Triangle Ring Research Articles

Environmental biotransformation mechanisms by flavin-dependent monooxygenase: A computational study

The enzyme-catalyzed metabolic biotransformation of xenobiotics plays a significant role in toxicology evolution and subsequently environmental health risk assessment. Recent studies noted that the phase I human flavin-dependent monooxygenase (e.g., FMO3) can catalyze xenobiotics into more toxic metabolites. However, details of the metabolic mechanisms are insufficient. To fill the mechanism in the gaps, the systemic density functional theory calculations were performed to elucidate diverse FMO-catalyzed oxidation reactions toward environmental pollutants, including denitrification (e.g., nitrophenol), N-oxidation (e.g., nicotine), desulfurization (e.g., fonofos), and dehalogenation (e.g., pentachlorophenol). Similar to the active center compound 0 of cytochrome P450, FMO mainly catalyzed reactions with the structure of the tricyclic isoalloxazine C-4a-hydroperoxide (FADHOOH). As will be shown, FMO-catalyzed pathways are more favorable with a concerted than stepwise mechanism; Deprotonation is necessary to initiate the oxidation reactions for phenolic substrates; The regioselectivity of nicotine by FMO prefers the N-oxidation other than N-demethylation pathway; Formation of the P–S–O triangle ring is the key step for desulfurization of fonofos by FMO. We envision that these fundamental mechanisms catalyzed by FMO with a computational method can be extended to other xenobiotics of similar structures, which may aid the high-throughput screening and provide theoretical predictions in the future.

Hydrogenated Boron Phosphide THz-Metamaterial-Based Biosensor for Diagnosing COVID-19: A DFT Coupled FEM Study.

Recent reports focus on the hydrogenation engineering of monolayer boron phosphide and simultaneously explore its promising applications in nanoelectronics. Coupling density functional theory and finite element method, we investigate the bowtie triangle ring microstructure composed of boron phosphide with hydrogenation based on structural and performance analysis. We determine the carrier mobility of hydrogenated boron phosphide, reveal the effect of structural and material parameters on resonance frequencies, and discuss the variation of the electric field at the two tips. The results suggest that the mobilities of electrons for hydrogenated BP monolayer in the armchair and zigzag directions are 0.51 and 94.4 cm2·V-1·s-1, whereas for holes, the values are 136.8 and 175.15 cm2·V-1·s-1. Meanwhile, the transmission spectra of the bowtie triangle ring microstructure can be controlled by adjusting the length of the bowtie triangle ring microstructure and carrier density of hydrogenated BP. With the increasing length, the transmission spectrum has a red-shift and the electric field at the tips of equilateral triangle rings is significantly weakened. Furthermore, the theoretical sensitivity of the BTR structure reaches 100 GHz/RIU, which is sufficient to determine healthy and COVID-19-infected individuals. Our findings may open up new avenues for promising applications in the rapid diagnosis of COVID-19.

Improving the electrochemical activity of PdSe2 by constructing P/T structural interfaces

Palladium diselenide (PdSe2) is acknowledged as a potential electrocatalyst for hydrogen evolution reaction (HER), but its large-scale basal plane is catalytically inert, which enormously limits its application in electrochemical efficiency. Here we employ the phase interface in PdSe2 to activate sites on the basal plane and improve the HER activity. Five P/T interface structures in PdSe2 are constructed and optimized by density functional theory (DFT) calculations. The interface boundaries consist of triangle, pentagonal and hexagonal rings with the formation of more Se-Se bonds. The structural stability and HER activity for these interface structures are evaluated, and the optimal sites for HER are confirmed, which are mostly located on Se atoms. Our proposed strategy proves the formation of interface in PdSe2 could successfully enhance its HER performance and could be also applicable to the other two-dimensional materials.

Development of new triangle fast directional switch for high power millimeter wave

A new fast directional switch for high power millimeter waves without frequency modulation was proposed. The principle is a triangle ring resonator of circular corrugated waveguides with a vibrating reflector. The switching frequency was obtained up to 300 Hz by a single vibration reflector. The deformed waveforms of the output powers were observed at large amplitude vibrations of a reflector.

Polarization-independent and angle-insensitive tunable electromagnetically induced transparency in terahertz metamaterials.

A metamaterial with a polarization-independent and angle-insensitive electromagnetically induced transparency (EIT)-like effect is theoretically investigated in the terahertz regime. The proposed metamaterial is composed of square rings and split isosceles triangle rings, which behave as bright elements and quasi-dark elements, respectively. An EIT-like phenomenon, which is caused by the destructive interference between different scattering paths via the bright and quasi-dark elements, is observed with a transparent window. This EIT mechanism is revealed with simulated field distributions as well as the analysis based on coupled-mode theory. Full wave simulations show that EIT-like phenomenon in the proposed metamaterial is independent of polarization and is robust to the angle of the incident light. This structure may have potential applications in terahertz detectors, sensors, and modulators.

Prediction Model for Information Dissemination in Social Network Media Based on Triangle Ring Attractor

In order to solve the information transfer of social network media, a new information transfer prediction method is presented by a triangle ring attractor. At first, the description method of social media information is given in this model, and the evaluation indexes such as information recall rate, matching degree, and recall rate are emphatically expounded. At the same time, the characteristics of media information are analyzed with a triangular ring attractor, and an information transfer prediction model is established. Finally, through the simulation experiment, the key factors influencing the method are deeply analyzed. Experimental results show that compared with other algorithms, this method has good adaptability in the degree of information attenuation and information checking rate.

Three-dimensional Kagome graphene networks and their topological properties

Kagome graphene is a single-layer carbon nanosheet possessing Kagome bands. Here, we propose two types of three-dimensional (3D) Kagome graphene networks (KGNs), which are formed by linking one-dimensional (1D) Kagome graphene nanoribbons. The carbon allotropes show good stabilities although they are completely made of triangle rings. Their cohesive energies are smaller than that of T-carbon approximate 0.3 eV/atom. Remarkably, the new structures exhibit interesting topological properties. The first type of KGN (KGN-1) inherits electronic properties of Kagome graphene. It has two sets of orbital-frustration-induced Kagome bands, and crossings between the bands lead to three kinds of nodal rings, i.e., type I, type II and a critical phase between them. These nodal rings can be observed successively by hole doping. The second type of KGN (KGN-2) is a topological metal. There exist a coexisting phase of a nodal surface and two nodal lines in the momentum space, which are originated from the quantum states in the 1D nanoribbons. In addition, two kinds of electron channels are found in KGN-2.

The adsorption mechanism and electronic properties of FeO–HNCO clusters

The configurations, electronic and spin of the FeO–HNCO clusters are investigated at PW91 method. The calculated results show that the Fe–O–C–N four-member ring preferred to form the FeO–HNCO cluster and it has higher kinetic stability. The isomer which possesses an Fe–O–C triangle ring has higher kinetic activity. The hybridization of sp orbital of C and N atoms of the FeO–HNCO clusters is stronger. For the lowest-energy FeO–HNCO cluster, the Fe and O atoms have the opposite spin direction.

Features of multi-slice spiral CT examination of indirect and direct and femoral inguinal hernia in adults

Features of multi-slice spiral CT examination of indirect and direct and femoral inguinal hernia in adults

A design of equilateral triangular ring SIW cavity‐backed slot antenna for multiband applications

AbstractAn equilateral triangle ring slot antenna with substrate‐integrated waveguide (SIW) cavity‐backed and multiband characteristics is presented in this article. The proposed antenna consists of an equilateral triangular‐ring slot on the top layer of the substrate, an equilateral triangular ground plane on the bottom and an equilateral triangle SIW cavity. The proposed antenna is fed by a probe. By tuning the position of feeding point, four bands are generated by four different modes which are TM10, TM22, TM12, and TM33. The measured results of the prototype have a good agreement with simulation.

Ab initio structure determination of n-diamond.

A systematic computational study on the crystal structure of n-diamond has been performed using first-principle methods. A novel carbon allotrope with hexagonal symmetry R32 space group has been predicted. We name it as HR-carbon. HR-carbon composed of lonsdaleite layers and unique C3 isosceles triangle rings, is stable over graphite phase above 14.2 GPa. The simulated x-ray diffraction pattern, Raman, and energy-loss near-edge spectrum can match the experimental results very well, indicating that HR-carbon is a likely candidate structure for n-diamond. HR-carbon has an incompressible atomic arrangement because of unique C3 isosceles triangle rings. The hardness and bulk modulus of HR-carbon are calculated to be 80 GPa and 427 GPa, respectively, which are comparable to those of diamond. C3 isosceles triangle rings are very important for the stability and hardness of HR-carbon.

Carbon kagome lattice and orbital-frustration-induced metal-insulator transition for optoelectronics.

A three-dimensional elemental carbon kagome lattice, made of only fourfold-coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60° bond angles in the triangle rings, widely perceived to be energetically unfavorable, the carbon kagome lattice is found to display exceptional stability comparable to that of C(60). The system allows us to study the effects of triangular frustration on the electronic properties of realistic solids, and it demonstrates a metal-insulator transition from that of graphene to a direct gap semiconductor in the visible blue region. By minimizing s-p orbital hybridization, which is an intrinsic property of carbon, not only the band edge states become nearly purely frustrated p states, but also the band structure is qualitatively different from any known bulk elemental semiconductors. For example, the optical properties are similar to those of direct-gap semiconductors GaN and ZnO, whereas the effective masses are comparable to or smaller than those of Si.

Synthesis, Characterizations, Magnetism and Thermal Degradation of a 2‐Fold Interpenetrated 3D Cobalt‐Organic Framework

AbstractA new coordination polymer, [Co2(L)2(4,4′‐bipy)]n·3nH2O (1) based on 5‐(3‐methyl‐5‐phenyl‐4H‐1,2,4‐triazol‐4‐yl)isophthalic acid (H2L) and 4,4′‐bipyridine (4,4′‐bipy) has been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, XRPD, IR, and elemental analysis. Temperature‐dependent magnetic susceptibility and thermal degradation for 1 were also studied. The asymmetric unit of compound 1 consists of two crystallographically independent Co(II) ion, two L2− ligand, one 4,4′‐bipy ligand, and three lattice water molecules. The 2D triangle networks were linked by the bridging 4,4′‐bipy ligand to give rise to a 2‐fold interpenetrated 3D architecture. The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II) cations and three L2− ligands. So we can define Co(II) ions as 4‐connected nodes and the L2− ligands as 3‐connected nodes. Thus, the 3D structure can be described as a 2‐fold parallel interpenetrated ins InS 3,4‐conn topology.

K 6 carbon: A metallic carbon allotrope in sp3 bonding networks

We identify by first-principles calculations a new cubic carbon phase in I4132 (O(8)) symmetry, named K6 carbon, which has a six atom primitive cell comprising sp(3) hybridized C3 triangle rings. The structural stability is verified by phonon mode analysis. The calculated elastic constants show that the K6 carbon is a high ductile material with a density even lower than graphite. Electronic band and density of states calculations reveal that it is a metallic carbon allotrope with a high electronic density of states of ∼0.10 states/eV per atom at the Fermi level. These results broaden our understanding of the structural and electronic properties of carbon allotropes.

New ultra-wideband (UWB) bandpass filter using triangle-ring multi-mode stub-loaded resonator

This paper presents a new ultra-wideband (UWB) bandpass filter (BPF) with steeply slopes transition band using triangle-ring multi-mode stub-loaded resonator (MM-SLR). The filter consists of a triangle ring multi-mode resonator with a stub-loaded resonator for controlling the two transmission zeros at 2.8/ 11GHz and the asymmetric tight coupled input/output (I/O) lines. There are five resonant modes generated in the UWB passband including two odd modes and three even modes. The two transmission zeros generated by the triangle-ring MM-SLR can effectively improve the passband edge selectivity. The attenuation slope in the lower and higher passband edges of the proposed filter show 160 and 153dB/GHz, respectively. Experimental verification is provided and good agreement has been found between simulation and measurement.

New cubic carbon phase via graphitic sheet rumpling

We identify by ab initio calculations a new cubic carbon phase in $Pa\overline{3}$ (${T}_{h}^{6}$) symmetry, which has a unit cell that comprises eight $s{p}^{3}$-connected C${}_{3}$ triangle rings (thus termed cubic C${}_{3}$). The transformation from graphite occurs via a novel sheet-rumpling mechanism under anisotropic compression along the $a$[100] axis, which is distinct from the usual $c$-axis compression mechanism for the graphite-to-diamond transition. Calculated structural parameters and simulated x-ray diffraction of cubic C${}_{3}$ match the experimental data, thus resolving the long-standing problem of structural determination of a new carbon phase [Science 140, 817 (1963)]. The sheet-rumpling pathway unveiled here establishes a new mechanism for structural transformation in layered covalent materials.

Oxidation of a two-dimensional hexagonal boron nitride monolayer: a first-principles study

Two-dimensional (2D) hexagonal boron-nitride oxide (h-BNO) is a structural analogue of graphene oxide. Motivated by recent experimental studies of graphene oxide, we have investigated the chemical oxidation of 2D h-BN sheet and the associated electronic properties of h-BNO. Particular emphasis has been placed on the most favorable site(s) for chemisorption of atomic oxygen, and on the migration barrier for an oxygen atom hopping to the top, bridge, or hollow site on the h-BN surface, as well as the most likely pathway for the dissociation of an oxygen molecule on the h-BN surface. We find that when an oxygen atom migrates on the h-BN surface, it is most likely to be over an N atom, but confined by three neighbor B atoms (forming a triangle ring). In general, chemisorption of an oxygen atom will stretch the B-N bond, and under certain conditions may even break the B-N bond. Depending on the initial location of the first chemisorbed O atom, subsequent oxidation tends to form an O domain or O chain on the h-BN sheet. The latter may lead to a synthetic strategy for the unzipping of the h-BN sheet along a zigzag direction. A better understanding of the oxidation of h-BN sheet has important implications for tailoring the properties of the h-BN sheet for applications.

Rectangular Slot with a Novel Triangle Ring Microstrip Feed for UWB Applications

This paper presents a study of a rectangular slot antenna for ultrawide-band (UWB) applications. Antenna is fed by a triangle ring microstrip line. The frequency band considered is 3.1–10.6 GHz, which has approved by the Federal Communications Commission as a commercial UWB band. The proposed antenna has a VSWR less than 2, phase linearity, and gain flatness over the above frequency band.

Li 3 – O – Li 3 molecule: A metal-nonmetal-metal sandwichlike compound with a distending electron cloud

The D3d and D2d isomers of the Li3-O-Li3 molecule are metal-nonmetal-metal sandwichlike structures that contain two Li3 superalkali atoms. Their geometries and the real frequencies are obtained at the CCSD(T)/aug-cc-pVDZ level. They are different from the traditional types of the nonmetal-metal-nonmetal sandwich compounds. The natural bond orbital calculation and the topological property nabla2rho(r) calculation indicate that they are typical ionic compounds. In two isomers, the O2- anion is sandwiched in between two Li3+ cation rings. However, the different orientations of two Li3+ planes give the D3d isomer its own special characteristics. Under the action of the O2- anion in the center, the valence electrons of the D3d isomer are pushed out from two Li3+ triangle rings. This special interaction causes three phenomena. First, the valence electron clouds are distended. Second, the vertical ionization energy of the D3d isomer is considerably low, 4.39 eV, so that it may also be viewed as a superalkali atom. Third, we find that the D3d isomer owns the out-of-plane aromaticity and the largest negative nucleus-independent chemical shift value (-10.8 ppm) exists at 2.5 A above the center of the Li3+ ring, not at the center of the Li3+ ring like the isolated aromatic Li3+ cation.

Design of novel laser cavity with diffractive phase elements

A new method based on the general theory of amplitude-phase retrieval is proposed for designing the diffractive phase elements (DPEs) used in the laser cavity that can produce the desired mode with the specified shape of beam. Simulation results show that the laser cavity with the designed DPEs can successfully generate uniform square and triangle ring patterns. The loss of these fundamental modes is negligibly small and the separation of adjacent transverse modes is large enough to discriminate the fundamental mode from the higher-order modes.