Y-shaped Geometry Research Articles

Nontrivial fusion of Majorana zero modes in interacting quantum-dot arrays

Motivated by recent experimental reports of Majorana zero modes (MZMs) in quantum-dot systems at the “sweet spot,” where the electronic hopping th is equal to the superconducting coupling Δ, we study the time-dependent spectroscopy corresponding to the fusion of MZMs. The term “nontrivial” refers to the fusion of Majoranas from different original pairs of MZMs, each with well-defined parities. We employ an experimentally accessible time-dependent real-space local density-of-states (LDOS) method to investigate the nontrivial MZM fusion outcomes in canonical chains and in a Y-shaped array of interacting electrons. In the case of quantum-dot chains where two pairs of MZMs are initially disconnected, after fusion we find equal-height peaks in the electron and hole components of the LDOS, signaling nontrivial fusion into both the vacuum I and fermion Ψ channels with equal weight. For π-junction quantum-dot chains, where the superconducting phase has opposite signs on the left and right portions of the chain, after the nontrivial fusion we observed the formation of an exotic two-site MZM near the center of the chain, coexisting with another single-site MZM. Furthermore, we also studied the fusion of three MZMs in the Y-shaped geometry. In this case, after the fusion we observed the novel formation of another exotic multisite MZM, with properties depending on the connection and geometry of the central region of the Y-shaped quantum-dot array. Published by the American Physical Society 2024

Quantitation of polyethylene glycol by size exclusion chromatography with charged aerosol, differential refractive index, and multi-angle light scattering detectors

Polyethylene glycol (PEG) has found tremendous applications in pharmaceutical products and has played a critical role in PEGylated drug modalities to improve pharmacokinetic properties and biological efficacy. The characterization and quantitation of PEGs are essential to control manufacture process and drug product quality. However, the assay value of PEG could change dramatically depending on the structures of the PEG and the detection techniques used. In this study, we developed a size exclusion chromatographic (SEC) method for quantitative PEG analysis, and we systematically evaluated the performance of three online detectors with different operating principles: a charged aerosol detector (CAD), a differential refractive index (dRI) detector, and a multi-angle light scattering detector (MALS). Fourteen PEG compounds covering a wide range of molecular weight (MW, 1 – 40 kDa) and molecular architectures (linear, branched, Y-shaped and multi-arm geometries) were evaluated by these three detection techniques. Our study revealed that the dRI showed the most universal responses among all the PEGs regardless of their molecular weight or geometries. In the contrast, CAD and MALS detector showed MW-dependent and semi-universal geometry-dependent responses. Another key finding is that the relative response factor for each multi-arm PEG in the CAD and the MALS were inversely correlated, suggesting both can be applied to qualitatively assess polymers of different architectures, including the ones with subtle differences in their core structures. The comparison of the three detectors not only provides the fundamental and comprehensive understanding of PEG quantitation but also enables the process development and control of high-quality PEGs in producing PEGylated therapeutics in the pharmaceutical industry.

Otoacoustic emissions reveal the micromechanical role of organ-of-Corti cytoarchitecture in cochlear amplification

The intricate, crystalline cytoarchitecture of the mammalian organ of Corti presumably plays an important role in cochlear amplification. As currently understood, the oblique, Y-shaped arrangement of the outer hair cells (OHCs) and phalangeal processes of the Deiters cells serves to create differential "push-pull" forces that drive the motion of the basilar membrane via the spatial feedforward and/or feedbackward of OHC forces. In concert with the cochlear traveling wave, the longitudinal separation between OHC sensing and forcing creates phase shifts that yield a form of negative damping, amplifying waves as they propagate. Unlike active forces that arise and act locally, push-pull forces are inherently directional-whereas forward-traveling waves are boosted, reverse-traveling waves are squelched. Despite their attractions, models based on push-pull amplification must contend with otoacoustic emissions (OAEs), whose existence implies that amplified energy escapes from the inner ear via mechanisms involving reverse traveling waves. We analyze hybrid local/push-pull models to determine the constraints that reflection-source OAEs place on the directionality of cochlear wave propagation. By implementing a special force-mixing control knob, we vary the mix of local and push-pull forces while leaving the forward-traveling wave unchanged. Consistency with stimulus-frequency OAEs requires that the active forces underlying cochlear wave amplification be primarily local in character, contradicting the prevailing view. By requiring that the oblique cytoarchitecture produce predominantly local forces, we reinterpret the functional role of the Y-shaped geometry, proposing that it serves not as a push-pull amplifier, but as a mechanical funnel that spatially integrates local OHC forces.

Development and experimental verification of self-centered y-shaped braced frame

A new type of the y-shaped (Y) bracing system composed of three brace members arranged in a y-shaped geometry, frictional mechanism for energy dissipation and pre-compressed axial springs to provide the self-centering capability is developed and studied in this paper. To improve the seismic performance of the self-centered y-shaped (SCY) braced frame, it is designed such that the structural steel members including beam, columns and braces other than the self-centering member remain within the elastic range of steel material leading to protect the structural elements from damages under lateral loading. The mechanics of this system are explained, the equations governing its hysteretic responses are outlined and scaled validation tests of two frames with different geometries are conducted under the condition of reversed cycles of loading. The results of the two tested frames under the quasi static loading show that the SCY braced frame has stable hysteretic loops which ensure a constant level of energy dissipation. Analytical findings which were verified by the results of the experimental tests show that increasing the length of the self-centering element increases the force capacity of the SCY braced frame and the self-centering element experiences the greatest deformation under lateral loading in a specific length and angle.

Dual-Band Circularly Polarized Dielectric Resonator Antenna for WLAN and WiMAX Applications.

In this paper, a new dual-band circularly polarized (CP) dielectric resonator antenna for WLAN and WiMAX applications is proposed. The dielectric resonator has an asymmetric Y-shaped geometry. By properly selecting the length of the arms, the pairs of fundamental (TE) and second-order (TE) are excited separately at the design frequencies to radiate the CP wave. The measurement shows that the fabricated antenna exhibits a wide impedance bandwidth for |S−10 dB of 62.07% (2.2–4.18 GHz). The far-field measurements in the broadside direction demonstrated a dual-band CP response with 3 dB ARBWs of 4.92%(2.38–2.5 GHz) at the lower and 12.64% (3.26–3.70 GHz) at the upper band. The measured CP bands cover the entire frequency range of WLAN (2.401–2.495 GHz) and WiMAX (3.4–3.69 GHz) at the lower and upper bands, respectively.

Novel V- and Y-Shaped Light-Emitting Liquid Crystals with Pentafluorinated Bistolane-Based Luminophores.

Herein, we describe the synthesis of novel light-emitting liquid-crystalline (LC) compounds bearing pentafluorinated bistolane-based luminophores with a V- or a Y-shaped molecular geometry and the evaluation of their LC and photophysical characteristics. The V- or Y-shaped compounds exhibited a unique LC phase and showed photoluminescence (PL) behavior under various circumstances, such as in dilute solution or in the solid state. Notably, PL characteristics were observed even under high-temperature conditions with a crystal (Cr) to LC phase transition, although the PL efficiency (ΦPL) was gradually reduced because of thermal molecular motion. Interestingly, ΦPL was found to be completely recovered through the LC → Cr phase transition during the cooling process; the PL characteristics of the V- or Y-shaped compounds were sensitively changed by external thermal stress, giving these compounds the ability to act as thermoresponsive PL sensing materials.

Low-Fouling Thin Hydrogel Coatings Made of Photo-Cross-Linked Polyzwitterions.

Although zwitterionic chemistries are among the most promising materials for producing nonfouling surfaces, their structural diversity has been low until now. Here, we compare the in vitro fouling behavior of a set of four systematically varied sulfa-/sulfobetaine-containing zwitterionic hydrogel coatings against a series of proteins and nonmotile as well as motile marine organisms as model foulers. The coatings are prepared by simultaneous photoinduced cross-linking and surface anchoring to elucidate the effect of the molecular structure of the zwitterionic moieties on their antifouling activity. Analogously prepared coatings of poly(butyl methacrylate) and poly(oligoethylene glycol methacrylate) serve as references. Photoreactive polymers are synthesized by the statistical copolymerization of sulfobetaine or sulfabetaine methacrylates and methacrylamides with a benzophenone derivative of 2-hydroxyethyl methacrylate and are applied as a thin film coating. While keeping the density of the zwitterionic and cross-linker groups constant, the molecular structure of the zwitterionic side chains is varied systematically, as is the arrangement of the ion pairs in the side chain by changing the classical linear geometry to a novel Y-shaped geometry. All of the polyzwitterions strongly reduce fouling compared to poly(butyl methacrylate). Overall, the sulfabetaine polyzwitterion coatings studiedmatches the high antifouling effectiveness of oligo(ethylene glycol)-based ones used as a control. Nevertheless, performances varied individually for a given pair of polymer and fouler. The case of the polysulfobetaines exemplifies that minor chemical changes in the polymer structure affect the antifouling performance markedly. Accordingly, the antifouling performance of such polymers cannot be correlated simply to the type of zwitterion used (which could be generally ranked as better performing or poorer performing) but is a result of the polymer's precise chemical structure. Our findings underline the need to enlarge the existing structural diversity of polyzwitterions for antifouling purposes to optimize the potential of their chemical structure.

Cochlear amplification and tuning depend on the cellular arrangement within the organ of Corti

The field of cochlear mechanics has been undergoing a revolution due to recent findings made possible by advancements in measurement techniques. While it has long been assumed that basilar-membrane (BM) motion is the most important determinant of sound transduction by the inner hair cells (IHCs), it turns out that other parts of the sensory epithelium closer to the IHCs, such as the reticular lamina (RL), move with significantly greater amplitude for weaker sounds. It has not been established how these findings are related to the complex cytoarchitecture of the organ of Corti between the BM and RL, which is composed of a lattice of asymmetric Y-shaped elements, each consisting of a basally slanted outer hair cell (OHC), an apically slanted phalangeal process (PhP), and a supporting Deiters' cell (DC). Here, a computational model of the mouse cochlea supports the hypothesis that the OHC micromotors require this Y-shaped geometry for their contribution to the exquisite sensitivity and frequency selectivity of the mammalian cochlea. By varying only the OHC gain parameter, the model can reproduce measurements of BM and RL gain and tuning for a variety of input sound levels. Malformations such as reversing the orientations of the OHCs and PhPs or removing the PhPs altogether greatly reduce the effectiveness of the OHC motors. These results imply that the DCs and PhPs must be properly accounted for in emerging OHC regeneration therapies.

A molecular mechanics and ab initio prediction of the 1 H chemical shifts of pinanes.

Molecular mechanics calculations plus the application of a refined Karplus equation gave the conformations of 19 pinanes. These range from a Y-shaped geometry in the apopinene and α-pinene series to a pseudo chair conformation in β-pinene, nopinone and verbanone, a flattened chair in pinocarvone and the pinocarveols and a distorted Y shape for iso-verbanone. These structures were then used as input to predict the 1 H chemical shifts of these compounds by semi-empirical (1 H-NMR spectra (HSPEC)) and ab initio gauge-invariant atomic orbital (GIAO) calculations, the latter at the B3LYP hybrid density functional theory level using 6-31++G** basis set. The two methods gave generally good agreement with the 184 observed shifts with root mean square (RMS) errors 0.07ppm (HSPEC) and 0.10ppm (GIAO), but the GIAO calculations gave several significant (>0.25ppm) errors. One was for the H3 proton in apopinenone and other α,β unsaturated ketones; the others occurred for protons in close proximity to hydroxyl groups. To provide more information, smaller analogues of known geometry and chemical shifts were subject to the same analysis. In cyclopentenone, the Gaussian geometry gave good agreement with the observed shifts, but the MMFF94, MMX and MM3 geometries all gave errors for different protons. These results show clearly that the molecular geometries of the α,β unsaturated ketones are responsible for the errors. The errors for the alcohols were examined using ethanol as model and were shown to be due to the different possible conformations of the OH group. Similar GIAO calculations on substituted methanes gave good agreement for the methyl compounds but poor agreement for di and tri halosubstituted methanes. The aforementioned method of molecular mechanics plus GIAO calculations is shown to be a very useful tool for the investigation of molecular geometries and conformations. However, multihalogen compounds may require different basis sets for accurate calculations. Copyright © 2017 John Wiley & Sons, Ltd.

Associative learning with Y-shaped floating gate transistors operated in memristive modes

We present Y-shaped three-terminal floating gate transistors with positioned quantum dots (QDs) acting as floating gates. The QDs are precisely positioned in the input terminals and the localized charge controls the conductance of the transistors. Connecting two devices enables one to implement associative learning by tuning the QD-charge with two input signals. The number of pulses to develop or to forget the association depends on the widths and amplitudes of the applied voltage pulses. The Y-shaped geometry of the presented device may be considered to implement synaptic functionalities without separating learning and signal transmission in time.

Monomeric Three-Coordinate N-Heterocyclic Carbene Nickel(I) Complexes: Synthesis, Structures, and Catalytic Applications in Cross-Coupling Reactions

A series of three-coordinate monovalent nickel halide complexes bearing N-heterocyclic carbene (NHC) ligands, i.e., NiCl(IPr)(L) [L = pyridine, P(OPh)3, bis(diphenylphosphino)butane (dppb), IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene], NiX(IMes)(PPh3) (X = Cl and Br, IMes = 1,3-bis(mesityl)imidazol-2-ylidene), were prepared. The complexes were identified using NMR spectroscopy, superconducting quantum interference device (SQUID), and X-ray crystallography. Additionally, ESR spectra of NiCl(IPr)(pyridine) were taken in toluene. These complexes had three-coordinate Y-shaped geometries in both the solid and solution states. The compounds containing IPr showed equilibrium between the monomeric and dimeric forms, with liberation of ligands. Addition of 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane to the dinickel(I) IPr complex instead of dppb resulted in heterolytic cleavage to nickel(0) and nickel(II) species. Catalysis of Suzuki cross-coupling and Buchwald–Hartwig aminati...

Influence of the unit Y-shaped microchannel geometry on the capillary flow

Fractal networks are widely applied in the field of heat and mass transfer. As one of the important parts of the fractal network, Y-shaped structure definitely has a significant impact on the performance of the whole network. In this paper, the analytical relationship between Y-shaped microchannel geometry and its capillary flow time is established through theoretical analysis with mass continuity equation and Navier-Stokes (N-S) equations. The result reveals that the capillary flow time increases with the increase of the topology length and bifurcation angle of the Y-shaped microchannel, but decreases with the increase of the channel width.

The numerical simulation of heat transfer during a hybrid laser–MIG welding using equivalent heat source approach

The present study is dedicated to the numerical simulation of an industrial case of hybrid laser–MIG welding of high thickness duplex steel UR2507Cu with Y-shaped chamfer geometry. It consists in simulation of heat transfer phenomena using heat equivalent source approach and implementing in finite element software COMSOL Multiphysics. A numerical exploratory designs method is used to identify the heat sources parameters in order to obtain a minimal required difference between the numerical results and the experiment which are the shape of the welded zone and the temperature evolution in different locations. The obtained results were found in good correspondence with experiment, both for melted zone shape and thermal history.

Synthesis, crystal structures, spectroscopic and thermal properties of silver(I) saccharinate complexes with N-donor ligands

The synthesis, spectroscopic and thermal properties and X-ray structures of four silver(I) saccharinate complexes with N-donor ligands, [Ag(sac)(edmen)] (1), [Ag(sac)(teten)] (2), [Ag2(sac)2(o-bix)2] (3) and [Ag(sac)(dpa)] (4) (edmen=N-ethyl-N′,N′-dimethylethylenediamine, teten=N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine, o-bix=1,2-bis(imidazole-1-ylmethyl)benzene and dpa=2,2′-dipyridylamine) are described. In complex 1, the Ag(I) ion is coordinated by two N atoms from edmen and one N atom from sac ligand, forming a slightly distorted Y-shaped AgN3 arrangement. In complex 2, the Ag(I) is four coordinated by N-bonded sac and tridentate teten ligands, exhibiting a seesaw AgN3O geometry. A crystallographically independent Ag(I) ion in 3 is surrounded with a T-shaped geometry by two N atoms from o-bix ligand and one N atom from one sac ligand, and the Ag⋯Ag separation is 3.338Å. In complex 4, the Ag1 ion is coordinated by three nitrogen atoms from sac and dpa ligands to form a distorted Y-shaped geometry. The dpa ligand behaves as a bidentate ligand, forming a six-membered chelate ring, while the sac ligand is N-coordinated. The most striking feature of complexes 1 and 2 is the presence of both intra- and intermolecular C–H⋯Ag hydrogen-bonding interactions. Crystal packing of complexes is achieved by the hydrogen bonds, intra- and/or intermolecular C–H⋯π, weak π⋯π and Ag⋯π interactions to generate a three-dimensional supramolecular network. The photoluminescence spectrum shows that 4 displays a red-shift emission in the solid state at room temperature.

Structural variation in gold(I)-chelate systems: Synthesis of an asymmetrically bridged β-diketiminato complex of gold

The reaction of the potassium diketiminate K[RNC(CF3)CH(CF3)CNR)], where R=3,5-C6H3Me2, with PPh3AuCl afford the complex [RNC(CF3)CH(CF3)CNR)AuPPh3]. Unlike gold(I) diketiminates without backbone-CF3 substituents, the complex is thermally stable in the solid state and in solution. The crystal structure confirms that, unlike previous examples of Au(I) ketiminates, this complex possesses a three-coordinate metal centre with a distorted Y-shaped coordination geometry.

Experimental investigation of behavior of steel frames with y-shaped concentric bracing

Concentric bracings composed of three members arranged in y-shaped geometry have been traditionally used to provide openings in braced bays. However, using common single gusset plates in y-braced frames leads to single curvature flexure and out of plane buckling of braces accompanied by low hysteretic energy dissipation. In order to explore and improve the behavior of y-braced frames, a research program including experimental tests was conducted at BHRC 1 1 Building and Housing Research Center, Iran. structural engineering laboratory. Specimens presented in this paper include four full-scale frames with y-bracings of different geometries and cross sections. Quasi-static cyclic loading was increasingly applied until yielding and failure occurred in the specimens. The results show that out-of-plane buckling with single curvature in braces can be replaced by in-plane, double curvature buckling through appropriate detailing of cross sections and connections. These sections have larger radius of gyration for out of plane buckling of bracing members. Hysteretic energy dissipation and damping of y-bracing are increased due to inelastic flexural deformation of brace members. Energy dissipation capacity of y-braced frames with new details is comparable with the traditional X bracing. Based on these findings, two-bay y-braced frames were designed to carry the same lateral load as X-braced frames. The seismic performance of these frames was compared using nonlinear static procedures and found to be similar.

Growth of phreatomagmatic explosion craters: A model inferred from Suoana crater in Miyakejima Volcano, Japan

A subvertical cross section of a maar–diatreme volcano is exposed in the wall of the A.D. 2000 caldera on Miyakejima Volcano. The maar, Suoana, is one of the lateral vents of this volcano and it was inferred to be formed in the 7th century. The subvertical wall of the A.D. 2000 caldera truncated the Suoana maar crater at its center revealing the near comlete cross section of this small maar–diatreme volcano. Exposed in the cross section are a 400 m wide maar crater, an associated tuff ring with a maximum thickness of 20 m, a diatreme extending vertically to a depth of about 220 m from the floor of the maar crater, and a feeder dike connected to the base of the diatreme. The depth of the diatreme structure is about 260 m from the original ground surface. The outline of the diatreme resembles an upward-opening funnel with an almost vertical wall below 560 m asl and an upward flaring wall above 560 m asl. Coarse grained volcanic breccia fills the diatreme, the deposits of which can be divided into 6 units based on lithological and structural characteristics. The upper half of the diatreme is filled with landslide deposits, mainly derived from the surrounding crater wall. The bottom of the diatreme is occupied by massive explosion breccia. Some coherent blocks were detached from the wall of the diatreme and preserved in the diatreme fill. The Y-shaped cross-sectional geometry of the Suoana diatreme is the result of a combination of an underground subsidence in the lower part of the diatreme and the surface landslide in its upper part. The inwardly-inclined stratification of pyroclastic rock units and development of many small faults in the diatreme-filling breccia indicate successive collapse and deformation of these materials within the diatreme during the eruption. The upper part of the diatreme was formed by the landslides of the crater wall induced by the subsidence of the crater floor. Discharge of tephra from the bottom of the diatreme caused infill subsidence, which induced sliding of the inner wall of the crater. As a result, the topographic diameter of the crater became much larger than that of the diatreme itself. The tephra ring surrounding the crater consists mainly of pyroclastic fall deposits.

Three-dimensional CFD modelling of a continuous immunomagnetophoretic cell capture in BioMEMs

Separation of rare cells from blood stream using paramagnetic/superparamagnetic beads in microfluidic device has gained importance in recent years for early diagnosis of several critical diseases. However, the performance of immunomagnetophoretic cell sorters (ICS) crucially depends on their design and operational conditions. Here, we present a three-dimensional CFD model based on the Navier–Stokes equations governing the fluid dynamics and continuum descriptions for the cell, bead and cell–bead complexes for a continuous ICS. The spatial-temporal evolution of the concentration fields are governed by convection–diffusion equations for non-magnetic cells and Nernst–Planck type equations for beads and cell–bead(s) complexes. The attachment rates between cells, cell–bead(s) complexes and beads are deduced from the collision probabilities which are derived by means of classical scattering theory. The CFD model is used to investigate the performance of a generic continuous cell separation system. Since the cells are larger in diameter, more than one bead can get attached to the cells. Multiple beads binding to the cell has been considered in this study, which has not been reported in literature till date. Exemplarily, we investigate the performance of Y-shaped geometry used for contacting of cells and beads.

Poly[[aquabis(μ3-isonicotinato-κ3O:O′:N)tris(μ2-isonicotinato-κ3O,O′:N)(nitrato-κO)bis(μ4-oxalato-κ6O1,O2:O2:O1′,O2′:O1′)dierbium(III)tetrasilver(I)] tetrahydrate

In the title coordination polymer, {[Ag4Er2(C6H4NO2)5(C2O4)2(NO3)(H2O)]·4H2O}n, each ErIII atom is coordinated in a bicapped trigonal–prismatic coordination geometry by three O atoms from two isonicotinate (IN) ligands, four O atoms from two oxalate ligands and one O atom from either a nitrate ion or a water mol­ecule, both of which are half-occupied over the same site. One AgI atom has a Y-shaped geometry defined by one N atom from one IN ligand, one O atom from another IN ligand and one O atom from an oxalate ligand. The other AgI atom is coordinated by two IN ligands and one O atom from an oxalate ligand. One of the IN ligands is disordered over an inversion center and forms a bridge between two centrosymmetric AgI ions. Due to the disorder, this IN ligand coordinates to the Ag atom through either the pyridyl N or the carboxyl­ate O atoms. The IN and oxalate ligands link the Er and Ag atoms into a three-dimensional coordination framework. O—H⋯O and C—H⋯O hydrogen bonds are observed in the crystal structure.

Understanding and Predicting Distorted T- versus Y-Geometries for Neutral Chromous Complexes Supported by a Sterically Encumbering β-Diketiminate Ligand

A series of three-coordinate Cr(II) complexes sharing the common molecular fragment "(nacnac)Cr" (nacnac(-) = [ArNC((t)Bu)](2)CH, Ar = 2,6-(i)Pr(2)C(6)H(3)) were prepared via salt metathesis with the dimer [(nacnac)Cr(mu-Cl)](2). Single-crystal X-ray diffraction studies revealed that the complexes (nacnac)Cr(L) (L = CH(2)(t)Bu, CH(3), CH(2)CH(3), SiH{2,4,6-Me(3)C(6)H(2)}(2), O{2,6-(i)Pr(2)C(6)H(3)}, N{CH(3)}(2)) represent a rare class of mononuclear, neutral chromium complexes with a three-coordinate high-spin chromous metal center. Depending on the nature of the third ligand, L(-), these complexes can adopt either distorted T-shaped or Y-shaped coordination geometries. Density functional theory calculations and molecular orbital analyses in combination with a detailed molecular fragment energy decomposition were used to establish an intuitive concept of the key electronic structure patterns that determine the coordination geometry of preference. The frontier orbitals of the (nacnac)Cr(II) fragment direct pi-donating ligands to adopt Y-shaped geometry, whereas ligands that are primarily sigma-donors prefer T-shaped coordination. The relationship between electronics at the metal center and coordination geometry was extended to include the putative neutral three-coordinate high-spin complexes of Sc(II) and Mn(II), which are predicted to both adopt Y-shaped geometry.