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Wyniki wyszukiwania dla: VEHICLE-TO-VEHICLE COMMUNICATIONS
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Modelling and simulations in time-fractional electrodynamics based on control engineering methods
PublikacjaIn this paper, control engineering methods are presented with regard to modelling and simulations of signal propagation in time-fractional (TF) electrodynamics. That is, signal propagation is simulated in electromagnetic media described by Maxwell’s equations with fractional-order constitutive relations in the time domain. We demonstrate that such equations in TF electrodynamics can be considered as a continuous-time system of...
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Microfluidically Frequency-Reconfigurable Self-Quadruplexing Antenna Based on Substrate Integrated Square-Cavity
PublikacjaIn this article, a novel concept of self-quadruplexing tunable antenna (SQTA) enabled by microfluidic channels is investigated. The operating channels are either filled with air or dielectric liquids to enable frequency tunability. The proposed SQTA is implemented on the substrate-integrated square-cavity (SISC). A swastika-shaped slot is milled on the top-surface of the SISC to create four quarter-mode resonators. The resonators...
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Excitation of Circularly Polarized Wave via Single-Feed Metasurface-Integrated Compact Antenna for Internet of Things
PublikacjaA compact circularly polarized (CP) quasi-omnidirectional antenna is introduced for internet of things (IoT). The structure consists of two components implemented on FR-4 substrates, and sep-arated by an air gap: one printed with a rectangular patch fed through a matching network, and another with a metasurface and a ground plane. Two different methods for impedance matching are employed. An equivalent circuit model of the antenna...
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Recent advances of selected passive heat transfer intensification methods for phase change material-based latent heat energy storage units: A review
PublikacjaThe following article overviews recent studies regarding heat transfer enhancement methods, explicitly focusing on fins and coils utilization, in phase change material-based latent heat thermal energy storage systems. It discusses the influence of various geometrical and material parameters on the melting and solidification processes, as well as the orientation of the heat transfer surface within the storage tank. Additionally,...
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Application of a hybrid finite difference-mode matching method to the analysis of circular cavities loaded with cylindrical metallic objects
PublikacjaW artykule przedstawiono badania rezonatorów cylindrycznych zawierających obiekty cylindryczne o dowolnym przekroju poprzecznym z wykorzystaniem metody hybrydowej stanowiącej połączenie metody różnic skończonych z metodą dopasowania rodzajów. W ramach badań określono częstotliwości rezonansowe dla wybranych struktur rezonatorów. Wyniki numeryczne zostały zweryfikowane eksperymentalnie.
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Microstrip four-port circulator using a ferrite coupled line section
PublikacjaThis paper describes an alternative configuration of a four-port circulator realized in a microstrip ferrite coupled line technology. The proposed fully planar device employs two three-port circulators consisting of a ferrite coupled line junction and T junction. Both circulators are connected through the same arm, hence, the problem of anti-parallel magnetization met in this type of circulators is avoided without the increase...
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Comparative analysis of various transformation techniques for voiceless consonants modeling
PublikacjaIn this paper, a comparison of various transformation techniques, namely Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT) and Discrete Walsh Hadamard Transform (DWHT) are performed in the context of their application to voiceless consonant modeling. Speech features based on these transformation techniques are extracted. These features are mean and derivative values of cepstrum coefficients, derived from each transformation....
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On the regularity of the displacement sequence of an orientation preserving circle homeomorphism
PublikacjaWe investigate the regularity properties of the displacemnet sequence of an orientation preserving circle homeomorphism. is rational, then ηn(z) is asymptotically periodic with semi-period q. This
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Characteristics of the polarised off-body channel in indoor environments
PublikacjaThis paper addresses the depolarisation effect in off-body body area networks channels, based on measurements performed at 2.45 GHz in an indoor environment. Seven different scenarios, involving both static and dynamic users, were considered, taking a statistical perspective. The analysis of the cross-polarisation discrimination is performed, as well as the analysis of path loss in co- and cross-polarised channels. Results show...
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Discrete and continuous fractional persistence problems – the positivity property and applications
PublikacjaIn this article, we study the continuous and discrete fractional persistence problem which looks for the persistence of properties of a given classical (α=1) differential equation in the fractional case (here using fractional Caputo’s derivatives) and the numerical scheme which are associated (here with discrete Grünwald–Letnikov derivatives). Our main concerns are positivity, order preserving ,equilibrium points and stability...
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Generalization of Kramers-Krönig relations for evaluation of causality in power-law media
PublikacjaClassical Kramers-Krönig (K–K) relations connect real and imaginary parts of the frequency-domain response of a system. The K–K relations also hold between the logarithm of modulus and the argument of the response, e.g. between the attenuation and the phase shift of a solution to a wave-propagation problem. For square-integrable functions of frequency, the satisfaction of classical K–K relations implies causality in the time domain....
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On possible applications of media described by fractional-order models in electromagnetic cloaking
PublikacjaThe purpose of this paper is to open a scientific discussion on possible applications of media described by fractional-order (FO) models (FOMs) in electromagnetic cloaking. A 2-D cloak based on active sources and the surface equivalence theorem is simulated. It employs a medium described by FOM in communication with sources cancelling the scattered field. A perfect electromagnetic active cloak is thereby demonstrated with the use...
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Design-oriented modeling of antenna structures by means of two-level kriging with explicit dimensionality reduction
PublikacjaThe employment of full-wave electromagnetic (EM) analysis is a practical necessity in the design of contemporary antenna structures. This is because simpler models are generally not available or of limited accuracy. At the same time, EM-based design is computationally expensive. Consequently, the ways of accelerating tasks such as parametric optimization or uncertainty quantification have to be sought. A possible workaround that...
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Comments on various extensions of the Riemann–Liouville fractional derivatives : About the Leibniz and chain rule properties
PublikacjaStarting from the Riemann–Liouville derivative, many authors have built their own notion of fractional derivative in order to avoid some classical difficulties like a non zero derivative for a constant function or a rather complicated analogue of the Leibniz relation. Discussing in full generality the existence of such operator over continuous functions, we derive some obstruction Lemma which can be used to prove the triviality...
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Accelerated design optimization of miniaturized microwave passives by design reusing and Kriging interpolation surrogates
PublikacjaElectromagnetic (EM) analysis has become ubiquitous in the design of microwave components and systems. One of the reasons is the increasing topological complexity of the circuits. Their reliable evaluation—at least at the design closure stage—can no longer be carried out using analytical or equivalent network representations. This is especially pertinent to miniaturized structures, where considerable EM cross-coupling effects occurring...
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Adaptive Positioning Systems Based on Multiple Wireless Interfaces for Industrial IoT in Harsh Manufacturing Environments
PublikacjaAs the industrial sector is becoming ever more flexible in order to improve productivity, legacy interfaces for industrial applications must evolve to enhance efficiency and must adapt to achieve higher elasticity and reliability in harsh manufacturing environments. The localization of machines, sensors and workers inside the industrial premises is one of such interfaces used by many applications. Current localization-based systems...
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Cost-Efficient Surrogate Modeling of High-Frequency Structures Using Nested Kriging with Automated Adjustment of Model Domain Lateral Dimensions
PublikacjaSurrogate models are becoming popular tools of choice in mitigating issues related to the excessive cost of electromagnetic (EM)-driven design of high-frequency structures. Among available techniques, approximation modeling is by far the most popular due to its versatility. In particular, the surrogates are exclusively based on the sampled simulation data with no need to involve engineering insight or problem-specific knowledge....
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Design-oriented computationally-efficient feature-based surrogate modelling of multi-band antennas with nested kriging
PublikacjaDesign of modern antenna structures heavily depends on electromagnetic (EM) simulation tools. EM analysis provides reliable evaluation of increasingly complex designs but tends to be CPU intensive. When multiple simulations are needed (e.g., for parameters tuning), the aggregated simulation cost may become a serious bottleneck. As one possible way of mitigating the issue, the recent literature fosters utilization of faster representations,...
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Low-cost performance-driven modelling of compact microwave components with two-layer surrogates and gradient kriging
PublikacjaUtilization of electromagnetic (EM) simulation tools has become indispensable for reliable evaluation of microwave components. As the cost of an individual analysis may already be considerable, the computational overhead associated with EM-driven tasks that require massive simulations (e.g., optimization) may turn prohibitive. One of mitigation methods is the employment of equivalent network models. Yet, they are incapable of accounting...
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Double-diffusive natural convection energy transfer in magnetically influenced Casson fluid flow in trapezoidal enclosure with fillets
PublikacjaThe prime motive of this disquisition is to deal with mathematical analysis of natural convection energy transport driven by combined buoyancy effects of thermal and solutal diffusion in a trapezoidal enclosure. Casson fluid rheological constitutive model depicting attributes of viscoelastic liquids is envisioned. The influence of the inclined magnetic field governed by Lorentz field law is also considered. To raise the essence...
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High Isolation Metamaterial-based Dual-band MIMO Antenna for 5G Millimeter-wave Applications
PublikacjaThis article presents a high-isolation metamaterial-based dual-band multiple-input multiple-output (MIMO) antenna for 5G millimeter-wave communication networks. The proposed antenna is a pentagon-shaped monopole that provides a dual-band response with a wide operating bandwidth at 5G 28/28 bands. The antenna is printed on 0.508-mm-thick Rogers RT5880 substrate of relative permittivity ɛr =2.2. It exhibits a small physical size...
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A finite element analysis of thermal energy inclination based on ternary hybrid nanoparticles influenced by induced magnetic field
PublikacjaThe use of hybrid nanoparticles to improve thermal processes is a key method that has implications for a variety of interventions utilized in many sectors. This paper aimed to look into the impacts of ternary nanoparticles on hyperbolic tangent materials to establish their thermal characteristics. Flow describing equations have been explored in the presence of heat production, non-Fourier heat flux, and an induced magnetic field....
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Selection of circuit geometry for miniaturized microwave components based on concurrent optimization of performance and layout area
PublikacjaThe paper presents a framework for automated EM-driven circuit geometry selection of miniaturized microwave components. Selection of a particular layout is based directly on miniaturization rates achieved for a set of candidate circuit geometries. Size reduction of the considered structures is obtained by replacing their main building blocks (i.e., conventional transmission lines) with slow-wave composite cells and meander lines....
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Electromagnetic-based derivation of fractional-order circuit theory
PublikacjaIn this paper, foundations of the fractional-order circuit theory are revisited. Although many papers have been devoted to fractional-order modelling of electrical circuits, there are relatively few foundations for such an approach. Therefore, we derive fractional-order lumped-element equations for capacitors, inductors and resistors, as well as Kirchhoff’s voltage and current laws using quasi-static approximations of fractional-order...
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Signal propagation in electromagnetic media described by fractional-order models
PublikacjaIn this paper, signal propagation is analysed in electromagnetic media described by fractional-order (FO) models (FOMs). Maxwell’s equations with FO constitutive relations are introduced in the time domain. Then, their phasor representation is derived for one-dimensional case of the plane wave propagation. With the use of the Fourier transformation, the algorithm for simulation of the non-monochromatic wave propagation is introduced....
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TDOA versus ATDOA for wide area multilateration system
PublikacjaThis paper outlines a new method of a location service (LCS) in the asynchronous wireless networks (AWNs) where the nodes (base stations) operate asynchronously in relation to one another. This method, called asynchronous time difference of arrival (ATDOA), enables the calculation of the position of the mobile object (MO) through the measurements taken by a set of non-synchronized fixed nodes and is based on the measurement of...
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Justification of quasi-stationary approximation in models of gene expression of a self-regulating protein
PublikacjaWe analyse a model of Hes1 gene transcription and protein synthesis with a negative feedback loop. The effect of multiple binding sites in the Hes1 promoter as well as the dimer formation process are taken into account. We consider three, possibly different, time scales connected with: (i) the process of binding to/dissolving from a binding site, (ii) formation and dissociation of dimers, (iii) production and degradation of Hes1...
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Low-cost multiband four-port phased array antenna for sub-6 GHz 5G applications with enhanced gain methodology in Radio-over-fiber systems using modulation instability
PublikacjaPhased array antenna (PAA) technology is essential for applications requiring high gain and wide bandwidth, such as sensors, medical, and 5G. Achieving such a design, however, is a challenging and intricate process that calls for precise calculations and a combination of findings to alter the phase and amplitude of each unit. Furthermore, coupling effects between these PAA structure elements can only be completed with the use of...
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Multi-instrument analysis of L-band amplitude scintillation observed over the Eastern Arabian Peninsula
PublikacjaThe study of scintillation-causing ionospheric irregularities is important to mitigate their effects on satellite communications. It is also important due to the spatial and temporal variability of these irregularities, given that their characteristics differ from one region to another. This study investigates the spatial and temporal characteristics of L1 amplitude scintillation-causing ionospheric irregularities over the Eastern...
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A Comprehensive Survey on Antennas On-Chip Based on Metamaterial, Metasurface, and Substrate Integrated Waveguide Principles for Millimeter-Waves and Terahertz Integrated Circuits and Systems
PublikacjaAntennas on-chip are a particular type of radiating elements valued for their small footprint. They are most commonly integrated in circuit boards to electromagnetically interface free space, which is necessary for wireless communications. Antennas on-chip radiate and receive electromagnetic (EM) energy as any conventional antennas, but what distinguishes them is their miniaturized size. This means they can be integrated inside...
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UWB Microstrip Antennas on a Cylindrical Surfaces
PublikacjaConformal antennas are becoming popular due to their many advantages and possibilities of applications they offer. The advantages of using antennas with a curved surface arise not only from the possibility of integrating them with the object on which they are mounted on but also from the increase, relatively to planar antennas, of their visible angular range. The circular antenna arrays, or arrays of radiators located on the surface...
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A Novel Versatile Decoupling Structure and Expedited Inverse-Model-Based Re-Design Procedure for Compact Single-and Dual-Band MIMO Antennas
PublikacjaMultiple-input multiple-output (MIMO) antennas are considered to be the key components of fifth generation (5G) mobile communications. One of the challenges pertinent to the design of highly integrated MIMO structures is to minimize the mutual coupling among the antenna elements. The latter arises from two sources, the coupling in the free space and the coupling currents propagating on a ground plane. In this paper, an array of...
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Improved-Efficacy EM-Based Antenna Miniaturization by Multi-Fidelity Simulations and Objective Function Adaptation
PublikacjaThe growing demands for integration of surface mount design (SMD) antennas into miniatur-ized electronic devices have been continuously imposing limitations on the structure dimen-sions. Examples include embedded antennas in applications such as on-board devices, picosatel-lites, 5G communications, or implantable and wearable devices. The demands for size reduction while ensuring a satisfactory level of the electrical and field...
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Dynamic Re-Clustering Leach-Based (Dr-Leach) Protocol for Wireless Sensor Networks
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Network-aware Data Prefetching Optimization of Computations in a Heterogeneous HPC Framework
PublikacjaRapid development of diverse computer architectures and hardware accelerators caused that designing parallel systems faces new problems resulting from their heterogeneity. Our implementation of a parallel system called KernelHive allows to efficiently run applications in a heterogeneous environment consisting of multiple collections of nodes with different types of computing devices. The execution engine of the system is open for...
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Crystal structures of eight- and ten-membered cyclic bisanisylphosphonothioyl disulfanes and comparison with their P-ferrocenyl analogues
PublikacjaTwo new crystal structures of eight- and ten-membered cyclic bisanisylphosphonothioyl disulfanes, namely 2,5-bis(4-methoxyphenyl)-1,6,3,4,25,55- dioxadithiadiphosphocane-2,5-dithione, C16H18O4P2S4, and 2,5-bis(4-methoxyphenyl)-1,6,3,4,25,55-dioxadithiadiphosphecane-2,5-dithione, C18H22O4P2S4, have been determined and compared to structures of the ferrocenyl analogues. The eight-membered rings have similar conformations (TBC) but...
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Theory and implementation of a virtualisation level Future Internet defence in depth architecture
PublikacjaAn EU Future Internet Engineering project currently underway in Poland defines three parallel internets (PIs). The emerging IIP system (IIPS, abbreviating the project’s Polish name), has a four-level architecture, with level 2 responsible for creation of virtual resources of the PIs. This paper proposes a three-tier security architecture to address level 2 threats of unauthorised traffic injection and IIPS traffic manipulation...
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Crystal structures of (E)-3-(4-hydroxybenzylidene)chroman-4-one and (E)-3-(3-hydroxybenzylidene)-2-phenylchroman-4-one
PublikacjaThe synthesis and crystal structures of (E)-3-(4-hydroxybenzylidene)chroman-4-one, C16H12O3,I, and (E)-3-(3-hydroxybenzylidene)-2-phenylchroman-4-one,C22H16O3,II, are reported. These compounds are of interest with respect to biological activity. Both structures display intermolecular C—H---O and O—H---O hydrogen bonding, forming layers in the crystal lattice. The crystal structure of compound I is consolidated...
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A study of chirality in bis(1,2-dimethoxyethane-κ^2 O,O')sodium bis(tri-tert-butoxysilanethiolato-κ2O,S)sodate
PublikacjaPraca prezentuje analizę samoorganizacji związku kompleksowego z prostszych jonów na przykładzie silanotiolanosodanu bis(dimetoksyetan)sodu. Stwierdzono, że w anionie (RS)2Na- obie grupy tri-tert-butoksysilanotiolanowe mają tę samą skręcalność - obie (P) lub obie (M). Zjawisko to występuje we wszystkich znanych sodanach i litanach zawierających grupę (tert-BuO)3SiS.
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Two pseudopolymorphs of licl trimers with semicubane structures
PublikacjaCząsteczki tytułowych związków w ciele stałym przyjmują strukturę semikubanów - jest to pierwsza tego typu struktura dla solwatowanego chlorku litu. Jej budowę można opisać jako kuban [Li4Cl4(OPEt3)4], w którym jedna z cząsteczek LiCl została usunięta. Brak tej cząsteczki, a dokładniej mostkującego atomu Li, powoduje deformację struktury kubanu. Naroża zdeformowanego kubanu stanowią trzy atomy litu pochodzące z LiCl oraz cztery...
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Two isomorphic ZnII/CoII complexes with tri-tert-butoxysilanethiol and histamine, and (4-hydroxymethyl-1H-imidazole-κN)bis(tri-tert-butoxysilanethiolato-κ2O,S)zinc(II)
PublikacjaOtrzymano dwa izomorficzne kompleksy cynku(II) i kobaltu(II) z tri-tert-butoksysilanotiolem i histaminą oraz kompleks cynku(II) z tri-tert-butoksysilanotiolem i 4(5)-hydroksymetyloimidazolem. Scharakteryzowano strukturę otrzymanych kompleksów w ciele stałym.
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Two isomorphous ZnII/CoIIcomplexes with tri-tert-butoxysilanethiol and histamine, and (4-hydroxymethyl-1H-imidazole-κN)bis(tri-tert-butoxysilanethiolato-κ2O,S)zinc(II)
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(2,2'-Bipyridine)bis(tri-tert-butoxysilanethiolato-kS)lead(II) and (4,7-diphenyl-1,10-phenanthroline-k2N,N')bis(tri-tert-butoxysilanethiolato-kS)lead(II) benzene hemisolvate
PublikacjaWyznaczono i opisano struktury rentgenowskie tytułowych związków. Atom ołowiu w obu przypadkach wykazuje koordynację typu zniekształconej piramidy kwadratowej o rdzeniu PbON2S2 w której jeden z atomów siarki leży w pozycji osiowej. Struktury są stabilizowane przez oddziaływania międzycząsteczkowe typu pi-pi oraz C-H...pi.
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Supramolecular structures of bis-thionooxalamic acid esters derived from (±)-cyclohexane-1,2-diamine and (±)-1,2-diphenylethylenediamine
PublikacjaZsyntezowano dwa racemiczne estry kwasu bis(tiooksamowego) i zbadano ich sposób upakowania w sieci krystalicznej. Analiza rentgenograficzna monokryształów badanych związków wykazała, że organizują się one w jednowymiarowe struktury, które tworzone są przez molekuły o przeciwnej chiralności, połączone za pomocą trójcentrowych wiązań wodorowych C=S...NH...O=C. Powstające agregaty są dodatkowo stabilizowane przez słabe oddziaływania...
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The 2:1 cocrystal of benzamide and pentafluororbenzoic acid
PublikacjaKrystaliczna struktura centrosymetrycznej supermolekuły składa się z czterech cząsteczek benzamidu oraz dwóch kwasu karboksylowego, które powiązane są ze sobą za pomocą wiązań wodorowych typu O-H...O oraz N-H...O.
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The first compound with an unusual type of anion, [Li(SR)2]-:bis(µ2-aqua-d2)tetrakis(aqua-d2)]dilithium(I)bis[bis(tri-tert-butoxysilanethiolato-k2O,S)lithate(I)]dihydrate-d2
PublikacjaTytułowy związek [Li2(D2O)6][Li(C9H27SSiO3)2]2*2D2O, jest pierwszym związkiem z wiązaniem S-M (M-metal alkaliczny), zawierającym niespotykany typ anionu litanowego: [Li(SR)2]-,gdzie R=Si{OC{CH3)3}3. Centrum symetrii związku znajduję się pośrodku pierścienia Li2O2 wchodzącego w skład kationu. Wszystkie atomy litu budujące rdzenie kationów - LiO4 i anionów - LiO2S2, są czterokoordynacyjne. Jednoujemne aniony [Li(SR)2]- są dobrze...
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Influence of chloroform on crystalline products yielded in reactions of 5,10,15,20-tetraphenylporphyrin with HCl and copper(II) salts
PublikacjaStwierdzono, że chloroform wbudowuje się do sieci krystalicznej dichlorowodorku 5,10,15,20-tetrafenyloporfiryny, oraz że powoduje krystalizację nowej, jednoskośnej odmiany polimorficznej porfirynianu miedzi(II), CuTPP. W pracy opisano strukturę krystaliczną solwatu dichlorowodorku porfiryny z ośmioma cząsteczkami chloroformu, C44H32N42+·2Cl-·8CHCl3, i porównano ją...
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10-Methyl- and 9,10-dimethyl acridinium methyl sulfate
PublikacjaThe title compounds, C(14)H(12)N(+).CH(3)O(4)S(-), (I), and C(15)H(14)N(+).CH(3)O(4)S(-), (II), respectively, crystallize with the planar 10-methylacridinium or 9,10-dimethylacridinium cations arranged in layers, parallel to the twofold axis in (I) and perpendicular to the 2(1) axis in (II). Adjacent cations in both compounds are packed in a 'head-to-tail' manner. The methyl sulfate anion only exhibits planar symmetry in (II)....
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9-Cyano-10-methylacridinium hydrogen dinitrate
PublikacjaThe title compound, C15H11N2+·HN2O6−, crystallizes in the monoclinic space group C2/c with four molecules in the unit cell. The planar 9-cyano-10-methylacridinium cations lie on crystallographic twofold axes and are arranged in layers, almost perpendicular to the ac plane, in such a way that neighbouring molecules are positioned in a `head-to-tail' manner. These cations and the hydrogen dinitrate anions are linked through C—H⋯O...
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9-(Trichloroacetylimino)acridine monohydrate
PublikacjaThe title compound, alternatively called N-acridin-9(10H)-ylidene-2,2,2-trichloroacetamide monohydrate, C15H9Cl3N2O·H2O, crystallizes in space group P21/c with Z = 4. The acridine moieties are arranged in layers, tilted at an angle of 15.20 (4)° relative to the ac plane, while adjacent molecules pack in a head-to-tail manner. Acridine and water molecules form columns along the b axis held in place by a network of hydrogen...