Mechanical, Structural, and Biological Properties of Chitosan/Hydroxyapatite/Silica Composites for Bone Tissue Engineering

The aim of this work was to fabricate novel bioactive composites based on chitosan and non-organic silica, reinforced with calcium β-glycerophosphate (Ca-GP), sodium β-glycerophosphate pentahydrate (Na-GP), and hydroxyapatite powder (HAp) in a range of concentrations using the sol–gel method. The effect of HAp, Na-GP, and Ca-GP contents on the mechanical properties, i.e., Young’s modulus, compressive strength, and yield strain, of hybrid composites was analyzed. The microstructure of the materials obtained was visualized by SEM. Moreover, the molecular interactions according to FTIR analysis and biocompatibility of composites obtained were examined. The CS/Si/HAp/Ca-GP developed from all composites analyzed was characterized by the well-developed surface of pores of two sizes: large ones of 100 μm and many smaller pores below 10 µm, the behavior of which positively influenced cell proliferation and growth, as well as compressive strength in a range of 0.3 to 10 MPa, Young’s modulus from 5.2 to 100 MPa, and volumetric shrinkage below 60%. This proved to be a promising composite for applications in tissue engineering, e.g., filling small bone defects

Carbon Dioxide Gasification Kinetics of Char from Rapeseed Oil Press Cake

Rapeseed oil press cake (RPC) is an abundantly available and renewable agricultural waste material for the production of fuels or chemicals. In this study, the rates of carbon dioxide gasification of rapeseed oil press cake char were measured by thermogravimetric analysis measurements performed at various temperatures (800–900 °C) and CO2 mole fractions (0.10–1.00). The char was obtained by slow pyrolysis, where the dried RPC was decomposed at a temperature range of 1000 °C to obtain char free of impurities that can affect the measurements. The random pore model appeared to be suitable for describing the effect of conversion on the reaction rate. The temperature, CO2, and concentration dependence of the reaction rate were given by the Arrhenius equation and a power law (nth order) correlation. The kinetic parameters based on the experimental data were determined by a two-step estimation procedure. For the experimental conditions employed in this study, the parameters E and n were 222.1 kJ/mol and 0.57, respectively

Pyrolysis of Rapeseed Oil Press Cake and Steam Gasification of Solid Residues

A deoiled rapeseed press cake (RPC) was pyrolyzed by heating at a slow heating rate to 1000 °C in a fixed bed reactor, and the produced char was then gasified to obtain data for the kinetic modeling of the process. The gasification experiments were performed in a thermogravimetric analyzer (TGA) under steam/argon mixtures at different temperatures (750, 800 and 850 °C) and steam mole fractions (0.17 and 0.45). The three most commonly used gas-solid kinetic models, the random pore model, the volumetric model and the shrinking core model were used to describe the conversion of char during steam gasification. The objective of the kinetic study was to determine the kinetic parameters and to assess the ability of the models to predict the RPC conversion during steam gasification. A TGA-MS analysis was applied to assess the composition of the product gas. The main steam gasification product of the RPC was hydrogen (approximately 60 mol % of the total product). The volumetric model was able to accurately predict the behavior of the RPC char gasification with steam at temperatures of 750–850 °C and steam concentrations less than 0.45 mole fraction. The activation energy and the reaction order with respect to steam were equal to 166 kJ/mol and 0.5, respectively, and were typical values for the gasification of biomass chars with stea

A MOOSE RECOVERY PLAN FOR POLAND: MAIN OBJECTIVES AND TASKS

Hunting statistics showed that moose (Alces alces) numbers in Poland declined from 5,400 animals in 1991 to 1,718 in 2000. A nation-wide ban on moose hunting was imposed in 2001 in response to this decline in moose abundance. The main purpose of this paper is to outline a moose recovery plan in Poland by using verification of hunting records related to moose population numbers, collecting data on population demographic variables, and understanding moose habitat preferences. During 1998-2002 in the forest habitat of north eastern Poland (total area: 311,400 ha) a line intercept snow track index and plot sampling were used to estimate moose population numbers at 276 animals. It was shown that the population census in this area carried out by hunters in this period through a guess-estimate method overestimated the moose population by 46.0%. Research in Augustowska Forest (110,200 ha) shows that the autumn recruitment rate was 64.4 calves per 100 cows, and the ratio of cows to bulls was 1.34. Analysis of moose population dynamics during 4 hunting seasons (1998-2001) shows that the maximum sustainable harvest is about 30% of population numbers estimated in February. Habitat selection by moose was tested using Bailey's 95% simultaneous confidence intervals. Moose preferred habitats in bog and wet sites dominated by deciduous and mixed forests. The decline in moose populations in Poland over 20 years was caused by overestimation of population numbers and over-harvest. It is suggested that a moose recovery program in Poland should be started by locating 2 large moose management/conservation units where moose population numbers should be estimated by reliable methods, and sustained harvest would then maintain a viable moose population. At the same time, forestry in moose wintering areas should stimulate deciduous browse production as well as providing estimates of forest damage caused by moose using different standards than those applied in lowland commercial forests

Role of WRKY Transcription Factors in Regulation of Abiotic Stress Responses in Cotton

Environmental factors are the major constraints in sustainable agriculture. WRKY proteins are a large family of transcription factors (TFs) that regulate various developmental processes and stress responses in plants, including cotton. On the basis of Gossypium raimondii genome sequencing, WRKY TFs have been identified in cotton and characterized for their functions in abiotic stress responses. WRKY members of cotton play a significant role in the regulation of abiotic stresses, i.e., drought, salt, and extreme temperatures. These TFs either activate or repress various signaling pathways such as abscisic acid, jasmonic acid, salicylic acid, mitogen-activated protein kinases (MAPK), and the scavenging of reactive oxygen species. WRKY-associated genes in cotton have been genetically engineered in Arabidopsis, Nicotiana, and Gossypium successfully, which subsequently enhanced tolerance in corresponding plants against abiotic stresses. Although a few review reports are available for WRKY TFs, there is no critical report available on the WRKY TFs of cotton. Hereby, the role of cotton WRKY TFs in environmental stress responses is studied to enhance the understanding of abiotic stress response and further improve in cotton plants

Fire Safety of Healthcare Units in Conditions of Oxygen Therapy in COVID-19: Empirical Establishing of Effects of Elevated Oxygen Concentrations

Large-scale usage of oxygen therapy (OT) may lead to increased oxygen concentrations (OC) in places where COVID-19 patients are treated. The aim of the study was to establish in an empirical way the OC in COVID-19 at the patient’s bedside and to assess the relationships and reactions that occur during OT in an uncontrolled oxygen-enriched environment. We analyzed and took into account the OC, the technical conditions of the buildings and the air exchange systems. Based on the results, we performed a Computational Fluid Dynamics analysis to assess evacuation conditions in the event of a fire outbreak in the COVID-19 zone. A total of 337 measurements of OC were carried out, and three safety thresholds were then defined and correlated with fire effects. The highest ascertained oxygen concentration was 25.2%. In the event of a fire outbreak at 25.2% oxygen in the atmosphere, the response time and evacuation of medical staff and patients is no longer than 2.5 min. Uncontrolled oxygen enrichment of the environment threatens the safety of medical staff and patients in COVID-19 hospitals

The Role of Digital Soil Information in Assisting Precision Soil Management

Soil information is the basis for the site-specific management of soils. The study aimed to digitize soil information and classify it into soil mapping units (SMUs) using geostatistics. The study area was grouped into 12 SMUs, or management zones. The pH of the soils ranged from 7.3 in SMU2 to 8.6 in SMU5. Most SMUs exhibited low total nitrogen (TN) that could be attributed to very low soil organic carbon (SOC) in the soils. Available phosphorus (AvP) was very low in all the mapping units. The exchangeable K varied between 0.12 cmol(+) kg−1 (SMU7) and 0.95 cmol(+) kg−1 (SMU10). SMU12 was identified as marginally sodic and at a high risk of developing severe alkalinity unless possible management measures are implemented. Our findings show that a lack of soil information causes an imbalance between soil requirements and external nutrient inputs, negatively affecting crop production. Therefore, high-resolution digital soil information can assist the site-specific application of soil nutrients and amendments based on spatial variability in line with soil requirements

The Role of Digital Soil Information in Assisting Precision Soil Management

Soil information is the basis for the site-specific management of soils. The study aimed to digitize soil information and classify it into soil mapping units (SMUs) using geostatistics. The study area was grouped into 12 SMUs, or management zones. The pH of the soils ranged from 7.3 in SMU2 to 8.6 in SMU5. Most SMUs exhibited low total nitrogen (TN) that could be attributed to very low soil organic carbon (SOC) in the soils. Available phosphorus (AvP) was very low in all the mapping units. The exchangeable K varied between 0.12 cmol(+) kg−1 (SMU7) and 0.95 cmol(+) kg−1 (SMU10). SMU12 was identified as marginally sodic and at a high risk of developing severe alkalinity unless possible management measures are implemented. Our findings show that a lack of soil information causes an imbalance between soil requirements and external nutrient inputs, negatively affecting crop production. Therefore, high-resolution digital soil information can assist the site-specific application of soil nutrients and amendments based on spatial variability in line with soil requirements

Sustainable Development of Chitosan/Calotropis procera-Based Hydrogels to Stimulate Formation of Granulation Tissue and Angiogenesis in Wound Healing Applications

The formation of new scaffolds to enhance healing magnitude is necessarily required in biomedical applications. Granulation tissue formation is a crucial stage of wound healing in which granulation tissue grows on the surface of a wound by the formation of connective tissue and blood vessels. In the present study, porous hydrogels were synthesized using chitosan incorporating latex of the Calotropis procera plant by using a freeze–thaw cycle to stimulate the formation of granulation tissue and angiogenesis in wound healing applications. Structural analysis through Fourier transform infrared (FTIR) spectroscopy confirmed the interaction between chitosan and Calotropis procera. Latex extract containing hydrogel showed slightly higher absorption than the control during water absorption analysis. Thermogravimetric analysis showed high thermal stability of the 60:40 combination of chitosan (CS) and Calotropis procera as compared to all other treatments and controls. A fabricated scaffold application on a chick chorioallantoic membrane (CAM) showed that all hydrogels containing latex extract resulted in a significant formation of blood vessels and regeneration of cells. Overall, the formation of connective tissues and blood capillaries and healing magnitude decreased in ascending order of concentration of extract