The Mossbauer spectra of prasiolite and amethyst crystals from Poland

Mössbauer spectroscopy of green (prasiolite) and violet (amethyst) quartz crystals from the Sudety Mountains (Poland) has shown that neither Fe2+ nor Fe4+ ions are present in them. Only Fe3+ ions have been identified and only in interstitial positions in channels parallel or perpendicular to the c-axis. The valence of Fe3+ ions did not change as a result of irradiation or annealing. Instead, we believe that the Fe3+ ions move within channels or between them

Impact of marathon performance on muscles stiffness in runners over 50 years old

IntroductionThe research examines the relationship between marathon performance and muscle stiffness changes from pre to marathon in recreational runners aged 50+ years.MethodsThirty-one male long-distance runners aged 50–73 years participated in the experiment. The muscle stiffness of quadriceps and calves was measured in two independent sessions: the day before the marathon and 30 min after the completed marathon run using a Myoton device.Results and DiscussionThe 42.195-km run was completed in 4.30,05 h ± 35.12 min, which indicates an intensity of 79.3% ± 7.1% of HRmax. The long-term, low-intensity running exercise (marathon) in older recreational runners and the low level of HRmax and VO2max showed no statistically significant changes in muscle stiffness (quadriceps and calves). There was reduced muscle stiffness (p = 0.016), but only in the triceps of the calf in the dominant (left) leg. Moreover, to optimally evaluate the marathon and adequately prepare for the performance training program, we need to consider the direct and indirect analyses of the running economy, running technique, and HRmax and VO2max variables. These variables significantly affect marathon exercise

Interactions in solutions and gels of stimuli-responsive polymer systems investigated by NMR spectroscopy

Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),..

INTERAKCE V ROZTOCÍCH A GELECH NA PODNĚTY REAGUJÍCICH POLYMERNÍCH SYSTÉMŮ STUDOVANÝCH NMR SPEKTROSKOPIÍ

Na podněty reagující (na podněty citlivé nebo inteligentní) polymery jsou polymerní materiály, které na malé vnější podněty očividně mění své fyzikální nebo chemické vlastnosti. Inteligentní polymery lze klasifikovat podle podnětů, na které reagují, jako jsou změny teploty, mechanické namáhání, ozáření světlem, aplikace ultrazvuku, aplikace vnějšího magnetického či elektrického pole, změny pH, iontové síly, přidání chemických činidel a přítomnost biomolekul či bioaktivních molekul. Na podněty reagující systémy syntetických polymerů přitahují značnou pozornost díky širokému spektru aplikací, jako jsou systémy pro řízené dodávání a uvolňování léčiv, diagnostiku, tkáňové inženýrství a "inteligentní" optické systémy, stejně jako biosenzory, mikroelektromechanické systémy, nátěry a textilie. V této disertaci byly studovány polymerní systémy reagující na teplotu, pH a reaktivní kyslík (ROS). V případě termoresponsivních polymerů, kdy jsou v dobrém rozpouštědle polymerní řetězce molekulárně rozpuštěny, se změnami teploty (zvýšení nebo pokles) dochází k teplotou- indukované fázové separaci a tvorbě globulárních nanočástic. Polymery reagující na pH mění své vlastnosti, jako jsou rozpustnost, objem (gely), konformace řetězce, jakož i vazby, které se mohou při změnách pH štěpit. ROS-responzivita může vést ke...Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),...Katedra fyzikální a makromol. chemieDepartment of Physical and Macromolecular ChemistryPřírodovědecká fakultaFaculty of Scienc

Effect of PAMAM Dendrimers on Interactions and Transport of LiTFSI and NaTFSI in Propylene Carbonate-Based Electrolytes

Poly(amidoamine) (PAMAM)-based electrolytes are prepared by dissolving the PAMAM half-generations G1.5 or G2.5 in propylene carbonate (PC), either with lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) or sodium bis(trifluoromethylsulfonyl)imide (NaTFSI) salts. The solutions, designed for ion battery applications, are studied in terms of ions transport properties. Raman Spectroscopy reveals information about the interactions between cations and PAMAM dendrimers as well as full dissociation of the salts in all solutions. Pulsed-field gradient Nuclear Magnetic Resonance (PFG NMR), measured as a function of both temperature and PAMAM concentration, are obtained for the cation, anion, solvent, and dendrimer molecules using lithium (7Li), sodium (23Na), fluorine (19F), and hydrogen (1H) NMR, respectively. It was found that lithium diffusion is slow compared to the larger TFSI anion and decreases with PAMAM concentration due to interactions between cation and dendrimer. Comparison of conductivities calculated from diffusion coefficients using the Nernst–Einstein equation, with conductivity measurements obtained from Impedance Spectroscopy (IS), shows slightly higher IS conductivities, caused among others by PAMAM conductivity

Interactions in solutions and gels of stimuli-responsive polymer systems investigated by NMR spectroscopy

Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),..

Temperature Behavior of Aqueous Solutions of Poly(2-Oxazoline) Homopolymer and Block Copolymers Investigated by NMR Spectroscopy and Dynamic Light Scattering

1H NMR methods in combination with dynamic light scattering were applied to study temperature behavior of poly(2-isopropyl-2-oxazoline) (PIPOx) homopolymer as well as PIPOx-b-poly(2-methyl-2-oxazoline) (PMeOx) and poly(2-ethyl-2-oxazoline) (PEtOx)-b-PMeOx diblock copolymers in aqueous solutions. 1H NMR spectra showed a different way of phase transition for the main and side chains in PIPOx-based solutions. Additionally, the phase transition is irreversible for PIPOx homopolymer and partially reversible for PIPOx-b-PMeOx copolymer. As revealed by NMR, the phase transition in PEtOx-based copolymers solutions exists despite the absence of solution turbidity. It is very broad, virtually independent of the copolymer composition and reversible with some hysteresis. Two types of water molecules were detected in solutions of the diblock copolymers above the phase transition—“free” with long and “bound” with short spin–spin relaxation times T2. NOESY spectra revealed information about conformational changes observed already in the pre-transition region of PIPOx-b-PMeOx copolymer solution

N -(2-Hydroxypropyl)methacrylamide-Based Linear, Diblock, and Starlike Polymer Drug Carriers: Advanced Process for Their Simple Production

International audienc

Smart Poly(lactide)-<i>b</i>-poly(triethylene glycol methyl ether methacrylate) (PLA-<i>b</i>-PTEGMA) Block Copolymers: One-Pot Synthesis, Temperature Behavior, and Controlled Release of Paclitaxel

This paper introduces a new class of amphiphilic block copolymers created by combining two polymers: polylactic acid (PLA), a biocompatible and biodegradable hydrophobic polyester used for cargo encapsulation, and a hydrophilic polymer composed of oligo ethylene glycol chains (triethylene glycol methyl ether methacrylate, TEGMA), which provides stability and repellent properties with added thermo-responsiveness. The PLA-b-PTEGMA block copolymers were synthesized using ring-opening polymerization (ROP) and reversible addition–fragmentation chain transfer (RAFT) polymerization (ROP-RAFT), resulting in varying ratios between the hydrophobic and hydrophilic blocks. Standard techniques, such as size exclusion chromatography (SEC) and 1H NMR spectroscopy, were used to characterize the block copolymers, while 1H NMR spectroscopy, 2D nuclear Overhauser effect spectroscopy (NOESY), and dynamic light scattering (DLS) were used to analyze the effect of the hydrophobic PLA block on the LCST of the PTEGMA block in aqueous solutions. The results show that the LCST values for the block copolymers decreased with increasing PLA content in the copolymer. The selected block copolymer presented LCST transitions at physiologically relevant temperatures, making it suitable for manufacturing nanoparticles (NPs) and drug encapsulation-release of the chemotherapeutic paclitaxel (PTX) via temperature-triggered drug release mechanism. The drug release profile was found to be temperature-dependent, with PTX release being sustained at all tested conditions, but substantially accelerated at 37 and 40 °C compared to 25 °C. The NPs were stable under simulated physiological conditions. These findings demonstrate that the addition of hydrophobic monomers, such as PLA, can tune the LCST temperatures of thermo-responsive polymers, and that PLA-b-PTEGMA copolymers have great potential for use in drug and gene delivery systems via temperature-triggered drug release mechanisms in biomedicine applications