Tag: Russia

Scientists of Tomsk Polytechnic University jointly with their colleagues from Great Britain have proposed a physical concept of a new optical switch that forces to change light wave guidance.  The switch is a small glass particle of an unusual form.

Its size is only about 1 µ. The research findings are published in the Annalen der Physik academic journal (IF: 2,276; Q1). According to the authors, such a simple switch can be used in high-speed optical computers in the long run.

Information is transferred by electrons in all currently existent calculating machines, including computers. Scientists believe if electrons inside the computers are replaced with photons, i.e. light quantum, then the data can be transferred literally at lightspeed. Researchers and companies of different countries are working on creating an efficient optical quantum computer.

Prototypes of such computers have already been presented in the USA and China, however, these computers are capable to solve a very limited range of tasks. To widely apply optical computers, researchers still have to overcome a lot of obstacles.

“In such machines, it is essential to switch a signal at very high speed, i.e. to change the light guidance. Therefore, efficient switches are required. Researchers solve this task in different ways. Some researchers propose mechanical switches, however, these switches do not provide the required switching speed. While the others use specific crystals based on the nonlinear effects, which require developing new special materials and methods of controlling them,” Oleg Minin, Professor of the Division for Electronic Engineering of the TPU School of Non-Destructive Testing, a supervisor of the project, says.

“We proposed another principle in our article: particles of special forms from dielectric material can change the light guidance efficiently. In this case, we considered glass. Moreover, the proposed method does not require the application of metals.” Oleg Minin continues.

The proposed switch is a small cube-shaped glass particle with a prism attached to it. Its operation is based on the effect of the photonic hook that was previously discovered by the research authors.

“It is a matter of a particle shape. Previously, we discovered that the light percolating a dielectric particle of this shape twists as a hook at the output. Due to its physical properties, the photonic hook possesses a very wide range of potential applications. In this case, the calculations show if we change the light wavelength percolating the particle, then it is possible to change hook guidance.  That is the core of switching the signal, in changing the guidance,” Oleg Minin notes.

The researchers are currently preparing to conduct a series of experiments, which will prove the results of the simulation and calculations. The experiments will be conducted at Bangor University (Great Britain).

The research was conducted with the partial support of the Russian Foundation for Basic Research and the TPU Competitiveness Enhancement Program.

Scientists of Tomsk Polytechnic University have developed a methodology for forecasting forest fires on the example of the surroundings of Lake Baikal. The methodology is based on an atmospheric soil measuring complex (ASMC).

The research was supported by the grant of the Russian Foundation for Basic Research No. 17-29-05093. The research findings are published in the International Journal on Engineering Applications.

Since 2018, the project has been implemented under the supervision of Nikolay Baranovsky, Associate Professor of the TPU Butakov Research Center. The project aimed at developing techniques for monitoring of inflammability of forests in the conditions of human impact on the area of Lake Baikal basin.

“Lake Baikal is the largest natural reservoir of fresh water and characterized by unique flora and fauna. The lake life cycle is mainly dependent on the processes occurring in the coastal area: natural and human, including forest fires. It can influence the lake drainage and change the regime of its functioning. Therefore, assessment of forest fire break-out from human impact is crucial for understanding the processes influencing the activity of Lake Baikal,” Nikolay Baranovsky notes.

Scientists of Tomsk Polytechnic University, Gorno-Altaisk State University, Institute of Physical Materials Science of the Siberian Branch of the Russian Academy of Sciences, Institute of General and Experimental Biology of the Siberian Branch of the Russian Academy of Sciences and Paris Diderot University (France) took part in the research work.

Using the ASMC, the researchers conducted monitoring of meteorological conditions and soil characteristics, i.e. they recorded the air humidity and temperature, speed and wind direction, the amount of rain precipitation and soil temperature.

The measurements were carried out in the surrounding of Khurumsha (a rural locality in the Republic of Buryatia). The data of some specific days of summer 2019 were used to conduct the research. Based on these data, the scientists offered to use a number of mathematical formulas to assess fire danger.

“The analysis of data has shown that there may be a situation in the forest area when a ground fire turns into a crown fire. Some special conditions are required for that.

First, the canopy of a forest stand must possess the sufficiently small value of the lower limit of the branch position. Second, the speed of the ground fire must be quite fast. It mainly depends on the wind speed inside the forest area.

In this case, the wind is a driver of turning the ground fire into the crown fire. Presumably, there will be various values of critical wind speed for miscellaneous types of forest areas. This problem requires additional study,” Nikolay Baranovky explains.

Despite the fact that the project possesses a fundamental character, the scientists claim the research findings can form the basis of applied developments. In particular, the scientists from the Institute of Physical Materials Science of the Siberian Branch of the Russian Academy of Sciences under the supervision of Alexander Bazarov are planning to create a network of ASMCs in the Republic of Buryatia to monitor, assess and forecast forest fire danger.

The research work within the project of the Russian Foundation for Basic Research No. 20-31-51001 on analysis of the influence of human impact from main railway lines on forest fire danger is ongoing as well.

The scientists tell about the results of these projects in the series of podcasts on Yandex Music, a music streaming service.

Scientists of Tomsk Polytechnic University were able to obtain polytetrafluoroethylene (PTFE) membranes using electrospinning. PTFE is known to be the most stable existent polymer.

According to the scientists, it is a simple, affordable and easily scalable method, which will allow obtaining chemically stable membranes in industrial-scale production. The membranes can be used in petrochemical, aerospace, nuclear industries, carbon-free energy and medicine.

The latest results of the research of physical and chemical properties and biocompatibility of the obtained membranes are published in the Journal of Fluorine Chemistry (IF: 2,332; Q1). The obtained membranes were tested using cells and laboratory animals. The research confirmed that the membranes are not rejected by the cells and are not destroyed in the biological matrix. The interdisciplinary team consisting of physicists and chemicals is currently conducting the research at TPU.

“The material and methods of work with it were noteworthy for us. PTFE is a polymer containing fluorine. Fluorine and similar compounds are called fluoropolymers. They are noteworthy for scientists and experts working at industrial enterprises due to their inert. Fluoropolymers can be used in corrosive media or where material stability is crucial. These either can be hydrogen fuel cells operating in the conditions of corrosive media or a medical implant inside a human body. It means that obtaining membranes is very perspective, however, there is no large capacity technology in the world yet. It is either expensive or labour-intensive, even if the raw material is affordable,” Evgeny Bolbasov, Research Fellow of the TPU Butakov Research Center, says.

The TPU scientists used electrospinning. It is drawing charged threads of polymer solutions under the effect of an electric field. The result is a knitted material of polymer threads.

“The main advantage of the method is that the small laboratory installation is not different from an industrial one by its core and processes. Everything that can be done in the laboratory is easily reproducible at the enterprise. Previously, it was believed that obtaining a PTFE membrane using electrospinning is simply impossible. PTFE is not pulled into threads. To solve this problem, we added polyvinyl alcohol (PVA), a crosslinking agent in the synthesis chain,” the scientist says.

The process of obtaining the membrane described in the article carries two stages. First, very fine powder is mixed with PVA. A solution loading in the electrospinning installation is obtained. The thinnest threads are pulled inside of the electrospinning installation and the white porous bed is spun from these pulled threads. It is the membrane. At stage two, the membrane is fired in an oven at about 400°С. The added PVA completely evaporates in the oven and the membrane is getting dark a bit. The entire process takes no longer than three hours.

The researchers note that all raw materials used for the synthesis are commercially affordable and are produced in Russia.

These membranes possess a wide range of potential applications. Only a scalable technology is required. Industrial methods of obtaining membranes from fluoropolymers are searched in Europe, the USA, China. Meanwhile, the Russian scientists possess an opportunity to offer a commercially interesting solution. From our point of view, electrospinning is such a solution.

This method is a dozen folds cheaper than its alternatives, it allows easily controlling the pore structure of the membranes. Moreover, this method is reproducible and scalable, which is very interesting for potential industrial partners,” Vyacheslav Buznik, an academician of the Russian Academy of Sciences, one of the article authors, says.

“Currently, the main task of the TPU researchers is to show the method opportunities for solving specific applied problems. The task is complicated, complex. It can be solved only by interdisciplinary teams consisting of materials specialists, chemists, physicists. It is crucially important for us that there are all the required experts and competencies at TPU. It will help us to actively develop this field,” Marina Trusova, Director of the TPU Research School of Chemistry and Applied Biomedical Sciences, notes.

Scientists of Tomsk Polytechnic University jointly with colleagues from Spanish universities have offered a simple method how to enhance the responsivity of terahertz radiation detectors by 3.5 folds using a small Teflon cube.  The 1 mm cube must be put on the surface of the detector without changing the inner design of the detector.

Such detectors are applied, for instance, in a full-body scanner, spectrometer, in medical devices for diagnosing skin cancer, burn injuries, pathological changes in the blood.  The research findings are published in the Optics Letter academic journal (IF: 3,714; Q1).

Terahertz range lies between microwave and infrared ranges in the electromagnetic spectrum. Waves shorter than 1 mm refer to the terahertz range. Their feature lies in that they are capable to percolate various materials and at the same time, they do not lead to atomic ionization of matter alternatively to X-rays.

“Terahertz radiation detectors are, as a rule, rather compact devices.  Nowadays, researchers from different countries are interested in the enhancement of their responsivity and other parameters.  The higher responsivity, the weaker signals can be received and more precise measurements can be carried out,” Oleg Minin, Professor of the Division for Electronic Engineering of the TPU School of Non-Destructive Testing, one of the authors of the article, says.

“Most researchers are trying to solve this problem by changing the design of the detector and the materials it is made from. It is complicated and often very expensive. Meanwhile, our solution is plain to see.”

In their experiments, the scientists used a microparticle in the form of the Teflon cube, an available dielectric material through which electromagnetic waves of the terahertz range are capable to percolate.  The cube was put on the surface of the detector.

“There is a responsive site inside of the detector.  The site can be made from various materials but its typical scale is always less than the wavelength.  It is the area responsible for trapping electromagnetic waves and transferring them. Due to the form and material, our cube possesses a capability to focalize radiation well, falling on the responsive site of the detector, in the scale limited to or smaller than a diffraction-limited system. The experiments conducted jointly with the Spanish colleagues proved it: the particle focalized the radiation and the emitted radiation fell into the responsive area,” Oleg Minin explains.

According to the scientists, the developed method of detector responsivity enhancement without changing its design is applied to almost any detectors of various ranges.

During the experiments, the scientists fixed responsivity enhancement by 11 decibels, which is 3.5 folds higher than the standard parameters of the detector.

The researchers from the University of Salamanca (Spain), Polytechnic University of Valencia (Spain), Institute of High-Pressure Physics of the Polish Academy of Sciences (Poland) and Imperial College London (England) took part in the research. The research was conducted with the support of the TPU Competitiveness Enhancement Program.