Comment

Comment by Dr. Krishna Kumari Challa on February 2, 2022 at 10:36am

To do this, the researchers had to couple tried and tested scanning tunnelling microscopy with state-of-the-art laser technology. In a scanning tunnelling microscope, a wafer-thin, atomically thin tip travels just above a conductive surface. Thanks to the quantum-physical tunnel effect, electrons can flow between the surface and the microscope tip – even if there is no direct contact. For example, a molecule on a surface can gradually be shaved off atom by atom.

The new microscopy technique uses laser pulses in order to modulate the tunnel current by selectively exciting the electrons in the material. “This must be done extremely quickly. Otherwise, thermal effects come into play and make the measurements impossible. 

Thanks to the rapid development of laser technology in recent years, researchers have now been able to generate precisely the right pulses. Two years ago, Garg and Kern demonstrated the function of such an atomic quantum microscope for the first time.

They have now been able to directly observe electron movement in molecules with this one-of-a-kind instrument. With the help of the ultra-short pulses, the electrons in the molecule can be excited to jump between the different orbitals. This was noticeable in the tunnel flow. The highlight of the new technique is being able to fire two minimally time-delayed pulses in quick succession at the molecule to be investigated with an exact time interval and scan it in the process. If this procedure is repeated several times and the time interval between the pulses varied, an image series that reproduces the behaviour of the electrons in this molecule with atomic accuracy is obtained. The fast laser pulses thus provide the information about the electron dynamics whilst the scanning tunnelling microscope precisely scans the molecule.

This allowed the researchers to directly map the dynamics of electrons in molecules – how they jump from one orbital to another – for the first time. This basic technology provides completely new possibilities for directly observing quantum mechanical processes such as charge transfer in individual molecules and thus better understanding them. It is still not possible to predict the possible areas of application for such a quantum microscope. Especially in charge transfer processes, which play a crucial role in many biophysical reactions as well as in solar cells and transistors, it could provide crucial new insights.

https://www.mpg.de/18173993/quantum-leap-electron-film

Comment by Dr. Krishna Kumari Challa on February 2, 2022 at 10:33am

Quantum leap on film

 In order to better understand (and possibly control) fast chemical reactions, it is necessary to study the behaviour of electrons as precisely as possible – in both space and time. However, up to now, microscopy methods have delivered only either spatially or temporally sharp images. By cleverly combining established techniques of tunnelling microscopy and laser spectroscopy, a team of researchers has now overcome these obstacles. Using their atomic quantum microscope, they can make the movement of electrons in individual molecules visible.

It is essential not only for understanding biological processes (e.g. plant photosynthesis) to map the electron dynamics in molecules but also for many technical applications such as the development of solar cells or new types of electronic components. Until now, imaging methods have sometimes delivered images that are difficult to reproduce – or even contradictory. This is because they cannot map the fast electrons directly but rather must resort to techniques that can only reconstruct the behaviour of the electrons.

Although modern microscopy techniques offer almost unlimited possibilities, certain compromises must be made. For example, scanning tunnelling microscopy with a resolution of one tenth of a picometre (1 × 10−12 m) allows extremely sharp images of individual atoms to be taken. However, this is slow and cannot capture the electron dynamics in a material. On the other hand, optical methods with ultra-fast laser pulses can detect electron movements in the attosecond (1 × 10−18 of a second) range. However, they can provide only coarse, washed-out spatial images – far removed from the atomic resolution possible with scanning tunnelling microscopes. The typical electron dynamics and laser pulses are in the range of a few hundred attoseconds.

Part 1

Comment by Dr. Krishna Kumari Challa on February 2, 2022 at 10:30am

Key growth factor protects gut from inflammatory bowel disease

IBD, a disease category including ulcerative colitis and Crohn's disease, features chronic gut inflammation and many potential follow-on effects including arthritis and colorectal cancer.

 A growth factor protein produced by rare immune cells in the intestine can protect against the effects of inflammatory bowel disease (IBD), according to a new discovery. 

In their study, published in Nature Immunology, the researchers found that the growth factor, HB-EGF, is produced in response to gut inflammation by a set of immune-regulating cells called ILC3s. These immune cells reside in many organs including the intestines, though their numbers are known to be depleted in the inflamed intestines of IBD patients.

The researchers showed in experiments in mice that this growth factor can powerfully counter the harmful effects of a key driver of intestinal inflammation called TNF. In doing so, ILC3s protect gut-lining cells when they would otherwise die and cause a breach in the intestinal barrier. 

Lei Zhou, Wenqing Zhou, Ann M. Joseph, Coco Chu, Gregory G. Putzel, Beibei Fang, Fei Teng, Mengze Lyu, Hiroshi Yano, Katrin I. Andreasson, Eisuke Mekada, Gerard Eberl, Gregory F. Sonnenberg. Group 3 innate lymphoid cells produce the growth factor HB-EGF to protect the intestine from TNF-mediated inflammation. Nature Immunology, 2022; DOI: 10.1038/s41590-021-01110-0

https://researchnews.cc/news/11380/Key-growth-factor-protects-gut-f...

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 1:07pm

Missing ear bone helps bats to echolocate

Some bats have an anatomical quirk in their ears that could explain how they evolved to hunt in specialized ways, from sensing small fish to catching insects midflight. In 2015, researchers took 3D images of the inner ear of a bat skull but couldn’t find a feature shared by almost all mammals: a bony tube that connects the ear to the brain and encases nerve cells. A more thorough search revealed many more bat species in which this bony nerve channel was missing or poked with large holes. Researchers suspect the loss of this bony channel gave the bats new hearing capabilities because the nerves are less confined.

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 12:41pm

How  Climate Change is Affecting Hibernation?

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 12:36pm

To test the particles, the researchers first injected them into the stomachs of mice, without using the delivery capsule. The RNA that they delivered codes for a reporter protein that can be detected in tissue if cells successfully take up the RNA. The researchers found the reporter protein in the stomachs of the mice and also in the liver, suggesting that RNA had been taken up in other organs of the body and then carried to the liver, which filters the blood.

Next, the researchers freeze-dried the RNA-nanoparticle complexes and packaged them into their drug delivery capsules. Working with scientists at Novo Nordisk, they were able to load about 50 micrograms of mRNA per capsule, and delivered three capsules into the stomachs of pigs, for a total of 150 micrograms of mRNA. This is the more than the amount of mRNA in the COVID vaccines now in use, which have 30 to 100 micrograms of mRNA.

In the pig studies, the researchers found that the reporter protein was successfully produced by cells of the stomach, but they did not see it elsewhere in the body. In future work, they hope to increase RNA uptake in other organs by changing the composition of the nanoparticles or giving larger doses. However, it may also be possible to generate a strong immune response with delivery only to the stomach.

"There are many immune cells in the gastrointestinal tract, and stimulating the immune system of the gastrointestinal tract is a known way of creating an immune response.

 Giovanni Traverso, Oral mRNA delivery using capsule-mediated gastrointestinal tissue injections, Matter (2022). DOI: 10.1016/j.matt.2021.12.022. www.cell.com/matter/fulltext/S2590-2385(21)00680-9

https://medicalxpress.com/news/2022-01-pill-rna-stomach-vaccines.ht...

Part 3

**

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 12:35pm

For several years, scientists have been developing novel ways to deliver drugs to the gastrointestinal tract. In 2019, the researchers designed a capsule that, after being swallowed, can place solid drugs, such as insulin, into the lining of the stomach.

The pill, about the size of a blueberry, has a high, steep dome inspired by the leopard tortoise. Just as the tortoise is able to right itself if it rolls onto its back, the capsule is able to orient itself so that its contents can be injected into the lining of the stomach.

In 2021, the researchers showed that they could use the capsule to deliver large molecules such as monoclonal antibodies in liquid form. Next, the researchers decided to try to use the capsule to deliver nucleic acids, which are also large molecules.

Nucleic acids are susceptible to degradation when they enter the body, so they need to be carried by protective particles. For this study, the  team used a new type of polymeric nanoparticle  they had recently developed.

These particles, which can deliver RNA with high efficiency, are made from a type of polymer called poly(beta-amino esters). The MIT team's previous work showed that branched versions of these polymers are more effective than linear polymers at protecting nucleic acids and getting them into cells. They also showed that using two of these polymers together is more effective than just one.

Part 2

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 12:33pm

A pill that releases RNA in the stomach could offer a new way to administer vaccines

Like most vaccines, RNA vaccines have to be injected, which can be an obstacle for people who fear needles. Now, a team of  researchers has developed a way to deliver RNA in a capsule that can be swallowed, which they hope could help make people more receptive to them.

In addition to making vaccines easier to tolerate, this approach could also be used to deliver other kinds of therapeutic RNA or DNA directly to the digestive tract, which could make it easier to treat gastrointestinal disorders such as ulcers.

Nucleic acids, in particular RNA, can be extremely sensitive to degradation particularly in the digestive tract. Overcoming this challenge opens up multiple approaches to therapy, including potential vaccination through the oral route.

In a new study, researchers showed that they could use the capsule they developed to deliver up to 150 micrograms of RNA—more than the amount used in mRNA COVID vaccines—in the stomach of pigs.

part 1

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 11:55am

Melting causes gradients in the temperature of the water near the ice, which causes the liquid at different places to have different densities. This generates flows due to gravity—with heavier liquid sinking and lighter fluid rising—and such flows along the surface lead to different rates of melting at different locations and thus changes in shape.

The strange bit of physics is that liquid water has a highly unusual dependence of density on temperature, in particular a maximum of density at about 4 degrees C. "This 'density anomaly' makes water unique in comparison to other fluids."

The research shows that this property is responsible for producing very different flows, depending on the precise value of the water temperature. The downward pinnacles at low temperatures are associated with upward flows, while the upward pinnacles have downward flows. The scalloped patterns form because upward flows very near the surface interact with downward flows further away, destabilizing into vortices that carve pits into the ice.

Scott Weady et al, Anomalous Convective Flows Carve Pinnacles and Scallops in Melting Ice, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.128.044502

https://phys.org/news/2022-01-scientists-uncover-ice-temperature.ht...

Part 2

Comment by Dr. Krishna Kumari Challa on February 1, 2022 at 11:53am

Scientists uncover how the shape of melting ice depends on water temperature

A team of mathematicians and physicists has discovered how ice formations are shaped by external forces, such as water temperature. Its newly published research may offer another means for gauging factors that cause ice to melt.

The shapes and patterning of ice are sensitive indicators of the environmental conditions at which it melted, allowing researchers to 'read' the shape to infer factors such as the ambient water temperature. This  helps to understand how melting induces unusual flow patterns that in turn affect melting, which is one of the many complexities affecting the ice on our planet.

The researchers studied, through a series of experiments, the melting of ice in water and, in particular, how the water temperature affects the eventual shapes and patterning of ice. To do so, they created ultra-pure ice, which is free of bubbles and other impurities. The team recorded the melting of ice submerged into water tanks in a "cold room," which is similar to a walk-in refrigerator whose temperature is controlled and varied.

They focused on the cold temperatures—0 to 10 degrees Celsius—at which ice in natural waters typically melts, and  found a surprising variety of shapes that formed. 

Specifically, at very cold temperatures—those under about 5 degrees C—the pieces take on the shape of a spike or "pinnacle" pointing downward—similar to an icicle, but perfectly smooth (with no ripples). For temperatures above approximately 7 degrees C, the same basic shape forms, but upside down—a spike pointing upward. For in between temperatures, the ice has wavy and rippled patterns melted into its surface. Similar patterns, called "scallops," are found on icebergs and other ice surfaces in nature.

These shape differences are due to changes in water flows, which are determined by their temperatures.

Part 1

• ‹ Previous
• 1
• …
• 293
• 294
• 295
• 296
• 297
• …
• 849
• Next ›
• Page