基于光纤锥级联结构的湿度传感器

提出了一种基于普通单模光纤粗锥级联结构的马赫-曾德尔干涉湿度传感器.将两根单模光纤对芯熔融成一个粗锥,并依次级联,形成光纤锥-单模光纤-光纤锥-单模光纤-光纤锥结构.外界环境湿度、温度的改变使传感器的纤芯基模和包层模的光程差发生改变,引起传感器干涉光谱发生变化.通过监测干涉谱波长和能量的变化实现对外界物理量的测量.实验结果表明,当空气中湿度在35~95%RH范围内变化时,传感器的湿度灵敏度为-0.065dB/%RH,线性度为0.997;当温度在30~80℃范围内变化时传感器的温度灵敏度为69.4pm/℃,线性度为0.998.该传感器可以避免温湿度的交叉影响,实现单参量的同时在线区分测量.     

Application of sol–gel TiO2 film for an extended-gate H+ ion-sensitive field-effect transistor

In this study, a sol–gel TiO₂ thin film has been spin-coated on a commercial ITO glass substrate as the extended-gate field effect transistor (EGFET) for hydrogen ion sensing. The as-deposited films are further annealed at various temperatures (T_a) under ambient atmosphere. It is found that the bi-layer structure of TiO₂/ITO EGFET exhibits good linear sensitivity from pH 1 to 11. Anatase TiO₂ appeared as early as T_a = 200 °C and a brookite (121) diffraction evolved at T_a = 500 °C. No prominent influence on the surface fine structures could be found at higher T_a. Due to the reduction or disappearance of the surface hydroxyl groups on TiO₂, the sensitivities of the TiO₂/ITO pH-EGFET device are rapidly reduced. However, the influence of the conductivity decay for ITO substrates annealed at high T_a could not be excluded. A maximum sensitivity 61.44 mV/pH is achieved as T_a = 300 °C.The bi-layer structure of TiO₂/ITO exhibits better long-term stability than the traditional ITO sensing membranes. In addition, the asymmetric hysteresis is more significant in alkaline buffer solutions, which could be explained by a site-binding model because the diffusion of H⁺ ions into the buried sites of the sensing film is more rapid than that of OH⁻ ions.     

Efficacious Anticancer Drug Delivery Mediated by a pH‐Sensitive Self‐Assembly of a Conserved Tripeptide Derived from Tyrosine Kinase NGF Receptor

We present herein a short tripeptide sequence (Lys–Phe–Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self‐assembles in water and shows a reversible and concentration‐dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH‐sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug‐sensitive and drug‐resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence‐activated cell sorting analysis, fluorescence microscopy, and confocal microscopy.     

疏水改性pH响应型智能水凝胶P(HEMA-NaAA-DiAC16)的制备及其溶胀性能

以二烯丙基胺和1-溴代十六烷为原料合成了疏水单体N,N-二烯丙基正十六烷胺(DiAC16),用FTIR、1H NMR 和元素分析对其进行了表征。 以2-羟基甲基丙烯酸乙酯(HEMA)、丙烯酸(AA)和N,N-二烯丙基正十六烷胺为共聚单体,N,N′-亚甲基双丙烯酰胺(BIS)为交联剂,十二烷基硫酸钠(SDS)为表面活性剂,过硫酸铵-四甲基乙二胺(TMEDA)为引发体系,制得的疏水改性智能水凝胶P(HEMA-NaAA-DiAC16)具有pH敏感特性。 研究了DiAC16、NaAA、BIS用量及pH值和离子强度等因素对水凝胶P(HEMA-NaAA-DiAC16)溶胀性能的影响。 结果表明,凝胶在水中的平衡溶胀率(为78.9～163.91),随DiAC16、BIS用量的增加和NaAA用量的减少而减少,n值(一般在0.5~1.0之间)随DiAC16、NaAA和BIS用量的增加而增加,为非Fickian扩散。 水凝胶的吸水溶胀是放热过程,ΔHm在-2.09～-3.64 kJ/mol,ΔHm的绝对值随DiAC16用量的减少、NaAA用量和BIS用量的增加而增大,聚合物与水的亲和力逐渐增强。 随离子强度的增强,平衡溶胀率下降。     

Strain rate sensitivity of polyurea coatings: Viscous and elastic contributions

Polyurea, a reaction product of isocyanates and an amine blend has been reported to be highly strain rate sensitive, which responds in its own unique way when subjected to increasing strain rates. The amine blend comprise of a long chain amine, forming the soft segments, chain extender, which brings the urea linkages closer and a crosslinker, which serves as a chemical bond between the chains. In this work, we attempt to tune the viscous contribution in polyurea, by increasing crosslinking density, while keeping the amount of chain extender more or less constant. The viscoelastic behavior and its effect on the time dependant behavior was established by extensive dynamic studies. Quasi-static tests and Split Hopkinson testing was performed over large deformation rates (10⁻⁴ to 10³ s⁻¹). It was observed that polyureas with larger viscous contribution (tan δ), were capable of exhibiting larger strain rate sensitivity.     

Amphibious sensor of temperature and refractive index based on D-shaped photonic crystal fibre filled with liquid crystal

ABSTRACT

A D-shaped photonic crystal fibre filled with liquid crystal was demonstrated as an amphibious sensor for detection of both temperature and refractive index, when combined with plasma materials. Specifically, the optical component is implanted into a complete optical system ensuring modulation of the external electric field. When the refractive index of the external solution changes from 1.0 to 1.6, the y-polarised mode has a loss spectrum with a wavelength sensitivity of up to 2275 nm/RIU, and the corresponding amplitude sensitivity is ?88.2RIU^?1. When the perceived temperature changes from 15°C to 50°C, the temperature of the sensor is correspondingly expressed as the maximum wavelength sensitivity of 9.09 nm/°C and the amplitude sensitivity of ?0.311°C^?1. In addition, the actual micro-operation processes have been studied in detail, such as polishing depth, coating thickness and coating method. This provides practical ideas for real-time sensing analysis that requires harsh environments.     

Nitro-, Cyano-, and Methylfuroxans,and Their Bis-Derivatives: From Green Primary to Melt-Cast Explosives

In the present work, we studied in detail the thermochemistry, thermal stability, mechanical sensitivity, and detonation performance for 20 nitro-, cyano-, and methyl derivatives of 1,2,5-oxadiazole-2-oxide (furoxan), along with their bis-derivatives. For all species studied, we also determined the reliable values of the gas-phase formation enthalpies using highly accurate multilevel procedures W2-F12 and/or W1-F12 in conjunction with the atomization energy approach and isodesmic reactions with the domain-based local pair natural orbital (DLPNO) modifications of the coupled-cluster techniques. Apart from this, we proposed reliable benchmark values of the formation enthalpies of furoxan and a number of its (azo)bis-derivatives. Additionally, we reported the previously unknown crystal structure of 3-cyano-4-nitrofuroxan. Among the monocyclic compounds, 3-nitro-4-cyclopropyl and dicyano derivatives of furoxan outperformed trinitrotoluene, a benchmark melt-cast explosive, exhibited decent thermal stability (decomposition temperature >200 °C) and insensitivity to mechanical stimuli while having notable volatility and low melting points. In turn, 4,4′-azobis-dicarbamoyl furoxan is proposed as a substitute of pentaerythritol tetranitrate, a benchmark brisant high explosive. Finally, the application prospects of 3,3′-azobis-dinitro furoxan, one of the most powerful energetic materials synthesized up to date, are limited due to the tremendously high mechanical sensitivity of this compound. Overall, the investigated derivatives of furoxan comprise multipurpose green energetic materials, including primary, secondary, melt-cast, low-sensitive explosives, and an energetic liquid.     

Modeling and testing of snow penetration

Penetration by a cone into snow is commonly used to characterize snow properties. However, the effects of the diameter and half-angle of the cone on the mechanical properties of snow have not been systematically studied. In addition, no estimation of material parameters in a physically-based model has been made such that the results from penetration provide only an index of snow properties. In this paper, modeling and experimental methods are used to examine the effects of cone geometry on the maximum penetration force and associated hardness, with penetrometers ranging from 2.5 to 4 mm in diameter, 15° to 45° in cone half-angle, and testing both fine-grained and coarse-grained snows. The material point method, in conjunction with the Drucker–Prager cap plasticity model, was used to obtain the theoretical penetration force-distance relationship. Global sensitivity studies were conducted that indicate that the cohesion accounts for 86% of the penetration force, followed distantly by friction angle which accounts for 27%. A general trend, for the simulation results was established: for a given half-angle, the penetration force increases with the increase of diameter which holds for most of the test data as well; for a given diameter, the penetration force decreases with the increase of half-angle, which holds for some of the test data. In addition, for a given half-angle, the hardness decreases with the increase of diameter; for a given diameter, the hardness decreases with the increase of half-angle. To take into consideration the uncertainty of test data, a simple interval-based metric was used to compare test data with simulation results; the comparison was satisfactory. The material parameters from the simulations can thus be considered as calibrated ones for the snow studied.     

AN EFFICIENT SEQUENTIAL DESIGN FOR SENSITIVITY EXPERIMENTS

In sensitivity experiments, the response is binary and each experimental unit has a critical stimulus level that cannot be observed directly. It is often of interest to estimate extreme quantiles of the distribution of these critical stimulus levels over the tested products. For this purpose a new sequential scheme is proposed with some commonly used models. By using the bootstrap repeated-sampling principle, reasonable prior distributions based on a historic data set are specified. Then, a Bayesian strategy for the sequential procedure is provided and the estimator is given. Further, a high order approximation for such an estimator is explored and its consistency is proven. A simulation study shows that the proposed method gives superior performances over the existing methods.     

Anion influenced self-assembly of stilbazolium derivative and acid-sensitive property of its corresponding gel

Two stilbazolium derivatives with different counter-anions (Br^?  and OH^? ) have been designed and synthesised. Different counter-anions cause different aggregation properties. The reason of this difference was investigated through concentration- and temperature-dependent ¹H NMR and IR spectra. When the counter-anion is OH^? , the stilbazolium derivative exhibits pronounced aggregation properties. The scanning electron microscope images of xerogels show the characteristic gelation morphologies of 3D fibrous network structures. X-ray diffraction and fluorescence spectroscopy studies have been carried out, and provide more information to define the molecular packing model in gelation states. Finally, the acid-sensing abilities of the xerogel film were studied.