|Российская наука и мир|
(по материалам зарубежной электронной прессы)
Eurasia Review / December 7, 2016
GeroScope: A Computer Method To Beat Aging
Российские учёные из МФТИ совместно с международной компанией Insilico Medicine (занимается проблемами старения) разработали программу GeroScope, способную анализировать эффективность геропротекторов - средств, предположительно увеличивающих продолжительность жизни. Алгоритм также может использоваться для поиска ещё неизвестных веществ с геропротекторными свойствами.
Russian scientists from MIPT, in collaboration with Insilico Medicine Inc., were commissioned by the Center for Biogerontology and Regenerative Medicine to develop the GeroScope algorithm to identify geroprotectors - substances that extend healthy life. Hundreds of compounds were screened for geroprotective activity using computer simulations, and laboratory experiments were conducted on the ten substances that were identified using this algorithm.
A research paper detailing the results of the study has been published in one of the top peer-reviewed journals in aging research, Aging.
Decades of hard work by highly-competent research teams and millions of dollars are spent on the process of developing new drugs. And the screening and development process of geroprotectors, interventions intended to combat aging, a complex multifactorial biological process affecting every cell in the human body, is even more tedious. Computer modeling techniques may significantly reduce the time and cost of development.
"The aging of the population is a global problem. Developing effective approaches for creating geroprotectors and validating them for use in the human body is one of the most important challenges for biomedicine. We have proposed a possible approach that brings us one step closer to solving this problem," said Alexey Moskalev, a corresponding member of the RAS and head of the Laboratory of Genetics of Aging and Longevity.
For several years the group studied cancer-related processes and relied on the Oncofinder, an algorithm designed to study and analyze the activation values of molecular pathways by comparing gene expression in cancerous and normal healthy cells, and also comparing tissue samples of different patients. The researchers applied a similar approach to develop GeroScope, which is able to compare changes in the cells of young and old patients and search for drugs with minimal side effects that compensate for these changes.
To do this, the scientists analyzed transcriptomic data (information which is read from DNA and transcribed into RNA) in "young" (donors aged between 15 and 30 years) and "old" (donors over the age of 60) samples from many human tissue types. This data was used for advanced computer modeling to identify and re-construct the molecular pathways associated with aging. Molecular pathways are a sequence of reactions that lead to changes in a cell. The most common molecular pathways are involved in metabolism and signal transduction. GeroScope modeled molecular pathways and analyzed cell reactions to various substances. Having chosen 70 compounds from the database of geroprotective drugs, previously published by the research group in a paper titled "Geroprotectors.org: a new, structured and curated database of current therapeutic interventions in aging and age-related disease," the scientists used the new algorithm to identify 10 substances that could have geroprotector properties in accordance with the model.
The GeroScope model was used to analyze the tissues of young and old patients, as well as cell lines. In order to experimentally verify the algorithm, the scientists took stem cell lines of human fibroblasts (connective tissue cells). Two effects were studied: cell "rejuvenation" and survival.
The experiments started with the measurement of the many parameters of viable cells: the size, shape, and complexity of the internal structure of the cell etc. The cells were then mixed with a test substance and a growth medium and held in this state for 6, 12, and 18 days. The scientists then measured the same parameters as at the start of the experiment, as well as the level of associated β-galactosidase, which is considered one of the markers of aging.
The 10 test substances chosen by the computer model demonstrated different results in human cell assays. For example, NDGA has no effect on rejuvenation, but it does decrease short- and long-term survival, Myricetin has a mild rejuvenating effect and EGCG has a strong rejuvenating effect. NAC has a very mild rejuvenating effect, but dramatically increases short- and long-term survival, PD-98059 has a very strong rejuvenating effect and increases both short- and long-term survival.
The predictions made by the computer model were confirmed in cell cultures of human fibroblasts for several substances: PP-98059, NAC, Myricetin and EGCG. Some of these drugs are already actively sold as dietary supplements individually. Further analysis of the pathway-level effects of many of these compounds provided insights into the possible combinations providing maximal cumulative effects and minimizing the possible adverse effects.
"For computer modeling this is a very good result. In the pharmaceutical industry, 92% of drugs that are tested on animals fail during clinical trials in humans. The ability to simulate biological effects with such a high level of accuracy in silico is a real breakthrough. PD-98059 and NAC proved to be the strongest geroprotectors. We hope that some of these drugs will soon be tested on people using biologically-relevant biomarkers of aging," said Alex Zhavoronkov Ph.D., head of the Laboratory of Regenerative Medicine at the D. Rogachev Federal Research and Clinical Center for Pediatric Hematology, Oncology, and Immunology, an adjunct professor at MIPT, and head of Insilico Medicine Inc. (Emerging Technology Centers located at the Johns Hopkins University at Eastern Campus).
Earlier this year Alexey Moskalev and Alex Zhavoronkov collaborated on applying the deep learning techniques to develop cost-effective biomarkers of aging on one of the most abundant data types from simple blood tests, Putin E, et al, "Deep biomarkers of human aging: Application of deep neural networks to biomarker development". These and other biomarkers developed using deep learning techniques commonly referred to as artificial intelligence will be applied to validating the effects of geroprotectors in humans.
The GeroScope algorithm developed for geroprotector screening has thus been successfully validated using series of experiments on human cells. A high correlation was demonstrated between the predictions made by the algorithm and experimental data. GeroScope will later be used to search for unknown substances with geroprotective effects as well as for compounds that may be used to treat a variety of the age-related conditions.
Copyright 2016 | By Eurasia Review.
* * *
Electronic Component News Magazine / 13.12.2016
Two Electrons Go On A Quantum Walk And End Up In A Qudit
Учёные из Физико-технологического института РАН и МФТИ создали элемент квантового компьютера более высокой размерности, чем обычные кубиты (квантовые биты).
Соединить несколько кубитов в систему очень трудно из-за того, что связь между ними неустойчива, поэтому физики попытались разместить большое количество ячеек квантовой информации внутри одного кубита, воспользовавшись так называемыми "заблудившимися" электронами. В итоге получился "кудит" - квантовая структура, которая может находиться не в двух, а в трех и более состояниях, что позволяет уменьшить число элементов в квантовых компьютерах и тем самым сделать возможным их создание на практике.
Scientists from the Institute of Physics and Technology of the Russian Academy of Sciences and MIPT have let two electrons loose in a system of quantum dots to create a quantum computer memory cell of a higher dimension than a qubit (a quantum bit). In their study published in Scientific Reports, the researchers demonstrate for the first time how quantum walks of several electrons can help to implement quantum computation.
"By studying the system with two electrons, we solved the problems faced in the general case of two identical interacting particles. This paves the way toward compact high-level quantum structures," comments Leonid Fedichkin, Expert at the Russian Academy of Sciences, Vice-Director for Science at NIX (a Russian computer company), and Associate Professor at MIPT's Department of Theoretical Physics.
In a matter of hours, a quantum computer would be able to hack through the most popular cryptosystem used even in your web browser. As far as more benevolent applications are concerned, a quantum computer would be capable of molecular modeling that takes into account all interactions between the particles involved. This in turn would enable the development of highly efficient solar cells and new drugs. To have practical applications, a quantum computer needs to incorporate hundreds or even thousands of qubits. And that is where it gets tricky.
As it turns out, the unstable nature of the connection between qubits remains the major obstacle preventing us from using quantum walks of particles for quantum computation. Unlike their classical analogs, quantum structures are extremely sensitive to external noise. To prevent a system of several qubits from losing the information stored in it, liquid nitrogen (or helium) needs to be used for cooling. Plenty of schemes have been proposed for the experimental realization of a separate qubit. In an earlier study, a research team led by Prof. Fedichkin demonstrated that a qubit could be physically implemented as a particle "taking a quantum walk" between two extremely small semiconductors known as quantum dots, which are connected by a "quantum tunnel." From the perspective of an electron, the quantum dots represent potential wells. Thus, the position of the electron can be used to encode the two basis states of the qubit-|0? and |1?- depending on whether the particle is in one well or the other. Rather than sit in one of the two wells, the electron is smeared out between the two different states, taking up a definite position only when its coordinates are measured. In other words, it is in a superposition of two states.
If an entangled state is created between several qubits, their individual states can no longer be described separately from one another, and any valid description must refer to the state of the whole system. This means that a system of three qubits has a total of 8 basis states and is in a superposition of them: A|000?+B|001?+C|010?+D|100?+E|011?+F|101?+G|110?+H|111?. By influencing the system, one inevitably affects all of the 8 coefficients, whereas influencing a system of regular bits only affects their individual states. By implication, n bits can store n variables, while n qubits can store 2? variables. Qudits offer an even greater advantage, since n four-level qudits (aka ququarts) can encode 4?, or 2?×2? variables. To put this into perspective, 10 ququarts store approximately 100,000 times more information than 10 bits. With greater values of n, the zeros in this number start to pile up very quickly.
In this study, Alexey Melnikov and Leonid Fedichkin obtain a system of two qudits implemented as two entangled electrons quantum-walking around the so-called cycle graph. To make one, the scientists had to "connect the dots" forming a circle (once again, these are quantum dots, and they are connected by the effect called quantum tunneling). The entanglement of the two electrons is caused by the mutual electrostatic repulsion experienced by like charges. It is possible to create a system of even more qudits in the same volume of semiconductor material. To do this, it is necessary to connect quantum dots in a pattern of winding paths and have more wandering electrons. The quantum walks approach to quantum computation is convenient because it is based on a natural process. Nevertheless, the presence of two identical electrons in the same structure was a source of additional difficulties that had remained unsolved.
The phenomenon of particle entanglement plays a pivotal role in quantum information processing. However, in experiments with identical particles, it is necessary to distinguish so-called false entanglement, which can arise between electrons that are not interacting, from genuine entanglement. To do this, the scientists performed mathematical calculations for both cases, viz., with and without entanglement. They observed the changing distribution of probabilities for the cases with 6, 8, 10, and 12 dots, i.e., for a system of two qudits with three, four, five, and six levels each. The scientists demonstrated that their proposed system is characterized by a relatively high degree of stability.
It has been a long time since people first set their hearts on building a universal quantum computer, but so far we have been unable to connect a sufficient number of qubits. The work of the Russian researchers brings us one step closer to a future where quantum computations are commonplace. And although there are algorithms that quantum computers could never accelerate, others would still benefit enormously from devices able to exploit the potential of large numbers of qubits (or qudits). These alone would be enough to save us a couple of thousand years.
© Copyright 2016 Advantage Business Media.
* * *
EurekAlert / 19-Dec-2016
An ancient mechanism helps a cell to resist stress
Scientists have demonstrated how an evolutionary ancient mechanism of protein biosynthesis helps a cell to resist stress.
Обычно в живую клетку доставляют ДНК, которая, проникнув в ядро, запускает процессы синтеза новых РНК, а те, в свою очередь, начинают участвовать в производстве белков. Биологи из Научно-исследовательского института физико-химической биологии имени А.Н.Белозерского МГУ и Института молекулярной биологии им. В.А.Энгельгардта РАН воспользовались методом трансфекции для доставки в живую клетку сразу РНК. Это позволило изучить влияние клеточного стресса на биосинтез белка на более коротких временных промежутках.
Biologists from the Lomonosov Moscow State University in collaboration with colleagues from the Engelhardt Institute of Molecular Biology, Russian Academy of Sciences used RNA transfection and in vitro techniques to show how the same mRNA can direct protein synthesis in a cell by four different means. The research results have been published in a peer reviewed journal Scientific Reports.
Scientists from the Belozersky Institute of Physico-Chemical Biology, a department of the Lomonosov Moscow State University, along with their colleagues, have applied a transfection method to deliver RNA into the cell that has allowed them to study the impact of cell stress on protein biosynthesis on a short-time scale.
Cell stress and reprogramming of protein synthesis
Sergey Dmitriev, Senior Researcher at the Belozersky Institute of Physico-Chemical Biology, the Lomonosov Moscow State University and the Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, being a leading author of the article, shares the following comments. He says: "Our project is devoted to the studies of protein biosynthesis mechanisms, including the situations of cell stress. The research highlights three aspects. The first one concerns methods as we present a technique, which allows analyzing protein synthesis in a cell with the help of a short-term RNA transfection technique".
Transfection is a method of DNA and RNA delivery to a living cell. Usually DNA is used: after entrance into the nucleus it initiates the processes of new RNA synthesis, and only afterwards the RNAs are exported into cytoplasm and can participate in protein production. Biologists from the Lomonosov Moscow State University propose a methodology of introducing an artificially synthesized RNA into the cell, so it could become a template for protein synthesis immediately. RNA is delivered to cells with the help of a special chemical agent. Once penetrated into cytoplasm, it's released and gets ready to participate in protein production; the only thing left to do for the RNA is to meet a ribosome. So, the way to the final product becomes much shorter. In as little as 1 or 2 hours one could observe protein activity and estimate its quantity.
This technique allows studying the impact of a stress on the cell in a short-time scale. To cell stresses one could refer, for example, heat shock, caused by elevated temperature; oxidative stress, provoked by reactive oxygen species; response to chemical agents, which disrupt homeostasis (including antibiotics and medical drugs). Factors of cell stress compel the cell to suspend protein biosynthesis (or "reprogram" it), until the system redresses the balance.
Sergey clarifies: "Usually these processes last from one to four hours, and our technique of "fast" RNA transfection is the most convenient way to study the effect of these processes. We've conducted our research on cultured cells of human kidney, which serve as a standard model for such studies. Finally, we have elaborated a technique that allows one to obtain artificial RNA, transfer it into cells and obtain the result in a very short period of time. We've named the whole method FLERT (for "fleeting mRNA transfection"), which sounds in Russian a bit like flirtation,"- adds Sergey and smiles.
Why is the sum of 40S and 60S equal to 80S in case of a ribosome?
Messenger RNA (mRNA) is a polymer of nucleotides, coding for a protein. One amino acid is encoded by 3 nucleotides. There is a special molecular machine, called ribosome, existing in the cell for protein production. Moving along mRNA, the ribosome reads information in a triplet by triplet manner.
The structure of the protein synthesis machine is very complicated. It comprises two subunits: a small one (40S) and a large one (60S). A whole ribosome is obtained when they join. However, it's specified not as 100S, but as 80S. The reason is that these figures refer not to the particle mass, but to the sedimentation coefficient, determined during centrifugation. This coefficient depends on several parameters, including the shape of a particle.
In order to start information decoding, first of all it is necessary to find the right starting point - a triplet from which the reading begins. Detection of the starting point is problematic, as there are no marks for triplets in mRNA. However, if you start reading from a wrong nucleotide, the reading frame will be shifted, and everything will go wrong. Special proteins (translation initiation factors) help the ribosome to find the right place in the template to start reading triplets.
Usually there is a distance between the beginning of the mRNA chain and the starting point, called "leader". A ribosome should pass this leader by, without reading. Russian scientists have decide to check what will happen if mRNA will begin right with the start codon - from the "first word". It's interesting that in archaea (single-celled prokaryotic organisms, which have been living on the Earth for billion years and are capable of surviving in extreme conditions) and some other primitive organisms most mRNAs begin right from the start codon. Such RNAs are called leaderless. Leaderless mRNAs are supposed to be an evolutionary prototype of messenger RNAs because ancient ribosomes were not able to find starting points and initiated decoding from the very beginning of the mRNA chain.
A ribosome is to pass through several phases in order to interact with mRNA and start protein synthesis. Normally, at first the 40S subunit of the ribosome binds mRNA, and then the large 60S subunit joins it at the start codon. In contrast, the leaderless mRNA can be loaded directly into the whole ribosome. This discovery was made in the 90-s by Ivan Shatsky, Professor from the Lomonosov Moscow State University.
In the new project scientists have demonstrated that due to their unique properties, leaderless RNAs are resistant to many stress types and continue directing protein synthesis even in such conditions, when common RNAs with leader stop working in the first minutes after the impact. With the help of FLERT technique scientists have shown this in living cells.
All ways are OK - you can choose whatever you like
The research extension has brought even more interesting results. It has been turned out that unique properties of the leaderless mRNA provide it with high flexibility in the choice of protein synthesis mechanisms.
It has been found out that eukaryotes possess several pathways by which a ribosome could find itself on the start codon. These modes are mediated by distinct sets of specialized proteins - called translation initiation factors - and have been shown to operate on different mRNAs.
The most common pathway, which could be used by any cellular mRNA, is provided by eIF2 protein. However, this factor is very quickly inactivated under conditions of stress. As a result, ribosomes fail to recognize the start codons on all mRNAs, except those that use other initiation factors.
Later on scientists discovered that eIF2 is not the only factor able to do this work. For instance, mRNA of hepatitis C virus is capable of doing without eIF2 and can use other factors, eIF5B or eIF2D, instead (this discovery was also made by scientists from the Lomonosov Moscow State University earlier). This virus was supposed to be unique in this sense - while canonical templates are passively waiting until a ribosome binds them, the hepatitis C virus mRNA "grasps" 40S subunit and "puts" it to the right place in the chain. This unusual property makes possible the usage of alternative ways. And now scientists have proved that the leaderless mRNA is capable of acting in the same way.
It's also interesting that all organisms possess eIF5B factor as it's an evolutionary conserved protein. In contrast, eIF2 exists only in eukaryotes and archaea - so, it's not universal. All the above mentioned results allow to say that the well-studied classical factor eIF2 is needed only if ribosomes recognize mRNA by active searching for the start codon. Such mean of translation initiation is called scanning and requires eIF2. When the start codon is found, eIF2 is replaced by eIF5B and protein synthesis starts. More evolutionary-ancient leaderless mRNA can use a primitive mechanism, immediately recruiting eIF5B factor.
Sergey Dmitriev concludes: "We've got a nice result, which has explained everything. We've found out that a primitive mRNA could use an evolutionary ancient mechanism. Moreover, it is capable of using the other three pathways: through eIF2, eIF2D or direct recruitment of the whole 80S ribosome".
Copyright © 2016 by the American Association for the Advancement of Science (AAAS).
* * *
3ders.org / Dec 29, 2016
Russian scientist says 3D printed satellite entering orbit in 2017
Первый российский наноспутник "Томск-ТПУ-120" с напечатанными на 3D-принтере элементами корпуса будет запущен в 2017 году с Международной космической станции. Аппарат разработан в Томском политехническом университете совместно с РКК "Энергия" и Институтом физики прочности и материаловедения СО РАН.
Alexey Yakovlev, head of the Institute of High Technologies at Tomsk Polytechnic University in Russia, has just given an update on the groundbreaking Tomsk-TPU-120, a fully 3D printed CubeSat that will be placed into orbit in 2017.
Back in April 2016, a group of scientists at Tomsk Polytechnic University had huge cause for celebration. The Tomsk-TPU-120, an incredible 3D printed micro-satellite developed by those scientists, had just arrived safely at the International Space Station, having been carried there aboard the Progress MS-02. In May, the 3D printed satellite sent test messages down to Tomsk Polytechnic to celebrate the university's 120th anniversary. All was going to plan.
Half a year on, and the Siberian scientists behind the Tomsk-TPU-120 satellite are preparing for an even more exciting prospect: deploying the 3D printed CubeSat into orbit. According to the group, the satellite will be sent into the atmosphere during a spacewalk by Russian cosmonauts - hence the prominent handle on the device - sometime in July 2017. And if everything goes to plan, the Russian space experts may then create several more 3D printed satellites.
According to Alexey Yakovlev, head of the Tomsk Polytechnic University's Institute of High Technologies, the 3D printed satellite is something of a landmark for additive manufacturing, being the first example of a fully 3D printed satellite: "The Tomsk-TPU-120 is the first such project in the world, in which the entire casing of a satellite is fully 3D printed using dynamic modeling," Yakovlev recently told Sputnik. "The combination of these technologies can significantly reduce the development time and the number of full-scale tests, find new engineering solutions, and reduce the project's cost."
In addition to its cost-saving potential, additive manufacturing has also enabled the Tomsk scientists to eke out further advantages from the Tomsk-TPU-120. For one, the 3D printed materials have made the satellite lightweight, robust, and able to resist vibrations. And secondly, those material advantages have opened up practical opportunities for the satellite: Yakovled has revealed that the 3D printed CubeSat could yet become part of a huge group of similar satellites that could be used to monitor agriculture, forest fires, climate change, and natural resources. "The current project is just the first stage of a long-term project to develop and create small, multi-purpose satellites," Yakovled said.
The 3D printed satellite is now almost ready for its July 2017 deployment, but getting to that stage has required a great deal of time and effort from the Siberian satellite experts - and from other helpful contributors too. After experiments with the satellite were conducted not only on board the ISS, but also on the ground, the Tomsk scientists were able to depend upon friendly collaborators from across the world to give updates on the satellite's broadcasting status. "Many radio amateurs from all across the world were able to catch a satellite signal on their radio stations, and posted videos of it on the Internet," Yakovled reported.
Although the Tomsk scientists are hopeful that their 3D printed satellite will prove advantageous for the entire scientific community, they have also recognized that the deployment of the 3D printed capsule will be a difficult and expensive task, one that will need to be preceded by "repair or modernization" of the outer surface of the ISS. After being put into orbit, however, the CubeSat will be in free flight for around six months, eventually entering dense layers of the atmosphere where it will be destroyed.
As July 2017 approaches, we'll be sure to keep a close eye on the progress of the Tomsk-TPU-120.
© Copyright © 2011-2017. www.3Ders.org. All Rights Reserved.
* * *
EurekAlert / 29-Dec-2016
Diamonds are technologists' best friends
Researchers from the Lomonosov Moscow State University have grown needle- and thread-like diamonds and studied their useful properties.
Физики из МГУ вырастили игольчатые и нитевидные кристаллы алмаза размером в несколько микрометров и изучили их люминесцентные и электронно-эмиссионные свойства. Кристаллы такой формы необходимы во многих технологиях, но прежде их получали, отделяя фрагменты нужной формы от большого кристалла. Новый способ гораздо менее затратен.
Physicists from the Lomonosov Moscow State University have obtained diamond crystals in the form of a regular pyramid of micrometer size. Moreover, in cooperation with co-workers from other Russian and foreign research centers they have also studied the luminescence and electron emission properties of obtained diamond crystals. The research results have been represented in a series of articles published in the leading peer review journals, the most recent appeared in Scientific Reports.
Researchers from the Faculty of Physics, the Lomonosov Moscow State University, have described structural peculiarities of micrometer size diamond crystals of needle- and thread-like shapes, and their interrelation with luminescence features and efficiency of field electron emission. The luminescence properties of such thread-like diamond crystals could be used in different types of sensors, quantum optical devices and also for creation of element base for quantum computers and in other areas of science and technology.
The best friends of girls and technologists
Brilliants are polished rough diamond crystals and glorified as "a girl's best friend". Wide use of diamonds in various industrial processes is relatively less famous among ordinary people. However, technological application of diamonds significantly outweighs their jewelry usage and is constantly increasing both in terms of quantity and enhancing the diversity of areas of their application. Such high application significance turns out to be a constant motivation for researchers, busy with elaboration of new methods of diamond synthesis, processing and enduing with necessary features.
One of the problems, which are to be solved for a number of technology developments, is production of needle- and thread-like diamond crystals. Such shaping of original natural and synthetic diamonds is possible due to man-handling (polishing) in the same way as it happens during brilliant production. Other means imply usage of lithography and ion beam technologies, which help to separate fragments of necessary shape from crystals of large size. However, such "cutting" techniques are quite expensive and not always acceptable.
A team of researchers, working at the Faculty of Physics of the Lomonosov Moscow State University under the guidance of Professor Alexander Obraztsov, has suggested a technology, which makes possible mass production of small diamond crystals (or crystallites) of needle- and thread-like shapes. The first results, got during the studies in this direction, were published seven years ago in Diamond & Related Materials journal.
Alexander Obraztsov, Professor at the Department of Polymer and Crystal Physics, at the Faculty of Physics of the Lomonosov Moscow State University; Doctor of Science in Physics and Mathematics, being the main research author shares the following comments. He says: "The proposed technique involves usage of a well-known regularity, determining formation of polycrystalline films from crystallites of elongate ("columnar") shape. For instance, ice on a surface of lake often consists of such crystallites, what could be observed while it's melting.
Usually, during diamond polycrystalline films production, one strives to provide such conditions, which allow crystallites of columnar shape, composing the films, to tightly connect with each other, creating dense homogeneous structure".
Everything, except diamonds, is gasified
Researchers from the Lomonosov Moscow State University have shown that diamond films, which have been previously perceived as "bad quality" ones as they consist of separate crystallites, not connecting with each other, now could be used for production of diamonds in the form of needle- or thread-like developments of regular pyramid form. In order to achieve this, it's necessary to heat such films to definite temperature in air or in another oxygen-containing environment. When heated, a part of the film material begins oxidizing and gasifies. Due to the fact that oxidation temperature depends on the carbon material features, and diamond crystallites oxidation need maximum temperature, it's possible to adjust this temperature so that all the material, except these diamond crystallites, is gasified. This relatively simple technology combines production of polycrystalline diamond films with specified structural characteristics with their heating in the air. It makes possible mass production of diamond crystallites of various shapes (needle- and thread-like ones and so on). Some idea about such crystallites can be obtained from electron microscopy images. The crystallites could be used, for instance, as high hardness elements: a cutter for high- precision processing, indenters or probes for scanning microscopes. Such application was described in the article, published earlier by the team in journal Review of Scientific Instruments. At the moment all probes, produced using this technology, are commercially offered.
It's possible to manage useful properties of a diamond
During follow-up research and developments, conducted at the Faculty of Physics, the Lomonosov Moscow State University, the initial technology has been significantly improved, what has allowed to diversify shapes and sizes of the needle-like crystallites and extend prospective field of their application. Researchers from the Lomonosov Moscow State University have drawn attention to optical properties of a diamond, which are of significant fundamental scientific and applied interest. The results of these studies are represented in the series of articles in Journal of Luminescence, Nanotechnology, and Scientific Reports.
These recent publications describe structural peculiarities of such diamond crystallites and their interrelation with luminescence features and efficiency of field electron emission. As it is mentioned by the researchers, the latter is, probably, the first example of genuine diamond field-emission (or cold) cathode realization. Many efforts have been made for its obtaining and studying of such kind of cathodes for the last two decades. Luminescence properties of the needle-like diamond crystals could be applied in different types of sensors, quantum optical devices and also in creation of element base for quantum computers and in other areas of science and technology.
Alexander Obraztsov further notices: "I'd especially like to highlight the significant input of young researchers - Viktor Kleshch and Rinat Ismagilov - to these studies. Their enthusiasm and intense work have allowed to get the above described results, which are truly new and possess fundamental scientific and applied importance".
The studies have been conducted with support of the Russian Science Foundation.
Copyright © 2017 by the American Association for the Advancement of Science (AAAS).
* * *
Ouest-France / Le 29/12/2016
Des mantes religieuses en Sibérie
Климатические изменения привели к тому, что биологи из Тюменского государственного университета обнаружили в своем регионе богомолов, никогда здесь прежде не водившихся.
Des chercheurs russes et allemands ont observé l'arrivée d'insectes du sud, à Tioumen. Le climat change aussi en Russie...
Il n'y a guère plus que l'Américain Donald Trump pour contester le réchauffement climatique, ou l'attribuer aux Chinois. Des chercheurs de l'Université de Tioumen, berceau du célèbre Raspoutine, viennent de découvrir des invertébrés des steppes du sud en Sibérie occidentale.
« En raison du changement climatique, des arthropodes méridionaux sont en train de monter vers le nord de la Sibérie. Nous venons d'observer des mantes religieuses, une espèce que nous n'avions jamais vue dans la région », explique Igor Kuzmin, professeur du département de biologie. La majorité de ces insectes à carapace a été trouvée dans des endroits modifiés par l'activité humaine : des champs, des jardins, au centre des villes, « zones où ces petits animaux rencontrent moins de prédateurs ».
Le climat de Tioumen, capitale pétrolière de la vaste plaine de Sibérie occidentale, située à plus de 1 700 km à l'est de Moscou, a aussi surpris les universitaires allemands de Münster, en Rhénanie-du-Nord-Westphalie. « Dans cette région frontière entre les steppes sèches et la taïga, prospère une richesse incroyable de papillons, dont beaucoup sont au bord de l'extinction en Europe centrale, témoigne l'écologue allemande Fritzi Kunz. Contrairement à ce que l'on croit, il ne fait pas que froid ici. Le thermomètre descend certes à moins 40 °C l'hiver, mais il grimpe à 30 °C l'été ! »
Depuis 2012, les universités de Tioumen et de Münster travaillent ensemble sur le projet Sascha : il vise à engranger les connaissances sur les ressources naturelles de cette région afin d'adapter les terres agricoles au changement climatique.
* * *
The Marshalltown / 2016-12-31
Russian physicists have measured the loss of dark matter since the birth of the universe
Российские физики подсчитали, что с момента Большого Взрыва 13,7 млрд лет назад количество темной материи во Вселенной уменьшилось примерно на 5%. Это может объяснить расхождение в значении некоторых важных космологических параметров ранней Вселенной и современной.
Статья "Dark matter component decaying after recombination: Lensing constraints with Planck data" опубликована в журнале Physical Review D.
Science says that most of the matter in the universe is dark. This dark matter is something they have yet to observe directly because it does not interact with regular matter in any way. Its presence is only felt through its gravitational effects.
Scientists also know that the proportion of dark matter has decreased since the birth of universe but they had never been able to measure the exact amount until now. Using data from observations of various cosmological effects, researchers estimate that universe has lost up to 5% of dark matter since the Big Bang some 13.7 billion years ago.
"The discrepancy between the cosmological parameters in the modern Universe and the Universe shortly after the Big Bang can be explained by the fact that the proportion of dark matter has decreased. We have now, for the first time, been able to calculate how much dark matter could have been lost and what the corresponding size of the unstable component would be." Co-author Igor Tkachev, the Institute for Nuclear Research (INR) of the Russian Academy of Sciences said.
Dark matter was first theorized back in the 1930s when Swiss astronomer Fritz Zwicky observed weird movement of a cluster of galaxy, suggesting that it was under the effect of gravity from an unseen source. The source was undetectable expect for its gravitational effect. Thus, it was given the name dark matter. It was estimated that the dark matter accounts for 26.8% of total matter in the universe, 4.9% of ordinary matter while the rest is dark energy (68.3%). Dark matter is also held responsible for the expansion of universe.
Despite all that, researchers still know very little about the nature of dark matter. When a team of Russian researchers studied observations from Planck telescope - which looks at fluctuations of cosmic microwave background or the "echo" of Big Bang - they noticed a problem there. Fluctuations showed huge difference in the cosmological parameters from the observable universe today compared with that seen in ancient universe. The findings suggest that the composition of earlier universe right after the Big Bang was considerably different from the modern one.
"This means that in today's universe there is 5% less dark matter than in the recombination era," said Tkachev. "We are not currently able to say how quickly this unstable part decayed; dark matter may still be disintegrating even now, although that would be a different and considerably more complex model."
Copyright © 2011-2016 All Rights Reserved.
* * *