Transient kinetics of toluene partial oxidation over V/Ti oxide catalysts

Transient kinetics in the toluene oxidation over V/Ti oxide catalysts prepared by grafting and impregnation have been compared. V⁴⁺ cations are supposed to be the sites for the formation of electrophilic oxygen species participating in deep oxidation. Another oxygen species (probably nucleophilic) present on the oxidised catalyst surface are responsible for benzaldehyde formation. Selectivity of 80–100% can be obtained during the initial period of the reaction on the grafted catalysts in the presence of gaseous oxygen and during the interaction of toluene (without O₂ in the mixture) with partially reduced catalysts.     

Observations of the electrical behaviour of catalytically grown scrolled graphene

Carbon nanoscrolls, made of rolled up graphene, are expected to show unique electronic properties different from those of nested multi-wall tubes. Here we report in situ TEM observations and electrical measurements of the transport and breakdown behaviour of catalytically grown, multi-turn monochiral graphene scrolls, 30–65 nm in outer diameter. Generally, the low-bias IV region proved strictly linear Ohmic behaviour, non-linear increase in conductance occurred beyond an applied voltage of ∼0.4 V. Excellent maximum conductance values up to G ∼ 63 G₀ and sustainable current-carrying capacities up to J = 8.5 × 10⁸ A/cm² were found in the most successful samples right before electric breakdown. Inferior values are ascribed to defect-rich or semiconducting scrolls. This study emphasizes the promising nature of carbon nanoscrolls for a number of electronic device applications.     

Studies on Preparation and Hydrogen Storage Properties of Dual-Metal Ferrocenyl Coordination Polymer Microspheres

A series of dual-metal ferrocenyl coordination polymer microspheres (M₁M₂-CPMs, M₁M₂ = CoMn, CoCu, MnCu) were synthesized by the reaction of 1,1′-ferrocene dicarboxylic acid with mixed metal salts via solvothermal method. From SEM and TEM images, it was found that all the as-synthesized coordination polymers showed microspheres structures. The products were also characterized by X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The M₁M₂-CPMs showed good thermostability and remained stable up to 250 °C. These M₁M₂-CPMs exhibited hydrogen uptake capacity. More interestingly, through the comparison among three microspheres we found that the M₁M₂-CPMs with hollow structures showed better hydrogen uptake.     

SURFACE IMPREGNATED SULFONATE ION EXCHANGERS: PREPARATION,PROPERTIES AND APPLICATION

ABSTRACT

This paper reviews the results obtained by studying Surface Impregnated Sulfonate Ion Exchangers (SISIE) obtained by modification of macroporous or gel polysterene-divinylbenzene polymers with toluene solutions of dinonytnaphihalene sulfonic acids. Capacities of SISIE of the first type are directly proportional to the concentration of the modifying solution and to the specific surface area of the matrix. Capacities of gel SISIE are much less than those of macroporous samples and depend on the crosslinking of the matrix. Stabilization of SISIE capacity and improvement of their kinetic properties can be achieved using “wet drying ” technique. Successive impregnation of the same SISIE sample may be used to increase the capacity of the resin. The ion-exchange properties of SISIE are mainly determined by their micellar structure which also defines the areas of possible applications of these ion-exchange materials such as, e.g. ion chromatography and some others Several models have been successfully applied to describe the features of ion exchange processes on SISIE. Application of SISIE as convenient model systems to study aminecarboxylate interaction of amino acid molecules is illustrated by suspension effects measured in SISIE-zwitterlyte and SISIE-HCI suspensions and by the results obtained by the laser-acoustic study of these systems.     

Ribosomal Protein S5e is Implicated in Translation Initiation through its Interaction with the N‐Terminal Domain of Initiation Factor eIF2α

A key step of translation initiation in eukaryotes is formation of the 48S preinitiation complex (PIC) containing the 40S ribosome, a set of eukaryotic initiation factors (eIFs), mRNA, and initiator Met‐tRNA interacting with mRNA start codon; however, the PIC structure remains substantially unknown. Here, we apply formaldehyde‐induced protein–protein crosslinks to identify contacts between ribosomal protein S5e (rpS5e, “e” stands for “eukaryotic”) and eIFs within the mammalian PIC, assembled on either model canonical or IRES‐containing mRNA. Using immunoblotting and mass spectrometry, we show that with both types of mRNA, rpS5e crosslinks to eIF2α. Comparative analysis of peptides resulting from trypsinolysis of the crosslinked proteins before and after crosslink reversal reveals crosslinked peptides in the N‐terminal parts of rpS5e and eIF2α. Application of these data to a model PIC structure obtained with the use of available structures indicates that eIF2α undergoes major conformation rearrangements to enable contacts of the factor with rpS5e. These contacts are suggested to maintain the correct positioning of eIF2α relative to other PIC components; this could be essential for start‐codon selection by the PIC.     

Stabilising Cobalt Sulphide Nanocapsules with Nitrogen-Doped Carbon for High-Performance Sodium-Ion Storage

Conversion-type anode materials with a high charge storage capability generally su er from large volume expansion, poor electron conductivity, and sluggish metal ion transport kinetics. The electrode material described in this paper, namely cobalt sulphide nanoparticles encapsulated in carbon cages(Co9S8@NC), can circumvent these problems. This electrode material exhibited a reversible sodium-ion storage capacity of 705 mAh g^-1 at 100 mA g^-1 with an extraordinary rate capability and good cycling stability. Mechanistic study using the in situ transmission electron microscope technique revealed that the volumetric expansion of the Co9S8 nanoparticles is bu ered by the carbon cages, enabling a stable electrode–electrolyte interface. In addition, the carbon shell with high-content doped nitrogen significantly enhances the electron conductivity of the Co9S8@NC electrode material and provides doping-induced active sites to accommodate sodium ions. By integrating the Co9S8@NC as negative electrode with a cellulose-derived porous hard carbon/graphene oxide composite as positive electrode and 1 M NaPF6 in diglyme as the electrolyte, the sodium-ion capacitor full cell can achieve energy densities of 101.4 and 45.8 Wh kg^-1 at power densities of 200 and 10,000 W kg^-1, respectively.     

Plasmalogens,fatty acids and alkyl glyceryl ethers of marine and freshwater clams and mussels

Shelled molluscs constitute an excellent source of protein, sugars and lipids, and the demand for various mollusks species is increasing. We analysed lipid composition of different bivalves, quite important in the diet of East Mediterranean inhabitants. Plasmamlogens, glyceryl ethers, and diacyl phospholipid forms as well as their fatty aldehydes, fatty alcohols, and fatty acid derivatives were examined. PE of clams and mussels, containing aldehydes C16 (variations from 4% to 31%), C18 (29–46%), C9–18:1(6–32%), C11–20:1 (3–19%), and several minor aldehydes, were detected. The major saturated 1-O-alkyl glycerol ethers C16 and C18. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in both PE and PS plasmalogens were dominated acids. The sum of these acids in PE varied from 33% to 43%, and in PS, from 45% to 66%. EPA levels in PE (30–37%) and PS (39–57%) of marine species were higher than those in freshwater species (PE, 13–16%; PS, 23–29%), and levels of DHA were higher in freshwater than in marine mollusks. A series of saturated fatty aldehydes C12–C24, with major C18:0 in all studied species (over 40%) and C16:0 (10–25%), as well as of unsaturated C16:1 (1–7%) and 18:1 (18–36%) species were isolated from neutral plasmalogens. Predominant fatty acids in neutral plasmalogens were found to be 16:0 (12–17%), 20:5n−3 (9–27%), and 22:6n−6 (9–18%). Distribution of plasmalogens, alkyl glyceryl ethers, and their fatty aldehydes and fatty alcohols in mollusks and other invertebrates is discussed.     

Low-Voltage Magnetoelectric Coupling in Fe0.5Rh0.5/0.68PbMg1/3Nb2/3O3-0.32PbTiO3 Thin-Film Heterostructures

The rapid development of computing applications demands novel low-energy consumption devices for information processing. Among various candidates, magnetoelectric heterostructures hold promise for meeting the required voltage and power goals. Here, a route to low-voltage control of magnetism in 30 nm Fe_0.5Rh_0.5/100 nm 0.68PbMg_1/3Nb_2/3O₃-0.32PbTiO₃ (PMN-PT) heterostructures is demonstrated wherein the magnetoelectric coupling is achieved via strain-induced changes in the Fe_0.5Rh_0.5 mediated by voltages applied to the PMN-PT. We describe approaches to achieve high-quality, epitaxial growth of Fe_0.5Rh_0.5 on the PMN-PT films and, a methodology to probe and quantify magnetoelectric coupling in small thin-film devices via studies of the anomalous Hall effect. By comparing the spin-flop field change induced by temperature and external voltage, the magnetoelectric coupling coefficient is estimated to reach ≈7 × 10⁻⁸ s m⁻¹ at 325 K while applying a −0.75 V bias.     

Rounding Out the Understanding of ACD Toxicity with the Discovery of Cyclic Forms of Actin Oligomers

Actin is an essential element of both innate and adaptive immune systems and can aid in motility and translocation of bacterial pathogens, making it an attractive target for bacterial toxins. Pathogenic Vibrio and Aeromonas genera deliver actin cross-linking domain (ACD) toxin into the cytoplasm of the host cell to poison actin regulation and promptly induce cell rounding. At early stages of toxicity, ACD covalently cross-links actin monomers into oligomers (AOs) that bind through multivalent interactions and potently inhibit several families of actin assembly proteins. At advanced toxicity stages, we found that the terminal protomers of linear AOs can get linked together by ACD to produce cyclic AOs. When tested against formins and Ena/VASP, linear and cyclic AOs exhibit similar inhibitory potential, which for the cyclic AOs is reduced in the presence of profilin. In coarse-grained molecular dynamics simulations, profilin and WH2-motif binding sites on actin subunits remain exposed in modeled AOs of both geometries. We speculate, therefore, that the reduced toxicity of cyclic AOs is due to their reduced configurational entropy. A characteristic feature of cyclic AOs is that, in contrast to the linear forms, they cannot be straightened to form filaments (e.g., through stabilization by cofilin), which makes them less susceptible to neutralization by the host cell.