填充银纳米线自修复型导电胶

采用乳液聚合法制备了壳为聚苯乙烯,核为分散有银纳米线的聚硫醇与二乙基苯胺(DMBA)的混合物的核壳结构纳米粒子.将这些纳米粒子分散在填充有银纳米线的各项同性导电胶(ICA)胶体中,在外界作用力下,这些纳米核壳结构粒子自动破裂,聚硫醇与DMBA的混合物与胶体中过量的环氧基团快速反应,自动修复受外力破坏产生的胶体微裂纹,同时核壳结构粒子中的银纳米线均匀分散在修复处,起到对导电网络的修复作用.研究了核壳结构粒子的填充量对导电胶力学及电学修复效果的影响.并对修复机理进行了阐述.     

基于非离子复合乳化剂自修复微胶囊的制备

提出采用低起泡性的OP-10/AEO非离子复合乳化体系解决微胶囊制备过程中乳化缺陷问题。以改性环氧树脂E-51为芯材修复剂,通过原位聚合法制备脲醛树脂自修复微胶囊。采用光学显微镜、傅里叶红外光谱仪、同步热分析仪分别对形成过程、化学结构及热稳定性进行分析。利用Gauss拟合研究粒径分布,并探讨了乳化剂体系选择、乳化剂用量、芯壁比、搅拌速率等因素对微胶囊性能的影响。结果表明,该体系能有效改善乳化剂起泡效果,用量为5.0%,芯壁比为0.8∶1,搅拌速率为1 200 r/min,微胶囊包封率达到80%,粒径分布相对集中,具备良好的室温贮存性及热稳定性。     

工程水泥基复合材料自愈合过程与产物

借助环境扫描电镜(ESEM)对纤维表面以及15,30,50μm不同宽度裂缝自愈合产物的生长过程进行了连续观察,结合EDS(energy dispersive spectroscopy)、TEM(transmission electron microscopy,透射电镜)、XRD(X-raydiffraction)及FTIR(fourier transform infrared spectroscopy)等先进研究手段,对工程水泥基复合材料(ECC)裂缝自愈合产物的化学特性进行了分析.结果表明,体系中水泥基材料的进一步水化及C-S-H凝胶和CaCO3晶体的生成是裂缝自愈合的主要原因.宽度15μm裂缝的自愈合产物主要为C-S-H凝胶;宽度30μm裂缝的自愈合产物主要为C-S-H凝胶和CaCO3;观察周期内,宽度50μm形成的自愈合产物量无法填满裂缝.从微观层次上看,宽度30μm以下的裂缝几乎都能完全自愈合.同时,ECC材料中的PVA(聚乙烯醇)纤维有亲水特性,为自愈合产物的形成提供了成核点,有助于ECC材料自愈合产物的形成和生长.     

密胺树脂包覆甲基丙烯酸正丁酯微胶囊的制备

以甲基丙烯酸正丁酯（BMA）为囊芯,密胺树脂为高分子囊壁材料,采用原位聚合法制备具有自修复功能的微胶囊.利用激光粒径分布仪、光学显微镜、微机差热天平和傅里叶变换红外光谱仪分别研究了微胶囊的粒径分布、表面形态、热性能和化学结构.讨论了乳化剂用量、搅拌速度以及芯材与壁材的投料质量比对微胶囊制备工艺的影响.结果表明：所得微胶...     

Phase analysis and thermal conductivity of in situ O′-sialon/β-Si3N4 composites

Typical O??-sialon-based ceramics, with a formula of Si_2?x Al _x O_1+x N_2?x , where x was set as 0.25, were fabricated by in-situ synthesis. Si₃N₄, Al₂O₃, and SiO₂ powders were used as raw materials, and MgO and Y₂O₃ were added as sintering additives. All the samples were sintered at different temperatures under a nitrogen pressure of 0.25?C0.30 MPa, and their microstructure, phase content, and thermal conductivity were evaluated. The effects of O??-sialon and ??-Si₃N₄ on the thermal conductivity were analyzed by numerical calculation in detail. In the case of the similar porosity, the thermal conductivity of O??-sialon-based ceramics decreased with the ratio of O??-sialon/??-Si₃N₄ increasing. When the ratio was 12, the thermal conductivity of O??-sialon ceramics sintered at 1360°C was 1.197 W·m^?1·K^?1.     

基于分子动力学的不同沥青分子自愈机制分析

对沥青材料自愈合机理的探究是评价沥青愈合潜力的关键因素之一,这对于预测沥青的疲劳寿命有着关键性作用。为了探究沥青材料的自愈合性能,本文基于分子动力学模拟,利用Materials Studio软件建立基质沥青、SBS改性沥青、老化沥青以及老化SBS改性沥青的三维微裂缝模型,并通过密度分析,相对浓度分布以及自由体积分数等方法,分析自愈合模型的愈合情况。结果表明,SBS改性剂对沥青的自愈有一定的促进作用,老化对沥青的自愈有一定的抑制作用,四种沥青的自愈潜力从大到小依次为SBS改性沥青、基质沥青、老化后SBS改性沥青以及老化沥青。     

修复-润滑双功能微胶囊/环氧树脂复合材料的摩擦学性能研究

以润滑剂（亚麻籽油、聚α烯烃或1-丁基-3-甲基咪唑六氟磷酸盐）和修复剂（邻苯二甲酸二丁酯）为芯材,脲醛树脂为壳材,采用原位聚合法合成了双芯材微胶囊,将微胶囊填充在环氧树脂中得到固体自润滑复合材料;使用扫描电子显微镜（SEM）、傅里叶变换红外光谱仪（FT-IR）、热重分析仪（TGA）对微胶囊进行了表征;使用摩擦磨损试验机、三维白光干涉仪、光学显微镜、扫描电子显微镜测试了微胶囊/环氧树脂复合材料的摩擦和修复性能。结果表明,微胶囊在整体上呈球形,结构完整,两种芯材均成功包覆;当加入质量分数为10%的微胶囊（芯材为亚麻籽油和邻苯二甲酸二丁酯）时,与环氧树脂相比,在摩擦试验测试1 200 s后自润滑复合材料的摩擦系数降低了约90%,在磨损试验测试2 h后其磨损体积减小约3个数量级（由10¹⁰ μm³减小到10⁷ μm³）;被划伤的复合材料经50℃加热1 h后,与加热前相比划痕变窄、变浅。以上结果表明,制备的双功能微胶囊/环氧树脂复合材料的耐摩擦磨损性能相对环氧树脂有所提高,同时具有良好的自修复特性,极大地提高了复合材料的综合使用性能。     

氧化石墨烯/微胶囊混凝土抗硫酸盐侵蚀性能研究

为解决西北地区输变电工程对于混凝土材料耐久性和导电性的特殊需求,以硅酸钠和膨润土作为囊芯、乙基纤维素作为囊壁,物理法合成微胶囊。外掺氧化后石墨烯充当导电介质,制备混凝土复合材料标准试件。随后对试样进行硫酸盐浸泡和干湿循环试验,分析了硫酸盐侵蚀后混凝土的表观特征、质量损失率和力学性能。结果表明:微胶囊的加入显著提高了抗硫酸盐性和自愈性,含有乙基纤维素包封的胶囊混凝土表现出良好的抗硫酸盐性和自愈性。     

Theoretical study on stereodynamics of H + NeH+ (v = 0, j = 0) → H2 + + Ne reaction

Stereodynamics of reaction H + NeH+(v = 0,j = 0) → H2+ + Ne is investigated by quasi-classical trajectory method using a new potential energy surface constructed by Lv et al.The distributions of P(r),P(r) and PDDCSs are calculated at four different collision energies.The rotational polarization of product H2+ presents different characters at different collision energies.The product rotational angular momentum vector j’ is not only aligned,but also oriented along the direction perpendicular to the scattering plane.With the increase of collision energy,the rotation of product molecule has a preference of changing from the "in-plane" mechanism to the "out-of-plane" mechanism.Although the title reaction is mainly dominated by the direct reaction mechanism,the indirect mechanism plays a role when the collision energies are low.     

纳米材料/环氧复合涂层的耐蚀性能研究进展

结构保护法、保护层法、防护层材料法、电化学保护法和介质处理法等是金属防腐蚀的主要方法,在诸多缓蚀方法中,防护层材料法是一种经济高效且广泛使用的防腐方法。环氧树脂是一种高效的防护层材料,需经过常温固化或加热固化后使用。然而,其固化过程存在的微孔会弱化环氧涂层的耐蚀性。将纳米材料加入环氧树脂中形成环氧树脂复合涂层,可填补环氧涂层中的微孔,提升环氧涂层的防腐效率。首先,详细讨论了影响纳米材料/环氧复合涂层耐蚀性能的因素,探讨了纳米材料/环氧复合涂层的防腐机理。其次,简要介绍了用于环氧涂层的2种纳米材料（石墨烯和金属有机框架材料）,总结了石墨烯和金属有机框架材料的改性和修饰方法。最后,从树脂成分、填料成分、机理探究以及开发自愈合涂层等方面对纳米材料/环氧复合涂层应用存在的问题和发展前景进行了展望,提出纳米材料/环氧复合涂层是一种长期防护金属免受腐蚀的方法,未来应致力于研发用于环氧涂层的二维和三维材料。     

一种快速自修复磁性聚合物高分子

通过简单的方法合成了一种兼具柔韧性和拉伸性的室温快速自修复磁性聚合物高分子。基于单分子磁体Mn₁₂-Ac和含有脲键的聚二甲基硅氧烷高分子基底之间的氢键作用,该复合物材料展现了出色的磁性和室温快速自修复性质（修复时间为60 s,修复效率为99.5%）。这项工作将为磁性自修复材料在未来智能器件、响应型机器人等领域的应用提供更多的机会。     

Tailoring impedance match and enhancing microwave absorption of Fe3O4/ Bi24Fe2O39/Bi hollow porous microrods by controlling their composition

A self-assembly/precipitate conversion/decomposition process was developed for the controllable synthesis of Fe_3O_4/Bi_(24)Fe_2O_(39)/Bi hollow porous microrods(HPMRs).The results demonstrated that the crystal size,component,and performances of HPMRs could be effectively modulated via changing Fe~(2+)/Bi~(3+)molar ratio(γ).Fe_3O_4/Bi_(24)Fe_2O_(39)/Bi HPMRs exhibited ferromagnetic behavior at room temperature.As Bi and Bi_(24)Fe_2O_(39)contents increased withγ,the saturation magnetization M_sand attenuation constantly decreased,whereas coercivity H_cand impedance matching ratio increased.Compounding Fe_3O_4with small quantities of Bi and Bi_(24)Fe_2O_(39)into HPMRs can significantly enhance microwave absorption.Fe_3O_4/Bi_(24)Fe_2O_(39)/Bi HPMRs formed atγ=1:0.25 exhibited the optimum microwave absorption performance.The minimum R_Lwas-47.3 dB at8.72 GHz,corresponding to 2.4 mm sample thickness.The absorption band with the reflection loss below-20 dB was up to 14.0 GHz for the absorber with a thickness of 1.4-8.0 mm.The results demonstrate that the introduction of electromagnetic transparent materials(Bi_(24)Fe_2O_(39)or Bi)can improve the microwave absorption performances of Fe_3O_4 composites owing to enhanced impedance matching rather than attenuation constant.     

聚脲甲醛-生物油微胶囊的研制及性能探究

为研究微胶囊对沥青路面微裂纹的愈合效果,首先利用聚脲甲醛(作为微胶囊壁)和生物油(作为微胶囊心)采用原位聚合法制备微胶囊,采用扫描/透射电子显微镜(SEM/TEM)和热重分析(TGA)探究微胶囊的外观形貌和热稳定性;然后将微胶囊用于制备微胶囊/苯乙烯-丁二烯-苯乙烯(Microcapsule/SBS)复合改性沥青,通过动态剪切流变仪(DSR)和离析试验探究微胶囊的掺加对复合改性沥青路面性能的影响;最后通过延度愈合率试验验证微胶囊的愈合效果,并结合宏微观试验分析其愈合机理。结果表明：微胶囊呈现类球状,且表面较为粗糙,增大了与沥青的接触面积。微胶囊的热稳定性较好,其囊壁可承受沥青混合料生产过程中的高温环境。随着微胶囊的添加,复合改性沥青的低温塑性和耐热性均有所改善。此外,复合改性沥青的储能模量和损失模量也有所提升,即微胶囊的添加提升了SBS改性沥青的黏弹性能,这可能是由于添加的微胶囊与SBS和基质沥青具有很好的相容性,且微胶囊均匀分散在沥青内部并嵌入SBS呈现的网状结构中,这也在离析试验和荧光显微试验中得以证实。当微胶囊的掺量为0.4%时,复合改性沥青的愈合率达到最高。     

Morphological evolution and kinetic enhancement of Li2FexMn1-xSiO4/C cathodes for Li-ion battery

Li_2MnSiO_4-based cathode materials possess reasonable work potentials and high theoretical capacities,while the practical energy/power densities are constrained by their inferior kinetics of Li~+ diffusion.In this work,the Pmn2_1-structure Li_2Fe_xMn_(1-x)SiO_4/C materials were synthesized via a solvothermal method and evaluated as Liion cathode materials,with notable morphological evolutions and tunable crystallographic habits observed after solvothermal process.The Li_2Fe_(0.33)Mn_(0.67)SiO_4/C material delivers an initial reversible capacity of 250.2mAh g~(-1)at 0.1 C(～1.51 Li~+insertion/extraction,1 C=166 mA g~(-1)),excellent high-rate capability(52.2 mAh g~(-1)at 5 C),and good long-term cyclability(64.6%after 196 cycles at 2 C).The enhanced electrochemical properties are attributed to the boosted ion/electron transports induced by preferred morphological and structural characteristics of Li_2Fe_(0.33)Mn_(0.67)SiO_4/C.     

深海石油钻采隔水管浮力材料的制备及其强度分析

隔水管系统是海洋石油钻采的重要技术装备,而浮力块是深水条件下钻井隔水管系统的必备部件。笔者使用碳纤维增强聚合物中空球,与环氧树脂、空心玻璃微珠以适当比例混合,采用真空浇注工艺制备3组分隔水管浮力材料,并采用有限元软件ANSYS对浮力块在不同的工况下进行强度分析。研究结果表明,浮力材料密度为500kg/m~3,压缩强度为60 MPa;浮力块最大变形发生在其自由端,其值为4.08mm;最大应力发生在与隔水管相邻的结构上,其值为50.02MPa。最大变形值和应力值均很小,所制备的隔水管浮力块强度满足3 000m水深以内钻采作业要求。     

Low concentrations of NaHSO3 enhance NAD(P)H dehydrogenase-dependent cyclic photophosphorylation and alleviate the oxidative damage to improve photosynthesis in tobacco

Bisulfite at low concentrations(L-NaHSO3) increases cyclic electron transport around photosystem I(PSI) and photosynthesis.However,little is known regarding the detailed contribution of cyclic electron transport to the promoted photosynthesis by L-NaHSO3.In the present work,we used tobacco mutant defective in ndhC-ndhK-ndhJ(ndhCKJ) to investigate the role of NAD(P)H dehydrogenase(NDH)-dependent cyclic electron transport around PSI in an increase in photosynthesis by L-NaHSO3.After the treatment of tobacco leaves with L-NaHSO3(10 μmol L-1),the NDH-dependent cyclic electron transport,monitored by a transient post-illumination increase in Chl fluorescence and the amount of NDH,was notably up-regulated in wild type(WT).The NDH-dependent cyclic electron transport was severely impaired in ndhCKJ and was not significantly affected by treatment with L-NaHSO3.Accordingly,the NDH-dependent transthylakoid membrane proton gradient(pH),as reflected by the slow phase of millisecond-delayed light emission(ms-DLE),was increased by L-NaHSO3 in WT,but not in ndhCKJ;the enhancement of cyclic photophosphorylation(PSP) activity by L-NaHSO3 was more obvious in WT than ndhCKJ.The accumulation of both superoxide and hydrogen peroxide was reduced in WT when subjected to L-NaHSO3 treatment,but not in ndhCKJ.Furthermore,the increase of photosynthetic O 2 evolution rate by L-NaHSO3 was more significant in WT than in ndhCKJ.We therefore conclude that L-NaHSO3 alleviates the photo-oxidative damage by the enhancement of NDH-dependent cyclic PSP,thereby improving photosynthesis.     

基于微生物的水泥基材料裂缝自修复技术研究进展

 微生物自修复水泥基材料裂缝因具有较大的修复潜力和环境友好等特点而受到广泛关注。从微生物自修复水泥基材料裂缝发展历程、微生物诱导矿化沉淀结晶机理、微生物诱导矿化产率及影响因素、微生物的固载及固载后矿化活性的测定、裂缝制作方法及修复养护条件、修复效果表征方法、裂缝自修复效果和微生物自修复剂对水泥基材料自身性能的影响方面,综述了其研究进展,并指出了目前微生物自修复水泥基材料研究中主要存在的问题。     

Distribution,ecology, and oxygen and carbon isotope characteristics of modern planktonic foraminifers in the Makarov Basin of the Arctic Ocean

The Arctic region, with magnificent ice cover on the surface of the Arctic Ocean and adjacent seas, is not only extremely sensitive to but also has strong amplification effects on climate change. Observations during the past decades have documented substantial retreat and thinning of the Arctic sea-ice cover, a process that is accelerating. Its feedback and impact on the global climate has become an important subject of current climate change research. Calcite tests of planktonic foraminifers are major constituents in pelagic sediments, and they provide valuable materials for the reconstruction of past oceanographic conditions. However, research is still sparse in the Arctic sea area because of limited availability of the materials for investigation. Here, we present a study of modern foraminifers from the plankton tow samples taken in the Makarov Basin of the Arctic Ocean during the fourth Arctic expedition of China. We have analyzed ecological information stored in the modern planktonic foraminifers and in their stable isotope signals, and established a relationship between the distribution of the main taxa and the environment. Our main observations are as follows:(1) in the Makarov Basin, the polar species Neogloboquadrina pachyderma(sinistral coiling) dominates the [150 lm planktonic foraminiferal assemblages.(2) The planktonic foraminifers live mainly in the upper halocline at a water depth of 50–100 m and less in the depth interval of 100–200 m.(3) Temperature change in the halocline can affect the absolute abundance of planktonic foraminifers and their distribution in the water column. The warmer halocline is more favorable to the development of planktonic foraminifers.(4) A lighter d18O value(2.11 %) of N. pachyderma(sin.) is recorded in the depth interval of 100–200 m, which is likely related to the isotopically light brines separated out during sea ice freezing. The relatively heavy d18O value(1.68 %–2.68 %, average 2.27 %) in the depth interval of 50–100 m may be influenced by the low salinity water with the relatively heavy d18O value formed during the sea-ice melting in the surface layer.     

自修复混凝土中胶黏剂性能的试验研究

自修复混凝土具有优越的智能性和安全性,对其基础理论进行研究意义重大。而胶黏剂作为自修复混凝土的一种修复材料,对混凝土的自修复效果起着决定性的作用。因此为了保证修复后的混凝土裂缝不再开裂,胶黏剂必须具有良好的流动性和较高的黏结强度。以WD5319、长城717胶黏剂和环氧树脂三种胶黏剂为例,分别进行流动性与黏结强度试验;对试验数据进行分析比较后选出综合性能最佳的胶黏剂。结果表明:自制的流动性试验装置能够比较真实的反映胶黏剂在混凝土裂缝中的流动情况,即混凝土微裂缝宽度越大,胶黏剂流速越快;当其他条件一定时,流速由快到慢依次为:WD5319、长城717胶黏剂和环氧树脂;黏结界面黏附面积越大,固化龄期越长,胶黏剂黏结强度越大;且当其他条件一定时,黏结强度由高到低依次为:环氧树脂、长城717胶黏剂和WD5319。     

鸡腿菇多糖微胶囊的制备工艺研究

在单因素试验基础上,以微胶囊包埋率为考察指标,采用U10（53）进行均匀试验设计,对鸡腿菇多糖微胶囊的制备工艺进行优化。试验结果通过二次多项式逐步回归分析,对鸡腿菇多糖微胶囊包埋率影响最大的因素是鸡腿菇多糖的质量分数,制备工艺优化方案为：壳聚糖的质量分数为1.6%,海藻酸钠的质量分数为2.2%,鸡腿菇多糖的质量分数为2.0%。应用优化得到的制备工艺进行验证试验,并将得到的微胶囊进行结构表征,表明微胶囊包埋率较高,成型性良好,热稳定性能得到改善。