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Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 9:55am

The researchers used charged polymethylmethacrylate particles with different diameters (large and small) to carry out the experiment. A low-polar solvent, cyclohexyl bromide, was used as a dispersing agent.

As the researchers point out, although in both granular (e.g., nut) and colloidal mixtures the "Brazil nut effect" occurs, the mechanisms for its formation are completely different. In the case of a nut mixture, as a result of shaking, smaller nuts fill in the gaps created at the bottom, pushing the larger nuts to the top.

Meanwhile, the charged particles in the colloid make Brownian motion as a result of collisions with the surrounding solvent molecules. "Each particle is positively charged. Heavier but larger particles have a greater charge, so they repel each other more strongly, making them move upward more easily than smaller but lighter particles

The discovery of the "Brazil nut effect" in mixtures of colloidal particles can be used in many fields from geology to soft matter physics. It can also find application in industry such as in the stability of paint and ink.

 Marjolein N. van der Linden et al, Realization of the Brazil-nut effect in charged colloids without external driving, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2213044120

Part 2

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 9:54am

Defying gravity with the Brazil nut effect

Physicists  have observed—for the first time experimentally—the Brazil nut effect in a mixture of charged colloidal particles.

Until now, it was thought that an influx of external energy was required to create this effect—but the researchers were able to confirm that the process can occur spontaneously. 

Shake an open bag of mixed nuts. Have you noticed that after such a procedure, the largest nuts in the mixture—Brazil nuts—float to the top? The phenomenon of large objects rising to the surface of a mixture of small objects, bearing the professional name of granular convection, is popularly referred to "the Brazil nut effect" and occurs commonly in nature. It can also be observed by shaking, for example, a bucket of sand and pebbles.

This unusual effect contradicts the intuition that heavier objects should sink to the bottom due to gravity and inertia force. This is the case with the phenomenon of sedimentation, common in nature, a process involving the sinking of solid particles dispersed in a liquid, under the influence of gravity or inertia forces. Sedimentation plays a role in processes such as the formation of sedimentary rocks, and is also used to purify water and wastewater or isolate cells from blood.

Until now, it was thought that an influx of external energy, such as shaking the bag, was necessary to create the Brazil nut effect. However, theoretical models being developed suggested that the phenomenon could occur spontaneously, without the supply of external energy. The theoretical calculations were confirmed experimentally for the first time by a group of experimental and theoretical physicists.

They  have shown that the Brazil nut effect can take place in a mixture of charged colloidal particles driven solely by Brownian motions and repulsion of electric charges. 

Part 1

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 8:29am

Scientists uncover the structure of a bacterial toxin which injects itself into human cells and kills them

researchers have revealed the molecular structure of a cell-killing toxin produced by the bacterium Serratia marcescens.

S. marcescens is commonly involved in hospital-acquired infections – including respiratory diseases, bloodstream and urinary tract infections – and has developed resistance to many commonly used antibiotics.

Researchers discovered the toxin is able to inject itself into and kill a wide range of living cells, including in humans and livestock, insects, and plants.

The team determined the three-dimensional structure of Ssp using X-ray crystallography and identified a specific domain that promotes cell entry. It might also break down protein targets within the cell to cause its death – though more research is needed to confirm this.

The finding, published in Nature Communications, could lead to the development of new antimicrobial treatments and circumvent the use of antibiotics.

By understanding what Ssp looks like scientists can now develop targeted inhibitors.

These inhibitors or antimicrobials may be developed to bind to the part of Ssp responsible for injecting itself into cells.

https://www.nature.com/articles/s41467-023-36719-2

New inhibitors of the Ssp toxin, could be used to ‘disarm’ S. marcescens and reduce the sickness during infections. This would circumvent the use of antibiotics.

https://www.latrobe.edu.au/news/articles/2023/release/new-cell-kill...

Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 1:03pm

Yeast gains power to harness light

The first light-powered brewer’s yeast (Saccharomyces cerevisiae) has been engineered. “It is extraordinary,” says biologist Felipe Santiago-Tirado. “To some extent, it’s like turning an animal into a plant.” A protein called rhodopsin was artificially inserted into yeast cells, giving the fungus the ability to use light as an energy source for some of its cellular functions. Under green light, light-powered yeast cells reproduce fast enough to outgrow normal yeast.

https://www.biorxiv.org/content/10.1101/2022.12.06.519405v2

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AI-generated spam may soon be flooding your inbox—and it will be pe... Each day, messages from Nigerian princes, peddlers of wonder drugs and promoters of can't-miss investments choke email inboxes. Improvements to spam filters only seem to inspire new techniques to break through the protections.

Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 1:01pm

CAR-T Cells: Engineered Cancer Killers

Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 12:56pm

Earpiece that speeds up recovery after a stroke

researchers have developed a smart earpiece that helps people relearn physical actions faster and more easily after a stroke. By stimulating the brain, the earpiece helps it rewire neural circuits.

Strokes are the number one cause of persistent physical impairment among adults worldwide. Sufferers often find it hard or even impossible to perform everyday physical actions like walking or reaching for something. One reason for this is that the stroke has damaged regions in the brain involved in making the necessary movements.

Initial clinical studies conducted by other scientists have shown that stimulating the vagus nerve plays a crucial role in rehabilitating regions of the brain damaged by a stroke. Such stimulation has allowed stroke patients to regain their movement faster and more effectively.

But until now, this has required patients to undergo an expensive operation, performed under general anaesthetic, to implant a stimulation device below the skin. Since it’s common practice to wait a full year after a stroke to carry out this procedure, patients are losing valuable time.

Now,  researchers  from the Rehabilitation Engineering Laboratory have developed a new system that is set to make vagus nerve stimulation much easier and available much faster: Their earpiece emits subtle electrical impulses to activate the nerve in the outer ear, thus eliminating the need for a surgical procedure.

They ware able to show earlier that stimulating the vagus nerve wasn’t the only factor. The neuroscientist demonstrated that timing is also critical: the electrical impulses are particularly effective if administered while patients are attempting those motions that they have found difficult to perform since their stroke.

This helps the brain rewire motor neural circuits to compensate for malfunctions in regions damaged by the stroke. It’s like we’re reconfiguring the brain’s software: stimulating the nerve promotes neuroplasticity, aids the formation of new synapses and supports the relearning of physical actions.

What the researchers have done now is develop a movement sensor that works a bit like a smartwatch. Stroke patients wear this sensor wherever their motor function is impaired, for instance on their right arm. Using special software,  the sensor analyses the arm’s movements in real time and tells the earpiece when the patient moved their arm particularly well.

This triggers stimulation of the vagus nerve and the brain learns to recall the correct sequence of movements faster and more effectively. The technical term for this process is reinforcement learning.

Unlike previous treatment options, stroke patients can use the technology developed by the  researchers also without professional supervision. What’s more, the movement sensor will make it possible for physical therapists to monitor their patients’ progress conveniently using a smartphone. The  researchers expect this to yield further progress in treatment.

https://ethz.ch/en/news-and-events/eth-news/news/2023/04/earpiece-t...

Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 12:00pm

A gun that uses facial recognition can  reduce firearm deaths

 Kai Kloepfer is bringing his smart gun to market in what could be the first weapon to break a decades-old political and manufacturing "log jam" that has kept smart guns from mass production.

Kloepfer's Broomfield-based company, Biofire, on Thursday announced the sale of guns that use both fingerprint and facial recognition to make sure only authorized users can fire the weapon.

His goal is to reduce accidental deaths and suicides and to keep children from accessing their parents' weapons. The gun will allow people to have a weapon at hand but want to make sure children, visitors or criminals can't use it.

The gun is primarily marketed for use as a weapon for home defense, Kloepfer said. Gun owners must balance keeping a weapon easily accessible in case of emergency but also secure enough that others can't access it.

MediaNews Group, Inc.

https://techxplore.com/news/2023-04-gun-facial-recognition-firearm-...

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Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 11:40am

 Uses for Drones on the Farm 

Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 11:25am

Climate change may keep India from achieving its sustainable development goals

Heat waves in India are increasing in frequency, intensity and lethality, burdening public health, agriculture, and other socio-economic and cultural systems. A study published in PLOS Climate by  researchers suggests that heat waves made more likely by climate change may impede India's progress toward its sustainable development goals.

India has committed to achieving seventeen United Nations Sustainable Development Goals (SDG), including no poverty, good health and well being, and decent work and economic growth. However, current climate vulnerability assessments may not fully capture how heat waves linked to climate change may impact SDG progress. In order to analyze India's climate vulnerability, and how climate change may impact SDG progress, researchers conducted an analytical evaluation of India's heat index (HI) with its climate vulnerability index, (CVI) a composite index using various indicators to account for socioeconomic, livelihood, and biophysical factors.

They accessed a publicly available dataset on state-level climate vulnerability indicators from the Indian Government's National Data & Analytics Platform to classify severity categories. The researchers then compared India's progress in SDG over 20 years (2001–2021) with extreme weather-related mortality from 2001–2021. The researchers found that heat waves have weakened SDG progress more than previously estimated and that current assessment metrics may not sufficiently capture the nuances of India's vulnerabilities to climate change impacts. For instance, in estimating HI, the study shows that nearly 90% of the country is in danger zone from heat wave impacts.

According to the CVI, about 20% of the country is highly vulnerable to climate change. Similar effects were observed for the national capital, where HI estimates shows almost all of Delhi is threatened by severe heat wave impacts, which is not reflected in its recent state action plan for climate change. However, this study had several limitations, for example the incongruent timeframe for CVI data (2019–2020) and heat index data (2022). Future studies should incorporate more recent data. According to the authors, "This study shows that heat waves make more Indian states vulnerable to climate change than previously estimated with the CVI. The heat waves in India and the Indian subcontinent become recurrent and long-lasting, it is high time that climate experts and policymakers reevaluate the metrics for assessing the country's climate vulnerability. This offers a scope for developing a holistic vulnerability measure through international cooperation and partnership."

Heat waves are getting more intense in India, putting 80% of the country's people in danger, which remains unaccounted for in its current climate vulnerability assessment. If this impact is not addressed immediately, India can slow its progress towards sustainable development goals.

 Lethal heatwaves are challenging India's sustainable development, PLOS Climate (2023). DOI: 10.1371/journal.pclm.0000156

Comment by Dr. Krishna Kumari Challa on April 20, 2023 at 11:17am

Nanoparticles provoke immune response against tumors but avoid side effects

Cancer drugs that stimulate the body's immune system to attack tumors are a promising way to treat many types of cancer. However, some of these drugs produce too much systemic inflammation when delivered intravenously, making them harmful to use in patients.

Researchers have now come up with a possible way to get around that obstacle. In a new study, they showed that when immunostimulatory prodrugs—inactive drugs that require activation in the body—are tuned for optimal activation timing, the drugs provoke the immune system to attack tumors without the side effects that occur when the active form of the drug is given.

The researchers designed prodrugs with bottlebrush-like structures based on a class of compounds called imidazoquinolines (IMDs). Mice treated with these bottlebrush prodrugs designed with optimized activation kinetics showed a significant reduction in tumor growth, with no side effects. The researchers hope that this approach could be used to boost immune system responses in cancer patients, especially when combined with other immunotherapy drugs or cancer vaccines.

Sachin Bhagchandani et al, Engineering kinetics of TLR7/8 agonist release from bottlebrush prodrugs enables tumor-focused immune stimulation, Science Advances (2023). DOI: 10.1126/sciadv.adg2239. www.science.org/doi/10.1126/sciadv.adg2239

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