Straight Rods Research Articles

Amorphous metal-organic frameworks-derived In2O3 microstructures with abundant oxygen vacancies for superior chlorine gas sensing performance

Metal-organic frameworks (MOFs) are characterized by their porous structures, which provide an exceptionally large specific surface area and a precisely controlled composition. Amorphous MOFs (aMOFs) integrate the diverse properties of MOFs with those of amorphous materials, such as hierarchical morphology and abundant deficiencies. Therefore, aMOFs serve as promising precursors for metal oxides with porous structures and rich vacancies. NH2-MIL-68 (In) is a novel indium-MOF material with promising features. In this research, the amorphous NH2-MIL-68 (In) (aNH2-MIL-68 (In)) was chosen as the template. Indium oxide rough straight rods (a-In2O3 RSRs) with extensive oxygen vacancies were prepared, where a- indicates that the precursor is amorphous. As a result, the a-In2O3 RSRs sensor demonstrated an outstanding gas sensing response towards 2 ppm chlorine (Cl2) at a low temperature of 160℃. This study is the first to report that the aMOFs can be employed as gas sensing materials with superior Cl2 detection capabilities, offering a promising method for real-time gas monitoring.

Two New Species of Urocleidoides (Monopisthocotyla: Dactylogyridae) Parasitizing the Gills of Cyphocharax modestus (Characiformes: Curimatidae) Supported by Morphological and Molecular Data

The present study describes two new species of monopisthocotylans parasitizing the gills of Cyphocharax modestus (Characiformes: Curimatidae) from two localities of the Upper Paraná River basin, state of São Paulo, Brazil. Urocleidoides saghirus n. sp. and Urocleidoides taquariensis n. sp. differ from other congeners mainly in the morphology of the accessory piece: comprising two subunits (one scythe-shaped subunit, and one adjacent piece with a narrow base broadening towards the upper end, which is axe-shaped) in Urocleidoides saghirus n. sp., and a straight rod with a bifurcated proximal portion, a distal portion ending in a point, and two curved handles arising from the medial portion and uniting close to the distal portion in Urocleidoides taquariensis n. sp. The phylogenetic analyses revealed Urocleidoides to be non-monophyletic, indicating the need for a taxonomic review. This study provides the first molecular sequences for Urocleidoides spp. parasitizing Curimatidae, including the newly described species. These findings revealed distinct clades and suggested possible host specificity, underscoring the importance of additional research to better understand the phylogenetic relationships within the genus.

Dyadobacter helix sp. nov. and Dyadobacter linearis sp. nov., from drinking water.

The purpose of this study is to better characterize and complete the classification of two bacterial strains, CECT 9275T and CECT 9623T, isolated from drinking water systems and affiliated to the genus Dyadobacter by partial 16S rRNA gene sequence comparison. Hence, we report here the phenotypic, genomic and phylogenetic characterization performed on these strains. Both strains grow on R2A agar forming mucous, bright yellow colonies, developing at 26 °C in 48 h. They produce flexirubin and are oxidase and catalase positive, mesophilic and non-halophilic. The cells of strain CECT 9275T are curved rods mainly associated in pairs, forming nearly closed rings or resembling the shape of the number three, to long spirals resembling a corkscrew. Its draft genome has an estimated size of 7.23 Mbp (G+C content 45.4%). Strain CECT 9623T appeared on wet mounts as straight rods, mostly in pairs, sometimes forming long filaments (up to 20 µm). Its draft genome is shorter, with an estimated size of 6.45 Mbp (G+C content is 46.1%). Overall genome relatedness indexes clearly define them as separate organisms, so based on all the data collected, we propose the species Dyadobacter helix sp. nov. with type strain AB1T (=CECT 9275T=LMG 32341T) and Dyadobacter linearis sp. nov. with type strain AB67T (=CECT 9623T=LMG 32342T).

A Self-Oscillator Based on Liquid Crystal Elastomer Fiber Under Constant Voltage.

Self-oscillation is the phenomenon in which a system generates spontaneous, consistent periodic motion in response to a steady external stimulus, making it highly suitable for applications in soft robotics, motors, and mechatronic devices. In this paper, we present a self-oscillator based on liquid crystal elastomer (LCE) fiber under constant voltage. The system primarily consists of an LCE-liquid metal (LCE-LM) composite fiber, a metal mass sphere, and a straight rod featuring both conductive and insulating segments. Building upon an established dynamic LCE model, we derive the governing dynamic equations. Numerical calculations reveal two distinct motion regimes: a static regime and a self-oscillation regime. Furthermore, we provide the temporal behavior curves of electrothermal-induced contraction and tensile force, the phase trajectories variation curves of the equivalent driving force and damping force. These detailed studies elucidate that self-oscillation results from the contraction of the electrothermal-responsive LCE-LM fiber when the circuit is activated, with continuous periodic motion being sustained through the interplay between the metal mass sphere and a self-controlled dynamic circuit. We also investigate the threshold conditions necessary for initiating self-oscillation, as well as the key system parameters that influence its frequency and amplitude. Our self-oscillator demonstrates improved stability by reducing the effects of gravity and other disturbances. Additionally, the curved trajectory of the mass sphere can be achieved by replacing the straight rod with a curved one, resulting in a more flexible and easily controllable structure. Given these characteristics, a self-oscillator system based on LCE-LM fiber may be ideal for creating monitoring and warning devices, dynamic circuit systems, and for integrating actuators and controllers.

Field pullout test and anchorage length calculation for external anchorage of GFRP anti-floating anchors

Field pullout destructive tests of GFRP anti-floating anchors with different anchorage lengths and different anchorage forms are carried out on inverted foundation slabs. Explore the damage patterns and anchorage mechanisms of bent anchors, straight anchors and GFRP anchors with different bending configurations in relation to the concrete foundation slab. Calculate the reasonable anchorage length of anti-floating anchors. The test results show that the straight line anchor rod and bent anchor rod are mainly damaged by sliding. The displacement of anchor rod body decreases with the increase of anchorage length, bending radius and bending length. The bending treatment of anchor rods reduces the pullout bearing capacity of GFRP anti-floating anchors, but it can significantly reduce the rod displacement. The longer the length of the bent section of the anchor rod body and the larger the bending radius, the lower the strength utilization of the anchor rod body. Through the calculation of the test results of different anchorage length anti-floating anchor rods, it is found that the current calculation method for the basic anchorage length of anchor rods is too conservative. For the actual anti-floating project, a more reasonable anchorage length calculation method is proposed, and the reasonable anchorage length of anchor rods for this test condition is 370–530 mm.

Dongia sedimenti sp. nov., isolated from river sediment.

A Gram-stain-negative, non-spore-forming and strictly aerobic bacterial strain, designated R-7T, was isolated from river sediment in Wuxi, Jiangsu, PR China. Cells (1.6-3.8 µm long and 0.6-0.8 µm wide) were slightly curved to straight rods and motile by means of a polar flagellum. The strain grew optimally on Reasoner's 2A medium at 30 °C, pH 7.0 and with 1.0% (w/v) NaCl. Strain R-7T exhibited closest 16S rRNA gene sequence similarities to Dongia mobilis CGMCC 1.7660T (95.4%), D. rigui 04SU4-PT (94.6%) and D. soli D78T (93.8%). The phylogenetic trees based on genomic and 16S rRNA gene sequences showed that strain R-7T was clustered in the genus Dongia. The obtained average nucleotide identity and digital DNA-DNA hybridization values between R-7T and the three type strains of the genus Dongia were 73.4, 72.8 and 72.4% and 19.5, 19.0 and 18.7%, respectively. The major respiratory quinone was Q-10. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, three unidentified aminolipids, two unidentified aminophospholipids and nine unidentified polar lipids. The major cellular fatty acids (>5% of the total) were cyclo-C19 : 0 ω8c, C16 : 0 and C16 : 0 2-OH. The DNA G+C content was 65.5 mol%. On the basis of the evidence presented in this study, strain R-7T represents a novel species of the genus Dongia, for which the name Dongia sedimenti sp. nov. is proposed, with strain R-7T (=KCTC 8082T=MCCC 1K08805T) as the type strain.

Nonlinear vibro-acoustic modulation for microcrack detection of steel strands based on S-transform bispectrum

Fatigue crack detection is an important issue to ensure the safety of steel strands. The key to solve this problem is to extract the nonlinear response generated by fatigue cracks. In this paper, the nonlinear VAM method is used to detect the structural cracks. The structure with fatigue cracks is excited using low-frequency pumping and high-frequency probing, and the power spectrum analysis of the modulated signal is carried out. In view of the shortcomings of spectral analysis, a new method combining S-transform and bispectrum is proposed, which is called S-transform bispectrum. S transform contains the phase factor, which can retain the absolute phase characteristics of each frequency, and has good time–frequency multi-scale focusing performance. The bispectrum can suppress Gaussian noise, retain phase information, and quantitatively describe the quadratic phase coupling in the signal. Then the simulation and experiment of damaged straight rod, helical rod, and steel strands are carried out. The results show that the proposed method can effectively detect the nonlinear features by using the sideband peaks in the S-transform bispectrum three-dimensional plot, and the nonlinear features are important to identify the structure with damage. At the same time, in order to prove the ability of S-transform bispectrum, an S-transform bispectrum detector is used to verify it, which is superior to the spectrum in terms of its ability to localize modulation sidebands. The proposed S-transform bispectrum has a good application prospect and provides a new tool for structural damage detection.

Sphaerotilus uruguayifluvii sp. nov., a novel filamentous bacterium isolated from river water.

Strain C29T, a Gram-staining-negative, straight rod occurring singly, in pairs or short chains, was isolated from floating filamentous biomass of the Uruguay River. The strain was catalase and oxidase positive, chemoorganotrophic, strictly aerobic, non-motile, and grew at pH 6.0-9.0, 15-45°C, and 0-0.5% (w/v) NaCl. Polyhydroxybutyrate was accumulated in nutrient-limited conditions. Phylogenetic analysis based on the 16S rRNA gene revealed that strain C29T had the highest sequence similarity with Leptothrix discophora SS-1T (97.82%), Ideonella livida TBM-1T (97.82%), Vitreoscilla filiformis L1401-2T (97.52%), Sphaerotilus sulfidivorans D-501T (97.50%) and Sphaerotilus natans DSM6575T(97.46%). Other type strains with validly published names had similarities below 97.46%. Further phylogenomic analysis showed that strain C29T was affiliated to the family Sphaerotilaceae. Average nucleotide identity (ANI) and in silico DNA-DNA hybridization (dDDH) values with its phylogenetic relatives were lower than 91 and 41%, respectively, revealing that strain C29T represented a new species. The DNA G + C content of strain C29T was 70.9%. The annotation of the genome of the novel strain shows it possessed genes for the degradation of aromatic compounds. It also contained genes that encode sigma factors involved in response regulation of stress resistance, which is an important function for adaptation and survival in natural niches. Based on the results of the phylogenetic and phenotypic analyses, we propose that strain C29T represents a novel species, for which the name Sphaerotilus uruguayifluvii sp. nov. is proposed. The type strain is C29T (= CCM 9043T = DSM 113250T).

Microfiber Rotational Dynamics In Turbulence

We measure the effect of turbulence on spinning and tumbling rates of microfibers in wall-bounded turbulence. The measurements are performed in a turbulent water channel at Reτ 720. Fibres are 1.2 mm long and 10 m in diameter (aspect ratio 120). Their length ranges from 4 to 12 Kolmogorov length scales. They are neutrally buoyant, inertial-less, and rigid in these flow conditions. Six high-speed cameras image the fibres at the channel centre and in a near-wall region. We employ and further refine a technique of tomographic fibre reconstruction and tracking. Their curved shape is used to define a fibre-fixed reference frame and measure its time-resolved orientation. Thus measurements of tumbling and spinning rates are enabled. We provide a discussion about the uncertainty on the rotation rates based on their shape and angular displacement between time-steps. Based on converged statistics, we observed that the mean and mean square spinning are higher than tumbling rates at both channel centre and near-wall region. In addition, our study reveals that slender, curved fibres behave akin to straight rods, yet their curved shape provides a unique advantage: this curvature allows us to measure all rotational components.

Designing highly efficient interlocking interactions in anisotropic active particles

Cluster formation of microscopic swimmers is key to the formation of biofilms and colonies, efficient motion and nutrient uptake, but, in the absence of other interactions, requires high swimmer concentrations to occur. Here we experimentally and numerically show that cluster formation can be dramatically enhanced by an anisotropic swimmer shape. We analyze a class of model microswimmers with a shape that can be continuously tuned from spherical to bent and straight rods. In all cases, clustering can be described by Michaelis-Menten kinetics governed by a single scaling parameter that depends on particle density and shape only. We rationalize these shape-dependent dynamics from the interplay between interlocking probability and cluster stability. The bent rod shape promotes assembly in an interlocking fashion even at vanishingly low particle densities and we identify the most efficient shape to be a semicircle. Our work provides key insights into how shape can be used to rationally design out-of-equilibrium self-organization, key to creating active functional materials and processes that require two-component assembly with high fidelity.

Faecalibacterium taiwanense sp. nov., isolated from human faeces.

Two Gram-stain-negative, straight rods, non-motile, asporogenous, catalase-negative and obligately anaerobic butyrate-producing strains, HLW78T and CYL33, were isolated from faecal samples of two healthy Taiwanese adults. Phylogenetic analyses of 16S rRNA and DNA mismatch repair protein MutL (mutL) gene sequences revealed that these two novel strains belonged to the genus Faecalibacterium. On the basis of 16S rRNA and mutL gene sequence similarities, the type strains Faecalibacterium butyricigenerans AF52-21T(98.3-98.1 % and 79.0-79.5 % similarity), Faecalibacterium duncaniae A2-165T(97.8-97.9 % and 70.9-80.1 %), Faecalibacterium hattorii APC922/41-1T(97.1-97.3 % and 80.3-80.5 %), Faecalibacterium longum CM04-06T(97.8-98.0% and 78.3 %) and Faecalibacterium prausnitzii ATCC 27768T(97.3-97.4 % and 82.7-82.9 %) were the closest neighbours to the novel strains HLW78T and CYL33. Strains HLW78T and CYL33 had 99.4 % both the 16S rRNA and mutL gene sequence similarities, 97.9 % average nucleotide identity (ANI), 96.3 % average amino acid identity (AAI), and 80.5 % digital DNA-DNA hybridization (dDDH) values, indicating that these two strains are members of the same species. Phylogenomic tree analysis indicated that strains HLW78T and CYL33 formed an independent robust cluster together with F. prausnitzii ATCC 27768T. The ANI, AAI and dDDH values between strain HLW78T and its closest neighbours were below the species delineation thresholds of 77.6-85.1 %, 71.4-85.2 % and 28.3-30.9 %, respectively. The two novel strains could be differentiated from the type strains of their closest Faecalibacterium species based on their cellular fatty acid compositions, which contained C18 : 1 ω7c and lacked C15 : 0 and C17 : 1 ω6c, respectively. Phenotypic, chemotaxonomic and genotypic test results demonstrated that the two novel strains HLW78T and CYL33 represented a single, novel species within the genus Faecalibacterium, for which the name Faecalibacterium taiwanense sp. nov. is proposed. The type strain is HLW78T (=BCRC 81397T=NBRC 116372T).

Mechanical Testing of Sliding on Pivot-Locking Clamp (SOP-LC) Fracture Repair System in Four-Point Bending and Torsion.

The first objective of this study was to compare the mechanical performance of a straight and contoured rod for the sliding on pivot-locking clamp (SOP-LC) system. The second objective was to compare single-cycle bending and torsion of the SOP-LC rod-bone constructs to a bone gap model between two clamp configurations. First experiment, 5 mm diameter rods from the 3.5 mm SOP-LC system, 4 straight and 4 bent rods were mechanically compared in four-point bending. The second experiment, 8 constructs with clamps on a single side of the rod and 8 constructs with clamps on alternating sides were compared in four-point bending and torsion. A torque limiting screwdriver at 2.5N was used for all constructs. There were not significant differences between the noncontoured versus contoured rods. Constructs with clamps on a single side had a significantly higher yield load, yield displacement and bending strength, but the constructs with alternating clamps had a significantly higher initial torsional stiffness. There were no other significant differences. Mild clamp slippage and mild screw bending were noted in all the torsion tested constructs graphically with multiple stiffness slopes and visually on the post-tested constructs. Torque applied to initial screw placement may play a role in reducing clamp slippage. Although bending yield load, bending yield displacement, bending strength and torsional stiffness were improved by different clamp placement, clinically this will depend on fracture type. Further studies are needed for clinical significance.

Experimental assessment of the eigenstress state in two-ply yarns and its effect on tensile properties

Propaedeutical to a better understanding of the mechanics of cables, with potential applications in material science and biology, tensile tests were performed on two-ply yarns made of rubber rods, manufactured by transforming the twist on two adjacent straight rods into tortuosity for the resulting double-helix shape. Modeling of the yarn as a pair of Kirchhoff rods in reciprocal contact, fails to provide results in agreement with experiments, especially when the helix slope angle α tends to π/4, representing the geometric limit for material interpenetration. This discrepancy could not be justified by considering the viscosity of the rods, their cross-sectional distortion, or cohesive/frictional contact. Our contribution starts from the experimental observation that the rods are in an eigenstress state already in the reference balanced configuration. This is characterized by a high twist, dictated by the ratio between torsional and bending rod stiffness, which increases as α decreases, growing unboundedly as α→π/4. Experiments confirm that twisting can significantly increase the tensile stiffness of straight rubber rods, in agreement with non-linear elasticity theory. Tensile tests on the yarns can be reproduced excellently only if the twist-induced stiffening is considered.

A new model for spatial rods incorporating surface energy effects

A new non-classical model for spatial rods incorporating surface energy effects is developed using a surface elasticity theory. A variational formulation based on the principle of minimum total potential energy is employed, which leads to the simultaneous determination of the equilibrium equations and complete boundary conditions. The newly developed spatial rod model contains three surface elasticity constants to account for surface energy effects. The new model recovers the classical elasticity-based Kirchhoff rod model as a special case when the surface energy effects are not considered. To illustrate the new spatial rod model, two sample problems are analytically solved by directly applying the general formulas derived. The first one is the buckling of an elastic rod of circular cross-section with fixed-pinned supports, and the other is the equilibrium analysis of a helical rod deformed from a straight rod. An analytical formula is derived for the critical buckling load required to perturb the axially compressed straight rod, and two closed-form expressions are obtained for the force and couple needed in deforming the helical rod. These formulas reduce to those based on classical elasticity when the surface energy effects are suppressed. For the buckling problem, it is found that the critical buckling load predicted by the current new model is always higher than that given by the classical elasticity-based model, and the difference between the two sets of predicted values is significantly large when the radius of the rod is sufficiently small but diminishes as the rod radius increases. For the helical rod problem, the numerical results reveal that the force and couple predicted by the current model are, respectively, significantly larger and smaller than those predicted by the classical model when the rod radius is very small, but the difference is diminishing with the increase of the rod radius.

Focused shear wave beam propagation through a 3D printed human rib cage

Transient elastography (TE) is used in clinical screenings for liver fibrosis. TE generates shear wave motion in the liver by vibration of a piston at the skin. The small, flat piston in current devices radiates shear waves that diverge from the liver, resulting in low SNR and high failure rates, especially in obese patients. Our group recently introduced focused shear wave beams for TE [Cormack et al., IEEE TBME (2024)], in which vibration of a concave piston generates shear waves that converge towards the focal region, thereby increasing SNR for liver stiffness estimation. However, because piston sizes needed for efficient shear wave focusing are larger than the typical intercostal space, the rib cage that lies between the skin and the liver may cause shear wave aberration and influence stiffness measurement. Here, we present measurements of broadband focused shear wave propagation in tissue-mimicking gel in which are embedded 3D printed human ribs. Both straight elliptical rods and anatomically realistic 3D printed ribs are used as aberrators. Measurements are compared to 3D simulations of shear wave beam propagation [Archer et al., JASA (2023)]. Effects of shear wave aberration by the rib cage depend on shear wavelength, piston-to-rib distance, and piston radius and curvature.

Study on Thin Lamination of Carbon Fiber Based on Mechanical Broadening.

Carbon fiber has excellent mechanical properties and plays an important role in modern industry. However, due to the complexity of the carbon fiber widening process, the industrial application of carbon fiber is limited. By designing the carbon fiber widening equipment of automaton, the relationship between the widening width of carbon fiber and the process parameters is studied, and the optimum developing process parameters are obtained, to improve the performance of carbon fiber composites to a certain extent. In this study, the widening process of carbon fiber was studied based on the mechanical broadening method. Firstly, an automatic broadening equipment was designed, and the effects of the initial tension, the number of straight rods, the number of convex rods, and the drawing speed on the widened width during the broadening process were discussed. The widening effect was evaluated by SEM imaging and mechanical testing. At the same time, the factors affecting the broadening width and broadening defects during the broadening process were analyzed, and the optimal broadening process parameters were obtained. The results showed that within a specific range, a higher initial tension, a greater number of convex rods, and an appropriate speed resulted in relatively smaller damage to the broadening of carbon fibers. Through the design of automatic broadening, this experiment explores optimal broadening process parameters, provides a reference for the improvement of the carbon fiber broadening process and further promotes large-scale industrial applications of carbon fiber.

Energy-minimizing configurations for an elastic rod with self-contact energy close to the inextensible–unshearable and hard-contact limits

We study self-contact configurations of elastic rods by adding a repulsive energy to the bend, twist, shear, and stretch energies of a classical elastic rod. We use a discretized approach, with the parameters of the discrete rod calibrated to approach the continuous case as the number N of rod segments goes to infinity, and use a quasi-Newton approach to minimize the discretized energy. We explore convergence of the results as N→∞, and also as we vary shear, stretch, and contact parameters to approach the inextensible–unshearable and hard-contact limits. For a straight and isotropic rod, we present results for three sets of boundary conditions – loop, buckled strut, and hairpin, in each case as an imposed twist angle is increased – and compare energies and configurations for the non-contact and contact problems. Finally, we show how our results change when isotropy is broken in two ways: by the rod being bent in its undeformed state, or by the rod having unequal bending stiffnesses.

Stability of a compressed-tensioned rod of variable cross-section with combined loading

Objective. The purpose of the study is to determine the stability of a straight rod of variable cross-section under combined axial loading. Method. The longitudinal bending of the rod is described by the classical theory using Bernoulli’s hypothesis, and the critical forces are determined from the Euler problem with appropriate assumptions. Result. An algorithm for a numerical method for solving the problem of determining the eigenvalues of the differential equation for longitudinal bending of a rod is proposed. External loads are considered “dead”. The functions of changing the variable cross-sectional area, variable stiffness and distributed load are considered given. The curved axis of the rod after bifurcation is described using a linear ordinary differential equation. Conclusion. The implementation of the numerical method was carried out by the finite difference method using numerical methods and modern computer software.

The mathematics and mechanics of tug of war

In this paper, we propose a mechanical model for a game of tug of war (rope pulling). We focus on a game opposing two players, modelling each player’s body as a structure composed of straight rods that can be actuated in three different ways to generate a pulling force. We first examine the static problem of two opponents being in a deadlock configuration of mechanical equilibrium; here we show that this situation is essentially governed by the ratio of masses of the players, with the heavier player having a strong advantage. We then turn to the dynamic problem and model the response of the system to an abrupt change in activation by one of the players. In this case, the system exhibits a nontrivial response; in particular, we compare a sudden pulling and a sudden “letting up,” and demonstrate the existence of regimes in which the lighter player can momentarily take the advantage.

A concave four-arc honeycomb with enhanced stiffness and desirable negative Poisson’s effect

The conventional star-shaped honeycomb (CSSH) structure is inherently rich in mechanical properties. Based on the CSSH structure, the Poisson's ratio and Young’s modulus can be improved by adding the tip re-entrant angle (ISSH). In this paper, a new concave four-arc honeycomb (CFAH) structure is proposed by designing the straight rod as a curved rod and retaining the tip re-entrant angle from the ISSH structure. The Young's modulus, specific stiffness and Poisson’s ratio of CFAH structures are derived from Castigliano’s second theorem and Moore’s theorem. The theoretical results show good agreement with the numerical and experimental results. The results show that the normalized effective specific stiffness and normalized effective Young’s modulus of the CFAH structure are further improved by about 12.95% and 16.86%, respectively, compared with the ISSH structure, and more significant auxiliary effects are obtained. CFAH structures show good promise in aerospace, construction and other applications due to their enhanced mechanical property. Meanwhile, the present work provides guidance for the study of concave four-arc honeycomb structures.