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Background: Dental tissue engineering (DTE) is an inspiring biological approach to replacing lost teeth. The strength of the differentiation of basic endometrial cells to ameloblasts is yet to be fully understood. Moreover, the construction of a scaffold, upon which ameloblasts can both grow and replicate, has been a challenge in DTE. Methods: This is an experimental study. Basic endometrial cells were first isolated and cultured before induction of differentiation to ameloblast cells by adjacency to mesenchymal rat cells and application of fibroblast growth factor 8. Hydroxyapatite nanoparticles were synthesized by freeze‑drying method. The nanocomposite collagen and hydroxyapatite scaffold were synthesized by the solvent casting method. Finally, the amyloblast cells were implanted into the hydroxyapatite and collagen nanocomposite scaffold. Results: The success of cell differentiation was confirmed through staining using specific antibodies against ameloblastin and amelogenin markers. Expression of ameloblast‑specific mRNAs, such as ameloblastins, amelogenins, and cytokeratin 14 was detected in the differentiated cells. Alizarin red staining clearly illustrates mineralization nodules in the differentiated cells. Staining against specific ameloblast markers showed that the differentiated ameloblast cells are expressed on the scaffold, unlike the control group. Conclusion: Based on the findings of this study, basic endometrial cells are capable of expressing the traits of ameloblast cells. The scaffold used in the present study conforms to most criteria used for dental tissue reconstruction and can be applied in DTE. [ABSTRACT FROM AUTHOR]

Purpose: Anaerobic digestion is a promising technology for simultaneous treatment of biodegradable organic matter of municipal solid waste (MSW) and production of renewable energy. Mixing modes and temperature have influences on biogas production in anaerobic digesters treating MSW. Therefore, in this study, digester was operated at different modes of mixing and temperatures to obtain design criteria. Methods: The experiments were carried out in a semi-continuous digester. In the first part of the investigation, temperature was set at 25, 28, 31 and 34 °C. During this step, digester content was mixed in an intermittent mode by mechanical mixers. In the second part of the study, mixing condition of the digester was set at various modes: continuous, intermittent (15 min on and 30 min off) and minimal (twice in a batch). Results: Digestion with a temperature in this range resulted in biogas yield of 0.23–0.33 m3 biogas/kg VS, with a methane content of 60.2–71.8% in biogas. The methane content and yield decreased with reduction of digestion temperature. However, this reduction was almost negligible from 34 to 31 °C. In addition, in comparison to intermittent mixing, continuous and minimal mixing modes reduced the biogas production by 40% and 50%, respectively. Therefore, in this digester greatest biogas yield of 0.33 ± 0.02 m3 biogas/kg VS were obtained at 34 °C and intermittent mixing mode. Conclusions: Based on the data obtained from this study, temperature in the range of 31–34 °C and intermittent mixing is suggested as a base for design purposes. [ABSTRACT FROM AUTHOR]

In this study, the effect of mixotrophic, heterotrophic, photoautotrophic (CO2 of air source), and photoautotrophic (bicarbonate source) cultivation of Chlorella vulgaris was investigated on microalgae growth rate and nutrient removal under different kinds of nitrogen sources. The highest N-NH3+, N-NO3−, P-PO43− (in ammonium source), and P-PO43− (in nitrate source) removal efficiency (87.28 ± 0.89, 70.00 ± 1.20, 87.00 ± 3.10, and 78.10 ± 1.95%, respectively) was reached in the mixotrophic culture. In all cultivations, when nitrate was used as the nitrogen source, specific growth rate, biomass productivity, and specific oxygen production rate (SOPR) were higher than the one with ammonium source due to decreased pH. However, in all cultures except for photoautotrophic cultivation (in the CO2 of the air), nitrogen removal rates improved in the ammonium source. In addition, in both ammonium and nitrate source, the respiration activity of mixotrophic microalgae was higher than the photosynthetic activity of the cells. When CO2 was used as inorganic carbon, the specific growth rate of microalgae was lower than with the bicarbonate source. Based on the obtained results, mixotrophic conditions would be the most useful cultivation for application in N-rich wastewater treatment systems. [ABSTRACT FROM AUTHOR]

Microalgae are able to metabolize inorganic selenium (Se) to organic forms (e.g. Se-proteins); nevertheless at certain Se concentration culture growth is inhibited. The aim of this work was to confirm the hypothesis that the limit of Se tolerance in Chlorella cultures is related to photosynthetic performance, i.e. depends on light intensity. We studied the relation between the dose and irradiance to find the range of Se tolerance in laboratory and outdoor cultures. At low irradiance (250 µmol photons m s), the daily dose of Se below 8.5 mg per g of biomass (<20 µM) partially stimulated the photosynthetic activity (relative electron transport rate) and growth of Chlorella cultures (biomass density of ~1.5 g DW L) compared to the control (no Se added). It was accompanied by substantial Se incorporation to microalgae biomass (~0.5 mg Se g DW). When the Se daily dose and level of irradiance were doubled (16 mg Se g DW; 500 µmol photons m s), the photosynthetic activity and growth were stimulated for several days and ample incorporation of Se to biomass (7.1 mg g DW) was observed. Yet, the same Se daily dose under increased irradiance (750 µmol photons m s) caused the synergistic effect manifested by significant inhibition of photosynthesis, growth and lowered Se incorporation to biomass. In the present experiments Chl fluorescence techniques were used to monitor photosynthetic activity for determination of optimal Se doses in order to achieve efficient incorporation without substantial inhibition of microalgae growth when producing Se-enriched biomass. [ABSTRACT FROM AUTHOR]

In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem., Competing Interests: The authors declare there is no conflict., (© 2024 The Authors This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).)

Objectives: The purpose was to evaluate the impact of an oral health promotion program including supervised toothbrushing and educational packages for parents on parent's knowledge and oral health status of 6- to 7-year-old schoolchildren., Materials and Methods: A multi-stage cluster random sampling method was applied, and schools were allocated to intervention and control groups. After ethical clearance and baseline evaluation, an intervention package consisting of supervised toothbrushing at the school setting, an educational package for parents, and a home package containing toothbrush and fluoridated toothpaste (1000 parts-per-million) were delivered. A post-intervention evaluation was performed after one month on parents' oral health knowledge and oral hygiene of children using the Oral Hygiene Index Simplified (OHI-S). Schools were considered as a unit of randomization, and a generalized estimating equation (GEE) analysis was performed to apply the cluster effect. Descriptive and analytical analyses were performed using SPSS 22 software., Results: Overall, 701 subjects were re-examined (response rate of 95%). At the one-month follow-up, being in the intervention group (P<0.001, B=-0.028, 95% confidence interval (CI)= -0.33, -0.23) and having higher socioeconomic status [P=0.01, B=-0.12, 95% CI=-0.22, -0.03) were significantly associated with improved oral hygiene status. In the post-test evaluation, parents' knowledge improvement score regarding oral health in the intervention group was not statistically different from that of the controls (0.51 vs. 0.23). However, the ΔOHI-S improved in the post-test evaluation (-0.27±0.02 vs. 0.02±0.02; P<0.001)., Conclusion: Children showed improved oral hygiene status, as measured by the OHI-S, after the program consisting of supervised toothbrushing., Competing Interests: CONFLICT OF INTEREST STATEMENT None declared, (© 2020 The Authors. Published by Tehran University of Medical Sciences.)