Absorption of carbon dioxide in a bubble plate tower

Gas absorption, one of the chief operations of chemical engineering, has occupied investigators for a long time. Results of many experiments on the general subject of gas absorption has been published. However, relatively few data have appeared in the literature on the use of bubble cap towers for gas absorption although they constitute one of the three major classifications of absorption equipment. Bubble cap towers are used extensively in the petroleum industry. More performance data would increase the versatility of existing equipment --Introduction, page 1

Relationships between foliar applied micronutrients, soil and tissue tests, and grain yield in soybean

There has been little research with foliar application of micronutrients for soybean [Glycine max (L.) Merr.] in the Corn Belt, and results have been inconsistent. This study\u27s objectives were to (1) evaluate the soybean grain yield response to foliar application of B, Cu, Mn, and Zn; and (2) study relationships between soil and plant-tissue test results for these micronutrients. Forty-two field trials were conducted in Iowa during 2012 and 2013 that involved 23 soil series. Six treatments replicated four times were a control, each nutrient applied separately, and their mixture sprayed twice (at the V6 and R2/R3 growth stages) (Fehr et al., 1971). Total applied rates of B, Cu, Mn, and Zn were 180, 87, 370, and 555 g ha-1, respectively. Micronutrient concentrations in the soil were analyzed in dried or undried samples. Results for the common dry sample handling procedure for B (15-cm depth, hot-water method) were 0.23 to 1.66 mg kg-1; for Cu, Mn, and Zn were 1.6 to 4.2, 31.5 to 128, and 1.2 to 11 mg kg-1 by Mehlich-3 (M3), and 0.28 to 1.83, 3.8 to 42.3, and 0.48 to 15.1 mg kg-1 by the diethylenetriamine-pentaacetic acid (DTPA) method. Total B, Cu, Mn, and Zn in plants at the V5-V6 stage were 24.3 to 41.5, 5.3 to 15.0, 29 to 113, and 24.5 to 47.8 mg kg-1; and in leaves at the R2-R3 stage were 27 to 62.3, 3.8 to 11, 26 to 88, and 17.8 to 47.3 mg kg-1. Fertilization did not increase grain yield at any site (P ≤ 0.05), the mixture decreased average yield across sites, and with the exception of Mn often increased grain concentration. Except for a good curvilinear relationship between soil Zn by Mehlich-3 and DTPA methods (R2 0.94), all other relationships among micronutrients in soil, plants, and leaves were poorer and often not significant. No yield response-based soil or plant-tissue concentrations could be identified given the lack of yield responses, but results suggest that the lowest observed soil and tissue test concentrations would be adequate for soybean in conditions similar to those in this study

Elementary Preservice Teachers’ Perceptions of Modeling as a Tool for Instruction

As the standards movement continues to gain momentum in U.S. schools, preservice and in-service teachers need greater knowledge in mathematical modeling to engage PK-12 students in such practices. This case-based research study investigated the perceptions and understandings of modeling for 76 entry-level, preservice elementary teachers enrolled in a mathematics methods course at a mid-Atlantic university. Participants were prompted to define modeling and its application to classroom instruction through open-response questions administered in an online survey. A case-based, phenomenological method was used to code and analyze responses. Most preservice teachers expressed a very limited definition or understanding of modeling or how models are used to promote conceptual understanding of problems, systems, or phenomena in mathematics. The nature of the misconceptions and limits in understanding inform ways that higher education might approach the instruction of modeling in mathematics methods courses to develop such knowledge in future elementary teachers

STEM in General Education: Does Mathematics Competence Influence Course Selection

Many students enroll in college programs to prepare for their future careers. All are required to complete general studies courses. At one university, technology and STEM courses fulfill a part of the natural science and technology general education requirements. This study uses a survey design to explore why 332 students chose to enroll in a STEM technology course. Results found most enroll because their advisor suggests the course, it meets a general education major requirement, and the course is offered at a convenient time. Fewer enroll in the course because they would like to find out more about STEM fields, be exposed to potential careers, or because of the implicit need to study STEM subjects. Student mathematics skills were analyzed to determine if these skills influenced their choice for selecting this technology STEM course

Give Me a Formula Not the Concept! Student Preference to Mathematical Problem Solving

Purpose of Study: The purpose of this study was to assess student preference for procedural (formula-driven) versus conceptual (concept-driven) approaches to solve mathematical problems. Additionally, we evaluated differences in preferences among students who performed above average and those who performed at or below average on simple arithmetic problems. Methods/Design and Sample: We used a single-factor (Instructional Approach: conceptual vs. procedural) between-subjects experiment. Instructional approach was manipulated using short embedded instructional videos. Students evaluated each approach on a five-point scale. Results: We found that students (above-average and average/below-average) preferred the procedural approach to the conceptual approach. Interestingly, however, although students preferred the procedural approach when first introduced to it, above-average students evaluated the conceptual approach more positively if they were unable to solve a problem correctly and were presented with additional conceptual instruction. On the other hand, there was no change in the evaluation of the procedural approach. Value to Marketing Educators: The findings of this study indicate that students develop mathematical knowledge and understanding differently. Faculty who teach courses with a high degree of mathematics concepts should work to provide multiple experiences that include both procedural and conceptual techniques to develop a holistic understanding of mathematics

Preservice Secondary Mathematics Teachers’ Reflections in Using Excelets as a Tool for Modeling

With widespread adoption of technology for all into schools across the U.S., teachers need to be prepared to integrate these tools into classroom instruction. For mathematics, modeling problems with technology provides a key opportunity for students to experience the active nature of such tools in making sense of mathematics concepts. In order to gain insight into incorporating these tools into modeling tasks, preservice teachers need exposure to them as along with reflection on their use. This case study of 12 preservice secondary mathematics teachers enrolled in a mathematics methods course focused on a modeling task that was presented in an Excelet. Participants went through the Excelet and then reflected on the experience they had in interacting with it. Data included a video-recording of participants thinking-aloud while working through the Excelet and a survey consisting of 10 Likert-type and 5 open-ended questions where they reflected on their experience. Findings indicate that by reflecting on the experience related to using this tool, preservice teachers gained insight into challenges in integrating technology within content instruction. Participants fell into categories of strong or weak reflective individuals crossed with strong or weak users of technology. Findings of this study provide more evidence that teacher preparation programs still have work to do in preparing mathematics teachers to integrate technological tools into classroom instruction

A Case Study of a STEM Teacher’s Development of TPACK in a Teacher Preparation Program

This case study involved researching pre-service secondary STEM teachers’ development of TPACK by use of modeling & simulation applications. The main research question focused on how do self-reported TPACK measures align with demonstrated TPACK knowledge and skills. The study design was qualitative and included five secondary STEM pre-service teachers who were completing their program of study and teaching lessons in the field with secondary students. This particular brief paper reports on one of the pre-service STEM teachers in this study. Coding and analysis were carried out to search for characteristics of tasks that support development of TPACK in future teachers. Findings from this one case identified somewhat high marks on the TPACK self-scores but weaker identification of features of modeling and simulation (M&S) applications integrated into instructional use. The challenge for teacher education programs is to search for ways to better measure and support TPACK development in future teachers

Hiponatremia como marcador asociado a apendicitis complicada en pacientes del hospital Belén de Trujillo

Objetivo: Analizar si la hiponatremia es un marcador de riesgo de apendicitis complicada en pacientes del “Hospital Belén” de Trujillo durante el 2024. Material y métodos: Se llevó a cabo un estudio de cohortes, analítico en el que se incluyeron a 88 pacientes con diagnóstico de apendicitis aguda, según criterios de selección los cuales se dividieron en función de la presencia o no de hiponatremia, se calculó el chi cuadrado y el estadígrafo riesgo relativo. Resultados: El promedio de edad, tiempo de enfermedad, recuento de leucocitos, proteína c reactiva y la frecuencia de comorbilidades fue significativamente mayor en el grupo con hiponatremia (p<0.05), la incidencia de apendicitis complicada en los pacientes con hiponatremia fue de 77%, la incidencia de apendicitis complicada en los pacientes sin hiponatremia fue de 24%, la hiponatremia es marcador asociado a apendicitis complicada presentando un riesgo relativo de 3.2, el cual fue estadísticamente significativo (p<.0.05), en el análisis multivariado a través de regresión logística se logra identificar a la edad avanzada, tiempo de enfermedad mayor a 48 horas, recuento de leucocitos mayor de 12 x 109 , proteína C reactiva mayor de 50 mg/L e hiponatremia como factores de riesgo para apendicitis complicada Conclusión: la hiponatremia es un marcador de riesgo asociado a apendicitis complicada en pacientes del Hospital Belén de Trujillo durante junio y julio del 2024Objective: To analyze whether hyponatremia is a risk marker for complicated appendicitis in patients at the “Belén Hospital” in Trujillo during 2024. Material and methods: An analytical cohort study was carried out in which 88 patients with a diagnosis of acute appendicitis were included, according to selection criteria which were divided according to the presence or not of hyponatremia, the chi was calculated. square and the relative risk statistician. Results: The average age, duration of illness, leukocytes count, c-reactive protein and the frequency of comorbidities was significantly higher in the group with hyponatremia (p<0.05), the incidence of complicated appendicitis in patients with hyponatremia was 77%. The incidence of complicated appendicitis in patients without hyponatremia was 24%, hyponatremia is a marker associated with complicated appendicitis with a relative risk of 3.2 which was significant (p<.0.05), in the multivariate analysis through logistic regression. identify advanced age, duration of illness, leukocyte count greater than 12 x 109 , C-reactive protein greater than 50 mg/L and hyponatremia as risk factors for complicated appendicitis. Conclusion: hyponatremia is a risk marker associated with complicated appendicitis in patients at the Belén Hospital in Trujillo during June and July 2024Tesi