Longer Rods Research Articles

Dielectric coated conductive rod resonantly coupled with a cut transmission line as a tunable microwave bandstop filter and sensor

The resonant interaction of a dielectric-coated conductive rod with the X-band microwave field is investigated. The magnetic field distribution of the Goubau standing radial surface waves was experimentally visualized by using a thermo-elastic optical indicator microscope, and the corresponding electric field distribution was determined via numerical simulations. These field distributions are characterized by a certain pattern of antinodes distinctive for standing waves. An analysis of these field distributions allows one to couple a coated rod with a cut Goubau line. A rod placed in the gap region perpendicular to the Goubau line results in a sharp rejection band in the transmission spectrum which is extremely sensitive to the changes in the surrounding media. The shifting rate of the resonance as a function of the dielectric shell thickness is approximately 1.4 GHz/mm. The Q-factor of copper rods depends on their size and dielectric shell thickness. Longer rods with more energy localization areas have higher Q-factors, typically 1.7 times higher (12.7 vs. 7.5). Moreover, incorporating a dielectric shell enhances energy confinement and can elevate the Q-factor by as much as 22 %. When a 25 mm Cu rod is situated inside a cut Goubau line system, the Q-factor values are significantly higher, with a ratio of 275 to 13. With the addition of a dielectric shell, the Q-factor can be elevated by 58 %. The versatility of the proposed controllable system makes it possible to tune the operating spectrum towards higher GHz and THz frequencies.

Orientational ordering of polydisperse nanorods on a flat surface

The use of two-dimensional liquid crystals (2D LCs) made of carbon nanorods has become increasingly popular in electronic, optical, and energy applications due to their unique properties. However, the orientational ordering of such liquid crystals remains poorly understood. Here, we model of 2D LCs using the length polydisperse hard needle model and apply theOnsager theory to explore the impact of length polydispersity on nematic ordering. Our results show that length polydispersity plays a crucial rolein stabilizing the nematic phase over the isotropic phase, albeit at the expense of weaker orientational ordering. Longer rods, in particular, contribute to the stabilization of the nematic phase, whereas shorter rods result in weaker nematic ordering. To achieve a highly ordered 2D nematic phase, the polydispersity of the nanorods must be reduced.

Nanorod length-dependent photodriven H2 production in 1D CdS-Pt heterostructures.

Colloidal quantum confined semiconductor-metal heterostructures are promising candidates for solar energy conversion because their light absorbing semiconductor and catalytic components can be independently tuned and optimized. Although the light-to-hydrogen efficiencies of such systems have shown interesting dependences on the morphologies of the semiconductor and metal domains, the mechanisms of such dependences are poorly understood. Here, we use Pt tipped 0D CdS quantum dots (with ∼4.6nm diameter) and 1D CdS nanorods (of ∼13.8, 27.8, 66.6, and 88.9nm average rod lengths) as a model system to study the distance-dependence of charge separation and charge recombination times and their impacts on photo-driven H2 production. The H2 generation quantum efficiency increases from 0.2% ± 0.0% in quantum dots to 28.9% ± 0.4% at a rod length of 28nm and shows negligible changes at longer rod lengths. The half-life time of electron transfer from CdS to Pt increases monotonically with rod length, from 0.7 ± 0.1 in quantum dots to 170.2 ± 29.5ps in the longest rods, corresponding to a slight decrease in electron transfer quantum efficiency from 92% to 81%. The amplitude-weighted average lifetime of charge recombination of the electron in Pt with the hole in CdS increases from 4.7 ± 0.4 µs in quantum dots to 149 ± 34 µs in 28nm nanorods, and the lifetime does not increase further in longer rods, resembling the trend in the observed H2 generation quantum efficiency. Our result suggests that the competition of the charge recombination process with the hole removal by the sacrificial electron donor plays a dominant role in the observed nanorod length dependent overall light driven H2 generation quantum efficiency.

Bismuth sulfide nanorods by thermal decomposition of a complex: Effect of reaction temperature on microstructural and optical properties

Bismuth sulfide nanorods have been prepared by thermolysis of a bismuth dithiocarbamate complex, as a single-source precursor, in a mixture of solvents (oleylamine, 1-dodecanethiol, and 1-octadecene) at various temperatures. Bismuth sulfide nanorods denoted as BS(120), BS(150), BS(180), BS(200), and BS(220) have been obtained at the specified temperatures (°C). They have been characterized by X-ray diffraction analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV/Vis spectrophotometry, and photoluminescence (PL) spectroscopy. The effect of temperature on the microstructural and optical properties of the obtained Bi2S3 has been studied. The results show that interactions of the N–H group of oleylamine and the S–H group of dodecanethiol with the nanoparticles are temperature-dependent. The crystallite sizes of the nanoparticles were calculated using the Scherrer equation, Williamson–Hall (W–H) analysis, and Rietveld analysis, which yielded values in the ranges 20.1–45.9, 20.9–26.6, and 23.0–29.6 nm, respectively. Analysis of the microstrain in crystals of the nanoparticles showed that while the strain therein was due to contraction of the nanoparticles obtained at 180 °C, the strains at other temperatures were due to expansion, thereby confirming the effect of temperature on the nature of the defects in Bi2S3 crystals. The lattice strains were estimated by the W–H and Rietveld analyses to be in the ranges 3.19 × 10−5–1.04 × 10−4 and 0.008–0.067, respectively. The crystallite sizes and lattice strains estimated by both W–H and Rietveld analyses were mutually consistent, showing similar trends. SEM and TEM analyses showed that the nanorods were aggregated into longer rods at 120 and 150 °C, whereas shorter rods were obtained at 180 and 220 °C, suggesting a change in preferential growth direction. The widths and lengths of the nanorods were estimated as 20.97–41.25 nm and 79.4–111.0 nm, respectively, giving aspect ratios in the range 1.92–5.52. The band-gap energies of the nanorods varied in the range 1.08–0.78 eV, which can be related to differences in tail state width as observed in the absorption spectra. Calculation of texture coefficients showed preferential growth in the (111), (020), and (321) directions.

Synthesis of tunable near infrared absorbance of gold nanorods (AuNRs) and their gold oxidation states during nanorod formation following by synchrotron based X-ray absorption spectroscopy (XANES)

A study of growth mechanism on AuNRs synthesized using seed-mediated method has been conducted via time resolved synchrotron based XAS. The synthesized AuNRs were characterized by TEM and UV–vis spectroscopy. It was found that the volume change of AgNO3 solution influenced their surface plasmon resonances (SPR) of AuNRs. An increase of silver ions concentration resulted in an increase of the aspect ratio (AR). For the growth mechanism investigation, time-resolved XANES in fluorescent mode and UV–vis measurement were employed. The potential growth mechanism was proposed according to the XANES spectrums. The reduction of Au(3+) oxidation state to Au(0) occurs after the reducing agent were added. The change in oxidation state of the AuNRs corresponded to the XANES spectrum of AuCl illustrating the oxidation states were reduced from Au(3+) to Au(+) then Au(0), respectively. Moreover, the rate of change in oxidation state depended on the AR. The formation of AuNRs was completed for the shorter rods (AR∼2.0) while the longer rods (AR∼4.2) still exhibit higher feature of oxidation state compared at the same reaction time. In addition, the change in absorbance from UV–vis spectrums revealed that AuNRs with AR∼2.0 took 50 min to complete rod formation which is faster than that of the AuNRs with AR∼4.2 (60 min). These UV–vis results were in a good agreement with the XANES spectrums. This finding leaded to conclude that the rod formation of AuNRs with lower AR could occurred faster than the formation of AuNRs with higher AR.

The lexicon of multirod constructs in adult spinal deformity: a concise description of when, why, and how.

The use of multirod constructs in the setting of adult spinal deformity (ASD) began to prevent rod fracture and pseudarthrosis near the site of pedicle subtraction osteotomies (PSOs) and 3-column osteotomies (3COs). However, there has been unclear and inconsistent nomenclature, both clinically and in the literature, for the various techniques of supplemental rod implantation. In this review the authors aim to provide the first succinct lexicon of multirod constructs available for the treatment of ASD, providing a universal nomenclature and definition for each type of supplementary rod. The primary rod of ASD constructs is the longest rod that typically spans from the bottom of the construct to the upper instrumented vertebrae. The secondary rod is shorter than the primary rod, but is connected directly to pedicle screws, albeit fewer of them, and connects to the primary rod via lateral connectors or cross-linkers. Satellite rods are a 4-rod technique in which 2 rods span only the site of a 3CO via pedicle screws at the levels above and below, and are not connected to the primary rod (hence the term "satellite"). Accessory rods are connected to the primary rods via side connectors and buttress the primary rod in areas of high rod strain, such as at a 3CO or the lumbosacral junction. Delta rods span the site of a 3CO, typically a PSO, and are not contoured to the newly restored lordosis of the spine, thus buttressing the primary rod above and below a 3CO. The kickstand rod itself functions as an additional means of restoring coronal balance and is secured to a newly placed iliac screw on the side of truncal shift and connected to the primary rod; distracting against the kickstand then helps to correct the concavity of a coronal curve. The use of multirod constructs has dramatically increased over the last several years in parallel with the increasing prevalence of ASD correction surgery. However, ambiguity persists both clinically and in the literature regarding the nomenclature of each supplemental rod. This nomenclature of supplemental rods should help unify the lexicon of multirod constructs and generalize their usage in a variety of scientific and clinical scenarios.

Effect of Comb-Type Copolymers on the Non-Isothermal Crystallization Behavior of Paraffin in Methyl Ethyl Ketone (MEK)–Toluene Dewaxing

Two comb-type copolymers were synthesized by modifications of the maleic anhydride-α-octadecene copolymer with aniline (AMAC) and with phenethylamine (EMAC), respectively. The effects of AMAC and EMAC on the non-isothermal crystallization kinetics of the MEK–toluene dewaxing process were comparatively investigated. The results showed that, under the optimum process conditions, the addition of 100 ppm AMAC or EMAC could increase the yield of dewaxed oil (DWO) from 67.21% to 70.87% or 69.90%, respectively, and increase the filtration rate by 80% and 70%, respectively. The non-isothermal crystallization kinetics analysis showed that the crystallization process conformed to Mo’s equation, and the addition of AMAC and EMAC slowed down the crystallization rate of paraffin. The polarizing light microscope observations revealed that the addition of AMAC promoted the formation of snow flower-like crystals, and the EMAC addition led to the crystals having longer rods with a relatively complete morphology. This work provided useful experimental data for a better understanding of the roles of comb-type copolymer additives in the MEK–toluene dewaxing process.

VALUATION OF DURABILITY OF ROD PILLARS OF THE SLOPY RESCUING DEVICE

The need for special saving devices arises during emergency response. Such situations are connected with rescuing of people or animals from deep narrow holes or even from under blockages of constructions. By using the saving devices the cargo raising on a certain height is possible if other ways of delivery are absent. Main structural elements of saving devices are three rod pillars. Top ends of rods are connected in a mounting knot. Often the saving device is equipped with the winch. The winch could be fasten to one of the rod pillars or have individual placing. Rescuing devices differ in a type of a rod design (straight or a slopy plane), loading capacity, rods production material, type of rods connection, a possibility of using on slopes with pillars location in the different planes, modifications of winches, compactness during transportation. There is a big variety of rescuing devices, however in the market of Ukraine offer mostly straight rod rescuing devices. Therefore there is a need for creation of design and durability checking of the slopy rod rescuing device which could be applied to carrying out rescue operations from bridges, buildings and other constructions. In this work it is performed an estimation of durability of a design of the slopy rod rescuing device. It is considered three cases of the support pillars placement. The first case is when pillars of the slopy rescuing device are placed in one horizontal plane. The second case - the longest rod pillar is placed on a ledge. The third case - two shorter rod pillars are placed on a ledge. For each of these cases it is established a type of deformation of rods of the saving device. Construction rods are stretching or compression during work are and loaded with longitudinal forces. From the stretching durability condition the cross section of steel rods is picked up.

Sequential Symmetry-Breaking Intercolumnar Transformations of a Conjugated Rod Molecule with a Flexible Coil

In this paper, we report distinct symmetry-breaking phase transitions in molecules based on oligo-para-phenylene rods and a poly(ethylene oxide) coil depending on the length of the aromatic rod block The observed phase transitions were characterized by differential scanning calorimetry (DSC) and X-ray scattering methods. Compound 1 with a tetra-para-phenylene rod exhibited a symmetry breaking intercolumnar transition from p2gg to p6mm symmetry. This phase transition was accompanied by an endothermic peak in the DSC profile (first-order transition), suggesting an in-plane twist of the ribbon-like rod domain. On the other hand, 2 with a longer penta-para-phenylene rod exhibited sequential symmetry breaking intercolumnar transitions from c2mm to p2gg to p6mm symmetry. In contrast with 1, the phase transitions were accompanied by no enthalpy change. Therefore, the ribbon-like rod domains were not segmented due to increased inter-rod interactions of the longer aromatic rods. The phase transitions of 2 are attributed to increased thermal motions of the coils, which vary the orientational angle of the aromatic columns in the lattice.

Dependence of the Spontaneous Luminescence Intensity in ZnO Nanorods on their Length

The influence of the length of ZnO nanorods (500 nm in diameter) on the mode structure and spontaneous luminescence in the ultraviolet spectral region is studied by optical luminescence microscopy. It is shown that individual nanorods with a metal mirror on one face exhibit only two or three laser modes in the case of short nanocavity lengths (8–30 μm). Different values of the optical losses of the longitudinal and transverse waveguide modes are established for a ZnO nanorod lying on a glassy substrate. The quadratic dependence of the spontaneous luminescence intensity on the rod length can be attributed to improvement of the optical quality factor Q of bound longitudinal modes of light within longer rods (the Purcell effect).

Зависимость интенсивности спонтанной люминесценции наностержней ZnO от их длины

AbstractThe influence of the length of ZnO nanorods (500 nm in diameter) on the mode structure and spontaneous luminescence in the ultraviolet spectral region is studied by optical luminescence microscopy. It is shown that individual nanorods with a metal mirror on one face exhibit only two or three laser modes in the case of short nanocavity lengths (8–30 μm). Different values of the optical losses of the longitudinal and transverse waveguide modes are established for a ZnO nanorod lying on a glassy substrate. The quadratic dependence of the spontaneous luminescence intensity on the rod length can be attributed to improvement of the optical quality factor Q of bound longitudinal modes of light within longer rods (the Purcell effect).

Stress distribution in vertebral bone and pedicle screw and screw–bone load transfers among various fixation methods for lumbar spine surgical alignment: A finite element study

This paper examines the stress distribution in the posterior fusion fixation, spinal range of motion (ROM), and the screw–bone interaction force obtained from various fixation methods of short-segment spine surgical alignment (SA) under five loading conditions (axial compression, flexion, extension, lateral bending, and axial rotation) provided by a FE spine model. The implant-instrumented FE spine model was validated against the experimental data in the literature. Among different fixation methods, fusing more spinal segments might help distribute the spinal load on the pedicle-screw to reduce the stress, screw force, and instability of the spine (range of motion). With longer rods, the additional intermediate screws are suggested to provide additional anchoring effect to the fixation device. However, the fact that inserting more screws also increases the stress concentration points on the rods should also be considered. Further this study supports the clinical observation that interbody cage can provide anterior support to the spine and reduce the loads on the posterior fixation devices. In both single-level and two-level fusion, IB reduced ROM, rod stress, and screw/bone interaction force.

Self assembly of cyclic polygon shaped fluid colloidal membranes through pinning.

2D fluid monolayer membranes of rod-like viruses spontaneously form in a mixture of rods and polymers through depletion attraction. The rods are uniformly oriented within the bulk and twist in a zone around the membrane edge. Surprisingly, we find that cyclic polygonal shaped colloidal membranes form when polymers are added to a mixture of long and short-thick rods with the long and short-thick rods forming the faceted core and lobes of the polygon, respectively. We demonstrate that the origin of this anisotropic shape lies in the phenomenon of spreading of one liquid over another in the presence of disorder. As a membrane of short-thick rods spreads over another of longer rods, the edge bound rods untwist to become part of the newly formed two-rod interface. However, a small fraction of rods fail to untwist as the two rod interface forms and act as mobile pinning centers. Capillary flow of short-thick rods drives all the pinning centers to a single location in the composite membrane which now acts like a junction. This pinning junction inhibits complete engulfing of one membrane by the other. Repeated sequential events like this then lead to formation of multiple junctions and the overall cyclic polygon topology. We find that pinning junctions are weakly cross-linked in nature instead of being topological defects. We outline the necessary and sufficient constraints on the nature of rods to obtain stable out of equilibrium cyclic polygon membranes. Our results show a unique counter-intuitive scenario where defects lead to self-assembly of ordered structures.

Influence of the connecting condition on the dynamic buckling of longitudinal impact for an elastic rod

The stress wave propagation law and dynamic buckling critical velocity are formulated and solved by considering a general axial connecting boundary for a slender elastic straight rod impacted by a rigid body. The influence of connecting stiffness on the critical velocity is investigated with varied impactor mass and buckling time. The influences of rod length and rod mass on the critical velocity are also discussed. It is found that greater connecting stiffness leads to larger stress amplitude, and further results in lower critical velocity. It is particularly noteworthy that when the connecting stiffness is less than a certain value, dynamic buckling only occurs before stress wave reflects off the connecting end. It is also shown that longer rod with larger slenderness ratio is easier to buckle, and the critical velocity for a larger-mass rod is higher than that for a lighter rod with the same geometry.

Cellular Uptake and Movement in 2D and 3D Multicellular Breast Cancer Models of Fructose-Based Cylindrical Micelles That Is Dependent on the Rod Length.

While the shape effect of nanoparticles on cellular uptake has been frequently studied, no consistent conclusions are available currently. The controversy mainly focuses on the cellular uptake of elongated (i.e., filaments or rod-like micelles) as compared to spherical (i.e., micelles and vesicles) nanoparticles. So far, there is no clear trend that proposes the superiority of spherical or nonspherical nanoparticles with conflicting reports available in the literature. One of the reasons is that these few reports available deal with nanoparticles of different shapes, surface chemistries, stabilities, and aspects ratios. Here, we investigated the effect of the aspect ratio of cylindrical micelles on the cellular uptake by breast cancer cell lines MCF-7 and MDA-MB-231. Cylindrical micelles, also coined rod-like micelles, of various length were prepared using fructose-based block copolymers poly(1-O-methacryloyl-β-d-fructopyranose)-b-poly(methyl methacrylate). The critical water content, temperature, and stirring rate that trigger the morphological transition from spheres to rods of various aspect ratios were identified, allowing the generation of different kinetically trapping morphologies. High shear force as they are found with high stirring rates was observed to inhibit the formation of long rods. Rod-like micelles with length of 500-2000 nm were subsequently investigated toward their ability to translocate in breast cancer cells and penetrate into MCF-7 multicellular spheroid models. It was found that shorter rods were taken up at a higher rate than longer rods.

Joint-Angle Coordination Patterns Ensure Stabilization of a Body-Plus-Tool System in Point-to-Point Movements with a Rod.

When performing a goal-directed action with a tool, it is generally assumed that the point of control of the action system is displaced from the hand to the tool, implying that body and tool function as one system. Studies of how actions with tools are performed have been limited to studying either end-effector kinematics or joint-angle coordination patterns. Because joint-angle coordination patterns affect end-effector kinematics, the current study examined them together, with the aim of revealing how body and tool function as one system. Seated participants made point-to-point movements with their index finger, and with rods of 10, 20, and 30 cm attached to their index finger. Start point and target were presented on a table in front of them, and in half of the conditions a participant displacement compensated for rod length. Results revealed that the kinematics of the rod's tip showed higher peak velocity, longer deceleration time, and more curvature with longer rods. End-effector movements were more curved in the horizontal plane when participants were not displaced. Joint-angle trajectories were similar across rod lengths when participants were displaced, whereas more extreme joint-angles were used with longer rods when participants were not displaced. Furthermore, in every condition the end-effector was stabilized to a similar extent; both variability in joint-angle coordination patterns that affected end-effector position and variability that did not affect end-effector position increased in a similar way vis-à-vis rod length. Moreover, the increase was higher in those conditions, in which participants were not displaced. This suggests that during tool use, body and tool are united in a single system so as to stabilize the end-effector kinematics in a similar way that is independent of tool length. In addition, the properties of the actual trajectory of the end-effector, as well as the actual joint-angles used, depend on the length of the tool and the specifics of the task.

Density and Shape Effects in the Acoustic Propulsion of Bimetallic Nanorod Motors

Bimetallic nanorods are propelled without chemical fuels in megahertz (MHz) acoustic fields, and exhibit similar behaviors to single-metal rods, including autonomous axial propulsion and organization into spinning chains. Shape asymmetry determines the direction of axial movement of bimetallic rods when there is a small difference in density between the two metals. Movement toward the concave end of these rods is inconsistent with a scattering mechanism that we proposed earlier for acoustic propulsion, but is consistent with an acoustic streaming model developed more recently by Nadal and Lauga ( Phys. Fluids 2014 , 26 , 082001 ). Longer rods were slower at constant power, and their speed was proportional to the square of the power density, in agreement with the acoustic streaming model. The streaming model was further supported by a correlation between the disassembly of spinning chains of rods and a sharp decrease in the axial speed of autonomously moving motors within the levitation plane of the cylindrical acoustic cell. However, with bimetallic rods containing metals of different densities, a consistent polarity of motion was observed with the lighter metal end leading. Speed comparisons between single-metal rods of different densities showed that those of lower density are propelled faster. So far, these density effects are not explained in the streaming model. The directionality of bimetallic rods in acoustic fields is intriguing and offers some new possibilities for designing motors in which shape, material, and chemical asymmetry might be combined for enhanced functionality.

Shape effects on dynamics of inertia-free spheroids in wall turbulence

The rotational motion of inertia-free spheroids has been studied in a numerically simulated turbulent channel flow. Although inertia-free spheroids were translated as tracers with the flow, neither the disk-like nor the rod-like particles adapted to the fluid rotation. The flattest disks preferentially aligned their symmetry axes normal to the wall, whereas the longest rods were parallel with the wall. The shape-dependence of the particle orientations carried over to the particle rotation such that the mean spin was reduced with increasing departure from sphericity. The streamwise spin fluctuations were enhanced due to asphericity, but substantially more for prolate than for oblate spheroids.

Perception of Object Length Via Manual Wielding in Children With and Without Developmental Coordination Disorder

ABSTRACTThe authors compared haptic perception via active manual wielding in children with and without developmental coordination disorder (DCD). Forty-eight children, 11–12 years old, participated as volunteers. Twenty-four were typically developing children (TDC), and 24 had been diagnosed with DCD. Individually, children held and wielded unseen rods of five lengths (20, 45, 60, 75, or 90 cm). Based on this wielding, children judged the length of each rod. Judgments of rod length were shorter in the DCD group than in the TDC group. In addition, significant interactions revealed that the difference between the 2 groups was progressively greater for longer rods. The results provide support for the hypothesis that DCD includes deficits in the ability to use manual wielding in the perception of object length. In addition, the results suggest that the deficit is not general, but is greater for longer objects.

Glutamine deprivation initiates reversible assembly of mammalian rods and rings.

Rods and rings (RR) are protein assemblies composed of cytidine triphosphate synthetase type 1 (CTPS1) and inosine monophosphate dehydrogenase type 2 (IMPDH2), key enzymes in CTP and GTP biosynthesis. Small-molecule inhibitors of CTPS1 or IMPDH2 induce RR assembly in various cancer cell lines within 15 min to hours. Since glutamine is an essential amide nitrogen donor in these nucleotide biosynthetic pathways, glutamine deprivation was examined to determine whether it leads to RR formation. HeLa cells cultured in normal conditions did not show RR, but after culturing in media lacking glutamine, short rods (<2 μm) assembled after 24 h, and longer rods (>5 μm) formed after 48 h. Upon supplementation with glutamine or guanosine, these RR underwent almost complete disassembly within 15 min. Inhibition of glutamine synthetase with methionine sulfoximine also increased RR assembly in cells deprived of glutamine. Taken together, our data support the hypothesis that CTP/GTP biosynthetic enzymes polymerize to form RR in response to a decreased intracellular level of glutamine. We speculate that rod and ring formation is an adaptive metabolic response linked to disruption of glutamine homeostasis.