Cancer Survivors’ Tongues Less Sensitive To Tastes Than Those of Healthy Peers (Medicine)

Most survivors of squamous cell head and neck cancers report that their sense of taste is dulled, changed or lost during radiation treatment, causing them to lose interest in eating and diminishing their quality of life.

In a study of taste and smell dysfunction with 40 cancer survivors, scientists at the University of Illinois Urbana-Champaign found that the tips of these individuals’ tongues were significantly less sensitive to bitter, salty or sweet tastes than peers in the control group who had never been diagnosed with cancer.

In a paper published in the journal Chemical Senses, the U. of I. team said this diminished taste sensitivity suggested that the taste buds on the front two-thirds of the cancer survivors’ tongues or a branch of the chorda tympani facial nerve, which carries signals from the tip of the tongue to the brain, may have been damaged during radiation therapy.

“While most studies suggest that patients’ ability to taste recovers within a few months of treatment, patients report that they continue to experience taste dysfunction for years after treatment ends,” said M. Yanina Pepino, a professor of food science and human nutrition at the U. of I. “Our primary goal in this study was to test the hypothesis that radiation therapy is associated with long-term alterations in patients’ senses of smell and taste.”

Graduate student Raul Alfaro
Graduate student Raul Alfaro was the first author of the study, published in the journal Chemical Senses. © Photo by Audra E. Martin

While undergoing radiation and/or chemotherapy, head and neck cancer patients may lose taste buds, triggering a transient reduction in their ability to taste – a condition called hypogeusia – or their perception of tastes may be altered, a condition called dysgeusia that can also occur when nerves are damaged during cancer surgery, she said.

“Taste buds’ average lifespan of about 10 days enables rapid recovery from injury if the stem cells are preserved, yet it also makes the short-lived and long-lived cells within taste buds particularly vulnerable to the direct cytotoxic and anti-proliferative effects of chemotherapy and radiotherapy,” Pepino said.

Prior studies that explored taste loss and perception in these patients showed mixed results. Many of these studies involved “whole mouth” experiments that may not have detected regional damage to the taste buds at the front of the tongue or to the chorda tympani section of the facial nerve, said graduate student Raul Alfaro, the lead author of the study.

The U. of I. team assessed participants’ smell and taste functions separately and explored whether sensory interactions between taste and retronasal odors – aromas from food and beverages that are perceived in the oral cavity while eating or drinking – differed for the cancer survivors and the people in the control group.

 The team assessed participants’ ability to taste regionally by applying cotton swabs soaked in flavored solutions to the tips of their tongues.

They also evaluated participants’ whole-mouth taste function by having them swish solutions around in their mouths for five seconds and spit them out. For this test, the participants were presented with nine cups of liquids that contained both taste and smell sensory components. The cups contained two concentrations of strawberry extract in a sucrose solution, lemon extract in citric acid, salt in a vegetable broth and caffeinated instant coffee. They also received one cup of deionized water.

After sipping each sample, participants were asked to identify its taste quality – sweet, salty, bitter, umami (savory) or no sensation – and to rate the smell and taste intensity of the sample on a scale that ranged from “no sensation” to “strongest of any kind.”

Food science and human nutrition professor Anna E. Arthur and then-research fellow Sylvia L. Crowder seated at a table
Food science and human nutrition professor Anna E. Arthur and then-research fellow Sylvia L. Crowder were co-authors of the study. © Photo by L. Brian Stauffer

Participants tasted the samples twice – once wearing a nose clip and once without – to determine whether their taste perception differed when the nose clip blocked their retronasal olfactory cues.

When participants’ sense of taste was assessed using the whole-mouth test with or without the nose clip, they similarly rated the taste and smell of nearly all of the samples.

However, when participants’ sense of taste was assessed regionally at the tip of the tongue, the cancer survivors were more likely to respond they did not perceive a taste or to misidentify the taste quality – such as bitter, salty or sweet – of multiple samples.

“Although the results from the whole-mouth taste test suggested that head and neck cancer survivors’ taste function was normal and well preserved, results from the regional tests indicated that they had some deficits,” Pepino said. “Subtle taste dysfunction in the tip of the tongue persisted for several months after they completed their oncology treatments.

“Taste dysfunction at the tip of the tongue might sound unimportant; however, there is an elegant cross-talk between the nerves that conveys signals from the tip and the back of the tongue, such that taste signals in the tip of the tongue inhibit signaling from the back. This system allows taste intensity to remain constant in the whole mouth, even when taste signaling coming from the tip of the tongue is reduced. However, reduced signal input can also lead to phantom tastes, metallic taste and other oral symptoms.” 

Additional co-authors of the study were food science and human nutrition professor Anna E. Arthur, who is also the Sylvia D. Stroup Scholar in Nutrition and Cancer, and an oncology dietitian with the Carle Cancer Center; Dr. Kalika P. Sarma, a radiation oncologist at Carle Foundation Hospital and a clinical assistant professor in the Carle Illinois College of Medicine; and then-research fellow Sylvia L. Crowder.

The work was supported by grants from the U.S. Department of Agriculture National Institute of Food and Agriculture, the Academy of Nutrition and Dietetics, and the Division of Nutritional Sciences at the U. of I.

Crowder’s work on the project was supported by a Carle Illinois Cancer Scholars for Translational and Applied Research Fellowship, as well as a grant from the National Cancer Institute.

The paper “Taste and smell function in head and neck cancer survivors” is available from the News Bureau. DOI: 10.1093/chemse/bjab026

Featured image: Head and neck cancer survivors’ tongues are less sensitive at the tip, and problems with taste dysfunction may persist for years after patients complete oncology treatments, a team led by food science and human nutrition professor M. Yanina Pepino found in a study. © Photo by Luka Gruev

Provided by University of Illinois

Powerful People are Less Likely to be Understanding When Mistakes are Made (Psychology)

Those with privilege are less aware of constraints others face and are more likely to punish subordinates, according to new UC San Diego research

Those with power, such as the wealthy are more likely to blame others for having shortcomings and they are also less troubled by reports of inequality, according to recent research from the University of California San Diego’s Rady School of Management.

The study published in Social Psychological and Personality Science defines power as control over valuable resources. The paper finds that people in positions of power are more likely to adopt  a “choice-mindset,” which means that although they have more choices (the definition of power in many cases) they still see others with less power as having lots of choice, regardless of their situation. Consequently, high-power individuals are more likely to blame others if they perform poorly and they are also more likely to punish them.

“Being in a choice-mindset changes how individuals think, feel and behave,” said Yidan Yin, the first author of the paper and recent PhD graduate from the Rady School. “Compared to low-power people, high-power people are less likely to be aware of others’ constraints. As a result they assign more blame when people make mistakes or have shortcomings. Thus, they see the current hierarchy as more justified.”

The results from the research were derived from three different studies the authors conducted to replicate the findings in different settings.

Research findings hold up in three robust study settings

The first study was conducted via a survey in which the researchers measured the sense of power of 363 members of the general public recruited through the platform Prolific. They also asked the participants to complete a separate survey, claiming it was unrelated, in which they were crowdsourcing how to resolve a human resources issue at the university. The survey explained that their academic department was weighing whether to give an administrative assistant a bonus though they had missed a deadline on a big project due to conflicting priorities. The survey participants who measured as having a greater sense of power overwhelming responded the administrative assistant did not deserve the bonus and that their excuses were without merit.

The second study was conducted with the platform Amazon Mechanical Turk involving 393 members of the general public who were randomly assigned to roles as supervisors and subordinates in completing various tasks. Though the assigned ranks were random, supervisors were told they earned the role for their proficiencies and subordinates were told they were designated as such because they were outperformed by supervisors.

The two groups had to judge the performance of an anonymous individual, who by design, made mistakes in completing their tasks. Once again, the researchers found that those with a greater sense of power (supervisors) were harsher, less understanding with their judgment and recommended punishment more than subordinates.

The third study was done in a lab with UC San Diego undergraduates and mirrored the second experiment. The main difference was that both supervisors and subordinates knew that the target person they had to judge had the rank of a subordinate and therefore less choices. The results from the first two studies held up with subjects that had more power assigning more blame and recommending more punishment.

“Each study was designed to build on the others,” Yidan and co-author Pamela K. Smith, associate professor of economics and strategic management at the Rady School write. “In study one, we were measuring power, in study two, we manipulated power and in study three, we created a world in which the judges knew the target person had less power and less choices. We wanted to see if the perceptions remained consistent in all three settings.  It was a combination of replication and adding these additional twists and turns.”

Implications for more equitable public policy and workplace environments

The results from the study have significant implications for public policy, according to the authors.

“Policymakers are in a position of power and privilege and may be less sensitive to the disadvantages of their constituents,” the authors write. “This is especially important as we come out of the pandemic when there are big discussions in the political domain on pulling back on unemployment benefits, or rent assistance. If you are in a position of power, you may assume people are choosing to stay home and not work and they can make better choices. However, you may need to think much more carefully about how many choices citizens have and if you are missing constraints they face.”

In addition, the implications are far-reaching for the workplace.

“Mangers should be aware of how many more choices they have than their subordinates and their tendency to project their own choices onto others, especially when employees make mistakes.” Yin said.

Smith added, “It might require having more discussion with employees and being cognizant of their situation because sometimes lack of choice and constraints can be invisible to someone from the outside.”

The Power Increases Perceptions of Others’ Choices, Leading People to Blame Others More paper was also co-authored by Krishna Savani of Nanyang Technological University.

Featured image: People in positions of power are more likely to adopt a “choice-mindset,” which means that although they have more choices they still see others with less power as having lots of choice, regardless of their situation. Credit: AndreyPopov/iStock

Provided by UC San Diego

Threatened by the Sun’s Superflare? LAMOST and TESS Help to Find the Answer (Planetary Science)

Superflare is an energetic stellar activity, whose explosion energy can be more than ten thousand times that of a typical solar flare. They erupt tremendous energies in just hour-scale duration, which will definitely ruin the planetary system nearby.  

A research team led by Prof. WANG Fayin from Nanjing University, cooperating with Dr. WANG Haifeng from Yunnan University, used the photometric data from TESS and the spectroscopic data from LAMOST to explore superflares on solar-type stars, whose surface temperature and gravity are similar to that of the Sun. 

The researchers found that a single solar-type star is capable to generate superflares, however, the Sun might not generate superflare due to generally lower chromospheric activity compared with other solar-type stars.  

The results were published in The Astrophysical Journal Supplement Series.  

Since July 2019, TESS began its 2nd year mission to observe the northern hemisphere of the sky, while LAMOST has been spectroscopically observing since 2012. They provide powerful data support for the study on stellar superflares.

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope, or LAMOST for short, is operated by the National Astronomical Observatories of Chinese Academic of Sciences (NAOC).

In this work, the researchers found 1,272 superflares of 311 solar-type stars from the TESS data, and over 7,454 solar-type stars in the TESS catalogue have corresponding LAMOST spectral data, among which 79 stars generated superflares.  

Using the LAMOST spectral data, they estimated the stellar S-index, which is closely related to stellar spots. The value of S-index is positively correlated with stellar magnetic strength.

Meanwhile, TESS not only provides the opportunity to search for superflare events with stellar light curves, but also gives the chance to estimate stellar spots coverage rate (Rvar) of the stars. The Rvar value is directly related to the capability of a star for generating superflares.  

Fig. 2 Distribution of S-index and Rvar of the solar-type stars. (Image by TU Zuolin)   

The researchers found that those flaring stars apparently show relatively higher S-index and Rvar than other none-flaring stars. Furthermore, compared with S-index and Rvar of the Sun, flaring solar-type stars are much more active.  

“Our work confirms that a single solar-type star can generate superflares,” said TU Zuolin, the first author of the study. “We might be safe, because the possibility of the Sun to generate superflares and destroy the Earth is low.”

In the future, the researchers will use more spectroscopic information including medium-resolution surveys from LAMOST to understand the physical mechanism of superflares on solar-type stars, more deeply and comprehensively. 

Featured image: Cartoon image showing the Sun’s superflare, the Earth and Moon (Image by TU Zuolin)   


Superflares, Chromospheric Activities, and Photometric Variabilities of Solar-type Starsfrom the Second-year Observation of TESS and Spectra of LAMOST

Provided by Chinese Academy of Sciences

Scientists Present New Measurements of β-delayed Two-proton Decay of 27S (Physics)

Two-proton decay is a quantum tunnelling process. The tunnelling probability depends on the available energy and the height of the Coulomb barrier, which in turn depends on the nuclear charge Z (number of protons). Two-proton emission is a typical three-body breakup process, including the daughter nucleus and two protons, in which pairing correlations play an important role. Therefore, a detailed study of two-proton emission is of great significance for exploring the open quantum system, pairing correlations and exotic nuclear structure. 

Recently, researchers at the Institute of Modern Physics of the Chinese Academy of Sciences (CAS) and their collaborators carried out measurements for β-delayed two-proton emission (β2p) of the proton drip-line nucleus 27S at the National Laboratory of Heavy Ion Research Facility of Lanzhou (HIRFL). For the first time, they have measured the proton-proton angular correlations of 27S β2p. 

Researchers developed a state-of-the-art detection array for β decay spectroscopy of nuclei far away from the valley of stability. This array consists of three double-sided silicon strip detectors, three quadrant silicon detectors and five Clover-type HPGe detectors at the Radioactive Ion Beam Line in Lanzhou (RIBLL1), which can be used to measure the energies, time and positions of the heavy ions and decay protons.

Distribution of the opening angle of two protons in the decay of 27S. (Image from Physical Review C)

An energy peak at 6372(15) keV with a branching ratio of 2.4(5)% was identified as a two-proton transition via the isobaric-analog state in 27P to the ground state of 25Al in the β decay of 27S. Two-proton angular correlations of 27S β2p were measured by the silicon array for the first time to study the mechanism of two-proton emission. Based on experimental results and Monte Carlo simulations, it was found that the main mechanism for the emission of β2p by 27S is of sequential nature. 

The results were published in Physical Review C on June 15. 

This work is supported by the Strategic Priority Research Program of CAS, the Ministry of Science and Technology of China under National Key R&D Programs, the National Natural Science Foundation of China, and the Continuous Basic Scientific Research Project. 

Featured image: The quantum tunnelling process of two-proton decay. (Image by SUN Lijie)

Reference: G. Z. Shi (石国柱) et al., “β-delayed two-proton decay of 27S at the proton-drip line”, Phys. Rev. C 103, L061301 – Published 15 June 2021. DOI:

Provided by Chinese Academy of Sciences

Roughness of Retinal Layers, A New Alzheimer’s Biomarker (Neuroscience)

Over recent years, the retina has established its position as one of the most promising biomarkers for the early diagnosis of Alzheimer’s. Moving on from the debate as to the retina becoming thinner or thicker, researchers from the Universidad Complutense de Madrid and Hospital Clínico San Carlos are focusing their attention on the roughness of the ten retinal layers.

The study, published in Scientific Reports, “proves innovative” in three aspects according to José Manuel Ramírez, Director of the IIORC (Ramón Castroviejo Institute of Ophthalmologic Research) at the UCM. “This is the first study to propose studying the roughness of the retina and its ten constituent layers. They have devised a mathematical method to measure the degree of wrinkling, through the fractal dimension, and have discovered that in some layers of the retina these measurements indicate that wrinkling begins at very early stages of Alzheimer’s disease,” explains the IIORC expert.

To undertake the study, launched six years ago, the researchers developed computer programs allowing them to separate each layer of the retina. Following this subdivision, the problem which arose was how to distinguish the roughness of one layer from that of the neighbouring layers.

“As each is in contact with the others, the wrinkling of one layer is transmitted to the adjacent layers, and their roughness becomes blurred. The solution was to flatten each layer mathematically on each side and study the roughness remaining on the other side,” indicates Lucía Jáñez, the lead author of the publication.

Software development to calculate roughness

The second problem faced in the research was to find a procedure to measure roughness. “The solution lay in calculating the fractal dimension of the side of each retinal layer studied,” explains Luis Jáñez, researcher at the UCM’s ITC (Institute of Knowledge Technology).

“A flat surface has only two dimensions: length and width, but if it is folded or wrinkled it progressively takes on body and begins to appear a three-dimensional solid object. The fractal dimension adopts fractional values between 2 and 3, and so is suitable to measure the degree of wrinkling of retinal layers,” he adds.

The final step taken by the group was to incorporate the technology they had developed within the Optical Coherence Tomography (OCT) currently available on the market, using mathematical analysis to express this in software which calculates the roughness of each retinal layer, and establishes the boundary between health/illness.

For the patient, this is a simple, quick and low-cost test. “No prior preparation is required. They simply turn up for an ophthalmology appointment, sit facing the machine and spend about 4 seconds looking at a dot of light inside: that generates the OCT image. The analysis of the roughness of the image is performed by a computer program in less than one minute,” the ITC researcher indicates.

After a decade working in this field, researchers understand how the eyesight of patients with Alzheimer’s evolves, and the changes in retinal thickness. “From now on, with this new technique we can research how to use retinal roughness to monitor and ascertain the stage of Alzheimer’s disease,” predicts the IIORC researcher Elena Salobrar García.

As well as being used in Alzheimer’s, the methods they have developed could be applied in studying other diseases, such as ALS or Parkinson’s, “the effects of which on the retina we are now beginning to understand. As well as contributing to advances in neuroscience, this might also be useful in ophthalmology,” concludes Omar Bachtoula, researcher at the UCM Psychology Faculty.

Reference: Jáñez-García, L., Bachtoula, O., Salobrar-García, E. et al. Roughness of retinal layers in Alzheimer’s disease. Sci Rep 11, 11804 (2021).

Provided by UCM

Study Reveals Formation Mechanism of First Carbon-carbon Bond in MTO Process (Chemistry)

A joint research team led by Prof. LIU Zhongmin, Prof. WEI Yingxu, and Prof. XU Shutao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) revealed the mechanism underlying the formation of the first carbon-carbon (C-C) bond formation during the methanol-to-olefins (MTO) process.

This study was published in Chem on June 23.

Prof. ZHENG Anmin’s group from Innovation Academy for Precision Measurement Science and Technology of CAS was also involved in the study.

The first C-C bond in the MTO process is formed at the initial stage of the reaction. There is no direct method to elucidate the bond formation /reaction mechanism due to the difficulty in capturing intermediate species.

“We investigated the direct C-C bond formation mechanism during the initial MTO reaction over HSSZ-13 zeolite with an 8-membered ring and a chabazite topological structure,” said Prof. XU.

They detected the evolution of the organic species on the SSZ-13 catalyst surface during the methanol conversion. For the first time, they directly captured the surface ethoxy species (SES), the critical species containing the initial C-C bond under real MTO reaction conditions at the initial reaction stage.

Moreover, the researchers employed the ab initio molecular dynamics (AIMD) theoretical calculation simulation to predict and present the visualized and complete process of initial C-C bond formation starting from the C1 reactants and C1 intermediates.

Based on the experimental and theoretical evidence, they established the complete and feasible initial C-C bond formation routes, namely, surface methoxy species (SMS)/trimethoxyonium (TMO) mediated methanol/dimethyl ether (DME) activation with a synergistic effect from SMS and the negatively charged framework oxygen atoms to form SES.

“Our study not only sheds light on the controversial issue of the first C-C bond formation in the MTO process, but also enriches the fundamental theory of C1 catalytic chemistry,” said Prof. WEI.

This work was supported by the National Natural Science Foundation of China, Strategic Priority Research Program of the Chinese Academy of Sciences, iChEM, the Youth Innovation Promotion Association of the Chinese Academy of Sciences and Liaoning Revitalization Talents Program.

Featured image: Revealing the whole first C-C bond formation processes in MTO reaction: based on the in situ NMR spectroscopic evidences and advanced ab initio molecular dynamics (AIMD) theoretical calculation method © DICP

Reference: Shutao Xu, Yuchun Zhi, Jingfeng Han, Wenna Zhang, Xinqiang Wu, Tantan Sun, Yingxu Wei, Zhongmin Liu, Chapter Two – Advances in Catalysis for Methanol-to-Olefins Conversion, Editor(s): Chunshan Song, Advances in Catalysis, Academic Press, Volume 61, 2017, Pages 37-122, ISSN 0360-0564, ISBN 9780128120781, (

Provided by DICP

Low-cost Imaging Technique Shows How Smartphone Batteries Could Charge in Minutes (Chemistry)

Researchers have developed a simple lab-based technique that allows them to look inside lithium-ion batteries and follow lithium ions moving in real time as the batteries charge and discharge, something which has not been possible until now.

Using the low-cost technique, the researchers identified the speed-limiting processes which, if addressed, could enable the batteries in most smartphones and laptops to charge in as little as five minutes.

The researchers, from the University of Cambridge, say their technique will not only help improve existing battery materials, but could accelerate the development of next-generation batteries, one of the biggest technological hurdles to be overcome in the transition to a fossil fuel-free world. The results are reported in the journal Nature.

While lithium-ion batteries have undeniable advantages, such as relatively high energy densities and long lifetimes in comparison with other batteries and means of energy storage, they can also overheat or even explode, and are relatively expensive to produce. Additionally, their energy density is nowhere near that of petrol. So far, this makes them unsuitable for widespread use in two major clean technologies: electric cars and grid-scale storage for solar power.

“A better battery is one that can store a lot more energy or one that can charge much faster – ideally both,” said co-author Dr Christoph Schnedermann, from Cambridge’s Cavendish Laboratory. “But to make better batteries out of new materials, and to improve the batteries we’re already using, we need to understand what’s going on inside them.”

To improve lithium-ion batteries and help them charge faster, researchers need to follow and understand the processes occurring in functioning materials under realistic conditions in real time. Currently, this requires sophisticated synchrotron X-ray or electron microscopy techniques, which are time-consuming and expensive.

“To really study what’s happening inside a battery, you essentially have to get the microscope to do two things at once: it needs to observe batteries charging and discharging over a period of several hours, but at the same time it needs to capture very fast processes happening inside the battery,” said first author Alice Merryweather, a PhD student at Cambridge’s Cavendish Laboratory.

The Cambridge team developed an optical microscopy technique called interferometric scattering microscopy to observe these processes at work. Using this technique, they were able to observe individual particles of lithium cobalt oxide (often referred to as LCO) charging and discharging by measuring the amount of scattered light.

They were able to see the LCO going through a series of phase transitions in the charge-discharge cycle. The phase boundaries within the LCO particles move and change as lithium ions go in and out. The researchers found that the mechanism of the moving boundary is different depending on whether the battery is charging or discharging.

“We found that there are different speed limits for lithium-ion batteries, depending on whether it’s charging or discharging,” said Dr Akshay Rao from the Cavendish Laboratory, who led the research. “When charging, the speed depends on how fast the lithium ions can pass through the particles of active material. When discharging, the speed depends on how fast the ions are inserted at the edges. If we can control these two mechanisms, it would enable lithium-ion batteries to charge much faster.”

“Given that lithium-ion batteries have been in use for decades, you’d think we know everything there is to know about them, but that’s not the case,” said Schnedermann. “This technique lets us see just how fast it might be able to go through a charge-discharge cycle. What we’re really looking forward to is using the technique to study next-generation battery materials – we can use what we learned about LCO to develop new materials.”

“The technique is a quite general way of looking at ion dynamics in solid state materials, so you can use it on almost any type of battery material,” said Professor Clare Grey, from Cambridge’s Yusuf Hamied Department of Chemistry, who co-led the research.

The high throughput nature of the methodology allows many particles to be sampled across the entire electrode and, moving forward, will enable further exploration of what happens when batteries fail and how to prevent it.

“This lab-based technique we’ve developed offers a huge change in technology speed so that we can keep up with the fast-moving inner workings of a battery,” said Schnedermann. “The fact that we can actually see these phase boundaries changing in real time was really surprising. This technique could be an important piece of the puzzle in the development of next-generation batteries.”

Reference: Merryweather, A.J., Schnedermann, C., Jacquet, Q. et al. Operando optical tracking of single-particle ion dynamics in batteries. Nature 594, 522–528 (2021).

Provided by University of Cambridge

Pleistocene Sediment DNA from Denisova Cave (Paleontology)

Sediment DNA tracks 300,000 years of hominin and animal presence at Denisova Cave

Denisova Cave is located in the Altai Mountains in southern Siberia and is famous for the discovery of Denisovans, an extinct form of archaic humans that is thought to have occupied large parts of central and eastern Asia. Neandertal remains have also been found at the site, as well as a bone from a child who had a Neandertal mother and Denisovan father, showing that both groups met in the region. However, only eight bone fragments and teeth of Neandertals and Denisovans have been recovered so far from the deposits in Denisova Cave, which cover a time span of over 300,000 years. These are too few fossils to reconstruct the occupational history of the site in detail, or to link the different types of stone tools and other artefacts found in Denisova Cave to specific hominin groups. For example, the discovery of jewelry and pendants typical of the so-called Initial Upper Palaeolithic culture in approximately 45,000-year-old layers has prompted debates as to whether Denisovans, Neandertals or modern humans were the creators of these artefacts.

Michael Shunkov of the Siberian Branch of the Russian Academy of Sciences, who leads the excavations at Denisova Cave, assembled an interdisciplinary team of archaeologists, geneticists, geochronologists and other scientists to study this unique site. The team has now performed the largest analysis ever of sediment DNA from a single excavation site. “The analysis of sediment DNA provides a wonderful opportunity to combine the dates that we previously determined for the deposits in Denisova Cave with molecular evidence for the presence of people and fauna”, says Richard ‘Bert’ Roberts from the University of Wollongong in Australia. The team of geochronologists led by him and Zenobia Jacobs collected more than 700 sediment samples in a dense grid from the exposed sediment profiles in the cave. “Just collecting the samples from all three chambers in the cave, and documenting their precise locations, took us more than a week”, Jacobs says.

Traces of DNA in the sediment

Researchers Zenobia Jacobs, Bo Li and Kieran O’Gorman collecting sediment samples in the Main Chamber. © Richard G. Roberts

When the samples arrived at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Elena Zavala, the lead author of the study, spent another two years in the lab to extract and sequence small traces of ancient hominin and animal mitochondrial DNA from this huge collection of samples. “These efforts paid off and we detected the DNA of Denisovans, Neandertals or ancient modern humans in 175 of the samples”, Zavala says.

When matching the DNA profiles with the ages of the layers, the researchers found that the earliest hominin DNA belonged to Denisovans, indicating that they produced the oldest stone tools at the site between 250,000 and 170,000 years ago. The first Neandertals arrived towards the end of this time period, after which both Denisovans and Neandertals frequented the site – except between 130,000 and 100,000 years ago, when no Denisovan DNA was detected in the sediments. The Denisovans who came back after this time carried a different mitochondrial DNA, suggesting that a different population arrived in the region.

New tools

Researchers Zenobia Jacobs, Bo Li and Kieran O’Gorman collecting sediment samples in the South Chamber. © Credit: Dr. Richard G. Roberts

Modern human mitochondrial DNA first appears in the layers containing Initial Upper Palaeolithic tools and other objects, which are much more diverse than in the older layers. “This provides not only the first evidence of ancient modern humans at the site, but also suggests that they may have brought new technology into the region with them”, says Zavala.

The scientists studied animal DNA and identified two time periods where changes occurred in both animal and hominin populations. The first, around 190,000 years ago, coincided with a shift from relatively warm (interglacial) conditions to a relatively cold (glacial) climate, when hyaena and bear populations changed and Neandertals first appeared in the cave. The second major change occurred between 130,000 and 100,000 years ago, along with a shift in climate from relatively cold to relatively warm conditions. During this period, Denisovans were absent and animal populations changed again.

“I believe that our Russian colleagues who excavate this amazing site have set the standards for many future archaeological excavations with their careful collection of many samples from each archaeological layer for DNA analysis”, says Svante Pääbo who initiated the study with the Russian team. “Being able to generate such dense genetic data from an archaeological site is like a dream come true, and these are just the beginnings”, says Matthias Meyer, the senior author on the study. “There is so much information hidden in sediments – it will keep us and many other geneticists busy for a lifetime.”

Featured image: The entrance to Denisova Cave, the famous site in southern Siberia where remains of both Neandertals and their Asian relatives, the Denisovans, have been found. © Richard G. Roberts

Reference: Elena Zavala et al.Pleistocene sediment DNA reveals hominin and faunal turnovers at Denisova CaveNature, 23 June 2021, DOI: 10.1038/s41586-021-03675-0

Provided by Max Planck Institute for Evolutionary Anthropology

Outstanding Organic Solar Cells’ Performance Achieved By Using New Technology (Chemistry)

Organic solar elements with the self-assembling molecular-thin layer (SAM) of hole-transporting material, the technology, which was used in producing a record-breaking tandem solar cell, achieved 18.4 power conversion efficiency. The invention of Lithuanian chemists working at Kaunas University of Technology (KTU), commercialized by several global companies proved versatile and applicable to different solar technologies.

Organic solar cells are made of common organic elements such as carbon, hydrogen, nitrogen, fluorine, oxygen, and sulphur. Their raw materials are cheap, abundant, and can be easily recycled. Although the organic photovoltaic (OPV) elements are lighter, more flexible and cheaper to produce, their efficiency still falls behind that of other photovoltaic technologies, including silicone, perovskite and tandem solar cells. And yet, this aspect may soon change.

Solar cells developed in Lithuania and Saudi Arabia

At the end of 2018, a group of Lithuanian chemists from Kaunas University of Technology synthesised a material, which self-assembles into a molecule-thick layer, aka monolayer, can cover a variety of surfaces and function as a hole-transporting layer in a solar element. Until recently, the self-assembling monolayers (SAMs) have been used to produce record-breaking perovskite/silicon and CIGS/perovskite tandem solar cells. However, the technology also proved very efficient – reaching nearly record-breaking 18.4 power conversion – when used in an organic solar cell, produced by the group of researchers headed by Professor Thomas Anthopoulos at the KAUST University in Saudi Arabia.

Dr Artiom Magomedov, c0-author of the invention © KTU

“We made some modifications in the material used in SAM formation to tailor it for organic solar elements. However, our technology, offering a breakthrough approach towards photovoltaic elements’ production remains the same: the surface is dipped into a solution and a molecule-thick semiconductor layer is formed. The technology is cheap, efficient and versatile”, says Dr Artiom Magomedov of KTU Faculty of Chemical Technology, the co-author of the invention.

Organic solar cell achieved 18.4 efficiency

As the materials synthesised by KTU chemists are now commercialised and freely available in the market for research groups and companies all over the world, the discovery continues to advance the development of photovoltaic technologies.

“Last year, we noticed an article published by the researchers from KAUST, where they described the achieved very high efficiency of an organic solar cell while using our SAMs. We contacted the scientists and offered to collaborate in enhancing the capacities of the material. Due to the pandemic restrictions, all cooperation was remote – we sent the synthesised materials by post and our colleagues in Saudi Arabia built the organic solar cells and measured their properties”, explains Dr Magomedov.

The organic solar cell using Br-2PACz molecule-thin coating as a hole-transporting layer achieved a power conversion efficiency of 18.4 per cent, which is currently among the highest in OPV technologies. Moreover, the electrode constructed was chemically stable, and after removal of the SAM, it could be recycled and reused to construct fresh highly-performing OPV cells.

All solar technologies will find their niches

The researchers emphasise that the use of similar SAMs could be potentially extended in other applications including light-emitting diodes, photodetectors or organic transistors. According to Dr Magomedov, all different solar technologies, which are currently being developed, will find their niches in the market – as OPV cells are lighter, can be made transparent and flexible, they can be used for charging drones, household electronics, for indoor photovoltaics. Currently, no OPV elements are mass-produced.

Professor Vytautas Getautis © KTU

“The semiconducting properties of organic elements are lower than those of non-organic materials. Therefore, the achieved efficiency results are very impressive for everyone working in the field. After the publication, a Swedish company “Dyenamo” has already obtained the licence to produce our materials tailored for the organic solar elements, as they see the potential of this technology”, says Professor Vytautas Getautis, the Head of the KTU research group behind the invention.

Featured image: Chemists from Kaunas University of Technology synthesised a material, which self-assembles into a molecule-thick layer, aka monolayer, can cover a variety of surfaces and function as a hole-transporting layer in a solar element. © KTU

Reference: Lin, Y., Magomedov, A., Firdaus, Y., Kaltsas, D., El-Labban, A., Faber, H., Naphade, D.R., Yengel, E., Zheng, X., Yarali, E., Chaturvedi, N., Loganathan, K., Gkeka, D., AlShammari, S.H., Bakr, O.M., Laquai, F., Tsetseris, L., Getautis, V. & Anthopoulos, T.D. 18.4% Organic solar cells using a high ionization energy self‐assembled monolayer as hole extraction interlayer, ChemSusChem 2021, 14, 1– 1. Article accessible here.

Provided by KTU