Modulating Charge Carrier Efficient Separation Enabled by Lewis Base Modification in Paper-based Photoelectrochemical Sensor

The separation efficiency of charge carriers determines the analytical sensitivity of the paper-based photoelectrochemical sensor. Herein, the Lewis base modification strategy is proposed to promote the carrier separation through an in-situ ion exchange method. Firstly, three-dimensional paper-based hierarchically TiO₂ (PHT) arrays are prepared with the one-step hydrothermal method. With the aid of Lewis base, the photo-induced charge separation efficiency and the photocurrent signal are obviously increased. Ultimately, sensitive sensing of prostate specific antigen (PSA) is achieved and the linear range is 1 pg/mL–100 ng/mL with the detection limitation of 0.3 pg/mL.     

纳米线组装叶片状三氧化钼的合成及其对三乙胺的气敏性能

通过溶剂热法制备了由一维纳米线自组装的叶状三氧化钼纳米材料，借助X射线衍射（XRD）、场发射扫描电子显微镜（FESEM）、透射电子显微镜（TEM）、高分辨透射电镜（HRTEM）、紫外-可见漫反射光谱（UV-Vis DRS）、热重-示差扫描量热（TG-DSC）、氮气吸附（N₂-sorption）等技术对材料进行了系统的组成和结构表征。结果表明，一维纳米线表面具有粗糙结构，且由一维纳米线组装的叶片状三氧化钼属畸变八面体中的正交晶系，其主要暴露的结晶面是（021）。此叶片状三氧化钼气敏材料在300℃的最佳工作温度下，对2.25 g·m^-3的三乙胺表现出优异的选择性、超高的灵敏度和较快的响应时间（5 s），甚至在浓度为4.5 mg·m^-3的检测标准下响应值仍可达到12.4。基于以上结构表征和性能测试结果，对叶片状三氧化钼的形成及三乙胺敏感机理进行了初步探讨分析。     

强度解调型光纤光栅温度传感实验

光纤光栅在工程上应用广泛,但由于存在解调系统复杂、成本高,尤其是需要使用光纤光谱仪等波长解调仪器,使得光纤光栅很难走入本科教学的实验课堂.本文提出了一种基于窄线宽DFB激光器的强度解调方案,极大地简化了光纤光栅传感器的解调系统,完全满足较高分辨率和实时检测的系统要求.合理安排的温度传感实验可以非常直观地展示光纤光栅的线性传感性能,使得工程化的光纤光栅传感技术轻松走进本科教学课堂,具有极高的推广和应用潜力.     

New oxacalix[4]arene carboxylate detects viologen in protic media

ABSTRACT

We demonstrate that Ullman fragment-coupling can be used to synthesise an oxacalix[4]arene monocarboxylic acid, which provides easy access to its water-soluble carboxylato derivatives. Crystallographic and computational data suggest that the new carboxyl-substituted oxacalix[4]arene adopts a 1,3-alternate conformation both in the solid-state and in methanol solution. Its water-soluble tetrabutylammonium derivate can detect the herbicide paraquat at neutral pH in aqueous media (K _a = 111 ± 3 M^–1) and in methanol (K _a = 2020 ± 70 M^–1).     

Free radical oxidation reaction for selectively solvatochromic sensors with dynamic sensing ability

A novel BODIPY (boradiazaindacene) dye denoted as BODIPY-DT containing terpyridine unit has been designed and characterized. The dye is found to be selective and visual solvatochromic sensor toward DMF among test organic solvents. The sensing process displays time-controllable, dynamic signal outputs in the emission colors including red, purple, yellow and even white emission colors. It is presented that selective free radical oxidation reaction happens during the recognition process.     

B-, N-doped and BN codoped C60 heterofullerenes for environmental monitoring of NO and NO2: a DFT study

ABSTRACT

Using density functional theory calculations, we investigate the gas sensing performance of B-, N-doped and BN-codoped C₆₀ fullerenes towards NO and NO₂ molecules. The calculated adsorption energies and net charge-transfer values indicate that NO and NO₂ molecules have a stronger interaction with the BN-codoped fullerenes compared to the B- or N-doped ones. It is also found that the electronic properties of the BN-codoped C₆₀ exhibit a larger sensitivity towards NO and NO₂ molecules. An increase in the concentration of doped/co-doped B and N atoms tends to weaken the gas sensing ability of these systems.     

Tandem Use of Optical Sensing and Machine Learning for the Determination of Absolute Configuration,Enantiomeric and Diastereomeric Ratios,and Concentration of Chiral Samples

We have developed an optical method for accurate concentration, er, and dr analysis of amino alcohols based on a simple mix‐and‐measure workflow that is fully adaptable to multiwell plate technology and microscale analysis. The conversion of the four aminoindanol stereoisomers with salicylaldehyde to the corresponding Schiff base allows analysis of the dr based on a change in the UV maximum at 420 nm that is very different for the homo‐ and heterochiral diastereomers and of the concentration of the sample using a hypsochromic shift of another absorption band around 340 nm that is independent of the analyte stereochemistry. Subsequent in situ formation of Cu^II assemblies in the absence and presence of base enables quantification of the er values for each diastereomeric pair by CD analysis. Applying a linear programming method and a parameter sweep algorithm, we determined the concentration and relative amounts of each of the four stereoisomers in 20 samples of vastly different stereoisomeric compositions with an averaged absolute percent error of 1.7 %.     

A self-penetrating and chemically stable zinc (ii)-organic framework as multi-responsive chemo-sensor to detect pesticide and antibiotics in water

Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)_0.5(bimb)]·H₂O}_n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {8⁶} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium.     

光子晶体光纤温度压力传感器

提出了一种在高温环境下同时测量温度和气压的光子晶体光纤温度压力传感器.在普通单模光纤和光子晶体光纤之间熔接一段空心光纤构成干涉结构.空心光纤段构成非本征法布里-珀罗干涉仪,利用光子晶体光纤的微孔与外界相通,通过气体折射率变化来测量环境中的气压变化;光子晶体光纤段构成本征法布里-珀罗干涉仪,利用热膨胀效应和热光效应来测量环境中的温度.传感器的解调通过自制的白光干涉解调仪实现,实验通过测量腔长得到被测环境的温度和气压.在不同温度和气压环境下,对腔长分别为306μm和1535μm的温度压力光纤传感器进行连续测量.实验结果表明,传感器能够在28~800℃的温度下和0~10 MPa的气压下稳定工作,测量范围内温度灵敏度可达17.4 nm/℃,压力灵敏度随温度增加而降低,在28℃时可达1460.5 nm/MPa.     

XPS and resistive studies on thin films of a copper(II)‐based coordination polymer deposited on functionalized interdigital electrodes

A symmetrical 2‐thiopyrimidine based molecule with an expanded π‐electron system is synthesized and used to form a self‐assembled monolayer (SAM) on gold surfaces. Utilizing chemical vapor deposition a monolayer of (3‐mercaptopropyl)triethoxysilane is formed on silicon dioxide substrates. Both of these SAM coated substrates are characterized by X‐ray photoelectron spectroscopy and the growth of a coordination polymer built up from 5,5′‐(ethyne‐1,2‐diyl)bis(2‐hydroxyacetophenone) and copper(II) on dual SAM coated transducers is studied. After the deposition procedure on interdigital electrodes the electrical properties of the polymer are investigated performing resistive measurements. A significant change of the resistance, which depends on the surrounding atmosphere, proves the sensing behavior of the synthesized coordination polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 335–344