Direct Toner Printing: A Versatile Technology for Easy Fabrication of Flexible Miniaturized Electrodes

We reported here three simple, low cost and easy to accomplish strategies for the fabrication of microelectrodes and other conductive patterns using ordinary office laser‐printers. In this work, toner patterns were directly printed onto the flexible substrate, acting as a mask to create the intended conductive design. To highlight the versatility of such technology, toner‐printed patterns were employed in two diverse ways: one in which the patterned toner had the exact design of the electrode and other employing a reverse toner‐printed pattern. The first one was used for the adaptation of the well‐known printed circuit board (PCB) fabrication technique, but using direct toner printing (DTP) in an already conductive flexible substrate. The second was employed for the two remaining strategies: one based on the deposition of conductive film, followed by lift‐off process; and another based on drop‐casting of a conductive ink into the formed toner cavities, followed by thermal cure. As proof‐of‐concept, all three DTP strategies were used for the fabrication of miniaturized gold electrodes in polyimide substrate, and electrochemical performance of each obtained electrode was evaluated by cyclic voltammetry. Insights about DTP technology, alignment issues, advantages, limitations and resolution of each presented approach were provided. Finally, direct toner printing showed to be a simple, affordable and quite promising technology for the fabrication of low cost point‐of‐care electrochemical devices using flexible platforms.     

Determination of direct orange 8 in effluent using a polypyrrole modified electrode

Electrochemical studies of direct orange 8 were carried out with a bare glassy carbon electrode (GCE) and a polypyrrole-coated GCE in aqueous acetonitrile medium using voltammetric techniques. One reversible couple around 0.3?V due to the redox reaction of the phenol group, one reduction peak around ?0.4?V due to reduction of the azo group and one oxidation peak around 1.0?V due to oxidation of the amino group were observed. Chronocoulometric studies revealed dye adsorption on the GCE. A square-wave stripping method was developed for the determination of the dye at pH 13.0, and a linear calibration equation obtained. The reproducibility in the measurement of peak currents was confirmed from the RSD value 2.8% at 0.001?mg?mL^?1 concentration. A comparison of the stripping voltammetric method with the UV-Vis spectrophotometric method was made. The determination limits are wider and the RSD value is lower in the stripping voltammetric method. The concentration of the dye present in dye effluent was determined using this method.     

Thermal degradation mechanism of flame retarded epoxy resins with a DOPO-substitued organophosphorus oligomer by TG-FTIR and DP-MS

A novel phosphorus-containing oligomeric flame retardant, poly(DOPO substituted hydroxyphenyl methanol pentaerythritol diphosphonate) (PDPDP) was synthesized and applied to flame retarded epoxy resins. The thermal degradation behaviors of flame retarded epoxy composites with PDPDP were investigated by thermogravimetric analysis (TGA), thermogravimetric analysis/infrared spectrometry (TG-FTIR) and direct pyrolysis-mass spectrometry (DP-MS) techniques. The identification of pyrolysis fragment ions provided insight into the flame retardant mechanism. The results showed that the mass loss rate of the EP/PDPDP composites was clearly lower than pure EP when the temperature was higher than 300 °C in air or nitrogen atmosphere. The results also suggested that the main decomposition fragment ions of the EP/PDPDP composite were H₂O, CO₂, CO, benzene, and phenol. The incorporation of PDPDP can reduce the release of combustible gas and induce the formation of char layer, hence the fire potential hazard was reduced.     

In‐line preconcentration capillary zone electrophoresis for the analysis of haloacetic acids in water

Two in‐line enrichment procedures (large volume sample stacking (LVSS) and field amplified sample injection (FASI)) have been evaluated for the CZE analysis of haloacetic acids (HAAs) in drinking water. For LVSS, separation on normal polarity using 20 mM acetic acid–ammonium acetate (pH 5.5) containing 20% ACN as BGE was required. For FASI, the optimum conditions were 25 s hydrodynamic injection (3.5 kPa) of a water plug followed by 25 s electrokinetic injection (?10 kV) of the sample, and 200 mM formic acid–ammonium formate buffer at pH 3.0 as BGE. For both FASI and LVSS methods, linear calibration curves (r²>0.992), limit of detection on standards prepared in Milli‐Q water (49.1–200 μg/L for LVSS and 4.2–48 μg/L for FASI), and both run‐to‐run and day‐to‐day precisions (RSD values up to 15.8% for concentration) were established. Due to the higher sensitive enhancement (up to 310‐fold) achieved with FASI‐CZE, this method was selected for the analysis of HAAs in drinking water. However, for an optimal FASI application sample salinity was removed by SPE using Oasis WAX cartridges. With SPE‐FASI‐CZE, method detection limits in the range 0.05–0.8 μg/L were obtained, with recoveries, in general, higher than 90% (around 65% for monochloroacetic and monobromoacetic acids). The applicability of the SPE‐FASI‐CZE method was evaluated by analyzing drinking tap water from Barcelona where seven HAAs were found at concentration levels between 3 and 13 μg/L.     

Direct Electrochemistry and Electrocatalysis of Myoglobin with Ionic Liquid through Multilayers Film on Carbon Ionic Liquid Electrode

Multilayers of myoglobin (Mb) with ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF₄) was assembled on carbon ionic liquid electrode (CILE) based on the electrostatic attraction between the negatively charged Mb and the positively charged imidazolium ion of IL. The CILE was fabricated with 1‐ethyl‐3‐methylimidazolium ethylsulfate ([EMIM]EtOSO₃) as the modifier, which exhibited imidazolium ion on the electrode surface. Then Mb molecules were assembled on the surface of CILE step‐by‐step to get a {IL/Mb}_n multilayer film modified electrode. UV‐Vis adsorption and FT‐IR spectra indicated that Mb remained its native structure in the IL matrix. In deaerated phosphate buffer solution (pH 7.0) a pair of well‐defined quasi‐reversible redox peaks appeared with the apparent formal potential (E^0′) as ‐0.212 V (vs. SCE), which was the characteristic of Mb heme Fe(III)/Fe(II) redox couples. The results indicated that the direct electron transfer of Mb was realized on the modified electrode. The {IL/Mb}_n/CILE displayed excellent electrocatalytic ability to the trichloroacetic acid reduction in the concentration range from 2.0 to 22.0 mmol/L with the detection limit of 0.6 mmol/L (3σ). The proposed method provides a new platform to fabricate the third generation biosensor based on the self‐assembly of redox protein with ILs.     

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

The rate constants of the hydrogen abstraction reactions of CF₃CHFCF₃ + H (R1) and CF₃CF₂CHF₂ + H (R2) have been calculated by means of the dual-level direct dynamics method. Optimized geometries and frequencies of stationary points and extra points along the minimum-energy path (MEP) are obtained at the MPW1K/6-311+G(d,p) level, and the classical energetic information is further corrected with the interpolated single-point energy (ISPE) approach by the G3(MP2) level of theory. Using the canonical variational transition state theory (CVT) with small-curvature tunneling corrections (SCT), the rate constants are evaluated over a wide temperature range of 200-2000 K. The calculated CVT/SCT rate constants are in good agreement with available experimental values. It is found that the variational effect is very small and almost negligible over the whole temperature region. However, the small-curvature tunneling correction plays an important role in the lower temperature range. Furthermore, the heats of formation of species CF₃CF₂CHF₂ (SC₁ or SC₂) and CF₃CF₂CF₂ are studied using isodesmic reactions to further elucidate the thermodynamic properties.     

Direct detection of nanoparticles and components in smoke by time-of-flight mass spectrometry with soft plasma ionization

A new system combining a soft plasma ionization (SPI) source with a time-of-flight mass spectrometer (TOFMS) has been successfully developed and applied to direct and on-line analysis of nanoparticles in smoke generated during combustion of mosquito coils with no sample preparation. The mass spectra of nanoparticles in smoke were examined in conjunction with the effects of species, pressure and current of the SPI discharge on fragmentation. The results indicated that a maximum mass of m/z 1576 was detectable when the following optima SPI conditions were satisfied: a He gas pressure of 1000 Pa with an air pressure of 1600 Pa and a discharge current of 110 mA. Furthermore, considering the results for emission spectra we suppose an ionization mechanism of SPI in which excitation and ionization of nitrogen molecule is promoted by the presence of He gas, leading to promote the smoke sample ionization. The mass spectrum of nanoparticles showed specific patterns of a peak interval of 74 which were assigned to triacetylene (1,3,5-hexatriyne). The most abundant peak in the mass spectrum, at m/z 452, was assigned to triacontanoic acid.     

Direct Electrochemistry and Application in Electrocatalysis of Hemoglobin in a Polyacrylic Resin‐Gold Colloid Nanocomposite Film

A novel nanocomposite integrating the good biocompatibility of polyacrylic resin nanoparticles (PAR) and the good conductivity of colloidal gold nanoparticles was proposed to construct the matrix for the immobilization of hemoglobin (Hb) on the surface of a glassy carbon electrode (GCE). UV‐vis spectra demonstrated that Hb preserved its native structure after being entrapped into the composite film. The direct electrochemistry of hemoglobin (Hb) in this nanocomposite films showed a pair of well‐defined and quasi‐reversible cyclic voltammetric peaks with a formal potential of ?0.307 mV and a constant electron transfer rate of 2.51±0.2 s^?1. The resultant amperometric biosensor showed fast responses to the analytes with excellent detection limits of 0.2 µM for H₂O₂ and 0.89 µM for TCA (S/N=3), and high sensitivity of 1108.6 for H₂O₂ and 77.14 mA cm^?2 M^?1 for TCA, respectively. The linear current response was found in the range from 0.59 to 7.3 µM (R²=0.9996) for H₂O₂ and from 5 to 85 µM (R²=0.9996) for TCA, while the superior apparent Michaelis–Menten constant was 0.012 mM for H₂O₂ and 0.536 mM for TCA, respectively. Therefore, the PAR‐Au‐Hb nanocomposite as a novel matrix opens up a possibility for further study on the direct electrochemistry of other proteins.     

鼓风炉渣中氧化钙的测定方法改进

在参照DHF83-B多元素快速分析仪法测定炉渣中氧化钙的基础上,对鼓风炉渣中氧化钙的测定方法进行了改进。用盐酸（1+1）溶样,三乙醇胺掩蔽残留的铁、铝、锰等元素,以钙指示剂作指示剂,于pH值大于12时用EDTA标准溶液滴定氧化钙。EDTA滴定法分析结果的相对标准偏差RSD为2.82%,与DHF83-B多元素快速分析仪法比较,其结果基本一致。该方法具有准确度好、快速简便等优点,适合用于冶炼炉渣中氧化钙含量的测定。     

大孔炭载Pd催化剂对甲酸氧化的电催化性能

用X射线能量色散谱(EDS)、X射线衍射(XRD)谱、拉曼光谱和电化学技术研究和比较了直接甲酸燃料电池(DFAFC)中Vulcan XC-72炭黑载Pd (Pd/XC)和大孔炭载Pd (Pd/MC)催化剂对甲酸氧化的电催化性能. 循环伏安曲线测量表明甲酸在Pd/XC和Pd/MC催化剂电极上主要氧化峰的峰电位基本相同, 在0.15 V左右, 但在Pd/MC催化剂电极上的峰电流密度比在Pd/XC催化剂上的大30%左右. 计时电流曲线测量表明, 在6000 s时, 在Pd/MC催化剂电极上的峰电流密度比在Pd/XC催化剂上的大38%左右, 这些结果说明Pd/MC催化剂对甲酸氧化的电催化活性和稳定性要好于Pd/XC催化剂. 由于Pd/MC和Pd/XC催化剂的Pd粒子平均粒径和相对结晶度相似, 因此, Pd/MC催化剂电催化性能好的原因只能归结于MC大的孔径和高的石墨化程度引起的高电导率.