Targeted,Needle‐Free Vaccinations in Skin using Multilayered,Densely‐Packed Dissolving Microprojection Arrays

Targeting of vaccines to abundant immune cell populations within our outer thin skin layers using miniaturized devices—much thinner than a needle and syringe, could improve the efficacy of vaccines (and other immunotherapies). To meet this goal, a densely packed dissolving microprojection array (dissolving Nanopatch) is designed, achieving functional miniaturization by 1) formulating small microneedles (two orders of magnitude smaller than a standard needle and syringe) and 2) multiple layering of the payload within microprojections with tight tolerances (of the order of a micrometer). The formulation method is suitable to many vaccines because it is without harsh or complex chemical processes, and it is performed at low temperatures and at a neutral pH. When the formulated dNPs are applied to skin, consistent and robust penetration is achieved, rapidly targeting the skin strata of interest (<5 min; significantly faster than larger dissolving microneedles that have been previously reported). Resultant diffusion is significantly enhanced within the dermis compared with the epidermis. Using two different antigens (ovalbumin and a commercial trivalent influenza vaccine [Fluvax2008]), the administration of these dissolving patches generate robust systemic immune responses in a mouse model. To the authors' knowledge, this is the first report of successful vaccination with any form of dissolving microneedles. The patches made by this method therefore have the potential for pain‐free, needle‐free, and effective vaccination in humans.     

AZ80镁合金管材热挤压工艺及组织性能研究

选用不同的工艺参数对变形镁合金AZ80进行管材热挤压工艺实验研究;对挤压前后材料组织与力学性能的变化进行分析。研究结果表明：热挤压可以显著细化AZ80镁合金的晶粒,而且随着挤压比的增加,晶粒变得更加细小;增大挤压比也可以提高AZ80镁合金的抗拉强度和屈服强度。挤压比为18.2,坯料温度为390℃,模具预热温度360℃,凹模的半模角为60°～70°,可得到均匀的合金组织和良好的力学性能.     

Microstructures, mechanical properties and compressive creep behaviors of as-cast Mg-5%Sn-（0-1 .0）%Pb alloys

The microstructures, tensile properties and compressive creep behaviors of Mg-5%Sn-(0–1.0)%Pb (mass fraction) alloys were studied. The microstructures of the Mg-Sn-Pb alloys consist of dendritic α-Mg and Mg₂Sn phase. The addition of Pb can refine the size of Mg₂Sn phase and grain size, reduce the amount of Mg₂Sn phase at grain or inter-dendrite boundaries and change the distribution of Mg₂Sn phase. Pb exists in the Mg₂Sn phase or dissolves in α-Mg matrix. The mechanical properties of the tested alloys at room temperature are improved with the addition of Pb. When the Pb content is over 0.5%, the mechanical properties are decreased gradually. The Mg-5%Sn-0.5%Pb shows the best ultimate tensile strength and elongation, 174 MPa and 14.3%, respectively. However, the compressive creep resistance of the Mg-Sn-Pb alloys is much lower than that of the Mg-Sn binary alloy at 175 °C with applied load of 55 MPa, which means that Pb has negative effects on the compressive creep resistance of the as-cast Mg-Sn alloys.     

内氧化法制备AgCuONiO电接触材料的热力学分析及其组织演变

采用内氧化法制备了AgCuONiO电接触材料,理论推导了AgCuNi合金发生内氧化的热力学条件,利用光学显微镜、扫描电镜、电子拉力试验机等分析手段对其物理性能和微观结构进行了研究。结果表明:AgCuNi合金内氧化在热力学上是可行的,热力学区位图中择优氧化区的范围由上、下限氧分压共同确定。随着内氧化温度的提高,材料基体中的氧化物颗粒的尺寸有所增加,氧化物颗粒形貌由弥散颗粒状逐渐向链珠状过渡。试样的导电率、显微硬度以及抗拉强度也随内氧化温度的升高而逐步增加,基体中细小弥散的氧化物颗粒的析出是材料力学性能改善的根本原因。     

球形Ni(OH)2的微结构与电化学性能的关系

利用扫描电子显微镜(SEM)和X射线衍射(XRD)技术研究了球形Ni(OH)2的微结构特征,并利用统计方法讨论了微结构与电性能的关系。研究表明,球形Ni(OH)2的片层状、纺锤状表面微观形貌反映出比粒状表面更好的结晶程度和更大的晶粒度,并具有相对更高的放电容量,而球粒内部皆为放射状组合的片状结构;球形Ni(OH)2的放电比容量与其晶格常数c、(101)面衍射峰半高宽FWHM101有一定的正相关性,而与(001)面半高宽FWHM001有明显的负相关性,这说明〈001〉方向的晶粒度越大,放电比容量越大,与表面形貌对放电容量的影响规律相一致。     

B含量对Nd2Fe14B/Fe3B复合永磁材料微观结构和磁性能的影响

用熔淬法制备非晶带、再进行晶化处理,制备了纳米晶复合Nd4.5Fe77+xB18.5-x (x=0.1, 0.2, 0.3, 0.4)永磁磁粉,然后以环氧树脂为粘结剂制备粘结磁体.研究了B含量对材料磁性能和微观结构的影响.结果表明,随着B含量的提高,Nd4.5Fe77+xB18.5-x 粘结磁体的剩磁、矫顽力和磁能积都先增大后减小.适量的B可以细化复合材料的晶粒,改善微观结构,提高磁体磁性能;B含量过高使复合材料的晶粒长大,出现Nd1.1Fe4B4富B相,导致磁体磁性能下降.当B含量为18.3at%时,粘结Nd4.5Fe77.2B18.3磁体具有最佳磁性能:Br=0.88 T,Hcj=257kA/m,(BH)m=57kJ/m3.     

Influence of Y and Mn alternately doped order on the microstructures and dielectric properties of Ba0.6Sr0.4TiO3 films

ABSTRACT

The influences of Y and Mn alternately doped order on the microstructures and dielectric properties of the Ba_0.6Sr_0.4TiO₃ (BST) films were reported in this paper. The Y and Mn alternately doped BST films were designed as YBST/MnBST/… and MnBST/YBST…multilayer films orderly expressed as (Y/Mn)_M and (Mn/Y)_M for short, and prepared on Pt/Ti/SiO₂/Si wafers by an improved sol-gel method, where Y and Mn represent yttrium doped BST layer and manganese doped BST layer, and M is cycle unit, respectively. The microstructures of the alternately doped BST films were observed by SEM and the capacitance-voltage curves at 100 kHz or 1 MHz were measured by a HP4284A LCR meter and the dielectric properties in the range of 1GHz were measured by an E4991A impedance analyzer. Compared to Y or Mn doped multilayer BST film, (Y/Mn)_M and (Mn/Y)_M show higher dielectric tunability and lower dielectric loss with higher dielectric constant. Moreover, (Y/Mn)_M show better dielectric properties than (Mn/Y)_M because (Y/Mn)_M show granular microstructures independent of M, while the (Mn/Y)_M show granular microstructures when M is 2 and add to a surface layer of columnar microstructures on the granular microstructures when M is 4. The related mechanisms were obtained in terms of the XRD phase structures, the cross-sectional SEM microstructures and the AFM morphologies.