Plasma Chemistry, Laboratory

2021 ◽  
pp. 1-1
Author(s):  
Nathalie Carrasco
Keyword(s):  
Plasma Chemistry ◽  
Chemistry Laboratory

Material Structure of Microcrystalline Silicon Deposited with an Expanding Thermal Plasma

2003 ◽  
Vol 762 ◽  
Author(s):  
C. Smit ◽  
D.L. Williamson ◽  
M.C.M. van de Sanden ◽  
R.A.C.M.M. van Swaaij
Keyword(s):  
Thermal Plasma ◽  
Hydrogen Plasma ◽  
Plasma Chemistry ◽  
Plasma Source ◽  
Growth Direction ◽  
Interaction Time ◽  
Material Structure ◽  
Average Particle ◽  
Microcrystalline Silicon ◽  
X Ray

AbstractExpanding thermal plasma CVD (ETP CVD) has been used to deposit thin microcrystalline silicon films. In this study we varied the position at which the silane is injected in the expanding hydrogen plasma: relatively far from the substrate and close to the plasma source, giving a long interaction time of the plasma with the silane, and close to the substrate, resulting in a short interaction time. The material structure is studied extensively. The crystalline fractions as obtained from Raman spectroscopy as well as from X-ray diffraction (XRD) vary from 0 to 67%. The average particle sizes vary from 6 to 17 nm as estimated from the (111) XRD peak using the Scherrer formula. Small angle X-ray scattering (SAXS) and flotation density measurements indicate void volume fractions of about 4 to 6%. When the samples are tilted the SAXS signal is lower than for the untilted case, indicating elongated objects parallel to the growth direction in the films. We show that the material properties are influenced by the position of silane injection in the reactor, indicating a change in the plasma chemistry.

Integrating Disciplines in a Plant Chemistry Laboratory Module to Enhance Interdisciplinary and Scientific Thinking in Undergraduate Students

2019 ◽  
Author(s):  
Lucas Busta ◽  
Sabrina E. Russo
Keyword(s):  
Critical Thinking ◽  
Medicinal Plant ◽  
Systems Thinking ◽  
Undergraduate Students ◽  
Core Competencies ◽  
Chemistry Laboratory ◽  
Scientific Thinking ◽  
Written Communication ◽  
Plant Chemistry ◽  
Hands On

Here, we describe a hands-on medicinal plant chemistry laboratory module (Phytochemical Laboratory Activities for iNtegrative Thinking and Enhanced Competencies; PLANTEC) for undergraduates that targets the development of core competencies in (i) critical thinking and analysis of text and data, (ii) interdisciplinary and systems thinking, (iii) oral and written communication of science, and (iv) teamwork and collaboration.<br>

Developing and Implementing a Specifications Grading System in an Organic Chemistry Laboratory Course

2020 ◽  
Author(s):  
William J. Howitz ◽  
Kate J. McKnelly ◽  
Renee Link
Keyword(s):  
Organic Chemistry ◽  
Chemistry Laboratory ◽  
Grading System ◽  
Traditional Grading ◽  
Final Grade ◽  
Laboratory Courses ◽  
Lower Division ◽  
Collaborative Learning Environment ◽  
Organic Chemistry Laboratory ◽  
Grade Uncertainty

<p>Large, multi-section laboratory courses are particularly challenging when managing grading with as many as 35 teaching assistants (TAs). Traditional grading systems using point-based rubrics lead to significant variations in how individual TAs grade, which necessitates the use of curving across laboratory sections. Final grade uncertainty perpetuates student anxieties and disincentivizes a collaborative learning environment, so we adopted an alternative grading system, called specifications grading. In this system each student knows exactly what level of proficiency they must demonstrate to earn their desired course grade. Higher grades require demonstrating mastery of skills and content at defined higher levels. Each students’ grade is solely dependent on the work they produce rather than the performance of other students. We piloted specifications grading in the smaller, third quarter course of the lower division organic chemistry laboratory series held during a summer term. Open-ended questions were chosen to gather student and TA perceptions of the new grading system. TAs felt that the new grading system reduced the weekly grading time because it was less ambiguous. Responses from students about the nature of the grading system were mixed. Their perceptions indicate that initial buy-in and multiple reminders about the bigger picture of the grading system will be essential to the success of this grading system on a larger scale.</p>

Assessment of Irrigation Quality of Disposal Water of Ashuganj-Polash Agro-Irrigation Project, Brahmanbaria Bangladesh

2017 ◽  
Vol 4 (04) ◽  
Author(s):  
ABDUR RAZZAK ◽  
PARSA SANJANA ◽  
BELAL HOSSAIN ◽  
DEBJIT ROY ◽  
BIDHAN CHANDRA NATH
Keyword(s):  
Soil Sample ◽  
Water Samples ◽  
Crop Production ◽  
Soil Samples ◽  
Chemistry Laboratory ◽  
Total Hardness ◽  
Sodium Absorption ◽  
Irrigation Project ◽  
Crop Field ◽  
Initial Soil

The study was conducted at Ashuganj-Polash agro-irrigation project (APAIP), Brahmanbaria,aim to determine the chemical properties of power plant disposal water and to assess its suitability for irrigation. Initial soil samples (before irrigating crop field) and final soil samples (after crop harvesting) were collected. During irrigation ten water samples (six from crop field and four from irrigation canals) were collected for analysis. All soil samples were analyzed in Humboldt soil testing laboratory and water samples in bio-chemistry laboratory of Bangladesh Agricultural University and compared to FAO irrigation standard. Results show thatthe sodium absorption ratio (SAR) (0.53 to 0.88), residual sodium bi-carbonate (0.8 to 1.3meq L-1), Kelly’s ratio (0.31 to 0.6) and total hardness (85 to 150) found in normal range and largely suitable for irrigation. Soluble sodium percentage values found in satisfactory (20.26 to 41.1) level and magnesium absorption (57.1 to 76.4) found unsuitable for irrigation. Statistically similar value of pH, EC, total nitrogen, organic carbon, calcium, magnesium and phosphorus in initial and final soil sample were observed. But potassium and sulfur value reduced in final soil sample from initial soil. The water samples fall within the permissible limit and found suitable for crop production

Students’ meaningful learning experiences from participating in organic chemistry writing-to-learn activities

2021 ◽  
Author(s):  
Trisha Gupte ◽  
Field M. Watts ◽  
Jennifer A. Schmidt-McCormack ◽  
Ina Zaimi ◽  
Anne Ruggles Gere ◽  
...  
Keyword(s):  
Organic Chemistry ◽  
Learning Strategies ◽  
Learning Experience ◽  
Learning Experiences ◽  
Meaningful Learning ◽  
Writing To Learn ◽  
Chemistry Laboratory ◽  
Primary Data ◽  
Survey Analysis ◽  
Problem Solving Skills

Teaching organic chemistry requires supporting learning strategies that meaningfully engage students with the challenging concepts and advanced problem-solving skills needed to be successful. Such meaningful learning experiences should encourage students to actively choose to incorporate new concepts into their existing knowledge frameworks by appealing to the cognitive, affective, and psychomotor domains of learning. This study provides a qualitative analysis of students’ meaningful learning experiences after completing three Writing-to-Learn (WTL) assignments in an organic chemistry laboratory course. The assignments were designed to appeal to the three domains necessary for a meaningful learning experience, and this research seeks to understand if and how the WTL assignments promoted students’ meaningful learning. The primary data collected were the students’ responses to open-ended feedback surveys conducted after each assignment. These responses were qualitatively analyzed to identify themes across students’ experiences about their meaningful learning. The feedback survey analysis was triangulated with interviews conducted after each assignment. The results identify how the assignments connected to students’ existing knowledge from other courses and indicate that assignment components such as authentic contexts, clear expectations, and peer review supported students’ meaningful learning experiences. These results inform how assignment design can influence students’ learning experiences and suggest implications for how to support students’ meaningful learning of organic chemistry through writing.

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