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Comment by Dr. Krishna Kumari Challa on December 12, 2023 at 9:50am

Biocrusts on Great Wall of China found to be protecting it from erosion

A small international team of soil and water ecosystem conservation specialists has found that biocrusts clinging to parts of the Great Wall of China have been serving to protect the famous structure from erosion. In their paper published in the journal Science Advances (1), the group describes their study and analysis of material growing on the wall.

The Great Wall of China was built over several centuries starting approximately 221 BC—its function was to protect the people living behind it from enemies attempting to invade from the other side. Prior research has shown that different parts of the wall were made with different materials—mostly rammed earth or stone.

Rammed earth is made by mixing organic materials with inorganic materials. Because of their nature, such materials are more susceptible to erosion. That has led to questions regarding how sections of the wall made with the material have survived for so many years. In this new effort, the researchers wondered if perhaps biocrusts may have played a role.

For many years, scientists have assumed that such biocrusts, which are generally made of cyanobacteria, lichen and mosses, speed up the erosion process. To find out if that is the case, the research team collected samples of the biocrusts from several points along the wall and brought them back to a lab for study.

The researchers measured the mechanical strength and soil stability of the samples. They also tested parts of the wall directly comparing those covered in biocrusts and those that were directly exposed to the elements.

They found that the biocrusts were stronger than the rammed earth material upon which they were growing—in some cases, three times as strong. The researchers also found the strength in the biocrusts was due to secretion of tightly bound polymers.

The research team concluded that rather than speeding up erosion, the biocrusts have been slowing the process, helping to preserve the famed structure. Somewhat analogous to their findings were those by a team from the University of Granada working in Honduras that found that organic plant materials added to plasters by early Mayan people have served to reduce weathering of the stone structures they built(2). 

Footnotes:

1.Yousong Cao et al, Biocrusts protect the Great Wall of China from erosion, Science Advances (2023). DOI: 10.1126/sciadv.adk5892

2. Carlos Rodriguez-Navarro et al, Unveiling the secret of ancient Maya masons: Biomimetic lime plasters with plant extracts, Science Advances (2023). DOI: 10.1126/sciadv.adf6138

Comment by Dr. Krishna Kumari Challa on December 10, 2023 at 1:50pm

Modelling the effects of this pulse through the Earth System shows that this new, suddenly disrupted, climate pattern is here for at least 50,000 years and probably far longer. It's a large part of the way our planet has changed fundamentally and irreversibly, to become comparable to some of the great climate change events in deep Earth history.

So will this particular COP meeting, with fossil fuel interests so strongly represented, make a difference? The bottom line is that attaining, and stabilising carbon emissions at "net zero" is only a crucial first step.

This latest warming step has already taken the Earth into levels of climate warmth not experienced for some 120,000 years, into those of the last interglacial phase, a little warmer than the current one. There is yet more warming in the pipeline over coming centuries, as various feedbacks take effect. A recent study on the effects of this warming on Antarctica's ice suggests that "policymakers should be prepared for several metres of sea-level rise over the coming centuries" as the pulse of warmth spreads through the oceans to undermine the great polar ice-sheets.

https://theconversation.com/the-climate-change-we-caused-is-here-fo...

Part 2

Comment by Dr. Krishna Kumari Challa on December 10, 2023 at 1:48pm

The Climate Change We've Already Created Will Last 50,000 Years, Scientists Warn

The idea of an entirely new and human-created geological epoch is a sobering scenario as context for the current UN climate summit, COP28. The impact of decisions made at these and other similar conferences will be felt not just beyond our own lives and those of our children, but perhaps beyond the life of human society as we know it.

Enormous deforestation, the mushrooming of dams across the world's large rivers, overfishing, a planet's nitrogen cycle overwhelmed by fertiliser use, the rapid rise in greenhouse gases.....

As for climate change itself, well, the warning bells were ringing, certainly. Global mean surface temperatures had risen by about half a degree since the mid-20th century. But, they were still within the norm for an interglacial phase of the ice ages. Among many emerging problems, climate seemed one for the future.

A little more than two decades on, the future has arrived. By 2022, global temperature had climbed another half a degree, the past nine years being the hottest since records began. And 2023 has seen climate records being not just broken, but smashed.

With this leap in temperatures came record-breaking heatwaves, wildfires and floods, exacerbated by other local human actions. Climate has moved centre stage on an Anthropocene Earth.

To see how this might play out on a geological timescale, we need to look through the lens of the Anthropocene. A delicately balanced planetary machinery of regular, multi-millennial variations in the Earth's spin and orbit has tightly controlled patterns of warm and cold for millions of years.

Now, suddenly, this control machinery has been overridden by a trillion tons of carbon dioxide injected into the atmosphere in little more than a century.

Part 1

Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 11:31am

‘Tweezers’ hold quantum molecule
Physicists have used lasers as ‘optical tweezers’ to position molecules so precisely that the molecules can be used as qubits to process quantum information. Pairs of calcium monofluoride molecules were gingerly manoeuvred so that they became entangled and behaved as a single collective quantum system. The molecules were cooled to close to absolute zero, making them almost completely still. When their rotation was completely stopped, they represented the ‘0’ state of the qubit. Meanwhile, molecules allowed to rotate with just one quantum of rotational momentum represented the ‘1’ state. Molecules have some advantages over other qubit candidates, such as atoms. For example, molecules could be pushed into service as ‘qutrits’, which have three possible states: −1, 0 and +1.

https://www.science.org/doi/10.1126/science.adf8999

https://www.science.org/doi/10.1126/science.adf4272

Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 10:35am

Catalyst makes drugs inside the body to minimize side effects

A highly active catalyst capable of synthesizing drug molecules within the body has been developed by  chemists. In mice, an anticancer drug assembled near tumors using the injected catalyst suppressed tumour growth.

In conventional medicines delivered by injection or pill, the active drug molecule circulates throughout the body, flooding not only the target site but also healthy tissues. The resulting side effects can be so serious that they can cause permanent damage and force treatment to be stopped. Assembling drug molecules at target sites within the body could make them more effective while minimizing their side effects.

The direct synthesis of drugs in the body would enable drugs to treat diseases without causing side effects in healthy tissues. That's why we need a biocompatible biocatalysis system to perform drug synthesis near target sites in the body.

The team targeted drug assembly in the body using a catalytic chemical reaction called olefin metathesis. Olefin metathesis is one of the most efficient methods for constructing carbon–carbon double bonds for synthesizing drugs. If it could be worked out in the body, it should enable us to synthesize many different types of drugs.

Most chemical catalysts are rapidly deactivated by biomolecules in the bloodstream. To overcome this problem, the team wrapped a ruthenium-based olefin metathesis catalyst inside a protective protein called human serum albumin.

Tanaka's team had previously shown that a ruthenium chloride complex embedded inside human serum albumin—forming a catalytic assembly called an artificial metalloenzyme—was somewhat active in blood. Now, they have shown that switching to a ruthenium iodide complex produces a far superior artificial metalloenzyme.

At low catalyst concentrations, the new albumin-based ruthenium iodide (AlbRuI) catalyst catalyzed three types of olefin metathesis reactions in blood at high yield.

AlbRuI also showed robust stability for 24 hours in blood.This expands the biocompatibility of artificial metalloenzymes and opens the door for developing general, metal-based artificial metalloenzymes for catalytic reactions in blood.

The team also showed that a low dose of cancer-targeting AlbRuI significantly inhibited tumour growth in mice through localized synthesis of an antitumour drug.

 Igor Nasibullin et al, Catalytic olefin metathesis in blood, Chemical Science (2023). DOI: 10.1039/D3SC03785A

Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 10:27am

Rich nations need to ditch fossil fuels by 2040: scientists

Rich countries need to stop using coal by 2030 and oil and gas by 2040, with poorer nations following a decade behind, to give the world a chance of limiting warming to 1.5C, climate scientists told the UN this week.

In a note to the UN Secretary-General Antonio Guterres and UN Climate Change body, shared with AFP, climate scientists said there was very little room for anything but a total phase-out of fossil fuels.

The steep timeline they laid out comes as climate negotiators at the COP28 talks in Dubai are tussling over the future of oil, gas and coal, responsible for the lion's share of humanity's planet-heating emissions.

The UN climate negotiations are tasked with helping the world meet the Paris deal goal of limiting global warming to 1.5 degrees Celsius from pre-industrial levels, but have often been vague on how that target will be achieved.

The discussions should be around serious and fair efforts to start implementing a phase out plan: scientists

Source: AFP

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Israel's AI can produce 100 bombing targets a day in Gaza. Is this ...

Last week, reports emerged that the Israel Defense Forces (IDF) are using an artificial intelligence (AI) system called Habsora (Hebrew for "The Gospel") to select targets in the war on Hamas in Gaza. The system has reportedly been used to find more targets for bombing, to link locations to Hamas operatives, and to estimate likely numbers of civilian deaths in advance.

https://theconversation.com/israels-ai-can-produce-100-bombing-targ...

Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 10:05am

Credit: Molecular Cell (2023). DOI: 10.1016/j.molcel.2023.10.036

Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 10:03am

Researchers discover a mechanism that controls the identity of stem cells

Researchers  discovered a mechanism that controls the identity of stem cells. When this mechanism fails, embryonic stem cells revert back in time and become totipotent (totipotent embryo cells can differentiate into a hundred different cell types specialized to form such tissues as skin, marrow, and muscle).

When a cell becomes totipotent, this rare change enables the cells to differentiate into hundreds of cell types, and then go on to form every part of our body. This contrasts with pluripotent stem cells, which can divide into various cell types but are unable to become an entire organism solely on their own.

In a dish of embryonic stem cells, the majority of stem cells are pluripotent. However, 1 out of 1,000 cells are different from the rest, and are totipotent. Totipotent cells are the only cells that have unlimited potential and can give rise to all parts of our body. Scientists now discovered the mechanism that allows this change from pluripotent to totipotent.

Denis Torre et al, Nuclear RNA catabolism controls endogenous retroviruses, gene expression asymmetry, and dedifferentiation, Molecular Cell (2023). DOI: 10.1016/j.molcel.2023.10.036

Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 9:58am

In genetics, the concept of pleiotropy posits that a single mutation can influence multiple traits. The idea that the same mutation can be both beneficial and harmful, depending on the situation, is known as antagonistic pleiotropy and was proposed by Williams to underlie the origin of aging in a paper titled "Pleiotropy, natural selection, and the evolution of senescence."

To a biologist, senescence refers specifically to a gradual decline of bodily functions that manifests as a decline in reproductive performance and an increase in the death rate with age.

Compared with environmental factors, genetic factors play a minor role in the human phenotypic changes studied here.

Erping Long et al, Evidence for the role of selection for reproductively advantageous alleles in human aging, Science Advances (2023). DOI: 10.1126/sciadv.adh4990. www.science.org/doi/10.1126/sciadv.adh4990

Part 2

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Comment by Dr. Krishna Kumari Challa on December 9, 2023 at 9:56am

Genetic mutations that promote reproduction tend to shorten human lifespan, study shows

A  study based on a review of genetic and health information from more than 276,000 people finds strong support for a decades-old evolutionary theory that sought to explain aging and senescence.

In 1957, evolutionary biologist George Williams proposed that genetic mutations that contribute to aging could be favored by natural selection if they are advantageous early in life in promoting earlier reproduction or the production of more offspring.

Now known as the antagonistic pleiotropy theory of aging, remains the prevailing evolutionary explanation of senescence, the process of becoming old or aging. 

This theory was tested now. 

The researchers found reproduction and lifespan to be genetically strongly negatively correlated, meaning that genetic mutations that promote reproduction tend to shorten lifespan.

In addition, individuals carrying mutations that predispose them to relatively high reproductive rates have lower probabilities of living to age 76 than those carrying mutations that predispose them to relatively low reproductive rates, according to the study.

However, the authors caution that reproduction and lifespan are affected by both genes and the environment. And compared with environmental factors—including the impacts of contraception and abortion on reproduction and medical advances on lifespan—the genetic factors discussed in the study play a relatively minor role, according to the authors. These results provide strong support for the Williams hypothesis that aging arises as a byproduct of natural selection for earlier and more reproduction. Natural selection cares little about how long we live after the completion of reproduction, because our fitness is largely set by the end of reproduction.

Fitness is a concept biologists use to describe the degree to which an organism's characteristics increase its number of offspring.

The researchers now  found that when you control for the genetically predicted amount and timing of reproduction, having two kids corresponds to the longest lifespan. Having fewer or more kids both lower the lifespan. That result supports the findings of several previous studies.

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