I finally finished my report!!! it is a really great and rather difficult experience to put all my thoughts and results down, as there are so much to write about!! but at last, it is done and I have said all that I want to.
Here are the links to the online files mentioned in my Appendix:
RAW DATA: https://spreadsheets.google.com/spreadsheet/ccc?key=0AiMAlvdzOfXFdEYyQ1doTmctZzJkaFV2aHU3LW5xUVE&hl=en_US#gid=0
Secondary data: https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0ByMAlvdzOfXFYzU0NGI5YjItYWE2OC00ZTcwLWFkNDUtYmIwZTI5N2MzMmEw&hl=en_US
Tertiary data: https://spreadsheets0.google.com/spreadsheet/ccc?key=0AiMAlvdzOfXFdEM1UWY0Rm1paXNLZ1RweS01SU1uYmc&hl=en_US
Photographs: https://picasaweb.google.com/108870368937199680879/SIPDataPhotosUploaded
To the dear teachers marking this blog and the report: I know I've put up links to my data in the previous posts, but these are the refined ones, so they would be slightly different and more organised.
My blog has been a faithful documentation of the thought processes in planning the experiment, and notes taken to refine the report, etc etc. Thank you blog!
Monday, July 25, 2011
Thursday, July 14, 2011
Notes about my experiment and report
We went through the rubrics today. Things to note:
1. Present representative photographs in appendix, and add a link in the hardcopy to the online scrapbook to see full details of photos.
2. MUST paraphrase the lit review presented in the report. Would there be a section in template to include lit review?
3. Refer to lit review in the design of the experiment
4. For results, use 2 decimal places of accuracy whenever unsure. Follow strictly the calculation of levels of precision as learnt in physics.
5. Methodology MUST be reproducible - ask friend to try out based on given instructions.
6. Point out control variables that cannot be controlled.
7. Remember to vary ONLY ONE variable.
8. Data collection: is all the data collected necessary? Are the data collected enough for a good graph/analysis?
9. Presentation of data - in tables, with appropriate and SPECIFIC units and precision.
10. plot a graph for data analysis, in my case the rate of bacteria growth as graphs.
11. Use line graphs for rates and bar graphs for numbers.
12. refer back to literature review and observations in conclusion.
13. Limitations - things that you really cannot control about the experiment.
14. Extension - VERY IMPORTANT. further questions from your experiment. Crucial in a scientific investigation.
15. Provide plenty of evidence - hard data and photos - in the blog.
16. List out materials specifically.
17. Reflect on how to make the experiment better with more time/how to make it bigger.
1. Present representative photographs in appendix, and add a link in the hardcopy to the online scrapbook to see full details of photos.
2. MUST paraphrase the lit review presented in the report. Would there be a section in template to include lit review?
3. Refer to lit review in the design of the experiment
4. For results, use 2 decimal places of accuracy whenever unsure. Follow strictly the calculation of levels of precision as learnt in physics.
5. Methodology MUST be reproducible - ask friend to try out based on given instructions.
6. Point out control variables that cannot be controlled.
7. Remember to vary ONLY ONE variable.
8. Data collection: is all the data collected necessary? Are the data collected enough for a good graph/analysis?
9. Presentation of data - in tables, with appropriate and SPECIFIC units and precision.
10. plot a graph for data analysis, in my case the rate of bacteria growth as graphs.
11. Use line graphs for rates and bar graphs for numbers.
12. refer back to literature review and observations in conclusion.
13. Limitations - things that you really cannot control about the experiment.
14. Extension - VERY IMPORTANT. further questions from your experiment. Crucial in a scientific investigation.
15. Provide plenty of evidence - hard data and photos - in the blog.
16. List out materials specifically.
17. Reflect on how to make the experiment better with more time/how to make it bigger.
Friday, July 8, 2011
Review and Revise
After meeting Ms Tan, I need to do another batch of bacteria culture as I did not have negative control (an agar plate that has absolutely nothing done to it, to see the sterility of the agar plates), so in this new batch there will be a 7th plate, the negative control. I also need another batch to consolidate the results I have which are right now rather messy. If i have another set of results, I can analyse it more and perhaps identify the outliers more easily.
Another matter I am considering is the method of presenting my data. After all, I really have a lot of data. Right now I'm presenting in a table and maybe graphs the average amount of each type of bacteria on agar inoculated by each agent ON THE 3RD DAY, and on the 3rd day only. I have not yet decided whether to use the data of Days 1 and 2 anywhere. I think I need to decide because if not, I can save work and time by not counting the bacteria on Days 1 and 2 for my 4th batch.
I'm thinking to not waste any data, and present data about the rate with which DIFFERENT TYPES OF BACTERIA appear on plates inoculated with DIFFERENT AGENTS. to this, i can plot a combined graph of each type of bacteria, x-axis the number of days, y-axis the amount of bacteria, different lines representing different agents. Or I can plot combined graphs of each type of agent, with the same axes, the different lines representing the different types of bacteria. It all seems very very complicated.
So should I present the rate at which bacteria appear? It promises to be interesting, but is it relevant to my research question which is about the amount of bacteria removed? Does the rate at which bacteria colonies grow have any significance on the amount of bacteria inoculated onto the plate?
Or - another idea - maybe i can just use the data from Day 1, immediately after inoculation and on 3rd day.
Ms Tan also advise me to:
1, use pi to calculate area
2, use imageJ?
3, think about whether using different fingers affect the amount of bacteria
4, THE OPAQUE WHITE 'MOULD' IS ACTUALLY BACTERIA.
5, use the great photos i have so painstakingly taken!! yay, should i attached ALL of them as appendix?
By the way, is there a limit for appendix pages?
Another matter I am considering is the method of presenting my data. After all, I really have a lot of data. Right now I'm presenting in a table and maybe graphs the average amount of each type of bacteria on agar inoculated by each agent ON THE 3RD DAY, and on the 3rd day only. I have not yet decided whether to use the data of Days 1 and 2 anywhere. I think I need to decide because if not, I can save work and time by not counting the bacteria on Days 1 and 2 for my 4th batch.
I'm thinking to not waste any data, and present data about the rate with which DIFFERENT TYPES OF BACTERIA appear on plates inoculated with DIFFERENT AGENTS. to this, i can plot a combined graph of each type of bacteria, x-axis the number of days, y-axis the amount of bacteria, different lines representing different agents. Or I can plot combined graphs of each type of agent, with the same axes, the different lines representing the different types of bacteria. It all seems very very complicated.
So should I present the rate at which bacteria appear? It promises to be interesting, but is it relevant to my research question which is about the amount of bacteria removed? Does the rate at which bacteria colonies grow have any significance on the amount of bacteria inoculated onto the plate?
Or - another idea - maybe i can just use the data from Day 1, immediately after inoculation and on 3rd day.
Ms Tan also advise me to:
1, use pi to calculate area
2, use imageJ?
3, think about whether using different fingers affect the amount of bacteria
4, THE OPAQUE WHITE 'MOULD' IS ACTUALLY BACTERIA.
5, use the great photos i have so painstakingly taken!! yay, should i attached ALL of them as appendix?
By the way, is there a limit for appendix pages?
Friday, June 24, 2011
Results of my Experiment
I haven't posted in quite a while, because I was organizing all the data and stuff -- there is really quite a lot of data, and I organized them raw data then into groups, for better analysis.
I grouped the bacteria by, as I said, size and colour, but now I encounter quite some difficulty. The first of these is whether I should include analysis of the amount of mould in my report. I recorded the growth of mould in my data because it is very interesting, but it does not really fit my research question which is about bacteria. I think I can change my research to be about 'microbes' but antibacterial hand soap only claims to kill bacteria, so including mould in my research is rather a moot point.
Another difficulty is the fact that the pH of lime juice and lemon juice is the same - is it because they both contain citric acid? I think it is so, But now, what would be the chemistry aspect of my experiment? I think I will have to analyse the chemical components of the agents and find out what exactly kills or removes bacteria in them -- especially in limes and lemons. If it's really citric acid like I think, then this can be a chemical aspect of the experiment as well. (comparing the chemical properties of substances in removing bacteria).
And finally, I have no idea if we're supposed to hand in a draft of the report upon returning to school?
Here I am uploading links to the raw and more organized data.
ORGANIZED DATA: https://docs.google.com/document/d/1ZnpbuhF-Avogif4IaRSYlt47SR_Yf7IYIZqX4irqQRw/edit?hl=en_US
AND FINALISED DATA OFOR 3RD OBSERVATION FOR ALL BATCHES:
Thursday, June 2, 2011
Experimentation
Have done Day 1 and Day 2 of the experiment. A few corrections to the procedure:
1, used masking tape to seal up plates.
2, did not use stopwatch.
anyway, the results of 1st observation is rather unexpected: a lot of bacteria grew in lemon juice and distilled water, even more than control, while antibacterial soap seem to be nurturing mould.
I'm also having difficulty counting the bacterial colonies. Shall attempt ImageJ again, i took photos of the plates and I have to admit counting them is hard. I'm not sure if I haven't double-counted. And though i classified them into groups based on their sizes, some of them seem to be in between two groups, and some are merging into one (round shape or strip-shape) so it's really hard to count.
That's all for now.
1, used masking tape to seal up plates.
2, did not use stopwatch.
anyway, the results of 1st observation is rather unexpected: a lot of bacteria grew in lemon juice and distilled water, even more than control, while antibacterial soap seem to be nurturing mould.
I'm also having difficulty counting the bacterial colonies. Shall attempt ImageJ again, i took photos of the plates and I have to admit counting them is hard. I'm not sure if I haven't double-counted. And though i classified them into groups based on their sizes, some of them seem to be in between two groups, and some are merging into one (round shape or strip-shape) so it's really hard to count.
That's all for now.
Sunday, May 29, 2011
Final Experiment Procedure
After the many changes my experimental plan has gone through, I come up with this final procedure.
Materials and Apparatus:
18 prepared agar petri dishes
20 ml of pure lime juice
20 ml of pure lemon juiceDistilled water
20 ml of normal hand soap (brand: )
20 ml of antibacterial hand soap that claims to kill 99.9% of bacteria (Dettol brand)
5 sterilized falcon tubes
1 10 ml syringe without needle
1 timer
Tap waterScotch tape
Pre-experimental preparations:
1, squeeze pure lime juice from Small Limes bought from supermarket, into 1 labeled falcon tube.
2, squeeze pure lemon juice from Green Seedless Lemon bought from supermarket, into 1 labeled falcon tube.
3, squeeze normal hand soap and antibacterial hand soap into respective labeled falcon tubes.
4, test the pH of lime juice and lemon juice for data analysis to see which contains more citric acid.
5, prepare sufficient distilled water obtained from school lab into 1 labeled falcon tube.
6, cleanse the syringe with distilled water.
7, rinse right thumb and index finger under tap water.
Procedure:
(Day 1)
1, Prepare 6 lidded agar plates.
2, Inoculate 1 agar plate with the uncleaned left thumb by streaking in a systematic, even, S shaped pattern across the agar. Use the entire finger and not just the finger tip. Lid and label the plate.
3, Clean the left index finger with lime juice. Use the syringe to extract 5ml of lime juice from the falcon tube and pour evenly onto the finger. Scrub evenly and firmly with right thumb and index finger 10 strokes. Let the lime juice stay on the finger for another 10 seconds. Rinse finger under running water for 10 seconds.
4, Repeat Step 2 with the cleaned left index finger.
5, Cleanse the syringe with distilled water and right thumb and index finger under tap water.
6, Clean the left middle finger with lemon juice by repeating Step 3.
7, Repeat Step 2 with the cleaned left middle finger.
8, Repeat step 5.
9, Clean the left ring finger with normal (BRAND) hand soap by repeating step 3.
Materials and Apparatus:
18 prepared agar petri dishes
20 ml of pure lime juice
20 ml of pure lemon juiceDistilled water
20 ml of normal hand soap (brand: )
20 ml of antibacterial hand soap that claims to kill 99.9% of bacteria (Dettol brand)
5 sterilized falcon tubes
1 10 ml syringe without needle
1 timer
Tap waterScotch tape
Pre-experimental preparations:
1, squeeze pure lime juice from Small Limes bought from supermarket, into 1 labeled falcon tube.
2, squeeze pure lemon juice from Green Seedless Lemon bought from supermarket, into 1 labeled falcon tube.
3, squeeze normal hand soap and antibacterial hand soap into respective labeled falcon tubes.
4, test the pH of lime juice and lemon juice for data analysis to see which contains more citric acid.
5, prepare sufficient distilled water obtained from school lab into 1 labeled falcon tube.
6, cleanse the syringe with distilled water.
7, rinse right thumb and index finger under tap water.
Procedure:
(Day 1)
1, Prepare 6 lidded agar plates.
2, Inoculate 1 agar plate with the uncleaned left thumb by streaking in a systematic, even, S shaped pattern across the agar. Use the entire finger and not just the finger tip. Lid and label the plate.
3, Clean the left index finger with lime juice. Use the syringe to extract 5ml of lime juice from the falcon tube and pour evenly onto the finger. Scrub evenly and firmly with right thumb and index finger 10 strokes. Let the lime juice stay on the finger for another 10 seconds. Rinse finger under running water for 10 seconds.
4, Repeat Step 2 with the cleaned left index finger.
5, Cleanse the syringe with distilled water and right thumb and index finger under tap water.
6, Clean the left middle finger with lemon juice by repeating Step 3.
7, Repeat Step 2 with the cleaned left middle finger.
8, Repeat step 5.
9, Clean the left ring finger with normal (BRAND) hand soap by repeating step 3.
10, Repeat Step 2 with the cleaned left ring finger.
11, Repeat step 5.
12, Clean the left little finger with Dettol antibacterial hand soap by repeating Step 3.
13, Repeat Step 2 with the cleaned left little finger.
14, Repeat step 5.
15, Clean the right middle finger with distilled water by repeating Step 3.
16, Repeat Step 2 with the cleaned right middle finger.
17, Seal all agar plates with Scotch tape and leave for 24 hours in a warm location of about 28 degrees C, out of direct sunlight.
(Day 2)
18, Repeat Steps 1-17 with another 6 agar plates, using control on RMF, lime juice on LT, lemon juice on LIF, normal hand soap on LMF, antibacterial soap on LRF, distilled water on LLF.
19, Observe the first 6 plates from Day 1. Record the amount of bacteria growth by organizing the bacteria colonies using a chart of various bacteria colony sizes and counting the number of colonies. Also record the different types of bacteria that grow. Take photographs.
(Day 3)
20, Repeat steps 1-17 with another 6 plates, using control on LLF, lime juice on RMF, lemon juice on LT, normal hand soap on LIF, antibacterial hand soap on LMF, distilled water on LRF.
21, Observe bacteria growth on the plates from Days 1 and 2.
(Day 4)
22, Repeat step 19 on plates from Days 1, 2, and 3.
(Day 5)
23, Repeat step 19 on plates from Days 2 and 3.
(Day 6)
24, repeat step 19 on plate from Day 3.
25, Organize the data, compare from different plates and analyse.
Friday, May 27, 2011
More research on agar and bacteria culture
General information about agar:
1, Chemically, agar is a polymer made up of subunits of the sugar galactose, and is a component of the cell walls of several species of red algae that are usually harvested in eastern Asia and California.
2, Agar's chief use is as a culture medium for various microorganisms, particularly for bacteria
3, Agar is preferred over regular gelatin for culturing bacteria because agar will not be degraded (eaten) by bacteria. Also, it is firmer and stronger than gelatin.
" For students growing bacteria at home without the supervision of a teacher (for example, investigating bacteria growth at various places around the house), it's important to use an agar formulation that does not preferentially grow one kind of bacteria over another. The worst case would be one that preferentially grew pathogenic bacteria. Therefore, we recommend a plain nutrient agar, of which LB agar is a subtype.There are many different suppliers for LB agar. Because some suppliers will not sell to students directly, you may have to have your teacher order for you. If you are doing a project that involves inoculation and plate streaking, we highly recommend conducting the experiment at a school lab under teacher supervision. "Preparing bottled agar and plates
Although pre-poured agar plates are available, one can make agar plates from tablet, powdered, or bottled agar by following a few simple instructions. Agar kits usually come with detailed instructions on how to prepare plates, and below are sample procedures for reference. When in doubt, be sure to clearly read the instructions and ask for help if needed (either consult a teacher or call the technical help line of the agar kit supplier).
I think I will be using bottled agar or, if possible, pre-poured plates:
"Preparing Bottled Agar:
- Loosen the bottle cap, but do not remove the cap while heating.
- Warm the agar bottle in a hot water bath or in the microwave until it becomes liquid.
- After opening the cap, pass the neck of the agar bottle through a flame to sterilize it. Do not lose the cap!
- While pouring the agar, open the Petri dish lid as little as possible, hold it at an angle, and make sure the lid is kept directly over the Petri dish.
- Pour enough melted agar into each sterile plastic Petri dish to cover 1/8" of the bottom. Cover the lid of the Petri dish immediately.
- Place agar plates on a counter top to cool and set. Agar medium will set like stiff gelatin at room temperature.
- Pass the neck of the agar bottle through flame again before applying the cap.
Preparing Pre-Poured Plates: If plates have been refrigerated, set them out and allow them to warm to room temperature.
Storage: Stack agar plates upside down in the refrigerator. Do Not Freeze! The purpose of placing the plates upside down is to prevent condensation from dripping down onto the agar surface which could then facilitate movement of organisms between colonies.
About the incubator:
I will ask my Mother to take my plates to her lab for incubation and will proceed with observations at her lab. So the incubator is settled.
About the transfer of bacteria by contact:
"
1. Prepared petri dishes should be refrigerated until used and always stored upside down (i.e media in upper dish, cover on bottom). This keeps condensation which forms in the lid from dropping onto and disrupting the bacteria growing surface.
2. When ready to use, let dishes come to room temperature before taking samples (about one hour).
3. Without tearing the agar surface, inoculate the dish by gently pressing fingers, finger nails, coin, etc onto agar surface. (Direct contact of lips or tongue is NOT a good idea.)
4. Replace cover on dish, tape closed, and label each dish so you know the source of the bacteria. Store upside down.
5. Let grow in undisturbed warm location, ideally in an environment around 100° F (37° C) - not in sunlight or on a heating register.
6. You should see growth within a couple of days. The dishes will start to smell which means the bacteria are growing.
7. Make observations and keep records of what you see growing in each dish. Can you make any conclusions about what objects had the most bacteria?
8. Before disposing of dishes in the trash the bacteria should be destroyed. Pour a small amount of household bleach over the colonies while holding dish over sink. Caution - do not allow bleach to touch your skin, eyes or clothes. It will burn!"
Thursday, May 26, 2011
Emergency
Oh no...
I need to produce my own agar!!!
And without supervision of experienced teacher!
This means that my experiment has every chance of going very wrong.
More to do:
1) find out how to make agar
2) buy materials for agar
3) buy masking tape
4) check teacher's schedule
5) check which teacher knows about agar and bacteria
6) check how much time is needed to make agar
7) plan the time to mak agar
8) plan the time to do experiment
I need to produce my own agar!!!
And without supervision of experienced teacher!
This means that my experiment has every chance of going very wrong.
More to do:
1) find out how to make agar
2) buy materials for agar
3) buy masking tape
4) check teacher's schedule
5) check which teacher knows about agar and bacteria
6) check how much time is needed to make agar
7) plan the time to mak agar
8) plan the time to do experiment
My Email to Ms Tan
Dear Ms Tan,
For my SIP I will be investigating with bacteria, as you will remember, and I decided to do observations of 3 batches of bacteria, and I will observe each batch of bacteria on 3 individual days. Therefore I would be doing the experiment on 5 days, initiating the second batch and observing the first batch on Day 2, initiating the 3rd batch while observing the 1st and 2nd batch on Day 3, and so on.
I would need 18 petri-dishes with agar jelly for bacteria culture, which is the bulk of the apparatus I would need, aside from the bacteria incubator. I have attached the complete requisition form. I am not sure if I would need apparatus like droppers and cotton swabs - but I think it is okay to just pour the liquids onto my finger and just rub my finger on the jelly directly.
Since I need to do the experiment on 5 days, I need to start it on 30 May, next Monday, so it will finish on next Friday. I will be coming to the lab everyday at the same time to enhance the accuracy of the experiment. Please help me arrange the lab usage.
Please help me arrange the equipment, materials and lab usage. Thank you!
Yours,
Biqing
To Do List!!!
1, Grow bacteria. I have some serious doubts about if bacteria will grow if I simply stroke the agar jelly thingum. I am scared that they won't grow; if bacteria don't grow even for the control my experiment is doomed. One thing: should I use cotton swabs with water? Would it better enable bacteria to get onto the jelly surface?
To do:
- Try out growing bacteria at home
-Do research about how people grow bacteria/transfer
- ask people about if bacteria will transfer easily by contact.
-find that bacteria culture worksheet!!
2, Pilot test for washing hands. How can I wash hands so that it is most fair for each substance tested to have the same space and time to function on the hands? Now i'm thinking to 1) pour 50mm3 of liquid onto my finger 2) scrub it with two fingers (same fingers) of my other hand by stroking firmly 10 times
3) Let the substance remain on my hand for another 15 seconds. 4) rinse finger under water for 10 seconds.
But i need to test out this washing hands method.
3, Confirm the lab and equipment arrangements for next Monday. I don't know whether Ms Tan needs the hard copy since I emailed her the soft copy of the requisition form. I need to check.
4, Get the materials for the experiment on Monday.
-lemons
-lime
-pH testing paper
-test-tube-like containers from Mom's lab, to be sterilized by boiling water, to carry a fixed amount of each liquid to school.
-prepare lemon juice and lime juice by squeezing.
5, Write out the complete run-through plan of actual experiment -- preparation of cultures. Run through it in my mind completely.
6, Other stuff: email my appendix D, tell Ms Tan I am not using ImageJ (cannot understand how it works).
7, Thing to bring on experiment day:
-camera
-stationary
-plenty of paper
-containers containing lime juice, lemon juice, normal soap, antibacterial soap
To do:
- Try out growing bacteria at home
-Do research about how people grow bacteria/transfer
- ask people about if bacteria will transfer easily by contact.
-find that bacteria culture worksheet!!
2, Pilot test for washing hands. How can I wash hands so that it is most fair for each substance tested to have the same space and time to function on the hands? Now i'm thinking to 1) pour 50mm3 of liquid onto my finger 2) scrub it with two fingers (same fingers) of my other hand by stroking firmly 10 times
3) Let the substance remain on my hand for another 15 seconds. 4) rinse finger under water for 10 seconds.
But i need to test out this washing hands method.
3, Confirm the lab and equipment arrangements for next Monday. I don't know whether Ms Tan needs the hard copy since I emailed her the soft copy of the requisition form. I need to check.
4, Get the materials for the experiment on Monday.
-lemons
-lime
-pH testing paper
-test-tube-like containers from Mom's lab, to be sterilized by boiling water, to carry a fixed amount of each liquid to school.
-prepare lemon juice and lime juice by squeezing.
5, Write out the complete run-through plan of actual experiment -- preparation of cultures. Run through it in my mind completely.
6, Other stuff: email my appendix D, tell Ms Tan I am not using ImageJ (cannot understand how it works).
7, Thing to bring on experiment day:
-camera
-stationary
-plenty of paper
-containers containing lime juice, lemon juice, normal soap, antibacterial soap
Tuesday, May 24, 2011
Proposal
APPENDIX D
Science Investigative Project
Project Proposal Form
Name: | Qiu Biqing ( 20 ) | Sec 2/13 |
Topic of investigation : | Type of hand cleaning agent that remove bacteria most efficiently |
A | Observations made |
On television there are many advertisements about antibacterial hand soap that can kill 99.9% of bacteria. On the other hand there are people who use ointments made from natural substances as antiseptics. I want to find out the amount of bacteria removed by each type of cleaning agent and hence the antibacterial properties of the two unconventional hand cleaning agents. I would also compare the amounts of bacteria removed by natural and commercial antiseptics to see if there can be a substitute for antibacterial soap in nature. | |
B | Research Question |
Which type of agent among lime juice, lemon juice, water, normal hand soap and antibacterial hand soap removes bacteria from the hand most efficiently? | |
C | Hypothesis statement |
The antibacterial hand soap will remove bacteria from the hand most efficiently while water will remove bacteria from the hand least efficiently. | |
D | A short summary of research done on the area of investigation |
All types of bacteria can be found on your hands depending on what you touch, including many types of pathogenic bacteria. Normal hand soap removes bacteria physically. The bacteria on the hands take refuge under the surface lipids layer of the skin. Water is not able to dissolve the lipids layer; however, soap emulsifies the oil by forming a ‘bridge’ between polar water molecules and non-polar oil molecules, allowing water to mix well with oil. The alkaline components in soap also help to break down the surface fats layer, which is slightly acidic. Therefore normal soap does not kill the bacteria but enables them to be flushed away from the hand when rinsed with water. Antibacterial hand soap, in addition to the emulsifying properties of normal soap, contains active antibacterial chemicals which kill bacteria and microbes. A common such chemical is triclosan. However, research shows that there is not much difference between amounts of bacteria removed by either kinds of soap – normal soap can remove 95% of the bacteria, while antibacterial soap can remove 97%. (exact source unclear). Citric acid is able to kill bacteria by destroying their cell membranes. Food scientists have also proven that product made from citric acids and grapefruit oil removes microbes from fruits during food manufacturing more effectively than chlorine dioxide, killing reportedly 99.9999% of bacteria. (The striking similarity with claims about antibacterial soap makes the experiment much more interesting.) Citric acid is found in high amounts in lime and lemon. Lemon juice contains 1.44g/oz and lime juice 1.38g/oz of citric acid respectively. | |
E | Bibliography (Please refer to RS Students’ Handbook in RS Folder on Inet regarding APA Style Format) |
Wikipedia, (18 May 2011). Antibacterial soap. Wikipedia. Retrieved May 24, 2011, from http://en.wikipedia.org/wiki/Antibacterial_soap WikiAnswers, (unknown). How does soap work to clean things? WikiAnswers. Retrieved May 24, 2011, from http://wiki.answers.com/Q/How_does_soap_work_to_clean_things UAB Medicine, (18 February 2008). Hand washing. UAB Health System. Retrieved May 24, 2011, from http://www.health.uab.edu/17728/ Renee Miller, (unknown). About the bacteria on your hands. eHow. Retrieved May 24, 2011, from http://www.ehow.com/about_4571973_bacteria-hands.html WikiAnswers, (unknown). What is in lemon juice that kills bacteria? WikiAnswers. Retrieved May 24, 2011, from http://wiki.answers.com/Q/What_is_in_lemon_juice_that_kills_bacteria University of Idaho (2008, June 26). Food Scientists Confirm Commercial Product Effectively Kills Bacteria In Vegetable Washwater. ScienceDaily. Retrieved May 24, 2011, from http://www.sciencedaily.com/releases/2008/06/080625122930.htm Kristina L, Penniston M. D. and others, (March 2008). Quantitative Assessment of Citric Acid in Lemon Juice, Lime Juice, and Commercially-Available Fruit Juice Products. Pubmed Central. Retrieved 24 May 2011, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2637791/ |
Discussion with Ms Tan
I saw Ms Tan just now and she raised some ideas mostly regarding my method which I think is very usable:
1, She suggested that I do not grow bacteria first and then put in the agent as it would be different from the way we usually wash our hands, and too tedious anyway. Instead, I would wash/treat/rinse (haven't figured out exactly how to apply the substance...need to research on the way people use organic substances as antiseptics) one of my finger using one of the substances each time, and then use the cotton swab to swipe from my finger and spread on the bacteria culture. And use one uncleaned finger for bacteria culture to use as control (original amount of bacteria on our hands.)
2, Observe the bacteria growth from the cultures after 24 hours, 48 hours, 72 hours.
3, Need to repeat the experiment a few times for more accurate results.
4, For analysis, compare the samples with each other rather than with the control (before-after). See how natural products compare with commercial products.
5, To measure results correctly, use ImageJ (a software - haven't tried out yet). It can help me calculate the area of bacteria. And the type too? (see colour).
Things to do:
1, arrange lab/equipment usage. (first week of June hols - each time i take observation I can start a new batch, 3 batches, equipment needed - 18 agar jelly sets.)
2, No need to measure pH now i think, or maybe just for lime and lemon to see in which fruit the citric acid present is stronger.
3, Figure out a way to clean and keep fingers unclean that would be fair and leave me with enough fingers. (for the lack of hand area I can't do all 3 batches at one go; but i can try to solve this problem..)
4, Research on how people use/claim to use organic substances to clean their hands.
5, Research on how people use hand soap to clean their hands.
6, Settle on a uniform but fair method.
7, settle research question, hypothesis etc.
8, DO SCIENCE PROPOSAL.
1, She suggested that I do not grow bacteria first and then put in the agent as it would be different from the way we usually wash our hands, and too tedious anyway. Instead, I would wash/treat/rinse (haven't figured out exactly how to apply the substance...need to research on the way people use organic substances as antiseptics) one of my finger using one of the substances each time, and then use the cotton swab to swipe from my finger and spread on the bacteria culture. And use one uncleaned finger for bacteria culture to use as control (original amount of bacteria on our hands.)
2, Observe the bacteria growth from the cultures after 24 hours, 48 hours, 72 hours.
3, Need to repeat the experiment a few times for more accurate results.
4, For analysis, compare the samples with each other rather than with the control (before-after). See how natural products compare with commercial products.
5, To measure results correctly, use ImageJ (a software - haven't tried out yet). It can help me calculate the area of bacteria. And the type too? (see colour).
Things to do:
1, arrange lab/equipment usage. (first week of June hols - each time i take observation I can start a new batch, 3 batches, equipment needed - 18 agar jelly sets.)
2, No need to measure pH now i think, or maybe just for lime and lemon to see in which fruit the citric acid present is stronger.
3, Figure out a way to clean and keep fingers unclean that would be fair and leave me with enough fingers. (for the lack of hand area I can't do all 3 batches at one go; but i can try to solve this problem..)
4, Research on how people use/claim to use organic substances to clean their hands.
5, Research on how people use hand soap to clean their hands.
6, Settle on a uniform but fair method.
7, settle research question, hypothesis etc.
8, DO SCIENCE PROPOSAL.
Monday, May 23, 2011
Random ideas to be shot off
1, can coke reused from the coke-and-mentos experiment produce the same reaction? reused as in i find a way to channel erupted coke into a container and use them for the experiment again.
2, the idea in 1 itself can be used and an experiment - can reused coke work?
3, does coke taken out of its original packaging work in the mentos experiment? in all my research no one seems to address this issue. but by some explanations - that the coke geyser comes from the CO2 in the coke - would point to that coke transferred into another bottle would not work, as the CO2 in coke would be lost?
4, DOES ph affect the outcome? since no one seems to be sure about the cause of this phenomenon....pH can affect the results for all we know.
2, the idea in 1 itself can be used and an experiment - can reused coke work?
3, does coke taken out of its original packaging work in the mentos experiment? in all my research no one seems to address this issue. but by some explanations - that the coke geyser comes from the CO2 in the coke - would point to that coke transferred into another bottle would not work, as the CO2 in coke would be lost?
4, DOES ph affect the outcome? since no one seems to be sure about the cause of this phenomenon....pH can affect the results for all we know.
Details for this experiment
Aim: this experiment has two inter-related aims:
1) to find out if antibacterial hand soap really kills as much bacteria as claimed, with comparison to normal hand soap.
2) to find out if there can be an alternative for hand soap in lime juice and lemon juice that kills as much bacteria as the antibacterial hand soap or at least the normal hand soap.
(Research to back up experiment aim: citric acids are able to kill/inhibit bacteria by breaking down their cell membranes.
And even though the mechanism of removing bacteria using normal hand soap and antibacterial hand soap is a bit different, it would still be interesting to find out if what is supposed to happen in theory really does happen in products of the market.)
Materials and Apparatus:
10 petri-dishes of agar jelly for bacteria culture
Pure lime juice
Pure lemon juice
Distilled water
Normal hand soap
Hand soap that claims to kill 99.9% of bacteria (probably Dettol brand)
Sterilized cotton swabs
Sterilized droppers
Masking tape
Bacteria culture machine (in where bacteria can breed well)
Procedure:
1, Prepare 8 petri dishes of agar jelly-based bacteria culture. (Even though only 5 would be used later, the extra cultures are to make sure if there are cultures that do not turn out well enough for experiment, there would be replacements. If the logistics are available, that is.) Wet sterilized cotton wipes with sterilized/distilled water and swipe from the hand three strokes systematically. Spread evenly on the agar jelly of Petridish 1. Close the lid on the sample immediately after this is done.
2, Do the same for all other petri-dishes.
3, Seal each petri-dish with masking tape.
4, Put all petri-dishes in the bacteria culture machine (?) and let the bacteria develop for 24 hours. (?)
5, In the mean time, measure the pH of pure lime juice, pure lemon juice, distilled water, normal liquid hand soap and 99.9% bacteria-killing hand soap using pH test paper.
6, Also draw up a chart to measure the amount of bacteria by classifying colonies according to their diameters of 1mm, 2mm, 5mm, etc.
7, Back to the lab-select 5 petri-dishes of bacteria culture that are the most desirable (criteria: with distinctive colonies of bacteria for easy counting, with only bacteria and no mould on it). Measure the amount of bacteria on it by counting using the classifying chart of colony sizes.
8, Measure out 50mm of each type of liquid using a sterilized dropper and place each liquid onto a sterilized cotton swab. (using different uncontaminated droppers if possible).
9, Spread out the lime juice evenly onto one petri-dish using the cotton swab. Label this clearly 'Sample Lime Juice'.
10, Do similarly for different test liquids.
11, Seal the petri-dishes back and replace them into the bacteria culture machine for another 24 hours.
12, After 24 hours, observe and measure the amount of bacteria on each sample again.
13, 24 hours after this, observe and measure the amount of bacteria on each sample again.
14, After yet another 24 hours, observe and measure the amount of bacteria on each sample again.
15, Record and analyse all findings. Calculate the percentage change in the amount of bacteria as this would be more accurate. Present data in a clear table and/or graph.
That is the methodology. There seem to be many areas to do further research on.
1) Are 24 hours enough/suitable for enough cell development to be the interval between observation taken of bacteria?
2) Is the school lab open on Sundays?
3) What kind of bacteria is likely to be present on our hands?
4) What if i encounter different kinds of bacteria (those of different colours)? the experiment would be more interesting.......
1) to find out if antibacterial hand soap really kills as much bacteria as claimed, with comparison to normal hand soap.
2) to find out if there can be an alternative for hand soap in lime juice and lemon juice that kills as much bacteria as the antibacterial hand soap or at least the normal hand soap.
(Research to back up experiment aim: citric acids are able to kill/inhibit bacteria by breaking down their cell membranes.
And even though the mechanism of removing bacteria using normal hand soap and antibacterial hand soap is a bit different, it would still be interesting to find out if what is supposed to happen in theory really does happen in products of the market.)
Materials and Apparatus:
10 petri-dishes of agar jelly for bacteria culture
Pure lime juice
Pure lemon juice
Distilled water
Normal hand soap
Hand soap that claims to kill 99.9% of bacteria (probably Dettol brand)
Sterilized cotton swabs
Sterilized droppers
Masking tape
Bacteria culture machine (in where bacteria can breed well)
Procedure:
1, Prepare 8 petri dishes of agar jelly-based bacteria culture. (Even though only 5 would be used later, the extra cultures are to make sure if there are cultures that do not turn out well enough for experiment, there would be replacements. If the logistics are available, that is.) Wet sterilized cotton wipes with sterilized/distilled water and swipe from the hand three strokes systematically. Spread evenly on the agar jelly of Petridish 1. Close the lid on the sample immediately after this is done.
2, Do the same for all other petri-dishes.
3, Seal each petri-dish with masking tape.
4, Put all petri-dishes in the bacteria culture machine (?) and let the bacteria develop for 24 hours. (?)
5, In the mean time, measure the pH of pure lime juice, pure lemon juice, distilled water, normal liquid hand soap and 99.9% bacteria-killing hand soap using pH test paper.
6, Also draw up a chart to measure the amount of bacteria by classifying colonies according to their diameters of 1mm, 2mm, 5mm, etc.
7, Back to the lab-select 5 petri-dishes of bacteria culture that are the most desirable (criteria: with distinctive colonies of bacteria for easy counting, with only bacteria and no mould on it). Measure the amount of bacteria on it by counting using the classifying chart of colony sizes.
8, Measure out 50mm of each type of liquid using a sterilized dropper and place each liquid onto a sterilized cotton swab. (using different uncontaminated droppers if possible).
9, Spread out the lime juice evenly onto one petri-dish using the cotton swab. Label this clearly 'Sample Lime Juice'.
10, Do similarly for different test liquids.
11, Seal the petri-dishes back and replace them into the bacteria culture machine for another 24 hours.
12, After 24 hours, observe and measure the amount of bacteria on each sample again.
13, 24 hours after this, observe and measure the amount of bacteria on each sample again.
14, After yet another 24 hours, observe and measure the amount of bacteria on each sample again.
15, Record and analyse all findings. Calculate the percentage change in the amount of bacteria as this would be more accurate. Present data in a clear table and/or graph.
That is the methodology. There seem to be many areas to do further research on.
1) Are 24 hours enough/suitable for enough cell development to be the interval between observation taken of bacteria?
2) Is the school lab open on Sundays?
3) What kind of bacteria is likely to be present on our hands?
4) What if i encounter different kinds of bacteria (those of different colours)? the experiment would be more interesting.......
Another New and Better Idea
I decided yesterday that I should open up my options.....why just chem? I'm really interested in physics too, but really I can't think of any physics experiment that is feasible. However, I have another idea.
I would test whether liquid hand soap that claims to kill 99.9% of all bacteria really do kill that much bacteria. Actually I have already thought of this idea before but I was put off by the fact that I cannot observe bacteria conveniently. However, now I think that I can develop bacteria cultures easily in our school labs, Moreover, using bacteria from my hands, it would fit in the experiment about hand soaps as the bacteria-killing agent in hand soaps would be targeting bacteria commonly found on hands, if there are distinctive types of bateria there.
For the control for this experiment, I would use a) a non-bacteria-killing hand soap or b) water. I can do a comparison between the two different types of hand soaps or I can test the ability to kill bacteria by the same hand soap but of different states of dilution by water, for example, 25% diluted, 50% diluted, 75% diluted and not diluted at all, as well as a control of water.
But then, I had another idea in incorporating chemistry into this almost purely bio experiment. i can try killing bacteria with different substances: water, lime juice, lemon juice, normal hand soap, bacteria-killing hand soap. The essence of this experiment is the different pH of the independent variables. Because I know that too acidic or alkaline substances would kill bacteria, but since the underlying (or should I say, overall) purpose of this investigation is to find out if other, natural, non-harmful substances can kill bacteria on hands as well and therefore replace hand soap, and strong acids like HCl will definitely damage the human skin, I cannot use strong acids that would definitely kill bacteria for this experiment. This also adds a mystery to the experiment, the result is not known (at least not yet, I still need further research): can lime juice and lemon juice kill, at the very least with a small extent, bacteria?
This post is too long so I would post my procedure and other notes in the next post. The proposal seems to be due this week and some say that it is graded. :(( i would also need to arrange for coming back to school labs during school hols.
I would test whether liquid hand soap that claims to kill 99.9% of all bacteria really do kill that much bacteria. Actually I have already thought of this idea before but I was put off by the fact that I cannot observe bacteria conveniently. However, now I think that I can develop bacteria cultures easily in our school labs, Moreover, using bacteria from my hands, it would fit in the experiment about hand soaps as the bacteria-killing agent in hand soaps would be targeting bacteria commonly found on hands, if there are distinctive types of bateria there.
For the control for this experiment, I would use a) a non-bacteria-killing hand soap or b) water. I can do a comparison between the two different types of hand soaps or I can test the ability to kill bacteria by the same hand soap but of different states of dilution by water, for example, 25% diluted, 50% diluted, 75% diluted and not diluted at all, as well as a control of water.
But then, I had another idea in incorporating chemistry into this almost purely bio experiment. i can try killing bacteria with different substances: water, lime juice, lemon juice, normal hand soap, bacteria-killing hand soap. The essence of this experiment is the different pH of the independent variables. Because I know that too acidic or alkaline substances would kill bacteria, but since the underlying (or should I say, overall) purpose of this investigation is to find out if other, natural, non-harmful substances can kill bacteria on hands as well and therefore replace hand soap, and strong acids like HCl will definitely damage the human skin, I cannot use strong acids that would definitely kill bacteria for this experiment. This also adds a mystery to the experiment, the result is not known (at least not yet, I still need further research): can lime juice and lemon juice kill, at the very least with a small extent, bacteria?
This post is too long so I would post my procedure and other notes in the next post. The proposal seems to be due this week and some say that it is graded. :(( i would also need to arrange for coming back to school labs during school hols.
Sunday, May 22, 2011
Research and New Idea
This few days I've been doing research about the effect detergent on skin. Summary of the research: Detergent removes the layer of lipids on skin because of the alkaline nature of detergents by saponification, therefore subjecting skin to contact dermatitis.
However, this runs into a problem as how can I test about the effect of detergent on skin? I decided I can use chicken skin, which has some similar properties to human skin, but how can I measure the amount of lipids on it?
there are two tests that I can try: the grease spot test, which involves pressing a spot to a plastic bag (it would turn translucent if it contains lipids) and the Sudan red lipids test, which can only be tested in liquids (like the ethanol emulsion test) and for doing this I have to puree the chicken skin first. I don't think the grease spot test is too accurate. The Sudan red test would be attemptable.
Another problem: I wanted to test the effect of pH in the detergent on the lipids on chicken skin. However, would detergent with changed pH still be detergent? This would contradict the aim of my experiment. Another option is to test the effect of temperature of detergent in affecting the lipids on skin.
In the mean time, I have another idea: the type of fruit juice stain that would be easiest to be removed by common detergent. In doing my research I came across another idea, that lemon juice is an excellent stain remover for food based stains, and seem to work better in sunlight. Possible experiment questions that arise:
1, Which fruit juice stain is removed most easily by lemon juice?
2, Which type of food stain is removed most easily by lemon juice?
3, What is the effect of sunlight on the removal of stains by lemon juice?
4, What is the effect of salt on stain removal by lemon juice?
More seemed to be needed in these areas. In the next Bio lesson I shall ask Ms Tan about the chicken skin idea, whether it is feasible.
(I am not an active blogger under all circumstances and it's scary when I saw some classmates' blogs......stressed out)
However, this runs into a problem as how can I test about the effect of detergent on skin? I decided I can use chicken skin, which has some similar properties to human skin, but how can I measure the amount of lipids on it?
there are two tests that I can try: the grease spot test, which involves pressing a spot to a plastic bag (it would turn translucent if it contains lipids) and the Sudan red lipids test, which can only be tested in liquids (like the ethanol emulsion test) and for doing this I have to puree the chicken skin first. I don't think the grease spot test is too accurate. The Sudan red test would be attemptable.
Another problem: I wanted to test the effect of pH in the detergent on the lipids on chicken skin. However, would detergent with changed pH still be detergent? This would contradict the aim of my experiment. Another option is to test the effect of temperature of detergent in affecting the lipids on skin.
In the mean time, I have another idea: the type of fruit juice stain that would be easiest to be removed by common detergent. In doing my research I came across another idea, that lemon juice is an excellent stain remover for food based stains, and seem to work better in sunlight. Possible experiment questions that arise:
1, Which fruit juice stain is removed most easily by lemon juice?
2, Which type of food stain is removed most easily by lemon juice?
3, What is the effect of sunlight on the removal of stains by lemon juice?
4, What is the effect of salt on stain removal by lemon juice?
More seemed to be needed in these areas. In the next Bio lesson I shall ask Ms Tan about the chicken skin idea, whether it is feasible.
(I am not an active blogger under all circumstances and it's scary when I saw some classmates' blogs......stressed out)
Thursday, May 19, 2011
Ideas for Science Investigative Project
I have come up with a list of ideas for the SIP (though nearly all of them are unacceptable):
1, Investigate how the change in pH or temperature of coke affects how much coke/the speed at which coke spurts out when a mento is put in. This would investigate, I think, how the amount or the pressure of carbon dioxide in the coke is affected by the independent variable. However due to high expenses and the amount of resources wasted, the idea is not accepted. (However, now I come up with an idea to measure the amount of coke that comes out by channeling it to a measuring container, so it will not make a mess and easier to measure, and determine the pressure by measuring the speed at which the coke reaches the container. Still, it does not solve the expenses problem, really a lot of coke is needed.)
2, Investigate in what ways detergent is harmful to different things. this idea is still quite undeveloped because I wanted to investigate things as I want to investigate about how detergent harms human hands. Because human hands cannot be used for the experiment, I was thinking to use plant parts (epidermis) that has similar physical characteristics as the human skin. But the substances on plant epidermis are really different from those on human skin. I have to do research about what substances in detergents exactly damages the skin.
3, Other ideas: which type of food attracts the most ants (my mother does not allow this as I want to do it at home; at any other place it would be hard to monitor closely and constantly.) Another idea is the effect of temperature on the rate that corrosive household chemicals corrode. But upon second thought, it might be too dangerous.
So now I need to do research about detergents and human skin. However, so far my research has turned up nothing yet.....
1, Investigate how the change in pH or temperature of coke affects how much coke/the speed at which coke spurts out when a mento is put in. This would investigate, I think, how the amount or the pressure of carbon dioxide in the coke is affected by the independent variable. However due to high expenses and the amount of resources wasted, the idea is not accepted. (However, now I come up with an idea to measure the amount of coke that comes out by channeling it to a measuring container, so it will not make a mess and easier to measure, and determine the pressure by measuring the speed at which the coke reaches the container. Still, it does not solve the expenses problem, really a lot of coke is needed.)
2, Investigate in what ways detergent is harmful to different things. this idea is still quite undeveloped because I wanted to investigate things as I want to investigate about how detergent harms human hands. Because human hands cannot be used for the experiment, I was thinking to use plant parts (epidermis) that has similar physical characteristics as the human skin. But the substances on plant epidermis are really different from those on human skin. I have to do research about what substances in detergents exactly damages the skin.
3, Other ideas: which type of food attracts the most ants (my mother does not allow this as I want to do it at home; at any other place it would be hard to monitor closely and constantly.) Another idea is the effect of temperature on the rate that corrosive household chemicals corrode. But upon second thought, it might be too dangerous.
So now I need to do research about detergents and human skin. However, so far my research has turned up nothing yet.....
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