一类具密度制约SIS模型的全局稳定性和周期性

研究了一类具密度制约和双线性传染率的S IS传染病模型,考虑到了实际中对易感者和传染者的控制,得到了地方病平衡点的全局渐近稳定性和系统的周期性,并给出了生物学解释和仿真.     

高导热环氧模塑料的制备

介绍了导热系数大于3 W/(m·K)高导热环氧模塑料的制备。以低黏度多芳香环（MAR）环氧树脂和MAR酚醛树脂为基体,以偶联剂处理的球形氧化铝做导热填料,磷类做催化剂,经高速混合机混合、双螺杆挤出机挤出,合成高导热环氧模塑料。并研究了不同偶联剂类型对弯曲强度的影响。通过改变填充量至93%,导热系数最高可达5.6 W/(m·K),且有较好的弯曲性能和流动性能。     

磺酰基亚胺类给电子体聚丙烯催化剂的性能

以N-(3-氯苯)-二(三氟甲基磺酰基)亚胺为内给电子体的聚丙烯催化剂具有较好的氢调敏感性,随着加氢量的增加,聚丙烯的熔融指数较大幅度地增加。丙烯共聚实验表明,该催化剂还具有较好的丙烯共聚性能。用升温梯度淋洗分级(TREF)的方法对样品进行分级处理的结果表明,所生成的共聚聚丙烯样品与对比样品SP179(市场上的共聚聚丙烯牌号)具有十分相似的TREF分级图。宏观力学性能测试表明,所得共聚聚丙烯非常符合工业上作为汽车保险杠专用树脂的使用要求。     

论扫描声学显微镜在电子封装中的应用

探讨了在使用扫描声学显微镜对IC封装体扫描时,对扫描图形中的黑点产生的原因及判定方法以及芯片底部芯片胶分层的波形情况及其扫描方法进行了讨论,结果表明,气孔和未分散的橡胶是造成扫描图中黑点的原因,芯片胶底部的分层需要由透射图形结合波形图才能准确判定。     

Modification of Polylactic Acid by Reactive Blending with Functionalized Imidazolium-based Ionomers and Epoxy-containing Additives北大核心CSCD

Aiming to tackle the serious brittleness problem of polylactic acid（PLA）,PLA-based multiphase blends are prepared by melting reactive blending with hydroxyl functionalized ionomer as the toughening agent and compatibilizer containing epoxy groups. The structures and properties of the blends are characterized by scanning electron microscopy（SEM）,Fourier transform infrared spectrometer（FT-IR）,differential scanning calorimetry（DSC）and mechanical properties tests. The synergistic compatibilization and toughening effects of epoxy soybean oil （ESO）,polyethylene glycol diglycidyl ether （PEGDE）and ethylene-methyl acrylate-glycidyl methacrylate （AX8900） terpolymer are compared and analyzed. The results show that the compatibilization effect is closely related to the content and position of the epoxy group in the additives,which presenting different toughening effects. The addition of AX8900 can effectively improve the toughness of the blend system to obtain balanced mechanical properties. However,ESO tends to lead to crosslinking,which limits the toughening efficiency. PEGDE mainly shows a plasticizing effect,leading to the reduction of tensile strength. The results demonstrate modification of the PLA blends by reactive blending with different epoxy additives and hydroxy-containing polymers is an effective strategy for the development of high-performance biobased PLA materials. © 2022, Science Press (China). All rights reserved.     

硅微粉对环氧塑封料的影响

介绍了环氧塑封料的组分和硅微粉对环氧塑封料性能的影响,研究了不同类型硅微粉及其不同配比对环氧塑封料的胶化时间、流动长度、DMA高温模量和冲击强度的影响。结果表明,在相同填料含量条件下,球形硅微粉的使用量增加,环氧塑封料具有较好的流动长度,随着结晶硅微粉加入量的增加,塑封料的熔融黏度随之增加,流动长度急剧下降,对集成电路的金引线的影响较为明显,严重影响了集成电路的可靠性;但含球形硅微粉的环氧塑封料具有较低的热膨胀系数、良好的流动性能和较高的冲击强度。     

Spectra of spontaneous Raman scattering in taper-drawn micro/nano-fibers

We study the spontaneous Raman scattering(RS) in taper-drawn micro/nano-fibers(MNFs) by employing the photon counting technique. The spectra of RS in five MNFs, which are fabricated by using different heating flames(hydrogen flame or butane flame) and with different diameters, are measured within a frequency shift range of 1435 cm~(-1)–3200 cm~(-1).From the measured spectra, we observe the RS peaks originated from silica and a unique RS peak with a frequency shift of ~ 2905 cm~(-1)(~ 87.2 THz). Unlike the former ones, the latter one is not observable in conventional optical fibers.Furthermore, the unique peak becomes obvious and starts to rapidly increase with the decrease of the diameter of MNFs when the diameter is smaller than 2 μm, and the intensity of the unique peak significantly depends on the heating flame used in the fabricating process. Our investigation is useful for the entanglement generation or optical sensing using taper-drawn MNFs.     

基于锁核酸的高选择性新型分子信标

通过在分子信标的错配位点修饰锁核酸, 不仅可有效地改善其单碱基错配识别能力, 还可提高检测灵敏度. 因而有望发展成为一种通用的提高分子信标单碱基错配识别能力的方法.     

利用自发四波混频测量光子晶体光纤色散

使用脉宽为1.6ps的脉冲光抽运0.6m长的光子晶体光纤,测量由光纤中自发四波混频过程所产生光子对的频谱,并利用所获得的相位匹配数据确定了待测光纤的色散。当抽运光的中心波长以1nm的步长,在1037～1047nm的范围内变化时,通过可调谐滤波器和单光子探测器测量光子晶体光纤产生的信号和闲频光子对的频谱,从而获得11组四波混频相位匹配数据。然后使用阶跃有效折射率模型对所获得的相位匹配数据进行拟合,得出待测光子晶体光纤的纤芯半径和包层空气比的有效值分别为0.949μm和29.52%,并在此基础上计算了光纤的色散及全频谱范围内的四波混频相位匹配曲线。实验结果显示,曲线预测值与实测值之间误差小于0.1%。