纳米结构薄膜型气敏传感器的研究进展

薄膜型气敏器件对气体具有探测灵敏度高、响应时间快、制备成本较低、易于小型化等特点,并且适于制备微型传感器,因此成为近年来传感器研究的重点。将纳米结构材料制作成薄膜型气敏传感器,具有常规传感器不可替代的优点:纳米结构构成的固体材料具有庞大的界面,提供了大量气体通道,从而大幅度提高了灵敏度和降低了工作温度,并可缩小传感器的尺寸。文章主要介绍了当前国内外纳米结构薄膜型气敏传感器的研究现状,概述了几种常见的纳米结构单元薄膜的气敏特性,扼要地分析了今后纳米薄膜型传感器的研究趋势。     

纳米结构薄膜型气敏传感器的研究进展

薄膜型气敏器件对气体具有探测灵敏度高、响应时间快、制备成本较低、易于小型化等特点,并且适于制备微型传感器,因此成为近年来传感器研究的重点。将纳米结构材料制作成薄膜型气敏传感器,具有常规传感器不可替代的优点：纳米结构构成的固体材料具有庞大的界面,提供了大量气体通道,从而大幅度提高了灵敏度和降低了工作温度,并可缩小传感器的尺寸。文章主要介绍了当前国内外纳米结构薄膜型气敏传感器的研究现状,概述了几种常见的纳米结构单元薄膜的气敏特性,扼要地分析了今后纳米薄膜型传感器的研究趋势。     

细胞膜伪装的纳米载体用于光热治疗的研究进展

纳米载体一直是肿瘤精准治疗的重要研究领域。其中以细胞膜伪装的纳米药物载体作为一种新颖的药物载体平台,在近年来已成为药物传递领域的研究热点。本文综述了不同种类细胞膜伪装的纳米载体应用于光热治疗的最新进展。将细胞膜与纳米材料结合起来,可进一步推进纳米载体的研究,这将对相关领域的发展产生重要影响。     

金纳米粒子的放射增敏效应研究

系统阐述了与金纳米粒子(GNPs) 放射增敏效应相关实验的方法与结果、影响GNPs 放射增敏的因素、GNPs 放射增敏的细胞和动物实验表现及其相关机制。同时结合相关实验,分析和比较了15 nm 柠檬酸钠包被的GNPs 的放射增敏效应,发现GNPs 在高LET 的碳离子束和低LET 的X射线辐照下对Hela细胞的杀伤力随其浓度的增加而增大;在50% 的细胞存活率下,当GNPs 的质量浓度为7.5 g/mL时,其X射线的剂量减少率和碳离子的相对生物学效应值(RBE) 的增加率达到了最大,分别为65.3% 和43.6%,同时GNPs 共培养细胞24 和48 h 后,未出现细胞周期同步化的现象。This paper describes the methods and results of the previous experiments, the experimental phenomena of the cell and animal tests and the relative mechanisms on the radiosensitizing effect of GNPs. Together with our experiments, the radiosensitizing effects of 15 nm citrate-capped GNPs and related mechanisms are analyzed and compared, finding that Hela cell killing of GNPs increase along with their concentration after exposure to high- and low-LET radiation such as carbon ions and X-rays. In addition, the percentages of dose reduction of the X-rays and RBE increment of the carbon ions reached their maximums 65.3% and 43.6%, respectively,at 50% survival level when Hela cells were pre-treated with 7.5 g/mL GNPs. Moreover, Hela cells showed no cell-cycle synchronization after 24 and 48 h exposure to GNPs.     

长余辉纳米诊疗剂的设计策略与应用研究进展

长余辉纳米材料具有激发/发射分离、成像分辨率高、大面积成像与操作模式便捷等优点,在高灵敏度生物医学光学诊断领域引起了广泛关注。然而,随着诊疗一体化需求的增加,现有长余辉纳米材料功能的单一性阻碍了其在微型化、集成化诊疗上的快速发展。基于此,本综述针对生物医学诊疗集成一体化的长余辉纳米诊疗剂开发,展示了相应的设计策略和合成方法,并指出了长余辉纳米诊疗剂的研究前景、机遇及未来的发展方向。     

基于相干光时域反射型的光纤分布式声增敏传感研究

开展了基于相干光时域反射型的光纤分布式声增敏传感研究,提出了单端固定开口波纹薄筒光纤声增敏方法,建立了光纤声增敏装置波节间距、单波节轴向刚度、光纤长度等参数对光纤相位灵敏度的影响理论模型.制作了3种规格的光纤声增敏传感装置进行声传感实验.实验结果表明,声增敏传感装置相位灵敏度达到2.975 rad/Pa,最小声探测信号达到60.1 dB,3种规格的声增敏传感装置的灵敏度测试值与理论分析基本一致.研究结果为高灵敏度的光纤分布式声传感的进一步发展提供了理论和实验基础.     

退火温度对纳米氧化铜湿敏性能的影响

湿度传感器在生产和生活中扮演着不容小觑的角色,越来越受到人们的广泛关注.本文利用低温液相法以氢氧化钠、过硫酸铵和铜粉为原料,成功制备出氧化铜纳米结构.运用扫描电子显微镜(SEM)、X-射线衍射仪(XRD)等技术对材料的结构与形貌进行表征,发现可以通过退火温度来调控氧化铜纳米结构的表面形貌,进一步比较研究了不同退火温度下制备的纳米氧化铜的湿敏性能.并将CuO纳米材料涂敷在电极表面制成了湿敏元件.研究结果表明,元件的湿敏特性明显与材料的退火温度密切相关,在500℃退火获得的氧化铜纳米线灵敏度最高,达到1.93×10~5;湿滞最小,几乎为零;感湿频率特性曲线的线性度好.分析认为这主要是由于,退火温度500℃时,氧化铜呈现纳米线状结构,具有更大的表面积,增加了与水分子的接触面积,进而具有更佳的湿敏特性.     

纳米SrTiO3的光声光谱研究

利用光声光谱技术对不同退火温度的纳米SrTiO₃粉末进行了研究．结果表明，纳米SrTiO₃粉末随退火温度升高，吸收边红移，说明能隙变窄，这与颗粒长大、晶格参数减小有关．在700nm附近出现的宽吸收带是由氧缺位俘获的电子在缺陷附加能级上的跃迁所产生的，其变化趋势强烈地依赖于颗粒尺寸 关键词：     

功能性硫化镉纳米粒子荧光增敏法测定诺氟沙星

室温条件下在水溶液中以硫代乙酰胺和硝酸镉为原料,采用微波法合成了粒度分布均匀、分散性好的CdS纳米粒子,在pH 7.4时,CdS纳米粒子的荧光强度能够被诺氟沙星增敏,且CdS纳米粒子的荧光光谱显示其带边发射位于495 nm,缺陷发射位于565 nm而且不明显,所以表明合成的CdS纳米粒子的光学性质较好,同时紫外吸收光谱和透射电子显微镜也证明了此推论。同时考察了缓冲液、pH值、离子强度、反应时间和温度等条件因素对CdS纳米粒子-诺氟沙星复合体系荧光光谱特性的影响。探讨了在最佳实验条件下,CdS纳米粒子与诺氟沙星之间的可能作用机理,荧光光谱法显示CdS纳米粒子的增加强度与诺氟沙星浓度成正比, 其浓度范围为1.25～11.25 μg·mL-1或11.25～100.0 μg·mL-1,检测限为1.5×10-3 μg·mL-1。该方法为研究诺氟沙星含量测定提供了一种新的思路, 同时为研究其在体内代谢提供了一定的指导意义。     

基于NASIC程序的纳米金辐射增敏效应模拟研究

纳米金粒子（GNP）应用为放疗辐射增敏剂是目前国际上的一个研究热点。使用自主研发的纳剂量生物物理蒙特卡罗程序(NASIC),模拟研究了光子照射下细胞环境中GNP的物理增敏效应和生物增敏效应。通过建立单个GNP位于细胞核中心以及多个GNP在细胞内四种理想分布的GNP-细胞模型,分析光子能量、GNP粒子尺寸和分布对能量沉积、DNA辐射损伤和细胞存活的影响。结果表明,GNP附近约2 m的范围内具有能量沉积的增强效应,这主要是因为GNP内光电效应作用数目的显著增加。不同条件下细胞核内能量沉积、DSB数目和细胞存活分数增强效应的变化规律基本一致,但增强因子呈递减趋势,三种评价指标增强因子的最大值分别为1.55,1.32 和1.14。光子能量为40 keV、GNP直径为100 nm并分布在细胞核表面时,相比其他参数组合具有较高的物理和生物辐射增敏效应。     

Recent advances in sonodynamic approach to cancer therapy

Chemical agents such as porphyrins were found to be activated by ultrasound, producing significant antitumor effects. Hematoporphyrin (Hp) enhanced ultrasonically induced damage on sarcoma cells and shown a synergistic inhibitory effect on the tumor growth in combination with ultrasound at 2 MHz. Recently, other types of porphyrins such as protoporphyrin were also found to have such sonodynamic activities. Furthermore, it was found that sonochemical reactions can be greatly accelerated by superimposing the second harmonic onto the fundamental. The highest rate of iodine release from aqueous iodide was obtained at an acoustic intensity ratio between 1 MHz and 2 MHz of 1:1 while either one of the frequency components alone could not induce significant iodine release at the same total acoustic intensity. Second-harmonic superimposition in combination with sonodynamically active antitumor agents may have the potential for selective tumor treatment.     

Recent progress and new challenges in isospin physics with heavy-ion reactions

The ultimate goal of studying isospin physics via heavy-ion reactions with neutron-rich, stable and/or radioactive nuclei is to explore the isospin dependence of in-medium nuclear effective interactions and the equation of state of neutron-rich nuclear matter, particularly the isospin-dependent term in the equation of state, i.e., the density dependence of the symmetry energy. Because of its great importance for understanding many phenomena in both nuclear physics and astrophysics, the study of the density dependence of the nuclear symmetry energy has been the main focus of the intermediate-energy heavy-ion physics community during the last decade, and significant progress has been achieved both experimentally and theoretically. In particular, a number of phenomena or observables have been identified as sensitive probes to the density dependence of nuclear symmetry energy. Experimental studies have confirmed some of these interesting isospin-dependent effects and allowed us to constrain relatively stringently the symmetry energy at sub-saturation densities. The impact of this constrained density dependence of the symmetry energy on the properties of neutron stars have also been studied, and they were found to be very useful for the astrophysical community. With new opportunities provided by the various radioactive beam facilities being constructed around the world, the study of isospin physics is expected to remain one of the forefront research areas in nuclear physics. In this report, we review the major progress achieved during the last decade in isospin physics with heavy ion reactions and discuss future challenges to the most important issues in this field.     

Modeling soot formation in flames and reactors: Recent progress and current challenges

The study of soot has long been motivated by its adverse impacts on health and the environment. However, this combustion knowledge is also relevant to the production of carbon black and hydrogen via methane pyrolysis which are important commodities. Over the last decade, steady progress has been made in the development of detailed continuum models of soot formation in flames and reactors. Developing more comprehensive models has often been motivated by the need for predicting soot formation over a wider range of conditions (e.g., temperature, pressure, fuels). Measurements with novel experimental techniques have given us new insights into the chemistry, particle dynamics and optical properties of soot particles and even molecules and radicals forming them. Also, multi-scale modeling has enabled us to translate the detailed mechanisms of soot processes based on first principles into computationally efficient but accurate continuum models of soot formation in flames and reactors. However, important questions remain including (1) what is the mechanism of soot inception and surface growth, (2) which gas-phase species are involved in soot inception and surface growth (3) how surface growth and oxidation are affected by soot surface properties. Proposed models need to be evaluated against experimental data over a wide range of conditions to determine their predictive strength. These questions are critical for the accurate prediction of soot formation in flames and its emissions from engines. However, this knowledge can also be used to develop predictive process design and optimization tools for carbon black and other nanocarbon formation in reactors.     

Recent progress in multi-wavelength fiber lasers:principles,status,and challenges

In recent years,multi-wavelength fiber lasers play a significant role in plenty of fields,ranging from optical communications to mechanical processing and laser biomedicine,owing to their high beam quality,low cost,and excellent heat dissipation properties.Benefitting from increasing maturity of optical elements,the multi-wavelength fiber laser has made rapid developments.In this review,we summarize and analyze diverse implementation methods covering continuous wave and pulsed fiber lasers at room temperature conditions:inserting an optical filter device and intensity-dependent loss structure in the resonant cavity,and applying ultrafast nonlinear optical response of materials and a dual-cavity structure.Finally,future challenges and perspectives of the multi-wavelength fiber laser are discussed and addressed.     

Current status and future perspectives of sonodynamic therapy in glioma treatment

Malignant glioma is one of the most challenging central nervous system diseases to treat, and has high rates of recurrence and mortality. The current therapies include surgery, radiation therapy, and chemotherapy, although these approaches often failed to control tumor progression or improve patient survival. Sonodynamic therapy is a developing cancer treatment that uses ultrasound combined with a sonosensitizer to synergistically kill tumor cells, and has provided impressive results in both in vitro and in vivo studies. The ultrasound waves can penetrate deep tissues and reversibly open the blood-brain barrier to enhance drug delivery to the brain. Thus, sonodynamic therapy has a promising potential in glioma treatment. In this review, we summarize the studies that have confirmed the pre-clinical efficacy of sonodynamic therapy for glioma treatment, and discuss the future directions for this emerging treatment.     

Targeted sonodynamic therapy using protein-modified TiO2 nanoparticles

Our previous study suggested new sonodynamic therapy for cancer cells based on the delivery of titanium dioxide (TiO₂) nanoparticles (NPs) modified with a protein specifically recognizing target cells and subsequent generation of hydroxyl radicals from TiO₂ NPs activated by external ultrasound irradiation (called TiO₂/US treatment). The present study first examined the uptake behavior of TiO₂ NPs modified with pre-S1/S2 (model protein-recognizing hepatocytes) by HepG2 cells for 24 h. It took 6 h for sufficient uptake of the TiO₂ NPs by the cells. Next, the effect of the TiO₂/US treatment on HepG2 cell growth was examined for 96 h after the 1 MHz ultrasound was irradiated (0.1 W/cm², 30 s) to the cells which incorporated the TiO₂ NPs. Apoptosis was observed at 6 h after the TiO₂/US treatment. Although no apparent cell-injury was observed until 24 h after the treatment, the viable cell concentration had deteriorated to 46% of the control at 96 h. Finally, the TiO₂/US treatment was applied to a mouse xenograft model. The pre-S1/S2-immobilized TiO₂ (0.1 mg) was directly injected into tumors, followed by 1 MHz ultrasound irradiation at 1.0 W/cm² for 60 s. As a result of the treatment repeated five times within 13 days, tumor growth could be hampered up to 28 days compared with the control conditions.     

Recent advances and open challenges in percolation

Percolation is the paradigm for random connectivity and has been one of the most applied statistical models. With simple geometrical rules a transition is obtained which is related to magnetic models. This transition is, in all dimensions, one of the most robust continuous transitions known. We present a very brief overview of more than 60 years of work in this area and discuss several open questions for a variety of models, including classical, explosive, invasion, bootstrap, and correlated percolation.     

Enhanced sonodynamic therapy by carbon dots-shelled microbubbles with focused ultrasound

Sonodynamic therapy involving the non-invasive and local generation of lethal reactive oxygen species (ROS) via ultrasound (US) with sonosensitizers has been proposed as an emerging tumor therapy strategy. However, such therapy is usually associated with inertial cavitation and unnecessary damage to healthy tissue because current sonosensitizers have insufficient sensitivity to US. Here, we report the use of a new proposed sonosensitizer, carbon dots (C-dots), to assemble microbubbles with a gas core (C-dots MBs). As the C-dots were directly integrated into the MB shell, they could effectively absorb the energy of inertial cavitation and transfer it to ROS. Our results revealed the appearance of ¹O₂, •OH, and H₂O₂ after US irradiation of C-dots MBs. In in vitro experiments, treatment with C-dots MBs plus US induced lipid peroxidation, elevation of intracellular ROS, and apoptosis in 32.5%, 45.3%, and 50.1% of cells respectively. In an animal solid tumor model, treatment with C-dots MBs plus US resulted in a 3-fold and 2.5-fold increase in the proportion of ROS-damaged cells and apoptotic cells, respectively, compared to C-dots MBs alone. These results will pave the way for the design of novel multifunctional sonosensitizers for SDT tumor therapy.     

自旋电子学研究与进展

自旋电子学是最近几年在凝聚态物理中发展起来的新学科分支,它研究在固体中自旋自由度的有效控制和操纵,在金属和半导体中自旋极化、自旋动力学、自旋极化的输运和自旋电子检测.由于它在信息存储方面的重大应用前景,受到学术界和工业界的高度重视.文章扼要地介绍了自旋电子学发展的历程和发展中的最重要的发现.最近几年,最奇特的发现和最重要的应用莫过于巨磁电阻,薄膜领域纳米技术的迅速发展使巨磁电阻的应用变成可能.作为磁记录头它已使硬磁盘的记录密度提高到170Gbit/in2.动态随机存储器MRAM的研究已实现16Mbit的存储密度.     

X射线光刻技术的进展及问题

Ｘ射线光刻是一种能满足下世纪初超大规模集成电路（ＶＬＳＩ）生产的深亚微米图形加工技术。论述了这种光刻技术的发展历史及近年来的主要进展。重点讨论了在Ｘ射线源、接近式曝光和全反射投影曝光等方面取得的成就与存在的问题。展望了这种技术的发展前景