Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles

Optimization methods are presented to design Halbach arrays to maximize the forces applied on magnetic nanoparticles at deep tissue locations. In magnetic drug targeting, where magnets are used to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces with distances from magnets has limited the depth of targeting. Creating stronger forces at a depth by optimally designed Halbach arrays would allow treatment of a wider class of patients, e.g. patients with deeper tumors. The presented optimization methods are based on semi-definite quadratic programming, yield provably globally optimal Halbach designs in 2 and 3-dimensions, for maximal pull or push magnetic forces (stronger pull forces can collect nanoparticles against blood forces in deeper vessels; push forces can be used to inject particles into precise locations, e.g. into the inner ear). These Halbach designs, here tested in simulations of Maxwell's equations, significantly outperform benchmark magnets of the same size and strength. For example, a 3-dimensional 36 element 2000 cm³ volume optimal Halbach design yields a 5× greater force at a 10 cm depth compared to a uniformly magnetized magnet of the same size and strength. The designed arrays should be feasible to construct, as they have a similar strength (≤1 T), size (≤2000 cm³), and number of elements (≤36) as previously demonstrated arrays, and retain good performance for reasonable manufacturing errors (element magnetization direction errors ≤5°), thus yielding practical designs to improve magnetic drug targeting treatment depths.     

金属有机物化学气相法制备YBCO超导薄膜研究

运用金属有机物化学气相沉积法(MOCVD),在LaAlO3(LAO)单晶上沉积YBa2Cu3O7-x(YBCO)超导薄膜。通过使用优化的进液装置,使金属有机源连续、稳定地输送至蒸发皿进行闪蒸。通过优化总气压、氧分压等生长条件,获得高质量的YBCO薄膜。在固定的温度条件下,调节反应总气压和氧分压,在总压为380Pa,氧分压为180Pa获得YBCO薄膜临界电流密度Jc=0.6MA/cm2。随着氧分压增大,YBCO薄膜产生a轴取向,(005)峰向左偏移,且薄膜中的Cu/Ba由1.0变化至1.63。在Cu/Ba=1.48时,YBCO薄膜结构与性能较优。     

pH药物控释的氮掺杂碳点载运阿霉素用于光热与化疗的协同治疗

提出一种利用氮掺杂碳点(N-CDs)的光热性能与化疗药物阿霉素(Dox)相结合的联合治疗肿瘤模式。实验结果标明,所制备的N-CDs的分散液经光照后升温可达10℃,是性能优异的光热剂。同时,载运Dox后的N-CDs-Dox纳米复合物还具有pH触发的药物控释作用。因此,这种多功能的N-CDs-Dox纳米复合物能够实现光热和化疗的协同作用,有效杀伤肿瘤细胞。     

卷烟烟气总粒相物中氟节胺含量的检测方法

建立了气相色谱电子捕获器法检测卷烟抽吸过程中氟节胺向主流烟气总粒相物中转移量的方法,卷烟在标准条件下抽吸,用剑桥滤片捕集主流烟气总粒相物,经乙腈提取、石墨碳黑固相萃取柱或自制混合层析柱净化、GC/ECD检测后,外标法定量.氟节胺在0.02 ～20 mg/L范围内线性关系良好,检出限为9.14×10-6 g/L.加标量为...