Synthesis, characterization and electrochemical properties of 4.8 V LiNi0.5Mn1.5O4 cathode material in lithium-ion batteries

In this work the synthesis of a nickel doped cubic manganese spinel has been studied for application as cathode material in secondary lithium batteries. Six different experimental approaches have been tested in order to carry out a screening of the various possible synthetic routes. The used synthetic strategies were wet chemistry (WC), solid state (SS), combustion synthesis (CS), cellulose-based sol-gel synthesis (SG-C), ascorbic acid-based sol-gel synthesis (SG-AA) and resorcinol/formaldehyde-based sol-gel synthesis (SG-RF). The goal of our study is to obtain insights about how the synthesis conditions can be modified in order to achieve a material with improved electrochemical performances in such devices, especially in high current operating regimes. The synthesized materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), atomic absorption, inductively coupled plasma (ICP-MS) atomic emission spectroscopy, surface area measurements and tested as high voltage cathodes in Li-ion electrochemical devices.     

Potential of ionic liquids for VOC absorption and biodegradation in multiphase systems

This work aims to evaluate the feasibility of using imidazolium ionic liquids (ILs) in the design of multiphase bioreactors for the removal of volatile organic compounds (VOCs). The IL affinity for three model VOCs (dimethyl sulfide, dimethyl disulfide and toluene) was evaluated by means of the dimensionless partition coefficient (K). It was observed that ILs showed K values comparable to typical liquid solvents used in multiphase bioreactors for VOC biodegradation (K values ranged from 0.009 to 0.011, 0.0012 to 0.0013 and 0.00061 to 0.00096 for dimethyl sulfide, dimethyl disulfide and toluene, respectively). Toxicity tests showed that both ILs at concentrations of 5% and 10% (v/v) inhibited the glucose uptake of an activated sludge during approximately 24 h. After such lag period, the microorganisms were able to recover its metabolic activity. However, VOC biodegradation experiments showed that ILs at 5% (v/v) were toxic for the activated sludge and a toxic synergistic effect of the IL–VOC combination likely occurred. After acclimation to the target VOCs, only the toluene biodegradation capacity was significantly increased in the presence of ILs. These toxic effects represent a key drawback for the potential of IL-based multiphase systems devoted to VOC biodegradation. Therefore, this study suggests that microbial acclimation only to the VOCs is not enough to get an efficient biodegradation in multiphase systems including ILs as non-aqueous phases.     

Proton conductors of cerium pyrophosphate for intermediate temperature fuel cell

The crystal structure and proton conductivity of cerium pyrophosphate are investigated to explore its potential electrolyte applications for intermediate temperature fuel cell. Among the CeP₂O₇ thin plates, which are sintered at 300–900 °C, the 450 °C CeP₂O₇ sample exhibits superior proton conductivity under humidified conditions. Its conductivity, measured with impedance spectroscopy, is higher than 10⁻² S cm⁻¹ in the intermediate temperature range, with a maximum value 3.0 × 10⁻² S cm⁻¹ at 180 °C. When 10 mol% Mg is doped on the Ce site of CeP₂O₇, the maximum conductivity is raised to 4.0 × 10⁻² S cm⁻¹ at 200 °C. The Mg doping not only raises the conductivity, but also shifts and widens its temperature window for electrolyte applications. Ce_0.9Mg_0.1P₂O₇ is considered a more appropriate composition, with conductivity >10⁻² S cm⁻¹ between 160 and 280 °C. Accordingly, a hydrogen–air cell is built with the Ce_0.9Mg_0.1P₂O₇ electrolyte and its performance is measured. The fuel cell generates electricity up to 122 mA cm⁻² at 0.33 V using 50% H₂ at 240 °C.     

One step synthesis of lamellar R-3m LiCoO2 thin films by an electrochemical–hydrothermal method

In this study, we report the synthesis of lamellar R-3m LiCoO₂ thin films electrodes for lithium rechargeable batteries by a single step method based on an electrochemical–hydrothermal synthesis in a concentrated LiOH solution with a cobalt salt. This process combines the effect of temperature (between 150 °C and 200 °C), pressure and galvanostatic current. The obtained films were not annealed after the electrochemical–hydrothermal synthesis.For the first time, the theoretical study of the potential–pH diagram of cobalt was carried out at high temperature and high concentration. These calculations show that a pH value higher than 12 is necessary to avoid the direct precipitation of cobalt hydroxide Co(OH)₂ inside the solution. An improvement of the soluble species stability with an increase of the temperature and a decrease of the cobalt concentration is predicted. The influence of the deposition conditions (temperature and concentration) at a constant current density was experimentally studied. X-ray diffraction (XRD) shows the formation of well-crystallized LiCoO₂ thin films. Raman spectroscopy confirmed the achievement of the electrochemically active R-3m LiCoO₂ phase without any trace of the Fd3m phase at temperatures as low as 150 °C. Electrochemical measurements demonstrate good performances of the material synthesized between 150 °C and 200 °C with better capacity retention at higher temperature.     

Towards the detection of human papillomavirus infection by a reagentless electrochemical peptide biosensor

In the present work, we report first results about a technology using a conjugated copolymer poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-2-carboxyethyl-1,4-naphthoquinone) acting both as immobilizing and transducing element for reagentless immunosensor, and its application for the detection of HPV infection. It was shown that the reagentless immunosensor was able to detect the interaction between antigenic peptide L1 from HPV-16 major capsid protein, a dominant epitope involved in viral infection as well as in prophylactic vaccine, and the relevant antibody.     

Characterization of multi-walled carbon nanotube electrodes functionalized by electropolymerized tris(pyrrole-ether bipyridine) ruthenium (II)

We synthesized new electropolymerizable [Ru(bpy)_nL_m](PF₆)₂ (L = 4,4 bis(3-pyrrol-1-ylpropyloxy)bipyridyl) derivatives. The introduction of electron donating ether groups in the bipyridine ligand induced a negative shift of the Ru(III)/(II) redox couple. The electrochemical behavior of complex Ru1 (n = 2, m = 1) and complex Ru2 (n = 0, m = 3) were compared using platinum and Multi-Walled Carbon Nanotube (MWCNT) electrode. Higher polymerization yields and surface concentrations were obtained at MWCNT electrodes. Furthermore, MWCNT electrodes increase polymer permeability and decrease the charge trapping phenomenon involved in the oxidation and reduction of the polypyrrolic skeleton of the Ru(II) functionalized polymers.     

果蔬比热容的影响因素

食品的比热容在其加工、流通、保鲜环节起着重要的作用。利用同步法测定35种果蔬的比热容及其可溶性固形物含量、密度和含水率,并确定其相关性。结果表明：果蔬比热容随着温度的增大而缓慢增大,并且随着温度的升高,比热容的增长率逐渐减小直至不再变化。果蔬含水率和可溶性固形物含量与比热容的相关性分别达到极显著水平;果蔬密度与比热容的相关性没有达到显著水平。果蔬比热容随着果蔬含水率增加呈递增趋势,而可溶性固形物含量大的果蔬具有较小的比热容。     

一种单相串联混合电力有源滤波器的研究

文中对串联混合电力滤波器抑制谐波的原理进行了分析。为了检测单项系统的谐波电流,提出一种基于虚拟三相法和瞬时无功理论的谐波检测方法,并且对串联滤波逆变器的直流侧电压的控制进行了讨论。仿真结果证明了其有效性。     

Compact 2.5 Gb/s Burst‐Mode Receiver with Optimum APD Gain for XG‐PON1 and GPON Applications

This letter presents a compact 2.5 Gb/s burst‐mode receiver using the first reported monolithic amplifier IC developed with 0.25 …m SiGe BiCMOS technology. With optimum avalanche photodiode gain, the receiver module can obtain a fast response, high sensitivity and wide dynamic range, satisfying the overhead timing and various power specifications for a 2.5 Gb/s next‐generation passive optical network (PON), as well as a legacy 1.25 Gb/s PON in the upstream.     

Catalytic wall reactor: Catalytic coatings of stainless steel by VOx/TiO2 and Co/SiO2 catalysts

Catalytic wall (structured) reactors and structured supports are suitable to study the catalytic properties of nanosized materials. The coating of metallic (aluminum and stainless steel) plates by thin layers of active phase is presented in two cases, VO_x/TiO₂ and Co/SiO₂, catalysts used in the oxidative dehydrogenation (ODH) of propane and in Fischer–Tropsch synthesis (FTS) of clean fuels, respectively. The preparation of coated plates and their characterisation by various methods of physicochemical analysis are described. Both chemical and physical methods were used for coating. VO_x/TiO₂ layers were obtained by grafting of Ti (on Al or stainless-steel plates) and V (on TiO₂) alkoxides and use of sol–gel media or suspension. A silica primer was deposited (on stainless-steel plate) by plasma-assisted chemical vapour deposition (PACVD) onto which Co oxide and silica were coprecipitated from sol–gel. The catalytic experiments in the respective reactions were carried out in special plate reactors and compared with those of catalytic powders. The study shows that the coating of a metallic substrate by a catalyst is not straightforward and requires specific studies dealing with both chemistry (chemical affinity between substrate and catalytic layers) and catalytic engineering (catalytic performance in taylor-made reactors).