Column Axis Research Articles

Chiral Self-Sorting and the Realization of Ferroelectricity in the Columnar Liquid Crystal Phase of an Optically Inactive N,N'-Diphenylurea Derivative Possessing Six (±)-Citronellyl Groups.

An axially polar-ferroelectric columnar liquid crystal (AP-FCLC) phase that exhibits both switching and maintenance of the macro-polarity in the column axis direction has been achieved in an N,N′-bis(3,4,5-trialkoxyphenyl)urea compound (rac-1) prepared from (±)-citronellyl bromide. Although it had been thought that chirality is necessary to achieve the AP-FCLC phase from our previous study, the optically inactive compound which is a mixture of 21 stereoisomers, generated an AP-FCLC phase. We confirmed its ferroelectricity and investigated the mechanism for realizing the AP-FCLC phase using optoelectronic experiments, X-ray diffraction, and circular dichroism spectroscopy. As a result, it was suggested that chiral self-sorting occurs in the columnar liquid crystal phase, in which molecules with a similar stereochemistry form a one-handed helical column, and columns with the same helicity gather together to form a chiral domain. Accordingly, we conclude that the optically inactive compound rac-1 also indicates ferroelectricity similar to that of an optically pure urea compound because of chiral self-sorting.

External Dynamic Apparatus Correction in Rigid Posttraumatic Spinal De-formations Engineering and Clinical Aspects

Study design: The authors define most dangerous sections and calculate the stresses arising in the parts of the external fixation device. They configure external fixation devices taking into account the obtained results and use them in medical practice. Objective: the development of an apparatus correction technique for the treatment of spinal deformations. Summary of background data: standard methods of rigid deformation correction are technically complicated and high-costly; there are also possible formidable intraoperative complications. Authors consider a variant of apparatus external correction as an alternative to the known methods, which is devoid of the aforementioned disadvantages. Methods: The authors use theoretical and experimental research methods. The theoretical deductions are confirmed experimentally during clinical trials. Clinical studies were evaluated using ray-based diagnostic procedures, computed tomography, and patient interviewing using the Oswestry Disability Index and visual analogue scale. Results: The calculations showed that in case of one-sided point load, the stresses arising in the dangerous section of screws-rods from that load can reach 60 – 70% of the total stresses in the device nodes. During clinical testing it was established that external apparatus correction leads to normalization of anatomical relationships in the area of damaged segments, normalization of the spinal column axis, and reduction of pain; it does not preclude the use of dorsal internal puncture fixation. Conclusions: It is advisable to load the structural element of the external spinal fixation device in a skew-symmetric pattern, applying distraction and compression forces to the transverse plate on both sides along parallel straight lines in opposite directions. Apparatus external fixation makes it possible to perform a complete correction of rigid deformations without releasing the supporting structures, to control the level of neurological dis-orders, to simplify the technique of internal fixation operations, to use the minimally invasive procedure for the installation of the internal pedicle fixator.

Experiments on the Hysteretic Response of Self-Centering RC Columns Prestressed by Unbonded Posttensioned Tendons

ABSTRACT The prestressed column, where unbonded posttensioned tendons are arranged along the axis of the RC column, showed self-centering behavior after lateral loading. To investigate the detailed hysteretic response, nine prestressed RC columns with different axial loads and transverse reinforcement arrangements were tested and subjected to the combined action of cyclic horizontal loading and constant axial loading. The experimental results revealed the failure modes, and the drift capacity was analyzed using the ductility and plastic hinge zone length. The controlling effects on residual displacements varied over time during testing, and their mechanism was explained from the point of view of energy dissipation capacity.

A single column plasma photonic crystal (SC-PPC)

In this paper, a reconfigurable one-dimensional single column plasma photonic crystal (SC-PPC) has been investigated. The SC-PPC is a glass column containing standing plasma density patterns (SPDPs) called plasma blobs, where its density varies sinusoidally along the column axis. It appears like a collinear array of the plasma blobs which is produced by having the critical combination of input RF power and gas pressure in a column. The numbers of blobs and plasma density can be controlled by RF power and gas pressure. The value of plasma density is measured for the different numbers of plasma blobs formation by using the experimental setup. These measured data are utilized in the modeling and simulation of SC-PPC for the photonic bandgap (PBG) analysis. The simulation outcomes reveal that the SC-PPC induces PBGs that can be reconfigured with plasma density, lattice constant, and numbers of plasma blobs. This paper explicitly investigates the PBG analysis by modeling two cases, where the plasma density Ne=2.45×1016 m−3 with five plasma blobs and Ne=9×1016 m−3 with six plasma blobs are considered. The obtained outcomes verify the reconfigurable characteristics of SC-PPC.

Numerical Simulation of Axial Pressure Bearing Capacity of Building Concrete Short Column Based on Finite Element Analysis

Based on the ANSYS finite element platform, considering the geometric parameters and calculation method of the short column Axis material of concrete building, a numerical model of the Axial bearing capacity of concrete building under the finite element analysis is established. On the basis of the model, the load displacement curves of concrete bearing concrete bearing short column Axial pressure under the characteristics of different straps are analyzed, the standard values are set, and the concrete compression strength is set. The concrete conditions and numerical model simulation are established. Feasibility analysis, Through the test results and its specific test content to judge, put forward the test results of the matching method and strategy, give a personal opinion and test description.

Detailed numerical study of the peak shapes of neutral analytes injected at high solvent strength in short reversed-phase liquid chromatography columns and comparison with experimental observations

We report on a numerical investigation of the different steps in the development of the spatial concentration profiles developing along the axis of a liquid chromatography column when injecting large relative volumes (>10 to 20% of column volume) of analytes dissolved in a high solvent strength solvent band as can be encountered in the second dimension (2D) column of a two-dimensional liquid chromatography (2D-LC) system. More specifically, we made a detailed study of the different retention and the axial band broadening effects leading to the double-headed peak shapes or strongly fronting peaks that can be experimentally observed under certain conditions in 2D-LC. The establishment of these intricate peak profiles is discussed in all its fine, mechanistic details. The effect of the volume of the column, the volume and the shape of the sample band, the retention properties of the analyte and the band broadening experienced by the analytes and the sample solvent are investigated. A good agreement between the simulations and the experimental observations with caffeine and methylparaben injected in acetonitrile/water (ACN/H2O) mobile phase with different injection volumes is obtained. Save the difference in dwell volume, key features of experimental and simulated chromatograms agree within a few %. The simulations are also validated against a number of simple mathematical rules of thumb that can be established to predict the occurrence of a breakthrough fraction and estimate the amount of breakthrough.

Exceptional dual fluorescent, excited-state intramolecular proton-transfer (ESIPT) columnar liquid crystals characterized by J-stacking and large Stokes shifts

Excited-State Intramolecular Proton-Transfer (ESIPT) fluorophores are emerging as promising future materials for electronic and biotechnological applications. ESIPT columnar (Col) liquid crystals (LCs) have been especially projected as the apt materials for advanced technological endeavors. But, there are hardly any explorations in this direction and thus, needing immediate attention. Herein we report on the synthesis, characterization, and ESIPT activity of a homologous series of novel phasmidic bis(N-salicylideneaniline) Col LCs. Optical microscopic, calorimetric and powder X-ray diffraction (XRD) studies evidence the occurrence of hexagonal columnar (Colh) phase having p6mm symmetry where the constituent slices result from the self-assembly of a pair of mesogens in a side-by-side manner facilitated by intense longitudinal π-π interactions. X-ray data confirm the absence of both directionally correlated tilting of the slices and transverse core-core interactions within the columns. Fluorescence probing clearly evidence the ESIPT occurring not only in DCM solution of the mesogens but also in their three-condensed states viz., solid, liquid crystal, and isotropic liquid phase; in general, two archetypal emission bands at ~430 nm (weak) and ~ 630 nm (strong) with large Stokes shifts (250–275 nm) of ESIPT phenomenon have been observed. The slow shift of emission maxima of the ESIPT fluorescence as a function of decreasing temperature without photoluminescence quenching coupled with the estimated tilt angle (ϴ) of the slices normal to the columnar axis (37 to 42o), from the XRD data, confirm the formation of so-called Scheibe or J-aggregates. The redox activity, metal ion sensing ability, and solvatochromism of the mesogens have also been investigated. The study suggests that these ESIPT Col LCs with band-gap of about 3 eV can be regarded as wide-bandgap semiconducting materials having the electronic characteristics falling between those of conventional semiconductors and insulators.

On the rotational–translational equilibrium in non-thermal argon plasmas at atmospheric pressure

This work examines the rotational–translational equilibrium in non-thermal, argon-based plasmas at atmospheric pressure. In particular, rotational temperatures (T rot) and neutral gas temperatures (T g) are compared along the axis of plasma columns sustained by either radiofrequency (RF) or microwave (MW) electromagnetic fields. Water vapours or N2 admixtures are added to the high-purity argon plasmas to record the rotational temperatures from the emission spectra of either the OH(A2Σ + − X2Π i ) or the N2 +(B2Σ u + − X2Σ g + ) rovibrational systems. T g values are also deduced from the line broadening of selected Ar emission lines using an hyperfine spectrometer. In the MW Ar/H2O plasma, T g decreases from ∼2100 K close to the wave launcher to ∼1600 K near the end of the plasma column, while T rot is mostly constant in the 1500 K range. In presence of N2 admixtures instead of water vapours, T g is higher by about 300 K (from ∼2400 K to ∼1900 K), while T rot decreases from ∼3200 K to ∼2750 K along the plasma column. A discrepancy between T g and T rot is also observed in the much colder RF plasmas with T g ∼ 400 K and T rot ∼ 515 K. Such departure from the rotational–translational equilibrium in both plasmas is ascribed to the influence of electrons competing with neutrals to impose their own temperature on the distribution of rotational levels of both ground and excited states.

The comparative study of analyzing the T-shaped and square-shaped concrete columns

This study aims to analyze how much changes in column shape effect have on the strength of the column structure. This calculation is comparing a square-shaped concrete column with two different axis of a T-shaped column. Each sample is compared in terms of 6 different column dimensions, however, the cross-sectional area within the three samples ( Square, T-shaped axis1 and 2) has remained constant. The concrete quality (fc') is kept at 30 MPa while the reinforcement area used 1% and 5%. Column calculation analysis is using Hognestad stress-strain diagram relationship and finite difference method. The result shows, the greater the reinforcement ratio, the greater the difference of Mn value and the smaller the difference of Pn value, of T-shaped and square column for each area. The same cross-sectional area does not necessarily lead to the same behavior of a T-shaped column with a different axis

Comprehensive Exploration and three-dimensional construction technology of water plug based on directional horizontal drilling caved column

The ordovician limestone water inrush accident occurred during the excavation of 8228 working face in Tashan Coal Mine, Tongmei Group. On the basis of comprehensive geophysical exploration above and below the well, in order to find out the development boundary of the water flowing subsided column and the distribution characteristics of the broken body filled in it, and to control the subsided column by Grouting, the development boundary, the influence zone, the cementation of the fractured body and the distribution characteristics of the water flowing subsided column are found out by means of multi-layer and multi-branch surface directional horizontal drilling speed logging, drilling fluid leakage, cuttings logging and logging while drilling, and combined with data statistical analysis. The length and short axis of the collapse column is 410m - 200m, and the broken area is mainly distributed in the right front of the driving head of the belt roadway near the water inrush roadway. The 3d geological modeling of the spatial structure and development characteristics of the collapse column is carried out by using SURPAC software, and the main passageway area, fracture area and secondary fracture area are divided according to the crushing degree of the collapse column filling material. In view of the different zones of the collapse column broken body, the directional horizontal drilling control technology and the three-dimensional block grouting technology are used to construct the separate zones of the grouting technology. The safe mining of the working face is finally realized by the comprehensive treatment of cutting the source and reinforcing the water-flowing collapse column. The comprehensive exploration and treatment technology of directional horizontal drilling multi-branch collapse column provides a good reference for other similar projects.

Strength, ductility, and energy dissipation capacity of RC column strengthened with CFRP strip under axial load

The experimental study aims to increase the axial load capacities of reinforced concrete (RC) columns with square cross-section by carbon fiber textile composite (CFRP) strips. The main purpose of the study is to develop a strengthening method that does not adversely affect displacement ductility ratios and energy dissipation capacities. Improved strengthening details have been applied to a square cross-section RC column with low axial load capacity, the low compressive strength of concrete, and the inadequate number of stirrups, which are not designed according to regulations. The main variables examined in this study are the CFRP strip width, the spacing of CFRP strips, the use of anchorage in the overlap zone at CFRP strips, and the placement of CFRP strips horizontally or vertically to the column axis. In line with this study, eleven reinforced concrete columns with dimensions of 150x150x500 mm were produced. The ultimate axial load capacity, initial stiffness, displacement ductility ratios, and energy dissipation capacities of the test specimens were evaluated. It was investigated how the variables in the experiments affected the behavior of the columns. The performances of the details developed for strengthening have been examined and interpreted.

Molecular orientation and electrical properties in tert‐butylated phthalocyanine thin film fabricated by uniaxial solution coating

AbstractMolecular orientation, molecular packing structure, and electrical properties of thermally stable phthalocyanine, tert‐butylated phthalocyanine (t‐BuPcH2) in the thin film fabricated by bar‐coating method were investigated. The XRD patterns indicated that the columns composed of t‐BuPcH2 molecules formed hexagonal structure, the axis of which was parallel to the bar‐sweep direction, and t‐BuPcH2 molecules were vertically aligned to the bar‐sweep direction. Uniaxially oriented thin films of t‐BuPcH2 were successfully fabricated on Si substrate covered with polyimide by bar‐coating method, and the field effect mobility of t‐BuPcH2 was estimated to be 1.32 × 10−4 cm2 V−1 s−1 at maximum. The field effect mobility parallel to the bar‐sweep direction was approximately three times higher than that perpendicular to the bar‐sweep direction due to high electrical conduction along the column axis of t‐BuPcH2.

Experimental investigation of damaged square short RC columns with low slenderness retrofitted by CFRP strips under axial load

The aim of this study is to develop the retrofitting details, which will increase axial ultimate load capacity, stiffness, displacement ductility ratios, and energy dissipation capacities of short reinforced concrete (RC) low-slenderness columns to avoid adverse effects on earthquake performance. The main variables examined in the experimental study are the Carbon Reinforced Fiber Polymer (CFRP) strip width used for retrofitting, the distance between CFRP strips, the use of the anchor at the overlap zone in the CFRP strips, and the placement of the CFRP strips horizontally or vertically to the column axis. For these purposes, eleven square short RC columns with a dimension of 150x150x500 mm (with low slenderness ratio: λ = 11.5) were produced. The columns were damaged up to 50% of their axial load carrying capacity, then retrofitted with CFRP strips in different ways. The short RC columns with low slenderness ratio were tested under monotonic axial loading until they failure. By obtaining the axial load–displacement graphs of the test specimens, the ultimate axial load capacity, initial stiffness value, displacement-ductility ratios, and energy dissipation capacities are calculated and interpreted. It has been found that the most successful retrofitting detail is obtained when CFRP strips are placed perpendicular to the column axis, and CFRP fan-type anchors are used in the strip overlap region.

Constituent Isomerism-Induced Quasicrystal and Frank–Kasper σ Superlattices Based on Nanosized Shape Amphiphiles

Naturally, subtle variations in the chemical structures of constituent molecules may significantly affect their multiscale spatial arrangements, properties, and functions. Deceptively simple spheri...

Generation of Axially Polar Ferroelectricity in a Columnar Liquid Crystal Phase by Introducing Chirality

AbstractAxially polar ferroelectric columnar liquid crystals (AP‐FCLCs) are materials in which the molecules are self‐organized into axially polar columns and exhibit switching and holding of their polar directions. If the polar directions along the columnar axis can be controlled by using a nanosized electrode, AP‐FCLCs have the potential to realize ultrahigh‐density memory devices. Though switching polarities in columnar liquid crystal phases have been studied by many scientists, it remains difficult to realize bistable switching. In this study, it is found that replacement of the normal alkyl groups (decyl groups) with chiral groups ((S)‐citronellyl groups) in an N,N’‐bis(3,4,5‐trialkoxyphenyl)urea realizes perfect ferroelectricity in the rectangular columnar liquid crystal phase, and it is confirmed that the phase is an AP‐FCLC phase. The differences in the properties and molecular packing structures between the achiral and chiral urea compounds are investigated. Furthermore, the mechanism for achieving ferroelectricity by introduction of the chiral alkyl chains is postulated.

Advanced steel brace with multistable hysteretic damping enhanced by a multilayered structure

Water wave impacts on jacket structures would result in heavy impulse loads, which induce strong vibrations because of the low damping characteristics of metallic members. In order to resist the wave-impact and suppress the vibration of structures, a novel steel brace that contains a multilayered multistable (MLMS) column is designed for an adjustable product of sufficient stiffness and high damping. According to finite element simulating, the initial stiffness of the MLMS column was almost same as that of the multistable steel column [1], but the energy dissipation was several times larger than that of this column. To understand the hysteresis mechanism of the MLMS column, we performed a hybrid analysis of multilayer lamination and mixed boundary buckling and noted: the soft layer of the MLMS column conducts the neutral axis and bending stiffness, which controls critical buckling load that decides the highness of the hysteresis loop; the eccentric end caps mediates the loading axis of the MLMS column, which induces in the increment of the postbuckling displacement that broadens the width of the hysteresis loop. So, the displacement-force hysteretic relation of the MLMS column can be effectually adjusted by the appropriate physical parameters of the soft layer and the end caps, which is validated by parameter analysis using FEM. Through FEM simulations, we studied a jacket structure assembled with dissipative braces containing MLMS column, which exhibited a several times increment in the decay rate of impact-induced vibration compared to that of the same jacket platform with existing dissipative columns [1]. This study demonstrated the MLMS column is an effective alternative for obtaining high structural stiffness and high damping in marine engineering.

CO2 absorption into aqueous diethanolamine solution with nano heavy metal oxide particles using stirrer bubble column: Hydrodynamics and mass transfer

Abstract In this research, the TiO2, ZnO, and ZrO2 nanofluids based on the DEA solution were provided exploiting the ultrasonic dispersion system to investigate the impact of the nano-particles on the CO2 absorption in a continuously stirred bubble column. The nano-particle concentration was determined in the range 0.01−0.10 wt%,. Bubble size distribution along column axis measurements was carried out using the high-speed digital camera. The influences of several factors such as CO2 partial pressure, solid loading, nanoparticle type, and stirring speed on the hydrodynamic characteristics and CO2 absorption performance were examined in detail. The presence of nanoparticles increased the gas holdup and interfacial area up to optimum value and then had a negligible effect. The stirrer speed increased the gas holdup and interfacial area up to optimum value and then decreased. Furthermore, the results showed that the adding nanoparticles in the range of 0.01−0.1 wt% increased CO2 absorption efficiency between 25.2–43.8% and the optimum value of nanoparticles can be an effective key parameter at the absorption phenomena into a dilute amine solution. Also, it was determined that at optimum stirrer speed, the removal efficiency of ZnO, TiO2, and ZrO2 nanofluids was caused an increase of about 12.1 % 8.0 %, and 13.3 %, respectively.

Seismic failure analysis of concrete bridges exposed to scour

Scouring has been known as one of the most frequent cause of failure observed in bridge infrastructures. Not to mention, the evaluation of scour mechanism sheds light on pile foundation design and helps to prevent scour induced structural deficiencies. Thus, the scouring mechanism around bridge pile foundations should be extensively evaluated in order to predict the bridge safety under critical multi-hazard environment. In this study, the local scour mechanism around bridge piles was appraised considering discrete element methods (p-y curves) in order to reflect the nonlinear nature of soil structure interaction (SSI). Following that, bridge seismic behavior and relevant failure mechanism was evaluated with regard to nonlinear time history analyses (THA). In the conducted research, river crossing 7 – span Boğaçay Bridge located in Antalya, Turkey was selected as the case study. After SAP2000 finite element modeling (FEM), the bridge was exposed to twelve incremental scour depths up to six meters at all piers and was subject to subsequent seismic effects as concordant to the site that mimics a probable earthquake occurs after scouring regarding the Turkish Earthquake Code (TEC-2018). The modal responses indicated a simultaneous increase in natural periods with augmenting scour depth. In the analyses, the influence of scouring on pier displacement demands, pier accelerations and the internal forces at piers and piles were investigated. The analysis results indicated a significant increase in pier displacement demands with increasing scour depth especially in the transverse direction of the bridge. Further, due to the migration and spreading of plastic hinging from piers to piles due to scouring, the internal forces that were resisted by the strong axis of the pier columns decreased significantly. This fact led to the increase in pile bending moments and rotations in both orthogonal directions of the bridge. Thus, it was concluded that the probable multi-hazard effects of scouring and earthquake in river crossing bridges should be considered in bridge substructure design.

A study on solution-processable tetrabenzomonoazaporphyrin hole transport material for pervoskite solar cells

We demonstrate optical and electronic properties and structure of an efficient hole transporting material (HTM), soluble non-peripherally substituted octahexyl tetrabenzomonoasaporphyrin (C6TBMAPH2), for perovskite solar cells (PSCs). X-ray diffraction patterns of C6TBMAPH2 thin film with two peaks at around 4.6° and 4.9° indicate that the symmetry of columns is likely to be 2-dimensional rectangular lattice and stacking period of molecules along columnar axis may be disordered. The absorption spectra of C6TBMAPH2 exhibit the two predominated bands at around 400 and 650 nm, which correspond to the B and Q bands, respectively. Furthermore, the electronic band structure of C6TBMAPH2, was calculated with highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of −5.0 and −3.3 eV, respectively. All results suggest that C6TBMAPH2 could be one potential HTM to extract hole and block electron from the absorber to the back electrode. Finally, an efficient solid-state, thin-film PSC utilising C6TBMAPH2 HTM is fabricated with the best PCEs of 4.9 and 5.6% under forward and reverse bias scans, respectively.

Strikingly different molecular organization and molecular order of tetracatenar mesogens in columnar mesophases revealed by XRD and 13C NMR.

For a successful design of functional mesogens, it is paramount to understand factors that contribute to molecular organisation such as molecular shape, the non-covalent interactions of the constituent moieties as well as nanosegregation of incompatible molecular parts. In this study on four tetracatenar mesogens, we show that by a slight change in the length of the terminal chain, the molecular organization changes from lamellar to columnar phase and that the orientational order experiences profound change between the lamellar, the center rectangular columnar and the hexagonal columnar mesophases. We consider here, mesogens that exhibit lamellar and columnar mesophases with five phenyl rings in the central rod-like core which are subjected to XRD and high resolution solid state 13C NMR investigations in their mesophases. The XRD studies indicate that the lower homologs exhibit a lamellar mesophase while the higher homologs show either a centre rectangular columnar phase or a 2D hexagonal columnar mesophase. 13C NMR investigations reveal interesting and strikingly different molecular orientations in each of these phases. For example, values of order parameters of one of the phenyl rings in the core region of the mesogens vary from 0.75 and 0.77 for the lamellar mesogens to 0.45 and 0.17 for the centre rectangular columnar and the hexagonal columnar mesogens respectively. While these values indicate that the mesogenic molecules are oriented along the magnetic field as expected in the lamellar phases, the very low order parameter in the hexagonal columnar phase arises due to molecules distributed azimuthally in layers and undergoing motion about the columnar axis which itself is oriented orthogonal to the magnetic field. Such cutting edge information extracted from the combined use of XRD and 13C NMR studies on tetracatenar mesogens is expected to be of significant use for the study of π-conjugated polycatenar systems where functional properties depend on the molecular orientation and order.