Rod Length Research Articles

Mutagenic analysis of the bundle-shaped phycobilisome from Gloeobacter violaceus.

Gloeobacter violaceus is an ancient cyanobacterium as it branches out from the basal position in the phylogenic tree of cyanobacteria. It lacks thylakoid membranes and its unique bundle-shaped type of phycobilisomes (PBS) for light harvesting in photosynthesis are located on the interior side of cytoplasmic membranes. The PBS from G. violaceus have two large linker proteins that are not present in any other PBS, Glr2806, and Glr1262, which are encoded by the genes glr2806 and glr1262, respectively. The location and functions of the linkers Glr2806 and Glr1262 are currently unclear. Here, we report the studies of mutagenetic analysis of glr2806 and the genes of cpeBA, encoding the β and α subunits of phycoerythrin (PE), respectively. In the mutant lacking glr2806, the length of the PBS rods remains unchanged, but the bundles are less tightly packed as examined by electron microscopy with negative staining. It is also shown that two hexamers are missing in the peripheral area of the PBS core, strongly suggesting that the linker Glr2806 is located in the core area instead of the rods. In the mutant lacking the cpeBA genes, PE is no longer present and the PBS rods have only three layers of phycocyanin hexamers. The construction of deletional mutants in G. violaceus, achieved for the first time, provides critical information for our understanding of its unique PBS and should be useful in studies of other aspects of this interesting organism as well.

Predictive Model of a Mole-Type Burrowing Robot for Lunar Subsurface Exploration

In this work, a dynamic model is proposed to simulate the drilling and steering process of an autonomous burrowing mole to access scientific samples from the deep subsurface of the Moon. The locomotive module is idealized as a rigid rod. The characteristic parameters are considered, including the length, cross-section diameter, and centroid of a cylindrical rod. Based on classical Lagrangian mechanics, a 3-DOF dynamic model for the locomotion of this autonomous device is developed. By introducing resistive force theory, the interaction scheme between the locomotive body and the lunar regolith is described. The effects of characteristic parameters on resistive forces and torques are studied and discussed. Proportional-derivative control strategies are introduced to calculate the tracking control forces following a planned trajectory. The simulation results show that this method provides a reliable manipulation of a mole-type robot to avoid obstacles during the tracking control process in layered sediments. Overall, the proposed reduced-order model is able to simulate the operating and controlling scenarios of an autonomous burrowing robot in lunar subsurface environments. This model provides intuitive inputs to plan the space missions of a drilling robot to extract subsurface samples on an extraterrestrial planet such as the Moon or Mars.

Flow field analysis of long rod hypervelocity penetration into semi-infinite concrete target

An ovoid of Rankine was used to describe the flow field shape, and a flow field analysis model was constructed to depict the penetration process. The depth of penetration, tunnel radius, change in the long rod length, and penetration velocity was calculated using this model. The calculation results were in good agreement with experimental data from previous studies. The influence of long rod material parameters on penetration was also analyzed. The following results were obtained: the depth of penetration increased slowly with increasing impact velocity at hypervelocity penetration, the erosion rate of the long rod was constant during the penetration process, and the length of the long rod was the most sensitive parameter affecting the depth of penetration, and the hole radius and long rod diameter had an approximately linear relationship and both increased with rod density.

Chemical, surface, and thermal studies of mixed oxides cupric oxide (CuO), lanthanum oxide (La2O3), and graphene oxide for dye degradation from aqueous solution

Mixed oxy-compositions are lately used for water treatment that might be exploited as photo-catalyst, and adsorptive materials for the disposal of water pollutants. Cupric oxide (CuO), lanthanum oxide (La2O3), and graphene oxide (GO)-based nanocomposites show an interest in water treatment applications owing to the adsorptive feature of carbon-based nanoparticles (NPs), besides low band gap of metal oxides that boosts photo-catalytic process. CuO/La2O3/GO-based nanocomposites are prepared and tested for their thermal stability, and dye removal activity. The change in nanocomposites structure upon the incorporation of CuO and La2O3 into GO nanosheets is inspected via TEM micrographs showing a decline in lanthana rod length to be 200 nm on average. Additionally, the improved roughness structure and the compact grain size appear in SEM micrographs reports CuO grain size reduction reaching an average size of 250 nm. The roughness parameters of CuO/La2O3/GO are extraordinarily heightened in which the supreme value of roughness average is 7.6 nm. Ternary nanocomposite exhibits a maximum value (85%) as a methylene blue (MB) dye removal. Based on these obtained results, the fabricated nanocomposites are recommended for water treatment due to their enriched physicochemical and morphological features as well as the better thermal stability and exerted dye removal activity.

Comb-forming roller with elastic rods

A design diagram of comb formation roller in resilient stems is given. Comb-forming roller consists of support and small discs, as well as elastic rods. Elastic rods are installed along the perimeter of the diameter of the disks through their holes. Analytical dependences and mathematical models are obtained for determining the distance between disks, the diameter of disks, the diameter, length and number of elastic rods. One-factor experiments were carried out to substantiate the diameter of the disks and the number of rods. It was found that with the length of the elastic rods of the comb-forming roller 65-75 cm, the diameters of large, medium and small discs, respectively, at least 600mm, 550 mm and 200 mm, the angle of sharpening of the discs within 55-650, the issue of stems within 64 - 69 trimming and diameter bars 3 mm, intensive defeat of chunk and high- quality creation of ridges is ensured.

Prediction of Residual Deformation and Stress of Laser Powder Bed Fusion Manufactured Ti-6Al-4V Lattice Structures Based on Inherent Strain Method

The development of additive manufacturing (AM) technology provides higher feasibility for designing and manufacturing lattice structures. However, the manufacturing process usually generates residual deformation and stress, and even produces cracking, thus affecting the performance of the parts. This work establishes a simulation model of the Ti-6Al-4V lattice structures during laser powder bed fusion (LPBF) based on the inherent strain method. Effects of geometric lattice parameters (inclination angle, rod diameter, rod length) on the residual deformation and stress are analyzed. Based on the simulation results, measures for improving the quality of the lattice structures are proposed. The proposed model and simulation results can provide theoretical references for designing and manufacturing the lattice structures during practical engineering applications of LPBF.

Controlling the transport of the mixture involving active and passive rods in confined channel.

The transport of the binary mixture of self-propelled rods (SPRs) and passive rods in the asymmetric conjugate periodic channel is studied by dissipative particle dynamics (DPD) simulations. It is found that the autonomous pumping of the binary mixture of active and passive rods can be achieved by either the individual or collective behaviour of SPRs. More specifically, the transport of passive rods can be driven through the individual, collective jostlement of the active rods, and crowding out effect. The strength of self-propulsion, rod length, rod concentration, and geometric feature of the channel determines the mechanism of pumping. In addition, the drift of the binary mixture can be in the positive and negative directions of the channel or the currents of SPRs and passive rods in opposite directions and relies on the geometric feature of the channel and concentration of the two species. Overall, our simulation study offers an efficient approach of flow control for both species.

Feasibility study of longitudinal transportation

The research in this paper relates to the technical field of light load transportation, in particular to an electric upstairs car, which includes a frame, the top of the frame is fixedly equipped with a handle, the bottom of the frame is rotationally equipped with a group of wheels, the side wall near the bottom of the frame is fixedly equipped with a carrier plate, the support plate is fixedly arranged between the frames, and the box is fixedly arranged on the side of the support frame away from the carrier plate, A support rod is rotated on the opposite side of the box. The length of the support rod is larger than the diameter of the wheel. An arc surface is set on the support rod. A drive component is set in the box. The drive component is used to drive the support rod to rotate. This kind of electric car that can be transported longitudinally can reduce labor.

Bottom-up on-surface synthesis based on click-functionalized peptide bundles.

On-surface synthesis is a modern technique for the preparation of atomically low-dimensional molecular nanostructures. However, most nanomaterials grow horizontally on the surface, and the step-by-step longitudinally controllable covalent bonding reaction on the surface is rarely reported. Here, we successfully achieved bottom-up on-surface synthesis by using coiled-coil homotetrameric peptide bundles called 'bundlemers' as building blocks. Rigid nano-cylindrical bundlemer with two click-reactive functionalities at each end can be grafted vertically onto the surface or another bundlemer with complementary clickable groups by click reaction at one end, thus enabling the longitudinal bottom-up synthesis of rigid rods with an exact number of bundlemers (up to 6) on the surface. Moreover, we can graft linear poly(ethylene glycol) (PEG) to one terminal of rigid rods to obtain rod-PEG hybrid nanostructures that can be released from the surface under specific conditions. Interestingly, rod-PEG nanostructures consisting of different numbers of bundles can self-assemble in water into different nano-hyperstructures. In general, the bottom-up on-surface synthesis strategy presented here can provide a simple and accurate method to manufacture a variety of nanomaterials.

Analysis of dephasing time of plasmonic hybridization modes using a quasi-normal mode method

Measuring and regulating the localized surface plasmon (LSP) dephasing time (lifetime) of bonding and antibonding modes in nanosystems is the basis for the application of LSP devices. Here, we investigate the modulation of the dephasing time of hybridization modes generated by the coupling between dipole and quadrupole LSP modes in an asymmetric nanorod dimer by combining finite-difference time-domain numerical simulations with the quasi-normal mode (QNM) method. We surprisingly find that the dephasing time of the antibonding mode can be as long as 10.55 fs, which is 30% longer than that of the quadrupole mode supported by an isolated long rod (7.94 fs). Moreover, it is found that the dephasing times of the antibonding and bonding modes can be selectively modulated by changing the gap size or rod length in the dimer. A 6 THz difference between peak frequencies obtained from directly reading the near-field spectra and from the QNM fitting of near-field spectra is observed due to mode interactions existing with a gap size of 60 nm. This work demonstrates that QNM is a superior method in analyzing complex spectra, and it advances our understanding of the dynamical evolution of plasmonic hybrid modes.

Shear induced tuning and memory effects in colloidal gels of rods and spheres.

Shear history plays an important role in determining the linear and nonlinear rheological response of colloidal gels and can be used for tuning their structure and flow properties. Increasing the colloidal particle aspect ratio lowers the critical volume fraction for gelation due to an increase in the particle excluded volume. Using a combination of rheology and confocal microscopy, we investigate the effect of steady and oscillatory preshear history on the structure and rheology of colloidal gels formed by silica spheres and rods of length L and diameter D (L/D = 10) dispersed in 11 M CsCl solution. We use a non-dimensional Mason number, Mn (=Fvisc./Fattr.), to compare the effect of steady and oscillatory preshear on gel viscoelasticity. We show that after preshearing at intermediate Mn, attractive sphere gel exhibits strengthening, whereas attractive rod gel exhibits weakening. Rheo-imaging of gels of attractive rods shows that at intermediate Mn, oscillatory preshear induces large compact rod clusters in the gel microstructure, compared to steady preshear. Our study highlights the impact of particle shape on gel structuring under flow and viscoelasticity after shear cessation.

A new physically realisable internal 1:1 resonance in the coupled pendulum–slosh system

The problem of dynamic coupling between a rectangular container undergoing planar pendular oscillations and its interior potential fluid sloshing is studied. The Neumann boundary-value problem for the fluid motion inside the container is deduced from the Bateman–Luke variational principle. The governing integro-differential equation for the motion of the suspended container, from a single rigid pivoting rod, is the Euler–Lagrange equation for a forced pendulum. The fluid and rigid-body partial differential equations are linearised, and the characteristic equation for the natural and resonant frequencies of the coupled dynamical system are presented. It is found that internal 1:1 resonances exist for an experimentally realistic setup, which has important physical implications. In addition, a new instability is found in the linearised coupled problem whereby instability occurs when the rod length is shorter than a critical length, and an explicit formula is given.

Multiobjective Optimization Design of Truss Antenna

During the design and manufacturing process of the truss antenna, the surface accuracy of the truss antenna is inherently affected by tolerance. An appropriate optimal design of the truss antenna structure is important to improve surface accuracy. In order to receive the optimal design of the truss structure, this paper adopts the multiobjective optimization algorithm based on an approximate model to optimize the tolerance model with random error. Firstly, considering the influence of the processing and assembly errors of the members on the surface accuracy of the structure, the equilibrium state equation of the truss is established by the principle of minimum potential energy. Then, the relationship between the tolerance and the surface accuracy is obtained by the Monte Carlo method. For improving the computing efficiency of the Monte Carlo method, an approximate model of the truss antenna unit is established, where the rod length tolerance is set as the design variable, and the truss surface accuracy and processing cost are set as the objective functions. Finally, tolerance optimization is carried out by using the multiobjective genetic algorithm. The results indicate that the Pareto solution is obtained with an error less than 10%. Moreover, a set of solutions of the tolerance are obtained which can meet different antenna design requirements. And the results show that the influence of the web rod is significantly greater than that of the bottom rod on the surface accuracy of the structure.

Research on size coupling and sensitivity analysis of SAR antenna truss rod

To eliminate the influence of the size coupling of SAR antenna truss rod on assembly accuracy, this paper defines the assembly sequence, part datum, tolerance, assembly operation, and measurement operation of the model by establishing the tolerance analysis model of the assembly dimension chain and measurement target. The assembly simulation process of the deployment mechanism is simulated, the plane deviation of the antenna panel of the deployment mechanism is analyzed, and the contribution and sensitivity data of each component ring size to the closed ring size are obtained. The simulation results show that the in-plane angle error of the antenna panel is mainly affected by the length of the component ring rod. By focusing on controlling the dimensional tolerance of the truss rods with high sensitivity, the assembly accuracy of the antenna deployment system can be guaranteed. Sensitivity is the magnification of assembly deviation by the transmission of deviation source, which reflects the influence of the change of composition tolerance on the change of functional requirements. According to the sensitivity analysis, the key dimensions that affect assembly accuracy can be obtained. The assembly requirements of high-quality and low-cost products can be achieved by strictly controlling the dimensional tolerance of key components and relaxing the tolerance of non-key components.

Hydrazone modification of non-food natural product sclareolide as potential agents for plant disease

Plant diseases and their drug resistance pose a serious threat to agricultural production. One way to solve this problem is to discover new and efficient botanical pesticides. Herein, a series of novel hydrazide-hydrazone-containing sesquiterpenoid derivatives were synthesized by simply modifying the structure of the non-food natural product sclareolide. The biological activity results illustrated that compared to ningnanmycin (39.2 μg/mL), compound Z28 had the highest antiviral activity against tobacco mosaic virus (TMV), and the concentration for 50% of maximal effect (EC50) of its inactivation activity was 38.7 μg/mL, followed by compound Z14 (40.6 μg/mL). Transmission electron microscopy (TEM) demonstrated that TMVs treated with compounds Z14 and Z28 were broken into rods of different lengths, and their external morphology was fragmented or even severely fragmented. Autodocking and molecular dynamics (MD) simulations indicated that compound Z28 had a strong affinity for tobacco mosaic virus coat protein (TMV-CP), with a higher binding energy of −8.25 kcal/mol compared to ningnanmycin (−6.79 kcal/mol). The preliminary mechanism revealed that compound Z28 can achieve an antiviral effect by targeting TMV-CP, rendering TMV unable to self-assemble and replicate, and might be a candidate for a novel plant antiviral agent. Furthermore, the curative and protective activities of compound Z22 (EC50 = 16.1 μg/mL) against rice bacterial blight were 51.3% and 50.8%, respectively. Its control effect was better than that of bismerthiazol (BT) and thiadiazole copper (TC), compound Z22 that can be optimized as an active molecule.

Motion error analysis of a shield machine tool-changing robot based on a screw-vector method

Industrial robots are widely used in various industrial fields, such as handling and welding, due to their good repeat positioning accuracy. The motion error determines the absolute accuracy. For robot design, dimensional parameter errors and drive parameter errors, a mathematical model of a kinematic exponential product with error screws was proposed. The influence of different rod lengths and transmission errors on the accuracy of the end motion was analysed. A composite analysis method based on screw theory and vector method is proposed for the spatial deflection error of robot rotating joints with clearance. By using screw theory, a mathematical error model of the axial movement and spatial deflection of the joint gap was established. A mathematical model of joint space radial movement was established by using the three-dimensional vector method. Through numerical simulation, the position distribution law of the random error of the robot terminal in the workspace and the distribution of the plane projection density were obtained. By solving the attitude matrix, the distribution of each Euler angle error was obtained. A simulation test was carried out to verify the model's correctness. The calculation showed that the method is simple and correct, and the obtained error distribution characteristics are of great significance to improving robotic kinematic calibration accuracy and optimising the spatial position error distribution.

An electroelastic Kirchhoff rod theory incorporating free space electric energy

This work presents a geometrically exact Kirchhoff-like electroelastic rod theory wherein the contribution of free space energy is also factored in. In addition to the usual mechanical variables such as the rod’s centerline and cross-section orientation, three electric potential parameters are also introduced to account for the variation in electric potential within the rod’s cross-section as well as along the rod length. The free space energy is included through an electric flux-like variable acting on the lateral surface of the rod. The governing equations of this rod are derived through balance of forces and moments (arising from both mechanical and electric sources) for mechanical variables, weighted integration of the three-dimensional electric displacement equation in the rod’s cross-section for electric potential parameters and through the asymptotic expansion of a boundary integral equation for the electric flux variable. We also obtain the expressions of internal contact moment and conjugates of electric potential parameters in terms of the rod’s aforementioned mechanical and electric variables. A specific choice of the three-dimensional electroelastic stored energy density is further taken catering to piezoelectric materials and dielectric elastomers and the rod’s constitutive equations are rederived which exhibit interesting interplay between mechanical and electric variables. The presented work can help improve the design of soft electroelastic rod-like actuators and sensors.

Sequence of phase transitions in a model of interacting rods.

In a system of interacting thin rigid rods of equal length 2ℓ on a two-dimensional grid of lattice spacing a, we show that there are multiple phase transitions as the coupling strength κ=ℓ/a and the temperature are varied. There are essentially two classes of transitions. One corresponds to the Ising-type spontaneous symmetry-breaking transition and the second belongs to less-studied phase transitions of geometrical origin. The latter class of transitions appears at fixed values of κ irrespective of the temperature, whereas the critical coupling for the spontaneous symmetry-breaking transition depends on it. By varying the temperature, the phase boundaries may cross each other, leading to a rich phase behavior with infinitely many phases. Our results are based on Monte Carlo simulations on the square lattice and a fixed-point analysis of a functional flow equationon a Bethe lattice.

CZM-based FE numerical study on pull-out performance of adhesive bonded-in-rod (BiR) joints for timber structures

Bonded-in-Rod (BiR) connections for timber structures are becoming rather popular solution, in place of other traditional fastening techniques. Besides, design rules and recommendations in support of safe and robust verification are still poor in existing standards. As such, the actual mechanical performance and load-bearing capacity – which is severely affected by a multitude of operational parameters – should be possibly addressed with the support of experimental investigations. In this paper, a Cohesive Zone Modelling (CZM) based, Finite Element (FE) numerical investigation is proposed for a total of 144 BiR joints characterized by various geometrical and mechanical properties, including grain orientation (α = 0° or 90°), adhesive type (polyurethane or epoxy glue), diameter (d = 10, 14, 20 mm) and anchorage length of rods (L = 60, 100, 200, 400 mm) is presented. Most importantly, the attention is also focused on the analysis of service class effects / moisture content (9, 18 or 27 %) on the actual residual capacity of the examined joints, which is of paramount importance for safe design applications in timber structures. Based on validation of input model properties to past experimental results, the sensitivity of basic mechanical performance indicators for the examined BiR samples is discussed in the paper.

Self-assembly of cellulose nanocrystals of different lengths

HypothesisThe self-assembly (SA) of cellulose nanocrystals (CNC) in suspensions is important both from the fundamental and advanced technology development perspective. CNC of different lengths self-assemble differently in suspensions by balancing attractive and repulsive interactions which depends strongly on morphology, surface chemistry and concentrations.ExperimentsTwo different commercial CNC samples (CNC-M and CNC-C) of different lengths were dispersed in Milli-Q water at different concentrations (0.5–10 wt%). CNC-M is provided as a gel at a solid concentration of 10.3 wt% which was diluted in Milli-Q water. CNC-C is sold as a powder which was dispersed in Milli-Q water with a mixer to achieve the desired concentrations. TEM was used to determine morphology of CNC. Polarised optical microscopy is performed to get microscale visualisation of the chiral nematic self-assembly. High flux synchrotron SAXS is applied to evaluate and compare the nanoscale self-assembly mechanisms of CNC of different lengths.FindingsThe SA of two different types of CNC rods of similar diameter but different lengths is investigated. SAXS analysis shows the short rods in suspension form an isotropic phase (randomly oriented) at lower concentration (0–4 wt%); as concentration is increased, the rods become systematically aligned in a nematic phase. The interrod distance d varies as c−0.33 at the lower concentration, which changes to c−0.5 and even c−1 at the higher concentrations. In contrast, the long rods in suspension remain in the isotropic phase throughout the measured concentration range from 0.5 to 10 wt%. The interrod distance also follows the isotropic power law slope of c−0.33. Suspensions made of the short CNC rods show long range order and large interrod distance compared to those formed by the long rods. POM agrees with the SAXS results. A specific equilibrium between attractive and repulsive forces is required to maintain SA and ordering of the rods. DLVO calculations reveal that the long rods maintain van der Waal attractive force dominating over the electrostatic repulsion, which hinders rods alignment in an ordered manner. However, for the short rods, the weaker attractive interactions are well compensated by the repulsive force which aligns rods in an ordered assembly. This fundamental understanding of the SA of rods in suspensions facilitates the engineering of novel CNC composites of unique optical properties which enables novel applications such as in sensors and bio-diagnostics.