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Category: chemistry

Senescence in cancer cells

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Sometimes, too much of a good thing can turn out to be bad. This is certainly the case for the excessive cell growth found in cancer. But when cancers try to grow too fast, this excessive speed can cause a type of cellular aging that actually results in arrested growth. Scientists at Duke-NUS Medical School have now discovered that a well-known signaling pathway helps cancers grow by blocking the pro-growth signals from a second major cancer pathway.

Inhibiting Wnt signaling with ETC-159 reactivates the hyperactive RAS-MAPK , causing cells to led undergo senescence. Many cancers are driven by activating mutations in the RAS-MAPK signaling pathway which triggers a cascade of proteins that directs cells to grow, divide and migrate. Mutations in proteins involved in this cascade can turn on genes that make this process go into overdrive, causing cells to grow out of control and aggressively invade other parts of the body. However, too much RAS-MAPK signaling causes cancer cells to prematurely age, and eventually stop growing—a process called cellular senescence.

Publishing in Cancer Research, the Duke-NUS research team found that another important and well-known biochemical pathway, the Wnt (pronounced “wint”) signaling pathway, allows some cancers to grow by dampening RAS-MAPK signaling.

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Circa 2018

The speed of space travel is currently limited by the quantity of chemical fuel that spacecraft must carry. Robert Zubrin, President of Pioneer Astronautics, introduces the dipole drive — a new propulsion system which uses ambient space plasma as propellant, thereby avoiding the need to carry its own.

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A new synthetic probe offers a safe and straightforward approach for visualizing chromosome tips in living cells. The probe was designed by scientists at the Institute for Integrated Cell-Material Science (iCeMS) and colleagues at Kyoto University, and could advance research into aging and a wide range of diseases, including cancers. The details were published in the Journal of the American Chemical Society.

“Chromosome ends are constantly at risk of degradation and fusion, so they are protected by structures called telomeres, which are made of long repeating DNA sequences and bound proteins,” says iCeMS chemical biologist Hiroshi Sugiyama, who led the study. “If telomeres malfunction, they are unable to maintain chromosome stability, which can lead to diseases such as cancer. Also, telomeres normally shorten with each cell division until they reach their limit, causing cell death.”

Visualizing telomeres, especially their physical arrangements in , is important for understanding their relevance to disease and aging. Several visualization approaches already exist, but they have disadvantages. For example, some can only observe telomeres in preserved, or fixed, cells. Others are time-consuming or involve harsh treatments that denature DNA.

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In Project Apollo, life support was based on carrying pretty much everything that astronauts needed from launch to splashdown. That meant all of the food, air, and fuel. Fuel in particular took up most of the mass that was launched. The enormous three-stage Saturn-V rocket was basically a gigantic container for fuel, and even the Apollo spacecraft that the Saturn carried into space was mostly fuel, because fuel was needed also to return from the Moon. If NASA’s new Orion spacecraft takes astronauts back to the Moon, they’ll also use massive amounts of fuel going back and forth; and the same is true if they journey to a near-Earth asteroid. However, once a lunar base is set up, astronauts will be able use microorganisms carried from Earth to process lunar rock into fuel, along with oxygen. The latter is needed not just for breathing, but also in rocket engines where it mixes with the fuel.

Currently, there are microorganisms available naturally that draw energy from rock and in the process release chemical products that can be used as fuel. However, as with agricultural plants like corn and soy, modifying such organisms can potentially make a biologically-based lunar rock processing much more efficient. Synthetic biology refers to engineering organisms to pump out specific products under specific conditions. For spaceflight applications, organisms can be engineered specifically to live on the Moon, or for that matter on an asteroid, or on Mars, and to synthesize the consumables that humans will need in those environments.

In the case of Mars, a major resource that can be processed by synthetic biology is the atmosphere. While the Martian air is extremely thin, it can be concentrated in a biological reactor. The principal component of the Martian air is carbon dioxide, which can be turned into oxygen, food, and rocket fuel by a variety of organisms that are native to Earth. As with the Moon rocks, however, genetic techniques can make targeted changes to organisms’ capabilities to allow them to do more than simply survive on Mars. They could be made to thrive there.

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Titan, the already pretty weird moon of Saturn, just got a little bit weirder. Astronomers have detected cyclopropenylidene (C3H2) in its atmosphere — an extremely rare carbon-based molecule that’s so reactive, it can only exist on Earth in laboratory conditions.

In fact, it’s so rare that it has never before been detected in an atmosphere, in the Solar System or elsewhere. The only other place it can remain stable is the cold void of interstellar space. But it may be a building block for more complex organic molecules that could one day lead to life.

“We think of Titan as a real-life laboratory where we can see similar chemistry to that of ancient Earth when life was taking hold here,” said astrobiologist Melissa Trainer of NASA’s Goddard Space Flight Center, one of the chief scientists set to investigate the moon in the upcoming Dragonfly mission launching in 2027.

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A researcher from The Australian National University (ANU) has used one of the most powerful supercomputers in the world to predict the quantum mechanical properties of large molecular systems with an accuracy that surpasses all previous experiments.

Calculations of this type have the potential to solve important problems in , fuel production, water purification, and the manufacturing of medicines, foods, textiles, and consumer goods.

By running his on the Summit supercomputer at the Oak Ridge National Lab in the U.S., Dr. Giuseppe Barca has broken the for the largest Hartree-Fock ever performed, setting new standards in High-Performance Computing.

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First introduced into wide use in the middle of the 20th century, nuclear magnetic resonance (NMR) has since become an indispensable technique for examining materials down to their atoms, revealing molecular structure and other details without interfering with the material itself.

“It’s a broadly used technique in , materials characterization, MRI—situations in which you do a non-invasive analysis, but with atomic and molecular details,” said UC Santa Barbara chemistry professor Songi Han. By placing a sample in a strong magnetic field and then probing it with radio waves scientists can determine from the response from the oscillating nuclei in the material’s atoms the of the material.

“However, the problem with NMR has been that because it’s such a low-energy technique, it’s not very sensitive,” Han said. “It’s very detailed, but you don’t get much signal.” As a result, large amounts of sample material may be needed relative to other techniques, and the signals’ general weakness makes NMR less than ideal for studying complex chemical processes.

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China faces an additional geopolitical challenge in chip fabrication and assembly. Just a handful of Japanese companies dominate the global market in silicon wafers, photoresists, and essential packaging chemicals. These companies are well-regarded for their high-quality production capabilities and their products are not easily replaceable even by a manufacturing heavyweight such as China. In a changing world where strategic concerns are guiding technology flows, China’s chip ambitions can be foiled not just by the US but also by Japan and Taiwan.

China’s state-backed funds may well spur private investment, even producing a few champions, but are unlikely to result in a self-sufficient Chinese chip industry any time soon.

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O,.o.

Physicists from MIPT and Vladimir State University, Russia, have converted light energy into surface waves on graphene with nearly 90% efficiency. They relied on a laser-like energy conversion scheme and collective resonances. The paper was published in Laser & Photonics Reviews.

Manipulating light at the nanoscale is a task crucial for being able to create ultracompact devices for optical conversion and storage. To localize light on such a small scale, researchers convert optical radiation into so-called plasmon-polaritons. These SPPs are oscillations propagating along the interface between two materials with drastically different refractive indices—specifically, a metal and a dielectric or air. Depending on the materials chosen, the degree of surface wave localization varies. It is the strongest for light localized on a material only one atomic layer thick, because such 2-D materials have high refractive indices.

The existing schemes for converting light to SPPs on 2-D surfaces have an efficiency of no more than 10%. It is possible to improve that figure by using intermediary signal converters—nano-objects of various chemical compositions and geometries.

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Magnets are to be found everywhere in our daily lives, whether in satellites, telephones or on fridge doors. However, they are made up of heavy inorganic materials whose component elements are, in some cases, of limited availability.

Now, researchers from the CNRS, the University of Bordeaux and the ESRF (European Synchrotron Radiation Facility in Grenoble)[1] have developed a new lightweight molecule-based magnet, produced at low temperatures, and exhibiting unprecedented magnetic properties.

This compound, derived from coordination chemistry[2], contains chromium, an abundant metal, and inexpensive organic molecules. This is the first molecule-based magnet that exhibits a ‘memory effect’ (i.e. it is capable of maintaining one of its two magnetic states) up to a temperature of 240 °C. This effect is measured by what is known as a coercive field, which is 25 times higher at room temperature for this novel material than for the most efficient of its molecule-based predecessors. This property therefore compares well with that of certain purely inorganic commercial magnets.

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