Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: chemistry – Page 97

An MIT study suggests 3D folding of the genome is key to cells’ ability to store and pass on “memories” of which genes they should express.

Every cell in the human body contains the same genetic instructions, encoded in its DNA. However, out of about 30,000 genes, each cell expresses only those genes that it needs to become a nerve cell, immune cell, or any of the other hundreds of cell types in the body.

Each cell’s fate is largely determined by chemical modifications to the proteins that decorate its DNA; these modification in turn control which genes get turned on or off. When cells copy their DNA to divide, however, they lose half of these modifications, leaving the question: How do cells maintain the memory of what kind of cell they are supposed to be?

A new MIT study proposes a theoretical model that helps explain how these memories are passed from generation to generation when cells divide. The research team suggests that within each cell’s nucleus, the 3D folding of its genome determines which parts of the genome will be marked by these chemical modifications. After a cell copies its DNA, the marks are partially lost, but the 3D folding allows the cell to easily restore the chemical marks needed to maintain its identity. And each time a cell divides, chemical marks allow a cell to restore its 3D folding of its genome. This way, by juggling the memory between 3D folding and the marks, the memory can be preserved over hundreds of cell divisions.

Continue reading “How cell identity is preserved when cells divide” | >

To achieve high intrinsic gain (Ai) in OTFTs, it is necessary to enlarge output resistance (ro) or transconductance (gm) according to a typical formula of Ai = gmro, which is very difficult for conventional OTFTs because of inherent device structure and operating mode limitations (11, 12). Recently, the “Schottky barrier” (SB) strategy based on metal-semiconductor junction (MS junction) has been adopted in TFTs to pursue high-gain and low-saturation voltage, including subthreshold SB-TFTs (11, 12, 15, 16) and source-gated transistors (17, 18). Unfortunately, the subthreshold transistors are limited in low and narrow subthreshold operating region rather than the normal ON-state region (namely, the normal voltage operating region in a typical TFT), which are difficult to be compatible with typical circuits. As far as we know, the ultrahigh-gain (1000) OTFTs operating in the ON-state region have not been previously reported. On the other hand, the state-of-the-art OTFTs above have mostly suffered from uncontrollable barriers owing to energy-level mismatches and a series of complex interface problems, such as Fermi-level pinning and interface chemical disorder (19). In this case, considerable low-energy carriers are allowed to pass through the junction by thermionic field emission and tunneling models instead of thermionic emission model, which is not conducive to obtaining a high output resistance and high intrinsic gain. Most barrier heights in MS junction do not conform to the prediction value of Schottky-Mott rule. Theoretically, an ideal and high-quality barrier with thermionic emission model allows the rapid depletion of carriers at the source electrode, thus yielding ultrahigh gain, infinite output resistance, and low saturation voltage (11, 12). In addition, infinite output resistance at the saturation regime indicates that the output current is very stable and flat. This performance is helpful because only a single OTFT is used as a simplified current stabilizer in circuits without complex circuit design, which benefits low power and low cost in circuits. Therefore, it is necessary to develop a high-quality barrier strategy to modulate charge injection to meet the requirements of ultrahigh-gain OTFTs.

Here, we demonstrate a metal-barrier interlayer-semiconductor (MBIS) junction to prepare high-performance MBIS-OTFT with an ultrahigh gain of ~104 in the ON-state region, low saturation voltage, almost negligible hysteresis, and good stability. On the basis of low-energy processes and in situ surface oxidation technology, the high-quality van der Waals MBIS junction with wide-bandgap semiconductor (mainly Ga2O3) interlayer is achieved, allowing for an adjustable barrier height and thermionic emission properties. A series of in situ experiments and simulations revealed the relationship between the barriers and the device’s performance. Furthermore, as demonstrations, a simplified current stabilizer and an ultrahigh-gain organic inverter are exhibited without complex circuit design.

Read more | >

Per-and polyfluoroalkyl substances (PFAS), manufactured chemicals used in products such as food packaging and cosmetics, can lead to reproductive problems, increased cancer risk and other health issues. A growing body of research has also linked the chemicals to lower bone mineral density, which can lead to osteoporosis and other bone diseases. But most of those studies have focused on older, non-Hispanic white participants and only collected data at a single point in time.

Now, researchers from the Keck School of Medicine of USC have replicated those results in a of two groups of young participants, primarily Hispanics, a group that faces a heightened risk of disease in adulthood.

“This is a population completely understudied in this area of research, despite having an increased risk for bone disease and osteoporosis,” said Vaia Lida Chatzi, MD, Ph.D., a professor of population and public health sciences at the Keck School of Medicine and the study’s senior author.

Read more | >

One of nature’s most common organic materials—lignin—can be used to create stable and environmentally friendly organic solar cells. Researchers at Linköping University and the Royal Institute of Technology (KTH) have now shown that untreated kraft lignin can be used to make solar cells even more environmentally friendly and reliable. The study has been published in the journal Advanced Materials.

Sunlight currently seems to be one of the main sustainable energy sources. Traditional made from silicon are efficient but have an energy-demanding and complicated manufacturing process that may lead to hazardous chemical spills. Organic solar cells have therefore become a hot research area thanks to their low production cost, light weight and flexibility, and hence have many applications, such as indoor use or attached to clothing to power personal electronic devices.

But one problem is that are made of plastic, or polymers derived from oil. So, although organic, they are not as environmentally friendly as they could be.

Read more | >

Could a fecal transplant pill be the antidepressants of the future?

Depression is real, and it is complex. Most conditions that affect our brain chemistry are going to be complex, and there are no easy, simple answers. We can’t cure depression by just exercising more, eating better, or taking a short vacation to recharge (although there is some evidence that getting more money, especially to lift you out of poverty, helps relieve depressive symptoms).

Read more | >

Micrometeorites, tiny space rocks, may have helped deliver nitrogen, a vital life ingredient, to Earth during our solar system’s early days. This finding was published in Nature Astronomy on November 30 by an international research team, including scientists from the University of Hawaiʻi at Mānoa and Kyoto University. They discovered that nitrogen compounds like ammonium salts are common in material from regions distant from the sun. However, how these compounds reached Earth’s orbit was unclear.

The study suggests that more nitrogen compounds were transported near Earth than previously thought. These compounds could have contributed to life on our planet. The research was based on material collected from the asteroid Ryugu by Japan’s Hayabusa2 spacecraft in 2020. Ryugu, a small sun-orbiting rocky object, is carbon-rich and has experienced considerable space weathering due to micrometeorite impacts and solar charged ions.

The scientists studied the Ryugu samples to understand the materials reaching Earth’s orbit. They used an electron microscope and found the Ryugu samples’ surface covered with tiny iron and nitrogen minerals. They theorized that micrometeorites carrying ammonia compounds collided with Ryugu. This collision sparked chemical reactions on magnetite, resulting in iron nitride formation.

Read more | >

When Emiliano Cortés goes hunting for sunlight, he doesn’t use gigantic mirrors or sprawling solar farms. Quite the contrary, the professor of experimental physics and energy conversion at LMU dives into the nanocosmos.

“Where the high-energy particles of , the photons, meet atomic structures is where our research begins,” Cortés says. “We are working on material solutions to capture and use solar energy more efficiently.”

His findings have great potential as they enable novel solar cells and photocatalysts. The industry has high hopes for the latter because they can make accessible for chemical reactions—bypassing the need to generate electricity. But there is one major challenge to using sunlight, which solar cells also have to contend with, Cortés knows: “Sunlight arrives on Earth ‘diluted,’ so the energy per area is comparatively low.” Solar panels compensate for this by covering large areas.

Read more | >

Summary: Dopamine, a neurotransmitter, plays a vital role in encoding both reward and punishment prediction errors in the human brain.

This study suggests that dopamine is essential for learning from both positive and negative experiences, enabling the brain to adapt behavior based on outcomes. Using electrochemical techniques and machine learning, scientists measured dopamine levels in real-time during a computer game involving rewards and penalties.

The findings shed light on the intricate role of dopamine in human behavior and could have implications for understanding psychiatric and neurological disorders.

Read more | >

Pentoses are essential carbohydrates in the metabolism of modern lifeforms, but their availability during early Earth is unclear since these molecules are unstable.

A new study, published in the journal JACS Au and led by the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology, Japan, reveals a chemical pathway compatible with early Earth conditions and by which C6 aldonates could have acted as a source of pentoses without the need for enzymes. Their findings provide clues about primitive biochemistry and bring us closer to understanding the Origins of Life.

The emergence of life on Earth from simple chemicals is one of the most exciting yet challenging topics in biochemistry and perhaps all of science. Modern lifeforms can transform nutrients into all sorts of compounds through complex chemical networks; what’s more, they can catalyze very specific transformations using enzymes, achieving a very fine control over what molecules are produced.

Read more | >