Planar Form Research Articles

σ-Aromaticity in planar pentacoordinate aluminium and gallium clusters

Planar hypercoordinate structures are gaining immense attention due to the shift from common paradigm. Herein, our high level ab initio calculations predict that planar pentacoordinate aluminium and gallium centres in Cu5Al2+ and Cu5Ga2+ clusters are global minima in their singlet ground states. These clusters are thermodynamically and kinetically very stable. Detailed electronic structure analyses reveal the presence of σ-aromaticity which is the driving force for the stability of the planar form.

Boron Silicon B2Si3qand B3Si2pClusters: The Smallest Aromatic Ribbons

The small binary boron silicon clusters B2Si3q with q going from -2 to +2 and B3Si2p with p varying from -3 to +1 were reinvestigated using quantum chemical methods. The thermodynamic stability of these smallest ribbon structures is governed by both Hückel and ribbon models for aromaticity. The more negative the cluster charge, the more ribbon character is shown. In contrast, the more positive the charge state, the more pronounced the Hückel character becomes. The ribbon aromaticity character can also be classified into ribbon aromatic, semiaromatic, antiaromatic, and triplet aromatic when the electron configuration of a ribbon structure is described as [...π2(n+1)σ2n], [...π2n+1σ2n], [...π2nσ2n], and [...π2n+1σ2n-1], respectively. Geometry optimizations of the B2Si3 lowest-energy structure by some density functional theory (DFT) functionals result in a nonplanar shape because it possesses an antiaromatic ribbon character. However, its π aromaticity assigned by the Hückel rule is stronger in such a way that several other DFT and coupled-cluster theory CCSD(T) calculations show that B2Si3 is indeed stable in a planar form (Cs). A new global equilibrium structure for the anion B2Si32-, which is a ribbon semiaromatic species, was identified. Some benchmark tests were also carried out to evaluate the performance of popular methods for the treatment of binary B-Si clusters. At odds with some previous studies, we found that with reference to the high accuracy CCSD(T)/CBS method, the hybrid TPSSh functional is reliable for a structure search, whereas the hybrid B3LYP functional is more suitable for simulations of some experimental spectroscopic results.

Multifunctional and Mechanically Robust Porous Diamond with Large Electroactive Surfaces via Electrically Conductive and Insulating Templates for 3D Electrode Applications

AbstractHighly functional 3D biological systems, which are ordinary in this physical world, suggest that traditional planar/flat materials when assembled into 3D variants, can deliver significantly higher levels of functionality and efficiency. Thanks to its set of unique properties, diamond has received significant recognition as the material of choice for a variety of functional platforms, however, implementation of diamond in real‐world applications has lagged behind alternative materials, which offer a greater degree of versatility. In this regard, for applications to benefit from diamond‐specific properties, approaches on fabrication of diamond beyond the common planar form in a practical and scalable manner are required today. Capitalizing on the ability to synthesize diamond over large areas, this study demonstrates fabrication of porous boron‐doped diamond (BDD) in freestanding form and on wafer‐compatible sizes. Porous BDD electrodes deliver robust electrochemical stability and exceptional electrical characteristics. Aiming to utilize the full potential of diamond properties, this study examines the impact of the BDD porous structure on the ability of electrodes to effectively remove organic pollutants from simulated wastewater and to provide enhanced sensitivity/selectivity of biologically active compounds. This study represents an important step in achieving diamond with extended functionality suitable for industrial/commercial scale implementation.

Professional Training of Future Educators for the Usage of Ethnological-Aesthetic Means in Work with Children of Senior Preschool Age

The relevance of professional training of future educators of IPE (institution of preschool education) for usage ethnological-aesthetic means in work with children is substantiated in the article. The concept of "means" is concretized and a complex of ethnological-aesthetic means, effective for the forming in preschool age children's ideas about culture, life, traditions, customs, rites of the Ukrainian people and aesthetic taste (folk toys, crafts and handicrafts, state and folk symbols, everyday life, arts and crafts) is proposed. Importance of involving senior preschool age children in folk crafts and handicrafts, arts, making folk toys is actualized, which promotes patriotism, development of personal qualities such as kindness, compassion, courage. The role of aesthetics of everyday life, state and national symbols in awareness of the beauty of the surrounding reality by child is determined. The paper suggests theoretical and methodological aspects of professional training of students for decorative drawing and decorative application classes (drawing and application of Easter eggs on planar forms, Yavoriv toys, exercises in elements of Hutsul and Petrykivka painting), making a folk toys from various materials (threads, fabric, hay, straw), modeling visits to a virtual museum in work with senior preschool age children; the importance of such classes for mental, speech development, preparation for schooling of senior preschool age children is substantiated. The pedagogical conditions for the effectiveness of the usage of ethnological-aesthetic means in the practice of institutions of preschool education are proposed. The authors emphasize the importance of training future educators to create an appropriate educational environment, develop skills to select tools and methods for work with children that would promote their creative attitude to the aesthetic development of reality, reflecting it in their own creative activities.

Oxygen Reduction Reaction with Manganese Oxide Nanospheres in Microbial Fuel Cells.

Operating microbial fuel cells (MFCs) under extreme pH conditions offers a substantial benefit. Acidic conditions suppress the growth of undesirable methanogens and increase redox potential for oxygen reduction reactions (ORRs), and alkaline conditions increase the electrocatalytic activity. However, operating any fuel cells, including MFCs, is difficult under such extreme pH conditions. Here, we demonstrate a pH-universal ORR ink based on hollow nanospheres of manganese oxide (h-Mn3O4) anchored with multiwalled carbon nanotubes (MWCNTs) on planar and porous forms of carbon electrodes in MFCs (pH = 3–11). Nanospheres of h-Mn3O4 (diameter ∼ 31 nm, shell thickness ∼ 7 nm) on a glassy carbon electrode yielded a highly reproducible ORR activity at pH 3 and 10, based on rotating disk electrode (RDE) tests. A phenomenal ORR performance and long-term stability (∼106 days) of the ink were also observed with four different porous cathodes (carbon cloth, carbon nanofoam paper, reticulated vitreous carbon, and graphite felt) in MFCs. The ink reduced the charge transfer resistance (Rct) to the ORR by 100-fold and 45-fold under the alkaline and acidic conditions, respectively. The current study promotes ORR activity and subsequently the MFC operations under a wide range of pH conditions, including acidic and basic conditions.

CSiGaAl2 -/0 and CGeGaAl2 -/0 having planar tetracoordinate carbon atoms in their global minimum energy structures.

Density functional theory (DFT) is used to explore the structure, stability, and bonding in CSiGaAl2 -/0 and CGeGaAl2 -/0 systems having planar tetracoordinate carbon (ptC). The neutral systems have 17 valence electrons and the mono-anionic systems have 18 valence electrons. The ab initio molecular dynamics simulations for 2000 fs time at two different temperatures (300 and 500 K) supported the kinetic stability of the systems. From the natural bond orbital (NBO) analysis it is shown that there is a strong electron donation from the ligand atoms to the ptC atom. We have used Li+ ion for the neutralization of the mono-anionic systems and more interestingly it does not disrupt the planar structure. The most preferable site for binding of Li+ ion is along the AlAl bond in both of the mono-anionic systems. All the systems in this work have both σ and π aromaticity which is predicted from the computations of nucleus independent chemical shift (NICS). Although the anionic species obey the 18 valence electronic rule, the neutral systems break the rule with 17 valence electrons. However, both sets of systems are stable in the planar form. The bonding analysis of the systems includes molecular orbital, adaptive natural density partitioning (AdNDP), quantum theory of atoms in molecules (QTAIM), electron localization function (ELF) basin, and aromaticity analyses. The energy decomposition analysis (EDA) determines the interaction of Li+ ion with CSiGaAl2 - and CGeGaAl2 - in Li@SiGaAl2 and Li@GeGaAl2 , respectively.

Tutorial on metalenses for advanced flat optics: Design, fabrication, and critical considerations

Metalenses comprised of artificial subwavelength structures known as meta-atoms have demonstrated abilities beyond conventional bulky optical components by modulating the phase, amplitude, and polarization of light in an ultrathin planar form factor. In this Tutorial, we present the fundamental principles and practical design procedures to exploit the abilities of metalenses, including achromaticity, high numerical aperture, and tunability. The fundamental principles include both plasmonic and dielectric meta-atoms, which require different physics to describe their light–matter interactions. In the phase modulation section, we compare the methods of physically implementing phase via meta-atoms including both the propagation and geometric phase methods. Next, we cover the recent progress of nanofabrication procedures from the perspective of the metalenses using materials such as titanium dioxide, gallium nitride, and hydrogenated amorphous silicon. We further compare the various fabrication methods with regard to the resolution, size, cost, and optical properties of fabricated metalenses. Then, we describe the critical considerations of metalenses including aberration-correction, numerical aperture, and tunability for advanced flat optics. Herein, we provide a practical guide for the design, fabrication, and critical considerations of metalenses with examples of research from early works to more recent developments.

Application of a Comprehensive Rock Slope Stability Assessment Approach for Selected Malaysian Granitic Rock Slopes

In Malaysia, rock slope stability analysis has been largely confined to kinematic analysis with rock mass rating systems as assessment tools for stability analysis. While this method addresses the fundamental issues of rock slope stability including identifying potential failure modes, an information gap still exists between geologists and engineers in designing proper mitigation measures for rock slopes. This paper aims to address this issue by incorporating several methodologies, including kinematic analysis, slope mass rating and the Barton-Bandis criterion for the limit equilibrium method. Four rock slopes with potential instabilities namely KSA, KSB, LHA, and LHB were studied. KSA and KSB were located near Kajang, Selangor while LHA and LHB were located near Rawang, Selangor. Each slope exhibits multiple potential failures, with attention given on sliding-type failures in planar or wedge form. A slope mass rating value was assigned to each potential failure based on rock mass ratingbasic and the slope mass rating based on readjustments for discontinuity orientation and excavation method. Factor of safety from limit equilibrium method show potentially unstable blocks and failed blocks (Factor of Safety <1.00) with confirmation on site. Water filling of discontinuity apertures plays an important role in destabilizing rock blocks, especially in wet conditions experienced in Malaysia’s tropical climate. Several geometries are identified as potentially unstable due to low slope mass rating (Class V) and factor of safety of <1.2, such as planar J5 and wedge J2*J5 at KSA, wedge forming with sets J3, J4 and fault plane at KSB, planar J2 at LHA, and wedge J3*J4 at LHB. Stabilization structures such as rock bolts can be better designed with the determined factor of safety values coupled with relevant geological and geotechnical inputs. In this comprehensive rock slope stability assessment approach, limit equilibrium method serves as a useful method in analyzing rock slope stability to complement kinematic analysis and stability ratings often used in Malaysia.

Controllable synthesis of 0D, 1D, and 2D nano lanthanum borates and their dispersion stabilities and tribological properties in rapeseed oil

0D, 1 D and 2 D nano lanthanum borates were prepared by changing the reaction conditions of the hydrothermal method. The effect of reaction time, pH value, temperature, and reactant molar ratio on the shapes and sizes were investigated. The as-obtained nano lanthanum borates were demonstrated by scanning electron microscope (SEM), FT-IR and water contact angle test. The dispersion stability was then evaluated by a spectrophotometry. Moreover, the tribological properties of the prepared 0 D, 1 D and 2 D nano lanthanum borates as lubricating additives in rapeseed oil were investigated on a four-ball tribo-tester. Furthermore, the contact model and underlying lubricating mechanisms were proposed based on the results of surface analysis. The results indicated that nano lanthanum borates with different shapes and sizes could be obtained by regulating the reaction conditions of a hydrothermal method. Ethanol rapid evaporation ultrasonic dispersion method and stearic acid surface modification could improve the dispersion stability of nano lanthanum borates in rapeseed oil. In addition, the as-obtained 0 D, 1 D and 2 D nano lanthanum borates could significantly facilitate the anti-wear and friction-reducing properties of rapeseed oil, especially for 2 D nanoflakes. The enhanced lubricating performance of 2 D lanthanum borate nanoflakes might be attributed to the combined action of relatively lower loads under planar contact forms, thicker and stronger adsorption film generated by plate-like additives, and the enhanced activity of boron atoms and the increased boron-permeation amount on the friction surface to form tribochemical films containing Fe2O3, B2O3 and La2O3.

Asymmetric guidance of multiple hybrid modes through a gain-loss-assisted planar coupled-waveguide system hosting higher-order exceptional points

The gain-loss-assisted optical systems have revealed an unconventional light manipulation tool by hosting exceptional points (EPs), which has lately a great deal of interest in the photonics community. Here, the emergence of higher-order EPs is investigated in a planar coupled-waveguide geometry, which has the potential to assemble additional degrees of freedom to explore EP-induced light dynamics. A planar form of waveguide array consisting of four high-indexed guides is designed to support multiple quasiguided hybrid modes. An inhomogeneous customized gain-loss profile to couple at least three chosen modes is introduced in such a way that the waveguide hosts an EP of order three with the simultaneous presence of two second-order EPs in the gain-loss parameter plane. We investigate the dynamical parametric encirclement schemes of embedded EPs of different orders and exclusively reveal both the chiral and nonchiral dynamics of light assisted by asymmetric conversions of hybrid modes. The implementation of our findings in discrete photonic systems hosting higher-order EPs indeed opens up a fertile platform to meet a wide range of enticing applications in the context of manipulation of modes including conversion and switching.

Positionally-independent and extended read range resonant sensors applied to deep soil moisture monitoring

Here we detail an inductively coupled extender (ICE) and resonant (LC) sensor to monitor soil moisture using a portable reader. Significant advances of this ICE-LC design are extending typical LC sensor read range over a meter and reducing positional alignment sensitivity between reader and sensor. An analytical model validates the working principle and feasibility of the ICE-LC system. Prototypes of the ICE-LC sensor were built and optimized in terms of sensitivity and power transfer (single and four turns for ICE top and bottom coils, respectively). Soil moisture tests validated the ICE-LC improvements on minimized positional alignment sensitivity and extended read range, transducing a decrease in resonant frequency with increasing soil moisture. When calibrating with existing wired approaches, the ICE-LC sensor had a reproducible, linear sensor gain of 4.52%moisture content/MHz with an R2 of 0.745 and RMSE of 2.41%. A smaller, planar form factor of the ICE-LC sensor was also tested and exhibited reduced positional alignment sensitivity between reader and sensor at shorter read ranges. This initial study demonstrates the feasibility of the ICE-LC resonant sensor as a cost-effective method to monitor soil moisture content throughout the growing season at many field locations.

Synthesis of bilayer borophene.

As the nearest-neighbour element to carbon, boron is theoretically predicted to have a planar two-dimensional form, named borophene, with novel properties, such as Dirac fermions and superconductivity. Several polymorphs of monolayer borophene have been grown on metal surfaces, yet thicker bilayer and few-layer nanosheets remain elusive. Here we report the synthesis of large-size, single-crystalline bilayer borophene on the Cu(111) surface by molecular beam epitaxy. Combining scanning tunnelling microscopy and first-principles calculations, we show that bilayer borophene consists of two stacked monolayers that are held together by covalent interlayer boron-boron bonding, and each monolayer has β12-like structures with zigzag rows. The formation of a bilayer is associated with a large transfer and redistribution of charge in the first boron layer on Cu(111), which provides additional electrons for the bonding of additional boron atoms, enabling the growth of the second layer. The bilayer borophene is shown to possess metallic character, and be less prone to being oxidized than its monolayer counterparts.

A Computational Study of Hydrodynamic Interactions Between Pairs of Sperm With Planar and Quasi-Planar Beat Forms

Although hydrodynamic interactions and cooperative swimming of mammalian sperm are observed, the key factors that lead to attraction or repulsion in different confined geometries are not well understood. In this study, we simulate the 3-dimensional fluid-structure interaction of pairs of swimmers utilizing the Method of Regularized Stokeslets, accounting for a nearby wall via a regularized image system. To investigate emergent trajectories of swimmers, we look at different preferred beat forms, planar or quasi-planar (helical with unequal radii). We also explored different initializations of swimmers in either the same plane (co-planar) or with centerlines in parallel planes. In free space, swimmers with quasi-planar beat forms and those with planar beat forms that are co-planar exhibit stable attraction. The swimmers reach a maintained minimum distance apart that is smaller than their initial distance apart. In contrast, for swimmers initialized in parallel beat planes with a planar beat form, we observe alternating periods of attraction and repulsion. When the pairs of swimmers are perpendicular to a nearby wall, for all cases considered, they approach the wall and reach a constant distance between swimmers. Interestingly, we observe sperm rolling in the case of swimmers with preferred planar beat forms that are initialized in parallel beat planes and near a wall.

Stereomutation in Tetracoordinate Centers via Stabilization of Planar Tetracoordinated Systems

The quest for stabilizing planar forms of tetracoordinate carbon started five decades ago and intends to achieve interconversion between [R]- and [S]-stereoisomers without breaking covalent bonds. Several strategies are successful in making the planar tetracoordinate form a minimum on its potential energy surface. However, the first examples of systems where stereomutation is possible were reported only recently. In this study, the possibility of neutral and dications of simple hydrocarbons (cyclopentane, cyclopentene, spiropentane, and spiropentadiene) and their counterparts with the central carbon atom replaced by elements from groups 13, 14, and 15 are explored using ab initio MP2 calculations. The energy difference between the tetrahedral and planar forms decreases from row II to row III or IV substituents. Additionally, aromaticity involving the delocalization of the lone pair on the central atom appears to help in further stabilizing the planar form compared to the tetrahedral form, especially for the row II substituents. We identified 11 systems where the tetrahedral state is a minimum on the potential energy surface, and the planar form is a transition state corresponding to stereomutation. Interestingly, the planar structures of three systems were found to be minimum, and the corresponding tetrahedral states were transition states. The energy profiles corresponding to such transitions involving both planar and tetrahedral states without the breaking of covalent bonds were examined. The systems showcased in this study and research in this direction are expected to realize molecules that experimentally exhibit stereomutation.

Tuning structural preference of negatively charged B16 by ionically or covalently interacting with alkali and coinage metals

The planar ribbon form is the lowest-energy structure of the neutral and negatively charged B16 clusters, especially planar B162− with ten delocalized π electrons is viewed as an all-boron naphthalene, whereas the doped B16TM− by transition metals unexpectedly exhibit the high coordinated TM-centered tubular structures. We found herein a totally different picture in B16M−/B16TM− (M = Li, Na, K; TM = Ag, Au) doped by s-block metals (being isoelectronic to B162−) relative to the reported B16-based clusters. A new quasi-planar trapezoid structure is predicted to be a global minimum, where B16TM− (TM = Ag, Au) presents chemistry similar to that of hydrogen in its bonding to boron. The chemical bonding and structural integrity of the quasi-planar trapezoid structure is not altered significantly in B16M−, suggesting its stability and viability as a promising building block for boron-assembled nanomaterials.

Preparation, Structure Determination, and Electrochemical Properties of 4,5‐Dialkylbenzo[1,2‐d:4,5‐d’]bis[1,2,3]triselenoles and Their Singlet and Triplet‐State Dications

Abstract4,8‐Dialkylbenzo[1,2‐d:4,5‐d’]bis[1,2,3]triselenoles [alkyl=Et, Bu, and Oc (C8H17)] were first prepared and treated with concentrated sulfuric acid‐d2 to generate benzobistriselenole dications, which were determined by NMR spectroscopy. The oxidation of dioctylbenzobistriselenole with three equivalents of single‐electron oxidizing reagent (NOSbF6) produced the corresponding dication.2SbF6−, and the salt was isolated into a stable form. The ESR spectra of the dications measured in concentrated sulfuric acid in the range of room temperature and −196 °C were observed as split peaks similar to that of solid state dication.2SbF6−. Magnetic susceptibility of the dication.2SbF6− was determined by a superconducting quantum interference device (SQUID) magnetometer, which showed the salt is diamagnetic. The optimized structures and the total energy of the singlet‐ and triplet‐state benzobistriselenole dications were calculated using the density functional theory (DFT) method at the B3LYP6‐311G**(d,p) level. The results revealed that the structures of the singlet‐ and triplet‐state dications calculated have a completely planar forms and the triplet‐state dication is slightly more stable than the singlet‐state one in acetonitrile using a polarizable continuum model (PCM).

Structure and Reactivity of Alloxan Monohydrate in the Liquid Phase.

Alloxan is an important toxic glucose analogue used to induce diabetes in lab test animals. Once regarded as a "problem structure," the condensed-phase structure of anhydrous alloxan has largely been settled, but literature inconsistencies remain for the structure of the typically employed reagent alloxan monohydrate. Due to the criticality of structure-function relationships, we have used 1H/13C{1H} NMR, IR spectroscopy, as well as quantum mechanical (QM) calculations to probe the liquid-phase structure and reactivity of alloxan monohydrate. In protic solvents (D2O and acetic acid-d4), hydration at the C5 carbonyl of alloxan monohydrate occurs quantitatively to form the C5 gem-diol (5,5'-dihydroxybarbituric acid). In the aprotic solvent dimethyl sulfoxide (DMSO)-d6, there exists a mixture of the C5 gem-diol and planar tetraketo form of alloxan monohydrate. QM calculations explain the solvent-dependent hydration reactivity, where a solvent-assisted H-atom transfer mechanism lowers the activation energy of water addition at the C5 carbonyl by ∼16 or 27 kcal/mol in water or acetic acid, respectively, compared to the unassisted hydration reaction. Prompt recrystallization of alloxan monohydrate from boiling water does not alter the structure of the reagent. These findings probe the exact structure of alloxan monohydrate to guide future research efforts in biological sciences and in organic synthesis.

Ion Scattering and Energization in Filamentary Structures Through Earth's Magnetosheath

AbstractMulti‐point measurements on kinetic scales through Earth's magnetosheath have revealed a spectrum of filamentary currents and vortical flows advected with the shocked plasmas outside the magnetopause. The spectral energy density in these structures is correlated with enhanced ion temperatures. Using an empirically derived statistical model based on fluid‐kinetic theory for these structures we demonstrate how they act to scatter magnetosheath ions. Through the combined action of energization in the direction perpendicular to the background magnetic field along chaotic orbits, and pitch‐angle scattering into the parallel direction appreciable ion energization occurs. These dynamics drive heating while generating non‐thermal energetic tails similar to that observed. It is shown how the operation of this process depends on the field topology with deviations from planar form and counter‐propagation required to drive significant energization. This process will modulate ion anisotropies through the magnetosheath independent of both adiabatic effects and the action of anisotropy instabilities.

Development of virtual upcycling fashion design based on 3-dimensional digital clothing technology

The purpose of this study is to develop up-cycling fashion design methods centered on discarded denim material for the study of original up-cycling design methods. Up-cycling fashion design work was developed using digital clothing technology. This is a recent hot topic among sustainable fashion design methods. Up-cycling fashion design expression methods (categorized as dismantlement, collages, depaysement, grafting, weaving, and tearing) were centered on design methods. These methods create various three-dimensional modeling effects in planar forms, whereby five pieces can be applied to the fabric and digitally produced. The results are as follows: First, the use of discarded denim fabric for the development of up-cycling fashion design pieces enabled the recycling of existing resources, provided solutions to environmental pollution problems, and provided expansion opportunities for design processes for sustainable fashion products that expand the design value of denim products and their utility. Second, new eco-friendly fashion designs that attempt to achieve diversity in modern fashion trends could be presented through formative contemporary fashion produced by up-cycling work products. Third, up-cycling fashion design work is expected to provide opportunities for eco-friendly fashion design methods. This will expand the value of sustainable fashion design by recycling simple waste materials through the use of three-dimensional digital clothing technology and further through the presentation of expanded life cycles that extend product planning, production, and life cycles.

Mechanical and Self‐Deformable Spatial Modulation Beam Steering and Splitting Metasurface

AbstractMetasurfaces or artificial electromagnetic structures, offer feasible options to manipulate electromagnetic waves with compact and planar form factors. Tuneable metasurfaces can steer and split the electromagnetic wavefront, and are strongly desirable for many engineering and science applications. However, realizing tuneable metasurfaces that can achieve integrated diversified functionalities is somewhat challenging. This work proposes a simple spatial modulation mechanism to realize beam steering and splitting between left‐handed and right‐handed circularly polarized waves. A prototype proposed structure using 4D printing is fabricated to provide mechanical and self‐deformation flexibility with different operating modes. Underlying concepts are confirmed and verified by theoretical predictions, numerical simulations, and experiments.