Measuring the deformation of a ferrogel sphere in a homogeneous magnetic field

A sphere of a ferrogel is exposed to a homogeneous magnetic field. In accordance to theoretical predictions, it gets elongated along the field lines. The time-dependence of the elastic shear modulus causes the elongation to increase with time analogously to mechanic creep experiments, and the rapid excitation causes the sphere to vibrate. Both phenomena can be well described by a damped harmonic oscillator model. By comparing the elongation along the field with the contraction perpendicular to it, we can calculate Poisson's ratio of the gel. The magnitude of the elongation is compared with the theoretical predictions for elastic spheres in homogeneous fields.Comment: 5 pages, 8 figure

Problems and Exercises in Medical Physics with Examples and Solutions: teaching methodical practical manual. For English-speaking students of medical, biomedical and pharmaceutical fields of study

"Problems and Exercises in Medical Physics with Examples and Solutions" is intended for students of foreign groups of medical specialties of the university. Example problems and exercises with brief theoretical background and complete solution are presented for five domains of physics: Mechanics, Molecular Physics, Electricity and Magnetism, Sound and Waves, and Optics. Tasks for independent study are given at the end of the brochure.3

Practical work. Medical physics. Part 4. Electricity and magnetism. Part 5. Optics

Collection of descriptions of laboratory work "Practical work. Medical physics. Part 4. Electricity and magnetism. Part 5. Optics" is intended for students of foreign groups of medical specialties of the university, provided by a brief overview, installation manuals, step-by-step instructions and a list of questions for self-examination.8

Ethanol Clusters in Gasoline-Ethanol Blends

Formation of ethanol clusters in gasoline-ethanol fuel blends was studied by pulsed-field-gradient NMR measurement of diffusion of ethanol molecules. The results, consistent with a simple model of clusterization, show that ethanol molecules form hydrogen-bonded clusters with concentration- and temperature-dependent average size. Association/dissociation kinetics is fast, and the measured diffusion coefficients are average values. Water molecules are attached to ethanol clusters and have the same coefficient of diffusion

Practical work. Medical physics. Part 1. Mechanics. Part 2. Molecular physics

Collection of descriptions of laboratory work "Practical work. Medical physics. Part 1. Mechanics. Part 2. Molecular physics" is intended for students of foreign groups of medical specialties of the University. For each work, a brief overview, installation manuals, step-by-step instructions, and a list of questions for self-study are provided.9

Predicting the Potentiometric Sensitivity of Membrane Sensors Based on Modified Diphenylphosphoryl Acetamide Ionophores with QSPR Modeling

While potentiometric, plasticized membrane sensors are known as convenient, portable and inexpensive analytical instruments, their development is time- and resource-consuming, with a poorly predictable outcome. In this study, we investigated the applicability of the QSPR (quantitative structure–property relationship) method for predicting the potentiometric sensitivity of plasticized polymeric membrane sensors, using the ionophore chemical structure as model input. The QSPR model was based on the literature data on sensitivity, from previously studied, structurally similar ionophores, and it has shown reasonably good metrics in relating ionophore structures to their sensitivities towards Cu2+, Cd2+ and Pb2+. The model predictions for four newly synthesized diphenylphosphoryl acetamide ionophores were compared with real potentiometric experimental data for these ionophores, and satisfactory agreement was observed, implying the validity of the proposed approach

Block copolymers as dispersants for nanomaterial added to fuel

Development and optimization of technologies using nanocomposite materials is one of important areas in modern industrial engineering. In transport industry and in fuel power engineering the use of nanoparticles can optimize fuel consumption, reduce pollutants, and increase aggregate productivity. A special role belongs to carbon nanomaterials, primarily to multi- and single-walled carbon nanotubes, since, beside the improvement of fuel characteristics, they can be completely utilized during combustion. Application of nanoparticles requires the preparing of stable suspensions suitable for various technological processes. In this work by the help of NMR spectroscopy the dispersing of nanomaterial by block copolymers was considered: by poloxamers (P184 and P407) in aqueous medium and by poloxamine (Diproxamine-157) and its mixture with liquid poloxamer P184 in oil medium. Good dispersibility of nanomaterial and stability of aqueous dispersions obtained with the help of poloxamers have been shown. Also, it has been established that pure liquid reverse-sequential poloxamines can be used to create oil-soluble dispersions of nanomaterial. Possible mechanisms to prevent reagglomeration by the help of poloxamines have been considered

Paraffinic oil residues after heating as a basis for fuel

The possibility of reuse of heavy residues (oily sludge) of low-sulfur, highly paraffinic Mangyshlak oils as a basis for fuel with improved environmental characteristics for engines to marine, river and railway transport, gas turbine and boiler plants, steam boilers and industrial furnaces was shown. A variant of the joint application of the methods of nuclear magnetic resonance, laser confocal microscopy and rheology for study of micro- and mesoscopic structure and some physicochemical properties of crude oil products has been developed. It has been shown that preliminary heating to 90 ° C leads to disruption of the structure and hydrogen bonds between oil associates and complexes, increasing sample homogeneity due to precipitation of solid impurities, partial removal of water content, air bubbles and dissolved gases. The addition of medium distillate diesel fractions to preliminary heated oil residues will make it possible to obtain a higher quality version of the fuel with a reduced resinous and asphaltene substances, lower pour point, good energy content and low sulfur content. Thus, valuable energy-containing raw materials can be reused. It should also be noted that the reuse of accumulated oil waste will reduce the harmful effects of landfills, will preserve the natural landscape, and will cut the cost of extracting natural resources

Speciation of uranium(VI) extracted from acidic nitrate media by TODGA into molecular and ionic solvents

International audienceThe speciation of uranium(VI) extracted by a molecular extractant N,N,N′,N′-tetra(n-octyl)diglycolamide (TODGA) and a hydrophobic ionic liquid (IL), namely 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4mim][Tf2N], mixture from acidic nitrate media in 1,2-dichloroethane (DCE), and, for comparison, with only TODGA dissolved in DCE or IL has been studied by UV–vis and EXAFS spectroscopy. Our results confirm that the extraction in the conventional system occurs via a common solvation mechanism, at high acidity the extracted complex was identified as [UO2(NO3)2(TODGA)]. The addition of hydrophobic bistriflimide anions (Tf2N−) in the aqueous phase or IL in the organic phase results in a formation of another uranyl complex, in which two tridentate TODGA ligands directly coordinate metal cation and two NO3 – and/or Tf2N− anions are expulsed in the outer sphere and act as charge balancing ions. When pure IL is used as diluent for TODGA ligand, the extracted uranyl complex has the same composition and stoichiometry as in the previous case, [UO2(TODGA)2] 2+