parkhanyoonjae

Latest Posts by parkhanyoonjae

The way I’ve loved you was everything and nothing at the same time.

— Roland Barthes, A Lover's Discourse; Fragments [translated by Richard Howard]

“Don’t give up. All of your hard work will pay off soon, stick with what you’re doing no matter how hard it gets.”

— Unknown

to be seen without performing. to be heard without screaming. to be missed without disappearing. to be enough without proving it. to be held without falling apart. to be understood without explaining. to be wanted without conditions. to be. to be.

— v, from “the gravity poem” (via letsbelonelytogetherr)

I don’t want anything from you... I just want you.

I love you so much, my dearest

Take care always, my favorite person.

“Letters Never Sent”

In flickering light of an oil lamp’s glow,

A boy bends low with ink to sow

The trembling truth he’s never said—

A name, a thought, a heart he bled.

“Dear Lillian,” begins the page,

Penned with hands not yet of age.

His breath held tight, his pulse a thread,

Words unsent, but fully meant.

By the mailbox in the rain,

He stands alone with hope and strain.

Will it reach? Will she reply?

Or will it fade before goodbye?

But footsteps break the quiet night,

She stands beneath the softened light.

She sees the note, she meets his eyes—

No thunder, only small surprise.

She reads, she smiles—no words are said,

But silence glows where fear had bled.

He sees his world within her glance,

And knows he’s had his one true chance.

The years unfold like folded notes,

Soft creases pressed through all he wrote.

They meet again, and once again,

Beside the box where love began.

A letter passed through wrinkled hands,

A bench, a smile, the same old stand.

He reads alone, though not unblessed—

For some replies live in the chest.

Now rain falls soft on rusted blue,

Where children stop and read it too.

And etched in brass beneath the light:

“May all love letters find their flight.”

You all know my love for afternoon study sessions

13 March 2025

The crystallochem situation is absolutely insane. I sign up for this class even though I really truly don't want to bc I know how ridiculously hard it's going to be. I only do it bc my thesis supervisor wants me to do it. The class turns out to be even harder than I thought it would be and the professor turns out to be an awful teacher. The first test starts to approach and I'm so terrified it makes me cry and gives me nervous headaches. I've never failed a test and now I seriously begin to worry this one will be the first one, but I still work my butt off studying for it. The test comes, then the results. Over half the group fails. I score 87% and the only person who gets a better score is preparing for an olympiad in crystallography. Absolutely bonkers.

When I tell you crystallo is the most difficult class I've ever taken, I mean it. But now I feel powerful and unstoppable. I got a huge confidence boost! I took myself to my favorite wrap place as a means of celebrating :) 🌯

[research life]

A Friday spent writing + reading 🩵📝📚

Andrei Tarkovsky, from a diary entry featured in Time Within Time; Selected Diaries

Just go for it ⚡

Real-Life Uses of Calculus

Calculus isn’t just an abstract, ivory tower concept relegated to textbooks—it’s a powerful tool woven deeply into the fabric of our daily lives, from the precision of medical dosage to the unpredictability of the stock market.

1. Medicine: Optimizing Drug Dosage

Calculus plays a key role in pharmacokinetics, the branch of science that deals with the absorption, distribution, metabolism, and excretion of drugs in the body. When doctors prescribe medication, they need to ensure that drug levels remain within therapeutic bounds, not too high to cause toxicity and not too low to be ineffective. This is where differential equations, a core part of calculus, come into play. The rate of change of drug concentration over time is modeled with calculus to determine optimal dosage and scheduling for sustained, effective drug levels.

Take antibiotics, for example: they must be administered at specific intervals to maintain an effective concentration in the bloodstream while preventing bacterial resistance. Calculus allows for the continuous monitoring of drug levels and the adjustment of dosages based on individual metabolism rates, ensuring maximum therapeutic benefit.

2. Physics and Engineering: Motion and Forces

In classical mechanics, calculus is used to describe motion. Newton's laws of motion and universal gravitation are based on derivatives and integrals, the foundational elements of calculus. The change in velocity (acceleration) is the derivative of position with respect to time, while the area under the velocity-time graph gives us the distance traveled.

For instance, when designing cars, engineers use calculus to model the forces acting on the vehicle, such as friction, air resistance, and engine power. Calculus helps optimize everything from fuel efficiency to safety features, ensuring that a car can handle various conditions without exceeding performance thresholds.

3. Economics and Finance: Predicting Stock Market Trends

In economics, calculus is used to understand and predict market behavior. The concept of marginal analysis—examining the effects of small changes in variables—relies heavily on calculus. For example, marginal cost is the derivative of total cost with respect to quantity, and marginal revenue is the derivative of total revenue with respect to the quantity of goods sold.

In the stock market, calculus is utilized in quantitative finance to model stock prices using stochastic differential equations. Techniques like Black-Scholes for options pricing rely on calculus to determine the fair price of financial derivatives by analyzing how small fluctuations in stock prices impact their expected value. The concept of risk management—how much risk is worth taking for a given return—also uses derivatives to evaluate the rate of change of potential outcomes over time.

4. Environmental Science: Climate Modeling

Climate change models are inherently tied to calculus. Calculus is used to model the flow of energy through the Earth's atmosphere, oceans, and land, and how this energy affects global temperatures. The change in temperature over time is governed by differential equations, accounting for factors like greenhouse gas emissions, solar radiation, and ocean currents. As a result, climate scientists use calculus to predict future climate scenarios under various emission levels, helping inform policy decisions on global warming and sustainability.

5. Computer Science and Machine Learning: Optimization Algorithms

In machine learning, algorithms are designed to optimize a given function—whether it's minimizing the error in predictions or maximizing efficiency in a task. These algorithms often rely on derivatives to find the minimum or maximum of a function. For example, gradient descent, a popular optimization algorithm, uses the derivative of a function to iteratively adjust parameters and reach the optimal solution.

In computer graphics, calculus is essential for creating smooth curves and realistic animations. The mathematical process of curvature, which is the rate of change of direction along a curve, is vital for rendering images in 3D modeling and augmented reality.

6. Astronomy and Space Exploration: Orbital Mechanics

In space travel, calculus is crucial in calculating orbits, trajectories, and spaceship velocity. The path a spacecraft takes through space is influenced by gravitational forces, which can be modeled using calculus. For example, NASA’s mission to Mars relied on calculus to calculate the optimal launch window by accounting for the positions and motions of both Earth and Mars, ensuring the spacecraft would reach its destination efficiently.

Salt formation: an effective means to improve the physical and chemical properties of drug molecules and enhance the druggability of drugs

In drug development, drug forming research, including pharmacodynamics, pharmacokinetics, and early safety evaluation of drugs, is required to determine whether the active compound has the potential to be developed into a pill. The drug-forming properties of drugs are also an essential part of the drug-forming evaluation, and salt formation is one of the effective means to improve the physicochemical properties of drug molecules and enhance drug-forming properties.

Many drugs are salts of organic acids or bases. The salt formation can make some oily organic acids or organic bases solid, which is conducive to preparing concrete dosage forms. Moreover, the salt formation of drugs increases the water solubility, which is conducive to preparing some aqueous dosage forms, such as water injection and oral liquid. The salt formation process is often a purification process, which removes the impurities mixed in the drug that cannot become salt, etc. So what are the benefits of salt formation in drug development studies?

1,Salt formation of drugs can change the solubility of drugs and improve drug-forming properties

The solubility of drugs affects their pharmacokinetic properties, chemical stability, and the choice of dosage form, which is an essential element in evaluating drug-forming properties. A salt formation can change the solubility of drugs and improve the water solubility of drugs through salt formation, which is the primary method to develop intravenous injections of drugs, such as the poor water solubility of diuretic etanercept, which is mainly available in tablet form.

Still, its sodium salt has better water solubility and can be used to prepare intravenous injections. The free base of the antipsychotic haloperidol is also marketed mainly as a tablet due to its low solubility. At the same time, its lactate can be used to prepare injectable solutions with improved solubility.

Sometimes it is necessary to prepare extended-release dosage forms by reducing the solubility of the drug. In this case, it is required to form a salt of the drug with an acid or base of higher relative molecular mass and hydrophobicity. For example, the commercially available dosage forms of antidepressant trazodone hydrochloride are tablets, oral solutions, etc. The study of trazodone in salt found that its p-toluenesulfonate and dihydroxynaphthalate are much less soluble in water than sulfate, and hydrochloride p-toluenesulfonate is more suitable for the preparation of slow-release oral formulation.

2,Salt formation can improve drug stability

Formulation evaluation also needs to rely more on data generated from pre-prescription research work, such as extreme pH, high temperature, freeze-thaw, light, forced oxidation, and other forced degradation experiments to understand the stability of drugs. Medicilon offers a full suite of chemical drug development services integrated from start to finish. We provide a one-stop service through pre-prescription studies, drug analysis, drug stability studies, formulation development, and complete CMC services.

The stability of the drug is directly related to its dosage form and the selection of production and packaging conditions, and it even affects the effect of the final preparation. Some researchers chose the insoluble phenazopyridine (PAP) as a model drug and improved the solubility and stability of phenazopyridine through drug co-crystals and salts.

The marketed product of phenazopyridine is phenazopyridine hydrochloride. Still, the peak plasma concentration in rats is only 10-20 ng after 200 mg dose administration, and it is for these reasons that the clinical application of PAP is limited. Therefore, the investigators prepared one eutectic formed by phenazopyridine with phthalimide (1) and two salts with 4-hydroxyphenyl acetic acid (2) and saccharin (3) by solution method and spiked grinding method, respectively, and their structures obtained by X-ray single crystal diffraction showed the presence of hydrogen bonding between phenazopyridine and all three eutectic ligands, collectively called hydrogen bonding complexes [1].

X-ray powder diffraction, DSC, and IR characterized it. The powder solubility of the three hydrogen-bonded complexes was measured, and the hygroscopicity of the solid powders was examined at 85% and 98% relative humidity for 1, 3, 5, 7, 10, 14, 21, and 28 days. The experimental results showed that the melting points of the three hydrogen-bonded complexes were all between phenazopyridine and eutectic ligands; the powder solubility of 1-3 was 10, 7.5, and 2 times that of PAP, respectively; the hygroscopicity was much lower than that of PAP and its hydrochloride under the conditions of 85% and 98% relative humidity. According to the above results, it is clear that 1-3 has a good prospect for improving the bioavailability and stability of phenazopyridine.

3,Salt formation can change drug compliance

Drug formulation should be safe, effective, stable, and easy for patients to accept, i.e., good compliance. An essential indicator of compliance with oral formulations is the acceptability of taste, which is particularly important when the drug is administered in liquid, chewable, or effervescent dosage forms. For example, the prerequisite for oral drugs to produce a taste response must first be dissolved in the mouth or taken in solution. Therefore, one of the ways to reduce the bitterness of orally administered drugs is to make them into poorly soluble salts and to make their saturated concentration below the threshold for producing taste sensation.

4,Into salt, can extend the patent protection of the drug or circumvent its patent protection

In the R&D process of new drugs, once an active compound is discovered, it is generally applied for a patent on its chemical structure to ensure the novelty of the patent. After the drug is marketed, the developer will further develop its derivatives, such as making salts or changing the crystal form and dosage form, and file subsequent patent applications to obtain the longest possible patent protection period. Nowadays, most new drugs marketed internationally use this type of patent protection.

In addition, drug salting can reduce adverse effects. In developing salt-forming drugs, the key is to select the acid or base with which the drug is salted. The selection of the acid or base should consider its pKa value and safety, as well as the route of administration and dosage form after salting. In conclusion, drug-forming studies and drug-forming evaluations can be conducted to determine the drug-forming properties of drugs better and improve the efficiency of new drug development.

[1] Improvement of solubility and stability of phenazopyridine by drug eutectic and salt [J]

☕14.06.2022 // I almost finished pharmacokinetics today! I also did some exercices because my finals are in a week, I'm starting to feel stressed out but it's ok 🩵

I was reaaaaally tired so i took it slow, and i need to learn how to do coffee without a coffee machine if I want to survive the following days haha

🎧 Enfance 80 - Videoclub

The popular enzyme inhibitor at its finest

Doctor: What did you learn today?

Student: That you should never have meds with grapefruit juice.

Always go too far, because that's where you'll find the truth

- Albert Camus

I miss your natural scent :(((

let me be your perfume

I wanted to write down exactly what I felt, but somehow the paper stayed empty, and I couldn't have described it any better.

Photography 14/n 📷

at the house

10 March 2025

I got the mug as a gift from my classmate. I wasn't able to attend the Christening of her daughter last Saturday due to sudden emergency. I like the mug actually, I used it as my container for my coffee.

University Diaries:

The Manuscript (Revisions)

9-11 March 2025

Here we are again, pulling an all-nighter at the moment for the revisions of the paper focusing on the new methodology of the study to be conducted experimentally. I read several papers, regarding the new method to be used due to unavailability of the apparatus (for the previous method) in the testing facility, while at my part-time job and in the bus 2 days ago. I have to write the procedure based on how it was written in most researches and not by stepwise procedure. I got to appreciate the essentials of research wholeheartedly in which I am eager to pursue higher studies after finishing the bachelor's degree. Let's have coffee, guys!

University Diaries: Friday Sunset

March 7, 2025

Our prelim exam in Review in Professional Subjects 2 covering Module 4 (Biopharmaceutics & Pharmacokinetics, Pharmacology, and Toxicology) was now officially done. I was on my way to the bus stop when I caught a glimpse of sunset as I looked behind. I decided to capture this image signifying the success of my hardwork in taking the pre-board exam.

From February 16 to 17, 1913 Letters to Felice by Franz Kafka First published : 1973

i am 100% sold on this already