Search

The key components of photonic integrated circuits are nanoscale optica emitters and nanowaveguides. III‐V semiconductor nanostructures are considered as the most promising material platform for these components due to highly efficient luminescence and high refractive index, but the problem of emission coupling with waveguide is to be solved. In this work, the use of GaP nanowires (NWs) with different types of doping (GaP:Si or GaP:Be) is proposed as optical waveguides with directly integrated electrically‐driven light sources, solving the problem of emission‐to‐waveguide coupling. Single NWs are integrated with electrodes and pump electroluminescence by a tunnel junction allowing to study emission properties with nanoscale spatial resolution. Basing on the experiments on scanning tunnelling microscopy (STM), electron microscopy, time‐resolved photoluminescence micro‐spectroscopy, X‐ray diffraction, and STM‐induced electroluminescence, it is proven that GaP NWs exhibit different integrated light‐source on doping type of NWs. GaP:Be NWs contain inclusion of the crystalline wurtzite phase with a direct bandgap, and, thus, these NW regions can be considered as electrically‐driven nanoscale sources of light monolithically integrated into GaP NW‐based waveguides. Meanwhile, GaP:Si NWs work as optical waveguides capable of efficient light generation over the entire length of NW. The developed designs are promising for construction of integrated photonic circuits. [ABSTRACT FROM AUTHOR]

Radio frequency identification (RFID) is a widely used wireless technology for contactless data exchange. Owing to international standardization and one-way security nature of the communication protocol, RFID tags, holding sensitive information, may be a subject to theft. One of the major security loopholes is the so-called far-field attack, where unauthorized interrogation is performed from a distance, bypassing the user’s verification. This loophole is a penalty of using a dipole-like RFID tag antenna, leaking wireless information to the far-field. Here we introduce a new concept of anapole-enabled security, prohibiting far-field attacks by utilizing fundamental laws of physics. Our design is based on radiationless electromagnetic states (anapoles), which have high near-field concentration and theoretically nulling far-field scattering. The first property enables performing data readout from several centimeters (near-field), while the second prevents attacks from a distance, regardless an eavesdropper’s radiated power and antenna gain. Our realization is based on a compact 3 cm high-index ceramic core–shell structure, functionalized with a thin metal wire and an integrated circuit to control the tag. Switching scheme was designed to provide a modulation between two radiation-less anapole states, blocking both up and down links for a far-field access. The anapole tag demonstrates more than 20 dB suppression of far-field interrogation distance in respect with a standard commercial tag, while keeping the near-field performance at the same level. The proposed concept might significantly enhance the RFID communication channel in cases, where information security prevails over cost constrains.

We study the effect of structural disorder on the transition from the bound states in the continuum (BICs) to quasi-BICs by the example of the periodic photonic structure composed of two layers of parallel dielectric rods. We uncover the specificity in the robustness of the symmetry-protected and accidental BICs against various types of structural disorder. We analyze how the spatial mode localization induced by the structural disorder results in an effective reduction of the system length and limits the Q factor of quasi-BICs. Our results are essential for the practical implementation of BICs especially in natural and self-assembled photonic structures, where the structural disorder plays a crucial role.

Guided waves are the perfect carriers of electromagnetic signals in planar miniaturized devices due to their high localization and controlled propagation direction. However, it is still a challenge to control the polarization of propagating guided waves. In this work, the broadband polarization TE‐TM degeneracy of highly localized guided waves propagating along an all‐dielectric metasurface and a subwavelength chain of dielectric high‐index cylinders is discovered, both theoretically and experimentally. Using the discovered near‐field polarization degree of freedom, the polarization transformation for guided waves propagating along a subwavelength chain of dielectric cylinders at any frequency within the finite spectral range is demonstrated experimentally. Namely, the simplest planar near‐field polarization device – the quarter‐wave‐retardation (linear‐to‐circular) polarization transformer of guided waves is implemented. The results obtained discover the polarization degree of freedom for guided waves paving the way toward numerous applications in flat optics and planar photonics. [ABSTRACT FROM AUTHOR]

Tumor acidity has been identified as a key factor in promoting cancer progression, metastasis, and resistance. Tumor alkalization therapy has emerged as a potential strategy for cancer treatment. This article provides preclinical and clinical evidence for tumor alkalization therapy as a promising cancer treatment strategy. The potential of tumor alkalization therapy using sodium bicarbonate in the treatment of malignant ascites was studied. The concept of intraperitoneal perfusion with an alkalizing solution to increase the extracellular pH and its antitumor effect were explored. The significant extension in the overall survival of the Ehrlich ascites carcinoma mice treated with sodium bicarbonate solution compared to those treated with a sodium chloride solution was observed. In the sodium bicarbonate group, mice had a median survival of 30 days after tumor cell injection, which was significantly (p<0.05) different from the median survival of 18 days in the sodium chloride group and 14 days in the intact group. We also performed a case study of a patient with ovarian cancer malignant ascites resistant to previous lines of chemotherapy who underwent intraperitoneal perfusions with a sodium bicarbonate solution, resulting in a significant drop of CA-125 levels from 5600 U/mL to 2200 U/mL in and disappearance of ascites, indicating the potential effectiveness of the treatment. The preclinical and clinical results obtained using sodium bicarbonate perfusion in the treatment of malignant ascites represent a small yet significant contribution to the evolving field of tumor alkalization as a cancer therapy. They unequivocally affirm the good prospects of this concept. [ABSTRACT FROM AUTHOR]

Sound absorbing materials capable of working in harsh environments (e.g., fire resistance, moisture resistance, and pressure resistance) while having excellent low-frequency sound absorption properties are highly desirable for many practical applications. Recently, a new class of acoustic absorbers based on space coiling and folding metamaterials (SCFMs) has emerged. The SCFMs could be comprised of rigid plastics, ceramics, and metals and could be a good candidate for developing sound-absorbing devices capable of working in harsh environments. The SCFMs also enable flexible control of low-frequency sound with subwavelength structures, addressing the problem of poor absorption of low-frequency noise encountered by conventional acoustic materials. However, the current geometries of SCFM meta-atoms do not take full advantage of the configuration of three-dimensional space, limiting their ability for flexible control of sound absorption properties. Here, we propose an acoustic absorber based on stacked SCFMs with side openings, which could effectively absorb line-spectrum noise as well as broadband noise. The effects associated with the geometry and resonance modes of SCFMs are shown to significantly influence the sound absorption properties. To understand the sound-metamaterial interaction, an analytical model is obtained to study the acoustic response of SCFMs, which is further validated by numerical simulations. Further experiments have demonstrated the acoustic properties of our proposed metamaterial structure and confirmed the capability of stacked SCFMs for flexible control of the acoustic absorption spectrum. This work provides new possibilities for the development of novel sound absorption metamaterials desirable for many practical applications. [ABSTRACT FROM AUTHOR]

Nonradiating sources of energy have traditionally been studied in quantum mechanics and astrophysics but have received very little attention in the photonics community. This situation has changed recently due to a number of pioneering theoretical studies and remarkable experimental demonstrations of the exotic states of light in dielectric resonant photonic structures and metasurfaces, with the possibility to localize efficiently the electromagnetic fields of high intensities within small volumes of matter. These recent advances underpin novel concepts in nanophotonics and provide a promising pathway to overcome the problem of losses usually associated with metals and plasmonic materials for the efficient control of light-matter interaction at the nanoscale. This review paper provides a general background and several snapshots of the recent results in this young yet prominent research field, focusing on two types of nonradiating states of light that both have been recently at the center of many studies in all-dielectric resonant meta-optics and metasurfaces: optical anapoles and photonic bound states in the continuum. We discuss a brief history of these states in optics, as well as their underlying physics and manifestations, and also emphasize their differences and similarities. We also review some applications of such novel photonic states in both linear and nonlinear optics for the nanoscale field enhancement, a design of novel dielectric structures with high-Q resonances, nonlinear wave mixing, and enhanced harmonic generation, as well as advanced concepts for lasing and optical neural networks.

Acoustic metamaterials and phononic crystals represent a promising platform for the development of noise-insulating systems characterized by a low weight and small thickness. Nevertheless, the operational spectral range of these structures is usually quite narrow, limiting their application as substitutions of conventional noise-insulating systems. In this work, the problem is tackled by demonstration of several ways for the improvement of noise-insulating properties of the periodic structures based on coupled Helmholtz resonators. It is shown that tuning of local coupling between the resonators leads to the formation of a broad stopband covering ∼3.5 octaves (200–2100 Hz) in the transmission spectra. This property is linked to band structures of the equivalent infinitely periodic systems and is discussed in terms of bandgap engineering. The local coupling strength is varied via several means, including introduction of chirped structures and lossy resonators with porous inserts. The stopband engineering procedure is supported by genetic algorithm optimization, and the numerical calculations are verified by experimental measurements. [ABSTRACT FROM AUTHOR]

The relevance of implementing BIM technologies at all stages of the building's life cycle from design to decision-making on its demolition is shown. Variants of the stress-strain state of buildings and structures are considered. An algorithm for analyzing incoming information and making decisions about major repairs, reconstruction, or demolition of an object is developed, depending on the values of parameters, their duration, and combinations obtained from sensors installed during their construction. The use of fiber-optic sensors for obtaining information and subsequent analysis of the state of the building structure and determining dangerous movements of its individual elements is proposed.

The effect of nanosized additives on the strength properties of ceramics based on fusible brick loam of the Klyuchischenskoye deposit has been studied. In general, all nanosized additives selected for the study had a positive effect on the strength properties of ceramics. The greatest increase in strength, when using nanosized silica ash Laksil 30, was 70 %, in relation to the control sample. When using silica ash, an increase in the content of the amorphous phase in the shard after firing is noted against the background of a decrease in its porosity, which causes an increase in strength characteristics. The nature of the destruction of the samples also differed. The destruction of the control sample was accompanied by the formation and gradual opening of cracks. The destruction of the modified samples was more fragile in comparison with the control. Thus, the effectiveness of nanosized additives on the strength properties of ceramics is shown.

Metasurfaces with bound states in the continuum (BICs) have proven to be a powerful platform for drastically enhancing light–matter interactions, improving biosensing, and precisely manipulating near- and far-fields. However, engineering metasurfaces to provide an on-demand spectral and angular position for a BIC remains a prime challenge. A conventional solution involves a fine adjustment of geometrical parameters, requiring multiple time-consuming calculations. In this work, to circumvent such tedious processes, we develop a physics-inspired, inverse design method on all-dielectric metasurfaces for an on-demand spectral and angular position of a BIC. Our suggested method predicts the core–shell particles that constitute the unit cell of the metasurface, while considering practical limitations on geometry and available materials. Our method is based on a smart combination of a semi-analytical solution, for predicting the required dipolar Mie coefficients of the meta-atom, and a machine learning algorithm, for finding a practical design of the meta-atom that provides these Mie coefficients. Although our approach is exemplified in designing a metasurface sustaining a BIC, it can, also, be applied to many more objective functions. With that, we pave the way toward a general framework for the inverse design of metasurfaces in specific and nanophotonic structures in general. [ABSTRACT FROM AUTHOR]

Unusual optical properties of laser-ablated metal surfaces arise from the excitation of local plasmon resonances in nano- and microstructures produced by laser-processing and from the mutual interaction of those structures through surface plasmon polariton (SPP) waves. This interaction provides a synergistic effect, which can make the optical properties of the composite nanostructure drastically different from the properties of its elements. At the same time, the prediction and analysis of these properties are hampered by the complexity of the analytical solution to the problem of SPP excitation by surface objects of arbitrary configuration. Such a problem can be reduced to a simpler one if one considers the geometry of a structured surface as a superposition of harmonic Fourier components. Therefore, the analytical solution to the problem of surface plasmon polariton excitation through the scattering of light by a sinusoidally perturbed plasmonic metal/vacuum boundary becomes very important. In this work, we show that this problem can be solved using a well-known method for calculating guided-mode amplitudes in the presence of current sources, which is used widely in the waveguide theory. The calculations are carried out for the simplest 2D cases of (1) a sinusoidal current of finite length and (2) a finite-length sinusoidal corrugation on a plasmonic metal surface illuminated by a normally incident plane wave. The analytical solution is compared with the results of numerical simulations. It is shown that, in the first case, the analytical and numerical solutions agree almost perfectly. In the second case, the analytical solution correctly predicts the optimum height of the corrugation x opt , providing the maximum SPP excitation efficiency. At the same time, the analytical and numerical values of the SPP amplitude agree very well when the corrugation height x turns out to be x ≪ x opt or x ≫ x opt (at least up to 3 x opt ); at x = x opt , the mismatch of those does not exceed 25%. The limitations of the analytical model leading to such a mismatch are discussed. We believe that the presented approach is useful for modeling various phenomena associated with SPP excitation. [ABSTRACT FROM AUTHOR]

Large varieties of mathematical programming models have been developed to provide decision support to the design engineer. The paper deals with some of the problems and offers practical solutions. [ABSTRACT FROM AUTHOR]

Pulping machines are an integral part of production lines for the processing fruits and vegetables. To meet the ever-growing demand for these agricultural products, it is necessary to introduce innovative solutions to modernize equipment not only for increasing its productivity but also for ensuring its safety. The article proposes a pulping machine that helps to increase the productivity by using the entire area of the sieve drum. The productivity also depends on reliable and safe equipment operation, elimination of downtime during product pulping. One of the main factors affecting the reliable and safe operation is the pressure of pulped product on the walls of the sieve drum, and this pressure depends on the product density. It has been experimentally shown that the density of pulped product can vary significantly even for different varieties of vegetable marrow. As the calculations show, in this case the pressure inside the sieve drum of the pulping machine changes considerably (more than 10%). Therefore, the density of the product should be taken into account when calculating the design parameters of the pulping machine; it helps to ensure its reliable and safe operation and hence to reduce the probability of downtime and to improve the productivity.

A set of measures is taken to protect plants against various diseases and to prevent yield losses. One of the components of such actions is a pre-sowing seed treatment. One of the effective ways of pre-sowing treatment is seeds ozonization, which stimulates their germination and provides the prevention of plant diseases, hence this process increases the germination and the yield of agricultural crops. Our laboratory equipment was made to substantiate the ozonation regimes. Experimental studies on seeds ozonation were carried out for agricultural crop (the zucchini variety Zebra), which is widely used in Russia, particularly in the natural-climatic areas of the Urals. Taking into account that high ozone concentrations are dangerous to human health and life (to service personnel), pre-sowing seeds treatment was carried out at relatively safe concentrations (up to 10 mg/m3), paying attention to the tightness of the equipment. Ozone concentrations of 3 mg/m3, 6 mg/m3 and 9 mg/m3 and seed treatment time of 120 min, 240 min, 360 min and 480 min were chosen. The experimental studies have shown, that a rational regime of seeds treatment for obtaining the maximum germination (79.1%), is observed when ozone concentration is 9 mg/m3 and treatment time is 247.7 min. Thus, the developed laboratory equipment helps to determine the rational ozonation regimes for zucchini seeds. It can also be used to determine the rational ozonation regimes for seeds of other crops.

The substitution for Arg168His (R168H) in γ-tropomyosin (TPM3 gene, Tpm3.12 isoform) is associated with congenital muscle fiber type disproportion (CFTD) and muscle weakness. It is still unclear what molecular mechanisms underlie the muscle dysfunction seen in CFTD. The aim of this work was to study the effect of the R168H mutation in Tpm3.12 on the critical conformational changes that myosin, actin, troponin, and tropomyosin undergo during the ATPase cycle. We used polarized fluorescence microscopy and ghost muscle fibers containing regulated thin filaments and myosin heads (myosin subfragment-1) modified with the 1,5-IAEDANS fluorescent probe. Analysis of the data obtained revealed that a sequential interdependent conformational-functional rearrangement of tropomyosin, actin and myosin heads takes place when modeling the ATPase cycle in the presence of wild-type tropomyosin. A multistep shift of the tropomyosin strands from the outer to the inner domain of actin occurs during the transition from weak to strong binding of myosin to actin. Each tropomyosin position determines the corresponding balance between switched-on and switched-off actin monomers and between the strongly and weakly bound myosin heads. At low Ca2+, the R168H mutation was shown to switch some extra actin monomers on and increase the persistence length of tropomyosin, demonstrating the freezing of the R168HTpm strands close to the open position and disruption of the regulatory function of troponin. Instead of reducing the formation of strong bonds between myosin heads and F-actin, troponin activated it. However, at high Ca2+, troponin decreased the amount of strongly bound myosin heads instead of promoting their formation. Abnormally high sensitivity of thin filaments to Ca2+, inhibition of muscle fiber relaxation due to the appearance of the myosin heads strongly associated with F-actin, and distinct activation of the contractile system at submaximal concentrations of Ca2+ can lead to muscle inefficiency and weakness. Modulators of troponin (tirasemtiv and epigallocatechin-3-gallate) and myosin (omecamtiv mecarbil and 2,3-butanedione monoxime) have been shown to more or less attenuate the negative effects of the tropomyosin R168H mutant. Tirasemtiv and epigallocatechin-3-gallate may be used to prevent muscle dysfunction. [ABSTRACT FROM AUTHOR]

Here, we introduce and demonstrate nanoprinted all-dielectric nanostructures located on fiber end faces as a novel concept for the efficient coupling of light into optical fibers, especially at multiple incidence angles and across large angular intervals. Taking advantage of the unique properties of the nanoprinting technology, such as flexibly varying the width, height, and gap distance of each individual element, we realize different polymeric axial-symmetric structures, such as double-pitch gratings and aperiodic arrays, placed on the facet of commercial step-index fibers. Of particular note is the aperiodic geometry, enabling an unprecedentedly high average coupling efficiency across the entire angular range up to 80°, outperforming regular gratings and especially bare fibers by orders of magnitude. The excellent agreement between simulation and experiment clearly demonstrates the quality of the fabricated structures and the high accuracy of the nanoprinting process. Our approach enables realizing highly integrated and ready-to-use fiber devices, defining a new class of compact, flexible, and practically relevant all-fiber devices beyond the state-of-art. Applications can be found in a variety of cutting-edge fields that require highly efficient light collection over selected angular intervals, such as endoscopy or quantum technologies. Furthermore, fiber functionalization through nanoprinting represents a promising approach for interfacing highly complex functional photonic structures with optical fibers. [ABSTRACT FROM AUTHOR]

A significant proportion of internal transportation of goods is carried out by road. Statistics show that a large number of road traffic accidents, including fatalities, have to do with the driver falling asleep behind the wheel. A method was developed to stop the driver from falling asleep behind the wheel and a device to implement it; as a result, a patent for an invention was obtained. Some experimental studies were realized to implement this method and ensure the functioning of the device. As an example, the results of an experiment with KAMAZ 55102 motor vehicle were quoted, including the measure of the steering wheel angle (αBH = 4,6°) above which it is considered as steering of the wheel operator. In addition to that, the value of the minimum allowable number of steerings of the awake operator in a unit of time was given, and it came up to 0.5 steerings a second. Based on the experimental studies, some theoretical dependences describing the operation of the device preventing the driver from falling asleep at the wheel of a vehicle were developed.

Noise pollution remains a challenging problem requiring the development of novel systems for noise insulation. Extensive work in the field of acoustic metamaterials has led to various ventilated structures which, however, are usually demonstrated for rather narrow regions of the audible spectrum. In this work, the idea of metamaterial‐based systems is further extended, developing the concept of a metahouse chamber representing a ventilated structure for multiple band noise insulation. Broad stop‐bands originate from strong coupling between pairs of Helmholtz resonators constituting the structure. The averaged transmission −18.6 dB are demonstrated numerically and experimentally within the spectral range from 1500 to 16 500 Hz. The sparseness of the structure together with the possibility to use optically transparent materials suggest that the chamber may be also characterized by partial optical transparency depending on the mutual position of structural elements. The obtained results are promising for development of novel noise‐insulating structures advancing urban science. [ABSTRACT FROM AUTHOR]

Tumor acidity is one of the cancer hallmarks and is associated with metabolic reprogramming and the use of glycolysis, which results in a high intracellular lactic acid concentration. Cancer cells avoid acid stress major by the activation and expression of proton and lactate transporters and exchangers and have an inverted pH gradient (extracellular and intracellular pHs are acid and alkaline, respectively). The shift in the tumor acid–base balance promotes proliferation, apoptosis avoidance, invasiveness, metastatic potential, aggressiveness, immune evasion, and treatment resistance. For example, weak-base chemotherapeutic agents may have a substantially reduced cellular uptake capacity due to “ion trapping”. Lactic acid negatively affects the functions of activated effector T cells, stimulates regulatory T cells, and promotes them to express programmed cell death receptor 1. On the other hand, the inversion of pH gradient could be a cancer weakness that will allow the development of new promising therapies, such as tumor-targeted pH-sensitive antibodies and pH-responsible nanoparticle conjugates with anticancer drugs. The regulation of tumor pH levels by pharmacological inhibition of pH-responsible proteins (monocarboxylate transporters, H+-ATPase, etc.) and lactate dehydrogenase A is also a promising anticancer strategy. Another idea is the oral or parenteral use of buffer systems, such as sodium bicarbonate, to neutralize tumor acidity. Buffering therapy does not counteract standard treatment methods and can be used in combination to increase effectiveness. However, the mechanisms of the anticancer effect of buffering therapy are still unclear, and more research is needed. We have attempted to summarize the basic knowledge about tumor acidity. [ABSTRACT FROM AUTHOR]

Gallium phosphide is a low-loss, high-refractive-index semiconductor considered as a promising material for active and passive components in modern nanophotonics. In this work, we show that nanoscale epitaxial layers of GaP with high optical quality can be formed directly on the transparent sapphire wafers despite the symmetry and lattice constant mismatch. This is achieved using a two-step growth technique through the framework of a domain matching epitaxy mechanism. Direct molecular beam epitaxial growth enables the control of material properties and layer thickness with subnanometer precision and allows us to obtain (111)-oriented epitaxial layers of GaP on high-optical-contrast sapphire wafers without the use of postgrowth layer transfer techniques. The influence of growth conditions on the structural quality of GaP-on-sapphire is revealed using Raman spectroscopy and X-ray diffraction reciprocal space mapping. We study the impact of the growth procedure employing a low-temperature seeding layer on the GaP layer morphology and structural quality. Spectroscopic ellipsometry measurements confirm that both the refractive index and the absorption coefficient of the epitaxial GaP layers are close to those of bulk GaP crystals. We also discuss how the GaP layer morphology and structural quality affect its optical density, drawing special attention to the mechanisms of optical losses. Finally, by nanostructuring the grown layer, we fabricate single GaP nanoantennas and confirm their highly resonant optical response in the visible spectral range, thus confirming the feasibility of the reported technology for various nanophotonic applications. [ABSTRACT FROM AUTHOR]

A multisensor data fusion algorithm based on a multilayer neural network is presented for sea ice classification in the winter period. The algorithm uses European Remote Sensing (ERS), RADARSAT synthetic aperture radar (SAR), and low-resolution television camera images and image texture features. Based on a set of in situ observations made at the Kara Sea, a neural network is trained, and its structure is optimized using a pruning method. The performance of the algorithm with different combinations of input features (sensors) is assessed and compared with the performance of a linear discriminant analysis (LDA)-based algorithm. We show that for both algorithms a substantial improvement can be gained by fusion of the three different types of data (91.2% for the neural network) as compared with single-source ERS (66.0%) and RADARSAT (70.7%) SAR image classification. Incorporation of texture increases classification accuracy. This positive effect of texture becomes weaker with increasing number of sensors (from 8.4 to 6.4 percent points for the use of two and three sensors, respectively). In view of the short training time and smaller number of adjustable parameters, this result suggests that semiparametric classification methods can be considered as a good alternative to the neural networks and traditional parametric statistical classifiers applied for the sea ice classification. Index Terms--Data fusion, European Remote Sensing (ERS), neural network, RADARSAT, satellite remote sensing, sea ice classification, synthetic aperture radar (SAR).