Tech

More and more, people are using internet forums as first place to look for information on health issues. However, the scientific medical information being provided there is often so complex that laypeople are barely able to form considered judgements on the content of much of the advice. One criterion which users apply instead in evaluating the information is the style of the language used. This is the result of the research carried out by psychologists at the University of Münster (Germany). In an online experiment, the test persons placed greater trust in authors in health forums - and also found their recommendations more credible - when the articles were formulated in a neutral style, rather than containing many positive adjectives. The study has been published in the Journal of Medical Internet Research.

Background and method:

In an online experiment, the researchers showed articles in a health forum, formulated in different ways, to 242 test persons. The articles contained an author's assessment, in reply to a woman's enquiry, as to how effective a certain medication was. Depending on the test conditions, the test persons read either a piece of advice containing a large number of positive adjectives such as "outstanding" and "excellent", or a comment formulated in a neutral way. The result was that the test persons rated the author of the article with the positive language as being less trustworthy. They attributed to him not only a lower level of goodwill and integrity, but also more manipulative intentions. The advice offered by the author was also considered to be less credible than that given in the neutrally formulated article.

The author's professional background, on the other hand, had no influence on the assessments given by the users. In the experiment the author described himself in one case as a researcher at a university, in another case as someone representing the interests of the pharmaceutical industry. "This is an interesting result, because in an earlier study we were able to demonstrate that a person's profession can in fact influence the trustworthiness and credibility of their arguments," explains Dr. Lars König, who carried out the study as part of his PhD thesis at the Research Training Group "Trust and Communication in a Digitized World" under Prof. Regina Jucks. "More research would need to be done for a better understanding of the conditions under which the author's profession is, in fact, important for readers," he adds.

Over the past few years, many authors of scientific articles or of posts in health forums have started using a positive style of language in order to underline the relevance of their research or advice and, not least, to influence readers. As internet forums are not subject to any controls, they include not only scientific or medical information but also, frequently, imprecise or wrong advice. Because of the complex nature of the health issues at stake, laypeople are unable to evaluate this false information and so they have to be guided by other characteristics of the recommendations.

The findings from the experiment are especially relevant for doctors who are increasingly contacting their patients through digital communication media. Also researchers can benefit from the findings as they try increasingly to present their latest research results and conclusions in an easy-to-understand way for the general public.

"As there are indications that any evaluation of experts' comments also depends on the issue in question, as well as on the gender of the author and of the reader, future research should focus especially on these points," says Lars König. In future experiments, he says, the gender of the author could be varied, for example, in order to examine what impact this has on the style of language and on how the person giving the information is rated.

The growing threat of drought and rising water demand have made accurate forecasts of crop water use critical for farmland water management and sustainability.

But limitations in existing models and satellite data pose challenges for precise estimates of evapotranspiration -- a combination of evaporation from soil and transpiration from plants. The process is complex and difficult to model, and existing remote-sensing data can't provide accurate, high-resolution information on a daily basis.

A new high-resolution mapping framework called BESS-STAIR promises to do just that, around the globe. BESS-STAIR is composed of a satellite-driven biophysical model integrating plants' water, carbon and energy cycles -- the Breathing Earth System Simulator (BESS) -- with a generic and fully automated fusion algorithm called STAIR (SaTellite dAta IntegRation).

The framework, developed by researchers with the U.S. Department of Energy's Center for Advanced Bioenergy and Bioproducts Innovation (CABBI) at the University of Illinois at Urbana-Champaign, was tested in 12 sites across the U.S. Corn Belt, and its estimates have achieved the highest performance reported in any academic study so far.

The study, published in Hydrology and Earth System Sciences, was led by Postdoctoral Research Associate Chongya Jiang, from CABBI's sustainability theme, and project lead Kaiyu Guan, Assistant Professor in the Department of Natural Resources and Environmental Sciences (NRES) and a Blue Waters Professor at the National Center for Supercomputing Applications (NCSA).

"BESS-STAIR has great potential to be a reliable tool for water resources management and precision agriculture applications for the U.S. Corn Belt and even worldwide, given the global coverage of its input data," Jiang said.

Traditional remote-sensing methods for estimating evapotranspiration rely heavily on thermal radiation data, measuring the temperature of the plant canopy and soil as they cool through evaporation. But those methods have two drawbacks: the satellites can't collect data on surface temperatures on cloudy days; and the temperature data aren't very accurate, which in turn affects the accuracy of the evapotranspiration estimates, Jiang said.

The CABBI team instead focused on the plant's carbon-water-energy cycles. Plants transpire water into the atmosphere through holes on their leaves called stomata. As the water goes out, carbon dioxide comes in, allowing the plant to conduct photosynthesis and form biomass.

The BESS-STAIR model first estimates photosynthesis, then the amount of carbon and water going in and out. Previous remote-sensing methods did not consider the carbon component as a constraint, Jiang said. "That's the advance of this model."

Another advantage: Surface temperature-based methods can only collect data under clear skies, so they have to interpolate evapotranspiration for cloudy days, creating gaps in the data, he said. The all-weather BESS-STAIR model uses surface reflectance, which is similar on clear and cloudy days, eliminating any gaps.

The STAIR algorithm fused data from two complementary satellite systems -- Landsat and MODIS -- to provide high-resolution data on a daily basis, providing both high spatial and high temporal resolution. Landsat collects detailed information about Earth's land every eight to 16 days; MODIS provides a complete picture of the globe every day to capture more rapid land surface changes.

This isn't the first time researchers have combined data from the two satellite sensors, but previous methods only worked in a small region over a short time period, Guan said. The previous algorithms were difficult to scale up and weren't fully automatic, requiring significant human input, and they couldn't be applied across broad areas over a longer time period.

By contrast, the CABBI team's framework was evaluated in different regions across the U.S. Corn Belt over two decades, Jiang said. Researchers built a pipeline on NCSA's supercomputer to automatically estimate surface reflectance as well as evapotranspiration on a large scale for extended time periods. Using data from 2000 to 2017, the team applied BESS-STAIR in 12 sites across the Corn Belt, comprehensively validating its evapotranspiration estimates with flux tower measurements at each site. They measured overall accuracy as well as and spatial, seasonal, and interannual variations.

"We are able to provide daily, 30m-resolution evapotranspiration anytime and anywhere in the U.S. Corn Belt in hours, which is unprecedented," Guan said.

The breakthrough will have real-time, practical benefits for U.S. farmers coping with the increasing severity of droughts, as documented in a number of recent studies.

"Precision agriculture is one of our major targets. Evapotranspiration is very important for irrigation and also very important to water management," Guan said. "This is a solution that goes beyond experimental plots and impacts the real world, for millions of fields everywhere."

Below please find links to new coronavirus-related content published today in Annals of Internal Medicine. All coronavirus-related content published in Annals of Internal Medicine is free to the public. A complete collection is available at https://annals.org/aim/pages/coronavirus-content.

Also new in this issue:

Knowledge and perceptions of coronavirus disease 2019 among the general public in the United States and the United Kingdom: A cross-sectional online survey

Pascal Geldsetzer MD PhD MPH

Brief Research Report

Abstract: http://annals.org/aim/article/doi/10.7326/M20-0912

Media contact: To speak with lead author, Pascal Geldsetzer MD PhD MPH, please contact Tracie White at traciew@stanford.edu.

Oncotarget Volume 11, Issue 11 reported that in order to understand the molecular mechanism of the dependency in MM, the research team examined gene expression changes upon DOT1L inhibition in sensitive and insensitive cell lines and discovered that genes belonging to the endoplasmic reticulum stress pathway and protein synthesis machinery were specifically suppressed in sensitive cells.

Whole-genome CRISPR screens in the presence or absence of a DOT1L inhibitor revealed that concomitant targeting of the H3K4me3 methyltransferase SETD1B increases the effect of DOT1L inhibition.

Dr. Ralph Tiedt from Novartis Institutes for BioMedical Research (NIBR) Oncology, Basel, Switzerland said, "MM is an aggressive hematologic cancer characterized by the monoclonal expansion of plasma cells secreting high amounts of immunoglobulins."

"MM is an aggressive hematologic cancer characterized by the monoclonal expansion of plasma cells secreting high amounts of immunoglobulins."

- Dr. Ralph Tiedt, Novartis Institutes for BioMedical Research (NIBR) Oncology

The sensitivity of MM cells to proteasome inhibitors is thought to be due to perturbation of the hyperactive UPR, which may offer some degree of selectivity versus non-cancerous cells.

Through pharmacologic and genetic approaches, we found that inhibition of DOT1L, an H3K79 methyltransferase, profoundly reduces the viability of a subset of MM cell lines in vitro and inhibits the growth of established MM xenografts in mice.

CRISPR screens further revealed that targeting the histone methyltransferase SETD1B concomitantly with DOT1L further enhances this effect on the UPR and increases and accelerates MM cell death.

The Tiedt Research Team concluded in their Oncotarget Research Paper, "our discovery indicates a novel opportunity for DOT1L inhibitors in cancer treatment. Concomitant targeting of SETD1B enhances phenotypic and transcriptional effects of DOT1L inhibition in sensitive MM cell lines, which may be an additional therapeutic angle. To our knowledge, no selective SETD1B inhibitors have been described yet, and our data questions whether its methyltransferase activity is critical in the MM context. Additional work is needed to address this question and guide drug discovery."

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DOI - https://doi.org/10.18632/oncotarget.27493

Full text - http://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path[]=27493&path[]=90094

Correspondence to - Ralph Tiedt - ralph.tiedt@novartis.com

Journal

Oncotarget

DOI

10.18632/oncotarget.27493

Today, when new drugs are designed with the help of supercomputers, and electronic devices operate on a nanoscale, it is very important for scientists to understand how neighboring molecules behave towards each other. For this purpose, they need to know the sizes of atoms with the highest degree of precision. Modern quantum chemistry methods can be of help here, but the answers they offer are either not accurate enough or take months of work to produce. Scientists from ITMO University and their colleagues from the Russian Academy of Science proposed a new method of statistical analysis of intermolecular interactions and sizes of atoms. Their research made the front page of the ChemPhysChem journal.

From the chemistry standpoint, we all live in a world of perpetual intermolecular interactions. The process of brewing tea, digesting our meals or the rigidity of a new type of plastic - all of this depends on the manner of interaction of specific molecules. The problem is that modern quantum chemistry methods aren't enough to completely and precisely describe the characteristics of intermolecular interactions.

Then again, today it is very important for scientists to know the energy of intermolecular interactions. Researchers need precise data on how molecules of a new drug interact with an organism's cells, or on the molecular structure of a new semiconductor. The smallest changes in the manner of molecules' interaction can make an invention very effective or completely unfeasible. Chemists found a way out: in order to identify the extent to which intermolecular interactions affect the properties of a chemical system, they started using the principle of the effective size of atoms, most commonly known as van der Waals radii. This concept implies that if atoms get closer to each other than a specific distance, then their interaction is significant; otherwise, it can be neglected.

Yet, due to the specifics of the method for determining van der Waals radii, their values are usually undersized by 10-15%. As a result, mistakes make their way into the analysis of chemical systems, and many interactions are neglected as insignificant. A team of scientists from ITMO University in collaboration with specialists from Nesmeyanov Institute of Organoelement Compounds proposed a new method of statistical analysis that allows to determine the size of atoms better.

"How do you usually calculate the efficient size of atoms? says Ivan Chernyshov, one of the article's authors, - well, we have data on all possible interactions between two atoms. If we draw up a graph of the distribution of interatomic distances, we'll be able to get an average distance that corresponds to the analyzed interaction. Still, this is not always possible, so instead of the most probable distance from the graph we get a different, approximate value. We succeeded in getting round this problem by coming up with a way to sift the accidental contacts from direct interactions where there are no other screening atoms on the "line of sight" between the centers of the two atoms."

Despite this method for solving an extremely complex task from the field of quantum chemistry being quite simple, it allows to get sufficiently precise data that is essential for assessing the sizes of atoms and molecules and the manner of intermolecular interactions, which is very important in the light of today's applications.

"Today, scientists actively research interactions between drugs and proteins in organisms, explains Mr. Chernyshov. You have a good molecule that has already shown its efficiency, but need to improve it by amplifying the bond with the active center. In order to do that, you take data on the efficient size of these atoms and see which interactions in the structure of the bound protein are important and which can be neglected. The values that have been used till now were determined empirically and had no specific physical sense. Our method will make it possible to significantly increase the precision of such calculations, especially for systems that have not been studied yet."

Electrocatalysis is one of the most studied topics in the field of material science, because it is extensively involved in many important energy-related processes, such as the oxygen reduction reaction (ORR) for fuel cells, the hydrogen evolution reaction (HER) for green hydrogen production, and the oxygen evolution reaction (OER) for metal-air batteries. Noble metal aerogels (NMAs) emerge as a new class of outstanding electrocatalysts due to the combined features of metals and aerogels. However, the development of these porous materials has yet been impeded by the sluggish fabrication methods, which require several hours to even several weeks. In addition, the unique optical properties of noble metals, for instance the plasmonic resonance, have so far been ignored in NMAs, limiting their potential high performance in electrocatalysis.

Ran Du from China is an Alexander von Humboldt research fellow working as postdoc in the physical chemistry group of Professor Alexander Eychmüller at TU Dresden since 2017. Together, they recently revealed an unconventional self-healing behaviour in noble metal gels, which is rare in the solely inorganic gel systems. On this basis, a counter-intuition method was developed for tremendously accelerating the gelation speed. Their pioneering findings were published in the renowned journal Matter.

Ran Du and his team developed an unconventional and conceptually new strategy for rapid gelation: a counter-intuitive disturbance-promoted gelation method. The in situ introduction of a disturbing field during the gelation greatly facilitates mass transportation and induces accelerated reaction kinetics. Upon removal of the disturbing field, the resulting gel pieces can re-assemble to a monolith in light of the self-healing property. In this way, the transportation barrier in presence of traditional gelation methods is overcome, leading to a gelation within one to ten minutes at room temperature without affecting the microstructures of gels. This is two to three orders of the magnitude quicker than traditional approaches. The mechanism was also supported by Monte Carlo simulations. Notably, the disturbance ways can be expanded to shaking and bubbling, and the method is applicable to various compositions, such as gold (Au), palladium (Pd), rhodium (Rh), gold-palladium (Au-Pd), gold-palladium-platinum (Au-Pd-Pt), and morphologies, for example the core-shell structure or homogeneous structure.

Moreover, Ran Du took advantage of the combined optic and catalytic activities of noble metals: "We also were first to demonstrate the photoelectrocatalytic properties of NMAs by using ethanol oxidation reaction (EOR) as a model reaction, displaying an activity increase of up to 45.5 % by illumination and realizing a current density of up to 7.3 times higher than that of commercial palladium/carbon (Pd/C). Thus we pioneered the exploration of photoelectrocatalysis on NMAs opening up new space for both fundamental and application-orientated studies for noble metal gels and other systems."

Though biodiversity is in crisis globally, amphibians in particular face a variety of threats. One such threat comes from pathogens like the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). This fungus causes chytridiomycosis, a disease that research indicates contributes to the decline of some amphibians. New research, however, now calls into question some prior evidence that links the widespread pathogen to hundreds of amphibian declines.

Last year in the journal Science, a research review concluded that the chytrid fungus caused the decline of at least 501 amphibian species, of which 90 have gone extinct. That paper suggested that species losses due to the chytrid fungus are "orders of magnitude greater than for other high-profile wildlife pathogens." But a recent reanalysis led by University of California, Berkeley, researchers found that the paper's main conclusions lack evidence and are unreproducible.

In a Comment published online March 19th in Science, the group conducting the reanalysis -- including lead authors Max Lambert and Molly Womack, who are postdocs in the lab of professor Erica Rosenblum in the Department of Environmental Science, Policy, and Management (ESPM) at UC Berkeley -- identified a number of data deficiencies and methodological issues in the Scheele study. Working through the methods and datasets, they faced challenges in reproducing conclusions while identifying numerous instances of missing data. In some cases, data gaps failed to link the fungus to species declines -- even for many species which were previously reported with high certainty that the fungus was the cause.

Lambert and Womack note that their reanalysis does not minimize the role the chytrid fungus has played in amphibian declines and that "chytridiomycosis has irrefutably harmed amphibians."

A number of co-authors involved in the reanalysis had previously studied the harmful effects of the chytrid fungus on amphibians in California and Central America. For some species, the data make clear that amphibian chytrid fungus, which has received tremendous attention, has contributed to declines. However, Lambert, Womack, and their collaborators found that the evidence in Scheele et al.'s analysis is negligible -- or even absent -- for many important species.

They state that it remains unclear exactly how many and which amphibian species have been harmed by the fungus. Relative to other threats that amphibians face, the role chytrid plays in global declines is also uncertain. In many cases, according to the Science comment, the cause of amphibian declines remains a mystery.

The reanalysis authors argue that transparent data collection and analysis are crucial -- both for science and conservation efforts. "It is more critical than ever for scientists to provide responsible narratives based on transparent and reproducible data and methods," says Lambert. "Doing so will produce better science and more effective conservation."

In a new publication from Cardiovascular Innovations and Applications; DOI https://doi.org/10.15212/CVIA.2019.0570, Fabian Guenther, Andreas Seitz, Valeria Martínez Pereyra, Raffi Bekeredjian, Udo Sechtem and Peter Ong from the Department of Cardiology, Robert-Bosch-Krankenhaus, Stuttgart, Germany consider whether coronary microvascular spasm exists.

Real-time coronary blood flow velocity measurement during acetylcholine spasm provocation testing using a Doppler-sensor-equipped wire may facilitate the diagnosis of coronary microvascular spasm, especially if other criteria are ambiguous as emphasized in European Society of Cardiology guidelines for chronic coronary syndromes.

Oncotarget Volume 11, Issue 11 reported that in this preclinical study, we characterized the binding affinity and selectivity of quizartinib, a small-molecule inhibitor of FLT3, and AC886, the active metabolite of quizartinib, compared with those of other FLT3 inhibitors.

Dr. Takeshi Isoyama from Daiichi Sankyo Co., Ltd. said, "FMS like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase expressed by acute myeloid leukemia (AML) cells in 70% to 90% of patients."

"FMS like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase expressed by acute myeloid leukemia (AML) cells in 70% to 90% of patients."

- Dr. Takeshi Isoyama, Daiichi Sankyo Co., Ltd

FLT3 mutations have been found in approximately 30% of AML cases, with internal tandem duplication, commonly found in the juxtamembrane domain of FLT3, occurring in approximately 25% of cases and mutations in the tyrosine kinase domain present in approximately 5%.

Generally, type II inhibitors are more selective than type I inhibitors, as the inactive conformation preferred by type II inhibitors is thought to be more kinase-specific than the active conformation.

Secondary kinase mutations can emerge in FLT3-ITD AML, resulting in resistance to FLT3 inhibitors, and point mutations that confer resistance to a certain FLT3 inhibitor tend to have cross-resistance to other drugs in the same class.

Limited data exist on the efficacy of available FLT3 inhibitors in patients with AML that was relapsed or refractory to first-line midostaurin-based therapy, and strategies to overcome resistance mutations, such as a combination of inhibitors or use of more potent FLT3 inhibitors, are being evaluated.

The objectives of this preclinical study were to characterize the kinase binding affinity and selectivity of quizartinib and its active metabolite AC886 compared with those of other FLT3 inhibitors, to evaluate the antitumor effect of quizartinib on midostaurin-resistant AML cells, and to assess the impact of midostaurin resistance on FLT3 inhibitors.

The Isoyama Research Team concluded in their Oncotarget Research Paper, "we have demonstrated the high affinity and selectivity that quizartinib and its active metabolite AC886 have for FLT3 and that quizartinib maintains preclinical antitumor activity against midostaurin-resistant tumor models. Additional clinical trials will be needed to clarify and optimize the role of quizartinib in the treatment of patients with relapsed or refractory AML who have previously been treated with midostaurin."

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DOI - https://doi.org/10.18632/oncotarget.27489

Full text - http://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path[]=27489&path[]=90090

Correspondence to - Takeshi Isoyama - isoyama.takeshi.y5@daiichisankyo.co.jp

Journal

Oncotarget

DOI

10.18632/oncotarget.27489

Livestock production and nitrogen fertilizer used in croplands emit lots of ammonia, which is the most abundant alkaline gas in ambient air. In recent years, Chinese scientists have suggested reducing ammonia emissions as an effective measure to alleviate aerosol pollution because ammonia can react with acidic gases to form aerosols and pollution.

"Ammonia is also reactive and sticky, and can be removed from the atmosphere quickly. We call this process dry deposition," explains Dr Jianlin Shen, from the Institute of Subtropical Agriculture, Chinese Academy of Sciences. "Agricultural sources contribute to most of the ammonia emissions, but whether all the ammonia emitted from agriculture enters the atmosphere needs to be urgently evaluated." This was the motivation behind a study conducted by Dr Shen and colleagues, recently published study in Atmospheric and Oceanic Science Letters.

The ammonia emissions intensity is relatively high in the subtropical hilly regions of China. The pattern of distribution of croplands or animal farms accompanying the surrounding natural ecosystems in this region may result in a large proportion of the emitted ammonia being deposited in the neighborhood of the sources before entering the atmosphere. Thus, it is important to determine the fate of the emitted ammonia in these subtropical hilly regions of China.

"Paddy fields constitute a major type of cropland in the subtropical hilly regions of China. We developed a method to measure the ammonia dry deposition around ammonia emission sources, and used it to measure the ammonia concentrations and dry deposition within 100 m around paddy fields (0.6 ha) with double rice cropping in the subtropical hilly area of southern China," says Dr Shen.

Based on this study, it was found that there were high ammonia concentrations at downwind sites within 100 m from the paddy fields, which occurred during the 15 days after nitrogen fertilizer application. With an increase in distance from the paddy fields, the atmospheric ammonia concentration at the downwind sites decreased exponentially. Ammonia deposition within 100 m downwind of the paddy fields accounted for about 80% of the ammonia emitted from the paddy fields, and thus only about 20% of the emitted ammonia entered into the atmosphere to form aerosols.

"Our study indicates that ammonia deposition in the neighborhood of sources can largely reduce the amount of emitted ammonia entering the atmosphere, and thus can reduce atmospheric ammonia pollution. This mechanism should be considered in inventory compilations in order to objectively assess the potential impact of agricultural ammonia emissions on air pollution. Measures to increase the level of ammonia deposition around sources, such as by planting trees, are advocated to reduce the amount of ammonia pollution," concludes Dr Shen.

"This study is only a case study. In the future, we intend to study the dry deposition of ammonia around sources with different emission intensities to assess the fate of ammonia when it is emitted from these sources," adds Shen.

Previously, KFU scientists were able to develop the first inhibitors based on castor oil and chitosan. Researchers came up with the idea to create them to solve at least two tasks: ensure efficient production and transportation of hydrocarbons, as well as reduce environmental risks. Now a series of inhibitors has appeared with new reagents based on water-soluble polyurethanes.

"We are looking for new ways to obtain complex reagents - so that one molecule can solve two problems simultaneously. New reagents, as well as those developed by us earlier, effectively inhibit corrosion and hydrate formation. We developed them using urethane technology. This synthesis was carried out in an aqueous medium, which allowed us to obtain water-soluble polyurethanes that can be utilized quite easily," explains Mikhail Varfolomeev, Head of EcoOil Research Unit at the University.

"This reagent has shown high efficiency in the inhibition of hydrates, both in dynamic conditions of pipeline transport and in static conditions. In addition, detailed studies of the new reagent for corrosion inhibition were carried out, and methods of microscopy and electrochemical analysis were used. All of them showed that this reagent forms a protective layer on the metal surface, which prevents corrosion," elaborates co-author Abdolreza Farhadian, Research Associate of the Rheological and Thermochemical Research Lab.

Corrosion and the formation of gas hydrate plugs in offshore oil and gas pipelines pose vital risks to operation and safety. As oil and gas exploration and production moves to deeper deposits and longer pipelines, the costs associated with hydrate blocking will increase significantly.

"The idea is that with the help of our inhibitor you can change the situation with the use of reagents. So far, it is customary to use different inhibitors to eliminate problems with corrosion and gas hydrate plugs, and inhibitors can significantly impair each other's effectiveness. Unlike existing inhibitors, our reagent, in the form of only one molecule, is able to perform these functions. This can qualitatively change the general strategies for applying and solving these problems," adds another co-author Arman Kudbanov.

In their study, by investigating the vibrations of the molecules in the thin films, the scientists were able to show that very fundamental quantum effects, so-called zero point vibrations, can make a significant contribution to voltage losses. The study has now been published in the journal Nature Communications.

Solar cells are a crystallization point of high hopes for the necessary transformation of the global energy production. Organic photovoltaics (OPV), which is based on organic, i.e. carbon-based materials, could be ideally suited to become an important pillar in the energy mix of the "renewables" because they have a better ecological balance sheet compared to conventional silicon-based modules and only a small amount of material is required to produce the thin films. However, a further increase in efficiency is necessary. It is based on various characteristic values such as the open-circuit voltage, whose too low values are currently a main reason for still quite moderate efficiencies of OPV.

The study investigated physical reasons for this - including the vibrations of the molecules in the thin films. It was shown that the so-called zero point vibrations - an effect of quantum physics that characterizes the motion at absolute temperature zero - can have a significant influence on voltage losses. A direct relationship between molecular properties and macroscopic device properties was demonstrated. The results provide important information for the further development and improvement of novel organic materials.

The low energy edge of optical absorption spectra is crucial for the performance of solar cells, but in the case of organic solar cells with many influencing factors it is not yet well understood. In the present study, the microscopic origin of absorption bands in molecular blend systems and their role in organic solar cells was investigated. The focus was on the temperature dependence of the absorption characteristics, which was investigated theoretically under consideration of molecular vibrations. The simulations matched very well with the experimentally measured absorption spectra which leads to a number of important findings.

The authors discovered that the zero-point vibrations, mediated by electron-phonon interaction, cause a considerable absorption bandwidth. This leads to reemission of a part of the energy which is unused and hence reduces the open-circuit voltage. These voltage losses can now be predicted from electronic and vibronic molecular parameters. What is unusual is that this effect is strong even at room temperature and can significantly reduce the efficiency of the organic solar cell. Which strategies to reduce these vibration-induced voltage losses could be applied is being discussed by the authors for a larger number of systems and different heterojunction geometries.

A team of DESY scientists has built a miniature double particle accelerator that can recycle some of the laser energy fed into the system to boost the energy of the accelerated electrons a second time. The device uses narrowband terahertz radiation which lies between infrared and radio frequencies in the electromagnetic spectrum, and a single accelerating tube is just 1.5 centimetres long and 0.79 millimetres in diameter. Dongfang Zhang and his colleagues from the Center for Free-Electron laser Science (CFEL) at DESY present their experimental accelerator in the journal Physical Review X.

The miniature size of the device is possible due to the short wavelength of terahertz radiation. "Terahertz-based accelerators have emerged as promising candidates for next-generation compact electron sources," explains Franz Kärtner, Lead Scientist at DESY and head of the CFEL group that built the device. Scientists have successfully experimented with terahertz accelerators before, which could enable applications where large particle accelerators are just not feasible or necessary. "However, the technique is still in an early stage, and the performance of experimental terahertz accelerators has been limited by the relatively short section of interaction between the terahertz pulse and the electrons," says Kärtner.

For the new device, the team used a longer pulse comprising many cycles of terahertz waves. This multicycle pulse significantly extends the interaction section with the particles. "We feed the multicycle terahertz pulse into a waveguide that is lined with a dielectric material", says Zhang. Within the waveguide, the pulse's speed is reduced. A bunch of electrons is shot into the central part of the waveguide just in time to travel along with the pulse. "This scheme increases the interaction region between the terahertz pulse and the electron bunch to the centimetre range - compared to a few millimetres in earlier experiments," reports Zhang.

The device did not produce a large acceleration in the lab. However, the team could prove the concept by showing that the electrons gain energy in the waveguide. "It is a proof of concept. The electrons' energy increased from 55 to about 56.5 kilo electron volts," says Zhang. "A stronger acceleration can be achieved by using a stronger laser to generate the terahertz pulses."

The set-up is mainly designed for the non-relativistic regime, meaning the electrons have speeds that are not so close to the speed of light. Interestingly, this regime enables a recycling of the terahertz pulse for a second stage of acceleration. "Once the terahertz pulse leaves the waveguide and enters the vacuum, its speed is reset to the speed of light," explains Zhang. "This means, the pulse overtakes the slower electron bunch in a couple of centimetres. We placed a second waveguide at just the right distance that the electrons enter it together with the terahertz pulse which is again slowed down by the waveguide. In this way, we generate a second interaction section, boosting the electrons' energies further."

In the lab experiment, only a small fraction of the terahertz pulse could be recycled this way. But the experiment shows that recycling is possible in principle, and Zhang is confident that the recycled fraction can be substantially increased. Nicholas Mattlis, senior scientist and the team leader of the project in the CFEL group, emphasises: "Our cascading scheme will greatly lower the demand on the required laser system for electron acceleration in the non-relativistic regime, opening new possibilities for the design of terahertz-based accelerators."

The work is funded by the EU Synergy Grant AXSIS (frontiers in Attosecond X-ray Science: Imaging and Spectroscopy) at CFEL. CFEL is a joint venture of DESY, the University of Hamburg and the Max Planck Society.

DESY is one of the world's leading particle accelerator centres and investigates the structure and function of matter - from the interaction of tiny elementary particles and the behaviour of novel nanomaterials and vital biomolecules to the great mysteries of the universe. The particle accelerators and detectors that DESY develops and builds at its locations in Hamburg and Zeuthen are unique research tools. They generate the most intense X-ray radiation in the world, accelerate particles to record energies and open up new windows onto the universe. DESY is a member of the Helmholtz Association, Germany's largest scientific association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 per cent) and the German federal states of Hamburg and Brandenburg (10 per cent).

A previously unknown significant source of carbon just discovered in the Arctic has scientists marveling at a once overlooked contributor to local coastal ecosystems - and concerned about what it may mean in an era of climate change.

In a Nature Communications paper released today, aquatic chemists and hydrologists from The University of Texas at Austin's Marine Science Institute and Jackson School of Geosciences, U.S. Fish and Wildlife Service and Florida State University present evidence of significant, undetected concentrations and fluxes of dissolved organic matter entering Arctic coastal waters, with the source being groundwater flow atop of frozen permafrost. This water moves from land to sea unseen, but researchers now believe it carries significant concentrations of carbon and other nutrients to Arctic coastal food webs.

Groundwater is known globally to be important for delivering carbon and other nutrients to oceans, but in the Arctic, where much water remains trapped in frozen earth, its role has been less clear. Scientists were surprised to learn that groundwater may be contributing an amount of dissolved organic matter to the Alaskan Beaufort Sea that is almost on a par with what comes from neighboring rivers during the summer.

"We have to start thinking differently about groundwater," said senior author Jim McClelland, professor of marine sciences at UT Austin. "The water that flows from rivers to the Arctic Ocean is pretty well accounted for, but until now the groundwater flowing to this ocean hasn't been."

The research community has generally assumed that groundwater inputs from land to sea are small in the Arctic because perennially frozen ground, or permafrost, constrains the flow of water below the tundra surface.

The research published today describes sampling the concentration and age of dissolved carbon, as well as nitrogen, in groundwater flowing beneath the land's surface in the Arctic during the summer. The team found that as shallow groundwater flows beneath the surface at sites in northern Alaska, it picks up new, young organic carbon and nitrogen as expected. However, they also discovered that as groundwater flows toward the ocean, it mixes with layers of deeper soils and thawing permafrost, picking up and transporting century-to-millennia old organic carbon and nitrogen.

This old carbon being transported by groundwater is thought to be minimally decomposed, never having seen the light of day before it meets the ocean.

"Groundwater inputs are unique because this material is a direct shot to the ocean without seeing or being photodegraded by light," McClelland said. "Sunlight on the water can decompose organic carbon as it travels downstream in rivers. Organic matter delivered to the coastal ocean in groundwater is not subject to this process, and thus may be valuable as a food source to bacteria and higher organisms that live in Arctic coastal waters."

The researchers concluded that the supply of leachable organic carbon from groundwater amounts to as much as 70% of the dissolved organic matter flux from rivers to the Alaska Beaufort Sea during the summer.

"Despite its ancient age, dissolved organic carbon in groundwater provides a new and potentially important source of fuel and energy for local coastal food webs each summer," said lead author Craig Connolly, a recent graduate of UT Austin's Marine Science Institute. "The role that groundwater inputs play in carbon and nutrient cycling in Arctic coastal ecosystems, now and in the future as climate changes and permafrost continues to thaw, is something we hope will spark research interest for years to come."

Co-author M. Bayani Cardenas, a professor in the Jackson School of Geosciences, said that climate change's outsized effect on the Arctic makes groundwater research all the more important.

"The Arctic is heating up twice as much as the rest of the planet. With that comes permafrost thawing and the birth of aquifers," he said. "It is likely that groundwater transport in the Arctic will be more and more important in the future."

Electrical and chemical signals flash through our brains constantly as we move through the world, but it would take a high-speed camera and a window into the brain to capture their fleeting paths.

University of California, Berkeley, investigators have now built such a camera: a microscope that can image the brain of an alert mouse 1,000 times a second, recording for the first time the passage of millisecond electrical pulses through neurons.

"This is really exciting, because we are now able to do something that people really weren't able to do before," said lead researcher Na Ji, a UC Berkeley associate professor of physics and of molecular and cell biology.

The new imaging technique combines two-photon fluorescence microscopy and all-optical laser scanning in a state-of-the-art microscope that can image a two-dimensional slice through the neocortex of the mouse brain up to 3,000 times per second. That's fast enough to trace electrical signals flowing through brain circuits.

With this technique, neuroscientists like Ji can now clock electrical signals as they propagate through the brain and ultimately look for transmission problems associated with disease.

One key advantage of the technique is that it will allow neuroscientists to track the hundreds to tens of thousands of inputs any given brain cell receives from other brain cells, including those that don't trigger the cell to fire. These sub-threshold inputs -- either exciting or inhibiting the neuron -- gradually add up to a crescendo that triggers the cell to fire an action potential, passing information along to other neurons.

>From electrodes to fluorescence imaging

The typical method for recording electrical firing in the brain, via electrodes embedded in the tissue, detects only blips from a few neurons as the millisecond voltage changes pass by. The new technique can pinpoint the actual firing neuron and follow the path of the signal, millisecond by millisecond.

"In diseases, many things are happening, even before you can see neurons firing, like all the subthreshold events," said Ji, a member of UC Berkeley's Helen Wills Neuroscience Institute. "We've never looked at how a disease will change with subthreshold input. Now, we have a handle to address that."

Ji and her colleagues reported the new imaging technique in the March issue of the journal Nature Methods. In the same issue, she and other colleagues also published a paper demonstrating a different technique for imaging calcium signaling over much of an entire hemisphere of the mouse brain at once, one that uses a wide-field-of-view "mesoscope" with two-photon imaging and Bessel focus scanning. Calcium concentrations are linked with voltage changes as signals are transmitted through the brain.

"This is the first time anyone has shown in three dimensions the neural activity of such a large volume of the brain at once, which is far beyond what electrodes can do," Ji said. "Furthermore, our imaging approach gives us the ability to resolve the synapses of each neuron."

Synapses are the spots where neurotransmitters are released by one neuron to excite or inhibit another.

One of Ji's goals is to understand how neurons interact across large areas of the brain and eventually locate diseased circuits linked to brain disorders.

"In brain disorders, including neurodegenerative disease, it's not just a single neuron or a few neurons that get sick," Ji said. "So, if you really want to understand these illnesses, you want to be able to look at as many neurons as possible over different brain regions. With this method, we can get a much more global picture of what is happening in the brain."

Two-photon microscopy

Ji and her colleagues are able to peer into the brain thanks to probes that can be pinned to specific types of cells and become fluorescent when the environment changes. To track voltage changes in neurons, for example, her team employed a sensor developed by co-author Michael Lin of Stanford University that becomes fluorescent when the cell membrane depolarizes as a voltage signal propagates along the cell membrane.

The researchers then illuminate these fluorescent probes with a two-photon laser, which makes them emit light, or fluoresce, if they have been activated. The emitted light is captured by a microscope and combined into a 2D image that shows the location of the voltage change or the presence of a specific chemical, such as the signaling ion, calcium.

By rapidly scanning the laser over the brain, much like a flashlight that gradually reveals the scene inside a darkened room, researchers are able to obtain images of a single, thin layer of the neocortex. The team was able to conduct 1,000 to 3,000 full 2D scans of a single brain layer every second by replacing one of the laser's two rotating mirrors with an optical mirror -- a technique called free-space angular-chirp-enhanced delay (FACED). FACED was developed by paper co-author Kevin Tsia at the University of Hong Kong.

The kilohertz imaging not only revealed millisecond changes in voltage, but also more slowly changing concentrations of calcium and glutamate, a neurotransmitter, as deep as 350 microns (one-third of a millimeter) from the brain's surface.

To obtain rapid 3D images of the movement of calcium through neurons, she combined two-photon fluorescent microscopy with a different technique, Bessel focus scanning. To avoid time-consuming scans of every micron-thick layer of the neocortex, the excitation focus of the two-photon laser is shaped from a point to a small cylinder, like a pencil, about 100 microns in length. This pencil beam is then scanned at six different depths through the brain, and the fluorescent images are combined to create a 3D image. This allows more rapid scanning with little loss of information because in each pencil-like volume, typically only one neuron is active at any time. The mesoscope can image an area about 5 mm in diameter -- nearly a quarter of one hemisphere of the mouse brain -- and 650 microns deep, close to the full depth of the neocortex, which is involved in complex information processing.

"Using conventional methods, we would have to scan 300 images to cover this volume, but with an elongated beam that collapses the volume onto a single plane, we only need to scan six images, which means that now we can have a fast enough volumetric rate to look at its calcium activity," Ji said.

Ji is now working on combining four techniques -- two-photon fluorescence microscopy, Bessel beam focusing, FACED and adaptive optics -- to achieve high-speed, high sensitivity images deep in the neocortex, which is about 1 millimeter thick.

"As a way to understand the brain, my dream is to combine these microscopy techniques to get submicron spatial resolution so we can see the synapses, millisecond time resolution for the voltage imaging, and see all of this deep in the brain," she added. "What is complicated and challenging about the brain is that, if you only do one single optical section, in a way you don't get a complete picture, because a neural network is very much three-dimensional."