Short-term changes in thermal conditions and active layer thickness in the tundra of the Kaffiøyra region, NW Spitsbergen

This article describes and discusses the results of observations concerning short-term changes in the thermal conditions and the thickness of the active layer in a test field located in the tundra of the Kaffiøyra (NW Spitsbergen) during the summer season of 2015. One of the objectives was to find a correlation between the dynamic of the changes and the local topography. In recent years, thawing of the active layer in the Kaffiøyra region has been considerably varied in individual summer seasons. The test field area was 100 square meters, comprised 36 measurement points and was situated at approximately 3 m a.s.l. in the tundra. The measurements of the thickness and temperature of the active layer were carried out in July, August and early September of 2015. The greatest thickness of the active layer in the tundra was found near the moraine, in the area with the sharpest slope (156 cm to 212 cm). Ground temperatures were observed to follow the prevailing weather conditions with a delay, which amounted to about 24 h at a depth of 25 cm, and as much as 48 h at a depth of 75 cm. A greater thickness of the active layer was found in the western part of the test field, in the vicinity of a tidal channel, and in the eastern part of the field, bordering on the foot of the Aavatsmarkbreen’s moraine. A considerable sloping of the land, combined with increased surface runoff and infiltration at the time of precipitation, makes the water penetrating into the active layer increase its temperature. This demonstrates that the local land forms (tidal channels and terminal moraines) have a substantial influence on the extent and rate of changes which occur in the active layer.

SUBMARINE EVIDENCE OF THE LATE WEICHSELIAN MAXIMUM EXTENT AND THE LITTLE ICE AGE (LIA) GLACIER LIMITS IN THE ST. JONSFJORDEN REGION (SVALBARD)

The paper presents the results of bathymetric mapping of selected tidewater glaciers in the St. Jonsfjorden (Svalbard) between 2004 and 2007. We also used the bathymetric data collected by the Norwegian Hydrographic Service (NHS) as well as the shaded relief images based on them. The most clearly visible traces in submarine marginal zones of the glaciers come from the Little Ice Age (LIA), i.e. the cooling period which in the area of St. Jonsfjorden might have ended no later than about 1900. At the beginning of the 20th century, i.e. during a warm period, the glaciers of St. Jonsfjorden reached their maximums. The youngest traces in the seafloor of the fjord and the bays date from this period, similar to the case of the land marginal zones. In front of the cliff of the Dahl Glacier there is a clearly visible zone of submarine moraines. It finishes exactly along the line of the LIA maximum. The sea-floor relief of the fjord and bays shows traces which we interpret as having been formed during the Late Weichselian (13–10 ka B.P.). At that time, the Dahl Glacier advanced onto the northern part of Hermansenøya; its main stream passed to the north of the island. Simultaneously, the Konow-Osborne Glacier terminated 2 to 4 km from the fjord mouth, leaving about 15 km2 of the fjord ice-free.

(Bio)degradable polymeric materials for sustainable future—Part 3: Degradation studies of the PHA/wood flour-based composites and preliminary tests of antimicrobial activity

© 2020 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/ma13092200The need for a cost reduction of the materials derived from (bio)degradable polymers forces research development into the formation of biocomposites with cheaper fillers. As additives can be made using the post-consumer wood, generated during wood products processing, re-use of recycled waste materials in the production of biocomposites can be an environmentally friendly way to minimalize and/or utilize the amount of the solid waste. Also, bioactive materials, which possess small amounts of antimicrobial additives belong to a very attractive packaging industry solution. This paper presents a study into the biodegradation, under laboratory composting conditions, of the composites that consist of poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate)] and wood flour as a polymer matrix and natural filler, respectively. Thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy were used to evaluate the degradation progress of the obtained composites with different amounts of wood flour. The degradation products were characterized by multistage electrospray ionization mass spectrometry. Also, preliminary tests of the antimicrobial activity of selected materials with the addition of nisin were performed. The obtained results suggest that the different amount of filler has a significant influence on the degradation profile.Published onlin

Three-Dimensional Printed PLA and PLA/PHA Dumbbell-Shaped Specimens: Material Defects and Their Impact on Degradation Behavior

The use of (bio)degradable polymers, especially in medical applications, requires a proper understanding of their properties and behavior in various environments. Structural elements made of such polymers may be exposed to changing environmental conditions, which may cause defects. That is why it is so important to determine the effect of processing conditions on polymer properties and also their subsequent behavior during degradation. This paper presents original research on a specimen’s damage during 70 days of hydrolytic degradation. During a standard hydrolytic degradation study of polylactide and polylactide/polyhydroxyalkanoate dumbbell-shaped specimens obtained by 3D printing with two different processing build directions, exhibited unexpected shrinkage phenomena in the last degradation series, representing approximately 50% of the length of the specimens irrespective of the printing direction. Therefore, the continuation of previous ex-ante research of advanced polymer materials is presented to identify any possible defects before they arise and to minimize the potential failures of novel polymer products during their use and also during degradation. Studies on the impact of a specific processing method, i.e., processing parameters and conditions, on the properties expressed in molar mass and thermal properties changes of specimens obtained by three-dimensional printing from polyester-based filaments, and in particular on the occurrence of unexpected shrinkage phenomena after post-processing heat treatment, are presented

State-of-the-art of transcatheter treatment of aortic valve stenosis and the overview of the InFlow project aiming at developing the first Polish TAVI system

Initial experience of transcatheter aortic valve implantation (TAVI) or replacement (TAVR) has ap-peared as a promising minimally invasive technology for patients disqualified from surgical treatment (SAVR). Safety and efficacy of TAVI has been analyzed and assessed through numerous registries and trials. Furthermore, results obtained from comparative TAVI vs. SAVR trials proved that both treat¬ments can be considered equal in terms of post-procedural mortality and morbidity in high-risk, as well as lower risk patients. However, there are still some issues that have to be addressed, such as higher chance of paravalvular leakage, vascular injuries, conduction disturbances, malpositioning and the yet unmet problem of insufficient biological valves durability. Recent technological developments along with the learning curve of operators prove a great potential for improvement of TAVI and a chance of surpassing SAVR in various groups of patients in the near future. In pursuit of finding new solutions, the CardValve Consortium consisting of leading scientific and research institutions in Poland has been created. Under the name of InFlow and financial support from the National Center for Research and Development, they have started a project with the aim to design, create and implement into clinical practice the first, Polish, low-profile TAVI valve system, utilizing not only biological but also artificial, polymeric-based prosthesis. This review focuses on current developments in TAVI technologies including the InFlow project

Long-term bio-functional performance of a novel, self-positioning balloon expandable transcatheter biological aortic valve system in the ovine aortic banding model

Background: The aim of the study was to evaluate bio-functionality of a novel, proprietary balloon-expandable biological transcatheter aortic valve implantation (TAVI) system (InFlow, CardValve Consortium, Poland) in an ovine model of aortic banding. Methods: Surgical ascending aorta banding was created in 21 sheep. Two weeks later, 18 biological valves were implanted within the model using 15–16 F InFlow TAVI systems and carotid cut-down approach. Follow-up transthoracic echocardiography was performed at 30, 90, and 180-day. At designated time, animals were euthanized and valves harvested for analysis. Results: All sheep survived the banding procedure. There were 4 (22%) procedure related deaths within a 7-day period. During the observation an additional 2 sheep died. In one, the valve dislocated after the procedure — the animal was excluded. Two animals completed 30-day follow up, five 90-day follow-up and four terminal follow-up of 180 days. Valves examined via transesophageal echocardiography showed proper hemodynamic parameters without evidence of structural valve deterioration. The maximum and average flow gradients at 180 days were 31.4 (23.3–37.7) and 17.5 (13.1–20.2) mmHg, respectively. There was one case of moderate insufficiency and no case of perivalvular leaks. By histopathology, there were no inflammation, thrombosis, nor calcifications in any tested valves at long-term follow-up. Neointimal coverage of stent struts increased with time from basal part in “early” groups to nearly 3/4 of stent length in the 180-day group. The pannus tissue showed maturation that increased with time with no stenotic “collar” visible in orthotopically implanted valves. Conclusions: The study showed good hemodynamic performance, durability and biocompatibility of the novel biological THV

A comparative study of three-dimensional printing directions: The degradation and toxicological profile of a PLA/PHA blend

The use of biobased plastics is of great importance for many applications. Blending thermoplastic polylactide (PLA) with polyhydroxyalkanoate (PHA) enables the formulation of a more mechanically powerful material and this enables tailored biodegradation properties. In this study we demonstrate the 3D printing of a PLA/PHA blend as a potential candidate for biocompatible material applications. The filament for 3D printing consisted of PHA, which contains predominantly 3-hydroxybutyrate units and a small amount of 3-hydroxyvalerate units, as revealed by multistage mass spectrometry (ESI-MSn). This research found that the properties of 3D printed species before and during abiotic degradation are dependent on printing orientation. Furthermore, the 3D printed specimens exhibited good biocompatibility with HEK293 cells, indicating real promise as biological scaffolds for tissue engineering applications

The role of Civic Militia against antigovernment demonstrations during Poznań June 1956, March 1968, December 1970.

Niniejsza praca poświęcona została działalności Milicji Obywatelskiej przeciwko antyrządowym wystąpieniom w latach 1944 - 1970. Praca przedstawia sytuację wewnętrzną państwa polskiego po zakończeniu działań militarnych drugiej wojny światowej, opisuje wygląd najważniejszych elementów składających się na sfery życia polityczno, ekonomiczno, społecznego kraju oraz ich kształtowanie się na przestrzeni lat. Punktem centralnym pracy są wystąpienia antyrządowe w latach 1944 - 1970 przeciwko władzy centralnej. W opracowaniu przedstawiono przyczyny, przebieg oraz konsekwencje wynikające z demonstracji przeprowadzonych przeciw władzy partyjnej. Ponadto, dokonano charakterystyki Milicji Obywatelskiej, jej genezę, wewnętrzną strukturę organizacyjną oraz zakres działań kształtujący się na przestrzeni lat.Presented thesis has been dedicated to activities of Civic Militia against antigovernment demonstrations during 1944 - 1970. The thesis shows the inner situation of Poland after the end of the Second World War. It describes the most important elements consisting of political, economic and social spheres of the country as well as their gradual change over the years. The core of the thesis presents the origins, the course and the results of public manifestations against central authorities. Moreover, the thesis describes the history, internal organization structure and range of duties which were being changed over the years

Measurement of Simple Reaction Time of the Cyclist in the Laboratory and Natural Environment Condition

The most commonly used reaction time tests within the athlete community require appropriate testing conditions and equipment, most frequently laboratory ones, which are not suitable for testing athletes in their natural environment and do not fully represent athletes’ natural capabilities and the influence of the surrounding environment. Therefore, this study’s goal is to compare the simple reaction times (SRTs) of cyclists during tests in laboratory conditions and in natural cycling surroundings. The young cyclists (55 participants) took part in the study. The SRT was measured in a quiet laboratory room with the use of the special device. During riding and standing with a bike outdoors, the necessary signal was captured and transmitted by a folic tactile sensor (FTS) and an extra intermediary circuit (both invented by our team member) connected to a muscle activity measurement system (Noraxon DTS Desktop, Scottsdale, AZ, USA). The results showed that external conditions significantly affect the SRT, with it being the longest when riding and the shortest if measured in an isolated laboratory room, but without an effect of gender. Typically, men have a shorter reaction time, but our result supports other observations, where people with an active lifestyle show no sex differentiation in SRT. The proposed FTS with an intermediary circuit allowed us to measure SRT with the use of non-dedicated equipment and avoid buying a new one for a single specific use