Magnetically Induced Continuous CO2 Hydrogenation Using Composite Iron Carbide Nanoparticles of Exceptionally High Heating Power

The use of magnetic nanoparticles to convert electromagnetic energy into heat is known to be a key strategy for numerous biomedical applications but is also an approach of growing interest in the field of catalysis. The heating efficiency of magnetic nanoparticles is limited by the poor magnetic properties of most of them. Here we show that the new generation of iron carbide nanoparticles of controlled size and with over 80 % crystalline Fe_2.2C leads to exceptional heating properties, which are much better than the heating properties of currently available nanoparticles. Associated to catalytic metals (Ni, Ru), iron carbide nanoparticles submitted to magnetic excitation very efficiently catalyze CO₂ hydrogenation in a dedicated continuous‐flow reactor. Hence, we demonstrate that the concept of magnetically induced heterogeneous catalysis can be successfully applied to methanation of CO₂ and represents an approach of strategic interest in the context of intermittent energy storage and CO₂ recovery.     

A high-voltage lithium-ion battery prepared using a Sn-decorated reduced graphene oxide anode and a LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.5</Subscript>O<Subscript>4</Subscript> cathode

This paper describes the preparation and characterization of a high-voltage lithium-ion battery based on Sn-decorated reduced graphene oxide and LiNi_0.5Mn_1.5O₄ as the anode and cathode active materials, respectively. The Sn-decorated reduced graphene oxide is prepared using a microwave-assisted hydrothermal synthesis method followed by reduction at high temperature of a mixture of (C₆H₅)₂SnCl₂ and graphene oxide. The so-obtained anode material is characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and electron diffraction spectroscopy. The LiNi_0.5Mn_1.5O₄ is a commercially available product. The two materials are used to prepare composite electrodes, and their electrochemical properties are investigated by galvanostatic charge/discharge cycles at various current densities in lithium cells. The electrodes are then used to assemble a high-voltage lithium-ion cell, and the cell is tested to evaluate its performance as a function of discharge rate and cycle number.     

Gel-free IEF in a membrane-sealed multicompartment cell for proteome prefractionation

A minidevice for performing gel-free proteome prefractionation via conventional IEF in soluble carrier ampholyte buffers is reported here. It consists of a compact block of polyoxymethylene in which eight samples and two electrode chambers are machined. Each of the eight sample chambers can be filled with up to 120 microL of sample and has the following size: 7 mm width, 3 mm depth and 10 mm height. The anodic and cathodic compartments have the same width and height as the sample chambers, but with a depth of 6 mm, thus accepting up to 250 microL of electrodic solutions. Focusing is in general accomplished in 2 h with a voltage gradient of up to 1000 V (7 cm electrode distance). Easy fractionation and collection of the content of the eight chambers is achieved by simply pressing a rubber diaphragm against the edges of the thin walls separating each well, this automatically breaking liquid continuity. The performance of this device has been tested by subfractionating total cell lysates of a human cancer cell line (U2Os) and of Escherichia coli bacterial cells, and by analysing the content of each chamber by mono-dimensional SDS-PAGE and 2-D maps.     

Monitoring the traceability of the pH of a primary tetraborate buffer: comparison of results from primary and secondary apparatus

This paper reports evaluation of the behaviour of different combined glass electrodes applied to measurement of the pH of a primary, 0.01 mol kg⁻¹, tetraborate buffer. Measurements were first performed by use of a primary Harned cell (at 15, 25, and 37 °C); these results were then compared with those obtained for the same solution by use of three combined glass electrodes (25 °C) with different membranes and liquid-junction designs, calibrated by use of commercial pH-metric buffers. The pH of the same solution was also measured in terms of the molal concentration of hydrogen ions, using acid–base titration to evaluate the formal potential difference K of each cell at fixed ionic strength, I, adjusted by addition of KCl or Et₄NI (tetraethylammonium iodide). The reference value from primary measurement, paH = 9.171, was slightly closer to the mean value obtained by determination of concentration, rather than that obtained by direct measurement of activity; the differences were smaller than the extended uncertainty characteristics of the secondary measurements. The importance of evaluation of the ionic strength of the solution under study is emphasised. We verified that for tetraborate buffer slight modification of the value of I used to calculate γ _i (the activity coefficient of a single ion) in the calculation of paH from the acidity function at zero molality of chloride can significantly affect the reference value of the calibrator tool. This is true, in general, for low values of the ionic strength, such as those considered in this work; an approximate value of I can then cause distortions along the pH traceability chain. Application of the concepts of thermodynamics to this traceability chain is discussed.     

Effects of the exciting wavelength and viscosity on the photobehavior of 9- and 9,10-bromoanthracenes

The widely investigated photobehaviors of 9-bromo and 9,10-di-bromoanthracenes have been revisited here to clarify the competition among different relaxation paths of their lowest two electronic excited states. The results obtained show that these two molecules exhibit a parallel photobehavior, which depends on the excited electronic and vibronic transition, the medium viscosity, and the temperature. The first electronic state of either of these does not exhibit photochemistry in fluid solution or rigid matrices (80 K). The fluorescence emission occurs with a very low quantum yield (approximately 10(-2)) at room temperature but with a very high quantum yield (0.9 to approximately 1) at 80 K. When exciting in the second electronic transition, the fluorescence intensity is lower than when exciting in S1 at both room temperature and low temperature due to competition with the observed photocleavage of the C-Br bond. The reaction yield decreases as the temperature decreases and depends on the viscosity of the solvent; the higher the viscosity, the lower the observed yield of photochemistry. Temperature and viscosity effects are a consequence of the fact that the radicals produced by C-Br bond breakage cannot escape from the solvent cage and, moreover, quickly recombine within the cage giving the appearance that no photochemistry occurred. The presence of photochemistry in S(2) and its absence in S(1) is principally due to the fact that S(2) has a pi,sigma* character in the C-Br bond, whereas the S(1) state has its origin from a pi,pi* delocalized configuration.     

Romancing the "hidden proteome", Anno Domini two zero zero seven

The mechanism of action and properties of a solid-phase ligand library made of hexapeptides, for capturing the "hidden proteome", i.e. the low- and very low-abundance proteins constituting the vast majority of species in any proteome, be it a cell or tissue lysate or a biological fluid, are here reviewed. Mechanisms of adsorption are evaluated, as well as different protocols for en bloc or sequential elution of the captured polypeptides. Examples are given of capture of proteins from serum, human platelet extracts, bacterial extract and egg white. The increment in detection of low-abundance species appears to be of at least four-fold as compared with untreated samples. One particular aspect of this capture is the adsorption of a high proportion of small peptides (in the Mr 600-8000 Da range) that are normally lost upon electrophoretic two-dimensional mapping. Such a peptide population, in human sera, may be of particular importance since it may contain protein cleavage products of diagnostic value.     

Comparison between the conventional method of extraction of essential oil of Laurus nobilis L. and a novel method which uses microwaves applied in situ, without resorting to an oven

A novel microwave method has been applied to the hydrothermal extraction of essential oil from plants. An insulated microwave coaxial antenna was introduced inside a 1000 ml glass flask containing dry Laurus nobilis L. leaves and tap water. Microwave power up to 800 W at 2450 MHz was emitted in continuous wave regime (CW) or in pulsed regime (PR) at 8 kW peak power. Stirring with a magnetic bar and a Clevenger refrigerator connected to the flask enabled to complete the extraction in 1 h. The results of the in situ microwave extraction were compared with those obtained by heating the same reactor with a conventional electric mantle by gas chromatography-mass spectrometry (GC-MS) analysis. Differences were observed both in the composition of the essential oil and from the energetic point of view. The essential oil obtained with microwave (MW) methods contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than conventional method. The in situ microwave heating is safe and versatile; it presents time and energy saving advantages, and therefore it can be considered useful also for industrial applications.     

Synthesis of a new series of pyrazolo[1,5‐a]pyrimidines structurally related to zaleplon

The reaction between 3‐(dimethylamino)/3,3‐bis(methylthio)‐1‐(substituted)prop‐2‐en‐1‐ones and 4‐substituted‐5‐amino‐1H‐pyrazoles afforded new pyrazole[1,5‐a]pyrimidines structurally related to Zaleplon. The chemical modifications introduced at the 3‐, 5‐, and 7‐positions of the bicyclic structure revealed new promising candidates for the treatment of sleep disorders.     

Single Drop Dynamics under Shearing Flow in Systems with a Viscoelastic Phase

In this article, we discuss the dynamics of a single drop immersed in an immiscible liquid, under an imposed shear flow. The two situations of a viscoelastic matrix with a Newtonian drop and of a viscoelastic drop in a Newtonian matrix are considered, both systems being characterized by a viscosity ratio equal to one, and by the same elasticity parameter. Experimental data are taken with a rheo-optical computer-assisted shearing device, allowing for drop observation from the vorticity direction of the shear flow. Data favourably compare with predictions of the recently proposed Maffettone-Greco model, where the drop is described as a deforming ellipsoid.     

A model for interfacial electron transfer on colloidal melanin

Though melanins are involved in photochemical reactions (mainly of oxido-reductive type) in vitro and this activity is supposed to have biological implications, no satisfactory model of the reaction kinetics has so far been proposed. The main difficulty arises from the particulate structure of the insoluble melanins and the consequent necessity to describe their reactivity in the framework of heterogeneous chemistry, i.e., at the solid-liquid interface. Our paper presents a simplified model of the monoelectronic reduction reaction of dioxygen, based on well-established experimental facts and some reasonable assumptions: (1) surface adsorption of O₂ on colloidal melanins can be described by a Langmuir isotherm; (2) the kinetics of superoxide formation is photodependent and includes an interfacial electron-transfer process; (3) the photochemical behaviour of the single melanin granule can be described in terms of the electronic properties of amorphous semiconductor particles. Some satisfactory comparisons with experimental data and calculated values of the kinetic constants for the process are presented and discussed.