Polar Axis Research Articles

Characteristics of wild hazelnut populations in Northeast China and selection of superior provenances.

China possesses a copious and geographically diverse reservoir of hazel (Corylus spp.) resources, albeit scholarly endeavors focusing on the selection and domestication of indigenous wild hazelnut strains remain scant. To develop and utilize high-quality wild hazelnut resources, this study selected eight populations of wild hazelnuts from seven different provenances in Heilongjiang Province, China. Natural hybrid seeds of eight populations were sown in the Chohai Forest Farm in Longjiang County, Heilongjiang Province, in 2018. In April 2020, two-year-old seedlings were used to establish a provenance trial forest, thereby initiating the provenance trial. Growth parameters were measured using electronic calipers, and pollen characteristics were observed under an electron microscope. The trials meticulously explored the trees' flowering biology, growth parameters, and the economic attributes of the produced nuts. Principal component analysis was employed to comprehensively assess differences among the wild hazelnut populations from various provenances, aiming to identify superior wild hazelnut provenances. The results unveiled significant geographical variations among the tested provenances across several facets: the flowering period of male blossoms extended from April 2nd to April 19th, while female flowering occurred within the timeframe of April 2nd to April 22nd. Moreover, pollen grain morphology demonstrated variability, with the polar axis ranging from 14.02 to 17.09 micrometers, the equatorial axis spanning 16.02 to 18.75 micrometers, and the ratio of polar to equatorial axes fluctuating between 0.88 and 0.92. Through correlation analyses, nut length emerged as a pivotal determinant significantly influencing both kernel weight and the hundred-grain weight. A principal component analysis (PCA) further consolidated these findings, selecting the Nehe-originated variegated Corylus heterophylla as the superior provenance based on a comprehensive evaluation of its combined traits. This study constitutes a seminal contribution to the hazelnut breeding endeavor in China, establishing a robust foundation for informed cultivation strategies geared towards optimizing both the yield and the quality of hazelnut resources, thereby advancing the understanding and exploitation of China's wild hazelnut biodiversity.

Deep-Ultraviolet Transparent Nonlinear Optical Phosphates: A New Alternative to Conventional Borates.

Deep ultraviolet (DUV) nonlinear optical (NLO) crystals with balanced performance are crucial for extending laser wavelengths into the DUV region, essential for various laser applications. However, developing ideal DUV crystals is challenging due to stringent requirements: strong second-harmonic generation (SHG) response, short cut-off wavelength, and effective phase-matching behavior. DUV NLO borates, which feature π-conjugated groups, have garnered attention for their higher SHG coefficients compared to phosphates. However, phosphates typically show short UV cut-off edges due to the large HOMO-LUMO gap (approximately 9.6 eV) of the [PO₄] units. To enhance the SHG effect while maintaining DUV transparency in phosphates, several strategies have been proposed: 1) using distorted polymerized P-O groups like isolated C₁-[P₃O₁₀]⁵⁻ and [P₂O₇]⁴⁻; 2) aligning isolated [PO₄]³⁻ tetrahedra along the polar screw axis; 3) introducing additional NLO-active units; and 4) exploring new units derived from [PO₄]³⁻, such as [PO₃F]²⁻ tetrahedra. These strategies have led to the successful development of various non-centrosymmetric phosphates, highlighting their potential as DUV NLO candidates. This review explores the relationship between their crystal structures and DUV NLO performance, and proposes future directions for developing ideal DUV NLO materials.

Composite quadrupole order in ferroic and multiferroic materials

The formalism of composite and intertwined orders has been remarkably successful in discussing the complex phase diagrams of strongly correlated materials and high-$T_c$ superconductors. Here, we propose that composite orders are also realized in ferroelectric and ferromagnetic materials when lattice anisotropy is taken into account. This composite order emerges above the ferroic phase transition, and its type is determined by the easy axis of magnetization or polarization, respectively. In multiferroic materials, where polarization and magnetization are coupled, composites of both orders are possible. This formalism of composite orders naturally accounts for magnetoelectric monopole, toroidal, and quadrupole orders. More broadly, composite orders may explain precursor phenomena in incipient (multi)ferroic materials, arising at temperatures above the ferroic phase transition and potentially contributing to the characterization of currently hidden orders.

The Investigation of Comparative Spore Morphologies of Acrocarpous and Pleurocarpous Two Mosses (Bryophyta)

Bryophyta members in the subkingdom Bryobiotina are distributed in a wide variety of habitats. Mosses are morphologically divided into two large groups: acrocarpous and pleurocarpous. Acrocarpic species have arid character and pleurocarpic species are distributed in more moist regions. The spores of the pleurocarpous Brachythecium salebrosum (Hoffm. ex F. Weber & D. Mohr) Schimp. and the acrocarpous Crossidium squamiferum var. pottioideum (De Not.) Mönk. were examined in comparison in this study. Spore slides were prepared using both Erdtman (acetolysis) and Wodehouse methods and examined under a light microscope (LM). As a result of the analyses, it was found that the spores of C. squamiferum var. pottioideum were oblate in both methods, while the spores of B. salebrosum were suboblate in the acetolysis method and oblate in the Wodehouse method. Spores of both taxa are classified as small spores. Furthermore, the equatorial axis is longer than the polar axis in the spores of both taxa and the thicknesses of the intine layer of the spores are almost identical at 0.50 µm (B. salebrosum) and 0.53 µm (C. squamiferum var. pottioideum). In addition, the thickness of the sclerine of B. salebrosum spores was about 0.70 µm in both methods, while it was 0.56 µm in acetolysed spores of C. squamiferum var. pottioideum and 0.78 µm in Wodehouse treated spores. Both taxa have monolete and trilete spores. On the other hand, SEM examinations revealed that B. salebrosum has gemmate ornamentation, while C. squamiferum var. pottioideum has verrucate ornamentation. The findings obtained as a result of the studies helped to reveal the differences between the spores of taxa in different morphological groups and brought a different perspective in their ecological evaluation.

Structural changes during wake-up and polarization switching in a ferroelectric Hf0.5Zr0.5O2 film

Ferroelectric polycrystalline hafnium oxide films hold great promise for the electronics industry, though an understanding of ferroelectricity in this unconventional material is still lacking. Here, by an in situ synchrotron X-ray microdiffraction experiment, we reveal an important role of reversible and irreversible ferroelastic switching in the mechanism of polarization reversal in a 10 nm thick Hf0.5Zr0.5O2 film and in the origin of the so called wake-up effect consisting in a gradual increase in the remanent polarization of as-prepared memory structures. During the wake-up, the oblique polar axis irreversibly rotates in some ferroelectric orthorhombic grains and becomes more vertical on average in the film, which is the mechanism of the increase in measured polarization. This effect originates from the tensile stress emerging in the film during crystallization annealing and its gradual decrease via the rearrangement of the crystal lattice, which is consistent with first-principles calculations. In the woken-up structures, the polar axis also rotates during polarization switching, but reversibly, which means a different crystal structure of Hf0.5Zr0.5O2 in the upward and downward polarization states and breaking the inversion symmetry. The results provide insight into fundamentals of ferroelectric hafnium oxide and points the way for intelligent material engineering in the field of ferroelectrics-based devices.

Spatial distribution of gamma rays produced by axially symmetric polarized and optical vortex lasers

The polarization properties and spatial distribution of electromagnetic radiation emitted from a high-energy electron can be calculated using the Lienard-Wiechert potentials. These properties are characterized by changes in electron orbitals. In Thomson or Compton scattering by relativistic electrons, which involves the interaction between electrons and a laser, the transverse motion of the electrons is induced by the laser's electric field. The polarization characteristics and spatial distribution of emitted radiation in linearly and circularly polarized laser fields have been extensively studied. In this paper, using a CdTe image sensor, the spatial distribution of MeV gamma rays generated by a 90-degree collision between a 750 MeV electron beam and an axially symmetric polarized laser was measured. The axially symmetric polarized laser, which includes radially and azimuthally polarized components, was created from a linearly polarized laser using a spatially variant retarder known as an s-waveplate. The spatial distribution of gamma rays exhibited a peak at the center, similar to linearly and circularly polarized gamma rays, but differed in overall contour from both. This result suggested that axially symmetric polarized lasers generated gamma rays with different polarization states. Moreover, the contour was observed to change with the polarization axis of the axially symmetric polarized laser, likely owing to the nonuniform distribution of the laser's polarization intensity. Additionally, the spatial distribution of gamma rays produced by circularly polarized optical vortex lasers was measured, showing that their contours corresponded to those of nonvortex circularly polarized lasers. Published by the American Physical Society 2024

Radiolarians from Cambrian Series 2 Niujiaohe Formation in southern Jiangxi, South China

The origin and early evolution of radiolarian fossils have always provoked great interest among paleontologists. Yet, little is known about the earliest morphological and evolutionary characteristics of radiolarians largely due to the lack of documentation of early Cambrian radiolarian fossils. Herein, we conduct a thorough examination of the basinal Niujiaohe Formation in Chongyi County of southern Jiangxi and report two types of radiolarians: a large number of spherical radiolarians and a minor occurrence of ellipsoidal radiolarian fossils with bipolar rodded spines. The lengths of the spines on ellipsoid radiolarian fossils vary, and typically, the main spines are slightly offset from the polar axis, resulting in an asymmetrical appearance in some specimens. Through systematic taxonomic examination, this radiolarian fossil form is tentatively identified as Beothuka sp. of the spherical polycystine group. The genus Beothuka is commonly found in the Early Ordovician and has not yet been reported in the early Cambrian. Combined with previous reports, four species of radiolarians in three genera are identified from the Niujiaohe Formation in South China, including Paraantygopora porosa, Paraantygopora sp., spherical radiolarian, and Beothuka sp. Overall, the radiolarian fossils in the Niujiaohe Formation are characterized by low diversity and small size, in contrast to the relatively more diverse fauna found in the contemporary shallow-water Shuijingtuo Formation. Therefore, we speculate that radiolarians may have initially originated in shallow water areas and gradually expanded to deep water. This study further enriches the fossil record of the Cambrian Series 2 radiolarians. Combined with relevant data from South China, the radiolarian fauna began to exhibit diversity and complex morphology, indicating the presence of various, advanced spherical-skeletons in early radiolarians, and radiolarians from the early Cambrian appeared to display multiple evolutionary trends.

Optical Möbius strips in isotropic random non-paraxial light

Abstract The statistics of Möbius strips with various topologies, formed by the axes of polarization ellipses as they are traced along a closed circular contour of small size passing through the center of a solitary circular polarization singularity line (C-line), have been investigated both analytically and numerically in a random isotropic electromagnetic field. Found are the analytical expressions for the joint probability density function of the differential characteristics of the random isotropic electromagnetic field, which allow for the determination of the topological properties of diagrams of polarization ellipses and the normal vectors to them, as well as the optical strips that arise in the space around C-lines.

Peptide programming of supramolecular vinylidene fluoride ferroelectric phases.

Ferroelectric structures have spontaneous macroscopic polarization that can be inverted using external electric fields and have potential applications including information storage, energy transduction, ultralow-power nanoelectronics1,2 and biomedical devices3. These functions would benefit from nanoscale control of ferroelectric structure, the ability to switch polarization with lower applied fields (low coercive field) and biocompatibility. Soft ferroelectrics based on poly(vinylidene fluoride) (PVDF)4-6 have a thermodynamically unstable ferroelectric phase in the homopolymer, complex semi-crystalline structures, and high coercive fields. Here we report on ferroelectric materials formed by water-soluble molecules containing only six VDF repeating units covalently conjugated to a tetrapeptide, with the propensity to assemble into the β-sheet structures that are ubiquitous in proteins. This led to the discovery of ribbon-shaped ferroelectric supramolecular assemblies that are thermodynamically stable with their long axes parallel to both the preferred hydrogen-bonding direction of β-sheets and the bistable polar axes of VDF hexamers. Relative to a commonly used ferroelectric copolymer, the biomolecular assemblies exhibit a coercive field that is two orders of magnitude lower, as the result of supramolecular dynamics, and a similar level of remnant polarization, despite having a peptide content of 49 wt%. Furthermore, the Curie temperature of the assemblies is about 40 °C higher than that of a copolymer containing a similar amount of VDF. This supramolecular system was created using a biologically inspired strategy that is attractive in terms of sustainability and that could lead to new functions for soft ferroelectrics.

Cellular and molecular mechanisms of asymmetric stem cell division in tissue homeostasis.

The asymmetric cell division determines cell diversity and distinct sibling cell fates by mechanisms linked to mitosis. Many adult stem cells divide asymmetrically to balance self-renewal and differentiation. The process of asymmetric cell division involves an axis of polarity and, second, the localization of cell fate determinants at the cell poles. Asymmetric division of stem cells is achieved by intrinsic and extrinsic fate determinants such as signaling molecules, epigenetics factors, molecules regulating gene expression, and polarized organelles. At least some stem cells perform asymmetric and symmetric cell divisions during development. Asymmetric division ensures that the number of stem cells remains constant throughout life. The asymmetric division of stem cells plays an important role in biological events such as embryogenesis, tissue regeneration and carcinogenesis. This review summarizes recent advances in the regulation of asymmetric stem cell division in model organisms.

Modelling uncertainty in P-wave arrival-times retrieved from DAS data: case-studies from 15 fibre optic cables

SUMMARY Distributed acoustic sensing (DAS) technology enables the detection of waves generated by seismic events, generally as uniaxial strain/strain rate time-series observed for dense, subsequent, portions of a Fibre Optic Cable (FOC). Despite the advantages in measurement density, data quality is often affected by uniaxial signal polarization, site effects and cable coupling, beyond the physical energy decay with distance. To better understand the relative importance of these factors for data inversion, we attempt a first modelling of noise patterns affecting DAS arrival times for a set of seismic events. The focus is on assessing the impact of noise statistics, together with the geometry of the problem, on epicentral location uncertainties. For this goal, we consider 15 ‘real-world’ cases of DAS arrays with different geometry, each associated with a seismic event of known location. We compute synthetic P-wave arrival times and contaminate them with four statistical distributions of the noise. We also estimate P-wave arrival times on real waveforms using a standard seismological picker. Eventually, these five data sets are inverted using a Markov chain Monte Carlo method, which offers the evaluation of the relative event location differences in terms of posterior probability density (PPD). Results highlight how cable geometry influences the shape, extent and directionality of the PPDs. However, synthetic tests demonstrate how noise assumptions on arrival times often have important effects on location uncertainties. Moreover, for half of the analysed case studies, the observed and synthetic locations are more similar when considering noise sources that are independent of the geometrical characteristics of the arrays. Thus, the results indicate that axial polarization, site conditions and cable coupling, beyond other intrinsic features (e.g. optical noise), are likely responsible for the complex distribution of DAS arrival times. Overall, the noise sensitivity of DAS suggests caution when applying geometry-only-based approaches for the a priori evaluation of novel monitoring systems.

Oriented Crystal Polarization Tuning Bulk Charge and Single-Site Chemical State for Exceptional Hydrogen Photo-Production.

Rapid bulk charge recombination and mediocre surface catalytic sites harshly restrict the photocatalytic activities. Herein, the aforementioned concerns are well addressed by coupling macroscopic spontaneous polarization and atomic-site engineering of CdS single-crystal nanorods for superb H2 photo-production. The oriented growth of CdS nanorods along the polar axis, vectorially superimposing substantial polar units with orderly arrangement, renders a strong polarization electric field (20.1 times enhancement), which boosts bulk charge separation with an efficiency up to 72.4% (80.4-fold). Remarkably, polarization electric field alters the chemical state of Pt single sites by orderly reducing the binding energy of Pt atom with stepwise polarization enhancement of CdS substrate, which increases the onsite electron density of Pt from 10.232 to 10.261e- and *H key intermediates, providing preponderant Volmer-Tafel/Volmer-Heyrovsky reaction pathways with significantly decreased energy barriers for H2 production. Thus, highly polarized CdS nanorods with atomically dispersed Pt sites perform an outstanding H2 space-time yield of 118.5mmol g-1 h-1 and apparent quantum efficiency of 57.7% at λ = 420nm, and a record-high H2 turnover frequency of 57798.4 h-1, being one of the best catalysts for photocatalytic H2 evolution. This work highlights the function of polarization in manipulating charge separation and catalytic reaction.

Ultra-wideband and high-efficiency polarization rotator based on liquid crystals

We propose a novel design of an asymmetrically anchored negative liquid crystal (LC) cell capable of linearly rotating the polarization axis of broadband light, with the rotation angle controlled by voltage. Unlike conventional LC cells that require polarization filters or retarders, our LC cell can directly modulate the polarization state of light without any additional components. The LC cell exhibits high polarization rotation efficiency over a wide wavelength range (200 nm to 2000nm), superior to the existing polarization modulators. We validate our design through theoretical calculations and numerical simulations, proving that a degree of linear polarization of over 0.95 can be achieved in the UV, visible, and NIR regions. Our design can be applied in optical communications, biological imaging, and spectroscopic technologies.

An orbital angular momentum assisted extended reach CPDM-Ro-FSO system under diverse weather instabilities

Abstract An orbital angular momentum (OAM)-assisted 640 Gbps circular polarization division multiplexing (CPDM) based extended reach radio over free space optical (Ro-FSO) system is presented in this research paper. For the data modulation, a highly spectrum efficient 256-quadrature amplitude modulation (256-QAM) is employed and proposed system is investigated in the presence of diverse weather instabilities such as clear weather, haze, and rain. CPDM is a highly advanced method that dominates linear PDM (LPDM) since it does not need polarization axis alignment and scattering light is distributed uniformly. For the implementation of OAM, the same wavelength channel has been assigned Laguerre–Gaussian (LG) modes such as LG0,0 and LG13,0, respectively. The detailed performance comparisons of OAM beams and right/left circular polarization states (R/L CPS) are conducted at varied Ro-FSO link lengths using digital signal processing (DSP)-enabled receivers in terms of quality factor (Q-factor) and bit error rate (BER). The proposed system is competent to cover a 45 km distance under clear weather carrying an 80 GHz RF signal, 10 km under haze, and 4 km under the rain with the highest Q factor for all weathers at LG0,0 right circular polarization state (RCPS). Further, a mathematical modelling of the proposed system is presented, and pointing errors are investigated in Optisystem version 20. Results revealed that higher symbol error rates (SERs) can be discernible at higher misalignments between the FSO transmitter and receiver. After conducting a comprehensive literature survey, it is observed that the presented system has covered the maximum distance at 640 Gbps capacity using OAM and CPDM.

Using both faces of polar semiconductor wafers for functional devices

Unlike non-polar semiconductors such as silicon, the broken inversion symmetry of the wide-bandgap semiconductor gallium nitride (GaN) leads to a large electronic polarization along a unique crystal axis1. This makes the two surfaces of the semiconductor wafer perpendicular to the polar axis substantially different in their physical and chemical properties2. In the past three decades, the cation (gallium) face of GaN has been used for photonic devices such as light-emitting diodes (LEDs) and lasers3–5. Although the cation face has also been predominantly used for electronic devices, the anion (nitrogen) face has recently shown promise for high-electron-mobility transistors (HEMTs) owing to favourable polarization discontinuities6. In this work, we introduce dualtronics, showing that it is possible to make photonic devices on the cation face and electronic devices on the anion face of the same semiconductor wafer. This opens the possibility for making use of both faces of polar semiconductors in a single structure, in which electronic, photonic and acoustic properties can be implemented on opposite faces of the same wafer, markedly enhancing the functional capabilities of this revolutionary semiconductor family.

Near-Coherent Quantum Emitters in Hexagonal Boron Nitride with Discrete Polarization Axes

Near-Coherent Quantum Emitters in Hexagonal Boron Nitride with Discrete Polarization Axes

Organic THz Crystals Based on Off‐Diagonal Optical Nonlinearity with Optimal In‐Plane Polar Axis

AbstractHighly efficient off‐diagonal THz generators based on novel organic nonlinear optical single crystals with optimal polar axis orientation in the as‐grown crystal morphology are introduced. The newly developed fluorinated and non‐fluorinated cationic chromophores exhibit a non‐centrosymmetric crystal structure with P21 space group symmetry in the crystalline phase. In particular, PB5FB‐T (5‐fluoro‐2‐(4‐(2‐(hydroxymethyl)pyrrolidin‐1‐yl)styryl)‐3‐methylbenzothiazol‐3‐ium 4‐methylbenzenesulfonate) crystals have an in‐plane polar axis, along with a top‐level off‐diagonal component of the nonresonant effective first hyperpolarizability of ≈100 × 10−30 esu. This stands in stark contrast to previously reported organic THz crystals, which either show a small off‐diagonal optical nonlinearity with an in‐plane polar axis or a large off‐diagonal optical nonlinearity with an almost out‐of‐plane polar axis. Employing an off‐diagonal THz generation configuration, PB5FB‐T crystals generate a THz electric field approximately four times higher than previously reported benchmark analogous crystals with a polar axis nearly out‐of‐plane. Moreover, PB5FB‐T crystals yield smooth THz spectral shapes without significant absorption dimples up to 6 THz when utilizing 130‐fs pump pulses at the wavelength of 1300 nm.

Taxonomic insights into medicinal plants pollen, using advanced microscopy techniques, from the Western Ghats, India

Pollen morphological study on 18 medicinal plants from the Western Ghats (India) was carried out using light microscopy (LM), confocal laser scanning microscopy (CLSM) and field emission scanning electron microscopy (FESEM) techniques. The principal aim was to obtain high-resolution three-dimensional images and ultra-structure of the pollen grains of the studied taxa. The palyno-morphological characters, such as polar axis, equatorial diameter, P/E ratio, pollen shape, aperture type and number, exine thickness and surface ornamentation will be useful in the identification and taxonomic classification of the studied medicinal plants. Statistical analysis reveals grouping of the taxa in three different clusters and also isolated presence of taxa on the principal component analysis (PCA) biplot, irrespective of their families, showing similarities and/or variations among the studied taxa, belonging to the same and/or different families. The present study has taxonomic significance, providing high taxonomic resolution (identification of the taxa up to species level), and further aid in the identification and delimitation of the 18 studied plants.

A new motile animal with implications for the evolution of axial polarity from the Ediacaran of South Australia.

Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One approach to recognize such early animals is to instead focus on characteristics widespread in animals today, for example multicellularity, motility, and axial polarity. Here, we describe a new taxon, Quaestio simpsonorum gen. et sp. nov. from the Ediacaran of South Australia. Quaestio is reconstructed with a thin external membrane connecting more resilient tissues with anterior-posterior polarity, left-right asymmetry and tentative evidence for dorsoventral differentiation. Associated trace fossils indicate an epibenthic and motile lifestyle. Our results suggest that Quaestio was a motile eumetazoan with a body plan not previously recognized in the Ediacaran, including definitive evidence of chirality. This organization, combined with previous evidence for axial patterning in a variety of other Ediacara taxa, demonstrates that metazoan body plans were well established in the Precambrian.

Visualizing plasmons and ultrafast kinetic instabilities in laser-driven solids using X-ray scattering

Ultra-intense lasers that ionize atoms and accelerate electrons in solids to near the speed of light can lead to kinetic instabilities that alter the laser absorption and subsequent electron transport, isochoric heating, and ion acceleration. These instabilities can be difficult to characterize, but X-ray scattering at keV photon energies allows for their visualization with femtosecond temporal resolution on the few nanometer mesoscale. Here, we perform such experiment on laser-driven flat silicon membranes that shows the development of structure with a dominant scale of 60 nm in the plane of the laser axis and laser polarization, and 95 nm in the vertical direction with a growth rate faster than 0.1 fs−1. Combining the XFEL experiments with simulations provides a complete picture of the structural evolution of ultra-fast laser-induced plasma density development, indicating the excitation of plasmons and a filamentation instability. Particle-in-cell simulations confirm that these signals are due to an oblique two-stream filamentation instability. These findings provide new insight into ultra-fast instability and heating processes in solids under extreme conditions at the nanometer level with possible implications for laser particle acceleration, inertial confinement fusion, and laboratory astrophysics.