User:Acwageman/sandbox

Article Evaluation

Reflection paragraph

Saponification

This article is relatively short, and I think it could be organized a lot better. The headings aren't super descriptive and some (Triglycerides and Oil paints) are more specific than others (Applications). The material within the article is definitely not addressed uniformly. The longest section of the article addresses saponification that occurs in oil paintings, which is an extremely specific instance of the general reaction, albeit a rather important and practical one. For this reason, I would suggest turning this section into its own article on saponification in oil paintings. This is an active field of scientific research and cultural interest, and removing this section from the Saponification article would allow for these topics to be expanded upon without overwhelming the more general article. In general, the citations appear to be from reliable sources. I think the article would benefit most from either expanding greatly on other examples or applications of saponification reactions or from creating new articles that go in depth about the applications and refocusing the original article on the chemistry and general reaction scheme.

Text I posted to the article's talk page

I think it may be beneficial to move the oil paint section to its own article. That way it would be possible to expand on the research being done in this specific area without overwhelming this general article.

Initial planning for my article

Droplet-based microfluidics

The article I'll be editing is the article on droplet-based microfluidics. Specifically, I'll be adding to the section on droplet manipulation. I'll be writing about droplet incubation, specifically delay lines. There is basically nothing about droplet incubation on the page yet, aside from a couple of very brief mentions of being able to incubate single cells in the cell culture section. I plan to introduce the need for incubation by discussing the use of droplets for performing chemical reactions and for incubating cells. I may talk about off-chip incubation methods if I find that it fits well and I have the space. I will focus my section on the development of delay lines and their capabilities.

Initial drafting of my article

Motivation for development of delay lines

• Need to incubate contents of droplets, whether they are living cells or reaction mixtures
• Desire for time-resolved droplet control, especially for chemical reactions

Design of delay lines

• Increase channel length to centimeters to meters
• Increase channel width and depth (to approximately double) to keep back pressure low

Modifications to delay line

• Reservoir
• Fabricated array/traps
• Constrictions
• Alter geometry for mixing

Add to an article

Sentences I added / edited

Oil paints are composed of pigment molecules suspended in an oil binding medium. Heavy metal salts are often used as pigment molecules, such as in lead white, red lead, and zinc white. If those heavy metal salts react with free fatty acids in the oil medium, metal soaps may form in a paint layer that can then migrate outward to the painting's surface.

Citation I added

"Pigment | Grove Art". doi:10.1093/gao/9781884446054.001.0001/oao-9781884446054-e-7000067586. Retrieved 2018-01-16.

Article I emailed for peer review

Droplet Manipulation

Delay lines

In order to make droplet-based microfluidics a viable technique for carrying out chemical reactions or working with living cells on the microscale, it is necessary to implement methods allowing for droplet incubation. Chemical reactions often need time to occur, and living cells similarly require time to grow, multiply, and carry out metabolic processes. Droplet incubation can be accomplished either on-chip or off-chip, depending on the parameters of the system. Off-chip incubation is useful for incubation times of a day or more or for incubation of millions of droplets at a time. On-chip incubation allows for integration of droplet manipulation and detection steps in a single device.

Droplets containing cells can be stored off-chip in PTFE tubing for up to several days while maintaining cell viability and allowing for droplets to be reinjected onto another device for analysis. Droplets can also be removed from the chip after formation and cell encapsulation and guided through a system of glass capillaries and tubing leading to a syringe. Droplets can be incubated in the syringe and then directly injected onto another chip for further manipulation or detection and analysis.

Delay lines are used to incubate droplets on-chip. After formation, droplets can be introduced into a serpentine channel with length of up to a meter or more. Increasing the depth and width of the delay line channel (as compared to channels used to form and transport droplets) allows for increased incubation time while minimizing channel back-pressure. Because of the larger channel size, droplets fill the delay line channel after formation, and incubation occurs in the time it takes for the droplets to traverse this channel. For systems where it is important to have a uniform distribution of total incubation time for all droplets, the delay line channel may contain regular constrictions and re-widenings. Varying the length of the delay line channel from tens of centimeters to one or more meters results in incubation times ranging from minutes to 12 or more hours. Cell viability has been demonstrated using on-chip delay lines for up to 12 hours, and droplet stability has been maintained for up to 3 days.

Revised article after peer review

Droplet manipulation

[should be increased to regular 'Heading' in article]

Droplet incubation

In order to make droplet-based microfluidics a viable technique for carrying out chemical reactions or working with living cells on the microscale, it is necessary to implement methods allowing for droplet incubation. Chemical reactions often need time to occur, and living cells similarly require time to grow, multiply, and carry out metabolic processes. Droplet incubation can be accomplished either within the device itself (on-chip) or externally (off-chip), depending on the parameters of the system. Off-chip incubation is useful for incubation times of a day or more or for incubation of millions of droplets at a time. On-chip incubation allows for integration of droplet manipulation and detection steps in a single device.

Off-chip incubation

Droplets containing cells can be stored off-chip in PTFE tubing for up to several days while maintaining cell viability and allowing for reinjection onto another device for analysis. Evaporation of aqueous and oil-based fluids has been reported with droplet storage in PTFE tubing, so for storage longer than several days, glass capillaries are also used. Finally, following formation in a microfluidic device, droplets may also be guided through a system of capillaries and tubing leading to a syringe. Droplets can be incubated in the syringe and then directly injected onto another chip for further manipulation or detection and analysis.

On-chip incubation

Delay lines are used to incubate droplets on-chip. After formation, droplets can be introduced into a serpentine channel with length of up to a meter or more. Increasing the depth and width of the delay line channel (as compared to channels used to form and transport droplets) enables longer incubation times while minimizing channel back pressure. Because of the larger channel size, droplets fill up the delay line channel and incubate in the time it takes the droplets to traverse this channel.

Delay lines were originally designed for incubating droplets containing chemical reaction mixtures and were capable of achieving delay times of up to one hour. These devices make use of delay line channels tens of centimeters in length. Increasing the total length of the delay line channels to one or more meters made incubation times of 12 or more hours possible. Delay lines have been shown to maintain droplet stability for up to 3 days, and cell viability has been demonstrated using on-chip delay lines for up to 12 hours. Prior to the development of delay lines, on-chip incubation was performed by directing droplets into large reservoirs (several millimeters in both length and width), which offers high storage capacity and lower complexity of device construction and operation if precise time control of droplets is not required.

If it is important to have a uniform distribution of incubation times for the droplets, the delay line channel may contain regularly-spaced constrictions. Droplets flowing through a channel of uniform diameter travel at different speeds based on their radial position; droplets closer to the center of the channel move faster than those near the edges. By narrowing the channel width to a fraction of its original size, droplets with higher velocities are forced to equilibrate with slower-moving droplets because the constriction allows fewer droplets to pass through at a time. Another manipulation to the geometry of the delay line channel involves introducing turns to the droplets' trajectory. This increases the extent to which any reagents contained within the droplets are mixed via chaotic advection. For systems requiring the incubation of 100 to 1000 droplets, traps can be fabricated in the delay line channel that store droplets separately from one another. This provides for finer control and monitoring of individual droplets.

Reflective Essay

1. I worked on the Droplet-based microfluidics article (linked above under "Initial planning for my article"). This article already existed, and has been edited previously by students in this course. It contains some good information, but some of the sections are very brief, and several important aspects of droplet-based microfluidics haven't been covered at all. I also think the article would benefit greatly from the inclusion of images, but I think it'd be pretty difficult to find images that would be useful and also allowed by Wikipedia.
2. I contributed to the "Droplet manipulation" section of the article. The only topics covered under this heading so far are "Reagent addition" and "Magnetic droplets." I will be adding a subsection on droplet incubation, including an overview of why incubation is necessary, a brief description of off-chip incubation methods, and a longer description of delay lines. The latter covers what delay lines are and how they work, their capabilities with regard to incubation time, and modifications and additions that can be made to delay lines based on different system parameters and needs.
3. The biggest edit I made as a result of my peer review feedback was to split my article into a subsection on off-chip incubation and one on delay lines. After receiving this suggestion, it became really clear to me that my section could only be improved by having more structure. I also made several edits to improve readability (like changing "allows for," which is a phrase I overuse, to the more concise "enables"). Finally, there were several places that my reviewers alerted me to where I was unclear about whether the delay lines could be used for chemical reactions or cell incubation, which I addressed in my final version. I disagreed with some of my peer reviewers' comments, especially about grammar.
4. This assignment was definitely valuable in reinforcing material that we learned in class, although I almost feel like the material presented in lecture was so thorough to begin with that I was basically drawing from that to write my article rather than going out to find new information. I already felt pretty comfortable with finding and reading literature, and I imagine this was true of most of the class just because we happened to be all or almost all grad students this quarter. It was helpful to exchange feedback with my peers, especially because that basically required me to read and think about articles that other students had been working on instead of just my own. In general, I think I could have used more content feedback rather than grammatical feedback, because I was really looking for ways to expand my article. Admittedly, I think I probably gave a lot of grammatical edits to those I peer reviewed, too, but maybe an emphasis on ways to improve the content and scope of the articles for peer reviewers would help. I think my article will probably be helpful to Wikipedia readers, though I bet this isn't one of the most popular articles on Wikipedia. Sometimes when I'm reading Wikipedia to get an overview of something I'm learning about in a class, I honestly find the material to be pretty technical and not all that helpful, but I definitely think that my contribution is easy to read and understand. Overall, it was pretty cool to write something that will actually go on Wikipedia and potentially be read by people all over the world, but at the same time I feel like I spent almost more time learning about Wikipedia's rules and formatting my article for Wikipedia than actually researching and writing my article. I think this is only going to be exacerbated by trying to consolidate several of my peers' articles into a Wikipedia-ready submission. I think the assignment would be improved by reducing the number of Wikipedia trainings required and eliminating some of the tiny assignments like reviewing an article, adding to an article, initial planning, initial drafting, etc. Finally, I don't think it was made clear anywhere that 15 references were required until less than a week before the article was due (the only length guideline I can find is that it should be approximately 3 paragraphs), so I essentially doubled the length of my article in the last couple of days before it was due. Clarifying this earlier would have been very beneficial!