Polar Axis Research Articles

Sphaeromyxa cornuti n. sp., a New Species of Myxosporean Infecting the Gallbladder of the Moorish Idol, Zanclus cornutus (Linnaeus, 1758) from Lakshadweep Waters.

The present study describes a new species of myxosporean, Sphaeromyxa cornuti n. sp. infecting the gallbladder of the Moorish idol, Zanclus cornutus (Linnaeus 1758) collected from Lakshadweep waters of the Arabian Sea. Fish were collected using traps and cages. The morphology of mature spores recovered from the gallbladder of Z. cornutus was studied under Nomarski Differential Interference Contrast (DIC) optics. The molecular and phylogenetic analyses were based on SSU rDNA. Sphaeromyxa cornuti n. sp. is characterized by arcuate myxospores with tapering extremities and round ends in valvular, and slightly sigmoid in sutural views (19.2-24.7 µm × 4.1-5.7µm). The two polar capsules are unequally elongate-ovoid in shape and positioned at opposite ends of the spore (6.2-9.7µm × 1.7-2.6µm). Each encloses an irregularly folded, ribbon-like polar tubule, which is oriented parallel to polar capsule axis. In molecular and phylogenetic analyses, the present myxosporean revealed significant differences with related forms and clustered together with S. hellandi within the 'incurvata' group of the Sphaeromyxa clade with high nodal support. Morphological, morphometric, molecular and phylogenetic differences between our material and previously described species of Sphaeromyxa, along with host and geographic variations indicate that the present myxosporean is unique and the name Sphaeromyxa cornuti n. sp. is proposed. This forms the first report of a myxosporean parasite-infecting Z. cornutus.

Hydrothermal single crystal growth and structural investigation of the stuffed tridymite family as NLO materials

The structures, crystal growth and preliminary NLO properties of a broad class of compounds known as the stuffed tridymites are investigated. The stuffed tridymites of the formula ABC O 4 , where A are the alkali metal ions and B and C are Group 13 and 14 metal ions, respectively, form an extensive series of structures, all of which are based on symmetry breaking of the parent tridymite (SiO 2 ) structure. In all cases the alkali ion resides in channels running parallel to the c- axis formed from six-membered rings of tetrahedra of the metal ions. A large array of structures can be formed though combinations of ordering of the B / C sites, staggered and eclipsed tetrahedra, up/down orientations of the tetrahedra relative to the c -axis, and distortions of the six-membered rings. These symmetry breaking steps can be mixed and matched to form many different structures, and nearly all are in polar acentric space groups. The primary cause of centrosymmetric crystal formation is disorder of the B / C sites. When the sites are well ordered most of the structures are acentric with polar axes. High quality single crystals of most products can be grown using a high pressure hydrothermal method. Preliminary NLO experiments indicate that the compounds are acentric, but have low NLO conversions, which is expected due to the low polarizability of the building blocks. The extremely high percentage of polar acentric structure types, and the ability to correlate the structures to systematic variations of the very large and flexible tridymite structural class, suggests that this can serve as a starting point for designing crystals with many other useful physical properties. • Stuffed tridymites of various compositions were synthesized hydrothermally. • Structural factors affecting symmetry reduction from parent tridymite were identified. • The family exhibits a high percentage of noncentrosymmetric structures. • Powder NLO data was measured on stuffed tridymites.

ORGANIC FERTILIZER AND NATURAL ZEOLITE EFFECTS ON MORPHOMETRIC TRAITS OF BRASSICA NAPUS L. POLLEN GRAINS

Morphological characteristics of Brassica napus pollen (polar axis, equatorial diameter, shape index, pattern of perforation of exines, and perimeter of perforation zones) were investigated by using scanning electron microscopy JEOL JSM-6390. The B. napus seeds were grown under various agroecological conditions, i.e., mineral fertilizer (NPK 60:60:60 t ha-1) separately and together with zeolite, chicken droppings (10 t ha-1) separately and together with zeolite (5 t ha-1), and control (without fertilizers) from 2018 to 2020 at the Bunin Yelets State University, Yelets, Russia. It was found that pollen grains of B. napus had an oblong-ellipsoid shape. In the polar view, the pollen grains were circular with straight sides, though in the equatorial view, elliptical. For the polar axis of the pollen grains in fertilizer application treatments, the minimum values ranged from 24.59 to 27.76 µm, whereas the maximum readings were 40.13 to 42.12 µm compared with control (21.56 µm, 41.52 µm). The coefficient of variation for fertilizer applications ranged from 8.86% to 14.10% compared with control (14.85%) for the polar axis. For the equatorial axis of the pollen grains, the minimum values varied from 11.61 to 15.63 µm, whereas the range for the maximum values was 19.74 to 23.96 µm compared with the control (13.63 µm, 21.88 µm). For the equatorial axis among the fertilizer applications, the coefficient of variation varied from 8.47% to 12.01% compared with the control (18.35%). For the perimeter of the exine perforation of the pollen grains, the minimum values ranged from 1.68 to 1.95 µm, whereas the maximum values varied from 4.34 to 7.12 µm compared with the control (1.34 µm, 5.68 µm). The coefficient of variation varied from 24.48% to 33.19% compared with the control (34.78%) for the perimeter of exine perforation. The shape index of the pollen grains of the B. napus varied from 1.96 to 2.07 µm (correct unit of measure?) compared with the control (2.03 µm). Overall, with the use of organic fertilizers and zeolite, the morphometric parameters of pollen grains were significantly enhanced.

Ultrafast polarization-tunable monochromatic extreme ultraviolet source at high-repetition-rate

We report on the development of a high-order harmonic generation (HHG)-based ultrafast high-repetition-rate (250 kHz) monochromatic extreme ultraviolet (21.6 eV) source with polarization tunability, specifically designed for multi-modal dichroism in time- and angle-resolved photoemission spectroscopy. Driving HHG using an annular beam allows us to spatially separate the high-power 515 nm driving laser from the XUV beamlet while preserving the linear polarization axis angle tunability. This enables controlling the polarization state of the XUV radiation with a fixed all-reflective phase-shifter. This scheme leads to a source brightness of photons s−1 at 21.6 eV (up to photons s−1 on target) with ellipticities as high as 90%.

P-190 The first cleavage plane in human embryos is dictated by the topology of pronuclei, not by the polar body position

Abstract Study question Is the first cleavage plane pre-determined in human embryos? Summary answer Unlike in mice, the human zygotes tend to divide at the right angle to the longitudinal pronuclear axis, irrespective of polar body position. What is known already In lower species, the orientation of the first cleavage plane defines the development of individual blastomeres and the three-dimensional (3D) body plan. The existence of embryonic pre-patterning in mammals remains controversial. Mouse studies suggested that the juxtaposed pronuclei (PN) are aligned with the polar body (PB) and cleavage furrow bisects the zygote along the polar axis thus ensuring symmetrical distribution of maternal resources to arising blastomeres. However, whether the same spatial control applies to humans is unclear. Study design, size, duration Retrospective observational analysis of high-resolution footage from 300 human embryos that gave rise to live births after a single embryo transfer. Participants/materials, setting, methods Embryo monitoring has been performed by the GERI time-lapse incubator. Image acquisition of individual embryo development lasted 6 days, starting within 10 minutes after intracytoplasmic sperm injection (ICSI). Transmitted light images have been automatically captured in 5-minute intervals and 11 focal planes covering the whole embryo volume. Analysis of 3D image data was performed at the time frame corresponding to the onset of the first mitosis. Main results and the role of chance The systematic analysis of the zygotic division pattern showed that the PN axis (defined by apposed pronuclei) was not stereotypically aligned with the animal-vegetal (AV) axis (with animal pole defined by the PB). Instead, PN/AV arrangement categories were equally represented in our cohort (PN/AV angle 0-30° - 34.7% vs. 30-60° - 36.0% and 60-90° - 29.3%; chi-square test p=.91351). Remarkably, we observed that the direction of the first cleavage was preferentially perpendicular to the PN axis (65.3%), while only 2.7% of embryos divided along the longitudinal PN axis. The remaining 32% embryos showed intermediated phenotype with cleavage plane/PN axis angle 30-60o. The results of this human embryo analysis contrast with the previous reports from mice. We hypothesize that this discrepancy might be attributed to the difference in centrosome inheritance and configuration of the zygotic spindle apparatus. Limitations, reasons for caution All analyzed embryos were produced by ICSI. Deposition of spermatozoa might affect the pronuclei positioning. Nevertheless, preliminary data from conventional IVF cycles are in agreement with the ICSI group results. Wider implications of the findings Our observations challenge the textbook view of the first division’s geometry, which has been derived from experiments in mice. The analysis of clinical time-lapse records improves our understanding of symmetry breaking during normal human development and creates scientific ground for evidence-based (de)selection of embryos for infertility treatment. Trial registration number not applicable

Dielectric and pyroelectric properties of AlN single-crystal layers grown by chloride-hydride epitaxy

This work presents the results of a comparative study of dielectric and pyroelectric properties of aluminum nitride (AlN) single-layer and multilayer samples with a thickness of 100 ÷ 200 μm grown in the [0001] direction by chloride-hydride epitaxy. A silicon wafer covered by silicon carbide nanolayer grown by solid-phase substitution (SiC/(111)Si) was used as a substrate for subsequent growth of AlN single crystalline layers. The samples were formed by layer-by-layer growth. It is shown that such method makes it possible to change the orientation of the polar hexagonal axis in AlN single crystals.

Palynomorphological and taxonomical investigations of some Apiaceae taxa from Bilecik, Turkey

The objective of the present study is to investigate pollen morphology and taxonomy of some Apiaceae species in Bilecik, Turkey. The study area is restricted to Vezirhan in the south (Bilecik), Pamukova and Geyve in the north (Sakarya), İznik in the west (Bursa), Gölpazarı in the south-east (Bilecik) and Taraklı in the east (Sakarya). Apiaceae species were collected from the study area by visiting there in all four seasons. In this study, the pollen morphology of 22 taxa belonging to different genera of the Apiaceae family was investigated for the first time in detail using light microscope and scanning electron microscopy (SEM). The pollen is radially symmetrical, isopolar and tricolporate in all examined species. Pollen grains are perprolate, prolate and subprolate with the polar axis ranging from 17.53 µm (Non-acetolysed: N) and 18.28 µm (Acetolysed: A) to 39.71 µm (N) and 39.72 µm (A) and the equatorial axis from 11.77 µm (N) and 12.2 µm (A) to 23.77 µm (N) and 23.54 µm (A). The polar shapes of the studied taxa are triangular. Exine ornamentations of four pollen types have been observed by SEM. Two main groups were revealed in the dendrogram which was constructed by using Average Linkage from the examined data. It was determined that some pollen characteristics of investigated Apiaceae taxa are supporters of the classification of taxa with other taxonomical characteristics. Also, three components of investigated palynological characteristics were identified with principal component analysis. Polar axis (P), equatorial axis (E), the ratio of polar axis to equatorial axis (P/E) (pollen shape) and ornamentation in the polar and equatorial views are determined as the most important palynological characteristics for discrimination of the Apiaceae taxa.

Technical note: Correcting angular dependencies using non-polarized components of Cherenkov light in water during high-energy X-ray irradiation.

Dose distribution measurements of high-energy X-rays from medical linear accelerators (LINAC) in water are important for quality control (QC) of the system. Although Cherenkov-light imaging is a useful method for measuring the high-energy X-ray dose distribution, depth profiles have an underestimated dose at increased depths due to the angular dependency of the Cherenkov light generated in water. In this study, we use a linear polarizer to separate the majority of polarized components from the majority of unpolarized components of Cherenkov-light images in water and then use this information to correct for angular dependencies. A water phantom, a cooled charge-coupled device (CCD) camera, and a polarizer were installed in a black box. Then, the water phantom was irradiated from the upper side with 6 or 10 MV X-rays, and the Cherenkov light generated in water was imaged with the polarizer axis at both parallel and perpendicular orientations to the beam. By using these images from the two orientations relative to the beam, we corrected the angular dependency of the Cherenkov light. By subtracting the images measured with the polarizer perpendicular to the beams from the images measured with the polarizer parallel to the beams, we could obtain images with only the polarized components. Using these images, we could calculate the images with non-polarized components that had similar depth profiles to those calculated with a planning system. The average difference between corrected depth profiles and those calculated with the planning system was less than 1%, while that between uncorrected depth profiles and the planning system was more than 8.3% in depths of water from 20 to 100mm. We conclude that the use of the polarizer has the potential to improve the accuracy of dose distribution in Cherenkov-light imaging of water using high-energy X-rays.

Abstract 673: The EMT activator ZEB1 initiates polarized secretion of pro-tumorigenic effector proteins to drive lung adenocarcinoma progression

Abstract There are few effective therapeutic options for metastatic lung adenocarcinomas (LUADs) that lack actionable mutations in receptor tyrosine kinases, and there is an urgent need to develop a better understanding of the biological basis of LUAD growth and metastasis. Our group has developed mouse models of LUAD metastasis and found that LUAD metastasis is epithelial-to-mesenchymal transition (EMT)-dependent. EMT causes cancer cells to switch their axis of polarity from apical-basal to front-rear, which orients organelles and actinbased cytoskeletal structures in ways that facilitate purposeful cancer cell motility and metastasis. The EMT-activating transcription factor ZEB1 silences microRNAs that target key inhibitors of the polarity axis switch. These data support the general belief that EMT-dependent metastasis is a cell-autonomous process. However, our new findings here show that ZEB1 coordinates the components of secretory trafficking machinery, Rab6A and Rab8A, via silencing miR-148a that target these effectors, to drive polarized secretory trafficking toward the leading edge of LUAD cells, to enhance surface exposure of MMP14 so that triggers ECM degradation, accelerates focal adhesion turnover and promotes cancer cell migration. Moreover, the ZEB1-driven secretory trafficking increases the secretions of cytokines and immunomodulation factors, to generate an immunosuppressive tumor microenvironment, and to promote LUAD metastasis. These findings advance a paradigm in which EMT drives LUAD metastasis through a cell non-autonomous mechanism. The novelty rests in our results that demonstrate a transcriptional governance of polarized vesicular transport, providing the potential to target ZEB1-driven secretory pathways for the purpose of blocking metastasis in LUAD. Citation Format: Guan-Yu Xiao, Xiaochao Tan, Leticia Rodriguez, Xin Liu, Jiang Yu, Mayra Vasquez, Hai Tran, William Russell, Don Gibbons, Jonathan Kurie. The EMT activator ZEB1 initiates polarized secretion of pro-tumorigenic effector proteins to drive lung adenocarcinoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 673.

Pollen Morphology of Lactuca L. (s. lat.) (Cichorieae - Asteraceae) from Hindukush, Western Himalyan and Karakorum Ranges and its taxonomic significance

ABSTRACT Pollen morphology of 15 species of the genus Lactuca L. (s. lat.) of the tribe Cichorieae from the Hindukush, Western Himalayan and Karakorum Ranges has been studied using Light microscope (LM) and Scanning Electron Microscope (SEM). Pollen morphology of six species viz., L. erostrata Bano & Qaiser, L. glaucifolia Boiss., L. persica Boiss., L. crambifolia (Bunge) Boiss., L. chitralensis (Tuisl.) Ghafoor, Qaiser & Roohi Bano and L. picridiformis Boiss., was never studied before. Pollen were found to be isopolar, spheroidal to oblate-spheroidal, elliptic to rarely circular in equatorial view, hexagonal in polar view, trizonocolporate and echinolophate with 15 lacunae. Morphometric analysis of the pollen characters was conducted using Agglomerative cluster analysis with Euclidean distance and Ward’s method to compute the dissimilarity matrix, and a dendogram was prepared. Two pollen-types primarily based on the diameter of polar and equatorial axis of the pollen grain were recognized. Keys to the pollen types, subtypes and to the species are provided. The present palynological findings to a greater extent are in agreement with the results of current phylogenetic studies based on molecular evidences. Moreover, both the pollen types are well correlated with the general morphology of the investigated species of the genus Lactuca L. (s.lat) and provided additional micromorphological characters for the delimitation of the species.

Review of secukinumab-induced adverse events of special interest and its potential pathogenesis.

Although secukinumab has demonstrated high efficacy and favorable safety in moderate-to-severe psoriasis and psoriatic arthritis, patients developing adverse events of special interest (AESI) were reported increasingly in real-world practice. A systematic literature search of the PubMed database was conducted to identify clinical studies or case reports on secukinumab-induced AESI. More than 1077 patients (aged 18-74 years) from 55 studies were reported to have 24 AESI 3 days to 96 weeks after secukinumab treatment. The four most common AESI was inflammatory bowel disease (n > 1000), eczematous drug eruption (n > 30), drug-associated vasculitis (n=8), and drug-induced lupus erythematosus (n=4). Most of these AESI were only mild to moderately severe and resolved after secukinumab discontinuation without or with symptomatic treatment. Secukinumab has the potential to develop a number of AESI by probably dysregulating the different expression of polar T-cell axes (Th1, Th2, Th17, Th22, and/or Treg) and driving various cytokines in some patients. Physicians should be aware of these AESI for timely diagnosis and proper treatment.

Inertial migration of a neutrally buoyant oblate spheroid in three-dimensional square duct poiseuille flows

In this paper, the inertial migration of a single neutrally buoyant oblate spheroid in a square duct is investigated by multiple-relaxation-time lattice Boltzmann method. The spheroid’s aspect ratio AR=a/b=1/2, where a and b are the polar and equatorial radii of the spheroid, respectively, Reynolds number Re=UmH/ν=80 with Um, H and ν being the maximum velocity in the duct without the particle, height of the duct and the kinematic viscosity, respectively, and a blockage ratio 2b/H=0.277 is chosen to study the effects of initial position and initial orientation on the particle’s motion in detail. Our results show that the lateral trajectory and final motion, to some extent, depend on the spheroid’s initial position and orientation. In addition to the general log-rolling (LR) mode, which was previously reported by Lashgari et al. (2017), the spheroid can also exhibit a tumbling (TU) mode, where its polar axis rotates in the central streamwise–wall-normal plane, and an inclined log-rolling (ILR) mode, where it rotates in the diagonal plane with the polar axis being perpendicular to the plane, when its initial position and orientation are well specified. With the Reynolds number increased to 160, the ILR mode disappears while the TU and LR modes persist. If AR decreases to 1/3 while keeping the particle’s volume fixed, all three modes persist at Re=80, and the particle migrates closer to the duct center at the final equilibrium state with decreasing AR for all three different modes.

How to realize a homogeneous dipolar Bose gas in the roton regime

Homogeneous quantum gases open up new possibilities for studying many-body phenomena and have now been realized for a variety of systems. For gases with short-range interactions the way to make the cloud homogeneous is, predictably, to trap it in an ideal (homogeneous) box potential. We show that creating a close to homogeneous dipolar gas in the roton regime, when long-range interactions are important, actually requires trapping particles in soft-walled (inhomogeneous) box-like potentials. In particular, we numerically explore a dipolar gas confined in a pancake trap which is harmonic along the polarization axis and a cylindrically symmetric power-law potential ${r}^{p}$ radially. We find that intermediate $p$'s maximize the proportion of the sample that can be brought close to the critical density required to reach the roton regime, whereas higher $p$'s trigger density oscillations near the wall even when the bulk of the system is not in the roton regime. We characterize how the optimum density distribution depends on the shape of the trapping potential and find it is controlled by the trap wall steepness.

Eurypollinic pollen of the Anacardiaceae differentiates taxa

The pollen morphology of 11 Anacardiaceae species from the Mexican State of Veracruz was studied. Pollen grains were acetolyzed and examined under light and scanning electron microscopy to determine whether their morphological characteristics are useful to differentiate taxa in this family. Photomicrographs were obtained with both types of microscopes and used as the basis for describing the pollen. Pollen descriptions included traits such as shape, the type and number of apertures, exine ornamentation, size of the polar and equatorial axes, and diameter in polar view. Most species have isopolar pollen grains, with tricolpate or tricolporate apertures. Only Pistacia mexicana has pentaporate pollen. Pollen grains exhibit a triradial or radial symmetry in polar view; their shape in equatorial view can be prolate-spheroidal, subprolate, or prolate. The size of axes in equatorial view, diameter in polar view, and the exine ornamentation show distinctive characteristics in each species. However, the most common ornamentation types are microreticulate and microstriate. Ten pollen types were identified based on combinations of traits such as the type and number of apertures, shape in equatorial and polar view, and exine ornamentation. The results confirm that the eurypollinic pollen of Anacardiaceae is valuable for differentiating taxa, highlights the importance of studying pollen morphology and contributes to increasing the knowledge about the pollen morphology of this family in Mexico.

Mechanical strain modulation of domain wall currents across LiNbO3 nanosensors

Recently, studies on low-dimensional conducting domain walls (DWs) in insulating ferroelectrics have opened up new research areas that allow information to be mechanically written and electrically read on the nanoscale. Large strains in thin films can change the polarization gradient across the DW region and thus increasing the DW current significantly. This phenomenon can enable the development of high sensitivity mechanical vibration sensors. In this study, the effects of variable uniaxial strain on the structures of 180° conducting DWs in LiNbO3 (LNO) single-crystal thin films bonded onto Si/SiO2 substrates were investigated. After the creation of antiparallel domains within each LNO nanosensor integrated at the film surface, strain modulation of DW currents was observed through simple mechanical bending of the film. The DW current increases under application of tensile strain along the axis of polarization, but decreases under application of in-plane compression by a factor of approximately 25. Phase field simulations showed the dramatic change in polarization gradients around the DW regions under the increase in tensile strain, which reduced the band gap. Repetitive band-gap narrowing/broadening with change in local electric field intensity under vibrating mechanical forces can periodically modulate both the carrier density and the DW conduction in the sensors. This finding not only provides the new fundamental physics to enrich the ferroelectric theory, but also paves the way to the near-future development of bending actuators, piezolighters, and micro-/nano-manipulators, etc.

Crystallographic orientation dependence of ferroelectric domain walls in antiferroelectric lead zirconate thin films

Domains of antiferroelectric PbZrO3 have been studied. The (111) PbZrO3 has lower field transitions due to the reduction of the angle between the ferroelectric polar axis and the applied electric field. The study of the permittivity reveals also that the (111) PbZrO3 has a higher correlation of dipoles (|Shf| = 0.007) due to the energy gain associated with their orientation. Therefore, the (111) crystallographic orientation is a better choice for obtaining easily switching domain. The dielectric response of the domain walls in the (100) and (111) PbZrO3 are identical because they have the same environment (same grain size and similar defects) and interact in the same way. Only the domain wall density is higher in the (111) PbZrO3 due to its lower crystallographic orientation factor. Different crystallographic directions have more obstacles due to the inhomogeneity of the crystallization and consequently has more nucleation site for domain walls.

Shape of charged domain walls in bidomain lithium tantalate plates with composition gradients

Lithium tantalate LiTaO3 (LT) plates with various composition gradient along the polar axis were produced by partial vapor transport equilibration (VTE) with annealing temperature above phase transition. The proper annealing parameters allow creating a charged domain wall (CDW) in the center of the plate. The CDW morphology depends on the spatial distribution of stoichiometry deviation. The bidomain actuators manufactured from the LT plates after partial VTE procedure possess a linear voltage dependence of the displacement of the free end without any hysteresis. It is shown that increase in CDW roughness leads to a noticeable decrease in the effective piezoelectric coefficient.

Fortunella venosa (Champ. ex Benth.) C. C. Huang and F. hindsii (Champ. ex Benth.) Swingle as Independent Species: Evidence From Morphology and Molecular Systematics and Taxonomic Revision of Fortunella (Rutaceae).

Recently, the systematic status of Fortunella Swingle and its taxonomy has attracted much attention. Flora of China incorporates Fortunella into Citrus Linn. and treats all species of the traditional Fortunella as one species, namely Citrus japonica (Thunb.) Swingle. Furthermore, F. venosa (Champ. ex Benth.) C. C. Huang and F. hindsii (Champ. ex Benth.) Swingle are currently considered as synonyms of C. japonica. In this paper, morphological, palynological, and phylogenetic analyses were used to systematically explore the taxonomic status of traditional Fortunella. The key morphological features that differed among the Fortunella species were the leaf and the petiole hence could be key in its taxonomic classification of the species. Additionally, pollen morphological analysis based on the pollen size, germination grooves, polar, and equatorial axes also supported the separation of the species. The results of the phylogenetic analysis showed that each of the three species clustered separately, hence strongly supporting the conclusion of independent species. In addition, the phylogenetic analysis showed that the two genera clustered closely together hence our results support the incorporation of Fortunella into Citrus. Based on the above, this article has revised the classification of the traditional Fortunella and determined that this genus has three species, namely; F. venosa, F. hindsii, and F. japonica. F. venosa and F. hindsii are placed in the Citrus as separate species, and their species names still use the previous specific epithet. The revised scientific names of the new combinations of F. venosa and F. hindsii are as follows: Citrus venosa (Champ. ex Benth.) K. M. Liu, X. Z. Cai, and G. W. Hu, comb. nov. and Citrus hindsii (Champ. ex Benth.) K. M. Liu, G. W. Hu, and X. Z. Cai, comb. nov. F. venosa is the original species of Fortunella, F. venosa and F. hindsii are both listed as the second-class key protected wild plants in China. Therefore, the establishment of the taxonomic status of F. venosa and F. hindsii not only deepens our understanding, importance, and the complexity of the systematic classification of Fortunella, but is also significant for global biodiversity conservation, genetic resources for breeding purposes, and population genetics.

Pollen Morphological Peculiarities of Selected Mimosoideae Taxa of Hainan Island and Their Taxonomic Relevance

Mimosoideae is one of the taxonomically complex subfamilies of Fabaceae. Several studies have reported the pollen morphology of Mimosoideae taxa and their taxonomic relevance, but no such study was found specifically for Hainan Island in southern China. Therefore, the present study was designed to investigate the selected Mimosoideae taxa and explore the new palynological traits to support and strengthen the systematics of Mimosoideae using multiple microscopic techniques. The polar axis, equatorial diameter of the pollen grains, colpus length and width were measured. The smallest pollen grain size was found in Mimosa pudica (7.8 × 7.75 µm), while the largest pollen size was found in Albizia lebback (87.54 × 77.97 µm). Similarly, significant variation was found in the exine and colpus surface patterns. The subfamily Mimosoideae is considered eurypalynous because of the variation in pollen traits. In addition, variation was also found in the quantitative traits. Comparatively, the pollen features were found to be helpful at the genus and species levels, as well as in the correct identification and discrimination of the taxa. Hence, this study gives a detailed account of the pollen morphologies of certain selected taxa of Mimosoideae collected from different geographical regions on Hainan Island. The pollen morphological traits were proven to have significant taxonomic potential and can be used as additional tools for the correct identification and discrimination of Mimosoideae taxa. These results will provide the basis for further systematic studies.

Chemical Nature of Heterogeneous Electrofreezing of Supercooled Water Revealed on Polar (Pyroelectric) Surfaces.

ConspectusThe ability to control the icing temperature of supercooled water (SCW) is of supreme importance in subfields of pure and applied sciences. The ice freezing of SCW can be influenced heterogeneously by electric effects, a process known as electrofreezing. This effect was first discovered during the 19th century; however, its mechanism is still under debate. In this Account we demonstrate, by capitalizing on the properties of polar crystals, that heterogeneous electrofreezing of SCW is a chemical process influenced by an electric field and specific ions. Polar crystals possess a net dipole moment. In addition, they are pyroelectric, displaying short-lived surface charges at their hemihedral faces at the two poles of the crystals as a result of temperature changes. Accordingly, during cooling or heating, an electric field is created, which is negated by the attraction of compensating charges from the environment. This process had an impact in the following experiments. The icing temperatures of SCW within crevices of polar crystals are higher in comparison to icing temperatures within crevices of nonpolar analogs. The role played by the electric effect was extricated from other effects by the performance of icing experiments on the surfaces of pyroelectric quasi-amorphous SrTiO3. During those studies it was found that on positively charged surfaces the icing temperature of SCW is elevated, whereas on negatively charged surfaces it is reduced. Following investigations discovered that the icing temperature of SCW is impacted by an ionic current created within a hydrated layer on top of hydrophilic faces residing parallel to the polar axes of the crystals. In the absence of such current on analogous hydrophobic surfaces, the pyroelectric effect does not influence the icing temperature of SCW. Those results implied that electrofreezing of SCW is a process influenced by specific compensating ions attracted by the pyroelectric field from the aqueous solution. When freezing experiments are performed in an open atmosphere, bicarbonate and hydronium ions, created by the dissolution of atmospheric CO2 in water, influence the icing temperature. The bicarbonate ions, when attracted by positively charged pyroelectric surfaces, elevate the icing temperature, whereas their counterparts, hydronium ions, when attracted by the negatively charged surfaces reduce the icing temperature. Molecular dynamic simulations suggested that bicarbonate ions, concentrated within the near positively charged interfacial layer, self-assemble with water molecules to create stabilized slightly distorted “ice-like” hexagonal assemblies which mimic the hexagons of the crystals of ice. This occurs by replacing, within those ice-like hexagons, two hydrogen bonds of water by C–O bonds of the HCO3– ion. On the basis of these simulations, it was predicted and experimentally confirmed that other trigonal planar ions such as NO3–, guanidinium+, and the quasi-hexagonal biguanidinium+ ion elevate the icing temperature. These ions were coined as “ice makers”. Other ions including hydronium, Cl–, and SO4–2 interfere with the formation of ice-like assemblies and operate as “ice breakers”. The higher icing temperatures induced within the crevices of the hydrophobic polar crystals in comparison to the nonpolar analogs can be attributed to the proton ordering of the water molecules. In contrast, the icing temperatures on related hydrophilic surfaces are influenced both by compensating charges and by proton ordering.