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Mechanisms of generating electric and magnetic fields during propagation of microsecond CO2-laser pulses in the atmosphere along long paths are considered. The wavelength range of radiation selected for our research is substantiated. The powers of the source required for realization of pre-breakdown and breakdown modes of radiation interaction with the medium are estimated. A dependence of the observed signals on the conditions of radiation propagation is investigated. Theoretical estimates and results of field experiments are compared.

Results are presented of the experimental study of electric and magnetic fields generated during pulsed laser radiation propagation along atmospheric paths in breakdown and prebreakdown modes. Generation of quasi-periodic electric and magnetic fields with a frequency of 105–106 Hz and duration of 10–100 μs during propagation of microsecond CO2 laser pulses through the atmosphere in these modes is ascertained. The maximum values of the induced electric and magnetic fields are observed when the number of breakdown centers per unit path length Nc = 0.17 m−1. The connection of electric and magnetic fields generated around the ionization channel with the atmospheric parameters is shown.

We report on the synthesis of the epoxy-based composites with graphene fillers and test their electromagnetic shielding efficiency by the quasi-optic free-space method in the extremely high-frequency (EHF) band (220-325 GHz). The curing adhesive composites were produced by a scalable technique with a mixture of single-layer and few-layer graphene layers of few-micrometer lateral dimensions. It was found that the electromagnetic transmission, T, is low even at small concentrations of graphene fillers: T

The paper deals with the propagation of the powerful laser beam in gas-dispersion systems and atmospheric aerosol background, which is accompanied by a wide spectrum of thermal, acoustic-and-hydrodynamic and ionization processes arising both in the vicinity of particles and at the beam level. The analysis is performed for the main interaction mechanisms of the high-energy laser beam and gas-dispersion systems, including those containing metals. A state-transition diagram is constructed to evaluate physical processes observed in the laser channel propagation.

We report on the investigation of thermal transport in noncured silicone composites with graphene fillers of different lateral dimensions. Graphene fillers are comprised of few-layer graphene flakes with lateral sizes in the range from 400 to 1200 nm and the number of atomic planes from 1 to μ100. The distribution of the lateral dimensions and thicknesses of graphene fillers has been determined via atomic force microscopy statistics. It was found that in the examined range of the lateral dimensions, the thermal conductivity of the composites increases with increasing size of the graphene fillers. The observed difference in thermal properties can be related to the average gray phonon mean free path in graphene, which has been estimated to be around μ800 nm at room temperature. The thermal contact resistance of composites with graphene fillers of 1200 nm lateral dimensions was also smaller than that of composites with graphene fillers of 400 nm lateral dimensions. The effects of the filler loading fraction and the filler size on the thermal conductivity of the composites were rationalized within the Kanari model. The obtained results are important for the optimization of graphene fillers for applications in thermal interface materials for heat removal from high-power-density electronics.

The procedure of measurement of the brightness distribution of the hard X-ray source of the MIB-7.5 betatron with a penumbral aperture is detailed (i.e., a measurement algorithm and a calculation model are proposed). This measurement method involves reconstructing the brightness distribution of a source based on the radiation distribution in the penumbral region of a large circular collimator. The influence of the penumbral aperture diameter on the signal-to-noise ratio in the distribution of the source brightness is estimated. A parametric model of formation of the source X-ray pattern is presented. This model is based on a priori information on the measurement setting and the brightness distribution of the radiation source.

Results of measurements of the conductivity and electric field strength in the laser radiation propagation channel and near it are presented. An experimental setup and measurement scheme are described. The data have been obtained in the prebreakdown regime. The dependences of the laser-induced field strength on the laser radiation power and the optical characteristics of the propagation channel are investigated. The feasibility of ionization channel diagnostics using the electro-optical effects in the atmosphere is shown.

We report on experimental investigation of thermal contact resistance, RC, of the noncuring graphene thermal interface materials with the surfaces characterized by different degree of roughness, Sq. It is found that the thermal contact resistance depends on the graphene loading, ξ, non-monotonically, achieving its minimum at the loading fraction of ξ ~15 wt%. Decreasing the surface roughness by Sq~1 μm results in approximately the factor of ×2 decrease in the thermal contact resistance for this graphene loading. The obtained dependences of the thermal conductivity, KTIM, thermal contact resistance, RC, and the total thermal resistance of the thermal interface material layer on ξ and Sq can be utilized for optimization of the loading fraction of graphene for specific materials and roughness of the connecting surfaces. Our results are important for the thermal management of high-power-density electronics implemented with diamond and other wide-band-gap semiconductors.

The localized release of energy at the surface of plasma-exposed materials plays a crucial role in many plasma-driven processes. Unfortunately, the interaction between low-temperature plasmas and surfaces is both poorly understood and difficult to characterize. Here, we use Raman thermometry to measure the temperature of graphene during plasma exposure. We observe a significant increase in the graphene temperature even for modest input plasma powers. These results suggest that two-dimensional materials are effective surface probes for the quantitative characterization of plasma-induced heating effects and for further investigation of the plasma-surface interaction.

We review the current state-of-the-art graphene-enhanced thermal interface materials for the management of heat in the next generation of electronics. Increased integration densities, speed and power of electronic and optoelectronic devices require thermal interface materials with substantially higher thermal conductivity, improved reliability, and lower cost. Graphene has emerged as a promising filler material that can meet the demands of future high-speed and high-powered electronics. This review describes the use of graphene as a filler in curing and non-curing polymer matrices. Special attention is given to strategies for achieving the thermal percolation threshold with its corresponding characteristic increase in the overall thermal conductivity. Many applications require high thermal conductivity of composites, while simultaneously preserving electrical insulation. A hybrid filler approach, using graphene and boron nitride, is presented as a possible technology providing for the independent control of electrical and thermal conduction. The reliability and lifespan performance of thermal interface materials is an important consideration towards the determination of appropriate practical applications. The present review addresses these issues in detail, demonstrating the promise of graphene-enhanced thermal interface materials compared to alternative technologies.

Investigating impact interaction of solid and deformed bodies with obstacles of various physical natures requires developing experimental methodologies of registering the parameters of the interaction process. In experimental investigations of impact interaction of solids, it is common practice to measure displacement of strikers as a function of time, as well as their velocity and deceleration. To determine the displacement and velocity of a striker, a radio-interferometric methodology of registering the displacement of its rear end is proposed. In contrast with the registration methods based on high-speed filming and pulsed X-ray photography, the method using a millimeter-range radio-interferometer provides continuous high-accuracy registering of the displacement of the rear end of a striker in a wide range of displacement values. To test the effectiveness of the methodology, a series of experiments have been conducted on registering the motion of a cylindrical striker of an aluminum alloy, fired from a 20mm-dia gas gun. The displacement of the striker was also monitored using high-speed filming. The results of measuring using the two methodologies differ within the limits of the error of measurement. Based on the results of the above experiments, it has been concluded that the methodology of determining the displacement and velocity of strikers in a ballistic experiment using a mm-range radio-interferometer makes it possible to measure practically continuously large displacements (100 mm and larger) to a safe accuracy. The present methodology can be used for measuring the displacement and velocity of the rear end of a striker interacting with obstacles of various physical natures (metals, ceramics, soils, concretes, etc.).

Proton radiation damage is an important failure mechanism for electronic devices in near-Earth orbits, deep space and high energy physics facilities. Protons can cause ionizing damage and atomic displacements, resulting in device degradation and malfunction. Shielding of electronics increases the weight and cost of the systems but does not eliminate destructive single events produced by energetic protons. Modern electronics based on semiconductors - even those specially designed for radiation hardness - remain highly susceptible to proton damage. Here we demonstrate that room temperature (RT) charge-density-wave (CDW) devices with quasi-two-dimensional (2D) 1T-TaS2 channels show remarkable immunity to bombardment with 1.8 MeV protons to a fluence of at least 10^14 H+cm^2. Current-voltage I-V characteristics of these 2D CDW devices do not change as a result of proton irradiation, in striking contrast to most conventional semiconductor devices or other 2D devices. Only negligible changes are found in the low-frequency noise spectra. The radiation immunity of these "all-metallic" CDW devices can be attributed to their two-terminal design, quasi-2D nature of the active channel, and high concentration of charge carriers in the utilized CDW phases. Such devices, capable of operating over a wide temperature range, can constitute a crucial segment of future electronics for space, particle accelerator and other radiation environments., 18 pages, 2 display items

In this Perspective, I present a concise account concerning the emergence of the research field investigating the phononic and thermal properties of graphene and related materials, covering the refinement of our understanding of phonon transport in two-dimensional material systems. The initial interest in graphene originated from its unique linear energy dispersion for electrons, revealed in exceptionally high electron mobility, and other exotic electronic and optical properties. Electrons are not the only elemental excitations influenced by a reduction in dimensionality. Phonons-quanta of crystal lattice vibrations-also demonstrate an extreme sensitivity to the number of atomic planes in the few-layer graphene, resulting in unusual heat conduction properties. I outline recent theoretical and experimental developments in the field and discuss how the prospects for the mainstream electronic application of graphene, enabled by its high electron mobility, gradually gave way to emerging real-life products based on few-layer graphene, which utilize its unique heat conduction rather than its electrical conduction properties.

We report on the lifespan evolution of thermal diffusivity and thermal conductivity in curing epoxy-based thermal interface materials with graphene fillers. The performance and reliability of graphene composites have been investigated in up to 500 power cycling measurements. The tested composites were prepared with an epoxy resin base and randomly oriented fillers consisting of a mixture of few-layer and single-layer graphene. The power cycling treatment procedure was conducted with a custom-built setup, while the thermal characteristics were determined using the &ldquo, laser flash&rdquo, method. The thermal conductivity and thermal diffusivity of these composites do not degrade but instead improve with power cycling. Among all tested filled samples with different graphene loading fractions, an enhancement in the thermal conductivity values of 15% to 25% has been observed. The obtained results suggest that epoxy-based thermal interface materials with graphene fillers undergo an interesting and little-studied intrinsic performance enhancement, which can have important implications for the development of next-generation thermal interface materials.

The problem of the optimal stabilization of a vertical rigid rotor rotating in two electromagnetic bearings is considered. A quantitative estimate of transient processes is based on the maximal deviation of the rotor from the equilibrium state and the maximal value of the current intensity in the windings of electromagnets. The use of linear matrix inequalities allow synthesizing the Pareto optimal control laws in the form of linear state-feedback, as well as decentralized control laws, which are defined by the displacements of the rotor in each electromagnetic bearing. The Pareto optimal criteria for centralized and decentralized control laws are compared. It is shown that utilization of simple easily realizable decentralized control laws only slightly worsens transient processes.

We investigated thermal properties of the epoxy-based composites with the high loading fraction-up to f ≈ 45 vol %-of the randomly oriented electrically conductive graphene fillers and electrically insulating boron nitride fillers. It was found that both types of the composites revealed a distinctive thermal percolation threshold at the loading fraction fT > 20 vol %. The graphene loading required for achieving thermal percolation, fT, was substantially higher than the loading, fE, for electrical percolation. Graphene fillers outperformed boron nitride fillers in the thermal conductivity enhancement. It was established that thermal transport in composites with high filler loadings, f ≥ fT, is dominated by heat conduction via the network of percolating fillers. Unexpectedly, we determined that the thermal transport properties of the high loading composites were influenced strongly by the cross-plane thermal conductivity of the quasi-two-dimensional fillers. The obtained results shed light on the debated mechanism of the thermal percolation, and facilitate the development of the next generation of the efficient thermal interface materials for electronic applications.

We propose logic gates and circuits implemented with 2-D charge density wave (CDW) devices, which operate at room temperature. The 1T-TaS2 charge density wave devices exhibit a voltage triggered phase transition between the nearly commensurate and incommensurate CDW states, which is accompanied by an abrupt change of the resistance and hysteresis. The unique output characteristics of such devices allow for building logic gates and circuits without any transistors. Using the experimentally measured current–voltage characteristics, we model and numerically simulate the performance of the inverter and the OR logic gates consisting of CDW devices and regular resistors. Owing to the radiation-hard nature of the CDW devices and absence of transistors, the proposed circuits can be utilized in various harsh environments on earth or outer space.

Works are analyzed from which the possibility follows of ionization of the atmosphere upon exposure to laser radiation to develop laser antennas and systems of protection from lightning. Various effects leading to increased ionization of air in the pre-breakdown regime are considered, including photo- and thermal ionization, electroionization, surface ionization, chemical reactions, etc. together with the main ionization mechanism – laser breakdown of the atmosphere. The laser radiation parameters necessary for realization of the ionization channel in the atmosphere are estimated.

Thermal management remains one of the major challenges in the design of safe and reliable Li-ion batteries. We show that composite electrodes assembled from commercially available 100 μm long carbon nanotubes (CNTs) and LiCoO2 (LCO) particles demonstrate the in-plane thermal conductivity of 205.8 W/m*K. This value exceeds the thermal conductivity of dry conventional laminated electrodes by about three orders of magnitude. The cross-plane thermal conductivity of CNT-based electrodes is in the same range as thermal conductivities of conventional laminated electrodes. The CNT-based electrodes demonstrate a similar capacity to conventional laminated design electrodes, but revealed a better rate performance and stability. The introduction of diamond particles into CNT-based electrodes further improves the rate performance. Our lightweight, flexible electrode design can potentially be a general platform for fabricating polymer binder- and aluminum and copper current collector-free electrodes from a broad range of electrochemically active materials with efficient thermal management.

The Raman spectra of large-size, single-crystal, twisted bilayer graphene (tBLG) grains grown by chemical vapor deposition (CVD) are measured as a function of the rotation angle. The rotation angle between the graphene layers is determined using a combination of transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The 2D and G peaks follow the same trends as found previously. The low-frequency peaks (

We describe Raman spectroscopy-based method of measuring thermal conductivity of thin films and review significant results achieved with this technique pertinent to graphene and other two-dimensional materials. The optothermal Raman method was instrumental for the discovery of unique heat conduction properties of graphene. In this method, Raman spectroscopy is used to determine the local temperature of the sample, while the excitation laser is utilized as a heat source. The success of Raman spectroscopy in investigating thermal conductivity of suspended graphene and graphene-based thin films motivated the extension of this technique to other material systems and films. Copyright © 2017 John Wiley & Sons, Ltd.

The optimal stabilization problem is considered for bodies in electromagnetic suspensions. To solve this problem, we form a linear stationary control law for the linearized system. This law is based on the feedback principle and uses the measuring of the current intensity in the circuit of the electromagnet, while the location of the body and its velocity are not measured. The optimality criterion is the generalized H ∞-norm of the linearized system: it characterizes the extinguishing level for perturbations generated by external actions and unknown initial conditions. To compute the feedback parameters, the technique of linear matrix inequalities is applied. We provide mathematical simulation examples for the dynamics of a body in an electromagnetic suspension.

We report the results of an experimental study of thermal and magnetic properties of nanostructured ferrimagnetic iron oxide composites with graphene and graphite fillers synthesized via the current activated pressure assisted densification. The thermal conductivity was measured using the laser-flash and transient plane source techniques. It was demonstrated that addition of 5 wt.% of equal mixture of graphene and graphite flakes to the composite results in a factor of ×2.6 enhancement of the thermal conductivity without significant degradation of the saturation magnetization. The microscopy and spectroscopic characterization reveal that sp2 carbon fillers preserve their crystal structure and morphology during the composite processing. The strong increase in the thermal conductivity was attributed to the excellent phonon heat conduction properties of graphene and graphite. The results are important for energy and electronic applications of the nanostructured permanent magnets. Keywords: Permanent magnets, Graphene, Thermal conductivity, Thermal management

Almost 15 years have gone ever since the discovery of graphene as a single atom layer. Numerous papers have been published to demonstrate its high electron mobility, excellent thermal and mechanical as well as optical properties. We have recently seen more and more applications towards using graphene in commercial products. This paper is an attempt to review and summarize the current status of the research of the thermal properties of graphene and other 2D based materials including the manufacturing and characterization techniques and their applications, especially in electronics and power modules. It is obvious from the review that graphene has penetrated the market and gets more and more applications in commercial electronics thermal management context. In the paper, we also made a critical analysis of how mature the manufacturing processes are; what are the accuracies and challenges with the various characterization techniques and what are the remaining questions and issues left before we see further more applications in this exciting and fascinating field., YF, JH, YL, AZ, MK and JL acknowledge the financial support from The Swedish National Science Foundation (VR under the contract No 621-2007-4660), The Swedish Foundation for Strategic Research (SSF) under contract (No SE13-0061), the Swedish Board for innovation under the Siografen program and from the Production Area of Advance at Chalmers University of Technology, Sweden. SC, YZ and JL acknowledge the financial support by the Key R&D Development Program from the Ministry of Science and Technology of China with the contract No: 2017YFB040600 and the National Natural Science Foundation of China (No. 51872182). XX is supported the National Natural Science Foundation of China (No. 11674245 & No. 11890703). MS and CMST acknowledge financial support from the CERCA programme/Generalitat de Catalunya, the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, Grant No. SEV-2017-0706).

Nature photonics 14(6), 391 - 397 (2020). doi:10.1038/s41566-020-0607-z, The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created., Published by Nature Publ. Group, London [u.a.]

Temperature rise in multi-junction solar cells reduces their efficiency and shortens their lifetime. We report the results of the feasibility study of passive thermal management of concentrated multi-junction solar cells with the non-curing graphene-enhanced thermal interface materials. Using an inexpensive, scalable technique, graphene and few-layer graphene fillers were incorporated in the non-curing mineral oil matrix, with the filler concentration of up to 40 wt% and applied as the thermal interface material between the solar cell and the heat sink. The performance parameters of the solar cells were tested using an industry-standard solar simulator with concentrated light illumination at 70&times, and 200&times, suns. It was found that the non-curing graphene-enhanced thermal interface material substantially reduces the temperature rise in the solar cell and improves its open-circuit voltage. The decrease in the maximum temperature rise enhances the solar cell performance compared to that with the commercial non-cured thermal interface material. The obtained results are important for the development of the thermal management technologies for the next generation of photovoltaic solar cells.

The article deals with studying the power supply system. At present the problem of saving energy is particularly acute. It is solved by means of reducing consumption (introducing modern energy-saving technologies) and reducing energy losses. One of the components of the electrical power loss is the presence of reactive power in the enterprise network. Reactive power is generated by electrical equipment with inductive resistance. The presence of reactive power has a negative impact on the electrical network of an industrial enterprise, namely, the networks capacity is reduced, and the load on power transformers increases. The authors propose an integrated approach to introducing compensation devices to reduce losses, provide a calculation of the compensation sets power depending on the active load of the enterprise and depending on the power factor.

A macroscopic film (2.5 cm × 2.5 cm) made by layer-by-layer assembly of 100 single-layer polycrystalline graphene films is reported. The graphene layers are transferred and stacked one by one using a wet process that leads to layer defects and interstitial contamination. Heat-treatment of the sample up to 2800 °C results in the removal of interstitial contaminants and the healing of graphene layer defects. The resulting stacked graphene sample is a freestanding film with near-perfect in-plane crystallinity but a mixed stacking order through the thickness, which separates it from all existing carbon materials. Macroscale tensile tests yields maximum values of 62 GPa for the Young's modulus and 0.70 GPa for the fracture strength, significantly higher than has been reported for any other macroscale carbon films; microscale tensile tests yield maximum values of 290 GPa for the Young's modulus and 5.8 GPa for the fracture strength. The measured in-plane thermal conductivity is exceptionally high, 2292 ± 159 W m-1 K-1 while in-plane electrical conductivity is 2.2 × 105 S m-1 . The high performance of these films is attributed to the combination of the high in-plane crystalline order and unique stacking configuration through the thickness.

We report on heat conduction properties of thermal interface materials with self-aligning "magnetic grapheme" fillers. Graphene enhanced nano-composites were synthesized by an inexpensive and scalable technique based on liquid-phase exfoliation. Functionalization of graphene and few-layer-graphene flakes with Fe3O4 nanoparticles allowed us to align the fillers in an external magnetic field during dispersion of the thermal paste to the connecting surfaces. The filler alignment results in a strong increase of the apparent thermal conductivity and thermal diffusivity through the layer of nano-composite inserted between two metallic surfaces. The self-aligning "magnetic grapheme" fillers improve heat conduction in composites with both curing and non-curing matrix materials. The thermal conductivity enhancement with the oriented fillers is a factor of two larger than that with the random fillers even at the low ~1 wt. % of graphene loading. The real-life testing with computer chips demonstrated the temperature rise decrease by as much as 10oC with use of the non-curing thermal interface material with ~1 wt. % of the oriented fillers. Our proof-of-concept experiments suggest that the thermal interface materials with functionalized graphene and few-layer-graphene fillers, which can be oriented during the composite application to the surfaces, can lead to a new method of thermal management of advanced electronics., 34 pages; 8 figures

This study aimed to assess the efficacy of ceftolozane-tazobactam (C/T) for treating infections due to Pseudomonas aeruginosa (P. aeruginosa) in critically ill patients.A multicenter, retrospective and observational study was conducted in critically ill patients receiving different C/T dosages and antibiotic combinations for P. aeruginosa infections. Demographic data, localisation and severity of infection, clinical and microbiological outcome, and mortality were evaluated.Ninety-five patients received C/T for P. aeruginosa serious infections. The main infections were nosocomial pneumonia (56.2%), intra-abdominal infection (10.5%), tracheobronchitis (8.4%), and urinary tract infection (6.3%). Most infections were complicated with sepsis (49.5%) or septic shock (45.3%), and bacteraemia (10.5%). Forty-six episodes were treated with high-dose C/T (3 g every 8 hours) and 38 episodes were treated with standard dosage (1.5 g every 8 hours). Almost half (44.2%) of the patients were treated with C/T monotherapy, and the remaining group received combination therapy with other antibiotics. Sixty-eight (71.6%) patients presented a favourable clinical response. Microbiological eradication was documented in 42.1% (40/95) of the episodes. The global ICU mortality was 36.5%. Univariate analysis showed that 30-day mortality was significantly associated (P0.05) with Charlson Index at ICU admission and the need of life-supporting therapies.C/T appeared to be an effective therapy for severe infections due to P. aeruginosa in critically ill patients. Mortality was mainly related to the severity of the infection. No benefit was observed with high-dose C/T or combination therapy with other antibiotics.

We report results of investigation of the low-frequency electronic excess noise in quasi-1D nanowires of TaSe3 capped with quasi-2D h-BN layers. Semimetallic TaSe3 is a quasi-1D van der Waals material with exceptionally high breakdown current density. It was found that TaSe3 nanowires have lower levels of the normalized noise spectral density, SI/I2, compared to carbon nanotubes and graphene (I is the current). The temperature-dependent measurements revealed that the low-frequency electronic 1/f noise becomes the 1/f2 type as temperature increases to ∼400 K, suggesting the onset of electromigration (f is the frequency). Using the Dutta–Horn random fluctuation model of the electronic noise in metals, we determined that the noise activation energy for quasi-1D TaSe3 nanowires is approximately EP ≈ 1.0 eV. In the framework of the empirical noise model for metallic interconnects, the extracted activation energy, related to electromigration is EA = 0.88 eV, consistent with that for Cu and Al interconnects. Our...

The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the process can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. In addition, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics., Direct growth of large-area graphene on dielectric substrates is a promising route to wafer scale integration. Here the authors use a rapid thermal annealing process to grow graphene layers on four-inch diameter polycrystalline diamond, eliminating the need for transfer.

We demonstrate experimentally the operation of a spin-wave magnetometer integrated into a circuit with a positive feedback. The circuit consists of the passive magnetic and active electric parts. The magnetic part includes a sensing element, which is a magnetic cross junction made of Y3Fe2(FeO4)3. The electric part includes a non-linear amplifier and a phase shifter. The electric and magnetic parts are connected via micrometer size antennae. Spin waves are excited by two of these antennae while the output inductive voltage produced by the interfering spin waves is detected by the third antenna. Spin waves propagating in the orthogonal arms of the cross can accumulate significantly different phase shifts, depending on the direction and the strength of the external magnetic field. The output inductive voltage reaches its maximum in the case of constructive spin wave interference. The positive feedback provides further signal amplification. It appears possible to enhance the response function, compared to the passive circuits without a feedback, by a factor of ×100 without an increase in the noise level. The experimental data show a prominent response to the external magnetic field variation, exceeding 5 × 10 3 V / T . The intrinsic noise spectral density of the device can be as low as 10-16 V2/Hz. The estimated sensitivity of the prototype device is 2 × 10 - 12 T / √ H z at room temperature. We argue that spin-wave magnetometers can potentially be as sensitive as SQUIDs while operating at room temperature.

The work presents experimental and numerical results on dynamic fracture of PMMA plates subjected to impact loading. The experimental tests were conducted using steel cylinder-shaped projectile accelerated using a gas gun. In order to evaluate performance of the tested specimens, residual impactor velocity was assessed using high-speed photography setup. Square-shaped PMMA specimens with three thicknesses were investigated using various projectile velocities. For all the three specimen types the ballistic limits were experimentally obtained. The conducted experiments were numerically simulated using finite element method with explicit time integration scheme and incubation time fracture model for the material failure prediction. Experiments with all three specimen configurations were successfully simulated using one parameter – incubation time, which was evaluated from existing experimental data on the dynamic fracture of PMMA. In addition to the simulations of the real experiments estimates on performance of a sample with a virtual geometry were made using the developed numerical approach.

Avicin A is a bacteriocin from the gram-positive bacterium Enterococcus avium. It exhibits a high microbicidal activity against bacteria of the genus Listeria, a causative agent of the severe human infection listeriosis. We developed a biotechnological method for obtaining avicin A and characterized its structure and biological activity. We also proposed a possible mechanism of the antimicrobial action of avicin A.

A novel multi-objective robust control problem is studied for systems with structured norm-bounded uncertainty and robust generalized H 2 norms as criteria. Necessary conditions for Pareto optimality are formulated. Pareto optimal solutions turn out to be among optimal solutions for multiobjective costs in the form of Germeyer convolution. Pareto suboptimal controllers are defined as the optimal solutions for the upper bounds of the multi-objective costs and characterized in terms of LMIs. The upper and lower bounds of the multi-objective cost are used to compute a suboptimality measure which allows to estimate a “difference” between Pareto suboptimal and unavailable Pareto optimal controllers. Two-criteria robust control problem for a mathematical model of the rotor rotating in active magnetic bearings is considered as an application of this theory.

A novel optimal control problems with multiple criteria are considered for the mathematical model of the rotating rotor in active magnetic bearings. The methods for searching Pareto optimal solutions are based on feedback linearization, Germeyer scalarization, convex optimization, and linear matrix inequalities technique. Analytical and numerical solutions for decentralized and centralized controllers are given.

We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ∼7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 10(10) cm(-2) to 1.8 × 10(11) cm(-2) the thermal conductivity decreases from ∼(1.8 ± 0.2) × 10(3) W mK(-1) to ∼(4.0 ± 0.2) × 10(2) W mK(-1) near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ∼400 W mK(-1). The thermal conductivity dependence on the defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management.

The recombinant isoforms Lc-LTP1 and Lc-LTP3 of the lentil lipid transfer protein were overexpressed in E. coli cells. It was confirmed that both proteins are stabilized by four disulfide bonds and characterized by a high proportion of the -helical structure. It was found that Lc-LTP1 and Lc-LTP3 possess antimicrobial activity and can bind fatty acids. Both isoforms have the ability to bind specific IgE from sera of patients with food allergies, which recognize similar epitopes of the major peach allergen Pru p 3. Both isoforms were shown to have immunological properties similar to those of other plant allergenic LTPs, but Lc-LTP3 displayed a less pronounced immunoreactivity.

Thermal conductivity of free-standing reduced graphene oxide films subjected to a high-temperature treatment of up to 1000 °C is investigated. It is found that the high-temperature annealing dramatically increases the in-plane thermal conductivity, K, of the films from ≈3 to ≈61 W m−1 K−1 at room temperature. The cross-plane thermal conductivity, K⊥, reveals an interesting opposite trend of decreasing to a very small value of ≈0.09 W m−1 K−1 in the reduced graphene oxide films annealed at 1000 °C. The obtained films demonstrate an exceptionally strong anisotropy of the thermal conductivity, K/K⊥ ≈ 675, which is substantially larger even than in the high-quality graphite. The electrical resistivity of the annealed films reduces to 1–19 Ω □−1. The observed modifications of the in-plane and cross-plane thermal conductivity components resulting in an unusual K/K⊥ anisotropy are explained theoretically. The theoretical analysis suggests that K can reach as high as ≈500 W m−1 K−1 with the increase in the sp2 domain size and further reduction of the oxygen content. The strongly anisotropic heat conduction properties of these films can be useful for applications in thermal management.

Graphene revealed a number of unique properties beneficial for electronics, including exceptionally high electron mobility and widely tunable Fermi level. However, graphene does not have an electron energy band gap, which presents a serious hurdle for its applications in digital electronics. A possible route for practical use of graphene in electronics is utilization of its exceptionally high thermal conductivity and electron current conducting properties. This invited review outlines the thermal properties of graphene and describes prospective graphene technologies that are not affected by the absence of the energy band gap. The specific examples include heat spreaders, thermal coatings, high-current density electrodes and interconnects. Our results suggest that the thermal management of advanced electronic devices can become the first industry scale application of graphene.

Development of the next generation of micro- and nanoscale electronics requires efficient thermal management. As the dissipated power density increases, heat removal becomes a critical issue. This motivates researchers to investigate and synthesize materials that can drastically improve thermal management of electronic devices. The discovery of the exceptionally high thermal conductivity of graphene has led to significant progress in thermally conductive coatings and thermal interface materials. In this chapter, we review recent progress in graphene applications for thermal management, focusing on graphene laminates, reduced graphene oxide films, and graphene fillers in composite materials.

The possibility of stabilizing the unstable transverse motion of a rotor spinning in a housing by changing the hydrodynamic forces acting on the rotor from the gas filling the housing is investigated. The desired change in the forces is found to be possible by using special correctors arranged on the internal cylindrical surface of the housing. The stability conditions of the transverse motion of the rotor are obtained. An example of a corrector that ensures stable motion is presented.

The authors review thermal properties of graphene and few-layer graphene (FLG), and discuss applications of these materials in thermal management of advanced electronics. The intrinsic thermal conductivity of graphene - among the highest of known materials - is dominated by phonons near the room temperature. The examples of thermal management applications include the FLG heat spreaders integrated near the heat generating areas of the high-power density transistors. It has been demonstrated that FLG heat spreaders can lower the hot-spot temperature during device operation, resulting in improved performance and reliability of the devices.

This chapter discusses thermoelectric properties of individual quintuples and stacks of the graphene-like exfoliated single-crystal quasi-two-dimensional Bi2Te3 films. It shows that ZT in such “pseudo-superlattices” of the stacked films can be substantially increased via reduction of the in-plane and cross-plane thermal conductivity with simultaneously preserved good electrical properties in the films with smooth interfaces. The improvement of thermoelectric properties via phonon engineering also can be achieved in thin films or nanowires with the thickness of just few atomic layers and high quality of interfaces. The epitaxially grown films have to be lattice matched to the substrate, which leads to a small acoustic impedance mismatch and, as a result, the absence of strong confinement effects for the acoustic phonons. The exfoliated atomically thin films have nearly infinite confining potential barriers for both electrons as holes as well as for acoustic phonons, which carry the heat.

Genes encoding two three-finger toxins TFT-AF and TFT-VN, nucleotide sequences of which were earlier determined by cloning cDNA from venom glands of vipers Azemiops feae and Vipera nikolskii, respectively, were expressed for the first time in E. coli cells. The biological activity of these toxins was studied by electrophysiological techniques, calcium imaging, and radioligand analysis. It was shown for the first time that viper three-finger toxins are antagonists of nicotinic acetylcholine receptors of neuronal and muscle type.

The noise mechanisms in graphene and MoS 2 are quite different. The noise characteristics of MoS 2 transistors could be described by the McWhorter model. The range of the trap densities responsible for the 1/f noise in MoS 2 extracted from the noise measurements is from ∼1018 eV−1cm−3 to ∼ 6×1020 eV−1cm−3. The smallest noise level and smallest trap density was found for multilayer MoS 2 transistors with the number of layer N>6. The noise level in graphene, in general, is much smaller than in MoS 2 transistors and does not comply with the McWhorter model. The low frequency noise in high quality graphene transistors might be relatively low and comparable to Si MOSFETs. The contacts have an important effect on the noise in graphene, but the dominant sources of noise in not aged devices is the channel. The gate voltage dependencies of noise in graphene indicate that the mobility fluctuations give the dominant contribution to noise. The noise measurements of electron irradiated graphene devices and measurements in magnetic field confirm this hypothesis. Both in MoS 2 and graphene, the noise decreases with the number, N, of the atomic layers. The 1/f noise in relatively thin graphene devices with N