A self-powered and sensitive terahertz photodetection based on PdSe2

With the rapid development of terahertz technology, terahertz detectors are expected to play a key role in diverse areas such as homeland security and imaging, materials diagnostics, biology, medical sciences, and communication. Whereas self-powered, rapid response, and room temperature terahertz photodetectors are confronted with huge challenges. Here, we report a novel rapid response and self-powered terahertz photothermoelectronic (PTE) photodetector based on a low-dimensional material: palladium selenide (PdSe₂). An order of magnitude performance enhancement was observed in photodetection based on PdSe₂/graphene heterojunction that resulted from the integration of graphene and enhanced the Seebeck effect. Under 0.1-THz and 0.3-THz irradiations, the device displays a stable and repeatable photoresponse at room temperature without bias. Furthermore, rapid rise (5.0 μs) and decay (5.4 μs) times are recorded under 0.1-THz irradiation. Our results demonstrate the promising prospect of the detector based on PdSe₂ in terms of air-stable, suitable sensitivity and speed, which may have great application in terahertz detection.     

Facet-dependent antibacterial activity of Au nanocrystals

Engineered nanomaterials have attracted significantly attention as one of the most promising antimicrobial agents for against multidrug resistant infections. The toxicological responses of nanomaterials are closely related to their physicochemical properties, and establishment of a structure-activity relationship for nanomaterials at the nano-bio interface is of great significance for deep understanding antibacterial toxicity mechanisms of nanomaterials and designing safer antibacterial nanomaterials. In this study, the antibacterial behaviors of well-defined crystallographic facets of a series of Au nanocrystals, including {100}-facet cubes, {110}-facet rhombic dodecahedra, {111}-facet octahedra, {221}-facet trisoctahedra and {720}-facet concave cubes, was investigated, using the model bacteria Staphylococcus aureus. We find that Au nanocrystals display substantial facet-dependent antibacterial activities. The low-index facets of cubes, octahedra, and rhombic dodecahedra show considerable antibacterial activity, whereas the high-index facets of trisoctahedra and concave cubes remained inert under biological conditions. This result is in stark contrast to the previous paradigm that the high-index facets were considered to have higher bioactivity as compared with low-index facets. The antibacterial mechanism studies have shown that the facet-dependent antibacterial behaviors of Au nanocrystals are mainly caused by differential bacterial membrane damage as well as inhibition of cellular enzymatic activity and energy metabolism. The faceted Au nanocrystals are unique in that they do not induce generation of reactive oxygen species, as validated for most antibiotics and antimicrobial nanostructures. Our findings may provide a deeper understanding of facet-dependent toxicological responses and suggest the complexities of the nanomaterial-cell interactions, shedding some light on the development of high performance Au nanomaterials-based antibacterial therapeutics.     

Electronic and optical properties of Ho-doped BYF crystal

First-principles methods have been applied to explore the electronic and optical properties of BYF single crystals heavily doped with the Ho³⁺ ion (16.33 and 30.36 mol%). The electronic properties calculations manifest that the top of the valence band is dominated by 2p-orbitals of the F atoms and 4f-orbitals of the Ho atoms. The new defect states are dominated by 4f-orbitals of the Ho atoms which exist in the forbidden band. The principal absorptionat around 5.13 eV (241.7 nm) and 5.75 eV (215.7 nm) occurs in ultra-violet range owing to the electronic transitions from the occupied 2p-orbitalsof the F atoms as well as 4f-orbitals of the Ho atoms to empty 4f-orbitals of neighboring Ho atoms. Moreover, the influence of crystal field will split the energy levels of rare earth ions and easily release the parity forbidden condition of free rare earth ions resulting in f-f transition. Therefore, there may be a 2 μm luminescence in the Ho-doped BYF crystal.     

气相色谱–质谱法快速分析化妆品中3种香精香料

建立气相色谱-质谱法快速测定化妆品中甲基柏木酮、甲基柏木醚、壬酸3种香精香料的方法。样品用甲醇超声提取,经高速冷冻离心,上清液干燥脱水后经0.45 μm滤膜过滤,直接注入气相色谱-质谱仪进行测定,用选择离子和保留时间定性,外标法定量。甲基柏木酮、甲基柏木醚、壬酸在各自的质量浓度范围内与色谱峰面积成良好的线性关系,相关系数分别为0.9992,0.9991,0.9994,检出限分别为0.05,0.1,0.1 mg/kg。测定结果的相对标准偏差为2.1%~6.6%(n=5),样品加标回收率为91.5%~97.7%。该方法准确度和灵敏度高,样品用量少,前处理简单,可同时测定化妆品中3种香精香料。     

Degradable nanocatalyst enables antitumor/antibacterial therapy and promotion of wound healing for diabetes via self-enhanced cascading reaction

Diabetic patients often have problems such as residual tumor and wound infection after tumor resection, causing severe clinical problems. It is urgent to develop effective therapies to reach oncotherapy/anti-infection/promotion of wound healing combined treatment. Herein, we propose CS/MnO₂-GOx (CMGOx) nanocatalysts for the specific catalytic generation of ^•OH to inhibit tumors and bacteria in a hyperglycemic environment. The good biocompatible chitosan (CS), as a carrier for the catalyst, exhibits excellent antibacterial effect as well as promotes wound healing. Glucose oxidase (GOx) is loaded on the surface of CS nanoparticles to generate H₂O₂ and gluconic acid by consuming glucose (starvation therapy, ST) and O₂. The MnO₂ depletes glutathione (GSH) to produce Mn²⁺, amplifying oxidative stress and further promoting the activity of Mn²⁺-mediated Fenton-like reaction to produce ^•OH (chemodynamic therapy, CDT) in weak acidic environment. Moreover, the produced gluconic acid lowers the pH of the environment, enhancing chemodynamic therapy (ECDT). The tumor cells and bacteria are efficiently eliminated by the synergistic effect of ST and ECDT. The MnO₂ nanoparticles at neutral environment decomposes H₂O₂ into O₂, which cooperate with CS to promote healing. The self-enhanced cascade reaction of CMGOx in situ exhibits excellent effects of antitumor/antibacterial therapy and promotion of wound healing, offering a promising integrated treatment for diabetic patients after tumor surgical resection.     

Zwitterionic comb-like lipid polymers encapsulating linalool for increasing the fragrance retention time

Fragrances are widely used in cosmetics,apparel and detergents.However,the rapid evaporation of the aro ma shortens the useful life of the aromatic product.Therefore,improving the fragrance retention time of aromatic products and prolonging the service life of aromatic products are the key scientific problems that need to be solved in current aromatic products.In this study,zwitterionic comb-like lipid polymers were synthesized to encapsulate the fragrance molecule linalool.The results showed that the zwitterionic comb lipid molecules were capable of encapsulating more linalool than linear lipid molecules.At the same time,the zwitterionic comb-like lipid molecules also limited the slow release rate of the aroma,thereby increasing the fragrance retention time of the nano-fragrance.     

集成光芯片的电光性能测试方法

为了提高中低精度光纤陀螺工程化批产过程中的一致性和合格率,降低筛选成本,初步定量研究了铌酸锂集成光芯片的附加损耗、光克尔效应、分光比和偏振效应等重要参数对陀螺性能的影响和优化方法,并提出了电光性能的具体测试方法。通过输入特定方波、锯齿波、方波加阶梯波,可从输出波形上进行直观的判断,并可进一步给出性能优劣的量化指标,能够较为准确地进行芯片筛选,提高工艺水平。此项研究成果对铌酸锂集成光芯片的相关标准进行了补充,不仅可以帮助光纤陀螺的制作单位进行更合理可行的器件筛选,还可以帮助芯片的生产单位完善相应的参数测试工作,提高合格率。     

特征根估计方法在SINS制导工具误差估计中的应用

特征根估计方法具有降低模型复共线性程度和提高参数估计效果的作用,但是在SINS制导工具误差估计中,如何有效地筛选特征根却成为特征根估计的重要问题。文中通过研究特征根与残差平方和之间的关系,提出了以残差平方和与系统阶次比最小为准则(即MRSO准则)的特征根筛选方法。仿真分析表明,改进的特征根估计方法具有很强的工程实践性,从而推动了该方法在实际工程中广泛应用。