Searching for Major Urinary Proteins (MUPs) as Chemosignals in Urine of Subterranean Rodents

Chemosensory information mediates behavior in many rodent genera. Major Urinary Proteins (MUPs) facilitate chemical communication in some species of mice. We sought to demonstrate the importance of MUPs in chemosignaling across a range of rodent genera that live in different habitats and social structures. We analyzed urine from three subterranean rodent genera from different continents, and with diverse social systems: eusocial Zambian mole-rats (Fukomys), solitary Israeli blind mole rats (Spalax), and social Chilean coruros (Spalacopus). 2D gel electrophoresis revealed low levels of protein, with sequences similar to aphrodisin, in Fukomys mole-rat urine, but no MUPs in urine of any of the studied species. Previous research demonstrated that subjects from the tested genera responded differentially to odors indicating transmission of individuality, family/colony or population, species, and reproductive state in secretions and excretions of conspecifics. This extends, to subterranean rodents, the evidence that rodent species can successfully transmit and receive chemosignals without the necessity of MUPs.     

Deposition of Al nanoparticles and their nanocomposites using a gas aggregation cluster source

The study describes the preparation and properties of Al/Al _x O _y nanoparticles and their nanocomposites with hydrocarbon plasma polymer. The nanoparticles were deposited using a simple gas aggregation cluster source based on a planar magnetron. The influence of deposition parameters on size distribution was studied. It was found that Al nanoparticles may be deposited with mean diameter ranging from 30 to 60 nm by varying magnetron current from 0.4 to 0.2 A. Attention was also paid to the investigation of the charge of the nanoparticles. It is shown that a large portion of Al _x O _y nanoparticles leave the gas aggregation source as negatively charged. The nanoparticles were also embedded into the plasma polymer matrix by their simultaneous co-deposition with plasma-polymerized n-hexane. Morphology and chemical composition of such fabricated nanocomposites were determined. It was shown that Al _x O _y nanoparticles embedded into the polymeric matrix exhibit localized surface plasmon resonances in the deep ultraviolet region of the electromagnetic spectrum and the position of the plasmon peak is strongly correlated with nanoparticle size.     

Layered ceramic composites via control of electrophoretic deposition kinetics

The article summarises optimisation of electrophoretic deposition of alumina and zirconia from concentrated isopropanolic suspensions stabilised by monochloracetic acid. Method for in situ monitoring of deposited mass was developed and experimentally checked. Prediction of electrophoretic deposition kinetics was based on the voltage drop measurement and electrophoretic mobility estimation from experimental kinetics data. It was shown that voltage change during electrophoretic deposition did not affect relative density of the deposited layers in the laminates prepared. For this purpose a method of the relative density measurement using the microscopic measurement of relative shrinkage of individual layers was developed. Accuracy of the method was confirmed by comparison with shrinkage measurement using high temperature dilatometry. Adopting obtained results the alumina/zirconia laminate with precise control of layers thicknesses and final densities was prepared.     

Flow method for study of gas transport in polymers. Application to the study of oxygen,nitrogen, and carbon dioxide permeation through cellulose acetate membranes

Transient permeation of oxygen, nitrogen, and carbon dioxide through certain cellulose acetate (CA) dense membrances made from solutions in dioxane and dioxane-added ethanol were studied by the flow method. In order to explain the overshoots for transient permeation rates in the latter case, a new model is proposed. It postulates a time-dependence solubility coefficient, in the form of a series of exponential terms, which is combined in Fick's second law and solved. The model fits well the obtained permeation kinetics, leading to values of the diffusion, and permeation coefficients, and the structure change-related time. The overshoots are explained by the formation of unstable structure from dioxane-ethanol solvent mixtures, a memory effect of aggregated chains, which undergoes consolidation upon gas penetration. The stable state which results from the consolidation process is the same as that of membrances obtained from pure dioxane solutions. © 1994 John Wiley & Sons, Inc.     

Magnetically induced behaviour of ferritin corpuscles in avian ears: can cuticulosomes function as magnetosomes?

Magnetoreception is an enigmatic, poorly understood sensory ability, described mainly on the basis of behavioural studies in animals of diverse taxa. Recently, corpuscles containing superparamagnetic iron-storage protein ferritin were found in the inner ear hair cells of birds, a predominantly single ferritin corpuscle per cell. It was suggested that these corpuscles might represent magnetosomes and function as magnetosensors. Here we determine ferritin low-field paramagnetic susceptibility to estimate its magnetically induced intracellular behaviour. Physical simulations show that ferritin corpuscles cannot be deformed or rotate in weak geomagnetic fields, and thus cannot provide magnetoreception via deformation of the cuticular plate. Furthermore, we reached an alternative hypothesis that ferritin corpuscle in avian ears may function as an intracellular electromagnetic oscillator. Such an oscillator would generate additional cellular electric potential related to normal cell conditions. Though the phenomenon seems to be weak, this effect deserves further analyses.     

Rhenium Oxide Supported on Mesoporous Organised Alumina as a Catalyst for Metathesis of 1-Alkenes

Sulphate-promoted alkane combustion has been investigated over a series of Pt/Al₂O₃ catalysts using pre-sulphated alumina supports. Catalyst sulphation greatly enhanced ethane combustion over Pt/Al₂O₃, and also improved methane and propane light-off performance. Catalyst activity increased with Pt loading, however the magnitude of sulphate promotion was independent of Pt loading under oxidising conditions, but scaled with alkane chain length. Propane combustion activity was directly proportional to the surface coverage of aluminium sulphate sites; support-mediated alkane activation is the dominant process in sulphate promotion.     

On the determination of the stress-free temperature for alumina–zirconia multilayer structures

Internal residual stresses can enhance the fracture resistance and mechanical reliability of layered ceramics. The magnitude of the stresses depends on the elastic and thermal properties of the layers and the typically assumed reference (stress-free) temperature, below which internal stresses develop. A novel combined experimental and numerical simulation approach has been developed to determine the reference temperature and experimentally proved in alumina–zirconia ceramic laminates. Dilatometric data of monolithic phases are input for the numerical simulation and experimental data on the laminate properties are used for the stress-free temperature determination. In contrast to typical assumptions, reference temperature very near the sintering temperature (i.e. approx. T_ref≈1470 °C) was found, which should be considered for the estimation of internal (residual) stresses in alumina/zirconia-based layered ceramics.     

SBA-15 Immobilized Ruthenium Carbenes as Catalysts for Ring Closing Metathesis and Ring Opening Metathesis Polymerization

New hybrid catalysts for olefin metathesis were prepared by immobilization of Hoveyda–Grubbs type Ru alkylidenes on a siliceous SBA-15 support via exchange of chloro ligands for substituted carboxylates. Catalysts proved a high activity in ring closing metathesis of 1,7-octadiene and diethyl diallylmalonate, reusability and low Ru leaching. In Ring Opening Metathesis Polymerization of norbornene and cyclooctene, SBA-15 supported catalyst gave higher yields of high-molecular-weight polymers than corresponding catalyst with conventional silica support.