Hydroxyapatite composited PEEK with 3D porous surface enhances osteoblast differentiation through mediating NO by macrophage

The adverse immune response mediated by macrophages is one of the main factors that are prone to lead poor osseointegration of polyetheretherketone (PEEK) implants in clinic. Hence, endowing PEEK with immunomodulatory ability to avoid the adverse immune response becomes a promise strategy to promote bone repair. In this work, sulfonation and hydrothermal treatment were used to fabricate a three-dimensional porous surface on PEEK and hydroxyapatite composited PEEK. The hydroxyapatite composited PEEK with three-dimensional porous surface inhibited macrophages polarizing to M1 phenotype and down-regulated iNOS protein expression, which led to a nitric oxide concentration reduction in culture medium of mouse bone marrow mesenchymal stem cells (mBMSCs) under co-culture condition. The decrease of nitric oxide concentration could help to increase bone formation related OSX and ALP genes expressions and decrease bone resorption related MMP-9 and MMP-13 genes expressions via cAMP-PKA-RUNX2 pathway in mBMSCs. In summary, the hydroxyapatite composited PEEK with three-dimensional porous surface has the potential to promote osteogenesis of PEEK through immunomodulation, which provides a promising strategy to improve the bone repair ability of PEEK.

Elastic Nanofibrous Membranes for Medical and Personal Protection Applications: Manufacturing, Anti-COVID-19, and Anti-Colistin Resistant Bacteria Evaluation

Herein, in the present work two series of thermoplastic polyurethane (TPU) nanofibers were manufactured using the electrospinning techniques with ZnO and CuO nanoparticles for a potential use as an elastic functional layer in antimicrobial applications. Percentages of 0%, 2 wt%, and 4 wt% of the nanoparticles were used. The morphological characterization of the electrospun TPU and TPU/NPs composites nanofibers were observed by using scanning electron microscopy to show the average fiber diameter and it was in the range of 90–150 nm with a significant impact of the nanoparticle type. Mechanical characterization showed that TPU nanofiber membranes exhibit excellent mechanical properties with ultra-high elastic properties. Elongation at break reached up to 92.5%. The assessment of the developed nanofiber membranes for medical and personal protection applications was done against various colistin resistant bacterial strains and the results showed an increment activity by increasing the metal oxide concentration up to 83% reduction rate by using TPU/ZnO 4% nanofibers against K. pneumoniae strain 10. The bacterial growth was completely eradicated after 8 and 16 h incubation with TPU/ZnO and TPU/CuO nanofibers, respectively. The nanofibers SEM study reveals the adsorption of the bacterial cells on the metal oxides nanofibers surface which led to cell lysis and releasing of their content. Finally, in vitro study against Spike S-protein from SARS-CoV-2 was also evaluated to investigate the potent effectiveness of the proposed nanofibers in the virus deactivation. The results showed that the metal oxide concentration is an effective factor in the antiviral activity due to the observed pattern of increasing the antibacterial and antiviral activity by increasing the metal oxide concentration; however, TPU/ZnO nanofibers showed a potent antiviral activity in relation to TPU/CuO.

Reactivity Model as a Tool to Compare the Combustion Process in Aviation Turbine Engines Powered by Synthetic Fuels

The paper aims to verify the thesis that the reactivity model, developed in earlier research, can be used to compare the fuels combustion processes in turbine engines, which is important for predicting the behavior of different alternative fuels in combustion process. Synthetic blending components from alcohol to jet and hydroprocessed esters and fatty acids technologies and their blends with conventional jet fuel were used in tests. The undertaken laboratory tests reveal the differences between the properties of the tested fuels. Bench tests were carried out on a test rig with a miniature turbojet engine, according to authorial methodology. For each blend, on selected points of rotational speed the carbon oxide concentration in the exhaust gases was recorded. The obtained results allowed the formulation of empirical power functions describing relations between carbon oxide concentration and fuel mass flow rate. Based on general assumptions, the reactivity model was adopted to compare the combustion processes of the different fuels in turbine engines. The directions of further research on the development of the proposed model were indicated.

CFD-based simulation to reduce greenhouse gas emissions from industrial plants

Greenhouse gas (GHG) pollution is considered one of the challenging concerns in industrial plants, and to emit the appropriate designation in nitrogen oxide reduction, it is required to implement proper numerical simulation procedures. In this study, ANSYS Fluent® software is used as dynamic software to solve heat and mass flow transfer numerically by considering non-structured networks for complex geometries. Dry nitrogen oxide burners have an additional thermocouple to provide an extra fuel pathway to combine with air. Then, standard K-ε is used in the numerical simulations to calculate thermal efficiency in combustion processes for turbulent flow regimes. It can cause the removal of 50% of nitrogen oxide into the atmosphere. Furthermore, by the increase of temperature, nitrogen oxide concentration has been increased in the system. After 1975 K, Fuel has been changed to dry fuel, and therefore nitrogen oxide concentration increased because the steam can provide a relatively non-combustible compound increase than fuel. On the other hand, regarding the water volume increase at inlet steam, nitrogen oxide volume percentage has been decreased dramatically, especially in the first periods of water volume increase. Consequently, when the steam percentage is increased instead of water, nitrogen oxide reduction is increased. Moreover, our simulation results have a proper match with Gibbs energy equilibrium.

Growth and Gas Exchange Responses of Maize and Banana Plants in an Intercrop with Agroforestry Tree Species in Vihiga County, Kenya

Agroforestry trees have been reported to improve soil fertility through nitrogen fixation, coupled with leaves and twig decomposition. High human population pressure in Vihiga County has led to reduced land area under farming. This has resulted into increased demand for food and consequently forced smallholder farmers in the region to carry out poor farming practices such as continuous cultivation and clearing of trees to avail more land for crop production. The poor farming practices have occasioned severe land degradation, climate change and reduced farm productivity. However, it is not known how intercropping maize and banana with Sesbania sesban, Calliandra calothyrsus and Leucaena diversifolia impacts on the growth and gas exchange parameters of maize and banana. The objective of this study was to determine the effect of intercropping agroforestry tree species with maize and banana on maize and banana height, leaf area, number of leaves, stem diameter, intercellular Carbon (IV) oxide concentration, transpiration rate and net photosynthesis in Vihiga County. The study was conducted at Maseno university farm located in Vihiga County in Kenya. The Williams varieties of banana of the same age were obtained from KALRO-Thika. Seeds of selected agroforestry trees were obtained from KEFRI – Muguga, planted in a seedbed and the seedlings raised in nurseries before being transplanted in the study plots. Hybrid maize seed (H513) was purchased from an agrovet. Banana holes were dug 2x2 feet, 20 Kg of decomposed cow dung manure + 20 Kg of top soil + 200g of NPK fertilizer added in each banana hole before planting. A Randomized Complete Block Design (RCBD) with 3 replications was used with seven treatment levels of unfertilized Maize (M), Banana (B), Maize + Banana + Calliandra (MBC), Maize+ Banana+ Leucaena (MBL), Maize+ Banana+ Sesbania (MBS), Maize + Banana (MB) and Fertilized Maize (MF). Maize was planted at 0.75 m inter row by 0.3 m spacing. Fifteen (15) tagged maize and four (4) banana plants in each plot were sampled for measurement of height, number of green leaves, leaf area, stem diameter, intercellular Carbon (IV) oxide concentration, transpiration rate and net photosynthetic rate. The data was subjected to Analysis of Variance using Genstat statistical package version 15.2. Means were separated using Fischers’ protected LSD test at 95% confidence level. The MBS treatment showed higher growth in terms of height, leaf area, number of leaves and stem diameter throughout the study period. Increased growth seen under fertilized maize was not significantly different from those under MBS. Gas exchange responses had no significant differences (p≤0.05) among most treatments. However, agroforestry tree species had shown higher intercellular Carbon (IV) oxide concentration, transpiration rates and net photosynthesis of maize and banana plants. Sesbania sesban reported maximum intercellular Carbon (IV) oxide concentration, transpiration rates and net photosynthesis as compared to those treatments without agroforestry trees. Therefore, incorporating nitrogen-fixing trees in farming could have a positive impact on growth, increased carbon (IV) oxide intake, transpiration rates and net photosynthetic rate. Sesbania sesban promoted growth and recorded higher gas exchange parameters of maize and banana. These findings may be used to advice smallholder farmers of Vihiga County on the best intercropping system and agroforestry tree species to adopt for maximum maize and banana yield.