Trions in a periodic potential

The group-theoretical classification of trion states is presented. It is based on considerations of products of irreducible representations of the 2D translation group. For a given BvK period N degeneracy of obtained states is N^2. Trions consist of two identical particles so the symmetrization of states with respect to particles transposition is considered. Completely antisymmetric states can be constructed by introducing antisymmetric spin functions. Two symmetry adapted bases are considered. The third possibility is postponed for the further investigations.Comment: revtex, 5 p., sub. to Physica

Pairs of Bloch electrons and magnetic translation groups

A product of irreducible representations of magnetic translation group is considered. It leads to irreducible representations which were previously rejected as nonphysical. A very simple example indicates a possible application of these representations. In particular, they are important in descriptions of pairs of electrons in a magnetic field and a periodic potential. The periodicity of some properties with respect to the charge of a particle is briefly discussed.Comment: 4 pages, RevTex. Latex2.09, amsfont

Modeling and Parameter Estimation of an Actuator for Prosthetic Joints

A mathematical model was developed for a linear actuator to be used in a powered leg prosthesis. The model consists of a differential equation relating motor voltage, external force and velocity. All model parameters were known from manufacturer\u27s data, except inertia and friction. A numerical simulation was prepared to estimate these parameters from experimental data. Experiments were conducted and a numerical search was performed to arrive at parameter values that closely fit the data. The mathematical model will be used in subsequent control development work.https://engagedscholarship.csuohio.edu/u_poster_2014/1005/thumbnail.jp

An extension of Fourier analysis for the n-torus in the magnetic field and its application to spectral analysis of the magnetic Laplacian

We solved the Schr{\"o}dinger equation for a particle in a uniform magnetic field in the n-dimensional torus. We obtained a complete set of solutions for a broad class of problems; the torus T^n = R^n / {\Lambda} is defined as a quotient of the Euclidean space R^n by an arbitrary n-dimensional lattice {\Lambda}. The lattice is not necessary either cubic or rectangular. The magnetic field is also arbitrary. However, we restrict ourselves within potential-free problems; the Schr{\"o}dinger operator is assumed to be the Laplace operator defined with the covariant derivative. We defined an algebra that characterizes the symmetry of the Laplacian and named it the magnetic algebra. We proved that the space of functions on which the Laplacian acts is an irreducible representation space of the magnetic algebra. In this sense the magnetic algebra completely characterizes the quantum mechanics in the magnetic torus. We developed a new method for Fourier analysis for the magnetic torus and used it to solve the eigenvalue problem of the Laplacian. All the eigenfunctions are given in explicit forms.Comment: 32 pages, LaTeX, minor corrections are mad

Utjecaj uvjeta grijanja na strukturnu jednolikost i lomno naprezanje aluminijske pjene

In this paper, the possibility to create uniform porous structure for non- symmetric precursor heating was investigated together with changes in collapse stress and their reproducibility. The statistic relative standard deviation (RSD) of pore size was used to determine the structural uniformity. It was shown that proper adjustment of the foaming parameters leads to formation of the uniform foam structure. The compression testing showed that standard deviation of collapse stress was higher for uniform structure than those obtained for non- uniform structure.U ovome radu istražena je mogućnost stvaranja jednolike porozne strukture nesimetričnim zagrijavanjem prekursora, te su isto tako istražene promjene lomnog naprezanja i njihova ponovljivost. Statistička relativna standardna devijacija (RSD) veličine pora koristila se za određivanje strukturne jednolikosti. Pokazano je da pravilan odabir parametara upjenjavanja dovodi do nastajanja jednolike strukture. Tlačna proba je pokazala da je vrijednost standardne devijacije lomnog naprezanja veća za jednoličnu strukturu od onih ostvarenih za nejednoliku strukturu

Slow dynamics of solid proteins : Nuclear Magnetic Resonance relaxometry versus Dielectric Spectroscopy

Acknowledgement This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 668119 (project “IDentIFY”).Peer reviewedPublisher PD

Understanding Selectivity of Mesoporous Silica-Grafted Diglycolamide-Type Ligands in the Solid-Phase Extraction of Rare Earths

Rare earth elements (REEs) and their compounds are essential for rapidly developing modern technologies. These materials are especially critical in the area of green/sustainable energy; however, only very high-purity fractions are appropriate for these applications. Yet, achieving efficient REE separation and purification in an economically and environmentally effective way remains a challenge. Moreover, current extraction technologies often generate large amounts of undesirable wastes. In that perspective, the development of selective, reusable, and extremely efficient sorbents is needed. Among numerous ligands used in the liquid-liquid extraction (LLE) process, the diglycolamide-based (DGA) ligands play a leading role. Although these ligands display notable extraction performance in the liquid phase, their extractive chemistry is not widely studied when such ligands are tethered to a solid support. A detailed understanding of the relationship between chemical structure and function (i.e., extraction selectivity) at the molecular level is still missing although it is a key factor for the development of advanced sorbents with tailored selectivity. Herein, a series of functionalized mesoporous silica (KIT-6) solid phases were investigated as sorbents for the selective extraction of REEs. To better understand the extraction behavior of these sorbents, different spectroscopic techniques (solid-state NMR, X-ray photoelectron spectroscopy, XPS, and Fourier transform infrared spectroscopy, FT-IR) were implemented. The obtained spectroscopic results provide useful insights into the chemical environment and reactivity of the chelating ligand anchored on the KIT-6 support. Furthermore, it can be suggested that depending on the extracted metal and/or structure of the ligand and its attachment to KIT-6, different functional groups (i.e., C= O, N-H, or silanols) act as the main adsorption centers and preferentially capture targeted elements, which in turn may be associated with the different selectivity of the synthesized sorbents. Thus, by determining how metals interact with different supports, we aim to better understand the solid-phase extraction process of hybrid (organo)silica sorbents and design better extraction materials

1H spin-lattice NMR relaxation in the presence of residual dipolar interactions : Dipolar relaxation enhancement

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 668119 (project “IDentIFY”). The role of COST Action CA15209 (European Network on NMR Relaxometry) is also acknowledged.Peer reviewedPublisher PD

Risk factors for work-related eczema and urticaria among vocational students of agriculture

Introduction and objective. Farmers are at high risk of occupational skin diseases which may start already during vocational training. This study was aimed at identification of risk factors for work-related skin diseases among vocational students of agriculture. Materials and method. The study involved 440 students (245 males, 195 females aged 17–21 years) in 11 vocational schools which were at least 100 km from each other. The protocol included a physician-managed questionnaire and medical examination, skin prick tests, patch tests, total IgE and Phadiatop. Logistic regression model was used for the identification of relevant risk factors. Results. Work-related dermatoses were diagnosed in 29 study participants (6.6%, 95%CI: 4.3–8.9%): eczema in 22, urticaria in 14, and co-existence of both in 7 students. Significant risk factors for work-related eczema were: history of respiratory allergy (OR=10.10; p<0.001), history of eczema (itchy rash) provoked by wet work and detergents before entering the school (OR=5.85; p<0.001), as well as history of contact dermatitis to metals, rubber or cosmetics prior to inscription (OR=2.84; p=0.016), and family history of any skin disease (OR=2.99; p=0.013). Significant risk factors for work-related urticaria were: history of allergic rhinitis and asthma prior to inscription (OR=7.29; p=0.006), positive skin prick tests to work place allergens (OR=4.65; p=0.002) and to environmental allergens (OR=3.79; p=0.009), and positive Phadiatop test (OR=3.61; p=0.013). Conclusions. Work-related skin diseases are common among vocational students of agriculture. Atopy, past history of asthma, allergic rhinitis, and eczema (either atopic, allergic or irritant) are relevant risk factors for work-related eczema and urticaria in young farmers, along with family history of any skin disease. Positive skin prick tests seem relevant, especially in the case of urticaria. Asking simple, aimed questions during health checks while enrolling students into agricultural schools would suffice to identify students at risk for work-related eczema and urticaria, giving them the chance for selecting a safer profession, and hopefully avoiding an occupational disease in the future