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Hamden Hall Journal for High School Research Spring, 2011 Volume 1, Number 1 6/1/2011

Editors Chief Editors Dan Horvath ‗12 Nikhil Trehan ‘12

Associate Editors Adam Berkley ‗11 Austen Kim ‗12 Brian Pacelli ‗12 David Wang ‗12

Production Editors Klemens Gowin ‗13 Dana Lee ‗13

Publishing Brian Pacelli ‗12

Faculty Advisor Frank Gasparro, PhD


Contents Editors ......................................................................................................................................... 1 Project Reports .............................................................................................................................. 3 The Effect of Varying Fertilizer Concentrations on the Growth of Chlorella Cultures (Chlorella Regularis).................................................................................................................. 4 Spectroscopic Determination of Iron in Two Different Brands of Hand Warmers .......... 17 Research Reports........................................................................................................................ 28 The Relationship between Ambulatory Blood Pressure and Cognitive Performance .. 29 The Effect of Fertilization and Environmental Factors on Water Quality in the Upper Cove River Watershed ........................................................................................................... 40 The Inhibition Of Candida albicans By Eugenia Aromatica Oil and Citrus Paradisi Seed Extract....................................................................................................................................... 49 Improving solar water disinfection (SODIS) with a photoreactive TiO2/SWCNT composite on plastic PET bottles .......................................................................................... 62


Project Reports


The Effect of Varying Fertilizer Concentrations on the Growth of Chlorella Cultures (Chlorella Regularis)

Christian Montano Hamden Hall Country Day School 1108 Whitney Ave, Hamden Connecticut 06517 Monday, May 2, 2011


Abstract Fertilizer is used to maintain a healthier lawn. However over fertilization is common, and this leads to the run off of the excess fertilizer. When it rains or the lawn gets watered, the excess fertilizer is swept away. The accumulation of fertilizer in storm drains is harmful to organisms that use cellular respiration because; the unusually high amount of fertilizer causes algae to grow to unnaturally high levels. As the algae dies, bacteria eats it, and CO2 is released. If the amounts of fertilizer are varied, then the cultures of Chlorella exposed to the nutrients in the fertilizer will have a higher Chlorella density then the ones not exposed to the nutrients in the fertilizer. The materials used were 16 screw volumetric flasks, a gallon of spring water, Chlorella, Liquid Fertilizer, Spectrophotometer, and a light source. The experiment had three replicates of all tests, and also had three control samples. There were four tests conducted, all with the similar procedure; the only difference was the amount of fertilizer in each test. The first trial started with the recommended .33% fertilizer solution, and each trial had twice the pervious‘s percent of fertilizer. The data collected was both qualitative and quantitative data, using the spectrophotometer and a visual scale from 1-10. All the data collected supported the hypothesis, for the experimental trials all had at minimum a 25% transmittance decrease. The data collected could help better understand the effects of fertilizer pollution into water ways. It was very clear that even the recommend dosage of fertilizer has a significant impact on algae growth. If everyone in a neighborhood used fertilizer, it is very clear how much an aquatic ecosystem could be harmed.


Introduction The research problem addressed in this paper is the effect of different fertilizer concentrations on the growth of the fresh water algae (Chlorella Regularis). If the amount of nutrients (fertilizer) are varied, then the cultures of Chlorella exposed to the higher concentrations of nutrients in the fertilizer will have more growth then the ones exposed to none or lower concentration of fertilizer. Fertilizer is a common household item that allows the growth of healthier plants and lawn faster. Though the nutrients in fertilizer are necessary in growing healthy plants, they can have a harmful effect if they are misused. An overdose in certain nutrients can cause genetic mutations or plant death, while other times it causes plants to grow uncontrollably. (Staff, Cornell. "Eutrophication Experiments) If the amount of fertilizer is varied in an aqueous environment with only algae, then the effect of different fertilizers concentration on the algae‘s growth will be clear. As the percent solution of fertilizer increases, then the density of Chlorella in the culture should increase too. The independent variable for this experiment was the different fertilizer concentrations. The dependent variable for this experiment was the amount of Chlorella growth. Fertilizer is used throughout the world, and its effect is visible throughout the world too. People often over fertilize their plants, and when it rains or the fertilized area gets wet, the excess fertilizer is washed down the storm drains and dumped into reservoirs and ultimately the ocean. Once the chemicals and nutrients are in the water they have the same effect on marine plants, as they do on terrestrial plants. (Science Daily. NOAA) the algae and other plants grow exponentially because of the unnaturally high levels of nutrients. The abnormally high plant density 6|Page

causes light to be blocked from reaching the bottom of the pond. A lack of light at the mid and lower levels of the pond is harmful to life because, plants life cannot photosynthesize, and the temperature of the water drops. As fish and plants die, bacteria decompose their bodies. The bacterium that digests the dead organisms releases CO2, as a product of cellular respiration. This process quickly makes the pond inhospitable to life. Eutrophication is the named for this cycle. Eutrophication is defined as ―The process by which a body of water acquires a high concentration of nutrients, especially phosphates and nitrates. These typically promote excessive growth of algae. As the algae die and decompose, high levels of organic matter and the decomposing organisms deplete the water of available oxygen, causing the death of other organisms, such as fish.‖ Hypoxia is another important term when talking about Eutrophication. Hypoxia is defined as, ―a phenomenon that occurs in aquatic environments as dissolved oxygen, becomes reduced in concentration to a point detrimental to aquatic organisms living in the system. (Science Daily. NOAA)


Materials and Methods Materials The materials used were: 15 screw top vials (29 mm x 81 mm, 40ml), one volumetric flask (100ml), 3.785 liters of spring water (Poland Spring) 40ml of water will be the amount in each vial, Chlorella (Chlorella Regularis) from Connecticut Valley Biological Supplies, Liquid Fertilizer (Miracle Grow Multi-Purpose 32oz), Spectrophotometer (Spectronic 20, Bausch & Lomb), Light Source (Grow- Light), Air displacement Pipette (100-1200uL) Method This experiment has thirteen steps. Step One: Clean the 15 vials. Step Two: Put 40ml of Chlorella in screw top vials. Step Three: Label tubes with test number, solution percent, and initials. Make three replications for each test trial. Step Four: Using the AirDisplacement Pipette, put 138.5uL of fertilizer in the .33% solution tube. (Repeat three times) Step Five: Using the Air-Displacement Pipette, put 277uL of fertilizer in the .66% solution tube. (Repeat three times) Step Six: Using the Air-Displacement Pipette, put 554uL of fertilizer in the 1.32% solution tube. (Repeat three times) Step Seven: Using the Air-Displacement Pipette, put 1108uL of fertilizer in the 2.64% solution tube. (Repeat three times) Step Eight:

Take transmittance percentage using the

spectrophotometer, for all 15 tests. (There are four steps to finding the transmittance of light percentage, using the Spectrophotometer. One: Follow instructions printed on spectrophotometer for setting control sample transmittance and set spectrophotometer 8|Page

to a 680 wavelength. Two: Clean the tube that is made for holding liquid solutions in the spectrophotometer. Three: Fill the spectrophotometer test tube to the designated volume. Four: Take transmittance reading, and clean tube when finished. Repeat each of the four steps for number of trials.) Step Nine: Put tests under Grow-light for 96 hours. Step Ten: Take transmittance percentage using the spectrophotometer, for all 15 tests. Step Eleven: Put tests under Grow-light for 48 hours. Step Twelve: Take transmittance percentage using the spectrophotometer, for all 15 tests. Step Thirteen: Clean up the experiment. Fig.2

Fig. 1

15 Prepared vials, ready to be placed under grow light. (Step eight) Chlorella after being exposed to grow light for 96 hours. (Step Ten)

In this experiment both qualitative and quantitative data were collected.


quantitative data that was collected was the light transmittance percentage of each trial. Transmittance percentage is the percent of light that is able to pass through the


solution. For measuring the light transmittance with particles the size of Chlorella, a 680 wavelength was used. (Selman, Mindy, et al. "EUTROPHICATION AND)


qualitative data that was taken was the visual grade from one to ten. (One being clear as pure water, and ten being dark green) This experiment lasted 144 hours, or six days. The only daily maintenance that was needed on days when data wasn‘t collected, was keeping the test vials under the grow light, and making sure that there were no leaks. In this experiment the constants were; the temperature, the amount of light, and the light source. The experimental method used allowed for control over these parameters, by keeping a stable environment, and use of the same equipment. Since each trial was separated from the outside world, once the proper amount of fertilizer was put inside the tube, and the tube was placed beneath the light source nothing except experimental error could cause a problem to arise.

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The Effect of Different Fertilizer Concentrations on the Growth of Chlorella


Light Transmittance (in percent)

100% 100% 94.70% 95.70% 92.70% 91.70%



80% 69.30% 60%


68% 57.30%

44% 40% 33%

37% 26.30%


0% 0 hrs

96 hrs

144 hrs

Time of Growth (in hours)

Data Processing & Presentations The five different solution percentages used were; 0%, .33%, .66%, 1.32%, and 2.64%. The Chlorella growth will be measured in two ways; one by the percentage of light that can pass through the solution (transmittance) and the other will be a visual numeric grade from one to ten. (One being normal transparency for water, ten being dense green.) There was correlation between the amount of fertilizer in the test, and the density of Chlorella culture. As the percentage of fertilizer in the solution increased, the transmittance percent decreased. As seen in figure two there is a distinct visual difference between each test solution‘s appearances. Table one is a collection of the qualitative data that was collected. Figure five is a graph of the data that was collected

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in this experiment. The visual aid of a graph helps show the significant difference in transmittance percentage of each test. Figure six is a photo of one of each test concentration at the end of the experiment. In figure five the blue diamonded shaped line represents the 0.00% fertilizer solution, the red square represents the .33% fertilizer solution, the green triangle represents the .66% fertilizer solution, the purple ―X‖ line represents the 1.34% fertilizer solution, and the teal asterisk line represents the 2.64% fertilizer solution.

The Effect of Different Fertilizer Concentrations on the Color of a Chlorella Culture Table.1

Reading 1(Initial Avg)

Reading 2 (96hrs Avg )

Reading 3 (144hrs Avg)

.0% Solution (Control) .33% Solution




Percent of Change (Total) 1.3





.66% Solution





1.32% Solution





2.64% Solution





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Fig. 6

From left to right the vials are the: 0% Solution (Control), .33% Solution, .66% Solution, 1.32% Solution, 2.64% Solution.

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Conclusion & Evaluations The data collected supported the original hypothesis of, ―If the amount of nutrients (fertilizer) are varied, then the cultures of Chlorella exposed to the nutrients in the fertilizer will have more growth then the ones not exposed to the nutrients in the fertilizer.‖ All but two trials supported the hypothesis. The two trials that didn‘t support it, when averaged still kept the data around where it was predicted to be. (Science Clarified Aglobloom, Rank, Jason) The control trials had on average 96% transmittance at the end of the experiment. This is a huge difference from the other trials that had; 68%, 57.3%, 37%, and 26.3% transmittance, supporting the hypothesis further more. There was evidence of some errors while conducting this experiment. Two trials had unusually high transmittance. The errors didn‘t affect the data too much though. This experiment did have very finite limits though. To increase the accuracy and types of data this experiment collects several thing could be changed; (1) taking more transmission reading with the spectrophotometer (2) making more test concentration and trials (3) conducting the test in different environments (4) adding other organisms in the tests (5) and monitoring the oxygen levels just to name a few. The quantitative data proved to be more valuable than the qualitative data, because it was decisive nondebatable data. The qualitative data could become unreliable because of human error. (Since it was a matter of opinion) The data that was collected in this experiment could be used to develop more eco-friendly fertilizers, and similar tests could be conducted to find the individual nutrient(s) that have the biggest impact in causing algal blooms. Tests to find the impact of pesticides on aquatic life could be done just like this experiment, but only using different pesticides instead of fertilizer.

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Literature Cited 1)

Anderson, Donald, Patricia Glibert, and Joann Burkholder. "Harmful Algal Blooms and Eutrophication: Nutrient Sources," Estuaries Aug. 2002: 704-726. Web. 25 Apr. 2011. < Anderson_etal_2002_Estuaries_29903.pdf>.

2) D'Angleo, Gina. Help Setting Up, Use of Equipment. Honors Biology. Hamden Hall. 8 Apr. 2011. Address. 3) Garn, Herbert S. "Effects of Lawn Fertilizer on Nutrient Concentration in Runoff." USGS (July 2002): n. pag. Web. 27 Mar. 2011. 4) Plant Care . N.p., Winter 2011. Web. 29 Mar. 2011. < lawn-fertilizing.html>. <>. 5)

Science Daily. NOAA, 24 Apr. 2008. Web. 28 Mar. 2011. <>.

6) Selman, Mindy, et al. "EUTROPHICATION AND." World Research Institute Mar. 2008: n. pag. WRI. Web. 25 Mar. 2011. < eutrophication_and_hypoxia_in_coastal_areas.pdf>. 7) SMAYDA, T. J. 1997. Harmful algal blooms: Their ecophysiology and general relevance to phytoplankton blooms in the sea. Limnology and Oceanography 42:1137â&#x20AC;&#x201C;1153.pdf> 9) Staff, Cornell. "Eutrophication Experiments." Environmental Inquiry: All. Web. 14 Apr. 2011. <

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Eutrophication_Experiments.pdf>. 10) Rank, Jason. "Science Clarified Aglobloom." Science Clarified. Google, 2011. Web. 14 Apr. 2011. < Eutrophication.html>. 11) Wikipedia. N.p., 1 Mar. 2011. Web. 30 Mar. 2011. < wiki/Chlorella>

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Spectroscopic Determination of Iron in Two Different Brands of Hand Warmers Nikhil Trehan Hamden Hall Country Day School 1108 Whitney Ave. Hamden, CT

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Abstract The purpose of this experiment was to determine the amount of iron in two different brands of hand warmers and to analyze their relative efficiencies. To determine the amount of iron in two different brands of hand warmers, 0.1 g specimens were dissolved in concentrated HCl. Aliquots of these solutions were diluted with 0.002 M 1,10phenanthroline and then analyzed at 510 nm using a spectrophotometer. A standard calibration curve was prepared by dissolving specific known amounts of iron (II) ammonium sulfate with stoichiometric amounts of the phenanthroline. Then, by taking into to account the various dilution factors the amount of iron present in each solution was calculated. The efficiency of the hand warmer brands (in 째C/sec) was measured by taking the initial slope of a temperature vs. time graph for the hand warmer packets enclosed in an insulated glove. Results indicate relatively small differences in heating efficiency as related to the iron content.

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Introduction Hand warmers are used in skiing and other winter sports to release warmth slowly over time as a controlled amount of oxygen reacts with powdered iron in an exothermic rusting reaction. The main electrochemical processes are: O2 + 4 e- + 2 H2O → 4 OH- (Controlled reaction involving oxygen in the air) Fe → Fe2+ + 2 e− (Reaction involving iron in hand warmer packets) Fe2+ + 2 H2O Fe(OH)2 + 2 H+ (Reaction involving water in hand warmer packets) Fe3+ + 3 H2O  Fe(OH)3 + 3 H+ (Reaction involving water in hand warmer packets)

While elemental iron is the principal component in a hand warmer, other ingredients are present: vermiculite to retain heat, salt, and water to promote the complex exothermic iron reaction as shown above as well as activated carbon as a catalyst. While the reaction may be thought to involve the formation of Fe 2O3, the overall process is a much more complicated electrochemical process hence the need for water and salt in the hand warmer packets.

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Phenanthroline was added to the hand warmer solutions to bond to the iron and produce a complex ion with a much greater ability to absorb light meaning that lower amounts of iron could be detected: C12H8N2 + Fe2+ ď&#x192;  [Fe(phen)3]2+ Fig.1) Phenanthroline

Fig.2) [Fe(phen)3]2+

In Fig. 1 and Fig. 2 are, respectively, the structures of Phenanthroline and ferroin, the iron/Phenanthroline complex formed when Phenanthroline is added to the contents of hand warmer packages after dissolving the contents in concentrated HCl.

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Materials and Methods This experiment was an improvement of a previous method to find iron in hot hands—the old method did not involve the use of phenanthroline. The old method was based on the spectroscopic analysis of iron-HCl solutions by determining the absorbance at 330 nm, which was the wavelength limit of . The contents of completely reacted Little Hotties and Heat Factory hand warmer packets were dissolved in HCl. The Phenanthroline method is more accurate and more sensitive because once the Fe-phen complex forms, the spectrum is shifted into the visible region (λmax at 508 nm). To measure the concentration of iron present in the hand warmers, a calibration curve was obtained by measuring the absorbances at 508 nm of several known concentrations of iron (II) complexed with 1,10-phenanthroline and using a plot vs. concentration of iron. The absorbance was measured using a two-piece Vernier spectrometer connected to a laptop and cuvettes filled with solution. An Excel trend plot gave a slope of 7550 A/M, which corresponds to the absorbance of 1.00 M iron-phenanthroline complex. With this calibration curve, it was possible to use aliquots of the iron solutions in HCl mixed with the phenanthroline to measure the absorbance at 508 nm and to find the corresponding iron (II) concentration. Thus, the mass of iron could be calculated. The complex also included a buffer and a reducing agent, hydroxylamine hydrochloride, to ensure the iron solution contained only Fe 2+ ions. Because vermiculite, which also contains some iron, also dissolved in the HCl to a limited extent, a vermiculite control experiment was conducted. A magnifying glass, light, and thin graphite rod were used to separate the lustrous vermiculite pieces from

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the darker reacted hand warmer contents and find the mass percent of vermiculite in hand warmers. Results Table 1) Hand Warmers Data Table


Fe Mass (g) (old method)

Fe Mass (g)

Fe Mass (g)

(improved method Trial 1)

(improved method Trial 2)

Little Hotties




Heat Factory




In Table 1, iron masses using the old method and improved method are displayed. The old method refers to spectroscopic analysis of hand warmer contents in concentrated HCl, and the improved method refers to the spectroscopic analysis (using a molar extinction coefficient of 508 nm) of those hand warmer contents in HCl complexed with

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Phenanthroline. It is evident that the Phenanthroline made a drastic difference in hand warmer iron mass determination.

Figure 3) Standard Curve for Iron Phenanthroline Complex

Standard Curve for Iron-Phenanthroline Complex 2.5



y = 7548.5x + 0.0486 R2 = 0.9975

1.5 1 0.5 0 0







Concentration (M)

In Figure 3 is the standard curve that was used to relate absorbance data to concentration and eventually mass data. The mathematical relation of the above graph allowed for this. Each solution used to plot this curve contained: ferrous ammonium sulfate as a compound containing iron, hydroxlamine hydrochloride as a reducing agent, sodium acetate as a buffer, and phenanthroline to bond to the iron.

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Figure 4) Efficiency Graph (â&#x20AC;&#x2022;Little Hottiesâ&#x20AC;&#x2013;, Efficiency Test #2)

An opened hand warmer packet was placed inside an insulated glove and the temperature was collected using Vernier probes. The above figure shows the best fit line taken through 2000 seconds of heat efficiency data. The slope of the line was the average efficiency over these 2000 seconds. Using the same method of best fit line over 2000s, other efficiency data was obtained.

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Table 2) Efficiency Over 2000s Data Table Brand

Efficiency (째C/s) (Trial 1)

Efficiency (째C/s) (Trial 2)

Little Hotties



Efficiency Average (째C/s) (Trial 3) Efficiency Over 2000 seconds (째C/s) .01640 .0137

Heat Factory





In Table 2 the efficiency data for both brands of hand warmers is recorded. Little Hotties, which had a greater mass of iron than Heat Factory, had consistently higher heating efficiency and a higher average heating efficiency. This data suggests that there is a direct relation between iron mass and heating efficiency in hand warmers. Table 3) Vermiculite Mass Table Mass of Hand Mass of Mass of Mass Percent Warmer Sample Without Vermiculite in of Vermiculite Sample Vermiculite Sample in Sample .109 .106 .003 2.8% .103 .099 .004 3.9% .110 .107 .003 2.7% .502 .488 .014 2.8% Average Mass Percent of Vermiculite in hand warmers = 3.1% Vermiculite is the only ingredient in the hand warmers besides the iron itself that contains iron, so it is the only one that could significantly affect absorbance data. However, the very low average mass percent of Vermiculite in hand warmers (3.1%) and of iron in vermiculite (9.97%) allows for the assumption that vermiculite in hand warmers does not significantly affect spectroscopic data.

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Discussion/Summary The data collected in this experiment suggests a direct relation between iron content in hand warmers and heating efficiency. Also, more trials need to be carried outâ&#x20AC;&#x201D;there is not enough data to evaluate which method is more accurate, and there are drastic differences between iron mass using both methods. This experiment suggests that hand warmers with more iron content will have a stronger effect over time. Do other ingredients affect heating efficiency more than iron? Which other metals have more heating efficiency than iron?

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Literature Cited "Wellesley College Intro Chem Lab Manual: Lab 04-Analysis of Ferrous Iron in a Vitamin Pill."Redirect to Wellesley College Web Site. Web. 16 May 2011. <>. "Vermiculite Mineral Data." Mineralogy Database. Web. 31 May 2011. <>. "Rust." Wikipedia, the Free Encyclopedia. Web. 31 May 2011. <>.

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Research Reports

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The Relationship between Ambulatory Blood Pressure and Cognitive Performance

Jennifer Dalecki Amity Regional High School 25 Newton Rd. Woodbridge, CT 06525

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ABSTRACT Although some research has linked cardiovascular risk factors to declines in cognitive function; other studies have not demonstrated a clear relationship. One explanation for discrepant findings is differences in the methods used to measure blood pressure (BP). Most studies acquired a measure of clinical blood pressure (BP). Clinical BP, can vary because of the white-coat effect and various other factors, is often an unreliable indicator of an individualâ&#x20AC;&#x2DC;s actual blood pressure. In contrast, 24-hour ambulatory blood pressure (ABP) has been shown to be more reliable in studies linking BP to brain changes believed to be caused by hypertension such as white matter abnormalities. The purpose of this study was to examine the relationship between 24hour ABP and decline in cognitive performance in adults over 75. It is hypothesized that those with higher ABP readings will show more evidence of cognitive decline, whereas those with lower ABP will see less evidence of cognitive deterioration. Using participants from a four year longitudinal study, ABP measures were related to results from cognitive performance testing. Results were analyzed by dividing the participant pool into high, middle, and low BP levels and assessing the decline in cognitive performance over the span of four years. Analysis showed no significant correlation between 24-hour blood pressure and memory and speed of processing measures.

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INTRODUCTION Although some research has linked cardiovascular risk factors to declines in cognitive function; other studies have not demonstrated a relationship. In a study conducted by Raz and Rodigue, white matter hyperintensities (WMH) found in the prefrontal and temporal regions of the brain were linked with a decrease in executive functioning (Raz). Under the assumption that white brain matter abnormalities correlate with blood pressure levels, research by Wakefield concluded that high blood pressure levels correlate with cognitive decline (Wakefield). Other studies have found inconclusive evidence or results suggesting negligible correlations. The explanation for discrepant findings is in the methods used to measure blood pressure (BP). Most studies acquired a measure of clinical blood pressure (BP), meaning a BP taken in a professional setting by a doctor or clinician. Clinical BP can vary because of the white-coat effect, which is characterized by high stress and heightened blood pressure while in the presence of a doctor, and various other factors and, in turn, is an unreliable indicator of an individualâ&#x20AC;&#x2DC;s actual blood pressure. In contrast, 24-hour ambulatory blood press (ABP) has been shown to be reliable (Marchiando). Long term reproducibility of ABP was found to be statistically superior to the reliability of clinical BP measures (Wakefield). Based on the inconclusive findings of past studies, this study is designed to examine the correlation between ambulatory blood pressure and cognitive function. It is essentially intended to correlate memory and speed of processing abilities with blood pressure levels. It is hypothesized that as an individualâ&#x20AC;&#x2DC;s blood pressure increases, their likelihood to do well on tests of cognitive function will be significantly less likely than their counterparts with lower or midrange blood pressure readings.

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This hypothesis was developed based on the few

studies that have illustrated a weak correlation between blood pressure and cognitive performance. This hypothesis was tested using 71 participants over the age of 75. These participants were divided into three groups based on systolic ambulatory blood pressure figures. The participant pool was split into high, middle, and low blood pressure in the process of analysis. The group was evaluated using a battery of standardized assessments for cognitive functioning including the Wechsler Test of Adult Reading (WTAR), Stroop Color and Words Test, Trails Test, and List Call. In order to preserve the validity of this experiment, variables were held constant. The participants in the study are near equal mix of male and female participants who live in middle to upper class communities. The battery of tests administered to each participant remained constant. In order to ensure that the order of the testing will not impact results, test order was counterbalanced. Hypothetically, this variation in order should negate and cancel out any impact that order can have on results and conclusions. Data was collected over the course of four years in a consistent laboratory environment. Data for each participant is to be collected on an individual basis so as to prevent participants from influencing each othersâ&#x20AC;&#x2DC; responses. Following the data collection, data was analyzed using various tables, graphs, and appropriate statistical analysis. Single Variance ANOVAs were used to analyze the relationship between the systolic blood pressures of the three groups and performance on tests of cognitive function.

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MATERIALS & METHODS Subjects This sampling of participants consisted of 71 participants between 75 and 89 years of age. Subjects were recruited from the community for a 4-year longitudinal study. From 312 individuals screened by telephone, 164 were eligible, consenting individuals, of whom 117 came for a physical examination. Subjects were assessed for exclusion criteria including medication, systemic conditions, and neurological diseases that can compromise mobility; MiniMental State Examination score of less than 24; corrected distance vision worse than 20/70; unstable cardiovascular disease; pulmonary disease requiring oxygen; inability to walk 10 meters independently; weight greater than 113.5 kg; presence of a pacemaker or other metallic device or implant; excessive alcohol intake; and expected life span less than 4 years. Subjects deemed eligible provided informed consent and then underwent neurological and cognitive assessment. Participants and assessors were blinded to clinical, mobility, and imaging outcomes. The protocol was approved by the institutional review board of UCONN Health Center in Farmington, Connecticut.

Assessment Tools The relationship between ambulatory blood pressure and cognitive functioning was evaluated using comprehensive measures of memory and speed of processing. Memory and speed of processing was evaluated because as fluid abilities, they are both associated with degradation in older age (Coon). The WTAR, or Wechsler Test of Adult Reading, is composed of various reading tasks that are used to measure IQ and memory abilities (Bowden). This test has been deemed a test of both content and criterion validity because test-retest reliability coefficients range from 0.67 and 0.97 (Test Review). The Stroop Task is a psychological test of

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mental vitality and flexibility. The task takes advantage of natural ability to read words more quickly and automatically than colors, and requires that individuals identify the color font of a word over the color name that the word spells out. Again, like the WTAR, the Stroop Color and Word Test had high test-retest reliability (Van der Elst). The Trails Test Part B is a speeded test that measures visual attention, visual scanning, sequencing, and cognitive flexibility. Part B requires participants to follow a trail of numbers while coping with interference with letters. The normative data for Trails Test Part B is very reliable because it takes into account factors such as age and level of education (Trail Making Test). Statistical Analysis Participants were divided into three groups based on systolic ambulatory blood pressure. Groups were divided into high, middle, and low ambulatory blood pressure in relation to other blood pressure measures in the group. Essentially, this division was a means through which to compare participants against one another. Using this division of three groups, scores on the WTAR, Stroop Colors and Words Test, Trails Test, and List Call Test were analyzed. A single variance ANOVA was used to delineate the relationship between high, middle, and low blood pressure and scores on the tests of cognitive functioning.

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DATA & DISCUSSION OF RESULTS Figure 1: Mean WTAR Scores vs. Systolic Ambulatory BP

P-value: 0.161183

Figure 2: Mean Stroop Color and Words Test vs. Systolic Ambulatory BP

P-value: 0.420308

Figure 3: Mean Trails Test vs. Systolic Ambulatory BP

P-value: 0.882762

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Figure 4: Mean List Call Scores vs. Systolic Ambulatory BP

P-value: 0.570458

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CONCLUSION: The results of my experimentation indicate no significant correlation in ambulatory blood pressure levels and scores on tests of cognitive function. It does not appear that there is a distinctive trend relating ambulatory blood pressure and cognitive function. With each test, it would appear as though scores by those with high blood pressure are lower than those with middle and low blood pressure. This relates back to the hypothesis predicting that individuals with higher systolic blood pressure readings would do worse on tests of cognitive ability, specifically those regarding speed of processing and memory. Though seemingly matching the initial hypothesis, the collective spectrum of data is less promising. Across the board, individuals with the mid-range blood pressure had the highest mean scores on each form of cognitive testingâ&#x20AC;&#x201D;over both those with comparatively higher or lower blood pressure. With that, there is no clear positive or negative correlation seen in data analysis. Statistical analysis adds merit to my conclusion that no meaningful trend can be discerned between ambulatory blood pressure levels and scores on cognitive testing. This experiment consisted of one independent variable with three tiers (blood pressure levels) and several dependent variables (scores on WTAR, Stroop Color and Word Test, Trails Test, and List Call). This data was run through multiple Single Factor ANOVAs. It was determined that no measure of cognitive with relation to blood pressure levels was statistically significant. With the WTAR the p value was 0.161 â&#x20AC;&#x201C; significantly more than the necessary 0.05 value. Additionally, on the Stroop Color and Word test the p value was 0.420 and the Trails Test and List Call, p values were 0.882 and 0.570 respectively, reiterating the lack of correlation.

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There are undoubtedly limitations and errors that that should be addressed in future work. First and foremost, the size of my subject pool is limiting. Seventy-one participants divided into three groups near equal groups leaves merely twenty-three to twenty-four participants to represent each age bracket. The division of my total participant pool into smaller groups makes it nearly impossible to make entirely valid conclusions. Beyond the size of my participant pool, further errors include the volunteer bias of my participant pool. Participants were primarily from upper middle class, predominantly white communities, where health care is of great importance. These individuals are well cared for by their families, physicians, and specialized doctors and are an overly health conscious sampling of the general population. Moreover, it is important to acknowledge that in this study, I utilized data from the first year of the longitudinal study, when participants were at their youngest state. Perhaps, a clearer correlation would be seen using data from the second or third year of the study.

Most importantly, somewhat arbitrary division of my subject pool

into vaguely defined high, middle, and low blood pressure may have be an underlying cause of my inconclusive results. In addition to addressing these errors, in the future I would like to examine blood pressure and cognitive functioning using different evaluations of cognitive ability and mental processing, such as the California Computerized Assessment Package and RBANS Assessment Package. Also, integrating MRI imaging may also help bring the project one step further.

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WORKS CITED: Bowden, S.C. "Accuracy of the Wechsler Test of Adult Reading (WTAR) and National Adult Reading Test (NART) When Estimating IQ." Australian Psychological Society, 2007. Web. 12 Jan. 2011. <>. De Young, Raymond. "Stroop Task." University of Michigan, 2005. Web. 12 Dec. 2010. <>. Marchiando, Rod. "Automated Ambulatory Blood Pressure Monitoring: Clinical Utility in the Family Practice Setting." American Family Physician 67.11 (2003). Print. Raz, Naftali, Karen M. Rodrigue, and James D. Acker. "Hypertension and the Brain: Vulnerability of the Prefrontal Regions and Executive Functions." Behavioral Neuroscience 117.6 (2003): 1169-180. Print. Test Review Portfolio. Dallas, 2005. Cognitive Test Review. University of Dallas. Web. 31 Dec. 2010. "Trail Making Test." Neuropsychology & Behavioral Neuroscience. Web. 17 Jan. 2011. <>. Van Der Elst, Wim. "The Stroop Color Word Test." Maastricht University. Web. 27 Dec. 210. <>. Wakefield, Dorothy, Richard Kaplan, and Leslie Wolfson. "White Matter Hyperintensities Predict Functional Decline in." American Geriatrics Society 58.2 (2010). Print. Wakefield, Dorothy. "Wakefield Grant Proposal." UCONN Health Center. Web.

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The Effect of Fertilization and Environmental Factors on Water Quality in the Upper Cove River Watershed

Danielle Eldracher ( Zelun Wang ( Amity High School Science Research Program 25 Newton Road, Woodbridge, CT 0625

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Water samples were collected and tested using Vernier probes at 8 locations along the upper Cove River watershed in south central Connecticut for temperature, dissolved oxygen, dissolved nitrate (NO3-), pH, and conductivity within one hour of solar noon. Time, location, and environmental factors were observed and considered. Nitrate measurements were higher in a tributary (East Side Tributary) flowing from a golf course than in the control West Side Tributary, supporting the hypothesis that fertilizer runoff from a golf course may raise dissolved nitrate concentration. Results show that average nitrate concentrations were lower further downstream (0.4mg/L) suggesting that nitrate is being removed from the water by riparian wetlands. Also, average dissolved oxygen concentrations were higher (8.4mg/L) in the West tributary than in the East Side Tributary (6.7mg/L), indicating better water quality in the West Side (control) tributary. While some parts of the watershed may be affected by the golf course, the overall water quality of the upper Cove River watershed is healthy. Dissolved nitrate levels appear natural and do not exceed 1 mg/L. The pH levels fall within a healthy range for aquatic ecosystems. Dissolved oxygen concentrations were well above the minimum 3.0 mg/L necessary to sustain healthy aquatic life.

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Introduction The Cove River is a 7km long river, draining ~13 km 2 located in south central Connecticut. The hydrology of the upper Cove River watershed is interesting both at the local level and at the global level. One human activity that is of particular interest is the fertilization of a golf course at the northern end of the watershed. Runoff from fertilizer can add excess nitrate into rivers and lakes as nonpoint source pollution. Excess nitrate may lead to significant loss of aquatic life.

1, 2, 3

Also, the Maltby Lakes, part of the upper

Cove River watershed, is a potable reservoir. High nitrate concentration in drinking water (EPA Maximum Contaminant Level 10mg/L) is harmful to health and potentially fatal for infants.


Research suggests that riparian wetlands (soaked areas adjacent to

streams) effectively aid the removal of nitrate from water.


Water quality of the upper Cove River watershed was monitored from October, 2010 to February, 2011. Dissolved nitrate (NO3-) concentration was the focus of this study. Other indicators of water quality were also measuredâ&#x20AC;&#x201D;water temperature, dissolved oxygen concentration, conductivity, and pH. How do natural environmental factors and potential human activities on a golf course affect the water quality of the upper Cove River watershed throughout autumn and winter 2010 - 2011? The independent variables are the location in watershed and the date throughout the sampling period. The dependent variables are indicators of water quality â&#x20AC;&#x201C; temperature, dissolved nitrate concentration, pH, dissolved oxygen concentration, and conductivity. It is hypothesized that nitrate concentration will be higher in the East Side Tributary flowing from the golf course than in the control West Side Tributary, since the East Side Tributary is likely affected by golf course fertilization. 42 | P a g e


Also, nitrate concentrations will be lower further downstream, as combination of the

East Side Tributary with the West Side Tributary and with the lake will dilute nitrate concentration, and riparian wetlands along the stream may have a denitrifying effect.


Consistent sampling procedures were used, and all data is collected within 1 hour of solar noon 1

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Materials & Methods The upper Cove River watershed was visited at 2-week intervals throughout fall/winter of 2010-2011, weather permitting, within 1 hour of solar noon.



temperature was taken, and observations were recorded. Water from each site was collected in a bucket, and water temperature and dissolved oxygen concentration were immediately measured using Vernier probes. A water sample from each site was taken in a 50mL Falcon tube and brought back to the lab, where measurements of conductivity, dissolved nitrate concentration, and pH were measured using Vernier probes. 10

Sampling Locations

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Results Average By Location

Data vs Time (10/30/2010 to 2/12/2011) 20

Temperature (°C)


Dissolved Oxygen (mg/L)



6.0 4.0


2.0 0.0

5 0





Nitrate (mg/L) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

7 6.5 6

5.5 5 10/30/2010


Conductivity (µS/cm)

250 200 150 100 50 0 10/30/2010


Additional Tests Pine Needle Mixture Nitrate: 10.3 mg/L pH: 5.89 Conductivity: 305.7 µS/cm

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Snow Sample 1/1/2011 Nitrate: 0.2 mg/L pH: 7.10 Conductivity: 10.8 µS/cm

Snow Sample 2/12/2011 Nitrate: 0.2 mg/L pH: 6.30 Conductivity: 6.6 µS/cm

Discussion The water quality of the upper Cove River watershed is healthy. Possible effects of the golf course on dissolved nitrate concentrations in the water were observed. While nitrate concentrations in the East Side Tributary coming from the golf course were slightly higher than in the control West Side Tributary, the presence of the golf course does not negatively affect the water quality of the upper Cove River watershed. Nitrate concentrations measured do not exceed 1 mg/L, well below the EPA Maximum Containment Level of 10 mg/L.


Dissolved nitrate levels in the upper Cove River

watershed are similar to concentrations of naturally occurring nitrate.


Also, data

suggests that dissolved nitrate is filtered out as it flows through riparian wetlands between the spillway and the spillway outlet, as well as between the confluence and the confluence outlet. Measurements of pH indicate that the water is slightly acidic, with pH levels falling mostly within the normal range of 6.5 to 8.5 for natural water.



measurements did not deviate from expectations, since the watershed is densely populated by evergreens that add to the acidity of the soil. Observations suggest that natural fallen tree litter impacts pH. 7 Dissolved oxygen measurements also indicate that the upper Cove River watershed is healthy. Dissolved oxygen concentration varied between 6.3 mg/L and 10.2 mg/L, well above the minimum 3 mg/L necessary to sustain aquatic life without excess stress. 1 A limitation of this investigation is that fertilization schedules were not available from the Yale Golf Course. Without fertilization data, conclusions drawn concerning the effect of golf course activities on nitrate levels in the water are speculative. It can only

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be stated that fertilization is one possible factor, among others, that affects water nitrate levels. Data of the water chemistry of the upper Cove River watershed will continue to be collected at regular intervals until fall/winter of 2011. It would be ideal to obtain fertilization schedules from the golf course and permission to test the ponds on the golf course to better analyze the effect of fertilization on the water quality. Another potential study would focus on the northeastern section of the upper Cove River watershed, where the water quality is likely affected by suburban residential activities.

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Literature Cited 1. "Introduction." GLOBE Hydrology 2005. 22 Jan 2011 <>. 2. Mulholland, Patrick J. ―Stream denitrification across biomes and its response to anthropogenic nitrate loading.‖ Nature 452, 202-205 (13 March 2008) <> 3. Biello, David. "Fertilizer Runoff Overwhelms Streams and Rivers--Creating Vast "Dead Zones"." Scientific American 14 Mar 2008. 22 Jan 2011 <>. 4. "Drinking Water Contaminants." Drinking Water. 11 Jan 2011. US EPA. 22 Jan 2011 <>. 5. Hill, A.R. ―Nitrate removal in stream riparian zones.‖ Department of Geography, York University, 4700 Keele Street North York, Ontario, M3J 1P3, CANADA. <> 6. " Electrical Conductivity: Measuring Salts in Water." N.p., n.d. Web. 20 Jan. 2011. <> 7. "Why is pH Important?" N.p., n.d. Web. 20 Jan. 2011. <> 8. "Print A Solar Noon Calender." Solar Noon . Oct 2007. InternetWorks. 22 Jan 2011 <>. 9. Parliman, D.J., 2002, Analysis of nitrate concentration trends in 25 ground-waterquality management areas, Idaho, 1961-2001: U.S. Geological Survey WaterResources Investigation Report Report 02-4056, 60 p. 10. "Vernier Probes and Sensors." Products. Vernier Software and Technology. 9/28/2010 <>.

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The Inhibition Of Candida albicans By Eugenia Aromatica Oil and Citrus Paradisi Seed Extract.

Student: Esha Kaushik 1-(203)-557-0398

Advisor: Lauren Hauser 1-(203)-291-1414 ext. 5735 Weston High School 115 School Road Weston, CT 06883

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Normally present in the body as harmless bacteria, Candida albicans take up the opportunity to flourish and transform into an infectious yeast disease in individuals with a suppressed or compromised immunity. C. albicans was found to be completely inhibited by eugenia aromatica oil. Eugenol, which makes up 70%-90% of essential oils from eugenia aromatica, is known to have antifungal properties. Citrus Paradisi seed extract, commonly known as grapefruit seed extract, is known to improve immunity so that there will not be any further growth of C. albicans. This herb was also tested for its antifungal properties against C. albicans; and it successfully inhibited the yeast infection with an average inhibition zone of 28 mm. The Kirby Bauer method of sensitivity testing was employed to grow the organism and to test the susceptibility of the disease to the herbs. Eugenia aromatica oil was placed on a blood agar petri dish that was inoculated with C. albicans. The dish was placed in an incubator at 37째C for 24 hours and was found that Candida albicans was susceptible to eugenia aromatica oil with an average inhibition zone of 24 mm.

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Introduction: Candida albicans is normally present in the mouth, throat, intestines, the nonparasitical organisms in your intestine, which is the bowel flora, and the genitourinary tract as a harmless yeast bacteria that has the special function of determining and killing off harmful bacteria. Candidal growth is regulated as long as immune system is functioning properly, but when the immune system is compromised, the normally harmless bacteria takes up the chance to flourish and grows into an infectious yeast disease, morphing into a fungal form. In its fungal form, C. albicans is very invasive and tends to spread quickly. Rhizoids, which are root-like structures that are formed by the change in C. albicans structure, puncture the intestinal walls, which let undigested food into the blood stream, which lets the Candida itself spread throughout the bloodstream, this causes Candidiasis, which is when the C. albicans is present in the bloodstream and undetectable by the immune system, which causes the immune system to, as in most cases, attack itself. Eugenia aromatica oil is more commonly known as clove oil, and has been recognized as an effective toothache reliever, but recently scientists have been discovering the very effective antifungal properties of eugenol, which is the antifungal and active compound found in eugenia aromatica oil. Citrus paradisi seed extract is more commonly known as grapefruit seed extract (GSE). GSE is made up of bioflavonoids, which are known to help repair cells in the body; Hesperidin, a bioflavonoid found in GSE, is known to detoxify, enhance, support, and stimulate the immune system. It is also known that it is impossible for pathogenic microorganisms to grow resistant against GSE. 51 | P a g e

Materials: - Sterile inoculating loops - Sterile cotton applicators - Sterile pipettes - Sterile saline - 10 sterile vials - Prepared agar petri dishes - Candida albicans - 10 types - 10 microliter inoculating loop - Citrus Paradisi Seed Extract - Eugenia Aromatica Oil - Blood agar petri dish - Turbidity strips - Incubator - Auxanometer

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Procedure/Methods: Part I: Preparation Be sure to follow all Bridgeport Hospital Microbiology Lab safety procedures. First properly sterilize all materials before use. Obtain 22 agar petri dishes, and label 2 of the 22 plates ―Control‖ as the control group of this project. Then, label another 10 plates as ―Clove Oil‖, another 10 plates as ―GSE‖ for Grapefruit Seed Extract. Obtain 10 bottles and fill the bottles with pure saline, then label each bottle from 1 -10. Using a sterile inoculating loop, lightly scrape a small amount of the C. albicans onto the loop. Then take the inoculating loop and gently twirl inside the saline as to mix the C. albicans in the saline. Mix the saline and the C. albicans using the McArthur Mixer. Using the Turbidity Strip provided by Bridgeport Hospital Microbiology Lab, check the turbidity of the saline; repeat this saline and turbidity testing process with all 10 types of C. albicans provided by Bridgeport Hospital. If needed then use the sterile pipette to add more saline to the mixture, to lower the turbidity. Gently twirl a sterile cotton applicator in the saline labeled ―1‖. Part II: Testing Take the cotton applicator and inoculate 1 ―Clove Oil‖ plate and 1 ―GSE‖ plate using the streak-plate technique. Repeat this streak plate technique with all 20 plates, using the appropriate saline for every 2 plates (1 ―GSE‖ plate and 1 ―Clove Oil‖ plate) Gently add a drop of clove oil onto dishes labeled ―Clove Oil‖, and a drop of grapefruit seed extract on the dishes labeled ―GSE‖. Then place all the dishes in incubator at 36°C upside down for 24 hours for bacterial growth. 53 | P a g e

Part II: Observation After 24 hours, remove from incubator and observe zone of inhibition using an auxanometer and record the inhibition zone diameter. Then examine all groups under a microscope to see the growth and inhibition of Candida albicans. Take pictures of plates and repeat trials.

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Results Inhibition Zones for Candida Albicans

22 23 21 21 24

Clove Oil

Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6



28 31 24 29 34

GSE 0 0 0 0 0 0

Grapefruit Extract 0





Measurements in millimeters (mm) Figure 1

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Data Analysis This graph shows that GSE was a better inhibitor than eugenia aromatica oil (clove oil), and grapefruit extract. The average inhibition zone for GSE was 28 mm, the average diameter inhibition zone for clove oil was 24 mm, and the average diameter inhibition zone for grapefruit extract was 0 mm. This data also shows that GSE works better as an inhibitor than just grapefruit extract which may be because the seed of the fruit has a more concentrated amount of procyanidolic oligomer, thus more effectively inhibiting the Candida albicans yeast infection. Statistical Analysis Of Effectiveness Of Treatment Against C. albicans

Figure 2

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Clove Oil: - Mean: 24.0 - Standard Deviation: 4.56 - Hi: 33.0 - Low: 21.0 - Median: 22.5 - Average absolute deviation from media: 2.67

Citrus Paradisi Seed Extract: - Mean: 27.8 - Standard Deviation: 4.71 - Hi: 34.0 - Low: 21.0 - Median: 28.5 - Average absolute deviation from median: 3.50

Statistical Analysis

Citrus Parasidi Seed Extract and Eugenia Aromatica Oil turned out not to be statistically different. The mean of inhibition zones in Clove Oil was 24 mm, whereas the mean on inhibition zone in GSE was 27.8 mm, which is not a statistically significant difference. The standard deviation for GSE was 4.71 and the standard deviation for Clove Oil was 4.56, which shows that these two treatments are equally as effective and equally as antifungal when inhibiting Candida albicans.

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Discussion/Summary: The major findings in this experiment was the effectiveness of eugenia aromatica oil and citrus paradisi seed extract on C. albicans, and the modes of action of GSE and clove oil when they inhibit the Candida. These findings are important because the effectiveness piece of this experiment shows two highly effective and natural treatments for the yeast infection. Literature shows that GSE works better than most of the antibiotics used today. One of the study shows that GSE directly reduces Candida overgrowth, which could prevent cardiovascular damage caused by the toxins. It was also found that the anti-candida effects were dose dependent. Best thing found during all of the studies that there were no adverse effects even at higher dosages. Oligomeric proanthocyanidins (OPCs), found in GSE is almost 50 times more powerful antioxidant than vitamin E and 20 times more powerful than vitamin C. Many studies have revealed the benefits of GSE in cancer and heart disease treatments. GSE can also be used to reduce the toxicity of cancer drugs. Originally formulated in 1976 GSE is a naturally occurring combination of powerful ingredients including bioflavonoids, amino acids, fatty acids, saccharides, phenolic elements, tocopherols, ascorbic acid and dehydroascorbic acids. During 1989-90, an international research team examined the effects of GSE and compared this with 30 effective antibiotics and 18 proven fungicides. Grapefruit seed extract was very effective at very low concentrations and was found to perform as well as any and all of the tested agents without the harsh side effects. Although this experiment was not done with many trials to show the statistical significance, because of limitations in the lab where this experiment was conducted, the numbers shown in the results still portray the antifungal properties of GSE and clove oil. 58 | P a g e

This experiment could be repeated in large numbers, which would show the statistical significance and accuracy of the resulting data and hypothesis shown in this experiment. This lab was only done with 6 trials because of the limitations in the lab. Also, this experiment could also be conducted as a comparison of the inhibition of C. albicans with probiotics to show which treatment is more effective.

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Literature Cited: 1.


Bagchi D, Garg A, Krohn RL, Bagchi M, Tran MX, Stohs SJ. Oxygen free radical scavenging abilities of vitamins C and E, and a grape seed


extract in vitro. Res Commun Mol Pathol Pharmacol. 1997

Feb; 95(2): 179-89.

Candida Albicans. (2009). Health Encyclopedia - Diseases and Conditions [Symptoms of Candida Albicans]. Retrieved November 26, 2009, from TRUSTe website:


Davidson, R. (2002). Candida Albicans description. In Candida Cure.

Retrieved July 24, 2009, from http://www.candida-albicans-



Farr, G., Dr. (2002, February 24). Candida Albicans. In Women's Conditions / Candida Albicans (Yeast) [Description of Candida Albicans]. Retrieved November 25, 2009, from website:


Han Y. Synergic effect of grape seed extract with amphotericin B against disseminated candidiasis due to Candida albicans. Phytomedicine. 2007 November 14(11): 733-8.


Department of ImmunoMicrobiolgy, College of Pharmacy, Dongduk Women's University, 23-1 Wolgok-Dong

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Lorenz P, Roychowdhury S, Engelmann M, Wolf G, Horn TF.Oxyresveratrol and resveratrol are potent antioxidants and free radical scavengers: effect on nitrosative and oxidative stress derived from microglial cells. Nitric Oxide. 2003 Sep; 9(2): 64-76.


Padilla-Hudson, D., & Wittekind, S. (N.D.). Candida 1-2-3: Antifungals. In Naturally Thriving. Retrieved July 24, 2009,


Pole, S. (2006). Garlic. In Ayurvedic Medicine: The Principles of Traditional Practice (pp. 181-182). Pennsylvania: Elsevier Ltd.


Shea, R. (1997). Garlic. In Natural cures for Candida. Retrieved July 23, 2009, from


Shi J, Yu J, Pohorly JE, Kakuda Y. Polyphenolics in grape seeds-biochemistry and functionality.J Med Food. 2003 Winter; 6(4): 291-9.


Wertheim, T. Protozoology, London: Bailliere, Tindall & Cassel, 1844.

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Improving solar water disinfection (SODIS) with a photoreactive TiO2/SWCNT composite on plastic PET bottles

By Zizi Yu Amity Regional High School 25 Newton Road Woodbridge, CT 06525

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Approximately 1.1 billion people in the world lack access to safe drinking water, which leads to two million deaths a year due to waterborne diarrheal diseases. Solar disinfection (SODIS), a point-of-use water treatment method that uses UV radiation in sunlight to kill pathogenic organisms, was discovered by Professor Aftim Acra in the early 1980â&#x20AC;&#x2DC;s. Because SODIS relies largely on weather conditions, its efficiency varies greatly. The purpose of this study was to improve SODIS by coating plastic PET bottles with a TiO2 and a TiO2/SWCNT composite, a photocatalytic nanomaterial that exhibits strong antibacterial activity. Water samples were collected from the Quinnipiac River in Wallingford, CT and transferred into the bottles to be tested for bacteria at time intervals of 0 min, 180 min, and 360 min of sun exposure. Two trials were performed with the same bottles to test for bottle reusability, and bacterial concentrations were determined through serial dilutions and plate counting. Results show that the TiO 2/SWCNT composite coating was the most effective in meeting EPA standards, preventing bacterial growth in optimal temperatures, and producing strong coatings. The TiO2/SWCNT composite coating did kill more bacteria as hypothesized, but the full 360 min of sun exposure was required.

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Introduction The inadequate supply of safe drinking water is an issue that affects an estimated 1.1 billion people worldwide. In the 1980â&#x20AC;&#x2DC;s, Professor Aftim Acra discovered solar disinfection (SODIS), which uses UV radiation in natural sunlight to kill pathogenic organisms.


SODIS requires filling water into plastic polyethylene terephthalate (PET)

bottles and leaving them in the sun, making it a simple, environmentally sustainable, and virtually costless technology.[3] But despite its advantages, SODIS alone still faces certain challenges. Because it relies largely on specific weather conditions, its efficiency varies greatly. Many countries that lack clean water are located outside of the boundaries where SODIS is most effective.[3] SODIS alone also does not provide residual protection against bacterial regrowth.[3] To improve the SODIS treatment, this study utilizes titanium dioxide (TiO2) as a coating on plastic PET bottles. TiO2 is a metal oxide with many unique properties, including high photocatalytic activity, biological and chemical stability, nontoxicity, strong oxidizing activity, and low price.[8] Single-walled carbon nanotubes (SWCNTs) are also used; when combined with TiO2 in a composite, SWCNTs not only provide a larger surface area but also trap electrons transferred from TiO2, further enhancing oxidization and antibacterial potential.[1] The independent variable in this study is the type of coating, while the dependent variable is the concentration of bacteria found in the water. It is hypothesized that the TiO2/SWCNT composite coating will enhance the SODIS process by killing more bacteria and decreasing the required sun exposure time. The results from this study will be valuable in the development and application of low-cost, energy-efficient, and environmentallyfriendly methods of water purification for developing countries. 64 | P a g e

Materials & Methods

Synthesis of TiO2 and Composite Suspensions – The bottles were coated using a 10% w/v suspension. The TiO2 suspension consisted of 1g TiO2 powder and 10mL demineralized water; the composite suspension consisted of 50mg SWCNTs and 200mL water. 950mg TiO 2 powder was then added. The suspension was sonicated and heated until the water evaporated. One gram of the dried composite was then added to 10mL demineralized water and sonicated for 30 min. Bottle Preparation and Coating - The bottles were rinsed, filled with water, sonicated for 1 hour, and dried 48 hours at room temp. The suspensions were introduced into the bottles and shaken to obtain a homogenous film over the bottle wall. The bottles dried 24 hours at room temp, and then they were half-filled with water and shaken for 30 sec. to ensure no coating detached before use. Exposure to Sun - Nine bottles were tested: 3 blank controls, 3 TiO2 coating, and 3 TiO2/SWCNT composite. The bottles were filled with river water, placed inside an aluminum foilcovered solar reflector box, and left in the sun. Water samples were collected aseptically at 0, 180, and 360 min. The irradiation test was then repeated using fresh river water. Dilutions and Plate Counting - Water samples of 1.5mL were collected aseptically in microcentrifuge tubes. This was the 0x dilution (original sample). 100µL of this 0x sample were plated onto an agar plate with micropipette, and the cells were spread evenly using a metal cell spreader. Successive dilutions of 900uL sterilized water and 100µL of the previous dilution were also plated. Plates were incubated for 3 days and colony-forming units were counted. Absorbance Measurements - Samples were analyzed for absorbance and transmittance with a Vernier LabQuest probe and Red Tide Spectrometer. Spectrometer cuvettes were filled ¾ and light was shined at the samples. Absorbance was converted into % transmittance using an absorbance-%transmittance chart. 65 | P a g e


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Discussion/Summary Trial 1 â&#x20AC;&#x201C; 9/18/10 - Bacterial concentrations decreased significantly throughout the irradiation test. The blank control, the TiO2, and the composite started with average concentrations of 8500 cfu/mL, 34000 cfu/mL, and 13333 cfu/mL, respectively. At 180 min, the TiO 2 and composite bottles decreased to below half of the initial concentration, but the blank control still had roughly 63% of its initial bacterial concentration. At the end of the test, both TiO 2 and the composite had less than 6% of their original concentrations. The control, however, still had 30% of the initial bacteria remaining, demonstrating the benefits of the photocatalysts. Only the composite met the Environmental Protection Agency (EPA) standard for coliform bacteria (500 cfu/mL). Trial 2 â&#x20AC;&#x201C; 9/19/10- In the second trial there was no continuous decrease in bacterial concentration. The control, the TiO2, and the composite bottles started with an average of 3000 cfu/mL, 5500 cfu/mL, and 1800 cfu/mL, respectively. At 180 min, the blank control and TiO 2 reached 250% and 150% of the initial concentration, respectively. The cause of the increase is believed to be the increase in water temperature. The composite bottles, however, prevented growth, averaging 33% of its original concentration at 180 min. After 360 min, the blank control bottles still had 93% of its initial concentration, ending essentially where it began. The TiO 2 performed slightly better, but the benefits of the composite were evident as it ended with just 8% of its original concentration. Thus the composite not only killed bacteria but also prevented growth under optimal temperatures, which the control and TiO2 alone failed to do. Absorbance/% Transmittance - The high absorbance and low transmittance for the TiO2 indicate that it lost a good deal of coating. The composite bottles, however, experienced little to no coating loss as absorbance was similar to that of the blank control. This suggests that the composite not only killed more bacteria but also produced a more durable coating, making it the most advantageous choice to improve water purification in the SODIS method.

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Literature Cited

1. Yao, Yuan, Gonghu Li, Shannon Ciston, Richard M Lueptow and Kimberly A. Gray. "Photoreactive TiO2/carbon Nanotube Composites: Synthesis and Reactivity." Environmental Science Technology 42.13 (2008): 4952-957. 2. Li, Qilin, Shaily Mahendra, Delina Y Lyon, Lena Brunet, Michael V Liga, Dong Li, and Pedro J. Alvarez. ―Antimicrobial nanomaterials for water disinfection and microbial control: potential applications and implications.‖ Water Research 2.18(2008): 4591-4602. 3. Gelover, Silvia, Luis A. Gómez, Karina Reyes, and Teresa Leal. ―A practical demonstration of water disinfection using TiO2 films and sunlight.‖ Water Research 40. 17(2006):3274-80 4. Narayan, Roger. ―Use of nanomaterials in water purification.‖ Materials Today 13. 6(2010):44-46. 5. Cernigoj Urh, Stangar, Urska Lavrencic, Trebse Polonca, Krasovec Ursa Opara, and Silvia Gross. ―Photocatalytically active TiO2 thin films produced by surfactant-assisted sol-gel processing.‖ Thin Solid Films 495 (2006):327-332. 6. Ciston, Shannon, Richard M. Lueptow, and Kimberly A. Gray. ―Controlling biofilm growth using reactive ceramic ultrafiltration membranes.‖ Journal of Membrane Science (2009): 263-268 7. Meichtry, Jorge M., Hurng J. Lin, Ivana K. Levy, Eduardo A. Gautier, Miguel A. Blesa, and Marta I. Litter. ―Low-cost TiO2 photocatalytic technology for water potabilization in plastic bottles for isolated regions.‖ Photocatalyst fixation. Journal of Solar Energy Engineering 129 (2007):119-126 8. Akhavan, M. Abdolahad, Y. Abdi and S. Mohajerzadeh. ―Synthesis of titania/carbon nanotube heterojunction arrays for photoinactivation of E. coli in visible light irradiation.‖Carbon 47.14 (2009): 3280-3287 9. Heredia, Manuel and John Duffy. ―Photocatalytic destruction of water pollutants using a TiO2 film in PET bottles.‖ 1 Jan. 2011 10. Dean, J.A., ed. Lange's Handbook of Chemistry, New York : McGraw-Hill, 1973 11. USEPA Office of Water, Fact Sheet: National Primary Drinking Water Standards, EPA 570/9-91-012FS (August 1991). 12. Blauch, David N. "Spectrophotometry: Basic Principles." Virtual Chemistry Experiments. Davidson College Chemistry Resources, 2001. Web. 01 Jan. 2011. <>.

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Hamden Hall Journal for High School Research