Photoluminescence and electrical properties in Pr-modified (Ba1-xCax)TiO3 multifunctional ceramics

Mechanoluminescence materials, characterized with non-thermal light emission in response to mechanical stimuli, can have many applications in direct conversion of mechanical energy into light energy. The aim of this study was to develop wet chemistry approaches for the synthesis of the finest ceramic powders of barium calcium titanate for the use in the production of a mechanoluminescent detector. Wet chemistry route allows the control of the particle size of ceramic materials up to several nanometers. For the first time luminescence was recorded in Ba0.9Ca0.1TiO3 ceramics despite reports that light emission in BCT is possibly only over 23% of calcium content. The resulting ceramics showed high relative density, reasonable ferro and dielectric properties, and red light emission can be observed with the naked eye

Synthesis of organic–inorganic hybrid azobenzene materials for the preparation of nanofibers by electrospinning’

The new photochromic hybrid materials containing different mole fractions of highly photoactive 4-[(E)-[4-[ethyl(2-hydroxyethyl)amino]phenyl]azo]-N-(4-methylpyrimidin-2-yl)benzenesulfonamide (SMERe) were prepared by a low temperature sol–gel process. The guest–host systems with triethoxyphenylsilane matrix were obtained. These materials were used to form thin transparent films by a spin-coating technique. Then the ability of thin hybrid films to reversible trans–cis photoisomerization under illumination was investigated using ellipsometry and UV–Vis spectroscopy. The reversible changes of refractive index of the films under illumination were in the range of 0.005–0.056. The maximum absorption of these materials was located at 462–486 nm. Moreover, the organic–inorganic azobenzene materials were used to form nanofibers by electrospinning using various parameters of the process. The microstructure of electrospun fibers depended on sols properties (e.g. concentration and viscosity of the sols) and process conditions (e.g. the applied voltage, temperature or type of the collector) at ambient conditions. The morphology of obtained nanofibers was analyzed by an optical microscopy and scanning electron microscopy. In most instances, the beadless fibers were obtained. The wettability of the surface of electrospun fibers deposited on glass substrates was investigated

Analytical-experimental method for evaluating axial stiffness of the Ilizarow apparatus

Praca prezentuje nietypowe ujęcie problemu wyznaczania sztywności aparatu Ilizarowa zawierającego druty Kirschnera oraz wkręty Schanza. Opracowana metoda obliczeń nie wymaga zastosowania metody elementów skończonych, a jedynie wykonania prostych eksperymentów i obliczeń. Niezbędne w analizie parametry opisujące podatność pierścieni Ilizarowa wyznaczano eksperymentalnie. Istotnym rozwinięciem, w stosunku do wcześniejszych prac jest opracowanie analitycznej metody opisu współpracy pierścieni Ilizarowa z wkrętami Schanza uwzględniającej podatność wszystkich elementów aparatu.This paper presents an uncommon solution to the problem of acquiring the value of stiffness of the Ilizarow apparatus that consists of Kirschner wires and Schanz screws. The proposed method does not require the application of the Finite Element Method, as the only necessary requirement is the execution of a few basic experiments and calculations. The parameters defining the sensibility of the Ilizarow rings are acquired through the experimental means. A significant improvement in comparison to the earlier works in this field is the derivation of the analytical method for describing the cooperation of Ilizarow rings and the Schanz screws, with regard to the sensibility of all the apparatus’ elements

Testis specific serine-threonine kinases : regulation and their role in disease

The phosphorylation of proteins catalyzed by the protein kinases is one of the most important post-translational modifications found in the living cells and is involved in the control, either directly or indirectly, of all processes occurring in the cell. A major challenge in the signal transduction field is to define sequence, structural and mechanistic features responsible for the substrate selectivity, regulation and cellular function of individual protein kinases. We took part in this challenge and studied the family of Testis Specific Serine-threonine Kinases (TSSK) that comprises four members up to date. These kinases are expressed exclusively in testis during spermatogenesis and therefore they are the potential candidates that could be critical for fertilization. The main aim of this thesis was to give more insight into the biochemical properties and possible function(s) of TSSK3. Chapter 2 describes the analysis of biochemical properties, substrate specificity and in vitro activation of one of TSSK family members, TSSK3. In vitro TSSK3 exhibited the ability to autophosphorylate and to phosphorylate test substrates providing the evidence that TSSK3 is a genuine kinase. Sequence comparison indicated the existence within the TSSK3 catalytic domain of a so-called 'T-loop' a structure present in the AGC-family of protein kinases. To test if this T-loop is engaged in TSSK3 regulation, we mutated the critical threonine within the T-loop to alanine (T168A) and this resulted in an inactive TSSK3 kinase. Furthermore in vitro Thr-168 is phosphorylated by the T-loop kinase phosphoinositide-dependent protein kinase-1 (PDK1) and phosphorylation by PDK1 increased in vitro TSSK3 kinase activity, suggesting that TSSK3 can be regulated in the same way as AGC-kinase family members. Furthermore, analysis of a range of peptide sequences defines the peptide sequence, RRSSSY, as an efficient and specific substrate for TSSK3. In Chapter 3, we searched for TSSK3 potential regulatory interacting proteins by a yeast two-hybrid approach. We identified, a novel, widely expressed protein, RUSC2 and we showed that it binds to but is not a substrate for TSSK3. We also observed it to be phosphorylated by Jun NH2-terminal kinase (JNK). Next, we demonstrated that RUSC2 transiently interacts with JNK kinases after oxidative stress treatment and that TSSK3 appears in this stress-induced complex as well. Furthermore we showed that this interaction is abolished by inhibitory mutant of MKK4. In this chapter we pointed out the possible connection between RUSC2, TSSK3 and oxidative stress induced JNK signaling pathway. Chapter 4 describes our search for mutations in two other genes of the TSSK family, TSSK1 and 2, in patients with infertility. We found, single nucleotide polymorphism (SNP) in the TSSK2 gene, which changed threonine residue, located in the C-terminal regulatory domain of TSSK2, to methionine (T280M) that may be correlated with spermatogenic failure. Thus, TSSK2 might be a candidate gene for molecular marker for genetic diagnosis of male infertility. In Chapter 5, a model for RUSC2 assembly with TSSK3, JNK and H-Ras is proposed and the possible directions of future studies on TSSK family and their role in signal transduction are discusse

Structural And Electrical Properties Of The Selected Rare-Earth Oxychlorides

The preparation and sintering conditions of the selected rare-earth oxychlorides REOCl (Re=La, Nd, Sm, Gd) were determined. The purity of materials phase compositions was confirmed by X-ray diffraction method. Further analysis of the data enabled lattice parameters and average grain size determination. The electrical properties of the single phase REOCl materials were investigated by Electrochemical Impedance Spectroscopy in wide temperature range in atmospheric air. The spectra were analyzed by the equivalent circuit fitting. Basing on the values of equivalent circuits parameters the specific conductivities were calculated and presented in the Arrhenius coordinates. Energies of activation were calculated. The determined structural and electrical properties of four different rare-earth oxychlorides were directly compared

Strukturalne i elektryczne własności wybranych tlenochlorków metali ziem rzadkich

The preparation and sintering conditions of the selected rare-earth oxychlorides REOCl (Re=La, Nd, Sm, Gd) were determined. The purity of materials phase compositions was confirmed by X-ray diffraction method. Further analysis of the data enabled lattice parameters and average grain size determination. The electrical properties of the single phase REOCl materials were investigated by Electrochemical Impedance Spectroscopy in wide temperature range in atmospheric air. The spectra were analyzed by the equivalent circuit fitting. Basing on the values of equivalent circuits parameters the specific conductivities were calculated and presented in the Arrhenius coordinates. Energies of activation were calculated. The determined structural and electrical properties of four different rare-earth oxychlorides were directly compared.Ustalono warunki syntezy i spiekania wybranych tlenochlorków metali ziem rzadkich, a mianowicie LaOCl, NdOCl, SmOCl oraz GdOCl. Czystość składów fazowych materiałów potwierdzono metodą dyfrakcji promieniowania rentgenowskiego. Analiza uzyskanych danych pozwoliła na wyznaczenie wartości stałych sieciowych oraz średniej wielkości ziaren. Własności elektryczne materiałów wyznaczono metodą elektrochemicznej spektroskopii impedancyjnej w szerokim zakresie temperatur w powietrzu atmosferycznym. Do każdego z widm dopasowano układ zastępczy. Na tej podstawie wyznaczono wartości przewodnictw właściwych i sporządzono wykresy Arrheniusa oraz wyznaczono wartości energii aktywacji. Przeprowadzone badania pozwoliły na bezpośrednie porównanie własności strukturalnych i elektrycznych tlenochlorków czterech różnych metali ziem rzadkich