Why do some plants die at the very first frost, while others calmly endure the Yakutian winter with temperatures dropping below minus fifty? The answer lies in ordinary water — or rather, in how remarkably different it can be inside living plant cells and tissues. Scientists distinguish two fractions of water in plant tissues: free and bound. Free water behaves just as we expect: at zero degrees Celsius it turns into ice, and the resulting crystals rupture delicate cell membranes from within. Bound water, on the other hand, is tightly held by proteins, sugars, and starch molecules and does not freeze even at minus twenty degrees or lower. This "unfreezable" fraction acts as a natural antifreeze and largely determines whether a plant will survive a sudden cold snap or not.

But how can we measure exactly how much bound water is present in a birch leaf or a lingonberry twig? In well-equipped laboratories, researchers use a differential scanning calorimeter (DSC) — an instrument that detects the tiny amounts of heat released during freezing and can thereby separate free water from bound water. The problem is that such a device costs a fortune and is completely inaccessible for a school laboratory.

In our project, we propose a different path: to build such a calorimeter ourselves, using affordable and widely available components. The heart of the device will be an Arduino board, while high-precision TMP117 digital temperature sensors, capable of detecting temperature changes as small as one-tenth of a degree Celsius, will serve as its accurate electronic "eyes." We will cool our samples using Peltier elements — the same ones found in portable car refrigerators — or possibly an ordinary freezer. Project participants will assemble the electronic circuit with their own hands, write a sketch to simultaneously poll several sensors, build a thermostatted measurement block, and calibrate the instrument using pure water.

During the experiment, the sensors will continuously record the temperature, and right before our eyes the laptop screen will begin to display thermograms — graphs on which the freezing of free water appears as a characteristic crystallization (freezing) peak. This peak holds the key information: its area is proportional to the amount of heat released during ice formation, and therefore to the mass of free water in the sample. Bound water, in this temperature range, remains liquid and produces no signal at all. We will determine the total water content by drying the samples and measuring both fresh and dry weight. By comparing the results for different species and different plant organs, we will try to answer the question: which plants are better prepared for sudden frosts, and why? Perhaps lingonberry will prove to have more bound water than plantain, or roots will differ from leaves.

Requirements for participants:
This project is for anyone who's not just into listening, but wants to get their hands busy and see how things actually work—right away. Into electronics and soldering? You'll be assembling the circuit and tuning the sensors. More of a programming fan? You'll write the Arduino code. Love biology and hiking in the woods? You'll take the lead on collecting plants and making sense of the results. And if numbers, graphs, and spotting patterns are your thing—you'll be analyzing thermograms and calculating just how much water froze.
Working together as a team, we'll build a real scientific instrument, gather brand-new data about Yakutia's plants, and figure out how they gear up for the harshest winter on Earth. Come join us!