Reinforcing Paper Strength by Dual Treatment of a Cationic Water-soluble Polymer and Cellulose Nanofibril

Cellulose nanofibril (CNF) was used as the anionic component of two dual strengthening systems wherein polyamidopolyamine epichlorohydrin resin (PAE) or cationic starch (CS) was used as the cationic component. Their strengthening effects were investigated for low-basis-weight (30 g/m²) paper composed of a mixture of fully bleached softwood and hardwood pulp in a 4:1 mass ratio. Using the PAE/CNF or CS/CNF dual system, it was generally easier to achieve higher wet and dry tensile strengths of paper compared to the paper using the single PAE or CS system. For example, the paper using the PAE (0.4%)/CNF (0.3%) dual system exhibited 89% higher wet tensile strength than the paper using the single PAE (0.4%) system, and the paper using CS (1.3%)/CNF (0.3%) dual treatment showed 21% higher dry strength than that using the single CS (1.3%) system. However, the PAE/CNF system only showed small improvement in the dry strength of paper (11% higher than that of paper using the single PAE system), so did the CS/NFC system on wet strength improvement (only 17% higher than that of paper using the single CS system).     

Enhancing selectivity and reducing cost for dehydrogenation of dodecahydro-N-ethylcarbazole by supporting platinum on titanium dioxide

N-ethylcarbazole/dodecahydro-N-ethylcarbazole (NECZ/12H-NECZ) was a promising system for hydrogen storage applications. 1.0 wt% Pt/TiO₂ was regarded as the optimal loading in Pt/TiO₂ catalyst applied in the 12H-NECZ dehydrogenation reaction. The hydrogen release amount, selectivity to NECZ and TOF of 12H-NECZ dehydrogenation are 5.75 wt %, 98% and 229.73 min⁻¹ at 453 K. Compared with the commercial 5.0 wt% Pd and Pt-based catalysts, it exhibited very high activity, selectivity and stability for 12H-NECZ dehydrogenation with low Pt loading. Combined with the XRD, XPS, HRTEM, TPR analysis, it was indicated that the enhanced catalytic performance was due to the SMSI (strong metal-supporting interaction) between Pt and TiO₂ support, which accelerated the rate-limiting step and enhanced the whole dehydrogenation reaction. This work may be beneficial for the commercial application of Pt/TiO₂ catalysts in the Liquid Organic Hydrogen Carrier (LOHC) system.     

《蚕丝被》国家标准修订解析及实施建议

近年来蚕丝被产业保持蓬勃发展的良好势头,但也出现了丝绵增重等不良现象。为解决蚕丝被的相关问题,满足高质量发展的要求,有关方面组织开展了国家标准的修订工作。文章介绍GB/T 24252-2009《蚕丝被》国家标准的修订背景及原则,全面解析标准的主要修订内容,着重强调蚕丝被填充物(蚕丝绵)不允许增重,具体指出标准不足之处,初步提出了标准的实施建议,以便于蚕丝被生产、消费、检验等相关方面更好地理解、领会和应用标准,从而推动提高蚕丝被产品质量、规范蚕丝被市场秩序、维护产销双方合法权益,以及促进行业健康稳定发展。     

往复加载下预制承台-桩连接构造受力性能

在交通不便、土地资源稀缺及环保要求高的山区公路高架桥梁建设中,为充分利用一体化架桥设备桥面输送预制构件的优势、最大限度地实现全预制桥梁的建造需求,提出一种将现浇承台改为预制承台的方案。针对预制承台与桩连接构造受力安全可靠性问题,按照1/3的缩尺比设计制作两个预制承台-桩连接构造试件和一个现浇承台-桩连接构造试件,进行往复加载试验与非线性数值分析。试验结果表明：与现浇承台试件相比,预制承台试件的屈服点、极限承载力基本相同,桩的抗裂性能、裂缝分布也基本一致;现浇承台更易开裂,但预制承台裂缝数量更多、最大裂缝宽度更大;桩-预制承台连接试件的初始刚度略小,但开裂后的刚度与现浇承台试件相同;两种承台均能与桩共同受力,整体性能够得到保证。数值模拟与试验的倾角-位移曲线和滞回曲线较好吻合,表明数值模型可反映试件的变形情况、承载力与捏缩特性。试验和数值分析均验证了预制承台-桩连接构造受力性能的可靠性。     

Effects of nanotube size and roof-layer coating on viscoelastic properties of hybrid diamond-like carbon and carbon nanotube composites

Hybrid carbon nanobuffers are developed by exploiting the ultra-hardness and wear-resistant properties of diamond-like carbon (DLC) coatings and the inherent viscoelasticity properties of vertically aligned carbon nanotubes (VACNTs). The viscoelastic properties of carbon nanobuffers incorporating thin-walled and thick-walled CNTs, respectively, are characterized by means of nanoindentation dynamic mechanical analysis tests. It is shown that the thin-walled nanobuffer has a better damping performance than the thick-walled nanobuffer due to its buckling-driven friction and post-buckling behaviors; particularly under large displacements. In addition, it is shown that under large indenter displacements, the VACNT arrays with DLC coatings display the improved stress distributions and enhanced strain energy dissipation performances due to the load transfer on the top of VACNTs. Molecular dynamics (MD) simulations are performed to investigate the roof-layer effect on damping behavior and structural deformation of the coated and uncoated VACNTs under nanoindentation. The results confirm that the VACNT with a DLC coating exhibits the significantly damping characterizations than the non-coated VACNT. Overall, the results presented in this study reveal the potential for tuning the damping performance of CNT-based nanobuffers through a careful control of the CNT size.     

曳引轮铁模覆砂铸造过程控制

介绍了曳引轮铁模覆砂的生产工艺，在试生产过程中通过采取针对性措施，消除了铸件夹砂、夹渣、变形等缺陷，产品合格率大幅度提高。     

基于热网络的中腰导轨移动式立柱热流强度的反求研究

以杭州机床集团有限公司生产的MKL7120数控成形磨床的中腰导轨移动式立柱为研究对象,根据立柱的结构特点构建立柱的热网络模型,通过实验测量立柱热稳态下特殊点处的温度值并结合所建的热网络模型反求出流入立柱的热流强度。利用仿真软件Multisim11,将反求结果作为已知的热流源代入所建立的热网络电路中,仿真得到热网络中所有节点的温度数据,并与实验数据进行对比,其误差小于2%,从而进一步验证了模型的正确性和合理性。利用该模型对主轴转速和磨头滑块移动速度进行了相关的特性分析,为进一步研究立柱瞬态温度场和热变形提供了重要的数据。     

中压单芯交联电缆护套松弛问题的解决措施

交联聚乙烯绝缘电缆在制造过程中,绝缘线芯放置时间不够,绝缘线芯中气体未充分释放出来,就直接进行下道工序会引起电缆外护套松弛。针对中压单芯交联聚乙烯绝缘电缆出现这种情况的原因进行了分析,并提出解决的措施。     

Improvement of corrosion resistance and electrical conductivity of 304 stainless steel using close field unbalanced magnetron sputtered carbon film

Carbon film has been deposited on 304 stainless steel (SS304) using close field unbalanced magnetron sputter ion plating (CFUBMSIP) to improve the corrosion resistance and electrical conductivity of SS304 acting as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The corrosion resistance, interfacial contact resistance (ICR), surface morphology and contact angle with water of the bare and carbon-coated SS304 are investigated. The carbon-coated SS304 shows good corrosion resistance in the simulated cathode and anode PEMFC environment. The ICR between the carbon-coated SS304 and the carbon paper is 8.28-2.59 mΩ cm² under compaction forces between 75 and 360 N cm⁻². The contact angle of the carbon-coated SS304 with water is 88.6°, which is beneficial to water management in the fuel cell stack. These results indicate that the carbon-coated SS304 exhibits high corrosion resistance, low ICR and hydrophobicity and is a promising candidate for bipolar plates.     

高压电力电缆阻水结构研究与分析

用试验的方法,对目前国内的高压交联聚乙烯(XLPE)绝缘电力电缆阻水结构进行了研究,分析了使用纵向阻水结构电缆的技术性能,并提出改善这种性能的工艺控制方法及建议。