Biodegradable hydrogels based on chitosan and pectin for cisplatin delivery

Preparation of stable hydrogels using physically (electrostatically) interacting charge-complementary polyelectrolyte chains seems to be more attractive from a practical point of view than the use of organic crosslinking agents. In this work natural polyelectrolytes—chitosan and pectin—were used, due to their biocompatibility and biodegradability. The biodegradability of hydrogels is confirmed by experiments with hyaluronidase as an enzyme. It has been shown that the use of pectins with different molecular weights makes it possible to prepare hydrogels with different rheological characteristics and swelling kinetics. These polyelectrolyte hydrogels loaded with cytostatic cisplatin as a model drug provide an opportunity for its prolonged release, which is important for therapy. The drug release is regulated to a certain extent by the choice of hydrogel composition. The developed systems can potentially improve the effects of cancer treatment due to the prolonged release of cytostatic cisplatin

Osteoconductive properties of carbon fibre implants used in surgery of spine injuries and disorders (case report)

Purpose To assess osteoconductive properties of carbon fibre implants used in surgery of spine injuries and disorders. Materials and methods Two clinical cases from a multicentre prospective study on nanostructured carbon fibrous implants applied for a variety of spinal pathology are presented. Results The usage of highly porous carbon fibre implant resulted in bone and carbon fusion in the clinical instances whereas implants with a residual porosity of 7–12 % showed no fusion between bone and carbon. The patients had satisfactory clinical condition and quality of life. Discussion Carbon fibrous implant characteristics are close to those of bone tissue, being inert and osteoconductive along with high mechanical strength that ensure bone and carbon fibrous fusion with highly porous implan

Interpretation of Signals Recorded by Ocean-Bottom Pressure Gauges during the Passage of Atmospheric Lamb Wave on 15 January 2022

The eruption of the Hunga Tonga–Hunga Ha’apai volcano on 15 January 2022 was the first powerful explosive eruption in history to be recorded with high quality by a wide range of geophysical equipment. The atmospheric Lamb wave caused by the explosion repeatedly circled the Earth and served as one of the reasons for the formation of tsunami waves. In this paper, the Lamb wave manifestations are analyzed in the recordings of tsunamimeters, i.e., in data from DONET and DART pressure sensors located in the area of the Japanese Islands. The work is aimed at studying the physics of the formation of pressure variations at the ocean floor in order to develop a method for isolating free gravity waves in records obtained by bottom pressure sensors. Within the framework of shallow water theory, an analysis of the response of the water layer to the atmospheric Lamb wave was performed. This response combines a forced perturbation, the amplitude of which depends on the depth of the ocean, and free gravity waves arising as a result of the restructuring of the forced perturbation on the submarine slopes. Analytical formulas are given for the amplitude and energy of the forced perturbation and free waves arising at the depth jump. With the aid of numerical simulation, the finite length of a slope was revealed to significantly affect the parameters of free waves when exceeding 50 km. The analysis of in situ data (DONET, DART) confirms the validity of theoretical concepts presented in the work. In particular, it is shown that variations of bottom pressure in the deep ocean exceed the amplitude of atmospheric pressure fluctuations in the Lamb wave

Automatic Tsunami Hazard Assessment System: “Tsunami Observer”

The current prototype of a fully automatic earthquake tsunami hazard assessment system, “Tsunami Observer”, is described. The transition of the system to the active phase of operation occurs when information about a strong earthquake (Mw ≥ 6.0) is received. In the first stage, the vector field of coseismic displacements of the Earth’s crust is calculated by using the Okada formulas. In the calculations, use is made of data on the coordinates, the seismic moment, the focal mechanism, and the depth of the earthquake, as well as empirical patterns. In the second stage, the initial elevation of the water surface at the tsunami’s focus is determined with the vector field of coseismic displacements of the bottom and the distribution of ocean depths, and the earthquake’s potential energy is calculated. In the third stage, the intensity of the tsunami is estimated on the Soloviev–Imamura scale in accordance with the magnitude of the potential energy by using the empirical relationship that is obtained as a result of a statistical analysis of historical tsunami events. In the final stage, if the energy exceeds the critical value of 109 J, a numerical simulation of the tsunami is performed, which allows the determination of the predominant directions of wave energy propagation and estimation of the runup height on the nearest coast. In this work, data on the operation of the system over the last 3 years are presented

Automatic Tsunami Hazard Assessment System: “Tsunami Observer”

The current prototype of a fully automatic earthquake tsunami hazard assessment system, “Tsunami Observer”, is described. The transition of the system to the active phase of operation occurs when information about a strong earthquake (Mw ≥ 6.0) is received. In the first stage, the vector field of coseismic displacements of the Earth’s crust is calculated by using the Okada formulas. In the calculations, use is made of data on the coordinates, the seismic moment, the focal mechanism, and the depth of the earthquake, as well as empirical patterns. In the second stage, the initial elevation of the water surface at the tsunami’s focus is determined with the vector field of coseismic displacements of the bottom and the distribution of ocean depths, and the earthquake’s potential energy is calculated. In the third stage, the intensity of the tsunami is estimated on the Soloviev–Imamura scale in accordance with the magnitude of the potential energy by using the empirical relationship that is obtained as a result of a statistical analysis of historical tsunami events. In the final stage, if the energy exceeds the critical value of 109 J, a numerical simulation of the tsunami is performed, which allows the determination of the predominant directions of wave energy propagation and estimation of the runup height on the nearest coast. In this work, data on the operation of the system over the last 3 years are presented

The Yukagir Bison:The exterior morphology of a complete frozen mummy of the extinct steppe bison, Bison priscus from the early Holocene of northern Yakutia, Russia

The paper presents analyses of the exterior morphology of one of the extinct and dominating species of the Late Pleistocene megafauna of Eurasia, the steppe bison, Bison priscus. The frozen mummy of the Yukagir Bison found in northern Yakutia, Russia represents the most complete specimen of this species in the world. It belongs to a young, 4.1-4.5 year old male, which dates back about 10,500 cal BP. The analyses revealed that the overall size of this specimen was comparable to a 6-year old European and American bison. Its horn spread falls within the upper limits of B. bison athabascae and B. bison bison males, as well as within the average sizes of B. priscus occidentalis from East Siberia and North America. While most of the not fully-grown Yukagir Bison body size fell within the average parameters of both grown modern species, the body and hind foot lengths were closer to the lower limits of the European bison. The color and hair pattern appeared to be close to the Blue Babe mummy (B. priscus) and modern Wood bison (modern morphotype of B. bison athabascae) and European (B. bonasus) bison. The geological age of the Yukagir Bison, along with the data from other specimens indicate that this species, which survived the Pleistocene-Holocene boundary, became rare but was still widely distributed in the northern part of centraleastern Siberia until about 8000 years ago. The juxtaposed data from arctic latitude sediments and the Bison priscus stomach content pollen indicate that it was selective grazer in the environment dominated by unfavorable shrub and forest-tundra vegetation. The scarce Holocene steppe bison remains in Eastern Siberia reflects the dramatic decrease of suitable habitats and pastures during the early Holocene climatic optimum in the high Arctic, which was a major factor of irreversible population fragmentation and decline leading to the species' extinction. (C) 2015 Elsevier Ltd and INQUA. All rights reserved