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Comment by Dr. Krishna Kumari Challa on January 18, 2024 at 9:12am

The researchers employed a sophisticated experimental setup to observe and quantify the dynamics of microscopic systems undergoing thermal relaxation. At the heart of their experimentation were optical tweezers—a powerful technique using laser light to capture single microparticles made of silica or plastic.

"These tiny objects move in an apparently random fashion due to the collisions with water molecules, executing the so-called Brownian motion while they are confined to a small region by tweezers. The higher the temperature of the water, the more intense the Brownian motion will be due to more frequent and intense collisions with water molecules.

To induce thermal changes, the researchers subjected the confined microparticles to varying temperatures. They carefully controlled the temperature of the surrounding environment using a noisy electrical signal, simulating a thermal bath.

This experimental device allows the physicists to track the motion of the particle with exquisite precision, giving access to these previously unexplored dynamics.

By manipulating the temperature and observing the resulting movements, the team gathered crucial data to understand the intricacies of heating and cooling at the microscale level.

The development of the theoretical framework (thermal kinematics) played a pivotal role in explaining the observed phenomena. This framework combined principles from stochastic thermodynamics—a generalization of classical thermodynamics to individual stochastic trajectories—with information geometry.

Thermal kinematics provided a quantitative means to elucidate the observed asymmetry between heating and cooling processes. This allowed the researchers not only to validate theoretical predictions but also to explore the dynamics between any two temperatures, revealing a consistent pattern of heating being faster than cooling.

M. Ibáñez et al, Heating and cooling are fundamentally asymmetric and evolve along distinct pathways, Nature Physics (2024). DOI: 10.1038/s41567-023-02269-z

Part 3

Comment by Dr. Krishna Kumari Challa on January 18, 2024 at 9:09am

At the microscopic level, heating and cooling are processes involving the exchange and redistribution of energy among individual particles within a system.

In heating, energy is injected into each particle of a system, leading to an intensification of the particles' motion. This causes them to move more vigorously. The higher the temperature, the more intense the Brownian (or random) motion of these particles due to increased collisions with surrounding water molecules.

On the other hand, cooling at the microscopic level involves the release of energy from individual particles, resulting in a dampening of their motion. This process corresponds to the system losing energy, leading to a decrease in the intensity of particle movement.

Researchers took an object from a boiling-water bath (at 100 degrees Celsius) and immersing it in a mixture of water and ice (at 0 degrees Celsius)."

They compared how fast the system equilibrates with the reverse protocol when the object is initially in the cold bath and heated in boiling water. They observed that, at the microscale, heating is faster than cooling, and they explained this theoretically by developing a new framework they call thermal kinematics.

Part 2

Comment by Dr. Krishna Kumari Challa on January 18, 2024 at 9:06am

Scientists report fundamental asymmetry between heating and cooling

A new study  by scientists has found a fundamental asymmetry showing that heating is consistently faster than cooling, challenging conventional expectations and introducing the concept of "thermal kinematics" to explain this phenomenon. The findings are published in Nature Physics.

Traditionally, heating and cooling, fundamental processes in thermodynamics, have been perceived as symmetric, following similar pathways.

On a microscopic level, heating involves injecting energy into individual particles, intensifying their motion. On the other hand, cooling entails the release of energy, dampening their motion. However, one question has always remained: Why is heating more efficient than cooling?

To answer this questions, researchers have introduced a new framework: thermal kinematics.

Part 1

Comment by Dr. Krishna Kumari Challa on January 17, 2024 at 7:02am

Soldering wounds with light and nano thermometers

Not every wound can be closed with needle and thread. Researchers have now developed a soldering process with nanoparticles that gently fuses tissue. The soldering technique is expected to prevent wound healing disorders and life-threatening complications from leaking sutures.

Some time more than 5,000 years ago, humankind came up with the idea of suturing a wound with a needle and thread. Since then, this surgical principle has not changed much: Depending on the fingertip feeling of the person performing the operation and the equipment, cuts or tears in the tissue can be joined together more or less perfectly. Once both sides of a wound are neatly fixed to each other, the body can begin to close the tissue gap permanently in a natural way.

However, the suture does not always achieve what it is supposed to. In very soft tissues, the thread can cut through the tissue and cause additional injury. And if the wound closure does not seal on internal organs, permeable sutures can pose a life-threatening problem. Researchers have now found a way to solder wounds using lasers.

Soldering usually involves joining materials together by means of heat via a melting bonding agent. The fact that this thermal reaction must remain within narrow limits for biological materials and at the same time the temperature is difficult to measure in a non-invasive way has been a problem for the application of soldering processes in medicine.

The researchers tinkered with a smart wound closure system in which laser soldering can be controlled gently and efficiently. For this purpose, they developed a bonding agent with metallic and ceramic nanoparticles and used nanothermometry to control the temperature.

The elegance of the new soldering process is also based on the interaction of the two types of nanoparticles in the bonding protein-gelatin paste. While the paste is irradiated by laser, titanium nitride nanoparticles convert the light into heat. The specially synthesized bismuth vanadate particles in the paste, on the other hand, act as tiny fluorescent nano thermometers. They emit light of a specific wavelength in a temperature-dependent manner, allowing extremely precise temperature regulation in real time.

This makes the method particularly suitable for use in minimally invasive surgery, as it does not require stirring and determines temperature differences with extremely fine spatial resolution in superficial and deep wounds.

The researchers also succeeded in replacing the laser light source with gentler infrared (IR) light. This brings the soldering technology another step closer to be used in hospitals.

Oscar Cipolato et al, Nanothermometry‐Enabled Intelligent Laser Tissue Soldering, Small Methods (2023). DOI: 10.1002/smtd.202300693

Comment by Dr. Krishna Kumari Challa on January 17, 2024 at 6:57am

Energy-starved breast cancer cells consume their surroundings for fuel, research suggests

Breast cancer cells ingest and consume the matrix surrounding them to overcome starvation, according to a new study published January 16 in the open access journal PLOS Biology. The finding elucidates a previously unknown mechanism of cancer cell survival, and may offer a new target for therapy development.

Cells in the breast, including tumor cells, are embedded in a meshwork called the extracellular matrix (ECM). Nutrients are scarce in the ECM, due to limited blood flow, and become even scarcer as tumor cells grow. And yet they continue to grow, leading the authors to investigate how tumor cells supply themselves with the raw materials to support that growth. To do so, they seeded breast adenocarcinoma cells into either collagen (a major component of the ECM) or a commercial matrix preparation, or onto plastic, with or without certain critical amino acids. Without those amino acids, cells on plastic fared poorly compared to those in one or the other matrix. Similar results were seen with other matrix models—the tumor cells were able to overcome the reduction of amino acids when surrounded by matrix. Next, by fluorescently labeling the collagen and watching its journey through the cell, the authors showed that the cells took up ECM and broke it down in digestive compartments called lysosomes; when the ECM was chemically treated to cross-link its components, the cells were unable to ingest it. Further investigation indicated that uptake was through an ingestion process called macropinocytosis, in which the cell engulfs large quantities of extracellular material. What were the tumor cells after? Analysis of their metabolome indicated that procurement and breakdown of two amino acids, tyrosine and phenylalanine, dominated the metabolic changes in response to starvation. The authors noted that these two can serve as the raw material for energy production through the mitochondrial tricarboxylic acid (Krebs) cycle. When they knocked down HPDL, a central enzyme in the pathway from phenylalanine to the TCA, cell growth was significantly impaired. Blocking or reducing expression of HPDL, or the macropinocytosis promoter PAK1, reduced the ability of tumor cells to migrate and to invade surrounding tissue. These results indicate that breast cancer cells take advantage of nutrients in the extracellular matrix in times of nutrient starvation, and that this process depends on both macropinocytosis and metabolic conversion of key amino acids to energy-releasing substrates.

Nazemi M, Yanes B, Martinez ML, Walker HJ, Pham K, Collins MO, et al. (2024) The extracellular matrix supports breast cancer cell growth under amino acid starvation by promoting tyrosine catabolism. PLoS Biology (2024). DOI: 10.1371/journal.pbio.3002406

Comment by Dr. Krishna Kumari Challa on January 17, 2024 at 6:52am

Amnesia caused by head injury reversed in early mouse study

A mouse study designed to shed light on memory loss in people who experience repeated head impacts, such as athletes, suggests the condition could potentially be reversed. The research in mice finds that amnesia and poor memory following head injury are due to inadequate reactivation of neurons involved in forming memories.

The study, conducted by researchers is reported January 16, 2024, in The Journal of Neuroscience.

Importantly for diagnostic and treatment purposes, the researchers found that the memory loss attributed to head injury was not a permanent pathological event driven by a neurodegenerative disease. Indeed, the researchers could reverse the amnesia to allow the mice to recall the lost memory, potentially allowing cognitive impairment caused by head impact to be clinically reversed.
The  investigators had previously found that the brain adapts to repeated head impacts by changing the way the synapses in the brain operate. This can cause trouble in forming new memories and remembering existing memories. In their new study, investigators were able to trigger mice to remember memories that had been forgotten due to head impacts.

 Amnesia after repeated head impact is caused by impaired synaptic plasticity in the memory engram, The Journal of Neuroscience (2024).

Comment by Dr. Krishna Kumari Challa on January 17, 2024 at 6:42am

UK-wide study reveals harm done by people not getting COVID jabs

More than 7,000 people were hospitalized or died from COVID-19 in the UK during the summer of 2022 because they had not received the recommended number of vaccine doses, according to a study released Tuesday that was the first to cover Britain's entire population.

The researchers said the "landmark" population-wide study showed how important it is for people to keep getting booster jabs as COVID continues to pose a major health threat. More than 90 percent of the UK's adult population were vaccinated during the earlier stages of the pandemic. However, between June to September 2022, after the pandemic's emergency phase was declared over and attention turned elsewhere, around 44 percent of Britons were under-vaccinated, the researchers said. Using individual health data from the National Health Service (NHS) as well as modeling, the researchers estimated that there would have been 7,180 fewer hospitalizations or deaths if everyone had been up to date with their shots. That means that nearly 20 percent of the 40,000 COVID hospitalizations or deaths over the summer could have been avoided if Britons were fully vaccinated.

Undervaccination and severe COVID-19 outcomes: meta-analysis of national cohort studies in England, Northern Ireland, Scotland, and Wales, The Lancet (2024). DOI: 10.1016/S0140-6736(23)02467-4 , www.thelancet.com/journals/lan … (23)02467-4/fulltext

Comment by Dr. Krishna Kumari Challa on January 16, 2024 at 3:42pm

"We have finally unveiled the intricate story of when, where, and how plants respond to airborne 'warning messages' from their threatened neighbors," says Masatsugu Toyota, a molecular biologist at Saitama University in Japan and senior author of the study.

"This ethereal communication network, hidden from our view, plays a pivotal role in safeguarding neighboring plants from imminent threats in a timely manner."

The study has been published in Nature Communications.

https://www.sciencealert.com/scientists-film-plant-talking-to-its-n...

Part 4

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Comment by Dr. Krishna Kumari Challa on January 16, 2024 at 3:41pm

It wasn't a natural set-up; the compounds were concentrated in a plastic bottle and pumped onto the recipient plant at a constant rate, but this allowed the researchers to analyze what compounds were in the pungent mix.

As you can see in the video above, the undamaged plants received the messages of their injured neighbors loud and clear, responding with bursts of calcium signaling that rippled across their outstretched leaves.

Analyzing the airborne compounds, the researchers found that two compounds called Z-3-HAL and E-2-HAL induced calcium signals in Arabidopsis.

They also identified which cells are the first to respond to the danger cues by engineering Arabidopsis plants with fluorescent sensors exclusively in guard, mesophyll, or epidermal cells.

Guard cells are bean-shaped cells on plant surfaces that form stomata, small pores that open up to the atmosphere when plants 'breathe' in CO2. Mesophyll cells are the inner tissue of leaves, and epidermal cells are the outermost layer or skin of plant leaves.

When Arabidopsis plants were exposed to Z-3-HAL, guard cells generated calcium signals within a minute or so, after which mesophyll cells picked up the message.

What's more, pre-treating plants with a phytohormone that shuts stomata significantly reduced calcium signaling, suggesting stomata act as the 'nostrils' of the plant.
part 3

Comment by Dr. Krishna Kumari Challa on January 16, 2024 at 3:40pm

Caterpillars (Spodoptera litura) were set upon leaves cut from tomato plants and Arabidopsis thaliana, a common weed in the mustard family, and the researchers imaged the responses of a second, intact, insect-free Arabidopsis plant to those danger cues.

These plants weren't any ordinary weeds: they had been genetically altered so their cells contained a biosensor that fluoresced green when an influx of calcium ions was detected. Calcium signaling is something human cells use to communicate too.

The team used a similar technique to measure calcium signals in a study last year of fluorescent Mimosa pudica plants, which quickly move their leaves in response to touch, to avoid predators.

This time, the team visualized how plants responded to being bathed in volatile compounds, which plants release within seconds of wounding.

Part 2

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