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Comment by Dr. Krishna Kumari Challa on October 17, 2020 at 7:40am

Zeptoseconds: New world record in short time measurement

In 1999,  chemist Ahmed Zewail received the Nobel Prize for measuring the speed at which molecules change their shape. He founded femtochemistry using ultrashort laser flashes: the formation and breakup of chemical bonds occurs in the realm of femtoseconds.

Now, atomic physicists have for the first time studied a process that is shorter than femtoseconds by magnitudes. They measured how long it takes for a photon to cross a hydrogen molecule: about 247 zeptoseconds for the average bond length of the molecule. This is the shortest timespan that has been successfully measured to date.

The scientists carried out the time measurement on a hydrogen molecule (H₂) which they irradiated with X-rays from the X-ray laser source PETRA III at the Hamburg accelerator facility DESY. The researchers set the energy of the X-rays so that one photon was sufficient to eject both electrons out of the hydrogen molecule.

Zeptosecond Birth Time Delay in Molecular Photoionization, Science (2020). DOI: 10.1126/science.abb9318

https://phys.org/news/2020-10-zeptoseconds-world-short.html?utm_sou...

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Electrons behave like particles and waves simultaneously, and therefore the ejection of the first electron resulted in electron waves launched first in the one, and then in the second hydrogen molecule atom in quick succession, with the waves merging.

The photon behaved here much like a flat pebble that is skimmed twice across the water: when a wave trough meets a wave crest, the waves of the first and second water contact cancel each other, resulting in what is called an interference pattern.

The scientists measured the interference pattern of the first ejected electron using the COLTRIMS reaction microscope, an apparatus that Dörner helped develop and which makes ultrafast reaction processes in atoms and molecules visible. Simultaneously with the interference pattern, the COLTRIMS reactions microscope also allowed the determination of the orientation of the hydrogen molecule. The researchers here took advantage of the fact that the second electron also left the hydrogen molecule, so that the remaining hydrogen nuclei flew apart and were detected.

Comment by Dr. Krishna Kumari Challa on October 17, 2020 at 7:27am

Ultrafast camera films 3-D movies at 100 billion frames per second

In his quest to bring ever-faster cameras to the world researchers  have developed technology that can reach blistering speeds of 70 trillion frames per second, fast enough to see light travel. Just like the camera in your cell phone, though, it can only produce flat images.

Now, they have gone a step further to create a camera that not only records video at incredibly fast speeds but does so in three dimensions.

The new camera, which uses the same underlying technology as other compressed ultrafast photography (CUP) cameras, is capable of taking up to 100 billion frames per second. That is fast enough to take 10 billion pictures, more images than the entire human population of the world, in the time it takes you to blink your eye.

Single-shot stereo-polarimetric compressed ultrafast photography for light-speed observation of high-dimensional optical transients with picosecond resolution, Nature Communications (2020).

https://www.nature.com/articles/s41467-020-19065-5

https://phys.org/news/2020-10-ultrafast-camera-d-movies-billion.htm...

Comment by Dr. Krishna Kumari Challa on October 17, 2020 at 6:38am

Calcium bursts kill drug-resistant tumour cells

Multidrug resistance (MDR)—a process in which tumors become resistant to multiple medicines—is the main cause of failure of cancer chemotherapy. Tumor cells often acquire MDR by boosting their production of proteins that pump drugs out of the cell, rendering the chemotherapies ineffective. Now, researchers reporting in ACS' Nano Letters have developed nanoparticles that release bursts of calcium inside tumor cells, inhibiting drug pumps and reversing MDR.

A pump protein called P-glycoprotein (P-gp) often plays a key role in MDR. P-gp is in the cell membrane, where it uses energy in the form of adenosine triphosphate (ATP) to pump drugs out of tumor cells. Scientists have tried to block P-gp in various ways, such as with small-molecule inhibitors or by depleting ATP. However, the strategies used so far can cause side effects, or they are unstable in the body. Some of the treatments can be difficult to prepare. Kaixiang Zhang, Zhenzhong Zhang, Jinjin Shi and colleagues wanted to block P-gp using a different approach. Previous research suggested that overloading tumor cells with calcium ions could both decrease production of P-gp and reduce ATP levels. But the team needed to find a way to deliver bursts of calcium, along with a chemotherapy drug, inside cancer cells.

The researchers made a "calcium ion nanogenerator" (TCaNG) by loading calcium phosphate nanoparticles with the chemotherapy drug doxorubicin and then coating them with molecules that would allow TCaNG to target and enter cancer cells. Once inside cells, TCaNGs entered an acidic compartment, where the TCaNGs disintegrated, releasing both doxorubicin and bursts of calcium ions. When the team tested TCaNG on cancer cells in a petri dish in the lab, both ATP and P-gp production decreased, which allowed doxorubicin to kill the previously resistant tumor cells. When tested in tumor-bearing mice, TCaNG-treated mice showed significantly smaller tumors after 21 days of treatment than control mice, with no apparent side effects.

Junjie Liu et al, Nanoenabled Intracellular Calcium Bursting for Safe and Efficient Reversal of Drug Resistance in Tumor Cells, Nano Letters (2020). DOI: 10.1021/acs.nanolett.0c03042

https://phys.org/news/2020-10-calcium-drug-resistant-tumor-cells.ht...

Comment by Dr. Krishna Kumari Challa on October 17, 2020 at 6:28am

**Groundbreaking discovery finally proves rain really can move mountains

A pioneering technique that captures precisely how mountains bend to the will of raindrops has helped to solve a long-standing scientific enigma.

The dramatic effect rainfall has on the evolution of mountainous landscapes is widely debated among geologists, but new research led by the University of Bristol and published today in Science Advances, clearly calculates its impact, furthering our understanding of how peaks and valleys have developed over millions of years. Its findings, which focused on the mightiest of mountain ranges—the Himalaya—also pave the way for forecasting the possible impact of climate change on landscapes and, in turn, human life.

It may seem intuitive that more rain can shape mountains by making rivers cut down into rocks faster. But scientists have also thought rain can erode a landscape quickly enough to essentially 'suck' the rocks out of the Earth, effectively pulling mountains up very quickly. Both these theories have been debated for decades because the measurements required to prove them are so painstakingly complicated. That's what makes this discovery such an exciting breakthrough, as it strongly supports the notion that atmospheric and solid earth processes are intimately connected.

When a cosmic particle from outer space reaches Earth, it is likely to hit sand grains on hillslopes as they are transported toward rivers. When this happens, some atoms within each grain of sand can transform into a rare element. By counting how many atoms of this element are present in a bag of sand, we can calculate how long the sand has been there, and therefore how quickly the landscape has been eroding. Once we have erosion rates from all over the mountain range, we can compare them with variations in river steepness and rainfall. However, such a comparison is hugely problematic because each data point is very difficult to produce and the statistical interpretation of all the data together is complicated.

The new model  allows us for the first time to quantify how rainfall affects erosion rates in rugged terrain. Their findings  show how critical it is to account for rainfall when assessing patterns of tectonic activity using topography, and also provide an essential step forward in addressing how much the slip rate on tectonic faults may be controlled by climate-driven erosion at the surface. The study findings also carry important implications for land use management, infrastructure maintenance, and hazards in the Himalaya.

Climate controls on erosion in tectonically active landscapes, Science Advances (2020). advances.sciencemag.org/lookup … .1126/sciadv.aaz3166

https://phys.org/news/2020-10-groundbreaking-discovery-mountains.ht...

Comment by Dr. Krishna Kumari Challa on October 16, 2020 at 10:15am

Glowing blue helps shield this tardigrade from harmful ultraviolet light

Fluorescence may allow water bears to survive in especially sunny regions

When blasted with ultraviolet radiation, a newly discovered species of tardigrade protects itself by glowing blue.

Tardigrades, microscopic animals also known as water bears or moss piglets, are nature’s ultimate survivor. They’re game for temperatures below –270° Celsius and up to 150° C and can withstand the vacuum of space, and some are especially resistant to harmful UV radiation .   One tardigrade ( belonging to the genus Paramacrobiotus)shields itself from that UV radiation with glowing pigments, a new study suggests. It’s the first experimental evidence of fluorescent molecules protecting animals from radiation

H.R. Suma, S. Prakash and S.M. Eswarappa. Naturally occurring fluorescence protects the eutardigrade Paramacrobiotus sp. from ultraviolet radiation. Biology Letters. Published online October 14, 2020. doi: 10.1098/rsbl.2020.0391.

https://www.sciencenews.org/article/tardigrade-water-bear-glow-blue...

Comment by Dr. Krishna Kumari Challa on October 16, 2020 at 9:30am

** Need to be in two places at once? It may be possible

https://researchnews.cc/news/3052/Need-to-be-in-two-places-at-once-...

Comment by Dr. Krishna Kumari Challa on October 16, 2020 at 9:23am

How the brain quenches the thirst in different ways ....

After eating a bag of salty potato chips, you probably feel thirsty. And after a long period of exercise, you also probably feel thirsty. However, these two types of thirst are not the same.

In the first example, you would likely reach for water. This is because after eating chips, the concentration of salts and minerals in your blood becomes elevated, which induces a state called osmotic thirst. On the other hand, after exercising, you are likely to reach for Gatorade or some other fluid that can both rehydrate you and replenish electrolytes, minerals that are important for the body functions. This thirst, called hypovolemic thirst, occurs when the volume of your blood is reduced due to fluid loss from sweating.

Now researchers have discovered unique populations of neurons in the mouse brain that separately drive osmotic thirst and hypovolemic thirst. The research exploited a high-throughput and robust technique for mapping neurons that are activated by a specific behaviour or stimulus.

Two brain regions are known to be important in drinking behaviors in mammals, the subfornical organ (SFO) and the organum vasculosum laminae terminalis (OVLT). The Oka laboratory previously demonstrated that each of these regions contains two general categories of neurons: some that induce drinking behavior and others that inhibit it.

The mice were then genetically modified so that the team could activate the osmolality- and hypovolemia-sensitive neurons with pulses of light, through a technique called optogenetics. The researchers showed that the activation of the osmolality-sensitive neurons drove the mice to drink pure water and to avoid salty water. In contrast, when hypovolemia-sensitive neurons were activated, the mice showed an appetite for mineral-rich liquids.
The results show that thirst is a multimodal sensation caused by distinct stimuli. This is an exciting finding because it illustrates how our brain senses internal states using a very similar strategy as peripheral sensory systems such as taste and olfaction

https://www.caltech.edu/about/news/brain-quenches-thirst-different-...

https://researchnews.cc/news/3054/The-brain-quenches-thirst-in-diff...

Comment by Dr. Krishna Kumari Challa on October 16, 2020 at 9:17am

Reviving cells after a heart attack

Researchers unravel the healing mechanisms of extracellular vesicles and demonstrate their healing power on a heart-on-a-chip

Comment by Dr. Krishna Kumari Challa on October 16, 2020 at 9:11am

A hydrogel that could help repair damaged nerves
Injuries to peripheral nerves –– tissues that transmit bioelectrical signals from the brain to the rest of the body –– often result in chronic pain, neurologic disorders, paralysis or disability. Now, researchers have developed a stretchable conductive hydrogel that could someday be used to repair these types of nerves when there’s damage.

Injuries in which a peripheral nerve has been completely severed, such as a deep cut from an accident, are difficult to treat. A common strategy, called autologous nerve transplantation, involves removing a section of peripheral nerve from elsewhere in the body and sewing it onto the ends of the severed one. However, the surgery does not always restore function, and multiple follow-up surgeries are sometimes needed. Artificial nerve grafts, in combination with supporting cells, have also been used, but it often takes a long time for nerves to fully recover.

Now researchers prepared a tough but stretchable conductive hydrogel containing polyaniline and polyacrylamide. The crosslinked polymer had a 3D microporous network that, once implanted, allowed nerve cells to enter and adhere, helping restore lost tissue. They showed that the material could conduct bioelectrical signals through a damaged sciatic nerve removed from a toad. Then, they implanted the hydrogel into rats with sciatic nerve injuries. Two weeks later, the rats’ nerves recovered their bioelectrical properties, and their walking improved compared with untreated rats. Because the electricity-conducting properties of the material improve with irradiation by near-infrared light, which can penetrate tissues, it could be possible to further enhance nerve conduction and recovery in this way, the researchers say.

https://www.acs.org/content/acs/en/pressroom/newsreleases/2020/octo...

https://researchnews.cc/news/3043/A-hydrogel-that-could-help-repair...

Comment by Dr. Krishna Kumari Challa on October 16, 2020 at 8:51am

The Lancet: Herd immunity approaches to COVID-19 control are a 'dangerous fallacy', say authors of open letter

A group of 80 researchers warn that a so-called herd immunity approach to managing COVID-19 by allowing immunity to develop in low-risk populations while protecting the most vulnerable is "a dangerous fallacy unsupported by the scientific evidence".

The open letter, referred to by its authors as the John Snow Memorandum, is published today by The Lancet. It is signed by 80 international researchers (as of publication) with expertise spanning public health, epidemiology, medicine, paediatrics, sociology, virology, infectious disease, health systems, psychology, psychiatry, health policy, and mathematical modelling [1]. The letter will also be launched during the 16th World Congress on Public Health programme 2020.

https://www.eurekalert.org/pub_releases/2020-10/tl-pss101420.php

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