Jan Długosz University

About: Jan Długosz University is a education organization based out in Częstochowa, Poland. It is known for research contribution in the topics: Crystal structure & Luminescence. The organization has 749 authors who have published 2311 publications receiving 19395 citations. The organization is also known as: Higher Teacher Education School.

Structural study of polymer hydrogel contact lenses by means of positron annihilation lifetime spectroscopy and UV-vis-NIR methods.

Abstract: A study has been conducted in order to determine presence of free volume gaps in the structure of structure of polymer hydrogel contact lenses made in phosphoryl choline technology and of the degree of defect of its structure. The study was made by means of positron annihilation lifetime spectroscopy. As a result of the conducted measurements, curves were obtained, which described numbers of counts of the acts of annihilation in the time function. The conducted studies revealed existence of three components τ1, τ2 and τ3. The τ3 component is attributed to the pick-off annihilation of o-Ps orthopositronium trapping by free volume gaps and provides information about geometrical parameters of the volumes. At the same time, the UV–vis–NIR spectrometry examination was conducted on the same samples in the spectral range 200–1,000 nm.

Influence of Bi on topological self-organization in arsenic and germanium selenide networks

Abstract: The influence of Bi on the network structure of Ge20Se80−yBiy and As40−ySe60Biy glasses is investigated by high-resolution X-ray photoelectron spectroscopy (XPS). The results show that Bi enters the glass network of both Ge–Se and As–Se glass systems in the form of BiSe3/2 pyramids, with a significant increase in the concentration of homopolar Ge–Ge and As–As bonds, respectively, compared to Bi-free samples. In these compositions, topological self-organization is found to play a minor role in comparison to phase separation tendencies at the nanoscale caused by Bi addition. It is suggested that BiSe3/2 rich regions occur as partially ordered nano-thin sheets, which may account for the percolative-type response of electrical conductivity observed in similar Bi containing systems.

Crystallization of amorphous Fe78Si9B13 alloy

Abstract: The crystallization process of Fe78Si9B13 metallic glass was investigated by DSC, X-ray diffraction, electrical resistivity, Hall effect and TEM methods. The investigations proved two-stages crystallization. By means of non-isothermal DSC experiments the activation energy and the Avrami exponent were determined for both stages. The created phases: α-Fe(Si) and (Fe,Si)2B were identified on the basis of X-ray and TEM investigations. However, TEM observations showed also a little amount of the FeB49 phase as well as some rest of the amorphous phase. The electrical and Hall resistivities decrease abruptly after the creation of the phases out of the amorphous matrix.

Time-fractional heat conduction in an infinite medium with a spherical hole under robin boundary condition

Abstract: The time-fractional heat conduction equation with the Caputo derivative of the order 0 < α ≤ 2 is considered in an infinite medium with a spherical hole in the central symmetric case under two types of Robin boundary condition: the mathematical one with the prescribed linear combination of the values of temperature and the values of its normal derivative at the boundary and the physical condition with the prescribed linear combination of the values of temperature and the values of the heat flux at the boundary. The integral transforms techniques are used. Several particular cases of the obtained solutions are analyzed. The numerical results are illustrated graphically.