Record low sea ice cover in the Antarctic

 "On 8 February 2023, at 2.20 million square kilometres, the Antarctic sea ice extent had already dropped below the previous record minimum from 2022 (2.27 million square kilometres on 24 February 2022). Since the sea ice melting in the Antarctic will most likely continue in the second half of the month, we can't say yet when the record low will be reached or how much more sea ice will melt between now and then," says Prof Christian Haas, Head of the Sea Ice Physics Section at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), with regard to the current developments in the Antarctic. "The rapid decline in sea ice over the past six years is quite remarkable, since the ice cover hardly changed at all in the thirty-five years before. It is still unclear whether what we are seeing is the beginning of a rapid end to summer sea ice in the Antarctic, or if it is merely the beginning of a new phase characterised by low but still stable sea ice cover in the summer."

The melting has progressed since December 2022, especially in the Bellingshausen and Amundsen Seas in the West Antarctic; the former is virtually ice-free. That is also where the research vessel Polarstern currently is, exploring the evidence left behind of past glacials and interglacials. According to expedition leader and AWI geophysicist Prof Karsten Gohl, who is now in the region for the seventh time, having first come in 1994: "I have never seen such an extreme, ice-free situation here before. The continental shelf, an area the size of Germany, is now completely ice-free. Though these conditions are advantageous for our vessel-based fieldwork, it is still troubling to consider how quickly this change has taken place."

In the course of the year, the Antarctic sea ice generally reaches its maximum extent in September or October and its minimum extent in February. In some regions, the sea ice melts completely in summer. In winter, the cold climate throughout the Antarctic promotes the rapid formation of new sea ice. At its maximum, the sea ice cover in the Antarctic is generally between 18 and 20 million square kilometres. In summer, it dwindles to roughly 3 million square kilometres, displaying far more natural annual variability than ice in the Arctic.

source :science daily

New land creation on waterfronts increasing, study find

 

The study reports the first global assessment of coastal land reclamation, which is the process of building new land or filling in coastal water bodies, including wetlands, to expand a coastline. The researchers used satellite imagery to analyze land changes in 135 cities with populations of at least 1 million, 106 of which have done some coastline expansion.

The study was published in AGU's journal Earth's Future, which publishes interdisciplinary research on the past, present and future of our planet and its inhabitants.

"Population growth is not the only driver of coastal land reclamation," the study's authors said. "We expect that reclamation would continue to be popular in places that not only experience urban growth but also are eager to re-brand themselves for reputation and revenue."

Coastal land reclamation today is most common in the Global South, where many economies are rapidly growing. In the previous century and earlier, the Global North dominated the use of coastal land construction. The study found China, Indonesia and the United Arab Emirates added the most land area, with port extension being the most common reason for development. Shanghai alone has added about 350 square kilometers (135 square miles) of land. In the United States, by comparison, only Los Angeles has noticeably added land area in the last 20 years, with 0.29 square kilometers (0.1 square miles) built.

"It's quite important to capture this," said Robert Nicholls, who researches climate adaptation at the University of East Anglia and is not an author of the study. "There are more and more people, and our footprint is going up. Inevitably, there are ecologic consequences."

Lead author Dhritiraj Sengupta, a physical geographer at the University of Southampton, and his co-authors found that industrialization and a need for urban space have driven much coastal land reclamation, while a smaller proportion of expansion projects are for "prestige," such as the palm tree-shaped islands of Dubai.

About 70% of coastal land expansion has been carried out in low-lying regions that are likely to be exposed to extreme sea level rise by the end of the century. Both environmental impacts and projected coastal inundation suggest these developed coastlines are not sustainable, but cities will likely continue to build them, the authors said.

Some cities, including Shanghai, are building new land while considering future sea level rise, Sengupta said. However, selling a development as "green" is easier than selling it as an adaptation to sea level rise, he said. Evaluating the height of new land on a global scale is difficult. Doing so remains an interesting research question for scientists like Sengupta.

source: science daily

Fighting climate change: Ruthenium complexes for carbon dioxide reduction to valuable chemicals

 

On this front, scientists have suggested chemically converting CO2 into value-added compounds, such as methanol and formic acid (HCOOH). Producing the latter requires a source of hydride ion (H-), which is equivalent to one proton and two electrons. For instance, the nicotinamide adenine dinucleotide (NAD+/NADH) reduction-oxidation couple is a hydride (H-) generator and reservoir in biological systems.

Against this backdrop, a group of researchers led by Professor Hitoshi Tamiaki from Ritsumeikan University, Japan, have now developed a novel chemical method that reduces CO2 to HCOOH using NAD+/NADH-like ruthenium complexes. Their work was published in the journal ChemSusChem on 13 January 2023.

Prof. Tamiaki explains the motivation behind their research. "Recently, a ruthenium complex with an NAD+ model -- [Ru(bpy)2(pbn)](PF6)2 -- was shown to undergo photochemical two-electron reduction. It produced the corresponding NADH-type complex [Ru(bpy)2(pbnHH)](PF6)2 under visible light irradiation in the presence of triethanolamine in acetonitrile (CH3CN)," he elaborates. "Further, the bubbling of CO2 into the [Ru(bpy)2(pbnHH)]2+ solution regenerated [Ru(bpy)2(pbn)]2+ and produced formate ion (HCOO-). However, its yield was quite low. Therefore, transferring H- to CO2 required an improved catalytic system."

Consequently, the researchers explored various reagents and reaction conditions to facilitate CO2 reduction. Based on those experiments, they proposed a photoinduced two-electron reduction of the [Ru(bpy)2(pbn)]2+/[Ru(bpy)2(pbnHH)]2+ redox couple in the presence of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH). Moreover, water (H2O), instead of triethanolamine, in CH3CN further improved the yield.

In addition, the researchers explored the underlying reaction mechanism using techniques like nuclear magnetic resonance, cyclic voltammetry, and UV-Vis spectrophotometry. Based on this, they proposed the following: First, the photo-excitation of [Ru(bpy)2(pbn)]2+ produces [RuIII(bpy)2(pbn•?)]2+* radical, which undergoes reduction by BIH to give [RuII(bpy)2(pbn•?)]2+ and BIH•+. Following this, H2O protonates the ruthenium complex, generating [Ru(bpy)2(pbnH•)]2+ and BI•. The obtained product undergoes disproportionation to generate [Ru(bpy)2(pbnHH)]2+ and gives back [Ru(bpy)2(pbn)]2+. Then, the former is reduced by BI• to produce [Ru(bpy)(bpy•?)(pbnHH)]+. This complex is an active catalyst and transfers H- to CO2, producing HCOO- and formic acid.

The researchers showed that the proposed reaction demonstrated a high turnover number -- moles of CO2 converted by a mole of catalyst -- of 63.

Excited by these findings, the researchers hope to develop a new methodology of energy conversion (sunlight to chemical energy) for the production of novel renewable materials.

"Our method would also decrease the total amount of CO2 gas on Earth and help maintain the carbon cycle. Thus, it could reduce global warming in the future," adds Prof. Tamiaki. "Further, the novel organic hydride transfer technology will provide us with invaluable chemical compounds."

source: science daily

Traffic pollution impairs brain function

 A new study by researchers at the University of British Columbia and the University of Victoria has shown that common levels of traffic pollution can impair human brain function in only a matter of hours.

The peer-reviewed findings, published in the journal Environmental Health, show that just two hours of exposure to diesel exhaust causes a decrease in the brain's functional connectivity -- a measure of how The study provides the first evidence in humans, from a controlled experiment, of altered brain network connectivity induced by air pollution.

"For many decades, scientists thought the brain may be protected from the harmful effects of air pollution," said senior study author Dr. Chris Carlsten, professor and head of respiratory medicine and the Canada Research Chair in occupational and environmental lung disease at UBC. "This study, which is the first of its kind in the world, provides fresh evidence supporting a connection between air pollution and cognition."

For the study, the researchers briefly exposed 25 healthy adults to diesel exhaust and filtered air at different times in a laboratory setting. Brain activity was measured before and after each exposure using functional magnetic resonance imaging (fMRI).

The researchers analyzed changes in the brain's default mode network (DMN), a set of inter-connected brain regions that play an important role in memory and internal thought. The fMRI revealed that participants had decreased functional connectivity in widespread regions of the DMN after exposure to diesel exhaust, compared to filtered air.

"We know that altered functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, so it's concerning to see traffic pollution interrupting these same networks," said Dr. Jodie Gawryluk, a psychology professor at the University of Victoria and the study's first author. "While more research is needed to fully understand the functional impacts of these changes, it's possible that they may impair people's thinking or ability to work."

Taking steps to protect yourself

Notably, the changes in the brain were temporary and participants' connectivity returned to normal after the exposure. Dr. Carlsten speculated that the effects could be long lasting where exposure is continuous. He said that people should be mindful of the air they're breathing and take appropriate steps to minimize their exposure to potentially harmful air pollutants like car exhaust.

"People may want to think twice the next time they're stuck in traffic with the windows rolled down," said Dr. Carlsten. "It's important to ensure that your car's air filter is in good working order, and if you're walking or biking down a busy street, consider diverting to a less busy route."

While the current study only looked at the cognitive impacts of traffic-derived pollution, Dr. Carlsten said that other products of combustion are likely a concern.

"Air pollution is now recognized as the largest environmental threat to human health and we are increasingly seeing the impacts across all major organ systems," says Dr. Carlsten. "I expect we would see similar impacts on the brain from exposure to other air pollutants, like forest fire smoke. With the increasing incidence of neurocognitive disorders, it's an important consideration for public health officials and policymakers."

The study was conducted at UBC's Air Pollution Exposure Laboratory, located at Vancouver General Hospital, which is equipped with a state-of-the-art exposure booth that can mimic what it is like to breathe a variety of air pollutants. In this study, which was carefully designed and approved for safety, the researchers used freshly-generated exhaust that was diluted and aged to reflect real-world conditions.

Source: ScienceDaily

Reducing total calories may be more effective for weight loss than intermittent fasting

 The frequency and size of meals was a stronger determinant of weight loss or gain than the time between first and last meal, according to new research published today in the Journal of the American Heart Association, an open access, peer-reviewed journal of the American Heart Association.

According to the senior study author Wendy L. Bennett, M.D., M.P.H., an associate professor of medicine at Johns Hopkins University School of Medicine in Baltimore, although 'time-restricted eating patterns' -- known as intermittent fasting -- are popular, rigorously designed studies have not yet determined whether limiting the total eating window during the day helps to control weight.

This study evaluated the association between time from the first meal to last meal with weight change. Nearly 550 adults (18 years old or older) from three health systems in Maryland and Pennsylvania with electronic health records were enrolled in the study. Participants had at least one weight and height measurement registered in the two years prior to the study's enrollment period (Feb.-July 2019).

Overall, most participants (80%) reported they were white adults; 12% self-reported as Black adults; and about 3% self-identified as Asian adults. Most participants reported having a college education or higher; the average age was 51 years; and the average body mass index was 30.8, which is considered obese. The average follow-up time for weight recorded in the electronic health record was 6.3 years.

Participants with a higher body mass index at enrollment were more likely to be Black adults, older, have Type 2 diabetes or high blood pressure, have a lower education level, exercise less, eat fewer fruits and vegetables, have a longer duration from last mealtime to sleep and a shorter duration from first to last meal, compared to the adults who had a lower body mass index.

The research team created a mobile application, Daily24, for participants to catalog sleeping, eating and wake up time for each 24-hour window in real time. Emails, text messages and in-app notifications encouraged participants to use the app as much as possible during the first month and again during "power weeks" -- one week per month for the six-month intervention portion of the study.

Based on the timing of sleeping and eating each day recorded in the mobile app, researchers were able to measure:

• the time from the first meal to the last meal each day;
• the time lapse from waking to first meal; and
• the interval from the last meal to sleep.

They calculated an average for all data from completed days for each participant.

The data analysis found:

• Meal timing was not associated with weight change during the six-year follow-up period. This includes the interval from first to last meal, from waking up to eating a first meal, from eating the last meal to going to sleep and total sleep duration.
• Total daily number of large meals (estimated at more than 1,000 calories) and medium meals (estimated at 500-1,000 calories) were each associated with increased weight over the six-year follow up, while fewer small meals (estimated at less than 500 calories) was associated with decreasing weight.
• The average time from first to last meal was 11.5 hours; average time from wake up to first meal measured 1.6 hours; average time from last meal to sleep was 4 hours; and average sleep duration was calculated at 7.5 hours.
• The study did not detect an association meal timing and weight change in a population with a wide range of body weight.

As reported by Bennett, even though prior studies have suggested intermittent fasting may improve the body's rhythms and regulate metabolism, this study in a large group with a wide range of body weights did not detect this link. Large-scale, rigorous clinical trials of intermittent fasting on long-term weight change are extremely difficult to conduct; however, even short-term intervention studies may be valuable to help guide future recommendations.

Although the study found that meal frequency and total calorie intake were stronger risk factors for weight change than meal timing, the findings could not prove direct cause and effect, according to lead study author Di Zhao, Ph.D., an associate scientist in the division of cardiovascular and clinical epidemiology at Johns Hopkins Bloomberg School of Public Health.

Source: ScienceDaily

Artificial human skin paves the way to new skin cancer therapy

 By using artificial human skin, a research group from the University of Copenhagen have managed to block invasive growth in a skin cancer model.

The study has been published in Science Signaling and looks at what actually happens when a cell turns into a cancer cell.

"We have been studying one of the cells' signalling pathways, the so-called TGF beta pathway. This pathway plays a critical role in the cell's communication with its surroundings, and it controls e.g. cell growth and cell division. If these mechanisms are damaged, the cell may turn into a cancer cell and invade the surrounding tissue," explains Professor and Team Lead Hans Wandall from the Department of Cellular and Molecular Medicine at the University of Copenhagen.

Under normal circumstances, your skin cells will not just start to invade the hypodermis and wreak havoc. Instead, they will produce a new layer of skin. But when cancer cells emerge, the cells no longer respect the boundaries between skin layers, and they start to invade each other. This is called invasive growth.

Hans Wandall and his colleagues have been studying the TGF beta pathway and applied methods for blocking invasive growth and thus curbing the invasive growth in skin cancer.

"We already have various drugs that can block these signalling pathways and which may be used in tests. We have used some of them in this study," explains Associate Professor and co-author of the study Sally Dabelsteen from the School of Dentistry.

Hans Wandall and Sally Dabelsteen have worked together with Dr. Zilu Ye and Professor Jesper V. Olsen from the Novo Nordisk Foundation Center for Protein Research at the Faculty of Health and Medical Sciences.

"Some of these drugs have already been tested on humans, and some are in the process of being tested in connection with other types of cancer. They could also be tested on skin cancer specifically," she says.

Artificial skin is the closest we get to real human skin

The artificial skin used by the researchers in the new study consists of artificial, genetically manipulated human skin cells. Skin cells are produced on subcutaneous tissue made of collagen. This makes the cells grow in layers, just like real human skin.

Unlike mice models, the skin model, which is another word for artificial skin, allows researchers to introduce artificial genetic changes relatively quickly, which provide insight into the systems that support skin development and renewal.

This way they are also able to reproduce and follow the development of other skin disorders, not just skin cancer.

"By using artificial human skin we are past the potentially problematic obstacle of whether results from tests on mice models can be transferred to human tissue. Previously, we used mice models in most studies of this kind. Instead, we can now conclude that these substances probably are not harmful and could work in practice, because the artificial skin means that we are closer to human reality," says Hans Wandall.

The artificial skin used by the researchers resembles the skin used to test cosmetics in the EU, which banned animal testing in 2004. However, artificial skin does not allow the researchers to test the effect of a drug on the entire organism, Hans Wandall points out. Skin models like the one used here have been used by cosmetics companies since the mid-1980s.

Source: ScienceDaily

Coffee with milk may have an anti-inflammatory effect

 Can something as simple as a cup of coffee with milk have an anti-inflammatory effect in humans? Apparently so, according to a new study from the University of Copenhagen. A combination of proteins and antioxidants doubles the anti-inflammatory properties in immune cells. The researchers hope to be able to study the health effects on humans.

Whenever bacteria, viruses and other foreign substances enter the body, our immune systems react by deploying white blood cells and chemical substances to protect us. This reaction, commonly known as inflammation, also occurs whenever we overload tendons and muscles and is characteristic of diseases like rheumatoid arthritis.

Antioxidants known as polyphenols are found in humans, plants, fruits and vegetables. This group of antioxidants is also used by the food industry to slow the oxidation and deterioration of food quality and thereby avoid off flavors and rancidity. Polyphenols are also known to be healthy for humans, as they help reduce oxidative stress in the body that gives rise to inflammation.

But much remains unknown about polyphenols. Relatively few studies have investigated what happens when polyphenols react with other molecules, such as proteins mixed into foods that we then consume.

In a new study, researchers at the Department of Food Science, in collaboration with researchers from the Department of Veterinary and Animal Sciences, at University of Copenhagen investigated how polyphenols behave when combined with amino acids, the building blocks of proteins. The results have been promising.

"In the study, we show that as a polyphenol reacts with an amino acid, its inhibitory effect on inflammation in immune cells is enhanced. As such, it is clearly imaginable that this cocktail could also have a beneficial effect on inflammation in humans. We will now investigate further, initially in animals. After that, we hope to receive research funding which will allow us to study the effect in humans," says Professor Marianne Nissen Lund from the Department of Food Science, who headed the study.

The study has just been published in the Journal of Agricultural and Food Chemistry.

Twice as good at fighting inflammation

To investigate the anti-inflammatory effect of combining polyphenols with proteins, the researchers applied artificial inflammation to immune cells. Some of the cells received various doses of polyphenols that had reacted with an amino acid, while others only received polyphenols in the same doses. A control group received nothing.

The researchers observed that immune cells treated with the combination of polyphenols and amino acids were twice as effective at fighting inflammation as the cells to which only polyphenols were added.

"It is interesting to have now observed the anti-inflammatory effect in cell experiments. And obviously, this has only made us more interested in understanding these health effects in greater detail. So, the next step will be to study the effects in animals," says Associate Professor Andrew Williams of the Department of Veterinary and Animal Sciences at the Faculty of Health and Medical Sciences, who is also senior author of the study.

Found in coffee with milk

Previous studies by the researchers demonstrated that polyphenols bind to proteins in meat products, milk and beer. In another new study they tested whether the molecules also bind to each other in a coffee drink with milk. Indeed, coffee beans are filled with polyphenols, while milk is rich in proteins.

"Our result demonstrates that the reaction between polyphenols and proteins also happens in some of the coffee drinks with milk that we studied. In fact, the reaction happens so quickly that it has been difficult to avoid in any of the foods that we've studied so far," says Marianne Nissen Lund.

Source: ScienceDaily