DIFFERENCES IN CONTEXT: REVEALING EXPERT-NOVICE GRAPH KNOWLEDGE IN BIOLOGY

Graphs are typically defined as visual representations that depict and sometimes summarize quantitative data. Visual representation of quantitative data is broadly used in scientific textbooks, papers, and lectures as well as popular media seen in everyday life. Thus, understanding graphs and data became an essential skill for all students to master. However, correctly and fully using graphs requires a person to have multiple competencies (diSessa & Sherin, 2000). For an instance, during graph construction, variables need to be identified and characterized, data are screened and often reduced, and a graph type needs to be chosen that is appropriate for the data. Student have difficulties interpreting and constructing scientific graphs (Beichner, 1994; Mevarech, & Karamarsky, 1997; Shaw, Padilla, & Mckenzie, 1983; Speth et al., 2010); in spite of using some of the documented difficulties to improve instruction, difficulties persist for undergraduate science students (Speth et al., 2010; McFarland, 2010). We aim to compare the differences in graph knowledge among undergraduate biology students, graduate biology students, and biology professors. Using the results, we hope to better understand and define the role that graph knowledge plays in students’ ability to choose and create appropriate graphs from data. This will be beneficial to instructors who teach analytical and graphical skills at school and to educators who design the curriculum with a purpose of effective teaching and learning

A novel, simple near-infrared thoracoscopic technique by a particular route for locating lung nodules

BackgroundThe localization of pulmonary nodules prior to thoracoscopic surgery remains challenging for thoracic surgeons, especially for those nodules that are not visible or palpable on the lung surface. Our study is a simple and effective minimally invasive method using indocyanine green through a special pathway to locate pulmonary nodules and fluorescence thoracoscopic surgery.MethodsThoracoscopic surgery was performed for 18 undiagnosed peripheral non-solid nodules no larger than 2 cm after location. After 0.3 mg/kg indocyanine green was injected through the peripheral vein, the puncture needle was pulled out after it reached approximately 1 cm of the pulmonary parenchyma near the nodules. This was followed by transfer to the operating room. The nodule was initially localized by using a near-infrared thoracoscope to visualize indocyanine green fluorescence. Then, thoracoscopic resection was performed.ResultsEighteen patients received this special and simple localization method, and underwent near-infrared, image-guided, video-assisted thoracoscopic surgery resection. Median computed tomography (CT) tumor size was 1.2 cm. Median depth from the pleural surface is 1.6 cm (range, 0.1–4.6 cm). The median time of CT-guided intervention was 12 min. The duration of thoracoscopic surgery was 67 min. Indocyanine green fluorescence was clearly identified in 17 of 18 patients (94.4%). The surgical margins were all negative on final pathology. The final diagnoses included 17 primary lung cancers, and 1 benign lung tumor.ConclusionsCT-guided single puncture of indocyanine green after peripheral intravenous injection is a simple, effective, and safe method to locate the nodule. This offers surgeons the ease of localization through direct indocyanine green fluorescence imaging, and it can be used as an effective alternative to other placement methods of locating pulmonary nodules

Phosphorus Recovery from Synthetic Municipal Wastewater through Lignin-induced Struvite Precipitation

Phosphorus recovery from wastewaters is essential to resolve the problems of the fast depletion of phosphate rocks due to the increasing demand for phosphorus fertilizer, and eutrophication due to excessive phosphorus discharging from wastewater. In this study, the feasibility of adding alkaline lignin as seed materials to promote phosphorus recovery through fertilizer struvite (NH4MgPO4·6H2O) crystallization from synthetic municipal wastewater was evaluated via batch experiments. Influencing factors tested included lignin dosage, Mg/P molar ratio, and pH. Lignin addition enhanced phosphorus recovery by 44.6% at a relatively low pH of 7.9 with Mg/P molar ratio of 1.5 and lignin dosage of 6 g/L, resulting in the reduced potential of co-precipitation and the cost-saving on alkali addition. As pH increases, however, this effect becomes less noticeable because of the higher solubility of lignin in wastewater. The characterizations by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and zeta potential analysis, combined with precipitation modeling by a thermodynamic model software (Visual MINTEQ) were done to understand the process. Struvite-lignin clusters were identified, likely due to the in-situ-pH-favorable nucleation sites on lignin enhanced struvite crystallization. As for the application in wastewater with different characteristics, the effect of lignin on enhancing phosphorus recovery efficiency is still significant under different PO4-P and NH4-N concentrations, indicating the effect-stability and availability of lignin in promoting struvite crystallization. As for the total suspended solids (TSS), the results show that the effect of TSS on phosphorus recovery efficiency is not significant (p > 0.05). Moreover, lignin is more efficient in increasing phosphorus recovery under relatively lower alkalinity while could reduce the co-precipitates potential under higher alkalinity. Overall, this study provides a new possibility of the use of lignin from paper mill black liquor as seed material to enhance phosphorus recovery from wastewater, making the struvite production more efficient and cost-effective

Research on AUV underwater landing strategy based on variable buoyancy system

[Objectives] The underwater landing of an Autonomous Underwater Vehicle(AUV)is a way to achieve underwater long-term latency and fixed-point observation which is conductive to the better control of changes in the marine environment.[Methods] This paper mainly introduces the fundamental structure and main functions of an AUV which is based on the oil sac type variable buoyancy system. Two kinds of underwater landing strategies are established:controlled buoyancy vertical dive landing and sailing dive and controlled buoyancy vertical landing. The target point deviation,energy consumption and AUV take-off from the bottom are analyzed,and the actual underwater landing experimental verification is carried out in a lake.[Results] The experimental results show that the AUV is able to steadily land underwater and take off from the bottom safely with this variable buoyancy system. The control strategy of sailing dive and controlled buoyancy vertical landing can save more energy,and the landing point is more accurate than with the strategy of controlled buoyancy vertical diving.[Conclusions] As such,the control strategy of sailing dive and controlled buoyancy vertical landing is more in line with the demands of future practical application

Phosphorus recovery from synthetic biosolid digestion supernatant through lignin-induced struvite precipitation

Phosphorus recovery from wastewater is essential to resolve the problems of the fast depletion of phosphate rocks due to the increasing demand of phosphorus fertilizer and eutrophication caused by excessive phosphorus discharging from wastewater. In this study, the feasibility of adding lignin as seed materials to promote phosphorus recovery through struvite (NH4MgPO4·6H2O) crystallization from synthetic biosolid digestion supernatant was evaluated via batch experiments. Influencing factors including lignin dosage, Mg/P molar ratio, and pH were tested. Lignin addition enhanced phosphorus recovery by 44.6% at a relatively low pH of 7.9 with Mg/P molar ratio of 1.5 and lignin dosage of 6 g/L, improved the quality of recovered struvite crystals by reducing the potential of co-precipitation. The phosphorus recovery improvement became less noticeable and the extent of reducing the potential of co-precipitation became more evident as pH increases from 7.9 to 9.5. The characterizations by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and zeta potential analysis, combined with precipitation modeling by a thermodynamic model software (Visual MINTEQ) were done to understand the process. Struvite-lignin clusters were identified, which likely provide nucleation sites on lignin to enhance struvite crystallization. It can be concluded that the inclusion of Kraft lignin as a seeding material might be a sustainable strategy to enhance struvite formation, improve phosphorus recovery, and yield high-quality struvite.</p