The present study aimed to examine the effectiveness of the flipped classroom learning environment on learner's learning achievement and motivation, as well as to investigate the effects of flipped ...classrooms on learners with different achievement levels in learning mathematics concepts. The learning achievement and motivation were measured by the Mathematics Achievement Test (MAT) and Course Interest Survey (CIS), respectively. A pretest posttest quasi-experimental design was employed for this study. A total of 82 high-school students participated in this study, divided into experimental and control groups. The experimental group (41) was taught trigonometry using the flipped classroom method, while the control group (41) was taught by traditional teaching methods. The researchers employed independent sample t-test, analysis of covariance (ANCOVA), and multivariate analysis of variance (MANOVA) to analyze the data obtained. Findings indicated a significant difference in the learning achievement and motivation between the two groups, with students using the flipped classroom performing better. Further analysis showed a significant difference in the performance of low achievers in the experimental and control groups.
•We describe the dose–response curve for the impact of tree cover density on stress reduction.•We employed 6-min, 3-D videos of community street scenes as the nature treatment.•We measured skin ...conductance and salivary cortisol levels as measures of participants’ stress.•For men, the dose–response curve was an inverted-U shape.•For women, we found no relationship between tree cover density and stress reduction.
Although it is well established that exposure to nearby nature can help reduce stress in individuals, the shape of the dose–response curve is entirely unclear. To establish this dose–response curve, we recruited 160 individuals for a laboratory experiment. Participants engaged in the Trier Social Stress Test (TSST) to induce psychological stress, and were then randomly assigned to view one of ten, 6-min, 3-D videos of neighborhood streets. The density of tree cover in the videos varied from 1.7% to 62.0%. We measured their stress reactions by assessing salivary cortisol and skin conductance levels. Results show a clear disparity between women and men. For women, we found no relationship between varying densities of tree cover and stress recovery. For men, the dose–response curve was an inverted-U shape: as tree cover density increased from 1.7% to 24%, stress recovery increased. Tree density between 24% to 34% resulted in no change in stress recovery. Tree densities above 34% were associated with slower recovery times. A quadratic regression using tree cover density as the independent variable and a summary stress index as the dependent variable substantiated these results R2=.22, F (2, 68)=9.70, p<.001. The implications for our understanding of the impacts of nearby nature, and for the practice of planning and landscape architecture are discussed.
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•Resource efficiency is a key circular bioeconomy concept.•Microalgae based wastewater treatment results in beneficial biomass.•Outdoor open ponds with sufficient light supply ...enhances microalgal growth.•Nutrient dissipation by abiotic methods needs to be controlled.•Techno economic evaluation and LCA are required for effective implementation.
The basic concepts of circular bioeconomy are reduce, reuse and recycle. Recovery of recyclable nutrients from secondary sources could play a key role in meeting the increased demands of the growing population. Wastewaters of different origin are rich in energy and nutrients sources that can be recovered and reused in a circular bioeconomy perspective. Microalgae can effectively utilize wastewater nutrients for growth and biomass production. Integration of wastewater treatment and microalgal cultivation improves the environmental impacts of the currently used wastewater treatment methods. This review provides comprehensive information on the potential of using microalgae for the recovery of carbon, nitrogen, phosphorus and other micronutrients from wastewaters. Major factors influencing large scale microalgal wastewater treatment are discussed and future research perspectives are proposed to foster the future development in this area.
Paranasal sinusitis is widespread and can lead to orbital complications, blindness, and death. However, the correlation between ophthalmological findings and disease staging remains unclear. This ...study aimed to investigate the staging, acute ophthalmological manifestations, diagnosis, management, and outcomes of orbital complications of paranasal sinusitis during a 27-year period.
We retrospectively reviewed the medical records of all patients with orbital complications of paranasal sinusitis hospitalized at the National Cheng Kung University Hospital, a medical center in Taiwan during 1988-2015. Sex, age, symptoms, history, ophthalmological findings, laboratory and imaging findings, treatments, and outcomes were analyzed by staging.
Eighty-three patients aged 9 days to 80 years had stage I (preseptal cellulitis, n = 39 patients), II (postseptal orbital cellulitis, n = 8), III (subperiosteal abscess, n = 16), IV (orbital abscess, n = 8), or V (intracranial involvement, n = 12) complications. Peak incidences occurred in patients aged 0-19 and 60-69 years. Chronic sinusitis and diabetes mellitus were common preexisting diseases. Extraocular movement limitation and proptosis predicted postseptal (stage II or more) involvement. The likelihood of elevated intraocular pressure increased with stage. Reduced visual acuity and presence of relative afferent pupillary defect indicated consideration of magnetic resonance imaging to investigate possible intracranial extension. Ipsilateral maxillary (81.7%) and ethmoidal (75.6%) sinuses were the most common sources of infection, and the most frequently implicated pathogens were coagulase-negative Staphylococcus spp. (25.3%) and Staphylococcus aureus (20.5%). All patients received intravenous antimicrobial therapy (multi-drug therapy in 88.0%), and 55.4% underwent surgery, most commonly endoscopic sinus surgery. One (1.2%) diabetic man with stage V complications died of fungal sinusitis with intracranial invasion. Five (6.0%) patients, all stage V, lost vision despite intensive treatment. The average length of hospital stay was 13.8 days (range 2-72 days), and significantly longer stays were associated with stages II-V as compared to stage I.
Orbital infection originating from paranasal sinusitis can cause vision loss and death due to intracranial extension. Acute ophthalmological findings predict staging and prognosis. Cooperative consultation between ophthalmologists, otorhinolaryngologists, and neurologists is essential. Urgent diagnostic studies and aggressive antimicrobial therapy are indicated, and surgery should be considered.
Macroalgae (seaweeds) are abundant in functional polysaccharides known for their unique biochemical activities. In this study, the antioxidant, anti-lipogenic, and anti-inflammatory activities of the ...fucoidan extracted from brown seaweed Sargassum siliquosum were investigated by 1,1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging ability, lipid synthesis inhibition, and suppression of pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) production, respectively. To examine the effect of molecular mass on fucoidan's bioactivities above, the extracted fucoidan was subject to hydrogen peroxide-mediated partial hydrolysis to obtain lower molecular mass compounds within the range of 107.3–3.2 kDa. Results indicated that fucoidan's antioxidant activity increased with a corresponding decrease in molecular mass; the dosage for the half-maximal response (EC50) dropped from 2.58 to 1.82 mg/mL when the molecular mass decreased from 107.3 to 3.2 kDa. In addition, both the anti-lipogenesis and anti-inflammatory activities of fucoidan were significantly enhanced by 71.1% and 36.7%, respectively, when the molecular mass decreased to about 3 kDa. To further test the effect of sulfation on fucoidan's bioactivities, low molecular mass fucoidan was treated with SO3-DMF to increase the sulfate content. The results indicated that when sulfate content increased from 18.7% to 32.1%, EC50 of DPPH decreased from 1.82 mg/mL to 0.86 mg/mL and the anti-inflammatory activity also increased by 35.2%; however, the anti-lipogenesis activity decreased.
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•Degradation of purified Sargassum siliquosum fucoidan could upgrade functional activities.•Adding sulfate groups to low molecular mass fucoidan enhanced DPPH removal ability.•Adding sulfate groups to low molecular mass fucoidan enhanced the anti-inflammatory effect.•Higher sulfate content of low molecular mass fucoidan reduced lipogenesis in HepG2 cells.
Microalgae have the ability to mitigate CO
2 emission and produce oil with a high productivity, thereby having the potential for applications in producing the third-generation of biofuels. The key ...technologies for producing microalgal biofuels include identification of preferable culture conditions for high oil productivity, development of effective and economical microalgae cultivation systems, as well as separation and harvesting of microalgal biomass and oil. This review presents recent advances in microalgal cultivation, photobioreactor design, and harvesting technologies with a focus on microalgal oil (mainly triglycerides) production. The effects of different microalgal metabolisms (i.e., phototrophic, heterotrophic, mixotrophic, and photoheterotrophic growth), cultivation systems (emphasizing the effect of light sources), and biomass harvesting methods (chemical/physical methods) on microalgal biomass and oil production are compared and critically discussed. This review aims to provide useful information to help future development of efficient and commercially viable technology for microalgae-based biodiesel production.
► Components of microalgal biomass are suitable for biofuels production and biorefineries. ► Characterization and application of microalgae-based lipids, carbohydrates, pigments and proteins are ...elucidated. ► Critical comments were made on the role of microalgae in fermentation, food, and pharmaceutical industries.
The potential for biodiesel production from microalgal lipids and for CO2 mitigation due to photoautotrophic growth of microalgae have recently been recognized. Microalgae biomass also has other valuable components, including carbohydrates, long chain fatty acids, pigments and proteins. The microalgae-based carbohydrates consist mainly of cellulose and starch without lignin; thus they can be ready carbon source for the fermentation industry. Some microalgae can produce long chain fatty acids (such as DHA and EPA) as valuable health food supplements. In addition, microalgal pigments and proteins have considerable potential for many medical applications. This review article presents comprehensive information on the current state of these commercial applications, as well as the utilization and characteristics of the microalgal components, in addition to the key factors and challenges that should be addressed during the production of these materials, and thus provides a useful report that can aid the development of an efficient microalgae-based biorefinery process.
The problem of climate change arising mainly from CO₂ emission is currently a critical environmental issue. Biofixation using microalgae has recently become an attractive approach to CO₂ capture and ...recycling with additional benefits of downstream utilization and applications of the resulting microalgal biomass. This review summarizes the history and strategies of microalgal mitigation of CO₂ emissions, photobioreactor systems used to cultivate microalgae for CO₂ fixation, current microalgae harvesting methods, as well as applications of valuable by-products. It is of importance to select appropriate microalgal species to achieve an efficient and economically feasible CO₂-emission mitigation process. The desired microalgae species should have a high growth rate, high CO₂ fixation ability, low contamination risk, low operation cost, be easy to harvest and rich in valuable components in their biomass.
► Scenedesmus obliquus CNW-N is a good candidate for CO2 fixation and biofuels production. ► A light intensity of 420μmolm−2s−1 favors CO2 fixation and lipid/sugar production. ► Carbohydrate/lipid ...production was enhanced by nitrogen starvation strategies. ► Accumulation of lipid/carbohydrate can be adjusted by the nitrogen starvation time.
Engineering strategies were applied to improve the CO2 fixation rate and carbohydrate/lipid production of a Scenedesmus obliquus CNW-N isolate. The light intensity that promotes cell growth, carbohydrate/lipid productivity, and CO2 fixation efficiency was identified. Nitrogen starvation was also employed to trigger the accumulation of lipid and carbohydrate. The highest productivity of biomass, lipid, and carbohydrate was 840.57mgL−1d−1, 140.35mgL−1d−1. The highest lipid and carbohydrate content was 22.4% (5-day N-starvation) and 46.65% (1-day N-starvation), respectively. The optimal CO2 consumption rate was 1420.6mgL−1d−1. This performance is better than that reported in most other studies. Under nitrogen starvation, the microalgal lipid was mainly composed of C16/C18 fatty acid (around 90%), which is suitable for biodiesel synthesis. The carbohydrate present in the biomass was mainly glucose, accounting for 77–80% of total carbohydrates. This carbohydrate composition is also suitable for fermentative biofuels production (e.g., bioethanol and biobutanol).
Three indigenous microalgae strains (Scenedesmus subspicatus GY-16, Chlorella vulgaris FSP-E, and Anistrodesmus gracilis GY-09) were evaluated for their ability to accumulate carbohydrates to ...subsequently serve as feedstock for biohydrogen production. The results of photoautotrophic growth show that among the three strains examined, C. vulgaris FSP-E displayed the highest biomass productivity (825.6 mg/L/d) and carbohydrate productivity (365.8 mg/L/d). Mixotrophic growth of C. vulgaris FSP-E with the addition of 2.0 g/l of sodium acetate further increased the biomass and carbohydrate productivity to 1022.3 mg/L/d and 498.5 mg/L/d, respectively. Moreover, operating photobioreactor on semi-batch mode enhanced the stability for prolonged incubation of the carbohydrate-rich C. vulgaris FSP-E and the biomass and carbohydrate productivity obtained were 1063.3 and 384.8 mg/L/d, respectively. The biomass of C. vulgaris FSP-E was then used as feedstock for biohydrogen production via separate hydrolysis and fermentation processes. The acidic hydrolysate (hydrolyzed with 1% H2SO4) was fermented with Clostridium butyricum CGS5, giving a maximum H2 yield of 2.87 mmol H2/g biomass and a H2 production rate of 176.9 ml/h/l, which are higher than most reported values. The results obtained in this work indicate that carbohydrate-based microalgae feedstock shows good potential for biohydrogen production.
•Three microalgae strains were examined for the ability to accumulate carbohydrates.•Chlorella vulgaris FSP-E had the highest biomass and carbohydrate productivity.•Carbohydrate-rich C. vulgaris FSP-E was effectively hydrolyzed simply with 1% H2SO4.•The microalgae hydrolysate was converted to H2 with C. butyricum at high efficiency.•Obtained microalgae-based bioH2 production performance is better than literature.
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