快速膜乳化与热固化法制备粒径均一的pH敏感壳聚糖季铵盐凝胶微球

以具有升温自固化特性的壳聚糖季铵盐/甘油磷酸钠混合溶液为水相,利用快速膜乳化与热固化法制备了粒径均一、pH敏感的壳聚糖季铵盐凝胶微球,考察了跨膜压力、水油相组成、水油相体积比及微孔膜孔径等对微球粒径、结构和药物包埋率的影响. 结果表明,得到粒径698±57.33, 1145±71.48, 2021±53.63及3984±191.72 nm、粒径分布窄(多分散系数<0.1)、药物包埋率高达75.49%±2.62%的凝胶微球. 所制微球生物相容性好,有明显的pH敏感性,中性和碱性环境下结构稳定,药物缓释,pH=7.4时24 h内药物累计释放率为34.6%;酸性环境下微球崩解,药物快速释放,pH=5.5时1 h内药物累计释放率高达79.6%

Structural optimization of Fe-n-Pt-m ( 5 <= n + m <= 24) alloy clusters based on an improved Basin-Hopping Monte Carlo algorithm

合金纳米团簇可以充分利用多种金属的协同效应来实现材料的多功能特性,因而备受关注.本文利用改进的Basin-Hopping Monte; Carlo算法研究了不同尺寸和不同比例下的Fe-Pt二元合金团簇的结构稳定性.为证明初始结构相关性,引入了相似函数来分析合金团簇稳定结构与其对应; 的单金属团簇结构之间的相似性,并分析了Fe-Pt合金团簇在稳定结构下的元素分布.研究结果表明:对于N ≤; 24的Fe-Pt合金团簇,其结构并没有随原子数的增长呈现出明显的形状变化.但是就原子分布而言,对于相同尺寸下不同比例的原子结构,Fe元素趋向于分; 布在外层,而Pt元素更趋向于分布在内层;对于相同比例不同尺寸的原子结构也得到了同样的结论,并且在Fe原子比例越大的情况下,这种趋向的分布越明显.; 此外,通过计算合金团簇与单一金属团簇的结构相似函数,发现N≤; 24的Fe-Pt合金团簇在吸收Fe单金属和Pt单金属基态结构的基础上,随着元素比例的变化,发生了不同于单金属基态结构的变化,并且不同比例结构差异; 较大.最后,通过计算Fe-Pt合金团簇能量的二阶有限差分值,在Fe-Pt表现出分离结构状态时找到了相对稳定度最好的稳定结构.Alloy nanoclusters have received extensive attention because they can achieve bifunctional properties by making good use of the cooperative effect of two metals. In this paper, an improved Basin-Hopping Monte Carlo (BHMC) algorithm is proposed to investigate the structural stabilities of Fe-Pt alloy nanoclusters. Different cluster sizes and chemical compositions are considered. Moreover, a similarity function is introduced to analyze the structural similarity between the stable structures of alloy clusters and those of their monometallic clusters. Meanwhile, the atomic distributions of Fe-Pt alloy clusters are considered for their stable structures. The results indicate that for Fe-Pt alloy clusters with the size N <= 24, there is no significant structural evolution with the increase of cluster size. Fe atoms prefer to segregate at the peripheral positions of the clusters, while Pt atoms tend to occupy the interior. The same distribution result can be obtained for the structures of clusters with different compositions. With Fe composition increasing, this distribution trend is more pronounced for the Fe-Pt alloy clusters.; In addition, by calculating the structural similarity function between alloy and monometallic clusters, we find that the stable structures of Fe-Pt alloy clusters gradually vary with composition ratio. Moreover, when the Fe atoms or Pt atoms are added into the Fe-Pt alloy system, they change the stable structures of Fe-Pt alloy clusters, resulting in a different structure from Fe and Pt monometallic ones. Also, the structural similarity is different when the Fe composition varies. Furthermore, the best stable structures of Fe-Pt clusters with different compositions and sizes are obtained by calculating the second-order finite difference in energy of Fe-Pt alloy clusters.National Natural Science Foundation of China [11474234, 51271156,; 61403318]; Fundamental Research Fund for the Central Universities, China; [20720160085

Functional connectivity of the fronto-striatal circuitry in patients with bulimia nervosa based on resting-state fMRI

目的通过fMRI技术,探讨神经性贪食(bulimia nervosa,BN)患者静息态下额叶-纹状体环路的功能连接特点及其与抑制功能的相关性.方法对27例未用药的成年女性神经性贪食患者及27名性别、年龄、受教育年限与患者组匹配的健康对照被试进行信号停止任务(stop signal task,SST)测试;并行静息态fMRI扫描,分析比较两组纹状体功能亚区与额叶脑区间的功能连接差异.结果与对照组相比,BN组右侧腹头侧壳核(ventral rostral putamen,VRP)与右侧辅助运动区(supplementary motor areas,SMA)及运动前区(Premotor area,PM)间的功能连接减弱(MNI坐标:x=3,y=-15,z=51,K=27;MNI坐标:x=27,y=0,z=57,K=44);双侧背尾侧壳核(dorsal caudal putamen,DCP)(MNI坐标:x=21,y=-6,z=48,K=43)与右侧PM(MNI坐标:x=21,y=-12,z=57,K=24)间的功能连接减弱(P<0.05,Alphasim校正,voxel P<0.005,体素簇≥20个体素).BN组右侧VRP与右侧SMA的功能连接强度与停止信号反应时间(stop signal reaction time,SSRT)呈负相关(r=-0.595,P=0.004);右侧DCP与右侧PM间功能连接强度与冲动性调节评分(进食障碍调查量表-II)呈正相关(r=0.483,P=0.023).结论未用药成年女性神经性贪食患者存在静息态下额叶运动皮层与纹状体间的功能连接异常,该功能连接异常与BN患者的抑制功能受损有关

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies