2022 - Publications Repository - Gdańsk University of Technology

Show publications from the year

Publications from the year 2022

Show all

Thermal dewetting as a method of surface modification of the gold thin films for surface plasmon resonance based sensor applications
- Marcin Łapiński
- Robert Kozioł
- Agnieszka Zawadzka
- Wojciech Sadowski
- Barbara Kościelska
2022 Materials Today Communications
Here, we report a quick and simple approach with low, optimized production costs to obtain surface plasmon resonance (SPR) based sensors fabricated through a time- and resource-effective method based on thermal dewetting of thin Au films. From the applicative point of view, the method of detection presented here should be easier to implement, since light transmission measurements seem to be much less challenging than light refractive index changes measurements conducted by many authors. Metallic films with nanometric thickness were deposited by magnetron sputtering method on a Corning 1737 glass substrates. Plasmonic nanostructures were formatted as a result of thermal annealing of the films. The detection repeatability, selectivity, and sensibility of manufactured devices were investigated. For this purpose, many verification tests were performed. The quality of the plasmonic nanostructures used for the detection was examined by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and ultraviolet-visible spectroscopy (UV–VIS). X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) spectra showed the absence of any signs of structure degradation after several cycles of detection in the liquid environment. The surface plasmon resonance position of the achieved sensors was linearly changeable in correlation with the ethanol concentration, which translates into their high robustness. Such a simply prepared sensing device showed key features desired in the detection in the liquids area, which opens up the possibility of large-scale commercial production
Thermal Energy Development in Magnetohydrodynamic Flow Utilizing Titanium Dioxide, Copper Oxide and Aluminum Oxide Nanoparticles: Thermal Dispersion and Heat Generating Formularization
- Muhammad Bilal Hafeez
- Marek Krawczuk
- Wasim Jamshed
2022 Full text Frontiers in Energy Research
The main aim of this article heat transfer in thermal engineering deals with the production, use, transformation, and transfer of thermal energy. Engineering and industrial fields including food packaging, the production of food additives, electronic cooling, microturbines, etc. heavily rely on heat transmission. Due to its intriguing potential in industries like the production of polymers, paper, crystal glass, etc., scientists from all over the world have endeavored to investigate the effect of heat transmission on fluid flows past an expandable surface.
Thermal Instability of Choline Chloride-Based Deep Eutectic Solvents and Its Influence on Their Toxicity─Important Limitations of DESs as Sustainable Materials
- Mateusz Marchel
- Hubert Cieśliński
- Grzegorz Boczkaj
2022 Full text INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
Deep eutectic solvents (DESs) have become a hot topic in many branches of science due to their remarkable properties. They have been studied in a wide variety of applications. In particular, choline chloride (ChCl)-based DESs are one of the most commonly used representatives of these fluids. Nevertheless, in order to apply DESs in some fields, it is essential to guarantee their stability, reusability, and biocompatibility. In this context, the long-term stability of three ChCl-based DESs formed using glucose, malonic acid, and urea as hydrogen bond donors was investigated. Furthermore, the possible formation of toxic byproducts during long-term heating was evaluated for the first time, and toxicological studies using three bacterial strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) were performed. ChCl:urea DES revealed a high long-term thermal stability and was also found to be less toxic to the bacteria and thus can be considered as green solvent. ChCl:glucose DES started to decompose as a result of possible caramelization at 100 °C, and decomposition was further promoted at more elevated temperatures. Degradation of this DES did not affect greatly the toxicity toward bacteria, and low antibacterial properties were observed. The applicability of ChCl:malonic DES is not recommended as this DES was shown to be thermally unstable due to esterification and decomposition of malonic acid into acetic acid and carbon dioxide. Moreover, high toxicity of this DES in comparison to other DESs assayed in this study was reported.
Thermal properties of a cement composite containing phase change materials (PCMs) with post-pyrolytic char obtained from spent tyres as a carrier
- Michał Ryms
- Katarzyna Januszewicz
- Elżbieta Haustein
- Paweł Kazimierski
- Witold Lewandowski
2022 ENERGY
This work examines the possible use of post-pyrolysis char made from spent vehicle tyres as a carrier for phase change materials (PCM), which could be used as an additive to cement mortar. Because of the ability of PCM to accumulate heat, the cement composite obtained from it, apart from its structural and strength properties, will acquire an additional energy storage function, which can be very important for energy-saving construction. In the development of the new cement composite, Rubitherm RT22 was used as a PCM. Rubitherm's phase change temperature is within the range (ca 17–25 °C) of temperature fluctuations in buildings. Systematic comparative tests were carried out in order to evaluate the thermal properties of the new cement composite containing 0.67, 2.00, 3.33, 4.67 and 6.67% of char, which contains 32% PCM, i.e. the maximum amount that can be permanently absorbed without activation. These tests included calorimetric measurements of the influence of the composite's composition on the cumulative specific heat, and took phase change effects into consideration. The results of the experiments showed that the use of tyre char as a PCM carrier in cement mortars is not only possible, but also thermodynamically advantageous.
Thermal visualization of Ostwald-de Waele liquid in wavy trapezoidal cavity: Effect of undulation and amplitude
- Ahmad Hijaz
- Rashid Mahmood
- Muhammad Bilal Hafeez
- Afraz Hussain Majeed
- Sameh Askar
- Hasan Shahzad
2022 Full text Case Studies in Thermal Engineering
The present study is concerned with the numerical simulations of Ostwald-de Waele fluid flow in a wavy trapezoidal cavity in the presence of a heated cylinder situated at the center of the cavity. The work consists in characterizing the mixed convection as a function of the intensity of heat flow. The flow behaviour and temperature distribution in a cavity are the main focus of this study. The lower wall of the cavity is fixed and heated while the wavy surface is insulated and moves with a constant speed. The sloping walls are kept cold and are subject to zero no-slip conditions for velocity components. The whole setup is modeled as a set of coupled partial differential equations and is solved by the Finite Element Method. For pressure and velocity approximations, we use the stable finite element pair , while for temperature approximation we use the space of linear polynomial as The ranges of the parameters involved in the study are the Ostwald-de Wale index , Prandlt number Grashof number , the number of undulation , and the non-dimensional amplitude of the wavy surface . The major findings of the study are shown using velocity profile, streamlines, and isotherms. Moreover, the kinetic energy and average Nusselt number is determined for various values of the parameters involved.
Thermally activated persulfate-based Advanced Oxidation Processes — recent progress and challenges in mineralization of persistent organic chemicals: a review
- Shirish H. Sonawane
- Manoj P Rayaroth
- Vividha K. Landge
- Kirill Fedorov
- Grzegorz Boczkaj
2022 Full text Current Opinion in Chemical Engineering
Thermally activated persulfate (TAP) finds application in Advanced Oxidation Processes for the removal of pollutants from contaminated water and soil. This paper reviewed the various cases of TAP in the environmental remediation. The pollutants such as individual pharmaceuticals, biocides, cyclic organic compounds, and dyes are considered in this review. It is interesting to note that most of the organic compounds undergo complete degradation at a high temperature of 70°C with a first-order reaction kinetics. The influence of operating parameters such as temperature, persulfate concentration, initial pH, and degradation behavior in the presence of natural water constituents are also discussed. In addition, several processes to reduce the temperature of TAP are highlighted.
Thermodynamic study of binary mixtures of 2-propanol with ionic liquids, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexylammonium bis(trifluoromethylsulfonyl)imide
- Dorota Warmińska
- Iwona Cichowska-Kopczyńska
2022 JOURNAL OF CHEMICAL THERMODYNAMICS
In this work, densities, speeds of sound, refractive indices and viscosities of three binary mixtures containing the ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexyl-ammonium bis(trifluoromethylsulfonyl)imide, mixed with 2-propanol at wide temperature and composition ranges at atmospheric pressure have been measured. From these experimental data, the excess molar volume, excess molar compressibility, deviation in refractive index and deviation in viscosity have been calculated. Excess properties have been correlated with the composition data using Redlich-Kister polynomial equation. The effects of temperature, cation and anion of ionic liquid on the physicochemical properties were analysed and discussed in terms of intermolecular interactions occurring in the studied systems. The Prigogine-Flory-Patterson theory was examined for suitability for the correlation of excess molar volumes with compositions.
Thermomechanical and Fire Properties of Polyethylene-Composite-Filled Ammonium Polyphosphate and Inorganic Fillers: An Evaluation of Their Modification Efficiency
- Mateusz Barczewski
- Aleksander Hejna
- Kamila Sałasińska
- Joanna Aniśko
- Adam Piasecki
- Katarzyna Skórczewska
- Jacek Andrzejewski
2022 Full text Polymers
The development of new polymer compositions characterized by a reduced environmental impact while lowering the price for applications in large-scale production requires the search for solutions based on the reduction in the polymer content in composites’ structure, as well as the use of fillers from sustainable sources. The study aimed to comprehensively evaluate introducing low-cost inorganic fillers, such as copper slag (CS), basalt powder (BP), and expanded vermiculite (VM), into the flame-retarded ammonium polyphosphate polyethylene composition (PE/APP). The addition of fillers (5–20 wt%) increased the stiffness and hardness of PE/APP, both at room and at elevated temperatures, which may increase the applicability range of the flame retardant polyethylene. The deterioration of composites’ tensile strength and impact strength induced by the presence of inorganic fillers compared to the unmodified polymer is described in detail. The addition of BP, CS, and VM with the simultaneous participation of APP with a total share of 40 wt% caused only a 3.1, 4.6, and 3 MPa decrease in the tensile strength compared to the reference value of 23 MPa found for PE. In turn, the cone calorimeter measurements allowed for the observation of a synergistic effect between APP and VM, reducing the peak heat rate release (pHRR) by 60% compared to unmodified PE. Incorporating fillers with a similar thermal stability but differing particle size distribution and shape led to additional information on their effectiveness in changing the properties of polyethylene. Critical examinations of changes in the mechanical and thermomechanical properties related to the structure analysis enabled the definition of the potential application perspectives analyzed in terms of burning behavior in a cone calorimetry test. Adding inorganic fillers derived from waste significantly reduces the flammability of composites with a matrix of thermoplastic polymers while increasing their sustainability and lowering their price without considerably reducing their mechanical properties, which allows for assigning developed materials as a replacement for flame-retarded polyethylene in large-scale non-loaded parts.
Three-Dimensional Fractography for Conventional and Additive Manufactured Steels After Bending-Torsion Fatigue
- Wojciech Macek
- Ricardo Branco
- Jarosław Trembacz
- José Domingos Costa
- J. A. M. Ferreira
- Carlos Capela
2022 Structural Integrity
In this study, fracture surface topography parameters were measured to investigate the effects of multiaxial loading. In order to assess the metrological aspects of fracture for notched specimens made of high-strength steels processed by both conventional and additively manufacturing (AM) techniques, an optical surface profilometer was used. Three bending moment to torsion moment ratios (B/T) were studied, i.e. 2, 1 and 2/3. The geometries were solid round bars with lateral notches made of conventional steel and hollow round bars with transversal holes for AM specimens. The investigations indicate that arithmetical mean height, Sa, decreased and fractal dimension, Df, increased with higher B/T ratios and higher fatigue lives.
Three-dimensional Weyl topology in one-dimensional photonic structures
- Kosmas L. Tsakmakidis
- Tomasz Stefański
2022 Full text Light-Science & Applications
Topological features, in particular distinct band intersections known as nodal rings, usually requiring three-dimensional structures, have now been demonstrated experimentally in an elegantly simple one-dimensional photonic crystal.
Time reversal invariant single-gap superconductivity with upper critical field larger than the Pauli limit in NbIr2B2
- Debarchan Das
- Karolina Górnicka
- Zurab Guguchia
- Jan Jaroszynski
- Robert J. Cava
- Weiwei Xie
- Hubertus Luetkens
- Tomasz Klimczuk
2022 PHYSICAL REVIEW B
Recently, compounds with noncentrosymmetric crystal structure have attracted much attention for providing a rich playground in search for unconventional superconductivity. NbIr2B2 is a new member to this class of materials harboring superconductivity below Tc = 7.3(2) K and a very high upper critical field that exceeds Pauli limit. Here we report on muon spin rotation (μSR) experiments probing the temperature and field dependence of effective magnetic penetration depth in this compound. Our transverse-field-μSR results suggest a fully gapped s-wave superconductivity. Furthermore, the estimated high value of the upper critical field is also supplemented by high-field transport measurements. Remarkably, the ratio Tc/λ−2 (0) obtained for NbIr2B2 (∼2) is comparable to those of unconventional superconductors. Zero-field μSR data reveal no significant change in the muon spin relaxation rate above and below Tc, evincing that time-reversal symmetry is preserved in the superconducting state. The presented results will stimulate theoretical investigations to obtain a microscopic understanding of the origin of superconductivity with preserved time-reversal symmetry in this unique noncentrosymmetric system.
Titanium lanthanum three oxides decorated magnetic graphene oxide for adsorption of lead ions from aqueous media
- Mosleh Nazanin
- Parham Joolaei Ahranjani
- Parandi Ehsan
- Hamid Rashidi Nodeh
- Nicole Nawrot
- Shahabaldin Rezania
- Sathishkumar Palanivel
2022 ENVIRONMENTAL RESEARCH
The current study presents a viable and straightforward method for synthesizing titanium lanthanum three oxide nanoparticles (TiLa) and their decoration onto the ferrous graphene oxide sheets to produce FeGO-TiLa as efficient magnetic adsorbent. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibration sample magnetometer (VSM) were used to evaluate the physical and chemical properties of the produced nanocomposites. The FeGO-TiLa was used to enhance the removal of lead ions from aqueous solution. The FeGO-TiLa nanocomposite exhibited a much higher removal efficiency (93%) for lead ions than pure TiLa nanoparticles (81%) and magnetic graphene oxide (74%). The influence of FeGO-TiLa dosage, contact time, solution pH, solution temperature, and starting quantity on the lead ions was evaluated and adjusted. The investigations demonstrated that a pH 6 with 40 mg adsorbent resulted in >91% removal of lead ions at ambient temperature after 120 min. Isotherm models were used to analyze experimental results, and Langmuir model fitted the data well as compared Freundlich model with a maximum adsorption capacity of 109.89 mg g−1. Kinetic and studies are performed the lead adsorption over FeGO-TiLa follow pseudo-second-order rate. Langmuir and Free energy suggested the lead ions uptake with FeGO-TiLa was monolayer and physical adsorption mechnaism, respectively. Finally, the FeGO-TiLa nanocompoiste can be used as an alternative adsorbent for water remediation.
Ti/TiO2 nanotubes sensitized PbS quantum dots as photoelectrodes applied for decomposition of anticancer drugs under simulated solar energy
- Paweł Mazierski
- Patrycja Wilczewska
- Wojciech Lisowski
- Tomasz Klimczuk
- Anna Białk-Bielińska
- Adriana Zaleska-Medyska
- Ewa Siedlecka
- Aleksandra Pieczyńska
2022 Full text JOURNAL OF HAZARDOUS MATERIALS
One of the challenges in research into photoelectrocatalytic (PEC) degradation of pollutants is finding the appropriate photoanode material, which has a significant impact on the process efficiency. Among all others, photoelectrodes based on an ordered TiO2 nanotube arrays are a promising material due to well-developed surface area and efficient charge separation. To increase the PEC activity of this material, the SILAR method was used to decorate Ti/TiO2 nanotubes by PbS quantum dots (QD). The ifosfamide (IF) degradation rate constants was twice as higher for PbS-Ti/TiO2 (0.0148 min 1) than for Ti/TiO2 (0.0072 min 1). Our research showed the highest efficiency of PEC degradation of drugs using IIIPbS-Ti/TiO2 made with 3 SILAR cycles (PbS QD size mainly 2–4 nm). The 4 and 6 of SILAR cycles resulted in the aggregation of PbS nanoparticles on the Ti/ TiO2 surface and decreased IF PEC degradation rate to 0.0043 and 0.0033 min 1, respectively. Research on PEC mechanism has shown that the drugs are degraded mainly by the activity of photogenerated holes and hydroxyl radicals. In addition, the identified drug intermediates made possible to propose a degradation pathways of anticancer drugs and the ecotoxicity test show no inhibition of Lemna minor growth of treated solutions.
Tolerance Optimization of Antenna Structures by Means of Response Feature Surrogates
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2022 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
Fabrication tolerances and other types of uncertainties, e.g., the lack of precise knowledge of material parameters, have detrimental effects on electrical and field performance of antenna systems. In the case of input characteristics these are particularly noticeable for narrow- and multi-band antennas where deviations of geometry parameters from their nominal values lead to frequency shifts of the operating frequency bands. Improving design robustness is therefore important yet challenging. On the one hand, it is numerically demanding as it involves uncertainty quantification (UQ), in particular, estimation and improvement of appropriately defined statistical performance metrics. On the other hand, it has to be carried out at the level of full-wave electromagnetic (EM) simulation models, which incurs considerable computational expenses. Executing UQ tasks at practically acceptable costs can be realized using surrogate modeling methods; however, construction of reliable metamodels is hindered by the curse of dimensionality. This paper proposes a novel approach to robust design of antenna structures, where the task is formulated to increase the maximum values of parameter deviations for which 100-percent fabrication yield is ensured. Low cost of the optimization process is enabled by incorporating feature-based regression models for rapid yield estimation, as well as the employment of the trust-region framework for adaptive adjustment of design relocation but also as a convergence safeguard. Our methodology is validated using three microstrip antennas, including two dual-band and a triple-band structure.
Tolerance-Aware Multi-Objective Optimization of Antennas by Means of Feature-Based Regression Surrogates
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2022 Full text IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
Assessing the immunity of antenna design to fabrication tolerances is an important consideration, especially when the manufacturing process has not been predetermined. At the same time, the antenna parameter tuning should be oriented toward improving the performance figures pertinent to both electrical (e.g., input matching) and field properties (e.g., axial ratio bandwidth) as much as possible. Identification of available trade-offs between the robustness and nominal performance can be realized through multi-objective optimization (MO), which is an intricate and computationally expensive task. This paper proposes a novel technique for fast tolerance-aware MO of antenna structures. The key component of the presented methodology is a feature-based regression surrogate, established based on the characteristic points of antenna responses extracted from its electromagnetic (EM)-simulation data, and employed for a rapid estimation of the maximum allowed input tolerance levels for given values of performance parameters of interest. Subsequent trade-off designs are generated by tuning the antenna parameters for various assumed values of relevant figures of interest (e.g., the operating bandwidth). As demonstrated using three microstrip antennas, a rendition of performance-robustness trade-off designs can be accomplished at the cost of just about forty (for six-parameter antenna) to about eighty (for fourteen-parameter antenna) per design EM analyses of the respective structure. Reliability of the approach is validated through direct EM-driven Monte Carlo analysis at the selected designs.
Tolerance-Aware Optimization of Microwave Circuits by Means of Principal Directions and Domain-Restricted Metamodels
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
- Ullah Ubaid
2022 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
Practical microwave design is most often carried out in the nominal sense. Yet, in some cases, performance degradation due to uncertainties may lead to the system failing to meet the prescribed specifications. Reliable uncertainty quantification (UQ) is therefore important yet intricate from numerical standpoint, especially when the circuit at hand is to be evaluated using electromagnetic (EM) simulation tools. Tolerance-aware design (e.g., yield improvement) is even more challenging. This paper introduces a methodology for low-cost surrogate-based yield optimization of passive microwave components. The novelty of the proposed approach, and, at the same time, its major acceleration factor is to span the metamodel model domain with the selected principal vectors, characterized by significant response variability within operating frequency bands of the component under design. This results in a volume-wise constriction of the domain (thereby lower cost of the surrogate model setup) without restricting its size along the relevant directions of the parameter space. Consequently, our technique is a one-shot approach for yield optimization that does not require neither domain relocation nor surrogate re-construction. Our methodology is demonstrated using two microstrip components, and favorably compared to benchmark metamodeling techniques in terms of the computational cost of the yield maximization procedure. The average cost is only 130 EM simulations of the respective circuit, versus the average of 800 and over 360 analyses for the benchmark procedures. At the same time, its reliability is verified by means of EM-based Monte Carlo simulation.
Tool Wear Monitoring Using Improved Dragonfly Optimization Algorithm and Deep Belief Network
- Leo Gertrude David
- Raj Kumar Patra
- Przemysław Falkowski-Gilski
- Parameshachari Bidare Divakarachari
- Lourdusamy Jegan Antony Marcilin
2022 Full text Applied Sciences-Basel
In recent decades, tool wear monitoring has played a crucial role in the improvement of industrial production quality and efficiency. In the machining process, it is important to predict both tool cost and life, and to reduce the equipment downtime. The conventional methods need enormous quantities of human resources and expert skills to achieve precise tool wear information. To automatically identify the tool wear types, deep learning models are extensively used in the existing studies. In this manuscript, a new model is proposed for the effective classification of both serviceable and worn cutting edges. Initially, a dataset is chosen for experimental analysis that includes 254 images of edge profile cutting heads; then, circular Hough transform, canny edge detector, and standard Hough transform are used to segment 577 cutting edge images, where 276 images are disposable and 301 are functional. Furthermore, feature extraction is carried out on the segmented images utilizing Local Binary Pattern (LBPs) and Speeded up Robust Features (SURF), Harris Corner Detection (HCD), Histogram of Oriented Gradients (HOG), and Grey-Level Co-occurrence Matrix (GLCM) feature descriptors for extracting the texture feature vectors. Next, the dimension of the extracted features is reduced by an Improved Dragonfly Optimization Algorithm (IDOA) that lowers the computational complexity and running time of the Deep Belief Network (DBN), while classifying the serviceable and worn cutting edges. The experimental evaluations showed that the IDOA-DBN model attained 98.83% accuracy on the patch configuration of full edge division, which is superior to the existing deep learning models.
Topical delivery of pharmaceutical and cosmetic macromolecules using microemulsion systems
- Patrycja Szumała
- Adam Macierzanka
2022 INTERNATIONAL JOURNAL OF PHARMACEUTICS
Microemulsions are transparent, thermodynamically stable colloidal systems. Over the recent years, they have been increasingly investigated due to their potential as skin delivery vehicles for a wide range of drug molecules. The nanoscale particle size and the specificity of microemulsion components are the main features determining the skin permeation process. However, in order to effectively cross the skin barrier, the active substance itself should also meet a number of requirements, such as relatively small molecular weight, high lipophilicity with certain polarity as well as a specific partition coefficient. This review focuses on recent advancements in topical microemulsion systems related to the transport of active ingredients into the skin, including those with high molecular weight and high polarity. Selected studies have shown that permeation of therapeutic macromolecules can be increased by the correct (i.e. tailored to a specific drug) design of the microemulsion. The degree of skin penetration as well as the kinetics and the site of drug release can be controlled by appropriate qualitative and quantitative selections of penetration promoters (microemulsion components), the structure of microemulsion and its viscosity. The drug-carrier interactions can also affect the effectiveness of microemulsion formulation. These relations have been described and evaluated in this review article.
Topochemical, Single‐Crystal‐to‐Single‐Crystal [2+2] Photocycloadditions Driven by Chalcogen‐Bonding Interactions
- Jan Alfuth
- Olivier Jeannin
- Marc Fourmigué
2022 Full text ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
The face-to-face association of (E)-1,2-di(4-pyridyl)ethylene (bpen) molecules into rectangular motifs stabilized for the first time by chalcogen bonding (ChB) interactions is shown to provide photoreactive systems leading to cyclobutane formation through single-crystal-to-single-crystal [2+2] photodimerizations. The chelating chalcogen bond donors are based on original aromatic, ortho-substituted bis(selenocyanato)benzene derivatives 1–3, prepared from ortho-diboronic acid bis(pinacol) ester precursors and SeO2 and malononitrile in 75–90% yield. The very short intramolecular Se···Se distance in 1–3 (3.22–3.24 Å), a consequence of a strong intramolecular ChB interaction, expands to 3.52–3.54 Å in the chalcogen-bonded adducts with bpen, a distance (< 4 Å) well adapted to the face-to-face association of the bpen molecules into reactive position toward photochemical dimerization.
Topological extraordinary optical transmission
- Konstantinos Baskourelos
- O. Tsilipakos
- Tomasz Stefański
- S. F. Galata
- E. N. Economou
- M. Kafesaki
- Kosmas L. Tsakmakidis
2022 Full text Physical Review Research
Τhe incumbent technology for bringing light to the nanoscale, the near-field scanning optical microscope, has notoriously small throughput efficiencies of the order of 10^4-10^5 or less. We report on a broadband, topological, unidirectionally guiding structure, not requiring adiabatic tapering and, in principle, enabling near-perfect (∼100%) optical transmission through an unstructured single arbitrarily subdiffraction slit at its end. Specifically, for a slit width of just λeff/72 (λ0/138) the attained normalized transmission coefficient reaches a value of 1.52, while for a unidirectional-only (nontopological) device the normalized transmission through a λeff/21 (∼λ0/107) slit reaches 1.14; both limited only by inherent material losses, and with zero reflection from the slit. The associated, under ideal (ultralow-loss) conditions, near-perfect optical extraordinary transmission has implications, among diverse areas in wave physics and engineering, for high-efficiency, maximum-throughput nanoscopes and heat-assisted magnetic recording devices.