯性能研究*

为提高低密度聚乙烯（LDPE）阻燃性能和阻燃LDPE复合材料的力学性能与抑烟性能,采用原位聚合法制备三聚氰胺-甲醛（MF）树脂包覆二乙基次磷酸铝（ADP）的MF@ADP微胶囊,再引入三聚氰胺聚磷酸（MPP）与MF@ADP进行协效复配,熔融共混制备阻燃LDPE复合材料。通过氧指数、热重分析、力学测试和烟密度测试等研究复合材料的阻燃、力学和抑烟性能。研究结果表明:MF@ADP微胶囊能改善阻燃剂与复合材料之间的相容性,与MPP复配构成的磷-氮膨胀阻燃体系能有效提高LDPE的抑烟性能;当MF@ADP∶MPP的质量比为2∶1时,材料的LOI达到了30.6%,垂直燃烧测试达到UL-94 V0级,拉伸强度为11.8 MPa,且形成的P/N/O高聚物炭层稳定性更高,可减少LDPE燃烧释放的烟雾量。     

冷冲击条件下饱水煤样结构损伤规律研究*

为探究煤体在冷冲击影响下强度损伤特征及细观结构演化规律,通过自制低温冲击系统,利用声发射、金相显微镜宏观与细观手段结合的方法,基于ImageJ图像分析软件分别对干燥煤样、饱水煤样冷冲击前后细观结构演化进行量化表征,并通过测试渗透率验证煤体结构变化带来的增透效果,研究结果表明:在煤体中超声波波速随冷冲击温度降低而下降;相同时间内,冷冲击温度越低,声发射振铃计数表现越活跃,煤体释放能量愈大,致裂效果越显著;经冷冲击后的饱水煤样相对于干燥煤样会产生更多的斜向新生裂隙,新萌生裂隙与原生裂隙交汇贯通形成絮状网格,其渗透效果显著提升;随冲击温度的降低,抗压强度、弹性模量均增大。研究结果可为低温改善煤层透气性,增产煤层气及矿井瓦斯灾害防治技术提供理论依据。     

机械力化学活化HPW-TiO_2/膨润土光催化降解甲基橙

采用溶胶-凝胶法制备了磷钨酸(HPW)改性TiO_2,并固载于膨润土上,再经机械力化学活化,得到机械力化学活化HPW-TiO_2/膨润土(MCA-HPW-TiO_2/膨润土)复合光催化剂。采用XRD,SEM,EDS技术对复合光催化剂进行了表征,并将其用于甲基橙的紫外光催化降解。表征结果显示:活性组分TiO_2和HPW成功固载于膨润土上;在机械力化学活化作用下,膨润土层间结构遭到破坏,TiO_2的XRD特征峰形呈弥散状态。实验结果表明:机械力化学活化作用对HPW-TiO_2/膨润土的光催化性能提升效果显著;在酸性及近中性条件下MCA-HPWTiO_2/膨润土均具有较高的催化活性;在溶液p H 6.2、初始甲基橙质量浓度10 mg/L、反应时间180 min、MCAHPW-TiO_2/膨润土投加量1 g/L的条件下,甲基橙去除率达88.27%;该光催化降解过程符合一级动力学模型。     

土壤微生物呼吸热适应性与微生物群落及多样性对全球气候变化响应研究

土壤微生物呼吸热适应性被认为是决定陆地生态系统对全球变暖反馈作用的潜在重要机制,可能显著改变未来的气候变化趋势,然而,土壤微生物群落结构变化如何引起土壤微生物呼吸热适应性的研究目前尚存争议.该文针对气候变化对土壤微生物呼吸的影响研究,梳理了当前对土壤微生物呼吸的热适应性是否存在的争议和不同观点与结论,综述了气候变化对土...     

神经毒剂沙林的破坏机理研究

采用VAMP和密度泛函程序DMol3计算了沙林的生成热,并用VAMP-PM3/UHF半经验方法对沙林裂解的过渡态进行了优化计算,共发现9种过渡态,据此判断化学键断裂的难易顺序为P=O＞P-F＞P-O＞C-O＞P-C＞C-C＞C-H; C-H键断裂的活化能最小,可能与氢原子迁移到氧原子上有关.活化能小于相应的键解离能,计算结果能解释沙林的质谱数据.计算结果对使用低当量小型核武器破坏沙林等生化武器(核除剂)的可行性提供了能量上的参考,即试图通过计算得出有效的原位破坏沙林等生化战剂所需的最低能量,进而研究使用低当量小型核武器破坏沙林等生化武器的可行性.     

Activation of sulfite by metal-organic framework-derived cobalt nanoparticles for organic pollutants removal

Sulfite (SO₃²⁻) activation is one of the most potential sulfate-radical-based advanced oxidation processes, and the catalysts with high efficiency and low-cost are greatly desired. In this study, the cobalt nanoparticles embedded in nitrogen-doped graphite layers (Co@NC), were used to activate SO₃²⁻ for removal of Methyl Orange in aqueous solution. The Co@NC catalysts were synthesized via pyrolysis of Co²⁺-based metal-organic framework (Co-MOF), where CoO was firstly formed at 400℃ and then partially reduced to Co nanoparticles embedded in carbon layers at 800℃. The Co@NC catalysts were more active than other cobalt-based catalysts such as Co²⁺, Co₃O₄ and CoFe₂O₄, due to the synergistic effect of metallic Co and Co_xO_y. A series of chain reaction between Co species and dissolved oxygen was established, with the production and transformation of SO₃^•−, SO₅²⁻, and subsequent active radicals SO₄^•− and HO•. In addition, HCO₃⁻ was found to play a key role in the reaction by complexing with Co species on the surface of the catalysts. The results provide a new promising strategy by using the Co@NC catalyst for SO₃²⁻ oxidation to promote organic pollutants degradation.