Hypoxia/Temperature/pH Triple Stimuli–Responsive Block Copolymers: Synthesis,Self-Assembly,and Controlled Drug Release

The amphiphilic block copolymer poly(methacrylic acid-co-2-nitroimidazole acrylate)-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (P(MAA-co-NIMA)-b-PDMAEMA) with the hypoxia/temperature/pH triple responsiveness is synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT), hydrolysis, and 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide (EDC) reactions, and successfully self-assembled into micelles. The hypoxia response in vitro is realized, and then the sensitivity of the self-assembled micelles to the hypoxia condition is studied by controlling the grafting amount of aminated 2-nitroimidazole. Because 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA) is a typical material sensitive to temperature and pH conditions, the self-assembled micelles are also responsive to temperature and different acidic/basic conditions. In addition, the cumulative release rate of doxorubicin (DOX) at 42 °C, pH = 6.0, and hypoxic conditions increases significantly, and verifies the synergistic promotion effect of the above stimulations. This intelligent polymer with triple response mechanism improves the controllability and efficiency of drug release, and is expected to be a drug carrier for cancer treatment.     

无刷电机驱动器在大型医疗设备上的应用

无刷电机及其驱动器在大型医疗上的设备应用越来越广泛。为了设计更好的医疗设备、造福患者,研发人员需要对驱动器有更深的理解和更好的选型及应用。需要理解无刷电机及驱动器的工作原理,清楚大型医疗设备对无刷电机驱动器的要求和实现方式,如安全性、可靠性、通讯等。在医疗设备开发中,驱动器的应用有多种方案,它们各具特点,包括通用驱动器,板载驱动器、自主研发驱动器。随着技术的发展,无刷电机驱动器在大型医疗设备的应用,出现了新的趋势,如:小型化、一体化、模块化和集成化。     

健康成人粪便中双歧杆菌的分离鉴定及其发酵乳体内特性研究

为筛选具有潜在益生功能的双歧杆菌,采用MRS培养基,结合菌落形态观察和16S rDNA基因序列同源性分析,从上海地区健康的成人粪便中分离鉴定双歧杆菌,通过7 L发酵罐发酵试验筛选优良菌株,并利用其制备发酵乳,对发酵乳的体内特性进行研究。结果表明,分离并鉴定到3株长双歧杆菌（Bifidobacterium longum）（编号为P-1、P-2和P-3）,其中菌株P-2制备的发酵乳在稳定期活菌数最高,遗传稳定性好,被确定为优良菌株,并被命名为DD98。菌株DD98制备的发酵乳能显著增加小鼠胃肠道内有益菌、减少有害菌的表达（P＜0.05）,具有调节肠道菌群的作用。此外,能维持小鼠正常的体质量、血常规指数,有利于小鼠脏器的生长。     

食用植物油中乙基麦芽酚测定干扰未知物分析

通过超高效液相色谱-三重四极杆质谱联用仪检测食用植物油样品,在乙基麦芽酚出峰保留时间附近出现易导致其结果误判的未知物,使用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱联用仪对未知物进行鉴定,结果表明该未知物是乙基麦芽酚酮式异构体。该试验首次确证了乙基麦芽酚的烯醇式和酮式异构体,为掺假食用植物油准确鉴定提供技术参考。     

硬脂酸改性β-磷酸三钙及其复合材料机械性能研究

为了提高β-磷酸三钙(β-TCP)复合材料的机械性能,采用硬脂酸(C17H25COOH)对β-TCP表面进行改性处理,研究了β-TCP与C17H25COOH的界面作用机理.利用透射电镜、傅里叶红外光谱、热重分析等技术分别对改性前后β-TCP的颗粒形貌、组分和表面—OH基团进行了表征,研究了改性β-TCP/聚左旋乳酸(PLLA)复合材料的机械性能,并利用扫描电镜观察了复合材料断面形貌.研究表明:硬脂酸包覆在β-TCP表面,改性后β-TCP粉末具有一定的疏水性,硬脂酸的H+可以与β-TCP中的PO43-的一个O发生质子化反应形成—OH.改性β-TCP/PLLA复合材料的机械性能相比改性前有明显提高,改性后的β-TCP微粒在PLLA中分散均匀,两者结合紧密.     

20Cr1Mo1VTiB钢的连续冷却转变行为

采用热膨胀仪测定20Cr1Mo1VTiB钢在不同淬火温度(950～1100℃)下的贝氏体转变点和较佳淬火温度下的连续冷却相变点,结合组织观察和硬度测试绘制连续冷却转变曲线;利用经验公式建立相变点和相转变量与冷却速率的关系,并计算相变激活能.结果表明:随着淬火温度升高,试验钢中贝氏体转变温度降低,较佳淬火温度为1050℃...     

计及合环约束的分布式电源与配电网联合优化

针对分布式电源(DG)出力不稳定以及线路负荷波动大对电网造成的不利影响,提出了一种计及合环约束的分布式电源与配电网联合优化模型。上层模型考虑线路拓扑重构,对DG进行选址定容;下层模型计及DG出力的时序特性,动态调整线路拓扑,进一步提升对于DG的接纳,并且优化线路的运行。同时,在重构的过程中考虑合环电流约束以确保方案的可行性,并采用二阶锥松弛将原问题转换为混合整数二阶锥规划。最后,在MATLAB环境下通过cplex求解器,以IEEE33节点模型为例开展仿真分析,验证了所提方法的有效性。     

Separable reversible data hiding in encrypted image based on pixel value ordering and additive homomorphism

This work proposes a separable reversible data hiding scheme in encrypted images based on pixel value ordering (PVO). After the original image is encrypted using homomorphism encryption by the content owner, the data hider embeds the secret data in encrypted domain. The PVO strategy realizes hiding data in each block. Additive homomorphism guarantees the performance of PVO in encrypted domain is close to that in plain domain. Besides, the homomorphism encryption does not cause data expansion, and the payload can be further improved. With the watermarked encrypted image, if the receiver has only the data hiding key, he can extract the additional data. If the receiver has only the encryption key, he can obtain a decrypted image similar to the original one. If the receiver has both the data hiding key and the encryption key, he can extract the additional data without any error and recover the original image losslessly.     

A new territory and its pioneer: opening up a dominant research stream for a translational research area

Scientometrics - An academic pioneer makes many trials to find relations and results that were unknown before. The verified relations and repeatable results the pioneer finds guide followers to...     

Research on the characteristics of atmospheric air dielectric barrier discharge under different square wave pulse polarities

Energy efficiency limits the application of atmospheric pressure dielectric barrier discharge(DBD),such as air purification,water treatment and material surface modification.This article focuses on the electrical and optical effects of the DBD under three square wave pulses polarities-positive,negative and bipolar.The result shows that under the same voltage with the quartz glass medium,the discharge efficiency of bipolar polarity pulse is the highest due to the influence of deposited charge.With the increase of air gap distance from 0.5 to 1.5 mm,average power consumed by the discharge air gap and discharge efficiency decrease obviously under alumina,and increase,and then decrease under quartz glass and polymethyl methacrylate(PMMA).Through spectrum diagnosis,in the quartz glass medium,the vibration temperature is the highest under negative polarity pulse excitation.Under bipolar pulse,the vibration temperature does not change significantly with the change of air gap distance.For the three dielectric materials of quartz glass,alumina and PMMA,the molecular vibration temperature is the highest under the quartz glass medium with the same voltage.When the gap spacing,pulse polarity or dielectric material are changed,the rotational temperature does not change significantly.