Direction Of Long Axis Research Articles

Spontaneous space closure after extraction of young first permanent molar. Retrospective cohort study.

Early compromised first-permanent-molar (FPM) extraction can adversely affect occlusion. However, the current literature does not provide sufficient support for definitive early extraction outcome. This cohort study aimed to evaluate the pattern of post-FPM extraction spontaneous space closure and its pre-extraction indicators. Patients of 7-13 years, with compromised FPM at three-tertiary-centers between 2015 and 2019 were retrospectively screened. Pre-extraction indicators were evaluated (extraction location, direction of the second permanent molar (SPM) long-axis, and SPM Demirjian development stage). Spontaneous space closure pattern was evaluated clinically and radiographically using the American Board of Orthodontics (ABO) grading system. In total, 112 FPMs (73-patients) were identified and five (4.5%) of the extraction sites showed favorable combined-ABO-scores. Distal direction of the SPM long-axis in the maxillary arch significantly decreased the relative risk (RR) of having a SPM rotation/alignment ABO score-1 (P = 0.002; RR = 0.64). For the mandibular arch, Demirjian stage D and E significantly decreased the RR of having ABO score-1 for spacing between the SPMs and second premolars (P = 0.029; RR:0.57, P = 0.004; RR:0.53, respectively) and vertical dimension (P = 0.02; RR = 0.53). The direction of the SPM long-axis and its developmental stage are key indicators of the favorable outcome pattern of spontaneous space closure after FPM early extraction.

DEM simulation of microscopic structure and macroscopic mechanical behavior of clay in oedometer and triaxial compression tests

An updated DEM simulation scheme for clay is implemented by incorporating convex polygon shaped platelets and robust algorithm for physico-chemical–mechanical interaction between clay platelets. Clays with two typical microscopic structures, i.e., card-house structure and book-house structure, are simulated in oedometer test and triaxial compression test. Virtual Mercury Intrusion Porosimetry (MIP) and pore segmentation algorithms are utilized to extract pore statistics from the numerical samples. The simulation results and experimental results from the literature are thoroughly compared at both macroscopic and microscopic scales. It is found that the implemented DEM simulation scheme can satisfactorily reproduce the experimentally observed macroscopic behavior of clay. Especially, in triaxial compression tests, the critical state behavior, stress-dilatancy relationship and over-consolidation effects are generally consistent with existing experimental results. General consistency in pore size, orientation and shape distributions in DEM simulations and experiments can be observed. Clay platelets tend to rotate to align their normal directions along the major principal stress direction, while pores tend to align their long-axis directions in the confinement direction, leading to dynamically evolving fabric anisotropy. In the book-house structure clay, clay domains experience multiple deformation modes, including uniaxial compaction, shear distortion, spatial spin, and their combinations.

Selecting Flap Transfer Methods to Repair Helix Soft Tissue Defect Based on the Direction of Long Axis.

The posterior auricular flap has long been favored for repairing skin defects on the ear's surface. However, achieving optimal esthetic outcomes in ear reconstruction requires a flexible approach to flap transfer methods. While bipedicle advancement flaps are commonly used for body wound coverage, they are rarely used in auricular defect repair. To propose a modified flap transfer approach based on the orientation of the auricular defect's long axis and assess the postoperative esthetic outcomes. The authors reported 12 patients treated using 2 distinct flap transfer techniques. Mild to moderate helix soft tissue defects remained after excision of the masses. A direct island flap was created for patients with longitudinal defects to cover the defect. For patients with transverse defects, a combination of bipedicle and island flaps was used for repair. Scar quality and esthetic outcomes were assessed at least 6 months postsurgery using the Scar Cosmesis Assessment and Rating scale. All patients experienced no serious complications and achieved excellent cosmetic results. Patients undergoing combined flap transfer exhibited relatively more favorable esthetic outcomes. The authors propose a novel concept for repairing helix soft tissue defects by designing local flaps based on the direction of the defect's long axis. For repairing helix soft tissue defects with a long axis parallel to the auricular edge, the combined utilization of bipedicle advancement flap and island rotation flap transfer should be consideration more.

The microstructural evolution and mechanical response of laser direct energy deposition Inconel 718 alloy based on simulation and experimental methods

During laser directed energy deposition (LDED), the complex microstructure created by multiple rapid heating and cooling cycles results in the uneven performance of the parts. This work investigates the microstructure evolution and mechanical properties of LDED Inconel 718 samples with different deposit shapes of single-track and thin-wall. The crystal plasticity constitutive and statistical microstructure modeling combined with experiments were performed to explore the influence of microstructure on tensile property. Compared to the thin-wall samples, the single-track sample has smaller sub-grains because of the higher cooling rate, resulting in higher hardness. Furthermore, the anisotropy of the mechanical properties is not changed by the scanning strategy, although the grain size and the yield strength with the Hall-Petch relation are affected by the scanning strategy. The slip system with maximum and secondary Schmid factors is more easily activated during deformation. The rotational behavior of the grains suggests that the anisotropy of mechanical properties is closely linked to the dominant texture of the 〈001〉 orientation crystals, including the dominant direction of the grain long axis and the ratio of the long and short axis. The results can provide guidance for understanding the deformation mechanism of LDED parts and optimizing the strength design.

Analysis of left ventricle regional myocardial motion for cardiac radioablation: Left ventricular motion analysis.

Left ventricle (LV) regional myocardial displacement due to cardiac motion was assessed using cardiovascular magnetic resonance (CMR) cine images to establish region-specific margins for cardiac radioablation treatments. CMR breath-hold cine images and LV myocardial tissue contour points were analyzed for 200 subjects, including controls (n=50) and heart failure (HF) patients with preserved ejection fraction (HFpEF, n=50), mid-range ejection fraction (HFmrEF, n=50), and reduced ejection fraction (HFrEF, n=50). Contour points were divided into segments according to the 17-segment model. For each patient, contour point displacements were determined for the long-axis (all 17 segments) and short-axis (segments 1-12) directions. Mean overall, tangential (longitudinal or circumferential), and normal (radial) displacements were calculated for the 17 segments and for each segment level. The greatest overall motion was observed in the control group-long axis: 4.5±1.2mm (segment 13 [apical anterior] epicardium) to 13.8±3.0mm (segment 6 [basal anterolateral] endocardium), short axis: 4.3±0.8mm (segment 9 [mid inferoseptal] epicardium) to 11.5±2.3mm (segment 1 [basal anterior] endocardium). HF patients exhibited lesser motion, with the smallest overall displacements observed in the HFrEF group-long axis: 4.3±1.7mm (segment 13 [apical anterior] epicardium) to 10.6±3.4mm (segment 6 [basal anterolateral] endocardium), short axis: 3.9±1.3mm (segment 8 [mid anteroseptal] epicardium) to 7.4±2.8mm (segment 1 [basal anterior] endocardium). This analysis provides an estimate of epicardial and endocardial displacement for the 17 segments of the LV for patients with normal and impaired LV function. This reference data can be used to establish treatment planning margin guidelines for cardiac radioablation. Smaller margins may be used for patients with higher degree of impaired heart function, depending on the LV segment.

Deformation mechanism and mechanical properties of a CoCrFeNi high-entropy alloy via room-temperature rolling, cryorolling, and asymmetric cryorolling

The deformation mechanism and mechanical properties of CoCrFeNi high-entropy alloys (HEA) processed by room-temperature rolling (RTR), cryorolling (CR) and asymmetric cryorolling (ACR) were studied. As the rolling reduction increased from 20 % to 80 %, a transition in the dislocation and twinning deformation mechanisms occurred. The cryogenic environment in rolling process can promote the activation of the twins in the HEA at a lower strain, improving the deformation efficiency. The introduction of differential speed ratio led to the finer micro-shear bands with a more uniform distribution, so that the grains were refined to a greater extent. In the ACR HEA after large deformation, the stacking faults accumulated inside the deformation twins further refined the twins along the direction of long axis. This increased the strength of ACR HEA together with Lomer-Cottrell locks and FCC/HCP boundaries, reaching the maximum value compared with CR and RTR. The ultimate tensile strength exceeded 1450 MPa, and the yield strength of ACR HEA increased by nearly 1200 MPa compared to the initial material, while it still maintained the same elongation as RTR and CR. ACR showed the best strength-ductility combination during the whole rolling deformation process. The microstructure evolution and the strengthening contribution mechanism of different rolling were discussed and calculated, and the specific mechanism of how the introduced differential speed ratio further improves the strength-ductility synergistic strengthening in CR was clarified.

Tidal dissipation within an elongated asteroid with satellite, and application to asteroid (216) Kleopatra

(216) Kleopatra is a highly elongated dumbbell shaped asteroid, which is spinning rapidly (spin period 5.38 h), and has two satellites. The tidal migration rate of its outer satellite (related to asteroid tidal despinning) has been measured by Broz et al. (2021), and is used here to deduce the elastic properties of the asteroid, in particular its rigidity μ. For this purpose the satellite is modeled as an homogeneous elongated axisymmetric body, whose shape is described either as a cylinder or more realistically as a dumbbell. Such model asteroid is regarded as a beam (or rod) that undergoes tidal disturbances from the satellite. Due to the deformability of the asteroid, the tidal stresses produced within the body rise a compression tide in the direction of the asteroid's long axis, and a bending tide in the perpendicular direction. We compute the tidal amplitude of the total elastic energy stored within the asteroid, as a function of Young's modulus E. Provided that the tidal quality factor Q is known, this permits to deduce the power tidally dissipated within the asteroid. This is compared to the tidal dissipation deduced from Broz et al. (2022) observations of the tidal migration of Kleopatra's outer satellite. This permits to deduce the asteroid's Young's modulus E (or equivalently the rigidity μ through μ ≈ E/(2.6 ± 0.1)). Using our dumbbell model for Kleopatra, we obtain a rigidity μ ≈ 1.94 × 107 Pa if one assumes Q ≈ 40, or μ ≈ 1.40 × 107 Pa if one assumes Q = 100. Such tidal dissipation is found to be >2 orders of magnitude higher than the tidal dissipation which would occur in a hypothetical spherical asteroid of same density and rigidity as Kleopatra, with radius equal to the volume equivalent radius (RV ≈ 59.1 km). Among model asteroids with same long axis length as Kleopatra (2 L ≈ 267 km), dissipation is also found to be strongly dependent upon the shape of the asteroid (dumbbell, cylinder, or ellipsoid). Here the asteroid is regarded as an elastic solid, whereas it is presumably a weak rubble pile medium. The formalism developed here is however relevant provided that the asteroid may be regarded as a Maxwell material, because tidal frequencies are expected to be much higher than the inverse Maxwell time.

Magnetic Field Sensor Based on a Fiber Taper Integrated in a Magnetic Polymer Micro-Ellipsoid

In this article, a highly sensitive magnetic field sensor based on a fiber taper integrated in a magnetic polymer micro-ellipsoid was proposed. The magnetic polymer micro-ellipsoid was formed by coating and curing the magnetic polymer material on the fiber taper. The length of the fiber taper is 600 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> . The lengths of the magnetic polymer micro-ellipsoid along short- and long-axis directions are 830 and 1250 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> , respectively. The incident light was divided into two beams at the fiber taper. The two beams transmitting along the fiber taper and magnetic polymer micro-ellipsoid separately form the Mach–Zehnder (M-Z) interference. The refractive index and the interference length change along with the magnetic field variation, which results in the interference spectrum shift. The magnetic field sensitivity is up to −61.8 pm/mT. The sensor will have important applications in medical care, aerospace, and other fields due to its high sensitivity, simple preparation, and low cost.

Impact of Shelf Valleys on the Spread of Surface-Trapped River Plumes

AbstractThis study focuses on mechanisms of shelf valley bathymetry affecting the spread of riverine freshwater in the nearshore region. In the context of Changjiang River, a numerical model is used with different no-tide idealized configurations to simulate development of unforced river plumes over a sloping bottom, with and without a shelf valley off the estuary mouth. All simulated freshwater plumes are surface-trapped with continuously growing bulges near the estuary mouth and narrow coastal currents downstream. The simulations indicate that a shelf valley tends to compress the bulge along the direction of the valley long axis and modify the incident angle of the bulge flow impinging toward the coast, which then affects the strength of the coastal current. The bulge compression results from geostrophic adjustment and isobath-following tendency of the depth-averaged flow in the bulge region. Generally, the resulting change in the direction of the bulge impinging flow enhances down-shelf momentum advection and freshwater delivery into the coastal current. Sensitivity simulations with altered river discharges Q, Coriolis parameter, shelf bottom slope, valley geometry, and ambient stratification show that enhancement of down-shelf freshwater transport in the coastal current, ΔQc, increases with increasing valley depth within the bulge region and decreasing slope Burger number of the ambient shelf. Assuming potential vorticity conservation, a scaling formula of ΔQc/Q is developed, and it agrees well with results of the sensitivity simulations. Mechanisms of valley influences on unforced river plumes revealed here will help future studies of topographic influence on river plumes under more realistic conditions.

Till kinematics in the Stargard drumlin field, NW Poland constrained by microstructural proxies

ABSTRACTDeciphering the relationships between streamlined subglacial landforms and deposits therein helps to constrain the dynamics of past ice sheets. Here we present microstructural analyses of till from the largest drumlin field in the North European Lowland generated by a major palaeo‐ice stream of the Scandinavian Ice Sheet. Data derived from thin sections and X‐ray microtomography (μCT) reveal multiple microstructures including microshears, circular structures, grain stacks and crushed grains. Long axes of micro‐clasts measured in thin sections are directionally clustered and have low, down‐ice‐oriented dip angles. Some samples reveal subordinate clustering oriented at high angles to the main direction. The μCT data show low clustering strengths of clasts and no systematic fabric pattern in the entire set of samples. There is no correspondence between the clast orientations and the directions of drumlin long axes, suggesting that the till is antecedent in relation to the drumlin‐shaping process. The observations indicate spatially and temporally variable, shallow‐seated brittle and ductile deformation controlled by porewater pressure fluctuations and generated time‐transgressively parallel to till accretion. Consistently with previous studies, the data suggest that the Stargard drumlins are erosional remnants of a pre‐existing terrain shaped by material removal from the inter‐drumlin areas.

Generalized Kasha’s Model: T-Dependent Spectroscopy Reveals Short-Range Structures of 2D Excitonic Systems

Summary Excitonic organic materials owe their tunable optoelectronic properties to intricate microscopic configurations, challenging for conventional characterization methods to resolve. We generalize Kasha’s model by incorporating the temperature (T)-dependent absorption peak shift, in addition to the monomer-aggregate absorption peak shift that defines J- and H-aggregates, to characterize the microscopic structures. We show that the short-range interactions dominate in determining the direction of the T-dependent peak shift, which accounts for previously observed T-dependent blueshifting J-aggregates (BJ-aggregates) that were not explained and predicts the existence of redshifting H-aggregates (RH-aggregates). This defines four types of excitonic aggregates: RJ-, BH-, BJ-, and RH-aggregates, where the latter two unconventional aggregates are possible because of the two dimensionality of excitonic systems and cannot be understood with the original Kasha’s theory. Our conceptual framework is useful for elucidating structure-function relationships in molecular excitonic systems and is fully compatible with existing tools. Possible extensions to other spectroscopic observables and related systems are discussed.

Investigation on the growth of snowflake-shaped Poly(l-Lactic acid) crystal by in-situ high-pressure microscope

Crystallization of polymer film is a widely concerned condensed matter phenomenon directly determining the film properties and performances. However, challenging on understanding of the crystal growth process of polymer thin film still remains. Here, we developed an in-situ high-pressure observing system to record the crystal growth process of Poly(l-Lactic Acid) (PLLA) film in pressurized CO2 environment with different film thicknesses, molecular weights, temperatures and CO2 pressures. The preliminary stage of morphological evolution of snowflake-shaped crystal was recorded for the first time. Based on the morphological feature and microscopic structure, we found that the snowflake-shaped crystal with six main branches is constructed by multilayer rhombic terrace crystal originated from screw dislocation, and the six main branches are not formed at the same time. Two of them are preferentially formed on the long-axis directions of rhombic crystal, while the other four main branches are subsequently formed. The subsequently formed branches root from twin crystal induced from self-generated concentration field. The growth process of snowflake-shaped PLLA crystal is quite different from that of snowflake-shaped H2O crystal, but still meets the self-similarity principle and iterative generation principle of the fractal theory.

Insufficient Leiomyoma Infarction in Uterine Artery Embolization: Relationship with Tumor Location

PurposeTo evaluate which leiomyoma location in the uterus predicts insufficient tumor infarction after uterine artery embolization (UAE). Materials and MethodsIn this single-institution retrospective study, 45 patients (mean age, 43.4 y ± 4.1) underwent UAE for leiomyomas using trisacryl gelatin microspheres alone with “pruned-tree” endpoint performed by qualified interventional radiologists between October 2015 and July 2017. Technical outcomes and complications were assessed. All patients underwent unenhanced and enhanced MR imaging before and after UAE. A total of 476 tumors of ≥ 1 cm observed in all patients were evaluated. Multivariate generalized linear mixed model analysis was performed to investigate relationships between insufficient tumor infarction (< 90%) on contrast-enhanced MR imaging after UAE and baseline factors, including tumor location in the long-axis, front-back, and inner-outer directions and tumor size. ResultsAll patients successfully underwent UAE with no major complications. Multivariate analysis revealed that there was a higher likelihood of insufficient infarction of tumors at the cervix (odds ratio [OR] 80.45; 95% confidence interval [CI] 9.97, 649.09; P < .001) and lower body (OR 4.31; 95% CI 2.52, 7.38; P < .001) than at the upper body and of tumors at the front than at the back wall (OR 2.20; 95% CI 1.32, 3.67; P = .002). Tumor size (OR 0.71; 95% CI 0.61, 0.82; P < .001) was a significant factor, whereas tumor location in the inner-outer direction was not. ConclusionsInsufficient leiomyoma infarction after UAE was more likely to involve tumors at the cervix, lower body, or front wall of the uterus or smaller tumors.

Biomechanical Analysis Using FEA and Experiments of Metal Plate and Bone Strut Repair of a Femur Midshaft Segmental Defect.

This investigation assessed the biomechanical performance of the metal plate and bone strut technique for fixing recalcitrant nonunions of femur midshaft segmental defects, which has not been systematically done before. A finite element (FE) model was developed and then validated by experiments with the femur in 15 deg of adduction at a subclinical hip force of 1 kN. Then, FE analysis was done with the femur in 15 deg of adduction at a hip force of 3 kN representing about 4 x body weight for a 75 kg person to examine clinically relevant cases, such as an intact femur plus 8 different combinations of a lateral metal plate of fixed length, a medial bone strut of varying length, and varying numbers and locations of screws to secure the plate and strut around a midshaft defect. Using the traditional “high stiffness” femur-implant construct criterion, the repair technique using both a lateral plate and a medial strut fixed with the maximum possible number of screws would be the most desirable since it had the highest stiffness (1948 N/mm); moreover, this produced a peak femur cortical Von Mises stress (92 MPa) which was below the ultimate tensile strength of cortical bone. Conversely, using the more modern “low stiffness” femur-implant construct criterion, the repair technique using only a lateral plate but no medial strut provided the lowest stiffness (606 N/mm), which could potentially permit more in-line interfragmentary motion (i.e., perpendicular to the fracture gap, but in the direction of the femur shaft long axis) to enhance callus formation for secondary-type fracture healing; however, this also generated a peak femur cortical Von Mises stress (171 MPa) which was above the ultimate tensile strength of cortical bone.

Reliquefaction behavior of sand and its mesoscopic mechanism

Instances of historical earthquakes demonstrated that sandy grounds can liquefy more than once (reliquefaction) when earthquakes occur in succession (e.g., the main shock and aftershocks). Previous laboratory experiments proved that the resistance of sand to reliquefaction might be lower after its first liquefaction despite an increase in density after the first liquefaction. To clarify the reliquefaction behavior of sand and its mesoscopic mechanism, a series of small-scale shaking table tests were performed for different shaking durations on a sand specimen to simulate multiple liquefactions. Mesoscopic images of the sand particles were taken with a stereomicroscope and an industrial camera both before and after each liquefaction. Then, a digital image processing technique was used to obtain the mesoscopic parameters of the sand particles, namely, the apparent void ratio, long-axis direction, and average coordination number. The test results demonstrated that the sand specimen could reliquefy up to three times according to various shaking durations, suggesting that the density of the sand specimen plays a significant role in the reliquefaction behavior of sand. The analysis of the mesoscopic parameters indicated that the long-axis directions of sand particles are prone to be horizontal in the initial state (before the first liquefaction), whereas after liquefaction and redeposition, the long-axis directions tend to be vertical, suggesting that the decrease in reliquefaction resistance results from the change in the mesoscopic structure of the sand.

Oriented graptolites in the Uppermost Ordovician Wufeng black shale in southern China

Graptolites are elongated fossils that can be used to decipher the current direction to evaluate paleocurrent conditions. Abundant graptolite fossils are well-preserved and clearly exhibit strong alignment in the black shales of the Upper Ordovician Wufeng Formation on the southern edge of the Upper Yangtze Sea, South China. The orientations of these graptolites indicate that the remains of graptolites were deposited on the seafloor under the influence of currents, instead of under calm water conditions. Based on the measurements of the long-axis directions of graptolites, the distributions of graptolites preserved on the bedding planes display discernable orientations and exhibit systematic changes throughout the stratigraphic section. In the western region of the study area, the paleocurrent directions in the stratigraphic sections gradually change from NE–SW in the Dicellograptus complexus biozone to N–S in the Paraorthograptus pacificus and Normalograptus extraordinarius–N. ojsuensis biozones. However, in the eastern region of the study area, the paleocurrent directions are more variable, ranging from multi-directional (NNE–SSW and NNW–SSE) in the P. pacificus biozone to NW–SE in the N. extraordinarius–N. ojsuensis biozone. The changes in the orientations of graptolites in the D. complexus and the P. pacificus biozones are consistent with the southern configuration of the Upper Yangtze Sea and indicate that a coastal current existed. In addition, some of the contemporaneous deformation structures were caused by tectonic forces observed in the lower Graptolite Shale Member of the Wufeng Formation in the eastern region of the study area. Some of the changes in the orientations of graptolites in the N. extraordinarius–N. ojsuensis biozone can be interpreted to have resulted from a change in tectonic activity (the Caledonian orogeny) before the N. extraordinarius–N. ojsuensis biozone. Furthermore, Lingula brachiopods, which live on the seafloor in shallow water, have been reported in the black shale of the Wufeng Formation, which indicates that the paleoenvironment was at least partially oxic; this supported the growth, development and reproduction of planktonic graptolites and other organisms. These results support the interpretation that the remains of organisms were quickly buried and that the amount of exchange between pore water and the water column gradually decreased. H2S gas generated by the decay of organisms during deposition consequently generated a strongly reducing environment in these sediments, which resulted in the formation of black shales.

Bacterial Surface Spreading Is More Efficient on Nematically Aligned Polysaccharide Substrates.

Biofilm-forming bacteria typically deposit layers of polysaccharides on the surfaces they inhabit; hence, polysaccharides are their immediate environment on such surfaces. Previously, we showed that many biofilm-forming bacteria preferentially spread in the direction of aligned and densely packed polysaccharide fibers in compressed substrates, a behavior we referred to as polymertropism. This arrangement of polysaccharide fibers is likely to be similar to that found in the "slime" trails deposited by many biofilm-forming bacteria and would explain previous observations that bacteria tend to follow these trails of polysaccharides. Here, we show that groups of cells or flares spread more rapidly on substrates containing aligned and densely packed polysaccharide fibers. Flares also persist longer, tend to hold their trajectories parallel to the long axes of polysaccharide fibers longer, and ultimately show an increase in displacement away from their origin. On the basis of these findings and others, we propose a model for polymertropism. Namely, we suggest that the packing of the aligned polymers increases the efficiency of surface spreading in the direction of the polymer's long axes; therefore, bacteria tend to spread more rapidly in this direction. Additional work suggests that bacteria can leverage polymertropism, and presumably more efficient surface spreading, for a survival advantage. In particular, when two bacterial species were placed in close proximity and in competition with each other, the ability of one species to move rapidly and directly away from the other by utilizing the aligned polymers of compressed agar substrates led to a clear survival benefit.IMPORTANCE The directed movement of bacteria on compressed substrates was first described in the 1940s and referred to as elasticotaxis (R. Y. Stanier, J Bacteriol 44:405-412, 1942). More recently, this behavior was referred to as polymertropism, as it seems to be a response to the nematic alignment and tight packing of polymers in the substrate (D. J. Lemon, X. Yang, P. Srivastava, Y. Y. Luk, A. G. Garza, Sci Rep 7:7643, 2017, https://doi.org/10.1038/s41598-017-07486-0). The data presented here suggest that bacteria are more efficient at surface spreading when the polymers in the substrate are arranged in this manner. These data also suggest that bacteria can leverage polymertropism, and presumably more efficient surface spreading, for a survival advantage. Namely, one bacterial species was able to use its strong polymertropism response to escape from and survive competition with another species that normally outcompetes it.

To improve alignment of isoindigo-based conjugated polymer film by controlling contact line receding velocity

The macroscopic alignment of conjugated polymers with low grain boundary is essential to carrier transport. During film forming process, the match between contact line receding velocity and the critical alignment velocity is essential to get the alignment polymer film. In this paper, the contact line receding velocity of a D-A conjugated polymer film, isoindigo and bithiophene (IIDDT-C3), was adjusted by solvent vapor content and film-formation temperature. Only when solvent vapor content was 0.3mL and the film-formation temperature was 90°C, the contact line receding velocity was in accordance with the critical alignment velocity, and the highest degree of alignment was attained in the IIDDT-C3 film, with the dichroic ratio up to 4.08. Fibers were aligned parallel with the direction of the contact line receding and the molecules of IIDDT-C3 adopted an edge-on orientation with the backbone parallel with the direction of fiber long axis. The π-π stacking distance between adjacent molecules was 3.63Å.

Shape‐Assisted Self‐Organization in Highly Disordered Liquid Crystal Phases

AbstractIn achiral rod‐like molecules, a nematic phase is the most disordered liquid crystal phase, which only has one‐directional order in the direction of the molecular long axis. A dumbbell‐shaped molecule (compound 3: R−C6H10−CH=CH−C6H4−CH=CH−C6H10−R, (R=nC5H11)), and its liquid crystal phase (X phase) are reported, which exhibit high scattering without thermal fluctuation between two nematic phases under a polarized light optical microscope. The X phase was investigated by X‐ray diffraction, scanning electron microscopy, atomic force microscopy, and molecular dynamics simulation. A layered structure was ascertained for which a molecular self‐organization mechanism was postulated in which the super‐structure is based on lateral intermolecular interlocking. A second nematic phase above the X phase consisted of “rice grain”‐shaped particles.

Shape-Assisted Self-Organization in Highly Disordered Liquid Crystal Phases.

In achiral rod-like molecules, a nematic phase is the most disordered liquid crystal phase, which only has one-directional order in the direction of the molecular long axis. A dumbbell-shaped molecule (compound 3: R-C6 H10 -CH=CH-C6 H4 -CH=CH-C6 H10 -R, (R=nC5 H11 )), and its liquid crystal phase (X phase) are reported, which exhibit high scattering without thermal fluctuation between two nematic phases under a polarized light optical microscope. The X phase was investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and molecular dynamics simulation. A layered structure was ascertained for which a molecular self-organization mechanism was postulated in which the super-structure is based on lateral intermolecular interlocking. A second nematic phase above the X phase consisted of "rice grain"-shaped particles.