An anionic chromogenic sensor based on protonated Reichardt’s pyridiniophenolate

An anionic sensor based on Reichardt’s betaine is described here. The dye is blue-green in chloroform but becomes colorless under protonation. Increasing amounts of different anions were added into the solution of the protonated dye. The addition of F⁻ and caused the reappearance of the original blue-green color, while the addition of I⁻ made the solution of the protonated dye yellow. The observations are discussed based on the fact that F⁻ and can act as bases accepting a proton from the protonated dye and also in relation to the formation of a complex between the protonated dye and iodide.     

Electrochemical Studies of Thiol Self‐Assembled Monolayers at a Heated Gold‐Wire Microelectrode

Mercaptoundecanoic acid (MUA) and glutathione (GSH) self‐assembled monolayers were prepared on gold‐ wire microelectrode. Cyclic voltammetry was used to investigate the influence of temperature on electrochemical behaviors of Fe(CN)₆^3?/4? and Ru(NH₃)₆^3+/2+ at these SAMs modified electrodes in aqueous solution. It is found that temperature shows great influence on electron transfer (ET) and mass transport (MT) for the two SAMs modified electrodes and the influence of temperature depends on the charge properties of the redox couples and terminal groups of SAMs and the structure of the monolayer on gold surface. The temperature can greatly increase MT rate of Fe(CN)₆^3?/4? at both MUA and GSH modified electrodes. However, the increased MT rate doesn't have any effect on the CV's for Fe(CN)₆^3?/4? /MUA system. For Ru(NH₃)₆^3+/2+ , temperature can greatly improve the electrochemical reaction in both MUA and GSH modified electrodes, which is ascribed to temperature‐induced diffusion and convection and the electrostatic interaction between Ru(NH₃)₆^3+/2+ and negatively charged carboxyl groups on the electrode surface.     

Copper(II) ion sensor based on electropolymerized undoped conducting polymers

A solid state copper(II) ion sensor is reported based on the application of electropolymerized undoped (neutral) polycarbazole (PCz) and polyindole (PIn) modified electrodes. The new sensor shows high selectivity to Cu²⁺ ions with a detection limit of 10^–5 M. PCz and PIn are formed respectively by the anodic oxidation of 50 mM carbazole and 5 mM indole monomers in dichloromethane containing 0.1 M tetrabutylammonium perchlorate on a platinum electrode using a single compartment cell. Potentiostatic polymerization of both the monomers are carried out at 1.3 V and 1.0 V vs. Ag/AgCl, respectively. Perchlorate ions were electrochemically removed from the polymer films by applying – 0.2 V vs. Ag/AgCl. Polymer-coated electrodes are incubated in 1 M KCl solution for 8 h followed by incubation in distilled water for 2 h before using as a metal ion sensor. The undoped PCz and PIn electrodes were found to be highly selective and sensitive for Cu²⁺ ions with little selectivity for Pb²⁺ and negligible response towards Ag⁺, Hg²⁺, Cu⁺, Ni²⁺, Co²⁺, Fe²⁺, Fe³⁺ or Zn²⁺. Potentiometric responses for Cu²⁺ ions are recorded for both the sensor electrodes together with a double-junction Ag/AgCl reference electrode. Calibration curves for Cu²⁺ are reported for both ion sensors. The polymer-modified electrodes were found to be stable for several weeks. Electronic Publication     

Integrated chemical sensor array platform based on a light emitting diode, xerogel-derived sensor elements, and high-speed pin printing

We report a new, solid-state, integrated optical array sensor platform. By using pin printing technology in concert with sol-gel-processing methods, we form discrete xerogel-based microsensor elements that are on the order of 100 μm in diameter and 1 μm thick directly on the face of a light emitting diode (LED). The LED serves as the light source to excite chemically responsive luminophores sequestered within the doped xerogel microsensors and the analyte-dependent emission from within the doped xerogel is detected with a charge coupled device (CCD). We overcome the problem of background illumination from the LED reaching the CCD and the associated biasing that results by coating the LED first with a thin layer of blue paint. The thin paint layer serves as an optical filter, knocking out the LEDs red-edge spectral tail. The problem of the spatially-dependent fluence across the LED face is solved entirely by performing ratiometric measurements. We illustrate the performance of the new sensor scheme by forming an array of 100 discrete O₂-responsive sensing elements on the face of a single LED. The combination of pin printing with an integrated sensor and light source platform results in a rapid method of forming (∼1 s per sensor element) reusable sensor arrays. The entire sensor array can be calibrated using just one sensor element. Array-to-array reproducibly is <8%. Arrays can be formed using single or multiple pins with indistinguishable analytical performance.     

Fourier transform spectroscopy using image sensors

Multichannel Fourier transform spectrometers utilizing image sensing devices are reviewed along with the instrumental design concepts. Although the idea itself is fairly simple, a photographic plate in holographic spectroscopy is replaced by an image sensor, there are stringent requirements to be satisfied in order to realize the system for field use. Mainly two types of the instrument, which are characterized by the Sagnac common-path interferometer and the polarization interferometer optics, respectively, are described with regard to their system performances. Examples of the system operation introduced show that Fourier transform spectrometers without mechanical moving parts play an important role in a variety of spectroscopic applications under severe surroundings. In a summary, methods for the resolution enhancement and comments on the signal-to-noise ratio are also included.     

CAHN－2000磁天平的调试与数据处理系统的研制

叙述了ＣＡＨＮ－２０００磁天平（美国）调试过程中如何解决液氮温区的测试，自制了磁天平与计算机的接口，编写了数据采集、处理和控制等高原 软件，节省了几万美元，部分指标超过原配套水平，三年来仪器在对国同外开放过程中，液氮温区的工作一直正常，实测了上千个样品，提供的数据已撰写数十篇文章在国内外刊物上发表。由此说明，要充分发挥进口仪器的使用效率，必须对仪器的工作原理、结构特点有透乇的了解，同时要有相当的自     

基于定向纳米碳管气体放电的气敏传感器研究

介绍了一种基于定向纳米碳管的气敏传感器,以生长定向纳米碳管的氧化铝模板作为阳极,铝板作为阴极,利用纳米碳管的尖端发射效应,在较低的电压下使气体产生放电现象。通过对纳米碳管在气体中击穿电压和放电电流的测量,实现对气体的定性定量检测。同时纳米碳管气敏传感器还具有体积小、灵敏度高、稳定性好、响应速度快、在常温常压下即可进行检测等优点,具有较好的应用前景。     

溴化四-(4-N,N,N-二甲基,正庚烷基氨基苯基)卟啉钴的合成,L-B膜及其气敏、湿敏特性

卟啉和酞菁是一类大环共轭化合物,由于其结构和性能以及在生命科学中所起的作用,使得用L-B膜技术研究其结构和功能越来越引起人们的重视.自从Jones等发现原卟啉L-B膜具有较好的光导性以来,卟啉L-B膜的电导性和气体敏感特性相继有人进行过研究。发现卟啉铜L-B膜对二氧化氮有很高的敏感性,而且有良好的选择性.人工合成的     

The physical properties of pressure sensitive rubber composites

Nitrile butadiene rubber, NBR, structural foam of different apparent densities was obtained by using different concentrations of foaming agent, azodicarbonamide, ADC/K. The true stress-strain characteristics, in case of compression, of foamed samples after the application of cyclic stress-strain were measured. The effect of the cyclic stress-strain on strain energy density of ADC/K foaming agent-filled NBR rubber composites was studied. The mechanical parameters were found to depend on the foaming agent concentration and on the pre-cyclic fatigue number. Results also indicated that the strain energy decreased with filler concentration.The effects of the cyclic stress-strain on the conductivity of ADC/K foaming agent-filled NBR rubber composites were studied. The electrical properties were found to depend on the foaming agent concentration, the strain amplitude and the number of stress-strain cycles of pre-strain. This study was assisted by the current-voltage characteristics which were measured under the effect of different compression ratios: 0%, 5%, 10%, 15%, 20%, 25% and 30%. The free current carrier mobility and the equilibrium concentration of charge carriers in the conduction band were produced as functions of compressive strain. Results also indicate that there is a linear variation between pressure and conductivity for all samples, which means that these samples can be used as a pressure sensor.     

Analysis of sorption and bioavailability of different species of mercury on model soil components using XAS techniques and sensor bacteria

The present work studies the adsorption behaviour of mercury species on different soil components (montmorillonite, kaolinite and humic acid) spiked with CH₃HgCl and CH₃HgOH at different pH values, by using XAS techniques and bacterial mercury sensors in order to evaluate the availability of methyl mercury on soil components. The study details and discusses different aspects of the adsorption process, including sample preparation (with analysis of adsorbed methyl mercury by ICP-OES), the various adsorption conditions, and the characterization of spiked samples by XAS techniques performed at two synchrotron facilities (ESRF in Grenoble, France and HASYLAB in Hamburg, Germany), as well as bioavailability studies using mercury-specific sensor bacteria. Results show that XAS is a valuable qualitative technique that can be used to identify the bonding character of the Hg in mercury environment. The amount of methyl in mercury adsorbed to montmorillonite was pH-dependent while for all soil components studied, the bond character was not affected by pH. On the other hand, clays exhibited more ionic bonding character than humic acids did with methyl mercury. This interaction has a higher covalent character and so it is more stable for CH₃HgOH than for CH₃HgCl, due to the higher reactivity of the hydroxyl group arising from the possible formation of hydrogen bonds.The bioavailability of methyl mercury adsorbed to montmorillonite, kaolinite and humic acids was measured using recombinant luminescent sensor bacterium Escherichia coli MC1061 (pmerBR_BSluc). In case of contact exposure (suspension assays), the results showed that the bioavailability was higher than it was for exposure to particle-free extracts prepared from these suspensions. The highest bioavailability of methyl mercury was found in suspensions of montmorillonite (about 50% of the total amount), while the bioavailabilities of kaolinite and humic acids were five times lower (about 10%). The behaviour of methyl mercury in the presence of montmorillonite could be explained by the more ionic bonding character of this system, in contrast to the more covalent bonding character observed for humic acids. Thus, XAS techniques seem to provide promising tools for investigating the mechanisms behind the observed bioavailabilities of metals in various environmental matrices, an important topic in environmental toxicology.