Camphor and Rivanol (Ethacridine Lactate) - An interesting reaction

Two days ago, while trying to clean a pimple with an antiseptic camphor solution, I accidentally used ethacridine lactate (Rivanol) instead. After realizing this, instead of first cleaning the rivanol stain and then applying the camphor, I directly cleaned it with camphor using a cotton pad. Suddenly a new white layer formed at the contact surface between the two layers of substance. The occurrence of a chemical reaction was obvious, and after repeating the experiment in lab conditions, I tried to understand the formation of this new product.

Camphor structure

Rivanol structure 
As far as my chemistry knowledge could tell, camphor is a tricyclic ketone while ethacridine is a heterocyclic compound with two amino groups. Maybe, what happened was an amino-carbonyl condensation with the elimination of one molecule of water, I thought.

But then another question came to my mind. If so, which one of the two amino groups was the one responsible for the reaction? Which one would be more reactive? And last but not least, how would the nitrogen atom influence the occurence of the reaction?

What happened

Well, let's first consider all the possible occurring reactions. There are three main possibilities. One of them, the amino group on the eccentric ring would suffer an amino-carbonyl intermolecular condensation. The second scenario is the amino group on the heterocyclic ring undergoing the same process. Last but no least, the third possibility includes both groups reacting with camphor.

Scenario I

Scenario II

Scenario III

Obvious to me, was the fact that the heterocyclic group was more reactive than the eccentric one for two reasons. One of them is the fact that the inner ring is less aromathic than the outer ones, therefore more reactive.

The second reason involves the electronic effects applicable for the substance, more precisely the static inductive effects for the ethacridine lactate and the π electron displacements in the double bond of camphor.

Electronic effects in camphor

Firstly, we will take camphor. The massive hydrocarbon radical in C₈H₁₄C=O generates a rather strong -I (electron attracting effect) towards the Oxygen atom. This happens due to the fact that Oxygen is more electronegative than Carbon, having a tendency to attract electrons. Due to the same reason, the π bond of the double bond, composed of two electrons is attracted more towards oxygen. Therefore, oxygen develops a  δ- partial charge, while carbon is doing the opposite, accumulating  δ+.

Electronic effects in rivanol

While talking about rivanol, we must take two effects into consideration. One for the left outer ring, and one for the central ring. For the central ring, the positive charge of the Nitrogen atom attracts electrons greatly, therefore, a -I attracting inductive effect is felt by the heterocyclic ring. At the same time, the amino group charges with δ+ making it more electrophilic, thus more reactive.

On the other hand, the outer amino group undergoes the opposite process. The outer phenyl ring, has an aromathic nature, electrophilic by definition. In this case, a very small -I effect is affecting the -NH₂ group, thus accumulating a small δ- partial charge.

Out of the two possible reaction loci, after the previous analysis of the effects in both substances, we can easily draw the conclusion that the locus on the inner ring would be far more plausible for the reaction to occur there, than the other one. In other words, probably, all three reactions occur, but the most probable one would be the one in scenario I as shown below:

The real preponderant reaction

The New Compound

The new compund was a precipitate, initially yellow in appearance, but only due to ethacridin lactate coloration in the test tube.

Before and after the reaction

In fact, after subsequent washing of the precipitate, the yellow coloration faded away almost entirely, what remained being only a very pale yellowish tone of white.

The washed and dried precipitate

After washing and drying, I grounded the precipitate into a very fine powder. Looking under a microscope to the crystals of the compound I found out that they are long, thin and tend to stick together in the form of a stack.

The crystals of the compound viewed in blue light under an optic microscope

Another image of the crystals



In the end, I would like to add a few more images of the compound:

Strepsils - A FLurbiprofen pathway to synthesis

Recently, I caught a cold which is why I took some pills (Strepsils) for sore throat. Curious by nature, I took a glimpse at the chemical composition of the medication. What I observed, was that the active compound in the pills was a substance called Flurbiprofen. Due to the phonetical resemblance to ibuprofen, a well known pain-killer, I made some research about its nature and its uses.

Not surprisingly, it resembles very much to (RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid (more shorter ibuprofen). The difference lays in the substitution of the isoproyl radical with phenyl and the hydrogen atom in ortho with a fluoride atom.

Firstly, I thought of a method to synthethise the compound from phenyl lithium and fluorobenzene as main building blocks, both of which had to be produced from benzene.

Fluorobenzene

Fluorobenzene, was to be obtained by reducing the nitration product of benzene followed by diazotation. The diazonium salt was treated with tetrafluoroboric acid. To obtain the desired compound the reaction product was put to high temperatures.

Phenyl Lithium

The phenyl lithium, is more easily available. All is needed to do in order to produce it is to bromurate benzene in a FeBr₃ environment and after this to react the product with fresh lithium well kept under petrol before the reaction.

The main synthesis

The two building blocks must be first reacted in a moderate to highly acid environment. This way, biphenyl is produced. If directly available, all previous steps may not be taken into consideration, instead the usage of a more pure biphebyl reagent would be preferred.

The biphenyl will then undertake nitration in ortho. This way, when we alkylate with cloroacetic acid, the acetyl radical will be prone to go into the para position. The nitrate is then reduced with an iron and HCl mixture, next following a process similar to that in the innitial synthesis of fluorobenzene.

It is crucially important to reduce the nitro group after the alkylation due to the fact that in the opposite case, the acetyl radical would go into the ortho position yielding a totally different compound. Finally, flurbiprofen is obtained.

Generally, the sore throat medicines are made of an antiseptic and of an antiinflammatory drug. The antiseptic will reduce the microbian flora in the pharynx, while the antiinflammatory will reduce the prostaglandines and thromboxanes production, the root cause of the painful inflammation.

Despite being used for curing sore throat, its uses exceed this limited applicability. Due to the mechanism of action, flurbiprofene makes possible its use for treating the pain involved in different arthritis types of disease, a major relief for the great number of people suffering from a reumatical condition.

A Comparative Study of the Romanian Milk Brands

About a month ago, I participated in a national chemistry contest, ChimeXpert for which I had to make a scientific poster based on my personal observations regarding a certain area of applied chemistry. As a consequence, I tried to find a subject close to my chemical study at school at that given moment, proteins, which is why I have chosen milk as a subject of study.

Purpose

The poster aimed to create an accurate comparative analysis of different Romanian milk brands' quality. The analysis was bound to answer to the need of information amongst the ordinary buyers. The analytical methods consisted in checking the compliance to quality standards of each dairy product selected.

Milk Facts

Milk is a complex liquid used as a food source by young mammals. Chemically speaking, the exact composition of milk varies from species to species, but it generally consists of water, fat, proteins and minerals.

Proteins

Cow milk contains numerous types of proteins (~3.4%), classically divided into two groups:

Globular Proteins: albumins, lyzozime, lactoferin, all playing vital roles in providing immunity for the newly born.
Heteroproteins - Caseins (proteins containing phosphorylated groups)
Caseins are proteins which are made of up to almost 200 amino-acid residues. H₂PO₃^- groups are attached to the serine residues, thus enhancing the reactivity of caseins towards calcium salts.

Caseins from milk come in many different sorts (α_S1 - casein, α_S2 - casein, k - casein, β - casein or λ - casein), all of which present coagulation properties at a pH = 4.6, except k - casein (due to a small number of phosphorylated serine residues in k - casein).

Fats

Raw milk has about 3.5% fats of which butyric acid is the most predominant fatty acid. It has been proved that butyric acid has anticarcinogenic properties, mechanism yet to be understood. Apart from butyric acid, milk also contains linoleic acids, octadecanoic acids and others as well.

Analytical Methods

For doing the study, I used six different brands: Milli, Zuzu, Rarăul, Covalact, Brenac and Tnuva. Two analytical methods have been used. The first one, is a quick but quite unaccurate method for analysing dairy products. It uses a device called LactoScan, based on the interpreting of ultrasonic resonance patterns of the milk being scanned.

Image: Lactoscan.com
The following charasteristics were measured: acidity, fat content, total dry substance (TDS), ash content (SOL), lactose content, proteic content, freezing point (crioscopic point) and density of the samples.

 The coulours indicate the quality of the product:

bad, unsatisfactory, medium, satifactory, optimum

It can be easily noticed that the 6 brands generally comply to the ISO 22000 standard, except Brenac, which has a potential value of 17% added water (so as to reduce acidity of old milk), which is illegal. Moreover, almost all values for Brenac are out of standards.

The second approach to this analysis was the classical method. Through this method, I determined the pH and the acidity (in Torner degrees), the calcium content, and the eventual counterfeiting with NaHCO₃.

Acidity

Acid milk, generally old, is not proper for general consumption due to the excessive lactic acid formed by the Lactobacillus acidophilus in the milk.

CH₃CH(OH)COOH + NaOH → CH₃CH(OH)COO^-Na⁺ + H₂OTherefore the pH of the samples was tested (3 weeks before the expiry date). Normal milk pH is around 6.5. The six samples had a pH varying between 6.17 and 6.58, both values of which are within standards.

Counterfeiting

Generally, milk forgery is done in order to trick the acidity tests. Although illegal, the producers sometimes add NaHCO₃ or starch.

Testing for forgery with baking soda can be done by adding bromthymol blue. A normal milk would stay yellow-orange while a counterfeited one would turn green. All the samples have proven to be counterfeited with NaHCO_3.

When testing for starch, after boiling for two minutes and adding vinegar (to enhance coagulation) and iodine (starch detectiong purpose), the counterfeited tubes should have turned blue (as in the M tube used for demonstration purpose only), all the test-tubes turning out not to have been counterfeited with starch.

Calcium ions detection

Calcium is determined through a rather complex method. First, we have to reduce milk to ashes by heating in an oven at 600^oC for three hours.

The ashes are then incorporated into 50 ml solutions further brought to a pH af about 11.

Then EDTA (Ethylenediaminetetraacetic acid) is titrated into the milk ash solution in the presence of a few drops of murexide. The pink solution will turn purple.

The reaction involved in this mechanism is the following:

The calcium levels measured were at normal levels 800-1300 mg/L.

Conclusions

All the brands were more or less within standards, except Brenac, where severe disconcordances have been noticed. The best quality milk has turned out to be Covalact, respecting virtually all issues stipulated in standard with the exception of baking soda counterfeiting.

Outcome

At the contest, I have won the best poster award and a special award from the Romanian Inventors Forum.

Finally, you can find the poster here, in the version presented by me at the contest.

BizCamp 2010 - Day 1

I am writing to share with you the experience I lived in the last two days, BizCamp 2010, a business camp for students. Here, through a series of workshops and sessions on the topics of success and how to achieve it, how to set goals, how to follow your dreams and many other personal development skills, I have met a whole bunch of extraordinary people and it was an incredible experience, really helpful for me.

Day 1

Day one was focused generally on the idea of reaching success. There were many speakers, each of them with a creative but very different style from the others. Among the ones who presented there was Alina Constantinescu, who talked about the importance of social media in gaining success and Mihail Musat who had some outstanding performances when being in front of the public.

She stated three principles that can lead to a success also determined by the personal network of relationships with the others. These principles are FIND OUT (be aware of the existing opportunities that surround you), CHECK OUT (show interest towards the others, create your network) and WORK OUT (get involved and be proactive).

Beside these steps, there were also some ideas that were outlined throughout the entire presentation:

• Precaution can be dangerous when it doesn't make room for new opportunities.
• When you start something new, begin with whatever you have and improve it later on in the process of building it.
• The worst thing that may happen to you is not the lack of success, but the lack of anything happening to you.

Then, Mihail Musat, the founder of LumeBuna.ro tried to send us the message that success is a relative term. Therefore, my definition of success may be totally different from yours and so on. Interpreted in another way, even failure may be a means of succeeding due to the fact that we all should learn from our mistakes.

Through some simple examples and stories from his own experience, he succeeded (of course from my point of view due to the relativity of the term :D ) in getting across some simple but important ideas:

• Never be impeded by your own thoughts. Never try finding reasons for a thing I want to do but for a particular reason it is "not recommended".
• What will I choose? A potential failure or the lack of a potential success? (no pain, no gain)
• It is much more important to know what I DO want than what I DON'T want.
• Do things that you are passionate about.
• "Experience is not what happens to a man but what a man does with what happens to him" (make proper use of your personal experience)

After that, there came a series of workshops that emphasized the importance of a mix between passion, work and creativity in your way to success, three elements that make a difference.

There were also some funny parts of the day, like when we were the first in our country to see the new Coca Cola cold season commercial :)



In the end it turned out to have fulfilled our expectations and it was definitelly a really nice thing to take part in.

Coming next - BizCamp 2010 Day 2 :D

Barbeque Chemistry

Hello there! It's me again with a pretty unusual subject for this rather cold period of the year: barbeque chemistry. Why? Because it reminds us of the hot summer weekends when we attend outdoor barbeques and because I have read an interesting science paper regarding barbeque fuel tablets.

When we go out and make a camp fire we might use the traditional method of matches and wood or if we are more lazy, we could use those camp fire lighters such as liquid petrol or solid fuels for rapidly starting up a fire. Some are based on phosphorus while others rely on an organic compound, hexamethylentetramine, also called hexamine or urotropine and this is the compound I am going to talk in the next few lines.

Urotropine has a spatial structure, having the form of adamantane, the simplest diamondoid with the only difference that the four methine groups are replaced by nitrogen atoms. Therefore, the structure is the following.

Industrially it is synthesized from methane oxidized in air at 400 to 600 ^oC on nitrogen oxides so as to obtain formaldehyde. Four molecules of formaldehyde react afterward with six molecules of ammonia and urotropine is the result. The conditions under which the reaction occurs are temperatures high enough so as the formaldehyde and the ammonia to be in gaseous form.

The possible mechanism for this reaction might involve three steps. The first one would be an addition of NH3 to the formaldehyde. Therefore, NH2-CH2-OH is obtained. After this, the compound eliminates water and the aldimine CH2=NH is formed. Through trimerisation a cyclic compound is formed and further reacted with 3 molecules of formaldehyde and one molecule of NH3 will finally make urotropine.

The urotropine synthesized this way is the major product in the solid fuel tablets. They have the advantage of burning on any type of weather with a rather hot flame at about 760 ^oC. Moreover, these tables do not give off fumes due to the fact that the only gases released are CO2, N2 and vapors of water: (CH₂)₆N₄ + 9 O₂ → 6 CO₂ + 2 N₂ + 6 H₂O.

Image from: http://www.ebit.de/

It is important to mention that urotropine is used also to treat urinary infections due to its activation by the acids in urine but also as a precursor to many explosives such as HMTD, a compound suspected to have been used in the London underground terrorist attacks in 2005.

All in all, it's highly useful but it can turn out to lead to dangerous products so it is important to be used with care.

Colorant Synthesis

Hello there once again! I have recently started a new chapter in my preparation for the Chemistry Olympiad, the azo compounds, very important for the production of azo colorants, mainly used as food colorants but also as dyes and other kinds of pigments. I was solving some synthesis problems until I got stuck at the synthesis of Naphtol Blue Black (structure shown below) from inorganic and organic substances with no more than two carbon atoms.

From the very beginning it was clear to me that I first had to make the naphthalene ring. Therefore I started from acetylene and made the necessary trimerisation in order to obtain benzene. Next, I used a Friedel- Crafts alkylation and obtained o-diethylbenzene, which through severe dehydrogenation at 400-600 ^oC yields naphthalene.

It is important now to arrive at the H-Acid structure, also called 1-Amino-8- Naphthol-3,6-Disulfonic Acid. In its synthesis it is vital to leave the formation of the amino group at the end so as not to be involved in any unwanted reaction made possible by the increased sensitivity of amines.

In its formation, firstly the naphthalene is nitrated and then trisulphonated. The third acid sulphite group in the α position is used for creating the -OH group through a process known as alkaline melting. The rest of the groups do not undergo this process because they are in less reactive β positions. Nevertheless, the other -SO3H groups suffer neutralization with NaOH and form ionic bonds between oxygen and sodium, thus replacing the hydrogen atom.

Finally the -NO2 group is reduced on iron and hydrochloric acid using 6 [H], produced by the following reactions:

Fe = Fe ³⁺ + 3 e^-

HCl = H⁺ + Cl^-
H⁺ + e^- = [H]

The H-acid is ready. Now comes the tricky part where I got stuck. You now have to do the coupling, but there is the problem of the lack of symmetry within the compound.

The preparing method for the diazonium salts to be used in the coupling reaction. Firstly a nitration followed by reduction on Fe/HCl and then diazotation with NaNO2 and HCl after the reaction:

Ar-NH2 + NaNO2 + 2HCl = Ar-N⁺≡N]Cl^- + NaCl + 2 H2O

If you couple in normal conditions a diazonium salt to our naphthalenic ring there will be two problems. First, it won't couple into the β position, α being definitely preferred by the reaction itself. Second, even if you succeed in coupling a diazonium salt into the β position, it will immediately occupy both β carbons.

But there is one thing that makes the H-Acid so suitable for this multiple coupling. On one of the rings in the naphtalenic cycle, we have phenolic -OH, while on the other we have an amino group -NH2. We can clearly see the difference, one is moderately alkaline while the other is acid.

This does matter because in the coupling we have to choose between acidic or alkaline environment. Therefore, the coupling near the alkaline -NH2 group will take place in acidic conditions whereas the coupling next to the phenolic -OH in an alkaline environment.

The first coupling in acidic conditions

The second coupling in NaOH environment and the final product

A sample of the colorant. Image from http://www.biomed.cas.cz/

Finally, the synthesis is done and we have our Naphtol Blue Black colorant. I considered this useful enough to be posted due to this special property of the H-Acid dictated by the presence of the two different groups that influence drastically the course of the reaction and because it is quite complex enough to bring in front an element of challenge. I'll also try to make it in the lab although I'm not sure I will succeed, being a quite difficult synthesis. See you next time!

Ask a Nobel Laureate and You Have a Good Chance to Receive an Answer

Hello everybody! Last month I was surprised to see an email in my inbox from Rieko Kawabata, Programme Coordinator at Nobelprize.org inviting me to take part into the Ask a Nobel Laureate project, by asking a chemistry question to Professor Harry Kroto, Nobel laureate in 1996 for the discovery of fullerenes. From all the questions submitted a few were to be answered by Prof. Kroto himself. Therefore, I submitted two questions to Professor Kroto.
Two days ago, while searching for the answered questions, I found to my great surprise and happyness that both my questions have been answered, and I am transcripting his answers so as for you to have his answers also in text format. :)

Question 1



A: "Andrei Florea, two questions, question 12a:"
Q: "The mechanism for creating fullerenes is not yet fully understood. What would be the most likely explanation for that formation?"
A: "Well, it's pretty complicated, but it's quite clear that carbon is one of the fastest nucleating compounds, atoms or elements that we have and it zipps up to thousands very quickly from hot plasma and carbon molecules and graphites, these are down to actually melt, in fact no one seen liquid graphite to my knowledge, or liquid diamond... but I think what happens is from carbon atom plasma that we produce with a laser and we vaporize graphite, carbon chains first form, I think, liniar carbon, liniarish carbon C1, C2, C3, C4, C5, C6, so on; and my colleague David Walton really had a briliant way of making carbon chain molecules with just things on the end, so it was quite clear that you can make carbon chains of 30 or more carbon atoms. My guess is, what is happening in the range when they get to a 18, 19, 20, other things are forming and we think that there are also monocyclic rings forming in which the chain turns into a bead chain, you know... a ring carbon atoms in a monocyclic ring. I think that's now been proven by some really neat science by John Meyers Group in Basel and it was conjectured many years ago by theoreticians; then at around 20 to 30 to 40 to 50, I think these coalesce into cages and these cages may and we're pretty sure, we've got some results here a student pulled on working with myself and we showed that there are definitely spiecies with 28 carbon atoms which are cages, these circumstantial but nevertheless pretty definite cage structure. So at that point you've got your little baloons, if you wish. I think what happens then is carbon atoms and carbon molecules coalesce into this... ingested into this network of C40, C50 and so on and when they hit C60, they hit the first stable structure. C60 is the first stable fullerene. So a lot get locked into that, some get shooting on to C70 and others to higher ones. As you get these and you extract them, 10% of the soot, which are large particles, are in the form of fullerenes, sort of like, 80% to 90% C60, about 10% C70 and a few percent all the others with more and more carbon atoms and of course nanotubes and many other things. So, basically, I think that you have this cage forming at small levels and all others are being ingested into this structure and they stop when they get to C60 and that's why C60 is strong. And I think that's about as far as I'm prepared to go; it's just very, very complicated. Now people have been looking at the combustion process for 50 years, theorising and doing experiments. And they missed C60, so not sure they got it right, I don't know... it's very complicated and I think the best theory is my... theory; it all comes together. Best I can do."

Question 2



Q: "It has been proven that when chloroform is added to fullerenes, their structure changes from a cubic network of buckyballs to a hexagonal one, a process with impact on superconductivity. Why does this structural change occur?"
A: "Well, I don't know... I think the difference between hexagonal and cubic packing is a very, very low energy barrier, or a very small difference in barrier, so the impact of an intercalated molecule will be quite strong and the intermolecular forces will favour in the case of the chloroform structure, the hexagonal one."

In the end, I would like to thank Professor Harry Kroto and the nobelprize.org team for this incredible opportunity that I've been given and to invite you all to Ask a Nobel Laureate. :D

Surgery through the eyes of a teenager - Day 6

Day six, simply awesome! We spent all day in the intervention I was telling you about in the last post, with Dr. Halpern and three colleagues of him trying to fix the aortic aneurysm rupture in the patient. In the evening we were exhausted from staying on two feet for about eleven hours, but we were all happy that the intervention seemed to be a success.

When we got into the operation room, the patient was already laying on the table, prepared for the anesthesia. He received both spinal block and general anesthesia, the general one being for not feeling anything during the intervention and the spinal one for relieving the possible postoperative pains. The patient was quite cooperative and the anesthetist put him to sleep in almost no time, thus allowing Dr. Halpern to place the patient in a comfortable position for the surgeons to operate properly.

After having this done, Dr. Halpern, assisted by another colleague, started performing the whole procedure. Firstly, an incision would be done somewhere near the patient's shoulder so as to expose the axillary artery.

He had to cut through a superficial layer of subcutaneous fat and after that, through the proximal end of the pectoralis minor muscle so as to reach the artery. Once the artery reached, the team anastomosed (attached) a polytetrafluoroethylene (PTFE) prosthetic graft to the artery. This was done with the use of a very thin thread of polypropylene wire, similar to the one we had used for performing the fistula intervention in the first day.

The surgeons consequently attached to the graft a device called visceral perfusion system (octopus), basically a device which split the blood supply into four, one for each of the four major abdominal arteries that would have been left short of blood supply when they clamped the aorta so as to remove the aneurysm. The device was composed of different cannulae, all plugged one to another in a tree-like configuration.

Here was the first cannula inserted into the PTFE graft

Then, the surgeons opened the patient's thorax between two ribs, by cutting through intercostal muscles. Using a special device, they enlarged the space between the ribs. At that stage we could clearly see the lungs with some pretty black odd spots covering them (maybe due to smoking?). We could even make out the heart beating at pretty high rates and the anesthetist could even read on the ECG scan some abnormal extrasystoles when touching the heart with the hands or with surgical instruments.

You can clearly see the left lung of our patient in this picture

In this 5 seconds video that I've made, you can distinguish the beating heart in the open thorax of the patient

After this, Dr. Halpern cut the patient's abdomen and one rib into half so that he could have easier acces to the aorta, introduced the octopus into its place in the four major arteries, one branch of the device per artery and finally clamped the aorta at the thorax level. Thus, the blood could pass from the heart to the viscera through this external "piping system" and not suffer from no blood supply while the aorta was clamped.

Here, the four plastic tubes are the branches of the visceral perfusion

Consequently, the team put another synthetic tube so as to replace the aorta, united the celiac artery, and the renal arteries were anastomosed together at the distal end of the prosthetic graft, while the superior mesenteric artery was attached to a smaller graft anastomosed at its turn, right into the middle of the prosthesis, used to replace the piece of aorta suffering from aneurysm.

Immediately after that, the surgeons started putting back in place the lungs, sewing back the ribs and suturing the wounds.

You can see the rib and the doctors' hands sewing it together

Finally, blood draining tubes were inserted into the patient's leg so as to collect any possible blood from postoperative hemorrhages. The axillary prosthesis was removed and the artery closed, in this way finishing the operation.

Nevertheless, the most amazing thing I noticed, what not on the 6th day I'm talking about in this post, but this morning (the 7th day), when Dr. Halpern came in and told me that last night he had an emergency, and had to operate from midnight until 7 AM another aneurysm, infrarenal this time, which is an operation as big as the one described here. So more than 20 hours of almost continuous work requires a lot of resilience from the surgeon and an ability to focus day and night without break.

This was the last day of "Surgery through the eyes of a teenager" series and I hope you enjoyed this fantastic opportunity of peeking through into the surgical world.

To sum up, it was an incredible experience and I believe it strengthened my resolve to follow the path of medicine. I would also like to thank Dr. Halpern once again for taking the responsibility of my being there and I also invite you to say your opinion regarding this 6 days experience of mine. See you soon!