Low Point Group Research Articles

BenPt (n = 6–8) cluster adsorb water molecule splitting to produce H2 based on density functional theory

The study of catalysts for hydrogen production from water splitting is of great significance for solving the global energy crisis. The lowest energy structures of BenPt (n = 6–8) clusters, the lowest energy structures of BenPt@H2O (n = 6–8) complexes and water molecule splitting to produce H2 of BenPt + H2O (n = 6–8) are investigated based on the density functional theory. According to the computed results, BenPt (n = 6–8) clusters have low point group symmetry in their lowest energy structures. The density of states (DOS) map shows strong interactions between water molecules and clusters in BenPt@H2O (n = 6–8) complexes. The predicted mechanism of the BenPt + H2O (n = 6–8) water molecule splitting to produce H2 shows the maximum Be7Pt + H2O reaction energy (-3.565 eV). Interaction region indication (IRI) plots of the reaction product BenPtO@H2 (n = 6–8) show easy desorption of the H2 molecule from Be7PtO@H2.

Analog Quantum Valley–Hall and Quantum Spin Hall Plasmons in Graphene Metasurfaces with Low Point Group Symmetry

AbstractIn recent years, topological physics of classical waves in artificial crystals has become an emerging field of research. While Dirac cones and valley‐related physics are conventionally studied in these systems with C6v and C3v point‐group symmetries, here analog quantum valley Hall and quantum spin Hall plasmons in graphene metasurfaces with lower point‐group symmetries are explored. First, it is shown that a single‐layer graphene sheet with rectangle holes respecting to the C2v point group symmetry can host a mirror (σv) symmetry‐protected Dirac cone along the X–M edge of the Brillouin zone. Then we demonstrate that introducing further circular holes to the graphene sheet can break the mirror symmetry (i.e., reducing C2v symmetry to C1v) and thus gap out the Dirac cone, which allows us to explore the valley and layer‐pseudospin related topological plasmons in these graphene metasurfaces with low point group symmetry. Valley‐locking unidirectional propagations along the domain–wall interface of a single‐layer graphene metasurface and layer‐pseudospin converter in a double‐layer graphene metasurface are explicitly demonstrated for graphene plasmons in the THz range. This work provides a new design principle for exploring Dirac cones, valley, and pseudospin related physics using much lower point‐group symmetries.

Multi-Biomarker Points and Outcomes in Patients Hospitalized for Heart Failure: Insights From the China PEACE Prospective Heart Failure Study.

ObjectiveTo quantitatively characterize the pattern of systemic impairment reflected by conventional biomarkers and assess how it relates to clinical outcomes and quality of life among patients hospitalized for heart failure (HF).MethodsPatients hospitalized for HF from 52 hospitals in China were enrolled between 2016 and 2018. They were divided into developing and validating cohorts; the developing cohort was used for calculating the weights of biomarkers and constructing the multi-biomarker panel, while the validating one was used for evaluating the relationship between multi-biomarker points and outcomes. In total, five conventional biomarkers reflecting various pathophysiological processes were included in the panel: N-terminal pro-B type natriuretic peptide, high-sensitivity troponin T, hemoglobin, albumin, and creatinine. The weights of the biomarkers were defined based on their relationship with cardiovascular death, and each patient had a multi-biomarker point ranging from 0 to 12. The primary clinical outcome was cardiovascular death, and the other clinical outcomes included rehospitalization for HF, all-cause death, and all-cause rehospitalization in 1-year. The quality of life was measured using Kansas City Cardiovascular Questionnaire. Multi-variable Cox proportional hazard models were used to assess the risks of clinical outcomes, and generalized linear models were used to evaluate the quality of life.ResultsIn total, 4,693 patients hospitalized for HF were included in this analysis; the median (interquartile range, IQR) age was 67 (57–75) years old and 1,763 (37.6%) were female. The median multi-biomarker point was 5 (IQR, 2–6). There were 18.0% of patients in the low point group (<2), 29.4% in the mid-low point group (2–4), 27.8% in the mid-high point group (5–6), and 24.7% in the high point group (>6). Compared with those in the low point group, the patients in the high point group had a significantly excess risk of cardiovascular death (adjusted hazard ratio: 5.69, 95% CI, 3.33–9.70). Furthermore, patients with higher points were also more prone to worse quality of life.ConclusionSystemic impairment reflected by abnormal conventional biomarker values was common amongst patients hospitalized for HF and had substantially cumulative adverse influence on clinical outcomes and quality of life.

Studies on the dielectric properties of laterally fluorine-substituted multiphenylacetylene-type liquid crystal compounds at microwave region

Liquid crystals have been studied extensively as promising materials for microwave devices due to their dielectric tunability. However, their high dielectric loss remains as a bottleneck which limits the development and application of microwave devices based on LC. We report herein on the dielectric properties of selected fluorine-substituted multiphenylacetylene compounds with a low melting point and polar-NCS group in base matrix at the microwave region (11 ~ 33 GHz). Based on the experimental data, the influence of position and the number of lateral fluorine substituents on the dielectric constant in the high-frequnecy region, as well as on the dielectric loss tangent of LCs, was established.

Distally Based Perforator-Plus Sural Neurocutaneous Flap with High or Low Pivot Point: Anatomical Considerations and a Retrospective Study of a Clinical Series of 378 Flaps.

This study is to describe the distribution of natural true anastomoses associated with the distally based perforator-plus sural neurocutaneous flap (sural flap), summarize our experience in the flap with high pivot point, and compare the outcomes between the flaps with high and low pivot points. Five amputated lower limbs were perfused, and the integuments were radiographed. We retrospectively analyzed 378 flaps, which were divided into two groups: pivot points located ≤8.0 cm (low pivot point group) and >8.0 cm (high pivot point group) proximal to the tip of the lateral malleolus. Partial necrosis rates were compared between two groups. The arterial chain surrounding the sural nerve was linked by true anastomoses from the intermalleolar line to popliteal crease. True anastomoses existed among peroneal perforators and between these perforators and the arterial chain. There were 93 flaps with high pivot point and 285 flaps with low pivot point. Partial necrosis rates were 16 and 9.1% in the high and low pivot point group (p = 0.059), respectively. True anastomosis connections among peroneal perforators and the whole arterial chain around sural nerve enable the sural flap to survive with a greater length. The sural flap with high pivot point is a good option for reconstructing soft-tissue defects in the middle and distal leg, ankle, and foot, particularly when the lowest peroneal perforator presents damage, greater distance to the defects, discontinuity with the donor site, or anatomical variation.

The effect of the synthesis conditions on the structure and phase transitions in Ln2(MoO4)3

The effect of the lanthanide cation type and calcination temperature on the structure and phase transitions in Ln2(MoO4)3 molybdates was studied using synchrotron X-ray diffraction, infrared and Raman spectroscopy, photoluminescence, simultaneous thermal analysis and inductively coupled plasma atomic emission spectroscopy. It was found that the crystallization of the precursors at 500∘ C/3 h results in the formation of nanocrystalline powders with the monoclinic structure (sp. gr. I112/b (15)) for Ln2(MoO4)3 (Ln = La–Ho), and a mixture of orthorhombic (sp. gr. Pnca(60)) and tetragonal (sp. gr. I41/a(88)) phases for Yb2(MoO4)3. A further increase in temperature to 1000∘ C leads to a significant rearrangement of the crystal structure, which is largely determined by the lanthanide type. The diagram of phase relations in the Ln2(MoO4)3 molybdates as a function of the Ln3+ cation radius and the calcination temperature has been refined. According to the results of Raman and IR spectroscopy, MoO4 tetrahedra are the main structural units in Ln molybdates. The increased hygroscopicity of heavy lanthanide molybdates (Ln = Ho, Yb) is associated with the presence of empty cavities in the orthorhombic structure. The photoluminescence spectra have shown that EuOn polyhedra in Eu2(MoO4)3 are distorted, and Eu3+ ions occupy several nonequivalent crystallographically different sites with a low symmetry point group.

Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7

Recently, a local-Ising-type magnetic order was inferred from neutron diffraction of the antiferromagnetic ${\mathrm{Er}}_{2}{\mathrm{Ge}}_{2}{\mathrm{O}}_{7}$ (pg-ErGO) with an applied magnetic field. Here, we use neutron spectroscopy to investigate the energetics of pg-ErGO and the isostructural ${\mathrm{Yb}}_{2}{\mathrm{Ge}}_{2}{\mathrm{O}}_{7}$ (pg-YbGO) to evaluate the adequacy of the local-Ising description. To begin, we generate a model of the magnetic structure of pg-YbGO using neutron diffraction and find a net ferromagnetic moment. While pg-ErGO and pg-YbGO have highly symmetric crystal structures ($P{4}_{1}{2}_{1}2$ tetragonal space group 92) with only one trivalent rare-earth magnetic site, the point symmetry of the rare-earth site is low with only a single symmetry element (point group ${\mathrm{C}}_{1}$). For both compounds, the energy scale of the first excited state is large compared to the magnetic ordering temperature, suggesting Ising character. The ground-state Kramer's doublet of both compounds is dominated by the maximal ${m}_{\mathrm{J}}$ component. However, the low point group symmetry of the rare-earth site leads to finite mixing of all other ${m}_{\mathrm{J}}$'s, which suggests potential deviations from Ising behavior. Moreover, quasielastic scattering is observed deep in the ordered state of pg-ErGO and pg-YbGO that may be due to non-Ising behavior. The dominant magnetic interaction in both compounds is found to be magnetostatic by considering the magnetic excitations in the ordered state. From consideration of these data, the pg-YbGO is more Ising-like than pg-ErGO. Also, quantum multicritical points are anticipated with applied magnetic field in both compounds.

Synthesis and Magneto-Structural Characterization of Yb3(OH)7SO4·H2O: a Frustrated Quantum Magnet with Tunable Stacking Disorder.

The quenched structural disorder in frustrated magnets can lead to apparent quantum spin liquid (QSL) behavior or to a valence bond glass state: the transition between these thermodynamic states has not been demonstrated experimentally. Herein, we report the synthesis of a novel layered rare earth hydroxide Yb3(OH)7SO4·H2O as single crystals. The interplay between the strong distortion of the triangular lattice and low point group symmetry of the three distinct Yb3+ sites leads to quenched disorder. The variable stacking disorder in Yb3(OH)7SO4·H2O is elucidated by comparison to the lutetium analogue, Lu3(OH)7SO4·H2O. The degree of disorder in Yb3(OH)7SO4·H2O is controlled by the chemical form of the starting material and solution pH. In a low magnetic field, Yb3(OH)7SO4·H2O displays QSL behavior, while, under a high field, a valence bond glass state is observed. The degree of stacking fault disorder in Yb3(OH)7SO4·H2O modulates the observed magnetic properties and the transition between QSL and valence bond glass states.

Test design and individual analysis in wheelchair rugby

ObjectivesUse a task vehicle of sprint testing in wheelchair rugby (WCR) to explore the impact of small changes to test design using both group and individual analysis. DesignExploratory, repeated measures, on-court study Method25 national or international level wheelchair rugby players completed 5×5m sprints under two conditions: (i) an acceleration from standstill in their own time, and (ii) an ‘active’ start, simulating a key aspect of performance. Video analysis and accelerometer data were used to measure key kinematic and performance variables with a focus on the first three strokes. Each player was grouped into a high-, mid-, or low-point group based on their sport-specific classification score. Group (paired sample t-tests) and individual (meaningful differences, performance coefficients, and Cohen’s d effect sizes) analysis assessed differences between the two conditions. ResultsThe low-point classification group performed significantly slower in the active start (p<0.05). There were no differences in sprint time for the high- and mid-point groups. Mid-point players achieved greater peak accelerations for strokes two and three in the active start (p<0.05). Individual sprint performances varied substantially, ranging from 8% decrease to 14% increase in sprint time for the active start. Meaningful differences in peak accelerations were demonstrated for 23 out of the 25 players. ConclusionsSmall amendments to test design can lead to significant differences in individual athlete performance. Traditional group analyses masked important individual responses to testing conditions. There is need to further consider representative test design, and individual analysis for monitoring physical and skill performance.

NKG2C+NKG2A- Natural Killer Cells are Associated with a Lower Viral Set Point and may Predict Disease Progression in Individuals with Primary HIV Infection.

Natural killer (NK) cells are the first line of defense against pathogens of the immune system and also play an important role in resistance against HIV. The activating receptor NKG2C and the inhibitory receptor NKG2A co-modulate the function of NK cells by recognizing the same ligand, HLA-E. However, the role of NKG2A and NKG2C on viral set point and the prediction of HIV disease progression have been rarely reported. In this study, we determined the expression of NKG2C or NKG2A on the surface of NK cells from 22 individuals with primary HIV infection (PHI) stage and 23 HIV-negative normal control (NC) subjects. The CD4+ T cell count and plasma level of HIV RNA in the infected individuals were longitudinally followed-up for about 720 days. The proportion of NKG2C+NKG2A− NK cells was higher in subjects from the low set point group and was negatively correlated with the viral load. In addition, strong anti-HIV activities were observed in NKG2C+ NK cells from the HIV-positive donors. Furthermore, a proportion of NKG2C+NKG2A− NK cells >35.45%, and a ratio of NKG2C/NKG2A >1.7 were predictive for higher CD4+ T cell counts 720 days after infection. Collectively, the experimental results allow us to draw the conclusion that NKG2C+ NK cells might exert an antiviral effect and that the proportion of NKG2C+NKG2A− NK cells, and the ratio of NKG2C/NKG2A, are potential biomarkers for predicting HIV disease progression.

Seated limits-of-stability of athletes with disabilities with regard to competitive levels and sport classification.

In this study, we asked whether wheelchair rugby (WR) classification and competitive level influence trunk function of athletes with disabilities, in terms of seated limits-of-stability (LoS). Twenty-eight athletes were recruited from international- and national-level WR teams, with each group exhibiting marked differences in years of sports practice and training volume. Athletes were also distributed into three groups according their classification: low-point (0.5-1.5-point); mid-point (2.0-2.5-point); and high-point (3.0-3.5-point). Athletes were asked to sit on a force platform and to lean the body as far as possible in eight predefined directions. Center of pressure (COP) coordinates were calculated from the ground reaction forces acquired with the force platform. LoS were computed as the area of ellipse adjusted to maximal COP excursion achieved for the eight directions. ANOVAs reveal that LoS were not different when international- and national-level players were compared (P=.744). Nevertheless, LoS were larger in players from the high-point group than from the low-point group (P=.028), with the mid-point group being not different from both (P>.194). In summary, (i) competitive level does not impact LoS measures and (ii) LoS are remarkably distinct when comparing both extremes of the WR classification range. Our results suggest that, as a training-resistant measure, LoS could be a valid assessment of trunk impairment, potentially contributing to the development of an evidence-based WR classification.

직접교수법에 의한 기초공학(물리학)에서 학습장애자 교육

이 연구는 직접교수법을 적용해 기초공학의 일부인 물리학 수업에서 발생하는 교육장해학생에 대한 교육을 다루었다. 이 직접교육이란 교육자가 수업방향을 분명히 잡고 강력하게 이끄는 것이 중요한 교육요소인 방법론이다. 임의의 학생 100명에 대해 문제해결에 대한 이해력, 추리력, 기억력, 문제해결속도를 측정하여 20명(20%) 학생이 기초공학장애자로 나타났다. 한편, 직접교육을 통해 표본그룹(41명)의 중간고사와 기말고사에서 각각 53.7%와 61.0%의 성적을 거두어서 13.6% 증가를 보여주었으나 성적 50% 이하인 하위 그룹은 각각 29.8%와 28.2%를 거두어 오히려 감소하였다. 그러나 특별히 성적 최하위 20%인 8명의 학생을 학습장애자로 선정하여 별도로 여가의 직접교육을 수행하였고 이들은 중간고사 및 기말고사 평균점수는 각각 18.9%와 25.5% 로써 6.6% 증가를 보여주어 학습장애자들에 대한 직접교육이 실효가 있음을 보여주었다. The Direct Instruction (DI) was applied to the learning-disabled in the basic engineering education (especially, physics education). The DI is specified as an educational method in which the instructor strongly controls during the whole process of the entire course. The tests of understanding, reasoning, memory, and problem-solving speed showed that 20 students (20%) out of random 100 students are learning-disabled. The average points of mid-term and final exams were 53.7% and 61.0% respectively for a certain 41-students class. However, in this class, for the lower point students who obtained less than 50% points, the average points of mid-term and final exams were 29.8% and 28.2% respectively, which showed decreased. From this lower point group, the 8 students (20% students of 41 students) were selected as the learning-disabled. With additional DI studies provided, the average points of mid-term and final exams for the learning-disabled were 18.9% and 25.5% respectively, which showed 6.6% increase that means the DI for the learning-disabled was effective.

Colloidal spirals in nematic liquid crystals.

One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry. Colloidal particles also exhibit both stable and metastable multiple orientational states in the nematic host, with a large number of director configurations featuring both singular and solitonic nonsingular topological defects accompanying them, which can result in unusual forms of colloidal self-assembly. Our findings directly demonstrate how the symmetry of particle-generated director configurations can be further lowered, or not, as compared to the low point group symmetry of solid micro-inclusions, depending on the nature of induced defects while satisfying topological constraints. We show that achiral colloidal particles can cause chiral symmetry breaking of elastic distortions, which is driven by complex three-dimensional winding of induced topological line defects and solitons.

도마종목 Kasamatsu계의 Akopian 기술동작 분석

The study were to assess technical factors between the high score group and the low score group, from the subjects of 16 male national gymnasts, and to analyze the kinematical characteristic and main technical cause on technique of Akopian`s 3D motion analysis of the male vaulting game in 2001 classification championship. The result of this study is this. There were not so much difference between the two groups in term; of the time of board contact, pre-flight, and total performance, but it takes shorter time when the players who are in the high point group take down the board, and they take long time for post-flight(p, but there weren`t significantly statistic differences between two groups. The hight score group were 0.68m/s faster than the low point group at the horizontal velocity at board take off event( on the average. the comparative groups show almost same results. When horse taking off, the HPVy of the high point group were 37.6 degree which were a little higher than the low point group. The angular velocities of the players who takes on the horse with a right hand and then takes off with a left hand in the high point group were 14.97rad/sec, 10.82rad/sec in the low point group. However, the angular velocity of the players who takes on the horse with a left hand and then takes off on a right hand with the high point group were 14.97rad/sec, 15.56rad/sec in the low point group.

The crystal structures and electronic properties of three new [Cu(bipy) 2(ONO)][Y] complexes. The structural pathway of the [Cu(bipy) 2(ONO)][Y] series of complexes. Further insights into the Pseudo Jahn–Teller model

The crystal structures of three new [Cu(bipy) 2(ONO)][Y] complexes, [Y] −=[PF 6] −, 1, [ClO 4] −, 2, and [I] −, 3, have been determined at room temperature by single crystal X-ray analysis. All three complexes involve a CuN 4O 2 chromophore, with an asymmetric cis-distorted octahedral (CDO) stereochemistry. The stereochemistries of 1, 2 and 3, are compared with three other cation distortion isomers, [Y] −=[NO 3] −, 4, [BF 4] −, 5, and [HSO 4] −, 6, by scatter plot analysis to characterise a possible structural pathway involving the [Cu(bipy) 2(ONO)] + cation only, accounting for the occurrence of discrete α 3 angles and right-pointing arrowhead structures, features which are not readily accounted for by the original tris-chelate Jahn–Teller/ Pseudo Jahn–Teller (JT/PJT) model. Further insights into the stereochemistry of the CuN 4O 2 chromophore as an independent PJT system involving vibronic coupling between the degenerate 2A type ground state in low point group symmetry ( C 2 or C 1 symmetry) and a corresponding excited state are presented. This paper raises some question marks about the original PJT model of CDO chromophores which do not take into account the experimental observation of the ranges of the α 3 discrete angles or the arrowhead fine structure of the data, within the range of the cluster of α 3 angles.

Conditions inducing fertility alteration and ecological adaptation of photoperiod-sensitive genic male-sterile rice

The pollen fertility of photo-sensitive genic male-sterile (PGMS) lines is regulated interactively by photoperiod and temperature. There is a temperature range within which the pollen fertility alteration of PGMS is regulated by photoperiod, being sterile at long days and fertile at short days. The critical values of day length and temperature vary as the PGMS gene(s) is (are) transferred into different genic backgrounds. According to the temperature reactions in response to fertility alterations, the current sterile lines fall into four photothermal types. The climatic adaptation of these is different. Lines of the high-low (a high critical fertile temperature with a low critical sterile temperature point) group have both stable sterile and fertile periods in the low-altitude subtropical rice-growing areas, which are the major rice-production areas of the world. We could exploit them in hybrid rice production there by a two-line method, because there is no need for both male-sterile and maintainer lines. At high altitudes of the subtropical and tropical rice-growing areas, lines of this group are unstable in their sterility. The low-low group is stable in sterility in long-day conditions at all temperatures, and at high temperatures despite day length. They could be used for hybrid seed production from the tropical through to temperate rice-growing conditions. However, their pollen fertility, and hence, seed multiplication, is easily lost in short days if high temperatures occur. The high-high group of sterile lines can be conveniently multiplied in short days, but their sterility is not stable in long days if temperature decreases in the critical fertility alteration period. The low-high group is stable at higher temperature irrespective of photoperiod, and this could be used in the tropics, but their sterilities are not stable in long days if lower temperatures are encountered. Their multiplication in short-day conditions may also be affected by high temperature.

Cloning of two xylanase genes from the newly isolated actinomycete Actinomadura sp. strain FC7 and characterization of the gene products

A screening program was established to find actinomycetes that produce xylanases able to hydrolyze xylan chains in a hemicellulose liquor (a by-product of steam treatment of the lignocellulosic biomass) at moderately acidic pH (4.0) and high temperature (70 °C). The first step involved a selection for xylanolytic actinomycetes having optimal growth at 50–60 °C. In the second step, the crude enzymes produced by the selected actinomycetes were compared for their xylan hydrolysis rates at pH 5 and 60 °C versus pH 4 and 70 °C. The crude enzymes produced by strain FC7 retained 65% of their activity under the more stringent of the two conditions. FC7 was identified as a member of the genus Actinomadura by chemotaxonomic procedures. A gene bank of FC7 was constructed using the shuttle vector pFD666. The plasmids were introduced into a periplasmic-leaky Escherichia coli host to rapidly detect xylanolytic recombinants. Two classes of recombinants were isolated. The plasmids pJFl and pJF6 were introduced into a xylanase- and cellulase-negative mutant of Streptomyces lividans, allowing overproduction and subsequent purification of two different xylanases, Xyl I and Xyl II. Both enzymes were classified in the low isoelectric point group of xylanases. In the presence of 100 μg/mL of bovine serum albumin, the half-life of Xyl I at pH 4 and 70 °C was 22 h.Key words: xylanase, thermophilic actinomycetes, Actinomadura, thermostability.