Development of a Chitosan/Nickel Phthalocyanine Composite Based Conductometric Micro-sensor for Methanol Detection

Thin-film composite of chitosan/nickel phthalocyanine (NiPc) was electrochemically deposited on the fingers of interdigitated gold electrodes, applying chronoamperometric polymerization technique. The presence of crystallized NiPc in the chitosan was confirmed by EDX and FTIR analysis. Acetone, ethanol, and methanol gas-sensing properties of the films prepared at optimum conditions were studied at atmospheric temperature, through differential measurements at an optimized frequency of 10 kHz, using a lock-in amplifier. The conductometric sensor presents the highest sensitivity of 60.2 μS.cm⁻¹(v/v) for methanol and 700 ppm as the limit of detection. For validation, the methanol content of a commercial rubbing alcohol was determined.     

PSO-LSSVM对LIBS定量分析精度的提高

针对土壤定量分析受基体效应影响大，LIBS定量分析精度不佳等问题，采用粒子群算法对LSSVM进行优化，提高模型的精确度。选取Pb Ⅰ 405.78 nm和Cr Ⅰ 425.44 nm作为分析谱线进行分析。采集十二个不同浓度样品的特征光谱，每个浓度样品在不同点采集20组数据，将其中17组数据设为训练集，3组数据设为预测集，用LSSVM和PSO-LSSVM两种方法建立定标模型。对比两种模型的拟合相关系数（R2）、训练集均方根误差（RMSEC）和预测集均方根误差(RMSEP)。由于自吸收效应的影响，随着浓度的增加，预测值逐渐低于实际值，LSSVM定标模型的拟合程度较低，无法达到实验要求，模型性能有待提高。利用粒子群算法对LSSVM的模型参数惩罚系数和核函数参数进行优化，得到最佳的参数组合，Pb元素为(8 096.8, 138.865 7)，Cr元素为(4 908.6, 393.563 5)，用最佳的参数组合构建LSSVM的定标模型。相比于LSSVM，PSO-LSSVM定标模型的精确度更高，Pb和Cr元素的R2提高到了0.982 8和0.985 0，拟合效果明显提升。Pb和Cr元素的训练集均方根误差由0.026 0 Wt%和0.027 2 Wt%下降到0.022 4 Wt%和0.019 1 Wt%，预测集均方根误差由0.101 8 Wt%和0.078 8 Wt% 下降到0.045 8 Wt%和0.042 0 Wt%，模型的稳定性进一步提高。说明PSO-LSSVM算法能够更好地降低土壤基体效应和自吸收效应带来的影响，提高分析结果的精确度与稳定性。     

对称向量拟均衡问题有效解的存在性

利用标量化方法建立对称向量拟均衡问题有效解的存在性定理。作为标量化方法的应用，利用这一方法得到向量变分不等式和拟向量变分不等式有效解的存在性定理。     

Multi-emissive 1D Cd(II) polymers with a biphenyl bridged bisazamacrocycle for ratiometric discrimination of nitroaromatics and selective visual detection of picric acid

Three one-dimensional ladder-like coordination polymers consisting of Cd₆ metalloring as the building unit, {[Cd₄LCl₄]·3H₂O}_n ( 1 ), {[Cd₃L(ClO₄)(H₂O)]ClO₄·3H₂O}_n ( 2 ), and {[Cd₆(L)₂(NO₃)₂(CH₃OH)(H₂O)](NO₃)₂·2CH₃OH·5H₂O}_n ( 3 ), were solvothermally constructed from a carboxylic functionalized bisazamacrocyclic ligand 4,4′-bis((4,7-bis(2-carboxyethyl)-1,4,7-triazacyclonon-1-yl)methyl)-1,1′-biphenyl (H₄L). These compounds dispersed in ethanol show the multiple emissions originating from the monomeric and intramolecularly overlapping biphenyl moieties which could be sensitively quenched by picric acid (PA) and 4-nitrophenol (4-NP) through the effective fluorescence resonance energy transfer process. The differential fluorescent responses of each compound on exposure to PA and 4-NP individually make the convenient ratiometric discrimination of two analytes based on the fluorescent intensity ratio (I₃₂₀/I₃₆₀) attainable, and 1 and 2 as ratiometric chemosensors for PA present a broad linear detection range from 4 to 300 μM with detection limits of 0.84 and 0.93 μM, respectively. Furthermore, the blue light emission of 1 under an ultraviolet lamp could be selectively quenched by PA even in the presence of all other interfering nitroaromatic pollutants, which empowers the fast visual detection of PA by naked eye.     

Semi-concurrent vector fields in Finsler geometry

In the present paper, we give an answer to a question which is closely related to doubly warped product of Finsler metrics: ‘‘For each n, is there an n-dimensional Finsler manifold $(M,F)$, admitting a non-constant smooth function f on M such that $\frac{\partial f}{\partial x^i}\frac{\partial g^{ij}}{\partial y^k}=0$?”. We relate the preceding mentioned condition to different concepts appeared and studied in Finsler geometry. We introduce and investigate the notion of a semi concurrent vector field on a Finsler manifold. We show that some special Finsler manifolds admitting such vector fields turn out to be Riemannian. We prove that Tachibana's characterization of Finsler manifolds admitting a concurrent vector field leads to Riemannian metrics. Various examples for conic Finsler spaces that admit semi-concurrent vector field are presented.     

A stable pillared metal–organic framework constructed by H4TCPP ligand as luminescent sensor for selective detection of TNP and Fe3+ ions

A novel luminescent metal–organic framework ( Zn‐TCPP/BPY ) with pillared structure based on 2,3,5,6‐tetrakis(4‐carboxyphenyl)pyrazine (H₄TCPP) and 4,4′‐bipyridine (BPY) has been designed and synthesized through a solvothermal reaction. The [Zn₂(COO)₄] paddlewheel units are linked by TCPP^4? ligands to form two‐dimensional layers and further connected by BPY ligands as pillars to construct the twofold interpenetrating three‐dimensional framework. Interestingly, Zn‐TCPP/BPY possesses outstanding stability in organic solvents and water as well as maintains its structural rigidity in aqueous solutions of different pH values (3–12). After activation, Zn‐TCPP/BPY possesses permanent porosity with Brunauer–Emmett–Teller surface area of 630 m² g^–1. Remarkably, Zn‐TCPP/BPY displays excellent fluorescent property in virtue of the aggregation‐induced emission effect of the H₄TCPP ligand, which can be highly active and quenched by small amounts of 2,4,6‐trinitrophenol (TNP) and Fe³⁺ ions. Furthermore, the detection effect of Zn‐TCPP/BPY remains basically the same even after five cycles. The excellent stability, high sensitivity, and recyclability of Zn‐TCPP/BPY make it an outstanding chemical sensor for detecting TNP and Fe³⁺ ions.     

Tunable and highly sensitive temperature sensor based on graphene photonic crystal fiber

Optical fiber temperature sensors have been widely employed in enormous areas ranging from electric power industry, medical treatment, ocean dynamics to aerospace. Recently, graphene optical fiber temperature sensors attract tremendous attention for their merits of simple structure and direct power detecting ability. However, these sensors based on transfer techniques still have limitations in the relatively low sensitivity or distortion of the transmission characteristics, due to the unsuitable Fermi level of graphene and the destruction of fiber structure, respectively. Here, we propose a tunable and highly sensitive temperature sensor based on graphene photonic crystal fiber (Gr-PCF) with the non-destructive integration of graphene into the holes of PCF. This hybrid structure promises the intact fiber structure and transmission mode, which efficiently enhances the temperature detection ability of graphene. From our simulation, we find that the temperature sensitivity can be electrically tuned over four orders of magnitude and achieve up to ～ 3.34×10^-3 dB/(cm·℃) when the graphene Fermi level is ～ 35 meV higher than half the incident photon energy. Additionally, this sensitivity can be further improved by ～ 10 times through optimizing the PCF structure (such as the fiber hole diameter) to enhance the light-matter interaction. Our results provide a new way for the design of the highly sensitive temperature sensors and broaden applications in all-fiber optoelectronic devices.     

基于气体浓度定量的嗅觉刺激器优化设计

现有的基于磁共振测量的嗅觉刺激器，通过调节嗅剂液体浓度的方法可以实现不同浓度的嗅觉刺激，但随着实验进行，受到嗅剂挥发以及实验环境（温度、湿度、气流量）变化的影响，很难确保输送至鼻腔的嗅剂气体浓度的稳定性，进而影响实验结果的准确性．本研究对本实验室前期开发的嗅觉刺激装置进行改进，实现了气体浓度精确定量．改进后的嗅觉刺激器主要分为三个部分：控制系统、反馈系统和气路系统．控制系统主要实现气路系统的送气控制和嗅剂气体浓度调节；反馈系统则负责对气体浓度进行测量；气路系统则在原有基础上添加活性炭装置，降低无关因素干扰．装置改进之后，不同气路切换时间为75.2 ms，比原装置减少了1 s，有效提高刺激精度．实验结果显示，气体浓度调节前，300 s内乙醇、吡啶、乙酸戊酯嗅剂气体浓度分别下降6.7%、71.4%、79.2%，嗅剂气体浓度短时间内发生较大改变．加入气体浓度调节功能后，当气体浓度下降至目标浓度的90%时，可通过调节气泵电压改变嗅剂气流与空气气流比例，从而调节嗅剂气体浓度至目标值，其中吡啶、乙酸戊酯用时13 s．